11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 382a18da7aSGeorge Spelvin #include <linux/bitops.h> 391da177e4SLinus Torvalds #include <asm/uaccess.h> 401da177e4SLinus Torvalds 41e81e3f4dSEric Paris #include "internal.h" 42c7105365SAl Viro #include "mount.h" 43e81e3f4dSEric Paris 441da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 451da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 461da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 471da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 481da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 491da177e4SLinus Torvalds * 501da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 511da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 521da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 531da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 541da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 551da177e4SLinus Torvalds * the special cases of the former code. 561da177e4SLinus Torvalds * 571da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 581da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 591da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 601da177e4SLinus Torvalds * 611da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 621da177e4SLinus Torvalds * resolution to correspond with current state of the code. 631da177e4SLinus Torvalds * 641da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 651da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 661da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 671da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 681da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 691da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 701da177e4SLinus Torvalds */ 711da177e4SLinus Torvalds 721da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 731da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 741da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 751da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 761da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 771da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7825985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 791da177e4SLinus Torvalds * 801da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 811da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 821da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 831da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 841da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 851da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 861da177e4SLinus Torvalds * and in the old Linux semantics. 871da177e4SLinus Torvalds */ 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 901da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 911da177e4SLinus Torvalds * 921da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 931da177e4SLinus Torvalds */ 941da177e4SLinus Torvalds 951da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 961da177e4SLinus Torvalds * inside the path - always follow. 971da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 981da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 991da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1001da177e4SLinus Torvalds * otherwise - don't follow. 1011da177e4SLinus Torvalds * (applied in that order). 1021da177e4SLinus Torvalds * 1031da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1041da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1051da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1061da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1071da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds /* 1101da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 111a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1121da177e4SLinus Torvalds * any extra contention... 1131da177e4SLinus Torvalds */ 1141da177e4SLinus Torvalds 1151da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1161da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1171da177e4SLinus Torvalds * kernel data space before using them.. 1181da177e4SLinus Torvalds * 1191da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1201da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1211da177e4SLinus Torvalds */ 1227950e385SJeff Layton 123fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12491a27b2aSJeff Layton 12551f39a1fSDavid Drysdale struct filename * 12691a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12791a27b2aSJeff Layton { 12894b5d262SAl Viro struct filename *result; 1297950e385SJeff Layton char *kname; 13094b5d262SAl Viro int len; 1311da177e4SLinus Torvalds 1327ac86265SJeff Layton result = audit_reusename(filename); 1337ac86265SJeff Layton if (result) 1347ac86265SJeff Layton return result; 1357ac86265SJeff Layton 1367950e385SJeff Layton result = __getname(); 1373f9f0aa6SLinus Torvalds if (unlikely(!result)) 1384043cde8SEric Paris return ERR_PTR(-ENOMEM); 1391da177e4SLinus Torvalds 1407950e385SJeff Layton /* 1417950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1427950e385SJeff Layton * allocation 1437950e385SJeff Layton */ 144fd2f7cb5SAl Viro kname = (char *)result->iname; 14591a27b2aSJeff Layton result->name = kname; 1467950e385SJeff Layton 14794b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14891a27b2aSJeff Layton if (unlikely(len < 0)) { 14994b5d262SAl Viro __putname(result); 15094b5d262SAl Viro return ERR_PTR(len); 15191a27b2aSJeff Layton } 1523f9f0aa6SLinus Torvalds 1537950e385SJeff Layton /* 1547950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1557950e385SJeff Layton * separate struct filename so we can dedicate the entire 1567950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1577950e385SJeff Layton * userland. 1587950e385SJeff Layton */ 15994b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 160fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1617950e385SJeff Layton kname = (char *)result; 1627950e385SJeff Layton 163fd2f7cb5SAl Viro /* 164fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 165fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 166fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 167fd2f7cb5SAl Viro */ 168fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16994b5d262SAl Viro if (unlikely(!result)) { 17094b5d262SAl Viro __putname(kname); 17194b5d262SAl Viro return ERR_PTR(-ENOMEM); 1727950e385SJeff Layton } 1737950e385SJeff Layton result->name = kname; 17494b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17594b5d262SAl Viro if (unlikely(len < 0)) { 17694b5d262SAl Viro __putname(kname); 17794b5d262SAl Viro kfree(result); 17894b5d262SAl Viro return ERR_PTR(len); 17994b5d262SAl Viro } 18094b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18194b5d262SAl Viro __putname(kname); 18294b5d262SAl Viro kfree(result); 18394b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18494b5d262SAl Viro } 1857950e385SJeff Layton } 1867950e385SJeff Layton 18794b5d262SAl Viro result->refcnt = 1; 1883f9f0aa6SLinus Torvalds /* The empty path is special. */ 1893f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1903f9f0aa6SLinus Torvalds if (empty) 1911fa1e7f6SAndy Whitcroft *empty = 1; 19294b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19394b5d262SAl Viro putname(result); 19494b5d262SAl Viro return ERR_PTR(-ENOENT); 1951da177e4SLinus Torvalds } 19694b5d262SAl Viro } 1977950e385SJeff Layton 1987950e385SJeff Layton result->uptr = filename; 199c4ad8f98SLinus Torvalds result->aname = NULL; 2001da177e4SLinus Torvalds audit_getname(result); 2011da177e4SLinus Torvalds return result; 2023f9f0aa6SLinus Torvalds } 2033f9f0aa6SLinus Torvalds 20491a27b2aSJeff Layton struct filename * 20591a27b2aSJeff Layton getname(const char __user * filename) 206f52e0c11SAl Viro { 207f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 208f52e0c11SAl Viro } 209f52e0c11SAl Viro 210c4ad8f98SLinus Torvalds struct filename * 211c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 212c4ad8f98SLinus Torvalds { 213c4ad8f98SLinus Torvalds struct filename *result; 21408518549SPaul Moore int len = strlen(filename) + 1; 215c4ad8f98SLinus Torvalds 216c4ad8f98SLinus Torvalds result = __getname(); 217c4ad8f98SLinus Torvalds if (unlikely(!result)) 218c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 219c4ad8f98SLinus Torvalds 22008518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 221fd2f7cb5SAl Viro result->name = (char *)result->iname; 22208518549SPaul Moore } else if (len <= PATH_MAX) { 22308518549SPaul Moore struct filename *tmp; 22408518549SPaul Moore 22508518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22608518549SPaul Moore if (unlikely(!tmp)) { 22708518549SPaul Moore __putname(result); 22808518549SPaul Moore return ERR_PTR(-ENOMEM); 22908518549SPaul Moore } 23008518549SPaul Moore tmp->name = (char *)result; 23108518549SPaul Moore result = tmp; 23208518549SPaul Moore } else { 23308518549SPaul Moore __putname(result); 23408518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23508518549SPaul Moore } 23608518549SPaul Moore memcpy((char *)result->name, filename, len); 237c4ad8f98SLinus Torvalds result->uptr = NULL; 238c4ad8f98SLinus Torvalds result->aname = NULL; 23955422d0bSPaul Moore result->refcnt = 1; 240fd3522fdSPaul Moore audit_getname(result); 241c4ad8f98SLinus Torvalds 242c4ad8f98SLinus Torvalds return result; 243c4ad8f98SLinus Torvalds } 244c4ad8f98SLinus Torvalds 24591a27b2aSJeff Layton void putname(struct filename *name) 2461da177e4SLinus Torvalds { 24755422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24855422d0bSPaul Moore 24955422d0bSPaul Moore if (--name->refcnt > 0) 25055422d0bSPaul Moore return; 25155422d0bSPaul Moore 252fd2f7cb5SAl Viro if (name->name != name->iname) { 25355422d0bSPaul Moore __putname(name->name); 25455422d0bSPaul Moore kfree(name); 25555422d0bSPaul Moore } else 25655422d0bSPaul Moore __putname(name); 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 259e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 260e77819e5SLinus Torvalds { 26184635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 262e77819e5SLinus Torvalds struct posix_acl *acl; 263e77819e5SLinus Torvalds 264e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2653567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2663567866bSAl Viro if (!acl) 267e77819e5SLinus Torvalds return -EAGAIN; 2683567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2693567866bSAl Viro if (acl == ACL_NOT_CACHED) 270e77819e5SLinus Torvalds return -ECHILD; 271206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 272e77819e5SLinus Torvalds } 273e77819e5SLinus Torvalds 2742982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2754e34e719SChristoph Hellwig if (IS_ERR(acl)) 2764e34e719SChristoph Hellwig return PTR_ERR(acl); 277e77819e5SLinus Torvalds if (acl) { 278e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 279e77819e5SLinus Torvalds posix_acl_release(acl); 280e77819e5SLinus Torvalds return error; 281e77819e5SLinus Torvalds } 28284635d68SLinus Torvalds #endif 283e77819e5SLinus Torvalds 284e77819e5SLinus Torvalds return -EAGAIN; 285e77819e5SLinus Torvalds } 286e77819e5SLinus Torvalds 2875909ccaaSLinus Torvalds /* 288948409c7SAndreas Gruenbacher * This does the basic permission checking 2895909ccaaSLinus Torvalds */ 2907e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2915909ccaaSLinus Torvalds { 29226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2935909ccaaSLinus Torvalds 2948e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2955909ccaaSLinus Torvalds mode >>= 6; 2965909ccaaSLinus Torvalds else { 297e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2987e40145eSAl Viro int error = check_acl(inode, mask); 2995909ccaaSLinus Torvalds if (error != -EAGAIN) 3005909ccaaSLinus Torvalds return error; 3015909ccaaSLinus Torvalds } 3025909ccaaSLinus Torvalds 3035909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3045909ccaaSLinus Torvalds mode >>= 3; 3055909ccaaSLinus Torvalds } 3065909ccaaSLinus Torvalds 3075909ccaaSLinus Torvalds /* 3085909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3095909ccaaSLinus Torvalds */ 3109c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3115909ccaaSLinus Torvalds return 0; 3125909ccaaSLinus Torvalds return -EACCES; 3135909ccaaSLinus Torvalds } 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds /** 3161da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3171da177e4SLinus Torvalds * @inode: inode to check access rights for 3188fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3191da177e4SLinus Torvalds * 3201da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3211da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3221da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 323b74c79e9SNick Piggin * are used for other things. 324b74c79e9SNick Piggin * 325b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 326b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 327b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3281da177e4SLinus Torvalds */ 3292830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3301da177e4SLinus Torvalds { 3315909ccaaSLinus Torvalds int ret; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds /* 334948409c7SAndreas Gruenbacher * Do the basic permission checks. 3351da177e4SLinus Torvalds */ 3367e40145eSAl Viro ret = acl_permission_check(inode, mask); 3375909ccaaSLinus Torvalds if (ret != -EACCES) 3385909ccaaSLinus Torvalds return ret; 3391da177e4SLinus Torvalds 340d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 341d594e7ecSAl Viro /* DACs are overridable for directories */ 34223adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 343d594e7ecSAl Viro return 0; 344d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34623adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 347d594e7ecSAl Viro return 0; 348d594e7ecSAl Viro return -EACCES; 349d594e7ecSAl Viro } 3501da177e4SLinus Torvalds /* 3511da177e4SLinus Torvalds * Read/write DACs are always overridable. 352d594e7ecSAl Viro * Executable DACs are overridable when there is 353d594e7ecSAl Viro * at least one exec bit set. 3541da177e4SLinus Torvalds */ 355d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3571da177e4SLinus Torvalds return 0; 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds /* 3601da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3611da177e4SLinus Torvalds */ 3627ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 363d594e7ecSAl Viro if (mask == MAY_READ) 36423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3651da177e4SLinus Torvalds return 0; 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds return -EACCES; 3681da177e4SLinus Torvalds } 3694d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3701da177e4SLinus Torvalds 3713ddcd056SLinus Torvalds /* 3723ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3733ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3743ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3753ddcd056SLinus Torvalds * permission function, use the fast case". 3763ddcd056SLinus Torvalds */ 3773ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3783ddcd056SLinus Torvalds { 3793ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3803ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3813ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3823ddcd056SLinus Torvalds 3833ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3843ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3853ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3863ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3873ddcd056SLinus Torvalds } 3883ddcd056SLinus Torvalds return generic_permission(inode, mask); 3893ddcd056SLinus Torvalds } 3903ddcd056SLinus Torvalds 391cb23beb5SChristoph Hellwig /** 3920bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3930bdaea90SDavid Howells * @inode: Inode to check permission on 3940bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 395cb23beb5SChristoph Hellwig * 3960bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 397948409c7SAndreas Gruenbacher * 398948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4010bdaea90SDavid Howells * inode_permission(). 402cb23beb5SChristoph Hellwig */ 4030bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4041da177e4SLinus Torvalds { 405e6305c43SAl Viro int retval; 4061da177e4SLinus Torvalds 4073ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4081da177e4SLinus Torvalds /* 4091da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4101da177e4SLinus Torvalds */ 4111da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4121da177e4SLinus Torvalds return -EACCES; 4131da177e4SLinus Torvalds } 4141da177e4SLinus Torvalds 4153ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4161da177e4SLinus Torvalds if (retval) 4171da177e4SLinus Torvalds return retval; 4181da177e4SLinus Torvalds 41908ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 42008ce5f16SSerge E. Hallyn if (retval) 42108ce5f16SSerge E. Hallyn return retval; 42208ce5f16SSerge E. Hallyn 423d09ca739SEric Paris return security_inode_permission(inode, mask); 4241da177e4SLinus Torvalds } 425bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4261da177e4SLinus Torvalds 427f4d6ff89SAl Viro /** 4280bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4290bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 43055852635SRandy Dunlap * @inode: Inode to check permission on 4310bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4320bdaea90SDavid Howells * 4330bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4340bdaea90SDavid Howells */ 4350bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4360bdaea90SDavid Howells { 4370bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4380bdaea90SDavid Howells umode_t mode = inode->i_mode; 4390bdaea90SDavid Howells 4400bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4410bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4420bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4430bdaea90SDavid Howells return -EROFS; 4440bdaea90SDavid Howells } 4450bdaea90SDavid Howells return 0; 4460bdaea90SDavid Howells } 4470bdaea90SDavid Howells 4480bdaea90SDavid Howells /** 4490bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4500bdaea90SDavid Howells * @inode: Inode to check permission on 4510bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4520bdaea90SDavid Howells * 4530bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4540bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4550bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4560bdaea90SDavid Howells * 4570bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4580bdaea90SDavid Howells */ 4590bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4600bdaea90SDavid Howells { 4610bdaea90SDavid Howells int retval; 4620bdaea90SDavid Howells 4630bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4640bdaea90SDavid Howells if (retval) 4650bdaea90SDavid Howells return retval; 4660bdaea90SDavid Howells return __inode_permission(inode, mask); 4670bdaea90SDavid Howells } 4684d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4690bdaea90SDavid Howells 4700bdaea90SDavid Howells /** 4715dd784d0SJan Blunck * path_get - get a reference to a path 4725dd784d0SJan Blunck * @path: path to get the reference to 4735dd784d0SJan Blunck * 4745dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4755dd784d0SJan Blunck */ 476dcf787f3SAl Viro void path_get(const struct path *path) 4775dd784d0SJan Blunck { 4785dd784d0SJan Blunck mntget(path->mnt); 4795dd784d0SJan Blunck dget(path->dentry); 4805dd784d0SJan Blunck } 4815dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4825dd784d0SJan Blunck 4835dd784d0SJan Blunck /** 4841d957f9bSJan Blunck * path_put - put a reference to a path 4851d957f9bSJan Blunck * @path: path to put the reference to 4861d957f9bSJan Blunck * 4871d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4881d957f9bSJan Blunck */ 489dcf787f3SAl Viro void path_put(const struct path *path) 4901da177e4SLinus Torvalds { 4911d957f9bSJan Blunck dput(path->dentry); 4921d957f9bSJan Blunck mntput(path->mnt); 4931da177e4SLinus Torvalds } 4941d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4951da177e4SLinus Torvalds 496894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4971f55a6ecSAl Viro struct nameidata { 4981f55a6ecSAl Viro struct path path; 4991f55a6ecSAl Viro struct qstr last; 5001f55a6ecSAl Viro struct path root; 5011f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5021f55a6ecSAl Viro unsigned int flags; 5039883d185SAl Viro unsigned seq, m_seq; 5041f55a6ecSAl Viro int last_type; 5051f55a6ecSAl Viro unsigned depth; 506756daf26SNeilBrown int total_link_count; 507697fc6caSAl Viro struct saved { 508697fc6caSAl Viro struct path link; 509fceef393SAl Viro struct delayed_call done; 510697fc6caSAl Viro const char *name; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5139883d185SAl Viro struct filename *name; 5149883d185SAl Viro struct nameidata *saved; 515fceef393SAl Viro struct inode *link_inode; 5169883d185SAl Viro unsigned root_seq; 5179883d185SAl Viro int dfd; 5181f55a6ecSAl Viro }; 5191f55a6ecSAl Viro 5209883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 521894bc8c4SAl Viro { 522756daf26SNeilBrown struct nameidata *old = current->nameidata; 523756daf26SNeilBrown p->stack = p->internal; 524c8a53ee5SAl Viro p->dfd = dfd; 525c8a53ee5SAl Viro p->name = name; 526756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5279883d185SAl Viro p->saved = old; 528756daf26SNeilBrown current->nameidata = p; 529894bc8c4SAl Viro } 530894bc8c4SAl Viro 5319883d185SAl Viro static void restore_nameidata(void) 532894bc8c4SAl Viro { 5339883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 534756daf26SNeilBrown 535756daf26SNeilBrown current->nameidata = old; 536756daf26SNeilBrown if (old) 537756daf26SNeilBrown old->total_link_count = now->total_link_count; 538e1a63bbcSAl Viro if (now->stack != now->internal) 539756daf26SNeilBrown kfree(now->stack); 540894bc8c4SAl Viro } 541894bc8c4SAl Viro 542894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 543894bc8c4SAl Viro { 544bc40aee0SAl Viro struct saved *p; 545bc40aee0SAl Viro 546bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 547bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 548bc40aee0SAl Viro GFP_ATOMIC); 549bc40aee0SAl Viro if (unlikely(!p)) 550bc40aee0SAl Viro return -ECHILD; 551bc40aee0SAl Viro } else { 552bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 553894bc8c4SAl Viro GFP_KERNEL); 554894bc8c4SAl Viro if (unlikely(!p)) 555894bc8c4SAl Viro return -ENOMEM; 556bc40aee0SAl Viro } 557894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 558894bc8c4SAl Viro nd->stack = p; 559894bc8c4SAl Viro return 0; 560894bc8c4SAl Viro } 561894bc8c4SAl Viro 562397d425dSEric W. Biederman /** 563397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 564397d425dSEric W. Biederman * @path: nameidate to verify 565397d425dSEric W. Biederman * 566397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 567397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 568397d425dSEric W. Biederman */ 569397d425dSEric W. Biederman static bool path_connected(const struct path *path) 570397d425dSEric W. Biederman { 571397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 572397d425dSEric W. Biederman 573397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 574397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 575397d425dSEric W. Biederman return true; 576397d425dSEric W. Biederman 577397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 578397d425dSEric W. Biederman } 579397d425dSEric W. Biederman 580894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 581894bc8c4SAl Viro { 582da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 583894bc8c4SAl Viro return 0; 584894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 585894bc8c4SAl Viro return 0; 586894bc8c4SAl Viro return __nd_alloc_stack(nd); 587894bc8c4SAl Viro } 588894bc8c4SAl Viro 5897973387aSAl Viro static void drop_links(struct nameidata *nd) 5907973387aSAl Viro { 5917973387aSAl Viro int i = nd->depth; 5927973387aSAl Viro while (i--) { 5937973387aSAl Viro struct saved *last = nd->stack + i; 594fceef393SAl Viro do_delayed_call(&last->done); 595fceef393SAl Viro clear_delayed_call(&last->done); 5967973387aSAl Viro } 5977973387aSAl Viro } 5987973387aSAl Viro 5997973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6007973387aSAl Viro { 6017973387aSAl Viro drop_links(nd); 6027973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6037973387aSAl Viro int i; 6047973387aSAl Viro path_put(&nd->path); 6057973387aSAl Viro for (i = 0; i < nd->depth; i++) 6067973387aSAl Viro path_put(&nd->stack[i].link); 607102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 608102b8af2SAl Viro path_put(&nd->root); 609102b8af2SAl Viro nd->root.mnt = NULL; 610102b8af2SAl Viro } 6117973387aSAl Viro } else { 6127973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6137973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6147973387aSAl Viro nd->root.mnt = NULL; 6157973387aSAl Viro rcu_read_unlock(); 6167973387aSAl Viro } 6177973387aSAl Viro nd->depth = 0; 6187973387aSAl Viro } 6197973387aSAl Viro 6207973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6217973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6227973387aSAl Viro struct path *path, unsigned seq) 6237973387aSAl Viro { 6247973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6257973387aSAl Viro if (unlikely(res)) { 6267973387aSAl Viro if (res > 0) 6277973387aSAl Viro path->mnt = NULL; 6287973387aSAl Viro path->dentry = NULL; 6297973387aSAl Viro return false; 6307973387aSAl Viro } 6317973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6327973387aSAl Viro path->dentry = NULL; 6337973387aSAl Viro return false; 6347973387aSAl Viro } 6357973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6367973387aSAl Viro } 6377973387aSAl Viro 6387973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6397973387aSAl Viro { 6407973387aSAl Viro int i; 6417973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6427973387aSAl Viro struct saved *last = nd->stack + i; 6437973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6447973387aSAl Viro drop_links(nd); 6457973387aSAl Viro nd->depth = i + 1; 6467973387aSAl Viro return false; 6477973387aSAl Viro } 6487973387aSAl Viro } 6497973387aSAl Viro return true; 6507973387aSAl Viro } 6517973387aSAl Viro 65219660af7SAl Viro /* 65331e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65419660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65519660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65657e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65719660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65819660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65919660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66019660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66131e6b01fSNick Piggin */ 66231e6b01fSNick Piggin 66331e6b01fSNick Piggin /** 66419660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66519660af7SAl Viro * @nd: nameidata pathwalk data 66619660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6676e9918b7SAl Viro * @seq: seq number to check dentry against 66839191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 66931e6b01fSNick Piggin * 67019660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 67119660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 67219660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6737973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6747973387aSAl Viro * terminate_walk(). 