1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 4949883d185SAl Viro unsigned seq, m_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 506fceef393SAl Viro struct inode *link_inode; 5079883d185SAl Viro unsigned root_seq; 5089883d185SAl Viro int dfd; 5093859a271SKees Cook } __randomize_layout; 5101f55a6ecSAl Viro 5119883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 512894bc8c4SAl Viro { 513756daf26SNeilBrown struct nameidata *old = current->nameidata; 514756daf26SNeilBrown p->stack = p->internal; 515c8a53ee5SAl Viro p->dfd = dfd; 516c8a53ee5SAl Viro p->name = name; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5189883d185SAl Viro p->saved = old; 519756daf26SNeilBrown current->nameidata = p; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 5229883d185SAl Viro static void restore_nameidata(void) 523894bc8c4SAl Viro { 5249883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529e1a63bbcSAl Viro if (now->stack != now->internal) 530756daf26SNeilBrown kfree(now->stack); 531894bc8c4SAl Viro } 532894bc8c4SAl Viro 533894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 534894bc8c4SAl Viro { 535bc40aee0SAl Viro struct saved *p; 536bc40aee0SAl Viro 537bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5386da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 539bc40aee0SAl Viro GFP_ATOMIC); 540bc40aee0SAl Viro if (unlikely(!p)) 541bc40aee0SAl Viro return -ECHILD; 542bc40aee0SAl Viro } else { 5436da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 544894bc8c4SAl Viro GFP_KERNEL); 545894bc8c4SAl Viro if (unlikely(!p)) 546894bc8c4SAl Viro return -ENOMEM; 547bc40aee0SAl Viro } 548894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 549894bc8c4SAl Viro nd->stack = p; 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro } 552894bc8c4SAl Viro 553397d425dSEric W. Biederman /** 554397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 555397d425dSEric W. Biederman * @path: nameidate to verify 556397d425dSEric W. Biederman * 557397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 558397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 559397d425dSEric W. Biederman */ 560397d425dSEric W. Biederman static bool path_connected(const struct path *path) 561397d425dSEric W. Biederman { 562397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 56395dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 564397d425dSEric W. Biederman 56595dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56695dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 567397d425dSEric W. Biederman return true; 568397d425dSEric W. Biederman 569397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 570397d425dSEric W. Biederman } 571397d425dSEric W. Biederman 572894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 573894bc8c4SAl Viro { 574da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 575894bc8c4SAl Viro return 0; 576894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 577894bc8c4SAl Viro return 0; 578894bc8c4SAl Viro return __nd_alloc_stack(nd); 579894bc8c4SAl Viro } 580894bc8c4SAl Viro 5817973387aSAl Viro static void drop_links(struct nameidata *nd) 5827973387aSAl Viro { 5837973387aSAl Viro int i = nd->depth; 5847973387aSAl Viro while (i--) { 5857973387aSAl Viro struct saved *last = nd->stack + i; 586fceef393SAl Viro do_delayed_call(&last->done); 587fceef393SAl Viro clear_delayed_call(&last->done); 5887973387aSAl Viro } 5897973387aSAl Viro } 5907973387aSAl Viro 5917973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5927973387aSAl Viro { 5937973387aSAl Viro drop_links(nd); 5947973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5957973387aSAl Viro int i; 5967973387aSAl Viro path_put(&nd->path); 5977973387aSAl Viro for (i = 0; i < nd->depth; i++) 5987973387aSAl Viro path_put(&nd->stack[i].link); 59984a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 600102b8af2SAl Viro path_put(&nd->root); 60184a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 602102b8af2SAl Viro } 6037973387aSAl Viro } else { 6047973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6057973387aSAl Viro rcu_read_unlock(); 6067973387aSAl Viro } 6077973387aSAl Viro nd->depth = 0; 6087973387aSAl Viro } 6097973387aSAl Viro 6107973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6117973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6127973387aSAl Viro struct path *path, unsigned seq) 6137973387aSAl Viro { 6147973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6157973387aSAl Viro if (unlikely(res)) { 6167973387aSAl Viro if (res > 0) 6177973387aSAl Viro path->mnt = NULL; 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6227973387aSAl Viro path->dentry = NULL; 6237973387aSAl Viro return false; 6247973387aSAl Viro } 6257973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6267973387aSAl Viro } 6277973387aSAl Viro 6287973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6297973387aSAl Viro { 6307973387aSAl Viro int i; 6317973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6327973387aSAl Viro struct saved *last = nd->stack + i; 6337973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6347973387aSAl Viro drop_links(nd); 6357973387aSAl Viro nd->depth = i + 1; 6367973387aSAl Viro return false; 6377973387aSAl Viro } 6387973387aSAl Viro } 6397973387aSAl Viro return true; 6407973387aSAl Viro } 6417973387aSAl Viro 642ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 643ee594bffSAl Viro { 644ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 645ee594bffSAl Viro return true; 64684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 647ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 648ee594bffSAl Viro } 649ee594bffSAl Viro 65019660af7SAl Viro /* 65131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 65819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 65931e6b01fSNick Piggin */ 66031e6b01fSNick Piggin 66131e6b01fSNick Piggin /** 66219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66319660af7SAl Viro * @nd: nameidata pathwalk data 66439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 66531e6b01fSNick Piggin * 6664675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6674675ac39SAl Viro * for ref-walk mode. 6684675ac39SAl Viro * Must be called from rcu-walk context. 6697973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6707973387aSAl Viro * terminate_walk(). 67131e6b01fSNick Piggin */ 6724675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 67331e6b01fSNick Piggin { 67431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 67531e6b01fSNick Piggin 67631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 677e5c832d5SLinus Torvalds 678e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6797973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6804675ac39SAl Viro goto out1; 68184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 68284a2bd39SAl Viro goto out; 683ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6844675ac39SAl Viro goto out; 6854675ac39SAl Viro rcu_read_unlock(); 6864675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6874675ac39SAl Viro return 0; 6884675ac39SAl Viro 68984a2bd39SAl Viro out1: 6904675ac39SAl Viro nd->path.mnt = NULL; 6914675ac39SAl Viro nd->path.dentry = NULL; 6924675ac39SAl Viro out: 6934675ac39SAl Viro rcu_read_unlock(); 6944675ac39SAl Viro return -ECHILD; 6954675ac39SAl Viro } 6964675ac39SAl Viro 6974675ac39SAl Viro /** 6984675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 6994675ac39SAl Viro * @nd: nameidata pathwalk data 7004675ac39SAl Viro * @dentry: child of nd->path.dentry 7014675ac39SAl Viro * @seq: seq number to check dentry against 7024675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7034675ac39SAl Viro * 7044675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7054675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7064675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7074675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7084675ac39SAl Viro * terminate_walk(). 7094675ac39SAl Viro */ 7104675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7114675ac39SAl Viro { 7124675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7134675ac39SAl Viro 7144675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7154675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7164675ac39SAl Viro goto out2; 7177973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7187973387aSAl Viro goto out2; 7194675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7207973387aSAl Viro goto out1; 72148a066e7SAl Viro 72215570086SLinus Torvalds /* 7234675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7244675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7254675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7264675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7274675ac39SAl Viro * know the parent must still be valid if the child sequence number is 72815570086SLinus Torvalds */ 7294675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 730e5c832d5SLinus Torvalds goto out; 73184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 73284a2bd39SAl Viro goto out_dput; 733e5c832d5SLinus Torvalds /* 734e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 735e5c832d5SLinus Torvalds * still valid and get it if required. 736e5c832d5SLinus Torvalds */ 73784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 73884a2bd39SAl Viro goto out_dput; 7398b61e74fSAl Viro rcu_read_unlock(); 74031e6b01fSNick Piggin return 0; 74119660af7SAl Viro 7427973387aSAl Viro out2: 7437973387aSAl Viro nd->path.mnt = NULL; 7447973387aSAl Viro out1: 7457973387aSAl Viro nd->path.dentry = NULL; 746e5c832d5SLinus Torvalds out: 7478b61e74fSAl Viro rcu_read_unlock(); 74884a2bd39SAl Viro return -ECHILD; 74984a2bd39SAl Viro out_dput: 75084a2bd39SAl Viro rcu_read_unlock(); 75184a2bd39SAl Viro dput(dentry); 75231e6b01fSNick Piggin return -ECHILD; 75331e6b01fSNick Piggin } 75431e6b01fSNick Piggin 7554ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 75634286d66SNick Piggin { 757a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7584ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 759a89f8337SAl Viro else 760a89f8337SAl Viro return 1; 76134286d66SNick Piggin } 76234286d66SNick Piggin 7639f1fafeeSAl Viro /** 7649f1fafeeSAl Viro * complete_walk - successful completion of path walk 7659f1fafeeSAl Viro * @nd: pointer nameidata 76639159de2SJeff Layton * 7679f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7689f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7699f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7709f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7719f1fafeeSAl Viro * need to drop nd->path. 77239159de2SJeff Layton */ 7739f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77439159de2SJeff Layton { 77516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77639159de2SJeff Layton int status; 77739159de2SJeff Layton 7789f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7799f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7809f1fafeeSAl Viro nd->root.mnt = NULL; 7814675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 78248a066e7SAl Viro return -ECHILD; 78348a066e7SAl Viro } 7849f1fafeeSAl Viro 78516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78639159de2SJeff Layton return 0; 78739159de2SJeff Layton 788ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 78916c2cd71SAl Viro return 0; 79016c2cd71SAl Viro 791ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79239159de2SJeff Layton if (status > 0) 79339159de2SJeff Layton return 0; 79439159de2SJeff Layton 79516c2cd71SAl Viro if (!status) 79639159de2SJeff Layton status = -ESTALE; 79716c2cd71SAl Viro 79839159de2SJeff Layton return status; 79939159de2SJeff Layton } 80039159de2SJeff Layton 80118d8c860SAl Viro static void set_root(struct nameidata *nd) 8022a737871SAl Viro { 80331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8049e6697e2SAl Viro 8059e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8068f47a016SAl Viro unsigned seq; 807c28cc364SNick Piggin 808c28cc364SNick Piggin do { 809c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81031e6b01fSNick Piggin nd->root = fs->root; 8118f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 812c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8139e6697e2SAl Viro } else { 8149e6697e2SAl Viro get_fs_root(fs, &nd->root); 81584a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8169e6697e2SAl Viro } 81731e6b01fSNick Piggin } 81831e6b01fSNick Piggin 8191d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 820051d3812SIan Kent { 821051d3812SIan Kent dput(path->dentry); 8224ac91378SJan Blunck if (path->mnt != nd->path.mnt) 823051d3812SIan Kent mntput(path->mnt); 824051d3812SIan Kent } 825051d3812SIan Kent 8267b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8277b9337aaSNick Piggin struct nameidata *nd) 828051d3812SIan Kent { 82931e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8304ac91378SJan Blunck dput(nd->path.dentry); 83131e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8324ac91378SJan Blunck mntput(nd->path.mnt); 8339a229683SHuang Shijie } 83431e6b01fSNick Piggin nd->path.mnt = path->mnt; 8354ac91378SJan Blunck nd->path.dentry = path->dentry; 836051d3812SIan Kent } 837051d3812SIan Kent 838248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 839248fb5b9SAl Viro { 840248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 841248fb5b9SAl Viro struct dentry *d; 842248fb5b9SAl Viro nd->path = nd->root; 843248fb5b9SAl Viro d = nd->path.dentry; 844248fb5b9SAl Viro nd->inode = d->d_inode; 845248fb5b9SAl Viro nd->seq = nd->root_seq; 846248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 847248fb5b9SAl Viro return -ECHILD; 848248fb5b9SAl Viro } else { 849248fb5b9SAl Viro path_put(&nd->path); 850248fb5b9SAl Viro nd->path = nd->root; 851248fb5b9SAl Viro path_get(&nd->path); 852248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 853248fb5b9SAl Viro } 854248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 855248fb5b9SAl Viro return 0; 856248fb5b9SAl Viro } 857248fb5b9SAl Viro 858b5fb63c1SChristoph Hellwig /* 8596b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 860b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 861b5fb63c1SChristoph Hellwig */ 8626e77137bSAl Viro void nd_jump_link(struct path *path) 863b5fb63c1SChristoph Hellwig { 8646e77137bSAl Viro struct nameidata *nd = current->nameidata; 865b5fb63c1SChristoph Hellwig path_put(&nd->path); 866b5fb63c1SChristoph Hellwig 867b5fb63c1SChristoph Hellwig nd->path = *path; 868b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 869b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 870b5fb63c1SChristoph Hellwig } 871b5fb63c1SChristoph Hellwig 872b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 873574197e0SAl Viro { 87421c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 875fceef393SAl Viro do_delayed_call(&last->done); 8766548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 877b9ff4429SAl Viro path_put(&last->link); 878574197e0SAl Viro } 879574197e0SAl Viro 880561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 881561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 88230aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 88330aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 884800179c9SKees Cook 885800179c9SKees Cook /** 886800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88755852635SRandy Dunlap * @nd: nameidata pathwalk data 888800179c9SKees Cook * 889800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 890800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 891800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 892800179c9SKees Cook * processes from failing races against path names that may change out 893800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 894800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 895800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 896800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 897800179c9SKees Cook * 898800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 899800179c9SKees Cook */ 900fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 901800179c9SKees Cook { 902800179c9SKees Cook const struct inode *inode; 903800179c9SKees Cook const struct inode *parent; 9042d7f9e2aSSeth Forshee kuid_t puid; 905800179c9SKees Cook 906800179c9SKees Cook if (!sysctl_protected_symlinks) 907800179c9SKees Cook return 0; 908800179c9SKees Cook 909800179c9SKees Cook /* Allowed if owner and follower match. */ 910fceef393SAl Viro inode = nd->link_inode; 91181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 912800179c9SKees Cook return 0; 913800179c9SKees Cook 914800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 915aa65fa35SAl Viro parent = nd->inode; 916800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 917800179c9SKees Cook return 0; 918800179c9SKees Cook 919800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9202d7f9e2aSSeth Forshee puid = parent->i_uid; 9212d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 922800179c9SKees Cook return 0; 923800179c9SKees Cook 92431956502SAl Viro if (nd->flags & LOOKUP_RCU) 92531956502SAl Viro return -ECHILD; 92631956502SAl Viro 927ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 928245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 929800179c9SKees Cook return -EACCES; 930800179c9SKees Cook } 931800179c9SKees Cook 932800179c9SKees Cook /** 933800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 934800179c9SKees Cook * @inode: the source inode to hardlink from 935800179c9SKees Cook * 936800179c9SKees Cook * Return false if at least one of the following conditions: 937800179c9SKees Cook * - inode is not a regular file 938800179c9SKees Cook * - inode is setuid 939800179c9SKees Cook * - inode is setgid and group-exec 940800179c9SKees Cook * - access failure for read and write 941800179c9SKees Cook * 942800179c9SKees Cook * Otherwise returns true. 943800179c9SKees Cook */ 944800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 945800179c9SKees Cook { 946800179c9SKees Cook umode_t mode = inode->i_mode; 947800179c9SKees Cook 948800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 949800179c9SKees Cook if (!S_ISREG(mode)) 950800179c9SKees Cook return false; 951800179c9SKees Cook 952800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 953800179c9SKees Cook if (mode & S_ISUID) 954800179c9SKees Cook return false; 955800179c9SKees Cook 956800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 957800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 958800179c9SKees Cook return false; 959800179c9SKees Cook 960800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 961800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 962800179c9SKees Cook return false; 963800179c9SKees Cook 964800179c9SKees Cook return true; 965800179c9SKees Cook } 966800179c9SKees Cook 967800179c9SKees Cook /** 968800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 969800179c9SKees Cook * @link: the source to hardlink from 970800179c9SKees Cook * 971800179c9SKees Cook * Block hardlink when all of: 972800179c9SKees Cook * - sysctl_protected_hardlinks enabled 973800179c9SKees Cook * - fsuid does not match inode 974800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 975f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 976800179c9SKees Cook * 977800179c9SKees Cook * Returns 0 if successful, -ve on error. 978800179c9SKees Cook */ 979800179c9SKees Cook static int may_linkat(struct path *link) 980800179c9SKees Cook { 981593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 982593d1ce8SEric W. Biederman 983593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 984593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 985593d1ce8SEric W. Biederman return -EOVERFLOW; 986800179c9SKees Cook 987800179c9SKees Cook if (!sysctl_protected_hardlinks) 988800179c9SKees Cook return 0; 989800179c9SKees Cook 990800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 991800179c9SKees Cook * otherwise, it must be a safe source. 992800179c9SKees Cook */ 993cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 994800179c9SKees Cook return 0; 995800179c9SKees Cook 996245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 997800179c9SKees Cook return -EPERM; 998800179c9SKees Cook } 999800179c9SKees Cook 100030aba665SSalvatore Mesoraca /** 100130aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 100230aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 100330aba665SSalvatore Mesoraca * exist. 1004d0cb5018SAl Viro * @dir_mode: mode bits of directory 1005d0cb5018SAl Viro * @dir_uid: owner of directory 100630aba665SSalvatore Mesoraca * @inode: the inode of the file to open 100730aba665SSalvatore Mesoraca * 100830aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 100930aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 101030aba665SSalvatore Mesoraca * - the file already exists 101130aba665SSalvatore Mesoraca * - we are in a sticky directory 101230aba665SSalvatore Mesoraca * - we don't own the file 101330aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 101430aba665SSalvatore Mesoraca * - the directory is world writable 101530aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 101630aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 101730aba665SSalvatore Mesoraca * be enough. 101830aba665SSalvatore Mesoraca * 101930aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 102030aba665SSalvatore Mesoraca */ 1021d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 102230aba665SSalvatore Mesoraca struct inode * const inode) 102330aba665SSalvatore Mesoraca { 102430aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 102530aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1026d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1027d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 102830aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 102930aba665SSalvatore Mesoraca return 0; 103030aba665SSalvatore Mesoraca 1031d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1032d0cb5018SAl Viro (dir_mode & 0020 && 103330aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 103430aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1035245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1036245d7369SKees Cook "sticky_create_fifo" : 1037245d7369SKees Cook "sticky_create_regular"; 1038245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 103930aba665SSalvatore Mesoraca return -EACCES; 104030aba665SSalvatore Mesoraca } 104130aba665SSalvatore Mesoraca return 0; 104230aba665SSalvatore Mesoraca } 104330aba665SSalvatore Mesoraca 10443b2e7f75SAl Viro static __always_inline 10453b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10461da177e4SLinus Torvalds { 1047ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10481cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1049fceef393SAl Viro struct inode *inode = nd->link_inode; 10506d7b5aaeSAl Viro int error; 10510a959df5SAl Viro const char *res; 10521da177e4SLinus Torvalds 10538fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10548fa9dd24SNeilBrown touch_atime(&last->link); 10558fa9dd24SNeilBrown cond_resched(); 1056c6718543SMiklos Szeredi } else if (atime_needs_update(&last->link, inode)) { 10574675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10588fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10598fa9dd24SNeilBrown touch_atime(&last->link); 10608fa9dd24SNeilBrown } 10618fa9dd24SNeilBrown 1062bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1063bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1064bda0be7aSNeilBrown if (unlikely(error)) 10656920a440SAl Viro return ERR_PTR(error); 106636f3b4f6SAl Viro 106786acdca1SAl Viro nd->last_type = LAST_BIND; 10684c4f7c19SEric Biggers res = READ_ONCE(inode->i_link); 1069d4dee48bSAl Viro if (!res) { 1070fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1071fceef393SAl Viro struct delayed_call *); 1072fceef393SAl Viro get = inode->i_op->get_link; 10738c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1074fceef393SAl Viro res = get(NULL, inode, &last->done); 10756b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10764675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10778c1b4566SAl Viro return ERR_PTR(-ECHILD); 1078fceef393SAl Viro res = get(dentry, inode, &last->done); 10798c1b4566SAl Viro } 10806b255391SAl Viro } else { 1081fceef393SAl Viro res = get(dentry, inode, &last->done); 10826b255391SAl Viro } 1083fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1084fab51e8aSAl Viro return res; 10850a959df5SAl Viro } 1086fab51e8aSAl Viro if (*res == '/') { 1087fab51e8aSAl Viro if (!nd->root.mnt) 1088fab51e8aSAl Viro set_root(nd); 1089248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1090fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1091fab51e8aSAl Viro while (unlikely(*++res == '/')) 1092fab51e8aSAl Viro ; 1093fab51e8aSAl Viro } 1094fab51e8aSAl Viro if (!