11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 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 /* 1057bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1058bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1059bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1060bad61189SMiklos Szeredi * 1061bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1062baa03890SNick Piggin */ 1063bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1064bad61189SMiklos Szeredi struct nameidata *nd, bool *need_lookup) 1065baa03890SNick Piggin { 1066baa03890SNick Piggin struct dentry *dentry; 1067bad61189SMiklos Szeredi int error; 1068baa03890SNick Piggin 1069bad61189SMiklos Szeredi *need_lookup = false; 1070bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1071bad61189SMiklos Szeredi if (dentry) { 1072bad61189SMiklos Szeredi if (d_need_lookup(dentry)) { 1073bad61189SMiklos Szeredi *need_lookup = true; 1074bad61189SMiklos Szeredi } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1075bad61189SMiklos Szeredi error = d_revalidate(dentry, nd); 1076bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1077bad61189SMiklos Szeredi if (error < 0) { 1078bad61189SMiklos Szeredi dput(dentry); 1079bad61189SMiklos Szeredi return ERR_PTR(error); 1080bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1081bad61189SMiklos Szeredi dput(dentry); 1082bad61189SMiklos Szeredi dentry = NULL; 1083bad61189SMiklos Szeredi } 1084bad61189SMiklos Szeredi } 1085bad61189SMiklos Szeredi } 1086bad61189SMiklos Szeredi } 1087baa03890SNick Piggin 1088bad61189SMiklos Szeredi if (!dentry) { 1089bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1090baa03890SNick Piggin if (unlikely(!dentry)) 1091baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1092baa03890SNick Piggin 1093bad61189SMiklos Szeredi *need_lookup = true; 1094baa03890SNick Piggin } 1095baa03890SNick Piggin return dentry; 1096baa03890SNick Piggin } 1097baa03890SNick Piggin 1098baa03890SNick Piggin /* 1099bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1100bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1101bad61189SMiklos Szeredi * 1102bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 110344396f4bSJosef Bacik */ 1104bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 110544396f4bSJosef Bacik struct nameidata *nd) 110644396f4bSJosef Bacik { 110744396f4bSJosef Bacik struct dentry *old; 110844396f4bSJosef Bacik 110944396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1110bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1111e188dc02SMiklos Szeredi dput(dentry); 111244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1113e188dc02SMiklos Szeredi } 111444396f4bSJosef Bacik 1115bad61189SMiklos Szeredi old = dir->i_op->lookup(dir, dentry, nd); 111644396f4bSJosef Bacik if (unlikely(old)) { 111744396f4bSJosef Bacik dput(dentry); 111844396f4bSJosef Bacik dentry = old; 111944396f4bSJosef Bacik } 112044396f4bSJosef Bacik return dentry; 112144396f4bSJosef Bacik } 112244396f4bSJosef Bacik 1123a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 1124a3255546SAl Viro struct dentry *base, struct nameidata *nd) 1125a3255546SAl Viro { 1126bad61189SMiklos Szeredi bool need_lookup; 1127a3255546SAl Viro struct dentry *dentry; 1128a3255546SAl Viro 1129bad61189SMiklos Szeredi dentry = lookup_dcache(name, base, nd, &need_lookup); 1130bad61189SMiklos Szeredi if (!need_lookup) 1131a3255546SAl Viro return dentry; 1132bad61189SMiklos Szeredi 1133bad61189SMiklos Szeredi return lookup_real(base->d_inode, dentry, nd); 1134a3255546SAl Viro } 1135a3255546SAl Viro 113644396f4bSJosef Bacik /* 11371da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11381da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11391da177e4SLinus Torvalds * It _is_ time-critical. 11401da177e4SLinus Torvalds */ 11411da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 114231e6b01fSNick Piggin struct path *path, struct inode **inode) 11431da177e4SLinus Torvalds { 11444ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 114531e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11465a18fff2SAl Viro int need_reval = 1; 11475a18fff2SAl Viro int status = 1; 11489875cf80SDavid Howells int err; 11499875cf80SDavid Howells 11503cac260aSAl Viro /* 1151b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1152b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1153b04f784eSNick Piggin * do the non-racy lookup, below. 1154b04f784eSNick Piggin */ 115531e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 115631e6b01fSNick Piggin unsigned seq; 115731e6b01fSNick Piggin *inode = nd->inode; 115831e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11595a18fff2SAl Viro if (!dentry) 11605a18fff2SAl Viro goto unlazy; 11615a18fff2SAl Viro 116231e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 116331e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 116431e6b01fSNick Piggin return -ECHILD; 116531e6b01fSNick Piggin nd->seq = seq; 11665a18fff2SAl Viro 1167fa4ee159SMiklos Szeredi if (unlikely(d_need_lookup(dentry))) 1168fa4ee159SMiklos Szeredi goto unlazy; 116924643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11705a18fff2SAl Viro status = d_revalidate(dentry, nd); 11715a18fff2SAl Viro if (unlikely(status <= 0)) { 11725a18fff2SAl Viro if (status != -ECHILD) 11735a18fff2SAl Viro need_reval = 0; 11745a18fff2SAl Viro goto unlazy; 11755a18fff2SAl Viro } 117624643087SAl Viro } 117731e6b01fSNick Piggin path->mnt = mnt; 117831e6b01fSNick Piggin path->dentry = dentry; 1179d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1180d6e9bd25SAl Viro goto unlazy; 1181d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1182d6e9bd25SAl Viro goto unlazy; 11839875cf80SDavid Howells return 0; 11845a18fff2SAl Viro unlazy: 118519660af7SAl Viro if (unlazy_walk(nd, dentry)) 11865a18fff2SAl Viro return -ECHILD; 11875a18fff2SAl Viro } else { 118831e6b01fSNick Piggin dentry = __d_lookup(parent, name); 118924643087SAl Viro } 11905a18fff2SAl Viro 119181e6f520SAl Viro if (unlikely(!dentry)) 119281e6f520SAl Viro goto need_lookup; 11935a18fff2SAl Viro 119481e6f520SAl Viro if (unlikely(d_need_lookup(dentry))) { 119581e6f520SAl Viro dput(dentry); 119681e6f520SAl Viro goto need_lookup; 11975a18fff2SAl Viro } 119881e6f520SAl Viro 11995a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12005a18fff2SAl Viro status = d_revalidate(dentry, nd); 12015a18fff2SAl Viro if (unlikely(status <= 0)) { 12025a18fff2SAl Viro if (status < 0) { 12035a18fff2SAl Viro dput(dentry); 12045a18fff2SAl Viro return status; 12055a18fff2SAl Viro } 12065a18fff2SAl Viro if (!d_invalidate(dentry)) { 12075a18fff2SAl Viro dput(dentry); 120881e6f520SAl Viro goto need_lookup; 12095a18fff2SAl Viro } 12105a18fff2SAl Viro } 12113f6c7c71SAl Viro done: 12121da177e4SLinus Torvalds path->mnt = mnt; 12131da177e4SLinus Torvalds path->dentry = dentry; 12149875cf80SDavid Howells err = follow_managed(path, nd->flags); 121589312214SIan Kent if (unlikely(err < 0)) { 121689312214SIan Kent path_put_conditional(path, nd); 12179875cf80SDavid Howells return err; 121889312214SIan Kent } 1219a3fbbde7SAl Viro if (err) 1220a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 122131e6b01fSNick Piggin *inode = path->dentry->d_inode; 12221da177e4SLinus Torvalds return 0; 122381e6f520SAl Viro 122481e6f520SAl Viro need_lookup: 122581e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 122681e6f520SAl Viro 122781e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 122881e6f520SAl Viro dentry = __lookup_hash(name, parent, nd); 122981e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 123081e6f520SAl Viro if (IS_ERR(dentry)) 123181e6f520SAl Viro return PTR_ERR(dentry); 123281e6f520SAl Viro goto done; 12331da177e4SLinus Torvalds } 12341da177e4SLinus Torvalds 123552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 123652094c8aSAl Viro { 123752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 12384ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 123952094c8aSAl Viro if (err != -ECHILD) 124052094c8aSAl Viro return err; 124119660af7SAl Viro if (unlazy_walk(nd, NULL)) 124252094c8aSAl Viro return -ECHILD; 124352094c8aSAl Viro } 12444ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 124552094c8aSAl Viro } 124652094c8aSAl Viro 12479856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12489856fa1bSAl Viro { 12499856fa1bSAl Viro if (type == LAST_DOTDOT) { 12509856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12519856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12529856fa1bSAl Viro return -ECHILD; 12539856fa1bSAl Viro } else 12549856fa1bSAl Viro follow_dotdot(nd); 12559856fa1bSAl Viro } 12569856fa1bSAl Viro return 0; 12579856fa1bSAl Viro } 12589856fa1bSAl Viro 1259951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1260951361f9SAl Viro { 1261951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1262951361f9SAl Viro path_put(&nd->path); 1263951361f9SAl Viro } else { 1264951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12655b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1266951361f9SAl Viro nd->root.mnt = NULL; 1267951361f9SAl Viro rcu_read_unlock(); 1268951361f9SAl Viro br_read_unlock(vfsmount_lock); 1269951361f9SAl Viro } 1270951361f9SAl Viro } 1271951361f9SAl Viro 12723ddcd056SLinus Torvalds /* 12733ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 12743ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 12753ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 12763ddcd056SLinus Torvalds * for the common case. 12773ddcd056SLinus Torvalds */ 12787813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 12793ddcd056SLinus Torvalds { 12803ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 12813ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 12823ddcd056SLinus Torvalds return follow; 12833ddcd056SLinus Torvalds 12843ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 12853ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 12863ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 12873ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 12883ddcd056SLinus Torvalds } 12893ddcd056SLinus Torvalds return 0; 12903ddcd056SLinus Torvalds } 12913ddcd056SLinus Torvalds 1292ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1293ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1294ce57dfc1SAl Viro { 1295ce57dfc1SAl Viro struct inode *inode; 1296ce57dfc1SAl Viro int err; 1297ce57dfc1SAl Viro /* 1298ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1299ce57dfc1SAl Viro * to be able to know about the current root directory and 1300ce57dfc1SAl Viro * parent relationships. 1301ce57dfc1SAl Viro */ 1302ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1303ce57dfc1SAl Viro return handle_dots(nd, type); 1304ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1305ce57dfc1SAl Viro if (unlikely(err)) { 1306ce57dfc1SAl Viro terminate_walk(nd); 1307ce57dfc1SAl Viro return err; 1308ce57dfc1SAl Viro } 1309ce57dfc1SAl Viro if (!inode) { 1310ce57dfc1SAl Viro path_to_nameidata(path, nd); 1311ce57dfc1SAl Viro terminate_walk(nd); 1312ce57dfc1SAl Viro return -ENOENT; 1313ce57dfc1SAl Viro } 13147813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 131519660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 131619660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 131719660af7SAl Viro terminate_walk(nd); 1318ce57dfc1SAl Viro return -ECHILD; 131919660af7SAl Viro } 132019660af7SAl Viro } 1321ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1322ce57dfc1SAl Viro return 1; 1323ce57dfc1SAl Viro } 1324ce57dfc1SAl Viro path_to_nameidata(path, nd); 1325ce57dfc1SAl Viro nd->inode = inode; 1326ce57dfc1SAl Viro return 0; 1327ce57dfc1SAl Viro } 1328ce57dfc1SAl Viro 13291da177e4SLinus Torvalds /* 1330b356379aSAl Viro * This limits recursive symlink follows to 8, while 1331b356379aSAl Viro * limiting consecutive symlinks to 40. 1332b356379aSAl Viro * 1333b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1334b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1335b356379aSAl Viro */ 1336b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1337b356379aSAl Viro { 1338b356379aSAl Viro int res; 1339b356379aSAl Viro 1340b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1341b356379aSAl Viro path_put_conditional(path, nd); 1342b356379aSAl Viro path_put(&nd->path); 1343b356379aSAl Viro return -ELOOP; 1344b356379aSAl Viro } 13451a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1346b356379aSAl Viro 1347b356379aSAl Viro nd->depth++; 1348b356379aSAl Viro current->link_count++; 1349b356379aSAl Viro 1350b356379aSAl Viro do { 1351b356379aSAl Viro struct path link = *path; 1352b356379aSAl Viro void *cookie; 1353574197e0SAl Viro 1354574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1355b356379aSAl Viro if (!res) 1356b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1357b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1358574197e0SAl Viro put_link(nd, &link, cookie); 1359b356379aSAl Viro } while (res > 0); 1360b356379aSAl Viro 1361b356379aSAl Viro current->link_count--; 1362b356379aSAl Viro nd->depth--; 1363b356379aSAl Viro return res; 1364b356379aSAl Viro } 1365b356379aSAl Viro 1366b356379aSAl Viro /* 13673ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 13683ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 13693ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 13703ddcd056SLinus Torvalds * do lookup on this inode". 