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 */ 179b74c79e9SNick Piggin static int acl_permission_check(struct inode *inode, int mask, unsigned int flags, 180b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 1815909ccaaSLinus Torvalds { 18226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 1835909ccaaSLinus Torvalds 1845909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 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 { 1925909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 193b74c79e9SNick Piggin int error = check_acl(inode, mask, flags); 1945909ccaaSLinus Torvalds if (error != -EAGAIN) 1955909ccaaSLinus Torvalds return error; 1965909ccaaSLinus Torvalds } 1975909ccaaSLinus Torvalds 1985909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1995909ccaaSLinus Torvalds mode >>= 3; 2005909ccaaSLinus Torvalds } 2015909ccaaSLinus Torvalds 202e795b717SSerge E. Hallyn other_perms: 2035909ccaaSLinus Torvalds /* 2045909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2055909ccaaSLinus Torvalds */ 2065909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 2075909ccaaSLinus Torvalds return 0; 2085909ccaaSLinus Torvalds return -EACCES; 2095909ccaaSLinus Torvalds } 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds /** 2121da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2131da177e4SLinus Torvalds * @inode: inode to check access rights for 2141da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2151da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 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 */ 227b74c79e9SNick Piggin int generic_permission(struct inode *inode, int mask, unsigned int flags, 228b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 2291da177e4SLinus Torvalds { 2305909ccaaSLinus Torvalds int ret; 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds /* 2335909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2341da177e4SLinus Torvalds */ 235b74c79e9SNick Piggin ret = acl_permission_check(inode, mask, flags, check_acl); 2365909ccaaSLinus Torvalds if (ret != -EACCES) 2375909ccaaSLinus Torvalds return ret; 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds /* 2401da177e4SLinus Torvalds * Read/write DACs are always overridable. 2418e833fd2SAl Viro * Executable DACs are overridable for all directories and 2428e833fd2SAl Viro * for non-directories that have least one exec bit set. 2431da177e4SLinus Torvalds */ 244f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 245e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 2461da177e4SLinus Torvalds return 0; 2471da177e4SLinus Torvalds 2481da177e4SLinus Torvalds /* 2491da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2501da177e4SLinus Torvalds */ 2517ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2521da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 253e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 2541da177e4SLinus Torvalds return 0; 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds return -EACCES; 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds 259cb23beb5SChristoph Hellwig /** 260cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 261cb23beb5SChristoph Hellwig * @inode: inode to check permission on 262cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 263cb23beb5SChristoph Hellwig * 264cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 265cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 266cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 267cb23beb5SChristoph Hellwig * are used for other things. 268cb23beb5SChristoph Hellwig */ 269f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2701da177e4SLinus Torvalds { 271e6305c43SAl Viro int retval; 2721da177e4SLinus Torvalds 2731da177e4SLinus Torvalds if (mask & MAY_WRITE) { 27422590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2751da177e4SLinus Torvalds 2761da177e4SLinus Torvalds /* 2771da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2781da177e4SLinus Torvalds */ 2791da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2801da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2811da177e4SLinus Torvalds return -EROFS; 2821da177e4SLinus Torvalds 2831da177e4SLinus Torvalds /* 2841da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2851da177e4SLinus Torvalds */ 2861da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2871da177e4SLinus Torvalds return -EACCES; 2881da177e4SLinus Torvalds } 2891da177e4SLinus Torvalds 290acfa4380SAl Viro if (inode->i_op->permission) 291b74c79e9SNick Piggin retval = inode->i_op->permission(inode, mask, 0); 292f696a365SMiklos Szeredi else 293b74c79e9SNick Piggin retval = generic_permission(inode, mask, 0, 294b74c79e9SNick Piggin inode->i_op->check_acl); 295f696a365SMiklos Szeredi 2961da177e4SLinus Torvalds if (retval) 2971da177e4SLinus Torvalds return retval; 2981da177e4SLinus Torvalds 29908ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 30008ce5f16SSerge E. Hallyn if (retval) 30108ce5f16SSerge E. Hallyn return retval; 30208ce5f16SSerge E. Hallyn 303d09ca739SEric Paris return security_inode_permission(inode, mask); 3041da177e4SLinus Torvalds } 3051da177e4SLinus Torvalds 306e4543eddSChristoph Hellwig /** 3078c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 3088c744fb8SChristoph Hellwig * @file: file to check access rights for 3098c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3108c744fb8SChristoph Hellwig * 3118c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3128c744fb8SChristoph Hellwig * file. 3138c744fb8SChristoph Hellwig * 3148c744fb8SChristoph Hellwig * Note: 3158c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 316cb23beb5SChristoph Hellwig * be done using inode_permission(). 3178c744fb8SChristoph Hellwig */ 3188c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3198c744fb8SChristoph Hellwig { 320f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3218c744fb8SChristoph Hellwig } 3228c744fb8SChristoph Hellwig 3231da177e4SLinus Torvalds /* 3241da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3251da177e4SLinus Torvalds * put_write_access() releases this write permission. 3261da177e4SLinus Torvalds * This is used for regular files. 3271da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3281da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3291da177e4SLinus Torvalds * can have the following values: 3301da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3311da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3321da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3331da177e4SLinus Torvalds * 3341da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3351da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3361da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3371da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3381da177e4SLinus Torvalds * the inode->i_lock spinlock. 3391da177e4SLinus Torvalds */ 3401da177e4SLinus Torvalds 3411da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3421da177e4SLinus Torvalds { 3431da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3441da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3451da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3461da177e4SLinus Torvalds return -ETXTBSY; 3471da177e4SLinus Torvalds } 3481da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3491da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3501da177e4SLinus Torvalds 3511da177e4SLinus Torvalds return 0; 3521da177e4SLinus Torvalds } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds int deny_write_access(struct file * file) 3551da177e4SLinus Torvalds { 3560f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3591da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3601da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3611da177e4SLinus Torvalds return -ETXTBSY; 3621da177e4SLinus Torvalds } 3631da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3641da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return 0; 3671da177e4SLinus Torvalds } 3681da177e4SLinus Torvalds 3691d957f9bSJan Blunck /** 3705dd784d0SJan Blunck * path_get - get a reference to a path 3715dd784d0SJan Blunck * @path: path to get the reference to 3725dd784d0SJan Blunck * 3735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3745dd784d0SJan Blunck */ 3755dd784d0SJan Blunck void path_get(struct path *path) 3765dd784d0SJan Blunck { 3775dd784d0SJan Blunck mntget(path->mnt); 3785dd784d0SJan Blunck dget(path->dentry); 3795dd784d0SJan Blunck } 3805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3815dd784d0SJan Blunck 3825dd784d0SJan Blunck /** 3831d957f9bSJan Blunck * path_put - put a reference to a path 3841d957f9bSJan Blunck * @path: path to put the reference to 3851d957f9bSJan Blunck * 3861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3871d957f9bSJan Blunck */ 3881d957f9bSJan Blunck void path_put(struct path *path) 3891da177e4SLinus Torvalds { 3901d957f9bSJan Blunck dput(path->dentry); 3911d957f9bSJan Blunck mntput(path->mnt); 3921da177e4SLinus Torvalds } 3931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3941da177e4SLinus Torvalds 39519660af7SAl Viro /* 39631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 39719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 39819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 39919660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 40019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 40119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 40219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 40319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 40431e6b01fSNick Piggin */ 40531e6b01fSNick Piggin 40631e6b01fSNick Piggin /** 40719660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 40819660af7SAl Viro * @nd: nameidata pathwalk data 40919660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 41039191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 41131e6b01fSNick Piggin * 41219660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 41319660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 41419660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 41531e6b01fSNick Piggin */ 41619660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 41731e6b01fSNick Piggin { 41831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 41931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4205b6ca027SAl Viro int want_root = 0; 42131e6b01fSNick Piggin 42231e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4235b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4245b6ca027SAl Viro want_root = 1; 42531e6b01fSNick Piggin spin_lock(&fs->lock); 42631e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 42731e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 42831e6b01fSNick Piggin goto err_root; 42931e6b01fSNick Piggin } 43031e6b01fSNick Piggin spin_lock(&parent->d_lock); 43119660af7SAl Viro if (!dentry) { 43219660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 43319660af7SAl Viro goto err_parent; 43419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 43519660af7SAl Viro } else { 43694c0d4ecSAl Viro if (dentry->d_parent != parent) 43794c0d4ecSAl Viro goto err_parent; 43831e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 43931e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 44019660af7SAl Viro goto err_child; 44131e6b01fSNick Piggin /* 44219660af7SAl Viro * If the sequence check on the child dentry passed, then 44319660af7SAl Viro * the child has not been removed from its parent. This 44419660af7SAl Viro * means the parent dentry must be valid and able to take 44519660af7SAl Viro * a reference at this point. 44631e6b01fSNick Piggin */ 44731e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 44831e6b01fSNick Piggin BUG_ON(!parent->d_count); 44931e6b01fSNick Piggin parent->d_count++; 45031e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 45119660af7SAl Viro } 45231e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4535b6ca027SAl Viro if (want_root) { 45431e6b01fSNick Piggin path_get(&nd->root); 45531e6b01fSNick Piggin spin_unlock(&fs->lock); 45631e6b01fSNick Piggin } 45731e6b01fSNick Piggin mntget(nd->path.mnt); 45831e6b01fSNick Piggin 45931e6b01fSNick Piggin rcu_read_unlock(); 46031e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 46131e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 46231e6b01fSNick Piggin return 0; 46319660af7SAl Viro 46419660af7SAl Viro err_child: 46531e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 46619660af7SAl Viro err_parent: 46731e6b01fSNick Piggin spin_unlock(&parent->d_lock); 46831e6b01fSNick Piggin err_root: 4695b6ca027SAl Viro if (want_root) 47031e6b01fSNick Piggin spin_unlock(&fs->lock); 47131e6b01fSNick Piggin return -ECHILD; 47231e6b01fSNick Piggin } 47331e6b01fSNick Piggin 47431e6b01fSNick Piggin /** 475834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 476834f2a4aSTrond Myklebust * @nd: pointer to nameidata 477834f2a4aSTrond Myklebust */ 478834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 479834f2a4aSTrond Myklebust { 4802dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4812dab5974SLinus Torvalds 4822dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4832dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4842dab5974SLinus Torvalds put_filp(file); 485834f2a4aSTrond Myklebust else 4862dab5974SLinus Torvalds fput(file); 4872dab5974SLinus Torvalds } 488834f2a4aSTrond Myklebust } 489834f2a4aSTrond Myklebust 490f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 49134286d66SNick Piggin { 492f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 49334286d66SNick Piggin } 49434286d66SNick Piggin 495f5e1c1c1SAl Viro static struct dentry * 496bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 497bcdc5e01SIan Kent { 498f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 499bcdc5e01SIan Kent if (unlikely(status <= 0)) { 500bcdc5e01SIan Kent /* 501bcdc5e01SIan Kent * The dentry failed validation. 502bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 503bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 504bcdc5e01SIan Kent * to return a fail status. 505bcdc5e01SIan Kent */ 50634286d66SNick Piggin if (status < 0) { 50734286d66SNick Piggin dput(dentry); 50834286d66SNick Piggin dentry = ERR_PTR(status); 509f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 510bcdc5e01SIan Kent dput(dentry); 511bcdc5e01SIan Kent dentry = NULL; 512bcdc5e01SIan Kent } 513bcdc5e01SIan Kent } 514f5e1c1c1SAl Viro return dentry; 515f5e1c1c1SAl Viro } 516f5e1c1c1SAl Viro 5179f1fafeeSAl Viro /** 5189f1fafeeSAl Viro * complete_walk - successful completion of path walk 5199f1fafeeSAl Viro * @nd: pointer nameidata 52039159de2SJeff Layton * 5219f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5229f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5239f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5249f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5259f1fafeeSAl Viro * need to drop nd->path. 52639159de2SJeff Layton */ 5279f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 52839159de2SJeff Layton { 52916c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 53039159de2SJeff Layton int status; 53139159de2SJeff Layton 5329f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5339f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5349f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5359f1fafeeSAl Viro nd->root.mnt = NULL; 5369f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5379f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5389f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5399f1fafeeSAl Viro rcu_read_unlock(); 5409f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5419f1fafeeSAl Viro return -ECHILD; 5429f1fafeeSAl Viro } 5439f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5449f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5459f1fafeeSAl Viro mntget(nd->path.mnt); 5469f1fafeeSAl Viro rcu_read_unlock(); 5479f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5489f1fafeeSAl Viro } 5499f1fafeeSAl Viro 55016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 55139159de2SJeff Layton return 0; 55239159de2SJeff Layton 55316c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 55416c2cd71SAl Viro return 0; 55516c2cd71SAl Viro 55616c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 55716c2cd71SAl Viro return 0; 55816c2cd71SAl Viro 55916c2cd71SAl Viro /* Note: we do not d_invalidate() */ 56034286d66SNick Piggin status = d_revalidate(dentry, nd); 56139159de2SJeff Layton if (status > 0) 56239159de2SJeff Layton return 0; 56339159de2SJeff Layton 56416c2cd71SAl Viro if (!status) 56539159de2SJeff Layton status = -ESTALE; 56616c2cd71SAl Viro 5679f1fafeeSAl Viro path_put(&nd->path); 56839159de2SJeff Layton return status; 56939159de2SJeff Layton } 57039159de2SJeff Layton 57139159de2SJeff Layton /* 572b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 573b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 574b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 5751da177e4SLinus Torvalds * 5761da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 577b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 5781da177e4SLinus Torvalds * complete permission check. 