*res) 1095fab51e8aSAl Viro res = NULL; 10960a959df5SAl Viro return res; 10970a959df5SAl Viro } 10986d7b5aaeSAl Viro 1099f015f126SDavid Howells /* 1100f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1101f015f126SDavid Howells * 1102f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1103f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1104f015f126SDavid Howells * Up is towards /. 1105f015f126SDavid Howells * 1106f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1107f015f126SDavid Howells * root. 1108f015f126SDavid Howells */ 1109bab77ebfSAl Viro int follow_up(struct path *path) 11101da177e4SLinus Torvalds { 11110714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11120714a533SAl Viro struct mount *parent; 11131da177e4SLinus Torvalds struct dentry *mountpoint; 111499b7db7bSNick Piggin 111548a066e7SAl Viro read_seqlock_excl(&mount_lock); 11160714a533SAl Viro parent = mnt->mnt_parent; 11173c0a6163SAl Viro if (parent == mnt) { 111848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11191da177e4SLinus Torvalds return 0; 11201da177e4SLinus Torvalds } 11210714a533SAl Viro mntget(&parent->mnt); 1122a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 112348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1124bab77ebfSAl Viro dput(path->dentry); 1125bab77ebfSAl Viro path->dentry = mountpoint; 1126bab77ebfSAl Viro mntput(path->mnt); 11270714a533SAl Viro path->mnt = &parent->mnt; 11281da177e4SLinus Torvalds return 1; 11291da177e4SLinus Torvalds } 11304d359507SAl Viro EXPORT_SYMBOL(follow_up); 11311da177e4SLinus Torvalds 1132b5c84bf6SNick Piggin /* 11339875cf80SDavid Howells * Perform an automount 11349875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11359875cf80SDavid Howells * were called with. 11361da177e4SLinus Torvalds */ 1137756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11389875cf80SDavid Howells bool *need_mntput) 113931e6b01fSNick Piggin { 11409875cf80SDavid Howells struct vfsmount *mnt; 1141ea5b778aSDavid Howells int err; 11429875cf80SDavid Howells 11439875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11449875cf80SDavid Howells return -EREMOTE; 11459875cf80SDavid Howells 11460ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11470ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11480ec26fd0SMiklos Szeredi * the name. 11490ec26fd0SMiklos Szeredi * 11500ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11515a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11520ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11530ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11540ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11550ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11565a30d8a2SDavid Howells */ 1157756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11585d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11595d38f049SIan Kent path->dentry->d_inode) 11609875cf80SDavid Howells return -EISDIR; 11610ec26fd0SMiklos Szeredi 1162756daf26SNeilBrown nd->total_link_count++; 1163756daf26SNeilBrown if (nd->total_link_count >= 40) 11649875cf80SDavid Howells return -ELOOP; 11659875cf80SDavid Howells 11669875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11679875cf80SDavid Howells if (IS_ERR(mnt)) { 11689875cf80SDavid Howells /* 11699875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11709875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11719875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11729875cf80SDavid Howells * 11739875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11749875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11759875cf80SDavid Howells * the path is inaccessible and we should say so. 11769875cf80SDavid Howells */ 1177756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11789875cf80SDavid Howells return -EREMOTE; 11799875cf80SDavid Howells return PTR_ERR(mnt); 118031e6b01fSNick Piggin } 1181ea5b778aSDavid Howells 11829875cf80SDavid Howells if (!mnt) /* mount collision */ 11839875cf80SDavid Howells return 0; 11849875cf80SDavid Howells 11858aef1884SAl Viro if (!*need_mntput) { 11868aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11878aef1884SAl Viro mntget(path->mnt); 11888aef1884SAl Viro *need_mntput = true; 11898aef1884SAl Viro } 119019a167afSAl Viro err = finish_automount(mnt, path); 1191ea5b778aSDavid Howells 1192ea5b778aSDavid Howells switch (err) { 1193ea5b778aSDavid Howells case -EBUSY: 1194ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 119519a167afSAl Viro return 0; 1196ea5b778aSDavid Howells case 0: 11978aef1884SAl Viro path_put(path); 11989875cf80SDavid Howells path->mnt = mnt; 11999875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 12009875cf80SDavid Howells return 0; 120119a167afSAl Viro default: 120219a167afSAl Viro return err; 12039875cf80SDavid Howells } 120419a167afSAl Viro 1205ea5b778aSDavid Howells } 12069875cf80SDavid Howells 12079875cf80SDavid Howells /* 12089875cf80SDavid Howells * Handle a dentry that is managed in some way. 1209cc53ce53SDavid Howells * - Flagged for transit management (autofs) 12109875cf80SDavid Howells * - Flagged as mountpoint 12119875cf80SDavid Howells * - Flagged as automount point 12129875cf80SDavid Howells * 12139875cf80SDavid Howells * This may only be called in refwalk mode. 1214d41efb52SAl Viro * On success path->dentry is known positive. 12159875cf80SDavid Howells * 12169875cf80SDavid Howells * Serialization is taken care of in namespace.c 12179875cf80SDavid Howells */ 1218756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12199875cf80SDavid Howells { 12208aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 1221d41efb52SAl Viro unsigned flags; 12229875cf80SDavid Howells bool need_mntput = false; 12238aef1884SAl Viro int ret = 0; 12249875cf80SDavid Howells 12259875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12269875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 12279875cf80SDavid Howells * the components of that value change under us */ 12282fa6b1e0SAl Viro while (flags = smp_load_acquire(&path->dentry->d_flags), 1229d41efb52SAl Viro unlikely(flags & DCACHE_MANAGED_DENTRY)) { 1230cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1231cc53ce53SDavid Howells * being held. */ 1232d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1233cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1234cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1235fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1236508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1237cc53ce53SDavid Howells if (ret < 0) 12388aef1884SAl Viro break; 1239cc53ce53SDavid Howells } 1240cc53ce53SDavid Howells 12419875cf80SDavid Howells /* Transit to a mounted filesystem. */ 1242d41efb52SAl Viro if (flags & DCACHE_MOUNTED) { 12439875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12449875cf80SDavid Howells if (mounted) { 12459875cf80SDavid Howells dput(path->dentry); 12469875cf80SDavid Howells if (need_mntput) 1247463ffb2eSAl Viro mntput(path->mnt); 1248463ffb2eSAl Viro path->mnt = mounted; 1249463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12509875cf80SDavid Howells need_mntput = true; 12519875cf80SDavid Howells continue; 1252463ffb2eSAl Viro } 1253463ffb2eSAl Viro 12549875cf80SDavid Howells /* Something is mounted on this dentry in another 12559875cf80SDavid Howells * namespace and/or whatever was mounted there in this 125648a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 125748a066e7SAl Viro * get it */ 12581da177e4SLinus Torvalds } 12599875cf80SDavid Howells 12609875cf80SDavid Howells /* Handle an automount point */ 1261d41efb52SAl Viro if (flags & DCACHE_NEED_AUTOMOUNT) { 1262756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12639875cf80SDavid Howells if (ret < 0) 12648aef1884SAl Viro break; 12659875cf80SDavid Howells continue; 12669875cf80SDavid Howells } 12679875cf80SDavid Howells 12689875cf80SDavid Howells /* We didn't change the current path point */ 12699875cf80SDavid Howells break; 12709875cf80SDavid Howells } 12718aef1884SAl Viro 12728aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12738aef1884SAl Viro mntput(path->mnt); 12748402752eSAl Viro if (need_mntput) 12758402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 1276d41efb52SAl Viro if (ret == -EISDIR || !ret) 1277d41efb52SAl Viro ret = 1; 1278d41efb52SAl Viro if (ret > 0 && unlikely(d_flags_negative(flags))) 1279d41efb52SAl Viro ret = -ENOENT; 12808402752eSAl Viro if (unlikely(ret < 0)) 12818402752eSAl Viro path_put_conditional(path, nd); 12828402752eSAl Viro return ret; 12831da177e4SLinus Torvalds } 12841da177e4SLinus Torvalds 1285cc53ce53SDavid Howells int follow_down_one(struct path *path) 12861da177e4SLinus Torvalds { 12871da177e4SLinus Torvalds struct vfsmount *mounted; 12881da177e4SLinus Torvalds 12891c755af4SAl Viro mounted = lookup_mnt(path); 12901da177e4SLinus Torvalds if (mounted) { 12919393bd07SAl Viro dput(path->dentry); 12929393bd07SAl Viro mntput(path->mnt); 12939393bd07SAl Viro path->mnt = mounted; 12949393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12951da177e4SLinus Torvalds return 1; 12961da177e4SLinus Torvalds } 12971da177e4SLinus Torvalds return 0; 12981da177e4SLinus Torvalds } 12994d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 13001da177e4SLinus Torvalds 1301fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 130262a7375eSIan Kent { 1303fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1304fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 130562a7375eSIan Kent } 130662a7375eSIan Kent 13079875cf80SDavid Howells /* 1308287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1309287548e4SAl Viro * we meet a managed dentry that would need blocking. 13109875cf80SDavid Howells */ 13119875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1312254cf582SAl Viro struct inode **inode, unsigned *seqp) 13139875cf80SDavid Howells { 131462a7375eSIan Kent for (;;) { 1315c7105365SAl Viro struct mount *mounted; 131662a7375eSIan Kent /* 131762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 131862a7375eSIan Kent * that wants to block transit. 131962a7375eSIan Kent */ 1320fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1321b8faf035SNeilBrown case -ECHILD: 1322b8faf035SNeilBrown default: 1323ab90911fSDavid Howells return false; 1324b8faf035SNeilBrown case -EISDIR: 1325b8faf035SNeilBrown return true; 1326b8faf035SNeilBrown case 0: 1327b8faf035SNeilBrown break; 1328b8faf035SNeilBrown } 132962a7375eSIan Kent 133062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1331b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 133262a7375eSIan Kent 1333474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13349875cf80SDavid Howells if (!mounted) 13359875cf80SDavid Howells break; 1336c7105365SAl Viro path->mnt = &mounted->mnt; 1337c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1338a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1339254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 134059430262SLinus Torvalds /* 134159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 134259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 134359430262SLinus Torvalds * because a mount-point is always pinned. 134459430262SLinus Torvalds */ 134559430262SLinus Torvalds *inode = path->dentry->d_inode; 13469875cf80SDavid Howells } 1347f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1348b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1349287548e4SAl Viro } 1350287548e4SAl Viro 135131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 135231e6b01fSNick Piggin { 13534023bfc9SAl Viro struct inode *inode = nd->inode; 135431e6b01fSNick Piggin 135531e6b01fSNick Piggin while (1) { 1356aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 135731e6b01fSNick Piggin break; 135831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 135931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 136031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 136131e6b01fSNick Piggin unsigned seq; 136231e6b01fSNick Piggin 13634023bfc9SAl Viro inode = parent->d_inode; 136431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1365aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1366aed434adSAl Viro return -ECHILD; 136731e6b01fSNick Piggin nd->path.dentry = parent; 136831e6b01fSNick Piggin nd->seq = seq; 1369397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1370397d425dSEric W. Biederman return -ENOENT; 137131e6b01fSNick Piggin break; 1372aed434adSAl Viro } else { 1373aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1374aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1375aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1376aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1377aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1378aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1379aed434adSAl Viro return -ECHILD; 1380aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 138131e6b01fSNick Piggin break; 1382aed434adSAl Viro /* we know that mountpoint was pinned */ 1383aed434adSAl Viro nd->path.dentry = mountpoint; 1384aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1385aed434adSAl Viro inode = inode2; 1386aed434adSAl Viro nd->seq = seq; 138731e6b01fSNick Piggin } 1388aed434adSAl Viro } 1389aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1390b37199e6SAl Viro struct mount *mounted; 1391b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1392aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1393aed434adSAl Viro return -ECHILD; 1394b37199e6SAl Viro if (!mounted) 1395b37199e6SAl Viro break; 1396b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1397b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13984023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1399b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1400b37199e6SAl Viro } 14014023bfc9SAl Viro nd->inode = inode; 140231e6b01fSNick Piggin return 0; 140331e6b01fSNick Piggin } 140431e6b01fSNick Piggin 14059875cf80SDavid Howells /* 1406cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1407cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1408cc53ce53SDavid Howells * caller is permitted to proceed or not. 1409cc53ce53SDavid Howells */ 14107cc90cc3SAl Viro int follow_down(struct path *path) 1411cc53ce53SDavid Howells { 1412cc53ce53SDavid Howells unsigned managed; 1413cc53ce53SDavid Howells int ret; 1414cc53ce53SDavid Howells 14156aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1416cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1417cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1418cc53ce53SDavid Howells * being held. 1419cc53ce53SDavid Howells * 1420cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1421cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1422cc53ce53SDavid Howells * other than its daemon the right to mount on its 1423cc53ce53SDavid Howells * superstructure. 1424cc53ce53SDavid Howells * 1425cc53ce53SDavid Howells * The filesystem may sleep at this point. 1426cc53ce53SDavid Howells */ 1427cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1428cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1429cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1430fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1431cc53ce53SDavid Howells if (ret < 0) 1432cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1433cc53ce53SDavid Howells } 1434cc53ce53SDavid Howells 1435cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1436cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1437cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1438cc53ce53SDavid Howells if (!mounted) 1439cc53ce53SDavid Howells break; 1440cc53ce53SDavid Howells dput(path->dentry); 1441cc53ce53SDavid Howells mntput(path->mnt); 1442cc53ce53SDavid Howells path->mnt = mounted; 1443cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1444cc53ce53SDavid Howells continue; 1445cc53ce53SDavid Howells } 1446cc53ce53SDavid Howells 1447cc53ce53SDavid Howells /* Don't handle automount points here */ 1448cc53ce53SDavid Howells break; 1449cc53ce53SDavid Howells } 1450cc53ce53SDavid Howells return 0; 1451cc53ce53SDavid Howells } 14524d359507SAl Viro EXPORT_SYMBOL(follow_down); 1453cc53ce53SDavid Howells 1454cc53ce53SDavid Howells /* 14559875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14569875cf80SDavid Howells */ 14579875cf80SDavid Howells static void follow_mount(struct path *path) 14589875cf80SDavid Howells { 14599875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14609875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14619875cf80SDavid Howells if (!mounted) 14629875cf80SDavid Howells break; 14639875cf80SDavid Howells dput(path->dentry); 14649875cf80SDavid Howells mntput(path->mnt); 14659875cf80SDavid Howells path->mnt = mounted; 14669875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14679875cf80SDavid Howells } 14689875cf80SDavid Howells } 14699875cf80SDavid Howells 1470eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1471eedf265aSEric W. Biederman { 1472eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1473eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1474eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1475eedf265aSEric W. Biederman dput(old); 1476eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1477eedf265aSEric W. Biederman return -ENOENT; 1478eedf265aSEric W. Biederman return 0; 1479eedf265aSEric W. Biederman } 1480eedf265aSEric W. Biederman 1481397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14821da177e4SLinus Torvalds { 14831da177e4SLinus Torvalds while(1) { 1484030c7e0bSDanilo Krummrich if (path_equal(&nd->path, &nd->root)) 14851da177e4SLinus Torvalds break; 14864ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1487eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1488eedf265aSEric W. Biederman if (ret) 1489eedf265aSEric W. Biederman return ret; 14901da177e4SLinus Torvalds break; 14911da177e4SLinus Torvalds } 14923088dd70SAl Viro if (!follow_up(&nd->path)) 14931da177e4SLinus Torvalds break; 14941da177e4SLinus Torvalds } 149579ed0226SAl Viro follow_mount(&nd->path); 149631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1497397d425dSEric W. Biederman return 0; 14981da177e4SLinus Torvalds } 14991da177e4SLinus Torvalds 15001da177e4SLinus Torvalds /* 1501f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1502f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1503baa03890SNick Piggin */ 1504e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1505e3c13928SAl Viro struct dentry *dir, 15066c51e513SAl Viro unsigned int flags) 1507baa03890SNick Piggin { 1508a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1509bad61189SMiklos Szeredi if (dentry) { 1510a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1511bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 151274ff0ffcSAl Viro if (!error) 15135542aa2fSEric W. Biederman d_invalidate(dentry); 1514bad61189SMiklos Szeredi dput(dentry); 151574ff0ffcSAl Viro return ERR_PTR(error); 1516bad61189SMiklos Szeredi } 1517bad61189SMiklos Szeredi } 1518baa03890SNick Piggin return dentry; 1519baa03890SNick Piggin } 1520baa03890SNick Piggin 1521baa03890SNick Piggin /* 1522a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1523a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1524a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1525a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1526a03ece5fSAl Viro * at all. 152744396f4bSJosef Bacik */ 1528a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1529a03ece5fSAl Viro struct dentry *base, unsigned int flags) 153044396f4bSJosef Bacik { 1531a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 153244396f4bSJosef Bacik struct dentry *old; 1533a03ece5fSAl Viro struct inode *dir = base->d_inode; 1534a03ece5fSAl Viro 1535a03ece5fSAl Viro if (dentry) 1536a03ece5fSAl Viro return dentry; 153744396f4bSJosef Bacik 153844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1539a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 154044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1541a03ece5fSAl Viro 1542a03ece5fSAl Viro dentry = d_alloc(base, name); 1543a03ece5fSAl Viro if (unlikely(!dentry)) 1544a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 154544396f4bSJosef Bacik 154672bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 154744396f4bSJosef Bacik if (unlikely(old)) { 154844396f4bSJosef Bacik dput(dentry); 154944396f4bSJosef Bacik dentry = old; 155044396f4bSJosef Bacik } 155144396f4bSJosef Bacik return dentry; 155244396f4bSJosef Bacik } 155344396f4bSJosef Bacik 1554e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1555254cf582SAl Viro struct path *path, struct inode **inode, 1556254cf582SAl Viro unsigned *seqp) 15571da177e4SLinus Torvalds { 15584ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 155931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15605a18fff2SAl Viro int status = 1; 15619875cf80SDavid Howells int err; 15629875cf80SDavid Howells 15633cac260aSAl Viro /* 1564b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15655d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15665d0f49c1SAl Viro * going to fall back to non-racy lookup. 1567b04f784eSNick Piggin */ 156831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 156931e6b01fSNick Piggin unsigned seq; 1570766c4cbfSAl Viro bool negative; 1571da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15725d0f49c1SAl Viro if (unlikely(!dentry)) { 15734675ac39SAl Viro if (unlazy_walk(nd)) 15745d0f49c1SAl Viro return -ECHILD; 1575e9742b53SAl Viro return 0; 15765d0f49c1SAl Viro } 15775a18fff2SAl Viro 157812f8ad4bSLinus Torvalds /* 157912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 158012f8ad4bSLinus Torvalds * the dentry name information from lookup. 