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> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 12191a27b2aSJeff Layton void final_putname(struct filename *name) 1221da177e4SLinus Torvalds { 1237950e385SJeff Layton if (name->separate) { 12491a27b2aSJeff Layton __putname(name->name); 12591a27b2aSJeff Layton kfree(name); 1267950e385SJeff Layton } else { 1277950e385SJeff Layton __putname(name); 12891a27b2aSJeff Layton } 1297950e385SJeff Layton } 1307950e385SJeff Layton 1317950e385SJeff Layton #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) 13291a27b2aSJeff Layton 13391a27b2aSJeff Layton static struct filename * 13491a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 13591a27b2aSJeff Layton { 13691a27b2aSJeff Layton struct filename *result, *err; 1373f9f0aa6SLinus Torvalds int len; 1387950e385SJeff Layton long max; 1397950e385SJeff Layton char *kname; 1401da177e4SLinus Torvalds 1417ac86265SJeff Layton result = audit_reusename(filename); 1427ac86265SJeff Layton if (result) 1437ac86265SJeff Layton return result; 1447ac86265SJeff Layton 1457950e385SJeff Layton result = __getname(); 1463f9f0aa6SLinus Torvalds if (unlikely(!result)) 1474043cde8SEric Paris return ERR_PTR(-ENOMEM); 1481da177e4SLinus Torvalds 1497950e385SJeff Layton /* 1507950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1517950e385SJeff Layton * allocation 1527950e385SJeff Layton */ 1537950e385SJeff Layton kname = (char *)result + sizeof(*result); 15491a27b2aSJeff Layton result->name = kname; 1557950e385SJeff Layton result->separate = false; 1567950e385SJeff Layton max = EMBEDDED_NAME_MAX; 1577950e385SJeff Layton 1587950e385SJeff Layton recopy: 1597950e385SJeff Layton len = strncpy_from_user(kname, filename, max); 16091a27b2aSJeff Layton if (unlikely(len < 0)) { 1613f9f0aa6SLinus Torvalds err = ERR_PTR(len); 1623f9f0aa6SLinus Torvalds goto error; 16391a27b2aSJeff Layton } 1643f9f0aa6SLinus Torvalds 1657950e385SJeff Layton /* 1667950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1677950e385SJeff Layton * separate struct filename so we can dedicate the entire 1687950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1697950e385SJeff Layton * userland. 1707950e385SJeff Layton */ 1717950e385SJeff Layton if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { 1727950e385SJeff Layton kname = (char *)result; 1737950e385SJeff Layton 1747950e385SJeff Layton result = kzalloc(sizeof(*result), GFP_KERNEL); 1757950e385SJeff Layton if (!result) { 1767950e385SJeff Layton err = ERR_PTR(-ENOMEM); 1777950e385SJeff Layton result = (struct filename *)kname; 1787950e385SJeff Layton goto error; 1797950e385SJeff Layton } 1807950e385SJeff Layton result->name = kname; 1817950e385SJeff Layton result->separate = true; 1827950e385SJeff Layton max = PATH_MAX; 1837950e385SJeff Layton goto recopy; 1847950e385SJeff Layton } 1857950e385SJeff Layton 1863f9f0aa6SLinus Torvalds /* The empty path is special. */ 1873f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1883f9f0aa6SLinus Torvalds if (empty) 1891fa1e7f6SAndy Whitcroft *empty = 1; 1903f9f0aa6SLinus Torvalds err = ERR_PTR(-ENOENT); 1913f9f0aa6SLinus Torvalds if (!(flags & LOOKUP_EMPTY)) 1923f9f0aa6SLinus Torvalds goto error; 1931da177e4SLinus Torvalds } 1943f9f0aa6SLinus Torvalds 1953f9f0aa6SLinus Torvalds err = ERR_PTR(-ENAMETOOLONG); 1967950e385SJeff Layton if (unlikely(len >= PATH_MAX)) 1977950e385SJeff Layton goto error; 1987950e385SJeff Layton 1997950e385SJeff Layton result->uptr = filename; 200c4ad8f98SLinus Torvalds result->aname = NULL; 2011da177e4SLinus Torvalds audit_getname(result); 2021da177e4SLinus Torvalds return result; 2031da177e4SLinus Torvalds 2043f9f0aa6SLinus Torvalds error: 2057950e385SJeff Layton final_putname(result); 2063f9f0aa6SLinus Torvalds return err; 2073f9f0aa6SLinus Torvalds } 2083f9f0aa6SLinus Torvalds 20991a27b2aSJeff Layton struct filename * 21091a27b2aSJeff Layton getname(const char __user * filename) 211f52e0c11SAl Viro { 212f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 213f52e0c11SAl Viro } 214f52e0c11SAl Viro 215c4ad8f98SLinus Torvalds /* 216c4ad8f98SLinus Torvalds * The "getname_kernel()" interface doesn't do pathnames longer 217c4ad8f98SLinus Torvalds * than EMBEDDED_NAME_MAX. Deal with it - you're a kernel user. 218c4ad8f98SLinus Torvalds */ 219c4ad8f98SLinus Torvalds struct filename * 220c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 221c4ad8f98SLinus Torvalds { 222c4ad8f98SLinus Torvalds struct filename *result; 223c4ad8f98SLinus Torvalds char *kname; 224c4ad8f98SLinus Torvalds int len; 225c4ad8f98SLinus Torvalds 226c4ad8f98SLinus Torvalds len = strlen(filename); 227c4ad8f98SLinus Torvalds if (len >= EMBEDDED_NAME_MAX) 228c4ad8f98SLinus Torvalds return ERR_PTR(-ENAMETOOLONG); 229c4ad8f98SLinus Torvalds 230c4ad8f98SLinus Torvalds result = __getname(); 231c4ad8f98SLinus Torvalds if (unlikely(!result)) 232c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 233c4ad8f98SLinus Torvalds 234c4ad8f98SLinus Torvalds kname = (char *)result + sizeof(*result); 235c4ad8f98SLinus Torvalds result->name = kname; 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 238c4ad8f98SLinus Torvalds result->separate = false; 239c4ad8f98SLinus Torvalds 240c4ad8f98SLinus Torvalds strlcpy(kname, filename, EMBEDDED_NAME_MAX); 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 2441da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 24591a27b2aSJeff Layton void putname(struct filename *name) 2461da177e4SLinus Torvalds { 2475ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 24891a27b2aSJeff Layton return audit_putname(name); 24991a27b2aSJeff Layton final_putname(name); 2501da177e4SLinus Torvalds } 2511da177e4SLinus Torvalds #endif 2521da177e4SLinus Torvalds 253e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 254e77819e5SLinus Torvalds { 25584635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 256e77819e5SLinus Torvalds struct posix_acl *acl; 257e77819e5SLinus Torvalds 258e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2593567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2603567866bSAl Viro if (!acl) 261e77819e5SLinus Torvalds return -EAGAIN; 2623567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2633567866bSAl Viro if (acl == ACL_NOT_CACHED) 264e77819e5SLinus Torvalds return -ECHILD; 265206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 266e77819e5SLinus Torvalds } 267e77819e5SLinus Torvalds 2682982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2694e34e719SChristoph Hellwig if (IS_ERR(acl)) 2704e34e719SChristoph Hellwig return PTR_ERR(acl); 271e77819e5SLinus Torvalds if (acl) { 272e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 273e77819e5SLinus Torvalds posix_acl_release(acl); 274e77819e5SLinus Torvalds return error; 275e77819e5SLinus Torvalds } 27684635d68SLinus Torvalds #endif 277e77819e5SLinus Torvalds 278e77819e5SLinus Torvalds return -EAGAIN; 279e77819e5SLinus Torvalds } 280e77819e5SLinus Torvalds 2815909ccaaSLinus Torvalds /* 282948409c7SAndreas Gruenbacher * This does the basic permission checking 2835909ccaaSLinus Torvalds */ 2847e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2855909ccaaSLinus Torvalds { 28626cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2875909ccaaSLinus Torvalds 2888e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2895909ccaaSLinus Torvalds mode >>= 6; 2905909ccaaSLinus Torvalds else { 291e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2927e40145eSAl Viro int error = check_acl(inode, mask); 2935909ccaaSLinus Torvalds if (error != -EAGAIN) 2945909ccaaSLinus Torvalds return error; 2955909ccaaSLinus Torvalds } 2965909ccaaSLinus Torvalds 2975909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2985909ccaaSLinus Torvalds mode >>= 3; 2995909ccaaSLinus Torvalds } 3005909ccaaSLinus Torvalds 3015909ccaaSLinus Torvalds /* 3025909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3035909ccaaSLinus Torvalds */ 3049c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3055909ccaaSLinus Torvalds return 0; 3065909ccaaSLinus Torvalds return -EACCES; 3075909ccaaSLinus Torvalds } 3081da177e4SLinus Torvalds 3091da177e4SLinus Torvalds /** 3101da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3111da177e4SLinus Torvalds * @inode: inode to check access rights for 3128fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3131da177e4SLinus Torvalds * 3141da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3151da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3161da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 317b74c79e9SNick Piggin * are used for other things. 318b74c79e9SNick Piggin * 319b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 320b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 321b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3221da177e4SLinus Torvalds */ 3232830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3241da177e4SLinus Torvalds { 3255909ccaaSLinus Torvalds int ret; 3261da177e4SLinus Torvalds 3271da177e4SLinus Torvalds /* 328948409c7SAndreas Gruenbacher * Do the basic permission checks. 3291da177e4SLinus Torvalds */ 3307e40145eSAl Viro ret = acl_permission_check(inode, mask); 3315909ccaaSLinus Torvalds if (ret != -EACCES) 3325909ccaaSLinus Torvalds return ret; 3331da177e4SLinus Torvalds 334d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 335d594e7ecSAl Viro /* DACs are overridable for directories */ 33623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 337d594e7ecSAl Viro return 0; 338d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 33923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34023adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 341d594e7ecSAl Viro return 0; 342d594e7ecSAl Viro return -EACCES; 343d594e7ecSAl Viro } 3441da177e4SLinus Torvalds /* 3451da177e4SLinus Torvalds * Read/write DACs are always overridable. 346d594e7ecSAl Viro * Executable DACs are overridable when there is 347d594e7ecSAl Viro * at least one exec bit set. 3481da177e4SLinus Torvalds */ 349d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35023adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3511da177e4SLinus Torvalds return 0; 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds /* 3541da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3551da177e4SLinus Torvalds */ 3567ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 357d594e7ecSAl Viro if (mask == MAY_READ) 35823adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3591da177e4SLinus Torvalds return 0; 3601da177e4SLinus Torvalds 3611da177e4SLinus Torvalds return -EACCES; 3621da177e4SLinus Torvalds } 3634d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3641da177e4SLinus Torvalds 3653ddcd056SLinus Torvalds /* 3663ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3673ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3683ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3693ddcd056SLinus Torvalds * permission function, use the fast case". 3703ddcd056SLinus Torvalds */ 3713ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3723ddcd056SLinus Torvalds { 3733ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3743ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3753ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3763ddcd056SLinus Torvalds 3773ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3783ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3793ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3803ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3813ddcd056SLinus Torvalds } 3823ddcd056SLinus Torvalds return generic_permission(inode, mask); 3833ddcd056SLinus Torvalds } 3843ddcd056SLinus Torvalds 385cb23beb5SChristoph Hellwig /** 3860bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3870bdaea90SDavid Howells * @inode: Inode to check permission on 3880bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 389cb23beb5SChristoph Hellwig * 3900bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 391948409c7SAndreas Gruenbacher * 392948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3930bdaea90SDavid Howells * 3940bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 3950bdaea90SDavid Howells * inode_permission(). 396cb23beb5SChristoph Hellwig */ 3970bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 3981da177e4SLinus Torvalds { 399e6305c43SAl Viro int retval; 4001da177e4SLinus Torvalds 4013ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4021da177e4SLinus Torvalds /* 4031da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4041da177e4SLinus Torvalds */ 4051da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4061da177e4SLinus Torvalds return -EACCES; 4071da177e4SLinus Torvalds } 4081da177e4SLinus Torvalds 4093ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4101da177e4SLinus Torvalds if (retval) 4111da177e4SLinus Torvalds return retval; 4121da177e4SLinus Torvalds 41308ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41408ce5f16SSerge E. Hallyn if (retval) 41508ce5f16SSerge E. Hallyn return retval; 41608ce5f16SSerge E. Hallyn 417d09ca739SEric Paris return security_inode_permission(inode, mask); 4181da177e4SLinus Torvalds } 419bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4201da177e4SLinus Torvalds 421f4d6ff89SAl Viro /** 4220bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4230bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42455852635SRandy Dunlap * @inode: Inode to check permission on 4250bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4260bdaea90SDavid Howells * 4270bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4280bdaea90SDavid Howells */ 4290bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4300bdaea90SDavid Howells { 4310bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4320bdaea90SDavid Howells umode_t mode = inode->i_mode; 4330bdaea90SDavid Howells 4340bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4350bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4360bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4370bdaea90SDavid Howells return -EROFS; 4380bdaea90SDavid Howells } 4390bdaea90SDavid Howells return 0; 4400bdaea90SDavid Howells } 4410bdaea90SDavid Howells 4420bdaea90SDavid Howells /** 4430bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4440bdaea90SDavid Howells * @inode: Inode to check permission on 4450bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4460bdaea90SDavid Howells * 4470bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4480bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4490bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4500bdaea90SDavid Howells * 4510bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4520bdaea90SDavid Howells */ 4530bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4540bdaea90SDavid Howells { 4550bdaea90SDavid Howells int retval; 4560bdaea90SDavid Howells 4570bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4580bdaea90SDavid Howells if (retval) 4590bdaea90SDavid Howells return retval; 4600bdaea90SDavid Howells return __inode_permission(inode, mask); 4610bdaea90SDavid Howells } 4624d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4630bdaea90SDavid Howells 4640bdaea90SDavid Howells /** 4655dd784d0SJan Blunck * path_get - get a reference to a path 4665dd784d0SJan Blunck * @path: path to get the reference to 4675dd784d0SJan Blunck * 4685dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4695dd784d0SJan Blunck */ 470dcf787f3SAl Viro void path_get(const struct path *path) 4715dd784d0SJan Blunck { 4725dd784d0SJan Blunck mntget(path->mnt); 4735dd784d0SJan Blunck dget(path->dentry); 4745dd784d0SJan Blunck } 4755dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4765dd784d0SJan Blunck 4775dd784d0SJan Blunck /** 4781d957f9bSJan Blunck * path_put - put a reference to a path 4791d957f9bSJan Blunck * @path: path to put the reference to 4801d957f9bSJan Blunck * 4811d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4821d957f9bSJan Blunck */ 483dcf787f3SAl Viro void path_put(const struct path *path) 4841da177e4SLinus Torvalds { 4851d957f9bSJan Blunck dput(path->dentry); 4861d957f9bSJan Blunck mntput(path->mnt); 4871da177e4SLinus Torvalds } 4881d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4891da177e4SLinus Torvalds 4901f55a6ecSAl Viro struct nameidata { 4911f55a6ecSAl Viro struct path path; 4921f55a6ecSAl Viro struct qstr last; 4931f55a6ecSAl Viro struct path root; 4941f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4951f55a6ecSAl Viro unsigned int flags; 4961f55a6ecSAl Viro unsigned seq, m_seq; 4971f55a6ecSAl Viro int last_type; 4981f55a6ecSAl Viro unsigned depth; 4991f55a6ecSAl Viro char *saved_names[MAX_NESTED_LINKS + 1]; 5001f55a6ecSAl Viro }; 5011f55a6ecSAl Viro 50219660af7SAl Viro /* 50331e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 50419660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 50519660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 50619660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 50719660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 50819660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 50919660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 51019660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 51131e6b01fSNick Piggin */ 51231e6b01fSNick Piggin 51331e6b01fSNick Piggin /** 51419660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 51519660af7SAl Viro * @nd: nameidata pathwalk data 51619660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 51739191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 51831e6b01fSNick Piggin * 51919660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 52019660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 52119660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 52231e6b01fSNick Piggin */ 52319660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 52431e6b01fSNick Piggin { 52531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 52631e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 52731e6b01fSNick Piggin 52831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 529e5c832d5SLinus Torvalds 530e5c832d5SLinus Torvalds /* 53148a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 53248a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 53348a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 53448a066e7SAl Viro * before returning. Do vfsmount first; if dentry 53548a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 53648a066e7SAl Viro * and rely on dput(NULL) being a no-op. 537e5c832d5SLinus Torvalds */ 53848a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 539e5c832d5SLinus Torvalds return -ECHILD; 540e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 54115570086SLinus Torvalds 54248a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 54348a066e7SAl Viro nd->path.dentry = NULL; 544d870b4a1SAl Viro goto out; 54548a066e7SAl Viro } 54648a066e7SAl Viro 54715570086SLinus Torvalds /* 54815570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 54915570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 55015570086SLinus Torvalds * 55115570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 55215570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 55315570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 55415570086SLinus Torvalds * since we checked the sequence number of the parent after we got 55515570086SLinus Torvalds * the child sequence number. So we know the parent must still 55615570086SLinus Torvalds * be valid if the child sequence number is still valid. 55715570086SLinus Torvalds */ 55819660af7SAl Viro if (!dentry) { 559e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 560e5c832d5SLinus Torvalds goto out; 56119660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 56219660af7SAl Viro } else { 563e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 564e5c832d5SLinus Torvalds goto out; 565e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 566e5c832d5SLinus Torvalds goto drop_dentry; 56719660af7SAl Viro } 568e5c832d5SLinus Torvalds 569e5c832d5SLinus Torvalds /* 570e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 571e5c832d5SLinus Torvalds * still valid and get it if required. 572e5c832d5SLinus Torvalds */ 573e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 574e5c832d5SLinus Torvalds spin_lock(&fs->lock); 575e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 576e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 57731e6b01fSNick Piggin path_get(&nd->root); 57831e6b01fSNick Piggin spin_unlock(&fs->lock); 57931e6b01fSNick Piggin } 58031e6b01fSNick Piggin 5818b61e74fSAl Viro rcu_read_unlock(); 58231e6b01fSNick Piggin return 0; 58319660af7SAl Viro 584e5c832d5SLinus Torvalds unlock_and_drop_dentry: 58531e6b01fSNick Piggin spin_unlock(&fs->lock); 586e5c832d5SLinus Torvalds drop_dentry: 5878b61e74fSAl Viro rcu_read_unlock(); 588e5c832d5SLinus Torvalds dput(dentry); 589d0d27277SLinus Torvalds goto drop_root_mnt; 590e5c832d5SLinus Torvalds out: 5918b61e74fSAl Viro rcu_read_unlock(); 592d0d27277SLinus Torvalds drop_root_mnt: 593d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 594d0d27277SLinus Torvalds nd->root.mnt = NULL; 59531e6b01fSNick Piggin return -ECHILD; 59631e6b01fSNick Piggin } 59731e6b01fSNick Piggin 5984ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 59934286d66SNick Piggin { 6004ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 60134286d66SNick Piggin } 60234286d66SNick Piggin 6039f1fafeeSAl Viro /** 6049f1fafeeSAl Viro * complete_walk - successful completion of path walk 6059f1fafeeSAl Viro * @nd: pointer nameidata 60639159de2SJeff Layton * 6079f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6089f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6099f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6109f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6119f1fafeeSAl Viro * need to drop nd->path. 61239159de2SJeff Layton */ 6139f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 61439159de2SJeff Layton { 61516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 61639159de2SJeff Layton int status; 61739159de2SJeff Layton 6189f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6199f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6209f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6219f1fafeeSAl Viro nd->root.mnt = NULL; 62215570086SLinus Torvalds 62348a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6248b61e74fSAl Viro rcu_read_unlock(); 62548a066e7SAl Viro return -ECHILD; 62648a066e7SAl Viro } 627e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6288b61e74fSAl Viro rcu_read_unlock(); 62948a066e7SAl Viro mntput(nd->path.mnt); 6309f1fafeeSAl Viro return -ECHILD; 6319f1fafeeSAl Viro } 632e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6338b61e74fSAl Viro rcu_read_unlock(); 634e5c832d5SLinus Torvalds dput(dentry); 63548a066e7SAl Viro mntput(nd->path.mnt); 636e5c832d5SLinus Torvalds return -ECHILD; 637e5c832d5SLinus Torvalds } 6388b61e74fSAl Viro rcu_read_unlock(); 6399f1fafeeSAl Viro } 6409f1fafeeSAl Viro 64116c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 64239159de2SJeff Layton return 0; 64339159de2SJeff Layton 644ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 64516c2cd71SAl Viro return 0; 64616c2cd71SAl Viro 647ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 64839159de2SJeff Layton if (status > 0) 64939159de2SJeff Layton return 0; 65039159de2SJeff Layton 65116c2cd71SAl Viro if (!status) 65239159de2SJeff Layton status = -ESTALE; 65316c2cd71SAl Viro 6549f1fafeeSAl Viro path_put(&nd->path); 65539159de2SJeff Layton return status; 65639159de2SJeff Layton } 65739159de2SJeff Layton 6582a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6592a737871SAl Viro { 660f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6612a737871SAl Viro } 6622a737871SAl Viro 6636de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6646de88d72SAl Viro 6657bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 66631e6b01fSNick Piggin { 66731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6687bd88377SAl Viro unsigned seq, res; 669c28cc364SNick Piggin 670c28cc364SNick Piggin do { 671c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 67231e6b01fSNick Piggin nd->root = fs->root; 