67531e6b01fSNick Piggin */ 6766e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 67731e6b01fSNick Piggin { 67831e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 67931e6b01fSNick Piggin 68031e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 681e5c832d5SLinus Torvalds 682e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6837973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6847973387aSAl Viro goto out2; 6857973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6867973387aSAl Viro goto out2; 6877973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6887973387aSAl Viro goto out1; 68948a066e7SAl Viro 69015570086SLinus Torvalds /* 69115570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 69215570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 69315570086SLinus Torvalds * 69415570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 69515570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 69615570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 69715570086SLinus Torvalds * since we checked the sequence number of the parent after we got 69815570086SLinus Torvalds * the child sequence number. So we know the parent must still 69915570086SLinus Torvalds * be valid if the child sequence number is still valid. 70015570086SLinus Torvalds */ 70119660af7SAl Viro if (!dentry) { 702e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 703e5c832d5SLinus Torvalds goto out; 70419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 70519660af7SAl Viro } else { 706e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 707e5c832d5SLinus Torvalds goto out; 7086e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 709e5c832d5SLinus Torvalds goto drop_dentry; 71019660af7SAl Viro } 711e5c832d5SLinus Torvalds 712e5c832d5SLinus Torvalds /* 713e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 714e5c832d5SLinus Torvalds * still valid and get it if required. 715e5c832d5SLinus Torvalds */ 716e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7175a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7185a8d87e8SAl Viro rcu_read_unlock(); 7195a8d87e8SAl Viro dput(dentry); 7205a8d87e8SAl Viro return -ECHILD; 7217973387aSAl Viro } 72231e6b01fSNick Piggin } 72331e6b01fSNick Piggin 7248b61e74fSAl Viro rcu_read_unlock(); 72531e6b01fSNick Piggin return 0; 72619660af7SAl Viro 727e5c832d5SLinus Torvalds drop_dentry: 7288b61e74fSAl Viro rcu_read_unlock(); 729e5c832d5SLinus Torvalds dput(dentry); 730d0d27277SLinus Torvalds goto drop_root_mnt; 7317973387aSAl Viro out2: 7327973387aSAl Viro nd->path.mnt = NULL; 7337973387aSAl Viro out1: 7347973387aSAl Viro nd->path.dentry = NULL; 735e5c832d5SLinus Torvalds out: 7368b61e74fSAl Viro rcu_read_unlock(); 737d0d27277SLinus Torvalds drop_root_mnt: 738d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 739d0d27277SLinus Torvalds nd->root.mnt = NULL; 74031e6b01fSNick Piggin return -ECHILD; 74131e6b01fSNick Piggin } 74231e6b01fSNick Piggin 7437973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7447973387aSAl Viro { 7457973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7467973387aSAl Viro drop_links(nd); 7477973387aSAl Viro nd->depth = 0; 7487973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7497973387aSAl Viro nd->path.mnt = NULL; 7507973387aSAl Viro nd->path.dentry = NULL; 7517973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7527973387aSAl Viro nd->root.mnt = NULL; 7537973387aSAl Viro rcu_read_unlock(); 7547973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7557973387aSAl Viro return 0; 7567973387aSAl Viro } 7577973387aSAl Viro path_put(link); 7587973387aSAl Viro return -ECHILD; 7597973387aSAl Viro } 7607973387aSAl Viro 7614ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76234286d66SNick Piggin { 7634ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 76434286d66SNick Piggin } 76534286d66SNick Piggin 7669f1fafeeSAl Viro /** 7679f1fafeeSAl Viro * complete_walk - successful completion of path walk 7689f1fafeeSAl Viro * @nd: pointer nameidata 76939159de2SJeff Layton * 7709f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7719f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7729f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7739f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7749f1fafeeSAl Viro * need to drop nd->path. 77539159de2SJeff Layton */ 7769f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77739159de2SJeff Layton { 77816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77939159de2SJeff Layton int status; 78039159de2SJeff Layton 7819f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7829f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7839f1fafeeSAl Viro nd->root.mnt = NULL; 7846e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 78548a066e7SAl Viro return -ECHILD; 78648a066e7SAl Viro } 7879f1fafeeSAl Viro 78816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78939159de2SJeff Layton return 0; 79039159de2SJeff Layton 791ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79216c2cd71SAl Viro return 0; 79316c2cd71SAl Viro 794ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79539159de2SJeff Layton if (status > 0) 79639159de2SJeff Layton return 0; 79739159de2SJeff Layton 79816c2cd71SAl Viro if (!status) 79939159de2SJeff Layton status = -ESTALE; 80016c2cd71SAl Viro 80139159de2SJeff Layton return status; 80239159de2SJeff Layton } 80339159de2SJeff Layton 80418d8c860SAl Viro static void set_root(struct nameidata *nd) 8052a737871SAl Viro { 80631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8079e6697e2SAl Viro 8089e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8098f47a016SAl Viro unsigned seq; 810c28cc364SNick Piggin 811c28cc364SNick Piggin do { 812c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81331e6b01fSNick Piggin nd->root = fs->root; 8148f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 815c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8169e6697e2SAl Viro } else { 8179e6697e2SAl Viro get_fs_root(fs, &nd->root); 8189e6697e2SAl Viro } 81931e6b01fSNick Piggin } 82031e6b01fSNick Piggin 8211d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 822051d3812SIan Kent { 823051d3812SIan Kent dput(path->dentry); 8244ac91378SJan Blunck if (path->mnt != nd->path.mnt) 825051d3812SIan Kent mntput(path->mnt); 826051d3812SIan Kent } 827051d3812SIan Kent 8287b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8297b9337aaSNick Piggin struct nameidata *nd) 830051d3812SIan Kent { 83131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8324ac91378SJan Blunck dput(nd->path.dentry); 83331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8344ac91378SJan Blunck mntput(nd->path.mnt); 8359a229683SHuang Shijie } 83631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8374ac91378SJan Blunck nd->path.dentry = path->dentry; 838051d3812SIan Kent } 839051d3812SIan Kent 840248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 841248fb5b9SAl Viro { 842248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 843248fb5b9SAl Viro struct dentry *d; 844248fb5b9SAl Viro nd->path = nd->root; 845248fb5b9SAl Viro d = nd->path.dentry; 846248fb5b9SAl Viro nd->inode = d->d_inode; 847248fb5b9SAl Viro nd->seq = nd->root_seq; 848248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 849248fb5b9SAl Viro return -ECHILD; 850248fb5b9SAl Viro } else { 851248fb5b9SAl Viro path_put(&nd->path); 852248fb5b9SAl Viro nd->path = nd->root; 853248fb5b9SAl Viro path_get(&nd->path); 854248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 855248fb5b9SAl Viro } 856248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 857248fb5b9SAl Viro return 0; 858248fb5b9SAl Viro } 859248fb5b9SAl Viro 860b5fb63c1SChristoph Hellwig /* 8616b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 862b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 863b5fb63c1SChristoph Hellwig */ 8646e77137bSAl Viro void nd_jump_link(struct path *path) 865b5fb63c1SChristoph Hellwig { 8666e77137bSAl Viro struct nameidata *nd = current->nameidata; 867b5fb63c1SChristoph Hellwig path_put(&nd->path); 868b5fb63c1SChristoph Hellwig 869b5fb63c1SChristoph Hellwig nd->path = *path; 870b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 871b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 872b5fb63c1SChristoph Hellwig } 873b5fb63c1SChristoph Hellwig 874b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 875574197e0SAl Viro { 87621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 877fceef393SAl Viro do_delayed_call(&last->done); 8786548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 879b9ff4429SAl Viro path_put(&last->link); 880574197e0SAl Viro } 881574197e0SAl Viro 882561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 883561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 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; 904800179c9SKees Cook 905800179c9SKees Cook if (!sysctl_protected_symlinks) 906800179c9SKees Cook return 0; 907800179c9SKees Cook 908800179c9SKees Cook /* Allowed if owner and follower match. */ 909fceef393SAl Viro inode = nd->link_inode; 91081abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 911800179c9SKees Cook return 0; 912800179c9SKees Cook 913800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 914aa65fa35SAl Viro parent = nd->inode; 915800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 916800179c9SKees Cook return 0; 917800179c9SKees Cook 918800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 91981abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 920800179c9SKees Cook return 0; 921800179c9SKees Cook 92231956502SAl Viro if (nd->flags & LOOKUP_RCU) 92331956502SAl Viro return -ECHILD; 92431956502SAl Viro 9251cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 926800179c9SKees Cook return -EACCES; 927800179c9SKees Cook } 928800179c9SKees Cook 929800179c9SKees Cook /** 930800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 931800179c9SKees Cook * @inode: the source inode to hardlink from 932800179c9SKees Cook * 933800179c9SKees Cook * Return false if at least one of the following conditions: 934800179c9SKees Cook * - inode is not a regular file 935800179c9SKees Cook * - inode is setuid 936800179c9SKees Cook * - inode is setgid and group-exec 937800179c9SKees Cook * - access failure for read and write 938800179c9SKees Cook * 939800179c9SKees Cook * Otherwise returns true. 940800179c9SKees Cook */ 941800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 942800179c9SKees Cook { 943800179c9SKees Cook umode_t mode = inode->i_mode; 944800179c9SKees Cook 945800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 946800179c9SKees Cook if (!S_ISREG(mode)) 947800179c9SKees Cook return false; 948800179c9SKees Cook 949800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 950800179c9SKees Cook if (mode & S_ISUID) 951800179c9SKees Cook return false; 952800179c9SKees Cook 953800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 954800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 955800179c9SKees Cook return false; 956800179c9SKees Cook 957800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 958800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 959800179c9SKees Cook return false; 960800179c9SKees Cook 961800179c9SKees Cook return true; 962800179c9SKees Cook } 963800179c9SKees Cook 964800179c9SKees Cook /** 965800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 966800179c9SKees Cook * @link: the source to hardlink from 967800179c9SKees Cook * 968800179c9SKees Cook * Block hardlink when all of: 969800179c9SKees Cook * - sysctl_protected_hardlinks enabled 970800179c9SKees Cook * - fsuid does not match inode 971800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 972f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 973800179c9SKees Cook * 974800179c9SKees Cook * Returns 0 if successful, -ve on error. 975800179c9SKees Cook */ 976800179c9SKees Cook static int may_linkat(struct path *link) 977800179c9SKees Cook { 978800179c9SKees Cook struct inode *inode; 979800179c9SKees Cook 980800179c9SKees Cook if (!sysctl_protected_hardlinks) 981800179c9SKees Cook return 0; 982800179c9SKees Cook 983800179c9SKees Cook inode = link->dentry->d_inode; 984800179c9SKees Cook 985800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 986800179c9SKees Cook * otherwise, it must be a safe source. 987800179c9SKees Cook */ 988f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 989800179c9SKees Cook return 0; 990800179c9SKees Cook 991a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 992800179c9SKees Cook return -EPERM; 993800179c9SKees Cook } 994800179c9SKees Cook 9953b2e7f75SAl Viro static __always_inline 9963b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9971da177e4SLinus Torvalds { 998ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9991cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1000fceef393SAl Viro struct inode *inode = nd->link_inode; 10016d7b5aaeSAl Viro int error; 10020a959df5SAl Viro const char *res; 10031da177e4SLinus Torvalds 10048fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10058fa9dd24SNeilBrown touch_atime(&last->link); 10068fa9dd24SNeilBrown cond_resched(); 10078fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10088fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10098fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10108fa9dd24SNeilBrown touch_atime(&last->link); 10118fa9dd24SNeilBrown } 10128fa9dd24SNeilBrown 1013bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1014bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1015bda0be7aSNeilBrown if (unlikely(error)) 10166920a440SAl Viro return ERR_PTR(error); 101736f3b4f6SAl Viro 101886acdca1SAl Viro nd->last_type = LAST_BIND; 1019d4dee48bSAl Viro res = inode->i_link; 1020d4dee48bSAl Viro if (!res) { 1021fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1022fceef393SAl Viro struct delayed_call *); 1023fceef393SAl Viro get = inode->i_op->get_link; 10248c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1025fceef393SAl Viro res = get(NULL, inode, &last->done); 10266b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10278c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10288c1b4566SAl Viro return ERR_PTR(-ECHILD); 1029fceef393SAl Viro res = get(dentry, inode, &last->done); 10308c1b4566SAl Viro } 10316b255391SAl Viro } else { 1032fceef393SAl Viro res = get(dentry, inode, &last->done); 10336b255391SAl Viro } 1034fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1035fab51e8aSAl Viro return res; 10360a959df5SAl Viro } 1037fab51e8aSAl Viro if (*res == '/') { 1038fab51e8aSAl Viro if (!nd->root.mnt) 1039fab51e8aSAl Viro set_root(nd); 1040248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1041fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1042fab51e8aSAl Viro while (unlikely(*++res == '/')) 1043fab51e8aSAl Viro ; 1044fab51e8aSAl Viro } 1045fab51e8aSAl Viro if (!*res) 1046fab51e8aSAl Viro res = NULL; 10470a959df5SAl Viro return res; 10480a959df5SAl Viro } 10496d7b5aaeSAl Viro 1050f015f126SDavid Howells /* 1051f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1052f015f126SDavid Howells * 1053f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1054f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1055f015f126SDavid Howells * Up is towards /. 1056f015f126SDavid Howells * 1057f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1058f015f126SDavid Howells * root. 1059f015f126SDavid Howells */ 1060bab77ebfSAl Viro int follow_up(struct path *path) 10611da177e4SLinus Torvalds { 10620714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10630714a533SAl Viro struct mount *parent; 10641da177e4SLinus Torvalds struct dentry *mountpoint; 106599b7db7bSNick Piggin 106648a066e7SAl Viro read_seqlock_excl(&mount_lock); 10670714a533SAl Viro parent = mnt->mnt_parent; 10683c0a6163SAl Viro if (parent == mnt) { 106948a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10701da177e4SLinus Torvalds return 0; 10711da177e4SLinus Torvalds } 10720714a533SAl Viro mntget(&parent->mnt); 1073a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107448a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1075bab77ebfSAl Viro dput(path->dentry); 1076bab77ebfSAl Viro path->dentry = mountpoint; 1077bab77ebfSAl Viro mntput(path->mnt); 10780714a533SAl Viro path->mnt = &parent->mnt; 10791da177e4SLinus Torvalds return 1; 10801da177e4SLinus Torvalds } 10814d359507SAl Viro EXPORT_SYMBOL(follow_up); 10821da177e4SLinus Torvalds 1083b5c84bf6SNick Piggin /* 10849875cf80SDavid Howells * Perform an automount 10859875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10869875cf80SDavid Howells * were called with. 10871da177e4SLinus Torvalds */ 1088756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10899875cf80SDavid Howells bool *need_mntput) 109031e6b01fSNick Piggin { 10919875cf80SDavid Howells struct vfsmount *mnt; 1092ea5b778aSDavid Howells int err; 10939875cf80SDavid Howells 10949875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10959875cf80SDavid Howells return -EREMOTE; 10969875cf80SDavid Howells 10970ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10980ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10990ec26fd0SMiklos Szeredi * the name. 11000ec26fd0SMiklos Szeredi * 11010ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11025a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11030ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11040ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11050ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11060ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11075a30d8a2SDavid Howells */ 1108756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1109d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11105a30d8a2SDavid Howells path->dentry->d_inode) 11119875cf80SDavid Howells return -EISDIR; 11120ec26fd0SMiklos Szeredi 1113756daf26SNeilBrown nd->total_link_count++; 1114756daf26SNeilBrown if (nd->total_link_count >= 40) 11159875cf80SDavid Howells return -ELOOP; 11169875cf80SDavid Howells 11179875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11189875cf80SDavid Howells if (IS_ERR(mnt)) { 11199875cf80SDavid Howells /* 11209875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11219875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11229875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11239875cf80SDavid Howells * 11249875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11259875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11269875cf80SDavid Howells * the path is inaccessible and we should say so. 11279875cf80SDavid Howells */ 1128756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11299875cf80SDavid Howells return -EREMOTE; 11309875cf80SDavid Howells return PTR_ERR(mnt); 113131e6b01fSNick Piggin } 1132ea5b778aSDavid Howells 11339875cf80SDavid Howells if (!mnt) /* mount collision */ 11349875cf80SDavid Howells return 0; 11359875cf80SDavid Howells 11368aef1884SAl Viro if (!*need_mntput) { 11378aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11388aef1884SAl Viro mntget(path->mnt); 11398aef1884SAl Viro *need_mntput = true; 11408aef1884SAl Viro } 114119a167afSAl Viro err = finish_automount(mnt, path); 1142ea5b778aSDavid Howells 1143ea5b778aSDavid Howells switch (err) { 1144ea5b778aSDavid Howells case -EBUSY: 1145ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114619a167afSAl Viro return 0; 1147ea5b778aSDavid Howells case 0: 11488aef1884SAl Viro path_put(path); 11499875cf80SDavid Howells path->mnt = mnt; 11509875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11519875cf80SDavid Howells return 0; 115219a167afSAl Viro default: 115319a167afSAl Viro return err; 11549875cf80SDavid Howells } 115519a167afSAl Viro 1156ea5b778aSDavid Howells } 11579875cf80SDavid Howells 11589875cf80SDavid Howells /* 11599875cf80SDavid Howells * Handle a dentry that is managed in some way. 1160cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11619875cf80SDavid Howells * - Flagged as mountpoint 11629875cf80SDavid Howells * - Flagged as automount point 11639875cf80SDavid Howells * 11649875cf80SDavid Howells * This may only be called in refwalk mode. 11659875cf80SDavid Howells * 11669875cf80SDavid Howells * Serialization is taken care of in namespace.c 11679875cf80SDavid Howells */ 1168756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11699875cf80SDavid Howells { 11708aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11719875cf80SDavid Howells unsigned managed; 11729875cf80SDavid Howells bool need_mntput = false; 11738aef1884SAl Viro int ret = 0; 11749875cf80SDavid Howells 11759875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11769875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11779875cf80SDavid Howells * the components of that value change under us */ 11789875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11799875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11809875cf80SDavid Howells unlikely(managed != 0)) { 1181cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1182cc53ce53SDavid Howells * being held. */ 1183cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1184cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1185cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11861aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1187cc53ce53SDavid Howells if (ret < 0) 11888aef1884SAl Viro break; 1189cc53ce53SDavid Howells } 1190cc53ce53SDavid Howells 11919875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11929875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11939875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11949875cf80SDavid Howells if (mounted) { 11959875cf80SDavid Howells dput(path->dentry); 11969875cf80SDavid Howells if (need_mntput) 1197463ffb2eSAl Viro mntput(path->mnt); 1198463ffb2eSAl Viro path->mnt = mounted; 1199463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12009875cf80SDavid Howells need_mntput = true; 12019875cf80SDavid Howells continue; 1202463ffb2eSAl Viro } 1203463ffb2eSAl Viro 12049875cf80SDavid Howells /* Something is mounted on this dentry in another 12059875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120648a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120748a066e7SAl Viro * get it */ 12081da177e4SLinus Torvalds } 12099875cf80SDavid Howells 12109875cf80SDavid Howells /* Handle an automount point */ 12119875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1212756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12139875cf80SDavid Howells if (ret < 0) 12148aef1884SAl Viro break; 12159875cf80SDavid Howells continue; 12169875cf80SDavid Howells } 12179875cf80SDavid Howells 12189875cf80SDavid Howells /* We didn't change the current path point */ 12199875cf80SDavid Howells break; 12209875cf80SDavid Howells } 12218aef1884SAl Viro 12228aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12238aef1884SAl Viro mntput(path->mnt); 1224e9742b53SAl Viro if (ret == -EISDIR || !ret) 1225e9742b53SAl Viro ret = 1; 12268402752eSAl Viro if (need_mntput) 12278402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12288402752eSAl Viro if (unlikely(ret < 0)) 12298402752eSAl Viro path_put_conditional(path, nd); 12308402752eSAl Viro return ret; 12311da177e4SLinus Torvalds } 12321da177e4SLinus Torvalds 1233cc53ce53SDavid Howells int follow_down_one(struct path *path) 12341da177e4SLinus Torvalds { 12351da177e4SLinus Torvalds struct vfsmount *mounted; 12361da177e4SLinus Torvalds 12371c755af4SAl Viro mounted = lookup_mnt(path); 12381da177e4SLinus Torvalds if (mounted) { 12399393bd07SAl Viro dput(path->dentry); 12409393bd07SAl Viro mntput(path->mnt); 12419393bd07SAl Viro path->mnt = mounted; 12429393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12431da177e4SLinus Torvalds return 1; 12441da177e4SLinus Torvalds } 12451da177e4SLinus Torvalds return 0; 12461da177e4SLinus Torvalds } 12474d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12481da177e4SLinus Torvalds 1249b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 125062a7375eSIan Kent { 1251b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1252b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 125362a7375eSIan Kent } 125462a7375eSIan Kent 12559875cf80SDavid Howells /* 1256287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1257287548e4SAl Viro * we meet a managed dentry that would need blocking. 