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); 92894b9d9b7SRichard Guy Briggs audit_log_link_denied("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 99694b9d9b7SRichard Guy Briggs audit_log_link_denied("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))))) { 103430aba665SSalvatore Mesoraca return -EACCES; 103530aba665SSalvatore Mesoraca } 103630aba665SSalvatore Mesoraca return 0; 103730aba665SSalvatore Mesoraca } 103830aba665SSalvatore Mesoraca 10393b2e7f75SAl Viro static __always_inline 10403b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10411da177e4SLinus Torvalds { 1042ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10431cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1044fceef393SAl Viro struct inode *inode = nd->link_inode; 10456d7b5aaeSAl Viro int error; 10460a959df5SAl Viro const char *res; 10471da177e4SLinus Torvalds 10488fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10498fa9dd24SNeilBrown touch_atime(&last->link); 10508fa9dd24SNeilBrown cond_resched(); 1051c6718543SMiklos Szeredi } else if (atime_needs_update(&last->link, inode)) { 10524675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10538fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10548fa9dd24SNeilBrown touch_atime(&last->link); 10558fa9dd24SNeilBrown } 10568fa9dd24SNeilBrown 1057bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1058bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1059bda0be7aSNeilBrown if (unlikely(error)) 10606920a440SAl Viro return ERR_PTR(error); 106136f3b4f6SAl Viro 106286acdca1SAl Viro nd->last_type = LAST_BIND; 10634c4f7c19SEric Biggers res = READ_ONCE(inode->i_link); 1064d4dee48bSAl Viro if (!res) { 1065fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1066fceef393SAl Viro struct delayed_call *); 1067fceef393SAl Viro get = inode->i_op->get_link; 10688c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1069fceef393SAl Viro res = get(NULL, inode, &last->done); 10706b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10714675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10728c1b4566SAl Viro return ERR_PTR(-ECHILD); 1073fceef393SAl Viro res = get(dentry, inode, &last->done); 10748c1b4566SAl Viro } 10756b255391SAl Viro } else { 1076fceef393SAl Viro res = get(dentry, inode, &last->done); 10776b255391SAl Viro } 1078fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1079fab51e8aSAl Viro return res; 10800a959df5SAl Viro } 1081fab51e8aSAl Viro if (*res == '/') { 1082fab51e8aSAl Viro if (!nd->root.mnt) 1083fab51e8aSAl Viro set_root(nd); 1084248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1085fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1086fab51e8aSAl Viro while (unlikely(*++res == '/')) 1087fab51e8aSAl Viro ; 1088fab51e8aSAl Viro } 1089fab51e8aSAl Viro if (!*res) 1090fab51e8aSAl Viro res = NULL; 10910a959df5SAl Viro return res; 10920a959df5SAl Viro } 10936d7b5aaeSAl Viro 1094f015f126SDavid Howells /* 1095f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1096f015f126SDavid Howells * 1097f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1098f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1099f015f126SDavid Howells * Up is towards /. 1100f015f126SDavid Howells * 1101f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1102f015f126SDavid Howells * root. 1103f015f126SDavid Howells */ 1104bab77ebfSAl Viro int follow_up(struct path *path) 11051da177e4SLinus Torvalds { 11060714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11070714a533SAl Viro struct mount *parent; 11081da177e4SLinus Torvalds struct dentry *mountpoint; 110999b7db7bSNick Piggin 111048a066e7SAl Viro read_seqlock_excl(&mount_lock); 11110714a533SAl Viro parent = mnt->mnt_parent; 11123c0a6163SAl Viro if (parent == mnt) { 111348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11141da177e4SLinus Torvalds return 0; 11151da177e4SLinus Torvalds } 11160714a533SAl Viro mntget(&parent->mnt); 1117a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 111848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1119bab77ebfSAl Viro dput(path->dentry); 1120bab77ebfSAl Viro path->dentry = mountpoint; 1121bab77ebfSAl Viro mntput(path->mnt); 11220714a533SAl Viro path->mnt = &parent->mnt; 11231da177e4SLinus Torvalds return 1; 11241da177e4SLinus Torvalds } 11254d359507SAl Viro EXPORT_SYMBOL(follow_up); 11261da177e4SLinus Torvalds 1127b5c84bf6SNick Piggin /* 11289875cf80SDavid Howells * Perform an automount 11299875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11309875cf80SDavid Howells * were called with. 11311da177e4SLinus Torvalds */ 1132756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11339875cf80SDavid Howells bool *need_mntput) 113431e6b01fSNick Piggin { 11359875cf80SDavid Howells struct vfsmount *mnt; 1136ea5b778aSDavid Howells int err; 11379875cf80SDavid Howells 11389875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11399875cf80SDavid Howells return -EREMOTE; 11409875cf80SDavid Howells 11410ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11420ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11430ec26fd0SMiklos Szeredi * the name. 11440ec26fd0SMiklos Szeredi * 11450ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11465a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11470ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11480ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11490ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11500ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11515a30d8a2SDavid Howells */ 1152756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11535d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11545d38f049SIan Kent path->dentry->d_inode) 11559875cf80SDavid Howells return -EISDIR; 11560ec26fd0SMiklos Szeredi 1157756daf26SNeilBrown nd->total_link_count++; 1158756daf26SNeilBrown if (nd->total_link_count >= 40) 11599875cf80SDavid Howells return -ELOOP; 11609875cf80SDavid Howells 11619875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11629875cf80SDavid Howells if (IS_ERR(mnt)) { 11639875cf80SDavid Howells /* 11649875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11659875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11669875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11679875cf80SDavid Howells * 11689875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11699875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11709875cf80SDavid Howells * the path is inaccessible and we should say so. 11719875cf80SDavid Howells */ 1172756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11739875cf80SDavid Howells return -EREMOTE; 11749875cf80SDavid Howells return PTR_ERR(mnt); 117531e6b01fSNick Piggin } 1176ea5b778aSDavid Howells 11779875cf80SDavid Howells if (!mnt) /* mount collision */ 11789875cf80SDavid Howells return 0; 11799875cf80SDavid Howells 11808aef1884SAl Viro if (!*need_mntput) { 11818aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11828aef1884SAl Viro mntget(path->mnt); 11838aef1884SAl Viro *need_mntput = true; 11848aef1884SAl Viro } 118519a167afSAl Viro err = finish_automount(mnt, path); 1186ea5b778aSDavid Howells 1187ea5b778aSDavid Howells switch (err) { 1188ea5b778aSDavid Howells case -EBUSY: 1189ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 119019a167afSAl Viro return 0; 1191ea5b778aSDavid Howells case 0: 11928aef1884SAl Viro path_put(path); 11939875cf80SDavid Howells path->mnt = mnt; 11949875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11959875cf80SDavid Howells return 0; 119619a167afSAl Viro default: 119719a167afSAl Viro return err; 11989875cf80SDavid Howells } 119919a167afSAl Viro 1200ea5b778aSDavid Howells } 12019875cf80SDavid Howells 12029875cf80SDavid Howells /* 12039875cf80SDavid Howells * Handle a dentry that is managed in some way. 1204cc53ce53SDavid Howells * - Flagged for transit management (autofs) 12059875cf80SDavid Howells * - Flagged as mountpoint 12069875cf80SDavid Howells * - Flagged as automount point 12079875cf80SDavid Howells * 12089875cf80SDavid Howells * This may only be called in refwalk mode. 12099875cf80SDavid Howells * 12109875cf80SDavid Howells * Serialization is taken care of in namespace.c 12119875cf80SDavid Howells */ 1212756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12139875cf80SDavid Howells { 12148aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 12159875cf80SDavid Howells unsigned managed; 12169875cf80SDavid Howells bool need_mntput = false; 12178aef1884SAl Viro int ret = 0; 12189875cf80SDavid Howells 12199875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12209875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 12219875cf80SDavid Howells * the components of that value change under us */ 12226aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 12239875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 12249875cf80SDavid Howells unlikely(managed != 0)) { 1225cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1226cc53ce53SDavid Howells * being held. */ 1227cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1228cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1229cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1230fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1231cc53ce53SDavid Howells if (ret < 0) 12328aef1884SAl Viro break; 1233cc53ce53SDavid Howells } 1234cc53ce53SDavid Howells 12359875cf80SDavid Howells /* Transit to a mounted filesystem. */ 12369875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 12379875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12389875cf80SDavid Howells if (mounted) { 12399875cf80SDavid Howells dput(path->dentry); 12409875cf80SDavid Howells if (need_mntput) 1241463ffb2eSAl Viro mntput(path->mnt); 1242463ffb2eSAl Viro path->mnt = mounted; 1243463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12449875cf80SDavid Howells need_mntput = true; 12459875cf80SDavid Howells continue; 1246463ffb2eSAl Viro } 1247463ffb2eSAl Viro 12489875cf80SDavid Howells /* Something is mounted on this dentry in another 12499875cf80SDavid Howells * namespace and/or whatever was mounted there in this 125048a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 125148a066e7SAl Viro * get it */ 12521da177e4SLinus Torvalds } 12539875cf80SDavid Howells 12549875cf80SDavid Howells /* Handle an automount point */ 12559875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1256756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12579875cf80SDavid Howells if (ret < 0) 12588aef1884SAl Viro break; 12599875cf80SDavid Howells continue; 12609875cf80SDavid Howells } 12619875cf80SDavid Howells 12629875cf80SDavid Howells /* We didn't change the current path point */ 12639875cf80SDavid Howells break; 12649875cf80SDavid Howells } 12658aef1884SAl Viro 12668aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12678aef1884SAl Viro mntput(path->mnt); 1268e9742b53SAl Viro if (ret == -EISDIR || !ret) 1269e9742b53SAl Viro ret = 1; 12708402752eSAl Viro if (need_mntput) 12718402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12728402752eSAl Viro if (unlikely(ret < 0)) 12738402752eSAl Viro path_put_conditional(path, nd); 12748402752eSAl Viro return ret; 12751da177e4SLinus Torvalds } 12761da177e4SLinus Torvalds 1277cc53ce53SDavid Howells int follow_down_one(struct path *path) 12781da177e4SLinus Torvalds { 12791da177e4SLinus Torvalds struct vfsmount *mounted; 12801da177e4SLinus Torvalds 12811c755af4SAl Viro mounted = lookup_mnt(path); 12821da177e4SLinus Torvalds if (mounted) { 12839393bd07SAl Viro dput(path->dentry); 12849393bd07SAl Viro mntput(path->mnt); 12859393bd07SAl Viro path->mnt = mounted; 12869393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12871da177e4SLinus Torvalds return 1; 12881da177e4SLinus Torvalds } 12891da177e4SLinus Torvalds return 0; 12901da177e4SLinus Torvalds } 12914d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12921da177e4SLinus Torvalds 1293fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 129462a7375eSIan Kent { 1295fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1296fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 129762a7375eSIan Kent } 129862a7375eSIan Kent 12999875cf80SDavid Howells /* 1300287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1301287548e4SAl Viro * we meet a managed dentry that would need blocking. 13029875cf80SDavid Howells */ 13039875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1304254cf582SAl Viro struct inode **inode, unsigned *seqp) 13059875cf80SDavid Howells { 130662a7375eSIan Kent for (;;) { 1307c7105365SAl Viro struct mount *mounted; 130862a7375eSIan Kent /* 130962a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 131062a7375eSIan Kent * that wants to block transit. 131162a7375eSIan Kent */ 1312fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1313b8faf035SNeilBrown case -ECHILD: 1314b8faf035SNeilBrown default: 1315ab90911fSDavid Howells return false; 1316b8faf035SNeilBrown case -EISDIR: 1317b8faf035SNeilBrown return true; 1318b8faf035SNeilBrown case 0: 1319b8faf035SNeilBrown break; 1320b8faf035SNeilBrown } 132162a7375eSIan Kent 132262a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1323b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 132462a7375eSIan Kent 1325474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13269875cf80SDavid Howells if (!mounted) 13279875cf80SDavid Howells break; 1328c7105365SAl Viro path->mnt = &mounted->mnt; 1329c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1330a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1331254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 133259430262SLinus Torvalds /* 133359430262SLinus Torvalds * Update the inode too. We don't need to re-check the 133459430262SLinus Torvalds * dentry sequence number here after this d_inode read, 133559430262SLinus Torvalds * because a mount-point is always pinned. 133659430262SLinus Torvalds */ 133759430262SLinus Torvalds *inode = path->dentry->d_inode; 13389875cf80SDavid Howells } 1339f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1340b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1341287548e4SAl Viro } 1342287548e4SAl Viro 134331e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 134431e6b01fSNick Piggin { 13454023bfc9SAl Viro struct inode *inode = nd->inode; 134631e6b01fSNick Piggin 134731e6b01fSNick Piggin while (1) { 1348aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 134931e6b01fSNick Piggin break; 135031e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 135131e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 135231e6b01fSNick Piggin struct dentry *parent = old->d_parent; 135331e6b01fSNick Piggin unsigned seq; 135431e6b01fSNick Piggin 13554023bfc9SAl Viro inode = parent->d_inode; 135631e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1357aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1358aed434adSAl Viro return -ECHILD; 135931e6b01fSNick Piggin nd->path.dentry = parent; 136031e6b01fSNick Piggin nd->seq = seq; 1361397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1362397d425dSEric W. Biederman return -ENOENT; 136331e6b01fSNick Piggin break; 1364aed434adSAl Viro } else { 1365aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1366aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1367aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1368aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1369aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1370aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1371aed434adSAl Viro return -ECHILD; 1372aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 137331e6b01fSNick Piggin break; 1374aed434adSAl Viro /* we know that mountpoint was pinned */ 1375aed434adSAl Viro nd->path.dentry = mountpoint; 1376aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1377aed434adSAl Viro inode = inode2; 1378aed434adSAl Viro nd->seq = seq; 137931e6b01fSNick Piggin } 1380aed434adSAl Viro } 1381aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1382b37199e6SAl Viro struct mount *mounted; 1383b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1384aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1385aed434adSAl Viro return -ECHILD; 1386b37199e6SAl Viro if (!mounted) 1387b37199e6SAl Viro break; 1388b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1389b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13904023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1391b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1392b37199e6SAl Viro } 13934023bfc9SAl Viro nd->inode = inode; 139431e6b01fSNick Piggin return 0; 139531e6b01fSNick Piggin } 139631e6b01fSNick Piggin 13979875cf80SDavid Howells /* 1398cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1399cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1400cc53ce53SDavid Howells * caller is permitted to proceed or not. 1401cc53ce53SDavid Howells */ 14027cc90cc3SAl Viro int follow_down(struct path *path) 1403cc53ce53SDavid Howells { 1404cc53ce53SDavid Howells unsigned managed; 1405cc53ce53SDavid Howells int ret; 1406cc53ce53SDavid Howells 14076aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1408cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1409cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1410cc53ce53SDavid Howells * being held. 1411cc53ce53SDavid Howells * 1412cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1413cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1414cc53ce53SDavid Howells * other than its daemon the right to mount on its 1415cc53ce53SDavid Howells * superstructure. 1416cc53ce53SDavid Howells * 1417cc53ce53SDavid Howells * The filesystem may sleep at this point. 1418cc53ce53SDavid Howells */ 1419cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1420cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1421cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1422fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1423cc53ce53SDavid Howells if (ret < 0) 1424cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1425cc53ce53SDavid Howells } 1426cc53ce53SDavid Howells 1427cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1428cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1429cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1430cc53ce53SDavid Howells if (!mounted) 1431cc53ce53SDavid Howells break; 1432cc53ce53SDavid Howells dput(path->dentry); 1433cc53ce53SDavid Howells mntput(path->mnt); 1434cc53ce53SDavid Howells path->mnt = mounted; 1435cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1436cc53ce53SDavid Howells continue; 1437cc53ce53SDavid Howells } 1438cc53ce53SDavid Howells 1439cc53ce53SDavid Howells /* Don't handle automount points here */ 1440cc53ce53SDavid Howells break; 1441cc53ce53SDavid Howells } 1442cc53ce53SDavid Howells return 0; 1443cc53ce53SDavid Howells } 14444d359507SAl Viro EXPORT_SYMBOL(follow_down); 1445cc53ce53SDavid Howells 1446cc53ce53SDavid Howells /* 14479875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14489875cf80SDavid Howells */ 14499875cf80SDavid Howells static void follow_mount(struct path *path) 14509875cf80SDavid Howells { 14519875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14529875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14539875cf80SDavid Howells if (!mounted) 14549875cf80SDavid Howells break; 14559875cf80SDavid Howells dput(path->dentry); 14569875cf80SDavid Howells mntput(path->mnt); 14579875cf80SDavid Howells path->mnt = mounted; 14589875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14599875cf80SDavid Howells } 14609875cf80SDavid Howells } 14619875cf80SDavid Howells 1462eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1463eedf265aSEric W. Biederman { 1464eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1465eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1466eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1467eedf265aSEric W. Biederman dput(old); 1468eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1469eedf265aSEric W. Biederman return -ENOENT; 1470eedf265aSEric W. Biederman return 0; 1471eedf265aSEric W. Biederman } 1472eedf265aSEric W. Biederman 1473397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14741da177e4SLinus Torvalds { 14751da177e4SLinus Torvalds while(1) { 1476030c7e0bSDanilo Krummrich if (path_equal(&nd->path, &nd->root)) 14771da177e4SLinus Torvalds break; 14784ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1479eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1480eedf265aSEric W. Biederman if (ret) 1481eedf265aSEric W. Biederman return ret; 14821da177e4SLinus Torvalds break; 14831da177e4SLinus Torvalds } 14843088dd70SAl Viro if (!follow_up(&nd->path)) 14851da177e4SLinus Torvalds break; 14861da177e4SLinus Torvalds } 148779ed0226SAl Viro follow_mount(&nd->path); 148831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1489397d425dSEric W. Biederman return 0; 14901da177e4SLinus Torvalds } 14911da177e4SLinus Torvalds 14921da177e4SLinus Torvalds /* 1493f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1494f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1495baa03890SNick Piggin */ 1496e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1497e3c13928SAl Viro struct dentry *dir, 14986c51e513SAl Viro unsigned int flags) 1499baa03890SNick Piggin { 1500a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1501bad61189SMiklos Szeredi if (dentry) { 1502a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1503bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 150474ff0ffcSAl Viro if (!error) 15055542aa2fSEric W. Biederman d_invalidate(dentry); 1506bad61189SMiklos Szeredi dput(dentry); 150774ff0ffcSAl Viro return ERR_PTR(error); 1508bad61189SMiklos Szeredi } 1509bad61189SMiklos Szeredi } 1510baa03890SNick Piggin return dentry; 1511baa03890SNick Piggin } 1512baa03890SNick Piggin 1513baa03890SNick Piggin /* 1514a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1515a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1516a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1517a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1518a03ece5fSAl Viro * at all. 151944396f4bSJosef Bacik */ 1520a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1521a03ece5fSAl Viro struct dentry *base, unsigned int flags) 152244396f4bSJosef Bacik { 1523a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 152444396f4bSJosef Bacik struct dentry *old; 1525a03ece5fSAl Viro struct inode *dir = base->d_inode; 1526a03ece5fSAl Viro 1527a03ece5fSAl Viro if (dentry) 1528a03ece5fSAl Viro return dentry; 152944396f4bSJosef Bacik 153044396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1531a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 153244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1533a03ece5fSAl Viro 1534a03ece5fSAl Viro dentry = d_alloc(base, name); 1535a03ece5fSAl Viro if (unlikely(!dentry)) 1536a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 153744396f4bSJosef Bacik 153872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 153944396f4bSJosef Bacik if (unlikely(old)) { 154044396f4bSJosef Bacik dput(dentry); 154144396f4bSJosef Bacik dentry = old; 154244396f4bSJosef Bacik } 154344396f4bSJosef Bacik return dentry; 154444396f4bSJosef Bacik } 154544396f4bSJosef Bacik 1546e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1547254cf582SAl Viro struct path *path, struct inode **inode, 1548254cf582SAl Viro unsigned *seqp) 15491da177e4SLinus Torvalds { 15504ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 155131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15525a18fff2SAl Viro int status = 1; 15539875cf80SDavid Howells int err; 15549875cf80SDavid Howells 15553cac260aSAl Viro /* 1556b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15575d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15585d0f49c1SAl Viro * going to fall back to non-racy lookup. 