6737bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 674c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6757bd88377SAl Viro return res; 67631e6b01fSNick Piggin } 67731e6b01fSNick Piggin 6781d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 679051d3812SIan Kent { 680051d3812SIan Kent dput(path->dentry); 6814ac91378SJan Blunck if (path->mnt != nd->path.mnt) 682051d3812SIan Kent mntput(path->mnt); 683051d3812SIan Kent } 684051d3812SIan Kent 6857b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6867b9337aaSNick Piggin struct nameidata *nd) 687051d3812SIan Kent { 68831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6894ac91378SJan Blunck dput(nd->path.dentry); 69031e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6914ac91378SJan Blunck mntput(nd->path.mnt); 6929a229683SHuang Shijie } 69331e6b01fSNick Piggin nd->path.mnt = path->mnt; 6944ac91378SJan Blunck nd->path.dentry = path->dentry; 695051d3812SIan Kent } 696051d3812SIan Kent 697b5fb63c1SChristoph Hellwig /* 698b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 699b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 700b5fb63c1SChristoph Hellwig */ 701b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 702b5fb63c1SChristoph Hellwig { 703b5fb63c1SChristoph Hellwig path_put(&nd->path); 704b5fb63c1SChristoph Hellwig 705b5fb63c1SChristoph Hellwig nd->path = *path; 706b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 707b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 708b5fb63c1SChristoph Hellwig } 709b5fb63c1SChristoph Hellwig 7101f55a6ecSAl Viro void nd_set_link(struct nameidata *nd, char *path) 7111f55a6ecSAl Viro { 7121f55a6ecSAl Viro nd->saved_names[nd->depth] = path; 7131f55a6ecSAl Viro } 7141f55a6ecSAl Viro EXPORT_SYMBOL(nd_set_link); 7151f55a6ecSAl Viro 7161f55a6ecSAl Viro char *nd_get_link(struct nameidata *nd) 7171f55a6ecSAl Viro { 7181f55a6ecSAl Viro return nd->saved_names[nd->depth]; 7191f55a6ecSAl Viro } 7201f55a6ecSAl Viro EXPORT_SYMBOL(nd_get_link); 7211f55a6ecSAl Viro 722574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 723574197e0SAl Viro { 724574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 7256d7b5aaeSAl Viro if (inode->i_op->put_link) 726574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 727574197e0SAl Viro path_put(link); 728574197e0SAl Viro } 729574197e0SAl Viro 730561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 731561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 732800179c9SKees Cook 733800179c9SKees Cook /** 734800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 735800179c9SKees Cook * @link: The path of the symlink 73655852635SRandy Dunlap * @nd: nameidata pathwalk data 737800179c9SKees Cook * 738800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 739800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 740800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 741800179c9SKees Cook * processes from failing races against path names that may change out 742800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 743800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 744800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 745800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 746800179c9SKees Cook * 747800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 748800179c9SKees Cook */ 749800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 750800179c9SKees Cook { 751800179c9SKees Cook const struct inode *inode; 752800179c9SKees Cook const struct inode *parent; 753800179c9SKees Cook 754800179c9SKees Cook if (!sysctl_protected_symlinks) 755800179c9SKees Cook return 0; 756800179c9SKees Cook 757800179c9SKees Cook /* Allowed if owner and follower match. */ 758800179c9SKees Cook inode = link->dentry->d_inode; 75981abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 760800179c9SKees Cook return 0; 761800179c9SKees Cook 762800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 763800179c9SKees Cook parent = nd->path.dentry->d_inode; 764800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 765800179c9SKees Cook return 0; 766800179c9SKees Cook 767800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 76881abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 769800179c9SKees Cook return 0; 770800179c9SKees Cook 771ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 772800179c9SKees Cook path_put_conditional(link, nd); 773800179c9SKees Cook path_put(&nd->path); 774800179c9SKees Cook return -EACCES; 775800179c9SKees Cook } 776800179c9SKees Cook 777800179c9SKees Cook /** 778800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 779800179c9SKees Cook * @inode: the source inode to hardlink from 780800179c9SKees Cook * 781800179c9SKees Cook * Return false if at least one of the following conditions: 782800179c9SKees Cook * - inode is not a regular file 783800179c9SKees Cook * - inode is setuid 784800179c9SKees Cook * - inode is setgid and group-exec 785800179c9SKees Cook * - access failure for read and write 786800179c9SKees Cook * 787800179c9SKees Cook * Otherwise returns true. 788800179c9SKees Cook */ 789800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 790800179c9SKees Cook { 791800179c9SKees Cook umode_t mode = inode->i_mode; 792800179c9SKees Cook 793800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 794800179c9SKees Cook if (!S_ISREG(mode)) 795800179c9SKees Cook return false; 796800179c9SKees Cook 797800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 798800179c9SKees Cook if (mode & S_ISUID) 799800179c9SKees Cook return false; 800800179c9SKees Cook 801800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 802800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 803800179c9SKees Cook return false; 804800179c9SKees Cook 805800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 806800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 807800179c9SKees Cook return false; 808800179c9SKees Cook 809800179c9SKees Cook return true; 810800179c9SKees Cook } 811800179c9SKees Cook 812800179c9SKees Cook /** 813800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 814800179c9SKees Cook * @link: the source to hardlink from 815800179c9SKees Cook * 816800179c9SKees Cook * Block hardlink when all of: 817800179c9SKees Cook * - sysctl_protected_hardlinks enabled 818800179c9SKees Cook * - fsuid does not match inode 819800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 820800179c9SKees Cook * - not CAP_FOWNER 821800179c9SKees Cook * 822800179c9SKees Cook * Returns 0 if successful, -ve on error. 823800179c9SKees Cook */ 824800179c9SKees Cook static int may_linkat(struct path *link) 825800179c9SKees Cook { 826800179c9SKees Cook const struct cred *cred; 827800179c9SKees Cook struct inode *inode; 828800179c9SKees Cook 829800179c9SKees Cook if (!sysctl_protected_hardlinks) 830800179c9SKees Cook return 0; 831800179c9SKees Cook 832800179c9SKees Cook cred = current_cred(); 833800179c9SKees Cook inode = link->dentry->d_inode; 834800179c9SKees Cook 835800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 836800179c9SKees Cook * otherwise, it must be a safe source. 837800179c9SKees Cook */ 83881abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 839800179c9SKees Cook capable(CAP_FOWNER)) 840800179c9SKees Cook return 0; 841800179c9SKees Cook 842a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 843800179c9SKees Cook return -EPERM; 844800179c9SKees Cook } 845800179c9SKees Cook 846def4af30SAl Viro static __always_inline int 847574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 8481da177e4SLinus Torvalds { 8497b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8506d7b5aaeSAl Viro int error; 8516d7b5aaeSAl Viro char *s; 8521da177e4SLinus Torvalds 853844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 854844a3917SAl Viro 8550e794589SAl Viro if (link->mnt == nd->path.mnt) 8560e794589SAl Viro mntget(link->mnt); 8570e794589SAl Viro 8586d7b5aaeSAl Viro error = -ELOOP; 8596d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8606d7b5aaeSAl Viro goto out_put_nd_path; 8616d7b5aaeSAl Viro 862574197e0SAl Viro cond_resched(); 863574197e0SAl Viro current->total_link_count++; 864574197e0SAl Viro 86568ac1234SAl Viro touch_atime(link); 8661da177e4SLinus Torvalds nd_set_link(nd, NULL); 867cd4e91d3SAl Viro 86836f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8696d7b5aaeSAl Viro if (error) 8706d7b5aaeSAl Viro goto out_put_nd_path; 87136f3b4f6SAl Viro 87286acdca1SAl Viro nd->last_type = LAST_BIND; 873def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 874def4af30SAl Viro error = PTR_ERR(*p); 8756d7b5aaeSAl Viro if (IS_ERR(*p)) 876408ef013SChristoph Hellwig goto out_put_nd_path; 8776d7b5aaeSAl Viro 878cc314eefSLinus Torvalds error = 0; 8796d7b5aaeSAl Viro s = nd_get_link(nd); 8806d7b5aaeSAl Viro if (s) { 881443ed254SAl Viro if (unlikely(IS_ERR(s))) { 882443ed254SAl Viro path_put(&nd->path); 883443ed254SAl Viro put_link(nd, link, *p); 884443ed254SAl Viro return PTR_ERR(s); 885443ed254SAl Viro } 886443ed254SAl Viro if (*s == '/') { 8877bd88377SAl Viro if (!nd->root.mnt) 888443ed254SAl Viro set_root(nd); 889443ed254SAl Viro path_put(&nd->path); 890443ed254SAl Viro nd->path = nd->root; 891443ed254SAl Viro path_get(&nd->root); 892443ed254SAl Viro nd->flags |= LOOKUP_JUMPED; 893443ed254SAl Viro } 894443ed254SAl Viro nd->inode = nd->path.dentry->d_inode; 895443ed254SAl Viro error = link_path_walk(s, nd); 8966d7b5aaeSAl Viro if (unlikely(error)) 8976d7b5aaeSAl Viro put_link(nd, link, *p); 898b5fb63c1SChristoph Hellwig } 8996d7b5aaeSAl Viro 9006d7b5aaeSAl Viro return error; 9016d7b5aaeSAl Viro 9026d7b5aaeSAl Viro out_put_nd_path: 90398f6ef64SArnd Bergmann *p = NULL; 9046d7b5aaeSAl Viro path_put(&nd->path); 9056d7b5aaeSAl Viro path_put(link); 9061da177e4SLinus Torvalds return error; 9071da177e4SLinus Torvalds } 9081da177e4SLinus Torvalds 90931e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 91031e6b01fSNick Piggin { 9110714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9120714a533SAl Viro struct mount *parent; 91331e6b01fSNick Piggin struct dentry *mountpoint; 91431e6b01fSNick Piggin 9150714a533SAl Viro parent = mnt->mnt_parent; 9160714a533SAl Viro if (&parent->mnt == path->mnt) 91731e6b01fSNick Piggin return 0; 918a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 91931e6b01fSNick Piggin path->dentry = mountpoint; 9200714a533SAl Viro path->mnt = &parent->mnt; 92131e6b01fSNick Piggin return 1; 92231e6b01fSNick Piggin } 92331e6b01fSNick Piggin 924f015f126SDavid Howells /* 925f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 926f015f126SDavid Howells * 927f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 928f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 929f015f126SDavid Howells * Up is towards /. 930f015f126SDavid Howells * 931f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 932f015f126SDavid Howells * root. 933f015f126SDavid Howells */ 934bab77ebfSAl Viro int follow_up(struct path *path) 9351da177e4SLinus Torvalds { 9360714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9370714a533SAl Viro struct mount *parent; 9381da177e4SLinus Torvalds struct dentry *mountpoint; 93999b7db7bSNick Piggin 94048a066e7SAl Viro read_seqlock_excl(&mount_lock); 9410714a533SAl Viro parent = mnt->mnt_parent; 9423c0a6163SAl Viro if (parent == mnt) { 94348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9441da177e4SLinus Torvalds return 0; 9451da177e4SLinus Torvalds } 9460714a533SAl Viro mntget(&parent->mnt); 947a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 94848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 949bab77ebfSAl Viro dput(path->dentry); 950bab77ebfSAl Viro path->dentry = mountpoint; 951bab77ebfSAl Viro mntput(path->mnt); 9520714a533SAl Viro path->mnt = &parent->mnt; 9531da177e4SLinus Torvalds return 1; 9541da177e4SLinus Torvalds } 9554d359507SAl Viro EXPORT_SYMBOL(follow_up); 9561da177e4SLinus Torvalds 957b5c84bf6SNick Piggin /* 9589875cf80SDavid Howells * Perform an automount 9599875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9609875cf80SDavid Howells * were called with. 9611da177e4SLinus Torvalds */ 9629875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9639875cf80SDavid Howells bool *need_mntput) 96431e6b01fSNick Piggin { 9659875cf80SDavid Howells struct vfsmount *mnt; 966ea5b778aSDavid Howells int err; 9679875cf80SDavid Howells 9689875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9699875cf80SDavid Howells return -EREMOTE; 9709875cf80SDavid Howells 9710ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9720ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9730ec26fd0SMiklos Szeredi * the name. 9740ec26fd0SMiklos Szeredi * 9750ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9765a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9770ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9780ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9790ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9800ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9815a30d8a2SDavid Howells */ 9825a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 983d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9845a30d8a2SDavid Howells path->dentry->d_inode) 9859875cf80SDavid Howells return -EISDIR; 9860ec26fd0SMiklos Szeredi 9879875cf80SDavid Howells current->total_link_count++; 9889875cf80SDavid Howells if (current->total_link_count >= 40) 9899875cf80SDavid Howells return -ELOOP; 9909875cf80SDavid Howells 9919875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9929875cf80SDavid Howells if (IS_ERR(mnt)) { 9939875cf80SDavid Howells /* 9949875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9959875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9969875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9979875cf80SDavid Howells * 9989875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9999875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10009875cf80SDavid Howells * the path is inaccessible and we should say so. 10019875cf80SDavid Howells */ 100249084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 10039875cf80SDavid Howells return -EREMOTE; 10049875cf80SDavid Howells return PTR_ERR(mnt); 100531e6b01fSNick Piggin } 1006ea5b778aSDavid Howells 10079875cf80SDavid Howells if (!mnt) /* mount collision */ 10089875cf80SDavid Howells return 0; 10099875cf80SDavid Howells 10108aef1884SAl Viro if (!*need_mntput) { 10118aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10128aef1884SAl Viro mntget(path->mnt); 10138aef1884SAl Viro *need_mntput = true; 10148aef1884SAl Viro } 101519a167afSAl Viro err = finish_automount(mnt, path); 1016ea5b778aSDavid Howells 1017ea5b778aSDavid Howells switch (err) { 1018ea5b778aSDavid Howells case -EBUSY: 1019ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 102019a167afSAl Viro return 0; 1021ea5b778aSDavid Howells case 0: 10228aef1884SAl Viro path_put(path); 10239875cf80SDavid Howells path->mnt = mnt; 10249875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10259875cf80SDavid Howells return 0; 102619a167afSAl Viro default: 102719a167afSAl Viro return err; 10289875cf80SDavid Howells } 102919a167afSAl Viro 1030ea5b778aSDavid Howells } 10319875cf80SDavid Howells 10329875cf80SDavid Howells /* 10339875cf80SDavid Howells * Handle a dentry that is managed in some way. 1034cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10359875cf80SDavid Howells * - Flagged as mountpoint 10369875cf80SDavid Howells * - Flagged as automount point 10379875cf80SDavid Howells * 10389875cf80SDavid Howells * This may only be called in refwalk mode. 10399875cf80SDavid Howells * 10409875cf80SDavid Howells * Serialization is taken care of in namespace.c 10419875cf80SDavid Howells */ 10429875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10439875cf80SDavid Howells { 10448aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10459875cf80SDavid Howells unsigned managed; 10469875cf80SDavid Howells bool need_mntput = false; 10478aef1884SAl Viro int ret = 0; 10489875cf80SDavid Howells 10499875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10509875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10519875cf80SDavid Howells * the components of that value change under us */ 10529875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10539875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10549875cf80SDavid Howells unlikely(managed != 0)) { 1055cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1056cc53ce53SDavid Howells * being held. */ 1057cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1058cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1059cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10601aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1061cc53ce53SDavid Howells if (ret < 0) 10628aef1884SAl Viro break; 1063cc53ce53SDavid Howells } 1064cc53ce53SDavid Howells 10659875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10669875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10679875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10689875cf80SDavid Howells if (mounted) { 10699875cf80SDavid Howells dput(path->dentry); 10709875cf80SDavid Howells if (need_mntput) 1071463ffb2eSAl Viro mntput(path->mnt); 1072463ffb2eSAl Viro path->mnt = mounted; 1073463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10749875cf80SDavid Howells need_mntput = true; 10759875cf80SDavid Howells continue; 1076463ffb2eSAl Viro } 1077463ffb2eSAl Viro 10789875cf80SDavid Howells /* Something is mounted on this dentry in another 10799875cf80SDavid Howells * namespace and/or whatever was mounted there in this 108048a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 108148a066e7SAl Viro * get it */ 10821da177e4SLinus Torvalds } 10839875cf80SDavid Howells 10849875cf80SDavid Howells /* Handle an automount point */ 10859875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10869875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10879875cf80SDavid Howells if (ret < 0) 10888aef1884SAl Viro break; 10899875cf80SDavid Howells continue; 10909875cf80SDavid Howells } 10919875cf80SDavid Howells 10929875cf80SDavid Howells /* We didn't change the current path point */ 10939875cf80SDavid Howells break; 10949875cf80SDavid Howells } 10958aef1884SAl Viro 10968aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10978aef1884SAl Viro mntput(path->mnt); 10988aef1884SAl Viro if (ret == -EISDIR) 10998aef1884SAl Viro ret = 0; 1100a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 11011da177e4SLinus Torvalds } 11021da177e4SLinus Torvalds 1103cc53ce53SDavid Howells int follow_down_one(struct path *path) 11041da177e4SLinus Torvalds { 11051da177e4SLinus Torvalds struct vfsmount *mounted; 11061da177e4SLinus Torvalds 11071c755af4SAl Viro mounted = lookup_mnt(path); 11081da177e4SLinus Torvalds if (mounted) { 11099393bd07SAl Viro dput(path->dentry); 11109393bd07SAl Viro mntput(path->mnt); 11119393bd07SAl Viro path->mnt = mounted; 11129393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11131da177e4SLinus Torvalds return 1; 11141da177e4SLinus Torvalds } 11151da177e4SLinus Torvalds return 0; 11161da177e4SLinus Torvalds } 11174d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11181da177e4SLinus Torvalds 1119b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 112062a7375eSIan Kent { 1121b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1122b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 112362a7375eSIan Kent } 112462a7375eSIan Kent 11259875cf80SDavid Howells /* 1126287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1127287548e4SAl Viro * we meet a managed dentry that would need blocking. 11289875cf80SDavid Howells */ 11299875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1130287548e4SAl Viro struct inode **inode) 11319875cf80SDavid Howells { 113262a7375eSIan Kent for (;;) { 1133c7105365SAl Viro struct mount *mounted; 113462a7375eSIan Kent /* 113562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 113662a7375eSIan Kent * that wants to block transit. 113762a7375eSIan Kent */ 1138b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1139b8faf035SNeilBrown case -ECHILD: 1140b8faf035SNeilBrown default: 1141ab90911fSDavid Howells return false; 1142b8faf035SNeilBrown case -EISDIR: 1143b8faf035SNeilBrown return true; 1144b8faf035SNeilBrown case 0: 1145b8faf035SNeilBrown break; 1146b8faf035SNeilBrown } 114762a7375eSIan Kent 114862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1149b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 115062a7375eSIan Kent 1151474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11529875cf80SDavid Howells if (!mounted) 11539875cf80SDavid Howells break; 1154c7105365SAl Viro path->mnt = &mounted->mnt; 1155c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1156a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11579875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 115859430262SLinus Torvalds /* 115959430262SLinus Torvalds * Update the inode too. We don't need to re-check the 116059430262SLinus Torvalds * dentry sequence number here after this d_inode read, 116159430262SLinus Torvalds * because a mount-point is always pinned. 116259430262SLinus Torvalds */ 116359430262SLinus Torvalds *inode = path->dentry->d_inode; 11649875cf80SDavid Howells } 1165f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1166b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1167287548e4SAl Viro } 1168287548e4SAl Viro 116931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 117031e6b01fSNick Piggin { 11714023bfc9SAl Viro struct inode *inode = nd->inode; 11727bd88377SAl Viro if (!nd->root.mnt) 117331e6b01fSNick Piggin set_root_rcu(nd); 117431e6b01fSNick Piggin 117531e6b01fSNick Piggin while (1) { 117631e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 117731e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 117831e6b01fSNick Piggin break; 117931e6b01fSNick Piggin } 118031e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 118131e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 118231e6b01fSNick Piggin struct dentry *parent = old->d_parent; 118331e6b01fSNick Piggin unsigned seq; 118431e6b01fSNick Piggin 11854023bfc9SAl Viro inode = parent->d_inode; 118631e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 118731e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1188ef7562d5SAl Viro goto failed; 118931e6b01fSNick Piggin nd->path.dentry = parent; 119031e6b01fSNick Piggin nd->seq = seq; 119131e6b01fSNick Piggin break; 119231e6b01fSNick Piggin } 119331e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 119431e6b01fSNick Piggin break; 11954023bfc9SAl Viro inode = nd->path.dentry->d_inode; 119631e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 119731e6b01fSNick Piggin } 1198b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1199b37199e6SAl Viro struct mount *mounted; 1200b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1201b37199e6SAl Viro if (!mounted) 1202b37199e6SAl Viro break; 1203b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1204b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12054023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1206b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1207f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1208b37199e6SAl Viro goto failed; 1209b37199e6SAl Viro } 12104023bfc9SAl Viro nd->inode = inode; 121131e6b01fSNick Piggin return 0; 1212ef7562d5SAl Viro 1213ef7562d5SAl Viro failed: 1214ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 12155b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1216ef7562d5SAl Viro nd->root.mnt = NULL; 12178b61e74fSAl Viro rcu_read_unlock(); 1218ef7562d5SAl Viro return -ECHILD; 121931e6b01fSNick Piggin } 122031e6b01fSNick Piggin 12219875cf80SDavid Howells /* 1222cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1223cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1224cc53ce53SDavid Howells * caller is permitted to proceed or not. 1225cc53ce53SDavid Howells */ 12267cc90cc3SAl Viro int follow_down(struct path *path) 1227cc53ce53SDavid Howells { 1228cc53ce53SDavid Howells unsigned managed; 1229cc53ce53SDavid Howells int ret; 1230cc53ce53SDavid Howells 1231cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1232cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1233cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1234cc53ce53SDavid Howells * being held. 1235cc53ce53SDavid Howells * 1236cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1237cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1238cc53ce53SDavid Howells * other than its daemon the right to mount on its 1239cc53ce53SDavid Howells * superstructure. 