12589875cf80SDavid Howells */ 12599875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1260254cf582SAl Viro struct inode **inode, unsigned *seqp) 12619875cf80SDavid Howells { 126262a7375eSIan Kent for (;;) { 1263c7105365SAl Viro struct mount *mounted; 126462a7375eSIan Kent /* 126562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126662a7375eSIan Kent * that wants to block transit. 126762a7375eSIan Kent */ 1268b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1269b8faf035SNeilBrown case -ECHILD: 1270b8faf035SNeilBrown default: 1271ab90911fSDavid Howells return false; 1272b8faf035SNeilBrown case -EISDIR: 1273b8faf035SNeilBrown return true; 1274b8faf035SNeilBrown case 0: 1275b8faf035SNeilBrown break; 1276b8faf035SNeilBrown } 127762a7375eSIan Kent 127862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1279b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 128062a7375eSIan Kent 1281474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12829875cf80SDavid Howells if (!mounted) 12839875cf80SDavid Howells break; 1284c7105365SAl Viro path->mnt = &mounted->mnt; 1285c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1286a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1287254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128859430262SLinus Torvalds /* 128959430262SLinus Torvalds * Update the inode too. We don't need to re-check the 129059430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129159430262SLinus Torvalds * because a mount-point is always pinned. 129259430262SLinus Torvalds */ 129359430262SLinus Torvalds *inode = path->dentry->d_inode; 12949875cf80SDavid Howells } 1295f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1296b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1297287548e4SAl Viro } 1298287548e4SAl Viro 129931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 130031e6b01fSNick Piggin { 13014023bfc9SAl Viro struct inode *inode = nd->inode; 130231e6b01fSNick Piggin 130331e6b01fSNick Piggin while (1) { 1304aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130531e6b01fSNick Piggin break; 130631e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130731e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130831e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130931e6b01fSNick Piggin unsigned seq; 131031e6b01fSNick Piggin 13114023bfc9SAl Viro inode = parent->d_inode; 131231e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1313aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1314aed434adSAl Viro return -ECHILD; 131531e6b01fSNick Piggin nd->path.dentry = parent; 131631e6b01fSNick Piggin nd->seq = seq; 1317397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1318397d425dSEric W. Biederman return -ENOENT; 131931e6b01fSNick Piggin break; 1320aed434adSAl Viro } else { 1321aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1322aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1323aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1324aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1325aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1326aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1327aed434adSAl Viro return -ECHILD; 1328aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132931e6b01fSNick Piggin break; 1330aed434adSAl Viro /* we know that mountpoint was pinned */ 1331aed434adSAl Viro nd->path.dentry = mountpoint; 1332aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1333aed434adSAl Viro inode = inode2; 1334aed434adSAl Viro nd->seq = seq; 133531e6b01fSNick Piggin } 1336aed434adSAl Viro } 1337aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1338b37199e6SAl Viro struct mount *mounted; 1339b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1340aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1341aed434adSAl Viro return -ECHILD; 1342b37199e6SAl Viro if (!mounted) 1343b37199e6SAl Viro break; 1344b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1345b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13464023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1347b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1348b37199e6SAl Viro } 13494023bfc9SAl Viro nd->inode = inode; 135031e6b01fSNick Piggin return 0; 135131e6b01fSNick Piggin } 135231e6b01fSNick Piggin 13539875cf80SDavid Howells /* 1354cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1355cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1356cc53ce53SDavid Howells * caller is permitted to proceed or not. 1357cc53ce53SDavid Howells */ 13587cc90cc3SAl Viro int follow_down(struct path *path) 1359cc53ce53SDavid Howells { 1360cc53ce53SDavid Howells unsigned managed; 1361cc53ce53SDavid Howells int ret; 1362cc53ce53SDavid Howells 1363cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1364cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1365cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1366cc53ce53SDavid Howells * being held. 1367cc53ce53SDavid Howells * 1368cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1369cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1370cc53ce53SDavid Howells * other than its daemon the right to mount on its 1371cc53ce53SDavid Howells * superstructure. 1372cc53ce53SDavid Howells * 1373cc53ce53SDavid Howells * The filesystem may sleep at this point. 1374cc53ce53SDavid Howells */ 1375cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1376cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1377cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1378ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13791aed3e42SAl Viro path->dentry, false); 1380cc53ce53SDavid Howells if (ret < 0) 1381cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1382cc53ce53SDavid Howells } 1383cc53ce53SDavid Howells 1384cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1385cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1386cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1387cc53ce53SDavid Howells if (!mounted) 1388cc53ce53SDavid Howells break; 1389cc53ce53SDavid Howells dput(path->dentry); 1390cc53ce53SDavid Howells mntput(path->mnt); 1391cc53ce53SDavid Howells path->mnt = mounted; 1392cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1393cc53ce53SDavid Howells continue; 1394cc53ce53SDavid Howells } 1395cc53ce53SDavid Howells 1396cc53ce53SDavid Howells /* Don't handle automount points here */ 1397cc53ce53SDavid Howells break; 1398cc53ce53SDavid Howells } 1399cc53ce53SDavid Howells return 0; 1400cc53ce53SDavid Howells } 14014d359507SAl Viro EXPORT_SYMBOL(follow_down); 1402cc53ce53SDavid Howells 1403cc53ce53SDavid Howells /* 14049875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14059875cf80SDavid Howells */ 14069875cf80SDavid Howells static void follow_mount(struct path *path) 14079875cf80SDavid Howells { 14089875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14099875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14109875cf80SDavid Howells if (!mounted) 14119875cf80SDavid Howells break; 14129875cf80SDavid Howells dput(path->dentry); 14139875cf80SDavid Howells mntput(path->mnt); 14149875cf80SDavid Howells path->mnt = mounted; 14159875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14169875cf80SDavid Howells } 14179875cf80SDavid Howells } 14189875cf80SDavid Howells 1419397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14201da177e4SLinus Torvalds { 14211da177e4SLinus Torvalds while(1) { 14224ac91378SJan Blunck struct dentry *old = nd->path.dentry; 14231da177e4SLinus Torvalds 14242a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14252a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14261da177e4SLinus Torvalds break; 14271da177e4SLinus Torvalds } 14284ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 14293088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 14303088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 14311da177e4SLinus Torvalds dput(old); 1432397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1433397d425dSEric W. Biederman return -ENOENT; 14341da177e4SLinus Torvalds break; 14351da177e4SLinus Torvalds } 14363088dd70SAl Viro if (!follow_up(&nd->path)) 14371da177e4SLinus Torvalds break; 14381da177e4SLinus Torvalds } 143979ed0226SAl Viro follow_mount(&nd->path); 144031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1441397d425dSEric W. Biederman return 0; 14421da177e4SLinus Torvalds } 14431da177e4SLinus Torvalds 14441da177e4SLinus Torvalds /* 1445bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1446bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1447bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1448baa03890SNick Piggin */ 1449e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1450e3c13928SAl Viro struct dentry *dir, 14516c51e513SAl Viro unsigned int flags) 1452baa03890SNick Piggin { 1453baa03890SNick Piggin struct dentry *dentry; 1454bad61189SMiklos Szeredi int error; 1455baa03890SNick Piggin 1456bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1457bad61189SMiklos Szeredi if (dentry) { 145839e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1459201f956eSAl Viro error = d_revalidate(dentry, flags); 1460bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146174ff0ffcSAl Viro if (!error) 14625542aa2fSEric W. Biederman d_invalidate(dentry); 1463bad61189SMiklos Szeredi dput(dentry); 146474ff0ffcSAl Viro return ERR_PTR(error); 1465bad61189SMiklos Szeredi } 1466bad61189SMiklos Szeredi } 1467bad61189SMiklos Szeredi } 1468baa03890SNick Piggin return dentry; 1469baa03890SNick Piggin } 1470baa03890SNick Piggin 1471baa03890SNick Piggin /* 147213a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 147313a2c3beSJ. Bruce Fields * unhashed. 1474bad61189SMiklos Szeredi * 1475bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 147644396f4bSJosef Bacik */ 1477bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 147872bd866aSAl Viro unsigned int flags) 147944396f4bSJosef Bacik { 148044396f4bSJosef Bacik struct dentry *old; 148144396f4bSJosef Bacik 148244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1483bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1484e188dc02SMiklos Szeredi dput(dentry); 148544396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1486e188dc02SMiklos Szeredi } 148744396f4bSJosef Bacik 148872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 148944396f4bSJosef Bacik if (unlikely(old)) { 149044396f4bSJosef Bacik dput(dentry); 149144396f4bSJosef Bacik dentry = old; 149244396f4bSJosef Bacik } 149344396f4bSJosef Bacik return dentry; 149444396f4bSJosef Bacik } 149544396f4bSJosef Bacik 1496e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 149772bd866aSAl Viro struct dentry *base, unsigned int flags) 1498a3255546SAl Viro { 14996c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1500a3255546SAl Viro 15016c51e513SAl Viro if (dentry) 1502a3255546SAl Viro return dentry; 1503bad61189SMiklos Szeredi 15046c51e513SAl Viro dentry = d_alloc(base, name); 15056c51e513SAl Viro if (unlikely(!dentry)) 15066c51e513SAl Viro return ERR_PTR(-ENOMEM); 15076c51e513SAl Viro 150872bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1509a3255546SAl Viro } 1510a3255546SAl Viro 1511e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1512254cf582SAl Viro struct path *path, struct inode **inode, 1513254cf582SAl Viro unsigned *seqp) 15141da177e4SLinus Torvalds { 15154ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151631e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15175a18fff2SAl Viro int status = 1; 15189875cf80SDavid Howells int err; 15199875cf80SDavid Howells 15203cac260aSAl Viro /* 1521b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15225d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15235d0f49c1SAl Viro * going to fall back to non-racy lookup. 1524b04f784eSNick Piggin */ 152531e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152631e6b01fSNick Piggin unsigned seq; 1527766c4cbfSAl Viro bool negative; 1528da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15295d0f49c1SAl Viro if (unlikely(!dentry)) { 15305d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15315d0f49c1SAl Viro return -ECHILD; 1532e9742b53SAl Viro return 0; 15335d0f49c1SAl Viro } 15345a18fff2SAl Viro 153512f8ad4bSLinus Torvalds /* 153612f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153712f8ad4bSLinus Torvalds * the dentry name information from lookup. 153812f8ad4bSLinus Torvalds */ 153963afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1540766c4cbfSAl Viro negative = d_is_negative(dentry); 15415d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 154212f8ad4bSLinus Torvalds return -ECHILD; 154312f8ad4bSLinus Torvalds 154412f8ad4bSLinus Torvalds /* 154512f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154612f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154712f8ad4bSLinus Torvalds * 154812f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 154912f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 155012f8ad4bSLinus Torvalds */ 15515d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 155231e6b01fSNick Piggin return -ECHILD; 15535a18fff2SAl Viro 1554254cf582SAl Viro *seqp = seq; 15555d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15564ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15575a18fff2SAl Viro if (unlikely(status <= 0)) { 15585d0f49c1SAl Viro if (unlazy_walk(nd, dentry, seq)) 15595d0f49c1SAl Viro return -ECHILD; 15605d0f49c1SAl Viro if (status == -ECHILD) 15615d0f49c1SAl Viro status = d_revalidate(dentry, nd->flags); 15625d0f49c1SAl Viro } else { 1563daf3761cSTrond Myklebust /* 1564daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1565daf3761cSTrond Myklebust * case that drops it. 1566daf3761cSTrond Myklebust */ 15675d0f49c1SAl Viro if (unlikely(negative)) 1568daf3761cSTrond Myklebust return -ENOENT; 156931e6b01fSNick Piggin path->mnt = mnt; 157031e6b01fSNick Piggin path->dentry = dentry; 1571254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1572e9742b53SAl Viro return 1; 1573254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15745a18fff2SAl Viro return -ECHILD; 15755d0f49c1SAl Viro } 15765a18fff2SAl Viro } else { 1577e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157881e6f520SAl Viro if (unlikely(!dentry)) 1579e9742b53SAl Viro return 0; 15805d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15814ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15825d0f49c1SAl Viro } 15835a18fff2SAl Viro if (unlikely(status <= 0)) { 1584e9742b53SAl Viro if (!status) 15855d0f49c1SAl Viro d_invalidate(dentry); 15865a18fff2SAl Viro dput(dentry); 15875a18fff2SAl Viro return status; 15885a18fff2SAl Viro } 1589766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1590766c4cbfSAl Viro dput(dentry); 1591766c4cbfSAl Viro return -ENOENT; 1592766c4cbfSAl Viro } 15935d0f49c1SAl Viro 15941da177e4SLinus Torvalds path->mnt = mnt; 15951da177e4SLinus Torvalds path->dentry = dentry; 1596756daf26SNeilBrown err = follow_managed(path, nd); 1597e9742b53SAl Viro if (likely(err > 0)) 159863afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15998402752eSAl Viro return err; 1600697f514dSMiklos Szeredi } 1601697f514dSMiklos Szeredi 1602697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1603e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1604e3c13928SAl Viro struct dentry *dir, 1605e3c13928SAl Viro unsigned int flags) 1606697f514dSMiklos Szeredi { 1607e3c13928SAl Viro struct dentry *dentry; 1608e3c13928SAl Viro inode_lock(dir->d_inode); 1609949a852eSAl Viro dentry = d_lookup(dir, name); 1610949a852eSAl Viro if (unlikely(dentry)) { 1611949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1612949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1613949a852eSAl Viro int error = d_revalidate(dentry, flags); 1614949a852eSAl Viro if (unlikely(error <= 0)) { 1615949a852eSAl Viro if (!error) 1616949a852eSAl Viro d_invalidate(dentry); 1617949a852eSAl Viro dput(dentry); 1618949a852eSAl Viro dentry = ERR_PTR(error); 1619949a852eSAl Viro } 1620949a852eSAl Viro } 1621949a852eSAl Viro if (dentry) { 1622949a852eSAl Viro inode_unlock(dir->d_inode); 1623949a852eSAl Viro return dentry; 1624949a852eSAl Viro } 1625949a852eSAl Viro } 1626949a852eSAl Viro dentry = d_alloc(dir, name); 1627949a852eSAl Viro if (unlikely(!dentry)) { 1628949a852eSAl Viro inode_unlock(dir->d_inode); 1629949a852eSAl Viro return ERR_PTR(-ENOMEM); 1630949a852eSAl Viro } 1631949a852eSAl Viro dentry = lookup_real(dir->d_inode, dentry, flags); 1632e3c13928SAl Viro inode_unlock(dir->d_inode); 1633e3c13928SAl Viro return dentry; 16341da177e4SLinus Torvalds } 16351da177e4SLinus Torvalds 163652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 163752094c8aSAl Viro { 163852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16394ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164052094c8aSAl Viro if (err != -ECHILD) 164152094c8aSAl Viro return err; 16426e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 164352094c8aSAl Viro return -ECHILD; 164452094c8aSAl Viro } 16454ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 164652094c8aSAl Viro } 164752094c8aSAl Viro 16489856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16499856fa1bSAl Viro { 16509856fa1bSAl Viro if (type == LAST_DOTDOT) { 16519e6697e2SAl Viro if (!nd->root.mnt) 16529e6697e2SAl Viro set_root(nd); 16539856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 165470291aecSAl Viro return follow_dotdot_rcu(nd); 16559856fa1bSAl Viro } else 1656397d425dSEric W. Biederman return follow_dotdot(nd); 16579856fa1bSAl Viro } 16589856fa1bSAl Viro return 0; 16599856fa1bSAl Viro } 16609856fa1bSAl Viro 1661181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1662181548c0SAl Viro struct inode *inode, unsigned seq) 1663d63ff28fSAl Viro { 1664626de996SAl Viro int error; 16651cf2665bSAl Viro struct saved *last; 1666756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1667626de996SAl Viro path_to_nameidata(link, nd); 1668626de996SAl Viro return -ELOOP; 1669626de996SAl Viro } 1670bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1671cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1672cd179f44SAl Viro mntget(link->mnt); 16737973387aSAl Viro } 1674626de996SAl Viro error = nd_alloc_stack(nd); 1675626de996SAl Viro if (unlikely(error)) { 1676bc40aee0SAl Viro if (error == -ECHILD) { 1677bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1678bc40aee0SAl Viro return -ECHILD; 1679bc40aee0SAl Viro error = nd_alloc_stack(nd); 1680bc40aee0SAl Viro } 1681bc40aee0SAl Viro if (error) { 1682cd179f44SAl Viro path_put(link); 1683626de996SAl Viro return error; 1684626de996SAl Viro } 1685bc40aee0SAl Viro } 1686626de996SAl Viro 1687ab104923SAl Viro last = nd->stack + nd->depth++; 16881cf2665bSAl Viro last->link = *link; 1689fceef393SAl Viro clear_delayed_call(&last->done); 1690fceef393SAl Viro nd->link_inode = inode; 16910450b2d1SAl Viro last->seq = seq; 1692d63ff28fSAl Viro return 1; 1693d63ff28fSAl Viro } 1694d63ff28fSAl Viro 16953ddcd056SLinus Torvalds /* 16963ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16973ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16983ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16993ddcd056SLinus Torvalds * for the common case. 17003ddcd056SLinus Torvalds */ 1701254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1702181548c0SAl Viro int follow, 1703181548c0SAl Viro struct inode *inode, unsigned seq) 17043ddcd056SLinus Torvalds { 1705d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1706d63ff28fSAl Viro return 0; 1707d63ff28fSAl Viro if (!follow) 1708d63ff28fSAl Viro return 0; 1709a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1710a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1711a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1712a7f77542SAl Viro return -ECHILD; 1713a7f77542SAl Viro } 1714181548c0SAl Viro return pick_link(nd, link, inode, seq); 17153ddcd056SLinus Torvalds } 17163ddcd056SLinus Torvalds 17174693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17184693a547SAl Viro 17194693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1720ce57dfc1SAl Viro { 1721caa85634SAl Viro struct path path; 1722ce57dfc1SAl Viro struct inode *inode; 1723254cf582SAl Viro unsigned seq; 1724ce57dfc1SAl Viro int err; 1725ce57dfc1SAl Viro /* 1726ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1727ce57dfc1SAl Viro * to be able to know about the current root directory and 1728ce57dfc1SAl Viro * parent relationships. 1729ce57dfc1SAl Viro */ 17304693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17314693a547SAl Viro err = handle_dots(nd, nd->last_type); 17324693a547SAl Viro if (flags & WALK_PUT) 17334693a547SAl Viro put_link(nd); 17344693a547SAl Viro return err; 17354693a547SAl Viro } 1736254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1737e9742b53SAl Viro if (unlikely(err <= 0)) { 1738697f514dSMiklos Szeredi if (err < 0) 1739f0a9ba70SAl Viro return err; 1740e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1741e3c13928SAl Viro nd->flags); 1742e3c13928SAl Viro if (IS_ERR(path.dentry)) 1743e3c13928SAl Viro return PTR_ERR(path.dentry); 17447500c38aSAl Viro 1745e3c13928SAl Viro path.mnt = nd->path.mnt; 1746e3c13928SAl Viro err = follow_managed(&path, nd); 1747e3c13928SAl Viro if (unlikely(err < 0)) 1748f0a9ba70SAl Viro return err; 1749697f514dSMiklos Szeredi 17507500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17517500c38aSAl Viro path_to_nameidata(&path, nd); 17527500c38aSAl Viro return -ENOENT; 17537500c38aSAl Viro } 17547500c38aSAl Viro 1755254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1756d4565649SAl Viro inode = d_backing_inode(path.dentry); 1757766c4cbfSAl Viro } 1758697f514dSMiklos Szeredi 17594693a547SAl Viro if (flags & WALK_PUT) 17604693a547SAl Viro put_link(nd); 1761181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1762d63ff28fSAl Viro if (unlikely(err)) 1763d63ff28fSAl Viro return err; 1764caa85634SAl Viro path_to_nameidata(&path, nd); 1765ce57dfc1SAl Viro nd->inode = inode; 1766254cf582SAl Viro nd->seq = seq; 1767ce57dfc1SAl Viro return 0; 1768ce57dfc1SAl Viro } 1769ce57dfc1SAl Viro 17701da177e4SLinus Torvalds /* 1771bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1772bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1773bfcfaa77SLinus Torvalds * 1774bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1775bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1776bfcfaa77SLinus Torvalds * fast. 1777bfcfaa77SLinus Torvalds * 1778bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1779bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1780bfcfaa77SLinus Torvalds * crossing operation. 1781bfcfaa77SLinus Torvalds * 1782bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1783bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1784bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1785bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1786bfcfaa77SLinus Torvalds */ 1787bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1788bfcfaa77SLinus Torvalds 1789f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1790bfcfaa77SLinus Torvalds 1791468a9428SGeorge Spelvin #ifdef HASH_MIX 1792468a9428SGeorge Spelvin 1793468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1794468a9428SGeorge Spelvin 1795468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 17962a18da7aSGeorge Spelvin /* 17972a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 17982a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 17992a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18002a18da7aSGeorge Spelvin * and no temporaries. 