1559b04f784eSNick Piggin */ 156031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 156131e6b01fSNick Piggin unsigned seq; 1562766c4cbfSAl Viro bool negative; 1563da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15645d0f49c1SAl Viro if (unlikely(!dentry)) { 15654675ac39SAl Viro if (unlazy_walk(nd)) 15665d0f49c1SAl Viro return -ECHILD; 1567e9742b53SAl Viro return 0; 15685d0f49c1SAl Viro } 15695a18fff2SAl Viro 157012f8ad4bSLinus Torvalds /* 157112f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 157212f8ad4bSLinus Torvalds * the dentry name information from lookup. 157312f8ad4bSLinus Torvalds */ 157463afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1575766c4cbfSAl Viro negative = d_is_negative(dentry); 15765d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 157712f8ad4bSLinus Torvalds return -ECHILD; 157812f8ad4bSLinus Torvalds 157912f8ad4bSLinus Torvalds /* 158012f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 158112f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 158212f8ad4bSLinus Torvalds * 158312f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 158412f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 158512f8ad4bSLinus Torvalds */ 15865d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 158731e6b01fSNick Piggin return -ECHILD; 15885a18fff2SAl Viro 1589254cf582SAl Viro *seqp = seq; 15904ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1591209a7fb2SAl Viro if (likely(status > 0)) { 1592daf3761cSTrond Myklebust /* 1593daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1594daf3761cSTrond Myklebust * case that drops it. 1595daf3761cSTrond Myklebust */ 15965d0f49c1SAl Viro if (unlikely(negative)) 1597daf3761cSTrond Myklebust return -ENOENT; 159831e6b01fSNick Piggin path->mnt = mnt; 159931e6b01fSNick Piggin path->dentry = dentry; 1600254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1601e9742b53SAl Viro return 1; 16025d0f49c1SAl Viro } 16034675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1604254cf582SAl Viro return -ECHILD; 1605209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1606209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1607209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16085a18fff2SAl Viro } else { 1609e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 161081e6f520SAl Viro if (unlikely(!dentry)) 1611e9742b53SAl Viro return 0; 16124ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16135d0f49c1SAl Viro } 16145a18fff2SAl Viro if (unlikely(status <= 0)) { 1615e9742b53SAl Viro if (!status) 16165d0f49c1SAl Viro d_invalidate(dentry); 16175a18fff2SAl Viro dput(dentry); 16185a18fff2SAl Viro return status; 16195a18fff2SAl Viro } 1620766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1621766c4cbfSAl Viro dput(dentry); 1622766c4cbfSAl Viro return -ENOENT; 1623766c4cbfSAl Viro } 16245d0f49c1SAl Viro 16251da177e4SLinus Torvalds path->mnt = mnt; 16261da177e4SLinus Torvalds path->dentry = dentry; 1627756daf26SNeilBrown err = follow_managed(path, nd); 1628e9742b53SAl Viro if (likely(err > 0)) 162963afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16308402752eSAl Viro return err; 1631697f514dSMiklos Szeredi } 1632697f514dSMiklos Szeredi 1633697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 163488d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1635e3c13928SAl Viro struct dentry *dir, 1636e3c13928SAl Viro unsigned int flags) 1637697f514dSMiklos Szeredi { 163888d8331aSAl Viro struct dentry *dentry, *old; 16391936386eSAl Viro struct inode *inode = dir->d_inode; 1640d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16411936386eSAl Viro 16421936386eSAl Viro /* Don't go there if it's already dead */ 164394bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 164488d8331aSAl Viro return ERR_PTR(-ENOENT); 164594bdd655SAl Viro again: 1646d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 164794bdd655SAl Viro if (IS_ERR(dentry)) 164888d8331aSAl Viro return dentry; 164994bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1650a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1651949a852eSAl Viro int error = d_revalidate(dentry, flags); 1652949a852eSAl Viro if (unlikely(error <= 0)) { 165394bdd655SAl Viro if (!error) { 1654949a852eSAl Viro d_invalidate(dentry); 1655949a852eSAl Viro dput(dentry); 165694bdd655SAl Viro goto again; 165794bdd655SAl Viro } 165894bdd655SAl Viro dput(dentry); 1659949a852eSAl Viro dentry = ERR_PTR(error); 1660949a852eSAl Viro } 1661949a852eSAl Viro } 166294bdd655SAl Viro } else { 16631936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 166485c7f810SAl Viro d_lookup_done(dentry); 16651936386eSAl Viro if (unlikely(old)) { 16661936386eSAl Viro dput(dentry); 16671936386eSAl Viro dentry = old; 1668949a852eSAl Viro } 1669949a852eSAl Viro } 1670e3c13928SAl Viro return dentry; 16711da177e4SLinus Torvalds } 16721da177e4SLinus Torvalds 167388d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 167488d8331aSAl Viro struct dentry *dir, 167588d8331aSAl Viro unsigned int flags) 167688d8331aSAl Viro { 167788d8331aSAl Viro struct inode *inode = dir->d_inode; 167888d8331aSAl Viro struct dentry *res; 167988d8331aSAl Viro inode_lock_shared(inode); 168088d8331aSAl Viro res = __lookup_slow(name, dir, flags); 168188d8331aSAl Viro inode_unlock_shared(inode); 168288d8331aSAl Viro return res; 168388d8331aSAl Viro } 168488d8331aSAl Viro 168552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 168652094c8aSAl Viro { 168752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16884ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 168952094c8aSAl Viro if (err != -ECHILD) 169052094c8aSAl Viro return err; 16914675ac39SAl Viro if (unlazy_walk(nd)) 169252094c8aSAl Viro return -ECHILD; 169352094c8aSAl Viro } 16944ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 169552094c8aSAl Viro } 169652094c8aSAl Viro 16979856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16989856fa1bSAl Viro { 16999856fa1bSAl Viro if (type == LAST_DOTDOT) { 17009e6697e2SAl Viro if (!nd->root.mnt) 17019e6697e2SAl Viro set_root(nd); 17029856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 170370291aecSAl Viro return follow_dotdot_rcu(nd); 17049856fa1bSAl Viro } else 1705397d425dSEric W. Biederman return follow_dotdot(nd); 17069856fa1bSAl Viro } 17079856fa1bSAl Viro return 0; 17089856fa1bSAl Viro } 17099856fa1bSAl Viro 1710181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1711181548c0SAl Viro struct inode *inode, unsigned seq) 1712d63ff28fSAl Viro { 1713626de996SAl Viro int error; 17141cf2665bSAl Viro struct saved *last; 1715756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1716626de996SAl Viro path_to_nameidata(link, nd); 1717626de996SAl Viro return -ELOOP; 1718626de996SAl Viro } 1719bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1720cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1721cd179f44SAl Viro mntget(link->mnt); 17227973387aSAl Viro } 1723626de996SAl Viro error = nd_alloc_stack(nd); 1724626de996SAl Viro if (unlikely(error)) { 1725bc40aee0SAl Viro if (error == -ECHILD) { 1726ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1727ad1633a1SAl Viro drop_links(nd); 1728ad1633a1SAl Viro nd->depth = 0; 1729ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1730ad1633a1SAl Viro nd->path.mnt = NULL; 1731ad1633a1SAl Viro nd->path.dentry = NULL; 1732ad1633a1SAl Viro rcu_read_unlock(); 17334675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1734bc40aee0SAl Viro error = nd_alloc_stack(nd); 1735bc40aee0SAl Viro } 1736bc40aee0SAl Viro if (error) { 1737cd179f44SAl Viro path_put(link); 1738626de996SAl Viro return error; 1739626de996SAl Viro } 1740bc40aee0SAl Viro } 1741626de996SAl Viro 1742ab104923SAl Viro last = nd->stack + nd->depth++; 17431cf2665bSAl Viro last->link = *link; 1744fceef393SAl Viro clear_delayed_call(&last->done); 1745fceef393SAl Viro nd->link_inode = inode; 17460450b2d1SAl Viro last->seq = seq; 1747d63ff28fSAl Viro return 1; 1748d63ff28fSAl Viro } 1749d63ff28fSAl Viro 17508f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 175131d66bcdSAl Viro 17523ddcd056SLinus Torvalds /* 17533ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17543ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17553ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17563ddcd056SLinus Torvalds * for the common case. 17573ddcd056SLinus Torvalds */ 17588f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17598f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17603ddcd056SLinus Torvalds { 176131d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 176231d66bcdSAl Viro put_link(nd); 17638f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17648f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17658f64fb1cSAl Viro /* not a symlink or should not follow */ 17668f64fb1cSAl Viro path_to_nameidata(path, nd); 17678f64fb1cSAl Viro nd->inode = inode; 17688f64fb1cSAl Viro nd->seq = seq; 1769d63ff28fSAl Viro return 0; 17708f64fb1cSAl Viro } 1771a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1772a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17738f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1774a7f77542SAl Viro return -ECHILD; 1775a7f77542SAl Viro } 17768f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17773ddcd056SLinus Torvalds } 17783ddcd056SLinus Torvalds 17794693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1780ce57dfc1SAl Viro { 1781caa85634SAl Viro struct path path; 1782ce57dfc1SAl Viro struct inode *inode; 1783254cf582SAl Viro unsigned seq; 1784ce57dfc1SAl Viro int err; 1785ce57dfc1SAl Viro /* 1786ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1787ce57dfc1SAl Viro * to be able to know about the current root directory and 1788ce57dfc1SAl Viro * parent relationships. 1789ce57dfc1SAl Viro */ 17904693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17914693a547SAl Viro err = handle_dots(nd, nd->last_type); 17921c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17934693a547SAl Viro put_link(nd); 17944693a547SAl Viro return err; 17954693a547SAl Viro } 1796254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1797e9742b53SAl Viro if (unlikely(err <= 0)) { 1798697f514dSMiklos Szeredi if (err < 0) 1799f0a9ba70SAl Viro return err; 1800e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1801e3c13928SAl Viro nd->flags); 1802e3c13928SAl Viro if (IS_ERR(path.dentry)) 1803e3c13928SAl Viro return PTR_ERR(path.dentry); 18047500c38aSAl Viro 1805e3c13928SAl Viro path.mnt = nd->path.mnt; 1806e3c13928SAl Viro err = follow_managed(&path, nd); 1807e3c13928SAl Viro if (unlikely(err < 0)) 1808f0a9ba70SAl Viro return err; 1809697f514dSMiklos Szeredi 18107500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 18117500c38aSAl Viro path_to_nameidata(&path, nd); 18127500c38aSAl Viro return -ENOENT; 18137500c38aSAl Viro } 18147500c38aSAl Viro 1815254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1816d4565649SAl Viro inode = d_backing_inode(path.dentry); 1817766c4cbfSAl Viro } 1818697f514dSMiklos Szeredi 18198f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1820ce57dfc1SAl Viro } 1821ce57dfc1SAl Viro 18221da177e4SLinus Torvalds /* 1823bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1824bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1825bfcfaa77SLinus Torvalds * 1826bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1827bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1828bfcfaa77SLinus Torvalds * fast. 1829bfcfaa77SLinus Torvalds * 1830bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1831bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1832bfcfaa77SLinus Torvalds * crossing operation. 1833bfcfaa77SLinus Torvalds * 1834bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1835bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1836bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1837bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1838bfcfaa77SLinus Torvalds */ 1839bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1840bfcfaa77SLinus Torvalds 1841f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1842bfcfaa77SLinus Torvalds 1843468a9428SGeorge Spelvin #ifdef HASH_MIX 1844bfcfaa77SLinus Torvalds 1845468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1846468a9428SGeorge Spelvin 1847468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18482a18da7aSGeorge Spelvin /* 18492a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18502a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18512a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18522a18da7aSGeorge Spelvin * and no temporaries. 18532a18da7aSGeorge Spelvin * 18542a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18552a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18562a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18572a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18582a18da7aSGeorge Spelvin * 18592a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18602a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18612a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18622a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18632a18da7aSGeorge Spelvin * 18642a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18652a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18662a18da7aSGeorge Spelvin * toggling any given output bit. 18672a18da7aSGeorge Spelvin * 18682a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18692a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18702a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18712a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18722a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18732a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18742a18da7aSGeorge Spelvin * Perfect: 8192 258048 18752a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18762a18da7aSGeorge Spelvin */ 18772a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18782a18da7aSGeorge Spelvin ( x ^= (a), \ 18792a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18802a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18812a18da7aSGeorge Spelvin y *= 9 ) 1882bfcfaa77SLinus Torvalds 18830fed3ac8SGeorge Spelvin /* 18842a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18852a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18862a18da7aSGeorge Spelvin * work done before the hash value is used. 18870fed3ac8SGeorge Spelvin */ 18882a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18890fed3ac8SGeorge Spelvin { 18902a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18912a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18922a18da7aSGeorge Spelvin return y >> 32; 18930fed3ac8SGeorge Spelvin } 18940fed3ac8SGeorge Spelvin 1895bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1896bfcfaa77SLinus Torvalds 18972a18da7aSGeorge Spelvin /* 18982a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18992a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19002a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19012a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19022a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19032a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19042a18da7aSGeorge Spelvin * Perfect: 2048 31744 19052a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19062a18da7aSGeorge Spelvin */ 19072a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19082a18da7aSGeorge Spelvin ( x ^= (a), \ 19092a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19102a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19112a18da7aSGeorge Spelvin y *= 9 ) 1912bfcfaa77SLinus Torvalds 19132a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19140fed3ac8SGeorge Spelvin { 19152a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19162a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19170fed3ac8SGeorge Spelvin } 19180fed3ac8SGeorge Spelvin 1919bfcfaa77SLinus Torvalds #endif 1920bfcfaa77SLinus Torvalds 19212a18da7aSGeorge Spelvin /* 19222a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19232a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19242a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19252a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19262a18da7aSGeorge Spelvin * finds the delimiter after the name. 19272a18da7aSGeorge Spelvin */ 19288387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1929bfcfaa77SLinus Torvalds { 19308387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1931bfcfaa77SLinus Torvalds 1932bfcfaa77SLinus Torvalds for (;;) { 1933fcfd2fbfSGeorge Spelvin if (!len) 1934fcfd2fbfSGeorge Spelvin goto done; 1935e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1936bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1937bfcfaa77SLinus Torvalds break; 19382a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1939bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1940bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1941bfcfaa77SLinus Torvalds } 19422a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1943bfcfaa77SLinus Torvalds done: 19442a18da7aSGeorge Spelvin return fold_hash(x, y); 1945bfcfaa77SLinus Torvalds } 1946bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1947bfcfaa77SLinus Torvalds 1948fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19498387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1950fcfd2fbfSGeorge Spelvin { 19518387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19528387ff25SLinus Torvalds unsigned long adata, mask, len; 1953fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1954fcfd2fbfSGeorge Spelvin 19558387ff25SLinus Torvalds len = 0; 19568387ff25SLinus Torvalds goto inside; 19578387ff25SLinus Torvalds 1958fcfd2fbfSGeorge Spelvin do { 19592a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1960fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19618387ff25SLinus Torvalds inside: 1962fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1963fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1964fcfd2fbfSGeorge Spelvin 1965fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1966fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19672a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1968fcfd2fbfSGeorge Spelvin 19692a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1970fcfd2fbfSGeorge Spelvin } 1971fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1972fcfd2fbfSGeorge Spelvin 1973bfcfaa77SLinus Torvalds /* 1974bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1975d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1976bfcfaa77SLinus Torvalds */ 19778387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1978bfcfaa77SLinus Torvalds { 19798387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19808387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 198136126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1982bfcfaa77SLinus Torvalds 19838387ff25SLinus Torvalds len = 0; 19848387ff25SLinus Torvalds goto inside; 19858387ff25SLinus Torvalds 1986bfcfaa77SLinus Torvalds do { 19872a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1988bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19898387ff25SLinus Torvalds inside: 1990e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 199136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 199236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1993bfcfaa77SLinus Torvalds 199436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 199536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 199636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19972a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 199836126f8fSLinus Torvalds 19992a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2000bfcfaa77SLinus Torvalds } 2001bfcfaa77SLinus Torvalds 20022a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2003bfcfaa77SLinus Torvalds 2004fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20058387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20060145acc2SLinus Torvalds { 20078387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20080145acc2SLinus Torvalds while (len--) 2009fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20100145acc2SLinus Torvalds return end_name_hash(hash); 20110145acc2SLinus Torvalds } 2012ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20130145acc2SLinus Torvalds 2014fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20158387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2016fcfd2fbfSGeorge Spelvin { 20178387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2018fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2019fcfd2fbfSGeorge Spelvin 2020fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2021e0ab7af9SGeorge Spelvin while (c) { 2022fcfd2fbfSGeorge Spelvin len++; 2023fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2024fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2025e0ab7af9SGeorge Spelvin } 2026fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2027fcfd2fbfSGeorge Spelvin } 2028f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2029fcfd2fbfSGeorge Spelvin 20303ddcd056SLinus Torvalds /* 2031200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2032200e9ef7SLinus Torvalds * one character. 