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... */ 269b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 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 { 160794bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16081936386eSAl Viro struct inode *inode = dir->d_inode; 1609d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16101936386eSAl Viro 16119902af79SAl Viro inode_lock_shared(inode); 16121936386eSAl Viro /* Don't go there if it's already dead */ 161394bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 161494bdd655SAl Viro goto out; 161594bdd655SAl Viro again: 1616d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 161794bdd655SAl Viro if (IS_ERR(dentry)) 161894bdd655SAl Viro goto out; 161994bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1620949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1621949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1622949a852eSAl Viro int error = d_revalidate(dentry, flags); 1623949a852eSAl Viro if (unlikely(error <= 0)) { 162494bdd655SAl Viro if (!error) { 1625949a852eSAl Viro d_invalidate(dentry); 1626949a852eSAl Viro dput(dentry); 162794bdd655SAl Viro goto again; 162894bdd655SAl Viro } 162994bdd655SAl Viro dput(dentry); 1630949a852eSAl Viro dentry = ERR_PTR(error); 1631949a852eSAl Viro } 1632949a852eSAl Viro } 163394bdd655SAl Viro } else { 16341936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 163585c7f810SAl Viro d_lookup_done(dentry); 16361936386eSAl Viro if (unlikely(old)) { 16371936386eSAl Viro dput(dentry); 16381936386eSAl Viro dentry = old; 1639949a852eSAl Viro } 1640949a852eSAl Viro } 164194bdd655SAl Viro out: 16429902af79SAl Viro inode_unlock_shared(inode); 1643e3c13928SAl Viro return dentry; 16441da177e4SLinus Torvalds } 16451da177e4SLinus Torvalds 164652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164752094c8aSAl Viro { 164852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16494ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 165052094c8aSAl Viro if (err != -ECHILD) 165152094c8aSAl Viro return err; 16526e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 165352094c8aSAl Viro return -ECHILD; 165452094c8aSAl Viro } 16554ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165652094c8aSAl Viro } 165752094c8aSAl Viro 16589856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16599856fa1bSAl Viro { 16609856fa1bSAl Viro if (type == LAST_DOTDOT) { 16619e6697e2SAl Viro if (!nd->root.mnt) 16629e6697e2SAl Viro set_root(nd); 16639856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 166470291aecSAl Viro return follow_dotdot_rcu(nd); 16659856fa1bSAl Viro } else 1666397d425dSEric W. Biederman return follow_dotdot(nd); 16679856fa1bSAl Viro } 16689856fa1bSAl Viro return 0; 16699856fa1bSAl Viro } 16709856fa1bSAl Viro 1671181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1672181548c0SAl Viro struct inode *inode, unsigned seq) 1673d63ff28fSAl Viro { 1674626de996SAl Viro int error; 16751cf2665bSAl Viro struct saved *last; 1676756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1677626de996SAl Viro path_to_nameidata(link, nd); 1678626de996SAl Viro return -ELOOP; 1679626de996SAl Viro } 1680bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1681cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1682cd179f44SAl Viro mntget(link->mnt); 16837973387aSAl Viro } 1684626de996SAl Viro error = nd_alloc_stack(nd); 1685626de996SAl Viro if (unlikely(error)) { 1686bc40aee0SAl Viro if (error == -ECHILD) { 1687bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1688bc40aee0SAl Viro return -ECHILD; 1689bc40aee0SAl Viro error = nd_alloc_stack(nd); 1690bc40aee0SAl Viro } 1691bc40aee0SAl Viro if (error) { 1692cd179f44SAl Viro path_put(link); 1693626de996SAl Viro return error; 1694626de996SAl Viro } 1695bc40aee0SAl Viro } 1696626de996SAl Viro 1697ab104923SAl Viro last = nd->stack + nd->depth++; 16981cf2665bSAl Viro last->link = *link; 1699fceef393SAl Viro clear_delayed_call(&last->done); 1700fceef393SAl Viro nd->link_inode = inode; 17010450b2d1SAl Viro last->seq = seq; 1702d63ff28fSAl Viro return 1; 1703d63ff28fSAl Viro } 1704d63ff28fSAl Viro 17053ddcd056SLinus Torvalds /* 17063ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17073ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17083ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17093ddcd056SLinus Torvalds * for the common case. 17103ddcd056SLinus Torvalds */ 1711254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1712181548c0SAl Viro int follow, 1713181548c0SAl Viro struct inode *inode, unsigned seq) 17143ddcd056SLinus Torvalds { 1715d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1716d63ff28fSAl Viro return 0; 1717d63ff28fSAl Viro if (!follow) 1718d63ff28fSAl Viro return 0; 1719a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1720a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1721a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1722a7f77542SAl Viro return -ECHILD; 1723a7f77542SAl Viro } 1724181548c0SAl Viro return pick_link(nd, link, inode, seq); 17253ddcd056SLinus Torvalds } 17263ddcd056SLinus Torvalds 17274693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17284693a547SAl Viro 17294693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1730ce57dfc1SAl Viro { 1731caa85634SAl Viro struct path path; 1732ce57dfc1SAl Viro struct inode *inode; 1733254cf582SAl Viro unsigned seq; 1734ce57dfc1SAl Viro int err; 1735ce57dfc1SAl Viro /* 1736ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1737ce57dfc1SAl Viro * to be able to know about the current root directory and 1738ce57dfc1SAl Viro * parent relationships. 1739ce57dfc1SAl Viro */ 17404693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17414693a547SAl Viro err = handle_dots(nd, nd->last_type); 17424693a547SAl Viro if (flags & WALK_PUT) 17434693a547SAl Viro put_link(nd); 17444693a547SAl Viro return err; 17454693a547SAl Viro } 1746254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1747e9742b53SAl Viro if (unlikely(err <= 0)) { 1748697f514dSMiklos Szeredi if (err < 0) 1749f0a9ba70SAl Viro return err; 1750e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1751e3c13928SAl Viro nd->flags); 1752e3c13928SAl Viro if (IS_ERR(path.dentry)) 1753e3c13928SAl Viro return PTR_ERR(path.dentry); 17547500c38aSAl Viro 1755e3c13928SAl Viro path.mnt = nd->path.mnt; 1756e3c13928SAl Viro err = follow_managed(&path, nd); 1757e3c13928SAl Viro if (unlikely(err < 0)) 1758f0a9ba70SAl Viro return err; 1759697f514dSMiklos Szeredi 17607500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17617500c38aSAl Viro path_to_nameidata(&path, nd); 17627500c38aSAl Viro return -ENOENT; 17637500c38aSAl Viro } 17647500c38aSAl Viro 1765254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1766d4565649SAl Viro inode = d_backing_inode(path.dentry); 1767766c4cbfSAl Viro } 1768697f514dSMiklos Szeredi 17694693a547SAl Viro if (flags & WALK_PUT) 17704693a547SAl Viro put_link(nd); 1771181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1772d63ff28fSAl Viro if (unlikely(err)) 1773d63ff28fSAl Viro return err; 1774caa85634SAl Viro path_to_nameidata(&path, nd); 1775ce57dfc1SAl Viro nd->inode = inode; 1776254cf582SAl Viro nd->seq = seq; 1777ce57dfc1SAl Viro return 0; 1778ce57dfc1SAl Viro } 1779ce57dfc1SAl Viro 17801da177e4SLinus Torvalds /* 1781bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1782bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1783bfcfaa77SLinus Torvalds * 1784bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1785bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1786bfcfaa77SLinus Torvalds * fast. 1787bfcfaa77SLinus Torvalds * 1788bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1789bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1790bfcfaa77SLinus Torvalds * crossing operation. 1791bfcfaa77SLinus Torvalds * 1792bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1793bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1794bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1795bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1796bfcfaa77SLinus Torvalds */ 1797bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1798bfcfaa77SLinus Torvalds 1799f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1800bfcfaa77SLinus Torvalds 1801468a9428SGeorge Spelvin #ifdef HASH_MIX 1802bfcfaa77SLinus Torvalds 1803468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1804468a9428SGeorge Spelvin 1805468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18062a18da7aSGeorge Spelvin /* 18072a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18082a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18092a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18102a18da7aSGeorge Spelvin * and no temporaries. 18112a18da7aSGeorge Spelvin * 18122a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18132a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18142a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18152a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18162a18da7aSGeorge Spelvin * 18172a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18182a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18192a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18202a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18212a18da7aSGeorge Spelvin * 18222a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18232a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18242a18da7aSGeorge Spelvin * toggling any given output bit. 18252a18da7aSGeorge Spelvin * 18262a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18272a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18282a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18292a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18302a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18312a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18322a18da7aSGeorge Spelvin * Perfect: 8192 258048 18332a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18342a18da7aSGeorge Spelvin */ 18352a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18362a18da7aSGeorge Spelvin ( x ^= (a), \ 18372a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18382a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18392a18da7aSGeorge Spelvin y *= 9 ) 1840bfcfaa77SLinus Torvalds 18410fed3ac8SGeorge Spelvin /* 18422a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18432a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18442a18da7aSGeorge Spelvin * work done before the hash value is used. 18450fed3ac8SGeorge Spelvin */ 18462a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18470fed3ac8SGeorge Spelvin { 18482a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18492a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18502a18da7aSGeorge Spelvin return y >> 32; 18510fed3ac8SGeorge Spelvin } 18520fed3ac8SGeorge Spelvin 1853bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1854bfcfaa77SLinus Torvalds 18552a18da7aSGeorge Spelvin /* 18562a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18572a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18582a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18592a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18602a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18612a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18622a18da7aSGeorge Spelvin * Perfect: 2048 31744 18632a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18642a18da7aSGeorge Spelvin */ 18652a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18662a18da7aSGeorge Spelvin ( x ^= (a), \ 18672a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18682a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18692a18da7aSGeorge Spelvin y *= 9 ) 1870bfcfaa77SLinus Torvalds 18712a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18720fed3ac8SGeorge Spelvin { 18732a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18742a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18750fed3ac8SGeorge Spelvin } 18760fed3ac8SGeorge Spelvin 1877bfcfaa77SLinus Torvalds #endif 1878bfcfaa77SLinus Torvalds 18792a18da7aSGeorge Spelvin /* 18802a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18812a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18822a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18832a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18842a18da7aSGeorge Spelvin * finds the delimiter after the name. 18852a18da7aSGeorge Spelvin */ 1886fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 1887bfcfaa77SLinus Torvalds { 18882a18da7aSGeorge Spelvin unsigned long a, x = 0, y = 0; 1889bfcfaa77SLinus Torvalds 1890bfcfaa77SLinus Torvalds for (;;) { 1891fcfd2fbfSGeorge Spelvin if (!len) 1892fcfd2fbfSGeorge Spelvin goto done; 1893e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1894bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1895bfcfaa77SLinus Torvalds break; 18962a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1897bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1898bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1899bfcfaa77SLinus Torvalds } 19002a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1901bfcfaa77SLinus Torvalds done: 19022a18da7aSGeorge Spelvin return fold_hash(x, y); 1903bfcfaa77SLinus Torvalds } 1904bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1905bfcfaa77SLinus Torvalds 1906fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1907fcfd2fbfSGeorge Spelvin u64 hashlen_string(const char *name) 1908fcfd2fbfSGeorge Spelvin { 19092a18da7aSGeorge Spelvin unsigned long a = 0, x = 0, y = 0, adata, mask, len; 1910fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1911fcfd2fbfSGeorge Spelvin 1912fcfd2fbfSGeorge Spelvin len = -sizeof(unsigned long); 1913fcfd2fbfSGeorge Spelvin do { 19142a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1915fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 1916fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1917fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1918fcfd2fbfSGeorge Spelvin 1919fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1920fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19212a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1922fcfd2fbfSGeorge Spelvin 19232a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1924fcfd2fbfSGeorge Spelvin } 1925fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1926fcfd2fbfSGeorge Spelvin 1927bfcfaa77SLinus Torvalds /* 1928bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1929d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1930bfcfaa77SLinus Torvalds */ 1931d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1932bfcfaa77SLinus Torvalds { 19332a18da7aSGeorge Spelvin unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len; 193436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1935bfcfaa77SLinus Torvalds 1936bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1937bfcfaa77SLinus Torvalds do { 19382a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1939bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1940e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 194136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 194236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1943bfcfaa77SLinus Torvalds 194436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 194536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 194636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19472a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 194836126f8fSLinus Torvalds 19492a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1950bfcfaa77SLinus Torvalds } 1951bfcfaa77SLinus Torvalds 19522a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1953bfcfaa77SLinus Torvalds 1954fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 1955fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 19560145acc2SLinus Torvalds { 19570145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 19580145acc2SLinus Torvalds while (len--) 1959fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19600145acc2SLinus Torvalds return end_name_hash(hash); 19610145acc2SLinus Torvalds } 1962ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19630145acc2SLinus Torvalds 1964fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1965f2a031b6SGeorge Spelvin u64 hashlen_string(const char *name) 1966fcfd2fbfSGeorge Spelvin { 1967fcfd2fbfSGeorge Spelvin unsigned long hash = init_name_hash(); 1968fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1969fcfd2fbfSGeorge Spelvin 1970fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1971e0ab7af9SGeorge Spelvin while (c) { 1972fcfd2fbfSGeorge Spelvin len++; 1973fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1974fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1975e0ab7af9SGeorge Spelvin } 1976fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1977fcfd2fbfSGeorge Spelvin } 1978f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1979fcfd2fbfSGeorge Spelvin 19803ddcd056SLinus Torvalds /* 1981200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1982200e9ef7SLinus Torvalds * one character. 