18012a18da7aSGeorge Spelvin * 18022a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18032a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18042a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18052a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18062a18da7aSGeorge Spelvin * 18072a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18082a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18092a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18102a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18112a18da7aSGeorge Spelvin * 18122a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18132a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18142a18da7aSGeorge Spelvin * toggling any given output bit. 18152a18da7aSGeorge Spelvin * 18162a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18172a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18182a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18192a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18202a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18212a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18222a18da7aSGeorge Spelvin * Perfect: 8192 258048 18232a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18242a18da7aSGeorge Spelvin */ 18252a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18262a18da7aSGeorge Spelvin ( x ^= (a), \ 18272a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18282a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18292a18da7aSGeorge Spelvin y *= 9 ) 1830bfcfaa77SLinus Torvalds 18310fed3ac8SGeorge Spelvin /* 18322a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18332a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18342a18da7aSGeorge Spelvin * work done before the hash value is used. 18350fed3ac8SGeorge Spelvin */ 18362a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18370fed3ac8SGeorge Spelvin { 18382a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18392a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18402a18da7aSGeorge Spelvin return y >> 32; 18410fed3ac8SGeorge Spelvin } 18420fed3ac8SGeorge Spelvin 1843bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1844bfcfaa77SLinus Torvalds 18452a18da7aSGeorge Spelvin /* 18462a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18472a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18482a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18492a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18502a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18512a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18522a18da7aSGeorge Spelvin * Perfect: 2048 31744 18532a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18542a18da7aSGeorge Spelvin */ 18552a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18562a18da7aSGeorge Spelvin ( x ^= (a), \ 18572a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18582a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18592a18da7aSGeorge Spelvin y *= 9 ) 1860bfcfaa77SLinus Torvalds 18612a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18620fed3ac8SGeorge Spelvin { 18632a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18642a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18650fed3ac8SGeorge Spelvin } 18660fed3ac8SGeorge Spelvin 1867bfcfaa77SLinus Torvalds #endif 1868bfcfaa77SLinus Torvalds 18692a18da7aSGeorge Spelvin /* 18702a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18712a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18722a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18732a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18742a18da7aSGeorge Spelvin * finds the delimiter after the name. 18752a18da7aSGeorge Spelvin */ 1876fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 1877bfcfaa77SLinus Torvalds { 18782a18da7aSGeorge Spelvin unsigned long a, x = 0, y = 0; 1879bfcfaa77SLinus Torvalds 1880bfcfaa77SLinus Torvalds for (;;) { 1881fcfd2fbfSGeorge Spelvin if (!len) 1882fcfd2fbfSGeorge Spelvin goto done; 1883e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1884bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1885bfcfaa77SLinus Torvalds break; 18862a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1887bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1888bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1889bfcfaa77SLinus Torvalds } 18902a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1891bfcfaa77SLinus Torvalds done: 18922a18da7aSGeorge Spelvin return fold_hash(x, y); 1893bfcfaa77SLinus Torvalds } 1894bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1895bfcfaa77SLinus Torvalds 1896fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1897fcfd2fbfSGeorge Spelvin u64 hashlen_string(const char *name) 1898fcfd2fbfSGeorge Spelvin { 18992a18da7aSGeorge Spelvin unsigned long a = 0, x = 0, y = 0, adata, mask, len; 1900fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1901fcfd2fbfSGeorge Spelvin 1902fcfd2fbfSGeorge Spelvin len = -sizeof(unsigned long); 1903fcfd2fbfSGeorge Spelvin do { 19042a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1905fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 1906fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1907fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1908fcfd2fbfSGeorge Spelvin 1909fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1910fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19112a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1912fcfd2fbfSGeorge Spelvin 19132a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1914fcfd2fbfSGeorge Spelvin } 1915fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1916fcfd2fbfSGeorge Spelvin 1917bfcfaa77SLinus Torvalds /* 1918bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1919d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1920bfcfaa77SLinus Torvalds */ 1921d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1922bfcfaa77SLinus Torvalds { 19232a18da7aSGeorge Spelvin unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len; 192436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1925bfcfaa77SLinus Torvalds 1926bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1927bfcfaa77SLinus Torvalds do { 19282a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1929bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1930e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 193136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 193236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1933bfcfaa77SLinus Torvalds 193436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 193536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 193636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19372a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 193836126f8fSLinus Torvalds 19392a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1940bfcfaa77SLinus Torvalds } 1941bfcfaa77SLinus Torvalds 19422a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1943bfcfaa77SLinus Torvalds 1944fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 1945fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 19460145acc2SLinus Torvalds { 19470145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 19480145acc2SLinus Torvalds while (len--) 1949fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19500145acc2SLinus Torvalds return end_name_hash(hash); 19510145acc2SLinus Torvalds } 1952ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19530145acc2SLinus Torvalds 1954fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1955fcfd2fbfSGeorge Spelvin u64 hash_string(const char *name) 1956fcfd2fbfSGeorge Spelvin { 1957fcfd2fbfSGeorge Spelvin unsigned long hash = init_name_hash(); 1958fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1959fcfd2fbfSGeorge Spelvin 1960fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1961fcfd2fbfSGeorge Spelvin do { 1962fcfd2fbfSGeorge Spelvin len++; 1963fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1964fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1965fcfd2fbfSGeorge Spelvin } while (c); 1966fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1967fcfd2fbfSGeorge Spelvin } 1968fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hash_string); 1969fcfd2fbfSGeorge Spelvin 19703ddcd056SLinus Torvalds /* 1971200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1972200e9ef7SLinus Torvalds * one character. 1973200e9ef7SLinus Torvalds */ 1974d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1975200e9ef7SLinus Torvalds { 1976200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1977200e9ef7SLinus Torvalds unsigned long len = 0, c; 1978200e9ef7SLinus Torvalds 1979200e9ef7SLinus Torvalds c = (unsigned char)*name; 1980200e9ef7SLinus Torvalds do { 1981200e9ef7SLinus Torvalds len++; 1982200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1983200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1984200e9ef7SLinus Torvalds } while (c && c != '/'); 1985d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1986200e9ef7SLinus Torvalds } 1987200e9ef7SLinus Torvalds 1988bfcfaa77SLinus Torvalds #endif 1989bfcfaa77SLinus Torvalds 1990200e9ef7SLinus Torvalds /* 19911da177e4SLinus Torvalds * Name resolution. 1992ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1993ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 19941da177e4SLinus Torvalds * 1995ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1996ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 19971da177e4SLinus Torvalds */ 19986de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 19991da177e4SLinus Torvalds { 20001da177e4SLinus Torvalds int err; 20011da177e4SLinus Torvalds 20021da177e4SLinus Torvalds while (*name=='/') 20031da177e4SLinus Torvalds name++; 20041da177e4SLinus Torvalds if (!*name) 20059e18f10aSAl Viro return 0; 20061da177e4SLinus Torvalds 20071da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20081da177e4SLinus Torvalds for(;;) { 2009d6bb3e90SLinus Torvalds u64 hash_len; 2010fe479a58SAl Viro int type; 20111da177e4SLinus Torvalds 201252094c8aSAl Viro err = may_lookup(nd); 20131da177e4SLinus Torvalds if (err) 20143595e234SAl Viro return err; 20151da177e4SLinus Torvalds 2016d6bb3e90SLinus Torvalds hash_len = hash_name(name); 20171da177e4SLinus Torvalds 2018fe479a58SAl Viro type = LAST_NORM; 2019d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2020fe479a58SAl Viro case 2: 2021200e9ef7SLinus Torvalds if (name[1] == '.') { 2022fe479a58SAl Viro type = LAST_DOTDOT; 202316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 202416c2cd71SAl Viro } 2025fe479a58SAl Viro break; 2026fe479a58SAl Viro case 1: 2027fe479a58SAl Viro type = LAST_DOT; 2028fe479a58SAl Viro } 20295a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20305a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 203116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20325a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2033a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2034da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20355a202bcdSAl Viro if (err < 0) 20363595e234SAl Viro return err; 2037d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2038d6bb3e90SLinus Torvalds name = this.name; 20395a202bcdSAl Viro } 20405a202bcdSAl Viro } 2041fe479a58SAl Viro 2042d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2043d6bb3e90SLinus Torvalds nd->last.name = name; 20445f4a6a69SAl Viro nd->last_type = type; 20455f4a6a69SAl Viro 2046d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2047d6bb3e90SLinus Torvalds if (!*name) 2048bdf6cbf1SAl Viro goto OK; 2049200e9ef7SLinus Torvalds /* 2050200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2051200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2052200e9ef7SLinus Torvalds */ 2053200e9ef7SLinus Torvalds do { 2054d6bb3e90SLinus Torvalds name++; 2055d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20568620c238SAl Viro if (unlikely(!*name)) { 20578620c238SAl Viro OK: 2058368ee9baSAl Viro /* pathname body, done */ 20598620c238SAl Viro if (!nd->depth) 20608620c238SAl Viro return 0; 20618620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2062368ee9baSAl Viro /* trailing symlink, done */ 20638620c238SAl Viro if (!name) 20648620c238SAl Viro return 0; 20658620c238SAl Viro /* last component of nested symlink */ 20664693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 20678620c238SAl Viro } else { 20684693a547SAl Viro err = walk_component(nd, WALK_GET); 20698620c238SAl Viro } 2070ce57dfc1SAl Viro if (err < 0) 20713595e234SAl Viro return err; 2072fe479a58SAl Viro 2073ce57dfc1SAl Viro if (err) { 2074626de996SAl Viro const char *s = get_link(nd); 20755a460275SAl Viro 2076a1c83681SViresh Kumar if (IS_ERR(s)) 20773595e234SAl Viro return PTR_ERR(s); 2078172a39a0SAl Viro err = 0; 207912b09578SAl Viro if (unlikely(!s)) { 208012b09578SAl Viro /* jumped */ 2081b9ff4429SAl Viro put_link(nd); 208212b09578SAl Viro } else { 2083071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 208432cd7468SAl Viro name = s; 20859e18f10aSAl Viro continue; 208648c8b0c5SAl Viro } 208731e6b01fSNick Piggin } 208897242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 208997242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 209097242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 209197242f99SAl Viro return -ECHILD; 209297242f99SAl Viro } 20933595e234SAl Viro return -ENOTDIR; 20945f4a6a69SAl Viro } 2095ce57dfc1SAl Viro } 209697242f99SAl Viro } 20971da177e4SLinus Torvalds 2098c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 209931e6b01fSNick Piggin { 210031e6b01fSNick Piggin int retval = 0; 2101c8a53ee5SAl Viro const char *s = nd->name->name; 210231e6b01fSNick Piggin 210331e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2104980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 210531e6b01fSNick Piggin nd->depth = 0; 21065b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2107b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2108b18825a7SDavid Howells struct inode *inode = root->d_inode; 2109fd2f7cb5SAl Viro if (*s) { 211044b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2111368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21125b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21135b6ca027SAl Viro if (retval) 2114368ee9baSAl Viro return ERR_PTR(retval); 211573d049a4SAl Viro } 21165b6ca027SAl Viro nd->path = nd->root; 21175b6ca027SAl Viro nd->inode = inode; 21185b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21198b61e74fSAl Viro rcu_read_lock(); 21205b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21218f47a016SAl Viro nd->root_seq = nd->seq; 212248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21235b6ca027SAl Viro } else { 21245b6ca027SAl Viro path_get(&nd->path); 21255b6ca027SAl Viro } 2126368ee9baSAl Viro return s; 21275b6ca027SAl Viro } 21285b6ca027SAl Viro 212931e6b01fSNick Piggin nd->root.mnt = NULL; 2130248fb5b9SAl Viro nd->path.mnt = NULL; 2131248fb5b9SAl Viro nd->path.dentry = NULL; 213231e6b01fSNick Piggin 213348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2134fd2f7cb5SAl Viro if (*s == '/') { 21359e6697e2SAl Viro if (flags & LOOKUP_RCU) 21368b61e74fSAl Viro rcu_read_lock(); 2137e41f7d4eSAl Viro set_root(nd); 2138248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2139ef55d917SAl Viro return s; 2140ef55d917SAl Viro nd->root.mnt = NULL; 2141ef55d917SAl Viro rcu_read_unlock(); 2142ef55d917SAl Viro return ERR_PTR(-ECHILD); 2143c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2144e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 214531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2146c28cc364SNick Piggin unsigned seq; 214731e6b01fSNick Piggin 21488b61e74fSAl Viro rcu_read_lock(); 214931e6b01fSNick Piggin 2150c28cc364SNick Piggin do { 2151c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 215231e6b01fSNick Piggin nd->path = fs->pwd; 2153ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2154c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2155c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2156e41f7d4eSAl Viro } else { 2157e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2158ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2159e41f7d4eSAl Viro } 2160ef55d917SAl Viro return s; 216131e6b01fSNick Piggin } else { 2162582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2163c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 216431e6b01fSNick Piggin struct dentry *dentry; 216531e6b01fSNick Piggin 21662903ff01SAl Viro if (!f.file) 2167368ee9baSAl Viro return ERR_PTR(-EBADF); 216831e6b01fSNick Piggin 21692903ff01SAl Viro dentry = f.file->f_path.dentry; 217031e6b01fSNick Piggin 2171fd2f7cb5SAl Viro if (*s) { 217244b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21732903ff01SAl Viro fdput(f); 2174368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2175f52e0c11SAl Viro } 21762903ff01SAl Viro } 21772903ff01SAl Viro 21782903ff01SAl Viro nd->path = f.file->f_path; 2179e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 21808b61e74fSAl Viro rcu_read_lock(); 218134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 218234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 21835590ff0dSUlrich Drepper } else { 21842903ff01SAl Viro path_get(&nd->path); 218534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 21861da177e4SLinus Torvalds } 218734a26b99SAl Viro fdput(f); 2188368ee9baSAl Viro return s; 2189e41f7d4eSAl Viro } 21909b4a9b14SAl Viro } 21919b4a9b14SAl Viro 21923bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 219395fa25d9SAl Viro { 219495fa25d9SAl Viro const char *s; 2195fec2fa24SAl Viro int error = may_follow_link(nd); 2196deb106c6SAl Viro if (unlikely(error)) 21973bdba28bSAl Viro return ERR_PTR(error); 219895fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2199fab51e8aSAl Viro nd->stack[0].name = NULL; 22003b2e7f75SAl Viro s = get_link(nd); 2201deb106c6SAl Viro return s ? s : ""; 220295fa25d9SAl Viro } 220395fa25d9SAl Viro 2204caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2205bd92d7feSAl Viro { 2206bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2207bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2208bd92d7feSAl Viro 2209bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2210deb106c6SAl Viro return walk_component(nd, 22114693a547SAl Viro nd->flags & LOOKUP_FOLLOW 22124693a547SAl Viro ? nd->depth 22134693a547SAl Viro ? WALK_PUT | WALK_GET 22144693a547SAl Viro : WALK_GET 22154693a547SAl Viro : 0); 2216bd92d7feSAl Viro } 2217bd92d7feSAl Viro 22189b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2219c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22209b4a9b14SAl Viro { 2221c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2222bd92d7feSAl Viro int err; 222331e6b01fSNick Piggin 2224368ee9baSAl Viro if (IS_ERR(s)) 2225368ee9baSAl Viro return PTR_ERR(s); 22263bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22273bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22283bdba28bSAl Viro s = trailing_symlink(nd); 22293bdba28bSAl Viro if (IS_ERR(s)) { 22303bdba28bSAl Viro err = PTR_ERR(s); 22316d7b5aaeSAl Viro break; 2232bd92d7feSAl Viro } 2233bd92d7feSAl Viro } 22349f1fafeeSAl Viro if (!err) 22359f1fafeeSAl Viro err = complete_walk(nd); 2236bd92d7feSAl Viro 2237deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2238deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2239bd23a539SAl Viro err = -ENOTDIR; 2240625b6d10SAl Viro if (!err) { 2241625b6d10SAl Viro *path = nd->path; 2242625b6d10SAl Viro nd->path.mnt = NULL; 2243625b6d10SAl Viro nd->path.dentry = NULL; 2244625b6d10SAl Viro } 2245deb106c6SAl Viro terminate_walk(nd); 2246bd92d7feSAl Viro return err; 224731e6b01fSNick Piggin } 224831e6b01fSNick Piggin 2249625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22509ad1aaa6SAl Viro struct path *path, struct path *root) 2251873f1eedSJeff Layton { 2252894bc8c4SAl Viro int retval; 22539883d185SAl Viro struct nameidata nd; 2254abc9f5beSAl Viro if (IS_ERR(name)) 2255abc9f5beSAl Viro return PTR_ERR(name); 22569ad1aaa6SAl Viro if (unlikely(root)) { 22579ad1aaa6SAl Viro nd.root = *root; 22589ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22599ad1aaa6SAl Viro } 22609883d185SAl Viro set_nameidata(&nd, dfd, name); 2261c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2262873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2263c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2264873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2265c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2266873f1eedSJeff Layton 2267873f1eedSJeff Layton if (likely(!retval)) 2268625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 22699883d185SAl Viro restore_nameidata(); 2270e4bd1c1aSAl Viro putname(name); 2271873f1eedSJeff Layton return retval; 2272873f1eedSJeff Layton } 2273873f1eedSJeff Layton 22748bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2275c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2276391172c4SAl Viro struct path *parent) 22778bcb77faSAl Viro { 2278c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2279368ee9baSAl Viro int err; 2280368ee9baSAl Viro if (IS_ERR(s)) 2281368ee9baSAl Viro return PTR_ERR(s); 2282368ee9baSAl Viro err = link_path_walk(s, nd); 22838bcb77faSAl Viro if (!err) 22848bcb77faSAl Viro err = complete_walk(nd); 2285391172c4SAl Viro if (!err) { 2286391172c4SAl Viro *parent = nd->path; 2287391172c4SAl Viro nd->path.mnt = NULL; 2288391172c4SAl Viro nd->path.dentry = NULL; 2289391172c4SAl Viro } 2290deb106c6SAl Viro terminate_walk(nd); 22918bcb77faSAl Viro return err; 22928bcb77faSAl Viro } 22938bcb77faSAl Viro 22945c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2295391172c4SAl Viro unsigned int flags, struct path *parent, 2296391172c4SAl Viro struct qstr *last, int *type) 22978bcb77faSAl Viro { 22988bcb77faSAl Viro int retval; 22999883d185SAl Viro struct nameidata nd; 23008bcb77faSAl Viro 23015c31b6ceSAl Viro if (IS_ERR(name)) 23025c31b6ceSAl Viro return name; 23039883d185SAl Viro set_nameidata(&nd, dfd, name); 2304c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23058bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2306c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23078bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2308c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2309391172c4SAl Viro if (likely(!retval)) { 2310391172c4SAl Viro *last = nd.last; 2311391172c4SAl Viro *type = nd.last_type; 2312391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23135c31b6ceSAl Viro } else { 23145c31b6ceSAl Viro putname(name); 23155c31b6ceSAl Viro name = ERR_PTR(retval); 2316391172c4SAl Viro } 23179883d185SAl Viro restore_nameidata(); 23185c31b6ceSAl Viro return name; 23198bcb77faSAl Viro } 23208bcb77faSAl Viro 232179714f72SAl Viro /* does lookup, returns the object with parent locked */ 232279714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23235590ff0dSUlrich Drepper { 23245c31b6ceSAl Viro struct filename *filename; 23255c31b6ceSAl Viro struct dentry *d; 2326391172c4SAl Viro struct qstr last; 2327391172c4SAl Viro int type; 232851689104SPaul Moore 23295c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23305c31b6ceSAl Viro &last, &type); 233151689104SPaul Moore if (IS_ERR(filename)) 233251689104SPaul Moore return ERR_CAST(filename); 23335c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2334391172c4SAl Viro path_put(path); 23355c31b6ceSAl Viro putname(filename); 23365c31b6ceSAl Viro return ERR_PTR(-EINVAL); 233779714f72SAl Viro } 23385955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2339391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 234079714f72SAl Viro if (IS_ERR(d)) { 23415955102cSAl Viro inode_unlock(path->dentry->d_inode); 2342391172c4SAl Viro path_put(path); 234379714f72SAl Viro } 234451689104SPaul Moore putname(filename); 234579714f72SAl Viro return d; 23465590ff0dSUlrich Drepper } 23475590ff0dSUlrich Drepper 2348d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2349d1811465SAl Viro { 2350abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2351abc9f5beSAl Viro flags, path, NULL); 2352d1811465SAl Viro } 23534d359507SAl Viro EXPORT_SYMBOL(kern_path); 2354d1811465SAl Viro 235516f18200SJosef 'Jeff' Sipek /** 235616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 235716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 235816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 235916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 236016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2361e0a01249SAl Viro * @path: pointer to struct path to fill 236216f18200SJosef 'Jeff' Sipek */ 236316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 236416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2365e0a01249SAl Viro struct path *path) 236616f18200SJosef 'Jeff' Sipek { 23679ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 23689ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2369abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2370abc9f5beSAl Viro flags , path, &root); 237116f18200SJosef 'Jeff' Sipek } 23724d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 237316f18200SJosef 'Jeff' Sipek 2374eead1911SChristoph Hellwig /** 23753c9fe8cdSMiklos Szeredi * lookup_hash - lookup single pathname component on already hashed name 23763c9fe8cdSMiklos Szeredi * @name: name and hash to lookup 23773c9fe8cdSMiklos Szeredi * @base: base directory to lookup from 23783c9fe8cdSMiklos Szeredi * 23793c9fe8cdSMiklos Szeredi * The name must have been verified and hashed (see lookup_one_len()). Using 23803c9fe8cdSMiklos Szeredi * this after just full_name_hash() is unsafe. 23813c9fe8cdSMiklos Szeredi * 23823c9fe8cdSMiklos Szeredi * This function also doesn't check for search permission on base directory. 23833c9fe8cdSMiklos Szeredi * 23843c9fe8cdSMiklos Szeredi * Use lookup_one_len_unlocked() instead, unless you really know what you are 23853c9fe8cdSMiklos Szeredi * doing. 23863c9fe8cdSMiklos Szeredi * 23873c9fe8cdSMiklos Szeredi * Do not hold i_mutex; this helper takes i_mutex if necessary. 