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> 351da177e4SLinus Torvalds #include <asm/uaccess.h> 361da177e4SLinus Torvalds 37e81e3f4dSEric Paris #include "internal.h" 38e81e3f4dSEric Paris 391da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 401da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 411da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 421da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 431da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 461da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 471da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 481da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 491da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 501da177e4SLinus Torvalds * the special cases of the former code. 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 531da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 541da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 571da177e4SLinus Torvalds * resolution to correspond with current state of the code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 601da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 611da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 621da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 631da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 641da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 651da177e4SLinus Torvalds */ 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 681da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 691da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 701da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 711da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 721da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7325985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1111da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1121da177e4SLinus Torvalds * kernel data space before using them.. 1131da177e4SLinus Torvalds * 1141da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1151da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1161da177e4SLinus Torvalds */ 117858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1181da177e4SLinus Torvalds { 1191da177e4SLinus Torvalds int retval; 1201da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1231da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1241da177e4SLinus Torvalds return -EFAULT; 1251da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1261da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1301da177e4SLinus Torvalds if (retval > 0) { 1311da177e4SLinus Torvalds if (retval < len) 1321da177e4SLinus Torvalds return 0; 1331da177e4SLinus Torvalds return -ENAMETOOLONG; 1341da177e4SLinus Torvalds } else if (!retval) 1351da177e4SLinus Torvalds retval = -ENOENT; 1361da177e4SLinus Torvalds return retval; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 139f52e0c11SAl Viro static char *getname_flags(const char __user * filename, int flags) 1401da177e4SLinus Torvalds { 1411da177e4SLinus Torvalds char *tmp, *result; 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1441da177e4SLinus Torvalds tmp = __getname(); 1451da177e4SLinus Torvalds if (tmp) { 1461da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds result = tmp; 1491da177e4SLinus Torvalds if (retval < 0) { 150f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 155f52e0c11SAl Viro } 1561da177e4SLinus Torvalds audit_getname(result); 1571da177e4SLinus Torvalds return result; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 160f52e0c11SAl Viro char *getname(const char __user * filename) 161f52e0c11SAl Viro { 162f52e0c11SAl Viro return getname_flags(filename, 0); 163f52e0c11SAl Viro } 164f52e0c11SAl Viro 1651da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1661da177e4SLinus Torvalds void putname(const char *name) 1671da177e4SLinus Torvalds { 1685ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1691da177e4SLinus Torvalds audit_putname(name); 1701da177e4SLinus Torvalds else 1711da177e4SLinus Torvalds __putname(name); 1721da177e4SLinus Torvalds } 1731da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1741da177e4SLinus Torvalds #endif 1751da177e4SLinus Torvalds 1765909ccaaSLinus Torvalds /* 1775909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1785909ccaaSLinus Torvalds */ 1797e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 1805909ccaaSLinus Torvalds { 1817e40145eSAl Viro int (*check_acl)(struct inode *inode, int mask); 18226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 1835909ccaaSLinus Torvalds 1849c2c7039SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK; 1855909ccaaSLinus Torvalds 186e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 187e795b717SSerge E. Hallyn goto other_perms; 188e795b717SSerge E. Hallyn 1895909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1905909ccaaSLinus Torvalds mode >>= 6; 1915909ccaaSLinus Torvalds else { 192178ea735SAl Viro check_acl = inode->i_op->check_acl; 1935909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1947e40145eSAl Viro int error = check_acl(inode, mask); 1955909ccaaSLinus Torvalds if (error != -EAGAIN) 1965909ccaaSLinus Torvalds return error; 1975909ccaaSLinus Torvalds } 1985909ccaaSLinus Torvalds 1995909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2005909ccaaSLinus Torvalds mode >>= 3; 2015909ccaaSLinus Torvalds } 2025909ccaaSLinus Torvalds 203e795b717SSerge E. Hallyn other_perms: 2045909ccaaSLinus Torvalds /* 2055909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2065909ccaaSLinus Torvalds */ 2079c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2085909ccaaSLinus Torvalds return 0; 2095909ccaaSLinus Torvalds return -EACCES; 2105909ccaaSLinus Torvalds } 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds /** 2131da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2141da177e4SLinus Torvalds * @inode: inode to check access rights for 2151da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 21639191628SRandy Dunlap * @flags: IPERM_FLAG_ flags. 2171da177e4SLinus Torvalds * 2181da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2191da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2201da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 221b74c79e9SNick Piggin * are used for other things. 222b74c79e9SNick Piggin * 223b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 224b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 225b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2261da177e4SLinus Torvalds */ 2272830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2281da177e4SLinus Torvalds { 2295909ccaaSLinus Torvalds int ret; 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds /* 2325909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2331da177e4SLinus Torvalds */ 2347e40145eSAl Viro ret = acl_permission_check(inode, mask); 2355909ccaaSLinus Torvalds if (ret != -EACCES) 2365909ccaaSLinus Torvalds return ret; 2371da177e4SLinus Torvalds 238d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 239d594e7ecSAl Viro /* DACs are overridable for directories */ 240d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 241d594e7ecSAl Viro return 0; 242d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 243d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 244d594e7ecSAl Viro return 0; 245d594e7ecSAl Viro return -EACCES; 246d594e7ecSAl Viro } 2471da177e4SLinus Torvalds /* 2481da177e4SLinus Torvalds * Read/write DACs are always overridable. 249d594e7ecSAl Viro * Executable DACs are overridable when there is 250d594e7ecSAl Viro * at least one exec bit set. 2511da177e4SLinus Torvalds */ 252d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 253e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 2541da177e4SLinus Torvalds return 0; 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds /* 2571da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2581da177e4SLinus Torvalds */ 2597ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 260d594e7ecSAl Viro if (mask == MAY_READ) 261e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 2621da177e4SLinus Torvalds return 0; 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds return -EACCES; 2651da177e4SLinus Torvalds } 2661da177e4SLinus Torvalds 267cb23beb5SChristoph Hellwig /** 268cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 269cb23beb5SChristoph Hellwig * @inode: inode to check permission on 270cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 271cb23beb5SChristoph Hellwig * 272cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 273cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 274cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 275cb23beb5SChristoph Hellwig * are used for other things. 276cb23beb5SChristoph Hellwig */ 277f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2781da177e4SLinus Torvalds { 279e6305c43SAl Viro int retval; 2801da177e4SLinus Torvalds 2811da177e4SLinus Torvalds if (mask & MAY_WRITE) { 28222590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2831da177e4SLinus Torvalds 2841da177e4SLinus Torvalds /* 2851da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2861da177e4SLinus Torvalds */ 2871da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2881da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2891da177e4SLinus Torvalds return -EROFS; 2901da177e4SLinus Torvalds 2911da177e4SLinus Torvalds /* 2921da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2931da177e4SLinus Torvalds */ 2941da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2951da177e4SLinus Torvalds return -EACCES; 2961da177e4SLinus Torvalds } 2971da177e4SLinus Torvalds 298acfa4380SAl Viro if (inode->i_op->permission) 29910556cb2SAl Viro retval = inode->i_op->permission(inode, mask); 300f696a365SMiklos Szeredi else 3012830ba7fSAl Viro retval = generic_permission(inode, mask); 302f696a365SMiklos Szeredi 3031da177e4SLinus Torvalds if (retval) 3041da177e4SLinus Torvalds return retval; 3051da177e4SLinus Torvalds 30608ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 30708ce5f16SSerge E. Hallyn if (retval) 30808ce5f16SSerge E. Hallyn return retval; 30908ce5f16SSerge E. Hallyn 310d09ca739SEric Paris return security_inode_permission(inode, mask); 3111da177e4SLinus Torvalds } 3121da177e4SLinus Torvalds 313f4d6ff89SAl Viro /** 314f4d6ff89SAl Viro * exec_permission - check for right to do lookups in a given directory 315f4d6ff89SAl Viro * @inode: inode to check permission on 316eecdd358SAl Viro * @mask: MAY_EXEC and possibly MAY_NOT_BLOCK flags. 317f4d6ff89SAl Viro * 318f4d6ff89SAl Viro * Short-cut version of inode_permission(), for calling on directories 319f4d6ff89SAl Viro * during pathname resolution. Combines parts of inode_permission() 320f4d6ff89SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 321f4d6ff89SAl Viro * 322f4d6ff89SAl Viro * If appropriate, check DAC only. If not appropriate, or 323f4d6ff89SAl Viro * short-cut DAC fails, then call ->permission() to do more 324f4d6ff89SAl Viro * complete permission check. 325f4d6ff89SAl Viro */ 326eecdd358SAl Viro static inline int exec_permission(struct inode *inode, int mask) 327f4d6ff89SAl Viro { 328f4d6ff89SAl Viro int ret; 329f4d6ff89SAl Viro struct user_namespace *ns = inode_userns(inode); 330f4d6ff89SAl Viro 331f4d6ff89SAl Viro if (inode->i_op->permission) { 33210556cb2SAl Viro ret = inode->i_op->permission(inode, mask); 333f4d6ff89SAl Viro if (likely(!ret)) 334f4d6ff89SAl Viro goto ok; 335f4d6ff89SAl Viro } else { 3367e40145eSAl Viro ret = acl_permission_check(inode, mask); 337f4d6ff89SAl Viro if (likely(!ret)) 338f4d6ff89SAl Viro goto ok; 339f4d6ff89SAl Viro if (ret != -EACCES) 340f4d6ff89SAl Viro return ret; 341f4d6ff89SAl Viro if (ns_capable(ns, CAP_DAC_OVERRIDE) || 342f4d6ff89SAl Viro ns_capable(ns, CAP_DAC_READ_SEARCH)) 343f4d6ff89SAl Viro goto ok; 344f4d6ff89SAl Viro } 345f4d6ff89SAl Viro return ret; 346f4d6ff89SAl Viro ok: 347eecdd358SAl Viro return security_inode_permission(inode, mask); 348f4d6ff89SAl Viro } 349f4d6ff89SAl Viro 3501d957f9bSJan Blunck /** 3515dd784d0SJan Blunck * path_get - get a reference to a path 3525dd784d0SJan Blunck * @path: path to get the reference to 3535dd784d0SJan Blunck * 3545dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3555dd784d0SJan Blunck */ 3565dd784d0SJan Blunck void path_get(struct path *path) 3575dd784d0SJan Blunck { 3585dd784d0SJan Blunck mntget(path->mnt); 3595dd784d0SJan Blunck dget(path->dentry); 3605dd784d0SJan Blunck } 3615dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3625dd784d0SJan Blunck 3635dd784d0SJan Blunck /** 3641d957f9bSJan Blunck * path_put - put a reference to a path 3651d957f9bSJan Blunck * @path: path to put the reference to 3661d957f9bSJan Blunck * 3671d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3681d957f9bSJan Blunck */ 3691d957f9bSJan Blunck void path_put(struct path *path) 3701da177e4SLinus Torvalds { 3711d957f9bSJan Blunck dput(path->dentry); 3721d957f9bSJan Blunck mntput(path->mnt); 3731da177e4SLinus Torvalds } 3741d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3751da177e4SLinus Torvalds 37619660af7SAl Viro /* 37731e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 37819660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 37919660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 38019660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 38119660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 38219660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 38319660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 38419660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 38531e6b01fSNick Piggin */ 38631e6b01fSNick Piggin 38731e6b01fSNick Piggin /** 38819660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 38919660af7SAl Viro * @nd: nameidata pathwalk data 39019660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 39139191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 39231e6b01fSNick Piggin * 39319660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 39419660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 39519660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 39631e6b01fSNick Piggin */ 39719660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 39831e6b01fSNick Piggin { 39931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 40031e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4015b6ca027SAl Viro int want_root = 0; 40231e6b01fSNick Piggin 40331e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4045b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4055b6ca027SAl Viro want_root = 1; 40631e6b01fSNick Piggin spin_lock(&fs->lock); 40731e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 40831e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 40931e6b01fSNick Piggin goto err_root; 41031e6b01fSNick Piggin } 41131e6b01fSNick Piggin spin_lock(&parent->d_lock); 41219660af7SAl Viro if (!dentry) { 41319660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 41419660af7SAl Viro goto err_parent; 41519660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 41619660af7SAl Viro } else { 41794c0d4ecSAl Viro if (dentry->d_parent != parent) 41894c0d4ecSAl Viro goto err_parent; 41931e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 42031e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 42119660af7SAl Viro goto err_child; 42231e6b01fSNick Piggin /* 42319660af7SAl Viro * If the sequence check on the child dentry passed, then 42419660af7SAl Viro * the child has not been removed from its parent. This 42519660af7SAl Viro * means the parent dentry must be valid and able to take 42619660af7SAl Viro * a reference at this point. 42731e6b01fSNick Piggin */ 42831e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 42931e6b01fSNick Piggin BUG_ON(!parent->d_count); 43031e6b01fSNick Piggin parent->d_count++; 43131e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 43219660af7SAl Viro } 43331e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4345b6ca027SAl Viro if (want_root) { 43531e6b01fSNick Piggin path_get(&nd->root); 43631e6b01fSNick Piggin spin_unlock(&fs->lock); 43731e6b01fSNick Piggin } 43831e6b01fSNick Piggin mntget(nd->path.mnt); 43931e6b01fSNick Piggin 44031e6b01fSNick Piggin rcu_read_unlock(); 44131e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 44231e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 44331e6b01fSNick Piggin return 0; 44419660af7SAl Viro 44519660af7SAl Viro err_child: 44631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 44719660af7SAl Viro err_parent: 44831e6b01fSNick Piggin spin_unlock(&parent->d_lock); 44931e6b01fSNick Piggin err_root: 4505b6ca027SAl Viro if (want_root) 45131e6b01fSNick Piggin spin_unlock(&fs->lock); 45231e6b01fSNick Piggin return -ECHILD; 45331e6b01fSNick Piggin } 45431e6b01fSNick Piggin 45531e6b01fSNick Piggin /** 456834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 457834f2a4aSTrond Myklebust * @nd: pointer to nameidata 458834f2a4aSTrond Myklebust */ 459834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 460834f2a4aSTrond Myklebust { 4612dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4622dab5974SLinus Torvalds 4632dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4642dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4652dab5974SLinus Torvalds put_filp(file); 466834f2a4aSTrond Myklebust else 4672dab5974SLinus Torvalds fput(file); 4682dab5974SLinus Torvalds } 469834f2a4aSTrond Myklebust } 470834f2a4aSTrond Myklebust 471f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 47234286d66SNick Piggin { 473f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 47434286d66SNick Piggin } 47534286d66SNick Piggin 476f5e1c1c1SAl Viro static struct dentry * 477bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 478bcdc5e01SIan Kent { 479f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 480bcdc5e01SIan Kent if (unlikely(status <= 0)) { 481bcdc5e01SIan Kent /* 482bcdc5e01SIan Kent * The dentry failed validation. 483bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 484bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 485bcdc5e01SIan Kent * to return a fail status. 486bcdc5e01SIan Kent */ 48734286d66SNick Piggin if (status < 0) { 48834286d66SNick Piggin dput(dentry); 48934286d66SNick Piggin dentry = ERR_PTR(status); 490f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 491bcdc5e01SIan Kent dput(dentry); 492bcdc5e01SIan Kent dentry = NULL; 493bcdc5e01SIan Kent } 494bcdc5e01SIan Kent } 495f5e1c1c1SAl Viro return dentry; 496f5e1c1c1SAl Viro } 497f5e1c1c1SAl Viro 4989f1fafeeSAl Viro /** 4999f1fafeeSAl Viro * complete_walk - successful completion of path walk 5009f1fafeeSAl Viro * @nd: pointer nameidata 50139159de2SJeff Layton * 5029f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5039f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5049f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5059f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5069f1fafeeSAl Viro * need to drop nd->path. 50739159de2SJeff Layton */ 5089f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 50939159de2SJeff Layton { 51016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 51139159de2SJeff Layton int status; 51239159de2SJeff Layton 5139f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5149f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5159f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5169f1fafeeSAl Viro nd->root.mnt = NULL; 5179f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5189f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5199f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5209f1fafeeSAl Viro rcu_read_unlock(); 5219f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5229f1fafeeSAl Viro return -ECHILD; 5239f1fafeeSAl Viro } 5249f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5259f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5269f1fafeeSAl Viro mntget(nd->path.mnt); 5279f1fafeeSAl Viro rcu_read_unlock(); 5289f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5299f1fafeeSAl Viro } 5309f1fafeeSAl Viro 53116c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 53239159de2SJeff Layton return 0; 53339159de2SJeff Layton 53416c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 53516c2cd71SAl Viro return 0; 53616c2cd71SAl Viro 53716c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 53816c2cd71SAl Viro return 0; 53916c2cd71SAl Viro 54016c2cd71SAl Viro /* Note: we do not d_invalidate() */ 54134286d66SNick Piggin status = d_revalidate(dentry, nd); 54239159de2SJeff Layton if (status > 0) 54339159de2SJeff Layton return 0; 54439159de2SJeff Layton 54516c2cd71SAl Viro if (!status) 54639159de2SJeff Layton status = -ESTALE; 54716c2cd71SAl Viro 5489f1fafeeSAl Viro path_put(&nd->path); 54939159de2SJeff Layton return status; 55039159de2SJeff Layton } 55139159de2SJeff Layton 5522a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5532a737871SAl Viro { 554f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 555f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5562a737871SAl Viro } 5572a737871SAl Viro 5586de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5596de88d72SAl Viro 56031e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 56131e6b01fSNick Piggin { 56231e6b01fSNick Piggin if (!nd->root.mnt) { 56331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 564c28cc364SNick Piggin unsigned seq; 565c28cc364SNick Piggin 566c28cc364SNick Piggin do { 567c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 56831e6b01fSNick Piggin nd->root = fs->root; 569c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 570c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 57131e6b01fSNick Piggin } 57231e6b01fSNick Piggin } 57331e6b01fSNick Piggin 574f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5751da177e4SLinus Torvalds { 57631e6b01fSNick Piggin int ret; 57731e6b01fSNick Piggin 5781da177e4SLinus Torvalds if (IS_ERR(link)) 5791da177e4SLinus Torvalds goto fail; 5801da177e4SLinus Torvalds 5811da177e4SLinus Torvalds if (*link == '/') { 5822a737871SAl Viro set_root(nd); 5831d957f9bSJan Blunck path_put(&nd->path); 5842a737871SAl Viro nd->path = nd->root; 5852a737871SAl Viro path_get(&nd->root); 58616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 5871da177e4SLinus Torvalds } 58831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 589b4091d5fSChristoph Hellwig 59031e6b01fSNick Piggin ret = link_path_walk(link, nd); 59131e6b01fSNick Piggin return ret; 5921da177e4SLinus Torvalds fail: 5931d957f9bSJan Blunck path_put(&nd->path); 5941da177e4SLinus Torvalds return PTR_ERR(link); 5951da177e4SLinus Torvalds } 5961da177e4SLinus Torvalds 5971d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 598051d3812SIan Kent { 599051d3812SIan Kent dput(path->dentry); 6004ac91378SJan Blunck if (path->mnt != nd->path.mnt) 601051d3812SIan Kent mntput(path->mnt); 602051d3812SIan Kent } 603051d3812SIan Kent 6047b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6057b9337aaSNick Piggin struct nameidata *nd) 606051d3812SIan Kent { 60731e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6084ac91378SJan Blunck dput(nd->path.dentry); 60931e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6104ac91378SJan Blunck mntput(nd->path.mnt); 6119a229683SHuang Shijie } 61231e6b01fSNick Piggin nd->path.mnt = path->mnt; 6134ac91378SJan Blunck nd->path.dentry = path->dentry; 614051d3812SIan Kent } 615051d3812SIan Kent 616574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 617574197e0SAl Viro { 618574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 619574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 620574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 621574197e0SAl Viro path_put(link); 622574197e0SAl Viro } 623574197e0SAl Viro 624def4af30SAl Viro static __always_inline int 625574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6261da177e4SLinus Torvalds { 6271da177e4SLinus Torvalds int error; 6287b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6291da177e4SLinus Torvalds 630844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 631844a3917SAl Viro 6320e794589SAl Viro if (link->mnt == nd->path.mnt) 6330e794589SAl Viro mntget(link->mnt); 6340e794589SAl Viro 635574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 636574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 637574197e0SAl Viro path_put(&nd->path); 638574197e0SAl Viro return -ELOOP; 639574197e0SAl Viro } 640574197e0SAl Viro cond_resched(); 641574197e0SAl Viro current->total_link_count++; 642574197e0SAl Viro 6437b9337aaSNick Piggin touch_atime(link->mnt, dentry); 6441da177e4SLinus Torvalds nd_set_link(nd, NULL); 645cd4e91d3SAl Viro 64636f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 64736f3b4f6SAl Viro if (error) { 64836f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 64936f3b4f6SAl Viro path_put(&nd->path); 65036f3b4f6SAl Viro return error; 65136f3b4f6SAl Viro } 65236f3b4f6SAl Viro 65386acdca1SAl Viro nd->last_type = LAST_BIND; 654def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 655def4af30SAl Viro error = PTR_ERR(*p); 656def4af30SAl Viro if (!IS_ERR(*p)) { 6571da177e4SLinus Torvalds char *s = nd_get_link(nd); 658cc314eefSLinus Torvalds error = 0; 6591da177e4SLinus Torvalds if (s) 6601da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 661bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 66216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 663b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 664b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 665bcda7652SAl Viro /* stepped on a _really_ weird one */ 666bcda7652SAl Viro path_put(&nd->path); 667bcda7652SAl Viro error = -ELOOP; 668bcda7652SAl Viro } 669bcda7652SAl Viro } 6701da177e4SLinus Torvalds } 6711da177e4SLinus Torvalds return error; 6721da177e4SLinus Torvalds } 6731da177e4SLinus Torvalds 67431e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 67531e6b01fSNick Piggin { 67631e6b01fSNick Piggin struct vfsmount *parent; 67731e6b01fSNick Piggin struct dentry *mountpoint; 67831e6b01fSNick Piggin 67931e6b01fSNick Piggin parent = path->mnt->mnt_parent; 68031e6b01fSNick Piggin if (parent == path->mnt) 68131e6b01fSNick Piggin return 0; 68231e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 68331e6b01fSNick Piggin path->dentry = mountpoint; 68431e6b01fSNick Piggin path->mnt = parent; 68531e6b01fSNick Piggin return 1; 68631e6b01fSNick Piggin } 68731e6b01fSNick Piggin 688bab77ebfSAl Viro int follow_up(struct path *path) 6891da177e4SLinus Torvalds { 6901da177e4SLinus Torvalds struct vfsmount *parent; 6911da177e4SLinus Torvalds struct dentry *mountpoint; 69299b7db7bSNick Piggin 69399b7db7bSNick Piggin br_read_lock(vfsmount_lock); 694bab77ebfSAl Viro parent = path->mnt->mnt_parent; 695bab77ebfSAl Viro if (parent == path->mnt) { 69699b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 6971da177e4SLinus Torvalds return 0; 6981da177e4SLinus Torvalds } 6991da177e4SLinus Torvalds mntget(parent); 700bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 70199b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 702bab77ebfSAl Viro dput(path->dentry); 703bab77ebfSAl Viro path->dentry = mountpoint; 704bab77ebfSAl Viro mntput(path->mnt); 705bab77ebfSAl Viro path->mnt = parent; 7061da177e4SLinus Torvalds return 1; 7071da177e4SLinus Torvalds } 7081da177e4SLinus Torvalds 709b5c84bf6SNick Piggin /* 7109875cf80SDavid Howells * Perform an automount 7119875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7129875cf80SDavid Howells * were called with. 7131da177e4SLinus Torvalds */ 7149875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7159875cf80SDavid Howells bool *need_mntput) 71631e6b01fSNick Piggin { 7179875cf80SDavid Howells struct vfsmount *mnt; 718ea5b778aSDavid Howells int err; 7199875cf80SDavid Howells 7209875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7219875cf80SDavid Howells return -EREMOTE; 7229875cf80SDavid Howells 7236f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 7246f45b656SDavid Howells * and this is the terminal part of the path. 7256f45b656SDavid Howells */ 7266f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 7276f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 7286f45b656SDavid Howells 7299875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 7309875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 7319875cf80SDavid Howells * or wants to open the mounted directory. 7329875cf80SDavid Howells * 7339875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 7349875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 7359875cf80SDavid Howells * appended a '/' to the name. 7369875cf80SDavid Howells */ 7379875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 7389875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 7399875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 7409875cf80SDavid Howells return -EISDIR; 7419875cf80SDavid Howells 7429875cf80SDavid Howells current->total_link_count++; 7439875cf80SDavid Howells if (current->total_link_count >= 40) 7449875cf80SDavid Howells return -ELOOP; 7459875cf80SDavid Howells 7469875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7479875cf80SDavid Howells if (IS_ERR(mnt)) { 7489875cf80SDavid Howells /* 7499875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7509875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7519875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7529875cf80SDavid Howells * 7539875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7549875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7559875cf80SDavid Howells * the path is inaccessible and we should say so. 7569875cf80SDavid Howells */ 7579875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 7589875cf80SDavid Howells return -EREMOTE; 7599875cf80SDavid Howells return PTR_ERR(mnt); 76031e6b01fSNick Piggin } 761ea5b778aSDavid Howells 7629875cf80SDavid Howells if (!mnt) /* mount collision */ 7639875cf80SDavid Howells return 0; 7649875cf80SDavid Howells 7658aef1884SAl Viro if (!*need_mntput) { 7668aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7678aef1884SAl Viro mntget(path->mnt); 7688aef1884SAl Viro *need_mntput = true; 7698aef1884SAl Viro } 77019a167afSAl Viro err = finish_automount(mnt, path); 771ea5b778aSDavid Howells 772ea5b778aSDavid Howells switch (err) { 773ea5b778aSDavid Howells case -EBUSY: 774ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 77519a167afSAl Viro return 0; 776ea5b778aSDavid Howells case 0: 7778aef1884SAl Viro path_put(path); 7789875cf80SDavid Howells path->mnt = mnt; 7799875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7809875cf80SDavid Howells return 0; 78119a167afSAl Viro default: 78219a167afSAl Viro return err; 7839875cf80SDavid Howells } 78419a167afSAl Viro 785ea5b778aSDavid Howells } 7869875cf80SDavid Howells 7879875cf80SDavid Howells /* 7889875cf80SDavid Howells * Handle a dentry that is managed in some way. 789cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7909875cf80SDavid Howells * - Flagged as mountpoint 7919875cf80SDavid Howells * - Flagged as automount point 7929875cf80SDavid Howells * 7939875cf80SDavid Howells * This may only be called in refwalk mode. 7949875cf80SDavid Howells * 7959875cf80SDavid Howells * Serialization is taken care of in namespace.c 7969875cf80SDavid Howells */ 7979875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7989875cf80SDavid Howells { 7998aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 8009875cf80SDavid Howells unsigned managed; 8019875cf80SDavid Howells bool need_mntput = false; 8028aef1884SAl Viro int ret = 0; 8039875cf80SDavid Howells 8049875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8059875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8069875cf80SDavid Howells * the components of that value change under us */ 8079875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8089875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8099875cf80SDavid Howells unlikely(managed != 0)) { 810cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 811cc53ce53SDavid Howells * being held. */ 812cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 813cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 814cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8151aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 816cc53ce53SDavid Howells if (ret < 0) 8178aef1884SAl Viro break; 818cc53ce53SDavid Howells } 819cc53ce53SDavid Howells 8209875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8219875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8229875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8239875cf80SDavid Howells if (mounted) { 8249875cf80SDavid Howells dput(path->dentry); 8259875cf80SDavid Howells if (need_mntput) 826463ffb2eSAl Viro mntput(path->mnt); 827463ffb2eSAl Viro path->mnt = mounted; 828463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8299875cf80SDavid Howells need_mntput = true; 8309875cf80SDavid Howells continue; 831463ffb2eSAl Viro } 832463ffb2eSAl Viro 8339875cf80SDavid Howells /* Something is mounted on this dentry in another 8349875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8359875cf80SDavid Howells * namespace got unmounted before we managed to get the 8369875cf80SDavid Howells * vfsmount_lock */ 8371da177e4SLinus Torvalds } 8389875cf80SDavid Howells 8399875cf80SDavid Howells /* Handle an automount point */ 8409875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8419875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8429875cf80SDavid Howells if (ret < 0) 8438aef1884SAl Viro break; 8449875cf80SDavid Howells continue; 8459875cf80SDavid Howells } 8469875cf80SDavid Howells 8479875cf80SDavid Howells /* We didn't change the current path point */ 8489875cf80SDavid Howells break; 8499875cf80SDavid Howells } 8508aef1884SAl Viro 8518aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8528aef1884SAl Viro mntput(path->mnt); 8538aef1884SAl Viro if (ret == -EISDIR) 8548aef1884SAl Viro ret = 0; 8558aef1884SAl Viro return ret; 8561da177e4SLinus Torvalds } 8571da177e4SLinus Torvalds 858cc53ce53SDavid Howells int follow_down_one(struct path *path) 8591da177e4SLinus Torvalds { 8601da177e4SLinus Torvalds struct vfsmount *mounted; 8611da177e4SLinus Torvalds 8621c755af4SAl Viro mounted = lookup_mnt(path); 8631da177e4SLinus Torvalds if (mounted) { 8649393bd07SAl Viro dput(path->dentry); 8659393bd07SAl Viro mntput(path->mnt); 8669393bd07SAl Viro path->mnt = mounted; 8679393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8681da177e4SLinus Torvalds return 1; 8691da177e4SLinus Torvalds } 8701da177e4SLinus Torvalds return 0; 8711da177e4SLinus Torvalds } 8721da177e4SLinus Torvalds 87362a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 87462a7375eSIan Kent { 87562a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 87662a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 87762a7375eSIan Kent } 87862a7375eSIan Kent 8799875cf80SDavid Howells /* 880287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 881287548e4SAl Viro * we meet a managed dentry that would need blocking. 8829875cf80SDavid Howells */ 8839875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 884287548e4SAl Viro struct inode **inode) 8859875cf80SDavid Howells { 88662a7375eSIan Kent for (;;) { 8879875cf80SDavid Howells struct vfsmount *mounted; 88862a7375eSIan Kent /* 88962a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 89062a7375eSIan Kent * that wants to block transit. 89162a7375eSIan Kent */ 892287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 893ab90911fSDavid Howells return false; 89462a7375eSIan Kent 89562a7375eSIan Kent if (!d_mountpoint(path->dentry)) 89662a7375eSIan Kent break; 89762a7375eSIan Kent 8989875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 8999875cf80SDavid Howells if (!mounted) 9009875cf80SDavid Howells break; 9019875cf80SDavid Howells path->mnt = mounted; 9029875cf80SDavid Howells path->dentry = mounted->mnt_root; 9039875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 90459430262SLinus Torvalds /* 90559430262SLinus Torvalds * Update the inode too. We don't need to re-check the 90659430262SLinus Torvalds * dentry sequence number here after this d_inode read, 90759430262SLinus Torvalds * because a mount-point is always pinned. 