1983200e9ef7SLinus Torvalds */ 1984d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1985200e9ef7SLinus Torvalds { 1986200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1987200e9ef7SLinus Torvalds unsigned long len = 0, c; 1988200e9ef7SLinus Torvalds 1989200e9ef7SLinus Torvalds c = (unsigned char)*name; 1990200e9ef7SLinus Torvalds do { 1991200e9ef7SLinus Torvalds len++; 1992200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1993200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1994200e9ef7SLinus Torvalds } while (c && c != '/'); 1995d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1996200e9ef7SLinus Torvalds } 1997200e9ef7SLinus Torvalds 1998bfcfaa77SLinus Torvalds #endif 1999bfcfaa77SLinus Torvalds 2000200e9ef7SLinus Torvalds /* 20011da177e4SLinus Torvalds * Name resolution. 2002ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2003ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20041da177e4SLinus Torvalds * 2005ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2006ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20071da177e4SLinus Torvalds */ 20086de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20091da177e4SLinus Torvalds { 20101da177e4SLinus Torvalds int err; 20111da177e4SLinus Torvalds 20121da177e4SLinus Torvalds while (*name=='/') 20131da177e4SLinus Torvalds name++; 20141da177e4SLinus Torvalds if (!*name) 20159e18f10aSAl Viro return 0; 20161da177e4SLinus Torvalds 20171da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20181da177e4SLinus Torvalds for(;;) { 2019d6bb3e90SLinus Torvalds u64 hash_len; 2020fe479a58SAl Viro int type; 20211da177e4SLinus Torvalds 202252094c8aSAl Viro err = may_lookup(nd); 20231da177e4SLinus Torvalds if (err) 20243595e234SAl Viro return err; 20251da177e4SLinus Torvalds 2026d6bb3e90SLinus Torvalds hash_len = hash_name(name); 20271da177e4SLinus Torvalds 2028fe479a58SAl Viro type = LAST_NORM; 2029d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2030fe479a58SAl Viro case 2: 2031200e9ef7SLinus Torvalds if (name[1] == '.') { 2032fe479a58SAl Viro type = LAST_DOTDOT; 203316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 203416c2cd71SAl Viro } 2035fe479a58SAl Viro break; 2036fe479a58SAl Viro case 1: 2037fe479a58SAl Viro type = LAST_DOT; 2038fe479a58SAl Viro } 20395a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20405a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 204116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20425a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2043a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2044da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20455a202bcdSAl Viro if (err < 0) 20463595e234SAl Viro return err; 2047d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2048d6bb3e90SLinus Torvalds name = this.name; 20495a202bcdSAl Viro } 20505a202bcdSAl Viro } 2051fe479a58SAl Viro 2052d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2053d6bb3e90SLinus Torvalds nd->last.name = name; 20545f4a6a69SAl Viro nd->last_type = type; 20555f4a6a69SAl Viro 2056d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2057d6bb3e90SLinus Torvalds if (!*name) 2058bdf6cbf1SAl Viro goto OK; 2059200e9ef7SLinus Torvalds /* 2060200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2061200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2062200e9ef7SLinus Torvalds */ 2063200e9ef7SLinus Torvalds do { 2064d6bb3e90SLinus Torvalds name++; 2065d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20668620c238SAl Viro if (unlikely(!*name)) { 20678620c238SAl Viro OK: 2068368ee9baSAl Viro /* pathname body, done */ 20698620c238SAl Viro if (!nd->depth) 20708620c238SAl Viro return 0; 20718620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2072368ee9baSAl Viro /* trailing symlink, done */ 20738620c238SAl Viro if (!name) 20748620c238SAl Viro return 0; 20758620c238SAl Viro /* last component of nested symlink */ 20764693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 20778620c238SAl Viro } else { 20784693a547SAl Viro err = walk_component(nd, WALK_GET); 20798620c238SAl Viro } 2080ce57dfc1SAl Viro if (err < 0) 20813595e234SAl Viro return err; 2082fe479a58SAl Viro 2083ce57dfc1SAl Viro if (err) { 2084626de996SAl Viro const char *s = get_link(nd); 20855a460275SAl Viro 2086a1c83681SViresh Kumar if (IS_ERR(s)) 20873595e234SAl Viro return PTR_ERR(s); 2088172a39a0SAl Viro err = 0; 208912b09578SAl Viro if (unlikely(!s)) { 209012b09578SAl Viro /* jumped */ 2091b9ff4429SAl Viro put_link(nd); 209212b09578SAl Viro } else { 2093071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 209432cd7468SAl Viro name = s; 20959e18f10aSAl Viro continue; 209648c8b0c5SAl Viro } 209731e6b01fSNick Piggin } 209897242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 209997242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 210097242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 210197242f99SAl Viro return -ECHILD; 210297242f99SAl Viro } 21033595e234SAl Viro return -ENOTDIR; 21045f4a6a69SAl Viro } 2105ce57dfc1SAl Viro } 210697242f99SAl Viro } 21071da177e4SLinus Torvalds 2108c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 210931e6b01fSNick Piggin { 211031e6b01fSNick Piggin int retval = 0; 2111c8a53ee5SAl Viro const char *s = nd->name->name; 211231e6b01fSNick Piggin 211331e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2114980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 211531e6b01fSNick Piggin nd->depth = 0; 21165b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2117b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2118b18825a7SDavid Howells struct inode *inode = root->d_inode; 2119fd2f7cb5SAl Viro if (*s) { 212044b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2121368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21225b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21235b6ca027SAl Viro if (retval) 2124368ee9baSAl Viro return ERR_PTR(retval); 212573d049a4SAl Viro } 21265b6ca027SAl Viro nd->path = nd->root; 21275b6ca027SAl Viro nd->inode = inode; 21285b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21298b61e74fSAl Viro rcu_read_lock(); 21305b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21318f47a016SAl Viro nd->root_seq = nd->seq; 213248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21335b6ca027SAl Viro } else { 21345b6ca027SAl Viro path_get(&nd->path); 21355b6ca027SAl Viro } 2136368ee9baSAl Viro return s; 21375b6ca027SAl Viro } 21385b6ca027SAl Viro 213931e6b01fSNick Piggin nd->root.mnt = NULL; 2140248fb5b9SAl Viro nd->path.mnt = NULL; 2141248fb5b9SAl Viro nd->path.dentry = NULL; 214231e6b01fSNick Piggin 214348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2144fd2f7cb5SAl Viro if (*s == '/') { 21459e6697e2SAl Viro if (flags & LOOKUP_RCU) 21468b61e74fSAl Viro rcu_read_lock(); 2147e41f7d4eSAl Viro set_root(nd); 2148248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2149ef55d917SAl Viro return s; 2150ef55d917SAl Viro nd->root.mnt = NULL; 2151ef55d917SAl Viro rcu_read_unlock(); 2152ef55d917SAl Viro return ERR_PTR(-ECHILD); 2153c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2154e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 215531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2156c28cc364SNick Piggin unsigned seq; 215731e6b01fSNick Piggin 21588b61e74fSAl Viro rcu_read_lock(); 215931e6b01fSNick Piggin 2160c28cc364SNick Piggin do { 2161c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 216231e6b01fSNick Piggin nd->path = fs->pwd; 2163ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2164c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2165c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2166e41f7d4eSAl Viro } else { 2167e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2168ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2169e41f7d4eSAl Viro } 2170ef55d917SAl Viro return s; 217131e6b01fSNick Piggin } else { 2172582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2173c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 217431e6b01fSNick Piggin struct dentry *dentry; 217531e6b01fSNick Piggin 21762903ff01SAl Viro if (!f.file) 2177368ee9baSAl Viro return ERR_PTR(-EBADF); 217831e6b01fSNick Piggin 21792903ff01SAl Viro dentry = f.file->f_path.dentry; 218031e6b01fSNick Piggin 2181fd2f7cb5SAl Viro if (*s) { 218244b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21832903ff01SAl Viro fdput(f); 2184368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2185f52e0c11SAl Viro } 21862903ff01SAl Viro } 21872903ff01SAl Viro 21882903ff01SAl Viro nd->path = f.file->f_path; 2189e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 21908b61e74fSAl Viro rcu_read_lock(); 219134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 219234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 21935590ff0dSUlrich Drepper } else { 21942903ff01SAl Viro path_get(&nd->path); 219534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 21961da177e4SLinus Torvalds } 219734a26b99SAl Viro fdput(f); 2198368ee9baSAl Viro return s; 2199e41f7d4eSAl Viro } 22009b4a9b14SAl Viro } 22019b4a9b14SAl Viro 22023bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 220395fa25d9SAl Viro { 220495fa25d9SAl Viro const char *s; 2205fec2fa24SAl Viro int error = may_follow_link(nd); 2206deb106c6SAl Viro if (unlikely(error)) 22073bdba28bSAl Viro return ERR_PTR(error); 220895fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2209fab51e8aSAl Viro nd->stack[0].name = NULL; 22103b2e7f75SAl Viro s = get_link(nd); 2211deb106c6SAl Viro return s ? s : ""; 221295fa25d9SAl Viro } 221395fa25d9SAl Viro 2214caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2215bd92d7feSAl Viro { 2216bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2217bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2218bd92d7feSAl Viro 2219bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2220deb106c6SAl Viro return walk_component(nd, 22214693a547SAl Viro nd->flags & LOOKUP_FOLLOW 22224693a547SAl Viro ? nd->depth 22234693a547SAl Viro ? WALK_PUT | WALK_GET 22244693a547SAl Viro : WALK_GET 22254693a547SAl Viro : 0); 2226bd92d7feSAl Viro } 2227bd92d7feSAl Viro 22289b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2229c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22309b4a9b14SAl Viro { 2231c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2232bd92d7feSAl Viro int err; 223331e6b01fSNick Piggin 2234368ee9baSAl Viro if (IS_ERR(s)) 2235368ee9baSAl Viro return PTR_ERR(s); 22363bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22373bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22383bdba28bSAl Viro s = trailing_symlink(nd); 22393bdba28bSAl Viro if (IS_ERR(s)) { 22403bdba28bSAl Viro err = PTR_ERR(s); 22416d7b5aaeSAl Viro break; 2242bd92d7feSAl Viro } 2243bd92d7feSAl Viro } 22449f1fafeeSAl Viro if (!err) 22459f1fafeeSAl Viro err = complete_walk(nd); 2246bd92d7feSAl Viro 2247deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2248deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2249bd23a539SAl Viro err = -ENOTDIR; 2250625b6d10SAl Viro if (!err) { 2251625b6d10SAl Viro *path = nd->path; 2252625b6d10SAl Viro nd->path.mnt = NULL; 2253625b6d10SAl Viro nd->path.dentry = NULL; 2254625b6d10SAl Viro } 2255deb106c6SAl Viro terminate_walk(nd); 2256bd92d7feSAl Viro return err; 225731e6b01fSNick Piggin } 225831e6b01fSNick Piggin 2259625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22609ad1aaa6SAl Viro struct path *path, struct path *root) 2261873f1eedSJeff Layton { 2262894bc8c4SAl Viro int retval; 22639883d185SAl Viro struct nameidata nd; 2264abc9f5beSAl Viro if (IS_ERR(name)) 2265abc9f5beSAl Viro return PTR_ERR(name); 22669ad1aaa6SAl Viro if (unlikely(root)) { 22679ad1aaa6SAl Viro nd.root = *root; 22689ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22699ad1aaa6SAl Viro } 22709883d185SAl Viro set_nameidata(&nd, dfd, name); 2271c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2272873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2273c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2274873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2275c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2276873f1eedSJeff Layton 2277873f1eedSJeff Layton if (likely(!retval)) 2278625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 22799883d185SAl Viro restore_nameidata(); 2280e4bd1c1aSAl Viro putname(name); 2281873f1eedSJeff Layton return retval; 2282873f1eedSJeff Layton } 2283873f1eedSJeff Layton 22848bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2285c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2286391172c4SAl Viro struct path *parent) 22878bcb77faSAl Viro { 2288c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2289368ee9baSAl Viro int err; 2290368ee9baSAl Viro if (IS_ERR(s)) 2291368ee9baSAl Viro return PTR_ERR(s); 2292368ee9baSAl Viro err = link_path_walk(s, nd); 22938bcb77faSAl Viro if (!err) 22948bcb77faSAl Viro err = complete_walk(nd); 2295391172c4SAl Viro if (!err) { 2296391172c4SAl Viro *parent = nd->path; 2297391172c4SAl Viro nd->path.mnt = NULL; 2298391172c4SAl Viro nd->path.dentry = NULL; 2299391172c4SAl Viro } 2300deb106c6SAl Viro terminate_walk(nd); 23018bcb77faSAl Viro return err; 23028bcb77faSAl Viro } 23038bcb77faSAl Viro 23045c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2305391172c4SAl Viro unsigned int flags, struct path *parent, 2306391172c4SAl Viro struct qstr *last, int *type) 23078bcb77faSAl Viro { 23088bcb77faSAl Viro int retval; 23099883d185SAl Viro struct nameidata nd; 23108bcb77faSAl Viro 23115c31b6ceSAl Viro if (IS_ERR(name)) 23125c31b6ceSAl Viro return name; 23139883d185SAl Viro set_nameidata(&nd, dfd, name); 2314c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23158bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2316c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23178bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2318c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2319391172c4SAl Viro if (likely(!retval)) { 2320391172c4SAl Viro *last = nd.last; 2321391172c4SAl Viro *type = nd.last_type; 2322391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23235c31b6ceSAl Viro } else { 23245c31b6ceSAl Viro putname(name); 23255c31b6ceSAl Viro name = ERR_PTR(retval); 2326391172c4SAl Viro } 23279883d185SAl Viro restore_nameidata(); 23285c31b6ceSAl Viro return name; 23298bcb77faSAl Viro } 23308bcb77faSAl Viro 233179714f72SAl Viro /* does lookup, returns the object with parent locked */ 233279714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23335590ff0dSUlrich Drepper { 23345c31b6ceSAl Viro struct filename *filename; 23355c31b6ceSAl Viro struct dentry *d; 2336391172c4SAl Viro struct qstr last; 2337391172c4SAl Viro int type; 233851689104SPaul Moore 23395c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23405c31b6ceSAl Viro &last, &type); 234151689104SPaul Moore if (IS_ERR(filename)) 234251689104SPaul Moore return ERR_CAST(filename); 23435c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2344391172c4SAl Viro path_put(path); 23455c31b6ceSAl Viro putname(filename); 23465c31b6ceSAl Viro return ERR_PTR(-EINVAL); 234779714f72SAl Viro } 23485955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2349391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 235079714f72SAl Viro if (IS_ERR(d)) { 23515955102cSAl Viro inode_unlock(path->dentry->d_inode); 2352391172c4SAl Viro path_put(path); 235379714f72SAl Viro } 235451689104SPaul Moore putname(filename); 235579714f72SAl Viro return d; 23565590ff0dSUlrich Drepper } 23575590ff0dSUlrich Drepper 2358d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2359d1811465SAl Viro { 2360abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2361abc9f5beSAl Viro flags, path, NULL); 2362d1811465SAl Viro } 23634d359507SAl Viro EXPORT_SYMBOL(kern_path); 2364d1811465SAl Viro 236516f18200SJosef 'Jeff' Sipek /** 236616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 236716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 236816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 236916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 237016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2371e0a01249SAl Viro * @path: pointer to struct path to fill 237216f18200SJosef 'Jeff' Sipek */ 237316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 237416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2375e0a01249SAl Viro struct path *path) 237616f18200SJosef 'Jeff' Sipek { 23779ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 23789ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2379abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2380abc9f5beSAl Viro flags , path, &root); 238116f18200SJosef 'Jeff' Sipek } 23824d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 238316f18200SJosef 'Jeff' Sipek 2384eead1911SChristoph Hellwig /** 23853c9fe8cdSMiklos Szeredi * lookup_hash - lookup single pathname component on already hashed name 23863c9fe8cdSMiklos Szeredi * @name: name and hash to lookup 23873c9fe8cdSMiklos Szeredi * @base: base directory to lookup from 23883c9fe8cdSMiklos Szeredi * 23893c9fe8cdSMiklos Szeredi * The name must have been verified and hashed (see lookup_one_len()). Using 23903c9fe8cdSMiklos Szeredi * this after just full_name_hash() is unsafe. 23913c9fe8cdSMiklos Szeredi * 23923c9fe8cdSMiklos Szeredi * This function also doesn't check for search permission on base directory. 23933c9fe8cdSMiklos Szeredi * 23943c9fe8cdSMiklos Szeredi * Use lookup_one_len_unlocked() instead, unless you really know what you are 23953c9fe8cdSMiklos Szeredi * doing. 