1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 4949883d185SAl Viro unsigned seq, m_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 506fceef393SAl Viro struct inode *link_inode; 5079883d185SAl Viro unsigned root_seq; 5089883d185SAl Viro int dfd; 5093859a271SKees Cook } __randomize_layout; 5101f55a6ecSAl Viro 5119883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 512894bc8c4SAl Viro { 513756daf26SNeilBrown struct nameidata *old = current->nameidata; 514756daf26SNeilBrown p->stack = p->internal; 515c8a53ee5SAl Viro p->dfd = dfd; 516c8a53ee5SAl Viro p->name = name; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5189883d185SAl Viro p->saved = old; 519756daf26SNeilBrown current->nameidata = p; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 5229883d185SAl Viro static void restore_nameidata(void) 523894bc8c4SAl Viro { 5249883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529e1a63bbcSAl Viro if (now->stack != now->internal) 530756daf26SNeilBrown kfree(now->stack); 531894bc8c4SAl Viro } 532894bc8c4SAl Viro 533894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 534894bc8c4SAl Viro { 535bc40aee0SAl Viro struct saved *p; 536bc40aee0SAl Viro 537bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5386da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 539bc40aee0SAl Viro GFP_ATOMIC); 540bc40aee0SAl Viro if (unlikely(!p)) 541bc40aee0SAl Viro return -ECHILD; 542bc40aee0SAl Viro } else { 5436da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 544894bc8c4SAl Viro GFP_KERNEL); 545894bc8c4SAl Viro if (unlikely(!p)) 546894bc8c4SAl Viro return -ENOMEM; 547bc40aee0SAl Viro } 548894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 549894bc8c4SAl Viro nd->stack = p; 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro } 552894bc8c4SAl Viro 553397d425dSEric W. Biederman /** 554397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 555397d425dSEric W. Biederman * @path: nameidate to verify 556397d425dSEric W. Biederman * 557397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 558397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 559397d425dSEric W. Biederman */ 560397d425dSEric W. Biederman static bool path_connected(const struct path *path) 561397d425dSEric W. Biederman { 562397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 56395dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 564397d425dSEric W. Biederman 56595dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56695dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 567397d425dSEric W. Biederman return true; 568397d425dSEric W. Biederman 569397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 570397d425dSEric W. Biederman } 571397d425dSEric W. Biederman 572894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 573894bc8c4SAl Viro { 574da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 575894bc8c4SAl Viro return 0; 576894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 577894bc8c4SAl Viro return 0; 578894bc8c4SAl Viro return __nd_alloc_stack(nd); 579894bc8c4SAl Viro } 580894bc8c4SAl Viro 5817973387aSAl Viro static void drop_links(struct nameidata *nd) 5827973387aSAl Viro { 5837973387aSAl Viro int i = nd->depth; 5847973387aSAl Viro while (i--) { 5857973387aSAl Viro struct saved *last = nd->stack + i; 586fceef393SAl Viro do_delayed_call(&last->done); 587fceef393SAl Viro clear_delayed_call(&last->done); 5887973387aSAl Viro } 5897973387aSAl Viro } 5907973387aSAl Viro 5917973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5927973387aSAl Viro { 5937973387aSAl Viro drop_links(nd); 5947973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5957973387aSAl Viro int i; 5967973387aSAl Viro path_put(&nd->path); 5977973387aSAl Viro for (i = 0; i < nd->depth; i++) 5987973387aSAl Viro path_put(&nd->stack[i].link); 59984a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 600102b8af2SAl Viro path_put(&nd->root); 60184a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 602102b8af2SAl Viro } 6037973387aSAl Viro } else { 6047973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6057973387aSAl Viro rcu_read_unlock(); 6067973387aSAl Viro } 6077973387aSAl Viro nd->depth = 0; 6087973387aSAl Viro } 6097973387aSAl Viro 6107973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6117973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6127973387aSAl Viro struct path *path, unsigned seq) 6137973387aSAl Viro { 6147973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6157973387aSAl Viro if (unlikely(res)) { 6167973387aSAl Viro if (res > 0) 6177973387aSAl Viro path->mnt = NULL; 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6227973387aSAl Viro path->dentry = NULL; 6237973387aSAl Viro return false; 6247973387aSAl Viro } 6257973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6267973387aSAl Viro } 6277973387aSAl Viro 6287973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6297973387aSAl Viro { 6307973387aSAl Viro int i; 6317973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6327973387aSAl Viro struct saved *last = nd->stack + i; 6337973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6347973387aSAl Viro drop_links(nd); 6357973387aSAl Viro nd->depth = i + 1; 6367973387aSAl Viro return false; 6377973387aSAl Viro } 6387973387aSAl Viro } 6397973387aSAl Viro return true; 6407973387aSAl Viro } 6417973387aSAl Viro 642ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 643ee594bffSAl Viro { 644ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 645ee594bffSAl Viro return true; 64684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 647ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 648ee594bffSAl Viro } 649ee594bffSAl Viro 65019660af7SAl Viro /* 65131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 65819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 65931e6b01fSNick Piggin */ 66031e6b01fSNick Piggin 66131e6b01fSNick Piggin /** 66219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66319660af7SAl Viro * @nd: nameidata pathwalk data 66439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 66531e6b01fSNick Piggin * 6664675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6674675ac39SAl Viro * for ref-walk mode. 6684675ac39SAl Viro * Must be called from rcu-walk context. 6697973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6707973387aSAl Viro * terminate_walk(). 67131e6b01fSNick Piggin */ 6724675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 67331e6b01fSNick Piggin { 67431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 67531e6b01fSNick Piggin 67631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 677e5c832d5SLinus Torvalds 678e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6797973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6804675ac39SAl Viro goto out1; 68184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 68284a2bd39SAl Viro goto out; 683ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6844675ac39SAl Viro goto out; 6854675ac39SAl Viro rcu_read_unlock(); 6864675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6874675ac39SAl Viro return 0; 6884675ac39SAl Viro 68984a2bd39SAl Viro out1: 6904675ac39SAl Viro nd->path.mnt = NULL; 6914675ac39SAl Viro nd->path.dentry = NULL; 6924675ac39SAl Viro out: 6934675ac39SAl Viro rcu_read_unlock(); 6944675ac39SAl Viro return -ECHILD; 6954675ac39SAl Viro } 6964675ac39SAl Viro 6974675ac39SAl Viro /** 6984675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 6994675ac39SAl Viro * @nd: nameidata pathwalk data 7004675ac39SAl Viro * @dentry: child of nd->path.dentry 7014675ac39SAl Viro * @seq: seq number to check dentry against 7024675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7034675ac39SAl Viro * 7044675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7054675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7064675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7074675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7084675ac39SAl Viro * terminate_walk(). 7094675ac39SAl Viro */ 7104675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7114675ac39SAl Viro { 7124675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7134675ac39SAl Viro 7144675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7154675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7164675ac39SAl Viro goto out2; 7177973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7187973387aSAl Viro goto out2; 7194675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7207973387aSAl Viro goto out1; 72148a066e7SAl Viro 72215570086SLinus Torvalds /* 7234675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7244675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7254675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7264675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7274675ac39SAl Viro * know the parent must still be valid if the child sequence number is 72815570086SLinus Torvalds */ 7294675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 730e5c832d5SLinus Torvalds goto out; 73184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 73284a2bd39SAl Viro goto out_dput; 733e5c832d5SLinus Torvalds /* 734e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 735e5c832d5SLinus Torvalds * still valid and get it if required. 736e5c832d5SLinus Torvalds */ 73784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 73884a2bd39SAl Viro goto out_dput; 7398b61e74fSAl Viro rcu_read_unlock(); 74031e6b01fSNick Piggin return 0; 74119660af7SAl Viro 7427973387aSAl Viro out2: 7437973387aSAl Viro nd->path.mnt = NULL; 7447973387aSAl Viro out1: 7457973387aSAl Viro nd->path.dentry = NULL; 746e5c832d5SLinus Torvalds out: 7478b61e74fSAl Viro rcu_read_unlock(); 74884a2bd39SAl Viro return -ECHILD; 74984a2bd39SAl Viro out_dput: 75084a2bd39SAl Viro rcu_read_unlock(); 75184a2bd39SAl Viro dput(dentry); 75231e6b01fSNick Piggin return -ECHILD; 75331e6b01fSNick Piggin } 75431e6b01fSNick Piggin 7554ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 75634286d66SNick Piggin { 757a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7584ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 759a89f8337SAl Viro else 760a89f8337SAl Viro return 1; 76134286d66SNick Piggin } 76234286d66SNick Piggin 7639f1fafeeSAl Viro /** 7649f1fafeeSAl Viro * complete_walk - successful completion of path walk 7659f1fafeeSAl Viro * @nd: pointer nameidata 76639159de2SJeff Layton * 7679f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7689f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7699f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7709f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7719f1fafeeSAl Viro * need to drop nd->path. 77239159de2SJeff Layton */ 7739f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77439159de2SJeff Layton { 77516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77639159de2SJeff Layton int status; 77739159de2SJeff Layton 7789f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7799f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7809f1fafeeSAl Viro nd->root.mnt = NULL; 7814675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 78248a066e7SAl Viro return -ECHILD; 78348a066e7SAl Viro } 7849f1fafeeSAl Viro 78516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78639159de2SJeff Layton return 0; 78739159de2SJeff Layton 788ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 78916c2cd71SAl Viro return 0; 79016c2cd71SAl Viro 791ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79239159de2SJeff Layton if (status > 0) 79339159de2SJeff Layton return 0; 79439159de2SJeff Layton 79516c2cd71SAl Viro if (!status) 79639159de2SJeff Layton status = -ESTALE; 79716c2cd71SAl Viro 79839159de2SJeff Layton return status; 79939159de2SJeff Layton } 80039159de2SJeff Layton 80118d8c860SAl Viro static void set_root(struct nameidata *nd) 8022a737871SAl Viro { 80331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8049e6697e2SAl Viro 8059e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8068f47a016SAl Viro unsigned seq; 807c28cc364SNick Piggin 808c28cc364SNick Piggin do { 809c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81031e6b01fSNick Piggin nd->root = fs->root; 8118f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 812c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8139e6697e2SAl Viro } else { 8149e6697e2SAl Viro get_fs_root(fs, &nd->root); 81584a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8169e6697e2SAl Viro } 81731e6b01fSNick Piggin } 81831e6b01fSNick Piggin 8191d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 820051d3812SIan Kent { 821051d3812SIan Kent dput(path->dentry); 8224ac91378SJan Blunck if (path->mnt != nd->path.mnt) 823051d3812SIan Kent mntput(path->mnt); 824051d3812SIan Kent } 825051d3812SIan Kent 8267b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8277b9337aaSNick Piggin struct nameidata *nd) 828051d3812SIan Kent { 82931e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8304ac91378SJan Blunck dput(nd->path.dentry); 83131e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8324ac91378SJan Blunck mntput(nd->path.mnt); 8339a229683SHuang Shijie } 83431e6b01fSNick Piggin nd->path.mnt = path->mnt; 8354ac91378SJan Blunck nd->path.dentry = path->dentry; 836051d3812SIan Kent } 837051d3812SIan Kent 838248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 839248fb5b9SAl Viro { 840248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 841248fb5b9SAl Viro struct dentry *d; 842248fb5b9SAl Viro nd->path = nd->root; 843248fb5b9SAl Viro d = nd->path.dentry; 844248fb5b9SAl Viro nd->inode = d->d_inode; 845248fb5b9SAl Viro nd->seq = nd->root_seq; 846248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 847248fb5b9SAl Viro return -ECHILD; 848248fb5b9SAl Viro } else { 849248fb5b9SAl Viro path_put(&nd->path); 850248fb5b9SAl Viro nd->path = nd->root; 851248fb5b9SAl Viro path_get(&nd->path); 852248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 853248fb5b9SAl Viro } 854248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 855248fb5b9SAl Viro return 0; 856248fb5b9SAl Viro } 857248fb5b9SAl Viro 858b5fb63c1SChristoph Hellwig /* 8596b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 860b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 861b5fb63c1SChristoph Hellwig */ 8626e77137bSAl Viro void nd_jump_link(struct path *path) 863b5fb63c1SChristoph Hellwig { 8646e77137bSAl Viro struct nameidata *nd = current->nameidata; 865b5fb63c1SChristoph Hellwig path_put(&nd->path); 866b5fb63c1SChristoph Hellwig 867b5fb63c1SChristoph Hellwig nd->path = *path; 868b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 869b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 870b5fb63c1SChristoph Hellwig } 871b5fb63c1SChristoph Hellwig 872b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 873574197e0SAl Viro { 87421c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 875fceef393SAl Viro do_delayed_call(&last->done); 8766548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 877b9ff4429SAl Viro path_put(&last->link); 878574197e0SAl Viro } 879574197e0SAl Viro 880561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 881561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 88230aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 88330aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 884800179c9SKees Cook 885800179c9SKees Cook /** 886800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88755852635SRandy Dunlap * @nd: nameidata pathwalk data 888800179c9SKees Cook * 889800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 890800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 891800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 892800179c9SKees Cook * processes from failing races against path names that may change out 893800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 894800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 895800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 896800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 897800179c9SKees Cook * 898800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 899800179c9SKees Cook */ 900fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 901800179c9SKees Cook { 902800179c9SKees Cook const struct inode *inode; 903800179c9SKees Cook const struct inode *parent; 9042d7f9e2aSSeth Forshee kuid_t puid; 905800179c9SKees Cook 906800179c9SKees Cook if (!sysctl_protected_symlinks) 907800179c9SKees Cook return 0; 908800179c9SKees Cook 909800179c9SKees Cook /* Allowed if owner and follower match. */ 910fceef393SAl Viro inode = nd->link_inode; 91181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 912800179c9SKees Cook return 0; 913800179c9SKees Cook 914800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 915aa65fa35SAl Viro parent = nd->inode; 916800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 917800179c9SKees Cook return 0; 918800179c9SKees Cook 919800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9202d7f9e2aSSeth Forshee puid = parent->i_uid; 9212d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 922800179c9SKees Cook return 0; 923800179c9SKees Cook 92431956502SAl Viro if (nd->flags & LOOKUP_RCU) 92531956502SAl Viro return -ECHILD; 92631956502SAl Viro 927ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 928245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 929800179c9SKees Cook return -EACCES; 930800179c9SKees Cook } 931800179c9SKees Cook 932800179c9SKees Cook /** 933800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 934800179c9SKees Cook * @inode: the source inode to hardlink from 935800179c9SKees Cook * 936800179c9SKees Cook * Return false if at least one of the following conditions: 937800179c9SKees Cook * - inode is not a regular file 938800179c9SKees Cook * - inode is setuid 939800179c9SKees Cook * - inode is setgid and group-exec 940800179c9SKees Cook * - access failure for read and write 941800179c9SKees Cook * 942800179c9SKees Cook * Otherwise returns true. 943800179c9SKees Cook */ 944800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 945800179c9SKees Cook { 946800179c9SKees Cook umode_t mode = inode->i_mode; 947800179c9SKees Cook 948800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 949800179c9SKees Cook if (!S_ISREG(mode)) 950800179c9SKees Cook return false; 951800179c9SKees Cook 952800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 953800179c9SKees Cook if (mode & S_ISUID) 954800179c9SKees Cook return false; 955800179c9SKees Cook 956800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 957800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 958800179c9SKees Cook return false; 959800179c9SKees Cook 960800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 961800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 962800179c9SKees Cook return false; 963800179c9SKees Cook 964800179c9SKees Cook return true; 965800179c9SKees Cook } 966800179c9SKees Cook 967800179c9SKees Cook /** 968800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 969800179c9SKees Cook * @link: the source to hardlink from 970800179c9SKees Cook * 971800179c9SKees Cook * Block hardlink when all of: 972800179c9SKees Cook * - sysctl_protected_hardlinks enabled 973800179c9SKees Cook * - fsuid does not match inode 974800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 975f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 976800179c9SKees Cook * 977800179c9SKees Cook * Returns 0 if successful, -ve on error. 978800179c9SKees Cook */ 979800179c9SKees Cook static int may_linkat(struct path *link) 980800179c9SKees Cook { 981593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 982593d1ce8SEric W. Biederman 983593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 984593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 985593d1ce8SEric W. Biederman return -EOVERFLOW; 986800179c9SKees Cook 987800179c9SKees Cook if (!sysctl_protected_hardlinks) 988800179c9SKees Cook return 0; 989800179c9SKees Cook 990800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 991800179c9SKees Cook * otherwise, it must be a safe source. 992800179c9SKees Cook */ 993cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 994800179c9SKees Cook return 0; 995800179c9SKees Cook 996245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 997800179c9SKees Cook return -EPERM; 998800179c9SKees Cook } 999800179c9SKees Cook 100030aba665SSalvatore Mesoraca /** 100130aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 100230aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 100330aba665SSalvatore Mesoraca * exist. 100430aba665SSalvatore Mesoraca * @dir: the sticky parent directory 100530aba665SSalvatore Mesoraca * @inode: the inode of the file to open 100630aba665SSalvatore Mesoraca * 100730aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 100830aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 100930aba665SSalvatore Mesoraca * - the file already exists 101030aba665SSalvatore Mesoraca * - we are in a sticky directory 101130aba665SSalvatore Mesoraca * - we don't own the file 101230aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 101330aba665SSalvatore Mesoraca * - the directory is world writable 101430aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 101530aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 101630aba665SSalvatore Mesoraca * be enough. 101730aba665SSalvatore Mesoraca * 101830aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 101930aba665SSalvatore Mesoraca */ 102030aba665SSalvatore Mesoraca static int may_create_in_sticky(struct dentry * const dir, 102130aba665SSalvatore Mesoraca struct inode * const inode) 102230aba665SSalvatore Mesoraca { 102330aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 102430aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 102530aba665SSalvatore Mesoraca likely(!(dir->d_inode->i_mode & S_ISVTX)) || 102630aba665SSalvatore Mesoraca uid_eq(inode->i_uid, dir->d_inode->i_uid) || 102730aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 102830aba665SSalvatore Mesoraca return 0; 102930aba665SSalvatore Mesoraca 103030aba665SSalvatore Mesoraca if (likely(dir->d_inode->i_mode & 0002) || 103130aba665SSalvatore Mesoraca (dir->d_inode->i_mode & 0020 && 103230aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 103330aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1034245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1035245d7369SKees Cook "sticky_create_fifo" : 1036245d7369SKees Cook "sticky_create_regular"; 1037245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 103830aba665SSalvatore Mesoraca return -EACCES; 103930aba665SSalvatore Mesoraca } 104030aba665SSalvatore Mesoraca return 0; 104130aba665SSalvatore Mesoraca } 104230aba665SSalvatore Mesoraca 10433b2e7f75SAl Viro static __always_inline 10443b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10451da177e4SLinus Torvalds { 1046ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10471cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1048fceef393SAl Viro struct inode *inode = nd->link_inode; 10496d7b5aaeSAl Viro int error; 10500a959df5SAl Viro const char *res; 10511da177e4SLinus Torvalds 10528fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10538fa9dd24SNeilBrown touch_atime(&last->link); 10548fa9dd24SNeilBrown cond_resched(); 1055c6718543SMiklos Szeredi } else if (atime_needs_update(&last->link, inode)) { 10564675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10578fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10588fa9dd24SNeilBrown touch_atime(&last->link); 10598fa9dd24SNeilBrown } 10608fa9dd24SNeilBrown 1061bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1062bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1063bda0be7aSNeilBrown if (unlikely(error)) 10646920a440SAl Viro return ERR_PTR(error); 106536f3b4f6SAl Viro 106686acdca1SAl Viro nd->last_type = LAST_BIND; 10674c4f7c19SEric Biggers res = READ_ONCE(inode->i_link); 1068d4dee48bSAl Viro if (!res) { 1069fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1070fceef393SAl Viro struct delayed_call *); 1071fceef393SAl Viro get = inode->i_op->get_link; 10728c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1073fceef393SAl Viro res = get(NULL, inode, &last->done); 10746b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10754675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10768c1b4566SAl Viro return ERR_PTR(-ECHILD); 1077fceef393SAl Viro res = get(dentry, inode, &last->done); 10788c1b4566SAl Viro } 10796b255391SAl Viro } else { 1080fceef393SAl Viro res = get(dentry, inode, &last->done); 10816b255391SAl Viro } 1082fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1083fab51e8aSAl Viro return res; 10840a959df5SAl Viro } 1085fab51e8aSAl Viro if (*res == '/') { 1086fab51e8aSAl Viro if (!nd->root.mnt) 1087fab51e8aSAl Viro set_root(nd); 1088248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1089fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1090fab51e8aSAl Viro while (unlikely(*++res == '/')) 1091fab51e8aSAl Viro ; 1092fab51e8aSAl Viro } 1093fab51e8aSAl Viro if (!