11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/pagemap.h> 230eeca283SRobert Love #include <linux/fsnotify.h> 241da177e4SLinus Torvalds #include <linux/personality.h> 251da177e4SLinus Torvalds #include <linux/security.h> 266146f0d5SMimi Zohar #include <linux/ima.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 345ad4e53bSAl Viro #include <linux/fs_struct.h> 35e77819e5SLinus Torvalds #include <linux/posix_acl.h> 361da177e4SLinus Torvalds #include <asm/uaccess.h> 371da177e4SLinus Torvalds 38e81e3f4dSEric Paris #include "internal.h" 39c7105365SAl Viro #include "mount.h" 40e81e3f4dSEric Paris 411da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 421da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 431da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 441da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 451da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 461da177e4SLinus Torvalds * 471da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 481da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 491da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 501da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 511da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 521da177e4SLinus Torvalds * the special cases of the former code. 531da177e4SLinus Torvalds * 541da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 551da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 561da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 591da177e4SLinus Torvalds * resolution to correspond with current state of the code. 601da177e4SLinus Torvalds * 611da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 621da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 631da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 641da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 651da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 661da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 671da177e4SLinus Torvalds */ 681da177e4SLinus Torvalds 691da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 701da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 711da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 721da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 731da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 741da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7525985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 761da177e4SLinus Torvalds * 771da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 781da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 791da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 801da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 811da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 821da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 831da177e4SLinus Torvalds * and in the old Linux semantics. 841da177e4SLinus Torvalds */ 851da177e4SLinus Torvalds 861da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 871da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 881da177e4SLinus Torvalds * 891da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 901da177e4SLinus Torvalds */ 911da177e4SLinus Torvalds 921da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 931da177e4SLinus Torvalds * inside the path - always follow. 941da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 951da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 961da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 971da177e4SLinus Torvalds * otherwise - don't follow. 981da177e4SLinus Torvalds * (applied in that order). 991da177e4SLinus Torvalds * 1001da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1011da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1021da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1031da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1041da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1051da177e4SLinus Torvalds */ 1061da177e4SLinus Torvalds /* 1071da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 108a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1091da177e4SLinus Torvalds * any extra contention... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds 1121da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1131da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1141da177e4SLinus Torvalds * kernel data space before using them.. 1151da177e4SLinus Torvalds * 1161da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1171da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1181da177e4SLinus Torvalds */ 119858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds int retval; 1221da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1231da177e4SLinus Torvalds 1241da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1251da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1261da177e4SLinus Torvalds return -EFAULT; 1271da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1281da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1321da177e4SLinus Torvalds if (retval > 0) { 1331da177e4SLinus Torvalds if (retval < len) 1341da177e4SLinus Torvalds return 0; 1351da177e4SLinus Torvalds return -ENAMETOOLONG; 1361da177e4SLinus Torvalds } else if (!retval) 1371da177e4SLinus Torvalds retval = -ENOENT; 1381da177e4SLinus Torvalds return retval; 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411fa1e7f6SAndy Whitcroft static char *getname_flags(const char __user *filename, int flags, int *empty) 1421da177e4SLinus Torvalds { 1434043cde8SEric Paris char *result = __getname(); 1444043cde8SEric Paris int retval; 1451da177e4SLinus Torvalds 1464043cde8SEric Paris if (!result) 1474043cde8SEric Paris return ERR_PTR(-ENOMEM); 1481da177e4SLinus Torvalds 1494043cde8SEric Paris retval = do_getname(filename, result); 1501da177e4SLinus Torvalds if (retval < 0) { 1511fa1e7f6SAndy Whitcroft if (retval == -ENOENT && empty) 1521fa1e7f6SAndy Whitcroft *empty = 1; 153f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1544043cde8SEric Paris __putname(result); 1554043cde8SEric Paris return ERR_PTR(retval); 1561da177e4SLinus Torvalds } 157f52e0c11SAl Viro } 1581da177e4SLinus Torvalds audit_getname(result); 1591da177e4SLinus Torvalds return result; 1601da177e4SLinus Torvalds } 1611da177e4SLinus Torvalds 162f52e0c11SAl Viro char *getname(const char __user * filename) 163f52e0c11SAl Viro { 1641fa1e7f6SAndy Whitcroft return getname_flags(filename, 0, 0); 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 6457b9337aaSNick Piggin touch_atime(link->mnt, dentry); 6461da177e4SLinus Torvalds nd_set_link(nd, NULL); 647cd4e91d3SAl Viro 64836f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 64936f3b4f6SAl Viro if (error) { 65036f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 65136f3b4f6SAl Viro path_put(&nd->path); 65236f3b4f6SAl Viro return error; 65336f3b4f6SAl Viro } 65436f3b4f6SAl Viro 65586acdca1SAl Viro nd->last_type = LAST_BIND; 656def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 657def4af30SAl Viro error = PTR_ERR(*p); 658def4af30SAl Viro if (!IS_ERR(*p)) { 6591da177e4SLinus Torvalds char *s = nd_get_link(nd); 660cc314eefSLinus Torvalds error = 0; 6611da177e4SLinus Torvalds if (s) 6621da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 663bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 66416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 665b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 666b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 667bcda7652SAl Viro /* stepped on a _really_ weird one */ 668bcda7652SAl Viro path_put(&nd->path); 669bcda7652SAl Viro error = -ELOOP; 670bcda7652SAl Viro } 671bcda7652SAl Viro } 6721da177e4SLinus Torvalds } 6731da177e4SLinus Torvalds return error; 6741da177e4SLinus Torvalds } 6751da177e4SLinus Torvalds 67631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 67731e6b01fSNick Piggin { 6780714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6790714a533SAl Viro struct mount *parent; 68031e6b01fSNick Piggin struct dentry *mountpoint; 68131e6b01fSNick Piggin 6820714a533SAl Viro parent = mnt->mnt_parent; 6830714a533SAl Viro if (&parent->mnt == path->mnt) 68431e6b01fSNick Piggin return 0; 685a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 68631e6b01fSNick Piggin path->dentry = mountpoint; 6870714a533SAl Viro path->mnt = &parent->mnt; 68831e6b01fSNick Piggin return 1; 68931e6b01fSNick Piggin } 69031e6b01fSNick Piggin 691bab77ebfSAl Viro int follow_up(struct path *path) 6921da177e4SLinus Torvalds { 6930714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6940714a533SAl Viro struct mount *parent; 6951da177e4SLinus Torvalds struct dentry *mountpoint; 69699b7db7bSNick Piggin 69799b7db7bSNick Piggin br_read_lock(vfsmount_lock); 6980714a533SAl Viro parent = mnt->mnt_parent; 6990714a533SAl Viro if (&parent->mnt == path->mnt) { 70099b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 7011da177e4SLinus Torvalds return 0; 7021da177e4SLinus Torvalds } 7030714a533SAl Viro mntget(&parent->mnt); 704a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 70599b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 706bab77ebfSAl Viro dput(path->dentry); 707bab77ebfSAl Viro path->dentry = mountpoint; 708bab77ebfSAl Viro mntput(path->mnt); 7090714a533SAl Viro path->mnt = &parent->mnt; 7101da177e4SLinus Torvalds return 1; 7111da177e4SLinus Torvalds } 7121da177e4SLinus Torvalds 713b5c84bf6SNick Piggin /* 7149875cf80SDavid Howells * Perform an automount 7159875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7169875cf80SDavid Howells * were called with. 7171da177e4SLinus Torvalds */ 7189875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7199875cf80SDavid Howells bool *need_mntput) 72031e6b01fSNick Piggin { 7219875cf80SDavid Howells struct vfsmount *mnt; 722ea5b778aSDavid Howells int err; 7239875cf80SDavid Howells 7249875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7259875cf80SDavid Howells return -EREMOTE; 7269875cf80SDavid Howells 7270ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 7280ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 7290ec26fd0SMiklos Szeredi * the name. 7300ec26fd0SMiklos Szeredi * 7310ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 7325a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 7330ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 7340ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 7350ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 7360ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 7375a30d8a2SDavid Howells */ 7385a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 739d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 7405a30d8a2SDavid Howells path->dentry->d_inode) 7419875cf80SDavid Howells return -EISDIR; 7420ec26fd0SMiklos Szeredi 7439875cf80SDavid Howells current->total_link_count++; 7449875cf80SDavid Howells if (current->total_link_count >= 40) 7459875cf80SDavid Howells return -ELOOP; 7469875cf80SDavid Howells 7479875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7489875cf80SDavid Howells if (IS_ERR(mnt)) { 7499875cf80SDavid Howells /* 7509875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7519875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7529875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7539875cf80SDavid Howells * 7549875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7559875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7569875cf80SDavid Howells * the path is inaccessible and we should say so. 7579875cf80SDavid Howells */ 75849084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 7599875cf80SDavid Howells return -EREMOTE; 7609875cf80SDavid Howells return PTR_ERR(mnt); 76131e6b01fSNick Piggin } 762ea5b778aSDavid Howells 7639875cf80SDavid Howells if (!mnt) /* mount collision */ 7649875cf80SDavid Howells return 0; 7659875cf80SDavid Howells 7668aef1884SAl Viro if (!*need_mntput) { 7678aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7688aef1884SAl Viro mntget(path->mnt); 7698aef1884SAl Viro *need_mntput = true; 7708aef1884SAl Viro } 77119a167afSAl Viro err = finish_automount(mnt, path); 772ea5b778aSDavid Howells 773ea5b778aSDavid Howells switch (err) { 774ea5b778aSDavid Howells case -EBUSY: 775ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 77619a167afSAl Viro return 0; 777ea5b778aSDavid Howells case 0: 7788aef1884SAl Viro path_put(path); 7799875cf80SDavid Howells path->mnt = mnt; 7809875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7819875cf80SDavid Howells return 0; 78219a167afSAl Viro default: 78319a167afSAl Viro return err; 7849875cf80SDavid Howells } 78519a167afSAl Viro 786ea5b778aSDavid Howells } 7879875cf80SDavid Howells 7889875cf80SDavid Howells /* 7899875cf80SDavid Howells * Handle a dentry that is managed in some way. 790cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7919875cf80SDavid Howells * - Flagged as mountpoint 7929875cf80SDavid Howells * - Flagged as automount point 7939875cf80SDavid Howells * 7949875cf80SDavid Howells * This may only be called in refwalk mode. 7959875cf80SDavid Howells * 7969875cf80SDavid Howells * Serialization is taken care of in namespace.c 7979875cf80SDavid Howells */ 7989875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7999875cf80SDavid Howells { 8008aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 8019875cf80SDavid Howells unsigned managed; 8029875cf80SDavid Howells bool need_mntput = false; 8038aef1884SAl Viro int ret = 0; 8049875cf80SDavid Howells 8059875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8069875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8079875cf80SDavid Howells * the components of that value change under us */ 8089875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8099875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8109875cf80SDavid Howells unlikely(managed != 0)) { 811cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 812cc53ce53SDavid Howells * being held. */ 813cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 814cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 815cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8161aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 817cc53ce53SDavid Howells if (ret < 0) 8188aef1884SAl Viro break; 819cc53ce53SDavid Howells } 820cc53ce53SDavid Howells 8219875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8229875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8239875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8249875cf80SDavid Howells if (mounted) { 8259875cf80SDavid Howells dput(path->dentry); 8269875cf80SDavid Howells if (need_mntput) 827463ffb2eSAl Viro mntput(path->mnt); 828463ffb2eSAl Viro path->mnt = mounted; 829463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8309875cf80SDavid Howells need_mntput = true; 8319875cf80SDavid Howells continue; 832463ffb2eSAl Viro } 833463ffb2eSAl Viro 8349875cf80SDavid Howells /* Something is mounted on this dentry in another 8359875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8369875cf80SDavid Howells * namespace got unmounted before we managed to get the 8379875cf80SDavid Howells * vfsmount_lock */ 8381da177e4SLinus Torvalds } 8399875cf80SDavid Howells 8409875cf80SDavid Howells /* Handle an automount point */ 8419875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8429875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8439875cf80SDavid Howells if (ret < 0) 8448aef1884SAl Viro break; 8459875cf80SDavid Howells continue; 8469875cf80SDavid Howells } 8479875cf80SDavid Howells 8489875cf80SDavid Howells /* We didn't change the current path point */ 8499875cf80SDavid Howells break; 8509875cf80SDavid Howells } 8518aef1884SAl Viro 8528aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8538aef1884SAl Viro mntput(path->mnt); 8548aef1884SAl Viro if (ret == -EISDIR) 8558aef1884SAl Viro ret = 0; 856a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 8571da177e4SLinus Torvalds } 8581da177e4SLinus Torvalds 859cc53ce53SDavid Howells int follow_down_one(struct path *path) 8601da177e4SLinus Torvalds { 8611da177e4SLinus Torvalds struct vfsmount *mounted; 8621da177e4SLinus Torvalds 8631c755af4SAl Viro mounted = lookup_mnt(path); 8641da177e4SLinus Torvalds if (mounted) { 8659393bd07SAl Viro dput(path->dentry); 8669393bd07SAl Viro mntput(path->mnt); 8679393bd07SAl Viro path->mnt = mounted; 8689393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8691da177e4SLinus Torvalds return 1; 8701da177e4SLinus Torvalds } 8711da177e4SLinus Torvalds return 0; 8721da177e4SLinus Torvalds } 8731da177e4SLinus Torvalds 87462a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 87562a7375eSIan Kent { 87662a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 87762a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 87862a7375eSIan Kent } 87962a7375eSIan Kent 8809875cf80SDavid Howells /* 881287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 882287548e4SAl Viro * we meet a managed dentry that would need blocking. 