23883c9fe8cdSMiklos Szeredi */ 23893c9fe8cdSMiklos Szeredi struct dentry *lookup_hash(const struct qstr *name, struct dentry *base) 23903c9fe8cdSMiklos Szeredi { 23913c9fe8cdSMiklos Szeredi struct dentry *ret; 23923c9fe8cdSMiklos Szeredi 23933c9fe8cdSMiklos Szeredi ret = lookup_dcache(name, base, 0); 23943c9fe8cdSMiklos Szeredi if (!ret) 23953c9fe8cdSMiklos Szeredi ret = lookup_slow(name, base, 0); 23963c9fe8cdSMiklos Szeredi 23973c9fe8cdSMiklos Szeredi return ret; 23983c9fe8cdSMiklos Szeredi } 23993c9fe8cdSMiklos Szeredi EXPORT_SYMBOL(lookup_hash); 24003c9fe8cdSMiklos Szeredi 24013c9fe8cdSMiklos Szeredi /** 2402a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2403eead1911SChristoph Hellwig * @name: pathname component to lookup 2404eead1911SChristoph Hellwig * @base: base directory to lookup from 2405eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2406eead1911SChristoph Hellwig * 2407a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24089e7543e9SAl Viro * not be called by generic code. 2409bbddca8eSNeilBrown * 2410bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2411eead1911SChristoph Hellwig */ 2412057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2413057f6c01SJames Morris { 2414057f6c01SJames Morris struct qstr this; 24156a96ba54SAl Viro unsigned int c; 2416cda309deSMiklos Szeredi int err; 2417057f6c01SJames Morris 24185955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24192f9092e1SDavid Woodhouse 24206a96ba54SAl Viro this.name = name; 24216a96ba54SAl Viro this.len = len; 24220145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 24236a96ba54SAl Viro if (!len) 24246a96ba54SAl Viro return ERR_PTR(-EACCES); 24256a96ba54SAl Viro 242621d8a15aSAl Viro if (unlikely(name[0] == '.')) { 242721d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 242821d8a15aSAl Viro return ERR_PTR(-EACCES); 242921d8a15aSAl Viro } 243021d8a15aSAl Viro 24316a96ba54SAl Viro while (len--) { 24326a96ba54SAl Viro c = *(const unsigned char *)name++; 24336a96ba54SAl Viro if (c == '/' || c == '\0') 24346a96ba54SAl Viro return ERR_PTR(-EACCES); 24356a96ba54SAl Viro } 24365a202bcdSAl Viro /* 24375a202bcdSAl Viro * See if the low-level filesystem might want 24385a202bcdSAl Viro * to use its own hash.. 24395a202bcdSAl Viro */ 24405a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2441da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24425a202bcdSAl Viro if (err < 0) 24435a202bcdSAl Viro return ERR_PTR(err); 24445a202bcdSAl Viro } 2445eead1911SChristoph Hellwig 2446cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2447cda309deSMiklos Szeredi if (err) 2448cda309deSMiklos Szeredi return ERR_PTR(err); 2449cda309deSMiklos Szeredi 245072bd866aSAl Viro return __lookup_hash(&this, base, 0); 2451057f6c01SJames Morris } 24524d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2453057f6c01SJames Morris 2454bbddca8eSNeilBrown /** 2455bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2456bbddca8eSNeilBrown * @name: pathname component to lookup 2457bbddca8eSNeilBrown * @base: base directory to lookup from 2458bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2459bbddca8eSNeilBrown * 2460bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2461bbddca8eSNeilBrown * not be called by generic code. 2462bbddca8eSNeilBrown * 2463bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2464bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2465bbddca8eSNeilBrown */ 2466bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2467bbddca8eSNeilBrown struct dentry *base, int len) 2468bbddca8eSNeilBrown { 2469bbddca8eSNeilBrown struct qstr this; 2470bbddca8eSNeilBrown unsigned int c; 2471bbddca8eSNeilBrown int err; 2472bbddca8eSNeilBrown 2473bbddca8eSNeilBrown this.name = name; 2474bbddca8eSNeilBrown this.len = len; 2475bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2476bbddca8eSNeilBrown if (!len) 2477bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2478bbddca8eSNeilBrown 2479bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2480bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2481bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2482bbddca8eSNeilBrown } 2483bbddca8eSNeilBrown 2484bbddca8eSNeilBrown while (len--) { 2485bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2486bbddca8eSNeilBrown if (c == '/' || c == '\0') 2487bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2488bbddca8eSNeilBrown } 2489bbddca8eSNeilBrown /* 2490bbddca8eSNeilBrown * See if the low-level filesystem might want 2491bbddca8eSNeilBrown * to use its own hash.. 2492bbddca8eSNeilBrown */ 2493bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2494bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2495bbddca8eSNeilBrown if (err < 0) 2496bbddca8eSNeilBrown return ERR_PTR(err); 2497bbddca8eSNeilBrown } 2498bbddca8eSNeilBrown 2499bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2500bbddca8eSNeilBrown if (err) 2501bbddca8eSNeilBrown return ERR_PTR(err); 2502bbddca8eSNeilBrown 25033c9fe8cdSMiklos Szeredi return lookup_hash(&this, base); 2504bbddca8eSNeilBrown } 2505bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2506bbddca8eSNeilBrown 25071fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25081fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25091da177e4SLinus Torvalds { 2510abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2511abc9f5beSAl Viro flags, path, NULL); 25121da177e4SLinus Torvalds } 2513b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25141fa1e7f6SAndy Whitcroft 2515873f1eedSJeff Layton /* 2516873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2517873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2518873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2519873f1eedSJeff Layton * path-walking is complete. 2520873f1eedSJeff Layton */ 2521a2ec4a2dSAl Viro static inline struct filename * 2522f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2523f5beed75SAl Viro struct path *parent, 2524f5beed75SAl Viro struct qstr *last, 2525f5beed75SAl Viro int *type, 25269e790bd6SJeff Layton unsigned int flags) 25272ad94ae6SAl Viro { 25289e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 25295c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 25305c31b6ceSAl Viro parent, last, type); 25312ad94ae6SAl Viro } 25322ad94ae6SAl Viro 25338033426eSJeff Layton /** 2534197df04cSAl Viro * mountpoint_last - look up last component for umount 25358033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25368033426eSJeff Layton * @path: pointer to container for result 25378033426eSJeff Layton * 25388033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25398033426eSJeff Layton * need to resolve the path without doing any revalidation. 25408033426eSJeff Layton * 25418033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25428033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25438033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25448033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25458033426eSJeff Layton * bogus and it doesn't exist. 25468033426eSJeff Layton * 25478033426eSJeff Layton * Returns: 25488033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 25498033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 25508033426eSJeff Layton * put in this case. 25518033426eSJeff Layton * 25528033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 25538033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 25548033426eSJeff Layton * The nd->path reference will also be put. 25558033426eSJeff Layton * 25568033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 25578033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 25588033426eSJeff Layton * to the link, and nd->path will *not* be put. 25598033426eSJeff Layton */ 25608033426eSJeff Layton static int 2561197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 25628033426eSJeff Layton { 25638033426eSJeff Layton int error = 0; 25648033426eSJeff Layton struct dentry *dentry; 25658033426eSJeff Layton struct dentry *dir = nd->path.dentry; 25668033426eSJeff Layton 256735759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 256835759521SAl Viro if (nd->flags & LOOKUP_RCU) { 25696e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2570deb106c6SAl Viro return -ECHILD; 25718033426eSJeff Layton } 25728033426eSJeff Layton 25738033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 25748033426eSJeff Layton 25758033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 25768033426eSJeff Layton error = handle_dots(nd, nd->last_type); 257735759521SAl Viro if (error) 2578deb106c6SAl Viro return error; 25798033426eSJeff Layton dentry = dget(nd->path.dentry); 2580949a852eSAl Viro } else { 25818033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 25828033426eSJeff Layton if (!dentry) { 25838033426eSJeff Layton /* 2584949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2585949a852eSAl Viro * cache, so that means that this dentry is probably 2586949a852eSAl Viro * a symlink or the path doesn't actually point 2587949a852eSAl Viro * to a mounted dentry. 25888033426eSJeff Layton */ 2589949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2590949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2591949a852eSAl Viro if (IS_ERR(dentry)) 2592deb106c6SAl Viro return PTR_ERR(dentry); 25938033426eSJeff Layton } 2594bcceeebaSDave Jones } 2595698934dfSDavid Howells if (d_is_negative(dentry)) { 25968033426eSJeff Layton dput(dentry); 2597deb106c6SAl Viro return -ENOENT; 259835759521SAl Viro } 2599191d7f73SAl Viro if (nd->depth) 2600191d7f73SAl Viro put_link(nd); 26018033426eSJeff Layton path->dentry = dentry; 2602295dc39dSVasily Averin path->mnt = nd->path.mnt; 2603181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2604181548c0SAl Viro d_backing_inode(dentry), 0); 2605deb106c6SAl Viro if (unlikely(error)) 2606d63ff28fSAl Viro return error; 2607295dc39dSVasily Averin mntget(path->mnt); 26088033426eSJeff Layton follow_mount(path); 2609deb106c6SAl Viro return 0; 26108033426eSJeff Layton } 26118033426eSJeff Layton 26128033426eSJeff Layton /** 2613197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26142a78b857SMasanari Iida * @nd: lookup context 26158033426eSJeff Layton * @flags: lookup flags 2616c8a53ee5SAl Viro * @path: pointer to container for result 26178033426eSJeff Layton * 26188033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2619606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26208033426eSJeff Layton */ 26218033426eSJeff Layton static int 2622c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26238033426eSJeff Layton { 2624c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2625368ee9baSAl Viro int err; 2626368ee9baSAl Viro if (IS_ERR(s)) 2627368ee9baSAl Viro return PTR_ERR(s); 26283bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 26293bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 26303bdba28bSAl Viro s = trailing_symlink(nd); 26313bdba28bSAl Viro if (IS_ERR(s)) { 26323bdba28bSAl Viro err = PTR_ERR(s); 26338033426eSJeff Layton break; 26348033426eSJeff Layton } 26353bdba28bSAl Viro } 2636deb106c6SAl Viro terminate_walk(nd); 26378033426eSJeff Layton return err; 26388033426eSJeff Layton } 26398033426eSJeff Layton 26402d864651SAl Viro static int 2641668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26422d864651SAl Viro unsigned int flags) 26432d864651SAl Viro { 26449883d185SAl Viro struct nameidata nd; 2645cbaab2dbSAl Viro int error; 2646668696dcSAl Viro if (IS_ERR(name)) 2647668696dcSAl Viro return PTR_ERR(name); 26489883d185SAl Viro set_nameidata(&nd, dfd, name); 2649c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26502d864651SAl Viro if (unlikely(error == -ECHILD)) 2651c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26522d864651SAl Viro if (unlikely(error == -ESTALE)) 2653c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26542d864651SAl Viro if (likely(!error)) 2655668696dcSAl Viro audit_inode(name, path->dentry, 0); 26569883d185SAl Viro restore_nameidata(); 2657668696dcSAl Viro putname(name); 26582d864651SAl Viro return error; 26592d864651SAl Viro } 26602d864651SAl Viro 26618033426eSJeff Layton /** 2662197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26638033426eSJeff Layton * @dfd: directory file descriptor 26648033426eSJeff Layton * @name: pathname from userland 26658033426eSJeff Layton * @flags: lookup flags 26668033426eSJeff Layton * @path: pointer to container to hold result 26678033426eSJeff Layton * 26688033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26698033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26708033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26718033426eSJeff Layton * and avoid revalidating the last component. 26728033426eSJeff Layton * 26738033426eSJeff Layton * Returns 0 and populates "path" on success. 26748033426eSJeff Layton */ 26758033426eSJeff Layton int 2676197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26778033426eSJeff Layton struct path *path) 26788033426eSJeff Layton { 2679cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26808033426eSJeff Layton } 26818033426eSJeff Layton 26822d864651SAl Viro int 26832d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 26842d864651SAl Viro unsigned int flags) 26852d864651SAl Viro { 2686cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 26872d864651SAl Viro } 26882d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 26892d864651SAl Viro 2690cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26911da177e4SLinus Torvalds { 26928e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2693da9592edSDavid Howells 26948e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26951da177e4SLinus Torvalds return 0; 26968e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26971da177e4SLinus Torvalds return 0; 269823adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26991da177e4SLinus Torvalds } 2700cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27011da177e4SLinus Torvalds 27021da177e4SLinus Torvalds /* 27031da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27041da177e4SLinus Torvalds * whether the type of victim is right. 27051da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27061da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27071da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27081da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27091da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27101da177e4SLinus Torvalds * a. be owner of dir, or 27111da177e4SLinus Torvalds * b. be owner of victim, or 27121da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27131da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27141da177e4SLinus Torvalds * links pointing to it. 27151da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27161da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27171da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 27181da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 27191da177e4SLinus Torvalds * nfs_async_unlink(). 27201da177e4SLinus Torvalds */ 2721b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27221da177e4SLinus Torvalds { 272363afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27241da177e4SLinus Torvalds int error; 27251da177e4SLinus Torvalds 2726b18825a7SDavid Howells if (d_is_negative(victim)) 27271da177e4SLinus Torvalds return -ENOENT; 2728b18825a7SDavid Howells BUG_ON(!inode); 27291da177e4SLinus Torvalds 27301da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27314fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27321da177e4SLinus Torvalds 2733f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27341da177e4SLinus Torvalds if (error) 27351da177e4SLinus Torvalds return error; 27361da177e4SLinus Torvalds if (IS_APPEND(dir)) 27371da177e4SLinus Torvalds return -EPERM; 2738b18825a7SDavid Howells 2739b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2740b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 27411da177e4SLinus Torvalds return -EPERM; 27421da177e4SLinus Torvalds if (isdir) { 274344b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27441da177e4SLinus Torvalds return -ENOTDIR; 27451da177e4SLinus Torvalds if (IS_ROOT(victim)) 27461da177e4SLinus Torvalds return -EBUSY; 274744b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27481da177e4SLinus Torvalds return -EISDIR; 27491da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27501da177e4SLinus Torvalds return -ENOENT; 27511da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27521da177e4SLinus Torvalds return -EBUSY; 27531da177e4SLinus Torvalds return 0; 27541da177e4SLinus Torvalds } 27551da177e4SLinus Torvalds 27561da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27571da177e4SLinus Torvalds * dir. 27581da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27591da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27601da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 27611da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 27621da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 27631da177e4SLinus Torvalds */ 2764a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27651da177e4SLinus Torvalds { 276614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27671da177e4SLinus Torvalds if (child->d_inode) 27681da177e4SLinus Torvalds return -EEXIST; 27691da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27701da177e4SLinus Torvalds return -ENOENT; 2771f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27721da177e4SLinus Torvalds } 27731da177e4SLinus Torvalds 27741da177e4SLinus Torvalds /* 27751da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27761da177e4SLinus Torvalds */ 27771da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27781da177e4SLinus Torvalds { 27791da177e4SLinus Torvalds struct dentry *p; 27801da177e4SLinus Torvalds 27811da177e4SLinus Torvalds if (p1 == p2) { 27825955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27831da177e4SLinus Torvalds return NULL; 27841da177e4SLinus Torvalds } 27851da177e4SLinus Torvalds 2786a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 27871da177e4SLinus Torvalds 2788e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2789e2761a11SOGAWA Hirofumi if (p) { 27905955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27915955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27921da177e4SLinus Torvalds return p; 27931da177e4SLinus Torvalds } 27941da177e4SLinus Torvalds 2795e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2796e2761a11SOGAWA Hirofumi if (p) { 27975955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27985955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27991da177e4SLinus Torvalds return p; 28001da177e4SLinus Torvalds } 28011da177e4SLinus Torvalds 28025955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28035955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28041da177e4SLinus Torvalds return NULL; 28051da177e4SLinus Torvalds } 28064d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28071da177e4SLinus Torvalds 28081da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28091da177e4SLinus Torvalds { 28105955102cSAl Viro inode_unlock(p1->d_inode); 28111da177e4SLinus Torvalds if (p1 != p2) { 28125955102cSAl Viro inode_unlock(p2->d_inode); 2813a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 28141da177e4SLinus Torvalds } 28151da177e4SLinus Torvalds } 28164d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28171da177e4SLinus Torvalds 28184acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2819312b63fbSAl Viro bool want_excl) 28201da177e4SLinus Torvalds { 2821a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28221da177e4SLinus Torvalds if (error) 28231da177e4SLinus Torvalds return error; 28241da177e4SLinus Torvalds 2825acfa4380SAl Viro if (!dir->i_op->create) 28261da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28271da177e4SLinus Torvalds mode &= S_IALLUGO; 28281da177e4SLinus Torvalds mode |= S_IFREG; 28291da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28301da177e4SLinus Torvalds if (error) 28311da177e4SLinus Torvalds return error; 2832312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2833a74574aaSStephen Smalley if (!error) 2834f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28351da177e4SLinus Torvalds return error; 28361da177e4SLinus Torvalds } 28374d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28381da177e4SLinus Torvalds 283973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 28401da177e4SLinus Torvalds { 28413fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28421da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28431da177e4SLinus Torvalds int error; 28441da177e4SLinus Torvalds 28451da177e4SLinus Torvalds if (!inode) 28461da177e4SLinus Torvalds return -ENOENT; 28471da177e4SLinus Torvalds 2848c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2849c8fe8f30SChristoph Hellwig case S_IFLNK: 28501da177e4SLinus Torvalds return -ELOOP; 2851c8fe8f30SChristoph Hellwig case S_IFDIR: 2852c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28531da177e4SLinus Torvalds return -EISDIR; 2854c8fe8f30SChristoph Hellwig break; 2855c8fe8f30SChristoph Hellwig case S_IFBLK: 2856c8fe8f30SChristoph Hellwig case S_IFCHR: 28573fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 28581da177e4SLinus Torvalds return -EACCES; 2859c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2860c8fe8f30SChristoph Hellwig case S_IFIFO: 2861c8fe8f30SChristoph Hellwig case S_IFSOCK: 28621da177e4SLinus Torvalds flag &= ~O_TRUNC; 2863c8fe8f30SChristoph Hellwig break; 28644a3fd211SDave Hansen } 2865b41572e9SDave Hansen 286662fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2867b41572e9SDave Hansen if (error) 2868b41572e9SDave Hansen return error; 28696146f0d5SMimi Zohar 28701da177e4SLinus Torvalds /* 28711da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28721da177e4SLinus Torvalds */ 28731da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28748737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28757715b521SAl Viro return -EPERM; 28761da177e4SLinus Torvalds if (flag & O_TRUNC) 28777715b521SAl Viro return -EPERM; 28781da177e4SLinus Torvalds } 28791da177e4SLinus Torvalds 28801da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28812e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28827715b521SAl Viro return -EPERM; 28831da177e4SLinus Torvalds 2884f3c7691eSJ. Bruce Fields return 0; 28857715b521SAl Viro } 28867715b521SAl Viro 2887e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28887715b521SAl Viro { 2889e1181ee6SJeff Layton struct path *path = &filp->f_path; 28907715b521SAl Viro struct inode *inode = path->dentry->d_inode; 28917715b521SAl Viro int error = get_write_access(inode); 28921da177e4SLinus Torvalds if (error) 28937715b521SAl Viro return error; 28941da177e4SLinus Torvalds /* 28951da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 28961da177e4SLinus Torvalds */ 2897d7a06983SJeff Layton error = locks_verify_locked(filp); 2898be6d3e56SKentaro Takeda if (!error) 2899ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29001da177e4SLinus Torvalds if (!error) { 29017715b521SAl Viro error = do_truncate(path->dentry, 0, 2902d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2903e1181ee6SJeff Layton filp); 29041da177e4SLinus Torvalds } 29051da177e4SLinus Torvalds put_write_access(inode); 2906acd0c935SMimi Zohar return error; 29071da177e4SLinus Torvalds } 29081da177e4SLinus Torvalds 2909d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2910d57999e1SDave Hansen { 29118a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29128a5e929dSAl Viro flag--; 2913d57999e1SDave Hansen return flag; 2914d57999e1SDave Hansen } 2915d57999e1SDave Hansen 2916d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2917d18e9008SMiklos Szeredi { 2918d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2919d18e9008SMiklos Szeredi if (error) 2920d18e9008SMiklos Szeredi return error; 2921d18e9008SMiklos Szeredi 2922d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2923d18e9008SMiklos Szeredi if (error) 2924d18e9008SMiklos Szeredi return error; 2925d18e9008SMiklos Szeredi 2926d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2927d18e9008SMiklos Szeredi } 2928d18e9008SMiklos Szeredi 29291acf0af9SDavid Howells /* 29301acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29311acf0af9SDavid Howells * dentry. 29321acf0af9SDavid Howells * 29331acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29341acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29351acf0af9SDavid Howells * 29361acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29371acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29381acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29391acf0af9SDavid Howells * 29401acf0af9SDavid Howells * Returns an error code otherwise. 