13713ddcd056SLinus Torvalds */ 13723ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 13733ddcd056SLinus Torvalds { 13743ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 13753ddcd056SLinus Torvalds return 1; 13763ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 13773ddcd056SLinus Torvalds return 0; 13783ddcd056SLinus Torvalds 13793ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 13803ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13813ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 13823ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13833ddcd056SLinus Torvalds return 1; 13843ddcd056SLinus Torvalds } 13853ddcd056SLinus Torvalds 1386bfcfaa77SLinus Torvalds /* 1387bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1388bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1389bfcfaa77SLinus Torvalds * 1390bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1391bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1392bfcfaa77SLinus Torvalds * fast. 1393bfcfaa77SLinus Torvalds * 1394bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1395bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1396bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1397bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1398bfcfaa77SLinus Torvalds * 1399bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1400bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1401bfcfaa77SLinus Torvalds * crossing operation. 1402bfcfaa77SLinus Torvalds * 1403bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1404bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1405bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1406bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1407bfcfaa77SLinus Torvalds */ 1408bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1409bfcfaa77SLinus Torvalds 1410bfcfaa77SLinus Torvalds #ifdef CONFIG_64BIT 1411bfcfaa77SLinus Torvalds 1412bfcfaa77SLinus Torvalds /* 1413bfcfaa77SLinus Torvalds * Jan Achrenius on G+: microoptimized version of 1414bfcfaa77SLinus Torvalds * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" 1415bfcfaa77SLinus Torvalds * that works for the bytemasks without having to 1416bfcfaa77SLinus Torvalds * mask them first. 1417bfcfaa77SLinus Torvalds */ 1418bfcfaa77SLinus Torvalds static inline long count_masked_bytes(unsigned long mask) 1419bfcfaa77SLinus Torvalds { 1420f7493e5dSLinus Torvalds return mask*0x0001020304050608ul >> 56; 1421bfcfaa77SLinus Torvalds } 1422bfcfaa77SLinus Torvalds 1423bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1424bfcfaa77SLinus Torvalds { 1425bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1426bfcfaa77SLinus Torvalds return hash; 1427bfcfaa77SLinus Torvalds } 1428bfcfaa77SLinus Torvalds 1429bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1430bfcfaa77SLinus Torvalds 1431bfcfaa77SLinus Torvalds /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ 1432bfcfaa77SLinus Torvalds static inline long count_masked_bytes(long mask) 1433bfcfaa77SLinus Torvalds { 1434bfcfaa77SLinus Torvalds /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ 1435bfcfaa77SLinus Torvalds long a = (0x0ff0001+mask) >> 23; 1436bfcfaa77SLinus Torvalds /* Fix the 1 for 00 case */ 1437bfcfaa77SLinus Torvalds return a & mask; 1438bfcfaa77SLinus Torvalds } 1439bfcfaa77SLinus Torvalds 1440bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1441bfcfaa77SLinus Torvalds 1442bfcfaa77SLinus Torvalds #endif 1443bfcfaa77SLinus Torvalds 1444bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1445bfcfaa77SLinus Torvalds { 1446bfcfaa77SLinus Torvalds unsigned long a, mask; 1447bfcfaa77SLinus Torvalds unsigned long hash = 0; 1448bfcfaa77SLinus Torvalds 1449bfcfaa77SLinus Torvalds for (;;) { 1450bfcfaa77SLinus Torvalds a = *(unsigned long *)name; 1451bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1452bfcfaa77SLinus Torvalds break; 1453bfcfaa77SLinus Torvalds hash += a; 1454f132c5beSAl Viro hash *= 9; 1455bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1456bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1457bfcfaa77SLinus Torvalds if (!len) 1458bfcfaa77SLinus Torvalds goto done; 1459bfcfaa77SLinus Torvalds } 1460bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1461bfcfaa77SLinus Torvalds hash += mask & a; 1462bfcfaa77SLinus Torvalds done: 1463bfcfaa77SLinus Torvalds return fold_hash(hash); 1464bfcfaa77SLinus Torvalds } 1465bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1466bfcfaa77SLinus Torvalds 1467989412bbSLinus Torvalds #define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) 1468989412bbSLinus Torvalds #define ONEBYTES REPEAT_BYTE(0x01) 1469989412bbSLinus Torvalds #define SLASHBYTES REPEAT_BYTE('/') 1470989412bbSLinus Torvalds #define HIGHBITS REPEAT_BYTE(0x80) 1471bfcfaa77SLinus Torvalds 1472bfcfaa77SLinus Torvalds /* Return the high bit set in the first byte that is a zero */ 1473bfcfaa77SLinus Torvalds static inline unsigned long has_zero(unsigned long a) 1474bfcfaa77SLinus Torvalds { 1475bfcfaa77SLinus Torvalds return ((a - ONEBYTES) & ~a) & HIGHBITS; 1476bfcfaa77SLinus Torvalds } 1477bfcfaa77SLinus Torvalds 1478bfcfaa77SLinus Torvalds /* 1479bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1480bfcfaa77SLinus Torvalds * return the length of the component; 1481bfcfaa77SLinus Torvalds */ 1482bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1483bfcfaa77SLinus Torvalds { 1484bfcfaa77SLinus Torvalds unsigned long a, mask, hash, len; 1485bfcfaa77SLinus Torvalds 1486bfcfaa77SLinus Torvalds hash = a = 0; 1487bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1488bfcfaa77SLinus Torvalds do { 1489bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1490bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1491bfcfaa77SLinus Torvalds a = *(unsigned long *)(name+len); 1492bfcfaa77SLinus Torvalds /* Do we have any NUL or '/' bytes in this word? */ 1493bfcfaa77SLinus Torvalds mask = has_zero(a) | has_zero(a ^ SLASHBYTES); 1494bfcfaa77SLinus Torvalds } while (!mask); 1495bfcfaa77SLinus Torvalds 1496bfcfaa77SLinus Torvalds /* The mask *below* the first high bit set */ 1497bfcfaa77SLinus Torvalds mask = (mask - 1) & ~mask; 1498bfcfaa77SLinus Torvalds mask >>= 7; 1499bfcfaa77SLinus Torvalds hash += a & mask; 1500bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1501bfcfaa77SLinus Torvalds 1502bfcfaa77SLinus Torvalds return len + count_masked_bytes(mask); 1503bfcfaa77SLinus Torvalds } 1504bfcfaa77SLinus Torvalds 1505bfcfaa77SLinus Torvalds #else 1506bfcfaa77SLinus Torvalds 15070145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 15080145acc2SLinus Torvalds { 15090145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 15100145acc2SLinus Torvalds while (len--) 15110145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 15120145acc2SLinus Torvalds return end_name_hash(hash); 15130145acc2SLinus Torvalds } 1514ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 15150145acc2SLinus Torvalds 15163ddcd056SLinus Torvalds /* 1517200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1518200e9ef7SLinus Torvalds * one character. 1519200e9ef7SLinus Torvalds */ 1520200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1521200e9ef7SLinus Torvalds { 1522200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1523200e9ef7SLinus Torvalds unsigned long len = 0, c; 1524200e9ef7SLinus Torvalds 1525200e9ef7SLinus Torvalds c = (unsigned char)*name; 1526200e9ef7SLinus Torvalds do { 1527200e9ef7SLinus Torvalds len++; 1528200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1529200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1530200e9ef7SLinus Torvalds } while (c && c != '/'); 1531200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1532200e9ef7SLinus Torvalds return len; 1533200e9ef7SLinus Torvalds } 1534200e9ef7SLinus Torvalds 1535bfcfaa77SLinus Torvalds #endif 1536bfcfaa77SLinus Torvalds 1537200e9ef7SLinus Torvalds /* 15381da177e4SLinus Torvalds * Name resolution. 1539ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1540ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 15411da177e4SLinus Torvalds * 1542ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1543ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 15441da177e4SLinus Torvalds */ 15456de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 15461da177e4SLinus Torvalds { 15471da177e4SLinus Torvalds struct path next; 15481da177e4SLinus Torvalds int err; 15491da177e4SLinus Torvalds 15501da177e4SLinus Torvalds while (*name=='/') 15511da177e4SLinus Torvalds name++; 15521da177e4SLinus Torvalds if (!*name) 1553086e183aSAl Viro return 0; 15541da177e4SLinus Torvalds 15551da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 15561da177e4SLinus Torvalds for(;;) { 15571da177e4SLinus Torvalds struct qstr this; 1558200e9ef7SLinus Torvalds long len; 1559fe479a58SAl Viro int type; 15601da177e4SLinus Torvalds 156152094c8aSAl Viro err = may_lookup(nd); 15621da177e4SLinus Torvalds if (err) 15631da177e4SLinus Torvalds break; 15641da177e4SLinus Torvalds 1565200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 15661da177e4SLinus Torvalds this.name = name; 1567200e9ef7SLinus Torvalds this.len = len; 15681da177e4SLinus Torvalds 1569fe479a58SAl Viro type = LAST_NORM; 1570200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1571fe479a58SAl Viro case 2: 1572200e9ef7SLinus Torvalds if (name[1] == '.') { 1573fe479a58SAl Viro type = LAST_DOTDOT; 157416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 157516c2cd71SAl Viro } 1576fe479a58SAl Viro break; 1577fe479a58SAl Viro case 1: 1578fe479a58SAl Viro type = LAST_DOT; 1579fe479a58SAl Viro } 15805a202bcdSAl Viro if (likely(type == LAST_NORM)) { 15815a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 158216c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 15835a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 15845a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 15855a202bcdSAl Viro &this); 15865a202bcdSAl Viro if (err < 0) 15875a202bcdSAl Viro break; 15885a202bcdSAl Viro } 15895a202bcdSAl Viro } 1590fe479a58SAl Viro 1591200e9ef7SLinus Torvalds if (!name[len]) 15921da177e4SLinus Torvalds goto last_component; 1593200e9ef7SLinus Torvalds /* 1594200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1595200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1596200e9ef7SLinus Torvalds */ 1597200e9ef7SLinus Torvalds do { 1598200e9ef7SLinus Torvalds len++; 1599200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1600200e9ef7SLinus Torvalds if (!name[len]) 1601b356379aSAl Viro goto last_component; 1602200e9ef7SLinus Torvalds name += len; 16031da177e4SLinus Torvalds 1604ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1605ce57dfc1SAl Viro if (err < 0) 1606ce57dfc1SAl Viro return err; 1607fe479a58SAl Viro 1608ce57dfc1SAl Viro if (err) { 1609b356379aSAl Viro err = nested_symlink(&next, nd); 16101da177e4SLinus Torvalds if (err) 1611a7472babSAl Viro return err; 161231e6b01fSNick Piggin } 16133ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 16141da177e4SLinus Torvalds continue; 16153ddcd056SLinus Torvalds err = -ENOTDIR; 16163ddcd056SLinus Torvalds break; 16171da177e4SLinus Torvalds /* here ends the main loop */ 16181da177e4SLinus Torvalds 16191da177e4SLinus Torvalds last_component: 1620ce57dfc1SAl Viro nd->last = this; 1621ce57dfc1SAl Viro nd->last_type = type; 1622ce57dfc1SAl Viro return 0; 1623ce57dfc1SAl Viro } 1624951361f9SAl Viro terminate_walk(nd); 16251da177e4SLinus Torvalds return err; 16261da177e4SLinus Torvalds } 16271da177e4SLinus Torvalds 162870e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 162970e9b357SAl Viro struct nameidata *nd, struct file **fp) 163031e6b01fSNick Piggin { 163131e6b01fSNick Piggin int retval = 0; 163231e6b01fSNick Piggin int fput_needed; 163331e6b01fSNick Piggin struct file *file; 163431e6b01fSNick Piggin 163531e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 163616c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 163731e6b01fSNick Piggin nd->depth = 0; 16385b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 16395b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 164073d049a4SAl Viro if (*name) { 16415b6ca027SAl Viro if (!inode->i_op->lookup) 16425b6ca027SAl Viro return -ENOTDIR; 16435b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 16445b6ca027SAl Viro if (retval) 16455b6ca027SAl Viro return retval; 164673d049a4SAl Viro } 16475b6ca027SAl Viro nd->path = nd->root; 16485b6ca027SAl Viro nd->inode = inode; 16495b6ca027SAl Viro if (flags & LOOKUP_RCU) { 16505b6ca027SAl Viro br_read_lock(vfsmount_lock); 16515b6ca027SAl Viro rcu_read_lock(); 16525b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 16535b6ca027SAl Viro } else { 16545b6ca027SAl Viro path_get(&nd->path); 16555b6ca027SAl Viro } 16565b6ca027SAl Viro return 0; 16575b6ca027SAl Viro } 16585b6ca027SAl Viro 165931e6b01fSNick Piggin nd->root.mnt = NULL; 166031e6b01fSNick Piggin 166131e6b01fSNick Piggin if (*name=='/') { 1662e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 166331e6b01fSNick Piggin br_read_lock(vfsmount_lock); 166431e6b01fSNick Piggin rcu_read_lock(); 1665e41f7d4eSAl Viro set_root_rcu(nd); 1666e41f7d4eSAl Viro } else { 1667e41f7d4eSAl Viro set_root(nd); 1668e41f7d4eSAl Viro path_get(&nd->root); 1669e41f7d4eSAl Viro } 167031e6b01fSNick Piggin nd->path = nd->root; 167131e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1672e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 167331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1674c28cc364SNick Piggin unsigned seq; 167531e6b01fSNick Piggin 167631e6b01fSNick Piggin br_read_lock(vfsmount_lock); 