5791da177e4SLinus Torvalds */ 580b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 5811da177e4SLinus Torvalds { 5825909ccaaSLinus Torvalds int ret; 583e795b717SSerge E. Hallyn struct user_namespace *ns = inode_userns(inode); 5841da177e4SLinus Torvalds 585cb9179eaSLinus Torvalds if (inode->i_op->permission) { 586b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 587b74c79e9SNick Piggin } else { 588b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 589b74c79e9SNick Piggin inode->i_op->check_acl); 590cb9179eaSLinus Torvalds } 591b74c79e9SNick Piggin if (likely(!ret)) 5921da177e4SLinus Torvalds goto ok; 593b74c79e9SNick Piggin if (ret == -ECHILD) 59431e6b01fSNick Piggin return ret; 5951da177e4SLinus Torvalds 596e795b717SSerge E. Hallyn if (ns_capable(ns, CAP_DAC_OVERRIDE) || 597e795b717SSerge E. Hallyn ns_capable(ns, CAP_DAC_READ_SEARCH)) 5981da177e4SLinus Torvalds goto ok; 5991da177e4SLinus Torvalds 6005909ccaaSLinus Torvalds return ret; 6011da177e4SLinus Torvalds ok: 602b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 6031da177e4SLinus Torvalds } 6041da177e4SLinus Torvalds 6052a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6062a737871SAl Viro { 607f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 608f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6092a737871SAl Viro } 6102a737871SAl Viro 6116de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6126de88d72SAl Viro 61331e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 61431e6b01fSNick Piggin { 61531e6b01fSNick Piggin if (!nd->root.mnt) { 61631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 617c28cc364SNick Piggin unsigned seq; 618c28cc364SNick Piggin 619c28cc364SNick Piggin do { 620c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 62131e6b01fSNick Piggin nd->root = fs->root; 622c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 623c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 62431e6b01fSNick Piggin } 62531e6b01fSNick Piggin } 62631e6b01fSNick Piggin 627f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6281da177e4SLinus Torvalds { 62931e6b01fSNick Piggin int ret; 63031e6b01fSNick Piggin 6311da177e4SLinus Torvalds if (IS_ERR(link)) 6321da177e4SLinus Torvalds goto fail; 6331da177e4SLinus Torvalds 6341da177e4SLinus Torvalds if (*link == '/') { 6352a737871SAl Viro set_root(nd); 6361d957f9bSJan Blunck path_put(&nd->path); 6372a737871SAl Viro nd->path = nd->root; 6382a737871SAl Viro path_get(&nd->root); 63916c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6401da177e4SLinus Torvalds } 64131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 642b4091d5fSChristoph Hellwig 64331e6b01fSNick Piggin ret = link_path_walk(link, nd); 64431e6b01fSNick Piggin return ret; 6451da177e4SLinus Torvalds fail: 6461d957f9bSJan Blunck path_put(&nd->path); 6471da177e4SLinus Torvalds return PTR_ERR(link); 6481da177e4SLinus Torvalds } 6491da177e4SLinus Torvalds 6501d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 651051d3812SIan Kent { 652051d3812SIan Kent dput(path->dentry); 6534ac91378SJan Blunck if (path->mnt != nd->path.mnt) 654051d3812SIan Kent mntput(path->mnt); 655051d3812SIan Kent } 656051d3812SIan Kent 6577b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6587b9337aaSNick Piggin struct nameidata *nd) 659051d3812SIan Kent { 66031e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6614ac91378SJan Blunck dput(nd->path.dentry); 66231e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6634ac91378SJan Blunck mntput(nd->path.mnt); 6649a229683SHuang Shijie } 66531e6b01fSNick Piggin nd->path.mnt = path->mnt; 6664ac91378SJan Blunck nd->path.dentry = path->dentry; 667051d3812SIan Kent } 668051d3812SIan Kent 669574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 670574197e0SAl Viro { 671574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 672574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 673574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 674574197e0SAl Viro path_put(link); 675574197e0SAl Viro } 676574197e0SAl Viro 677def4af30SAl Viro static __always_inline int 678574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6791da177e4SLinus Torvalds { 6801da177e4SLinus Torvalds int error; 6817b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6821da177e4SLinus Torvalds 683844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 684844a3917SAl Viro 6850e794589SAl Viro if (link->mnt == nd->path.mnt) 6860e794589SAl Viro mntget(link->mnt); 6870e794589SAl Viro 688574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 689574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 690574197e0SAl Viro path_put(&nd->path); 691574197e0SAl Viro return -ELOOP; 692574197e0SAl Viro } 693574197e0SAl Viro cond_resched(); 694574197e0SAl Viro current->total_link_count++; 695574197e0SAl Viro 6967b9337aaSNick Piggin touch_atime(link->mnt, dentry); 6971da177e4SLinus Torvalds nd_set_link(nd, NULL); 698cd4e91d3SAl Viro 69936f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 70036f3b4f6SAl Viro if (error) { 70136f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 70236f3b4f6SAl Viro path_put(&nd->path); 70336f3b4f6SAl Viro return error; 70436f3b4f6SAl Viro } 70536f3b4f6SAl Viro 70686acdca1SAl Viro nd->last_type = LAST_BIND; 707def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 708def4af30SAl Viro error = PTR_ERR(*p); 709def4af30SAl Viro if (!IS_ERR(*p)) { 7101da177e4SLinus Torvalds char *s = nd_get_link(nd); 711cc314eefSLinus Torvalds error = 0; 7121da177e4SLinus Torvalds if (s) 7131da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 714bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 71516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 716b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 717b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 718bcda7652SAl Viro /* stepped on a _really_ weird one */ 719bcda7652SAl Viro path_put(&nd->path); 720bcda7652SAl Viro error = -ELOOP; 721bcda7652SAl Viro } 722bcda7652SAl Viro } 7231da177e4SLinus Torvalds } 7241da177e4SLinus Torvalds return error; 7251da177e4SLinus Torvalds } 7261da177e4SLinus Torvalds 72731e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 72831e6b01fSNick Piggin { 72931e6b01fSNick Piggin struct vfsmount *parent; 73031e6b01fSNick Piggin struct dentry *mountpoint; 73131e6b01fSNick Piggin 73231e6b01fSNick Piggin parent = path->mnt->mnt_parent; 73331e6b01fSNick Piggin if (parent == path->mnt) 73431e6b01fSNick Piggin return 0; 73531e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 73631e6b01fSNick Piggin path->dentry = mountpoint; 73731e6b01fSNick Piggin path->mnt = parent; 73831e6b01fSNick Piggin return 1; 73931e6b01fSNick Piggin } 74031e6b01fSNick Piggin 741bab77ebfSAl Viro int follow_up(struct path *path) 7421da177e4SLinus Torvalds { 7431da177e4SLinus Torvalds struct vfsmount *parent; 7441da177e4SLinus Torvalds struct dentry *mountpoint; 74599b7db7bSNick Piggin 74699b7db7bSNick Piggin br_read_lock(vfsmount_lock); 747bab77ebfSAl Viro parent = path->mnt->mnt_parent; 748bab77ebfSAl Viro if (parent == path->mnt) { 74999b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 7501da177e4SLinus Torvalds return 0; 7511da177e4SLinus Torvalds } 7521da177e4SLinus Torvalds mntget(parent); 753bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 75499b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 755bab77ebfSAl Viro dput(path->dentry); 756bab77ebfSAl Viro path->dentry = mountpoint; 757bab77ebfSAl Viro mntput(path->mnt); 758bab77ebfSAl Viro path->mnt = parent; 7591da177e4SLinus Torvalds return 1; 7601da177e4SLinus Torvalds } 7611da177e4SLinus Torvalds 762b5c84bf6SNick Piggin /* 7639875cf80SDavid Howells * Perform an automount 7649875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7659875cf80SDavid Howells * were called with. 7661da177e4SLinus Torvalds */ 7679875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7689875cf80SDavid Howells bool *need_mntput) 76931e6b01fSNick Piggin { 7709875cf80SDavid Howells struct vfsmount *mnt; 771ea5b778aSDavid Howells int err; 7729875cf80SDavid Howells 7739875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7749875cf80SDavid Howells return -EREMOTE; 7759875cf80SDavid Howells 7766f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 7776f45b656SDavid Howells * and this is the terminal part of the path. 7786f45b656SDavid Howells */ 7796f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 7806f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 7816f45b656SDavid Howells 7829875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 7839875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 7849875cf80SDavid Howells * or wants to open the mounted directory. 7859875cf80SDavid Howells * 7869875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 7879875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 7889875cf80SDavid Howells * appended a '/' to the name. 7899875cf80SDavid Howells */ 7909875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 7919875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 7929875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 7939875cf80SDavid Howells return -EISDIR; 7949875cf80SDavid Howells 7959875cf80SDavid Howells current->total_link_count++; 7969875cf80SDavid Howells if (current->total_link_count >= 40) 7979875cf80SDavid Howells return -ELOOP; 7989875cf80SDavid Howells 7999875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8009875cf80SDavid Howells if (IS_ERR(mnt)) { 8019875cf80SDavid Howells /* 8029875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8039875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 8049875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 8059875cf80SDavid Howells * 8069875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 8079875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 8089875cf80SDavid Howells * the path is inaccessible and we should say so. 8099875cf80SDavid Howells */ 8109875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 8119875cf80SDavid Howells return -EREMOTE; 8129875cf80SDavid Howells return PTR_ERR(mnt); 81331e6b01fSNick Piggin } 814ea5b778aSDavid Howells 8159875cf80SDavid Howells if (!mnt) /* mount collision */ 8169875cf80SDavid Howells return 0; 8179875cf80SDavid Howells 8188aef1884SAl Viro if (!*need_mntput) { 8198aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 8208aef1884SAl Viro mntget(path->mnt); 8218aef1884SAl Viro *need_mntput = true; 8228aef1884SAl Viro } 82319a167afSAl Viro err = finish_automount(mnt, path); 824ea5b778aSDavid Howells 825ea5b778aSDavid Howells switch (err) { 826ea5b778aSDavid Howells case -EBUSY: 827ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 82819a167afSAl Viro return 0; 829ea5b778aSDavid Howells case 0: 8308aef1884SAl Viro path_put(path); 8319875cf80SDavid Howells path->mnt = mnt; 8329875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 8339875cf80SDavid Howells return 0; 83419a167afSAl Viro default: 83519a167afSAl Viro return err; 8369875cf80SDavid Howells } 83719a167afSAl Viro 838ea5b778aSDavid Howells } 8399875cf80SDavid Howells 8409875cf80SDavid Howells /* 8419875cf80SDavid Howells * Handle a dentry that is managed in some way. 842cc53ce53SDavid Howells * - Flagged for transit management (autofs) 8439875cf80SDavid Howells * - Flagged as mountpoint 8449875cf80SDavid Howells * - Flagged as automount point 8459875cf80SDavid Howells * 8469875cf80SDavid Howells * This may only be called in refwalk mode. 8479875cf80SDavid Howells * 8489875cf80SDavid Howells * Serialization is taken care of in namespace.c 8499875cf80SDavid Howells */ 8509875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 8519875cf80SDavid Howells { 8528aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 8539875cf80SDavid Howells unsigned managed; 8549875cf80SDavid Howells bool need_mntput = false; 8558aef1884SAl Viro int ret = 0; 8569875cf80SDavid Howells 8579875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8589875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8599875cf80SDavid Howells * the components of that value change under us */ 8609875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8619875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8629875cf80SDavid Howells unlikely(managed != 0)) { 863cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 864cc53ce53SDavid Howells * being held. */ 865cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 866cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 867cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8681aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 869cc53ce53SDavid Howells if (ret < 0) 8708aef1884SAl Viro break; 871cc53ce53SDavid Howells } 872cc53ce53SDavid Howells 8739875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8749875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8759875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8769875cf80SDavid Howells if (mounted) { 8779875cf80SDavid Howells dput(path->dentry); 8789875cf80SDavid Howells if (need_mntput) 879463ffb2eSAl Viro mntput(path->mnt); 880463ffb2eSAl Viro path->mnt = mounted; 881463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8829875cf80SDavid Howells need_mntput = true; 8839875cf80SDavid Howells continue; 884463ffb2eSAl Viro } 885463ffb2eSAl Viro 8869875cf80SDavid Howells /* Something is mounted on this dentry in another 8879875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8889875cf80SDavid Howells * namespace got unmounted before we managed to get the 8899875cf80SDavid Howells * vfsmount_lock */ 8901da177e4SLinus Torvalds } 8919875cf80SDavid Howells 8929875cf80SDavid Howells /* Handle an automount point */ 8939875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8949875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8959875cf80SDavid Howells if (ret < 0) 8968aef1884SAl Viro break; 8979875cf80SDavid Howells continue; 8989875cf80SDavid Howells } 8999875cf80SDavid Howells 9009875cf80SDavid Howells /* We didn't change the current path point */ 9019875cf80SDavid Howells break; 9029875cf80SDavid Howells } 9038aef1884SAl Viro 9048aef1884SAl Viro if (need_mntput && path->mnt == mnt) 9058aef1884SAl Viro mntput(path->mnt); 9068aef1884SAl Viro if (ret == -EISDIR) 9078aef1884SAl Viro ret = 0; 9088aef1884SAl Viro return ret; 9091da177e4SLinus Torvalds } 9101da177e4SLinus Torvalds 911cc53ce53SDavid Howells int follow_down_one(struct path *path) 9121da177e4SLinus Torvalds { 9131da177e4SLinus Torvalds struct vfsmount *mounted; 9141da177e4SLinus Torvalds 9151c755af4SAl Viro mounted = lookup_mnt(path); 9161da177e4SLinus Torvalds if (mounted) { 9179393bd07SAl Viro dput(path->dentry); 9189393bd07SAl Viro mntput(path->mnt); 9199393bd07SAl Viro path->mnt = mounted; 9209393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9211da177e4SLinus Torvalds return 1; 9221da177e4SLinus Torvalds } 9231da177e4SLinus Torvalds return 0; 9241da177e4SLinus Torvalds } 9251da177e4SLinus Torvalds 92662a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 92762a7375eSIan Kent { 92862a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 92962a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 93062a7375eSIan Kent } 93162a7375eSIan Kent 9329875cf80SDavid Howells /* 933287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 934287548e4SAl Viro * we meet a managed dentry that would need blocking. 9359875cf80SDavid Howells */ 9369875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 937287548e4SAl Viro struct inode **inode) 9389875cf80SDavid Howells { 93962a7375eSIan Kent for (;;) { 9409875cf80SDavid Howells struct vfsmount *mounted; 94162a7375eSIan Kent /* 94262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 94362a7375eSIan Kent * that wants to block transit. 94462a7375eSIan Kent */ 945287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 946ab90911fSDavid Howells return false; 94762a7375eSIan Kent 94862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 94962a7375eSIan Kent break; 95062a7375eSIan Kent 9519875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9529875cf80SDavid Howells if (!mounted) 9539875cf80SDavid Howells break; 9549875cf80SDavid Howells path->mnt = mounted; 9559875cf80SDavid Howells path->dentry = mounted->mnt_root; 9569875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 95759430262SLinus Torvalds /* 95859430262SLinus Torvalds * Update the inode too. We don't need to re-check the 95959430262SLinus Torvalds * dentry sequence number here after this d_inode read, 96059430262SLinus Torvalds * because a mount-point is always pinned. 