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> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/pagemap.h> 230eeca283SRobert Love #include <linux/fsnotify.h> 241da177e4SLinus Torvalds #include <linux/personality.h> 251da177e4SLinus Torvalds #include <linux/security.h> 266146f0d5SMimi Zohar #include <linux/ima.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 345ad4e53bSAl Viro #include <linux/fs_struct.h> 35e77819e5SLinus Torvalds #include <linux/posix_acl.h> 361da177e4SLinus Torvalds #include <asm/uaccess.h> 371da177e4SLinus Torvalds 38e81e3f4dSEric Paris #include "internal.h" 39c7105365SAl Viro #include "mount.h" 40e81e3f4dSEric Paris 411da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 421da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 431da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 441da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 451da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 461da177e4SLinus Torvalds * 471da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 481da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 491da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 501da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 511da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 521da177e4SLinus Torvalds * the special cases of the former code. 531da177e4SLinus Torvalds * 541da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 551da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 561da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 591da177e4SLinus Torvalds * resolution to correspond with current state of the code. 601da177e4SLinus Torvalds * 611da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 621da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 631da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 641da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 651da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 661da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 671da177e4SLinus Torvalds */ 681da177e4SLinus Torvalds 691da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 701da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 711da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 721da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 731da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 741da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7525985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 761da177e4SLinus Torvalds * 771da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 781da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 791da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 801da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 811da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 821da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 831da177e4SLinus Torvalds * and in the old Linux semantics. 841da177e4SLinus Torvalds */ 851da177e4SLinus Torvalds 861da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 871da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 881da177e4SLinus Torvalds * 891da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 901da177e4SLinus Torvalds */ 911da177e4SLinus Torvalds 921da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 931da177e4SLinus Torvalds * inside the path - always follow. 941da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 951da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 961da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 971da177e4SLinus Torvalds * otherwise - don't follow. 981da177e4SLinus Torvalds * (applied in that order). 991da177e4SLinus Torvalds * 1001da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1011da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1021da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1031da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1041da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1051da177e4SLinus Torvalds */ 1061da177e4SLinus Torvalds /* 1071da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 108a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1091da177e4SLinus Torvalds * any extra contention... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds 1121da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1131da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1141da177e4SLinus Torvalds * kernel data space before using them.. 1151da177e4SLinus Torvalds * 1161da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1171da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1181da177e4SLinus Torvalds */ 119858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds int retval; 1221da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1231da177e4SLinus Torvalds 1241da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1251da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1261da177e4SLinus Torvalds return -EFAULT; 1271da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1281da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1321da177e4SLinus Torvalds if (retval > 0) { 1331da177e4SLinus Torvalds if (retval < len) 1341da177e4SLinus Torvalds return 0; 1351da177e4SLinus Torvalds return -ENAMETOOLONG; 1361da177e4SLinus Torvalds } else if (!retval) 1371da177e4SLinus Torvalds retval = -ENOENT; 1381da177e4SLinus Torvalds return retval; 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411fa1e7f6SAndy Whitcroft static char *getname_flags(const char __user *filename, int flags, int *empty) 1421da177e4SLinus Torvalds { 1434043cde8SEric Paris char *result = __getname(); 1444043cde8SEric Paris int retval; 1451da177e4SLinus Torvalds 1464043cde8SEric Paris if (!result) 1474043cde8SEric Paris return ERR_PTR(-ENOMEM); 1481da177e4SLinus Torvalds 1494043cde8SEric Paris retval = do_getname(filename, result); 1501da177e4SLinus Torvalds if (retval < 0) { 1511fa1e7f6SAndy Whitcroft if (retval == -ENOENT && empty) 1521fa1e7f6SAndy Whitcroft *empty = 1; 153f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1544043cde8SEric Paris __putname(result); 1554043cde8SEric Paris return ERR_PTR(retval); 1561da177e4SLinus Torvalds } 157f52e0c11SAl Viro } 1581da177e4SLinus Torvalds audit_getname(result); 1591da177e4SLinus Torvalds return result; 1601da177e4SLinus Torvalds } 1611da177e4SLinus Torvalds 162f52e0c11SAl Viro char *getname(const char __user * filename) 163f52e0c11SAl Viro { 164f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 165f52e0c11SAl Viro } 166f52e0c11SAl Viro 1671da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1681da177e4SLinus Torvalds void putname(const char *name) 1691da177e4SLinus Torvalds { 1705ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1711da177e4SLinus Torvalds audit_putname(name); 1721da177e4SLinus Torvalds else 1731da177e4SLinus Torvalds __putname(name); 1741da177e4SLinus Torvalds } 1751da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1761da177e4SLinus Torvalds #endif 1771da177e4SLinus Torvalds 178e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 179e77819e5SLinus Torvalds { 18084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 181e77819e5SLinus Torvalds struct posix_acl *acl; 182e77819e5SLinus Torvalds 183e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 1843567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 1853567866bSAl Viro if (!acl) 186e77819e5SLinus Torvalds return -EAGAIN; 1873567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 1883567866bSAl Viro if (acl == ACL_NOT_CACHED) 189e77819e5SLinus Torvalds return -ECHILD; 190206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 191e77819e5SLinus Torvalds } 192e77819e5SLinus Torvalds 193e77819e5SLinus Torvalds acl = get_cached_acl(inode, ACL_TYPE_ACCESS); 194e77819e5SLinus Torvalds 195e77819e5SLinus Torvalds /* 1964e34e719SChristoph Hellwig * A filesystem can force a ACL callback by just never filling the 1974e34e719SChristoph Hellwig * ACL cache. But normally you'd fill the cache either at inode 1984e34e719SChristoph Hellwig * instantiation time, or on the first ->get_acl call. 199e77819e5SLinus Torvalds * 2004e34e719SChristoph Hellwig * If the filesystem doesn't have a get_acl() function at all, we'll 2014e34e719SChristoph Hellwig * just create the negative cache entry. 202e77819e5SLinus Torvalds */ 203e77819e5SLinus Torvalds if (acl == ACL_NOT_CACHED) { 2044e34e719SChristoph Hellwig if (inode->i_op->get_acl) { 2054e34e719SChristoph Hellwig acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); 2064e34e719SChristoph Hellwig if (IS_ERR(acl)) 2074e34e719SChristoph Hellwig return PTR_ERR(acl); 2084e34e719SChristoph Hellwig } else { 209e77819e5SLinus Torvalds set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); 210e77819e5SLinus Torvalds return -EAGAIN; 211e77819e5SLinus Torvalds } 2124e34e719SChristoph Hellwig } 213e77819e5SLinus Torvalds 214e77819e5SLinus Torvalds if (acl) { 215e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 216e77819e5SLinus Torvalds posix_acl_release(acl); 217e77819e5SLinus Torvalds return error; 218e77819e5SLinus Torvalds } 21984635d68SLinus Torvalds #endif 220e77819e5SLinus Torvalds 221e77819e5SLinus Torvalds return -EAGAIN; 222e77819e5SLinus Torvalds } 223e77819e5SLinus Torvalds 2245909ccaaSLinus Torvalds /* 225948409c7SAndreas Gruenbacher * This does the basic permission checking 2265909ccaaSLinus Torvalds */ 2277e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2285909ccaaSLinus Torvalds { 22926cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2305909ccaaSLinus Torvalds 231e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 232e795b717SSerge E. Hallyn goto other_perms; 233e795b717SSerge E. Hallyn 23414067ff5SLinus Torvalds if (likely(current_fsuid() == inode->i_uid)) 2355909ccaaSLinus Torvalds mode >>= 6; 2365909ccaaSLinus Torvalds else { 237e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2387e40145eSAl Viro int error = check_acl(inode, mask); 2395909ccaaSLinus Torvalds if (error != -EAGAIN) 2405909ccaaSLinus Torvalds return error; 2415909ccaaSLinus Torvalds } 2425909ccaaSLinus Torvalds 2435909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2445909ccaaSLinus Torvalds mode >>= 3; 2455909ccaaSLinus Torvalds } 2465909ccaaSLinus Torvalds 247e795b717SSerge E. Hallyn other_perms: 2485909ccaaSLinus Torvalds /* 2495909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2505909ccaaSLinus Torvalds */ 2519c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2525909ccaaSLinus Torvalds return 0; 2535909ccaaSLinus Torvalds return -EACCES; 2545909ccaaSLinus Torvalds } 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds /** 2571da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2581da177e4SLinus Torvalds * @inode: inode to check access rights for 2598fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 2601da177e4SLinus Torvalds * 2611da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2621da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2631da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 264b74c79e9SNick Piggin * are used for other things. 265b74c79e9SNick Piggin * 266b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 267b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 268b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2691da177e4SLinus Torvalds */ 2702830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2711da177e4SLinus Torvalds { 2725909ccaaSLinus Torvalds int ret; 2731da177e4SLinus Torvalds 2741da177e4SLinus Torvalds /* 275948409c7SAndreas Gruenbacher * Do the basic permission checks. 2761da177e4SLinus Torvalds */ 2777e40145eSAl Viro ret = acl_permission_check(inode, mask); 2785909ccaaSLinus Torvalds if (ret != -EACCES) 2795909ccaaSLinus Torvalds return ret; 2801da177e4SLinus Torvalds 281d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 282d594e7ecSAl Viro /* DACs are overridable for directories */ 283d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 284d594e7ecSAl Viro return 0; 285d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 286d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 287d594e7ecSAl Viro return 0; 288d594e7ecSAl Viro return -EACCES; 289d594e7ecSAl Viro } 2901da177e4SLinus Torvalds /* 2911da177e4SLinus Torvalds * Read/write DACs are always overridable. 292d594e7ecSAl Viro * Executable DACs are overridable when there is 293d594e7ecSAl Viro * at least one exec bit set. 2941da177e4SLinus Torvalds */ 295d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 296e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 2971da177e4SLinus Torvalds return 0; 2981da177e4SLinus Torvalds 2991da177e4SLinus Torvalds /* 3001da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3011da177e4SLinus Torvalds */ 3027ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 303d594e7ecSAl Viro if (mask == MAY_READ) 304e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 3051da177e4SLinus Torvalds return 0; 3061da177e4SLinus Torvalds 3071da177e4SLinus Torvalds return -EACCES; 3081da177e4SLinus Torvalds } 3091da177e4SLinus Torvalds 3103ddcd056SLinus Torvalds /* 3113ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3123ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3133ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3143ddcd056SLinus Torvalds * permission function, use the fast case". 3153ddcd056SLinus Torvalds */ 3163ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3173ddcd056SLinus Torvalds { 3183ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3193ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3203ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3213ddcd056SLinus Torvalds 3223ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3233ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3243ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3253ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3263ddcd056SLinus Torvalds } 3273ddcd056SLinus Torvalds return generic_permission(inode, mask); 3283ddcd056SLinus Torvalds } 3293ddcd056SLinus Torvalds 330cb23beb5SChristoph Hellwig /** 331cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 332cb23beb5SChristoph Hellwig * @inode: inode to check permission on 3338fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 334cb23beb5SChristoph Hellwig * 335cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 336cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 337cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 338cb23beb5SChristoph Hellwig * are used for other things. 339948409c7SAndreas Gruenbacher * 340948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 341cb23beb5SChristoph Hellwig */ 342f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 3431da177e4SLinus Torvalds { 344e6305c43SAl Viro int retval; 3451da177e4SLinus Torvalds 3463ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 34722590e41SMiklos Szeredi umode_t mode = inode->i_mode; 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 3511da177e4SLinus Torvalds */ 3521da177e4SLinus Torvalds if (IS_RDONLY(inode) && 3531da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 3541da177e4SLinus Torvalds return -EROFS; 3551da177e4SLinus Torvalds 3561da177e4SLinus Torvalds /* 3571da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3581da177e4SLinus Torvalds */ 3591da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3601da177e4SLinus Torvalds return -EACCES; 3611da177e4SLinus Torvalds } 3621da177e4SLinus Torvalds 3633ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3641da177e4SLinus Torvalds if (retval) 3651da177e4SLinus Torvalds return retval; 3661da177e4SLinus Torvalds 36708ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 36808ce5f16SSerge E. Hallyn if (retval) 36908ce5f16SSerge E. Hallyn return retval; 37008ce5f16SSerge E. Hallyn 371d09ca739SEric Paris return security_inode_permission(inode, mask); 3721da177e4SLinus Torvalds } 3731da177e4SLinus Torvalds 374f4d6ff89SAl Viro /** 3755dd784d0SJan Blunck * path_get - get a reference to a path 3765dd784d0SJan Blunck * @path: path to get the reference to 3775dd784d0SJan Blunck * 3785dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3795dd784d0SJan Blunck */ 3805dd784d0SJan Blunck void path_get(struct path *path) 3815dd784d0SJan Blunck { 3825dd784d0SJan Blunck mntget(path->mnt); 3835dd784d0SJan Blunck dget(path->dentry); 3845dd784d0SJan Blunck } 3855dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3865dd784d0SJan Blunck 3875dd784d0SJan Blunck /** 3881d957f9bSJan Blunck * path_put - put a reference to a path 3891d957f9bSJan Blunck * @path: path to put the reference to 3901d957f9bSJan Blunck * 3911d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3921d957f9bSJan Blunck */ 3931d957f9bSJan Blunck void path_put(struct path *path) 3941da177e4SLinus Torvalds { 3951d957f9bSJan Blunck dput(path->dentry); 3961d957f9bSJan Blunck mntput(path->mnt); 3971da177e4SLinus Torvalds } 3981d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3991da177e4SLinus Torvalds 40019660af7SAl Viro /* 40131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 40219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 40319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 40419660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 40519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 40619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 40719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 40819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 40931e6b01fSNick Piggin */ 41031e6b01fSNick Piggin 41131e6b01fSNick Piggin /** 41219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 41319660af7SAl Viro * @nd: nameidata pathwalk data 41419660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 41539191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 41631e6b01fSNick Piggin * 41719660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 41819660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 41919660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 42031e6b01fSNick Piggin */ 42119660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 42231e6b01fSNick Piggin { 42331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 42431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4255b6ca027SAl Viro int want_root = 0; 42631e6b01fSNick Piggin 42731e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4285b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4295b6ca027SAl Viro want_root = 1; 43031e6b01fSNick Piggin spin_lock(&fs->lock); 43131e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 43231e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 43331e6b01fSNick Piggin goto err_root; 43431e6b01fSNick Piggin } 43531e6b01fSNick Piggin spin_lock(&parent->d_lock); 43619660af7SAl Viro if (!dentry) { 43719660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 43819660af7SAl Viro goto err_parent; 43919660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 44019660af7SAl Viro } else { 44194c0d4ecSAl Viro if (dentry->d_parent != parent) 44294c0d4ecSAl Viro goto err_parent; 44331e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 44431e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 44519660af7SAl Viro goto err_child; 44631e6b01fSNick Piggin /* 44719660af7SAl Viro * If the sequence check on the child dentry passed, then 44819660af7SAl Viro * the child has not been removed from its parent. This 44919660af7SAl Viro * means the parent dentry must be valid and able to take 45019660af7SAl Viro * a reference at this point. 