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 } 4191da177e4SLinus Torvalds 420f4d6ff89SAl Viro /** 4210bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4220bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42355852635SRandy Dunlap * @inode: Inode to check permission on 4240bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4250bdaea90SDavid Howells * 4260bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4270bdaea90SDavid Howells */ 4280bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4290bdaea90SDavid Howells { 4300bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4310bdaea90SDavid Howells umode_t mode = inode->i_mode; 4320bdaea90SDavid Howells 4330bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4340bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4350bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4360bdaea90SDavid Howells return -EROFS; 4370bdaea90SDavid Howells } 4380bdaea90SDavid Howells return 0; 4390bdaea90SDavid Howells } 4400bdaea90SDavid Howells 4410bdaea90SDavid Howells /** 4420bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4430bdaea90SDavid Howells * @inode: Inode to check permission on 4440bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4450bdaea90SDavid Howells * 4460bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4470bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4480bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4490bdaea90SDavid Howells * 4500bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4510bdaea90SDavid Howells */ 4520bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4530bdaea90SDavid Howells { 4540bdaea90SDavid Howells int retval; 4550bdaea90SDavid Howells 4560bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4570bdaea90SDavid Howells if (retval) 4580bdaea90SDavid Howells return retval; 4590bdaea90SDavid Howells return __inode_permission(inode, mask); 4600bdaea90SDavid Howells } 4614d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4620bdaea90SDavid Howells 4630bdaea90SDavid Howells /** 4645dd784d0SJan Blunck * path_get - get a reference to a path 4655dd784d0SJan Blunck * @path: path to get the reference to 4665dd784d0SJan Blunck * 4675dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4685dd784d0SJan Blunck */ 469dcf787f3SAl Viro void path_get(const struct path *path) 4705dd784d0SJan Blunck { 4715dd784d0SJan Blunck mntget(path->mnt); 4725dd784d0SJan Blunck dget(path->dentry); 4735dd784d0SJan Blunck } 4745dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4755dd784d0SJan Blunck 4765dd784d0SJan Blunck /** 4771d957f9bSJan Blunck * path_put - put a reference to a path 4781d957f9bSJan Blunck * @path: path to put the reference to 4791d957f9bSJan Blunck * 4801d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4811d957f9bSJan Blunck */ 482dcf787f3SAl Viro void path_put(const struct path *path) 4831da177e4SLinus Torvalds { 4841d957f9bSJan Blunck dput(path->dentry); 4851d957f9bSJan Blunck mntput(path->mnt); 4861da177e4SLinus Torvalds } 4871d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4881da177e4SLinus Torvalds 48919660af7SAl Viro /* 49031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 49119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 49219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 49319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 49419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 49519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 49619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 49719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 49831e6b01fSNick Piggin */ 49931e6b01fSNick Piggin 50031e6b01fSNick Piggin /** 50119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 50219660af7SAl Viro * @nd: nameidata pathwalk data 50319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 50439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 50531e6b01fSNick Piggin * 50619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 50719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 50819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 50931e6b01fSNick Piggin */ 51019660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 51131e6b01fSNick Piggin { 51231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 51331e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 51431e6b01fSNick Piggin 51531e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 516e5c832d5SLinus Torvalds 517e5c832d5SLinus Torvalds /* 51848a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 51948a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 52048a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 52148a066e7SAl Viro * before returning. Do vfsmount first; if dentry 52248a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 52348a066e7SAl Viro * and rely on dput(NULL) being a no-op. 524e5c832d5SLinus Torvalds */ 52548a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 526e5c832d5SLinus Torvalds return -ECHILD; 527e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 52815570086SLinus Torvalds 52948a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 53048a066e7SAl Viro nd->path.dentry = NULL; 531d870b4a1SAl Viro goto out; 53248a066e7SAl Viro } 53348a066e7SAl Viro 53415570086SLinus Torvalds /* 53515570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 53615570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 53715570086SLinus Torvalds * 53815570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 53915570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 54015570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 54115570086SLinus Torvalds * since we checked the sequence number of the parent after we got 54215570086SLinus Torvalds * the child sequence number. So we know the parent must still 54315570086SLinus Torvalds * be valid if the child sequence number is still valid. 54415570086SLinus Torvalds */ 54519660af7SAl Viro if (!dentry) { 546e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 547e5c832d5SLinus Torvalds goto out; 54819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 54919660af7SAl Viro } else { 550e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 551e5c832d5SLinus Torvalds goto out; 552e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 553e5c832d5SLinus Torvalds goto drop_dentry; 55419660af7SAl Viro } 555e5c832d5SLinus Torvalds 556e5c832d5SLinus Torvalds /* 557e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 558e5c832d5SLinus Torvalds * still valid and get it if required. 559e5c832d5SLinus Torvalds */ 560e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 561e5c832d5SLinus Torvalds spin_lock(&fs->lock); 562e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 563e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 56431e6b01fSNick Piggin path_get(&nd->root); 56531e6b01fSNick Piggin spin_unlock(&fs->lock); 56631e6b01fSNick Piggin } 56731e6b01fSNick Piggin 5688b61e74fSAl Viro rcu_read_unlock(); 56931e6b01fSNick Piggin return 0; 57019660af7SAl Viro 571e5c832d5SLinus Torvalds unlock_and_drop_dentry: 57231e6b01fSNick Piggin spin_unlock(&fs->lock); 573e5c832d5SLinus Torvalds drop_dentry: 5748b61e74fSAl Viro rcu_read_unlock(); 575e5c832d5SLinus Torvalds dput(dentry); 576d0d27277SLinus Torvalds goto drop_root_mnt; 577e5c832d5SLinus Torvalds out: 5788b61e74fSAl Viro rcu_read_unlock(); 579d0d27277SLinus Torvalds drop_root_mnt: 580d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 581d0d27277SLinus Torvalds nd->root.mnt = NULL; 58231e6b01fSNick Piggin return -ECHILD; 58331e6b01fSNick Piggin } 58431e6b01fSNick Piggin 5854ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 58634286d66SNick Piggin { 5874ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 58834286d66SNick Piggin } 58934286d66SNick Piggin 5909f1fafeeSAl Viro /** 5919f1fafeeSAl Viro * complete_walk - successful completion of path walk 5929f1fafeeSAl Viro * @nd: pointer nameidata 59339159de2SJeff Layton * 5949f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5959f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5969f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5979f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5989f1fafeeSAl Viro * need to drop nd->path. 59939159de2SJeff Layton */ 6009f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 60139159de2SJeff Layton { 60216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 60339159de2SJeff Layton int status; 60439159de2SJeff Layton 6059f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6069f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6079f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6089f1fafeeSAl Viro nd->root.mnt = NULL; 60915570086SLinus Torvalds 61048a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6118b61e74fSAl Viro rcu_read_unlock(); 61248a066e7SAl Viro return -ECHILD; 61348a066e7SAl Viro } 614e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6158b61e74fSAl Viro rcu_read_unlock(); 61648a066e7SAl Viro mntput(nd->path.mnt); 6179f1fafeeSAl Viro return -ECHILD; 6189f1fafeeSAl Viro } 619e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6208b61e74fSAl Viro rcu_read_unlock(); 621e5c832d5SLinus Torvalds dput(dentry); 62248a066e7SAl Viro mntput(nd->path.mnt); 623e5c832d5SLinus Torvalds return -ECHILD; 624e5c832d5SLinus Torvalds } 6258b61e74fSAl Viro rcu_read_unlock(); 6269f1fafeeSAl Viro } 6279f1fafeeSAl Viro 62816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 62939159de2SJeff Layton return 0; 63039159de2SJeff Layton 631ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 63216c2cd71SAl Viro return 0; 63316c2cd71SAl Viro 634ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 63539159de2SJeff Layton if (status > 0) 63639159de2SJeff Layton return 0; 63739159de2SJeff Layton 63816c2cd71SAl Viro if (!status) 63939159de2SJeff Layton status = -ESTALE; 64016c2cd71SAl Viro 6419f1fafeeSAl Viro path_put(&nd->path); 64239159de2SJeff Layton return status; 64339159de2SJeff Layton } 64439159de2SJeff Layton 6452a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6462a737871SAl Viro { 647f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6482a737871SAl Viro } 6492a737871SAl Viro 6506de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6516de88d72SAl Viro 6527bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 65331e6b01fSNick Piggin { 65431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6557bd88377SAl Viro unsigned seq, res; 656c28cc364SNick Piggin 657c28cc364SNick Piggin do { 658c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 65931e6b01fSNick Piggin nd->root = fs->root; 6607bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 661c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6627bd88377SAl Viro return res; 66331e6b01fSNick Piggin } 66431e6b01fSNick Piggin 6651d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 666051d3812SIan Kent { 667051d3812SIan Kent dput(path->dentry); 6684ac91378SJan Blunck if (path->mnt != nd->path.mnt) 669051d3812SIan Kent mntput(path->mnt); 670051d3812SIan Kent } 671051d3812SIan Kent 6727b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6737b9337aaSNick Piggin struct nameidata *nd) 674051d3812SIan Kent { 67531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6764ac91378SJan Blunck dput(nd->path.dentry); 67731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6784ac91378SJan Blunck mntput(nd->path.mnt); 6799a229683SHuang Shijie } 68031e6b01fSNick Piggin nd->path.mnt = path->mnt; 6814ac91378SJan Blunck nd->path.dentry = path->dentry; 682051d3812SIan Kent } 683051d3812SIan Kent 684b5fb63c1SChristoph Hellwig /* 685b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 686b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 687b5fb63c1SChristoph Hellwig */ 688b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 689b5fb63c1SChristoph Hellwig { 690b5fb63c1SChristoph Hellwig path_put(&nd->path); 691b5fb63c1SChristoph Hellwig 692b5fb63c1SChristoph Hellwig nd->path = *path; 693b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 694b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 695b5fb63c1SChristoph Hellwig } 696b5fb63c1SChristoph Hellwig 697574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 698574197e0SAl Viro { 699574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 7006d7b5aaeSAl Viro if (inode->i_op->put_link) 701574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 702574197e0SAl Viro path_put(link); 703574197e0SAl Viro } 704574197e0SAl Viro 705561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 706561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 707800179c9SKees Cook 708800179c9SKees Cook /** 709800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 710800179c9SKees Cook * @link: The path of the symlink 71155852635SRandy Dunlap * @nd: nameidata pathwalk data 712800179c9SKees Cook * 713800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 714800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 715800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 716800179c9SKees Cook * processes from failing races against path names that may change out 717800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 718800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 719800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 720800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 721800179c9SKees Cook * 722800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 723800179c9SKees Cook */ 724800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 725800179c9SKees Cook { 726800179c9SKees Cook const struct inode *inode; 727800179c9SKees Cook const struct inode *parent; 728800179c9SKees Cook 729800179c9SKees Cook if (!sysctl_protected_symlinks) 730800179c9SKees Cook return 0; 731800179c9SKees Cook 732800179c9SKees Cook /* Allowed if owner and follower match. */ 733800179c9SKees Cook inode = link->dentry->d_inode; 73481abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 735800179c9SKees Cook return 0; 736800179c9SKees Cook 737800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 738800179c9SKees Cook parent = nd->path.dentry->d_inode; 739800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 740800179c9SKees Cook return 0; 741800179c9SKees Cook 742800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 74381abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 744800179c9SKees Cook return 0; 745800179c9SKees Cook 746ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 747800179c9SKees Cook path_put_conditional(link, nd); 748800179c9SKees Cook path_put(&nd->path); 749800179c9SKees Cook return -EACCES; 750800179c9SKees Cook } 751800179c9SKees Cook 752800179c9SKees Cook /** 753800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 754800179c9SKees Cook * @inode: the source inode to hardlink from 755800179c9SKees Cook * 756800179c9SKees Cook * Return false if at least one of the following conditions: 757800179c9SKees Cook * - inode is not a regular file 758800179c9SKees Cook * - inode is setuid 759800179c9SKees Cook * - inode is setgid and group-exec 760800179c9SKees Cook * - access failure for read and write 761800179c9SKees Cook * 762800179c9SKees Cook * Otherwise returns true. 763800179c9SKees Cook */ 764800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 765800179c9SKees Cook { 766800179c9SKees Cook umode_t mode = inode->i_mode; 767800179c9SKees Cook 768800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 769800179c9SKees Cook if (!S_ISREG(mode)) 770800179c9SKees Cook return false; 771800179c9SKees Cook 772800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 773800179c9SKees Cook if (mode & S_ISUID) 774800179c9SKees Cook return false; 775800179c9SKees Cook 776800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 777800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 778800179c9SKees Cook return false; 779800179c9SKees Cook 780800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 781800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 782800179c9SKees Cook return false; 783800179c9SKees Cook 784800179c9SKees Cook return true; 785800179c9SKees Cook } 786800179c9SKees Cook 787800179c9SKees Cook /** 788800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 789800179c9SKees Cook * @link: the source to hardlink from 790800179c9SKees Cook * 791800179c9SKees Cook * Block hardlink when all of: 792800179c9SKees Cook * - sysctl_protected_hardlinks enabled 793800179c9SKees Cook * - fsuid does not match inode 794800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 795800179c9SKees Cook * - not CAP_FOWNER 796800179c9SKees Cook * 797800179c9SKees Cook * Returns 0 if successful, -ve on error. 798800179c9SKees Cook */ 799800179c9SKees Cook static int may_linkat(struct path *link) 800800179c9SKees Cook { 801800179c9SKees Cook const struct cred *cred; 802800179c9SKees Cook struct inode *inode; 803800179c9SKees Cook 804800179c9SKees Cook if (!sysctl_protected_hardlinks) 805800179c9SKees Cook return 0; 806800179c9SKees Cook 807800179c9SKees Cook cred = current_cred(); 808800179c9SKees Cook inode = link->dentry->d_inode; 809800179c9SKees Cook 810800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 811800179c9SKees Cook * otherwise, it must be a safe source. 812800179c9SKees Cook */ 81381abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 814800179c9SKees Cook capable(CAP_FOWNER)) 815800179c9SKees Cook return 0; 816800179c9SKees Cook 817a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 818800179c9SKees Cook return -EPERM; 819800179c9SKees Cook } 820800179c9SKees Cook 821def4af30SAl Viro static __always_inline int 822574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 8231da177e4SLinus Torvalds { 8247b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8256d7b5aaeSAl Viro int error; 8266d7b5aaeSAl Viro char *s; 8271da177e4SLinus Torvalds 828844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 829844a3917SAl Viro 8300e794589SAl Viro if (link->mnt == nd->path.mnt) 8310e794589SAl Viro mntget(link->mnt); 8320e794589SAl Viro 8336d7b5aaeSAl Viro error = -ELOOP; 8346d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8356d7b5aaeSAl Viro goto out_put_nd_path; 8366d7b5aaeSAl Viro 837574197e0SAl Viro cond_resched(); 838574197e0SAl Viro current->total_link_count++; 839574197e0SAl Viro 84068ac1234SAl Viro touch_atime(link); 8411da177e4SLinus Torvalds nd_set_link(nd, NULL); 842cd4e91d3SAl Viro 84336f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8446d7b5aaeSAl Viro if (error) 8456d7b5aaeSAl Viro goto out_put_nd_path; 84636f3b4f6SAl Viro 84786acdca1SAl Viro nd->last_type = LAST_BIND; 848def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 849def4af30SAl Viro error = PTR_ERR(*p); 8506d7b5aaeSAl Viro if (IS_ERR(*p)) 851408ef013SChristoph Hellwig goto out_put_nd_path; 8526d7b5aaeSAl Viro 853cc314eefSLinus Torvalds error = 0; 8546d7b5aaeSAl Viro s = nd_get_link(nd); 8556d7b5aaeSAl Viro if (s) { 856443ed254SAl Viro if (unlikely(IS_ERR(s))) { 857443ed254SAl Viro path_put(&nd->path); 858443ed254SAl Viro put_link(nd, link, *p); 859443ed254SAl Viro return PTR_ERR(s); 860443ed254SAl Viro } 861443ed254SAl Viro if (*s == '/') { 8627bd88377SAl Viro if (!nd->root.mnt) 863443ed254SAl Viro set_root(nd); 864443ed254SAl Viro path_put(&nd->path); 865443ed254SAl Viro nd->path = nd->root; 866443ed254SAl Viro path_get(&nd->root); 867443ed254SAl Viro nd->flags |= LOOKUP_JUMPED; 868443ed254SAl Viro } 869443ed254SAl Viro nd->inode = nd->path.dentry->d_inode; 870443ed254SAl Viro error = link_path_walk(s, nd); 8716d7b5aaeSAl Viro if (unlikely(error)) 8726d7b5aaeSAl Viro put_link(nd, link, *p); 873b5fb63c1SChristoph Hellwig } 8746d7b5aaeSAl Viro 8756d7b5aaeSAl Viro return error; 8766d7b5aaeSAl Viro 8776d7b5aaeSAl Viro out_put_nd_path: 87898f6ef64SArnd Bergmann *p = NULL; 8796d7b5aaeSAl Viro path_put(&nd->path); 8806d7b5aaeSAl Viro path_put(link); 8811da177e4SLinus Torvalds return error; 8821da177e4SLinus Torvalds } 8831da177e4SLinus Torvalds 88431e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 88531e6b01fSNick Piggin { 8860714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8870714a533SAl Viro struct mount *parent; 88831e6b01fSNick Piggin struct dentry *mountpoint; 88931e6b01fSNick Piggin 8900714a533SAl Viro parent = mnt->mnt_parent; 8910714a533SAl Viro if (&parent->mnt == path->mnt) 89231e6b01fSNick Piggin return 0; 893a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 89431e6b01fSNick Piggin path->dentry = mountpoint; 8950714a533SAl Viro path->mnt = &parent->mnt; 89631e6b01fSNick Piggin return 1; 89731e6b01fSNick Piggin } 89831e6b01fSNick Piggin 899f015f126SDavid Howells /* 900f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 901f015f126SDavid Howells * 902f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 903f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 904f015f126SDavid Howells * Up is towards /. 