158112f8ad4bSLinus Torvalds */ 158263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1583766c4cbfSAl Viro negative = d_is_negative(dentry); 15845d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 158512f8ad4bSLinus Torvalds return -ECHILD; 158612f8ad4bSLinus Torvalds 158712f8ad4bSLinus Torvalds /* 158812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 158912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 159012f8ad4bSLinus Torvalds * 159112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 159212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 159312f8ad4bSLinus Torvalds */ 15945d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 159531e6b01fSNick Piggin return -ECHILD; 15965a18fff2SAl Viro 1597254cf582SAl Viro *seqp = seq; 15984ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1599209a7fb2SAl Viro if (likely(status > 0)) { 1600daf3761cSTrond Myklebust /* 1601daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1602daf3761cSTrond Myklebust * case that drops it. 1603daf3761cSTrond Myklebust */ 16045d0f49c1SAl Viro if (unlikely(negative)) 1605daf3761cSTrond Myklebust return -ENOENT; 160631e6b01fSNick Piggin path->mnt = mnt; 160731e6b01fSNick Piggin path->dentry = dentry; 1608254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1609e9742b53SAl Viro return 1; 16105d0f49c1SAl Viro } 16114675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1612254cf582SAl Viro return -ECHILD; 1613209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1614209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1615209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16165a18fff2SAl Viro } else { 1617e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 161881e6f520SAl Viro if (unlikely(!dentry)) 1619e9742b53SAl Viro return 0; 16204ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16215d0f49c1SAl Viro } 16225a18fff2SAl Viro if (unlikely(status <= 0)) { 1623e9742b53SAl Viro if (!status) 16245d0f49c1SAl Viro d_invalidate(dentry); 16255a18fff2SAl Viro dput(dentry); 16265a18fff2SAl Viro return status; 16275a18fff2SAl Viro } 16285d0f49c1SAl Viro 16291da177e4SLinus Torvalds path->mnt = mnt; 16301da177e4SLinus Torvalds path->dentry = dentry; 1631756daf26SNeilBrown err = follow_managed(path, nd); 1632e9742b53SAl Viro if (likely(err > 0)) 163363afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16348402752eSAl Viro return err; 1635697f514dSMiklos Szeredi } 1636697f514dSMiklos Szeredi 1637697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 163888d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1639e3c13928SAl Viro struct dentry *dir, 1640e3c13928SAl Viro unsigned int flags) 1641697f514dSMiklos Szeredi { 164288d8331aSAl Viro struct dentry *dentry, *old; 16431936386eSAl Viro struct inode *inode = dir->d_inode; 1644d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16451936386eSAl Viro 16461936386eSAl Viro /* Don't go there if it's already dead */ 164794bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 164888d8331aSAl Viro return ERR_PTR(-ENOENT); 164994bdd655SAl Viro again: 1650d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 165194bdd655SAl Viro if (IS_ERR(dentry)) 165288d8331aSAl Viro return dentry; 165394bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1654949a852eSAl Viro int error = d_revalidate(dentry, flags); 1655949a852eSAl Viro if (unlikely(error <= 0)) { 165694bdd655SAl Viro if (!error) { 1657949a852eSAl Viro d_invalidate(dentry); 1658949a852eSAl Viro dput(dentry); 165994bdd655SAl Viro goto again; 166094bdd655SAl Viro } 166194bdd655SAl Viro dput(dentry); 1662949a852eSAl Viro dentry = ERR_PTR(error); 1663949a852eSAl Viro } 166494bdd655SAl Viro } else { 16651936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 166685c7f810SAl Viro d_lookup_done(dentry); 16671936386eSAl Viro if (unlikely(old)) { 16681936386eSAl Viro dput(dentry); 16691936386eSAl Viro dentry = old; 1670949a852eSAl Viro } 1671949a852eSAl Viro } 1672e3c13928SAl Viro return dentry; 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds 167588d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 167688d8331aSAl Viro struct dentry *dir, 167788d8331aSAl Viro unsigned int flags) 167888d8331aSAl Viro { 167988d8331aSAl Viro struct inode *inode = dir->d_inode; 168088d8331aSAl Viro struct dentry *res; 168188d8331aSAl Viro inode_lock_shared(inode); 168288d8331aSAl Viro res = __lookup_slow(name, dir, flags); 168388d8331aSAl Viro inode_unlock_shared(inode); 168488d8331aSAl Viro return res; 168588d8331aSAl Viro } 168688d8331aSAl Viro 168752094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 168852094c8aSAl Viro { 168952094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16904ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 169152094c8aSAl Viro if (err != -ECHILD) 169252094c8aSAl Viro return err; 16934675ac39SAl Viro if (unlazy_walk(nd)) 169452094c8aSAl Viro return -ECHILD; 169552094c8aSAl Viro } 16964ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 169752094c8aSAl Viro } 169852094c8aSAl Viro 16999856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 17009856fa1bSAl Viro { 17019856fa1bSAl Viro if (type == LAST_DOTDOT) { 17029e6697e2SAl Viro if (!nd->root.mnt) 17039e6697e2SAl Viro set_root(nd); 17049856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 170570291aecSAl Viro return follow_dotdot_rcu(nd); 17069856fa1bSAl Viro } else 1707397d425dSEric W. Biederman return follow_dotdot(nd); 17089856fa1bSAl Viro } 17099856fa1bSAl Viro return 0; 17109856fa1bSAl Viro } 17119856fa1bSAl Viro 1712181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1713181548c0SAl Viro struct inode *inode, unsigned seq) 1714d63ff28fSAl Viro { 1715626de996SAl Viro int error; 17161cf2665bSAl Viro struct saved *last; 1717756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1718626de996SAl Viro path_to_nameidata(link, nd); 1719626de996SAl Viro return -ELOOP; 1720626de996SAl Viro } 1721bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1722cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1723cd179f44SAl Viro mntget(link->mnt); 17247973387aSAl Viro } 1725626de996SAl Viro error = nd_alloc_stack(nd); 1726626de996SAl Viro if (unlikely(error)) { 1727bc40aee0SAl Viro if (error == -ECHILD) { 1728ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1729ad1633a1SAl Viro drop_links(nd); 1730ad1633a1SAl Viro nd->depth = 0; 1731ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1732ad1633a1SAl Viro nd->path.mnt = NULL; 1733ad1633a1SAl Viro nd->path.dentry = NULL; 1734ad1633a1SAl Viro rcu_read_unlock(); 17354675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1736bc40aee0SAl Viro error = nd_alloc_stack(nd); 1737bc40aee0SAl Viro } 1738bc40aee0SAl Viro if (error) { 1739cd179f44SAl Viro path_put(link); 1740626de996SAl Viro return error; 1741626de996SAl Viro } 1742bc40aee0SAl Viro } 1743626de996SAl Viro 1744ab104923SAl Viro last = nd->stack + nd->depth++; 17451cf2665bSAl Viro last->link = *link; 1746fceef393SAl Viro clear_delayed_call(&last->done); 1747fceef393SAl Viro nd->link_inode = inode; 17480450b2d1SAl Viro last->seq = seq; 1749d63ff28fSAl Viro return 1; 1750d63ff28fSAl Viro } 1751d63ff28fSAl Viro 17528f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 175331d66bcdSAl Viro 17543ddcd056SLinus Torvalds /* 17553ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17563ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17573ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17583ddcd056SLinus Torvalds * for the common case. 17593ddcd056SLinus Torvalds */ 17608f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17618f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17623ddcd056SLinus Torvalds { 176331d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 176431d66bcdSAl Viro put_link(nd); 17658f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17668f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17678f64fb1cSAl Viro /* not a symlink or should not follow */ 17688f64fb1cSAl Viro path_to_nameidata(path, nd); 17698f64fb1cSAl Viro nd->inode = inode; 17708f64fb1cSAl Viro nd->seq = seq; 1771d63ff28fSAl Viro return 0; 17728f64fb1cSAl Viro } 1773a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1774a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17758f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1776a7f77542SAl Viro return -ECHILD; 1777a7f77542SAl Viro } 17788f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17793ddcd056SLinus Torvalds } 17803ddcd056SLinus Torvalds 17814693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1782ce57dfc1SAl Viro { 1783caa85634SAl Viro struct path path; 1784ce57dfc1SAl Viro struct inode *inode; 1785254cf582SAl Viro unsigned seq; 1786ce57dfc1SAl Viro int err; 1787ce57dfc1SAl Viro /* 1788ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1789ce57dfc1SAl Viro * to be able to know about the current root directory and 1790ce57dfc1SAl Viro * parent relationships. 1791ce57dfc1SAl Viro */ 17924693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17934693a547SAl Viro err = handle_dots(nd, nd->last_type); 17941c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17954693a547SAl Viro put_link(nd); 17964693a547SAl Viro return err; 17974693a547SAl Viro } 1798254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1799e9742b53SAl Viro if (unlikely(err <= 0)) { 1800697f514dSMiklos Szeredi if (err < 0) 1801f0a9ba70SAl Viro return err; 1802e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1803e3c13928SAl Viro nd->flags); 1804e3c13928SAl Viro if (IS_ERR(path.dentry)) 1805e3c13928SAl Viro return PTR_ERR(path.dentry); 18067500c38aSAl Viro 1807e3c13928SAl Viro path.mnt = nd->path.mnt; 1808e3c13928SAl Viro err = follow_managed(&path, nd); 1809e3c13928SAl Viro if (unlikely(err < 0)) 1810f0a9ba70SAl Viro return err; 1811697f514dSMiklos Szeredi 1812254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1813d4565649SAl Viro inode = d_backing_inode(path.dentry); 1814766c4cbfSAl Viro } 1815697f514dSMiklos Szeredi 18168f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1817ce57dfc1SAl Viro } 1818ce57dfc1SAl Viro 18191da177e4SLinus Torvalds /* 1820bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1821bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1822bfcfaa77SLinus Torvalds * 1823bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1824bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1825bfcfaa77SLinus Torvalds * fast. 1826bfcfaa77SLinus Torvalds * 1827bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1828bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1829bfcfaa77SLinus Torvalds * crossing operation. 1830bfcfaa77SLinus Torvalds * 1831bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1832bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1833bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1834bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1835bfcfaa77SLinus Torvalds */ 1836bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1837bfcfaa77SLinus Torvalds 1838f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1839bfcfaa77SLinus Torvalds 1840468a9428SGeorge Spelvin #ifdef HASH_MIX 1841bfcfaa77SLinus Torvalds 1842468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1843468a9428SGeorge Spelvin 1844468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18452a18da7aSGeorge Spelvin /* 18462a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18472a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18482a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18492a18da7aSGeorge Spelvin * and no temporaries. 18502a18da7aSGeorge Spelvin * 18512a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18522a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18532a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18542a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18552a18da7aSGeorge Spelvin * 18562a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18572a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18582a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18592a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18602a18da7aSGeorge Spelvin * 18612a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18622a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18632a18da7aSGeorge Spelvin * toggling any given output bit. 18642a18da7aSGeorge Spelvin * 18652a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18662a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18672a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18682a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18692a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18702a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18712a18da7aSGeorge Spelvin * Perfect: 8192 258048 18722a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18732a18da7aSGeorge Spelvin */ 18742a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18752a18da7aSGeorge Spelvin ( x ^= (a), \ 18762a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18772a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18782a18da7aSGeorge Spelvin y *= 9 ) 1879bfcfaa77SLinus Torvalds 18800fed3ac8SGeorge Spelvin /* 18812a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18822a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18832a18da7aSGeorge Spelvin * work done before the hash value is used. 18840fed3ac8SGeorge Spelvin */ 18852a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18860fed3ac8SGeorge Spelvin { 18872a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18882a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18892a18da7aSGeorge Spelvin return y >> 32; 18900fed3ac8SGeorge Spelvin } 18910fed3ac8SGeorge Spelvin 1892bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1893bfcfaa77SLinus Torvalds 18942a18da7aSGeorge Spelvin /* 18952a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18962a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18972a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18982a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18992a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19002a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19012a18da7aSGeorge Spelvin * Perfect: 2048 31744 19022a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19032a18da7aSGeorge Spelvin */ 19042a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19052a18da7aSGeorge Spelvin ( x ^= (a), \ 19062a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19072a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19082a18da7aSGeorge Spelvin y *= 9 ) 1909bfcfaa77SLinus Torvalds 19102a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19110fed3ac8SGeorge Spelvin { 19122a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19132a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19140fed3ac8SGeorge Spelvin } 19150fed3ac8SGeorge Spelvin 1916bfcfaa77SLinus Torvalds #endif 1917bfcfaa77SLinus Torvalds 19182a18da7aSGeorge Spelvin /* 19192a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19202a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19212a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19222a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19232a18da7aSGeorge Spelvin * finds the delimiter after the name. 19242a18da7aSGeorge Spelvin */ 19258387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1926bfcfaa77SLinus Torvalds { 19278387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1928bfcfaa77SLinus Torvalds 1929bfcfaa77SLinus Torvalds for (;;) { 1930fcfd2fbfSGeorge Spelvin if (!len) 1931fcfd2fbfSGeorge Spelvin goto done; 1932e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1933bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1934bfcfaa77SLinus Torvalds break; 19352a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1936bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1937bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1938bfcfaa77SLinus Torvalds } 19392a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1940bfcfaa77SLinus Torvalds done: 19412a18da7aSGeorge Spelvin return fold_hash(x, y); 1942bfcfaa77SLinus Torvalds } 1943bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1944bfcfaa77SLinus Torvalds 1945fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19468387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1947fcfd2fbfSGeorge Spelvin { 19488387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19498387ff25SLinus Torvalds unsigned long adata, mask, len; 1950fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1951fcfd2fbfSGeorge Spelvin 19528387ff25SLinus Torvalds len = 0; 19538387ff25SLinus Torvalds goto inside; 19548387ff25SLinus Torvalds 1955fcfd2fbfSGeorge Spelvin do { 19562a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1957fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19588387ff25SLinus Torvalds inside: 1959fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1960fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1961fcfd2fbfSGeorge Spelvin 1962fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1963fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19642a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1965fcfd2fbfSGeorge Spelvin 19662a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1967fcfd2fbfSGeorge Spelvin } 1968fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1969fcfd2fbfSGeorge Spelvin 1970bfcfaa77SLinus Torvalds /* 1971bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1972d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1973bfcfaa77SLinus Torvalds */ 19748387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1975bfcfaa77SLinus Torvalds { 19768387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19778387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 197836126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1979bfcfaa77SLinus Torvalds 19808387ff25SLinus Torvalds len = 0; 19818387ff25SLinus Torvalds goto inside; 19828387ff25SLinus Torvalds 1983bfcfaa77SLinus Torvalds do { 19842a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1985bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19868387ff25SLinus Torvalds inside: 1987e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 198836126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 198936126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1990bfcfaa77SLinus Torvalds 199136126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 199236126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 199336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19942a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 199536126f8fSLinus Torvalds 19962a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1997bfcfaa77SLinus Torvalds } 1998bfcfaa77SLinus Torvalds 19992a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2000bfcfaa77SLinus Torvalds 2001fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20028387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20030145acc2SLinus Torvalds { 20048387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20050145acc2SLinus Torvalds while (len--) 2006fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20070145acc2SLinus Torvalds return end_name_hash(hash); 20080145acc2SLinus Torvalds } 2009ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20100145acc2SLinus Torvalds 2011fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20128387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2013fcfd2fbfSGeorge Spelvin { 20148387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2015fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2016fcfd2fbfSGeorge Spelvin 2017fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2018e0ab7af9SGeorge Spelvin while (c) { 2019fcfd2fbfSGeorge Spelvin len++; 2020fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2021fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2022e0ab7af9SGeorge Spelvin } 2023fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2024fcfd2fbfSGeorge Spelvin } 2025f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2026fcfd2fbfSGeorge Spelvin 20273ddcd056SLinus Torvalds /* 2028200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2029200e9ef7SLinus Torvalds * one character. 2030200e9ef7SLinus Torvalds */ 20318387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2032200e9ef7SLinus Torvalds { 20338387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2034200e9ef7SLinus Torvalds unsigned long len = 0, c; 2035200e9ef7SLinus Torvalds 2036200e9ef7SLinus Torvalds c = (unsigned char)*name; 2037200e9ef7SLinus Torvalds do { 2038200e9ef7SLinus Torvalds len++; 2039200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2040200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2041200e9ef7SLinus Torvalds } while (c && c != '/'); 2042d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2043200e9ef7SLinus Torvalds } 2044200e9ef7SLinus Torvalds 2045bfcfaa77SLinus Torvalds #endif 2046bfcfaa77SLinus Torvalds 2047200e9ef7SLinus Torvalds /* 20481da177e4SLinus Torvalds * Name resolution. 2049ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2050ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20511da177e4SLinus Torvalds * 2052ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2053ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20541da177e4SLinus Torvalds */ 20556de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20561da177e4SLinus Torvalds { 20571da177e4SLinus Torvalds int err; 20581da177e4SLinus Torvalds 20599b5858e9SAl Viro if (IS_ERR(name)) 20609b5858e9SAl Viro return PTR_ERR(name); 20611da177e4SLinus Torvalds while (*name=='/') 20621da177e4SLinus Torvalds name++; 20631da177e4SLinus Torvalds if (!*name) 20649e18f10aSAl Viro return 0; 20651da177e4SLinus Torvalds 20661da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20671da177e4SLinus Torvalds for(;;) { 2068d6bb3e90SLinus Torvalds u64 hash_len; 2069fe479a58SAl Viro int type; 20701da177e4SLinus Torvalds 207152094c8aSAl Viro err = may_lookup(nd); 20721da177e4SLinus Torvalds if (err) 20733595e234SAl Viro return err; 20741da177e4SLinus Torvalds 20758387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20761da177e4SLinus Torvalds 2077fe479a58SAl Viro type = LAST_NORM; 2078d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2079fe479a58SAl Viro case 2: 2080200e9ef7SLinus Torvalds if (name[1] == '.') { 2081fe479a58SAl Viro type = LAST_DOTDOT; 208216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 208316c2cd71SAl Viro } 2084fe479a58SAl Viro break; 2085fe479a58SAl Viro case 1: 2086fe479a58SAl Viro type = LAST_DOT; 2087fe479a58SAl Viro } 20885a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20895a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 209016c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20915a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2092a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2093da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20945a202bcdSAl Viro if (err < 0) 20953595e234SAl Viro return err; 2096d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2097d6bb3e90SLinus Torvalds name = this.name; 20985a202bcdSAl Viro } 20995a202bcdSAl Viro } 2100fe479a58SAl Viro 2101d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2102d6bb3e90SLinus Torvalds nd->last.name = name; 21035f4a6a69SAl Viro nd->last_type = type; 21045f4a6a69SAl Viro 2105d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2106d6bb3e90SLinus Torvalds if (!*name) 2107bdf6cbf1SAl Viro goto OK; 2108200e9ef7SLinus Torvalds /* 2109200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2110200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2111200e9ef7SLinus Torvalds */ 2112200e9ef7SLinus Torvalds do { 2113d6bb3e90SLinus Torvalds name++; 2114d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21158620c238SAl Viro if (unlikely(!