11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 382a18da7aSGeorge Spelvin #include <linux/bitops.h> 391da177e4SLinus Torvalds #include <asm/uaccess.h> 401da177e4SLinus Torvalds 41e81e3f4dSEric Paris #include "internal.h" 42c7105365SAl Viro #include "mount.h" 43e81e3f4dSEric Paris 441da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 451da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 461da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 471da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 481da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 491da177e4SLinus Torvalds * 501da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 511da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 521da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 531da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 541da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 551da177e4SLinus Torvalds * the special cases of the former code. 561da177e4SLinus Torvalds * 571da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 581da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 591da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 601da177e4SLinus Torvalds * 611da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 621da177e4SLinus Torvalds * resolution to correspond with current state of the code. 631da177e4SLinus Torvalds * 641da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 651da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 661da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 671da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 681da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 691da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 701da177e4SLinus Torvalds */ 711da177e4SLinus Torvalds 721da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 731da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 741da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 751da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 761da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 771da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7825985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 791da177e4SLinus Torvalds * 801da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 811da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 821da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 831da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 841da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 851da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 861da177e4SLinus Torvalds * and in the old Linux semantics. 871da177e4SLinus Torvalds */ 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 901da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 911da177e4SLinus Torvalds * 921da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 931da177e4SLinus Torvalds */ 941da177e4SLinus Torvalds 951da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 961da177e4SLinus Torvalds * inside the path - always follow. 971da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 981da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 991da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1001da177e4SLinus Torvalds * otherwise - don't follow. 1011da177e4SLinus Torvalds * (applied in that order). 1021da177e4SLinus Torvalds * 1031da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1041da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1051da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1061da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1071da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds /* 1101da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 111a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1121da177e4SLinus Torvalds * any extra contention... 1131da177e4SLinus Torvalds */ 1141da177e4SLinus Torvalds 1151da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1161da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1171da177e4SLinus Torvalds * kernel data space before using them.. 1181da177e4SLinus Torvalds * 1191da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1201da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1211da177e4SLinus Torvalds */ 1227950e385SJeff Layton 123fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12491a27b2aSJeff Layton 12551f39a1fSDavid Drysdale struct filename * 12691a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12791a27b2aSJeff Layton { 12894b5d262SAl Viro struct filename *result; 1297950e385SJeff Layton char *kname; 13094b5d262SAl Viro int len; 1311da177e4SLinus Torvalds 1327ac86265SJeff Layton result = audit_reusename(filename); 1337ac86265SJeff Layton if (result) 1347ac86265SJeff Layton return result; 1357ac86265SJeff Layton 1367950e385SJeff Layton result = __getname(); 1373f9f0aa6SLinus Torvalds if (unlikely(!result)) 1384043cde8SEric Paris return ERR_PTR(-ENOMEM); 1391da177e4SLinus Torvalds 1407950e385SJeff Layton /* 1417950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1427950e385SJeff Layton * allocation 1437950e385SJeff Layton */ 144fd2f7cb5SAl Viro kname = (char *)result->iname; 14591a27b2aSJeff Layton result->name = kname; 1467950e385SJeff Layton 14794b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14891a27b2aSJeff Layton if (unlikely(len < 0)) { 14994b5d262SAl Viro __putname(result); 15094b5d262SAl Viro return ERR_PTR(len); 15191a27b2aSJeff Layton } 1523f9f0aa6SLinus Torvalds 1537950e385SJeff Layton /* 1547950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1557950e385SJeff Layton * separate struct filename so we can dedicate the entire 1567950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1577950e385SJeff Layton * userland. 1587950e385SJeff Layton */ 15994b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 160fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1617950e385SJeff Layton kname = (char *)result; 1627950e385SJeff Layton 163fd2f7cb5SAl Viro /* 164fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 165fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 166fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 167fd2f7cb5SAl Viro */ 168fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16994b5d262SAl Viro if (unlikely(!result)) { 17094b5d262SAl Viro __putname(kname); 17194b5d262SAl Viro return ERR_PTR(-ENOMEM); 1727950e385SJeff Layton } 1737950e385SJeff Layton result->name = kname; 17494b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17594b5d262SAl Viro if (unlikely(len < 0)) { 17694b5d262SAl Viro __putname(kname); 17794b5d262SAl Viro kfree(result); 17894b5d262SAl Viro return ERR_PTR(len); 17994b5d262SAl Viro } 18094b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18194b5d262SAl Viro __putname(kname); 18294b5d262SAl Viro kfree(result); 18394b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18494b5d262SAl Viro } 1857950e385SJeff Layton } 1867950e385SJeff Layton 18794b5d262SAl Viro result->refcnt = 1; 1883f9f0aa6SLinus Torvalds /* The empty path is special. */ 1893f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1903f9f0aa6SLinus Torvalds if (empty) 1911fa1e7f6SAndy Whitcroft *empty = 1; 19294b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19394b5d262SAl Viro putname(result); 19494b5d262SAl Viro return ERR_PTR(-ENOENT); 1951da177e4SLinus Torvalds } 19694b5d262SAl Viro } 1977950e385SJeff Layton 1987950e385SJeff Layton result->uptr = filename; 199c4ad8f98SLinus Torvalds result->aname = NULL; 2001da177e4SLinus Torvalds audit_getname(result); 2011da177e4SLinus Torvalds return result; 2023f9f0aa6SLinus Torvalds } 2033f9f0aa6SLinus Torvalds 20491a27b2aSJeff Layton struct filename * 20591a27b2aSJeff Layton getname(const char __user * filename) 206f52e0c11SAl Viro { 207f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 208f52e0c11SAl Viro } 209f52e0c11SAl Viro 210c4ad8f98SLinus Torvalds struct filename * 211c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 212c4ad8f98SLinus Torvalds { 213c4ad8f98SLinus Torvalds struct filename *result; 21408518549SPaul Moore int len = strlen(filename) + 1; 215c4ad8f98SLinus Torvalds 216c4ad8f98SLinus Torvalds result = __getname(); 217c4ad8f98SLinus Torvalds if (unlikely(!result)) 218c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 219c4ad8f98SLinus Torvalds 22008518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 221fd2f7cb5SAl Viro result->name = (char *)result->iname; 22208518549SPaul Moore } else if (len <= PATH_MAX) { 22308518549SPaul Moore struct filename *tmp; 22408518549SPaul Moore 22508518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22608518549SPaul Moore if (unlikely(!tmp)) { 22708518549SPaul Moore __putname(result); 22808518549SPaul Moore return ERR_PTR(-ENOMEM); 22908518549SPaul Moore } 23008518549SPaul Moore tmp->name = (char *)result; 23108518549SPaul Moore result = tmp; 23208518549SPaul Moore } else { 23308518549SPaul Moore __putname(result); 23408518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23508518549SPaul Moore } 23608518549SPaul Moore memcpy((char *)result->name, filename, len); 237c4ad8f98SLinus Torvalds result->uptr = NULL; 238c4ad8f98SLinus Torvalds result->aname = NULL; 23955422d0bSPaul Moore result->refcnt = 1; 240fd3522fdSPaul Moore audit_getname(result); 241c4ad8f98SLinus Torvalds 242c4ad8f98SLinus Torvalds return result; 243c4ad8f98SLinus Torvalds } 244c4ad8f98SLinus Torvalds 24591a27b2aSJeff Layton void putname(struct filename *name) 2461da177e4SLinus Torvalds { 24755422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24855422d0bSPaul Moore 24955422d0bSPaul Moore if (--name->refcnt > 0) 25055422d0bSPaul Moore return; 25155422d0bSPaul Moore 252fd2f7cb5SAl Viro if (name->name != name->iname) { 25355422d0bSPaul Moore __putname(name->name); 25455422d0bSPaul Moore kfree(name); 25555422d0bSPaul Moore } else 25655422d0bSPaul Moore __putname(name); 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 259e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 260e77819e5SLinus Torvalds { 26184635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 262e77819e5SLinus Torvalds struct posix_acl *acl; 263e77819e5SLinus Torvalds 264e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2653567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2663567866bSAl Viro if (!acl) 267e77819e5SLinus Torvalds return -EAGAIN; 2683567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 269b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 270e77819e5SLinus Torvalds return -ECHILD; 271206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 272e77819e5SLinus Torvalds } 273e77819e5SLinus Torvalds 2742982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2754e34e719SChristoph Hellwig if (IS_ERR(acl)) 2764e34e719SChristoph Hellwig return PTR_ERR(acl); 277e77819e5SLinus Torvalds if (acl) { 278e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 279e77819e5SLinus Torvalds posix_acl_release(acl); 280e77819e5SLinus Torvalds return error; 281e77819e5SLinus Torvalds } 28284635d68SLinus Torvalds #endif 283e77819e5SLinus Torvalds 284e77819e5SLinus Torvalds return -EAGAIN; 285e77819e5SLinus Torvalds } 286e77819e5SLinus Torvalds 2875909ccaaSLinus Torvalds /* 288948409c7SAndreas Gruenbacher * This does the basic permission checking 2895909ccaaSLinus Torvalds */ 2907e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2915909ccaaSLinus Torvalds { 29226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2935909ccaaSLinus Torvalds 2948e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2955909ccaaSLinus Torvalds mode >>= 6; 2965909ccaaSLinus Torvalds else { 297e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2987e40145eSAl Viro int error = check_acl(inode, mask); 2995909ccaaSLinus Torvalds if (error != -EAGAIN) 3005909ccaaSLinus Torvalds return error; 3015909ccaaSLinus Torvalds } 3025909ccaaSLinus Torvalds 3035909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3045909ccaaSLinus Torvalds mode >>= 3; 3055909ccaaSLinus Torvalds } 3065909ccaaSLinus Torvalds 3075909ccaaSLinus Torvalds /* 3085909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3095909ccaaSLinus Torvalds */ 3109c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3115909ccaaSLinus Torvalds return 0; 3125909ccaaSLinus Torvalds return -EACCES; 3135909ccaaSLinus Torvalds } 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds /** 3161da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3171da177e4SLinus Torvalds * @inode: inode to check access rights for 3188fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3191da177e4SLinus Torvalds * 3201da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3211da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3221da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 323b74c79e9SNick Piggin * are used for other things. 324b74c79e9SNick Piggin * 325b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 326b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 327b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3281da177e4SLinus Torvalds */ 3292830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3301da177e4SLinus Torvalds { 3315909ccaaSLinus Torvalds int ret; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds /* 334948409c7SAndreas Gruenbacher * Do the basic permission checks. 3351da177e4SLinus Torvalds */ 3367e40145eSAl Viro ret = acl_permission_check(inode, mask); 3375909ccaaSLinus Torvalds if (ret != -EACCES) 3385909ccaaSLinus Torvalds return ret; 3391da177e4SLinus Torvalds 340d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 341d594e7ecSAl Viro /* DACs are overridable for directories */ 34223adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 343d594e7ecSAl Viro return 0; 344d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34623adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 347d594e7ecSAl Viro return 0; 348d594e7ecSAl Viro return -EACCES; 349d594e7ecSAl Viro } 3501da177e4SLinus Torvalds /* 3511da177e4SLinus Torvalds * Read/write DACs are always overridable. 352d594e7ecSAl Viro * Executable DACs are overridable when there is 353d594e7ecSAl Viro * at least one exec bit set. 3541da177e4SLinus Torvalds */ 355d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3571da177e4SLinus Torvalds return 0; 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds /* 3601da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3611da177e4SLinus Torvalds */ 3627ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 363d594e7ecSAl Viro if (mask == MAY_READ) 36423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3651da177e4SLinus Torvalds return 0; 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds return -EACCES; 3681da177e4SLinus Torvalds } 3694d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3701da177e4SLinus Torvalds 3713ddcd056SLinus Torvalds /* 3723ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3733ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3743ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3753ddcd056SLinus Torvalds * permission function, use the fast case". 3763ddcd056SLinus Torvalds */ 3773ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3783ddcd056SLinus Torvalds { 3793ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3803ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3813ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3823ddcd056SLinus Torvalds 3833ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3843ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3853ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3863ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3873ddcd056SLinus Torvalds } 3883ddcd056SLinus Torvalds return generic_permission(inode, mask); 3893ddcd056SLinus Torvalds } 3903ddcd056SLinus Torvalds 391cb23beb5SChristoph Hellwig /** 3920bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3930bdaea90SDavid Howells * @inode: Inode to check permission on 3940bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 395cb23beb5SChristoph Hellwig * 3960bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 397948409c7SAndreas Gruenbacher * 398948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4010bdaea90SDavid Howells * inode_permission(). 402cb23beb5SChristoph Hellwig */ 4030bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4041da177e4SLinus Torvalds { 405e6305c43SAl Viro int retval; 4061da177e4SLinus Torvalds 4073ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4081da177e4SLinus Torvalds /* 4091da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4101da177e4SLinus Torvalds */ 4111da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4121da177e4SLinus Torvalds return -EACCES; 4131da177e4SLinus Torvalds } 4141da177e4SLinus Torvalds 4153ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4161da177e4SLinus Torvalds if (retval) 4171da177e4SLinus Torvalds return retval; 4181da177e4SLinus Torvalds 41908ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 42008ce5f16SSerge E. Hallyn if (retval) 42108ce5f16SSerge E. Hallyn return retval; 42208ce5f16SSerge E. Hallyn 423d09ca739SEric Paris return security_inode_permission(inode, mask); 4241da177e4SLinus Torvalds } 425bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4261da177e4SLinus Torvalds 427f4d6ff89SAl Viro /** 4280bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4290bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 43055852635SRandy Dunlap * @inode: Inode to check permission on 4310bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4320bdaea90SDavid Howells * 4330bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4340bdaea90SDavid Howells */ 4350bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4360bdaea90SDavid Howells { 4370bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4380bdaea90SDavid Howells umode_t mode = inode->i_mode; 4390bdaea90SDavid Howells 4400bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4410bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4420bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4430bdaea90SDavid Howells return -EROFS; 4440bdaea90SDavid Howells } 4450bdaea90SDavid Howells return 0; 4460bdaea90SDavid Howells } 4470bdaea90SDavid Howells 4480bdaea90SDavid Howells /** 4490bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4500bdaea90SDavid Howells * @inode: Inode to check permission on 4510bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4520bdaea90SDavid Howells * 4530bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4540bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4550bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4560bdaea90SDavid Howells * 4570bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4580bdaea90SDavid Howells */ 4590bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4600bdaea90SDavid Howells { 4610bdaea90SDavid Howells int retval; 4620bdaea90SDavid Howells 4630bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4640bdaea90SDavid Howells if (retval) 4650bdaea90SDavid Howells return retval; 4660bdaea90SDavid Howells return __inode_permission(inode, mask); 4670bdaea90SDavid Howells } 4684d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4690bdaea90SDavid Howells 4700bdaea90SDavid Howells /** 4715dd784d0SJan Blunck * path_get - get a reference to a path 4725dd784d0SJan Blunck * @path: path to get the reference to 4735dd784d0SJan Blunck * 4745dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4755dd784d0SJan Blunck */ 476dcf787f3SAl Viro void path_get(const struct path *path) 4775dd784d0SJan Blunck { 4785dd784d0SJan Blunck mntget(path->mnt); 4795dd784d0SJan Blunck dget(path->dentry); 4805dd784d0SJan Blunck } 4815dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4825dd784d0SJan Blunck 4835dd784d0SJan Blunck /** 4841d957f9bSJan Blunck * path_put - put a reference to a path 4851d957f9bSJan Blunck * @path: path to put the reference to 4861d957f9bSJan Blunck * 4871d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4881d957f9bSJan Blunck */ 489dcf787f3SAl Viro void path_put(const struct path *path) 4901da177e4SLinus Torvalds { 4911d957f9bSJan Blunck dput(path->dentry); 4921d957f9bSJan Blunck mntput(path->mnt); 4931da177e4SLinus Torvalds } 4941d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4951da177e4SLinus Torvalds 496894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4971f55a6ecSAl Viro struct nameidata { 4981f55a6ecSAl Viro struct path path; 4991f55a6ecSAl Viro struct qstr last; 5001f55a6ecSAl Viro struct path root; 5011f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5021f55a6ecSAl Viro unsigned int flags; 5039883d185SAl Viro unsigned seq, m_seq; 5041f55a6ecSAl Viro int last_type; 5051f55a6ecSAl Viro unsigned depth; 506756daf26SNeilBrown int total_link_count; 507697fc6caSAl Viro struct saved { 508697fc6caSAl Viro struct path link; 509fceef393SAl Viro struct delayed_call done; 510697fc6caSAl Viro const char *name; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5139883d185SAl Viro struct filename *name; 5149883d185SAl Viro struct nameidata *saved; 515fceef393SAl Viro struct inode *link_inode; 5169883d185SAl Viro unsigned root_seq; 5179883d185SAl Viro int dfd; 5181f55a6ecSAl Viro }; 5191f55a6ecSAl Viro 5209883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 521894bc8c4SAl Viro { 522756daf26SNeilBrown struct nameidata *old = current->nameidata; 523756daf26SNeilBrown p->stack = p->internal; 524c8a53ee5SAl Viro p->dfd = dfd; 525c8a53ee5SAl Viro p->name = name; 526756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5279883d185SAl Viro p->saved = old; 528756daf26SNeilBrown current->nameidata = p; 529894bc8c4SAl Viro } 530894bc8c4SAl Viro 5319883d185SAl Viro static void restore_nameidata(void) 532894bc8c4SAl Viro { 5339883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 534756daf26SNeilBrown 535756daf26SNeilBrown current->nameidata = old; 536756daf26SNeilBrown if (old) 537756daf26SNeilBrown old->total_link_count = now->total_link_count; 538e1a63bbcSAl Viro if (now->stack != now->internal) 539756daf26SNeilBrown kfree(now->stack); 540894bc8c4SAl Viro } 541894bc8c4SAl Viro 542894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 543894bc8c4SAl Viro { 544bc40aee0SAl Viro struct saved *p; 545bc40aee0SAl Viro 546bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 547bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 548bc40aee0SAl Viro GFP_ATOMIC); 549bc40aee0SAl Viro if (unlikely(!p)) 550bc40aee0SAl Viro return -ECHILD; 551bc40aee0SAl Viro } else { 552bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 553894bc8c4SAl Viro GFP_KERNEL); 554894bc8c4SAl Viro if (unlikely(!p)) 555894bc8c4SAl Viro return -ENOMEM; 556bc40aee0SAl Viro } 557894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 558894bc8c4SAl Viro nd->stack = p; 559894bc8c4SAl Viro return 0; 560894bc8c4SAl Viro } 561894bc8c4SAl Viro 562397d425dSEric W. Biederman /** 563397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 564397d425dSEric W. Biederman * @path: nameidate to verify 565397d425dSEric W. Biederman * 566397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 567397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 568397d425dSEric W. Biederman */ 569397d425dSEric W. Biederman static bool path_connected(const struct path *path) 570397d425dSEric W. Biederman { 571397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 572397d425dSEric W. Biederman 573397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 574397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 575397d425dSEric W. Biederman return true; 576397d425dSEric W. Biederman 577397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 578397d425dSEric W. Biederman } 579397d425dSEric W. Biederman 580894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 581894bc8c4SAl Viro { 582da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 583894bc8c4SAl Viro return 0; 584894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 585894bc8c4SAl Viro return 0; 586894bc8c4SAl Viro return __nd_alloc_stack(nd); 587894bc8c4SAl Viro } 588894bc8c4SAl Viro 5897973387aSAl Viro static void drop_links(struct nameidata *nd) 5907973387aSAl Viro { 5917973387aSAl Viro int i = nd->depth; 5927973387aSAl Viro while (i--) { 5937973387aSAl Viro struct saved *last = nd->stack + i; 594fceef393SAl Viro do_delayed_call(&last->done); 595fceef393SAl Viro clear_delayed_call(&last->done); 5967973387aSAl Viro } 5977973387aSAl Viro } 5987973387aSAl Viro 5997973387aSAl Viro static void terminate_walk(struct nameidata *nd) 6007973387aSAl Viro { 6017973387aSAl Viro drop_links(nd); 6027973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 6037973387aSAl Viro int i; 6047973387aSAl Viro path_put(&nd->path); 6057973387aSAl Viro for (i = 0; i < nd->depth; i++) 6067973387aSAl Viro path_put(&nd->stack[i].link); 607102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 608102b8af2SAl Viro path_put(&nd->root); 609102b8af2SAl Viro nd->root.mnt = NULL; 610102b8af2SAl Viro } 6117973387aSAl Viro } else { 6127973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6137973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6147973387aSAl Viro nd->root.mnt = NULL; 6157973387aSAl Viro rcu_read_unlock(); 6167973387aSAl Viro } 6177973387aSAl Viro nd->depth = 0; 6187973387aSAl Viro } 6197973387aSAl Viro 6207973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6217973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6227973387aSAl Viro struct path *path, unsigned seq) 6237973387aSAl Viro { 6247973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6257973387aSAl Viro if (unlikely(res)) { 6267973387aSAl Viro if (res > 0) 6277973387aSAl Viro path->mnt = NULL; 6287973387aSAl Viro path->dentry = NULL; 6297973387aSAl Viro return false; 6307973387aSAl Viro } 6317973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6327973387aSAl Viro path->dentry = NULL; 6337973387aSAl Viro return false; 6347973387aSAl Viro } 6357973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6367973387aSAl Viro } 6377973387aSAl Viro 6387973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6397973387aSAl Viro { 6407973387aSAl Viro int i; 6417973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6427973387aSAl Viro struct saved *last = nd->stack + i; 6437973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6447973387aSAl Viro drop_links(nd); 6457973387aSAl Viro nd->depth = i + 1; 6467973387aSAl Viro return false; 6477973387aSAl Viro } 6487973387aSAl Viro } 6497973387aSAl Viro return true; 6507973387aSAl Viro } 6517973387aSAl Viro 65219660af7SAl Viro /* 65331e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65419660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65519660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65657e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65719660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65819660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65919660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66019660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66131e6b01fSNick Piggin */ 66231e6b01fSNick Piggin 66331e6b01fSNick Piggin /** 66419660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66519660af7SAl Viro * @nd: nameidata pathwalk data 66619660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 6676e9918b7SAl Viro * @seq: seq number to check dentry against 66839191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 66931e6b01fSNick Piggin * 67019660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 67119660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 67219660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 6737973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6747973387aSAl Viro * terminate_walk(). 