905f015f126SDavid Howells * 906f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 907f015f126SDavid Howells * root. 908f015f126SDavid Howells */ 909bab77ebfSAl Viro int follow_up(struct path *path) 9101da177e4SLinus Torvalds { 9110714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9120714a533SAl Viro struct mount *parent; 9131da177e4SLinus Torvalds struct dentry *mountpoint; 91499b7db7bSNick Piggin 91548a066e7SAl Viro read_seqlock_excl(&mount_lock); 9160714a533SAl Viro parent = mnt->mnt_parent; 9173c0a6163SAl Viro if (parent == mnt) { 91848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9191da177e4SLinus Torvalds return 0; 9201da177e4SLinus Torvalds } 9210714a533SAl Viro mntget(&parent->mnt); 922a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 92348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 924bab77ebfSAl Viro dput(path->dentry); 925bab77ebfSAl Viro path->dentry = mountpoint; 926bab77ebfSAl Viro mntput(path->mnt); 9270714a533SAl Viro path->mnt = &parent->mnt; 9281da177e4SLinus Torvalds return 1; 9291da177e4SLinus Torvalds } 9304d359507SAl Viro EXPORT_SYMBOL(follow_up); 9311da177e4SLinus Torvalds 932b5c84bf6SNick Piggin /* 9339875cf80SDavid Howells * Perform an automount 9349875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9359875cf80SDavid Howells * were called with. 9361da177e4SLinus Torvalds */ 9379875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9389875cf80SDavid Howells bool *need_mntput) 93931e6b01fSNick Piggin { 9409875cf80SDavid Howells struct vfsmount *mnt; 941ea5b778aSDavid Howells int err; 9429875cf80SDavid Howells 9439875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9449875cf80SDavid Howells return -EREMOTE; 9459875cf80SDavid Howells 9460ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9470ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9480ec26fd0SMiklos Szeredi * the name. 9490ec26fd0SMiklos Szeredi * 9500ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9515a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9520ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9530ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9540ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9550ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9565a30d8a2SDavid Howells */ 9575a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 958d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9595a30d8a2SDavid Howells path->dentry->d_inode) 9609875cf80SDavid Howells return -EISDIR; 9610ec26fd0SMiklos Szeredi 9629875cf80SDavid Howells current->total_link_count++; 9639875cf80SDavid Howells if (current->total_link_count >= 40) 9649875cf80SDavid Howells return -ELOOP; 9659875cf80SDavid Howells 9669875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9679875cf80SDavid Howells if (IS_ERR(mnt)) { 9689875cf80SDavid Howells /* 9699875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9709875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9719875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9729875cf80SDavid Howells * 9739875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9749875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9759875cf80SDavid Howells * the path is inaccessible and we should say so. 9769875cf80SDavid Howells */ 97749084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9789875cf80SDavid Howells return -EREMOTE; 9799875cf80SDavid Howells return PTR_ERR(mnt); 98031e6b01fSNick Piggin } 981ea5b778aSDavid Howells 9829875cf80SDavid Howells if (!mnt) /* mount collision */ 9839875cf80SDavid Howells return 0; 9849875cf80SDavid Howells 9858aef1884SAl Viro if (!*need_mntput) { 9868aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9878aef1884SAl Viro mntget(path->mnt); 9888aef1884SAl Viro *need_mntput = true; 9898aef1884SAl Viro } 99019a167afSAl Viro err = finish_automount(mnt, path); 991ea5b778aSDavid Howells 992ea5b778aSDavid Howells switch (err) { 993ea5b778aSDavid Howells case -EBUSY: 994ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 99519a167afSAl Viro return 0; 996ea5b778aSDavid Howells case 0: 9978aef1884SAl Viro path_put(path); 9989875cf80SDavid Howells path->mnt = mnt; 9999875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10009875cf80SDavid Howells return 0; 100119a167afSAl Viro default: 100219a167afSAl Viro return err; 10039875cf80SDavid Howells } 100419a167afSAl Viro 1005ea5b778aSDavid Howells } 10069875cf80SDavid Howells 10079875cf80SDavid Howells /* 10089875cf80SDavid Howells * Handle a dentry that is managed in some way. 1009cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10109875cf80SDavid Howells * - Flagged as mountpoint 10119875cf80SDavid Howells * - Flagged as automount point 10129875cf80SDavid Howells * 10139875cf80SDavid Howells * This may only be called in refwalk mode. 10149875cf80SDavid Howells * 10159875cf80SDavid Howells * Serialization is taken care of in namespace.c 10169875cf80SDavid Howells */ 10179875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10189875cf80SDavid Howells { 10198aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10209875cf80SDavid Howells unsigned managed; 10219875cf80SDavid Howells bool need_mntput = false; 10228aef1884SAl Viro int ret = 0; 10239875cf80SDavid Howells 10249875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10259875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10269875cf80SDavid Howells * the components of that value change under us */ 10279875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10289875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10299875cf80SDavid Howells unlikely(managed != 0)) { 1030cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1031cc53ce53SDavid Howells * being held. */ 1032cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1033cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1034cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10351aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1036cc53ce53SDavid Howells if (ret < 0) 10378aef1884SAl Viro break; 1038cc53ce53SDavid Howells } 1039cc53ce53SDavid Howells 10409875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10419875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10429875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10439875cf80SDavid Howells if (mounted) { 10449875cf80SDavid Howells dput(path->dentry); 10459875cf80SDavid Howells if (need_mntput) 1046463ffb2eSAl Viro mntput(path->mnt); 1047463ffb2eSAl Viro path->mnt = mounted; 1048463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10499875cf80SDavid Howells need_mntput = true; 10509875cf80SDavid Howells continue; 1051463ffb2eSAl Viro } 1052463ffb2eSAl Viro 10539875cf80SDavid Howells /* Something is mounted on this dentry in another 10549875cf80SDavid Howells * namespace and/or whatever was mounted there in this 105548a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 105648a066e7SAl Viro * get it */ 10571da177e4SLinus Torvalds } 10589875cf80SDavid Howells 10599875cf80SDavid Howells /* Handle an automount point */ 10609875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10619875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10629875cf80SDavid Howells if (ret < 0) 10638aef1884SAl Viro break; 10649875cf80SDavid Howells continue; 10659875cf80SDavid Howells } 10669875cf80SDavid Howells 10679875cf80SDavid Howells /* We didn't change the current path point */ 10689875cf80SDavid Howells break; 10699875cf80SDavid Howells } 10708aef1884SAl Viro 10718aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10728aef1884SAl Viro mntput(path->mnt); 10738aef1884SAl Viro if (ret == -EISDIR) 10748aef1884SAl Viro ret = 0; 1075a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10761da177e4SLinus Torvalds } 10771da177e4SLinus Torvalds 1078cc53ce53SDavid Howells int follow_down_one(struct path *path) 10791da177e4SLinus Torvalds { 10801da177e4SLinus Torvalds struct vfsmount *mounted; 10811da177e4SLinus Torvalds 10821c755af4SAl Viro mounted = lookup_mnt(path); 10831da177e4SLinus Torvalds if (mounted) { 10849393bd07SAl Viro dput(path->dentry); 10859393bd07SAl Viro mntput(path->mnt); 10869393bd07SAl Viro path->mnt = mounted; 10879393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10881da177e4SLinus Torvalds return 1; 10891da177e4SLinus Torvalds } 10901da177e4SLinus Torvalds return 0; 10911da177e4SLinus Torvalds } 10924d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 10931da177e4SLinus Torvalds 1094b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 109562a7375eSIan Kent { 1096b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1097b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 109862a7375eSIan Kent } 109962a7375eSIan Kent 11009875cf80SDavid Howells /* 1101287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1102287548e4SAl Viro * we meet a managed dentry that would need blocking. 11039875cf80SDavid Howells */ 11049875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1105287548e4SAl Viro struct inode **inode) 11069875cf80SDavid Howells { 110762a7375eSIan Kent for (;;) { 1108c7105365SAl Viro struct mount *mounted; 110962a7375eSIan Kent /* 111062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 111162a7375eSIan Kent * that wants to block transit. 111262a7375eSIan Kent */ 1113b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1114b8faf035SNeilBrown case -ECHILD: 1115b8faf035SNeilBrown default: 1116ab90911fSDavid Howells return false; 1117b8faf035SNeilBrown case -EISDIR: 1118b8faf035SNeilBrown return true; 1119b8faf035SNeilBrown case 0: 1120b8faf035SNeilBrown break; 1121b8faf035SNeilBrown } 112262a7375eSIan Kent 112362a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1124b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 112562a7375eSIan Kent 1126474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11279875cf80SDavid Howells if (!mounted) 11289875cf80SDavid Howells break; 1129c7105365SAl Viro path->mnt = &mounted->mnt; 1130c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1131a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11329875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 113359430262SLinus Torvalds /* 113459430262SLinus Torvalds * Update the inode too. We don't need to re-check the 113559430262SLinus Torvalds * dentry sequence number here after this d_inode read, 113659430262SLinus Torvalds * because a mount-point is always pinned. 113759430262SLinus Torvalds */ 113859430262SLinus Torvalds *inode = path->dentry->d_inode; 11399875cf80SDavid Howells } 1140f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1141b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1142287548e4SAl Viro } 1143287548e4SAl Viro 114431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 114531e6b01fSNick Piggin { 11464023bfc9SAl Viro struct inode *inode = nd->inode; 11477bd88377SAl Viro if (!nd->root.mnt) 114831e6b01fSNick Piggin set_root_rcu(nd); 114931e6b01fSNick Piggin 115031e6b01fSNick Piggin while (1) { 115131e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 115231e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 115331e6b01fSNick Piggin break; 115431e6b01fSNick Piggin } 115531e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 115631e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 115731e6b01fSNick Piggin struct dentry *parent = old->d_parent; 115831e6b01fSNick Piggin unsigned seq; 115931e6b01fSNick Piggin 11604023bfc9SAl Viro inode = parent->d_inode; 116131e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 116231e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1163ef7562d5SAl Viro goto failed; 116431e6b01fSNick Piggin nd->path.dentry = parent; 116531e6b01fSNick Piggin nd->seq = seq; 116631e6b01fSNick Piggin break; 116731e6b01fSNick Piggin } 116831e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 116931e6b01fSNick Piggin break; 11704023bfc9SAl Viro inode = nd->path.dentry->d_inode; 117131e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 117231e6b01fSNick Piggin } 1173b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1174b37199e6SAl Viro struct mount *mounted; 1175b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1176b37199e6SAl Viro if (!mounted) 1177b37199e6SAl Viro break; 1178b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1179b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 11804023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1181b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1182f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1183b37199e6SAl Viro goto failed; 1184b37199e6SAl Viro } 11854023bfc9SAl Viro nd->inode = inode; 118631e6b01fSNick Piggin return 0; 1187ef7562d5SAl Viro 1188ef7562d5SAl Viro failed: 1189ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11905b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1191ef7562d5SAl Viro nd->root.mnt = NULL; 11928b61e74fSAl Viro rcu_read_unlock(); 1193ef7562d5SAl Viro return -ECHILD; 119431e6b01fSNick Piggin } 119531e6b01fSNick Piggin 11969875cf80SDavid Howells /* 1197cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1198cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1199cc53ce53SDavid Howells * caller is permitted to proceed or not. 1200cc53ce53SDavid Howells */ 12017cc90cc3SAl Viro int follow_down(struct path *path) 1202cc53ce53SDavid Howells { 1203cc53ce53SDavid Howells unsigned managed; 1204cc53ce53SDavid Howells int ret; 1205cc53ce53SDavid Howells 1206cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1207cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1208cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1209cc53ce53SDavid Howells * being held. 1210cc53ce53SDavid Howells * 1211cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1212cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1213cc53ce53SDavid Howells * other than its daemon the right to mount on its 1214cc53ce53SDavid Howells * superstructure. 1215cc53ce53SDavid Howells * 1216cc53ce53SDavid Howells * The filesystem may sleep at this point. 1217cc53ce53SDavid Howells */ 1218cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1219cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1220cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1221ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12221aed3e42SAl Viro path->dentry, false); 1223cc53ce53SDavid Howells if (ret < 0) 1224cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1225cc53ce53SDavid Howells } 1226cc53ce53SDavid Howells 1227cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1228cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1229cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1230cc53ce53SDavid Howells if (!mounted) 1231cc53ce53SDavid Howells break; 1232cc53ce53SDavid Howells dput(path->dentry); 1233cc53ce53SDavid Howells mntput(path->mnt); 1234cc53ce53SDavid Howells path->mnt = mounted; 1235cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1236cc53ce53SDavid Howells continue; 1237cc53ce53SDavid Howells } 1238cc53ce53SDavid Howells 1239cc53ce53SDavid Howells /* Don't handle automount points here */ 1240cc53ce53SDavid Howells break; 1241cc53ce53SDavid Howells } 1242cc53ce53SDavid Howells return 0; 1243cc53ce53SDavid Howells } 12444d359507SAl Viro EXPORT_SYMBOL(follow_down); 1245cc53ce53SDavid Howells 1246cc53ce53SDavid Howells /* 12479875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12489875cf80SDavid Howells */ 12499875cf80SDavid Howells static void follow_mount(struct path *path) 12509875cf80SDavid Howells { 12519875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12529875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12539875cf80SDavid Howells if (!mounted) 12549875cf80SDavid Howells break; 12559875cf80SDavid Howells dput(path->dentry); 12569875cf80SDavid Howells mntput(path->mnt); 12579875cf80SDavid Howells path->mnt = mounted; 12589875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12599875cf80SDavid Howells } 12609875cf80SDavid Howells } 12619875cf80SDavid Howells 126231e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12631da177e4SLinus Torvalds { 12647bd88377SAl Viro if (!nd->root.mnt) 12652a737871SAl Viro set_root(nd); 1266e518ddb7SAndreas Mohr 12671da177e4SLinus Torvalds while(1) { 12684ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12691da177e4SLinus Torvalds 12702a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12712a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12721da177e4SLinus Torvalds break; 12731da177e4SLinus Torvalds } 12744ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12753088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12763088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12771da177e4SLinus Torvalds dput(old); 12781da177e4SLinus Torvalds break; 12791da177e4SLinus Torvalds } 12803088dd70SAl Viro if (!follow_up(&nd->path)) 12811da177e4SLinus Torvalds break; 12821da177e4SLinus Torvalds } 128379ed0226SAl Viro follow_mount(&nd->path); 128431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12851da177e4SLinus Torvalds } 12861da177e4SLinus Torvalds 12871da177e4SLinus Torvalds /* 1288bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1289bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1290bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1291bad61189SMiklos Szeredi * 1292bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1293baa03890SNick Piggin */ 1294bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1295201f956eSAl Viro unsigned int flags, bool *need_lookup) 1296baa03890SNick Piggin { 1297baa03890SNick Piggin struct dentry *dentry; 1298bad61189SMiklos Szeredi int error; 1299baa03890SNick Piggin 1300bad61189SMiklos Szeredi *need_lookup = false; 1301bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1302bad61189SMiklos Szeredi if (dentry) { 130339e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1304201f956eSAl Viro error = d_revalidate(dentry, flags); 1305bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1306bad61189SMiklos Szeredi if (error < 0) { 1307bad61189SMiklos Szeredi dput(dentry); 1308bad61189SMiklos Szeredi return ERR_PTR(error); 1309bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1310bad61189SMiklos Szeredi dput(dentry); 1311bad61189SMiklos Szeredi dentry = NULL; 1312bad61189SMiklos Szeredi } 1313bad61189SMiklos Szeredi } 1314bad61189SMiklos Szeredi } 1315bad61189SMiklos Szeredi } 1316baa03890SNick Piggin 1317bad61189SMiklos Szeredi if (!dentry) { 1318bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1319baa03890SNick Piggin if (unlikely(!dentry)) 1320baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1321baa03890SNick Piggin 1322bad61189SMiklos Szeredi *need_lookup = true; 1323baa03890SNick Piggin } 1324baa03890SNick Piggin return dentry; 1325baa03890SNick Piggin } 1326baa03890SNick Piggin 1327baa03890SNick Piggin /* 132813a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 132913a2c3beSJ. Bruce Fields * unhashed. 1330bad61189SMiklos Szeredi * 1331bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 133244396f4bSJosef Bacik */ 1333bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 133472bd866aSAl Viro unsigned int flags) 133544396f4bSJosef Bacik { 133644396f4bSJosef Bacik struct dentry *old; 133744396f4bSJosef Bacik 133844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1339bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1340e188dc02SMiklos Szeredi dput(dentry); 134144396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1342e188dc02SMiklos Szeredi } 134344396f4bSJosef Bacik 134472bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 134544396f4bSJosef Bacik if (unlikely(old)) { 134644396f4bSJosef Bacik dput(dentry); 134744396f4bSJosef Bacik dentry = old; 134844396f4bSJosef Bacik } 134944396f4bSJosef Bacik return dentry; 135044396f4bSJosef Bacik } 135144396f4bSJosef Bacik 1352a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 135372bd866aSAl Viro struct dentry *base, unsigned int flags) 1354a3255546SAl Viro { 1355bad61189SMiklos Szeredi bool need_lookup; 1356a3255546SAl Viro struct dentry *dentry; 1357a3255546SAl Viro 135872bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1359bad61189SMiklos Szeredi if (!need_lookup) 1360a3255546SAl Viro return dentry; 1361bad61189SMiklos Szeredi 136272bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1363a3255546SAl Viro } 1364a3255546SAl Viro 136544396f4bSJosef Bacik /* 13661da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13671da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13681da177e4SLinus Torvalds * It _is_ time-critical. 13691da177e4SLinus Torvalds */ 1370e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 137131e6b01fSNick Piggin struct path *path, struct inode **inode) 13721da177e4SLinus Torvalds { 13734ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 137431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13755a18fff2SAl Viro int need_reval = 1; 13765a18fff2SAl Viro int status = 1; 13779875cf80SDavid Howells int err; 13789875cf80SDavid Howells 13793cac260aSAl Viro /* 1380b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1381b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1382b04f784eSNick Piggin * do the non-racy lookup, below. 1383b04f784eSNick Piggin */ 138431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 138531e6b01fSNick Piggin unsigned seq; 1386da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13875a18fff2SAl Viro if (!dentry) 13885a18fff2SAl Viro goto unlazy; 13895a18fff2SAl Viro 139012f8ad4bSLinus Torvalds /* 139112f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 139212f8ad4bSLinus Torvalds * the dentry name information from lookup. 