1240cc53ce53SDavid Howells * 1241cc53ce53SDavid Howells * The filesystem may sleep at this point. 1242cc53ce53SDavid Howells */ 1243cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1244cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1245cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1246ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12471aed3e42SAl Viro path->dentry, false); 1248cc53ce53SDavid Howells if (ret < 0) 1249cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1250cc53ce53SDavid Howells } 1251cc53ce53SDavid Howells 1252cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1253cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1254cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1255cc53ce53SDavid Howells if (!mounted) 1256cc53ce53SDavid Howells break; 1257cc53ce53SDavid Howells dput(path->dentry); 1258cc53ce53SDavid Howells mntput(path->mnt); 1259cc53ce53SDavid Howells path->mnt = mounted; 1260cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1261cc53ce53SDavid Howells continue; 1262cc53ce53SDavid Howells } 1263cc53ce53SDavid Howells 1264cc53ce53SDavid Howells /* Don't handle automount points here */ 1265cc53ce53SDavid Howells break; 1266cc53ce53SDavid Howells } 1267cc53ce53SDavid Howells return 0; 1268cc53ce53SDavid Howells } 12694d359507SAl Viro EXPORT_SYMBOL(follow_down); 1270cc53ce53SDavid Howells 1271cc53ce53SDavid Howells /* 12729875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12739875cf80SDavid Howells */ 12749875cf80SDavid Howells static void follow_mount(struct path *path) 12759875cf80SDavid Howells { 12769875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12779875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12789875cf80SDavid Howells if (!mounted) 12799875cf80SDavid Howells break; 12809875cf80SDavid Howells dput(path->dentry); 12819875cf80SDavid Howells mntput(path->mnt); 12829875cf80SDavid Howells path->mnt = mounted; 12839875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12849875cf80SDavid Howells } 12859875cf80SDavid Howells } 12869875cf80SDavid Howells 128731e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12881da177e4SLinus Torvalds { 12897bd88377SAl Viro if (!nd->root.mnt) 12902a737871SAl Viro set_root(nd); 1291e518ddb7SAndreas Mohr 12921da177e4SLinus Torvalds while(1) { 12934ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12941da177e4SLinus Torvalds 12952a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12962a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12971da177e4SLinus Torvalds break; 12981da177e4SLinus Torvalds } 12994ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13003088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13013088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13021da177e4SLinus Torvalds dput(old); 13031da177e4SLinus Torvalds break; 13041da177e4SLinus Torvalds } 13053088dd70SAl Viro if (!follow_up(&nd->path)) 13061da177e4SLinus Torvalds break; 13071da177e4SLinus Torvalds } 130879ed0226SAl Viro follow_mount(&nd->path); 130931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13101da177e4SLinus Torvalds } 13111da177e4SLinus Torvalds 13121da177e4SLinus Torvalds /* 1313bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1314bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1315bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1316bad61189SMiklos Szeredi * 1317bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1318baa03890SNick Piggin */ 1319bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1320201f956eSAl Viro unsigned int flags, bool *need_lookup) 1321baa03890SNick Piggin { 1322baa03890SNick Piggin struct dentry *dentry; 1323bad61189SMiklos Szeredi int error; 1324baa03890SNick Piggin 1325bad61189SMiklos Szeredi *need_lookup = false; 1326bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1327bad61189SMiklos Szeredi if (dentry) { 132839e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1329201f956eSAl Viro error = d_revalidate(dentry, flags); 1330bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1331bad61189SMiklos Szeredi if (error < 0) { 1332bad61189SMiklos Szeredi dput(dentry); 1333bad61189SMiklos Szeredi return ERR_PTR(error); 13345542aa2fSEric W. Biederman } else { 13355542aa2fSEric W. Biederman d_invalidate(dentry); 1336bad61189SMiklos Szeredi dput(dentry); 1337bad61189SMiklos Szeredi dentry = NULL; 1338bad61189SMiklos Szeredi } 1339bad61189SMiklos Szeredi } 1340bad61189SMiklos Szeredi } 1341bad61189SMiklos Szeredi } 1342baa03890SNick Piggin 1343bad61189SMiklos Szeredi if (!dentry) { 1344bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1345baa03890SNick Piggin if (unlikely(!dentry)) 1346baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1347baa03890SNick Piggin 1348bad61189SMiklos Szeredi *need_lookup = true; 1349baa03890SNick Piggin } 1350baa03890SNick Piggin return dentry; 1351baa03890SNick Piggin } 1352baa03890SNick Piggin 1353baa03890SNick Piggin /* 135413a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 135513a2c3beSJ. Bruce Fields * unhashed. 1356bad61189SMiklos Szeredi * 1357bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 135844396f4bSJosef Bacik */ 1359bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 136072bd866aSAl Viro unsigned int flags) 136144396f4bSJosef Bacik { 136244396f4bSJosef Bacik struct dentry *old; 136344396f4bSJosef Bacik 136444396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1365bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1366e188dc02SMiklos Szeredi dput(dentry); 136744396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1368e188dc02SMiklos Szeredi } 136944396f4bSJosef Bacik 137072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 137144396f4bSJosef Bacik if (unlikely(old)) { 137244396f4bSJosef Bacik dput(dentry); 137344396f4bSJosef Bacik dentry = old; 137444396f4bSJosef Bacik } 137544396f4bSJosef Bacik return dentry; 137644396f4bSJosef Bacik } 137744396f4bSJosef Bacik 1378a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 137972bd866aSAl Viro struct dentry *base, unsigned int flags) 1380a3255546SAl Viro { 1381bad61189SMiklos Szeredi bool need_lookup; 1382a3255546SAl Viro struct dentry *dentry; 1383a3255546SAl Viro 138472bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1385bad61189SMiklos Szeredi if (!need_lookup) 1386a3255546SAl Viro return dentry; 1387bad61189SMiklos Szeredi 138872bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1389a3255546SAl Viro } 1390a3255546SAl Viro 139144396f4bSJosef Bacik /* 13921da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13931da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13941da177e4SLinus Torvalds * It _is_ time-critical. 13951da177e4SLinus Torvalds */ 1396e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 139731e6b01fSNick Piggin struct path *path, struct inode **inode) 13981da177e4SLinus Torvalds { 13994ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 140031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14015a18fff2SAl Viro int need_reval = 1; 14025a18fff2SAl Viro int status = 1; 14039875cf80SDavid Howells int err; 14049875cf80SDavid Howells 14053cac260aSAl Viro /* 1406b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1407b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1408b04f784eSNick Piggin * do the non-racy lookup, below. 1409b04f784eSNick Piggin */ 141031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 141131e6b01fSNick Piggin unsigned seq; 1412da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14135a18fff2SAl Viro if (!dentry) 14145a18fff2SAl Viro goto unlazy; 14155a18fff2SAl Viro 141612f8ad4bSLinus Torvalds /* 141712f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 141812f8ad4bSLinus Torvalds * the dentry name information from lookup. 141912f8ad4bSLinus Torvalds */ 142012f8ad4bSLinus Torvalds *inode = dentry->d_inode; 142112f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 142212f8ad4bSLinus Torvalds return -ECHILD; 142312f8ad4bSLinus Torvalds 142412f8ad4bSLinus Torvalds /* 142512f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 142612f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 142712f8ad4bSLinus Torvalds * 142812f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 142912f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 143012f8ad4bSLinus Torvalds */ 143131e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 143231e6b01fSNick Piggin return -ECHILD; 143331e6b01fSNick Piggin nd->seq = seq; 14345a18fff2SAl Viro 143524643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14364ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14375a18fff2SAl Viro if (unlikely(status <= 0)) { 14385a18fff2SAl Viro if (status != -ECHILD) 14395a18fff2SAl Viro need_reval = 0; 14405a18fff2SAl Viro goto unlazy; 14415a18fff2SAl Viro } 144224643087SAl Viro } 144331e6b01fSNick Piggin path->mnt = mnt; 144431e6b01fSNick Piggin path->dentry = dentry; 1445b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14469875cf80SDavid Howells return 0; 14475a18fff2SAl Viro unlazy: 144819660af7SAl Viro if (unlazy_walk(nd, dentry)) 14495a18fff2SAl Viro return -ECHILD; 14505a18fff2SAl Viro } else { 1451e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 145224643087SAl Viro } 14535a18fff2SAl Viro 145481e6f520SAl Viro if (unlikely(!dentry)) 145581e6f520SAl Viro goto need_lookup; 14565a18fff2SAl Viro 14575a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14584ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14595a18fff2SAl Viro if (unlikely(status <= 0)) { 14605a18fff2SAl Viro if (status < 0) { 14615a18fff2SAl Viro dput(dentry); 14625a18fff2SAl Viro return status; 14635a18fff2SAl Viro } 14645542aa2fSEric W. Biederman d_invalidate(dentry); 14655a18fff2SAl Viro dput(dentry); 146681e6f520SAl Viro goto need_lookup; 14675a18fff2SAl Viro } 1468697f514dSMiklos Szeredi 14691da177e4SLinus Torvalds path->mnt = mnt; 14701da177e4SLinus Torvalds path->dentry = dentry; 14719875cf80SDavid Howells err = follow_managed(path, nd->flags); 147289312214SIan Kent if (unlikely(err < 0)) { 147389312214SIan Kent path_put_conditional(path, nd); 14749875cf80SDavid Howells return err; 147589312214SIan Kent } 1476a3fbbde7SAl Viro if (err) 1477a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 147831e6b01fSNick Piggin *inode = path->dentry->d_inode; 14791da177e4SLinus Torvalds return 0; 148081e6f520SAl Viro 148181e6f520SAl Viro need_lookup: 1482697f514dSMiklos Szeredi return 1; 1483697f514dSMiklos Szeredi } 1484697f514dSMiklos Szeredi 1485697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1486cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1487697f514dSMiklos Szeredi { 1488697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1489697f514dSMiklos Szeredi int err; 1490697f514dSMiklos Szeredi 1491697f514dSMiklos Szeredi parent = nd->path.dentry; 149281e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 149381e6f520SAl Viro 149481e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1495cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 149681e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 149781e6f520SAl Viro if (IS_ERR(dentry)) 149881e6f520SAl Viro return PTR_ERR(dentry); 1499697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1500697f514dSMiklos Szeredi path->dentry = dentry; 1501697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1502697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1503697f514dSMiklos Szeredi path_put_conditional(path, nd); 1504697f514dSMiklos Szeredi return err; 1505697f514dSMiklos Szeredi } 1506697f514dSMiklos Szeredi if (err) 1507697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1508697f514dSMiklos Szeredi return 0; 15091da177e4SLinus Torvalds } 15101da177e4SLinus Torvalds 151152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 151252094c8aSAl Viro { 151352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15144ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 151552094c8aSAl Viro if (err != -ECHILD) 151652094c8aSAl Viro return err; 151719660af7SAl Viro if (unlazy_walk(nd, NULL)) 151852094c8aSAl Viro return -ECHILD; 151952094c8aSAl Viro } 15204ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152152094c8aSAl Viro } 152252094c8aSAl Viro 15239856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15249856fa1bSAl Viro { 15259856fa1bSAl Viro if (type == LAST_DOTDOT) { 15269856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15279856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15289856fa1bSAl Viro return -ECHILD; 15299856fa1bSAl Viro } else 15309856fa1bSAl Viro follow_dotdot(nd); 15319856fa1bSAl Viro } 15329856fa1bSAl Viro return 0; 15339856fa1bSAl Viro } 15349856fa1bSAl Viro 1535951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1536951361f9SAl Viro { 1537951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1538951361f9SAl Viro path_put(&nd->path); 1539951361f9SAl Viro } else { 1540951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15415b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1542951361f9SAl Viro nd->root.mnt = NULL; 15438b61e74fSAl Viro rcu_read_unlock(); 1544951361f9SAl Viro } 1545951361f9SAl Viro } 1546951361f9SAl Viro 15473ddcd056SLinus Torvalds /* 15483ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15493ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15503ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15513ddcd056SLinus Torvalds * for the common case. 15523ddcd056SLinus Torvalds */ 1553b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15543ddcd056SLinus Torvalds { 1555b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15563ddcd056SLinus Torvalds } 15573ddcd056SLinus Torvalds 1558ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 155921b9b073SAl Viro int follow) 1560ce57dfc1SAl Viro { 1561ce57dfc1SAl Viro struct inode *inode; 1562ce57dfc1SAl Viro int err; 1563ce57dfc1SAl Viro /* 1564ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1565ce57dfc1SAl Viro * to be able to know about the current root directory and 1566ce57dfc1SAl Viro * parent relationships. 1567ce57dfc1SAl Viro */ 156821b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 156921b9b073SAl Viro return handle_dots(nd, nd->last_type); 1570e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1571ce57dfc1SAl Viro if (unlikely(err)) { 1572697f514dSMiklos Szeredi if (err < 0) 1573697f514dSMiklos Szeredi goto out_err; 1574697f514dSMiklos Szeredi 1575cc2a5271SAl Viro err = lookup_slow(nd, path); 1576697f514dSMiklos Szeredi if (err < 0) 1577697f514dSMiklos Szeredi goto out_err; 1578697f514dSMiklos Szeredi 1579697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1580ce57dfc1SAl Viro } 1581697f514dSMiklos Szeredi err = -ENOENT; 158222213318SAl Viro if (!inode || d_is_negative(path->dentry)) 1583697f514dSMiklos Szeredi goto out_path_put; 1584697f514dSMiklos Szeredi 1585b18825a7SDavid Howells if (should_follow_link(path->dentry, follow)) { 158619660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 158719660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1588697f514dSMiklos Szeredi err = -ECHILD; 1589697f514dSMiklos Szeredi goto out_err; 159019660af7SAl Viro } 159119660af7SAl Viro } 1592ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1593ce57dfc1SAl Viro return 1; 1594ce57dfc1SAl Viro } 1595ce57dfc1SAl Viro path_to_nameidata(path, nd); 1596ce57dfc1SAl Viro nd->inode = inode; 1597ce57dfc1SAl Viro return 0; 1598697f514dSMiklos Szeredi 1599697f514dSMiklos Szeredi out_path_put: 1600697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1601697f514dSMiklos Szeredi out_err: 1602697f514dSMiklos Szeredi terminate_walk(nd); 1603697f514dSMiklos Szeredi return err; 1604ce57dfc1SAl Viro } 1605ce57dfc1SAl Viro 16061da177e4SLinus Torvalds /* 1607b356379aSAl Viro * This limits recursive symlink follows to 8, while 1608b356379aSAl Viro * limiting consecutive symlinks to 40. 1609b356379aSAl Viro * 1610b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1611b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1612b356379aSAl Viro */ 1613b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1614b356379aSAl Viro { 1615b356379aSAl Viro int res; 1616b356379aSAl Viro 1617b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1618b356379aSAl Viro path_put_conditional(path, nd); 1619b356379aSAl Viro path_put(&nd->path); 1620b356379aSAl Viro return -ELOOP; 1621b356379aSAl Viro } 16221a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1623b356379aSAl Viro 1624b356379aSAl Viro nd->depth++; 1625b356379aSAl Viro current->link_count++; 1626b356379aSAl Viro 1627b356379aSAl Viro do { 1628b356379aSAl Viro struct path link = *path; 1629b356379aSAl Viro void *cookie; 1630574197e0SAl Viro 1631574197e0SAl Viro res = follow_link(&link, nd, &cookie); 16326d7b5aaeSAl Viro if (res) 16336d7b5aaeSAl Viro break; 163421b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1635574197e0SAl Viro put_link(nd, &link, cookie); 1636b356379aSAl Viro } while (res > 0); 1637b356379aSAl Viro 1638b356379aSAl Viro current->link_count--; 1639b356379aSAl Viro nd->depth--; 1640b356379aSAl Viro return res; 1641b356379aSAl Viro } 1642b356379aSAl Viro 1643b356379aSAl Viro /* 1644bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1645bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1646bfcfaa77SLinus Torvalds * 1647bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1648bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1649bfcfaa77SLinus Torvalds * fast. 1650bfcfaa77SLinus Torvalds * 1651bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1652bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1653bfcfaa77SLinus Torvalds * crossing operation. 1654bfcfaa77SLinus Torvalds * 1655bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1656bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1657bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1658bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1659bfcfaa77SLinus Torvalds */ 1660bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1661bfcfaa77SLinus Torvalds 1662f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1663bfcfaa77SLinus Torvalds 1664f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1665bfcfaa77SLinus Torvalds 1666bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1667bfcfaa77SLinus Torvalds { 166899d263d4SLinus Torvalds return hash_64(hash, 32); 1669bfcfaa77SLinus Torvalds } 1670bfcfaa77SLinus Torvalds 1671bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1674bfcfaa77SLinus Torvalds 1675bfcfaa77SLinus Torvalds #endif 1676bfcfaa77SLinus Torvalds 1677bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1678bfcfaa77SLinus Torvalds { 1679bfcfaa77SLinus Torvalds unsigned long a, mask; 1680bfcfaa77SLinus Torvalds unsigned long hash = 0; 1681bfcfaa77SLinus Torvalds 1682bfcfaa77SLinus Torvalds for (;;) { 1683e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1684bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1685bfcfaa77SLinus Torvalds break; 1686bfcfaa77SLinus Torvalds hash += a; 1687f132c5beSAl Viro hash *= 9; 1688bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1689bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1690bfcfaa77SLinus Torvalds if (!len) 1691bfcfaa77SLinus Torvalds goto done; 1692bfcfaa77SLinus Torvalds } 1693a5c21dceSWill Deacon mask = bytemask_from_count(len); 1694bfcfaa77SLinus Torvalds hash += mask & a; 1695bfcfaa77SLinus Torvalds done: 1696bfcfaa77SLinus Torvalds return fold_hash(hash); 1697bfcfaa77SLinus Torvalds } 1698bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1699bfcfaa77SLinus Torvalds 1700bfcfaa77SLinus Torvalds /* 1701bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1702d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1703bfcfaa77SLinus Torvalds */ 1704d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1705bfcfaa77SLinus Torvalds { 170636126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 170736126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1708bfcfaa77SLinus Torvalds 1709bfcfaa77SLinus Torvalds hash = a = 0; 1710bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1711bfcfaa77SLinus Torvalds do { 1712bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1713bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1714e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 171536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 171636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1717bfcfaa77SLinus Torvalds 171836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 171936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172036126f8fSLinus Torvalds 172136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 172236126f8fSLinus Torvalds 172336126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17249226b5b4SLinus Torvalds len += find_zero(mask); 1725d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1726bfcfaa77SLinus Torvalds } 1727bfcfaa77SLinus Torvalds 1728bfcfaa77SLinus Torvalds #else 1729bfcfaa77SLinus Torvalds 17300145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17310145acc2SLinus Torvalds { 17320145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17330145acc2SLinus Torvalds while (len--) 17340145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17350145acc2SLinus Torvalds return end_name_hash(hash); 17360145acc2SLinus Torvalds } 1737ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17380145acc2SLinus Torvalds 17393ddcd056SLinus Torvalds /* 1740200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1741200e9ef7SLinus Torvalds * one character. 1742200e9ef7SLinus Torvalds */ 1743d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1744200e9ef7SLinus Torvalds { 1745200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1746200e9ef7SLinus Torvalds unsigned long len = 0, c; 1747200e9ef7SLinus Torvalds 1748200e9ef7SLinus Torvalds c = (unsigned char)*name; 1749200e9ef7SLinus Torvalds do { 1750200e9ef7SLinus Torvalds len++; 1751200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1752200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1753200e9ef7SLinus Torvalds } while (c && c != '/'); 1754d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1755200e9ef7SLinus Torvalds } 1756200e9ef7SLinus Torvalds 1757bfcfaa77SLinus Torvalds #endif 1758bfcfaa77SLinus Torvalds 1759200e9ef7SLinus Torvalds /* 17601da177e4SLinus Torvalds * Name resolution. 1761ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1762ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17631da177e4SLinus Torvalds * 1764ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1765ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17661da177e4SLinus Torvalds */ 17676de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17681da177e4SLinus Torvalds { 17691da177e4SLinus Torvalds struct path next; 17701da177e4SLinus Torvalds int err; 17711da177e4SLinus Torvalds 17721da177e4SLinus Torvalds while (*name=='/') 17731da177e4SLinus Torvalds name++; 17741da177e4SLinus Torvalds if (!*name) 1775086e183aSAl Viro return 0; 17761da177e4SLinus Torvalds 17771da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17781da177e4SLinus Torvalds for(;;) { 1779d6bb3e90SLinus Torvalds u64 hash_len; 1780fe479a58SAl Viro int type; 17811da177e4SLinus Torvalds 178252094c8aSAl Viro err = may_lookup(nd); 17831da177e4SLinus Torvalds if (err) 17841da177e4SLinus Torvalds break; 17851da177e4SLinus Torvalds 1786d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17871da177e4SLinus Torvalds 1788fe479a58SAl Viro type = LAST_NORM; 1789d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1790fe479a58SAl Viro case 2: 1791200e9ef7SLinus Torvalds if (name[1] == '.') { 1792fe479a58SAl Viro type = LAST_DOTDOT; 179316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 179416c2cd71SAl Viro } 1795fe479a58SAl Viro break; 1796fe479a58SAl Viro case 1: 1797fe479a58SAl Viro type = LAST_DOT; 1798fe479a58SAl Viro } 17995a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18005a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18025a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1803a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1804da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18055a202bcdSAl Viro if (err < 0) 18065a202bcdSAl Viro break; 1807d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1808d6bb3e90SLinus Torvalds name = this.name; 18095a202bcdSAl Viro } 18105a202bcdSAl Viro } 1811fe479a58SAl Viro 1812d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1813d6bb3e90SLinus Torvalds nd->last.name = name; 18145f4a6a69SAl Viro nd->last_type = type; 18155f4a6a69SAl Viro 1816d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1817d6bb3e90SLinus Torvalds if (!