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; 9042d7f9e2aSSeth Forshee kuid_t puid; 905800179c9SKees Cook 906800179c9SKees Cook if (!sysctl_protected_symlinks) 907800179c9SKees Cook return 0; 908800179c9SKees Cook 909800179c9SKees Cook /* Allowed if owner and follower match. */ 910fceef393SAl Viro inode = nd->link_inode; 91181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 912800179c9SKees Cook return 0; 913800179c9SKees Cook 914800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 915aa65fa35SAl Viro parent = nd->inode; 916800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 917800179c9SKees Cook return 0; 918800179c9SKees Cook 919800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9202d7f9e2aSSeth Forshee puid = parent->i_uid; 9212d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 922800179c9SKees Cook return 0; 923800179c9SKees Cook 92431956502SAl Viro if (nd->flags & LOOKUP_RCU) 92531956502SAl Viro return -ECHILD; 92631956502SAl Viro 9271cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 928800179c9SKees Cook return -EACCES; 929800179c9SKees Cook } 930800179c9SKees Cook 931800179c9SKees Cook /** 932800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 933800179c9SKees Cook * @inode: the source inode to hardlink from 934800179c9SKees Cook * 935800179c9SKees Cook * Return false if at least one of the following conditions: 936800179c9SKees Cook * - inode is not a regular file 937800179c9SKees Cook * - inode is setuid 938800179c9SKees Cook * - inode is setgid and group-exec 939800179c9SKees Cook * - access failure for read and write 940800179c9SKees Cook * 941800179c9SKees Cook * Otherwise returns true. 942800179c9SKees Cook */ 943800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 944800179c9SKees Cook { 945800179c9SKees Cook umode_t mode = inode->i_mode; 946800179c9SKees Cook 947800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 948800179c9SKees Cook if (!S_ISREG(mode)) 949800179c9SKees Cook return false; 950800179c9SKees Cook 951800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 952800179c9SKees Cook if (mode & S_ISUID) 953800179c9SKees Cook return false; 954800179c9SKees Cook 955800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 956800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 957800179c9SKees Cook return false; 958800179c9SKees Cook 959800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 960800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 961800179c9SKees Cook return false; 962800179c9SKees Cook 963800179c9SKees Cook return true; 964800179c9SKees Cook } 965800179c9SKees Cook 966800179c9SKees Cook /** 967800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 968800179c9SKees Cook * @link: the source to hardlink from 969800179c9SKees Cook * 970800179c9SKees Cook * Block hardlink when all of: 971800179c9SKees Cook * - sysctl_protected_hardlinks enabled 972800179c9SKees Cook * - fsuid does not match inode 973800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 974f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 975800179c9SKees Cook * 976800179c9SKees Cook * Returns 0 if successful, -ve on error. 977800179c9SKees Cook */ 978800179c9SKees Cook static int may_linkat(struct path *link) 979800179c9SKees Cook { 980800179c9SKees Cook struct inode *inode; 981800179c9SKees Cook 982800179c9SKees Cook if (!sysctl_protected_hardlinks) 983800179c9SKees Cook return 0; 984800179c9SKees Cook 985800179c9SKees Cook inode = link->dentry->d_inode; 986800179c9SKees Cook 987800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 988800179c9SKees Cook * otherwise, it must be a safe source. 989800179c9SKees Cook */ 990f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 991800179c9SKees Cook return 0; 992800179c9SKees Cook 993a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 994800179c9SKees Cook return -EPERM; 995800179c9SKees Cook } 996800179c9SKees Cook 9973b2e7f75SAl Viro static __always_inline 9983b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9991da177e4SLinus Torvalds { 1000ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10011cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1002fceef393SAl Viro struct inode *inode = nd->link_inode; 10036d7b5aaeSAl Viro int error; 10040a959df5SAl Viro const char *res; 10051da177e4SLinus Torvalds 10068fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10078fa9dd24SNeilBrown touch_atime(&last->link); 10088fa9dd24SNeilBrown cond_resched(); 10098fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10108fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10118fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10128fa9dd24SNeilBrown touch_atime(&last->link); 10138fa9dd24SNeilBrown } 10148fa9dd24SNeilBrown 1015bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1016bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1017bda0be7aSNeilBrown if (unlikely(error)) 10186920a440SAl Viro return ERR_PTR(error); 101936f3b4f6SAl Viro 102086acdca1SAl Viro nd->last_type = LAST_BIND; 1021d4dee48bSAl Viro res = inode->i_link; 1022d4dee48bSAl Viro if (!res) { 1023fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1024fceef393SAl Viro struct delayed_call *); 1025fceef393SAl Viro get = inode->i_op->get_link; 10268c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1027fceef393SAl Viro res = get(NULL, inode, &last->done); 10286b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10298c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10308c1b4566SAl Viro return ERR_PTR(-ECHILD); 1031fceef393SAl Viro res = get(dentry, inode, &last->done); 10328c1b4566SAl Viro } 10336b255391SAl Viro } else { 1034fceef393SAl Viro res = get(dentry, inode, &last->done); 10356b255391SAl Viro } 1036fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1037fab51e8aSAl Viro return res; 10380a959df5SAl Viro } 1039fab51e8aSAl Viro if (*res == '/') { 1040fab51e8aSAl Viro if (!nd->root.mnt) 1041fab51e8aSAl Viro set_root(nd); 1042248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1043fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1044fab51e8aSAl Viro while (unlikely(*++res == '/')) 1045fab51e8aSAl Viro ; 1046fab51e8aSAl Viro } 1047fab51e8aSAl Viro if (!*res) 1048fab51e8aSAl Viro res = NULL; 10490a959df5SAl Viro return res; 10500a959df5SAl Viro } 10516d7b5aaeSAl Viro 1052f015f126SDavid Howells /* 1053f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1054f015f126SDavid Howells * 1055f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1056f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1057f015f126SDavid Howells * Up is towards /. 1058f015f126SDavid Howells * 1059f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1060f015f126SDavid Howells * root. 1061f015f126SDavid Howells */ 1062bab77ebfSAl Viro int follow_up(struct path *path) 10631da177e4SLinus Torvalds { 10640714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10650714a533SAl Viro struct mount *parent; 10661da177e4SLinus Torvalds struct dentry *mountpoint; 106799b7db7bSNick Piggin 106848a066e7SAl Viro read_seqlock_excl(&mount_lock); 10690714a533SAl Viro parent = mnt->mnt_parent; 10703c0a6163SAl Viro if (parent == mnt) { 107148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10721da177e4SLinus Torvalds return 0; 10731da177e4SLinus Torvalds } 10740714a533SAl Viro mntget(&parent->mnt); 1075a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1077bab77ebfSAl Viro dput(path->dentry); 1078bab77ebfSAl Viro path->dentry = mountpoint; 1079bab77ebfSAl Viro mntput(path->mnt); 10800714a533SAl Viro path->mnt = &parent->mnt; 10811da177e4SLinus Torvalds return 1; 10821da177e4SLinus Torvalds } 10834d359507SAl Viro EXPORT_SYMBOL(follow_up); 10841da177e4SLinus Torvalds 1085b5c84bf6SNick Piggin /* 10869875cf80SDavid Howells * Perform an automount 10879875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10889875cf80SDavid Howells * were called with. 10891da177e4SLinus Torvalds */ 1090756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10919875cf80SDavid Howells bool *need_mntput) 109231e6b01fSNick Piggin { 10939875cf80SDavid Howells struct vfsmount *mnt; 1094ea5b778aSDavid Howells int err; 10959875cf80SDavid Howells 10969875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10979875cf80SDavid Howells return -EREMOTE; 10989875cf80SDavid Howells 10990ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11000ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11010ec26fd0SMiklos Szeredi * the name. 11020ec26fd0SMiklos Szeredi * 11030ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11045a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11050ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11060ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11070ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11080ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11095a30d8a2SDavid Howells */ 1110756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1111d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11125a30d8a2SDavid Howells path->dentry->d_inode) 11139875cf80SDavid Howells return -EISDIR; 11140ec26fd0SMiklos Szeredi 1115756daf26SNeilBrown nd->total_link_count++; 1116756daf26SNeilBrown if (nd->total_link_count >= 40) 11179875cf80SDavid Howells return -ELOOP; 11189875cf80SDavid Howells 11199875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11209875cf80SDavid Howells if (IS_ERR(mnt)) { 11219875cf80SDavid Howells /* 11229875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11239875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11249875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11259875cf80SDavid Howells * 11269875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11279875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11289875cf80SDavid Howells * the path is inaccessible and we should say so. 11299875cf80SDavid Howells */ 1130756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11319875cf80SDavid Howells return -EREMOTE; 11329875cf80SDavid Howells return PTR_ERR(mnt); 113331e6b01fSNick Piggin } 1134ea5b778aSDavid Howells 11359875cf80SDavid Howells if (!mnt) /* mount collision */ 11369875cf80SDavid Howells return 0; 11379875cf80SDavid Howells 11388aef1884SAl Viro if (!*need_mntput) { 11398aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11408aef1884SAl Viro mntget(path->mnt); 11418aef1884SAl Viro *need_mntput = true; 11428aef1884SAl Viro } 114319a167afSAl Viro err = finish_automount(mnt, path); 1144ea5b778aSDavid Howells 1145ea5b778aSDavid Howells switch (err) { 1146ea5b778aSDavid Howells case -EBUSY: 1147ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114819a167afSAl Viro return 0; 1149ea5b778aSDavid Howells case 0: 11508aef1884SAl Viro path_put(path); 11519875cf80SDavid Howells path->mnt = mnt; 11529875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11539875cf80SDavid Howells return 0; 115419a167afSAl Viro default: 115519a167afSAl Viro return err; 11569875cf80SDavid Howells } 115719a167afSAl Viro 1158ea5b778aSDavid Howells } 11599875cf80SDavid Howells 11609875cf80SDavid Howells /* 11619875cf80SDavid Howells * Handle a dentry that is managed in some way. 1162cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11639875cf80SDavid Howells * - Flagged as mountpoint 11649875cf80SDavid Howells * - Flagged as automount point 11659875cf80SDavid Howells * 11669875cf80SDavid Howells * This may only be called in refwalk mode. 11679875cf80SDavid Howells * 11689875cf80SDavid Howells * Serialization is taken care of in namespace.c 11699875cf80SDavid Howells */ 1170756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11719875cf80SDavid Howells { 11728aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11739875cf80SDavid Howells unsigned managed; 11749875cf80SDavid Howells bool need_mntput = false; 11758aef1884SAl Viro int ret = 0; 11769875cf80SDavid Howells 11779875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11789875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11799875cf80SDavid Howells * the components of that value change under us */ 11809875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11819875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11829875cf80SDavid Howells unlikely(managed != 0)) { 1183cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1184cc53ce53SDavid Howells * being held. */ 1185cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1186cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1187cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11881aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1189cc53ce53SDavid Howells if (ret < 0) 11908aef1884SAl Viro break; 1191cc53ce53SDavid Howells } 1192cc53ce53SDavid Howells 11939875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11949875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11959875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11969875cf80SDavid Howells if (mounted) { 11979875cf80SDavid Howells dput(path->dentry); 11989875cf80SDavid Howells if (need_mntput) 1199463ffb2eSAl Viro mntput(path->mnt); 1200463ffb2eSAl Viro path->mnt = mounted; 1201463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12029875cf80SDavid Howells need_mntput = true; 12039875cf80SDavid Howells continue; 1204463ffb2eSAl Viro } 1205463ffb2eSAl Viro 12069875cf80SDavid Howells /* Something is mounted on this dentry in another 12079875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120848a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120948a066e7SAl Viro * get it */ 12101da177e4SLinus Torvalds } 12119875cf80SDavid Howells 12129875cf80SDavid Howells /* Handle an automount point */ 12139875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1214756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12159875cf80SDavid Howells if (ret < 0) 12168aef1884SAl Viro break; 12179875cf80SDavid Howells continue; 12189875cf80SDavid Howells } 12199875cf80SDavid Howells 12209875cf80SDavid Howells /* We didn't change the current path point */ 12219875cf80SDavid Howells break; 12229875cf80SDavid Howells } 12238aef1884SAl Viro 12248aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12258aef1884SAl Viro mntput(path->mnt); 1226e9742b53SAl Viro if (ret == -EISDIR || !ret) 1227e9742b53SAl Viro ret = 1; 12288402752eSAl Viro if (need_mntput) 12298402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12308402752eSAl Viro if (unlikely(ret < 0)) 12318402752eSAl Viro path_put_conditional(path, nd); 12328402752eSAl Viro return ret; 12331da177e4SLinus Torvalds } 12341da177e4SLinus Torvalds 1235cc53ce53SDavid Howells int follow_down_one(struct path *path) 12361da177e4SLinus Torvalds { 12371da177e4SLinus Torvalds struct vfsmount *mounted; 12381da177e4SLinus Torvalds 12391c755af4SAl Viro mounted = lookup_mnt(path); 12401da177e4SLinus Torvalds if (mounted) { 12419393bd07SAl Viro dput(path->dentry); 12429393bd07SAl Viro mntput(path->mnt); 12439393bd07SAl Viro path->mnt = mounted; 12449393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12451da177e4SLinus Torvalds return 1; 12461da177e4SLinus Torvalds } 12471da177e4SLinus Torvalds return 0; 12481da177e4SLinus Torvalds } 12494d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12501da177e4SLinus Torvalds 1251b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 125262a7375eSIan Kent { 1253b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1254b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 125562a7375eSIan Kent } 125662a7375eSIan Kent 12579875cf80SDavid Howells /* 1258287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1259287548e4SAl Viro * we meet a managed dentry that would need blocking. 12609875cf80SDavid Howells */ 12619875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1262254cf582SAl Viro struct inode **inode, unsigned *seqp) 12639875cf80SDavid Howells { 126462a7375eSIan Kent for (;;) { 1265c7105365SAl Viro struct mount *mounted; 126662a7375eSIan Kent /* 126762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126862a7375eSIan Kent * that wants to block transit. 126962a7375eSIan Kent */ 1270b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1271b8faf035SNeilBrown case -ECHILD: 1272b8faf035SNeilBrown default: 1273ab90911fSDavid Howells return false; 1274b8faf035SNeilBrown case -EISDIR: 1275b8faf035SNeilBrown return true; 1276b8faf035SNeilBrown case 0: 1277b8faf035SNeilBrown break; 1278b8faf035SNeilBrown } 127962a7375eSIan Kent 128062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1281b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 128262a7375eSIan Kent 1283474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12849875cf80SDavid Howells if (!mounted) 12859875cf80SDavid Howells break; 1286c7105365SAl Viro path->mnt = &mounted->mnt; 1287c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1288a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1289254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 129059430262SLinus Torvalds /* 129159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 129259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129359430262SLinus Torvalds * because a mount-point is always pinned. 129459430262SLinus Torvalds */ 129559430262SLinus Torvalds *inode = path->dentry->d_inode; 12969875cf80SDavid Howells } 1297f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1298b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1299287548e4SAl Viro } 1300287548e4SAl Viro 130131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 130231e6b01fSNick Piggin { 13034023bfc9SAl Viro struct inode *inode = nd->inode; 130431e6b01fSNick Piggin 130531e6b01fSNick Piggin while (1) { 1306aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130731e6b01fSNick Piggin break; 130831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 131031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 131131e6b01fSNick Piggin unsigned seq; 131231e6b01fSNick Piggin 13134023bfc9SAl Viro inode = parent->d_inode; 131431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1315aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1316aed434adSAl Viro return -ECHILD; 131731e6b01fSNick Piggin nd->path.dentry = parent; 131831e6b01fSNick Piggin nd->seq = seq; 1319397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1320397d425dSEric W. Biederman return -ENOENT; 132131e6b01fSNick Piggin break; 1322aed434adSAl Viro } else { 1323aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1324aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1325aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1326aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1327aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1328aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1329aed434adSAl Viro return -ECHILD; 1330aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 133131e6b01fSNick Piggin break; 1332aed434adSAl Viro /* we know that mountpoint was pinned */ 1333aed434adSAl Viro nd->path.dentry = mountpoint; 1334aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1335aed434adSAl Viro inode = inode2; 1336aed434adSAl Viro nd->seq = seq; 133731e6b01fSNick Piggin } 1338aed434adSAl Viro } 1339aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1340b37199e6SAl Viro struct mount *mounted; 1341b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1342aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1343aed434adSAl Viro return -ECHILD; 1344b37199e6SAl Viro if (!mounted) 1345b37199e6SAl Viro break; 1346b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1347b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13484023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1349b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1350b37199e6SAl Viro } 13514023bfc9SAl Viro nd->inode = inode; 135231e6b01fSNick Piggin return 0; 135331e6b01fSNick Piggin } 135431e6b01fSNick Piggin 13559875cf80SDavid Howells /* 1356cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1357cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1358cc53ce53SDavid Howells * caller is permitted to proceed or not. 1359cc53ce53SDavid Howells */ 13607cc90cc3SAl Viro int follow_down(struct path *path) 1361cc53ce53SDavid Howells { 1362cc53ce53SDavid Howells unsigned managed; 1363cc53ce53SDavid Howells int ret; 1364cc53ce53SDavid Howells 1365cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1366cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1367cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1368cc53ce53SDavid Howells * being held. 1369cc53ce53SDavid Howells * 1370cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1371cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1372cc53ce53SDavid Howells * other than its daemon the right to mount on its 1373cc53ce53SDavid Howells * superstructure. 1374cc53ce53SDavid Howells * 1375cc53ce53SDavid Howells * The filesystem may sleep at this point. 