139312f8ad4bSLinus Torvalds */ 139412f8ad4bSLinus Torvalds *inode = dentry->d_inode; 139512f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 139612f8ad4bSLinus Torvalds return -ECHILD; 139712f8ad4bSLinus Torvalds 139812f8ad4bSLinus Torvalds /* 139912f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 140012f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 140112f8ad4bSLinus Torvalds * 140212f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 140312f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 140412f8ad4bSLinus Torvalds */ 140531e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 140631e6b01fSNick Piggin return -ECHILD; 140731e6b01fSNick Piggin nd->seq = seq; 14085a18fff2SAl Viro 140924643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14104ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14115a18fff2SAl Viro if (unlikely(status <= 0)) { 14125a18fff2SAl Viro if (status != -ECHILD) 14135a18fff2SAl Viro need_reval = 0; 14145a18fff2SAl Viro goto unlazy; 14155a18fff2SAl Viro } 141624643087SAl Viro } 141731e6b01fSNick Piggin path->mnt = mnt; 141831e6b01fSNick Piggin path->dentry = dentry; 1419b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14209875cf80SDavid Howells return 0; 14215a18fff2SAl Viro unlazy: 142219660af7SAl Viro if (unlazy_walk(nd, dentry)) 14235a18fff2SAl Viro return -ECHILD; 14245a18fff2SAl Viro } else { 1425e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 142624643087SAl Viro } 14275a18fff2SAl Viro 142881e6f520SAl Viro if (unlikely(!dentry)) 142981e6f520SAl Viro goto need_lookup; 14305a18fff2SAl Viro 14315a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14324ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14335a18fff2SAl Viro if (unlikely(status <= 0)) { 14345a18fff2SAl Viro if (status < 0) { 14355a18fff2SAl Viro dput(dentry); 14365a18fff2SAl Viro return status; 14375a18fff2SAl Viro } 14385a18fff2SAl Viro if (!d_invalidate(dentry)) { 14395a18fff2SAl Viro dput(dentry); 144081e6f520SAl Viro goto need_lookup; 14415a18fff2SAl Viro } 14425a18fff2SAl Viro } 1443697f514dSMiklos Szeredi 14441da177e4SLinus Torvalds path->mnt = mnt; 14451da177e4SLinus Torvalds path->dentry = dentry; 14469875cf80SDavid Howells err = follow_managed(path, nd->flags); 144789312214SIan Kent if (unlikely(err < 0)) { 144889312214SIan Kent path_put_conditional(path, nd); 14499875cf80SDavid Howells return err; 145089312214SIan Kent } 1451a3fbbde7SAl Viro if (err) 1452a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 145331e6b01fSNick Piggin *inode = path->dentry->d_inode; 14541da177e4SLinus Torvalds return 0; 145581e6f520SAl Viro 145681e6f520SAl Viro need_lookup: 1457697f514dSMiklos Szeredi return 1; 1458697f514dSMiklos Szeredi } 1459697f514dSMiklos Szeredi 1460697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1461cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1462697f514dSMiklos Szeredi { 1463697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1464697f514dSMiklos Szeredi int err; 1465697f514dSMiklos Szeredi 1466697f514dSMiklos Szeredi parent = nd->path.dentry; 146781e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 146881e6f520SAl Viro 146981e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1470cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 147181e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 147281e6f520SAl Viro if (IS_ERR(dentry)) 147381e6f520SAl Viro return PTR_ERR(dentry); 1474697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1475697f514dSMiklos Szeredi path->dentry = dentry; 1476697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1477697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1478697f514dSMiklos Szeredi path_put_conditional(path, nd); 1479697f514dSMiklos Szeredi return err; 1480697f514dSMiklos Szeredi } 1481697f514dSMiklos Szeredi if (err) 1482697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1483697f514dSMiklos Szeredi return 0; 14841da177e4SLinus Torvalds } 14851da177e4SLinus Torvalds 148652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 148752094c8aSAl Viro { 148852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14894ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 149052094c8aSAl Viro if (err != -ECHILD) 149152094c8aSAl Viro return err; 149219660af7SAl Viro if (unlazy_walk(nd, NULL)) 149352094c8aSAl Viro return -ECHILD; 149452094c8aSAl Viro } 14954ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 149652094c8aSAl Viro } 149752094c8aSAl Viro 14989856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 14999856fa1bSAl Viro { 15009856fa1bSAl Viro if (type == LAST_DOTDOT) { 15019856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15029856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15039856fa1bSAl Viro return -ECHILD; 15049856fa1bSAl Viro } else 15059856fa1bSAl Viro follow_dotdot(nd); 15069856fa1bSAl Viro } 15079856fa1bSAl Viro return 0; 15089856fa1bSAl Viro } 15099856fa1bSAl Viro 1510951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1511951361f9SAl Viro { 1512951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1513951361f9SAl Viro path_put(&nd->path); 1514951361f9SAl Viro } else { 1515951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15165b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1517951361f9SAl Viro nd->root.mnt = NULL; 15188b61e74fSAl Viro rcu_read_unlock(); 1519951361f9SAl Viro } 1520951361f9SAl Viro } 1521951361f9SAl Viro 15223ddcd056SLinus Torvalds /* 15233ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15243ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15253ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15263ddcd056SLinus Torvalds * for the common case. 15273ddcd056SLinus Torvalds */ 1528b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15293ddcd056SLinus Torvalds { 1530b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15313ddcd056SLinus Torvalds } 15323ddcd056SLinus Torvalds 1533ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 153421b9b073SAl Viro int follow) 1535ce57dfc1SAl Viro { 1536ce57dfc1SAl Viro struct inode *inode; 1537ce57dfc1SAl Viro int err; 1538ce57dfc1SAl Viro /* 1539ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1540ce57dfc1SAl Viro * to be able to know about the current root directory and 1541ce57dfc1SAl Viro * parent relationships. 1542ce57dfc1SAl Viro */ 154321b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 154421b9b073SAl Viro return handle_dots(nd, nd->last_type); 1545e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1546ce57dfc1SAl Viro if (unlikely(err)) { 1547697f514dSMiklos Szeredi if (err < 0) 1548697f514dSMiklos Szeredi goto out_err; 1549697f514dSMiklos Szeredi 1550cc2a5271SAl Viro err = lookup_slow(nd, path); 1551697f514dSMiklos Szeredi if (err < 0) 1552697f514dSMiklos Szeredi goto out_err; 1553697f514dSMiklos Szeredi 1554697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1555ce57dfc1SAl Viro } 1556697f514dSMiklos Szeredi err = -ENOENT; 155722213318SAl Viro if (!inode || d_is_negative(path->dentry)) 1558697f514dSMiklos Szeredi goto out_path_put; 1559697f514dSMiklos Szeredi 1560b18825a7SDavid Howells if (should_follow_link(path->dentry, follow)) { 156119660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 156219660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1563697f514dSMiklos Szeredi err = -ECHILD; 1564697f514dSMiklos Szeredi goto out_err; 156519660af7SAl Viro } 156619660af7SAl Viro } 1567ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1568ce57dfc1SAl Viro return 1; 1569ce57dfc1SAl Viro } 1570ce57dfc1SAl Viro path_to_nameidata(path, nd); 1571ce57dfc1SAl Viro nd->inode = inode; 1572ce57dfc1SAl Viro return 0; 1573697f514dSMiklos Szeredi 1574697f514dSMiklos Szeredi out_path_put: 1575697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1576697f514dSMiklos Szeredi out_err: 1577697f514dSMiklos Szeredi terminate_walk(nd); 1578697f514dSMiklos Szeredi return err; 1579ce57dfc1SAl Viro } 1580ce57dfc1SAl Viro 15811da177e4SLinus Torvalds /* 1582b356379aSAl Viro * This limits recursive symlink follows to 8, while 1583b356379aSAl Viro * limiting consecutive symlinks to 40. 1584b356379aSAl Viro * 1585b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1586b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1587b356379aSAl Viro */ 1588b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1589b356379aSAl Viro { 1590b356379aSAl Viro int res; 1591b356379aSAl Viro 1592b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1593b356379aSAl Viro path_put_conditional(path, nd); 1594b356379aSAl Viro path_put(&nd->path); 1595b356379aSAl Viro return -ELOOP; 1596b356379aSAl Viro } 15971a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1598b356379aSAl Viro 1599b356379aSAl Viro nd->depth++; 1600b356379aSAl Viro current->link_count++; 1601b356379aSAl Viro 1602b356379aSAl Viro do { 1603b356379aSAl Viro struct path link = *path; 1604b356379aSAl Viro void *cookie; 1605574197e0SAl Viro 1606574197e0SAl Viro res = follow_link(&link, nd, &cookie); 16076d7b5aaeSAl Viro if (res) 16086d7b5aaeSAl Viro break; 160921b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1610574197e0SAl Viro put_link(nd, &link, cookie); 1611b356379aSAl Viro } while (res > 0); 1612b356379aSAl Viro 1613b356379aSAl Viro current->link_count--; 1614b356379aSAl Viro nd->depth--; 1615b356379aSAl Viro return res; 1616b356379aSAl Viro } 1617b356379aSAl Viro 1618b356379aSAl Viro /* 1619bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1620bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1621bfcfaa77SLinus Torvalds * 1622bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1623bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1624bfcfaa77SLinus Torvalds * fast. 1625bfcfaa77SLinus Torvalds * 1626bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1627bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1628bfcfaa77SLinus Torvalds * crossing operation. 1629bfcfaa77SLinus Torvalds * 1630bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1631bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1632bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1633bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1634bfcfaa77SLinus Torvalds */ 1635bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1636bfcfaa77SLinus Torvalds 1637f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1638bfcfaa77SLinus Torvalds 1639f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1640bfcfaa77SLinus Torvalds 1641bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1642bfcfaa77SLinus Torvalds { 164399d263d4SLinus Torvalds return hash_64(hash, 32); 1644bfcfaa77SLinus Torvalds } 1645bfcfaa77SLinus Torvalds 1646bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1647bfcfaa77SLinus Torvalds 1648bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1649bfcfaa77SLinus Torvalds 1650bfcfaa77SLinus Torvalds #endif 1651bfcfaa77SLinus Torvalds 1652bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1653bfcfaa77SLinus Torvalds { 1654bfcfaa77SLinus Torvalds unsigned long a, mask; 1655bfcfaa77SLinus Torvalds unsigned long hash = 0; 1656bfcfaa77SLinus Torvalds 1657bfcfaa77SLinus Torvalds for (;;) { 1658e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1659bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1660bfcfaa77SLinus Torvalds break; 1661bfcfaa77SLinus Torvalds hash += a; 1662f132c5beSAl Viro hash *= 9; 1663bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1664bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1665bfcfaa77SLinus Torvalds if (!len) 1666bfcfaa77SLinus Torvalds goto done; 1667bfcfaa77SLinus Torvalds } 1668a5c21dceSWill Deacon mask = bytemask_from_count(len); 1669bfcfaa77SLinus Torvalds hash += mask & a; 1670bfcfaa77SLinus Torvalds done: 1671bfcfaa77SLinus Torvalds return fold_hash(hash); 1672bfcfaa77SLinus Torvalds } 1673bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1674bfcfaa77SLinus Torvalds 1675bfcfaa77SLinus Torvalds /* 1676bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1677d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1678bfcfaa77SLinus Torvalds */ 1679d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1680bfcfaa77SLinus Torvalds { 168136126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 168236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1683bfcfaa77SLinus Torvalds 1684bfcfaa77SLinus Torvalds hash = a = 0; 1685bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1686bfcfaa77SLinus Torvalds do { 1687bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1688bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1689e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 169036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 169136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1692bfcfaa77SLinus Torvalds 169336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 169436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 169536126f8fSLinus Torvalds 169636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 169736126f8fSLinus Torvalds 169836126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 16999226b5b4SLinus Torvalds len += find_zero(mask); 1700d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1701bfcfaa77SLinus Torvalds } 1702bfcfaa77SLinus Torvalds 1703bfcfaa77SLinus Torvalds #else 1704bfcfaa77SLinus Torvalds 17050145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17060145acc2SLinus Torvalds { 17070145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17080145acc2SLinus Torvalds while (len--) 17090145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17100145acc2SLinus Torvalds return end_name_hash(hash); 17110145acc2SLinus Torvalds } 1712ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17130145acc2SLinus Torvalds 17143ddcd056SLinus Torvalds /* 1715200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1716200e9ef7SLinus Torvalds * one character. 1717200e9ef7SLinus Torvalds */ 1718d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1719200e9ef7SLinus Torvalds { 1720200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1721200e9ef7SLinus Torvalds unsigned long len = 0, c; 1722200e9ef7SLinus Torvalds 1723200e9ef7SLinus Torvalds c = (unsigned char)*name; 1724200e9ef7SLinus Torvalds do { 1725200e9ef7SLinus Torvalds len++; 1726200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1727200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1728200e9ef7SLinus Torvalds } while (c && c != '/'); 1729d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1730200e9ef7SLinus Torvalds } 1731200e9ef7SLinus Torvalds 1732bfcfaa77SLinus Torvalds #endif 1733bfcfaa77SLinus Torvalds 1734200e9ef7SLinus Torvalds /* 17351da177e4SLinus Torvalds * Name resolution. 1736ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1737ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17381da177e4SLinus Torvalds * 1739ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1740ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17411da177e4SLinus Torvalds */ 17426de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17431da177e4SLinus Torvalds { 17441da177e4SLinus Torvalds struct path next; 17451da177e4SLinus Torvalds int err; 17461da177e4SLinus Torvalds 17471da177e4SLinus Torvalds while (*name=='/') 17481da177e4SLinus Torvalds name++; 17491da177e4SLinus Torvalds if (!*name) 1750086e183aSAl Viro return 0; 17511da177e4SLinus Torvalds 17521da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17531da177e4SLinus Torvalds for(;;) { 1754d6bb3e90SLinus Torvalds u64 hash_len; 1755fe479a58SAl Viro int type; 17561da177e4SLinus Torvalds 175752094c8aSAl Viro err = may_lookup(nd); 17581da177e4SLinus Torvalds if (err) 17591da177e4SLinus Torvalds break; 17601da177e4SLinus Torvalds 1761d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17621da177e4SLinus Torvalds 1763fe479a58SAl Viro type = LAST_NORM; 1764d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1765fe479a58SAl Viro case 2: 1766200e9ef7SLinus Torvalds if (name[1] == '.') { 1767fe479a58SAl Viro type = LAST_DOTDOT; 176816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 176916c2cd71SAl Viro } 1770fe479a58SAl Viro break; 1771fe479a58SAl Viro case 1: 1772fe479a58SAl Viro type = LAST_DOT; 1773fe479a58SAl Viro } 17745a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17755a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 177616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17775a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1778a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1779da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 17805a202bcdSAl Viro if (err < 0) 17815a202bcdSAl Viro break; 1782d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1783d6bb3e90SLinus Torvalds name = this.name; 17845a202bcdSAl Viro } 17855a202bcdSAl Viro } 1786fe479a58SAl Viro 1787d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1788d6bb3e90SLinus Torvalds nd->last.name = name; 17895f4a6a69SAl Viro nd->last_type = type; 17905f4a6a69SAl Viro 1791d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1792d6bb3e90SLinus Torvalds if (!*name) 17935f4a6a69SAl Viro return 0; 1794200e9ef7SLinus Torvalds /* 1795200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1796200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1797200e9ef7SLinus Torvalds */ 1798200e9ef7SLinus Torvalds do { 1799d6bb3e90SLinus Torvalds name++; 1800d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1801d6bb3e90SLinus Torvalds if (!*name) 18025f4a6a69SAl Viro return 0; 18035f4a6a69SAl Viro 180421b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1805ce57dfc1SAl Viro if (err < 0) 1806ce57dfc1SAl Viro return err; 1807fe479a58SAl Viro 1808ce57dfc1SAl Viro if (err) { 1809b356379aSAl Viro err = nested_symlink(&next, nd); 18101da177e4SLinus Torvalds if (err) 1811a7472babSAl Viro return err; 181231e6b01fSNick Piggin } 181344b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18143ddcd056SLinus Torvalds err = -ENOTDIR; 18153ddcd056SLinus Torvalds break; 18165f4a6a69SAl Viro } 1817ce57dfc1SAl Viro } 1818951361f9SAl Viro terminate_walk(nd); 18191da177e4SLinus Torvalds return err; 18201da177e4SLinus Torvalds } 18211da177e4SLinus Torvalds 182270e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 182370e9b357SAl Viro struct nameidata *nd, struct file **fp) 182431e6b01fSNick Piggin { 182531e6b01fSNick Piggin int retval = 0; 182631e6b01fSNick Piggin 182731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 182816c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 182931e6b01fSNick Piggin nd->depth = 0; 18305b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1831b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1832b18825a7SDavid Howells struct inode *inode = root->d_inode; 183373d049a4SAl Viro if (*name) { 183444b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18355b6ca027SAl Viro return -ENOTDIR; 18365b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18375b6ca027SAl Viro if (retval) 18385b6ca027SAl Viro return retval; 183973d049a4SAl Viro } 18405b6ca027SAl Viro nd->path = nd->root; 18415b6ca027SAl Viro nd->inode = inode; 18425b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18438b61e74fSAl Viro rcu_read_lock(); 18445b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 184548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18465b6ca027SAl Viro } else { 18475b6ca027SAl Viro path_get(&nd->path); 18485b6ca027SAl Viro } 18495b6ca027SAl Viro return 0; 18505b6ca027SAl Viro } 18515b6ca027SAl Viro 185231e6b01fSNick Piggin nd->root.mnt = NULL; 185331e6b01fSNick Piggin 185448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 185531e6b01fSNick Piggin if (*name=='/') { 1856e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18578b61e74fSAl Viro rcu_read_lock(); 18587bd88377SAl Viro nd->seq = set_root_rcu(nd); 1859e41f7d4eSAl Viro } else { 1860e41f7d4eSAl Viro set_root(nd); 1861e41f7d4eSAl Viro path_get(&nd->root); 1862e41f7d4eSAl Viro } 186331e6b01fSNick Piggin nd->path = nd->root; 186431e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1865e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 186631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1867c28cc364SNick Piggin unsigned seq; 186831e6b01fSNick Piggin 18698b61e74fSAl Viro rcu_read_lock(); 187031e6b01fSNick Piggin 1871c28cc364SNick Piggin do { 1872c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 187331e6b01fSNick Piggin nd->path = fs->pwd; 1874c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1875c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1876e41f7d4eSAl Viro } else { 1877e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1878e41f7d4eSAl Viro } 187931e6b01fSNick Piggin } else { 1880582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 18812903ff01SAl Viro struct fd f = fdget_raw(dfd); 188231e6b01fSNick Piggin struct dentry *dentry; 188331e6b01fSNick Piggin 18842903ff01SAl Viro if (!f.file) 18852903ff01SAl Viro return -EBADF; 188631e6b01fSNick Piggin 18872903ff01SAl Viro dentry = f.file->f_path.dentry; 188831e6b01fSNick Piggin 1889f52e0c11SAl Viro if (*name) { 189044b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 18912903ff01SAl Viro fdput(f); 18922903ff01SAl Viro return -ENOTDIR; 1893f52e0c11SAl Viro } 18942903ff01SAl Viro } 18952903ff01SAl Viro 18962903ff01SAl Viro nd->path = f.file->f_path; 1897e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18989c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 18992903ff01SAl Viro *fp = f.file; 1900c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19018b61e74fSAl Viro rcu_read_lock(); 19025590ff0dSUlrich Drepper } else { 19032903ff01SAl Viro path_get(&nd->path); 19042903ff01SAl Viro fdput(f); 19051da177e4SLinus Torvalds } 1906e41f7d4eSAl Viro } 1907e41f7d4eSAl Viro 190831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19094023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 19109b4a9b14SAl Viro return 0; 19114023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 19124023bfc9SAl Viro return 0; 19134023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19144023bfc9SAl Viro nd->root.mnt = NULL; 19154023bfc9SAl Viro rcu_read_unlock(); 19164023bfc9SAl Viro return -ECHILD; 19179b4a9b14SAl Viro } 19189b4a9b14SAl Viro 1919bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1920bd92d7feSAl Viro { 1921bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1922bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1923bd92d7feSAl Viro 1924bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 192521b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1926bd92d7feSAl Viro } 1927bd92d7feSAl Viro 19289b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1929ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19309b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19319b4a9b14SAl Viro { 193270e9b357SAl Viro struct file *base = NULL; 1933bd92d7feSAl Viro struct path path; 1934bd92d7feSAl Viro int err; 193531e6b01fSNick Piggin 193631e6b01fSNick Piggin /* 193731e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 193831e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 193931e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 194031e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 194131e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 194231e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 194331e6b01fSNick Piggin * analogue, foo_rcu(). 194431e6b01fSNick Piggin * 194531e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 194631e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 194731e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 194831e6b01fSNick Piggin * be able to complete). 