8839875cf80SDavid Howells */ 8849875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 885287548e4SAl Viro struct inode **inode) 8869875cf80SDavid Howells { 88762a7375eSIan Kent for (;;) { 888c7105365SAl Viro struct mount *mounted; 88962a7375eSIan Kent /* 89062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 89162a7375eSIan Kent * that wants to block transit. 89262a7375eSIan Kent */ 893287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 894ab90911fSDavid Howells return false; 89562a7375eSIan Kent 89662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 89762a7375eSIan Kent break; 89862a7375eSIan Kent 8999875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9009875cf80SDavid Howells if (!mounted) 9019875cf80SDavid Howells break; 902c7105365SAl Viro path->mnt = &mounted->mnt; 903c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 904a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 9059875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 90659430262SLinus Torvalds /* 90759430262SLinus Torvalds * Update the inode too. We don't need to re-check the 90859430262SLinus Torvalds * dentry sequence number here after this d_inode read, 90959430262SLinus Torvalds * because a mount-point is always pinned. 91059430262SLinus Torvalds */ 91159430262SLinus Torvalds *inode = path->dentry->d_inode; 9129875cf80SDavid Howells } 9139875cf80SDavid Howells return true; 9149875cf80SDavid Howells } 9159875cf80SDavid Howells 916dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 917287548e4SAl Viro { 918dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 919c7105365SAl Viro struct mount *mounted; 920dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 921287548e4SAl Viro if (!mounted) 922287548e4SAl Viro break; 923c7105365SAl Viro nd->path.mnt = &mounted->mnt; 924c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 925dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 926287548e4SAl Viro } 927287548e4SAl Viro } 928287548e4SAl Viro 92931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 93031e6b01fSNick Piggin { 93131e6b01fSNick Piggin set_root_rcu(nd); 93231e6b01fSNick Piggin 93331e6b01fSNick Piggin while (1) { 93431e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 93531e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 93631e6b01fSNick Piggin break; 93731e6b01fSNick Piggin } 93831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 93931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 94031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 94131e6b01fSNick Piggin unsigned seq; 94231e6b01fSNick Piggin 94331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 94431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 945ef7562d5SAl Viro goto failed; 94631e6b01fSNick Piggin nd->path.dentry = parent; 94731e6b01fSNick Piggin nd->seq = seq; 94831e6b01fSNick Piggin break; 94931e6b01fSNick Piggin } 95031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 95131e6b01fSNick Piggin break; 95231e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 95331e6b01fSNick Piggin } 954dea39376SAl Viro follow_mount_rcu(nd); 955dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 95631e6b01fSNick Piggin return 0; 957ef7562d5SAl Viro 958ef7562d5SAl Viro failed: 959ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9605b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 961ef7562d5SAl Viro nd->root.mnt = NULL; 962ef7562d5SAl Viro rcu_read_unlock(); 963ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 964ef7562d5SAl Viro return -ECHILD; 96531e6b01fSNick Piggin } 96631e6b01fSNick Piggin 9679875cf80SDavid Howells /* 968cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 969cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 970cc53ce53SDavid Howells * caller is permitted to proceed or not. 971cc53ce53SDavid Howells */ 9727cc90cc3SAl Viro int follow_down(struct path *path) 973cc53ce53SDavid Howells { 974cc53ce53SDavid Howells unsigned managed; 975cc53ce53SDavid Howells int ret; 976cc53ce53SDavid Howells 977cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 978cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 979cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 980cc53ce53SDavid Howells * being held. 981cc53ce53SDavid Howells * 982cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 983cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 984cc53ce53SDavid Howells * other than its daemon the right to mount on its 985cc53ce53SDavid Howells * superstructure. 986cc53ce53SDavid Howells * 987cc53ce53SDavid Howells * The filesystem may sleep at this point. 988cc53ce53SDavid Howells */ 989cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 990cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 991cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 992ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 9931aed3e42SAl Viro path->dentry, false); 994cc53ce53SDavid Howells if (ret < 0) 995cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 996cc53ce53SDavid Howells } 997cc53ce53SDavid Howells 998cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 999cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1000cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1001cc53ce53SDavid Howells if (!mounted) 1002cc53ce53SDavid Howells break; 1003cc53ce53SDavid Howells dput(path->dentry); 1004cc53ce53SDavid Howells mntput(path->mnt); 1005cc53ce53SDavid Howells path->mnt = mounted; 1006cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1007cc53ce53SDavid Howells continue; 1008cc53ce53SDavid Howells } 1009cc53ce53SDavid Howells 1010cc53ce53SDavid Howells /* Don't handle automount points here */ 1011cc53ce53SDavid Howells break; 1012cc53ce53SDavid Howells } 1013cc53ce53SDavid Howells return 0; 1014cc53ce53SDavid Howells } 1015cc53ce53SDavid Howells 1016cc53ce53SDavid Howells /* 10179875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10189875cf80SDavid Howells */ 10199875cf80SDavid Howells static void follow_mount(struct path *path) 10209875cf80SDavid Howells { 10219875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10229875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10239875cf80SDavid Howells if (!mounted) 10249875cf80SDavid Howells break; 10259875cf80SDavid Howells dput(path->dentry); 10269875cf80SDavid Howells mntput(path->mnt); 10279875cf80SDavid Howells path->mnt = mounted; 10289875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10299875cf80SDavid Howells } 10309875cf80SDavid Howells } 10319875cf80SDavid Howells 103231e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10331da177e4SLinus Torvalds { 10342a737871SAl Viro set_root(nd); 1035e518ddb7SAndreas Mohr 10361da177e4SLinus Torvalds while(1) { 10374ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10381da177e4SLinus Torvalds 10392a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10402a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10411da177e4SLinus Torvalds break; 10421da177e4SLinus Torvalds } 10434ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10443088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10453088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10461da177e4SLinus Torvalds dput(old); 10471da177e4SLinus Torvalds break; 10481da177e4SLinus Torvalds } 10493088dd70SAl Viro if (!follow_up(&nd->path)) 10501da177e4SLinus Torvalds break; 10511da177e4SLinus Torvalds } 105279ed0226SAl Viro follow_mount(&nd->path); 105331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10541da177e4SLinus Torvalds } 10551da177e4SLinus Torvalds 10561da177e4SLinus Torvalds /* 1057baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1058baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1059baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1060baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1061baa03890SNick Piggin */ 1062baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1063baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1064baa03890SNick Piggin { 1065baa03890SNick Piggin struct inode *inode = parent->d_inode; 1066baa03890SNick Piggin struct dentry *dentry; 1067baa03890SNick Piggin struct dentry *old; 1068baa03890SNick Piggin 1069baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1070baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1071baa03890SNick Piggin return ERR_PTR(-ENOENT); 1072baa03890SNick Piggin 1073baa03890SNick Piggin dentry = d_alloc(parent, name); 1074baa03890SNick Piggin if (unlikely(!dentry)) 1075baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1076baa03890SNick Piggin 1077baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1078baa03890SNick Piggin if (unlikely(old)) { 1079baa03890SNick Piggin dput(dentry); 1080baa03890SNick Piggin dentry = old; 1081baa03890SNick Piggin } 1082baa03890SNick Piggin return dentry; 1083baa03890SNick Piggin } 1084baa03890SNick Piggin 1085baa03890SNick Piggin /* 108644396f4bSJosef Bacik * We already have a dentry, but require a lookup to be performed on the parent 108744396f4bSJosef Bacik * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. 108844396f4bSJosef Bacik * parent->d_inode->i_mutex must be held. d_lookup must have verified that no 108944396f4bSJosef Bacik * child exists while under i_mutex. 109044396f4bSJosef Bacik */ 109144396f4bSJosef Bacik static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, 109244396f4bSJosef Bacik struct nameidata *nd) 109344396f4bSJosef Bacik { 109444396f4bSJosef Bacik struct inode *inode = parent->d_inode; 109544396f4bSJosef Bacik struct dentry *old; 109644396f4bSJosef Bacik 109744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 109844396f4bSJosef Bacik if (unlikely(IS_DEADDIR(inode))) 109944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 110044396f4bSJosef Bacik 110144396f4bSJosef Bacik old = inode->i_op->lookup(inode, dentry, nd); 110244396f4bSJosef Bacik if (unlikely(old)) { 110344396f4bSJosef Bacik dput(dentry); 110444396f4bSJosef Bacik dentry = old; 110544396f4bSJosef Bacik } 110644396f4bSJosef Bacik return dentry; 110744396f4bSJosef Bacik } 110844396f4bSJosef Bacik 110944396f4bSJosef Bacik /* 11101da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11111da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11121da177e4SLinus Torvalds * It _is_ time-critical. 11131da177e4SLinus Torvalds */ 11141da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 111531e6b01fSNick Piggin struct path *path, struct inode **inode) 11161da177e4SLinus Torvalds { 11174ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 111831e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11195a18fff2SAl Viro int need_reval = 1; 11205a18fff2SAl Viro int status = 1; 11219875cf80SDavid Howells int err; 11229875cf80SDavid Howells 11233cac260aSAl Viro /* 1124b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1125b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1126b04f784eSNick Piggin * do the non-racy lookup, below. 1127b04f784eSNick Piggin */ 112831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 112931e6b01fSNick Piggin unsigned seq; 113031e6b01fSNick Piggin *inode = nd->inode; 113131e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11325a18fff2SAl Viro if (!dentry) 11335a18fff2SAl Viro goto unlazy; 11345a18fff2SAl Viro 113531e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 113631e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 113731e6b01fSNick Piggin return -ECHILD; 113831e6b01fSNick Piggin nd->seq = seq; 11395a18fff2SAl Viro 114024643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11415a18fff2SAl Viro status = d_revalidate(dentry, nd); 11425a18fff2SAl Viro if (unlikely(status <= 0)) { 11435a18fff2SAl Viro if (status != -ECHILD) 11445a18fff2SAl Viro need_reval = 0; 11455a18fff2SAl Viro goto unlazy; 11465a18fff2SAl Viro } 114724643087SAl Viro } 114844396f4bSJosef Bacik if (unlikely(d_need_lookup(dentry))) 114944396f4bSJosef Bacik goto unlazy; 115031e6b01fSNick Piggin path->mnt = mnt; 115131e6b01fSNick Piggin path->dentry = dentry; 1152d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1153d6e9bd25SAl Viro goto unlazy; 1154d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1155d6e9bd25SAl Viro goto unlazy; 11569875cf80SDavid Howells return 0; 11575a18fff2SAl Viro unlazy: 115819660af7SAl Viro if (unlazy_walk(nd, dentry)) 11595a18fff2SAl Viro return -ECHILD; 11605a18fff2SAl Viro } else { 116131e6b01fSNick Piggin dentry = __d_lookup(parent, name); 116224643087SAl Viro } 11635a18fff2SAl Viro 116444396f4bSJosef Bacik if (dentry && unlikely(d_need_lookup(dentry))) { 116544396f4bSJosef Bacik dput(dentry); 116644396f4bSJosef Bacik dentry = NULL; 116744396f4bSJosef Bacik } 11685a18fff2SAl Viro retry: 11695a18fff2SAl Viro if (unlikely(!dentry)) { 11705a18fff2SAl Viro struct inode *dir = parent->d_inode; 11715a18fff2SAl Viro BUG_ON(nd->inode != dir); 11725a18fff2SAl Viro 11735a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11745a18fff2SAl Viro dentry = d_lookup(parent, name); 11755a18fff2SAl Viro if (likely(!dentry)) { 11765a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 11775a18fff2SAl Viro if (IS_ERR(dentry)) { 11785a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11795a18fff2SAl Viro return PTR_ERR(dentry); 11805a18fff2SAl Viro } 11815a18fff2SAl Viro /* known good */ 11825a18fff2SAl Viro need_reval = 0; 11835a18fff2SAl Viro status = 1; 118444396f4bSJosef Bacik } else if (unlikely(d_need_lookup(dentry))) { 118544396f4bSJosef Bacik dentry = d_inode_lookup(parent, dentry, nd); 118644396f4bSJosef Bacik if (IS_ERR(dentry)) { 118744396f4bSJosef Bacik mutex_unlock(&dir->i_mutex); 118844396f4bSJosef Bacik return PTR_ERR(dentry); 118944396f4bSJosef Bacik } 119044396f4bSJosef Bacik /* known good */ 119144396f4bSJosef Bacik need_reval = 0; 119244396f4bSJosef Bacik status = 1; 11935a18fff2SAl Viro } 11945a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11955a18fff2SAl Viro } 11965a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 11975a18fff2SAl Viro status = d_revalidate(dentry, nd); 11985a18fff2SAl Viro if (unlikely(status <= 0)) { 11995a18fff2SAl Viro if (status < 0) { 12005a18fff2SAl Viro dput(dentry); 12015a18fff2SAl Viro return status; 12025a18fff2SAl Viro } 12035a18fff2SAl Viro if (!d_invalidate(dentry)) { 12045a18fff2SAl Viro dput(dentry); 12055a18fff2SAl Viro dentry = NULL; 12065a18fff2SAl Viro need_reval = 1; 12075a18fff2SAl Viro goto retry; 12085a18fff2SAl Viro } 12095a18fff2SAl Viro } 12105a18fff2SAl Viro 12111da177e4SLinus Torvalds path->mnt = mnt; 12121da177e4SLinus Torvalds path->dentry = dentry; 12139875cf80SDavid Howells err = follow_managed(path, nd->flags); 121489312214SIan Kent if (unlikely(err < 0)) { 121589312214SIan Kent path_put_conditional(path, nd); 12169875cf80SDavid Howells return err; 121789312214SIan Kent } 