*name)) { 21168620c238SAl Viro OK: 2117368ee9baSAl Viro /* pathname body, done */ 21188620c238SAl Viro if (!nd->depth) 21198620c238SAl Viro return 0; 21208620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2121368ee9baSAl Viro /* trailing symlink, done */ 21228620c238SAl Viro if (!name) 21238620c238SAl Viro return 0; 21248620c238SAl Viro /* last component of nested symlink */ 21258f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 21261c4ff1a8SAl Viro } else { 21271c4ff1a8SAl Viro /* not the last component */ 21288f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 21298620c238SAl Viro } 2130ce57dfc1SAl Viro if (err < 0) 21313595e234SAl Viro return err; 2132fe479a58SAl Viro 2133ce57dfc1SAl Viro if (err) { 2134626de996SAl Viro const char *s = get_link(nd); 21355a460275SAl Viro 2136a1c83681SViresh Kumar if (IS_ERR(s)) 21373595e234SAl Viro return PTR_ERR(s); 2138172a39a0SAl Viro err = 0; 213912b09578SAl Viro if (unlikely(!s)) { 214012b09578SAl Viro /* jumped */ 2141b9ff4429SAl Viro put_link(nd); 214212b09578SAl Viro } else { 2143071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 214432cd7468SAl Viro name = s; 21459e18f10aSAl Viro continue; 214648c8b0c5SAl Viro } 214731e6b01fSNick Piggin } 214897242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 214997242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21504675ac39SAl Viro if (unlazy_walk(nd)) 215197242f99SAl Viro return -ECHILD; 215297242f99SAl Viro } 21533595e234SAl Viro return -ENOTDIR; 21545f4a6a69SAl Viro } 2155ce57dfc1SAl Viro } 215697242f99SAl Viro } 21571da177e4SLinus Torvalds 2158edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2159c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 216031e6b01fSNick Piggin { 2161c8a53ee5SAl Viro const char *s = nd->name->name; 216231e6b01fSNick Piggin 2163c0eb027eSLinus Torvalds if (!*s) 2164c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2165edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2166edc2b1daSAl Viro rcu_read_lock(); 2167c0eb027eSLinus Torvalds 216831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2169980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 217031e6b01fSNick Piggin nd->depth = 0; 21715b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2172b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2173b18825a7SDavid Howells struct inode *inode = root->d_inode; 217493893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2175368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21765b6ca027SAl Viro nd->path = nd->root; 21775b6ca027SAl Viro nd->inode = inode; 21785b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21795b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21808f47a016SAl Viro nd->root_seq = nd->seq; 218148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21825b6ca027SAl Viro } else { 21835b6ca027SAl Viro path_get(&nd->path); 21845b6ca027SAl Viro } 2185368ee9baSAl Viro return s; 21865b6ca027SAl Viro } 21875b6ca027SAl Viro 218831e6b01fSNick Piggin nd->root.mnt = NULL; 2189248fb5b9SAl Viro nd->path.mnt = NULL; 2190248fb5b9SAl Viro nd->path.dentry = NULL; 219131e6b01fSNick Piggin 219248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2193fd2f7cb5SAl Viro if (*s == '/') { 2194e41f7d4eSAl Viro set_root(nd); 2195248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2196ef55d917SAl Viro return s; 2197ef55d917SAl Viro return ERR_PTR(-ECHILD); 2198c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2199e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 220031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2201c28cc364SNick Piggin unsigned seq; 220231e6b01fSNick Piggin 2203c28cc364SNick Piggin do { 2204c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 220531e6b01fSNick Piggin nd->path = fs->pwd; 2206ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2207c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2208c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2209e41f7d4eSAl Viro } else { 2210e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2211ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2212e41f7d4eSAl Viro } 2213ef55d917SAl Viro return s; 221431e6b01fSNick Piggin } else { 2215582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2216c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 221731e6b01fSNick Piggin struct dentry *dentry; 221831e6b01fSNick Piggin 22192903ff01SAl Viro if (!f.file) 2220368ee9baSAl Viro return ERR_PTR(-EBADF); 222131e6b01fSNick Piggin 22222903ff01SAl Viro dentry = f.file->f_path.dentry; 222331e6b01fSNick Piggin 2224edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22252903ff01SAl Viro fdput(f); 2226368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2227f52e0c11SAl Viro } 22282903ff01SAl Viro 22292903ff01SAl Viro nd->path = f.file->f_path; 2230e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 223134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 223234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22335590ff0dSUlrich Drepper } else { 22342903ff01SAl Viro path_get(&nd->path); 223534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22361da177e4SLinus Torvalds } 223734a26b99SAl Viro fdput(f); 2238368ee9baSAl Viro return s; 2239e41f7d4eSAl Viro } 22409b4a9b14SAl Viro } 22419b4a9b14SAl Viro 22423bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 224395fa25d9SAl Viro { 224495fa25d9SAl Viro const char *s; 2245fec2fa24SAl Viro int error = may_follow_link(nd); 2246deb106c6SAl Viro if (unlikely(error)) 22473bdba28bSAl Viro return ERR_PTR(error); 224895fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2249fab51e8aSAl Viro nd->stack[0].name = NULL; 22503b2e7f75SAl Viro s = get_link(nd); 2251deb106c6SAl Viro return s ? s : ""; 225295fa25d9SAl Viro } 225395fa25d9SAl Viro 2254caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2255bd92d7feSAl Viro { 2256bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2257bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2258bd92d7feSAl Viro 2259bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22601c4ff1a8SAl Viro return walk_component(nd, 0); 2261bd92d7feSAl Viro } 2262bd92d7feSAl Viro 22634f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22644f757f3cSAl Viro { 22654f757f3cSAl Viro struct path path = nd->path; 22664f757f3cSAl Viro struct inode *inode = nd->inode; 22674f757f3cSAl Viro unsigned seq = nd->seq; 22684f757f3cSAl Viro int err; 22694f757f3cSAl Viro 22704f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22714f757f3cSAl Viro /* 22724f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22734f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22744f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22754f757f3cSAl Viro */ 22764f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22774f757f3cSAl Viro return -ECHILD; 22784f757f3cSAl Viro } else { 22794f757f3cSAl Viro dget(path.dentry); 22804f757f3cSAl Viro err = follow_managed(&path, nd); 22814f757f3cSAl Viro if (unlikely(err < 0)) 22824f757f3cSAl Viro return err; 22834f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22844f757f3cSAl Viro seq = 0; 22854f757f3cSAl Viro } 22864f757f3cSAl Viro path_to_nameidata(&path, nd); 22874f757f3cSAl Viro nd->inode = inode; 22884f757f3cSAl Viro nd->seq = seq; 22894f757f3cSAl Viro return 0; 22904f757f3cSAl Viro } 22914f757f3cSAl Viro 22929b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2293c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22949b4a9b14SAl Viro { 2295c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2296bd92d7feSAl Viro int err; 229731e6b01fSNick Piggin 22989b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 22994f757f3cSAl Viro err = handle_lookup_down(nd); 23005f336e72SAl Viro if (unlikely(err < 0)) 23015f336e72SAl Viro s = ERR_PTR(err); 23024f757f3cSAl Viro } 23034f757f3cSAl Viro 23043bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 23053bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 23063bdba28bSAl Viro s = trailing_symlink(nd); 2307bd92d7feSAl Viro } 23089f1fafeeSAl Viro if (!err) 23099f1fafeeSAl Viro err = complete_walk(nd); 2310bd92d7feSAl Viro 2311deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2312deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2313bd23a539SAl Viro err = -ENOTDIR; 2314625b6d10SAl Viro if (!err) { 2315625b6d10SAl Viro *path = nd->path; 2316625b6d10SAl Viro nd->path.mnt = NULL; 2317625b6d10SAl Viro nd->path.dentry = NULL; 2318625b6d10SAl Viro } 2319deb106c6SAl Viro terminate_walk(nd); 2320bd92d7feSAl Viro return err; 232131e6b01fSNick Piggin } 232231e6b01fSNick Piggin 232331d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23249ad1aaa6SAl Viro struct path *path, struct path *root) 2325873f1eedSJeff Layton { 2326894bc8c4SAl Viro int retval; 23279883d185SAl Viro struct nameidata nd; 2328abc9f5beSAl Viro if (IS_ERR(name)) 2329abc9f5beSAl Viro return PTR_ERR(name); 23309ad1aaa6SAl Viro if (unlikely(root)) { 23319ad1aaa6SAl Viro nd.root = *root; 23329ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23339ad1aaa6SAl Viro } 23349883d185SAl Viro set_nameidata(&nd, dfd, name); 2335c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2336873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2337c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2338873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2339c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2340873f1eedSJeff Layton 2341873f1eedSJeff Layton if (likely(!retval)) 2342ff0ebee2SAl Viro audit_inode(name, path->dentry, 0); 23439883d185SAl Viro restore_nameidata(); 2344e4bd1c1aSAl Viro putname(name); 2345873f1eedSJeff Layton return retval; 2346873f1eedSJeff Layton } 2347873f1eedSJeff Layton 23488bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2349c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2350391172c4SAl Viro struct path *parent) 23518bcb77faSAl Viro { 2352c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23539b5858e9SAl Viro int err = link_path_walk(s, nd); 23548bcb77faSAl Viro if (!err) 23558bcb77faSAl Viro err = complete_walk(nd); 2356391172c4SAl Viro if (!err) { 2357391172c4SAl Viro *parent = nd->path; 2358391172c4SAl Viro nd->path.mnt = NULL; 2359391172c4SAl Viro nd->path.dentry = NULL; 2360391172c4SAl Viro } 2361deb106c6SAl Viro terminate_walk(nd); 23628bcb77faSAl Viro return err; 23638bcb77faSAl Viro } 23648bcb77faSAl Viro 23655c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2366391172c4SAl Viro unsigned int flags, struct path *parent, 2367391172c4SAl Viro struct qstr *last, int *type) 23688bcb77faSAl Viro { 23698bcb77faSAl Viro int retval; 23709883d185SAl Viro struct nameidata nd; 23718bcb77faSAl Viro 23725c31b6ceSAl Viro if (IS_ERR(name)) 23735c31b6ceSAl Viro return name; 23749883d185SAl Viro set_nameidata(&nd, dfd, name); 2375c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23768bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2377c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23788bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2379c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2380391172c4SAl Viro if (likely(!retval)) { 2381391172c4SAl Viro *last = nd.last; 2382391172c4SAl Viro *type = nd.last_type; 2383c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 23845c31b6ceSAl Viro } else { 23855c31b6ceSAl Viro putname(name); 23865c31b6ceSAl Viro name = ERR_PTR(retval); 2387391172c4SAl Viro } 23889883d185SAl Viro restore_nameidata(); 23895c31b6ceSAl Viro return name; 23908bcb77faSAl Viro } 23918bcb77faSAl Viro 239279714f72SAl Viro /* does lookup, returns the object with parent locked */ 239379714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23945590ff0dSUlrich Drepper { 23955c31b6ceSAl Viro struct filename *filename; 23965c31b6ceSAl Viro struct dentry *d; 2397391172c4SAl Viro struct qstr last; 2398391172c4SAl Viro int type; 239951689104SPaul Moore 24005c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24015c31b6ceSAl Viro &last, &type); 240251689104SPaul Moore if (IS_ERR(filename)) 240351689104SPaul Moore return ERR_CAST(filename); 24045c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2405391172c4SAl Viro path_put(path); 24065c31b6ceSAl Viro putname(filename); 24075c31b6ceSAl Viro return ERR_PTR(-EINVAL); 240879714f72SAl Viro } 24095955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2410391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 241179714f72SAl Viro if (IS_ERR(d)) { 24125955102cSAl Viro inode_unlock(path->dentry->d_inode); 2413391172c4SAl Viro path_put(path); 241479714f72SAl Viro } 241551689104SPaul Moore putname(filename); 241679714f72SAl Viro return d; 24175590ff0dSUlrich Drepper } 24185590ff0dSUlrich Drepper 2419d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2420d1811465SAl Viro { 2421abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2422abc9f5beSAl Viro flags, path, NULL); 2423d1811465SAl Viro } 24244d359507SAl Viro EXPORT_SYMBOL(kern_path); 2425d1811465SAl Viro 242616f18200SJosef 'Jeff' Sipek /** 242716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 242816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 242916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 243016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 243116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2432e0a01249SAl Viro * @path: pointer to struct path to fill 243316f18200SJosef 'Jeff' Sipek */ 243416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 243516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2436e0a01249SAl Viro struct path *path) 243716f18200SJosef 'Jeff' Sipek { 24389ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24399ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2440abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2441abc9f5beSAl Viro flags , path, &root); 244216f18200SJosef 'Jeff' Sipek } 24434d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 244416f18200SJosef 'Jeff' Sipek 24453c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24463c95f0dcSAl Viro int len, struct qstr *this) 24473c95f0dcSAl Viro { 24483c95f0dcSAl Viro this->name = name; 24493c95f0dcSAl Viro this->len = len; 24503c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24513c95f0dcSAl Viro if (!len) 24523c95f0dcSAl Viro return -EACCES; 24533c95f0dcSAl Viro 24543c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24553c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24563c95f0dcSAl Viro return -EACCES; 24573c95f0dcSAl Viro } 24583c95f0dcSAl Viro 24593c95f0dcSAl Viro while (len--) { 24603c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24613c95f0dcSAl Viro if (c == '/' || c == '\0') 24623c95f0dcSAl Viro return -EACCES; 24633c95f0dcSAl Viro } 24643c95f0dcSAl Viro /* 24653c95f0dcSAl Viro * See if the low-level filesystem might want 24663c95f0dcSAl Viro * to use its own hash.. 24673c95f0dcSAl Viro */ 24683c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24693c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24703c95f0dcSAl Viro if (err < 0) 24713c95f0dcSAl Viro return err; 24723c95f0dcSAl Viro } 24733c95f0dcSAl Viro 24743c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24753c95f0dcSAl Viro } 24763c95f0dcSAl Viro 2477eead1911SChristoph Hellwig /** 24780da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 24790da0b7fdSDavid Howells * @name: pathname component to lookup 24800da0b7fdSDavid Howells * @base: base directory to lookup from 24810da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 24820da0b7fdSDavid Howells * 24830da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 24840da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 24850da0b7fdSDavid Howells * 24860da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 24870da0b7fdSDavid Howells * not be called by generic code. 24880da0b7fdSDavid Howells * 24890da0b7fdSDavid Howells * The caller must hold base->i_mutex. 24900da0b7fdSDavid Howells */ 24910da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 24920da0b7fdSDavid Howells { 24930da0b7fdSDavid Howells struct qstr this; 24940da0b7fdSDavid Howells int err; 24950da0b7fdSDavid Howells 24960da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24970da0b7fdSDavid Howells 24980da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 24990da0b7fdSDavid Howells if (err) 25000da0b7fdSDavid Howells return ERR_PTR(err); 25010da0b7fdSDavid Howells 25020da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25030da0b7fdSDavid Howells } 25040da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25050da0b7fdSDavid Howells 25060da0b7fdSDavid Howells /** 2507a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2508eead1911SChristoph Hellwig * @name: pathname component to lookup 2509eead1911SChristoph Hellwig * @base: base directory to lookup from 2510eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2511eead1911SChristoph Hellwig * 2512a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25139e7543e9SAl Viro * not be called by generic code. 2514bbddca8eSNeilBrown * 2515bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2516eead1911SChristoph Hellwig */ 2517057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2518057f6c01SJames Morris { 25198613a209SAl Viro struct dentry *dentry; 2520057f6c01SJames Morris struct qstr this; 2521cda309deSMiklos Szeredi int err; 2522057f6c01SJames Morris 25235955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25242f9092e1SDavid Woodhouse 25253c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2526cda309deSMiklos Szeredi if (err) 2527cda309deSMiklos Szeredi return ERR_PTR(err); 2528cda309deSMiklos Szeredi 25298613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25308613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2531057f6c01SJames Morris } 25324d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2533057f6c01SJames Morris 2534bbddca8eSNeilBrown /** 2535bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2536bbddca8eSNeilBrown * @name: pathname component to lookup 2537bbddca8eSNeilBrown * @base: base directory to lookup from 2538bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2539bbddca8eSNeilBrown * 2540bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2541bbddca8eSNeilBrown * not be called by generic code. 2542bbddca8eSNeilBrown * 2543bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2544bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2545bbddca8eSNeilBrown */ 2546bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2547bbddca8eSNeilBrown struct dentry *base, int len) 2548bbddca8eSNeilBrown { 2549bbddca8eSNeilBrown struct qstr this; 2550bbddca8eSNeilBrown int err; 255120d00ee8SLinus Torvalds struct dentry *ret; 2552bbddca8eSNeilBrown 25533c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2554bbddca8eSNeilBrown if (err) 2555bbddca8eSNeilBrown return ERR_PTR(err); 2556bbddca8eSNeilBrown 255720d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 255820d00ee8SLinus Torvalds if (!ret) 255920d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 256020d00ee8SLinus Torvalds return ret; 2561bbddca8eSNeilBrown } 2562bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2563bbddca8eSNeilBrown 25646c2d4798SAl Viro /* 25656c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 25666c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 25676c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 25686c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 25696c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 25706c2d4798SAl Viro * this one avoids such problems. 25716c2d4798SAl Viro */ 25726c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 25736c2d4798SAl Viro struct dentry *base, int len) 25746c2d4798SAl Viro { 25756c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 25762fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 25776c2d4798SAl Viro dput(ret); 25786c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 25796c2d4798SAl Viro } 25806c2d4798SAl Viro return ret; 25816c2d4798SAl Viro } 25826c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 25836c2d4798SAl Viro 2584eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2585eedf265aSEric W. Biederman int path_pts(struct path *path) 2586eedf265aSEric W. Biederman { 2587eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2588eedf265aSEric W. Biederman * the input path. 2589eedf265aSEric W. Biederman */ 2590eedf265aSEric W. Biederman struct dentry *child, *parent; 2591eedf265aSEric W. Biederman struct qstr this; 2592eedf265aSEric W. Biederman int ret; 2593eedf265aSEric W. Biederman 2594eedf265aSEric W. Biederman ret = path_parent_directory(path); 2595eedf265aSEric W. Biederman if (ret) 2596eedf265aSEric W. Biederman return ret; 2597eedf265aSEric W. Biederman 2598eedf265aSEric W. Biederman parent = path->dentry; 2599eedf265aSEric W. Biederman this.name = "pts"; 2600eedf265aSEric W. Biederman this.len = 3; 2601eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2602eedf265aSEric W. Biederman if (!child) 2603eedf265aSEric W. Biederman return -ENOENT; 2604eedf265aSEric W. Biederman 2605eedf265aSEric W. Biederman path->dentry = child; 2606eedf265aSEric W. Biederman dput(parent); 2607eedf265aSEric W. Biederman follow_mount(path); 2608eedf265aSEric W. Biederman return 0; 2609eedf265aSEric W. Biederman } 2610eedf265aSEric W. Biederman #endif 2611eedf265aSEric W. Biederman 26121fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26131fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26141da177e4SLinus Torvalds { 2615abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2616abc9f5beSAl Viro flags, path, NULL); 26171da177e4SLinus Torvalds } 2618b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26191fa1e7f6SAndy Whitcroft 26208033426eSJeff Layton /** 2621197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26222a78b857SMasanari Iida * @nd: lookup context 26238033426eSJeff Layton * @flags: lookup flags 2624c8a53ee5SAl Viro * @path: pointer to container for result 26258033426eSJeff Layton * 26268033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2627606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26288033426eSJeff Layton */ 26298033426eSJeff Layton static int 2630c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26318033426eSJeff Layton { 2632c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2633368ee9baSAl Viro int err; 26349b5858e9SAl Viro 26353bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2636c64cd6e3SAl Viro (err = lookup_last(nd)) > 0) { 26373bdba28bSAl Viro s = trailing_symlink(nd); 26383bdba28bSAl Viro } 2639c64cd6e3SAl Viro if (!err && (nd->flags & LOOKUP_RCU)) 2640c64cd6e3SAl Viro err = unlazy_walk(nd); 2641c64cd6e3SAl Viro if (!err) 2642c64cd6e3SAl Viro err = handle_lookup_down(nd); 2643ba8f4613SAl Viro if (!err) { 2644ba8f4613SAl Viro *path = nd->path; 2645ba8f4613SAl Viro nd->path.mnt = NULL; 2646ba8f4613SAl Viro nd->path.dentry = NULL; 2647ba8f4613SAl Viro } 2648deb106c6SAl Viro terminate_walk(nd); 26498033426eSJeff Layton return err; 26508033426eSJeff Layton } 26518033426eSJeff Layton 26522d864651SAl Viro static int 2653668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26542d864651SAl Viro unsigned int flags) 26552d864651SAl Viro { 26569883d185SAl Viro struct nameidata nd; 2657cbaab2dbSAl Viro int error; 2658668696dcSAl Viro if (IS_ERR(name)) 2659668696dcSAl Viro return PTR_ERR(name); 26609883d185SAl Viro set_nameidata(&nd, dfd, name); 2661c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26622d864651SAl Viro if (unlikely(error == -ECHILD)) 2663c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26642d864651SAl Viro if (unlikely(error == -ESTALE)) 2665c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26662d864651SAl Viro if (likely(!error)) 2667c9b07eabSAl Viro audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); 26689883d185SAl Viro restore_nameidata(); 2669668696dcSAl Viro putname(name); 26702d864651SAl Viro return error; 26712d864651SAl Viro } 26722d864651SAl Viro 26738033426eSJeff Layton /** 2674197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26758033426eSJeff Layton * @dfd: directory file descriptor 26768033426eSJeff Layton * @name: pathname from userland 26778033426eSJeff Layton * @flags: lookup flags 26788033426eSJeff Layton * @path: pointer to container to hold result 26798033426eSJeff Layton * 26808033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26818033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26828033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26838033426eSJeff Layton * and avoid revalidating the last component. 