96159430262SLinus Torvalds */ 96259430262SLinus Torvalds *inode = path->dentry->d_inode; 9639875cf80SDavid Howells } 9649875cf80SDavid Howells return true; 9659875cf80SDavid Howells } 9669875cf80SDavid Howells 967dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 968287548e4SAl Viro { 969dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 970287548e4SAl Viro struct vfsmount *mounted; 971dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 972287548e4SAl Viro if (!mounted) 973287548e4SAl Viro break; 974dea39376SAl Viro nd->path.mnt = mounted; 975dea39376SAl Viro nd->path.dentry = mounted->mnt_root; 976dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 977287548e4SAl Viro } 978287548e4SAl Viro } 979287548e4SAl Viro 98031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 98131e6b01fSNick Piggin { 98231e6b01fSNick Piggin set_root_rcu(nd); 98331e6b01fSNick Piggin 98431e6b01fSNick Piggin while (1) { 98531e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 98631e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 98731e6b01fSNick Piggin break; 98831e6b01fSNick Piggin } 98931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 99031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 99131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 99231e6b01fSNick Piggin unsigned seq; 99331e6b01fSNick Piggin 99431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 99531e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 996ef7562d5SAl Viro goto failed; 99731e6b01fSNick Piggin nd->path.dentry = parent; 99831e6b01fSNick Piggin nd->seq = seq; 99931e6b01fSNick Piggin break; 100031e6b01fSNick Piggin } 100131e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 100231e6b01fSNick Piggin break; 100331e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 100431e6b01fSNick Piggin } 1005dea39376SAl Viro follow_mount_rcu(nd); 1006dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 100731e6b01fSNick Piggin return 0; 1008ef7562d5SAl Viro 1009ef7562d5SAl Viro failed: 1010ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 10115b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1012ef7562d5SAl Viro nd->root.mnt = NULL; 1013ef7562d5SAl Viro rcu_read_unlock(); 1014ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 1015ef7562d5SAl Viro return -ECHILD; 101631e6b01fSNick Piggin } 101731e6b01fSNick Piggin 10189875cf80SDavid Howells /* 1019cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1020cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1021cc53ce53SDavid Howells * caller is permitted to proceed or not. 1022cc53ce53SDavid Howells */ 10237cc90cc3SAl Viro int follow_down(struct path *path) 1024cc53ce53SDavid Howells { 1025cc53ce53SDavid Howells unsigned managed; 1026cc53ce53SDavid Howells int ret; 1027cc53ce53SDavid Howells 1028cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1029cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1030cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1031cc53ce53SDavid Howells * being held. 1032cc53ce53SDavid Howells * 1033cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1034cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1035cc53ce53SDavid Howells * other than its daemon the right to mount on its 1036cc53ce53SDavid Howells * superstructure. 1037cc53ce53SDavid Howells * 1038cc53ce53SDavid Howells * The filesystem may sleep at this point. 1039cc53ce53SDavid Howells */ 1040cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1041cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1042cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1043ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 10441aed3e42SAl Viro path->dentry, false); 1045cc53ce53SDavid Howells if (ret < 0) 1046cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1047cc53ce53SDavid Howells } 1048cc53ce53SDavid Howells 1049cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1050cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1051cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1052cc53ce53SDavid Howells if (!mounted) 1053cc53ce53SDavid Howells break; 1054cc53ce53SDavid Howells dput(path->dentry); 1055cc53ce53SDavid Howells mntput(path->mnt); 1056cc53ce53SDavid Howells path->mnt = mounted; 1057cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1058cc53ce53SDavid Howells continue; 1059cc53ce53SDavid Howells } 1060cc53ce53SDavid Howells 1061cc53ce53SDavid Howells /* Don't handle automount points here */ 1062cc53ce53SDavid Howells break; 1063cc53ce53SDavid Howells } 1064cc53ce53SDavid Howells return 0; 1065cc53ce53SDavid Howells } 1066cc53ce53SDavid Howells 1067cc53ce53SDavid Howells /* 10689875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10699875cf80SDavid Howells */ 10709875cf80SDavid Howells static void follow_mount(struct path *path) 10719875cf80SDavid Howells { 10729875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10739875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10749875cf80SDavid Howells if (!mounted) 10759875cf80SDavid Howells break; 10769875cf80SDavid Howells dput(path->dentry); 10779875cf80SDavid Howells mntput(path->mnt); 10789875cf80SDavid Howells path->mnt = mounted; 10799875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10809875cf80SDavid Howells } 10819875cf80SDavid Howells } 10829875cf80SDavid Howells 108331e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10841da177e4SLinus Torvalds { 10852a737871SAl Viro set_root(nd); 1086e518ddb7SAndreas Mohr 10871da177e4SLinus Torvalds while(1) { 10884ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10891da177e4SLinus Torvalds 10902a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10912a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10921da177e4SLinus Torvalds break; 10931da177e4SLinus Torvalds } 10944ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10953088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10963088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10971da177e4SLinus Torvalds dput(old); 10981da177e4SLinus Torvalds break; 10991da177e4SLinus Torvalds } 11003088dd70SAl Viro if (!follow_up(&nd->path)) 11011da177e4SLinus Torvalds break; 11021da177e4SLinus Torvalds } 110379ed0226SAl Viro follow_mount(&nd->path); 110431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds 11071da177e4SLinus Torvalds /* 1108baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1109baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1110baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1111baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1112baa03890SNick Piggin */ 1113baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1114baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1115baa03890SNick Piggin { 1116baa03890SNick Piggin struct inode *inode = parent->d_inode; 1117baa03890SNick Piggin struct dentry *dentry; 1118baa03890SNick Piggin struct dentry *old; 1119baa03890SNick Piggin 1120baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1121baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1122baa03890SNick Piggin return ERR_PTR(-ENOENT); 1123baa03890SNick Piggin 1124baa03890SNick Piggin dentry = d_alloc(parent, name); 1125baa03890SNick Piggin if (unlikely(!dentry)) 1126baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1127baa03890SNick Piggin 1128baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1129baa03890SNick Piggin if (unlikely(old)) { 1130baa03890SNick Piggin dput(dentry); 1131baa03890SNick Piggin dentry = old; 1132baa03890SNick Piggin } 1133baa03890SNick Piggin return dentry; 1134baa03890SNick Piggin } 1135baa03890SNick Piggin 1136baa03890SNick Piggin /* 113744396f4bSJosef Bacik * We already have a dentry, but require a lookup to be performed on the parent 113844396f4bSJosef Bacik * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. 113944396f4bSJosef Bacik * parent->d_inode->i_mutex must be held. d_lookup must have verified that no 114044396f4bSJosef Bacik * child exists while under i_mutex. 114144396f4bSJosef Bacik */ 114244396f4bSJosef Bacik static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, 114344396f4bSJosef Bacik struct nameidata *nd) 114444396f4bSJosef Bacik { 114544396f4bSJosef Bacik struct inode *inode = parent->d_inode; 114644396f4bSJosef Bacik struct dentry *old; 114744396f4bSJosef Bacik 114844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 114944396f4bSJosef Bacik if (unlikely(IS_DEADDIR(inode))) 115044396f4bSJosef Bacik return ERR_PTR(-ENOENT); 115144396f4bSJosef Bacik 115244396f4bSJosef Bacik old = inode->i_op->lookup(inode, dentry, nd); 115344396f4bSJosef Bacik if (unlikely(old)) { 115444396f4bSJosef Bacik dput(dentry); 115544396f4bSJosef Bacik dentry = old; 115644396f4bSJosef Bacik } 115744396f4bSJosef Bacik return dentry; 115844396f4bSJosef Bacik } 115944396f4bSJosef Bacik 116044396f4bSJosef Bacik /* 11611da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11621da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11631da177e4SLinus Torvalds * It _is_ time-critical. 11641da177e4SLinus Torvalds */ 11651da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 116631e6b01fSNick Piggin struct path *path, struct inode **inode) 11671da177e4SLinus Torvalds { 11684ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 116931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11705a18fff2SAl Viro int need_reval = 1; 11715a18fff2SAl Viro int status = 1; 11729875cf80SDavid Howells int err; 11739875cf80SDavid Howells 11743cac260aSAl Viro /* 1175b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1176b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1177b04f784eSNick Piggin * do the non-racy lookup, below. 1178b04f784eSNick Piggin */ 117931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 118031e6b01fSNick Piggin unsigned seq; 118131e6b01fSNick Piggin *inode = nd->inode; 118231e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11835a18fff2SAl Viro if (!dentry) 11845a18fff2SAl Viro goto unlazy; 11855a18fff2SAl Viro 118631e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 118731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 118831e6b01fSNick Piggin return -ECHILD; 118931e6b01fSNick Piggin nd->seq = seq; 11905a18fff2SAl Viro 119124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11925a18fff2SAl Viro status = d_revalidate(dentry, nd); 11935a18fff2SAl Viro if (unlikely(status <= 0)) { 11945a18fff2SAl Viro if (status != -ECHILD) 11955a18fff2SAl Viro need_reval = 0; 11965a18fff2SAl Viro goto unlazy; 11975a18fff2SAl Viro } 119824643087SAl Viro } 119944396f4bSJosef Bacik if (unlikely(d_need_lookup(dentry))) 120044396f4bSJosef Bacik goto unlazy; 120131e6b01fSNick Piggin path->mnt = mnt; 120231e6b01fSNick Piggin path->dentry = dentry; 1203d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1204d6e9bd25SAl Viro goto unlazy; 1205d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1206d6e9bd25SAl Viro goto unlazy; 12079875cf80SDavid Howells return 0; 12085a18fff2SAl Viro unlazy: 120919660af7SAl Viro if (unlazy_walk(nd, dentry)) 12105a18fff2SAl Viro return -ECHILD; 12115a18fff2SAl Viro } else { 121231e6b01fSNick Piggin dentry = __d_lookup(parent, name); 121324643087SAl Viro } 12145a18fff2SAl Viro 121544396f4bSJosef Bacik if (dentry && unlikely(d_need_lookup(dentry))) { 121644396f4bSJosef Bacik dput(dentry); 121744396f4bSJosef Bacik dentry = NULL; 121844396f4bSJosef Bacik } 12195a18fff2SAl Viro retry: 12205a18fff2SAl Viro if (unlikely(!dentry)) { 12215a18fff2SAl Viro struct inode *dir = parent->d_inode; 12225a18fff2SAl Viro BUG_ON(nd->inode != dir); 12235a18fff2SAl Viro 12245a18fff2SAl Viro mutex_lock(&dir->i_mutex); 12255a18fff2SAl Viro dentry = d_lookup(parent, name); 12265a18fff2SAl Viro if (likely(!dentry)) { 12275a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 12285a18fff2SAl Viro if (IS_ERR(dentry)) { 12295a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12305a18fff2SAl Viro return PTR_ERR(dentry); 12315a18fff2SAl Viro } 12325a18fff2SAl Viro /* known good */ 12335a18fff2SAl Viro need_reval = 0; 12345a18fff2SAl Viro status = 1; 123544396f4bSJosef Bacik } else if (unlikely(d_need_lookup(dentry))) { 123644396f4bSJosef Bacik dentry = d_inode_lookup(parent, dentry, nd); 123744396f4bSJosef Bacik if (IS_ERR(dentry)) { 123844396f4bSJosef Bacik mutex_unlock(&dir->i_mutex); 123944396f4bSJosef Bacik return PTR_ERR(dentry); 124044396f4bSJosef Bacik } 124144396f4bSJosef Bacik /* known good */ 124244396f4bSJosef Bacik need_reval = 0; 124344396f4bSJosef Bacik status = 1; 12445a18fff2SAl Viro } 12455a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12465a18fff2SAl Viro } 12475a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12485a18fff2SAl Viro status = d_revalidate(dentry, nd); 12495a18fff2SAl Viro if (unlikely(status <= 0)) { 12505a18fff2SAl Viro if (status < 0) { 12515a18fff2SAl Viro dput(dentry); 12525a18fff2SAl Viro return status; 12535a18fff2SAl Viro } 12545a18fff2SAl Viro if (!d_invalidate(dentry)) { 12555a18fff2SAl Viro dput(dentry); 12565a18fff2SAl Viro dentry = NULL; 12575a18fff2SAl Viro need_reval = 1; 12585a18fff2SAl Viro goto retry; 12595a18fff2SAl Viro } 12605a18fff2SAl Viro } 12615a18fff2SAl Viro 12621da177e4SLinus Torvalds path->mnt = mnt; 12631da177e4SLinus Torvalds path->dentry = dentry; 12649875cf80SDavid Howells err = follow_managed(path, nd->flags); 126589312214SIan Kent if (unlikely(err < 0)) { 126689312214SIan Kent path_put_conditional(path, nd); 12679875cf80SDavid Howells return err; 126889312214SIan Kent } 126931e6b01fSNick Piggin *inode = path->dentry->d_inode; 12701da177e4SLinus Torvalds return 0; 12711da177e4SLinus Torvalds } 12721da177e4SLinus Torvalds 127352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 127452094c8aSAl Viro { 127552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 127652094c8aSAl Viro int err = exec_permission(nd->inode, IPERM_FLAG_RCU); 127752094c8aSAl Viro if (err != -ECHILD) 127852094c8aSAl Viro return err; 127919660af7SAl Viro if (unlazy_walk(nd, NULL)) 128052094c8aSAl Viro return -ECHILD; 128152094c8aSAl Viro } 128252094c8aSAl Viro return exec_permission(nd->inode, 0); 128352094c8aSAl Viro } 128452094c8aSAl Viro 12859856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12869856fa1bSAl Viro { 12879856fa1bSAl Viro if (type == LAST_DOTDOT) { 12889856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12899856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12909856fa1bSAl Viro return -ECHILD; 12919856fa1bSAl Viro } else 12929856fa1bSAl Viro follow_dotdot(nd); 12939856fa1bSAl Viro } 12949856fa1bSAl Viro return 0; 12959856fa1bSAl Viro } 12969856fa1bSAl Viro 1297951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1298951361f9SAl Viro { 1299951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1300951361f9SAl Viro path_put(&nd->path); 1301951361f9SAl Viro } else { 1302951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 13035b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1304951361f9SAl Viro nd->root.mnt = NULL; 1305951361f9SAl Viro rcu_read_unlock(); 1306951361f9SAl Viro br_read_unlock(vfsmount_lock); 1307951361f9SAl Viro } 1308951361f9SAl Viro } 1309951361f9SAl Viro 1310ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1311ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1312ce57dfc1SAl Viro { 1313ce57dfc1SAl Viro struct inode *inode; 1314ce57dfc1SAl Viro int err; 1315ce57dfc1SAl Viro /* 1316ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1317ce57dfc1SAl Viro * to be able to know about the current root directory and 1318ce57dfc1SAl Viro * parent relationships. 1319ce57dfc1SAl Viro */ 1320ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1321ce57dfc1SAl Viro return handle_dots(nd, type); 1322ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1323ce57dfc1SAl Viro if (unlikely(err)) { 1324ce57dfc1SAl Viro terminate_walk(nd); 1325ce57dfc1SAl Viro return err; 1326ce57dfc1SAl Viro } 1327ce57dfc1SAl Viro if (!inode) { 1328ce57dfc1SAl Viro path_to_nameidata(path, nd); 1329ce57dfc1SAl Viro terminate_walk(nd); 1330ce57dfc1SAl Viro return -ENOENT; 1331ce57dfc1SAl Viro } 1332ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 133319660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 133419660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 133519660af7SAl Viro terminate_walk(nd); 1336ce57dfc1SAl Viro return -ECHILD; 133719660af7SAl Viro } 133819660af7SAl Viro } 1339ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1340ce57dfc1SAl Viro return 1; 1341ce57dfc1SAl Viro } 1342ce57dfc1SAl Viro path_to_nameidata(path, nd); 1343ce57dfc1SAl Viro nd->inode = inode; 1344ce57dfc1SAl Viro return 0; 1345ce57dfc1SAl Viro } 1346ce57dfc1SAl Viro 13471da177e4SLinus Torvalds /* 1348b356379aSAl Viro * This limits recursive symlink follows to 8, while 1349b356379aSAl Viro * limiting consecutive symlinks to 40. 1350b356379aSAl Viro * 1351b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1352b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1353b356379aSAl Viro */ 1354b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1355b356379aSAl Viro { 1356b356379aSAl Viro int res; 1357b356379aSAl Viro 1358b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1359b356379aSAl Viro path_put_conditional(path, nd); 1360b356379aSAl Viro path_put(&nd->path); 1361b356379aSAl Viro return -ELOOP; 1362b356379aSAl Viro } 13631a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1364b356379aSAl Viro 1365b356379aSAl Viro nd->depth++; 1366b356379aSAl Viro current->link_count++; 1367b356379aSAl Viro 1368b356379aSAl Viro do { 1369b356379aSAl Viro struct path link = *path; 1370b356379aSAl Viro void *cookie; 1371574197e0SAl Viro 1372574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1373b356379aSAl Viro if (!res) 1374b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1375b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1376574197e0SAl Viro put_link(nd, &link, cookie); 1377b356379aSAl Viro } while (res > 0); 1378b356379aSAl Viro 1379b356379aSAl Viro current->link_count--; 1380b356379aSAl Viro nd->depth--; 1381b356379aSAl Viro return res; 1382b356379aSAl Viro } 1383b356379aSAl Viro 1384b356379aSAl Viro /* 13851da177e4SLinus Torvalds * Name resolution. 1386ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1387ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13881da177e4SLinus Torvalds * 1389ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1390ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13911da177e4SLinus Torvalds */ 13926de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13931da177e4SLinus Torvalds { 13941da177e4SLinus Torvalds struct path next; 13951da177e4SLinus Torvalds int err; 13961da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds while (*name=='/') 13991da177e4SLinus Torvalds name++; 14001da177e4SLinus Torvalds if (!