167731e6b01fSNick Piggin rcu_read_lock(); 167831e6b01fSNick Piggin 1679c28cc364SNick Piggin do { 1680c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 168131e6b01fSNick Piggin nd->path = fs->pwd; 1682c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1683c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1684e41f7d4eSAl Viro } else { 1685e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1686e41f7d4eSAl Viro } 168731e6b01fSNick Piggin } else { 168831e6b01fSNick Piggin struct dentry *dentry; 168931e6b01fSNick Piggin 16901abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 169131e6b01fSNick Piggin retval = -EBADF; 169231e6b01fSNick Piggin if (!file) 169331e6b01fSNick Piggin goto out_fail; 169431e6b01fSNick Piggin 169531e6b01fSNick Piggin dentry = file->f_path.dentry; 169631e6b01fSNick Piggin 1697f52e0c11SAl Viro if (*name) { 169831e6b01fSNick Piggin retval = -ENOTDIR; 169931e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 170031e6b01fSNick Piggin goto fput_fail; 170131e6b01fSNick Piggin 17024ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 170331e6b01fSNick Piggin if (retval) 170431e6b01fSNick Piggin goto fput_fail; 1705f52e0c11SAl Viro } 170631e6b01fSNick Piggin 170731e6b01fSNick Piggin nd->path = file->f_path; 1708e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 170931e6b01fSNick Piggin if (fput_needed) 171070e9b357SAl Viro *fp = file; 1711c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 171231e6b01fSNick Piggin br_read_lock(vfsmount_lock); 171331e6b01fSNick Piggin rcu_read_lock(); 17145590ff0dSUlrich Drepper } else { 17155dd784d0SJan Blunck path_get(&file->f_path); 17165590ff0dSUlrich Drepper fput_light(file, fput_needed); 17171da177e4SLinus Torvalds } 1718e41f7d4eSAl Viro } 1719e41f7d4eSAl Viro 172031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17219b4a9b14SAl Viro return 0; 17222dfdd266SJosef 'Jeff' Sipek 17239b4a9b14SAl Viro fput_fail: 17249b4a9b14SAl Viro fput_light(file, fput_needed); 17259b4a9b14SAl Viro out_fail: 17269b4a9b14SAl Viro return retval; 17279b4a9b14SAl Viro } 17289b4a9b14SAl Viro 1729bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1730bd92d7feSAl Viro { 1731bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1732bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1733bd92d7feSAl Viro 1734bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1735bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1736bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1737bd92d7feSAl Viro } 1738bd92d7feSAl Viro 17399b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1740ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 17419b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17429b4a9b14SAl Viro { 174370e9b357SAl Viro struct file *base = NULL; 1744bd92d7feSAl Viro struct path path; 1745bd92d7feSAl Viro int err; 174631e6b01fSNick Piggin 174731e6b01fSNick Piggin /* 174831e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 174931e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 175031e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 175131e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 175231e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 175331e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 175431e6b01fSNick Piggin * analogue, foo_rcu(). 175531e6b01fSNick Piggin * 175631e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 175731e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 175831e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 175931e6b01fSNick Piggin * be able to complete). 176031e6b01fSNick Piggin */ 1761bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1762ee0827cdSAl Viro 1763bd92d7feSAl Viro if (unlikely(err)) 1764bd92d7feSAl Viro return err; 1765ee0827cdSAl Viro 1766ee0827cdSAl Viro current->total_link_count = 0; 1767bd92d7feSAl Viro err = link_path_walk(name, nd); 1768bd92d7feSAl Viro 1769bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1770bd92d7feSAl Viro err = lookup_last(nd, &path); 1771bd92d7feSAl Viro while (err > 0) { 1772bd92d7feSAl Viro void *cookie; 1773bd92d7feSAl Viro struct path link = path; 1774bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1775574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1776bd92d7feSAl Viro if (!err) 1777bd92d7feSAl Viro err = lookup_last(nd, &path); 1778574197e0SAl Viro put_link(nd, &link, cookie); 1779bd92d7feSAl Viro } 1780bd92d7feSAl Viro } 1781ee0827cdSAl Viro 17829f1fafeeSAl Viro if (!err) 17839f1fafeeSAl Viro err = complete_walk(nd); 1784bd92d7feSAl Viro 1785bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1786bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1787bd92d7feSAl Viro path_put(&nd->path); 1788bd23a539SAl Viro err = -ENOTDIR; 1789bd92d7feSAl Viro } 1790bd92d7feSAl Viro } 179116c2cd71SAl Viro 179270e9b357SAl Viro if (base) 179370e9b357SAl Viro fput(base); 1794ee0827cdSAl Viro 17955b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 179631e6b01fSNick Piggin path_put(&nd->root); 179731e6b01fSNick Piggin nd->root.mnt = NULL; 179831e6b01fSNick Piggin } 1799bd92d7feSAl Viro return err; 180031e6b01fSNick Piggin } 180131e6b01fSNick Piggin 1802ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1803ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1804ee0827cdSAl Viro { 1805ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1806ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1807ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1808ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1809ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1810ee0827cdSAl Viro 181131e6b01fSNick Piggin if (likely(!retval)) { 181231e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 181331e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 181431e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 181531e6b01fSNick Piggin } 181631e6b01fSNick Piggin } 1817170aa3d0SUlrich Drepper return retval; 18181da177e4SLinus Torvalds } 18191da177e4SLinus Torvalds 1820c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 18215590ff0dSUlrich Drepper { 1822c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 18235590ff0dSUlrich Drepper } 18245590ff0dSUlrich Drepper 1825d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1826d1811465SAl Viro { 1827d1811465SAl Viro struct nameidata nd; 1828d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1829d1811465SAl Viro if (!res) 1830d1811465SAl Viro *path = nd.path; 1831d1811465SAl Viro return res; 1832d1811465SAl Viro } 1833d1811465SAl Viro 183416f18200SJosef 'Jeff' Sipek /** 183516f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 183616f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 183716f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 183816f18200SJosef 'Jeff' Sipek * @name: pointer to file name 183916f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1840e0a01249SAl Viro * @path: pointer to struct path to fill 184116f18200SJosef 'Jeff' Sipek */ 184216f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 184316f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1844e0a01249SAl Viro struct path *path) 184516f18200SJosef 'Jeff' Sipek { 1846e0a01249SAl Viro struct nameidata nd; 1847e0a01249SAl Viro int err; 1848e0a01249SAl Viro nd.root.dentry = dentry; 1849e0a01249SAl Viro nd.root.mnt = mnt; 1850e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18515b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1852e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1853e0a01249SAl Viro if (!err) 1854e0a01249SAl Viro *path = nd.path; 1855e0a01249SAl Viro return err; 185616f18200SJosef 'Jeff' Sipek } 185716f18200SJosef 'Jeff' Sipek 1858057f6c01SJames Morris /* 1859057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1860057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1861057f6c01SJames Morris * SMP-safe. 1862057f6c01SJames Morris */ 1863a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 18641da177e4SLinus Torvalds { 18654ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 18661da177e4SLinus Torvalds } 18671da177e4SLinus Torvalds 1868eead1911SChristoph Hellwig /** 1869a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1870eead1911SChristoph Hellwig * @name: pathname component to lookup 1871eead1911SChristoph Hellwig * @base: base directory to lookup from 1872eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1873eead1911SChristoph Hellwig * 1874a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1875a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1876eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1877eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1878eead1911SChristoph Hellwig */ 1879057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1880057f6c01SJames Morris { 1881057f6c01SJames Morris struct qstr this; 18826a96ba54SAl Viro unsigned int c; 1883cda309deSMiklos Szeredi int err; 1884057f6c01SJames Morris 18852f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 18862f9092e1SDavid Woodhouse 18876a96ba54SAl Viro this.name = name; 18886a96ba54SAl Viro this.len = len; 18890145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 18906a96ba54SAl Viro if (!len) 18916a96ba54SAl Viro return ERR_PTR(-EACCES); 18926a96ba54SAl Viro 18936a96ba54SAl Viro while (len--) { 18946a96ba54SAl Viro c = *(const unsigned char *)name++; 18956a96ba54SAl Viro if (c == '/' || c == '\0') 18966a96ba54SAl Viro return ERR_PTR(-EACCES); 18976a96ba54SAl Viro } 18985a202bcdSAl Viro /* 18995a202bcdSAl Viro * See if the low-level filesystem might want 19005a202bcdSAl Viro * to use its own hash.. 19015a202bcdSAl Viro */ 19025a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 19035a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 19045a202bcdSAl Viro if (err < 0) 19055a202bcdSAl Viro return ERR_PTR(err); 19065a202bcdSAl Viro } 1907eead1911SChristoph Hellwig 1908cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 1909cda309deSMiklos Szeredi if (err) 1910cda309deSMiklos Szeredi return ERR_PTR(err); 1911cda309deSMiklos Szeredi 191249705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1913057f6c01SJames Morris } 1914057f6c01SJames Morris 19151fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 19161fa1e7f6SAndy Whitcroft struct path *path, int *empty) 19171da177e4SLinus Torvalds { 19182d8f3038SAl Viro struct nameidata nd; 19191fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 19201da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19211da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19222d8f3038SAl Viro 19232d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19242d8f3038SAl Viro 19252d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19261da177e4SLinus Torvalds putname(tmp); 19272d8f3038SAl Viro if (!err) 19282d8f3038SAl Viro *path = nd.path; 19291da177e4SLinus Torvalds } 19301da177e4SLinus Torvalds return err; 19311da177e4SLinus Torvalds } 19321da177e4SLinus Torvalds 19331fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 19341fa1e7f6SAndy Whitcroft struct path *path) 19351fa1e7f6SAndy Whitcroft { 1936f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 19371fa1e7f6SAndy Whitcroft } 19381fa1e7f6SAndy Whitcroft 19392ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 19402ad94ae6SAl Viro struct nameidata *nd, char **name) 19412ad94ae6SAl Viro { 19422ad94ae6SAl Viro char *s = getname(path); 19432ad94ae6SAl Viro int error; 19442ad94ae6SAl Viro 19452ad94ae6SAl Viro if (IS_ERR(s)) 19462ad94ae6SAl Viro return PTR_ERR(s); 19472ad94ae6SAl Viro 19482ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 19492ad94ae6SAl Viro if (error) 19502ad94ae6SAl Viro putname(s); 19512ad94ae6SAl Viro else 19522ad94ae6SAl Viro *name = s; 19532ad94ae6SAl Viro 19542ad94ae6SAl Viro return error; 19552ad94ae6SAl Viro } 19562ad94ae6SAl Viro 19571da177e4SLinus Torvalds /* 19581da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 19591da177e4SLinus Torvalds * minimal. 19601da177e4SLinus Torvalds */ 19611da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 19621da177e4SLinus Torvalds { 1963da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1964da9592edSDavid Howells 19651da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 19661da177e4SLinus Torvalds return 0; 1967e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1968e795b717SSerge E. Hallyn goto other_userns; 1969da9592edSDavid Howells if (inode->i_uid == fsuid) 19701da177e4SLinus Torvalds return 0; 1971da9592edSDavid Howells if (dir->i_uid == fsuid) 19721da177e4SLinus Torvalds return 0; 1973e795b717SSerge E. Hallyn 1974e795b717SSerge E. Hallyn other_userns: 1975e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 19761da177e4SLinus Torvalds } 19771da177e4SLinus Torvalds 19781da177e4SLinus Torvalds /* 19791da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 19801da177e4SLinus Torvalds * whether the type of victim is right. 19811da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 19821da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 19831da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 19841da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 19851da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 19861da177e4SLinus Torvalds * a. be owner of dir, or 19871da177e4SLinus Torvalds * b. be owner of victim, or 19881da177e4SLinus Torvalds * c. have CAP_FOWNER capability 19891da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 19901da177e4SLinus Torvalds * links pointing to it. 19911da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 19921da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 19931da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 19941da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 19951da177e4SLinus Torvalds * nfs_async_unlink(). 