67531e6b01fSNick Piggin */ 6766e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 67731e6b01fSNick Piggin { 67831e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 67931e6b01fSNick Piggin 68031e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 681e5c832d5SLinus Torvalds 682e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6837973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6847973387aSAl Viro goto out2; 6857973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 6867973387aSAl Viro goto out2; 6877973387aSAl Viro if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) 6887973387aSAl Viro goto out1; 68948a066e7SAl Viro 69015570086SLinus Torvalds /* 69115570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 69215570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 69315570086SLinus Torvalds * 69415570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 69515570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 69615570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 69715570086SLinus Torvalds * since we checked the sequence number of the parent after we got 69815570086SLinus Torvalds * the child sequence number. So we know the parent must still 69915570086SLinus Torvalds * be valid if the child sequence number is still valid. 70015570086SLinus Torvalds */ 70119660af7SAl Viro if (!dentry) { 702e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 703e5c832d5SLinus Torvalds goto out; 70419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 70519660af7SAl Viro } else { 706e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 707e5c832d5SLinus Torvalds goto out; 7086e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 709e5c832d5SLinus Torvalds goto drop_dentry; 71019660af7SAl Viro } 711e5c832d5SLinus Torvalds 712e5c832d5SLinus Torvalds /* 713e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 714e5c832d5SLinus Torvalds * still valid and get it if required. 715e5c832d5SLinus Torvalds */ 716e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7175a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7185a8d87e8SAl Viro rcu_read_unlock(); 7195a8d87e8SAl Viro dput(dentry); 7205a8d87e8SAl Viro return -ECHILD; 7217973387aSAl Viro } 72231e6b01fSNick Piggin } 72331e6b01fSNick Piggin 7248b61e74fSAl Viro rcu_read_unlock(); 72531e6b01fSNick Piggin return 0; 72619660af7SAl Viro 727e5c832d5SLinus Torvalds drop_dentry: 7288b61e74fSAl Viro rcu_read_unlock(); 729e5c832d5SLinus Torvalds dput(dentry); 730d0d27277SLinus Torvalds goto drop_root_mnt; 7317973387aSAl Viro out2: 7327973387aSAl Viro nd->path.mnt = NULL; 7337973387aSAl Viro out1: 7347973387aSAl Viro nd->path.dentry = NULL; 735e5c832d5SLinus Torvalds out: 7368b61e74fSAl Viro rcu_read_unlock(); 737d0d27277SLinus Torvalds drop_root_mnt: 738d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 739d0d27277SLinus Torvalds nd->root.mnt = NULL; 74031e6b01fSNick Piggin return -ECHILD; 74131e6b01fSNick Piggin } 74231e6b01fSNick Piggin 7437973387aSAl Viro static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) 7447973387aSAl Viro { 7457973387aSAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 7467973387aSAl Viro drop_links(nd); 7477973387aSAl Viro nd->depth = 0; 7487973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 7497973387aSAl Viro nd->path.mnt = NULL; 7507973387aSAl Viro nd->path.dentry = NULL; 7517973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7527973387aSAl Viro nd->root.mnt = NULL; 7537973387aSAl Viro rcu_read_unlock(); 7547973387aSAl Viro } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { 7557973387aSAl Viro return 0; 7567973387aSAl Viro } 7577973387aSAl Viro path_put(link); 7587973387aSAl Viro return -ECHILD; 7597973387aSAl Viro } 7607973387aSAl Viro 7614ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76234286d66SNick Piggin { 7634ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 76434286d66SNick Piggin } 76534286d66SNick Piggin 7669f1fafeeSAl Viro /** 7679f1fafeeSAl Viro * complete_walk - successful completion of path walk 7689f1fafeeSAl Viro * @nd: pointer nameidata 76939159de2SJeff Layton * 7709f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7719f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7729f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7739f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7749f1fafeeSAl Viro * need to drop nd->path. 77539159de2SJeff Layton */ 7769f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77739159de2SJeff Layton { 77816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77939159de2SJeff Layton int status; 78039159de2SJeff Layton 7819f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7829f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7839f1fafeeSAl Viro nd->root.mnt = NULL; 7846e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 78548a066e7SAl Viro return -ECHILD; 78648a066e7SAl Viro } 7879f1fafeeSAl Viro 78816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78939159de2SJeff Layton return 0; 79039159de2SJeff Layton 791ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79216c2cd71SAl Viro return 0; 79316c2cd71SAl Viro 794ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79539159de2SJeff Layton if (status > 0) 79639159de2SJeff Layton return 0; 79739159de2SJeff Layton 79816c2cd71SAl Viro if (!status) 79939159de2SJeff Layton status = -ESTALE; 80016c2cd71SAl Viro 80139159de2SJeff Layton return status; 80239159de2SJeff Layton } 80339159de2SJeff Layton 80418d8c860SAl Viro static void set_root(struct nameidata *nd) 8052a737871SAl Viro { 80631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8079e6697e2SAl Viro 8089e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8098f47a016SAl Viro unsigned seq; 810c28cc364SNick Piggin 811c28cc364SNick Piggin do { 812c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81331e6b01fSNick Piggin nd->root = fs->root; 8148f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 815c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8169e6697e2SAl Viro } else { 8179e6697e2SAl Viro get_fs_root(fs, &nd->root); 8189e6697e2SAl Viro } 81931e6b01fSNick Piggin } 82031e6b01fSNick Piggin 8211d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 822051d3812SIan Kent { 823051d3812SIan Kent dput(path->dentry); 8244ac91378SJan Blunck if (path->mnt != nd->path.mnt) 825051d3812SIan Kent mntput(path->mnt); 826051d3812SIan Kent } 827051d3812SIan Kent 8287b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8297b9337aaSNick Piggin struct nameidata *nd) 830051d3812SIan Kent { 83131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8324ac91378SJan Blunck dput(nd->path.dentry); 83331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8344ac91378SJan Blunck mntput(nd->path.mnt); 8359a229683SHuang Shijie } 83631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8374ac91378SJan Blunck nd->path.dentry = path->dentry; 838051d3812SIan Kent } 839051d3812SIan Kent 840248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 841248fb5b9SAl Viro { 842248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 843248fb5b9SAl Viro struct dentry *d; 844248fb5b9SAl Viro nd->path = nd->root; 845248fb5b9SAl Viro d = nd->path.dentry; 846248fb5b9SAl Viro nd->inode = d->d_inode; 847248fb5b9SAl Viro nd->seq = nd->root_seq; 848248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 849248fb5b9SAl Viro return -ECHILD; 850248fb5b9SAl Viro } else { 851248fb5b9SAl Viro path_put(&nd->path); 852248fb5b9SAl Viro nd->path = nd->root; 853248fb5b9SAl Viro path_get(&nd->path); 854248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 855248fb5b9SAl Viro } 856248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 857248fb5b9SAl Viro return 0; 858248fb5b9SAl Viro } 859248fb5b9SAl Viro 860b5fb63c1SChristoph Hellwig /* 8616b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 862b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 863b5fb63c1SChristoph Hellwig */ 8646e77137bSAl Viro void nd_jump_link(struct path *path) 865b5fb63c1SChristoph Hellwig { 8666e77137bSAl Viro struct nameidata *nd = current->nameidata; 867b5fb63c1SChristoph Hellwig path_put(&nd->path); 868b5fb63c1SChristoph Hellwig 869b5fb63c1SChristoph Hellwig nd->path = *path; 870b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 871b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 872b5fb63c1SChristoph Hellwig } 873b5fb63c1SChristoph Hellwig 874b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 875574197e0SAl Viro { 87621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 877fceef393SAl Viro do_delayed_call(&last->done); 8786548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 879b9ff4429SAl Viro path_put(&last->link); 880574197e0SAl Viro } 881574197e0SAl Viro 882561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 883561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 884800179c9SKees Cook 885800179c9SKees Cook /** 886800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88755852635SRandy Dunlap * @nd: nameidata pathwalk data 888800179c9SKees Cook * 889800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 890800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 891800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 892800179c9SKees Cook * processes from failing races against path names that may change out 893800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 894800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 895800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 896800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 897800179c9SKees Cook * 898800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 899800179c9SKees Cook */ 900fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 901800179c9SKees Cook { 902800179c9SKees Cook const struct inode *inode; 903800179c9SKees Cook const struct inode *parent; 904800179c9SKees Cook 905800179c9SKees Cook if (!sysctl_protected_symlinks) 906800179c9SKees Cook return 0; 907800179c9SKees Cook 908800179c9SKees Cook /* Allowed if owner and follower match. */ 909fceef393SAl Viro inode = nd->link_inode; 91081abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 911800179c9SKees Cook return 0; 912800179c9SKees Cook 913800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 914aa65fa35SAl Viro parent = nd->inode; 915800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 916800179c9SKees Cook return 0; 917800179c9SKees Cook 918800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 91981abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 920800179c9SKees Cook return 0; 921800179c9SKees Cook 92231956502SAl Viro if (nd->flags & LOOKUP_RCU) 92331956502SAl Viro return -ECHILD; 92431956502SAl Viro 9251cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 926800179c9SKees Cook return -EACCES; 927800179c9SKees Cook } 928800179c9SKees Cook 929800179c9SKees Cook /** 930800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 931800179c9SKees Cook * @inode: the source inode to hardlink from 932800179c9SKees Cook * 933800179c9SKees Cook * Return false if at least one of the following conditions: 934800179c9SKees Cook * - inode is not a regular file 935800179c9SKees Cook * - inode is setuid 936800179c9SKees Cook * - inode is setgid and group-exec 937800179c9SKees Cook * - access failure for read and write 938800179c9SKees Cook * 939800179c9SKees Cook * Otherwise returns true. 940800179c9SKees Cook */ 941800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 942800179c9SKees Cook { 943800179c9SKees Cook umode_t mode = inode->i_mode; 944800179c9SKees Cook 945800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 946800179c9SKees Cook if (!S_ISREG(mode)) 947800179c9SKees Cook return false; 948800179c9SKees Cook 949800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 950800179c9SKees Cook if (mode & S_ISUID) 951800179c9SKees Cook return false; 952800179c9SKees Cook 953800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 954800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 955800179c9SKees Cook return false; 956800179c9SKees Cook 957800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 958800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 959800179c9SKees Cook return false; 960800179c9SKees Cook 961800179c9SKees Cook return true; 962800179c9SKees Cook } 963800179c9SKees Cook 964800179c9SKees Cook /** 965800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 966800179c9SKees Cook * @link: the source to hardlink from 967800179c9SKees Cook * 968800179c9SKees Cook * Block hardlink when all of: 969800179c9SKees Cook * - sysctl_protected_hardlinks enabled 970800179c9SKees Cook * - fsuid does not match inode 971800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 972f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 973800179c9SKees Cook * 974800179c9SKees Cook * Returns 0 if successful, -ve on error. 975800179c9SKees Cook */ 976800179c9SKees Cook static int may_linkat(struct path *link) 977800179c9SKees Cook { 978800179c9SKees Cook struct inode *inode; 979800179c9SKees Cook 980800179c9SKees Cook if (!sysctl_protected_hardlinks) 981800179c9SKees Cook return 0; 982800179c9SKees Cook 983800179c9SKees Cook inode = link->dentry->d_inode; 984800179c9SKees Cook 985800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 986800179c9SKees Cook * otherwise, it must be a safe source. 987800179c9SKees Cook */ 988f2ca3796SDirk Steinmetz if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) 989800179c9SKees Cook return 0; 990800179c9SKees Cook 991a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 992800179c9SKees Cook return -EPERM; 993800179c9SKees Cook } 994800179c9SKees Cook 9953b2e7f75SAl Viro static __always_inline 9963b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 9971da177e4SLinus Torvalds { 998ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 9991cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1000fceef393SAl Viro struct inode *inode = nd->link_inode; 10016d7b5aaeSAl Viro int error; 10020a959df5SAl Viro const char *res; 10031da177e4SLinus Torvalds 10048fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10058fa9dd24SNeilBrown touch_atime(&last->link); 10068fa9dd24SNeilBrown cond_resched(); 10078fa9dd24SNeilBrown } else if (atime_needs_update(&last->link, inode)) { 10088fa9dd24SNeilBrown if (unlikely(unlazy_walk(nd, NULL, 0))) 10098fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10108fa9dd24SNeilBrown touch_atime(&last->link); 10118fa9dd24SNeilBrown } 10128fa9dd24SNeilBrown 1013bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1014bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1015bda0be7aSNeilBrown if (unlikely(error)) 10166920a440SAl Viro return ERR_PTR(error); 101736f3b4f6SAl Viro 101886acdca1SAl Viro nd->last_type = LAST_BIND; 1019d4dee48bSAl Viro res = inode->i_link; 1020d4dee48bSAl Viro if (!res) { 1021fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1022fceef393SAl Viro struct delayed_call *); 1023fceef393SAl Viro get = inode->i_op->get_link; 10248c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1025fceef393SAl Viro res = get(NULL, inode, &last->done); 10266b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10278c1b4566SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 10288c1b4566SAl Viro return ERR_PTR(-ECHILD); 1029fceef393SAl Viro res = get(dentry, inode, &last->done); 10308c1b4566SAl Viro } 10316b255391SAl Viro } else { 1032fceef393SAl Viro res = get(dentry, inode, &last->done); 10336b255391SAl Viro } 1034fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1035fab51e8aSAl Viro return res; 10360a959df5SAl Viro } 1037fab51e8aSAl Viro if (*res == '/') { 1038fab51e8aSAl Viro if (!nd->root.mnt) 1039fab51e8aSAl Viro set_root(nd); 1040248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1041fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1042fab51e8aSAl Viro while (unlikely(*++res == '/')) 1043fab51e8aSAl Viro ; 1044fab51e8aSAl Viro } 1045fab51e8aSAl Viro if (!*res) 1046fab51e8aSAl Viro res = NULL; 10470a959df5SAl Viro return res; 10480a959df5SAl Viro } 10496d7b5aaeSAl Viro 1050f015f126SDavid Howells /* 1051f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1052f015f126SDavid Howells * 1053f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1054f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1055f015f126SDavid Howells * Up is towards /. 1056f015f126SDavid Howells * 1057f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1058f015f126SDavid Howells * root. 1059f015f126SDavid Howells */ 1060bab77ebfSAl Viro int follow_up(struct path *path) 10611da177e4SLinus Torvalds { 10620714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10630714a533SAl Viro struct mount *parent; 10641da177e4SLinus Torvalds struct dentry *mountpoint; 106599b7db7bSNick Piggin 106648a066e7SAl Viro read_seqlock_excl(&mount_lock); 10670714a533SAl Viro parent = mnt->mnt_parent; 10683c0a6163SAl Viro if (parent == mnt) { 106948a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10701da177e4SLinus Torvalds return 0; 10711da177e4SLinus Torvalds } 10720714a533SAl Viro mntget(&parent->mnt); 1073a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107448a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1075bab77ebfSAl Viro dput(path->dentry); 1076bab77ebfSAl Viro path->dentry = mountpoint; 1077bab77ebfSAl Viro mntput(path->mnt); 10780714a533SAl Viro path->mnt = &parent->mnt; 10791da177e4SLinus Torvalds return 1; 10801da177e4SLinus Torvalds } 10814d359507SAl Viro EXPORT_SYMBOL(follow_up); 10821da177e4SLinus Torvalds 1083b5c84bf6SNick Piggin /* 10849875cf80SDavid Howells * Perform an automount 10859875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10869875cf80SDavid Howells * were called with. 10871da177e4SLinus Torvalds */ 1088756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10899875cf80SDavid Howells bool *need_mntput) 109031e6b01fSNick Piggin { 10919875cf80SDavid Howells struct vfsmount *mnt; 1092ea5b778aSDavid Howells int err; 10939875cf80SDavid Howells 10949875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10959875cf80SDavid Howells return -EREMOTE; 10969875cf80SDavid Howells 10970ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 10980ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 10990ec26fd0SMiklos Szeredi * the name. 11000ec26fd0SMiklos Szeredi * 11010ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11025a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11030ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11040ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11050ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11060ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11075a30d8a2SDavid Howells */ 1108756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1109d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11105a30d8a2SDavid Howells path->dentry->d_inode) 11119875cf80SDavid Howells return -EISDIR; 11120ec26fd0SMiklos Szeredi 1113756daf26SNeilBrown nd->total_link_count++; 1114756daf26SNeilBrown if (nd->total_link_count >= 40) 11159875cf80SDavid Howells return -ELOOP; 11169875cf80SDavid Howells 11179875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11189875cf80SDavid Howells if (IS_ERR(mnt)) { 11199875cf80SDavid Howells /* 11209875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11219875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11229875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11239875cf80SDavid Howells * 11249875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11259875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11269875cf80SDavid Howells * the path is inaccessible and we should say so. 11279875cf80SDavid Howells */ 1128756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11299875cf80SDavid Howells return -EREMOTE; 11309875cf80SDavid Howells return PTR_ERR(mnt); 113131e6b01fSNick Piggin } 1132ea5b778aSDavid Howells 11339875cf80SDavid Howells if (!mnt) /* mount collision */ 11349875cf80SDavid Howells return 0; 11359875cf80SDavid Howells 11368aef1884SAl Viro if (!*need_mntput) { 11378aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11388aef1884SAl Viro mntget(path->mnt); 11398aef1884SAl Viro *need_mntput = true; 11408aef1884SAl Viro } 114119a167afSAl Viro err = finish_automount(mnt, path); 1142ea5b778aSDavid Howells 1143ea5b778aSDavid Howells switch (err) { 1144ea5b778aSDavid Howells case -EBUSY: 1145ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 114619a167afSAl Viro return 0; 1147ea5b778aSDavid Howells case 0: 11488aef1884SAl Viro path_put(path); 11499875cf80SDavid Howells path->mnt = mnt; 11509875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11519875cf80SDavid Howells return 0; 115219a167afSAl Viro default: 115319a167afSAl Viro return err; 11549875cf80SDavid Howells } 115519a167afSAl Viro 1156ea5b778aSDavid Howells } 11579875cf80SDavid Howells 11589875cf80SDavid Howells /* 11599875cf80SDavid Howells * Handle a dentry that is managed in some way. 1160cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11619875cf80SDavid Howells * - Flagged as mountpoint 11629875cf80SDavid Howells * - Flagged as automount point 11639875cf80SDavid Howells * 11649875cf80SDavid Howells * This may only be called in refwalk mode. 11659875cf80SDavid Howells * 11669875cf80SDavid Howells * Serialization is taken care of in namespace.c 11679875cf80SDavid Howells */ 1168756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11699875cf80SDavid Howells { 11708aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11719875cf80SDavid Howells unsigned managed; 11729875cf80SDavid Howells bool need_mntput = false; 11738aef1884SAl Viro int ret = 0; 11749875cf80SDavid Howells 11759875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11769875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11779875cf80SDavid Howells * the components of that value change under us */ 11789875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 11799875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11809875cf80SDavid Howells unlikely(managed != 0)) { 1181cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1182cc53ce53SDavid Howells * being held. */ 1183cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1184cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1185cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 11861aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1187cc53ce53SDavid Howells if (ret < 0) 11888aef1884SAl Viro break; 1189cc53ce53SDavid Howells } 1190cc53ce53SDavid Howells 11919875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11929875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11939875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11949875cf80SDavid Howells if (mounted) { 11959875cf80SDavid Howells dput(path->dentry); 11969875cf80SDavid Howells if (need_mntput) 1197463ffb2eSAl Viro mntput(path->mnt); 1198463ffb2eSAl Viro path->mnt = mounted; 1199463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12009875cf80SDavid Howells need_mntput = true; 12019875cf80SDavid Howells continue; 1202463ffb2eSAl Viro } 1203463ffb2eSAl Viro 12049875cf80SDavid Howells /* Something is mounted on this dentry in another 12059875cf80SDavid Howells * namespace and/or whatever was mounted there in this 120648a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 120748a066e7SAl Viro * get it */ 12081da177e4SLinus Torvalds } 12099875cf80SDavid Howells 12109875cf80SDavid Howells /* Handle an automount point */ 12119875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1212756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12139875cf80SDavid Howells if (ret < 0) 12148aef1884SAl Viro break; 12159875cf80SDavid Howells continue; 12169875cf80SDavid Howells } 12179875cf80SDavid Howells 12189875cf80SDavid Howells /* We didn't change the current path point */ 12199875cf80SDavid Howells break; 12209875cf80SDavid Howells } 12218aef1884SAl Viro 12228aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12238aef1884SAl Viro mntput(path->mnt); 1224e9742b53SAl Viro if (ret == -EISDIR || !ret) 1225e9742b53SAl Viro ret = 1; 12268402752eSAl Viro if (need_mntput) 12278402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12288402752eSAl Viro if (unlikely(ret < 0)) 12298402752eSAl Viro path_put_conditional(path, nd); 12308402752eSAl Viro return ret; 12311da177e4SLinus Torvalds } 12321da177e4SLinus Torvalds 1233cc53ce53SDavid Howells int follow_down_one(struct path *path) 12341da177e4SLinus Torvalds { 12351da177e4SLinus Torvalds struct vfsmount *mounted; 12361da177e4SLinus Torvalds 12371c755af4SAl Viro mounted = lookup_mnt(path); 12381da177e4SLinus Torvalds if (mounted) { 12399393bd07SAl Viro dput(path->dentry); 12409393bd07SAl Viro mntput(path->mnt); 12419393bd07SAl Viro path->mnt = mounted; 12429393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12431da177e4SLinus Torvalds return 1; 12441da177e4SLinus Torvalds } 12451da177e4SLinus Torvalds return 0; 12461da177e4SLinus Torvalds } 12474d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12481da177e4SLinus Torvalds 1249b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 125062a7375eSIan Kent { 1251b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1252b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 125362a7375eSIan Kent } 125462a7375eSIan Kent 12559875cf80SDavid Howells /* 1256287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1257287548e4SAl Viro * we meet a managed dentry that would need blocking. 