*res) 1094fab51e8aSAl Viro res = NULL; 10950a959df5SAl Viro return res; 10960a959df5SAl Viro } 10976d7b5aaeSAl Viro 1098f015f126SDavid Howells /* 1099f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1100f015f126SDavid Howells * 1101f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1102f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1103f015f126SDavid Howells * Up is towards /. 1104f015f126SDavid Howells * 1105f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1106f015f126SDavid Howells * root. 1107f015f126SDavid Howells */ 1108bab77ebfSAl Viro int follow_up(struct path *path) 11091da177e4SLinus Torvalds { 11100714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11110714a533SAl Viro struct mount *parent; 11121da177e4SLinus Torvalds struct dentry *mountpoint; 111399b7db7bSNick Piggin 111448a066e7SAl Viro read_seqlock_excl(&mount_lock); 11150714a533SAl Viro parent = mnt->mnt_parent; 11163c0a6163SAl Viro if (parent == mnt) { 111748a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11181da177e4SLinus Torvalds return 0; 11191da177e4SLinus Torvalds } 11200714a533SAl Viro mntget(&parent->mnt); 1121a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 112248a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1123bab77ebfSAl Viro dput(path->dentry); 1124bab77ebfSAl Viro path->dentry = mountpoint; 1125bab77ebfSAl Viro mntput(path->mnt); 11260714a533SAl Viro path->mnt = &parent->mnt; 11271da177e4SLinus Torvalds return 1; 11281da177e4SLinus Torvalds } 11294d359507SAl Viro EXPORT_SYMBOL(follow_up); 11301da177e4SLinus Torvalds 1131b5c84bf6SNick Piggin /* 11329875cf80SDavid Howells * Perform an automount 11339875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11349875cf80SDavid Howells * were called with. 11351da177e4SLinus Torvalds */ 1136756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11379875cf80SDavid Howells bool *need_mntput) 113831e6b01fSNick Piggin { 11399875cf80SDavid Howells struct vfsmount *mnt; 1140ea5b778aSDavid Howells int err; 11419875cf80SDavid Howells 11429875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11439875cf80SDavid Howells return -EREMOTE; 11449875cf80SDavid Howells 11450ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11460ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11470ec26fd0SMiklos Szeredi * the name. 11480ec26fd0SMiklos Szeredi * 11490ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11505a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11510ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11520ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11530ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11540ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11555a30d8a2SDavid Howells */ 1156756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11575d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11585d38f049SIan Kent path->dentry->d_inode) 11599875cf80SDavid Howells return -EISDIR; 11600ec26fd0SMiklos Szeredi 1161756daf26SNeilBrown nd->total_link_count++; 1162756daf26SNeilBrown if (nd->total_link_count >= 40) 11639875cf80SDavid Howells return -ELOOP; 11649875cf80SDavid Howells 11659875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11669875cf80SDavid Howells if (IS_ERR(mnt)) { 11679875cf80SDavid Howells /* 11689875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11699875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11709875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11719875cf80SDavid Howells * 11729875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11739875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11749875cf80SDavid Howells * the path is inaccessible and we should say so. 11759875cf80SDavid Howells */ 1176756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11779875cf80SDavid Howells return -EREMOTE; 11789875cf80SDavid Howells return PTR_ERR(mnt); 117931e6b01fSNick Piggin } 1180ea5b778aSDavid Howells 11819875cf80SDavid Howells if (!mnt) /* mount collision */ 11829875cf80SDavid Howells return 0; 11839875cf80SDavid Howells 11848aef1884SAl Viro if (!*need_mntput) { 11858aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11868aef1884SAl Viro mntget(path->mnt); 11878aef1884SAl Viro *need_mntput = true; 11888aef1884SAl Viro } 118919a167afSAl Viro err = finish_automount(mnt, path); 1190ea5b778aSDavid Howells 1191ea5b778aSDavid Howells switch (err) { 1192ea5b778aSDavid Howells case -EBUSY: 1193ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 119419a167afSAl Viro return 0; 1195ea5b778aSDavid Howells case 0: 11968aef1884SAl Viro path_put(path); 11979875cf80SDavid Howells path->mnt = mnt; 11989875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11999875cf80SDavid Howells return 0; 120019a167afSAl Viro default: 120119a167afSAl Viro return err; 12029875cf80SDavid Howells } 120319a167afSAl Viro 1204ea5b778aSDavid Howells } 12059875cf80SDavid Howells 12069875cf80SDavid Howells /* 12079875cf80SDavid Howells * Handle a dentry that is managed in some way. 1208cc53ce53SDavid Howells * - Flagged for transit management (autofs) 12099875cf80SDavid Howells * - Flagged as mountpoint 12109875cf80SDavid Howells * - Flagged as automount point 12119875cf80SDavid Howells * 12129875cf80SDavid Howells * This may only be called in refwalk mode. 12139875cf80SDavid Howells * 12149875cf80SDavid Howells * Serialization is taken care of in namespace.c 12159875cf80SDavid Howells */ 1216756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12179875cf80SDavid Howells { 12188aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 12199875cf80SDavid Howells unsigned managed; 12209875cf80SDavid Howells bool need_mntput = false; 12218aef1884SAl Viro int ret = 0; 12229875cf80SDavid Howells 12239875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12249875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 12259875cf80SDavid Howells * the components of that value change under us */ 12266aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 12279875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 12289875cf80SDavid Howells unlikely(managed != 0)) { 1229cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1230cc53ce53SDavid Howells * being held. */ 1231cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1232cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1233cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1234fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1235cc53ce53SDavid Howells if (ret < 0) 12368aef1884SAl Viro break; 1237cc53ce53SDavid Howells } 1238cc53ce53SDavid Howells 12399875cf80SDavid Howells /* Transit to a mounted filesystem. */ 12409875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 12419875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12429875cf80SDavid Howells if (mounted) { 12439875cf80SDavid Howells dput(path->dentry); 12449875cf80SDavid Howells if (need_mntput) 1245463ffb2eSAl Viro mntput(path->mnt); 1246463ffb2eSAl Viro path->mnt = mounted; 1247463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12489875cf80SDavid Howells need_mntput = true; 12499875cf80SDavid Howells continue; 1250463ffb2eSAl Viro } 1251463ffb2eSAl Viro 12529875cf80SDavid Howells /* Something is mounted on this dentry in another 12539875cf80SDavid Howells * namespace and/or whatever was mounted there in this 125448a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 125548a066e7SAl Viro * get it */ 12561da177e4SLinus Torvalds } 12579875cf80SDavid Howells 12589875cf80SDavid Howells /* Handle an automount point */ 12599875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1260756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12619875cf80SDavid Howells if (ret < 0) 12628aef1884SAl Viro break; 12639875cf80SDavid Howells continue; 12649875cf80SDavid Howells } 12659875cf80SDavid Howells 12669875cf80SDavid Howells /* We didn't change the current path point */ 12679875cf80SDavid Howells break; 12689875cf80SDavid Howells } 12698aef1884SAl Viro 12708aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12718aef1884SAl Viro mntput(path->mnt); 1272e9742b53SAl Viro if (ret == -EISDIR || !ret) 1273e9742b53SAl Viro ret = 1; 12748402752eSAl Viro if (need_mntput) 12758402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12768402752eSAl Viro if (unlikely(ret < 0)) 12778402752eSAl Viro path_put_conditional(path, nd); 12788402752eSAl Viro return ret; 12791da177e4SLinus Torvalds } 12801da177e4SLinus Torvalds 1281cc53ce53SDavid Howells int follow_down_one(struct path *path) 12821da177e4SLinus Torvalds { 12831da177e4SLinus Torvalds struct vfsmount *mounted; 12841da177e4SLinus Torvalds 12851c755af4SAl Viro mounted = lookup_mnt(path); 12861da177e4SLinus Torvalds if (mounted) { 12879393bd07SAl Viro dput(path->dentry); 12889393bd07SAl Viro mntput(path->mnt); 12899393bd07SAl Viro path->mnt = mounted; 12909393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12911da177e4SLinus Torvalds return 1; 12921da177e4SLinus Torvalds } 12931da177e4SLinus Torvalds return 0; 12941da177e4SLinus Torvalds } 12954d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12961da177e4SLinus Torvalds 1297fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 129862a7375eSIan Kent { 1299fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1300fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 130162a7375eSIan Kent } 130262a7375eSIan Kent 13039875cf80SDavid Howells /* 1304287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1305287548e4SAl Viro * we meet a managed dentry that would need blocking. 13069875cf80SDavid Howells */ 13079875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1308254cf582SAl Viro struct inode **inode, unsigned *seqp) 13099875cf80SDavid Howells { 131062a7375eSIan Kent for (;;) { 1311c7105365SAl Viro struct mount *mounted; 131262a7375eSIan Kent /* 131362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 131462a7375eSIan Kent * that wants to block transit. 131562a7375eSIan Kent */ 1316fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1317b8faf035SNeilBrown case -ECHILD: 1318b8faf035SNeilBrown default: 1319ab90911fSDavid Howells return false; 1320b8faf035SNeilBrown case -EISDIR: 1321b8faf035SNeilBrown return true; 1322b8faf035SNeilBrown case 0: 1323b8faf035SNeilBrown break; 1324b8faf035SNeilBrown } 132562a7375eSIan Kent 132662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1327b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 132862a7375eSIan Kent 1329474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13309875cf80SDavid Howells if (!mounted) 13319875cf80SDavid Howells break; 1332c7105365SAl Viro path->mnt = &mounted->mnt; 1333c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1334a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1335254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 133659430262SLinus Torvalds /* 133759430262SLinus Torvalds * Update the inode too. We don't need to re-check the 133859430262SLinus Torvalds * dentry sequence number here after this d_inode read, 133959430262SLinus Torvalds * because a mount-point is always pinned. 134059430262SLinus Torvalds */ 134159430262SLinus Torvalds *inode = path->dentry->d_inode; 13429875cf80SDavid Howells } 1343f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1344b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1345287548e4SAl Viro } 1346287548e4SAl Viro 134731e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 134831e6b01fSNick Piggin { 13494023bfc9SAl Viro struct inode *inode = nd->inode; 135031e6b01fSNick Piggin 135131e6b01fSNick Piggin while (1) { 1352aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 135331e6b01fSNick Piggin break; 135431e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 135531e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 135631e6b01fSNick Piggin struct dentry *parent = old->d_parent; 135731e6b01fSNick Piggin unsigned seq; 135831e6b01fSNick Piggin 13594023bfc9SAl Viro inode = parent->d_inode; 136031e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1361aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1362aed434adSAl Viro return -ECHILD; 136331e6b01fSNick Piggin nd->path.dentry = parent; 136431e6b01fSNick Piggin nd->seq = seq; 1365397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1366397d425dSEric W. Biederman return -ENOENT; 136731e6b01fSNick Piggin break; 1368aed434adSAl Viro } else { 1369aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1370aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1371aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1372aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1373aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1374aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1375aed434adSAl Viro return -ECHILD; 1376aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 137731e6b01fSNick Piggin break; 1378aed434adSAl Viro /* we know that mountpoint was pinned */ 1379aed434adSAl Viro nd->path.dentry = mountpoint; 1380aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1381aed434adSAl Viro inode = inode2; 1382aed434adSAl Viro nd->seq = seq; 138331e6b01fSNick Piggin } 1384aed434adSAl Viro } 1385aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1386b37199e6SAl Viro struct mount *mounted; 1387b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1388aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1389aed434adSAl Viro return -ECHILD; 1390b37199e6SAl Viro if (!mounted) 1391b37199e6SAl Viro break; 1392b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1393b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13944023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1395b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1396b37199e6SAl Viro } 13974023bfc9SAl Viro nd->inode = inode; 139831e6b01fSNick Piggin return 0; 139931e6b01fSNick Piggin } 140031e6b01fSNick Piggin 14019875cf80SDavid Howells /* 1402cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1403cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1404cc53ce53SDavid Howells * caller is permitted to proceed or not. 1405cc53ce53SDavid Howells */ 14067cc90cc3SAl Viro int follow_down(struct path *path) 1407cc53ce53SDavid Howells { 1408cc53ce53SDavid Howells unsigned managed; 1409cc53ce53SDavid Howells int ret; 1410cc53ce53SDavid Howells 14116aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1412cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1413cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1414cc53ce53SDavid Howells * being held. 1415cc53ce53SDavid Howells * 1416cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1417cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1418cc53ce53SDavid Howells * other than its daemon the right to mount on its 1419cc53ce53SDavid Howells * superstructure. 1420cc53ce53SDavid Howells * 1421cc53ce53SDavid Howells * The filesystem may sleep at this point. 1422cc53ce53SDavid Howells */ 1423cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1424cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1425cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1426fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1427cc53ce53SDavid Howells if (ret < 0) 1428cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1429cc53ce53SDavid Howells } 1430cc53ce53SDavid Howells 1431cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1432cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1433cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1434cc53ce53SDavid Howells if (!mounted) 1435cc53ce53SDavid Howells break; 1436cc53ce53SDavid Howells dput(path->dentry); 1437cc53ce53SDavid Howells mntput(path->mnt); 1438cc53ce53SDavid Howells path->mnt = mounted; 1439cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1440cc53ce53SDavid Howells continue; 1441cc53ce53SDavid Howells } 1442cc53ce53SDavid Howells 1443cc53ce53SDavid Howells /* Don't handle automount points here */ 1444cc53ce53SDavid Howells break; 1445cc53ce53SDavid Howells } 1446cc53ce53SDavid Howells return 0; 1447cc53ce53SDavid Howells } 14484d359507SAl Viro EXPORT_SYMBOL(follow_down); 1449cc53ce53SDavid Howells 1450cc53ce53SDavid Howells /* 14519875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14529875cf80SDavid Howells */ 14539875cf80SDavid Howells static void follow_mount(struct path *path) 14549875cf80SDavid Howells { 14559875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14569875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14579875cf80SDavid Howells if (!mounted) 14589875cf80SDavid Howells break; 14599875cf80SDavid Howells dput(path->dentry); 14609875cf80SDavid Howells mntput(path->mnt); 14619875cf80SDavid Howells path->mnt = mounted; 14629875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14639875cf80SDavid Howells } 14649875cf80SDavid Howells } 14659875cf80SDavid Howells 1466eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1467eedf265aSEric W. Biederman { 1468eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1469eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1470eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1471eedf265aSEric W. Biederman dput(old); 1472eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1473eedf265aSEric W. Biederman return -ENOENT; 1474eedf265aSEric W. Biederman return 0; 1475eedf265aSEric W. Biederman } 1476eedf265aSEric W. Biederman 1477397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14781da177e4SLinus Torvalds { 14791da177e4SLinus Torvalds while(1) { 1480030c7e0bSDanilo Krummrich if (path_equal(&nd->path, &nd->root)) 14811da177e4SLinus Torvalds break; 14824ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1483eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1484eedf265aSEric W. Biederman if (ret) 1485eedf265aSEric W. Biederman return ret; 14861da177e4SLinus Torvalds break; 14871da177e4SLinus Torvalds } 14883088dd70SAl Viro if (!follow_up(&nd->path)) 14891da177e4SLinus Torvalds break; 14901da177e4SLinus Torvalds } 149179ed0226SAl Viro follow_mount(&nd->path); 149231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1493397d425dSEric W. Biederman return 0; 14941da177e4SLinus Torvalds } 14951da177e4SLinus Torvalds 14961da177e4SLinus Torvalds /* 1497f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1498f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1499baa03890SNick Piggin */ 1500e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1501e3c13928SAl Viro struct dentry *dir, 15026c51e513SAl Viro unsigned int flags) 1503baa03890SNick Piggin { 1504a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1505bad61189SMiklos Szeredi if (dentry) { 1506a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1507bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 150874ff0ffcSAl Viro if (!error) 15095542aa2fSEric W. Biederman d_invalidate(dentry); 1510bad61189SMiklos Szeredi dput(dentry); 151174ff0ffcSAl Viro return ERR_PTR(error); 1512bad61189SMiklos Szeredi } 1513bad61189SMiklos Szeredi } 1514baa03890SNick Piggin return dentry; 1515baa03890SNick Piggin } 1516baa03890SNick Piggin 1517baa03890SNick Piggin /* 1518a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1519a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1520a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1521a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1522a03ece5fSAl Viro * at all. 152344396f4bSJosef Bacik */ 1524a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1525a03ece5fSAl Viro struct dentry *base, unsigned int flags) 152644396f4bSJosef Bacik { 1527a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 152844396f4bSJosef Bacik struct dentry *old; 1529a03ece5fSAl Viro struct inode *dir = base->d_inode; 1530a03ece5fSAl Viro 1531a03ece5fSAl Viro if (dentry) 1532a03ece5fSAl Viro return dentry; 153344396f4bSJosef Bacik 153444396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1535a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 153644396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1537a03ece5fSAl Viro 1538a03ece5fSAl Viro dentry = d_alloc(base, name); 1539a03ece5fSAl Viro if (unlikely(!dentry)) 1540a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 154144396f4bSJosef Bacik 154272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 154344396f4bSJosef Bacik if (unlikely(old)) { 154444396f4bSJosef Bacik dput(dentry); 154544396f4bSJosef Bacik dentry = old; 154644396f4bSJosef Bacik } 154744396f4bSJosef Bacik return dentry; 154844396f4bSJosef Bacik } 154944396f4bSJosef Bacik 1550e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1551254cf582SAl Viro struct path *path, struct inode **inode, 1552254cf582SAl Viro unsigned *seqp) 15531da177e4SLinus Torvalds { 15544ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 155531e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15565a18fff2SAl Viro int status = 1; 15579875cf80SDavid Howells int err; 15589875cf80SDavid Howells 15593cac260aSAl Viro /* 1560b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15615d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15625d0f49c1SAl Viro * going to fall back to non-racy lookup. 1563b04f784eSNick Piggin */ 156431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 156531e6b01fSNick Piggin unsigned seq; 1566766c4cbfSAl Viro bool negative; 1567da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15685d0f49c1SAl Viro if (unlikely(!dentry)) { 15694675ac39SAl Viro if (unlazy_walk(nd)) 15705d0f49c1SAl Viro return -ECHILD; 1571e9742b53SAl Viro return 0; 15725d0f49c1SAl Viro } 15735a18fff2SAl Viro 157412f8ad4bSLinus Torvalds /* 157512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 157612f8ad4bSLinus Torvalds * the dentry name information from lookup. 