90859430262SLinus Torvalds */ 90959430262SLinus Torvalds *inode = path->dentry->d_inode; 9109875cf80SDavid Howells } 9119875cf80SDavid Howells return true; 9129875cf80SDavid Howells } 9139875cf80SDavid Howells 914dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 915287548e4SAl Viro { 916dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 917287548e4SAl Viro struct vfsmount *mounted; 918dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 919287548e4SAl Viro if (!mounted) 920287548e4SAl Viro break; 921dea39376SAl Viro nd->path.mnt = mounted; 922dea39376SAl Viro nd->path.dentry = mounted->mnt_root; 923dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 924287548e4SAl Viro } 925287548e4SAl Viro } 926287548e4SAl Viro 92731e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 92831e6b01fSNick Piggin { 92931e6b01fSNick Piggin set_root_rcu(nd); 93031e6b01fSNick Piggin 93131e6b01fSNick Piggin while (1) { 93231e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 93331e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 93431e6b01fSNick Piggin break; 93531e6b01fSNick Piggin } 93631e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 93731e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 93831e6b01fSNick Piggin struct dentry *parent = old->d_parent; 93931e6b01fSNick Piggin unsigned seq; 94031e6b01fSNick Piggin 94131e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 94231e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 943ef7562d5SAl Viro goto failed; 94431e6b01fSNick Piggin nd->path.dentry = parent; 94531e6b01fSNick Piggin nd->seq = seq; 94631e6b01fSNick Piggin break; 94731e6b01fSNick Piggin } 94831e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 94931e6b01fSNick Piggin break; 95031e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 95131e6b01fSNick Piggin } 952dea39376SAl Viro follow_mount_rcu(nd); 953dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 95431e6b01fSNick Piggin return 0; 955ef7562d5SAl Viro 956ef7562d5SAl Viro failed: 957ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9585b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 959ef7562d5SAl Viro nd->root.mnt = NULL; 960ef7562d5SAl Viro rcu_read_unlock(); 961ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 962ef7562d5SAl Viro return -ECHILD; 96331e6b01fSNick Piggin } 96431e6b01fSNick Piggin 9659875cf80SDavid Howells /* 966cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 967cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 968cc53ce53SDavid Howells * caller is permitted to proceed or not. 969cc53ce53SDavid Howells */ 9707cc90cc3SAl Viro int follow_down(struct path *path) 971cc53ce53SDavid Howells { 972cc53ce53SDavid Howells unsigned managed; 973cc53ce53SDavid Howells int ret; 974cc53ce53SDavid Howells 975cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 976cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 977cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 978cc53ce53SDavid Howells * being held. 979cc53ce53SDavid Howells * 980cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 981cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 982cc53ce53SDavid Howells * other than its daemon the right to mount on its 983cc53ce53SDavid Howells * superstructure. 984cc53ce53SDavid Howells * 985cc53ce53SDavid Howells * The filesystem may sleep at this point. 986cc53ce53SDavid Howells */ 987cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 988cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 989cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 990ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 9911aed3e42SAl Viro path->dentry, false); 992cc53ce53SDavid Howells if (ret < 0) 993cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 994cc53ce53SDavid Howells } 995cc53ce53SDavid Howells 996cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 997cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 998cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 999cc53ce53SDavid Howells if (!mounted) 1000cc53ce53SDavid Howells break; 1001cc53ce53SDavid Howells dput(path->dentry); 1002cc53ce53SDavid Howells mntput(path->mnt); 1003cc53ce53SDavid Howells path->mnt = mounted; 1004cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1005cc53ce53SDavid Howells continue; 1006cc53ce53SDavid Howells } 1007cc53ce53SDavid Howells 1008cc53ce53SDavid Howells /* Don't handle automount points here */ 1009cc53ce53SDavid Howells break; 1010cc53ce53SDavid Howells } 1011cc53ce53SDavid Howells return 0; 1012cc53ce53SDavid Howells } 1013cc53ce53SDavid Howells 1014cc53ce53SDavid Howells /* 10159875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10169875cf80SDavid Howells */ 10179875cf80SDavid Howells static void follow_mount(struct path *path) 10189875cf80SDavid Howells { 10199875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10209875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10219875cf80SDavid Howells if (!mounted) 10229875cf80SDavid Howells break; 10239875cf80SDavid Howells dput(path->dentry); 10249875cf80SDavid Howells mntput(path->mnt); 10259875cf80SDavid Howells path->mnt = mounted; 10269875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10279875cf80SDavid Howells } 10289875cf80SDavid Howells } 10299875cf80SDavid Howells 103031e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10311da177e4SLinus Torvalds { 10322a737871SAl Viro set_root(nd); 1033e518ddb7SAndreas Mohr 10341da177e4SLinus Torvalds while(1) { 10354ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10361da177e4SLinus Torvalds 10372a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10382a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10391da177e4SLinus Torvalds break; 10401da177e4SLinus Torvalds } 10414ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10423088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10433088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10441da177e4SLinus Torvalds dput(old); 10451da177e4SLinus Torvalds break; 10461da177e4SLinus Torvalds } 10473088dd70SAl Viro if (!follow_up(&nd->path)) 10481da177e4SLinus Torvalds break; 10491da177e4SLinus Torvalds } 105079ed0226SAl Viro follow_mount(&nd->path); 105131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10521da177e4SLinus Torvalds } 10531da177e4SLinus Torvalds 10541da177e4SLinus Torvalds /* 1055baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1056baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1057baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1058baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1059baa03890SNick Piggin */ 1060baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1061baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1062baa03890SNick Piggin { 1063baa03890SNick Piggin struct inode *inode = parent->d_inode; 1064baa03890SNick Piggin struct dentry *dentry; 1065baa03890SNick Piggin struct dentry *old; 1066baa03890SNick Piggin 1067baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1068baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1069baa03890SNick Piggin return ERR_PTR(-ENOENT); 1070baa03890SNick Piggin 1071baa03890SNick Piggin dentry = d_alloc(parent, name); 1072baa03890SNick Piggin if (unlikely(!dentry)) 1073baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1074baa03890SNick Piggin 1075baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1076baa03890SNick Piggin if (unlikely(old)) { 1077baa03890SNick Piggin dput(dentry); 1078baa03890SNick Piggin dentry = old; 1079baa03890SNick Piggin } 1080baa03890SNick Piggin return dentry; 1081baa03890SNick Piggin } 1082baa03890SNick Piggin 1083baa03890SNick Piggin /* 108444396f4bSJosef Bacik * We already have a dentry, but require a lookup to be performed on the parent 108544396f4bSJosef Bacik * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. 108644396f4bSJosef Bacik * parent->d_inode->i_mutex must be held. d_lookup must have verified that no 108744396f4bSJosef Bacik * child exists while under i_mutex. 108844396f4bSJosef Bacik */ 108944396f4bSJosef Bacik static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, 109044396f4bSJosef Bacik struct nameidata *nd) 109144396f4bSJosef Bacik { 109244396f4bSJosef Bacik struct inode *inode = parent->d_inode; 109344396f4bSJosef Bacik struct dentry *old; 109444396f4bSJosef Bacik 109544396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 109644396f4bSJosef Bacik if (unlikely(IS_DEADDIR(inode))) 109744396f4bSJosef Bacik return ERR_PTR(-ENOENT); 109844396f4bSJosef Bacik 109944396f4bSJosef Bacik old = inode->i_op->lookup(inode, dentry, nd); 110044396f4bSJosef Bacik if (unlikely(old)) { 110144396f4bSJosef Bacik dput(dentry); 110244396f4bSJosef Bacik dentry = old; 110344396f4bSJosef Bacik } 110444396f4bSJosef Bacik return dentry; 110544396f4bSJosef Bacik } 110644396f4bSJosef Bacik 110744396f4bSJosef Bacik /* 11081da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11091da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11101da177e4SLinus Torvalds * It _is_ time-critical. 11111da177e4SLinus Torvalds */ 11121da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 111331e6b01fSNick Piggin struct path *path, struct inode **inode) 11141da177e4SLinus Torvalds { 11154ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 111631e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11175a18fff2SAl Viro int need_reval = 1; 11185a18fff2SAl Viro int status = 1; 11199875cf80SDavid Howells int err; 11209875cf80SDavid Howells 11213cac260aSAl Viro /* 1122b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1123b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1124b04f784eSNick Piggin * do the non-racy lookup, below. 1125b04f784eSNick Piggin */ 112631e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 112731e6b01fSNick Piggin unsigned seq; 112831e6b01fSNick Piggin *inode = nd->inode; 112931e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11305a18fff2SAl Viro if (!dentry) 11315a18fff2SAl Viro goto unlazy; 11325a18fff2SAl Viro 113331e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 113431e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 113531e6b01fSNick Piggin return -ECHILD; 113631e6b01fSNick Piggin nd->seq = seq; 11375a18fff2SAl Viro 113824643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11395a18fff2SAl Viro status = d_revalidate(dentry, nd); 11405a18fff2SAl Viro if (unlikely(status <= 0)) { 11415a18fff2SAl Viro if (status != -ECHILD) 11425a18fff2SAl Viro need_reval = 0; 11435a18fff2SAl Viro goto unlazy; 11445a18fff2SAl Viro } 114524643087SAl Viro } 114644396f4bSJosef Bacik if (unlikely(d_need_lookup(dentry))) 114744396f4bSJosef Bacik goto unlazy; 114831e6b01fSNick Piggin path->mnt = mnt; 114931e6b01fSNick Piggin path->dentry = dentry; 1150d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1151d6e9bd25SAl Viro goto unlazy; 1152d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1153d6e9bd25SAl Viro goto unlazy; 11549875cf80SDavid Howells return 0; 11555a18fff2SAl Viro unlazy: 115619660af7SAl Viro if (unlazy_walk(nd, dentry)) 11575a18fff2SAl Viro return -ECHILD; 11585a18fff2SAl Viro } else { 115931e6b01fSNick Piggin dentry = __d_lookup(parent, name); 116024643087SAl Viro } 11615a18fff2SAl Viro 116244396f4bSJosef Bacik if (dentry && unlikely(d_need_lookup(dentry))) { 116344396f4bSJosef Bacik dput(dentry); 116444396f4bSJosef Bacik dentry = NULL; 116544396f4bSJosef Bacik } 11665a18fff2SAl Viro retry: 11675a18fff2SAl Viro if (unlikely(!dentry)) { 11685a18fff2SAl Viro struct inode *dir = parent->d_inode; 11695a18fff2SAl Viro BUG_ON(nd->inode != dir); 11705a18fff2SAl Viro 11715a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11725a18fff2SAl Viro dentry = d_lookup(parent, name); 11735a18fff2SAl Viro if (likely(!dentry)) { 11745a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 11755a18fff2SAl Viro if (IS_ERR(dentry)) { 11765a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11775a18fff2SAl Viro return PTR_ERR(dentry); 11785a18fff2SAl Viro } 11795a18fff2SAl Viro /* known good */ 11805a18fff2SAl Viro need_reval = 0; 11815a18fff2SAl Viro status = 1; 118244396f4bSJosef Bacik } else if (unlikely(d_need_lookup(dentry))) { 118344396f4bSJosef Bacik dentry = d_inode_lookup(parent, dentry, nd); 118444396f4bSJosef Bacik if (IS_ERR(dentry)) { 118544396f4bSJosef Bacik mutex_unlock(&dir->i_mutex); 118644396f4bSJosef Bacik return PTR_ERR(dentry); 118744396f4bSJosef Bacik } 118844396f4bSJosef Bacik /* known good */ 118944396f4bSJosef Bacik need_reval = 0; 119044396f4bSJosef Bacik status = 1; 11915a18fff2SAl Viro } 11925a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11935a18fff2SAl Viro } 11945a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 11955a18fff2SAl Viro status = d_revalidate(dentry, nd); 11965a18fff2SAl Viro if (unlikely(status <= 0)) { 11975a18fff2SAl Viro if (status < 0) { 11985a18fff2SAl Viro dput(dentry); 11995a18fff2SAl Viro return status; 12005a18fff2SAl Viro } 12015a18fff2SAl Viro if (!d_invalidate(dentry)) { 12025a18fff2SAl Viro dput(dentry); 12035a18fff2SAl Viro dentry = NULL; 12045a18fff2SAl Viro need_reval = 1; 12055a18fff2SAl Viro goto retry; 12065a18fff2SAl Viro } 12075a18fff2SAl Viro } 12085a18fff2SAl Viro 12091da177e4SLinus Torvalds path->mnt = mnt; 12101da177e4SLinus Torvalds path->dentry = dentry; 12119875cf80SDavid Howells err = follow_managed(path, nd->flags); 121289312214SIan Kent if (unlikely(err < 0)) { 121389312214SIan Kent path_put_conditional(path, nd); 12149875cf80SDavid Howells return err; 121589312214SIan Kent } 121631e6b01fSNick Piggin *inode = path->dentry->d_inode; 12171da177e4SLinus Torvalds return 0; 12181da177e4SLinus Torvalds } 12191da177e4SLinus Torvalds 122052094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 122152094c8aSAl Viro { 122252094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 1223eecdd358SAl Viro int err = exec_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 122452094c8aSAl Viro if (err != -ECHILD) 122552094c8aSAl Viro return err; 122619660af7SAl Viro if (unlazy_walk(nd, NULL)) 122752094c8aSAl Viro return -ECHILD; 122852094c8aSAl Viro } 1229eecdd358SAl Viro return exec_permission(nd->inode, MAY_EXEC); 123052094c8aSAl Viro } 123152094c8aSAl Viro 12329856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12339856fa1bSAl Viro { 12349856fa1bSAl Viro if (type == LAST_DOTDOT) { 12359856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12369856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12379856fa1bSAl Viro return -ECHILD; 12389856fa1bSAl Viro } else 12399856fa1bSAl Viro follow_dotdot(nd); 12409856fa1bSAl Viro } 12419856fa1bSAl Viro return 0; 12429856fa1bSAl Viro } 12439856fa1bSAl Viro 1244951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1245951361f9SAl Viro { 1246951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1247951361f9SAl Viro path_put(&nd->path); 1248951361f9SAl Viro } else { 1249951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12505b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1251951361f9SAl Viro nd->root.mnt = NULL; 1252951361f9SAl Viro rcu_read_unlock(); 1253951361f9SAl Viro br_read_unlock(vfsmount_lock); 1254951361f9SAl Viro } 1255951361f9SAl Viro } 1256951361f9SAl Viro 1257ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1258ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1259ce57dfc1SAl Viro { 1260ce57dfc1SAl Viro struct inode *inode; 1261ce57dfc1SAl Viro int err; 1262ce57dfc1SAl Viro /* 1263ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1264ce57dfc1SAl Viro * to be able to know about the current root directory and 1265ce57dfc1SAl Viro * parent relationships. 1266ce57dfc1SAl Viro */ 1267ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1268ce57dfc1SAl Viro return handle_dots(nd, type); 1269ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1270ce57dfc1SAl Viro if (unlikely(err)) { 1271ce57dfc1SAl Viro terminate_walk(nd); 1272ce57dfc1SAl Viro return err; 1273ce57dfc1SAl Viro } 1274ce57dfc1SAl Viro if (!inode) { 1275ce57dfc1SAl Viro path_to_nameidata(path, nd); 1276ce57dfc1SAl Viro terminate_walk(nd); 1277ce57dfc1SAl Viro return -ENOENT; 1278ce57dfc1SAl Viro } 1279ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 128019660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 128119660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 128219660af7SAl Viro terminate_walk(nd); 1283ce57dfc1SAl Viro return -ECHILD; 128419660af7SAl Viro } 128519660af7SAl Viro } 1286ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1287ce57dfc1SAl Viro return 1; 1288ce57dfc1SAl Viro } 1289ce57dfc1SAl Viro path_to_nameidata(path, nd); 1290ce57dfc1SAl Viro nd->inode = inode; 1291ce57dfc1SAl Viro return 0; 1292ce57dfc1SAl Viro } 1293ce57dfc1SAl Viro 12941da177e4SLinus Torvalds /* 1295b356379aSAl Viro * This limits recursive symlink follows to 8, while 1296b356379aSAl Viro * limiting consecutive symlinks to 40. 