194931e6b01fSNick Piggin */ 1950bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1951ee0827cdSAl Viro 1952bd92d7feSAl Viro if (unlikely(err)) 1953bd92d7feSAl Viro return err; 1954ee0827cdSAl Viro 1955ee0827cdSAl Viro current->total_link_count = 0; 1956bd92d7feSAl Viro err = link_path_walk(name, nd); 1957bd92d7feSAl Viro 1958bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1959bd92d7feSAl Viro err = lookup_last(nd, &path); 1960bd92d7feSAl Viro while (err > 0) { 1961bd92d7feSAl Viro void *cookie; 1962bd92d7feSAl Viro struct path link = path; 1963800179c9SKees Cook err = may_follow_link(&link, nd); 1964800179c9SKees Cook if (unlikely(err)) 1965800179c9SKees Cook break; 1966bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1967574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19686d7b5aaeSAl Viro if (err) 19696d7b5aaeSAl Viro break; 1970bd92d7feSAl Viro err = lookup_last(nd, &path); 1971574197e0SAl Viro put_link(nd, &link, cookie); 1972bd92d7feSAl Viro } 1973bd92d7feSAl Viro } 1974ee0827cdSAl Viro 19759f1fafeeSAl Viro if (!err) 19769f1fafeeSAl Viro err = complete_walk(nd); 1977bd92d7feSAl Viro 1978bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 197944b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 1980bd92d7feSAl Viro path_put(&nd->path); 1981bd23a539SAl Viro err = -ENOTDIR; 1982bd92d7feSAl Viro } 1983bd92d7feSAl Viro } 198416c2cd71SAl Viro 198570e9b357SAl Viro if (base) 198670e9b357SAl Viro fput(base); 1987ee0827cdSAl Viro 19885b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 198931e6b01fSNick Piggin path_put(&nd->root); 199031e6b01fSNick Piggin nd->root.mnt = NULL; 199131e6b01fSNick Piggin } 1992bd92d7feSAl Viro return err; 199331e6b01fSNick Piggin } 199431e6b01fSNick Piggin 1995873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 1996873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 1997873f1eedSJeff Layton { 1998873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 1999873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2000873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 2001873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2002873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 2003873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 2004873f1eedSJeff Layton 2005873f1eedSJeff Layton if (likely(!retval)) 2006adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2007873f1eedSJeff Layton return retval; 2008873f1eedSJeff Layton } 2009873f1eedSJeff Layton 2010ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 2011ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 2012ee0827cdSAl Viro { 2013873f1eedSJeff Layton struct filename filename = { .name = name }; 2014ee0827cdSAl Viro 2015873f1eedSJeff Layton return filename_lookup(dfd, &filename, flags, nd); 20161da177e4SLinus Torvalds } 20171da177e4SLinus Torvalds 201879714f72SAl Viro /* does lookup, returns the object with parent locked */ 201979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20205590ff0dSUlrich Drepper { 202179714f72SAl Viro struct nameidata nd; 202279714f72SAl Viro struct dentry *d; 202379714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 202479714f72SAl Viro if (err) 202579714f72SAl Viro return ERR_PTR(err); 202679714f72SAl Viro if (nd.last_type != LAST_NORM) { 202779714f72SAl Viro path_put(&nd.path); 202879714f72SAl Viro return ERR_PTR(-EINVAL); 202979714f72SAl Viro } 203079714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20311e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 203279714f72SAl Viro if (IS_ERR(d)) { 203379714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 203479714f72SAl Viro path_put(&nd.path); 203579714f72SAl Viro return d; 203679714f72SAl Viro } 203779714f72SAl Viro *path = nd.path; 203879714f72SAl Viro return d; 20395590ff0dSUlrich Drepper } 20405590ff0dSUlrich Drepper 2041d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2042d1811465SAl Viro { 2043d1811465SAl Viro struct nameidata nd; 2044d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2045d1811465SAl Viro if (!res) 2046d1811465SAl Viro *path = nd.path; 2047d1811465SAl Viro return res; 2048d1811465SAl Viro } 20494d359507SAl Viro EXPORT_SYMBOL(kern_path); 2050d1811465SAl Viro 205116f18200SJosef 'Jeff' Sipek /** 205216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 205316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 205416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 205516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 205616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2057e0a01249SAl Viro * @path: pointer to struct path to fill 205816f18200SJosef 'Jeff' Sipek */ 205916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 206016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2061e0a01249SAl Viro struct path *path) 206216f18200SJosef 'Jeff' Sipek { 2063e0a01249SAl Viro struct nameidata nd; 2064e0a01249SAl Viro int err; 2065e0a01249SAl Viro nd.root.dentry = dentry; 2066e0a01249SAl Viro nd.root.mnt = mnt; 2067e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20685b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2069e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2070e0a01249SAl Viro if (!err) 2071e0a01249SAl Viro *path = nd.path; 2072e0a01249SAl Viro return err; 207316f18200SJosef 'Jeff' Sipek } 20744d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 207516f18200SJosef 'Jeff' Sipek 2076057f6c01SJames Morris /* 2077057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2078057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2079057f6c01SJames Morris * SMP-safe. 2080057f6c01SJames Morris */ 2081a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 20821da177e4SLinus Torvalds { 208372bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 20841da177e4SLinus Torvalds } 20851da177e4SLinus Torvalds 2086eead1911SChristoph Hellwig /** 2087a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2088eead1911SChristoph Hellwig * @name: pathname component to lookup 2089eead1911SChristoph Hellwig * @base: base directory to lookup from 2090eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2091eead1911SChristoph Hellwig * 2092a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2093a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2094eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2095eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2096eead1911SChristoph Hellwig */ 2097057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2098057f6c01SJames Morris { 2099057f6c01SJames Morris struct qstr this; 21006a96ba54SAl Viro unsigned int c; 2101cda309deSMiklos Szeredi int err; 2102057f6c01SJames Morris 21032f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21042f9092e1SDavid Woodhouse 21056a96ba54SAl Viro this.name = name; 21066a96ba54SAl Viro this.len = len; 21070145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21086a96ba54SAl Viro if (!len) 21096a96ba54SAl Viro return ERR_PTR(-EACCES); 21106a96ba54SAl Viro 211121d8a15aSAl Viro if (unlikely(name[0] == '.')) { 211221d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 211321d8a15aSAl Viro return ERR_PTR(-EACCES); 211421d8a15aSAl Viro } 211521d8a15aSAl Viro 21166a96ba54SAl Viro while (len--) { 21176a96ba54SAl Viro c = *(const unsigned char *)name++; 21186a96ba54SAl Viro if (c == '/' || c == '\0') 21196a96ba54SAl Viro return ERR_PTR(-EACCES); 21206a96ba54SAl Viro } 21215a202bcdSAl Viro /* 21225a202bcdSAl Viro * See if the low-level filesystem might want 21235a202bcdSAl Viro * to use its own hash.. 21245a202bcdSAl Viro */ 21255a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2126da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21275a202bcdSAl Viro if (err < 0) 21285a202bcdSAl Viro return ERR_PTR(err); 21295a202bcdSAl Viro } 2130eead1911SChristoph Hellwig 2131cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2132cda309deSMiklos Szeredi if (err) 2133cda309deSMiklos Szeredi return ERR_PTR(err); 2134cda309deSMiklos Szeredi 213572bd866aSAl Viro return __lookup_hash(&this, base, 0); 2136057f6c01SJames Morris } 21374d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2138057f6c01SJames Morris 21391fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21401fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21411da177e4SLinus Torvalds { 21422d8f3038SAl Viro struct nameidata nd; 214391a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21441da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21451da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21462d8f3038SAl Viro 21472d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21482d8f3038SAl Viro 2149873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21501da177e4SLinus Torvalds putname(tmp); 21512d8f3038SAl Viro if (!err) 21522d8f3038SAl Viro *path = nd.path; 21531da177e4SLinus Torvalds } 21541da177e4SLinus Torvalds return err; 21551da177e4SLinus Torvalds } 21561da177e4SLinus Torvalds 21571fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21581fa1e7f6SAndy Whitcroft struct path *path) 21591fa1e7f6SAndy Whitcroft { 2160f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21611fa1e7f6SAndy Whitcroft } 21624d359507SAl Viro EXPORT_SYMBOL(user_path_at); 21631fa1e7f6SAndy Whitcroft 2164873f1eedSJeff Layton /* 2165873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2166873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2167873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2168873f1eedSJeff Layton * path-walking is complete. 2169873f1eedSJeff Layton */ 217091a27b2aSJeff Layton static struct filename * 21719e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 21729e790bd6SJeff Layton unsigned int flags) 21732ad94ae6SAl Viro { 217491a27b2aSJeff Layton struct filename *s = getname(path); 21752ad94ae6SAl Viro int error; 21762ad94ae6SAl Viro 21779e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 21789e790bd6SJeff Layton flags &= LOOKUP_REVAL; 21799e790bd6SJeff Layton 21802ad94ae6SAl Viro if (IS_ERR(s)) 218191a27b2aSJeff Layton return s; 21822ad94ae6SAl Viro 21839e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 218491a27b2aSJeff Layton if (error) { 21852ad94ae6SAl Viro putname(s); 218691a27b2aSJeff Layton return ERR_PTR(error); 218791a27b2aSJeff Layton } 21882ad94ae6SAl Viro 218991a27b2aSJeff Layton return s; 21902ad94ae6SAl Viro } 21912ad94ae6SAl Viro 21928033426eSJeff Layton /** 2193197df04cSAl Viro * mountpoint_last - look up last component for umount 21948033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 21958033426eSJeff Layton * @path: pointer to container for result 21968033426eSJeff Layton * 21978033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 21988033426eSJeff Layton * need to resolve the path without doing any revalidation. 21998033426eSJeff Layton * 22008033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22018033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22028033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22038033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22048033426eSJeff Layton * bogus and it doesn't exist. 22058033426eSJeff Layton * 22068033426eSJeff Layton * Returns: 22078033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22088033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22098033426eSJeff Layton * put in this case. 22108033426eSJeff Layton * 22118033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22128033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22138033426eSJeff Layton * The nd->path reference will also be put. 22148033426eSJeff Layton * 22158033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22168033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22178033426eSJeff Layton * to the link, and nd->path will *not* be put. 22188033426eSJeff Layton */ 22198033426eSJeff Layton static int 2220197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22218033426eSJeff Layton { 22228033426eSJeff Layton int error = 0; 22238033426eSJeff Layton struct dentry *dentry; 22248033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22258033426eSJeff Layton 222635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 222735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 222835759521SAl Viro if (unlazy_walk(nd, NULL)) { 22298033426eSJeff Layton error = -ECHILD; 223035759521SAl Viro goto out; 223135759521SAl Viro } 22328033426eSJeff Layton } 22338033426eSJeff Layton 22348033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22358033426eSJeff Layton 22368033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22378033426eSJeff Layton error = handle_dots(nd, nd->last_type); 223835759521SAl Viro if (error) 223935759521SAl Viro goto out; 22408033426eSJeff Layton dentry = dget(nd->path.dentry); 224135759521SAl Viro goto done; 22428033426eSJeff Layton } 22438033426eSJeff Layton 22448033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22458033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22468033426eSJeff Layton if (!dentry) { 22478033426eSJeff Layton /* 22488033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22498033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22508033426eSJeff Layton * path doesn't actually point to a mounted dentry. 22518033426eSJeff Layton */ 22528033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22538033426eSJeff Layton if (!dentry) { 22548033426eSJeff Layton error = -ENOMEM; 2255bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 225635759521SAl Viro goto out; 22578033426eSJeff Layton } 225835759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 225935759521SAl Viro error = PTR_ERR(dentry); 2260bcceeebaSDave Jones if (IS_ERR(dentry)) { 2261bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 226235759521SAl Viro goto out; 22638033426eSJeff Layton } 2264bcceeebaSDave Jones } 22658033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 22668033426eSJeff Layton 226735759521SAl Viro done: 226822213318SAl Viro if (!dentry->d_inode || d_is_negative(dentry)) { 22698033426eSJeff Layton error = -ENOENT; 22708033426eSJeff Layton dput(dentry); 227135759521SAl Viro goto out; 227235759521SAl Viro } 22738033426eSJeff Layton path->dentry = dentry; 2274295dc39dSVasily Averin path->mnt = nd->path.mnt; 2275b18825a7SDavid Howells if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) 22768033426eSJeff Layton return 1; 2277295dc39dSVasily Averin mntget(path->mnt); 22788033426eSJeff Layton follow_mount(path); 227935759521SAl Viro error = 0; 228035759521SAl Viro out: 22818033426eSJeff Layton terminate_walk(nd); 22828033426eSJeff Layton return error; 22838033426eSJeff Layton } 22848033426eSJeff Layton 22858033426eSJeff Layton /** 2286197df04cSAl Viro * path_mountpoint - look up a path to be umounted 22878033426eSJeff Layton * @dfd: directory file descriptor to start walk from 22888033426eSJeff Layton * @name: full pathname to walk 2289606d6fe3SRandy Dunlap * @path: pointer to container for result 22908033426eSJeff Layton * @flags: lookup flags 22918033426eSJeff Layton * 22928033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2293606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 22948033426eSJeff Layton */ 22958033426eSJeff Layton static int 2296197df04cSAl Viro path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) 22978033426eSJeff Layton { 22988033426eSJeff Layton struct file *base = NULL; 22998033426eSJeff Layton struct nameidata nd; 23008033426eSJeff Layton int err; 23018033426eSJeff Layton 23028033426eSJeff Layton err = path_init(dfd, name, flags | LOOKUP_PARENT, &nd, &base); 23038033426eSJeff Layton if (unlikely(err)) 23048033426eSJeff Layton return err; 23058033426eSJeff Layton 23068033426eSJeff Layton current->total_link_count = 0; 23078033426eSJeff Layton err = link_path_walk(name, &nd); 23088033426eSJeff Layton if (err) 23098033426eSJeff Layton goto out; 23108033426eSJeff Layton 2311197df04cSAl Viro err = mountpoint_last(&nd, path); 23128033426eSJeff Layton while (err > 0) { 23138033426eSJeff Layton void *cookie; 23148033426eSJeff Layton struct path link = *path; 23158033426eSJeff Layton err = may_follow_link(&link, &nd); 23168033426eSJeff Layton if (unlikely(err)) 23178033426eSJeff Layton break; 23188033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 23198033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 23208033426eSJeff Layton if (err) 23218033426eSJeff Layton break; 2322197df04cSAl Viro err = mountpoint_last(&nd, path); 23238033426eSJeff Layton put_link(&nd, &link, cookie); 23248033426eSJeff Layton } 23258033426eSJeff Layton out: 23268033426eSJeff Layton if (base) 23278033426eSJeff Layton fput(base); 23288033426eSJeff Layton 23298033426eSJeff Layton if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT)) 23308033426eSJeff Layton path_put(&nd.root); 23318033426eSJeff Layton 23328033426eSJeff Layton return err; 23338033426eSJeff Layton } 23348033426eSJeff Layton 23352d864651SAl Viro static int 23362d864651SAl Viro filename_mountpoint(int dfd, struct filename *s, struct path *path, 23372d864651SAl Viro unsigned int flags) 23382d864651SAl Viro { 23392d864651SAl Viro int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); 23402d864651SAl Viro if (unlikely(error == -ECHILD)) 23412d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags); 23422d864651SAl Viro if (unlikely(error == -ESTALE)) 23432d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); 23442d864651SAl Viro if (likely(!error)) 23452d864651SAl Viro audit_inode(s, path->dentry, 0); 23462d864651SAl Viro return error; 23472d864651SAl Viro } 23482d864651SAl Viro 23498033426eSJeff Layton /** 2350197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 23518033426eSJeff Layton * @dfd: directory file descriptor 23528033426eSJeff Layton * @name: pathname from userland 23538033426eSJeff Layton * @flags: lookup flags 23548033426eSJeff Layton * @path: pointer to container to hold result 23558033426eSJeff Layton * 23568033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23578033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23588033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23598033426eSJeff Layton * and avoid revalidating the last component. 23608033426eSJeff Layton * 23618033426eSJeff Layton * Returns 0 and populates "path" on success. 23628033426eSJeff Layton */ 23638033426eSJeff Layton int 2364197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 23658033426eSJeff Layton struct path *path) 23668033426eSJeff Layton { 23678033426eSJeff Layton struct filename *s = getname(name); 23688033426eSJeff Layton int error; 23698033426eSJeff Layton if (IS_ERR(s)) 23708033426eSJeff Layton return PTR_ERR(s); 23712d864651SAl Viro error = filename_mountpoint(dfd, s, path, flags); 23728033426eSJeff Layton putname(s); 23738033426eSJeff Layton return error; 23748033426eSJeff Layton } 23758033426eSJeff Layton 23762d864651SAl Viro int 23772d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 23782d864651SAl Viro unsigned int flags) 23792d864651SAl Viro { 23802d864651SAl Viro struct filename s = {.name = name}; 23812d864651SAl Viro return filename_mountpoint(dfd, &s, path, flags); 23822d864651SAl Viro } 23832d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 23842d864651SAl Viro 23851da177e4SLinus Torvalds /* 23861da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 23871da177e4SLinus Torvalds * minimal. 23881da177e4SLinus Torvalds */ 23891da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 23901da177e4SLinus Torvalds { 23918e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2392da9592edSDavid Howells 23931da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 23941da177e4SLinus Torvalds return 0; 23958e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 23961da177e4SLinus Torvalds return 0; 23978e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 23981da177e4SLinus Torvalds return 0; 239923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24001da177e4SLinus Torvalds } 24011da177e4SLinus Torvalds 24021da177e4SLinus Torvalds /* 24031da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24041da177e4SLinus Torvalds * whether the type of victim is right. 24051da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24061da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24071da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24081da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24091da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24101da177e4SLinus Torvalds * a. be owner of dir, or 24111da177e4SLinus Torvalds * b. be owner of victim, or 24121da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24131da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24141da177e4SLinus Torvalds * links pointing to it. 24151da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24161da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24171da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24181da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24191da177e4SLinus Torvalds * nfs_async_unlink(). 