26848033426eSJeff Layton * 26858033426eSJeff Layton * Returns 0 and populates "path" on success. 26868033426eSJeff Layton */ 26878033426eSJeff Layton int 2688197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26898033426eSJeff Layton struct path *path) 26908033426eSJeff Layton { 2691cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26928033426eSJeff Layton } 26938033426eSJeff Layton 26942d864651SAl Viro int 26952d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 26962d864651SAl Viro unsigned int flags) 26972d864651SAl Viro { 2698cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 26992d864651SAl Viro } 27002d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27012d864651SAl Viro 2702cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27031da177e4SLinus Torvalds { 27048e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2705da9592edSDavid Howells 27068e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27071da177e4SLinus Torvalds return 0; 27088e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27091da177e4SLinus Torvalds return 0; 271023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27111da177e4SLinus Torvalds } 2712cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds /* 27151da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27161da177e4SLinus Torvalds * whether the type of victim is right. 27171da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27181da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27191da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27201da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27211da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27221da177e4SLinus Torvalds * a. be owner of dir, or 27231da177e4SLinus Torvalds * b. be owner of victim, or 27241da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27251da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27261da177e4SLinus Torvalds * links pointing to it. 27270bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27280bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27290bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27300bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27310bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27321da177e4SLinus Torvalds * nfs_async_unlink(). 27331da177e4SLinus Torvalds */ 2734b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27351da177e4SLinus Torvalds { 273663afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27371da177e4SLinus Torvalds int error; 27381da177e4SLinus Torvalds 2739b18825a7SDavid Howells if (d_is_negative(victim)) 27401da177e4SLinus Torvalds return -ENOENT; 2741b18825a7SDavid Howells BUG_ON(!inode); 27421da177e4SLinus Torvalds 27431da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2744593d1ce8SEric W. Biederman 2745593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2746593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2747593d1ce8SEric W. Biederman return -EOVERFLOW; 2748593d1ce8SEric W. Biederman 27494fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27501da177e4SLinus Torvalds 2751f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27521da177e4SLinus Torvalds if (error) 27531da177e4SLinus Torvalds return error; 27541da177e4SLinus Torvalds if (IS_APPEND(dir)) 27551da177e4SLinus Torvalds return -EPERM; 2756b18825a7SDavid Howells 2757b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27580bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27591da177e4SLinus Torvalds return -EPERM; 27601da177e4SLinus Torvalds if (isdir) { 276144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27621da177e4SLinus Torvalds return -ENOTDIR; 27631da177e4SLinus Torvalds if (IS_ROOT(victim)) 27641da177e4SLinus Torvalds return -EBUSY; 276544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27661da177e4SLinus Torvalds return -EISDIR; 27671da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27681da177e4SLinus Torvalds return -ENOENT; 27691da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27701da177e4SLinus Torvalds return -EBUSY; 27711da177e4SLinus Torvalds return 0; 27721da177e4SLinus Torvalds } 27731da177e4SLinus Torvalds 27741da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27751da177e4SLinus Torvalds * dir. 27761da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27771da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27781da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2779036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2780036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2781036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27821da177e4SLinus Torvalds */ 2783a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27841da177e4SLinus Torvalds { 2785036d5236SEric W. Biederman struct user_namespace *s_user_ns; 278614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27871da177e4SLinus Torvalds if (child->d_inode) 27881da177e4SLinus Torvalds return -EEXIST; 27891da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27901da177e4SLinus Torvalds return -ENOENT; 2791036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2792036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2793036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2794036d5236SEric W. Biederman return -EOVERFLOW; 2795f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27961da177e4SLinus Torvalds } 27971da177e4SLinus Torvalds 27981da177e4SLinus Torvalds /* 27991da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28001da177e4SLinus Torvalds */ 28011da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28021da177e4SLinus Torvalds { 28031da177e4SLinus Torvalds struct dentry *p; 28041da177e4SLinus Torvalds 28051da177e4SLinus Torvalds if (p1 == p2) { 28065955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28071da177e4SLinus Torvalds return NULL; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 2810fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28111da177e4SLinus Torvalds 2812e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2813e2761a11SOGAWA Hirofumi if (p) { 28145955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28155955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28161da177e4SLinus Torvalds return p; 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds 2819e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2820e2761a11SOGAWA Hirofumi if (p) { 28215955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28225955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28231da177e4SLinus Torvalds return p; 28241da177e4SLinus Torvalds } 28251da177e4SLinus Torvalds 28265955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28275955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28281da177e4SLinus Torvalds return NULL; 28291da177e4SLinus Torvalds } 28304d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28311da177e4SLinus Torvalds 28321da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28331da177e4SLinus Torvalds { 28345955102cSAl Viro inode_unlock(p1->d_inode); 28351da177e4SLinus Torvalds if (p1 != p2) { 28365955102cSAl Viro inode_unlock(p2->d_inode); 2837fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28381da177e4SLinus Torvalds } 28391da177e4SLinus Torvalds } 28404d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28411da177e4SLinus Torvalds 28424acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2843312b63fbSAl Viro bool want_excl) 28441da177e4SLinus Torvalds { 2845a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28461da177e4SLinus Torvalds if (error) 28471da177e4SLinus Torvalds return error; 28481da177e4SLinus Torvalds 2849acfa4380SAl Viro if (!dir->i_op->create) 28501da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28511da177e4SLinus Torvalds mode &= S_IALLUGO; 28521da177e4SLinus Torvalds mode |= S_IFREG; 28531da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28541da177e4SLinus Torvalds if (error) 28551da177e4SLinus Torvalds return error; 2856312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2857a74574aaSStephen Smalley if (!error) 2858f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28591da177e4SLinus Torvalds return error; 28601da177e4SLinus Torvalds } 28614d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28621da177e4SLinus Torvalds 28638e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28648e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28658e6c848eSAl Viro void *arg) 28668e6c848eSAl Viro { 28678e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28688e6c848eSAl Viro int error = may_create(dir, dentry); 28698e6c848eSAl Viro if (error) 28708e6c848eSAl Viro return error; 28718e6c848eSAl Viro 28728e6c848eSAl Viro mode &= S_IALLUGO; 28738e6c848eSAl Viro mode |= S_IFREG; 28748e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28758e6c848eSAl Viro if (error) 28768e6c848eSAl Viro return error; 28778e6c848eSAl Viro error = f(dentry, mode, arg); 28788e6c848eSAl Viro if (!error) 28798e6c848eSAl Viro fsnotify_create(dir, dentry); 28808e6c848eSAl Viro return error; 28818e6c848eSAl Viro } 28828e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28838e6c848eSAl Viro 2884a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2885a2982cc9SEric W. Biederman { 2886a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2887a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2888a2982cc9SEric W. Biederman } 2889a2982cc9SEric W. Biederman 2890f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28911da177e4SLinus Torvalds { 28923fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28931da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28941da177e4SLinus Torvalds int error; 28951da177e4SLinus Torvalds 28961da177e4SLinus Torvalds if (!inode) 28971da177e4SLinus Torvalds return -ENOENT; 28981da177e4SLinus Torvalds 2899c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2900c8fe8f30SChristoph Hellwig case S_IFLNK: 29011da177e4SLinus Torvalds return -ELOOP; 2902c8fe8f30SChristoph Hellwig case S_IFDIR: 2903c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29041da177e4SLinus Torvalds return -EISDIR; 2905c8fe8f30SChristoph Hellwig break; 2906c8fe8f30SChristoph Hellwig case S_IFBLK: 2907c8fe8f30SChristoph Hellwig case S_IFCHR: 2908a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29091da177e4SLinus Torvalds return -EACCES; 2910c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2911c8fe8f30SChristoph Hellwig case S_IFIFO: 2912c8fe8f30SChristoph Hellwig case S_IFSOCK: 29131da177e4SLinus Torvalds flag &= ~O_TRUNC; 2914c8fe8f30SChristoph Hellwig break; 29154a3fd211SDave Hansen } 2916b41572e9SDave Hansen 291762fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2918b41572e9SDave Hansen if (error) 2919b41572e9SDave Hansen return error; 29206146f0d5SMimi Zohar 29211da177e4SLinus Torvalds /* 29221da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29231da177e4SLinus Torvalds */ 29241da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29258737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29267715b521SAl Viro return -EPERM; 29271da177e4SLinus Torvalds if (flag & O_TRUNC) 29287715b521SAl Viro return -EPERM; 29291da177e4SLinus Torvalds } 29301da177e4SLinus Torvalds 29311da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29322e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29337715b521SAl Viro return -EPERM; 29341da177e4SLinus Torvalds 2935f3c7691eSJ. Bruce Fields return 0; 29367715b521SAl Viro } 29377715b521SAl Viro 2938e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29397715b521SAl Viro { 2940f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29417715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29427715b521SAl Viro int error = get_write_access(inode); 29431da177e4SLinus Torvalds if (error) 29447715b521SAl Viro return error; 29451da177e4SLinus Torvalds /* 29461da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29471da177e4SLinus Torvalds */ 2948d7a06983SJeff Layton error = locks_verify_locked(filp); 2949be6d3e56SKentaro Takeda if (!error) 2950ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29511da177e4SLinus Torvalds if (!error) { 29527715b521SAl Viro error = do_truncate(path->dentry, 0, 2953d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2954e1181ee6SJeff Layton filp); 29551da177e4SLinus Torvalds } 29561da177e4SLinus Torvalds put_write_access(inode); 2957acd0c935SMimi Zohar return error; 29581da177e4SLinus Torvalds } 29591da177e4SLinus Torvalds 2960d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2961d57999e1SDave Hansen { 29628a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29638a5e929dSAl Viro flag--; 2964d57999e1SDave Hansen return flag; 2965d57999e1SDave Hansen } 2966d57999e1SDave Hansen 2967d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2968d18e9008SMiklos Szeredi { 29691328c727SSeth Forshee struct user_namespace *s_user_ns; 2970d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2971d18e9008SMiklos Szeredi if (error) 2972d18e9008SMiklos Szeredi return error; 2973d18e9008SMiklos Szeredi 29741328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29751328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29761328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29771328c727SSeth Forshee return -EOVERFLOW; 29781328c727SSeth Forshee 2979d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2980d18e9008SMiklos Szeredi if (error) 2981d18e9008SMiklos Szeredi return error; 2982d18e9008SMiklos Szeredi 2983d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2984d18e9008SMiklos Szeredi } 2985d18e9008SMiklos Szeredi 29861acf0af9SDavid Howells /* 29871acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29881acf0af9SDavid Howells * dentry. 29891acf0af9SDavid Howells * 29901acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29911acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29921acf0af9SDavid Howells * 299300a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 299400a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 299500a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29961acf0af9SDavid Howells * 29971acf0af9SDavid Howells * Returns an error code otherwise. 29981acf0af9SDavid Howells */ 29992675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 300030d90494SAl Viro struct path *path, struct file *file, 3001015c3bbcSMiklos Szeredi const struct open_flags *op, 30023ec2eef1SAl Viro int open_flag, umode_t mode) 3003d18e9008SMiklos Szeredi { 3004d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3005d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3006d18e9008SMiklos Szeredi int error; 3007d18e9008SMiklos Szeredi 3008384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3009d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3010d18e9008SMiklos Szeredi 3011d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3012d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3013d18e9008SMiklos Szeredi 301430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 301530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30160fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 301744907d79SAl Viro open_to_namei_flags(open_flag), mode); 30186fbd0714SAl Viro d_lookup_done(dentry); 3019384f26e2SAl Viro if (!error) { 302064e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3021d18e9008SMiklos Szeredi /* 3022384f26e2SAl Viro * We didn't have the inode before the open, so check open 3023384f26e2SAl Viro * permission here. 3024d18e9008SMiklos Szeredi */ 3025384f26e2SAl Viro int acc_mode = op->acc_mode; 302673a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 302703da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 302803da633aSAl Viro fsnotify_create(dir, dentry); 302962fb4a15SAl Viro acc_mode = 0; 303003da633aSAl Viro } 30312675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3032384f26e2SAl Viro if (WARN_ON(error > 0)) 3033384f26e2SAl Viro error = -EINVAL; 303464e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3035d18e9008SMiklos Szeredi error = -EIO; 3036384f26e2SAl Viro } else { 3037d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3038d18e9008SMiklos Szeredi dput(dentry); 3039d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 304010c64ceaSAl Viro } 304173a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3042d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3043a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3044a01e718fSAl Viro error = -ENOENT; 3045a01e718fSAl Viro } else { 3046d18e9008SMiklos Szeredi path->dentry = dentry; 3047d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 304800a07c15SAl Viro return 0; 3049d18e9008SMiklos Szeredi } 3050d18e9008SMiklos Szeredi } 3051a01e718fSAl Viro } 3052d18e9008SMiklos Szeredi dput(dentry); 3053d18e9008SMiklos Szeredi return error; 3054d18e9008SMiklos Szeredi } 3055d18e9008SMiklos Szeredi 305631e6b01fSNick Piggin /* 30571acf0af9SDavid Howells * Look up and maybe create and open the last component. 3058d58ffd35SMiklos Szeredi * 305900a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3060d58ffd35SMiklos Szeredi * 306100a07c15SAl Viro * Returns 0 on success, that is, if 306200a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 306300a07c15SAl Viro * the file was not completely opened at this time, though lookups and 306400a07c15SAl Viro * creations were performed. 306500a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 306600a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 306700a07c15SAl Viro * hadn't been specified. 30681acf0af9SDavid Howells * 306900a07c15SAl Viro * An error code is returned on failure. 3070d58ffd35SMiklos Szeredi */ 30712675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 307230d90494SAl Viro struct file *file, 3073d58ffd35SMiklos Szeredi const struct open_flags *op, 30743ec2eef1SAl Viro bool got_write) 3075d58ffd35SMiklos Szeredi { 3076d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 307754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30781643b43fSAl Viro int open_flag = op->open_flag; 3079d58ffd35SMiklos Szeredi struct dentry *dentry; 30801643b43fSAl Viro int error, create_error = 0; 30811643b43fSAl Viro umode_t mode = op->mode; 30826fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3083d58ffd35SMiklos Szeredi 3084ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3085ce8644fcSAl Viro return -ENOENT; 3086d58ffd35SMiklos Szeredi 308773a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30886fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30896fbd0714SAl Viro for (;;) { 30906fbd0714SAl Viro if (!dentry) { 30916fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3092d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30932675a4ebSAl Viro return PTR_ERR(dentry); 30946fbd0714SAl Viro } 30956fbd0714SAl Viro if (d_in_lookup(dentry)) 30966fbd0714SAl Viro break; 3097d58ffd35SMiklos Szeredi 30986fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30996fbd0714SAl Viro if (likely(error > 0)) 31006fbd0714SAl Viro break; 31016fbd0714SAl Viro if (error) 31026fbd0714SAl Viro goto out_dput; 31036fbd0714SAl Viro d_invalidate(dentry); 31046fbd0714SAl Viro dput(dentry); 31056fbd0714SAl Viro dentry = NULL; 31066fbd0714SAl Viro } 31076fbd0714SAl Viro if (dentry->d_inode) { 3108d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3109d18e9008SMiklos Szeredi goto out_no_open; 31106c51e513SAl Viro } 3111d18e9008SMiklos Szeredi 31121643b43fSAl Viro /* 31131643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31141643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31151643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31161643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31171643b43fSAl Viro * 31181643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31191643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31201643b43fSAl Viro */ 31211643b43fSAl Viro if (open_flag & O_CREAT) { 31221643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31231643b43fSAl Viro mode &= ~current_umask(); 31241643b43fSAl Viro if (unlikely(!got_write)) { 31251643b43fSAl Viro create_error = -EROFS; 31261643b43fSAl Viro open_flag &= ~O_CREAT; 31271643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31281643b43fSAl Viro goto no_open; 31291643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31301643b43fSAl Viro } else { 31311643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31321643b43fSAl Viro if (create_error) { 31331643b43fSAl Viro open_flag &= ~O_CREAT; 31341643b43fSAl Viro if (open_flag & O_EXCL) 31351643b43fSAl Viro goto no_open; 31361643b43fSAl Viro } 31371643b43fSAl Viro } 31381643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31391643b43fSAl Viro unlikely(!got_write)) { 31401643b43fSAl Viro /* 31411643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31421643b43fSAl Viro * back to lookup + open 31431643b43fSAl Viro */ 31441643b43fSAl Viro goto no_open; 3145d18e9008SMiklos Szeredi } 3146d18e9008SMiklos Szeredi 31471643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31481643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31493ec2eef1SAl Viro mode); 31501643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31511643b43fSAl Viro error = create_error; 31521643b43fSAl Viro return error; 31531643b43fSAl Viro } 315454ef4872SMiklos Szeredi 31551643b43fSAl Viro no_open: 31566fbd0714SAl Viro if (d_in_lookup(dentry)) { 315712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 315812fa5e24SAl Viro nd->flags); 31596fbd0714SAl Viro d_lookup_done(dentry); 316012fa5e24SAl Viro if (unlikely(res)) { 316112fa5e24SAl Viro if (IS_ERR(res)) { 316212fa5e24SAl Viro error = PTR_ERR(res); 316312fa5e24SAl Viro goto out_dput; 316412fa5e24SAl Viro } 316512fa5e24SAl Viro dput(dentry); 316612fa5e24SAl Viro dentry = res; 316712fa5e24SAl Viro } 316854ef4872SMiklos Szeredi } 316954ef4872SMiklos Szeredi 3170d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31711643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 317273a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3173ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3174ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3175ce8644fcSAl Viro error = -EACCES; 3176d58ffd35SMiklos Szeredi goto out_dput; 317764894cf8SAl Viro } 3178ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31791643b43fSAl Viro open_flag & O_EXCL); 3180d58ffd35SMiklos Szeredi if (error) 3181d58ffd35SMiklos Szeredi goto out_dput; 3182ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3183d58ffd35SMiklos Szeredi } 31841643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31851643b43fSAl Viro error = create_error; 3186d58ffd35SMiklos Szeredi goto out_dput; 3187d58ffd35SMiklos Szeredi } 3188d18e9008SMiklos Szeredi out_no_open: 3189d58ffd35SMiklos Szeredi path->dentry = dentry; 3190d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 319100a07c15SAl Viro return 0; 3192d58ffd35SMiklos Szeredi 3193d58ffd35SMiklos Szeredi out_dput: 3194d58ffd35SMiklos Szeredi dput(dentry); 31952675a4ebSAl Viro return error; 3196d58ffd35SMiklos Szeredi } 3197d58ffd35SMiklos Szeredi 3198d58ffd35SMiklos Szeredi /* 3199fe2d35ffSAl Viro * Handle the last step of open() 320031e6b01fSNick Piggin */ 3201896475d5SAl Viro static int do_last(struct nameidata *nd, 32023ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3203fb1cc555SAl Viro { 3204a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3205d0cb5018SAl Viro kuid_t dir_uid = dir->d_inode->i_uid; 3206d0cb5018SAl Viro umode_t dir_mode = dir->d_inode->i_mode; 3207ca344a89SAl Viro int open_flag = op->open_flag; 320877d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 320964894cf8SAl Viro bool got_write = false; 3210bcda7652SAl Viro int acc_mode = op->acc_mode; 3211254cf582SAl Viro unsigned seq; 3212a1eb3315SMiklos Szeredi struct inode *inode; 3213896475d5SAl Viro struct path path; 321416c2cd71SAl Viro int error; 3215fb1cc555SAl Viro 3216c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3217c3e380b0SAl Viro nd->flags |= op->intent; 3218c3e380b0SAl Viro 3219bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3220fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3221deb106c6SAl Viro if (unlikely(error)) 32222675a4ebSAl Viro return error; 3223e83db167SMiklos Szeredi goto finish_open; 32241f36f774SAl Viro } 3225a2c36b45SAl Viro 3226ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3227fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3228fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3229fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3230254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3231e9742b53SAl Viro if (likely(error > 0)) 323271574865SMiklos Szeredi goto finish_lookup; 323371574865SMiklos Szeredi 3234ce57dfc1SAl Viro if (error < 0) 3235deb106c6SAl Viro return error; 3236a1eb3315SMiklos Szeredi 323737d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32386583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3239b6183df7SMiklos Szeredi } else { 3240fe2d35ffSAl Viro /* create side of things */ 3241a3fbbde7SAl Viro /* 3242b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3243b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3244b6183df7SMiklos Szeredi * about to look up 3245a3fbbde7SAl Viro */ 32469f1fafeeSAl Viro error = complete_walk(nd); 3247e8bb73dfSAl Viro if (error) 32482675a4ebSAl Viro return error; 3249fe2d35ffSAl Viro 3250c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32511f36f774SAl Viro /* trailing slashes? */ 3252deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3253deb106c6SAl Viro return -EISDIR; 3254b6183df7SMiklos Szeredi } 32551f36f774SAl Viro 32569cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 325764894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 325864894cf8SAl Viro if (!error) 325964894cf8SAl Viro got_write = true; 326064894cf8SAl Viro /* 326164894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 326264894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 326364894cf8SAl Viro * dropping this one anyway. 