*name) 1401086e183aSAl Viro return 0; 14021da177e4SLinus Torvalds 14031da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 14041da177e4SLinus Torvalds for(;;) { 14051da177e4SLinus Torvalds unsigned long hash; 14061da177e4SLinus Torvalds struct qstr this; 14071da177e4SLinus Torvalds unsigned int c; 1408fe479a58SAl Viro int type; 14091da177e4SLinus Torvalds 1410cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 141152094c8aSAl Viro 141252094c8aSAl Viro err = may_lookup(nd); 14131da177e4SLinus Torvalds if (err) 14141da177e4SLinus Torvalds break; 14151da177e4SLinus Torvalds 14161da177e4SLinus Torvalds this.name = name; 14171da177e4SLinus Torvalds c = *(const unsigned char *)name; 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds hash = init_name_hash(); 14201da177e4SLinus Torvalds do { 14211da177e4SLinus Torvalds name++; 14221da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 14231da177e4SLinus Torvalds c = *(const unsigned char *)name; 14241da177e4SLinus Torvalds } while (c && (c != '/')); 14251da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14261da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14271da177e4SLinus Torvalds 1428fe479a58SAl Viro type = LAST_NORM; 1429fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1430fe479a58SAl Viro case 2: 143116c2cd71SAl Viro if (this.name[1] == '.') { 1432fe479a58SAl Viro type = LAST_DOTDOT; 143316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 143416c2cd71SAl Viro } 1435fe479a58SAl Viro break; 1436fe479a58SAl Viro case 1: 1437fe479a58SAl Viro type = LAST_DOT; 1438fe479a58SAl Viro } 14395a202bcdSAl Viro if (likely(type == LAST_NORM)) { 14405a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 144116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14425a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14435a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14445a202bcdSAl Viro &this); 14455a202bcdSAl Viro if (err < 0) 14465a202bcdSAl Viro break; 14475a202bcdSAl Viro } 14485a202bcdSAl Viro } 1449fe479a58SAl Viro 14501da177e4SLinus Torvalds /* remove trailing slashes? */ 14511da177e4SLinus Torvalds if (!c) 14521da177e4SLinus Torvalds goto last_component; 14531da177e4SLinus Torvalds while (*++name == '/'); 14541da177e4SLinus Torvalds if (!*name) 1455b356379aSAl Viro goto last_component; 14561da177e4SLinus Torvalds 1457ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1458ce57dfc1SAl Viro if (err < 0) 1459ce57dfc1SAl Viro return err; 1460fe479a58SAl Viro 1461ce57dfc1SAl Viro if (err) { 1462b356379aSAl Viro err = nested_symlink(&next, nd); 14631da177e4SLinus Torvalds if (err) 1464a7472babSAl Viro return err; 146531e6b01fSNick Piggin } 14661da177e4SLinus Torvalds err = -ENOTDIR; 146731e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14681da177e4SLinus Torvalds break; 14691da177e4SLinus Torvalds continue; 14701da177e4SLinus Torvalds /* here ends the main loop */ 14711da177e4SLinus Torvalds 14721da177e4SLinus Torvalds last_component: 1473f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1474f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1475ce57dfc1SAl Viro nd->last = this; 1476ce57dfc1SAl Viro nd->last_type = type; 1477ce57dfc1SAl Viro return 0; 1478ce57dfc1SAl Viro } 1479951361f9SAl Viro terminate_walk(nd); 14801da177e4SLinus Torvalds return err; 14811da177e4SLinus Torvalds } 14821da177e4SLinus Torvalds 148370e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 148470e9b357SAl Viro struct nameidata *nd, struct file **fp) 148531e6b01fSNick Piggin { 148631e6b01fSNick Piggin int retval = 0; 148731e6b01fSNick Piggin int fput_needed; 148831e6b01fSNick Piggin struct file *file; 148931e6b01fSNick Piggin 149031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 149116c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 149231e6b01fSNick Piggin nd->depth = 0; 14935b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14945b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 149573d049a4SAl Viro if (*name) { 14965b6ca027SAl Viro if (!inode->i_op->lookup) 14975b6ca027SAl Viro return -ENOTDIR; 14985b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14995b6ca027SAl Viro if (retval) 15005b6ca027SAl Viro return retval; 150173d049a4SAl Viro } 15025b6ca027SAl Viro nd->path = nd->root; 15035b6ca027SAl Viro nd->inode = inode; 15045b6ca027SAl Viro if (flags & LOOKUP_RCU) { 15055b6ca027SAl Viro br_read_lock(vfsmount_lock); 15065b6ca027SAl Viro rcu_read_lock(); 15075b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 15085b6ca027SAl Viro } else { 15095b6ca027SAl Viro path_get(&nd->path); 15105b6ca027SAl Viro } 15115b6ca027SAl Viro return 0; 15125b6ca027SAl Viro } 15135b6ca027SAl Viro 151431e6b01fSNick Piggin nd->root.mnt = NULL; 151531e6b01fSNick Piggin 151631e6b01fSNick Piggin if (*name=='/') { 1517e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 151831e6b01fSNick Piggin br_read_lock(vfsmount_lock); 151931e6b01fSNick Piggin rcu_read_lock(); 1520e41f7d4eSAl Viro set_root_rcu(nd); 1521e41f7d4eSAl Viro } else { 1522e41f7d4eSAl Viro set_root(nd); 1523e41f7d4eSAl Viro path_get(&nd->root); 1524e41f7d4eSAl Viro } 152531e6b01fSNick Piggin nd->path = nd->root; 152631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1527e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 152831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1529c28cc364SNick Piggin unsigned seq; 153031e6b01fSNick Piggin 153131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 153231e6b01fSNick Piggin rcu_read_lock(); 153331e6b01fSNick Piggin 1534c28cc364SNick Piggin do { 1535c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 153631e6b01fSNick Piggin nd->path = fs->pwd; 1537c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1538c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1539e41f7d4eSAl Viro } else { 1540e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1541e41f7d4eSAl Viro } 154231e6b01fSNick Piggin } else { 154331e6b01fSNick Piggin struct dentry *dentry; 154431e6b01fSNick Piggin 15451abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 154631e6b01fSNick Piggin retval = -EBADF; 154731e6b01fSNick Piggin if (!file) 154831e6b01fSNick Piggin goto out_fail; 154931e6b01fSNick Piggin 155031e6b01fSNick Piggin dentry = file->f_path.dentry; 155131e6b01fSNick Piggin 1552f52e0c11SAl Viro if (*name) { 155331e6b01fSNick Piggin retval = -ENOTDIR; 155431e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 155531e6b01fSNick Piggin goto fput_fail; 155631e6b01fSNick Piggin 155731e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 155831e6b01fSNick Piggin if (retval) 155931e6b01fSNick Piggin goto fput_fail; 1560f52e0c11SAl Viro } 156131e6b01fSNick Piggin 156231e6b01fSNick Piggin nd->path = file->f_path; 1563e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 156431e6b01fSNick Piggin if (fput_needed) 156570e9b357SAl Viro *fp = file; 1566c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 156731e6b01fSNick Piggin br_read_lock(vfsmount_lock); 156831e6b01fSNick Piggin rcu_read_lock(); 15695590ff0dSUlrich Drepper } else { 15705dd784d0SJan Blunck path_get(&file->f_path); 15715590ff0dSUlrich Drepper fput_light(file, fput_needed); 15721da177e4SLinus Torvalds } 1573e41f7d4eSAl Viro } 1574e41f7d4eSAl Viro 157531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15769b4a9b14SAl Viro return 0; 15772dfdd266SJosef 'Jeff' Sipek 15789b4a9b14SAl Viro fput_fail: 15799b4a9b14SAl Viro fput_light(file, fput_needed); 15809b4a9b14SAl Viro out_fail: 15819b4a9b14SAl Viro return retval; 15829b4a9b14SAl Viro } 15839b4a9b14SAl Viro 1584bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1585bd92d7feSAl Viro { 1586bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1587bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1588bd92d7feSAl Viro 1589bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1590bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1591bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1592bd92d7feSAl Viro } 1593bd92d7feSAl Viro 15949b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1595ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15969b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15979b4a9b14SAl Viro { 159870e9b357SAl Viro struct file *base = NULL; 1599bd92d7feSAl Viro struct path path; 1600bd92d7feSAl Viro int err; 160131e6b01fSNick Piggin 160231e6b01fSNick Piggin /* 160331e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 160431e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 160531e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 160631e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 160731e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 160831e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 160931e6b01fSNick Piggin * analogue, foo_rcu(). 161031e6b01fSNick Piggin * 161131e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 161231e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 161331e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 161431e6b01fSNick Piggin * be able to complete). 161531e6b01fSNick Piggin */ 1616bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1617ee0827cdSAl Viro 1618bd92d7feSAl Viro if (unlikely(err)) 1619bd92d7feSAl Viro return err; 1620ee0827cdSAl Viro 1621ee0827cdSAl Viro current->total_link_count = 0; 1622bd92d7feSAl Viro err = link_path_walk(name, nd); 1623bd92d7feSAl Viro 1624bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1625bd92d7feSAl Viro err = lookup_last(nd, &path); 1626bd92d7feSAl Viro while (err > 0) { 1627bd92d7feSAl Viro void *cookie; 1628bd92d7feSAl Viro struct path link = path; 1629bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1630574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1631bd92d7feSAl Viro if (!err) 1632bd92d7feSAl Viro err = lookup_last(nd, &path); 1633574197e0SAl Viro put_link(nd, &link, cookie); 1634bd92d7feSAl Viro } 1635bd92d7feSAl Viro } 1636ee0827cdSAl Viro 16379f1fafeeSAl Viro if (!err) 16389f1fafeeSAl Viro err = complete_walk(nd); 1639bd92d7feSAl Viro 1640bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1641bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1642bd92d7feSAl Viro path_put(&nd->path); 1643bd23a539SAl Viro err = -ENOTDIR; 1644bd92d7feSAl Viro } 1645bd92d7feSAl Viro } 164616c2cd71SAl Viro 164770e9b357SAl Viro if (base) 164870e9b357SAl Viro fput(base); 1649ee0827cdSAl Viro 16505b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 165131e6b01fSNick Piggin path_put(&nd->root); 165231e6b01fSNick Piggin nd->root.mnt = NULL; 165331e6b01fSNick Piggin } 1654bd92d7feSAl Viro return err; 165531e6b01fSNick Piggin } 165631e6b01fSNick Piggin 1657ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1658ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1659ee0827cdSAl Viro { 1660ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1661ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1662ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1663ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1664ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1665ee0827cdSAl Viro 166631e6b01fSNick Piggin if (likely(!retval)) { 166731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 166831e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 166931e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 167031e6b01fSNick Piggin } 167131e6b01fSNick Piggin } 1672170aa3d0SUlrich Drepper return retval; 16731da177e4SLinus Torvalds } 16741da177e4SLinus Torvalds 1675c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16765590ff0dSUlrich Drepper { 1677c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16785590ff0dSUlrich Drepper } 16795590ff0dSUlrich Drepper 1680d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1681d1811465SAl Viro { 1682d1811465SAl Viro struct nameidata nd; 1683d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1684d1811465SAl Viro if (!res) 1685d1811465SAl Viro *path = nd.path; 1686d1811465SAl Viro return res; 1687d1811465SAl Viro } 1688d1811465SAl Viro 168916f18200SJosef 'Jeff' Sipek /** 169016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 169116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 169216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 169316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 169416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 169516f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 169616f18200SJosef 'Jeff' Sipek */ 169716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 169816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 169916f18200SJosef 'Jeff' Sipek struct nameidata *nd) 170016f18200SJosef 'Jeff' Sipek { 17015b6ca027SAl Viro nd->root.dentry = dentry; 17025b6ca027SAl Viro nd->root.mnt = mnt; 17035b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 17045b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 170516f18200SJosef 'Jeff' Sipek } 170616f18200SJosef 'Jeff' Sipek 1707eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1708eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 17091da177e4SLinus Torvalds { 171081fca444SChristoph Hellwig struct inode *inode = base->d_inode; 17111da177e4SLinus Torvalds struct dentry *dentry; 17121da177e4SLinus Torvalds int err; 17131da177e4SLinus Torvalds 1714b74c79e9SNick Piggin err = exec_permission(inode, 0); 171581fca444SChristoph Hellwig if (err) 171681fca444SChristoph Hellwig return ERR_PTR(err); 17171da177e4SLinus Torvalds 17181da177e4SLinus Torvalds /* 1719b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1720b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1721b04f784eSNick Piggin * a double lookup. 17226e6b1bd1SAl Viro */ 17236e6b1bd1SAl Viro dentry = d_lookup(base, name); 17246e6b1bd1SAl Viro 172544396f4bSJosef Bacik if (dentry && d_need_lookup(dentry)) { 172644396f4bSJosef Bacik /* 172744396f4bSJosef Bacik * __lookup_hash is called with the parent dir's i_mutex already 172844396f4bSJosef Bacik * held, so we are good to go here. 172944396f4bSJosef Bacik */ 173044396f4bSJosef Bacik dentry = d_inode_lookup(base, dentry, nd); 173144396f4bSJosef Bacik if (IS_ERR(dentry)) 173244396f4bSJosef Bacik return dentry; 173344396f4bSJosef Bacik } 173444396f4bSJosef Bacik 1735fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 17366e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 17376e6b1bd1SAl Viro 17381da177e4SLinus Torvalds if (!dentry) 1739baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17405a202bcdSAl Viro 17411da177e4SLinus Torvalds return dentry; 17421da177e4SLinus Torvalds } 17431da177e4SLinus Torvalds 1744057f6c01SJames Morris /* 1745057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1746057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1747057f6c01SJames Morris * SMP-safe. 1748057f6c01SJames Morris */ 1749a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17501da177e4SLinus Torvalds { 17514ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17521da177e4SLinus Torvalds } 17531da177e4SLinus Torvalds 1754eead1911SChristoph Hellwig /** 1755a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1756eead1911SChristoph Hellwig * @name: pathname component to lookup 1757eead1911SChristoph Hellwig * @base: base directory to lookup from 1758eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1759eead1911SChristoph Hellwig * 1760a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1761a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1762eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1763eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1764eead1911SChristoph Hellwig */ 1765057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1766057f6c01SJames Morris { 1767057f6c01SJames Morris struct qstr this; 17686a96ba54SAl Viro unsigned long hash; 17696a96ba54SAl Viro unsigned int c; 1770057f6c01SJames Morris 17712f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17722f9092e1SDavid Woodhouse 17736a96ba54SAl Viro this.name = name; 17746a96ba54SAl Viro this.len = len; 17756a96ba54SAl Viro if (!len) 17766a96ba54SAl Viro return ERR_PTR(-EACCES); 17776a96ba54SAl Viro 17786a96ba54SAl Viro hash = init_name_hash(); 17796a96ba54SAl Viro while (len--) { 17806a96ba54SAl Viro c = *(const unsigned char *)name++; 17816a96ba54SAl Viro if (c == '/' || c == '\0') 17826a96ba54SAl Viro return ERR_PTR(-EACCES); 17836a96ba54SAl Viro hash = partial_name_hash(c, hash); 17846a96ba54SAl Viro } 17856a96ba54SAl Viro this.hash = end_name_hash(hash); 17865a202bcdSAl Viro /* 17875a202bcdSAl Viro * See if the low-level filesystem might want 17885a202bcdSAl Viro * to use its own hash.. 17895a202bcdSAl Viro */ 17905a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17915a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17925a202bcdSAl Viro if (err < 0) 17935a202bcdSAl Viro return ERR_PTR(err); 17945a202bcdSAl Viro } 1795eead1911SChristoph Hellwig 179649705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1797057f6c01SJames Morris } 1798057f6c01SJames Morris 17992d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 18002d8f3038SAl Viro struct path *path) 18011da177e4SLinus Torvalds { 18022d8f3038SAl Viro struct nameidata nd; 1803f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 18041da177e4SLinus Torvalds int err = PTR_ERR(tmp); 18051da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 18062d8f3038SAl Viro 18072d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18082d8f3038SAl Viro 18092d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 18101da177e4SLinus Torvalds putname(tmp); 18112d8f3038SAl Viro if (!err) 18122d8f3038SAl Viro *path = nd.path; 18131da177e4SLinus Torvalds } 18141da177e4SLinus Torvalds return err; 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds 18172ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 18182ad94ae6SAl Viro struct nameidata *nd, char **name) 18192ad94ae6SAl Viro { 18202ad94ae6SAl Viro char *s = getname(path); 18212ad94ae6SAl Viro int error; 18222ad94ae6SAl Viro 18232ad94ae6SAl Viro if (IS_ERR(s)) 18242ad94ae6SAl Viro return PTR_ERR(s); 18252ad94ae6SAl Viro 18262ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 18272ad94ae6SAl Viro if (error) 18282ad94ae6SAl Viro putname(s); 18292ad94ae6SAl Viro else 18302ad94ae6SAl Viro *name = s; 18312ad94ae6SAl Viro 18322ad94ae6SAl Viro return error; 18332ad94ae6SAl Viro } 18342ad94ae6SAl Viro 18351da177e4SLinus Torvalds /* 18361da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18371da177e4SLinus Torvalds * minimal. 