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 { 1825909ccaaSLinus Torvalds umode_t 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. 2411da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2421da177e4SLinus Torvalds */ 243f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 244e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 2451da177e4SLinus Torvalds return 0; 2461da177e4SLinus Torvalds 2471da177e4SLinus Torvalds /* 2481da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2491da177e4SLinus Torvalds */ 2507ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2511da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 252e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 2531da177e4SLinus Torvalds return 0; 2541da177e4SLinus Torvalds 2551da177e4SLinus Torvalds return -EACCES; 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258cb23beb5SChristoph Hellwig /** 259cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 260cb23beb5SChristoph Hellwig * @inode: inode to check permission on 261cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 262cb23beb5SChristoph Hellwig * 263cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 264cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 265cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 266cb23beb5SChristoph Hellwig * are used for other things. 267cb23beb5SChristoph Hellwig */ 268f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2691da177e4SLinus Torvalds { 270e6305c43SAl Viro int retval; 2711da177e4SLinus Torvalds 2721da177e4SLinus Torvalds if (mask & MAY_WRITE) { 27322590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2741da177e4SLinus Torvalds 2751da177e4SLinus Torvalds /* 2761da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2771da177e4SLinus Torvalds */ 2781da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2791da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2801da177e4SLinus Torvalds return -EROFS; 2811da177e4SLinus Torvalds 2821da177e4SLinus Torvalds /* 2831da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2841da177e4SLinus Torvalds */ 2851da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2861da177e4SLinus Torvalds return -EACCES; 2871da177e4SLinus Torvalds } 2881da177e4SLinus Torvalds 289acfa4380SAl Viro if (inode->i_op->permission) 290b74c79e9SNick Piggin retval = inode->i_op->permission(inode, mask, 0); 291f696a365SMiklos Szeredi else 292b74c79e9SNick Piggin retval = generic_permission(inode, mask, 0, 293b74c79e9SNick Piggin inode->i_op->check_acl); 294f696a365SMiklos Szeredi 2951da177e4SLinus Torvalds if (retval) 2961da177e4SLinus Torvalds return retval; 2971da177e4SLinus Torvalds 29808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 29908ce5f16SSerge E. Hallyn if (retval) 30008ce5f16SSerge E. Hallyn return retval; 30108ce5f16SSerge E. Hallyn 302d09ca739SEric Paris return security_inode_permission(inode, mask); 3031da177e4SLinus Torvalds } 3041da177e4SLinus Torvalds 305e4543eddSChristoph Hellwig /** 3068c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 3078c744fb8SChristoph Hellwig * @file: file to check access rights for 3088c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3098c744fb8SChristoph Hellwig * 3108c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3118c744fb8SChristoph Hellwig * file. 3128c744fb8SChristoph Hellwig * 3138c744fb8SChristoph Hellwig * Note: 3148c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 315cb23beb5SChristoph Hellwig * be done using inode_permission(). 3168c744fb8SChristoph Hellwig */ 3178c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3188c744fb8SChristoph Hellwig { 319f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3208c744fb8SChristoph Hellwig } 3218c744fb8SChristoph Hellwig 3221da177e4SLinus Torvalds /* 3231da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3241da177e4SLinus Torvalds * put_write_access() releases this write permission. 3251da177e4SLinus Torvalds * This is used for regular files. 3261da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3271da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3281da177e4SLinus Torvalds * can have the following values: 3291da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3301da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3311da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3321da177e4SLinus Torvalds * 3331da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3341da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3351da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3361da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3371da177e4SLinus Torvalds * the inode->i_lock spinlock. 3381da177e4SLinus Torvalds */ 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3411da177e4SLinus Torvalds { 3421da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3431da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3441da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3451da177e4SLinus Torvalds return -ETXTBSY; 3461da177e4SLinus Torvalds } 3471da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3481da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds return 0; 3511da177e4SLinus Torvalds } 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds int deny_write_access(struct file * file) 3541da177e4SLinus Torvalds { 3550f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3561da177e4SLinus Torvalds 3571da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3581da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3591da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3601da177e4SLinus Torvalds return -ETXTBSY; 3611da177e4SLinus Torvalds } 3621da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3631da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvalds return 0; 3661da177e4SLinus Torvalds } 3671da177e4SLinus Torvalds 3681d957f9bSJan Blunck /** 3695dd784d0SJan Blunck * path_get - get a reference to a path 3705dd784d0SJan Blunck * @path: path to get the reference to 3715dd784d0SJan Blunck * 3725dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3735dd784d0SJan Blunck */ 3745dd784d0SJan Blunck void path_get(struct path *path) 3755dd784d0SJan Blunck { 3765dd784d0SJan Blunck mntget(path->mnt); 3775dd784d0SJan Blunck dget(path->dentry); 3785dd784d0SJan Blunck } 3795dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3805dd784d0SJan Blunck 3815dd784d0SJan Blunck /** 3821d957f9bSJan Blunck * path_put - put a reference to a path 3831d957f9bSJan Blunck * @path: path to put the reference to 3841d957f9bSJan Blunck * 3851d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3861d957f9bSJan Blunck */ 3871d957f9bSJan Blunck void path_put(struct path *path) 3881da177e4SLinus Torvalds { 3891d957f9bSJan Blunck dput(path->dentry); 3901d957f9bSJan Blunck mntput(path->mnt); 3911da177e4SLinus Torvalds } 3921d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3931da177e4SLinus Torvalds 39419660af7SAl Viro /* 39531e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 39619660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 39719660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 39819660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 39919660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 40019660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 40119660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 40219660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 40331e6b01fSNick Piggin */ 40431e6b01fSNick Piggin 40531e6b01fSNick Piggin /** 40619660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 40719660af7SAl Viro * @nd: nameidata pathwalk data 40819660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 40939191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 41031e6b01fSNick Piggin * 41119660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 41219660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 41319660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 41431e6b01fSNick Piggin */ 41519660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 41631e6b01fSNick Piggin { 41731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 41831e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4195b6ca027SAl Viro int want_root = 0; 42031e6b01fSNick Piggin 42131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4225b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4235b6ca027SAl Viro want_root = 1; 42431e6b01fSNick Piggin spin_lock(&fs->lock); 42531e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 42631e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 42731e6b01fSNick Piggin goto err_root; 42831e6b01fSNick Piggin } 42931e6b01fSNick Piggin spin_lock(&parent->d_lock); 43019660af7SAl Viro if (!dentry) { 43119660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 43219660af7SAl Viro goto err_parent; 43319660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 43419660af7SAl Viro } else { 43531e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 43631e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 43719660af7SAl Viro goto err_child; 43831e6b01fSNick Piggin /* 43919660af7SAl Viro * If the sequence check on the child dentry passed, then 44019660af7SAl Viro * the child has not been removed from its parent. This 44119660af7SAl Viro * means the parent dentry must be valid and able to take 44219660af7SAl Viro * a reference at this point. 44331e6b01fSNick Piggin */ 44431e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 44531e6b01fSNick Piggin BUG_ON(!parent->d_count); 44631e6b01fSNick Piggin parent->d_count++; 44731e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 44819660af7SAl Viro } 44931e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4505b6ca027SAl Viro if (want_root) { 45131e6b01fSNick Piggin path_get(&nd->root); 45231e6b01fSNick Piggin spin_unlock(&fs->lock); 45331e6b01fSNick Piggin } 45431e6b01fSNick Piggin mntget(nd->path.mnt); 45531e6b01fSNick Piggin 45631e6b01fSNick Piggin rcu_read_unlock(); 45731e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 45831e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 45931e6b01fSNick Piggin return 0; 46019660af7SAl Viro 46119660af7SAl Viro err_child: 46231e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 46319660af7SAl Viro err_parent: 46431e6b01fSNick Piggin spin_unlock(&parent->d_lock); 46531e6b01fSNick Piggin err_root: 4665b6ca027SAl Viro if (want_root) 46731e6b01fSNick Piggin spin_unlock(&fs->lock); 46831e6b01fSNick Piggin return -ECHILD; 46931e6b01fSNick Piggin } 47031e6b01fSNick Piggin 47131e6b01fSNick Piggin /** 47231e6b01fSNick Piggin * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk 47331e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 47439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 47531e6b01fSNick Piggin * 47631e6b01fSNick Piggin * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. 47731e6b01fSNick Piggin * nd->path should be the final element of the lookup, so nd->root is discarded. 47831e6b01fSNick Piggin * Must be called from rcu-walk context. 47931e6b01fSNick Piggin */ 48031e6b01fSNick Piggin static int nameidata_drop_rcu_last(struct nameidata *nd) 48131e6b01fSNick Piggin { 48231e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 48331e6b01fSNick Piggin 48431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 48531e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 4865b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 48731e6b01fSNick Piggin nd->root.mnt = NULL; 48831e6b01fSNick Piggin spin_lock(&dentry->d_lock); 48931e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 49031e6b01fSNick Piggin goto err_unlock; 49131e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 49231e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 49331e6b01fSNick Piggin 49431e6b01fSNick Piggin mntget(nd->path.mnt); 49531e6b01fSNick Piggin 49631e6b01fSNick Piggin rcu_read_unlock(); 49731e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 49831e6b01fSNick Piggin 49931e6b01fSNick Piggin return 0; 50031e6b01fSNick Piggin 50131e6b01fSNick Piggin err_unlock: 50231e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 50331e6b01fSNick Piggin rcu_read_unlock(); 50431e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 50531e6b01fSNick Piggin return -ECHILD; 50631e6b01fSNick Piggin } 50731e6b01fSNick Piggin 50831e6b01fSNick Piggin /** 509834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 510834f2a4aSTrond Myklebust * @nd: pointer to nameidata 511834f2a4aSTrond Myklebust */ 512834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 513834f2a4aSTrond Myklebust { 5142dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 5152dab5974SLinus Torvalds 5162dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 5172dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 5182dab5974SLinus Torvalds put_filp(file); 519834f2a4aSTrond Myklebust else 5202dab5974SLinus Torvalds fput(file); 5212dab5974SLinus Torvalds } 522834f2a4aSTrond Myklebust } 523834f2a4aSTrond Myklebust 524f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 52534286d66SNick Piggin { 526f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 52734286d66SNick Piggin } 52834286d66SNick Piggin 529f5e1c1c1SAl Viro static struct dentry * 530bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 531bcdc5e01SIan Kent { 532f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 533bcdc5e01SIan Kent if (unlikely(status <= 0)) { 534bcdc5e01SIan Kent /* 535bcdc5e01SIan Kent * The dentry failed validation. 536bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 537bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 538bcdc5e01SIan Kent * to return a fail status. 539bcdc5e01SIan Kent */ 54034286d66SNick Piggin if (status < 0) { 54134286d66SNick Piggin dput(dentry); 54234286d66SNick Piggin dentry = ERR_PTR(status); 543f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 544bcdc5e01SIan Kent dput(dentry); 545bcdc5e01SIan Kent dentry = NULL; 546bcdc5e01SIan Kent } 547bcdc5e01SIan Kent } 548f5e1c1c1SAl Viro return dentry; 549f5e1c1c1SAl Viro } 550f5e1c1c1SAl Viro 5511da177e4SLinus Torvalds /* 55216c2cd71SAl Viro * handle_reval_path - force revalidation of a dentry 55339159de2SJeff Layton * 55439159de2SJeff Layton * In some situations the path walking code will trust dentries without 55539159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 55639159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 55739159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 55839159de2SJeff Layton * a d_revalidate call before proceeding. 55939159de2SJeff Layton * 56039159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 56139159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 56239159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 56339159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 56439159de2SJeff Layton * to the path if necessary. 56539159de2SJeff Layton */ 56616c2cd71SAl Viro static inline int handle_reval_path(struct nameidata *nd) 56739159de2SJeff Layton { 56816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 56939159de2SJeff Layton int status; 57039159de2SJeff Layton 57116c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 57239159de2SJeff Layton return 0; 57339159de2SJeff Layton 57416c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 57516c2cd71SAl Viro return 0; 57616c2cd71SAl Viro 57716c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 57816c2cd71SAl Viro return 0; 57916c2cd71SAl Viro 58016c2cd71SAl Viro /* Note: we do not d_invalidate() */ 58134286d66SNick Piggin status = d_revalidate(dentry, nd); 58239159de2SJeff Layton if (status > 0) 58339159de2SJeff Layton return 0; 58439159de2SJeff Layton 58516c2cd71SAl Viro if (!status) 58639159de2SJeff Layton status = -ESTALE; 58716c2cd71SAl Viro 58839159de2SJeff Layton return status; 58939159de2SJeff Layton } 59039159de2SJeff Layton 59139159de2SJeff Layton /* 592b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 593b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 594b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 5951da177e4SLinus Torvalds * 5961da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 597b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 5981da177e4SLinus Torvalds * complete permission check. 