*name) 18185f4a6a69SAl Viro return 0; 1819200e9ef7SLinus Torvalds /* 1820200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1821200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1822200e9ef7SLinus Torvalds */ 1823200e9ef7SLinus Torvalds do { 1824d6bb3e90SLinus Torvalds name++; 1825d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1826d6bb3e90SLinus Torvalds if (!*name) 18275f4a6a69SAl Viro return 0; 18285f4a6a69SAl Viro 182921b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1830ce57dfc1SAl Viro if (err < 0) 1831ce57dfc1SAl Viro return err; 1832fe479a58SAl Viro 1833ce57dfc1SAl Viro if (err) { 1834b356379aSAl Viro err = nested_symlink(&next, nd); 18351da177e4SLinus Torvalds if (err) 1836a7472babSAl Viro return err; 183731e6b01fSNick Piggin } 183844b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18393ddcd056SLinus Torvalds err = -ENOTDIR; 18403ddcd056SLinus Torvalds break; 18415f4a6a69SAl Viro } 1842ce57dfc1SAl Viro } 1843951361f9SAl Viro terminate_walk(nd); 18441da177e4SLinus Torvalds return err; 18451da177e4SLinus Torvalds } 18461da177e4SLinus Torvalds 184770e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 184870e9b357SAl Viro struct nameidata *nd, struct file **fp) 184931e6b01fSNick Piggin { 185031e6b01fSNick Piggin int retval = 0; 185131e6b01fSNick Piggin 185231e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 185316c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 185431e6b01fSNick Piggin nd->depth = 0; 18555b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1856b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1857b18825a7SDavid Howells struct inode *inode = root->d_inode; 185873d049a4SAl Viro if (*name) { 185944b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18605b6ca027SAl Viro return -ENOTDIR; 18615b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18625b6ca027SAl Viro if (retval) 18635b6ca027SAl Viro return retval; 186473d049a4SAl Viro } 18655b6ca027SAl Viro nd->path = nd->root; 18665b6ca027SAl Viro nd->inode = inode; 18675b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18688b61e74fSAl Viro rcu_read_lock(); 18695b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 187048a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18715b6ca027SAl Viro } else { 18725b6ca027SAl Viro path_get(&nd->path); 18735b6ca027SAl Viro } 18745b6ca027SAl Viro return 0; 18755b6ca027SAl Viro } 18765b6ca027SAl Viro 187731e6b01fSNick Piggin nd->root.mnt = NULL; 187831e6b01fSNick Piggin 187948a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 188031e6b01fSNick Piggin if (*name=='/') { 1881e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18828b61e74fSAl Viro rcu_read_lock(); 18837bd88377SAl Viro nd->seq = set_root_rcu(nd); 1884e41f7d4eSAl Viro } else { 1885e41f7d4eSAl Viro set_root(nd); 1886e41f7d4eSAl Viro path_get(&nd->root); 1887e41f7d4eSAl Viro } 188831e6b01fSNick Piggin nd->path = nd->root; 188931e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1890e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 189131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1892c28cc364SNick Piggin unsigned seq; 189331e6b01fSNick Piggin 18948b61e74fSAl Viro rcu_read_lock(); 189531e6b01fSNick Piggin 1896c28cc364SNick Piggin do { 1897c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 189831e6b01fSNick Piggin nd->path = fs->pwd; 1899c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1900c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1901e41f7d4eSAl Viro } else { 1902e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1903e41f7d4eSAl Viro } 190431e6b01fSNick Piggin } else { 1905582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19062903ff01SAl Viro struct fd f = fdget_raw(dfd); 190731e6b01fSNick Piggin struct dentry *dentry; 190831e6b01fSNick Piggin 19092903ff01SAl Viro if (!f.file) 19102903ff01SAl Viro return -EBADF; 191131e6b01fSNick Piggin 19122903ff01SAl Viro dentry = f.file->f_path.dentry; 191331e6b01fSNick Piggin 1914f52e0c11SAl Viro if (*name) { 191544b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19162903ff01SAl Viro fdput(f); 19172903ff01SAl Viro return -ENOTDIR; 1918f52e0c11SAl Viro } 19192903ff01SAl Viro } 19202903ff01SAl Viro 19212903ff01SAl Viro nd->path = f.file->f_path; 1922e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19239c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19242903ff01SAl Viro *fp = f.file; 1925c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19268b61e74fSAl Viro rcu_read_lock(); 19275590ff0dSUlrich Drepper } else { 19282903ff01SAl Viro path_get(&nd->path); 19292903ff01SAl Viro fdput(f); 19301da177e4SLinus Torvalds } 1931e41f7d4eSAl Viro } 1932e41f7d4eSAl Viro 193331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19344023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 19359b4a9b14SAl Viro return 0; 19364023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 19374023bfc9SAl Viro return 0; 19384023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19394023bfc9SAl Viro nd->root.mnt = NULL; 19404023bfc9SAl Viro rcu_read_unlock(); 19414023bfc9SAl Viro return -ECHILD; 19429b4a9b14SAl Viro } 19439b4a9b14SAl Viro 1944bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1945bd92d7feSAl Viro { 1946bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1947bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1948bd92d7feSAl Viro 1949bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 195021b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1951bd92d7feSAl Viro } 1952bd92d7feSAl Viro 19539b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1954ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19559b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19569b4a9b14SAl Viro { 195770e9b357SAl Viro struct file *base = NULL; 1958bd92d7feSAl Viro struct path path; 1959bd92d7feSAl Viro int err; 196031e6b01fSNick Piggin 196131e6b01fSNick Piggin /* 196231e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 196331e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 196431e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 196531e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 196631e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 196731e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 196831e6b01fSNick Piggin * analogue, foo_rcu(). 196931e6b01fSNick Piggin * 197031e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 197131e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 197231e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 197331e6b01fSNick Piggin * be able to complete). 197431e6b01fSNick Piggin */ 1975bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1976ee0827cdSAl Viro 1977bd92d7feSAl Viro if (unlikely(err)) 1978115cbfdcSAl Viro goto out; 1979ee0827cdSAl Viro 1980ee0827cdSAl Viro current->total_link_count = 0; 1981bd92d7feSAl Viro err = link_path_walk(name, nd); 1982bd92d7feSAl Viro 1983bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1984bd92d7feSAl Viro err = lookup_last(nd, &path); 1985bd92d7feSAl Viro while (err > 0) { 1986bd92d7feSAl Viro void *cookie; 1987bd92d7feSAl Viro struct path link = path; 1988800179c9SKees Cook err = may_follow_link(&link, nd); 1989800179c9SKees Cook if (unlikely(err)) 1990800179c9SKees Cook break; 1991bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1992574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19936d7b5aaeSAl Viro if (err) 19946d7b5aaeSAl Viro break; 1995bd92d7feSAl Viro err = lookup_last(nd, &path); 1996574197e0SAl Viro put_link(nd, &link, cookie); 1997bd92d7feSAl Viro } 1998bd92d7feSAl Viro } 1999ee0827cdSAl Viro 20009f1fafeeSAl Viro if (!err) 20019f1fafeeSAl Viro err = complete_walk(nd); 2002bd92d7feSAl Viro 2003bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 200444b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2005bd92d7feSAl Viro path_put(&nd->path); 2006bd23a539SAl Viro err = -ENOTDIR; 2007bd92d7feSAl Viro } 2008bd92d7feSAl Viro } 200916c2cd71SAl Viro 2010115cbfdcSAl Viro out: 201170e9b357SAl Viro if (base) 201270e9b357SAl Viro fput(base); 2013ee0827cdSAl Viro 20145b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 201531e6b01fSNick Piggin path_put(&nd->root); 201631e6b01fSNick Piggin nd->root.mnt = NULL; 201731e6b01fSNick Piggin } 2018bd92d7feSAl Viro return err; 201931e6b01fSNick Piggin } 202031e6b01fSNick Piggin 2021873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2022873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2023873f1eedSJeff Layton { 2024873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 2025873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2026873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 2027873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2028873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 2029873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 2030873f1eedSJeff Layton 2031873f1eedSJeff Layton if (likely(!retval)) 2032adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2033873f1eedSJeff Layton return retval; 2034873f1eedSJeff Layton } 2035873f1eedSJeff Layton 2036ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 2037ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 2038ee0827cdSAl Viro { 2039873f1eedSJeff Layton struct filename filename = { .name = name }; 2040ee0827cdSAl Viro 2041873f1eedSJeff Layton return filename_lookup(dfd, &filename, flags, nd); 20421da177e4SLinus Torvalds } 20431da177e4SLinus Torvalds 204479714f72SAl Viro /* does lookup, returns the object with parent locked */ 204579714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20465590ff0dSUlrich Drepper { 204779714f72SAl Viro struct nameidata nd; 204879714f72SAl Viro struct dentry *d; 204979714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 205079714f72SAl Viro if (err) 205179714f72SAl Viro return ERR_PTR(err); 205279714f72SAl Viro if (nd.last_type != LAST_NORM) { 205379714f72SAl Viro path_put(&nd.path); 205479714f72SAl Viro return ERR_PTR(-EINVAL); 205579714f72SAl Viro } 205679714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20571e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 205879714f72SAl Viro if (IS_ERR(d)) { 205979714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 206079714f72SAl Viro path_put(&nd.path); 206179714f72SAl Viro return d; 206279714f72SAl Viro } 206379714f72SAl Viro *path = nd.path; 206479714f72SAl Viro return d; 20655590ff0dSUlrich Drepper } 20665590ff0dSUlrich Drepper 2067d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2068d1811465SAl Viro { 2069d1811465SAl Viro struct nameidata nd; 2070d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2071d1811465SAl Viro if (!res) 2072d1811465SAl Viro *path = nd.path; 2073d1811465SAl Viro return res; 2074d1811465SAl Viro } 20754d359507SAl Viro EXPORT_SYMBOL(kern_path); 2076d1811465SAl Viro 207716f18200SJosef 'Jeff' Sipek /** 207816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 207916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 208016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 208116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 208216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2083e0a01249SAl Viro * @path: pointer to struct path to fill 208416f18200SJosef 'Jeff' Sipek */ 208516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 208616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2087e0a01249SAl Viro struct path *path) 208816f18200SJosef 'Jeff' Sipek { 2089e0a01249SAl Viro struct nameidata nd; 2090e0a01249SAl Viro int err; 2091e0a01249SAl Viro nd.root.dentry = dentry; 2092e0a01249SAl Viro nd.root.mnt = mnt; 2093e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20945b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2095e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2096e0a01249SAl Viro if (!err) 2097e0a01249SAl Viro *path = nd.path; 2098e0a01249SAl Viro return err; 209916f18200SJosef 'Jeff' Sipek } 21004d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 210116f18200SJosef 'Jeff' Sipek 2102057f6c01SJames Morris /* 2103057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2104057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2105057f6c01SJames Morris * SMP-safe. 2106057f6c01SJames Morris */ 2107a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 21081da177e4SLinus Torvalds { 210972bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 21101da177e4SLinus Torvalds } 21111da177e4SLinus Torvalds 2112eead1911SChristoph Hellwig /** 2113a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2114eead1911SChristoph Hellwig * @name: pathname component to lookup 2115eead1911SChristoph Hellwig * @base: base directory to lookup from 2116eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2117eead1911SChristoph Hellwig * 2118a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2119a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2120eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2121eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2122eead1911SChristoph Hellwig */ 2123057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2124057f6c01SJames Morris { 2125057f6c01SJames Morris struct qstr this; 21266a96ba54SAl Viro unsigned int c; 2127cda309deSMiklos Szeredi int err; 2128057f6c01SJames Morris 21292f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21302f9092e1SDavid Woodhouse 21316a96ba54SAl Viro this.name = name; 21326a96ba54SAl Viro this.len = len; 21330145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21346a96ba54SAl Viro if (!len) 21356a96ba54SAl Viro return ERR_PTR(-EACCES); 21366a96ba54SAl Viro 213721d8a15aSAl Viro if (unlikely(name[0] == '.')) { 213821d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 213921d8a15aSAl Viro return ERR_PTR(-EACCES); 214021d8a15aSAl Viro } 214121d8a15aSAl Viro 21426a96ba54SAl Viro while (len--) { 21436a96ba54SAl Viro c = *(const unsigned char *)name++; 21446a96ba54SAl Viro if (c == '/' || c == '\0') 21456a96ba54SAl Viro return ERR_PTR(-EACCES); 21466a96ba54SAl Viro } 21475a202bcdSAl Viro /* 21485a202bcdSAl Viro * See if the low-level filesystem might want 21495a202bcdSAl Viro * to use its own hash.. 21505a202bcdSAl Viro */ 21515a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2152da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21535a202bcdSAl Viro if (err < 0) 21545a202bcdSAl Viro return ERR_PTR(err); 21555a202bcdSAl Viro } 2156eead1911SChristoph Hellwig 2157cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2158cda309deSMiklos Szeredi if (err) 2159cda309deSMiklos Szeredi return ERR_PTR(err); 2160cda309deSMiklos Szeredi 216172bd866aSAl Viro return __lookup_hash(&this, base, 0); 2162057f6c01SJames Morris } 21634d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2164057f6c01SJames Morris 21651fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21661fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21671da177e4SLinus Torvalds { 21682d8f3038SAl Viro struct nameidata nd; 216991a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21701da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21711da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21722d8f3038SAl Viro 21732d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21742d8f3038SAl Viro 2175873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21761da177e4SLinus Torvalds putname(tmp); 21772d8f3038SAl Viro if (!err) 21782d8f3038SAl Viro *path = nd.path; 21791da177e4SLinus Torvalds } 21801da177e4SLinus Torvalds return err; 21811da177e4SLinus Torvalds } 21821da177e4SLinus Torvalds 21831fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21841fa1e7f6SAndy Whitcroft struct path *path) 21851fa1e7f6SAndy Whitcroft { 2186f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21871fa1e7f6SAndy Whitcroft } 21884d359507SAl Viro EXPORT_SYMBOL(user_path_at); 21891fa1e7f6SAndy Whitcroft 2190873f1eedSJeff Layton /* 2191873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2192873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2193873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2194873f1eedSJeff Layton * path-walking is complete. 2195873f1eedSJeff Layton */ 219691a27b2aSJeff Layton static struct filename * 21979e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 21989e790bd6SJeff Layton unsigned int flags) 21992ad94ae6SAl Viro { 220091a27b2aSJeff Layton struct filename *s = getname(path); 22012ad94ae6SAl Viro int error; 22022ad94ae6SAl Viro 22039e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22049e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22059e790bd6SJeff Layton 22062ad94ae6SAl Viro if (IS_ERR(s)) 220791a27b2aSJeff Layton return s; 22082ad94ae6SAl Viro 22099e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 221091a27b2aSJeff Layton if (error) { 22112ad94ae6SAl Viro putname(s); 221291a27b2aSJeff Layton return ERR_PTR(error); 221391a27b2aSJeff Layton } 22142ad94ae6SAl Viro 221591a27b2aSJeff Layton return s; 22162ad94ae6SAl Viro } 22172ad94ae6SAl Viro 22188033426eSJeff Layton /** 2219197df04cSAl Viro * mountpoint_last - look up last component for umount 22208033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22218033426eSJeff Layton * @path: pointer to container for result 22228033426eSJeff Layton * 22238033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22248033426eSJeff Layton * need to resolve the path without doing any revalidation. 22258033426eSJeff Layton * 22268033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22278033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22288033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22298033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22308033426eSJeff Layton * bogus and it doesn't exist. 22318033426eSJeff Layton * 22328033426eSJeff Layton * Returns: 22338033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22348033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22358033426eSJeff Layton * put in this case. 22368033426eSJeff Layton * 22378033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22388033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22398033426eSJeff Layton * The nd->path reference will also be put. 22408033426eSJeff Layton * 22418033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22428033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22438033426eSJeff Layton * to the link, and nd->path will *not* be put. 22448033426eSJeff Layton */ 22458033426eSJeff Layton static int 2246197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22478033426eSJeff Layton { 22488033426eSJeff Layton int error = 0; 22498033426eSJeff Layton struct dentry *dentry; 22508033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22518033426eSJeff Layton 225235759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 225335759521SAl Viro if (nd->flags & LOOKUP_RCU) { 225435759521SAl Viro if (unlazy_walk(nd, NULL)) { 22558033426eSJeff Layton error = -ECHILD; 225635759521SAl Viro goto out; 225735759521SAl Viro } 22588033426eSJeff Layton } 22598033426eSJeff Layton 22608033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22618033426eSJeff Layton 22628033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22638033426eSJeff Layton error = handle_dots(nd, nd->last_type); 226435759521SAl Viro if (error) 226535759521SAl Viro goto out; 22668033426eSJeff Layton dentry = dget(nd->path.dentry); 226735759521SAl Viro goto done; 22688033426eSJeff Layton } 22698033426eSJeff Layton 22708033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22718033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22728033426eSJeff Layton if (!dentry) { 22738033426eSJeff Layton /* 22748033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22758033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22768033426eSJeff Layton * path doesn't actually point to a mounted dentry. 22778033426eSJeff Layton */ 22788033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22798033426eSJeff Layton if (!dentry) { 22808033426eSJeff Layton error = -ENOMEM; 2281bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 228235759521SAl Viro goto out; 22838033426eSJeff Layton } 228435759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 228535759521SAl Viro error = PTR_ERR(dentry); 2286bcceeebaSDave Jones if (IS_ERR(dentry)) { 2287bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 228835759521SAl Viro goto out; 22898033426eSJeff Layton } 2290bcceeebaSDave Jones } 22918033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 22928033426eSJeff Layton 229335759521SAl Viro done: 229422213318SAl Viro if (!dentry->d_inode || d_is_negative(dentry)) { 22958033426eSJeff Layton error = -ENOENT; 22968033426eSJeff Layton dput(dentry); 229735759521SAl Viro goto out; 229835759521SAl Viro } 22998033426eSJeff Layton path->dentry = dentry; 2300295dc39dSVasily Averin path->mnt = nd->path.mnt; 2301b18825a7SDavid Howells if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) 23028033426eSJeff Layton return 1; 2303295dc39dSVasily Averin mntget(path->mnt); 23048033426eSJeff Layton follow_mount(path); 230535759521SAl Viro error = 0; 230635759521SAl Viro out: 23078033426eSJeff Layton terminate_walk(nd); 23088033426eSJeff Layton return error; 23098033426eSJeff Layton } 23108033426eSJeff Layton 23118033426eSJeff Layton /** 2312197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23138033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23148033426eSJeff Layton * @name: full pathname to walk 2315606d6fe3SRandy Dunlap * @path: pointer to container for result 23168033426eSJeff Layton * @flags: lookup flags 23178033426eSJeff Layton * 23188033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2319606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23208033426eSJeff Layton */ 23218033426eSJeff Layton static int 2322197df04cSAl Viro path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) 23238033426eSJeff Layton { 23248033426eSJeff Layton struct file *base = NULL; 23258033426eSJeff Layton struct nameidata nd; 23268033426eSJeff Layton int err; 23278033426eSJeff Layton 23288033426eSJeff Layton err = path_init(dfd, name, flags | LOOKUP_PARENT, &nd, &base); 23298033426eSJeff Layton if (unlikely(err)) 2330115cbfdcSAl Viro goto out; 23318033426eSJeff Layton 23328033426eSJeff Layton current->total_link_count = 0; 23338033426eSJeff Layton err = link_path_walk(name, &nd); 23348033426eSJeff Layton if (err) 23358033426eSJeff Layton goto out; 23368033426eSJeff Layton 2337197df04cSAl Viro err = mountpoint_last(&nd, path); 23388033426eSJeff Layton while (err > 0) { 23398033426eSJeff Layton void *cookie; 23408033426eSJeff Layton struct path link = *path; 23418033426eSJeff Layton err = may_follow_link(&link, &nd); 23428033426eSJeff Layton if (unlikely(err)) 23438033426eSJeff Layton break; 23448033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 23458033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 23468033426eSJeff Layton if (err) 23478033426eSJeff Layton break; 2348197df04cSAl Viro err = mountpoint_last(&nd, path); 23498033426eSJeff Layton put_link(&nd, &link, cookie); 23508033426eSJeff Layton } 23518033426eSJeff Layton out: 23528033426eSJeff Layton if (base) 23538033426eSJeff Layton fput(base); 23548033426eSJeff Layton 23558033426eSJeff Layton if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT)) 23568033426eSJeff Layton path_put(&nd.root); 23578033426eSJeff Layton 23588033426eSJeff Layton return err; 23598033426eSJeff Layton } 23608033426eSJeff Layton 23612d864651SAl Viro static int 23622d864651SAl Viro filename_mountpoint(int dfd, struct filename *s, struct path *path, 23632d864651SAl Viro unsigned int flags) 23642d864651SAl Viro { 23652d864651SAl Viro int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); 23662d864651SAl Viro if (unlikely(error == -ECHILD)) 23672d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags); 23682d864651SAl Viro if (unlikely(error == -ESTALE)) 23692d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); 23702d864651SAl Viro if (likely(!error)) 23712d864651SAl Viro audit_inode(s, path->dentry, 0); 23722d864651SAl Viro return error; 23732d864651SAl Viro } 23742d864651SAl Viro 23758033426eSJeff Layton /** 2376197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 23778033426eSJeff Layton * @dfd: directory file descriptor 23788033426eSJeff Layton * @name: pathname from userland 23798033426eSJeff Layton * @flags: lookup flags 23808033426eSJeff Layton * @path: pointer to container to hold result 23818033426eSJeff Layton * 23828033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23838033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23848033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23858033426eSJeff Layton * and avoid revalidating the last component. 