19961da177e4SLinus Torvalds */ 1997858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 19981da177e4SLinus Torvalds { 19991da177e4SLinus Torvalds int error; 20001da177e4SLinus Torvalds 20011da177e4SLinus Torvalds if (!victim->d_inode) 20021da177e4SLinus Torvalds return -ENOENT; 20031da177e4SLinus Torvalds 20041da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2005cccc6bbaSAl Viro audit_inode_child(victim, dir); 20061da177e4SLinus Torvalds 2007f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20081da177e4SLinus Torvalds if (error) 20091da177e4SLinus Torvalds return error; 20101da177e4SLinus Torvalds if (IS_APPEND(dir)) 20111da177e4SLinus Torvalds return -EPERM; 20121da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2013f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20141da177e4SLinus Torvalds return -EPERM; 20151da177e4SLinus Torvalds if (isdir) { 20161da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20171da177e4SLinus Torvalds return -ENOTDIR; 20181da177e4SLinus Torvalds if (IS_ROOT(victim)) 20191da177e4SLinus Torvalds return -EBUSY; 20201da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20211da177e4SLinus Torvalds return -EISDIR; 20221da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20231da177e4SLinus Torvalds return -ENOENT; 20241da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20251da177e4SLinus Torvalds return -EBUSY; 20261da177e4SLinus Torvalds return 0; 20271da177e4SLinus Torvalds } 20281da177e4SLinus Torvalds 20291da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20301da177e4SLinus Torvalds * dir. 20311da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20321da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20331da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20341da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20351da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20361da177e4SLinus Torvalds */ 2037a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 20381da177e4SLinus Torvalds { 20391da177e4SLinus Torvalds if (child->d_inode) 20401da177e4SLinus Torvalds return -EEXIST; 20411da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20421da177e4SLinus Torvalds return -ENOENT; 2043f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 20441da177e4SLinus Torvalds } 20451da177e4SLinus Torvalds 20461da177e4SLinus Torvalds /* 20471da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 20481da177e4SLinus Torvalds */ 20491da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 20501da177e4SLinus Torvalds { 20511da177e4SLinus Torvalds struct dentry *p; 20521da177e4SLinus Torvalds 20531da177e4SLinus Torvalds if (p1 == p2) { 2054f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 20551da177e4SLinus Torvalds return NULL; 20561da177e4SLinus Torvalds } 20571da177e4SLinus Torvalds 2058a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20591da177e4SLinus Torvalds 2060e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2061e2761a11SOGAWA Hirofumi if (p) { 2062f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2063f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 20641da177e4SLinus Torvalds return p; 20651da177e4SLinus Torvalds } 20661da177e4SLinus Torvalds 2067e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2068e2761a11SOGAWA Hirofumi if (p) { 2069f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2070f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20711da177e4SLinus Torvalds return p; 20721da177e4SLinus Torvalds } 20731da177e4SLinus Torvalds 2074f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2075f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20761da177e4SLinus Torvalds return NULL; 20771da177e4SLinus Torvalds } 20781da177e4SLinus Torvalds 20791da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 20801da177e4SLinus Torvalds { 20811b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 20821da177e4SLinus Torvalds if (p1 != p2) { 20831b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2084a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20851da177e4SLinus Torvalds } 20861da177e4SLinus Torvalds } 20871da177e4SLinus Torvalds 20884acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 20891da177e4SLinus Torvalds struct nameidata *nd) 20901da177e4SLinus Torvalds { 2091a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20921da177e4SLinus Torvalds 20931da177e4SLinus Torvalds if (error) 20941da177e4SLinus Torvalds return error; 20951da177e4SLinus Torvalds 2096acfa4380SAl Viro if (!dir->i_op->create) 20971da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 20981da177e4SLinus Torvalds mode &= S_IALLUGO; 20991da177e4SLinus Torvalds mode |= S_IFREG; 21001da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 21011da177e4SLinus Torvalds if (error) 21021da177e4SLinus Torvalds return error; 21031da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 2104a74574aaSStephen Smalley if (!error) 2105f38aa942SAmy Griffis fsnotify_create(dir, dentry); 21061da177e4SLinus Torvalds return error; 21071da177e4SLinus Torvalds } 21081da177e4SLinus Torvalds 210973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 21101da177e4SLinus Torvalds { 21113fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21121da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21131da177e4SLinus Torvalds int error; 21141da177e4SLinus Torvalds 2115bcda7652SAl Viro /* O_PATH? */ 2116bcda7652SAl Viro if (!acc_mode) 2117bcda7652SAl Viro return 0; 2118bcda7652SAl Viro 21191da177e4SLinus Torvalds if (!inode) 21201da177e4SLinus Torvalds return -ENOENT; 21211da177e4SLinus Torvalds 2122c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2123c8fe8f30SChristoph Hellwig case S_IFLNK: 21241da177e4SLinus Torvalds return -ELOOP; 2125c8fe8f30SChristoph Hellwig case S_IFDIR: 2126c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21271da177e4SLinus Torvalds return -EISDIR; 2128c8fe8f30SChristoph Hellwig break; 2129c8fe8f30SChristoph Hellwig case S_IFBLK: 2130c8fe8f30SChristoph Hellwig case S_IFCHR: 21313fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21321da177e4SLinus Torvalds return -EACCES; 2133c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2134c8fe8f30SChristoph Hellwig case S_IFIFO: 2135c8fe8f30SChristoph Hellwig case S_IFSOCK: 21361da177e4SLinus Torvalds flag &= ~O_TRUNC; 2137c8fe8f30SChristoph Hellwig break; 21384a3fd211SDave Hansen } 2139b41572e9SDave Hansen 21403fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2141b41572e9SDave Hansen if (error) 2142b41572e9SDave Hansen return error; 21436146f0d5SMimi Zohar 21441da177e4SLinus Torvalds /* 21451da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 21461da177e4SLinus Torvalds */ 21471da177e4SLinus Torvalds if (IS_APPEND(inode)) { 21488737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 21497715b521SAl Viro return -EPERM; 21501da177e4SLinus Torvalds if (flag & O_TRUNC) 21517715b521SAl Viro return -EPERM; 21521da177e4SLinus Torvalds } 21531da177e4SLinus Torvalds 21541da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 21552e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 21567715b521SAl Viro return -EPERM; 21571da177e4SLinus Torvalds 2158f3c7691eSJ. Bruce Fields return 0; 21597715b521SAl Viro } 21607715b521SAl Viro 2161e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 21627715b521SAl Viro { 2163e1181ee6SJeff Layton struct path *path = &filp->f_path; 21647715b521SAl Viro struct inode *inode = path->dentry->d_inode; 21657715b521SAl Viro int error = get_write_access(inode); 21661da177e4SLinus Torvalds if (error) 21677715b521SAl Viro return error; 21681da177e4SLinus Torvalds /* 21691da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 21701da177e4SLinus Torvalds */ 21711da177e4SLinus Torvalds error = locks_verify_locked(inode); 2172be6d3e56SKentaro Takeda if (!error) 2173ea0d3ab2STetsuo Handa error = security_path_truncate(path); 21741da177e4SLinus Torvalds if (!error) { 21757715b521SAl Viro error = do_truncate(path->dentry, 0, 2176d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2177e1181ee6SJeff Layton filp); 21781da177e4SLinus Torvalds } 21791da177e4SLinus Torvalds put_write_access(inode); 2180acd0c935SMimi Zohar return error; 21811da177e4SLinus Torvalds } 21821da177e4SLinus Torvalds 2183d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2184d57999e1SDave Hansen { 21858a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 21868a5e929dSAl Viro flag--; 2187d57999e1SDave Hansen return flag; 2188d57999e1SDave Hansen } 2189d57999e1SDave Hansen 219031e6b01fSNick Piggin /* 2191fe2d35ffSAl Viro * Handle the last step of open() 219231e6b01fSNick Piggin */ 2193fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2194c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2195fb1cc555SAl Viro { 2196a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 21976c0d46c4SAl Viro struct dentry *dentry; 2198ca344a89SAl Viro int open_flag = op->open_flag; 21996c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2200ca344a89SAl Viro int want_write = 0; 2201bcda7652SAl Viro int acc_mode = op->acc_mode; 2202fb1cc555SAl Viro struct file *filp; 220316c2cd71SAl Viro int error; 2204fb1cc555SAl Viro 2205c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2206c3e380b0SAl Viro nd->flags |= op->intent; 2207c3e380b0SAl Viro 22081f36f774SAl Viro switch (nd->last_type) { 22091f36f774SAl Viro case LAST_DOTDOT: 2210176306f5SNeil Brown case LAST_DOT: 2211fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2212fe2d35ffSAl Viro if (error) 2213fe2d35ffSAl Viro return ERR_PTR(error); 22141f36f774SAl Viro /* fallthrough */ 22151f36f774SAl Viro case LAST_ROOT: 22169f1fafeeSAl Viro error = complete_walk(nd); 221716c2cd71SAl Viro if (error) 22189f1fafeeSAl Viro return ERR_PTR(error); 2219fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2220ca344a89SAl Viro if (open_flag & O_CREAT) { 222116c2cd71SAl Viro error = -EISDIR; 22221f36f774SAl Viro goto exit; 2223fe2d35ffSAl Viro } 2224fe2d35ffSAl Viro goto ok; 22251f36f774SAl Viro case LAST_BIND: 22269f1fafeeSAl Viro error = complete_walk(nd); 222716c2cd71SAl Viro if (error) 22289f1fafeeSAl Viro return ERR_PTR(error); 22291f36f774SAl Viro audit_inode(pathname, dir); 22301f36f774SAl Viro goto ok; 22311f36f774SAl Viro } 2232a2c36b45SAl Viro 2233ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2234bcda7652SAl Viro int symlink_ok = 0; 2235fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2236fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2237bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2238bcda7652SAl Viro symlink_ok = 1; 2239fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2240ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2241ce57dfc1SAl Viro !symlink_ok); 2242ce57dfc1SAl Viro if (error < 0) 2243fe2d35ffSAl Viro return ERR_PTR(error); 2244ce57dfc1SAl Viro if (error) /* symlink */ 2245fe2d35ffSAl Viro return NULL; 2246fe2d35ffSAl Viro /* sayonara */ 22479f1fafeeSAl Viro error = complete_walk(nd); 22489f1fafeeSAl Viro if (error) 22497f6c7e62SMiklos Szeredi return ERR_PTR(error); 2250fe2d35ffSAl Viro 2251fe2d35ffSAl Viro error = -ENOTDIR; 2252fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2253ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2254fe2d35ffSAl Viro goto exit; 2255fe2d35ffSAl Viro } 2256fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2257fe2d35ffSAl Viro goto ok; 2258fe2d35ffSAl Viro } 2259fe2d35ffSAl Viro 2260fe2d35ffSAl Viro /* create side of things */ 2261a3fbbde7SAl Viro /* 2262a3fbbde7SAl Viro * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been 2263a3fbbde7SAl Viro * cleared when we got to the last component we are about to look up 2264a3fbbde7SAl Viro */ 22659f1fafeeSAl Viro error = complete_walk(nd); 22669f1fafeeSAl Viro if (error) 22679f1fafeeSAl Viro return ERR_PTR(error); 2268fe2d35ffSAl Viro 2269fe2d35ffSAl Viro audit_inode(pathname, dir); 227016c2cd71SAl Viro error = -EISDIR; 22711f36f774SAl Viro /* trailing slashes? */ 227231e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 22731f36f774SAl Viro goto exit; 22741f36f774SAl Viro 2275a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2276a1e28038SAl Viro 22776c0d46c4SAl Viro dentry = lookup_hash(nd); 22786c0d46c4SAl Viro error = PTR_ERR(dentry); 22796c0d46c4SAl Viro if (IS_ERR(dentry)) { 2280fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2281fb1cc555SAl Viro goto exit; 2282fb1cc555SAl Viro } 2283fb1cc555SAl Viro 22846c0d46c4SAl Viro path->dentry = dentry; 22856c0d46c4SAl Viro path->mnt = nd->path.mnt; 22866c0d46c4SAl Viro 2287fb1cc555SAl Viro /* Negative dentry, just create the file */ 22886c0d46c4SAl Viro if (!dentry->d_inode) { 2289a218d0fdSAl Viro umode_t mode = op->mode; 22906c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 22916c0d46c4SAl Viro mode &= ~current_umask(); 2292fb1cc555SAl Viro /* 2293fb1cc555SAl Viro * This write is needed to ensure that a 22946c0d46c4SAl Viro * rw->ro transition does not occur between 2295fb1cc555SAl Viro * the time when the file is created and when 2296fb1cc555SAl Viro * a permanent write count is taken through 2297fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2298fb1cc555SAl Viro */ 2299fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2300fb1cc555SAl Viro if (error) 2301fb1cc555SAl Viro goto exit_mutex_unlock; 2302ca344a89SAl Viro want_write = 1; 23039b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2304ca344a89SAl Viro open_flag &= ~O_TRUNC; 23056c0d46c4SAl Viro will_truncate = 0; 2306bcda7652SAl Viro acc_mode = MAY_OPEN; 23076c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 23086c0d46c4SAl Viro if (error) 23096c0d46c4SAl Viro goto exit_mutex_unlock; 23106c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 23116c0d46c4SAl Viro if (error) 23126c0d46c4SAl Viro goto exit_mutex_unlock; 23136c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 23146c0d46c4SAl Viro dput(nd->path.dentry); 23156c0d46c4SAl Viro nd->path.dentry = dentry; 2316ca344a89SAl Viro goto common; 2317fb1cc555SAl Viro } 2318fb1cc555SAl Viro 2319fb1cc555SAl Viro /* 2320fb1cc555SAl Viro * It already exists. 