157712f8ad4bSLinus Torvalds */ 157863afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1579766c4cbfSAl Viro negative = d_is_negative(dentry); 15805d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 158112f8ad4bSLinus Torvalds return -ECHILD; 158212f8ad4bSLinus Torvalds 158312f8ad4bSLinus Torvalds /* 158412f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 158512f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 158612f8ad4bSLinus Torvalds * 158712f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 158812f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 158912f8ad4bSLinus Torvalds */ 15905d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 159131e6b01fSNick Piggin return -ECHILD; 15925a18fff2SAl Viro 1593254cf582SAl Viro *seqp = seq; 15944ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1595209a7fb2SAl Viro if (likely(status > 0)) { 1596daf3761cSTrond Myklebust /* 1597daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1598daf3761cSTrond Myklebust * case that drops it. 1599daf3761cSTrond Myklebust */ 16005d0f49c1SAl Viro if (unlikely(negative)) 1601daf3761cSTrond Myklebust return -ENOENT; 160231e6b01fSNick Piggin path->mnt = mnt; 160331e6b01fSNick Piggin path->dentry = dentry; 1604254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1605e9742b53SAl Viro return 1; 16065d0f49c1SAl Viro } 16074675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1608254cf582SAl Viro return -ECHILD; 1609209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1610209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1611209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16125a18fff2SAl Viro } else { 1613e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 161481e6f520SAl Viro if (unlikely(!dentry)) 1615e9742b53SAl Viro return 0; 16164ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16175d0f49c1SAl Viro } 16185a18fff2SAl Viro if (unlikely(status <= 0)) { 1619e9742b53SAl Viro if (!status) 16205d0f49c1SAl Viro d_invalidate(dentry); 16215a18fff2SAl Viro dput(dentry); 16225a18fff2SAl Viro return status; 16235a18fff2SAl Viro } 1624766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1625766c4cbfSAl Viro dput(dentry); 1626766c4cbfSAl Viro return -ENOENT; 1627766c4cbfSAl Viro } 16285d0f49c1SAl Viro 16291da177e4SLinus Torvalds path->mnt = mnt; 16301da177e4SLinus Torvalds path->dentry = dentry; 1631756daf26SNeilBrown err = follow_managed(path, nd); 1632e9742b53SAl Viro if (likely(err > 0)) 163363afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16348402752eSAl Viro return err; 1635697f514dSMiklos Szeredi } 1636697f514dSMiklos Szeredi 1637697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 163888d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1639e3c13928SAl Viro struct dentry *dir, 1640e3c13928SAl Viro unsigned int flags) 1641697f514dSMiklos Szeredi { 164288d8331aSAl Viro struct dentry *dentry, *old; 16431936386eSAl Viro struct inode *inode = dir->d_inode; 1644d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16451936386eSAl Viro 16461936386eSAl Viro /* Don't go there if it's already dead */ 164794bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 164888d8331aSAl Viro return ERR_PTR(-ENOENT); 164994bdd655SAl Viro again: 1650d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 165194bdd655SAl Viro if (IS_ERR(dentry)) 165288d8331aSAl Viro return dentry; 165394bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1654a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1655949a852eSAl Viro int error = d_revalidate(dentry, flags); 1656949a852eSAl Viro if (unlikely(error <= 0)) { 165794bdd655SAl Viro if (!error) { 1658949a852eSAl Viro d_invalidate(dentry); 1659949a852eSAl Viro dput(dentry); 166094bdd655SAl Viro goto again; 166194bdd655SAl Viro } 166294bdd655SAl Viro dput(dentry); 1663949a852eSAl Viro dentry = ERR_PTR(error); 1664949a852eSAl Viro } 1665949a852eSAl Viro } 166694bdd655SAl Viro } else { 16671936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 166885c7f810SAl Viro d_lookup_done(dentry); 16691936386eSAl Viro if (unlikely(old)) { 16701936386eSAl Viro dput(dentry); 16711936386eSAl Viro dentry = old; 1672949a852eSAl Viro } 1673949a852eSAl Viro } 1674e3c13928SAl Viro return dentry; 16751da177e4SLinus Torvalds } 16761da177e4SLinus Torvalds 167788d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 167888d8331aSAl Viro struct dentry *dir, 167988d8331aSAl Viro unsigned int flags) 168088d8331aSAl Viro { 168188d8331aSAl Viro struct inode *inode = dir->d_inode; 168288d8331aSAl Viro struct dentry *res; 168388d8331aSAl Viro inode_lock_shared(inode); 168488d8331aSAl Viro res = __lookup_slow(name, dir, flags); 168588d8331aSAl Viro inode_unlock_shared(inode); 168688d8331aSAl Viro return res; 168788d8331aSAl Viro } 168888d8331aSAl Viro 168952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 169052094c8aSAl Viro { 169152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16924ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 169352094c8aSAl Viro if (err != -ECHILD) 169452094c8aSAl Viro return err; 16954675ac39SAl Viro if (unlazy_walk(nd)) 169652094c8aSAl Viro return -ECHILD; 169752094c8aSAl Viro } 16984ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 169952094c8aSAl Viro } 170052094c8aSAl Viro 17019856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 17029856fa1bSAl Viro { 17039856fa1bSAl Viro if (type == LAST_DOTDOT) { 17049e6697e2SAl Viro if (!nd->root.mnt) 17059e6697e2SAl Viro set_root(nd); 17069856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 170770291aecSAl Viro return follow_dotdot_rcu(nd); 17089856fa1bSAl Viro } else 1709397d425dSEric W. Biederman return follow_dotdot(nd); 17109856fa1bSAl Viro } 17119856fa1bSAl Viro return 0; 17129856fa1bSAl Viro } 17139856fa1bSAl Viro 1714181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1715181548c0SAl Viro struct inode *inode, unsigned seq) 1716d63ff28fSAl Viro { 1717626de996SAl Viro int error; 17181cf2665bSAl Viro struct saved *last; 1719756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1720626de996SAl Viro path_to_nameidata(link, nd); 1721626de996SAl Viro return -ELOOP; 1722626de996SAl Viro } 1723bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1724cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1725cd179f44SAl Viro mntget(link->mnt); 17267973387aSAl Viro } 1727626de996SAl Viro error = nd_alloc_stack(nd); 1728626de996SAl Viro if (unlikely(error)) { 1729bc40aee0SAl Viro if (error == -ECHILD) { 1730ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1731ad1633a1SAl Viro drop_links(nd); 1732ad1633a1SAl Viro nd->depth = 0; 1733ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1734ad1633a1SAl Viro nd->path.mnt = NULL; 1735ad1633a1SAl Viro nd->path.dentry = NULL; 1736ad1633a1SAl Viro rcu_read_unlock(); 17374675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1738bc40aee0SAl Viro error = nd_alloc_stack(nd); 1739bc40aee0SAl Viro } 1740bc40aee0SAl Viro if (error) { 1741cd179f44SAl Viro path_put(link); 1742626de996SAl Viro return error; 1743626de996SAl Viro } 1744bc40aee0SAl Viro } 1745626de996SAl Viro 1746ab104923SAl Viro last = nd->stack + nd->depth++; 17471cf2665bSAl Viro last->link = *link; 1748fceef393SAl Viro clear_delayed_call(&last->done); 1749fceef393SAl Viro nd->link_inode = inode; 17500450b2d1SAl Viro last->seq = seq; 1751d63ff28fSAl Viro return 1; 1752d63ff28fSAl Viro } 1753d63ff28fSAl Viro 17548f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 175531d66bcdSAl Viro 17563ddcd056SLinus Torvalds /* 17573ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17583ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17593ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17603ddcd056SLinus Torvalds * for the common case. 17613ddcd056SLinus Torvalds */ 17628f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17638f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17643ddcd056SLinus Torvalds { 176531d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 176631d66bcdSAl Viro put_link(nd); 17678f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17688f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17698f64fb1cSAl Viro /* not a symlink or should not follow */ 17708f64fb1cSAl Viro path_to_nameidata(path, nd); 17718f64fb1cSAl Viro nd->inode = inode; 17728f64fb1cSAl Viro nd->seq = seq; 1773d63ff28fSAl Viro return 0; 17748f64fb1cSAl Viro } 1775a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1776a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17778f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1778a7f77542SAl Viro return -ECHILD; 1779a7f77542SAl Viro } 17808f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17813ddcd056SLinus Torvalds } 17823ddcd056SLinus Torvalds 17834693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1784ce57dfc1SAl Viro { 1785caa85634SAl Viro struct path path; 1786ce57dfc1SAl Viro struct inode *inode; 1787254cf582SAl Viro unsigned seq; 1788ce57dfc1SAl Viro int err; 1789ce57dfc1SAl Viro /* 1790ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1791ce57dfc1SAl Viro * to be able to know about the current root directory and 1792ce57dfc1SAl Viro * parent relationships. 1793ce57dfc1SAl Viro */ 17944693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17954693a547SAl Viro err = handle_dots(nd, nd->last_type); 17961c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17974693a547SAl Viro put_link(nd); 17984693a547SAl Viro return err; 17994693a547SAl Viro } 1800254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1801e9742b53SAl Viro if (unlikely(err <= 0)) { 1802697f514dSMiklos Szeredi if (err < 0) 1803f0a9ba70SAl Viro return err; 1804e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1805e3c13928SAl Viro nd->flags); 1806e3c13928SAl Viro if (IS_ERR(path.dentry)) 1807e3c13928SAl Viro return PTR_ERR(path.dentry); 18087500c38aSAl Viro 1809e3c13928SAl Viro path.mnt = nd->path.mnt; 1810e3c13928SAl Viro err = follow_managed(&path, nd); 1811e3c13928SAl Viro if (unlikely(err < 0)) 1812f0a9ba70SAl Viro return err; 1813697f514dSMiklos Szeredi 18147500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 18157500c38aSAl Viro path_to_nameidata(&path, nd); 18167500c38aSAl Viro return -ENOENT; 18177500c38aSAl Viro } 18187500c38aSAl Viro 1819254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1820d4565649SAl Viro inode = d_backing_inode(path.dentry); 1821766c4cbfSAl Viro } 1822697f514dSMiklos Szeredi 18238f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1824ce57dfc1SAl Viro } 1825ce57dfc1SAl Viro 18261da177e4SLinus Torvalds /* 1827bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1828bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1829bfcfaa77SLinus Torvalds * 1830bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1831bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1832bfcfaa77SLinus Torvalds * fast. 1833bfcfaa77SLinus Torvalds * 1834bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1835bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1836bfcfaa77SLinus Torvalds * crossing operation. 1837bfcfaa77SLinus Torvalds * 1838bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1839bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1840bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1841bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1842bfcfaa77SLinus Torvalds */ 1843bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1844bfcfaa77SLinus Torvalds 1845f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1846bfcfaa77SLinus Torvalds 1847468a9428SGeorge Spelvin #ifdef HASH_MIX 1848bfcfaa77SLinus Torvalds 1849468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1850468a9428SGeorge Spelvin 1851468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18522a18da7aSGeorge Spelvin /* 18532a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18542a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18552a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18562a18da7aSGeorge Spelvin * and no temporaries. 18572a18da7aSGeorge Spelvin * 18582a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18592a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18602a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18612a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18622a18da7aSGeorge Spelvin * 18632a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18642a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18652a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18662a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18672a18da7aSGeorge Spelvin * 18682a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18692a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18702a18da7aSGeorge Spelvin * toggling any given output bit. 18712a18da7aSGeorge Spelvin * 18722a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18732a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18742a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18752a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18762a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18772a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18782a18da7aSGeorge Spelvin * Perfect: 8192 258048 18792a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18802a18da7aSGeorge Spelvin */ 18812a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18822a18da7aSGeorge Spelvin ( x ^= (a), \ 18832a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18842a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18852a18da7aSGeorge Spelvin y *= 9 ) 1886bfcfaa77SLinus Torvalds 18870fed3ac8SGeorge Spelvin /* 18882a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18892a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18902a18da7aSGeorge Spelvin * work done before the hash value is used. 18910fed3ac8SGeorge Spelvin */ 18922a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18930fed3ac8SGeorge Spelvin { 18942a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18952a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18962a18da7aSGeorge Spelvin return y >> 32; 18970fed3ac8SGeorge Spelvin } 18980fed3ac8SGeorge Spelvin 1899bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1900bfcfaa77SLinus Torvalds 19012a18da7aSGeorge Spelvin /* 19022a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19032a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19042a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19052a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19062a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19072a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19082a18da7aSGeorge Spelvin * Perfect: 2048 31744 19092a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19102a18da7aSGeorge Spelvin */ 19112a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19122a18da7aSGeorge Spelvin ( x ^= (a), \ 19132a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19142a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19152a18da7aSGeorge Spelvin y *= 9 ) 1916bfcfaa77SLinus Torvalds 19172a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19180fed3ac8SGeorge Spelvin { 19192a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19202a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19210fed3ac8SGeorge Spelvin } 19220fed3ac8SGeorge Spelvin 1923bfcfaa77SLinus Torvalds #endif 1924bfcfaa77SLinus Torvalds 19252a18da7aSGeorge Spelvin /* 19262a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19272a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19282a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19292a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19302a18da7aSGeorge Spelvin * finds the delimiter after the name. 19312a18da7aSGeorge Spelvin */ 19328387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1933bfcfaa77SLinus Torvalds { 19348387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1935bfcfaa77SLinus Torvalds 1936bfcfaa77SLinus Torvalds for (;;) { 1937fcfd2fbfSGeorge Spelvin if (!len) 1938fcfd2fbfSGeorge Spelvin goto done; 1939e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1940bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1941bfcfaa77SLinus Torvalds break; 19422a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1943bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1944bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1945bfcfaa77SLinus Torvalds } 19462a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1947bfcfaa77SLinus Torvalds done: 19482a18da7aSGeorge Spelvin return fold_hash(x, y); 1949bfcfaa77SLinus Torvalds } 1950bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1951bfcfaa77SLinus Torvalds 1952fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19538387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1954fcfd2fbfSGeorge Spelvin { 19558387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19568387ff25SLinus Torvalds unsigned long adata, mask, len; 1957fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1958fcfd2fbfSGeorge Spelvin 19598387ff25SLinus Torvalds len = 0; 19608387ff25SLinus Torvalds goto inside; 19618387ff25SLinus Torvalds 1962fcfd2fbfSGeorge Spelvin do { 19632a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1964fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19658387ff25SLinus Torvalds inside: 1966fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1967fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1968fcfd2fbfSGeorge Spelvin 1969fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1970fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19712a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1972fcfd2fbfSGeorge Spelvin 19732a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1974fcfd2fbfSGeorge Spelvin } 1975fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1976fcfd2fbfSGeorge Spelvin 1977bfcfaa77SLinus Torvalds /* 1978bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1979d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1980bfcfaa77SLinus Torvalds */ 19818387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1982bfcfaa77SLinus Torvalds { 19838387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19848387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 198536126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1986bfcfaa77SLinus Torvalds 19878387ff25SLinus Torvalds len = 0; 19888387ff25SLinus Torvalds goto inside; 19898387ff25SLinus Torvalds 1990bfcfaa77SLinus Torvalds do { 19912a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1992bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19938387ff25SLinus Torvalds inside: 1994e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 199536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 199636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1997bfcfaa77SLinus Torvalds 199836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 199936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 200036126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20012a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 200236126f8fSLinus Torvalds 20032a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2004bfcfaa77SLinus Torvalds } 2005bfcfaa77SLinus Torvalds 20062a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2007bfcfaa77SLinus Torvalds 2008fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20098387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20100145acc2SLinus Torvalds { 20118387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20120145acc2SLinus Torvalds while (len--) 2013fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20140145acc2SLinus Torvalds return end_name_hash(hash); 20150145acc2SLinus Torvalds } 2016ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20170145acc2SLinus Torvalds 2018fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20198387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2020fcfd2fbfSGeorge Spelvin { 20218387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2022fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2023fcfd2fbfSGeorge Spelvin 2024fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2025e0ab7af9SGeorge Spelvin while (c) { 2026fcfd2fbfSGeorge Spelvin len++; 2027fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2028fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2029e0ab7af9SGeorge Spelvin } 2030fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2031fcfd2fbfSGeorge Spelvin } 2032f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2033fcfd2fbfSGeorge Spelvin 20343ddcd056SLinus Torvalds /* 2035200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2036200e9ef7SLinus Torvalds * one character. 2037200e9ef7SLinus Torvalds */ 20388387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2039200e9ef7SLinus Torvalds { 20408387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2041200e9ef7SLinus Torvalds unsigned long len = 0, c; 2042200e9ef7SLinus Torvalds 2043200e9ef7SLinus Torvalds c = (unsigned char)*name; 2044200e9ef7SLinus Torvalds do { 2045200e9ef7SLinus Torvalds len++; 2046200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2047200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2048200e9ef7SLinus Torvalds } while (c && c != '/'); 2049d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2050200e9ef7SLinus Torvalds } 2051200e9ef7SLinus Torvalds 2052bfcfaa77SLinus Torvalds #endif 2053bfcfaa77SLinus Torvalds 2054200e9ef7SLinus Torvalds /* 20551da177e4SLinus Torvalds * Name resolution. 2056ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2057ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20581da177e4SLinus Torvalds * 2059ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2060ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20611da177e4SLinus Torvalds */ 20626de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20631da177e4SLinus Torvalds { 20641da177e4SLinus Torvalds int err; 20651da177e4SLinus Torvalds 20669b5858e9SAl Viro if (IS_ERR(name)) 20679b5858e9SAl Viro return PTR_ERR(name); 20681da177e4SLinus Torvalds while (*name=='/') 20691da177e4SLinus Torvalds name++; 20701da177e4SLinus Torvalds if (!*name) 20719e18f10aSAl Viro return 0; 20721da177e4SLinus Torvalds 20731da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20741da177e4SLinus Torvalds for(;;) { 2075d6bb3e90SLinus Torvalds u64 hash_len; 2076fe479a58SAl Viro int type; 20771da177e4SLinus Torvalds 207852094c8aSAl Viro err = may_lookup(nd); 20791da177e4SLinus Torvalds if (err) 20803595e234SAl Viro return err; 20811da177e4SLinus Torvalds 20828387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20831da177e4SLinus Torvalds 2084fe479a58SAl Viro type = LAST_NORM; 2085d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2086fe479a58SAl Viro case 2: 2087200e9ef7SLinus Torvalds if (name[1] == '.') { 2088fe479a58SAl Viro type = LAST_DOTDOT; 208916c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 209016c2cd71SAl Viro } 2091fe479a58SAl Viro break; 2092fe479a58SAl Viro case 1: 2093fe479a58SAl Viro type = LAST_DOT; 2094fe479a58SAl Viro } 20955a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20965a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 209716c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20985a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2099a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2100da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21015a202bcdSAl Viro if (err < 0) 21023595e234SAl Viro return err; 2103d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2104d6bb3e90SLinus Torvalds name = this.name; 21055a202bcdSAl Viro } 21065a202bcdSAl Viro } 2107fe479a58SAl Viro 2108d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2109d6bb3e90SLinus Torvalds nd->last.name = name; 21105f4a6a69SAl Viro nd->last_type = type; 21115f4a6a69SAl Viro 2112d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2113d6bb3e90SLinus Torvalds if (!*name) 2114bdf6cbf1SAl Viro goto OK; 2115200e9ef7SLinus Torvalds /* 2116200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2117200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2118200e9ef7SLinus Torvalds */ 2119200e9ef7SLinus Torvalds do { 2120d6bb3e90SLinus Torvalds name++; 2121d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21228620c238SAl Viro if (unlikely(!*name)) { 21238620c238SAl Viro OK: 2124368ee9baSAl Viro /* pathname body, done */ 21258620c238SAl Viro if (!nd->depth) 21268620c238SAl Viro return 0; 21278620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2128368ee9baSAl Viro /* trailing symlink, done */ 21298620c238SAl Viro if (!name) 21308620c238SAl Viro return 0; 21318620c238SAl Viro /* last component of nested symlink */ 21328f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 21331c4ff1a8SAl Viro } else { 21341c4ff1a8SAl Viro /* not the last component */ 21358f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 21368620c238SAl Viro } 2137ce57dfc1SAl Viro if (err < 0) 21383595e234SAl Viro return err; 2139fe479a58SAl Viro 2140ce57dfc1SAl Viro if (err) { 2141626de996SAl Viro const char *s = get_link(nd); 21425a460275SAl Viro 2143a1c83681SViresh Kumar if (IS_ERR(s)) 21443595e234SAl Viro return PTR_ERR(s); 2145172a39a0SAl Viro err = 0; 214612b09578SAl Viro if (unlikely(!s)) { 214712b09578SAl Viro /* jumped */ 2148b9ff4429SAl Viro put_link(nd); 214912b09578SAl Viro } else { 2150071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 215132cd7468SAl Viro name = s; 21529e18f10aSAl Viro continue; 215348c8b0c5SAl Viro } 215431e6b01fSNick Piggin } 215597242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 215697242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21574675ac39SAl Viro if (unlazy_walk(nd)) 215897242f99SAl Viro return -ECHILD; 215997242f99SAl Viro } 21603595e234SAl Viro return -ENOTDIR; 21615f4a6a69SAl Viro } 2162ce57dfc1SAl Viro } 216397242f99SAl Viro } 21641da177e4SLinus Torvalds 2165edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2166c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 216731e6b01fSNick Piggin { 2168c8a53ee5SAl Viro const char *s = nd->name->name; 216931e6b01fSNick Piggin 2170c0eb027eSLinus Torvalds if (!