5991da177e4SLinus Torvalds */ 600b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 6011da177e4SLinus Torvalds { 6025909ccaaSLinus Torvalds int ret; 603e795b717SSerge E. Hallyn struct user_namespace *ns = inode_userns(inode); 6041da177e4SLinus Torvalds 605cb9179eaSLinus Torvalds if (inode->i_op->permission) { 606b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 607b74c79e9SNick Piggin } else { 608b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 609b74c79e9SNick Piggin inode->i_op->check_acl); 610cb9179eaSLinus Torvalds } 611b74c79e9SNick Piggin if (likely(!ret)) 6121da177e4SLinus Torvalds goto ok; 613b74c79e9SNick Piggin if (ret == -ECHILD) 61431e6b01fSNick Piggin return ret; 6151da177e4SLinus Torvalds 616e795b717SSerge E. Hallyn if (ns_capable(ns, CAP_DAC_OVERRIDE) || 617e795b717SSerge E. Hallyn ns_capable(ns, CAP_DAC_READ_SEARCH)) 6181da177e4SLinus Torvalds goto ok; 6191da177e4SLinus Torvalds 6205909ccaaSLinus Torvalds return ret; 6211da177e4SLinus Torvalds ok: 622b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 6231da177e4SLinus Torvalds } 6241da177e4SLinus Torvalds 6252a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6262a737871SAl Viro { 627f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 628f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6292a737871SAl Viro } 6302a737871SAl Viro 6316de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6326de88d72SAl Viro 63331e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 63431e6b01fSNick Piggin { 63531e6b01fSNick Piggin if (!nd->root.mnt) { 63631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 637c28cc364SNick Piggin unsigned seq; 638c28cc364SNick Piggin 639c28cc364SNick Piggin do { 640c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 64131e6b01fSNick Piggin nd->root = fs->root; 642c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 643c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 64431e6b01fSNick Piggin } 64531e6b01fSNick Piggin } 64631e6b01fSNick Piggin 647f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6481da177e4SLinus Torvalds { 64931e6b01fSNick Piggin int ret; 65031e6b01fSNick Piggin 6511da177e4SLinus Torvalds if (IS_ERR(link)) 6521da177e4SLinus Torvalds goto fail; 6531da177e4SLinus Torvalds 6541da177e4SLinus Torvalds if (*link == '/') { 6552a737871SAl Viro set_root(nd); 6561d957f9bSJan Blunck path_put(&nd->path); 6572a737871SAl Viro nd->path = nd->root; 6582a737871SAl Viro path_get(&nd->root); 65916c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6601da177e4SLinus Torvalds } 66131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 662b4091d5fSChristoph Hellwig 66331e6b01fSNick Piggin ret = link_path_walk(link, nd); 66431e6b01fSNick Piggin return ret; 6651da177e4SLinus Torvalds fail: 6661d957f9bSJan Blunck path_put(&nd->path); 6671da177e4SLinus Torvalds return PTR_ERR(link); 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds 6701d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 671051d3812SIan Kent { 672051d3812SIan Kent dput(path->dentry); 6734ac91378SJan Blunck if (path->mnt != nd->path.mnt) 674051d3812SIan Kent mntput(path->mnt); 675051d3812SIan Kent } 676051d3812SIan Kent 6777b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6787b9337aaSNick Piggin struct nameidata *nd) 679051d3812SIan Kent { 68031e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6814ac91378SJan Blunck dput(nd->path.dentry); 68231e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6834ac91378SJan Blunck mntput(nd->path.mnt); 6849a229683SHuang Shijie } 68531e6b01fSNick Piggin nd->path.mnt = path->mnt; 6864ac91378SJan Blunck nd->path.dentry = path->dentry; 687051d3812SIan Kent } 688051d3812SIan Kent 689574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 690574197e0SAl Viro { 691574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 692574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 693574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 694574197e0SAl Viro path_put(link); 695574197e0SAl Viro } 696574197e0SAl Viro 697def4af30SAl Viro static __always_inline int 698574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6991da177e4SLinus Torvalds { 7001da177e4SLinus Torvalds int error; 7017b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7021da177e4SLinus Torvalds 703844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 704844a3917SAl Viro 7050e794589SAl Viro if (link->mnt == nd->path.mnt) 7060e794589SAl Viro mntget(link->mnt); 7070e794589SAl Viro 708574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 709574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 710574197e0SAl Viro path_put(&nd->path); 711574197e0SAl Viro return -ELOOP; 712574197e0SAl Viro } 713574197e0SAl Viro cond_resched(); 714574197e0SAl Viro current->total_link_count++; 715574197e0SAl Viro 7167b9337aaSNick Piggin touch_atime(link->mnt, dentry); 7171da177e4SLinus Torvalds nd_set_link(nd, NULL); 718cd4e91d3SAl Viro 71936f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 72036f3b4f6SAl Viro if (error) { 72136f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 72236f3b4f6SAl Viro path_put(&nd->path); 72336f3b4f6SAl Viro return error; 72436f3b4f6SAl Viro } 72536f3b4f6SAl Viro 72686acdca1SAl Viro nd->last_type = LAST_BIND; 727def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 728def4af30SAl Viro error = PTR_ERR(*p); 729def4af30SAl Viro if (!IS_ERR(*p)) { 7301da177e4SLinus Torvalds char *s = nd_get_link(nd); 731cc314eefSLinus Torvalds error = 0; 7321da177e4SLinus Torvalds if (s) 7331da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 734bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 73516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 736b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 737b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 738bcda7652SAl Viro /* stepped on a _really_ weird one */ 739bcda7652SAl Viro path_put(&nd->path); 740bcda7652SAl Viro error = -ELOOP; 741bcda7652SAl Viro } 742bcda7652SAl Viro } 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds return error; 7451da177e4SLinus Torvalds } 7461da177e4SLinus Torvalds 74731e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 74831e6b01fSNick Piggin { 74931e6b01fSNick Piggin struct vfsmount *parent; 75031e6b01fSNick Piggin struct dentry *mountpoint; 75131e6b01fSNick Piggin 75231e6b01fSNick Piggin parent = path->mnt->mnt_parent; 75331e6b01fSNick Piggin if (parent == path->mnt) 75431e6b01fSNick Piggin return 0; 75531e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 75631e6b01fSNick Piggin path->dentry = mountpoint; 75731e6b01fSNick Piggin path->mnt = parent; 75831e6b01fSNick Piggin return 1; 75931e6b01fSNick Piggin } 76031e6b01fSNick Piggin 761bab77ebfSAl Viro int follow_up(struct path *path) 7621da177e4SLinus Torvalds { 7631da177e4SLinus Torvalds struct vfsmount *parent; 7641da177e4SLinus Torvalds struct dentry *mountpoint; 76599b7db7bSNick Piggin 76699b7db7bSNick Piggin br_read_lock(vfsmount_lock); 767bab77ebfSAl Viro parent = path->mnt->mnt_parent; 768bab77ebfSAl Viro if (parent == path->mnt) { 76999b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 7701da177e4SLinus Torvalds return 0; 7711da177e4SLinus Torvalds } 7721da177e4SLinus Torvalds mntget(parent); 773bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 77499b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 775bab77ebfSAl Viro dput(path->dentry); 776bab77ebfSAl Viro path->dentry = mountpoint; 777bab77ebfSAl Viro mntput(path->mnt); 778bab77ebfSAl Viro path->mnt = parent; 7791da177e4SLinus Torvalds return 1; 7801da177e4SLinus Torvalds } 7811da177e4SLinus Torvalds 782b5c84bf6SNick Piggin /* 7839875cf80SDavid Howells * Perform an automount 7849875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7859875cf80SDavid Howells * were called with. 7861da177e4SLinus Torvalds */ 7879875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7889875cf80SDavid Howells bool *need_mntput) 78931e6b01fSNick Piggin { 7909875cf80SDavid Howells struct vfsmount *mnt; 791ea5b778aSDavid Howells int err; 7929875cf80SDavid Howells 7939875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7949875cf80SDavid Howells return -EREMOTE; 7959875cf80SDavid Howells 7966f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 7976f45b656SDavid Howells * and this is the terminal part of the path. 7986f45b656SDavid Howells */ 7996f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 8006f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 8016f45b656SDavid Howells 8029875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 8039875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 8049875cf80SDavid Howells * or wants to open the mounted directory. 8059875cf80SDavid Howells * 8069875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 8079875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 8089875cf80SDavid Howells * appended a '/' to the name. 8099875cf80SDavid Howells */ 8109875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 8119875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 8129875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 8139875cf80SDavid Howells return -EISDIR; 8149875cf80SDavid Howells 8159875cf80SDavid Howells current->total_link_count++; 8169875cf80SDavid Howells if (current->total_link_count >= 40) 8179875cf80SDavid Howells return -ELOOP; 8189875cf80SDavid Howells 8199875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8209875cf80SDavid Howells if (IS_ERR(mnt)) { 8219875cf80SDavid Howells /* 8229875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8239875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 8249875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 8259875cf80SDavid Howells * 8269875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 8279875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 8289875cf80SDavid Howells * the path is inaccessible and we should say so. 8299875cf80SDavid Howells */ 8309875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 8319875cf80SDavid Howells return -EREMOTE; 8329875cf80SDavid Howells return PTR_ERR(mnt); 83331e6b01fSNick Piggin } 834ea5b778aSDavid Howells 8359875cf80SDavid Howells if (!mnt) /* mount collision */ 8369875cf80SDavid Howells return 0; 8379875cf80SDavid Howells 83819a167afSAl Viro err = finish_automount(mnt, path); 839ea5b778aSDavid Howells 840ea5b778aSDavid Howells switch (err) { 841ea5b778aSDavid Howells case -EBUSY: 842ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 84319a167afSAl Viro return 0; 844ea5b778aSDavid Howells case 0: 845463ffb2eSAl Viro dput(path->dentry); 8469875cf80SDavid Howells if (*need_mntput) 8479875cf80SDavid Howells mntput(path->mnt); 8489875cf80SDavid Howells path->mnt = mnt; 8499875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 8509875cf80SDavid Howells *need_mntput = true; 8519875cf80SDavid Howells return 0; 85219a167afSAl Viro default: 85319a167afSAl Viro return err; 8549875cf80SDavid Howells } 85519a167afSAl Viro 856ea5b778aSDavid Howells } 8579875cf80SDavid Howells 8589875cf80SDavid Howells /* 8599875cf80SDavid Howells * Handle a dentry that is managed in some way. 860cc53ce53SDavid Howells * - Flagged for transit management (autofs) 8619875cf80SDavid Howells * - Flagged as mountpoint 8629875cf80SDavid Howells * - Flagged as automount point 8639875cf80SDavid Howells * 8649875cf80SDavid Howells * This may only be called in refwalk mode. 8659875cf80SDavid Howells * 8669875cf80SDavid Howells * Serialization is taken care of in namespace.c 8679875cf80SDavid Howells */ 8689875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 8699875cf80SDavid Howells { 8709875cf80SDavid Howells unsigned managed; 8719875cf80SDavid Howells bool need_mntput = false; 8729875cf80SDavid Howells int ret; 8739875cf80SDavid Howells 8749875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8759875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8769875cf80SDavid Howells * the components of that value change under us */ 8779875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8789875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8799875cf80SDavid Howells unlikely(managed != 0)) { 880cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 881cc53ce53SDavid Howells * being held. */ 882cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 883cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 884cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8851aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 886cc53ce53SDavid Howells if (ret < 0) 887cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 888cc53ce53SDavid Howells } 889cc53ce53SDavid Howells 8909875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8919875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8929875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8939875cf80SDavid Howells if (mounted) { 8949875cf80SDavid Howells dput(path->dentry); 8959875cf80SDavid Howells if (need_mntput) 896463ffb2eSAl Viro mntput(path->mnt); 897463ffb2eSAl Viro path->mnt = mounted; 898463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8999875cf80SDavid Howells need_mntput = true; 9009875cf80SDavid Howells continue; 901463ffb2eSAl Viro } 902463ffb2eSAl Viro 9039875cf80SDavid Howells /* Something is mounted on this dentry in another 9049875cf80SDavid Howells * namespace and/or whatever was mounted there in this 9059875cf80SDavid Howells * namespace got unmounted before we managed to get the 9069875cf80SDavid Howells * vfsmount_lock */ 9071da177e4SLinus Torvalds } 9089875cf80SDavid Howells 9099875cf80SDavid Howells /* Handle an automount point */ 9109875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 9119875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 9129875cf80SDavid Howells if (ret < 0) 9139875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 9149875cf80SDavid Howells continue; 9159875cf80SDavid Howells } 9169875cf80SDavid Howells 9179875cf80SDavid Howells /* We didn't change the current path point */ 9189875cf80SDavid Howells break; 9199875cf80SDavid Howells } 9209875cf80SDavid Howells return 0; 9211da177e4SLinus Torvalds } 9221da177e4SLinus Torvalds 923cc53ce53SDavid Howells int follow_down_one(struct path *path) 9241da177e4SLinus Torvalds { 9251da177e4SLinus Torvalds struct vfsmount *mounted; 9261da177e4SLinus Torvalds 9271c755af4SAl Viro mounted = lookup_mnt(path); 9281da177e4SLinus Torvalds if (mounted) { 9299393bd07SAl Viro dput(path->dentry); 9309393bd07SAl Viro mntput(path->mnt); 9319393bd07SAl Viro path->mnt = mounted; 9329393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9331da177e4SLinus Torvalds return 1; 9341da177e4SLinus Torvalds } 9351da177e4SLinus Torvalds return 0; 9361da177e4SLinus Torvalds } 9371da177e4SLinus Torvalds 93862a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 93962a7375eSIan Kent { 94062a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 94162a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 94262a7375eSIan Kent } 94362a7375eSIan Kent 9449875cf80SDavid Howells /* 9459875cf80SDavid Howells * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we 946cc53ce53SDavid Howells * meet a managed dentry and we're not walking to "..". True is returned to 9479875cf80SDavid Howells * continue, false to abort. 9489875cf80SDavid Howells */ 9499875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 9509875cf80SDavid Howells struct inode **inode, bool reverse_transit) 9519875cf80SDavid Howells { 95262a7375eSIan Kent for (;;) { 9539875cf80SDavid Howells struct vfsmount *mounted; 95462a7375eSIan Kent /* 95562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 95662a7375eSIan Kent * that wants to block transit. 95762a7375eSIan Kent */ 95862a7375eSIan Kent *inode = path->dentry->d_inode; 95962a7375eSIan Kent if (!reverse_transit && 96062a7375eSIan Kent unlikely(managed_dentry_might_block(path->dentry))) 961ab90911fSDavid Howells return false; 96262a7375eSIan Kent 96362a7375eSIan Kent if (!d_mountpoint(path->dentry)) 96462a7375eSIan Kent break; 96562a7375eSIan Kent 9669875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9679875cf80SDavid Howells if (!mounted) 9689875cf80SDavid Howells break; 9699875cf80SDavid Howells path->mnt = mounted; 9709875cf80SDavid Howells path->dentry = mounted->mnt_root; 9719875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 9729875cf80SDavid Howells } 9739875cf80SDavid Howells 9749875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 9759875cf80SDavid Howells return reverse_transit; 9769875cf80SDavid Howells return true; 9779875cf80SDavid Howells } 9789875cf80SDavid Howells 97931e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 98031e6b01fSNick Piggin { 98131e6b01fSNick Piggin struct inode *inode = nd->inode; 98231e6b01fSNick Piggin 98331e6b01fSNick Piggin set_root_rcu(nd); 98431e6b01fSNick Piggin 98531e6b01fSNick Piggin while (1) { 98631e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 98731e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 98831e6b01fSNick Piggin break; 98931e6b01fSNick Piggin } 99031e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 99131e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 99231e6b01fSNick Piggin struct dentry *parent = old->d_parent; 99331e6b01fSNick Piggin unsigned seq; 99431e6b01fSNick Piggin 99531e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 99631e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 997ef7562d5SAl Viro goto failed; 99831e6b01fSNick Piggin inode = parent->d_inode; 99931e6b01fSNick Piggin nd->path.dentry = parent; 100031e6b01fSNick Piggin nd->seq = seq; 100131e6b01fSNick Piggin break; 100231e6b01fSNick Piggin } 100331e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 100431e6b01fSNick Piggin break; 100531e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 100631e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 100731e6b01fSNick Piggin } 10089875cf80SDavid Howells __follow_mount_rcu(nd, &nd->path, &inode, true); 100931e6b01fSNick Piggin nd->inode = inode; 101031e6b01fSNick Piggin return 0; 1011ef7562d5SAl Viro 1012ef7562d5SAl Viro failed: 1013ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 10145b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1015ef7562d5SAl Viro nd->root.mnt = NULL; 1016ef7562d5SAl Viro rcu_read_unlock(); 1017ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 1018ef7562d5SAl Viro return -ECHILD; 101931e6b01fSNick Piggin } 102031e6b01fSNick Piggin 10219875cf80SDavid Howells /* 1022cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1023cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1024cc53ce53SDavid Howells * caller is permitted to proceed or not. 1025cc53ce53SDavid Howells * 1026cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1027cc53ce53SDavid Howells * being true). 