2033200e9ef7SLinus Torvalds */ 20348387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2035200e9ef7SLinus Torvalds { 20368387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2037200e9ef7SLinus Torvalds unsigned long len = 0, c; 2038200e9ef7SLinus Torvalds 2039200e9ef7SLinus Torvalds c = (unsigned char)*name; 2040200e9ef7SLinus Torvalds do { 2041200e9ef7SLinus Torvalds len++; 2042200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2043200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2044200e9ef7SLinus Torvalds } while (c && c != '/'); 2045d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2046200e9ef7SLinus Torvalds } 2047200e9ef7SLinus Torvalds 2048bfcfaa77SLinus Torvalds #endif 2049bfcfaa77SLinus Torvalds 2050200e9ef7SLinus Torvalds /* 20511da177e4SLinus Torvalds * Name resolution. 2052ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2053ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20541da177e4SLinus Torvalds * 2055ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2056ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20571da177e4SLinus Torvalds */ 20586de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20591da177e4SLinus Torvalds { 20601da177e4SLinus Torvalds int err; 20611da177e4SLinus Torvalds 20629b5858e9SAl Viro if (IS_ERR(name)) 20639b5858e9SAl Viro return PTR_ERR(name); 20641da177e4SLinus Torvalds while (*name=='/') 20651da177e4SLinus Torvalds name++; 20661da177e4SLinus Torvalds if (!*name) 20679e18f10aSAl Viro return 0; 20681da177e4SLinus Torvalds 20691da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20701da177e4SLinus Torvalds for(;;) { 2071d6bb3e90SLinus Torvalds u64 hash_len; 2072fe479a58SAl Viro int type; 20731da177e4SLinus Torvalds 207452094c8aSAl Viro err = may_lookup(nd); 20751da177e4SLinus Torvalds if (err) 20763595e234SAl Viro return err; 20771da177e4SLinus Torvalds 20788387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20791da177e4SLinus Torvalds 2080fe479a58SAl Viro type = LAST_NORM; 2081d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2082fe479a58SAl Viro case 2: 2083200e9ef7SLinus Torvalds if (name[1] == '.') { 2084fe479a58SAl Viro type = LAST_DOTDOT; 208516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 208616c2cd71SAl Viro } 2087fe479a58SAl Viro break; 2088fe479a58SAl Viro case 1: 2089fe479a58SAl Viro type = LAST_DOT; 2090fe479a58SAl Viro } 20915a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20925a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 209316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20945a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2095a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2096da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20975a202bcdSAl Viro if (err < 0) 20983595e234SAl Viro return err; 2099d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2100d6bb3e90SLinus Torvalds name = this.name; 21015a202bcdSAl Viro } 21025a202bcdSAl Viro } 2103fe479a58SAl Viro 2104d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2105d6bb3e90SLinus Torvalds nd->last.name = name; 21065f4a6a69SAl Viro nd->last_type = type; 21075f4a6a69SAl Viro 2108d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2109d6bb3e90SLinus Torvalds if (!*name) 2110bdf6cbf1SAl Viro goto OK; 2111200e9ef7SLinus Torvalds /* 2112200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2113200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2114200e9ef7SLinus Torvalds */ 2115200e9ef7SLinus Torvalds do { 2116d6bb3e90SLinus Torvalds name++; 2117d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21188620c238SAl Viro if (unlikely(!*name)) { 21198620c238SAl Viro OK: 2120368ee9baSAl Viro /* pathname body, done */ 21218620c238SAl Viro if (!nd->depth) 21228620c238SAl Viro return 0; 21238620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2124368ee9baSAl Viro /* trailing symlink, done */ 21258620c238SAl Viro if (!name) 21268620c238SAl Viro return 0; 21278620c238SAl Viro /* last component of nested symlink */ 21288f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 21291c4ff1a8SAl Viro } else { 21301c4ff1a8SAl Viro /* not the last component */ 21318f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 21328620c238SAl Viro } 2133ce57dfc1SAl Viro if (err < 0) 21343595e234SAl Viro return err; 2135fe479a58SAl Viro 2136ce57dfc1SAl Viro if (err) { 2137626de996SAl Viro const char *s = get_link(nd); 21385a460275SAl Viro 2139a1c83681SViresh Kumar if (IS_ERR(s)) 21403595e234SAl Viro return PTR_ERR(s); 2141172a39a0SAl Viro err = 0; 214212b09578SAl Viro if (unlikely(!s)) { 214312b09578SAl Viro /* jumped */ 2144b9ff4429SAl Viro put_link(nd); 214512b09578SAl Viro } else { 2146071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 214732cd7468SAl Viro name = s; 21489e18f10aSAl Viro continue; 214948c8b0c5SAl Viro } 215031e6b01fSNick Piggin } 215197242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 215297242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21534675ac39SAl Viro if (unlazy_walk(nd)) 215497242f99SAl Viro return -ECHILD; 215597242f99SAl Viro } 21563595e234SAl Viro return -ENOTDIR; 21575f4a6a69SAl Viro } 2158ce57dfc1SAl Viro } 215997242f99SAl Viro } 21601da177e4SLinus Torvalds 2161edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2162c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 216331e6b01fSNick Piggin { 2164c8a53ee5SAl Viro const char *s = nd->name->name; 216531e6b01fSNick Piggin 2166c0eb027eSLinus Torvalds if (!*s) 2167c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2168edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2169edc2b1daSAl Viro rcu_read_lock(); 2170c0eb027eSLinus Torvalds 217131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2172980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 217331e6b01fSNick Piggin nd->depth = 0; 21745b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2175b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2176b18825a7SDavid Howells struct inode *inode = root->d_inode; 217793893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2178368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21795b6ca027SAl Viro nd->path = nd->root; 21805b6ca027SAl Viro nd->inode = inode; 21815b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21825b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21838f47a016SAl Viro nd->root_seq = nd->seq; 218448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21855b6ca027SAl Viro } else { 21865b6ca027SAl Viro path_get(&nd->path); 21875b6ca027SAl Viro } 2188368ee9baSAl Viro return s; 21895b6ca027SAl Viro } 21905b6ca027SAl Viro 219131e6b01fSNick Piggin nd->root.mnt = NULL; 2192248fb5b9SAl Viro nd->path.mnt = NULL; 2193248fb5b9SAl Viro nd->path.dentry = NULL; 219431e6b01fSNick Piggin 219548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2196fd2f7cb5SAl Viro if (*s == '/') { 2197e41f7d4eSAl Viro set_root(nd); 2198248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2199ef55d917SAl Viro return s; 2200ef55d917SAl Viro return ERR_PTR(-ECHILD); 2201c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2202e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 220331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2204c28cc364SNick Piggin unsigned seq; 220531e6b01fSNick Piggin 2206c28cc364SNick Piggin do { 2207c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 220831e6b01fSNick Piggin nd->path = fs->pwd; 2209ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2210c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2211c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2212e41f7d4eSAl Viro } else { 2213e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2214ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2215e41f7d4eSAl Viro } 2216ef55d917SAl Viro return s; 221731e6b01fSNick Piggin } else { 2218582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2219c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 222031e6b01fSNick Piggin struct dentry *dentry; 222131e6b01fSNick Piggin 22222903ff01SAl Viro if (!f.file) 2223368ee9baSAl Viro return ERR_PTR(-EBADF); 222431e6b01fSNick Piggin 22252903ff01SAl Viro dentry = f.file->f_path.dentry; 222631e6b01fSNick Piggin 2227edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22282903ff01SAl Viro fdput(f); 2229368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2230f52e0c11SAl Viro } 22312903ff01SAl Viro 22322903ff01SAl Viro nd->path = f.file->f_path; 2233e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 223434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 223534a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22365590ff0dSUlrich Drepper } else { 22372903ff01SAl Viro path_get(&nd->path); 223834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22391da177e4SLinus Torvalds } 224034a26b99SAl Viro fdput(f); 2241368ee9baSAl Viro return s; 2242e41f7d4eSAl Viro } 22439b4a9b14SAl Viro } 22449b4a9b14SAl Viro 22453bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 224695fa25d9SAl Viro { 224795fa25d9SAl Viro const char *s; 2248fec2fa24SAl Viro int error = may_follow_link(nd); 2249deb106c6SAl Viro if (unlikely(error)) 22503bdba28bSAl Viro return ERR_PTR(error); 225195fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2252fab51e8aSAl Viro nd->stack[0].name = NULL; 22533b2e7f75SAl Viro s = get_link(nd); 2254deb106c6SAl Viro return s ? s : ""; 225595fa25d9SAl Viro } 225695fa25d9SAl Viro 2257caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2258bd92d7feSAl Viro { 2259bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2260bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2261bd92d7feSAl Viro 2262bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22631c4ff1a8SAl Viro return walk_component(nd, 0); 2264bd92d7feSAl Viro } 2265bd92d7feSAl Viro 22664f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22674f757f3cSAl Viro { 22684f757f3cSAl Viro struct path path = nd->path; 22694f757f3cSAl Viro struct inode *inode = nd->inode; 22704f757f3cSAl Viro unsigned seq = nd->seq; 22714f757f3cSAl Viro int err; 22724f757f3cSAl Viro 22734f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22744f757f3cSAl Viro /* 22754f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22764f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22774f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22784f757f3cSAl Viro */ 22794f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22804f757f3cSAl Viro return -ECHILD; 22814f757f3cSAl Viro } else { 22824f757f3cSAl Viro dget(path.dentry); 22834f757f3cSAl Viro err = follow_managed(&path, nd); 22844f757f3cSAl Viro if (unlikely(err < 0)) 22854f757f3cSAl Viro return err; 22864f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22874f757f3cSAl Viro seq = 0; 22884f757f3cSAl Viro } 22894f757f3cSAl Viro path_to_nameidata(&path, nd); 22904f757f3cSAl Viro nd->inode = inode; 22914f757f3cSAl Viro nd->seq = seq; 22924f757f3cSAl Viro return 0; 22934f757f3cSAl Viro } 22944f757f3cSAl Viro 22959b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2296c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22979b4a9b14SAl Viro { 2298c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2299bd92d7feSAl Viro int err; 230031e6b01fSNick Piggin 23019b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23024f757f3cSAl Viro err = handle_lookup_down(nd); 23035f336e72SAl Viro if (unlikely(err < 0)) 23045f336e72SAl Viro s = ERR_PTR(err); 23054f757f3cSAl Viro } 23064f757f3cSAl Viro 23073bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 23083bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 23093bdba28bSAl Viro s = trailing_symlink(nd); 2310bd92d7feSAl Viro } 23119f1fafeeSAl Viro if (!err) 23129f1fafeeSAl Viro err = complete_walk(nd); 2313bd92d7feSAl Viro 2314deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2315deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2316bd23a539SAl Viro err = -ENOTDIR; 2317625b6d10SAl Viro if (!err) { 2318625b6d10SAl Viro *path = nd->path; 2319625b6d10SAl Viro nd->path.mnt = NULL; 2320625b6d10SAl Viro nd->path.dentry = NULL; 2321625b6d10SAl Viro } 2322deb106c6SAl Viro terminate_walk(nd); 2323bd92d7feSAl Viro return err; 232431e6b01fSNick Piggin } 232531e6b01fSNick Piggin 232631d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23279ad1aaa6SAl Viro struct path *path, struct path *root) 2328873f1eedSJeff Layton { 2329894bc8c4SAl Viro int retval; 23309883d185SAl Viro struct nameidata nd; 2331abc9f5beSAl Viro if (IS_ERR(name)) 2332abc9f5beSAl Viro return PTR_ERR(name); 23339ad1aaa6SAl Viro if (unlikely(root)) { 23349ad1aaa6SAl Viro nd.root = *root; 23359ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23369ad1aaa6SAl Viro } 23379883d185SAl Viro set_nameidata(&nd, dfd, name); 2338c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2339873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2340c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2341873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2342c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2343873f1eedSJeff Layton 2344873f1eedSJeff Layton if (likely(!retval)) 2345ff0ebee2SAl Viro audit_inode(name, path->dentry, 0); 23469883d185SAl Viro restore_nameidata(); 2347e4bd1c1aSAl Viro putname(name); 2348873f1eedSJeff Layton return retval; 2349873f1eedSJeff Layton } 2350873f1eedSJeff Layton 23518bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2352c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2353391172c4SAl Viro struct path *parent) 23548bcb77faSAl Viro { 2355c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23569b5858e9SAl Viro int err = link_path_walk(s, nd); 23578bcb77faSAl Viro if (!err) 23588bcb77faSAl Viro err = complete_walk(nd); 2359391172c4SAl Viro if (!err) { 2360391172c4SAl Viro *parent = nd->path; 2361391172c4SAl Viro nd->path.mnt = NULL; 2362391172c4SAl Viro nd->path.dentry = NULL; 2363391172c4SAl Viro } 2364deb106c6SAl Viro terminate_walk(nd); 23658bcb77faSAl Viro return err; 23668bcb77faSAl Viro } 23678bcb77faSAl Viro 23685c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2369391172c4SAl Viro unsigned int flags, struct path *parent, 2370391172c4SAl Viro struct qstr *last, int *type) 23718bcb77faSAl Viro { 23728bcb77faSAl Viro int retval; 23739883d185SAl Viro struct nameidata nd; 23748bcb77faSAl Viro 23755c31b6ceSAl Viro if (IS_ERR(name)) 23765c31b6ceSAl Viro return name; 23779883d185SAl Viro set_nameidata(&nd, dfd, name); 2378c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23798bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2380c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23818bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2382c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2383391172c4SAl Viro if (likely(!retval)) { 2384391172c4SAl Viro *last = nd.last; 2385391172c4SAl Viro *type = nd.last_type; 2386c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 23875c31b6ceSAl Viro } else { 23885c31b6ceSAl Viro putname(name); 23895c31b6ceSAl Viro name = ERR_PTR(retval); 2390391172c4SAl Viro } 23919883d185SAl Viro restore_nameidata(); 23925c31b6ceSAl Viro return name; 23938bcb77faSAl Viro } 23948bcb77faSAl Viro 239579714f72SAl Viro /* does lookup, returns the object with parent locked */ 239679714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23975590ff0dSUlrich Drepper { 23985c31b6ceSAl Viro struct filename *filename; 23995c31b6ceSAl Viro struct dentry *d; 2400391172c4SAl Viro struct qstr last; 2401391172c4SAl Viro int type; 240251689104SPaul Moore 24035c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24045c31b6ceSAl Viro &last, &type); 240551689104SPaul Moore if (IS_ERR(filename)) 240651689104SPaul Moore return ERR_CAST(filename); 24075c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2408391172c4SAl Viro path_put(path); 24095c31b6ceSAl Viro putname(filename); 24105c31b6ceSAl Viro return ERR_PTR(-EINVAL); 241179714f72SAl Viro } 24125955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2413391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 241479714f72SAl Viro if (IS_ERR(d)) { 24155955102cSAl Viro inode_unlock(path->dentry->d_inode); 2416391172c4SAl Viro path_put(path); 241779714f72SAl Viro } 241851689104SPaul Moore putname(filename); 241979714f72SAl Viro return d; 24205590ff0dSUlrich Drepper } 24215590ff0dSUlrich Drepper 2422d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2423d1811465SAl Viro { 2424abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2425abc9f5beSAl Viro flags, path, NULL); 2426d1811465SAl Viro } 24274d359507SAl Viro EXPORT_SYMBOL(kern_path); 2428d1811465SAl Viro 242916f18200SJosef 'Jeff' Sipek /** 243016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 243116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 243216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 243316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 243416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2435e0a01249SAl Viro * @path: pointer to struct path to fill 243616f18200SJosef 'Jeff' Sipek */ 243716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 243816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2439e0a01249SAl Viro struct path *path) 244016f18200SJosef 'Jeff' Sipek { 24419ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24429ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2443abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2444abc9f5beSAl Viro flags , path, &root); 244516f18200SJosef 'Jeff' Sipek } 24464d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 244716f18200SJosef 'Jeff' Sipek 24483c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24493c95f0dcSAl Viro int len, struct qstr *this) 24503c95f0dcSAl Viro { 24513c95f0dcSAl Viro this->name = name; 24523c95f0dcSAl Viro this->len = len; 24533c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24543c95f0dcSAl Viro if (!len) 24553c95f0dcSAl Viro return -EACCES; 24563c95f0dcSAl Viro 24573c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24583c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24593c95f0dcSAl Viro return -EACCES; 24603c95f0dcSAl Viro } 24613c95f0dcSAl Viro 24623c95f0dcSAl Viro while (len--) { 24633c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24643c95f0dcSAl Viro if (c == '/' || c == '\0') 24653c95f0dcSAl Viro return -EACCES; 24663c95f0dcSAl Viro } 24673c95f0dcSAl Viro /* 24683c95f0dcSAl Viro * See if the low-level filesystem might want 24693c95f0dcSAl Viro * to use its own hash.. 24703c95f0dcSAl Viro */ 24713c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24723c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24733c95f0dcSAl Viro if (err < 0) 24743c95f0dcSAl Viro return err; 24753c95f0dcSAl Viro } 24763c95f0dcSAl Viro 24773c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24783c95f0dcSAl Viro } 24793c95f0dcSAl Viro 2480eead1911SChristoph Hellwig /** 24810da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 24820da0b7fdSDavid Howells * @name: pathname component to lookup 24830da0b7fdSDavid Howells * @base: base directory to lookup from 24840da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 24850da0b7fdSDavid Howells * 24860da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 24870da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 24880da0b7fdSDavid Howells * 24890da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 24900da0b7fdSDavid Howells * not be called by generic code. 24910da0b7fdSDavid Howells * 24920da0b7fdSDavid Howells * The caller must hold base->i_mutex. 