12589875cf80SDavid Howells */ 12599875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1260254cf582SAl Viro struct inode **inode, unsigned *seqp) 12619875cf80SDavid Howells { 126262a7375eSIan Kent for (;;) { 1263c7105365SAl Viro struct mount *mounted; 126462a7375eSIan Kent /* 126562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 126662a7375eSIan Kent * that wants to block transit. 126762a7375eSIan Kent */ 1268b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1269b8faf035SNeilBrown case -ECHILD: 1270b8faf035SNeilBrown default: 1271ab90911fSDavid Howells return false; 1272b8faf035SNeilBrown case -EISDIR: 1273b8faf035SNeilBrown return true; 1274b8faf035SNeilBrown case 0: 1275b8faf035SNeilBrown break; 1276b8faf035SNeilBrown } 127762a7375eSIan Kent 127862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1279b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 128062a7375eSIan Kent 1281474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12829875cf80SDavid Howells if (!mounted) 12839875cf80SDavid Howells break; 1284c7105365SAl Viro path->mnt = &mounted->mnt; 1285c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1286a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1287254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 128859430262SLinus Torvalds /* 128959430262SLinus Torvalds * Update the inode too. We don't need to re-check the 129059430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129159430262SLinus Torvalds * because a mount-point is always pinned. 129259430262SLinus Torvalds */ 129359430262SLinus Torvalds *inode = path->dentry->d_inode; 12949875cf80SDavid Howells } 1295f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1296b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1297287548e4SAl Viro } 1298287548e4SAl Viro 129931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 130031e6b01fSNick Piggin { 13014023bfc9SAl Viro struct inode *inode = nd->inode; 130231e6b01fSNick Piggin 130331e6b01fSNick Piggin while (1) { 1304aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130531e6b01fSNick Piggin break; 130631e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 130731e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 130831e6b01fSNick Piggin struct dentry *parent = old->d_parent; 130931e6b01fSNick Piggin unsigned seq; 131031e6b01fSNick Piggin 13114023bfc9SAl Viro inode = parent->d_inode; 131231e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1313aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1314aed434adSAl Viro return -ECHILD; 131531e6b01fSNick Piggin nd->path.dentry = parent; 131631e6b01fSNick Piggin nd->seq = seq; 1317397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1318397d425dSEric W. Biederman return -ENOENT; 131931e6b01fSNick Piggin break; 1320aed434adSAl Viro } else { 1321aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1322aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1323aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1324aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1325aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1326aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1327aed434adSAl Viro return -ECHILD; 1328aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 132931e6b01fSNick Piggin break; 1330aed434adSAl Viro /* we know that mountpoint was pinned */ 1331aed434adSAl Viro nd->path.dentry = mountpoint; 1332aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1333aed434adSAl Viro inode = inode2; 1334aed434adSAl Viro nd->seq = seq; 133531e6b01fSNick Piggin } 1336aed434adSAl Viro } 1337aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1338b37199e6SAl Viro struct mount *mounted; 1339b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1340aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1341aed434adSAl Viro return -ECHILD; 1342b37199e6SAl Viro if (!mounted) 1343b37199e6SAl Viro break; 1344b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1345b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13464023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1347b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1348b37199e6SAl Viro } 13494023bfc9SAl Viro nd->inode = inode; 135031e6b01fSNick Piggin return 0; 135131e6b01fSNick Piggin } 135231e6b01fSNick Piggin 13539875cf80SDavid Howells /* 1354cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1355cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1356cc53ce53SDavid Howells * caller is permitted to proceed or not. 1357cc53ce53SDavid Howells */ 13587cc90cc3SAl Viro int follow_down(struct path *path) 1359cc53ce53SDavid Howells { 1360cc53ce53SDavid Howells unsigned managed; 1361cc53ce53SDavid Howells int ret; 1362cc53ce53SDavid Howells 1363cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1364cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1365cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1366cc53ce53SDavid Howells * being held. 1367cc53ce53SDavid Howells * 1368cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1369cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1370cc53ce53SDavid Howells * other than its daemon the right to mount on its 1371cc53ce53SDavid Howells * superstructure. 1372cc53ce53SDavid Howells * 1373cc53ce53SDavid Howells * The filesystem may sleep at this point. 1374cc53ce53SDavid Howells */ 1375cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1376cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1377cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1378ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 13791aed3e42SAl Viro path->dentry, false); 1380cc53ce53SDavid Howells if (ret < 0) 1381cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1382cc53ce53SDavid Howells } 1383cc53ce53SDavid Howells 1384cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1385cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1386cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1387cc53ce53SDavid Howells if (!mounted) 1388cc53ce53SDavid Howells break; 1389cc53ce53SDavid Howells dput(path->dentry); 1390cc53ce53SDavid Howells mntput(path->mnt); 1391cc53ce53SDavid Howells path->mnt = mounted; 1392cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1393cc53ce53SDavid Howells continue; 1394cc53ce53SDavid Howells } 1395cc53ce53SDavid Howells 1396cc53ce53SDavid Howells /* Don't handle automount points here */ 1397cc53ce53SDavid Howells break; 1398cc53ce53SDavid Howells } 1399cc53ce53SDavid Howells return 0; 1400cc53ce53SDavid Howells } 14014d359507SAl Viro EXPORT_SYMBOL(follow_down); 1402cc53ce53SDavid Howells 1403cc53ce53SDavid Howells /* 14049875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14059875cf80SDavid Howells */ 14069875cf80SDavid Howells static void follow_mount(struct path *path) 14079875cf80SDavid Howells { 14089875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14099875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14109875cf80SDavid Howells if (!mounted) 14119875cf80SDavid Howells break; 14129875cf80SDavid Howells dput(path->dentry); 14139875cf80SDavid Howells mntput(path->mnt); 14149875cf80SDavid Howells path->mnt = mounted; 14159875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14169875cf80SDavid Howells } 14179875cf80SDavid Howells } 14189875cf80SDavid Howells 1419eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1420eedf265aSEric W. Biederman { 1421eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1422eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1423eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1424eedf265aSEric W. Biederman dput(old); 1425eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1426eedf265aSEric W. Biederman return -ENOENT; 1427eedf265aSEric W. Biederman return 0; 1428eedf265aSEric W. Biederman } 1429eedf265aSEric W. Biederman 1430397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14311da177e4SLinus Torvalds { 14321da177e4SLinus Torvalds while(1) { 14332a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14342a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14351da177e4SLinus Torvalds break; 14361da177e4SLinus Torvalds } 14374ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1438eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1439eedf265aSEric W. Biederman if (ret) 1440eedf265aSEric W. Biederman return ret; 14411da177e4SLinus Torvalds break; 14421da177e4SLinus Torvalds } 14433088dd70SAl Viro if (!follow_up(&nd->path)) 14441da177e4SLinus Torvalds break; 14451da177e4SLinus Torvalds } 144679ed0226SAl Viro follow_mount(&nd->path); 144731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1448397d425dSEric W. Biederman return 0; 14491da177e4SLinus Torvalds } 14501da177e4SLinus Torvalds 14511da177e4SLinus Torvalds /* 1452bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1453bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1454bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1455baa03890SNick Piggin */ 1456e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1457e3c13928SAl Viro struct dentry *dir, 14586c51e513SAl Viro unsigned int flags) 1459baa03890SNick Piggin { 1460baa03890SNick Piggin struct dentry *dentry; 1461bad61189SMiklos Szeredi int error; 1462baa03890SNick Piggin 1463bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1464bad61189SMiklos Szeredi if (dentry) { 146539e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1466201f956eSAl Viro error = d_revalidate(dentry, flags); 1467bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146874ff0ffcSAl Viro if (!error) 14695542aa2fSEric W. Biederman d_invalidate(dentry); 1470bad61189SMiklos Szeredi dput(dentry); 147174ff0ffcSAl Viro return ERR_PTR(error); 1472bad61189SMiklos Szeredi } 1473bad61189SMiklos Szeredi } 1474bad61189SMiklos Szeredi } 1475baa03890SNick Piggin return dentry; 1476baa03890SNick Piggin } 1477baa03890SNick Piggin 1478baa03890SNick Piggin /* 147913a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 148013a2c3beSJ. Bruce Fields * unhashed. 1481bad61189SMiklos Szeredi * 1482bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 148344396f4bSJosef Bacik */ 1484bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 148572bd866aSAl Viro unsigned int flags) 148644396f4bSJosef Bacik { 148744396f4bSJosef Bacik struct dentry *old; 148844396f4bSJosef Bacik 148944396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1490bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1491e188dc02SMiklos Szeredi dput(dentry); 149244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1493e188dc02SMiklos Szeredi } 149444396f4bSJosef Bacik 149572bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 149644396f4bSJosef Bacik if (unlikely(old)) { 149744396f4bSJosef Bacik dput(dentry); 149844396f4bSJosef Bacik dentry = old; 149944396f4bSJosef Bacik } 150044396f4bSJosef Bacik return dentry; 150144396f4bSJosef Bacik } 150244396f4bSJosef Bacik 1503e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 150472bd866aSAl Viro struct dentry *base, unsigned int flags) 1505a3255546SAl Viro { 15066c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1507a3255546SAl Viro 15086c51e513SAl Viro if (dentry) 1509a3255546SAl Viro return dentry; 1510bad61189SMiklos Szeredi 15116c51e513SAl Viro dentry = d_alloc(base, name); 15126c51e513SAl Viro if (unlikely(!dentry)) 15136c51e513SAl Viro return ERR_PTR(-ENOMEM); 15146c51e513SAl Viro 151572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1516a3255546SAl Viro } 1517a3255546SAl Viro 1518e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1519254cf582SAl Viro struct path *path, struct inode **inode, 1520254cf582SAl Viro unsigned *seqp) 15211da177e4SLinus Torvalds { 15224ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 152331e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15245a18fff2SAl Viro int status = 1; 15259875cf80SDavid Howells int err; 15269875cf80SDavid Howells 15273cac260aSAl Viro /* 1528b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15295d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15305d0f49c1SAl Viro * going to fall back to non-racy lookup. 1531b04f784eSNick Piggin */ 153231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 153331e6b01fSNick Piggin unsigned seq; 1534766c4cbfSAl Viro bool negative; 1535da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15365d0f49c1SAl Viro if (unlikely(!dentry)) { 15375d0f49c1SAl Viro if (unlazy_walk(nd, NULL, 0)) 15385d0f49c1SAl Viro return -ECHILD; 1539e9742b53SAl Viro return 0; 15405d0f49c1SAl Viro } 15415a18fff2SAl Viro 154212f8ad4bSLinus Torvalds /* 154312f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 154412f8ad4bSLinus Torvalds * the dentry name information from lookup. 154512f8ad4bSLinus Torvalds */ 154663afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1547766c4cbfSAl Viro negative = d_is_negative(dentry); 15485d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 154912f8ad4bSLinus Torvalds return -ECHILD; 155012f8ad4bSLinus Torvalds 155112f8ad4bSLinus Torvalds /* 155212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 155312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 155412f8ad4bSLinus Torvalds * 155512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 155612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 155712f8ad4bSLinus Torvalds */ 15585d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 155931e6b01fSNick Piggin return -ECHILD; 15605a18fff2SAl Viro 1561254cf582SAl Viro *seqp = seq; 15625d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15634ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15645a18fff2SAl Viro if (unlikely(status <= 0)) { 15655d0f49c1SAl Viro if (unlazy_walk(nd, dentry, seq)) 15665d0f49c1SAl Viro return -ECHILD; 15675d0f49c1SAl Viro if (status == -ECHILD) 15685d0f49c1SAl Viro status = d_revalidate(dentry, nd->flags); 15695d0f49c1SAl Viro } else { 1570daf3761cSTrond Myklebust /* 1571daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1572daf3761cSTrond Myklebust * case that drops it. 1573daf3761cSTrond Myklebust */ 15745d0f49c1SAl Viro if (unlikely(negative)) 1575daf3761cSTrond Myklebust return -ENOENT; 157631e6b01fSNick Piggin path->mnt = mnt; 157731e6b01fSNick Piggin path->dentry = dentry; 1578254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1579e9742b53SAl Viro return 1; 1580254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 15815a18fff2SAl Viro return -ECHILD; 15825d0f49c1SAl Viro } 15835a18fff2SAl Viro } else { 1584e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 158581e6f520SAl Viro if (unlikely(!dentry)) 1586e9742b53SAl Viro return 0; 15875d0f49c1SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 15884ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15895d0f49c1SAl Viro } 15905a18fff2SAl Viro if (unlikely(status <= 0)) { 1591e9742b53SAl Viro if (!status) 15925d0f49c1SAl Viro d_invalidate(dentry); 15935a18fff2SAl Viro dput(dentry); 15945a18fff2SAl Viro return status; 15955a18fff2SAl Viro } 1596766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1597766c4cbfSAl Viro dput(dentry); 1598766c4cbfSAl Viro return -ENOENT; 1599766c4cbfSAl Viro } 16005d0f49c1SAl Viro 16011da177e4SLinus Torvalds path->mnt = mnt; 16021da177e4SLinus Torvalds path->dentry = dentry; 1603756daf26SNeilBrown err = follow_managed(path, nd); 1604e9742b53SAl Viro if (likely(err > 0)) 160563afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16068402752eSAl Viro return err; 1607697f514dSMiklos Szeredi } 1608697f514dSMiklos Szeredi 1609697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1610e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1611e3c13928SAl Viro struct dentry *dir, 1612e3c13928SAl Viro unsigned int flags) 1613697f514dSMiklos Szeredi { 161494bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16151936386eSAl Viro struct inode *inode = dir->d_inode; 1616d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16171936386eSAl Viro 16189902af79SAl Viro inode_lock_shared(inode); 16191936386eSAl Viro /* Don't go there if it's already dead */ 162094bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 162194bdd655SAl Viro goto out; 162294bdd655SAl Viro again: 1623d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 162494bdd655SAl Viro if (IS_ERR(dentry)) 162594bdd655SAl Viro goto out; 162694bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1627949a852eSAl Viro if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && 1628949a852eSAl Viro !(flags & LOOKUP_NO_REVAL)) { 1629949a852eSAl Viro int error = d_revalidate(dentry, flags); 1630949a852eSAl Viro if (unlikely(error <= 0)) { 163194bdd655SAl Viro if (!error) { 1632949a852eSAl Viro d_invalidate(dentry); 1633949a852eSAl Viro dput(dentry); 163494bdd655SAl Viro goto again; 163594bdd655SAl Viro } 163694bdd655SAl Viro dput(dentry); 1637949a852eSAl Viro dentry = ERR_PTR(error); 1638949a852eSAl Viro } 1639949a852eSAl Viro } 164094bdd655SAl Viro } else { 16411936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 164285c7f810SAl Viro d_lookup_done(dentry); 16431936386eSAl Viro if (unlikely(old)) { 16441936386eSAl Viro dput(dentry); 16451936386eSAl Viro dentry = old; 1646949a852eSAl Viro } 1647949a852eSAl Viro } 164894bdd655SAl Viro out: 16499902af79SAl Viro inode_unlock_shared(inode); 1650e3c13928SAl Viro return dentry; 16511da177e4SLinus Torvalds } 16521da177e4SLinus Torvalds 165352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 165452094c8aSAl Viro { 165552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16564ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 165752094c8aSAl Viro if (err != -ECHILD) 165852094c8aSAl Viro return err; 16596e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 166052094c8aSAl Viro return -ECHILD; 166152094c8aSAl Viro } 16624ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 166352094c8aSAl Viro } 166452094c8aSAl Viro 16659856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16669856fa1bSAl Viro { 16679856fa1bSAl Viro if (type == LAST_DOTDOT) { 16689e6697e2SAl Viro if (!nd->root.mnt) 16699e6697e2SAl Viro set_root(nd); 16709856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 167170291aecSAl Viro return follow_dotdot_rcu(nd); 16729856fa1bSAl Viro } else 1673397d425dSEric W. Biederman return follow_dotdot(nd); 16749856fa1bSAl Viro } 16759856fa1bSAl Viro return 0; 16769856fa1bSAl Viro } 16779856fa1bSAl Viro 1678181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1679181548c0SAl Viro struct inode *inode, unsigned seq) 1680d63ff28fSAl Viro { 1681626de996SAl Viro int error; 16821cf2665bSAl Viro struct saved *last; 1683756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1684626de996SAl Viro path_to_nameidata(link, nd); 1685626de996SAl Viro return -ELOOP; 1686626de996SAl Viro } 1687bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1688cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1689cd179f44SAl Viro mntget(link->mnt); 16907973387aSAl Viro } 1691626de996SAl Viro error = nd_alloc_stack(nd); 1692626de996SAl Viro if (unlikely(error)) { 1693bc40aee0SAl Viro if (error == -ECHILD) { 1694bc40aee0SAl Viro if (unlikely(unlazy_link(nd, link, seq))) 1695bc40aee0SAl Viro return -ECHILD; 1696bc40aee0SAl Viro error = nd_alloc_stack(nd); 1697bc40aee0SAl Viro } 1698bc40aee0SAl Viro if (error) { 1699cd179f44SAl Viro path_put(link); 1700626de996SAl Viro return error; 1701626de996SAl Viro } 1702bc40aee0SAl Viro } 1703626de996SAl Viro 1704ab104923SAl Viro last = nd->stack + nd->depth++; 17051cf2665bSAl Viro last->link = *link; 1706fceef393SAl Viro clear_delayed_call(&last->done); 1707fceef393SAl Viro nd->link_inode = inode; 17080450b2d1SAl Viro last->seq = seq; 1709d63ff28fSAl Viro return 1; 1710d63ff28fSAl Viro } 1711d63ff28fSAl Viro 17123ddcd056SLinus Torvalds /* 17133ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17143ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17153ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17163ddcd056SLinus Torvalds * for the common case. 17173ddcd056SLinus Torvalds */ 1718254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1719181548c0SAl Viro int follow, 1720181548c0SAl Viro struct inode *inode, unsigned seq) 17213ddcd056SLinus Torvalds { 1722d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1723d63ff28fSAl Viro return 0; 1724d63ff28fSAl Viro if (!follow) 1725d63ff28fSAl Viro return 0; 1726a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1727a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1728a7f77542SAl Viro if (read_seqcount_retry(&link->dentry->d_seq, seq)) 1729a7f77542SAl Viro return -ECHILD; 1730a7f77542SAl Viro } 1731181548c0SAl Viro return pick_link(nd, link, inode, seq); 17323ddcd056SLinus Torvalds } 17333ddcd056SLinus Torvalds 17344693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 17354693a547SAl Viro 17364693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1737ce57dfc1SAl Viro { 1738caa85634SAl Viro struct path path; 1739ce57dfc1SAl Viro struct inode *inode; 1740254cf582SAl Viro unsigned seq; 1741ce57dfc1SAl Viro int err; 1742ce57dfc1SAl Viro /* 1743ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1744ce57dfc1SAl Viro * to be able to know about the current root directory and 1745ce57dfc1SAl Viro * parent relationships. 1746ce57dfc1SAl Viro */ 17474693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17484693a547SAl Viro err = handle_dots(nd, nd->last_type); 17494693a547SAl Viro if (flags & WALK_PUT) 17504693a547SAl Viro put_link(nd); 17514693a547SAl Viro return err; 17524693a547SAl Viro } 1753254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1754e9742b53SAl Viro if (unlikely(err <= 0)) { 1755697f514dSMiklos Szeredi if (err < 0) 1756f0a9ba70SAl Viro return err; 1757e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1758e3c13928SAl Viro nd->flags); 1759e3c13928SAl Viro if (IS_ERR(path.dentry)) 1760e3c13928SAl Viro return PTR_ERR(path.dentry); 17617500c38aSAl Viro 1762e3c13928SAl Viro path.mnt = nd->path.mnt; 1763e3c13928SAl Viro err = follow_managed(&path, nd); 1764e3c13928SAl Viro if (unlikely(err < 0)) 1765f0a9ba70SAl Viro return err; 1766697f514dSMiklos Szeredi 17677500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17687500c38aSAl Viro path_to_nameidata(&path, nd); 17697500c38aSAl Viro return -ENOENT; 17707500c38aSAl Viro } 17717500c38aSAl Viro 1772254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1773d4565649SAl Viro inode = d_backing_inode(path.dentry); 1774766c4cbfSAl Viro } 1775697f514dSMiklos Szeredi 17764693a547SAl Viro if (flags & WALK_PUT) 17774693a547SAl Viro put_link(nd); 1778181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1779d63ff28fSAl Viro if (unlikely(err)) 1780d63ff28fSAl Viro return err; 1781caa85634SAl Viro path_to_nameidata(&path, nd); 1782ce57dfc1SAl Viro nd->inode = inode; 1783254cf582SAl Viro nd->seq = seq; 1784ce57dfc1SAl Viro return 0; 1785ce57dfc1SAl Viro } 1786ce57dfc1SAl Viro 17871da177e4SLinus Torvalds /* 1788bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1789bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1790bfcfaa77SLinus Torvalds * 1791bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1792bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1793bfcfaa77SLinus Torvalds * fast. 1794bfcfaa77SLinus Torvalds * 1795bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1796bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1797bfcfaa77SLinus Torvalds * crossing operation. 1798bfcfaa77SLinus Torvalds * 1799bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1800bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1801bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1802bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1803bfcfaa77SLinus Torvalds */ 1804bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1805bfcfaa77SLinus Torvalds 1806f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1807bfcfaa77SLinus Torvalds 1808468a9428SGeorge Spelvin #ifdef HASH_MIX 1809bfcfaa77SLinus Torvalds 1810468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1811468a9428SGeorge Spelvin 1812468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18132a18da7aSGeorge Spelvin /* 18142a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18152a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18162a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18172a18da7aSGeorge Spelvin * and no temporaries. 