45131e6b01fSNick Piggin */ 45231e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 45331e6b01fSNick Piggin BUG_ON(!parent->d_count); 45431e6b01fSNick Piggin parent->d_count++; 45531e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 45619660af7SAl Viro } 45731e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4585b6ca027SAl Viro if (want_root) { 45931e6b01fSNick Piggin path_get(&nd->root); 46031e6b01fSNick Piggin spin_unlock(&fs->lock); 46131e6b01fSNick Piggin } 46231e6b01fSNick Piggin mntget(nd->path.mnt); 46331e6b01fSNick Piggin 46431e6b01fSNick Piggin rcu_read_unlock(); 46531e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 46631e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 46731e6b01fSNick Piggin return 0; 46819660af7SAl Viro 46919660af7SAl Viro err_child: 47031e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 47119660af7SAl Viro err_parent: 47231e6b01fSNick Piggin spin_unlock(&parent->d_lock); 47331e6b01fSNick Piggin err_root: 4745b6ca027SAl Viro if (want_root) 47531e6b01fSNick Piggin spin_unlock(&fs->lock); 47631e6b01fSNick Piggin return -ECHILD; 47731e6b01fSNick Piggin } 47831e6b01fSNick Piggin 47931e6b01fSNick Piggin /** 480834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 481834f2a4aSTrond Myklebust * @nd: pointer to nameidata 482834f2a4aSTrond Myklebust */ 483834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 484834f2a4aSTrond Myklebust { 4852dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4862dab5974SLinus Torvalds 4872dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4882dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4892dab5974SLinus Torvalds put_filp(file); 490834f2a4aSTrond Myklebust else 4912dab5974SLinus Torvalds fput(file); 4922dab5974SLinus Torvalds } 493834f2a4aSTrond Myklebust } 494834f2a4aSTrond Myklebust 495f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 49634286d66SNick Piggin { 497f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 49834286d66SNick Piggin } 49934286d66SNick Piggin 5009f1fafeeSAl Viro /** 5019f1fafeeSAl Viro * complete_walk - successful completion of path walk 5029f1fafeeSAl Viro * @nd: pointer nameidata 50339159de2SJeff Layton * 5049f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5059f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5069f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5079f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5089f1fafeeSAl Viro * need to drop nd->path. 50939159de2SJeff Layton */ 5109f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 51139159de2SJeff Layton { 51216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 51339159de2SJeff Layton int status; 51439159de2SJeff Layton 5159f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5169f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5179f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5189f1fafeeSAl Viro nd->root.mnt = NULL; 5199f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5209f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5219f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5229f1fafeeSAl Viro rcu_read_unlock(); 5239f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5249f1fafeeSAl Viro return -ECHILD; 5259f1fafeeSAl Viro } 5269f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5279f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5289f1fafeeSAl Viro mntget(nd->path.mnt); 5299f1fafeeSAl Viro rcu_read_unlock(); 5309f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5319f1fafeeSAl Viro } 5329f1fafeeSAl Viro 53316c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 53439159de2SJeff Layton return 0; 53539159de2SJeff Layton 53616c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 53716c2cd71SAl Viro return 0; 53816c2cd71SAl Viro 53916c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 54016c2cd71SAl Viro return 0; 54116c2cd71SAl Viro 54216c2cd71SAl Viro /* Note: we do not d_invalidate() */ 54334286d66SNick Piggin status = d_revalidate(dentry, nd); 54439159de2SJeff Layton if (status > 0) 54539159de2SJeff Layton return 0; 54639159de2SJeff Layton 54716c2cd71SAl Viro if (!status) 54839159de2SJeff Layton status = -ESTALE; 54916c2cd71SAl Viro 5509f1fafeeSAl Viro path_put(&nd->path); 55139159de2SJeff Layton return status; 55239159de2SJeff Layton } 55339159de2SJeff Layton 5542a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5552a737871SAl Viro { 556f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 557f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5582a737871SAl Viro } 5592a737871SAl Viro 5606de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5616de88d72SAl Viro 56231e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 56331e6b01fSNick Piggin { 56431e6b01fSNick Piggin if (!nd->root.mnt) { 56531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 566c28cc364SNick Piggin unsigned seq; 567c28cc364SNick Piggin 568c28cc364SNick Piggin do { 569c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 57031e6b01fSNick Piggin nd->root = fs->root; 571c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 572c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 57331e6b01fSNick Piggin } 57431e6b01fSNick Piggin } 57531e6b01fSNick Piggin 576f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5771da177e4SLinus Torvalds { 57831e6b01fSNick Piggin int ret; 57931e6b01fSNick Piggin 5801da177e4SLinus Torvalds if (IS_ERR(link)) 5811da177e4SLinus Torvalds goto fail; 5821da177e4SLinus Torvalds 5831da177e4SLinus Torvalds if (*link == '/') { 5842a737871SAl Viro set_root(nd); 5851d957f9bSJan Blunck path_put(&nd->path); 5862a737871SAl Viro nd->path = nd->root; 5872a737871SAl Viro path_get(&nd->root); 58816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 5891da177e4SLinus Torvalds } 59031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 591b4091d5fSChristoph Hellwig 59231e6b01fSNick Piggin ret = link_path_walk(link, nd); 59331e6b01fSNick Piggin return ret; 5941da177e4SLinus Torvalds fail: 5951d957f9bSJan Blunck path_put(&nd->path); 5961da177e4SLinus Torvalds return PTR_ERR(link); 5971da177e4SLinus Torvalds } 5981da177e4SLinus Torvalds 5991d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 600051d3812SIan Kent { 601051d3812SIan Kent dput(path->dentry); 6024ac91378SJan Blunck if (path->mnt != nd->path.mnt) 603051d3812SIan Kent mntput(path->mnt); 604051d3812SIan Kent } 605051d3812SIan Kent 6067b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6077b9337aaSNick Piggin struct nameidata *nd) 608051d3812SIan Kent { 60931e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6104ac91378SJan Blunck dput(nd->path.dentry); 61131e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6124ac91378SJan Blunck mntput(nd->path.mnt); 6139a229683SHuang Shijie } 61431e6b01fSNick Piggin nd->path.mnt = path->mnt; 6154ac91378SJan Blunck nd->path.dentry = path->dentry; 616051d3812SIan Kent } 617051d3812SIan Kent 618574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 619574197e0SAl Viro { 620574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 621574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 622574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 623574197e0SAl Viro path_put(link); 624574197e0SAl Viro } 625574197e0SAl Viro 626def4af30SAl Viro static __always_inline int 627574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6281da177e4SLinus Torvalds { 6291da177e4SLinus Torvalds int error; 6307b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6311da177e4SLinus Torvalds 632844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 633844a3917SAl Viro 6340e794589SAl Viro if (link->mnt == nd->path.mnt) 6350e794589SAl Viro mntget(link->mnt); 6360e794589SAl Viro 637574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 638574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 639574197e0SAl Viro path_put(&nd->path); 640574197e0SAl Viro return -ELOOP; 641574197e0SAl Viro } 642574197e0SAl Viro cond_resched(); 643574197e0SAl Viro current->total_link_count++; 644574197e0SAl Viro 64568ac1234SAl Viro touch_atime(link); 6461da177e4SLinus Torvalds nd_set_link(nd, NULL); 647cd4e91d3SAl Viro 64836f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 64936f3b4f6SAl Viro if (error) { 65036f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 65136f3b4f6SAl Viro path_put(&nd->path); 65236f3b4f6SAl Viro return error; 65336f3b4f6SAl Viro } 65436f3b4f6SAl Viro 65586acdca1SAl Viro nd->last_type = LAST_BIND; 656def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 657def4af30SAl Viro error = PTR_ERR(*p); 658def4af30SAl Viro if (!IS_ERR(*p)) { 6591da177e4SLinus Torvalds char *s = nd_get_link(nd); 660cc314eefSLinus Torvalds error = 0; 6611da177e4SLinus Torvalds if (s) 6621da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 663bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 66416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 665b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 666b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 667bcda7652SAl Viro /* stepped on a _really_ weird one */ 668bcda7652SAl Viro path_put(&nd->path); 669bcda7652SAl Viro error = -ELOOP; 670bcda7652SAl Viro } 671bcda7652SAl Viro } 6721da177e4SLinus Torvalds } 6731da177e4SLinus Torvalds return error; 6741da177e4SLinus Torvalds } 6751da177e4SLinus Torvalds 67631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 67731e6b01fSNick Piggin { 6780714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6790714a533SAl Viro struct mount *parent; 68031e6b01fSNick Piggin struct dentry *mountpoint; 68131e6b01fSNick Piggin 6820714a533SAl Viro parent = mnt->mnt_parent; 6830714a533SAl Viro if (&parent->mnt == path->mnt) 68431e6b01fSNick Piggin return 0; 685a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 68631e6b01fSNick Piggin path->dentry = mountpoint; 6870714a533SAl Viro path->mnt = &parent->mnt; 68831e6b01fSNick Piggin return 1; 68931e6b01fSNick Piggin } 69031e6b01fSNick Piggin 691bab77ebfSAl Viro int follow_up(struct path *path) 6921da177e4SLinus Torvalds { 6930714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6940714a533SAl Viro struct mount *parent; 6951da177e4SLinus Torvalds struct dentry *mountpoint; 69699b7db7bSNick Piggin 69799b7db7bSNick Piggin br_read_lock(vfsmount_lock); 6980714a533SAl Viro parent = mnt->mnt_parent; 6990714a533SAl Viro if (&parent->mnt == path->mnt) { 70099b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 7011da177e4SLinus Torvalds return 0; 7021da177e4SLinus Torvalds } 7030714a533SAl Viro mntget(&parent->mnt); 704a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 70599b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 706bab77ebfSAl Viro dput(path->dentry); 707bab77ebfSAl Viro path->dentry = mountpoint; 708bab77ebfSAl Viro mntput(path->mnt); 7090714a533SAl Viro path->mnt = &parent->mnt; 7101da177e4SLinus Torvalds return 1; 7111da177e4SLinus Torvalds } 7121da177e4SLinus Torvalds 713b5c84bf6SNick Piggin /* 7149875cf80SDavid Howells * Perform an automount 7159875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7169875cf80SDavid Howells * were called with. 7171da177e4SLinus Torvalds */ 7189875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7199875cf80SDavid Howells bool *need_mntput) 72031e6b01fSNick Piggin { 7219875cf80SDavid Howells struct vfsmount *mnt; 722ea5b778aSDavid Howells int err; 7239875cf80SDavid Howells 7249875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7259875cf80SDavid Howells return -EREMOTE; 7269875cf80SDavid Howells 7270ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 7280ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 7290ec26fd0SMiklos Szeredi * the name. 7300ec26fd0SMiklos Szeredi * 7310ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 7325a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 7330ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 7340ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 7350ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 7360ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 7375a30d8a2SDavid Howells */ 7385a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 739d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 7405a30d8a2SDavid Howells path->dentry->d_inode) 7419875cf80SDavid Howells return -EISDIR; 7420ec26fd0SMiklos Szeredi 7439875cf80SDavid Howells current->total_link_count++; 7449875cf80SDavid Howells if (current->total_link_count >= 40) 7459875cf80SDavid Howells return -ELOOP; 7469875cf80SDavid Howells 7479875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7489875cf80SDavid Howells if (IS_ERR(mnt)) { 7499875cf80SDavid Howells /* 7509875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7519875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7529875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7539875cf80SDavid Howells * 7549875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7559875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7569875cf80SDavid Howells * the path is inaccessible and we should say so. 7579875cf80SDavid Howells */ 75849084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 7599875cf80SDavid Howells return -EREMOTE; 7609875cf80SDavid Howells return PTR_ERR(mnt); 76131e6b01fSNick Piggin } 762ea5b778aSDavid Howells 7639875cf80SDavid Howells if (!mnt) /* mount collision */ 7649875cf80SDavid Howells return 0; 7659875cf80SDavid Howells 7668aef1884SAl Viro if (!*need_mntput) { 7678aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7688aef1884SAl Viro mntget(path->mnt); 7698aef1884SAl Viro *need_mntput = true; 7708aef1884SAl Viro } 77119a167afSAl Viro err = finish_automount(mnt, path); 772ea5b778aSDavid Howells 773ea5b778aSDavid Howells switch (err) { 774ea5b778aSDavid Howells case -EBUSY: 775ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 77619a167afSAl Viro return 0; 777ea5b778aSDavid Howells case 0: 7788aef1884SAl Viro path_put(path); 7799875cf80SDavid Howells path->mnt = mnt; 7809875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7819875cf80SDavid Howells return 0; 78219a167afSAl Viro default: 78319a167afSAl Viro return err; 7849875cf80SDavid Howells } 78519a167afSAl Viro 786ea5b778aSDavid Howells } 7879875cf80SDavid Howells 7889875cf80SDavid Howells /* 7899875cf80SDavid Howells * Handle a dentry that is managed in some way. 790cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7919875cf80SDavid Howells * - Flagged as mountpoint 7929875cf80SDavid Howells * - Flagged as automount point 7939875cf80SDavid Howells * 7949875cf80SDavid Howells * This may only be called in refwalk mode. 7959875cf80SDavid Howells * 7969875cf80SDavid Howells * Serialization is taken care of in namespace.c 7979875cf80SDavid Howells */ 7989875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7999875cf80SDavid Howells { 8008aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 8019875cf80SDavid Howells unsigned managed; 8029875cf80SDavid Howells bool need_mntput = false; 8038aef1884SAl Viro int ret = 0; 8049875cf80SDavid Howells 8059875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8069875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8079875cf80SDavid Howells * the components of that value change under us */ 8089875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8099875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8109875cf80SDavid Howells unlikely(managed != 0)) { 811cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 812cc53ce53SDavid Howells * being held. */ 813cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 814cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 815cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8161aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 817cc53ce53SDavid Howells if (ret < 0) 8188aef1884SAl Viro break; 819cc53ce53SDavid Howells } 820cc53ce53SDavid Howells 8219875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8229875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8239875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8249875cf80SDavid Howells if (mounted) { 8259875cf80SDavid Howells dput(path->dentry); 8269875cf80SDavid Howells if (need_mntput) 827463ffb2eSAl Viro mntput(path->mnt); 828463ffb2eSAl Viro path->mnt = mounted; 829463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8309875cf80SDavid Howells need_mntput = true; 8319875cf80SDavid Howells continue; 832463ffb2eSAl Viro } 833463ffb2eSAl Viro 8349875cf80SDavid Howells /* Something is mounted on this dentry in another 8359875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8369875cf80SDavid Howells * namespace got unmounted before we managed to get the 8379875cf80SDavid Howells * vfsmount_lock */ 8381da177e4SLinus Torvalds } 8399875cf80SDavid Howells 8409875cf80SDavid Howells /* Handle an automount point */ 8419875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8429875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8439875cf80SDavid Howells if (ret < 0) 8448aef1884SAl Viro break; 8459875cf80SDavid Howells continue; 8469875cf80SDavid Howells } 8479875cf80SDavid Howells 8489875cf80SDavid Howells /* We didn't change the current path point */ 8499875cf80SDavid Howells break; 8509875cf80SDavid Howells } 8518aef1884SAl Viro 8528aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8538aef1884SAl Viro mntput(path->mnt); 8548aef1884SAl Viro if (ret == -EISDIR) 8558aef1884SAl Viro ret = 0; 856a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 8571da177e4SLinus Torvalds } 8581da177e4SLinus Torvalds 859cc53ce53SDavid Howells int follow_down_one(struct path *path) 8601da177e4SLinus Torvalds { 8611da177e4SLinus Torvalds struct vfsmount *mounted; 8621da177e4SLinus Torvalds 8631c755af4SAl Viro mounted = lookup_mnt(path); 8641da177e4SLinus Torvalds if (mounted) { 8659393bd07SAl Viro dput(path->dentry); 8669393bd07SAl Viro mntput(path->mnt); 8679393bd07SAl Viro path->mnt = mounted; 8689393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8691da177e4SLinus Torvalds return 1; 8701da177e4SLinus Torvalds } 8711da177e4SLinus Torvalds return 0; 8721da177e4SLinus Torvalds } 8731da177e4SLinus Torvalds 87462a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 87562a7375eSIan Kent { 87662a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 87762a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 87862a7375eSIan Kent } 87962a7375eSIan Kent 8809875cf80SDavid Howells /* 881287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 882287548e4SAl Viro * we meet a managed dentry that would need blocking. 8839875cf80SDavid Howells */ 8849875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 885287548e4SAl Viro struct inode **inode) 8869875cf80SDavid Howells { 88762a7375eSIan Kent for (;;) { 888c7105365SAl Viro struct mount *mounted; 88962a7375eSIan Kent /* 89062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 89162a7375eSIan Kent * that wants to block transit. 89262a7375eSIan Kent */ 893287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 894ab90911fSDavid Howells return false; 89562a7375eSIan Kent 89662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 89762a7375eSIan Kent break; 89862a7375eSIan Kent 8999875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9009875cf80SDavid Howells if (!mounted) 9019875cf80SDavid Howells break; 902c7105365SAl Viro path->mnt = &mounted->mnt; 903c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 904a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 9059875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 90659430262SLinus Torvalds /* 90759430262SLinus Torvalds * Update the inode too. We don't need to re-check the 90859430262SLinus Torvalds * dentry sequence number here after this d_inode read, 90959430262SLinus Torvalds * because a mount-point is always pinned. 