23963c9fe8cdSMiklos Szeredi * 23973c9fe8cdSMiklos Szeredi * Do not hold i_mutex; this helper takes i_mutex if necessary. 23983c9fe8cdSMiklos Szeredi */ 23993c9fe8cdSMiklos Szeredi struct dentry *lookup_hash(const struct qstr *name, struct dentry *base) 24003c9fe8cdSMiklos Szeredi { 24013c9fe8cdSMiklos Szeredi struct dentry *ret; 24023c9fe8cdSMiklos Szeredi 24033c9fe8cdSMiklos Szeredi ret = lookup_dcache(name, base, 0); 24043c9fe8cdSMiklos Szeredi if (!ret) 24053c9fe8cdSMiklos Szeredi ret = lookup_slow(name, base, 0); 24063c9fe8cdSMiklos Szeredi 24073c9fe8cdSMiklos Szeredi return ret; 24083c9fe8cdSMiklos Szeredi } 24093c9fe8cdSMiklos Szeredi EXPORT_SYMBOL(lookup_hash); 24103c9fe8cdSMiklos Szeredi 24113c9fe8cdSMiklos Szeredi /** 2412a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2413eead1911SChristoph Hellwig * @name: pathname component to lookup 2414eead1911SChristoph Hellwig * @base: base directory to lookup from 2415eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2416eead1911SChristoph Hellwig * 2417a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24189e7543e9SAl Viro * not be called by generic code. 2419bbddca8eSNeilBrown * 2420bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2421eead1911SChristoph Hellwig */ 2422057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2423057f6c01SJames Morris { 2424057f6c01SJames Morris struct qstr this; 24256a96ba54SAl Viro unsigned int c; 2426cda309deSMiklos Szeredi int err; 2427057f6c01SJames Morris 24285955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24292f9092e1SDavid Woodhouse 24306a96ba54SAl Viro this.name = name; 24316a96ba54SAl Viro this.len = len; 24320145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 24336a96ba54SAl Viro if (!len) 24346a96ba54SAl Viro return ERR_PTR(-EACCES); 24356a96ba54SAl Viro 243621d8a15aSAl Viro if (unlikely(name[0] == '.')) { 243721d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 243821d8a15aSAl Viro return ERR_PTR(-EACCES); 243921d8a15aSAl Viro } 244021d8a15aSAl Viro 24416a96ba54SAl Viro while (len--) { 24426a96ba54SAl Viro c = *(const unsigned char *)name++; 24436a96ba54SAl Viro if (c == '/' || c == '\0') 24446a96ba54SAl Viro return ERR_PTR(-EACCES); 24456a96ba54SAl Viro } 24465a202bcdSAl Viro /* 24475a202bcdSAl Viro * See if the low-level filesystem might want 24485a202bcdSAl Viro * to use its own hash.. 24495a202bcdSAl Viro */ 24505a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2451da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24525a202bcdSAl Viro if (err < 0) 24535a202bcdSAl Viro return ERR_PTR(err); 24545a202bcdSAl Viro } 2455eead1911SChristoph Hellwig 2456cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2457cda309deSMiklos Szeredi if (err) 2458cda309deSMiklos Szeredi return ERR_PTR(err); 2459cda309deSMiklos Szeredi 246072bd866aSAl Viro return __lookup_hash(&this, base, 0); 2461057f6c01SJames Morris } 24624d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2463057f6c01SJames Morris 2464bbddca8eSNeilBrown /** 2465bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2466bbddca8eSNeilBrown * @name: pathname component to lookup 2467bbddca8eSNeilBrown * @base: base directory to lookup from 2468bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2469bbddca8eSNeilBrown * 2470bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2471bbddca8eSNeilBrown * not be called by generic code. 2472bbddca8eSNeilBrown * 2473bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2474bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2475bbddca8eSNeilBrown */ 2476bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2477bbddca8eSNeilBrown struct dentry *base, int len) 2478bbddca8eSNeilBrown { 2479bbddca8eSNeilBrown struct qstr this; 2480bbddca8eSNeilBrown unsigned int c; 2481bbddca8eSNeilBrown int err; 2482bbddca8eSNeilBrown 2483bbddca8eSNeilBrown this.name = name; 2484bbddca8eSNeilBrown this.len = len; 2485bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2486bbddca8eSNeilBrown if (!len) 2487bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2488bbddca8eSNeilBrown 2489bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2490bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2491bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2492bbddca8eSNeilBrown } 2493bbddca8eSNeilBrown 2494bbddca8eSNeilBrown while (len--) { 2495bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2496bbddca8eSNeilBrown if (c == '/' || c == '\0') 2497bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2498bbddca8eSNeilBrown } 2499bbddca8eSNeilBrown /* 2500bbddca8eSNeilBrown * See if the low-level filesystem might want 2501bbddca8eSNeilBrown * to use its own hash.. 2502bbddca8eSNeilBrown */ 2503bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2504bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2505bbddca8eSNeilBrown if (err < 0) 2506bbddca8eSNeilBrown return ERR_PTR(err); 2507bbddca8eSNeilBrown } 2508bbddca8eSNeilBrown 2509bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2510bbddca8eSNeilBrown if (err) 2511bbddca8eSNeilBrown return ERR_PTR(err); 2512bbddca8eSNeilBrown 25133c9fe8cdSMiklos Szeredi return lookup_hash(&this, base); 2514bbddca8eSNeilBrown } 2515bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2516bbddca8eSNeilBrown 25171fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25181fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25191da177e4SLinus Torvalds { 2520abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2521abc9f5beSAl Viro flags, path, NULL); 25221da177e4SLinus Torvalds } 2523b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25241fa1e7f6SAndy Whitcroft 2525873f1eedSJeff Layton /* 2526873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2527873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2528873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2529873f1eedSJeff Layton * path-walking is complete. 2530873f1eedSJeff Layton */ 2531a2ec4a2dSAl Viro static inline struct filename * 2532f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2533f5beed75SAl Viro struct path *parent, 2534f5beed75SAl Viro struct qstr *last, 2535f5beed75SAl Viro int *type, 25369e790bd6SJeff Layton unsigned int flags) 25372ad94ae6SAl Viro { 25389e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 25395c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 25405c31b6ceSAl Viro parent, last, type); 25412ad94ae6SAl Viro } 25422ad94ae6SAl Viro 25438033426eSJeff Layton /** 2544197df04cSAl Viro * mountpoint_last - look up last component for umount 25458033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25468033426eSJeff Layton * @path: pointer to container for result 25478033426eSJeff Layton * 25488033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25498033426eSJeff Layton * need to resolve the path without doing any revalidation. 25508033426eSJeff Layton * 25518033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25528033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25538033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25548033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25558033426eSJeff Layton * bogus and it doesn't exist. 25568033426eSJeff Layton * 25578033426eSJeff Layton * Returns: 25588033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 25598033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 25608033426eSJeff Layton * put in this case. 25618033426eSJeff Layton * 25628033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 25638033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 25648033426eSJeff Layton * The nd->path reference will also be put. 25658033426eSJeff Layton * 25668033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 25678033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 25688033426eSJeff Layton * to the link, and nd->path will *not* be put. 25698033426eSJeff Layton */ 25708033426eSJeff Layton static int 2571197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 25728033426eSJeff Layton { 25738033426eSJeff Layton int error = 0; 25748033426eSJeff Layton struct dentry *dentry; 25758033426eSJeff Layton struct dentry *dir = nd->path.dentry; 25768033426eSJeff Layton 257735759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 257835759521SAl Viro if (nd->flags & LOOKUP_RCU) { 25796e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2580deb106c6SAl Viro return -ECHILD; 25818033426eSJeff Layton } 25828033426eSJeff Layton 25838033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 25848033426eSJeff Layton 25858033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 25868033426eSJeff Layton error = handle_dots(nd, nd->last_type); 258735759521SAl Viro if (error) 2588deb106c6SAl Viro return error; 25898033426eSJeff Layton dentry = dget(nd->path.dentry); 2590949a852eSAl Viro } else { 25918033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 25928033426eSJeff Layton if (!dentry) { 25938033426eSJeff Layton /* 2594949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2595949a852eSAl Viro * cache, so that means that this dentry is probably 2596949a852eSAl Viro * a symlink or the path doesn't actually point 2597949a852eSAl Viro * to a mounted dentry. 25988033426eSJeff Layton */ 2599949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2600949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2601949a852eSAl Viro if (IS_ERR(dentry)) 2602deb106c6SAl Viro return PTR_ERR(dentry); 26038033426eSJeff Layton } 2604bcceeebaSDave Jones } 2605698934dfSDavid Howells if (d_is_negative(dentry)) { 26068033426eSJeff Layton dput(dentry); 2607deb106c6SAl Viro return -ENOENT; 260835759521SAl Viro } 2609191d7f73SAl Viro if (nd->depth) 2610191d7f73SAl Viro put_link(nd); 26118033426eSJeff Layton path->dentry = dentry; 2612295dc39dSVasily Averin path->mnt = nd->path.mnt; 2613181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2614181548c0SAl Viro d_backing_inode(dentry), 0); 2615deb106c6SAl Viro if (unlikely(error)) 2616d63ff28fSAl Viro return error; 2617295dc39dSVasily Averin mntget(path->mnt); 26188033426eSJeff Layton follow_mount(path); 2619deb106c6SAl Viro return 0; 26208033426eSJeff Layton } 26218033426eSJeff Layton 26228033426eSJeff Layton /** 2623197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26242a78b857SMasanari Iida * @nd: lookup context 26258033426eSJeff Layton * @flags: lookup flags 2626c8a53ee5SAl Viro * @path: pointer to container for result 26278033426eSJeff Layton * 26288033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2629606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26308033426eSJeff Layton */ 26318033426eSJeff Layton static int 2632c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26338033426eSJeff Layton { 2634c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2635368ee9baSAl Viro int err; 2636368ee9baSAl Viro if (IS_ERR(s)) 2637368ee9baSAl Viro return PTR_ERR(s); 26383bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 26393bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 26403bdba28bSAl Viro s = trailing_symlink(nd); 26413bdba28bSAl Viro if (IS_ERR(s)) { 26423bdba28bSAl Viro err = PTR_ERR(s); 26438033426eSJeff Layton break; 26448033426eSJeff Layton } 26453bdba28bSAl Viro } 2646deb106c6SAl Viro terminate_walk(nd); 26478033426eSJeff Layton return err; 26488033426eSJeff Layton } 26498033426eSJeff Layton 26502d864651SAl Viro static int 2651668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26522d864651SAl Viro unsigned int flags) 26532d864651SAl Viro { 26549883d185SAl Viro struct nameidata nd; 2655cbaab2dbSAl Viro int error; 2656668696dcSAl Viro if (IS_ERR(name)) 2657668696dcSAl Viro return PTR_ERR(name); 26589883d185SAl Viro set_nameidata(&nd, dfd, name); 2659c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26602d864651SAl Viro if (unlikely(error == -ECHILD)) 2661c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26622d864651SAl Viro if (unlikely(error == -ESTALE)) 2663c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26642d864651SAl Viro if (likely(!error)) 2665668696dcSAl Viro audit_inode(name, path->dentry, 0); 26669883d185SAl Viro restore_nameidata(); 2667668696dcSAl Viro putname(name); 26682d864651SAl Viro return error; 26692d864651SAl Viro } 26702d864651SAl Viro 26718033426eSJeff Layton /** 2672197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26738033426eSJeff Layton * @dfd: directory file descriptor 26748033426eSJeff Layton * @name: pathname from userland 26758033426eSJeff Layton * @flags: lookup flags 26768033426eSJeff Layton * @path: pointer to container to hold result 26778033426eSJeff Layton * 26788033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26798033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26808033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26818033426eSJeff Layton * and avoid revalidating the last component. 26828033426eSJeff Layton * 26838033426eSJeff Layton * Returns 0 and populates "path" on success. 26848033426eSJeff Layton */ 26858033426eSJeff Layton int 2686197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26878033426eSJeff Layton struct path *path) 26888033426eSJeff Layton { 2689cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26908033426eSJeff Layton } 26918033426eSJeff Layton 26922d864651SAl Viro int 26932d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 26942d864651SAl Viro unsigned int flags) 26952d864651SAl Viro { 2696cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 26972d864651SAl Viro } 26982d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 26992d864651SAl Viro 2700cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27011da177e4SLinus Torvalds { 27028e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2703da9592edSDavid Howells 27048e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27051da177e4SLinus Torvalds return 0; 27068e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27071da177e4SLinus Torvalds return 0; 270823adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27091da177e4SLinus Torvalds } 2710cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27111da177e4SLinus Torvalds 27121da177e4SLinus Torvalds /* 27131da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27141da177e4SLinus Torvalds * whether the type of victim is right. 27151da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27161da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27171da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27181da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27191da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27201da177e4SLinus Torvalds * a. be owner of dir, or 27211da177e4SLinus Torvalds * b. be owner of victim, or 27221da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27231da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27241da177e4SLinus Torvalds * links pointing to it. 27251da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27261da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27271da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 27281da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 27291da177e4SLinus Torvalds * nfs_async_unlink(). 