1376cc53ce53SDavid Howells */ 1377cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1378cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1379cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1380ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13811aed3e42SAl Viro path->dentry, false); 1382cc53ce53SDavid Howells if (ret < 0) 1383cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1384cc53ce53SDavid Howells } 1385cc53ce53SDavid Howells 1386cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1387cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1388cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1389cc53ce53SDavid Howells if (!mounted) 1390cc53ce53SDavid Howells break; 1391cc53ce53SDavid Howells dput(path->dentry); 1392cc53ce53SDavid Howells mntput(path->mnt); 1393cc53ce53SDavid Howells path->mnt = mounted; 1394cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1395cc53ce53SDavid Howells continue; 1396cc53ce53SDavid Howells } 1397cc53ce53SDavid Howells 1398cc53ce53SDavid Howells /* Don't handle automount points here */ 1399cc53ce53SDavid Howells break; 1400cc53ce53SDavid Howells } 1401cc53ce53SDavid Howells return 0; 1402cc53ce53SDavid Howells } 14034d359507SAl Viro EXPORT_SYMBOL(follow_down); 1404cc53ce53SDavid Howells 1405cc53ce53SDavid Howells /* 14069875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14079875cf80SDavid Howells */ 14089875cf80SDavid Howells static void follow_mount(struct path *path) 14099875cf80SDavid Howells { 14109875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14119875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14129875cf80SDavid Howells if (!mounted) 14139875cf80SDavid Howells break; 14149875cf80SDavid Howells dput(path->dentry); 14159875cf80SDavid Howells mntput(path->mnt); 14169875cf80SDavid Howells path->mnt = mounted; 14179875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14189875cf80SDavid Howells } 14199875cf80SDavid Howells } 14209875cf80SDavid Howells 1421eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1422eedf265aSEric W. Biederman { 1423eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1424eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1425eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1426eedf265aSEric W. Biederman dput(old); 1427eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1428eedf265aSEric W. Biederman return -ENOENT; 1429eedf265aSEric W. Biederman return 0; 1430eedf265aSEric W. Biederman } 1431eedf265aSEric W. Biederman 1432397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14331da177e4SLinus Torvalds { 14341da177e4SLinus Torvalds while(1) { 14352a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14362a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14371da177e4SLinus Torvalds break; 14381da177e4SLinus Torvalds } 14394ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1440eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1441eedf265aSEric W. Biederman if (ret) 1442eedf265aSEric W. Biederman return ret; 14431da177e4SLinus Torvalds break; 14441da177e4SLinus Torvalds } 14453088dd70SAl Viro if (!follow_up(&nd->path)) 14461da177e4SLinus Torvalds break; 14471da177e4SLinus Torvalds } 144879ed0226SAl Viro follow_mount(&nd->path); 144931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1450397d425dSEric W. Biederman return 0; 14511da177e4SLinus Torvalds } 14521da177e4SLinus Torvalds 14531da177e4SLinus Torvalds /* 1454bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1455bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1456bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1457baa03890SNick Piggin */ 1458e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1459e3c13928SAl Viro struct dentry *dir, 14606c51e513SAl Viro unsigned int flags) 1461baa03890SNick Piggin { 1462baa03890SNick Piggin struct dentry *dentry; 1463bad61189SMiklos Szeredi int error; 1464baa03890SNick Piggin 1465bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1466bad61189SMiklos Szeredi if (dentry) { 146739e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1468201f956eSAl Viro error = d_revalidate(dentry, flags); 1469bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 147074ff0ffcSAl Viro if (!error) 14715542aa2fSEric W. Biederman d_invalidate(dentry); 1472bad61189SMiklos Szeredi dput(dentry); 147374ff0ffcSAl Viro return ERR_PTR(error); 1474bad61189SMiklos Szeredi } 1475bad61189SMiklos Szeredi } 1476bad61189SMiklos Szeredi } 1477baa03890SNick Piggin return dentry; 1478baa03890SNick Piggin } 1479baa03890SNick Piggin 1480baa03890SNick Piggin /* 148113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 148213a2c3beSJ. Bruce Fields * unhashed. 1483bad61189SMiklos Szeredi * 1484bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 148544396f4bSJosef Bacik */ 1486bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 148772bd866aSAl Viro unsigned int flags) 148844396f4bSJosef Bacik { 148944396f4bSJosef Bacik struct dentry *old; 149044396f4bSJosef Bacik 149144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1492bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1493e188dc02SMiklos Szeredi dput(dentry); 149444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1495e188dc02SMiklos Szeredi } 149644396f4bSJosef Bacik 149772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 149844396f4bSJosef Bacik if (unlikely(old)) { 149944396f4bSJosef Bacik dput(dentry); 150044396f4bSJosef Bacik dentry = old; 150144396f4bSJosef Bacik } 150244396f4bSJosef Bacik return dentry; 150344396f4bSJosef Bacik } 150444396f4bSJosef Bacik 1505e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 150672bd866aSAl Viro struct dentry *base, unsigned int flags) 1507a3255546SAl Viro { 15086c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1509a3255546SAl Viro 15106c51e513SAl Viro if (dentry) 1511a3255546SAl Viro return dentry; 1512bad61189SMiklos Szeredi 15136c51e513SAl Viro dentry = d_alloc(base, name); 15146c51e513SAl Viro if (unlikely(!dentry)) 15156c51e513SAl Viro return ERR_PTR(-ENOMEM); 15166c51e513SAl Viro 151772bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1518a3255546SAl Viro } 1519a3255546SAl Viro 1520e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1521254cf582SAl Viro struct path *path, struct inode **inode, 1522254cf582SAl Viro unsigned *seqp) 15231da177e4SLinus Torvalds { 15244ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 152531e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15265a18fff2SAl Viro int status = 1; 15279875cf80SDavid Howells int err; 15289875cf80SDavid Howells 15293cac260aSAl Viro /* 1530b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15315d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15325d0f49c1SAl Viro * going to fall back to non-racy lookup. 1533b04f784eSNick Piggin */ 153431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 153531e6b01fSNick Piggin unsigned seq; 1536766c4cbfSAl Viro bool negative; 1537da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15385d0f49c1SAl Viro if (unlikely(!dentry)) { 15395d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15405d0f49c1SAl Viro return -ECHILD; 1541e9742b53SAl Viro return 0; 15425d0f49c1SAl Viro } 15435a18fff2SAl Viro 154412f8ad4bSLinus Torvalds /* 154512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 154612f8ad4bSLinus Torvalds * the dentry name information from lookup. 154712f8ad4bSLinus Torvalds */ 154863afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1549766c4cbfSAl Viro negative = d_is_negative(dentry); 15505d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 155112f8ad4bSLinus Torvalds return -ECHILD; 155212f8ad4bSLinus Torvalds 155312f8ad4bSLinus Torvalds /* 155412f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 155512f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 155612f8ad4bSLinus Torvalds * 155712f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 155812f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 155912f8ad4bSLinus Torvalds */ 15605d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 156131e6b01fSNick Piggin return -ECHILD; 15625a18fff2SAl Viro 1563254cf582SAl Viro *seqp = seq; 15645d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15654ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15665a18fff2SAl Viro if (unlikely(status <= 0)) { 15675d0f49c1SAl Viro if (unlazy_walk(nd, dentry, seq)) 15685d0f49c1SAl Viro return -ECHILD; 15695d0f49c1SAl Viro if (status == -ECHILD) 15705d0f49c1SAl Viro status = d_revalidate(dentry, nd->flags); 15715d0f49c1SAl Viro } else { 1572daf3761cSTrond Myklebust /* 1573daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1574daf3761cSTrond Myklebust * case that drops it. 1575daf3761cSTrond Myklebust */ 15765d0f49c1SAl Viro if (unlikely(negative)) 1577daf3761cSTrond Myklebust return -ENOENT; 157831e6b01fSNick Piggin path->mnt = mnt; 157931e6b01fSNick Piggin path->dentry = dentry; 1580254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1581e9742b53SAl Viro return 1; 1582254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15835a18fff2SAl Viro return -ECHILD; 15845d0f49c1SAl Viro } 15855a18fff2SAl Viro } else { 1586e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 158781e6f520SAl Viro if (unlikely(!dentry)) 1588e9742b53SAl Viro return 0; 15895d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15904ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15915d0f49c1SAl Viro } 15925a18fff2SAl Viro if (unlikely(status <= 0)) { 1593e9742b53SAl Viro if (!status) 15945d0f49c1SAl Viro d_invalidate(dentry); 15955a18fff2SAl Viro dput(dentry); 15965a18fff2SAl Viro return status; 15975a18fff2SAl Viro } 1598766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1599766c4cbfSAl Viro dput(dentry); 1600766c4cbfSAl Viro return -ENOENT; 1601766c4cbfSAl Viro } 16025d0f49c1SAl Viro 16031da177e4SLinus Torvalds path->mnt = mnt; 16041da177e4SLinus Torvalds path->dentry = dentry; 1605756daf26SNeilBrown err = follow_managed(path, nd); 1606e9742b53SAl Viro if (likely(err > 0)) 160763afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16088402752eSAl Viro return err; 1609697f514dSMiklos Szeredi } 1610697f514dSMiklos Szeredi 1611697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1612e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1613e3c13928SAl Viro struct dentry *dir, 1614e3c13928SAl Viro unsigned int flags) 1615697f514dSMiklos Szeredi { 161694bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16171936386eSAl Viro struct inode *inode = dir->d_inode; 1618d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16191936386eSAl Viro 16209902af79SAl Viro inode_lock_shared(inode); 16211936386eSAl Viro /* Don't go there if it's already dead */ 162294bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 162394bdd655SAl Viro goto out; 162494bdd655SAl Viro again: 1625d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 162694bdd655SAl Viro if (IS_ERR(dentry)) 162794bdd655SAl Viro goto out; 162894bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1629949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1630949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1631949a852eSAl Viro int error = d_revalidate(dentry, flags); 1632949a852eSAl Viro if (unlikely(error <= 0)) { 163394bdd655SAl Viro if (!error) { 1634949a852eSAl Viro d_invalidate(dentry); 1635949a852eSAl Viro dput(dentry); 163694bdd655SAl Viro goto again; 163794bdd655SAl Viro } 163894bdd655SAl Viro dput(dentry); 1639949a852eSAl Viro dentry = ERR_PTR(error); 1640949a852eSAl Viro } 1641949a852eSAl Viro } 164294bdd655SAl Viro } else { 16431936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 164485c7f810SAl Viro d_lookup_done(dentry); 16451936386eSAl Viro if (unlikely(old)) { 16461936386eSAl Viro dput(dentry); 16471936386eSAl Viro dentry = old; 1648949a852eSAl Viro } 1649949a852eSAl Viro } 165094bdd655SAl Viro out: 16519902af79SAl Viro inode_unlock_shared(inode); 1652e3c13928SAl Viro return dentry; 16531da177e4SLinus Torvalds } 16541da177e4SLinus Torvalds 165552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 165652094c8aSAl Viro { 165752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16584ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 165952094c8aSAl Viro if (err != -ECHILD) 166052094c8aSAl Viro return err; 16616e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 166252094c8aSAl Viro return -ECHILD; 166352094c8aSAl Viro } 16644ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 166552094c8aSAl Viro } 166652094c8aSAl Viro 16679856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16689856fa1bSAl Viro { 16699856fa1bSAl Viro if (type == LAST_DOTDOT) { 16709e6697e2SAl Viro if (!nd->root.mnt) 16719e6697e2SAl Viro set_root(nd); 16729856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 167370291aecSAl Viro return follow_dotdot_rcu(nd); 16749856fa1bSAl Viro } else 1675397d425dSEric W. Biederman return follow_dotdot(nd); 16769856fa1bSAl Viro } 16779856fa1bSAl Viro return 0; 16789856fa1bSAl Viro } 16799856fa1bSAl Viro 1680181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1681181548c0SAl Viro struct inode *inode, unsigned seq) 1682d63ff28fSAl Viro { 1683626de996SAl Viro int error; 16841cf2665bSAl Viro struct saved *last; 1685756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1686626de996SAl Viro path_to_nameidata(link, nd); 1687626de996SAl Viro return -ELOOP; 1688626de996SAl Viro } 1689bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1690cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1691cd179f44SAl Viro mntget(link->mnt); 16927973387aSAl Viro } 1693626de996SAl Viro error = nd_alloc_stack(nd); 1694626de996SAl Viro if (unlikely(error)) { 1695bc40aee0SAl Viro if (error == -ECHILD) { 1696bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1697bc40aee0SAl Viro return -ECHILD; 1698bc40aee0SAl Viro error = nd_alloc_stack(nd); 1699bc40aee0SAl Viro } 1700bc40aee0SAl Viro if (error) { 1701cd179f44SAl Viro path_put(link); 1702626de996SAl Viro return error; 1703626de996SAl Viro } 1704bc40aee0SAl Viro } 1705626de996SAl Viro 1706ab104923SAl Viro last = nd->stack + nd->depth++; 17071cf2665bSAl Viro last->link = *link; 1708fceef393SAl Viro clear_delayed_call(&last->done); 1709fceef393SAl Viro nd->link_inode = inode; 17100450b2d1SAl Viro last->seq = seq; 1711d63ff28fSAl Viro return 1; 1712d63ff28fSAl Viro } 1713d63ff28fSAl Viro 17143ddcd056SLinus Torvalds /* 17153ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17163ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17173ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17183ddcd056SLinus Torvalds * for the common case. 17193ddcd056SLinus Torvalds */ 1720254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1721181548c0SAl Viro int follow, 1722181548c0SAl Viro struct inode *inode, unsigned seq) 17233ddcd056SLinus Torvalds { 1724d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1725d63ff28fSAl Viro return 0; 1726d63ff28fSAl Viro if (!follow) 1727d63ff28fSAl Viro return 0; 1728a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1729a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1730a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1731a7f77542SAl Viro return -ECHILD; 1732a7f77542SAl Viro } 1733181548c0SAl Viro return pick_link(nd, link, inode, seq); 17343ddcd056SLinus Torvalds } 17353ddcd056SLinus Torvalds 17364693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17374693a547SAl Viro 17384693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1739ce57dfc1SAl Viro { 1740caa85634SAl Viro struct path path; 1741ce57dfc1SAl Viro struct inode *inode; 1742254cf582SAl Viro unsigned seq; 1743ce57dfc1SAl Viro int err; 1744ce57dfc1SAl Viro /* 1745ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1746ce57dfc1SAl Viro * to be able to know about the current root directory and 1747ce57dfc1SAl Viro * parent relationships. 1748ce57dfc1SAl Viro */ 17494693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17504693a547SAl Viro err = handle_dots(nd, nd->last_type); 17514693a547SAl Viro if (flags & WALK_PUT) 17524693a547SAl Viro put_link(nd); 17534693a547SAl Viro return err; 17544693a547SAl Viro } 1755254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1756e9742b53SAl Viro if (unlikely(err <= 0)) { 1757697f514dSMiklos Szeredi if (err < 0) 1758f0a9ba70SAl Viro return err; 1759e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1760e3c13928SAl Viro nd->flags); 1761e3c13928SAl Viro if (IS_ERR(path.dentry)) 1762e3c13928SAl Viro return PTR_ERR(path.dentry); 17637500c38aSAl Viro 1764e3c13928SAl Viro path.mnt = nd->path.mnt; 1765e3c13928SAl Viro err = follow_managed(&path, nd); 1766e3c13928SAl Viro if (unlikely(err < 0)) 1767f0a9ba70SAl Viro return err; 1768697f514dSMiklos Szeredi 17697500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17707500c38aSAl Viro path_to_nameidata(&path, nd); 17717500c38aSAl Viro return -ENOENT; 17727500c38aSAl Viro } 17737500c38aSAl Viro 1774254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1775d4565649SAl Viro inode = d_backing_inode(path.dentry); 1776766c4cbfSAl Viro } 1777697f514dSMiklos Szeredi 17784693a547SAl Viro if (flags & WALK_PUT) 17794693a547SAl Viro put_link(nd); 1780181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1781d63ff28fSAl Viro if (unlikely(err)) 1782d63ff28fSAl Viro return err; 1783caa85634SAl Viro path_to_nameidata(&path, nd); 1784ce57dfc1SAl Viro nd->inode = inode; 1785254cf582SAl Viro nd->seq = seq; 1786ce57dfc1SAl Viro return 0; 1787ce57dfc1SAl Viro } 1788ce57dfc1SAl Viro 17891da177e4SLinus Torvalds /* 1790bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1791bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1792bfcfaa77SLinus Torvalds * 1793bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1794bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1795bfcfaa77SLinus Torvalds * fast. 1796bfcfaa77SLinus Torvalds * 1797bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1798bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1799bfcfaa77SLinus Torvalds * crossing operation. 1800bfcfaa77SLinus Torvalds * 1801bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1802bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1803bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1804bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1805bfcfaa77SLinus Torvalds */ 1806bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1807bfcfaa77SLinus Torvalds 1808f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1809bfcfaa77SLinus Torvalds 1810468a9428SGeorge Spelvin #ifdef HASH_MIX 1811bfcfaa77SLinus Torvalds 1812468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1813468a9428SGeorge Spelvin 1814468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18152a18da7aSGeorge Spelvin /* 18162a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18172a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18182a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18192a18da7aSGeorge Spelvin * and no temporaries. 