1297b356379aSAl Viro * 1298b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1299b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1300b356379aSAl Viro */ 1301b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1302b356379aSAl Viro { 1303b356379aSAl Viro int res; 1304b356379aSAl Viro 1305b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1306b356379aSAl Viro path_put_conditional(path, nd); 1307b356379aSAl Viro path_put(&nd->path); 1308b356379aSAl Viro return -ELOOP; 1309b356379aSAl Viro } 13101a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1311b356379aSAl Viro 1312b356379aSAl Viro nd->depth++; 1313b356379aSAl Viro current->link_count++; 1314b356379aSAl Viro 1315b356379aSAl Viro do { 1316b356379aSAl Viro struct path link = *path; 1317b356379aSAl Viro void *cookie; 1318574197e0SAl Viro 1319574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1320b356379aSAl Viro if (!res) 1321b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1322b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1323574197e0SAl Viro put_link(nd, &link, cookie); 1324b356379aSAl Viro } while (res > 0); 1325b356379aSAl Viro 1326b356379aSAl Viro current->link_count--; 1327b356379aSAl Viro nd->depth--; 1328b356379aSAl Viro return res; 1329b356379aSAl Viro } 1330b356379aSAl Viro 1331b356379aSAl Viro /* 13321da177e4SLinus Torvalds * Name resolution. 1333ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1334ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13351da177e4SLinus Torvalds * 1336ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1337ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13381da177e4SLinus Torvalds */ 13396de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13401da177e4SLinus Torvalds { 13411da177e4SLinus Torvalds struct path next; 13421da177e4SLinus Torvalds int err; 13431da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13441da177e4SLinus Torvalds 13451da177e4SLinus Torvalds while (*name=='/') 13461da177e4SLinus Torvalds name++; 13471da177e4SLinus Torvalds if (!*name) 1348086e183aSAl Viro return 0; 13491da177e4SLinus Torvalds 13501da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13511da177e4SLinus Torvalds for(;;) { 13521da177e4SLinus Torvalds unsigned long hash; 13531da177e4SLinus Torvalds struct qstr this; 13541da177e4SLinus Torvalds unsigned int c; 1355fe479a58SAl Viro int type; 13561da177e4SLinus Torvalds 1357cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 135852094c8aSAl Viro 135952094c8aSAl Viro err = may_lookup(nd); 13601da177e4SLinus Torvalds if (err) 13611da177e4SLinus Torvalds break; 13621da177e4SLinus Torvalds 13631da177e4SLinus Torvalds this.name = name; 13641da177e4SLinus Torvalds c = *(const unsigned char *)name; 13651da177e4SLinus Torvalds 13661da177e4SLinus Torvalds hash = init_name_hash(); 13671da177e4SLinus Torvalds do { 13681da177e4SLinus Torvalds name++; 13691da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13701da177e4SLinus Torvalds c = *(const unsigned char *)name; 13711da177e4SLinus Torvalds } while (c && (c != '/')); 13721da177e4SLinus Torvalds this.len = name - (const char *) this.name; 13731da177e4SLinus Torvalds this.hash = end_name_hash(hash); 13741da177e4SLinus Torvalds 1375fe479a58SAl Viro type = LAST_NORM; 1376fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1377fe479a58SAl Viro case 2: 137816c2cd71SAl Viro if (this.name[1] == '.') { 1379fe479a58SAl Viro type = LAST_DOTDOT; 138016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 138116c2cd71SAl Viro } 1382fe479a58SAl Viro break; 1383fe479a58SAl Viro case 1: 1384fe479a58SAl Viro type = LAST_DOT; 1385fe479a58SAl Viro } 13865a202bcdSAl Viro if (likely(type == LAST_NORM)) { 13875a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 138816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 13895a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 13905a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 13915a202bcdSAl Viro &this); 13925a202bcdSAl Viro if (err < 0) 13935a202bcdSAl Viro break; 13945a202bcdSAl Viro } 13955a202bcdSAl Viro } 1396fe479a58SAl Viro 13971da177e4SLinus Torvalds /* remove trailing slashes? */ 13981da177e4SLinus Torvalds if (!c) 13991da177e4SLinus Torvalds goto last_component; 14001da177e4SLinus Torvalds while (*++name == '/'); 14011da177e4SLinus Torvalds if (!*name) 1402b356379aSAl Viro goto last_component; 14031da177e4SLinus Torvalds 1404ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1405ce57dfc1SAl Viro if (err < 0) 1406ce57dfc1SAl Viro return err; 1407fe479a58SAl Viro 1408ce57dfc1SAl Viro if (err) { 1409b356379aSAl Viro err = nested_symlink(&next, nd); 14101da177e4SLinus Torvalds if (err) 1411a7472babSAl Viro return err; 141231e6b01fSNick Piggin } 14131da177e4SLinus Torvalds err = -ENOTDIR; 141431e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14151da177e4SLinus Torvalds break; 14161da177e4SLinus Torvalds continue; 14171da177e4SLinus Torvalds /* here ends the main loop */ 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds last_component: 1420f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1421f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1422ce57dfc1SAl Viro nd->last = this; 1423ce57dfc1SAl Viro nd->last_type = type; 1424ce57dfc1SAl Viro return 0; 1425ce57dfc1SAl Viro } 1426951361f9SAl Viro terminate_walk(nd); 14271da177e4SLinus Torvalds return err; 14281da177e4SLinus Torvalds } 14291da177e4SLinus Torvalds 143070e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 143170e9b357SAl Viro struct nameidata *nd, struct file **fp) 143231e6b01fSNick Piggin { 143331e6b01fSNick Piggin int retval = 0; 143431e6b01fSNick Piggin int fput_needed; 143531e6b01fSNick Piggin struct file *file; 143631e6b01fSNick Piggin 143731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 143816c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 143931e6b01fSNick Piggin nd->depth = 0; 14405b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14415b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 144273d049a4SAl Viro if (*name) { 14435b6ca027SAl Viro if (!inode->i_op->lookup) 14445b6ca027SAl Viro return -ENOTDIR; 14455b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14465b6ca027SAl Viro if (retval) 14475b6ca027SAl Viro return retval; 144873d049a4SAl Viro } 14495b6ca027SAl Viro nd->path = nd->root; 14505b6ca027SAl Viro nd->inode = inode; 14515b6ca027SAl Viro if (flags & LOOKUP_RCU) { 14525b6ca027SAl Viro br_read_lock(vfsmount_lock); 14535b6ca027SAl Viro rcu_read_lock(); 14545b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 14555b6ca027SAl Viro } else { 14565b6ca027SAl Viro path_get(&nd->path); 14575b6ca027SAl Viro } 14585b6ca027SAl Viro return 0; 14595b6ca027SAl Viro } 14605b6ca027SAl Viro 146131e6b01fSNick Piggin nd->root.mnt = NULL; 146231e6b01fSNick Piggin 146331e6b01fSNick Piggin if (*name=='/') { 1464e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 146531e6b01fSNick Piggin br_read_lock(vfsmount_lock); 146631e6b01fSNick Piggin rcu_read_lock(); 1467e41f7d4eSAl Viro set_root_rcu(nd); 1468e41f7d4eSAl Viro } else { 1469e41f7d4eSAl Viro set_root(nd); 1470e41f7d4eSAl Viro path_get(&nd->root); 1471e41f7d4eSAl Viro } 147231e6b01fSNick Piggin nd->path = nd->root; 147331e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1474e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 147531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1476c28cc364SNick Piggin unsigned seq; 147731e6b01fSNick Piggin 147831e6b01fSNick Piggin br_read_lock(vfsmount_lock); 147931e6b01fSNick Piggin rcu_read_lock(); 148031e6b01fSNick Piggin 1481c28cc364SNick Piggin do { 1482c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 148331e6b01fSNick Piggin nd->path = fs->pwd; 1484c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1485c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1486e41f7d4eSAl Viro } else { 1487e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1488e41f7d4eSAl Viro } 148931e6b01fSNick Piggin } else { 149031e6b01fSNick Piggin struct dentry *dentry; 149131e6b01fSNick Piggin 14921abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 149331e6b01fSNick Piggin retval = -EBADF; 149431e6b01fSNick Piggin if (!file) 149531e6b01fSNick Piggin goto out_fail; 149631e6b01fSNick Piggin 149731e6b01fSNick Piggin dentry = file->f_path.dentry; 149831e6b01fSNick Piggin 1499f52e0c11SAl Viro if (*name) { 150031e6b01fSNick Piggin retval = -ENOTDIR; 150131e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 150231e6b01fSNick Piggin goto fput_fail; 150331e6b01fSNick Piggin 1504eecdd358SAl Viro retval = exec_permission(dentry->d_inode, MAY_EXEC); 150531e6b01fSNick Piggin if (retval) 150631e6b01fSNick Piggin goto fput_fail; 1507f52e0c11SAl Viro } 150831e6b01fSNick Piggin 150931e6b01fSNick Piggin nd->path = file->f_path; 1510e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 151131e6b01fSNick Piggin if (fput_needed) 151270e9b357SAl Viro *fp = file; 1513c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 151431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 151531e6b01fSNick Piggin rcu_read_lock(); 15165590ff0dSUlrich Drepper } else { 15175dd784d0SJan Blunck path_get(&file->f_path); 15185590ff0dSUlrich Drepper fput_light(file, fput_needed); 15191da177e4SLinus Torvalds } 1520e41f7d4eSAl Viro } 1521e41f7d4eSAl Viro 152231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15239b4a9b14SAl Viro return 0; 15242dfdd266SJosef 'Jeff' Sipek 15259b4a9b14SAl Viro fput_fail: 15269b4a9b14SAl Viro fput_light(file, fput_needed); 15279b4a9b14SAl Viro out_fail: 15289b4a9b14SAl Viro return retval; 15299b4a9b14SAl Viro } 15309b4a9b14SAl Viro 1531bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1532bd92d7feSAl Viro { 1533bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1534bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1535bd92d7feSAl Viro 1536bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1537bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1538bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1539bd92d7feSAl Viro } 1540bd92d7feSAl Viro 15419b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1542ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15439b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15449b4a9b14SAl Viro { 154570e9b357SAl Viro struct file *base = NULL; 1546bd92d7feSAl Viro struct path path; 1547bd92d7feSAl Viro int err; 154831e6b01fSNick Piggin 154931e6b01fSNick Piggin /* 155031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 155131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 155231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 155331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 155431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 155531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 155631e6b01fSNick Piggin * analogue, foo_rcu(). 155731e6b01fSNick Piggin * 155831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 155931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 156031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 156131e6b01fSNick Piggin * be able to complete). 156231e6b01fSNick Piggin */ 1563bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1564ee0827cdSAl Viro 1565bd92d7feSAl Viro if (unlikely(err)) 1566bd92d7feSAl Viro return err; 1567ee0827cdSAl Viro 1568ee0827cdSAl Viro current->total_link_count = 0; 1569bd92d7feSAl Viro err = link_path_walk(name, nd); 1570bd92d7feSAl Viro 1571bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1572bd92d7feSAl Viro err = lookup_last(nd, &path); 1573bd92d7feSAl Viro while (err > 0) { 1574bd92d7feSAl Viro void *cookie; 1575bd92d7feSAl Viro struct path link = path; 1576bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1577574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1578bd92d7feSAl Viro if (!err) 1579bd92d7feSAl Viro err = lookup_last(nd, &path); 1580574197e0SAl Viro put_link(nd, &link, cookie); 1581bd92d7feSAl Viro } 1582bd92d7feSAl Viro } 1583ee0827cdSAl Viro 15849f1fafeeSAl Viro if (!err) 15859f1fafeeSAl Viro err = complete_walk(nd); 1586bd92d7feSAl Viro 1587bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1588bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1589bd92d7feSAl Viro path_put(&nd->path); 1590bd23a539SAl Viro err = -ENOTDIR; 1591bd92d7feSAl Viro } 1592bd92d7feSAl Viro } 159316c2cd71SAl Viro 159470e9b357SAl Viro if (base) 159570e9b357SAl Viro fput(base); 1596ee0827cdSAl Viro 15975b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 159831e6b01fSNick Piggin path_put(&nd->root); 159931e6b01fSNick Piggin nd->root.mnt = NULL; 160031e6b01fSNick Piggin } 1601bd92d7feSAl Viro return err; 160231e6b01fSNick Piggin } 160331e6b01fSNick Piggin 1604ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1605ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1606ee0827cdSAl Viro { 1607ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1608ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1609ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1610ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1611ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1612ee0827cdSAl Viro 161331e6b01fSNick Piggin if (likely(!retval)) { 161431e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 161531e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 161631e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 161731e6b01fSNick Piggin } 161831e6b01fSNick Piggin } 1619170aa3d0SUlrich Drepper return retval; 16201da177e4SLinus Torvalds } 16211da177e4SLinus Torvalds 1622c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16235590ff0dSUlrich Drepper { 1624c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16255590ff0dSUlrich Drepper } 16265590ff0dSUlrich Drepper 1627d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1628d1811465SAl Viro { 1629d1811465SAl Viro struct nameidata nd; 1630d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1631d1811465SAl Viro if (!res) 1632d1811465SAl Viro *path = nd.path; 1633d1811465SAl Viro return res; 1634d1811465SAl Viro } 1635d1811465SAl Viro 163616f18200SJosef 'Jeff' Sipek /** 163716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 163816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 163916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 164016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 164116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 164216f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 164316f18200SJosef 'Jeff' Sipek */ 164416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 164516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 164616f18200SJosef 'Jeff' Sipek struct nameidata *nd) 164716f18200SJosef 'Jeff' Sipek { 16485b6ca027SAl Viro nd->root.dentry = dentry; 16495b6ca027SAl Viro nd->root.mnt = mnt; 16505b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 16515b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 165216f18200SJosef 'Jeff' Sipek } 165316f18200SJosef 'Jeff' Sipek 1654eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1655eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16561da177e4SLinus Torvalds { 165781fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16581da177e4SLinus Torvalds struct dentry *dentry; 16591da177e4SLinus Torvalds int err; 16601da177e4SLinus Torvalds 1661eecdd358SAl Viro err = exec_permission(inode, MAY_EXEC); 166281fca444SChristoph Hellwig if (err) 166381fca444SChristoph Hellwig return ERR_PTR(err); 16641da177e4SLinus Torvalds 16651da177e4SLinus Torvalds /* 1666b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1667b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1668b04f784eSNick Piggin * a double lookup. 16696e6b1bd1SAl Viro */ 16706e6b1bd1SAl Viro dentry = d_lookup(base, name); 16716e6b1bd1SAl Viro 167244396f4bSJosef Bacik if (dentry && d_need_lookup(dentry)) { 167344396f4bSJosef Bacik /* 167444396f4bSJosef Bacik * __lookup_hash is called with the parent dir's i_mutex already 167544396f4bSJosef Bacik * held, so we are good to go here. 167644396f4bSJosef Bacik */ 167744396f4bSJosef Bacik dentry = d_inode_lookup(base, dentry, nd); 167844396f4bSJosef Bacik if (IS_ERR(dentry)) 167944396f4bSJosef Bacik return dentry; 168044396f4bSJosef Bacik } 168144396f4bSJosef Bacik 1682fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 16836e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 16846e6b1bd1SAl Viro 16851da177e4SLinus Torvalds if (!dentry) 1686baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 16875a202bcdSAl Viro 16881da177e4SLinus Torvalds return dentry; 16891da177e4SLinus Torvalds } 16901da177e4SLinus Torvalds 1691057f6c01SJames Morris /* 1692057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1693057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1694057f6c01SJames Morris * SMP-safe. 1695057f6c01SJames Morris */ 1696a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 16971da177e4SLinus Torvalds { 16984ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 16991da177e4SLinus Torvalds } 17001da177e4SLinus Torvalds 1701eead1911SChristoph Hellwig /** 1702a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1703eead1911SChristoph Hellwig * @name: pathname component to lookup 1704eead1911SChristoph Hellwig * @base: base directory to lookup from 1705eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1706eead1911SChristoph Hellwig * 1707a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1708a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1709eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1710eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1711eead1911SChristoph Hellwig */ 1712057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1713057f6c01SJames Morris { 1714057f6c01SJames Morris struct qstr this; 17156a96ba54SAl Viro unsigned long hash; 17166a96ba54SAl Viro unsigned int c; 1717057f6c01SJames Morris 17182f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17192f9092e1SDavid Woodhouse 17206a96ba54SAl Viro this.name = name; 17216a96ba54SAl Viro this.len = len; 17226a96ba54SAl Viro if (!len) 17236a96ba54SAl Viro return ERR_PTR(-EACCES); 17246a96ba54SAl Viro 17256a96ba54SAl Viro hash = init_name_hash(); 17266a96ba54SAl Viro while (len--) { 17276a96ba54SAl Viro c = *(const unsigned char *)name++; 17286a96ba54SAl Viro if (c == '/' || c == '\0') 17296a96ba54SAl Viro return ERR_PTR(-EACCES); 17306a96ba54SAl Viro hash = partial_name_hash(c, hash); 17316a96ba54SAl Viro } 17326a96ba54SAl Viro this.hash = end_name_hash(hash); 17335a202bcdSAl Viro /* 17345a202bcdSAl Viro * See if the low-level filesystem might want 17355a202bcdSAl Viro * to use its own hash.. 17365a202bcdSAl Viro */ 17375a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17385a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17395a202bcdSAl Viro if (err < 0) 17405a202bcdSAl Viro return ERR_PTR(err); 17415a202bcdSAl Viro } 1742eead1911SChristoph Hellwig 174349705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1744057f6c01SJames Morris } 1745057f6c01SJames Morris 17462d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 17472d8f3038SAl Viro struct path *path) 17481da177e4SLinus Torvalds { 17492d8f3038SAl Viro struct nameidata nd; 1750f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 17511da177e4SLinus Torvalds int err = PTR_ERR(tmp); 17521da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 17532d8f3038SAl Viro 17542d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 17552d8f3038SAl Viro 17562d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 17571da177e4SLinus Torvalds putname(tmp); 17582d8f3038SAl Viro if (!err) 17592d8f3038SAl Viro *path = nd.path; 17601da177e4SLinus Torvalds } 17611da177e4SLinus Torvalds return err; 17621da177e4SLinus Torvalds } 17631da177e4SLinus Torvalds 17642ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 17652ad94ae6SAl Viro struct nameidata *nd, char **name) 17662ad94ae6SAl Viro { 17672ad94ae6SAl Viro char *s = getname(path); 17682ad94ae6SAl Viro int error; 17692ad94ae6SAl Viro 17702ad94ae6SAl Viro if (IS_ERR(s)) 17712ad94ae6SAl Viro return PTR_ERR(s); 17722ad94ae6SAl Viro 17732ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 17742ad94ae6SAl Viro if (error) 17752ad94ae6SAl Viro putname(s); 17762ad94ae6SAl Viro else 17772ad94ae6SAl Viro *name = s; 17782ad94ae6SAl Viro 17792ad94ae6SAl Viro return error; 17802ad94ae6SAl Viro } 17812ad94ae6SAl Viro 17821da177e4SLinus Torvalds /* 17831da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 17841da177e4SLinus Torvalds * minimal. 