18381da177e4SLinus Torvalds */ 18391da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18401da177e4SLinus Torvalds { 1841da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1842da9592edSDavid Howells 18431da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18441da177e4SLinus Torvalds return 0; 1845e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1846e795b717SSerge E. Hallyn goto other_userns; 1847da9592edSDavid Howells if (inode->i_uid == fsuid) 18481da177e4SLinus Torvalds return 0; 1849da9592edSDavid Howells if (dir->i_uid == fsuid) 18501da177e4SLinus Torvalds return 0; 1851e795b717SSerge E. Hallyn 1852e795b717SSerge E. Hallyn other_userns: 1853e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 18541da177e4SLinus Torvalds } 18551da177e4SLinus Torvalds 18561da177e4SLinus Torvalds /* 18571da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18581da177e4SLinus Torvalds * whether the type of victim is right. 18591da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18601da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18611da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18621da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18631da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18641da177e4SLinus Torvalds * a. be owner of dir, or 18651da177e4SLinus Torvalds * b. be owner of victim, or 18661da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18671da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18681da177e4SLinus Torvalds * links pointing to it. 18691da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18701da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18711da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18721da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18731da177e4SLinus Torvalds * nfs_async_unlink(). 18741da177e4SLinus Torvalds */ 1875858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18761da177e4SLinus Torvalds { 18771da177e4SLinus Torvalds int error; 18781da177e4SLinus Torvalds 18791da177e4SLinus Torvalds if (!victim->d_inode) 18801da177e4SLinus Torvalds return -ENOENT; 18811da177e4SLinus Torvalds 18821da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1883cccc6bbaSAl Viro audit_inode_child(victim, dir); 18841da177e4SLinus Torvalds 1885f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18861da177e4SLinus Torvalds if (error) 18871da177e4SLinus Torvalds return error; 18881da177e4SLinus Torvalds if (IS_APPEND(dir)) 18891da177e4SLinus Torvalds return -EPERM; 18901da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1891f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18921da177e4SLinus Torvalds return -EPERM; 18931da177e4SLinus Torvalds if (isdir) { 18941da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18951da177e4SLinus Torvalds return -ENOTDIR; 18961da177e4SLinus Torvalds if (IS_ROOT(victim)) 18971da177e4SLinus Torvalds return -EBUSY; 18981da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18991da177e4SLinus Torvalds return -EISDIR; 19001da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19011da177e4SLinus Torvalds return -ENOENT; 19021da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 19031da177e4SLinus Torvalds return -EBUSY; 19041da177e4SLinus Torvalds return 0; 19051da177e4SLinus Torvalds } 19061da177e4SLinus Torvalds 19071da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 19081da177e4SLinus Torvalds * dir. 19091da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 19101da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 19111da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 19121da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 19131da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 19141da177e4SLinus Torvalds */ 1915a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 19161da177e4SLinus Torvalds { 19171da177e4SLinus Torvalds if (child->d_inode) 19181da177e4SLinus Torvalds return -EEXIST; 19191da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19201da177e4SLinus Torvalds return -ENOENT; 1921f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 19221da177e4SLinus Torvalds } 19231da177e4SLinus Torvalds 19241da177e4SLinus Torvalds /* 19251da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 19261da177e4SLinus Torvalds */ 19271da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 19281da177e4SLinus Torvalds { 19291da177e4SLinus Torvalds struct dentry *p; 19301da177e4SLinus Torvalds 19311da177e4SLinus Torvalds if (p1 == p2) { 1932f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 19331da177e4SLinus Torvalds return NULL; 19341da177e4SLinus Torvalds } 19351da177e4SLinus Torvalds 1936a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19371da177e4SLinus Torvalds 1938e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1939e2761a11SOGAWA Hirofumi if (p) { 1940f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1941f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19421da177e4SLinus Torvalds return p; 19431da177e4SLinus Torvalds } 19441da177e4SLinus Torvalds 1945e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1946e2761a11SOGAWA Hirofumi if (p) { 1947f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1948f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19491da177e4SLinus Torvalds return p; 19501da177e4SLinus Torvalds } 19511da177e4SLinus Torvalds 1952f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1953f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19541da177e4SLinus Torvalds return NULL; 19551da177e4SLinus Torvalds } 19561da177e4SLinus Torvalds 19571da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19581da177e4SLinus Torvalds { 19591b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19601da177e4SLinus Torvalds if (p1 != p2) { 19611b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1962a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19631da177e4SLinus Torvalds } 19641da177e4SLinus Torvalds } 19651da177e4SLinus Torvalds 19661da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19671da177e4SLinus Torvalds struct nameidata *nd) 19681da177e4SLinus Torvalds { 1969a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19701da177e4SLinus Torvalds 19711da177e4SLinus Torvalds if (error) 19721da177e4SLinus Torvalds return error; 19731da177e4SLinus Torvalds 1974acfa4380SAl Viro if (!dir->i_op->create) 19751da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19761da177e4SLinus Torvalds mode &= S_IALLUGO; 19771da177e4SLinus Torvalds mode |= S_IFREG; 19781da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19791da177e4SLinus Torvalds if (error) 19801da177e4SLinus Torvalds return error; 19811da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1982a74574aaSStephen Smalley if (!error) 1983f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19841da177e4SLinus Torvalds return error; 19851da177e4SLinus Torvalds } 19861da177e4SLinus Torvalds 198773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19881da177e4SLinus Torvalds { 19893fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19901da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19911da177e4SLinus Torvalds int error; 19921da177e4SLinus Torvalds 1993bcda7652SAl Viro /* O_PATH? */ 1994bcda7652SAl Viro if (!acc_mode) 1995bcda7652SAl Viro return 0; 1996bcda7652SAl Viro 19971da177e4SLinus Torvalds if (!inode) 19981da177e4SLinus Torvalds return -ENOENT; 19991da177e4SLinus Torvalds 2000c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2001c8fe8f30SChristoph Hellwig case S_IFLNK: 20021da177e4SLinus Torvalds return -ELOOP; 2003c8fe8f30SChristoph Hellwig case S_IFDIR: 2004c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 20051da177e4SLinus Torvalds return -EISDIR; 2006c8fe8f30SChristoph Hellwig break; 2007c8fe8f30SChristoph Hellwig case S_IFBLK: 2008c8fe8f30SChristoph Hellwig case S_IFCHR: 20093fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 20101da177e4SLinus Torvalds return -EACCES; 2011c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2012c8fe8f30SChristoph Hellwig case S_IFIFO: 2013c8fe8f30SChristoph Hellwig case S_IFSOCK: 20141da177e4SLinus Torvalds flag &= ~O_TRUNC; 2015c8fe8f30SChristoph Hellwig break; 20164a3fd211SDave Hansen } 2017b41572e9SDave Hansen 20183fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2019b41572e9SDave Hansen if (error) 2020b41572e9SDave Hansen return error; 20216146f0d5SMimi Zohar 20221da177e4SLinus Torvalds /* 20231da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 20241da177e4SLinus Torvalds */ 20251da177e4SLinus Torvalds if (IS_APPEND(inode)) { 20268737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 20277715b521SAl Viro return -EPERM; 20281da177e4SLinus Torvalds if (flag & O_TRUNC) 20297715b521SAl Viro return -EPERM; 20301da177e4SLinus Torvalds } 20311da177e4SLinus Torvalds 20321da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 20332e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 20347715b521SAl Viro return -EPERM; 20351da177e4SLinus Torvalds 20361da177e4SLinus Torvalds /* 20371da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 20381da177e4SLinus Torvalds */ 2039b65a9cfcSAl Viro return break_lease(inode, flag); 20407715b521SAl Viro } 20417715b521SAl Viro 2042e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20437715b521SAl Viro { 2044e1181ee6SJeff Layton struct path *path = &filp->f_path; 20457715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20467715b521SAl Viro int error = get_write_access(inode); 20471da177e4SLinus Torvalds if (error) 20487715b521SAl Viro return error; 20491da177e4SLinus Torvalds /* 20501da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20511da177e4SLinus Torvalds */ 20521da177e4SLinus Torvalds error = locks_verify_locked(inode); 2053be6d3e56SKentaro Takeda if (!error) 2054ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20551da177e4SLinus Torvalds if (!error) { 20567715b521SAl Viro error = do_truncate(path->dentry, 0, 2057d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2058e1181ee6SJeff Layton filp); 20591da177e4SLinus Torvalds } 20601da177e4SLinus Torvalds put_write_access(inode); 2061acd0c935SMimi Zohar return error; 20621da177e4SLinus Torvalds } 20631da177e4SLinus Torvalds 2064d57999e1SDave Hansen /* 2065d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2066d57999e1SDave Hansen * 00 - read-only 2067d57999e1SDave Hansen * 01 - write-only 2068d57999e1SDave Hansen * 10 - read-write 2069d57999e1SDave Hansen * 11 - special 2070d57999e1SDave Hansen * it is changed into 2071d57999e1SDave Hansen * 00 - no permissions needed 2072d57999e1SDave Hansen * 01 - read-permission 2073d57999e1SDave Hansen * 10 - write-permission 2074d57999e1SDave Hansen * 11 - read-write 2075d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2076d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2077d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2078d57999e1SDave Hansen * later). 2079d57999e1SDave Hansen * 2080d57999e1SDave Hansen */ 2081d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2082d57999e1SDave Hansen { 2083d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2084d57999e1SDave Hansen flag++; 2085d57999e1SDave Hansen return flag; 2086d57999e1SDave Hansen } 2087d57999e1SDave Hansen 208831e6b01fSNick Piggin /* 2089fe2d35ffSAl Viro * Handle the last step of open() 209031e6b01fSNick Piggin */ 2091fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2092c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2093fb1cc555SAl Viro { 2094a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20956c0d46c4SAl Viro struct dentry *dentry; 2096ca344a89SAl Viro int open_flag = op->open_flag; 20976c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2098ca344a89SAl Viro int want_write = 0; 2099bcda7652SAl Viro int acc_mode = op->acc_mode; 2100fb1cc555SAl Viro struct file *filp; 210116c2cd71SAl Viro int error; 2102fb1cc555SAl Viro 2103c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2104c3e380b0SAl Viro nd->flags |= op->intent; 2105c3e380b0SAl Viro 21061f36f774SAl Viro switch (nd->last_type) { 21071f36f774SAl Viro case LAST_DOTDOT: 2108176306f5SNeil Brown case LAST_DOT: 2109fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2110fe2d35ffSAl Viro if (error) 2111fe2d35ffSAl Viro return ERR_PTR(error); 21121f36f774SAl Viro /* fallthrough */ 21131f36f774SAl Viro case LAST_ROOT: 21149f1fafeeSAl Viro error = complete_walk(nd); 211516c2cd71SAl Viro if (error) 21169f1fafeeSAl Viro return ERR_PTR(error); 2117fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2118ca344a89SAl Viro if (open_flag & O_CREAT) { 211916c2cd71SAl Viro error = -EISDIR; 21201f36f774SAl Viro goto exit; 2121fe2d35ffSAl Viro } 2122fe2d35ffSAl Viro goto ok; 21231f36f774SAl Viro case LAST_BIND: 21249f1fafeeSAl Viro error = complete_walk(nd); 212516c2cd71SAl Viro if (error) 21269f1fafeeSAl Viro return ERR_PTR(error); 21271f36f774SAl Viro audit_inode(pathname, dir); 21281f36f774SAl Viro goto ok; 21291f36f774SAl Viro } 2130a2c36b45SAl Viro 2131ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2132bcda7652SAl Viro int symlink_ok = 0; 2133fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2134fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2135bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2136bcda7652SAl Viro symlink_ok = 1; 2137fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2138ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2139ce57dfc1SAl Viro !symlink_ok); 2140ce57dfc1SAl Viro if (error < 0) 2141fe2d35ffSAl Viro return ERR_PTR(error); 2142ce57dfc1SAl Viro if (error) /* symlink */ 2143fe2d35ffSAl Viro return NULL; 2144fe2d35ffSAl Viro /* sayonara */ 21459f1fafeeSAl Viro error = complete_walk(nd); 21469f1fafeeSAl Viro if (error) 2147fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2148fe2d35ffSAl Viro 2149fe2d35ffSAl Viro error = -ENOTDIR; 2150fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2151ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2152fe2d35ffSAl Viro goto exit; 2153fe2d35ffSAl Viro } 2154fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2155fe2d35ffSAl Viro goto ok; 2156fe2d35ffSAl Viro } 2157fe2d35ffSAl Viro 2158fe2d35ffSAl Viro /* create side of things */ 21599f1fafeeSAl Viro error = complete_walk(nd); 21609f1fafeeSAl Viro if (error) 21619f1fafeeSAl Viro return ERR_PTR(error); 2162fe2d35ffSAl Viro 2163fe2d35ffSAl Viro audit_inode(pathname, dir); 216416c2cd71SAl Viro error = -EISDIR; 21651f36f774SAl Viro /* trailing slashes? */ 216631e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21671f36f774SAl Viro goto exit; 21681f36f774SAl Viro 2169a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2170a1e28038SAl Viro 21716c0d46c4SAl Viro dentry = lookup_hash(nd); 21726c0d46c4SAl Viro error = PTR_ERR(dentry); 21736c0d46c4SAl Viro if (IS_ERR(dentry)) { 2174fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2175fb1cc555SAl Viro goto exit; 2176fb1cc555SAl Viro } 2177fb1cc555SAl Viro 21786c0d46c4SAl Viro path->dentry = dentry; 21796c0d46c4SAl Viro path->mnt = nd->path.mnt; 21806c0d46c4SAl Viro 2181fb1cc555SAl Viro /* Negative dentry, just create the file */ 21826c0d46c4SAl Viro if (!dentry->d_inode) { 21836c0d46c4SAl Viro int mode = op->mode; 21846c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21856c0d46c4SAl Viro mode &= ~current_umask(); 2186fb1cc555SAl Viro /* 2187fb1cc555SAl Viro * This write is needed to ensure that a 21886c0d46c4SAl Viro * rw->ro transition does not occur between 2189fb1cc555SAl Viro * the time when the file is created and when 2190fb1cc555SAl Viro * a permanent write count is taken through 2191fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2192fb1cc555SAl Viro */ 2193fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2194fb1cc555SAl Viro if (error) 2195fb1cc555SAl Viro goto exit_mutex_unlock; 2196ca344a89SAl Viro want_write = 1; 21979b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2198ca344a89SAl Viro open_flag &= ~O_TRUNC; 21996c0d46c4SAl Viro will_truncate = 0; 2200bcda7652SAl Viro acc_mode = MAY_OPEN; 22016c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 22026c0d46c4SAl Viro if (error) 22036c0d46c4SAl Viro goto exit_mutex_unlock; 22046c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 22056c0d46c4SAl Viro if (error) 22066c0d46c4SAl Viro goto exit_mutex_unlock; 22076c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 22086c0d46c4SAl Viro dput(nd->path.dentry); 22096c0d46c4SAl Viro nd->path.dentry = dentry; 2210ca344a89SAl Viro goto common; 2211fb1cc555SAl Viro } 2212fb1cc555SAl Viro 2213fb1cc555SAl Viro /* 2214fb1cc555SAl Viro * It already exists. 