18202a18da7aSGeorge Spelvin * 18212a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18222a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18232a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18242a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18252a18da7aSGeorge Spelvin * 18262a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18272a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18282a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18292a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18302a18da7aSGeorge Spelvin * 18312a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18322a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18332a18da7aSGeorge Spelvin * toggling any given output bit. 18342a18da7aSGeorge Spelvin * 18352a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18362a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18372a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18382a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18392a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18402a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18412a18da7aSGeorge Spelvin * Perfect: 8192 258048 18422a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18432a18da7aSGeorge Spelvin */ 18442a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18452a18da7aSGeorge Spelvin ( x ^= (a), \ 18462a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18472a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18482a18da7aSGeorge Spelvin y *= 9 ) 1849bfcfaa77SLinus Torvalds 18500fed3ac8SGeorge Spelvin /* 18512a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18522a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18532a18da7aSGeorge Spelvin * work done before the hash value is used. 18540fed3ac8SGeorge Spelvin */ 18552a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18560fed3ac8SGeorge Spelvin { 18572a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18582a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18592a18da7aSGeorge Spelvin return y >> 32; 18600fed3ac8SGeorge Spelvin } 18610fed3ac8SGeorge Spelvin 1862bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1863bfcfaa77SLinus Torvalds 18642a18da7aSGeorge Spelvin /* 18652a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18662a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18672a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18682a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18692a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18702a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18712a18da7aSGeorge Spelvin * Perfect: 2048 31744 18722a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18732a18da7aSGeorge Spelvin */ 18742a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18752a18da7aSGeorge Spelvin ( x ^= (a), \ 18762a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18772a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18782a18da7aSGeorge Spelvin y *= 9 ) 1879bfcfaa77SLinus Torvalds 18802a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18810fed3ac8SGeorge Spelvin { 18822a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18832a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18840fed3ac8SGeorge Spelvin } 18850fed3ac8SGeorge Spelvin 1886bfcfaa77SLinus Torvalds #endif 1887bfcfaa77SLinus Torvalds 18882a18da7aSGeorge Spelvin /* 18892a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18902a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18912a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18922a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18932a18da7aSGeorge Spelvin * finds the delimiter after the name. 18942a18da7aSGeorge Spelvin */ 1895fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 1896bfcfaa77SLinus Torvalds { 18972a18da7aSGeorge Spelvin unsigned long a, x = 0, y = 0; 1898bfcfaa77SLinus Torvalds 1899bfcfaa77SLinus Torvalds for (;;) { 1900fcfd2fbfSGeorge Spelvin if (!len) 1901fcfd2fbfSGeorge Spelvin goto done; 1902e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1903bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1904bfcfaa77SLinus Torvalds break; 19052a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1906bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1907bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1908bfcfaa77SLinus Torvalds } 19092a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1910bfcfaa77SLinus Torvalds done: 19112a18da7aSGeorge Spelvin return fold_hash(x, y); 1912bfcfaa77SLinus Torvalds } 1913bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1914bfcfaa77SLinus Torvalds 1915fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1916fcfd2fbfSGeorge Spelvin u64 hashlen_string(const char *name) 1917fcfd2fbfSGeorge Spelvin { 19182a18da7aSGeorge Spelvin unsigned long a = 0, x = 0, y = 0, adata, mask, len; 1919fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1920fcfd2fbfSGeorge Spelvin 1921fcfd2fbfSGeorge Spelvin len = -sizeof(unsigned long); 1922fcfd2fbfSGeorge Spelvin do { 19232a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1924fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 1925fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1926fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1927fcfd2fbfSGeorge Spelvin 1928fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1929fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19302a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1931fcfd2fbfSGeorge Spelvin 19322a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1933fcfd2fbfSGeorge Spelvin } 1934fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1935fcfd2fbfSGeorge Spelvin 1936bfcfaa77SLinus Torvalds /* 1937bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1938d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1939bfcfaa77SLinus Torvalds */ 1940d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1941bfcfaa77SLinus Torvalds { 19422a18da7aSGeorge Spelvin unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len; 194336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1944bfcfaa77SLinus Torvalds 1945bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1946bfcfaa77SLinus Torvalds do { 19472a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1948bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1949e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 195036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 195136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1952bfcfaa77SLinus Torvalds 195336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 195436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 195536126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19562a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 195736126f8fSLinus Torvalds 19582a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1959bfcfaa77SLinus Torvalds } 1960bfcfaa77SLinus Torvalds 19612a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1962bfcfaa77SLinus Torvalds 1963fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 1964fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 19650145acc2SLinus Torvalds { 19660145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 19670145acc2SLinus Torvalds while (len--) 1968fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19690145acc2SLinus Torvalds return end_name_hash(hash); 19700145acc2SLinus Torvalds } 1971ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19720145acc2SLinus Torvalds 1973fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1974f2a031b6SGeorge Spelvin u64 hashlen_string(const char *name) 1975fcfd2fbfSGeorge Spelvin { 1976fcfd2fbfSGeorge Spelvin unsigned long hash = init_name_hash(); 1977fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1978fcfd2fbfSGeorge Spelvin 1979fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1980e0ab7af9SGeorge Spelvin while (c) { 1981fcfd2fbfSGeorge Spelvin len++; 1982fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1983fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1984e0ab7af9SGeorge Spelvin } 1985fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1986fcfd2fbfSGeorge Spelvin } 1987f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1988fcfd2fbfSGeorge Spelvin 19893ddcd056SLinus Torvalds /* 1990200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1991200e9ef7SLinus Torvalds * one character. 1992200e9ef7SLinus Torvalds */ 1993d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1994200e9ef7SLinus Torvalds { 1995200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1996200e9ef7SLinus Torvalds unsigned long len = 0, c; 1997200e9ef7SLinus Torvalds 1998200e9ef7SLinus Torvalds c = (unsigned char)*name; 1999200e9ef7SLinus Torvalds do { 2000200e9ef7SLinus Torvalds len++; 2001200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2002200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2003200e9ef7SLinus Torvalds } while (c && c != '/'); 2004d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2005200e9ef7SLinus Torvalds } 2006200e9ef7SLinus Torvalds 2007bfcfaa77SLinus Torvalds #endif 2008bfcfaa77SLinus Torvalds 2009200e9ef7SLinus Torvalds /* 20101da177e4SLinus Torvalds * Name resolution. 2011ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2012ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20131da177e4SLinus Torvalds * 2014ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2015ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20161da177e4SLinus Torvalds */ 20176de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20181da177e4SLinus Torvalds { 20191da177e4SLinus Torvalds int err; 20201da177e4SLinus Torvalds 20211da177e4SLinus Torvalds while (*name=='/') 20221da177e4SLinus Torvalds name++; 20231da177e4SLinus Torvalds if (!*name) 20249e18f10aSAl Viro return 0; 20251da177e4SLinus Torvalds 20261da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20271da177e4SLinus Torvalds for(;;) { 2028d6bb3e90SLinus Torvalds u64 hash_len; 2029fe479a58SAl Viro int type; 20301da177e4SLinus Torvalds 203152094c8aSAl Viro err = may_lookup(nd); 20321da177e4SLinus Torvalds if (err) 20333595e234SAl Viro return err; 20341da177e4SLinus Torvalds 2035d6bb3e90SLinus Torvalds hash_len = hash_name(name); 20361da177e4SLinus Torvalds 2037fe479a58SAl Viro type = LAST_NORM; 2038d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2039fe479a58SAl Viro case 2: 2040200e9ef7SLinus Torvalds if (name[1] == '.') { 2041fe479a58SAl Viro type = LAST_DOTDOT; 204216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 204316c2cd71SAl Viro } 2044fe479a58SAl Viro break; 2045fe479a58SAl Viro case 1: 2046fe479a58SAl Viro type = LAST_DOT; 2047fe479a58SAl Viro } 20485a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20495a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 205016c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20515a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2052a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2053da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20545a202bcdSAl Viro if (err < 0) 20553595e234SAl Viro return err; 2056d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2057d6bb3e90SLinus Torvalds name = this.name; 20585a202bcdSAl Viro } 20595a202bcdSAl Viro } 2060fe479a58SAl Viro 2061d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2062d6bb3e90SLinus Torvalds nd->last.name = name; 20635f4a6a69SAl Viro nd->last_type = type; 20645f4a6a69SAl Viro 2065d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2066d6bb3e90SLinus Torvalds if (!*name) 2067bdf6cbf1SAl Viro goto OK; 2068200e9ef7SLinus Torvalds /* 2069200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2070200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2071200e9ef7SLinus Torvalds */ 2072200e9ef7SLinus Torvalds do { 2073d6bb3e90SLinus Torvalds name++; 2074d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20758620c238SAl Viro if (unlikely(!*name)) { 20768620c238SAl Viro OK: 2077368ee9baSAl Viro /* pathname body, done */ 20788620c238SAl Viro if (!nd->depth) 20798620c238SAl Viro return 0; 20808620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2081368ee9baSAl Viro /* trailing symlink, done */ 20828620c238SAl Viro if (!name) 20838620c238SAl Viro return 0; 20848620c238SAl Viro /* last component of nested symlink */ 20854693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 20868620c238SAl Viro } else { 20874693a547SAl Viro err = walk_component(nd, WALK_GET); 20888620c238SAl Viro } 2089ce57dfc1SAl Viro if (err < 0) 20903595e234SAl Viro return err; 2091fe479a58SAl Viro 2092ce57dfc1SAl Viro if (err) { 2093626de996SAl Viro const char *s = get_link(nd); 20945a460275SAl Viro 2095a1c83681SViresh Kumar if (IS_ERR(s)) 20963595e234SAl Viro return PTR_ERR(s); 2097172a39a0SAl Viro err = 0; 209812b09578SAl Viro if (unlikely(!s)) { 209912b09578SAl Viro /* jumped */ 2100b9ff4429SAl Viro put_link(nd); 210112b09578SAl Viro } else { 2102071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 210332cd7468SAl Viro name = s; 21049e18f10aSAl Viro continue; 210548c8b0c5SAl Viro } 210631e6b01fSNick Piggin } 210797242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 210897242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 210997242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 211097242f99SAl Viro return -ECHILD; 211197242f99SAl Viro } 21123595e234SAl Viro return -ENOTDIR; 21135f4a6a69SAl Viro } 2114ce57dfc1SAl Viro } 211597242f99SAl Viro } 21161da177e4SLinus Torvalds 2117c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 211831e6b01fSNick Piggin { 211931e6b01fSNick Piggin int retval = 0; 2120c8a53ee5SAl Viro const char *s = nd->name->name; 212131e6b01fSNick Piggin 212231e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2123980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 212431e6b01fSNick Piggin nd->depth = 0; 21255b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2126b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2127b18825a7SDavid Howells struct inode *inode = root->d_inode; 2128fd2f7cb5SAl Viro if (*s) { 212944b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2130368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21315b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21325b6ca027SAl Viro if (retval) 2133368ee9baSAl Viro return ERR_PTR(retval); 213473d049a4SAl Viro } 21355b6ca027SAl Viro nd->path = nd->root; 21365b6ca027SAl Viro nd->inode = inode; 21375b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21388b61e74fSAl Viro rcu_read_lock(); 21395b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21408f47a016SAl Viro nd->root_seq = nd->seq; 214148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21425b6ca027SAl Viro } else { 21435b6ca027SAl Viro path_get(&nd->path); 21445b6ca027SAl Viro } 2145368ee9baSAl Viro return s; 21465b6ca027SAl Viro } 21475b6ca027SAl Viro 214831e6b01fSNick Piggin nd->root.mnt = NULL; 2149248fb5b9SAl Viro nd->path.mnt = NULL; 2150248fb5b9SAl Viro nd->path.dentry = NULL; 215131e6b01fSNick Piggin 215248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2153fd2f7cb5SAl Viro if (*s == '/') { 21549e6697e2SAl Viro if (flags & LOOKUP_RCU) 21558b61e74fSAl Viro rcu_read_lock(); 2156e41f7d4eSAl Viro set_root(nd); 2157248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2158ef55d917SAl Viro return s; 2159ef55d917SAl Viro nd->root.mnt = NULL; 2160ef55d917SAl Viro rcu_read_unlock(); 2161ef55d917SAl Viro return ERR_PTR(-ECHILD); 2162c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2163e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 216431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2165c28cc364SNick Piggin unsigned seq; 216631e6b01fSNick Piggin 21678b61e74fSAl Viro rcu_read_lock(); 216831e6b01fSNick Piggin 2169c28cc364SNick Piggin do { 2170c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 217131e6b01fSNick Piggin nd->path = fs->pwd; 2172ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2173c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2174c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2175e41f7d4eSAl Viro } else { 2176e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2177ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2178e41f7d4eSAl Viro } 2179ef55d917SAl Viro return s; 218031e6b01fSNick Piggin } else { 2181582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2182c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 218331e6b01fSNick Piggin struct dentry *dentry; 218431e6b01fSNick Piggin 21852903ff01SAl Viro if (!f.file) 2186368ee9baSAl Viro return ERR_PTR(-EBADF); 218731e6b01fSNick Piggin 21882903ff01SAl Viro dentry = f.file->f_path.dentry; 218931e6b01fSNick Piggin 2190fd2f7cb5SAl Viro if (*s) { 219144b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21922903ff01SAl Viro fdput(f); 2193368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2194f52e0c11SAl Viro } 21952903ff01SAl Viro } 21962903ff01SAl Viro 21972903ff01SAl Viro nd->path = f.file->f_path; 2198e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 21998b61e74fSAl Viro rcu_read_lock(); 220034a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 220134a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22025590ff0dSUlrich Drepper } else { 22032903ff01SAl Viro path_get(&nd->path); 220434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22051da177e4SLinus Torvalds } 220634a26b99SAl Viro fdput(f); 2207368ee9baSAl Viro return s; 2208e41f7d4eSAl Viro } 22099b4a9b14SAl Viro } 22109b4a9b14SAl Viro 22113bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 221295fa25d9SAl Viro { 221395fa25d9SAl Viro const char *s; 2214fec2fa24SAl Viro int error = may_follow_link(nd); 2215deb106c6SAl Viro if (unlikely(error)) 22163bdba28bSAl Viro return ERR_PTR(error); 221795fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2218fab51e8aSAl Viro nd->stack[0].name = NULL; 22193b2e7f75SAl Viro s = get_link(nd); 2220deb106c6SAl Viro return s ? s : ""; 222195fa25d9SAl Viro } 222295fa25d9SAl Viro 2223caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2224bd92d7feSAl Viro { 2225bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2226bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2227bd92d7feSAl Viro 2228bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2229deb106c6SAl Viro return walk_component(nd, 22304693a547SAl Viro nd->flags & LOOKUP_FOLLOW 22314693a547SAl Viro ? nd->depth 22324693a547SAl Viro ? WALK_PUT | WALK_GET 22334693a547SAl Viro : WALK_GET 22344693a547SAl Viro : 0); 2235bd92d7feSAl Viro } 2236bd92d7feSAl Viro 22379b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2238c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22399b4a9b14SAl Viro { 2240c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2241bd92d7feSAl Viro int err; 224231e6b01fSNick Piggin 2243368ee9baSAl Viro if (IS_ERR(s)) 2244368ee9baSAl Viro return PTR_ERR(s); 22453bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22463bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22473bdba28bSAl Viro s = trailing_symlink(nd); 22483bdba28bSAl Viro if (IS_ERR(s)) { 22493bdba28bSAl Viro err = PTR_ERR(s); 22506d7b5aaeSAl Viro break; 2251bd92d7feSAl Viro } 2252bd92d7feSAl Viro } 22539f1fafeeSAl Viro if (!err) 22549f1fafeeSAl Viro err = complete_walk(nd); 2255bd92d7feSAl Viro 2256deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2257deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2258bd23a539SAl Viro err = -ENOTDIR; 2259625b6d10SAl Viro if (!err) { 2260625b6d10SAl Viro *path = nd->path; 2261625b6d10SAl Viro nd->path.mnt = NULL; 2262625b6d10SAl Viro nd->path.dentry = NULL; 2263625b6d10SAl Viro } 2264deb106c6SAl Viro terminate_walk(nd); 2265bd92d7feSAl Viro return err; 226631e6b01fSNick Piggin } 226731e6b01fSNick Piggin 2268625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22699ad1aaa6SAl Viro struct path *path, struct path *root) 2270873f1eedSJeff Layton { 2271894bc8c4SAl Viro int retval; 22729883d185SAl Viro struct nameidata nd; 2273abc9f5beSAl Viro if (IS_ERR(name)) 2274abc9f5beSAl Viro return PTR_ERR(name); 22759ad1aaa6SAl Viro if (unlikely(root)) { 22769ad1aaa6SAl Viro nd.root = *root; 22779ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22789ad1aaa6SAl Viro } 22799883d185SAl Viro set_nameidata(&nd, dfd, name); 2280c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2281873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2282c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2283873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2284c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2285873f1eedSJeff Layton 2286873f1eedSJeff Layton if (likely(!retval)) 2287625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 22889883d185SAl Viro restore_nameidata(); 2289e4bd1c1aSAl Viro putname(name); 2290873f1eedSJeff Layton return retval; 2291873f1eedSJeff Layton } 2292873f1eedSJeff Layton 22938bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2294c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2295391172c4SAl Viro struct path *parent) 22968bcb77faSAl Viro { 2297c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2298368ee9baSAl Viro int err; 2299368ee9baSAl Viro if (IS_ERR(s)) 2300368ee9baSAl Viro return PTR_ERR(s); 2301368ee9baSAl Viro err = link_path_walk(s, nd); 23028bcb77faSAl Viro if (!err) 23038bcb77faSAl Viro err = complete_walk(nd); 2304391172c4SAl Viro if (!err) { 2305391172c4SAl Viro *parent = nd->path; 2306391172c4SAl Viro nd->path.mnt = NULL; 2307391172c4SAl Viro nd->path.dentry = NULL; 2308391172c4SAl Viro } 2309deb106c6SAl Viro terminate_walk(nd); 23108bcb77faSAl Viro return err; 23118bcb77faSAl Viro } 23128bcb77faSAl Viro 23135c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2314391172c4SAl Viro unsigned int flags, struct path *parent, 2315391172c4SAl Viro struct qstr *last, int *type) 23168bcb77faSAl Viro { 23178bcb77faSAl Viro int retval; 23189883d185SAl Viro struct nameidata nd; 23198bcb77faSAl Viro 23205c31b6ceSAl Viro if (IS_ERR(name)) 23215c31b6ceSAl Viro return name; 23229883d185SAl Viro set_nameidata(&nd, dfd, name); 2323c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23248bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2325c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23268bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2327c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2328391172c4SAl Viro if (likely(!retval)) { 2329391172c4SAl Viro *last = nd.last; 2330391172c4SAl Viro *type = nd.last_type; 2331391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23325c31b6ceSAl Viro } else { 23335c31b6ceSAl Viro putname(name); 23345c31b6ceSAl Viro name = ERR_PTR(retval); 2335391172c4SAl Viro } 23369883d185SAl Viro restore_nameidata(); 23375c31b6ceSAl Viro return name; 23388bcb77faSAl Viro } 23398bcb77faSAl Viro 234079714f72SAl Viro /* does lookup, returns the object with parent locked */ 234179714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23425590ff0dSUlrich Drepper { 23435c31b6ceSAl Viro struct filename *filename; 23445c31b6ceSAl Viro struct dentry *d; 2345391172c4SAl Viro struct qstr last; 2346391172c4SAl Viro int type; 234751689104SPaul Moore 23485c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23495c31b6ceSAl Viro &last, &type); 235051689104SPaul Moore if (IS_ERR(filename)) 235151689104SPaul Moore return ERR_CAST(filename); 23525c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2353391172c4SAl Viro path_put(path); 23545c31b6ceSAl Viro putname(filename); 23555c31b6ceSAl Viro return ERR_PTR(-EINVAL); 235679714f72SAl Viro } 23575955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2358391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 235979714f72SAl Viro if (IS_ERR(d)) { 23605955102cSAl Viro inode_unlock(path->dentry->d_inode); 2361391172c4SAl Viro path_put(path); 236279714f72SAl Viro } 236351689104SPaul Moore putname(filename); 236479714f72SAl Viro return d; 23655590ff0dSUlrich Drepper } 23665590ff0dSUlrich Drepper 2367d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2368d1811465SAl Viro { 2369abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2370abc9f5beSAl Viro flags, path, NULL); 2371d1811465SAl Viro } 23724d359507SAl Viro EXPORT_SYMBOL(kern_path); 2373d1811465SAl Viro 237416f18200SJosef 'Jeff' Sipek /** 237516f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 237616f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 237716f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 237816f18200SJosef 'Jeff' Sipek * @name: pointer to file name 237916f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2380e0a01249SAl Viro * @path: pointer to struct path to fill 238116f18200SJosef 'Jeff' Sipek */ 238216f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 238316f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2384e0a01249SAl Viro struct path *path) 238516f18200SJosef 'Jeff' Sipek { 23869ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 23879ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2388abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2389abc9f5beSAl Viro flags , path, &root); 239016f18200SJosef 'Jeff' Sipek } 23914d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 239216f18200SJosef 'Jeff' Sipek 2393eead1911SChristoph Hellwig /** 23943c9fe8cdSMiklos Szeredi * lookup_hash - lookup single pathname component on already hashed name 23953c9fe8cdSMiklos Szeredi * @name: name and hash to lookup 23963c9fe8cdSMiklos Szeredi * @base: base directory to lookup from 23973c9fe8cdSMiklos Szeredi * 23983c9fe8cdSMiklos Szeredi * The name must have been verified and hashed (see lookup_one_len()). Using 23993c9fe8cdSMiklos Szeredi * this after just full_name_hash() is unsafe. 