18182a18da7aSGeorge Spelvin * 18192a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18202a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18212a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18222a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18232a18da7aSGeorge Spelvin * 18242a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18252a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18262a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18272a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18282a18da7aSGeorge Spelvin * 18292a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18302a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18312a18da7aSGeorge Spelvin * toggling any given output bit. 18322a18da7aSGeorge Spelvin * 18332a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18342a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18352a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18362a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18372a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18382a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18392a18da7aSGeorge Spelvin * Perfect: 8192 258048 18402a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18412a18da7aSGeorge Spelvin */ 18422a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18432a18da7aSGeorge Spelvin ( x ^= (a), \ 18442a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18452a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18462a18da7aSGeorge Spelvin y *= 9 ) 1847bfcfaa77SLinus Torvalds 18480fed3ac8SGeorge Spelvin /* 18492a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18502a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18512a18da7aSGeorge Spelvin * work done before the hash value is used. 18520fed3ac8SGeorge Spelvin */ 18532a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18540fed3ac8SGeorge Spelvin { 18552a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18562a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18572a18da7aSGeorge Spelvin return y >> 32; 18580fed3ac8SGeorge Spelvin } 18590fed3ac8SGeorge Spelvin 1860bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1861bfcfaa77SLinus Torvalds 18622a18da7aSGeorge Spelvin /* 18632a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18642a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18652a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18662a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18672a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18682a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18692a18da7aSGeorge Spelvin * Perfect: 2048 31744 18702a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18712a18da7aSGeorge Spelvin */ 18722a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18732a18da7aSGeorge Spelvin ( x ^= (a), \ 18742a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18752a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18762a18da7aSGeorge Spelvin y *= 9 ) 1877bfcfaa77SLinus Torvalds 18782a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18790fed3ac8SGeorge Spelvin { 18802a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18812a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18820fed3ac8SGeorge Spelvin } 18830fed3ac8SGeorge Spelvin 1884bfcfaa77SLinus Torvalds #endif 1885bfcfaa77SLinus Torvalds 18862a18da7aSGeorge Spelvin /* 18872a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18882a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18892a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18902a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18912a18da7aSGeorge Spelvin * finds the delimiter after the name. 18922a18da7aSGeorge Spelvin */ 1893fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 1894bfcfaa77SLinus Torvalds { 18952a18da7aSGeorge Spelvin unsigned long a, x = 0, y = 0; 1896bfcfaa77SLinus Torvalds 1897bfcfaa77SLinus Torvalds for (;;) { 1898fcfd2fbfSGeorge Spelvin if (!len) 1899fcfd2fbfSGeorge Spelvin goto done; 1900e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1901bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1902bfcfaa77SLinus Torvalds break; 19032a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1904bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1905bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1906bfcfaa77SLinus Torvalds } 19072a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1908bfcfaa77SLinus Torvalds done: 19092a18da7aSGeorge Spelvin return fold_hash(x, y); 1910bfcfaa77SLinus Torvalds } 1911bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1912bfcfaa77SLinus Torvalds 1913fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1914fcfd2fbfSGeorge Spelvin u64 hashlen_string(const char *name) 1915fcfd2fbfSGeorge Spelvin { 19162a18da7aSGeorge Spelvin unsigned long a = 0, x = 0, y = 0, adata, mask, len; 1917fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1918fcfd2fbfSGeorge Spelvin 1919fcfd2fbfSGeorge Spelvin len = -sizeof(unsigned long); 1920fcfd2fbfSGeorge Spelvin do { 19212a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1922fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 1923fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1924fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1925fcfd2fbfSGeorge Spelvin 1926fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1927fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19282a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1929fcfd2fbfSGeorge Spelvin 19302a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1931fcfd2fbfSGeorge Spelvin } 1932fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1933fcfd2fbfSGeorge Spelvin 1934bfcfaa77SLinus Torvalds /* 1935bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1936d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1937bfcfaa77SLinus Torvalds */ 1938d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1939bfcfaa77SLinus Torvalds { 19402a18da7aSGeorge Spelvin unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len; 194136126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1942bfcfaa77SLinus Torvalds 1943bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1944bfcfaa77SLinus Torvalds do { 19452a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1946bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1947e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 194836126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 194936126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1950bfcfaa77SLinus Torvalds 195136126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 195236126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 195336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19542a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 195536126f8fSLinus Torvalds 19562a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1957bfcfaa77SLinus Torvalds } 1958bfcfaa77SLinus Torvalds 19592a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1960bfcfaa77SLinus Torvalds 1961fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 1962fcfd2fbfSGeorge Spelvin unsigned int full_name_hash(const char *name, unsigned int len) 19630145acc2SLinus Torvalds { 19640145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 19650145acc2SLinus Torvalds while (len--) 1966fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19670145acc2SLinus Torvalds return end_name_hash(hash); 19680145acc2SLinus Torvalds } 1969ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19700145acc2SLinus Torvalds 1971fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 1972f2a031b6SGeorge Spelvin u64 hashlen_string(const char *name) 1973fcfd2fbfSGeorge Spelvin { 1974fcfd2fbfSGeorge Spelvin unsigned long hash = init_name_hash(); 1975fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1976fcfd2fbfSGeorge Spelvin 1977fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1978e0ab7af9SGeorge Spelvin while (c) { 1979fcfd2fbfSGeorge Spelvin len++; 1980fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1981fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1982e0ab7af9SGeorge Spelvin } 1983fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1984fcfd2fbfSGeorge Spelvin } 1985f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1986fcfd2fbfSGeorge Spelvin 19873ddcd056SLinus Torvalds /* 1988200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1989200e9ef7SLinus Torvalds * one character. 1990200e9ef7SLinus Torvalds */ 1991d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1992200e9ef7SLinus Torvalds { 1993200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1994200e9ef7SLinus Torvalds unsigned long len = 0, c; 1995200e9ef7SLinus Torvalds 1996200e9ef7SLinus Torvalds c = (unsigned char)*name; 1997200e9ef7SLinus Torvalds do { 1998200e9ef7SLinus Torvalds len++; 1999200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2000200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2001200e9ef7SLinus Torvalds } while (c && c != '/'); 2002d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2003200e9ef7SLinus Torvalds } 2004200e9ef7SLinus Torvalds 2005bfcfaa77SLinus Torvalds #endif 2006bfcfaa77SLinus Torvalds 2007200e9ef7SLinus Torvalds /* 20081da177e4SLinus Torvalds * Name resolution. 2009ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2010ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20111da177e4SLinus Torvalds * 2012ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2013ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20141da177e4SLinus Torvalds */ 20156de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20161da177e4SLinus Torvalds { 20171da177e4SLinus Torvalds int err; 20181da177e4SLinus Torvalds 20191da177e4SLinus Torvalds while (*name=='/') 20201da177e4SLinus Torvalds name++; 20211da177e4SLinus Torvalds if (!*name) 20229e18f10aSAl Viro return 0; 20231da177e4SLinus Torvalds 20241da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20251da177e4SLinus Torvalds for(;;) { 2026d6bb3e90SLinus Torvalds u64 hash_len; 2027fe479a58SAl Viro int type; 20281da177e4SLinus Torvalds 202952094c8aSAl Viro err = may_lookup(nd); 20301da177e4SLinus Torvalds if (err) 20313595e234SAl Viro return err; 20321da177e4SLinus Torvalds 2033d6bb3e90SLinus Torvalds hash_len = hash_name(name); 20341da177e4SLinus Torvalds 2035fe479a58SAl Viro type = LAST_NORM; 2036d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2037fe479a58SAl Viro case 2: 2038200e9ef7SLinus Torvalds if (name[1] == '.') { 2039fe479a58SAl Viro type = LAST_DOTDOT; 204016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 204116c2cd71SAl Viro } 2042fe479a58SAl Viro break; 2043fe479a58SAl Viro case 1: 2044fe479a58SAl Viro type = LAST_DOT; 2045fe479a58SAl Viro } 20465a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20475a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 204816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20495a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2050a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2051da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20525a202bcdSAl Viro if (err < 0) 20533595e234SAl Viro return err; 2054d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2055d6bb3e90SLinus Torvalds name = this.name; 20565a202bcdSAl Viro } 20575a202bcdSAl Viro } 2058fe479a58SAl Viro 2059d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2060d6bb3e90SLinus Torvalds nd->last.name = name; 20615f4a6a69SAl Viro nd->last_type = type; 20625f4a6a69SAl Viro 2063d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2064d6bb3e90SLinus Torvalds if (!*name) 2065bdf6cbf1SAl Viro goto OK; 2066200e9ef7SLinus Torvalds /* 2067200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2068200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2069200e9ef7SLinus Torvalds */ 2070200e9ef7SLinus Torvalds do { 2071d6bb3e90SLinus Torvalds name++; 2072d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20738620c238SAl Viro if (unlikely(!*name)) { 20748620c238SAl Viro OK: 2075368ee9baSAl Viro /* pathname body, done */ 20768620c238SAl Viro if (!nd->depth) 20778620c238SAl Viro return 0; 20788620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2079368ee9baSAl Viro /* trailing symlink, done */ 20808620c238SAl Viro if (!name) 20818620c238SAl Viro return 0; 20828620c238SAl Viro /* last component of nested symlink */ 20834693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 20848620c238SAl Viro } else { 20854693a547SAl Viro err = walk_component(nd, WALK_GET); 20868620c238SAl Viro } 2087ce57dfc1SAl Viro if (err < 0) 20883595e234SAl Viro return err; 2089fe479a58SAl Viro 2090ce57dfc1SAl Viro if (err) { 2091626de996SAl Viro const char *s = get_link(nd); 20925a460275SAl Viro 2093a1c83681SViresh Kumar if (IS_ERR(s)) 20943595e234SAl Viro return PTR_ERR(s); 2095172a39a0SAl Viro err = 0; 209612b09578SAl Viro if (unlikely(!s)) { 209712b09578SAl Viro /* jumped */ 2098b9ff4429SAl Viro put_link(nd); 209912b09578SAl Viro } else { 2100071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 210132cd7468SAl Viro name = s; 21029e18f10aSAl Viro continue; 210348c8b0c5SAl Viro } 210431e6b01fSNick Piggin } 210597242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 210697242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 210797242f99SAl Viro if (unlazy_walk(nd, NULL, 0)) 210897242f99SAl Viro return -ECHILD; 210997242f99SAl Viro } 21103595e234SAl Viro return -ENOTDIR; 21115f4a6a69SAl Viro } 2112ce57dfc1SAl Viro } 211397242f99SAl Viro } 21141da177e4SLinus Torvalds 2115c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 211631e6b01fSNick Piggin { 211731e6b01fSNick Piggin int retval = 0; 2118c8a53ee5SAl Viro const char *s = nd->name->name; 211931e6b01fSNick Piggin 212031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2121980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 212231e6b01fSNick Piggin nd->depth = 0; 21235b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2124b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2125b18825a7SDavid Howells struct inode *inode = root->d_inode; 2126fd2f7cb5SAl Viro if (*s) { 212744b1d530SMiklos Szeredi if (!d_can_lookup(root)) 2128368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21295b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 21305b6ca027SAl Viro if (retval) 2131368ee9baSAl Viro return ERR_PTR(retval); 213273d049a4SAl Viro } 21335b6ca027SAl Viro nd->path = nd->root; 21345b6ca027SAl Viro nd->inode = inode; 21355b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21368b61e74fSAl Viro rcu_read_lock(); 21375b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21388f47a016SAl Viro nd->root_seq = nd->seq; 213948a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21405b6ca027SAl Viro } else { 21415b6ca027SAl Viro path_get(&nd->path); 21425b6ca027SAl Viro } 2143368ee9baSAl Viro return s; 21445b6ca027SAl Viro } 21455b6ca027SAl Viro 214631e6b01fSNick Piggin nd->root.mnt = NULL; 2147248fb5b9SAl Viro nd->path.mnt = NULL; 2148248fb5b9SAl Viro nd->path.dentry = NULL; 214931e6b01fSNick Piggin 215048a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2151fd2f7cb5SAl Viro if (*s == '/') { 21529e6697e2SAl Viro if (flags & LOOKUP_RCU) 21538b61e74fSAl Viro rcu_read_lock(); 2154e41f7d4eSAl Viro set_root(nd); 2155248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2156ef55d917SAl Viro return s; 2157ef55d917SAl Viro nd->root.mnt = NULL; 2158ef55d917SAl Viro rcu_read_unlock(); 2159ef55d917SAl Viro return ERR_PTR(-ECHILD); 2160c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2161e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 216231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2163c28cc364SNick Piggin unsigned seq; 216431e6b01fSNick Piggin 21658b61e74fSAl Viro rcu_read_lock(); 216631e6b01fSNick Piggin 2167c28cc364SNick Piggin do { 2168c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 216931e6b01fSNick Piggin nd->path = fs->pwd; 2170ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2171c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2172c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2173e41f7d4eSAl Viro } else { 2174e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2175ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2176e41f7d4eSAl Viro } 2177ef55d917SAl Viro return s; 217831e6b01fSNick Piggin } else { 2179582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2180c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 218131e6b01fSNick Piggin struct dentry *dentry; 218231e6b01fSNick Piggin 21832903ff01SAl Viro if (!f.file) 2184368ee9baSAl Viro return ERR_PTR(-EBADF); 218531e6b01fSNick Piggin 21862903ff01SAl Viro dentry = f.file->f_path.dentry; 218731e6b01fSNick Piggin 2188fd2f7cb5SAl Viro if (*s) { 218944b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21902903ff01SAl Viro fdput(f); 2191368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2192f52e0c11SAl Viro } 21932903ff01SAl Viro } 21942903ff01SAl Viro 21952903ff01SAl Viro nd->path = f.file->f_path; 2196e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 21978b61e74fSAl Viro rcu_read_lock(); 219834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 219934a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22005590ff0dSUlrich Drepper } else { 22012903ff01SAl Viro path_get(&nd->path); 220234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22031da177e4SLinus Torvalds } 220434a26b99SAl Viro fdput(f); 2205368ee9baSAl Viro return s; 2206e41f7d4eSAl Viro } 22079b4a9b14SAl Viro } 22089b4a9b14SAl Viro 22093bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 221095fa25d9SAl Viro { 221195fa25d9SAl Viro const char *s; 2212fec2fa24SAl Viro int error = may_follow_link(nd); 2213deb106c6SAl Viro if (unlikely(error)) 22143bdba28bSAl Viro return ERR_PTR(error); 221595fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2216fab51e8aSAl Viro nd->stack[0].name = NULL; 22173b2e7f75SAl Viro s = get_link(nd); 2218deb106c6SAl Viro return s ? s : ""; 221995fa25d9SAl Viro } 222095fa25d9SAl Viro 2221caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2222bd92d7feSAl Viro { 2223bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2224bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2225bd92d7feSAl Viro 2226bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2227deb106c6SAl Viro return walk_component(nd, 22284693a547SAl Viro nd->flags & LOOKUP_FOLLOW 22294693a547SAl Viro ? nd->depth 22304693a547SAl Viro ? WALK_PUT | WALK_GET 22314693a547SAl Viro : WALK_GET 22324693a547SAl Viro : 0); 2233bd92d7feSAl Viro } 2234bd92d7feSAl Viro 22359b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2236c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22379b4a9b14SAl Viro { 2238c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2239bd92d7feSAl Viro int err; 224031e6b01fSNick Piggin 2241368ee9baSAl Viro if (IS_ERR(s)) 2242368ee9baSAl Viro return PTR_ERR(s); 22433bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22443bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22453bdba28bSAl Viro s = trailing_symlink(nd); 22463bdba28bSAl Viro if (IS_ERR(s)) { 22473bdba28bSAl Viro err = PTR_ERR(s); 22486d7b5aaeSAl Viro break; 2249bd92d7feSAl Viro } 2250bd92d7feSAl Viro } 22519f1fafeeSAl Viro if (!err) 22529f1fafeeSAl Viro err = complete_walk(nd); 2253bd92d7feSAl Viro 2254deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2255deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2256bd23a539SAl Viro err = -ENOTDIR; 2257625b6d10SAl Viro if (!err) { 2258625b6d10SAl Viro *path = nd->path; 2259625b6d10SAl Viro nd->path.mnt = NULL; 2260625b6d10SAl Viro nd->path.dentry = NULL; 2261625b6d10SAl Viro } 2262deb106c6SAl Viro terminate_walk(nd); 2263bd92d7feSAl Viro return err; 226431e6b01fSNick Piggin } 226531e6b01fSNick Piggin 2266625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22679ad1aaa6SAl Viro struct path *path, struct path *root) 2268873f1eedSJeff Layton { 2269894bc8c4SAl Viro int retval; 22709883d185SAl Viro struct nameidata nd; 2271abc9f5beSAl Viro if (IS_ERR(name)) 2272abc9f5beSAl Viro return PTR_ERR(name); 22739ad1aaa6SAl Viro if (unlikely(root)) { 22749ad1aaa6SAl Viro nd.root = *root; 22759ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 22769ad1aaa6SAl Viro } 22779883d185SAl Viro set_nameidata(&nd, dfd, name); 2278c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2279873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2280c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2281873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2282c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2283873f1eedSJeff Layton 2284873f1eedSJeff Layton if (likely(!retval)) 2285625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 22869883d185SAl Viro restore_nameidata(); 2287e4bd1c1aSAl Viro putname(name); 2288873f1eedSJeff Layton return retval; 2289873f1eedSJeff Layton } 2290873f1eedSJeff Layton 22918bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2292c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2293391172c4SAl Viro struct path *parent) 22948bcb77faSAl Viro { 2295c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2296368ee9baSAl Viro int err; 2297368ee9baSAl Viro if (IS_ERR(s)) 2298368ee9baSAl Viro return PTR_ERR(s); 2299368ee9baSAl Viro err = link_path_walk(s, nd); 23008bcb77faSAl Viro if (!err) 23018bcb77faSAl Viro err = complete_walk(nd); 2302391172c4SAl Viro if (!err) { 2303391172c4SAl Viro *parent = nd->path; 2304391172c4SAl Viro nd->path.mnt = NULL; 2305391172c4SAl Viro nd->path.dentry = NULL; 2306391172c4SAl Viro } 2307deb106c6SAl Viro terminate_walk(nd); 23088bcb77faSAl Viro return err; 23098bcb77faSAl Viro } 23108bcb77faSAl Viro 23115c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2312391172c4SAl Viro unsigned int flags, struct path *parent, 2313391172c4SAl Viro struct qstr *last, int *type) 23148bcb77faSAl Viro { 23158bcb77faSAl Viro int retval; 23169883d185SAl Viro struct nameidata nd; 23178bcb77faSAl Viro 23185c31b6ceSAl Viro if (IS_ERR(name)) 23195c31b6ceSAl Viro return name; 23209883d185SAl Viro set_nameidata(&nd, dfd, name); 2321c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23228bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2323c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23248bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2325c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2326391172c4SAl Viro if (likely(!retval)) { 2327391172c4SAl Viro *last = nd.last; 2328391172c4SAl Viro *type = nd.last_type; 2329391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23305c31b6ceSAl Viro } else { 23315c31b6ceSAl Viro putname(name); 23325c31b6ceSAl Viro name = ERR_PTR(retval); 2333391172c4SAl Viro } 23349883d185SAl Viro restore_nameidata(); 23355c31b6ceSAl Viro return name; 23368bcb77faSAl Viro } 23378bcb77faSAl Viro 233879714f72SAl Viro /* does lookup, returns the object with parent locked */ 233979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23405590ff0dSUlrich Drepper { 23415c31b6ceSAl Viro struct filename *filename; 23425c31b6ceSAl Viro struct dentry *d; 2343391172c4SAl Viro struct qstr last; 2344391172c4SAl Viro int type; 234551689104SPaul Moore 23465c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23475c31b6ceSAl Viro &last, &type); 234851689104SPaul Moore if (IS_ERR(filename)) 234951689104SPaul Moore return ERR_CAST(filename); 23505c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2351391172c4SAl Viro path_put(path); 23525c31b6ceSAl Viro putname(filename); 23535c31b6ceSAl Viro return ERR_PTR(-EINVAL); 235479714f72SAl Viro } 23555955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2356391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 235779714f72SAl Viro if (IS_ERR(d)) { 23585955102cSAl Viro inode_unlock(path->dentry->d_inode); 2359391172c4SAl Viro path_put(path); 236079714f72SAl Viro } 236151689104SPaul Moore putname(filename); 236279714f72SAl Viro return d; 23635590ff0dSUlrich Drepper } 23645590ff0dSUlrich Drepper 2365d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2366d1811465SAl Viro { 2367abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2368abc9f5beSAl Viro flags, path, NULL); 2369d1811465SAl Viro } 23704d359507SAl Viro EXPORT_SYMBOL(kern_path); 2371d1811465SAl Viro 237216f18200SJosef 'Jeff' Sipek /** 237316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 237416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 237516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 237616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 237716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2378e0a01249SAl Viro * @path: pointer to struct path to fill 237916f18200SJosef 'Jeff' Sipek */ 238016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 238116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2382e0a01249SAl Viro struct path *path) 238316f18200SJosef 'Jeff' Sipek { 23849ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 23859ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2386abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2387abc9f5beSAl Viro flags , path, &root); 238816f18200SJosef 'Jeff' Sipek } 23894d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 239016f18200SJosef 'Jeff' Sipek 2391eead1911SChristoph Hellwig /** 23923c9fe8cdSMiklos Szeredi * lookup_hash - lookup single pathname component on already hashed name 23933c9fe8cdSMiklos Szeredi * @name: name and hash to lookup 23943c9fe8cdSMiklos Szeredi * @base: base directory to lookup from 23953c9fe8cdSMiklos Szeredi * 23963c9fe8cdSMiklos Szeredi * The name must have been verified and hashed (see lookup_one_len()). Using 23973c9fe8cdSMiklos Szeredi * this after just full_name_hash() is unsafe. 23983c9fe8cdSMiklos Szeredi * 23993c9fe8cdSMiklos Szeredi * This function also doesn't check for search permission on base directory. 24003c9fe8cdSMiklos Szeredi * 24013c9fe8cdSMiklos Szeredi * Use lookup_one_len_unlocked() instead, unless you really know what you are 24023c9fe8cdSMiklos Szeredi * doing. 24033c9fe8cdSMiklos Szeredi * 24043c9fe8cdSMiklos Szeredi * Do not hold i_mutex; this helper takes i_mutex if necessary. 