326464894cf8SAl Viro */ 326564894cf8SAl Viro } 32669cf843e3SAl Viro if (open_flag & O_CREAT) 32675955102cSAl Viro inode_lock(dir->d_inode); 32689cf843e3SAl Viro else 32699cf843e3SAl Viro inode_lock_shared(dir->d_inode); 32703ec2eef1SAl Viro error = lookup_open(nd, &path, file, op, got_write); 32719cf843e3SAl Viro if (open_flag & O_CREAT) 32725955102cSAl Viro inode_unlock(dir->d_inode); 32739cf843e3SAl Viro else 32749cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3275fb1cc555SAl Viro 32762675a4ebSAl Viro if (error) 3277d58ffd35SMiklos Szeredi goto out; 32786c0d46c4SAl Viro 327900a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 328073a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3281496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 328277d660a8SMiklos Szeredi will_truncate = false; 3283d18e9008SMiklos Szeredi 328476ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3285d18e9008SMiklos Szeredi goto opened; 3286d18e9008SMiklos Szeredi } 3287d18e9008SMiklos Szeredi 328873a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 32899b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3290ca344a89SAl Viro open_flag &= ~O_TRUNC; 329177d660a8SMiklos Szeredi will_truncate = false; 329262fb4a15SAl Viro acc_mode = 0; 3293896475d5SAl Viro path_to_nameidata(&path, nd); 3294e83db167SMiklos Szeredi goto finish_open_created; 3295fb1cc555SAl Viro } 3296fb1cc555SAl Viro 3297fb1cc555SAl Viro /* 3298d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3299d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3300d18e9008SMiklos Szeredi * necessary...) 3301d18e9008SMiklos Szeredi */ 330264894cf8SAl Viro if (got_write) { 3303d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 330464894cf8SAl Viro got_write = false; 3305d18e9008SMiklos Szeredi } 3306d18e9008SMiklos Szeredi 3307e6ec03a2SAl Viro error = follow_managed(&path, nd); 3308e6ec03a2SAl Viro if (unlikely(error < 0)) 3309e6ec03a2SAl Viro return error; 3310e6ec03a2SAl Viro 33116583fe22SAl Viro /* 33126583fe22SAl Viro * create/update audit record if it already exists. 33136583fe22SAl Viro */ 33146583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33156583fe22SAl Viro 3316deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3317deb106c6SAl Viro path_to_nameidata(&path, nd); 3318deb106c6SAl Viro return -EEXIST; 3319deb106c6SAl Viro } 3320fb1cc555SAl Viro 3321254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3322d4565649SAl Viro inode = d_backing_inode(path.dentry); 3323766c4cbfSAl Viro finish_lookup: 33248f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3325deb106c6SAl Viro if (unlikely(error)) 3326d63ff28fSAl Viro return error; 3327bc77daa7SAl Viro finish_open: 33288f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3329a3fbbde7SAl Viro error = complete_walk(nd); 3330fac7d191SAl Viro if (error) 33312675a4ebSAl Viro return error; 333276ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 333330aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3334fb1cc555SAl Viro error = -EISDIR; 333530aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 33362675a4ebSAl Viro goto out; 3337d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 333830aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 333930aba665SSalvatore Mesoraca if (unlikely(error)) 334030aba665SSalvatore Mesoraca goto out; 334130aba665SSalvatore Mesoraca } 3342af2f5542SMiklos Szeredi error = -ENOTDIR; 334344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33442675a4ebSAl Viro goto out; 33454bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 334677d660a8SMiklos Szeredi will_truncate = false; 33476c0d46c4SAl Viro 33480f9d1a10SAl Viro if (will_truncate) { 33490f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33500f9d1a10SAl Viro if (error) 33512675a4ebSAl Viro goto out; 335264894cf8SAl Viro got_write = true; 33530f9d1a10SAl Viro } 3354e83db167SMiklos Szeredi finish_open_created: 3355bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3356ca344a89SAl Viro if (error) 33572675a4ebSAl Viro goto out; 3358aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3359ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3360fac7d191SAl Viro if (error) 3361015c3bbcSMiklos Szeredi goto out; 3362a8277b9bSMiklos Szeredi opened: 33636035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3364fe9ec829SAl Viro if (!error && will_truncate) 33652675a4ebSAl Viro error = handle_truncate(file); 3366ca344a89SAl Viro out: 3367c80567c8SAl Viro if (unlikely(error > 0)) { 3368c80567c8SAl Viro WARN_ON(1); 3369c80567c8SAl Viro error = -EINVAL; 3370c80567c8SAl Viro } 337164894cf8SAl Viro if (got_write) 33720f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33732675a4ebSAl Viro return error; 3374fb1cc555SAl Viro } 3375fb1cc555SAl Viro 3376af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3377af7bd4dcSAmir Goldstein { 3378af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3379af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3380af7bd4dcSAmir Goldstein struct inode *inode; 3381af7bd4dcSAmir Goldstein int error; 3382af7bd4dcSAmir Goldstein 3383af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3384af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3385af7bd4dcSAmir Goldstein if (error) 3386af7bd4dcSAmir Goldstein goto out_err; 3387af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3388af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3389af7bd4dcSAmir Goldstein goto out_err; 3390af7bd4dcSAmir Goldstein error = -ENOMEM; 3391cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3392af7bd4dcSAmir Goldstein if (unlikely(!child)) 3393af7bd4dcSAmir Goldstein goto out_err; 3394af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3395af7bd4dcSAmir Goldstein if (error) 3396af7bd4dcSAmir Goldstein goto out_err; 3397af7bd4dcSAmir Goldstein error = -ENOENT; 3398af7bd4dcSAmir Goldstein inode = child->d_inode; 3399af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3400af7bd4dcSAmir Goldstein goto out_err; 3401af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3402af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3403af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3404af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3405af7bd4dcSAmir Goldstein } 3406fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3407af7bd4dcSAmir Goldstein return child; 3408af7bd4dcSAmir Goldstein 3409af7bd4dcSAmir Goldstein out_err: 3410af7bd4dcSAmir Goldstein dput(child); 3411af7bd4dcSAmir Goldstein return ERR_PTR(error); 3412af7bd4dcSAmir Goldstein } 3413af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3414af7bd4dcSAmir Goldstein 3415c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 341660545d0dSAl Viro const struct open_flags *op, 34173ec2eef1SAl Viro struct file *file) 341860545d0dSAl Viro { 3419625b6d10SAl Viro struct dentry *child; 3420625b6d10SAl Viro struct path path; 3421c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 342260545d0dSAl Viro if (unlikely(error)) 342360545d0dSAl Viro return error; 3424625b6d10SAl Viro error = mnt_want_write(path.mnt); 342560545d0dSAl Viro if (unlikely(error)) 342660545d0dSAl Viro goto out; 3427af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3428af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3429684e73beSHirofumi Nakagawa if (IS_ERR(child)) 343060545d0dSAl Viro goto out2; 3431625b6d10SAl Viro dput(path.dentry); 3432625b6d10SAl Viro path.dentry = child; 3433c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 343469a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 343562fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 343660545d0dSAl Viro if (error) 343760545d0dSAl Viro goto out2; 3438625b6d10SAl Viro file->f_path.mnt = path.mnt; 3439be12af3eSAl Viro error = finish_open(file, child, NULL); 344060545d0dSAl Viro out2: 3441625b6d10SAl Viro mnt_drop_write(path.mnt); 344260545d0dSAl Viro out: 3443625b6d10SAl Viro path_put(&path); 344460545d0dSAl Viro return error; 344560545d0dSAl Viro } 344660545d0dSAl Viro 34476ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34486ac08709SAl Viro { 34496ac08709SAl Viro struct path path; 34506ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34516ac08709SAl Viro if (!error) { 34526ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3453ae2bb293SAl Viro error = vfs_open(&path, file); 34546ac08709SAl Viro path_put(&path); 34556ac08709SAl Viro } 34566ac08709SAl Viro return error; 34576ac08709SAl Viro } 34586ac08709SAl Viro 3459c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3460c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34611da177e4SLinus Torvalds { 346230d90494SAl Viro struct file *file; 346313aab428SAl Viro int error; 346431e6b01fSNick Piggin 3465ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 34661afc99beSAl Viro if (IS_ERR(file)) 34671afc99beSAl Viro return file; 346831e6b01fSNick Piggin 3469bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 34703ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 34715f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 34726ac08709SAl Viro error = do_o_path(nd, flags, file); 34735f336e72SAl Viro } else { 34745f336e72SAl Viro const char *s = path_init(nd, flags); 34753bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 34763ec2eef1SAl Viro (error = do_last(nd, file, op)) > 0) { 347773d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 34783bdba28bSAl Viro s = trailing_symlink(nd); 34793bdba28bSAl Viro } 3480deb106c6SAl Viro terminate_walk(nd); 34815f336e72SAl Viro } 34827c1c01ecSAl Viro if (likely(!error)) { 3483aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34847c1c01ecSAl Viro return file; 34857c1c01ecSAl Viro WARN_ON(1); 34867c1c01ecSAl Viro error = -EINVAL; 3487015c3bbcSMiklos Szeredi } 34887c1c01ecSAl Viro fput(file); 34892675a4ebSAl Viro if (error == -EOPENSTALE) { 34902675a4ebSAl Viro if (flags & LOOKUP_RCU) 34912675a4ebSAl Viro error = -ECHILD; 34922675a4ebSAl Viro else 34932675a4ebSAl Viro error = -ESTALE; 34942675a4ebSAl Viro } 34957c1c01ecSAl Viro return ERR_PTR(error); 3496de459215SKirill Korotaev } 34971da177e4SLinus Torvalds 3498669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3499f9652e10SAl Viro const struct open_flags *op) 350013aab428SAl Viro { 35019883d185SAl Viro struct nameidata nd; 3502f9652e10SAl Viro int flags = op->lookup_flags; 350313aab428SAl Viro struct file *filp; 350413aab428SAl Viro 35059883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3506c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 350713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3508c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 350913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3510c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35119883d185SAl Viro restore_nameidata(); 351213aab428SAl Viro return filp; 351313aab428SAl Viro } 351413aab428SAl Viro 351573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3516f9652e10SAl Viro const char *name, const struct open_flags *op) 351773d049a4SAl Viro { 35189883d185SAl Viro struct nameidata nd; 351973d049a4SAl Viro struct file *file; 352051689104SPaul Moore struct filename *filename; 3521f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 352273d049a4SAl Viro 352373d049a4SAl Viro nd.root.mnt = mnt; 352473d049a4SAl Viro nd.root.dentry = dentry; 352573d049a4SAl Viro 3526b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 352773d049a4SAl Viro return ERR_PTR(-ELOOP); 352873d049a4SAl Viro 352951689104SPaul Moore filename = getname_kernel(name); 3530a1c83681SViresh Kumar if (IS_ERR(filename)) 353151689104SPaul Moore return ERR_CAST(filename); 353251689104SPaul Moore 35339883d185SAl Viro set_nameidata(&nd, -1, filename); 3534c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 353573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3536c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 353773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3538c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35399883d185SAl Viro restore_nameidata(); 354051689104SPaul Moore putname(filename); 354173d049a4SAl Viro return file; 354273d049a4SAl Viro } 354373d049a4SAl Viro 3544fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35451ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35461da177e4SLinus Torvalds { 3547c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3548391172c4SAl Viro struct qstr last; 3549391172c4SAl Viro int type; 3550c30dabfeSJan Kara int err2; 35511ac12b4bSJeff Layton int error; 35521ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35531ac12b4bSJeff Layton 35541ac12b4bSJeff Layton /* 35551ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35561ac12b4bSJeff Layton * other flags passed in are ignored! 35571ac12b4bSJeff Layton */ 35581ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35591ac12b4bSJeff Layton 35605c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35615c31b6ceSAl Viro if (IS_ERR(name)) 35625c31b6ceSAl Viro return ERR_CAST(name); 35631da177e4SLinus Torvalds 3564c663e5d8SChristoph Hellwig /* 3565c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3566c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3567c663e5d8SChristoph Hellwig */ 35685c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3569ed75e95dSAl Viro goto out; 3570c663e5d8SChristoph Hellwig 3571c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3572391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3573c663e5d8SChristoph Hellwig /* 3574c663e5d8SChristoph Hellwig * Do the final lookup. 3575c663e5d8SChristoph Hellwig */ 3576391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35775955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3578391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35791da177e4SLinus Torvalds if (IS_ERR(dentry)) 3580a8104a9fSAl Viro goto unlock; 3581c663e5d8SChristoph Hellwig 3582a8104a9fSAl Viro error = -EEXIST; 3583b18825a7SDavid Howells if (d_is_positive(dentry)) 3584a8104a9fSAl Viro goto fail; 3585b18825a7SDavid Howells 3586c663e5d8SChristoph Hellwig /* 3587c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3588c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3589c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3590c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3591c663e5d8SChristoph Hellwig */ 3592391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3593a8104a9fSAl Viro error = -ENOENT; 3594ed75e95dSAl Viro goto fail; 3595e9baf6e5SAl Viro } 3596c30dabfeSJan Kara if (unlikely(err2)) { 3597c30dabfeSJan Kara error = err2; 3598a8104a9fSAl Viro goto fail; 3599c30dabfeSJan Kara } 3600181c37b6SAl Viro putname(name); 3601e9baf6e5SAl Viro return dentry; 36021da177e4SLinus Torvalds fail: 3603a8104a9fSAl Viro dput(dentry); 3604a8104a9fSAl Viro dentry = ERR_PTR(error); 3605a8104a9fSAl Viro unlock: 36065955102cSAl Viro inode_unlock(path->dentry->d_inode); 3607c30dabfeSJan Kara if (!err2) 3608391172c4SAl Viro mnt_drop_write(path->mnt); 3609ed75e95dSAl Viro out: 3610391172c4SAl Viro path_put(path); 3611181c37b6SAl Viro putname(name); 3612ed75e95dSAl Viro return dentry; 3613dae6ad8fSAl Viro } 3614fa14a0b8SAl Viro 3615fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3616fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3617fa14a0b8SAl Viro { 3618181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3619181c37b6SAl Viro path, lookup_flags); 3620fa14a0b8SAl Viro } 3621dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3622dae6ad8fSAl Viro 3623921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3624921a1650SAl Viro { 3625921a1650SAl Viro dput(dentry); 36265955102cSAl Viro inode_unlock(path->dentry->d_inode); 3627a8104a9fSAl Viro mnt_drop_write(path->mnt); 3628921a1650SAl Viro path_put(path); 3629921a1650SAl Viro } 3630921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3631921a1650SAl Viro 3632520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36331ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3634dae6ad8fSAl Viro { 3635181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3636dae6ad8fSAl Viro } 3637dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3638dae6ad8fSAl Viro 36391a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36401da177e4SLinus Torvalds { 3641a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36421da177e4SLinus Torvalds 36431da177e4SLinus Torvalds if (error) 36441da177e4SLinus Torvalds return error; 36451da177e4SLinus Torvalds 364694f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36471da177e4SLinus Torvalds return -EPERM; 36481da177e4SLinus Torvalds 3649acfa4380SAl Viro if (!dir->i_op->mknod) 36501da177e4SLinus Torvalds return -EPERM; 36511da177e4SLinus Torvalds 365208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 365308ce5f16SSerge E. Hallyn if (error) 365408ce5f16SSerge E. Hallyn return error; 365508ce5f16SSerge E. Hallyn 36561da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36571da177e4SLinus Torvalds if (error) 36581da177e4SLinus Torvalds return error; 36591da177e4SLinus Torvalds 36601da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3661a74574aaSStephen Smalley if (!error) 3662f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36631da177e4SLinus Torvalds return error; 36641da177e4SLinus Torvalds } 36654d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36661da177e4SLinus Torvalds 3667f69aac00SAl Viro static int may_mknod(umode_t mode) 3668463c3197SDave Hansen { 3669463c3197SDave Hansen switch (mode & S_IFMT) { 3670463c3197SDave Hansen case S_IFREG: 3671463c3197SDave Hansen case S_IFCHR: 3672463c3197SDave Hansen case S_IFBLK: 3673463c3197SDave Hansen case S_IFIFO: 3674463c3197SDave Hansen case S_IFSOCK: 3675463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3676463c3197SDave Hansen return 0; 3677463c3197SDave Hansen case S_IFDIR: 3678463c3197SDave Hansen return -EPERM; 3679463c3197SDave Hansen default: 3680463c3197SDave Hansen return -EINVAL; 3681463c3197SDave Hansen } 3682463c3197SDave Hansen } 3683463c3197SDave Hansen 368487c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 368587c4e192SDominik Brodowski unsigned int dev) 36861da177e4SLinus Torvalds { 36871da177e4SLinus Torvalds struct dentry *dentry; 3688dae6ad8fSAl Viro struct path path; 3689dae6ad8fSAl Viro int error; 3690972567f1SJeff Layton unsigned int lookup_flags = 0; 36911da177e4SLinus Torvalds 36928e4bfca1SAl Viro error = may_mknod(mode); 36938e4bfca1SAl Viro if (error) 36948e4bfca1SAl Viro return error; 3695972567f1SJeff Layton retry: 3696972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3697dae6ad8fSAl Viro if (IS_ERR(dentry)) 3698dae6ad8fSAl Viro return PTR_ERR(dentry); 36992ad94ae6SAl Viro 3700dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3701ce3b0f8dSAl Viro mode &= ~current_umask(); 3702dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3703be6d3e56SKentaro Takeda if (error) 3704a8104a9fSAl Viro goto out; 37051da177e4SLinus Torvalds switch (mode & S_IFMT) { 37061da177e4SLinus Torvalds case 0: case S_IFREG: 3707312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 370805d1a717SMimi Zohar if (!error) 370905d1a717SMimi Zohar ima_post_path_mknod(dentry); 37101da177e4SLinus Torvalds break; 37111da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3712dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37131da177e4SLinus Torvalds new_decode_dev(dev)); 37141da177e4SLinus Torvalds break; 37151da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3716dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37171da177e4SLinus Torvalds break; 37181da177e4SLinus Torvalds } 3719a8104a9fSAl Viro out: 3720921a1650SAl Viro done_path_create(&path, dentry); 3721972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3722972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3723972567f1SJeff Layton goto retry; 3724972567f1SJeff Layton } 37251da177e4SLinus Torvalds return error; 37261da177e4SLinus Torvalds } 37271da177e4SLinus Torvalds 372887c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 372987c4e192SDominik Brodowski unsigned int, dev) 373087c4e192SDominik Brodowski { 373187c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 373287c4e192SDominik Brodowski } 373387c4e192SDominik Brodowski 37348208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37355590ff0dSUlrich Drepper { 373687c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 37375590ff0dSUlrich Drepper } 37385590ff0dSUlrich Drepper 373918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37401da177e4SLinus Torvalds { 3741a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37428de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37431da177e4SLinus Torvalds 37441da177e4SLinus Torvalds if (error) 37451da177e4SLinus Torvalds return error; 37461da177e4SLinus Torvalds 3747acfa4380SAl Viro if (!dir->i_op->mkdir) 37481da177e4SLinus Torvalds return -EPERM; 37491da177e4SLinus Torvalds 37501da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37511da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37521da177e4SLinus