91059430262SLinus Torvalds */ 91159430262SLinus Torvalds *inode = path->dentry->d_inode; 9129875cf80SDavid Howells } 9139875cf80SDavid Howells return true; 9149875cf80SDavid Howells } 9159875cf80SDavid Howells 916dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 917287548e4SAl Viro { 918dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 919c7105365SAl Viro struct mount *mounted; 920dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 921287548e4SAl Viro if (!mounted) 922287548e4SAl Viro break; 923c7105365SAl Viro nd->path.mnt = &mounted->mnt; 924c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 925dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 926287548e4SAl Viro } 927287548e4SAl Viro } 928287548e4SAl Viro 92931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 93031e6b01fSNick Piggin { 93131e6b01fSNick Piggin set_root_rcu(nd); 93231e6b01fSNick Piggin 93331e6b01fSNick Piggin while (1) { 93431e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 93531e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 93631e6b01fSNick Piggin break; 93731e6b01fSNick Piggin } 93831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 93931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 94031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 94131e6b01fSNick Piggin unsigned seq; 94231e6b01fSNick Piggin 94331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 94431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 945ef7562d5SAl Viro goto failed; 94631e6b01fSNick Piggin nd->path.dentry = parent; 94731e6b01fSNick Piggin nd->seq = seq; 94831e6b01fSNick Piggin break; 94931e6b01fSNick Piggin } 95031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 95131e6b01fSNick Piggin break; 95231e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 95331e6b01fSNick Piggin } 954dea39376SAl Viro follow_mount_rcu(nd); 955dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 95631e6b01fSNick Piggin return 0; 957ef7562d5SAl Viro 958ef7562d5SAl Viro failed: 959ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9605b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 961ef7562d5SAl Viro nd->root.mnt = NULL; 962ef7562d5SAl Viro rcu_read_unlock(); 963ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 964ef7562d5SAl Viro return -ECHILD; 96531e6b01fSNick Piggin } 96631e6b01fSNick Piggin 9679875cf80SDavid Howells /* 968cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 969cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 970cc53ce53SDavid Howells * caller is permitted to proceed or not. 971cc53ce53SDavid Howells */ 9727cc90cc3SAl Viro int follow_down(struct path *path) 973cc53ce53SDavid Howells { 974cc53ce53SDavid Howells unsigned managed; 975cc53ce53SDavid Howells int ret; 976cc53ce53SDavid Howells 977cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 978cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 979cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 980cc53ce53SDavid Howells * being held. 981cc53ce53SDavid Howells * 982cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 983cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 984cc53ce53SDavid Howells * other than its daemon the right to mount on its 985cc53ce53SDavid Howells * superstructure. 986cc53ce53SDavid Howells * 987cc53ce53SDavid Howells * The filesystem may sleep at this point. 988cc53ce53SDavid Howells */ 989cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 990cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 991cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 992ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 9931aed3e42SAl Viro path->dentry, false); 994cc53ce53SDavid Howells if (ret < 0) 995cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 996cc53ce53SDavid Howells } 997cc53ce53SDavid Howells 998cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 999cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1000cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1001cc53ce53SDavid Howells if (!mounted) 1002cc53ce53SDavid Howells break; 1003cc53ce53SDavid Howells dput(path->dentry); 1004cc53ce53SDavid Howells mntput(path->mnt); 1005cc53ce53SDavid Howells path->mnt = mounted; 1006cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1007cc53ce53SDavid Howells continue; 1008cc53ce53SDavid Howells } 1009cc53ce53SDavid Howells 1010cc53ce53SDavid Howells /* Don't handle automount points here */ 1011cc53ce53SDavid Howells break; 1012cc53ce53SDavid Howells } 1013cc53ce53SDavid Howells return 0; 1014cc53ce53SDavid Howells } 1015cc53ce53SDavid Howells 1016cc53ce53SDavid Howells /* 10179875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10189875cf80SDavid Howells */ 10199875cf80SDavid Howells static void follow_mount(struct path *path) 10209875cf80SDavid Howells { 10219875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10229875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10239875cf80SDavid Howells if (!mounted) 10249875cf80SDavid Howells break; 10259875cf80SDavid Howells dput(path->dentry); 10269875cf80SDavid Howells mntput(path->mnt); 10279875cf80SDavid Howells path->mnt = mounted; 10289875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10299875cf80SDavid Howells } 10309875cf80SDavid Howells } 10319875cf80SDavid Howells 103231e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10331da177e4SLinus Torvalds { 10342a737871SAl Viro set_root(nd); 1035e518ddb7SAndreas Mohr 10361da177e4SLinus Torvalds while(1) { 10374ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10381da177e4SLinus Torvalds 10392a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10402a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10411da177e4SLinus Torvalds break; 10421da177e4SLinus Torvalds } 10434ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10443088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10453088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10461da177e4SLinus Torvalds dput(old); 10471da177e4SLinus Torvalds break; 10481da177e4SLinus Torvalds } 10493088dd70SAl Viro if (!follow_up(&nd->path)) 10501da177e4SLinus Torvalds break; 10511da177e4SLinus Torvalds } 105279ed0226SAl Viro follow_mount(&nd->path); 105331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10541da177e4SLinus Torvalds } 10551da177e4SLinus Torvalds 10561da177e4SLinus Torvalds /* 1057baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1058baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1059baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1060baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1061baa03890SNick Piggin */ 1062baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1063baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1064baa03890SNick Piggin { 1065baa03890SNick Piggin struct inode *inode = parent->d_inode; 1066baa03890SNick Piggin struct dentry *dentry; 1067baa03890SNick Piggin struct dentry *old; 1068baa03890SNick Piggin 1069baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1070baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1071baa03890SNick Piggin return ERR_PTR(-ENOENT); 1072baa03890SNick Piggin 1073baa03890SNick Piggin dentry = d_alloc(parent, name); 1074baa03890SNick Piggin if (unlikely(!dentry)) 1075baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1076baa03890SNick Piggin 1077baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1078baa03890SNick Piggin if (unlikely(old)) { 1079baa03890SNick Piggin dput(dentry); 1080baa03890SNick Piggin dentry = old; 1081baa03890SNick Piggin } 1082baa03890SNick Piggin return dentry; 1083baa03890SNick Piggin } 1084baa03890SNick Piggin 1085baa03890SNick Piggin /* 108644396f4bSJosef Bacik * We already have a dentry, but require a lookup to be performed on the parent 108744396f4bSJosef Bacik * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. 108844396f4bSJosef Bacik * parent->d_inode->i_mutex must be held. d_lookup must have verified that no 108944396f4bSJosef Bacik * child exists while under i_mutex. 109044396f4bSJosef Bacik */ 109144396f4bSJosef Bacik static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, 109244396f4bSJosef Bacik struct nameidata *nd) 109344396f4bSJosef Bacik { 109444396f4bSJosef Bacik struct inode *inode = parent->d_inode; 109544396f4bSJosef Bacik struct dentry *old; 109644396f4bSJosef Bacik 109744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1098e188dc02SMiklos Szeredi if (unlikely(IS_DEADDIR(inode))) { 1099e188dc02SMiklos Szeredi dput(dentry); 110044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1101e188dc02SMiklos Szeredi } 110244396f4bSJosef Bacik 110344396f4bSJosef Bacik old = inode->i_op->lookup(inode, dentry, nd); 110444396f4bSJosef Bacik if (unlikely(old)) { 110544396f4bSJosef Bacik dput(dentry); 110644396f4bSJosef Bacik dentry = old; 110744396f4bSJosef Bacik } 110844396f4bSJosef Bacik return dentry; 110944396f4bSJosef Bacik } 111044396f4bSJosef Bacik 111144396f4bSJosef Bacik /* 11121da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11131da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11141da177e4SLinus Torvalds * It _is_ time-critical. 11151da177e4SLinus Torvalds */ 11161da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 111731e6b01fSNick Piggin struct path *path, struct inode **inode) 11181da177e4SLinus Torvalds { 11194ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 112031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11215a18fff2SAl Viro int need_reval = 1; 11225a18fff2SAl Viro int status = 1; 11239875cf80SDavid Howells int err; 11249875cf80SDavid Howells 11253cac260aSAl Viro /* 1126b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1127b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1128b04f784eSNick Piggin * do the non-racy lookup, below. 1129b04f784eSNick Piggin */ 113031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 113131e6b01fSNick Piggin unsigned seq; 113231e6b01fSNick Piggin *inode = nd->inode; 113331e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11345a18fff2SAl Viro if (!dentry) 11355a18fff2SAl Viro goto unlazy; 11365a18fff2SAl Viro 113731e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 113831e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 113931e6b01fSNick Piggin return -ECHILD; 114031e6b01fSNick Piggin nd->seq = seq; 11415a18fff2SAl Viro 114224643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11435a18fff2SAl Viro status = d_revalidate(dentry, nd); 11445a18fff2SAl Viro if (unlikely(status <= 0)) { 11455a18fff2SAl Viro if (status != -ECHILD) 11465a18fff2SAl Viro need_reval = 0; 11475a18fff2SAl Viro goto unlazy; 11485a18fff2SAl Viro } 114924643087SAl Viro } 115044396f4bSJosef Bacik if (unlikely(d_need_lookup(dentry))) 115144396f4bSJosef Bacik goto unlazy; 115231e6b01fSNick Piggin path->mnt = mnt; 115331e6b01fSNick Piggin path->dentry = dentry; 1154d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1155d6e9bd25SAl Viro goto unlazy; 1156d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1157d6e9bd25SAl Viro goto unlazy; 11589875cf80SDavid Howells return 0; 11595a18fff2SAl Viro unlazy: 116019660af7SAl Viro if (unlazy_walk(nd, dentry)) 11615a18fff2SAl Viro return -ECHILD; 11625a18fff2SAl Viro } else { 116331e6b01fSNick Piggin dentry = __d_lookup(parent, name); 116424643087SAl Viro } 11655a18fff2SAl Viro 116644396f4bSJosef Bacik if (dentry && unlikely(d_need_lookup(dentry))) { 116744396f4bSJosef Bacik dput(dentry); 116844396f4bSJosef Bacik dentry = NULL; 116944396f4bSJosef Bacik } 11705a18fff2SAl Viro retry: 11715a18fff2SAl Viro if (unlikely(!dentry)) { 11725a18fff2SAl Viro struct inode *dir = parent->d_inode; 11735a18fff2SAl Viro BUG_ON(nd->inode != dir); 11745a18fff2SAl Viro 11755a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11765a18fff2SAl Viro dentry = d_lookup(parent, name); 11775a18fff2SAl Viro if (likely(!dentry)) { 11785a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 11795a18fff2SAl Viro if (IS_ERR(dentry)) { 11805a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11815a18fff2SAl Viro return PTR_ERR(dentry); 11825a18fff2SAl Viro } 11835a18fff2SAl Viro /* known good */ 11845a18fff2SAl Viro need_reval = 0; 11855a18fff2SAl Viro status = 1; 118644396f4bSJosef Bacik } else if (unlikely(d_need_lookup(dentry))) { 118744396f4bSJosef Bacik dentry = d_inode_lookup(parent, dentry, nd); 118844396f4bSJosef Bacik if (IS_ERR(dentry)) { 118944396f4bSJosef Bacik mutex_unlock(&dir->i_mutex); 119044396f4bSJosef Bacik return PTR_ERR(dentry); 119144396f4bSJosef Bacik } 119244396f4bSJosef Bacik /* known good */ 119344396f4bSJosef Bacik need_reval = 0; 119444396f4bSJosef Bacik status = 1; 11955a18fff2SAl Viro } 11965a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11975a18fff2SAl Viro } 11985a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 11995a18fff2SAl Viro status = d_revalidate(dentry, nd); 12005a18fff2SAl Viro if (unlikely(status <= 0)) { 12015a18fff2SAl Viro if (status < 0) { 12025a18fff2SAl Viro dput(dentry); 12035a18fff2SAl Viro return status; 12045a18fff2SAl Viro } 12055a18fff2SAl Viro if (!d_invalidate(dentry)) { 12065a18fff2SAl Viro dput(dentry); 12075a18fff2SAl Viro dentry = NULL; 12085a18fff2SAl Viro need_reval = 1; 12095a18fff2SAl Viro goto retry; 12105a18fff2SAl Viro } 12115a18fff2SAl Viro } 12125a18fff2SAl Viro 12131da177e4SLinus Torvalds path->mnt = mnt; 12141da177e4SLinus Torvalds path->dentry = dentry; 12159875cf80SDavid Howells err = follow_managed(path, nd->flags); 121689312214SIan Kent if (unlikely(err < 0)) { 121789312214SIan Kent path_put_conditional(path, nd); 12189875cf80SDavid Howells return err; 121989312214SIan Kent } 1220a3fbbde7SAl Viro if (err) 1221a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 122231e6b01fSNick Piggin *inode = path->dentry->d_inode; 12231da177e4SLinus Torvalds return 0; 12241da177e4SLinus Torvalds } 12251da177e4SLinus Torvalds 122652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 122752094c8aSAl Viro { 122852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 12294ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 123052094c8aSAl Viro if (err != -ECHILD) 123152094c8aSAl Viro return err; 123219660af7SAl Viro if (unlazy_walk(nd, NULL)) 123352094c8aSAl Viro return -ECHILD; 123452094c8aSAl Viro } 12354ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 123652094c8aSAl Viro } 123752094c8aSAl Viro 12389856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12399856fa1bSAl Viro { 12409856fa1bSAl Viro if (type == LAST_DOTDOT) { 12419856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12429856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12439856fa1bSAl Viro return -ECHILD; 12449856fa1bSAl Viro } else 12459856fa1bSAl Viro follow_dotdot(nd); 12469856fa1bSAl Viro } 12479856fa1bSAl Viro return 0; 12489856fa1bSAl Viro } 12499856fa1bSAl Viro 1250951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1251951361f9SAl Viro { 1252951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1253951361f9SAl Viro path_put(&nd->path); 1254951361f9SAl Viro } else { 1255951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12565b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1257951361f9SAl Viro nd->root.mnt = NULL; 1258951361f9SAl Viro rcu_read_unlock(); 1259951361f9SAl Viro br_read_unlock(vfsmount_lock); 1260951361f9SAl Viro } 1261951361f9SAl Viro } 1262951361f9SAl Viro 12633ddcd056SLinus Torvalds /* 12643ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 12653ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 12663ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 12673ddcd056SLinus Torvalds * for the common case. 12683ddcd056SLinus Torvalds */ 12697813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 12703ddcd056SLinus Torvalds { 12713ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 12723ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 12733ddcd056SLinus Torvalds return follow; 12743ddcd056SLinus Torvalds 12753ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 12763ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 12773ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 12783ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 12793ddcd056SLinus Torvalds } 12803ddcd056SLinus Torvalds return 0; 12813ddcd056SLinus Torvalds } 12823ddcd056SLinus Torvalds 1283ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1284ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1285ce57dfc1SAl Viro { 1286ce57dfc1SAl Viro struct inode *inode; 1287ce57dfc1SAl Viro int err; 1288ce57dfc1SAl Viro /* 1289ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1290ce57dfc1SAl Viro * to be able to know about the current root directory and 1291ce57dfc1SAl Viro * parent relationships. 1292ce57dfc1SAl Viro */ 1293ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1294ce57dfc1SAl Viro return handle_dots(nd, type); 1295ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1296ce57dfc1SAl Viro if (unlikely(err)) { 1297ce57dfc1SAl Viro terminate_walk(nd); 1298ce57dfc1SAl Viro return err; 1299ce57dfc1SAl Viro } 1300ce57dfc1SAl Viro if (!inode) { 1301ce57dfc1SAl Viro path_to_nameidata(path, nd); 1302ce57dfc1SAl Viro terminate_walk(nd); 1303ce57dfc1SAl Viro return -ENOENT; 1304ce57dfc1SAl Viro } 13057813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 130619660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 130719660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 130819660af7SAl Viro terminate_walk(nd); 1309ce57dfc1SAl Viro return -ECHILD; 131019660af7SAl Viro } 131119660af7SAl Viro } 1312ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1313ce57dfc1SAl Viro return 1; 1314ce57dfc1SAl Viro } 1315ce57dfc1SAl Viro path_to_nameidata(path, nd); 1316ce57dfc1SAl Viro nd->inode = inode; 1317ce57dfc1SAl Viro return 0; 1318ce57dfc1SAl Viro } 1319ce57dfc1SAl Viro 13201da177e4SLinus Torvalds /* 1321b356379aSAl Viro * This limits recursive symlink follows to 8, while 1322b356379aSAl Viro * limiting consecutive symlinks to 40. 1323b356379aSAl Viro * 1324b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1325b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1326b356379aSAl Viro */ 1327b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1328b356379aSAl Viro { 1329b356379aSAl Viro int res; 1330b356379aSAl Viro 1331b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1332b356379aSAl Viro path_put_conditional(path, nd); 1333b356379aSAl Viro path_put(&nd->path); 1334b356379aSAl Viro return -ELOOP; 1335b356379aSAl Viro } 13361a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1337b356379aSAl Viro 1338b356379aSAl Viro nd->depth++; 1339b356379aSAl Viro current->link_count++; 1340b356379aSAl Viro 1341b356379aSAl Viro do { 1342b356379aSAl Viro struct path link = *path; 1343b356379aSAl Viro void *cookie; 1344574197e0SAl Viro 1345574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1346b356379aSAl Viro if (!res) 1347b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1348b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1349574197e0SAl Viro put_link(nd, &link, cookie); 1350b356379aSAl Viro } while (res > 0); 1351b356379aSAl Viro 1352b356379aSAl Viro current->link_count--; 1353b356379aSAl Viro nd->depth--; 1354b356379aSAl Viro return res; 1355b356379aSAl Viro } 1356b356379aSAl Viro 1357b356379aSAl Viro /* 13583ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 13593ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 13603ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 13613ddcd056SLinus Torvalds * do lookup on this inode". 