11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/pagemap.h> 230eeca283SRobert Love #include <linux/fsnotify.h> 241da177e4SLinus Torvalds #include <linux/personality.h> 251da177e4SLinus Torvalds #include <linux/security.h> 266146f0d5SMimi Zohar #include <linux/ima.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 345ad4e53bSAl Viro #include <linux/fs_struct.h> 351da177e4SLinus Torvalds #include <asm/uaccess.h> 361da177e4SLinus Torvalds 37e81e3f4dSEric Paris #include "internal.h" 38e81e3f4dSEric Paris 391da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 401da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 411da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 421da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 431da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 461da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 471da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 481da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 491da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 501da177e4SLinus Torvalds * the special cases of the former code. 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 531da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 541da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 571da177e4SLinus Torvalds * resolution to correspond with current state of the code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 601da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 611da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 621da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 631da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 641da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 651da177e4SLinus Torvalds */ 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 681da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 691da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 701da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 711da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 721da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7325985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1111da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1121da177e4SLinus Torvalds * kernel data space before using them.. 1131da177e4SLinus Torvalds * 1141da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1151da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1161da177e4SLinus Torvalds */ 117858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1181da177e4SLinus Torvalds { 1191da177e4SLinus Torvalds int retval; 1201da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1231da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1241da177e4SLinus Torvalds return -EFAULT; 1251da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1261da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1301da177e4SLinus Torvalds if (retval > 0) { 1311da177e4SLinus Torvalds if (retval < len) 1321da177e4SLinus Torvalds return 0; 1331da177e4SLinus Torvalds return -ENAMETOOLONG; 1341da177e4SLinus Torvalds } else if (!retval) 1351da177e4SLinus Torvalds retval = -ENOENT; 1361da177e4SLinus Torvalds return retval; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 139f52e0c11SAl Viro static char *getname_flags(const char __user * filename, int flags) 1401da177e4SLinus Torvalds { 1411da177e4SLinus Torvalds char *tmp, *result; 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1441da177e4SLinus Torvalds tmp = __getname(); 1451da177e4SLinus Torvalds if (tmp) { 1461da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds result = tmp; 1491da177e4SLinus Torvalds if (retval < 0) { 150f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 155f52e0c11SAl Viro } 1561da177e4SLinus Torvalds audit_getname(result); 1571da177e4SLinus Torvalds return result; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 160f52e0c11SAl Viro char *getname(const char __user * filename) 161f52e0c11SAl Viro { 162f52e0c11SAl Viro return getname_flags(filename, 0); 163f52e0c11SAl Viro } 164f52e0c11SAl Viro 1651da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1661da177e4SLinus Torvalds void putname(const char *name) 1671da177e4SLinus Torvalds { 1685ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1691da177e4SLinus Torvalds audit_putname(name); 1701da177e4SLinus Torvalds else 1711da177e4SLinus Torvalds __putname(name); 1721da177e4SLinus Torvalds } 1731da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1741da177e4SLinus Torvalds #endif 1751da177e4SLinus Torvalds 1765909ccaaSLinus Torvalds /* 1775909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1785909ccaaSLinus Torvalds */ 179b74c79e9SNick Piggin static int acl_permission_check(struct inode *inode, int mask, unsigned int flags, 180b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 1815909ccaaSLinus Torvalds { 18226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 1835909ccaaSLinus Torvalds 1845909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 1855909ccaaSLinus Torvalds 186e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 187e795b717SSerge E. Hallyn goto other_perms; 188e795b717SSerge E. Hallyn 1895909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1905909ccaaSLinus Torvalds mode >>= 6; 1915909ccaaSLinus Torvalds else { 1925909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 193b74c79e9SNick Piggin int error = check_acl(inode, mask, flags); 1945909ccaaSLinus Torvalds if (error != -EAGAIN) 1955909ccaaSLinus Torvalds return error; 1965909ccaaSLinus Torvalds } 1975909ccaaSLinus Torvalds 1985909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1995909ccaaSLinus Torvalds mode >>= 3; 2005909ccaaSLinus Torvalds } 2015909ccaaSLinus Torvalds 202e795b717SSerge E. Hallyn other_perms: 2035909ccaaSLinus Torvalds /* 2045909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2055909ccaaSLinus Torvalds */ 2065909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 2075909ccaaSLinus Torvalds return 0; 2085909ccaaSLinus Torvalds return -EACCES; 2095909ccaaSLinus Torvalds } 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds /** 2121da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2131da177e4SLinus Torvalds * @inode: inode to check access rights for 2141da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2151da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 21639191628SRandy Dunlap * @flags: IPERM_FLAG_ flags. 2171da177e4SLinus Torvalds * 2181da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2191da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2201da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 221b74c79e9SNick Piggin * are used for other things. 222b74c79e9SNick Piggin * 223b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 224b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 225b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2261da177e4SLinus Torvalds */ 227b74c79e9SNick Piggin int generic_permission(struct inode *inode, int mask, unsigned int flags, 228b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 2291da177e4SLinus Torvalds { 2305909ccaaSLinus Torvalds int ret; 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds /* 2335909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2341da177e4SLinus Torvalds */ 235b74c79e9SNick Piggin ret = acl_permission_check(inode, mask, flags, check_acl); 2365909ccaaSLinus Torvalds if (ret != -EACCES) 2375909ccaaSLinus Torvalds return ret; 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds /* 2401da177e4SLinus Torvalds * Read/write DACs are always overridable. 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 /** 472834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 473834f2a4aSTrond Myklebust * @nd: pointer to nameidata 474834f2a4aSTrond Myklebust */ 475834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 476834f2a4aSTrond Myklebust { 4772dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4782dab5974SLinus Torvalds 4792dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4802dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4812dab5974SLinus Torvalds put_filp(file); 482834f2a4aSTrond Myklebust else 4832dab5974SLinus Torvalds fput(file); 4842dab5974SLinus Torvalds } 485834f2a4aSTrond Myklebust } 486834f2a4aSTrond Myklebust 487f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 48834286d66SNick Piggin { 489f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 49034286d66SNick Piggin } 49134286d66SNick Piggin 492f5e1c1c1SAl Viro static struct dentry * 493bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 494bcdc5e01SIan Kent { 495f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 496bcdc5e01SIan Kent if (unlikely(status <= 0)) { 497bcdc5e01SIan Kent /* 498bcdc5e01SIan Kent * The dentry failed validation. 499bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 500bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 501bcdc5e01SIan Kent * to return a fail status. 502bcdc5e01SIan Kent */ 50334286d66SNick Piggin if (status < 0) { 50434286d66SNick Piggin dput(dentry); 50534286d66SNick Piggin dentry = ERR_PTR(status); 506f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 507bcdc5e01SIan Kent dput(dentry); 508bcdc5e01SIan Kent dentry = NULL; 509bcdc5e01SIan Kent } 510bcdc5e01SIan Kent } 511f5e1c1c1SAl Viro return dentry; 512f5e1c1c1SAl Viro } 513f5e1c1c1SAl Viro 5149f1fafeeSAl Viro /** 5159f1fafeeSAl Viro * complete_walk - successful completion of path walk 5169f1fafeeSAl Viro * @nd: pointer nameidata 51739159de2SJeff Layton * 5189f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5199f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5209f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5219f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5229f1fafeeSAl Viro * need to drop nd->path. 52339159de2SJeff Layton */ 5249f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 52539159de2SJeff Layton { 52616c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 52739159de2SJeff Layton int status; 52839159de2SJeff Layton 5299f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5309f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5319f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5329f1fafeeSAl Viro nd->root.mnt = NULL; 5339f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5349f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5359f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5369f1fafeeSAl Viro rcu_read_unlock(); 5379f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5389f1fafeeSAl Viro return -ECHILD; 5399f1fafeeSAl Viro } 5409f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5419f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5429f1fafeeSAl Viro mntget(nd->path.mnt); 5439f1fafeeSAl Viro rcu_read_unlock(); 5449f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5459f1fafeeSAl Viro } 5469f1fafeeSAl Viro 54716c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 54839159de2SJeff Layton return 0; 54939159de2SJeff Layton 55016c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 55116c2cd71SAl Viro return 0; 55216c2cd71SAl Viro 55316c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 55416c2cd71SAl Viro return 0; 55516c2cd71SAl Viro 55616c2cd71SAl Viro /* Note: we do not d_invalidate() */ 55734286d66SNick Piggin status = d_revalidate(dentry, nd); 55839159de2SJeff Layton if (status > 0) 55939159de2SJeff Layton return 0; 56039159de2SJeff Layton 56116c2cd71SAl Viro if (!status) 56239159de2SJeff Layton status = -ESTALE; 56316c2cd71SAl Viro 5649f1fafeeSAl Viro path_put(&nd->path); 56539159de2SJeff Layton return status; 56639159de2SJeff Layton } 56739159de2SJeff Layton 56839159de2SJeff Layton /* 569b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 570b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 571b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 5721da177e4SLinus Torvalds * 5731da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 574b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 5751da177e4SLinus Torvalds * complete permission check. 