*s) 2171c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2172edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2173edc2b1daSAl Viro rcu_read_lock(); 2174c0eb027eSLinus Torvalds 217531e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2176980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 217731e6b01fSNick Piggin nd->depth = 0; 21785b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2179b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2180b18825a7SDavid Howells struct inode *inode = root->d_inode; 218193893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2182368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21835b6ca027SAl Viro nd->path = nd->root; 21845b6ca027SAl Viro nd->inode = inode; 21855b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21865b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21878f47a016SAl Viro nd->root_seq = nd->seq; 218848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21895b6ca027SAl Viro } else { 21905b6ca027SAl Viro path_get(&nd->path); 21915b6ca027SAl Viro } 2192368ee9baSAl Viro return s; 21935b6ca027SAl Viro } 21945b6ca027SAl Viro 219531e6b01fSNick Piggin nd->root.mnt = NULL; 2196248fb5b9SAl Viro nd->path.mnt = NULL; 2197248fb5b9SAl Viro nd->path.dentry = NULL; 219831e6b01fSNick Piggin 219948a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2200fd2f7cb5SAl Viro if (*s == '/') { 2201e41f7d4eSAl Viro set_root(nd); 2202248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2203ef55d917SAl Viro return s; 2204ef55d917SAl Viro return ERR_PTR(-ECHILD); 2205c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2206e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 220731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2208c28cc364SNick Piggin unsigned seq; 220931e6b01fSNick Piggin 2210c28cc364SNick Piggin do { 2211c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 221231e6b01fSNick Piggin nd->path = fs->pwd; 2213ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2214c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2215c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2216e41f7d4eSAl Viro } else { 2217e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2218ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2219e41f7d4eSAl Viro } 2220ef55d917SAl Viro return s; 222131e6b01fSNick Piggin } else { 2222582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2223c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 222431e6b01fSNick Piggin struct dentry *dentry; 222531e6b01fSNick Piggin 22262903ff01SAl Viro if (!f.file) 2227368ee9baSAl Viro return ERR_PTR(-EBADF); 222831e6b01fSNick Piggin 22292903ff01SAl Viro dentry = f.file->f_path.dentry; 223031e6b01fSNick Piggin 2231edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22322903ff01SAl Viro fdput(f); 2233368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2234f52e0c11SAl Viro } 22352903ff01SAl Viro 22362903ff01SAl Viro nd->path = f.file->f_path; 2237e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 223834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 223934a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22405590ff0dSUlrich Drepper } else { 22412903ff01SAl Viro path_get(&nd->path); 224234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22431da177e4SLinus Torvalds } 224434a26b99SAl Viro fdput(f); 2245368ee9baSAl Viro return s; 2246e41f7d4eSAl Viro } 22479b4a9b14SAl Viro } 22489b4a9b14SAl Viro 22493bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 225095fa25d9SAl Viro { 225195fa25d9SAl Viro const char *s; 2252fec2fa24SAl Viro int error = may_follow_link(nd); 2253deb106c6SAl Viro if (unlikely(error)) 22543bdba28bSAl Viro return ERR_PTR(error); 225595fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2256fab51e8aSAl Viro nd->stack[0].name = NULL; 22573b2e7f75SAl Viro s = get_link(nd); 2258deb106c6SAl Viro return s ? s : ""; 225995fa25d9SAl Viro } 226095fa25d9SAl Viro 2261caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2262bd92d7feSAl Viro { 2263bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2264bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2265bd92d7feSAl Viro 2266bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22671c4ff1a8SAl Viro return walk_component(nd, 0); 2268bd92d7feSAl Viro } 2269bd92d7feSAl Viro 22704f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22714f757f3cSAl Viro { 22724f757f3cSAl Viro struct path path = nd->path; 22734f757f3cSAl Viro struct inode *inode = nd->inode; 22744f757f3cSAl Viro unsigned seq = nd->seq; 22754f757f3cSAl Viro int err; 22764f757f3cSAl Viro 22774f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22784f757f3cSAl Viro /* 22794f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22804f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22814f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22824f757f3cSAl Viro */ 22834f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22844f757f3cSAl Viro return -ECHILD; 22854f757f3cSAl Viro } else { 22864f757f3cSAl Viro dget(path.dentry); 22874f757f3cSAl Viro err = follow_managed(&path, nd); 22884f757f3cSAl Viro if (unlikely(err < 0)) 22894f757f3cSAl Viro return err; 22904f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22914f757f3cSAl Viro seq = 0; 22924f757f3cSAl Viro } 22934f757f3cSAl Viro path_to_nameidata(&path, nd); 22944f757f3cSAl Viro nd->inode = inode; 22954f757f3cSAl Viro nd->seq = seq; 22964f757f3cSAl Viro return 0; 22974f757f3cSAl Viro } 22984f757f3cSAl Viro 22999b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2300c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23019b4a9b14SAl Viro { 2302c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2303bd92d7feSAl Viro int err; 230431e6b01fSNick Piggin 23059b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23064f757f3cSAl Viro err = handle_lookup_down(nd); 23075f336e72SAl Viro if (unlikely(err < 0)) 23085f336e72SAl Viro s = ERR_PTR(err); 23094f757f3cSAl Viro } 23104f757f3cSAl Viro 23113bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 23123bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 23133bdba28bSAl Viro s = trailing_symlink(nd); 2314bd92d7feSAl Viro } 23159f1fafeeSAl Viro if (!err) 23169f1fafeeSAl Viro err = complete_walk(nd); 2317bd92d7feSAl Viro 2318deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2319deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2320bd23a539SAl Viro err = -ENOTDIR; 2321625b6d10SAl Viro if (!err) { 2322625b6d10SAl Viro *path = nd->path; 2323625b6d10SAl Viro nd->path.mnt = NULL; 2324625b6d10SAl Viro nd->path.dentry = NULL; 2325625b6d10SAl Viro } 2326deb106c6SAl Viro terminate_walk(nd); 2327bd92d7feSAl Viro return err; 232831e6b01fSNick Piggin } 232931e6b01fSNick Piggin 233031d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23319ad1aaa6SAl Viro struct path *path, struct path *root) 2332873f1eedSJeff Layton { 2333894bc8c4SAl Viro int retval; 23349883d185SAl Viro struct nameidata nd; 2335abc9f5beSAl Viro if (IS_ERR(name)) 2336abc9f5beSAl Viro return PTR_ERR(name); 23379ad1aaa6SAl Viro if (unlikely(root)) { 23389ad1aaa6SAl Viro nd.root = *root; 23399ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23409ad1aaa6SAl Viro } 23419883d185SAl Viro set_nameidata(&nd, dfd, name); 2342c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2343873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2344c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2345873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2346c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2347873f1eedSJeff Layton 2348873f1eedSJeff Layton if (likely(!retval)) 2349ff0ebee2SAl Viro audit_inode(name, path->dentry, 0); 23509883d185SAl Viro restore_nameidata(); 2351e4bd1c1aSAl Viro putname(name); 2352873f1eedSJeff Layton return retval; 2353873f1eedSJeff Layton } 2354873f1eedSJeff Layton 23558bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2356c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2357391172c4SAl Viro struct path *parent) 23588bcb77faSAl Viro { 2359c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23609b5858e9SAl Viro int err = link_path_walk(s, nd); 23618bcb77faSAl Viro if (!err) 23628bcb77faSAl Viro err = complete_walk(nd); 2363391172c4SAl Viro if (!err) { 2364391172c4SAl Viro *parent = nd->path; 2365391172c4SAl Viro nd->path.mnt = NULL; 2366391172c4SAl Viro nd->path.dentry = NULL; 2367391172c4SAl Viro } 2368deb106c6SAl Viro terminate_walk(nd); 23698bcb77faSAl Viro return err; 23708bcb77faSAl Viro } 23718bcb77faSAl Viro 23725c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2373391172c4SAl Viro unsigned int flags, struct path *parent, 2374391172c4SAl Viro struct qstr *last, int *type) 23758bcb77faSAl Viro { 23768bcb77faSAl Viro int retval; 23779883d185SAl Viro struct nameidata nd; 23788bcb77faSAl Viro 23795c31b6ceSAl Viro if (IS_ERR(name)) 23805c31b6ceSAl Viro return name; 23819883d185SAl Viro set_nameidata(&nd, dfd, name); 2382c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23838bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2384c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23858bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2386c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2387391172c4SAl Viro if (likely(!retval)) { 2388391172c4SAl Viro *last = nd.last; 2389391172c4SAl Viro *type = nd.last_type; 2390c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 23915c31b6ceSAl Viro } else { 23925c31b6ceSAl Viro putname(name); 23935c31b6ceSAl Viro name = ERR_PTR(retval); 2394391172c4SAl Viro } 23959883d185SAl Viro restore_nameidata(); 23965c31b6ceSAl Viro return name; 23978bcb77faSAl Viro } 23988bcb77faSAl Viro 239979714f72SAl Viro /* does lookup, returns the object with parent locked */ 240079714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24015590ff0dSUlrich Drepper { 24025c31b6ceSAl Viro struct filename *filename; 24035c31b6ceSAl Viro struct dentry *d; 2404391172c4SAl Viro struct qstr last; 2405391172c4SAl Viro int type; 240651689104SPaul Moore 24075c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24085c31b6ceSAl Viro &last, &type); 240951689104SPaul Moore if (IS_ERR(filename)) 241051689104SPaul Moore return ERR_CAST(filename); 24115c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2412391172c4SAl Viro path_put(path); 24135c31b6ceSAl Viro putname(filename); 24145c31b6ceSAl Viro return ERR_PTR(-EINVAL); 241579714f72SAl Viro } 24165955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2417391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 241879714f72SAl Viro if (IS_ERR(d)) { 24195955102cSAl Viro inode_unlock(path->dentry->d_inode); 2420391172c4SAl Viro path_put(path); 242179714f72SAl Viro } 242251689104SPaul Moore putname(filename); 242379714f72SAl Viro return d; 24245590ff0dSUlrich Drepper } 24255590ff0dSUlrich Drepper 2426d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2427d1811465SAl Viro { 2428abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2429abc9f5beSAl Viro flags, path, NULL); 2430d1811465SAl Viro } 24314d359507SAl Viro EXPORT_SYMBOL(kern_path); 2432d1811465SAl Viro 243316f18200SJosef 'Jeff' Sipek /** 243416f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 243516f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 243616f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 243716f18200SJosef 'Jeff' Sipek * @name: pointer to file name 243816f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2439e0a01249SAl Viro * @path: pointer to struct path to fill 244016f18200SJosef 'Jeff' Sipek */ 244116f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 244216f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2443e0a01249SAl Viro struct path *path) 244416f18200SJosef 'Jeff' Sipek { 24459ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24469ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2447abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2448abc9f5beSAl Viro flags , path, &root); 244916f18200SJosef 'Jeff' Sipek } 24504d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 245116f18200SJosef 'Jeff' Sipek 24523c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24533c95f0dcSAl Viro int len, struct qstr *this) 24543c95f0dcSAl Viro { 24553c95f0dcSAl Viro this->name = name; 24563c95f0dcSAl Viro this->len = len; 24573c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24583c95f0dcSAl Viro if (!len) 24593c95f0dcSAl Viro return -EACCES; 24603c95f0dcSAl Viro 24613c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24623c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24633c95f0dcSAl Viro return -EACCES; 24643c95f0dcSAl Viro } 24653c95f0dcSAl Viro 24663c95f0dcSAl Viro while (len--) { 24673c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24683c95f0dcSAl Viro if (c == '/' || c == '\0') 24693c95f0dcSAl Viro return -EACCES; 24703c95f0dcSAl Viro } 24713c95f0dcSAl Viro /* 24723c95f0dcSAl Viro * See if the low-level filesystem might want 24733c95f0dcSAl Viro * to use its own hash.. 24743c95f0dcSAl Viro */ 24753c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24763c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24773c95f0dcSAl Viro if (err < 0) 24783c95f0dcSAl Viro return err; 24793c95f0dcSAl Viro } 24803c95f0dcSAl Viro 24813c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24823c95f0dcSAl Viro } 24833c95f0dcSAl Viro 2484eead1911SChristoph Hellwig /** 24850da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 24860da0b7fdSDavid Howells * @name: pathname component to lookup 24870da0b7fdSDavid Howells * @base: base directory to lookup from 24880da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 24890da0b7fdSDavid Howells * 24900da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 24910da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 24920da0b7fdSDavid Howells * 24930da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 24940da0b7fdSDavid Howells * not be called by generic code. 24950da0b7fdSDavid Howells * 24960da0b7fdSDavid Howells * The caller must hold base->i_mutex. 24970da0b7fdSDavid Howells */ 24980da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 24990da0b7fdSDavid Howells { 25000da0b7fdSDavid Howells struct qstr this; 25010da0b7fdSDavid Howells int err; 25020da0b7fdSDavid Howells 25030da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25040da0b7fdSDavid Howells 25050da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25060da0b7fdSDavid Howells if (err) 25070da0b7fdSDavid Howells return ERR_PTR(err); 25080da0b7fdSDavid Howells 25090da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25100da0b7fdSDavid Howells } 25110da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25120da0b7fdSDavid Howells 25130da0b7fdSDavid Howells /** 2514a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2515eead1911SChristoph Hellwig * @name: pathname component to lookup 2516eead1911SChristoph Hellwig * @base: base directory to lookup from 2517eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2518eead1911SChristoph Hellwig * 2519a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25209e7543e9SAl Viro * not be called by generic code. 2521bbddca8eSNeilBrown * 2522bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2523eead1911SChristoph Hellwig */ 2524057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2525057f6c01SJames Morris { 25268613a209SAl Viro struct dentry *dentry; 2527057f6c01SJames Morris struct qstr this; 2528cda309deSMiklos Szeredi int err; 2529057f6c01SJames Morris 25305955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25312f9092e1SDavid Woodhouse 25323c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2533cda309deSMiklos Szeredi if (err) 2534cda309deSMiklos Szeredi return ERR_PTR(err); 2535cda309deSMiklos Szeredi 25368613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25378613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2538057f6c01SJames Morris } 25394d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2540057f6c01SJames Morris 2541bbddca8eSNeilBrown /** 2542bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2543bbddca8eSNeilBrown * @name: pathname component to lookup 2544bbddca8eSNeilBrown * @base: base directory to lookup from 2545bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2546bbddca8eSNeilBrown * 2547bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2548bbddca8eSNeilBrown * not be called by generic code. 2549bbddca8eSNeilBrown * 2550bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2551bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2552bbddca8eSNeilBrown */ 2553bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2554bbddca8eSNeilBrown struct dentry *base, int len) 2555bbddca8eSNeilBrown { 2556bbddca8eSNeilBrown struct qstr this; 2557bbddca8eSNeilBrown int err; 255820d00ee8SLinus Torvalds struct dentry *ret; 2559bbddca8eSNeilBrown 25603c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2561bbddca8eSNeilBrown if (err) 2562bbddca8eSNeilBrown return ERR_PTR(err); 2563bbddca8eSNeilBrown 256420d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 256520d00ee8SLinus Torvalds if (!ret) 256620d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 256720d00ee8SLinus Torvalds return ret; 2568bbddca8eSNeilBrown } 2569bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2570bbddca8eSNeilBrown 2571eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2572eedf265aSEric W. Biederman int path_pts(struct path *path) 2573eedf265aSEric W. Biederman { 2574eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2575eedf265aSEric W. Biederman * the input path. 2576eedf265aSEric W. Biederman */ 2577eedf265aSEric W. Biederman struct dentry *child, *parent; 2578eedf265aSEric W. Biederman struct qstr this; 2579eedf265aSEric W. Biederman int ret; 2580eedf265aSEric W. Biederman 2581eedf265aSEric W. Biederman ret = path_parent_directory(path); 2582eedf265aSEric W. Biederman if (ret) 2583eedf265aSEric W. Biederman return ret; 2584eedf265aSEric W. Biederman 2585eedf265aSEric W. Biederman parent = path->dentry; 2586eedf265aSEric W. Biederman this.name = "pts"; 2587eedf265aSEric W. Biederman this.len = 3; 2588eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2589eedf265aSEric W. Biederman if (!child) 2590eedf265aSEric W. Biederman return -ENOENT; 2591eedf265aSEric W. Biederman 2592eedf265aSEric W. Biederman path->dentry = child; 2593eedf265aSEric W. Biederman dput(parent); 2594eedf265aSEric W. Biederman follow_mount(path); 2595eedf265aSEric W. Biederman return 0; 2596eedf265aSEric W. Biederman } 2597eedf265aSEric W. Biederman #endif 2598eedf265aSEric W. Biederman 25991fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26001fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26011da177e4SLinus Torvalds { 2602abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2603abc9f5beSAl Viro flags, path, NULL); 26041da177e4SLinus Torvalds } 2605b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26061fa1e7f6SAndy Whitcroft 26078033426eSJeff Layton /** 2608197df04cSAl Viro * mountpoint_last - look up last component for umount 26098033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 26108033426eSJeff Layton * 26118033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 26128033426eSJeff Layton * need to resolve the path without doing any revalidation. 26138033426eSJeff Layton * 26148033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 26158033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 26168033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 26178033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 26188033426eSJeff Layton * bogus and it doesn't exist. 26198033426eSJeff Layton * 26208033426eSJeff Layton * Returns: 26218033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2622ba8f4613SAl Viro * lookup found a negative dentry. 26238033426eSJeff Layton * 2624ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2625ba8f4613SAl Viro * symlink that needs to be followed. 26268033426eSJeff Layton * 26278033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2628ba8f4613SAl Viro * that needs to be followed. 26298033426eSJeff Layton */ 26308033426eSJeff Layton static int 2631ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 26328033426eSJeff Layton { 26338033426eSJeff Layton int error = 0; 26348033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2635ba8f4613SAl Viro struct path path; 26368033426eSJeff Layton 263735759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 263835759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26394675ac39SAl Viro if (unlazy_walk(nd)) 2640deb106c6SAl Viro return -ECHILD; 26418033426eSJeff Layton } 26428033426eSJeff Layton 26438033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26448033426eSJeff Layton 26458033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26468033426eSJeff Layton error = handle_dots(nd, nd->last_type); 264735759521SAl Viro if (error) 2648deb106c6SAl Viro return error; 2649ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2650949a852eSAl Viro } else { 2651ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2652ba8f4613SAl Viro if (!path.dentry) { 26538033426eSJeff Layton /* 2654949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2655949a852eSAl Viro * cache, so that means that this dentry is probably 2656949a852eSAl Viro * a symlink or the path doesn't actually point 2657949a852eSAl Viro * to a mounted dentry. 26588033426eSJeff Layton */ 2659ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2660949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2661ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2662ba8f4613SAl Viro return PTR_ERR(path.dentry); 26638033426eSJeff Layton } 2664bcceeebaSDave Jones } 2665ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2666ba8f4613SAl Viro dput(path.dentry); 2667deb106c6SAl Viro return -ENOENT; 266835759521SAl Viro } 2669ba8f4613SAl Viro path.mnt = nd->path.mnt; 26708f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26718033426eSJeff Layton } 26728033426eSJeff Layton 26738033426eSJeff Layton /** 2674197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26752a78b857SMasanari Iida * @nd: lookup context 26768033426eSJeff Layton * @flags: lookup flags 2677c8a53ee5SAl Viro * @path: pointer to container for result 26788033426eSJeff Layton * 26798033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2680606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26818033426eSJeff Layton */ 26828033426eSJeff Layton static int 2683c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26848033426eSJeff Layton { 2685c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2686368ee9baSAl Viro int err; 26879b5858e9SAl Viro 26883bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2689ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26903bdba28bSAl Viro s = trailing_symlink(nd); 26913bdba28bSAl Viro } 2692ba8f4613SAl Viro if (!err) { 2693ba8f4613SAl Viro *path = nd->path; 2694ba8f4613SAl Viro nd->path.mnt = NULL; 2695ba8f4613SAl Viro nd->path.dentry = NULL; 2696ba8f4613SAl Viro follow_mount(path); 2697ba8f4613SAl Viro } 2698deb106c6SAl Viro terminate_walk(nd); 26998033426eSJeff Layton return err; 27008033426eSJeff Layton } 27018033426eSJeff Layton 27022d864651SAl Viro static int 2703668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 27042d864651SAl Viro unsigned int flags) 27052d864651SAl Viro { 27069883d185SAl Viro struct nameidata nd; 2707cbaab2dbSAl Viro int error; 2708668696dcSAl Viro if (IS_ERR(name)) 2709668696dcSAl Viro return PTR_ERR(name); 27109883d185SAl Viro set_nameidata(&nd, dfd, name); 2711c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 27122d864651SAl Viro if (unlikely(error == -ECHILD)) 2713c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 27142d864651SAl Viro if (unlikely(error == -ESTALE)) 2715c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 27162d864651SAl Viro if (likely(!error)) 2717c9b07eabSAl Viro audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); 27189883d185SAl Viro restore_nameidata(); 2719668696dcSAl Viro putname(name); 27202d864651SAl Viro return error; 27212d864651SAl Viro } 27222d864651SAl Viro 27238033426eSJeff Layton /** 2724197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27258033426eSJeff Layton * @dfd: directory file descriptor 27268033426eSJeff Layton * @name: pathname from userland 27278033426eSJeff Layton * @flags: lookup flags 27288033426eSJeff Layton * @path: pointer to container to hold result 27298033426eSJeff Layton * 27308033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27318033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27328033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27338033426eSJeff Layton * and avoid revalidating the last component. 