13623ddcd056SLinus Torvalds */ 13633ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 13643ddcd056SLinus Torvalds { 13653ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 13663ddcd056SLinus Torvalds return 1; 13673ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 13683ddcd056SLinus Torvalds return 0; 13693ddcd056SLinus Torvalds 13703ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 13713ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13723ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 13733ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13743ddcd056SLinus Torvalds return 1; 13753ddcd056SLinus Torvalds } 13763ddcd056SLinus Torvalds 1377bfcfaa77SLinus Torvalds /* 1378bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1379bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1380bfcfaa77SLinus Torvalds * 1381bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1382bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1383bfcfaa77SLinus Torvalds * fast. 1384bfcfaa77SLinus Torvalds * 1385bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1386bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1387bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1388bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1389bfcfaa77SLinus Torvalds * 1390bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1391bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1392bfcfaa77SLinus Torvalds * crossing operation. 1393bfcfaa77SLinus Torvalds * 1394bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1395bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1396bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1397bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1398bfcfaa77SLinus Torvalds */ 1399bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1400bfcfaa77SLinus Torvalds 1401bfcfaa77SLinus Torvalds #ifdef CONFIG_64BIT 1402bfcfaa77SLinus Torvalds 1403bfcfaa77SLinus Torvalds /* 1404bfcfaa77SLinus Torvalds * Jan Achrenius on G+: microoptimized version of 1405bfcfaa77SLinus Torvalds * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" 1406bfcfaa77SLinus Torvalds * that works for the bytemasks without having to 1407bfcfaa77SLinus Torvalds * mask them first. 1408bfcfaa77SLinus Torvalds */ 1409bfcfaa77SLinus Torvalds static inline long count_masked_bytes(unsigned long mask) 1410bfcfaa77SLinus Torvalds { 1411f7493e5dSLinus Torvalds return mask*0x0001020304050608ul >> 56; 1412bfcfaa77SLinus Torvalds } 1413bfcfaa77SLinus Torvalds 1414bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1415bfcfaa77SLinus Torvalds { 1416bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1417bfcfaa77SLinus Torvalds return hash; 1418bfcfaa77SLinus Torvalds } 1419bfcfaa77SLinus Torvalds 1420bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1421bfcfaa77SLinus Torvalds 1422bfcfaa77SLinus Torvalds /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ 1423bfcfaa77SLinus Torvalds static inline long count_masked_bytes(long mask) 1424bfcfaa77SLinus Torvalds { 1425bfcfaa77SLinus Torvalds /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ 1426bfcfaa77SLinus Torvalds long a = (0x0ff0001+mask) >> 23; 1427bfcfaa77SLinus Torvalds /* Fix the 1 for 00 case */ 1428bfcfaa77SLinus Torvalds return a & mask; 1429bfcfaa77SLinus Torvalds } 1430bfcfaa77SLinus Torvalds 1431bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1432bfcfaa77SLinus Torvalds 1433bfcfaa77SLinus Torvalds #endif 1434bfcfaa77SLinus Torvalds 1435bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1436bfcfaa77SLinus Torvalds { 1437bfcfaa77SLinus Torvalds unsigned long a, mask; 1438bfcfaa77SLinus Torvalds unsigned long hash = 0; 1439bfcfaa77SLinus Torvalds 1440bfcfaa77SLinus Torvalds for (;;) { 1441bfcfaa77SLinus Torvalds a = *(unsigned long *)name; 1442bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1443bfcfaa77SLinus Torvalds break; 1444bfcfaa77SLinus Torvalds hash += a; 1445f132c5beSAl Viro hash *= 9; 1446bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1447bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1448bfcfaa77SLinus Torvalds if (!len) 1449bfcfaa77SLinus Torvalds goto done; 1450bfcfaa77SLinus Torvalds } 1451bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1452bfcfaa77SLinus Torvalds hash += mask & a; 1453bfcfaa77SLinus Torvalds done: 1454bfcfaa77SLinus Torvalds return fold_hash(hash); 1455bfcfaa77SLinus Torvalds } 1456bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1457bfcfaa77SLinus Torvalds 1458989412bbSLinus Torvalds #define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) 1459989412bbSLinus Torvalds #define ONEBYTES REPEAT_BYTE(0x01) 1460989412bbSLinus Torvalds #define SLASHBYTES REPEAT_BYTE('/') 1461989412bbSLinus Torvalds #define HIGHBITS REPEAT_BYTE(0x80) 1462bfcfaa77SLinus Torvalds 1463bfcfaa77SLinus Torvalds /* Return the high bit set in the first byte that is a zero */ 1464bfcfaa77SLinus Torvalds static inline unsigned long has_zero(unsigned long a) 1465bfcfaa77SLinus Torvalds { 1466bfcfaa77SLinus Torvalds return ((a - ONEBYTES) & ~a) & HIGHBITS; 1467bfcfaa77SLinus Torvalds } 1468bfcfaa77SLinus Torvalds 1469bfcfaa77SLinus Torvalds /* 1470bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1471bfcfaa77SLinus Torvalds * return the length of the component; 1472bfcfaa77SLinus Torvalds */ 1473bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1474bfcfaa77SLinus Torvalds { 1475bfcfaa77SLinus Torvalds unsigned long a, mask, hash, len; 1476bfcfaa77SLinus Torvalds 1477bfcfaa77SLinus Torvalds hash = a = 0; 1478bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1479bfcfaa77SLinus Torvalds do { 1480bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1481bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1482bfcfaa77SLinus Torvalds a = *(unsigned long *)(name+len); 1483bfcfaa77SLinus Torvalds /* Do we have any NUL or '/' bytes in this word? */ 1484bfcfaa77SLinus Torvalds mask = has_zero(a) | has_zero(a ^ SLASHBYTES); 1485bfcfaa77SLinus Torvalds } while (!mask); 1486bfcfaa77SLinus Torvalds 1487bfcfaa77SLinus Torvalds /* The mask *below* the first high bit set */ 1488bfcfaa77SLinus Torvalds mask = (mask - 1) & ~mask; 1489bfcfaa77SLinus Torvalds mask >>= 7; 1490bfcfaa77SLinus Torvalds hash += a & mask; 1491bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1492bfcfaa77SLinus Torvalds 1493bfcfaa77SLinus Torvalds return len + count_masked_bytes(mask); 1494bfcfaa77SLinus Torvalds } 1495bfcfaa77SLinus Torvalds 1496bfcfaa77SLinus Torvalds #else 1497bfcfaa77SLinus Torvalds 14980145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 14990145acc2SLinus Torvalds { 15000145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 15010145acc2SLinus Torvalds while (len--) 15020145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 15030145acc2SLinus Torvalds return end_name_hash(hash); 15040145acc2SLinus Torvalds } 1505ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 15060145acc2SLinus Torvalds 15073ddcd056SLinus Torvalds /* 1508200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1509200e9ef7SLinus Torvalds * one character. 1510200e9ef7SLinus Torvalds */ 1511200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1512200e9ef7SLinus Torvalds { 1513200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1514200e9ef7SLinus Torvalds unsigned long len = 0, c; 1515200e9ef7SLinus Torvalds 1516200e9ef7SLinus Torvalds c = (unsigned char)*name; 1517200e9ef7SLinus Torvalds do { 1518200e9ef7SLinus Torvalds len++; 1519200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1520200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1521200e9ef7SLinus Torvalds } while (c && c != '/'); 1522200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1523200e9ef7SLinus Torvalds return len; 1524200e9ef7SLinus Torvalds } 1525200e9ef7SLinus Torvalds 1526bfcfaa77SLinus Torvalds #endif 1527bfcfaa77SLinus Torvalds 1528200e9ef7SLinus Torvalds /* 15291da177e4SLinus Torvalds * Name resolution. 1530ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1531ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 15321da177e4SLinus Torvalds * 1533ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1534ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 15351da177e4SLinus Torvalds */ 15366de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 15371da177e4SLinus Torvalds { 15381da177e4SLinus Torvalds struct path next; 15391da177e4SLinus Torvalds int err; 15401da177e4SLinus Torvalds 15411da177e4SLinus Torvalds while (*name=='/') 15421da177e4SLinus Torvalds name++; 15431da177e4SLinus Torvalds if (!*name) 1544086e183aSAl Viro return 0; 15451da177e4SLinus Torvalds 15461da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 15471da177e4SLinus Torvalds for(;;) { 15481da177e4SLinus Torvalds struct qstr this; 1549200e9ef7SLinus Torvalds long len; 1550fe479a58SAl Viro int type; 15511da177e4SLinus Torvalds 155252094c8aSAl Viro err = may_lookup(nd); 15531da177e4SLinus Torvalds if (err) 15541da177e4SLinus Torvalds break; 15551da177e4SLinus Torvalds 1556200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 15571da177e4SLinus Torvalds this.name = name; 1558200e9ef7SLinus Torvalds this.len = len; 15591da177e4SLinus Torvalds 1560fe479a58SAl Viro type = LAST_NORM; 1561200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1562fe479a58SAl Viro case 2: 1563200e9ef7SLinus Torvalds if (name[1] == '.') { 1564fe479a58SAl Viro type = LAST_DOTDOT; 156516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 156616c2cd71SAl Viro } 1567fe479a58SAl Viro break; 1568fe479a58SAl Viro case 1: 1569fe479a58SAl Viro type = LAST_DOT; 1570fe479a58SAl Viro } 15715a202bcdSAl Viro if (likely(type == LAST_NORM)) { 15725a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 157316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 15745a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 15755a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 15765a202bcdSAl Viro &this); 15775a202bcdSAl Viro if (err < 0) 15785a202bcdSAl Viro break; 15795a202bcdSAl Viro } 15805a202bcdSAl Viro } 1581fe479a58SAl Viro 1582200e9ef7SLinus Torvalds if (!name[len]) 15831da177e4SLinus Torvalds goto last_component; 1584200e9ef7SLinus Torvalds /* 1585200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1586200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1587200e9ef7SLinus Torvalds */ 1588200e9ef7SLinus Torvalds do { 1589200e9ef7SLinus Torvalds len++; 1590200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1591200e9ef7SLinus Torvalds if (!name[len]) 1592b356379aSAl Viro goto last_component; 1593200e9ef7SLinus Torvalds name += len; 15941da177e4SLinus Torvalds 1595ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1596ce57dfc1SAl Viro if (err < 0) 1597ce57dfc1SAl Viro return err; 1598fe479a58SAl Viro 1599ce57dfc1SAl Viro if (err) { 1600b356379aSAl Viro err = nested_symlink(&next, nd); 16011da177e4SLinus Torvalds if (err) 1602a7472babSAl Viro return err; 160331e6b01fSNick Piggin } 16043ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 16051da177e4SLinus Torvalds continue; 16063ddcd056SLinus Torvalds err = -ENOTDIR; 16073ddcd056SLinus Torvalds break; 16081da177e4SLinus Torvalds /* here ends the main loop */ 16091da177e4SLinus Torvalds 16101da177e4SLinus Torvalds last_component: 1611ce57dfc1SAl Viro nd->last = this; 1612ce57dfc1SAl Viro nd->last_type = type; 1613ce57dfc1SAl Viro return 0; 1614ce57dfc1SAl Viro } 1615951361f9SAl Viro terminate_walk(nd); 16161da177e4SLinus Torvalds return err; 16171da177e4SLinus Torvalds } 16181da177e4SLinus Torvalds 161970e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 162070e9b357SAl Viro struct nameidata *nd, struct file **fp) 162131e6b01fSNick Piggin { 162231e6b01fSNick Piggin int retval = 0; 162331e6b01fSNick Piggin int fput_needed; 162431e6b01fSNick Piggin struct file *file; 162531e6b01fSNick Piggin 162631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 162716c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 162831e6b01fSNick Piggin nd->depth = 0; 16295b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 16305b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 163173d049a4SAl Viro if (*name) { 16325b6ca027SAl Viro if (!inode->i_op->lookup) 16335b6ca027SAl Viro return -ENOTDIR; 16345b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 16355b6ca027SAl Viro if (retval) 16365b6ca027SAl Viro return retval; 163773d049a4SAl Viro } 16385b6ca027SAl Viro nd->path = nd->root; 16395b6ca027SAl Viro nd->inode = inode; 16405b6ca027SAl Viro if (flags & LOOKUP_RCU) { 16415b6ca027SAl Viro br_read_lock(vfsmount_lock); 16425b6ca027SAl Viro rcu_read_lock(); 16435b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 16445b6ca027SAl Viro } else { 16455b6ca027SAl Viro path_get(&nd->path); 16465b6ca027SAl Viro } 16475b6ca027SAl Viro return 0; 16485b6ca027SAl Viro } 16495b6ca027SAl Viro 165031e6b01fSNick Piggin nd->root.mnt = NULL; 165131e6b01fSNick Piggin 165231e6b01fSNick Piggin if (*name=='/') { 1653e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 165431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 165531e6b01fSNick Piggin rcu_read_lock(); 1656e41f7d4eSAl Viro set_root_rcu(nd); 1657e41f7d4eSAl Viro } else { 1658e41f7d4eSAl Viro set_root(nd); 1659e41f7d4eSAl Viro path_get(&nd->root); 1660e41f7d4eSAl Viro } 166131e6b01fSNick Piggin nd->path = nd->root; 166231e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1663e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 166431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1665c28cc364SNick Piggin unsigned seq; 166631e6b01fSNick Piggin 166731e6b01fSNick Piggin br_read_lock(vfsmount_lock); 166831e6b01fSNick Piggin rcu_read_lock(); 166931e6b01fSNick Piggin 1670c28cc364SNick Piggin do { 1671c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 167231e6b01fSNick Piggin nd->path = fs->pwd; 1673c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1674c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1675e41f7d4eSAl Viro } else { 1676e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1677e41f7d4eSAl Viro } 167831e6b01fSNick Piggin } else { 167931e6b01fSNick Piggin struct dentry *dentry; 168031e6b01fSNick Piggin 16811abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 168231e6b01fSNick Piggin retval = -EBADF; 168331e6b01fSNick Piggin if (!file) 168431e6b01fSNick Piggin goto out_fail; 168531e6b01fSNick Piggin 168631e6b01fSNick Piggin dentry = file->f_path.dentry; 168731e6b01fSNick Piggin 1688f52e0c11SAl Viro if (*name) { 168931e6b01fSNick Piggin retval = -ENOTDIR; 169031e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 169131e6b01fSNick Piggin goto fput_fail; 169231e6b01fSNick Piggin 16934ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 169431e6b01fSNick Piggin if (retval) 169531e6b01fSNick Piggin goto fput_fail; 1696f52e0c11SAl Viro } 169731e6b01fSNick Piggin 169831e6b01fSNick Piggin nd->path = file->f_path; 1699e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 170031e6b01fSNick Piggin if (fput_needed) 170170e9b357SAl Viro *fp = file; 1702c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 170331e6b01fSNick Piggin br_read_lock(vfsmount_lock); 170431e6b01fSNick Piggin rcu_read_lock(); 17055590ff0dSUlrich Drepper } else { 17065dd784d0SJan Blunck path_get(&file->f_path); 17075590ff0dSUlrich Drepper fput_light(file, fput_needed); 17081da177e4SLinus Torvalds } 1709e41f7d4eSAl Viro } 1710e41f7d4eSAl Viro 171131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17129b4a9b14SAl Viro return 0; 17132dfdd266SJosef 'Jeff' Sipek 17149b4a9b14SAl Viro fput_fail: 17159b4a9b14SAl Viro fput_light(file, fput_needed); 17169b4a9b14SAl Viro out_fail: 17179b4a9b14SAl Viro return retval; 17189b4a9b14SAl Viro } 17199b4a9b14SAl Viro 1720bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1721bd92d7feSAl Viro { 1722bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1723bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1724bd92d7feSAl Viro 1725bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1726bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1727bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1728bd92d7feSAl Viro } 1729bd92d7feSAl Viro 17309b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1731ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 17329b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17339b4a9b14SAl Viro { 173470e9b357SAl Viro struct file *base = NULL; 1735bd92d7feSAl Viro struct path path; 1736bd92d7feSAl Viro int err; 173731e6b01fSNick Piggin 173831e6b01fSNick Piggin /* 173931e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 174031e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 174131e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 174231e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 174331e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 174431e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 174531e6b01fSNick Piggin * analogue, foo_rcu(). 174631e6b01fSNick Piggin * 174731e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 174831e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 174931e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 175031e6b01fSNick Piggin * be able to complete). 