17851da177e4SLinus Torvalds */ 17861da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 17871da177e4SLinus Torvalds { 1788da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1789da9592edSDavid Howells 17901da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 17911da177e4SLinus Torvalds return 0; 1792e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1793e795b717SSerge E. Hallyn goto other_userns; 1794da9592edSDavid Howells if (inode->i_uid == fsuid) 17951da177e4SLinus Torvalds return 0; 1796da9592edSDavid Howells if (dir->i_uid == fsuid) 17971da177e4SLinus Torvalds return 0; 1798e795b717SSerge E. Hallyn 1799e795b717SSerge E. Hallyn other_userns: 1800e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 18011da177e4SLinus Torvalds } 18021da177e4SLinus Torvalds 18031da177e4SLinus Torvalds /* 18041da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18051da177e4SLinus Torvalds * whether the type of victim is right. 18061da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18071da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18081da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18091da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18101da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18111da177e4SLinus Torvalds * a. be owner of dir, or 18121da177e4SLinus Torvalds * b. be owner of victim, or 18131da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18141da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18151da177e4SLinus Torvalds * links pointing to it. 18161da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18171da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18181da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18191da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18201da177e4SLinus Torvalds * nfs_async_unlink(). 18211da177e4SLinus Torvalds */ 1822858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18231da177e4SLinus Torvalds { 18241da177e4SLinus Torvalds int error; 18251da177e4SLinus Torvalds 18261da177e4SLinus Torvalds if (!victim->d_inode) 18271da177e4SLinus Torvalds return -ENOENT; 18281da177e4SLinus Torvalds 18291da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1830cccc6bbaSAl Viro audit_inode_child(victim, dir); 18311da177e4SLinus Torvalds 1832f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18331da177e4SLinus Torvalds if (error) 18341da177e4SLinus Torvalds return error; 18351da177e4SLinus Torvalds if (IS_APPEND(dir)) 18361da177e4SLinus Torvalds return -EPERM; 18371da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1838f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18391da177e4SLinus Torvalds return -EPERM; 18401da177e4SLinus Torvalds if (isdir) { 18411da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18421da177e4SLinus Torvalds return -ENOTDIR; 18431da177e4SLinus Torvalds if (IS_ROOT(victim)) 18441da177e4SLinus Torvalds return -EBUSY; 18451da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18461da177e4SLinus Torvalds return -EISDIR; 18471da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18481da177e4SLinus Torvalds return -ENOENT; 18491da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 18501da177e4SLinus Torvalds return -EBUSY; 18511da177e4SLinus Torvalds return 0; 18521da177e4SLinus Torvalds } 18531da177e4SLinus Torvalds 18541da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 18551da177e4SLinus Torvalds * dir. 18561da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 18571da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 18581da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 18591da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 18601da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 18611da177e4SLinus Torvalds */ 1862a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 18631da177e4SLinus Torvalds { 18641da177e4SLinus Torvalds if (child->d_inode) 18651da177e4SLinus Torvalds return -EEXIST; 18661da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18671da177e4SLinus Torvalds return -ENOENT; 1868f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 18691da177e4SLinus Torvalds } 18701da177e4SLinus Torvalds 18711da177e4SLinus Torvalds /* 18721da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 18731da177e4SLinus Torvalds */ 18741da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 18751da177e4SLinus Torvalds { 18761da177e4SLinus Torvalds struct dentry *p; 18771da177e4SLinus Torvalds 18781da177e4SLinus Torvalds if (p1 == p2) { 1879f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 18801da177e4SLinus Torvalds return NULL; 18811da177e4SLinus Torvalds } 18821da177e4SLinus Torvalds 1883a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18841da177e4SLinus Torvalds 1885e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1886e2761a11SOGAWA Hirofumi if (p) { 1887f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1888f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 18891da177e4SLinus Torvalds return p; 18901da177e4SLinus Torvalds } 18911da177e4SLinus Torvalds 1892e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1893e2761a11SOGAWA Hirofumi if (p) { 1894f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1895f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 18961da177e4SLinus Torvalds return p; 18971da177e4SLinus Torvalds } 18981da177e4SLinus Torvalds 1899f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1900f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19011da177e4SLinus Torvalds return NULL; 19021da177e4SLinus Torvalds } 19031da177e4SLinus Torvalds 19041da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19051da177e4SLinus Torvalds { 19061b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19071da177e4SLinus Torvalds if (p1 != p2) { 19081b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1909a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19101da177e4SLinus Torvalds } 19111da177e4SLinus Torvalds } 19121da177e4SLinus Torvalds 19131da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19141da177e4SLinus Torvalds struct nameidata *nd) 19151da177e4SLinus Torvalds { 1916a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19171da177e4SLinus Torvalds 19181da177e4SLinus Torvalds if (error) 19191da177e4SLinus Torvalds return error; 19201da177e4SLinus Torvalds 1921acfa4380SAl Viro if (!dir->i_op->create) 19221da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19231da177e4SLinus Torvalds mode &= S_IALLUGO; 19241da177e4SLinus Torvalds mode |= S_IFREG; 19251da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19261da177e4SLinus Torvalds if (error) 19271da177e4SLinus Torvalds return error; 19281da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1929a74574aaSStephen Smalley if (!error) 1930f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19311da177e4SLinus Torvalds return error; 19321da177e4SLinus Torvalds } 19331da177e4SLinus Torvalds 193473d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19351da177e4SLinus Torvalds { 19363fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19371da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19381da177e4SLinus Torvalds int error; 19391da177e4SLinus Torvalds 1940bcda7652SAl Viro /* O_PATH? */ 1941bcda7652SAl Viro if (!acc_mode) 1942bcda7652SAl Viro return 0; 1943bcda7652SAl Viro 19441da177e4SLinus Torvalds if (!inode) 19451da177e4SLinus Torvalds return -ENOENT; 19461da177e4SLinus Torvalds 1947c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1948c8fe8f30SChristoph Hellwig case S_IFLNK: 19491da177e4SLinus Torvalds return -ELOOP; 1950c8fe8f30SChristoph Hellwig case S_IFDIR: 1951c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 19521da177e4SLinus Torvalds return -EISDIR; 1953c8fe8f30SChristoph Hellwig break; 1954c8fe8f30SChristoph Hellwig case S_IFBLK: 1955c8fe8f30SChristoph Hellwig case S_IFCHR: 19563fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 19571da177e4SLinus Torvalds return -EACCES; 1958c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1959c8fe8f30SChristoph Hellwig case S_IFIFO: 1960c8fe8f30SChristoph Hellwig case S_IFSOCK: 19611da177e4SLinus Torvalds flag &= ~O_TRUNC; 1962c8fe8f30SChristoph Hellwig break; 19634a3fd211SDave Hansen } 1964b41572e9SDave Hansen 19653fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1966b41572e9SDave Hansen if (error) 1967b41572e9SDave Hansen return error; 19686146f0d5SMimi Zohar 19691da177e4SLinus Torvalds /* 19701da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 19711da177e4SLinus Torvalds */ 19721da177e4SLinus Torvalds if (IS_APPEND(inode)) { 19738737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 19747715b521SAl Viro return -EPERM; 19751da177e4SLinus Torvalds if (flag & O_TRUNC) 19767715b521SAl Viro return -EPERM; 19771da177e4SLinus Torvalds } 19781da177e4SLinus Torvalds 19791da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 19802e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 19817715b521SAl Viro return -EPERM; 19821da177e4SLinus Torvalds 19831da177e4SLinus Torvalds /* 19841da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 19851da177e4SLinus Torvalds */ 1986b65a9cfcSAl Viro return break_lease(inode, flag); 19877715b521SAl Viro } 19887715b521SAl Viro 1989e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 19907715b521SAl Viro { 1991e1181ee6SJeff Layton struct path *path = &filp->f_path; 19927715b521SAl Viro struct inode *inode = path->dentry->d_inode; 19937715b521SAl Viro int error = get_write_access(inode); 19941da177e4SLinus Torvalds if (error) 19957715b521SAl Viro return error; 19961da177e4SLinus Torvalds /* 19971da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 19981da177e4SLinus Torvalds */ 19991da177e4SLinus Torvalds error = locks_verify_locked(inode); 2000be6d3e56SKentaro Takeda if (!error) 2001ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20021da177e4SLinus Torvalds if (!error) { 20037715b521SAl Viro error = do_truncate(path->dentry, 0, 2004d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2005e1181ee6SJeff Layton filp); 20061da177e4SLinus Torvalds } 20071da177e4SLinus Torvalds put_write_access(inode); 2008acd0c935SMimi Zohar return error; 20091da177e4SLinus Torvalds } 20101da177e4SLinus Torvalds 2011d57999e1SDave Hansen /* 2012d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2013d57999e1SDave Hansen * 00 - read-only 2014d57999e1SDave Hansen * 01 - write-only 2015d57999e1SDave Hansen * 10 - read-write 2016d57999e1SDave Hansen * 11 - special 2017d57999e1SDave Hansen * it is changed into 2018d57999e1SDave Hansen * 00 - no permissions needed 2019d57999e1SDave Hansen * 01 - read-permission 2020d57999e1SDave Hansen * 10 - write-permission 2021d57999e1SDave Hansen * 11 - read-write 2022d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2023d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2024d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2025d57999e1SDave Hansen * later). 2026d57999e1SDave Hansen * 2027d57999e1SDave Hansen */ 2028d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2029d57999e1SDave Hansen { 2030d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2031d57999e1SDave Hansen flag++; 2032d57999e1SDave Hansen return flag; 2033d57999e1SDave Hansen } 2034d57999e1SDave Hansen 203531e6b01fSNick Piggin /* 2036fe2d35ffSAl Viro * Handle the last step of open() 203731e6b01fSNick Piggin */ 2038fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2039c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2040fb1cc555SAl Viro { 2041a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20426c0d46c4SAl Viro struct dentry *dentry; 2043ca344a89SAl Viro int open_flag = op->open_flag; 20446c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2045ca344a89SAl Viro int want_write = 0; 2046bcda7652SAl Viro int acc_mode = op->acc_mode; 2047fb1cc555SAl Viro struct file *filp; 204816c2cd71SAl Viro int error; 2049fb1cc555SAl Viro 2050c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2051c3e380b0SAl Viro nd->flags |= op->intent; 2052c3e380b0SAl Viro 20531f36f774SAl Viro switch (nd->last_type) { 20541f36f774SAl Viro case LAST_DOTDOT: 2055176306f5SNeil Brown case LAST_DOT: 2056fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2057fe2d35ffSAl Viro if (error) 2058fe2d35ffSAl Viro return ERR_PTR(error); 20591f36f774SAl Viro /* fallthrough */ 20601f36f774SAl Viro case LAST_ROOT: 20619f1fafeeSAl Viro error = complete_walk(nd); 206216c2cd71SAl Viro if (error) 20639f1fafeeSAl Viro return ERR_PTR(error); 2064fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2065ca344a89SAl Viro if (open_flag & O_CREAT) { 206616c2cd71SAl Viro error = -EISDIR; 20671f36f774SAl Viro goto exit; 2068fe2d35ffSAl Viro } 2069fe2d35ffSAl Viro goto ok; 20701f36f774SAl Viro case LAST_BIND: 20719f1fafeeSAl Viro error = complete_walk(nd); 207216c2cd71SAl Viro if (error) 20739f1fafeeSAl Viro return ERR_PTR(error); 20741f36f774SAl Viro audit_inode(pathname, dir); 20751f36f774SAl Viro goto ok; 20761f36f774SAl Viro } 2077a2c36b45SAl Viro 2078ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2079bcda7652SAl Viro int symlink_ok = 0; 2080fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2081fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2082bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2083bcda7652SAl Viro symlink_ok = 1; 2084fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2085ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2086ce57dfc1SAl Viro !symlink_ok); 2087ce57dfc1SAl Viro if (error < 0) 2088fe2d35ffSAl Viro return ERR_PTR(error); 2089ce57dfc1SAl Viro if (error) /* symlink */ 2090fe2d35ffSAl Viro return NULL; 2091fe2d35ffSAl Viro /* sayonara */ 20929f1fafeeSAl Viro error = complete_walk(nd); 20939f1fafeeSAl Viro if (error) 2094fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2095fe2d35ffSAl Viro 2096fe2d35ffSAl Viro error = -ENOTDIR; 2097fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2098ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2099fe2d35ffSAl Viro goto exit; 2100fe2d35ffSAl Viro } 2101fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2102fe2d35ffSAl Viro goto ok; 2103fe2d35ffSAl Viro } 2104fe2d35ffSAl Viro 2105fe2d35ffSAl Viro /* create side of things */ 21069f1fafeeSAl Viro error = complete_walk(nd); 21079f1fafeeSAl Viro if (error) 21089f1fafeeSAl Viro return ERR_PTR(error); 2109fe2d35ffSAl Viro 2110fe2d35ffSAl Viro audit_inode(pathname, dir); 211116c2cd71SAl Viro error = -EISDIR; 21121f36f774SAl Viro /* trailing slashes? */ 211331e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21141f36f774SAl Viro goto exit; 21151f36f774SAl Viro 2116a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2117a1e28038SAl Viro 21186c0d46c4SAl Viro dentry = lookup_hash(nd); 21196c0d46c4SAl Viro error = PTR_ERR(dentry); 21206c0d46c4SAl Viro if (IS_ERR(dentry)) { 2121fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2122fb1cc555SAl Viro goto exit; 2123fb1cc555SAl Viro } 2124fb1cc555SAl Viro 21256c0d46c4SAl Viro path->dentry = dentry; 21266c0d46c4SAl Viro path->mnt = nd->path.mnt; 21276c0d46c4SAl Viro 2128fb1cc555SAl Viro /* Negative dentry, just create the file */ 21296c0d46c4SAl Viro if (!dentry->d_inode) { 21306c0d46c4SAl Viro int mode = op->mode; 21316c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21326c0d46c4SAl Viro mode &= ~current_umask(); 2133fb1cc555SAl Viro /* 2134fb1cc555SAl Viro * This write is needed to ensure that a 21356c0d46c4SAl Viro * rw->ro transition does not occur between 2136fb1cc555SAl Viro * the time when the file is created and when 2137fb1cc555SAl Viro * a permanent write count is taken through 2138fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2139fb1cc555SAl Viro */ 2140fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2141fb1cc555SAl Viro if (error) 2142fb1cc555SAl Viro goto exit_mutex_unlock; 2143ca344a89SAl Viro want_write = 1; 21449b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2145ca344a89SAl Viro open_flag &= ~O_TRUNC; 21466c0d46c4SAl Viro will_truncate = 0; 2147bcda7652SAl Viro acc_mode = MAY_OPEN; 21486c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 21496c0d46c4SAl Viro if (error) 21506c0d46c4SAl Viro goto exit_mutex_unlock; 21516c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 21526c0d46c4SAl Viro if (error) 21536c0d46c4SAl Viro goto exit_mutex_unlock; 21546c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 21556c0d46c4SAl Viro dput(nd->path.dentry); 21566c0d46c4SAl Viro nd->path.dentry = dentry; 2157ca344a89SAl Viro goto common; 2158fb1cc555SAl Viro } 2159fb1cc555SAl Viro 2160fb1cc555SAl Viro /* 2161fb1cc555SAl Viro * It already exists. 