Torvalds if (error) 37531da177e4SLinus Torvalds return error; 37541da177e4SLinus Torvalds 37558de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37568de52778SAl Viro return -EMLINK; 37578de52778SAl Viro 37581da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3759a74574aaSStephen Smalley if (!error) 3760f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37611da177e4SLinus Torvalds return error; 37621da177e4SLinus Torvalds } 37634d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37641da177e4SLinus Torvalds 37650101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 37661da177e4SLinus Torvalds { 37676902d925SDave Hansen struct dentry *dentry; 3768dae6ad8fSAl Viro struct path path; 3769dae6ad8fSAl Viro int error; 3770b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37711da177e4SLinus Torvalds 3772b76d8b82SJeff Layton retry: 3773b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37746902d925SDave Hansen if (IS_ERR(dentry)) 3775dae6ad8fSAl Viro return PTR_ERR(dentry); 37766902d925SDave Hansen 3777dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3778ce3b0f8dSAl Viro mode &= ~current_umask(); 3779dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3780a8104a9fSAl Viro if (!error) 3781dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3782921a1650SAl Viro done_path_create(&path, dentry); 3783b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3784b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3785b76d8b82SJeff Layton goto retry; 3786b76d8b82SJeff Layton } 37871da177e4SLinus Torvalds return error; 37881da177e4SLinus Torvalds } 37891da177e4SLinus Torvalds 37900101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37910101db7aSDominik Brodowski { 37920101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37930101db7aSDominik Brodowski } 37940101db7aSDominik Brodowski 3795a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37965590ff0dSUlrich Drepper { 37970101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37985590ff0dSUlrich Drepper } 37995590ff0dSUlrich Drepper 38001da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38011da177e4SLinus Torvalds { 38021da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38031da177e4SLinus Torvalds 38041da177e4SLinus Torvalds if (error) 38051da177e4SLinus Torvalds return error; 38061da177e4SLinus Torvalds 3807acfa4380SAl Viro if (!dir->i_op->rmdir) 38081da177e4SLinus Torvalds return -EPERM; 38091da177e4SLinus Torvalds 38101d2ef590SAl Viro dget(dentry); 38115955102cSAl Viro inode_lock(dentry->d_inode); 3812912dbc15SSage Weil 38131da177e4SLinus Torvalds error = -EBUSY; 38147af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3815912dbc15SSage Weil goto out; 3816912dbc15SSage Weil 38171da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3818912dbc15SSage Weil if (error) 3819912dbc15SSage Weil goto out; 3820912dbc15SSage Weil 38211da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3822912dbc15SSage Weil if (error) 3823912dbc15SSage Weil goto out; 3824912dbc15SSage Weil 38258767712fSAl Viro shrink_dcache_parent(dentry); 38261da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3827d83c49f3SAl Viro dont_mount(dentry); 38288ed936b5SEric W. Biederman detach_mounts(dentry); 3829116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 38301da177e4SLinus Torvalds 3831912dbc15SSage Weil out: 38325955102cSAl Viro inode_unlock(dentry->d_inode); 38331d2ef590SAl Viro dput(dentry); 3834912dbc15SSage Weil if (!error) 3835912dbc15SSage Weil d_delete(dentry); 38361da177e4SLinus Torvalds return error; 38371da177e4SLinus Torvalds } 38384d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38391da177e4SLinus Torvalds 3840f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 38411da177e4SLinus Torvalds { 38421da177e4SLinus Torvalds int error = 0; 384391a27b2aSJeff Layton struct filename *name; 38441da177e4SLinus Torvalds struct dentry *dentry; 3845f5beed75SAl Viro struct path path; 3846f5beed75SAl Viro struct qstr last; 3847f5beed75SAl Viro int type; 3848c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3849c6ee9206SJeff Layton retry: 3850c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3851c1d4dd27SAl Viro &path, &last, &type); 385291a27b2aSJeff Layton if (IS_ERR(name)) 385391a27b2aSJeff Layton return PTR_ERR(name); 38541da177e4SLinus Torvalds 3855f5beed75SAl Viro switch (type) { 38561da177e4SLinus Torvalds case LAST_DOTDOT: 38571da177e4SLinus Torvalds error = -ENOTEMPTY; 38581da177e4SLinus Torvalds goto exit1; 38591da177e4SLinus Torvalds case LAST_DOT: 38601da177e4SLinus Torvalds error = -EINVAL; 38611da177e4SLinus Torvalds goto exit1; 38621da177e4SLinus Torvalds case LAST_ROOT: 38631da177e4SLinus Torvalds error = -EBUSY; 38641da177e4SLinus Torvalds goto exit1; 38651da177e4SLinus Torvalds } 38660612d9fbSOGAWA Hirofumi 3867f5beed75SAl Viro error = mnt_want_write(path.mnt); 3868c30dabfeSJan Kara if (error) 3869c30dabfeSJan Kara goto exit1; 38700612d9fbSOGAWA Hirofumi 38715955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3872f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38731da177e4SLinus Torvalds error = PTR_ERR(dentry); 38746902d925SDave Hansen if (IS_ERR(dentry)) 38756902d925SDave Hansen goto exit2; 3876e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3877e6bc45d6STheodore Ts'o error = -ENOENT; 3878e6bc45d6STheodore Ts'o goto exit3; 3879e6bc45d6STheodore Ts'o } 3880f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3881be6d3e56SKentaro Takeda if (error) 3882c30dabfeSJan Kara goto exit3; 3883f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38840622753bSDave Hansen exit3: 38851da177e4SLinus Torvalds dput(dentry); 38866902d925SDave Hansen exit2: 38875955102cSAl Viro inode_unlock(path.dentry->d_inode); 3888f5beed75SAl Viro mnt_drop_write(path.mnt); 38891da177e4SLinus Torvalds exit1: 3890f5beed75SAl Viro path_put(&path); 38911da177e4SLinus Torvalds putname(name); 3892c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3893c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3894c6ee9206SJeff Layton goto retry; 3895c6ee9206SJeff Layton } 38961da177e4SLinus Torvalds return error; 38971da177e4SLinus Torvalds } 38981da177e4SLinus Torvalds 38993cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39005590ff0dSUlrich Drepper { 39015590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39025590ff0dSUlrich Drepper } 39035590ff0dSUlrich Drepper 3904b21996e3SJ. Bruce Fields /** 3905b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3906b21996e3SJ. Bruce Fields * @dir: parent directory 3907b21996e3SJ. Bruce Fields * @dentry: victim 3908b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3909b21996e3SJ. Bruce Fields * 3910b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3911b21996e3SJ. Bruce Fields * 3912b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3913b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3914b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3915b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3916b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3917b21996e3SJ. Bruce Fields * 3918b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3919b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3920b21996e3SJ. Bruce Fields * to be NFS exported. 3921b21996e3SJ. Bruce Fields */ 3922b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39231da177e4SLinus Torvalds { 39249accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39251da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39261da177e4SLinus Torvalds 39271da177e4SLinus Torvalds if (error) 39281da177e4SLinus Torvalds return error; 39291da177e4SLinus Torvalds 3930acfa4380SAl Viro if (!dir->i_op->unlink) 39311da177e4SLinus Torvalds return -EPERM; 39321da177e4SLinus Torvalds 39335955102cSAl Viro inode_lock(target); 39348ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39351da177e4SLinus Torvalds error = -EBUSY; 39361da177e4SLinus Torvalds else { 39371da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3938bec1052eSAl Viro if (!error) { 39395a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39405a14696cSJ. Bruce Fields if (error) 3941b21996e3SJ. Bruce Fields goto out; 39421da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39438ed936b5SEric W. Biederman if (!error) { 3944d83c49f3SAl Viro dont_mount(dentry); 39458ed936b5SEric W. Biederman detach_mounts(dentry); 3946116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 39478ed936b5SEric W. Biederman } 3948bec1052eSAl Viro } 39491da177e4SLinus Torvalds } 3950b21996e3SJ. Bruce Fields out: 39515955102cSAl Viro inode_unlock(target); 39521da177e4SLinus Torvalds 39531da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39541da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39559accbb97SJ. Bruce Fields fsnotify_link_count(target); 39561da177e4SLinus Torvalds d_delete(dentry); 39571da177e4SLinus Torvalds } 39580eeca283SRobert Love 39591da177e4SLinus Torvalds return error; 39601da177e4SLinus Torvalds } 39614d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39621da177e4SLinus Torvalds 39631da177e4SLinus Torvalds /* 39641da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39651b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39661da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39671da177e4SLinus Torvalds * while waiting on the I/O. 39681da177e4SLinus Torvalds */ 3969da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39701da177e4SLinus Torvalds { 39712ad94ae6SAl Viro int error; 39721da177e4SLinus Torvalds struct dentry *dentry; 3973f5beed75SAl Viro struct path path; 3974f5beed75SAl Viro struct qstr last; 3975f5beed75SAl Viro int type; 39761da177e4SLinus Torvalds struct inode *inode = NULL; 3977b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39785d18f813SJeff Layton unsigned int lookup_flags = 0; 39795d18f813SJeff Layton retry: 3980da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 398191a27b2aSJeff Layton if (IS_ERR(name)) 398291a27b2aSJeff Layton return PTR_ERR(name); 39832ad94ae6SAl Viro 39841da177e4SLinus Torvalds error = -EISDIR; 3985f5beed75SAl Viro if (type != LAST_NORM) 39861da177e4SLinus Torvalds goto exit1; 39870612d9fbSOGAWA Hirofumi 3988f5beed75SAl Viro error = mnt_want_write(path.mnt); 3989c30dabfeSJan Kara if (error) 3990c30dabfeSJan Kara goto exit1; 3991b21996e3SJ. Bruce Fields retry_deleg: 39925955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3993f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39941da177e4SLinus Torvalds error = PTR_ERR(dentry); 39951da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39961da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3997f5beed75SAl Viro if (last.name[last.len]) 399850338b88STörök Edwin goto slashes; 39991da177e4SLinus Torvalds inode = dentry->d_inode; 4000b18825a7SDavid Howells if (d_is_negative(dentry)) 4001e6bc45d6STheodore Ts'o goto slashes; 40027de9c6eeSAl Viro ihold(inode); 4003f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4004be6d3e56SKentaro Takeda if (error) 4005c30dabfeSJan Kara goto exit2; 4006f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40071da177e4SLinus Torvalds exit2: 40081da177e4SLinus Torvalds dput(dentry); 40091da177e4SLinus Torvalds } 40105955102cSAl Viro inode_unlock(path.dentry->d_inode); 40111da177e4SLinus Torvalds if (inode) 40121da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4013b21996e3SJ. Bruce Fields inode = NULL; 4014b21996e3SJ. Bruce Fields if (delegated_inode) { 40155a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4016b21996e3SJ. Bruce Fields if (!error) 4017b21996e3SJ. Bruce Fields goto retry_deleg; 4018b21996e3SJ. Bruce Fields } 4019f5beed75SAl Viro mnt_drop_write(path.mnt); 40201da177e4SLinus Torvalds exit1: 4021f5beed75SAl Viro path_put(&path); 40225d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40235d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40245d18f813SJeff Layton inode = NULL; 40255d18f813SJeff Layton goto retry; 40265d18f813SJeff Layton } 4027da2f1362SChristoph Hellwig putname(name); 40281da177e4SLinus Torvalds return error; 40291da177e4SLinus Torvalds 40301da177e4SLinus Torvalds slashes: 4031b18825a7SDavid Howells if (d_is_negative(dentry)) 4032b18825a7SDavid Howells error = -ENOENT; 403344b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4034b18825a7SDavid Howells error = -EISDIR; 4035b18825a7SDavid Howells else 4036b18825a7SDavid Howells error = -ENOTDIR; 40371da177e4SLinus Torvalds goto exit2; 40381da177e4SLinus Torvalds } 40391da177e4SLinus Torvalds 40402e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40415590ff0dSUlrich Drepper { 40425590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40435590ff0dSUlrich Drepper return -EINVAL; 40445590ff0dSUlrich Drepper 40455590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40465590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40475590ff0dSUlrich Drepper 4048da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40495590ff0dSUlrich Drepper } 40505590ff0dSUlrich Drepper 40513480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40525590ff0dSUlrich Drepper { 4053da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40545590ff0dSUlrich Drepper } 40555590ff0dSUlrich Drepper 4056db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40571da177e4SLinus Torvalds { 4058a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40591da177e4SLinus Torvalds 40601da177e4SLinus Torvalds if (error) 40611da177e4SLinus Torvalds return error; 40621da177e4SLinus Torvalds 4063acfa4380SAl Viro if (!dir->i_op->symlink) 40641da177e4SLinus Torvalds return -EPERM; 40651da177e4SLinus Torvalds 40661da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40671da177e4SLinus Torvalds if (error) 40681da177e4SLinus Torvalds return error; 40691da177e4SLinus Torvalds 40701da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4071a74574aaSStephen Smalley if (!error) 4072f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40731da177e4SLinus Torvalds return error; 40741da177e4SLinus Torvalds } 40754d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40761da177e4SLinus Torvalds 4077b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4078b724e846SDominik Brodowski const char __user *newname) 40791da177e4SLinus Torvalds { 40802ad94ae6SAl Viro int error; 408191a27b2aSJeff Layton struct filename *from; 40826902d925SDave Hansen struct dentry *dentry; 4083dae6ad8fSAl Viro struct path path; 4084f46d3567SJeff Layton unsigned int lookup_flags = 0; 40851da177e4SLinus Torvalds 40861da177e4SLinus Torvalds from = getname(oldname); 40871da177e4SLinus Torvalds if (IS_ERR(from)) 40881da177e4SLinus Torvalds return PTR_ERR(from); 4089f46d3567SJeff Layton retry: 4090f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40911da177e4SLinus Torvalds error = PTR_ERR(dentry); 40926902d925SDave Hansen if (IS_ERR(dentry)) 4093dae6ad8fSAl Viro goto out_putname; 40946902d925SDave Hansen 409591a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4096a8104a9fSAl Viro if (!error) 409791a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4098921a1650SAl Viro done_path_create(&path, dentry); 4099f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4100f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4101f46d3567SJeff Layton goto retry; 4102f46d3567SJeff Layton } 41036902d925SDave Hansen out_putname: 41041da177e4SLinus Torvalds putname(from); 41051da177e4SLinus Torvalds return error; 41061da177e4SLinus Torvalds } 41071da177e4SLinus Torvalds 4108b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4109b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4110b724e846SDominik Brodowski { 4111b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4112b724e846SDominik Brodowski } 4113b724e846SDominik Brodowski 41143480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41155590ff0dSUlrich Drepper { 4116b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 41175590ff0dSUlrich Drepper } 41185590ff0dSUlrich Drepper 4119146a8595SJ. Bruce Fields /** 4120146a8595SJ. Bruce Fields * vfs_link - create a new link 4121146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4122146a8595SJ. Bruce Fields * @dir: new parent 4123146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4124146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4125146a8595SJ. Bruce Fields * 4126146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4127146a8595SJ. Bruce Fields * 4128146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4129146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4130146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4131146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4132146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4133146a8595SJ. Bruce Fields * 4134146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4135146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4136146a8595SJ. Bruce Fields * to be NFS exported. 4137146a8595SJ. Bruce Fields */ 4138146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41391da177e4SLinus Torvalds { 41401da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41418de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41421da177e4SLinus Torvalds int error; 41431da177e4SLinus Torvalds 41441da177e4SLinus Torvalds if (!inode) 41451da177e4SLinus Torvalds return -ENOENT; 41461da177e4SLinus Torvalds 4147a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41481da177e4SLinus Torvalds if (error) 41491da177e4SLinus Torvalds return error; 41501da177e4SLinus Torvalds 41511da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41521da177e4SLinus Torvalds return -EXDEV; 41531da177e4SLinus Torvalds 41541da177e4SLinus Torvalds /* 41551da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41561da177e4SLinus Torvalds */ 41571da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41581da177e4SLinus Torvalds return -EPERM; 41590bd23d09SEric W. Biederman /* 41600bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41610bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41620bd23d09SEric W. Biederman * the vfs. 41630bd23d09SEric W. Biederman */ 41640bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41650bd23d09SEric W. Biederman return -EPERM; 4166acfa4380SAl Viro if (!dir->i_op->link) 41671da177e4SLinus Torvalds return -EPERM; 41687e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41691da177e4SLinus Torvalds return -EPERM; 41701da177e4SLinus Torvalds 41711da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41721da177e4SLinus Torvalds if (error) 41731da177e4SLinus Torvalds return error; 41741da177e4SLinus Torvalds 41755955102cSAl Viro inode_lock(inode); 4176aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4177f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4178aae8a97dSAneesh Kumar K.V error = -ENOENT; 41798de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41808de52778SAl Viro error = -EMLINK; 4181146a8595SJ. Bruce Fields else { 4182146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4183146a8595SJ. Bruce Fields if (!error) 41841da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4185146a8595SJ. Bruce Fields } 4186f4e0c30cSAl Viro 4187f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4188f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4189f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4190f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4191f4e0c30cSAl Viro } 41925955102cSAl Viro inode_unlock(inode); 4193e31e14ecSStephen Smalley if (!error) 41947e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41951da177e4SLinus Torvalds return error; 41961da177e4SLinus Torvalds } 41974d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41981da177e4SLinus Torvalds 41991da177e4SLinus Torvalds /* 42001da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42011da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42021da177e4SLinus Torvalds * newname. --KAB 42031da177e4SLinus Torvalds * 42041da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42051da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42061da177e4SLinus Torvalds * and other special files. --ADM 42071da177e4SLinus Torvalds */ 420846ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 420946ea89ebSDominik Brodowski const char __user *newname, int flags) 42101da177e4SLinus Torvalds { 42111da177e4SLinus Torvalds struct dentry *new_dentry; 4212dae6ad8fSAl Viro struct path old_path, new_path; 4213146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 421411a7b371SAneesh Kumar K.V int how = 0; 42151da177e4SLinus Torvalds int error; 42161da177e4SLinus Torvalds 421711a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4218c04030e1SUlrich Drepper return -EINVAL; 421911a7b371SAneesh Kumar K.V /* 4220f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4221f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4222f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 422311a7b371SAneesh Kumar K.V */ 4224f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4225f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4226f0cc6ffbSLinus Torvalds return -ENOENT; 422711a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4228f0cc6ffbSLinus Torvalds } 4229c04030e1SUlrich Drepper 423011a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 423111a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4232442e31caSJeff Layton retry: 423311a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42341da177e4SLinus Torvalds if (error) 42352ad94ae6SAl Viro return error; 42362ad94ae6SAl Viro 4237442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4238442e31caSJeff Layton (how & LOOKUP_REVAL)); 42391da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42406902d925SDave Hansen if (IS_ERR(new_dentry)) 4241dae6ad8fSAl Viro goto out; 4242dae6ad8fSAl Viro 4243dae6ad8fSAl Viro error = -EXDEV; 4244dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4245dae6ad8fSAl Viro goto out_dput; 4246800179c9SKees Cook error = may_linkat(&old_path); 4247800179c9SKees Cook if (unlikely(error)) 4248800179c9SKees Cook goto out_dput; 4249dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4250be6d3e56SKentaro Takeda if (error) 4251a8104a9fSAl Viro goto out_dput; 4252146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 425375c3f29dSDave Hansen out_dput: 4254921a1650SAl Viro done_path_create(&new_path, new_dentry); 4255146a8595SJ. Bruce Fields if (delegated_inode) { 4256146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4257d22e6338SOleg Drokin if (!error) { 4258d22e6338SOleg Drokin path_put(&old_path); 4259146a8595SJ. Bruce Fields goto retry; 4260146a8595SJ. Bruce Fields } 4261d22e6338SOleg Drokin } 4262442e31caSJeff Layton if (retry_estale(error, how)) { 4263d22e6338SOleg Drokin path_put(&old_path); 4264442e31caSJeff Layton how |= LOOKUP_REVAL; 4265442e31caSJeff Layton goto retry; 4266442e31caSJeff Layton } 42671da177e4SLinus Torvalds out: 42682d8f3038SAl Viro path_put(&old_path); 42691da177e4SLinus Torvalds 42701da177e4SLinus Torvalds return error; 42711da177e4SLinus Torvalds } 42721da177e4SLinus Torvalds 427346ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 427446ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 427546ea89ebSDominik Brodowski { 427646ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 427746ea89ebSDominik Brodowski } 427846ea89ebSDominik Brodowski 42793480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42805590ff0dSUlrich Drepper { 428146ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42825590ff0dSUlrich Drepper } 42835590ff0dSUlrich Drepper 4284bc27027aSMiklos Szeredi /** 4285bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4286bc27027aSMiklos Szeredi * @old_dir: parent of source 4287bc27027aSMiklos Szeredi * @old_dentry: source 4288bc27027aSMiklos Szeredi * @new_dir: parent of destination 4289bc27027aSMiklos Szeredi * @new_dentry: destination 4290bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4291520c8b16SMiklos Szeredi * @flags: rename flags 4292bc27027aSMiklos Szeredi * 4293bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4294bc27027aSMiklos Szeredi * 4295bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4296bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4297bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4298bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4299bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4300bc27027aSMiklos Szeredi * so. 4301bc27027aSMiklos Szeredi * 4302bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4303bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4304bc27027aSMiklos Szeredi * to be NFS exported. 