175131e6b01fSNick Piggin */ 1752bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1753ee0827cdSAl Viro 1754bd92d7feSAl Viro if (unlikely(err)) 1755bd92d7feSAl Viro return err; 1756ee0827cdSAl Viro 1757ee0827cdSAl Viro current->total_link_count = 0; 1758bd92d7feSAl Viro err = link_path_walk(name, nd); 1759bd92d7feSAl Viro 1760bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1761bd92d7feSAl Viro err = lookup_last(nd, &path); 1762bd92d7feSAl Viro while (err > 0) { 1763bd92d7feSAl Viro void *cookie; 1764bd92d7feSAl Viro struct path link = path; 1765bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1766574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1767bd92d7feSAl Viro if (!err) 1768bd92d7feSAl Viro err = lookup_last(nd, &path); 1769574197e0SAl Viro put_link(nd, &link, cookie); 1770bd92d7feSAl Viro } 1771bd92d7feSAl Viro } 1772ee0827cdSAl Viro 17739f1fafeeSAl Viro if (!err) 17749f1fafeeSAl Viro err = complete_walk(nd); 1775bd92d7feSAl Viro 1776bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1777bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1778bd92d7feSAl Viro path_put(&nd->path); 1779bd23a539SAl Viro err = -ENOTDIR; 1780bd92d7feSAl Viro } 1781bd92d7feSAl Viro } 178216c2cd71SAl Viro 178370e9b357SAl Viro if (base) 178470e9b357SAl Viro fput(base); 1785ee0827cdSAl Viro 17865b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 178731e6b01fSNick Piggin path_put(&nd->root); 178831e6b01fSNick Piggin nd->root.mnt = NULL; 178931e6b01fSNick Piggin } 1790bd92d7feSAl Viro return err; 179131e6b01fSNick Piggin } 179231e6b01fSNick Piggin 1793ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1794ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1795ee0827cdSAl Viro { 1796ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1797ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1798ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1799ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1800ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1801ee0827cdSAl Viro 180231e6b01fSNick Piggin if (likely(!retval)) { 180331e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 180431e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 180531e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 180631e6b01fSNick Piggin } 180731e6b01fSNick Piggin } 1808170aa3d0SUlrich Drepper return retval; 18091da177e4SLinus Torvalds } 18101da177e4SLinus Torvalds 1811c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 18125590ff0dSUlrich Drepper { 1813c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 18145590ff0dSUlrich Drepper } 18155590ff0dSUlrich Drepper 1816d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1817d1811465SAl Viro { 1818d1811465SAl Viro struct nameidata nd; 1819d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1820d1811465SAl Viro if (!res) 1821d1811465SAl Viro *path = nd.path; 1822d1811465SAl Viro return res; 1823d1811465SAl Viro } 1824d1811465SAl Viro 182516f18200SJosef 'Jeff' Sipek /** 182616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 182716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 182816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 182916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 183016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1831e0a01249SAl Viro * @path: pointer to struct path to fill 183216f18200SJosef 'Jeff' Sipek */ 183316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 183416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1835e0a01249SAl Viro struct path *path) 183616f18200SJosef 'Jeff' Sipek { 1837e0a01249SAl Viro struct nameidata nd; 1838e0a01249SAl Viro int err; 1839e0a01249SAl Viro nd.root.dentry = dentry; 1840e0a01249SAl Viro nd.root.mnt = mnt; 1841e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18425b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1843e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1844e0a01249SAl Viro if (!err) 1845e0a01249SAl Viro *path = nd.path; 1846e0a01249SAl Viro return err; 184716f18200SJosef 'Jeff' Sipek } 184816f18200SJosef 'Jeff' Sipek 1849eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1850eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 18511da177e4SLinus Torvalds { 185281fca444SChristoph Hellwig struct inode *inode = base->d_inode; 18531da177e4SLinus Torvalds struct dentry *dentry; 18541da177e4SLinus Torvalds int err; 18551da177e4SLinus Torvalds 18564ad5abb3SAl Viro err = inode_permission(inode, MAY_EXEC); 185781fca444SChristoph Hellwig if (err) 185881fca444SChristoph Hellwig return ERR_PTR(err); 18591da177e4SLinus Torvalds 18601da177e4SLinus Torvalds /* 1861b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1862b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1863b04f784eSNick Piggin * a double lookup. 18646e6b1bd1SAl Viro */ 18656e6b1bd1SAl Viro dentry = d_lookup(base, name); 18666e6b1bd1SAl Viro 186744396f4bSJosef Bacik if (dentry && d_need_lookup(dentry)) { 186844396f4bSJosef Bacik /* 186944396f4bSJosef Bacik * __lookup_hash is called with the parent dir's i_mutex already 187044396f4bSJosef Bacik * held, so we are good to go here. 187144396f4bSJosef Bacik */ 187244396f4bSJosef Bacik dentry = d_inode_lookup(base, dentry, nd); 187344396f4bSJosef Bacik if (IS_ERR(dentry)) 187444396f4bSJosef Bacik return dentry; 187544396f4bSJosef Bacik } 187644396f4bSJosef Bacik 1877d2d9e9fbSAl Viro if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { 1878d2d9e9fbSAl Viro int status = d_revalidate(dentry, nd); 1879d2d9e9fbSAl Viro if (unlikely(status <= 0)) { 1880d2d9e9fbSAl Viro /* 1881d2d9e9fbSAl Viro * The dentry failed validation. 1882d2d9e9fbSAl Viro * If d_revalidate returned 0 attempt to invalidate 1883d2d9e9fbSAl Viro * the dentry otherwise d_revalidate is asking us 1884d2d9e9fbSAl Viro * to return a fail status. 1885d2d9e9fbSAl Viro */ 1886d2d9e9fbSAl Viro if (status < 0) { 1887d2d9e9fbSAl Viro dput(dentry); 1888d2d9e9fbSAl Viro return ERR_PTR(status); 1889d2d9e9fbSAl Viro } else if (!d_invalidate(dentry)) { 1890d2d9e9fbSAl Viro dput(dentry); 1891d2d9e9fbSAl Viro dentry = NULL; 1892d2d9e9fbSAl Viro } 1893d2d9e9fbSAl Viro } 1894d2d9e9fbSAl Viro } 18956e6b1bd1SAl Viro 18961da177e4SLinus Torvalds if (!dentry) 1897baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 18985a202bcdSAl Viro 18991da177e4SLinus Torvalds return dentry; 19001da177e4SLinus Torvalds } 19011da177e4SLinus Torvalds 1902057f6c01SJames Morris /* 1903057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1904057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1905057f6c01SJames Morris * SMP-safe. 1906057f6c01SJames Morris */ 1907a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 19081da177e4SLinus Torvalds { 19094ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 19101da177e4SLinus Torvalds } 19111da177e4SLinus Torvalds 1912eead1911SChristoph Hellwig /** 1913a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1914eead1911SChristoph Hellwig * @name: pathname component to lookup 1915eead1911SChristoph Hellwig * @base: base directory to lookup from 1916eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1917eead1911SChristoph Hellwig * 1918a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1919a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1920eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1921eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1922eead1911SChristoph Hellwig */ 1923057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1924057f6c01SJames Morris { 1925057f6c01SJames Morris struct qstr this; 19266a96ba54SAl Viro unsigned int c; 1927057f6c01SJames Morris 19282f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 19292f9092e1SDavid Woodhouse 19306a96ba54SAl Viro this.name = name; 19316a96ba54SAl Viro this.len = len; 19320145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 19336a96ba54SAl Viro if (!len) 19346a96ba54SAl Viro return ERR_PTR(-EACCES); 19356a96ba54SAl Viro 19366a96ba54SAl Viro while (len--) { 19376a96ba54SAl Viro c = *(const unsigned char *)name++; 19386a96ba54SAl Viro if (c == '/' || c == '\0') 19396a96ba54SAl Viro return ERR_PTR(-EACCES); 19406a96ba54SAl Viro } 19415a202bcdSAl Viro /* 19425a202bcdSAl Viro * See if the low-level filesystem might want 19435a202bcdSAl Viro * to use its own hash.. 19445a202bcdSAl Viro */ 19455a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 19465a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 19475a202bcdSAl Viro if (err < 0) 19485a202bcdSAl Viro return ERR_PTR(err); 19495a202bcdSAl Viro } 1950eead1911SChristoph Hellwig 195149705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1952057f6c01SJames Morris } 1953057f6c01SJames Morris 19541fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 19551fa1e7f6SAndy Whitcroft struct path *path, int *empty) 19561da177e4SLinus Torvalds { 19572d8f3038SAl Viro struct nameidata nd; 19581fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 19591da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19601da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19612d8f3038SAl Viro 19622d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19632d8f3038SAl Viro 19642d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19651da177e4SLinus Torvalds putname(tmp); 19662d8f3038SAl Viro if (!err) 19672d8f3038SAl Viro *path = nd.path; 19681da177e4SLinus Torvalds } 19691da177e4SLinus Torvalds return err; 19701da177e4SLinus Torvalds } 19711da177e4SLinus Torvalds 19721fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 19731fa1e7f6SAndy Whitcroft struct path *path) 19741fa1e7f6SAndy Whitcroft { 1975f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 19761fa1e7f6SAndy Whitcroft } 19771fa1e7f6SAndy Whitcroft 19782ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 19792ad94ae6SAl Viro struct nameidata *nd, char **name) 19802ad94ae6SAl Viro { 19812ad94ae6SAl Viro char *s = getname(path); 19822ad94ae6SAl Viro int error; 19832ad94ae6SAl Viro 19842ad94ae6SAl Viro if (IS_ERR(s)) 19852ad94ae6SAl Viro return PTR_ERR(s); 19862ad94ae6SAl Viro 19872ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 19882ad94ae6SAl Viro if (error) 19892ad94ae6SAl Viro putname(s); 19902ad94ae6SAl Viro else 19912ad94ae6SAl Viro *name = s; 19922ad94ae6SAl Viro 19932ad94ae6SAl Viro return error; 19942ad94ae6SAl Viro } 19952ad94ae6SAl Viro 19961da177e4SLinus Torvalds /* 19971da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 19981da177e4SLinus Torvalds * minimal. 19991da177e4SLinus Torvalds */ 20001da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 20011da177e4SLinus Torvalds { 2002da9592edSDavid Howells uid_t fsuid = current_fsuid(); 2003da9592edSDavid Howells 20041da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 20051da177e4SLinus Torvalds return 0; 2006e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 2007e795b717SSerge E. Hallyn goto other_userns; 2008da9592edSDavid Howells if (inode->i_uid == fsuid) 20091da177e4SLinus Torvalds return 0; 2010da9592edSDavid Howells if (dir->i_uid == fsuid) 20111da177e4SLinus Torvalds return 0; 2012e795b717SSerge E. Hallyn 2013e795b717SSerge E. Hallyn other_userns: 2014e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 20151da177e4SLinus Torvalds } 20161da177e4SLinus Torvalds 20171da177e4SLinus Torvalds /* 20181da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 20191da177e4SLinus Torvalds * whether the type of victim is right. 20201da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 20211da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 20221da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 20231da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 20241da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 20251da177e4SLinus Torvalds * a. be owner of dir, or 20261da177e4SLinus Torvalds * b. be owner of victim, or 20271da177e4SLinus Torvalds * c. have CAP_FOWNER capability 20281da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 20291da177e4SLinus Torvalds * links pointing to it. 20301da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 20311da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 20321da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 20331da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 20341da177e4SLinus Torvalds * nfs_async_unlink(). 20351da177e4SLinus Torvalds */ 2036858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 20371da177e4SLinus Torvalds { 20381da177e4SLinus Torvalds int error; 20391da177e4SLinus Torvalds 20401da177e4SLinus Torvalds if (!victim->d_inode) 20411da177e4SLinus Torvalds return -ENOENT; 20421da177e4SLinus Torvalds 20431da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2044cccc6bbaSAl Viro audit_inode_child(victim, dir); 20451da177e4SLinus Torvalds 2046f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20471da177e4SLinus Torvalds if (error) 20481da177e4SLinus Torvalds return error; 20491da177e4SLinus Torvalds if (IS_APPEND(dir)) 20501da177e4SLinus Torvalds return -EPERM; 20511da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2052f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20531da177e4SLinus Torvalds return -EPERM; 20541da177e4SLinus Torvalds if (isdir) { 20551da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20561da177e4SLinus Torvalds return -ENOTDIR; 20571da177e4SLinus Torvalds if (IS_ROOT(victim)) 20581da177e4SLinus Torvalds return -EBUSY; 20591da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20601da177e4SLinus Torvalds return -EISDIR; 20611da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20621da177e4SLinus Torvalds return -ENOENT; 20631da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20641da177e4SLinus Torvalds return -EBUSY; 20651da177e4SLinus Torvalds return 0; 20661da177e4SLinus Torvalds } 20671da177e4SLinus Torvalds 20681da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20691da177e4SLinus Torvalds * dir. 20701da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20711da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20721da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20731da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20741da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20751da177e4SLinus Torvalds */ 2076a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 20771da177e4SLinus Torvalds { 20781da177e4SLinus Torvalds if (child->d_inode) 20791da177e4SLinus Torvalds return -EEXIST; 20801da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20811da177e4SLinus Torvalds return -ENOENT; 2082f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 20831da177e4SLinus Torvalds } 20841da177e4SLinus Torvalds 20851da177e4SLinus Torvalds /* 20861da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 20871da177e4SLinus Torvalds */ 20881da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 20891da177e4SLinus Torvalds { 20901da177e4SLinus Torvalds struct dentry *p; 20911da177e4SLinus Torvalds 20921da177e4SLinus Torvalds if (p1 == p2) { 2093f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 20941da177e4SLinus Torvalds return NULL; 20951da177e4SLinus Torvalds } 20961da177e4SLinus Torvalds 2097a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20981da177e4SLinus Torvalds 2099e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2100e2761a11SOGAWA Hirofumi if (p) { 2101f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2102f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 21031da177e4SLinus Torvalds return p; 21041da177e4SLinus Torvalds } 21051da177e4SLinus Torvalds 2106e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2107e2761a11SOGAWA Hirofumi if (p) { 2108f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2109f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 21101da177e4SLinus Torvalds return p; 21111da177e4SLinus Torvalds } 21121da177e4SLinus Torvalds 2113f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2114f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 21151da177e4SLinus Torvalds return NULL; 21161da177e4SLinus Torvalds } 21171da177e4SLinus Torvalds 21181da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 21191da177e4SLinus Torvalds { 21201b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 21211da177e4SLinus Torvalds if (p1 != p2) { 21221b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2123a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 21241da177e4SLinus Torvalds } 21251da177e4SLinus Torvalds } 21261da177e4SLinus Torvalds 21274acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 21281da177e4SLinus Torvalds struct nameidata *nd) 21291da177e4SLinus Torvalds { 2130a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 21311da177e4SLinus Torvalds 21321da177e4SLinus Torvalds if (error) 21331da177e4SLinus Torvalds return error; 21341da177e4SLinus Torvalds 2135acfa4380SAl Viro if (!dir->i_op->create) 21361da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 21371da177e4SLinus Torvalds mode &= S_IALLUGO; 21381da177e4SLinus Torvalds mode |= S_IFREG; 21391da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 21401da177e4SLinus Torvalds if (error) 21411da177e4SLinus Torvalds return error; 21421da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 2143a74574aaSStephen Smalley if (!error) 2144f38aa942SAmy Griffis fsnotify_create(dir, dentry); 21451da177e4SLinus Torvalds return error; 21461da177e4SLinus Torvalds } 21471da177e4SLinus Torvalds 214873d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 21491da177e4SLinus Torvalds { 21503fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21511da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21521da177e4SLinus Torvalds int error; 21531da177e4SLinus Torvalds 2154bcda7652SAl Viro /* O_PATH? */ 2155bcda7652SAl Viro if (!acc_mode) 2156bcda7652SAl Viro return 0; 2157bcda7652SAl Viro 21581da177e4SLinus Torvalds if (!inode) 21591da177e4SLinus Torvalds return -ENOENT; 21601da177e4SLinus Torvalds 2161c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2162c8fe8f30SChristoph Hellwig case S_IFLNK: 21631da177e4SLinus Torvalds return -ELOOP; 2164c8fe8f30SChristoph Hellwig case S_IFDIR: 2165c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21661da177e4SLinus Torvalds return -EISDIR; 2167c8fe8f30SChristoph Hellwig break; 2168c8fe8f30SChristoph Hellwig case S_IFBLK: 2169c8fe8f30SChristoph Hellwig case S_IFCHR: 21703fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21711da177e4SLinus Torvalds return -EACCES; 2172c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2173c8fe8f30SChristoph Hellwig case S_IFIFO: 2174c8fe8f30SChristoph Hellwig case S_IFSOCK: 21751da177e4SLinus Torvalds flag &= ~O_TRUNC; 2176c8fe8f30SChristoph Hellwig break; 21774a3fd211SDave Hansen } 2178b41572e9SDave Hansen 21793fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2180b41572e9SDave Hansen if (error) 2181b41572e9SDave Hansen return error; 21826146f0d5SMimi Zohar 21831da177e4SLinus Torvalds /* 21841da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 21851da177e4SLinus Torvalds */ 21861da177e4SLinus Torvalds if (IS_APPEND(inode)) { 21878737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 21887715b521SAl Viro return -EPERM; 21891da177e4SLinus Torvalds if (flag & O_TRUNC) 21907715b521SAl Viro return -EPERM; 21911da177e4SLinus Torvalds } 21921da177e4SLinus Torvalds 21931da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 21942e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 21957715b521SAl Viro return -EPERM; 21961da177e4SLinus Torvalds 2197f3c7691eSJ. Bruce Fields return 0; 21987715b521SAl Viro } 21997715b521SAl Viro 2200e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 22017715b521SAl Viro { 2202e1181ee6SJeff Layton struct path *path = &filp->f_path; 22037715b521SAl Viro struct inode *inode = path->dentry->d_inode; 22047715b521SAl Viro int error = get_write_access(inode); 22051da177e4SLinus Torvalds if (error) 22067715b521SAl Viro return error; 22071da177e4SLinus Torvalds /* 22081da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 22091da177e4SLinus Torvalds */ 22101da177e4SLinus Torvalds error = locks_verify_locked(inode); 2211be6d3e56SKentaro Takeda if (!error) 2212ea0d3ab2STetsuo Handa error = security_path_truncate(path); 22131da177e4SLinus Torvalds if (!error) { 22147715b521SAl Viro error = do_truncate(path->dentry, 0, 2215d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2216e1181ee6SJeff Layton filp); 22171da177e4SLinus Torvalds } 22181da177e4SLinus Torvalds put_write_access(inode); 2219acd0c935SMimi Zohar return error; 22201da177e4SLinus Torvalds } 22211da177e4SLinus Torvalds 2222d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2223d57999e1SDave Hansen { 22248a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 22258a5e929dSAl Viro flag--; 2226d57999e1SDave Hansen return flag; 2227d57999e1SDave Hansen } 2228d57999e1SDave Hansen 222931e6b01fSNick Piggin /* 2230fe2d35ffSAl Viro * Handle the last step of open() 223131e6b01fSNick Piggin */ 2232fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2233c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2234fb1cc555SAl Viro { 2235a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 22366c0d46c4SAl Viro struct dentry *dentry; 2237ca344a89SAl Viro int open_flag = op->open_flag; 22386c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2239ca344a89SAl Viro int want_write = 0; 2240bcda7652SAl Viro int acc_mode = op->acc_mode; 2241fb1cc555SAl Viro struct file *filp; 224216c2cd71SAl Viro int error; 2243fb1cc555SAl