24930da0b7fdSDavid Howells */ 24940da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 24950da0b7fdSDavid Howells { 24960da0b7fdSDavid Howells struct qstr this; 24970da0b7fdSDavid Howells int err; 24980da0b7fdSDavid Howells 24990da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25000da0b7fdSDavid Howells 25010da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25020da0b7fdSDavid Howells if (err) 25030da0b7fdSDavid Howells return ERR_PTR(err); 25040da0b7fdSDavid Howells 25050da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25060da0b7fdSDavid Howells } 25070da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25080da0b7fdSDavid Howells 25090da0b7fdSDavid Howells /** 2510a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2511eead1911SChristoph Hellwig * @name: pathname component to lookup 2512eead1911SChristoph Hellwig * @base: base directory to lookup from 2513eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2514eead1911SChristoph Hellwig * 2515a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25169e7543e9SAl Viro * not be called by generic code. 2517bbddca8eSNeilBrown * 2518bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2519eead1911SChristoph Hellwig */ 2520057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2521057f6c01SJames Morris { 25228613a209SAl Viro struct dentry *dentry; 2523057f6c01SJames Morris struct qstr this; 2524cda309deSMiklos Szeredi int err; 2525057f6c01SJames Morris 25265955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25272f9092e1SDavid Woodhouse 25283c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2529cda309deSMiklos Szeredi if (err) 2530cda309deSMiklos Szeredi return ERR_PTR(err); 2531cda309deSMiklos Szeredi 25328613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25338613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2534057f6c01SJames Morris } 25354d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2536057f6c01SJames Morris 2537bbddca8eSNeilBrown /** 2538bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2539bbddca8eSNeilBrown * @name: pathname component to lookup 2540bbddca8eSNeilBrown * @base: base directory to lookup from 2541bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2542bbddca8eSNeilBrown * 2543bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2544bbddca8eSNeilBrown * not be called by generic code. 2545bbddca8eSNeilBrown * 2546bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2547bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2548bbddca8eSNeilBrown */ 2549bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2550bbddca8eSNeilBrown struct dentry *base, int len) 2551bbddca8eSNeilBrown { 2552bbddca8eSNeilBrown struct qstr this; 2553bbddca8eSNeilBrown int err; 255420d00ee8SLinus Torvalds struct dentry *ret; 2555bbddca8eSNeilBrown 25563c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2557bbddca8eSNeilBrown if (err) 2558bbddca8eSNeilBrown return ERR_PTR(err); 2559bbddca8eSNeilBrown 256020d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 256120d00ee8SLinus Torvalds if (!ret) 256220d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 256320d00ee8SLinus Torvalds return ret; 2564bbddca8eSNeilBrown } 2565bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2566bbddca8eSNeilBrown 2567eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2568eedf265aSEric W. Biederman int path_pts(struct path *path) 2569eedf265aSEric W. Biederman { 2570eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2571eedf265aSEric W. Biederman * the input path. 2572eedf265aSEric W. Biederman */ 2573eedf265aSEric W. Biederman struct dentry *child, *parent; 2574eedf265aSEric W. Biederman struct qstr this; 2575eedf265aSEric W. Biederman int ret; 2576eedf265aSEric W. Biederman 2577eedf265aSEric W. Biederman ret = path_parent_directory(path); 2578eedf265aSEric W. Biederman if (ret) 2579eedf265aSEric W. Biederman return ret; 2580eedf265aSEric W. Biederman 2581eedf265aSEric W. Biederman parent = path->dentry; 2582eedf265aSEric W. Biederman this.name = "pts"; 2583eedf265aSEric W. Biederman this.len = 3; 2584eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2585eedf265aSEric W. Biederman if (!child) 2586eedf265aSEric W. Biederman return -ENOENT; 2587eedf265aSEric W. Biederman 2588eedf265aSEric W. Biederman path->dentry = child; 2589eedf265aSEric W. Biederman dput(parent); 2590eedf265aSEric W. Biederman follow_mount(path); 2591eedf265aSEric W. Biederman return 0; 2592eedf265aSEric W. Biederman } 2593eedf265aSEric W. Biederman #endif 2594eedf265aSEric W. Biederman 25951fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25961fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25971da177e4SLinus Torvalds { 2598abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2599abc9f5beSAl Viro flags, path, NULL); 26001da177e4SLinus Torvalds } 2601b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26021fa1e7f6SAndy Whitcroft 26038033426eSJeff Layton /** 2604197df04cSAl Viro * mountpoint_last - look up last component for umount 26058033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 26068033426eSJeff Layton * 26078033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 26088033426eSJeff Layton * need to resolve the path without doing any revalidation. 26098033426eSJeff Layton * 26108033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 26118033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 26128033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 26138033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 26148033426eSJeff Layton * bogus and it doesn't exist. 26158033426eSJeff Layton * 26168033426eSJeff Layton * Returns: 26178033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2618ba8f4613SAl Viro * lookup found a negative dentry. 26198033426eSJeff Layton * 2620ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2621ba8f4613SAl Viro * symlink that needs to be followed. 26228033426eSJeff Layton * 26238033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2624ba8f4613SAl Viro * that needs to be followed. 26258033426eSJeff Layton */ 26268033426eSJeff Layton static int 2627ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 26288033426eSJeff Layton { 26298033426eSJeff Layton int error = 0; 26308033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2631ba8f4613SAl Viro struct path path; 26328033426eSJeff Layton 263335759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 263435759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26354675ac39SAl Viro if (unlazy_walk(nd)) 2636deb106c6SAl Viro return -ECHILD; 26378033426eSJeff Layton } 26388033426eSJeff Layton 26398033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26408033426eSJeff Layton 26418033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26428033426eSJeff Layton error = handle_dots(nd, nd->last_type); 264335759521SAl Viro if (error) 2644deb106c6SAl Viro return error; 2645ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2646949a852eSAl Viro } else { 2647ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2648ba8f4613SAl Viro if (!path.dentry) { 26498033426eSJeff Layton /* 2650949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2651949a852eSAl Viro * cache, so that means that this dentry is probably 2652949a852eSAl Viro * a symlink or the path doesn't actually point 2653949a852eSAl Viro * to a mounted dentry. 26548033426eSJeff Layton */ 2655ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2656949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2657ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2658ba8f4613SAl Viro return PTR_ERR(path.dentry); 26598033426eSJeff Layton } 2660bcceeebaSDave Jones } 2661ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2662ba8f4613SAl Viro dput(path.dentry); 2663deb106c6SAl Viro return -ENOENT; 266435759521SAl Viro } 2665ba8f4613SAl Viro path.mnt = nd->path.mnt; 26668f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26678033426eSJeff Layton } 26688033426eSJeff Layton 26698033426eSJeff Layton /** 2670197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26712a78b857SMasanari Iida * @nd: lookup context 26728033426eSJeff Layton * @flags: lookup flags 2673c8a53ee5SAl Viro * @path: pointer to container for result 26748033426eSJeff Layton * 26758033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2676606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26778033426eSJeff Layton */ 26788033426eSJeff Layton static int 2679c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26808033426eSJeff Layton { 2681c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2682368ee9baSAl Viro int err; 26839b5858e9SAl Viro 26843bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2685ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26863bdba28bSAl Viro s = trailing_symlink(nd); 26873bdba28bSAl Viro } 2688ba8f4613SAl Viro if (!err) { 2689ba8f4613SAl Viro *path = nd->path; 2690ba8f4613SAl Viro nd->path.mnt = NULL; 2691ba8f4613SAl Viro nd->path.dentry = NULL; 2692ba8f4613SAl Viro follow_mount(path); 2693ba8f4613SAl Viro } 2694deb106c6SAl Viro terminate_walk(nd); 26958033426eSJeff Layton return err; 26968033426eSJeff Layton } 26978033426eSJeff Layton 26982d864651SAl Viro static int 2699668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 27002d864651SAl Viro unsigned int flags) 27012d864651SAl Viro { 27029883d185SAl Viro struct nameidata nd; 2703cbaab2dbSAl Viro int error; 2704668696dcSAl Viro if (IS_ERR(name)) 2705668696dcSAl Viro return PTR_ERR(name); 27069883d185SAl Viro set_nameidata(&nd, dfd, name); 2707c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 27082d864651SAl Viro if (unlikely(error == -ECHILD)) 2709c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 27102d864651SAl Viro if (unlikely(error == -ESTALE)) 2711c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 27122d864651SAl Viro if (likely(!error)) 2713c9b07eabSAl Viro audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); 27149883d185SAl Viro restore_nameidata(); 2715668696dcSAl Viro putname(name); 27162d864651SAl Viro return error; 27172d864651SAl Viro } 27182d864651SAl Viro 27198033426eSJeff Layton /** 2720197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27218033426eSJeff Layton * @dfd: directory file descriptor 27228033426eSJeff Layton * @name: pathname from userland 27238033426eSJeff Layton * @flags: lookup flags 27248033426eSJeff Layton * @path: pointer to container to hold result 27258033426eSJeff Layton * 27268033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27278033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27288033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27298033426eSJeff Layton * and avoid revalidating the last component. 27308033426eSJeff Layton * 27318033426eSJeff Layton * Returns 0 and populates "path" on success. 27328033426eSJeff Layton */ 27338033426eSJeff Layton int 2734197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27358033426eSJeff Layton struct path *path) 27368033426eSJeff Layton { 2737cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27388033426eSJeff Layton } 27398033426eSJeff Layton 27402d864651SAl Viro int 27412d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27422d864651SAl Viro unsigned int flags) 27432d864651SAl Viro { 2744cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27452d864651SAl Viro } 27462d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27472d864651SAl Viro 2748cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27491da177e4SLinus Torvalds { 27508e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2751da9592edSDavid Howells 27528e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27531da177e4SLinus Torvalds return 0; 27548e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27551da177e4SLinus Torvalds return 0; 275623adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27571da177e4SLinus Torvalds } 2758cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27591da177e4SLinus Torvalds 27601da177e4SLinus Torvalds /* 27611da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27621da177e4SLinus Torvalds * whether the type of victim is right. 27631da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27641da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27651da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27661da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27671da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27681da177e4SLinus Torvalds * a. be owner of dir, or 27691da177e4SLinus Torvalds * b. be owner of victim, or 27701da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27711da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27721da177e4SLinus Torvalds * links pointing to it. 27730bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27740bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27750bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27760bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27770bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27781da177e4SLinus Torvalds * nfs_async_unlink(). 27791da177e4SLinus Torvalds */ 2780b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27811da177e4SLinus Torvalds { 278263afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27831da177e4SLinus Torvalds int error; 27841da177e4SLinus Torvalds 2785b18825a7SDavid Howells if (d_is_negative(victim)) 27861da177e4SLinus Torvalds return -ENOENT; 2787b18825a7SDavid Howells BUG_ON(!inode); 27881da177e4SLinus Torvalds 27891da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2790593d1ce8SEric W. Biederman 2791593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2792593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2793593d1ce8SEric W. Biederman return -EOVERFLOW; 2794593d1ce8SEric W. Biederman 27954fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27961da177e4SLinus Torvalds 2797f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27981da177e4SLinus Torvalds if (error) 27991da177e4SLinus Torvalds return error; 28001da177e4SLinus Torvalds if (IS_APPEND(dir)) 28011da177e4SLinus Torvalds return -EPERM; 2802b18825a7SDavid Howells 2803b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 28040bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 28051da177e4SLinus Torvalds return -EPERM; 28061da177e4SLinus Torvalds if (isdir) { 280744b1d530SMiklos Szeredi if (!d_is_dir(victim)) 28081da177e4SLinus Torvalds return -ENOTDIR; 28091da177e4SLinus Torvalds if (IS_ROOT(victim)) 28101da177e4SLinus Torvalds return -EBUSY; 281144b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 28121da177e4SLinus Torvalds return -EISDIR; 28131da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28141da177e4SLinus Torvalds return -ENOENT; 28151da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 28161da177e4SLinus Torvalds return -EBUSY; 28171da177e4SLinus Torvalds return 0; 28181da177e4SLinus Torvalds } 28191da177e4SLinus Torvalds 28201da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28211da177e4SLinus Torvalds * dir. 28221da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28231da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28241da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2825036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2826036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2827036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 28281da177e4SLinus Torvalds */ 2829a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28301da177e4SLinus Torvalds { 2831036d5236SEric W. Biederman struct user_namespace *s_user_ns; 283214e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28331da177e4SLinus Torvalds if (child->d_inode) 28341da177e4SLinus Torvalds return -EEXIST; 28351da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28361da177e4SLinus Torvalds return -ENOENT; 2837036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2838036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2839036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2840036d5236SEric W. Biederman return -EOVERFLOW; 2841f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28421da177e4SLinus Torvalds } 28431da177e4SLinus Torvalds 28441da177e4SLinus Torvalds /* 28451da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28461da177e4SLinus Torvalds */ 28471da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28481da177e4SLinus Torvalds { 28491da177e4SLinus Torvalds struct dentry *p; 28501da177e4SLinus Torvalds 28511da177e4SLinus Torvalds if (p1 == p2) { 28525955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28531da177e4SLinus Torvalds return NULL; 28541da177e4SLinus Torvalds } 28551da177e4SLinus Torvalds 2856fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28571da177e4SLinus Torvalds 2858e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2859e2761a11SOGAWA Hirofumi if (p) { 28605955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28615955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28621da177e4SLinus Torvalds return p; 28631da177e4SLinus Torvalds } 28641da177e4SLinus Torvalds 2865e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2866e2761a11SOGAWA Hirofumi if (p) { 28675955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28685955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28691da177e4SLinus Torvalds return p; 28701da177e4SLinus Torvalds } 28711da177e4SLinus Torvalds 28725955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28735955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28741da177e4SLinus Torvalds return NULL; 28751da177e4SLinus Torvalds } 28764d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28771da177e4SLinus Torvalds 28781da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28791da177e4SLinus Torvalds { 28805955102cSAl Viro inode_unlock(p1->d_inode); 28811da177e4SLinus Torvalds if (p1 != p2) { 28825955102cSAl Viro inode_unlock(p2->d_inode); 2883fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28841da177e4SLinus Torvalds } 28851da177e4SLinus Torvalds } 28864d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28871da177e4SLinus Torvalds 28884acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2889312b63fbSAl Viro bool want_excl) 28901da177e4SLinus Torvalds { 2891a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28921da177e4SLinus Torvalds if (error) 28931da177e4SLinus Torvalds return error; 28941da177e4SLinus Torvalds 2895acfa4380SAl Viro if (!dir->i_op->create) 28961da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28971da177e4SLinus Torvalds mode &= S_IALLUGO; 28981da177e4SLinus Torvalds mode |= S_IFREG; 28991da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 29001da177e4SLinus Torvalds if (error) 29011da177e4SLinus Torvalds return error; 2902312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2903a74574aaSStephen Smalley if (!error) 2904f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29051da177e4SLinus Torvalds return error; 29061da177e4SLinus Torvalds } 29074d359507SAl Viro EXPORT_SYMBOL(vfs_create); 29081da177e4SLinus Torvalds 29098e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 29108e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 29118e6c848eSAl Viro void *arg) 29128e6c848eSAl Viro { 29138e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 29148e6c848eSAl Viro int error = may_create(dir, dentry); 29158e6c848eSAl Viro if (error) 29168e6c848eSAl Viro return error; 29178e6c848eSAl Viro 29188e6c848eSAl Viro mode &= S_IALLUGO; 29198e6c848eSAl Viro mode |= S_IFREG; 29208e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 29218e6c848eSAl Viro if (error) 29228e6c848eSAl Viro return error; 29238e6c848eSAl Viro error = f(dentry, mode, arg); 29248e6c848eSAl Viro if (!error) 29258e6c848eSAl Viro fsnotify_create(dir, dentry); 29268e6c848eSAl Viro return error; 29278e6c848eSAl Viro } 29288e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 29298e6c848eSAl Viro 2930a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2931a2982cc9SEric W. Biederman { 2932a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2933a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2934a2982cc9SEric W. Biederman } 2935a2982cc9SEric W. Biederman 2936f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 29371da177e4SLinus Torvalds { 29383fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29391da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29401da177e4SLinus