1218a3fbbde7SAl Viro if (err) 1219a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 122031e6b01fSNick Piggin *inode = path->dentry->d_inode; 12211da177e4SLinus Torvalds return 0; 12221da177e4SLinus Torvalds } 12231da177e4SLinus Torvalds 122452094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 122552094c8aSAl Viro { 122652094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 12274ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 122852094c8aSAl Viro if (err != -ECHILD) 122952094c8aSAl Viro return err; 123019660af7SAl Viro if (unlazy_walk(nd, NULL)) 123152094c8aSAl Viro return -ECHILD; 123252094c8aSAl Viro } 12334ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 123452094c8aSAl Viro } 123552094c8aSAl Viro 12369856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12379856fa1bSAl Viro { 12389856fa1bSAl Viro if (type == LAST_DOTDOT) { 12399856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12409856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12419856fa1bSAl Viro return -ECHILD; 12429856fa1bSAl Viro } else 12439856fa1bSAl Viro follow_dotdot(nd); 12449856fa1bSAl Viro } 12459856fa1bSAl Viro return 0; 12469856fa1bSAl Viro } 12479856fa1bSAl Viro 1248951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1249951361f9SAl Viro { 1250951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1251951361f9SAl Viro path_put(&nd->path); 1252951361f9SAl Viro } else { 1253951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12545b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1255951361f9SAl Viro nd->root.mnt = NULL; 1256951361f9SAl Viro rcu_read_unlock(); 1257951361f9SAl Viro br_read_unlock(vfsmount_lock); 1258951361f9SAl Viro } 1259951361f9SAl Viro } 1260951361f9SAl Viro 12613ddcd056SLinus Torvalds /* 12623ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 12633ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 12643ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 12653ddcd056SLinus Torvalds * for the common case. 12663ddcd056SLinus Torvalds */ 12677813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 12683ddcd056SLinus Torvalds { 12693ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 12703ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 12713ddcd056SLinus Torvalds return follow; 12723ddcd056SLinus Torvalds 12733ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 12743ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 12753ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 12763ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 12773ddcd056SLinus Torvalds } 12783ddcd056SLinus Torvalds return 0; 12793ddcd056SLinus Torvalds } 12803ddcd056SLinus Torvalds 1281ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1282ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1283ce57dfc1SAl Viro { 1284ce57dfc1SAl Viro struct inode *inode; 1285ce57dfc1SAl Viro int err; 1286ce57dfc1SAl Viro /* 1287ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1288ce57dfc1SAl Viro * to be able to know about the current root directory and 1289ce57dfc1SAl Viro * parent relationships. 1290ce57dfc1SAl Viro */ 1291ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1292ce57dfc1SAl Viro return handle_dots(nd, type); 1293ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1294ce57dfc1SAl Viro if (unlikely(err)) { 1295ce57dfc1SAl Viro terminate_walk(nd); 1296ce57dfc1SAl Viro return err; 1297ce57dfc1SAl Viro } 1298ce57dfc1SAl Viro if (!inode) { 1299ce57dfc1SAl Viro path_to_nameidata(path, nd); 1300ce57dfc1SAl Viro terminate_walk(nd); 1301ce57dfc1SAl Viro return -ENOENT; 1302ce57dfc1SAl Viro } 13037813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 130419660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 130519660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 130619660af7SAl Viro terminate_walk(nd); 1307ce57dfc1SAl Viro return -ECHILD; 130819660af7SAl Viro } 130919660af7SAl Viro } 1310ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1311ce57dfc1SAl Viro return 1; 1312ce57dfc1SAl Viro } 1313ce57dfc1SAl Viro path_to_nameidata(path, nd); 1314ce57dfc1SAl Viro nd->inode = inode; 1315ce57dfc1SAl Viro return 0; 1316ce57dfc1SAl Viro } 1317ce57dfc1SAl Viro 13181da177e4SLinus Torvalds /* 1319b356379aSAl Viro * This limits recursive symlink follows to 8, while 1320b356379aSAl Viro * limiting consecutive symlinks to 40. 1321b356379aSAl Viro * 1322b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1323b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1324b356379aSAl Viro */ 1325b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1326b356379aSAl Viro { 1327b356379aSAl Viro int res; 1328b356379aSAl Viro 1329b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1330b356379aSAl Viro path_put_conditional(path, nd); 1331b356379aSAl Viro path_put(&nd->path); 1332b356379aSAl Viro return -ELOOP; 1333b356379aSAl Viro } 13341a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1335b356379aSAl Viro 1336b356379aSAl Viro nd->depth++; 1337b356379aSAl Viro current->link_count++; 1338b356379aSAl Viro 1339b356379aSAl Viro do { 1340b356379aSAl Viro struct path link = *path; 1341b356379aSAl Viro void *cookie; 1342574197e0SAl Viro 1343574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1344b356379aSAl Viro if (!res) 1345b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1346b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1347574197e0SAl Viro put_link(nd, &link, cookie); 1348b356379aSAl Viro } while (res > 0); 1349b356379aSAl Viro 1350b356379aSAl Viro current->link_count--; 1351b356379aSAl Viro nd->depth--; 1352b356379aSAl Viro return res; 1353b356379aSAl Viro } 1354b356379aSAl Viro 1355b356379aSAl Viro /* 13563ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 13573ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 13583ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 13593ddcd056SLinus Torvalds * do lookup on this inode". 13603ddcd056SLinus Torvalds */ 13613ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 13623ddcd056SLinus Torvalds { 13633ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 13643ddcd056SLinus Torvalds return 1; 13653ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 13663ddcd056SLinus Torvalds return 0; 13673ddcd056SLinus Torvalds 13683ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 13693ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13703ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 13713ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13723ddcd056SLinus Torvalds return 1; 13733ddcd056SLinus Torvalds } 13743ddcd056SLinus Torvalds 13753ddcd056SLinus Torvalds /* 13761da177e4SLinus Torvalds * Name resolution. 1377ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1378ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13791da177e4SLinus Torvalds * 1380ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1381ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13821da177e4SLinus Torvalds */ 13836de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13841da177e4SLinus Torvalds { 13851da177e4SLinus Torvalds struct path next; 13861da177e4SLinus Torvalds int err; 13871da177e4SLinus Torvalds 13881da177e4SLinus Torvalds while (*name=='/') 13891da177e4SLinus Torvalds name++; 13901da177e4SLinus Torvalds if (!*name) 1391086e183aSAl Viro return 0; 13921da177e4SLinus Torvalds 13931da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13941da177e4SLinus Torvalds for(;;) { 13951da177e4SLinus Torvalds unsigned long hash; 13961da177e4SLinus Torvalds struct qstr this; 13971da177e4SLinus Torvalds unsigned int c; 1398fe479a58SAl Viro int type; 13991da177e4SLinus Torvalds 140052094c8aSAl Viro err = may_lookup(nd); 14011da177e4SLinus Torvalds if (err) 14021da177e4SLinus Torvalds break; 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds this.name = name; 14051da177e4SLinus Torvalds c = *(const unsigned char *)name; 14061da177e4SLinus Torvalds 14071da177e4SLinus Torvalds hash = init_name_hash(); 14081da177e4SLinus Torvalds do { 14091da177e4SLinus Torvalds name++; 14101da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 14111da177e4SLinus Torvalds c = *(const unsigned char *)name; 14121da177e4SLinus Torvalds } while (c && (c != '/')); 14131da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14141da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14151da177e4SLinus Torvalds 1416fe479a58SAl Viro type = LAST_NORM; 1417fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1418fe479a58SAl Viro case 2: 141916c2cd71SAl Viro if (this.name[1] == '.') { 1420fe479a58SAl Viro type = LAST_DOTDOT; 142116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 142216c2cd71SAl Viro } 1423fe479a58SAl Viro break; 1424fe479a58SAl Viro case 1: 1425fe479a58SAl Viro type = LAST_DOT; 1426fe479a58SAl Viro } 14275a202bcdSAl Viro if (likely(type == LAST_NORM)) { 14285a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 142916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14305a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14315a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14325a202bcdSAl Viro &this); 14335a202bcdSAl Viro if (err < 0) 14345a202bcdSAl Viro break; 14355a202bcdSAl Viro } 14365a202bcdSAl Viro } 1437fe479a58SAl Viro 14381da177e4SLinus Torvalds /* remove trailing slashes? */ 14391da177e4SLinus Torvalds if (!c) 14401da177e4SLinus Torvalds goto last_component; 14411da177e4SLinus Torvalds while (*++name == '/'); 14421da177e4SLinus Torvalds if (!*name) 1443b356379aSAl Viro goto last_component; 14441da177e4SLinus Torvalds 1445ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1446ce57dfc1SAl Viro if (err < 0) 1447ce57dfc1SAl Viro return err; 1448fe479a58SAl Viro 1449ce57dfc1SAl Viro if (err) { 1450b356379aSAl Viro err = nested_symlink(&next, nd); 14511da177e4SLinus Torvalds if (err) 1452a7472babSAl Viro return err; 145331e6b01fSNick Piggin } 14543ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 14551da177e4SLinus Torvalds continue; 14563ddcd056SLinus Torvalds err = -ENOTDIR; 14573ddcd056SLinus Torvalds break; 14581da177e4SLinus Torvalds /* here ends the main loop */ 14591da177e4SLinus Torvalds 14601da177e4SLinus Torvalds last_component: 1461ce57dfc1SAl Viro nd->last = this; 1462ce57dfc1SAl Viro nd->last_type = type; 1463ce57dfc1SAl Viro return 0; 1464ce57dfc1SAl Viro } 1465951361f9SAl Viro terminate_walk(nd); 14661da177e4SLinus Torvalds return err; 14671da177e4SLinus Torvalds } 14681da177e4SLinus Torvalds 146970e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 147070e9b357SAl Viro struct nameidata *nd, struct file **fp) 147131e6b01fSNick Piggin { 147231e6b01fSNick Piggin int retval = 0; 147331e6b01fSNick Piggin int fput_needed; 147431e6b01fSNick Piggin struct file *file; 147531e6b01fSNick Piggin 147631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 147716c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 147831e6b01fSNick Piggin nd->depth = 0; 14795b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14805b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 148173d049a4SAl Viro if (*name) { 14825b6ca027SAl Viro if (!inode->i_op->lookup) 14835b6ca027SAl Viro return -ENOTDIR; 14845b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14855b6ca027SAl Viro if (retval) 14865b6ca027SAl Viro return retval; 148773d049a4SAl Viro } 14885b6ca027SAl Viro nd->path = nd->root; 14895b6ca027SAl Viro nd->inode = inode; 14905b6ca027SAl Viro if (flags & LOOKUP_RCU) { 14915b6ca027SAl Viro br_read_lock(vfsmount_lock); 14925b6ca027SAl Viro rcu_read_lock(); 14935b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 14945b6ca027SAl Viro } else { 14955b6ca027SAl Viro path_get(&nd->path); 14965b6ca027SAl Viro } 14975b6ca027SAl Viro return 0; 14985b6ca027SAl Viro } 14995b6ca027SAl Viro 150031e6b01fSNick Piggin nd->root.mnt = NULL; 150131e6b01fSNick Piggin 150231e6b01fSNick Piggin if (*name=='/') { 1503e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 150431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 150531e6b01fSNick Piggin rcu_read_lock(); 1506e41f7d4eSAl Viro set_root_rcu(nd); 1507e41f7d4eSAl Viro } else { 1508e41f7d4eSAl Viro set_root(nd); 1509e41f7d4eSAl Viro path_get(&nd->root); 1510e41f7d4eSAl Viro } 151131e6b01fSNick Piggin nd->path = nd->root; 151231e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1513e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 151431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1515c28cc364SNick Piggin unsigned seq; 151631e6b01fSNick Piggin 151731e6b01fSNick Piggin br_read_lock(vfsmount_lock); 151831e6b01fSNick Piggin rcu_read_lock(); 151931e6b01fSNick Piggin 1520c28cc364SNick Piggin do { 1521c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 152231e6b01fSNick Piggin nd->path = fs->pwd; 1523c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1524c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1525e41f7d4eSAl Viro } else { 1526e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1527e41f7d4eSAl Viro } 152831e6b01fSNick Piggin } else { 152931e6b01fSNick Piggin struct dentry *dentry; 153031e6b01fSNick Piggin 15311abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 153231e6b01fSNick Piggin retval = -EBADF; 153331e6b01fSNick Piggin if (!file) 153431e6b01fSNick Piggin goto out_fail; 153531e6b01fSNick Piggin 153631e6b01fSNick Piggin dentry = file->f_path.dentry; 153731e6b01fSNick Piggin 1538f52e0c11SAl Viro if (*name) { 153931e6b01fSNick Piggin retval = -ENOTDIR; 154031e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 154131e6b01fSNick Piggin goto fput_fail; 154231e6b01fSNick Piggin 15434ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 154431e6b01fSNick Piggin if (retval) 154531e6b01fSNick Piggin goto fput_fail; 1546f52e0c11SAl Viro } 154731e6b01fSNick Piggin 154831e6b01fSNick Piggin nd->path = file->f_path; 1549e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 155031e6b01fSNick Piggin if (fput_needed) 155170e9b357SAl Viro *fp = file; 1552c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 155331e6b01fSNick Piggin br_read_lock(vfsmount_lock); 155431e6b01fSNick Piggin rcu_read_lock(); 15555590ff0dSUlrich Drepper } else { 15565dd784d0SJan Blunck path_get(&file->f_path); 15575590ff0dSUlrich Drepper fput_light(file, fput_needed); 15581da177e4SLinus Torvalds } 1559e41f7d4eSAl Viro } 1560e41f7d4eSAl Viro 156131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15629b4a9b14SAl Viro return 0; 15632dfdd266SJosef 'Jeff' Sipek 15649b4a9b14SAl Viro fput_fail: 15659b4a9b14SAl Viro fput_light(file, fput_needed); 15669b4a9b14SAl Viro out_fail: 15679b4a9b14SAl Viro return retval; 15689b4a9b14SAl Viro } 15699b4a9b14SAl Viro 1570bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1571bd92d7feSAl Viro { 1572bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1573bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1574bd92d7feSAl Viro 1575bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1576bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1577bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1578bd92d7feSAl Viro } 1579bd92d7feSAl Viro 15809b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1581ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15829b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15839b4a9b14SAl Viro { 158470e9b357SAl Viro struct file *base = NULL; 1585bd92d7feSAl Viro struct path path; 1586bd92d7feSAl Viro int err; 158731e6b01fSNick Piggin 158831e6b01fSNick Piggin /* 158931e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 159031e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 159131e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 159231e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 159331e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 159431e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 159531e6b01fSNick Piggin * analogue, foo_rcu(). 