Viro 2244c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2245c3e380b0SAl Viro nd->flags |= op->intent; 2246c3e380b0SAl Viro 22471f36f774SAl Viro switch (nd->last_type) { 22481f36f774SAl Viro case LAST_DOTDOT: 2249176306f5SNeil Brown case LAST_DOT: 2250fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2251fe2d35ffSAl Viro if (error) 2252fe2d35ffSAl Viro return ERR_PTR(error); 22531f36f774SAl Viro /* fallthrough */ 22541f36f774SAl Viro case LAST_ROOT: 22559f1fafeeSAl Viro error = complete_walk(nd); 225616c2cd71SAl Viro if (error) 22579f1fafeeSAl Viro return ERR_PTR(error); 2258fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2259ca344a89SAl Viro if (open_flag & O_CREAT) { 226016c2cd71SAl Viro error = -EISDIR; 22611f36f774SAl Viro goto exit; 2262fe2d35ffSAl Viro } 2263fe2d35ffSAl Viro goto ok; 22641f36f774SAl Viro case LAST_BIND: 22659f1fafeeSAl Viro error = complete_walk(nd); 226616c2cd71SAl Viro if (error) 22679f1fafeeSAl Viro return ERR_PTR(error); 22681f36f774SAl Viro audit_inode(pathname, dir); 22691f36f774SAl Viro goto ok; 22701f36f774SAl Viro } 2271a2c36b45SAl Viro 2272ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2273bcda7652SAl Viro int symlink_ok = 0; 2274fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2275fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2276bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2277bcda7652SAl Viro symlink_ok = 1; 2278fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2279ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2280ce57dfc1SAl Viro !symlink_ok); 2281ce57dfc1SAl Viro if (error < 0) 2282fe2d35ffSAl Viro return ERR_PTR(error); 2283ce57dfc1SAl Viro if (error) /* symlink */ 2284fe2d35ffSAl Viro return NULL; 2285fe2d35ffSAl Viro /* sayonara */ 22869f1fafeeSAl Viro error = complete_walk(nd); 22879f1fafeeSAl Viro if (error) 22887f6c7e62SMiklos Szeredi return ERR_PTR(error); 2289fe2d35ffSAl Viro 2290fe2d35ffSAl Viro error = -ENOTDIR; 2291fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2292ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2293fe2d35ffSAl Viro goto exit; 2294fe2d35ffSAl Viro } 2295fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2296fe2d35ffSAl Viro goto ok; 2297fe2d35ffSAl Viro } 2298fe2d35ffSAl Viro 2299fe2d35ffSAl Viro /* create side of things */ 2300a3fbbde7SAl Viro /* 2301a3fbbde7SAl Viro * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been 2302a3fbbde7SAl Viro * cleared when we got to the last component we are about to look up 2303a3fbbde7SAl Viro */ 23049f1fafeeSAl Viro error = complete_walk(nd); 23059f1fafeeSAl Viro if (error) 23069f1fafeeSAl Viro return ERR_PTR(error); 2307fe2d35ffSAl Viro 2308fe2d35ffSAl Viro audit_inode(pathname, dir); 230916c2cd71SAl Viro error = -EISDIR; 23101f36f774SAl Viro /* trailing slashes? */ 231131e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 23121f36f774SAl Viro goto exit; 23131f36f774SAl Viro 2314a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2315a1e28038SAl Viro 23166c0d46c4SAl Viro dentry = lookup_hash(nd); 23176c0d46c4SAl Viro error = PTR_ERR(dentry); 23186c0d46c4SAl Viro if (IS_ERR(dentry)) { 2319fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2320fb1cc555SAl Viro goto exit; 2321fb1cc555SAl Viro } 2322fb1cc555SAl Viro 23236c0d46c4SAl Viro path->dentry = dentry; 23246c0d46c4SAl Viro path->mnt = nd->path.mnt; 23256c0d46c4SAl Viro 2326fb1cc555SAl Viro /* Negative dentry, just create the file */ 23276c0d46c4SAl Viro if (!dentry->d_inode) { 2328a218d0fdSAl Viro umode_t mode = op->mode; 23296c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 23306c0d46c4SAl Viro mode &= ~current_umask(); 2331fb1cc555SAl Viro /* 2332fb1cc555SAl Viro * This write is needed to ensure that a 23336c0d46c4SAl Viro * rw->ro transition does not occur between 2334fb1cc555SAl Viro * the time when the file is created and when 2335fb1cc555SAl Viro * a permanent write count is taken through 2336fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2337fb1cc555SAl Viro */ 2338fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2339fb1cc555SAl Viro if (error) 2340fb1cc555SAl Viro goto exit_mutex_unlock; 2341ca344a89SAl Viro want_write = 1; 23429b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2343ca344a89SAl Viro open_flag &= ~O_TRUNC; 23446c0d46c4SAl Viro will_truncate = 0; 2345bcda7652SAl Viro acc_mode = MAY_OPEN; 23466c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 23476c0d46c4SAl Viro if (error) 23486c0d46c4SAl Viro goto exit_mutex_unlock; 23496c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 23506c0d46c4SAl Viro if (error) 23516c0d46c4SAl Viro goto exit_mutex_unlock; 23526c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 23536c0d46c4SAl Viro dput(nd->path.dentry); 23546c0d46c4SAl Viro nd->path.dentry = dentry; 2355ca344a89SAl Viro goto common; 2356fb1cc555SAl Viro } 2357fb1cc555SAl Viro 2358fb1cc555SAl Viro /* 2359fb1cc555SAl Viro * It already exists. 2360fb1cc555SAl Viro */ 2361fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2362fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2363fb1cc555SAl Viro 2364fb1cc555SAl Viro error = -EEXIST; 2365ca344a89SAl Viro if (open_flag & O_EXCL) 2366fb1cc555SAl Viro goto exit_dput; 2367fb1cc555SAl Viro 23689875cf80SDavid Howells error = follow_managed(path, nd->flags); 23699875cf80SDavid Howells if (error < 0) 2370fb1cc555SAl Viro goto exit_dput; 2371fb1cc555SAl Viro 2372a3fbbde7SAl Viro if (error) 2373a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2374a3fbbde7SAl Viro 2375fb1cc555SAl Viro error = -ENOENT; 2376fb1cc555SAl Viro if (!path->dentry->d_inode) 2377fb1cc555SAl Viro goto exit_dput; 23789e67f361SAl Viro 23799e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2380fb1cc555SAl Viro return NULL; 2381fb1cc555SAl Viro 2382fb1cc555SAl Viro path_to_nameidata(path, nd); 238331e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2384a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2385a3fbbde7SAl Viro error = complete_walk(nd); 2386a3fbbde7SAl Viro if (error) 2387097b180cSMiklos Szeredi return ERR_PTR(error); 2388fb1cc555SAl Viro error = -EISDIR; 238931e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2390fb1cc555SAl Viro goto exit; 239167ee3ad2SAl Viro ok: 23926c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 23936c0d46c4SAl Viro will_truncate = 0; 23946c0d46c4SAl Viro 23950f9d1a10SAl Viro if (will_truncate) { 23960f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 23970f9d1a10SAl Viro if (error) 23980f9d1a10SAl Viro goto exit; 2399ca344a89SAl Viro want_write = 1; 24000f9d1a10SAl Viro } 2401ca344a89SAl Viro common: 2402bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2403ca344a89SAl Viro if (error) 24040f9d1a10SAl Viro goto exit; 24050f9d1a10SAl Viro filp = nameidata_to_filp(nd); 24060f9d1a10SAl Viro if (!IS_ERR(filp)) { 24070f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 24080f9d1a10SAl Viro if (error) { 24090f9d1a10SAl Viro fput(filp); 24100f9d1a10SAl Viro filp = ERR_PTR(error); 24110f9d1a10SAl Viro } 24120f9d1a10SAl Viro } 24130f9d1a10SAl Viro if (!IS_ERR(filp)) { 24140f9d1a10SAl Viro if (will_truncate) { 24150f9d1a10SAl Viro error = handle_truncate(filp); 24160f9d1a10SAl Viro if (error) { 24170f9d1a10SAl Viro fput(filp); 24180f9d1a10SAl Viro filp = ERR_PTR(error); 24190f9d1a10SAl Viro } 24200f9d1a10SAl Viro } 24210f9d1a10SAl Viro } 2422ca344a89SAl Viro out: 2423ca344a89SAl Viro if (want_write) 24240f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 24250f9d1a10SAl Viro path_put(&nd->path); 2426fb1cc555SAl Viro return filp; 2427fb1cc555SAl Viro 2428fb1cc555SAl Viro exit_mutex_unlock: 2429fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2430fb1cc555SAl Viro exit_dput: 2431fb1cc555SAl Viro path_put_conditional(path, nd); 2432fb1cc555SAl Viro exit: 2433ca344a89SAl Viro filp = ERR_PTR(error); 2434ca344a89SAl Viro goto out; 2435fb1cc555SAl Viro } 2436fb1cc555SAl Viro 243713aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 243873d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 24391da177e4SLinus Torvalds { 2440fe2d35ffSAl Viro struct file *base = NULL; 24414a3fd211SDave Hansen struct file *filp; 24429850c056SAl Viro struct path path; 244313aab428SAl Viro int error; 244431e6b01fSNick Piggin 244531e6b01fSNick Piggin filp = get_empty_filp(); 244631e6b01fSNick Piggin if (!filp) 244731e6b01fSNick Piggin return ERR_PTR(-ENFILE); 244831e6b01fSNick Piggin 244947c805dcSAl Viro filp->f_flags = op->open_flag; 245073d049a4SAl Viro nd->intent.open.file = filp; 245173d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 245273d049a4SAl Viro nd->intent.open.create_mode = op->mode; 245331e6b01fSNick Piggin 245473d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 245531e6b01fSNick Piggin if (unlikely(error)) 245613aab428SAl Viro goto out_filp; 245731e6b01fSNick Piggin 2458fe2d35ffSAl Viro current->total_link_count = 0; 245973d049a4SAl Viro error = link_path_walk(pathname, nd); 246031e6b01fSNick Piggin if (unlikely(error)) 246131e6b01fSNick Piggin goto out_filp; 24621da177e4SLinus Torvalds 246373d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2464806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 24657b9337aaSNick Piggin struct path link = path; 2466def4af30SAl Viro void *cookie; 2467574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 246873d049a4SAl Viro path_put_conditional(&path, nd); 246973d049a4SAl Viro path_put(&nd->path); 247040b39136SAl Viro filp = ERR_PTR(-ELOOP); 247140b39136SAl Viro break; 247240b39136SAl Viro } 247373d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 247473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2475574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2476c3e380b0SAl Viro if (unlikely(error)) 2477f1afe9efSAl Viro filp = ERR_PTR(error); 2478c3e380b0SAl Viro else 247973d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2480574197e0SAl Viro put_link(nd, &link, cookie); 2481806b681cSAl Viro } 248210fa8e62SAl Viro out: 248373d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 248473d049a4SAl Viro path_put(&nd->root); 2485fe2d35ffSAl Viro if (base) 2486fe2d35ffSAl Viro fput(base); 248773d049a4SAl Viro release_open_intent(nd); 248810fa8e62SAl Viro return filp; 24891da177e4SLinus Torvalds 249031e6b01fSNick Piggin out_filp: 249110fa8e62SAl Viro filp = ERR_PTR(error); 249210fa8e62SAl Viro goto out; 2493de459215SKirill Korotaev } 24941da177e4SLinus Torvalds 249513aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 249613aab428SAl Viro const struct open_flags *op, int flags) 249713aab428SAl Viro { 249873d049a4SAl Viro struct nameidata nd; 249913aab428SAl Viro struct file *filp; 250013aab428SAl Viro 250173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 250213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 250373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 250413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 250573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 250613aab428SAl Viro return filp; 250713aab428SAl Viro } 250813aab428SAl Viro 250973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 251073d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 251173d049a4SAl Viro { 251273d049a4SAl Viro struct nameidata nd; 251373d049a4SAl Viro struct file *file; 251473d049a4SAl Viro 251573d049a4SAl Viro nd.root.mnt = mnt; 251673d049a4SAl Viro nd.root.dentry = dentry; 251773d049a4SAl Viro 251873d049a4SAl Viro flags |= LOOKUP_ROOT; 251973d049a4SAl Viro 2520bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 252173d049a4SAl Viro return ERR_PTR(-ELOOP); 252273d049a4SAl Viro 252373d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 252473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 252573d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 252673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 252773d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 252873d049a4SAl Viro return file; 252973d049a4SAl Viro } 253073d049a4SAl Viro 2531ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 25321da177e4SLinus Torvalds { 2533c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2534ed75e95dSAl Viro struct nameidata nd; 2535ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2536ed75e95dSAl Viro if (error) 2537ed75e95dSAl Viro return ERR_PTR(error); 25381da177e4SLinus Torvalds 2539c663e5d8SChristoph Hellwig /* 2540c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2541c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2542c663e5d8SChristoph Hellwig */ 2543ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2544ed75e95dSAl Viro goto out; 2545ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2546ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2547ed75e95dSAl Viro nd.intent.open.flags = O_EXCL; 2548c663e5d8SChristoph Hellwig 2549c663e5d8SChristoph Hellwig /* 2550c663e5d8SChristoph Hellwig * Do the final lookup. 2551c663e5d8SChristoph Hellwig */ 2552ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2553ed75e95dSAl Viro dentry = lookup_hash(&nd); 25541da177e4SLinus Torvalds if (IS_ERR(dentry)) 25551da177e4SLinus Torvalds goto fail; 2556c663e5d8SChristoph Hellwig 2557e9baf6e5SAl Viro if (dentry->d_inode) 2558e9baf6e5SAl Viro goto eexist; 2559c663e5d8SChristoph Hellwig /* 2560c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2561c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2562c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2563c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2564c663e5d8SChristoph Hellwig */ 2565ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 25661da177e4SLinus Torvalds dput(dentry); 25671da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2568ed75e95dSAl Viro goto fail; 2569e9baf6e5SAl Viro } 2570ed75e95dSAl Viro *path = nd.path; 2571e9baf6e5SAl Viro return dentry; 2572e9baf6e5SAl Viro eexist: 2573e9baf6e5SAl Viro dput(dentry); 2574e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 25751da177e4SLinus Torvalds fail: 2576dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2577ed75e95dSAl Viro out: 2578dae6ad8fSAl Viro path_put(&nd.path); 2579ed75e95dSAl Viro return dentry; 2580dae6ad8fSAl Viro } 2581dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2582dae6ad8fSAl Viro 2583dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2584dae6ad8fSAl Viro { 2585dae6ad8fSAl Viro char *tmp = getname(pathname); 2586dae6ad8fSAl Viro struct dentry *res; 2587dae6ad8fSAl Viro if (IS_ERR(tmp)) 2588dae6ad8fSAl Viro return ERR_CAST(tmp); 2589dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2590dae6ad8fSAl Viro putname(tmp); 2591dae6ad8fSAl Viro return res; 2592dae6ad8fSAl Viro } 2593dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2594dae6ad8fSAl Viro 25951a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 25961da177e4SLinus Torvalds { 2597a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25981da177e4SLinus Torvalds 25991da177e4SLinus Torvalds if (error) 26001da177e4SLinus Torvalds return error; 26011da177e4SLinus Torvalds 2602e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2603e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 26041da177e4SLinus Torvalds return -EPERM; 26051da177e4SLinus Torvalds 2606acfa4380SAl Viro if (!dir->i_op->mknod) 26071da177e4SLinus Torvalds return -EPERM; 26081da177e4SLinus Torvalds 260908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 261008ce5f16SSerge E. Hallyn if (error) 261108ce5f16SSerge E. Hallyn return error; 261208ce5f16SSerge E. Hallyn 26131da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 26141da177e4SLinus Torvalds if (error) 26151da177e4SLinus Torvalds return error; 26161da177e4SLinus Torvalds 26171da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2618a74574aaSStephen Smalley if (!error) 2619f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26201da177e4SLinus Torvalds return error; 26211da177e4SLinus Torvalds } 26221da177e4SLinus Torvalds 2623f69aac00SAl Viro static int may_mknod(umode_t mode) 2624463c3197SDave Hansen { 2625463c3197SDave Hansen switch (mode & S_IFMT) { 2626463c3197SDave Hansen case S_IFREG: 2627463c3197SDave Hansen case S_IFCHR: 2628463c3197SDave Hansen case S_IFBLK: 2629463c3197SDave Hansen case S_IFIFO: 2630463c3197SDave Hansen case S_IFSOCK: 2631463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2632463c3197SDave Hansen return 0; 2633463c3197SDave Hansen case S_IFDIR: 2634463c3197SDave Hansen return -EPERM; 2635463c3197SDave Hansen default: 2636463c3197SDave Hansen return -EINVAL; 2637463c3197SDave Hansen } 2638463c3197SDave Hansen } 2639463c3197SDave Hansen 26408208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 26412e4d0924SHeiko Carstens unsigned, dev) 26421da177e4SLinus Torvalds { 26431da177e4SLinus Torvalds struct dentry *dentry; 2644dae6ad8fSAl Viro struct path path; 2645dae6ad8fSAl Viro int error; 26461da177e4SLinus Torvalds 26471da177e4SLinus Torvalds if (S_ISDIR(mode)) 26481da177e4SLinus Torvalds return -EPERM; 26491da177e4SLinus Torvalds 2650dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2651dae6ad8fSAl Viro if (IS_ERR(dentry)) 2652dae6ad8fSAl Viro return PTR_ERR(dentry); 26532ad94ae6SAl Viro 2654dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2655ce3b0f8dSAl Viro mode &= ~current_umask(); 2656463c3197SDave Hansen error = may_mknod(mode); 2657463c3197SDave Hansen if (error) 2658463c3197SDave Hansen goto out_dput; 2659dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2660463c3197SDave Hansen if (error) 2661463c3197SDave Hansen goto out_dput; 2662dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2663be6d3e56SKentaro Takeda if (error) 2664be6d3e56SKentaro Takeda goto out_drop_write; 26651da177e4SLinus Torvalds switch (mode & S_IFMT) { 26661da177e4SLinus Torvalds case 0: case S_IFREG: 2667dae6ad8fSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); 26681da177e4SLinus Torvalds break; 26691da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2670dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 26711da177e4SLinus Torvalds new_decode_dev(dev)); 26721da177e4SLinus Torvalds break; 26731da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2674dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 26751da177e4SLinus Torvalds break; 26761da177e4SLinus Torvalds } 2677be6d3e56SKentaro Takeda out_drop_write: 2678dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2679463c3197SDave Hansen out_dput: 26801da177e4SLinus Torvalds dput(dentry); 2681dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2682dae6ad8fSAl Viro path_put(&path); 26831da177e4SLinus Torvalds 26841da177e4SLinus Torvalds return error; 26851da177e4SLinus Torvalds } 26861da177e4SLinus Torvalds 26878208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 26885590ff0dSUlrich Drepper { 26895590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 26905590ff0dSUlrich Drepper } 26915590ff0dSUlrich Drepper 269218bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 26931da177e4SLinus Torvalds { 2694a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26958de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 26961da177e4SLinus Torvalds 26971da177e4SLinus Torvalds if (error) 26981da177e4SLinus Torvalds return error; 26991da177e4SLinus Torvalds 2700acfa4380SAl Viro if (!dir->i_op->mkdir) 27011da177e4SLinus Torvalds return -EPERM; 27021da177e4SLinus Torvalds 27031da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 27041da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 27051da177e4SLinus Torvalds if (error) 