29411acf0af9SDavid Howells */ 29422675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 294330d90494SAl Viro struct path *path, struct file *file, 2944015c3bbcSMiklos Szeredi const struct open_flags *op, 294564894cf8SAl Viro bool got_write, bool need_lookup, 294647237687SAl Viro int *opened) 2947d18e9008SMiklos Szeredi { 2948d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2949d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2950d18e9008SMiklos Szeredi umode_t mode; 2951d18e9008SMiklos Szeredi int error; 2952d18e9008SMiklos Szeredi int acc_mode; 2953d18e9008SMiklos Szeredi int create_error = 0; 2954d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2955116cc022SMiklos Szeredi bool excl; 2956d18e9008SMiklos Szeredi 2957d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2958d18e9008SMiklos Szeredi 2959d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2960d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 29612675a4ebSAl Viro error = -ENOENT; 2962d18e9008SMiklos Szeredi goto out; 2963d18e9008SMiklos Szeredi } 2964d18e9008SMiklos Szeredi 296562b259d8SMiklos Szeredi mode = op->mode; 2966d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2967d18e9008SMiklos Szeredi mode &= ~current_umask(); 2968d18e9008SMiklos Szeredi 2969116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2970116cc022SMiklos Szeredi if (excl) 2971d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2972d18e9008SMiklos Szeredi 2973d18e9008SMiklos Szeredi /* 2974d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2975d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2976d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2977d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2978d18e9008SMiklos Szeredi * 2979d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2980d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2981d18e9008SMiklos Szeredi */ 298264894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 298364894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 298464894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2985d18e9008SMiklos Szeredi /* 2986d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2987d18e9008SMiklos Szeredi * back to lookup + open 2988d18e9008SMiklos Szeredi */ 2989d18e9008SMiklos Szeredi goto no_open; 2990d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2991d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 299264894cf8SAl Viro create_error = -EROFS; 2993d18e9008SMiklos Szeredi goto no_open; 2994d18e9008SMiklos Szeredi } else { 2995d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 299664894cf8SAl Viro create_error = -EROFS; 2997d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2998d18e9008SMiklos Szeredi } 2999d18e9008SMiklos Szeredi } 3000d18e9008SMiklos Szeredi 3001d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 300238227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 3003d18e9008SMiklos Szeredi if (error) { 3004d18e9008SMiklos Szeredi create_error = error; 3005d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 3006d18e9008SMiklos Szeredi goto no_open; 3007d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 3008d18e9008SMiklos Szeredi } 3009d18e9008SMiklos Szeredi } 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; 301630d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 301747237687SAl Viro opened); 3018d9585277SAl Viro if (error < 0) { 3019d9585277SAl Viro if (create_error && error == -ENOENT) 3020d9585277SAl Viro error = create_error; 3021d18e9008SMiklos Szeredi goto out; 3022d18e9008SMiklos Szeredi } 3023d18e9008SMiklos Szeredi 3024d9585277SAl Viro if (error) { /* returned 1, that is */ 302530d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 30262675a4ebSAl Viro error = -EIO; 3027d18e9008SMiklos Szeredi goto out; 3028d18e9008SMiklos Szeredi } 302930d90494SAl Viro if (file->f_path.dentry) { 3030d18e9008SMiklos Szeredi dput(dentry); 303130d90494SAl Viro dentry = file->f_path.dentry; 3032d18e9008SMiklos Szeredi } 303303da633aSAl Viro if (*opened & FILE_CREATED) 303403da633aSAl Viro fsnotify_create(dir, dentry); 303503da633aSAl Viro if (!dentry->d_inode) { 303603da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 303703da633aSAl Viro if (create_error) { 303862b2ce96SSage Weil error = create_error; 303962b2ce96SSage Weil goto out; 304062b2ce96SSage Weil } 304103da633aSAl Viro } else { 304203da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 304303da633aSAl Viro error = -EEXIST; 304403da633aSAl Viro goto out; 304503da633aSAl Viro } 304603da633aSAl Viro } 3047d18e9008SMiklos Szeredi goto looked_up; 3048d18e9008SMiklos Szeredi } 3049d18e9008SMiklos Szeredi 3050d18e9008SMiklos Szeredi /* 3051d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 3052d18e9008SMiklos Szeredi * here. 3053d18e9008SMiklos Szeredi */ 305403da633aSAl Viro acc_mode = op->acc_mode; 305503da633aSAl Viro if (*opened & FILE_CREATED) { 305603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 305703da633aSAl Viro fsnotify_create(dir, dentry); 305862fb4a15SAl Viro acc_mode = 0; 305903da633aSAl Viro } 30602675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 30612675a4ebSAl Viro if (error) 30622675a4ebSAl Viro fput(file); 3063d18e9008SMiklos Szeredi 3064d18e9008SMiklos Szeredi out: 3065d18e9008SMiklos Szeredi dput(dentry); 30662675a4ebSAl Viro return error; 3067d18e9008SMiklos Szeredi 3068d18e9008SMiklos Szeredi no_open: 3069d18e9008SMiklos Szeredi if (need_lookup) { 307072bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 3071d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 30722675a4ebSAl Viro return PTR_ERR(dentry); 307310c64ceaSAl Viro } 307410c64ceaSAl Viro if (create_error && !dentry->d_inode) { 30752675a4ebSAl Viro error = create_error; 3076d18e9008SMiklos Szeredi goto out; 3077d18e9008SMiklos Szeredi } 3078d18e9008SMiklos Szeredi looked_up: 3079d18e9008SMiklos Szeredi path->dentry = dentry; 3080d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30812675a4ebSAl Viro return 1; 3082d18e9008SMiklos Szeredi } 3083d18e9008SMiklos Szeredi 308431e6b01fSNick Piggin /* 30851acf0af9SDavid Howells * Look up and maybe create and open the last component. 3086d58ffd35SMiklos Szeredi * 3087d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3088d58ffd35SMiklos Szeredi * 30891acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30901acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30911acf0af9SDavid Howells * 30921acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30931acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30941acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30951acf0af9SDavid Howells * specified then a negative dentry may be returned. 30961acf0af9SDavid Howells * 30971acf0af9SDavid Howells * An error code is returned otherwise. 30981acf0af9SDavid Howells * 30991acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 31001acf0af9SDavid Howells * cleared otherwise prior to returning. 3101d58ffd35SMiklos Szeredi */ 31022675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 310330d90494SAl Viro struct file *file, 3104d58ffd35SMiklos Szeredi const struct open_flags *op, 310564894cf8SAl Viro bool got_write, int *opened) 3106d58ffd35SMiklos Szeredi { 3107d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 310854ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 3109d58ffd35SMiklos Szeredi struct dentry *dentry; 3110d58ffd35SMiklos Szeredi int error; 31116c51e513SAl Viro bool need_lookup = false; 3112d58ffd35SMiklos Szeredi 311347237687SAl Viro *opened &= ~FILE_CREATED; 31146c51e513SAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags); 3115d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31162675a4ebSAl Viro return PTR_ERR(dentry); 3117d58ffd35SMiklos Szeredi 31186c51e513SAl Viro if (!dentry) { 31196c51e513SAl Viro dentry = d_alloc(dir, &nd->last); 31206c51e513SAl Viro if (unlikely(!dentry)) 31216c51e513SAl Viro return -ENOMEM; 31226c51e513SAl Viro need_lookup = true; 31236c51e513SAl Viro } else if (dentry->d_inode) { 3124d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3125d18e9008SMiklos Szeredi goto out_no_open; 31266c51e513SAl Viro } 3127d18e9008SMiklos Szeredi 3128d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 312964894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 313047237687SAl Viro need_lookup, opened); 3131d18e9008SMiklos Szeredi } 3132d18e9008SMiklos Szeredi 313354ef4872SMiklos Szeredi if (need_lookup) { 313454ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 313554ef4872SMiklos Szeredi 313672bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 313754ef4872SMiklos Szeredi if (IS_ERR(dentry)) 31382675a4ebSAl Viro return PTR_ERR(dentry); 313954ef4872SMiklos Szeredi } 314054ef4872SMiklos Szeredi 3141d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 3142d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 3143d58ffd35SMiklos Szeredi umode_t mode = op->mode; 3144d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 3145d58ffd35SMiklos Szeredi mode &= ~current_umask(); 3146d58ffd35SMiklos Szeredi /* 3147d58ffd35SMiklos Szeredi * This write is needed to ensure that a 3148d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 3149d58ffd35SMiklos Szeredi * the time when the file is created and when 3150d58ffd35SMiklos Szeredi * a permanent write count is taken through 3151015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 3152d58ffd35SMiklos Szeredi */ 315364894cf8SAl Viro if (!got_write) { 315464894cf8SAl Viro error = -EROFS; 3155d58ffd35SMiklos Szeredi goto out_dput; 315664894cf8SAl Viro } 315747237687SAl Viro *opened |= FILE_CREATED; 3158d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 3159d58ffd35SMiklos Szeredi if (error) 3160d58ffd35SMiklos Szeredi goto out_dput; 3161312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 3162312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 3163d58ffd35SMiklos Szeredi if (error) 3164d58ffd35SMiklos Szeredi goto out_dput; 3165d58ffd35SMiklos Szeredi } 3166d18e9008SMiklos Szeredi out_no_open: 3167d58ffd35SMiklos Szeredi path->dentry = dentry; 3168d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31692675a4ebSAl Viro return 1; 3170d58ffd35SMiklos Szeredi 3171d58ffd35SMiklos Szeredi out_dput: 3172d58ffd35SMiklos Szeredi dput(dentry); 31732675a4ebSAl Viro return error; 3174d58ffd35SMiklos Szeredi } 3175d58ffd35SMiklos Szeredi 3176d58ffd35SMiklos Szeredi /* 3177fe2d35ffSAl Viro * Handle the last step of open() 317831e6b01fSNick Piggin */ 3179896475d5SAl Viro static int do_last(struct nameidata *nd, 318030d90494SAl Viro struct file *file, const struct open_flags *op, 318176ae2a5aSAl Viro int *opened) 3182fb1cc555SAl Viro { 3183a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3184ca344a89SAl Viro int open_flag = op->open_flag; 318577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 318664894cf8SAl Viro bool got_write = false; 3187bcda7652SAl Viro int acc_mode = op->acc_mode; 3188254cf582SAl Viro unsigned seq; 3189a1eb3315SMiklos Szeredi struct inode *inode; 319016b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3191896475d5SAl Viro struct path path; 319216b1c1cdSMiklos Szeredi bool retried = false; 319316c2cd71SAl Viro int error; 3194fb1cc555SAl Viro 3195c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3196c3e380b0SAl Viro nd->flags |= op->intent; 3197c3e380b0SAl Viro 3198bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3199fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3200deb106c6SAl Viro if (unlikely(error)) 32012675a4ebSAl Viro return error; 3202e83db167SMiklos Szeredi goto finish_open; 32031f36f774SAl Viro } 3204a2c36b45SAl Viro 3205ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3206fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3207fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3208fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3209254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3210e9742b53SAl Viro if (likely(error > 0)) 321171574865SMiklos Szeredi goto finish_lookup; 321271574865SMiklos Szeredi 3213ce57dfc1SAl Viro if (error < 0) 3214deb106c6SAl Viro return error; 3215a1eb3315SMiklos Szeredi 321637d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32176583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3218b6183df7SMiklos Szeredi } else { 3219fe2d35ffSAl Viro /* create side of things */ 3220a3fbbde7SAl Viro /* 3221b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3222b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3223b6183df7SMiklos Szeredi * about to look up 3224a3fbbde7SAl Viro */ 32259f1fafeeSAl Viro error = complete_walk(nd); 3226e8bb73dfSAl Viro if (error) 32272675a4ebSAl Viro return error; 3228fe2d35ffSAl Viro 322976ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32301f36f774SAl Viro /* trailing slashes? */ 3231deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3232deb106c6SAl Viro return -EISDIR; 3233b6183df7SMiklos Szeredi } 32341f36f774SAl Viro 323516b1c1cdSMiklos Szeredi retry_lookup: 323664894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 323764894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 323864894cf8SAl Viro if (!error) 323964894cf8SAl Viro got_write = true; 324064894cf8SAl Viro /* 324164894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 324264894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 324364894cf8SAl Viro * dropping this one anyway. 324464894cf8SAl Viro */ 324564894cf8SAl Viro } 32465955102cSAl Viro inode_lock(dir->d_inode); 3247896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32485955102cSAl Viro inode_unlock(dir->d_inode); 3249fb1cc555SAl Viro 32502675a4ebSAl Viro if (error <= 0) { 32512675a4ebSAl Viro if (error) 3252d58ffd35SMiklos Szeredi goto out; 32536c0d46c4SAl Viro 325447237687SAl Viro if ((*opened & FILE_CREATED) || 3255496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 325677d660a8SMiklos Szeredi will_truncate = false; 3257d18e9008SMiklos Szeredi 325876ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3259d18e9008SMiklos Szeredi goto opened; 3260d18e9008SMiklos Szeredi } 3261d18e9008SMiklos Szeredi 326247237687SAl Viro if (*opened & FILE_CREATED) { 32639b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3264ca344a89SAl Viro open_flag &= ~O_TRUNC; 326577d660a8SMiklos Szeredi will_truncate = false; 326662fb4a15SAl Viro acc_mode = 0; 3267896475d5SAl Viro path_to_nameidata(&path, nd); 3268e83db167SMiklos Szeredi goto finish_open_created; 3269fb1cc555SAl Viro } 3270fb1cc555SAl Viro 3271fb1cc555SAl Viro /* 3272d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3273d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3274d18e9008SMiklos Szeredi * necessary...) 3275d18e9008SMiklos Szeredi */ 327664894cf8SAl Viro if (got_write) { 3277d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 327864894cf8SAl Viro got_write = false; 3279d18e9008SMiklos Szeredi } 3280d18e9008SMiklos Szeredi 32816583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 32826583fe22SAl Viro path_to_nameidata(&path, nd); 32836583fe22SAl Viro return -ENOENT; 32846583fe22SAl Viro } 32856583fe22SAl Viro 32866583fe22SAl Viro /* 32876583fe22SAl Viro * create/update audit record if it already exists. 32886583fe22SAl Viro */ 32896583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 32906583fe22SAl Viro 3291deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3292deb106c6SAl Viro path_to_nameidata(&path, nd); 3293deb106c6SAl Viro return -EEXIST; 3294deb106c6SAl Viro } 3295fb1cc555SAl Viro 3296756daf26SNeilBrown error = follow_managed(&path, nd); 3297deb106c6SAl Viro if (unlikely(error < 0)) 3298deb106c6SAl Viro return error; 3299a3fbbde7SAl Viro 3300254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3301d4565649SAl Viro inode = d_backing_inode(path.dentry); 3302766c4cbfSAl Viro finish_lookup: 3303191d7f73SAl Viro if (nd->depth) 3304191d7f73SAl Viro put_link(nd); 3305181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3306181548c0SAl Viro inode, seq); 3307deb106c6SAl Viro if (unlikely(error)) 3308d63ff28fSAl Viro return error; 3309fb1cc555SAl Viro 3310896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3311896475d5SAl Viro path_to_nameidata(&path, nd); 331216b1c1cdSMiklos Szeredi } else { 331316b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3314896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3315896475d5SAl Viro nd->path.dentry = path.dentry; 331616b1c1cdSMiklos Szeredi 331716b1c1cdSMiklos Szeredi } 3318decf3400SMiklos Szeredi nd->inode = inode; 3319254cf582SAl Viro nd->seq = seq; 3320a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3321bc77daa7SAl Viro finish_open: 3322a3fbbde7SAl Viro error = complete_walk(nd); 332316b1c1cdSMiklos Szeredi if (error) { 332416b1c1cdSMiklos Szeredi path_put(&save_parent); 33252675a4ebSAl Viro return error; 332616b1c1cdSMiklos Szeredi } 332776ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 33285129fa48SAl Viro if (unlikely(d_is_symlink(nd->path.dentry)) && !(open_flag & O_PATH)) { 33295129fa48SAl Viro error = -ELOOP; 33305129fa48SAl Viro goto out; 33315129fa48SAl Viro } 3332fb1cc555SAl Viro error = -EISDIR; 333344b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33342675a4ebSAl Viro goto out; 3335af2f5542SMiklos Szeredi error = -ENOTDIR; 333644b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33372675a4ebSAl Viro goto out; 33384bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 333977d660a8SMiklos Szeredi will_truncate = false; 33406c0d46c4SAl Viro 33410f9d1a10SAl Viro if (will_truncate) { 33420f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33430f9d1a10SAl Viro if (error) 33442675a4ebSAl Viro goto out; 334564894cf8SAl Viro got_write = true; 33460f9d1a10SAl Viro } 3347e83db167SMiklos Szeredi finish_open_created: 334862fb4a15SAl Viro if (likely(!(open_flag & O_PATH))) { 3349bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3350ca344a89SAl Viro if (error) 33512675a4ebSAl Viro goto out; 335262fb4a15SAl Viro } 33534aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33544aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 33554aa7c634SMiklos Szeredi if (!error) { 33564aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 33574aa7c634SMiklos Szeredi } else { 335830d90494SAl Viro if (error == -EOPENSTALE) 3359f60dc3dbSMiklos Szeredi goto stale_open; 3360015c3bbcSMiklos Szeredi goto out; 3361f60dc3dbSMiklos Szeredi } 3362a8277b9bSMiklos Szeredi opened: 33632675a4ebSAl Viro error = open_check_o_direct(file); 3364015c3bbcSMiklos Szeredi if (error) 3365015c3bbcSMiklos Szeredi goto exit_fput; 33663034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3367aa4caadbSMiklos Szeredi if (error) 3368aa4caadbSMiklos Szeredi goto exit_fput; 3369aa4caadbSMiklos Szeredi 33700f9d1a10SAl Viro if (will_truncate) { 33712675a4ebSAl Viro error = handle_truncate(file); 3372aa4caadbSMiklos Szeredi if (error) 3373aa4caadbSMiklos Szeredi goto exit_fput; 33740f9d1a10SAl Viro } 3375ca344a89SAl Viro out: 3376c80567c8SAl Viro if (unlikely(error > 0)) { 3377c80567c8SAl Viro WARN_ON(1); 3378c80567c8SAl Viro error = -EINVAL; 3379c80567c8SAl Viro } 338064894cf8SAl Viro if (got_write) 33810f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 338216b1c1cdSMiklos Szeredi path_put(&save_parent); 33832675a4ebSAl Viro return error; 3384fb1cc555SAl Viro 3385015c3bbcSMiklos Szeredi exit_fput: 33862675a4ebSAl Viro fput(file); 33872675a4ebSAl Viro goto out; 3388015c3bbcSMiklos Szeredi 3389f60dc3dbSMiklos Szeredi stale_open: 3390f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3391f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3392f60dc3dbSMiklos Szeredi goto out; 3393f60dc3dbSMiklos Szeredi 3394f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3395f60dc3dbSMiklos Szeredi path_put(&nd->path); 3396f60dc3dbSMiklos Szeredi nd->path = save_parent; 3397f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3398f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3399f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 340064894cf8SAl Viro if (got_write) { 3401f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 340264894cf8SAl Viro got_write = false; 3403f60dc3dbSMiklos Szeredi } 3404f60dc3dbSMiklos Szeredi retried = true; 3405f60dc3dbSMiklos Szeredi goto retry_lookup; 3406fb1cc555SAl Viro } 3407fb1cc555SAl Viro 3408c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 340960545d0dSAl Viro const struct open_flags *op, 341060545d0dSAl Viro struct file *file, int *opened) 341160545d0dSAl Viro { 341260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3413625b6d10SAl Viro struct dentry *child; 341460545d0dSAl Viro struct inode *dir; 3415625b6d10SAl Viro struct path path; 3416c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 341760545d0dSAl Viro if (unlikely(error)) 341860545d0dSAl Viro return error; 3419625b6d10SAl Viro error = mnt_want_write(path.mnt); 342060545d0dSAl Viro if (unlikely(error)) 342160545d0dSAl Viro goto out; 3422625b6d10SAl Viro dir = path.dentry->d_inode; 342360545d0dSAl Viro /* we want directory to be writable */ 3424625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 342560545d0dSAl Viro if (error) 342660545d0dSAl Viro goto out2; 342760545d0dSAl Viro if (!dir->i_op->tmpfile) { 342860545d0dSAl Viro error = -EOPNOTSUPP; 342960545d0dSAl Viro goto out2; 343060545d0dSAl Viro } 3431625b6d10SAl Viro child = d_alloc(path.dentry, &name); 343260545d0dSAl Viro if (unlikely(!child)) { 343360545d0dSAl Viro error = -ENOMEM; 343460545d0dSAl Viro goto out2; 343560545d0dSAl Viro } 3436625b6d10SAl Viro dput(path.dentry); 3437625b6d10SAl Viro path.dentry = child; 3438625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 343960545d0dSAl Viro if (error) 344060545d0dSAl Viro goto out2; 3441c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 344269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 344362fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 344460545d0dSAl Viro if (error) 344560545d0dSAl Viro goto out2; 3446625b6d10SAl Viro file->f_path.mnt = path.mnt; 3447625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 344860545d0dSAl Viro if (error) 344960545d0dSAl Viro goto out2; 345060545d0dSAl Viro error = open_check_o_direct(file); 3451f4e0c30cSAl Viro if (error) { 345260545d0dSAl Viro fput(file); 3453f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3454f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3455f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3456f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3457f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3458f4e0c30cSAl Viro } 345960545d0dSAl Viro out2: 3460625b6d10SAl Viro mnt_drop_write(path.mnt); 346160545d0dSAl Viro out: 3462625b6d10SAl Viro path_put(&path); 346360545d0dSAl Viro return error; 346460545d0dSAl Viro } 346560545d0dSAl Viro 3466c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3467c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34681da177e4SLinus Torvalds { 3469368ee9baSAl Viro const char *s; 347030d90494SAl Viro struct file *file; 347147237687SAl Viro int opened = 0; 347213aab428SAl Viro int error; 347331e6b01fSNick Piggin 347430d90494SAl Viro file = get_empty_filp(); 34751afc99beSAl Viro if (IS_ERR(file)) 34761afc99beSAl Viro return file; 347731e6b01fSNick Piggin 347830d90494SAl Viro file->f_flags = op->open_flag; 347931e6b01fSNick Piggin 3480bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3481c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3482f15133dfSAl Viro goto out2; 348360545d0dSAl Viro } 348460545d0dSAl Viro 3485c8a53ee5SAl Viro s = path_init(nd, flags); 3486368ee9baSAl Viro if (IS_ERR(s)) { 3487368ee9baSAl Viro put_filp(file); 3488368ee9baSAl Viro return ERR_CAST(s); 3489368ee9baSAl Viro } 34903bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 349176ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 349273d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 34933bdba28bSAl Viro s = trailing_symlink(nd); 34943bdba28bSAl Viro if (IS_ERR(s)) { 34953bdba28bSAl Viro error = PTR_ERR(s); 34962675a4ebSAl Viro break; 3497806b681cSAl Viro } 34983bdba28bSAl Viro } 3499deb106c6SAl Viro terminate_walk(nd); 3500f15133dfSAl Viro out2: 35012675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35022675a4ebSAl Viro BUG_ON(!error); 350330d90494SAl Viro put_filp(file); 3504015c3bbcSMiklos Szeredi } 35052675a4ebSAl Viro if (unlikely(error)) { 35062675a4ebSAl Viro if (error == -EOPENSTALE) { 35072675a4ebSAl Viro if (flags & LOOKUP_RCU) 35082675a4ebSAl Viro error = -ECHILD; 35092675a4ebSAl Viro else 35102675a4ebSAl Viro error = -ESTALE; 35112675a4ebSAl Viro } 35122675a4ebSAl Viro file = ERR_PTR(error); 35132675a4ebSAl Viro } 35142675a4ebSAl Viro return file; 3515de459215SKirill Korotaev } 35161da177e4SLinus Torvalds 3517669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3518f9652e10SAl Viro const struct open_flags *op) 351913aab428SAl Viro { 35209883d185SAl Viro struct nameidata nd; 3521f9652e10SAl Viro int flags = op->lookup_flags; 352213aab428SAl Viro struct file *filp; 352313aab428SAl Viro 35249883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3525c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 352613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3527c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 352813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3529c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35309883d185SAl Viro restore_nameidata(); 353113aab428SAl Viro return filp; 353213aab428SAl Viro } 353313aab428SAl Viro 353473d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3535f9652e10SAl Viro const char *name, const struct open_flags *op) 353673d049a4SAl Viro { 35379883d185SAl Viro struct nameidata nd; 353873d049a4SAl Viro struct file *file; 353951689104SPaul Moore struct filename *filename; 3540f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 354173d049a4SAl Viro 354273d049a4SAl Viro nd.root.mnt = mnt; 354373d049a4SAl Viro nd.root.dentry = dentry; 354473d049a4SAl Viro 3545b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 354673d049a4SAl Viro return ERR_PTR(-ELOOP); 354773d049a4SAl Viro 354851689104SPaul Moore filename = getname_kernel(name); 3549a1c83681SViresh Kumar if (IS_ERR(filename)) 355051689104SPaul Moore return ERR_CAST(filename); 355151689104SPaul Moore 35529883d185SAl Viro set_nameidata(&nd, -1, filename); 3553c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 355473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3555c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 355673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3557c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35589883d185SAl Viro restore_nameidata(); 355951689104SPaul Moore putname(filename); 356073d049a4SAl Viro return file; 356173d049a4SAl Viro } 356273d049a4SAl Viro 3563fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35641ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35651da177e4SLinus Torvalds { 3566c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3567391172c4SAl Viro struct qstr last; 3568391172c4SAl Viro int type; 3569c30dabfeSJan Kara int err2; 35701ac12b4bSJeff Layton int error; 35711ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35721ac12b4bSJeff Layton 35731ac12b4bSJeff Layton /* 35741ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35751ac12b4bSJeff Layton * other flags passed in are ignored! 