4305bc27027aSMiklos Szeredi * 43061da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43071da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43081da177e4SLinus Torvalds * Problems: 43090117d427SMauro Carvalho Chehab * 4310d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43111da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43121da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4313a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43141da177e4SLinus Torvalds * story. 43156cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43166cedba89SJ. Bruce Fields * and source (if it is not a directory). 43171b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43181da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43191da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4320a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43211da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43221da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43231da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4324a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43251da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43261da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43271da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4328e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43291b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43301da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4331c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43321da177e4SLinus Torvalds * locking]. 43331da177e4SLinus Torvalds */ 43341da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43358e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4336520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43371da177e4SLinus Torvalds { 43381da177e4SLinus Torvalds int error; 4339bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4340bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4341bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4342da1ce067SMiklos Szeredi bool new_is_dir = false; 4343da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 434449d31c2fSAl Viro struct name_snapshot old_name; 43451da177e4SLinus Torvalds 43468d3e2936SMiklos Szeredi if (source == target) 43471da177e4SLinus Torvalds return 0; 43481da177e4SLinus Torvalds 43491da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43501da177e4SLinus Torvalds if (error) 43511da177e4SLinus Torvalds return error; 43521da177e4SLinus Torvalds 4353da1ce067SMiklos Szeredi if (!target) { 4354a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4355da1ce067SMiklos Szeredi } else { 4356da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4357da1ce067SMiklos Szeredi 4358da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43591da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4360da1ce067SMiklos Szeredi else 4361da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4362da1ce067SMiklos Szeredi } 43631da177e4SLinus Torvalds if (error) 43641da177e4SLinus Torvalds return error; 43651da177e4SLinus Torvalds 43662773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43671da177e4SLinus Torvalds return -EPERM; 43681da177e4SLinus Torvalds 4369bc27027aSMiklos Szeredi /* 4370bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4371bc27027aSMiklos Szeredi * we'll need to flip '..'. 4372bc27027aSMiklos Szeredi */ 4373da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4374da1ce067SMiklos Szeredi if (is_dir) { 4375bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4376bc27027aSMiklos Szeredi if (error) 4377bc27027aSMiklos Szeredi return error; 4378bc27027aSMiklos Szeredi } 4379da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4380da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4381da1ce067SMiklos Szeredi if (error) 4382da1ce067SMiklos Szeredi return error; 4383da1ce067SMiklos Szeredi } 4384da1ce067SMiklos Szeredi } 43850eeca283SRobert Love 43860b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43870b3974ebSMiklos Szeredi flags); 4388bc27027aSMiklos Szeredi if (error) 4389bc27027aSMiklos Szeredi return error; 4390bc27027aSMiklos Szeredi 439149d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4392bc27027aSMiklos Szeredi dget(new_dentry); 4393da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4394bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4395bc27027aSMiklos Szeredi else if (target) 43965955102cSAl Viro inode_lock(target); 4397bc27027aSMiklos Szeredi 4398bc27027aSMiklos Szeredi error = -EBUSY; 43997af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4400bc27027aSMiklos Szeredi goto out; 4401bc27027aSMiklos Szeredi 4402da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4403bc27027aSMiklos Szeredi error = -EMLINK; 4404da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4405bc27027aSMiklos Szeredi goto out; 4406da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4407da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4408da1ce067SMiklos Szeredi goto out; 4409da1ce067SMiklos Szeredi } 4410da1ce067SMiklos Szeredi if (!is_dir) { 4411bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4412bc27027aSMiklos Szeredi if (error) 4413bc27027aSMiklos Szeredi goto out; 4414da1ce067SMiklos Szeredi } 4415da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4416bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4417bc27027aSMiklos Szeredi if (error) 4418bc27027aSMiklos Szeredi goto out; 4419bc27027aSMiklos Szeredi } 4420520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4421520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4422bc27027aSMiklos Szeredi if (error) 4423bc27027aSMiklos Szeredi goto out; 4424bc27027aSMiklos Szeredi 4425da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44268767712fSAl Viro if (is_dir) { 44278767712fSAl Viro shrink_dcache_parent(new_dentry); 4428bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 44298767712fSAl Viro } 4430bc27027aSMiklos Szeredi dont_mount(new_dentry); 44318ed936b5SEric W. Biederman detach_mounts(new_dentry); 4432bc27027aSMiklos Szeredi } 4433da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4434da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4435bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4436da1ce067SMiklos Szeredi else 4437da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4438da1ce067SMiklos Szeredi } 4439bc27027aSMiklos Szeredi out: 4440da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4441bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4442bc27027aSMiklos Szeredi else if (target) 44435955102cSAl Viro inode_unlock(target); 4444bc27027aSMiklos Szeredi dput(new_dentry); 4445da1ce067SMiklos Szeredi if (!error) { 4446f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4447da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4448da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4449f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4450da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4451da1ce067SMiklos Szeredi } 4452da1ce067SMiklos Szeredi } 445349d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44540eeca283SRobert Love 44551da177e4SLinus Torvalds return error; 44561da177e4SLinus Torvalds } 44574d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44581da177e4SLinus Torvalds 4459ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4460ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 44611da177e4SLinus Torvalds { 44621da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44631da177e4SLinus Torvalds struct dentry *trap; 4464f5beed75SAl Viro struct path old_path, new_path; 4465f5beed75SAl Viro struct qstr old_last, new_last; 4466f5beed75SAl Viro int old_type, new_type; 44678e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 446891a27b2aSJeff Layton struct filename *from; 446991a27b2aSJeff Layton struct filename *to; 4470f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4471c6a94284SJeff Layton bool should_retry = false; 44722ad94ae6SAl Viro int error; 4473520c8b16SMiklos Szeredi 44740d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4475da1ce067SMiklos Szeredi return -EINVAL; 4476da1ce067SMiklos Szeredi 44770d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44780d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4479520c8b16SMiklos Szeredi return -EINVAL; 4480520c8b16SMiklos Szeredi 44810d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44820d7a8555SMiklos Szeredi return -EPERM; 44830d7a8555SMiklos Szeredi 4484f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4485f5beed75SAl Viro target_flags = 0; 4486f5beed75SAl Viro 4487c6a94284SJeff Layton retry: 4488c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4489c1d4dd27SAl Viro &old_path, &old_last, &old_type); 449091a27b2aSJeff Layton if (IS_ERR(from)) { 449191a27b2aSJeff Layton error = PTR_ERR(from); 44921da177e4SLinus Torvalds goto exit; 449391a27b2aSJeff Layton } 44941da177e4SLinus Torvalds 4495c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4496c1d4dd27SAl Viro &new_path, &new_last, &new_type); 449791a27b2aSJeff Layton if (IS_ERR(to)) { 449891a27b2aSJeff Layton error = PTR_ERR(to); 44991da177e4SLinus Torvalds goto exit1; 450091a27b2aSJeff Layton } 45011da177e4SLinus Torvalds 45021da177e4SLinus Torvalds error = -EXDEV; 4503f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45041da177e4SLinus Torvalds goto exit2; 45051da177e4SLinus Torvalds 45061da177e4SLinus Torvalds error = -EBUSY; 4507f5beed75SAl Viro if (old_type != LAST_NORM) 45081da177e4SLinus Torvalds goto exit2; 45091da177e4SLinus Torvalds 45100a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45110a7c3937SMiklos Szeredi error = -EEXIST; 4512f5beed75SAl Viro if (new_type != LAST_NORM) 45131da177e4SLinus Torvalds goto exit2; 45141da177e4SLinus Torvalds 4515f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4516c30dabfeSJan Kara if (error) 4517c30dabfeSJan Kara goto exit2; 4518c30dabfeSJan Kara 45198e6d782cSJ. Bruce Fields retry_deleg: 4520f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45211da177e4SLinus Torvalds 4522f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45231da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45241da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45251da177e4SLinus Torvalds goto exit3; 45261da177e4SLinus Torvalds /* source must exist */ 45271da177e4SLinus Torvalds error = -ENOENT; 4528b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45291da177e4SLinus Torvalds goto exit4; 4530f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45311da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45321da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45331da177e4SLinus Torvalds goto exit4; 45340a7c3937SMiklos Szeredi error = -EEXIST; 45350a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45360a7c3937SMiklos Szeredi goto exit5; 4537da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4538da1ce067SMiklos Szeredi error = -ENOENT; 4539da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4540da1ce067SMiklos Szeredi goto exit5; 4541da1ce067SMiklos Szeredi 4542da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4543da1ce067SMiklos Szeredi error = -ENOTDIR; 4544f5beed75SAl Viro if (new_last.name[new_last.len]) 4545da1ce067SMiklos Szeredi goto exit5; 4546da1ce067SMiklos Szeredi } 4547da1ce067SMiklos Szeredi } 45480a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45490a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45500a7c3937SMiklos Szeredi error = -ENOTDIR; 4551f5beed75SAl Viro if (old_last.name[old_last.len]) 45520a7c3937SMiklos Szeredi goto exit5; 4553f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45540a7c3937SMiklos Szeredi goto exit5; 45550a7c3937SMiklos Szeredi } 45560a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45570a7c3937SMiklos Szeredi error = -EINVAL; 45580a7c3937SMiklos Szeredi if (old_dentry == trap) 45590a7c3937SMiklos Szeredi goto exit5; 45601da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4561da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45621da177e4SLinus Torvalds error = -ENOTEMPTY; 45631da177e4SLinus Torvalds if (new_dentry == trap) 45641da177e4SLinus Torvalds goto exit5; 45651da177e4SLinus Torvalds 4566f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4567f5beed75SAl Viro &new_path, new_dentry, flags); 4568be6d3e56SKentaro Takeda if (error) 4569c30dabfeSJan Kara goto exit5; 4570f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4571f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4572520c8b16SMiklos Szeredi &delegated_inode, flags); 45731da177e4SLinus Torvalds exit5: 45741da177e4SLinus Torvalds dput(new_dentry); 45751da177e4SLinus Torvalds exit4: 45761da177e4SLinus Torvalds dput(old_dentry); 45771da177e4SLinus Torvalds exit3: 4578f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45798e6d782cSJ. Bruce Fields if (delegated_inode) { 45808e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45818e6d782cSJ. Bruce Fields if (!error) 45828e6d782cSJ. Bruce Fields goto retry_deleg; 45838e6d782cSJ. Bruce Fields } 4584f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45851da177e4SLinus Torvalds exit2: 4586c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4587c6a94284SJeff Layton should_retry = true; 4588f5beed75SAl Viro path_put(&new_path); 45892ad94ae6SAl Viro putname(to); 45901da177e4SLinus Torvalds exit1: 4591f5beed75SAl Viro path_put(&old_path); 45921da177e4SLinus Torvalds putname(from); 4593c6a94284SJeff Layton if (should_retry) { 4594c6a94284SJeff Layton should_retry = false; 4595c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4596c6a94284SJeff Layton goto retry; 4597c6a94284SJeff Layton } 45982ad94ae6SAl Viro exit: 45991da177e4SLinus Torvalds return error; 46001da177e4SLinus Torvalds } 46011da177e4SLinus Torvalds 4602ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4603ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4604ee81feb6SDominik Brodowski { 4605ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4606ee81feb6SDominik Brodowski } 4607ee81feb6SDominik Brodowski 4608520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4609520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4610520c8b16SMiklos Szeredi { 4611ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4612520c8b16SMiklos Szeredi } 4613520c8b16SMiklos Szeredi 4614a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46155590ff0dSUlrich Drepper { 4616ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46175590ff0dSUlrich Drepper } 46185590ff0dSUlrich Drepper 4619787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4620787fb6bcSMiklos Szeredi { 4621787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4622787fb6bcSMiklos Szeredi if (error) 4623787fb6bcSMiklos Szeredi return error; 4624787fb6bcSMiklos Szeredi 4625787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4626787fb6bcSMiklos Szeredi return -EPERM; 4627787fb6bcSMiklos Szeredi 4628787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4629787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4630787fb6bcSMiklos Szeredi } 4631787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4632787fb6bcSMiklos Szeredi 46335d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46341da177e4SLinus Torvalds { 46355d826c84SAl Viro int len = PTR_ERR(link); 46361da177e4SLinus Torvalds if (IS_ERR(link)) 46371da177e4SLinus Torvalds goto out; 46381da177e4SLinus Torvalds 46391da177e4SLinus Torvalds len = strlen(link); 46401da177e4SLinus Torvalds if (len > (unsigned) buflen) 46411da177e4SLinus Torvalds len = buflen; 46421da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46431da177e4SLinus Torvalds len = -EFAULT; 46441da177e4SLinus Torvalds out: 46451da177e4SLinus Torvalds return len; 46461da177e4SLinus Torvalds } 46471da177e4SLinus Torvalds 4648d60874cdSMiklos Szeredi /** 4649fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4650fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4651fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4652fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4653fd4a0edfSMiklos Szeredi * 4654fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4655fd4a0edfSMiklos Szeredi * 4656fd4a0edfSMiklos Szeredi * Does not call security hook. 4657fd4a0edfSMiklos Szeredi */ 4658fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4659fd4a0edfSMiklos Szeredi { 4660fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4661f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4662f2df5da6SAl Viro const char *link; 4663f2df5da6SAl Viro int res; 4664fd4a0edfSMiklos Szeredi 466576fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 466676fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 466776fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 466876fca90eSMiklos Szeredi 466976fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4670fd4a0edfSMiklos Szeredi return -EINVAL; 4671fd4a0edfSMiklos Szeredi 467276fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 467376fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 467476fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 467576fca90eSMiklos Szeredi } 467676fca90eSMiklos Szeredi 46774c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4678f2df5da6SAl Viro if (!link) { 4679f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4680f2df5da6SAl Viro if (IS_ERR(link)) 4681f2df5da6SAl Viro return PTR_ERR(link); 4682f2df5da6SAl Viro } 4683f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4684f2df5da6SAl Viro do_delayed_call(&done); 4685f2df5da6SAl Viro return res; 4686fd4a0edfSMiklos Szeredi } 4687fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46881da177e4SLinus Torvalds 4689d60874cdSMiklos Szeredi /** 4690d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4691d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4692d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4693d60874cdSMiklos Szeredi * 4694d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4695d60874cdSMiklos Szeredi * 4696d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4697d60874cdSMiklos Szeredi * 4698d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4699d60874cdSMiklos Szeredi */ 4700d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4701d60874cdSMiklos Szeredi { 4702d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4703d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4704d60874cdSMiklos Szeredi 4705d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4706d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4707d60874cdSMiklos Szeredi if (!res) 4708d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4709d60874cdSMiklos Szeredi } 4710d60874cdSMiklos Szeredi return res; 4711d60874cdSMiklos Szeredi } 4712d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4713d60874cdSMiklos Szeredi 47141da177e4SLinus Torvalds /* get the link contents into pagecache */ 47156b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4716fceef393SAl Viro struct delayed_call *callback) 47171da177e4SLinus Torvalds { 4718ebd09abbSDuane Griffin char *kaddr; 47191da177e4SLinus Torvalds struct page *page; 47206b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47216b255391SAl Viro 4722d3883d4fSAl Viro if (!dentry) { 4723d3883d4fSAl Viro page = find_get_page(mapping, 0); 4724d3883d4fSAl Viro if (!page) 47256b255391SAl Viro return ERR_PTR(-ECHILD); 4726d3883d4fSAl Viro if (!PageUptodate(page)) { 4727d3883d4fSAl Viro put_page(page); 4728d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4729d3883d4fSAl Viro } 4730d3883d4fSAl Viro } else { 4731090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47321da177e4SLinus Torvalds if (IS_ERR(page)) 47336fe6900eSNick Piggin return (char*)page; 4734d3883d4fSAl Viro } 4735fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 473621fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 473721fc61c7SAl Viro kaddr = page_address(page); 47386b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4739ebd09abbSDuane Griffin return kaddr; 47401da177e4SLinus Torvalds } 47411da177e4SLinus Torvalds 47426b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47431da177e4SLinus Torvalds 4744fceef393SAl Viro void page_put_link(void *arg) 47451da177e4SLinus Torvalds { 4746fceef393SAl Viro put_page(arg); 47471da177e4SLinus Torvalds } 47484d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47491da177e4SLinus Torvalds 4750aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4751aa80deabSAl Viro { 4752fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47536b255391SAl Viro int res = readlink_copy(buffer, buflen, 47546b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4755fceef393SAl Viro &done)); 4756fceef393SAl Viro do_delayed_call(&done); 4757aa80deabSAl Viro return res; 4758aa80deabSAl Viro } 4759aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4760aa80deabSAl Viro 476154566b2cSNick Piggin /* 476254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 476354566b2cSNick Piggin */ 476454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47651da177e4SLinus Torvalds { 47661da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47670adb25d2SKirill Korotaev struct page *page; 4768afddba49SNick Piggin void *fsdata; 4769beb497abSDmitriy Monakhov int err; 4770c718a975STetsuo Handa unsigned int flags = 0; 477154566b2cSNick Piggin if (nofs) 477254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47731da177e4SLinus Torvalds 47747e53cac4SNeilBrown retry: 4775afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 477654566b2cSNick Piggin flags, &page, &fsdata); 47771da177e4SLinus Torvalds if (err) 4778afddba49SNick Piggin goto fail; 4779afddba49SNick Piggin 478021fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4781afddba49SNick Piggin 4782afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4783afddba49SNick Piggin page, fsdata); 47841da177e4SLinus Torvalds if (err < 0) 47851da177e4SLinus Torvalds goto fail; 4786afddba49SNick Piggin if (err < len-1) 4787afddba49SNick Piggin goto retry; 4788afddba49SNick Piggin 47891da177e4SLinus Torvalds mark_inode_dirty(inode); 47901da177e4SLinus Torvalds return 0; 47911da177e4SLinus Torvalds fail: 47921da177e4SLinus Torvalds return err; 47931da177e4SLinus Torvalds } 47944d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47951da177e4SLinus Torvalds 47960adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47970adb25d2SKirill Korotaev { 47980adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4799c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48000adb25d2SKirill Korotaev } 48014d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48020adb25d2SKirill Korotaev 480392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48046b255391SAl Viro .get_link = page_get_link, 48051da177e4SLinus Torvalds }; 48061da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4807