27301da177e4SLinus Torvalds */ 2731b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27321da177e4SLinus Torvalds { 273363afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27341da177e4SLinus Torvalds int error; 27351da177e4SLinus Torvalds 2736b18825a7SDavid Howells if (d_is_negative(victim)) 27371da177e4SLinus Torvalds return -ENOENT; 2738b18825a7SDavid Howells BUG_ON(!inode); 27391da177e4SLinus Torvalds 27401da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27414fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27421da177e4SLinus Torvalds 2743f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27441da177e4SLinus Torvalds if (error) 27451da177e4SLinus Torvalds return error; 27461da177e4SLinus Torvalds if (IS_APPEND(dir)) 27471da177e4SLinus Torvalds return -EPERM; 2748b18825a7SDavid Howells 2749b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2750b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 27511da177e4SLinus Torvalds return -EPERM; 27521da177e4SLinus Torvalds if (isdir) { 275344b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27541da177e4SLinus Torvalds return -ENOTDIR; 27551da177e4SLinus Torvalds if (IS_ROOT(victim)) 27561da177e4SLinus Torvalds return -EBUSY; 275744b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27581da177e4SLinus Torvalds return -EISDIR; 27591da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27601da177e4SLinus Torvalds return -ENOENT; 27611da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27621da177e4SLinus Torvalds return -EBUSY; 27631da177e4SLinus Torvalds return 0; 27641da177e4SLinus Torvalds } 27651da177e4SLinus Torvalds 27661da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27671da177e4SLinus Torvalds * dir. 27681da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27691da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27701da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 27711da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 27721da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 27731da177e4SLinus Torvalds */ 2774a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27751da177e4SLinus Torvalds { 277614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27771da177e4SLinus Torvalds if (child->d_inode) 27781da177e4SLinus Torvalds return -EEXIST; 27791da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27801da177e4SLinus Torvalds return -ENOENT; 2781f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27821da177e4SLinus Torvalds } 27831da177e4SLinus Torvalds 27841da177e4SLinus Torvalds /* 27851da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27861da177e4SLinus Torvalds */ 27871da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27881da177e4SLinus Torvalds { 27891da177e4SLinus Torvalds struct dentry *p; 27901da177e4SLinus Torvalds 27911da177e4SLinus Torvalds if (p1 == p2) { 27925955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27931da177e4SLinus Torvalds return NULL; 27941da177e4SLinus Torvalds } 27951da177e4SLinus Torvalds 2796fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27971da177e4SLinus Torvalds 2798e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2799e2761a11SOGAWA Hirofumi if (p) { 28005955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28015955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28021da177e4SLinus Torvalds return p; 28031da177e4SLinus Torvalds } 28041da177e4SLinus Torvalds 2805e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2806e2761a11SOGAWA Hirofumi if (p) { 28075955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28085955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28091da177e4SLinus Torvalds return p; 28101da177e4SLinus Torvalds } 28111da177e4SLinus Torvalds 28125955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28135955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28141da177e4SLinus Torvalds return NULL; 28151da177e4SLinus Torvalds } 28164d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28171da177e4SLinus Torvalds 28181da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28191da177e4SLinus Torvalds { 28205955102cSAl Viro inode_unlock(p1->d_inode); 28211da177e4SLinus Torvalds if (p1 != p2) { 28225955102cSAl Viro inode_unlock(p2->d_inode); 2823fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28241da177e4SLinus Torvalds } 28251da177e4SLinus Torvalds } 28264d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28271da177e4SLinus Torvalds 28284acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2829312b63fbSAl Viro bool want_excl) 28301da177e4SLinus Torvalds { 2831a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28321da177e4SLinus Torvalds if (error) 28331da177e4SLinus Torvalds return error; 28341da177e4SLinus Torvalds 2835acfa4380SAl Viro if (!dir->i_op->create) 28361da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28371da177e4SLinus Torvalds mode &= S_IALLUGO; 28381da177e4SLinus Torvalds mode |= S_IFREG; 28391da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28401da177e4SLinus Torvalds if (error) 28411da177e4SLinus Torvalds return error; 2842312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2843a74574aaSStephen Smalley if (!error) 2844f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28451da177e4SLinus Torvalds return error; 28461da177e4SLinus Torvalds } 28474d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28481da177e4SLinus Torvalds 284973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 28501da177e4SLinus Torvalds { 28513fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28521da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28531da177e4SLinus Torvalds int error; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds if (!inode) 28561da177e4SLinus Torvalds return -ENOENT; 28571da177e4SLinus Torvalds 2858c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2859c8fe8f30SChristoph Hellwig case S_IFLNK: 28601da177e4SLinus Torvalds return -ELOOP; 2861c8fe8f30SChristoph Hellwig case S_IFDIR: 2862c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28631da177e4SLinus Torvalds return -EISDIR; 2864c8fe8f30SChristoph Hellwig break; 2865c8fe8f30SChristoph Hellwig case S_IFBLK: 2866c8fe8f30SChristoph Hellwig case S_IFCHR: 28673fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 28681da177e4SLinus Torvalds return -EACCES; 2869c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2870c8fe8f30SChristoph Hellwig case S_IFIFO: 2871c8fe8f30SChristoph Hellwig case S_IFSOCK: 28721da177e4SLinus Torvalds flag &= ~O_TRUNC; 2873c8fe8f30SChristoph Hellwig break; 28744a3fd211SDave Hansen } 2875b41572e9SDave Hansen 287662fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2877b41572e9SDave Hansen if (error) 2878b41572e9SDave Hansen return error; 28796146f0d5SMimi Zohar 28801da177e4SLinus Torvalds /* 28811da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28821da177e4SLinus Torvalds */ 28831da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28848737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28857715b521SAl Viro return -EPERM; 28861da177e4SLinus Torvalds if (flag & O_TRUNC) 28877715b521SAl Viro return -EPERM; 28881da177e4SLinus Torvalds } 28891da177e4SLinus Torvalds 28901da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28912e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28927715b521SAl Viro return -EPERM; 28931da177e4SLinus Torvalds 2894f3c7691eSJ. Bruce Fields return 0; 28957715b521SAl Viro } 28967715b521SAl Viro 2897e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28987715b521SAl Viro { 2899e1181ee6SJeff Layton struct path *path = &filp->f_path; 29007715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29017715b521SAl Viro int error = get_write_access(inode); 29021da177e4SLinus Torvalds if (error) 29037715b521SAl Viro return error; 29041da177e4SLinus Torvalds /* 29051da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29061da177e4SLinus Torvalds */ 2907d7a06983SJeff Layton error = locks_verify_locked(filp); 2908be6d3e56SKentaro Takeda if (!error) 2909ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29101da177e4SLinus Torvalds if (!error) { 29117715b521SAl Viro error = do_truncate(path->dentry, 0, 2912d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2913e1181ee6SJeff Layton filp); 29141da177e4SLinus Torvalds } 29151da177e4SLinus Torvalds put_write_access(inode); 2916acd0c935SMimi Zohar return error; 29171da177e4SLinus Torvalds } 29181da177e4SLinus Torvalds 2919d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2920d57999e1SDave Hansen { 29218a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29228a5e929dSAl Viro flag--; 2923d57999e1SDave Hansen return flag; 2924d57999e1SDave Hansen } 2925d57999e1SDave Hansen 2926d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2927d18e9008SMiklos Szeredi { 2928d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2929d18e9008SMiklos Szeredi if (error) 2930d18e9008SMiklos Szeredi return error; 2931d18e9008SMiklos Szeredi 2932d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2933d18e9008SMiklos Szeredi if (error) 2934d18e9008SMiklos Szeredi return error; 2935d18e9008SMiklos Szeredi 2936d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2937d18e9008SMiklos Szeredi } 2938d18e9008SMiklos Szeredi 29391acf0af9SDavid Howells /* 29401acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29411acf0af9SDavid Howells * dentry. 29421acf0af9SDavid Howells * 29431acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29441acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29451acf0af9SDavid Howells * 29461acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29471acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29481acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29491acf0af9SDavid Howells * 29501acf0af9SDavid Howells * Returns an error code otherwise. 29511acf0af9SDavid Howells */ 29522675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 295330d90494SAl Viro struct path *path, struct file *file, 2954015c3bbcSMiklos Szeredi const struct open_flags *op, 29551643b43fSAl Viro int open_flag, umode_t mode, 295647237687SAl Viro int *opened) 2957d18e9008SMiklos Szeredi { 2958d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2959d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2960d18e9008SMiklos Szeredi int error; 2961d18e9008SMiklos Szeredi 2962384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2963d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2964d18e9008SMiklos Szeredi 2965d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2966d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2967d18e9008SMiklos Szeredi 296830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 296930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29700fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 29710fb1ea09SAl Viro open_to_namei_flags(open_flag), 29720fb1ea09SAl Viro mode, opened); 29736fbd0714SAl Viro d_lookup_done(dentry); 2974384f26e2SAl Viro if (!error) { 2975d18e9008SMiklos Szeredi /* 2976384f26e2SAl Viro * We didn't have the inode before the open, so check open 2977384f26e2SAl Viro * permission here. 2978d18e9008SMiklos Szeredi */ 2979384f26e2SAl Viro int acc_mode = op->acc_mode; 298003da633aSAl Viro if (*opened & FILE_CREATED) { 298103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 298203da633aSAl Viro fsnotify_create(dir, dentry); 298362fb4a15SAl Viro acc_mode = 0; 298403da633aSAl Viro } 29852675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 2986384f26e2SAl Viro if (WARN_ON(error > 0)) 2987384f26e2SAl Viro error = -EINVAL; 2988384f26e2SAl Viro } else if (error > 0) { 2989d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2990d18e9008SMiklos Szeredi error = -EIO; 2991384f26e2SAl Viro } else { 2992d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2993d18e9008SMiklos Szeredi dput(dentry); 2994d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 299510c64ceaSAl Viro } 2996d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 2997d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2998d18e9008SMiklos Szeredi path->dentry = dentry; 2999d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30002675a4ebSAl Viro return 1; 3001d18e9008SMiklos Szeredi } 3002d18e9008SMiklos Szeredi } 3003d18e9008SMiklos Szeredi dput(dentry); 3004d18e9008SMiklos Szeredi return error; 3005d18e9008SMiklos Szeredi } 3006d18e9008SMiklos Szeredi 300731e6b01fSNick Piggin /* 30081acf0af9SDavid Howells * Look up and maybe create and open the last component. 3009d58ffd35SMiklos Szeredi * 3010d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3011d58ffd35SMiklos Szeredi * 30121acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30131acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30141acf0af9SDavid Howells * 30151acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30161acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30171acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30181acf0af9SDavid Howells * specified then a negative dentry may be returned. 30191acf0af9SDavid Howells * 30201acf0af9SDavid Howells * An error code is returned otherwise. 30211acf0af9SDavid Howells * 30221acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30231acf0af9SDavid Howells * cleared otherwise prior to returning. 3024d58ffd35SMiklos Szeredi */ 30252675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 302630d90494SAl Viro struct file *file, 3027d58ffd35SMiklos Szeredi const struct open_flags *op, 302864894cf8SAl Viro bool got_write, int *opened) 3029d58ffd35SMiklos Szeredi { 3030d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 303154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30321643b43fSAl Viro int open_flag = op->open_flag; 3033d58ffd35SMiklos Szeredi struct dentry *dentry; 30341643b43fSAl Viro int error, create_error = 0; 30351643b43fSAl Viro umode_t mode = op->mode; 30366fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3037d58ffd35SMiklos Szeredi 3038ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3039ce8644fcSAl Viro return -ENOENT; 3040d58ffd35SMiklos Szeredi 304147237687SAl Viro *opened &= ~FILE_CREATED; 30426fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30436fbd0714SAl Viro for (;;) { 30446fbd0714SAl Viro if (!dentry) { 30456fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3046d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30472675a4ebSAl Viro return PTR_ERR(dentry); 30486fbd0714SAl Viro } 30496fbd0714SAl Viro if (d_in_lookup(dentry)) 30506fbd0714SAl Viro break; 3051d58ffd35SMiklos Szeredi 30526fbd0714SAl Viro if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) 30536fbd0714SAl Viro break; 30546fbd0714SAl Viro 30556fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30566fbd0714SAl Viro if (likely(error > 0)) 30576fbd0714SAl Viro break; 30586fbd0714SAl Viro if (error) 30596fbd0714SAl Viro goto out_dput; 30606fbd0714SAl Viro d_invalidate(dentry); 30616fbd0714SAl Viro dput(dentry); 30626fbd0714SAl Viro dentry = NULL; 30636fbd0714SAl Viro } 30646fbd0714SAl Viro if (dentry->d_inode) { 3065d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3066d18e9008SMiklos Szeredi goto out_no_open; 30676c51e513SAl Viro } 3068d18e9008SMiklos Szeredi 30691643b43fSAl Viro /* 30701643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30711643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30721643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30731643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30741643b43fSAl Viro * 30751643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30761643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30771643b43fSAl Viro */ 30781643b43fSAl Viro if (open_flag & O_CREAT) { 30791643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30801643b43fSAl Viro mode &= ~current_umask(); 30811643b43fSAl Viro if (unlikely(!got_write)) { 30821643b43fSAl Viro create_error = -EROFS; 30831643b43fSAl Viro open_flag &= ~O_CREAT; 30841643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30851643b43fSAl Viro goto no_open; 30861643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30871643b43fSAl Viro } else { 30881643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30891643b43fSAl Viro if (create_error) { 30901643b43fSAl Viro open_flag &= ~O_CREAT; 30911643b43fSAl Viro if (open_flag & O_EXCL) 30921643b43fSAl Viro goto no_open; 30931643b43fSAl Viro } 30941643b43fSAl Viro } 30951643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30961643b43fSAl Viro unlikely(!got_write)) { 30971643b43fSAl Viro /* 30981643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30991643b43fSAl Viro * back to lookup + open 31001643b43fSAl Viro */ 31011643b43fSAl Viro goto no_open; 3102d18e9008SMiklos Szeredi } 3103d18e9008SMiklos Szeredi 31041643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31051643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31061643b43fSAl Viro mode, opened); 31071643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31081643b43fSAl Viro error = create_error; 31091643b43fSAl Viro return error; 31101643b43fSAl Viro } 311154ef4872SMiklos Szeredi 31121643b43fSAl Viro no_open: 31136fbd0714SAl Viro if (d_in_lookup(dentry)) { 311412fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 311512fa5e24SAl Viro nd->flags); 31166fbd0714SAl Viro d_lookup_done(dentry); 311712fa5e24SAl Viro if (unlikely(res)) { 311812fa5e24SAl Viro if (IS_ERR(res)) { 311912fa5e24SAl Viro error = PTR_ERR(res); 312012fa5e24SAl Viro goto out_dput; 312112fa5e24SAl Viro } 312212fa5e24SAl Viro dput(dentry); 312312fa5e24SAl Viro dentry = res; 312412fa5e24SAl Viro } 312554ef4872SMiklos Szeredi } 312654ef4872SMiklos Szeredi 3127d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31281643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 312947237687SAl Viro *opened |= FILE_CREATED; 3130ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3131ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3132ce8644fcSAl Viro error = -EACCES; 3133d58ffd35SMiklos Szeredi goto out_dput; 313477d660a8SMiklos Szeredi } 3135ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31361643b43fSAl Viro open_flag & O_EXCL); 3137d58ffd35SMiklos Szeredi if (error) 3138d58ffd35SMiklos Szeredi goto out_dput; 3139ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3140d58ffd35SMiklos Szeredi } 31411643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31421643b43fSAl Viro error = create_error; 3143d58ffd35SMiklos Szeredi goto out_dput; 3144d58ffd35SMiklos Szeredi } 3145d18e9008SMiklos Szeredi out_no_open: 3146d58ffd35SMiklos Szeredi path->dentry = dentry; 3147d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31482675a4ebSAl Viro return 1; 3149d58ffd35SMiklos Szeredi 3150d58ffd35SMiklos Szeredi out_dput: 3151d58ffd35SMiklos Szeredi dput(dentry); 31522675a4ebSAl Viro return error; 3153d58ffd35SMiklos Szeredi } 3154d58ffd35SMiklos Szeredi 3155d58ffd35SMiklos Szeredi /* 3156fe2d35ffSAl Viro * Handle the last step of open() 315731e6b01fSNick Piggin */ 3158896475d5SAl Viro static int do_last(struct nameidata *nd, 315930d90494SAl Viro struct file *file, const struct open_flags *op, 316076ae2a5aSAl Viro int *opened) 3161fb1cc555SAl Viro { 3162a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3163ca344a89SAl Viro int open_flag = op->open_flag; 316477d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 316564894cf8SAl Viro bool got_write = false; 3166bcda7652SAl Viro int acc_mode = op->acc_mode; 3167254cf582SAl Viro unsigned seq; 3168a1eb3315SMiklos Szeredi struct inode *inode; 316916b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3170896475d5SAl Viro struct path path; 317116b1c1cdSMiklos Szeredi bool retried = false; 317216c2cd71SAl Viro int error; 3173fb1cc555SAl Viro 3174c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3175c3e380b0SAl Viro nd->flags |= op->intent; 3176c3e380b0SAl Viro 3177bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3178fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3179deb106c6SAl Viro if (unlikely(error)) 31802675a4ebSAl Viro return error; 3181e83db167SMiklos Szeredi goto finish_open; 31821f36f774SAl Viro } 3183a2c36b45SAl Viro 3184ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3185fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3186fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3187fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3188254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3189e9742b53SAl Viro if (likely(error > 0)) 319071574865SMiklos Szeredi goto finish_lookup; 319171574865SMiklos Szeredi 3192ce57dfc1SAl Viro if (error < 0) 3193deb106c6SAl Viro return error; 3194a1eb3315SMiklos Szeredi 319537d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 31966583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3197b6183df7SMiklos Szeredi } else { 3198fe2d35ffSAl Viro /* create side of things */ 3199a3fbbde7SAl Viro /* 3200b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3201b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3202b6183df7SMiklos Szeredi * about to look up 3203a3fbbde7SAl Viro */ 32049f1fafeeSAl Viro error = complete_walk(nd); 3205e8bb73dfSAl Viro if (error) 32062675a4ebSAl Viro return error; 3207fe2d35ffSAl Viro 320876ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32091f36f774SAl Viro /* trailing slashes? */ 3210deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3211deb106c6SAl Viro return -EISDIR; 3212b6183df7SMiklos Szeredi } 32131f36f774SAl Viro 321416b1c1cdSMiklos Szeredi retry_lookup: 32159cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 321664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 321764894cf8SAl Viro if (!error) 321864894cf8SAl Viro got_write = true; 321964894cf8SAl Viro /* 322064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 322164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 322264894cf8SAl Viro * dropping this one anyway. 