5761da177e4SLinus Torvalds */ 577b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 5781da177e4SLinus Torvalds { 5795909ccaaSLinus Torvalds int ret; 580e795b717SSerge E. Hallyn struct user_namespace *ns = inode_userns(inode); 5811da177e4SLinus Torvalds 582cb9179eaSLinus Torvalds if (inode->i_op->permission) { 583b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 584b74c79e9SNick Piggin } else { 585b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 586b74c79e9SNick Piggin inode->i_op->check_acl); 587cb9179eaSLinus Torvalds } 588b74c79e9SNick Piggin if (likely(!ret)) 5891da177e4SLinus Torvalds goto ok; 590b74c79e9SNick Piggin if (ret == -ECHILD) 59131e6b01fSNick Piggin return ret; 5921da177e4SLinus Torvalds 593e795b717SSerge E. Hallyn if (ns_capable(ns, CAP_DAC_OVERRIDE) || 594e795b717SSerge E. Hallyn ns_capable(ns, CAP_DAC_READ_SEARCH)) 5951da177e4SLinus Torvalds goto ok; 5961da177e4SLinus Torvalds 5975909ccaaSLinus Torvalds return ret; 5981da177e4SLinus Torvalds ok: 599b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 6001da177e4SLinus Torvalds } 6011da177e4SLinus Torvalds 6022a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6032a737871SAl Viro { 604f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 605f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6062a737871SAl Viro } 6072a737871SAl Viro 6086de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6096de88d72SAl Viro 61031e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 61131e6b01fSNick Piggin { 61231e6b01fSNick Piggin if (!nd->root.mnt) { 61331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 614c28cc364SNick Piggin unsigned seq; 615c28cc364SNick Piggin 616c28cc364SNick Piggin do { 617c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 61831e6b01fSNick Piggin nd->root = fs->root; 619c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 620c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 62131e6b01fSNick Piggin } 62231e6b01fSNick Piggin } 62331e6b01fSNick Piggin 624f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6251da177e4SLinus Torvalds { 62631e6b01fSNick Piggin int ret; 62731e6b01fSNick Piggin 6281da177e4SLinus Torvalds if (IS_ERR(link)) 6291da177e4SLinus Torvalds goto fail; 6301da177e4SLinus Torvalds 6311da177e4SLinus Torvalds if (*link == '/') { 6322a737871SAl Viro set_root(nd); 6331d957f9bSJan Blunck path_put(&nd->path); 6342a737871SAl Viro nd->path = nd->root; 6352a737871SAl Viro path_get(&nd->root); 63616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6371da177e4SLinus Torvalds } 63831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 639b4091d5fSChristoph Hellwig 64031e6b01fSNick Piggin ret = link_path_walk(link, nd); 64131e6b01fSNick Piggin return ret; 6421da177e4SLinus Torvalds fail: 6431d957f9bSJan Blunck path_put(&nd->path); 6441da177e4SLinus Torvalds return PTR_ERR(link); 6451da177e4SLinus Torvalds } 6461da177e4SLinus Torvalds 6471d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 648051d3812SIan Kent { 649051d3812SIan Kent dput(path->dentry); 6504ac91378SJan Blunck if (path->mnt != nd->path.mnt) 651051d3812SIan Kent mntput(path->mnt); 652051d3812SIan Kent } 653051d3812SIan Kent 6547b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6557b9337aaSNick Piggin struct nameidata *nd) 656051d3812SIan Kent { 65731e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6584ac91378SJan Blunck dput(nd->path.dentry); 65931e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6604ac91378SJan Blunck mntput(nd->path.mnt); 6619a229683SHuang Shijie } 66231e6b01fSNick Piggin nd->path.mnt = path->mnt; 6634ac91378SJan Blunck nd->path.dentry = path->dentry; 664051d3812SIan Kent } 665051d3812SIan Kent 666574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 667574197e0SAl Viro { 668574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 669574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 670574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 671574197e0SAl Viro path_put(link); 672574197e0SAl Viro } 673574197e0SAl Viro 674def4af30SAl Viro static __always_inline int 675574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6761da177e4SLinus Torvalds { 6771da177e4SLinus Torvalds int error; 6787b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6791da177e4SLinus Torvalds 680844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 681844a3917SAl Viro 6820e794589SAl Viro if (link->mnt == nd->path.mnt) 6830e794589SAl Viro mntget(link->mnt); 6840e794589SAl Viro 685574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 686574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 687574197e0SAl Viro path_put(&nd->path); 688574197e0SAl Viro return -ELOOP; 689574197e0SAl Viro } 690574197e0SAl Viro cond_resched(); 691574197e0SAl Viro current->total_link_count++; 692574197e0SAl Viro 6937b9337aaSNick Piggin touch_atime(link->mnt, dentry); 6941da177e4SLinus Torvalds nd_set_link(nd, NULL); 695cd4e91d3SAl Viro 69636f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 69736f3b4f6SAl Viro if (error) { 69836f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 69936f3b4f6SAl Viro path_put(&nd->path); 70036f3b4f6SAl Viro return error; 70136f3b4f6SAl Viro } 70236f3b4f6SAl Viro 70386acdca1SAl Viro nd->last_type = LAST_BIND; 704def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 705def4af30SAl Viro error = PTR_ERR(*p); 706def4af30SAl Viro if (!IS_ERR(*p)) { 7071da177e4SLinus Torvalds char *s = nd_get_link(nd); 708cc314eefSLinus Torvalds error = 0; 7091da177e4SLinus Torvalds if (s) 7101da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 711bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 71216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 713b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 714b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 715bcda7652SAl Viro /* stepped on a _really_ weird one */ 716bcda7652SAl Viro path_put(&nd->path); 717bcda7652SAl Viro error = -ELOOP; 718bcda7652SAl Viro } 719bcda7652SAl Viro } 7201da177e4SLinus Torvalds } 7211da177e4SLinus Torvalds return error; 7221da177e4SLinus Torvalds } 7231da177e4SLinus Torvalds 72431e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 72531e6b01fSNick Piggin { 72631e6b01fSNick Piggin struct vfsmount *parent; 72731e6b01fSNick Piggin struct dentry *mountpoint; 72831e6b01fSNick Piggin 72931e6b01fSNick Piggin parent = path->mnt->mnt_parent; 73031e6b01fSNick Piggin if (parent == path->mnt) 73131e6b01fSNick Piggin return 0; 73231e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 73331e6b01fSNick Piggin path->dentry = mountpoint; 73431e6b01fSNick Piggin path->mnt = parent; 73531e6b01fSNick Piggin return 1; 73631e6b01fSNick Piggin } 73731e6b01fSNick Piggin 738bab77ebfSAl Viro int follow_up(struct path *path) 7391da177e4SLinus Torvalds { 7401da177e4SLinus Torvalds struct vfsmount *parent; 7411da177e4SLinus Torvalds struct dentry *mountpoint; 74299b7db7bSNick Piggin 74399b7db7bSNick Piggin br_read_lock(vfsmount_lock); 744bab77ebfSAl Viro parent = path->mnt->mnt_parent; 745bab77ebfSAl Viro if (parent == path->mnt) { 74699b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 7471da177e4SLinus Torvalds return 0; 7481da177e4SLinus Torvalds } 7491da177e4SLinus Torvalds mntget(parent); 750bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 75199b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 752bab77ebfSAl Viro dput(path->dentry); 753bab77ebfSAl Viro path->dentry = mountpoint; 754bab77ebfSAl Viro mntput(path->mnt); 755bab77ebfSAl Viro path->mnt = parent; 7561da177e4SLinus Torvalds return 1; 7571da177e4SLinus Torvalds } 7581da177e4SLinus Torvalds 759b5c84bf6SNick Piggin /* 7609875cf80SDavid Howells * Perform an automount 7619875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7629875cf80SDavid Howells * were called with. 7631da177e4SLinus Torvalds */ 7649875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7659875cf80SDavid Howells bool *need_mntput) 76631e6b01fSNick Piggin { 7679875cf80SDavid Howells struct vfsmount *mnt; 768ea5b778aSDavid Howells int err; 7699875cf80SDavid Howells 7709875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7719875cf80SDavid Howells return -EREMOTE; 7729875cf80SDavid Howells 7736f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 7746f45b656SDavid Howells * and this is the terminal part of the path. 7756f45b656SDavid Howells */ 7766f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 7776f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 7786f45b656SDavid Howells 7799875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 7809875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 7819875cf80SDavid Howells * or wants to open the mounted directory. 7829875cf80SDavid Howells * 7839875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 7849875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 7859875cf80SDavid Howells * appended a '/' to the name. 7869875cf80SDavid Howells */ 7879875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 7889875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 7899875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 7909875cf80SDavid Howells return -EISDIR; 7919875cf80SDavid Howells 7929875cf80SDavid Howells current->total_link_count++; 7939875cf80SDavid Howells if (current->total_link_count >= 40) 7949875cf80SDavid Howells return -ELOOP; 7959875cf80SDavid Howells 7969875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7979875cf80SDavid Howells if (IS_ERR(mnt)) { 7989875cf80SDavid Howells /* 7999875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8009875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 8019875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 8029875cf80SDavid Howells * 8039875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 8049875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 8059875cf80SDavid Howells * the path is inaccessible and we should say so. 8069875cf80SDavid Howells */ 8079875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 8089875cf80SDavid Howells return -EREMOTE; 8099875cf80SDavid Howells return PTR_ERR(mnt); 81031e6b01fSNick Piggin } 811ea5b778aSDavid Howells 8129875cf80SDavid Howells if (!mnt) /* mount collision */ 8139875cf80SDavid Howells return 0; 8149875cf80SDavid Howells 81519a167afSAl Viro err = finish_automount(mnt, path); 816ea5b778aSDavid Howells 817ea5b778aSDavid Howells switch (err) { 818ea5b778aSDavid Howells case -EBUSY: 819ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 82019a167afSAl Viro return 0; 821ea5b778aSDavid Howells case 0: 822463ffb2eSAl Viro dput(path->dentry); 8239875cf80SDavid Howells if (*need_mntput) 8249875cf80SDavid Howells mntput(path->mnt); 8259875cf80SDavid Howells path->mnt = mnt; 8269875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 8279875cf80SDavid Howells *need_mntput = true; 8289875cf80SDavid Howells return 0; 82919a167afSAl Viro default: 83019a167afSAl Viro return err; 8319875cf80SDavid Howells } 83219a167afSAl Viro 833ea5b778aSDavid Howells } 8349875cf80SDavid Howells 8359875cf80SDavid Howells /* 8369875cf80SDavid Howells * Handle a dentry that is managed in some way. 837cc53ce53SDavid Howells * - Flagged for transit management (autofs) 8389875cf80SDavid Howells * - Flagged as mountpoint 8399875cf80SDavid Howells * - Flagged as automount point 8409875cf80SDavid Howells * 8419875cf80SDavid Howells * This may only be called in refwalk mode. 8429875cf80SDavid Howells * 8439875cf80SDavid Howells * Serialization is taken care of in namespace.c 8449875cf80SDavid Howells */ 8459875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 8469875cf80SDavid Howells { 8479875cf80SDavid Howells unsigned managed; 8489875cf80SDavid Howells bool need_mntput = false; 8499875cf80SDavid Howells int ret; 8509875cf80SDavid Howells 8519875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8529875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8539875cf80SDavid Howells * the components of that value change under us */ 8549875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8559875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8569875cf80SDavid Howells unlikely(managed != 0)) { 857cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 858cc53ce53SDavid Howells * being held. */ 859cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 860cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 861cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8621aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 863cc53ce53SDavid Howells if (ret < 0) 864cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 865cc53ce53SDavid Howells } 866cc53ce53SDavid Howells 8679875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8689875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8699875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8709875cf80SDavid Howells if (mounted) { 8719875cf80SDavid Howells dput(path->dentry); 8729875cf80SDavid Howells if (need_mntput) 873463ffb2eSAl Viro mntput(path->mnt); 874463ffb2eSAl Viro path->mnt = mounted; 875463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8769875cf80SDavid Howells need_mntput = true; 8779875cf80SDavid Howells continue; 878463ffb2eSAl Viro } 879463ffb2eSAl Viro 8809875cf80SDavid Howells /* Something is mounted on this dentry in another 8819875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8829875cf80SDavid Howells * namespace got unmounted before we managed to get the 8839875cf80SDavid Howells * vfsmount_lock */ 8841da177e4SLinus Torvalds } 8859875cf80SDavid Howells 8869875cf80SDavid Howells /* Handle an automount point */ 8879875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8889875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8899875cf80SDavid Howells if (ret < 0) 8909875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 8919875cf80SDavid Howells continue; 8929875cf80SDavid Howells } 8939875cf80SDavid Howells 8949875cf80SDavid Howells /* We didn't change the current path point */ 8959875cf80SDavid Howells break; 8969875cf80SDavid Howells } 8979875cf80SDavid Howells return 0; 8981da177e4SLinus Torvalds } 8991da177e4SLinus Torvalds 900cc53ce53SDavid Howells int follow_down_one(struct path *path) 9011da177e4SLinus Torvalds { 9021da177e4SLinus Torvalds struct vfsmount *mounted; 9031da177e4SLinus Torvalds 9041c755af4SAl Viro mounted = lookup_mnt(path); 9051da177e4SLinus Torvalds if (mounted) { 9069393bd07SAl Viro dput(path->dentry); 9079393bd07SAl Viro mntput(path->mnt); 9089393bd07SAl Viro path->mnt = mounted; 9099393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9101da177e4SLinus Torvalds return 1; 9111da177e4SLinus Torvalds } 9121da177e4SLinus Torvalds return 0; 9131da177e4SLinus Torvalds } 9141da177e4SLinus Torvalds 91562a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 91662a7375eSIan Kent { 91762a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 91862a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 91962a7375eSIan Kent } 92062a7375eSIan Kent 9219875cf80SDavid Howells /* 922287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 923287548e4SAl Viro * we meet a managed dentry that would need blocking. 