2321fb1cc555SAl Viro */ 2322fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2323fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2324fb1cc555SAl Viro 2325fb1cc555SAl Viro error = -EEXIST; 2326ca344a89SAl Viro if (open_flag & O_EXCL) 2327fb1cc555SAl Viro goto exit_dput; 2328fb1cc555SAl Viro 23299875cf80SDavid Howells error = follow_managed(path, nd->flags); 23309875cf80SDavid Howells if (error < 0) 2331fb1cc555SAl Viro goto exit_dput; 2332fb1cc555SAl Viro 2333a3fbbde7SAl Viro if (error) 2334a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2335a3fbbde7SAl Viro 2336fb1cc555SAl Viro error = -ENOENT; 2337fb1cc555SAl Viro if (!path->dentry->d_inode) 2338fb1cc555SAl Viro goto exit_dput; 23399e67f361SAl Viro 23409e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2341fb1cc555SAl Viro return NULL; 2342fb1cc555SAl Viro 2343fb1cc555SAl Viro path_to_nameidata(path, nd); 234431e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2345a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2346a3fbbde7SAl Viro error = complete_walk(nd); 2347a3fbbde7SAl Viro if (error) 2348097b180cSMiklos Szeredi return ERR_PTR(error); 2349fb1cc555SAl Viro error = -EISDIR; 235031e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2351fb1cc555SAl Viro goto exit; 235267ee3ad2SAl Viro ok: 23536c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 23546c0d46c4SAl Viro will_truncate = 0; 23556c0d46c4SAl Viro 23560f9d1a10SAl Viro if (will_truncate) { 23570f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 23580f9d1a10SAl Viro if (error) 23590f9d1a10SAl Viro goto exit; 2360ca344a89SAl Viro want_write = 1; 23610f9d1a10SAl Viro } 2362ca344a89SAl Viro common: 2363bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2364ca344a89SAl Viro if (error) 23650f9d1a10SAl Viro goto exit; 23660f9d1a10SAl Viro filp = nameidata_to_filp(nd); 23670f9d1a10SAl Viro if (!IS_ERR(filp)) { 23680f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 23690f9d1a10SAl Viro if (error) { 23700f9d1a10SAl Viro fput(filp); 23710f9d1a10SAl Viro filp = ERR_PTR(error); 23720f9d1a10SAl Viro } 23730f9d1a10SAl Viro } 23740f9d1a10SAl Viro if (!IS_ERR(filp)) { 23750f9d1a10SAl Viro if (will_truncate) { 23760f9d1a10SAl Viro error = handle_truncate(filp); 23770f9d1a10SAl Viro if (error) { 23780f9d1a10SAl Viro fput(filp); 23790f9d1a10SAl Viro filp = ERR_PTR(error); 23800f9d1a10SAl Viro } 23810f9d1a10SAl Viro } 23820f9d1a10SAl Viro } 2383ca344a89SAl Viro out: 2384ca344a89SAl Viro if (want_write) 23850f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 23860f9d1a10SAl Viro path_put(&nd->path); 2387fb1cc555SAl Viro return filp; 2388fb1cc555SAl Viro 2389fb1cc555SAl Viro exit_mutex_unlock: 2390fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2391fb1cc555SAl Viro exit_dput: 2392fb1cc555SAl Viro path_put_conditional(path, nd); 2393fb1cc555SAl Viro exit: 2394ca344a89SAl Viro filp = ERR_PTR(error); 2395ca344a89SAl Viro goto out; 2396fb1cc555SAl Viro } 2397fb1cc555SAl Viro 239813aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 239973d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 24001da177e4SLinus Torvalds { 2401fe2d35ffSAl Viro struct file *base = NULL; 24024a3fd211SDave Hansen struct file *filp; 24039850c056SAl Viro struct path path; 240413aab428SAl Viro int error; 240531e6b01fSNick Piggin 240631e6b01fSNick Piggin filp = get_empty_filp(); 240731e6b01fSNick Piggin if (!filp) 240831e6b01fSNick Piggin return ERR_PTR(-ENFILE); 240931e6b01fSNick Piggin 241047c805dcSAl Viro filp->f_flags = op->open_flag; 241173d049a4SAl Viro nd->intent.open.file = filp; 241273d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 241373d049a4SAl Viro nd->intent.open.create_mode = op->mode; 241431e6b01fSNick Piggin 241573d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 241631e6b01fSNick Piggin if (unlikely(error)) 241713aab428SAl Viro goto out_filp; 241831e6b01fSNick Piggin 2419fe2d35ffSAl Viro current->total_link_count = 0; 242073d049a4SAl Viro error = link_path_walk(pathname, nd); 242131e6b01fSNick Piggin if (unlikely(error)) 242231e6b01fSNick Piggin goto out_filp; 24231da177e4SLinus Torvalds 242473d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2425806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 24267b9337aaSNick Piggin struct path link = path; 2427def4af30SAl Viro void *cookie; 2428574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 242973d049a4SAl Viro path_put_conditional(&path, nd); 243073d049a4SAl Viro path_put(&nd->path); 243140b39136SAl Viro filp = ERR_PTR(-ELOOP); 243240b39136SAl Viro break; 243340b39136SAl Viro } 243473d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 243573d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2436574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2437c3e380b0SAl Viro if (unlikely(error)) 2438f1afe9efSAl Viro filp = ERR_PTR(error); 2439c3e380b0SAl Viro else 244073d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2441574197e0SAl Viro put_link(nd, &link, cookie); 2442806b681cSAl Viro } 244310fa8e62SAl Viro out: 244473d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 244573d049a4SAl Viro path_put(&nd->root); 2446fe2d35ffSAl Viro if (base) 2447fe2d35ffSAl Viro fput(base); 244873d049a4SAl Viro release_open_intent(nd); 244910fa8e62SAl Viro return filp; 24501da177e4SLinus Torvalds 245131e6b01fSNick Piggin out_filp: 245210fa8e62SAl Viro filp = ERR_PTR(error); 245310fa8e62SAl Viro goto out; 2454de459215SKirill Korotaev } 24551da177e4SLinus Torvalds 245613aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 245713aab428SAl Viro const struct open_flags *op, int flags) 245813aab428SAl Viro { 245973d049a4SAl Viro struct nameidata nd; 246013aab428SAl Viro struct file *filp; 246113aab428SAl Viro 246273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 246313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 246473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 246513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 246673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 246713aab428SAl Viro return filp; 246813aab428SAl Viro } 246913aab428SAl Viro 247073d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 247173d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 247273d049a4SAl Viro { 247373d049a4SAl Viro struct nameidata nd; 247473d049a4SAl Viro struct file *file; 247573d049a4SAl Viro 247673d049a4SAl Viro nd.root.mnt = mnt; 247773d049a4SAl Viro nd.root.dentry = dentry; 247873d049a4SAl Viro 247973d049a4SAl Viro flags |= LOOKUP_ROOT; 248073d049a4SAl Viro 2481bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 248273d049a4SAl Viro return ERR_PTR(-ELOOP); 248373d049a4SAl Viro 248473d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 248573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 248673d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 248773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 248873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 248973d049a4SAl Viro return file; 249073d049a4SAl Viro } 249173d049a4SAl Viro 2492ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 24931da177e4SLinus Torvalds { 2494c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2495ed75e95dSAl Viro struct nameidata nd; 2496ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2497ed75e95dSAl Viro if (error) 2498ed75e95dSAl Viro return ERR_PTR(error); 24991da177e4SLinus Torvalds 2500c663e5d8SChristoph Hellwig /* 2501c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2502c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2503c663e5d8SChristoph Hellwig */ 2504ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2505ed75e95dSAl Viro goto out; 2506ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2507ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2508ed75e95dSAl Viro nd.intent.open.flags = O_EXCL; 2509c663e5d8SChristoph Hellwig 2510c663e5d8SChristoph Hellwig /* 2511c663e5d8SChristoph Hellwig * Do the final lookup. 2512c663e5d8SChristoph Hellwig */ 2513ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2514ed75e95dSAl Viro dentry = lookup_hash(&nd); 25151da177e4SLinus Torvalds if (IS_ERR(dentry)) 25161da177e4SLinus Torvalds goto fail; 2517c663e5d8SChristoph Hellwig 2518e9baf6e5SAl Viro if (dentry->d_inode) 2519e9baf6e5SAl Viro goto eexist; 2520c663e5d8SChristoph Hellwig /* 2521c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2522c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2523c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2524c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2525c663e5d8SChristoph Hellwig */ 2526ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 25271da177e4SLinus Torvalds dput(dentry); 25281da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2529ed75e95dSAl Viro goto fail; 2530e9baf6e5SAl Viro } 2531ed75e95dSAl Viro *path = nd.path; 2532e9baf6e5SAl Viro return dentry; 2533e9baf6e5SAl Viro eexist: 2534e9baf6e5SAl Viro dput(dentry); 2535e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 25361da177e4SLinus Torvalds fail: 2537dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2538ed75e95dSAl Viro out: 2539dae6ad8fSAl Viro path_put(&nd.path); 2540ed75e95dSAl Viro return dentry; 2541dae6ad8fSAl Viro } 2542dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2543dae6ad8fSAl Viro 2544dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2545dae6ad8fSAl Viro { 2546dae6ad8fSAl Viro char *tmp = getname(pathname); 2547dae6ad8fSAl Viro struct dentry *res; 2548dae6ad8fSAl Viro if (IS_ERR(tmp)) 2549dae6ad8fSAl Viro return ERR_CAST(tmp); 2550dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2551dae6ad8fSAl Viro putname(tmp); 2552dae6ad8fSAl Viro return res; 2553dae6ad8fSAl Viro } 2554dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2555dae6ad8fSAl Viro 25561a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 25571da177e4SLinus Torvalds { 2558a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds if (error) 25611da177e4SLinus Torvalds return error; 25621da177e4SLinus Torvalds 2563e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2564e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 25651da177e4SLinus Torvalds return -EPERM; 25661da177e4SLinus Torvalds 2567acfa4380SAl Viro if (!dir->i_op->mknod) 25681da177e4SLinus Torvalds return -EPERM; 25691da177e4SLinus Torvalds 257008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 257108ce5f16SSerge E. Hallyn if (error) 257208ce5f16SSerge E. Hallyn return error; 257308ce5f16SSerge E. Hallyn 25741da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 25751da177e4SLinus Torvalds if (error) 25761da177e4SLinus Torvalds return error; 25771da177e4SLinus Torvalds 25781da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2579a74574aaSStephen Smalley if (!error) 2580f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25811da177e4SLinus Torvalds return error; 25821da177e4SLinus Torvalds } 25831da177e4SLinus Torvalds 2584f69aac00SAl Viro static int may_mknod(umode_t mode) 2585463c3197SDave Hansen { 2586463c3197SDave Hansen switch (mode & S_IFMT) { 2587463c3197SDave Hansen case S_IFREG: 2588463c3197SDave Hansen case S_IFCHR: 2589463c3197SDave Hansen case S_IFBLK: 2590463c3197SDave Hansen case S_IFIFO: 2591463c3197SDave Hansen case S_IFSOCK: 2592463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2593463c3197SDave Hansen return 0; 2594463c3197SDave Hansen case S_IFDIR: 2595463c3197SDave Hansen return -EPERM; 2596463c3197SDave Hansen default: 2597463c3197SDave Hansen return -EINVAL; 2598463c3197SDave Hansen } 2599463c3197SDave Hansen } 2600463c3197SDave Hansen 26018208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 26022e4d0924SHeiko Carstens unsigned, dev) 26031da177e4SLinus Torvalds { 26041da177e4SLinus Torvalds struct dentry *dentry; 2605dae6ad8fSAl Viro struct path path; 2606dae6ad8fSAl Viro int error; 26071da177e4SLinus Torvalds 26081da177e4SLinus Torvalds if (S_ISDIR(mode)) 26091da177e4SLinus Torvalds return -EPERM; 26101da177e4SLinus Torvalds 2611dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2612dae6ad8fSAl Viro if (IS_ERR(dentry)) 2613dae6ad8fSAl Viro return PTR_ERR(dentry); 26142ad94ae6SAl Viro 2615dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2616ce3b0f8dSAl Viro mode &= ~current_umask(); 2617463c3197SDave Hansen error = may_mknod(mode); 2618463c3197SDave Hansen if (error) 2619463c3197SDave Hansen goto out_dput; 2620dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2621463c3197SDave Hansen if (error) 2622463c3197SDave Hansen goto out_dput; 2623dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2624be6d3e56SKentaro Takeda if (error) 2625be6d3e56SKentaro Takeda goto out_drop_write; 26261da177e4SLinus Torvalds switch (mode & S_IFMT) { 26271da177e4SLinus Torvalds case 0: case S_IFREG: 