322364894cf8SAl Viro */ 322464894cf8SAl Viro } 32259cf843e3SAl Viro if (open_flag & O_CREAT) 32265955102cSAl Viro inode_lock(dir->d_inode); 32279cf843e3SAl Viro else 32289cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3229896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32309cf843e3SAl Viro if (open_flag & O_CREAT) 32315955102cSAl Viro inode_unlock(dir->d_inode); 32329cf843e3SAl Viro else 32339cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3234fb1cc555SAl Viro 32352675a4ebSAl Viro if (error <= 0) { 32362675a4ebSAl Viro if (error) 3237d58ffd35SMiklos Szeredi goto out; 32386c0d46c4SAl Viro 323947237687SAl Viro if ((*opened & FILE_CREATED) || 3240496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 324177d660a8SMiklos Szeredi will_truncate = false; 3242d18e9008SMiklos Szeredi 324376ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3244d18e9008SMiklos Szeredi goto opened; 3245d18e9008SMiklos Szeredi } 3246d18e9008SMiklos Szeredi 324747237687SAl Viro if (*opened & FILE_CREATED) { 32489b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3249ca344a89SAl Viro open_flag &= ~O_TRUNC; 325077d660a8SMiklos Szeredi will_truncate = false; 325162fb4a15SAl Viro acc_mode = 0; 3252896475d5SAl Viro path_to_nameidata(&path, nd); 3253e83db167SMiklos Szeredi goto finish_open_created; 3254fb1cc555SAl Viro } 3255fb1cc555SAl Viro 3256fb1cc555SAl Viro /* 3257d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3258d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3259d18e9008SMiklos Szeredi * necessary...) 3260d18e9008SMiklos Szeredi */ 326164894cf8SAl Viro if (got_write) { 3262d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 326364894cf8SAl Viro got_write = false; 3264d18e9008SMiklos Szeredi } 3265d18e9008SMiklos Szeredi 32666583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 32676583fe22SAl Viro path_to_nameidata(&path, nd); 32686583fe22SAl Viro return -ENOENT; 32696583fe22SAl Viro } 32706583fe22SAl Viro 32716583fe22SAl Viro /* 32726583fe22SAl Viro * create/update audit record if it already exists. 32736583fe22SAl Viro */ 32746583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 32756583fe22SAl Viro 3276deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3277deb106c6SAl Viro path_to_nameidata(&path, nd); 3278deb106c6SAl Viro return -EEXIST; 3279deb106c6SAl Viro } 3280fb1cc555SAl Viro 3281756daf26SNeilBrown error = follow_managed(&path, nd); 3282deb106c6SAl Viro if (unlikely(error < 0)) 3283deb106c6SAl Viro return error; 3284a3fbbde7SAl Viro 3285254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3286d4565649SAl Viro inode = d_backing_inode(path.dentry); 3287766c4cbfSAl Viro finish_lookup: 3288191d7f73SAl Viro if (nd->depth) 3289191d7f73SAl Viro put_link(nd); 3290181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3291181548c0SAl Viro inode, seq); 3292deb106c6SAl Viro if (unlikely(error)) 3293d63ff28fSAl Viro return error; 3294fb1cc555SAl Viro 3295896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3296896475d5SAl Viro path_to_nameidata(&path, nd); 329716b1c1cdSMiklos Szeredi } else { 329816b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3299896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3300896475d5SAl Viro nd->path.dentry = path.dentry; 330116b1c1cdSMiklos Szeredi 330216b1c1cdSMiklos Szeredi } 3303decf3400SMiklos Szeredi nd->inode = inode; 3304254cf582SAl Viro nd->seq = seq; 3305a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3306bc77daa7SAl Viro finish_open: 3307a3fbbde7SAl Viro error = complete_walk(nd); 330816b1c1cdSMiklos Szeredi if (error) { 330916b1c1cdSMiklos Szeredi path_put(&save_parent); 33102675a4ebSAl Viro return error; 331116b1c1cdSMiklos Szeredi } 331276ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3313fb1cc555SAl Viro error = -EISDIR; 331444b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33152675a4ebSAl Viro goto out; 3316af2f5542SMiklos Szeredi error = -ENOTDIR; 331744b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33182675a4ebSAl Viro goto out; 33194bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 332077d660a8SMiklos Szeredi will_truncate = false; 33216c0d46c4SAl Viro 33220f9d1a10SAl Viro if (will_truncate) { 33230f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33240f9d1a10SAl Viro if (error) 33252675a4ebSAl Viro goto out; 332664894cf8SAl Viro got_write = true; 33270f9d1a10SAl Viro } 3328e83db167SMiklos Szeredi finish_open_created: 3329bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3330ca344a89SAl Viro if (error) 33312675a4ebSAl Viro goto out; 33324aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33334aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 33344aa7c634SMiklos Szeredi if (!error) { 33354aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 33364aa7c634SMiklos Szeredi } else { 333730d90494SAl Viro if (error == -EOPENSTALE) 3338f60dc3dbSMiklos Szeredi goto stale_open; 3339015c3bbcSMiklos Szeredi goto out; 3340f60dc3dbSMiklos Szeredi } 3341a8277b9bSMiklos Szeredi opened: 33422675a4ebSAl Viro error = open_check_o_direct(file); 3343fe9ec829SAl Viro if (!error) 33443034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3345fe9ec829SAl Viro if (!error && will_truncate) 33462675a4ebSAl Viro error = handle_truncate(file); 3347ca344a89SAl Viro out: 3348fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3349fe9ec829SAl Viro fput(file); 3350c80567c8SAl Viro if (unlikely(error > 0)) { 3351c80567c8SAl Viro WARN_ON(1); 3352c80567c8SAl Viro error = -EINVAL; 3353c80567c8SAl Viro } 335464894cf8SAl Viro if (got_write) 33550f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 335616b1c1cdSMiklos Szeredi path_put(&save_parent); 33572675a4ebSAl Viro return error; 3358fb1cc555SAl Viro 3359f60dc3dbSMiklos Szeredi stale_open: 3360f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3361f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3362f60dc3dbSMiklos Szeredi goto out; 3363f60dc3dbSMiklos Szeredi 3364f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3365f60dc3dbSMiklos Szeredi path_put(&nd->path); 3366f60dc3dbSMiklos Szeredi nd->path = save_parent; 3367f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3368f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3369f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 337064894cf8SAl Viro if (got_write) { 3371f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 337264894cf8SAl Viro got_write = false; 3373f60dc3dbSMiklos Szeredi } 3374f60dc3dbSMiklos Szeredi retried = true; 3375f60dc3dbSMiklos Szeredi goto retry_lookup; 3376fb1cc555SAl Viro } 3377fb1cc555SAl Viro 3378c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 337960545d0dSAl Viro const struct open_flags *op, 338060545d0dSAl Viro struct file *file, int *opened) 338160545d0dSAl Viro { 338260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3383625b6d10SAl Viro struct dentry *child; 338460545d0dSAl Viro struct inode *dir; 3385625b6d10SAl Viro struct path path; 3386c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 338760545d0dSAl Viro if (unlikely(error)) 338860545d0dSAl Viro return error; 3389625b6d10SAl Viro error = mnt_want_write(path.mnt); 339060545d0dSAl Viro if (unlikely(error)) 339160545d0dSAl Viro goto out; 3392625b6d10SAl Viro dir = path.dentry->d_inode; 339360545d0dSAl Viro /* we want directory to be writable */ 3394625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 339560545d0dSAl Viro if (error) 339660545d0dSAl Viro goto out2; 339760545d0dSAl Viro if (!dir->i_op->tmpfile) { 339860545d0dSAl Viro error = -EOPNOTSUPP; 339960545d0dSAl Viro goto out2; 340060545d0dSAl Viro } 3401625b6d10SAl Viro child = d_alloc(path.dentry, &name); 340260545d0dSAl Viro if (unlikely(!child)) { 340360545d0dSAl Viro error = -ENOMEM; 340460545d0dSAl Viro goto out2; 340560545d0dSAl Viro } 3406625b6d10SAl Viro dput(path.dentry); 3407625b6d10SAl Viro path.dentry = child; 3408625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 340960545d0dSAl Viro if (error) 341060545d0dSAl Viro goto out2; 3411c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 341269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 341362fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 341460545d0dSAl Viro if (error) 341560545d0dSAl Viro goto out2; 3416625b6d10SAl Viro file->f_path.mnt = path.mnt; 3417625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 341860545d0dSAl Viro if (error) 341960545d0dSAl Viro goto out2; 342060545d0dSAl Viro error = open_check_o_direct(file); 3421f4e0c30cSAl Viro if (error) { 342260545d0dSAl Viro fput(file); 3423f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3424f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3425f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3426f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3427f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3428f4e0c30cSAl Viro } 342960545d0dSAl Viro out2: 3430625b6d10SAl Viro mnt_drop_write(path.mnt); 343160545d0dSAl Viro out: 3432625b6d10SAl Viro path_put(&path); 343360545d0dSAl Viro return error; 343460545d0dSAl Viro } 343560545d0dSAl Viro 34366ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34376ac08709SAl Viro { 34386ac08709SAl Viro struct path path; 34396ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34406ac08709SAl Viro if (!error) { 34416ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34426ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34436ac08709SAl Viro path_put(&path); 34446ac08709SAl Viro } 34456ac08709SAl Viro return error; 34466ac08709SAl Viro } 34476ac08709SAl Viro 3448c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3449c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34501da177e4SLinus Torvalds { 3451368ee9baSAl Viro const char *s; 345230d90494SAl Viro struct file *file; 345347237687SAl Viro int opened = 0; 345413aab428SAl Viro int error; 345531e6b01fSNick Piggin 345630d90494SAl Viro file = get_empty_filp(); 34571afc99beSAl Viro if (IS_ERR(file)) 34581afc99beSAl Viro return file; 345931e6b01fSNick Piggin 346030d90494SAl Viro file->f_flags = op->open_flag; 346131e6b01fSNick Piggin 3462bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3463c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3464f15133dfSAl Viro goto out2; 346560545d0dSAl Viro } 346660545d0dSAl Viro 34676ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 34686ac08709SAl Viro error = do_o_path(nd, flags, file); 34696ac08709SAl Viro if (!error) 34706ac08709SAl Viro opened |= FILE_OPENED; 34716ac08709SAl Viro goto out2; 34726ac08709SAl Viro } 34736ac08709SAl Viro 3474c8a53ee5SAl Viro s = path_init(nd, flags); 3475368ee9baSAl Viro if (IS_ERR(s)) { 3476368ee9baSAl Viro put_filp(file); 3477368ee9baSAl Viro return ERR_CAST(s); 3478368ee9baSAl Viro } 34793bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 348076ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 348173d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 34823bdba28bSAl Viro s = trailing_symlink(nd); 34833bdba28bSAl Viro if (IS_ERR(s)) { 34843bdba28bSAl Viro error = PTR_ERR(s); 34852675a4ebSAl Viro break; 3486806b681cSAl Viro } 34873bdba28bSAl Viro } 3488deb106c6SAl Viro terminate_walk(nd); 3489f15133dfSAl Viro out2: 34902675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 34912675a4ebSAl Viro BUG_ON(!error); 349230d90494SAl Viro put_filp(file); 3493015c3bbcSMiklos Szeredi } 34942675a4ebSAl Viro if (unlikely(error)) { 34952675a4ebSAl Viro if (error == -EOPENSTALE) { 34962675a4ebSAl Viro if (flags & LOOKUP_RCU) 34972675a4ebSAl Viro error = -ECHILD; 34982675a4ebSAl Viro else 34992675a4ebSAl Viro error = -ESTALE; 35002675a4ebSAl Viro } 35012675a4ebSAl Viro file = ERR_PTR(error); 35022675a4ebSAl Viro } 35032675a4ebSAl Viro return file; 3504de459215SKirill Korotaev } 35051da177e4SLinus Torvalds 3506669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3507f9652e10SAl Viro const struct open_flags *op) 350813aab428SAl Viro { 35099883d185SAl Viro struct nameidata nd; 3510f9652e10SAl Viro int flags = op->lookup_flags; 351113aab428SAl Viro struct file *filp; 351213aab428SAl Viro 35139883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3514c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 351513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3516c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 351713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3518c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35199883d185SAl Viro restore_nameidata(); 352013aab428SAl Viro return filp; 352113aab428SAl Viro } 352213aab428SAl Viro 352373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3524f9652e10SAl Viro const char *name, const struct open_flags *op) 352573d049a4SAl Viro { 35269883d185SAl Viro struct nameidata nd; 352773d049a4SAl Viro struct file *file; 352851689104SPaul Moore struct filename *filename; 3529f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 353073d049a4SAl Viro 353173d049a4SAl Viro nd.root.mnt = mnt; 353273d049a4SAl Viro nd.root.dentry = dentry; 353373d049a4SAl Viro 3534b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 353573d049a4SAl Viro return ERR_PTR(-ELOOP); 353673d049a4SAl Viro 353751689104SPaul Moore filename = getname_kernel(name); 3538a1c83681SViresh Kumar if (IS_ERR(filename)) 353951689104SPaul Moore return ERR_CAST(filename); 354051689104SPaul Moore 35419883d185SAl Viro set_nameidata(&nd, -1, filename); 3542c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 354373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3544c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 354573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3546c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35479883d185SAl Viro restore_nameidata(); 354851689104SPaul Moore putname(filename); 354973d049a4SAl Viro return file; 355073d049a4SAl Viro } 355173d049a4SAl Viro 3552fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35531ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35541da177e4SLinus Torvalds { 3555c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3556391172c4SAl Viro struct qstr last; 3557391172c4SAl Viro int type; 3558c30dabfeSJan Kara int err2; 35591ac12b4bSJeff Layton int error; 35601ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35611ac12b4bSJeff Layton 35621ac12b4bSJeff Layton /* 35631ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35641ac12b4bSJeff Layton * other flags passed in are ignored! 35651ac12b4bSJeff Layton */ 35661ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35671ac12b4bSJeff Layton 35685c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35695c31b6ceSAl Viro if (IS_ERR(name)) 35705c31b6ceSAl Viro return ERR_CAST(name); 35711da177e4SLinus Torvalds 3572c663e5d8SChristoph Hellwig /* 3573c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3574c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3575c663e5d8SChristoph Hellwig */ 35765c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3577ed75e95dSAl Viro goto out; 3578c663e5d8SChristoph Hellwig 3579c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3580391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3581c663e5d8SChristoph Hellwig /* 3582c663e5d8SChristoph Hellwig * Do the final lookup. 