Torvalds int error; 29411da177e4SLinus Torvalds 29421da177e4SLinus Torvalds if (!inode) 29431da177e4SLinus Torvalds return -ENOENT; 29441da177e4SLinus Torvalds 2945c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2946c8fe8f30SChristoph Hellwig case S_IFLNK: 29471da177e4SLinus Torvalds return -ELOOP; 2948c8fe8f30SChristoph Hellwig case S_IFDIR: 2949c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29501da177e4SLinus Torvalds return -EISDIR; 2951c8fe8f30SChristoph Hellwig break; 2952c8fe8f30SChristoph Hellwig case S_IFBLK: 2953c8fe8f30SChristoph Hellwig case S_IFCHR: 2954a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29551da177e4SLinus Torvalds return -EACCES; 2956c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2957c8fe8f30SChristoph Hellwig case S_IFIFO: 2958c8fe8f30SChristoph Hellwig case S_IFSOCK: 29591da177e4SLinus Torvalds flag &= ~O_TRUNC; 2960c8fe8f30SChristoph Hellwig break; 29614a3fd211SDave Hansen } 2962b41572e9SDave Hansen 296362fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2964b41572e9SDave Hansen if (error) 2965b41572e9SDave Hansen return error; 29666146f0d5SMimi Zohar 29671da177e4SLinus Torvalds /* 29681da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29691da177e4SLinus Torvalds */ 29701da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29718737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29727715b521SAl Viro return -EPERM; 29731da177e4SLinus Torvalds if (flag & O_TRUNC) 29747715b521SAl Viro return -EPERM; 29751da177e4SLinus Torvalds } 29761da177e4SLinus Torvalds 29771da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29782e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29797715b521SAl Viro return -EPERM; 29801da177e4SLinus Torvalds 2981f3c7691eSJ. Bruce Fields return 0; 29827715b521SAl Viro } 29837715b521SAl Viro 2984e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29857715b521SAl Viro { 2986f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29877715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29887715b521SAl Viro int error = get_write_access(inode); 29891da177e4SLinus Torvalds if (error) 29907715b521SAl Viro return error; 29911da177e4SLinus Torvalds /* 29921da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29931da177e4SLinus Torvalds */ 2994d7a06983SJeff Layton error = locks_verify_locked(filp); 2995be6d3e56SKentaro Takeda if (!error) 2996ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29971da177e4SLinus Torvalds if (!error) { 29987715b521SAl Viro error = do_truncate(path->dentry, 0, 2999d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 3000e1181ee6SJeff Layton filp); 30011da177e4SLinus Torvalds } 30021da177e4SLinus Torvalds put_write_access(inode); 3003acd0c935SMimi Zohar return error; 30041da177e4SLinus Torvalds } 30051da177e4SLinus Torvalds 3006d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 3007d57999e1SDave Hansen { 30088a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 30098a5e929dSAl Viro flag--; 3010d57999e1SDave Hansen return flag; 3011d57999e1SDave Hansen } 3012d57999e1SDave Hansen 3013d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 3014d18e9008SMiklos Szeredi { 30151328c727SSeth Forshee struct user_namespace *s_user_ns; 3016d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 3017d18e9008SMiklos Szeredi if (error) 3018d18e9008SMiklos Szeredi return error; 3019d18e9008SMiklos Szeredi 30201328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 30211328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 30221328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 30231328c727SSeth Forshee return -EOVERFLOW; 30241328c727SSeth Forshee 3025d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 3026d18e9008SMiklos Szeredi if (error) 3027d18e9008SMiklos Szeredi return error; 3028d18e9008SMiklos Szeredi 3029d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 3030d18e9008SMiklos Szeredi } 3031d18e9008SMiklos Szeredi 30321acf0af9SDavid Howells /* 30331acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 30341acf0af9SDavid Howells * dentry. 30351acf0af9SDavid Howells * 30361acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 30371acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 30381acf0af9SDavid Howells * 303900a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 304000a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 304100a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 30421acf0af9SDavid Howells * 30431acf0af9SDavid Howells * Returns an error code otherwise. 30441acf0af9SDavid Howells */ 30452675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 304630d90494SAl Viro struct path *path, struct file *file, 3047015c3bbcSMiklos Szeredi const struct open_flags *op, 30483ec2eef1SAl Viro int open_flag, umode_t mode) 3049d18e9008SMiklos Szeredi { 3050d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3051d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3052d18e9008SMiklos Szeredi int error; 3053d18e9008SMiklos Szeredi 3054384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3055d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3056d18e9008SMiklos Szeredi 3057d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3058d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3059d18e9008SMiklos Szeredi 306030d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 306130d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30620fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 306344907d79SAl Viro open_to_namei_flags(open_flag), mode); 30646fbd0714SAl Viro d_lookup_done(dentry); 3065384f26e2SAl Viro if (!error) { 306664e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3067d18e9008SMiklos Szeredi /* 3068384f26e2SAl Viro * We didn't have the inode before the open, so check open 3069384f26e2SAl Viro * permission here. 3070d18e9008SMiklos Szeredi */ 3071384f26e2SAl Viro int acc_mode = op->acc_mode; 307273a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 307303da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 307403da633aSAl Viro fsnotify_create(dir, dentry); 307562fb4a15SAl Viro acc_mode = 0; 307603da633aSAl Viro } 30772675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3078384f26e2SAl Viro if (WARN_ON(error > 0)) 3079384f26e2SAl Viro error = -EINVAL; 308064e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3081d18e9008SMiklos Szeredi error = -EIO; 3082384f26e2SAl Viro } else { 3083d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3084d18e9008SMiklos Szeredi dput(dentry); 3085d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 308610c64ceaSAl Viro } 308773a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3088d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3089a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3090a01e718fSAl Viro error = -ENOENT; 3091a01e718fSAl Viro } else { 3092d18e9008SMiklos Szeredi path->dentry = dentry; 3093d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 309400a07c15SAl Viro return 0; 3095d18e9008SMiklos Szeredi } 3096d18e9008SMiklos Szeredi } 3097a01e718fSAl Viro } 3098d18e9008SMiklos Szeredi dput(dentry); 3099d18e9008SMiklos Szeredi return error; 3100d18e9008SMiklos Szeredi } 3101d18e9008SMiklos Szeredi 310231e6b01fSNick Piggin /* 31031acf0af9SDavid Howells * Look up and maybe create and open the last component. 3104d58ffd35SMiklos Szeredi * 310500a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3106d58ffd35SMiklos Szeredi * 310700a07c15SAl Viro * Returns 0 on success, that is, if 310800a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 310900a07c15SAl Viro * the file was not completely opened at this time, though lookups and 311000a07c15SAl Viro * creations were performed. 311100a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 311200a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 311300a07c15SAl Viro * hadn't been specified. 31141acf0af9SDavid Howells * 311500a07c15SAl Viro * An error code is returned on failure. 3116d58ffd35SMiklos Szeredi */ 31172675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 311830d90494SAl Viro struct file *file, 3119d58ffd35SMiklos Szeredi const struct open_flags *op, 31203ec2eef1SAl Viro bool got_write) 3121d58ffd35SMiklos Szeredi { 3122d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 312354ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 31241643b43fSAl Viro int open_flag = op->open_flag; 3125d58ffd35SMiklos Szeredi struct dentry *dentry; 31261643b43fSAl Viro int error, create_error = 0; 31271643b43fSAl Viro umode_t mode = op->mode; 31286fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3129d58ffd35SMiklos Szeredi 3130ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3131ce8644fcSAl Viro return -ENOENT; 3132d58ffd35SMiklos Szeredi 313373a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 31346fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 31356fbd0714SAl Viro for (;;) { 31366fbd0714SAl Viro if (!dentry) { 31376fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3138d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31392675a4ebSAl Viro return PTR_ERR(dentry); 31406fbd0714SAl Viro } 31416fbd0714SAl Viro if (d_in_lookup(dentry)) 31426fbd0714SAl Viro break; 3143d58ffd35SMiklos Szeredi 31446fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31456fbd0714SAl Viro if (likely(error > 0)) 31466fbd0714SAl Viro break; 31476fbd0714SAl Viro if (error) 31486fbd0714SAl Viro goto out_dput; 31496fbd0714SAl Viro d_invalidate(dentry); 31506fbd0714SAl Viro dput(dentry); 31516fbd0714SAl Viro dentry = NULL; 31526fbd0714SAl Viro } 31536fbd0714SAl Viro if (dentry->d_inode) { 3154d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3155d18e9008SMiklos Szeredi goto out_no_open; 31566c51e513SAl Viro } 3157d18e9008SMiklos Szeredi 31581643b43fSAl Viro /* 31591643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31601643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31611643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31621643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31631643b43fSAl Viro * 31641643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31651643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31661643b43fSAl Viro */ 31671643b43fSAl Viro if (open_flag & O_CREAT) { 31681643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31691643b43fSAl Viro mode &= ~current_umask(); 31701643b43fSAl Viro if (unlikely(!got_write)) { 31711643b43fSAl Viro create_error = -EROFS; 31721643b43fSAl Viro open_flag &= ~O_CREAT; 31731643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31741643b43fSAl Viro goto no_open; 31751643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31761643b43fSAl Viro } else { 31771643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31781643b43fSAl Viro if (create_error) { 31791643b43fSAl Viro open_flag &= ~O_CREAT; 31801643b43fSAl Viro if (open_flag & O_EXCL) 31811643b43fSAl Viro goto no_open; 31821643b43fSAl Viro } 31831643b43fSAl Viro } 31841643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31851643b43fSAl Viro unlikely(!got_write)) { 31861643b43fSAl Viro /* 31871643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31881643b43fSAl Viro * back to lookup + open 31891643b43fSAl Viro */ 31901643b43fSAl Viro goto no_open; 3191d18e9008SMiklos Szeredi } 3192d18e9008SMiklos Szeredi 31931643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31941643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31953ec2eef1SAl Viro mode); 31961643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31971643b43fSAl Viro error = create_error; 31981643b43fSAl Viro return error; 31991643b43fSAl Viro } 320054ef4872SMiklos Szeredi 32011643b43fSAl Viro no_open: 32026fbd0714SAl Viro if (d_in_lookup(dentry)) { 320312fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 320412fa5e24SAl Viro nd->flags); 32056fbd0714SAl Viro d_lookup_done(dentry); 320612fa5e24SAl Viro if (unlikely(res)) { 320712fa5e24SAl Viro if (IS_ERR(res)) { 320812fa5e24SAl Viro error = PTR_ERR(res); 320912fa5e24SAl Viro goto out_dput; 321012fa5e24SAl Viro } 321112fa5e24SAl Viro dput(dentry); 321212fa5e24SAl Viro dentry = res; 321312fa5e24SAl Viro } 321454ef4872SMiklos Szeredi } 321554ef4872SMiklos Szeredi 3216d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 32171643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 321873a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3219ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3220ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3221ce8644fcSAl Viro error = -EACCES; 3222d58ffd35SMiklos Szeredi goto out_dput; 322364894cf8SAl Viro } 3224ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 32251643b43fSAl Viro open_flag & O_EXCL); 3226d58ffd35SMiklos Szeredi if (error) 3227d58ffd35SMiklos Szeredi goto out_dput; 3228ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3229d58ffd35SMiklos Szeredi } 32301643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 32311643b43fSAl Viro error = create_error; 3232d58ffd35SMiklos Szeredi goto out_dput; 3233d58ffd35SMiklos Szeredi } 3234d18e9008SMiklos Szeredi out_no_open: 3235d58ffd35SMiklos Szeredi path->dentry = dentry; 3236d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 323700a07c15SAl Viro return 0; 3238d58ffd35SMiklos Szeredi 3239d58ffd35SMiklos Szeredi out_dput: 3240d58ffd35SMiklos Szeredi dput(dentry); 32412675a4ebSAl Viro return error; 3242d58ffd35SMiklos Szeredi } 3243d58ffd35SMiklos Szeredi 3244d58ffd35SMiklos Szeredi /* 3245fe2d35ffSAl Viro * Handle the last step of open() 324631e6b01fSNick Piggin */ 3247896475d5SAl Viro static int do_last(struct nameidata *nd, 32483ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3249fb1cc555SAl Viro { 3250a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3251ca344a89SAl Viro int open_flag = op->open_flag; 325277d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 325364894cf8SAl Viro bool got_write = false; 3254bcda7652SAl Viro int acc_mode = op->acc_mode; 3255254cf582SAl Viro unsigned seq; 3256a1eb3315SMiklos Szeredi struct inode *inode; 3257896475d5SAl Viro struct path path; 325816c2cd71SAl Viro int error; 3259fb1cc555SAl Viro 3260c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3261c3e380b0SAl Viro nd->flags |= op->intent; 3262c3e380b0SAl Viro 3263bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3264fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3265deb106c6SAl Viro if (unlikely(error)) 32662675a4ebSAl Viro return error; 3267e83db167SMiklos Szeredi goto finish_open; 32681f36f774SAl Viro } 3269a2c36b45SAl Viro 3270ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3271fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3272fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3273fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3274254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3275e9742b53SAl Viro if (likely(error > 0)) 327671574865SMiklos Szeredi goto finish_lookup; 327771574865SMiklos Szeredi 3278ce57dfc1SAl Viro if (error < 0) 3279deb106c6SAl Viro return error; 3280a1eb3315SMiklos Szeredi 328137d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32826583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3283b6183df7SMiklos Szeredi } else { 3284fe2d35ffSAl Viro /* create side of things */ 3285a3fbbde7SAl Viro /* 3286b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3287b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3288b6183df7SMiklos Szeredi * about to look up 3289a3fbbde7SAl Viro */ 32909f1fafeeSAl Viro error = complete_walk(nd); 3291e8bb73dfSAl Viro if (error) 32922675a4ebSAl Viro return error; 3293fe2d35ffSAl Viro 3294c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32951f36f774SAl Viro /* trailing slashes? */ 3296deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3297deb106c6SAl Viro return -EISDIR; 3298b6183df7SMiklos Szeredi } 32991f36f774SAl Viro 33009cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 330164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 330264894cf8SAl Viro if (!error) 330364894cf8SAl Viro got_write = true; 330464894cf8SAl Viro /* 330564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 330664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 330764894cf8SAl Viro * dropping this one anyway. 330864894cf8SAl Viro */ 330964894cf8SAl Viro } 33109cf843e3SAl Viro if (open_flag & O_CREAT) 33115955102cSAl Viro inode_lock(dir->d_inode); 33129cf843e3SAl Viro else 33139cf843e3SAl Viro inode_lock_shared(dir->d_inode); 33143ec2eef1SAl Viro error = lookup_open(nd, &path, file, op, got_write); 33159cf843e3SAl Viro if (open_flag & O_CREAT) 33165955102cSAl Viro inode_unlock(dir->d_inode); 33179cf843e3SAl Viro else 33189cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3319fb1cc555SAl Viro 33202675a4ebSAl Viro if (error) 3321d58ffd35SMiklos Szeredi goto out; 33226c0d46c4SAl Viro 332300a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 332473a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3325496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 332677d660a8SMiklos Szeredi will_truncate = false; 3327d18e9008SMiklos Szeredi 332876ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3329d18e9008SMiklos Szeredi goto opened; 3330d18e9008SMiklos Szeredi } 3331d18e9008SMiklos Szeredi 333273a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 33339b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3334ca344a89SAl Viro open_flag &= ~O_TRUNC; 333577d660a8SMiklos Szeredi will_truncate = false; 333662fb4a15SAl Viro acc_mode = 0; 3337896475d5SAl Viro path_to_nameidata(&path, nd); 3338e83db167SMiklos Szeredi goto finish_open_created; 3339fb1cc555SAl Viro } 3340fb1cc555SAl Viro 3341fb1cc555SAl Viro /* 3342d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3343d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3344d18e9008SMiklos Szeredi * necessary...) 3345d18e9008SMiklos Szeredi */ 334664894cf8SAl Viro if (got_write) { 3347d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 334864894cf8SAl Viro got_write = false; 3349d18e9008SMiklos Szeredi } 3350d18e9008SMiklos Szeredi 3351e6ec03a2SAl Viro error = follow_managed(&path, nd); 3352e6ec03a2SAl Viro if (unlikely(error < 0)) 3353e6ec03a2SAl Viro return error; 3354e6ec03a2SAl Viro 33556583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33566583fe22SAl Viro path_to_nameidata(&path, nd); 33576583fe22SAl Viro return -ENOENT; 33586583fe22SAl Viro } 33596583fe22SAl Viro 33606583fe22SAl Viro /* 33616583fe22SAl Viro * create/update audit record if it already exists. 