2628dae6ad8fSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); 26291da177e4SLinus Torvalds break; 26301da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2631dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 26321da177e4SLinus Torvalds new_decode_dev(dev)); 26331da177e4SLinus Torvalds break; 26341da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2635dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 26361da177e4SLinus Torvalds break; 26371da177e4SLinus Torvalds } 2638be6d3e56SKentaro Takeda out_drop_write: 2639dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2640463c3197SDave Hansen out_dput: 26411da177e4SLinus Torvalds dput(dentry); 2642dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2643dae6ad8fSAl Viro path_put(&path); 26441da177e4SLinus Torvalds 26451da177e4SLinus Torvalds return error; 26461da177e4SLinus Torvalds } 26471da177e4SLinus Torvalds 26488208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 26495590ff0dSUlrich Drepper { 26505590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 26515590ff0dSUlrich Drepper } 26525590ff0dSUlrich Drepper 265318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 26541da177e4SLinus Torvalds { 2655a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26568de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds if (error) 26591da177e4SLinus Torvalds return error; 26601da177e4SLinus Torvalds 2661acfa4380SAl Viro if (!dir->i_op->mkdir) 26621da177e4SLinus Torvalds return -EPERM; 26631da177e4SLinus Torvalds 26641da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 26651da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 26661da177e4SLinus Torvalds if (error) 26671da177e4SLinus Torvalds return error; 26681da177e4SLinus Torvalds 26698de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 26708de52778SAl Viro return -EMLINK; 26718de52778SAl Viro 26721da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2673a74574aaSStephen Smalley if (!error) 2674f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 26751da177e4SLinus Torvalds return error; 26761da177e4SLinus Torvalds } 26771da177e4SLinus Torvalds 2678a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 26791da177e4SLinus Torvalds { 26806902d925SDave Hansen struct dentry *dentry; 2681dae6ad8fSAl Viro struct path path; 2682dae6ad8fSAl Viro int error; 26831da177e4SLinus Torvalds 2684dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 26856902d925SDave Hansen if (IS_ERR(dentry)) 2686dae6ad8fSAl Viro return PTR_ERR(dentry); 26876902d925SDave Hansen 2688dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2689ce3b0f8dSAl Viro mode &= ~current_umask(); 2690dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2691463c3197SDave Hansen if (error) 2692463c3197SDave Hansen goto out_dput; 2693dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 2694be6d3e56SKentaro Takeda if (error) 2695be6d3e56SKentaro Takeda goto out_drop_write; 2696dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 2697be6d3e56SKentaro Takeda out_drop_write: 2698dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2699463c3197SDave Hansen out_dput: 27001da177e4SLinus Torvalds dput(dentry); 2701dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2702dae6ad8fSAl Viro path_put(&path); 27031da177e4SLinus Torvalds return error; 27041da177e4SLinus Torvalds } 27051da177e4SLinus Torvalds 2706a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 27075590ff0dSUlrich Drepper { 27085590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 27095590ff0dSUlrich Drepper } 27105590ff0dSUlrich Drepper 27111da177e4SLinus Torvalds /* 2712a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2713a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2714a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2715a71905f0SSage Weil * then we drop the dentry now. 27161da177e4SLinus Torvalds * 27171da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 27181da177e4SLinus Torvalds * do a 27191da177e4SLinus Torvalds * 27201da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 27211da177e4SLinus Torvalds * return -EBUSY; 27221da177e4SLinus Torvalds * 27231da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 27241da177e4SLinus Torvalds * that is still in use by something else.. 27251da177e4SLinus Torvalds */ 27261da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 27271da177e4SLinus Torvalds { 27281da177e4SLinus Torvalds shrink_dcache_parent(dentry); 27291da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 273064252c75SSage Weil if (dentry->d_count == 1) 27311da177e4SLinus Torvalds __d_drop(dentry); 27321da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 27331da177e4SLinus Torvalds } 27341da177e4SLinus Torvalds 27351da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 27361da177e4SLinus Torvalds { 27371da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 27381da177e4SLinus Torvalds 27391da177e4SLinus Torvalds if (error) 27401da177e4SLinus Torvalds return error; 27411da177e4SLinus Torvalds 2742acfa4380SAl Viro if (!dir->i_op->rmdir) 27431da177e4SLinus Torvalds return -EPERM; 27441da177e4SLinus Torvalds 27451d2ef590SAl Viro dget(dentry); 27461b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2747912dbc15SSage Weil 27481da177e4SLinus Torvalds error = -EBUSY; 2749912dbc15SSage Weil if (d_mountpoint(dentry)) 2750912dbc15SSage Weil goto out; 2751912dbc15SSage Weil 27521da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2753912dbc15SSage Weil if (error) 2754912dbc15SSage Weil goto out; 2755912dbc15SSage Weil 27563cebde24SSage Weil shrink_dcache_parent(dentry); 27571da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2758912dbc15SSage Weil if (error) 2759912dbc15SSage Weil goto out; 2760912dbc15SSage Weil 27611da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2762d83c49f3SAl Viro dont_mount(dentry); 27631da177e4SLinus Torvalds 2764912dbc15SSage Weil out: 2765912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 27661d2ef590SAl Viro dput(dentry); 2767912dbc15SSage Weil if (!error) 2768912dbc15SSage Weil d_delete(dentry); 27691da177e4SLinus Torvalds return error; 27701da177e4SLinus Torvalds } 27711da177e4SLinus Torvalds 27725590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 27731da177e4SLinus Torvalds { 27741da177e4SLinus Torvalds int error = 0; 27751da177e4SLinus Torvalds char * name; 27761da177e4SLinus Torvalds struct dentry *dentry; 27771da177e4SLinus Torvalds struct nameidata nd; 27781da177e4SLinus Torvalds 27792ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27801da177e4SLinus Torvalds if (error) 27812ad94ae6SAl Viro return error; 27821da177e4SLinus Torvalds 27831da177e4SLinus Torvalds switch(nd.last_type) { 27841da177e4SLinus Torvalds case LAST_DOTDOT: 27851da177e4SLinus Torvalds error = -ENOTEMPTY; 27861da177e4SLinus Torvalds goto exit1; 27871da177e4SLinus Torvalds case LAST_DOT: 27881da177e4SLinus Torvalds error = -EINVAL; 27891da177e4SLinus Torvalds goto exit1; 27901da177e4SLinus Torvalds case LAST_ROOT: 27911da177e4SLinus Torvalds error = -EBUSY; 27921da177e4SLinus Torvalds goto exit1; 27931da177e4SLinus Torvalds } 27940612d9fbSOGAWA Hirofumi 27950612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27960612d9fbSOGAWA Hirofumi 27974ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 279849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27991da177e4SLinus Torvalds error = PTR_ERR(dentry); 28006902d925SDave Hansen if (IS_ERR(dentry)) 28016902d925SDave Hansen goto exit2; 2802e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2803e6bc45d6STheodore Ts'o error = -ENOENT; 2804e6bc45d6STheodore Ts'o goto exit3; 2805e6bc45d6STheodore Ts'o } 28060622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 28070622753bSDave Hansen if (error) 28080622753bSDave Hansen goto exit3; 2809be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2810be6d3e56SKentaro Takeda if (error) 2811be6d3e56SKentaro Takeda goto exit4; 28124ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2813be6d3e56SKentaro Takeda exit4: 28140622753bSDave Hansen mnt_drop_write(nd.path.mnt); 28150622753bSDave Hansen exit3: 28161da177e4SLinus Torvalds dput(dentry); 28176902d925SDave Hansen exit2: 28184ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28191da177e4SLinus Torvalds exit1: 28201d957f9bSJan Blunck path_put(&nd.path); 28211da177e4SLinus Torvalds putname(name); 28221da177e4SLinus Torvalds return error; 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds 28253cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 28265590ff0dSUlrich Drepper { 28275590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 28285590ff0dSUlrich Drepper } 28295590ff0dSUlrich Drepper 28301da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 28311da177e4SLinus Torvalds { 28321da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 28331da177e4SLinus Torvalds 28341da177e4SLinus Torvalds if (error) 28351da177e4SLinus Torvalds return error; 28361da177e4SLinus Torvalds 2837acfa4380SAl Viro if (!dir->i_op->unlink) 28381da177e4SLinus Torvalds return -EPERM; 28391da177e4SLinus Torvalds 28401b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 28411da177e4SLinus Torvalds if (d_mountpoint(dentry)) 28421da177e4SLinus Torvalds error = -EBUSY; 28431da177e4SLinus Torvalds else { 28441da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2845bec1052eSAl Viro if (!error) { 28461da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2847bec1052eSAl Viro if (!error) 2848d83c49f3SAl Viro dont_mount(dentry); 2849bec1052eSAl Viro } 28501da177e4SLinus Torvalds } 28511b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 28521da177e4SLinus Torvalds 28531da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 28541da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2855ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 28561da177e4SLinus Torvalds d_delete(dentry); 28571da177e4SLinus Torvalds } 28580eeca283SRobert Love 28591da177e4SLinus Torvalds return error; 28601da177e4SLinus Torvalds } 28611da177e4SLinus Torvalds 28621da177e4SLinus Torvalds /* 28631da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 28641b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 28651da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 28661da177e4SLinus Torvalds * while waiting on the I/O. 28671da177e4SLinus Torvalds */ 28685590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 28691da177e4SLinus Torvalds { 28702ad94ae6SAl Viro int error; 28711da177e4SLinus Torvalds char *name; 28721da177e4SLinus Torvalds struct dentry *dentry; 28731da177e4SLinus Torvalds struct nameidata nd; 28741da177e4SLinus Torvalds struct inode *inode = NULL; 28751da177e4SLinus Torvalds 28762ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 28771da177e4SLinus Torvalds if (error) 28782ad94ae6SAl Viro return error; 28792ad94ae6SAl Viro 28801da177e4SLinus Torvalds error = -EISDIR; 28811da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 28821da177e4SLinus Torvalds goto exit1; 28830612d9fbSOGAWA Hirofumi 28840612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 28850612d9fbSOGAWA Hirofumi 28864ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 288749705b77SChristoph Hellwig dentry = lookup_hash(&nd); 28881da177e4SLinus Torvalds error = PTR_ERR(dentry); 28891da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 28901da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 289150338b88STörök Edwin if (nd.last.name[nd.last.len]) 289250338b88STörök Edwin goto slashes; 28931da177e4SLinus Torvalds inode = dentry->d_inode; 289450338b88STörök Edwin if (!inode) 2895e6bc45d6STheodore Ts'o goto slashes; 28967de9c6eeSAl Viro ihold(inode); 28970622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 28980622753bSDave Hansen if (error) 28990622753bSDave Hansen goto exit2; 2900be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2901be6d3e56SKentaro Takeda if (error) 2902be6d3e56SKentaro Takeda goto exit3; 29034ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2904be6d3e56SKentaro Takeda exit3: 29050622753bSDave Hansen mnt_drop_write(nd.path.mnt); 29061da177e4SLinus Torvalds exit2: 29071da177e4SLinus Torvalds dput(dentry); 29081da177e4SLinus Torvalds } 29094ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29101da177e4SLinus Torvalds if (inode) 29111da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 29121da177e4SLinus Torvalds exit1: 29131d957f9bSJan Blunck path_put(&nd.path); 29141da177e4SLinus Torvalds putname(name); 29151da177e4SLinus Torvalds return error; 29161da177e4SLinus Torvalds 29171da177e4SLinus Torvalds slashes: 29181da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 29191da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 29201da177e4SLinus Torvalds goto exit2; 29211da177e4SLinus Torvalds } 29221da177e4SLinus Torvalds 29232e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 29245590ff0dSUlrich Drepper { 29255590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 29265590ff0dSUlrich Drepper return -EINVAL; 29275590ff0dSUlrich Drepper 29285590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 29295590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 29305590ff0dSUlrich Drepper 29315590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 29325590ff0dSUlrich Drepper } 29335590ff0dSUlrich Drepper 29343480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 29355590ff0dSUlrich Drepper { 29365590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 29375590ff0dSUlrich Drepper } 29385590ff0dSUlrich Drepper 2939db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 