35761ac12b4bSJeff Layton */ 35771ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35781ac12b4bSJeff Layton 35795c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35805c31b6ceSAl Viro if (IS_ERR(name)) 35815c31b6ceSAl Viro return ERR_CAST(name); 35821da177e4SLinus Torvalds 3583c663e5d8SChristoph Hellwig /* 3584c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3585c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3586c663e5d8SChristoph Hellwig */ 35875c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3588ed75e95dSAl Viro goto out; 3589c663e5d8SChristoph Hellwig 3590c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3591391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3592c663e5d8SChristoph Hellwig /* 3593c663e5d8SChristoph Hellwig * Do the final lookup. 3594c663e5d8SChristoph Hellwig */ 3595391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35965955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3597391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35981da177e4SLinus Torvalds if (IS_ERR(dentry)) 3599a8104a9fSAl Viro goto unlock; 3600c663e5d8SChristoph Hellwig 3601a8104a9fSAl Viro error = -EEXIST; 3602b18825a7SDavid Howells if (d_is_positive(dentry)) 3603a8104a9fSAl Viro goto fail; 3604b18825a7SDavid Howells 3605c663e5d8SChristoph Hellwig /* 3606c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3607c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3608c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3609c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3610c663e5d8SChristoph Hellwig */ 3611391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3612a8104a9fSAl Viro error = -ENOENT; 3613ed75e95dSAl Viro goto fail; 3614e9baf6e5SAl Viro } 3615c30dabfeSJan Kara if (unlikely(err2)) { 3616c30dabfeSJan Kara error = err2; 3617a8104a9fSAl Viro goto fail; 3618c30dabfeSJan Kara } 3619181c37b6SAl Viro putname(name); 3620e9baf6e5SAl Viro return dentry; 36211da177e4SLinus Torvalds fail: 3622a8104a9fSAl Viro dput(dentry); 3623a8104a9fSAl Viro dentry = ERR_PTR(error); 3624a8104a9fSAl Viro unlock: 36255955102cSAl Viro inode_unlock(path->dentry->d_inode); 3626c30dabfeSJan Kara if (!err2) 3627391172c4SAl Viro mnt_drop_write(path->mnt); 3628ed75e95dSAl Viro out: 3629391172c4SAl Viro path_put(path); 3630181c37b6SAl Viro putname(name); 3631ed75e95dSAl Viro return dentry; 3632dae6ad8fSAl Viro } 3633fa14a0b8SAl Viro 3634fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3635fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3636fa14a0b8SAl Viro { 3637181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3638181c37b6SAl Viro path, lookup_flags); 3639fa14a0b8SAl Viro } 3640dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3641dae6ad8fSAl Viro 3642921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3643921a1650SAl Viro { 3644921a1650SAl Viro dput(dentry); 36455955102cSAl Viro inode_unlock(path->dentry->d_inode); 3646a8104a9fSAl Viro mnt_drop_write(path->mnt); 3647921a1650SAl Viro path_put(path); 3648921a1650SAl Viro } 3649921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3650921a1650SAl Viro 3651520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36521ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3653dae6ad8fSAl Viro { 3654181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3655dae6ad8fSAl Viro } 3656dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3657dae6ad8fSAl Viro 36581a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36591da177e4SLinus Torvalds { 3660a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36611da177e4SLinus Torvalds 36621da177e4SLinus Torvalds if (error) 36631da177e4SLinus Torvalds return error; 36641da177e4SLinus Torvalds 3665975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36661da177e4SLinus Torvalds return -EPERM; 36671da177e4SLinus Torvalds 3668acfa4380SAl Viro if (!dir->i_op->mknod) 36691da177e4SLinus Torvalds return -EPERM; 36701da177e4SLinus Torvalds 367108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 367208ce5f16SSerge E. Hallyn if (error) 367308ce5f16SSerge E. Hallyn return error; 367408ce5f16SSerge E. Hallyn 36751da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36761da177e4SLinus Torvalds if (error) 36771da177e4SLinus Torvalds return error; 36781da177e4SLinus Torvalds 36791da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3680a74574aaSStephen Smalley if (!error) 3681f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36821da177e4SLinus Torvalds return error; 36831da177e4SLinus Torvalds } 36844d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36851da177e4SLinus Torvalds 3686f69aac00SAl Viro static int may_mknod(umode_t mode) 3687463c3197SDave Hansen { 3688463c3197SDave Hansen switch (mode & S_IFMT) { 3689463c3197SDave Hansen case S_IFREG: 3690463c3197SDave Hansen case S_IFCHR: 3691463c3197SDave Hansen case S_IFBLK: 3692463c3197SDave Hansen case S_IFIFO: 3693463c3197SDave Hansen case S_IFSOCK: 3694463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3695463c3197SDave Hansen return 0; 3696463c3197SDave Hansen case S_IFDIR: 3697463c3197SDave Hansen return -EPERM; 3698463c3197SDave Hansen default: 3699463c3197SDave Hansen return -EINVAL; 3700463c3197SDave Hansen } 3701463c3197SDave Hansen } 3702463c3197SDave Hansen 37038208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37042e4d0924SHeiko Carstens unsigned, dev) 37051da177e4SLinus Torvalds { 37061da177e4SLinus Torvalds struct dentry *dentry; 3707dae6ad8fSAl Viro struct path path; 3708dae6ad8fSAl Viro int error; 3709972567f1SJeff Layton unsigned int lookup_flags = 0; 37101da177e4SLinus Torvalds 37118e4bfca1SAl Viro error = may_mknod(mode); 37128e4bfca1SAl Viro if (error) 37138e4bfca1SAl Viro return error; 3714972567f1SJeff Layton retry: 3715972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3716dae6ad8fSAl Viro if (IS_ERR(dentry)) 3717dae6ad8fSAl Viro return PTR_ERR(dentry); 37182ad94ae6SAl Viro 3719dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3720ce3b0f8dSAl Viro mode &= ~current_umask(); 3721dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3722be6d3e56SKentaro Takeda if (error) 3723a8104a9fSAl Viro goto out; 37241da177e4SLinus Torvalds switch (mode & S_IFMT) { 37251da177e4SLinus Torvalds case 0: case S_IFREG: 3726312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 37271da177e4SLinus Torvalds break; 37281da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3729dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37301da177e4SLinus Torvalds new_decode_dev(dev)); 37311da177e4SLinus Torvalds break; 37321da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3733dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37341da177e4SLinus Torvalds break; 37351da177e4SLinus Torvalds } 3736a8104a9fSAl Viro out: 3737921a1650SAl Viro done_path_create(&path, dentry); 3738972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3739972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3740972567f1SJeff Layton goto retry; 3741972567f1SJeff Layton } 37421da177e4SLinus Torvalds return error; 37431da177e4SLinus Torvalds } 37441da177e4SLinus Torvalds 37458208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37465590ff0dSUlrich Drepper { 37475590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37485590ff0dSUlrich Drepper } 37495590ff0dSUlrich Drepper 375018bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37511da177e4SLinus Torvalds { 3752a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37538de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37541da177e4SLinus Torvalds 37551da177e4SLinus Torvalds if (error) 37561da177e4SLinus Torvalds return error; 37571da177e4SLinus Torvalds 3758acfa4380SAl Viro if (!dir->i_op->mkdir) 37591da177e4SLinus Torvalds return -EPERM; 37601da177e4SLinus Torvalds 37611da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37621da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37631da177e4SLinus Torvalds if (error) 37641da177e4SLinus Torvalds return error; 37651da177e4SLinus Torvalds 37668de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37678de52778SAl Viro return -EMLINK; 37688de52778SAl Viro 37691da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3770a74574aaSStephen Smalley if (!error) 3771f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37721da177e4SLinus Torvalds return error; 37731da177e4SLinus Torvalds } 37744d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37751da177e4SLinus Torvalds 3776a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37771da177e4SLinus Torvalds { 37786902d925SDave Hansen struct dentry *dentry; 3779dae6ad8fSAl Viro struct path path; 3780dae6ad8fSAl Viro int error; 3781b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37821da177e4SLinus Torvalds 3783b76d8b82SJeff Layton retry: 3784b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37856902d925SDave Hansen if (IS_ERR(dentry)) 3786dae6ad8fSAl Viro return PTR_ERR(dentry); 37876902d925SDave Hansen 3788dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3789ce3b0f8dSAl Viro mode &= ~current_umask(); 3790dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3791a8104a9fSAl Viro if (!error) 3792dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3793921a1650SAl Viro done_path_create(&path, dentry); 3794b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3795b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3796b76d8b82SJeff Layton goto retry; 3797b76d8b82SJeff Layton } 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds } 38001da177e4SLinus Torvalds 3801a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38025590ff0dSUlrich Drepper { 38035590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38045590ff0dSUlrich Drepper } 38055590ff0dSUlrich Drepper 38061da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38071da177e4SLinus Torvalds { 38081da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38091da177e4SLinus Torvalds 38101da177e4SLinus Torvalds if (error) 38111da177e4SLinus Torvalds return error; 38121da177e4SLinus Torvalds 3813acfa4380SAl Viro if (!dir->i_op->rmdir) 38141da177e4SLinus Torvalds return -EPERM; 38151da177e4SLinus Torvalds 38161d2ef590SAl Viro dget(dentry); 38175955102cSAl Viro inode_lock(dentry->d_inode); 3818912dbc15SSage Weil 38191da177e4SLinus Torvalds error = -EBUSY; 38207af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3821912dbc15SSage Weil goto out; 3822912dbc15SSage Weil 38231da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3824912dbc15SSage Weil if (error) 3825912dbc15SSage Weil goto out; 3826912dbc15SSage Weil 38273cebde24SSage Weil shrink_dcache_parent(dentry); 38281da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3829912dbc15SSage Weil if (error) 3830912dbc15SSage Weil goto out; 3831912dbc15SSage Weil 38321da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3833d83c49f3SAl Viro dont_mount(dentry); 38348ed936b5SEric W. Biederman detach_mounts(dentry); 38351da177e4SLinus Torvalds 3836912dbc15SSage Weil out: 38375955102cSAl Viro inode_unlock(dentry->d_inode); 38381d2ef590SAl Viro dput(dentry); 3839912dbc15SSage Weil if (!error) 3840912dbc15SSage Weil d_delete(dentry); 38411da177e4SLinus Torvalds return error; 38421da177e4SLinus Torvalds } 38434d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38441da177e4SLinus Torvalds 38455590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38461da177e4SLinus Torvalds { 38471da177e4SLinus Torvalds int error = 0; 384891a27b2aSJeff Layton struct filename *name; 38491da177e4SLinus Torvalds struct dentry *dentry; 3850f5beed75SAl Viro struct path path; 3851f5beed75SAl Viro struct qstr last; 3852f5beed75SAl Viro int type; 3853c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3854c6ee9206SJeff Layton retry: 3855f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3856f5beed75SAl Viro &path, &last, &type, lookup_flags); 385791a27b2aSJeff Layton if (IS_ERR(name)) 385891a27b2aSJeff Layton return PTR_ERR(name); 38591da177e4SLinus Torvalds 3860f5beed75SAl Viro switch (type) { 38611da177e4SLinus Torvalds case LAST_DOTDOT: 38621da177e4SLinus Torvalds error = -ENOTEMPTY; 38631da177e4SLinus Torvalds goto exit1; 38641da177e4SLinus Torvalds case LAST_DOT: 38651da177e4SLinus Torvalds error = -EINVAL; 38661da177e4SLinus Torvalds goto exit1; 38671da177e4SLinus Torvalds case LAST_ROOT: 38681da177e4SLinus Torvalds error = -EBUSY; 38691da177e4SLinus Torvalds goto exit1; 38701da177e4SLinus Torvalds } 38710612d9fbSOGAWA Hirofumi 3872f5beed75SAl Viro error = mnt_want_write(path.mnt); 3873c30dabfeSJan Kara if (error) 3874c30dabfeSJan Kara goto exit1; 38750612d9fbSOGAWA Hirofumi 38765955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3877f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38781da177e4SLinus Torvalds error = PTR_ERR(dentry); 38796902d925SDave Hansen if (IS_ERR(dentry)) 38806902d925SDave Hansen goto exit2; 3881e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3882e6bc45d6STheodore Ts'o error = -ENOENT; 3883e6bc45d6STheodore Ts'o goto exit3; 3884e6bc45d6STheodore Ts'o } 3885f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3886be6d3e56SKentaro Takeda if (error) 3887c30dabfeSJan Kara goto exit3; 3888f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38890622753bSDave Hansen exit3: 38901da177e4SLinus Torvalds dput(dentry); 38916902d925SDave Hansen exit2: 38925955102cSAl Viro inode_unlock(path.dentry->d_inode); 3893f5beed75SAl Viro mnt_drop_write(path.mnt); 38941da177e4SLinus Torvalds exit1: 3895f5beed75SAl Viro path_put(&path); 38961da177e4SLinus Torvalds putname(name); 3897c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3898c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3899c6ee9206SJeff Layton goto retry; 3900c6ee9206SJeff Layton } 39011da177e4SLinus Torvalds return error; 39021da177e4SLinus Torvalds } 39031da177e4SLinus Torvalds 39043cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39055590ff0dSUlrich Drepper { 39065590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39075590ff0dSUlrich Drepper } 39085590ff0dSUlrich Drepper 3909b21996e3SJ. Bruce Fields /** 3910b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3911b21996e3SJ. Bruce Fields * @dir: parent directory 3912b21996e3SJ. Bruce Fields * @dentry: victim 3913b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3914b21996e3SJ. Bruce Fields * 3915b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3916b21996e3SJ. Bruce Fields * 3917b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3918b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3919b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3920b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3921b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3922b21996e3SJ. Bruce Fields * 3923b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3924b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3925b21996e3SJ. Bruce Fields * to be NFS exported. 3926b21996e3SJ. Bruce Fields */ 3927b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39281da177e4SLinus Torvalds { 39299accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39301da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39311da177e4SLinus Torvalds 39321da177e4SLinus Torvalds if (error) 39331da177e4SLinus Torvalds return error; 39341da177e4SLinus Torvalds 3935acfa4380SAl Viro if (!dir->i_op->unlink) 39361da177e4SLinus Torvalds return -EPERM; 39371da177e4SLinus Torvalds 39385955102cSAl Viro inode_lock(target); 39398ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39401da177e4SLinus Torvalds error = -EBUSY; 39411da177e4SLinus Torvalds else { 39421da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3943bec1052eSAl Viro if (!error) { 39445a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39455a14696cSJ. Bruce Fields if (error) 3946b21996e3SJ. Bruce Fields goto out; 39471da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39488ed936b5SEric W. Biederman if (!error) { 3949d83c49f3SAl Viro dont_mount(dentry); 39508ed936b5SEric W. Biederman detach_mounts(dentry); 39518ed936b5SEric W. Biederman } 3952bec1052eSAl Viro } 39531da177e4SLinus Torvalds } 3954b21996e3SJ. Bruce Fields out: 39555955102cSAl Viro inode_unlock(target); 39561da177e4SLinus Torvalds 39571da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39581da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39599accbb97SJ. Bruce Fields fsnotify_link_count(target); 39601da177e4SLinus Torvalds d_delete(dentry); 39611da177e4SLinus Torvalds } 39620eeca283SRobert Love 39631da177e4SLinus Torvalds return error; 39641da177e4SLinus Torvalds } 39654d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39661da177e4SLinus Torvalds 39671da177e4SLinus Torvalds /* 39681da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39691b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39701da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39711da177e4SLinus Torvalds * while waiting on the I/O. 39721da177e4SLinus Torvalds */ 39735590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 39741da177e4SLinus Torvalds { 39752ad94ae6SAl Viro int error; 397691a27b2aSJeff Layton struct filename *name; 39771da177e4SLinus Torvalds struct dentry *dentry; 3978f5beed75SAl Viro struct path path; 3979f5beed75SAl Viro struct qstr last; 3980f5beed75SAl Viro int type; 39811da177e4SLinus Torvalds struct inode *inode = NULL; 3982b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39835d18f813SJeff Layton unsigned int lookup_flags = 0; 39845d18f813SJeff Layton retry: 3985f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3986f5beed75SAl Viro &path, &last, &type, lookup_flags); 398791a27b2aSJeff Layton if (IS_ERR(name)) 398891a27b2aSJeff Layton return PTR_ERR(name); 39892ad94ae6SAl Viro 39901da177e4SLinus Torvalds error = -EISDIR; 3991f5beed75SAl Viro if (type != LAST_NORM) 39921da177e4SLinus Torvalds goto exit1; 39930612d9fbSOGAWA Hirofumi 3994f5beed75SAl Viro error = mnt_want_write(path.mnt); 3995c30dabfeSJan Kara if (error) 3996c30dabfeSJan Kara goto exit1; 3997b21996e3SJ. Bruce Fields retry_deleg: 39985955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3999f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40001da177e4SLinus Torvalds error = PTR_ERR(dentry); 40011da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40021da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4003f5beed75SAl Viro if (last.name[last.len]) 400450338b88STörök Edwin goto slashes; 40051da177e4SLinus Torvalds inode = dentry->d_inode; 4006b18825a7SDavid Howells if (d_is_negative(dentry)) 4007e6bc45d6STheodore Ts'o goto slashes; 40087de9c6eeSAl Viro ihold(inode); 4009f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4010be6d3e56SKentaro Takeda if (error) 4011c30dabfeSJan Kara goto exit2; 4012f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40131da177e4SLinus Torvalds exit2: 40141da177e4SLinus Torvalds dput(dentry); 40151da177e4SLinus Torvalds } 40165955102cSAl Viro inode_unlock(path.dentry->d_inode); 40171da177e4SLinus Torvalds if (inode) 40181da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4019b21996e3SJ. Bruce Fields inode = NULL; 4020b21996e3SJ. Bruce Fields if (delegated_inode) { 40215a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4022b21996e3SJ. Bruce Fields if (!error) 4023b21996e3SJ. Bruce Fields goto retry_deleg; 4024b21996e3SJ. Bruce Fields } 4025f5beed75SAl Viro mnt_drop_write(path.mnt); 40261da177e4SLinus Torvalds exit1: 4027f5beed75SAl Viro path_put(&path); 40281da177e4SLinus Torvalds putname(name); 40295d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40305d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40315d18f813SJeff Layton inode = NULL; 40325d18f813SJeff Layton goto retry; 40335d18f813SJeff Layton } 40341da177e4SLinus Torvalds return error; 40351da177e4SLinus Torvalds 40361da177e4SLinus Torvalds slashes: 4037b18825a7SDavid Howells if (d_is_negative(dentry)) 4038b18825a7SDavid Howells error = -ENOENT; 403944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4040b18825a7SDavid Howells error = -EISDIR; 4041b18825a7SDavid Howells else 4042b18825a7SDavid Howells error = -ENOTDIR; 40431da177e4SLinus Torvalds goto exit2; 40441da177e4SLinus Torvalds } 40451da177e4SLinus Torvalds 40462e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40475590ff0dSUlrich Drepper { 40485590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40495590ff0dSUlrich Drepper return -EINVAL; 40505590ff0dSUlrich Drepper 40515590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40525590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40535590ff0dSUlrich Drepper 40545590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40555590ff0dSUlrich Drepper } 40565590ff0dSUlrich Drepper 40573480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40585590ff0dSUlrich Drepper { 40595590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40605590ff0dSUlrich Drepper } 40615590ff0dSUlrich Drepper 4062db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40631da177e4SLinus Torvalds { 4064a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40651da177e4SLinus Torvalds 40661da177e4SLinus Torvalds if (error) 40671da177e4SLinus Torvalds return error; 40681da177e4SLinus Torvalds 4069acfa4380SAl Viro if (!dir->i_op->symlink) 40701da177e4SLinus Torvalds return -EPERM; 40711da177e4SLinus Torvalds 40721da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40731da177e4SLinus Torvalds if (error) 40741da177e4SLinus Torvalds return error; 40751da177e4SLinus Torvalds 40761da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4077a74574aaSStephen Smalley if (!error) 4078f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40791da177e4SLinus Torvalds return error; 40801da177e4SLinus Torvalds } 40814d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40821da177e4SLinus Torvalds 40832e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40842e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40851da177e4SLinus Torvalds { 40862ad94ae6SAl Viro int error; 408791a27b2aSJeff Layton struct filename *from; 40886902d925SDave Hansen struct dentry *dentry; 4089dae6ad8fSAl Viro struct path path; 4090f46d3567SJeff Layton unsigned int lookup_flags = 0; 40911da177e4SLinus Torvalds 40921da177e4SLinus Torvalds from = getname(oldname); 40931da177e4SLinus Torvalds if (IS_ERR(from)) 40941da177e4SLinus Torvalds return PTR_ERR(from); 4095f46d3567SJeff Layton retry: 4096f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40971da177e4SLinus Torvalds error = PTR_ERR(dentry); 40986902d925SDave Hansen if (IS_ERR(dentry)) 4099dae6ad8fSAl Viro goto out_putname; 41006902d925SDave Hansen 410191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4102a8104a9fSAl Viro if (!error) 410391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4104921a1650SAl Viro done_path_create(&path, dentry); 4105f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4106f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4107f46d3567SJeff Layton goto retry; 4108f46d3567SJeff Layton } 41096902d925SDave Hansen out_putname: 41101da177e4SLinus Torvalds putname(from); 41111da177e4SLinus Torvalds return error; 41121da177e4SLinus Torvalds } 41131da177e4SLinus Torvalds 41143480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41155590ff0dSUlrich Drepper { 41165590ff0dSUlrich Drepper return sys_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; 4159acfa4380SAl Viro if (!dir->i_op->link) 41601da177e4SLinus Torvalds return -EPERM; 41617e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41621da177e4SLinus Torvalds return -EPERM; 41631da177e4SLinus Torvalds 41641da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41651da177e4SLinus Torvalds if (error) 41661da177e4SLinus Torvalds return error; 41671da177e4SLinus Torvalds 41685955102cSAl Viro inode_lock(inode); 4169aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4170f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4171aae8a97dSAneesh Kumar K.V error = -ENOENT; 41728de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41738de52778SAl Viro error = -EMLINK; 4174146a8595SJ. Bruce Fields else { 4175146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4176146a8595SJ. Bruce Fields if (!error) 41771da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4178146a8595SJ. Bruce Fields } 4179f4e0c30cSAl Viro 4180f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4181f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4182f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4183f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4184f4e0c30cSAl Viro } 41855955102cSAl Viro inode_unlock(inode); 4186e31e14ecSStephen Smalley if (!error) 41877e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41881da177e4SLinus Torvalds return error; 41891da177e4SLinus Torvalds } 41904d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41911da177e4SLinus Torvalds 41921da177e4SLinus Torvalds /* 41931da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41941da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41951da177e4SLinus Torvalds * newname. --KAB 41961da177e4SLinus Torvalds * 41971da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41981da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41991da177e4SLinus Torvalds * and other special