3583c663e5d8SChristoph Hellwig */ 3584391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35855955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3586391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35871da177e4SLinus Torvalds if (IS_ERR(dentry)) 3588a8104a9fSAl Viro goto unlock; 3589c663e5d8SChristoph Hellwig 3590a8104a9fSAl Viro error = -EEXIST; 3591b18825a7SDavid Howells if (d_is_positive(dentry)) 3592a8104a9fSAl Viro goto fail; 3593b18825a7SDavid Howells 3594c663e5d8SChristoph Hellwig /* 3595c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3596c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3597c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3598c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3599c663e5d8SChristoph Hellwig */ 3600391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3601a8104a9fSAl Viro error = -ENOENT; 3602ed75e95dSAl Viro goto fail; 3603e9baf6e5SAl Viro } 3604c30dabfeSJan Kara if (unlikely(err2)) { 3605c30dabfeSJan Kara error = err2; 3606a8104a9fSAl Viro goto fail; 3607c30dabfeSJan Kara } 3608181c37b6SAl Viro putname(name); 3609e9baf6e5SAl Viro return dentry; 36101da177e4SLinus Torvalds fail: 3611a8104a9fSAl Viro dput(dentry); 3612a8104a9fSAl Viro dentry = ERR_PTR(error); 3613a8104a9fSAl Viro unlock: 36145955102cSAl Viro inode_unlock(path->dentry->d_inode); 3615c30dabfeSJan Kara if (!err2) 3616391172c4SAl Viro mnt_drop_write(path->mnt); 3617ed75e95dSAl Viro out: 3618391172c4SAl Viro path_put(path); 3619181c37b6SAl Viro putname(name); 3620ed75e95dSAl Viro return dentry; 3621dae6ad8fSAl Viro } 3622fa14a0b8SAl Viro 3623fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3624fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3625fa14a0b8SAl Viro { 3626181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3627181c37b6SAl Viro path, lookup_flags); 3628fa14a0b8SAl Viro } 3629dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3630dae6ad8fSAl Viro 3631921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3632921a1650SAl Viro { 3633921a1650SAl Viro dput(dentry); 36345955102cSAl Viro inode_unlock(path->dentry->d_inode); 3635a8104a9fSAl Viro mnt_drop_write(path->mnt); 3636921a1650SAl Viro path_put(path); 3637921a1650SAl Viro } 3638921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3639921a1650SAl Viro 3640520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36411ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3642dae6ad8fSAl Viro { 3643181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3644dae6ad8fSAl Viro } 3645dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3646dae6ad8fSAl Viro 36471a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36481da177e4SLinus Torvalds { 3649a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36501da177e4SLinus Torvalds 36511da177e4SLinus Torvalds if (error) 36521da177e4SLinus Torvalds return error; 36531da177e4SLinus Torvalds 3654975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36551da177e4SLinus Torvalds return -EPERM; 36561da177e4SLinus Torvalds 3657acfa4380SAl Viro if (!dir->i_op->mknod) 36581da177e4SLinus Torvalds return -EPERM; 36591da177e4SLinus Torvalds 366008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 366108ce5f16SSerge E. Hallyn if (error) 366208ce5f16SSerge E. Hallyn return error; 366308ce5f16SSerge E. Hallyn 36641da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36651da177e4SLinus Torvalds if (error) 36661da177e4SLinus Torvalds return error; 36671da177e4SLinus Torvalds 36681da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3669a74574aaSStephen Smalley if (!error) 3670f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36711da177e4SLinus Torvalds return error; 36721da177e4SLinus Torvalds } 36734d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36741da177e4SLinus Torvalds 3675f69aac00SAl Viro static int may_mknod(umode_t mode) 3676463c3197SDave Hansen { 3677463c3197SDave Hansen switch (mode & S_IFMT) { 3678463c3197SDave Hansen case S_IFREG: 3679463c3197SDave Hansen case S_IFCHR: 3680463c3197SDave Hansen case S_IFBLK: 3681463c3197SDave Hansen case S_IFIFO: 3682463c3197SDave Hansen case S_IFSOCK: 3683463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3684463c3197SDave Hansen return 0; 3685463c3197SDave Hansen case S_IFDIR: 3686463c3197SDave Hansen return -EPERM; 3687463c3197SDave Hansen default: 3688463c3197SDave Hansen return -EINVAL; 3689463c3197SDave Hansen } 3690463c3197SDave Hansen } 3691463c3197SDave Hansen 36928208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 36932e4d0924SHeiko Carstens unsigned, dev) 36941da177e4SLinus Torvalds { 36951da177e4SLinus Torvalds struct dentry *dentry; 3696dae6ad8fSAl Viro struct path path; 3697dae6ad8fSAl Viro int error; 3698972567f1SJeff Layton unsigned int lookup_flags = 0; 36991da177e4SLinus Torvalds 37008e4bfca1SAl Viro error = may_mknod(mode); 37018e4bfca1SAl Viro if (error) 37028e4bfca1SAl Viro return error; 3703972567f1SJeff Layton retry: 3704972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3705dae6ad8fSAl Viro if (IS_ERR(dentry)) 3706dae6ad8fSAl Viro return PTR_ERR(dentry); 37072ad94ae6SAl Viro 3708dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3709ce3b0f8dSAl Viro mode &= ~current_umask(); 3710dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3711be6d3e56SKentaro Takeda if (error) 3712a8104a9fSAl Viro goto out; 37131da177e4SLinus Torvalds switch (mode & S_IFMT) { 37141da177e4SLinus Torvalds case 0: case S_IFREG: 3715312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 371605d1a717SMimi Zohar if (!error) 371705d1a717SMimi Zohar ima_post_path_mknod(dentry); 37181da177e4SLinus Torvalds break; 37191da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3720dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37211da177e4SLinus Torvalds new_decode_dev(dev)); 37221da177e4SLinus Torvalds break; 37231da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3724dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37251da177e4SLinus Torvalds break; 37261da177e4SLinus Torvalds } 3727a8104a9fSAl Viro out: 3728921a1650SAl Viro done_path_create(&path, dentry); 3729972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3730972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3731972567f1SJeff Layton goto retry; 3732972567f1SJeff Layton } 37331da177e4SLinus Torvalds return error; 37341da177e4SLinus Torvalds } 37351da177e4SLinus Torvalds 37368208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37375590ff0dSUlrich Drepper { 37385590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37395590ff0dSUlrich Drepper } 37405590ff0dSUlrich Drepper 374118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37421da177e4SLinus Torvalds { 3743a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37448de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37451da177e4SLinus Torvalds 37461da177e4SLinus Torvalds if (error) 37471da177e4SLinus Torvalds return error; 37481da177e4SLinus Torvalds 3749acfa4380SAl Viro if (!dir->i_op->mkdir) 37501da177e4SLinus Torvalds return -EPERM; 37511da177e4SLinus Torvalds 37521da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37531da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37541da177e4SLinus Torvalds if (error) 37551da177e4SLinus Torvalds return error; 37561da177e4SLinus Torvalds 37578de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37588de52778SAl Viro return -EMLINK; 37598de52778SAl Viro 37601da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3761a74574aaSStephen Smalley if (!error) 3762f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37631da177e4SLinus Torvalds return error; 37641da177e4SLinus Torvalds } 37654d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37661da177e4SLinus Torvalds 3767a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37681da177e4SLinus Torvalds { 37696902d925SDave Hansen struct dentry *dentry; 3770dae6ad8fSAl Viro struct path path; 3771dae6ad8fSAl Viro int error; 3772b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37731da177e4SLinus Torvalds 3774b76d8b82SJeff Layton retry: 3775b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37766902d925SDave Hansen if (IS_ERR(dentry)) 3777dae6ad8fSAl Viro return PTR_ERR(dentry); 37786902d925SDave Hansen 3779dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3780ce3b0f8dSAl Viro mode &= ~current_umask(); 3781dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3782a8104a9fSAl Viro if (!error) 3783dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3784921a1650SAl Viro done_path_create(&path, dentry); 3785b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3786b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3787b76d8b82SJeff Layton goto retry; 3788b76d8b82SJeff Layton } 37891da177e4SLinus Torvalds return error; 37901da177e4SLinus Torvalds } 37911da177e4SLinus Torvalds 3792a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37935590ff0dSUlrich Drepper { 37945590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 37955590ff0dSUlrich Drepper } 37965590ff0dSUlrich Drepper 37971da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37981da177e4SLinus Torvalds { 37991da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38001da177e4SLinus Torvalds 38011da177e4SLinus Torvalds if (error) 38021da177e4SLinus Torvalds return error; 38031da177e4SLinus Torvalds 3804acfa4380SAl Viro if (!dir->i_op->rmdir) 38051da177e4SLinus Torvalds return -EPERM; 38061da177e4SLinus Torvalds 38071d2ef590SAl Viro dget(dentry); 38085955102cSAl Viro inode_lock(dentry->d_inode); 3809912dbc15SSage Weil 38101da177e4SLinus Torvalds error = -EBUSY; 38117af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3812912dbc15SSage Weil goto out; 3813912dbc15SSage Weil 38141da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3815912dbc15SSage Weil if (error) 3816912dbc15SSage Weil goto out; 3817912dbc15SSage Weil 38183cebde24SSage Weil shrink_dcache_parent(dentry); 38191da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3820912dbc15SSage Weil if (error) 3821912dbc15SSage Weil goto out; 3822912dbc15SSage Weil 38231da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3824d83c49f3SAl Viro dont_mount(dentry); 38258ed936b5SEric W. Biederman detach_mounts(dentry); 38261da177e4SLinus Torvalds 3827912dbc15SSage Weil out: 38285955102cSAl Viro inode_unlock(dentry->d_inode); 38291d2ef590SAl Viro dput(dentry); 3830912dbc15SSage Weil if (!error) 3831912dbc15SSage Weil d_delete(dentry); 38321da177e4SLinus Torvalds return error; 38331da177e4SLinus Torvalds } 38344d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38351da177e4SLinus Torvalds 38365590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38371da177e4SLinus Torvalds { 38381da177e4SLinus Torvalds int error = 0; 383991a27b2aSJeff Layton struct filename *name; 38401da177e4SLinus Torvalds struct dentry *dentry; 3841f5beed75SAl Viro struct path path; 3842f5beed75SAl Viro struct qstr last; 3843f5beed75SAl Viro int type; 3844c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3845c6ee9206SJeff Layton retry: 3846f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3847f5beed75SAl Viro &path, &last, &type, lookup_flags); 384891a27b2aSJeff Layton if (IS_ERR(name)) 384991a27b2aSJeff Layton return PTR_ERR(name); 38501da177e4SLinus Torvalds 3851f5beed75SAl Viro switch (type) { 38521da177e4SLinus Torvalds case LAST_DOTDOT: 38531da177e4SLinus Torvalds error = -ENOTEMPTY; 38541da177e4SLinus Torvalds goto exit1; 38551da177e4SLinus Torvalds case LAST_DOT: 38561da177e4SLinus Torvalds error = -EINVAL; 38571da177e4SLinus Torvalds goto exit1; 38581da177e4SLinus Torvalds case LAST_ROOT: 38591da177e4SLinus Torvalds error = -EBUSY; 38601da177e4SLinus Torvalds goto exit1; 38611da177e4SLinus Torvalds } 38620612d9fbSOGAWA Hirofumi 3863f5beed75SAl Viro error = mnt_want_write(path.mnt); 3864c30dabfeSJan Kara if (error) 3865c30dabfeSJan Kara goto exit1; 38660612d9fbSOGAWA Hirofumi 38675955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3868f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38691da177e4SLinus Torvalds error = PTR_ERR(dentry); 38706902d925SDave Hansen if (IS_ERR(dentry)) 38716902d925SDave Hansen goto exit2; 3872e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3873e6bc45d6STheodore Ts'o error = -ENOENT; 3874e6bc45d6STheodore Ts'o goto exit3; 3875e6bc45d6STheodore Ts'o } 3876f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3877be6d3e56SKentaro Takeda if (error) 3878c30dabfeSJan Kara goto exit3; 3879f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38800622753bSDave Hansen exit3: 38811da177e4SLinus Torvalds dput(dentry); 38826902d925SDave Hansen exit2: 38835955102cSAl Viro inode_unlock(path.dentry->d_inode); 3884f5beed75SAl Viro mnt_drop_write(path.mnt); 38851da177e4SLinus Torvalds exit1: 3886f5beed75SAl Viro path_put(&path); 38871da177e4SLinus Torvalds putname(name); 3888c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3889c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3890c6ee9206SJeff Layton goto retry; 3891c6ee9206SJeff Layton } 38921da177e4SLinus Torvalds return error; 38931da177e4SLinus Torvalds } 38941da177e4SLinus Torvalds 38953cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38965590ff0dSUlrich Drepper { 38975590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38985590ff0dSUlrich Drepper } 38995590ff0dSUlrich Drepper 3900b21996e3SJ. Bruce Fields /** 3901b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3902b21996e3SJ. Bruce Fields * @dir: parent directory 3903b21996e3SJ. Bruce Fields * @dentry: victim 3904b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3905b21996e3SJ. Bruce Fields * 3906b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3907b21996e3SJ. Bruce Fields * 3908b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3909b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3910b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3911b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3912b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3913b21996e3SJ. Bruce Fields * 3914b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3915b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3916b21996e3SJ. Bruce Fields * to be NFS exported. 3917b21996e3SJ. Bruce Fields */ 3918b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39191da177e4SLinus Torvalds { 39209accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39211da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39221da177e4SLinus Torvalds 39231da177e4SLinus Torvalds if (error) 39241da177e4SLinus Torvalds return error; 39251da177e4SLinus Torvalds 3926acfa4380SAl Viro if (!dir->i_op->unlink) 39271da177e4SLinus Torvalds return -EPERM; 39281da177e4SLinus Torvalds 39295955102cSAl Viro inode_lock(target); 39308ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39311da177e4SLinus Torvalds error = -EBUSY; 39321da177e4SLinus Torvalds else { 39331da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3934bec1052eSAl Viro if (!error) { 39355a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39365a14696cSJ. Bruce Fields if (error) 3937b21996e3SJ. Bruce Fields goto out; 39381da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39398ed936b5SEric W. Biederman if (!error) { 3940d83c49f3SAl Viro dont_mount(dentry); 39418ed936b5SEric W. Biederman detach_mounts(dentry); 39428ed936b5SEric W. Biederman } 3943bec1052eSAl Viro } 39441da177e4SLinus Torvalds } 3945b21996e3SJ. Bruce Fields out: 39465955102cSAl Viro inode_unlock(target); 39471da177e4SLinus Torvalds 39481da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39491da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39509accbb97SJ. Bruce Fields fsnotify_link_count(target); 39511da177e4SLinus Torvalds d_delete(dentry); 39521da177e4SLinus Torvalds } 39530eeca283SRobert Love 39541da177e4SLinus Torvalds return error; 39551da177e4SLinus Torvalds } 39564d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39571da177e4SLinus Torvalds 39581da177e4SLinus Torvalds /* 39591da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39601b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39611da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39621da177e4SLinus Torvalds * while waiting on the I/O. 39631da177e4SLinus Torvalds */ 39645590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 39651da177e4SLinus Torvalds { 39662ad94ae6SAl Viro int error; 396791a27b2aSJeff Layton struct filename *name; 39681da177e4SLinus Torvalds struct dentry *dentry; 3969f5beed75SAl Viro struct path path; 3970f5beed75SAl Viro struct qstr last; 3971f5beed75SAl Viro int type; 39721da177e4SLinus Torvalds struct inode *inode = NULL; 3973b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39745d18f813SJeff Layton unsigned int lookup_flags = 0; 39755d18f813SJeff Layton retry: 3976f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3977f5beed75SAl Viro &path, &last, &type, lookup_flags); 397891a27b2aSJeff Layton if (IS_ERR(name)) 397991a27b2aSJeff Layton return PTR_ERR(name); 39802ad94ae6SAl Viro 39811da177e4SLinus Torvalds error = -EISDIR; 3982f5beed75SAl Viro if (type != LAST_NORM) 39831da177e4SLinus Torvalds goto exit1; 39840612d9fbSOGAWA Hirofumi 3985f5beed75SAl Viro error = mnt_want_write(path.mnt); 3986c30dabfeSJan Kara if (error) 3987c30dabfeSJan Kara