27348033426eSJeff Layton * 27358033426eSJeff Layton * Returns 0 and populates "path" on success. 27368033426eSJeff Layton */ 27378033426eSJeff Layton int 2738197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27398033426eSJeff Layton struct path *path) 27408033426eSJeff Layton { 2741cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27428033426eSJeff Layton } 27438033426eSJeff Layton 27442d864651SAl Viro int 27452d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27462d864651SAl Viro unsigned int flags) 27472d864651SAl Viro { 2748cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27492d864651SAl Viro } 27502d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27512d864651SAl Viro 2752cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27531da177e4SLinus Torvalds { 27548e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2755da9592edSDavid Howells 27568e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27571da177e4SLinus Torvalds return 0; 27588e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27591da177e4SLinus Torvalds return 0; 276023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27611da177e4SLinus Torvalds } 2762cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27631da177e4SLinus Torvalds 27641da177e4SLinus Torvalds /* 27651da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27661da177e4SLinus Torvalds * whether the type of victim is right. 27671da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27681da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27691da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27701da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27711da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27721da177e4SLinus Torvalds * a. be owner of dir, or 27731da177e4SLinus Torvalds * b. be owner of victim, or 27741da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27751da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27761da177e4SLinus Torvalds * links pointing to it. 27770bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27780bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27790bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27800bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27810bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27821da177e4SLinus Torvalds * nfs_async_unlink(). 27831da177e4SLinus Torvalds */ 2784b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27851da177e4SLinus Torvalds { 278663afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27871da177e4SLinus Torvalds int error; 27881da177e4SLinus Torvalds 2789b18825a7SDavid Howells if (d_is_negative(victim)) 27901da177e4SLinus Torvalds return -ENOENT; 2791b18825a7SDavid Howells BUG_ON(!inode); 27921da177e4SLinus Torvalds 27931da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2794593d1ce8SEric W. Biederman 2795593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2796593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2797593d1ce8SEric W. Biederman return -EOVERFLOW; 2798593d1ce8SEric W. Biederman 27994fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 28001da177e4SLinus Torvalds 2801f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 28021da177e4SLinus Torvalds if (error) 28031da177e4SLinus Torvalds return error; 28041da177e4SLinus Torvalds if (IS_APPEND(dir)) 28051da177e4SLinus Torvalds return -EPERM; 2806b18825a7SDavid Howells 2807b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 28080bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 28091da177e4SLinus Torvalds return -EPERM; 28101da177e4SLinus Torvalds if (isdir) { 281144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 28121da177e4SLinus Torvalds return -ENOTDIR; 28131da177e4SLinus Torvalds if (IS_ROOT(victim)) 28141da177e4SLinus Torvalds return -EBUSY; 281544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 28161da177e4SLinus Torvalds return -EISDIR; 28171da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28181da177e4SLinus Torvalds return -ENOENT; 28191da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 28201da177e4SLinus Torvalds return -EBUSY; 28211da177e4SLinus Torvalds return 0; 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds 28241da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28251da177e4SLinus Torvalds * dir. 28261da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28271da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28281da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2829036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2830036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2831036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 28321da177e4SLinus Torvalds */ 2833a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28341da177e4SLinus Torvalds { 2835036d5236SEric W. Biederman struct user_namespace *s_user_ns; 283614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28371da177e4SLinus Torvalds if (child->d_inode) 28381da177e4SLinus Torvalds return -EEXIST; 28391da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28401da177e4SLinus Torvalds return -ENOENT; 2841036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2842036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2843036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2844036d5236SEric W. Biederman return -EOVERFLOW; 2845f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28461da177e4SLinus Torvalds } 28471da177e4SLinus Torvalds 28481da177e4SLinus Torvalds /* 28491da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28501da177e4SLinus Torvalds */ 28511da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28521da177e4SLinus Torvalds { 28531da177e4SLinus Torvalds struct dentry *p; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds if (p1 == p2) { 28565955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28571da177e4SLinus Torvalds return NULL; 28581da177e4SLinus Torvalds } 28591da177e4SLinus Torvalds 2860fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28611da177e4SLinus Torvalds 2862e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2863e2761a11SOGAWA Hirofumi if (p) { 28645955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28655955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28661da177e4SLinus Torvalds return p; 28671da177e4SLinus Torvalds } 28681da177e4SLinus Torvalds 2869e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2870e2761a11SOGAWA Hirofumi if (p) { 28715955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28725955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28731da177e4SLinus Torvalds return p; 28741da177e4SLinus Torvalds } 28751da177e4SLinus Torvalds 28765955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28775955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28781da177e4SLinus Torvalds return NULL; 28791da177e4SLinus Torvalds } 28804d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28811da177e4SLinus Torvalds 28821da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28831da177e4SLinus Torvalds { 28845955102cSAl Viro inode_unlock(p1->d_inode); 28851da177e4SLinus Torvalds if (p1 != p2) { 28865955102cSAl Viro inode_unlock(p2->d_inode); 2887fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28881da177e4SLinus Torvalds } 28891da177e4SLinus Torvalds } 28904d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28911da177e4SLinus Torvalds 28924acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2893312b63fbSAl Viro bool want_excl) 28941da177e4SLinus Torvalds { 2895a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28961da177e4SLinus Torvalds if (error) 28971da177e4SLinus Torvalds return error; 28981da177e4SLinus Torvalds 2899acfa4380SAl Viro if (!dir->i_op->create) 29001da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 29011da177e4SLinus Torvalds mode &= S_IALLUGO; 29021da177e4SLinus Torvalds mode |= S_IFREG; 29031da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 29041da177e4SLinus Torvalds if (error) 29051da177e4SLinus Torvalds return error; 2906312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2907a74574aaSStephen Smalley if (!error) 2908f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29091da177e4SLinus Torvalds return error; 29101da177e4SLinus Torvalds } 29114d359507SAl Viro EXPORT_SYMBOL(vfs_create); 29121da177e4SLinus Torvalds 29138e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 29148e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 29158e6c848eSAl Viro void *arg) 29168e6c848eSAl Viro { 29178e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 29188e6c848eSAl Viro int error = may_create(dir, dentry); 29198e6c848eSAl Viro if (error) 29208e6c848eSAl Viro return error; 29218e6c848eSAl Viro 29228e6c848eSAl Viro mode &= S_IALLUGO; 29238e6c848eSAl Viro mode |= S_IFREG; 29248e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 29258e6c848eSAl Viro if (error) 29268e6c848eSAl Viro return error; 29278e6c848eSAl Viro error = f(dentry, mode, arg); 29288e6c848eSAl Viro if (!error) 29298e6c848eSAl Viro fsnotify_create(dir, dentry); 29308e6c848eSAl Viro return error; 29318e6c848eSAl Viro } 29328e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 29338e6c848eSAl Viro 2934a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2935a2982cc9SEric W. Biederman { 2936a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2937a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2938a2982cc9SEric W. Biederman } 2939a2982cc9SEric W. Biederman 2940f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 29411da177e4SLinus Torvalds { 29423fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29431da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29441da177e4SLinus Torvalds int error; 29451da177e4SLinus Torvalds 29461da177e4SLinus Torvalds if (!inode) 29471da177e4SLinus Torvalds return -ENOENT; 29481da177e4SLinus Torvalds 2949c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2950c8fe8f30SChristoph Hellwig case S_IFLNK: 29511da177e4SLinus Torvalds return -ELOOP; 2952c8fe8f30SChristoph Hellwig case S_IFDIR: 2953c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29541da177e4SLinus Torvalds return -EISDIR; 2955c8fe8f30SChristoph Hellwig break; 2956c8fe8f30SChristoph Hellwig case S_IFBLK: 2957c8fe8f30SChristoph Hellwig case S_IFCHR: 2958a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29591da177e4SLinus Torvalds return -EACCES; 2960c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2961c8fe8f30SChristoph Hellwig case S_IFIFO: 2962c8fe8f30SChristoph Hellwig case S_IFSOCK: 29631da177e4SLinus Torvalds flag &= ~O_TRUNC; 2964c8fe8f30SChristoph Hellwig break; 29654a3fd211SDave Hansen } 2966b41572e9SDave Hansen 296762fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2968b41572e9SDave Hansen if (error) 2969b41572e9SDave Hansen return error; 29706146f0d5SMimi Zohar 29711da177e4SLinus Torvalds /* 29721da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29731da177e4SLinus Torvalds */ 29741da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29758737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29767715b521SAl Viro return -EPERM; 29771da177e4SLinus Torvalds if (flag & O_TRUNC) 29787715b521SAl Viro return -EPERM; 29791da177e4SLinus Torvalds } 29801da177e4SLinus Torvalds 29811da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29822e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29837715b521SAl Viro return -EPERM; 29841da177e4SLinus Torvalds 2985f3c7691eSJ. Bruce Fields return 0; 29867715b521SAl Viro } 29877715b521SAl Viro 2988e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29897715b521SAl Viro { 2990f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29917715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29927715b521SAl Viro int error = get_write_access(inode); 29931da177e4SLinus Torvalds if (error) 29947715b521SAl Viro return error; 29951da177e4SLinus Torvalds /* 29961da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29971da177e4SLinus Torvalds */ 2998d7a06983SJeff Layton error = locks_verify_locked(filp); 2999be6d3e56SKentaro Takeda if (!error) 3000ea0d3ab2STetsuo Handa error = security_path_truncate(path); 30011da177e4SLinus Torvalds if (!error) { 30027715b521SAl Viro error = do_truncate(path->dentry, 0, 3003d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 3004e1181ee6SJeff Layton filp); 30051da177e4SLinus Torvalds } 30061da177e4SLinus Torvalds put_write_access(inode); 3007acd0c935SMimi Zohar return error; 30081da177e4SLinus Torvalds } 30091da177e4SLinus Torvalds 3010d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 3011d57999e1SDave Hansen { 30128a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 30138a5e929dSAl Viro flag--; 3014d57999e1SDave Hansen return flag; 3015d57999e1SDave Hansen } 3016d57999e1SDave Hansen 3017d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 3018d18e9008SMiklos Szeredi { 30191328c727SSeth Forshee struct user_namespace *s_user_ns; 3020d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 3021d18e9008SMiklos Szeredi if (error) 3022d18e9008SMiklos Szeredi return error; 3023d18e9008SMiklos Szeredi 30241328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 30251328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 30261328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 30271328c727SSeth Forshee return -EOVERFLOW; 30281328c727SSeth Forshee 3029d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 3030d18e9008SMiklos Szeredi if (error) 3031d18e9008SMiklos Szeredi return error; 3032d18e9008SMiklos Szeredi 3033d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3034d18e9008SMiklos Szeredi } 3035d18e9008SMiklos Szeredi 30361acf0af9SDavid Howells /* 30371acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 30381acf0af9SDavid Howells * dentry. 30391acf0af9SDavid Howells * 30401acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 30411acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 30421acf0af9SDavid Howells * 304300a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 304400a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 304500a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 30461acf0af9SDavid Howells * 30471acf0af9SDavid Howells * Returns an error code otherwise. 30481acf0af9SDavid Howells */ 30492675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 305030d90494SAl Viro struct path *path, struct file *file, 3051015c3bbcSMiklos Szeredi const struct open_flags *op, 30523ec2eef1SAl Viro int open_flag, umode_t mode) 3053d18e9008SMiklos Szeredi { 3054d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3055d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3056d18e9008SMiklos Szeredi int error; 3057d18e9008SMiklos Szeredi 3058384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3059d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3060d18e9008SMiklos Szeredi 3061d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3062d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3063d18e9008SMiklos Szeredi 306430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 306530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30660fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 306744907d79SAl Viro open_to_namei_flags(open_flag), mode); 30686fbd0714SAl Viro d_lookup_done(dentry); 3069384f26e2SAl Viro if (!error) { 307064e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3071d18e9008SMiklos Szeredi /* 3072384f26e2SAl Viro * We didn't have the inode before the open, so check open 3073384f26e2SAl Viro * permission here. 3074d18e9008SMiklos Szeredi */ 3075384f26e2SAl Viro int acc_mode = op->acc_mode; 307673a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 307703da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 307803da633aSAl Viro fsnotify_create(dir, dentry); 307962fb4a15SAl Viro acc_mode = 0; 308003da633aSAl Viro } 30812675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3082384f26e2SAl Viro if (WARN_ON(error > 0)) 3083384f26e2SAl Viro error = -EINVAL; 308464e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3085d18e9008SMiklos Szeredi error = -EIO; 3086384f26e2SAl Viro } else { 3087d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3088d18e9008SMiklos Szeredi dput(dentry); 3089d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 309010c64ceaSAl Viro } 309173a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3092d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3093a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3094a01e718fSAl Viro error = -ENOENT; 3095a01e718fSAl Viro } else { 3096d18e9008SMiklos Szeredi path->dentry = dentry; 3097d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 309800a07c15SAl Viro return 0; 3099d18e9008SMiklos Szeredi } 3100d18e9008SMiklos Szeredi } 3101a01e718fSAl Viro } 3102d18e9008SMiklos Szeredi dput(dentry); 3103d18e9008SMiklos Szeredi return error; 3104d18e9008SMiklos Szeredi } 3105d18e9008SMiklos Szeredi 310631e6b01fSNick Piggin /* 31071acf0af9SDavid Howells * Look up and maybe create and open the last component. 3108d58ffd35SMiklos Szeredi * 310900a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3110d58ffd35SMiklos Szeredi * 311100a07c15SAl Viro * Returns 0 on success, that is, if 311200a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 311300a07c15SAl Viro * the file was not completely opened at this time, though lookups and 311400a07c15SAl Viro * creations were performed. 311500a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 311600a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 311700a07c15SAl Viro * hadn't been specified. 31181acf0af9SDavid Howells * 311900a07c15SAl Viro * An error code is returned on failure. 3120d58ffd35SMiklos Szeredi */ 31212675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 312230d90494SAl Viro struct file *file, 3123d58ffd35SMiklos Szeredi const struct open_flags *op, 31243ec2eef1SAl Viro bool got_write) 3125d58ffd35SMiklos Szeredi { 3126d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 312754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 31281643b43fSAl Viro int open_flag = op->open_flag; 3129d58ffd35SMiklos Szeredi struct dentry *dentry; 31301643b43fSAl Viro int error, create_error = 0; 31311643b43fSAl Viro umode_t mode = op->mode; 31326fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3133d58ffd35SMiklos Szeredi 3134ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3135ce8644fcSAl Viro return -ENOENT; 3136d58ffd35SMiklos Szeredi 313773a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 31386fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 31396fbd0714SAl Viro for (;;) { 31406fbd0714SAl Viro if (!dentry) { 31416fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3142d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31432675a4ebSAl Viro return PTR_ERR(dentry); 31446fbd0714SAl Viro } 31456fbd0714SAl Viro if (d_in_lookup(dentry)) 31466fbd0714SAl Viro break; 3147d58ffd35SMiklos Szeredi 31486fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31496fbd0714SAl Viro if (likely(error > 0)) 31506fbd0714SAl Viro break; 31516fbd0714SAl Viro if (error) 31526fbd0714SAl Viro goto out_dput; 31536fbd0714SAl Viro d_invalidate(dentry); 31546fbd0714SAl Viro dput(dentry); 31556fbd0714SAl Viro dentry = NULL; 31566fbd0714SAl Viro } 31576fbd0714SAl Viro if (dentry->d_inode) { 3158d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3159d18e9008SMiklos Szeredi goto out_no_open; 31606c51e513SAl Viro } 3161d18e9008SMiklos Szeredi 31621643b43fSAl Viro /* 31631643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31641643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31651643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31661643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31671643b43fSAl Viro * 31681643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31691643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31701643b43fSAl Viro */ 31711643b43fSAl Viro if (open_flag & O_CREAT) { 31721643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31731643b43fSAl Viro mode &= ~current_umask(); 31741643b43fSAl Viro if (unlikely(!got_write)) { 31751643b43fSAl Viro create_error = -EROFS; 31761643b43fSAl Viro open_flag &= ~O_CREAT; 31771643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31781643b43fSAl Viro goto no_open; 31791643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31801643b43fSAl Viro } else { 31811643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31821643b43fSAl Viro if (create_error) { 31831643b43fSAl Viro open_flag &= ~O_CREAT; 31841643b43fSAl Viro if (open_flag & O_EXCL) 31851643b43fSAl Viro goto no_open; 31861643b43fSAl Viro } 31871643b43fSAl Viro } 31881643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31891643b43fSAl Viro unlikely(!got_write)) { 31901643b43fSAl Viro /* 31911643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31921643b43fSAl Viro * back to lookup + open 31931643b43fSAl Viro */ 31941643b43fSAl Viro goto no_open; 3195d18e9008SMiklos Szeredi } 3196d18e9008SMiklos Szeredi 31971643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31981643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31993ec2eef1SAl Viro mode); 32001643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 32011643b43fSAl Viro error = create_error; 32021643b43fSAl Viro return error; 32031643b43fSAl Viro } 320454ef4872SMiklos Szeredi 32051643b43fSAl Viro no_open: 32066fbd0714SAl Viro if (d_in_lookup(dentry)) { 320712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 320812fa5e24SAl Viro nd->flags); 32096fbd0714SAl Viro d_lookup_done(dentry); 321012fa5e24SAl Viro if (unlikely(res)) { 321112fa5e24SAl Viro if (IS_ERR(res)) { 321212fa5e24SAl Viro error = PTR_ERR(res); 321312fa5e24SAl Viro goto out_dput; 321412fa5e24SAl Viro } 321512fa5e24SAl Viro dput(dentry); 321612fa5e24SAl Viro dentry = res; 321712fa5e24SAl Viro } 321854ef4872SMiklos Szeredi } 321954ef4872SMiklos Szeredi 3220d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 32211643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 322273a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3223ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3224ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3225ce8644fcSAl Viro error = -EACCES; 3226d58ffd35SMiklos Szeredi goto out_dput; 322764894cf8SAl Viro } 3228ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 32291643b43fSAl Viro open_flag & O_EXCL); 3230d58ffd35SMiklos Szeredi if (error) 3231d58ffd35SMiklos Szeredi goto out_dput; 3232ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3233d58ffd35SMiklos Szeredi } 32341643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 32351643b43fSAl Viro error = create_error; 3236d58ffd35SMiklos Szeredi goto out_dput; 3237d58ffd35SMiklos Szeredi } 3238d18e9008SMiklos Szeredi out_no_open: 3239d58ffd35SMiklos Szeredi path->dentry = dentry; 3240d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 324100a07c15SAl Viro return 0; 3242d58ffd35SMiklos Szeredi 3243d58ffd35SMiklos Szeredi out_dput: 3244d58ffd35SMiklos Szeredi dput(dentry); 32452675a4ebSAl Viro return error; 3246d58ffd35SMiklos Szeredi } 3247d58ffd35SMiklos Szeredi 3248d58ffd35SMiklos Szeredi /* 3249fe2d35ffSAl Viro * Handle the last step of open() 325031e6b01fSNick Piggin */ 3251896475d5SAl Viro static int do_last(struct nameidata *nd, 32523ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3253fb1cc555SAl Viro { 3254a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3255ca344a89SAl Viro int open_flag = op->open_flag; 325677d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 325764894cf8SAl Viro bool got_write = false; 3258bcda7652SAl Viro int acc_mode = op->acc_mode; 3259254cf582SAl Viro unsigned seq; 3260a1eb3315SMiklos Szeredi struct inode *inode; 3261896475d5SAl Viro struct path path; 326216c2cd71SAl Viro int error; 3263fb1cc555SAl Viro 3264c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3265c3e380b0SAl Viro nd->flags |= op->intent; 3266c3e380b0SAl Viro 3267bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3268fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3269deb106c6SAl Viro if (unlikely(error)) 32702675a4ebSAl Viro return error; 3271e83db167SMiklos Szeredi goto finish_open; 32721f36f774SAl Viro } 3273a2c36b45SAl Viro 3274ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3275fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3276fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3277fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3278254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3279e9742b53SAl Viro if (likely(error > 0)) 328071574865SMiklos Szeredi goto finish_lookup; 328171574865SMiklos Szeredi 3282ce57dfc1SAl Viro if (error < 0) 3283deb106c6SAl Viro return error; 3284a1eb3315SMiklos Szeredi 328537d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32866583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3287b6183df7SMiklos Szeredi } else { 3288fe2d35ffSAl Viro /* create side of things */ 3289a3fbbde7SAl Viro /* 3290b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3291b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3292b6183df7SMiklos Szeredi * about to look up 3293a3fbbde7SAl Viro */ 32949f1fafeeSAl Viro error = complete_walk(nd); 3295e8bb73dfSAl Viro if (error) 32962675a4ebSAl Viro return error; 3297fe2d35ffSAl Viro 3298c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32991f36f774SAl Viro /* trailing slashes? */ 3300deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3301deb106c6SAl Viro return -EISDIR; 3302b6183df7SMiklos Szeredi } 33031f36f774SAl Viro 33049cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 330564894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 330664894cf8SAl Viro if (!error) 330764894cf8SAl Viro got_write = true; 330864894cf8SAl Viro /* 330964894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 331064894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 331164894cf8SAl Viro * dropping this one anyway. 