27061da177e4SLinus Torvalds return error; 27071da177e4SLinus Torvalds 27088de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 27098de52778SAl Viro return -EMLINK; 27108de52778SAl Viro 27111da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2712a74574aaSStephen Smalley if (!error) 2713f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 27141da177e4SLinus Torvalds return error; 27151da177e4SLinus Torvalds } 27161da177e4SLinus Torvalds 2717a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 27181da177e4SLinus Torvalds { 27196902d925SDave Hansen struct dentry *dentry; 2720dae6ad8fSAl Viro struct path path; 2721dae6ad8fSAl Viro int error; 27221da177e4SLinus Torvalds 2723dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 27246902d925SDave Hansen if (IS_ERR(dentry)) 2725dae6ad8fSAl Viro return PTR_ERR(dentry); 27266902d925SDave Hansen 2727dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2728ce3b0f8dSAl Viro mode &= ~current_umask(); 2729dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2730463c3197SDave Hansen if (error) 2731463c3197SDave Hansen goto out_dput; 2732dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 2733be6d3e56SKentaro Takeda if (error) 2734be6d3e56SKentaro Takeda goto out_drop_write; 2735dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 2736be6d3e56SKentaro Takeda out_drop_write: 2737dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2738463c3197SDave Hansen out_dput: 27391da177e4SLinus Torvalds dput(dentry); 2740dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2741dae6ad8fSAl Viro path_put(&path); 27421da177e4SLinus Torvalds return error; 27431da177e4SLinus Torvalds } 27441da177e4SLinus Torvalds 2745a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 27465590ff0dSUlrich Drepper { 27475590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 27485590ff0dSUlrich Drepper } 27495590ff0dSUlrich Drepper 27501da177e4SLinus Torvalds /* 2751a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2752a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2753a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2754a71905f0SSage Weil * then we drop the dentry now. 27551da177e4SLinus Torvalds * 27561da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 27571da177e4SLinus Torvalds * do a 27581da177e4SLinus Torvalds * 27591da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 27601da177e4SLinus Torvalds * return -EBUSY; 27611da177e4SLinus Torvalds * 27621da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 27631da177e4SLinus Torvalds * that is still in use by something else.. 27641da177e4SLinus Torvalds */ 27651da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 27661da177e4SLinus Torvalds { 27671da177e4SLinus Torvalds shrink_dcache_parent(dentry); 27681da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 276964252c75SSage Weil if (dentry->d_count == 1) 27701da177e4SLinus Torvalds __d_drop(dentry); 27711da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 27721da177e4SLinus Torvalds } 27731da177e4SLinus Torvalds 27741da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 27751da177e4SLinus Torvalds { 27761da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 27771da177e4SLinus Torvalds 27781da177e4SLinus Torvalds if (error) 27791da177e4SLinus Torvalds return error; 27801da177e4SLinus Torvalds 2781acfa4380SAl Viro if (!dir->i_op->rmdir) 27821da177e4SLinus Torvalds return -EPERM; 27831da177e4SLinus Torvalds 27841d2ef590SAl Viro dget(dentry); 27851b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2786912dbc15SSage Weil 27871da177e4SLinus Torvalds error = -EBUSY; 2788912dbc15SSage Weil if (d_mountpoint(dentry)) 2789912dbc15SSage Weil goto out; 2790912dbc15SSage Weil 27911da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2792912dbc15SSage Weil if (error) 2793912dbc15SSage Weil goto out; 2794912dbc15SSage Weil 27953cebde24SSage Weil shrink_dcache_parent(dentry); 27961da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2797912dbc15SSage Weil if (error) 2798912dbc15SSage Weil goto out; 2799912dbc15SSage Weil 28001da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2801d83c49f3SAl Viro dont_mount(dentry); 28021da177e4SLinus Torvalds 2803912dbc15SSage Weil out: 2804912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 28051d2ef590SAl Viro dput(dentry); 2806912dbc15SSage Weil if (!error) 2807912dbc15SSage Weil d_delete(dentry); 28081da177e4SLinus Torvalds return error; 28091da177e4SLinus Torvalds } 28101da177e4SLinus Torvalds 28115590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 28121da177e4SLinus Torvalds { 28131da177e4SLinus Torvalds int error = 0; 28141da177e4SLinus Torvalds char * name; 28151da177e4SLinus Torvalds struct dentry *dentry; 28161da177e4SLinus Torvalds struct nameidata nd; 28171da177e4SLinus Torvalds 28182ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 28191da177e4SLinus Torvalds if (error) 28202ad94ae6SAl Viro return error; 28211da177e4SLinus Torvalds 28221da177e4SLinus Torvalds switch(nd.last_type) { 28231da177e4SLinus Torvalds case LAST_DOTDOT: 28241da177e4SLinus Torvalds error = -ENOTEMPTY; 28251da177e4SLinus Torvalds goto exit1; 28261da177e4SLinus Torvalds case LAST_DOT: 28271da177e4SLinus Torvalds error = -EINVAL; 28281da177e4SLinus Torvalds goto exit1; 28291da177e4SLinus Torvalds case LAST_ROOT: 28301da177e4SLinus Torvalds error = -EBUSY; 28311da177e4SLinus Torvalds goto exit1; 28321da177e4SLinus Torvalds } 28330612d9fbSOGAWA Hirofumi 28340612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 28350612d9fbSOGAWA Hirofumi 28364ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 283749705b77SChristoph Hellwig dentry = lookup_hash(&nd); 28381da177e4SLinus Torvalds error = PTR_ERR(dentry); 28396902d925SDave Hansen if (IS_ERR(dentry)) 28406902d925SDave Hansen goto exit2; 2841e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2842e6bc45d6STheodore Ts'o error = -ENOENT; 2843e6bc45d6STheodore Ts'o goto exit3; 2844e6bc45d6STheodore Ts'o } 28450622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 28460622753bSDave Hansen if (error) 28470622753bSDave Hansen goto exit3; 2848be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2849be6d3e56SKentaro Takeda if (error) 2850be6d3e56SKentaro Takeda goto exit4; 28514ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2852be6d3e56SKentaro Takeda exit4: 28530622753bSDave Hansen mnt_drop_write(nd.path.mnt); 28540622753bSDave Hansen exit3: 28551da177e4SLinus Torvalds dput(dentry); 28566902d925SDave Hansen exit2: 28574ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28581da177e4SLinus Torvalds exit1: 28591d957f9bSJan Blunck path_put(&nd.path); 28601da177e4SLinus Torvalds putname(name); 28611da177e4SLinus Torvalds return error; 28621da177e4SLinus Torvalds } 28631da177e4SLinus Torvalds 28643cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 28655590ff0dSUlrich Drepper { 28665590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 28675590ff0dSUlrich Drepper } 28685590ff0dSUlrich Drepper 28691da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 28701da177e4SLinus Torvalds { 28711da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 28721da177e4SLinus Torvalds 28731da177e4SLinus Torvalds if (error) 28741da177e4SLinus Torvalds return error; 28751da177e4SLinus Torvalds 2876acfa4380SAl Viro if (!dir->i_op->unlink) 28771da177e4SLinus Torvalds return -EPERM; 28781da177e4SLinus Torvalds 28791b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 28801da177e4SLinus Torvalds if (d_mountpoint(dentry)) 28811da177e4SLinus Torvalds error = -EBUSY; 28821da177e4SLinus Torvalds else { 28831da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2884bec1052eSAl Viro if (!error) { 28851da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2886bec1052eSAl Viro if (!error) 2887d83c49f3SAl Viro dont_mount(dentry); 2888bec1052eSAl Viro } 28891da177e4SLinus Torvalds } 28901b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 28911da177e4SLinus Torvalds 28921da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 28931da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2894ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 28951da177e4SLinus Torvalds d_delete(dentry); 28961da177e4SLinus Torvalds } 28970eeca283SRobert Love 28981da177e4SLinus Torvalds return error; 28991da177e4SLinus Torvalds } 29001da177e4SLinus Torvalds 29011da177e4SLinus Torvalds /* 29021da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 29031b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 29041da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 29051da177e4SLinus Torvalds * while waiting on the I/O. 29061da177e4SLinus Torvalds */ 29075590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 29081da177e4SLinus Torvalds { 29092ad94ae6SAl Viro int error; 29101da177e4SLinus Torvalds char *name; 29111da177e4SLinus Torvalds struct dentry *dentry; 29121da177e4SLinus Torvalds struct nameidata nd; 29131da177e4SLinus Torvalds struct inode *inode = NULL; 29141da177e4SLinus Torvalds 29152ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 29161da177e4SLinus Torvalds if (error) 29172ad94ae6SAl Viro return error; 29182ad94ae6SAl Viro 29191da177e4SLinus Torvalds error = -EISDIR; 29201da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 29211da177e4SLinus Torvalds goto exit1; 29220612d9fbSOGAWA Hirofumi 29230612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 29240612d9fbSOGAWA Hirofumi 29254ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 292649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 29271da177e4SLinus Torvalds error = PTR_ERR(dentry); 29281da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 29291da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 293050338b88STörök Edwin if (nd.last.name[nd.last.len]) 293150338b88STörök Edwin goto slashes; 29321da177e4SLinus Torvalds inode = dentry->d_inode; 293350338b88STörök Edwin if (!inode) 2934e6bc45d6STheodore Ts'o goto slashes; 29357de9c6eeSAl Viro ihold(inode); 29360622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 29370622753bSDave Hansen if (error) 29380622753bSDave Hansen goto exit2; 2939be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2940be6d3e56SKentaro Takeda if (error) 2941be6d3e56SKentaro Takeda goto exit3; 29424ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2943be6d3e56SKentaro Takeda exit3: 29440622753bSDave Hansen mnt_drop_write(nd.path.mnt); 29451da177e4SLinus Torvalds exit2: 29461da177e4SLinus Torvalds dput(dentry); 29471da177e4SLinus Torvalds } 29484ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29491da177e4SLinus Torvalds if (inode) 29501da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 29511da177e4SLinus Torvalds exit1: 29521d957f9bSJan Blunck path_put(&nd.path); 29531da177e4SLinus Torvalds putname(name); 29541da177e4SLinus Torvalds return error; 29551da177e4SLinus Torvalds 29561da177e4SLinus Torvalds slashes: 29571da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 29581da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 29591da177e4SLinus Torvalds goto exit2; 29601da177e4SLinus Torvalds } 29611da177e4SLinus Torvalds 29622e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 29635590ff0dSUlrich Drepper { 29645590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 29655590ff0dSUlrich Drepper return -EINVAL; 29665590ff0dSUlrich Drepper 29675590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 29685590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 29695590ff0dSUlrich Drepper 29705590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 29715590ff0dSUlrich Drepper } 29725590ff0dSUlrich Drepper 29733480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 29745590ff0dSUlrich Drepper { 29755590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 29765590ff0dSUlrich Drepper } 29775590ff0dSUlrich Drepper 2978db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 29791da177e4SLinus Torvalds { 2980a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 29811da177e4SLinus Torvalds 29821da177e4SLinus Torvalds if (error) 29831da177e4SLinus Torvalds return error; 29841da177e4SLinus Torvalds 2985acfa4380SAl Viro if (!dir->i_op->symlink) 29861da177e4SLinus Torvalds return -EPERM; 29871da177e4SLinus Torvalds 29881da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 29891da177e4SLinus Torvalds if (error) 29901da177e4SLinus Torvalds return error; 29911da177e4SLinus Torvalds 29921da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2993a74574aaSStephen Smalley if (!error) 2994f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29951da177e4SLinus Torvalds return error; 29961da177e4SLinus Torvalds } 29971da177e4SLinus Torvalds 29982e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 29992e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 30001da177e4SLinus Torvalds { 30012ad94ae6SAl Viro int error; 30021da177e4SLinus Torvalds char *from; 30036902d925SDave Hansen struct dentry *dentry; 3004dae6ad8fSAl Viro struct path path; 30051da177e4SLinus Torvalds 30061da177e4SLinus Torvalds from = getname(oldname); 30071da177e4SLinus Torvalds if (IS_ERR(from)) 30081da177e4SLinus Torvalds return PTR_ERR(from); 30092ad94ae6SAl Viro 3010dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 30111da177e4SLinus Torvalds error = PTR_ERR(dentry); 30126902d925SDave Hansen if (IS_ERR(dentry)) 3013dae6ad8fSAl Viro goto out_putname; 30146902d925SDave Hansen 3015dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 301675c3f29dSDave Hansen if (error) 301775c3f29dSDave Hansen goto out_dput; 3018dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 3019be6d3e56SKentaro Takeda if (error) 3020be6d3e56SKentaro Takeda goto out_drop_write; 3021dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 3022be6d3e56SKentaro Takeda out_drop_write: 3023dae6ad8fSAl Viro mnt_drop_write(path.mnt); 302475c3f29dSDave Hansen out_dput: 30251da177e4SLinus Torvalds dput(dentry); 3026dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3027dae6ad8fSAl Viro path_put(&path); 30286902d925SDave Hansen out_putname: 30291da177e4SLinus Torvalds putname(from); 30301da177e4SLinus Torvalds return error; 30311da177e4SLinus Torvalds } 30321da177e4SLinus Torvalds 30333480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 30345590ff0dSUlrich Drepper { 30355590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 30365590ff0dSUlrich Drepper } 30375590ff0dSUlrich Drepper 30381da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 30391da177e4SLinus Torvalds { 30401da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 30418de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 30421da177e4SLinus Torvalds int error; 30431da177e4SLinus Torvalds 30441da177e4SLinus Torvalds if (!inode) 30451da177e4SLinus Torvalds return -ENOENT; 30461da177e4SLinus Torvalds 3047a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 30481da177e4SLinus Torvalds if (error) 30491da177e4SLinus Torvalds return error; 30501da177e4SLinus Torvalds 30511da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 30521da177e4SLinus Torvalds return -EXDEV; 30531da177e4SLinus Torvalds 30541da177e4SLinus Torvalds /* 30551da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 30561da177e4SLinus Torvalds */ 30571da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 30581da177e4SLinus Torvalds return -EPERM; 3059acfa4380SAl Viro if (!dir->i_op->link) 30601da177e4SLinus Torvalds return -EPERM; 30617e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 30621da177e4SLinus Torvalds return -EPERM; 30631da177e4SLinus Torvalds 30641da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 30651da177e4SLinus Torvalds if (error) 30661da177e4SLinus Torvalds return error; 30671da177e4SLinus Torvalds 30687e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3069aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3070aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3071aae8a97dSAneesh Kumar K.V error = -ENOENT; 30728de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 30738de52778SAl Viro error = -EMLINK; 3074aae8a97dSAneesh Kumar K.V else 30751da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 30767e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3077e31e14ecSStephen Smalley if (!error) 30787e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 30791da177e4SLinus Torvalds return error; 30801da177e4SLinus Torvalds } 30811da177e4SLinus Torvalds 30821da177e4SLinus Torvalds /* 30831da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 30841da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 30851da177e4SLinus Torvalds * newname. --KAB 30861da177e4SLinus Torvalds * 30871da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 30881da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 30891da177e4SLinus Torvalds * and other special files. --ADM 30901da177e4SLinus Torvalds */ 30912e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 30922e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 30931da177e4SLinus Torvalds { 30941da177e4SLinus Torvalds struct dentry *new_dentry; 3095dae6ad8fSAl Viro struct path old_path, new_path; 309611a7b371SAneesh Kumar K.V int how = 0; 30971da177e4SLinus Torvalds int error; 30981da177e4SLinus Torvalds 309911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3100c04030e1SUlrich Drepper return -EINVAL; 310111a7b371SAneesh Kumar K.V /* 310211a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 310311a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 310411a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 310511a7b371SAneesh Kumar K.V */ 310611a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 310711a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 310811a7b371SAneesh Kumar K.V return -ENOENT; 310911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 311011a7b371SAneesh Kumar K.V } 3111c04030e1SUlrich Drepper 311211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 311311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 311411a7b371SAneesh Kumar K.V 311511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 31161da177e4SLinus Torvalds if (error) 31172ad94ae6SAl Viro return error; 31182ad94ae6SAl Viro 3119dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 31201da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31216902d925SDave Hansen if (IS_ERR(new_dentry)) 3122dae6ad8fSAl Viro goto out; 3123dae6ad8fSAl Viro 3124dae6ad8fSAl Viro error = -EXDEV; 3125dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3126dae6ad8fSAl Viro goto out_dput; 3127dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 312875c3f29dSDave Hansen if (error) 312975c3f29dSDave Hansen goto out_dput; 3130dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3131be6d3e56SKentaro Takeda if (error) 3132be6d3e56SKentaro Takeda goto out_drop_write; 3133dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 3134be6d3e56SKentaro Takeda out_drop_write: 3135dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 313675c3f29dSDave Hansen out_dput: 31371da177e4SLinus Torvalds dput(new_dentry); 3138dae6ad8fSAl Viro mutex_unlock(&new_path.dentry->d_inode->i_mutex); 3139dae6ad8fSAl Viro path_put(&new_path); 31401da177e4SLinus Torvalds out: 31412d8f3038SAl Viro path_put(&old_path); 31421da177e4SLinus Torvalds 31431da177e4SLinus Torvalds return error; 31441da177e4SLinus Torvalds } 31451da177e4SLinus Torvalds 31463480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 31475590ff0dSUlrich Drepper { 3148c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 31495590ff0dSUlrich Drepper } 31505590ff0dSUlrich Drepper 31511da177e4SLinus Torvalds /* 31521da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 31531da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 31541da177e4SLinus Torvalds * Problems: 31551da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 31561da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 31571da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3158a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 31591da177e4SLinus Torvalds * story. 