9249875cf80SDavid Howells */ 9259875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 926287548e4SAl Viro struct inode **inode) 9279875cf80SDavid Howells { 92862a7375eSIan Kent for (;;) { 9299875cf80SDavid Howells struct vfsmount *mounted; 93062a7375eSIan Kent /* 93162a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 93262a7375eSIan Kent * that wants to block transit. 93362a7375eSIan Kent */ 93462a7375eSIan Kent *inode = path->dentry->d_inode; 935287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 936ab90911fSDavid Howells return false; 93762a7375eSIan Kent 93862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 93962a7375eSIan Kent break; 94062a7375eSIan Kent 9419875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9429875cf80SDavid Howells if (!mounted) 9439875cf80SDavid Howells break; 9449875cf80SDavid Howells path->mnt = mounted; 9459875cf80SDavid Howells path->dentry = mounted->mnt_root; 9469875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 9479875cf80SDavid Howells } 9489875cf80SDavid Howells 9499875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 950287548e4SAl Viro return false; 9519875cf80SDavid Howells return true; 9529875cf80SDavid Howells } 9539875cf80SDavid Howells 954287548e4SAl Viro static void follow_mount_rcu(struct nameidata *nd, struct path *path, 955287548e4SAl Viro struct inode **inode) 956287548e4SAl Viro { 957287548e4SAl Viro for (;;) { 958287548e4SAl Viro struct vfsmount *mounted; 959287548e4SAl Viro *inode = path->dentry->d_inode; 960287548e4SAl Viro 961287548e4SAl Viro if (!d_mountpoint(path->dentry)) 962287548e4SAl Viro break; 963287548e4SAl Viro 964287548e4SAl Viro mounted = __lookup_mnt(path->mnt, path->dentry, 1); 965287548e4SAl Viro if (!mounted) 966287548e4SAl Viro break; 967287548e4SAl Viro path->mnt = mounted; 968287548e4SAl Viro path->dentry = mounted->mnt_root; 969287548e4SAl Viro nd->seq = read_seqcount_begin(&path->dentry->d_seq); 970287548e4SAl Viro } 971287548e4SAl Viro } 972287548e4SAl Viro 97331e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 97431e6b01fSNick Piggin { 97531e6b01fSNick Piggin struct inode *inode = nd->inode; 97631e6b01fSNick Piggin 97731e6b01fSNick Piggin set_root_rcu(nd); 97831e6b01fSNick Piggin 97931e6b01fSNick Piggin while (1) { 98031e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 98131e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 98231e6b01fSNick Piggin break; 98331e6b01fSNick Piggin } 98431e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 98531e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 98631e6b01fSNick Piggin struct dentry *parent = old->d_parent; 98731e6b01fSNick Piggin unsigned seq; 98831e6b01fSNick Piggin 98931e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 99031e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 991ef7562d5SAl Viro goto failed; 99231e6b01fSNick Piggin inode = parent->d_inode; 99331e6b01fSNick Piggin nd->path.dentry = parent; 99431e6b01fSNick Piggin nd->seq = seq; 99531e6b01fSNick Piggin break; 99631e6b01fSNick Piggin } 99731e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 99831e6b01fSNick Piggin break; 99931e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 100031e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 100131e6b01fSNick Piggin } 1002287548e4SAl Viro follow_mount_rcu(nd, &nd->path, &inode); 100331e6b01fSNick Piggin nd->inode = inode; 100431e6b01fSNick Piggin return 0; 1005ef7562d5SAl Viro 1006ef7562d5SAl Viro failed: 1007ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 10085b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1009ef7562d5SAl Viro nd->root.mnt = NULL; 1010ef7562d5SAl Viro rcu_read_unlock(); 1011ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 1012ef7562d5SAl Viro return -ECHILD; 101331e6b01fSNick Piggin } 101431e6b01fSNick Piggin 10159875cf80SDavid Howells /* 1016cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1017cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1018cc53ce53SDavid Howells * caller is permitted to proceed or not. 1019cc53ce53SDavid Howells * 1020cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1021cc53ce53SDavid Howells * being true). 1022cc53ce53SDavid Howells */ 10237cc90cc3SAl Viro int follow_down(struct path *path) 1024cc53ce53SDavid Howells { 1025cc53ce53SDavid Howells unsigned managed; 1026cc53ce53SDavid Howells int ret; 1027cc53ce53SDavid Howells 1028cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1029cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1030cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1031cc53ce53SDavid Howells * being held. 1032cc53ce53SDavid Howells * 1033cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1034cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1035cc53ce53SDavid Howells * other than its daemon the right to mount on its 1036cc53ce53SDavid Howells * superstructure. 1037cc53ce53SDavid Howells * 1038cc53ce53SDavid Howells * The filesystem may sleep at this point. 1039cc53ce53SDavid Howells */ 1040cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1041cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1042cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1043ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 10441aed3e42SAl Viro path->dentry, false); 1045cc53ce53SDavid Howells if (ret < 0) 1046cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1047cc53ce53SDavid Howells } 1048cc53ce53SDavid Howells 1049cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1050cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1051cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1052cc53ce53SDavid Howells if (!mounted) 1053cc53ce53SDavid Howells break; 1054cc53ce53SDavid Howells dput(path->dentry); 1055cc53ce53SDavid Howells mntput(path->mnt); 1056cc53ce53SDavid Howells path->mnt = mounted; 1057cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1058cc53ce53SDavid Howells continue; 1059cc53ce53SDavid Howells } 1060cc53ce53SDavid Howells 1061cc53ce53SDavid Howells /* Don't handle automount points here */ 1062cc53ce53SDavid Howells break; 1063cc53ce53SDavid Howells } 1064cc53ce53SDavid Howells return 0; 1065cc53ce53SDavid Howells } 1066cc53ce53SDavid Howells 1067cc53ce53SDavid Howells /* 10689875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10699875cf80SDavid Howells */ 10709875cf80SDavid Howells static void follow_mount(struct path *path) 10719875cf80SDavid Howells { 10729875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10739875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10749875cf80SDavid Howells if (!mounted) 10759875cf80SDavid Howells break; 10769875cf80SDavid Howells dput(path->dentry); 10779875cf80SDavid Howells mntput(path->mnt); 10789875cf80SDavid Howells path->mnt = mounted; 10799875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10809875cf80SDavid Howells } 10819875cf80SDavid Howells } 10829875cf80SDavid Howells 108331e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10841da177e4SLinus Torvalds { 10852a737871SAl Viro set_root(nd); 1086e518ddb7SAndreas Mohr 10871da177e4SLinus Torvalds while(1) { 10884ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10891da177e4SLinus Torvalds 10902a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10912a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10921da177e4SLinus Torvalds break; 10931da177e4SLinus Torvalds } 10944ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10953088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10963088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10971da177e4SLinus Torvalds dput(old); 10981da177e4SLinus Torvalds break; 10991da177e4SLinus Torvalds } 11003088dd70SAl Viro if (!follow_up(&nd->path)) 11011da177e4SLinus Torvalds break; 11021da177e4SLinus Torvalds } 110379ed0226SAl Viro follow_mount(&nd->path); 110431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11051da177e4SLinus Torvalds } 11061da177e4SLinus Torvalds 11071da177e4SLinus Torvalds /* 1108baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1109baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1110baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1111baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1112baa03890SNick Piggin */ 1113baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1114baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1115baa03890SNick Piggin { 1116baa03890SNick Piggin struct inode *inode = parent->d_inode; 1117baa03890SNick Piggin struct dentry *dentry; 1118baa03890SNick Piggin struct dentry *old; 1119baa03890SNick Piggin 1120baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1121baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1122baa03890SNick Piggin return ERR_PTR(-ENOENT); 1123baa03890SNick Piggin 1124baa03890SNick Piggin dentry = d_alloc(parent, name); 1125baa03890SNick Piggin if (unlikely(!dentry)) 1126baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1127baa03890SNick Piggin 1128baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1129baa03890SNick Piggin if (unlikely(old)) { 1130baa03890SNick Piggin dput(dentry); 1131baa03890SNick Piggin dentry = old; 1132baa03890SNick Piggin } 1133baa03890SNick Piggin return dentry; 1134baa03890SNick Piggin } 1135baa03890SNick Piggin 1136baa03890SNick Piggin /* 11371da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11381da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11391da177e4SLinus Torvalds * It _is_ time-critical. 11401da177e4SLinus Torvalds */ 11411da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 114231e6b01fSNick Piggin struct path *path, struct inode **inode) 11431da177e4SLinus Torvalds { 11444ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 114531e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11465a18fff2SAl Viro int need_reval = 1; 11475a18fff2SAl Viro int status = 1; 11489875cf80SDavid Howells int err; 11499875cf80SDavid Howells 11503cac260aSAl Viro /* 1151b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1152b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1153b04f784eSNick Piggin * do the non-racy lookup, below. 