23868033426eSJeff Layton * 23878033426eSJeff Layton * Returns 0 and populates "path" on success. 23888033426eSJeff Layton */ 23898033426eSJeff Layton int 2390197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 23918033426eSJeff Layton struct path *path) 23928033426eSJeff Layton { 23938033426eSJeff Layton struct filename *s = getname(name); 23948033426eSJeff Layton int error; 23958033426eSJeff Layton if (IS_ERR(s)) 23968033426eSJeff Layton return PTR_ERR(s); 23972d864651SAl Viro error = filename_mountpoint(dfd, s, path, flags); 23988033426eSJeff Layton putname(s); 23998033426eSJeff Layton return error; 24008033426eSJeff Layton } 24018033426eSJeff Layton 24022d864651SAl Viro int 24032d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24042d864651SAl Viro unsigned int flags) 24052d864651SAl Viro { 24062d864651SAl Viro struct filename s = {.name = name}; 24072d864651SAl Viro return filename_mountpoint(dfd, &s, path, flags); 24082d864651SAl Viro } 24092d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24102d864651SAl Viro 2411cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24121da177e4SLinus Torvalds { 24138e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2414da9592edSDavid Howells 24158e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24161da177e4SLinus Torvalds return 0; 24178e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24181da177e4SLinus Torvalds return 0; 241923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24201da177e4SLinus Torvalds } 2421cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24221da177e4SLinus Torvalds 24231da177e4SLinus Torvalds /* 24241da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24251da177e4SLinus Torvalds * whether the type of victim is right. 24261da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24271da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24281da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24291da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24301da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24311da177e4SLinus Torvalds * a. be owner of dir, or 24321da177e4SLinus Torvalds * b. be owner of victim, or 24331da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24341da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24351da177e4SLinus Torvalds * links pointing to it. 24361da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24371da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24381da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24391da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24401da177e4SLinus Torvalds * nfs_async_unlink(). 24411da177e4SLinus Torvalds */ 2442b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24431da177e4SLinus Torvalds { 2444b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24451da177e4SLinus Torvalds int error; 24461da177e4SLinus Torvalds 2447b18825a7SDavid Howells if (d_is_negative(victim)) 24481da177e4SLinus Torvalds return -ENOENT; 2449b18825a7SDavid Howells BUG_ON(!inode); 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24524fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24531da177e4SLinus Torvalds 2454f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24551da177e4SLinus Torvalds if (error) 24561da177e4SLinus Torvalds return error; 24571da177e4SLinus Torvalds if (IS_APPEND(dir)) 24581da177e4SLinus Torvalds return -EPERM; 2459b18825a7SDavid Howells 2460b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2461b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24621da177e4SLinus Torvalds return -EPERM; 24631da177e4SLinus Torvalds if (isdir) { 246444b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24651da177e4SLinus Torvalds return -ENOTDIR; 24661da177e4SLinus Torvalds if (IS_ROOT(victim)) 24671da177e4SLinus Torvalds return -EBUSY; 246844b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24691da177e4SLinus Torvalds return -EISDIR; 24701da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24711da177e4SLinus Torvalds return -ENOENT; 24721da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24731da177e4SLinus Torvalds return -EBUSY; 24741da177e4SLinus Torvalds return 0; 24751da177e4SLinus Torvalds } 24761da177e4SLinus Torvalds 24771da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24781da177e4SLinus Torvalds * dir. 24791da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24801da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24811da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24821da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24831da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24841da177e4SLinus Torvalds */ 2485a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24861da177e4SLinus Torvalds { 248714e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 24881da177e4SLinus Torvalds if (child->d_inode) 24891da177e4SLinus Torvalds return -EEXIST; 24901da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24911da177e4SLinus Torvalds return -ENOENT; 2492f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24931da177e4SLinus Torvalds } 24941da177e4SLinus Torvalds 24951da177e4SLinus Torvalds /* 24961da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24971da177e4SLinus Torvalds */ 24981da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24991da177e4SLinus Torvalds { 25001da177e4SLinus Torvalds struct dentry *p; 25011da177e4SLinus Torvalds 25021da177e4SLinus Torvalds if (p1 == p2) { 2503f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25041da177e4SLinus Torvalds return NULL; 25051da177e4SLinus Torvalds } 25061da177e4SLinus Torvalds 2507a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25081da177e4SLinus Torvalds 2509e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2510e2761a11SOGAWA Hirofumi if (p) { 2511f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2512f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25131da177e4SLinus Torvalds return p; 25141da177e4SLinus Torvalds } 25151da177e4SLinus Torvalds 2516e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2517e2761a11SOGAWA Hirofumi if (p) { 2518f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2519f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25201da177e4SLinus Torvalds return p; 25211da177e4SLinus Torvalds } 25221da177e4SLinus Torvalds 2523f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2524d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25251da177e4SLinus Torvalds return NULL; 25261da177e4SLinus Torvalds } 25274d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25301da177e4SLinus Torvalds { 25311b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25321da177e4SLinus Torvalds if (p1 != p2) { 25331b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2534a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25351da177e4SLinus Torvalds } 25361da177e4SLinus Torvalds } 25374d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25381da177e4SLinus Torvalds 25394acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2540312b63fbSAl Viro bool want_excl) 25411da177e4SLinus Torvalds { 2542a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25431da177e4SLinus Torvalds if (error) 25441da177e4SLinus Torvalds return error; 25451da177e4SLinus Torvalds 2546acfa4380SAl Viro if (!dir->i_op->create) 25471da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25481da177e4SLinus Torvalds mode &= S_IALLUGO; 25491da177e4SLinus Torvalds mode |= S_IFREG; 25501da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25511da177e4SLinus Torvalds if (error) 25521da177e4SLinus Torvalds return error; 2553312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2554a74574aaSStephen Smalley if (!error) 2555f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25561da177e4SLinus Torvalds return error; 25571da177e4SLinus Torvalds } 25584d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25591da177e4SLinus Torvalds 256073d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25611da177e4SLinus Torvalds { 25623fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25631da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25641da177e4SLinus Torvalds int error; 25651da177e4SLinus Torvalds 2566bcda7652SAl Viro /* O_PATH? */ 2567bcda7652SAl Viro if (!acc_mode) 2568bcda7652SAl Viro return 0; 2569bcda7652SAl Viro 25701da177e4SLinus Torvalds if (!inode) 25711da177e4SLinus Torvalds return -ENOENT; 25721da177e4SLinus Torvalds 2573c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2574c8fe8f30SChristoph Hellwig case S_IFLNK: 25751da177e4SLinus Torvalds return -ELOOP; 2576c8fe8f30SChristoph Hellwig case S_IFDIR: 2577c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25781da177e4SLinus Torvalds return -EISDIR; 2579c8fe8f30SChristoph Hellwig break; 2580c8fe8f30SChristoph Hellwig case S_IFBLK: 2581c8fe8f30SChristoph Hellwig case S_IFCHR: 25823fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25831da177e4SLinus Torvalds return -EACCES; 2584c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2585c8fe8f30SChristoph Hellwig case S_IFIFO: 2586c8fe8f30SChristoph Hellwig case S_IFSOCK: 25871da177e4SLinus Torvalds flag &= ~O_TRUNC; 2588c8fe8f30SChristoph Hellwig break; 25894a3fd211SDave Hansen } 2590b41572e9SDave Hansen 25913fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2592b41572e9SDave Hansen if (error) 2593b41572e9SDave Hansen return error; 25946146f0d5SMimi Zohar 25951da177e4SLinus Torvalds /* 25961da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25971da177e4SLinus Torvalds */ 25981da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25998737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26007715b521SAl Viro return -EPERM; 26011da177e4SLinus Torvalds if (flag & O_TRUNC) 26027715b521SAl Viro return -EPERM; 26031da177e4SLinus Torvalds } 26041da177e4SLinus Torvalds 26051da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26062e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26077715b521SAl Viro return -EPERM; 26081da177e4SLinus Torvalds 2609f3c7691eSJ. Bruce Fields return 0; 26107715b521SAl Viro } 26117715b521SAl Viro 2612e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26137715b521SAl Viro { 2614e1181ee6SJeff Layton struct path *path = &filp->f_path; 26157715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26167715b521SAl Viro int error = get_write_access(inode); 26171da177e4SLinus Torvalds if (error) 26187715b521SAl Viro return error; 26191da177e4SLinus Torvalds /* 26201da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26211da177e4SLinus Torvalds */ 2622d7a06983SJeff Layton error = locks_verify_locked(filp); 2623be6d3e56SKentaro Takeda if (!error) 2624ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26251da177e4SLinus Torvalds if (!error) { 26267715b521SAl Viro error = do_truncate(path->dentry, 0, 2627d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2628e1181ee6SJeff Layton filp); 26291da177e4SLinus Torvalds } 26301da177e4SLinus Torvalds put_write_access(inode); 2631acd0c935SMimi Zohar return error; 26321da177e4SLinus Torvalds } 26331da177e4SLinus Torvalds 2634d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2635d57999e1SDave Hansen { 26368a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26378a5e929dSAl Viro flag--; 2638d57999e1SDave Hansen return flag; 2639d57999e1SDave Hansen } 2640d57999e1SDave Hansen 2641d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2642d18e9008SMiklos Szeredi { 2643d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2644d18e9008SMiklos Szeredi if (error) 2645d18e9008SMiklos Szeredi return error; 2646d18e9008SMiklos Szeredi 2647d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2648d18e9008SMiklos Szeredi if (error) 2649d18e9008SMiklos Szeredi return error; 2650d18e9008SMiklos Szeredi 2651d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2652d18e9008SMiklos Szeredi } 2653d18e9008SMiklos Szeredi 26541acf0af9SDavid Howells /* 26551acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26561acf0af9SDavid Howells * dentry. 26571acf0af9SDavid Howells * 26581acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26591acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26601acf0af9SDavid Howells * 26611acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26621acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26631acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26641acf0af9SDavid Howells * 26651acf0af9SDavid Howells * Returns an error code otherwise. 26661acf0af9SDavid Howells */ 26672675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 266830d90494SAl Viro struct path *path, struct file *file, 2669015c3bbcSMiklos Szeredi const struct open_flags *op, 267064894cf8SAl Viro bool got_write, bool need_lookup, 267147237687SAl Viro int *opened) 2672d18e9008SMiklos Szeredi { 2673d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2674d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2675d18e9008SMiklos Szeredi umode_t mode; 2676d18e9008SMiklos Szeredi int error; 2677d18e9008SMiklos Szeredi int acc_mode; 2678d18e9008SMiklos Szeredi int create_error = 0; 2679d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2680116cc022SMiklos Szeredi bool excl; 2681d18e9008SMiklos Szeredi 2682d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2683d18e9008SMiklos Szeredi 2684d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2685d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26862675a4ebSAl Viro error = -ENOENT; 2687d18e9008SMiklos Szeredi goto out; 2688d18e9008SMiklos Szeredi } 2689d18e9008SMiklos Szeredi 269062b259d8SMiklos Szeredi mode = op->mode; 2691d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2692d18e9008SMiklos Szeredi mode &= ~current_umask(); 2693d18e9008SMiklos Szeredi 2694116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2695116cc022SMiklos Szeredi if (excl) 2696d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2697d18e9008SMiklos Szeredi 2698d18e9008SMiklos Szeredi /* 2699d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2700d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2701d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2702d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2703d18e9008SMiklos Szeredi * 2704d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2705d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2706d18e9008SMiklos Szeredi */ 270764894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 270864894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 270964894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2710d18e9008SMiklos Szeredi /* 2711d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2712d18e9008SMiklos Szeredi * back to lookup + open 2713d18e9008SMiklos Szeredi */ 2714d18e9008SMiklos Szeredi goto no_open; 2715d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2716d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 271764894cf8SAl Viro create_error = -EROFS; 2718d18e9008SMiklos Szeredi goto no_open; 2719d18e9008SMiklos Szeredi } else { 2720d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 272164894cf8SAl Viro create_error = -EROFS; 2722d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2723d18e9008SMiklos Szeredi } 2724d18e9008SMiklos Szeredi } 2725d18e9008SMiklos Szeredi 2726d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 272738227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2728d18e9008SMiklos Szeredi if (error) { 2729d18e9008SMiklos Szeredi create_error = error; 2730d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2731d18e9008SMiklos Szeredi goto no_open; 2732d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2733d18e9008SMiklos Szeredi } 2734d18e9008SMiklos Szeredi } 2735d18e9008SMiklos Szeredi 2736d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2737d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2738d18e9008SMiklos Szeredi 273930d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 274030d90494SAl Viro file->f_path.mnt = nd->path.mnt; 274130d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 274247237687SAl Viro opened); 2743d9585277SAl Viro if (error < 0) { 2744d9585277SAl Viro if (create_error && error == -ENOENT) 2745d9585277SAl Viro error = create_error; 2746d18e9008SMiklos Szeredi goto out; 2747d18e9008SMiklos Szeredi } 2748d18e9008SMiklos Szeredi 2749d9585277SAl Viro if (error) { /* returned 1, that is */ 275030d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27512675a4ebSAl Viro error = -EIO; 2752d18e9008SMiklos Szeredi goto out; 2753d18e9008SMiklos Szeredi } 275430d90494SAl Viro if (file->f_path.dentry) { 2755d18e9008SMiklos Szeredi dput(dentry); 275630d90494SAl Viro dentry = file->f_path.dentry; 2757d18e9008SMiklos Szeredi } 275803da633aSAl Viro if (*opened & FILE_CREATED) 275903da633aSAl Viro fsnotify_create(dir, dentry); 276003da633aSAl Viro if (!dentry->d_inode) { 276103da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 276203da633aSAl Viro if (create_error) { 276362b2ce96SSage Weil error = create_error; 276462b2ce96SSage Weil goto out; 276562b2ce96SSage Weil } 276603da633aSAl Viro } else { 276703da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 276803da633aSAl Viro error = -EEXIST; 276903da633aSAl Viro goto out; 277003da633aSAl Viro } 277103da633aSAl Viro } 2772d18e9008SMiklos Szeredi goto looked_up; 2773d18e9008SMiklos Szeredi } 2774d18e9008SMiklos Szeredi 2775d18e9008SMiklos Szeredi /* 2776d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2777d18e9008SMiklos Szeredi * here. 2778d18e9008SMiklos Szeredi */ 277903da633aSAl Viro acc_mode = op->acc_mode; 278003da633aSAl Viro if (*opened & FILE_CREATED) { 278103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 278203da633aSAl Viro fsnotify_create(dir, dentry); 278303da633aSAl Viro acc_mode = MAY_OPEN; 278403da633aSAl Viro } 27852675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27862675a4ebSAl Viro if (error) 27872675a4ebSAl Viro fput(file); 2788d18e9008SMiklos Szeredi 2789d18e9008SMiklos Szeredi out: 2790d18e9008SMiklos Szeredi dput(dentry); 27912675a4ebSAl Viro return error; 2792d18e9008SMiklos Szeredi 2793d18e9008SMiklos Szeredi no_open: 2794d18e9008SMiklos Szeredi if (need_lookup) { 279572bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2796d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27972675a4ebSAl Viro return PTR_ERR(dentry); 2798d18e9008SMiklos Szeredi 2799d18e9008SMiklos Szeredi if (create_error) { 2800d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2801d18e9008SMiklos Szeredi 28022675a4ebSAl Viro error = create_error; 2803d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2804d18e9008SMiklos Szeredi if (!dentry->d_inode) 2805d18e9008SMiklos Szeredi goto out; 2806d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2807d18e9008SMiklos Szeredi goto out; 2808d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2809d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2810d18e9008SMiklos Szeredi goto out; 2811d18e9008SMiklos Szeredi } 2812d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2813d18e9008SMiklos Szeredi } 2814d18e9008SMiklos Szeredi } 2815d18e9008SMiklos Szeredi looked_up: 2816d18e9008SMiklos Szeredi path->dentry = dentry; 2817d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28182675a4ebSAl Viro return 1; 2819d18e9008SMiklos Szeredi } 2820d18e9008SMiklos Szeredi 282131e6b01fSNick Piggin /* 28221acf0af9SDavid Howells * Look up and maybe create and open the last component. 2823d58ffd35SMiklos Szeredi * 2824d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2825d58ffd35SMiklos Szeredi * 28261acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28271acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28281acf0af9SDavid Howells * 28291acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28301acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28311acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28321acf0af9SDavid Howells * specified then a negative dentry may be returned. 28331acf0af9SDavid Howells * 28341acf0af9SDavid Howells * An error code is returned otherwise. 28351acf0af9SDavid Howells * 28361acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28371acf0af9SDavid Howells * cleared otherwise prior to returning. 