24003c9fe8cdSMiklos Szeredi * 24013c9fe8cdSMiklos Szeredi * This function also doesn't check for search permission on base directory. 24023c9fe8cdSMiklos Szeredi * 24033c9fe8cdSMiklos Szeredi * Use lookup_one_len_unlocked() instead, unless you really know what you are 24043c9fe8cdSMiklos Szeredi * doing. 24053c9fe8cdSMiklos Szeredi * 24063c9fe8cdSMiklos Szeredi * Do not hold i_mutex; this helper takes i_mutex if necessary. 24073c9fe8cdSMiklos Szeredi */ 24083c9fe8cdSMiklos Szeredi struct dentry *lookup_hash(const struct qstr *name, struct dentry *base) 24093c9fe8cdSMiklos Szeredi { 24103c9fe8cdSMiklos Szeredi struct dentry *ret; 24113c9fe8cdSMiklos Szeredi 24123c9fe8cdSMiklos Szeredi ret = lookup_dcache(name, base, 0); 24133c9fe8cdSMiklos Szeredi if (!ret) 24143c9fe8cdSMiklos Szeredi ret = lookup_slow(name, base, 0); 24153c9fe8cdSMiklos Szeredi 24163c9fe8cdSMiklos Szeredi return ret; 24173c9fe8cdSMiklos Szeredi } 24183c9fe8cdSMiklos Szeredi EXPORT_SYMBOL(lookup_hash); 24193c9fe8cdSMiklos Szeredi 24203c9fe8cdSMiklos Szeredi /** 2421a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2422eead1911SChristoph Hellwig * @name: pathname component to lookup 2423eead1911SChristoph Hellwig * @base: base directory to lookup from 2424eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2425eead1911SChristoph Hellwig * 2426a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24279e7543e9SAl Viro * not be called by generic code. 2428bbddca8eSNeilBrown * 2429bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2430eead1911SChristoph Hellwig */ 2431057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2432057f6c01SJames Morris { 2433057f6c01SJames Morris struct qstr this; 24346a96ba54SAl Viro unsigned int c; 2435cda309deSMiklos Szeredi int err; 2436057f6c01SJames Morris 24375955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24382f9092e1SDavid Woodhouse 24396a96ba54SAl Viro this.name = name; 24406a96ba54SAl Viro this.len = len; 24410145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 24426a96ba54SAl Viro if (!len) 24436a96ba54SAl Viro return ERR_PTR(-EACCES); 24446a96ba54SAl Viro 244521d8a15aSAl Viro if (unlikely(name[0] == '.')) { 244621d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 244721d8a15aSAl Viro return ERR_PTR(-EACCES); 244821d8a15aSAl Viro } 244921d8a15aSAl Viro 24506a96ba54SAl Viro while (len--) { 24516a96ba54SAl Viro c = *(const unsigned char *)name++; 24526a96ba54SAl Viro if (c == '/' || c == '\0') 24536a96ba54SAl Viro return ERR_PTR(-EACCES); 24546a96ba54SAl Viro } 24555a202bcdSAl Viro /* 24565a202bcdSAl Viro * See if the low-level filesystem might want 24575a202bcdSAl Viro * to use its own hash.. 24585a202bcdSAl Viro */ 24595a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2460da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24615a202bcdSAl Viro if (err < 0) 24625a202bcdSAl Viro return ERR_PTR(err); 24635a202bcdSAl Viro } 2464eead1911SChristoph Hellwig 2465cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2466cda309deSMiklos Szeredi if (err) 2467cda309deSMiklos Szeredi return ERR_PTR(err); 2468cda309deSMiklos Szeredi 246972bd866aSAl Viro return __lookup_hash(&this, base, 0); 2470057f6c01SJames Morris } 24714d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2472057f6c01SJames Morris 2473bbddca8eSNeilBrown /** 2474bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2475bbddca8eSNeilBrown * @name: pathname component to lookup 2476bbddca8eSNeilBrown * @base: base directory to lookup from 2477bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2478bbddca8eSNeilBrown * 2479bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2480bbddca8eSNeilBrown * not be called by generic code. 2481bbddca8eSNeilBrown * 2482bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2483bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2484bbddca8eSNeilBrown */ 2485bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2486bbddca8eSNeilBrown struct dentry *base, int len) 2487bbddca8eSNeilBrown { 2488bbddca8eSNeilBrown struct qstr this; 2489bbddca8eSNeilBrown unsigned int c; 2490bbddca8eSNeilBrown int err; 2491bbddca8eSNeilBrown 2492bbddca8eSNeilBrown this.name = name; 2493bbddca8eSNeilBrown this.len = len; 2494bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2495bbddca8eSNeilBrown if (!len) 2496bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2497bbddca8eSNeilBrown 2498bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2499bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2500bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2501bbddca8eSNeilBrown } 2502bbddca8eSNeilBrown 2503bbddca8eSNeilBrown while (len--) { 2504bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2505bbddca8eSNeilBrown if (c == '/' || c == '\0') 2506bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2507bbddca8eSNeilBrown } 2508bbddca8eSNeilBrown /* 2509bbddca8eSNeilBrown * See if the low-level filesystem might want 2510bbddca8eSNeilBrown * to use its own hash.. 2511bbddca8eSNeilBrown */ 2512bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2513bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2514bbddca8eSNeilBrown if (err < 0) 2515bbddca8eSNeilBrown return ERR_PTR(err); 2516bbddca8eSNeilBrown } 2517bbddca8eSNeilBrown 2518bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2519bbddca8eSNeilBrown if (err) 2520bbddca8eSNeilBrown return ERR_PTR(err); 2521bbddca8eSNeilBrown 25223c9fe8cdSMiklos Szeredi return lookup_hash(&this, base); 2523bbddca8eSNeilBrown } 2524bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2525bbddca8eSNeilBrown 2526eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2527eedf265aSEric W. Biederman int path_pts(struct path *path) 2528eedf265aSEric W. Biederman { 2529eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2530eedf265aSEric W. Biederman * the input path. 2531eedf265aSEric W. Biederman */ 2532eedf265aSEric W. Biederman struct dentry *child, *parent; 2533eedf265aSEric W. Biederman struct qstr this; 2534eedf265aSEric W. Biederman int ret; 2535eedf265aSEric W. Biederman 2536eedf265aSEric W. Biederman ret = path_parent_directory(path); 2537eedf265aSEric W. Biederman if (ret) 2538eedf265aSEric W. Biederman return ret; 2539eedf265aSEric W. Biederman 2540eedf265aSEric W. Biederman parent = path->dentry; 2541eedf265aSEric W. Biederman this.name = "pts"; 2542eedf265aSEric W. Biederman this.len = 3; 2543eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2544eedf265aSEric W. Biederman if (!child) 2545eedf265aSEric W. Biederman return -ENOENT; 2546eedf265aSEric W. Biederman 2547eedf265aSEric W. Biederman path->dentry = child; 2548eedf265aSEric W. Biederman dput(parent); 2549eedf265aSEric W. Biederman follow_mount(path); 2550eedf265aSEric W. Biederman return 0; 2551eedf265aSEric W. Biederman } 2552eedf265aSEric W. Biederman #endif 2553eedf265aSEric W. Biederman 25541fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25551fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25561da177e4SLinus Torvalds { 2557abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2558abc9f5beSAl Viro flags, path, NULL); 25591da177e4SLinus Torvalds } 2560b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25611fa1e7f6SAndy Whitcroft 2562873f1eedSJeff Layton /* 2563873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2564873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2565873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2566873f1eedSJeff Layton * path-walking is complete. 2567873f1eedSJeff Layton */ 2568a2ec4a2dSAl Viro static inline struct filename * 2569f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2570f5beed75SAl Viro struct path *parent, 2571f5beed75SAl Viro struct qstr *last, 2572f5beed75SAl Viro int *type, 25739e790bd6SJeff Layton unsigned int flags) 25742ad94ae6SAl Viro { 25759e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 25765c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 25775c31b6ceSAl Viro parent, last, type); 25782ad94ae6SAl Viro } 25792ad94ae6SAl Viro 25808033426eSJeff Layton /** 2581197df04cSAl Viro * mountpoint_last - look up last component for umount 25828033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25838033426eSJeff Layton * @path: pointer to container for result 25848033426eSJeff Layton * 25858033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25868033426eSJeff Layton * need to resolve the path without doing any revalidation. 25878033426eSJeff Layton * 25888033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25898033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25908033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25918033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25928033426eSJeff Layton * bogus and it doesn't exist. 25938033426eSJeff Layton * 25948033426eSJeff Layton * Returns: 25958033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 25968033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 25978033426eSJeff Layton * put in this case. 25988033426eSJeff Layton * 25998033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 26008033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 26018033426eSJeff Layton * The nd->path reference will also be put. 26028033426eSJeff Layton * 26038033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 26048033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 26058033426eSJeff Layton * to the link, and nd->path will *not* be put. 26068033426eSJeff Layton */ 26078033426eSJeff Layton static int 2608197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 26098033426eSJeff Layton { 26108033426eSJeff Layton int error = 0; 26118033426eSJeff Layton struct dentry *dentry; 26128033426eSJeff Layton struct dentry *dir = nd->path.dentry; 26138033426eSJeff Layton 261435759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 261535759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26166e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2617deb106c6SAl Viro return -ECHILD; 26188033426eSJeff Layton } 26198033426eSJeff Layton 26208033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26218033426eSJeff Layton 26228033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26238033426eSJeff Layton error = handle_dots(nd, nd->last_type); 262435759521SAl Viro if (error) 2625deb106c6SAl Viro return error; 26268033426eSJeff Layton dentry = dget(nd->path.dentry); 2627949a852eSAl Viro } else { 26288033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 26298033426eSJeff Layton if (!dentry) { 26308033426eSJeff Layton /* 2631949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2632949a852eSAl Viro * cache, so that means that this dentry is probably 2633949a852eSAl Viro * a symlink or the path doesn't actually point 2634949a852eSAl Viro * to a mounted dentry. 26358033426eSJeff Layton */ 2636949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2637949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2638949a852eSAl Viro if (IS_ERR(dentry)) 2639deb106c6SAl Viro return PTR_ERR(dentry); 26408033426eSJeff Layton } 2641bcceeebaSDave Jones } 2642698934dfSDavid Howells if (d_is_negative(dentry)) { 26438033426eSJeff Layton dput(dentry); 2644deb106c6SAl Viro return -ENOENT; 264535759521SAl Viro } 2646191d7f73SAl Viro if (nd->depth) 2647191d7f73SAl Viro put_link(nd); 26488033426eSJeff Layton path->dentry = dentry; 2649295dc39dSVasily Averin path->mnt = nd->path.mnt; 2650181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2651181548c0SAl Viro d_backing_inode(dentry), 0); 2652deb106c6SAl Viro if (unlikely(error)) 2653d63ff28fSAl Viro return error; 2654295dc39dSVasily Averin mntget(path->mnt); 26558033426eSJeff Layton follow_mount(path); 2656deb106c6SAl Viro return 0; 26578033426eSJeff Layton } 26588033426eSJeff Layton 26598033426eSJeff Layton /** 2660197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26612a78b857SMasanari Iida * @nd: lookup context 26628033426eSJeff Layton * @flags: lookup flags 2663c8a53ee5SAl Viro * @path: pointer to container for result 26648033426eSJeff Layton * 26658033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2666606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26678033426eSJeff Layton */ 26688033426eSJeff Layton static int 2669c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26708033426eSJeff Layton { 2671c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2672368ee9baSAl Viro int err; 2673368ee9baSAl Viro if (IS_ERR(s)) 2674368ee9baSAl Viro return PTR_ERR(s); 26753bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 26763bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 26773bdba28bSAl Viro s = trailing_symlink(nd); 26783bdba28bSAl Viro if (IS_ERR(s)) { 26793bdba28bSAl Viro err = PTR_ERR(s); 26808033426eSJeff Layton break; 26818033426eSJeff Layton } 26823bdba28bSAl Viro } 2683deb106c6SAl Viro terminate_walk(nd); 26848033426eSJeff Layton return err; 26858033426eSJeff Layton } 26868033426eSJeff Layton 26872d864651SAl Viro static int 2688668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26892d864651SAl Viro unsigned int flags) 26902d864651SAl Viro { 26919883d185SAl Viro struct nameidata nd; 2692cbaab2dbSAl Viro int error; 2693668696dcSAl Viro if (IS_ERR(name)) 2694668696dcSAl Viro return PTR_ERR(name); 26959883d185SAl Viro set_nameidata(&nd, dfd, name); 2696c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26972d864651SAl Viro if (unlikely(error == -ECHILD)) 2698c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26992d864651SAl Viro if (unlikely(error == -ESTALE)) 2700c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 27012d864651SAl Viro if (likely(!error)) 2702668696dcSAl Viro audit_inode(name, path->dentry, 0); 27039883d185SAl Viro restore_nameidata(); 2704668696dcSAl Viro putname(name); 27052d864651SAl Viro return error; 27062d864651SAl Viro } 27072d864651SAl Viro 27088033426eSJeff Layton /** 2709197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27108033426eSJeff Layton * @dfd: directory file descriptor 27118033426eSJeff Layton * @name: pathname from userland 27128033426eSJeff Layton * @flags: lookup flags 27138033426eSJeff Layton * @path: pointer to container to hold result 27148033426eSJeff Layton * 27158033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27168033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27178033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27188033426eSJeff Layton * and avoid revalidating the last component. 27198033426eSJeff Layton * 27208033426eSJeff Layton * Returns 0 and populates "path" on success. 27218033426eSJeff Layton */ 27228033426eSJeff Layton int 2723197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27248033426eSJeff Layton struct path *path) 27258033426eSJeff Layton { 2726cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27278033426eSJeff Layton } 27288033426eSJeff Layton 27292d864651SAl Viro int 27302d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27312d864651SAl Viro unsigned int flags) 27322d864651SAl Viro { 2733cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27342d864651SAl Viro } 27352d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27362d864651SAl Viro 2737cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27381da177e4SLinus Torvalds { 27398e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2740da9592edSDavid Howells 27418e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27421da177e4SLinus Torvalds return 0; 27438e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27441da177e4SLinus Torvalds return 0; 274523adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27461da177e4SLinus Torvalds } 2747cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds /* 27501da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27511da177e4SLinus Torvalds * whether the type of victim is right. 27521da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27531da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27541da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27551da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27561da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27571da177e4SLinus Torvalds * a. be owner of dir, or 27581da177e4SLinus Torvalds * b. be owner of victim, or 27591da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27601da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27611da177e4SLinus Torvalds * links pointing to it. 27621da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27631da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27641da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 27651da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 27661da177e4SLinus Torvalds * nfs_async_unlink(). 27671da177e4SLinus Torvalds */ 2768b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27691da177e4SLinus Torvalds { 277063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27711da177e4SLinus Torvalds int error; 27721da177e4SLinus Torvalds 2773b18825a7SDavid Howells if (d_is_negative(victim)) 27741da177e4SLinus Torvalds return -ENOENT; 2775b18825a7SDavid Howells BUG_ON(!inode); 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27784fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27791da177e4SLinus Torvalds 2780f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27811da177e4SLinus Torvalds if (error) 27821da177e4SLinus Torvalds return error; 27831da177e4SLinus Torvalds if (IS_APPEND(dir)) 27841da177e4SLinus Torvalds return -EPERM; 2785b18825a7SDavid Howells 2786b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2787b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 27881da177e4SLinus Torvalds return -EPERM; 27891da177e4SLinus Torvalds if (isdir) { 279044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27911da177e4SLinus Torvalds return -ENOTDIR; 27921da177e4SLinus Torvalds if (IS_ROOT(victim)) 27931da177e4SLinus Torvalds return -EBUSY; 279444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27951da177e4SLinus Torvalds return -EISDIR; 27961da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27971da177e4SLinus Torvalds return -ENOENT; 27981da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27991da177e4SLinus Torvalds return -EBUSY; 28001da177e4SLinus Torvalds return 0; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 28031da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28041da177e4SLinus Torvalds * dir. 28051da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28061da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28071da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 28081da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 28091da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 28101da177e4SLinus Torvalds */ 2811a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28121da177e4SLinus Torvalds { 281314e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28141da177e4SLinus Torvalds if (child->d_inode) 28151da177e4SLinus Torvalds return -EEXIST; 28161da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28171da177e4SLinus Torvalds return -ENOENT; 2818f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28191da177e4SLinus Torvalds } 28201da177e4SLinus Torvalds 28211da177e4SLinus Torvalds /* 28221da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28231da177e4SLinus Torvalds */ 28241da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28251da177e4SLinus Torvalds { 28261da177e4SLinus Torvalds struct dentry *p; 28271da177e4SLinus Torvalds 28281da177e4SLinus Torvalds if (p1 == p2) { 28295955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28301da177e4SLinus Torvalds return NULL; 28311da177e4SLinus Torvalds } 28321da177e4SLinus Torvalds 2833fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28341da177e4SLinus Torvalds 2835e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2836e2761a11SOGAWA Hirofumi if (p) { 28375955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28385955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28391da177e4SLinus Torvalds return p; 28401da177e4SLinus Torvalds } 28411da177e4SLinus Torvalds 2842e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2843e2761a11SOGAWA Hirofumi if (p) { 28445955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28455955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28461da177e4SLinus