1154b04f784eSNick Piggin */ 115531e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 115631e6b01fSNick Piggin unsigned seq; 115731e6b01fSNick Piggin *inode = nd->inode; 115831e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11595a18fff2SAl Viro if (!dentry) 11605a18fff2SAl Viro goto unlazy; 11615a18fff2SAl Viro 116231e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 116331e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 116431e6b01fSNick Piggin return -ECHILD; 116531e6b01fSNick Piggin nd->seq = seq; 11665a18fff2SAl Viro 116724643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11685a18fff2SAl Viro status = d_revalidate(dentry, nd); 11695a18fff2SAl Viro if (unlikely(status <= 0)) { 11705a18fff2SAl Viro if (status != -ECHILD) 11715a18fff2SAl Viro need_reval = 0; 11725a18fff2SAl Viro goto unlazy; 11735a18fff2SAl Viro } 117424643087SAl Viro } 117531e6b01fSNick Piggin path->mnt = mnt; 117631e6b01fSNick Piggin path->dentry = dentry; 1177287548e4SAl Viro if (likely(__follow_mount_rcu(nd, path, inode))) 11789875cf80SDavid Howells return 0; 11795a18fff2SAl Viro unlazy: 118019660af7SAl Viro if (unlazy_walk(nd, dentry)) 11815a18fff2SAl Viro return -ECHILD; 11825a18fff2SAl Viro } else { 118331e6b01fSNick Piggin dentry = __d_lookup(parent, name); 118424643087SAl Viro } 11855a18fff2SAl Viro 11865a18fff2SAl Viro retry: 11875a18fff2SAl Viro if (unlikely(!dentry)) { 11885a18fff2SAl Viro struct inode *dir = parent->d_inode; 11895a18fff2SAl Viro BUG_ON(nd->inode != dir); 11905a18fff2SAl Viro 11915a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11925a18fff2SAl Viro dentry = d_lookup(parent, name); 11935a18fff2SAl Viro if (likely(!dentry)) { 11945a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 11955a18fff2SAl Viro if (IS_ERR(dentry)) { 11965a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11975a18fff2SAl Viro return PTR_ERR(dentry); 11985a18fff2SAl Viro } 11995a18fff2SAl Viro /* known good */ 12005a18fff2SAl Viro need_reval = 0; 12015a18fff2SAl Viro status = 1; 12025a18fff2SAl Viro } 12035a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12045a18fff2SAl Viro } 12055a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12065a18fff2SAl Viro status = d_revalidate(dentry, nd); 12075a18fff2SAl Viro if (unlikely(status <= 0)) { 12085a18fff2SAl Viro if (status < 0) { 12095a18fff2SAl Viro dput(dentry); 12105a18fff2SAl Viro return status; 12115a18fff2SAl Viro } 12125a18fff2SAl Viro if (!d_invalidate(dentry)) { 12135a18fff2SAl Viro dput(dentry); 12145a18fff2SAl Viro dentry = NULL; 12155a18fff2SAl Viro need_reval = 1; 12165a18fff2SAl Viro goto retry; 12175a18fff2SAl Viro } 12185a18fff2SAl Viro } 12195a18fff2SAl Viro 12201da177e4SLinus Torvalds path->mnt = mnt; 12211da177e4SLinus Torvalds path->dentry = dentry; 12229875cf80SDavid Howells err = follow_managed(path, nd->flags); 122389312214SIan Kent if (unlikely(err < 0)) { 122489312214SIan Kent path_put_conditional(path, nd); 12259875cf80SDavid Howells return err; 122689312214SIan Kent } 122731e6b01fSNick Piggin *inode = path->dentry->d_inode; 12281da177e4SLinus Torvalds return 0; 12291da177e4SLinus Torvalds } 12301da177e4SLinus Torvalds 123152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 123252094c8aSAl Viro { 123352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 123452094c8aSAl Viro int err = exec_permission(nd->inode, IPERM_FLAG_RCU); 123552094c8aSAl Viro if (err != -ECHILD) 123652094c8aSAl Viro return err; 123719660af7SAl Viro if (unlazy_walk(nd, NULL)) 123852094c8aSAl Viro return -ECHILD; 123952094c8aSAl Viro } 124052094c8aSAl Viro return exec_permission(nd->inode, 0); 124152094c8aSAl Viro } 124252094c8aSAl Viro 12439856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12449856fa1bSAl Viro { 12459856fa1bSAl Viro if (type == LAST_DOTDOT) { 12469856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12479856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12489856fa1bSAl Viro return -ECHILD; 12499856fa1bSAl Viro } else 12509856fa1bSAl Viro follow_dotdot(nd); 12519856fa1bSAl Viro } 12529856fa1bSAl Viro return 0; 12539856fa1bSAl Viro } 12549856fa1bSAl Viro 1255951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1256951361f9SAl Viro { 1257951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1258951361f9SAl Viro path_put(&nd->path); 1259951361f9SAl Viro } else { 1260951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12615b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1262951361f9SAl Viro nd->root.mnt = NULL; 1263951361f9SAl Viro rcu_read_unlock(); 1264951361f9SAl Viro br_read_unlock(vfsmount_lock); 1265951361f9SAl Viro } 1266951361f9SAl Viro } 1267951361f9SAl Viro 1268ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1269ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1270ce57dfc1SAl Viro { 1271ce57dfc1SAl Viro struct inode *inode; 1272ce57dfc1SAl Viro int err; 1273ce57dfc1SAl Viro /* 1274ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1275ce57dfc1SAl Viro * to be able to know about the current root directory and 1276ce57dfc1SAl Viro * parent relationships. 1277ce57dfc1SAl Viro */ 1278ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1279ce57dfc1SAl Viro return handle_dots(nd, type); 1280ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1281ce57dfc1SAl Viro if (unlikely(err)) { 1282ce57dfc1SAl Viro terminate_walk(nd); 1283ce57dfc1SAl Viro return err; 1284ce57dfc1SAl Viro } 1285ce57dfc1SAl Viro if (!inode) { 1286ce57dfc1SAl Viro path_to_nameidata(path, nd); 1287ce57dfc1SAl Viro terminate_walk(nd); 1288ce57dfc1SAl Viro return -ENOENT; 1289ce57dfc1SAl Viro } 1290ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 129119660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 129219660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 129319660af7SAl Viro terminate_walk(nd); 1294ce57dfc1SAl Viro return -ECHILD; 129519660af7SAl Viro } 129619660af7SAl Viro } 1297ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1298ce57dfc1SAl Viro return 1; 1299ce57dfc1SAl Viro } 1300ce57dfc1SAl Viro path_to_nameidata(path, nd); 1301ce57dfc1SAl Viro nd->inode = inode; 1302ce57dfc1SAl Viro return 0; 1303ce57dfc1SAl Viro } 1304ce57dfc1SAl Viro 13051da177e4SLinus Torvalds /* 1306b356379aSAl Viro * This limits recursive symlink follows to 8, while 1307b356379aSAl Viro * limiting consecutive symlinks to 40. 1308b356379aSAl Viro * 1309b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1310b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1311b356379aSAl Viro */ 1312b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1313b356379aSAl Viro { 1314b356379aSAl Viro int res; 1315b356379aSAl Viro 1316b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1317b356379aSAl Viro path_put_conditional(path, nd); 1318b356379aSAl Viro path_put(&nd->path); 1319b356379aSAl Viro return -ELOOP; 1320b356379aSAl Viro } 13211a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1322b356379aSAl Viro 1323b356379aSAl Viro nd->depth++; 1324b356379aSAl Viro current->link_count++; 1325b356379aSAl Viro 1326b356379aSAl Viro do { 1327b356379aSAl Viro struct path link = *path; 1328b356379aSAl Viro void *cookie; 1329574197e0SAl Viro 1330574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1331b356379aSAl Viro if (!res) 1332b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1333b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1334574197e0SAl Viro put_link(nd, &link, cookie); 1335b356379aSAl Viro } while (res > 0); 1336b356379aSAl Viro 1337b356379aSAl Viro current->link_count--; 1338b356379aSAl Viro nd->depth--; 1339b356379aSAl Viro return res; 1340b356379aSAl Viro } 1341b356379aSAl Viro 1342b356379aSAl Viro /* 13431da177e4SLinus Torvalds * Name resolution. 1344ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1345ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13461da177e4SLinus Torvalds * 1347ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1348ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13491da177e4SLinus Torvalds */ 13506de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13511da177e4SLinus Torvalds { 13521da177e4SLinus Torvalds struct path next; 13531da177e4SLinus Torvalds int err; 13541da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13551da177e4SLinus Torvalds 13561da177e4SLinus Torvalds while (*name=='/') 13571da177e4SLinus Torvalds name++; 13581da177e4SLinus Torvalds if (!*name) 1359086e183aSAl Viro return 0; 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13621da177e4SLinus Torvalds for(;;) { 13631da177e4SLinus Torvalds unsigned long hash; 13641da177e4SLinus Torvalds struct qstr this; 13651da177e4SLinus Torvalds unsigned int c; 1366fe479a58SAl Viro int type; 13671da177e4SLinus Torvalds 1368cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 136952094c8aSAl Viro 137052094c8aSAl Viro err = may_lookup(nd); 13711da177e4SLinus Torvalds if (err) 13721da177e4SLinus Torvalds break; 13731da177e4SLinus Torvalds 13741da177e4SLinus Torvalds this.name = name; 13751da177e4SLinus Torvalds c = *(const unsigned char *)name; 13761da177e4SLinus Torvalds 13771da177e4SLinus Torvalds hash = init_name_hash(); 13781da177e4SLinus Torvalds do { 13791da177e4SLinus Torvalds name++; 13801da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13811da177e4SLinus Torvalds c = *(const unsigned char *)name; 13821da177e4SLinus Torvalds } while (c && (c != '/')); 13831da177e4SLinus Torvalds this.len = name - (const char *) this.name; 13841da177e4SLinus Torvalds this.hash = end_name_hash(hash); 13851da177e4SLinus Torvalds 1386fe479a58SAl Viro type = LAST_NORM; 1387fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1388fe479a58SAl Viro case 2: 138916c2cd71SAl Viro if (this.name[1] == '.') { 1390fe479a58SAl Viro type = LAST_DOTDOT; 139116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 139216c2cd71SAl Viro } 1393fe479a58SAl Viro break; 1394fe479a58SAl Viro case 1: 1395fe479a58SAl Viro type = LAST_DOT; 1396fe479a58SAl Viro } 13975a202bcdSAl Viro if (likely(type == LAST_NORM)) { 13985a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 139916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14005a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14015a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14025a202bcdSAl Viro &this); 14035a202bcdSAl Viro if (err < 0) 14045a202bcdSAl Viro break; 14055a202bcdSAl Viro } 14065a202bcdSAl Viro } 1407fe479a58SAl Viro 14081da177e4SLinus Torvalds /* remove trailing slashes? */ 14091da177e4SLinus Torvalds if (!c) 14101da177e4SLinus Torvalds goto last_component; 14111da177e4SLinus Torvalds while (*++name == '/'); 14121da177e4SLinus Torvalds if (!*name) 1413b356379aSAl Viro goto last_component; 14141da177e4SLinus Torvalds 1415ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1416ce57dfc1SAl Viro if (err < 0) 1417ce57dfc1SAl Viro return err; 1418fe479a58SAl Viro 1419ce57dfc1SAl Viro if (err) { 1420b356379aSAl Viro err = nested_symlink(&next, nd); 14211da177e4SLinus Torvalds if (err) 1422a7472babSAl Viro return err; 142331e6b01fSNick Piggin } 14241da177e4SLinus Torvalds err = -ENOTDIR; 142531e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14261da177e4SLinus Torvalds break; 14271da177e4SLinus Torvalds continue; 14281da177e4SLinus Torvalds /* here ends the main loop */ 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds last_component: 1431f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1432f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1433ce57dfc1SAl Viro nd->last = this; 1434ce57dfc1SAl Viro nd->last_type = type; 1435ce57dfc1SAl Viro return 0; 1436ce57dfc1SAl Viro } 1437951361f9SAl Viro terminate_walk(nd); 14381da177e4SLinus Torvalds return err; 14391da177e4SLinus Torvalds } 14401da177e4SLinus Torvalds 144170e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 144270e9b357SAl Viro struct nameidata *nd, struct file **fp) 144331e6b01fSNick Piggin { 144431e6b01fSNick Piggin int retval = 0; 144531e6b01fSNick Piggin int fput_needed; 144631e6b01fSNick Piggin struct file *file; 144731e6b01fSNick Piggin 144831e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 144916c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 145031e6b01fSNick Piggin nd->depth = 0; 14515b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14525b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 145373d049a4SAl Viro if (*name) { 14545b6ca027SAl Viro if (!inode->i_op->lookup) 14555b6ca027SAl Viro return -ENOTDIR; 14565b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14575b6ca027SAl Viro if (retval) 14585b6ca027SAl Viro return retval; 145973d049a4SAl Viro } 14605b6ca027SAl Viro nd->path = nd->root; 14615b6ca027SAl Viro nd->inode = inode; 14625b6ca027SAl Viro if (flags & LOOKUP_RCU) { 14635b6ca027SAl Viro br_read_lock(vfsmount_lock); 14645b6ca027SAl Viro rcu_read_lock(); 14655b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 14665b6ca027SAl Viro } else { 14675b6ca027SAl Viro path_get(&nd->path); 14685b6ca027SAl Viro } 14695b6ca027SAl Viro return 0; 14705b6ca027SAl Viro } 14715b6ca027SAl Viro 147231e6b01fSNick Piggin nd->root.mnt = NULL; 147331e6b01fSNick Piggin 147431e6b01fSNick Piggin if (*name=='/') { 1475e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 147631e6b01fSNick Piggin br_read_lock(vfsmount_lock); 147731e6b01fSNick Piggin rcu_read_lock(); 1478e41f7d4eSAl Viro set_root_rcu(nd); 1479e41f7d4eSAl Viro } else { 1480e41f7d4eSAl Viro set_root(nd); 1481e41f7d4eSAl Viro path_get(&nd->root); 1482e41f7d4eSAl