24053c9fe8cdSMiklos Szeredi */ 24063c9fe8cdSMiklos Szeredi struct dentry *lookup_hash(const struct qstr *name, struct dentry *base) 24073c9fe8cdSMiklos Szeredi { 24083c9fe8cdSMiklos Szeredi struct dentry *ret; 24093c9fe8cdSMiklos Szeredi 24103c9fe8cdSMiklos Szeredi ret = lookup_dcache(name, base, 0); 24113c9fe8cdSMiklos Szeredi if (!ret) 24123c9fe8cdSMiklos Szeredi ret = lookup_slow(name, base, 0); 24133c9fe8cdSMiklos Szeredi 24143c9fe8cdSMiklos Szeredi return ret; 24153c9fe8cdSMiklos Szeredi } 24163c9fe8cdSMiklos Szeredi EXPORT_SYMBOL(lookup_hash); 24173c9fe8cdSMiklos Szeredi 24183c9fe8cdSMiklos Szeredi /** 2419a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2420eead1911SChristoph Hellwig * @name: pathname component to lookup 2421eead1911SChristoph Hellwig * @base: base directory to lookup from 2422eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2423eead1911SChristoph Hellwig * 2424a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24259e7543e9SAl Viro * not be called by generic code. 2426bbddca8eSNeilBrown * 2427bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2428eead1911SChristoph Hellwig */ 2429057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2430057f6c01SJames Morris { 2431057f6c01SJames Morris struct qstr this; 24326a96ba54SAl Viro unsigned int c; 2433cda309deSMiklos Szeredi int err; 2434057f6c01SJames Morris 24355955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24362f9092e1SDavid Woodhouse 24376a96ba54SAl Viro this.name = name; 24386a96ba54SAl Viro this.len = len; 24390145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 24406a96ba54SAl Viro if (!len) 24416a96ba54SAl Viro return ERR_PTR(-EACCES); 24426a96ba54SAl Viro 244321d8a15aSAl Viro if (unlikely(name[0] == '.')) { 244421d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 244521d8a15aSAl Viro return ERR_PTR(-EACCES); 244621d8a15aSAl Viro } 244721d8a15aSAl Viro 24486a96ba54SAl Viro while (len--) { 24496a96ba54SAl Viro c = *(const unsigned char *)name++; 24506a96ba54SAl Viro if (c == '/' || c == '\0') 24516a96ba54SAl Viro return ERR_PTR(-EACCES); 24526a96ba54SAl Viro } 24535a202bcdSAl Viro /* 24545a202bcdSAl Viro * See if the low-level filesystem might want 24555a202bcdSAl Viro * to use its own hash.. 24565a202bcdSAl Viro */ 24575a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2458da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24595a202bcdSAl Viro if (err < 0) 24605a202bcdSAl Viro return ERR_PTR(err); 24615a202bcdSAl Viro } 2462eead1911SChristoph Hellwig 2463cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2464cda309deSMiklos Szeredi if (err) 2465cda309deSMiklos Szeredi return ERR_PTR(err); 2466cda309deSMiklos Szeredi 246772bd866aSAl Viro return __lookup_hash(&this, base, 0); 2468057f6c01SJames Morris } 24694d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2470057f6c01SJames Morris 2471bbddca8eSNeilBrown /** 2472bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2473bbddca8eSNeilBrown * @name: pathname component to lookup 2474bbddca8eSNeilBrown * @base: base directory to lookup from 2475bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2476bbddca8eSNeilBrown * 2477bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2478bbddca8eSNeilBrown * not be called by generic code. 2479bbddca8eSNeilBrown * 2480bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2481bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2482bbddca8eSNeilBrown */ 2483bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2484bbddca8eSNeilBrown struct dentry *base, int len) 2485bbddca8eSNeilBrown { 2486bbddca8eSNeilBrown struct qstr this; 2487bbddca8eSNeilBrown unsigned int c; 2488bbddca8eSNeilBrown int err; 2489bbddca8eSNeilBrown 2490bbddca8eSNeilBrown this.name = name; 2491bbddca8eSNeilBrown this.len = len; 2492bbddca8eSNeilBrown this.hash = full_name_hash(name, len); 2493bbddca8eSNeilBrown if (!len) 2494bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2495bbddca8eSNeilBrown 2496bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2497bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2498bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2499bbddca8eSNeilBrown } 2500bbddca8eSNeilBrown 2501bbddca8eSNeilBrown while (len--) { 2502bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2503bbddca8eSNeilBrown if (c == '/' || c == '\0') 2504bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2505bbddca8eSNeilBrown } 2506bbddca8eSNeilBrown /* 2507bbddca8eSNeilBrown * See if the low-level filesystem might want 2508bbddca8eSNeilBrown * to use its own hash.. 2509bbddca8eSNeilBrown */ 2510bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2511bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2512bbddca8eSNeilBrown if (err < 0) 2513bbddca8eSNeilBrown return ERR_PTR(err); 2514bbddca8eSNeilBrown } 2515bbddca8eSNeilBrown 2516bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2517bbddca8eSNeilBrown if (err) 2518bbddca8eSNeilBrown return ERR_PTR(err); 2519bbddca8eSNeilBrown 25203c9fe8cdSMiklos Szeredi return lookup_hash(&this, base); 2521bbddca8eSNeilBrown } 2522bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2523bbddca8eSNeilBrown 2524eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2525eedf265aSEric W. Biederman int path_pts(struct path *path) 2526eedf265aSEric W. Biederman { 2527eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2528eedf265aSEric W. Biederman * the input path. 2529eedf265aSEric W. Biederman */ 2530eedf265aSEric W. Biederman struct dentry *child, *parent; 2531eedf265aSEric W. Biederman struct qstr this; 2532eedf265aSEric W. Biederman int ret; 2533eedf265aSEric W. Biederman 2534eedf265aSEric W. Biederman ret = path_parent_directory(path); 2535eedf265aSEric W. Biederman if (ret) 2536eedf265aSEric W. Biederman return ret; 2537eedf265aSEric W. Biederman 2538eedf265aSEric W. Biederman parent = path->dentry; 2539eedf265aSEric W. Biederman this.name = "pts"; 2540eedf265aSEric W. Biederman this.len = 3; 2541eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2542eedf265aSEric W. Biederman if (!child) 2543eedf265aSEric W. Biederman return -ENOENT; 2544eedf265aSEric W. Biederman 2545eedf265aSEric W. Biederman path->dentry = child; 2546eedf265aSEric W. Biederman dput(parent); 2547eedf265aSEric W. Biederman follow_mount(path); 2548eedf265aSEric W. Biederman return 0; 2549eedf265aSEric W. Biederman } 2550eedf265aSEric W. Biederman #endif 2551eedf265aSEric W. Biederman 25521fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25531fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25541da177e4SLinus Torvalds { 2555abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2556abc9f5beSAl Viro flags, path, NULL); 25571da177e4SLinus Torvalds } 2558b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25591fa1e7f6SAndy Whitcroft 2560873f1eedSJeff Layton /* 2561873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2562873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2563873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2564873f1eedSJeff Layton * path-walking is complete. 2565873f1eedSJeff Layton */ 2566a2ec4a2dSAl Viro static inline struct filename * 2567f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2568f5beed75SAl Viro struct path *parent, 2569f5beed75SAl Viro struct qstr *last, 2570f5beed75SAl Viro int *type, 25719e790bd6SJeff Layton unsigned int flags) 25722ad94ae6SAl Viro { 25739e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 25745c31b6ceSAl Viro return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, 25755c31b6ceSAl Viro parent, last, type); 25762ad94ae6SAl Viro } 25772ad94ae6SAl Viro 25788033426eSJeff Layton /** 2579197df04cSAl Viro * mountpoint_last - look up last component for umount 25808033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25818033426eSJeff Layton * @path: pointer to container for result 25828033426eSJeff Layton * 25838033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25848033426eSJeff Layton * need to resolve the path without doing any revalidation. 25858033426eSJeff Layton * 25868033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25878033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25888033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25898033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25908033426eSJeff Layton * bogus and it doesn't exist. 25918033426eSJeff Layton * 25928033426eSJeff Layton * Returns: 25938033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 25948033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 25958033426eSJeff Layton * put in this case. 25968033426eSJeff Layton * 25978033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 25988033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 25998033426eSJeff Layton * The nd->path reference will also be put. 26008033426eSJeff Layton * 26018033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 26028033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 26038033426eSJeff Layton * to the link, and nd->path will *not* be put. 26048033426eSJeff Layton */ 26058033426eSJeff Layton static int 2606197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 26078033426eSJeff Layton { 26088033426eSJeff Layton int error = 0; 26098033426eSJeff Layton struct dentry *dentry; 26108033426eSJeff Layton struct dentry *dir = nd->path.dentry; 26118033426eSJeff Layton 261235759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 261335759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26146e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2615deb106c6SAl Viro return -ECHILD; 26168033426eSJeff Layton } 26178033426eSJeff Layton 26188033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26198033426eSJeff Layton 26208033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26218033426eSJeff Layton error = handle_dots(nd, nd->last_type); 262235759521SAl Viro if (error) 2623deb106c6SAl Viro return error; 26248033426eSJeff Layton dentry = dget(nd->path.dentry); 2625949a852eSAl Viro } else { 26268033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 26278033426eSJeff Layton if (!dentry) { 26288033426eSJeff Layton /* 2629949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2630949a852eSAl Viro * cache, so that means that this dentry is probably 2631949a852eSAl Viro * a symlink or the path doesn't actually point 2632949a852eSAl Viro * to a mounted dentry. 26338033426eSJeff Layton */ 2634949a852eSAl Viro dentry = lookup_slow(&nd->last, dir, 2635949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2636949a852eSAl Viro if (IS_ERR(dentry)) 2637deb106c6SAl Viro return PTR_ERR(dentry); 26388033426eSJeff Layton } 2639bcceeebaSDave Jones } 2640698934dfSDavid Howells if (d_is_negative(dentry)) { 26418033426eSJeff Layton dput(dentry); 2642deb106c6SAl Viro return -ENOENT; 264335759521SAl Viro } 2644191d7f73SAl Viro if (nd->depth) 2645191d7f73SAl Viro put_link(nd); 26468033426eSJeff Layton path->dentry = dentry; 2647295dc39dSVasily Averin path->mnt = nd->path.mnt; 2648181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2649181548c0SAl Viro d_backing_inode(dentry), 0); 2650deb106c6SAl Viro if (unlikely(error)) 2651d63ff28fSAl Viro return error; 2652295dc39dSVasily Averin mntget(path->mnt); 26538033426eSJeff Layton follow_mount(path); 2654deb106c6SAl Viro return 0; 26558033426eSJeff Layton } 26568033426eSJeff Layton 26578033426eSJeff Layton /** 2658197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26592a78b857SMasanari Iida * @nd: lookup context 26608033426eSJeff Layton * @flags: lookup flags 2661c8a53ee5SAl Viro * @path: pointer to container for result 26628033426eSJeff Layton * 26638033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2664606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26658033426eSJeff Layton */ 26668033426eSJeff Layton static int 2667c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26688033426eSJeff Layton { 2669c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2670368ee9baSAl Viro int err; 2671368ee9baSAl Viro if (IS_ERR(s)) 2672368ee9baSAl Viro return PTR_ERR(s); 26733bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 26743bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 26753bdba28bSAl Viro s = trailing_symlink(nd); 26763bdba28bSAl Viro if (IS_ERR(s)) { 26773bdba28bSAl Viro err = PTR_ERR(s); 26788033426eSJeff Layton break; 26798033426eSJeff Layton } 26803bdba28bSAl Viro } 2681deb106c6SAl Viro terminate_walk(nd); 26828033426eSJeff Layton return err; 26838033426eSJeff Layton } 26848033426eSJeff Layton 26852d864651SAl Viro static int 2686668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26872d864651SAl Viro unsigned int flags) 26882d864651SAl Viro { 26899883d185SAl Viro struct nameidata nd; 2690cbaab2dbSAl Viro int error; 2691668696dcSAl Viro if (IS_ERR(name)) 2692668696dcSAl Viro return PTR_ERR(name); 26939883d185SAl Viro set_nameidata(&nd, dfd, name); 2694c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26952d864651SAl Viro if (unlikely(error == -ECHILD)) 2696c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26972d864651SAl Viro if (unlikely(error == -ESTALE)) 2698c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26992d864651SAl Viro if (likely(!error)) 2700668696dcSAl Viro audit_inode(name, path->dentry, 0); 27019883d185SAl Viro restore_nameidata(); 2702668696dcSAl Viro putname(name); 27032d864651SAl Viro return error; 27042d864651SAl Viro } 27052d864651SAl Viro 27068033426eSJeff Layton /** 2707197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27088033426eSJeff Layton * @dfd: directory file descriptor 27098033426eSJeff Layton * @name: pathname from userland 27108033426eSJeff Layton * @flags: lookup flags 27118033426eSJeff Layton * @path: pointer to container to hold result 27128033426eSJeff Layton * 27138033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27148033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27158033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27168033426eSJeff Layton * and avoid revalidating the last component. 27178033426eSJeff Layton * 27188033426eSJeff Layton * Returns 0 and populates "path" on success. 27198033426eSJeff Layton */ 27208033426eSJeff Layton int 2721197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27228033426eSJeff Layton struct path *path) 27238033426eSJeff Layton { 2724cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27258033426eSJeff Layton } 27268033426eSJeff Layton 27272d864651SAl Viro int 27282d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27292d864651SAl Viro unsigned int flags) 27302d864651SAl Viro { 2731cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27322d864651SAl Viro } 27332d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27342d864651SAl Viro 2735cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27361da177e4SLinus Torvalds { 27378e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2738da9592edSDavid Howells 27398e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27401da177e4SLinus Torvalds return 0; 27418e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27421da177e4SLinus Torvalds return 0; 274323adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27441da177e4SLinus Torvalds } 2745cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27461da177e4SLinus Torvalds 27471da177e4SLinus Torvalds /* 27481da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27491da177e4SLinus Torvalds * whether the type of victim is right. 27501da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27511da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27521da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27531da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27541da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27551da177e4SLinus Torvalds * a. be owner of dir, or 27561da177e4SLinus Torvalds * b. be owner of victim, or 27571da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27581da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27591da177e4SLinus Torvalds * links pointing to it. 27601da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27611da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27621da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 27631da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 27641da177e4SLinus Torvalds * nfs_async_unlink(). 27651da177e4SLinus Torvalds */ 2766b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27671da177e4SLinus Torvalds { 276863afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27691da177e4SLinus Torvalds int error; 27701da177e4SLinus Torvalds 2771b18825a7SDavid Howells if (d_is_negative(victim)) 27721da177e4SLinus Torvalds return -ENOENT; 2773b18825a7SDavid Howells BUG_ON(!inode); 27741da177e4SLinus Torvalds 27751da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27764fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27771da177e4SLinus Torvalds 2778f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27791da177e4SLinus Torvalds if (error) 27801da177e4SLinus Torvalds return error; 27811da177e4SLinus Torvalds if (IS_APPEND(dir)) 27821da177e4SLinus Torvalds return -EPERM; 2783b18825a7SDavid Howells 2784b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2785b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 27861da177e4SLinus Torvalds return -EPERM; 27871da177e4SLinus Torvalds if (isdir) { 278844b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27891da177e4SLinus Torvalds return -ENOTDIR; 27901da177e4SLinus Torvalds if (IS_ROOT(victim)) 27911da177e4SLinus Torvalds return -EBUSY; 279244b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27931da177e4SLinus Torvalds return -EISDIR; 27941da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27951da177e4SLinus Torvalds return -ENOENT; 27961da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27971da177e4SLinus Torvalds return -EBUSY; 27981da177e4SLinus Torvalds return 0; 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds 28011da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28021da177e4SLinus Torvalds * dir. 28031da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28041da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28051da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 28061da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 28071da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 28081da177e4SLinus Torvalds */ 2809a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28101da177e4SLinus Torvalds { 281114e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28121da177e4SLinus Torvalds if (child->d_inode) 28131da177e4SLinus Torvalds return -EEXIST; 28141da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28151da177e4SLinus Torvalds return -ENOENT; 2816f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds 28191da177e4SLinus Torvalds /* 28201da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28211da177e4SLinus Torvalds */ 28221da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28231da177e4SLinus Torvalds { 28241da177e4SLinus Torvalds struct dentry *p; 28251da177e4SLinus Torvalds 28261da177e4SLinus Torvalds if (p1 == p2) { 28275955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28281da177e4SLinus Torvalds return NULL; 28291da177e4SLinus Torvalds } 28301da177e4SLinus Torvalds 2831fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28321da177e4SLinus Torvalds 2833e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2834e2761a11SOGAWA Hirofumi if (p) { 28355955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28365955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28371da177e4SLinus Torvalds return p; 28381da177e4SLinus Torvalds } 28391da177e4SLinus Torvalds 2840e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2841e2761a11SOGAWA Hirofumi if (p) { 28425955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28435955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28441da177e4SLinus Torvalds return p; 28451da177e4SLinus Torvalds } 28461da177e4SLinus Torvalds 28475955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28485955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28491da177e4SLinus Torvalds return NULL; 28501da177e4SLinus Torvalds } 28514d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28521da177e4SLinus Torvalds 28531da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28541da177e4SLinus Torvalds { 28555955102cSAl Viro inode_unlock(p1->d_inode); 28561da177e4SLinus Torvalds if (p1 != p2) { 28575955102cSAl Viro inode_unlock(p2->d_inode); 2858fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28591da177e4SLinus Torvalds } 28601da177e4SLinus Torvalds } 28614d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28621da177e4SLinus Torvalds 28634acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2864312b63fbSAl Viro bool want_excl) 28651da177e4SLinus Torvalds { 2866a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28671da177e4SLinus Torvalds if (error) 28681da177e4SLinus Torvalds return error; 28691da177e4SLinus Torvalds 2870acfa4380SAl Viro if (!dir->i_op->create) 28711da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28721da177e4SLinus Torvalds mode &= S_IALLUGO; 28731da177e4SLinus Torvalds mode |= S_IFREG; 28741da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28751da177e4SLinus Torvalds if (error) 28761da177e4SLinus Torvalds return error; 2877312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2878a74574aaSStephen Smalley if (!error) 2879f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28801da177e4SLinus Torvalds return error; 28811da177e4SLinus Torvalds } 28824d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28831da177e4SLinus Torvalds 288473d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 28851da177e4SLinus Torvalds { 28863fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28871da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28881da177e4SLinus Torvalds int error; 28891da177e4SLinus Torvalds 28901da177e4SLinus Torvalds if (!inode) 28911da177e4SLinus Torvalds return -ENOENT; 28921da177e4SLinus Torvalds 2893c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2894c8fe8f30SChristoph Hellwig case S_IFLNK: 28951da177e4SLinus Torvalds return -ELOOP; 2896c8fe8f30SChristoph Hellwig case S_IFDIR: 2897c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28981da177e4SLinus Torvalds return -EISDIR; 2899c8fe8f30SChristoph Hellwig break; 2900c8fe8f30SChristoph Hellwig case S_IFBLK: 2901c8fe8f30SChristoph Hellwig case S_IFCHR: 29023fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 29031da177e4SLinus Torvalds return -EACCES; 2904c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2905c8fe8f30SChristoph Hellwig case S_IFIFO: 2906c8fe8f30SChristoph Hellwig case S_IFSOCK: 29071da177e4SLinus Torvalds flag &= ~O_TRUNC; 2908c8fe8f30SChristoph Hellwig break; 29094a3fd211SDave Hansen } 2910b41572e9SDave Hansen 291162fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2912b41572e9SDave Hansen if (error) 2913b41572e9SDave Hansen return error; 29146146f0d5SMimi Zohar 29151da177e4SLinus Torvalds /* 29161da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29171da177e4SLinus Torvalds */ 29181da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29198737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29207715b521SAl Viro return -EPERM; 29211da177e4SLinus Torvalds if (flag & O_TRUNC) 29227715b521SAl Viro return -EPERM; 29231da177e4SLinus Torvalds } 29241da177e4SLinus Torvalds 29251da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29262e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29277715b521SAl Viro return -EPERM; 29281da177e4SLinus Torvalds 2929f3c7691eSJ. Bruce Fields return 0; 29307715b521SAl Viro } 29317715b521SAl Viro 2932e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29337715b521SAl Viro { 2934e1181ee6SJeff Layton struct path *path = &filp->f_path; 29357715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29367715b521SAl Viro int error = get_write_access(inode); 29371da177e4SLinus Torvalds if (error) 29387715b521SAl Viro return error; 29391da177e4SLinus Torvalds /* 29401da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29411da177e4SLinus Torvalds */ 2942d7a06983SJeff Layton error = locks_verify_locked(filp); 2943be6d3e56SKentaro Takeda if (!error) 2944ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29451da177e4SLinus Torvalds if (!error) { 29467715b521SAl Viro error = do_truncate(path->dentry, 0, 2947d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2948e1181ee6SJeff Layton filp); 29491da177e4SLinus Torvalds } 29501da177e4SLinus Torvalds put_write_access(inode); 2951acd0c935SMimi Zohar return error; 29521da177e4SLinus Torvalds } 29531da177e4SLinus Torvalds 2954d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2955d57999e1SDave Hansen { 29568a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29578a5e929dSAl Viro flag--; 2958d57999e1SDave Hansen return flag; 2959d57999e1SDave Hansen } 2960d57999e1SDave Hansen 2961d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2962d18e9008SMiklos Szeredi { 2963d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2964d18e9008SMiklos Szeredi if (error) 2965d18e9008SMiklos Szeredi return error; 2966d18e9008SMiklos Szeredi 2967d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2968d18e9008SMiklos Szeredi if (error) 2969d18e9008SMiklos Szeredi return error; 2970d18e9008SMiklos Szeredi 2971d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2972d18e9008SMiklos Szeredi } 2973d18e9008SMiklos Szeredi 29741acf0af9SDavid Howells /* 29751acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29761acf0af9SDavid Howells * dentry. 29771acf0af9SDavid Howells * 29781acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29791acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29801acf0af9SDavid Howells * 29811acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29821acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29831acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29841acf0af9SDavid Howells * 29851acf0af9SDavid Howells * Returns an error code otherwise. 