2838d58ffd35SMiklos Szeredi */ 28392675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 284030d90494SAl Viro struct file *file, 2841d58ffd35SMiklos Szeredi const struct open_flags *op, 284264894cf8SAl Viro bool got_write, int *opened) 2843d58ffd35SMiklos Szeredi { 2844d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 284554ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2846d58ffd35SMiklos Szeredi struct dentry *dentry; 2847d58ffd35SMiklos Szeredi int error; 284854ef4872SMiklos Szeredi bool need_lookup; 2849d58ffd35SMiklos Szeredi 285047237687SAl Viro *opened &= ~FILE_CREATED; 2851201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2852d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28532675a4ebSAl Viro return PTR_ERR(dentry); 2854d58ffd35SMiklos Szeredi 2855d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2856d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2857d18e9008SMiklos Szeredi goto out_no_open; 2858d18e9008SMiklos Szeredi 2859d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 286064894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 286147237687SAl Viro need_lookup, opened); 2862d18e9008SMiklos Szeredi } 2863d18e9008SMiklos Szeredi 286454ef4872SMiklos Szeredi if (need_lookup) { 286554ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 286654ef4872SMiklos Szeredi 286772bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 286854ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28692675a4ebSAl Viro return PTR_ERR(dentry); 287054ef4872SMiklos Szeredi } 287154ef4872SMiklos Szeredi 2872d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2873d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2874d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2875d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2876d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2877d58ffd35SMiklos Szeredi /* 2878d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2879d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2880d58ffd35SMiklos Szeredi * the time when the file is created and when 2881d58ffd35SMiklos Szeredi * a permanent write count is taken through 2882015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2883d58ffd35SMiklos Szeredi */ 288464894cf8SAl Viro if (!got_write) { 288564894cf8SAl Viro error = -EROFS; 2886d58ffd35SMiklos Szeredi goto out_dput; 288764894cf8SAl Viro } 288847237687SAl Viro *opened |= FILE_CREATED; 2889d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2890d58ffd35SMiklos Szeredi if (error) 2891d58ffd35SMiklos Szeredi goto out_dput; 2892312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2893312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2894d58ffd35SMiklos Szeredi if (error) 2895d58ffd35SMiklos Szeredi goto out_dput; 2896d58ffd35SMiklos Szeredi } 2897d18e9008SMiklos Szeredi out_no_open: 2898d58ffd35SMiklos Szeredi path->dentry = dentry; 2899d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29002675a4ebSAl Viro return 1; 2901d58ffd35SMiklos Szeredi 2902d58ffd35SMiklos Szeredi out_dput: 2903d58ffd35SMiklos Szeredi dput(dentry); 29042675a4ebSAl Viro return error; 2905d58ffd35SMiklos Szeredi } 2906d58ffd35SMiklos Szeredi 2907d58ffd35SMiklos Szeredi /* 2908fe2d35ffSAl Viro * Handle the last step of open() 290931e6b01fSNick Piggin */ 29102675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 291130d90494SAl Viro struct file *file, const struct open_flags *op, 2912669abf4eSJeff Layton int *opened, struct filename *name) 2913fb1cc555SAl Viro { 2914a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2915ca344a89SAl Viro int open_flag = op->open_flag; 291677d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 291764894cf8SAl Viro bool got_write = false; 2918bcda7652SAl Viro int acc_mode = op->acc_mode; 2919a1eb3315SMiklos Szeredi struct inode *inode; 292077d660a8SMiklos Szeredi bool symlink_ok = false; 292116b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 292216b1c1cdSMiklos Szeredi bool retried = false; 292316c2cd71SAl Viro int error; 2924fb1cc555SAl Viro 2925c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2926c3e380b0SAl Viro nd->flags |= op->intent; 2927c3e380b0SAl Viro 2928bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2929fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2930fe2d35ffSAl Viro if (error) 29312675a4ebSAl Viro return error; 2932e83db167SMiklos Szeredi goto finish_open; 29331f36f774SAl Viro } 2934a2c36b45SAl Viro 2935ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2936fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2937fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2938bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 293977d660a8SMiklos Szeredi symlink_ok = true; 2940fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2941e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 294271574865SMiklos Szeredi if (likely(!error)) 294371574865SMiklos Szeredi goto finish_lookup; 294471574865SMiklos Szeredi 2945ce57dfc1SAl Viro if (error < 0) 29462675a4ebSAl Viro goto out; 2947a1eb3315SMiklos Szeredi 294837d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2949b6183df7SMiklos Szeredi } else { 2950fe2d35ffSAl Viro /* create side of things */ 2951a3fbbde7SAl Viro /* 2952b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2953b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2954b6183df7SMiklos Szeredi * about to look up 2955a3fbbde7SAl Viro */ 29569f1fafeeSAl Viro error = complete_walk(nd); 29579f1fafeeSAl Viro if (error) 29582675a4ebSAl Viro return error; 2959fe2d35ffSAl Viro 296033e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 296116c2cd71SAl Viro error = -EISDIR; 29621f36f774SAl Viro /* trailing slashes? */ 296331e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29642675a4ebSAl Viro goto out; 2965b6183df7SMiklos Szeredi } 29661f36f774SAl Viro 296716b1c1cdSMiklos Szeredi retry_lookup: 296864894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 296964894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 297064894cf8SAl Viro if (!error) 297164894cf8SAl Viro got_write = true; 297264894cf8SAl Viro /* 297364894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 297464894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 297564894cf8SAl Viro * dropping this one anyway. 297664894cf8SAl Viro */ 297764894cf8SAl Viro } 2978a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 297964894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2980fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2981fb1cc555SAl Viro 29822675a4ebSAl Viro if (error <= 0) { 29832675a4ebSAl Viro if (error) 2984d58ffd35SMiklos Szeredi goto out; 29856c0d46c4SAl Viro 298647237687SAl Viro if ((*opened & FILE_CREATED) || 2987496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 298877d660a8SMiklos Szeredi will_truncate = false; 2989d18e9008SMiklos Szeredi 2990adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2991d18e9008SMiklos Szeredi goto opened; 2992d18e9008SMiklos Szeredi } 2993d18e9008SMiklos Szeredi 299447237687SAl Viro if (*opened & FILE_CREATED) { 29959b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2996ca344a89SAl Viro open_flag &= ~O_TRUNC; 299777d660a8SMiklos Szeredi will_truncate = false; 2998bcda7652SAl Viro acc_mode = MAY_OPEN; 2999d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 3000e83db167SMiklos Szeredi goto finish_open_created; 3001fb1cc555SAl Viro } 3002fb1cc555SAl Viro 3003fb1cc555SAl Viro /* 30043134f37eSJeff Layton * create/update audit record if it already exists. 3005fb1cc555SAl Viro */ 3006b18825a7SDavid Howells if (d_is_positive(path->dentry)) 3007adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 3008fb1cc555SAl Viro 3009d18e9008SMiklos Szeredi /* 3010d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3011d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3012d18e9008SMiklos Szeredi * necessary...) 3013d18e9008SMiklos Szeredi */ 301464894cf8SAl Viro if (got_write) { 3015d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 301664894cf8SAl Viro got_write = false; 3017d18e9008SMiklos Szeredi } 3018d18e9008SMiklos Szeredi 3019fb1cc555SAl Viro error = -EEXIST; 3020f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3021fb1cc555SAl Viro goto exit_dput; 3022fb1cc555SAl Viro 30239875cf80SDavid Howells error = follow_managed(path, nd->flags); 30249875cf80SDavid Howells if (error < 0) 3025fb1cc555SAl Viro goto exit_dput; 3026fb1cc555SAl Viro 3027a3fbbde7SAl Viro if (error) 3028a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3029a3fbbde7SAl Viro 3030decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3031decf3400SMiklos Szeredi inode = path->dentry->d_inode; 30325f5daac1SMiklos Szeredi finish_lookup: 30335f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 3034fb1cc555SAl Viro error = -ENOENT; 303522213318SAl Viro if (!inode || d_is_negative(path->dentry)) { 303654c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 30372675a4ebSAl Viro goto out; 303854c33e7fSMiklos Szeredi } 30399e67f361SAl Viro 3040b18825a7SDavid Howells if (should_follow_link(path->dentry, !symlink_ok)) { 3041d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3042d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 3043d45ea867SMiklos Szeredi error = -ECHILD; 30442675a4ebSAl Viro goto out; 3045d45ea867SMiklos Szeredi } 3046d45ea867SMiklos Szeredi } 3047d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 30482675a4ebSAl Viro return 1; 3049d45ea867SMiklos Szeredi } 3050fb1cc555SAl Viro 305116b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 3052fb1cc555SAl Viro path_to_nameidata(path, nd); 305316b1c1cdSMiklos Szeredi } else { 305416b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 305516b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 305616b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 305716b1c1cdSMiklos Szeredi 305816b1c1cdSMiklos Szeredi } 3059decf3400SMiklos Szeredi nd->inode = inode; 3060a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3061bc77daa7SAl Viro finish_open: 3062a3fbbde7SAl Viro error = complete_walk(nd); 306316b1c1cdSMiklos Szeredi if (error) { 306416b1c1cdSMiklos Szeredi path_put(&save_parent); 30652675a4ebSAl Viro return error; 306616b1c1cdSMiklos Szeredi } 3067bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3068fb1cc555SAl Viro error = -EISDIR; 306944b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 30702675a4ebSAl Viro goto out; 3071af2f5542SMiklos Szeredi error = -ENOTDIR; 307244b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 30732675a4ebSAl Viro goto out; 30746c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 307577d660a8SMiklos Szeredi will_truncate = false; 30766c0d46c4SAl Viro 30770f9d1a10SAl Viro if (will_truncate) { 30780f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30790f9d1a10SAl Viro if (error) 30802675a4ebSAl Viro goto out; 308164894cf8SAl Viro got_write = true; 30820f9d1a10SAl Viro } 3083e83db167SMiklos Szeredi finish_open_created: 3084bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3085ca344a89SAl Viro if (error) 30862675a4ebSAl Viro goto out; 30874aa7c634SMiklos Szeredi 30884aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 30894aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 30904aa7c634SMiklos Szeredi if (!error) { 30914aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 30924aa7c634SMiklos Szeredi } else { 309330d90494SAl Viro if (error == -EOPENSTALE) 3094f60dc3dbSMiklos Szeredi goto stale_open; 3095015c3bbcSMiklos Szeredi goto out; 3096f60dc3dbSMiklos Szeredi } 3097a8277b9bSMiklos Szeredi opened: 30982675a4ebSAl Viro error = open_check_o_direct(file); 3099015c3bbcSMiklos Szeredi if (error) 3100015c3bbcSMiklos Szeredi goto exit_fput; 31013034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3102aa4caadbSMiklos Szeredi if (error) 3103aa4caadbSMiklos Szeredi goto exit_fput; 3104aa4caadbSMiklos Szeredi 31050f9d1a10SAl Viro if (will_truncate) { 31062675a4ebSAl Viro error = handle_truncate(file); 3107aa4caadbSMiklos Szeredi if (error) 3108aa4caadbSMiklos Szeredi goto exit_fput; 31090f9d1a10SAl Viro } 3110ca344a89SAl Viro out: 311164894cf8SAl Viro if (got_write) 31120f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 311316b1c1cdSMiklos Szeredi path_put(&save_parent); 3114e276ae67SMiklos Szeredi terminate_walk(nd); 31152675a4ebSAl Viro return error; 3116fb1cc555SAl Viro 3117fb1cc555SAl Viro exit_dput: 3118fb1cc555SAl Viro path_put_conditional(path, nd); 3119ca344a89SAl Viro goto out; 3120015c3bbcSMiklos Szeredi exit_fput: 31212675a4ebSAl Viro fput(file); 31222675a4ebSAl Viro goto out; 3123015c3bbcSMiklos Szeredi 3124f60dc3dbSMiklos Szeredi stale_open: 3125f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3126f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3127f60dc3dbSMiklos Szeredi goto out; 3128f60dc3dbSMiklos Szeredi 3129f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3130f60dc3dbSMiklos Szeredi path_put(&nd->path); 3131f60dc3dbSMiklos Szeredi nd->path = save_parent; 3132f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3133f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3134f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 313564894cf8SAl Viro if (got_write) { 3136f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 313764894cf8SAl Viro got_write = false; 3138f60dc3dbSMiklos Szeredi } 3139f60dc3dbSMiklos Szeredi retried = true; 3140f60dc3dbSMiklos Szeredi goto retry_lookup; 3141fb1cc555SAl Viro } 3142fb1cc555SAl Viro 314360545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 314460545d0dSAl Viro struct nameidata *nd, int flags, 314560545d0dSAl Viro const struct open_flags *op, 314660545d0dSAl Viro struct file *file, int *opened) 314760545d0dSAl Viro { 314860545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 314960545d0dSAl Viro struct dentry *dentry, *child; 315060545d0dSAl Viro struct inode *dir; 315160545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 315260545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 315360545d0dSAl Viro if (unlikely(error)) 315460545d0dSAl Viro return error; 315560545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 315660545d0dSAl Viro if (unlikely(error)) 315760545d0dSAl Viro goto out; 315860545d0dSAl Viro /* we want directory to be writable */ 315960545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 316060545d0dSAl Viro if (error) 316160545d0dSAl Viro goto out2; 316260545d0dSAl Viro dentry = nd->path.dentry; 316360545d0dSAl Viro dir = dentry->d_inode; 316460545d0dSAl Viro if (!dir->i_op->tmpfile) { 316560545d0dSAl Viro error = -EOPNOTSUPP; 316660545d0dSAl Viro goto out2; 316760545d0dSAl Viro } 316860545d0dSAl Viro child = d_alloc(dentry, &name); 316960545d0dSAl Viro if (unlikely(!child)) { 317060545d0dSAl Viro error = -ENOMEM; 317160545d0dSAl Viro goto out2; 317260545d0dSAl Viro } 317360545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 317460545d0dSAl Viro nd->flags |= op->intent; 317560545d0dSAl Viro dput(nd->path.dentry); 317660545d0dSAl Viro nd->path.dentry = child; 317760545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 317860545d0dSAl Viro if (error) 317960545d0dSAl Viro goto out2; 318060545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 318169a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 318269a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 318360545d0dSAl Viro if (error) 318460545d0dSAl Viro goto out2; 318560545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 318660545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 318760545d0dSAl Viro if (error) 318860545d0dSAl Viro goto out2; 318960545d0dSAl Viro error = open_check_o_direct(file); 3190f4e0c30cSAl Viro if (error) { 319160545d0dSAl Viro fput(file); 3192f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3193f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3194f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3195f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3196f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3197f4e0c30cSAl Viro } 319860545d0dSAl Viro out2: 319960545d0dSAl Viro mnt_drop_write(nd->path.mnt); 320060545d0dSAl Viro out: 320160545d0dSAl Viro path_put(&nd->path); 320260545d0dSAl Viro return error; 320360545d0dSAl Viro } 320460545d0dSAl Viro 3205669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 320673d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32071da177e4SLinus Torvalds { 3208fe2d35ffSAl Viro struct file *base = NULL; 320930d90494SAl Viro struct file *file; 32109850c056SAl Viro struct path path; 321147237687SAl Viro int opened = 0; 321213aab428SAl Viro int error; 321331e6b01fSNick Piggin 321430d90494SAl Viro file = get_empty_filp(); 32151afc99beSAl Viro if (IS_ERR(file)) 32161afc99beSAl Viro return file; 321731e6b01fSNick Piggin 321830d90494SAl Viro file->f_flags = op->open_flag; 321931e6b01fSNick Piggin 3220bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 322160545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 322260545d0dSAl Viro goto out; 322360545d0dSAl Viro } 322460545d0dSAl Viro 3225669abf4eSJeff Layton error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); 322631e6b01fSNick Piggin if (unlikely(error)) 32272675a4ebSAl Viro goto out; 322831e6b01fSNick Piggin 3229fe2d35ffSAl Viro current->total_link_count = 0; 3230669abf4eSJeff Layton error = link_path_walk(pathname->name, nd); 323131e6b01fSNick Piggin if (unlikely(error)) 32322675a4ebSAl Viro goto out; 32331da177e4SLinus Torvalds 32342675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 32352675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 32367b9337aaSNick Piggin struct path link = path; 3237def4af30SAl Viro void *cookie; 3238574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 323973d049a4SAl Viro path_put_conditional(&path, nd); 324073d049a4SAl Viro path_put(&nd->path); 32412675a4ebSAl Viro error = -ELOOP; 324240b39136SAl Viro break; 324340b39136SAl Viro } 3244800179c9SKees Cook error = may_follow_link(&link, nd); 3245800179c9SKees Cook if (unlikely(error)) 3246800179c9SKees Cook break; 324773d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 324873d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3249574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3250c3e380b0SAl Viro if (unlikely(error)) 32512675a4ebSAl Viro break; 32522675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3253574197e0SAl Viro put_link(nd, &link, cookie); 3254806b681cSAl Viro } 325510fa8e62SAl Viro out: 325673d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 325773d049a4SAl Viro path_put(&nd->root); 3258fe2d35ffSAl Viro if (base) 3259fe2d35ffSAl Viro fput(base); 32602675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32612675a4ebSAl Viro BUG_ON(!error); 326230d90494SAl Viro put_filp(file); 3263015c3bbcSMiklos Szeredi } 32642675a4ebSAl Viro if (unlikely(error)) { 32652675a4ebSAl Viro if (error == -EOPENSTALE) { 32662675a4ebSAl Viro if (flags & LOOKUP_RCU) 32672675a4ebSAl Viro error = -ECHILD; 32682675a4ebSAl Viro else 32692675a4ebSAl Viro error = -ESTALE; 32702675a4ebSAl Viro } 32712675a4ebSAl Viro file = ERR_PTR(error); 32722675a4ebSAl Viro } 32732675a4ebSAl Viro return file; 3274de459215SKirill Korotaev } 32751da177e4SLinus Torvalds 3276669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3277f9652e10SAl Viro const struct open_flags *op) 327813aab428SAl Viro { 327973d049a4SAl Viro struct nameidata nd; 3280f9652e10SAl Viro int flags = op->lookup_flags; 328113aab428SAl Viro struct file *filp; 328213aab428SAl Viro 328373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 328413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 328573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 328613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 328773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 328813aab428SAl Viro return filp; 328913aab428SAl Viro } 329013aab428SAl Viro 329173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3292f9652e10SAl Viro const char *name, const struct open_flags *op) 329373d049a4SAl Viro { 329473d049a4SAl Viro struct nameidata nd; 329573d049a4SAl Viro struct file *file; 3296669abf4eSJeff Layton struct filename filename = { .name = name }; 3297f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 329873d049a4SAl Viro 329973d049a4SAl Viro nd.root.mnt = mnt; 330073d049a4SAl Viro nd.root.dentry = dentry; 330173d049a4SAl Viro 3302b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 330373d049a4SAl Viro return ERR_PTR(-ELOOP); 330473d049a4SAl Viro 3305669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); 330673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3307669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags); 330873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3309669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); 331073d049a4SAl Viro return file; 331173d049a4SAl Viro } 331273d049a4SAl Viro 33131ac12b4bSJeff Layton struct dentry *kern_path_create(int dfd, const char *pathname, 33141ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33151da177e4SLinus Torvalds { 3316c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3317ed75e95dSAl Viro struct nameidata nd; 3318c30dabfeSJan Kara int err2; 33191ac12b4bSJeff Layton int error; 33201ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33211ac12b4bSJeff Layton 33221ac12b4bSJeff Layton /* 33231ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33241ac12b4bSJeff Layton * other flags passed in are ignored! 33251ac12b4bSJeff Layton */ 33261ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33271ac12b4bSJeff Layton 33281ac12b4bSJeff Layton error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); 3329ed75e95dSAl Viro if (error) 3330ed75e95dSAl Viro return ERR_PTR(error); 33311da177e4SLinus Torvalds 3332c663e5d8SChristoph Hellwig /* 3333c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3334c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3335c663e5d8SChristoph Hellwig */ 3336ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3337ed75e95dSAl Viro goto out; 3338ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3339ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3340c663e5d8SChristoph Hellwig 3341c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3342c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3343c663e5d8SChristoph Hellwig /* 3344c663e5d8SChristoph Hellwig * Do the final lookup. 3345c663e5d8SChristoph Hellwig */ 3346ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3347ed75e95dSAl Viro dentry = lookup_hash(&nd); 33481da177e4SLinus Torvalds if (IS_ERR(dentry)) 3349a8104a9fSAl Viro goto unlock; 3350c663e5d8SChristoph Hellwig 3351a8104a9fSAl Viro error = -EEXIST; 3352b18825a7SDavid Howells if (d_is_positive(dentry)) 3353a8104a9fSAl Viro goto fail; 3354b18825a7SDavid Howells 3355c663e5d8SChristoph Hellwig /* 3356c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3357c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3358c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3359c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3360c663e5d8SChristoph Hellwig */ 3361ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3362a8104a9fSAl Viro error = -ENOENT; 3363ed75e95dSAl Viro goto fail; 3364e9baf6e5SAl Viro } 3365c30dabfeSJan Kara if (unlikely(err2)) { 3366c30dabfeSJan Kara error = err2; 3367a8104a9fSAl Viro goto fail; 3368c30dabfeSJan Kara } 3369ed75e95dSAl Viro *path = nd.path; 3370e9baf6e5SAl Viro return dentry; 33711da177e4SLinus Torvalds fail: 3372a8104a9fSAl Viro dput(dentry); 3373a8104a9fSAl Viro dentry = ERR_PTR(error); 3374a8104a9fSAl Viro unlock: 3375dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3376c30dabfeSJan Kara if (!err2) 3377c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3378ed75e95dSAl Viro out: 3379dae6ad8fSAl Viro path_put(&nd.path); 3380ed75e95dSAl Viro return dentry; 3381dae6ad8fSAl Viro } 3382dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3383dae6ad8fSAl Viro 3384921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3385921a1650SAl Viro { 3386921a1650SAl Viro dput(dentry); 3387921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3388a8104a9fSAl Viro mnt_drop_write(path->mnt); 3389921a1650SAl Viro path_put(path); 3390921a1650SAl Viro } 3391921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3392921a1650SAl Viro 33931ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33941ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3395dae6ad8fSAl Viro { 339691a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3397dae6ad8fSAl Viro struct dentry *res; 3398dae6ad8fSAl Viro if (IS_ERR(tmp)) 3399dae6ad8fSAl Viro return ERR_CAST(tmp); 34001ac12b4bSJeff Layton res = kern_path_create(dfd, tmp->name, path, lookup_flags); 3401dae6ad8fSAl Viro putname(tmp); 3402dae6ad8fSAl Viro return res; 3403dae6ad8fSAl Viro } 3404dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3405dae6ad8fSAl Viro 34061a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34071da177e4SLinus Torvalds { 3408a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34091da177e4SLinus Torvalds 34101da177e4SLinus Torvalds if (error) 34111da177e4SLinus Torvalds return error; 34121da177e4SLinus Torvalds 3413975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34141da177e4SLinus Torvalds return -EPERM; 34151da177e4SLinus Torvalds 3416acfa4380SAl Viro if (!dir->i_op->mknod) 34171da177e4SLinus Torvalds return -EPERM; 34181da177e4SLinus Torvalds 341908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 342008ce5f16SSerge E. Hallyn if (error) 342108ce5f16SSerge E. Hallyn return error; 342208ce5f16SSerge E. Hallyn 34231da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34241da177e4SLinus Torvalds if (error) 34251da177e4SLinus Torvalds return error; 34261da177e4SLinus Torvalds 34271da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3428a74574aaSStephen Smalley if (!error) 3429f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34301da177e4SLinus Torvalds return error; 34311da177e4SLinus Torvalds } 34324d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34331da177e4SLinus Torvalds 3434f69aac00SAl Viro static int may_mknod(umode_t mode) 3435463c3197SDave Hansen { 3436463c3197SDave Hansen switch (mode & S_IFMT) { 3437463c3197SDave Hansen case S_IFREG: 3438463c3197SDave Hansen case S_IFCHR: 3439463c3197SDave Hansen case S_IFBLK: 3440463c3197SDave Hansen case S_IFIFO: 3441463c3197SDave Hansen case S_IFSOCK: 3442463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3443463c3197SDave Hansen return 0; 3444463c3197SDave Hansen case S_IFDIR: 3445463c3197SDave Hansen return -EPERM; 3446463c3197SDave Hansen default: 3447463c3197SDave Hansen return -EINVAL; 3448463c3197SDave Hansen } 3449463c3197SDave Hansen } 3450463c3197SDave Hansen 34518208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34522e4d0924SHeiko Carstens unsigned, dev) 34531da177e4SLinus Torvalds { 34541da177e4SLinus Torvalds struct dentry *dentry; 3455dae6ad8fSAl Viro struct path path; 3456dae6ad8fSAl Viro int error; 3457972567f1SJeff Layton unsigned int lookup_flags = 0; 34581da177e4SLinus Torvalds 34598e4bfca1SAl Viro error = may_mknod(mode); 34608e4bfca1SAl Viro if (error) 34618e4bfca1SAl Viro return error; 3462972567f1SJeff Layton retry: 3463972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3464dae6ad8fSAl