1028cc53ce53SDavid Howells */ 10297cc90cc3SAl Viro int follow_down(struct path *path) 1030cc53ce53SDavid Howells { 1031cc53ce53SDavid Howells unsigned managed; 1032cc53ce53SDavid Howells int ret; 1033cc53ce53SDavid Howells 1034cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1035cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1036cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1037cc53ce53SDavid Howells * being held. 1038cc53ce53SDavid Howells * 1039cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1040cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1041cc53ce53SDavid Howells * other than its daemon the right to mount on its 1042cc53ce53SDavid Howells * superstructure. 1043cc53ce53SDavid Howells * 1044cc53ce53SDavid Howells * The filesystem may sleep at this point. 1045cc53ce53SDavid Howells */ 1046cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1047cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1048cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1049ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 10501aed3e42SAl Viro path->dentry, false); 1051cc53ce53SDavid Howells if (ret < 0) 1052cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1053cc53ce53SDavid Howells } 1054cc53ce53SDavid Howells 1055cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1056cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1057cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1058cc53ce53SDavid Howells if (!mounted) 1059cc53ce53SDavid Howells break; 1060cc53ce53SDavid Howells dput(path->dentry); 1061cc53ce53SDavid Howells mntput(path->mnt); 1062cc53ce53SDavid Howells path->mnt = mounted; 1063cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1064cc53ce53SDavid Howells continue; 1065cc53ce53SDavid Howells } 1066cc53ce53SDavid Howells 1067cc53ce53SDavid Howells /* Don't handle automount points here */ 1068cc53ce53SDavid Howells break; 1069cc53ce53SDavid Howells } 1070cc53ce53SDavid Howells return 0; 1071cc53ce53SDavid Howells } 1072cc53ce53SDavid Howells 1073cc53ce53SDavid Howells /* 10749875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10759875cf80SDavid Howells */ 10769875cf80SDavid Howells static void follow_mount(struct path *path) 10779875cf80SDavid Howells { 10789875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10799875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10809875cf80SDavid Howells if (!mounted) 10819875cf80SDavid Howells break; 10829875cf80SDavid Howells dput(path->dentry); 10839875cf80SDavid Howells mntput(path->mnt); 10849875cf80SDavid Howells path->mnt = mounted; 10859875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10869875cf80SDavid Howells } 10879875cf80SDavid Howells } 10889875cf80SDavid Howells 108931e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10901da177e4SLinus Torvalds { 10912a737871SAl Viro set_root(nd); 1092e518ddb7SAndreas Mohr 10931da177e4SLinus Torvalds while(1) { 10944ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10951da177e4SLinus Torvalds 10962a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10972a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10981da177e4SLinus Torvalds break; 10991da177e4SLinus Torvalds } 11004ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11013088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11023088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11031da177e4SLinus Torvalds dput(old); 11041da177e4SLinus Torvalds break; 11051da177e4SLinus Torvalds } 11063088dd70SAl Viro if (!follow_up(&nd->path)) 11071da177e4SLinus Torvalds break; 11081da177e4SLinus Torvalds } 110979ed0226SAl Viro follow_mount(&nd->path); 111031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11111da177e4SLinus Torvalds } 11121da177e4SLinus Torvalds 11131da177e4SLinus Torvalds /* 1114baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1115baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1116baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1117baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1118baa03890SNick Piggin */ 1119baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1120baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1121baa03890SNick Piggin { 1122baa03890SNick Piggin struct inode *inode = parent->d_inode; 1123baa03890SNick Piggin struct dentry *dentry; 1124baa03890SNick Piggin struct dentry *old; 1125baa03890SNick Piggin 1126baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1127baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1128baa03890SNick Piggin return ERR_PTR(-ENOENT); 1129baa03890SNick Piggin 1130baa03890SNick Piggin dentry = d_alloc(parent, name); 1131baa03890SNick Piggin if (unlikely(!dentry)) 1132baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1133baa03890SNick Piggin 1134baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1135baa03890SNick Piggin if (unlikely(old)) { 1136baa03890SNick Piggin dput(dentry); 1137baa03890SNick Piggin dentry = old; 1138baa03890SNick Piggin } 1139baa03890SNick Piggin return dentry; 1140baa03890SNick Piggin } 1141baa03890SNick Piggin 1142baa03890SNick Piggin /* 11431da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11441da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11451da177e4SLinus Torvalds * It _is_ time-critical. 11461da177e4SLinus Torvalds */ 11471da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 114831e6b01fSNick Piggin struct path *path, struct inode **inode) 11491da177e4SLinus Torvalds { 11504ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 115131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11525a18fff2SAl Viro int need_reval = 1; 11535a18fff2SAl Viro int status = 1; 11549875cf80SDavid Howells int err; 11559875cf80SDavid Howells 11563cac260aSAl Viro /* 1157b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1158b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1159b04f784eSNick Piggin * do the non-racy lookup, below. 1160b04f784eSNick Piggin */ 116131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 116231e6b01fSNick Piggin unsigned seq; 116331e6b01fSNick Piggin *inode = nd->inode; 116431e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11655a18fff2SAl Viro if (!dentry) 11665a18fff2SAl Viro goto unlazy; 11675a18fff2SAl Viro 116831e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 116931e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 117031e6b01fSNick Piggin return -ECHILD; 117131e6b01fSNick Piggin nd->seq = seq; 11725a18fff2SAl Viro 117324643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11745a18fff2SAl Viro status = d_revalidate(dentry, nd); 11755a18fff2SAl Viro if (unlikely(status <= 0)) { 11765a18fff2SAl Viro if (status != -ECHILD) 11775a18fff2SAl Viro need_reval = 0; 11785a18fff2SAl Viro goto unlazy; 11795a18fff2SAl Viro } 118024643087SAl Viro } 118131e6b01fSNick Piggin path->mnt = mnt; 118231e6b01fSNick Piggin path->dentry = dentry; 11839875cf80SDavid Howells if (likely(__follow_mount_rcu(nd, path, inode, false))) 11849875cf80SDavid Howells return 0; 11855a18fff2SAl Viro unlazy: 118619660af7SAl Viro if (unlazy_walk(nd, dentry)) 11875a18fff2SAl Viro return -ECHILD; 11885a18fff2SAl Viro } else { 118931e6b01fSNick Piggin dentry = __d_lookup(parent, name); 119024643087SAl Viro } 11915a18fff2SAl Viro 11925a18fff2SAl Viro retry: 11935a18fff2SAl Viro if (unlikely(!dentry)) { 11945a18fff2SAl Viro struct inode *dir = parent->d_inode; 11955a18fff2SAl Viro BUG_ON(nd->inode != dir); 11965a18fff2SAl Viro 11975a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11985a18fff2SAl Viro dentry = d_lookup(parent, name); 11995a18fff2SAl Viro if (likely(!dentry)) { 12005a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 12015a18fff2SAl Viro if (IS_ERR(dentry)) { 12025a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12035a18fff2SAl Viro return PTR_ERR(dentry); 12045a18fff2SAl Viro } 12055a18fff2SAl Viro /* known good */ 12065a18fff2SAl Viro need_reval = 0; 12075a18fff2SAl Viro status = 1; 12085a18fff2SAl Viro } 12095a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12105a18fff2SAl Viro } 12115a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12125a18fff2SAl Viro status = d_revalidate(dentry, nd); 12135a18fff2SAl Viro if (unlikely(status <= 0)) { 12145a18fff2SAl Viro if (status < 0) { 12155a18fff2SAl Viro dput(dentry); 12165a18fff2SAl Viro return status; 12175a18fff2SAl Viro } 12185a18fff2SAl Viro if (!d_invalidate(dentry)) { 12195a18fff2SAl Viro dput(dentry); 12205a18fff2SAl Viro dentry = NULL; 12215a18fff2SAl Viro need_reval = 1; 12225a18fff2SAl Viro goto retry; 12235a18fff2SAl Viro } 12245a18fff2SAl Viro } 12255a18fff2SAl Viro 12261da177e4SLinus Torvalds path->mnt = mnt; 12271da177e4SLinus Torvalds path->dentry = dentry; 12289875cf80SDavid Howells err = follow_managed(path, nd->flags); 122989312214SIan Kent if (unlikely(err < 0)) { 123089312214SIan Kent path_put_conditional(path, nd); 12319875cf80SDavid Howells return err; 123289312214SIan Kent } 123331e6b01fSNick Piggin *inode = path->dentry->d_inode; 12341da177e4SLinus Torvalds return 0; 12351da177e4SLinus Torvalds } 12361da177e4SLinus Torvalds 123752094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 123852094c8aSAl Viro { 123952094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 124052094c8aSAl Viro int err = exec_permission(nd->inode, IPERM_FLAG_RCU); 124152094c8aSAl Viro if (err != -ECHILD) 124252094c8aSAl Viro return err; 124319660af7SAl Viro if (unlazy_walk(nd, NULL)) 124452094c8aSAl Viro return -ECHILD; 124552094c8aSAl Viro } 124652094c8aSAl Viro return exec_permission(nd->inode, 0); 124752094c8aSAl Viro } 124852094c8aSAl Viro 12499856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12509856fa1bSAl Viro { 12519856fa1bSAl Viro if (type == LAST_DOTDOT) { 12529856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12539856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12549856fa1bSAl Viro return -ECHILD; 12559856fa1bSAl Viro } else 12569856fa1bSAl Viro follow_dotdot(nd); 12579856fa1bSAl Viro } 12589856fa1bSAl Viro return 0; 12599856fa1bSAl Viro } 12609856fa1bSAl Viro 1261951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1262951361f9SAl Viro { 1263951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1264951361f9SAl Viro path_put(&nd->path); 1265951361f9SAl Viro } else { 1266951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12675b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1268951361f9SAl Viro nd->root.mnt = NULL; 1269951361f9SAl Viro rcu_read_unlock(); 1270951361f9SAl Viro br_read_unlock(vfsmount_lock); 1271951361f9SAl Viro } 1272951361f9SAl Viro } 1273951361f9SAl Viro 1274ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1275ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1276ce57dfc1SAl Viro { 1277ce57dfc1SAl Viro struct inode *inode; 1278ce57dfc1SAl Viro int err; 1279ce57dfc1SAl Viro /* 1280ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1281ce57dfc1SAl Viro * to be able to know about the current root directory and 1282ce57dfc1SAl Viro * parent relationships. 1283ce57dfc1SAl Viro */ 1284ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1285ce57dfc1SAl Viro return handle_dots(nd, type); 1286ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1287ce57dfc1SAl Viro if (unlikely(err)) { 1288ce57dfc1SAl Viro terminate_walk(nd); 1289ce57dfc1SAl Viro return err; 1290ce57dfc1SAl Viro } 1291ce57dfc1SAl Viro if (!inode) { 1292ce57dfc1SAl Viro path_to_nameidata(path, nd); 1293ce57dfc1SAl Viro terminate_walk(nd); 1294ce57dfc1SAl Viro return -ENOENT; 1295ce57dfc1SAl Viro } 1296ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 129719660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 129819660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 129919660af7SAl Viro terminate_walk(nd); 1300ce57dfc1SAl Viro return -ECHILD; 130119660af7SAl Viro } 130219660af7SAl Viro } 1303ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1304ce57dfc1SAl Viro return 1; 1305ce57dfc1SAl Viro } 1306ce57dfc1SAl Viro path_to_nameidata(path, nd); 1307ce57dfc1SAl Viro nd->inode = inode; 1308ce57dfc1SAl Viro return 0; 1309ce57dfc1SAl Viro } 1310ce57dfc1SAl Viro 13111da177e4SLinus Torvalds /* 1312b356379aSAl Viro * This limits recursive symlink follows to 8, while 1313b356379aSAl Viro * limiting consecutive symlinks to 40. 1314b356379aSAl Viro * 1315b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1316b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1317b356379aSAl Viro */ 1318b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1319b356379aSAl Viro { 1320b356379aSAl Viro int res; 1321b356379aSAl Viro 1322b356379aSAl Viro BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1323b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1324b356379aSAl Viro path_put_conditional(path, nd); 1325b356379aSAl Viro path_put(&nd->path); 1326b356379aSAl Viro return -ELOOP; 1327b356379aSAl Viro } 1328b356379aSAl Viro 1329b356379aSAl Viro nd->depth++; 1330b356379aSAl Viro current->link_count++; 1331b356379aSAl Viro 1332b356379aSAl Viro do { 1333b356379aSAl Viro struct path link = *path; 1334b356379aSAl Viro void *cookie; 1335574197e0SAl Viro 1336574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1337b356379aSAl Viro if (!res) 1338b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1339b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1340574197e0SAl Viro put_link(nd, &link, cookie); 1341b356379aSAl Viro } while (res > 0); 1342b356379aSAl Viro 1343b356379aSAl Viro current->link_count--; 1344b356379aSAl Viro nd->depth--; 1345b356379aSAl Viro return res; 1346b356379aSAl Viro } 1347b356379aSAl Viro 1348b356379aSAl Viro /* 13491da177e4SLinus Torvalds * Name resolution. 1350ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1351ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13521da177e4SLinus Torvalds * 1353ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1354ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13551da177e4SLinus Torvalds */ 13566de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13571da177e4SLinus Torvalds { 13581da177e4SLinus Torvalds struct path next; 13591da177e4SLinus Torvalds int err; 13601da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13611da177e4SLinus Torvalds 13621da177e4SLinus Torvalds while (*name=='/') 13631da177e4SLinus Torvalds name++; 13641da177e4SLinus Torvalds if (!*name) 1365086e183aSAl Viro return 0; 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13681da177e4SLinus Torvalds for(;;) { 13691da177e4SLinus Torvalds unsigned long hash; 13701da177e4SLinus Torvalds struct qstr this; 13711da177e4SLinus Torvalds unsigned int c; 1372fe479a58SAl Viro int type; 13731da177e4SLinus Torvalds 1374cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 137552094c8aSAl Viro 137652094c8aSAl Viro err = may_lookup(nd); 13771da177e4SLinus Torvalds if (err) 13781da177e4SLinus Torvalds break; 13791da177e4SLinus Torvalds 13801da177e4SLinus Torvalds this.name = name; 13811da177e4SLinus Torvalds c = *(const unsigned char *)name; 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds hash = init_name_hash(); 13841da177e4SLinus Torvalds do { 13851da177e4SLinus Torvalds name++; 13861da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13871da177e4SLinus Torvalds c = *(const unsigned char *)name; 13881da177e4SLinus Torvalds } while (c && (c != '/')); 13891da177e4SLinus Torvalds this.len = name - (const char *) this.name; 13901da177e4SLinus Torvalds this.hash = end_name_hash(hash); 13911da177e4SLinus Torvalds 1392fe479a58SAl Viro type = LAST_NORM; 1393fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1394fe479a58SAl Viro case 2: 139516c2cd71SAl Viro if (this.name[1] == '.') { 1396fe479a58SAl Viro type = LAST_DOTDOT; 139716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 139816c2cd71SAl Viro } 1399fe479a58SAl Viro break; 1400fe479a58SAl Viro case 1: 1401fe479a58SAl Viro type = LAST_DOT; 1402fe479a58SAl Viro } 14035a202bcdSAl Viro if (likely(type == LAST_NORM)) { 14045a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 140516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14065a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14075a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14085a202bcdSAl Viro &this); 14095a202bcdSAl Viro if (err < 0) 14105a202bcdSAl Viro break; 14115a202bcdSAl Viro } 14125a202bcdSAl Viro } 1413fe479a58SAl Viro 14141da177e4SLinus Torvalds /* remove trailing slashes? */ 14151da177e4SLinus Torvalds if (!c) 14161da177e4SLinus Torvalds goto last_component; 14171da177e4SLinus Torvalds while (*++name == '/'); 14181da177e4SLinus Torvalds if (!