159631e6b01fSNick Piggin * 159731e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 159831e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 159931e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 160031e6b01fSNick Piggin * be able to complete). 160131e6b01fSNick Piggin */ 1602bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1603ee0827cdSAl Viro 1604bd92d7feSAl Viro if (unlikely(err)) 1605bd92d7feSAl Viro return err; 1606ee0827cdSAl Viro 1607ee0827cdSAl Viro current->total_link_count = 0; 1608bd92d7feSAl Viro err = link_path_walk(name, nd); 1609bd92d7feSAl Viro 1610bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1611bd92d7feSAl Viro err = lookup_last(nd, &path); 1612bd92d7feSAl Viro while (err > 0) { 1613bd92d7feSAl Viro void *cookie; 1614bd92d7feSAl Viro struct path link = path; 1615bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1616574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1617bd92d7feSAl Viro if (!err) 1618bd92d7feSAl Viro err = lookup_last(nd, &path); 1619574197e0SAl Viro put_link(nd, &link, cookie); 1620bd92d7feSAl Viro } 1621bd92d7feSAl Viro } 1622ee0827cdSAl Viro 16239f1fafeeSAl Viro if (!err) 16249f1fafeeSAl Viro err = complete_walk(nd); 1625bd92d7feSAl Viro 1626bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1627bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1628bd92d7feSAl Viro path_put(&nd->path); 1629bd23a539SAl Viro err = -ENOTDIR; 1630bd92d7feSAl Viro } 1631bd92d7feSAl Viro } 163216c2cd71SAl Viro 163370e9b357SAl Viro if (base) 163470e9b357SAl Viro fput(base); 1635ee0827cdSAl Viro 16365b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 163731e6b01fSNick Piggin path_put(&nd->root); 163831e6b01fSNick Piggin nd->root.mnt = NULL; 163931e6b01fSNick Piggin } 1640bd92d7feSAl Viro return err; 164131e6b01fSNick Piggin } 164231e6b01fSNick Piggin 1643ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1644ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1645ee0827cdSAl Viro { 1646ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1647ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1648ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1649ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1650ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1651ee0827cdSAl Viro 165231e6b01fSNick Piggin if (likely(!retval)) { 165331e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 165431e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 165531e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 165631e6b01fSNick Piggin } 165731e6b01fSNick Piggin } 1658170aa3d0SUlrich Drepper return retval; 16591da177e4SLinus Torvalds } 16601da177e4SLinus Torvalds 1661c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16625590ff0dSUlrich Drepper { 1663c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16645590ff0dSUlrich Drepper } 16655590ff0dSUlrich Drepper 1666d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1667d1811465SAl Viro { 1668d1811465SAl Viro struct nameidata nd; 1669d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1670d1811465SAl Viro if (!res) 1671d1811465SAl Viro *path = nd.path; 1672d1811465SAl Viro return res; 1673d1811465SAl Viro } 1674d1811465SAl Viro 167516f18200SJosef 'Jeff' Sipek /** 167616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 167716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 167816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 167916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 168016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1681e0a01249SAl Viro * @path: pointer to struct path to fill 168216f18200SJosef 'Jeff' Sipek */ 168316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 168416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1685e0a01249SAl Viro struct path *path) 168616f18200SJosef 'Jeff' Sipek { 1687e0a01249SAl Viro struct nameidata nd; 1688e0a01249SAl Viro int err; 1689e0a01249SAl Viro nd.root.dentry = dentry; 1690e0a01249SAl Viro nd.root.mnt = mnt; 1691e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 16925b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1693e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1694e0a01249SAl Viro if (!err) 1695e0a01249SAl Viro *path = nd.path; 1696e0a01249SAl Viro return err; 169716f18200SJosef 'Jeff' Sipek } 169816f18200SJosef 'Jeff' Sipek 1699eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1700eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 17011da177e4SLinus Torvalds { 170281fca444SChristoph Hellwig struct inode *inode = base->d_inode; 17031da177e4SLinus Torvalds struct dentry *dentry; 17041da177e4SLinus Torvalds int err; 17051da177e4SLinus Torvalds 17064ad5abb3SAl Viro err = inode_permission(inode, MAY_EXEC); 170781fca444SChristoph Hellwig if (err) 170881fca444SChristoph Hellwig return ERR_PTR(err); 17091da177e4SLinus Torvalds 17101da177e4SLinus Torvalds /* 1711b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1712b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1713b04f784eSNick Piggin * a double lookup. 17146e6b1bd1SAl Viro */ 17156e6b1bd1SAl Viro dentry = d_lookup(base, name); 17166e6b1bd1SAl Viro 171744396f4bSJosef Bacik if (dentry && d_need_lookup(dentry)) { 171844396f4bSJosef Bacik /* 171944396f4bSJosef Bacik * __lookup_hash is called with the parent dir's i_mutex already 172044396f4bSJosef Bacik * held, so we are good to go here. 172144396f4bSJosef Bacik */ 172244396f4bSJosef Bacik dentry = d_inode_lookup(base, dentry, nd); 172344396f4bSJosef Bacik if (IS_ERR(dentry)) 172444396f4bSJosef Bacik return dentry; 172544396f4bSJosef Bacik } 172644396f4bSJosef Bacik 1727d2d9e9fbSAl Viro if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { 1728d2d9e9fbSAl Viro int status = d_revalidate(dentry, nd); 1729d2d9e9fbSAl Viro if (unlikely(status <= 0)) { 1730d2d9e9fbSAl Viro /* 1731d2d9e9fbSAl Viro * The dentry failed validation. 1732d2d9e9fbSAl Viro * If d_revalidate returned 0 attempt to invalidate 1733d2d9e9fbSAl Viro * the dentry otherwise d_revalidate is asking us 1734d2d9e9fbSAl Viro * to return a fail status. 1735d2d9e9fbSAl Viro */ 1736d2d9e9fbSAl Viro if (status < 0) { 1737d2d9e9fbSAl Viro dput(dentry); 1738d2d9e9fbSAl Viro return ERR_PTR(status); 1739d2d9e9fbSAl Viro } else if (!d_invalidate(dentry)) { 1740d2d9e9fbSAl Viro dput(dentry); 1741d2d9e9fbSAl Viro dentry = NULL; 1742d2d9e9fbSAl Viro } 1743d2d9e9fbSAl Viro } 1744d2d9e9fbSAl Viro } 17456e6b1bd1SAl Viro 17461da177e4SLinus Torvalds if (!dentry) 1747baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17485a202bcdSAl Viro 17491da177e4SLinus Torvalds return dentry; 17501da177e4SLinus Torvalds } 17511da177e4SLinus Torvalds 1752057f6c01SJames Morris /* 1753057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1754057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1755057f6c01SJames Morris * SMP-safe. 1756057f6c01SJames Morris */ 1757a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17581da177e4SLinus Torvalds { 17594ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17601da177e4SLinus Torvalds } 17611da177e4SLinus Torvalds 1762eead1911SChristoph Hellwig /** 1763a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1764eead1911SChristoph Hellwig * @name: pathname component to lookup 1765eead1911SChristoph Hellwig * @base: base directory to lookup from 1766eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1767eead1911SChristoph Hellwig * 1768a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1769a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1770eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1771eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1772eead1911SChristoph Hellwig */ 1773057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1774057f6c01SJames Morris { 1775057f6c01SJames Morris struct qstr this; 17766a96ba54SAl Viro unsigned long hash; 17776a96ba54SAl Viro unsigned int c; 1778057f6c01SJames Morris 17792f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17802f9092e1SDavid Woodhouse 17816a96ba54SAl Viro this.name = name; 17826a96ba54SAl Viro this.len = len; 17836a96ba54SAl Viro if (!len) 17846a96ba54SAl Viro return ERR_PTR(-EACCES); 17856a96ba54SAl Viro 17866a96ba54SAl Viro hash = init_name_hash(); 17876a96ba54SAl Viro while (len--) { 17886a96ba54SAl Viro c = *(const unsigned char *)name++; 17896a96ba54SAl Viro if (c == '/' || c == '\0') 17906a96ba54SAl Viro return ERR_PTR(-EACCES); 17916a96ba54SAl Viro hash = partial_name_hash(c, hash); 17926a96ba54SAl Viro } 17936a96ba54SAl Viro this.hash = end_name_hash(hash); 17945a202bcdSAl Viro /* 17955a202bcdSAl Viro * See if the low-level filesystem might want 17965a202bcdSAl Viro * to use its own hash.. 17975a202bcdSAl Viro */ 17985a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17995a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 18005a202bcdSAl Viro if (err < 0) 18015a202bcdSAl Viro return ERR_PTR(err); 18025a202bcdSAl Viro } 1803eead1911SChristoph Hellwig 180449705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1805057f6c01SJames Morris } 1806057f6c01SJames Morris 18071fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 18081fa1e7f6SAndy Whitcroft struct path *path, int *empty) 18091da177e4SLinus Torvalds { 18102d8f3038SAl Viro struct nameidata nd; 18111fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 18121da177e4SLinus Torvalds int err = PTR_ERR(tmp); 18131da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 18142d8f3038SAl Viro 18152d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18162d8f3038SAl Viro 18172d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 18181da177e4SLinus Torvalds putname(tmp); 18192d8f3038SAl Viro if (!err) 18202d8f3038SAl Viro *path = nd.path; 18211da177e4SLinus Torvalds } 18221da177e4SLinus Torvalds return err; 18231da177e4SLinus Torvalds } 18241da177e4SLinus Torvalds 18251fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 18261fa1e7f6SAndy Whitcroft struct path *path) 18271fa1e7f6SAndy Whitcroft { 18281fa1e7f6SAndy Whitcroft return user_path_at_empty(dfd, name, flags, path, 0); 18291fa1e7f6SAndy Whitcroft } 18301fa1e7f6SAndy Whitcroft 18312ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 18322ad94ae6SAl Viro struct nameidata *nd, char **name) 18332ad94ae6SAl Viro { 18342ad94ae6SAl Viro char *s = getname(path); 18352ad94ae6SAl Viro int error; 18362ad94ae6SAl Viro 18372ad94ae6SAl Viro if (IS_ERR(s)) 18382ad94ae6SAl Viro return PTR_ERR(s); 18392ad94ae6SAl Viro 18402ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 18412ad94ae6SAl Viro if (error) 18422ad94ae6SAl Viro putname(s); 18432ad94ae6SAl Viro else 18442ad94ae6SAl Viro *name = s; 18452ad94ae6SAl Viro 18462ad94ae6SAl Viro return error; 18472ad94ae6SAl Viro } 18482ad94ae6SAl Viro 18491da177e4SLinus Torvalds /* 18501da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18511da177e4SLinus Torvalds * minimal. 18521da177e4SLinus Torvalds */ 18531da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18541da177e4SLinus Torvalds { 1855da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1856da9592edSDavid Howells 18571da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18581da177e4SLinus Torvalds return 0; 1859e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1860e795b717SSerge E. Hallyn goto other_userns; 1861da9592edSDavid Howells if (inode->i_uid == fsuid) 18621da177e4SLinus Torvalds return 0; 1863da9592edSDavid Howells if (dir->i_uid == fsuid) 18641da177e4SLinus Torvalds return 0; 1865e795b717SSerge E. Hallyn 1866e795b717SSerge E. Hallyn other_userns: 1867e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 18681da177e4SLinus Torvalds } 18691da177e4SLinus Torvalds 18701da177e4SLinus Torvalds /* 18711da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18721da177e4SLinus Torvalds * whether the type of victim is right. 18731da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18741da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18751da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18761da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18771da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18781da177e4SLinus Torvalds * a. be owner of dir, or 18791da177e4SLinus Torvalds * b. be owner of victim, or 18801da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18811da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18821da177e4SLinus Torvalds * links pointing to it. 18831da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18841da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18851da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18861da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18871da177e4SLinus Torvalds * nfs_async_unlink(). 18881da177e4SLinus Torvalds */ 1889858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18901da177e4SLinus Torvalds { 18911da177e4SLinus Torvalds int error; 18921da177e4SLinus Torvalds 18931da177e4SLinus Torvalds if (!victim->d_inode) 18941da177e4SLinus Torvalds return -ENOENT; 18951da177e4SLinus Torvalds 18961da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1897cccc6bbaSAl Viro audit_inode_child(victim, dir); 18981da177e4SLinus Torvalds 1899f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 19001da177e4SLinus Torvalds if (error) 19011da177e4SLinus Torvalds return error; 19021da177e4SLinus Torvalds if (IS_APPEND(dir)) 19031da177e4SLinus Torvalds return -EPERM; 19041da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1905f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 19061da177e4SLinus Torvalds return -EPERM; 19071da177e4SLinus Torvalds if (isdir) { 19081da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 19091da177e4SLinus Torvalds return -ENOTDIR; 19101da177e4SLinus Torvalds if (IS_ROOT(victim)) 19111da177e4SLinus Torvalds return -EBUSY; 19121da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 19131da177e4SLinus Torvalds return -EISDIR; 19141da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19151da177e4SLinus Torvalds return -ENOENT; 19161da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 19171da177e4SLinus Torvalds return -EBUSY; 19181da177e4SLinus Torvalds return 0; 19191da177e4SLinus Torvalds } 19201da177e4SLinus Torvalds 19211da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 19221da177e4SLinus Torvalds * dir. 19231da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 19241da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 19251da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 19261da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 19271da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 19281da177e4SLinus Torvalds */ 1929a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 19301da177e4SLinus Torvalds { 19311da177e4SLinus Torvalds if (child->d_inode) 19321da177e4SLinus Torvalds return -EEXIST; 19331da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19341da177e4SLinus Torvalds return -ENOENT; 1935f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 19361da177e4SLinus Torvalds } 19371da177e4SLinus Torvalds 19381da177e4SLinus Torvalds /* 19391da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 19401da177e4SLinus Torvalds */ 19411da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 19421da177e4SLinus Torvalds { 19431da177e4SLinus Torvalds struct dentry *p; 19441da177e4SLinus Torvalds 19451da177e4SLinus Torvalds if (p1 == p2) { 1946f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 19471da177e4SLinus Torvalds return NULL; 19481da177e4SLinus Torvalds } 19491da177e4SLinus Torvalds 1950a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19511da177e4SLinus Torvalds 1952e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1953e2761a11SOGAWA Hirofumi if (p) { 1954f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1955f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19561da177e4SLinus Torvalds return p; 19571da177e4SLinus Torvalds } 19581da177e4SLinus Torvalds 1959e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1960e2761a11SOGAWA