Viro if (IS_ERR(dentry)) 3465dae6ad8fSAl Viro return PTR_ERR(dentry); 34662ad94ae6SAl Viro 3467dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3468ce3b0f8dSAl Viro mode &= ~current_umask(); 3469dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3470be6d3e56SKentaro Takeda if (error) 3471a8104a9fSAl Viro goto out; 34721da177e4SLinus Torvalds switch (mode & S_IFMT) { 34731da177e4SLinus Torvalds case 0: case S_IFREG: 3474312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34751da177e4SLinus Torvalds break; 34761da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3477dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34781da177e4SLinus Torvalds new_decode_dev(dev)); 34791da177e4SLinus Torvalds break; 34801da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3481dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34821da177e4SLinus Torvalds break; 34831da177e4SLinus Torvalds } 3484a8104a9fSAl Viro out: 3485921a1650SAl Viro done_path_create(&path, dentry); 3486972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3487972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3488972567f1SJeff Layton goto retry; 3489972567f1SJeff Layton } 34901da177e4SLinus Torvalds return error; 34911da177e4SLinus Torvalds } 34921da177e4SLinus Torvalds 34938208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34945590ff0dSUlrich Drepper { 34955590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34965590ff0dSUlrich Drepper } 34975590ff0dSUlrich Drepper 349818bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 34991da177e4SLinus Torvalds { 3500a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35018de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35021da177e4SLinus Torvalds 35031da177e4SLinus Torvalds if (error) 35041da177e4SLinus Torvalds return error; 35051da177e4SLinus Torvalds 3506acfa4380SAl Viro if (!dir->i_op->mkdir) 35071da177e4SLinus Torvalds return -EPERM; 35081da177e4SLinus Torvalds 35091da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35101da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35111da177e4SLinus Torvalds if (error) 35121da177e4SLinus Torvalds return error; 35131da177e4SLinus Torvalds 35148de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35158de52778SAl Viro return -EMLINK; 35168de52778SAl Viro 35171da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3518a74574aaSStephen Smalley if (!error) 3519f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35201da177e4SLinus Torvalds return error; 35211da177e4SLinus Torvalds } 35224d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35231da177e4SLinus Torvalds 3524a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35251da177e4SLinus Torvalds { 35266902d925SDave Hansen struct dentry *dentry; 3527dae6ad8fSAl Viro struct path path; 3528dae6ad8fSAl Viro int error; 3529b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35301da177e4SLinus Torvalds 3531b76d8b82SJeff Layton retry: 3532b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35336902d925SDave Hansen if (IS_ERR(dentry)) 3534dae6ad8fSAl Viro return PTR_ERR(dentry); 35356902d925SDave Hansen 3536dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3537ce3b0f8dSAl Viro mode &= ~current_umask(); 3538dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3539a8104a9fSAl Viro if (!error) 3540dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3541921a1650SAl Viro done_path_create(&path, dentry); 3542b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3543b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3544b76d8b82SJeff Layton goto retry; 3545b76d8b82SJeff Layton } 35461da177e4SLinus Torvalds return error; 35471da177e4SLinus Torvalds } 35481da177e4SLinus Torvalds 3549a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35505590ff0dSUlrich Drepper { 35515590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35525590ff0dSUlrich Drepper } 35535590ff0dSUlrich Drepper 35541da177e4SLinus Torvalds /* 3555a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3556c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3557a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3558a71905f0SSage Weil * then we drop the dentry now. 35591da177e4SLinus Torvalds * 35601da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35611da177e4SLinus Torvalds * do a 35621da177e4SLinus Torvalds * 35631da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35641da177e4SLinus Torvalds * return -EBUSY; 35651da177e4SLinus Torvalds * 35661da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35671da177e4SLinus Torvalds * that is still in use by something else.. 35681da177e4SLinus Torvalds */ 35691da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35701da177e4SLinus Torvalds { 35711da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35721da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 357398474236SWaiman Long if (dentry->d_lockref.count == 1) 35741da177e4SLinus Torvalds __d_drop(dentry); 35751da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35761da177e4SLinus Torvalds } 35774d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 35781da177e4SLinus Torvalds 35791da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35801da177e4SLinus Torvalds { 35811da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35821da177e4SLinus Torvalds 35831da177e4SLinus Torvalds if (error) 35841da177e4SLinus Torvalds return error; 35851da177e4SLinus Torvalds 3586acfa4380SAl Viro if (!dir->i_op->rmdir) 35871da177e4SLinus Torvalds return -EPERM; 35881da177e4SLinus Torvalds 35891d2ef590SAl Viro dget(dentry); 35901b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3591912dbc15SSage Weil 35921da177e4SLinus Torvalds error = -EBUSY; 35937af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3594912dbc15SSage Weil goto out; 3595912dbc15SSage Weil 35961da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3597912dbc15SSage Weil if (error) 3598912dbc15SSage Weil goto out; 3599912dbc15SSage Weil 36003cebde24SSage Weil shrink_dcache_parent(dentry); 36011da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3602912dbc15SSage Weil if (error) 3603912dbc15SSage Weil goto out; 3604912dbc15SSage Weil 36051da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3606d83c49f3SAl Viro dont_mount(dentry); 36078ed936b5SEric W. Biederman detach_mounts(dentry); 36081da177e4SLinus Torvalds 3609912dbc15SSage Weil out: 3610912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36111d2ef590SAl Viro dput(dentry); 3612912dbc15SSage Weil if (!error) 3613912dbc15SSage Weil d_delete(dentry); 36141da177e4SLinus Torvalds return error; 36151da177e4SLinus Torvalds } 36164d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36171da177e4SLinus Torvalds 36185590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36191da177e4SLinus Torvalds { 36201da177e4SLinus Torvalds int error = 0; 362191a27b2aSJeff Layton struct filename *name; 36221da177e4SLinus Torvalds struct dentry *dentry; 36231da177e4SLinus Torvalds struct nameidata nd; 3624c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3625c6ee9206SJeff Layton retry: 3626c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 362791a27b2aSJeff Layton if (IS_ERR(name)) 362891a27b2aSJeff Layton return PTR_ERR(name); 36291da177e4SLinus Torvalds 36301da177e4SLinus Torvalds switch(nd.last_type) { 36311da177e4SLinus Torvalds case LAST_DOTDOT: 36321da177e4SLinus Torvalds error = -ENOTEMPTY; 36331da177e4SLinus Torvalds goto exit1; 36341da177e4SLinus Torvalds case LAST_DOT: 36351da177e4SLinus Torvalds error = -EINVAL; 36361da177e4SLinus Torvalds goto exit1; 36371da177e4SLinus Torvalds case LAST_ROOT: 36381da177e4SLinus Torvalds error = -EBUSY; 36391da177e4SLinus Torvalds goto exit1; 36401da177e4SLinus Torvalds } 36410612d9fbSOGAWA Hirofumi 36420612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3643c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3644c30dabfeSJan Kara if (error) 3645c30dabfeSJan Kara goto exit1; 36460612d9fbSOGAWA Hirofumi 36474ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 364849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36491da177e4SLinus Torvalds error = PTR_ERR(dentry); 36506902d925SDave Hansen if (IS_ERR(dentry)) 36516902d925SDave Hansen goto exit2; 3652e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3653e6bc45d6STheodore Ts'o error = -ENOENT; 3654e6bc45d6STheodore Ts'o goto exit3; 3655e6bc45d6STheodore Ts'o } 3656be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3657be6d3e56SKentaro Takeda if (error) 3658c30dabfeSJan Kara goto exit3; 36594ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 36600622753bSDave Hansen exit3: 36611da177e4SLinus Torvalds dput(dentry); 36626902d925SDave Hansen exit2: 36634ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3664c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 36651da177e4SLinus Torvalds exit1: 36661d957f9bSJan Blunck path_put(&nd.path); 36671da177e4SLinus Torvalds putname(name); 3668c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3669c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3670c6ee9206SJeff Layton goto retry; 3671c6ee9206SJeff Layton } 36721da177e4SLinus Torvalds return error; 36731da177e4SLinus Torvalds } 36741da177e4SLinus Torvalds 36753cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36765590ff0dSUlrich Drepper { 36775590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36785590ff0dSUlrich Drepper } 36795590ff0dSUlrich Drepper 3680b21996e3SJ. Bruce Fields /** 3681b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3682b21996e3SJ. Bruce Fields * @dir: parent directory 3683b21996e3SJ. Bruce Fields * @dentry: victim 3684b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3685b21996e3SJ. Bruce Fields * 3686b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3687b21996e3SJ. Bruce Fields * 3688b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3689b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3690b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3691b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3692b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3693b21996e3SJ. Bruce Fields * 3694b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3695b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3696b21996e3SJ. Bruce Fields * to be NFS exported. 3697b21996e3SJ. Bruce Fields */ 3698b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 36991da177e4SLinus Torvalds { 37009accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37011da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37021da177e4SLinus Torvalds 37031da177e4SLinus Torvalds if (error) 37041da177e4SLinus Torvalds return error; 37051da177e4SLinus Torvalds 3706acfa4380SAl Viro if (!dir->i_op->unlink) 37071da177e4SLinus Torvalds return -EPERM; 37081da177e4SLinus Torvalds 37099accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37108ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37111da177e4SLinus Torvalds error = -EBUSY; 37121da177e4SLinus Torvalds else { 37131da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3714bec1052eSAl Viro if (!error) { 37155a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37165a14696cSJ. Bruce Fields if (error) 3717b21996e3SJ. Bruce Fields goto out; 37181da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37198ed936b5SEric W. Biederman if (!error) { 3720d83c49f3SAl Viro dont_mount(dentry); 37218ed936b5SEric W. Biederman detach_mounts(dentry); 37228ed936b5SEric W. Biederman } 3723bec1052eSAl Viro } 37241da177e4SLinus Torvalds } 3725b21996e3SJ. Bruce Fields out: 37269accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37271da177e4SLinus Torvalds 37281da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37291da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37309accbb97SJ. Bruce Fields fsnotify_link_count(target); 37311da177e4SLinus Torvalds d_delete(dentry); 37321da177e4SLinus Torvalds } 37330eeca283SRobert Love 37341da177e4SLinus Torvalds return error; 37351da177e4SLinus Torvalds } 37364d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37371da177e4SLinus Torvalds 37381da177e4SLinus Torvalds /* 37391da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37401b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37411da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37421da177e4SLinus Torvalds * while waiting on the I/O. 37431da177e4SLinus Torvalds */ 37445590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37451da177e4SLinus Torvalds { 37462ad94ae6SAl Viro int error; 374791a27b2aSJeff Layton struct filename *name; 37481da177e4SLinus Torvalds struct dentry *dentry; 37491da177e4SLinus Torvalds struct nameidata nd; 37501da177e4SLinus Torvalds struct inode *inode = NULL; 3751b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37525d18f813SJeff Layton unsigned int lookup_flags = 0; 37535d18f813SJeff Layton retry: 37545d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 375591a27b2aSJeff Layton if (IS_ERR(name)) 375691a27b2aSJeff Layton return PTR_ERR(name); 37572ad94ae6SAl Viro 37581da177e4SLinus Torvalds error = -EISDIR; 37591da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 37601da177e4SLinus Torvalds goto exit1; 37610612d9fbSOGAWA Hirofumi 37620612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3763c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3764c30dabfeSJan Kara if (error) 3765c30dabfeSJan Kara goto exit1; 3766b21996e3SJ. Bruce Fields retry_deleg: 37674ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 376849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 37691da177e4SLinus Torvalds error = PTR_ERR(dentry); 37701da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37711da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 377250338b88STörök Edwin if (nd.last.name[nd.last.len]) 377350338b88STörök Edwin goto slashes; 37741da177e4SLinus Torvalds inode = dentry->d_inode; 3775b18825a7SDavid Howells if (d_is_negative(dentry)) 3776e6bc45d6STheodore Ts'o goto slashes; 37777de9c6eeSAl Viro ihold(inode); 3778be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3779be6d3e56SKentaro Takeda if (error) 3780c30dabfeSJan Kara goto exit2; 3781b21996e3SJ. Bruce Fields error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); 37821da177e4SLinus Torvalds exit2: 37831da177e4SLinus Torvalds dput(dentry); 37841da177e4SLinus Torvalds } 37854ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 37861da177e4SLinus Torvalds if (inode) 37871da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3788b21996e3SJ. Bruce Fields inode = NULL; 3789b21996e3SJ. Bruce Fields if (delegated_inode) { 37905a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3791b21996e3SJ. Bruce Fields if (!error) 3792b21996e3SJ. Bruce Fields goto retry_deleg; 3793b21996e3SJ. Bruce Fields } 3794c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 37951da177e4SLinus Torvalds exit1: 37961d957f9bSJan Blunck path_put(&nd.path); 37971da177e4SLinus Torvalds putname(name); 37985d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 37995d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38005d18f813SJeff Layton inode = NULL; 38015d18f813SJeff Layton goto retry; 38025d18f813SJeff Layton } 38031da177e4SLinus Torvalds return error; 38041da177e4SLinus Torvalds 38051da177e4SLinus Torvalds slashes: 3806b18825a7SDavid Howells if (d_is_negative(dentry)) 3807b18825a7SDavid Howells error = -ENOENT; 380844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3809b18825a7SDavid Howells error = -EISDIR; 3810b18825a7SDavid Howells else 3811b18825a7SDavid Howells error = -ENOTDIR; 38121da177e4SLinus Torvalds goto exit2; 38131da177e4SLinus Torvalds } 38141da177e4SLinus Torvalds 38152e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38165590ff0dSUlrich Drepper { 38175590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38185590ff0dSUlrich Drepper return -EINVAL; 38195590ff0dSUlrich Drepper 38205590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38215590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38225590ff0dSUlrich Drepper 38235590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38245590ff0dSUlrich Drepper } 38255590ff0dSUlrich Drepper 38263480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38275590ff0dSUlrich Drepper { 38285590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38295590ff0dSUlrich Drepper } 38305590ff0dSUlrich Drepper 3831db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38321da177e4SLinus Torvalds { 3833a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38341da177e4SLinus Torvalds 38351da177e4SLinus Torvalds if (error) 38361da177e4SLinus Torvalds return error; 38371da177e4SLinus Torvalds 3838acfa4380SAl Viro if (!dir->i_op->symlink) 38391da177e4SLinus Torvalds return -EPERM; 38401da177e4SLinus Torvalds 38411da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38421da177e4SLinus Torvalds if (error) 38431da177e4SLinus Torvalds return error; 38441da177e4SLinus Torvalds 38451da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3846a74574aaSStephen Smalley if (!error) 3847f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38481da177e4SLinus Torvalds return error; 38491da177e4SLinus Torvalds } 38504d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38511da177e4SLinus Torvalds 38522e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38532e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38541da177e4SLinus Torvalds { 38552ad94ae6SAl Viro int error; 385691a27b2aSJeff Layton struct filename *from; 38576902d925SDave Hansen struct dentry *dentry; 3858dae6ad8fSAl Viro struct path path; 3859f46d3567SJeff Layton unsigned int lookup_flags = 0; 38601da177e4SLinus Torvalds 38611da177e4SLinus Torvalds from = getname(oldname); 38621da177e4SLinus Torvalds if (IS_ERR(from)) 38631da177e4SLinus Torvalds return PTR_ERR(from); 3864f46d3567SJeff Layton retry: 3865f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 38661da177e4SLinus Torvalds error = PTR_ERR(dentry); 38676902d925SDave Hansen if (IS_ERR(dentry)) 3868dae6ad8fSAl Viro goto out_putname; 38696902d925SDave Hansen 387091a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3871a8104a9fSAl Viro if (!error) 387291a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3873921a1650SAl Viro done_path_create(&path, dentry); 3874f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3875f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3876f46d3567SJeff Layton goto retry; 3877f46d3567SJeff Layton } 38786902d925SDave Hansen out_putname: 38791da177e4SLinus Torvalds putname(from); 38801da177e4SLinus Torvalds return error; 38811da177e4SLinus Torvalds } 38821da177e4SLinus Torvalds 38833480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 38845590ff0dSUlrich Drepper { 38855590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 38865590ff0dSUlrich Drepper } 38875590ff0dSUlrich Drepper 3888146a8595SJ. Bruce Fields /** 3889146a8595SJ. Bruce Fields * vfs_link - create a new link 3890146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3891146a8595SJ. Bruce Fields * @dir: new parent 3892146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3893146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3894146a8595SJ. Bruce Fields * 3895146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3896146a8595SJ. Bruce Fields * 3897146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3898146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3899146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3900146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3901146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3902146a8595SJ. Bruce Fields * 3903146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3904146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3905146a8595SJ. Bruce Fields * to be NFS exported. 3906146a8595SJ. Bruce Fields */ 3907146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39081da177e4SLinus Torvalds { 39091da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39108de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39111da177e4SLinus Torvalds int error; 39121da177e4SLinus Torvalds 39131da177e4SLinus Torvalds if (!inode) 39141da177e4SLinus Torvalds return -ENOENT; 39151da177e4SLinus Torvalds 3916a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39171da177e4SLinus Torvalds if (error) 39181da177e4SLinus Torvalds return error; 39191da177e4SLinus Torvalds 39201da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39211da177e4SLinus Torvalds return -EXDEV; 39221da177e4SLinus Torvalds 39231da177e4SLinus Torvalds /* 39241da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39251da177e4SLinus Torvalds */ 39261da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39271da177e4SLinus Torvalds return -EPERM; 3928acfa4380SAl Viro if (!dir->i_op->link) 39291da177e4SLinus Torvalds return -EPERM; 39307e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39311da177e4SLinus Torvalds return -EPERM; 39321da177e4SLinus Torvalds 39331da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39341da177e4SLinus Torvalds if (error) 39351da177e4SLinus Torvalds return error; 39361da177e4SLinus Torvalds 39377e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3938aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3939f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3940aae8a97dSAneesh Kumar K.V error = -ENOENT; 39418de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39428de52778SAl Viro error = -EMLINK; 3943146a8595SJ. Bruce Fields else { 3944146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3945146a8595SJ. Bruce Fields if (!error) 39461da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3947146a8595SJ. Bruce Fields } 3948f4e0c30cSAl Viro 3949f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3950f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3951f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3952f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3953f4e0c30cSAl Viro } 39547e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3955e31e14ecSStephen Smalley if (!error) 39567e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39571da177e4SLinus Torvalds return error; 39581da177e4SLinus Torvalds } 39594d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39601da177e4SLinus Torvalds 39611da177e4SLinus Torvalds /* 39621da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39631da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 39641da177e4SLinus Torvalds * newname. --KAB 39651da177e4SLinus Torvalds * 39661da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 39671da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 39681da177e4SLinus Torvalds * and other special files. --ADM 39691da177e4SLinus Torvalds */ 39702e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 39712e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 39721da177e4SLinus Torvalds { 39731da177e4SLinus Torvalds struct dentry *new_dentry; 3974dae6ad8fSAl Viro struct path old_path, new_path; 3975146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 397611a7b371SAneesh Kumar K.V int how = 0; 39771da177e4SLinus Torvalds int error; 39781da177e4SLinus Torvalds 397911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3980c04030e1SUlrich Drepper return -EINVAL; 398111a7b371SAneesh Kumar K.V /* 3982f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3983f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3984f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 398511a7b371SAneesh Kumar K.V */ 3986f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3987f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3988f0cc6ffbSLinus Torvalds return -ENOENT; 398911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3990f0cc6ffbSLinus Torvalds } 3991c04030e1SUlrich Drepper 399211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 399311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 3994442e31caSJeff Layton retry: 399511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 39961da177e4SLinus Torvalds if (error) 39972ad94ae6SAl Viro return error; 39982ad94ae6SAl Viro 3999442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4000442e31caSJeff Layton (how & LOOKUP_REVAL)); 40011da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40026902d925SDave Hansen if (IS_ERR(new_dentry)) 4003dae6ad8fSAl Viro goto out; 4004dae6ad8fSAl Viro 4005dae6ad8fSAl Viro error = -EXDEV; 4006dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4007dae6ad8fSAl Viro goto out_dput; 4008800179c9SKees Cook error = may_linkat(&old_path); 4009800179c9SKees Cook if (unlikely(error)) 4010800179c9SKees Cook goto out_dput; 4011dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4012be6d3e56SKentaro Takeda if (error) 4013a8104a9fSAl Viro goto out_dput; 4014146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 401575c3f29dSDave Hansen out_dput: 4016921a1650SAl Viro done_path_create(&new_path, new_dentry); 4017146a8595SJ. Bruce Fields if (delegated_inode) { 4018146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4019d22e6338SOleg Drokin if (!error) { 4020d22e6338SOleg Drokin path_put(&old_path); 4021146a8595SJ. Bruce Fields goto retry; 4022146a8595SJ. Bruce Fields } 4023d22e6338SOleg Drokin } 4024442e31caSJeff Layton if (retry_estale(error, how)) { 4025d22e6338SOleg Drokin path_put(&old_path); 4026442e31caSJeff Layton how |= LOOKUP_REVAL; 4027442e31caSJeff Layton goto retry; 4028442e31caSJeff Layton } 40291da177e4SLinus Torvalds out: 40302d8f3038SAl Viro path_put(&old_path); 40311da177e4SLinus Torvalds 40321da177e4SLinus Torvalds return error; 40331da177e4SLinus Torvalds } 40341da177e4SLinus Torvalds 40353480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40365590ff0dSUlrich Drepper { 4037c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40385590ff0dSUlrich Drepper } 40395590ff0dSUlrich Drepper 4040bc27027aSMiklos Szeredi /** 4041bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4042bc27027aSMiklos Szeredi * @old_dir: parent of source 4043bc27027aSMiklos Szeredi * @old_dentry: source 4044bc27027aSMiklos Szeredi * @new_dir: parent of destination 4045bc27027aSMiklos Szeredi * @new_dentry: destination 4046bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4047520c8b16SMiklos Szeredi * @flags: rename flags 4048bc27027aSMiklos Szeredi * 4049bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4050bc27027aSMiklos Szeredi * 4051bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4052bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4053bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4054bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4055bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4056bc27027aSMiklos Szeredi * so. 4057bc27027aSMiklos Szeredi * 4058bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4059bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4060bc27027aSMiklos Szeredi * to be NFS exported. 