29861acf0af9SDavid Howells */ 29872675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 298830d90494SAl Viro struct path *path, struct file *file, 2989015c3bbcSMiklos Szeredi const struct open_flags *op, 29901643b43fSAl Viro int open_flag, umode_t mode, 299147237687SAl Viro int *opened) 2992d18e9008SMiklos Szeredi { 2993d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2994d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2995d18e9008SMiklos Szeredi int error; 2996d18e9008SMiklos Szeredi 2997384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2998d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2999d18e9008SMiklos Szeredi 3000d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3001d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3002d18e9008SMiklos Szeredi 300330d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 300430d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30050fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30060fb1ea09SAl Viro open_to_namei_flags(open_flag), 30070fb1ea09SAl Viro mode, opened); 30086fbd0714SAl Viro d_lookup_done(dentry); 3009384f26e2SAl Viro if (!error) { 3010d18e9008SMiklos Szeredi /* 3011384f26e2SAl Viro * We didn't have the inode before the open, so check open 3012384f26e2SAl Viro * permission here. 3013d18e9008SMiklos Szeredi */ 3014384f26e2SAl Viro int acc_mode = op->acc_mode; 301503da633aSAl Viro if (*opened & FILE_CREATED) { 301603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 301703da633aSAl Viro fsnotify_create(dir, dentry); 301862fb4a15SAl Viro acc_mode = 0; 301903da633aSAl Viro } 30202675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3021384f26e2SAl Viro if (WARN_ON(error > 0)) 3022384f26e2SAl Viro error = -EINVAL; 3023384f26e2SAl Viro } else if (error > 0) { 3024d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3025d18e9008SMiklos Szeredi error = -EIO; 3026384f26e2SAl Viro } else { 3027d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3028d18e9008SMiklos Szeredi dput(dentry); 3029d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 303010c64ceaSAl Viro } 3031d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3032d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3033d18e9008SMiklos Szeredi path->dentry = dentry; 3034d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30352675a4ebSAl Viro return 1; 3036d18e9008SMiklos Szeredi } 3037d18e9008SMiklos Szeredi } 3038d18e9008SMiklos Szeredi dput(dentry); 3039d18e9008SMiklos Szeredi return error; 3040d18e9008SMiklos Szeredi } 3041d18e9008SMiklos Szeredi 304231e6b01fSNick Piggin /* 30431acf0af9SDavid Howells * Look up and maybe create and open the last component. 3044d58ffd35SMiklos Szeredi * 3045d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3046d58ffd35SMiklos Szeredi * 30471acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30481acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30491acf0af9SDavid Howells * 30501acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30511acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30521acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30531acf0af9SDavid Howells * specified then a negative dentry may be returned. 30541acf0af9SDavid Howells * 30551acf0af9SDavid Howells * An error code is returned otherwise. 30561acf0af9SDavid Howells * 30571acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30581acf0af9SDavid Howells * cleared otherwise prior to returning. 3059d58ffd35SMiklos Szeredi */ 30602675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 306130d90494SAl Viro struct file *file, 3062d58ffd35SMiklos Szeredi const struct open_flags *op, 306364894cf8SAl Viro bool got_write, int *opened) 3064d58ffd35SMiklos Szeredi { 3065d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 306654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30671643b43fSAl Viro int open_flag = op->open_flag; 3068d58ffd35SMiklos Szeredi struct dentry *dentry; 30691643b43fSAl Viro int error, create_error = 0; 30701643b43fSAl Viro umode_t mode = op->mode; 30716fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3072d58ffd35SMiklos Szeredi 3073ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3074ce8644fcSAl Viro return -ENOENT; 3075d58ffd35SMiklos Szeredi 307647237687SAl Viro *opened &= ~FILE_CREATED; 30776fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30786fbd0714SAl Viro for (;;) { 30796fbd0714SAl Viro if (!dentry) { 30806fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3081d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30822675a4ebSAl Viro return PTR_ERR(dentry); 30836fbd0714SAl Viro } 30846fbd0714SAl Viro if (d_in_lookup(dentry)) 30856fbd0714SAl Viro break; 3086d58ffd35SMiklos Szeredi 30876fbd0714SAl Viro if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) 30886fbd0714SAl Viro break; 30896fbd0714SAl Viro 30906fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30916fbd0714SAl Viro if (likely(error > 0)) 30926fbd0714SAl Viro break; 30936fbd0714SAl Viro if (error) 30946fbd0714SAl Viro goto out_dput; 30956fbd0714SAl Viro d_invalidate(dentry); 30966fbd0714SAl Viro dput(dentry); 30976fbd0714SAl Viro dentry = NULL; 30986fbd0714SAl Viro } 30996fbd0714SAl Viro if (dentry->d_inode) { 3100d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3101d18e9008SMiklos Szeredi goto out_no_open; 31026c51e513SAl Viro } 3103d18e9008SMiklos Szeredi 31041643b43fSAl Viro /* 31051643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31061643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31071643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31081643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31091643b43fSAl Viro * 31101643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31111643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31121643b43fSAl Viro */ 31131643b43fSAl Viro if (open_flag & O_CREAT) { 31141643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31151643b43fSAl Viro mode &= ~current_umask(); 31161643b43fSAl Viro if (unlikely(!got_write)) { 31171643b43fSAl Viro create_error = -EROFS; 31181643b43fSAl Viro open_flag &= ~O_CREAT; 31191643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31201643b43fSAl Viro goto no_open; 31211643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31221643b43fSAl Viro } else { 31231643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31241643b43fSAl Viro if (create_error) { 31251643b43fSAl Viro open_flag &= ~O_CREAT; 31261643b43fSAl Viro if (open_flag & O_EXCL) 31271643b43fSAl Viro goto no_open; 31281643b43fSAl Viro } 31291643b43fSAl Viro } 31301643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31311643b43fSAl Viro unlikely(!got_write)) { 31321643b43fSAl Viro /* 31331643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31341643b43fSAl Viro * back to lookup + open 31351643b43fSAl Viro */ 31361643b43fSAl Viro goto no_open; 3137d18e9008SMiklos Szeredi } 3138d18e9008SMiklos Szeredi 31391643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31401643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31411643b43fSAl Viro mode, opened); 31421643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31431643b43fSAl Viro error = create_error; 31441643b43fSAl Viro return error; 31451643b43fSAl Viro } 314654ef4872SMiklos Szeredi 31471643b43fSAl Viro no_open: 31486fbd0714SAl Viro if (d_in_lookup(dentry)) { 314912fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 315012fa5e24SAl Viro nd->flags); 31516fbd0714SAl Viro d_lookup_done(dentry); 315212fa5e24SAl Viro if (unlikely(res)) { 315312fa5e24SAl Viro if (IS_ERR(res)) { 315412fa5e24SAl Viro error = PTR_ERR(res); 315512fa5e24SAl Viro goto out_dput; 315612fa5e24SAl Viro } 315712fa5e24SAl Viro dput(dentry); 315812fa5e24SAl Viro dentry = res; 315912fa5e24SAl Viro } 316054ef4872SMiklos Szeredi } 316154ef4872SMiklos Szeredi 3162d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31631643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 316447237687SAl Viro *opened |= FILE_CREATED; 3165ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3166ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3167ce8644fcSAl Viro error = -EACCES; 3168d58ffd35SMiklos Szeredi goto out_dput; 316977d660a8SMiklos Szeredi } 3170ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31711643b43fSAl Viro open_flag & O_EXCL); 3172d58ffd35SMiklos Szeredi if (error) 3173d58ffd35SMiklos Szeredi goto out_dput; 3174ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3175d58ffd35SMiklos Szeredi } 31761643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31771643b43fSAl Viro error = create_error; 3178d58ffd35SMiklos Szeredi goto out_dput; 3179d58ffd35SMiklos Szeredi } 3180d18e9008SMiklos Szeredi out_no_open: 3181d58ffd35SMiklos Szeredi path->dentry = dentry; 3182d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31832675a4ebSAl Viro return 1; 3184d58ffd35SMiklos Szeredi 3185d58ffd35SMiklos Szeredi out_dput: 3186d58ffd35SMiklos Szeredi dput(dentry); 31872675a4ebSAl Viro return error; 3188d58ffd35SMiklos Szeredi } 3189d58ffd35SMiklos Szeredi 3190d58ffd35SMiklos Szeredi /* 3191fe2d35ffSAl Viro * Handle the last step of open() 319231e6b01fSNick Piggin */ 3193896475d5SAl Viro static int do_last(struct nameidata *nd, 319430d90494SAl Viro struct file *file, const struct open_flags *op, 319576ae2a5aSAl Viro int *opened) 3196fb1cc555SAl Viro { 3197a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3198ca344a89SAl Viro int open_flag = op->open_flag; 319977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 320064894cf8SAl Viro bool got_write = false; 3201bcda7652SAl Viro int acc_mode = op->acc_mode; 3202254cf582SAl Viro unsigned seq; 3203a1eb3315SMiklos Szeredi struct inode *inode; 320416b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 3205896475d5SAl Viro struct path path; 320616b1c1cdSMiklos Szeredi bool retried = false; 320716c2cd71SAl Viro int error; 3208fb1cc555SAl Viro 3209c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3210c3e380b0SAl Viro nd->flags |= op->intent; 3211c3e380b0SAl Viro 3212bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3213fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3214deb106c6SAl Viro if (unlikely(error)) 32152675a4ebSAl Viro return error; 3216e83db167SMiklos Szeredi goto finish_open; 32171f36f774SAl Viro } 3218a2c36b45SAl Viro 3219ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3220fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3221fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3222fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3223254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3224e9742b53SAl Viro if (likely(error > 0)) 322571574865SMiklos Szeredi goto finish_lookup; 322671574865SMiklos Szeredi 3227ce57dfc1SAl Viro if (error < 0) 3228deb106c6SAl Viro return error; 3229a1eb3315SMiklos Szeredi 323037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32316583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3232b6183df7SMiklos Szeredi } else { 3233fe2d35ffSAl Viro /* create side of things */ 3234a3fbbde7SAl Viro /* 3235b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3236b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3237b6183df7SMiklos Szeredi * about to look up 3238a3fbbde7SAl Viro */ 32399f1fafeeSAl Viro error = complete_walk(nd); 3240e8bb73dfSAl Viro if (error) 32412675a4ebSAl Viro return error; 3242fe2d35ffSAl Viro 324376ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32441f36f774SAl Viro /* trailing slashes? */ 3245deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3246deb106c6SAl Viro return -EISDIR; 3247b6183df7SMiklos Szeredi } 32481f36f774SAl Viro 324916b1c1cdSMiklos Szeredi retry_lookup: 32509cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 325164894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 325264894cf8SAl Viro if (!error) 325364894cf8SAl Viro got_write = true; 325464894cf8SAl Viro /* 325564894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 325664894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 325764894cf8SAl Viro * dropping this one anyway. 325864894cf8SAl Viro */ 325964894cf8SAl Viro } 32609cf843e3SAl Viro if (open_flag & O_CREAT) 32615955102cSAl Viro inode_lock(dir->d_inode); 32629cf843e3SAl Viro else 32639cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3264896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32659cf843e3SAl Viro if (open_flag & O_CREAT) 32665955102cSAl Viro inode_unlock(dir->d_inode); 32679cf843e3SAl Viro else 32689cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3269fb1cc555SAl Viro 32702675a4ebSAl Viro if (error <= 0) { 32712675a4ebSAl Viro if (error) 3272d58ffd35SMiklos Szeredi goto out; 32736c0d46c4SAl Viro 327447237687SAl Viro if ((*opened & FILE_CREATED) || 3275496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 327677d660a8SMiklos Szeredi will_truncate = false; 3277d18e9008SMiklos Szeredi 327876ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3279d18e9008SMiklos Szeredi goto opened; 3280d18e9008SMiklos Szeredi } 3281d18e9008SMiklos Szeredi 328247237687SAl Viro if (*opened & FILE_CREATED) { 32839b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3284ca344a89SAl Viro open_flag &= ~O_TRUNC; 328577d660a8SMiklos Szeredi will_truncate = false; 328662fb4a15SAl Viro acc_mode = 0; 3287896475d5SAl Viro path_to_nameidata(&path, nd); 3288e83db167SMiklos Szeredi goto finish_open_created; 3289fb1cc555SAl Viro } 3290fb1cc555SAl Viro 3291fb1cc555SAl Viro /* 3292d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3293d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3294d18e9008SMiklos Szeredi * necessary...) 3295d18e9008SMiklos Szeredi */ 329664894cf8SAl Viro if (got_write) { 3297d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 329864894cf8SAl Viro got_write = false; 3299d18e9008SMiklos Szeredi } 3300d18e9008SMiklos Szeredi 33016583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33026583fe22SAl Viro path_to_nameidata(&path, nd); 33036583fe22SAl Viro return -ENOENT; 33046583fe22SAl Viro } 33056583fe22SAl Viro 33066583fe22SAl Viro /* 33076583fe22SAl Viro * create/update audit record if it already exists. 33086583fe22SAl Viro */ 33096583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33106583fe22SAl Viro 3311deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3312deb106c6SAl Viro path_to_nameidata(&path, nd); 3313deb106c6SAl Viro return -EEXIST; 3314deb106c6SAl Viro } 3315fb1cc555SAl Viro 3316756daf26SNeilBrown error = follow_managed(&path, nd); 3317deb106c6SAl Viro if (unlikely(error < 0)) 3318deb106c6SAl Viro return error; 3319a3fbbde7SAl Viro 3320254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3321d4565649SAl Viro inode = d_backing_inode(path.dentry); 3322766c4cbfSAl Viro finish_lookup: 3323191d7f73SAl Viro if (nd->depth) 3324191d7f73SAl Viro put_link(nd); 3325181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3326181548c0SAl Viro inode, seq); 3327deb106c6SAl Viro if (unlikely(error)) 3328d63ff28fSAl Viro return error; 3329fb1cc555SAl Viro 3330896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3331896475d5SAl Viro path_to_nameidata(&path, nd); 333216b1c1cdSMiklos Szeredi } else { 333316b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3334896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3335896475d5SAl Viro nd->path.dentry = path.dentry; 333616b1c1cdSMiklos Szeredi 333716b1c1cdSMiklos Szeredi } 3338decf3400SMiklos Szeredi nd->inode = inode; 3339254cf582SAl Viro nd->seq = seq; 3340a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3341bc77daa7SAl Viro finish_open: 3342a3fbbde7SAl Viro error = complete_walk(nd); 334316b1c1cdSMiklos Szeredi if (error) { 334416b1c1cdSMiklos Szeredi path_put(&save_parent); 33452675a4ebSAl Viro return error; 334616b1c1cdSMiklos Szeredi } 334776ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3348fb1cc555SAl Viro error = -EISDIR; 334944b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33502675a4ebSAl Viro goto out; 3351af2f5542SMiklos Szeredi error = -ENOTDIR; 335244b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33532675a4ebSAl Viro goto out; 33544bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 335577d660a8SMiklos Szeredi will_truncate = false; 33566c0d46c4SAl Viro 33570f9d1a10SAl Viro if (will_truncate) { 33580f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33590f9d1a10SAl Viro if (error) 33602675a4ebSAl Viro goto out; 336164894cf8SAl Viro got_write = true; 33620f9d1a10SAl Viro } 3363e83db167SMiklos Szeredi finish_open_created: 3364bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3365ca344a89SAl Viro if (error) 33662675a4ebSAl Viro goto out; 33674aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33684aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 33694aa7c634SMiklos Szeredi if (!error) { 33704aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 33714aa7c634SMiklos Szeredi } else { 337230d90494SAl Viro if (error == -EOPENSTALE) 3373f60dc3dbSMiklos Szeredi goto stale_open; 3374015c3bbcSMiklos Szeredi goto out; 3375f60dc3dbSMiklos Szeredi } 3376a8277b9bSMiklos Szeredi opened: 33772675a4ebSAl Viro error = open_check_o_direct(file); 3378fe9ec829SAl Viro if (!error) 33793034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3380fe9ec829SAl Viro if (!error && will_truncate) 33812675a4ebSAl Viro error = handle_truncate(file); 3382ca344a89SAl Viro out: 3383fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3384fe9ec829SAl Viro fput(file); 3385c80567c8SAl Viro if (unlikely(error > 0)) { 3386c80567c8SAl Viro WARN_ON(1); 3387c80567c8SAl Viro error = -EINVAL; 3388c80567c8SAl Viro } 338964894cf8SAl Viro if (got_write) 33900f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 339116b1c1cdSMiklos Szeredi path_put(&save_parent); 33922675a4ebSAl Viro return error; 3393fb1cc555SAl Viro 3394f60dc3dbSMiklos Szeredi stale_open: 3395f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3396f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3397f60dc3dbSMiklos Szeredi goto out; 3398f60dc3dbSMiklos Szeredi 3399f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3400f60dc3dbSMiklos Szeredi path_put(&nd->path); 3401f60dc3dbSMiklos Szeredi nd->path = save_parent; 3402f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3403f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3404f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 340564894cf8SAl Viro if (got_write) { 3406f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 340764894cf8SAl Viro got_write = false; 3408f60dc3dbSMiklos Szeredi } 3409f60dc3dbSMiklos Szeredi retried = true; 3410f60dc3dbSMiklos Szeredi goto retry_lookup; 3411fb1cc555SAl Viro } 3412fb1cc555SAl Viro 3413c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 341460545d0dSAl Viro const struct open_flags *op, 341560545d0dSAl Viro struct file *file, int *opened) 341660545d0dSAl Viro { 341760545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 3418625b6d10SAl Viro struct dentry *child; 341960545d0dSAl Viro struct inode *dir; 3420625b6d10SAl Viro struct path path; 3421c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 342260545d0dSAl Viro if (unlikely(error)) 342360545d0dSAl Viro return error; 3424625b6d10SAl Viro error = mnt_want_write(path.mnt); 342560545d0dSAl Viro if (unlikely(error)) 342660545d0dSAl Viro goto out; 3427625b6d10SAl Viro dir = path.dentry->d_inode; 342860545d0dSAl Viro /* we want directory to be writable */ 3429625b6d10SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 343060545d0dSAl Viro if (error) 343160545d0dSAl Viro goto out2; 343260545d0dSAl Viro if (!dir->i_op->tmpfile) { 343360545d0dSAl Viro error = -EOPNOTSUPP; 343460545d0dSAl Viro goto out2; 343560545d0dSAl Viro } 3436625b6d10SAl Viro child = d_alloc(path.dentry, &name); 343760545d0dSAl Viro if (unlikely(!child)) { 343860545d0dSAl Viro error = -ENOMEM; 343960545d0dSAl Viro goto out2; 344060545d0dSAl Viro } 3441625b6d10SAl Viro dput(path.dentry); 3442625b6d10SAl Viro path.dentry = child; 3443625b6d10SAl Viro error = dir->i_op->tmpfile(dir, child, op->mode); 344460545d0dSAl Viro if (error) 344560545d0dSAl Viro goto out2; 3446c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 344769a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 344862fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 344960545d0dSAl Viro if (error) 345060545d0dSAl Viro goto out2; 3451625b6d10SAl Viro file->f_path.mnt = path.mnt; 3452625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 345360545d0dSAl Viro if (error) 345460545d0dSAl Viro goto out2; 345560545d0dSAl Viro error = open_check_o_direct(file); 3456f4e0c30cSAl Viro if (error) { 345760545d0dSAl Viro fput(file); 3458f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3459f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3460f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3461f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3462f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3463f4e0c30cSAl Viro } 346460545d0dSAl Viro out2: 3465625b6d10SAl Viro mnt_drop_write(path.mnt); 346660545d0dSAl Viro out: 3467625b6d10SAl Viro path_put(&path); 346860545d0dSAl Viro return error; 346960545d0dSAl Viro } 347060545d0dSAl Viro 34716ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34726ac08709SAl Viro { 34736ac08709SAl Viro struct path path; 34746ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34756ac08709SAl Viro if (!error) { 34766ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34776ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34786ac08709SAl Viro path_put(&path); 34796ac08709SAl Viro } 34806ac08709SAl Viro return error; 34816ac08709SAl Viro } 34826ac08709SAl Viro 3483c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3484c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34851da177e4SLinus Torvalds { 3486368ee9baSAl Viro const char *s; 348730d90494SAl Viro struct file *file; 348847237687SAl Viro int opened = 0; 348913aab428SAl Viro int error; 349031e6b01fSNick Piggin 349130d90494SAl Viro file = get_empty_filp(); 34921afc99beSAl Viro if (IS_ERR(file)) 34931afc99beSAl Viro return file; 349431e6b01fSNick Piggin 349530d90494SAl Viro file->f_flags = op->open_flag; 349631e6b01fSNick Piggin 3497bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3498c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3499f15133dfSAl Viro goto out2; 350060545d0dSAl Viro } 350160545d0dSAl Viro 35026ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 35036ac08709SAl Viro error = do_o_path(nd, flags, file); 35046ac08709SAl Viro if (!error) 35056ac08709SAl Viro opened |= FILE_OPENED; 35066ac08709SAl Viro goto out2; 35076ac08709SAl Viro } 35086ac08709SAl Viro 3509c8a53ee5SAl Viro s = path_init(nd, flags); 3510368ee9baSAl Viro if (IS_ERR(s)) { 3511368ee9baSAl Viro put_filp(file); 3512368ee9baSAl Viro return ERR_CAST(s); 3513368ee9baSAl Viro } 35143bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 351576ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 351673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35173bdba28bSAl Viro s = trailing_symlink(nd); 35183bdba28bSAl Viro if (IS_ERR(s)) { 35193bdba28bSAl Viro error = PTR_ERR(s); 35202675a4ebSAl Viro break; 3521806b681cSAl Viro } 35223bdba28bSAl Viro } 3523deb106c6SAl Viro terminate_walk(nd); 3524f15133dfSAl Viro out2: 35252675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35262675a4ebSAl Viro BUG_ON(!error); 352730d90494SAl Viro put_filp(file); 3528015c3bbcSMiklos Szeredi } 35292675a4ebSAl Viro if (unlikely(error)) { 35302675a4ebSAl Viro if (error == -EOPENSTALE) { 35312675a4ebSAl Viro if (flags & LOOKUP_RCU) 35322675a4ebSAl Viro error = -ECHILD; 35332675a4ebSAl Viro else 35342675a4ebSAl Viro error = -ESTALE; 35352675a4ebSAl Viro } 35362675a4ebSAl Viro file = ERR_PTR(error); 35372675a4ebSAl Viro } 35382675a4ebSAl Viro return file; 3539de459215SKirill Korotaev } 35401da177e4SLinus Torvalds 3541669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3542f9652e10SAl Viro const struct open_flags *op) 354313aab428SAl Viro { 35449883d185SAl Viro struct nameidata nd; 3545f9652e10SAl Viro int flags = op->lookup_flags; 354613aab428SAl Viro struct file *filp; 354713aab428SAl Viro 35489883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3549c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 355013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3551c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 355213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3553c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35549883d185SAl Viro restore_nameidata(); 355513aab428SAl Viro return filp; 355613aab428SAl Viro } 355713aab428SAl Viro 355873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3559f9652e10SAl Viro const char *name, const struct open_flags *op) 356073d049a4SAl Viro { 35619883d185SAl Viro struct nameidata nd; 356273d049a4SAl Viro struct file *file; 356351689104SPaul Moore struct filename *filename; 3564f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 356573d049a4SAl Viro 356673d049a4SAl Viro nd.root.mnt = mnt; 356773d049a4SAl Viro nd.root.dentry = dentry; 356873d049a4SAl Viro 3569b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 357073d049a4SAl Viro return ERR_PTR(-ELOOP); 357173d049a4SAl Viro 357251689104SPaul Moore filename = getname_kernel(name); 3573a1c83681SViresh Kumar if (IS_ERR(filename)) 357451689104SPaul Moore return ERR_CAST(filename); 357551689104SPaul Moore 35769883d185SAl Viro set_nameidata(&nd, -1, filename); 3577c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 357873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3579c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 358073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3581c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35829883d185SAl Viro restore_nameidata(); 358351689104SPaul Moore putname(filename); 358473d049a4SAl Viro return file; 358573d049a4SAl Viro } 358673d049a4SAl Viro 3587fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35881ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35891da177e4SLinus Torvalds { 3590c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3591391172c4SAl Viro struct qstr last; 3592391172c4SAl Viro int type; 3593c30dabfeSJan Kara int err2; 35941ac12b4bSJeff Layton int error; 35951ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35961ac12b4bSJeff Layton 35971ac12b4bSJeff Layton /* 35981ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35991ac12b4bSJeff Layton * other flags passed in are ignored! 36001ac12b4bSJeff Layton */ 36011ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 36021ac12b4bSJeff Layton 36035c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36045c31b6ceSAl Viro if (IS_ERR(name)) 36055c31b6ceSAl Viro return ERR_CAST(name); 36061da177e4SLinus Torvalds 3607c663e5d8SChristoph Hellwig /* 3608c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3609c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3610c663e5d8SChristoph Hellwig */ 36115c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3612ed75e95dSAl Viro goto out; 3613c663e5d8SChristoph Hellwig 3614c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3615391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3616c663e5d8SChristoph Hellwig /* 3617c663e5d8SChristoph Hellwig * Do the final lookup. 