*name) 1419b356379aSAl Viro goto last_component; 14201da177e4SLinus Torvalds 1421ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1422ce57dfc1SAl Viro if (err < 0) 1423ce57dfc1SAl Viro return err; 1424fe479a58SAl Viro 1425ce57dfc1SAl Viro if (err) { 1426b356379aSAl Viro err = nested_symlink(&next, nd); 14271da177e4SLinus Torvalds if (err) 1428a7472babSAl Viro return err; 142931e6b01fSNick Piggin } 14301da177e4SLinus Torvalds err = -ENOTDIR; 143131e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14321da177e4SLinus Torvalds break; 14331da177e4SLinus Torvalds continue; 14341da177e4SLinus Torvalds /* here ends the main loop */ 14351da177e4SLinus Torvalds 14361da177e4SLinus Torvalds last_component: 1437f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1438f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1439ce57dfc1SAl Viro nd->last = this; 1440ce57dfc1SAl Viro nd->last_type = type; 1441ce57dfc1SAl Viro return 0; 1442ce57dfc1SAl Viro } 1443951361f9SAl Viro terminate_walk(nd); 14441da177e4SLinus Torvalds return err; 14451da177e4SLinus Torvalds } 14461da177e4SLinus Torvalds 144770e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 144870e9b357SAl Viro struct nameidata *nd, struct file **fp) 144931e6b01fSNick Piggin { 145031e6b01fSNick Piggin int retval = 0; 145131e6b01fSNick Piggin int fput_needed; 145231e6b01fSNick Piggin struct file *file; 145331e6b01fSNick Piggin 145431e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 145516c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 145631e6b01fSNick Piggin nd->depth = 0; 14575b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14585b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 145973d049a4SAl Viro if (*name) { 14605b6ca027SAl Viro if (!inode->i_op->lookup) 14615b6ca027SAl Viro return -ENOTDIR; 14625b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14635b6ca027SAl Viro if (retval) 14645b6ca027SAl Viro return retval; 146573d049a4SAl Viro } 14665b6ca027SAl Viro nd->path = nd->root; 14675b6ca027SAl Viro nd->inode = inode; 14685b6ca027SAl Viro if (flags & LOOKUP_RCU) { 14695b6ca027SAl Viro br_read_lock(vfsmount_lock); 14705b6ca027SAl Viro rcu_read_lock(); 14715b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 14725b6ca027SAl Viro } else { 14735b6ca027SAl Viro path_get(&nd->path); 14745b6ca027SAl Viro } 14755b6ca027SAl Viro return 0; 14765b6ca027SAl Viro } 14775b6ca027SAl Viro 147831e6b01fSNick Piggin nd->root.mnt = NULL; 147931e6b01fSNick Piggin 148031e6b01fSNick Piggin if (*name=='/') { 1481e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 148231e6b01fSNick Piggin br_read_lock(vfsmount_lock); 148331e6b01fSNick Piggin rcu_read_lock(); 1484e41f7d4eSAl Viro set_root_rcu(nd); 1485e41f7d4eSAl Viro } else { 1486e41f7d4eSAl Viro set_root(nd); 1487e41f7d4eSAl Viro path_get(&nd->root); 1488e41f7d4eSAl Viro } 148931e6b01fSNick Piggin nd->path = nd->root; 149031e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1491e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 149231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1493c28cc364SNick Piggin unsigned seq; 149431e6b01fSNick Piggin 149531e6b01fSNick Piggin br_read_lock(vfsmount_lock); 149631e6b01fSNick Piggin rcu_read_lock(); 149731e6b01fSNick Piggin 1498c28cc364SNick Piggin do { 1499c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 150031e6b01fSNick Piggin nd->path = fs->pwd; 1501c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1502c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1503e41f7d4eSAl Viro } else { 1504e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1505e41f7d4eSAl Viro } 150631e6b01fSNick Piggin } else { 150731e6b01fSNick Piggin struct dentry *dentry; 150831e6b01fSNick Piggin 15091abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 151031e6b01fSNick Piggin retval = -EBADF; 151131e6b01fSNick Piggin if (!file) 151231e6b01fSNick Piggin goto out_fail; 151331e6b01fSNick Piggin 151431e6b01fSNick Piggin dentry = file->f_path.dentry; 151531e6b01fSNick Piggin 1516f52e0c11SAl Viro if (*name) { 151731e6b01fSNick Piggin retval = -ENOTDIR; 151831e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 151931e6b01fSNick Piggin goto fput_fail; 152031e6b01fSNick Piggin 152131e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 152231e6b01fSNick Piggin if (retval) 152331e6b01fSNick Piggin goto fput_fail; 1524f52e0c11SAl Viro } 152531e6b01fSNick Piggin 152631e6b01fSNick Piggin nd->path = file->f_path; 1527e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 152831e6b01fSNick Piggin if (fput_needed) 152970e9b357SAl Viro *fp = file; 1530c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 153131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 153231e6b01fSNick Piggin rcu_read_lock(); 15335590ff0dSUlrich Drepper } else { 15345dd784d0SJan Blunck path_get(&file->f_path); 15355590ff0dSUlrich Drepper fput_light(file, fput_needed); 15361da177e4SLinus Torvalds } 1537e41f7d4eSAl Viro } 1538e41f7d4eSAl Viro 153931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15409b4a9b14SAl Viro return 0; 15412dfdd266SJosef 'Jeff' Sipek 15429b4a9b14SAl Viro fput_fail: 15439b4a9b14SAl Viro fput_light(file, fput_needed); 15449b4a9b14SAl Viro out_fail: 15459b4a9b14SAl Viro return retval; 15469b4a9b14SAl Viro } 15479b4a9b14SAl Viro 1548bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1549bd92d7feSAl Viro { 1550bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1551bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1552bd92d7feSAl Viro 1553bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1554bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1555bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1556bd92d7feSAl Viro } 1557bd92d7feSAl Viro 15589b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1559ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15609b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15619b4a9b14SAl Viro { 156270e9b357SAl Viro struct file *base = NULL; 1563bd92d7feSAl Viro struct path path; 1564bd92d7feSAl Viro int err; 156531e6b01fSNick Piggin 156631e6b01fSNick Piggin /* 156731e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 156831e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 156931e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 157031e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 157131e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 157231e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 157331e6b01fSNick Piggin * analogue, foo_rcu(). 157431e6b01fSNick Piggin * 157531e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 157631e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 157731e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 157831e6b01fSNick Piggin * be able to complete). 157931e6b01fSNick Piggin */ 1580bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1581ee0827cdSAl Viro 1582bd92d7feSAl Viro if (unlikely(err)) 1583bd92d7feSAl Viro return err; 1584ee0827cdSAl Viro 1585ee0827cdSAl Viro current->total_link_count = 0; 1586bd92d7feSAl Viro err = link_path_walk(name, nd); 1587bd92d7feSAl Viro 1588bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1589bd92d7feSAl Viro err = lookup_last(nd, &path); 1590bd92d7feSAl Viro while (err > 0) { 1591bd92d7feSAl Viro void *cookie; 1592bd92d7feSAl Viro struct path link = path; 1593bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1594574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1595bd92d7feSAl Viro if (!err) 1596bd92d7feSAl Viro err = lookup_last(nd, &path); 1597574197e0SAl Viro put_link(nd, &link, cookie); 1598bd92d7feSAl Viro } 1599bd92d7feSAl Viro } 1600ee0827cdSAl Viro 1601ee0827cdSAl Viro if (nd->flags & LOOKUP_RCU) { 16024455ca62SAl Viro /* went all way through without dropping RCU */ 1603bd92d7feSAl Viro BUG_ON(err); 1604086e183aSAl Viro if (nameidata_drop_rcu_last(nd)) 1605bd92d7feSAl Viro err = -ECHILD; 1606086e183aSAl Viro } 160731e6b01fSNick Piggin 1608bd23a539SAl Viro if (!err) { 1609bd92d7feSAl Viro err = handle_reval_path(nd); 1610bd23a539SAl Viro if (err) 1611bd23a539SAl Viro path_put(&nd->path); 1612bd23a539SAl Viro } 1613bd92d7feSAl Viro 1614bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1615bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1616bd92d7feSAl Viro path_put(&nd->path); 1617bd23a539SAl Viro err = -ENOTDIR; 1618bd92d7feSAl Viro } 1619bd92d7feSAl Viro } 162016c2cd71SAl Viro 162170e9b357SAl Viro if (base) 162270e9b357SAl Viro fput(base); 1623ee0827cdSAl Viro 16245b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 162531e6b01fSNick Piggin path_put(&nd->root); 162631e6b01fSNick Piggin nd->root.mnt = NULL; 162731e6b01fSNick Piggin } 1628bd92d7feSAl Viro return err; 162931e6b01fSNick Piggin } 163031e6b01fSNick Piggin 1631ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1632ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1633ee0827cdSAl Viro { 1634ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1635ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1636ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1637ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1638ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1639ee0827cdSAl Viro 164031e6b01fSNick Piggin if (likely(!retval)) { 164131e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 164231e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 164331e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 164431e6b01fSNick Piggin } 164531e6b01fSNick Piggin } 1646170aa3d0SUlrich Drepper return retval; 16471da177e4SLinus Torvalds } 16481da177e4SLinus Torvalds 1649c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16505590ff0dSUlrich Drepper { 1651c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16525590ff0dSUlrich Drepper } 16535590ff0dSUlrich Drepper 1654d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1655d1811465SAl Viro { 1656d1811465SAl Viro struct nameidata nd; 1657d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1658d1811465SAl Viro if (!res) 1659d1811465SAl Viro *path = nd.path; 1660d1811465SAl Viro return res; 1661d1811465SAl Viro } 1662d1811465SAl Viro 166316f18200SJosef 'Jeff' Sipek /** 166416f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 166516f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 166616f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 166716f18200SJosef 'Jeff' Sipek * @name: pointer to file name 166816f18200SJosef 'Jeff' Sipek * @flags: lookup flags 166916f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 167016f18200SJosef 'Jeff' Sipek */ 167116f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 167216f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 167316f18200SJosef 'Jeff' Sipek struct nameidata *nd) 167416f18200SJosef 'Jeff' Sipek { 16755b6ca027SAl Viro nd->root.dentry = dentry; 16765b6ca027SAl Viro nd->root.mnt = mnt; 16775b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 16785b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 167916f18200SJosef 'Jeff' Sipek } 168016f18200SJosef 'Jeff' Sipek 1681eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1682eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16831da177e4SLinus Torvalds { 168481fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16851da177e4SLinus Torvalds struct dentry *dentry; 16861da177e4SLinus Torvalds int err; 16871da177e4SLinus Torvalds 1688b74c79e9SNick Piggin err = exec_permission(inode, 0); 168981fca444SChristoph Hellwig if (err) 169081fca444SChristoph Hellwig return ERR_PTR(err); 16911da177e4SLinus Torvalds 16921da177e4SLinus Torvalds /* 1693b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1694b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1695b04f784eSNick Piggin * a double lookup. 16966e6b1bd1SAl Viro */ 16976e6b1bd1SAl Viro dentry = d_lookup(base, name); 16986e6b1bd1SAl Viro 1699fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 17006e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 17016e6b1bd1SAl Viro 17021da177e4SLinus Torvalds if (!dentry) 1703baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17045a202bcdSAl Viro 17051da177e4SLinus Torvalds return dentry; 17061da177e4SLinus Torvalds } 17071da177e4SLinus Torvalds 1708057f6c01SJames Morris /* 1709057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1710057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1711057f6c01SJames Morris * SMP-safe. 1712057f6c01SJames Morris */ 1713a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17141da177e4SLinus Torvalds { 17154ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17161da177e4SLinus Torvalds } 17171da177e4SLinus Torvalds 1718eead1911SChristoph Hellwig /** 1719a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1720eead1911SChristoph Hellwig * @name: pathname component to lookup 1721eead1911SChristoph Hellwig * @base: base directory to lookup from 1722eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1723eead1911SChristoph Hellwig * 1724a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1725a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1726eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1727eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1728eead1911SChristoph Hellwig */ 1729057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1730057f6c01SJames Morris { 1731057f6c01SJames Morris struct qstr this; 17326a96ba54SAl Viro unsigned long hash; 17336a96ba54SAl Viro unsigned int c; 1734057f6c01SJames Morris 17352f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17362f9092e1SDavid Woodhouse 17376a96ba54SAl Viro this.name = name; 17386a96ba54SAl Viro this.len = len; 17396a96ba54SAl Viro if (!len) 17406a96ba54SAl Viro return ERR_PTR(-EACCES); 17416a96ba54SAl Viro 17426a96ba54SAl Viro hash = init_name_hash(); 17436a96ba54SAl Viro while (len--) { 17446a96ba54SAl Viro c = *(const unsigned char *)name++; 17456a96ba54SAl Viro if (c == '/' || c == '\0') 17466a96ba54SAl Viro return ERR_PTR(-EACCES); 17476a96ba54SAl Viro hash = partial_name_hash(c, hash); 17486a96ba54SAl Viro } 17496a96ba54SAl Viro this.hash = end_name_hash(hash); 17505a202bcdSAl Viro /* 17515a202bcdSAl Viro * See if the low-level filesystem might want 17525a202bcdSAl Viro * to use its own hash.. 17535a202bcdSAl Viro */ 17545a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17555a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17565a202bcdSAl Viro if (err < 0) 17575a202bcdSAl Viro return ERR_PTR(err); 17585a202bcdSAl Viro } 1759eead1911SChristoph Hellwig 176049705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1761057f6c01SJames Morris } 1762057f6c01SJames Morris 17632d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 17642d8f3038SAl Viro struct path *path) 17651da177e4SLinus Torvalds { 17662d8f3038SAl Viro struct nameidata nd; 1767f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 17681da177e4SLinus Torvalds int err = PTR_ERR(tmp); 17691da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 17702d8f3038SAl Viro 17712d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 17722d8f3038SAl Viro 17732d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 17741da177e4SLinus Torvalds putname(tmp); 17752d8f3038SAl Viro if (!err) 17762d8f3038SAl Viro *path = nd.path; 17771da177e4SLinus Torvalds } 17781da177e4SLinus Torvalds return err; 17791da177e4SLinus Torvalds } 17801da177e4SLinus Torvalds 17812ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 17822ad94ae6SAl Viro struct nameidata *nd, char **name) 17832ad94ae6SAl Viro { 17842ad94ae6SAl Viro char *s = getname(path); 17852ad94ae6SAl Viro int error; 17862ad94ae6SAl Viro 17872ad94ae6SAl Viro if (IS_ERR(s)) 17882ad94ae6SAl Viro return PTR_ERR(s); 17892ad94ae6SAl Viro 17902ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 17912ad94ae6SAl Viro if (error) 17922ad94ae6SAl Viro putname(s); 17932ad94ae6SAl Viro else 17942ad94ae6SAl Viro *name = s; 17952ad94ae6SAl Viro 17962ad94ae6SAl Viro return error; 17972ad94ae6SAl Viro } 17982ad94ae6SAl Viro 17991da177e4SLinus Torvalds /* 18001da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18011da177e4SLinus Torvalds * minimal. 18021da177e4SLinus Torvalds */ 18031da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18041da177e4SLinus Torvalds { 1805da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1806da9592edSDavid Howells 18071da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18081da177e4SLinus Torvalds return 0; 1809e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1810e795b717SSerge E. Hallyn goto other_userns; 1811da9592edSDavid Howells if (inode->i_uid == fsuid) 18121da177e4SLinus Torvalds return 0; 1813da9592edSDavid Howells if (dir->i_uid == fsuid) 18141da177e4SLinus Torvalds return 0; 1815e795b717SSerge E. Hallyn 1816e795b717SSerge E. Hallyn other_userns: 1817e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 18181da177e4SLinus Torvalds } 18191da177e4SLinus Torvalds 18201da177e4SLinus Torvalds /* 18211da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18221da177e4SLinus Torvalds * whether the type of victim is right. 18231da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18241da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18251da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18261da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18271da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18281da177e4SLinus Torvalds * a. be owner of dir, or 18291da177e4SLinus Torvalds * b. be owner of victim, or 18301da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18311da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18321da177e4SLinus Torvalds * links pointing to it. 18331da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18341da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18351da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18361da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18371da177e4SLinus Torvalds * nfs_async_unlink(). 