24201da177e4SLinus Torvalds */ 2421b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24221da177e4SLinus Torvalds { 2423b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24241da177e4SLinus Torvalds int error; 24251da177e4SLinus Torvalds 2426b18825a7SDavid Howells if (d_is_negative(victim)) 24271da177e4SLinus Torvalds return -ENOENT; 2428b18825a7SDavid Howells BUG_ON(!inode); 24291da177e4SLinus Torvalds 24301da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24314fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24321da177e4SLinus Torvalds 2433f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24341da177e4SLinus Torvalds if (error) 24351da177e4SLinus Torvalds return error; 24361da177e4SLinus Torvalds if (IS_APPEND(dir)) 24371da177e4SLinus Torvalds return -EPERM; 2438b18825a7SDavid Howells 2439b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2440b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24411da177e4SLinus Torvalds return -EPERM; 24421da177e4SLinus Torvalds if (isdir) { 244344b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24441da177e4SLinus Torvalds return -ENOTDIR; 24451da177e4SLinus Torvalds if (IS_ROOT(victim)) 24461da177e4SLinus Torvalds return -EBUSY; 244744b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24481da177e4SLinus Torvalds return -EISDIR; 24491da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24501da177e4SLinus Torvalds return -ENOENT; 24511da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24521da177e4SLinus Torvalds return -EBUSY; 24531da177e4SLinus Torvalds return 0; 24541da177e4SLinus Torvalds } 24551da177e4SLinus Torvalds 24561da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24571da177e4SLinus Torvalds * dir. 24581da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24591da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24601da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24611da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24621da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24631da177e4SLinus Torvalds */ 2464a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24651da177e4SLinus Torvalds { 246614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 24671da177e4SLinus Torvalds if (child->d_inode) 24681da177e4SLinus Torvalds return -EEXIST; 24691da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24701da177e4SLinus Torvalds return -ENOENT; 2471f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24721da177e4SLinus Torvalds } 24731da177e4SLinus Torvalds 24741da177e4SLinus Torvalds /* 24751da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24761da177e4SLinus Torvalds */ 24771da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24781da177e4SLinus Torvalds { 24791da177e4SLinus Torvalds struct dentry *p; 24801da177e4SLinus Torvalds 24811da177e4SLinus Torvalds if (p1 == p2) { 2482f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 24831da177e4SLinus Torvalds return NULL; 24841da177e4SLinus Torvalds } 24851da177e4SLinus Torvalds 2486a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 24871da177e4SLinus Torvalds 2488e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2489e2761a11SOGAWA Hirofumi if (p) { 2490f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2491f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 24921da177e4SLinus Torvalds return p; 24931da177e4SLinus Torvalds } 24941da177e4SLinus Torvalds 2495e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2496e2761a11SOGAWA Hirofumi if (p) { 2497f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2498f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 24991da177e4SLinus Torvalds return p; 25001da177e4SLinus Torvalds } 25011da177e4SLinus Torvalds 2502f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2503f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25041da177e4SLinus Torvalds return NULL; 25051da177e4SLinus Torvalds } 25064d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25071da177e4SLinus Torvalds 25081da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25091da177e4SLinus Torvalds { 25101b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25111da177e4SLinus Torvalds if (p1 != p2) { 25121b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2513a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25141da177e4SLinus Torvalds } 25151da177e4SLinus Torvalds } 25164d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25171da177e4SLinus Torvalds 25184acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2519312b63fbSAl Viro bool want_excl) 25201da177e4SLinus Torvalds { 2521a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25221da177e4SLinus Torvalds if (error) 25231da177e4SLinus Torvalds return error; 25241da177e4SLinus Torvalds 2525acfa4380SAl Viro if (!dir->i_op->create) 25261da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25271da177e4SLinus Torvalds mode &= S_IALLUGO; 25281da177e4SLinus Torvalds mode |= S_IFREG; 25291da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25301da177e4SLinus Torvalds if (error) 25311da177e4SLinus Torvalds return error; 2532312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2533a74574aaSStephen Smalley if (!error) 2534f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25351da177e4SLinus Torvalds return error; 25361da177e4SLinus Torvalds } 25374d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25381da177e4SLinus Torvalds 253973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25401da177e4SLinus Torvalds { 25413fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25421da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25431da177e4SLinus Torvalds int error; 25441da177e4SLinus Torvalds 2545bcda7652SAl Viro /* O_PATH? */ 2546bcda7652SAl Viro if (!acc_mode) 2547bcda7652SAl Viro return 0; 2548bcda7652SAl Viro 25491da177e4SLinus Torvalds if (!inode) 25501da177e4SLinus Torvalds return -ENOENT; 25511da177e4SLinus Torvalds 2552c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2553c8fe8f30SChristoph Hellwig case S_IFLNK: 25541da177e4SLinus Torvalds return -ELOOP; 2555c8fe8f30SChristoph Hellwig case S_IFDIR: 2556c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25571da177e4SLinus Torvalds return -EISDIR; 2558c8fe8f30SChristoph Hellwig break; 2559c8fe8f30SChristoph Hellwig case S_IFBLK: 2560c8fe8f30SChristoph Hellwig case S_IFCHR: 25613fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25621da177e4SLinus Torvalds return -EACCES; 2563c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2564c8fe8f30SChristoph Hellwig case S_IFIFO: 2565c8fe8f30SChristoph Hellwig case S_IFSOCK: 25661da177e4SLinus Torvalds flag &= ~O_TRUNC; 2567c8fe8f30SChristoph Hellwig break; 25684a3fd211SDave Hansen } 2569b41572e9SDave Hansen 25703fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2571b41572e9SDave Hansen if (error) 2572b41572e9SDave Hansen return error; 25736146f0d5SMimi Zohar 25741da177e4SLinus Torvalds /* 25751da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25761da177e4SLinus Torvalds */ 25771da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25788737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 25797715b521SAl Viro return -EPERM; 25801da177e4SLinus Torvalds if (flag & O_TRUNC) 25817715b521SAl Viro return -EPERM; 25821da177e4SLinus Torvalds } 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 25852e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 25867715b521SAl Viro return -EPERM; 25871da177e4SLinus Torvalds 2588f3c7691eSJ. Bruce Fields return 0; 25897715b521SAl Viro } 25907715b521SAl Viro 2591e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 25927715b521SAl Viro { 2593e1181ee6SJeff Layton struct path *path = &filp->f_path; 25947715b521SAl Viro struct inode *inode = path->dentry->d_inode; 25957715b521SAl Viro int error = get_write_access(inode); 25961da177e4SLinus Torvalds if (error) 25977715b521SAl Viro return error; 25981da177e4SLinus Torvalds /* 25991da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26001da177e4SLinus Torvalds */ 2601d7a06983SJeff Layton error = locks_verify_locked(filp); 2602be6d3e56SKentaro Takeda if (!error) 2603ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26041da177e4SLinus Torvalds if (!error) { 26057715b521SAl Viro error = do_truncate(path->dentry, 0, 2606d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2607e1181ee6SJeff Layton filp); 26081da177e4SLinus Torvalds } 26091da177e4SLinus Torvalds put_write_access(inode); 2610acd0c935SMimi Zohar return error; 26111da177e4SLinus Torvalds } 26121da177e4SLinus Torvalds 2613d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2614d57999e1SDave Hansen { 26158a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26168a5e929dSAl Viro flag--; 2617d57999e1SDave Hansen return flag; 2618d57999e1SDave Hansen } 2619d57999e1SDave Hansen 2620d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2621d18e9008SMiklos Szeredi { 2622d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2623d18e9008SMiklos Szeredi if (error) 2624d18e9008SMiklos Szeredi return error; 2625d18e9008SMiklos Szeredi 2626d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2627d18e9008SMiklos Szeredi if (error) 2628d18e9008SMiklos Szeredi return error; 2629d18e9008SMiklos Szeredi 2630d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2631d18e9008SMiklos Szeredi } 2632d18e9008SMiklos Szeredi 26331acf0af9SDavid Howells /* 26341acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26351acf0af9SDavid Howells * dentry. 26361acf0af9SDavid Howells * 26371acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26381acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26391acf0af9SDavid Howells * 26401acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26411acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26421acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26431acf0af9SDavid Howells * 26441acf0af9SDavid Howells * Returns an error code otherwise. 26451acf0af9SDavid Howells */ 26462675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 264730d90494SAl Viro struct path *path, struct file *file, 2648015c3bbcSMiklos Szeredi const struct open_flags *op, 264964894cf8SAl Viro bool got_write, bool need_lookup, 265047237687SAl Viro int *opened) 2651d18e9008SMiklos Szeredi { 2652d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2653d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2654d18e9008SMiklos Szeredi umode_t mode; 2655d18e9008SMiklos Szeredi int error; 2656d18e9008SMiklos Szeredi int acc_mode; 2657d18e9008SMiklos Szeredi int create_error = 0; 2658d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2659116cc022SMiklos Szeredi bool excl; 2660d18e9008SMiklos Szeredi 2661d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2662d18e9008SMiklos Szeredi 2663d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2664d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26652675a4ebSAl Viro error = -ENOENT; 2666d18e9008SMiklos Szeredi goto out; 2667d18e9008SMiklos Szeredi } 2668d18e9008SMiklos Szeredi 266962b259d8SMiklos Szeredi mode = op->mode; 2670d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2671d18e9008SMiklos Szeredi mode &= ~current_umask(); 2672d18e9008SMiklos Szeredi 2673116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2674116cc022SMiklos Szeredi if (excl) 2675d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2676d18e9008SMiklos Szeredi 2677d18e9008SMiklos Szeredi /* 2678d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2679d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2680d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2681d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2682d18e9008SMiklos Szeredi * 2683d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2684d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2685d18e9008SMiklos Szeredi */ 268664894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 268764894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 268864894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2689d18e9008SMiklos Szeredi /* 2690d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2691d18e9008SMiklos Szeredi * back to lookup + open 2692d18e9008SMiklos Szeredi */ 2693d18e9008SMiklos Szeredi goto no_open; 2694d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2695d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 269664894cf8SAl Viro create_error = -EROFS; 2697d18e9008SMiklos Szeredi goto no_open; 2698d18e9008SMiklos Szeredi } else { 2699d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 270064894cf8SAl Viro create_error = -EROFS; 2701d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2702d18e9008SMiklos Szeredi } 2703d18e9008SMiklos Szeredi } 2704d18e9008SMiklos Szeredi 2705d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 270638227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2707d18e9008SMiklos Szeredi if (error) { 2708d18e9008SMiklos Szeredi create_error = error; 2709d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2710d18e9008SMiklos Szeredi goto no_open; 2711d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2712d18e9008SMiklos Szeredi } 2713d18e9008SMiklos Szeredi } 2714d18e9008SMiklos Szeredi 2715d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2716d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2717d18e9008SMiklos Szeredi 271830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 271930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 272030d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 272147237687SAl Viro opened); 2722d9585277SAl Viro if (error < 0) { 2723d9585277SAl Viro if (create_error && error == -ENOENT) 2724d9585277SAl Viro error = create_error; 2725d18e9008SMiklos Szeredi goto out; 2726d18e9008SMiklos Szeredi } 2727d18e9008SMiklos Szeredi 2728d9585277SAl Viro if (error) { /* returned 1, that is */ 272930d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27302675a4ebSAl Viro error = -EIO; 2731d18e9008SMiklos Szeredi goto out; 2732d18e9008SMiklos Szeredi } 273330d90494SAl Viro if (file->f_path.dentry) { 2734d18e9008SMiklos Szeredi dput(dentry); 273530d90494SAl Viro dentry = file->f_path.dentry; 2736d18e9008SMiklos Szeredi } 273703da633aSAl Viro if (*opened & FILE_CREATED) 273803da633aSAl Viro fsnotify_create(dir, dentry); 273903da633aSAl Viro if (!dentry->d_inode) { 274003da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 274103da633aSAl Viro if (create_error) { 274262b2ce96SSage Weil error = create_error; 274362b2ce96SSage Weil goto out; 274462b2ce96SSage Weil } 274503da633aSAl Viro } else { 274603da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 274703da633aSAl Viro error = -EEXIST; 274803da633aSAl Viro goto out; 274903da633aSAl Viro } 275003da633aSAl Viro } 2751d18e9008SMiklos Szeredi goto looked_up; 2752d18e9008SMiklos Szeredi } 2753d18e9008SMiklos Szeredi 2754d18e9008SMiklos Szeredi /* 2755d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2756d18e9008SMiklos Szeredi * here. 2757d18e9008SMiklos Szeredi */ 275803da633aSAl Viro acc_mode = op->acc_mode; 275903da633aSAl Viro if (*opened & FILE_CREATED) { 276003da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 276103da633aSAl Viro fsnotify_create(dir, dentry); 276203da633aSAl Viro acc_mode = MAY_OPEN; 276303da633aSAl Viro } 27642675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27652675a4ebSAl Viro if (error) 27662675a4ebSAl Viro fput(file); 2767d18e9008SMiklos Szeredi 2768d18e9008SMiklos Szeredi out: 2769d18e9008SMiklos Szeredi dput(dentry); 27702675a4ebSAl Viro return error; 2771d18e9008SMiklos Szeredi 2772d18e9008SMiklos Szeredi no_open: 2773d18e9008SMiklos Szeredi if (need_lookup) { 277472bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2775d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27762675a4ebSAl Viro return PTR_ERR(dentry); 2777d18e9008SMiklos Szeredi 2778d18e9008SMiklos Szeredi if (create_error) { 2779d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2780d18e9008SMiklos Szeredi 27812675a4ebSAl Viro error = create_error; 2782d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2783d18e9008SMiklos Szeredi if (!dentry->d_inode) 2784d18e9008SMiklos Szeredi goto out; 2785d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2786d18e9008SMiklos Szeredi goto out; 2787d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2788d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2789d18e9008SMiklos Szeredi goto out; 2790d18e9008SMiklos Szeredi } 2791d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2792d18e9008SMiklos Szeredi } 2793d18e9008SMiklos Szeredi } 2794d18e9008SMiklos Szeredi looked_up: 2795d18e9008SMiklos Szeredi path->dentry = dentry; 2796d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 27972675a4ebSAl Viro return 1; 2798d18e9008SMiklos Szeredi } 2799d18e9008SMiklos Szeredi 280031e6b01fSNick Piggin /* 28011acf0af9SDavid Howells * Look up and maybe create and open the last component. 2802d58ffd35SMiklos Szeredi * 2803d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2804d58ffd35SMiklos Szeredi * 28051acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28061acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28071acf0af9SDavid Howells * 28081acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28091acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28101acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28111acf0af9SDavid Howells * specified then a negative dentry may be returned. 28121acf0af9SDavid Howells * 28131acf0af9SDavid Howells * An error code is returned otherwise. 28141acf0af9SDavid Howells * 28151acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28161acf0af9SDavid Howells * cleared otherwise prior to returning. 2817d58ffd35SMiklos Szeredi */ 28182675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 281930d90494SAl Viro struct file *file, 2820d58ffd35SMiklos Szeredi const struct open_flags *op, 282164894cf8SAl Viro bool got_write, int *opened) 2822d58ffd35SMiklos Szeredi { 2823d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 282454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2825d58ffd35SMiklos Szeredi struct dentry *dentry; 2826d58ffd35SMiklos Szeredi int error; 282754ef4872SMiklos Szeredi bool need_lookup; 2828d58ffd35SMiklos Szeredi 282947237687SAl Viro *opened &= ~FILE_CREATED; 2830201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2831d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28322675a4ebSAl Viro return PTR_ERR(dentry); 2833d58ffd35SMiklos Szeredi 2834d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2835d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2836d18e9008SMiklos Szeredi goto out_no_open; 2837d18e9008SMiklos Szeredi 2838d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 283964894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 284047237687SAl Viro need_lookup, opened); 2841d18e9008SMiklos Szeredi } 2842d18e9008SMiklos Szeredi 284354ef4872SMiklos Szeredi if (need_lookup) { 284454ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 284554ef4872SMiklos Szeredi 284672bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 284754ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28482675a4ebSAl Viro return PTR_ERR(dentry); 284954ef4872SMiklos Szeredi } 285054ef4872SMiklos Szeredi 2851d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2852d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2853d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2854d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2855d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2856d58ffd35SMiklos Szeredi /* 2857d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2858d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2859d58ffd35SMiklos Szeredi * the time when the file is created and when 2860d58ffd35SMiklos Szeredi * a permanent write count is taken through 2861015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2862d58ffd35SMiklos Szeredi */ 286364894cf8SAl Viro if (!got_write) { 286464894cf8SAl Viro error = -EROFS; 2865d58ffd35SMiklos Szeredi goto out_dput; 286664894cf8SAl Viro } 286747237687SAl Viro *opened |= FILE_CREATED; 2868d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2869d58ffd35SMiklos Szeredi if (error) 2870d58ffd35SMiklos Szeredi goto out_dput; 2871312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2872312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2873d58ffd35SMiklos Szeredi if (error) 2874d58ffd35SMiklos Szeredi goto out_dput; 2875d58ffd35SMiklos Szeredi } 2876d18e9008SMiklos Szeredi out_no_open: 2877d58ffd35SMiklos Szeredi path->dentry = dentry; 2878d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 28792675a4ebSAl Viro return 1; 2880d58ffd35SMiklos Szeredi 2881d58ffd35SMiklos Szeredi out_dput: 2882d58ffd35SMiklos Szeredi dput(dentry); 28832675a4ebSAl Viro return error; 2884d58ffd35SMiklos Szeredi } 2885d58ffd35SMiklos Szeredi 2886d58ffd35SMiklos Szeredi /* 2887fe2d35ffSAl Viro * Handle the last step of open() 288831e6b01fSNick Piggin */ 28892675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 289030d90494SAl Viro struct file *file, const struct open_flags *op, 2891669abf4eSJeff Layton int *opened, struct filename *name) 2892fb1cc555SAl Viro { 2893a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2894ca344a89SAl Viro int open_flag = op->open_flag; 289577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 289664894cf8SAl Viro bool got_write = false; 2897bcda7652SAl Viro int acc_mode = op->acc_mode; 2898a1eb3315SMiklos Szeredi struct inode *inode; 289977d660a8SMiklos Szeredi bool symlink_ok = false; 290016b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 290116b1c1cdSMiklos Szeredi bool retried = false; 290216c2cd71SAl Viro int error; 2903fb1cc555SAl Viro 2904c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2905c3e380b0SAl Viro nd->flags |= op->intent; 2906c3e380b0SAl Viro 2907bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2908fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2909fe2d35ffSAl Viro if (error) 29102675a4ebSAl Viro return error; 2911e83db167SMiklos Szeredi goto finish_open; 29121f36f774SAl Viro } 2913a2c36b45SAl Viro 2914ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2915fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2916fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2917bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 291877d660a8SMiklos Szeredi symlink_ok = true; 2919fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2920e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 292171574865SMiklos Szeredi if (likely(!error)) 292271574865SMiklos Szeredi goto finish_lookup; 292371574865SMiklos Szeredi 2924ce57dfc1SAl Viro if (error < 0) 29252675a4ebSAl Viro goto out; 2926a1eb3315SMiklos Szeredi 292737d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2928b6183df7SMiklos Szeredi } else { 2929fe2d35ffSAl Viro /* create side of things */ 2930a3fbbde7SAl Viro /* 2931b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2932b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2933b6183df7SMiklos Szeredi * about to look up 2934a3fbbde7SAl Viro */ 29359f1fafeeSAl Viro error = complete_walk(nd); 29369f1fafeeSAl Viro if (error) 29372675a4ebSAl Viro return error; 2938fe2d35ffSAl Viro 293933e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 294016c2cd71SAl Viro error = -EISDIR; 29411f36f774SAl Viro /* trailing slashes? */ 294231e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29432675a4ebSAl Viro goto out; 2944b6183df7SMiklos Szeredi } 29451f36f774SAl Viro 294616b1c1cdSMiklos Szeredi retry_lookup: 294764894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 294864894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 294964894cf8SAl Viro if (!error) 295064894cf8SAl Viro got_write = true; 295164894cf8SAl Viro /* 295264894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 295364894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 295464894cf8SAl Viro * dropping this one anyway. 295564894cf8SAl Viro */ 295664894cf8SAl Viro } 2957a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 295864894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2959fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2960fb1cc555SAl Viro 29612675a4ebSAl Viro if (error <= 0) { 29622675a4ebSAl Viro if (error) 2963d58ffd35SMiklos Szeredi goto out; 29646c0d46c4SAl Viro 296547237687SAl Viro if ((*opened & FILE_CREATED) || 2966496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 296777d660a8SMiklos Szeredi will_truncate = false; 2968d18e9008SMiklos Szeredi 2969adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2970d18e9008SMiklos Szeredi goto opened; 2971d18e9008SMiklos Szeredi } 2972d18e9008SMiklos Szeredi 297347237687SAl Viro if (*opened & FILE_CREATED) { 29749b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2975ca344a89SAl Viro open_flag &= ~O_TRUNC; 297677d660a8SMiklos Szeredi will_truncate = false; 2977bcda7652SAl Viro acc_mode = MAY_OPEN; 2978d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2979e83db167SMiklos Szeredi goto finish_open_created; 2980fb1cc555SAl Viro } 2981fb1cc555SAl Viro 2982fb1cc555SAl Viro /* 29833134f37eSJeff Layton * create/update audit record if it already exists. 