331264894cf8SAl Viro */ 331364894cf8SAl Viro } 33149cf843e3SAl Viro if (open_flag & O_CREAT) 33155955102cSAl Viro inode_lock(dir->d_inode); 33169cf843e3SAl Viro else 33179cf843e3SAl Viro inode_lock_shared(dir->d_inode); 33183ec2eef1SAl Viro error = lookup_open(nd, &path, file, op, got_write); 33199cf843e3SAl Viro if (open_flag & O_CREAT) 33205955102cSAl Viro inode_unlock(dir->d_inode); 33219cf843e3SAl Viro else 33229cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3323fb1cc555SAl Viro 33242675a4ebSAl Viro if (error) 3325d58ffd35SMiklos Szeredi goto out; 33266c0d46c4SAl Viro 332700a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 332873a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3329496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 333077d660a8SMiklos Szeredi will_truncate = false; 3331d18e9008SMiklos Szeredi 333276ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3333d18e9008SMiklos Szeredi goto opened; 3334d18e9008SMiklos Szeredi } 3335d18e9008SMiklos Szeredi 333673a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 33379b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3338ca344a89SAl Viro open_flag &= ~O_TRUNC; 333977d660a8SMiklos Szeredi will_truncate = false; 334062fb4a15SAl Viro acc_mode = 0; 3341896475d5SAl Viro path_to_nameidata(&path, nd); 3342e83db167SMiklos Szeredi goto finish_open_created; 3343fb1cc555SAl Viro } 3344fb1cc555SAl Viro 3345fb1cc555SAl Viro /* 3346d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3347d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3348d18e9008SMiklos Szeredi * necessary...) 3349d18e9008SMiklos Szeredi */ 335064894cf8SAl Viro if (got_write) { 3351d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 335264894cf8SAl Viro got_write = false; 3353d18e9008SMiklos Szeredi } 3354d18e9008SMiklos Szeredi 3355e6ec03a2SAl Viro error = follow_managed(&path, nd); 3356e6ec03a2SAl Viro if (unlikely(error < 0)) 3357e6ec03a2SAl Viro return error; 3358e6ec03a2SAl Viro 33596583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33606583fe22SAl Viro path_to_nameidata(&path, nd); 33616583fe22SAl Viro return -ENOENT; 33626583fe22SAl Viro } 33636583fe22SAl Viro 33646583fe22SAl Viro /* 33656583fe22SAl Viro * create/update audit record if it already exists. 33666583fe22SAl Viro */ 33676583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33686583fe22SAl Viro 3369deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3370deb106c6SAl Viro path_to_nameidata(&path, nd); 3371deb106c6SAl Viro return -EEXIST; 3372deb106c6SAl Viro } 3373fb1cc555SAl Viro 3374254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3375d4565649SAl Viro inode = d_backing_inode(path.dentry); 3376766c4cbfSAl Viro finish_lookup: 33778f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3378deb106c6SAl Viro if (unlikely(error)) 3379d63ff28fSAl Viro return error; 3380bc77daa7SAl Viro finish_open: 33818f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3382a3fbbde7SAl Viro error = complete_walk(nd); 3383fac7d191SAl Viro if (error) 33842675a4ebSAl Viro return error; 338576ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 338630aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3387fb1cc555SAl Viro error = -EISDIR; 338830aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 33892675a4ebSAl Viro goto out; 339030aba665SSalvatore Mesoraca error = may_create_in_sticky(dir, 339130aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 339230aba665SSalvatore Mesoraca if (unlikely(error)) 339330aba665SSalvatore Mesoraca goto out; 339430aba665SSalvatore Mesoraca } 3395af2f5542SMiklos Szeredi error = -ENOTDIR; 339644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33972675a4ebSAl Viro goto out; 33984bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 339977d660a8SMiklos Szeredi will_truncate = false; 34006c0d46c4SAl Viro 34010f9d1a10SAl Viro if (will_truncate) { 34020f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 34030f9d1a10SAl Viro if (error) 34042675a4ebSAl Viro goto out; 340564894cf8SAl Viro got_write = true; 34060f9d1a10SAl Viro } 3407e83db167SMiklos Szeredi finish_open_created: 3408bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3409ca344a89SAl Viro if (error) 34102675a4ebSAl Viro goto out; 3411aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3412ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3413fac7d191SAl Viro if (error) 3414015c3bbcSMiklos Szeredi goto out; 3415a8277b9bSMiklos Szeredi opened: 34166035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3417fe9ec829SAl Viro if (!error && will_truncate) 34182675a4ebSAl Viro error = handle_truncate(file); 3419ca344a89SAl Viro out: 3420c80567c8SAl Viro if (unlikely(error > 0)) { 3421c80567c8SAl Viro WARN_ON(1); 3422c80567c8SAl Viro error = -EINVAL; 3423c80567c8SAl Viro } 342464894cf8SAl Viro if (got_write) 34250f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 34262675a4ebSAl Viro return error; 3427fb1cc555SAl Viro } 3428fb1cc555SAl Viro 3429af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3430af7bd4dcSAmir Goldstein { 3431af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3432af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3433af7bd4dcSAmir Goldstein struct inode *inode; 3434af7bd4dcSAmir Goldstein int error; 3435af7bd4dcSAmir Goldstein 3436af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3437af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3438af7bd4dcSAmir Goldstein if (error) 3439af7bd4dcSAmir Goldstein goto out_err; 3440af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3441af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3442af7bd4dcSAmir Goldstein goto out_err; 3443af7bd4dcSAmir Goldstein error = -ENOMEM; 3444cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3445af7bd4dcSAmir Goldstein if (unlikely(!child)) 3446af7bd4dcSAmir Goldstein goto out_err; 3447af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3448af7bd4dcSAmir Goldstein if (error) 3449af7bd4dcSAmir Goldstein goto out_err; 3450af7bd4dcSAmir Goldstein error = -ENOENT; 3451af7bd4dcSAmir Goldstein inode = child->d_inode; 3452af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3453af7bd4dcSAmir Goldstein goto out_err; 3454af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3455af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3456af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3457af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3458af7bd4dcSAmir Goldstein } 3459fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3460af7bd4dcSAmir Goldstein return child; 3461af7bd4dcSAmir Goldstein 3462af7bd4dcSAmir Goldstein out_err: 3463af7bd4dcSAmir Goldstein dput(child); 3464af7bd4dcSAmir Goldstein return ERR_PTR(error); 3465af7bd4dcSAmir Goldstein } 3466af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3467af7bd4dcSAmir Goldstein 3468c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 346960545d0dSAl Viro const struct open_flags *op, 34703ec2eef1SAl Viro struct file *file) 347160545d0dSAl Viro { 3472625b6d10SAl Viro struct dentry *child; 3473625b6d10SAl Viro struct path path; 3474c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 347560545d0dSAl Viro if (unlikely(error)) 347660545d0dSAl Viro return error; 3477625b6d10SAl Viro error = mnt_want_write(path.mnt); 347860545d0dSAl Viro if (unlikely(error)) 347960545d0dSAl Viro goto out; 3480af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3481af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3482684e73beSHirofumi Nakagawa if (IS_ERR(child)) 348360545d0dSAl Viro goto out2; 3484625b6d10SAl Viro dput(path.dentry); 3485625b6d10SAl Viro path.dentry = child; 3486c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 348769a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 348862fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 348960545d0dSAl Viro if (error) 349060545d0dSAl Viro goto out2; 3491625b6d10SAl Viro file->f_path.mnt = path.mnt; 3492be12af3eSAl Viro error = finish_open(file, child, NULL); 349360545d0dSAl Viro out2: 3494625b6d10SAl Viro mnt_drop_write(path.mnt); 349560545d0dSAl Viro out: 3496625b6d10SAl Viro path_put(&path); 349760545d0dSAl Viro return error; 349860545d0dSAl Viro } 349960545d0dSAl Viro 35006ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 35016ac08709SAl Viro { 35026ac08709SAl Viro struct path path; 35036ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 35046ac08709SAl Viro if (!error) { 35056ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3506ae2bb293SAl Viro error = vfs_open(&path, file); 35076ac08709SAl Viro path_put(&path); 35086ac08709SAl Viro } 35096ac08709SAl Viro return error; 35106ac08709SAl Viro } 35116ac08709SAl Viro 3512c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3513c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 35141da177e4SLinus Torvalds { 351530d90494SAl Viro struct file *file; 351613aab428SAl Viro int error; 351731e6b01fSNick Piggin 3518ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 35191afc99beSAl Viro if (IS_ERR(file)) 35201afc99beSAl Viro return file; 352131e6b01fSNick Piggin 3522bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 35233ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 35245f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 35256ac08709SAl Viro error = do_o_path(nd, flags, file); 35265f336e72SAl Viro } else { 35275f336e72SAl Viro const char *s = path_init(nd, flags); 35283bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 35293ec2eef1SAl Viro (error = do_last(nd, file, op)) > 0) { 353073d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35313bdba28bSAl Viro s = trailing_symlink(nd); 35323bdba28bSAl Viro } 3533deb106c6SAl Viro terminate_walk(nd); 35345f336e72SAl Viro } 35357c1c01ecSAl Viro if (likely(!error)) { 3536aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 35377c1c01ecSAl Viro return file; 35387c1c01ecSAl Viro WARN_ON(1); 35397c1c01ecSAl Viro error = -EINVAL; 3540015c3bbcSMiklos Szeredi } 35417c1c01ecSAl Viro fput(file); 35422675a4ebSAl Viro if (error == -EOPENSTALE) { 35432675a4ebSAl Viro if (flags & LOOKUP_RCU) 35442675a4ebSAl Viro error = -ECHILD; 35452675a4ebSAl Viro else 35462675a4ebSAl Viro error = -ESTALE; 35472675a4ebSAl Viro } 35487c1c01ecSAl Viro return ERR_PTR(error); 3549de459215SKirill Korotaev } 35501da177e4SLinus Torvalds 3551669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3552f9652e10SAl Viro const struct open_flags *op) 355313aab428SAl Viro { 35549883d185SAl Viro struct nameidata nd; 3555f9652e10SAl Viro int flags = op->lookup_flags; 355613aab428SAl Viro struct file *filp; 355713aab428SAl Viro 35589883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3559c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 356013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3561c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 356213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3563c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35649883d185SAl Viro restore_nameidata(); 356513aab428SAl Viro return filp; 356613aab428SAl Viro } 356713aab428SAl Viro 356873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3569f9652e10SAl Viro const char *name, const struct open_flags *op) 357073d049a4SAl Viro { 35719883d185SAl Viro struct nameidata nd; 357273d049a4SAl Viro struct file *file; 357351689104SPaul Moore struct filename *filename; 3574f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 357573d049a4SAl Viro 357673d049a4SAl Viro nd.root.mnt = mnt; 357773d049a4SAl Viro nd.root.dentry = dentry; 357873d049a4SAl Viro 3579b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 358073d049a4SAl Viro return ERR_PTR(-ELOOP); 358173d049a4SAl Viro 358251689104SPaul Moore filename = getname_kernel(name); 3583a1c83681SViresh Kumar if (IS_ERR(filename)) 358451689104SPaul Moore return ERR_CAST(filename); 358551689104SPaul Moore 35869883d185SAl Viro set_nameidata(&nd, -1, filename); 3587c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 358873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3589c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 359073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3591c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35929883d185SAl Viro restore_nameidata(); 359351689104SPaul Moore putname(filename); 359473d049a4SAl Viro return file; 359573d049a4SAl Viro } 359673d049a4SAl Viro 3597fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35981ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35991da177e4SLinus Torvalds { 3600c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3601391172c4SAl Viro struct qstr last; 3602391172c4SAl Viro int type; 3603c30dabfeSJan Kara int err2; 36041ac12b4bSJeff Layton int error; 36051ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 36061ac12b4bSJeff Layton 36071ac12b4bSJeff Layton /* 36081ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 36091ac12b4bSJeff Layton * other flags passed in are ignored! 36101ac12b4bSJeff Layton */ 36111ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 36121ac12b4bSJeff Layton 36135c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36145c31b6ceSAl Viro if (IS_ERR(name)) 36155c31b6ceSAl Viro return ERR_CAST(name); 36161da177e4SLinus Torvalds 3617c663e5d8SChristoph Hellwig /* 3618c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3619c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3620c663e5d8SChristoph Hellwig */ 36215c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3622ed75e95dSAl Viro goto out; 3623c663e5d8SChristoph Hellwig 3624c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3625391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3626c663e5d8SChristoph Hellwig /* 3627c663e5d8SChristoph Hellwig * Do the final lookup. 3628c663e5d8SChristoph Hellwig */ 3629391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36305955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3631391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36321da177e4SLinus Torvalds if (IS_ERR(dentry)) 3633a8104a9fSAl Viro goto unlock; 3634c663e5d8SChristoph Hellwig 3635a8104a9fSAl Viro error = -EEXIST; 3636b18825a7SDavid Howells if (d_is_positive(dentry)) 3637a8104a9fSAl Viro goto fail; 3638b18825a7SDavid Howells 3639c663e5d8SChristoph Hellwig /* 3640c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3641c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3642c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3643c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3644c663e5d8SChristoph Hellwig */ 3645391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3646a8104a9fSAl Viro error = -ENOENT; 3647ed75e95dSAl Viro goto fail; 3648e9baf6e5SAl Viro } 3649c30dabfeSJan Kara if (unlikely(err2)) { 3650c30dabfeSJan Kara error = err2; 3651a8104a9fSAl Viro goto fail; 3652c30dabfeSJan Kara } 3653181c37b6SAl Viro putname(name); 3654e9baf6e5SAl Viro return dentry; 36551da177e4SLinus Torvalds fail: 3656a8104a9fSAl Viro dput(dentry); 3657a8104a9fSAl Viro dentry = ERR_PTR(error); 3658a8104a9fSAl Viro unlock: 36595955102cSAl Viro inode_unlock(path->dentry->d_inode); 3660c30dabfeSJan Kara if (!err2) 3661391172c4SAl Viro mnt_drop_write(path->mnt); 3662ed75e95dSAl Viro out: 3663391172c4SAl Viro path_put(path); 3664181c37b6SAl Viro putname(name); 3665ed75e95dSAl Viro return dentry; 3666dae6ad8fSAl Viro } 3667fa14a0b8SAl Viro 3668fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3669fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3670fa14a0b8SAl Viro { 3671181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3672181c37b6SAl Viro path, lookup_flags); 3673fa14a0b8SAl Viro } 3674dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3675dae6ad8fSAl Viro 3676921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3677921a1650SAl Viro { 3678921a1650SAl Viro dput(dentry); 36795955102cSAl Viro inode_unlock(path->dentry->d_inode); 3680a8104a9fSAl Viro mnt_drop_write(path->mnt); 3681921a1650SAl Viro path_put(path); 3682921a1650SAl Viro } 3683921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3684921a1650SAl Viro 3685520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36861ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3687dae6ad8fSAl Viro { 3688181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3689dae6ad8fSAl Viro } 3690dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3691dae6ad8fSAl Viro 36921a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36931da177e4SLinus Torvalds { 3694a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36951da177e4SLinus Torvalds 36961da177e4SLinus Torvalds if (error) 36971da177e4SLinus Torvalds return error; 36981da177e4SLinus Torvalds 369994f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 37001da177e4SLinus Torvalds return -EPERM; 37011da177e4SLinus Torvalds 3702acfa4380SAl Viro if (!dir->i_op->mknod) 37031da177e4SLinus Torvalds return -EPERM; 37041da177e4SLinus Torvalds 370508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 370608ce5f16SSerge E. Hallyn if (error) 370708ce5f16SSerge E. Hallyn return error; 370808ce5f16SSerge E. Hallyn 37091da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 37101da177e4SLinus Torvalds if (error) 37111da177e4SLinus Torvalds return error; 37121da177e4SLinus Torvalds 37131da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3714a74574aaSStephen Smalley if (!error) 3715f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37161da177e4SLinus Torvalds return error; 37171da177e4SLinus Torvalds } 37184d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37191da177e4SLinus Torvalds 3720f69aac00SAl Viro static int may_mknod(umode_t mode) 3721463c3197SDave Hansen { 3722463c3197SDave Hansen switch (mode & S_IFMT) { 3723463c3197SDave Hansen case S_IFREG: 3724463c3197SDave Hansen case S_IFCHR: 3725463c3197SDave Hansen case S_IFBLK: 3726463c3197SDave Hansen case S_IFIFO: 3727463c3197SDave Hansen case S_IFSOCK: 3728463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3729463c3197SDave Hansen return 0; 3730463c3197SDave Hansen case S_IFDIR: 3731463c3197SDave Hansen return -EPERM; 3732463c3197SDave Hansen default: 3733463c3197SDave Hansen return -EINVAL; 3734463c3197SDave Hansen } 3735463c3197SDave Hansen } 3736463c3197SDave Hansen 373787c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 373887c4e192SDominik Brodowski unsigned int dev) 37391da177e4SLinus Torvalds { 37401da177e4SLinus Torvalds struct dentry *dentry; 3741dae6ad8fSAl Viro struct path path; 3742dae6ad8fSAl Viro int error; 3743972567f1SJeff Layton unsigned int lookup_flags = 0; 37441da177e4SLinus Torvalds 37458e4bfca1SAl Viro error = may_mknod(mode); 37468e4bfca1SAl Viro if (error) 37478e4bfca1SAl Viro return error; 3748972567f1SJeff Layton retry: 3749972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3750dae6ad8fSAl Viro if (IS_ERR(dentry)) 3751dae6ad8fSAl Viro return PTR_ERR(dentry); 37522ad94ae6SAl Viro 3753dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3754ce3b0f8dSAl Viro mode &= ~current_umask(); 3755dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3756be6d3e56SKentaro Takeda if (error) 3757a8104a9fSAl Viro goto out; 37581da177e4SLinus Torvalds switch (mode & S_IFMT) { 37591da177e4SLinus Torvalds case 0: case S_IFREG: 3760312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 376105d1a717SMimi Zohar if (!error) 376205d1a717SMimi Zohar ima_post_path_mknod(dentry); 37631da177e4SLinus Torvalds break; 37641da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3765dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37661da177e4SLinus Torvalds new_decode_dev(dev)); 37671da177e4SLinus Torvalds break; 37681da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3769dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37701da177e4SLinus Torvalds break; 37711da177e4SLinus Torvalds } 3772a8104a9fSAl Viro out: 3773921a1650SAl Viro done_path_create(&path, dentry); 3774972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3775972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3776972567f1SJeff Layton goto retry; 3777972567f1SJeff Layton } 37781da177e4SLinus Torvalds return error; 37791da177e4SLinus Torvalds } 37801da177e4SLinus Torvalds 378187c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 378287c4e192SDominik Brodowski unsigned int, dev) 378387c4e192SDominik Brodowski { 378487c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 378587c4e192SDominik Brodowski } 378687c4e192SDominik Brodowski 37878208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37885590ff0dSUlrich Drepper { 378987c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 37905590ff0dSUlrich Drepper } 37915590ff0dSUlrich Drepper 379218bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37931da177e4SLinus Torvalds { 3794a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37958de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37961da177e4SLinus Torvalds 37971da177e4SLinus Torvalds if (error) 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds 3800acfa4380SAl Viro if (!dir->i_op->mkdir) 38011da177e4SLinus Torvalds return -EPERM; 38021da177e4SLinus Torvalds 38031da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 38041da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 38051da177e4SLinus Torvalds if (error) 38061da177e4SLinus Torvalds return error; 38071da177e4SLinus Torvalds 38088de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 38098de52778SAl Viro return -EMLINK; 38108de52778SAl Viro 38111da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3812a74574aaSStephen Smalley if (!error) 3813f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 38141da177e4SLinus Torvalds return error; 38151da177e4SLinus Torvalds } 38164d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 38171da177e4SLinus Torvalds 38180101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 38191da177e4SLinus Torvalds { 38206902d925SDave Hansen struct dentry *dentry; 3821dae6ad8fSAl Viro struct path path; 3822dae6ad8fSAl Viro int error; 3823b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38241da177e4SLinus Torvalds 3825b76d8b82SJeff Layton retry: 3826b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38276902d925SDave Hansen if (IS_ERR(dentry)) 3828dae6ad8fSAl Viro return PTR_ERR(dentry); 38296902d925SDave Hansen 3830dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3831ce3b0f8dSAl Viro mode &= ~current_umask(); 3832dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3833a8104a9fSAl Viro if (!error) 3834dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3835921a1650SAl Viro done_path_create(&path, dentry); 3836b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3837b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3838b76d8b82SJeff Layton goto retry; 3839b76d8b82SJeff Layton } 38401da177e4SLinus Torvalds return error; 38411da177e4SLinus Torvalds } 38421da177e4SLinus Torvalds 38430101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38440101db7aSDominik Brodowski { 38450101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 38460101db7aSDominik Brodowski } 38470101db7aSDominik Brodowski 3848a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38495590ff0dSUlrich Drepper { 38500101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 38515590ff0dSUlrich Drepper } 38525590ff0dSUlrich Drepper 38531da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38541da177e4SLinus Torvalds { 38551da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38561da177e4SLinus Torvalds 38571da177e4SLinus Torvalds if (error) 38581da177e4SLinus Torvalds return error; 38591da177e4SLinus Torvalds 3860acfa4380SAl Viro if (!dir->i_op->rmdir) 38611da177e4SLinus Torvalds return -EPERM; 38621da177e4SLinus Torvalds 38631d2ef590SAl Viro dget(dentry); 38645955102cSAl Viro inode_lock(dentry->d_inode); 3865912dbc15SSage Weil 38661da177e4SLinus Torvalds error = -EBUSY; 38677af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3868912dbc15SSage Weil goto out; 3869912dbc15SSage Weil 38701da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3871912dbc15SSage Weil if (error) 3872912dbc15SSage Weil goto out; 3873912dbc15SSage Weil 38741da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3875912dbc15SSage Weil if (error) 3876912dbc15SSage Weil goto out; 3877912dbc15SSage Weil 38788767712fSAl Viro shrink_dcache_parent(dentry); 38791da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3880d83c49f3SAl Viro dont_mount(dentry); 38818ed936b5SEric W. Biederman detach_mounts(dentry); 3882116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 38831da177e4SLinus Torvalds 3884912dbc15SSage Weil out: 38855955102cSAl Viro inode_unlock(dentry->d_inode); 38861d2ef590SAl Viro dput(dentry); 3887912dbc15SSage Weil if (!error) 3888912dbc15SSage Weil d_delete(dentry); 38891da177e4SLinus Torvalds return error; 38901da177e4SLinus Torvalds } 38914d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38921da177e4SLinus Torvalds 3893f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 38941da177e4SLinus Torvalds { 38951da177e4SLinus Torvalds int error = 0; 389691a27b2aSJeff Layton struct filename *name; 38971da177e4SLinus Torvalds struct dentry *dentry; 3898f5beed75SAl Viro struct path path; 3899f5beed75SAl Viro struct qstr last; 3900f5beed75SAl Viro int type; 3901c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3902c6ee9206SJeff Layton retry: 3903c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3904c1d4dd27SAl Viro &path, &last, &type); 390591a27b2aSJeff Layton if (IS_ERR(name)) 390691a27b2aSJeff Layton return PTR_ERR(name); 39071da177e4SLinus Torvalds 3908f5beed75SAl Viro switch (type) { 39091da177e4SLinus Torvalds case LAST_DOTDOT: 39101da177e4SLinus Torvalds error = -ENOTEMPTY; 39111da177e4SLinus Torvalds goto exit1; 39121da177e4SLinus Torvalds case LAST_DOT: 39131da177e4SLinus Torvalds error = -EINVAL; 39141da177e4SLinus Torvalds goto exit1; 39151da177e4SLinus Torvalds case LAST_ROOT: 39161da177e4SLinus Torvalds error = -EBUSY; 39171da177e4SLinus Torvalds goto exit1; 39181da177e4SLinus Torvalds } 39190612d9fbSOGAWA Hirofumi 3920f5beed75SAl Viro error = mnt_want_write(path.mnt); 3921c30dabfeSJan Kara if (error) 3922c30dabfeSJan Kara goto exit1; 39230612d9fbSOGAWA Hirofumi 39245955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3925f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39261da177e4SLinus Torvalds error = PTR_ERR(dentry); 39276902d925SDave Hansen if (IS_ERR(dentry)) 39286902d925SDave Hansen goto exit2; 3929e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3930e6bc45d6STheodore Ts'o error = -ENOENT; 3931e6bc45d6STheodore Ts'o goto exit3; 3932e6bc45d6STheodore Ts'o } 3933f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3934be6d3e56SKentaro Takeda if (error) 3935c30dabfeSJan Kara goto exit3; 3936f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39370622753bSDave Hansen exit3: 39381da177e4SLinus Torvalds dput(dentry); 39396902d925SDave Hansen exit2: 39405955102cSAl Viro inode_unlock(path.dentry->d_inode); 3941f5beed75SAl Viro mnt_drop_write(path.mnt); 39421da177e4SLinus Torvalds exit1: 3943f5beed75SAl Viro path_put(&path); 39441da177e4SLinus Torvalds putname(name); 3945c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3946c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3947c6ee9206SJeff Layton goto retry; 3948c6ee9206SJeff Layton } 39491da177e4SLinus Torvalds return error; 39501da177e4SLinus Torvalds } 39511da177e4SLinus Torvalds 39523cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39535590ff0dSUlrich Drepper { 39545590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39555590ff0dSUlrich Drepper } 39565590ff0dSUlrich Drepper 3957b21996e3SJ. Bruce Fields /** 3958b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3959b21996e3SJ. Bruce Fields * @dir: parent directory 3960b21996e3SJ. Bruce Fields * @dentry: victim 3961b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3962b21996e3SJ. Bruce Fields * 3963b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3964b21996e3SJ. Bruce Fields * 3965b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3966b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3967b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3968b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3969b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3970b21996e3SJ. Bruce Fields * 3971b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3972b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3973b21996e3SJ. Bruce Fields * to be NFS exported. 3974b21996e3SJ. Bruce Fields */ 3975b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39761da177e4SLinus Torvalds { 39779accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39781da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39791da177e4SLinus Torvalds 39801da177e4SLinus Torvalds if (error) 39811da177e4SLinus Torvalds return error; 39821da177e4SLinus Torvalds 3983acfa4380SAl Viro if (!dir->i_op->unlink) 39841da177e4SLinus Torvalds return -EPERM; 39851da177e4SLinus Torvalds 39865955102cSAl Viro inode_lock(target); 39878ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39881da177e4SLinus Torvalds error = -EBUSY; 39891da177e4SLinus Torvalds else { 39901da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3991bec1052eSAl Viro if (!error) { 39925a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39935a14696cSJ. Bruce Fields if (error) 3994b21996e3SJ. Bruce Fields goto out; 39951da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39968ed936b5SEric W. Biederman if (!error) { 3997d83c49f3SAl Viro dont_mount(dentry); 39988ed936b5SEric W. Biederman detach_mounts(dentry); 3999116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 40008ed936b5SEric W. Biederman } 4001bec1052eSAl Viro } 40021da177e4SLinus Torvalds } 4003b21996e3SJ. Bruce Fields out: 40045955102cSAl Viro inode_unlock(target); 40051da177e4SLinus Torvalds 40061da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 40071da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 40089accbb97SJ. Bruce Fields fsnotify_link_count(target); 40091da177e4SLinus Torvalds d_delete(dentry); 40101da177e4SLinus Torvalds } 40110eeca283SRobert Love 40121da177e4SLinus Torvalds return error; 40131da177e4SLinus Torvalds } 40144d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 40151da177e4SLinus Torvalds 40161da177e4SLinus Torvalds /* 40171da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 40181b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 40191da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 40201da177e4SLinus Torvalds * while waiting on the I/O. 40211da177e4SLinus Torvalds */ 4022da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 40231da177e4SLinus Torvalds { 40242ad94ae6SAl Viro int error; 40251da177e4SLinus Torvalds struct dentry *dentry; 4026f5beed75SAl Viro struct path path; 4027f5beed75SAl Viro struct qstr last; 4028f5beed75SAl Viro int type; 40291da177e4SLinus Torvalds struct inode *inode = NULL; 4030b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40315d18f813SJeff Layton unsigned int lookup_flags = 0; 40325d18f813SJeff Layton retry: 4033da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 403491a27b2aSJeff Layton if (IS_ERR(name)) 403591a27b2aSJeff Layton return PTR_ERR(name); 40362ad94ae6SAl Viro 40371da177e4SLinus Torvalds error = -EISDIR; 4038f5beed75SAl Viro if (type != LAST_NORM) 40391da177e4SLinus Torvalds goto exit1; 40400612d9fbSOGAWA Hirofumi 4041f5beed75SAl Viro error = mnt_want_write(path.mnt); 4042c30dabfeSJan Kara if (error) 4043c30dabfeSJan Kara goto exit1; 4044b21996e3SJ. Bruce Fields retry_deleg: 40455955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4046f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40471da177e4SLinus Torvalds error = PTR_ERR(dentry); 40481da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40491da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4050f5beed75SAl Viro if (last.name[last.len]) 405150338b88STörök Edwin goto slashes; 40521da177e4SLinus Torvalds inode = dentry->d_inode; 4053b18825a7SDavid Howells if (d_is_negative(dentry)) 4054e6bc45d6STheodore Ts'o goto slashes; 40557de9c6eeSAl Viro ihold(inode); 4056f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4057be6d3e56SKentaro Takeda if (error) 4058c30dabfeSJan Kara goto exit2; 4059f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40601da177e4SLinus Torvalds exit2: 40611da177e4SLinus Torvalds dput(dentry); 40621da177e4SLinus Torvalds } 40635955102cSAl Viro inode_unlock(path.dentry->d_inode); 40641da177e4SLinus Torvalds if (inode) 40651da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4066b21996e3SJ. Bruce Fields inode = NULL; 4067b21996e3SJ. Bruce Fields if (delegated_inode) { 40685a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4069b21996e3SJ. Bruce Fields if (!error) 4070b21996e3SJ. Bruce Fields goto retry_deleg; 4071b21996e3SJ. Bruce Fields } 4072f5beed75SAl Viro mnt_drop_write(path.mnt); 40731da177e4SLinus Torvalds exit1: 4074f5beed75SAl Viro path_put(&path); 40755d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40765d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40775d18f813SJeff Layton inode = NULL; 40785d18f813SJeff Layton goto retry; 40795d18f813SJeff Layton } 4080da2f1362SChristoph Hellwig putname(name); 40811da177e4SLinus Torvalds return error; 40821da177e4SLinus Torvalds 40831da177e4SLinus Torvalds slashes: 4084b18825a7SDavid Howells if (d_is_negative(dentry)) 4085b18825a7SDavid Howells error = -ENOENT; 408644b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4087b18825a7SDavid Howells error = -EISDIR; 4088b18825a7SDavid Howells else 4089b18825a7SDavid Howells error = -ENOTDIR; 40901da177e4SLinus Torvalds goto exit2; 40911da177e4SLinus Torvalds } 40921da177e4SLinus Torvalds 40932e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40945590ff0dSUlrich Drepper { 40955590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40965590ff0dSUlrich Drepper return -EINVAL; 40975590ff0dSUlrich Drepper 40985590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40995590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 41005590ff0dSUlrich Drepper 4101da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 41025590ff0dSUlrich Drepper } 41035590ff0dSUlrich Drepper 41043480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 41055590ff0dSUlrich Drepper { 4106da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 41075590ff0dSUlrich Drepper } 41085590ff0dSUlrich Drepper 4109db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 41101da177e4SLinus Torvalds { 4111a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 41121da177e4SLinus Torvalds 41131da177e4SLinus Torvalds if (error) 41141da177e4SLinus Torvalds return error; 41151da177e4SLinus Torvalds 4116acfa4380SAl Viro if (!dir->i_op->symlink) 41171da177e4SLinus Torvalds return -EPERM; 41181da177e4SLinus Torvalds 41191da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 41201da177e4SLinus Torvalds if (error) 41211da177e4SLinus Torvalds return error; 41221da177e4SLinus Torvalds 41231da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4124a74574aaSStephen Smalley if (!error) 4125f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41261da177e4SLinus Torvalds return error; 41271da177e4SLinus Torvalds } 41284d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41291da177e4SLinus Torvalds 4130b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4131b724e846SDominik Brodowski const char __user *newname) 41321da177e4SLinus Torvalds { 41332ad94ae6SAl Viro int error; 413491a27b2aSJeff Layton struct filename *from; 41356902d925SDave Hansen struct dentry *dentry; 4136dae6ad8fSAl Viro struct path path; 4137f46d3567SJeff Layton unsigned int lookup_flags = 0; 41381da177e4SLinus Torvalds 41391da177e4SLinus Torvalds from = getname(oldname); 41401da177e4SLinus Torvalds if (IS_ERR(from)) 41411da177e4SLinus Torvalds return PTR_ERR(from); 4142f46d3567SJeff Layton retry: 4143f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41441da177e4SLinus Torvalds error = PTR_ERR(dentry); 41456902d925SDave Hansen if (IS_ERR(dentry)) 4146dae6ad8fSAl Viro goto out_putname; 41476902d925SDave Hansen 414891a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4149a8104a9fSAl Viro if (!error) 415091a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4151921a1650SAl Viro done_path_create(&path, dentry); 4152f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4153f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4154f46d3567SJeff Layton goto retry; 4155f46d3567SJeff Layton } 41566902d925SDave Hansen out_putname: 41571da177e4SLinus Torvalds putname(from); 41581da177e4SLinus Torvalds return error; 41591da177e4SLinus Torvalds } 41601da177e4SLinus Torvalds 4161b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4162b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4163b724e846SDominik Brodowski { 4164b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4165b724e846SDominik Brodowski } 4166b724e846SDominik Brodowski 41673480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41685590ff0dSUlrich Drepper { 4169b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 41705590ff0dSUlrich Drepper } 41715590ff0dSUlrich Drepper 4172146a8595SJ. Bruce Fields /** 4173146a8595SJ. Bruce Fields * vfs_link - create a new link 4174146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4175146a8595SJ. Bruce Fields * @dir: new parent 4176146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4177146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4178146a8595SJ. Bruce Fields * 4179146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4180146a8595SJ. Bruce Fields * 4181146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4182146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4183146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4184146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4185146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4186146a8595SJ. Bruce Fields * 4187146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4188146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4189146a8595SJ. Bruce Fields * to be NFS exported. 4190146a8595SJ. Bruce Fields */ 4191146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41921da177e4SLinus Torvalds { 41931da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41948de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41951da177e4SLinus Torvalds int error; 41961da177e4SLinus Torvalds 41971da177e4SLinus Torvalds if (!inode) 41981da177e4SLinus Torvalds return -ENOENT; 41991da177e4SLinus Torvalds 4200a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 42011da177e4SLinus Torvalds if (error) 42021da177e4SLinus Torvalds return error; 42031da177e4SLinus Torvalds 42041da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 42051da177e4SLinus Torvalds return -EXDEV; 42061da177e4SLinus Torvalds 42071da177e4SLinus Torvalds /* 42081da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 42091da177e4SLinus Torvalds */ 42101da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 42111da177e4SLinus Torvalds return -EPERM; 42120bd23d09SEric W. Biederman /* 42130bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 42140bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 42150bd23d09SEric W. Biederman * the vfs. 42160bd23d09SEric W. Biederman */ 42170bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 42180bd23d09SEric W. Biederman return -EPERM; 4219acfa4380SAl Viro if (!dir->i_op->link) 42201da177e4SLinus Torvalds return -EPERM; 42217e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 42221da177e4SLinus Torvalds return -EPERM; 42231da177e4SLinus Torvalds 42241da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 42251da177e4SLinus Torvalds if (error) 42261da177e4SLinus Torvalds return error; 42271da177e4SLinus Torvalds 42285955102cSAl Viro inode_lock(inode); 4229aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4230f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4231aae8a97dSAneesh Kumar K.V error = -ENOENT; 42328de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 42338de52778SAl Viro error = -EMLINK; 4234146a8595SJ. Bruce Fields else { 4235146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4236146a8595SJ. Bruce Fields if (!error) 42371da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4238146a8595SJ. Bruce Fields } 4239f4e0c30cSAl Viro 4240f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4241f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4242f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4243f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4244f4e0c30cSAl Viro } 42455955102cSAl Viro inode_unlock(inode); 4246e31e14ecSStephen Smalley if (!error) 42477e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42481da177e4SLinus Torvalds return error; 42491da177e4SLinus Torvalds } 42504d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42511da177e4SLinus Torvalds 42521da177e4SLinus Torvalds /* 42531da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42541da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42551da177e4SLinus Torvalds * newname. --KAB 42561da177e4SLinus Torvalds * 42571da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42581da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42591da177e4SLinus Torvalds * and other special files. --ADM 42601da177e4SLinus Torvalds */ 426146ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 426246ea89ebSDominik Brodowski const char __user *newname, int flags) 42631da177e4SLinus Torvalds { 42641da177e4SLinus Torvalds struct dentry *new_dentry; 4265dae6ad8fSAl Viro struct path old_path, new_path; 4266146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 426711a7b371SAneesh Kumar K.V int how = 0; 42681da177e4SLinus Torvalds int error; 42691da177e4SLinus Torvalds 427011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4271c04030e1SUlrich Drepper return -EINVAL; 427211a7b371SAneesh Kumar K.V /* 4273f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4274f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4275f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 427611a7b371SAneesh Kumar K.V */ 4277f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4278f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4279f0cc6ffbSLinus Torvalds return -ENOENT; 428011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4281f0cc6ffbSLinus Torvalds } 4282c04030e1SUlrich Drepper 428311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 428411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4285442e31caSJeff Layton retry: 428611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42871da177e4SLinus Torvalds if (error) 42882ad94ae6SAl Viro return error; 42892ad94ae6SAl Viro 4290442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4291442e31caSJeff Layton (how & LOOKUP_REVAL)); 42921da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42936902d925SDave Hansen if (IS_ERR(new_dentry)) 4294dae6ad8fSAl Viro goto out; 4295dae6ad8fSAl Viro 4296dae6ad8fSAl Viro error = -EXDEV; 4297dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4298dae6ad8fSAl Viro goto out_dput; 4299800179c9SKees Cook error = may_linkat(&old_path); 4300800179c9SKees Cook if (unlikely(error)) 4301800179c9SKees Cook goto out_dput; 4302dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4303be6d3e56SKentaro Takeda if (error) 4304a8104a9fSAl Viro goto out_dput; 4305146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 430675c3f29dSDave Hansen out_dput: 4307921a1650SAl Viro done_path_create(&new_path, new_dentry); 4308146a8595SJ. Bruce Fields if (delegated_inode) { 4309146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4310d22e6338SOleg Drokin if (!error) { 4311d22e6338SOleg Drokin path_put(&old_path); 4312146a8595SJ. Bruce Fields goto retry; 4313146a8595SJ. Bruce Fields } 4314d22e6338SOleg Drokin } 4315442e31caSJeff Layton if (retry_estale(error, how)) { 4316d22e6338SOleg Drokin path_put(&old_path); 4317442e31caSJeff Layton how |= LOOKUP_REVAL; 4318442e31caSJeff Layton goto retry; 4319442e31caSJeff Layton } 43201da177e4SLinus Torvalds out: 43212d8f3038SAl Viro path_put(&old_path); 43221da177e4SLinus Torvalds 43231da177e4SLinus Torvalds return error; 43241da177e4SLinus Torvalds } 43251da177e4SLinus Torvalds 432646ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 432746ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 432846ea89ebSDominik Brodowski { 432946ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 433046ea89ebSDominik Brodowski } 433146ea89ebSDominik Brodowski 43323480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 43335590ff0dSUlrich Drepper { 433446ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43355590ff0dSUlrich Drepper } 43365590ff0dSUlrich Drepper 4337bc27027aSMiklos Szeredi /** 4338bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4339bc27027aSMiklos Szeredi * @old_dir: parent of source 4340bc27027aSMiklos Szeredi * @old_dentry: source 4341bc27027aSMiklos Szeredi * @new_dir: parent of destination 4342bc27027aSMiklos Szeredi * @new_dentry: destination 4343bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4344520c8b16SMiklos Szeredi * @flags: rename flags 4345bc27027aSMiklos Szeredi * 4346bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4347bc27027aSMiklos Szeredi * 4348bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4349bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4350bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4351bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4352bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4353bc27027aSMiklos Szeredi * so. 4354bc27027aSMiklos Szeredi * 4355bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4356bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4357bc27027aSMiklos Szeredi * to be NFS exported. 