18381da177e4SLinus Torvalds */ 1839858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18401da177e4SLinus Torvalds { 18411da177e4SLinus Torvalds int error; 18421da177e4SLinus Torvalds 18431da177e4SLinus Torvalds if (!victim->d_inode) 18441da177e4SLinus Torvalds return -ENOENT; 18451da177e4SLinus Torvalds 18461da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1847cccc6bbaSAl Viro audit_inode_child(victim, dir); 18481da177e4SLinus Torvalds 1849f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18501da177e4SLinus Torvalds if (error) 18511da177e4SLinus Torvalds return error; 18521da177e4SLinus Torvalds if (IS_APPEND(dir)) 18531da177e4SLinus Torvalds return -EPERM; 18541da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1855f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18561da177e4SLinus Torvalds return -EPERM; 18571da177e4SLinus Torvalds if (isdir) { 18581da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18591da177e4SLinus Torvalds return -ENOTDIR; 18601da177e4SLinus Torvalds if (IS_ROOT(victim)) 18611da177e4SLinus Torvalds return -EBUSY; 18621da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18631da177e4SLinus Torvalds return -EISDIR; 18641da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18651da177e4SLinus Torvalds return -ENOENT; 18661da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 18671da177e4SLinus Torvalds return -EBUSY; 18681da177e4SLinus Torvalds return 0; 18691da177e4SLinus Torvalds } 18701da177e4SLinus Torvalds 18711da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 18721da177e4SLinus Torvalds * dir. 18731da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 18741da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 18751da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 18761da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 18771da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 18781da177e4SLinus Torvalds */ 1879a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 18801da177e4SLinus Torvalds { 18811da177e4SLinus Torvalds if (child->d_inode) 18821da177e4SLinus Torvalds return -EEXIST; 18831da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18841da177e4SLinus Torvalds return -ENOENT; 1885f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 18861da177e4SLinus Torvalds } 18871da177e4SLinus Torvalds 18881da177e4SLinus Torvalds /* 18891da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 18901da177e4SLinus Torvalds */ 18911da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 18921da177e4SLinus Torvalds { 18931da177e4SLinus Torvalds struct dentry *p; 18941da177e4SLinus Torvalds 18951da177e4SLinus Torvalds if (p1 == p2) { 1896f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 18971da177e4SLinus Torvalds return NULL; 18981da177e4SLinus Torvalds } 18991da177e4SLinus Torvalds 1900a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19011da177e4SLinus Torvalds 1902e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1903e2761a11SOGAWA Hirofumi if (p) { 1904f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1905f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19061da177e4SLinus Torvalds return p; 19071da177e4SLinus Torvalds } 19081da177e4SLinus Torvalds 1909e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1910e2761a11SOGAWA Hirofumi if (p) { 1911f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1912f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19131da177e4SLinus Torvalds return p; 19141da177e4SLinus Torvalds } 19151da177e4SLinus Torvalds 1916f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1917f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19181da177e4SLinus Torvalds return NULL; 19191da177e4SLinus Torvalds } 19201da177e4SLinus Torvalds 19211da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19221da177e4SLinus Torvalds { 19231b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19241da177e4SLinus Torvalds if (p1 != p2) { 19251b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1926a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19271da177e4SLinus Torvalds } 19281da177e4SLinus Torvalds } 19291da177e4SLinus Torvalds 19301da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19311da177e4SLinus Torvalds struct nameidata *nd) 19321da177e4SLinus Torvalds { 1933a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19341da177e4SLinus Torvalds 19351da177e4SLinus Torvalds if (error) 19361da177e4SLinus Torvalds return error; 19371da177e4SLinus Torvalds 1938acfa4380SAl Viro if (!dir->i_op->create) 19391da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19401da177e4SLinus Torvalds mode &= S_IALLUGO; 19411da177e4SLinus Torvalds mode |= S_IFREG; 19421da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19431da177e4SLinus Torvalds if (error) 19441da177e4SLinus Torvalds return error; 19451da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1946a74574aaSStephen Smalley if (!error) 1947f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19481da177e4SLinus Torvalds return error; 19491da177e4SLinus Torvalds } 19501da177e4SLinus Torvalds 195173d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19521da177e4SLinus Torvalds { 19533fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19541da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19551da177e4SLinus Torvalds int error; 19561da177e4SLinus Torvalds 1957bcda7652SAl Viro /* O_PATH? */ 1958bcda7652SAl Viro if (!acc_mode) 1959bcda7652SAl Viro return 0; 1960bcda7652SAl Viro 19611da177e4SLinus Torvalds if (!inode) 19621da177e4SLinus Torvalds return -ENOENT; 19631da177e4SLinus Torvalds 1964c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1965c8fe8f30SChristoph Hellwig case S_IFLNK: 19661da177e4SLinus Torvalds return -ELOOP; 1967c8fe8f30SChristoph Hellwig case S_IFDIR: 1968c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 19691da177e4SLinus Torvalds return -EISDIR; 1970c8fe8f30SChristoph Hellwig break; 1971c8fe8f30SChristoph Hellwig case S_IFBLK: 1972c8fe8f30SChristoph Hellwig case S_IFCHR: 19733fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 19741da177e4SLinus Torvalds return -EACCES; 1975c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1976c8fe8f30SChristoph Hellwig case S_IFIFO: 1977c8fe8f30SChristoph Hellwig case S_IFSOCK: 19781da177e4SLinus Torvalds flag &= ~O_TRUNC; 1979c8fe8f30SChristoph Hellwig break; 19804a3fd211SDave Hansen } 1981b41572e9SDave Hansen 19823fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1983b41572e9SDave Hansen if (error) 1984b41572e9SDave Hansen return error; 19856146f0d5SMimi Zohar 19861da177e4SLinus Torvalds /* 19871da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 19881da177e4SLinus Torvalds */ 19891da177e4SLinus Torvalds if (IS_APPEND(inode)) { 19908737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 19917715b521SAl Viro return -EPERM; 19921da177e4SLinus Torvalds if (flag & O_TRUNC) 19937715b521SAl Viro return -EPERM; 19941da177e4SLinus Torvalds } 19951da177e4SLinus Torvalds 19961da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 19972e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 19987715b521SAl Viro return -EPERM; 19991da177e4SLinus Torvalds 20001da177e4SLinus Torvalds /* 20011da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 20021da177e4SLinus Torvalds */ 2003b65a9cfcSAl Viro return break_lease(inode, flag); 20047715b521SAl Viro } 20057715b521SAl Viro 2006e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20077715b521SAl Viro { 2008e1181ee6SJeff Layton struct path *path = &filp->f_path; 20097715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20107715b521SAl Viro int error = get_write_access(inode); 20111da177e4SLinus Torvalds if (error) 20127715b521SAl Viro return error; 20131da177e4SLinus Torvalds /* 20141da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20151da177e4SLinus Torvalds */ 20161da177e4SLinus Torvalds error = locks_verify_locked(inode); 2017be6d3e56SKentaro Takeda if (!error) 2018ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20191da177e4SLinus Torvalds if (!error) { 20207715b521SAl Viro error = do_truncate(path->dentry, 0, 2021d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2022e1181ee6SJeff Layton filp); 20231da177e4SLinus Torvalds } 20241da177e4SLinus Torvalds put_write_access(inode); 2025acd0c935SMimi Zohar return error; 20261da177e4SLinus Torvalds } 20271da177e4SLinus Torvalds 2028d57999e1SDave Hansen /* 2029d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2030d57999e1SDave Hansen * 00 - read-only 2031d57999e1SDave Hansen * 01 - write-only 2032d57999e1SDave Hansen * 10 - read-write 2033d57999e1SDave Hansen * 11 - special 2034d57999e1SDave Hansen * it is changed into 2035d57999e1SDave Hansen * 00 - no permissions needed 2036d57999e1SDave Hansen * 01 - read-permission 2037d57999e1SDave Hansen * 10 - write-permission 2038d57999e1SDave Hansen * 11 - read-write 2039d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2040d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2041d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2042d57999e1SDave Hansen * later). 2043d57999e1SDave Hansen * 2044d57999e1SDave Hansen */ 2045d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2046d57999e1SDave Hansen { 2047d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2048d57999e1SDave Hansen flag++; 2049d57999e1SDave Hansen return flag; 2050d57999e1SDave Hansen } 2051d57999e1SDave Hansen 205231e6b01fSNick Piggin /* 2053fe2d35ffSAl Viro * Handle the last step of open() 205431e6b01fSNick Piggin */ 2055fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2056c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2057fb1cc555SAl Viro { 2058a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20596c0d46c4SAl Viro struct dentry *dentry; 2060ca344a89SAl Viro int open_flag = op->open_flag; 20616c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2062ca344a89SAl Viro int want_write = 0; 2063bcda7652SAl Viro int acc_mode = op->acc_mode; 2064fb1cc555SAl Viro struct file *filp; 206516c2cd71SAl Viro int error; 2066fb1cc555SAl Viro 2067c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2068c3e380b0SAl Viro nd->flags |= op->intent; 2069c3e380b0SAl Viro 20701f36f774SAl Viro switch (nd->last_type) { 20711f36f774SAl Viro case LAST_DOTDOT: 2072176306f5SNeil Brown case LAST_DOT: 2073fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2074fe2d35ffSAl Viro if (error) 2075fe2d35ffSAl Viro return ERR_PTR(error); 20761f36f774SAl Viro /* fallthrough */ 20771f36f774SAl Viro case LAST_ROOT: 2078fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2079fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2080fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2081fe2d35ffSAl Viro } 208216c2cd71SAl Viro error = handle_reval_path(nd); 208316c2cd71SAl Viro if (error) 208416c2cd71SAl Viro goto exit; 2085fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2086ca344a89SAl Viro if (open_flag & O_CREAT) { 208716c2cd71SAl Viro error = -EISDIR; 20881f36f774SAl Viro goto exit; 2089fe2d35ffSAl Viro } 2090fe2d35ffSAl Viro goto ok; 20911f36f774SAl Viro case LAST_BIND: 2092fe2d35ffSAl Viro /* can't be RCU mode here */ 209316c2cd71SAl Viro error = handle_reval_path(nd); 209416c2cd71SAl Viro if (error) 209516c2cd71SAl Viro goto exit; 20961f36f774SAl Viro audit_inode(pathname, dir); 20971f36f774SAl Viro goto ok; 20981f36f774SAl Viro } 2099a2c36b45SAl Viro 2100ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2101bcda7652SAl Viro int symlink_ok = 0; 2102fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2103fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2104bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2105bcda7652SAl Viro symlink_ok = 1; 2106fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2107ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2108ce57dfc1SAl Viro !symlink_ok); 2109ce57dfc1SAl Viro if (error < 0) 2110fe2d35ffSAl Viro return ERR_PTR(error); 2111ce57dfc1SAl Viro if (error) /* symlink */ 2112fe2d35ffSAl Viro return NULL; 2113fe2d35ffSAl Viro /* sayonara */ 2114fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2115fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2116fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2117fe2d35ffSAl Viro } 2118fe2d35ffSAl Viro 2119fe2d35ffSAl Viro error = -ENOTDIR; 2120fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2121ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2122fe2d35ffSAl Viro goto exit; 2123fe2d35ffSAl Viro } 2124fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2125fe2d35ffSAl Viro goto ok; 2126fe2d35ffSAl Viro } 2127fe2d35ffSAl Viro 2128fe2d35ffSAl Viro /* create side of things */ 2129fe2d35ffSAl Viro 2130fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2131fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2132fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2133fe2d35ffSAl Viro } 2134fe2d35ffSAl Viro 2135fe2d35ffSAl Viro audit_inode(pathname, dir); 213616c2cd71SAl Viro error = -EISDIR; 21371f36f774SAl Viro /* trailing slashes? */ 213831e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21391f36f774SAl Viro goto exit; 21401f36f774SAl Viro 2141a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2142a1e28038SAl Viro 21436c0d46c4SAl Viro dentry = lookup_hash(nd); 21446c0d46c4SAl Viro error = PTR_ERR(dentry); 21456c0d46c4SAl Viro if (IS_ERR(dentry)) { 2146fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2147fb1cc555SAl Viro goto exit; 2148fb1cc555SAl Viro } 2149fb1cc555SAl Viro 21506c0d46c4SAl Viro path->dentry = dentry; 21516c0d46c4SAl Viro path->mnt = nd->path.mnt; 21526c0d46c4SAl Viro 2153fb1cc555SAl Viro /* Negative dentry, just create the file */ 21546c0d46c4SAl Viro if (!dentry->d_inode) { 21556c0d46c4SAl Viro int mode = op->mode; 21566c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21576c0d46c4SAl Viro mode &= ~current_umask(); 2158fb1cc555SAl Viro /* 2159fb1cc555SAl Viro * This write is needed to ensure that a 21606c0d46c4SAl Viro * rw->ro transition does not occur between 2161fb1cc555SAl Viro * the time when the file is created and when 2162fb1cc555SAl Viro * a permanent write count is taken through 2163fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2164fb1cc555SAl Viro */ 2165fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2166fb1cc555SAl Viro if (error) 2167fb1cc555SAl Viro goto exit_mutex_unlock; 2168ca344a89SAl Viro want_write = 1; 21699b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2170ca344a89SAl Viro open_flag &= ~O_TRUNC; 21716c0d46c4SAl Viro will_truncate = 0; 2172bcda7652SAl Viro acc_mode = MAY_OPEN; 21736c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 21746c0d46c4SAl Viro if (error) 21756c0d46c4SAl Viro goto exit_mutex_unlock; 21766c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 21776c0d46c4SAl Viro if (error) 21786c0d46c4SAl Viro goto exit_mutex_unlock; 21796c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 21806c0d46c4SAl Viro dput(nd->path.dentry); 21816c0d46c4SAl Viro nd->path.dentry = dentry; 2182ca344a89SAl Viro goto common; 2183fb1cc555SAl Viro } 2184fb1cc555SAl Viro 2185fb1cc555SAl Viro /* 2186fb1cc555SAl Viro * It already exists. 