3618c663e5d8SChristoph Hellwig */ 3619391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36205955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3621391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36221da177e4SLinus Torvalds if (IS_ERR(dentry)) 3623a8104a9fSAl Viro goto unlock; 3624c663e5d8SChristoph Hellwig 3625a8104a9fSAl Viro error = -EEXIST; 3626b18825a7SDavid Howells if (d_is_positive(dentry)) 3627a8104a9fSAl Viro goto fail; 3628b18825a7SDavid Howells 3629c663e5d8SChristoph Hellwig /* 3630c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3631c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3632c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3633c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3634c663e5d8SChristoph Hellwig */ 3635391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3636a8104a9fSAl Viro error = -ENOENT; 3637ed75e95dSAl Viro goto fail; 3638e9baf6e5SAl Viro } 3639c30dabfeSJan Kara if (unlikely(err2)) { 3640c30dabfeSJan Kara error = err2; 3641a8104a9fSAl Viro goto fail; 3642c30dabfeSJan Kara } 3643181c37b6SAl Viro putname(name); 3644e9baf6e5SAl Viro return dentry; 36451da177e4SLinus Torvalds fail: 3646a8104a9fSAl Viro dput(dentry); 3647a8104a9fSAl Viro dentry = ERR_PTR(error); 3648a8104a9fSAl Viro unlock: 36495955102cSAl Viro inode_unlock(path->dentry->d_inode); 3650c30dabfeSJan Kara if (!err2) 3651391172c4SAl Viro mnt_drop_write(path->mnt); 3652ed75e95dSAl Viro out: 3653391172c4SAl Viro path_put(path); 3654181c37b6SAl Viro putname(name); 3655ed75e95dSAl Viro return dentry; 3656dae6ad8fSAl Viro } 3657fa14a0b8SAl Viro 3658fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3659fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3660fa14a0b8SAl Viro { 3661181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3662181c37b6SAl Viro path, lookup_flags); 3663fa14a0b8SAl Viro } 3664dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3665dae6ad8fSAl Viro 3666921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3667921a1650SAl Viro { 3668921a1650SAl Viro dput(dentry); 36695955102cSAl Viro inode_unlock(path->dentry->d_inode); 3670a8104a9fSAl Viro mnt_drop_write(path->mnt); 3671921a1650SAl Viro path_put(path); 3672921a1650SAl Viro } 3673921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3674921a1650SAl Viro 3675520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36761ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3677dae6ad8fSAl Viro { 3678181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3679dae6ad8fSAl Viro } 3680dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3681dae6ad8fSAl Viro 36821a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36831da177e4SLinus Torvalds { 3684a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36851da177e4SLinus Torvalds 36861da177e4SLinus Torvalds if (error) 36871da177e4SLinus Torvalds return error; 36881da177e4SLinus Torvalds 3689975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36901da177e4SLinus Torvalds return -EPERM; 36911da177e4SLinus Torvalds 3692acfa4380SAl Viro if (!dir->i_op->mknod) 36931da177e4SLinus Torvalds return -EPERM; 36941da177e4SLinus Torvalds 369508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 369608ce5f16SSerge E. Hallyn if (error) 369708ce5f16SSerge E. Hallyn return error; 369808ce5f16SSerge E. Hallyn 36991da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 37001da177e4SLinus Torvalds if (error) 37011da177e4SLinus Torvalds return error; 37021da177e4SLinus Torvalds 37031da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3704a74574aaSStephen Smalley if (!error) 3705f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37061da177e4SLinus Torvalds return error; 37071da177e4SLinus Torvalds } 37084d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37091da177e4SLinus Torvalds 3710f69aac00SAl Viro static int may_mknod(umode_t mode) 3711463c3197SDave Hansen { 3712463c3197SDave Hansen switch (mode & S_IFMT) { 3713463c3197SDave Hansen case S_IFREG: 3714463c3197SDave Hansen case S_IFCHR: 3715463c3197SDave Hansen case S_IFBLK: 3716463c3197SDave Hansen case S_IFIFO: 3717463c3197SDave Hansen case S_IFSOCK: 3718463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3719463c3197SDave Hansen return 0; 3720463c3197SDave Hansen case S_IFDIR: 3721463c3197SDave Hansen return -EPERM; 3722463c3197SDave Hansen default: 3723463c3197SDave Hansen return -EINVAL; 3724463c3197SDave Hansen } 3725463c3197SDave Hansen } 3726463c3197SDave Hansen 37278208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37282e4d0924SHeiko Carstens unsigned, dev) 37291da177e4SLinus Torvalds { 37301da177e4SLinus Torvalds struct dentry *dentry; 3731dae6ad8fSAl Viro struct path path; 3732dae6ad8fSAl Viro int error; 3733972567f1SJeff Layton unsigned int lookup_flags = 0; 37341da177e4SLinus Torvalds 37358e4bfca1SAl Viro error = may_mknod(mode); 37368e4bfca1SAl Viro if (error) 37378e4bfca1SAl Viro return error; 3738972567f1SJeff Layton retry: 3739972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3740dae6ad8fSAl Viro if (IS_ERR(dentry)) 3741dae6ad8fSAl Viro return PTR_ERR(dentry); 37422ad94ae6SAl Viro 3743dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3744ce3b0f8dSAl Viro mode &= ~current_umask(); 3745dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3746be6d3e56SKentaro Takeda if (error) 3747a8104a9fSAl Viro goto out; 37481da177e4SLinus Torvalds switch (mode & S_IFMT) { 37491da177e4SLinus Torvalds case 0: case S_IFREG: 3750312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 375105d1a717SMimi Zohar if (!error) 375205d1a717SMimi Zohar ima_post_path_mknod(dentry); 37531da177e4SLinus Torvalds break; 37541da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3755dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37561da177e4SLinus Torvalds new_decode_dev(dev)); 37571da177e4SLinus Torvalds break; 37581da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3759dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37601da177e4SLinus Torvalds break; 37611da177e4SLinus Torvalds } 3762a8104a9fSAl Viro out: 3763921a1650SAl Viro done_path_create(&path, dentry); 3764972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3765972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3766972567f1SJeff Layton goto retry; 3767972567f1SJeff Layton } 37681da177e4SLinus Torvalds return error; 37691da177e4SLinus Torvalds } 37701da177e4SLinus Torvalds 37718208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37725590ff0dSUlrich Drepper { 37735590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37745590ff0dSUlrich Drepper } 37755590ff0dSUlrich Drepper 377618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37771da177e4SLinus Torvalds { 3778a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37798de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37801da177e4SLinus Torvalds 37811da177e4SLinus Torvalds if (error) 37821da177e4SLinus Torvalds return error; 37831da177e4SLinus Torvalds 3784acfa4380SAl Viro if (!dir->i_op->mkdir) 37851da177e4SLinus Torvalds return -EPERM; 37861da177e4SLinus Torvalds 37871da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37881da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37891da177e4SLinus Torvalds if (error) 37901da177e4SLinus Torvalds return error; 37911da177e4SLinus Torvalds 37928de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37938de52778SAl Viro return -EMLINK; 37948de52778SAl Viro 37951da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3796a74574aaSStephen Smalley if (!error) 3797f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds } 38004d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 38011da177e4SLinus Torvalds 3802a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38031da177e4SLinus Torvalds { 38046902d925SDave Hansen struct dentry *dentry; 3805dae6ad8fSAl Viro struct path path; 3806dae6ad8fSAl Viro int error; 3807b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38081da177e4SLinus Torvalds 3809b76d8b82SJeff Layton retry: 3810b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38116902d925SDave Hansen if (IS_ERR(dentry)) 3812dae6ad8fSAl Viro return PTR_ERR(dentry); 38136902d925SDave Hansen 3814dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3815ce3b0f8dSAl Viro mode &= ~current_umask(); 3816dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3817a8104a9fSAl Viro if (!error) 3818dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3819921a1650SAl Viro done_path_create(&path, dentry); 3820b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3821b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3822b76d8b82SJeff Layton goto retry; 3823b76d8b82SJeff Layton } 38241da177e4SLinus Torvalds return error; 38251da177e4SLinus Torvalds } 38261da177e4SLinus Torvalds 3827a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38285590ff0dSUlrich Drepper { 38295590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38305590ff0dSUlrich Drepper } 38315590ff0dSUlrich Drepper 38321da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38331da177e4SLinus Torvalds { 38341da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38351da177e4SLinus Torvalds 38361da177e4SLinus Torvalds if (error) 38371da177e4SLinus Torvalds return error; 38381da177e4SLinus Torvalds 3839acfa4380SAl Viro if (!dir->i_op->rmdir) 38401da177e4SLinus Torvalds return -EPERM; 38411da177e4SLinus Torvalds 38421d2ef590SAl Viro dget(dentry); 38435955102cSAl Viro inode_lock(dentry->d_inode); 3844912dbc15SSage Weil 38451da177e4SLinus Torvalds error = -EBUSY; 38467af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3847912dbc15SSage Weil goto out; 3848912dbc15SSage Weil 38491da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3850912dbc15SSage Weil if (error) 3851912dbc15SSage Weil goto out; 3852912dbc15SSage Weil 38533cebde24SSage Weil shrink_dcache_parent(dentry); 38541da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3855912dbc15SSage Weil if (error) 3856912dbc15SSage Weil goto out; 3857912dbc15SSage Weil 38581da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3859d83c49f3SAl Viro dont_mount(dentry); 38608ed936b5SEric W. Biederman detach_mounts(dentry); 38611da177e4SLinus Torvalds 3862912dbc15SSage Weil out: 38635955102cSAl Viro inode_unlock(dentry->d_inode); 38641d2ef590SAl Viro dput(dentry); 3865912dbc15SSage Weil if (!error) 3866912dbc15SSage Weil d_delete(dentry); 38671da177e4SLinus Torvalds return error; 38681da177e4SLinus Torvalds } 38694d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38701da177e4SLinus Torvalds 38715590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38721da177e4SLinus Torvalds { 38731da177e4SLinus Torvalds int error = 0; 387491a27b2aSJeff Layton struct filename *name; 38751da177e4SLinus Torvalds struct dentry *dentry; 3876f5beed75SAl Viro struct path path; 3877f5beed75SAl Viro struct qstr last; 3878f5beed75SAl Viro int type; 3879c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3880c6ee9206SJeff Layton retry: 3881f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3882f5beed75SAl Viro &path, &last, &type, lookup_flags); 388391a27b2aSJeff Layton if (IS_ERR(name)) 388491a27b2aSJeff Layton return PTR_ERR(name); 38851da177e4SLinus Torvalds 3886f5beed75SAl Viro switch (type) { 38871da177e4SLinus Torvalds case LAST_DOTDOT: 38881da177e4SLinus Torvalds error = -ENOTEMPTY; 38891da177e4SLinus Torvalds goto exit1; 38901da177e4SLinus Torvalds case LAST_DOT: 38911da177e4SLinus Torvalds error = -EINVAL; 38921da177e4SLinus Torvalds goto exit1; 38931da177e4SLinus Torvalds case LAST_ROOT: 38941da177e4SLinus Torvalds error = -EBUSY; 38951da177e4SLinus Torvalds goto exit1; 38961da177e4SLinus Torvalds } 38970612d9fbSOGAWA Hirofumi 3898f5beed75SAl Viro error = mnt_want_write(path.mnt); 3899c30dabfeSJan Kara if (error) 3900c30dabfeSJan Kara goto exit1; 39010612d9fbSOGAWA Hirofumi 39025955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3903f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39041da177e4SLinus Torvalds error = PTR_ERR(dentry); 39056902d925SDave Hansen if (IS_ERR(dentry)) 39066902d925SDave Hansen goto exit2; 3907e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3908e6bc45d6STheodore Ts'o error = -ENOENT; 3909e6bc45d6STheodore Ts'o goto exit3; 3910e6bc45d6STheodore Ts'o } 3911f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3912be6d3e56SKentaro Takeda if (error) 3913c30dabfeSJan Kara goto exit3; 3914f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39150622753bSDave Hansen exit3: 39161da177e4SLinus Torvalds dput(dentry); 39176902d925SDave Hansen exit2: 39185955102cSAl Viro inode_unlock(path.dentry->d_inode); 3919f5beed75SAl Viro mnt_drop_write(path.mnt); 39201da177e4SLinus Torvalds exit1: 3921f5beed75SAl Viro path_put(&path); 39221da177e4SLinus Torvalds putname(name); 3923c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3924c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3925c6ee9206SJeff Layton goto retry; 3926c6ee9206SJeff Layton } 39271da177e4SLinus Torvalds return error; 39281da177e4SLinus Torvalds } 39291da177e4SLinus Torvalds 39303cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39315590ff0dSUlrich Drepper { 39325590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39335590ff0dSUlrich Drepper } 39345590ff0dSUlrich Drepper 3935b21996e3SJ. Bruce Fields /** 3936b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3937b21996e3SJ. Bruce Fields * @dir: parent directory 3938b21996e3SJ. Bruce Fields * @dentry: victim 3939b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3940b21996e3SJ. Bruce Fields * 3941b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3942b21996e3SJ. Bruce Fields * 3943b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3944b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3945b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3946b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3947b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3948b21996e3SJ. Bruce Fields * 3949b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3950b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3951b21996e3SJ. Bruce Fields * to be NFS exported. 3952b21996e3SJ. Bruce Fields */ 3953b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39541da177e4SLinus Torvalds { 39559accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39561da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39571da177e4SLinus Torvalds 39581da177e4SLinus Torvalds if (error) 39591da177e4SLinus Torvalds return error; 39601da177e4SLinus Torvalds 3961acfa4380SAl Viro if (!dir->i_op->unlink) 39621da177e4SLinus Torvalds return -EPERM; 39631da177e4SLinus Torvalds 39645955102cSAl Viro inode_lock(target); 39658ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39661da177e4SLinus Torvalds error = -EBUSY; 39671da177e4SLinus Torvalds else { 39681da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3969bec1052eSAl Viro if (!error) { 39705a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39715a14696cSJ. Bruce Fields if (error) 3972b21996e3SJ. Bruce Fields goto out; 39731da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39748ed936b5SEric W. Biederman if (!error) { 3975d83c49f3SAl Viro dont_mount(dentry); 39768ed936b5SEric W. Biederman detach_mounts(dentry); 39778ed936b5SEric W. Biederman } 3978bec1052eSAl Viro } 39791da177e4SLinus Torvalds } 3980b21996e3SJ. Bruce Fields out: 39815955102cSAl Viro inode_unlock(target); 39821da177e4SLinus Torvalds 39831da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39841da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39859accbb97SJ. Bruce Fields fsnotify_link_count(target); 39861da177e4SLinus Torvalds d_delete(dentry); 39871da177e4SLinus Torvalds } 39880eeca283SRobert Love 39891da177e4SLinus Torvalds return error; 39901da177e4SLinus Torvalds } 39914d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39921da177e4SLinus Torvalds 39931da177e4SLinus Torvalds /* 39941da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39951b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39961da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39971da177e4SLinus Torvalds * while waiting on the I/O. 39981da177e4SLinus Torvalds */ 39995590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 40001da177e4SLinus Torvalds { 40012ad94ae6SAl Viro int error; 400291a27b2aSJeff Layton struct filename *name; 40031da177e4SLinus Torvalds struct dentry *dentry; 4004f5beed75SAl Viro struct path path; 4005f5beed75SAl Viro struct qstr last; 4006f5beed75SAl Viro int type; 40071da177e4SLinus Torvalds struct inode *inode = NULL; 4008b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40095d18f813SJeff Layton unsigned int lookup_flags = 0; 40105d18f813SJeff Layton retry: 4011f5beed75SAl Viro name = user_path_parent(dfd, pathname, 4012f5beed75SAl Viro &path, &last, &type, lookup_flags); 401391a27b2aSJeff Layton if (IS_ERR(name)) 401491a27b2aSJeff Layton return PTR_ERR(name); 40152ad94ae6SAl Viro 40161da177e4SLinus Torvalds error = -EISDIR; 4017f5beed75SAl Viro if (type != LAST_NORM) 40181da177e4SLinus Torvalds goto exit1; 40190612d9fbSOGAWA Hirofumi 4020f5beed75SAl Viro error = mnt_want_write(path.mnt); 4021c30dabfeSJan Kara if (error) 4022c30dabfeSJan Kara goto exit1; 4023b21996e3SJ. Bruce Fields retry_deleg: 40245955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4025f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40261da177e4SLinus Torvalds error = PTR_ERR(dentry); 40271da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40281da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4029f5beed75SAl Viro if (last.name[last.len]) 403050338b88STörök Edwin goto slashes; 40311da177e4SLinus Torvalds inode = dentry->d_inode; 4032b18825a7SDavid Howells if (d_is_negative(dentry)) 4033e6bc45d6STheodore Ts'o goto slashes; 40347de9c6eeSAl Viro ihold(inode); 4035f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4036be6d3e56SKentaro Takeda if (error) 4037c30dabfeSJan Kara goto exit2; 4038f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40391da177e4SLinus Torvalds exit2: 40401da177e4SLinus Torvalds dput(dentry); 40411da177e4SLinus Torvalds } 40425955102cSAl Viro inode_unlock(path.dentry->d_inode); 40431da177e4SLinus Torvalds if (inode) 40441da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4045b21996e3SJ. Bruce Fields inode = NULL; 4046b21996e3SJ. Bruce Fields if (delegated_inode) { 40475a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4048b21996e3SJ. Bruce Fields if (!error) 4049b21996e3SJ. Bruce Fields goto retry_deleg; 4050b21996e3SJ. Bruce Fields } 4051f5beed75SAl Viro mnt_drop_write(path.mnt); 40521da177e4SLinus Torvalds exit1: 4053f5beed75SAl Viro path_put(&path); 40541da177e4SLinus Torvalds putname(name); 40555d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40565d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40575d18f813SJeff Layton inode = NULL; 40585d18f813SJeff Layton goto retry; 40595d18f813SJeff Layton } 40601da177e4SLinus Torvalds return error; 40611da177e4SLinus Torvalds 40621da177e4SLinus Torvalds slashes: 4063b18825a7SDavid Howells if (d_is_negative(dentry)) 4064b18825a7SDavid Howells error = -ENOENT; 406544b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4066b18825a7SDavid Howells error = -EISDIR; 4067b18825a7SDavid Howells else 4068b18825a7SDavid Howells error = -ENOTDIR; 40691da177e4SLinus Torvalds goto exit2; 40701da177e4SLinus Torvalds } 40711da177e4SLinus Torvalds 40722e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40735590ff0dSUlrich Drepper { 40745590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40755590ff0dSUlrich Drepper return -EINVAL; 40765590ff0dSUlrich Drepper 40775590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40785590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40795590ff0dSUlrich Drepper 40805590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 40815590ff0dSUlrich Drepper } 40825590ff0dSUlrich Drepper 40833480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40845590ff0dSUlrich Drepper { 40855590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 40865590ff0dSUlrich Drepper } 40875590ff0dSUlrich Drepper 4088db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40891da177e4SLinus Torvalds { 4090a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40911da177e4SLinus Torvalds 40921da177e4SLinus Torvalds if (error) 40931da177e4SLinus Torvalds return error; 40941da177e4SLinus Torvalds 4095acfa4380SAl Viro if (!dir->i_op->symlink) 40961da177e4SLinus Torvalds return -EPERM; 40971da177e4SLinus Torvalds 40981da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40991da177e4SLinus Torvalds if (error) 41001da177e4SLinus Torvalds return error; 41011da177e4SLinus Torvalds 41021da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4103a74574aaSStephen Smalley if (!error) 4104f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41051da177e4SLinus Torvalds return error; 41061da177e4SLinus Torvalds } 41074d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41081da177e4SLinus Torvalds 41092e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 41102e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41111da177e4SLinus Torvalds { 41122ad94ae6SAl Viro int error; 411391a27b2aSJeff Layton struct filename *from; 41146902d925SDave Hansen struct dentry *dentry; 4115dae6ad8fSAl Viro struct path path; 4116f46d3567SJeff Layton unsigned int lookup_flags = 0; 41171da177e4SLinus Torvalds 41181da177e4SLinus Torvalds from = getname(oldname); 41191da177e4SLinus Torvalds if (IS_ERR(from)) 41201da177e4SLinus Torvalds return PTR_ERR(from); 4121f46d3567SJeff Layton retry: 4122f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41231da177e4SLinus Torvalds error = PTR_ERR(dentry); 41246902d925SDave Hansen if (IS_ERR(dentry)) 4125dae6ad8fSAl Viro goto out_putname; 41266902d925SDave Hansen 412791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4128a8104a9fSAl Viro if (!error) 412991a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4130921a1650SAl Viro done_path_create(&path, dentry); 4131f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4132f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4133f46d3567SJeff Layton goto retry; 4134f46d3567SJeff Layton } 41356902d925SDave Hansen out_putname: 41361da177e4SLinus Torvalds putname(from); 41371da177e4SLinus Torvalds return error; 41381da177e4SLinus Torvalds } 41391da177e4SLinus Torvalds 41403480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41415590ff0dSUlrich Drepper { 41425590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41435590ff0dSUlrich Drepper } 41445590ff0dSUlrich Drepper 4145146a8595SJ. Bruce Fields /** 4146146a8595SJ. Bruce Fields * vfs_link - create a new link 4147146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4148146a8595SJ. Bruce Fields * @dir: new parent 4149146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4150146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4151146a8595SJ. Bruce Fields * 4152146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4153146a8595SJ. Bruce Fields * 4154146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4155146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4156146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4157146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4158146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4159146a8595SJ. Bruce Fields * 4160146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4161146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4162146a8595SJ. Bruce Fields * to be NFS exported. 