Viro } 148331e6b01fSNick Piggin nd->path = nd->root; 148431e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1485e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 148631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1487c28cc364SNick Piggin unsigned seq; 148831e6b01fSNick Piggin 148931e6b01fSNick Piggin br_read_lock(vfsmount_lock); 149031e6b01fSNick Piggin rcu_read_lock(); 149131e6b01fSNick Piggin 1492c28cc364SNick Piggin do { 1493c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 149431e6b01fSNick Piggin nd->path = fs->pwd; 1495c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1496c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1497e41f7d4eSAl Viro } else { 1498e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1499e41f7d4eSAl Viro } 150031e6b01fSNick Piggin } else { 150131e6b01fSNick Piggin struct dentry *dentry; 150231e6b01fSNick Piggin 15031abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 150431e6b01fSNick Piggin retval = -EBADF; 150531e6b01fSNick Piggin if (!file) 150631e6b01fSNick Piggin goto out_fail; 150731e6b01fSNick Piggin 150831e6b01fSNick Piggin dentry = file->f_path.dentry; 150931e6b01fSNick Piggin 1510f52e0c11SAl Viro if (*name) { 151131e6b01fSNick Piggin retval = -ENOTDIR; 151231e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 151331e6b01fSNick Piggin goto fput_fail; 151431e6b01fSNick Piggin 151531e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 151631e6b01fSNick Piggin if (retval) 151731e6b01fSNick Piggin goto fput_fail; 1518f52e0c11SAl Viro } 151931e6b01fSNick Piggin 152031e6b01fSNick Piggin nd->path = file->f_path; 1521e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 152231e6b01fSNick Piggin if (fput_needed) 152370e9b357SAl Viro *fp = file; 1524c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 152531e6b01fSNick Piggin br_read_lock(vfsmount_lock); 152631e6b01fSNick Piggin rcu_read_lock(); 15275590ff0dSUlrich Drepper } else { 15285dd784d0SJan Blunck path_get(&file->f_path); 15295590ff0dSUlrich Drepper fput_light(file, fput_needed); 15301da177e4SLinus Torvalds } 1531e41f7d4eSAl Viro } 1532e41f7d4eSAl Viro 153331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15349b4a9b14SAl Viro return 0; 15352dfdd266SJosef 'Jeff' Sipek 15369b4a9b14SAl Viro fput_fail: 15379b4a9b14SAl Viro fput_light(file, fput_needed); 15389b4a9b14SAl Viro out_fail: 15399b4a9b14SAl Viro return retval; 15409b4a9b14SAl Viro } 15419b4a9b14SAl Viro 1542bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1543bd92d7feSAl Viro { 1544bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1545bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1546bd92d7feSAl Viro 1547bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1548bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1549bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1550bd92d7feSAl Viro } 1551bd92d7feSAl Viro 15529b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1553ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15549b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15559b4a9b14SAl Viro { 155670e9b357SAl Viro struct file *base = NULL; 1557bd92d7feSAl Viro struct path path; 1558bd92d7feSAl Viro int err; 155931e6b01fSNick Piggin 156031e6b01fSNick Piggin /* 156131e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 156231e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 156331e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 156431e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 156531e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 156631e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 156731e6b01fSNick Piggin * analogue, foo_rcu(). 156831e6b01fSNick Piggin * 156931e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 157031e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 157131e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 157231e6b01fSNick Piggin * be able to complete). 157331e6b01fSNick Piggin */ 1574bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1575ee0827cdSAl Viro 1576bd92d7feSAl Viro if (unlikely(err)) 1577bd92d7feSAl Viro return err; 1578ee0827cdSAl Viro 1579ee0827cdSAl Viro current->total_link_count = 0; 1580bd92d7feSAl Viro err = link_path_walk(name, nd); 1581bd92d7feSAl Viro 1582bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1583bd92d7feSAl Viro err = lookup_last(nd, &path); 1584bd92d7feSAl Viro while (err > 0) { 1585bd92d7feSAl Viro void *cookie; 1586bd92d7feSAl Viro struct path link = path; 1587bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1588574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1589bd92d7feSAl Viro if (!err) 1590bd92d7feSAl Viro err = lookup_last(nd, &path); 1591574197e0SAl Viro put_link(nd, &link, cookie); 1592bd92d7feSAl Viro } 1593bd92d7feSAl Viro } 1594ee0827cdSAl Viro 15959f1fafeeSAl Viro if (!err) 15969f1fafeeSAl Viro err = complete_walk(nd); 1597bd92d7feSAl Viro 1598bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1599bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1600bd92d7feSAl Viro path_put(&nd->path); 1601bd23a539SAl Viro err = -ENOTDIR; 1602bd92d7feSAl Viro } 1603bd92d7feSAl Viro } 160416c2cd71SAl Viro 160570e9b357SAl Viro if (base) 160670e9b357SAl Viro fput(base); 1607ee0827cdSAl Viro 16085b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 160931e6b01fSNick Piggin path_put(&nd->root); 161031e6b01fSNick Piggin nd->root.mnt = NULL; 161131e6b01fSNick Piggin } 1612bd92d7feSAl Viro return err; 161331e6b01fSNick Piggin } 161431e6b01fSNick Piggin 1615ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1616ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1617ee0827cdSAl Viro { 1618ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1619ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1620ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1621ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1622ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1623ee0827cdSAl Viro 162431e6b01fSNick Piggin if (likely(!retval)) { 162531e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 162631e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 162731e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 162831e6b01fSNick Piggin } 162931e6b01fSNick Piggin } 1630170aa3d0SUlrich Drepper return retval; 16311da177e4SLinus Torvalds } 16321da177e4SLinus Torvalds 1633c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16345590ff0dSUlrich Drepper { 1635c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16365590ff0dSUlrich Drepper } 16375590ff0dSUlrich Drepper 1638d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1639d1811465SAl Viro { 1640d1811465SAl Viro struct nameidata nd; 1641d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1642d1811465SAl Viro if (!res) 1643d1811465SAl Viro *path = nd.path; 1644d1811465SAl Viro return res; 1645d1811465SAl Viro } 1646d1811465SAl Viro 164716f18200SJosef 'Jeff' Sipek /** 164816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 164916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 165016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 165116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 165216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 165316f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 165416f18200SJosef 'Jeff' Sipek */ 165516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 165616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 165716f18200SJosef 'Jeff' Sipek struct nameidata *nd) 165816f18200SJosef 'Jeff' Sipek { 16595b6ca027SAl Viro nd->root.dentry = dentry; 16605b6ca027SAl Viro nd->root.mnt = mnt; 16615b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 16625b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 166316f18200SJosef 'Jeff' Sipek } 166416f18200SJosef 'Jeff' Sipek 1665eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1666eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16671da177e4SLinus Torvalds { 166881fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16691da177e4SLinus Torvalds struct dentry *dentry; 16701da177e4SLinus Torvalds int err; 16711da177e4SLinus Torvalds 1672b74c79e9SNick Piggin err = exec_permission(inode, 0); 167381fca444SChristoph Hellwig if (err) 167481fca444SChristoph Hellwig return ERR_PTR(err); 16751da177e4SLinus Torvalds 16761da177e4SLinus Torvalds /* 1677b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1678b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1679b04f784eSNick Piggin * a double lookup. 16806e6b1bd1SAl Viro */ 16816e6b1bd1SAl Viro dentry = d_lookup(base, name); 16826e6b1bd1SAl Viro 1683fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 16846e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 16856e6b1bd1SAl Viro 16861da177e4SLinus Torvalds if (!dentry) 1687baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 16885a202bcdSAl Viro 16891da177e4SLinus Torvalds return dentry; 16901da177e4SLinus Torvalds } 16911da177e4SLinus Torvalds 1692057f6c01SJames Morris /* 1693057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1694057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1695057f6c01SJames Morris * SMP-safe. 1696057f6c01SJames Morris */ 1697a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 16981da177e4SLinus Torvalds { 16994ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17001da177e4SLinus Torvalds } 17011da177e4SLinus Torvalds 1702eead1911SChristoph Hellwig /** 1703a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1704eead1911SChristoph Hellwig * @name: pathname component to lookup 1705eead1911SChristoph Hellwig * @base: base directory to lookup from 1706eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1707eead1911SChristoph Hellwig * 1708a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1709a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1710eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1711eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1712eead1911SChristoph Hellwig */ 1713057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1714057f6c01SJames Morris { 1715057f6c01SJames Morris struct qstr this; 17166a96ba54SAl Viro unsigned long hash; 17176a96ba54SAl Viro unsigned int c; 1718057f6c01SJames Morris 17192f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17202f9092e1SDavid Woodhouse 17216a96ba54SAl Viro this.name = name; 17226a96ba54SAl Viro this.len = len; 17236a96ba54SAl Viro if (!len) 17246a96ba54SAl Viro return ERR_PTR(-EACCES); 17256a96ba54SAl Viro 17266a96ba54SAl Viro hash = init_name_hash(); 17276a96ba54SAl Viro while (len--) { 17286a96ba54SAl Viro c = *(const unsigned char *)name++; 17296a96ba54SAl Viro if (c == '/' || c == '\0') 17306a96ba54SAl Viro return ERR_PTR(-EACCES); 17316a96ba54SAl Viro hash = partial_name_hash(c, hash); 17326a96ba54SAl Viro } 17336a96ba54SAl Viro this.hash = end_name_hash(hash); 17345a202bcdSAl Viro /* 17355a202bcdSAl Viro * See if the low-level filesystem might want 17365a202bcdSAl Viro * to use its own hash.. 17375a202bcdSAl Viro */ 17385a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17395a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17405a202bcdSAl Viro if (err < 0) 17415a202bcdSAl Viro return ERR_PTR(err); 17425a202bcdSAl Viro } 1743eead1911SChristoph Hellwig 174449705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1745057f6c01SJames Morris } 1746057f6c01SJames Morris 17472d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 17482d8f3038SAl Viro struct path *path) 17491da177e4SLinus Torvalds { 17502d8f3038SAl Viro struct nameidata nd; 1751f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 17521da177e4SLinus Torvalds int err = PTR_ERR(tmp); 17531da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 17542d8f3038SAl Viro 17552d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 17562d8f3038SAl Viro 17572d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 17581da177e4SLinus Torvalds putname(tmp); 17592d8f3038SAl Viro if (!err) 17602d8f3038SAl Viro *path = nd.path; 17611da177e4SLinus Torvalds } 17621da177e4SLinus Torvalds return err; 17631da177e4SLinus Torvalds } 17641da177e4SLinus Torvalds 17652ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 17662ad94ae6SAl Viro struct nameidata *nd, char **name) 17672ad94ae6SAl Viro { 17682ad94ae6SAl Viro char *s = getname(path); 17692ad94ae6SAl Viro int error; 17702ad94ae6SAl Viro 17712ad94ae6SAl Viro if (IS_ERR(s)) 17722ad94ae6SAl Viro return PTR_ERR(s); 17732ad94ae6SAl Viro 17742ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 17752ad94ae6SAl Viro if (error) 17762ad94ae6SAl Viro putname(s); 17772ad94ae6SAl Viro else 17782ad94ae6SAl Viro *name = s; 17792ad94ae6SAl Viro 17802ad94ae6SAl Viro return error; 17812ad94ae6SAl Viro } 17822ad94ae6SAl Viro 17831da177e4SLinus Torvalds /* 17841da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 17851da177e4SLinus Torvalds * minimal. 