2187fb1cc555SAl Viro */ 2188fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2189fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2190fb1cc555SAl Viro 2191fb1cc555SAl Viro error = -EEXIST; 2192ca344a89SAl Viro if (open_flag & O_EXCL) 2193fb1cc555SAl Viro goto exit_dput; 2194fb1cc555SAl Viro 21959875cf80SDavid Howells error = follow_managed(path, nd->flags); 21969875cf80SDavid Howells if (error < 0) 2197fb1cc555SAl Viro goto exit_dput; 2198fb1cc555SAl Viro 2199fb1cc555SAl Viro error = -ENOENT; 2200fb1cc555SAl Viro if (!path->dentry->d_inode) 2201fb1cc555SAl Viro goto exit_dput; 22029e67f361SAl Viro 22039e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2204fb1cc555SAl Viro return NULL; 2205fb1cc555SAl Viro 2206fb1cc555SAl Viro path_to_nameidata(path, nd); 220731e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2208fb1cc555SAl Viro error = -EISDIR; 220931e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2210fb1cc555SAl Viro goto exit; 221167ee3ad2SAl Viro ok: 22126c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22136c0d46c4SAl Viro will_truncate = 0; 22146c0d46c4SAl Viro 22150f9d1a10SAl Viro if (will_truncate) { 22160f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22170f9d1a10SAl Viro if (error) 22180f9d1a10SAl Viro goto exit; 2219ca344a89SAl Viro want_write = 1; 22200f9d1a10SAl Viro } 2221ca344a89SAl Viro common: 2222bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2223ca344a89SAl Viro if (error) 22240f9d1a10SAl Viro goto exit; 22250f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22260f9d1a10SAl Viro if (!IS_ERR(filp)) { 22270f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22280f9d1a10SAl Viro if (error) { 22290f9d1a10SAl Viro fput(filp); 22300f9d1a10SAl Viro filp = ERR_PTR(error); 22310f9d1a10SAl Viro } 22320f9d1a10SAl Viro } 22330f9d1a10SAl Viro if (!IS_ERR(filp)) { 22340f9d1a10SAl Viro if (will_truncate) { 22350f9d1a10SAl Viro error = handle_truncate(filp); 22360f9d1a10SAl Viro if (error) { 22370f9d1a10SAl Viro fput(filp); 22380f9d1a10SAl Viro filp = ERR_PTR(error); 22390f9d1a10SAl Viro } 22400f9d1a10SAl Viro } 22410f9d1a10SAl Viro } 2242ca344a89SAl Viro out: 2243ca344a89SAl Viro if (want_write) 22440f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22450f9d1a10SAl Viro path_put(&nd->path); 2246fb1cc555SAl Viro return filp; 2247fb1cc555SAl Viro 2248fb1cc555SAl Viro exit_mutex_unlock: 2249fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2250fb1cc555SAl Viro exit_dput: 2251fb1cc555SAl Viro path_put_conditional(path, nd); 2252fb1cc555SAl Viro exit: 2253ca344a89SAl Viro filp = ERR_PTR(error); 2254ca344a89SAl Viro goto out; 2255fb1cc555SAl Viro } 2256fb1cc555SAl Viro 225713aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 225873d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22591da177e4SLinus Torvalds { 2260fe2d35ffSAl Viro struct file *base = NULL; 22614a3fd211SDave Hansen struct file *filp; 22629850c056SAl Viro struct path path; 226313aab428SAl Viro int error; 226431e6b01fSNick Piggin 226531e6b01fSNick Piggin filp = get_empty_filp(); 226631e6b01fSNick Piggin if (!filp) 226731e6b01fSNick Piggin return ERR_PTR(-ENFILE); 226831e6b01fSNick Piggin 226947c805dcSAl Viro filp->f_flags = op->open_flag; 227073d049a4SAl Viro nd->intent.open.file = filp; 227173d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 227273d049a4SAl Viro nd->intent.open.create_mode = op->mode; 227331e6b01fSNick Piggin 227473d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 227531e6b01fSNick Piggin if (unlikely(error)) 227613aab428SAl Viro goto out_filp; 227731e6b01fSNick Piggin 2278fe2d35ffSAl Viro current->total_link_count = 0; 227973d049a4SAl Viro error = link_path_walk(pathname, nd); 228031e6b01fSNick Piggin if (unlikely(error)) 228131e6b01fSNick Piggin goto out_filp; 22821da177e4SLinus Torvalds 228373d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2284806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 22857b9337aaSNick Piggin struct path link = path; 2286def4af30SAl Viro void *cookie; 2287574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 228873d049a4SAl Viro path_put_conditional(&path, nd); 228973d049a4SAl Viro path_put(&nd->path); 229040b39136SAl Viro filp = ERR_PTR(-ELOOP); 229140b39136SAl Viro break; 229240b39136SAl Viro } 229373d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 229473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2295574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2296c3e380b0SAl Viro if (unlikely(error)) 2297f1afe9efSAl Viro filp = ERR_PTR(error); 2298c3e380b0SAl Viro else 229973d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2300574197e0SAl Viro put_link(nd, &link, cookie); 2301806b681cSAl Viro } 230210fa8e62SAl Viro out: 230373d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 230473d049a4SAl Viro path_put(&nd->root); 2305fe2d35ffSAl Viro if (base) 2306fe2d35ffSAl Viro fput(base); 230773d049a4SAl Viro release_open_intent(nd); 230810fa8e62SAl Viro return filp; 23091da177e4SLinus Torvalds 231031e6b01fSNick Piggin out_filp: 231110fa8e62SAl Viro filp = ERR_PTR(error); 231210fa8e62SAl Viro goto out; 2313de459215SKirill Korotaev } 23141da177e4SLinus Torvalds 231513aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 231613aab428SAl Viro const struct open_flags *op, int flags) 231713aab428SAl Viro { 231873d049a4SAl Viro struct nameidata nd; 231913aab428SAl Viro struct file *filp; 232013aab428SAl Viro 232173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 232213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 232373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 232413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 232573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 232613aab428SAl Viro return filp; 232713aab428SAl Viro } 232813aab428SAl Viro 232973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 233073d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 233173d049a4SAl Viro { 233273d049a4SAl Viro struct nameidata nd; 233373d049a4SAl Viro struct file *file; 233473d049a4SAl Viro 233573d049a4SAl Viro nd.root.mnt = mnt; 233673d049a4SAl Viro nd.root.dentry = dentry; 233773d049a4SAl Viro 233873d049a4SAl Viro flags |= LOOKUP_ROOT; 233973d049a4SAl Viro 2340bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 234173d049a4SAl Viro return ERR_PTR(-ELOOP); 234273d049a4SAl Viro 234373d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 234473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 234573d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 234673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 234773d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 234873d049a4SAl Viro return file; 234973d049a4SAl Viro } 235073d049a4SAl Viro 23511da177e4SLinus Torvalds /** 23521da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23531da177e4SLinus Torvalds * @nd: nameidata info 23541da177e4SLinus Torvalds * @is_dir: directory flag 23551da177e4SLinus Torvalds * 23561da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23571da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2358c663e5d8SChristoph Hellwig * 23594ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23601da177e4SLinus Torvalds */ 23611da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23621da177e4SLinus Torvalds { 2363c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23641da177e4SLinus Torvalds 23654ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2366c663e5d8SChristoph Hellwig /* 2367c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2368c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2369c663e5d8SChristoph Hellwig */ 23701da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23711da177e4SLinus Torvalds goto fail; 23721da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 23733516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2374a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2375c663e5d8SChristoph Hellwig 2376c663e5d8SChristoph Hellwig /* 2377c663e5d8SChristoph Hellwig * Do the final lookup. 2378c663e5d8SChristoph Hellwig */ 237949705b77SChristoph Hellwig dentry = lookup_hash(nd); 23801da177e4SLinus Torvalds if (IS_ERR(dentry)) 23811da177e4SLinus Torvalds goto fail; 2382c663e5d8SChristoph Hellwig 2383e9baf6e5SAl Viro if (dentry->d_inode) 2384e9baf6e5SAl Viro goto eexist; 2385c663e5d8SChristoph Hellwig /* 2386c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2387c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2388c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2389c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2390c663e5d8SChristoph Hellwig */ 2391e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 23921da177e4SLinus Torvalds dput(dentry); 23931da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2394e9baf6e5SAl Viro } 2395e9baf6e5SAl Viro return dentry; 2396e9baf6e5SAl Viro eexist: 2397e9baf6e5SAl Viro dput(dentry); 2398e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 23991da177e4SLinus Torvalds fail: 24001da177e4SLinus Torvalds return dentry; 24011da177e4SLinus Torvalds } 2402f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 24031da177e4SLinus Torvalds 24041da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24051da177e4SLinus Torvalds { 2406a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24071da177e4SLinus Torvalds 24081da177e4SLinus Torvalds if (error) 24091da177e4SLinus Torvalds return error; 24101da177e4SLinus Torvalds 2411e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2412e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 24131da177e4SLinus Torvalds return -EPERM; 24141da177e4SLinus Torvalds 2415acfa4380SAl Viro if (!dir->i_op->mknod) 24161da177e4SLinus Torvalds return -EPERM; 24171da177e4SLinus Torvalds 241808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 241908ce5f16SSerge E. Hallyn if (error) 242008ce5f16SSerge E. Hallyn return error; 242108ce5f16SSerge E. Hallyn 24221da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24231da177e4SLinus Torvalds if (error) 24241da177e4SLinus Torvalds return error; 24251da177e4SLinus Torvalds 24261da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2427a74574aaSStephen Smalley if (!error) 2428f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24291da177e4SLinus Torvalds return error; 24301da177e4SLinus Torvalds } 24311da177e4SLinus Torvalds 2432463c3197SDave Hansen static int may_mknod(mode_t mode) 2433463c3197SDave Hansen { 2434463c3197SDave Hansen switch (mode & S_IFMT) { 2435463c3197SDave Hansen case S_IFREG: 2436463c3197SDave Hansen case S_IFCHR: 2437463c3197SDave Hansen case S_IFBLK: 2438463c3197SDave Hansen case S_IFIFO: 2439463c3197SDave Hansen case S_IFSOCK: 2440463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2441463c3197SDave Hansen return 0; 2442463c3197SDave Hansen case S_IFDIR: 2443463c3197SDave Hansen return -EPERM; 2444463c3197SDave Hansen default: 2445463c3197SDave Hansen return -EINVAL; 2446463c3197SDave Hansen } 2447463c3197SDave Hansen } 2448463c3197SDave Hansen 24492e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24502e4d0924SHeiko Carstens unsigned, dev) 24511da177e4SLinus Torvalds { 24522ad94ae6SAl Viro int error; 24531da177e4SLinus Torvalds char *tmp; 24541da177e4SLinus Torvalds struct dentry *dentry; 24551da177e4SLinus Torvalds struct nameidata nd; 24561da177e4SLinus Torvalds 24571da177e4SLinus Torvalds if (S_ISDIR(mode)) 24581da177e4SLinus Torvalds return -EPERM; 24591da177e4SLinus Torvalds 24602ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24611da177e4SLinus Torvalds if (error) 24622ad94ae6SAl Viro return error; 24632ad94ae6SAl Viro 24641da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2465463c3197SDave Hansen if (IS_ERR(dentry)) { 24661da177e4SLinus Torvalds error = PTR_ERR(dentry); 2467463c3197SDave Hansen goto out_unlock; 2468463c3197SDave Hansen } 24694ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2470ce3b0f8dSAl Viro mode &= ~current_umask(); 2471463c3197SDave Hansen error = may_mknod(mode); 2472463c3197SDave Hansen if (error) 2473463c3197SDave Hansen goto out_dput; 2474463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2475463c3197SDave Hansen if (error) 2476463c3197SDave Hansen goto out_dput; 2477be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2478be6d3e56SKentaro Takeda if (error) 2479be6d3e56SKentaro Takeda goto out_drop_write; 24801da177e4SLinus Torvalds switch (mode & S_IFMT) { 24811da177e4SLinus Torvalds case 0: case S_IFREG: 24824ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 24831da177e4SLinus Torvalds break; 24841da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 24854ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 24861da177e4SLinus Torvalds new_decode_dev(dev)); 24871da177e4SLinus Torvalds break; 24881da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 24894ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 24901da177e4SLinus Torvalds break; 24911da177e4SLinus Torvalds } 2492be6d3e56SKentaro Takeda out_drop_write: 2493463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2494463c3197SDave Hansen out_dput: 24951da177e4SLinus Torvalds dput(dentry); 2496463c3197SDave Hansen out_unlock: 24974ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24981d957f9bSJan Blunck path_put(&nd.path); 24991da177e4SLinus Torvalds putname(tmp); 25001da177e4SLinus Torvalds 25011da177e4SLinus Torvalds return error; 25021da177e4SLinus Torvalds } 25031da177e4SLinus Torvalds 25043480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25055590ff0dSUlrich Drepper { 25065590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25075590ff0dSUlrich Drepper } 25085590ff0dSUlrich Drepper 25091da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25101da177e4SLinus Torvalds { 2511a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25121da177e4SLinus Torvalds 25131da177e4SLinus Torvalds if (error) 25141da177e4SLinus Torvalds return error; 25151da177e4SLinus Torvalds 2516acfa4380SAl Viro if (!dir->i_op->mkdir) 25171da177e4SLinus Torvalds return -EPERM; 25181da177e4SLinus Torvalds 25191da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25201da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25211da177e4SLinus Torvalds if (error) 25221da177e4SLinus Torvalds return error; 25231da177e4SLinus Torvalds 25241da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2525a74574aaSStephen Smalley if (!error) 2526f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25271da177e4SLinus Torvalds return error; 25281da177e4SLinus Torvalds } 25291da177e4SLinus Torvalds 25302e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25311da177e4SLinus Torvalds { 25321da177e4SLinus Torvalds int error = 0; 25331da177e4SLinus Torvalds char * tmp; 25346902d925SDave Hansen struct dentry *dentry; 25356902d925SDave Hansen struct nameidata nd; 25361da177e4SLinus Torvalds 25372ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25382ad94ae6SAl Viro if (error) 25396902d925SDave Hansen goto out_err; 25401da177e4SLinus Torvalds 25411da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25421da177e4SLinus Torvalds error = PTR_ERR(dentry); 25436902d925SDave Hansen if (IS_ERR(dentry)) 25446902d925SDave Hansen goto out_unlock; 25456902d925SDave Hansen 25464ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2547ce3b0f8dSAl Viro mode &= ~current_umask(); 2548463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2549463c3197SDave Hansen if (error) 2550463c3197SDave Hansen goto out_dput; 2551be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2552be6d3e56SKentaro Takeda if (error) 2553be6d3e56SKentaro Takeda goto out_drop_write; 25544ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2555be6d3e56SKentaro Takeda out_drop_write: 2556463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2557463c3197SDave Hansen out_dput: 25581da177e4SLinus Torvalds dput(dentry); 25596902d925SDave Hansen out_unlock: 25604ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25611d957f9bSJan Blunck path_put(&nd.path); 25621da177e4SLinus Torvalds putname(tmp); 25636902d925SDave Hansen out_err: 25641da177e4SLinus Torvalds return error; 25651da177e4SLinus Torvalds } 25661da177e4SLinus Torvalds 25673cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25685590ff0dSUlrich Drepper { 25695590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25705590ff0dSUlrich Drepper } 25715590ff0dSUlrich Drepper 25721da177e4SLinus Torvalds /* 25731da177e4SLinus Torvalds * We try to drop the dentry early: we should have 25741da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 25751da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 25761da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 25771da177e4SLinus Torvalds * 25781da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 25791da177e4SLinus Torvalds * do a 25801da177e4SLinus Torvalds * 25811da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 25821da177e4SLinus Torvalds * return -EBUSY; 25831da177e4SLinus Torvalds * 25841da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 25851da177e4SLinus Torvalds * that is still in use by something else.. 25861da177e4SLinus Torvalds */ 25871da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 25881da177e4SLinus Torvalds { 25891da177e4SLinus Torvalds dget(dentry); 25901da177e4SLinus Torvalds shrink_dcache_parent(dentry); 25911da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2592b7ab39f6SNick Piggin if (dentry->d_count == 2) 25931da177e4SLinus Torvalds __d_drop(dentry); 25941da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 25951da177e4SLinus Torvalds } 25961da177e4SLinus Torvalds 25971da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 25981da177e4SLinus Torvalds { 25991da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26001da177e4SLinus Torvalds 26011da177e4SLinus Torvalds if (error) 26021da177e4SLinus Torvalds return error; 26031da177e4SLinus Torvalds 2604acfa4380SAl Viro if (!dir->i_op->rmdir) 26051da177e4SLinus Torvalds return -EPERM; 26061da177e4SLinus Torvalds 26071b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26081da177e4SLinus Torvalds dentry_unhash(dentry); 26091da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26101da177e4SLinus Torvalds error = -EBUSY; 26111da177e4SLinus Torvalds else { 26121da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 26131da177e4SLinus Torvalds if (!error) { 26141da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2615d83c49f3SAl Viro if (!error) { 26161da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2617d83c49f3SAl Viro dont_mount(dentry); 2618d83c49f3SAl Viro } 26191da177e4SLinus Torvalds } 26201da177e4SLinus Torvalds } 26211b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26221da177e4SLinus Torvalds if (!error) { 26231da177e4SLinus Torvalds d_delete(dentry); 26241da177e4SLinus Torvalds } 26251da177e4SLinus Torvalds dput(dentry); 26261da177e4SLinus Torvalds 26271da177e4SLinus Torvalds return error; 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds 26305590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26311da177e4SLinus