33626583fe22SAl Viro */ 33636583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33646583fe22SAl Viro 3365deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3366deb106c6SAl Viro path_to_nameidata(&path, nd); 3367deb106c6SAl Viro return -EEXIST; 3368deb106c6SAl Viro } 3369fb1cc555SAl Viro 3370254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3371d4565649SAl Viro inode = d_backing_inode(path.dentry); 3372766c4cbfSAl Viro finish_lookup: 33738f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3374deb106c6SAl Viro if (unlikely(error)) 3375d63ff28fSAl Viro return error; 3376bc77daa7SAl Viro finish_open: 33778f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3378a3fbbde7SAl Viro error = complete_walk(nd); 3379fac7d191SAl Viro if (error) 33802675a4ebSAl Viro return error; 338176ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 338230aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3383fb1cc555SAl Viro error = -EISDIR; 338430aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 33852675a4ebSAl Viro goto out; 338630aba665SSalvatore Mesoraca error = may_create_in_sticky(dir, 338730aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 338830aba665SSalvatore Mesoraca if (unlikely(error)) 338930aba665SSalvatore Mesoraca goto out; 339030aba665SSalvatore Mesoraca } 3391af2f5542SMiklos Szeredi error = -ENOTDIR; 339244b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33932675a4ebSAl Viro goto out; 33944bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 339577d660a8SMiklos Szeredi will_truncate = false; 33966c0d46c4SAl Viro 33970f9d1a10SAl Viro if (will_truncate) { 33980f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33990f9d1a10SAl Viro if (error) 34002675a4ebSAl Viro goto out; 340164894cf8SAl Viro got_write = true; 34020f9d1a10SAl Viro } 3403e83db167SMiklos Szeredi finish_open_created: 3404bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3405ca344a89SAl Viro if (error) 34062675a4ebSAl Viro goto out; 3407aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3408ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3409fac7d191SAl Viro if (error) 3410015c3bbcSMiklos Szeredi goto out; 3411a8277b9bSMiklos Szeredi opened: 34126035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3413fe9ec829SAl Viro if (!error && will_truncate) 34142675a4ebSAl Viro error = handle_truncate(file); 3415ca344a89SAl Viro out: 3416c80567c8SAl Viro if (unlikely(error > 0)) { 3417c80567c8SAl Viro WARN_ON(1); 3418c80567c8SAl Viro error = -EINVAL; 3419c80567c8SAl Viro } 342064894cf8SAl Viro if (got_write) 34210f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 34222675a4ebSAl Viro return error; 3423fb1cc555SAl Viro } 3424fb1cc555SAl Viro 3425af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3426af7bd4dcSAmir Goldstein { 3427af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3428af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3429af7bd4dcSAmir Goldstein struct inode *inode; 3430af7bd4dcSAmir Goldstein int error; 3431af7bd4dcSAmir Goldstein 3432af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3433af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3434af7bd4dcSAmir Goldstein if (error) 3435af7bd4dcSAmir Goldstein goto out_err; 3436af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3437af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3438af7bd4dcSAmir Goldstein goto out_err; 3439af7bd4dcSAmir Goldstein error = -ENOMEM; 3440cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3441af7bd4dcSAmir Goldstein if (unlikely(!child)) 3442af7bd4dcSAmir Goldstein goto out_err; 3443af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3444af7bd4dcSAmir Goldstein if (error) 3445af7bd4dcSAmir Goldstein goto out_err; 3446af7bd4dcSAmir Goldstein error = -ENOENT; 3447af7bd4dcSAmir Goldstein inode = child->d_inode; 3448af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3449af7bd4dcSAmir Goldstein goto out_err; 3450af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3451af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3452af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3453af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3454af7bd4dcSAmir Goldstein } 3455fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3456af7bd4dcSAmir Goldstein return child; 3457af7bd4dcSAmir Goldstein 3458af7bd4dcSAmir Goldstein out_err: 3459af7bd4dcSAmir Goldstein dput(child); 3460af7bd4dcSAmir Goldstein return ERR_PTR(error); 3461af7bd4dcSAmir Goldstein } 3462af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3463af7bd4dcSAmir Goldstein 3464c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 346560545d0dSAl Viro const struct open_flags *op, 34663ec2eef1SAl Viro struct file *file) 346760545d0dSAl Viro { 3468625b6d10SAl Viro struct dentry *child; 3469625b6d10SAl Viro struct path path; 3470c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 347160545d0dSAl Viro if (unlikely(error)) 347260545d0dSAl Viro return error; 3473625b6d10SAl Viro error = mnt_want_write(path.mnt); 347460545d0dSAl Viro if (unlikely(error)) 347560545d0dSAl Viro goto out; 3476af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3477af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3478684e73beSHirofumi Nakagawa if (IS_ERR(child)) 347960545d0dSAl Viro goto out2; 3480625b6d10SAl Viro dput(path.dentry); 3481625b6d10SAl Viro path.dentry = child; 3482c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 348369a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 348462fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 348560545d0dSAl Viro if (error) 348660545d0dSAl Viro goto out2; 3487625b6d10SAl Viro file->f_path.mnt = path.mnt; 3488be12af3eSAl Viro error = finish_open(file, child, NULL); 348960545d0dSAl Viro out2: 3490625b6d10SAl Viro mnt_drop_write(path.mnt); 349160545d0dSAl Viro out: 3492625b6d10SAl Viro path_put(&path); 349360545d0dSAl Viro return error; 349460545d0dSAl Viro } 349560545d0dSAl Viro 34966ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34976ac08709SAl Viro { 34986ac08709SAl Viro struct path path; 34996ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 35006ac08709SAl Viro if (!error) { 35016ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3502ae2bb293SAl Viro error = vfs_open(&path, file); 35036ac08709SAl Viro path_put(&path); 35046ac08709SAl Viro } 35056ac08709SAl Viro return error; 35066ac08709SAl Viro } 35076ac08709SAl Viro 3508c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3509c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 35101da177e4SLinus Torvalds { 351130d90494SAl Viro struct file *file; 351213aab428SAl Viro int error; 351331e6b01fSNick Piggin 3514ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 35151afc99beSAl Viro if (IS_ERR(file)) 35161afc99beSAl Viro return file; 351731e6b01fSNick Piggin 3518bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 35193ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 35205f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 35216ac08709SAl Viro error = do_o_path(nd, flags, file); 35225f336e72SAl Viro } else { 35235f336e72SAl Viro const char *s = path_init(nd, flags); 35243bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 35253ec2eef1SAl Viro (error = do_last(nd, file, op)) > 0) { 352673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35273bdba28bSAl Viro s = trailing_symlink(nd); 35283bdba28bSAl Viro } 3529deb106c6SAl Viro terminate_walk(nd); 35305f336e72SAl Viro } 35317c1c01ecSAl Viro if (likely(!error)) { 3532aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 35337c1c01ecSAl Viro return file; 35347c1c01ecSAl Viro WARN_ON(1); 35357c1c01ecSAl Viro error = -EINVAL; 3536015c3bbcSMiklos Szeredi } 35377c1c01ecSAl Viro fput(file); 35382675a4ebSAl Viro if (error == -EOPENSTALE) { 35392675a4ebSAl Viro if (flags & LOOKUP_RCU) 35402675a4ebSAl Viro error = -ECHILD; 35412675a4ebSAl Viro else 35422675a4ebSAl Viro error = -ESTALE; 35432675a4ebSAl Viro } 35447c1c01ecSAl Viro return ERR_PTR(error); 3545de459215SKirill Korotaev } 35461da177e4SLinus Torvalds 3547669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3548f9652e10SAl Viro const struct open_flags *op) 354913aab428SAl Viro { 35509883d185SAl Viro struct nameidata nd; 3551f9652e10SAl Viro int flags = op->lookup_flags; 355213aab428SAl Viro struct file *filp; 355313aab428SAl Viro 35549883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3555c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 355613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3557c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 355813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3559c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35609883d185SAl Viro restore_nameidata(); 356113aab428SAl Viro return filp; 356213aab428SAl Viro } 356313aab428SAl Viro 356473d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3565f9652e10SAl Viro const char *name, const struct open_flags *op) 356673d049a4SAl Viro { 35679883d185SAl Viro struct nameidata nd; 356873d049a4SAl Viro struct file *file; 356951689104SPaul Moore struct filename *filename; 3570f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 357173d049a4SAl Viro 357273d049a4SAl Viro nd.root.mnt = mnt; 357373d049a4SAl Viro nd.root.dentry = dentry; 357473d049a4SAl Viro 3575b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 357673d049a4SAl Viro return ERR_PTR(-ELOOP); 357773d049a4SAl Viro 357851689104SPaul Moore filename = getname_kernel(name); 3579a1c83681SViresh Kumar if (IS_ERR(filename)) 358051689104SPaul Moore return ERR_CAST(filename); 358151689104SPaul Moore 35829883d185SAl Viro set_nameidata(&nd, -1, filename); 3583c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 358473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3585c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 358673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3587c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35889883d185SAl Viro restore_nameidata(); 358951689104SPaul Moore putname(filename); 359073d049a4SAl Viro return file; 359173d049a4SAl Viro } 359273d049a4SAl Viro 3593fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35941ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35951da177e4SLinus Torvalds { 3596c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3597391172c4SAl Viro struct qstr last; 3598391172c4SAl Viro int type; 3599c30dabfeSJan Kara int err2; 36001ac12b4bSJeff Layton int error; 36011ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 36021ac12b4bSJeff Layton 36031ac12b4bSJeff Layton /* 36041ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 36051ac12b4bSJeff Layton * other flags passed in are ignored! 36061ac12b4bSJeff Layton */ 36071ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 36081ac12b4bSJeff Layton 36095c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36105c31b6ceSAl Viro if (IS_ERR(name)) 36115c31b6ceSAl Viro return ERR_CAST(name); 36121da177e4SLinus Torvalds 3613c663e5d8SChristoph Hellwig /* 3614c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3615c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3616c663e5d8SChristoph Hellwig */ 36175c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3618ed75e95dSAl Viro goto out; 3619c663e5d8SChristoph Hellwig 3620c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3621391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3622c663e5d8SChristoph Hellwig /* 3623c663e5d8SChristoph Hellwig * Do the final lookup. 3624c663e5d8SChristoph Hellwig */ 3625391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36265955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3627391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36281da177e4SLinus Torvalds if (IS_ERR(dentry)) 3629a8104a9fSAl Viro goto unlock; 3630c663e5d8SChristoph Hellwig 3631a8104a9fSAl Viro error = -EEXIST; 3632b18825a7SDavid Howells if (d_is_positive(dentry)) 3633a8104a9fSAl Viro goto fail; 3634b18825a7SDavid Howells 3635c663e5d8SChristoph Hellwig /* 3636c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3637c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3638c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3639c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3640c663e5d8SChristoph Hellwig */ 3641391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3642a8104a9fSAl Viro error = -ENOENT; 3643ed75e95dSAl Viro goto fail; 3644e9baf6e5SAl Viro } 3645c30dabfeSJan Kara if (unlikely(err2)) { 3646c30dabfeSJan Kara error = err2; 3647a8104a9fSAl Viro goto fail; 3648c30dabfeSJan Kara } 3649181c37b6SAl Viro putname(name); 3650e9baf6e5SAl Viro return dentry; 36511da177e4SLinus Torvalds fail: 3652a8104a9fSAl Viro dput(dentry); 3653a8104a9fSAl Viro dentry = ERR_PTR(error); 3654a8104a9fSAl Viro unlock: 36555955102cSAl Viro inode_unlock(path->dentry->d_inode); 3656c30dabfeSJan Kara if (!err2) 3657391172c4SAl Viro mnt_drop_write(path->mnt); 3658ed75e95dSAl Viro out: 3659391172c4SAl Viro path_put(path); 3660181c37b6SAl Viro putname(name); 3661ed75e95dSAl Viro return dentry; 3662dae6ad8fSAl Viro } 3663fa14a0b8SAl Viro 3664fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3665fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3666fa14a0b8SAl Viro { 3667181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3668181c37b6SAl Viro path, lookup_flags); 3669fa14a0b8SAl Viro } 3670dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3671dae6ad8fSAl Viro 3672921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3673921a1650SAl Viro { 3674921a1650SAl Viro dput(dentry); 36755955102cSAl Viro inode_unlock(path->dentry->d_inode); 3676a8104a9fSAl Viro mnt_drop_write(path->mnt); 3677921a1650SAl Viro path_put(path); 3678921a1650SAl Viro } 3679921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3680921a1650SAl Viro 3681520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36821ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3683dae6ad8fSAl Viro { 3684181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3685dae6ad8fSAl Viro } 3686dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3687dae6ad8fSAl Viro 36881a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36891da177e4SLinus Torvalds { 3690a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36911da177e4SLinus Torvalds 36921da177e4SLinus Torvalds if (error) 36931da177e4SLinus Torvalds return error; 36941da177e4SLinus Torvalds 369594f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36961da177e4SLinus Torvalds return -EPERM; 36971da177e4SLinus Torvalds 3698acfa4380SAl Viro if (!dir->i_op->mknod) 36991da177e4SLinus Torvalds return -EPERM; 37001da177e4SLinus Torvalds 370108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 370208ce5f16SSerge E. Hallyn if (error) 370308ce5f16SSerge E. Hallyn return error; 370408ce5f16SSerge E. Hallyn 37051da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 37061da177e4SLinus Torvalds if (error) 37071da177e4SLinus Torvalds return error; 37081da177e4SLinus Torvalds 37091da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3710a74574aaSStephen Smalley if (!error) 3711f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37121da177e4SLinus Torvalds return error; 37131da177e4SLinus Torvalds } 37144d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37151da177e4SLinus Torvalds 3716f69aac00SAl Viro static int may_mknod(umode_t mode) 3717463c3197SDave Hansen { 3718463c3197SDave Hansen switch (mode & S_IFMT) { 3719463c3197SDave Hansen case S_IFREG: 3720463c3197SDave Hansen case S_IFCHR: 3721463c3197SDave Hansen case S_IFBLK: 3722463c3197SDave Hansen case S_IFIFO: 3723463c3197SDave Hansen case S_IFSOCK: 3724463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3725463c3197SDave Hansen return 0; 3726463c3197SDave Hansen case S_IFDIR: 3727463c3197SDave Hansen return -EPERM; 3728463c3197SDave Hansen default: 3729463c3197SDave Hansen return -EINVAL; 3730463c3197SDave Hansen } 3731463c3197SDave Hansen } 3732463c3197SDave Hansen 373387c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 373487c4e192SDominik Brodowski unsigned int dev) 37351da177e4SLinus Torvalds { 37361da177e4SLinus Torvalds struct dentry *dentry; 3737dae6ad8fSAl Viro struct path path; 3738dae6ad8fSAl Viro int error; 3739972567f1SJeff Layton unsigned int lookup_flags = 0; 37401da177e4SLinus Torvalds 37418e4bfca1SAl Viro error = may_mknod(mode); 37428e4bfca1SAl Viro if (error) 37438e4bfca1SAl Viro return error; 3744972567f1SJeff Layton retry: 3745972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3746dae6ad8fSAl Viro if (IS_ERR(dentry)) 3747dae6ad8fSAl Viro return PTR_ERR(dentry); 37482ad94ae6SAl Viro 3749dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3750ce3b0f8dSAl Viro mode &= ~current_umask(); 3751dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3752be6d3e56SKentaro Takeda if (error) 3753a8104a9fSAl Viro goto out; 37541da177e4SLinus Torvalds switch (mode & S_IFMT) { 37551da177e4SLinus Torvalds case 0: case S_IFREG: 3756312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 375705d1a717SMimi Zohar if (!error) 375805d1a717SMimi Zohar ima_post_path_mknod(dentry); 37591da177e4SLinus Torvalds break; 37601da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3761dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37621da177e4SLinus Torvalds new_decode_dev(dev)); 37631da177e4SLinus Torvalds break; 37641da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3765dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37661da177e4SLinus Torvalds break; 37671da177e4SLinus Torvalds } 3768a8104a9fSAl Viro out: 3769921a1650SAl Viro done_path_create(&path, dentry); 3770972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3771972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3772972567f1SJeff Layton goto retry; 3773972567f1SJeff Layton } 37741da177e4SLinus Torvalds return error; 37751da177e4SLinus Torvalds } 37761da177e4SLinus Torvalds 377787c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 377887c4e192SDominik Brodowski unsigned int, dev) 377987c4e192SDominik Brodowski { 378087c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 378187c4e192SDominik Brodowski } 378287c4e192SDominik Brodowski 37838208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37845590ff0dSUlrich Drepper { 378587c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 37865590ff0dSUlrich Drepper } 37875590ff0dSUlrich Drepper 378818bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37891da177e4SLinus Torvalds { 3790a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37918de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37921da177e4SLinus Torvalds 37931da177e4SLinus Torvalds if (error) 37941da177e4SLinus Torvalds return error; 37951da177e4SLinus Torvalds 3796acfa4380SAl Viro if (!dir->i_op->mkdir) 37971da177e4SLinus Torvalds return -EPERM; 37981da177e4SLinus Torvalds 37991da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 38001da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 38011da177e4SLinus Torvalds if (error) 38021da177e4SLinus Torvalds return error; 38031da177e4SLinus Torvalds 38048de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 38058de52778SAl Viro return -EMLINK; 38068de52778SAl Viro 38071da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3808a74574aaSStephen Smalley if (!error) 3809f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 38101da177e4SLinus Torvalds return error; 38111da177e4SLinus Torvalds } 38124d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 38131da177e4SLinus Torvalds 38140101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 38151da177e4SLinus Torvalds { 38166902d925SDave Hansen struct dentry *dentry; 3817dae6ad8fSAl Viro struct path path; 3818dae6ad8fSAl Viro int error; 3819b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38201da177e4SLinus Torvalds 3821b76d8b82SJeff Layton retry: 3822b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38236902d925SDave Hansen if (IS_ERR(dentry)) 3824dae6ad8fSAl Viro return PTR_ERR(dentry); 38256902d925SDave Hansen 3826dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3827ce3b0f8dSAl Viro mode &= ~current_umask(); 3828dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3829a8104a9fSAl Viro if (!error) 3830dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3831921a1650SAl Viro done_path_create(&path, dentry); 3832b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3833b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3834b76d8b82SJeff Layton goto retry; 3835b76d8b82SJeff Layton } 38361da177e4SLinus Torvalds return error; 38371da177e4SLinus Torvalds } 38381da177e4SLinus Torvalds 38390101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38400101db7aSDominik Brodowski { 38410101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 38420101db7aSDominik Brodowski } 38430101db7aSDominik Brodowski 3844a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38455590ff0dSUlrich Drepper { 38460101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 38475590ff0dSUlrich Drepper } 38485590ff0dSUlrich Drepper 38491da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38501da177e4SLinus Torvalds { 38511da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38521da177e4SLinus Torvalds 38531da177e4SLinus Torvalds if (error) 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds 3856acfa4380SAl Viro if (!dir->i_op->rmdir) 38571da177e4SLinus Torvalds return -EPERM; 38581da177e4SLinus Torvalds 38591d2ef590SAl Viro dget(dentry); 38605955102cSAl Viro inode_lock(dentry->d_inode); 3861912dbc15SSage Weil 38621da177e4SLinus Torvalds error = -EBUSY; 38637af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3864912dbc15SSage Weil goto out; 3865912dbc15SSage Weil 38661da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3867912dbc15SSage Weil if (error) 3868912dbc15SSage Weil goto out; 3869912dbc15SSage Weil 38701da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3871912dbc15SSage Weil if (error) 3872912dbc15SSage Weil goto out; 3873912dbc15SSage Weil 38748767712fSAl Viro shrink_dcache_parent(dentry); 38751da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3876d83c49f3SAl Viro dont_mount(dentry); 38778ed936b5SEric W. Biederman detach_mounts(dentry); 3878116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 38791da177e4SLinus Torvalds 3880912dbc15SSage Weil out: 38815955102cSAl Viro inode_unlock(dentry->d_inode); 38821d2ef590SAl Viro dput(dentry); 3883912dbc15SSage Weil if (!error) 3884912dbc15SSage Weil d_delete(dentry); 38851da177e4SLinus Torvalds return error; 38861da177e4SLinus Torvalds } 38874d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38881da177e4SLinus Torvalds 3889f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 38901da177e4SLinus Torvalds { 38911da177e4SLinus Torvalds int error = 0; 389291a27b2aSJeff Layton struct filename *name; 38931da177e4SLinus Torvalds struct dentry *dentry; 3894f5beed75SAl Viro struct path path; 3895f5beed75SAl Viro struct qstr last; 3896f5beed75SAl Viro int type; 3897c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3898c6ee9206SJeff Layton retry: 3899c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3900c1d4dd27SAl Viro &path, &last, &type); 390191a27b2aSJeff Layton if (IS_ERR(name)) 390291a27b2aSJeff Layton return PTR_ERR(name); 39031da177e4SLinus Torvalds 3904f5beed75SAl Viro switch (type) { 39051da177e4SLinus Torvalds case LAST_DOTDOT: 39061da177e4SLinus Torvalds error = -ENOTEMPTY; 39071da177e4SLinus Torvalds goto exit1; 39081da177e4SLinus Torvalds case LAST_DOT: 39091da177e4SLinus Torvalds error = -EINVAL; 39101da177e4SLinus Torvalds goto exit1; 39111da177e4SLinus Torvalds case LAST_ROOT: 39121da177e4SLinus Torvalds error = -EBUSY; 39131da177e4SLinus Torvalds goto exit1; 39141da177e4SLinus Torvalds } 39150612d9fbSOGAWA Hirofumi 3916f5beed75SAl Viro error = mnt_want_write(path.mnt); 3917c30dabfeSJan Kara if (error) 3918c30dabfeSJan Kara goto exit1; 39190612d9fbSOGAWA Hirofumi 39205955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3921f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39221da177e4SLinus Torvalds error = PTR_ERR(dentry); 39236902d925SDave Hansen if (IS_ERR(dentry)) 39246902d925SDave Hansen goto exit2; 3925e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3926e6bc45d6STheodore Ts'o error = -ENOENT; 3927e6bc45d6STheodore Ts'o goto exit3; 3928e6bc45d6STheodore Ts'o } 3929f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3930be6d3e56SKentaro Takeda if (error) 3931c30dabfeSJan Kara goto exit3; 3932f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39330622753bSDave Hansen exit3: 39341da177e4SLinus Torvalds dput(dentry); 39356902d925SDave Hansen exit2: 39365955102cSAl Viro inode_unlock(path.dentry->d_inode); 3937f5beed75SAl Viro mnt_drop_write(path.mnt); 39381da177e4SLinus Torvalds exit1: 3939f5beed75SAl Viro path_put(&path); 39401da177e4SLinus Torvalds putname(name); 3941c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3942c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3943c6ee9206SJeff Layton goto retry; 3944c6ee9206SJeff Layton } 39451da177e4SLinus Torvalds return error; 39461da177e4SLinus Torvalds } 39471da177e4SLinus Torvalds 39483cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39495590ff0dSUlrich Drepper { 39505590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39515590ff0dSUlrich Drepper } 39525590ff0dSUlrich Drepper 3953b21996e3SJ. Bruce Fields /** 3954b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3955b21996e3SJ. Bruce Fields * @dir: parent directory 3956b21996e3SJ. Bruce Fields * @dentry: victim 3957b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3958b21996e3SJ. Bruce Fields * 3959b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3960b21996e3SJ. Bruce Fields * 3961b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3962b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3963b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3964b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3965b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3966b21996e3SJ. Bruce Fields * 3967b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3968b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3969b21996e3SJ. Bruce Fields * to be NFS exported. 