Hirofumi if (p) { 1961f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1962f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19631da177e4SLinus Torvalds return p; 19641da177e4SLinus Torvalds } 19651da177e4SLinus Torvalds 1966f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1967f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19681da177e4SLinus Torvalds return NULL; 19691da177e4SLinus Torvalds } 19701da177e4SLinus Torvalds 19711da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19721da177e4SLinus Torvalds { 19731b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19741da177e4SLinus Torvalds if (p1 != p2) { 19751b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1976a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19771da177e4SLinus Torvalds } 19781da177e4SLinus Torvalds } 19791da177e4SLinus Torvalds 19804acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 19811da177e4SLinus Torvalds struct nameidata *nd) 19821da177e4SLinus Torvalds { 1983a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19841da177e4SLinus Torvalds 19851da177e4SLinus Torvalds if (error) 19861da177e4SLinus Torvalds return error; 19871da177e4SLinus Torvalds 1988acfa4380SAl Viro if (!dir->i_op->create) 19891da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19901da177e4SLinus Torvalds mode &= S_IALLUGO; 19911da177e4SLinus Torvalds mode |= S_IFREG; 19921da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19931da177e4SLinus Torvalds if (error) 19941da177e4SLinus Torvalds return error; 19951da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1996a74574aaSStephen Smalley if (!error) 1997f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19981da177e4SLinus Torvalds return error; 19991da177e4SLinus Torvalds } 20001da177e4SLinus Torvalds 200173d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 20021da177e4SLinus Torvalds { 20033fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 20041da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 20051da177e4SLinus Torvalds int error; 20061da177e4SLinus Torvalds 2007bcda7652SAl Viro /* O_PATH? */ 2008bcda7652SAl Viro if (!acc_mode) 2009bcda7652SAl Viro return 0; 2010bcda7652SAl Viro 20111da177e4SLinus Torvalds if (!inode) 20121da177e4SLinus Torvalds return -ENOENT; 20131da177e4SLinus Torvalds 2014c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2015c8fe8f30SChristoph Hellwig case S_IFLNK: 20161da177e4SLinus Torvalds return -ELOOP; 2017c8fe8f30SChristoph Hellwig case S_IFDIR: 2018c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 20191da177e4SLinus Torvalds return -EISDIR; 2020c8fe8f30SChristoph Hellwig break; 2021c8fe8f30SChristoph Hellwig case S_IFBLK: 2022c8fe8f30SChristoph Hellwig case S_IFCHR: 20233fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 20241da177e4SLinus Torvalds return -EACCES; 2025c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2026c8fe8f30SChristoph Hellwig case S_IFIFO: 2027c8fe8f30SChristoph Hellwig case S_IFSOCK: 20281da177e4SLinus Torvalds flag &= ~O_TRUNC; 2029c8fe8f30SChristoph Hellwig break; 20304a3fd211SDave Hansen } 2031b41572e9SDave Hansen 20323fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2033b41572e9SDave Hansen if (error) 2034b41572e9SDave Hansen return error; 20356146f0d5SMimi Zohar 20361da177e4SLinus Torvalds /* 20371da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 20381da177e4SLinus Torvalds */ 20391da177e4SLinus Torvalds if (IS_APPEND(inode)) { 20408737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 20417715b521SAl Viro return -EPERM; 20421da177e4SLinus Torvalds if (flag & O_TRUNC) 20437715b521SAl Viro return -EPERM; 20441da177e4SLinus Torvalds } 20451da177e4SLinus Torvalds 20461da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 20472e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 20487715b521SAl Viro return -EPERM; 20491da177e4SLinus Torvalds 2050f3c7691eSJ. Bruce Fields return 0; 20517715b521SAl Viro } 20527715b521SAl Viro 2053e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20547715b521SAl Viro { 2055e1181ee6SJeff Layton struct path *path = &filp->f_path; 20567715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20577715b521SAl Viro int error = get_write_access(inode); 20581da177e4SLinus Torvalds if (error) 20597715b521SAl Viro return error; 20601da177e4SLinus Torvalds /* 20611da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20621da177e4SLinus Torvalds */ 20631da177e4SLinus Torvalds error = locks_verify_locked(inode); 2064be6d3e56SKentaro Takeda if (!error) 2065ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20661da177e4SLinus Torvalds if (!error) { 20677715b521SAl Viro error = do_truncate(path->dentry, 0, 2068d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2069e1181ee6SJeff Layton filp); 20701da177e4SLinus Torvalds } 20711da177e4SLinus Torvalds put_write_access(inode); 2072acd0c935SMimi Zohar return error; 20731da177e4SLinus Torvalds } 20741da177e4SLinus Torvalds 2075d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2076d57999e1SDave Hansen { 20778a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 20788a5e929dSAl Viro flag--; 2079d57999e1SDave Hansen return flag; 2080d57999e1SDave Hansen } 2081d57999e1SDave Hansen 208231e6b01fSNick Piggin /* 2083fe2d35ffSAl Viro * Handle the last step of open() 208431e6b01fSNick Piggin */ 2085fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2086c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2087fb1cc555SAl Viro { 2088a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20896c0d46c4SAl Viro struct dentry *dentry; 2090ca344a89SAl Viro int open_flag = op->open_flag; 20916c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2092ca344a89SAl Viro int want_write = 0; 2093bcda7652SAl Viro int acc_mode = op->acc_mode; 2094fb1cc555SAl Viro struct file *filp; 209516c2cd71SAl Viro int error; 2096fb1cc555SAl Viro 2097c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2098c3e380b0SAl Viro nd->flags |= op->intent; 2099c3e380b0SAl Viro 21001f36f774SAl Viro switch (nd->last_type) { 21011f36f774SAl Viro case LAST_DOTDOT: 2102176306f5SNeil Brown case LAST_DOT: 2103fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2104fe2d35ffSAl Viro if (error) 2105fe2d35ffSAl Viro return ERR_PTR(error); 21061f36f774SAl Viro /* fallthrough */ 21071f36f774SAl Viro case LAST_ROOT: 21089f1fafeeSAl Viro error = complete_walk(nd); 210916c2cd71SAl Viro if (error) 21109f1fafeeSAl Viro return ERR_PTR(error); 2111fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2112ca344a89SAl Viro if (open_flag & O_CREAT) { 211316c2cd71SAl Viro error = -EISDIR; 21141f36f774SAl Viro goto exit; 2115fe2d35ffSAl Viro } 2116fe2d35ffSAl Viro goto ok; 21171f36f774SAl Viro case LAST_BIND: 21189f1fafeeSAl Viro error = complete_walk(nd); 211916c2cd71SAl Viro if (error) 21209f1fafeeSAl Viro return ERR_PTR(error); 21211f36f774SAl Viro audit_inode(pathname, dir); 21221f36f774SAl Viro goto ok; 21231f36f774SAl Viro } 2124a2c36b45SAl Viro 2125ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2126bcda7652SAl Viro int symlink_ok = 0; 2127fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2128fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2129bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2130bcda7652SAl Viro symlink_ok = 1; 2131fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2132ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2133ce57dfc1SAl Viro !symlink_ok); 2134ce57dfc1SAl Viro if (error < 0) 2135fe2d35ffSAl Viro return ERR_PTR(error); 2136ce57dfc1SAl Viro if (error) /* symlink */ 2137fe2d35ffSAl Viro return NULL; 2138fe2d35ffSAl Viro /* sayonara */ 21399f1fafeeSAl Viro error = complete_walk(nd); 21409f1fafeeSAl Viro if (error) 2141fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2142fe2d35ffSAl Viro 2143fe2d35ffSAl Viro error = -ENOTDIR; 2144fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2145ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2146fe2d35ffSAl Viro goto exit; 2147fe2d35ffSAl Viro } 2148fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2149fe2d35ffSAl Viro goto ok; 2150fe2d35ffSAl Viro } 2151fe2d35ffSAl Viro 2152fe2d35ffSAl Viro /* create side of things */ 2153a3fbbde7SAl Viro /* 2154a3fbbde7SAl Viro * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been 2155a3fbbde7SAl Viro * cleared when we got to the last component we are about to look up 2156a3fbbde7SAl Viro */ 21579f1fafeeSAl Viro error = complete_walk(nd); 21589f1fafeeSAl Viro if (error) 21599f1fafeeSAl Viro return ERR_PTR(error); 2160fe2d35ffSAl Viro 2161fe2d35ffSAl Viro audit_inode(pathname, dir); 216216c2cd71SAl Viro error = -EISDIR; 21631f36f774SAl Viro /* trailing slashes? */ 216431e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21651f36f774SAl Viro goto exit; 21661f36f774SAl Viro 2167a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2168a1e28038SAl Viro 21696c0d46c4SAl Viro dentry = lookup_hash(nd); 21706c0d46c4SAl Viro error = PTR_ERR(dentry); 21716c0d46c4SAl Viro if (IS_ERR(dentry)) { 2172fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2173fb1cc555SAl Viro goto exit; 2174fb1cc555SAl Viro } 2175fb1cc555SAl Viro 21766c0d46c4SAl Viro path->dentry = dentry; 21776c0d46c4SAl Viro path->mnt = nd->path.mnt; 21786c0d46c4SAl Viro 2179fb1cc555SAl Viro /* Negative dentry, just create the file */ 21806c0d46c4SAl Viro if (!dentry->d_inode) { 2181a218d0fdSAl Viro umode_t mode = op->mode; 21826c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21836c0d46c4SAl Viro mode &= ~current_umask(); 2184fb1cc555SAl Viro /* 2185fb1cc555SAl Viro * This write is needed to ensure that a 21866c0d46c4SAl Viro * rw->ro transition does not occur between 2187fb1cc555SAl Viro * the time when the file is created and when 2188fb1cc555SAl Viro * a permanent write count is taken through 2189fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2190fb1cc555SAl Viro */ 2191fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2192fb1cc555SAl Viro if (error) 2193fb1cc555SAl Viro goto exit_mutex_unlock; 2194ca344a89SAl Viro want_write = 1; 21959b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2196ca344a89SAl Viro open_flag &= ~O_TRUNC; 21976c0d46c4SAl Viro will_truncate = 0; 2198bcda7652SAl Viro acc_mode = MAY_OPEN; 21996c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 22006c0d46c4SAl Viro if (error) 22016c0d46c4SAl Viro goto exit_mutex_unlock; 22026c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 22036c0d46c4SAl Viro if (error) 22046c0d46c4SAl Viro goto exit_mutex_unlock; 22056c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 22066c0d46c4SAl Viro dput(nd->path.dentry); 22076c0d46c4SAl Viro nd->path.dentry = dentry; 2208ca344a89SAl Viro goto common; 2209fb1cc555SAl Viro } 2210fb1cc555SAl Viro 2211fb1cc555SAl Viro /* 2212fb1cc555SAl Viro * It already exists. 2213fb1cc555SAl Viro */ 2214fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2215fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2216fb1cc555SAl Viro 2217fb1cc555SAl Viro error = -EEXIST; 2218ca344a89SAl Viro if (open_flag & O_EXCL) 2219fb1cc555SAl Viro goto exit_dput; 2220fb1cc555SAl Viro 22219875cf80SDavid Howells error = follow_managed(path, nd->flags); 22229875cf80SDavid Howells if (error < 0) 2223fb1cc555SAl Viro goto exit_dput; 2224fb1cc555SAl Viro 2225a3fbbde7SAl Viro if (error) 2226a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2227a3fbbde7SAl Viro 2228fb1cc555SAl Viro error = -ENOENT; 2229fb1cc555SAl Viro if (!path->dentry->d_inode) 2230fb1cc555SAl Viro goto exit_dput; 22319e67f361SAl Viro 22329e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2233fb1cc555SAl Viro return NULL; 2234fb1cc555SAl Viro 2235fb1cc555SAl Viro path_to_nameidata(path, nd); 223631e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2237a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2238a3fbbde7SAl Viro error = complete_walk(nd); 2239a3fbbde7SAl Viro if (error) 2240a3fbbde7SAl Viro goto exit; 2241fb1cc555SAl Viro error = -EISDIR; 224231e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2243fb1cc555SAl Viro goto exit; 224467ee3ad2SAl Viro ok: 22456c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22466c0d46c4SAl Viro will_truncate = 0; 22476c0d46c4SAl Viro 22480f9d1a10SAl Viro if (will_truncate) { 22490f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22500f9d1a10SAl Viro if (error) 22510f9d1a10SAl Viro goto exit; 2252ca344a89SAl Viro want_write = 1; 22530f9d1a10SAl Viro } 2254ca344a89SAl Viro common: 2255bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2256ca344a89SAl Viro if (error) 22570f9d1a10SAl Viro goto exit; 22580f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22590f9d1a10SAl Viro if (!IS_ERR(filp)) { 22600f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22610f9d1a10SAl Viro if (error) { 22620f9d1a10SAl Viro fput(filp); 22630f9d1a10SAl Viro filp = ERR_PTR(error); 22640f9d1a10SAl Viro } 22650f9d1a10SAl Viro } 22660f9d1a10SAl Viro if (!IS_ERR(filp)) { 22670f9d1a10SAl Viro if (will_truncate) { 22680f9d1a10SAl Viro error = handle_truncate(filp); 22690f9d1a10SAl Viro if (error) { 22700f9d1a10SAl Viro fput(filp); 22710f9d1a10SAl Viro filp = ERR_PTR(error); 22720f9d1a10SAl Viro } 22730f9d1a10SAl Viro } 22740f9d1a10SAl Viro } 2275ca344a89SAl Viro out: 2276ca344a89SAl Viro if (want_write) 22770f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22780f9d1a10SAl Viro path_put(&nd->path); 2279fb1cc555SAl Viro return filp; 2280fb1cc555SAl Viro 2281fb1cc555SAl Viro exit_mutex_unlock: 2282fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2283fb1cc555SAl Viro exit_dput: 2284fb1cc555SAl Viro path_put_conditional(path, nd); 2285fb1cc555SAl Viro exit: 2286ca344a89SAl Viro filp = ERR_PTR(error); 2287ca344a89SAl Viro goto out; 2288fb1cc555SAl Viro } 2289fb1cc555SAl Viro 229013aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 229173d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22921da177e4SLinus Torvalds { 2293fe2d35ffSAl Viro struct file *base = NULL; 22944a3fd211SDave Hansen struct file *filp; 22959850c056SAl Viro struct path path; 229613aab428SAl Viro int error; 229731e6b01fSNick Piggin 229831e6b01fSNick Piggin filp = get_empty_filp(); 229931e6b01fSNick Piggin if (!filp) 230031e6b01fSNick Piggin return ERR_PTR(-ENFILE); 230131e6b01fSNick Piggin 230247c805dcSAl Viro filp->f_flags = op->open_flag; 230373d049a4SAl Viro nd->intent.open.file = filp; 230473d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 230573d049a4SAl Viro nd->intent.open.create_mode = op->mode; 230631e6b01fSNick Piggin 230773d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 230831e6b01fSNick Piggin if (unlikely(error)) 230913aab428SAl Viro goto out_filp; 231031e6b01fSNick Piggin 2311fe2d35ffSAl Viro current->total_link_count = 0; 231273d049a4SAl Viro error = link_path_walk(pathname, nd); 231331e6b01fSNick Piggin if (unlikely(error)) 231431e6b01fSNick Piggin goto out_filp; 23151da177e4SLinus Torvalds 231673d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2317806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 23187b9337aaSNick Piggin struct path link = path; 2319def4af30SAl Viro void *cookie; 2320574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 232173d049a4SAl Viro path_put_conditional(&path, nd); 232273d049a4SAl Viro path_put(&nd->path); 232340b39136SAl Viro filp = ERR_PTR(-ELOOP); 232440b39136SAl Viro break; 232540b39136SAl Viro } 232673d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 232773d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2328574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2329c3e380b0SAl Viro if (unlikely(error)) 2330f1afe9efSAl Viro filp = ERR_PTR(error); 2331c3e380b0SAl Viro else 233273d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2333574197e0SAl Viro put_link(nd, &link, cookie); 2334806b681cSAl Viro } 233510fa8e62SAl Viro out: 233673d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 