31601da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 31611b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 31621da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 31631da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3164a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 31651da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 31661da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 31671da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3168a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 31691da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 31701da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 31711da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3172e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 31731b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 31741da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3175c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 31761da177e4SLinus Torvalds * locking]. 31771da177e4SLinus Torvalds */ 317875c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 31791da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31801da177e4SLinus Torvalds { 31811da177e4SLinus Torvalds int error = 0; 31829055cba7SSage Weil struct inode *target = new_dentry->d_inode; 31838de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 31841da177e4SLinus Torvalds 31851da177e4SLinus Torvalds /* 31861da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 31871da177e4SLinus Torvalds * we'll need to flip '..'. 31881da177e4SLinus Torvalds */ 31891da177e4SLinus Torvalds if (new_dir != old_dir) { 3190f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 31911da177e4SLinus Torvalds if (error) 31921da177e4SLinus Torvalds return error; 31931da177e4SLinus Torvalds } 31941da177e4SLinus Torvalds 31951da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 31961da177e4SLinus Torvalds if (error) 31971da177e4SLinus Torvalds return error; 31981da177e4SLinus Torvalds 31991d2ef590SAl Viro dget(new_dentry); 3200d83c49f3SAl Viro if (target) 32011b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 32029055cba7SSage Weil 32031da177e4SLinus Torvalds error = -EBUSY; 32049055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 32059055cba7SSage Weil goto out; 32069055cba7SSage Weil 32078de52778SAl Viro error = -EMLINK; 32088de52778SAl Viro if (max_links && !target && new_dir != old_dir && 32098de52778SAl Viro new_dir->i_nlink >= max_links) 32108de52778SAl Viro goto out; 32118de52778SAl Viro 32123cebde24SSage Weil if (target) 32133cebde24SSage Weil shrink_dcache_parent(new_dentry); 32141da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 32159055cba7SSage Weil if (error) 32169055cba7SSage Weil goto out; 32179055cba7SSage Weil 32181da177e4SLinus Torvalds if (target) { 32191da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3220d83c49f3SAl Viro dont_mount(new_dentry); 3221d83c49f3SAl Viro } 32229055cba7SSage Weil out: 32239055cba7SSage Weil if (target) 32241b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 32251d2ef590SAl Viro dput(new_dentry); 3226e31e14ecSStephen Smalley if (!error) 3227349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 32281da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 32291da177e4SLinus Torvalds return error; 32301da177e4SLinus Torvalds } 32311da177e4SLinus Torvalds 323275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 32331da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32341da177e4SLinus Torvalds { 323551892bbbSSage Weil struct inode *target = new_dentry->d_inode; 32361da177e4SLinus Torvalds int error; 32371da177e4SLinus Torvalds 32381da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 32391da177e4SLinus Torvalds if (error) 32401da177e4SLinus Torvalds return error; 32411da177e4SLinus Torvalds 32421da177e4SLinus Torvalds dget(new_dentry); 32431da177e4SLinus Torvalds if (target) 32441b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 324551892bbbSSage Weil 32461da177e4SLinus Torvalds error = -EBUSY; 324751892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 324851892bbbSSage Weil goto out; 324951892bbbSSage Weil 32501da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 325151892bbbSSage Weil if (error) 325251892bbbSSage Weil goto out; 325351892bbbSSage Weil 3254bec1052eSAl Viro if (target) 3255d83c49f3SAl Viro dont_mount(new_dentry); 3256349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 32571da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 325851892bbbSSage Weil out: 32591da177e4SLinus Torvalds if (target) 32601b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 32611da177e4SLinus Torvalds dput(new_dentry); 32621da177e4SLinus Torvalds return error; 32631da177e4SLinus Torvalds } 32641da177e4SLinus Torvalds 32651da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 32661da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32671da177e4SLinus Torvalds { 32681da177e4SLinus Torvalds int error; 32691da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 327059b0df21SEric Paris const unsigned char *old_name; 32711da177e4SLinus Torvalds 32721da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 32731da177e4SLinus Torvalds return 0; 32741da177e4SLinus Torvalds 32751da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 32761da177e4SLinus Torvalds if (error) 32771da177e4SLinus Torvalds return error; 32781da177e4SLinus Torvalds 32791da177e4SLinus Torvalds if (!new_dentry->d_inode) 3280a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 32811da177e4SLinus Torvalds else 32821da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 32831da177e4SLinus Torvalds if (error) 32841da177e4SLinus Torvalds return error; 32851da177e4SLinus Torvalds 3286acfa4380SAl Viro if (!old_dir->i_op->rename) 32871da177e4SLinus Torvalds return -EPERM; 32881da177e4SLinus Torvalds 32890eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 32900eeca283SRobert Love 32911da177e4SLinus Torvalds if (is_dir) 32921da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 32931da177e4SLinus Torvalds else 32941da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3295123df294SAl Viro if (!error) 3296123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 32975a190ae6SAl Viro new_dentry->d_inode, old_dentry); 32980eeca283SRobert Love fsnotify_oldname_free(old_name); 32990eeca283SRobert Love 33001da177e4SLinus Torvalds return error; 33011da177e4SLinus Torvalds } 33021da177e4SLinus Torvalds 33032e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 33042e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 33051da177e4SLinus Torvalds { 33061da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 33071da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 33081da177e4SLinus Torvalds struct dentry *trap; 33091da177e4SLinus Torvalds struct nameidata oldnd, newnd; 33102ad94ae6SAl Viro char *from; 33112ad94ae6SAl Viro char *to; 33122ad94ae6SAl Viro int error; 33131da177e4SLinus Torvalds 33142ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 33151da177e4SLinus Torvalds if (error) 33161da177e4SLinus Torvalds goto exit; 33171da177e4SLinus Torvalds 33182ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 33191da177e4SLinus Torvalds if (error) 33201da177e4SLinus Torvalds goto exit1; 33211da177e4SLinus Torvalds 33221da177e4SLinus Torvalds error = -EXDEV; 33234ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 33241da177e4SLinus Torvalds goto exit2; 33251da177e4SLinus Torvalds 33264ac91378SJan Blunck old_dir = oldnd.path.dentry; 33271da177e4SLinus Torvalds error = -EBUSY; 33281da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 33291da177e4SLinus Torvalds goto exit2; 33301da177e4SLinus Torvalds 33314ac91378SJan Blunck new_dir = newnd.path.dentry; 33321da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 33331da177e4SLinus Torvalds goto exit2; 33341da177e4SLinus Torvalds 33350612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 33360612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 33374e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 33380612d9fbSOGAWA Hirofumi 33391da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 33401da177e4SLinus Torvalds 334149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 33421da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 33431da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 33441da177e4SLinus Torvalds goto exit3; 33451da177e4SLinus Torvalds /* source must exist */ 33461da177e4SLinus Torvalds error = -ENOENT; 33471da177e4SLinus Torvalds if (!old_dentry->d_inode) 33481da177e4SLinus Torvalds goto exit4; 33491da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 33501da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 33511da177e4SLinus Torvalds error = -ENOTDIR; 33521da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 33531da177e4SLinus Torvalds goto exit4; 33541da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 33551da177e4SLinus Torvalds goto exit4; 33561da177e4SLinus Torvalds } 33571da177e4SLinus Torvalds /* source should not be ancestor of target */ 33581da177e4SLinus Torvalds error = -EINVAL; 33591da177e4SLinus Torvalds if (old_dentry == trap) 33601da177e4SLinus Torvalds goto exit4; 336149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 33621da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 33631da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 33641da177e4SLinus Torvalds goto exit4; 33651da177e4SLinus Torvalds /* target should not be an ancestor of source */ 33661da177e4SLinus Torvalds error = -ENOTEMPTY; 33671da177e4SLinus Torvalds if (new_dentry == trap) 33681da177e4SLinus Torvalds goto exit5; 33691da177e4SLinus Torvalds 33709079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 33719079b1ebSDave Hansen if (error) 33729079b1ebSDave Hansen goto exit5; 3373be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3374be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3375be6d3e56SKentaro Takeda if (error) 3376be6d3e56SKentaro Takeda goto exit6; 33771da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 33781da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3379be6d3e56SKentaro Takeda exit6: 33809079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 33811da177e4SLinus Torvalds exit5: 33821da177e4SLinus Torvalds dput(new_dentry); 33831da177e4SLinus Torvalds exit4: 33841da177e4SLinus Torvalds dput(old_dentry); 33851da177e4SLinus Torvalds exit3: 33861da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 33871da177e4SLinus Torvalds exit2: 33881d957f9bSJan Blunck path_put(&newnd.path); 33892ad94ae6SAl Viro putname(to); 33901da177e4SLinus Torvalds exit1: 33911d957f9bSJan Blunck path_put(&oldnd.path); 33921da177e4SLinus Torvalds putname(from); 33932ad94ae6SAl Viro exit: 33941da177e4SLinus Torvalds return error; 33951da177e4SLinus Torvalds } 33961da177e4SLinus Torvalds 3397a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 33985590ff0dSUlrich Drepper { 33995590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 34005590ff0dSUlrich Drepper } 34015590ff0dSUlrich Drepper 34021da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 34031da177e4SLinus Torvalds { 34041da177e4SLinus Torvalds int len; 34051da177e4SLinus Torvalds 34061da177e4SLinus Torvalds len = PTR_ERR(link); 34071da177e4SLinus Torvalds if (IS_ERR(link)) 34081da177e4SLinus Torvalds goto out; 34091da177e4SLinus Torvalds 34101da177e4SLinus Torvalds len = strlen(link); 34111da177e4SLinus Torvalds if (len > (unsigned) buflen) 34121da177e4SLinus Torvalds len = buflen; 34131da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 34141da177e4SLinus Torvalds len = -EFAULT; 34151da177e4SLinus Torvalds out: 34161da177e4SLinus Torvalds return len; 34171da177e4SLinus Torvalds } 34181da177e4SLinus Torvalds 34191da177e4SLinus Torvalds /* 34201da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 34211da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 34221da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 34231da177e4SLinus Torvalds */ 34241da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 34251da177e4SLinus Torvalds { 34261da177e4SLinus Torvalds struct nameidata nd; 3427cc314eefSLinus Torvalds void *cookie; 3428694a1764SMarcin Slusarz int res; 3429cc314eefSLinus Torvalds 34301da177e4SLinus Torvalds nd.depth = 0; 3431cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3432694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3433694a1764SMarcin Slusarz return PTR_ERR(cookie); 3434694a1764SMarcin Slusarz 3435694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 34361da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3437cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3438694a1764SMarcin Slusarz return res; 34391da177e4SLinus Torvalds } 34401da177e4SLinus Torvalds 34411da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 34421da177e4SLinus Torvalds { 34431da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 34441da177e4SLinus Torvalds } 34451da177e4SLinus Torvalds 34461da177e4SLinus Torvalds /* get the link contents into pagecache */ 34471da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 34481da177e4SLinus Torvalds { 3449ebd09abbSDuane Griffin char *kaddr; 34501da177e4SLinus Torvalds struct page *page; 34511da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3452090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 34531da177e4SLinus Torvalds if (IS_ERR(page)) 34546fe6900eSNick Piggin return (char*)page; 34551da177e4SLinus Torvalds *ppage = page; 3456ebd09abbSDuane Griffin kaddr = kmap(page); 3457ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3458ebd09abbSDuane Griffin return kaddr; 34591da177e4SLinus Torvalds } 34601da177e4SLinus Torvalds 34611da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 34621da177e4SLinus Torvalds { 34631da177e4SLinus Torvalds struct page *page = NULL; 34641da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 34651da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 34661da177e4SLinus Torvalds if (page) { 34671da177e4SLinus Torvalds kunmap(page); 34681da177e4SLinus Torvalds page_cache_release(page); 34691da177e4SLinus Torvalds } 34701da177e4SLinus Torvalds return res; 34711da177e4SLinus Torvalds } 34721da177e4SLinus Torvalds 3473cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 34741da177e4SLinus Torvalds { 3475cc314eefSLinus Torvalds struct page *page = NULL; 34761da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3477cc314eefSLinus Torvalds return page; 34781da177e4SLinus Torvalds } 34791da177e4SLinus Torvalds 3480cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 34811da177e4SLinus Torvalds { 3482cc314eefSLinus Torvalds struct page *page = cookie; 3483cc314eefSLinus Torvalds 3484cc314eefSLinus Torvalds if (page) { 34851da177e4SLinus Torvalds kunmap(page); 34861da177e4SLinus Torvalds page_cache_release(page); 34871da177e4SLinus Torvalds } 34881da177e4SLinus Torvalds } 34891da177e4SLinus Torvalds 349054566b2cSNick Piggin /* 349154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 349254566b2cSNick Piggin */ 349354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 34941da177e4SLinus Torvalds { 34951da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 34960adb25d2SKirill Korotaev struct page *page; 3497afddba49SNick Piggin void *fsdata; 3498beb497abSDmitriy Monakhov int err; 34991da177e4SLinus Torvalds char *kaddr; 350054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 350154566b2cSNick Piggin if (nofs) 350254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 35031da177e4SLinus Torvalds 35047e53cac4SNeilBrown retry: 3505afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 350654566b2cSNick Piggin flags, &page, &fsdata); 35071da177e4SLinus Torvalds if (err) 3508afddba49SNick Piggin goto fail; 3509afddba49SNick Piggin 3510e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 35111da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3512e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3513afddba49SNick Piggin 3514afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3515afddba49SNick Piggin page, fsdata); 35161da177e4SLinus Torvalds if (err < 0) 35171da177e4SLinus Torvalds goto fail; 3518afddba49SNick Piggin if (err < len-1) 3519afddba49SNick Piggin goto retry; 3520afddba49SNick Piggin 35211da177e4SLinus Torvalds mark_inode_dirty(inode); 35221da177e4SLinus Torvalds return 0; 35231da177e4SLinus Torvalds fail: 35241da177e4SLinus Torvalds return err; 35251da177e4SLinus Torvalds } 35261da177e4SLinus Torvalds 35270adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 35280adb25d2SKirill Korotaev { 35290adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 353054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 35310adb25d2SKirill Korotaev } 35320adb25d2SKirill Korotaev 353392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 35341da177e4SLinus Torvalds .readlink = generic_readlink, 35351da177e4SLinus Torvalds .follow_link = page_follow_link_light, 35361da177e4SLinus Torvalds .put_link = page_put_link, 35371da177e4SLinus Torvalds }; 35381da177e4SLinus Torvalds 35392d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3540cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 35411da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 35421da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 35431da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 35441da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 35451da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 35461da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 35471da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 35481da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 35491da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 35500adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 35511da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 35521da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3553d1811465SAl Viro EXPORT_SYMBOL(kern_path); 355416f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3555f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 35561da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 35571da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 35581da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 35591da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 35601da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 35611da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 35621da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 35631da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 35641da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 35651da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 35661da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 35671da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 35681da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 35691da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3570