2162fb1cc555SAl Viro */ 2163fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2164fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2165fb1cc555SAl Viro 2166fb1cc555SAl Viro error = -EEXIST; 2167ca344a89SAl Viro if (open_flag & O_EXCL) 2168fb1cc555SAl Viro goto exit_dput; 2169fb1cc555SAl Viro 21709875cf80SDavid Howells error = follow_managed(path, nd->flags); 21719875cf80SDavid Howells if (error < 0) 2172fb1cc555SAl Viro goto exit_dput; 2173fb1cc555SAl Viro 2174fb1cc555SAl Viro error = -ENOENT; 2175fb1cc555SAl Viro if (!path->dentry->d_inode) 2176fb1cc555SAl Viro goto exit_dput; 21779e67f361SAl Viro 21789e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2179fb1cc555SAl Viro return NULL; 2180fb1cc555SAl Viro 2181fb1cc555SAl Viro path_to_nameidata(path, nd); 218231e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2183fb1cc555SAl Viro error = -EISDIR; 218431e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2185fb1cc555SAl Viro goto exit; 218667ee3ad2SAl Viro ok: 21876c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 21886c0d46c4SAl Viro will_truncate = 0; 21896c0d46c4SAl Viro 21900f9d1a10SAl Viro if (will_truncate) { 21910f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 21920f9d1a10SAl Viro if (error) 21930f9d1a10SAl Viro goto exit; 2194ca344a89SAl Viro want_write = 1; 21950f9d1a10SAl Viro } 2196ca344a89SAl Viro common: 2197bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2198ca344a89SAl Viro if (error) 21990f9d1a10SAl Viro goto exit; 22000f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22010f9d1a10SAl Viro if (!IS_ERR(filp)) { 22020f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22030f9d1a10SAl Viro if (error) { 22040f9d1a10SAl Viro fput(filp); 22050f9d1a10SAl Viro filp = ERR_PTR(error); 22060f9d1a10SAl Viro } 22070f9d1a10SAl Viro } 22080f9d1a10SAl Viro if (!IS_ERR(filp)) { 22090f9d1a10SAl Viro if (will_truncate) { 22100f9d1a10SAl Viro error = handle_truncate(filp); 22110f9d1a10SAl Viro if (error) { 22120f9d1a10SAl Viro fput(filp); 22130f9d1a10SAl Viro filp = ERR_PTR(error); 22140f9d1a10SAl Viro } 22150f9d1a10SAl Viro } 22160f9d1a10SAl Viro } 2217ca344a89SAl Viro out: 2218ca344a89SAl Viro if (want_write) 22190f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22200f9d1a10SAl Viro path_put(&nd->path); 2221fb1cc555SAl Viro return filp; 2222fb1cc555SAl Viro 2223fb1cc555SAl Viro exit_mutex_unlock: 2224fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2225fb1cc555SAl Viro exit_dput: 2226fb1cc555SAl Viro path_put_conditional(path, nd); 2227fb1cc555SAl Viro exit: 2228ca344a89SAl Viro filp = ERR_PTR(error); 2229ca344a89SAl Viro goto out; 2230fb1cc555SAl Viro } 2231fb1cc555SAl Viro 223213aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 223373d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22341da177e4SLinus Torvalds { 2235fe2d35ffSAl Viro struct file *base = NULL; 22364a3fd211SDave Hansen struct file *filp; 22379850c056SAl Viro struct path path; 223813aab428SAl Viro int error; 223931e6b01fSNick Piggin 224031e6b01fSNick Piggin filp = get_empty_filp(); 224131e6b01fSNick Piggin if (!filp) 224231e6b01fSNick Piggin return ERR_PTR(-ENFILE); 224331e6b01fSNick Piggin 224447c805dcSAl Viro filp->f_flags = op->open_flag; 224573d049a4SAl Viro nd->intent.open.file = filp; 224673d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 224773d049a4SAl Viro nd->intent.open.create_mode = op->mode; 224831e6b01fSNick Piggin 224973d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 225031e6b01fSNick Piggin if (unlikely(error)) 225113aab428SAl Viro goto out_filp; 225231e6b01fSNick Piggin 2253fe2d35ffSAl Viro current->total_link_count = 0; 225473d049a4SAl Viro error = link_path_walk(pathname, nd); 225531e6b01fSNick Piggin if (unlikely(error)) 225631e6b01fSNick Piggin goto out_filp; 22571da177e4SLinus Torvalds 225873d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2259806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 22607b9337aaSNick Piggin struct path link = path; 2261def4af30SAl Viro void *cookie; 2262574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 226373d049a4SAl Viro path_put_conditional(&path, nd); 226473d049a4SAl Viro path_put(&nd->path); 226540b39136SAl Viro filp = ERR_PTR(-ELOOP); 226640b39136SAl Viro break; 226740b39136SAl Viro } 226873d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 226973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2270574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2271c3e380b0SAl Viro if (unlikely(error)) 2272f1afe9efSAl Viro filp = ERR_PTR(error); 2273c3e380b0SAl Viro else 227473d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2275574197e0SAl Viro put_link(nd, &link, cookie); 2276806b681cSAl Viro } 227710fa8e62SAl Viro out: 227873d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 227973d049a4SAl Viro path_put(&nd->root); 2280fe2d35ffSAl Viro if (base) 2281fe2d35ffSAl Viro fput(base); 228273d049a4SAl Viro release_open_intent(nd); 228310fa8e62SAl Viro return filp; 22841da177e4SLinus Torvalds 228531e6b01fSNick Piggin out_filp: 228610fa8e62SAl Viro filp = ERR_PTR(error); 228710fa8e62SAl Viro goto out; 2288de459215SKirill Korotaev } 22891da177e4SLinus Torvalds 229013aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 229113aab428SAl Viro const struct open_flags *op, int flags) 229213aab428SAl Viro { 229373d049a4SAl Viro struct nameidata nd; 229413aab428SAl Viro struct file *filp; 229513aab428SAl Viro 229673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 229713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 229873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 229913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 230073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 230113aab428SAl Viro return filp; 230213aab428SAl Viro } 230313aab428SAl Viro 230473d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 230573d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 230673d049a4SAl Viro { 230773d049a4SAl Viro struct nameidata nd; 230873d049a4SAl Viro struct file *file; 230973d049a4SAl Viro 231073d049a4SAl Viro nd.root.mnt = mnt; 231173d049a4SAl Viro nd.root.dentry = dentry; 231273d049a4SAl Viro 231373d049a4SAl Viro flags |= LOOKUP_ROOT; 231473d049a4SAl Viro 2315bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 231673d049a4SAl Viro return ERR_PTR(-ELOOP); 231773d049a4SAl Viro 231873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 231973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 232073d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 232173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 232273d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 232373d049a4SAl Viro return file; 232473d049a4SAl Viro } 232573d049a4SAl Viro 23261da177e4SLinus Torvalds /** 23271da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23281da177e4SLinus Torvalds * @nd: nameidata info 23291da177e4SLinus Torvalds * @is_dir: directory flag 23301da177e4SLinus Torvalds * 23311da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23321da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2333c663e5d8SChristoph Hellwig * 23344ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23351da177e4SLinus Torvalds */ 23361da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23371da177e4SLinus Torvalds { 2338c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23391da177e4SLinus Torvalds 23404ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2341c663e5d8SChristoph Hellwig /* 2342c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2343c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2344c663e5d8SChristoph Hellwig */ 23451da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23461da177e4SLinus Torvalds goto fail; 23471da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 23483516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2349a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2350c663e5d8SChristoph Hellwig 2351c663e5d8SChristoph Hellwig /* 2352c663e5d8SChristoph Hellwig * Do the final lookup. 2353c663e5d8SChristoph Hellwig */ 235449705b77SChristoph Hellwig dentry = lookup_hash(nd); 23551da177e4SLinus Torvalds if (IS_ERR(dentry)) 23561da177e4SLinus Torvalds goto fail; 2357c663e5d8SChristoph Hellwig 2358e9baf6e5SAl Viro if (dentry->d_inode) 2359e9baf6e5SAl Viro goto eexist; 2360c663e5d8SChristoph Hellwig /* 2361c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2362c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2363c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2364c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2365c663e5d8SChristoph Hellwig */ 2366e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 23671da177e4SLinus Torvalds dput(dentry); 23681da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2369e9baf6e5SAl Viro } 2370e9baf6e5SAl Viro return dentry; 2371e9baf6e5SAl Viro eexist: 2372e9baf6e5SAl Viro dput(dentry); 2373e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 23741da177e4SLinus Torvalds fail: 23751da177e4SLinus Torvalds return dentry; 23761da177e4SLinus Torvalds } 2377f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 23781da177e4SLinus Torvalds 23791da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 23801da177e4SLinus Torvalds { 2381a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23821da177e4SLinus Torvalds 23831da177e4SLinus Torvalds if (error) 23841da177e4SLinus Torvalds return error; 23851da177e4SLinus Torvalds 2386e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2387e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 23881da177e4SLinus Torvalds return -EPERM; 23891da177e4SLinus Torvalds 2390acfa4380SAl Viro if (!dir->i_op->mknod) 23911da177e4SLinus Torvalds return -EPERM; 23921da177e4SLinus Torvalds 239308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 239408ce5f16SSerge E. Hallyn if (error) 239508ce5f16SSerge E. Hallyn return error; 239608ce5f16SSerge E. Hallyn 23971da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 23981da177e4SLinus Torvalds if (error) 23991da177e4SLinus Torvalds return error; 24001da177e4SLinus Torvalds 24011da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2402a74574aaSStephen Smalley if (!error) 2403f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24041da177e4SLinus Torvalds return error; 24051da177e4SLinus Torvalds } 24061da177e4SLinus Torvalds 2407463c3197SDave Hansen static int may_mknod(mode_t mode) 2408463c3197SDave Hansen { 2409463c3197SDave Hansen switch (mode & S_IFMT) { 2410463c3197SDave Hansen case S_IFREG: 2411463c3197SDave Hansen case S_IFCHR: 2412463c3197SDave Hansen case S_IFBLK: 2413463c3197SDave Hansen case S_IFIFO: 2414463c3197SDave Hansen case S_IFSOCK: 2415463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2416463c3197SDave Hansen return 0; 2417463c3197SDave Hansen case S_IFDIR: 2418463c3197SDave Hansen return -EPERM; 2419463c3197SDave Hansen default: 2420463c3197SDave Hansen return -EINVAL; 2421463c3197SDave Hansen } 2422463c3197SDave Hansen } 2423463c3197SDave Hansen 24242e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24252e4d0924SHeiko Carstens unsigned, dev) 24261da177e4SLinus Torvalds { 24272ad94ae6SAl Viro int error; 24281da177e4SLinus Torvalds char *tmp; 24291da177e4SLinus Torvalds struct dentry *dentry; 24301da177e4SLinus Torvalds struct nameidata nd; 24311da177e4SLinus Torvalds 24321da177e4SLinus Torvalds if (S_ISDIR(mode)) 24331da177e4SLinus Torvalds return -EPERM; 24341da177e4SLinus Torvalds 24352ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24361da177e4SLinus Torvalds if (error) 24372ad94ae6SAl Viro return error; 24382ad94ae6SAl Viro 24391da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2440463c3197SDave Hansen if (IS_ERR(dentry)) { 24411da177e4SLinus Torvalds error = PTR_ERR(dentry); 2442463c3197SDave Hansen goto out_unlock; 2443463c3197SDave Hansen } 24444ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2445ce3b0f8dSAl Viro mode &= ~current_umask(); 2446463c3197SDave Hansen error = may_mknod(mode); 2447463c3197SDave Hansen if (error) 2448463c3197SDave Hansen goto out_dput; 2449463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2450463c3197SDave Hansen if (error) 2451463c3197SDave Hansen goto out_dput; 2452be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2453be6d3e56SKentaro Takeda if (error) 2454be6d3e56SKentaro Takeda goto out_drop_write; 24551da177e4SLinus Torvalds switch (mode & S_IFMT) { 24561da177e4SLinus Torvalds case 0: case S_IFREG: 24574ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 24581da177e4SLinus Torvalds break; 24591da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 24604ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 24611da177e4SLinus Torvalds new_decode_dev(dev)); 24621da177e4SLinus Torvalds break; 24631da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 24644ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 24651da177e4SLinus Torvalds break; 24661da177e4SLinus Torvalds } 2467be6d3e56SKentaro Takeda out_drop_write: 2468463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2469463c3197SDave Hansen out_dput: 24701da177e4SLinus Torvalds dput(dentry); 2471463c3197SDave Hansen out_unlock: 24724ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24731d957f9bSJan Blunck path_put(&nd.path); 24741da177e4SLinus Torvalds putname(tmp); 24751da177e4SLinus Torvalds 24761da177e4SLinus Torvalds return error; 24771da177e4SLinus Torvalds } 24781da177e4SLinus Torvalds 24793480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 24805590ff0dSUlrich Drepper { 24815590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 24825590ff0dSUlrich Drepper } 24835590ff0dSUlrich Drepper 24841da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 24851da177e4SLinus Torvalds { 2486a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24871da177e4SLinus Torvalds 24881da177e4SLinus Torvalds if (error) 24891da177e4SLinus Torvalds return error; 24901da177e4SLinus Torvalds 2491acfa4380SAl Viro if (!dir->i_op->mkdir) 24921da177e4SLinus Torvalds return -EPERM; 24931da177e4SLinus Torvalds 24941da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 24951da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 24961da177e4SLinus Torvalds if (error) 24971da177e4SLinus Torvalds return error; 24981da177e4SLinus Torvalds 24991da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2500a74574aaSStephen Smalley if (!error) 2501f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25021da177e4SLinus Torvalds return error; 25031da177e4SLinus Torvalds } 25041da177e4SLinus Torvalds 25052e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25061da177e4SLinus Torvalds { 25071da177e4SLinus Torvalds int error = 0; 25081da177e4SLinus Torvalds char * tmp; 25096902d925SDave Hansen struct dentry *dentry; 25106902d925SDave Hansen struct nameidata nd; 25111da177e4SLinus Torvalds 25122ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25132ad94ae6SAl Viro if (error) 25146902d925SDave Hansen goto out_err; 25151da177e4SLinus Torvalds 25161da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25171da177e4SLinus Torvalds error = PTR_ERR(dentry); 25186902d925SDave Hansen if (IS_ERR(dentry)) 25196902d925SDave Hansen goto out_unlock; 25206902d925SDave Hansen 25214ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2522ce3b0f8dSAl Viro mode &= ~current_umask(); 2523463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2524463c3197SDave Hansen if (error) 2525463c3197SDave Hansen goto out_dput; 2526be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2527be6d3e56SKentaro Takeda if (error) 2528be6d3e56SKentaro Takeda goto out_drop_write; 25294ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2530be6d3e56SKentaro Takeda out_drop_write: 2531463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2532463c3197SDave Hansen out_dput: 25331da177e4SLinus Torvalds dput(dentry); 25346902d925SDave Hansen out_unlock: 25354ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25361d957f9bSJan Blunck path_put(&nd.path); 25371da177e4SLinus Torvalds putname(tmp); 25386902d925SDave Hansen out_err: 25391da177e4SLinus Torvalds return error; 25401da177e4SLinus Torvalds } 25411da177e4SLinus Torvalds 25423cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25435590ff0dSUlrich Drepper { 25445590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25455590ff0dSUlrich Drepper } 25465590ff0dSUlrich Drepper 25471da177e4SLinus Torvalds /* 2548a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2549a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2550a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2551a71905f0SSage Weil * then we drop the dentry now. 25521da177e4SLinus Torvalds * 25531da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 25541da177e4SLinus Torvalds * do a 25551da177e4SLinus Torvalds * 25561da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 25571da177e4SLinus Torvalds * return -EBUSY; 25581da177e4SLinus Torvalds * 25591da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 25601da177e4SLinus Torvalds * that is still in use by something else.. 25611da177e4SLinus Torvalds */ 25621da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 25631da177e4SLinus Torvalds { 25641da177e4SLinus Torvalds shrink_dcache_parent(dentry); 25651da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 256664252c75SSage Weil if (dentry->d_count == 1) 25671da177e4SLinus Torvalds __d_drop(dentry); 25681da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 25691da177e4SLinus Torvalds } 25701da177e4SLinus Torvalds 25711da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 25721da177e4SLinus Torvalds { 25731da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 25741da177e4SLinus Torvalds 25751da177e4SLinus Torvalds if (error) 25761da177e4SLinus Torvalds return error; 25771da177e4SLinus Torvalds 2578acfa4380SAl Viro if (!dir->i_op->rmdir) 25791da177e4SLinus Torvalds return -EPERM; 25801da177e4SLinus Torvalds 25811b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2582912dbc15SSage Weil 25831da177e4SLinus Torvalds error = -EBUSY; 2584912dbc15SSage Weil if (d_mountpoint(dentry)) 2585912dbc15SSage Weil goto out; 2586912dbc15SSage Weil 25871da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2588912dbc15SSage Weil if (error) 2589912dbc15SSage Weil goto out; 2590912dbc15SSage Weil 25913cebde24SSage Weil shrink_dcache_parent(dentry); 25921da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2593912dbc15SSage Weil if (error) 2594912dbc15SSage Weil goto out; 2595912dbc15SSage Weil 25961da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2597d83c49f3SAl Viro dont_mount(dentry); 25981da177e4SLinus Torvalds 2599912dbc15SSage Weil out: 2600912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 2601912dbc15SSage Weil if (!error) 2602912dbc15SSage Weil d_delete(dentry); 26031da177e4SLinus Torvalds return error; 26041da177e4SLinus Torvalds } 26051da177e4SLinus Torvalds 26065590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26071da177e4SLinus Torvalds { 26081da177e4SLinus Torvalds int error = 0; 26091da177e4SLinus Torvalds char * name; 26101da177e4SLinus Torvalds struct dentry *dentry; 26111da177e4SLinus Torvalds struct nameidata nd; 26121da177e4SLinus Torvalds 26132ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26141da177e4SLinus Torvalds if (error) 26152ad94ae6SAl Viro return error; 26161da177e4SLinus Torvalds 26171da177e4SLinus Torvalds switch(nd.last_type) { 26181da177e4SLinus Torvalds case LAST_DOTDOT: 26191da177e4SLinus Torvalds error = -ENOTEMPTY; 26201da177e4SLinus Torvalds goto exit1; 26211da177e4SLinus Torvalds case LAST_DOT: 26221da177e4SLinus Torvalds error = -EINVAL; 26231da177e4SLinus Torvalds goto exit1; 26241da177e4SLinus Torvalds case LAST_ROOT: 26251da177e4SLinus Torvalds error = -EBUSY; 26261da177e4SLinus Torvalds goto exit1; 26271da177e4SLinus Torvalds } 26280612d9fbSOGAWA Hirofumi 26290612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26300612d9fbSOGAWA Hirofumi 26314ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 263249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26331da177e4SLinus Torvalds error = PTR_ERR(dentry); 26346902d925SDave Hansen if (IS_ERR(dentry)) 26356902d925SDave Hansen goto exit2; 2636e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2637e6bc45d6STheodore Ts'o error = -ENOENT; 2638e6bc45d6STheodore Ts'o goto exit3; 2639e6bc45d6STheodore Ts'o } 26400622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26410622753bSDave Hansen if (error) 26420622753bSDave Hansen goto exit3; 2643be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2644be6d3e56SKentaro Takeda if (error) 2645be6d3e56SKentaro Takeda goto exit4; 26464ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2647be6d3e56SKentaro Takeda exit4: 26480622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26490622753bSDave Hansen exit3: 26501da177e4SLinus Torvalds dput(dentry); 26516902d925SDave Hansen exit2: 26524ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26531da177e4SLinus Torvalds exit1: 26541d957f9bSJan Blunck path_put(&nd.path); 26551da177e4SLinus Torvalds putname(name); 26561da177e4SLinus Torvalds return error; 26571da177e4SLinus Torvalds } 26581da177e4SLinus Torvalds 26593cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 26605590ff0dSUlrich Drepper { 26615590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 26625590ff0dSUlrich Drepper } 26635590ff0dSUlrich Drepper 26641da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 26651da177e4SLinus Torvalds { 26661da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 26671da177e4SLinus Torvalds 26681da177e4SLinus Torvalds if (error) 26691da177e4SLinus Torvalds return error; 26701da177e4SLinus Torvalds 2671acfa4380SAl Viro if (!dir->i_op->unlink) 26721da177e4SLinus Torvalds return -EPERM; 26731da177e4SLinus Torvalds 26741b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26751da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26761da177e4SLinus Torvalds error = -EBUSY; 26771da177e4SLinus Torvalds else { 26781da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2679bec1052eSAl Viro if (!error) { 26801da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2681bec1052eSAl Viro if (!error) 2682d83c49f3SAl Viro dont_mount(dentry); 2683bec1052eSAl Viro } 26841da177e4SLinus Torvalds } 26851b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26861da177e4SLinus Torvalds 26871da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 26881da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2689ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 26901da177e4SLinus Torvalds d_delete(dentry); 26911da177e4SLinus Torvalds } 26920eeca283SRobert Love 26931da177e4SLinus Torvalds return error; 26941da177e4SLinus Torvalds } 26951da177e4SLinus Torvalds 26961da177e4SLinus Torvalds /* 26971da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 26981b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 26991da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27001da177e4SLinus Torvalds * while waiting on the I/O. 27011da177e4SLinus Torvalds */ 27025590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27031da177e4SLinus Torvalds { 27042ad94ae6SAl Viro int error; 27051da177e4SLinus Torvalds char *name; 27061da177e4SLinus Torvalds struct dentry *dentry; 27071da177e4SLinus Torvalds struct nameidata nd; 27081da177e4SLinus Torvalds struct inode *inode = NULL; 27091da177e4SLinus Torvalds 27102ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27111da177e4SLinus Torvalds if (error) 27122ad94ae6SAl Viro return error; 27132ad94ae6SAl Viro 27141da177e4SLinus Torvalds error = -EISDIR; 27151da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27161da177e4SLinus Torvalds goto exit1; 27170612d9fbSOGAWA Hirofumi 27180612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27190612d9fbSOGAWA Hirofumi 27204ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 272149705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27221da177e4SLinus Torvalds error = PTR_ERR(dentry); 27231da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27241da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 272550338b88STörök Edwin if (nd.last.name[nd.last.len]) 272650338b88STörök Edwin goto slashes; 27271da177e4SLinus Torvalds inode = dentry->d_inode; 272850338b88STörök Edwin if (!inode) 2729e6bc45d6STheodore Ts'o goto slashes; 27307de9c6eeSAl Viro ihold(inode); 27310622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27320622753bSDave Hansen if (error) 27330622753bSDave Hansen goto exit2; 2734be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2735be6d3e56SKentaro Takeda if (error) 2736be6d3e56SKentaro Takeda goto exit3; 27374ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2738be6d3e56SKentaro Takeda exit3: 27390622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27401da177e4SLinus Torvalds exit2: 27411da177e4SLinus Torvalds dput(dentry); 27421da177e4SLinus Torvalds } 27434ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27441da177e4SLinus Torvalds if (inode) 27451da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27461da177e4SLinus Torvalds exit1: 27471d957f9bSJan Blunck path_put(&nd.path); 27481da177e4SLinus Torvalds putname(name); 27491da177e4SLinus Torvalds return error; 27501da177e4SLinus Torvalds 27511da177e4SLinus Torvalds slashes: 27521da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27531da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 27541da177e4SLinus Torvalds goto exit2; 27551da177e4SLinus Torvalds } 27561da177e4SLinus Torvalds 27572e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 27585590ff0dSUlrich Drepper { 27595590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 27605590ff0dSUlrich Drepper return -EINVAL; 27615590ff0dSUlrich Drepper 27625590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 27635590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 27645590ff0dSUlrich Drepper 27655590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 27665590ff0dSUlrich Drepper } 27675590ff0dSUlrich Drepper 27683480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 27695590ff0dSUlrich Drepper { 27705590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 27715590ff0dSUlrich Drepper } 27725590ff0dSUlrich Drepper 2773db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 27741da177e4SLinus Torvalds { 2775a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds if (error) 27781da177e4SLinus Torvalds return error; 27791da177e4SLinus Torvalds 2780acfa4380SAl Viro if (!dir->i_op->symlink) 27811da177e4SLinus Torvalds return -EPERM; 27821da177e4SLinus Torvalds 27831da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 27841da177e4SLinus Torvalds if (error) 27851da177e4SLinus Torvalds return error; 27861da177e4SLinus Torvalds 27871da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2788a74574aaSStephen Smalley if (!error) 2789f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27901da177e4SLinus Torvalds return error; 27911da177e4SLinus Torvalds } 27921da177e4SLinus Torvalds 27932e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 27942e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 27951da177e4SLinus Torvalds { 27962ad94ae6SAl Viro int error; 27971da177e4SLinus Torvalds char *from; 27981da177e4SLinus Torvalds char *to; 27996902d925SDave Hansen struct dentry *dentry; 28006902d925SDave Hansen struct nameidata nd; 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds from = getname(oldname); 28031da177e4SLinus Torvalds if (IS_ERR(from)) 28041da177e4SLinus Torvalds return PTR_ERR(from); 28052ad94ae6SAl Viro 28062ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28072ad94ae6SAl Viro if (error) 28086902d925SDave Hansen goto out_putname; 28091da177e4SLinus Torvalds 28101da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28111da177e4SLinus Torvalds error = PTR_ERR(dentry); 28126902d925SDave Hansen if (IS_ERR(dentry)) 28136902d925SDave Hansen goto out_unlock; 28146902d925SDave Hansen 281575c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 281675c3f29dSDave Hansen if (error) 281775c3f29dSDave Hansen goto out_dput; 2818be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2819be6d3e56SKentaro Takeda if (error) 2820be6d3e56SKentaro Takeda goto out_drop_write; 2821db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2822be6d3e56SKentaro Takeda out_drop_write: 282375c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 282475c3f29dSDave Hansen out_dput: 28251da177e4SLinus Torvalds dput(dentry); 28266902d925SDave Hansen out_unlock: 28274ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28281d957f9bSJan Blunck path_put(&nd.path); 28291da177e4SLinus Torvalds putname(to); 28306902d925SDave Hansen out_putname: 28311da177e4SLinus Torvalds putname(from); 28321da177e4SLinus Torvalds return error; 28331da177e4SLinus Torvalds } 28341da177e4SLinus Torvalds 28353480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28365590ff0dSUlrich Drepper { 28375590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28385590ff0dSUlrich Drepper } 28395590ff0dSUlrich Drepper 28401da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28411da177e4SLinus Torvalds { 28421da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28431da177e4SLinus Torvalds int error; 28441da177e4SLinus Torvalds 28451da177e4SLinus Torvalds if (!inode) 28461da177e4SLinus Torvalds return -ENOENT; 28471da177e4SLinus Torvalds 2848a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28491da177e4SLinus Torvalds if (error) 28501da177e4SLinus Torvalds return error; 28511da177e4SLinus Torvalds 28521da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28531da177e4SLinus Torvalds return -EXDEV; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds /* 28561da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 28571da177e4SLinus Torvalds */ 28581da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 28591da177e4SLinus Torvalds return -EPERM; 2860acfa4380SAl Viro if (!dir->i_op->link) 28611da177e4SLinus Torvalds return -EPERM; 28627e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 28631da177e4SLinus Torvalds return -EPERM; 28641da177e4SLinus Torvalds 28651da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 28661da177e4SLinus Torvalds if (error) 28671da177e4SLinus Torvalds return error; 28681da177e4SLinus Torvalds 28697e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2870aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2871aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2872aae8a97dSAneesh Kumar K.V error = -ENOENT; 2873aae8a97dSAneesh Kumar K.V else 28741da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 28757e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2876e31e14ecSStephen Smalley if (!error) 28777e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 28781da177e4SLinus Torvalds return error; 28791da177e4SLinus Torvalds } 28801da177e4SLinus Torvalds 28811da177e4SLinus Torvalds /* 28821da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 28831da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 28841da177e4SLinus Torvalds * newname. --KAB 28851da177e4SLinus Torvalds * 28861da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 28871da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 28881da177e4SLinus Torvalds * and other special files. --ADM 28891da177e4SLinus Torvalds */ 28902e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 28912e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 28921da177e4SLinus Torvalds { 28931da177e4SLinus Torvalds struct dentry *new_dentry; 28942d8f3038SAl Viro struct nameidata nd; 28952d8f3038SAl Viro struct path old_path; 289611a7b371SAneesh Kumar K.V int how = 0; 28971da177e4SLinus Torvalds int error; 28981da177e4SLinus Torvalds char *to; 28991da177e4SLinus Torvalds 290011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2901c04030e1SUlrich Drepper return -EINVAL; 290211a7b371SAneesh Kumar K.V /* 290311a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 290411a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 290511a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 290611a7b371SAneesh Kumar K.V */ 290711a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 290811a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 290911a7b371SAneesh Kumar K.V return -ENOENT; 291011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 291111a7b371SAneesh Kumar K.V } 2912c04030e1SUlrich Drepper 291311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 291411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 291511a7b371SAneesh Kumar K.V 291611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29171da177e4SLinus Torvalds if (error) 29182ad94ae6SAl Viro return error; 29192ad94ae6SAl Viro 29202ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29211da177e4SLinus Torvalds if (error) 29221da177e4SLinus Torvalds goto out; 29231da177e4SLinus Torvalds error = -EXDEV; 29242d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29251da177e4SLinus Torvalds goto out_release; 29261da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29271da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29286902d925SDave Hansen if (IS_ERR(new_dentry)) 29296902d925SDave Hansen goto out_unlock; 293075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 293175c3f29dSDave Hansen if (error) 293275c3f29dSDave Hansen goto out_dput; 2933be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2934be6d3e56SKentaro Takeda if (error) 2935be6d3e56SKentaro Takeda goto out_drop_write; 29362d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2937be6d3e56SKentaro Takeda out_drop_write: 293875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 293975c3f29dSDave Hansen out_dput: 29401da177e4SLinus Torvalds dput(new_dentry); 29416902d925SDave Hansen out_unlock: 29424ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29431da177e4SLinus Torvalds out_release: 29441d957f9bSJan Blunck path_put(&nd.path); 29452ad94ae6SAl Viro putname(to); 29461da177e4SLinus Torvalds out: 29472d8f3038SAl Viro path_put(&old_path); 29481da177e4SLinus Torvalds 29491da177e4SLinus Torvalds return error; 29501da177e4SLinus Torvalds } 29511da177e4SLinus Torvalds 29523480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29535590ff0dSUlrich Drepper { 2954c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29555590ff0dSUlrich Drepper } 29565590ff0dSUlrich Drepper 29571da177e4SLinus Torvalds /* 29581da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29591da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29601da177e4SLinus Torvalds * Problems: 29611da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29621da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29631da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2964a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29651da177e4SLinus Torvalds * story. 29661da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29671b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29681da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29691da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2970a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 29711da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 29721da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 29731da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2974a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 29751da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 29761da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 29771da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 2978e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 29791b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 29801da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 2981c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 29821da177e4SLinus Torvalds * locking]. 