Torvalds return p; 28471da177e4SLinus Torvalds } 28481da177e4SLinus Torvalds 28495955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28505955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28511da177e4SLinus Torvalds return NULL; 28521da177e4SLinus Torvalds } 28534d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28561da177e4SLinus Torvalds { 28575955102cSAl Viro inode_unlock(p1->d_inode); 28581da177e4SLinus Torvalds if (p1 != p2) { 28595955102cSAl Viro inode_unlock(p2->d_inode); 2860fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28611da177e4SLinus Torvalds } 28621da177e4SLinus Torvalds } 28634d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28641da177e4SLinus Torvalds 28654acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2866312b63fbSAl Viro bool want_excl) 28671da177e4SLinus Torvalds { 2868a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28691da177e4SLinus Torvalds if (error) 28701da177e4SLinus Torvalds return error; 28711da177e4SLinus Torvalds 2872acfa4380SAl Viro if (!dir->i_op->create) 28731da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28741da177e4SLinus Torvalds mode &= S_IALLUGO; 28751da177e4SLinus Torvalds mode |= S_IFREG; 28761da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28771da177e4SLinus Torvalds if (error) 28781da177e4SLinus Torvalds return error; 2879312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2880a74574aaSStephen Smalley if (!error) 2881f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28821da177e4SLinus Torvalds return error; 28831da177e4SLinus Torvalds } 28844d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28851da177e4SLinus Torvalds 2886a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2887a2982cc9SEric W. Biederman { 2888a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2889a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2890a2982cc9SEric W. Biederman } 2891a2982cc9SEric W. Biederman 289273d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 28931da177e4SLinus Torvalds { 28943fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28951da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28961da177e4SLinus Torvalds int error; 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds if (!inode) 28991da177e4SLinus Torvalds return -ENOENT; 29001da177e4SLinus Torvalds 2901c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2902c8fe8f30SChristoph Hellwig case S_IFLNK: 29031da177e4SLinus Torvalds return -ELOOP; 2904c8fe8f30SChristoph Hellwig case S_IFDIR: 2905c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29061da177e4SLinus Torvalds return -EISDIR; 2907c8fe8f30SChristoph Hellwig break; 2908c8fe8f30SChristoph Hellwig case S_IFBLK: 2909c8fe8f30SChristoph Hellwig case S_IFCHR: 2910a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29111da177e4SLinus Torvalds return -EACCES; 2912c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2913c8fe8f30SChristoph Hellwig case S_IFIFO: 2914c8fe8f30SChristoph Hellwig case S_IFSOCK: 29151da177e4SLinus Torvalds flag &= ~O_TRUNC; 2916c8fe8f30SChristoph Hellwig break; 29174a3fd211SDave Hansen } 2918b41572e9SDave Hansen 291962fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2920b41572e9SDave Hansen if (error) 2921b41572e9SDave Hansen return error; 29226146f0d5SMimi Zohar 29231da177e4SLinus Torvalds /* 29241da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29251da177e4SLinus Torvalds */ 29261da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29278737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29287715b521SAl Viro return -EPERM; 29291da177e4SLinus Torvalds if (flag & O_TRUNC) 29307715b521SAl Viro return -EPERM; 29311da177e4SLinus Torvalds } 29321da177e4SLinus Torvalds 29331da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29342e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29357715b521SAl Viro return -EPERM; 29361da177e4SLinus Torvalds 2937f3c7691eSJ. Bruce Fields return 0; 29387715b521SAl Viro } 29397715b521SAl Viro 2940e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29417715b521SAl Viro { 2942e1181ee6SJeff Layton struct path *path = &filp->f_path; 29437715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29447715b521SAl Viro int error = get_write_access(inode); 29451da177e4SLinus Torvalds if (error) 29467715b521SAl Viro return error; 29471da177e4SLinus Torvalds /* 29481da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29491da177e4SLinus Torvalds */ 2950d7a06983SJeff Layton error = locks_verify_locked(filp); 2951be6d3e56SKentaro Takeda if (!error) 2952ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29531da177e4SLinus Torvalds if (!error) { 29547715b521SAl Viro error = do_truncate(path->dentry, 0, 2955d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2956e1181ee6SJeff Layton filp); 29571da177e4SLinus Torvalds } 29581da177e4SLinus Torvalds put_write_access(inode); 2959acd0c935SMimi Zohar return error; 29601da177e4SLinus Torvalds } 29611da177e4SLinus Torvalds 2962d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2963d57999e1SDave Hansen { 29648a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29658a5e929dSAl Viro flag--; 2966d57999e1SDave Hansen return flag; 2967d57999e1SDave Hansen } 2968d57999e1SDave Hansen 2969d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2970d18e9008SMiklos Szeredi { 2971d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2972d18e9008SMiklos Szeredi if (error) 2973d18e9008SMiklos Szeredi return error; 2974d18e9008SMiklos Szeredi 2975d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2976d18e9008SMiklos Szeredi if (error) 2977d18e9008SMiklos Szeredi return error; 2978d18e9008SMiklos Szeredi 2979d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2980d18e9008SMiklos Szeredi } 2981d18e9008SMiklos Szeredi 29821acf0af9SDavid Howells /* 29831acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29841acf0af9SDavid Howells * dentry. 29851acf0af9SDavid Howells * 29861acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29871acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29881acf0af9SDavid Howells * 29891acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29901acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29911acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29921acf0af9SDavid Howells * 29931acf0af9SDavid Howells * Returns an error code otherwise. 29941acf0af9SDavid Howells */ 29952675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 299630d90494SAl Viro struct path *path, struct file *file, 2997015c3bbcSMiklos Szeredi const struct open_flags *op, 29981643b43fSAl Viro int open_flag, umode_t mode, 299947237687SAl Viro int *opened) 3000d18e9008SMiklos Szeredi { 3001d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3002d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3003d18e9008SMiklos Szeredi int error; 3004d18e9008SMiklos Szeredi 3005384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3006d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3007d18e9008SMiklos Szeredi 3008d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3009d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3010d18e9008SMiklos Szeredi 301130d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 301230d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30130fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30140fb1ea09SAl Viro open_to_namei_flags(open_flag), 30150fb1ea09SAl Viro mode, opened); 30166fbd0714SAl Viro d_lookup_done(dentry); 3017384f26e2SAl Viro if (!error) { 3018d18e9008SMiklos Szeredi /* 3019384f26e2SAl Viro * We didn't have the inode before the open, so check open 3020384f26e2SAl Viro * permission here. 3021d18e9008SMiklos Szeredi */ 3022384f26e2SAl Viro int acc_mode = op->acc_mode; 302303da633aSAl Viro if (*opened & FILE_CREATED) { 302403da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 302503da633aSAl Viro fsnotify_create(dir, dentry); 302662fb4a15SAl Viro acc_mode = 0; 302703da633aSAl Viro } 30282675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3029384f26e2SAl Viro if (WARN_ON(error > 0)) 3030384f26e2SAl Viro error = -EINVAL; 3031384f26e2SAl Viro } else if (error > 0) { 3032d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3033d18e9008SMiklos Szeredi error = -EIO; 3034384f26e2SAl Viro } else { 3035d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3036d18e9008SMiklos Szeredi dput(dentry); 3037d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 303810c64ceaSAl Viro } 3039d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3040d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3041d18e9008SMiklos Szeredi path->dentry = dentry; 3042d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30432675a4ebSAl Viro return 1; 3044d18e9008SMiklos Szeredi } 3045d18e9008SMiklos Szeredi } 3046d18e9008SMiklos Szeredi dput(dentry); 3047d18e9008SMiklos Szeredi return error; 3048d18e9008SMiklos Szeredi } 3049d18e9008SMiklos Szeredi 305031e6b01fSNick Piggin /* 30511acf0af9SDavid Howells * Look up and maybe create and open the last component. 3052d58ffd35SMiklos Szeredi * 3053d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3054d58ffd35SMiklos Szeredi * 30551acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30561acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30571acf0af9SDavid Howells * 30581acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30591acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30601acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30611acf0af9SDavid Howells * specified then a negative dentry may be returned. 30621acf0af9SDavid Howells * 30631acf0af9SDavid Howells * An error code is returned otherwise. 30641acf0af9SDavid Howells * 30651acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30661acf0af9SDavid Howells * cleared otherwise prior to returning. 3067d58ffd35SMiklos Szeredi */ 30682675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 306930d90494SAl Viro struct file *file, 3070d58ffd35SMiklos Szeredi const struct open_flags *op, 307164894cf8SAl Viro bool got_write, int *opened) 3072d58ffd35SMiklos Szeredi { 3073d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 307454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30751643b43fSAl Viro int open_flag = op->open_flag; 3076d58ffd35SMiklos Szeredi struct dentry *dentry; 30771643b43fSAl Viro int error, create_error = 0; 30781643b43fSAl Viro umode_t mode = op->mode; 30796fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3080d58ffd35SMiklos Szeredi 3081ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3082ce8644fcSAl Viro return -ENOENT; 3083d58ffd35SMiklos Szeredi 308447237687SAl Viro *opened &= ~FILE_CREATED; 30856fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30866fbd0714SAl Viro for (;;) { 30876fbd0714SAl Viro if (!dentry) { 30886fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3089d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30902675a4ebSAl Viro return PTR_ERR(dentry); 30916fbd0714SAl Viro } 30926fbd0714SAl Viro if (d_in_lookup(dentry)) 30936fbd0714SAl Viro break; 3094d58ffd35SMiklos Szeredi 30956fbd0714SAl Viro if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) 30966fbd0714SAl Viro break; 30976fbd0714SAl Viro 30986fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30996fbd0714SAl Viro if (likely(error > 0)) 31006fbd0714SAl Viro break; 31016fbd0714SAl Viro if (error) 31026fbd0714SAl Viro goto out_dput; 31036fbd0714SAl Viro d_invalidate(dentry); 31046fbd0714SAl Viro dput(dentry); 31056fbd0714SAl Viro dentry = NULL; 31066fbd0714SAl Viro } 31076fbd0714SAl Viro if (dentry->d_inode) { 3108d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3109d18e9008SMiklos Szeredi goto out_no_open; 31106c51e513SAl Viro } 3111d18e9008SMiklos Szeredi 31121643b43fSAl Viro /* 31131643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31141643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31151643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31161643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31171643b43fSAl Viro * 31181643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31191643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31201643b43fSAl Viro */ 31211643b43fSAl Viro if (open_flag & O_CREAT) { 31221643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31231643b43fSAl Viro mode &= ~current_umask(); 31241643b43fSAl Viro if (unlikely(!got_write)) { 31251643b43fSAl Viro create_error = -EROFS; 31261643b43fSAl Viro open_flag &= ~O_CREAT; 31271643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31281643b43fSAl Viro goto no_open; 31291643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31301643b43fSAl Viro } else { 31311643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31321643b43fSAl Viro if (create_error) { 31331643b43fSAl Viro open_flag &= ~O_CREAT; 31341643b43fSAl Viro if (open_flag & O_EXCL) 31351643b43fSAl Viro goto no_open; 31361643b43fSAl Viro } 31371643b43fSAl Viro } 31381643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31391643b43fSAl Viro unlikely(!got_write)) { 31401643b43fSAl Viro /* 31411643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31421643b43fSAl Viro * back to lookup + open 31431643b43fSAl Viro */ 31441643b43fSAl Viro goto no_open; 3145d18e9008SMiklos Szeredi } 3146d18e9008SMiklos Szeredi 31471643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31481643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31491643b43fSAl Viro mode, opened); 31501643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31511643b43fSAl Viro error = create_error; 31521643b43fSAl Viro return error; 31531643b43fSAl Viro } 315454ef4872SMiklos Szeredi 31551643b43fSAl Viro no_open: 31566fbd0714SAl Viro if (d_in_lookup(dentry)) { 315712fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 315812fa5e24SAl Viro nd->flags); 31596fbd0714SAl Viro d_lookup_done(dentry); 316012fa5e24SAl Viro if (unlikely(res)) { 316112fa5e24SAl Viro if (IS_ERR(res)) { 316212fa5e24SAl Viro error = PTR_ERR(res); 316312fa5e24SAl Viro goto out_dput; 316412fa5e24SAl Viro } 316512fa5e24SAl Viro dput(dentry); 316612fa5e24SAl Viro dentry = res; 316712fa5e24SAl Viro } 316854ef4872SMiklos Szeredi } 316954ef4872SMiklos Szeredi 3170d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31711643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 317247237687SAl Viro *opened |= FILE_CREATED; 3173ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3174ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3175ce8644fcSAl Viro error = -EACCES; 3176d58ffd35SMiklos Szeredi goto out_dput; 317777d660a8SMiklos Szeredi } 3178ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31791643b43fSAl Viro open_flag & O_EXCL); 3180d58ffd35SMiklos Szeredi if (error) 3181d58ffd35SMiklos Szeredi goto out_dput; 3182ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3183d58ffd35SMiklos Szeredi } 31841643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31851643b43fSAl Viro error = create_error; 3186d58ffd35SMiklos Szeredi goto out_dput; 3187d58ffd35SMiklos Szeredi } 3188d18e9008SMiklos Szeredi out_no_open: 3189d58ffd35SMiklos Szeredi path->dentry = dentry; 3190d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31912675a4ebSAl Viro return 1; 3192d58ffd35SMiklos Szeredi 3193d58ffd35SMiklos Szeredi out_dput: 3194d58ffd35SMiklos Szeredi dput(dentry); 31952675a4ebSAl Viro return error; 3196d58ffd35SMiklos Szeredi } 3197d58ffd35SMiklos Szeredi 3198d58ffd35SMiklos Szeredi /* 3199fe2d35ffSAl Viro * Handle the last step of open() 320031e6b01fSNick Piggin */ 3201896475d5SAl Viro static int do_last(struct nameidata *nd, 320230d90494SAl Viro struct file *file, const struct open_flags *op, 320376ae2a5aSAl Viro int *opened) 3204fb1cc555SAl Viro { 3205a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3206ca344a89SAl Viro int open_flag = op->open_flag; 320777d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 320864894cf8SAl Viro bool got_write = false; 3209bcda7652SAl Viro int acc_mode = op->acc_mode; 3210254cf582SAl Viro unsigned seq; 3211a1eb3315SMiklos Szeredi struct inode *inode; 321216b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3213896475d5SAl Viro struct path path; 321416b1c1cdSMiklos Szeredi bool retried = false; 321516c2cd71SAl Viro int error; 3216fb1cc555SAl Viro 3217c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3218c3e380b0SAl Viro nd->flags |= op->intent; 3219c3e380b0SAl Viro 3220bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3221fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3222deb106c6SAl Viro if (unlikely(error)) 32232675a4ebSAl Viro return error; 3224e83db167SMiklos Szeredi goto finish_open; 32251f36f774SAl Viro } 3226a2c36b45SAl Viro 3227ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3228fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3229fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3230fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3231254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3232e9742b53SAl Viro if (likely(error > 0)) 323371574865SMiklos Szeredi goto finish_lookup; 323471574865SMiklos Szeredi 3235ce57dfc1SAl Viro if (error < 0) 3236deb106c6SAl Viro return error; 3237a1eb3315SMiklos Szeredi 323837d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32396583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3240b6183df7SMiklos Szeredi } else { 3241fe2d35ffSAl Viro /* create side of things */ 3242a3fbbde7SAl Viro /* 3243b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3244b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3245b6183df7SMiklos Szeredi * about to look up 3246a3fbbde7SAl Viro */ 32479f1fafeeSAl Viro error = complete_walk(nd); 3248e8bb73dfSAl Viro if (error) 32492675a4ebSAl Viro return error; 3250fe2d35ffSAl Viro 325176ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32521f36f774SAl Viro /* trailing slashes? */ 3253deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3254deb106c6SAl Viro return -EISDIR; 3255b6183df7SMiklos Szeredi } 32561f36f774SAl Viro 325716b1c1cdSMiklos Szeredi retry_lookup: 32589cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 325964894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 326064894cf8SAl Viro if (!error) 326164894cf8SAl Viro got_write = true; 326264894cf8SAl Viro /* 326364894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 326464894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 326564894cf8SAl Viro * dropping this one anyway. 326664894cf8SAl Viro */ 326764894cf8SAl Viro } 32689cf843e3SAl Viro if (open_flag & O_CREAT) 32695955102cSAl Viro inode_lock(dir->d_inode); 32709cf843e3SAl Viro else 32719cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3272896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32739cf843e3SAl Viro if (open_flag & O_CREAT) 32745955102cSAl Viro inode_unlock(dir->d_inode); 32759cf843e3SAl Viro else 32769cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3277fb1cc555SAl Viro 32782675a4ebSAl Viro if (error <= 0) { 32792675a4ebSAl Viro if (error) 3280d58ffd35SMiklos Szeredi goto out; 32816c0d46c4SAl Viro 328247237687SAl Viro if ((*opened & FILE_CREATED) || 3283496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 328477d660a8SMiklos Szeredi will_truncate = false; 3285d18e9008SMiklos Szeredi 328676ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3287d18e9008SMiklos Szeredi goto opened; 3288d18e9008SMiklos Szeredi } 3289d18e9008SMiklos Szeredi 329047237687SAl Viro if (*opened & FILE_CREATED) { 32919b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3292ca344a89SAl Viro open_flag &= ~O_TRUNC; 329377d660a8SMiklos Szeredi will_truncate = false; 329462fb4a15SAl Viro acc_mode = 0; 3295896475d5SAl Viro path_to_nameidata(&path, nd); 3296e83db167SMiklos Szeredi goto finish_open_created; 3297fb1cc555SAl Viro } 3298fb1cc555SAl Viro 3299fb1cc555SAl Viro /* 3300d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3301d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3302d18e9008SMiklos Szeredi * necessary...) 3303d18e9008SMiklos Szeredi */ 330464894cf8SAl Viro if (got_write) { 3305d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 330664894cf8SAl Viro got_write = false; 3307d18e9008SMiklos Szeredi } 3308d18e9008SMiklos Szeredi 33096583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33106583fe22SAl Viro path_to_nameidata(&path, nd); 33116583fe22SAl Viro return -ENOENT; 33126583fe22SAl Viro } 33136583fe22SAl Viro 33146583fe22SAl Viro /* 33156583fe22SAl Viro * create/update audit record if it already exists. 