3970b21996e3SJ. Bruce Fields */ 3971b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39721da177e4SLinus Torvalds { 39739accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39741da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39751da177e4SLinus Torvalds 39761da177e4SLinus Torvalds if (error) 39771da177e4SLinus Torvalds return error; 39781da177e4SLinus Torvalds 3979acfa4380SAl Viro if (!dir->i_op->unlink) 39801da177e4SLinus Torvalds return -EPERM; 39811da177e4SLinus Torvalds 39825955102cSAl Viro inode_lock(target); 39838ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39841da177e4SLinus Torvalds error = -EBUSY; 39851da177e4SLinus Torvalds else { 39861da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3987bec1052eSAl Viro if (!error) { 39885a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39895a14696cSJ. Bruce Fields if (error) 3990b21996e3SJ. Bruce Fields goto out; 39911da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39928ed936b5SEric W. Biederman if (!error) { 3993d83c49f3SAl Viro dont_mount(dentry); 39948ed936b5SEric W. Biederman detach_mounts(dentry); 3995116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 39968ed936b5SEric W. Biederman } 3997bec1052eSAl Viro } 39981da177e4SLinus Torvalds } 3999b21996e3SJ. Bruce Fields out: 40005955102cSAl Viro inode_unlock(target); 40011da177e4SLinus Torvalds 40021da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 40031da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 40049accbb97SJ. Bruce Fields fsnotify_link_count(target); 40051da177e4SLinus Torvalds d_delete(dentry); 40061da177e4SLinus Torvalds } 40070eeca283SRobert Love 40081da177e4SLinus Torvalds return error; 40091da177e4SLinus Torvalds } 40104d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 40111da177e4SLinus Torvalds 40121da177e4SLinus Torvalds /* 40131da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 40141b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 40151da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 40161da177e4SLinus Torvalds * while waiting on the I/O. 40171da177e4SLinus Torvalds */ 4018da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 40191da177e4SLinus Torvalds { 40202ad94ae6SAl Viro int error; 40211da177e4SLinus Torvalds struct dentry *dentry; 4022f5beed75SAl Viro struct path path; 4023f5beed75SAl Viro struct qstr last; 4024f5beed75SAl Viro int type; 40251da177e4SLinus Torvalds struct inode *inode = NULL; 4026b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40275d18f813SJeff Layton unsigned int lookup_flags = 0; 40285d18f813SJeff Layton retry: 4029da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 403091a27b2aSJeff Layton if (IS_ERR(name)) 403191a27b2aSJeff Layton return PTR_ERR(name); 40322ad94ae6SAl Viro 40331da177e4SLinus Torvalds error = -EISDIR; 4034f5beed75SAl Viro if (type != LAST_NORM) 40351da177e4SLinus Torvalds goto exit1; 40360612d9fbSOGAWA Hirofumi 4037f5beed75SAl Viro error = mnt_want_write(path.mnt); 4038c30dabfeSJan Kara if (error) 4039c30dabfeSJan Kara goto exit1; 4040b21996e3SJ. Bruce Fields retry_deleg: 40415955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4042f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40431da177e4SLinus Torvalds error = PTR_ERR(dentry); 40441da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40451da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4046f5beed75SAl Viro if (last.name[last.len]) 404750338b88STörök Edwin goto slashes; 40481da177e4SLinus Torvalds inode = dentry->d_inode; 4049b18825a7SDavid Howells if (d_is_negative(dentry)) 4050e6bc45d6STheodore Ts'o goto slashes; 40517de9c6eeSAl Viro ihold(inode); 4052f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4053be6d3e56SKentaro Takeda if (error) 4054c30dabfeSJan Kara goto exit2; 4055f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40561da177e4SLinus Torvalds exit2: 40571da177e4SLinus Torvalds dput(dentry); 40581da177e4SLinus Torvalds } 40595955102cSAl Viro inode_unlock(path.dentry->d_inode); 40601da177e4SLinus Torvalds if (inode) 40611da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4062b21996e3SJ. Bruce Fields inode = NULL; 4063b21996e3SJ. Bruce Fields if (delegated_inode) { 40645a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4065b21996e3SJ. Bruce Fields if (!error) 4066b21996e3SJ. Bruce Fields goto retry_deleg; 4067b21996e3SJ. Bruce Fields } 4068f5beed75SAl Viro mnt_drop_write(path.mnt); 40691da177e4SLinus Torvalds exit1: 4070f5beed75SAl Viro path_put(&path); 40715d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40725d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40735d18f813SJeff Layton inode = NULL; 40745d18f813SJeff Layton goto retry; 40755d18f813SJeff Layton } 4076da2f1362SChristoph Hellwig putname(name); 40771da177e4SLinus Torvalds return error; 40781da177e4SLinus Torvalds 40791da177e4SLinus Torvalds slashes: 4080b18825a7SDavid Howells if (d_is_negative(dentry)) 4081b18825a7SDavid Howells error = -ENOENT; 408244b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4083b18825a7SDavid Howells error = -EISDIR; 4084b18825a7SDavid Howells else 4085b18825a7SDavid Howells error = -ENOTDIR; 40861da177e4SLinus Torvalds goto exit2; 40871da177e4SLinus Torvalds } 40881da177e4SLinus Torvalds 40892e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40905590ff0dSUlrich Drepper { 40915590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40925590ff0dSUlrich Drepper return -EINVAL; 40935590ff0dSUlrich Drepper 40945590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40955590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40965590ff0dSUlrich Drepper 4097da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40985590ff0dSUlrich Drepper } 40995590ff0dSUlrich Drepper 41003480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 41015590ff0dSUlrich Drepper { 4102da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 41035590ff0dSUlrich Drepper } 41045590ff0dSUlrich Drepper 4105db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 41061da177e4SLinus Torvalds { 4107a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 41081da177e4SLinus Torvalds 41091da177e4SLinus Torvalds if (error) 41101da177e4SLinus Torvalds return error; 41111da177e4SLinus Torvalds 4112acfa4380SAl Viro if (!dir->i_op->symlink) 41131da177e4SLinus Torvalds return -EPERM; 41141da177e4SLinus Torvalds 41151da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 41161da177e4SLinus Torvalds if (error) 41171da177e4SLinus Torvalds return error; 41181da177e4SLinus Torvalds 41191da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4120a74574aaSStephen Smalley if (!error) 4121f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41221da177e4SLinus Torvalds return error; 41231da177e4SLinus Torvalds } 41244d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41251da177e4SLinus Torvalds 4126b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4127b724e846SDominik Brodowski const char __user *newname) 41281da177e4SLinus Torvalds { 41292ad94ae6SAl Viro int error; 413091a27b2aSJeff Layton struct filename *from; 41316902d925SDave Hansen struct dentry *dentry; 4132dae6ad8fSAl Viro struct path path; 4133f46d3567SJeff Layton unsigned int lookup_flags = 0; 41341da177e4SLinus Torvalds 41351da177e4SLinus Torvalds from = getname(oldname); 41361da177e4SLinus Torvalds if (IS_ERR(from)) 41371da177e4SLinus Torvalds return PTR_ERR(from); 4138f46d3567SJeff Layton retry: 4139f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41401da177e4SLinus Torvalds error = PTR_ERR(dentry); 41416902d925SDave Hansen if (IS_ERR(dentry)) 4142dae6ad8fSAl Viro goto out_putname; 41436902d925SDave Hansen 414491a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4145a8104a9fSAl Viro if (!error) 414691a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4147921a1650SAl Viro done_path_create(&path, dentry); 4148f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4149f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4150f46d3567SJeff Layton goto retry; 4151f46d3567SJeff Layton } 41526902d925SDave Hansen out_putname: 41531da177e4SLinus Torvalds putname(from); 41541da177e4SLinus Torvalds return error; 41551da177e4SLinus Torvalds } 41561da177e4SLinus Torvalds 4157b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4158b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4159b724e846SDominik Brodowski { 4160b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4161b724e846SDominik Brodowski } 4162b724e846SDominik Brodowski 41633480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41645590ff0dSUlrich Drepper { 4165b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 41665590ff0dSUlrich Drepper } 41675590ff0dSUlrich Drepper 4168146a8595SJ. Bruce Fields /** 4169146a8595SJ. Bruce Fields * vfs_link - create a new link 4170146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4171146a8595SJ. Bruce Fields * @dir: new parent 4172146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4173146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4174146a8595SJ. Bruce Fields * 4175146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4176146a8595SJ. Bruce Fields * 4177146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4178146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4179146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4180146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4181146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4182146a8595SJ. Bruce Fields * 4183146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4184146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4185146a8595SJ. Bruce Fields * to be NFS exported. 4186146a8595SJ. Bruce Fields */ 4187146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41881da177e4SLinus Torvalds { 41891da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41908de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41911da177e4SLinus Torvalds int error; 41921da177e4SLinus Torvalds 41931da177e4SLinus Torvalds if (!inode) 41941da177e4SLinus Torvalds return -ENOENT; 41951da177e4SLinus Torvalds 4196a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41971da177e4SLinus Torvalds if (error) 41981da177e4SLinus Torvalds return error; 41991da177e4SLinus Torvalds 42001da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 42011da177e4SLinus Torvalds return -EXDEV; 42021da177e4SLinus Torvalds 42031da177e4SLinus Torvalds /* 42041da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 42051da177e4SLinus Torvalds */ 42061da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 42071da177e4SLinus Torvalds return -EPERM; 42080bd23d09SEric W. Biederman /* 42090bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 42100bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 42110bd23d09SEric W. Biederman * the vfs. 42120bd23d09SEric W. Biederman */ 42130bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 42140bd23d09SEric W. Biederman return -EPERM; 4215acfa4380SAl Viro if (!dir->i_op->link) 42161da177e4SLinus Torvalds return -EPERM; 42177e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 42181da177e4SLinus Torvalds return -EPERM; 42191da177e4SLinus Torvalds 42201da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 42211da177e4SLinus Torvalds if (error) 42221da177e4SLinus Torvalds return error; 42231da177e4SLinus Torvalds 42245955102cSAl Viro inode_lock(inode); 4225aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4226f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4227aae8a97dSAneesh Kumar K.V error = -ENOENT; 42288de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 42298de52778SAl Viro error = -EMLINK; 4230146a8595SJ. Bruce Fields else { 4231146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4232146a8595SJ. Bruce Fields if (!error) 42331da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4234146a8595SJ. Bruce Fields } 4235f4e0c30cSAl Viro 4236f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4237f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4238f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4239f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4240f4e0c30cSAl Viro } 42415955102cSAl Viro inode_unlock(inode); 4242e31e14ecSStephen Smalley if (!error) 42437e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42441da177e4SLinus Torvalds return error; 42451da177e4SLinus Torvalds } 42464d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42471da177e4SLinus Torvalds 42481da177e4SLinus Torvalds /* 42491da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42501da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42511da177e4SLinus Torvalds * newname. --KAB 42521da177e4SLinus Torvalds * 42531da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42541da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42551da177e4SLinus Torvalds * and other special files. --ADM 42561da177e4SLinus Torvalds */ 425746ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 425846ea89ebSDominik Brodowski const char __user *newname, int flags) 42591da177e4SLinus Torvalds { 42601da177e4SLinus Torvalds struct dentry *new_dentry; 4261dae6ad8fSAl Viro struct path old_path, new_path; 4262146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 426311a7b371SAneesh Kumar K.V int how = 0; 42641da177e4SLinus Torvalds int error; 42651da177e4SLinus Torvalds 426611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4267c04030e1SUlrich Drepper return -EINVAL; 426811a7b371SAneesh Kumar K.V /* 4269f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4270f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4271f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 427211a7b371SAneesh Kumar K.V */ 4273f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4274f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4275f0cc6ffbSLinus Torvalds return -ENOENT; 427611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4277f0cc6ffbSLinus Torvalds } 4278c04030e1SUlrich Drepper 427911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 428011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4281442e31caSJeff Layton retry: 428211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42831da177e4SLinus Torvalds if (error) 42842ad94ae6SAl Viro return error; 42852ad94ae6SAl Viro 4286442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4287442e31caSJeff Layton (how & LOOKUP_REVAL)); 42881da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42896902d925SDave Hansen if (IS_ERR(new_dentry)) 4290dae6ad8fSAl Viro goto out; 4291dae6ad8fSAl Viro 4292dae6ad8fSAl Viro error = -EXDEV; 4293dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4294dae6ad8fSAl Viro goto out_dput; 4295800179c9SKees Cook error = may_linkat(&old_path); 4296800179c9SKees Cook if (unlikely(error)) 4297800179c9SKees Cook goto out_dput; 4298dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4299be6d3e56SKentaro Takeda if (error) 4300a8104a9fSAl Viro goto out_dput; 4301146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 430275c3f29dSDave Hansen out_dput: 4303921a1650SAl Viro done_path_create(&new_path, new_dentry); 4304146a8595SJ. Bruce Fields if (delegated_inode) { 4305146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4306d22e6338SOleg Drokin if (!error) { 4307d22e6338SOleg Drokin path_put(&old_path); 4308146a8595SJ. Bruce Fields goto retry; 4309146a8595SJ. Bruce Fields } 4310d22e6338SOleg Drokin } 4311442e31caSJeff Layton if (retry_estale(error, how)) { 4312d22e6338SOleg Drokin path_put(&old_path); 4313442e31caSJeff Layton how |= LOOKUP_REVAL; 4314442e31caSJeff Layton goto retry; 4315442e31caSJeff Layton } 43161da177e4SLinus Torvalds out: 43172d8f3038SAl Viro path_put(&old_path); 43181da177e4SLinus Torvalds 43191da177e4SLinus Torvalds return error; 43201da177e4SLinus Torvalds } 43211da177e4SLinus Torvalds 432246ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 432346ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 432446ea89ebSDominik Brodowski { 432546ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 432646ea89ebSDominik Brodowski } 432746ea89ebSDominik Brodowski 43283480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 43295590ff0dSUlrich Drepper { 433046ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43315590ff0dSUlrich Drepper } 43325590ff0dSUlrich Drepper 4333bc27027aSMiklos Szeredi /** 4334bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4335bc27027aSMiklos Szeredi * @old_dir: parent of source 4336bc27027aSMiklos Szeredi * @old_dentry: source 4337bc27027aSMiklos Szeredi * @new_dir: parent of destination 4338bc27027aSMiklos Szeredi * @new_dentry: destination 4339bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4340520c8b16SMiklos Szeredi * @flags: rename flags 4341bc27027aSMiklos Szeredi * 4342bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4343bc27027aSMiklos Szeredi * 4344bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4345bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4346bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4347bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4348bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4349bc27027aSMiklos Szeredi * so. 4350bc27027aSMiklos Szeredi * 4351bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4352bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4353bc27027aSMiklos Szeredi * to be NFS exported. 4354bc27027aSMiklos Szeredi * 43551da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43561da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43571da177e4SLinus Torvalds * Problems: 43580117d427SMauro Carvalho Chehab * 4359d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43601da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43611da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4362a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43631da177e4SLinus Torvalds * story. 43646cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43656cedba89SJ. Bruce Fields * and source (if it is not a directory). 43661b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43671da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43681da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4369a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43701da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43711da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43721da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4373a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43741da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43751da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43761da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4377e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43781b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43791da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4380c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43811da177e4SLinus Torvalds * locking]. 