Torvalds { 26321da177e4SLinus Torvalds int error = 0; 26331da177e4SLinus Torvalds char * name; 26341da177e4SLinus Torvalds struct dentry *dentry; 26351da177e4SLinus Torvalds struct nameidata nd; 26361da177e4SLinus Torvalds 26372ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26381da177e4SLinus Torvalds if (error) 26392ad94ae6SAl Viro return error; 26401da177e4SLinus Torvalds 26411da177e4SLinus Torvalds switch(nd.last_type) { 26421da177e4SLinus Torvalds case LAST_DOTDOT: 26431da177e4SLinus Torvalds error = -ENOTEMPTY; 26441da177e4SLinus Torvalds goto exit1; 26451da177e4SLinus Torvalds case LAST_DOT: 26461da177e4SLinus Torvalds error = -EINVAL; 26471da177e4SLinus Torvalds goto exit1; 26481da177e4SLinus Torvalds case LAST_ROOT: 26491da177e4SLinus Torvalds error = -EBUSY; 26501da177e4SLinus Torvalds goto exit1; 26511da177e4SLinus Torvalds } 26520612d9fbSOGAWA Hirofumi 26530612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26540612d9fbSOGAWA Hirofumi 26554ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 265649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26571da177e4SLinus Torvalds error = PTR_ERR(dentry); 26586902d925SDave Hansen if (IS_ERR(dentry)) 26596902d925SDave Hansen goto exit2; 26600622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26610622753bSDave Hansen if (error) 26620622753bSDave Hansen goto exit3; 2663be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2664be6d3e56SKentaro Takeda if (error) 2665be6d3e56SKentaro Takeda goto exit4; 26664ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2667be6d3e56SKentaro Takeda exit4: 26680622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26690622753bSDave Hansen exit3: 26701da177e4SLinus Torvalds dput(dentry); 26716902d925SDave Hansen exit2: 26724ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26731da177e4SLinus Torvalds exit1: 26741d957f9bSJan Blunck path_put(&nd.path); 26751da177e4SLinus Torvalds putname(name); 26761da177e4SLinus Torvalds return error; 26771da177e4SLinus Torvalds } 26781da177e4SLinus Torvalds 26793cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 26805590ff0dSUlrich Drepper { 26815590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 26825590ff0dSUlrich Drepper } 26835590ff0dSUlrich Drepper 26841da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 26851da177e4SLinus Torvalds { 26861da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 26871da177e4SLinus Torvalds 26881da177e4SLinus Torvalds if (error) 26891da177e4SLinus Torvalds return error; 26901da177e4SLinus Torvalds 2691acfa4380SAl Viro if (!dir->i_op->unlink) 26921da177e4SLinus Torvalds return -EPERM; 26931da177e4SLinus Torvalds 26941b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26951da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26961da177e4SLinus Torvalds error = -EBUSY; 26971da177e4SLinus Torvalds else { 26981da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2699bec1052eSAl Viro if (!error) { 27001da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2701bec1052eSAl Viro if (!error) 2702d83c49f3SAl Viro dont_mount(dentry); 2703bec1052eSAl Viro } 27041da177e4SLinus Torvalds } 27051b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27061da177e4SLinus Torvalds 27071da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27081da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2709ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27101da177e4SLinus Torvalds d_delete(dentry); 27111da177e4SLinus Torvalds } 27120eeca283SRobert Love 27131da177e4SLinus Torvalds return error; 27141da177e4SLinus Torvalds } 27151da177e4SLinus Torvalds 27161da177e4SLinus Torvalds /* 27171da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27181b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27191da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27201da177e4SLinus Torvalds * while waiting on the I/O. 27211da177e4SLinus Torvalds */ 27225590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27231da177e4SLinus Torvalds { 27242ad94ae6SAl Viro int error; 27251da177e4SLinus Torvalds char *name; 27261da177e4SLinus Torvalds struct dentry *dentry; 27271da177e4SLinus Torvalds struct nameidata nd; 27281da177e4SLinus Torvalds struct inode *inode = NULL; 27291da177e4SLinus Torvalds 27302ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27311da177e4SLinus Torvalds if (error) 27322ad94ae6SAl Viro return error; 27332ad94ae6SAl Viro 27341da177e4SLinus Torvalds error = -EISDIR; 27351da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27361da177e4SLinus Torvalds goto exit1; 27370612d9fbSOGAWA Hirofumi 27380612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27390612d9fbSOGAWA Hirofumi 27404ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 274149705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27421da177e4SLinus Torvalds error = PTR_ERR(dentry); 27431da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27441da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 27451da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 27461da177e4SLinus Torvalds goto slashes; 27471da177e4SLinus Torvalds inode = dentry->d_inode; 27481da177e4SLinus Torvalds if (inode) 27497de9c6eeSAl Viro ihold(inode); 27500622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27510622753bSDave Hansen if (error) 27520622753bSDave Hansen goto exit2; 2753be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2754be6d3e56SKentaro Takeda if (error) 2755be6d3e56SKentaro Takeda goto exit3; 27564ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2757be6d3e56SKentaro Takeda exit3: 27580622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27591da177e4SLinus Torvalds exit2: 27601da177e4SLinus Torvalds dput(dentry); 27611da177e4SLinus Torvalds } 27624ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27631da177e4SLinus Torvalds if (inode) 27641da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27651da177e4SLinus Torvalds exit1: 27661d957f9bSJan Blunck path_put(&nd.path); 27671da177e4SLinus Torvalds putname(name); 27681da177e4SLinus Torvalds return error; 27691da177e4SLinus Torvalds 27701da177e4SLinus Torvalds slashes: 27711da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27721da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 27731da177e4SLinus Torvalds goto exit2; 27741da177e4SLinus Torvalds } 27751da177e4SLinus Torvalds 27762e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 27775590ff0dSUlrich Drepper { 27785590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 27795590ff0dSUlrich Drepper return -EINVAL; 27805590ff0dSUlrich Drepper 27815590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 27825590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 27835590ff0dSUlrich Drepper 27845590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 27855590ff0dSUlrich Drepper } 27865590ff0dSUlrich Drepper 27873480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 27885590ff0dSUlrich Drepper { 27895590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 27905590ff0dSUlrich Drepper } 27915590ff0dSUlrich Drepper 2792db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 27931da177e4SLinus Torvalds { 2794a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27951da177e4SLinus Torvalds 27961da177e4SLinus Torvalds if (error) 27971da177e4SLinus Torvalds return error; 27981da177e4SLinus Torvalds 2799acfa4380SAl Viro if (!dir->i_op->symlink) 28001da177e4SLinus Torvalds return -EPERM; 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28031da177e4SLinus Torvalds if (error) 28041da177e4SLinus Torvalds return error; 28051da177e4SLinus Torvalds 28061da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2807a74574aaSStephen Smalley if (!error) 2808f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28091da177e4SLinus Torvalds return error; 28101da177e4SLinus Torvalds } 28111da177e4SLinus Torvalds 28122e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28132e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28141da177e4SLinus Torvalds { 28152ad94ae6SAl Viro int error; 28161da177e4SLinus Torvalds char *from; 28171da177e4SLinus Torvalds char *to; 28186902d925SDave Hansen struct dentry *dentry; 28196902d925SDave Hansen struct nameidata nd; 28201da177e4SLinus Torvalds 28211da177e4SLinus Torvalds from = getname(oldname); 28221da177e4SLinus Torvalds if (IS_ERR(from)) 28231da177e4SLinus Torvalds return PTR_ERR(from); 28242ad94ae6SAl Viro 28252ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28262ad94ae6SAl Viro if (error) 28276902d925SDave Hansen goto out_putname; 28281da177e4SLinus Torvalds 28291da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28301da177e4SLinus Torvalds error = PTR_ERR(dentry); 28316902d925SDave Hansen if (IS_ERR(dentry)) 28326902d925SDave Hansen goto out_unlock; 28336902d925SDave Hansen 283475c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 283575c3f29dSDave Hansen if (error) 283675c3f29dSDave Hansen goto out_dput; 2837be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2838be6d3e56SKentaro Takeda if (error) 2839be6d3e56SKentaro Takeda goto out_drop_write; 2840db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2841be6d3e56SKentaro Takeda out_drop_write: 284275c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 284375c3f29dSDave Hansen out_dput: 28441da177e4SLinus Torvalds dput(dentry); 28456902d925SDave Hansen out_unlock: 28464ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28471d957f9bSJan Blunck path_put(&nd.path); 28481da177e4SLinus Torvalds putname(to); 28496902d925SDave Hansen out_putname: 28501da177e4SLinus Torvalds putname(from); 28511da177e4SLinus Torvalds return error; 28521da177e4SLinus Torvalds } 28531da177e4SLinus Torvalds 28543480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28555590ff0dSUlrich Drepper { 28565590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28575590ff0dSUlrich Drepper } 28585590ff0dSUlrich Drepper 28591da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28601da177e4SLinus Torvalds { 28611da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28621da177e4SLinus Torvalds int error; 28631da177e4SLinus Torvalds 28641da177e4SLinus Torvalds if (!inode) 28651da177e4SLinus Torvalds return -ENOENT; 28661da177e4SLinus Torvalds 2867a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28681da177e4SLinus Torvalds if (error) 28691da177e4SLinus Torvalds return error; 28701da177e4SLinus Torvalds 28711da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28721da177e4SLinus Torvalds return -EXDEV; 28731da177e4SLinus Torvalds 28741da177e4SLinus Torvalds /* 28751da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 28761da177e4SLinus Torvalds */ 28771da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 28781da177e4SLinus Torvalds return -EPERM; 2879acfa4380SAl Viro if (!dir->i_op->link) 28801da177e4SLinus Torvalds return -EPERM; 28817e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 28821da177e4SLinus Torvalds return -EPERM; 28831da177e4SLinus Torvalds 28841da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 28851da177e4SLinus Torvalds if (error) 28861da177e4SLinus Torvalds return error; 28871da177e4SLinus Torvalds 28887e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2889aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2890aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2891aae8a97dSAneesh Kumar K.V error = -ENOENT; 2892aae8a97dSAneesh Kumar K.V else 28931da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 28947e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2895e31e14ecSStephen Smalley if (!error) 28967e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 28971da177e4SLinus Torvalds return error; 28981da177e4SLinus Torvalds } 28991da177e4SLinus Torvalds 29001da177e4SLinus Torvalds /* 29011da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29021da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29031da177e4SLinus Torvalds * newname. --KAB 29041da177e4SLinus Torvalds * 29051da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29061da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29071da177e4SLinus Torvalds * and other special files. --ADM 29081da177e4SLinus Torvalds */ 29092e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29102e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29111da177e4SLinus Torvalds { 29121da177e4SLinus Torvalds struct dentry *new_dentry; 29132d8f3038SAl Viro struct nameidata nd; 29142d8f3038SAl Viro struct path old_path; 291511a7b371SAneesh Kumar K.V int how = 0; 29161da177e4SLinus Torvalds int error; 29171da177e4SLinus Torvalds char *to; 29181da177e4SLinus Torvalds 291911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2920c04030e1SUlrich Drepper return -EINVAL; 292111a7b371SAneesh Kumar K.V /* 292211a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 292311a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 292411a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 292511a7b371SAneesh Kumar K.V */ 292611a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 292711a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 292811a7b371SAneesh Kumar K.V return -ENOENT; 292911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 293011a7b371SAneesh Kumar K.V } 2931c04030e1SUlrich Drepper 293211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 293311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 293411a7b371SAneesh Kumar K.V 293511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29361da177e4SLinus Torvalds if (error) 29372ad94ae6SAl Viro return error; 29382ad94ae6SAl Viro 29392ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29401da177e4SLinus Torvalds if (error) 29411da177e4SLinus Torvalds goto out; 29421da177e4SLinus Torvalds error = -EXDEV; 29432d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29441da177e4SLinus Torvalds goto out_release; 29451da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29461da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29476902d925SDave Hansen if (IS_ERR(new_dentry)) 29486902d925SDave Hansen goto out_unlock; 294975c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 295075c3f29dSDave Hansen if (error) 295175c3f29dSDave Hansen goto out_dput; 2952be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2953be6d3e56SKentaro Takeda if (error) 2954be6d3e56SKentaro Takeda goto out_drop_write; 29552d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2956be6d3e56SKentaro Takeda out_drop_write: 295775c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 295875c3f29dSDave Hansen out_dput: 29591da177e4SLinus Torvalds dput(new_dentry); 29606902d925SDave Hansen out_unlock: 29614ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29621da177e4SLinus Torvalds out_release: 29631d957f9bSJan Blunck path_put(&nd.path); 29642ad94ae6SAl Viro putname(to); 29651da177e4SLinus Torvalds out: 29662d8f3038SAl Viro path_put(&old_path); 29671da177e4SLinus Torvalds 29681da177e4SLinus Torvalds return error; 29691da177e4SLinus Torvalds } 29701da177e4SLinus Torvalds 29713480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29725590ff0dSUlrich Drepper { 2973c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29745590ff0dSUlrich Drepper } 29755590ff0dSUlrich Drepper 29761da177e4SLinus Torvalds /* 29771da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29781da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29791da177e4SLinus Torvalds * Problems: 29801da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29811da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29821da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2983a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29841da177e4SLinus Torvalds * story. 29851da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29861b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29871da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29881da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2989a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 29901da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 29911da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 29921da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2993a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 29941da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 29951da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 29961da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 29971da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 29981da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 29991da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 30001da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 30011da177e4SLinus Torvalds * trick as in rmdir(). 30021da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 30031b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 30041da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3005c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 30061da177e4SLinus Torvalds * locking]. 30071da177e4SLinus Torvalds */ 300875c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30091da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30101da177e4SLinus Torvalds { 30111da177e4SLinus Torvalds int error = 0; 30121da177e4SLinus Torvalds struct inode *target; 30131da177e4SLinus Torvalds 30141da177e4SLinus Torvalds /* 30151da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30161da177e4SLinus Torvalds * we'll need to flip '..'