233773d049a4SAl Viro path_put(&nd->root); 2338fe2d35ffSAl Viro if (base) 2339fe2d35ffSAl Viro fput(base); 234073d049a4SAl Viro release_open_intent(nd); 234110fa8e62SAl Viro return filp; 23421da177e4SLinus Torvalds 234331e6b01fSNick Piggin out_filp: 234410fa8e62SAl Viro filp = ERR_PTR(error); 234510fa8e62SAl Viro goto out; 2346de459215SKirill Korotaev } 23471da177e4SLinus Torvalds 234813aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 234913aab428SAl Viro const struct open_flags *op, int flags) 235013aab428SAl Viro { 235173d049a4SAl Viro struct nameidata nd; 235213aab428SAl Viro struct file *filp; 235313aab428SAl Viro 235473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 235513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 235673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 235713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 235873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 235913aab428SAl Viro return filp; 236013aab428SAl Viro } 236113aab428SAl Viro 236273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 236373d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 236473d049a4SAl Viro { 236573d049a4SAl Viro struct nameidata nd; 236673d049a4SAl Viro struct file *file; 236773d049a4SAl Viro 236873d049a4SAl Viro nd.root.mnt = mnt; 236973d049a4SAl Viro nd.root.dentry = dentry; 237073d049a4SAl Viro 237173d049a4SAl Viro flags |= LOOKUP_ROOT; 237273d049a4SAl Viro 2373bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 237473d049a4SAl Viro return ERR_PTR(-ELOOP); 237573d049a4SAl Viro 237673d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 237773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 237873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 237973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 238073d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 238173d049a4SAl Viro return file; 238273d049a4SAl Viro } 238373d049a4SAl Viro 2384ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 23851da177e4SLinus Torvalds { 2386c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2387ed75e95dSAl Viro struct nameidata nd; 2388ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2389ed75e95dSAl Viro if (error) 2390ed75e95dSAl Viro return ERR_PTR(error); 23911da177e4SLinus Torvalds 2392c663e5d8SChristoph Hellwig /* 2393c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2394c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2395c663e5d8SChristoph Hellwig */ 2396ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2397ed75e95dSAl Viro goto out; 2398ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2399ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2400ed75e95dSAl Viro nd.intent.open.flags = O_EXCL; 2401c663e5d8SChristoph Hellwig 2402c663e5d8SChristoph Hellwig /* 2403c663e5d8SChristoph Hellwig * Do the final lookup. 2404c663e5d8SChristoph Hellwig */ 2405ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2406ed75e95dSAl Viro dentry = lookup_hash(&nd); 24071da177e4SLinus Torvalds if (IS_ERR(dentry)) 24081da177e4SLinus Torvalds goto fail; 2409c663e5d8SChristoph Hellwig 2410e9baf6e5SAl Viro if (dentry->d_inode) 2411e9baf6e5SAl Viro goto eexist; 2412c663e5d8SChristoph Hellwig /* 2413c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2414c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2415c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2416c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2417c663e5d8SChristoph Hellwig */ 2418ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 24191da177e4SLinus Torvalds dput(dentry); 24201da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2421ed75e95dSAl Viro goto fail; 2422e9baf6e5SAl Viro } 2423ed75e95dSAl Viro *path = nd.path; 2424e9baf6e5SAl Viro return dentry; 2425e9baf6e5SAl Viro eexist: 2426e9baf6e5SAl Viro dput(dentry); 2427e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 24281da177e4SLinus Torvalds fail: 2429dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2430ed75e95dSAl Viro out: 2431dae6ad8fSAl Viro path_put(&nd.path); 2432ed75e95dSAl Viro return dentry; 2433dae6ad8fSAl Viro } 2434dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2435dae6ad8fSAl Viro 2436dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2437dae6ad8fSAl Viro { 2438dae6ad8fSAl Viro char *tmp = getname(pathname); 2439dae6ad8fSAl Viro struct dentry *res; 2440dae6ad8fSAl Viro if (IS_ERR(tmp)) 2441dae6ad8fSAl Viro return ERR_CAST(tmp); 2442dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2443dae6ad8fSAl Viro putname(tmp); 2444dae6ad8fSAl Viro return res; 2445dae6ad8fSAl Viro } 2446dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2447dae6ad8fSAl Viro 24481a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 24491da177e4SLinus Torvalds { 2450a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24511da177e4SLinus Torvalds 24521da177e4SLinus Torvalds if (error) 24531da177e4SLinus Torvalds return error; 24541da177e4SLinus Torvalds 2455e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2456e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 24571da177e4SLinus Torvalds return -EPERM; 24581da177e4SLinus Torvalds 2459acfa4380SAl Viro if (!dir->i_op->mknod) 24601da177e4SLinus Torvalds return -EPERM; 24611da177e4SLinus Torvalds 246208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 246308ce5f16SSerge E. Hallyn if (error) 246408ce5f16SSerge E. Hallyn return error; 246508ce5f16SSerge E. Hallyn 24661da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24671da177e4SLinus Torvalds if (error) 24681da177e4SLinus Torvalds return error; 24691da177e4SLinus Torvalds 24701da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2471a74574aaSStephen Smalley if (!error) 2472f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24731da177e4SLinus Torvalds return error; 24741da177e4SLinus Torvalds } 24751da177e4SLinus Torvalds 2476f69aac00SAl Viro static int may_mknod(umode_t mode) 2477463c3197SDave Hansen { 2478463c3197SDave Hansen switch (mode & S_IFMT) { 2479463c3197SDave Hansen case S_IFREG: 2480463c3197SDave Hansen case S_IFCHR: 2481463c3197SDave Hansen case S_IFBLK: 2482463c3197SDave Hansen case S_IFIFO: 2483463c3197SDave Hansen case S_IFSOCK: 2484463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2485463c3197SDave Hansen return 0; 2486463c3197SDave Hansen case S_IFDIR: 2487463c3197SDave Hansen return -EPERM; 2488463c3197SDave Hansen default: 2489463c3197SDave Hansen return -EINVAL; 2490463c3197SDave Hansen } 2491463c3197SDave Hansen } 2492463c3197SDave Hansen 24938208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 24942e4d0924SHeiko Carstens unsigned, dev) 24951da177e4SLinus Torvalds { 24961da177e4SLinus Torvalds struct dentry *dentry; 2497dae6ad8fSAl Viro struct path path; 2498dae6ad8fSAl Viro int error; 24991da177e4SLinus Torvalds 25001da177e4SLinus Torvalds if (S_ISDIR(mode)) 25011da177e4SLinus Torvalds return -EPERM; 25021da177e4SLinus Torvalds 2503dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2504dae6ad8fSAl Viro if (IS_ERR(dentry)) 2505dae6ad8fSAl Viro return PTR_ERR(dentry); 25062ad94ae6SAl Viro 2507dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2508ce3b0f8dSAl Viro mode &= ~current_umask(); 2509463c3197SDave Hansen error = may_mknod(mode); 2510463c3197SDave Hansen if (error) 2511463c3197SDave Hansen goto out_dput; 2512dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2513463c3197SDave Hansen if (error) 2514463c3197SDave Hansen goto out_dput; 2515dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2516be6d3e56SKentaro Takeda if (error) 2517be6d3e56SKentaro Takeda goto out_drop_write; 25181da177e4SLinus Torvalds switch (mode & S_IFMT) { 25191da177e4SLinus Torvalds case 0: case S_IFREG: 2520dae6ad8fSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); 25211da177e4SLinus Torvalds break; 25221da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2523dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 25241da177e4SLinus Torvalds new_decode_dev(dev)); 25251da177e4SLinus Torvalds break; 25261da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2527dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 25281da177e4SLinus Torvalds break; 25291da177e4SLinus Torvalds } 2530be6d3e56SKentaro Takeda out_drop_write: 2531dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2532463c3197SDave Hansen out_dput: 25331da177e4SLinus Torvalds dput(dentry); 2534dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2535dae6ad8fSAl Viro path_put(&path); 25361da177e4SLinus Torvalds 25371da177e4SLinus Torvalds return error; 25381da177e4SLinus Torvalds } 25391da177e4SLinus Torvalds 25408208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 25415590ff0dSUlrich Drepper { 25425590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25435590ff0dSUlrich Drepper } 25445590ff0dSUlrich Drepper 254518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 25461da177e4SLinus Torvalds { 2547a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25481da177e4SLinus Torvalds 25491da177e4SLinus Torvalds if (error) 25501da177e4SLinus Torvalds return error; 25511da177e4SLinus Torvalds 2552acfa4380SAl Viro if (!dir->i_op->mkdir) 25531da177e4SLinus Torvalds return -EPERM; 25541da177e4SLinus Torvalds 25551da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25561da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25571da177e4SLinus Torvalds if (error) 25581da177e4SLinus Torvalds return error; 25591da177e4SLinus Torvalds 25601da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2561a74574aaSStephen Smalley if (!error) 2562f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25631da177e4SLinus Torvalds return error; 25641da177e4SLinus Torvalds } 25651da177e4SLinus Torvalds 2566a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 25671da177e4SLinus Torvalds { 25686902d925SDave Hansen struct dentry *dentry; 2569dae6ad8fSAl Viro struct path path; 2570dae6ad8fSAl Viro int error; 25711da177e4SLinus Torvalds 2572dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 25736902d925SDave Hansen if (IS_ERR(dentry)) 2574dae6ad8fSAl Viro return PTR_ERR(dentry); 25756902d925SDave Hansen 2576dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2577ce3b0f8dSAl Viro mode &= ~current_umask(); 2578dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2579463c3197SDave Hansen if (error) 2580463c3197SDave Hansen goto out_dput; 2581dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 2582be6d3e56SKentaro Takeda if (error) 2583be6d3e56SKentaro Takeda goto out_drop_write; 2584dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 2585be6d3e56SKentaro Takeda out_drop_write: 2586dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2587463c3197SDave Hansen out_dput: 25881da177e4SLinus Torvalds dput(dentry); 2589dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2590dae6ad8fSAl Viro path_put(&path); 25911da177e4SLinus Torvalds return error; 25921da177e4SLinus Torvalds } 25931da177e4SLinus Torvalds 2594a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 25955590ff0dSUlrich Drepper { 25965590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25975590ff0dSUlrich Drepper } 25985590ff0dSUlrich Drepper 25991da177e4SLinus Torvalds /* 2600a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2601a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2602a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2603a71905f0SSage Weil * then we drop the dentry now. 26041da177e4SLinus Torvalds * 26051da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 26061da177e4SLinus Torvalds * do a 26071da177e4SLinus Torvalds * 26081da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 26091da177e4SLinus Torvalds * return -EBUSY; 26101da177e4SLinus Torvalds * 26111da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 26121da177e4SLinus Torvalds * that is still in use by something else.. 26131da177e4SLinus Torvalds */ 26141da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 26151da177e4SLinus Torvalds { 26161da177e4SLinus Torvalds shrink_dcache_parent(dentry); 26171da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 261864252c75SSage Weil if (dentry->d_count == 1) 26191da177e4SLinus Torvalds __d_drop(dentry); 26201da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 26211da177e4SLinus Torvalds } 26221da177e4SLinus Torvalds 26231da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 26241da177e4SLinus Torvalds { 26251da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26261da177e4SLinus Torvalds 26271da177e4SLinus Torvalds if (error) 26281da177e4SLinus Torvalds return error; 26291da177e4SLinus Torvalds 2630acfa4380SAl Viro if (!dir->i_op->rmdir) 26311da177e4SLinus Torvalds return -EPERM; 26321da177e4SLinus Torvalds 26331d2ef590SAl Viro dget(dentry); 26341b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2635912dbc15SSage Weil 26361da177e4SLinus Torvalds error = -EBUSY; 2637912dbc15SSage Weil if (d_mountpoint(dentry)) 2638912dbc15SSage Weil goto out; 2639912dbc15SSage Weil 26401da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2641912dbc15SSage Weil if (error) 2642912dbc15SSage Weil goto out; 2643912dbc15SSage Weil 26443cebde24SSage Weil shrink_dcache_parent(dentry); 26451da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2646912dbc15SSage Weil if (error) 2647912dbc15SSage Weil goto out; 2648912dbc15SSage Weil 26491da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2650d83c49f3SAl Viro dont_mount(dentry); 26511da177e4SLinus Torvalds 2652912dbc15SSage Weil out: 2653912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 26541d2ef590SAl Viro dput(dentry); 2655912dbc15SSage Weil if (!error) 2656912dbc15SSage Weil d_delete(dentry); 26571da177e4SLinus Torvalds return error; 26581da177e4SLinus Torvalds } 26591da177e4SLinus Torvalds 26605590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26611da177e4SLinus Torvalds { 26621da177e4SLinus Torvalds int error = 0; 26631da177e4SLinus Torvalds char * name; 26641da177e4SLinus Torvalds struct dentry *dentry; 26651da177e4SLinus Torvalds struct nameidata nd; 26661da177e4SLinus Torvalds 26672ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26681da177e4SLinus Torvalds if (error) 26692ad94ae6SAl Viro return error; 26701da177e4SLinus Torvalds 26711da177e4SLinus Torvalds switch(nd.last_type) { 26721da177e4SLinus Torvalds case LAST_DOTDOT: 26731da177e4SLinus Torvalds error = -ENOTEMPTY; 26741da177e4SLinus Torvalds goto exit1; 26751da177e4SLinus Torvalds case LAST_DOT: 26761da177e4SLinus Torvalds error = -EINVAL; 26771da177e4SLinus Torvalds goto exit1; 26781da177e4SLinus Torvalds case LAST_ROOT: 26791da177e4SLinus Torvalds error = -EBUSY; 26801da177e4SLinus Torvalds goto exit1; 26811da177e4SLinus Torvalds } 26820612d9fbSOGAWA Hirofumi 26830612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26840612d9fbSOGAWA Hirofumi 26854ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 268649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26871da177e4SLinus Torvalds error = PTR_ERR(dentry); 26886902d925SDave Hansen if (IS_ERR(dentry)) 26896902d925SDave Hansen goto exit2; 2690e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2691e6bc45d6STheodore Ts'o error = -ENOENT; 2692e6bc45d6STheodore Ts'o goto exit3; 2693e6bc45d6STheodore Ts'o } 26940622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26950622753bSDave Hansen if (error) 26960622753bSDave Hansen goto exit3; 2697be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2698be6d3e56SKentaro Takeda if (error) 2699be6d3e56SKentaro Takeda goto exit4; 27004ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2701be6d3e56SKentaro Takeda exit4: 27020622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27030622753bSDave Hansen exit3: 27041da177e4SLinus Torvalds dput(dentry); 27056902d925SDave Hansen exit2: 27064ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27071da177e4SLinus Torvalds exit1: 27081d957f9bSJan