33166583fe22SAl Viro */ 33176583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33186583fe22SAl Viro 3319deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3320deb106c6SAl Viro path_to_nameidata(&path, nd); 3321deb106c6SAl Viro return -EEXIST; 3322deb106c6SAl Viro } 3323fb1cc555SAl Viro 3324756daf26SNeilBrown error = follow_managed(&path, nd); 3325deb106c6SAl Viro if (unlikely(error < 0)) 3326deb106c6SAl Viro return error; 3327a3fbbde7SAl Viro 3328254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3329d4565649SAl Viro inode = d_backing_inode(path.dentry); 3330766c4cbfSAl Viro finish_lookup: 3331191d7f73SAl Viro if (nd->depth) 3332191d7f73SAl Viro put_link(nd); 3333181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3334181548c0SAl Viro inode, seq); 3335deb106c6SAl Viro if (unlikely(error)) 3336d63ff28fSAl Viro return error; 3337fb1cc555SAl Viro 3338896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3339896475d5SAl Viro path_to_nameidata(&path, nd); 334016b1c1cdSMiklos Szeredi } else { 334116b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3342896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3343896475d5SAl Viro nd->path.dentry = path.dentry; 334416b1c1cdSMiklos Szeredi 334516b1c1cdSMiklos Szeredi } 3346decf3400SMiklos Szeredi nd->inode = inode; 3347254cf582SAl Viro nd->seq = seq; 3348a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3349bc77daa7SAl Viro finish_open: 3350a3fbbde7SAl Viro error = complete_walk(nd); 335116b1c1cdSMiklos Szeredi if (error) { 335216b1c1cdSMiklos Szeredi path_put(&save_parent); 33532675a4ebSAl Viro return error; 335416b1c1cdSMiklos Szeredi } 335576ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3356fb1cc555SAl Viro error = -EISDIR; 335744b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33582675a4ebSAl Viro goto out; 3359af2f5542SMiklos Szeredi error = -ENOTDIR; 336044b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33612675a4ebSAl Viro goto out; 33624bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 336377d660a8SMiklos Szeredi will_truncate = false; 33646c0d46c4SAl Viro 33650f9d1a10SAl Viro if (will_truncate) { 33660f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33670f9d1a10SAl Viro if (error) 33682675a4ebSAl Viro goto out; 336964894cf8SAl Viro got_write = true; 33700f9d1a10SAl Viro } 3371e83db167SMiklos Szeredi finish_open_created: 3372bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3373ca344a89SAl Viro if (error) 33742675a4ebSAl Viro goto out; 33754aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33764aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 33774aa7c634SMiklos Szeredi if (!error) { 33784aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 33794aa7c634SMiklos Szeredi } else { 338030d90494SAl Viro if (error == -EOPENSTALE) 3381f60dc3dbSMiklos Szeredi goto stale_open; 3382015c3bbcSMiklos Szeredi goto out; 3383f60dc3dbSMiklos Szeredi } 3384a8277b9bSMiklos Szeredi opened: 33852675a4ebSAl Viro error = open_check_o_direct(file); 3386fe9ec829SAl Viro if (!error) 33873034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3388fe9ec829SAl Viro if (!error && will_truncate) 33892675a4ebSAl Viro error = handle_truncate(file); 3390ca344a89SAl Viro out: 3391fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3392fe9ec829SAl Viro fput(file); 3393c80567c8SAl Viro if (unlikely(error > 0)) { 3394c80567c8SAl Viro WARN_ON(1); 3395c80567c8SAl Viro error = -EINVAL; 3396c80567c8SAl Viro } 339764894cf8SAl Viro if (got_write) 33980f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 339916b1c1cdSMiklos Szeredi path_put(&save_parent); 34002675a4ebSAl Viro return error; 3401fb1cc555SAl Viro 3402f60dc3dbSMiklos Szeredi stale_open: 3403f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3404f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3405f60dc3dbSMiklos Szeredi goto out; 3406f60dc3dbSMiklos Szeredi 3407f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3408f60dc3dbSMiklos Szeredi path_put(&nd->path); 3409f60dc3dbSMiklos Szeredi nd->path = save_parent; 3410f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3411f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3412f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 341364894cf8SAl Viro if (got_write) { 3414f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 341564894cf8SAl Viro got_write = false; 3416f60dc3dbSMiklos Szeredi } 3417f60dc3dbSMiklos Szeredi retried = true; 3418f60dc3dbSMiklos Szeredi goto retry_lookup; 3419fb1cc555SAl Viro } 3420fb1cc555SAl Viro 3421c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 342260545d0dSAl Viro const struct open_flags *op, 342360545d0dSAl Viro struct file *file, int *opened) 342460545d0dSAl Viro { 342560545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3426625b6d10SAl Viro struct dentry *child; 342760545d0dSAl Viro struct inode *dir; 3428625b6d10SAl Viro struct path path; 3429c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 343060545d0dSAl Viro if (unlikely(error)) 343160545d0dSAl Viro return error; 3432625b6d10SAl Viro error = mnt_want_write(path.mnt); 343360545d0dSAl Viro if (unlikely(error)) 343460545d0dSAl Viro goto out; 3435625b6d10SAl Viro dir = path.dentry->d_inode; 343660545d0dSAl Viro /* we want directory to be writable */ 3437625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 343860545d0dSAl Viro if (error) 343960545d0dSAl Viro goto out2; 344060545d0dSAl Viro if (!dir->i_op->tmpfile) { 344160545d0dSAl Viro error = -EOPNOTSUPP; 344260545d0dSAl Viro goto out2; 344360545d0dSAl Viro } 3444625b6d10SAl Viro child = d_alloc(path.dentry, &name); 344560545d0dSAl Viro if (unlikely(!child)) { 344660545d0dSAl Viro error = -ENOMEM; 344760545d0dSAl Viro goto out2; 344860545d0dSAl Viro } 3449625b6d10SAl Viro dput(path.dentry); 3450625b6d10SAl Viro path.dentry = child; 3451625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 345260545d0dSAl Viro if (error) 345360545d0dSAl Viro goto out2; 3454c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 345569a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 345662fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 345760545d0dSAl Viro if (error) 345860545d0dSAl Viro goto out2; 3459625b6d10SAl Viro file->f_path.mnt = path.mnt; 3460625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 346160545d0dSAl Viro if (error) 346260545d0dSAl Viro goto out2; 346360545d0dSAl Viro error = open_check_o_direct(file); 3464f4e0c30cSAl Viro if (error) { 346560545d0dSAl Viro fput(file); 3466f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3467f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3468f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3469f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3470f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3471f4e0c30cSAl Viro } 347260545d0dSAl Viro out2: 3473625b6d10SAl Viro mnt_drop_write(path.mnt); 347460545d0dSAl Viro out: 3475625b6d10SAl Viro path_put(&path); 347660545d0dSAl Viro return error; 347760545d0dSAl Viro } 347860545d0dSAl Viro 34796ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34806ac08709SAl Viro { 34816ac08709SAl Viro struct path path; 34826ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34836ac08709SAl Viro if (!error) { 34846ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34856ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34866ac08709SAl Viro path_put(&path); 34876ac08709SAl Viro } 34886ac08709SAl Viro return error; 34896ac08709SAl Viro } 34906ac08709SAl Viro 3491c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3492c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34931da177e4SLinus Torvalds { 3494368ee9baSAl Viro const char *s; 349530d90494SAl Viro struct file *file; 349647237687SAl Viro int opened = 0; 349713aab428SAl Viro int error; 349831e6b01fSNick Piggin 349930d90494SAl Viro file = get_empty_filp(); 35001afc99beSAl Viro if (IS_ERR(file)) 35011afc99beSAl Viro return file; 350231e6b01fSNick Piggin 350330d90494SAl Viro file->f_flags = op->open_flag; 350431e6b01fSNick Piggin 3505bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3506c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3507f15133dfSAl Viro goto out2; 350860545d0dSAl Viro } 350960545d0dSAl Viro 35106ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 35116ac08709SAl Viro error = do_o_path(nd, flags, file); 35126ac08709SAl Viro if (!error) 35136ac08709SAl Viro opened |= FILE_OPENED; 35146ac08709SAl Viro goto out2; 35156ac08709SAl Viro } 35166ac08709SAl Viro 3517c8a53ee5SAl Viro s = path_init(nd, flags); 3518368ee9baSAl Viro if (IS_ERR(s)) { 3519368ee9baSAl Viro put_filp(file); 3520368ee9baSAl Viro return ERR_CAST(s); 3521368ee9baSAl Viro } 35223bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 352376ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 352473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35253bdba28bSAl Viro s = trailing_symlink(nd); 35263bdba28bSAl Viro if (IS_ERR(s)) { 35273bdba28bSAl Viro error = PTR_ERR(s); 35282675a4ebSAl Viro break; 3529806b681cSAl Viro } 35303bdba28bSAl Viro } 3531deb106c6SAl Viro terminate_walk(nd); 3532f15133dfSAl Viro out2: 35332675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35342675a4ebSAl Viro BUG_ON(!error); 353530d90494SAl Viro put_filp(file); 3536015c3bbcSMiklos Szeredi } 35372675a4ebSAl Viro if (unlikely(error)) { 35382675a4ebSAl Viro if (error == -EOPENSTALE) { 35392675a4ebSAl Viro if (flags & LOOKUP_RCU) 35402675a4ebSAl Viro error = -ECHILD; 35412675a4ebSAl Viro else 35422675a4ebSAl Viro error = -ESTALE; 35432675a4ebSAl Viro } 35442675a4ebSAl Viro file = ERR_PTR(error); 35452675a4ebSAl Viro } 35462675a4ebSAl Viro return file; 3547de459215SKirill Korotaev } 35481da177e4SLinus Torvalds 3549669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3550f9652e10SAl Viro const struct open_flags *op) 355113aab428SAl Viro { 35529883d185SAl Viro struct nameidata nd; 3553f9652e10SAl Viro int flags = op->lookup_flags; 355413aab428SAl Viro struct file *filp; 355513aab428SAl Viro 35569883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3557c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 355813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3559c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 356013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3561c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35629883d185SAl Viro restore_nameidata(); 356313aab428SAl Viro return filp; 356413aab428SAl Viro } 356513aab428SAl Viro 356673d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3567f9652e10SAl Viro const char *name, const struct open_flags *op) 356873d049a4SAl Viro { 35699883d185SAl Viro struct nameidata nd; 357073d049a4SAl Viro struct file *file; 357151689104SPaul Moore struct filename *filename; 3572f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 357373d049a4SAl Viro 357473d049a4SAl Viro nd.root.mnt = mnt; 357573d049a4SAl Viro nd.root.dentry = dentry; 357673d049a4SAl Viro 3577b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 357873d049a4SAl Viro return ERR_PTR(-ELOOP); 357973d049a4SAl Viro 358051689104SPaul Moore filename = getname_kernel(name); 3581a1c83681SViresh Kumar if (IS_ERR(filename)) 358251689104SPaul Moore return ERR_CAST(filename); 358351689104SPaul Moore 35849883d185SAl Viro set_nameidata(&nd, -1, filename); 3585c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 358673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3587c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 358873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3589c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35909883d185SAl Viro restore_nameidata(); 359151689104SPaul Moore putname(filename); 359273d049a4SAl Viro return file; 359373d049a4SAl Viro } 359473d049a4SAl Viro 3595fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35961ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35971da177e4SLinus Torvalds { 3598c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3599391172c4SAl Viro struct qstr last; 3600391172c4SAl Viro int type; 3601c30dabfeSJan Kara int err2; 36021ac12b4bSJeff Layton int error; 36031ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 36041ac12b4bSJeff Layton 36051ac12b4bSJeff Layton /* 36061ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 36071ac12b4bSJeff Layton * other flags passed in are ignored! 36081ac12b4bSJeff Layton */ 36091ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 36101ac12b4bSJeff Layton 36115c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36125c31b6ceSAl Viro if (IS_ERR(name)) 36135c31b6ceSAl Viro return ERR_CAST(name); 36141da177e4SLinus Torvalds 3615c663e5d8SChristoph Hellwig /* 3616c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3617c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3618c663e5d8SChristoph Hellwig */ 36195c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3620ed75e95dSAl Viro goto out; 3621c663e5d8SChristoph Hellwig 3622c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3623391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3624c663e5d8SChristoph Hellwig /* 3625c663e5d8SChristoph Hellwig * Do the final lookup. 3626c663e5d8SChristoph Hellwig */ 3627391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36285955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3629391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36301da177e4SLinus Torvalds if (IS_ERR(dentry)) 3631a8104a9fSAl Viro goto unlock; 3632c663e5d8SChristoph Hellwig 3633a8104a9fSAl Viro error = -EEXIST; 3634b18825a7SDavid Howells if (d_is_positive(dentry)) 3635a8104a9fSAl Viro goto fail; 3636b18825a7SDavid Howells 3637c663e5d8SChristoph Hellwig /* 3638c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3639c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3640c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3641c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3642c663e5d8SChristoph Hellwig */ 3643391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3644a8104a9fSAl Viro error = -ENOENT; 3645ed75e95dSAl Viro goto fail; 3646e9baf6e5SAl Viro } 3647c30dabfeSJan Kara if (unlikely(err2)) { 3648c30dabfeSJan Kara error = err2; 3649a8104a9fSAl Viro goto fail; 3650c30dabfeSJan Kara } 3651181c37b6SAl Viro putname(name); 3652e9baf6e5SAl Viro return dentry; 36531da177e4SLinus Torvalds fail: 3654a8104a9fSAl Viro dput(dentry); 3655a8104a9fSAl Viro dentry = ERR_PTR(error); 3656a8104a9fSAl Viro unlock: 36575955102cSAl Viro inode_unlock(path->dentry->d_inode); 3658c30dabfeSJan Kara if (!err2) 3659391172c4SAl Viro mnt_drop_write(path->mnt); 3660ed75e95dSAl Viro out: 3661391172c4SAl Viro path_put(path); 3662181c37b6SAl Viro putname(name); 3663ed75e95dSAl Viro return dentry; 3664dae6ad8fSAl Viro } 3665fa14a0b8SAl Viro 3666fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3667fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3668fa14a0b8SAl Viro { 3669181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3670181c37b6SAl Viro path, lookup_flags); 3671fa14a0b8SAl Viro } 3672dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3673dae6ad8fSAl Viro 3674921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3675921a1650SAl Viro { 3676921a1650SAl Viro dput(dentry); 36775955102cSAl Viro inode_unlock(path->dentry->d_inode); 3678a8104a9fSAl Viro mnt_drop_write(path->mnt); 3679921a1650SAl Viro path_put(path); 3680921a1650SAl Viro } 3681921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3682921a1650SAl Viro 3683520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36841ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3685dae6ad8fSAl Viro { 3686181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3687dae6ad8fSAl Viro } 3688dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3689dae6ad8fSAl Viro 36901a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36911da177e4SLinus Torvalds { 3692a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36931da177e4SLinus Torvalds 36941da177e4SLinus Torvalds if (error) 36951da177e4SLinus Torvalds return error; 36961da177e4SLinus Torvalds 3697975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36981da177e4SLinus Torvalds return -EPERM; 36991da177e4SLinus Torvalds 3700acfa4380SAl Viro if (!dir->i_op->mknod) 37011da177e4SLinus Torvalds return -EPERM; 37021da177e4SLinus Torvalds 370308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 370408ce5f16SSerge E. Hallyn if (error) 370508ce5f16SSerge E. Hallyn return error; 370608ce5f16SSerge E. Hallyn 37071da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 37081da177e4SLinus Torvalds if (error) 37091da177e4SLinus Torvalds return error; 37101da177e4SLinus Torvalds 37111da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3712a74574aaSStephen Smalley if (!error) 3713f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37141da177e4SLinus Torvalds return error; 37151da177e4SLinus Torvalds } 37164d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37171da177e4SLinus Torvalds 3718f69aac00SAl Viro static int may_mknod(umode_t mode) 3719463c3197SDave Hansen { 3720463c3197SDave Hansen switch (mode & S_IFMT) { 3721463c3197SDave Hansen case S_IFREG: 3722463c3197SDave Hansen case S_IFCHR: 3723463c3197SDave Hansen case S_IFBLK: 3724463c3197SDave Hansen case S_IFIFO: 3725463c3197SDave Hansen case S_IFSOCK: 3726463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3727463c3197SDave Hansen return 0; 3728463c3197SDave Hansen case S_IFDIR: 3729463c3197SDave Hansen return -EPERM; 3730463c3197SDave Hansen default: 3731463c3197SDave Hansen return -EINVAL; 3732463c3197SDave Hansen } 3733463c3197SDave Hansen } 3734463c3197SDave Hansen 37358208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37362e4d0924SHeiko Carstens unsigned, dev) 37371da177e4SLinus Torvalds { 37381da177e4SLinus Torvalds struct dentry *dentry; 3739dae6ad8fSAl Viro struct path path; 3740dae6ad8fSAl Viro int error; 3741972567f1SJeff Layton unsigned int lookup_flags = 0; 37421da177e4SLinus Torvalds 37438e4bfca1SAl Viro error = may_mknod(mode); 37448e4bfca1SAl Viro if (error) 37458e4bfca1SAl Viro return error; 3746972567f1SJeff Layton retry: 3747972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3748dae6ad8fSAl Viro if (IS_ERR(dentry)) 3749dae6ad8fSAl Viro return PTR_ERR(dentry); 37502ad94ae6SAl Viro 3751dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3752ce3b0f8dSAl Viro mode &= ~current_umask(); 3753dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3754be6d3e56SKentaro Takeda if (error) 3755a8104a9fSAl Viro goto out; 37561da177e4SLinus Torvalds switch (mode & S_IFMT) { 37571da177e4SLinus Torvalds case 0: case S_IFREG: 3758312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 375905d1a717SMimi Zohar if (!error) 376005d1a717SMimi Zohar ima_post_path_mknod(dentry); 37611da177e4SLinus Torvalds break; 37621da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3763dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37641da177e4SLinus Torvalds new_decode_dev(dev)); 37651da177e4SLinus Torvalds break; 37661da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3767dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37681da177e4SLinus Torvalds break; 37691da177e4SLinus Torvalds } 3770a8104a9fSAl Viro out: 3771921a1650SAl Viro done_path_create(&path, dentry); 3772972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3773972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3774972567f1SJeff Layton goto retry; 3775972567f1SJeff Layton } 37761da177e4SLinus Torvalds return error; 37771da177e4SLinus Torvalds } 37781da177e4SLinus Torvalds 37798208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37805590ff0dSUlrich Drepper { 37815590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37825590ff0dSUlrich Drepper } 37835590ff0dSUlrich Drepper 378418bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37851da177e4SLinus Torvalds { 3786a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37878de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37881da177e4SLinus Torvalds 37891da177e4SLinus Torvalds if (error) 37901da177e4SLinus Torvalds return error; 37911da177e4SLinus Torvalds 3792acfa4380SAl Viro if (!dir->i_op->mkdir) 37931da177e4SLinus Torvalds return -EPERM; 37941da177e4SLinus Torvalds 37951da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37961da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37971da177e4SLinus Torvalds if (error) 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds 38008de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 38018de52778SAl Viro return -EMLINK; 38028de52778SAl Viro 38031da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3804a74574aaSStephen Smalley if (!error) 3805f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 38061da177e4SLinus Torvalds return error; 38071da177e4SLinus Torvalds } 38084d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 38091da177e4SLinus Torvalds 3810a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38111da177e4SLinus Torvalds { 38126902d925SDave Hansen struct dentry *dentry; 3813dae6ad8fSAl Viro struct path path; 3814dae6ad8fSAl Viro int error; 3815b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38161da177e4SLinus Torvalds 3817b76d8b82SJeff Layton retry: 3818b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38196902d925SDave Hansen if (IS_ERR(dentry)) 3820dae6ad8fSAl Viro return PTR_ERR(dentry); 38216902d925SDave Hansen 3822dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3823ce3b0f8dSAl Viro mode &= ~current_umask(); 3824dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3825a8104a9fSAl Viro if (!error) 3826dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3827921a1650SAl Viro done_path_create(&path, dentry); 3828b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3829b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3830b76d8b82SJeff Layton goto retry; 3831b76d8b82SJeff Layton } 38321da177e4SLinus Torvalds return error; 38331da177e4SLinus Torvalds } 38341da177e4SLinus Torvalds 3835a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38365590ff0dSUlrich Drepper { 38375590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38385590ff0dSUlrich Drepper } 38395590ff0dSUlrich Drepper 38401da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38411da177e4SLinus Torvalds { 38421da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38431da177e4SLinus