2215fb1cc555SAl Viro */ 2216fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2217fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2218fb1cc555SAl Viro 2219fb1cc555SAl Viro error = -EEXIST; 2220ca344a89SAl Viro if (open_flag & O_EXCL) 2221fb1cc555SAl Viro goto exit_dput; 2222fb1cc555SAl Viro 22239875cf80SDavid Howells error = follow_managed(path, nd->flags); 22249875cf80SDavid Howells if (error < 0) 2225fb1cc555SAl Viro goto exit_dput; 2226fb1cc555SAl Viro 2227fb1cc555SAl Viro error = -ENOENT; 2228fb1cc555SAl Viro if (!path->dentry->d_inode) 2229fb1cc555SAl Viro goto exit_dput; 22309e67f361SAl Viro 22319e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2232fb1cc555SAl Viro return NULL; 2233fb1cc555SAl Viro 2234fb1cc555SAl Viro path_to_nameidata(path, nd); 223531e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2236fb1cc555SAl Viro error = -EISDIR; 223731e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2238fb1cc555SAl Viro goto exit; 223967ee3ad2SAl Viro ok: 22406c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22416c0d46c4SAl Viro will_truncate = 0; 22426c0d46c4SAl Viro 22430f9d1a10SAl Viro if (will_truncate) { 22440f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22450f9d1a10SAl Viro if (error) 22460f9d1a10SAl Viro goto exit; 2247ca344a89SAl Viro want_write = 1; 22480f9d1a10SAl Viro } 2249ca344a89SAl Viro common: 2250bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2251ca344a89SAl Viro if (error) 22520f9d1a10SAl Viro goto exit; 22530f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22540f9d1a10SAl Viro if (!IS_ERR(filp)) { 22550f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22560f9d1a10SAl Viro if (error) { 22570f9d1a10SAl Viro fput(filp); 22580f9d1a10SAl Viro filp = ERR_PTR(error); 22590f9d1a10SAl Viro } 22600f9d1a10SAl Viro } 22610f9d1a10SAl Viro if (!IS_ERR(filp)) { 22620f9d1a10SAl Viro if (will_truncate) { 22630f9d1a10SAl Viro error = handle_truncate(filp); 22640f9d1a10SAl Viro if (error) { 22650f9d1a10SAl Viro fput(filp); 22660f9d1a10SAl Viro filp = ERR_PTR(error); 22670f9d1a10SAl Viro } 22680f9d1a10SAl Viro } 22690f9d1a10SAl Viro } 2270ca344a89SAl Viro out: 2271ca344a89SAl Viro if (want_write) 22720f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22730f9d1a10SAl Viro path_put(&nd->path); 2274fb1cc555SAl Viro return filp; 2275fb1cc555SAl Viro 2276fb1cc555SAl Viro exit_mutex_unlock: 2277fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2278fb1cc555SAl Viro exit_dput: 2279fb1cc555SAl Viro path_put_conditional(path, nd); 2280fb1cc555SAl Viro exit: 2281ca344a89SAl Viro filp = ERR_PTR(error); 2282ca344a89SAl Viro goto out; 2283fb1cc555SAl Viro } 2284fb1cc555SAl Viro 228513aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 228673d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22871da177e4SLinus Torvalds { 2288fe2d35ffSAl Viro struct file *base = NULL; 22894a3fd211SDave Hansen struct file *filp; 22909850c056SAl Viro struct path path; 229113aab428SAl Viro int error; 229231e6b01fSNick Piggin 229331e6b01fSNick Piggin filp = get_empty_filp(); 229431e6b01fSNick Piggin if (!filp) 229531e6b01fSNick Piggin return ERR_PTR(-ENFILE); 229631e6b01fSNick Piggin 229747c805dcSAl Viro filp->f_flags = op->open_flag; 229873d049a4SAl Viro nd->intent.open.file = filp; 229973d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 230073d049a4SAl Viro nd->intent.open.create_mode = op->mode; 230131e6b01fSNick Piggin 230273d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 230331e6b01fSNick Piggin if (unlikely(error)) 230413aab428SAl Viro goto out_filp; 230531e6b01fSNick Piggin 2306fe2d35ffSAl Viro current->total_link_count = 0; 230773d049a4SAl Viro error = link_path_walk(pathname, nd); 230831e6b01fSNick Piggin if (unlikely(error)) 230931e6b01fSNick Piggin goto out_filp; 23101da177e4SLinus Torvalds 231173d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2312806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 23137b9337aaSNick Piggin struct path link = path; 2314def4af30SAl Viro void *cookie; 2315574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 231673d049a4SAl Viro path_put_conditional(&path, nd); 231773d049a4SAl Viro path_put(&nd->path); 231840b39136SAl Viro filp = ERR_PTR(-ELOOP); 231940b39136SAl Viro break; 232040b39136SAl Viro } 232173d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 232273d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2323574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2324c3e380b0SAl Viro if (unlikely(error)) 2325f1afe9efSAl Viro filp = ERR_PTR(error); 2326c3e380b0SAl Viro else 232773d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2328574197e0SAl Viro put_link(nd, &link, cookie); 2329806b681cSAl Viro } 233010fa8e62SAl Viro out: 233173d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 233273d049a4SAl Viro path_put(&nd->root); 2333fe2d35ffSAl Viro if (base) 2334fe2d35ffSAl Viro fput(base); 233573d049a4SAl Viro release_open_intent(nd); 233610fa8e62SAl Viro return filp; 23371da177e4SLinus Torvalds 233831e6b01fSNick Piggin out_filp: 233910fa8e62SAl Viro filp = ERR_PTR(error); 234010fa8e62SAl Viro goto out; 2341de459215SKirill Korotaev } 23421da177e4SLinus Torvalds 234313aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 234413aab428SAl Viro const struct open_flags *op, int flags) 234513aab428SAl Viro { 234673d049a4SAl Viro struct nameidata nd; 234713aab428SAl Viro struct file *filp; 234813aab428SAl Viro 234973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 235013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 235173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 235213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 235373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 235413aab428SAl Viro return filp; 235513aab428SAl Viro } 235613aab428SAl Viro 235773d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 235873d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 235973d049a4SAl Viro { 236073d049a4SAl Viro struct nameidata nd; 236173d049a4SAl Viro struct file *file; 236273d049a4SAl Viro 236373d049a4SAl Viro nd.root.mnt = mnt; 236473d049a4SAl Viro nd.root.dentry = dentry; 236573d049a4SAl Viro 236673d049a4SAl Viro flags |= LOOKUP_ROOT; 236773d049a4SAl Viro 2368bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 236973d049a4SAl Viro return ERR_PTR(-ELOOP); 237073d049a4SAl Viro 237173d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 237273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 237373d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 237473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 237573d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 237673d049a4SAl Viro return file; 237773d049a4SAl Viro } 237873d049a4SAl Viro 23791da177e4SLinus Torvalds /** 23801da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23811da177e4SLinus Torvalds * @nd: nameidata info 23821da177e4SLinus Torvalds * @is_dir: directory flag 23831da177e4SLinus Torvalds * 23841da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23851da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2386c663e5d8SChristoph Hellwig * 23874ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23881da177e4SLinus Torvalds */ 23891da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23901da177e4SLinus Torvalds { 2391c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23921da177e4SLinus Torvalds 23934ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2394c663e5d8SChristoph Hellwig /* 2395c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2396c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2397c663e5d8SChristoph Hellwig */ 23981da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23991da177e4SLinus Torvalds goto fail; 24001da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 24013516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2402a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2403c663e5d8SChristoph Hellwig 2404c663e5d8SChristoph Hellwig /* 2405c663e5d8SChristoph Hellwig * Do the final lookup. 2406c663e5d8SChristoph Hellwig */ 240749705b77SChristoph Hellwig dentry = lookup_hash(nd); 24081da177e4SLinus Torvalds if (IS_ERR(dentry)) 24091da177e4SLinus Torvalds goto fail; 2410c663e5d8SChristoph Hellwig 2411e9baf6e5SAl Viro if (dentry->d_inode) 2412e9baf6e5SAl Viro goto eexist; 2413c663e5d8SChristoph Hellwig /* 2414c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2415c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2416c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2417c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2418c663e5d8SChristoph Hellwig */ 2419e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 24201da177e4SLinus Torvalds dput(dentry); 24211da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2422e9baf6e5SAl Viro } 2423e9baf6e5SAl Viro return dentry; 2424e9baf6e5SAl Viro eexist: 2425e9baf6e5SAl Viro dput(dentry); 2426e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 24271da177e4SLinus Torvalds fail: 24281da177e4SLinus Torvalds return dentry; 24291da177e4SLinus Torvalds } 2430f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 24311da177e4SLinus Torvalds 24321da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24331da177e4SLinus Torvalds { 2434a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24351da177e4SLinus Torvalds 24361da177e4SLinus Torvalds if (error) 24371da177e4SLinus Torvalds return error; 24381da177e4SLinus Torvalds 2439e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2440e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 24411da177e4SLinus Torvalds return -EPERM; 24421da177e4SLinus Torvalds 2443acfa4380SAl Viro if (!dir->i_op->mknod) 24441da177e4SLinus Torvalds return -EPERM; 24451da177e4SLinus Torvalds 244608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 244708ce5f16SSerge E. Hallyn if (error) 244808ce5f16SSerge E. Hallyn return error; 244908ce5f16SSerge E. Hallyn 24501da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24511da177e4SLinus Torvalds if (error) 24521da177e4SLinus Torvalds return error; 24531da177e4SLinus Torvalds 24541da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2455a74574aaSStephen Smalley if (!error) 2456f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24571da177e4SLinus Torvalds return error; 24581da177e4SLinus Torvalds } 24591da177e4SLinus Torvalds 2460463c3197SDave Hansen static int may_mknod(mode_t mode) 2461463c3197SDave Hansen { 2462463c3197SDave Hansen switch (mode & S_IFMT) { 2463463c3197SDave Hansen case S_IFREG: 2464463c3197SDave Hansen case S_IFCHR: 2465463c3197SDave Hansen case S_IFBLK: 2466463c3197SDave Hansen case S_IFIFO: 2467463c3197SDave Hansen case S_IFSOCK: 2468463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2469463c3197SDave Hansen return 0; 2470463c3197SDave Hansen case S_IFDIR: 2471463c3197SDave Hansen return -EPERM; 2472463c3197SDave Hansen default: 2473463c3197SDave Hansen return -EINVAL; 2474463c3197SDave Hansen } 2475463c3197SDave Hansen } 2476463c3197SDave Hansen 24772e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24782e4d0924SHeiko Carstens unsigned, dev) 24791da177e4SLinus Torvalds { 24802ad94ae6SAl Viro int error; 24811da177e4SLinus Torvalds char *tmp; 24821da177e4SLinus Torvalds struct dentry *dentry; 24831da177e4SLinus Torvalds struct nameidata nd; 24841da177e4SLinus Torvalds 24851da177e4SLinus Torvalds if (S_ISDIR(mode)) 24861da177e4SLinus Torvalds return -EPERM; 24871da177e4SLinus Torvalds 24882ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24891da177e4SLinus Torvalds if (error) 24902ad94ae6SAl Viro return error; 24912ad94ae6SAl Viro 24921da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2493463c3197SDave Hansen if (IS_ERR(dentry)) { 24941da177e4SLinus Torvalds error = PTR_ERR(dentry); 2495463c3197SDave Hansen goto out_unlock; 2496463c3197SDave Hansen } 24974ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2498ce3b0f8dSAl Viro mode &= ~current_umask(); 2499463c3197SDave Hansen error = may_mknod(mode); 2500463c3197SDave Hansen if (error) 2501463c3197SDave Hansen goto out_dput; 2502463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2503463c3197SDave Hansen if (error) 2504463c3197SDave Hansen goto out_dput; 2505be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2506be6d3e56SKentaro Takeda if (error) 2507be6d3e56SKentaro Takeda goto out_drop_write; 25081da177e4SLinus Torvalds switch (mode & S_IFMT) { 25091da177e4SLinus Torvalds case 0: case S_IFREG: 25104ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 25111da177e4SLinus Torvalds break; 25121da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 25134ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 25141da177e4SLinus Torvalds new_decode_dev(dev)); 25151da177e4SLinus Torvalds break; 25161da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 25174ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 25181da177e4SLinus Torvalds break; 25191da177e4SLinus Torvalds } 2520be6d3e56SKentaro Takeda out_drop_write: 2521463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2522463c3197SDave Hansen out_dput: 25231da177e4SLinus Torvalds dput(dentry); 2524463c3197SDave Hansen out_unlock: 25254ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25261d957f9bSJan Blunck path_put(&nd.path); 25271da177e4SLinus Torvalds putname(tmp); 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds return error; 25301da177e4SLinus Torvalds } 25311da177e4SLinus Torvalds 25323480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25335590ff0dSUlrich Drepper { 25345590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25355590ff0dSUlrich Drepper } 25365590ff0dSUlrich Drepper 25371da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25381da177e4SLinus Torvalds { 2539a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25401da177e4SLinus Torvalds 25411da177e4SLinus Torvalds if (error) 25421da177e4SLinus Torvalds return error; 25431da177e4SLinus Torvalds 2544acfa4380SAl Viro if (!dir->i_op->mkdir) 25451da177e4SLinus Torvalds return -EPERM; 25461da177e4SLinus Torvalds 25471da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25481da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25491da177e4SLinus Torvalds if (error) 25501da177e4SLinus Torvalds return error; 25511da177e4SLinus Torvalds 25521da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2553a74574aaSStephen Smalley if (!error) 2554f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25551da177e4SLinus Torvalds return error; 25561da177e4SLinus Torvalds } 25571da177e4SLinus Torvalds 25582e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25591da177e4SLinus Torvalds { 25601da177e4SLinus Torvalds int error = 0; 25611da177e4SLinus Torvalds char * tmp; 25626902d925SDave Hansen struct dentry *dentry; 25636902d925SDave Hansen struct nameidata nd; 25641da177e4SLinus Torvalds 25652ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25662ad94ae6SAl Viro if (error) 25676902d925SDave Hansen goto out_err; 25681da177e4SLinus Torvalds 25691da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25701da177e4SLinus Torvalds error = PTR_ERR(dentry); 25716902d925SDave Hansen if (IS_ERR(dentry)) 25726902d925SDave Hansen goto out_unlock; 25736902d925SDave Hansen 25744ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2575ce3b0f8dSAl Viro mode &= ~current_umask(); 2576463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2577463c3197SDave Hansen if (error) 2578463c3197SDave Hansen goto out_dput; 2579be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2580be6d3e56SKentaro Takeda if (error) 2581be6d3e56SKentaro Takeda goto out_drop_write; 25824ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2583be6d3e56SKentaro Takeda out_drop_write: 2584463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2585463c3197SDave Hansen out_dput: 25861da177e4SLinus Torvalds dput(dentry); 25876902d925SDave Hansen out_unlock: 25884ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25891d957f9bSJan Blunck path_put(&nd.path); 25901da177e4SLinus Torvalds putname(tmp); 25916902d925SDave Hansen out_err: 25921da177e4SLinus Torvalds return error; 25931da177e4SLinus Torvalds } 25941da177e4SLinus Torvalds 25953cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25965590ff0dSUlrich Drepper { 25975590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25985590ff0dSUlrich Drepper } 25995590ff0dSUlrich Drepper 26001da177e4SLinus Torvalds /* 2601a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2602a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2603a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2604a71905f0SSage Weil * then we drop the dentry now. 26051da177e4SLinus Torvalds * 26061da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 26071da177e4SLinus Torvalds * do a 26081da177e4SLinus Torvalds * 26091da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 26101da177e4SLinus Torvalds * return -EBUSY; 26111da177e4SLinus Torvalds * 26121da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 26131da177e4SLinus Torvalds * that is still in use by something else.. 26141da177e4SLinus Torvalds */ 26151da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 26161da177e4SLinus Torvalds { 26171da177e4SLinus Torvalds shrink_dcache_parent(dentry); 26181da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 261964252c75SSage Weil if (dentry->d_count == 1) 26201da177e4SLinus Torvalds __d_drop(dentry); 26211da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 26221da177e4SLinus Torvalds } 26231da177e4SLinus Torvalds 26241da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 26251da177e4SLinus Torvalds { 26261da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26271da177e4SLinus Torvalds 26281da177e4SLinus Torvalds if (error) 26291da177e4SLinus Torvalds return error; 26301da177e4SLinus Torvalds 2631acfa4380SAl Viro if (!dir->i_op->rmdir) 26321da177e4SLinus Torvalds return -EPERM; 26331da177e4SLinus Torvalds 26341b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2635912dbc15SSage Weil 26361da177e4SLinus Torvalds error = -EBUSY; 2637912dbc15SSage Weil if (d_mountpoint(dentry)) 2638912dbc15SSage Weil goto out; 2639912dbc15SSage Weil 26401da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2641912dbc15SSage Weil if (error) 2642912dbc15SSage Weil goto out; 2643912dbc15SSage Weil 26443cebde24SSage Weil shrink_dcache_parent(dentry); 26451da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2646912dbc15SSage Weil if (error) 2647912dbc15SSage Weil goto out; 2648912dbc15SSage Weil 26491da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2650d83c49f3SAl Viro dont_mount(dentry); 26511da177e4SLinus Torvalds 2652912dbc15SSage Weil out: 2653912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 2654912dbc15SSage Weil if (!error) 2655912dbc15SSage Weil d_delete(dentry); 26561da177e4SLinus Torvalds return error; 26571da177e4SLinus Torvalds } 26581da177e4SLinus Torvalds 26595590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26601da177e4SLinus Torvalds { 26611da177e4SLinus Torvalds int error = 0; 26621da177e4SLinus Torvalds char * name; 26631da177e4SLinus Torvalds struct dentry *dentry; 26641da177e4SLinus Torvalds struct nameidata nd; 26651da177e4SLinus Torvalds 26662ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26671da177e4SLinus Torvalds if (error) 26682ad94ae6SAl Viro return error; 26691da177e4SLinus Torvalds 26701da177e4SLinus Torvalds switch(nd.last_type) { 26711da177e4SLinus Torvalds case LAST_DOTDOT: 26721da177e4SLinus Torvalds error = -ENOTEMPTY; 26731da177e4SLinus Torvalds goto exit1; 26741da177e4SLinus Torvalds case LAST_DOT: 26751da177e4SLinus Torvalds error = -EINVAL; 26761da177e4SLinus Torvalds goto exit1; 26771da177e4SLinus Torvalds case LAST_ROOT: 26781da177e4SLinus Torvalds error = -EBUSY; 26791da177e4SLinus Torvalds goto exit1; 26801da177e4SLinus Torvalds } 26810612d9fbSOGAWA Hirofumi 26820612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26830612d9fbSOGAWA Hirofumi 26844ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 268549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26861da177e4SLinus Torvalds error = PTR_ERR(dentry); 26876902d925SDave Hansen if (IS_ERR(dentry)) 26886902d925SDave Hansen goto exit2; 2689e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2690e6bc45d6STheodore Ts'o error = -ENOENT; 2691e6bc45d6STheodore Ts'o goto exit3; 2692e6bc45d6STheodore Ts'o } 26930622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26940622753bSDave Hansen if (error) 26950622753bSDave Hansen goto exit3; 2696be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2697be6d3e56SKentaro Takeda if (error) 2698be6d3e56SKentaro Takeda goto exit4; 26994ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2700be6d3e56SKentaro Takeda exit4: 27010622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27020622753bSDave Hansen exit3: 27031da177e4SLinus Torvalds dput(dentry); 27046902d925SDave Hansen exit2: 27054ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27061da177e4SLinus Torvalds exit1: 27071d957f9bSJan Blunck path_put(&nd.path); 27081da177e4SLinus Torvalds putname(name); 27091da177e4SLinus Torvalds return error; 27101da177e4SLinus Torvalds } 27111da177e4SLinus Torvalds 27123cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 27135590ff0dSUlrich Drepper { 27145590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 27155590ff0dSUlrich Drepper } 27165590ff0dSUlrich Drepper 27171da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 27181da177e4SLinus Torvalds { 27191da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 27201da177e4SLinus Torvalds 27211da177e4SLinus Torvalds if (error) 27221da177e4SLinus Torvalds return error; 27231da177e4SLinus Torvalds 2724acfa4380SAl Viro if (!dir->i_op->unlink) 27251da177e4SLinus Torvalds return -EPERM; 27261da177e4SLinus Torvalds 27271b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 27281da177e4SLinus Torvalds if (d_mountpoint(dentry)) 27291da177e4SLinus Torvalds error = -EBUSY; 27301da177e4SLinus Torvalds else { 27311da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2732bec1052eSAl Viro if (!error) { 27331da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2734bec1052eSAl Viro if (!error) 2735d83c49f3SAl Viro dont_mount(dentry); 2736bec1052eSAl Viro } 27371da177e4SLinus Torvalds } 27381b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27391da177e4SLinus Torvalds 27401da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27411da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2742ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27431da177e4SLinus Torvalds d_delete(dentry); 27441da177e4SLinus Torvalds } 27450eeca283SRobert Love 27461da177e4SLinus Torvalds return error; 27471da177e4SLinus Torvalds } 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds /* 27501da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27511b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27521da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27531da177e4SLinus Torvalds * while waiting on the I/O. 27541da177e4SLinus Torvalds */ 27555590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27561da177e4SLinus Torvalds { 27572ad94ae6SAl Viro int error; 27581da177e4SLinus Torvalds char *name; 27591da177e4SLinus Torvalds struct dentry *dentry; 27601da177e4SLinus Torvalds struct nameidata nd; 27611da177e4SLinus Torvalds struct inode *inode = NULL; 27621da177e4SLinus Torvalds 27632ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27641da177e4SLinus Torvalds if (error) 27652ad94ae6SAl Viro return error; 27662ad94ae6SAl Viro 27671da177e4SLinus Torvalds error = -EISDIR; 27681da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27691da177e4SLinus Torvalds goto exit1; 27700612d9fbSOGAWA Hirofumi 27710612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27720612d9fbSOGAWA Hirofumi 27734ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 277449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27751da177e4SLinus Torvalds error = PTR_ERR(dentry); 27761da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27771da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 277850338b88STörök Edwin if (nd.last.name[nd.last.len]) 277950338b88STörök Edwin goto slashes; 27801da177e4SLinus Torvalds inode = dentry->d_inode; 278150338b88STörök Edwin if (!inode) 2782e6bc45d6STheodore Ts'o goto slashes; 27837de9c6eeSAl Viro ihold(inode); 27840622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27850622753bSDave Hansen if (error) 27860622753bSDave Hansen goto exit2; 2787be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2788be6d3e56SKentaro Takeda if (error) 2789be6d3e56SKentaro Takeda goto exit3; 27904ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2791be6d3e56SKentaro Takeda exit3: 27920622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27931da177e4SLinus Torvalds exit2: 27941da177e4SLinus Torvalds dput(dentry); 27951da177e4SLinus Torvalds } 27964ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27971da177e4SLinus Torvalds if (inode) 27981da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27991da177e4SLinus Torvalds exit1: 28001d957f9bSJan Blunck path_put(&nd.path); 28011da177e4SLinus Torvalds putname(name); 28021da177e4SLinus Torvalds return error; 28031da177e4SLinus Torvalds 28041da177e4SLinus Torvalds slashes: 28051da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 28061da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 28071da177e4SLinus Torvalds goto exit2; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 28102e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 28115590ff0dSUlrich Drepper { 28125590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 28135590ff0dSUlrich Drepper return -EINVAL; 28145590ff0dSUlrich Drepper 28155590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 28165590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 28175590ff0dSUlrich Drepper 28185590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 28195590ff0dSUlrich Drepper } 28205590ff0dSUlrich Drepper 28213480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 28225590ff0dSUlrich Drepper { 28235590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 28245590ff0dSUlrich Drepper } 28255590ff0dSUlrich Drepper 2826db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 28271da177e4SLinus Torvalds { 2828a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28291da177e4SLinus Torvalds 28301da177e4SLinus Torvalds if (error) 28311da177e4SLinus Torvalds return error; 28321da177e4SLinus Torvalds 2833acfa4380SAl Viro if (!dir->i_op->symlink) 28341da177e4SLinus Torvalds return -EPERM; 28351da177e4SLinus Torvalds 28361da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28371da177e4SLinus Torvalds if (error) 28381da177e4SLinus Torvalds return error; 28391da177e4SLinus Torvalds 28401da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2841a74574aaSStephen Smalley if (!error) 2842f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28431da177e4SLinus Torvalds return error; 28441da177e4SLinus Torvalds } 28451da177e4SLinus Torvalds 28462e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28472e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28481da177e4SLinus Torvalds { 28492ad94ae6SAl Viro int error; 28501da177e4SLinus Torvalds char *from; 28511da177e4SLinus Torvalds char *to; 28526902d925SDave Hansen struct dentry *dentry; 28536902d925SDave Hansen struct nameidata nd; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds from = getname(oldname); 28561da177e4SLinus Torvalds if (IS_ERR(from)) 28571da177e4SLinus Torvalds return PTR_ERR(from); 28582ad94ae6SAl Viro 28592ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28602ad94ae6SAl Viro if (error) 28616902d925SDave Hansen goto out_putname; 28621da177e4SLinus Torvalds 28631da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28641da177e4SLinus Torvalds error = PTR_ERR(dentry); 28656902d925SDave Hansen if (IS_ERR(dentry)) 28666902d925SDave Hansen goto out_unlock; 28676902d925SDave Hansen 286875c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 286975c3f29dSDave Hansen if (error) 287075c3f29dSDave Hansen goto out_dput; 2871be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2872be6d3e56SKentaro Takeda if (error) 2873be6d3e56SKentaro Takeda goto out_drop_write; 2874db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2875be6d3e56SKentaro Takeda out_drop_write: 287675c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 287775c3f29dSDave Hansen out_dput: 28781da177e4SLinus Torvalds dput(dentry); 28796902d925SDave Hansen out_unlock: 28804ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28811d957f9bSJan Blunck path_put(&nd.path); 28821da177e4SLinus Torvalds putname(to); 28836902d925SDave Hansen out_putname: 28841da177e4SLinus Torvalds putname(from); 28851da177e4SLinus Torvalds return error; 28861da177e4SLinus Torvalds } 28871da177e4SLinus Torvalds 28883480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28895590ff0dSUlrich Drepper { 28905590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28915590ff0dSUlrich Drepper } 28925590ff0dSUlrich Drepper 28931da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28941da177e4SLinus Torvalds { 28951da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28961da177e4SLinus Torvalds int error; 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds if (!inode) 28991da177e4SLinus Torvalds return -ENOENT; 29001da177e4SLinus Torvalds 2901a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 29021da177e4SLinus Torvalds if (error) 29031da177e4SLinus Torvalds return error; 29041da177e4SLinus Torvalds 29051da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 29061da177e4SLinus Torvalds return -EXDEV; 29071da177e4SLinus Torvalds 29081da177e4SLinus Torvalds /* 29091da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 29101da177e4SLinus Torvalds */ 29111da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 29121da177e4SLinus Torvalds return -EPERM; 2913acfa4380SAl Viro if (!dir->i_op->link) 29141da177e4SLinus Torvalds return -EPERM; 29157e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 29161da177e4SLinus Torvalds return -EPERM; 29171da177e4SLinus Torvalds 29181da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 29191da177e4SLinus Torvalds if (error) 29201da177e4SLinus Torvalds return error; 29211da177e4SLinus Torvalds 29227e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2923aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2924aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2925aae8a97dSAneesh Kumar K.V error = -ENOENT; 2926aae8a97dSAneesh Kumar K.V else 29271da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 29287e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2929e31e14ecSStephen Smalley if (!error) 29307e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 29311da177e4SLinus Torvalds return error; 29321da177e4SLinus Torvalds } 29331da177e4SLinus Torvalds 29341da177e4SLinus Torvalds /* 29351da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29361da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29371da177e4SLinus Torvalds * newname. --KAB 29381da177e4SLinus Torvalds * 29391da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29401da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29411da177e4SLinus Torvalds * and other special files. --ADM 29421da177e4SLinus Torvalds */ 29432e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29442e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29451da177e4SLinus Torvalds { 29461da177e4SLinus Torvalds struct dentry *new_dentry; 29472d8f3038SAl Viro struct nameidata nd; 29482d8f3038SAl Viro struct path old_path; 294911a7b371SAneesh Kumar K.V int how = 0; 29501da177e4SLinus Torvalds int error; 29511da177e4SLinus Torvalds char *to; 29521da177e4SLinus Torvalds 295311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2954c04030e1SUlrich Drepper return -EINVAL; 295511a7b371SAneesh Kumar K.V /* 295611a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 295711a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 295811a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 295911a7b371SAneesh Kumar K.V */ 296011a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 296111a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 296211a7b371SAneesh Kumar K.V return -ENOENT; 296311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 296411a7b371SAneesh Kumar K.V } 2965c04030e1SUlrich Drepper 296611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 296711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 296811a7b371SAneesh Kumar K.V 296911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29701da177e4SLinus Torvalds if (error) 29712ad94ae6SAl Viro return error; 29722ad94ae6SAl Viro 29732ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29741da177e4SLinus Torvalds if (error) 29751da177e4SLinus Torvalds goto out; 29761da177e4SLinus Torvalds error = -EXDEV; 29772d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29781da177e4SLinus Torvalds goto out_release; 29791da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29801da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29816902d925SDave Hansen if (IS_ERR(new_dentry)) 29826902d925SDave Hansen goto out_unlock; 298375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 298475c3f29dSDave Hansen if (error) 298575c3f29dSDave Hansen goto out_dput; 2986be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2987be6d3e56SKentaro Takeda if (error) 2988be6d3e56SKentaro Takeda goto out_drop_write; 29892d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2990be6d3e56SKentaro Takeda out_drop_write: 299175c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 299275c3f29dSDave Hansen out_dput: 29931da177e4SLinus Torvalds dput(new_dentry); 29946902d925SDave Hansen out_unlock: 29954ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29961da177e4SLinus Torvalds out_release: 29971d957f9bSJan Blunck path_put(&nd.path); 29982ad94ae6SAl Viro putname(to); 29991da177e4SLinus Torvalds out: 30002d8f3038SAl Viro path_put(&old_path); 30011da177e4SLinus Torvalds 30021da177e4SLinus Torvalds return error; 30031da177e4SLinus Torvalds } 30041da177e4SLinus Torvalds 30053480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 30065590ff0dSUlrich Drepper { 3007c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 30085590ff0dSUlrich Drepper } 30095590ff0dSUlrich Drepper 30101da177e4SLinus Torvalds /* 30111da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 30121da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 30131da177e4SLinus Torvalds * Problems: 30141da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 30151da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 30161da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3017a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 30181da177e4SLinus Torvalds * story. 30191da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 30201b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 30211da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 30221da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3023a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 30241da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 30251da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 30261da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3027a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 30281da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 30291da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 30301da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3031e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 30321b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 30331da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3034c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 30351da177e4SLinus Torvalds * locking]. 