17861da177e4SLinus Torvalds */ 17871da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 17881da177e4SLinus Torvalds { 1789da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1790da9592edSDavid Howells 17911da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 17921da177e4SLinus Torvalds return 0; 1793e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1794e795b717SSerge E. Hallyn goto other_userns; 1795da9592edSDavid Howells if (inode->i_uid == fsuid) 17961da177e4SLinus Torvalds return 0; 1797da9592edSDavid Howells if (dir->i_uid == fsuid) 17981da177e4SLinus Torvalds return 0; 1799e795b717SSerge E. Hallyn 1800e795b717SSerge E. Hallyn other_userns: 1801e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 18021da177e4SLinus Torvalds } 18031da177e4SLinus Torvalds 18041da177e4SLinus Torvalds /* 18051da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18061da177e4SLinus Torvalds * whether the type of victim is right. 18071da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18081da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18091da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18101da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18111da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18121da177e4SLinus Torvalds * a. be owner of dir, or 18131da177e4SLinus Torvalds * b. be owner of victim, or 18141da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18151da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18161da177e4SLinus Torvalds * links pointing to it. 18171da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18181da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18191da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18201da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18211da177e4SLinus Torvalds * nfs_async_unlink(). 18221da177e4SLinus Torvalds */ 1823858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18241da177e4SLinus Torvalds { 18251da177e4SLinus Torvalds int error; 18261da177e4SLinus Torvalds 18271da177e4SLinus Torvalds if (!victim->d_inode) 18281da177e4SLinus Torvalds return -ENOENT; 18291da177e4SLinus Torvalds 18301da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1831cccc6bbaSAl Viro audit_inode_child(victim, dir); 18321da177e4SLinus Torvalds 1833f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18341da177e4SLinus Torvalds if (error) 18351da177e4SLinus Torvalds return error; 18361da177e4SLinus Torvalds if (IS_APPEND(dir)) 18371da177e4SLinus Torvalds return -EPERM; 18381da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1839f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18401da177e4SLinus Torvalds return -EPERM; 18411da177e4SLinus Torvalds if (isdir) { 18421da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18431da177e4SLinus Torvalds return -ENOTDIR; 18441da177e4SLinus Torvalds if (IS_ROOT(victim)) 18451da177e4SLinus Torvalds return -EBUSY; 18461da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18471da177e4SLinus Torvalds return -EISDIR; 18481da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18491da177e4SLinus Torvalds return -ENOENT; 18501da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 18511da177e4SLinus Torvalds return -EBUSY; 18521da177e4SLinus Torvalds return 0; 18531da177e4SLinus Torvalds } 18541da177e4SLinus Torvalds 18551da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 18561da177e4SLinus Torvalds * dir. 18571da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 18581da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 18591da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 18601da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 18611da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 18621da177e4SLinus Torvalds */ 1863a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 18641da177e4SLinus Torvalds { 18651da177e4SLinus Torvalds if (child->d_inode) 18661da177e4SLinus Torvalds return -EEXIST; 18671da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18681da177e4SLinus Torvalds return -ENOENT; 1869f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 18701da177e4SLinus Torvalds } 18711da177e4SLinus Torvalds 18721da177e4SLinus Torvalds /* 18731da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 18741da177e4SLinus Torvalds */ 18751da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 18761da177e4SLinus Torvalds { 18771da177e4SLinus Torvalds struct dentry *p; 18781da177e4SLinus Torvalds 18791da177e4SLinus Torvalds if (p1 == p2) { 1880f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 18811da177e4SLinus Torvalds return NULL; 18821da177e4SLinus Torvalds } 18831da177e4SLinus Torvalds 1884a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18851da177e4SLinus Torvalds 1886e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1887e2761a11SOGAWA Hirofumi if (p) { 1888f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1889f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 18901da177e4SLinus Torvalds return p; 18911da177e4SLinus Torvalds } 18921da177e4SLinus Torvalds 1893e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1894e2761a11SOGAWA Hirofumi if (p) { 1895f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1896f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 18971da177e4SLinus Torvalds return p; 18981da177e4SLinus Torvalds } 18991da177e4SLinus Torvalds 1900f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1901f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19021da177e4SLinus Torvalds return NULL; 19031da177e4SLinus Torvalds } 19041da177e4SLinus Torvalds 19051da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19061da177e4SLinus Torvalds { 19071b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19081da177e4SLinus Torvalds if (p1 != p2) { 19091b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1910a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19111da177e4SLinus Torvalds } 19121da177e4SLinus Torvalds } 19131da177e4SLinus Torvalds 19141da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19151da177e4SLinus Torvalds struct nameidata *nd) 19161da177e4SLinus Torvalds { 1917a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19181da177e4SLinus Torvalds 19191da177e4SLinus Torvalds if (error) 19201da177e4SLinus Torvalds return error; 19211da177e4SLinus Torvalds 1922acfa4380SAl Viro if (!dir->i_op->create) 19231da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19241da177e4SLinus Torvalds mode &= S_IALLUGO; 19251da177e4SLinus Torvalds mode |= S_IFREG; 19261da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19271da177e4SLinus Torvalds if (error) 19281da177e4SLinus Torvalds return error; 19291da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1930a74574aaSStephen Smalley if (!error) 1931f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19321da177e4SLinus Torvalds return error; 19331da177e4SLinus Torvalds } 19341da177e4SLinus Torvalds 193573d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19361da177e4SLinus Torvalds { 19373fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19381da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19391da177e4SLinus Torvalds int error; 19401da177e4SLinus Torvalds 1941bcda7652SAl Viro /* O_PATH? */ 1942bcda7652SAl Viro if (!acc_mode) 1943bcda7652SAl Viro return 0; 1944bcda7652SAl Viro 19451da177e4SLinus Torvalds if (!inode) 19461da177e4SLinus Torvalds return -ENOENT; 19471da177e4SLinus Torvalds 1948c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1949c8fe8f30SChristoph Hellwig case S_IFLNK: 19501da177e4SLinus Torvalds return -ELOOP; 1951c8fe8f30SChristoph Hellwig case S_IFDIR: 1952c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 19531da177e4SLinus Torvalds return -EISDIR; 1954c8fe8f30SChristoph Hellwig break; 1955c8fe8f30SChristoph Hellwig case S_IFBLK: 1956c8fe8f30SChristoph Hellwig case S_IFCHR: 19573fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 19581da177e4SLinus Torvalds return -EACCES; 1959c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1960c8fe8f30SChristoph Hellwig case S_IFIFO: 1961c8fe8f30SChristoph Hellwig case S_IFSOCK: 19621da177e4SLinus Torvalds flag &= ~O_TRUNC; 1963c8fe8f30SChristoph Hellwig break; 19644a3fd211SDave Hansen } 1965b41572e9SDave Hansen 19663fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1967b41572e9SDave Hansen if (error) 1968b41572e9SDave Hansen return error; 19696146f0d5SMimi Zohar 19701da177e4SLinus Torvalds /* 19711da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 19721da177e4SLinus Torvalds */ 19731da177e4SLinus Torvalds if (IS_APPEND(inode)) { 19748737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 19757715b521SAl Viro return -EPERM; 19761da177e4SLinus Torvalds if (flag & O_TRUNC) 19777715b521SAl Viro return -EPERM; 19781da177e4SLinus Torvalds } 19791da177e4SLinus Torvalds 19801da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 19812e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 19827715b521SAl Viro return -EPERM; 19831da177e4SLinus Torvalds 19841da177e4SLinus Torvalds /* 19851da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 19861da177e4SLinus Torvalds */ 1987b65a9cfcSAl Viro return break_lease(inode, flag); 19887715b521SAl Viro } 19897715b521SAl Viro 1990e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 19917715b521SAl Viro { 1992e1181ee6SJeff Layton struct path *path = &filp->f_path; 19937715b521SAl Viro struct inode *inode = path->dentry->d_inode; 19947715b521SAl Viro int error = get_write_access(inode); 19951da177e4SLinus Torvalds if (error) 19967715b521SAl Viro return error; 19971da177e4SLinus Torvalds /* 19981da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 19991da177e4SLinus Torvalds */ 20001da177e4SLinus Torvalds error = locks_verify_locked(inode); 2001be6d3e56SKentaro Takeda if (!error) 2002ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20031da177e4SLinus Torvalds if (!error) { 20047715b521SAl Viro error = do_truncate(path->dentry, 0, 2005d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2006e1181ee6SJeff Layton filp); 20071da177e4SLinus Torvalds } 20081da177e4SLinus Torvalds put_write_access(inode); 2009acd0c935SMimi Zohar return error; 20101da177e4SLinus Torvalds } 20111da177e4SLinus Torvalds 2012d57999e1SDave Hansen /* 2013d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2014d57999e1SDave Hansen * 00 - read-only 2015d57999e1SDave Hansen * 01 - write-only 2016d57999e1SDave Hansen * 10 - read-write 2017d57999e1SDave Hansen * 11 - special 2018d57999e1SDave Hansen * it is changed into 2019d57999e1SDave Hansen * 00 - no permissions needed 2020d57999e1SDave Hansen * 01 - read-permission 2021d57999e1SDave Hansen * 10 - write-permission 2022d57999e1SDave Hansen * 11 - read-write 2023d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2024d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2025d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2026d57999e1SDave Hansen * later). 