4358bc27027aSMiklos Szeredi * 43591da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43601da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43611da177e4SLinus Torvalds * Problems: 43620117d427SMauro Carvalho Chehab * 4363d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43641da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43651da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4366a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43671da177e4SLinus Torvalds * story. 43686cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43696cedba89SJ. Bruce Fields * and source (if it is not a directory). 43701b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43711da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43721da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4373a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43741da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43751da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43761da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4377a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43781da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43791da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43801da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4381e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43821b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43831da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4384c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43851da177e4SLinus Torvalds * locking]. 43861da177e4SLinus Torvalds */ 43871da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43888e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4389520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43901da177e4SLinus Torvalds { 43911da177e4SLinus Torvalds int error; 4392bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4393bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4394bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4395da1ce067SMiklos Szeredi bool new_is_dir = false; 4396da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 439749d31c2fSAl Viro struct name_snapshot old_name; 43981da177e4SLinus Torvalds 43998d3e2936SMiklos Szeredi if (source == target) 44001da177e4SLinus Torvalds return 0; 44011da177e4SLinus Torvalds 44021da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 44031da177e4SLinus Torvalds if (error) 44041da177e4SLinus Torvalds return error; 44051da177e4SLinus Torvalds 4406da1ce067SMiklos Szeredi if (!target) { 4407a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4408da1ce067SMiklos Szeredi } else { 4409da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4410da1ce067SMiklos Szeredi 4411da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44121da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4413da1ce067SMiklos Szeredi else 4414da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4415da1ce067SMiklos Szeredi } 44161da177e4SLinus Torvalds if (error) 44171da177e4SLinus Torvalds return error; 44181da177e4SLinus Torvalds 44192773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 44201da177e4SLinus Torvalds return -EPERM; 44211da177e4SLinus Torvalds 4422bc27027aSMiklos Szeredi /* 4423bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4424bc27027aSMiklos Szeredi * we'll need to flip '..'. 4425bc27027aSMiklos Szeredi */ 4426da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4427da1ce067SMiklos Szeredi if (is_dir) { 4428bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4429bc27027aSMiklos Szeredi if (error) 4430bc27027aSMiklos Szeredi return error; 4431bc27027aSMiklos Szeredi } 4432da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4433da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4434da1ce067SMiklos Szeredi if (error) 4435da1ce067SMiklos Szeredi return error; 4436da1ce067SMiklos Szeredi } 4437da1ce067SMiklos Szeredi } 44380eeca283SRobert Love 44390b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44400b3974ebSMiklos Szeredi flags); 4441bc27027aSMiklos Szeredi if (error) 4442bc27027aSMiklos Szeredi return error; 4443bc27027aSMiklos Szeredi 444449d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4445bc27027aSMiklos Szeredi dget(new_dentry); 4446da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4447bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4448bc27027aSMiklos Szeredi else if (target) 44495955102cSAl Viro inode_lock(target); 4450bc27027aSMiklos Szeredi 4451bc27027aSMiklos Szeredi error = -EBUSY; 44527af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4453bc27027aSMiklos Szeredi goto out; 4454bc27027aSMiklos Szeredi 4455da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4456bc27027aSMiklos Szeredi error = -EMLINK; 4457da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4458bc27027aSMiklos Szeredi goto out; 4459da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4460da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4461da1ce067SMiklos Szeredi goto out; 4462da1ce067SMiklos Szeredi } 4463da1ce067SMiklos Szeredi if (!is_dir) { 4464bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4465bc27027aSMiklos Szeredi if (error) 4466bc27027aSMiklos Szeredi goto out; 4467da1ce067SMiklos Szeredi } 4468da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4469bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4470bc27027aSMiklos Szeredi if (error) 4471bc27027aSMiklos Szeredi goto out; 4472bc27027aSMiklos Szeredi } 4473520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4474520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4475bc27027aSMiklos Szeredi if (error) 4476bc27027aSMiklos Szeredi goto out; 4477bc27027aSMiklos Szeredi 4478da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44798767712fSAl Viro if (is_dir) { 44808767712fSAl Viro shrink_dcache_parent(new_dentry); 4481bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 44828767712fSAl Viro } 4483bc27027aSMiklos Szeredi dont_mount(new_dentry); 44848ed936b5SEric W. Biederman detach_mounts(new_dentry); 4485bc27027aSMiklos Szeredi } 4486da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4487da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4488bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4489da1ce067SMiklos Szeredi else 4490da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4491da1ce067SMiklos Szeredi } 4492bc27027aSMiklos Szeredi out: 4493da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4494bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4495bc27027aSMiklos Szeredi else if (target) 44965955102cSAl Viro inode_unlock(target); 4497bc27027aSMiklos Szeredi dput(new_dentry); 4498da1ce067SMiklos Szeredi if (!error) { 4499f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4500da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4501da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4502f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4503da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4504da1ce067SMiklos Szeredi } 4505da1ce067SMiklos Szeredi } 450649d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 45070eeca283SRobert Love 45081da177e4SLinus Torvalds return error; 45091da177e4SLinus Torvalds } 45104d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 45111da177e4SLinus Torvalds 4512ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4513ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 45141da177e4SLinus Torvalds { 45151da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 45161da177e4SLinus Torvalds struct dentry *trap; 4517f5beed75SAl Viro struct path old_path, new_path; 4518f5beed75SAl Viro struct qstr old_last, new_last; 4519f5beed75SAl Viro int old_type, new_type; 45208e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 452191a27b2aSJeff Layton struct filename *from; 452291a27b2aSJeff Layton struct filename *to; 4523f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4524c6a94284SJeff Layton bool should_retry = false; 45252ad94ae6SAl Viro int error; 4526520c8b16SMiklos Szeredi 45270d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4528da1ce067SMiklos Szeredi return -EINVAL; 4529da1ce067SMiklos Szeredi 45300d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 45310d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4532520c8b16SMiklos Szeredi return -EINVAL; 4533520c8b16SMiklos Szeredi 45340d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 45350d7a8555SMiklos Szeredi return -EPERM; 45360d7a8555SMiklos Szeredi 4537f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4538f5beed75SAl Viro target_flags = 0; 4539f5beed75SAl Viro 4540c6a94284SJeff Layton retry: 4541c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4542c1d4dd27SAl Viro &old_path, &old_last, &old_type); 454391a27b2aSJeff Layton if (IS_ERR(from)) { 454491a27b2aSJeff Layton error = PTR_ERR(from); 45451da177e4SLinus Torvalds goto exit; 454691a27b2aSJeff Layton } 45471da177e4SLinus Torvalds 4548c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4549c1d4dd27SAl Viro &new_path, &new_last, &new_type); 455091a27b2aSJeff Layton if (IS_ERR(to)) { 455191a27b2aSJeff Layton error = PTR_ERR(to); 45521da177e4SLinus Torvalds goto exit1; 455391a27b2aSJeff Layton } 45541da177e4SLinus Torvalds 45551da177e4SLinus Torvalds error = -EXDEV; 4556f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45571da177e4SLinus Torvalds goto exit2; 45581da177e4SLinus Torvalds 45591da177e4SLinus Torvalds error = -EBUSY; 4560f5beed75SAl Viro if (old_type != LAST_NORM) 45611da177e4SLinus Torvalds goto exit2; 45621da177e4SLinus Torvalds 45630a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45640a7c3937SMiklos Szeredi error = -EEXIST; 4565f5beed75SAl Viro if (new_type != LAST_NORM) 45661da177e4SLinus Torvalds goto exit2; 45671da177e4SLinus Torvalds 4568f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4569c30dabfeSJan Kara if (error) 4570c30dabfeSJan Kara goto exit2; 4571c30dabfeSJan Kara 45728e6d782cSJ. Bruce Fields retry_deleg: 4573f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45741da177e4SLinus Torvalds 4575f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45761da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45771da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45781da177e4SLinus Torvalds goto exit3; 45791da177e4SLinus Torvalds /* source must exist */ 45801da177e4SLinus Torvalds error = -ENOENT; 4581b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45821da177e4SLinus Torvalds goto exit4; 4583f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45841da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45851da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45861da177e4SLinus Torvalds goto exit4; 45870a7c3937SMiklos Szeredi error = -EEXIST; 45880a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45890a7c3937SMiklos Szeredi goto exit5; 4590da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4591da1ce067SMiklos Szeredi error = -ENOENT; 4592da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4593da1ce067SMiklos Szeredi goto exit5; 4594da1ce067SMiklos Szeredi 4595da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4596da1ce067SMiklos Szeredi error = -ENOTDIR; 4597f5beed75SAl Viro if (new_last.name[new_last.len]) 4598da1ce067SMiklos Szeredi goto exit5; 4599da1ce067SMiklos Szeredi } 4600da1ce067SMiklos Szeredi } 46010a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 46020a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 46030a7c3937SMiklos Szeredi error = -ENOTDIR; 4604f5beed75SAl Viro if (old_last.name[old_last.len]) 46050a7c3937SMiklos Szeredi goto exit5; 4606f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 46070a7c3937SMiklos Szeredi goto exit5; 46080a7c3937SMiklos Szeredi } 46090a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 46100a7c3937SMiklos Szeredi error = -EINVAL; 46110a7c3937SMiklos Szeredi if (old_dentry == trap) 46120a7c3937SMiklos Szeredi goto exit5; 46131da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4614da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 46151da177e4SLinus Torvalds error = -ENOTEMPTY; 46161da177e4SLinus Torvalds if (new_dentry == trap) 46171da177e4SLinus Torvalds goto exit5; 46181da177e4SLinus Torvalds 4619f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4620f5beed75SAl Viro &new_path, new_dentry, flags); 4621be6d3e56SKentaro Takeda if (error) 4622c30dabfeSJan Kara goto exit5; 4623f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4624f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4625520c8b16SMiklos Szeredi &delegated_inode, flags); 46261da177e4SLinus Torvalds exit5: 46271da177e4SLinus Torvalds dput(new_dentry); 46281da177e4SLinus Torvalds exit4: 46291da177e4SLinus Torvalds dput(old_dentry); 46301da177e4SLinus Torvalds exit3: 4631f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 46328e6d782cSJ. Bruce Fields if (delegated_inode) { 46338e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 46348e6d782cSJ. Bruce Fields if (!error) 46358e6d782cSJ. Bruce Fields goto retry_deleg; 46368e6d782cSJ. Bruce Fields } 4637f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46381da177e4SLinus Torvalds exit2: 4639c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4640c6a94284SJeff Layton should_retry = true; 4641f5beed75SAl Viro path_put(&new_path); 46422ad94ae6SAl Viro putname(to); 46431da177e4SLinus Torvalds exit1: 4644f5beed75SAl Viro path_put(&old_path); 46451da177e4SLinus Torvalds putname(from); 4646c6a94284SJeff Layton if (should_retry) { 4647c6a94284SJeff Layton should_retry = false; 4648c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4649c6a94284SJeff Layton goto retry; 4650c6a94284SJeff Layton } 46512ad94ae6SAl Viro exit: 46521da177e4SLinus Torvalds return error; 46531da177e4SLinus Torvalds } 46541da177e4SLinus Torvalds 4655ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4656ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4657ee81feb6SDominik Brodowski { 4658ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4659ee81feb6SDominik Brodowski } 4660ee81feb6SDominik Brodowski 4661520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4662520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4663520c8b16SMiklos Szeredi { 4664ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4665520c8b16SMiklos Szeredi } 4666520c8b16SMiklos Szeredi 4667a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46685590ff0dSUlrich Drepper { 4669ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46705590ff0dSUlrich Drepper } 46715590ff0dSUlrich Drepper 4672787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4673787fb6bcSMiklos Szeredi { 4674787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4675787fb6bcSMiklos Szeredi if (error) 4676787fb6bcSMiklos Szeredi return error; 4677787fb6bcSMiklos Szeredi 4678787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4679787fb6bcSMiklos Szeredi return -EPERM; 4680787fb6bcSMiklos Szeredi 4681787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4682787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4683787fb6bcSMiklos Szeredi } 4684787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4685787fb6bcSMiklos Szeredi 46865d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46871da177e4SLinus Torvalds { 46885d826c84SAl Viro int len = PTR_ERR(link); 46891da177e4SLinus Torvalds if (IS_ERR(link)) 46901da177e4SLinus Torvalds goto out; 46911da177e4SLinus Torvalds 46921da177e4SLinus Torvalds len = strlen(link); 46931da177e4SLinus Torvalds if (len > (unsigned) buflen) 46941da177e4SLinus Torvalds len = buflen; 46951da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46961da177e4SLinus Torvalds len = -EFAULT; 46971da177e4SLinus Torvalds out: 46981da177e4SLinus Torvalds return len; 46991da177e4SLinus Torvalds } 47001da177e4SLinus Torvalds 4701d60874cdSMiklos Szeredi /** 4702fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4703fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4704fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4705fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4706fd4a0edfSMiklos Szeredi * 4707fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4708fd4a0edfSMiklos Szeredi * 4709fd4a0edfSMiklos Szeredi * Does not call security hook. 4710fd4a0edfSMiklos Szeredi */ 4711fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4712fd4a0edfSMiklos Szeredi { 4713fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4714f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4715f2df5da6SAl Viro const char *link; 4716f2df5da6SAl Viro int res; 4717fd4a0edfSMiklos Szeredi 471876fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 471976fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 472076fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 472176fca90eSMiklos Szeredi 472276fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4723fd4a0edfSMiklos Szeredi return -EINVAL; 4724fd4a0edfSMiklos Szeredi 472576fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 472676fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 472776fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 472876fca90eSMiklos Szeredi } 472976fca90eSMiklos Szeredi 47304c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4731f2df5da6SAl Viro if (!link) { 4732f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4733f2df5da6SAl Viro if (IS_ERR(link)) 4734f2df5da6SAl Viro return PTR_ERR(link); 4735f2df5da6SAl Viro } 4736f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4737f2df5da6SAl Viro do_delayed_call(&done); 4738f2df5da6SAl Viro return res; 4739fd4a0edfSMiklos Szeredi } 4740fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 47411da177e4SLinus Torvalds 4742d60874cdSMiklos Szeredi /** 4743d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4744d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4745d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4746d60874cdSMiklos Szeredi * 4747d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4748d60874cdSMiklos Szeredi * 4749d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4750d60874cdSMiklos Szeredi * 4751d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4752d60874cdSMiklos Szeredi */ 4753d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4754d60874cdSMiklos Szeredi { 4755d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4756d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4757d60874cdSMiklos Szeredi 4758d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4759d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4760d60874cdSMiklos Szeredi if (!res) 4761d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4762d60874cdSMiklos Szeredi } 4763d60874cdSMiklos Szeredi return res; 4764d60874cdSMiklos Szeredi } 4765d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4766d60874cdSMiklos Szeredi 47671da177e4SLinus Torvalds /* get the link contents into pagecache */ 47686b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4769fceef393SAl Viro struct delayed_call *callback) 47701da177e4SLinus Torvalds { 4771ebd09abbSDuane Griffin char *kaddr; 47721da177e4SLinus Torvalds struct page *page; 47736b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47746b255391SAl Viro 4775d3883d4fSAl Viro if (!dentry) { 4776d3883d4fSAl Viro page = find_get_page(mapping, 0); 4777d3883d4fSAl Viro if (!page) 47786b255391SAl Viro return ERR_PTR(-ECHILD); 4779d3883d4fSAl Viro if (!PageUptodate(page)) { 4780d3883d4fSAl Viro put_page(page); 4781d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4782d3883d4fSAl Viro } 4783d3883d4fSAl Viro } else { 4784090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47851da177e4SLinus Torvalds if (IS_ERR(page)) 47866fe6900eSNick Piggin return (char*)page; 4787d3883d4fSAl Viro } 4788fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 478921fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 479021fc61c7SAl Viro kaddr = page_address(page); 47916b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4792ebd09abbSDuane Griffin return kaddr; 47931da177e4SLinus Torvalds } 47941da177e4SLinus Torvalds 47956b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47961da177e4SLinus Torvalds 4797fceef393SAl Viro void page_put_link(void *arg) 47981da177e4SLinus Torvalds { 4799fceef393SAl Viro put_page(arg); 48001da177e4SLinus Torvalds } 48014d359507SAl Viro EXPORT_SYMBOL(page_put_link); 48021da177e4SLinus Torvalds 4803aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4804aa80deabSAl Viro { 4805fceef393SAl Viro DEFINE_DELAYED_CALL(done); 48066b255391SAl Viro int res = readlink_copy(buffer, buflen, 48076b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4808fceef393SAl Viro &done)); 4809fceef393SAl Viro do_delayed_call(&done); 4810aa80deabSAl Viro return res; 4811aa80deabSAl Viro } 4812aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4813aa80deabSAl Viro 481454566b2cSNick Piggin /* 481554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 481654566b2cSNick Piggin */ 481754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 48181da177e4SLinus Torvalds { 48191da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 48200adb25d2SKirill Korotaev struct page *page; 4821afddba49SNick Piggin void *fsdata; 4822beb497abSDmitriy Monakhov int err; 4823c718a975STetsuo Handa unsigned int flags = 0; 482454566b2cSNick Piggin if (nofs) 482554566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 48261da177e4SLinus Torvalds 48277e53cac4SNeilBrown retry: 4828afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 482954566b2cSNick Piggin flags, &page, &fsdata); 48301da177e4SLinus Torvalds if (err) 4831afddba49SNick Piggin goto fail; 4832afddba49SNick Piggin 483321fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4834afddba49SNick Piggin 4835afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4836afddba49SNick Piggin page, fsdata); 48371da177e4SLinus Torvalds if (err < 0) 48381da177e4SLinus Torvalds goto fail; 4839afddba49SNick Piggin if (err < len-1) 4840afddba49SNick Piggin goto retry; 4841afddba49SNick Piggin 48421da177e4SLinus Torvalds mark_inode_dirty(inode); 48431da177e4SLinus Torvalds return 0; 48441da177e4SLinus Torvalds fail: 48451da177e4SLinus Torvalds return err; 48461da177e4SLinus Torvalds } 48474d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48481da177e4SLinus Torvalds 48490adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48500adb25d2SKirill Korotaev { 48510adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4852c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48530adb25d2SKirill Korotaev } 48544d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48550adb25d2SKirill Korotaev 485692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48576b255391SAl Viro .get_link = page_get_link, 48581da177e4SLinus Torvalds }; 48591da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4860