2984fb1cc555SAl Viro */ 2985b18825a7SDavid Howells if (d_is_positive(path->dentry)) 2986adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 2987fb1cc555SAl Viro 2988d18e9008SMiklos Szeredi /* 2989d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2990d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2991d18e9008SMiklos Szeredi * necessary...) 2992d18e9008SMiklos Szeredi */ 299364894cf8SAl Viro if (got_write) { 2994d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 299564894cf8SAl Viro got_write = false; 2996d18e9008SMiklos Szeredi } 2997d18e9008SMiklos Szeredi 2998fb1cc555SAl Viro error = -EEXIST; 2999f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3000fb1cc555SAl Viro goto exit_dput; 3001fb1cc555SAl Viro 30029875cf80SDavid Howells error = follow_managed(path, nd->flags); 30039875cf80SDavid Howells if (error < 0) 3004fb1cc555SAl Viro goto exit_dput; 3005fb1cc555SAl Viro 3006a3fbbde7SAl Viro if (error) 3007a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3008a3fbbde7SAl Viro 3009decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3010decf3400SMiklos Szeredi inode = path->dentry->d_inode; 30115f5daac1SMiklos Szeredi finish_lookup: 30125f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 3013fb1cc555SAl Viro error = -ENOENT; 301422213318SAl Viro if (!inode || d_is_negative(path->dentry)) { 301554c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 30162675a4ebSAl Viro goto out; 301754c33e7fSMiklos Szeredi } 30189e67f361SAl Viro 3019b18825a7SDavid Howells if (should_follow_link(path->dentry, !symlink_ok)) { 3020d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3021d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 3022d45ea867SMiklos Szeredi error = -ECHILD; 30232675a4ebSAl Viro goto out; 3024d45ea867SMiklos Szeredi } 3025d45ea867SMiklos Szeredi } 3026d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 30272675a4ebSAl Viro return 1; 3028d45ea867SMiklos Szeredi } 3029fb1cc555SAl Viro 303016b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 3031fb1cc555SAl Viro path_to_nameidata(path, nd); 303216b1c1cdSMiklos Szeredi } else { 303316b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 303416b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 303516b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 303616b1c1cdSMiklos Szeredi 303716b1c1cdSMiklos Szeredi } 3038decf3400SMiklos Szeredi nd->inode = inode; 3039a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3040bc77daa7SAl Viro finish_open: 3041a3fbbde7SAl Viro error = complete_walk(nd); 304216b1c1cdSMiklos Szeredi if (error) { 304316b1c1cdSMiklos Szeredi path_put(&save_parent); 30442675a4ebSAl Viro return error; 304516b1c1cdSMiklos Szeredi } 3046bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3047fb1cc555SAl Viro error = -EISDIR; 304844b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 30492675a4ebSAl Viro goto out; 3050af2f5542SMiklos Szeredi error = -ENOTDIR; 305144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 30522675a4ebSAl Viro goto out; 30536c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 305477d660a8SMiklos Szeredi will_truncate = false; 30556c0d46c4SAl Viro 30560f9d1a10SAl Viro if (will_truncate) { 30570f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30580f9d1a10SAl Viro if (error) 30592675a4ebSAl Viro goto out; 306064894cf8SAl Viro got_write = true; 30610f9d1a10SAl Viro } 3062e83db167SMiklos Szeredi finish_open_created: 3063bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3064ca344a89SAl Viro if (error) 30652675a4ebSAl Viro goto out; 306630d90494SAl Viro file->f_path.mnt = nd->path.mnt; 306730d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 306830d90494SAl Viro if (error) { 306930d90494SAl Viro if (error == -EOPENSTALE) 3070f60dc3dbSMiklos Szeredi goto stale_open; 3071015c3bbcSMiklos Szeredi goto out; 3072f60dc3dbSMiklos Szeredi } 3073a8277b9bSMiklos Szeredi opened: 30742675a4ebSAl Viro error = open_check_o_direct(file); 3075015c3bbcSMiklos Szeredi if (error) 3076015c3bbcSMiklos Szeredi goto exit_fput; 30772675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 3078aa4caadbSMiklos Szeredi if (error) 3079aa4caadbSMiklos Szeredi goto exit_fput; 3080aa4caadbSMiklos Szeredi 30810f9d1a10SAl Viro if (will_truncate) { 30822675a4ebSAl Viro error = handle_truncate(file); 3083aa4caadbSMiklos Szeredi if (error) 3084aa4caadbSMiklos Szeredi goto exit_fput; 30850f9d1a10SAl Viro } 3086ca344a89SAl Viro out: 308764894cf8SAl Viro if (got_write) 30880f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 308916b1c1cdSMiklos Szeredi path_put(&save_parent); 3090e276ae67SMiklos Szeredi terminate_walk(nd); 30912675a4ebSAl Viro return error; 3092fb1cc555SAl Viro 3093fb1cc555SAl Viro exit_dput: 3094fb1cc555SAl Viro path_put_conditional(path, nd); 3095ca344a89SAl Viro goto out; 3096015c3bbcSMiklos Szeredi exit_fput: 30972675a4ebSAl Viro fput(file); 30982675a4ebSAl Viro goto out; 3099015c3bbcSMiklos Szeredi 3100f60dc3dbSMiklos Szeredi stale_open: 3101f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3102f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3103f60dc3dbSMiklos Szeredi goto out; 3104f60dc3dbSMiklos Szeredi 3105f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3106f60dc3dbSMiklos Szeredi path_put(&nd->path); 3107f60dc3dbSMiklos Szeredi nd->path = save_parent; 3108f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3109f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3110f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 311164894cf8SAl Viro if (got_write) { 3112f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 311364894cf8SAl Viro got_write = false; 3114f60dc3dbSMiklos Szeredi } 3115f60dc3dbSMiklos Szeredi retried = true; 3116f60dc3dbSMiklos Szeredi goto retry_lookup; 3117fb1cc555SAl Viro } 3118fb1cc555SAl Viro 311960545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 312060545d0dSAl Viro struct nameidata *nd, int flags, 312160545d0dSAl Viro const struct open_flags *op, 312260545d0dSAl Viro struct file *file, int *opened) 312360545d0dSAl Viro { 312460545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 312560545d0dSAl Viro struct dentry *dentry, *child; 312660545d0dSAl Viro struct inode *dir; 312760545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 312860545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 312960545d0dSAl Viro if (unlikely(error)) 313060545d0dSAl Viro return error; 313160545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 313260545d0dSAl Viro if (unlikely(error)) 313360545d0dSAl Viro goto out; 313460545d0dSAl Viro /* we want directory to be writable */ 313560545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 313660545d0dSAl Viro if (error) 313760545d0dSAl Viro goto out2; 313860545d0dSAl Viro dentry = nd->path.dentry; 313960545d0dSAl Viro dir = dentry->d_inode; 314060545d0dSAl Viro if (!dir->i_op->tmpfile) { 314160545d0dSAl Viro error = -EOPNOTSUPP; 314260545d0dSAl Viro goto out2; 314360545d0dSAl Viro } 314460545d0dSAl Viro child = d_alloc(dentry, &name); 314560545d0dSAl Viro if (unlikely(!child)) { 314660545d0dSAl Viro error = -ENOMEM; 314760545d0dSAl Viro goto out2; 314860545d0dSAl Viro } 314960545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 315060545d0dSAl Viro nd->flags |= op->intent; 315160545d0dSAl Viro dput(nd->path.dentry); 315260545d0dSAl Viro nd->path.dentry = child; 315360545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 315460545d0dSAl Viro if (error) 315560545d0dSAl Viro goto out2; 315660545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 315760545d0dSAl Viro error = may_open(&nd->path, op->acc_mode, op->open_flag); 315860545d0dSAl Viro if (error) 315960545d0dSAl Viro goto out2; 316060545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 316160545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 316260545d0dSAl Viro if (error) 316360545d0dSAl Viro goto out2; 316460545d0dSAl Viro error = open_check_o_direct(file); 3165f4e0c30cSAl Viro if (error) { 316660545d0dSAl Viro fput(file); 3167f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3168f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3169f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3170f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3171f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3172f4e0c30cSAl Viro } 317360545d0dSAl Viro out2: 317460545d0dSAl Viro mnt_drop_write(nd->path.mnt); 317560545d0dSAl Viro out: 317660545d0dSAl Viro path_put(&nd->path); 317760545d0dSAl Viro return error; 317860545d0dSAl Viro } 317960545d0dSAl Viro 3180669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 318173d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 31821da177e4SLinus Torvalds { 3183fe2d35ffSAl Viro struct file *base = NULL; 318430d90494SAl Viro struct file *file; 31859850c056SAl Viro struct path path; 318647237687SAl Viro int opened = 0; 318713aab428SAl Viro int error; 318831e6b01fSNick Piggin 318930d90494SAl Viro file = get_empty_filp(); 31901afc99beSAl Viro if (IS_ERR(file)) 31911afc99beSAl Viro return file; 319231e6b01fSNick Piggin 319330d90494SAl Viro file->f_flags = op->open_flag; 319431e6b01fSNick Piggin 3195bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 319660545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 319760545d0dSAl Viro goto out; 319860545d0dSAl Viro } 319960545d0dSAl Viro 3200669abf4eSJeff Layton error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); 320131e6b01fSNick Piggin if (unlikely(error)) 32022675a4ebSAl Viro goto out; 320331e6b01fSNick Piggin 3204fe2d35ffSAl Viro current->total_link_count = 0; 3205669abf4eSJeff Layton error = link_path_walk(pathname->name, nd); 320631e6b01fSNick Piggin if (unlikely(error)) 32072675a4ebSAl Viro goto out; 32081da177e4SLinus Torvalds 32092675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 32102675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 32117b9337aaSNick Piggin struct path link = path; 3212def4af30SAl Viro void *cookie; 3213574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 321473d049a4SAl Viro path_put_conditional(&path, nd); 321573d049a4SAl Viro path_put(&nd->path); 32162675a4ebSAl Viro error = -ELOOP; 321740b39136SAl Viro break; 321840b39136SAl Viro } 3219800179c9SKees Cook error = may_follow_link(&link, nd); 3220800179c9SKees Cook if (unlikely(error)) 3221800179c9SKees Cook break; 322273d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 322373d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3224574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3225c3e380b0SAl Viro if (unlikely(error)) 32262675a4ebSAl Viro break; 32272675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3228574197e0SAl Viro put_link(nd, &link, cookie); 3229806b681cSAl Viro } 323010fa8e62SAl Viro out: 323173d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 323273d049a4SAl Viro path_put(&nd->root); 3233fe2d35ffSAl Viro if (base) 3234fe2d35ffSAl Viro fput(base); 32352675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32362675a4ebSAl Viro BUG_ON(!error); 323730d90494SAl Viro put_filp(file); 3238015c3bbcSMiklos Szeredi } 32392675a4ebSAl Viro if (unlikely(error)) { 32402675a4ebSAl Viro if (error == -EOPENSTALE) { 32412675a4ebSAl Viro if (flags & LOOKUP_RCU) 32422675a4ebSAl Viro error = -ECHILD; 32432675a4ebSAl Viro else 32442675a4ebSAl Viro error = -ESTALE; 32452675a4ebSAl Viro } 32462675a4ebSAl Viro file = ERR_PTR(error); 32472675a4ebSAl Viro } 32482675a4ebSAl Viro return file; 3249de459215SKirill Korotaev } 32501da177e4SLinus Torvalds 3251669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3252f9652e10SAl Viro const struct open_flags *op) 325313aab428SAl Viro { 325473d049a4SAl Viro struct nameidata nd; 3255f9652e10SAl Viro int flags = op->lookup_flags; 325613aab428SAl Viro struct file *filp; 325713aab428SAl Viro 325873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 325913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 326073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 326113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 326273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 326313aab428SAl Viro return filp; 326413aab428SAl Viro } 326513aab428SAl Viro 326673d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3267f9652e10SAl Viro const char *name, const struct open_flags *op) 326873d049a4SAl Viro { 326973d049a4SAl Viro struct nameidata nd; 327073d049a4SAl Viro struct file *file; 3271669abf4eSJeff Layton struct filename filename = { .name = name }; 3272f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 327373d049a4SAl Viro 327473d049a4SAl Viro nd.root.mnt = mnt; 327573d049a4SAl Viro nd.root.dentry = dentry; 327673d049a4SAl Viro 3277b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 327873d049a4SAl Viro return ERR_PTR(-ELOOP); 327973d049a4SAl Viro 3280669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); 328173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3282669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags); 328373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3284669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); 328573d049a4SAl Viro return file; 328673d049a4SAl Viro } 328773d049a4SAl Viro 32881ac12b4bSJeff Layton struct dentry *kern_path_create(int dfd, const char *pathname, 32891ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 32901da177e4SLinus Torvalds { 3291c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3292ed75e95dSAl Viro struct nameidata nd; 3293c30dabfeSJan Kara int err2; 32941ac12b4bSJeff Layton int error; 32951ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 32961ac12b4bSJeff Layton 32971ac12b4bSJeff Layton /* 32981ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 32991ac12b4bSJeff Layton * other flags passed in are ignored! 33001ac12b4bSJeff Layton */ 33011ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33021ac12b4bSJeff Layton 33031ac12b4bSJeff Layton error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); 3304ed75e95dSAl Viro if (error) 3305ed75e95dSAl Viro return ERR_PTR(error); 33061da177e4SLinus Torvalds 3307c663e5d8SChristoph Hellwig /* 3308c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3309c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3310c663e5d8SChristoph Hellwig */ 3311ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3312ed75e95dSAl Viro goto out; 3313ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3314ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3315c663e5d8SChristoph Hellwig 3316c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3317c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3318c663e5d8SChristoph Hellwig /* 3319c663e5d8SChristoph Hellwig * Do the final lookup. 3320c663e5d8SChristoph Hellwig */ 3321ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3322ed75e95dSAl Viro dentry = lookup_hash(&nd); 33231da177e4SLinus Torvalds if (IS_ERR(dentry)) 3324a8104a9fSAl Viro goto unlock; 3325c663e5d8SChristoph Hellwig 3326a8104a9fSAl Viro error = -EEXIST; 3327b18825a7SDavid Howells if (d_is_positive(dentry)) 3328a8104a9fSAl Viro goto fail; 3329b18825a7SDavid Howells 3330c663e5d8SChristoph Hellwig /* 3331c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3332c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3333c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3334c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3335c663e5d8SChristoph Hellwig */ 3336ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3337a8104a9fSAl Viro error = -ENOENT; 3338ed75e95dSAl Viro goto fail; 3339e9baf6e5SAl Viro } 3340c30dabfeSJan Kara if (unlikely(err2)) { 3341c30dabfeSJan Kara error = err2; 3342a8104a9fSAl Viro goto fail; 3343c30dabfeSJan Kara } 3344ed75e95dSAl Viro *path = nd.path; 3345e9baf6e5SAl Viro return dentry; 33461da177e4SLinus Torvalds fail: 3347a8104a9fSAl Viro dput(dentry); 3348a8104a9fSAl Viro dentry = ERR_PTR(error); 3349a8104a9fSAl Viro unlock: 3350dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3351c30dabfeSJan Kara if (!err2) 3352c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3353ed75e95dSAl Viro out: 3354dae6ad8fSAl Viro path_put(&nd.path); 3355ed75e95dSAl Viro return dentry; 3356dae6ad8fSAl Viro } 3357dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3358dae6ad8fSAl Viro 3359921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3360921a1650SAl Viro { 3361921a1650SAl Viro dput(dentry); 3362921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3363a8104a9fSAl Viro mnt_drop_write(path->mnt); 3364921a1650SAl Viro path_put(path); 3365921a1650SAl Viro } 3366921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3367921a1650SAl Viro 33681ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33691ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3370dae6ad8fSAl Viro { 337191a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3372dae6ad8fSAl Viro struct dentry *res; 3373dae6ad8fSAl Viro if (IS_ERR(tmp)) 3374dae6ad8fSAl Viro return ERR_CAST(tmp); 33751ac12b4bSJeff Layton res = kern_path_create(dfd, tmp->name, path, lookup_flags); 3376dae6ad8fSAl Viro putname(tmp); 3377dae6ad8fSAl Viro return res; 3378dae6ad8fSAl Viro } 3379dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3380dae6ad8fSAl Viro 33811a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 33821da177e4SLinus Torvalds { 3383a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 33841da177e4SLinus Torvalds 33851da177e4SLinus Torvalds if (error) 33861da177e4SLinus Torvalds return error; 33871da177e4SLinus Torvalds 3388975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 33891da177e4SLinus Torvalds return -EPERM; 33901da177e4SLinus Torvalds 3391acfa4380SAl Viro if (!dir->i_op->mknod) 33921da177e4SLinus Torvalds return -EPERM; 33931da177e4SLinus Torvalds 339408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 339508ce5f16SSerge E. Hallyn if (error) 339608ce5f16SSerge E. Hallyn return error; 339708ce5f16SSerge E. Hallyn 33981da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 33991da177e4SLinus Torvalds if (error) 34001da177e4SLinus Torvalds return error; 34011da177e4SLinus Torvalds 34021da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3403a74574aaSStephen Smalley if (!error) 3404f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34051da177e4SLinus Torvalds return error; 34061da177e4SLinus Torvalds } 34074d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34081da177e4SLinus Torvalds 3409f69aac00SAl Viro static int may_mknod(umode_t mode) 3410463c3197SDave Hansen { 3411463c3197SDave Hansen switch (mode & S_IFMT) { 3412463c3197SDave Hansen case S_IFREG: 3413463c3197SDave Hansen case S_IFCHR: 3414463c3197SDave Hansen case S_IFBLK: 3415463c3197SDave Hansen case S_IFIFO: 3416463c3197SDave Hansen case S_IFSOCK: 3417463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3418463c3197SDave Hansen return 0; 3419463c3197SDave Hansen case S_IFDIR: 3420463c3197SDave Hansen return -EPERM; 3421463c3197SDave Hansen default: 3422463c3197SDave Hansen return -EINVAL; 3423463c3197SDave Hansen } 3424463c3197SDave Hansen } 3425463c3197SDave Hansen 34268208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34272e4d0924SHeiko Carstens unsigned, dev) 34281da177e4SLinus Torvalds { 34291da177e4SLinus Torvalds struct dentry *dentry; 3430dae6ad8fSAl Viro struct path path; 3431dae6ad8fSAl Viro int error; 3432972567f1SJeff Layton unsigned int lookup_flags = 0; 34331da177e4SLinus Torvalds 34348e4bfca1SAl Viro error = may_mknod(mode); 34358e4bfca1SAl Viro if (error) 34368e4bfca1SAl Viro return error; 3437972567f1SJeff Layton retry: 3438972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3439dae6ad8fSAl Viro if (IS_ERR(dentry)) 3440dae6ad8fSAl Viro return PTR_ERR(dentry); 34412ad94ae6SAl Viro 3442dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3443ce3b0f8dSAl Viro mode &= ~current_umask(); 3444dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3445be6d3e56SKentaro Takeda if (error) 3446a8104a9fSAl Viro goto out; 34471da177e4SLinus Torvalds switch (mode & S_IFMT) { 34481da177e4SLinus Torvalds case 0: case S_IFREG: 3449312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34501da177e4SLinus Torvalds break; 34511da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3452dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34531da177e4SLinus Torvalds new_decode_dev(dev)); 34541da177e4SLinus Torvalds break; 34551da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3456dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34571da177e4SLinus Torvalds break; 34581da177e4SLinus Torvalds } 3459a8104a9fSAl Viro out: 3460921a1650SAl Viro done_path_create(&path, dentry); 3461972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3462972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3463972567f1SJeff Layton goto retry; 3464972567f1SJeff Layton } 34651da177e4SLinus Torvalds return error; 34661da177e4SLinus Torvalds } 34671da177e4SLinus Torvalds 34688208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34695590ff0dSUlrich Drepper { 34705590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34715590ff0dSUlrich Drepper } 34725590ff0dSUlrich Drepper 347318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 34741da177e4SLinus Torvalds { 3475a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34768de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34771da177e4SLinus Torvalds 34781da177e4SLinus Torvalds if (error) 34791da177e4SLinus Torvalds return error; 34801da177e4SLinus Torvalds 3481acfa4380SAl Viro if (!dir->i_op->mkdir) 34821da177e4SLinus Torvalds return -EPERM; 34831da177e4SLinus Torvalds 34841da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 34851da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 34861da177e4SLinus Torvalds if (error) 34871da177e4SLinus Torvalds return error; 34881da177e4SLinus Torvalds 34898de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 34908de52778SAl Viro return -EMLINK; 34918de52778SAl Viro 34921da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3493a74574aaSStephen Smalley if (!error) 3494f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 34951da177e4SLinus Torvalds return error; 34961da177e4SLinus Torvalds } 34974d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 34981da177e4SLinus Torvalds 3499a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35001da177e4SLinus Torvalds { 35016902d925SDave Hansen struct dentry *dentry; 3502dae6ad8fSAl Viro struct path path; 3503dae6ad8fSAl Viro int error; 3504b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35051da177e4SLinus