29831da177e4SLinus Torvalds */ 298475c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 29851da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 29861da177e4SLinus Torvalds { 29871da177e4SLinus Torvalds int error = 0; 29889055cba7SSage Weil struct inode *target = new_dentry->d_inode; 29891da177e4SLinus Torvalds 29901da177e4SLinus Torvalds /* 29911da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 29921da177e4SLinus Torvalds * we'll need to flip '..'. 29931da177e4SLinus Torvalds */ 29941da177e4SLinus Torvalds if (new_dir != old_dir) { 2995f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 29961da177e4SLinus Torvalds if (error) 29971da177e4SLinus Torvalds return error; 29981da177e4SLinus Torvalds } 29991da177e4SLinus Torvalds 30001da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30011da177e4SLinus Torvalds if (error) 30021da177e4SLinus Torvalds return error; 30031da177e4SLinus Torvalds 3004d83c49f3SAl Viro if (target) 30051b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30069055cba7SSage Weil 30071da177e4SLinus Torvalds error = -EBUSY; 30089055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 30099055cba7SSage Weil goto out; 30109055cba7SSage Weil 30113cebde24SSage Weil if (target) 30123cebde24SSage Weil shrink_dcache_parent(new_dentry); 30131da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30149055cba7SSage Weil if (error) 30159055cba7SSage Weil goto out; 30169055cba7SSage Weil 30171da177e4SLinus Torvalds if (target) { 30181da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3019d83c49f3SAl Viro dont_mount(new_dentry); 3020d83c49f3SAl Viro } 30219055cba7SSage Weil out: 30229055cba7SSage Weil if (target) 30231b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 3024e31e14ecSStephen Smalley if (!error) 3025349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30261da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30271da177e4SLinus Torvalds return error; 30281da177e4SLinus Torvalds } 30291da177e4SLinus Torvalds 303075c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30311da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30321da177e4SLinus Torvalds { 303351892bbbSSage Weil struct inode *target = new_dentry->d_inode; 30341da177e4SLinus Torvalds int error; 30351da177e4SLinus Torvalds 30361da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30371da177e4SLinus Torvalds if (error) 30381da177e4SLinus Torvalds return error; 30391da177e4SLinus Torvalds 30401da177e4SLinus Torvalds dget(new_dentry); 30411da177e4SLinus Torvalds if (target) 30421b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 304351892bbbSSage Weil 30441da177e4SLinus Torvalds error = -EBUSY; 304551892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 304651892bbbSSage Weil goto out; 304751892bbbSSage Weil 30481da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 304951892bbbSSage Weil if (error) 305051892bbbSSage Weil goto out; 305151892bbbSSage Weil 3052bec1052eSAl Viro if (target) 3053d83c49f3SAl Viro dont_mount(new_dentry); 3054349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30551da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 305651892bbbSSage Weil out: 30571da177e4SLinus Torvalds if (target) 30581b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30591da177e4SLinus Torvalds dput(new_dentry); 30601da177e4SLinus Torvalds return error; 30611da177e4SLinus Torvalds } 30621da177e4SLinus Torvalds 30631da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30641da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30651da177e4SLinus Torvalds { 30661da177e4SLinus Torvalds int error; 30671da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 306859b0df21SEric Paris const unsigned char *old_name; 30691da177e4SLinus Torvalds 30701da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 30711da177e4SLinus Torvalds return 0; 30721da177e4SLinus Torvalds 30731da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 30741da177e4SLinus Torvalds if (error) 30751da177e4SLinus Torvalds return error; 30761da177e4SLinus Torvalds 30771da177e4SLinus Torvalds if (!new_dentry->d_inode) 3078a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 30791da177e4SLinus Torvalds else 30801da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 30811da177e4SLinus Torvalds if (error) 30821da177e4SLinus Torvalds return error; 30831da177e4SLinus Torvalds 3084acfa4380SAl Viro if (!old_dir->i_op->rename) 30851da177e4SLinus Torvalds return -EPERM; 30861da177e4SLinus Torvalds 30870eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 30880eeca283SRobert Love 30891da177e4SLinus Torvalds if (is_dir) 30901da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 30911da177e4SLinus Torvalds else 30921da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3093123df294SAl Viro if (!error) 3094123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 30955a190ae6SAl Viro new_dentry->d_inode, old_dentry); 30960eeca283SRobert Love fsnotify_oldname_free(old_name); 30970eeca283SRobert Love 30981da177e4SLinus Torvalds return error; 30991da177e4SLinus Torvalds } 31001da177e4SLinus Torvalds 31012e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31022e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31031da177e4SLinus Torvalds { 31041da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31051da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31061da177e4SLinus Torvalds struct dentry *trap; 31071da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31082ad94ae6SAl Viro char *from; 31092ad94ae6SAl Viro char *to; 31102ad94ae6SAl Viro int error; 31111da177e4SLinus Torvalds 31122ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31131da177e4SLinus Torvalds if (error) 31141da177e4SLinus Torvalds goto exit; 31151da177e4SLinus Torvalds 31162ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31171da177e4SLinus Torvalds if (error) 31181da177e4SLinus Torvalds goto exit1; 31191da177e4SLinus Torvalds 31201da177e4SLinus Torvalds error = -EXDEV; 31214ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31221da177e4SLinus Torvalds goto exit2; 31231da177e4SLinus Torvalds 31244ac91378SJan Blunck old_dir = oldnd.path.dentry; 31251da177e4SLinus Torvalds error = -EBUSY; 31261da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31271da177e4SLinus Torvalds goto exit2; 31281da177e4SLinus Torvalds 31294ac91378SJan Blunck new_dir = newnd.path.dentry; 31301da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31311da177e4SLinus Torvalds goto exit2; 31321da177e4SLinus Torvalds 31330612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31340612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31354e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31360612d9fbSOGAWA Hirofumi 31371da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31381da177e4SLinus Torvalds 313949705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31401da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31411da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31421da177e4SLinus Torvalds goto exit3; 31431da177e4SLinus Torvalds /* source must exist */ 31441da177e4SLinus Torvalds error = -ENOENT; 31451da177e4SLinus Torvalds if (!old_dentry->d_inode) 31461da177e4SLinus Torvalds goto exit4; 31471da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31481da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31491da177e4SLinus Torvalds error = -ENOTDIR; 31501da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31511da177e4SLinus Torvalds goto exit4; 31521da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31531da177e4SLinus Torvalds goto exit4; 31541da177e4SLinus Torvalds } 31551da177e4SLinus Torvalds /* source should not be ancestor of target */ 31561da177e4SLinus Torvalds error = -EINVAL; 31571da177e4SLinus Torvalds if (old_dentry == trap) 31581da177e4SLinus Torvalds goto exit4; 315949705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31601da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31611da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31621da177e4SLinus Torvalds goto exit4; 31631da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31641da177e4SLinus Torvalds error = -ENOTEMPTY; 31651da177e4SLinus Torvalds if (new_dentry == trap) 31661da177e4SLinus Torvalds goto exit5; 31671da177e4SLinus Torvalds 31689079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 31699079b1ebSDave Hansen if (error) 31709079b1ebSDave Hansen goto exit5; 3171be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3172be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3173be6d3e56SKentaro Takeda if (error) 3174be6d3e56SKentaro Takeda goto exit6; 31751da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 31761da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3177be6d3e56SKentaro Takeda exit6: 31789079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 31791da177e4SLinus Torvalds exit5: 31801da177e4SLinus Torvalds dput(new_dentry); 31811da177e4SLinus Torvalds exit4: 31821da177e4SLinus Torvalds dput(old_dentry); 31831da177e4SLinus Torvalds exit3: 31841da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 31851da177e4SLinus Torvalds exit2: 31861d957f9bSJan Blunck path_put(&newnd.path); 31872ad94ae6SAl Viro putname(to); 31881da177e4SLinus Torvalds exit1: 31891d957f9bSJan Blunck path_put(&oldnd.path); 31901da177e4SLinus Torvalds putname(from); 31912ad94ae6SAl Viro exit: 31921da177e4SLinus Torvalds return error; 31931da177e4SLinus Torvalds } 31941da177e4SLinus Torvalds 3195a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 31965590ff0dSUlrich Drepper { 31975590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 31985590ff0dSUlrich Drepper } 31995590ff0dSUlrich Drepper 32001da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32011da177e4SLinus Torvalds { 32021da177e4SLinus Torvalds int len; 32031da177e4SLinus Torvalds 32041da177e4SLinus Torvalds len = PTR_ERR(link); 32051da177e4SLinus Torvalds if (IS_ERR(link)) 32061da177e4SLinus Torvalds goto out; 32071da177e4SLinus Torvalds 32081da177e4SLinus Torvalds len = strlen(link); 32091da177e4SLinus Torvalds if (len > (unsigned) buflen) 32101da177e4SLinus Torvalds len = buflen; 32111da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32121da177e4SLinus Torvalds len = -EFAULT; 32131da177e4SLinus Torvalds out: 32141da177e4SLinus Torvalds return len; 32151da177e4SLinus Torvalds } 32161da177e4SLinus Torvalds 32171da177e4SLinus Torvalds /* 32181da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32191da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32201da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32211da177e4SLinus Torvalds */ 32221da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32231da177e4SLinus Torvalds { 32241da177e4SLinus Torvalds struct nameidata nd; 3225cc314eefSLinus Torvalds void *cookie; 3226694a1764SMarcin Slusarz int res; 3227cc314eefSLinus Torvalds 32281da177e4SLinus Torvalds nd.depth = 0; 3229cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3230694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3231694a1764SMarcin Slusarz return PTR_ERR(cookie); 3232694a1764SMarcin Slusarz 3233694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32341da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3235cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3236694a1764SMarcin Slusarz return res; 32371da177e4SLinus Torvalds } 32381da177e4SLinus Torvalds 32391da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32401da177e4SLinus Torvalds { 32411da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32421da177e4SLinus Torvalds } 32431da177e4SLinus Torvalds 32441da177e4SLinus Torvalds /* get the link contents into pagecache */ 32451da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32461da177e4SLinus Torvalds { 3247ebd09abbSDuane Griffin char *kaddr; 32481da177e4SLinus Torvalds struct page *page; 32491da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3250090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32511da177e4SLinus Torvalds if (IS_ERR(page)) 32526fe6900eSNick Piggin return (char*)page; 32531da177e4SLinus Torvalds *ppage = page; 3254ebd09abbSDuane Griffin kaddr = kmap(page); 3255ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3256ebd09abbSDuane Griffin return kaddr; 32571da177e4SLinus Torvalds } 32581da177e4SLinus Torvalds 32591da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32601da177e4SLinus Torvalds { 32611da177e4SLinus Torvalds struct page *page = NULL; 32621da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32631da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32641da177e4SLinus Torvalds if (page) { 32651da177e4SLinus Torvalds kunmap(page); 32661da177e4SLinus Torvalds page_cache_release(page); 32671da177e4SLinus Torvalds } 32681da177e4SLinus Torvalds return res; 32691da177e4SLinus Torvalds } 32701da177e4SLinus Torvalds 3271cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 32721da177e4SLinus Torvalds { 3273cc314eefSLinus Torvalds struct page *page = NULL; 32741da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3275cc314eefSLinus Torvalds return page; 32761da177e4SLinus Torvalds } 32771da177e4SLinus Torvalds 3278cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 32791da177e4SLinus Torvalds { 3280cc314eefSLinus Torvalds struct page *page = cookie; 3281cc314eefSLinus Torvalds 3282cc314eefSLinus Torvalds if (page) { 32831da177e4SLinus Torvalds kunmap(page); 32841da177e4SLinus Torvalds page_cache_release(page); 32851da177e4SLinus Torvalds } 32861da177e4SLinus Torvalds } 32871da177e4SLinus Torvalds 328854566b2cSNick Piggin /* 328954566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 329054566b2cSNick Piggin */ 329154566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 32921da177e4SLinus Torvalds { 32931da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 32940adb25d2SKirill Korotaev struct page *page; 3295afddba49SNick Piggin void *fsdata; 3296beb497abSDmitriy Monakhov int err; 32971da177e4SLinus Torvalds char *kaddr; 329854566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 329954566b2cSNick Piggin if (nofs) 330054566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33011da177e4SLinus Torvalds 33027e53cac4SNeilBrown retry: 3303afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 330454566b2cSNick Piggin flags, &page, &fsdata); 33051da177e4SLinus Torvalds if (err) 3306afddba49SNick Piggin goto fail; 3307afddba49SNick Piggin 33081da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33091da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33101da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3311afddba49SNick Piggin 3312afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3313afddba49SNick Piggin page, fsdata); 33141da177e4SLinus Torvalds if (err < 0) 33151da177e4SLinus Torvalds goto fail; 3316afddba49SNick Piggin if (err < len-1) 3317afddba49SNick Piggin goto retry; 3318afddba49SNick Piggin 33191da177e4SLinus Torvalds mark_inode_dirty(inode); 33201da177e4SLinus Torvalds return 0; 33211da177e4SLinus Torvalds fail: 33221da177e4SLinus Torvalds return err; 33231da177e4SLinus Torvalds } 33241da177e4SLinus Torvalds 33250adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33260adb25d2SKirill Korotaev { 33270adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 332854566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33290adb25d2SKirill Korotaev } 33300adb25d2SKirill Korotaev 333192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33321da177e4SLinus Torvalds .readlink = generic_readlink, 33331da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33341da177e4SLinus Torvalds .put_link = page_put_link, 33351da177e4SLinus Torvalds }; 33361da177e4SLinus Torvalds 33372d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3338cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33391da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33401da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33411da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33421da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33431da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33441da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33451da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33461da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33471da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33480adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33491da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33501da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3351c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3352d1811465SAl Viro EXPORT_SYMBOL(kern_path); 335316f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3354f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33551da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33561da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33571da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33581da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33591da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33601da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33611da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33621da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33631da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33641da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33651da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33661da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33671da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 33681da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3369