4061bc27027aSMiklos Szeredi * 40621da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40631da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 40641da177e4SLinus Torvalds * Problems: 4065d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 40661da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 40671da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4068a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 40691da177e4SLinus Torvalds * story. 40706cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 40716cedba89SJ. Bruce Fields * and source (if it is not a directory). 40721b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 40731da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 40741da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4075a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 40761da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 40771da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 40781da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4079a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 40801da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 40811da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 40821da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4083e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 40841b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 40851da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4086c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 40871da177e4SLinus Torvalds * locking]. 40881da177e4SLinus Torvalds */ 40891da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40908e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4091520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 40921da177e4SLinus Torvalds { 40931da177e4SLinus Torvalds int error; 4094bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 409559b0df21SEric Paris const unsigned char *old_name; 4096bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4097bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4098da1ce067SMiklos Szeredi bool new_is_dir = false; 4099da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41001da177e4SLinus Torvalds 4101bc27027aSMiklos Szeredi if (source == target) 41021da177e4SLinus Torvalds return 0; 41031da177e4SLinus Torvalds 41041da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41051da177e4SLinus Torvalds if (error) 41061da177e4SLinus Torvalds return error; 41071da177e4SLinus Torvalds 4108da1ce067SMiklos Szeredi if (!target) { 4109a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4110da1ce067SMiklos Szeredi } else { 4111da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4112da1ce067SMiklos Szeredi 4113da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41141da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4115da1ce067SMiklos Szeredi else 4116da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4117da1ce067SMiklos Szeredi } 41181da177e4SLinus Torvalds if (error) 41191da177e4SLinus Torvalds return error; 41201da177e4SLinus Torvalds 41217177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41221da177e4SLinus Torvalds return -EPERM; 41231da177e4SLinus Torvalds 4124520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4125520c8b16SMiklos Szeredi return -EINVAL; 4126520c8b16SMiklos Szeredi 4127bc27027aSMiklos Szeredi /* 4128bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4129bc27027aSMiklos Szeredi * we'll need to flip '..'. 4130bc27027aSMiklos Szeredi */ 4131da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4132da1ce067SMiklos Szeredi if (is_dir) { 4133bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4134bc27027aSMiklos Szeredi if (error) 4135bc27027aSMiklos Szeredi return error; 4136bc27027aSMiklos Szeredi } 4137da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4138da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4139da1ce067SMiklos Szeredi if (error) 4140da1ce067SMiklos Szeredi return error; 4141da1ce067SMiklos Szeredi } 4142da1ce067SMiklos Szeredi } 41430eeca283SRobert Love 41440b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41450b3974ebSMiklos Szeredi flags); 4146bc27027aSMiklos Szeredi if (error) 4147bc27027aSMiklos Szeredi return error; 4148bc27027aSMiklos Szeredi 4149bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4150bc27027aSMiklos Szeredi dget(new_dentry); 4151da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4152bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4153bc27027aSMiklos Szeredi else if (target) 4154bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4155bc27027aSMiklos Szeredi 4156bc27027aSMiklos Szeredi error = -EBUSY; 41577af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4158bc27027aSMiklos Szeredi goto out; 4159bc27027aSMiklos Szeredi 4160da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4161bc27027aSMiklos Szeredi error = -EMLINK; 4162da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4163bc27027aSMiklos Szeredi goto out; 4164da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4165da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4166da1ce067SMiklos Szeredi goto out; 4167da1ce067SMiklos Szeredi } 4168da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4169bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4170da1ce067SMiklos Szeredi if (!is_dir) { 4171bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4172bc27027aSMiklos Szeredi if (error) 4173bc27027aSMiklos Szeredi goto out; 4174da1ce067SMiklos Szeredi } 4175da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4176bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4177bc27027aSMiklos Szeredi if (error) 4178bc27027aSMiklos Szeredi goto out; 4179bc27027aSMiklos Szeredi } 41807177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4181520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4182520c8b16SMiklos Szeredi new_dir, new_dentry); 4183520c8b16SMiklos Szeredi } else { 41847177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4185520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4186520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4187520c8b16SMiklos Szeredi } 4188bc27027aSMiklos Szeredi if (error) 4189bc27027aSMiklos Szeredi goto out; 4190bc27027aSMiklos Szeredi 4191da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 41921da177e4SLinus Torvalds if (is_dir) 4193bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4194bc27027aSMiklos Szeredi dont_mount(new_dentry); 41958ed936b5SEric W. Biederman detach_mounts(new_dentry); 4196bc27027aSMiklos Szeredi } 4197da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4198da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4199bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4200da1ce067SMiklos Szeredi else 4201da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4202da1ce067SMiklos Szeredi } 4203bc27027aSMiklos Szeredi out: 4204da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4205bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4206bc27027aSMiklos Szeredi else if (target) 4207bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4208bc27027aSMiklos Szeredi dput(new_dentry); 4209da1ce067SMiklos Szeredi if (!error) { 4210123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4211da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4212da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4213da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4214da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4215da1ce067SMiklos Szeredi } 4216da1ce067SMiklos Szeredi } 42170eeca283SRobert Love fsnotify_oldname_free(old_name); 42180eeca283SRobert Love 42191da177e4SLinus Torvalds return error; 42201da177e4SLinus Torvalds } 42214d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42221da177e4SLinus Torvalds 4223520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4224520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42251da177e4SLinus Torvalds { 42261da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 42271da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42281da177e4SLinus Torvalds struct dentry *trap; 42291da177e4SLinus Torvalds struct nameidata oldnd, newnd; 42308e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 423191a27b2aSJeff Layton struct filename *from; 423291a27b2aSJeff Layton struct filename *to; 4233c6a94284SJeff Layton unsigned int lookup_flags = 0; 4234c6a94284SJeff Layton bool should_retry = false; 42352ad94ae6SAl Viro int error; 4236520c8b16SMiklos Szeredi 42370d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4238da1ce067SMiklos Szeredi return -EINVAL; 4239da1ce067SMiklos Szeredi 42400d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42410d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4242520c8b16SMiklos Szeredi return -EINVAL; 4243520c8b16SMiklos Szeredi 42440d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42450d7a8555SMiklos Szeredi return -EPERM; 42460d7a8555SMiklos Szeredi 4247c6a94284SJeff Layton retry: 4248c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 424991a27b2aSJeff Layton if (IS_ERR(from)) { 425091a27b2aSJeff Layton error = PTR_ERR(from); 42511da177e4SLinus Torvalds goto exit; 425291a27b2aSJeff Layton } 42531da177e4SLinus Torvalds 4254c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 425591a27b2aSJeff Layton if (IS_ERR(to)) { 425691a27b2aSJeff Layton error = PTR_ERR(to); 42571da177e4SLinus Torvalds goto exit1; 425891a27b2aSJeff Layton } 42591da177e4SLinus Torvalds 42601da177e4SLinus Torvalds error = -EXDEV; 42614ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 42621da177e4SLinus Torvalds goto exit2; 42631da177e4SLinus Torvalds 42644ac91378SJan Blunck old_dir = oldnd.path.dentry; 42651da177e4SLinus Torvalds error = -EBUSY; 42661da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 42671da177e4SLinus Torvalds goto exit2; 42681da177e4SLinus Torvalds 42694ac91378SJan Blunck new_dir = newnd.path.dentry; 42700a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 42710a7c3937SMiklos Szeredi error = -EEXIST; 42721da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 42731da177e4SLinus Torvalds goto exit2; 42741da177e4SLinus Torvalds 4275c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4276c30dabfeSJan Kara if (error) 4277c30dabfeSJan Kara goto exit2; 4278c30dabfeSJan Kara 42790612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 42800612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 4281da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42824e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 42830612d9fbSOGAWA Hirofumi 42848e6d782cSJ. Bruce Fields retry_deleg: 42851da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 42861da177e4SLinus Torvalds 428749705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 42881da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 42891da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 42901da177e4SLinus Torvalds goto exit3; 42911da177e4SLinus Torvalds /* source must exist */ 42921da177e4SLinus Torvalds error = -ENOENT; 4293b18825a7SDavid Howells if (d_is_negative(old_dentry)) 42941da177e4SLinus Torvalds goto exit4; 429549705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 42961da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42971da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 42981da177e4SLinus Torvalds goto exit4; 42990a7c3937SMiklos Szeredi error = -EEXIST; 43000a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43010a7c3937SMiklos Szeredi goto exit5; 4302da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4303da1ce067SMiklos Szeredi error = -ENOENT; 4304da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4305da1ce067SMiklos Szeredi goto exit5; 4306da1ce067SMiklos Szeredi 4307da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4308da1ce067SMiklos Szeredi error = -ENOTDIR; 4309da1ce067SMiklos Szeredi if (newnd.last.name[newnd.last.len]) 4310da1ce067SMiklos Szeredi goto exit5; 4311da1ce067SMiklos Szeredi } 4312da1ce067SMiklos Szeredi } 43130a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43140a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43150a7c3937SMiklos Szeredi error = -ENOTDIR; 43160a7c3937SMiklos Szeredi if (oldnd.last.name[oldnd.last.len]) 43170a7c3937SMiklos Szeredi goto exit5; 4318da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) 43190a7c3937SMiklos Szeredi goto exit5; 43200a7c3937SMiklos Szeredi } 43210a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43220a7c3937SMiklos Szeredi error = -EINVAL; 43230a7c3937SMiklos Szeredi if (old_dentry == trap) 43240a7c3937SMiklos Szeredi goto exit5; 43251da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4326da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43271da177e4SLinus Torvalds error = -ENOTEMPTY; 43281da177e4SLinus Torvalds if (new_dentry == trap) 43291da177e4SLinus Torvalds goto exit5; 43301da177e4SLinus Torvalds 4331be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 43320b3974ebSMiklos Szeredi &newnd.path, new_dentry, flags); 4333be6d3e56SKentaro Takeda if (error) 4334c30dabfeSJan Kara goto exit5; 43351da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 43368e6d782cSJ. Bruce Fields new_dir->d_inode, new_dentry, 4337520c8b16SMiklos Szeredi &delegated_inode, flags); 43381da177e4SLinus Torvalds exit5: 43391da177e4SLinus Torvalds dput(new_dentry); 43401da177e4SLinus Torvalds exit4: 43411da177e4SLinus Torvalds dput(old_dentry); 43421da177e4SLinus Torvalds exit3: 43431da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 43448e6d782cSJ. Bruce Fields if (delegated_inode) { 43458e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43468e6d782cSJ. Bruce Fields if (!error) 43478e6d782cSJ. Bruce Fields goto retry_deleg; 43488e6d782cSJ. Bruce Fields } 4349c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 43501da177e4SLinus Torvalds exit2: 4351c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4352c6a94284SJeff Layton should_retry = true; 43531d957f9bSJan Blunck path_put(&newnd.path); 43542ad94ae6SAl Viro putname(to); 43551da177e4SLinus Torvalds exit1: 43561d957f9bSJan Blunck path_put(&oldnd.path); 43571da177e4SLinus Torvalds putname(from); 4358c6a94284SJeff Layton if (should_retry) { 4359c6a94284SJeff Layton should_retry = false; 4360c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4361c6a94284SJeff Layton goto retry; 4362c6a94284SJeff Layton } 43632ad94ae6SAl Viro exit: 43641da177e4SLinus Torvalds return error; 43651da177e4SLinus Torvalds } 43661da177e4SLinus Torvalds 4367520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4368520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4369520c8b16SMiklos Szeredi { 4370520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4371520c8b16SMiklos Szeredi } 4372520c8b16SMiklos Szeredi 4373a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 43745590ff0dSUlrich Drepper { 4375520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43765590ff0dSUlrich Drepper } 43775590ff0dSUlrich Drepper 4378787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4379787fb6bcSMiklos Szeredi { 4380787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4381787fb6bcSMiklos Szeredi if (error) 4382787fb6bcSMiklos Szeredi return error; 4383787fb6bcSMiklos Szeredi 4384787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4385787fb6bcSMiklos Szeredi return -EPERM; 4386787fb6bcSMiklos Szeredi 4387787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4388787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4389787fb6bcSMiklos Szeredi } 4390787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4391787fb6bcSMiklos Szeredi 43925d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 43931da177e4SLinus Torvalds { 43945d826c84SAl Viro int len = PTR_ERR(link); 43951da177e4SLinus Torvalds if (IS_ERR(link)) 43961da177e4SLinus Torvalds goto out; 43971da177e4SLinus Torvalds 43981da177e4SLinus Torvalds len = strlen(link); 43991da177e4SLinus Torvalds if (len > (unsigned) buflen) 44001da177e4SLinus Torvalds len = buflen; 44011da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44021da177e4SLinus Torvalds len = -EFAULT; 44031da177e4SLinus Torvalds out: 44041da177e4SLinus Torvalds return len; 44051da177e4SLinus Torvalds } 44065d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44071da177e4SLinus Torvalds 44081da177e4SLinus Torvalds /* 44091da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44101da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44111da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44121da177e4SLinus Torvalds */ 44131da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44141da177e4SLinus Torvalds { 44151da177e4SLinus Torvalds struct nameidata nd; 4416cc314eefSLinus Torvalds void *cookie; 4417694a1764SMarcin Slusarz int res; 4418cc314eefSLinus Torvalds 44191da177e4SLinus Torvalds nd.depth = 0; 4420cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4421694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4422694a1764SMarcin Slusarz return PTR_ERR(cookie); 4423694a1764SMarcin Slusarz 44245d826c84SAl Viro res = readlink_copy(buffer, buflen, nd_get_link(&nd)); 44251da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4426cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4427694a1764SMarcin Slusarz return res; 44281da177e4SLinus Torvalds } 44294d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44301da177e4SLinus Torvalds 44311da177e4SLinus Torvalds /* get the link contents into pagecache */ 44321da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44331da177e4SLinus Torvalds { 4434ebd09abbSDuane Griffin char *kaddr; 44351da177e4SLinus Torvalds struct page *page; 44361da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4437090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44381da177e4SLinus Torvalds if (IS_ERR(page)) 44396fe6900eSNick Piggin return (char*)page; 44401da177e4SLinus Torvalds *ppage = page; 4441ebd09abbSDuane Griffin kaddr = kmap(page); 4442ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4443ebd09abbSDuane Griffin return kaddr; 44441da177e4SLinus Torvalds } 44451da177e4SLinus Torvalds 44461da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44471da177e4SLinus Torvalds { 44481da177e4SLinus Torvalds struct page *page = NULL; 44495d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44501da177e4SLinus Torvalds if (page) { 44511da177e4SLinus Torvalds kunmap(page); 44521da177e4SLinus Torvalds page_cache_release(page); 44531da177e4SLinus Torvalds } 44541da177e4SLinus Torvalds return res; 44551da177e4SLinus Torvalds } 44564d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44571da177e4SLinus Torvalds 4458cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 44591da177e4SLinus Torvalds { 4460cc314eefSLinus Torvalds struct page *page = NULL; 44611da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4462cc314eefSLinus Torvalds return page; 44631da177e4SLinus Torvalds } 44644d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 44651da177e4SLinus Torvalds 4466cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 44671da177e4SLinus Torvalds { 4468cc314eefSLinus Torvalds struct page *page = cookie; 4469cc314eefSLinus Torvalds 4470cc314eefSLinus Torvalds if (page) { 44711da177e4SLinus Torvalds kunmap(page); 44721da177e4SLinus Torvalds page_cache_release(page); 44731da177e4SLinus Torvalds } 44741da177e4SLinus Torvalds } 44754d359507SAl Viro EXPORT_SYMBOL(page_put_link); 44761da177e4SLinus Torvalds 447754566b2cSNick Piggin /* 447854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 447954566b2cSNick Piggin */ 448054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 44811da177e4SLinus Torvalds { 44821da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 44830adb25d2SKirill Korotaev struct page *page; 4484afddba49SNick Piggin void *fsdata; 4485beb497abSDmitriy Monakhov int err; 44861da177e4SLinus Torvalds char *kaddr; 448754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 448854566b2cSNick Piggin if (nofs) 448954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 44901da177e4SLinus Torvalds 44917e53cac4SNeilBrown retry: 4492afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 449354566b2cSNick Piggin flags, &page, &fsdata); 44941da177e4SLinus Torvalds if (err) 4495afddba49SNick Piggin goto fail; 4496afddba49SNick Piggin 4497e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 44981da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4499e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4500afddba49SNick Piggin 4501afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4502afddba49SNick Piggin page, fsdata); 45031da177e4SLinus Torvalds if (err < 0) 45041da177e4SLinus Torvalds goto fail; 4505afddba49SNick Piggin if (err < len-1) 4506afddba49SNick Piggin goto retry; 4507afddba49SNick Piggin 45081da177e4SLinus Torvalds mark_inode_dirty(inode); 45091da177e4SLinus Torvalds return 0; 45101da177e4SLinus Torvalds fail: 45111da177e4SLinus Torvalds return err; 45121da177e4SLinus Torvalds } 45134d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45141da177e4SLinus Torvalds 45150adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45160adb25d2SKirill Korotaev { 45170adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 451854566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45190adb25d2SKirill Korotaev } 45204d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45210adb25d2SKirill Korotaev 452292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45231da177e4SLinus Torvalds .readlink = generic_readlink, 45241da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45251da177e4SLinus Torvalds .put_link = page_put_link, 45261da177e4SLinus Torvalds }; 45271da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4528