Torvalds 3506b76d8b82SJeff Layton retry: 3507b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35086902d925SDave Hansen if (IS_ERR(dentry)) 3509dae6ad8fSAl Viro return PTR_ERR(dentry); 35106902d925SDave Hansen 3511dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3512ce3b0f8dSAl Viro mode &= ~current_umask(); 3513dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3514a8104a9fSAl Viro if (!error) 3515dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3516921a1650SAl Viro done_path_create(&path, dentry); 3517b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3518b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3519b76d8b82SJeff Layton goto retry; 3520b76d8b82SJeff Layton } 35211da177e4SLinus Torvalds return error; 35221da177e4SLinus Torvalds } 35231da177e4SLinus Torvalds 3524a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35255590ff0dSUlrich Drepper { 35265590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35275590ff0dSUlrich Drepper } 35285590ff0dSUlrich Drepper 35291da177e4SLinus Torvalds /* 3530a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3531c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3532a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3533a71905f0SSage Weil * then we drop the dentry now. 35341da177e4SLinus Torvalds * 35351da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35361da177e4SLinus Torvalds * do a 35371da177e4SLinus Torvalds * 35381da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35391da177e4SLinus Torvalds * return -EBUSY; 35401da177e4SLinus Torvalds * 35411da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35421da177e4SLinus Torvalds * that is still in use by something else.. 35431da177e4SLinus Torvalds */ 35441da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35451da177e4SLinus Torvalds { 35461da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35471da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 354898474236SWaiman Long if (dentry->d_lockref.count == 1) 35491da177e4SLinus Torvalds __d_drop(dentry); 35501da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35511da177e4SLinus Torvalds } 35524d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 35531da177e4SLinus Torvalds 35541da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35551da177e4SLinus Torvalds { 35561da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35571da177e4SLinus Torvalds 35581da177e4SLinus Torvalds if (error) 35591da177e4SLinus Torvalds return error; 35601da177e4SLinus Torvalds 3561acfa4380SAl Viro if (!dir->i_op->rmdir) 35621da177e4SLinus Torvalds return -EPERM; 35631da177e4SLinus Torvalds 35641d2ef590SAl Viro dget(dentry); 35651b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3566912dbc15SSage Weil 35671da177e4SLinus Torvalds error = -EBUSY; 35687af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 35697af1364fSEric W. Biederman goto out; 3570912dbc15SSage Weil if (d_mountpoint(dentry)) 3571912dbc15SSage Weil goto out; 3572912dbc15SSage Weil 35731da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3574912dbc15SSage Weil if (error) 3575912dbc15SSage Weil goto out; 3576912dbc15SSage Weil 35773cebde24SSage Weil shrink_dcache_parent(dentry); 35781da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3579912dbc15SSage Weil if (error) 3580912dbc15SSage Weil goto out; 3581912dbc15SSage Weil 35821da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3583d83c49f3SAl Viro dont_mount(dentry); 35841da177e4SLinus Torvalds 3585912dbc15SSage Weil out: 3586912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 35871d2ef590SAl Viro dput(dentry); 3588912dbc15SSage Weil if (!error) 3589912dbc15SSage Weil d_delete(dentry); 35901da177e4SLinus Torvalds return error; 35911da177e4SLinus Torvalds } 35924d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 35931da177e4SLinus Torvalds 35945590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 35951da177e4SLinus Torvalds { 35961da177e4SLinus Torvalds int error = 0; 359791a27b2aSJeff Layton struct filename *name; 35981da177e4SLinus Torvalds struct dentry *dentry; 35991da177e4SLinus Torvalds struct nameidata nd; 3600c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3601c6ee9206SJeff Layton retry: 3602c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 360391a27b2aSJeff Layton if (IS_ERR(name)) 360491a27b2aSJeff Layton return PTR_ERR(name); 36051da177e4SLinus Torvalds 36061da177e4SLinus Torvalds switch(nd.last_type) { 36071da177e4SLinus Torvalds case LAST_DOTDOT: 36081da177e4SLinus Torvalds error = -ENOTEMPTY; 36091da177e4SLinus Torvalds goto exit1; 36101da177e4SLinus Torvalds case LAST_DOT: 36111da177e4SLinus Torvalds error = -EINVAL; 36121da177e4SLinus Torvalds goto exit1; 36131da177e4SLinus Torvalds case LAST_ROOT: 36141da177e4SLinus Torvalds error = -EBUSY; 36151da177e4SLinus Torvalds goto exit1; 36161da177e4SLinus Torvalds } 36170612d9fbSOGAWA Hirofumi 36180612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3619c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3620c30dabfeSJan Kara if (error) 3621c30dabfeSJan Kara goto exit1; 36220612d9fbSOGAWA Hirofumi 36234ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 362449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36251da177e4SLinus Torvalds error = PTR_ERR(dentry); 36266902d925SDave Hansen if (IS_ERR(dentry)) 36276902d925SDave Hansen goto exit2; 3628e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3629e6bc45d6STheodore Ts'o error = -ENOENT; 3630e6bc45d6STheodore Ts'o goto exit3; 3631e6bc45d6STheodore Ts'o } 3632be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3633be6d3e56SKentaro Takeda if (error) 3634c30dabfeSJan Kara goto exit3; 36354ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 36360622753bSDave Hansen exit3: 36371da177e4SLinus Torvalds dput(dentry); 36386902d925SDave Hansen exit2: 36394ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3640c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 36411da177e4SLinus Torvalds exit1: 36421d957f9bSJan Blunck path_put(&nd.path); 36431da177e4SLinus Torvalds putname(name); 3644c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3645c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3646c6ee9206SJeff Layton goto retry; 3647c6ee9206SJeff Layton } 36481da177e4SLinus Torvalds return error; 36491da177e4SLinus Torvalds } 36501da177e4SLinus Torvalds 36513cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36525590ff0dSUlrich Drepper { 36535590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36545590ff0dSUlrich Drepper } 36555590ff0dSUlrich Drepper 3656b21996e3SJ. Bruce Fields /** 3657b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3658b21996e3SJ. Bruce Fields * @dir: parent directory 3659b21996e3SJ. Bruce Fields * @dentry: victim 3660b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3661b21996e3SJ. Bruce Fields * 3662b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3663b21996e3SJ. Bruce Fields * 3664b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3665b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3666b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3667b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3668b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3669b21996e3SJ. Bruce Fields * 3670b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3671b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3672b21996e3SJ. Bruce Fields * to be NFS exported. 3673b21996e3SJ. Bruce Fields */ 3674b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 36751da177e4SLinus Torvalds { 36769accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 36771da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 36781da177e4SLinus Torvalds 36791da177e4SLinus Torvalds if (error) 36801da177e4SLinus Torvalds return error; 36811da177e4SLinus Torvalds 3682acfa4380SAl Viro if (!dir->i_op->unlink) 36831da177e4SLinus Torvalds return -EPERM; 36841da177e4SLinus Torvalds 36859accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 36867af1364fSEric W. Biederman if (is_local_mountpoint(dentry) || d_mountpoint(dentry)) 36871da177e4SLinus Torvalds error = -EBUSY; 36881da177e4SLinus Torvalds else { 36891da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3690bec1052eSAl Viro if (!error) { 36915a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 36925a14696cSJ. Bruce Fields if (error) 3693b21996e3SJ. Bruce Fields goto out; 36941da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3695bec1052eSAl Viro if (!error) 3696d83c49f3SAl Viro dont_mount(dentry); 3697bec1052eSAl Viro } 36981da177e4SLinus Torvalds } 3699b21996e3SJ. Bruce Fields out: 37009accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37011da177e4SLinus Torvalds 37021da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37031da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37049accbb97SJ. Bruce Fields fsnotify_link_count(target); 37051da177e4SLinus Torvalds d_delete(dentry); 37061da177e4SLinus Torvalds } 37070eeca283SRobert Love 37081da177e4SLinus Torvalds return error; 37091da177e4SLinus Torvalds } 37104d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37111da177e4SLinus Torvalds 37121da177e4SLinus Torvalds /* 37131da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37141b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37151da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37161da177e4SLinus Torvalds * while waiting on the I/O. 37171da177e4SLinus Torvalds */ 37185590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37191da177e4SLinus Torvalds { 37202ad94ae6SAl Viro int error; 372191a27b2aSJeff Layton struct filename *name; 37221da177e4SLinus Torvalds struct dentry *dentry; 37231da177e4SLinus Torvalds struct nameidata nd; 37241da177e4SLinus Torvalds struct inode *inode = NULL; 3725b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37265d18f813SJeff Layton unsigned int lookup_flags = 0; 37275d18f813SJeff Layton retry: 37285d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 372991a27b2aSJeff Layton if (IS_ERR(name)) 373091a27b2aSJeff Layton return PTR_ERR(name); 37312ad94ae6SAl Viro 37321da177e4SLinus Torvalds error = -EISDIR; 37331da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 37341da177e4SLinus Torvalds goto exit1; 37350612d9fbSOGAWA Hirofumi 37360612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3737c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3738c30dabfeSJan Kara if (error) 3739c30dabfeSJan Kara goto exit1; 3740b21996e3SJ. Bruce Fields retry_deleg: 37414ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 374249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 37431da177e4SLinus Torvalds error = PTR_ERR(dentry); 37441da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37451da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 374650338b88STörök Edwin if (nd.last.name[nd.last.len]) 374750338b88STörök Edwin goto slashes; 37481da177e4SLinus Torvalds inode = dentry->d_inode; 3749b18825a7SDavid Howells if (d_is_negative(dentry)) 3750e6bc45d6STheodore Ts'o goto slashes; 37517de9c6eeSAl Viro ihold(inode); 3752be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3753be6d3e56SKentaro Takeda if (error) 3754c30dabfeSJan Kara goto exit2; 3755b21996e3SJ. Bruce Fields error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); 37561da177e4SLinus Torvalds exit2: 37571da177e4SLinus Torvalds dput(dentry); 37581da177e4SLinus Torvalds } 37594ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 37601da177e4SLinus Torvalds if (inode) 37611da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3762b21996e3SJ. Bruce Fields inode = NULL; 3763b21996e3SJ. Bruce Fields if (delegated_inode) { 37645a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3765b21996e3SJ. Bruce Fields if (!error) 3766b21996e3SJ. Bruce Fields goto retry_deleg; 3767b21996e3SJ. Bruce Fields } 3768c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 37691da177e4SLinus Torvalds exit1: 37701d957f9bSJan Blunck path_put(&nd.path); 37711da177e4SLinus Torvalds putname(name); 37725d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 37735d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 37745d18f813SJeff Layton inode = NULL; 37755d18f813SJeff Layton goto retry; 37765d18f813SJeff Layton } 37771da177e4SLinus Torvalds return error; 37781da177e4SLinus Torvalds 37791da177e4SLinus Torvalds slashes: 3780b18825a7SDavid Howells if (d_is_negative(dentry)) 3781b18825a7SDavid Howells error = -ENOENT; 378244b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3783b18825a7SDavid Howells error = -EISDIR; 3784b18825a7SDavid Howells else 3785b18825a7SDavid Howells error = -ENOTDIR; 37861da177e4SLinus Torvalds goto exit2; 37871da177e4SLinus Torvalds } 37881da177e4SLinus Torvalds 37892e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 37905590ff0dSUlrich Drepper { 37915590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 37925590ff0dSUlrich Drepper return -EINVAL; 37935590ff0dSUlrich Drepper 37945590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 37955590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 37965590ff0dSUlrich Drepper 37975590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 37985590ff0dSUlrich Drepper } 37995590ff0dSUlrich Drepper 38003480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38015590ff0dSUlrich Drepper { 38025590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38035590ff0dSUlrich Drepper } 38045590ff0dSUlrich Drepper 3805db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38061da177e4SLinus Torvalds { 3807a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38081da177e4SLinus Torvalds 38091da177e4SLinus Torvalds if (error) 38101da177e4SLinus Torvalds return error; 38111da177e4SLinus Torvalds 3812acfa4380SAl Viro if (!dir->i_op->symlink) 38131da177e4SLinus Torvalds return -EPERM; 38141da177e4SLinus Torvalds 38151da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38161da177e4SLinus Torvalds if (error) 38171da177e4SLinus Torvalds return error; 38181da177e4SLinus Torvalds 38191da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3820a74574aaSStephen Smalley if (!error) 3821f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38221da177e4SLinus Torvalds return error; 38231da177e4SLinus Torvalds } 38244d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38251da177e4SLinus Torvalds 38262e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38272e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38281da177e4SLinus Torvalds { 38292ad94ae6SAl Viro int error; 383091a27b2aSJeff Layton struct filename *from; 38316902d925SDave Hansen struct dentry *dentry; 3832dae6ad8fSAl Viro struct path path; 3833f46d3567SJeff Layton unsigned int lookup_flags = 0; 38341da177e4SLinus Torvalds 38351da177e4SLinus Torvalds from = getname(oldname); 38361da177e4SLinus Torvalds if (IS_ERR(from)) 38371da177e4SLinus Torvalds return PTR_ERR(from); 3838f46d3567SJeff Layton retry: 3839f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 38401da177e4SLinus Torvalds error = PTR_ERR(dentry); 38416902d925SDave Hansen if (IS_ERR(dentry)) 3842dae6ad8fSAl Viro goto out_putname; 38436902d925SDave Hansen 384491a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3845a8104a9fSAl Viro if (!error) 384691a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3847921a1650SAl Viro done_path_create(&path, dentry); 3848f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3849f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3850f46d3567SJeff Layton goto retry; 3851f46d3567SJeff Layton } 38526902d925SDave Hansen out_putname: 38531da177e4SLinus Torvalds putname(from); 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds } 38561da177e4SLinus Torvalds 38573480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 38585590ff0dSUlrich Drepper { 38595590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 38605590ff0dSUlrich Drepper } 38615590ff0dSUlrich Drepper 3862146a8595SJ. Bruce Fields /** 3863146a8595SJ. Bruce Fields * vfs_link - create a new link 3864146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3865146a8595SJ. Bruce Fields * @dir: new parent 3866146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3867146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3868146a8595SJ. Bruce Fields * 3869146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3870146a8595SJ. Bruce Fields * 3871146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3872146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3873146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3874146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3875146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3876146a8595SJ. Bruce Fields * 3877146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3878146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3879146a8595SJ. Bruce Fields * to be NFS exported. 3880146a8595SJ. Bruce Fields */ 3881146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 38821da177e4SLinus Torvalds { 38831da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 38848de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 38851da177e4SLinus Torvalds int error; 38861da177e4SLinus Torvalds 38871da177e4SLinus Torvalds if (!inode) 38881da177e4SLinus Torvalds return -ENOENT; 38891da177e4SLinus Torvalds 3890a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 38911da177e4SLinus Torvalds if (error) 38921da177e4SLinus Torvalds return error; 38931da177e4SLinus Torvalds 38941da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 38951da177e4SLinus Torvalds return -EXDEV; 38961da177e4SLinus Torvalds 38971da177e4SLinus Torvalds /* 38981da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 38991da177e4SLinus Torvalds */ 39001da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39011da177e4SLinus Torvalds return -EPERM; 3902acfa4380SAl Viro if (!dir->i_op->link) 39031da177e4SLinus Torvalds return -EPERM; 39047e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39051da177e4SLinus Torvalds return -EPERM; 39061da177e4SLinus Torvalds 39071da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39081da177e4SLinus Torvalds if (error) 39091da177e4SLinus Torvalds return error; 39101da177e4SLinus Torvalds 39117e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3912aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3913f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3914aae8a97dSAneesh Kumar K.V error = -ENOENT; 39158de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39168de52778SAl Viro error = -EMLINK; 3917146a8595SJ. Bruce Fields else { 3918146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3919146a8595SJ. Bruce Fields if (!error) 39201da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3921146a8595SJ. Bruce Fields } 3922f4e0c30cSAl Viro 3923f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3924f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3925f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3926f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3927f4e0c30cSAl Viro } 39287e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3929e31e14ecSStephen Smalley if (!error) 39307e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39311da177e4SLinus Torvalds return error; 39321da177e4SLinus Torvalds } 39334d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39341da177e4SLinus Torvalds 39351da177e4SLinus Torvalds /* 39361da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39371da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 39381da177e4SLinus Torvalds * newname. --KAB 39391da177e4SLinus Torvalds * 39401da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 39411da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 39421da177e4SLinus Torvalds * and other special files. --ADM 39431da177e4SLinus Torvalds */ 39442e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 39452e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 39461da177e4SLinus Torvalds { 39471da177e4SLinus Torvalds struct dentry *new_dentry; 3948dae6ad8fSAl Viro struct path old_path, new_path; 3949146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 395011a7b371SAneesh Kumar K.V int how = 0; 39511da177e4SLinus Torvalds int error; 39521da177e4SLinus Torvalds 395311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3954c04030e1SUlrich Drepper return -EINVAL; 395511a7b371SAneesh Kumar K.V /* 3956f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3957f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3958f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 395911a7b371SAneesh Kumar K.V */ 3960f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3961f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3962f0cc6ffbSLinus Torvalds return -ENOENT; 396311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3964f0cc6ffbSLinus Torvalds } 3965c04030e1SUlrich Drepper 396611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 396711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 3968442e31caSJeff Layton retry: 396911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 39701da177e4SLinus Torvalds if (error) 39712ad94ae6SAl Viro return error; 39722ad94ae6SAl Viro 3973442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 3974442e31caSJeff Layton (how & LOOKUP_REVAL)); 39751da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 39766902d925SDave Hansen if (IS_ERR(new_dentry)) 3977dae6ad8fSAl Viro goto out; 3978dae6ad8fSAl Viro 3979dae6ad8fSAl Viro error = -EXDEV; 3980dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3981dae6ad8fSAl Viro goto out_dput; 3982800179c9SKees Cook error = may_linkat(&old_path); 3983800179c9SKees Cook if (unlikely(error)) 3984800179c9SKees Cook goto out_dput; 3985dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3986be6d3e56SKentaro Takeda if (error) 3987a8104a9fSAl Viro goto out_dput; 3988146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 398975c3f29dSDave Hansen out_dput: 3990921a1650SAl Viro done_path_create(&new_path, new_dentry); 3991146a8595SJ. Bruce Fields if (delegated_inode) { 3992146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3993d22e6338SOleg Drokin if (!error) { 3994d22e6338SOleg Drokin path_put(&old_path); 3995146a8595SJ. Bruce Fields goto retry; 3996146a8595SJ. Bruce Fields } 3997d22e6338SOleg Drokin } 3998442e31caSJeff Layton if (retry_estale(error, how)) { 3999d22e6338SOleg Drokin path_put(&old_path); 4000442e31caSJeff Layton how |= LOOKUP_REVAL; 4001442e31caSJeff Layton goto retry; 4002442e31caSJeff Layton } 40031da177e4SLinus Torvalds out: 40042d8f3038SAl Viro path_put(&old_path); 40051da177e4SLinus Torvalds 40061da177e4SLinus Torvalds return error; 40071da177e4SLinus Torvalds } 40081da177e4SLinus Torvalds 40093480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40105590ff0dSUlrich Drepper { 4011c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40125590ff0dSUlrich Drepper } 40135590ff0dSUlrich Drepper 4014bc27027aSMiklos Szeredi /** 4015bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4016bc27027aSMiklos Szeredi * @old_dir: parent of source 4017bc27027aSMiklos Szeredi * @old_dentry: source 4018bc27027aSMiklos Szeredi * @new_dir: parent of destination 4019bc27027aSMiklos Szeredi * @new_dentry: destination 4020bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4021520c8b16SMiklos Szeredi * @flags: rename flags 4022bc27027aSMiklos Szeredi * 4023bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4024bc27027aSMiklos Szeredi * 4025bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4026bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4027bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4028bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4029bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4030bc27027aSMiklos Szeredi * so. 4031bc27027aSMiklos Szeredi * 4032bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4033bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4034bc27027aSMiklos Szeredi * to be NFS exported. 