. 30171da177e4SLinus Torvalds */ 30181da177e4SLinus Torvalds if (new_dir != old_dir) { 3019f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30201da177e4SLinus Torvalds if (error) 30211da177e4SLinus Torvalds return error; 30221da177e4SLinus Torvalds } 30231da177e4SLinus Torvalds 30241da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30251da177e4SLinus Torvalds if (error) 30261da177e4SLinus Torvalds return error; 30271da177e4SLinus Torvalds 30281da177e4SLinus Torvalds target = new_dentry->d_inode; 3029d83c49f3SAl Viro if (target) 30301b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30311da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30321da177e4SLinus Torvalds error = -EBUSY; 3033d83c49f3SAl Viro else { 3034d83c49f3SAl Viro if (target) 3035d83c49f3SAl Viro dentry_unhash(new_dentry); 30361da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3037d83c49f3SAl Viro } 30381da177e4SLinus Torvalds if (target) { 3039d83c49f3SAl Viro if (!error) { 30401da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3041d83c49f3SAl Viro dont_mount(new_dentry); 3042d83c49f3SAl Viro } 30431b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30441da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 30451da177e4SLinus Torvalds d_rehash(new_dentry); 30461da177e4SLinus Torvalds dput(new_dentry); 30471da177e4SLinus Torvalds } 3048e31e14ecSStephen Smalley if (!error) 3049349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30501da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30511da177e4SLinus Torvalds return error; 30521da177e4SLinus Torvalds } 30531da177e4SLinus Torvalds 305475c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30551da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30561da177e4SLinus Torvalds { 30571da177e4SLinus Torvalds struct inode *target; 30581da177e4SLinus Torvalds int error; 30591da177e4SLinus Torvalds 30601da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30611da177e4SLinus Torvalds if (error) 30621da177e4SLinus Torvalds return error; 30631da177e4SLinus Torvalds 30641da177e4SLinus Torvalds dget(new_dentry); 30651da177e4SLinus Torvalds target = new_dentry->d_inode; 30661da177e4SLinus Torvalds if (target) 30671b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30681da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30691da177e4SLinus Torvalds error = -EBUSY; 30701da177e4SLinus Torvalds else 30711da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30721da177e4SLinus Torvalds if (!error) { 3073bec1052eSAl Viro if (target) 3074d83c49f3SAl Viro dont_mount(new_dentry); 3075349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30761da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 30771da177e4SLinus Torvalds } 30781da177e4SLinus Torvalds if (target) 30791b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30801da177e4SLinus Torvalds dput(new_dentry); 30811da177e4SLinus Torvalds return error; 30821da177e4SLinus Torvalds } 30831da177e4SLinus Torvalds 30841da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30851da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30861da177e4SLinus Torvalds { 30871da177e4SLinus Torvalds int error; 30881da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 308959b0df21SEric Paris const unsigned char *old_name; 30901da177e4SLinus Torvalds 30911da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 30921da177e4SLinus Torvalds return 0; 30931da177e4SLinus Torvalds 30941da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 30951da177e4SLinus Torvalds if (error) 30961da177e4SLinus Torvalds return error; 30971da177e4SLinus Torvalds 30981da177e4SLinus Torvalds if (!new_dentry->d_inode) 3099a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 31001da177e4SLinus Torvalds else 31011da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31021da177e4SLinus Torvalds if (error) 31031da177e4SLinus Torvalds return error; 31041da177e4SLinus Torvalds 3105acfa4380SAl Viro if (!old_dir->i_op->rename) 31061da177e4SLinus Torvalds return -EPERM; 31071da177e4SLinus Torvalds 31080eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31090eeca283SRobert Love 31101da177e4SLinus Torvalds if (is_dir) 31111da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31121da177e4SLinus Torvalds else 31131da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3114123df294SAl Viro if (!error) 3115123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31165a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31170eeca283SRobert Love fsnotify_oldname_free(old_name); 31180eeca283SRobert Love 31191da177e4SLinus Torvalds return error; 31201da177e4SLinus Torvalds } 31211da177e4SLinus Torvalds 31222e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31232e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31241da177e4SLinus Torvalds { 31251da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31261da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31271da177e4SLinus Torvalds struct dentry *trap; 31281da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31292ad94ae6SAl Viro char *from; 31302ad94ae6SAl Viro char *to; 31312ad94ae6SAl Viro int error; 31321da177e4SLinus Torvalds 31332ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31341da177e4SLinus Torvalds if (error) 31351da177e4SLinus Torvalds goto exit; 31361da177e4SLinus Torvalds 31372ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31381da177e4SLinus Torvalds if (error) 31391da177e4SLinus Torvalds goto exit1; 31401da177e4SLinus Torvalds 31411da177e4SLinus Torvalds error = -EXDEV; 31424ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31431da177e4SLinus Torvalds goto exit2; 31441da177e4SLinus Torvalds 31454ac91378SJan Blunck old_dir = oldnd.path.dentry; 31461da177e4SLinus Torvalds error = -EBUSY; 31471da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31481da177e4SLinus Torvalds goto exit2; 31491da177e4SLinus Torvalds 31504ac91378SJan Blunck new_dir = newnd.path.dentry; 31511da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31521da177e4SLinus Torvalds goto exit2; 31531da177e4SLinus Torvalds 31540612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31550612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31564e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31570612d9fbSOGAWA Hirofumi 31581da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31591da177e4SLinus Torvalds 316049705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31611da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31621da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31631da177e4SLinus Torvalds goto exit3; 31641da177e4SLinus Torvalds /* source must exist */ 31651da177e4SLinus Torvalds error = -ENOENT; 31661da177e4SLinus Torvalds if (!old_dentry->d_inode) 31671da177e4SLinus Torvalds goto exit4; 31681da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31691da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31701da177e4SLinus Torvalds error = -ENOTDIR; 31711da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31721da177e4SLinus Torvalds goto exit4; 31731da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31741da177e4SLinus Torvalds goto exit4; 31751da177e4SLinus Torvalds } 31761da177e4SLinus Torvalds /* source should not be ancestor of target */ 31771da177e4SLinus Torvalds error = -EINVAL; 31781da177e4SLinus Torvalds if (old_dentry == trap) 31791da177e4SLinus Torvalds goto exit4; 318049705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31811da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31821da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31831da177e4SLinus Torvalds goto exit4; 31841da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31851da177e4SLinus Torvalds error = -ENOTEMPTY; 31861da177e4SLinus Torvalds if (new_dentry == trap) 31871da177e4SLinus Torvalds goto exit5; 31881da177e4SLinus Torvalds 31899079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 31909079b1ebSDave Hansen if (error) 31919079b1ebSDave Hansen goto exit5; 3192be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3193be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3194be6d3e56SKentaro Takeda if (error) 3195be6d3e56SKentaro Takeda goto exit6; 31961da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 31971da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3198be6d3e56SKentaro Takeda exit6: 31999079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 32001da177e4SLinus Torvalds exit5: 32011da177e4SLinus Torvalds dput(new_dentry); 32021da177e4SLinus Torvalds exit4: 32031da177e4SLinus Torvalds dput(old_dentry); 32041da177e4SLinus Torvalds exit3: 32051da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32061da177e4SLinus Torvalds exit2: 32071d957f9bSJan Blunck path_put(&newnd.path); 32082ad94ae6SAl Viro putname(to); 32091da177e4SLinus Torvalds exit1: 32101d957f9bSJan Blunck path_put(&oldnd.path); 32111da177e4SLinus Torvalds putname(from); 32122ad94ae6SAl Viro exit: 32131da177e4SLinus Torvalds return error; 32141da177e4SLinus Torvalds } 32151da177e4SLinus Torvalds 3216a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32175590ff0dSUlrich Drepper { 32185590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32195590ff0dSUlrich Drepper } 32205590ff0dSUlrich Drepper 32211da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32221da177e4SLinus Torvalds { 32231da177e4SLinus Torvalds int len; 32241da177e4SLinus Torvalds 32251da177e4SLinus Torvalds len = PTR_ERR(link); 32261da177e4SLinus Torvalds if (IS_ERR(link)) 32271da177e4SLinus Torvalds goto out; 32281da177e4SLinus Torvalds 32291da177e4SLinus Torvalds len = strlen(link); 32301da177e4SLinus Torvalds if (len > (unsigned) buflen) 32311da177e4SLinus Torvalds len = buflen; 32321da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32331da177e4SLinus Torvalds len = -EFAULT; 32341da177e4SLinus Torvalds out: 32351da177e4SLinus Torvalds return len; 32361da177e4SLinus Torvalds } 32371da177e4SLinus Torvalds 32381da177e4SLinus Torvalds /* 32391da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32401da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32411da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32421da177e4SLinus Torvalds */ 32431da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32441da177e4SLinus Torvalds { 32451da177e4SLinus Torvalds struct nameidata nd; 3246cc314eefSLinus Torvalds void *cookie; 3247694a1764SMarcin Slusarz int res; 3248cc314eefSLinus Torvalds 32491da177e4SLinus Torvalds nd.depth = 0; 3250cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3251694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3252694a1764SMarcin Slusarz return PTR_ERR(cookie); 3253694a1764SMarcin Slusarz 3254694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32551da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3256cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3257694a1764SMarcin Slusarz return res; 32581da177e4SLinus Torvalds } 32591da177e4SLinus Torvalds 32601da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32611da177e4SLinus Torvalds { 32621da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32631da177e4SLinus Torvalds } 32641da177e4SLinus Torvalds 32651da177e4SLinus Torvalds /* get the link contents into pagecache */ 32661da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32671da177e4SLinus Torvalds { 3268ebd09abbSDuane Griffin char *kaddr; 32691da177e4SLinus Torvalds struct page *page; 32701da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3271090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32721da177e4SLinus Torvalds if (IS_ERR(page)) 32736fe6900eSNick Piggin return (char*)page; 32741da177e4SLinus Torvalds *ppage = page; 3275ebd09abbSDuane Griffin kaddr = kmap(page); 3276ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3277ebd09abbSDuane Griffin return kaddr; 32781da177e4SLinus Torvalds } 32791da177e4SLinus Torvalds 32801da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32811da177e4SLinus Torvalds { 32821da177e4SLinus Torvalds struct page *page = NULL; 32831da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32841da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32851da177e4SLinus Torvalds if (page) { 32861da177e4SLinus Torvalds kunmap(page); 32871da177e4SLinus Torvalds page_cache_release(page); 32881da177e4SLinus Torvalds } 32891da177e4SLinus Torvalds return res; 32901da177e4SLinus Torvalds } 32911da177e4SLinus Torvalds 3292cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 32931da177e4SLinus Torvalds { 3294cc314eefSLinus Torvalds struct page *page = NULL; 32951da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3296cc314eefSLinus Torvalds return page; 32971da177e4SLinus Torvalds } 32981da177e4SLinus Torvalds 3299cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 33001da177e4SLinus Torvalds { 3301cc314eefSLinus Torvalds struct page *page = cookie; 3302cc314eefSLinus Torvalds 3303cc314eefSLinus Torvalds if (page) { 33041da177e4SLinus Torvalds kunmap(page); 33051da177e4SLinus Torvalds page_cache_release(page); 33061da177e4SLinus Torvalds } 33071da177e4SLinus Torvalds } 33081da177e4SLinus Torvalds 330954566b2cSNick Piggin /* 331054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 331154566b2cSNick Piggin */ 331254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33131da177e4SLinus Torvalds { 33141da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33150adb25d2SKirill Korotaev struct page *page; 3316afddba49SNick Piggin void *fsdata; 3317beb497abSDmitriy Monakhov int err; 33181da177e4SLinus Torvalds char *kaddr; 331954566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 332054566b2cSNick Piggin if (nofs) 332154566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33221da177e4SLinus Torvalds 33237e53cac4SNeilBrown retry: 3324afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 332554566b2cSNick Piggin flags, &page, &fsdata); 33261da177e4SLinus Torvalds if (err) 3327afddba49SNick Piggin goto fail; 3328afddba49SNick Piggin 33291da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33301da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33311da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3332afddba49SNick Piggin 3333afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3334afddba49SNick Piggin page, fsdata); 33351da177e4SLinus Torvalds if (err < 0) 33361da177e4SLinus Torvalds goto fail; 3337afddba49SNick Piggin if (err < len-1) 3338afddba49SNick Piggin goto retry; 3339afddba49SNick Piggin 33401da177e4SLinus Torvalds mark_inode_dirty(inode); 33411da177e4SLinus Torvalds return 0; 33421da177e4SLinus Torvalds fail: 33431da177e4SLinus Torvalds return err; 33441da177e4SLinus Torvalds } 33451da177e4SLinus Torvalds 33460adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33470adb25d2SKirill Korotaev { 33480adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 334954566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33500adb25d2SKirill Korotaev } 33510adb25d2SKirill Korotaev 335292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33531da177e4SLinus Torvalds .readlink = generic_readlink, 33541da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33551da177e4SLinus Torvalds .put_link = page_put_link, 33561da177e4SLinus Torvalds }; 33571da177e4SLinus Torvalds 33582d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3359cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33601da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33611da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33621da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33631da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33641da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33651da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33661da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33671da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33681da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33690adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33701da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33711da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3372c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3373d1811465SAl Viro EXPORT_SYMBOL(kern_path); 337416f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3375f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33768c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 33771da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33781da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33791da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33801da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33811da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33821da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33831da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33851da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33861da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33871da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33881da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33891da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 33901da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3391