Torvalds 38441da177e4SLinus Torvalds if (error) 38451da177e4SLinus Torvalds return error; 38461da177e4SLinus Torvalds 3847acfa4380SAl Viro if (!dir->i_op->rmdir) 38481da177e4SLinus Torvalds return -EPERM; 38491da177e4SLinus Torvalds 38501d2ef590SAl Viro dget(dentry); 38515955102cSAl Viro inode_lock(dentry->d_inode); 3852912dbc15SSage Weil 38531da177e4SLinus Torvalds error = -EBUSY; 38547af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3855912dbc15SSage Weil goto out; 3856912dbc15SSage Weil 38571da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3858912dbc15SSage Weil if (error) 3859912dbc15SSage Weil goto out; 3860912dbc15SSage Weil 38613cebde24SSage Weil shrink_dcache_parent(dentry); 38621da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3863912dbc15SSage Weil if (error) 3864912dbc15SSage Weil goto out; 3865912dbc15SSage Weil 38661da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3867d83c49f3SAl Viro dont_mount(dentry); 38688ed936b5SEric W. Biederman detach_mounts(dentry); 38691da177e4SLinus Torvalds 3870912dbc15SSage Weil out: 38715955102cSAl Viro inode_unlock(dentry->d_inode); 38721d2ef590SAl Viro dput(dentry); 3873912dbc15SSage Weil if (!error) 3874912dbc15SSage Weil d_delete(dentry); 38751da177e4SLinus Torvalds return error; 38761da177e4SLinus Torvalds } 38774d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38781da177e4SLinus Torvalds 38795590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38801da177e4SLinus Torvalds { 38811da177e4SLinus Torvalds int error = 0; 388291a27b2aSJeff Layton struct filename *name; 38831da177e4SLinus Torvalds struct dentry *dentry; 3884f5beed75SAl Viro struct path path; 3885f5beed75SAl Viro struct qstr last; 3886f5beed75SAl Viro int type; 3887c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3888c6ee9206SJeff Layton retry: 3889f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3890f5beed75SAl Viro &path, &last, &type, lookup_flags); 389191a27b2aSJeff Layton if (IS_ERR(name)) 389291a27b2aSJeff Layton return PTR_ERR(name); 38931da177e4SLinus Torvalds 3894f5beed75SAl Viro switch (type) { 38951da177e4SLinus Torvalds case LAST_DOTDOT: 38961da177e4SLinus Torvalds error = -ENOTEMPTY; 38971da177e4SLinus Torvalds goto exit1; 38981da177e4SLinus Torvalds case LAST_DOT: 38991da177e4SLinus Torvalds error = -EINVAL; 39001da177e4SLinus Torvalds goto exit1; 39011da177e4SLinus Torvalds case LAST_ROOT: 39021da177e4SLinus Torvalds error = -EBUSY; 39031da177e4SLinus Torvalds goto exit1; 39041da177e4SLinus Torvalds } 39050612d9fbSOGAWA Hirofumi 3906f5beed75SAl Viro error = mnt_want_write(path.mnt); 3907c30dabfeSJan Kara if (error) 3908c30dabfeSJan Kara goto exit1; 39090612d9fbSOGAWA Hirofumi 39105955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3911f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39121da177e4SLinus Torvalds error = PTR_ERR(dentry); 39136902d925SDave Hansen if (IS_ERR(dentry)) 39146902d925SDave Hansen goto exit2; 3915e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3916e6bc45d6STheodore Ts'o error = -ENOENT; 3917e6bc45d6STheodore Ts'o goto exit3; 3918e6bc45d6STheodore Ts'o } 3919f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3920be6d3e56SKentaro Takeda if (error) 3921c30dabfeSJan Kara goto exit3; 3922f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39230622753bSDave Hansen exit3: 39241da177e4SLinus Torvalds dput(dentry); 39256902d925SDave Hansen exit2: 39265955102cSAl Viro inode_unlock(path.dentry->d_inode); 3927f5beed75SAl Viro mnt_drop_write(path.mnt); 39281da177e4SLinus Torvalds exit1: 3929f5beed75SAl Viro path_put(&path); 39301da177e4SLinus Torvalds putname(name); 3931c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3932c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3933c6ee9206SJeff Layton goto retry; 3934c6ee9206SJeff Layton } 39351da177e4SLinus Torvalds return error; 39361da177e4SLinus Torvalds } 39371da177e4SLinus Torvalds 39383cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39395590ff0dSUlrich Drepper { 39405590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39415590ff0dSUlrich Drepper } 39425590ff0dSUlrich Drepper 3943b21996e3SJ. Bruce Fields /** 3944b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3945b21996e3SJ. Bruce Fields * @dir: parent directory 3946b21996e3SJ. Bruce Fields * @dentry: victim 3947b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3948b21996e3SJ. Bruce Fields * 3949b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3950b21996e3SJ. Bruce Fields * 3951b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3952b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3953b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3954b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3955b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3956b21996e3SJ. Bruce Fields * 3957b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3958b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3959b21996e3SJ. Bruce Fields * to be NFS exported. 3960b21996e3SJ. Bruce Fields */ 3961b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39621da177e4SLinus Torvalds { 39639accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39641da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39651da177e4SLinus Torvalds 39661da177e4SLinus Torvalds if (error) 39671da177e4SLinus Torvalds return error; 39681da177e4SLinus Torvalds 3969acfa4380SAl Viro if (!dir->i_op->unlink) 39701da177e4SLinus Torvalds return -EPERM; 39711da177e4SLinus Torvalds 39725955102cSAl Viro inode_lock(target); 39738ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39741da177e4SLinus Torvalds error = -EBUSY; 39751da177e4SLinus Torvalds else { 39761da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3977bec1052eSAl Viro if (!error) { 39785a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39795a14696cSJ. Bruce Fields if (error) 3980b21996e3SJ. Bruce Fields goto out; 39811da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39828ed936b5SEric W. Biederman if (!error) { 3983d83c49f3SAl Viro dont_mount(dentry); 39848ed936b5SEric W. Biederman detach_mounts(dentry); 39858ed936b5SEric W. Biederman } 3986bec1052eSAl Viro } 39871da177e4SLinus Torvalds } 3988b21996e3SJ. Bruce Fields out: 39895955102cSAl Viro inode_unlock(target); 39901da177e4SLinus Torvalds 39911da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39921da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39939accbb97SJ. Bruce Fields fsnotify_link_count(target); 39941da177e4SLinus Torvalds d_delete(dentry); 39951da177e4SLinus Torvalds } 39960eeca283SRobert Love 39971da177e4SLinus Torvalds return error; 39981da177e4SLinus Torvalds } 39994d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 40001da177e4SLinus Torvalds 40011da177e4SLinus Torvalds /* 40021da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 40031b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 40041da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 40051da177e4SLinus Torvalds * while waiting on the I/O. 40061da177e4SLinus Torvalds */ 40075590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 40081da177e4SLinus Torvalds { 40092ad94ae6SAl Viro int error; 401091a27b2aSJeff Layton struct filename *name; 40111da177e4SLinus Torvalds struct dentry *dentry; 4012f5beed75SAl Viro struct path path; 4013f5beed75SAl Viro struct qstr last; 4014f5beed75SAl Viro int type; 40151da177e4SLinus Torvalds struct inode *inode = NULL; 4016b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40175d18f813SJeff Layton unsigned int lookup_flags = 0; 40185d18f813SJeff Layton retry: 4019f5beed75SAl Viro name = user_path_parent(dfd, pathname, 4020f5beed75SAl Viro &path, &last, &type, lookup_flags); 402191a27b2aSJeff Layton if (IS_ERR(name)) 402291a27b2aSJeff Layton return PTR_ERR(name); 40232ad94ae6SAl Viro 40241da177e4SLinus Torvalds error = -EISDIR; 4025f5beed75SAl Viro if (type != LAST_NORM) 40261da177e4SLinus Torvalds goto exit1; 40270612d9fbSOGAWA Hirofumi 4028f5beed75SAl Viro error = mnt_want_write(path.mnt); 4029c30dabfeSJan Kara if (error) 4030c30dabfeSJan Kara goto exit1; 4031b21996e3SJ. Bruce Fields retry_deleg: 40325955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4033f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40341da177e4SLinus Torvalds error = PTR_ERR(dentry); 40351da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40361da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4037f5beed75SAl Viro if (last.name[last.len]) 403850338b88STörök Edwin goto slashes; 40391da177e4SLinus Torvalds inode = dentry->d_inode; 4040b18825a7SDavid Howells if (d_is_negative(dentry)) 4041e6bc45d6STheodore Ts'o goto slashes; 40427de9c6eeSAl Viro ihold(inode); 4043f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4044be6d3e56SKentaro Takeda if (error) 4045c30dabfeSJan Kara goto exit2; 4046f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40471da177e4SLinus Torvalds exit2: 40481da177e4SLinus Torvalds dput(dentry); 40491da177e4SLinus Torvalds } 40505955102cSAl Viro inode_unlock(path.dentry->d_inode); 40511da177e4SLinus Torvalds if (inode) 40521da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4053b21996e3SJ. Bruce Fields inode = NULL; 4054b21996e3SJ. Bruce Fields if (delegated_inode) { 40555a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4056b21996e3SJ. Bruce Fields if (!error) 4057b21996e3SJ. Bruce Fields goto retry_deleg; 4058b21996e3SJ. Bruce Fields } 4059f5beed75SAl Viro mnt_drop_write(path.mnt); 40601da177e4SLinus Torvalds exit1: 4061f5beed75SAl Viro path_put(&path); 40621da177e4SLinus Torvalds putname(name); 40635d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40645d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40655d18f813SJeff Layton inode = NULL; 40665d18f813SJeff Layton goto retry; 40675d18f813SJeff Layton } 40681da177e4SLinus Torvalds return error; 40691da177e4SLinus Torvalds 40701da177e4SLinus Torvalds slashes: 4071b18825a7SDavid Howells if (d_is_negative(dentry)) 4072b18825a7SDavid Howells error = -ENOENT; 407344b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4074b18825a7SDavid Howells error = -EISDIR; 4075b18825a7SDavid Howells else 4076b18825a7SDavid Howells error = -ENOTDIR; 40771da177e4SLinus Torvalds goto exit2; 40781da177e4SLinus Torvalds } 40791da177e4SLinus Torvalds 40802e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40815590ff0dSUlrich Drepper { 40825590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40835590ff0dSUlrich Drepper return -EINVAL; 40845590ff0dSUlrich Drepper 40855590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40865590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40875590ff0dSUlrich Drepper 40885590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40895590ff0dSUlrich Drepper } 40905590ff0dSUlrich Drepper 40913480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40925590ff0dSUlrich Drepper { 40935590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40945590ff0dSUlrich Drepper } 40955590ff0dSUlrich Drepper 4096db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40971da177e4SLinus Torvalds { 4098a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40991da177e4SLinus Torvalds 41001da177e4SLinus Torvalds if (error) 41011da177e4SLinus Torvalds return error; 41021da177e4SLinus Torvalds 4103acfa4380SAl Viro if (!dir->i_op->symlink) 41041da177e4SLinus Torvalds return -EPERM; 41051da177e4SLinus Torvalds 41061da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 41071da177e4SLinus Torvalds if (error) 41081da177e4SLinus Torvalds return error; 41091da177e4SLinus Torvalds 41101da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4111a74574aaSStephen Smalley if (!error) 4112f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41131da177e4SLinus Torvalds return error; 41141da177e4SLinus Torvalds } 41154d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41161da177e4SLinus Torvalds 41172e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 41182e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41191da177e4SLinus Torvalds { 41202ad94ae6SAl Viro int error; 412191a27b2aSJeff Layton struct filename *from; 41226902d925SDave Hansen struct dentry *dentry; 4123dae6ad8fSAl Viro struct path path; 4124f46d3567SJeff Layton unsigned int lookup_flags = 0; 41251da177e4SLinus Torvalds 41261da177e4SLinus Torvalds from = getname(oldname); 41271da177e4SLinus Torvalds if (IS_ERR(from)) 41281da177e4SLinus Torvalds return PTR_ERR(from); 4129f46d3567SJeff Layton retry: 4130f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41311da177e4SLinus Torvalds error = PTR_ERR(dentry); 41326902d925SDave Hansen if (IS_ERR(dentry)) 4133dae6ad8fSAl Viro goto out_putname; 41346902d925SDave Hansen 413591a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4136a8104a9fSAl Viro if (!error) 413791a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4138921a1650SAl Viro done_path_create(&path, dentry); 4139f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4140f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4141f46d3567SJeff Layton goto retry; 4142f46d3567SJeff Layton } 41436902d925SDave Hansen out_putname: 41441da177e4SLinus Torvalds putname(from); 41451da177e4SLinus Torvalds return error; 41461da177e4SLinus Torvalds } 41471da177e4SLinus Torvalds 41483480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41495590ff0dSUlrich Drepper { 41505590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41515590ff0dSUlrich Drepper } 41525590ff0dSUlrich Drepper 4153146a8595SJ. Bruce Fields /** 4154146a8595SJ. Bruce Fields * vfs_link - create a new link 4155146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4156146a8595SJ. Bruce Fields * @dir: new parent 4157146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4158146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4159146a8595SJ. Bruce Fields * 4160146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4161146a8595SJ. Bruce Fields * 4162146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4163146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4164146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4165146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4166146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4167146a8595SJ. Bruce Fields * 4168146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4169146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4170146a8595SJ. Bruce Fields * to be NFS exported. 4171146a8595SJ. Bruce Fields */ 4172146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41731da177e4SLinus Torvalds { 41741da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41758de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41761da177e4SLinus Torvalds int error; 41771da177e4SLinus Torvalds 41781da177e4SLinus Torvalds if (!inode) 41791da177e4SLinus Torvalds return -ENOENT; 41801da177e4SLinus Torvalds 4181a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41821da177e4SLinus Torvalds if (error) 41831da177e4SLinus Torvalds return error; 41841da177e4SLinus Torvalds 41851da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41861da177e4SLinus Torvalds return -EXDEV; 41871da177e4SLinus Torvalds 41881da177e4SLinus Torvalds /* 41891da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41901da177e4SLinus Torvalds */ 41911da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41921da177e4SLinus Torvalds return -EPERM; 4193acfa4380SAl Viro if (!dir->i_op->link) 41941da177e4SLinus Torvalds return -EPERM; 41957e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41961da177e4SLinus Torvalds return -EPERM; 41971da177e4SLinus Torvalds 41981da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41991da177e4SLinus Torvalds if (error) 42001da177e4SLinus Torvalds return error; 42011da177e4SLinus Torvalds 42025955102cSAl Viro inode_lock(inode); 4203aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4204f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4205aae8a97dSAneesh Kumar K.V error = -ENOENT; 42068de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 42078de52778SAl Viro error = -EMLINK; 4208146a8595SJ. Bruce Fields else { 4209146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4210146a8595SJ. Bruce Fields if (!error) 42111da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4212146a8595SJ. Bruce Fields } 4213f4e0c30cSAl Viro 4214f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4215f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4216f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4217f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4218f4e0c30cSAl Viro } 42195955102cSAl Viro inode_unlock(inode); 4220e31e14ecSStephen Smalley if (!error) 42217e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42221da177e4SLinus Torvalds return error; 42231da177e4SLinus Torvalds } 42244d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42251da177e4SLinus Torvalds 42261da177e4SLinus Torvalds /* 42271da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42281da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42291da177e4SLinus Torvalds * newname. --KAB 42301da177e4SLinus Torvalds * 42311da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42321da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42331da177e4SLinus Torvalds * and other special files. --ADM 42341da177e4SLinus Torvalds */ 42352e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42362e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42371da177e4SLinus Torvalds { 42381da177e4SLinus Torvalds struct dentry *new_dentry; 4239dae6ad8fSAl Viro struct path old_path, new_path; 4240146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 424111a7b371SAneesh Kumar K.V int how = 0; 42421da177e4SLinus Torvalds int error; 42431da177e4SLinus Torvalds 424411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4245c04030e1SUlrich Drepper return -EINVAL; 424611a7b371SAneesh Kumar K.V /* 4247f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4248f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4249f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 425011a7b371SAneesh Kumar K.V */ 4251f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4252f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4253f0cc6ffbSLinus Torvalds return -ENOENT; 425411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4255f0cc6ffbSLinus Torvalds } 4256c04030e1SUlrich Drepper 425711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 425811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4259442e31caSJeff Layton retry: 426011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42611da177e4SLinus Torvalds if (error) 42622ad94ae6SAl Viro return error; 42632ad94ae6SAl Viro 4264442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4265442e31caSJeff Layton (how & LOOKUP_REVAL)); 42661da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42676902d925SDave Hansen if (IS_ERR(new_dentry)) 4268dae6ad8fSAl Viro goto out; 4269dae6ad8fSAl Viro 4270dae6ad8fSAl Viro error = -EXDEV; 4271dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4272dae6ad8fSAl Viro goto out_dput; 4273800179c9SKees Cook error = may_linkat(&old_path); 4274800179c9SKees Cook if (unlikely(error)) 4275800179c9SKees Cook goto out_dput; 4276dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4277be6d3e56SKentaro Takeda if (error) 4278a8104a9fSAl Viro goto out_dput; 4279146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 428075c3f29dSDave Hansen out_dput: 4281921a1650SAl Viro done_path_create(&new_path, new_dentry); 4282146a8595SJ. Bruce Fields if (delegated_inode) { 4283146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4284d22e6338SOleg Drokin if (!error) { 4285d22e6338SOleg Drokin path_put(&old_path); 4286146a8595SJ. Bruce Fields goto retry; 4287146a8595SJ. Bruce Fields } 4288d22e6338SOleg Drokin } 4289442e31caSJeff Layton if (retry_estale(error, how)) { 4290d22e6338SOleg Drokin path_put(&old_path); 4291442e31caSJeff Layton how |= LOOKUP_REVAL; 4292442e31caSJeff Layton goto retry; 4293442e31caSJeff Layton } 42941da177e4SLinus Torvalds out: 42952d8f3038SAl Viro path_put(&old_path); 42961da177e4SLinus Torvalds 42971da177e4SLinus Torvalds return error; 42981da177e4SLinus Torvalds } 42991da177e4SLinus Torvalds 43003480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 43015590ff0dSUlrich Drepper { 4302c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43035590ff0dSUlrich Drepper } 43045590ff0dSUlrich Drepper 4305bc27027aSMiklos Szeredi /** 4306bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4307bc27027aSMiklos Szeredi * @old_dir: parent of source 4308bc27027aSMiklos Szeredi * @old_dentry: source 4309bc27027aSMiklos Szeredi * @new_dir: parent of destination 4310bc27027aSMiklos Szeredi * @new_dentry: destination 4311bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4312520c8b16SMiklos Szeredi * @flags: rename flags 4313bc27027aSMiklos Szeredi * 4314bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4315bc27027aSMiklos Szeredi * 4316bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4317bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4318bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4319bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4320bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4321bc27027aSMiklos Szeredi * so. 4322bc27027aSMiklos Szeredi * 4323bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4324bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4325bc27027aSMiklos Szeredi * to be NFS exported. 