Blunck path_put(&nd.path); 27091da177e4SLinus Torvalds putname(name); 27101da177e4SLinus Torvalds return error; 27111da177e4SLinus Torvalds } 27121da177e4SLinus Torvalds 27133cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 27145590ff0dSUlrich Drepper { 27155590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 27165590ff0dSUlrich Drepper } 27175590ff0dSUlrich Drepper 27181da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 27191da177e4SLinus Torvalds { 27201da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds if (error) 27231da177e4SLinus Torvalds return error; 27241da177e4SLinus Torvalds 2725acfa4380SAl Viro if (!dir->i_op->unlink) 27261da177e4SLinus Torvalds return -EPERM; 27271da177e4SLinus Torvalds 27281b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 27291da177e4SLinus Torvalds if (d_mountpoint(dentry)) 27301da177e4SLinus Torvalds error = -EBUSY; 27311da177e4SLinus Torvalds else { 27321da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2733bec1052eSAl Viro if (!error) { 27341da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2735bec1052eSAl Viro if (!error) 2736d83c49f3SAl Viro dont_mount(dentry); 2737bec1052eSAl Viro } 27381da177e4SLinus Torvalds } 27391b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27401da177e4SLinus Torvalds 27411da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27421da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2743ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27441da177e4SLinus Torvalds d_delete(dentry); 27451da177e4SLinus Torvalds } 27460eeca283SRobert Love 27471da177e4SLinus Torvalds return error; 27481da177e4SLinus Torvalds } 27491da177e4SLinus Torvalds 27501da177e4SLinus Torvalds /* 27511da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27521b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27531da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27541da177e4SLinus Torvalds * while waiting on the I/O. 27551da177e4SLinus Torvalds */ 27565590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27571da177e4SLinus Torvalds { 27582ad94ae6SAl Viro int error; 27591da177e4SLinus Torvalds char *name; 27601da177e4SLinus Torvalds struct dentry *dentry; 27611da177e4SLinus Torvalds struct nameidata nd; 27621da177e4SLinus Torvalds struct inode *inode = NULL; 27631da177e4SLinus Torvalds 27642ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27651da177e4SLinus Torvalds if (error) 27662ad94ae6SAl Viro return error; 27672ad94ae6SAl Viro 27681da177e4SLinus Torvalds error = -EISDIR; 27691da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27701da177e4SLinus Torvalds goto exit1; 27710612d9fbSOGAWA Hirofumi 27720612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27730612d9fbSOGAWA Hirofumi 27744ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 277549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27761da177e4SLinus Torvalds error = PTR_ERR(dentry); 27771da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27781da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 277950338b88STörök Edwin if (nd.last.name[nd.last.len]) 278050338b88STörök Edwin goto slashes; 27811da177e4SLinus Torvalds inode = dentry->d_inode; 278250338b88STörök Edwin if (!inode) 2783e6bc45d6STheodore Ts'o goto slashes; 27847de9c6eeSAl Viro ihold(inode); 27850622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27860622753bSDave Hansen if (error) 27870622753bSDave Hansen goto exit2; 2788be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2789be6d3e56SKentaro Takeda if (error) 2790be6d3e56SKentaro Takeda goto exit3; 27914ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2792be6d3e56SKentaro Takeda exit3: 27930622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27941da177e4SLinus Torvalds exit2: 27951da177e4SLinus Torvalds dput(dentry); 27961da177e4SLinus Torvalds } 27974ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27981da177e4SLinus Torvalds if (inode) 27991da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 28001da177e4SLinus Torvalds exit1: 28011d957f9bSJan Blunck path_put(&nd.path); 28021da177e4SLinus Torvalds putname(name); 28031da177e4SLinus Torvalds return error; 28041da177e4SLinus Torvalds 28051da177e4SLinus Torvalds slashes: 28061da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 28071da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 28081da177e4SLinus Torvalds goto exit2; 28091da177e4SLinus Torvalds } 28101da177e4SLinus Torvalds 28112e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 28125590ff0dSUlrich Drepper { 28135590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 28145590ff0dSUlrich Drepper return -EINVAL; 28155590ff0dSUlrich Drepper 28165590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 28175590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 28185590ff0dSUlrich Drepper 28195590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 28205590ff0dSUlrich Drepper } 28215590ff0dSUlrich Drepper 28223480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 28235590ff0dSUlrich Drepper { 28245590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 28255590ff0dSUlrich Drepper } 28265590ff0dSUlrich Drepper 2827db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 28281da177e4SLinus Torvalds { 2829a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28301da177e4SLinus Torvalds 28311da177e4SLinus Torvalds if (error) 28321da177e4SLinus Torvalds return error; 28331da177e4SLinus Torvalds 2834acfa4380SAl Viro if (!dir->i_op->symlink) 28351da177e4SLinus Torvalds return -EPERM; 28361da177e4SLinus Torvalds 28371da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28381da177e4SLinus Torvalds if (error) 28391da177e4SLinus Torvalds return error; 28401da177e4SLinus Torvalds 28411da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2842a74574aaSStephen Smalley if (!error) 2843f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28441da177e4SLinus Torvalds return error; 28451da177e4SLinus Torvalds } 28461da177e4SLinus Torvalds 28472e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28482e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28491da177e4SLinus Torvalds { 28502ad94ae6SAl Viro int error; 28511da177e4SLinus Torvalds char *from; 28526902d925SDave Hansen struct dentry *dentry; 2853dae6ad8fSAl Viro struct path path; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds from = getname(oldname); 28561da177e4SLinus Torvalds if (IS_ERR(from)) 28571da177e4SLinus Torvalds return PTR_ERR(from); 28582ad94ae6SAl Viro 2859dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 28601da177e4SLinus Torvalds error = PTR_ERR(dentry); 28616902d925SDave Hansen if (IS_ERR(dentry)) 2862dae6ad8fSAl Viro goto out_putname; 28636902d925SDave Hansen 2864dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 286575c3f29dSDave Hansen if (error) 286675c3f29dSDave Hansen goto out_dput; 2867dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 2868be6d3e56SKentaro Takeda if (error) 2869be6d3e56SKentaro Takeda goto out_drop_write; 2870dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 2871be6d3e56SKentaro Takeda out_drop_write: 2872dae6ad8fSAl Viro mnt_drop_write(path.mnt); 287375c3f29dSDave Hansen out_dput: 28741da177e4SLinus Torvalds dput(dentry); 2875dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2876dae6ad8fSAl Viro path_put(&path); 28776902d925SDave Hansen out_putname: 28781da177e4SLinus Torvalds putname(from); 28791da177e4SLinus Torvalds return error; 28801da177e4SLinus Torvalds } 28811da177e4SLinus Torvalds 28823480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28835590ff0dSUlrich Drepper { 28845590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28855590ff0dSUlrich Drepper } 28865590ff0dSUlrich Drepper 28871da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28881da177e4SLinus Torvalds { 28891da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28901da177e4SLinus Torvalds int error; 28911da177e4SLinus Torvalds 28921da177e4SLinus Torvalds if (!inode) 28931da177e4SLinus Torvalds return -ENOENT; 28941da177e4SLinus Torvalds 2895a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28961da177e4SLinus Torvalds if (error) 28971da177e4SLinus Torvalds return error; 28981da177e4SLinus Torvalds 28991da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 29001da177e4SLinus Torvalds return -EXDEV; 29011da177e4SLinus Torvalds 29021da177e4SLinus Torvalds /* 29031da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 29041da177e4SLinus Torvalds */ 29051da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 29061da177e4SLinus Torvalds return -EPERM; 2907acfa4380SAl Viro if (!dir->i_op->link) 29081da177e4SLinus Torvalds return -EPERM; 29097e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 29101da177e4SLinus Torvalds return -EPERM; 29111da177e4SLinus Torvalds 29121da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 29131da177e4SLinus Torvalds if (error) 29141da177e4SLinus Torvalds return error; 29151da177e4SLinus Torvalds 29167e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2917aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2918aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2919aae8a97dSAneesh Kumar K.V error = -ENOENT; 2920aae8a97dSAneesh Kumar K.V else 29211da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 29227e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2923e31e14ecSStephen Smalley if (!error) 29247e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 29251da177e4SLinus Torvalds return error; 29261da177e4SLinus Torvalds } 29271da177e4SLinus Torvalds 29281da177e4SLinus Torvalds /* 29291da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29301da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29311da177e4SLinus Torvalds * newname. --KAB 29321da177e4SLinus Torvalds * 29331da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29341da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29351da177e4SLinus Torvalds * and other special files. --ADM 29361da177e4SLinus Torvalds */ 29372e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29382e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29391da177e4SLinus Torvalds { 29401da177e4SLinus Torvalds struct dentry *new_dentry; 2941dae6ad8fSAl Viro struct path old_path, new_path; 294211a7b371SAneesh Kumar K.V int how = 0; 29431da177e4SLinus Torvalds int error; 29441da177e4SLinus Torvalds 294511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2946c04030e1SUlrich Drepper return -EINVAL; 294711a7b371SAneesh Kumar K.V /* 294811a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 294911a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 295011a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 295111a7b371SAneesh Kumar K.V */ 295211a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 295311a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 295411a7b371SAneesh Kumar K.V return -ENOENT; 295511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 295611a7b371SAneesh Kumar K.V } 2957c04030e1SUlrich Drepper 295811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 295911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 296011a7b371SAneesh Kumar K.V 296111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29621da177e4SLinus Torvalds if (error) 29632ad94ae6SAl Viro return error; 29642ad94ae6SAl Viro 2965dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 29661da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29676902d925SDave Hansen if (IS_ERR(new_dentry)) 2968dae6ad8fSAl Viro goto out; 2969dae6ad8fSAl Viro 2970dae6ad8fSAl Viro error = -EXDEV; 2971dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 2972dae6ad8fSAl Viro goto out_dput; 2973dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 297475c3f29dSDave Hansen if (error) 297575c3f29dSDave Hansen goto out_dput; 2976dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 2977be6d3e56SKentaro Takeda if (error) 2978be6d3e56SKentaro Takeda goto out_drop_write; 2979dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 2980be6d3e56SKentaro Takeda out_drop_write: 2981dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 298275c3f29dSDave Hansen out_dput: 29831da177e4SLinus Torvalds dput(new_dentry); 2984dae6ad8fSAl Viro mutex_unlock(&new_path.dentry->d_inode->i_mutex); 2985dae6ad8fSAl Viro path_put(&new_path); 29861da177e4SLinus Torvalds out: 29872d8f3038SAl Viro path_put(&old_path); 29881da177e4SLinus Torvalds 29891da177e4SLinus Torvalds return error; 29901da177e4SLinus Torvalds } 29911da177e4SLinus Torvalds 29923480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29935590ff0dSUlrich Drepper { 2994c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29955590ff0dSUlrich Drepper } 29965590ff0dSUlrich Drepper 29971da177e4SLinus Torvalds /* 29981da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29991da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 30001da177e4SLinus Torvalds * Problems: 30011da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 30021da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 30031da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3004a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 30051da177e4SLinus Torvalds * story. 30061da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 30071b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 30081da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 30091da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3010a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 30111da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 30121da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 30131da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3014a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 30151da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 30161da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 30171da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3018e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 30191b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 30201da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3021c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 30221da177e4SLinus Torvalds * locking]. 30231da177e4SLinus Torvalds */ 302475c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30251da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30261da177e4SLinus Torvalds { 30271da177e4SLinus Torvalds int error = 0; 30289055cba7SSage Weil struct inode *target = new_dentry->d_inode; 30291da177e4SLinus Torvalds 30301da177e4SLinus Torvalds /* 30311da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30321da177e4SLinus Torvalds * we'll need to flip '..'. 