files. --ADM 42001da177e4SLinus Torvalds */ 42012e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42022e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42031da177e4SLinus Torvalds { 42041da177e4SLinus Torvalds struct dentry *new_dentry; 4205dae6ad8fSAl Viro struct path old_path, new_path; 4206146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 420711a7b371SAneesh Kumar K.V int how = 0; 42081da177e4SLinus Torvalds int error; 42091da177e4SLinus Torvalds 421011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4211c04030e1SUlrich Drepper return -EINVAL; 421211a7b371SAneesh Kumar K.V /* 4213f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4214f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4215f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 421611a7b371SAneesh Kumar K.V */ 4217f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4218f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4219f0cc6ffbSLinus Torvalds return -ENOENT; 422011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4221f0cc6ffbSLinus Torvalds } 4222c04030e1SUlrich Drepper 422311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 422411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4225442e31caSJeff Layton retry: 422611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42271da177e4SLinus Torvalds if (error) 42282ad94ae6SAl Viro return error; 42292ad94ae6SAl Viro 4230442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4231442e31caSJeff Layton (how & LOOKUP_REVAL)); 42321da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42336902d925SDave Hansen if (IS_ERR(new_dentry)) 4234dae6ad8fSAl Viro goto out; 4235dae6ad8fSAl Viro 4236dae6ad8fSAl Viro error = -EXDEV; 4237dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4238dae6ad8fSAl Viro goto out_dput; 4239800179c9SKees Cook error = may_linkat(&old_path); 4240800179c9SKees Cook if (unlikely(error)) 4241800179c9SKees Cook goto out_dput; 4242dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4243be6d3e56SKentaro Takeda if (error) 4244a8104a9fSAl Viro goto out_dput; 4245146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 424675c3f29dSDave Hansen out_dput: 4247921a1650SAl Viro done_path_create(&new_path, new_dentry); 4248146a8595SJ. Bruce Fields if (delegated_inode) { 4249146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4250d22e6338SOleg Drokin if (!error) { 4251d22e6338SOleg Drokin path_put(&old_path); 4252146a8595SJ. Bruce Fields goto retry; 4253146a8595SJ. Bruce Fields } 4254d22e6338SOleg Drokin } 4255442e31caSJeff Layton if (retry_estale(error, how)) { 4256d22e6338SOleg Drokin path_put(&old_path); 4257442e31caSJeff Layton how |= LOOKUP_REVAL; 4258442e31caSJeff Layton goto retry; 4259442e31caSJeff Layton } 42601da177e4SLinus Torvalds out: 42612d8f3038SAl Viro path_put(&old_path); 42621da177e4SLinus Torvalds 42631da177e4SLinus Torvalds return error; 42641da177e4SLinus Torvalds } 42651da177e4SLinus Torvalds 42663480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42675590ff0dSUlrich Drepper { 4268c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42695590ff0dSUlrich Drepper } 42705590ff0dSUlrich Drepper 4271bc27027aSMiklos Szeredi /** 4272bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4273bc27027aSMiklos Szeredi * @old_dir: parent of source 4274bc27027aSMiklos Szeredi * @old_dentry: source 4275bc27027aSMiklos Szeredi * @new_dir: parent of destination 4276bc27027aSMiklos Szeredi * @new_dentry: destination 4277bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4278520c8b16SMiklos Szeredi * @flags: rename flags 4279bc27027aSMiklos Szeredi * 4280bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4281bc27027aSMiklos Szeredi * 4282bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4283bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4284bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4285bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4286bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4287bc27027aSMiklos Szeredi * so. 4288bc27027aSMiklos Szeredi * 4289bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4290bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4291bc27027aSMiklos Szeredi * to be NFS exported. 4292bc27027aSMiklos Szeredi * 42931da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42941da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42951da177e4SLinus Torvalds * Problems: 4296d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42971da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42981da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4299a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43001da177e4SLinus Torvalds * story. 43016cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43026cedba89SJ. Bruce Fields * and source (if it is not a directory). 43031b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43041da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43051da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4306a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43071da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43081da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43091da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4310a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43111da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43121da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43131da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4314e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43151b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43161da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4317c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43181da177e4SLinus Torvalds * locking]. 43191da177e4SLinus Torvalds */ 43201da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43218e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4322520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43231da177e4SLinus Torvalds { 43241da177e4SLinus Torvalds int error; 4325bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 432659b0df21SEric Paris const unsigned char *old_name; 4327bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4328bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4329da1ce067SMiklos Szeredi bool new_is_dir = false; 4330da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 43311da177e4SLinus Torvalds 43329409e22aSMiklos Szeredi /* 43339409e22aSMiklos Szeredi * Check source == target. 43349409e22aSMiklos Szeredi * On overlayfs need to look at underlying inodes. 43359409e22aSMiklos Szeredi */ 43369409e22aSMiklos Szeredi if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) 43371da177e4SLinus Torvalds return 0; 43381da177e4SLinus Torvalds 43391da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43401da177e4SLinus Torvalds if (error) 43411da177e4SLinus Torvalds return error; 43421da177e4SLinus Torvalds 4343da1ce067SMiklos Szeredi if (!target) { 4344a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4345da1ce067SMiklos Szeredi } else { 4346da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4347da1ce067SMiklos Szeredi 4348da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43491da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4350da1ce067SMiklos Szeredi else 4351da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4352da1ce067SMiklos Szeredi } 43531da177e4SLinus Torvalds if (error) 43541da177e4SLinus Torvalds return error; 43551da177e4SLinus Torvalds 43567177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 43571da177e4SLinus Torvalds return -EPERM; 43581da177e4SLinus Torvalds 4359520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4360520c8b16SMiklos Szeredi return -EINVAL; 4361520c8b16SMiklos Szeredi 4362bc27027aSMiklos Szeredi /* 4363bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4364bc27027aSMiklos Szeredi * we'll need to flip '..'. 4365bc27027aSMiklos Szeredi */ 4366da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4367da1ce067SMiklos Szeredi if (is_dir) { 4368bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4369bc27027aSMiklos Szeredi if (error) 4370bc27027aSMiklos Szeredi return error; 4371bc27027aSMiklos Szeredi } 4372da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4373da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4374da1ce067SMiklos Szeredi if (error) 4375da1ce067SMiklos Szeredi return error; 4376da1ce067SMiklos Szeredi } 4377da1ce067SMiklos Szeredi } 43780eeca283SRobert Love 43790b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43800b3974ebSMiklos Szeredi flags); 4381bc27027aSMiklos Szeredi if (error) 4382bc27027aSMiklos Szeredi return error; 4383bc27027aSMiklos Szeredi 4384bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4385bc27027aSMiklos Szeredi dget(new_dentry); 4386da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4387bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4388bc27027aSMiklos Szeredi else if (target) 43895955102cSAl Viro inode_lock(target); 4390bc27027aSMiklos Szeredi 4391bc27027aSMiklos Szeredi error = -EBUSY; 43927af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4393bc27027aSMiklos Szeredi goto out; 4394bc27027aSMiklos Szeredi 4395da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4396bc27027aSMiklos Szeredi error = -EMLINK; 4397da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4398bc27027aSMiklos Szeredi goto out; 4399da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4400da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4401da1ce067SMiklos Szeredi goto out; 4402da1ce067SMiklos Szeredi } 4403da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4404bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4405da1ce067SMiklos Szeredi if (!is_dir) { 4406bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4407bc27027aSMiklos Szeredi if (error) 4408bc27027aSMiklos Szeredi goto out; 4409da1ce067SMiklos Szeredi } 4410da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4411bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4412bc27027aSMiklos Szeredi if (error) 4413bc27027aSMiklos Szeredi goto out; 4414bc27027aSMiklos Szeredi } 44157177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4416520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4417520c8b16SMiklos Szeredi new_dir, new_dentry); 4418520c8b16SMiklos Szeredi } else { 44197177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4420520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4421520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4422520c8b16SMiklos Szeredi } 4423bc27027aSMiklos Szeredi if (error) 4424bc27027aSMiklos Szeredi goto out; 4425bc27027aSMiklos Szeredi 4426da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44271da177e4SLinus Torvalds if (is_dir) 4428bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4429bc27027aSMiklos Szeredi dont_mount(new_dentry); 44308ed936b5SEric W. Biederman detach_mounts(new_dentry); 4431bc27027aSMiklos Szeredi } 4432da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4433da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4434bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4435da1ce067SMiklos Szeredi else 4436da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4437da1ce067SMiklos Szeredi } 4438bc27027aSMiklos Szeredi out: 4439da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4440bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4441bc27027aSMiklos Szeredi else if (target) 44425955102cSAl Viro inode_unlock(target); 4443bc27027aSMiklos Szeredi dput(new_dentry); 4444da1ce067SMiklos Szeredi if (!error) { 4445123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4446da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4447da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4448da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4449da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4450da1ce067SMiklos Szeredi } 4451da1ce067SMiklos Szeredi } 44520eeca283SRobert Love fsnotify_oldname_free(old_name); 44530eeca283SRobert Love 44541da177e4SLinus Torvalds return error; 44551da177e4SLinus Torvalds } 44564d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44571da177e4SLinus Torvalds 4458520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4459520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44601da177e4SLinus Torvalds { 44611da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44621da177e4SLinus Torvalds struct dentry *trap; 4463f5beed75SAl Viro struct path old_path, new_path; 4464f5beed75SAl Viro struct qstr old_last, new_last; 4465f5beed75SAl Viro int old_type, new_type; 44668e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 446791a27b2aSJeff Layton struct filename *from; 446891a27b2aSJeff Layton struct filename *to; 4469f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4470c6a94284SJeff Layton bool should_retry = false; 44712ad94ae6SAl Viro int error; 4472520c8b16SMiklos Szeredi 44730d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4474da1ce067SMiklos Szeredi return -EINVAL; 4475da1ce067SMiklos Szeredi 44760d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44770d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4478520c8b16SMiklos Szeredi return -EINVAL; 4479520c8b16SMiklos Szeredi 44800d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44810d7a8555SMiklos Szeredi return -EPERM; 44820d7a8555SMiklos Szeredi 4483f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4484f5beed75SAl Viro target_flags = 0; 4485f5beed75SAl Viro 4486c6a94284SJeff Layton retry: 4487f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4488f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 448991a27b2aSJeff Layton if (IS_ERR(from)) { 449091a27b2aSJeff Layton error = PTR_ERR(from); 44911da177e4SLinus Torvalds goto exit; 449291a27b2aSJeff Layton } 44931da177e4SLinus Torvalds 4494f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4495f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 449691a27b2aSJeff Layton if (IS_ERR(to)) { 449791a27b2aSJeff Layton error = PTR_ERR(to); 44981da177e4SLinus Torvalds goto exit1; 449991a27b2aSJeff Layton } 45001da177e4SLinus Torvalds 45011da177e4SLinus Torvalds error = -EXDEV; 4502f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45031da177e4SLinus Torvalds goto exit2; 45041da177e4SLinus Torvalds 45051da177e4SLinus Torvalds error = -EBUSY; 4506f5beed75SAl Viro if (old_type != LAST_NORM) 45071da177e4SLinus Torvalds goto exit2; 45081da177e4SLinus Torvalds 45090a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45100a7c3937SMiklos Szeredi error = -EEXIST; 4511f5beed75SAl Viro if (new_type != LAST_NORM) 45121da177e4SLinus Torvalds goto exit2; 45131da177e4SLinus Torvalds 4514f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4515c30dabfeSJan Kara if (error) 4516c30dabfeSJan Kara goto exit2; 4517c30dabfeSJan Kara 45188e6d782cSJ. Bruce Fields retry_deleg: 4519f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45201da177e4SLinus Torvalds 4521f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45221da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45231da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45241da177e4SLinus Torvalds goto exit3; 45251da177e4SLinus Torvalds /* source must exist */ 45261da177e4SLinus Torvalds error = -ENOENT; 4527b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45281da177e4SLinus Torvalds goto exit4; 4529f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45301da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45311da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45321da177e4SLinus Torvalds goto exit4; 45330a7c3937SMiklos Szeredi error = -EEXIST; 45340a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45350a7c3937SMiklos Szeredi goto exit5; 4536da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4537da1ce067SMiklos Szeredi error = -ENOENT; 4538da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4539da1ce067SMiklos Szeredi goto exit5; 4540da1ce067SMiklos Szeredi 4541da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4542da1ce067SMiklos Szeredi error = -ENOTDIR; 4543f5beed75SAl Viro if (new_last.name[new_last.len]) 4544da1ce067SMiklos Szeredi goto exit5; 4545da1ce067SMiklos Szeredi } 4546da1ce067SMiklos Szeredi } 45470a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45480a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45490a7c3937SMiklos Szeredi error = -ENOTDIR; 4550f5beed75SAl Viro if (old_last.name[old_last.len]) 45510a7c3937SMiklos Szeredi goto exit5; 4552f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45530a7c3937SMiklos Szeredi goto exit5; 45540a7c3937SMiklos Szeredi } 45550a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45560a7c3937SMiklos Szeredi error = -EINVAL; 45570a7c3937SMiklos Szeredi if (old_dentry == trap) 45580a7c3937SMiklos Szeredi goto exit5; 45591da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4560da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45611da177e4SLinus Torvalds error = -ENOTEMPTY; 45621da177e4SLinus Torvalds if (new_dentry == trap) 45631da177e4SLinus Torvalds goto exit5; 45641da177e4SLinus Torvalds 4565f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4566f5beed75SAl Viro &new_path, new_dentry, flags); 4567be6d3e56SKentaro Takeda if (error) 4568c30dabfeSJan Kara goto exit5; 4569f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4570f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4571520c8b16SMiklos Szeredi &delegated_inode, flags); 45721da177e4SLinus Torvalds exit5: 45731da177e4SLinus Torvalds dput(new_dentry); 45741da177e4SLinus Torvalds exit4: 45751da177e4SLinus Torvalds dput(old_dentry); 45761da177e4SLinus Torvalds exit3: 4577f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45788e6d782cSJ. Bruce Fields if (delegated_inode) { 45798e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45808e6d782cSJ. Bruce Fields if (!error) 45818e6d782cSJ. Bruce Fields goto retry_deleg; 45828e6d782cSJ. Bruce Fields } 4583f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45841da177e4SLinus Torvalds exit2: 4585c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4586c6a94284SJeff Layton should_retry = true; 4587f5beed75SAl Viro path_put(&new_path); 45882ad94ae6SAl Viro putname(to); 45891da177e4SLinus Torvalds exit1: 4590f5beed75SAl Viro path_put(&old_path); 45911da177e4SLinus Torvalds putname(from); 4592c6a94284SJeff Layton if (should_retry) { 4593c6a94284SJeff Layton should_retry = false; 4594c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4595c6a94284SJeff Layton goto retry; 4596c6a94284SJeff Layton } 45972ad94ae6SAl Viro exit: 45981da177e4SLinus Torvalds return error; 45991da177e4SLinus Torvalds } 46001da177e4SLinus Torvalds 4601520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4602520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4603520c8b16SMiklos Szeredi { 4604520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4605520c8b16SMiklos Szeredi } 4606520c8b16SMiklos Szeredi 4607a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46085590ff0dSUlrich Drepper { 4609520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46105590ff0dSUlrich Drepper } 46115590ff0dSUlrich Drepper 4612787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4613787fb6bcSMiklos Szeredi { 4614787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4615787fb6bcSMiklos Szeredi if (error) 4616787fb6bcSMiklos Szeredi return error; 4617787fb6bcSMiklos Szeredi 4618787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4619787fb6bcSMiklos Szeredi return -EPERM; 4620787fb6bcSMiklos Szeredi 4621787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4622787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4623787fb6bcSMiklos Szeredi } 4624787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4625787fb6bcSMiklos Szeredi 46265d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46271da177e4SLinus Torvalds { 46285d826c84SAl Viro int len = PTR_ERR(link); 46291da177e4SLinus Torvalds if (IS_ERR(link)) 46301da177e4SLinus Torvalds goto out; 46311da177e4SLinus Torvalds 46321da177e4SLinus Torvalds len = strlen(link); 46331da177e4SLinus Torvalds if (len > (unsigned) buflen) 46341da177e4SLinus Torvalds len = buflen; 46351da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46361da177e4SLinus Torvalds len = -EFAULT; 46371da177e4SLinus Torvalds out: 46381da177e4SLinus Torvalds return len; 46391da177e4SLinus Torvalds } 46405d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 46411da177e4SLinus Torvalds 46421da177e4SLinus Torvalds /* 46431da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46446b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46456b255391SAl Viro * for any given inode is up to filesystem. 46461da177e4SLinus Torvalds */ 46471da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 46481da177e4SLinus Torvalds { 4649fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46505f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46515f2c4179SAl Viro const char *link = inode->i_link; 4652694a1764SMarcin Slusarz int res; 4653cc314eefSLinus Torvalds 4654d4dee48bSAl Viro if (!link) { 4655fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4656680baacbSAl Viro if (IS_ERR(link)) 4657680baacbSAl Viro return PTR_ERR(link); 4658d4dee48bSAl Viro } 4659680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4660fceef393SAl Viro do_delayed_call(&done); 4661694a1764SMarcin Slusarz return res; 46621da177e4SLinus Torvalds } 46634d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 46641da177e4SLinus Torvalds 46651da177e4SLinus Torvalds /* get the link contents into pagecache */ 46666b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4667fceef393SAl Viro struct delayed_call *callback) 46681da177e4SLinus Torvalds { 4669ebd09abbSDuane Griffin char *kaddr; 46701da177e4SLinus Torvalds struct page *page; 46716b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46726b255391SAl Viro 4673d3883d4fSAl Viro if (!dentry) { 4674d3883d4fSAl Viro page = find_get_page(mapping, 0); 4675d3883d4fSAl Viro if (!page) 46766b255391SAl Viro return ERR_PTR(-ECHILD); 4677d3883d4fSAl Viro if (!PageUptodate(page)) { 4678d3883d4fSAl Viro put_page(page); 4679d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4680d3883d4fSAl Viro } 4681d3883d4fSAl Viro } else { 4682090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46831da177e4SLinus Torvalds if (IS_ERR(page)) 46846fe6900eSNick Piggin return (char*)page; 4685d3883d4fSAl Viro } 4686fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 468721fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 468821fc61c7SAl Viro kaddr = page_address(page); 46896b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4690ebd09abbSDuane Griffin return kaddr; 46911da177e4SLinus Torvalds } 46921da177e4SLinus Torvalds 46936b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46941da177e4SLinus Torvalds 4695fceef393SAl Viro void page_put_link(void *arg) 46961da177e4SLinus Torvalds { 4697fceef393SAl Viro put_page(arg); 46981da177e4SLinus Torvalds } 46994d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47001da177e4SLinus Torvalds 4701aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4702aa80deabSAl Viro { 4703fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47046b255391SAl Viro int res = readlink_copy(buffer, buflen, 47056b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4706fceef393SAl Viro &done)); 4707fceef393SAl Viro do_delayed_call(&done); 4708aa80deabSAl Viro return res; 4709aa80deabSAl Viro } 4710aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4711aa80deabSAl Viro 471254566b2cSNick Piggin /* 471354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 471454566b2cSNick Piggin */ 471554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47161da177e4SLinus Torvalds { 47171da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47180adb25d2SKirill Korotaev struct page *page; 4719afddba49SNick Piggin void *fsdata; 4720beb497abSDmitriy Monakhov int err; 472154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 472254566b2cSNick Piggin if (nofs) 472354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47241da177e4SLinus Torvalds 47257e53cac4SNeilBrown retry: 4726afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 472754566b2cSNick Piggin flags, &page, &fsdata); 47281da177e4SLinus Torvalds if (err) 4729afddba49SNick Piggin goto fail; 4730afddba49SNick Piggin 473121fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4732afddba49SNick Piggin 4733afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4734afddba49SNick Piggin page, fsdata); 47351da177e4SLinus Torvalds if (err < 0) 47361da177e4SLinus Torvalds goto fail; 4737afddba49SNick Piggin if (err < len-1) 4738afddba49SNick Piggin goto retry; 4739afddba49SNick Piggin 47401da177e4SLinus Torvalds mark_inode_dirty(inode); 47411da177e4SLinus Torvalds return 0; 47421da177e4SLinus Torvalds fail: 47431da177e4SLinus Torvalds return err; 47441da177e4SLinus Torvalds } 47454d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47461da177e4SLinus Torvalds 47470adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47480adb25d2SKirill Korotaev { 47490adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4750c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47510adb25d2SKirill Korotaev } 47524d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47530adb25d2SKirill Korotaev 475492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47551da177e4SLinus Torvalds .readlink = generic_readlink, 47566b255391SAl Viro .get_link = page_get_link, 47571da177e4SLinus Torvalds }; 47581da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4759