43821da177e4SLinus Torvalds */ 43831da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43848e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4385520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43861da177e4SLinus Torvalds { 43871da177e4SLinus Torvalds int error; 4388bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4389bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4390bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4391da1ce067SMiklos Szeredi bool new_is_dir = false; 4392da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 439349d31c2fSAl Viro struct name_snapshot old_name; 43941da177e4SLinus Torvalds 43958d3e2936SMiklos Szeredi if (source == target) 43961da177e4SLinus Torvalds return 0; 43971da177e4SLinus Torvalds 43981da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43991da177e4SLinus Torvalds if (error) 44001da177e4SLinus Torvalds return error; 44011da177e4SLinus Torvalds 4402da1ce067SMiklos Szeredi if (!target) { 4403a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4404da1ce067SMiklos Szeredi } else { 4405da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4406da1ce067SMiklos Szeredi 4407da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44081da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4409da1ce067SMiklos Szeredi else 4410da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4411da1ce067SMiklos Szeredi } 44121da177e4SLinus Torvalds if (error) 44131da177e4SLinus Torvalds return error; 44141da177e4SLinus Torvalds 44152773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 44161da177e4SLinus Torvalds return -EPERM; 44171da177e4SLinus Torvalds 4418bc27027aSMiklos Szeredi /* 4419bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4420bc27027aSMiklos Szeredi * we'll need to flip '..'. 4421bc27027aSMiklos Szeredi */ 4422da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4423da1ce067SMiklos Szeredi if (is_dir) { 4424bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4425bc27027aSMiklos Szeredi if (error) 4426bc27027aSMiklos Szeredi return error; 4427bc27027aSMiklos Szeredi } 4428da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4429da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4430da1ce067SMiklos Szeredi if (error) 4431da1ce067SMiklos Szeredi return error; 4432da1ce067SMiklos Szeredi } 4433da1ce067SMiklos Szeredi } 44340eeca283SRobert Love 44350b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44360b3974ebSMiklos Szeredi flags); 4437bc27027aSMiklos Szeredi if (error) 4438bc27027aSMiklos Szeredi return error; 4439bc27027aSMiklos Szeredi 444049d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4441bc27027aSMiklos Szeredi dget(new_dentry); 4442da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4443bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4444bc27027aSMiklos Szeredi else if (target) 44455955102cSAl Viro inode_lock(target); 4446bc27027aSMiklos Szeredi 4447bc27027aSMiklos Szeredi error = -EBUSY; 44487af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4449bc27027aSMiklos Szeredi goto out; 4450bc27027aSMiklos Szeredi 4451da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4452bc27027aSMiklos Szeredi error = -EMLINK; 4453da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4454bc27027aSMiklos Szeredi goto out; 4455da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4456da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4457da1ce067SMiklos Szeredi goto out; 4458da1ce067SMiklos Szeredi } 4459da1ce067SMiklos Szeredi if (!is_dir) { 4460bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4461bc27027aSMiklos Szeredi if (error) 4462bc27027aSMiklos Szeredi goto out; 4463da1ce067SMiklos Szeredi } 4464da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4465bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4466bc27027aSMiklos Szeredi if (error) 4467bc27027aSMiklos Szeredi goto out; 4468bc27027aSMiklos Szeredi } 4469520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4470520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4471bc27027aSMiklos Szeredi if (error) 4472bc27027aSMiklos Szeredi goto out; 4473bc27027aSMiklos Szeredi 4474da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44758767712fSAl Viro if (is_dir) { 44768767712fSAl Viro shrink_dcache_parent(new_dentry); 4477bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 44788767712fSAl Viro } 4479bc27027aSMiklos Szeredi dont_mount(new_dentry); 44808ed936b5SEric W. Biederman detach_mounts(new_dentry); 4481bc27027aSMiklos Szeredi } 4482da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4483da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4484bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4485da1ce067SMiklos Szeredi else 4486da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4487da1ce067SMiklos Szeredi } 4488bc27027aSMiklos Szeredi out: 4489da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4490bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4491bc27027aSMiklos Szeredi else if (target) 44925955102cSAl Viro inode_unlock(target); 4493bc27027aSMiklos Szeredi dput(new_dentry); 4494da1ce067SMiklos Szeredi if (!error) { 4495f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4496da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4497da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4498f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4499da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4500da1ce067SMiklos Szeredi } 4501da1ce067SMiklos Szeredi } 450249d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 45030eeca283SRobert Love 45041da177e4SLinus Torvalds return error; 45051da177e4SLinus Torvalds } 45064d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 45071da177e4SLinus Torvalds 4508ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4509ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 45101da177e4SLinus Torvalds { 45111da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 45121da177e4SLinus Torvalds struct dentry *trap; 4513f5beed75SAl Viro struct path old_path, new_path; 4514f5beed75SAl Viro struct qstr old_last, new_last; 4515f5beed75SAl Viro int old_type, new_type; 45168e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 451791a27b2aSJeff Layton struct filename *from; 451891a27b2aSJeff Layton struct filename *to; 4519f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4520c6a94284SJeff Layton bool should_retry = false; 45212ad94ae6SAl Viro int error; 4522520c8b16SMiklos Szeredi 45230d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4524da1ce067SMiklos Szeredi return -EINVAL; 4525da1ce067SMiklos Szeredi 45260d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 45270d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4528520c8b16SMiklos Szeredi return -EINVAL; 4529520c8b16SMiklos Szeredi 45300d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 45310d7a8555SMiklos Szeredi return -EPERM; 45320d7a8555SMiklos Szeredi 4533f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4534f5beed75SAl Viro target_flags = 0; 4535f5beed75SAl Viro 4536c6a94284SJeff Layton retry: 4537c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4538c1d4dd27SAl Viro &old_path, &old_last, &old_type); 453991a27b2aSJeff Layton if (IS_ERR(from)) { 454091a27b2aSJeff Layton error = PTR_ERR(from); 45411da177e4SLinus Torvalds goto exit; 454291a27b2aSJeff Layton } 45431da177e4SLinus Torvalds 4544c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4545c1d4dd27SAl Viro &new_path, &new_last, &new_type); 454691a27b2aSJeff Layton if (IS_ERR(to)) { 454791a27b2aSJeff Layton error = PTR_ERR(to); 45481da177e4SLinus Torvalds goto exit1; 454991a27b2aSJeff Layton } 45501da177e4SLinus Torvalds 45511da177e4SLinus Torvalds error = -EXDEV; 4552f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45531da177e4SLinus Torvalds goto exit2; 45541da177e4SLinus Torvalds 45551da177e4SLinus Torvalds error = -EBUSY; 4556f5beed75SAl Viro if (old_type != LAST_NORM) 45571da177e4SLinus Torvalds goto exit2; 45581da177e4SLinus Torvalds 45590a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45600a7c3937SMiklos Szeredi error = -EEXIST; 4561f5beed75SAl Viro if (new_type != LAST_NORM) 45621da177e4SLinus Torvalds goto exit2; 45631da177e4SLinus Torvalds 4564f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4565c30dabfeSJan Kara if (error) 4566c30dabfeSJan Kara goto exit2; 4567c30dabfeSJan Kara 45688e6d782cSJ. Bruce Fields retry_deleg: 4569f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45701da177e4SLinus Torvalds 4571f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45721da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45731da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45741da177e4SLinus Torvalds goto exit3; 45751da177e4SLinus Torvalds /* source must exist */ 45761da177e4SLinus Torvalds error = -ENOENT; 4577b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45781da177e4SLinus Torvalds goto exit4; 4579f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45801da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45811da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45821da177e4SLinus Torvalds goto exit4; 45830a7c3937SMiklos Szeredi error = -EEXIST; 45840a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45850a7c3937SMiklos Szeredi goto exit5; 4586da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4587da1ce067SMiklos Szeredi error = -ENOENT; 4588da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4589da1ce067SMiklos Szeredi goto exit5; 4590da1ce067SMiklos Szeredi 4591da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4592da1ce067SMiklos Szeredi error = -ENOTDIR; 4593f5beed75SAl Viro if (new_last.name[new_last.len]) 4594da1ce067SMiklos Szeredi goto exit5; 4595da1ce067SMiklos Szeredi } 4596da1ce067SMiklos Szeredi } 45970a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45980a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45990a7c3937SMiklos Szeredi error = -ENOTDIR; 4600f5beed75SAl Viro if (old_last.name[old_last.len]) 46010a7c3937SMiklos Szeredi goto exit5; 4602f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 46030a7c3937SMiklos Szeredi goto exit5; 46040a7c3937SMiklos Szeredi } 46050a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 46060a7c3937SMiklos Szeredi error = -EINVAL; 46070a7c3937SMiklos Szeredi if (old_dentry == trap) 46080a7c3937SMiklos Szeredi goto exit5; 46091da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4610da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 46111da177e4SLinus Torvalds error = -ENOTEMPTY; 46121da177e4SLinus Torvalds if (new_dentry == trap) 46131da177e4SLinus Torvalds goto exit5; 46141da177e4SLinus Torvalds 4615f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4616f5beed75SAl Viro &new_path, new_dentry, flags); 4617be6d3e56SKentaro Takeda if (error) 4618c30dabfeSJan Kara goto exit5; 4619f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4620f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4621520c8b16SMiklos Szeredi &delegated_inode, flags); 46221da177e4SLinus Torvalds exit5: 46231da177e4SLinus Torvalds dput(new_dentry); 46241da177e4SLinus Torvalds exit4: 46251da177e4SLinus Torvalds dput(old_dentry); 46261da177e4SLinus Torvalds exit3: 4627f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 46288e6d782cSJ. Bruce Fields if (delegated_inode) { 46298e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 46308e6d782cSJ. Bruce Fields if (!error) 46318e6d782cSJ. Bruce Fields goto retry_deleg; 46328e6d782cSJ. Bruce Fields } 4633f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46341da177e4SLinus Torvalds exit2: 4635c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4636c6a94284SJeff Layton should_retry = true; 4637f5beed75SAl Viro path_put(&new_path); 46382ad94ae6SAl Viro putname(to); 46391da177e4SLinus Torvalds exit1: 4640f5beed75SAl Viro path_put(&old_path); 46411da177e4SLinus Torvalds putname(from); 4642c6a94284SJeff Layton if (should_retry) { 4643c6a94284SJeff Layton should_retry = false; 4644c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4645c6a94284SJeff Layton goto retry; 4646c6a94284SJeff Layton } 46472ad94ae6SAl Viro exit: 46481da177e4SLinus Torvalds return error; 46491da177e4SLinus Torvalds } 46501da177e4SLinus Torvalds 4651ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4652ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4653ee81feb6SDominik Brodowski { 4654ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4655ee81feb6SDominik Brodowski } 4656ee81feb6SDominik Brodowski 4657520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4658520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4659520c8b16SMiklos Szeredi { 4660ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4661520c8b16SMiklos Szeredi } 4662520c8b16SMiklos Szeredi 4663a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46645590ff0dSUlrich Drepper { 4665ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46665590ff0dSUlrich Drepper } 46675590ff0dSUlrich Drepper 4668787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4669787fb6bcSMiklos Szeredi { 4670787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4671787fb6bcSMiklos Szeredi if (error) 4672787fb6bcSMiklos Szeredi return error; 4673787fb6bcSMiklos Szeredi 4674787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4675787fb6bcSMiklos Szeredi return -EPERM; 4676787fb6bcSMiklos Szeredi 4677787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4678787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4679787fb6bcSMiklos Szeredi } 4680787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4681787fb6bcSMiklos Szeredi 46825d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46831da177e4SLinus Torvalds { 46845d826c84SAl Viro int len = PTR_ERR(link); 46851da177e4SLinus Torvalds if (IS_ERR(link)) 46861da177e4SLinus Torvalds goto out; 46871da177e4SLinus Torvalds 46881da177e4SLinus Torvalds len = strlen(link); 46891da177e4SLinus Torvalds if (len > (unsigned) buflen) 46901da177e4SLinus Torvalds len = buflen; 46911da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46921da177e4SLinus Torvalds len = -EFAULT; 46931da177e4SLinus Torvalds out: 46941da177e4SLinus Torvalds return len; 46951da177e4SLinus Torvalds } 46961da177e4SLinus Torvalds 4697d60874cdSMiklos Szeredi /** 4698fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4699fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4700fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4701fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4702fd4a0edfSMiklos Szeredi * 4703fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4704fd4a0edfSMiklos Szeredi * 4705fd4a0edfSMiklos Szeredi * Does not call security hook. 4706fd4a0edfSMiklos Szeredi */ 4707fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4708fd4a0edfSMiklos Szeredi { 4709fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4710f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4711f2df5da6SAl Viro const char *link; 4712f2df5da6SAl Viro int res; 4713fd4a0edfSMiklos Szeredi 471476fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 471576fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 471676fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 471776fca90eSMiklos Szeredi 471876fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4719fd4a0edfSMiklos Szeredi return -EINVAL; 4720fd4a0edfSMiklos Szeredi 472176fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 472276fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 472376fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 472476fca90eSMiklos Szeredi } 472576fca90eSMiklos Szeredi 47264c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4727f2df5da6SAl Viro if (!link) { 4728f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4729f2df5da6SAl Viro if (IS_ERR(link)) 4730f2df5da6SAl Viro return PTR_ERR(link); 4731f2df5da6SAl Viro } 4732f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4733f2df5da6SAl Viro do_delayed_call(&done); 4734f2df5da6SAl Viro return res; 4735fd4a0edfSMiklos Szeredi } 4736fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 47371da177e4SLinus Torvalds 4738d60874cdSMiklos Szeredi /** 4739d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4740d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4741d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4742d60874cdSMiklos Szeredi * 4743d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4744d60874cdSMiklos Szeredi * 4745d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4746d60874cdSMiklos Szeredi * 4747d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4748d60874cdSMiklos Szeredi */ 4749d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4750d60874cdSMiklos Szeredi { 4751d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4752d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4753d60874cdSMiklos Szeredi 4754d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4755d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4756d60874cdSMiklos Szeredi if (!res) 4757d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4758d60874cdSMiklos Szeredi } 4759d60874cdSMiklos Szeredi return res; 4760d60874cdSMiklos Szeredi } 4761d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4762d60874cdSMiklos Szeredi 47631da177e4SLinus Torvalds /* get the link contents into pagecache */ 47646b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4765fceef393SAl Viro struct delayed_call *callback) 47661da177e4SLinus Torvalds { 4767ebd09abbSDuane Griffin char *kaddr; 47681da177e4SLinus Torvalds struct page *page; 47696b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47706b255391SAl Viro 4771d3883d4fSAl Viro if (!dentry) { 4772d3883d4fSAl Viro page = find_get_page(mapping, 0); 4773d3883d4fSAl Viro if (!page) 47746b255391SAl Viro return ERR_PTR(-ECHILD); 4775d3883d4fSAl Viro if (!PageUptodate(page)) { 4776d3883d4fSAl Viro put_page(page); 4777d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4778d3883d4fSAl Viro } 4779d3883d4fSAl Viro } else { 4780090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47811da177e4SLinus Torvalds if (IS_ERR(page)) 47826fe6900eSNick Piggin return (char*)page; 4783d3883d4fSAl Viro } 4784fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 478521fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 478621fc61c7SAl Viro kaddr = page_address(page); 47876b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4788ebd09abbSDuane Griffin return kaddr; 47891da177e4SLinus Torvalds } 47901da177e4SLinus Torvalds 47916b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47921da177e4SLinus Torvalds 4793fceef393SAl Viro void page_put_link(void *arg) 47941da177e4SLinus Torvalds { 4795fceef393SAl Viro put_page(arg); 47961da177e4SLinus Torvalds } 47974d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47981da177e4SLinus Torvalds 4799aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4800aa80deabSAl Viro { 4801fceef393SAl Viro DEFINE_DELAYED_CALL(done); 48026b255391SAl Viro int res = readlink_copy(buffer, buflen, 48036b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4804fceef393SAl Viro &done)); 4805fceef393SAl Viro do_delayed_call(&done); 4806aa80deabSAl Viro return res; 4807aa80deabSAl Viro } 4808aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4809aa80deabSAl Viro 481054566b2cSNick Piggin /* 481154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 481254566b2cSNick Piggin */ 481354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 48141da177e4SLinus Torvalds { 48151da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 48160adb25d2SKirill Korotaev struct page *page; 4817afddba49SNick Piggin void *fsdata; 4818beb497abSDmitriy Monakhov int err; 4819c718a975STetsuo Handa unsigned int flags = 0; 482054566b2cSNick Piggin if (nofs) 482154566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 48221da177e4SLinus Torvalds 48237e53cac4SNeilBrown retry: 4824afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 482554566b2cSNick Piggin flags, &page, &fsdata); 48261da177e4SLinus Torvalds if (err) 4827afddba49SNick Piggin goto fail; 4828afddba49SNick Piggin 482921fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4830afddba49SNick Piggin 4831afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4832afddba49SNick Piggin page, fsdata); 48331da177e4SLinus Torvalds if (err < 0) 48341da177e4SLinus Torvalds goto fail; 4835afddba49SNick Piggin if (err < len-1) 4836afddba49SNick Piggin goto retry; 4837afddba49SNick Piggin 48381da177e4SLinus Torvalds mark_inode_dirty(inode); 48391da177e4SLinus Torvalds return 0; 48401da177e4SLinus Torvalds fail: 48411da177e4SLinus Torvalds return err; 48421da177e4SLinus Torvalds } 48434d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48441da177e4SLinus Torvalds 48450adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48460adb25d2SKirill Korotaev { 48470adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4848c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48490adb25d2SKirill Korotaev } 48504d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48510adb25d2SKirill Korotaev 485292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48536b255391SAl Viro .get_link = page_get_link, 48541da177e4SLinus Torvalds }; 48551da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4856