goto exit1; 3988b21996e3SJ. Bruce Fields retry_deleg: 39895955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3990f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39911da177e4SLinus Torvalds error = PTR_ERR(dentry); 39921da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39931da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3994f5beed75SAl Viro if (last.name[last.len]) 399550338b88STörök Edwin goto slashes; 39961da177e4SLinus Torvalds inode = dentry->d_inode; 3997b18825a7SDavid Howells if (d_is_negative(dentry)) 3998e6bc45d6STheodore Ts'o goto slashes; 39997de9c6eeSAl Viro ihold(inode); 4000f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4001be6d3e56SKentaro Takeda if (error) 4002c30dabfeSJan Kara goto exit2; 4003f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40041da177e4SLinus Torvalds exit2: 40051da177e4SLinus Torvalds dput(dentry); 40061da177e4SLinus Torvalds } 40075955102cSAl Viro inode_unlock(path.dentry->d_inode); 40081da177e4SLinus Torvalds if (inode) 40091da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4010b21996e3SJ. Bruce Fields inode = NULL; 4011b21996e3SJ. Bruce Fields if (delegated_inode) { 40125a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4013b21996e3SJ. Bruce Fields if (!error) 4014b21996e3SJ. Bruce Fields goto retry_deleg; 4015b21996e3SJ. Bruce Fields } 4016f5beed75SAl Viro mnt_drop_write(path.mnt); 40171da177e4SLinus Torvalds exit1: 4018f5beed75SAl Viro path_put(&path); 40191da177e4SLinus Torvalds putname(name); 40205d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40215d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40225d18f813SJeff Layton inode = NULL; 40235d18f813SJeff Layton goto retry; 40245d18f813SJeff Layton } 40251da177e4SLinus Torvalds return error; 40261da177e4SLinus Torvalds 40271da177e4SLinus Torvalds slashes: 4028b18825a7SDavid Howells if (d_is_negative(dentry)) 4029b18825a7SDavid Howells error = -ENOENT; 403044b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4031b18825a7SDavid Howells error = -EISDIR; 4032b18825a7SDavid Howells else 4033b18825a7SDavid Howells error = -ENOTDIR; 40341da177e4SLinus Torvalds goto exit2; 40351da177e4SLinus Torvalds } 40361da177e4SLinus Torvalds 40372e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40385590ff0dSUlrich Drepper { 40395590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40405590ff0dSUlrich Drepper return -EINVAL; 40415590ff0dSUlrich Drepper 40425590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40435590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40445590ff0dSUlrich Drepper 40455590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40465590ff0dSUlrich Drepper } 40475590ff0dSUlrich Drepper 40483480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40495590ff0dSUlrich Drepper { 40505590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40515590ff0dSUlrich Drepper } 40525590ff0dSUlrich Drepper 4053db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40541da177e4SLinus Torvalds { 4055a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40561da177e4SLinus Torvalds 40571da177e4SLinus Torvalds if (error) 40581da177e4SLinus Torvalds return error; 40591da177e4SLinus Torvalds 4060acfa4380SAl Viro if (!dir->i_op->symlink) 40611da177e4SLinus Torvalds return -EPERM; 40621da177e4SLinus Torvalds 40631da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40641da177e4SLinus Torvalds if (error) 40651da177e4SLinus Torvalds return error; 40661da177e4SLinus Torvalds 40671da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4068a74574aaSStephen Smalley if (!error) 4069f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40701da177e4SLinus Torvalds return error; 40711da177e4SLinus Torvalds } 40724d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40731da177e4SLinus Torvalds 40742e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40752e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40761da177e4SLinus Torvalds { 40772ad94ae6SAl Viro int error; 407891a27b2aSJeff Layton struct filename *from; 40796902d925SDave Hansen struct dentry *dentry; 4080dae6ad8fSAl Viro struct path path; 4081f46d3567SJeff Layton unsigned int lookup_flags = 0; 40821da177e4SLinus Torvalds 40831da177e4SLinus Torvalds from = getname(oldname); 40841da177e4SLinus Torvalds if (IS_ERR(from)) 40851da177e4SLinus Torvalds return PTR_ERR(from); 4086f46d3567SJeff Layton retry: 4087f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40881da177e4SLinus Torvalds error = PTR_ERR(dentry); 40896902d925SDave Hansen if (IS_ERR(dentry)) 4090dae6ad8fSAl Viro goto out_putname; 40916902d925SDave Hansen 409291a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4093a8104a9fSAl Viro if (!error) 409491a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4095921a1650SAl Viro done_path_create(&path, dentry); 4096f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4097f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4098f46d3567SJeff Layton goto retry; 4099f46d3567SJeff Layton } 41006902d925SDave Hansen out_putname: 41011da177e4SLinus Torvalds putname(from); 41021da177e4SLinus Torvalds return error; 41031da177e4SLinus Torvalds } 41041da177e4SLinus Torvalds 41053480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41065590ff0dSUlrich Drepper { 41075590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41085590ff0dSUlrich Drepper } 41095590ff0dSUlrich Drepper 4110146a8595SJ. Bruce Fields /** 4111146a8595SJ. Bruce Fields * vfs_link - create a new link 4112146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4113146a8595SJ. Bruce Fields * @dir: new parent 4114146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4115146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4116146a8595SJ. Bruce Fields * 4117146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4118146a8595SJ. Bruce Fields * 4119146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4120146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4121146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4122146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4123146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4124146a8595SJ. Bruce Fields * 4125146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4126146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4127146a8595SJ. Bruce Fields * to be NFS exported. 4128146a8595SJ. Bruce Fields */ 4129146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41301da177e4SLinus Torvalds { 41311da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41328de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41331da177e4SLinus Torvalds int error; 41341da177e4SLinus Torvalds 41351da177e4SLinus Torvalds if (!inode) 41361da177e4SLinus Torvalds return -ENOENT; 41371da177e4SLinus Torvalds 4138a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41391da177e4SLinus Torvalds if (error) 41401da177e4SLinus Torvalds return error; 41411da177e4SLinus Torvalds 41421da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41431da177e4SLinus Torvalds return -EXDEV; 41441da177e4SLinus Torvalds 41451da177e4SLinus Torvalds /* 41461da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41471da177e4SLinus Torvalds */ 41481da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41491da177e4SLinus Torvalds return -EPERM; 4150acfa4380SAl Viro if (!dir->i_op->link) 41511da177e4SLinus Torvalds return -EPERM; 41527e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41531da177e4SLinus Torvalds return -EPERM; 41541da177e4SLinus Torvalds 41551da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41561da177e4SLinus Torvalds if (error) 41571da177e4SLinus Torvalds return error; 41581da177e4SLinus Torvalds 41595955102cSAl Viro inode_lock(inode); 4160aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4161f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4162aae8a97dSAneesh Kumar K.V error = -ENOENT; 41638de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41648de52778SAl Viro error = -EMLINK; 4165146a8595SJ. Bruce Fields else { 4166146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4167146a8595SJ. Bruce Fields if (!error) 41681da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4169146a8595SJ. Bruce Fields } 4170f4e0c30cSAl Viro 4171f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4172f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4173f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4174f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4175f4e0c30cSAl Viro } 41765955102cSAl Viro inode_unlock(inode); 4177e31e14ecSStephen Smalley if (!error) 41787e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41791da177e4SLinus Torvalds return error; 41801da177e4SLinus Torvalds } 41814d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41821da177e4SLinus Torvalds 41831da177e4SLinus Torvalds /* 41841da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41851da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41861da177e4SLinus Torvalds * newname. --KAB 41871da177e4SLinus Torvalds * 41881da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41891da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41901da177e4SLinus Torvalds * and other special files. --ADM 41911da177e4SLinus Torvalds */ 41922e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 41932e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 41941da177e4SLinus Torvalds { 41951da177e4SLinus Torvalds struct dentry *new_dentry; 4196dae6ad8fSAl Viro struct path old_path, new_path; 4197146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 419811a7b371SAneesh Kumar K.V int how = 0; 41991da177e4SLinus Torvalds int error; 42001da177e4SLinus Torvalds 420111a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4202c04030e1SUlrich Drepper return -EINVAL; 420311a7b371SAneesh Kumar K.V /* 4204f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4205f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4206f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 420711a7b371SAneesh Kumar K.V */ 4208f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4209f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4210f0cc6ffbSLinus Torvalds return -ENOENT; 421111a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4212f0cc6ffbSLinus Torvalds } 4213c04030e1SUlrich Drepper 421411a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 421511a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4216442e31caSJeff Layton retry: 421711a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42181da177e4SLinus Torvalds if (error) 42192ad94ae6SAl Viro return error; 42202ad94ae6SAl Viro 4221442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4222442e31caSJeff Layton (how & LOOKUP_REVAL)); 42231da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42246902d925SDave Hansen if (IS_ERR(new_dentry)) 4225dae6ad8fSAl Viro goto out; 4226dae6ad8fSAl Viro 4227dae6ad8fSAl Viro error = -EXDEV; 4228dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4229dae6ad8fSAl Viro goto out_dput; 4230800179c9SKees Cook error = may_linkat(&old_path); 4231800179c9SKees Cook if (unlikely(error)) 4232800179c9SKees Cook goto out_dput; 4233dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4234be6d3e56SKentaro Takeda if (error) 4235a8104a9fSAl Viro goto out_dput; 4236146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 423775c3f29dSDave Hansen out_dput: 4238921a1650SAl Viro done_path_create(&new_path, new_dentry); 4239146a8595SJ. Bruce Fields if (delegated_inode) { 4240146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4241d22e6338SOleg Drokin if (!error) { 4242d22e6338SOleg Drokin path_put(&old_path); 4243146a8595SJ. Bruce Fields goto retry; 4244146a8595SJ. Bruce Fields } 4245d22e6338SOleg Drokin } 4246442e31caSJeff Layton if (retry_estale(error, how)) { 4247d22e6338SOleg Drokin path_put(&old_path); 4248442e31caSJeff Layton how |= LOOKUP_REVAL; 4249442e31caSJeff Layton goto retry; 4250442e31caSJeff Layton } 42511da177e4SLinus Torvalds out: 42522d8f3038SAl Viro path_put(&old_path); 42531da177e4SLinus Torvalds 42541da177e4SLinus Torvalds return error; 42551da177e4SLinus Torvalds } 42561da177e4SLinus Torvalds 42573480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42585590ff0dSUlrich Drepper { 4259c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42605590ff0dSUlrich Drepper } 42615590ff0dSUlrich Drepper 4262bc27027aSMiklos Szeredi /** 4263bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4264bc27027aSMiklos Szeredi * @old_dir: parent of source 4265bc27027aSMiklos Szeredi * @old_dentry: source 4266bc27027aSMiklos Szeredi * @new_dir: parent of destination 4267bc27027aSMiklos Szeredi * @new_dentry: destination 4268bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4269520c8b16SMiklos Szeredi * @flags: rename flags 4270bc27027aSMiklos Szeredi * 4271bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4272bc27027aSMiklos Szeredi * 4273bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4274bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4275bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4276bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4277bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4278bc27027aSMiklos Szeredi * so. 4279bc27027aSMiklos Szeredi * 4280bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4281bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4282bc27027aSMiklos Szeredi * to be NFS exported. 4283bc27027aSMiklos Szeredi * 42841da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42851da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42861da177e4SLinus Torvalds * Problems: 4287d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42881da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42891da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4290a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42911da177e4SLinus Torvalds * story. 42926cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42936cedba89SJ. Bruce Fields * and source (if it is not a directory). 42941b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42951da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42961da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4297a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42981da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42991da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43001da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4301a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43021da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43031da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43041da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4305e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43061b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43071da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4308c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43091da177e4SLinus Torvalds * locking]. 43101da177e4SLinus Torvalds */ 43111da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43128e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4313520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43141da177e4SLinus Torvalds { 43151da177e4SLinus Torvalds int error; 4316bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 431759b0df21SEric Paris const unsigned char *old_name; 4318bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4319bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4320da1ce067SMiklos Szeredi bool new_is_dir = false; 4321da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 43221da177e4SLinus Torvalds 43239409e22aSMiklos Szeredi /* 43249409e22aSMiklos Szeredi * Check source == target. 43259409e22aSMiklos Szeredi * On overlayfs need to look at underlying inodes. 43269409e22aSMiklos Szeredi */ 43279409e22aSMiklos Szeredi if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) 43281da177e4SLinus Torvalds return 0; 43291da177e4SLinus Torvalds 43301da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43311da177e4SLinus Torvalds if (error) 43321da177e4SLinus Torvalds return error; 43331da177e4SLinus Torvalds 4334da1ce067SMiklos Szeredi if (!target) { 4335a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4336da1ce067SMiklos Szeredi } else { 4337da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4338da1ce067SMiklos Szeredi 4339da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43401da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4341da1ce067SMiklos Szeredi else 4342da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4343da1ce067SMiklos Szeredi } 43441da177e4SLinus Torvalds if (error) 43451da177e4SLinus Torvalds return error; 43461da177e4SLinus Torvalds 43477177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 43481da177e4SLinus Torvalds return -EPERM; 43491da177e4SLinus Torvalds 4350520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4351520c8b16SMiklos Szeredi return -EINVAL; 4352520c8b16SMiklos Szeredi 4353bc27027aSMiklos Szeredi /* 4354bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4355bc27027aSMiklos Szeredi * we'll need to flip '..'. 