4163146a8595SJ. Bruce Fields */ 4164146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41651da177e4SLinus Torvalds { 41661da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41678de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41681da177e4SLinus Torvalds int error; 41691da177e4SLinus Torvalds 41701da177e4SLinus Torvalds if (!inode) 41711da177e4SLinus Torvalds return -ENOENT; 41721da177e4SLinus Torvalds 4173a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41741da177e4SLinus Torvalds if (error) 41751da177e4SLinus Torvalds return error; 41761da177e4SLinus Torvalds 41771da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41781da177e4SLinus Torvalds return -EXDEV; 41791da177e4SLinus Torvalds 41801da177e4SLinus Torvalds /* 41811da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41821da177e4SLinus Torvalds */ 41831da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41841da177e4SLinus Torvalds return -EPERM; 4185acfa4380SAl Viro if (!dir->i_op->link) 41861da177e4SLinus Torvalds return -EPERM; 41877e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41881da177e4SLinus Torvalds return -EPERM; 41891da177e4SLinus Torvalds 41901da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41911da177e4SLinus Torvalds if (error) 41921da177e4SLinus Torvalds return error; 41931da177e4SLinus Torvalds 41945955102cSAl Viro inode_lock(inode); 4195aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4196f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4197aae8a97dSAneesh Kumar K.V error = -ENOENT; 41988de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41998de52778SAl Viro error = -EMLINK; 4200146a8595SJ. Bruce Fields else { 4201146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4202146a8595SJ. Bruce Fields if (!error) 42031da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4204146a8595SJ. Bruce Fields } 4205f4e0c30cSAl Viro 4206f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4207f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4208f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4209f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4210f4e0c30cSAl Viro } 42115955102cSAl Viro inode_unlock(inode); 4212e31e14ecSStephen Smalley if (!error) 42137e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42141da177e4SLinus Torvalds return error; 42151da177e4SLinus Torvalds } 42164d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42171da177e4SLinus Torvalds 42181da177e4SLinus Torvalds /* 42191da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42201da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42211da177e4SLinus Torvalds * newname. --KAB 42221da177e4SLinus Torvalds * 42231da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42241da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42251da177e4SLinus Torvalds * and other special files. --ADM 42261da177e4SLinus Torvalds */ 42272e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42282e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42291da177e4SLinus Torvalds { 42301da177e4SLinus Torvalds struct dentry *new_dentry; 4231dae6ad8fSAl Viro struct path old_path, new_path; 4232146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 423311a7b371SAneesh Kumar K.V int how = 0; 42341da177e4SLinus Torvalds int error; 42351da177e4SLinus Torvalds 423611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4237c04030e1SUlrich Drepper return -EINVAL; 423811a7b371SAneesh Kumar K.V /* 4239f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4240f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4241f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 424211a7b371SAneesh Kumar K.V */ 4243f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4244f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4245f0cc6ffbSLinus Torvalds return -ENOENT; 424611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4247f0cc6ffbSLinus Torvalds } 4248c04030e1SUlrich Drepper 424911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 425011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4251442e31caSJeff Layton retry: 425211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42531da177e4SLinus Torvalds if (error) 42542ad94ae6SAl Viro return error; 42552ad94ae6SAl Viro 4256442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4257442e31caSJeff Layton (how & LOOKUP_REVAL)); 42581da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42596902d925SDave Hansen if (IS_ERR(new_dentry)) 4260dae6ad8fSAl Viro goto out; 4261dae6ad8fSAl Viro 4262dae6ad8fSAl Viro error = -EXDEV; 4263dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4264dae6ad8fSAl Viro goto out_dput; 4265800179c9SKees Cook error = may_linkat(&old_path); 4266800179c9SKees Cook if (unlikely(error)) 4267800179c9SKees Cook goto out_dput; 4268dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4269be6d3e56SKentaro Takeda if (error) 4270a8104a9fSAl Viro goto out_dput; 4271146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 427275c3f29dSDave Hansen out_dput: 4273921a1650SAl Viro done_path_create(&new_path, new_dentry); 4274146a8595SJ. Bruce Fields if (delegated_inode) { 4275146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4276d22e6338SOleg Drokin if (!error) { 4277d22e6338SOleg Drokin path_put(&old_path); 4278146a8595SJ. Bruce Fields goto retry; 4279146a8595SJ. Bruce Fields } 4280d22e6338SOleg Drokin } 4281442e31caSJeff Layton if (retry_estale(error, how)) { 4282d22e6338SOleg Drokin path_put(&old_path); 4283442e31caSJeff Layton how |= LOOKUP_REVAL; 4284442e31caSJeff Layton goto retry; 4285442e31caSJeff Layton } 42861da177e4SLinus Torvalds out: 42872d8f3038SAl Viro path_put(&old_path); 42881da177e4SLinus Torvalds 42891da177e4SLinus Torvalds return error; 42901da177e4SLinus Torvalds } 42911da177e4SLinus Torvalds 42923480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42935590ff0dSUlrich Drepper { 4294c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42955590ff0dSUlrich Drepper } 42965590ff0dSUlrich Drepper 4297bc27027aSMiklos Szeredi /** 4298bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4299bc27027aSMiklos Szeredi * @old_dir: parent of source 4300bc27027aSMiklos Szeredi * @old_dentry: source 4301bc27027aSMiklos Szeredi * @new_dir: parent of destination 4302bc27027aSMiklos Szeredi * @new_dentry: destination 4303bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4304520c8b16SMiklos Szeredi * @flags: rename flags 4305bc27027aSMiklos Szeredi * 4306bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4307bc27027aSMiklos Szeredi * 4308bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4309bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4310bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4311bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4312bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4313bc27027aSMiklos Szeredi * so. 4314bc27027aSMiklos Szeredi * 4315bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4316bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4317bc27027aSMiklos Szeredi * to be NFS exported. 4318bc27027aSMiklos Szeredi * 43191da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43201da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43211da177e4SLinus Torvalds * Problems: 4322d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43231da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43241da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4325a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43261da177e4SLinus Torvalds * story. 43276cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43286cedba89SJ. Bruce Fields * and source (if it is not a directory). 43291b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43301da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43311da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4332a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43331da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43341da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43351da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4336a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43371da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43381da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43391da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4340e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43411b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43421da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4343c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43441da177e4SLinus Torvalds * locking]. 43451da177e4SLinus Torvalds */ 43461da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43478e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4348520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43491da177e4SLinus Torvalds { 43501da177e4SLinus Torvalds int error; 4351bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 435259b0df21SEric Paris const unsigned char *old_name; 4353bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4354bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4355da1ce067SMiklos Szeredi bool new_is_dir = false; 4356da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 43571da177e4SLinus Torvalds 43589409e22aSMiklos Szeredi /* 43599409e22aSMiklos Szeredi * Check source == target. 43609409e22aSMiklos Szeredi * On overlayfs need to look at underlying inodes. 43619409e22aSMiklos Szeredi */ 43629409e22aSMiklos Szeredi if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) 43631da177e4SLinus Torvalds return 0; 43641da177e4SLinus Torvalds 43651da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43661da177e4SLinus Torvalds if (error) 43671da177e4SLinus Torvalds return error; 43681da177e4SLinus Torvalds 4369da1ce067SMiklos Szeredi if (!target) { 4370a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4371da1ce067SMiklos Szeredi } else { 4372da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4373da1ce067SMiklos Szeredi 4374da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43751da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4376da1ce067SMiklos Szeredi else 4377da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4378da1ce067SMiklos Szeredi } 43791da177e4SLinus Torvalds if (error) 43801da177e4SLinus Torvalds return error; 43811da177e4SLinus Torvalds 43827177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 43831da177e4SLinus Torvalds return -EPERM; 43841da177e4SLinus Torvalds 4385520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4386520c8b16SMiklos Szeredi return -EINVAL; 4387520c8b16SMiklos Szeredi 4388bc27027aSMiklos Szeredi /* 4389bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4390bc27027aSMiklos Szeredi * we'll need to flip '..'. 4391bc27027aSMiklos Szeredi */ 4392da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4393da1ce067SMiklos Szeredi if (is_dir) { 4394bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4395bc27027aSMiklos Szeredi if (error) 4396bc27027aSMiklos Szeredi return error; 4397bc27027aSMiklos Szeredi } 4398da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4399da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4400da1ce067SMiklos Szeredi if (error) 4401da1ce067SMiklos Szeredi return error; 4402da1ce067SMiklos Szeredi } 4403da1ce067SMiklos Szeredi } 44040eeca283SRobert Love 44050b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44060b3974ebSMiklos Szeredi flags); 4407bc27027aSMiklos Szeredi if (error) 4408bc27027aSMiklos Szeredi return error; 4409bc27027aSMiklos Szeredi 4410bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4411bc27027aSMiklos Szeredi dget(new_dentry); 4412da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4413bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4414bc27027aSMiklos Szeredi else if (target) 44155955102cSAl Viro inode_lock(target); 4416bc27027aSMiklos Szeredi 4417bc27027aSMiklos Szeredi error = -EBUSY; 44187af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4419bc27027aSMiklos Szeredi goto out; 4420bc27027aSMiklos Szeredi 4421da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4422bc27027aSMiklos Szeredi error = -EMLINK; 4423da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4424bc27027aSMiklos Szeredi goto out; 4425da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4426da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4427da1ce067SMiklos Szeredi goto out; 4428da1ce067SMiklos Szeredi } 4429da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4430bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4431da1ce067SMiklos Szeredi if (!is_dir) { 4432bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4433bc27027aSMiklos Szeredi if (error) 4434bc27027aSMiklos Szeredi goto out; 4435da1ce067SMiklos Szeredi } 4436da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4437bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4438bc27027aSMiklos Szeredi if (error) 4439bc27027aSMiklos Szeredi goto out; 4440bc27027aSMiklos Szeredi } 44417177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4442520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4443520c8b16SMiklos Szeredi new_dir, new_dentry); 4444520c8b16SMiklos Szeredi } else { 44457177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4446520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4447520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4448520c8b16SMiklos Szeredi } 4449bc27027aSMiklos Szeredi if (error) 4450bc27027aSMiklos Szeredi goto out; 4451bc27027aSMiklos Szeredi 4452da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44531da177e4SLinus Torvalds if (is_dir) 4454bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4455bc27027aSMiklos Szeredi dont_mount(new_dentry); 44568ed936b5SEric W. Biederman detach_mounts(new_dentry); 4457bc27027aSMiklos Szeredi } 4458da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4459da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4460bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4461da1ce067SMiklos Szeredi else 4462da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4463da1ce067SMiklos Szeredi } 4464bc27027aSMiklos Szeredi out: 4465da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4466bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4467bc27027aSMiklos Szeredi else if (target) 44685955102cSAl Viro inode_unlock(target); 4469bc27027aSMiklos Szeredi dput(new_dentry); 4470da1ce067SMiklos Szeredi if (!error) { 4471123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4472da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4473da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4474da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4475da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4476da1ce067SMiklos Szeredi } 4477da1ce067SMiklos Szeredi } 44780eeca283SRobert Love fsnotify_oldname_free(old_name); 44790eeca283SRobert Love 44801da177e4SLinus Torvalds return error; 44811da177e4SLinus Torvalds } 44824d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44831da177e4SLinus Torvalds 4484520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4485520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44861da177e4SLinus Torvalds { 44871da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44881da177e4SLinus Torvalds struct dentry *trap; 4489f5beed75SAl Viro struct path old_path, new_path; 4490f5beed75SAl Viro struct qstr old_last, new_last; 4491f5beed75SAl Viro int old_type, new_type; 44928e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 449391a27b2aSJeff Layton struct filename *from; 449491a27b2aSJeff Layton struct filename *to; 4495f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4496c6a94284SJeff Layton bool should_retry = false; 44972ad94ae6SAl Viro int error; 4498520c8b16SMiklos Szeredi 44990d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4500da1ce067SMiklos Szeredi return -EINVAL; 4501da1ce067SMiklos Szeredi 45020d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 45030d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4504520c8b16SMiklos Szeredi return -EINVAL; 4505520c8b16SMiklos Szeredi 45060d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 45070d7a8555SMiklos Szeredi return -EPERM; 45080d7a8555SMiklos Szeredi 4509f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4510f5beed75SAl Viro target_flags = 0; 4511f5beed75SAl Viro 4512c6a94284SJeff Layton retry: 4513f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4514f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 451591a27b2aSJeff Layton if (IS_ERR(from)) { 451691a27b2aSJeff Layton error = PTR_ERR(from); 45171da177e4SLinus Torvalds goto exit; 451891a27b2aSJeff Layton } 45191da177e4SLinus Torvalds 4520f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4521f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 452291a27b2aSJeff Layton if (IS_ERR(to)) { 452391a27b2aSJeff Layton error = PTR_ERR(to); 45241da177e4SLinus Torvalds goto exit1; 452591a27b2aSJeff Layton } 45261da177e4SLinus Torvalds 45271da177e4SLinus Torvalds error = -EXDEV; 4528f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45291da177e4SLinus Torvalds goto exit2; 45301da177e4SLinus Torvalds 45311da177e4SLinus Torvalds error = -EBUSY; 4532f5beed75SAl Viro if (old_type != LAST_NORM) 45331da177e4SLinus Torvalds goto exit2; 45341da177e4SLinus Torvalds 45350a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45360a7c3937SMiklos Szeredi error = -EEXIST; 4537f5beed75SAl Viro if (new_type != LAST_NORM) 45381da177e4SLinus Torvalds goto exit2; 45391da177e4SLinus Torvalds 4540f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4541c30dabfeSJan Kara if (error) 4542c30dabfeSJan Kara goto exit2; 4543c30dabfeSJan Kara 45448e6d782cSJ. Bruce Fields retry_deleg: 4545f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45461da177e4SLinus Torvalds 4547f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45481da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45491da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45501da177e4SLinus Torvalds goto exit3; 45511da177e4SLinus Torvalds /* source must exist */ 45521da177e4SLinus Torvalds error = -ENOENT; 4553b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45541da177e4SLinus Torvalds goto exit4; 4555f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45561da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45571da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45581da177e4SLinus Torvalds goto exit4; 45590a7c3937SMiklos Szeredi error = -EEXIST; 45600a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45610a7c3937SMiklos Szeredi goto exit5; 4562da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4563da1ce067SMiklos Szeredi error = -ENOENT; 4564da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4565da1ce067SMiklos Szeredi goto exit5; 4566da1ce067SMiklos Szeredi 4567da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4568da1ce067SMiklos Szeredi error = -ENOTDIR; 4569f5beed75SAl Viro if (new_last.name[new_last.len]) 4570da1ce067SMiklos Szeredi goto exit5; 4571da1ce067SMiklos Szeredi } 4572da1ce067SMiklos Szeredi } 45730a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45740a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45750a7c3937SMiklos Szeredi error = -ENOTDIR; 4576f5beed75SAl Viro if (old_last.name[old_last.len]) 45770a7c3937SMiklos Szeredi goto exit5; 4578f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45790a7c3937SMiklos Szeredi goto exit5; 45800a7c3937SMiklos Szeredi } 45810a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45820a7c3937SMiklos Szeredi error = -EINVAL; 45830a7c3937SMiklos Szeredi if (old_dentry == trap) 45840a7c3937SMiklos Szeredi goto exit5; 45851da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4586da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45871da177e4SLinus Torvalds error = -ENOTEMPTY; 45881da177e4SLinus Torvalds if (new_dentry == trap) 45891da177e4SLinus Torvalds goto exit5; 45901da177e4SLinus Torvalds 4591f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4592f5beed75SAl Viro &new_path, new_dentry, flags); 4593be6d3e56SKentaro Takeda if (error) 4594c30dabfeSJan Kara goto exit5; 4595f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4596f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4597520c8b16SMiklos Szeredi &delegated_inode, flags); 45981da177e4SLinus Torvalds exit5: 45991da177e4SLinus Torvalds dput(new_dentry); 46001da177e4SLinus Torvalds exit4: 46011da177e4SLinus Torvalds dput(old_dentry); 46021da177e4SLinus Torvalds exit3: 4603f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 46048e6d782cSJ. Bruce Fields if (delegated_inode) { 46058e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 46068e6d782cSJ. Bruce Fields if (!error) 46078e6d782cSJ. Bruce Fields goto retry_deleg; 46088e6d782cSJ. Bruce Fields } 4609f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46101da177e4SLinus Torvalds exit2: 4611c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4612c6a94284SJeff Layton should_retry = true; 4613f5beed75SAl Viro path_put(&new_path); 46142ad94ae6SAl Viro putname(to); 46151da177e4SLinus Torvalds exit1: 4616f5beed75SAl Viro path_put(&old_path); 46171da177e4SLinus Torvalds putname(from); 4618c6a94284SJeff Layton if (should_retry) { 4619c6a94284SJeff Layton should_retry = false; 4620c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4621c6a94284SJeff Layton goto retry; 4622c6a94284SJeff Layton } 46232ad94ae6SAl Viro exit: 46241da177e4SLinus Torvalds return error; 46251da177e4SLinus Torvalds } 46261da177e4SLinus Torvalds 4627520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4628520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4629520c8b16SMiklos Szeredi { 4630520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4631520c8b16SMiklos Szeredi } 4632520c8b16SMiklos Szeredi 4633a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46345590ff0dSUlrich Drepper { 4635520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46365590ff0dSUlrich Drepper } 46375590ff0dSUlrich Drepper 4638787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4639787fb6bcSMiklos Szeredi { 4640787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4641787fb6bcSMiklos Szeredi if (error) 4642787fb6bcSMiklos Szeredi return error; 4643787fb6bcSMiklos Szeredi 4644787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4645787fb6bcSMiklos Szeredi return -EPERM; 4646787fb6bcSMiklos Szeredi 4647787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4648787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4649787fb6bcSMiklos Szeredi } 4650787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4651787fb6bcSMiklos Szeredi 46525d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46531da177e4SLinus Torvalds { 46545d826c84SAl Viro int len = PTR_ERR(link); 46551da177e4SLinus Torvalds if (IS_ERR(link)) 46561da177e4SLinus Torvalds goto out; 46571da177e4SLinus Torvalds 46581da177e4SLinus Torvalds len = strlen(link); 46591da177e4SLinus Torvalds if (len > (unsigned) buflen) 46601da177e4SLinus Torvalds len = buflen; 46611da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46621da177e4SLinus Torvalds len = -EFAULT; 46631da177e4SLinus Torvalds out: 46641da177e4SLinus Torvalds return len; 46651da177e4SLinus Torvalds } 46661da177e4SLinus Torvalds 46671da177e4SLinus Torvalds /* 46681da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46696b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46706b255391SAl Viro * for any given inode is up to filesystem. 46711da177e4SLinus Torvalds */ 46721da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 46731da177e4SLinus Torvalds { 4674fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46755f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46765f2c4179SAl Viro const char *link = inode->i_link; 4677694a1764SMarcin Slusarz int res; 4678cc314eefSLinus Torvalds 4679d4dee48bSAl Viro if (!link) { 4680fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4681680baacbSAl Viro if (IS_ERR(link)) 4682680baacbSAl Viro return PTR_ERR(link); 4683d4dee48bSAl Viro } 4684680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4685fceef393SAl Viro do_delayed_call(&done); 4686694a1764SMarcin Slusarz return res; 46871da177e4SLinus Torvalds } 46884d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 46891da177e4SLinus Torvalds 46901da177e4SLinus Torvalds /* get the link contents into pagecache */ 46916b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4692fceef393SAl Viro struct delayed_call *callback) 46931da177e4SLinus Torvalds { 4694ebd09abbSDuane Griffin char *kaddr; 46951da177e4SLinus Torvalds struct page *page; 46966b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46976b255391SAl Viro 4698d3883d4fSAl Viro if (!dentry) { 4699d3883d4fSAl Viro page = find_get_page(mapping, 0); 4700d3883d4fSAl Viro if (!page) 47016b255391SAl Viro return ERR_PTR(-ECHILD); 4702d3883d4fSAl Viro if (!PageUptodate(page)) { 4703d3883d4fSAl Viro put_page(page); 4704d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4705d3883d4fSAl Viro } 4706d3883d4fSAl Viro } else { 4707090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47081da177e4SLinus Torvalds if (IS_ERR(page)) 47096fe6900eSNick Piggin return (char*)page; 4710d3883d4fSAl Viro } 4711fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 471221fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 471321fc61c7SAl Viro kaddr = page_address(page); 47146b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4715ebd09abbSDuane Griffin return kaddr; 47161da177e4SLinus Torvalds } 47171da177e4SLinus Torvalds 47186b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47191da177e4SLinus Torvalds 4720fceef393SAl Viro void page_put_link(void *arg) 47211da177e4SLinus Torvalds { 4722fceef393SAl Viro put_page(arg); 47231da177e4SLinus Torvalds } 47244d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47251da177e4SLinus Torvalds 4726aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4727aa80deabSAl Viro { 4728fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47296b255391SAl Viro int res = readlink_copy(buffer, buflen, 47306b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4731fceef393SAl Viro &done)); 4732fceef393SAl Viro do_delayed_call(&done); 4733aa80deabSAl Viro return res; 4734aa80deabSAl Viro } 4735aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4736aa80deabSAl Viro 473754566b2cSNick Piggin /* 473854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 473954566b2cSNick Piggin */ 474054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47411da177e4SLinus Torvalds { 47421da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47430adb25d2SKirill Korotaev struct page *page; 4744afddba49SNick Piggin void *fsdata; 4745beb497abSDmitriy Monakhov int err; 474654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 474754566b2cSNick Piggin if (nofs) 474854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47491da177e4SLinus Torvalds 47507e53cac4SNeilBrown retry: 4751afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 475254566b2cSNick Piggin flags, &page, &fsdata); 47531da177e4SLinus Torvalds if (err) 4754afddba49SNick Piggin goto fail; 4755afddba49SNick Piggin 475621fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4757afddba49SNick Piggin 4758afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4759afddba49SNick Piggin page, fsdata); 47601da177e4SLinus Torvalds if (err < 0) 47611da177e4SLinus Torvalds goto fail; 4762afddba49SNick Piggin if (err < len-1) 4763afddba49SNick Piggin goto retry; 4764afddba49SNick Piggin 47651da177e4SLinus Torvalds mark_inode_dirty(inode); 47661da177e4SLinus Torvalds return 0; 47671da177e4SLinus Torvalds fail: 47681da177e4SLinus Torvalds return err; 47691da177e4SLinus Torvalds } 47704d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47711da177e4SLinus Torvalds 47720adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47730adb25d2SKirill Korotaev { 47740adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4775c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47760adb25d2SKirill Korotaev } 47774d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47780adb25d2SKirill Korotaev 477992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47801da177e4SLinus Torvalds .readlink = generic_readlink, 47816b255391SAl Viro .get_link = page_get_link, 47821da177e4SLinus Torvalds }; 47831da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4784