30331da177e4SLinus Torvalds */ 30341da177e4SLinus Torvalds if (new_dir != old_dir) { 3035f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30361da177e4SLinus Torvalds if (error) 30371da177e4SLinus Torvalds return error; 30381da177e4SLinus Torvalds } 30391da177e4SLinus Torvalds 30401da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30411da177e4SLinus Torvalds if (error) 30421da177e4SLinus Torvalds return error; 30431da177e4SLinus Torvalds 30441d2ef590SAl Viro dget(new_dentry); 3045d83c49f3SAl Viro if (target) 30461b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30479055cba7SSage Weil 30481da177e4SLinus Torvalds error = -EBUSY; 30499055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 30509055cba7SSage Weil goto out; 30519055cba7SSage Weil 30523cebde24SSage Weil if (target) 30533cebde24SSage Weil shrink_dcache_parent(new_dentry); 30541da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30559055cba7SSage Weil if (error) 30569055cba7SSage Weil goto out; 30579055cba7SSage Weil 30581da177e4SLinus Torvalds if (target) { 30591da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3060d83c49f3SAl Viro dont_mount(new_dentry); 3061d83c49f3SAl Viro } 30629055cba7SSage Weil out: 30639055cba7SSage Weil if (target) 30641b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30651d2ef590SAl Viro dput(new_dentry); 3066e31e14ecSStephen Smalley if (!error) 3067349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30681da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30691da177e4SLinus Torvalds return error; 30701da177e4SLinus Torvalds } 30711da177e4SLinus Torvalds 307275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30731da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30741da177e4SLinus Torvalds { 307551892bbbSSage Weil struct inode *target = new_dentry->d_inode; 30761da177e4SLinus Torvalds int error; 30771da177e4SLinus Torvalds 30781da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30791da177e4SLinus Torvalds if (error) 30801da177e4SLinus Torvalds return error; 30811da177e4SLinus Torvalds 30821da177e4SLinus Torvalds dget(new_dentry); 30831da177e4SLinus Torvalds if (target) 30841b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 308551892bbbSSage Weil 30861da177e4SLinus Torvalds error = -EBUSY; 308751892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 308851892bbbSSage Weil goto out; 308951892bbbSSage Weil 30901da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 309151892bbbSSage Weil if (error) 309251892bbbSSage Weil goto out; 309351892bbbSSage Weil 3094bec1052eSAl Viro if (target) 3095d83c49f3SAl Viro dont_mount(new_dentry); 3096349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30971da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 309851892bbbSSage Weil out: 30991da177e4SLinus Torvalds if (target) 31001b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 31011da177e4SLinus Torvalds dput(new_dentry); 31021da177e4SLinus Torvalds return error; 31031da177e4SLinus Torvalds } 31041da177e4SLinus Torvalds 31051da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 31061da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31071da177e4SLinus Torvalds { 31081da177e4SLinus Torvalds int error; 31091da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 311059b0df21SEric Paris const unsigned char *old_name; 31111da177e4SLinus Torvalds 31121da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 31131da177e4SLinus Torvalds return 0; 31141da177e4SLinus Torvalds 31151da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 31161da177e4SLinus Torvalds if (error) 31171da177e4SLinus Torvalds return error; 31181da177e4SLinus Torvalds 31191da177e4SLinus Torvalds if (!new_dentry->d_inode) 3120a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 31211da177e4SLinus Torvalds else 31221da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31231da177e4SLinus Torvalds if (error) 31241da177e4SLinus Torvalds return error; 31251da177e4SLinus Torvalds 3126acfa4380SAl Viro if (!old_dir->i_op->rename) 31271da177e4SLinus Torvalds return -EPERM; 31281da177e4SLinus Torvalds 31290eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31300eeca283SRobert Love 31311da177e4SLinus Torvalds if (is_dir) 31321da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31331da177e4SLinus Torvalds else 31341da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3135123df294SAl Viro if (!error) 3136123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31375a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31380eeca283SRobert Love fsnotify_oldname_free(old_name); 31390eeca283SRobert Love 31401da177e4SLinus Torvalds return error; 31411da177e4SLinus Torvalds } 31421da177e4SLinus Torvalds 31432e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31442e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31451da177e4SLinus Torvalds { 31461da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31471da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31481da177e4SLinus Torvalds struct dentry *trap; 31491da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31502ad94ae6SAl Viro char *from; 31512ad94ae6SAl Viro char *to; 31522ad94ae6SAl Viro int error; 31531da177e4SLinus Torvalds 31542ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31551da177e4SLinus Torvalds if (error) 31561da177e4SLinus Torvalds goto exit; 31571da177e4SLinus Torvalds 31582ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31591da177e4SLinus Torvalds if (error) 31601da177e4SLinus Torvalds goto exit1; 31611da177e4SLinus Torvalds 31621da177e4SLinus Torvalds error = -EXDEV; 31634ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31641da177e4SLinus Torvalds goto exit2; 31651da177e4SLinus Torvalds 31664ac91378SJan Blunck old_dir = oldnd.path.dentry; 31671da177e4SLinus Torvalds error = -EBUSY; 31681da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31691da177e4SLinus Torvalds goto exit2; 31701da177e4SLinus Torvalds 31714ac91378SJan Blunck new_dir = newnd.path.dentry; 31721da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31731da177e4SLinus Torvalds goto exit2; 31741da177e4SLinus Torvalds 31750612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31760612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31774e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31780612d9fbSOGAWA Hirofumi 31791da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31801da177e4SLinus Torvalds 318149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31821da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31831da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31841da177e4SLinus Torvalds goto exit3; 31851da177e4SLinus Torvalds /* source must exist */ 31861da177e4SLinus Torvalds error = -ENOENT; 31871da177e4SLinus Torvalds if (!old_dentry->d_inode) 31881da177e4SLinus Torvalds goto exit4; 31891da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31901da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31911da177e4SLinus Torvalds error = -ENOTDIR; 31921da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31931da177e4SLinus Torvalds goto exit4; 31941da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31951da177e4SLinus Torvalds goto exit4; 31961da177e4SLinus Torvalds } 31971da177e4SLinus Torvalds /* source should not be ancestor of target */ 31981da177e4SLinus Torvalds error = -EINVAL; 31991da177e4SLinus Torvalds if (old_dentry == trap) 32001da177e4SLinus Torvalds goto exit4; 320149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 32021da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 32031da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 32041da177e4SLinus Torvalds goto exit4; 32051da177e4SLinus Torvalds /* target should not be an ancestor of source */ 32061da177e4SLinus Torvalds error = -ENOTEMPTY; 32071da177e4SLinus Torvalds if (new_dentry == trap) 32081da177e4SLinus Torvalds goto exit5; 32091da177e4SLinus Torvalds 32109079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 32119079b1ebSDave Hansen if (error) 32129079b1ebSDave Hansen goto exit5; 3213be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3214be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3215be6d3e56SKentaro Takeda if (error) 3216be6d3e56SKentaro Takeda goto exit6; 32171da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 32181da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3219be6d3e56SKentaro Takeda exit6: 32209079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 32211da177e4SLinus Torvalds exit5: 32221da177e4SLinus Torvalds dput(new_dentry); 32231da177e4SLinus Torvalds exit4: 32241da177e4SLinus Torvalds dput(old_dentry); 32251da177e4SLinus Torvalds exit3: 32261da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32271da177e4SLinus Torvalds exit2: 32281d957f9bSJan Blunck path_put(&newnd.path); 32292ad94ae6SAl Viro putname(to); 32301da177e4SLinus Torvalds exit1: 32311d957f9bSJan Blunck path_put(&oldnd.path); 32321da177e4SLinus Torvalds putname(from); 32332ad94ae6SAl Viro exit: 32341da177e4SLinus Torvalds return error; 32351da177e4SLinus Torvalds } 32361da177e4SLinus Torvalds 3237a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32385590ff0dSUlrich Drepper { 32395590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32405590ff0dSUlrich Drepper } 32415590ff0dSUlrich Drepper 32421da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32431da177e4SLinus Torvalds { 32441da177e4SLinus Torvalds int len; 32451da177e4SLinus Torvalds 32461da177e4SLinus Torvalds len = PTR_ERR(link); 32471da177e4SLinus Torvalds if (IS_ERR(link)) 32481da177e4SLinus Torvalds goto out; 32491da177e4SLinus Torvalds 32501da177e4SLinus Torvalds len = strlen(link); 32511da177e4SLinus Torvalds if (len > (unsigned) buflen) 32521da177e4SLinus Torvalds len = buflen; 32531da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32541da177e4SLinus Torvalds len = -EFAULT; 32551da177e4SLinus Torvalds out: 32561da177e4SLinus Torvalds return len; 32571da177e4SLinus Torvalds } 32581da177e4SLinus Torvalds 32591da177e4SLinus Torvalds /* 32601da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32611da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32621da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32631da177e4SLinus Torvalds */ 32641da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32651da177e4SLinus Torvalds { 32661da177e4SLinus Torvalds struct nameidata nd; 3267cc314eefSLinus Torvalds void *cookie; 3268694a1764SMarcin Slusarz int res; 3269cc314eefSLinus Torvalds 32701da177e4SLinus Torvalds nd.depth = 0; 3271cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3272694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3273694a1764SMarcin Slusarz return PTR_ERR(cookie); 3274694a1764SMarcin Slusarz 3275694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32761da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3277cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3278694a1764SMarcin Slusarz return res; 32791da177e4SLinus Torvalds } 32801da177e4SLinus Torvalds 32811da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32821da177e4SLinus Torvalds { 32831da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32841da177e4SLinus Torvalds } 32851da177e4SLinus Torvalds 32861da177e4SLinus Torvalds /* get the link contents into pagecache */ 32871da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32881da177e4SLinus Torvalds { 3289ebd09abbSDuane Griffin char *kaddr; 32901da177e4SLinus Torvalds struct page *page; 32911da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3292090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32931da177e4SLinus Torvalds if (IS_ERR(page)) 32946fe6900eSNick Piggin return (char*)page; 32951da177e4SLinus Torvalds *ppage = page; 3296ebd09abbSDuane Griffin kaddr = kmap(page); 3297ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3298ebd09abbSDuane Griffin return kaddr; 32991da177e4SLinus Torvalds } 33001da177e4SLinus Torvalds 33011da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 33021da177e4SLinus Torvalds { 33031da177e4SLinus Torvalds struct page *page = NULL; 33041da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 33051da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 33061da177e4SLinus Torvalds if (page) { 33071da177e4SLinus Torvalds kunmap(page); 33081da177e4SLinus Torvalds page_cache_release(page); 33091da177e4SLinus Torvalds } 33101da177e4SLinus Torvalds return res; 33111da177e4SLinus Torvalds } 33121da177e4SLinus Torvalds 3313cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 33141da177e4SLinus Torvalds { 3315cc314eefSLinus Torvalds struct page *page = NULL; 33161da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3317cc314eefSLinus Torvalds return page; 33181da177e4SLinus Torvalds } 33191da177e4SLinus Torvalds 3320cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 33211da177e4SLinus Torvalds { 3322cc314eefSLinus Torvalds struct page *page = cookie; 3323cc314eefSLinus Torvalds 3324cc314eefSLinus Torvalds if (page) { 33251da177e4SLinus Torvalds kunmap(page); 33261da177e4SLinus Torvalds page_cache_release(page); 33271da177e4SLinus Torvalds } 33281da177e4SLinus Torvalds } 33291da177e4SLinus Torvalds 333054566b2cSNick Piggin /* 333154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 333254566b2cSNick Piggin */ 333354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33341da177e4SLinus Torvalds { 33351da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33360adb25d2SKirill Korotaev struct page *page; 3337afddba49SNick Piggin void *fsdata; 3338beb497abSDmitriy Monakhov int err; 33391da177e4SLinus Torvalds char *kaddr; 334054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 334154566b2cSNick Piggin if (nofs) 334254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33431da177e4SLinus Torvalds 33447e53cac4SNeilBrown retry: 3345afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 334654566b2cSNick Piggin flags, &page, &fsdata); 33471da177e4SLinus Torvalds if (err) 3348afddba49SNick Piggin goto fail; 3349afddba49SNick Piggin 33501da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33511da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33521da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3353afddba49SNick Piggin 3354afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3355afddba49SNick Piggin page, fsdata); 33561da177e4SLinus Torvalds if (err < 0) 33571da177e4SLinus Torvalds goto fail; 3358afddba49SNick Piggin if (err < len-1) 3359afddba49SNick Piggin goto retry; 3360afddba49SNick Piggin 33611da177e4SLinus Torvalds mark_inode_dirty(inode); 33621da177e4SLinus Torvalds return 0; 33631da177e4SLinus Torvalds fail: 33641da177e4SLinus Torvalds return err; 33651da177e4SLinus Torvalds } 33661da177e4SLinus Torvalds 33670adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33680adb25d2SKirill Korotaev { 33690adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 337054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33710adb25d2SKirill Korotaev } 33720adb25d2SKirill Korotaev 337392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33741da177e4SLinus Torvalds .readlink = generic_readlink, 33751da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33761da177e4SLinus Torvalds .put_link = page_put_link, 33771da177e4SLinus Torvalds }; 33781da177e4SLinus Torvalds 33792d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3380cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33811da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33821da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33831da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33841da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33851da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33861da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33871da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33881da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33891da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33900adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33911da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33921da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3393d1811465SAl Viro EXPORT_SYMBOL(kern_path); 339416f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3395f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33961da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33971da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33981da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33991da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 34001da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 34011da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 34021da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 34031da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 34041da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 34051da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 34061da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 34071da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 34081da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 34091da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3410