4356bc27027aSMiklos Szeredi */ 4357da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4358da1ce067SMiklos Szeredi if (is_dir) { 4359bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4360bc27027aSMiklos Szeredi if (error) 4361bc27027aSMiklos Szeredi return error; 4362bc27027aSMiklos Szeredi } 4363da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4364da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4365da1ce067SMiklos Szeredi if (error) 4366da1ce067SMiklos Szeredi return error; 4367da1ce067SMiklos Szeredi } 4368da1ce067SMiklos Szeredi } 43690eeca283SRobert Love 43700b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43710b3974ebSMiklos Szeredi flags); 4372bc27027aSMiklos Szeredi if (error) 4373bc27027aSMiklos Szeredi return error; 4374bc27027aSMiklos Szeredi 4375bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4376bc27027aSMiklos Szeredi dget(new_dentry); 4377da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4378bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4379bc27027aSMiklos Szeredi else if (target) 43805955102cSAl Viro inode_lock(target); 4381bc27027aSMiklos Szeredi 4382bc27027aSMiklos Szeredi error = -EBUSY; 43837af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4384bc27027aSMiklos Szeredi goto out; 4385bc27027aSMiklos Szeredi 4386da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4387bc27027aSMiklos Szeredi error = -EMLINK; 4388da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4389bc27027aSMiklos Szeredi goto out; 4390da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4391da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4392da1ce067SMiklos Szeredi goto out; 4393da1ce067SMiklos Szeredi } 4394da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4395bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4396da1ce067SMiklos Szeredi if (!is_dir) { 4397bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4398bc27027aSMiklos Szeredi if (error) 4399bc27027aSMiklos Szeredi goto out; 4400da1ce067SMiklos Szeredi } 4401da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4402bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4403bc27027aSMiklos Szeredi if (error) 4404bc27027aSMiklos Szeredi goto out; 4405bc27027aSMiklos Szeredi } 44067177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4407520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4408520c8b16SMiklos Szeredi new_dir, new_dentry); 4409520c8b16SMiklos Szeredi } else { 44107177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4411520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4412520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4413520c8b16SMiklos Szeredi } 4414bc27027aSMiklos Szeredi if (error) 4415bc27027aSMiklos Szeredi goto out; 4416bc27027aSMiklos Szeredi 4417da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44181da177e4SLinus Torvalds if (is_dir) 4419bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4420bc27027aSMiklos Szeredi dont_mount(new_dentry); 44218ed936b5SEric W. Biederman detach_mounts(new_dentry); 4422bc27027aSMiklos Szeredi } 4423da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4424da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4425bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4426da1ce067SMiklos Szeredi else 4427da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4428da1ce067SMiklos Szeredi } 4429bc27027aSMiklos Szeredi out: 4430da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4431bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4432bc27027aSMiklos Szeredi else if (target) 44335955102cSAl Viro inode_unlock(target); 4434bc27027aSMiklos Szeredi dput(new_dentry); 4435da1ce067SMiklos Szeredi if (!error) { 4436123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4437da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4438da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4439da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4440da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4441da1ce067SMiklos Szeredi } 4442da1ce067SMiklos Szeredi } 44430eeca283SRobert Love fsnotify_oldname_free(old_name); 44440eeca283SRobert Love 44451da177e4SLinus Torvalds return error; 44461da177e4SLinus Torvalds } 44474d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44481da177e4SLinus Torvalds 4449520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4450520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44511da177e4SLinus Torvalds { 44521da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44531da177e4SLinus Torvalds struct dentry *trap; 4454f5beed75SAl Viro struct path old_path, new_path; 4455f5beed75SAl Viro struct qstr old_last, new_last; 4456f5beed75SAl Viro int old_type, new_type; 44578e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 445891a27b2aSJeff Layton struct filename *from; 445991a27b2aSJeff Layton struct filename *to; 4460f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4461c6a94284SJeff Layton bool should_retry = false; 44622ad94ae6SAl Viro int error; 4463520c8b16SMiklos Szeredi 44640d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4465da1ce067SMiklos Szeredi return -EINVAL; 4466da1ce067SMiklos Szeredi 44670d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44680d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4469520c8b16SMiklos Szeredi return -EINVAL; 4470520c8b16SMiklos Szeredi 44710d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44720d7a8555SMiklos Szeredi return -EPERM; 44730d7a8555SMiklos Szeredi 4474f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4475f5beed75SAl Viro target_flags = 0; 4476f5beed75SAl Viro 4477c6a94284SJeff Layton retry: 4478f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4479f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 448091a27b2aSJeff Layton if (IS_ERR(from)) { 448191a27b2aSJeff Layton error = PTR_ERR(from); 44821da177e4SLinus Torvalds goto exit; 448391a27b2aSJeff Layton } 44841da177e4SLinus Torvalds 4485f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4486f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 448791a27b2aSJeff Layton if (IS_ERR(to)) { 448891a27b2aSJeff Layton error = PTR_ERR(to); 44891da177e4SLinus Torvalds goto exit1; 449091a27b2aSJeff Layton } 44911da177e4SLinus Torvalds 44921da177e4SLinus Torvalds error = -EXDEV; 4493f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44941da177e4SLinus Torvalds goto exit2; 44951da177e4SLinus Torvalds 44961da177e4SLinus Torvalds error = -EBUSY; 4497f5beed75SAl Viro if (old_type != LAST_NORM) 44981da177e4SLinus Torvalds goto exit2; 44991da177e4SLinus Torvalds 45000a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45010a7c3937SMiklos Szeredi error = -EEXIST; 4502f5beed75SAl Viro if (new_type != LAST_NORM) 45031da177e4SLinus Torvalds goto exit2; 45041da177e4SLinus Torvalds 4505f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4506c30dabfeSJan Kara if (error) 4507c30dabfeSJan Kara goto exit2; 4508c30dabfeSJan Kara 45098e6d782cSJ. Bruce Fields retry_deleg: 4510f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45111da177e4SLinus Torvalds 4512f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45131da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45141da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45151da177e4SLinus Torvalds goto exit3; 45161da177e4SLinus Torvalds /* source must exist */ 45171da177e4SLinus Torvalds error = -ENOENT; 4518b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45191da177e4SLinus Torvalds goto exit4; 4520f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45211da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45221da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45231da177e4SLinus Torvalds goto exit4; 45240a7c3937SMiklos Szeredi error = -EEXIST; 45250a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45260a7c3937SMiklos Szeredi goto exit5; 4527da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4528da1ce067SMiklos Szeredi error = -ENOENT; 4529da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4530da1ce067SMiklos Szeredi goto exit5; 4531da1ce067SMiklos Szeredi 4532da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4533da1ce067SMiklos Szeredi error = -ENOTDIR; 4534f5beed75SAl Viro if (new_last.name[new_last.len]) 4535da1ce067SMiklos Szeredi goto exit5; 4536da1ce067SMiklos Szeredi } 4537da1ce067SMiklos Szeredi } 45380a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45390a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45400a7c3937SMiklos Szeredi error = -ENOTDIR; 4541f5beed75SAl Viro if (old_last.name[old_last.len]) 45420a7c3937SMiklos Szeredi goto exit5; 4543f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45440a7c3937SMiklos Szeredi goto exit5; 45450a7c3937SMiklos Szeredi } 45460a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45470a7c3937SMiklos Szeredi error = -EINVAL; 45480a7c3937SMiklos Szeredi if (old_dentry == trap) 45490a7c3937SMiklos Szeredi goto exit5; 45501da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4551da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45521da177e4SLinus Torvalds error = -ENOTEMPTY; 45531da177e4SLinus Torvalds if (new_dentry == trap) 45541da177e4SLinus Torvalds goto exit5; 45551da177e4SLinus Torvalds 4556f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4557f5beed75SAl Viro &new_path, new_dentry, flags); 4558be6d3e56SKentaro Takeda if (error) 4559c30dabfeSJan Kara goto exit5; 4560f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4561f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4562520c8b16SMiklos Szeredi &delegated_inode, flags); 45631da177e4SLinus Torvalds exit5: 45641da177e4SLinus Torvalds dput(new_dentry); 45651da177e4SLinus Torvalds exit4: 45661da177e4SLinus Torvalds dput(old_dentry); 45671da177e4SLinus Torvalds exit3: 4568f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45698e6d782cSJ. Bruce Fields if (delegated_inode) { 45708e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45718e6d782cSJ. Bruce Fields if (!error) 45728e6d782cSJ. Bruce Fields goto retry_deleg; 45738e6d782cSJ. Bruce Fields } 4574f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45751da177e4SLinus Torvalds exit2: 4576c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4577c6a94284SJeff Layton should_retry = true; 4578f5beed75SAl Viro path_put(&new_path); 45792ad94ae6SAl Viro putname(to); 45801da177e4SLinus Torvalds exit1: 4581f5beed75SAl Viro path_put(&old_path); 45821da177e4SLinus Torvalds putname(from); 4583c6a94284SJeff Layton if (should_retry) { 4584c6a94284SJeff Layton should_retry = false; 4585c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4586c6a94284SJeff Layton goto retry; 4587c6a94284SJeff Layton } 45882ad94ae6SAl Viro exit: 45891da177e4SLinus Torvalds return error; 45901da177e4SLinus Torvalds } 45911da177e4SLinus Torvalds 4592520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4593520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4594520c8b16SMiklos Szeredi { 4595520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4596520c8b16SMiklos Szeredi } 4597520c8b16SMiklos Szeredi 4598a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45995590ff0dSUlrich Drepper { 4600520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46015590ff0dSUlrich Drepper } 46025590ff0dSUlrich Drepper 4603787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4604787fb6bcSMiklos Szeredi { 4605787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4606787fb6bcSMiklos Szeredi if (error) 4607787fb6bcSMiklos Szeredi return error; 4608787fb6bcSMiklos Szeredi 4609787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4610787fb6bcSMiklos Szeredi return -EPERM; 4611787fb6bcSMiklos Szeredi 4612787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4613787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4614787fb6bcSMiklos Szeredi } 4615787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4616787fb6bcSMiklos Szeredi 46175d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46181da177e4SLinus Torvalds { 46195d826c84SAl Viro int len = PTR_ERR(link); 46201da177e4SLinus Torvalds if (IS_ERR(link)) 46211da177e4SLinus Torvalds goto out; 46221da177e4SLinus Torvalds 46231da177e4SLinus Torvalds len = strlen(link); 46241da177e4SLinus Torvalds if (len > (unsigned) buflen) 46251da177e4SLinus Torvalds len = buflen; 46261da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46271da177e4SLinus Torvalds len = -EFAULT; 46281da177e4SLinus Torvalds out: 46291da177e4SLinus Torvalds return len; 46301da177e4SLinus Torvalds } 46311da177e4SLinus Torvalds 46321da177e4SLinus Torvalds /* 46331da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46346b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46356b255391SAl Viro * for any given inode is up to filesystem. 46361da177e4SLinus Torvalds */ 46371da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 46381da177e4SLinus Torvalds { 4639fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46405f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46415f2c4179SAl Viro const char *link = inode->i_link; 4642694a1764SMarcin Slusarz int res; 4643cc314eefSLinus Torvalds 4644d4dee48bSAl Viro if (!link) { 4645fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4646680baacbSAl Viro if (IS_ERR(link)) 4647680baacbSAl Viro return PTR_ERR(link); 4648d4dee48bSAl Viro } 4649680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4650fceef393SAl Viro do_delayed_call(&done); 4651694a1764SMarcin Slusarz return res; 46521da177e4SLinus Torvalds } 46534d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 46541da177e4SLinus Torvalds 46551da177e4SLinus Torvalds /* get the link contents into pagecache */ 46566b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4657fceef393SAl Viro struct delayed_call *callback) 46581da177e4SLinus Torvalds { 4659ebd09abbSDuane Griffin char *kaddr; 46601da177e4SLinus Torvalds struct page *page; 46616b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46626b255391SAl Viro 4663d3883d4fSAl Viro if (!dentry) { 4664d3883d4fSAl Viro page = find_get_page(mapping, 0); 4665d3883d4fSAl Viro if (!page) 46666b255391SAl Viro return ERR_PTR(-ECHILD); 4667d3883d4fSAl Viro if (!PageUptodate(page)) { 4668d3883d4fSAl Viro put_page(page); 4669d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4670d3883d4fSAl Viro } 4671d3883d4fSAl Viro } else { 4672090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46731da177e4SLinus Torvalds if (IS_ERR(page)) 46746fe6900eSNick Piggin return (char*)page; 4675d3883d4fSAl Viro } 4676fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 467721fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 467821fc61c7SAl Viro kaddr = page_address(page); 46796b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4680ebd09abbSDuane Griffin return kaddr; 46811da177e4SLinus Torvalds } 46821da177e4SLinus Torvalds 46836b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46841da177e4SLinus Torvalds 4685fceef393SAl Viro void page_put_link(void *arg) 46861da177e4SLinus Torvalds { 4687fceef393SAl Viro put_page(arg); 46881da177e4SLinus Torvalds } 46894d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46901da177e4SLinus Torvalds 4691aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4692aa80deabSAl Viro { 4693fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46946b255391SAl Viro int res = readlink_copy(buffer, buflen, 46956b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4696fceef393SAl Viro &done)); 4697fceef393SAl Viro do_delayed_call(&done); 4698aa80deabSAl Viro return res; 4699aa80deabSAl Viro } 4700aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4701aa80deabSAl Viro 470254566b2cSNick Piggin /* 470354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 470454566b2cSNick Piggin */ 470554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47061da177e4SLinus Torvalds { 47071da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47080adb25d2SKirill Korotaev struct page *page; 4709afddba49SNick Piggin void *fsdata; 4710beb497abSDmitriy Monakhov int err; 471154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 471254566b2cSNick Piggin if (nofs) 471354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47141da177e4SLinus Torvalds 47157e53cac4SNeilBrown retry: 4716afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 471754566b2cSNick Piggin flags, &page, &fsdata); 47181da177e4SLinus Torvalds if (err) 4719afddba49SNick Piggin goto fail; 4720afddba49SNick Piggin 472121fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4722afddba49SNick Piggin 4723afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4724afddba49SNick Piggin page, fsdata); 47251da177e4SLinus Torvalds if (err < 0) 47261da177e4SLinus Torvalds goto fail; 4727afddba49SNick Piggin if (err < len-1) 4728afddba49SNick Piggin goto retry; 4729afddba49SNick Piggin 47301da177e4SLinus Torvalds mark_inode_dirty(inode); 47311da177e4SLinus Torvalds return 0; 47321da177e4SLinus Torvalds fail: 47331da177e4SLinus Torvalds return err; 47341da177e4SLinus Torvalds } 47354d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47361da177e4SLinus Torvalds 47370adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47380adb25d2SKirill Korotaev { 47390adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4740c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47410adb25d2SKirill Korotaev } 47424d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47430adb25d2SKirill Korotaev 474492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47451da177e4SLinus Torvalds .readlink = generic_readlink, 47466b255391SAl Viro .get_link = page_get_link, 47471da177e4SLinus Torvalds }; 47481da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4749