30361da177e4SLinus Torvalds */ 303775c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30381da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30391da177e4SLinus Torvalds { 30401da177e4SLinus Torvalds int error = 0; 30419055cba7SSage Weil struct inode *target = new_dentry->d_inode; 30421da177e4SLinus Torvalds 30431da177e4SLinus Torvalds /* 30441da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30451da177e4SLinus Torvalds * we'll need to flip '..'. 30461da177e4SLinus Torvalds */ 30471da177e4SLinus Torvalds if (new_dir != old_dir) { 3048f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30491da177e4SLinus Torvalds if (error) 30501da177e4SLinus Torvalds return error; 30511da177e4SLinus Torvalds } 30521da177e4SLinus Torvalds 30531da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30541da177e4SLinus Torvalds if (error) 30551da177e4SLinus Torvalds return error; 30561da177e4SLinus Torvalds 3057d83c49f3SAl Viro if (target) 30581b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30599055cba7SSage Weil 30601da177e4SLinus Torvalds error = -EBUSY; 30619055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 30629055cba7SSage Weil goto out; 30639055cba7SSage Weil 30643cebde24SSage Weil if (target) 30653cebde24SSage Weil shrink_dcache_parent(new_dentry); 30661da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30679055cba7SSage Weil if (error) 30689055cba7SSage Weil goto out; 30699055cba7SSage Weil 30701da177e4SLinus Torvalds if (target) { 30711da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3072d83c49f3SAl Viro dont_mount(new_dentry); 3073d83c49f3SAl Viro } 30749055cba7SSage Weil out: 30759055cba7SSage Weil if (target) 30761b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 3077e31e14ecSStephen Smalley if (!error) 3078349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30791da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30801da177e4SLinus Torvalds return error; 30811da177e4SLinus Torvalds } 30821da177e4SLinus Torvalds 308375c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30841da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30851da177e4SLinus Torvalds { 308651892bbbSSage Weil struct inode *target = new_dentry->d_inode; 30871da177e4SLinus Torvalds int error; 30881da177e4SLinus Torvalds 30891da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30901da177e4SLinus Torvalds if (error) 30911da177e4SLinus Torvalds return error; 30921da177e4SLinus Torvalds 30931da177e4SLinus Torvalds dget(new_dentry); 30941da177e4SLinus Torvalds if (target) 30951b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 309651892bbbSSage Weil 30971da177e4SLinus Torvalds error = -EBUSY; 309851892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 309951892bbbSSage Weil goto out; 310051892bbbSSage Weil 31011da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 310251892bbbSSage Weil if (error) 310351892bbbSSage Weil goto out; 310451892bbbSSage Weil 3105bec1052eSAl Viro if (target) 3106d83c49f3SAl Viro dont_mount(new_dentry); 3107349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 31081da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 310951892bbbSSage Weil out: 31101da177e4SLinus Torvalds if (target) 31111b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 31121da177e4SLinus Torvalds dput(new_dentry); 31131da177e4SLinus Torvalds return error; 31141da177e4SLinus Torvalds } 31151da177e4SLinus Torvalds 31161da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 31171da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31181da177e4SLinus Torvalds { 31191da177e4SLinus Torvalds int error; 31201da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 312159b0df21SEric Paris const unsigned char *old_name; 31221da177e4SLinus Torvalds 31231da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 31241da177e4SLinus Torvalds return 0; 31251da177e4SLinus Torvalds 31261da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 31271da177e4SLinus Torvalds if (error) 31281da177e4SLinus Torvalds return error; 31291da177e4SLinus Torvalds 31301da177e4SLinus Torvalds if (!new_dentry->d_inode) 3131a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 31321da177e4SLinus Torvalds else 31331da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31341da177e4SLinus Torvalds if (error) 31351da177e4SLinus Torvalds return error; 31361da177e4SLinus Torvalds 3137acfa4380SAl Viro if (!old_dir->i_op->rename) 31381da177e4SLinus Torvalds return -EPERM; 31391da177e4SLinus Torvalds 31400eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31410eeca283SRobert Love 31421da177e4SLinus Torvalds if (is_dir) 31431da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31441da177e4SLinus Torvalds else 31451da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3146123df294SAl Viro if (!error) 3147123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31485a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31490eeca283SRobert Love fsnotify_oldname_free(old_name); 31500eeca283SRobert Love 31511da177e4SLinus Torvalds return error; 31521da177e4SLinus Torvalds } 31531da177e4SLinus Torvalds 31542e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31552e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31561da177e4SLinus Torvalds { 31571da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31581da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31591da177e4SLinus Torvalds struct dentry *trap; 31601da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31612ad94ae6SAl Viro char *from; 31622ad94ae6SAl Viro char *to; 31632ad94ae6SAl Viro int error; 31641da177e4SLinus Torvalds 31652ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31661da177e4SLinus Torvalds if (error) 31671da177e4SLinus Torvalds goto exit; 31681da177e4SLinus Torvalds 31692ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31701da177e4SLinus Torvalds if (error) 31711da177e4SLinus Torvalds goto exit1; 31721da177e4SLinus Torvalds 31731da177e4SLinus Torvalds error = -EXDEV; 31744ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31751da177e4SLinus Torvalds goto exit2; 31761da177e4SLinus Torvalds 31774ac91378SJan Blunck old_dir = oldnd.path.dentry; 31781da177e4SLinus Torvalds error = -EBUSY; 31791da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31801da177e4SLinus Torvalds goto exit2; 31811da177e4SLinus Torvalds 31824ac91378SJan Blunck new_dir = newnd.path.dentry; 31831da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31841da177e4SLinus Torvalds goto exit2; 31851da177e4SLinus Torvalds 31860612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31870612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31884e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31890612d9fbSOGAWA Hirofumi 31901da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31911da177e4SLinus Torvalds 319249705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31931da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31941da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31951da177e4SLinus Torvalds goto exit3; 31961da177e4SLinus Torvalds /* source must exist */ 31971da177e4SLinus Torvalds error = -ENOENT; 31981da177e4SLinus Torvalds if (!old_dentry->d_inode) 31991da177e4SLinus Torvalds goto exit4; 32001da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 32011da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 32021da177e4SLinus Torvalds error = -ENOTDIR; 32031da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 32041da177e4SLinus Torvalds goto exit4; 32051da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 32061da177e4SLinus Torvalds goto exit4; 32071da177e4SLinus Torvalds } 32081da177e4SLinus Torvalds /* source should not be ancestor of target */ 32091da177e4SLinus Torvalds error = -EINVAL; 32101da177e4SLinus Torvalds if (old_dentry == trap) 32111da177e4SLinus Torvalds goto exit4; 321249705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 32131da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 32141da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 32151da177e4SLinus Torvalds goto exit4; 32161da177e4SLinus Torvalds /* target should not be an ancestor of source */ 32171da177e4SLinus Torvalds error = -ENOTEMPTY; 32181da177e4SLinus Torvalds if (new_dentry == trap) 32191da177e4SLinus Torvalds goto exit5; 32201da177e4SLinus Torvalds 32219079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 32229079b1ebSDave Hansen if (error) 32239079b1ebSDave Hansen goto exit5; 3224be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3225be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3226be6d3e56SKentaro Takeda if (error) 3227be6d3e56SKentaro Takeda goto exit6; 32281da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 32291da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3230be6d3e56SKentaro Takeda exit6: 32319079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 32321da177e4SLinus Torvalds exit5: 32331da177e4SLinus Torvalds dput(new_dentry); 32341da177e4SLinus Torvalds exit4: 32351da177e4SLinus Torvalds dput(old_dentry); 32361da177e4SLinus Torvalds exit3: 32371da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32381da177e4SLinus Torvalds exit2: 32391d957f9bSJan Blunck path_put(&newnd.path); 32402ad94ae6SAl Viro putname(to); 32411da177e4SLinus Torvalds exit1: 32421d957f9bSJan Blunck path_put(&oldnd.path); 32431da177e4SLinus Torvalds putname(from); 32442ad94ae6SAl Viro exit: 32451da177e4SLinus Torvalds return error; 32461da177e4SLinus Torvalds } 32471da177e4SLinus Torvalds 3248a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32495590ff0dSUlrich Drepper { 32505590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32515590ff0dSUlrich Drepper } 32525590ff0dSUlrich Drepper 32531da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32541da177e4SLinus Torvalds { 32551da177e4SLinus Torvalds int len; 32561da177e4SLinus Torvalds 32571da177e4SLinus Torvalds len = PTR_ERR(link); 32581da177e4SLinus Torvalds if (IS_ERR(link)) 32591da177e4SLinus Torvalds goto out; 32601da177e4SLinus Torvalds 32611da177e4SLinus Torvalds len = strlen(link); 32621da177e4SLinus Torvalds if (len > (unsigned) buflen) 32631da177e4SLinus Torvalds len = buflen; 32641da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32651da177e4SLinus Torvalds len = -EFAULT; 32661da177e4SLinus Torvalds out: 32671da177e4SLinus Torvalds return len; 32681da177e4SLinus Torvalds } 32691da177e4SLinus Torvalds 32701da177e4SLinus Torvalds /* 32711da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32721da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32731da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32741da177e4SLinus Torvalds */ 32751da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32761da177e4SLinus Torvalds { 32771da177e4SLinus Torvalds struct nameidata nd; 3278cc314eefSLinus Torvalds void *cookie; 3279694a1764SMarcin Slusarz int res; 3280cc314eefSLinus Torvalds 32811da177e4SLinus Torvalds nd.depth = 0; 3282cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3283694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3284694a1764SMarcin Slusarz return PTR_ERR(cookie); 3285694a1764SMarcin Slusarz 3286694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32871da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3288cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3289694a1764SMarcin Slusarz return res; 32901da177e4SLinus Torvalds } 32911da177e4SLinus Torvalds 32921da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32931da177e4SLinus Torvalds { 32941da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32951da177e4SLinus Torvalds } 32961da177e4SLinus Torvalds 32971da177e4SLinus Torvalds /* get the link contents into pagecache */ 32981da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32991da177e4SLinus Torvalds { 3300ebd09abbSDuane Griffin char *kaddr; 33011da177e4SLinus Torvalds struct page *page; 33021da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3303090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 33041da177e4SLinus Torvalds if (IS_ERR(page)) 33056fe6900eSNick Piggin return (char*)page; 33061da177e4SLinus Torvalds *ppage = page; 3307ebd09abbSDuane Griffin kaddr = kmap(page); 3308ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3309ebd09abbSDuane Griffin return kaddr; 33101da177e4SLinus Torvalds } 33111da177e4SLinus Torvalds 33121da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 33131da177e4SLinus Torvalds { 33141da177e4SLinus Torvalds struct page *page = NULL; 33151da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 33161da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 33171da177e4SLinus Torvalds if (page) { 33181da177e4SLinus Torvalds kunmap(page); 33191da177e4SLinus Torvalds page_cache_release(page); 33201da177e4SLinus Torvalds } 33211da177e4SLinus Torvalds return res; 33221da177e4SLinus Torvalds } 33231da177e4SLinus Torvalds 3324cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 33251da177e4SLinus Torvalds { 3326cc314eefSLinus Torvalds struct page *page = NULL; 33271da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3328cc314eefSLinus Torvalds return page; 33291da177e4SLinus Torvalds } 33301da177e4SLinus Torvalds 3331cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 33321da177e4SLinus Torvalds { 3333cc314eefSLinus Torvalds struct page *page = cookie; 3334cc314eefSLinus Torvalds 3335cc314eefSLinus Torvalds if (page) { 33361da177e4SLinus Torvalds kunmap(page); 33371da177e4SLinus Torvalds page_cache_release(page); 33381da177e4SLinus Torvalds } 33391da177e4SLinus Torvalds } 33401da177e4SLinus Torvalds 334154566b2cSNick Piggin /* 334254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 334354566b2cSNick Piggin */ 334454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33451da177e4SLinus Torvalds { 33461da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33470adb25d2SKirill Korotaev struct page *page; 3348afddba49SNick Piggin void *fsdata; 3349beb497abSDmitriy Monakhov int err; 33501da177e4SLinus Torvalds char *kaddr; 335154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 335254566b2cSNick Piggin if (nofs) 335354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33541da177e4SLinus Torvalds 33557e53cac4SNeilBrown retry: 3356afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 335754566b2cSNick Piggin flags, &page, &fsdata); 33581da177e4SLinus Torvalds if (err) 3359afddba49SNick Piggin goto fail; 3360afddba49SNick Piggin 33611da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33621da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33631da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3364afddba49SNick Piggin 3365afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3366afddba49SNick Piggin page, fsdata); 33671da177e4SLinus Torvalds if (err < 0) 33681da177e4SLinus Torvalds goto fail; 3369afddba49SNick Piggin if (err < len-1) 3370afddba49SNick Piggin goto retry; 3371afddba49SNick Piggin 33721da177e4SLinus Torvalds mark_inode_dirty(inode); 33731da177e4SLinus Torvalds return 0; 33741da177e4SLinus Torvalds fail: 33751da177e4SLinus Torvalds return err; 33761da177e4SLinus Torvalds } 33771da177e4SLinus Torvalds 33780adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33790adb25d2SKirill Korotaev { 33800adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 338154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33820adb25d2SKirill Korotaev } 33830adb25d2SKirill Korotaev 338492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33851da177e4SLinus Torvalds .readlink = generic_readlink, 33861da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33871da177e4SLinus Torvalds .put_link = page_put_link, 33881da177e4SLinus Torvalds }; 33891da177e4SLinus Torvalds 33902d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3391cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33921da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33931da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33941da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33951da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33961da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33971da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33981da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33991da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 34001da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 34010adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 34021da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 34031da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3404c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3405d1811465SAl Viro EXPORT_SYMBOL(kern_path); 340616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3407f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 34088c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 34091da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 34101da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 34111da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 34121da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 34131da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 34141da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 34151da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 34161da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 34171da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 34181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 34191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 34201da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 34211da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 34221da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3423