2027d57999e1SDave Hansen * 2028d57999e1SDave Hansen */ 2029d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2030d57999e1SDave Hansen { 2031d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2032d57999e1SDave Hansen flag++; 2033d57999e1SDave Hansen return flag; 2034d57999e1SDave Hansen } 2035d57999e1SDave Hansen 203631e6b01fSNick Piggin /* 2037fe2d35ffSAl Viro * Handle the last step of open() 203831e6b01fSNick Piggin */ 2039fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2040c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2041fb1cc555SAl Viro { 2042a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20436c0d46c4SAl Viro struct dentry *dentry; 2044ca344a89SAl Viro int open_flag = op->open_flag; 20456c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2046ca344a89SAl Viro int want_write = 0; 2047bcda7652SAl Viro int acc_mode = op->acc_mode; 2048fb1cc555SAl Viro struct file *filp; 204916c2cd71SAl Viro int error; 2050fb1cc555SAl Viro 2051c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2052c3e380b0SAl Viro nd->flags |= op->intent; 2053c3e380b0SAl Viro 20541f36f774SAl Viro switch (nd->last_type) { 20551f36f774SAl Viro case LAST_DOTDOT: 2056176306f5SNeil Brown case LAST_DOT: 2057fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2058fe2d35ffSAl Viro if (error) 2059fe2d35ffSAl Viro return ERR_PTR(error); 20601f36f774SAl Viro /* fallthrough */ 20611f36f774SAl Viro case LAST_ROOT: 20629f1fafeeSAl Viro error = complete_walk(nd); 206316c2cd71SAl Viro if (error) 20649f1fafeeSAl Viro return ERR_PTR(error); 2065fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2066ca344a89SAl Viro if (open_flag & O_CREAT) { 206716c2cd71SAl Viro error = -EISDIR; 20681f36f774SAl Viro goto exit; 2069fe2d35ffSAl Viro } 2070fe2d35ffSAl Viro goto ok; 20711f36f774SAl Viro case LAST_BIND: 20729f1fafeeSAl Viro error = complete_walk(nd); 207316c2cd71SAl Viro if (error) 20749f1fafeeSAl Viro return ERR_PTR(error); 20751f36f774SAl Viro audit_inode(pathname, dir); 20761f36f774SAl Viro goto ok; 20771f36f774SAl Viro } 2078a2c36b45SAl Viro 2079ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2080bcda7652SAl Viro int symlink_ok = 0; 2081fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2082fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2083bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2084bcda7652SAl Viro symlink_ok = 1; 2085fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2086ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2087ce57dfc1SAl Viro !symlink_ok); 2088ce57dfc1SAl Viro if (error < 0) 2089fe2d35ffSAl Viro return ERR_PTR(error); 2090ce57dfc1SAl Viro if (error) /* symlink */ 2091fe2d35ffSAl Viro return NULL; 2092fe2d35ffSAl Viro /* sayonara */ 20939f1fafeeSAl Viro error = complete_walk(nd); 20949f1fafeeSAl Viro if (error) 2095fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2096fe2d35ffSAl Viro 2097fe2d35ffSAl Viro error = -ENOTDIR; 2098fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2099ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2100fe2d35ffSAl Viro goto exit; 2101fe2d35ffSAl Viro } 2102fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2103fe2d35ffSAl Viro goto ok; 2104fe2d35ffSAl Viro } 2105fe2d35ffSAl Viro 2106fe2d35ffSAl Viro /* create side of things */ 21079f1fafeeSAl Viro error = complete_walk(nd); 21089f1fafeeSAl Viro if (error) 21099f1fafeeSAl Viro return ERR_PTR(error); 2110fe2d35ffSAl Viro 2111fe2d35ffSAl Viro audit_inode(pathname, dir); 211216c2cd71SAl Viro error = -EISDIR; 21131f36f774SAl Viro /* trailing slashes? */ 211431e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21151f36f774SAl Viro goto exit; 21161f36f774SAl Viro 2117a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2118a1e28038SAl Viro 21196c0d46c4SAl Viro dentry = lookup_hash(nd); 21206c0d46c4SAl Viro error = PTR_ERR(dentry); 21216c0d46c4SAl Viro if (IS_ERR(dentry)) { 2122fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2123fb1cc555SAl Viro goto exit; 2124fb1cc555SAl Viro } 2125fb1cc555SAl Viro 21266c0d46c4SAl Viro path->dentry = dentry; 21276c0d46c4SAl Viro path->mnt = nd->path.mnt; 21286c0d46c4SAl Viro 2129fb1cc555SAl Viro /* Negative dentry, just create the file */ 21306c0d46c4SAl Viro if (!dentry->d_inode) { 21316c0d46c4SAl Viro int mode = op->mode; 21326c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21336c0d46c4SAl Viro mode &= ~current_umask(); 2134fb1cc555SAl Viro /* 2135fb1cc555SAl Viro * This write is needed to ensure that a 21366c0d46c4SAl Viro * rw->ro transition does not occur between 2137fb1cc555SAl Viro * the time when the file is created and when 2138fb1cc555SAl Viro * a permanent write count is taken through 2139fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2140fb1cc555SAl Viro */ 2141fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2142fb1cc555SAl Viro if (error) 2143fb1cc555SAl Viro goto exit_mutex_unlock; 2144ca344a89SAl Viro want_write = 1; 21459b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2146ca344a89SAl Viro open_flag &= ~O_TRUNC; 21476c0d46c4SAl Viro will_truncate = 0; 2148bcda7652SAl Viro acc_mode = MAY_OPEN; 21496c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 21506c0d46c4SAl Viro if (error) 21516c0d46c4SAl Viro goto exit_mutex_unlock; 21526c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 21536c0d46c4SAl Viro if (error) 21546c0d46c4SAl Viro goto exit_mutex_unlock; 21556c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 21566c0d46c4SAl Viro dput(nd->path.dentry); 21576c0d46c4SAl Viro nd->path.dentry = dentry; 2158ca344a89SAl Viro goto common; 2159fb1cc555SAl Viro } 2160fb1cc555SAl Viro 2161fb1cc555SAl Viro /* 2162fb1cc555SAl Viro * It already exists. 2163fb1cc555SAl Viro */ 2164fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2165fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2166fb1cc555SAl Viro 2167fb1cc555SAl Viro error = -EEXIST; 2168ca344a89SAl Viro if (open_flag & O_EXCL) 2169fb1cc555SAl Viro goto exit_dput; 2170fb1cc555SAl Viro 21719875cf80SDavid Howells error = follow_managed(path, nd->flags); 21729875cf80SDavid Howells if (error < 0) 2173fb1cc555SAl Viro goto exit_dput; 2174fb1cc555SAl Viro 2175fb1cc555SAl Viro error = -ENOENT; 2176fb1cc555SAl Viro if (!path->dentry->d_inode) 2177fb1cc555SAl Viro goto exit_dput; 21789e67f361SAl Viro 21799e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2180fb1cc555SAl Viro return NULL; 2181fb1cc555SAl Viro 2182fb1cc555SAl Viro path_to_nameidata(path, nd); 218331e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2184fb1cc555SAl Viro error = -EISDIR; 218531e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2186fb1cc555SAl Viro goto exit; 218767ee3ad2SAl Viro ok: 21886c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 21896c0d46c4SAl Viro will_truncate = 0; 21906c0d46c4SAl Viro 21910f9d1a10SAl Viro if (will_truncate) { 21920f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 21930f9d1a10SAl Viro if (error) 21940f9d1a10SAl Viro goto exit; 2195ca344a89SAl Viro want_write = 1; 21960f9d1a10SAl Viro } 2197ca344a89SAl Viro common: 2198bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2199ca344a89SAl Viro if (error) 22000f9d1a10SAl Viro goto exit; 22010f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22020f9d1a10SAl Viro if (!IS_ERR(filp)) { 22030f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22040f9d1a10SAl Viro if (error) { 22050f9d1a10SAl Viro fput(filp); 22060f9d1a10SAl Viro filp = ERR_PTR(error); 22070f9d1a10SAl Viro } 22080f9d1a10SAl Viro } 22090f9d1a10SAl Viro if (!IS_ERR(filp)) { 22100f9d1a10SAl Viro if (will_truncate) { 22110f9d1a10SAl Viro error = handle_truncate(filp); 22120f9d1a10SAl Viro if (error) { 22130f9d1a10SAl Viro fput(filp); 22140f9d1a10SAl Viro filp = ERR_PTR(error); 22150f9d1a10SAl Viro } 22160f9d1a10SAl Viro } 22170f9d1a10SAl Viro } 2218ca344a89SAl Viro out: 2219ca344a89SAl Viro if (want_write) 22200f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22210f9d1a10SAl Viro path_put(&nd->path); 2222fb1cc555SAl Viro return filp; 2223fb1cc555SAl Viro 2224fb1cc555SAl Viro exit_mutex_unlock: 2225fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2226fb1cc555SAl Viro exit_dput: 2227fb1cc555SAl Viro path_put_conditional(path, nd); 2228fb1cc555SAl Viro exit: 2229ca344a89SAl Viro filp = ERR_PTR(error); 2230ca344a89SAl Viro goto out; 2231fb1cc555SAl Viro } 2232fb1cc555SAl Viro 223313aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 223473d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22351da177e4SLinus Torvalds { 2236fe2d35ffSAl Viro struct file *base = NULL; 22374a3fd211SDave Hansen struct file *filp; 22389850c056SAl Viro struct path path; 223913aab428SAl Viro int error; 224031e6b01fSNick Piggin 224131e6b01fSNick Piggin filp = get_empty_filp(); 224231e6b01fSNick Piggin if (!filp) 224331e6b01fSNick Piggin return ERR_PTR(-ENFILE); 224431e6b01fSNick Piggin 224547c805dcSAl Viro filp->f_flags = op->open_flag; 224673d049a4SAl Viro nd->intent.open.file = filp; 224773d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 224873d049a4SAl Viro nd->intent.open.create_mode = op->mode; 224931e6b01fSNick Piggin 225073d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 225131e6b01fSNick Piggin if (unlikely(error)) 225213aab428SAl Viro goto out_filp; 225331e6b01fSNick Piggin 2254fe2d35ffSAl Viro current->total_link_count = 0; 225573d049a4SAl Viro error = link_path_walk(pathname, nd); 225631e6b01fSNick Piggin if (unlikely(error)) 225731e6b01fSNick Piggin goto out_filp; 22581da177e4SLinus Torvalds 225973d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2260806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 22617b9337aaSNick Piggin struct path link = path; 2262def4af30SAl Viro void *cookie; 2263574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 226473d049a4SAl Viro path_put_conditional(&path, nd); 226573d049a4SAl Viro path_put(&nd->path); 226640b39136SAl Viro filp = ERR_PTR(-ELOOP); 226740b39136SAl Viro break; 226840b39136SAl Viro } 226973d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 227073d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2271574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2272c3e380b0SAl Viro if (unlikely(error)) 2273f1afe9efSAl Viro filp = ERR_PTR(error); 2274c3e380b0SAl Viro else 227573d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2276574197e0SAl Viro put_link(nd, &link, cookie); 2277806b681cSAl Viro } 227810fa8e62SAl Viro out: 227973d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 228073d049a4SAl Viro path_put(&nd->root); 2281fe2d35ffSAl Viro if (base) 2282fe2d35ffSAl Viro fput(base); 228373d049a4SAl Viro release_open_intent(nd); 228410fa8e62SAl Viro return filp; 22851da177e4SLinus Torvalds 228631e6b01fSNick Piggin out_filp: 228710fa8e62SAl Viro filp = ERR_PTR(error); 228810fa8e62SAl Viro goto out; 2289de459215SKirill Korotaev } 22901da177e4SLinus Torvalds 229113aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 229213aab428SAl Viro const struct open_flags *op, int flags) 229313aab428SAl Viro { 229473d049a4SAl Viro struct nameidata nd; 229513aab428SAl Viro struct file *filp; 229613aab428SAl Viro 229773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 229813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 229973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 230013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 230173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 230213aab428SAl Viro return filp; 230313aab428SAl Viro } 230413aab428SAl Viro 230573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 230673d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 230773d049a4SAl Viro { 230873d049a4SAl Viro struct nameidata nd; 230973d049a4SAl Viro struct file *file; 231073d049a4SAl Viro 231173d049a4SAl Viro nd.root.mnt = mnt; 231273d049a4SAl Viro nd.root.dentry = dentry; 231373d049a4SAl Viro 231473d049a4SAl Viro flags |= LOOKUP_ROOT; 231573d049a4SAl Viro 2316bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 231773d049a4SAl Viro return ERR_PTR(-ELOOP); 231873d049a4SAl Viro 231973d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 232073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 232173d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 232273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 232373d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 232473d049a4SAl Viro return file; 232573d049a4SAl Viro } 232673d049a4SAl Viro 23271da177e4SLinus Torvalds /** 23281da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23291da177e4SLinus Torvalds * @nd: nameidata info 23301da177e4SLinus Torvalds * @is_dir: directory flag 23311da177e4SLinus Torvalds * 23321da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23331da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2334c663e5d8SChristoph Hellwig * 23354ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23361da177e4SLinus Torvalds */ 23371da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23381da177e4SLinus Torvalds { 2339c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23401da177e4SLinus Torvalds 23414ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2342c663e5d8SChristoph Hellwig /* 2343c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2344c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2345c663e5d8SChristoph Hellwig */ 23461da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23471da177e4SLinus Torvalds goto fail; 23481da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 23493516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2350a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2351c663e5d8SChristoph Hellwig 2352c663e5d8SChristoph Hellwig /* 2353c663e5d8SChristoph Hellwig * Do the final lookup. 