29401da177e4SLinus Torvalds { 2941a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 29421da177e4SLinus Torvalds 29431da177e4SLinus Torvalds if (error) 29441da177e4SLinus Torvalds return error; 29451da177e4SLinus Torvalds 2946acfa4380SAl Viro if (!dir->i_op->symlink) 29471da177e4SLinus Torvalds return -EPERM; 29481da177e4SLinus Torvalds 29491da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 29501da177e4SLinus Torvalds if (error) 29511da177e4SLinus Torvalds return error; 29521da177e4SLinus Torvalds 29531da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2954a74574aaSStephen Smalley if (!error) 2955f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29561da177e4SLinus Torvalds return error; 29571da177e4SLinus Torvalds } 29581da177e4SLinus Torvalds 29592e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 29602e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 29611da177e4SLinus Torvalds { 29622ad94ae6SAl Viro int error; 29631da177e4SLinus Torvalds char *from; 29646902d925SDave Hansen struct dentry *dentry; 2965dae6ad8fSAl Viro struct path path; 29661da177e4SLinus Torvalds 29671da177e4SLinus Torvalds from = getname(oldname); 29681da177e4SLinus Torvalds if (IS_ERR(from)) 29691da177e4SLinus Torvalds return PTR_ERR(from); 29702ad94ae6SAl Viro 2971dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 29721da177e4SLinus Torvalds error = PTR_ERR(dentry); 29736902d925SDave Hansen if (IS_ERR(dentry)) 2974dae6ad8fSAl Viro goto out_putname; 29756902d925SDave Hansen 2976dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 297775c3f29dSDave Hansen if (error) 297875c3f29dSDave Hansen goto out_dput; 2979dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 2980be6d3e56SKentaro Takeda if (error) 2981be6d3e56SKentaro Takeda goto out_drop_write; 2982dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 2983be6d3e56SKentaro Takeda out_drop_write: 2984dae6ad8fSAl Viro mnt_drop_write(path.mnt); 298575c3f29dSDave Hansen out_dput: 29861da177e4SLinus Torvalds dput(dentry); 2987dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2988dae6ad8fSAl Viro path_put(&path); 29896902d925SDave Hansen out_putname: 29901da177e4SLinus Torvalds putname(from); 29911da177e4SLinus Torvalds return error; 29921da177e4SLinus Torvalds } 29931da177e4SLinus Torvalds 29943480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 29955590ff0dSUlrich Drepper { 29965590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 29975590ff0dSUlrich Drepper } 29985590ff0dSUlrich Drepper 29991da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 30001da177e4SLinus Torvalds { 30011da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 30028de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 30031da177e4SLinus Torvalds int error; 30041da177e4SLinus Torvalds 30051da177e4SLinus Torvalds if (!inode) 30061da177e4SLinus Torvalds return -ENOENT; 30071da177e4SLinus Torvalds 3008a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 30091da177e4SLinus Torvalds if (error) 30101da177e4SLinus Torvalds return error; 30111da177e4SLinus Torvalds 30121da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 30131da177e4SLinus Torvalds return -EXDEV; 30141da177e4SLinus Torvalds 30151da177e4SLinus Torvalds /* 30161da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 30171da177e4SLinus Torvalds */ 30181da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 30191da177e4SLinus Torvalds return -EPERM; 3020acfa4380SAl Viro if (!dir->i_op->link) 30211da177e4SLinus Torvalds return -EPERM; 30227e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 30231da177e4SLinus Torvalds return -EPERM; 30241da177e4SLinus Torvalds 30251da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 30261da177e4SLinus Torvalds if (error) 30271da177e4SLinus Torvalds return error; 30281da177e4SLinus Torvalds 30297e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3030aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3031aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3032aae8a97dSAneesh Kumar K.V error = -ENOENT; 30338de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 30348de52778SAl Viro error = -EMLINK; 3035aae8a97dSAneesh Kumar K.V else 30361da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 30377e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3038e31e14ecSStephen Smalley if (!error) 30397e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 30401da177e4SLinus Torvalds return error; 30411da177e4SLinus Torvalds } 30421da177e4SLinus Torvalds 30431da177e4SLinus Torvalds /* 30441da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 30451da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 30461da177e4SLinus Torvalds * newname. --KAB 30471da177e4SLinus Torvalds * 30481da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 30491da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 30501da177e4SLinus Torvalds * and other special files. --ADM 30511da177e4SLinus Torvalds */ 30522e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 30532e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 30541da177e4SLinus Torvalds { 30551da177e4SLinus Torvalds struct dentry *new_dentry; 3056dae6ad8fSAl Viro struct path old_path, new_path; 305711a7b371SAneesh Kumar K.V int how = 0; 30581da177e4SLinus Torvalds int error; 30591da177e4SLinus Torvalds 306011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3061c04030e1SUlrich Drepper return -EINVAL; 306211a7b371SAneesh Kumar K.V /* 306311a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 306411a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 306511a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 306611a7b371SAneesh Kumar K.V */ 306711a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 306811a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 306911a7b371SAneesh Kumar K.V return -ENOENT; 307011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 307111a7b371SAneesh Kumar K.V } 3072c04030e1SUlrich Drepper 307311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 307411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 307511a7b371SAneesh Kumar K.V 307611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 30771da177e4SLinus Torvalds if (error) 30782ad94ae6SAl Viro return error; 30792ad94ae6SAl Viro 3080dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 30811da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 30826902d925SDave Hansen if (IS_ERR(new_dentry)) 3083dae6ad8fSAl Viro goto out; 3084dae6ad8fSAl Viro 3085dae6ad8fSAl Viro error = -EXDEV; 3086dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3087dae6ad8fSAl Viro goto out_dput; 3088dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 308975c3f29dSDave Hansen if (error) 309075c3f29dSDave Hansen goto out_dput; 3091dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3092be6d3e56SKentaro Takeda if (error) 3093be6d3e56SKentaro Takeda goto out_drop_write; 3094dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 3095be6d3e56SKentaro Takeda out_drop_write: 3096dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 309775c3f29dSDave Hansen out_dput: 30981da177e4SLinus Torvalds dput(new_dentry); 3099dae6ad8fSAl Viro mutex_unlock(&new_path.dentry->d_inode->i_mutex); 3100dae6ad8fSAl Viro path_put(&new_path); 31011da177e4SLinus Torvalds out: 31022d8f3038SAl Viro path_put(&old_path); 31031da177e4SLinus Torvalds 31041da177e4SLinus Torvalds return error; 31051da177e4SLinus Torvalds } 31061da177e4SLinus Torvalds 31073480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 31085590ff0dSUlrich Drepper { 3109c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 31105590ff0dSUlrich Drepper } 31115590ff0dSUlrich Drepper 31121da177e4SLinus Torvalds /* 31131da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 31141da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 31151da177e4SLinus Torvalds * Problems: 31161da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 31171da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 31181da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3119a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 31201da177e4SLinus Torvalds * story. 31211da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 31221b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 31231da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 31241da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3125a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 31261da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 31271da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 31281da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3129a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 31301da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 31311da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 31321da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3133e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 31341b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 31351da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3136c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 31371da177e4SLinus Torvalds * locking]. 31381da177e4SLinus Torvalds */ 313975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 31401da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31411da177e4SLinus Torvalds { 31421da177e4SLinus Torvalds int error = 0; 31439055cba7SSage Weil struct inode *target = new_dentry->d_inode; 31448de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 31451da177e4SLinus Torvalds 31461da177e4SLinus Torvalds /* 31471da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 31481da177e4SLinus Torvalds * we'll need to flip '..'. 31491da177e4SLinus Torvalds */ 31501da177e4SLinus Torvalds if (new_dir != old_dir) { 3151f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 31521da177e4SLinus Torvalds if (error) 31531da177e4SLinus Torvalds return error; 31541da177e4SLinus Torvalds } 31551da177e4SLinus Torvalds 31561da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 31571da177e4SLinus Torvalds if (error) 31581da177e4SLinus Torvalds return error; 31591da177e4SLinus Torvalds 31601d2ef590SAl Viro dget(new_dentry); 3161d83c49f3SAl Viro if (target) 31621b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 31639055cba7SSage Weil 31641da177e4SLinus Torvalds error = -EBUSY; 31659055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 31669055cba7SSage Weil goto out; 31679055cba7SSage Weil 31688de52778SAl Viro error = -EMLINK; 31698de52778SAl Viro if (max_links && !target && new_dir != old_dir && 31708de52778SAl Viro new_dir->i_nlink >= max_links) 31718de52778SAl Viro goto out; 31728de52778SAl Viro 31733cebde24SSage Weil if (target) 31743cebde24SSage Weil shrink_dcache_parent(new_dentry); 31751da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 31769055cba7SSage Weil if (error) 31779055cba7SSage Weil goto out; 31789055cba7SSage Weil 31791da177e4SLinus Torvalds if (target) { 31801da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3181d83c49f3SAl Viro dont_mount(new_dentry); 3182d83c49f3SAl Viro } 31839055cba7SSage Weil out: 31849055cba7SSage Weil if (target) 31851b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 31861d2ef590SAl Viro dput(new_dentry); 3187e31e14ecSStephen Smalley if (!error) 3188349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 31891da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 31901da177e4SLinus Torvalds return error; 31911da177e4SLinus Torvalds } 31921da177e4SLinus Torvalds 319375c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 31941da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31951da177e4SLinus Torvalds { 319651892bbbSSage Weil struct inode *target = new_dentry->d_inode; 31971da177e4SLinus Torvalds int error; 31981da177e4SLinus Torvalds 31991da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 32001da177e4SLinus Torvalds if (error) 32011da177e4SLinus Torvalds return error; 32021da177e4SLinus Torvalds 32031da177e4SLinus Torvalds dget(new_dentry); 32041da177e4SLinus Torvalds if (target) 32051b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 320651892bbbSSage Weil 32071da177e4SLinus Torvalds error = -EBUSY; 320851892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 320951892bbbSSage Weil goto out; 321051892bbbSSage Weil 32111da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 321251892bbbSSage Weil if (error) 321351892bbbSSage Weil goto out; 321451892bbbSSage Weil 3215bec1052eSAl Viro if (target) 3216d83c49f3SAl Viro dont_mount(new_dentry); 3217349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 32181da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 321951892bbbSSage Weil out: 32201da177e4SLinus Torvalds if (target) 32211b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 32221da177e4SLinus Torvalds dput(new_dentry); 32231da177e4SLinus Torvalds return error; 32241da177e4SLinus Torvalds } 32251da177e4SLinus Torvalds 32261da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 32271da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32281da177e4SLinus Torvalds { 32291da177e4SLinus Torvalds int error; 32301da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 323159b0df21SEric Paris const unsigned char *old_name; 32321da177e4SLinus Torvalds 32331da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 32341da177e4SLinus Torvalds return 0; 32351da177e4SLinus Torvalds 32361da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 32371da177e4SLinus Torvalds if (error) 32381da177e4SLinus Torvalds return error; 32391da177e4SLinus Torvalds 