4035bc27027aSMiklos Szeredi * 40361da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40371da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 40381da177e4SLinus Torvalds * Problems: 4039d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 40401da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 40411da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4042a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 40431da177e4SLinus Torvalds * story. 40446cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 40456cedba89SJ. Bruce Fields * and source (if it is not a directory). 40461b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 40471da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 40481da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4049a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 40501da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 40511da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 40521da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4053a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 40541da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 40551da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 40561da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4057e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 40581b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 40591da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4060c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 40611da177e4SLinus Torvalds * locking]. 40621da177e4SLinus Torvalds */ 40631da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40648e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4065520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 40661da177e4SLinus Torvalds { 40671da177e4SLinus Torvalds int error; 4068bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 406959b0df21SEric Paris const unsigned char *old_name; 4070bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4071bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4072da1ce067SMiklos Szeredi bool new_is_dir = false; 4073da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 40741da177e4SLinus Torvalds 4075bc27027aSMiklos Szeredi if (source == target) 40761da177e4SLinus Torvalds return 0; 40771da177e4SLinus Torvalds 40781da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 40791da177e4SLinus Torvalds if (error) 40801da177e4SLinus Torvalds return error; 40811da177e4SLinus Torvalds 4082da1ce067SMiklos Szeredi if (!target) { 4083a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4084da1ce067SMiklos Szeredi } else { 4085da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4086da1ce067SMiklos Szeredi 4087da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 40881da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4089da1ce067SMiklos Szeredi else 4090da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4091da1ce067SMiklos Szeredi } 40921da177e4SLinus Torvalds if (error) 40931da177e4SLinus Torvalds return error; 40941da177e4SLinus Torvalds 40957177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 40961da177e4SLinus Torvalds return -EPERM; 40971da177e4SLinus Torvalds 4098520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4099520c8b16SMiklos Szeredi return -EINVAL; 4100520c8b16SMiklos Szeredi 4101bc27027aSMiklos Szeredi /* 4102bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4103bc27027aSMiklos Szeredi * we'll need to flip '..'. 4104bc27027aSMiklos Szeredi */ 4105da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4106da1ce067SMiklos Szeredi if (is_dir) { 4107bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4108bc27027aSMiklos Szeredi if (error) 4109bc27027aSMiklos Szeredi return error; 4110bc27027aSMiklos Szeredi } 4111da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4112da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4113da1ce067SMiklos Szeredi if (error) 4114da1ce067SMiklos Szeredi return error; 4115da1ce067SMiklos Szeredi } 4116da1ce067SMiklos Szeredi } 41170eeca283SRobert Love 41180b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41190b3974ebSMiklos Szeredi flags); 4120bc27027aSMiklos Szeredi if (error) 4121bc27027aSMiklos Szeredi return error; 4122bc27027aSMiklos Szeredi 4123bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4124bc27027aSMiklos Szeredi dget(new_dentry); 4125da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4126bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4127bc27027aSMiklos Szeredi else if (target) 4128bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4129bc27027aSMiklos Szeredi 4130bc27027aSMiklos Szeredi error = -EBUSY; 41317af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 41327af1364fSEric W. Biederman goto out; 4133bc27027aSMiklos Szeredi if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 4134bc27027aSMiklos Szeredi goto out; 4135bc27027aSMiklos Szeredi 4136da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4137bc27027aSMiklos Szeredi error = -EMLINK; 4138da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4139bc27027aSMiklos Szeredi goto out; 4140da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4141da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4142da1ce067SMiklos Szeredi goto out; 4143da1ce067SMiklos Szeredi } 4144da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4145bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4146da1ce067SMiklos Szeredi if (!is_dir) { 4147bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4148bc27027aSMiklos Szeredi if (error) 4149bc27027aSMiklos Szeredi goto out; 4150da1ce067SMiklos Szeredi } 4151da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4152bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4153bc27027aSMiklos Szeredi if (error) 4154bc27027aSMiklos Szeredi goto out; 4155bc27027aSMiklos Szeredi } 41567177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4157520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4158520c8b16SMiklos Szeredi new_dir, new_dentry); 4159520c8b16SMiklos Szeredi } else { 41607177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4161520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4162520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4163520c8b16SMiklos Szeredi } 4164bc27027aSMiklos Szeredi if (error) 4165bc27027aSMiklos Szeredi goto out; 4166bc27027aSMiklos Szeredi 4167da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 41681da177e4SLinus Torvalds if (is_dir) 4169bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4170bc27027aSMiklos Szeredi dont_mount(new_dentry); 4171bc27027aSMiklos Szeredi } 4172da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4173da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4174bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4175da1ce067SMiklos Szeredi else 4176da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4177da1ce067SMiklos Szeredi } 4178bc27027aSMiklos Szeredi out: 4179da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4180bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4181bc27027aSMiklos Szeredi else if (target) 4182bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4183bc27027aSMiklos Szeredi dput(new_dentry); 4184da1ce067SMiklos Szeredi if (!error) { 4185123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4186da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4187da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4188da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4189da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4190da1ce067SMiklos Szeredi } 4191da1ce067SMiklos Szeredi } 41920eeca283SRobert Love fsnotify_oldname_free(old_name); 41930eeca283SRobert Love 41941da177e4SLinus Torvalds return error; 41951da177e4SLinus Torvalds } 41964d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 41971da177e4SLinus Torvalds 4198520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4199520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42001da177e4SLinus Torvalds { 42011da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 42021da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42031da177e4SLinus Torvalds struct dentry *trap; 42041da177e4SLinus Torvalds struct nameidata oldnd, newnd; 42058e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 420691a27b2aSJeff Layton struct filename *from; 420791a27b2aSJeff Layton struct filename *to; 4208c6a94284SJeff Layton unsigned int lookup_flags = 0; 4209c6a94284SJeff Layton bool should_retry = false; 42102ad94ae6SAl Viro int error; 4211520c8b16SMiklos Szeredi 4212da1ce067SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 4213da1ce067SMiklos Szeredi return -EINVAL; 4214da1ce067SMiklos Szeredi 4215da1ce067SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && (flags & RENAME_EXCHANGE)) 4216520c8b16SMiklos Szeredi return -EINVAL; 4217520c8b16SMiklos Szeredi 4218c6a94284SJeff Layton retry: 4219c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 422091a27b2aSJeff Layton if (IS_ERR(from)) { 422191a27b2aSJeff Layton error = PTR_ERR(from); 42221da177e4SLinus Torvalds goto exit; 422391a27b2aSJeff Layton } 42241da177e4SLinus Torvalds 4225c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 422691a27b2aSJeff Layton if (IS_ERR(to)) { 422791a27b2aSJeff Layton error = PTR_ERR(to); 42281da177e4SLinus Torvalds goto exit1; 422991a27b2aSJeff Layton } 42301da177e4SLinus Torvalds 42311da177e4SLinus Torvalds error = -EXDEV; 42324ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 42331da177e4SLinus Torvalds goto exit2; 42341da177e4SLinus Torvalds 42354ac91378SJan Blunck old_dir = oldnd.path.dentry; 42361da177e4SLinus Torvalds error = -EBUSY; 42371da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 42381da177e4SLinus Torvalds goto exit2; 42391da177e4SLinus Torvalds 42404ac91378SJan Blunck new_dir = newnd.path.dentry; 42410a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 42420a7c3937SMiklos Szeredi error = -EEXIST; 42431da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 42441da177e4SLinus Torvalds goto exit2; 42451da177e4SLinus Torvalds 4246c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4247c30dabfeSJan Kara if (error) 4248c30dabfeSJan Kara goto exit2; 4249c30dabfeSJan Kara 42500612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 42510612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 4252da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42534e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 42540612d9fbSOGAWA Hirofumi 42558e6d782cSJ. Bruce Fields retry_deleg: 42561da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 42571da177e4SLinus Torvalds 425849705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 42591da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 42601da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 42611da177e4SLinus Torvalds goto exit3; 42621da177e4SLinus Torvalds /* source must exist */ 42631da177e4SLinus Torvalds error = -ENOENT; 4264b18825a7SDavid Howells if (d_is_negative(old_dentry)) 42651da177e4SLinus Torvalds goto exit4; 426649705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 42671da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42681da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 42691da177e4SLinus Torvalds goto exit4; 42700a7c3937SMiklos Szeredi error = -EEXIST; 42710a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 42720a7c3937SMiklos Szeredi goto exit5; 4273da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4274da1ce067SMiklos Szeredi error = -ENOENT; 4275da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4276da1ce067SMiklos Szeredi goto exit5; 4277da1ce067SMiklos Szeredi 4278da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4279da1ce067SMiklos Szeredi error = -ENOTDIR; 4280da1ce067SMiklos Szeredi if (newnd.last.name[newnd.last.len]) 4281da1ce067SMiklos Szeredi goto exit5; 4282da1ce067SMiklos Szeredi } 4283da1ce067SMiklos Szeredi } 42840a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 42850a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 42860a7c3937SMiklos Szeredi error = -ENOTDIR; 42870a7c3937SMiklos Szeredi if (oldnd.last.name[oldnd.last.len]) 42880a7c3937SMiklos Szeredi goto exit5; 4289da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) 42900a7c3937SMiklos Szeredi goto exit5; 42910a7c3937SMiklos Szeredi } 42920a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 42930a7c3937SMiklos Szeredi error = -EINVAL; 42940a7c3937SMiklos Szeredi if (old_dentry == trap) 42950a7c3937SMiklos Szeredi goto exit5; 42961da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4297da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42981da177e4SLinus Torvalds error = -ENOTEMPTY; 42991da177e4SLinus Torvalds if (new_dentry == trap) 43001da177e4SLinus Torvalds goto exit5; 43011da177e4SLinus Torvalds 4302be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 43030b3974ebSMiklos Szeredi &newnd.path, new_dentry, flags); 4304be6d3e56SKentaro Takeda if (error) 4305c30dabfeSJan Kara goto exit5; 43061da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 43078e6d782cSJ. Bruce Fields new_dir->d_inode, new_dentry, 4308520c8b16SMiklos Szeredi &delegated_inode, flags); 43091da177e4SLinus Torvalds exit5: 43101da177e4SLinus Torvalds dput(new_dentry); 43111da177e4SLinus Torvalds exit4: 43121da177e4SLinus Torvalds dput(old_dentry); 43131da177e4SLinus Torvalds exit3: 43141da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 43158e6d782cSJ. Bruce Fields if (delegated_inode) { 43168e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43178e6d782cSJ. Bruce Fields if (!error) 43188e6d782cSJ. Bruce Fields goto retry_deleg; 43198e6d782cSJ. Bruce Fields } 4320c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 43211da177e4SLinus Torvalds exit2: 4322c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4323c6a94284SJeff Layton should_retry = true; 43241d957f9bSJan Blunck path_put(&newnd.path); 43252ad94ae6SAl Viro putname(to); 43261da177e4SLinus Torvalds exit1: 43271d957f9bSJan Blunck path_put(&oldnd.path); 43281da177e4SLinus Torvalds putname(from); 4329c6a94284SJeff Layton if (should_retry) { 4330c6a94284SJeff Layton should_retry = false; 4331c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4332c6a94284SJeff Layton goto retry; 4333c6a94284SJeff Layton } 43342ad94ae6SAl Viro exit: 43351da177e4SLinus Torvalds return error; 43361da177e4SLinus Torvalds } 43371da177e4SLinus Torvalds 4338520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4339520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4340520c8b16SMiklos Szeredi { 4341520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4342520c8b16SMiklos Szeredi } 4343520c8b16SMiklos Szeredi 4344a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 43455590ff0dSUlrich Drepper { 4346520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43475590ff0dSUlrich Drepper } 43485590ff0dSUlrich Drepper 43495d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 43501da177e4SLinus Torvalds { 43515d826c84SAl Viro int len = PTR_ERR(link); 43521da177e4SLinus Torvalds if (IS_ERR(link)) 43531da177e4SLinus Torvalds goto out; 43541da177e4SLinus Torvalds 43551da177e4SLinus Torvalds len = strlen(link); 43561da177e4SLinus Torvalds if (len > (unsigned) buflen) 43571da177e4SLinus Torvalds len = buflen; 43581da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 43591da177e4SLinus Torvalds len = -EFAULT; 43601da177e4SLinus Torvalds out: 43611da177e4SLinus Torvalds return len; 43621da177e4SLinus Torvalds } 43635d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 43641da177e4SLinus Torvalds 43651da177e4SLinus Torvalds /* 43661da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 43671da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 43681da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 43691da177e4SLinus Torvalds */ 43701da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 43711da177e4SLinus Torvalds { 43721da177e4SLinus Torvalds struct nameidata nd; 4373cc314eefSLinus Torvalds void *cookie; 4374694a1764SMarcin Slusarz int res; 4375cc314eefSLinus Torvalds 43761da177e4SLinus Torvalds nd.depth = 0; 4377cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4378694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4379694a1764SMarcin Slusarz return PTR_ERR(cookie); 4380694a1764SMarcin Slusarz 43815d826c84SAl Viro res = readlink_copy(buffer, buflen, nd_get_link(&nd)); 43821da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4383cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4384694a1764SMarcin Slusarz return res; 43851da177e4SLinus Torvalds } 43864d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 43871da177e4SLinus Torvalds 43881da177e4SLinus Torvalds /* get the link contents into pagecache */ 43891da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 43901da177e4SLinus Torvalds { 4391ebd09abbSDuane Griffin char *kaddr; 43921da177e4SLinus Torvalds struct page *page; 43931da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4394090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 43951da177e4SLinus Torvalds if (IS_ERR(page)) 43966fe6900eSNick Piggin return (char*)page; 43971da177e4SLinus Torvalds *ppage = page; 4398ebd09abbSDuane Griffin kaddr = kmap(page); 4399ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4400ebd09abbSDuane Griffin return kaddr; 44011da177e4SLinus Torvalds } 44021da177e4SLinus Torvalds 44031da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44041da177e4SLinus Torvalds { 44051da177e4SLinus Torvalds struct page *page = NULL; 44065d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44071da177e4SLinus Torvalds if (page) { 44081da177e4SLinus Torvalds kunmap(page); 44091da177e4SLinus Torvalds page_cache_release(page); 44101da177e4SLinus Torvalds } 44111da177e4SLinus Torvalds return res; 44121da177e4SLinus Torvalds } 44134d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44141da177e4SLinus Torvalds 4415cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 44161da177e4SLinus Torvalds { 4417cc314eefSLinus Torvalds struct page *page = NULL; 44181da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4419cc314eefSLinus Torvalds return page; 44201da177e4SLinus Torvalds } 44214d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 44221da177e4SLinus Torvalds 4423cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 44241da177e4SLinus Torvalds { 4425cc314eefSLinus Torvalds struct page *page = cookie; 4426cc314eefSLinus Torvalds 4427cc314eefSLinus Torvalds if (page) { 44281da177e4SLinus Torvalds kunmap(page); 44291da177e4SLinus Torvalds page_cache_release(page); 44301da177e4SLinus Torvalds } 44311da177e4SLinus Torvalds } 44324d359507SAl Viro EXPORT_SYMBOL(page_put_link); 44331da177e4SLinus Torvalds 443454566b2cSNick Piggin /* 443554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 443654566b2cSNick Piggin */ 443754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 44381da177e4SLinus Torvalds { 44391da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 44400adb25d2SKirill Korotaev struct page *page; 4441afddba49SNick Piggin void *fsdata; 4442beb497abSDmitriy Monakhov int err; 44431da177e4SLinus Torvalds char *kaddr; 444454566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 444554566b2cSNick Piggin if (nofs) 444654566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 44471da177e4SLinus Torvalds 44487e53cac4SNeilBrown retry: 4449afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 445054566b2cSNick Piggin flags, &page, &fsdata); 44511da177e4SLinus Torvalds if (err) 4452afddba49SNick Piggin goto fail; 4453afddba49SNick Piggin 4454e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 44551da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4456e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4457afddba49SNick Piggin 4458afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4459afddba49SNick Piggin page, fsdata); 44601da177e4SLinus Torvalds if (err < 0) 44611da177e4SLinus Torvalds goto fail; 4462afddba49SNick Piggin if (err < len-1) 4463afddba49SNick Piggin goto retry; 4464afddba49SNick Piggin 44651da177e4SLinus Torvalds mark_inode_dirty(inode); 44661da177e4SLinus Torvalds return 0; 44671da177e4SLinus Torvalds fail: 44681da177e4SLinus Torvalds return err; 44691da177e4SLinus Torvalds } 44704d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 44711da177e4SLinus Torvalds 44720adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 44730adb25d2SKirill Korotaev { 44740adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 447554566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 44760adb25d2SKirill Korotaev } 44774d359507SAl Viro EXPORT_SYMBOL(page_symlink); 44780adb25d2SKirill Korotaev 447992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 44801da177e4SLinus Torvalds .readlink = generic_readlink, 44811da177e4SLinus Torvalds .follow_link = page_follow_link_light, 44821da177e4SLinus Torvalds .put_link = page_put_link, 44831da177e4SLinus Torvalds }; 44841da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4485