4326bc27027aSMiklos Szeredi * 43271da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43281da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43291da177e4SLinus Torvalds * Problems: 4330d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43311da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43321da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4333a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43341da177e4SLinus Torvalds * story. 43356cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43366cedba89SJ. Bruce Fields * and source (if it is not a directory). 43371b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43381da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43391da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4340a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43411da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43421da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43431da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4344a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43451da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43461da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43471da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4348e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43491b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43501da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4351c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43521da177e4SLinus Torvalds * locking]. 43531da177e4SLinus Torvalds */ 43541da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43558e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4356520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43571da177e4SLinus Torvalds { 43581da177e4SLinus Torvalds int error; 4359bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 436059b0df21SEric Paris const unsigned char *old_name; 4361bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4362bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4363da1ce067SMiklos Szeredi bool new_is_dir = false; 4364da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 43651da177e4SLinus Torvalds 43669409e22aSMiklos Szeredi /* 43679409e22aSMiklos Szeredi * Check source == target. 43689409e22aSMiklos Szeredi * On overlayfs need to look at underlying inodes. 43699409e22aSMiklos Szeredi */ 43709409e22aSMiklos Szeredi if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) 43711da177e4SLinus Torvalds return 0; 43721da177e4SLinus Torvalds 43731da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43741da177e4SLinus Torvalds if (error) 43751da177e4SLinus Torvalds return error; 43761da177e4SLinus Torvalds 4377da1ce067SMiklos Szeredi if (!target) { 4378a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4379da1ce067SMiklos Szeredi } else { 4380da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4381da1ce067SMiklos Szeredi 4382da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43831da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4384da1ce067SMiklos Szeredi else 4385da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4386da1ce067SMiklos Szeredi } 43871da177e4SLinus Torvalds if (error) 43881da177e4SLinus Torvalds return error; 43891da177e4SLinus Torvalds 43907177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 43911da177e4SLinus Torvalds return -EPERM; 43921da177e4SLinus Torvalds 4393520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4394520c8b16SMiklos Szeredi return -EINVAL; 4395520c8b16SMiklos Szeredi 4396bc27027aSMiklos Szeredi /* 4397bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4398bc27027aSMiklos Szeredi * we'll need to flip '..'. 4399bc27027aSMiklos Szeredi */ 4400da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4401da1ce067SMiklos Szeredi if (is_dir) { 4402bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4403bc27027aSMiklos Szeredi if (error) 4404bc27027aSMiklos Szeredi return error; 4405bc27027aSMiklos Szeredi } 4406da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4407da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4408da1ce067SMiklos Szeredi if (error) 4409da1ce067SMiklos Szeredi return error; 4410da1ce067SMiklos Szeredi } 4411da1ce067SMiklos Szeredi } 44120eeca283SRobert Love 44130b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44140b3974ebSMiklos Szeredi flags); 4415bc27027aSMiklos Szeredi if (error) 4416bc27027aSMiklos Szeredi return error; 4417bc27027aSMiklos Szeredi 4418bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4419bc27027aSMiklos Szeredi dget(new_dentry); 4420da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4421bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4422bc27027aSMiklos Szeredi else if (target) 44235955102cSAl Viro inode_lock(target); 4424bc27027aSMiklos Szeredi 4425bc27027aSMiklos Szeredi error = -EBUSY; 44267af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4427bc27027aSMiklos Szeredi goto out; 4428bc27027aSMiklos Szeredi 4429da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4430bc27027aSMiklos Szeredi error = -EMLINK; 4431da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4432bc27027aSMiklos Szeredi goto out; 4433da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4434da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4435da1ce067SMiklos Szeredi goto out; 4436da1ce067SMiklos Szeredi } 4437da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4438bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4439da1ce067SMiklos Szeredi if (!is_dir) { 4440bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4441bc27027aSMiklos Szeredi if (error) 4442bc27027aSMiklos Szeredi goto out; 4443da1ce067SMiklos Szeredi } 4444da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4445bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4446bc27027aSMiklos Szeredi if (error) 4447bc27027aSMiklos Szeredi goto out; 4448bc27027aSMiklos Szeredi } 44497177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4450520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4451520c8b16SMiklos Szeredi new_dir, new_dentry); 4452520c8b16SMiklos Szeredi } else { 44537177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4454520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4455520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4456520c8b16SMiklos Szeredi } 4457bc27027aSMiklos Szeredi if (error) 4458bc27027aSMiklos Szeredi goto out; 4459bc27027aSMiklos Szeredi 4460da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44611da177e4SLinus Torvalds if (is_dir) 4462bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4463bc27027aSMiklos Szeredi dont_mount(new_dentry); 44648ed936b5SEric W. Biederman detach_mounts(new_dentry); 4465bc27027aSMiklos Szeredi } 4466da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4467da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4468bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4469da1ce067SMiklos Szeredi else 4470da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4471da1ce067SMiklos Szeredi } 4472bc27027aSMiklos Szeredi out: 4473da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4474bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4475bc27027aSMiklos Szeredi else if (target) 44765955102cSAl Viro inode_unlock(target); 4477bc27027aSMiklos Szeredi dput(new_dentry); 4478da1ce067SMiklos Szeredi if (!error) { 4479123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4480da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4481da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4482da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4483da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4484da1ce067SMiklos Szeredi } 4485da1ce067SMiklos Szeredi } 44860eeca283SRobert Love fsnotify_oldname_free(old_name); 44870eeca283SRobert Love 44881da177e4SLinus Torvalds return error; 44891da177e4SLinus Torvalds } 44904d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44911da177e4SLinus Torvalds 4492520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4493520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44941da177e4SLinus Torvalds { 44951da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44961da177e4SLinus Torvalds struct dentry *trap; 4497f5beed75SAl Viro struct path old_path, new_path; 4498f5beed75SAl Viro struct qstr old_last, new_last; 4499f5beed75SAl Viro int old_type, new_type; 45008e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 450191a27b2aSJeff Layton struct filename *from; 450291a27b2aSJeff Layton struct filename *to; 4503f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4504c6a94284SJeff Layton bool should_retry = false; 45052ad94ae6SAl Viro int error; 4506520c8b16SMiklos Szeredi 45070d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4508da1ce067SMiklos Szeredi return -EINVAL; 4509da1ce067SMiklos Szeredi 45100d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 45110d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4512520c8b16SMiklos Szeredi return -EINVAL; 4513520c8b16SMiklos Szeredi 45140d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 45150d7a8555SMiklos Szeredi return -EPERM; 45160d7a8555SMiklos Szeredi 4517f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4518f5beed75SAl Viro target_flags = 0; 4519f5beed75SAl Viro 4520c6a94284SJeff Layton retry: 4521f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4522f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 452391a27b2aSJeff Layton if (IS_ERR(from)) { 452491a27b2aSJeff Layton error = PTR_ERR(from); 45251da177e4SLinus Torvalds goto exit; 452691a27b2aSJeff Layton } 45271da177e4SLinus Torvalds 4528f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4529f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 453091a27b2aSJeff Layton if (IS_ERR(to)) { 453191a27b2aSJeff Layton error = PTR_ERR(to); 45321da177e4SLinus Torvalds goto exit1; 453391a27b2aSJeff Layton } 45341da177e4SLinus Torvalds 45351da177e4SLinus Torvalds error = -EXDEV; 4536f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45371da177e4SLinus Torvalds goto exit2; 45381da177e4SLinus Torvalds 45391da177e4SLinus Torvalds error = -EBUSY; 4540f5beed75SAl Viro if (old_type != LAST_NORM) 45411da177e4SLinus Torvalds goto exit2; 45421da177e4SLinus Torvalds 45430a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45440a7c3937SMiklos Szeredi error = -EEXIST; 4545f5beed75SAl Viro if (new_type != LAST_NORM) 45461da177e4SLinus Torvalds goto exit2; 45471da177e4SLinus Torvalds 4548f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4549c30dabfeSJan Kara if (error) 4550c30dabfeSJan Kara goto exit2; 4551c30dabfeSJan Kara 45528e6d782cSJ. Bruce Fields retry_deleg: 4553f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45541da177e4SLinus Torvalds 4555f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45561da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45571da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45581da177e4SLinus Torvalds goto exit3; 45591da177e4SLinus Torvalds /* source must exist */ 45601da177e4SLinus Torvalds error = -ENOENT; 4561b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45621da177e4SLinus Torvalds goto exit4; 4563f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45641da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45651da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45661da177e4SLinus Torvalds goto exit4; 45670a7c3937SMiklos Szeredi error = -EEXIST; 45680a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45690a7c3937SMiklos Szeredi goto exit5; 4570da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4571da1ce067SMiklos Szeredi error = -ENOENT; 4572da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4573da1ce067SMiklos Szeredi goto exit5; 4574da1ce067SMiklos Szeredi 4575da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4576da1ce067SMiklos Szeredi error = -ENOTDIR; 4577f5beed75SAl Viro if (new_last.name[new_last.len]) 4578da1ce067SMiklos Szeredi goto exit5; 4579da1ce067SMiklos Szeredi } 4580da1ce067SMiklos Szeredi } 45810a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45820a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45830a7c3937SMiklos Szeredi error = -ENOTDIR; 4584f5beed75SAl Viro if (old_last.name[old_last.len]) 45850a7c3937SMiklos Szeredi goto exit5; 4586f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45870a7c3937SMiklos Szeredi goto exit5; 45880a7c3937SMiklos Szeredi } 45890a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45900a7c3937SMiklos Szeredi error = -EINVAL; 45910a7c3937SMiklos Szeredi if (old_dentry == trap) 45920a7c3937SMiklos Szeredi goto exit5; 45931da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4594da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45951da177e4SLinus Torvalds error = -ENOTEMPTY; 45961da177e4SLinus Torvalds if (new_dentry == trap) 45971da177e4SLinus Torvalds goto exit5; 45981da177e4SLinus Torvalds 4599f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4600f5beed75SAl Viro &new_path, new_dentry, flags); 4601be6d3e56SKentaro Takeda if (error) 4602c30dabfeSJan Kara goto exit5; 4603f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4604f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4605520c8b16SMiklos Szeredi &delegated_inode, flags); 46061da177e4SLinus Torvalds exit5: 46071da177e4SLinus Torvalds dput(new_dentry); 46081da177e4SLinus Torvalds exit4: 46091da177e4SLinus Torvalds dput(old_dentry); 46101da177e4SLinus Torvalds exit3: 4611f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 46128e6d782cSJ. Bruce Fields if (delegated_inode) { 46138e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 46148e6d782cSJ. Bruce Fields if (!error) 46158e6d782cSJ. Bruce Fields goto retry_deleg; 46168e6d782cSJ. Bruce Fields } 4617f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46181da177e4SLinus Torvalds exit2: 4619c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4620c6a94284SJeff Layton should_retry = true; 4621f5beed75SAl Viro path_put(&new_path); 46222ad94ae6SAl Viro putname(to); 46231da177e4SLinus Torvalds exit1: 4624f5beed75SAl Viro path_put(&old_path); 46251da177e4SLinus Torvalds putname(from); 4626c6a94284SJeff Layton if (should_retry) { 4627c6a94284SJeff Layton should_retry = false; 4628c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4629c6a94284SJeff Layton goto retry; 4630c6a94284SJeff Layton } 46312ad94ae6SAl Viro exit: 46321da177e4SLinus Torvalds return error; 46331da177e4SLinus Torvalds } 46341da177e4SLinus Torvalds 4635520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4636520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4637520c8b16SMiklos Szeredi { 4638520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4639520c8b16SMiklos Szeredi } 4640520c8b16SMiklos Szeredi 4641a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46425590ff0dSUlrich Drepper { 4643520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46445590ff0dSUlrich Drepper } 46455590ff0dSUlrich Drepper 4646787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4647787fb6bcSMiklos Szeredi { 4648787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4649787fb6bcSMiklos Szeredi if (error) 4650787fb6bcSMiklos Szeredi return error; 4651787fb6bcSMiklos Szeredi 4652787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4653787fb6bcSMiklos Szeredi return -EPERM; 4654787fb6bcSMiklos Szeredi 4655787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4656787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4657787fb6bcSMiklos Szeredi } 4658787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4659787fb6bcSMiklos Szeredi 46605d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46611da177e4SLinus Torvalds { 46625d826c84SAl Viro int len = PTR_ERR(link); 46631da177e4SLinus Torvalds if (IS_ERR(link)) 46641da177e4SLinus Torvalds goto out; 46651da177e4SLinus Torvalds 46661da177e4SLinus Torvalds len = strlen(link); 46671da177e4SLinus Torvalds if (len > (unsigned) buflen) 46681da177e4SLinus Torvalds len = buflen; 46691da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46701da177e4SLinus Torvalds len = -EFAULT; 46711da177e4SLinus Torvalds out: 46721da177e4SLinus Torvalds return len; 46731da177e4SLinus Torvalds } 46741da177e4SLinus Torvalds 46751da177e4SLinus Torvalds /* 46761da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46776b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46786b255391SAl Viro * for any given inode is up to filesystem. 46791da177e4SLinus Torvalds */ 46801da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 46811da177e4SLinus Torvalds { 4682fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46835f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46845f2c4179SAl Viro const char *link = inode->i_link; 4685694a1764SMarcin Slusarz int res; 4686cc314eefSLinus Torvalds 4687d4dee48bSAl Viro if (!link) { 4688fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4689680baacbSAl Viro if (IS_ERR(link)) 4690680baacbSAl Viro return PTR_ERR(link); 4691d4dee48bSAl Viro } 4692680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4693fceef393SAl Viro do_delayed_call(&done); 4694694a1764SMarcin Slusarz return res; 46951da177e4SLinus Torvalds } 46964d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 46971da177e4SLinus Torvalds 46981da177e4SLinus Torvalds /* get the link contents into pagecache */ 46996b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4700fceef393SAl Viro struct delayed_call *callback) 47011da177e4SLinus Torvalds { 4702ebd09abbSDuane Griffin char *kaddr; 47031da177e4SLinus Torvalds struct page *page; 47046b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47056b255391SAl Viro 4706d3883d4fSAl Viro if (!dentry) { 4707d3883d4fSAl Viro page = find_get_page(mapping, 0); 4708d3883d4fSAl Viro if (!page) 47096b255391SAl Viro return ERR_PTR(-ECHILD); 4710d3883d4fSAl Viro if (!PageUptodate(page)) { 4711d3883d4fSAl Viro put_page(page); 4712d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4713d3883d4fSAl Viro } 4714d3883d4fSAl Viro } else { 4715090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47161da177e4SLinus Torvalds if (IS_ERR(page)) 47176fe6900eSNick Piggin return (char*)page; 4718d3883d4fSAl Viro } 4719fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 472021fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 472121fc61c7SAl Viro kaddr = page_address(page); 47226b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4723ebd09abbSDuane Griffin return kaddr; 47241da177e4SLinus Torvalds } 47251da177e4SLinus Torvalds 47266b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47271da177e4SLinus Torvalds 4728fceef393SAl Viro void page_put_link(void *arg) 47291da177e4SLinus Torvalds { 4730fceef393SAl Viro put_page(arg); 47311da177e4SLinus Torvalds } 47324d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47331da177e4SLinus Torvalds 4734aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4735aa80deabSAl Viro { 4736fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47376b255391SAl Viro int res = readlink_copy(buffer, buflen, 47386b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4739fceef393SAl Viro &done)); 4740fceef393SAl Viro do_delayed_call(&done); 4741aa80deabSAl Viro return res; 4742aa80deabSAl Viro } 4743aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4744aa80deabSAl Viro 474554566b2cSNick Piggin /* 474654566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 474754566b2cSNick Piggin */ 474854566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47491da177e4SLinus Torvalds { 47501da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47510adb25d2SKirill Korotaev struct page *page; 4752afddba49SNick Piggin void *fsdata; 4753beb497abSDmitriy Monakhov int err; 475454566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 475554566b2cSNick Piggin if (nofs) 475654566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47571da177e4SLinus Torvalds 47587e53cac4SNeilBrown retry: 4759afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 476054566b2cSNick Piggin flags, &page, &fsdata); 47611da177e4SLinus Torvalds if (err) 4762afddba49SNick Piggin goto fail; 4763afddba49SNick Piggin 476421fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4765afddba49SNick Piggin 4766afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4767afddba49SNick Piggin page, fsdata); 47681da177e4SLinus Torvalds if (err < 0) 47691da177e4SLinus Torvalds goto fail; 4770afddba49SNick Piggin if (err < len-1) 4771afddba49SNick Piggin goto retry; 4772afddba49SNick Piggin 47731da177e4SLinus Torvalds mark_inode_dirty(inode); 47741da177e4SLinus Torvalds return 0; 47751da177e4SLinus Torvalds fail: 47761da177e4SLinus Torvalds return err; 47771da177e4SLinus Torvalds } 47784d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47791da177e4SLinus Torvalds 47800adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47810adb25d2SKirill Korotaev { 47820adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4783c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47840adb25d2SKirill Korotaev } 47854d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47860adb25d2SKirill Korotaev 478792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47881da177e4SLinus Torvalds .readlink = generic_readlink, 47896b255391SAl Viro .get_link = page_get_link, 47901da177e4SLinus Torvalds }; 47911da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4792