32401da177e4SLinus Torvalds if (!new_dentry->d_inode) 3241a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 32421da177e4SLinus Torvalds else 32431da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 32441da177e4SLinus Torvalds if (error) 32451da177e4SLinus Torvalds return error; 32461da177e4SLinus Torvalds 3247acfa4380SAl Viro if (!old_dir->i_op->rename) 32481da177e4SLinus Torvalds return -EPERM; 32491da177e4SLinus Torvalds 32500eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 32510eeca283SRobert Love 32521da177e4SLinus Torvalds if (is_dir) 32531da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 32541da177e4SLinus Torvalds else 32551da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3256123df294SAl Viro if (!error) 3257123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 32585a190ae6SAl Viro new_dentry->d_inode, old_dentry); 32590eeca283SRobert Love fsnotify_oldname_free(old_name); 32600eeca283SRobert Love 32611da177e4SLinus Torvalds return error; 32621da177e4SLinus Torvalds } 32631da177e4SLinus Torvalds 32642e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 32652e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 32661da177e4SLinus Torvalds { 32671da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 32681da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 32691da177e4SLinus Torvalds struct dentry *trap; 32701da177e4SLinus Torvalds struct nameidata oldnd, newnd; 32712ad94ae6SAl Viro char *from; 32722ad94ae6SAl Viro char *to; 32732ad94ae6SAl Viro int error; 32741da177e4SLinus Torvalds 32752ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 32761da177e4SLinus Torvalds if (error) 32771da177e4SLinus Torvalds goto exit; 32781da177e4SLinus Torvalds 32792ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 32801da177e4SLinus Torvalds if (error) 32811da177e4SLinus Torvalds goto exit1; 32821da177e4SLinus Torvalds 32831da177e4SLinus Torvalds error = -EXDEV; 32844ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 32851da177e4SLinus Torvalds goto exit2; 32861da177e4SLinus Torvalds 32874ac91378SJan Blunck old_dir = oldnd.path.dentry; 32881da177e4SLinus Torvalds error = -EBUSY; 32891da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 32901da177e4SLinus Torvalds goto exit2; 32911da177e4SLinus Torvalds 32924ac91378SJan Blunck new_dir = newnd.path.dentry; 32931da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 32941da177e4SLinus Torvalds goto exit2; 32951da177e4SLinus Torvalds 32960612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 32970612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 32984e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 32990612d9fbSOGAWA Hirofumi 33001da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 33011da177e4SLinus Torvalds 330249705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 33031da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 33041da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 33051da177e4SLinus Torvalds goto exit3; 33061da177e4SLinus Torvalds /* source must exist */ 33071da177e4SLinus Torvalds error = -ENOENT; 33081da177e4SLinus Torvalds if (!old_dentry->d_inode) 33091da177e4SLinus Torvalds goto exit4; 33101da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 33111da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 33121da177e4SLinus Torvalds error = -ENOTDIR; 33131da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 33141da177e4SLinus Torvalds goto exit4; 33151da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 33161da177e4SLinus Torvalds goto exit4; 33171da177e4SLinus Torvalds } 33181da177e4SLinus Torvalds /* source should not be ancestor of target */ 33191da177e4SLinus Torvalds error = -EINVAL; 33201da177e4SLinus Torvalds if (old_dentry == trap) 33211da177e4SLinus Torvalds goto exit4; 332249705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 33231da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 33241da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 33251da177e4SLinus Torvalds goto exit4; 33261da177e4SLinus Torvalds /* target should not be an ancestor of source */ 33271da177e4SLinus Torvalds error = -ENOTEMPTY; 33281da177e4SLinus Torvalds if (new_dentry == trap) 33291da177e4SLinus Torvalds goto exit5; 33301da177e4SLinus Torvalds 33319079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 33329079b1ebSDave Hansen if (error) 33339079b1ebSDave Hansen goto exit5; 3334be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3335be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3336be6d3e56SKentaro Takeda if (error) 3337be6d3e56SKentaro Takeda goto exit6; 33381da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 33391da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3340be6d3e56SKentaro Takeda exit6: 33419079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 33421da177e4SLinus Torvalds exit5: 33431da177e4SLinus Torvalds dput(new_dentry); 33441da177e4SLinus Torvalds exit4: 33451da177e4SLinus Torvalds dput(old_dentry); 33461da177e4SLinus Torvalds exit3: 33471da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 33481da177e4SLinus Torvalds exit2: 33491d957f9bSJan Blunck path_put(&newnd.path); 33502ad94ae6SAl Viro putname(to); 33511da177e4SLinus Torvalds exit1: 33521d957f9bSJan Blunck path_put(&oldnd.path); 33531da177e4SLinus Torvalds putname(from); 33542ad94ae6SAl Viro exit: 33551da177e4SLinus Torvalds return error; 33561da177e4SLinus Torvalds } 33571da177e4SLinus Torvalds 3358a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 33595590ff0dSUlrich Drepper { 33605590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 33615590ff0dSUlrich Drepper } 33625590ff0dSUlrich Drepper 33631da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 33641da177e4SLinus Torvalds { 33651da177e4SLinus Torvalds int len; 33661da177e4SLinus Torvalds 33671da177e4SLinus Torvalds len = PTR_ERR(link); 33681da177e4SLinus Torvalds if (IS_ERR(link)) 33691da177e4SLinus Torvalds goto out; 33701da177e4SLinus Torvalds 33711da177e4SLinus Torvalds len = strlen(link); 33721da177e4SLinus Torvalds if (len > (unsigned) buflen) 33731da177e4SLinus Torvalds len = buflen; 33741da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 33751da177e4SLinus Torvalds len = -EFAULT; 33761da177e4SLinus Torvalds out: 33771da177e4SLinus Torvalds return len; 33781da177e4SLinus Torvalds } 33791da177e4SLinus Torvalds 33801da177e4SLinus Torvalds /* 33811da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 33821da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 33831da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 33841da177e4SLinus Torvalds */ 33851da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 33861da177e4SLinus Torvalds { 33871da177e4SLinus Torvalds struct nameidata nd; 3388cc314eefSLinus Torvalds void *cookie; 3389694a1764SMarcin Slusarz int res; 3390cc314eefSLinus Torvalds 33911da177e4SLinus Torvalds nd.depth = 0; 3392cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3393694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3394694a1764SMarcin Slusarz return PTR_ERR(cookie); 3395694a1764SMarcin Slusarz 3396694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 33971da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3398cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3399694a1764SMarcin Slusarz return res; 34001da177e4SLinus Torvalds } 34011da177e4SLinus Torvalds 34021da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 34031da177e4SLinus Torvalds { 34041da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 34051da177e4SLinus Torvalds } 34061da177e4SLinus Torvalds 34071da177e4SLinus Torvalds /* get the link contents into pagecache */ 34081da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 34091da177e4SLinus Torvalds { 3410ebd09abbSDuane Griffin char *kaddr; 34111da177e4SLinus Torvalds struct page *page; 34121da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3413090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 34141da177e4SLinus Torvalds if (IS_ERR(page)) 34156fe6900eSNick Piggin return (char*)page; 34161da177e4SLinus Torvalds *ppage = page; 3417ebd09abbSDuane Griffin kaddr = kmap(page); 3418ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3419ebd09abbSDuane Griffin return kaddr; 34201da177e4SLinus Torvalds } 34211da177e4SLinus Torvalds 34221da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 34231da177e4SLinus Torvalds { 34241da177e4SLinus Torvalds struct page *page = NULL; 34251da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 34261da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 34271da177e4SLinus Torvalds if (page) { 34281da177e4SLinus Torvalds kunmap(page); 34291da177e4SLinus Torvalds page_cache_release(page); 34301da177e4SLinus Torvalds } 34311da177e4SLinus Torvalds return res; 34321da177e4SLinus Torvalds } 34331da177e4SLinus Torvalds 3434cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 34351da177e4SLinus Torvalds { 3436cc314eefSLinus Torvalds struct page *page = NULL; 34371da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3438cc314eefSLinus Torvalds return page; 34391da177e4SLinus Torvalds } 34401da177e4SLinus Torvalds 3441cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 34421da177e4SLinus Torvalds { 3443cc314eefSLinus Torvalds struct page *page = cookie; 3444cc314eefSLinus Torvalds 3445cc314eefSLinus Torvalds if (page) { 34461da177e4SLinus Torvalds kunmap(page); 34471da177e4SLinus Torvalds page_cache_release(page); 34481da177e4SLinus Torvalds } 34491da177e4SLinus Torvalds } 34501da177e4SLinus Torvalds 345154566b2cSNick Piggin /* 345254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 345354566b2cSNick Piggin */ 345454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 34551da177e4SLinus Torvalds { 34561da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 34570adb25d2SKirill Korotaev struct page *page; 3458afddba49SNick Piggin void *fsdata; 3459beb497abSDmitriy Monakhov int err; 34601da177e4SLinus Torvalds char *kaddr; 346154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 346254566b2cSNick Piggin if (nofs) 346354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 34641da177e4SLinus Torvalds 34657e53cac4SNeilBrown retry: 3466afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 346754566b2cSNick Piggin flags, &page, &fsdata); 34681da177e4SLinus Torvalds if (err) 3469afddba49SNick Piggin goto fail; 3470afddba49SNick Piggin 3471e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 34721da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3473e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3474afddba49SNick Piggin 3475afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3476afddba49SNick Piggin page, fsdata); 34771da177e4SLinus Torvalds if (err < 0) 34781da177e4SLinus Torvalds goto fail; 3479afddba49SNick Piggin if (err < len-1) 3480afddba49SNick Piggin goto retry; 3481afddba49SNick Piggin 34821da177e4SLinus Torvalds mark_inode_dirty(inode); 34831da177e4SLinus Torvalds return 0; 34841da177e4SLinus Torvalds fail: 34851da177e4SLinus Torvalds return err; 34861da177e4SLinus Torvalds } 34871da177e4SLinus Torvalds 34880adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 34890adb25d2SKirill Korotaev { 34900adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 349154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 34920adb25d2SKirill Korotaev } 34930adb25d2SKirill Korotaev 349492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 34951da177e4SLinus Torvalds .readlink = generic_readlink, 34961da177e4SLinus Torvalds .follow_link = page_follow_link_light, 34971da177e4SLinus Torvalds .put_link = page_put_link, 34981da177e4SLinus Torvalds }; 34991da177e4SLinus Torvalds 35002d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3501cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 35021da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 35031da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 35041da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 35051da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 35061da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 35071da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 35081da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 35091da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 35101da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 35110adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 35121da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 35131da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3514d1811465SAl Viro EXPORT_SYMBOL(kern_path); 351516f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3516f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 35171da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 35181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 35191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 35201da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 35211da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 35221da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 35231da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 35241da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 35251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 35261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 35271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 35281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 35291da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 35301da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3531