2354c663e5d8SChristoph Hellwig */ 235549705b77SChristoph Hellwig dentry = lookup_hash(nd); 23561da177e4SLinus Torvalds if (IS_ERR(dentry)) 23571da177e4SLinus Torvalds goto fail; 2358c663e5d8SChristoph Hellwig 2359e9baf6e5SAl Viro if (dentry->d_inode) 2360e9baf6e5SAl Viro goto eexist; 2361c663e5d8SChristoph Hellwig /* 2362c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2363c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2364c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2365c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2366c663e5d8SChristoph Hellwig */ 2367e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 23681da177e4SLinus Torvalds dput(dentry); 23691da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2370e9baf6e5SAl Viro } 2371e9baf6e5SAl Viro return dentry; 2372e9baf6e5SAl Viro eexist: 2373e9baf6e5SAl Viro dput(dentry); 2374e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 23751da177e4SLinus Torvalds fail: 23761da177e4SLinus Torvalds return dentry; 23771da177e4SLinus Torvalds } 2378f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 23791da177e4SLinus Torvalds 23801da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 23811da177e4SLinus Torvalds { 2382a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23831da177e4SLinus Torvalds 23841da177e4SLinus Torvalds if (error) 23851da177e4SLinus Torvalds return error; 23861da177e4SLinus Torvalds 2387e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2388e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 23891da177e4SLinus Torvalds return -EPERM; 23901da177e4SLinus Torvalds 2391acfa4380SAl Viro if (!dir->i_op->mknod) 23921da177e4SLinus Torvalds return -EPERM; 23931da177e4SLinus Torvalds 239408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 239508ce5f16SSerge E. Hallyn if (error) 239608ce5f16SSerge E. Hallyn return error; 239708ce5f16SSerge E. Hallyn 23981da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 23991da177e4SLinus Torvalds if (error) 24001da177e4SLinus Torvalds return error; 24011da177e4SLinus Torvalds 24021da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2403a74574aaSStephen Smalley if (!error) 2404f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24051da177e4SLinus Torvalds return error; 24061da177e4SLinus Torvalds } 24071da177e4SLinus Torvalds 2408463c3197SDave Hansen static int may_mknod(mode_t mode) 2409463c3197SDave Hansen { 2410463c3197SDave Hansen switch (mode & S_IFMT) { 2411463c3197SDave Hansen case S_IFREG: 2412463c3197SDave Hansen case S_IFCHR: 2413463c3197SDave Hansen case S_IFBLK: 2414463c3197SDave Hansen case S_IFIFO: 2415463c3197SDave Hansen case S_IFSOCK: 2416463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2417463c3197SDave Hansen return 0; 2418463c3197SDave Hansen case S_IFDIR: 2419463c3197SDave Hansen return -EPERM; 2420463c3197SDave Hansen default: 2421463c3197SDave Hansen return -EINVAL; 2422463c3197SDave Hansen } 2423463c3197SDave Hansen } 2424463c3197SDave Hansen 24252e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24262e4d0924SHeiko Carstens unsigned, dev) 24271da177e4SLinus Torvalds { 24282ad94ae6SAl Viro int error; 24291da177e4SLinus Torvalds char *tmp; 24301da177e4SLinus Torvalds struct dentry *dentry; 24311da177e4SLinus Torvalds struct nameidata nd; 24321da177e4SLinus Torvalds 24331da177e4SLinus Torvalds if (S_ISDIR(mode)) 24341da177e4SLinus Torvalds return -EPERM; 24351da177e4SLinus Torvalds 24362ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24371da177e4SLinus Torvalds if (error) 24382ad94ae6SAl Viro return error; 24392ad94ae6SAl Viro 24401da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2441463c3197SDave Hansen if (IS_ERR(dentry)) { 24421da177e4SLinus Torvalds error = PTR_ERR(dentry); 2443463c3197SDave Hansen goto out_unlock; 2444463c3197SDave Hansen } 24454ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2446ce3b0f8dSAl Viro mode &= ~current_umask(); 2447463c3197SDave Hansen error = may_mknod(mode); 2448463c3197SDave Hansen if (error) 2449463c3197SDave Hansen goto out_dput; 2450463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2451463c3197SDave Hansen if (error) 2452463c3197SDave Hansen goto out_dput; 2453be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2454be6d3e56SKentaro Takeda if (error) 2455be6d3e56SKentaro Takeda goto out_drop_write; 24561da177e4SLinus Torvalds switch (mode & S_IFMT) { 24571da177e4SLinus Torvalds case 0: case S_IFREG: 24584ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 24591da177e4SLinus Torvalds break; 24601da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 24614ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 24621da177e4SLinus Torvalds new_decode_dev(dev)); 24631da177e4SLinus Torvalds break; 24641da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 24654ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 24661da177e4SLinus Torvalds break; 24671da177e4SLinus Torvalds } 2468be6d3e56SKentaro Takeda out_drop_write: 2469463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2470463c3197SDave Hansen out_dput: 24711da177e4SLinus Torvalds dput(dentry); 2472463c3197SDave Hansen out_unlock: 24734ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24741d957f9bSJan Blunck path_put(&nd.path); 24751da177e4SLinus Torvalds putname(tmp); 24761da177e4SLinus Torvalds 24771da177e4SLinus Torvalds return error; 24781da177e4SLinus Torvalds } 24791da177e4SLinus Torvalds 24803480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 24815590ff0dSUlrich Drepper { 24825590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 24835590ff0dSUlrich Drepper } 24845590ff0dSUlrich Drepper 24851da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 24861da177e4SLinus Torvalds { 2487a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24881da177e4SLinus Torvalds 24891da177e4SLinus Torvalds if (error) 24901da177e4SLinus Torvalds return error; 24911da177e4SLinus Torvalds 2492acfa4380SAl Viro if (!dir->i_op->mkdir) 24931da177e4SLinus Torvalds return -EPERM; 24941da177e4SLinus Torvalds 24951da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 24961da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 24971da177e4SLinus Torvalds if (error) 24981da177e4SLinus Torvalds return error; 24991da177e4SLinus Torvalds 25001da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2501a74574aaSStephen Smalley if (!error) 2502f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25031da177e4SLinus Torvalds return error; 25041da177e4SLinus Torvalds } 25051da177e4SLinus Torvalds 25062e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25071da177e4SLinus Torvalds { 25081da177e4SLinus Torvalds int error = 0; 25091da177e4SLinus Torvalds char * tmp; 25106902d925SDave Hansen struct dentry *dentry; 25116902d925SDave Hansen struct nameidata nd; 25121da177e4SLinus Torvalds 25132ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25142ad94ae6SAl Viro if (error) 25156902d925SDave Hansen goto out_err; 25161da177e4SLinus Torvalds 25171da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25181da177e4SLinus Torvalds error = PTR_ERR(dentry); 25196902d925SDave Hansen if (IS_ERR(dentry)) 25206902d925SDave Hansen goto out_unlock; 25216902d925SDave Hansen 25224ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2523ce3b0f8dSAl Viro mode &= ~current_umask(); 2524463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2525463c3197SDave Hansen if (error) 2526463c3197SDave Hansen goto out_dput; 2527be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2528be6d3e56SKentaro Takeda if (error) 2529be6d3e56SKentaro Takeda goto out_drop_write; 25304ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2531be6d3e56SKentaro Takeda out_drop_write: 2532463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2533463c3197SDave Hansen out_dput: 25341da177e4SLinus Torvalds dput(dentry); 25356902d925SDave Hansen out_unlock: 25364ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25371d957f9bSJan Blunck path_put(&nd.path); 25381da177e4SLinus Torvalds putname(tmp); 25396902d925SDave Hansen out_err: 25401da177e4SLinus Torvalds return error; 25411da177e4SLinus Torvalds } 25421da177e4SLinus Torvalds 25433cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25445590ff0dSUlrich Drepper { 25455590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25465590ff0dSUlrich Drepper } 25475590ff0dSUlrich Drepper 25481da177e4SLinus Torvalds /* 2549a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2550a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2551a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2552a71905f0SSage Weil * then we drop the dentry now. 25531da177e4SLinus Torvalds * 25541da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 25551da177e4SLinus Torvalds * do a 25561da177e4SLinus Torvalds * 25571da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 25581da177e4SLinus Torvalds * return -EBUSY; 25591da177e4SLinus Torvalds * 25601da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 25611da177e4SLinus Torvalds * that is still in use by something else.. 25621da177e4SLinus Torvalds */ 25631da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 25641da177e4SLinus Torvalds { 25651da177e4SLinus Torvalds shrink_dcache_parent(dentry); 25661da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 256764252c75SSage Weil if (dentry->d_count == 1) 25681da177e4SLinus Torvalds __d_drop(dentry); 25691da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 25701da177e4SLinus Torvalds } 25711da177e4SLinus Torvalds 25721da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 25731da177e4SLinus Torvalds { 25741da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 25751da177e4SLinus Torvalds 25761da177e4SLinus Torvalds if (error) 25771da177e4SLinus Torvalds return error; 25781da177e4SLinus Torvalds 2579acfa4380SAl Viro if (!dir->i_op->rmdir) 25801da177e4SLinus Torvalds return -EPERM; 25811da177e4SLinus Torvalds 25821b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2583912dbc15SSage Weil 25841da177e4SLinus Torvalds error = -EBUSY; 2585912dbc15SSage Weil if (d_mountpoint(dentry)) 2586912dbc15SSage Weil goto out; 2587912dbc15SSage Weil 25881da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2589912dbc15SSage Weil if (error) 2590912dbc15SSage Weil goto out; 2591912dbc15SSage Weil 25921da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2593912dbc15SSage Weil if (error) 2594912dbc15SSage Weil goto out; 2595912dbc15SSage Weil 25961da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2597d83c49f3SAl Viro dont_mount(dentry); 25981da177e4SLinus Torvalds 2599912dbc15SSage Weil out: 2600912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 2601912dbc15SSage Weil if (!error) 2602912dbc15SSage Weil d_delete(dentry); 26031da177e4SLinus Torvalds return error; 26041da177e4SLinus Torvalds } 26051da177e4SLinus Torvalds 26065590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26071da177e4SLinus Torvalds { 26081da177e4SLinus Torvalds int error = 0; 26091da177e4SLinus Torvalds char * name; 26101da177e4SLinus Torvalds struct dentry *dentry; 26111da177e4SLinus Torvalds struct nameidata nd; 26121da177e4SLinus Torvalds 26132ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26141da177e4SLinus Torvalds if (error) 26152ad94ae6SAl Viro return error; 26161da177e4SLinus Torvalds 26171da177e4SLinus Torvalds switch(nd.last_type) { 26181da177e4SLinus Torvalds case LAST_DOTDOT: 26191da177e4SLinus Torvalds error = -ENOTEMPTY; 26201da177e4SLinus Torvalds goto exit1; 26211da177e4SLinus Torvalds case LAST_DOT: 26221da177e4SLinus Torvalds error = -EINVAL; 26231da177e4SLinus Torvalds goto exit1; 26241da177e4SLinus Torvalds case LAST_ROOT: 26251da177e4SLinus Torvalds error = -EBUSY; 26261da177e4SLinus Torvalds goto exit1; 26271da177e4SLinus Torvalds } 26280612d9fbSOGAWA Hirofumi 26290612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26300612d9fbSOGAWA Hirofumi 26314ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 263249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26331da177e4SLinus Torvalds error = PTR_ERR(dentry); 26346902d925SDave Hansen if (IS_ERR(dentry)) 26356902d925SDave Hansen goto exit2; 26360622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26370622753bSDave Hansen if (error) 26380622753bSDave Hansen goto exit3; 2639be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2640be6d3e56SKentaro Takeda if (error) 2641be6d3e56SKentaro Takeda goto exit4; 26424ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2643be6d3e56SKentaro Takeda exit4: 26440622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26450622753bSDave Hansen exit3: 26461da177e4SLinus Torvalds dput(dentry); 26476902d925SDave Hansen exit2: 26484ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26491da177e4SLinus Torvalds exit1: 26501d957f9bSJan Blunck path_put(&nd.path); 26511da177e4SLinus Torvalds putname(name); 26521da177e4SLinus Torvalds return error; 26531da177e4SLinus Torvalds } 26541da177e4SLinus Torvalds 26553cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 26565590ff0dSUlrich Drepper { 26575590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 26585590ff0dSUlrich Drepper } 26595590ff0dSUlrich Drepper 26601da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 26611da177e4SLinus Torvalds { 26621da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 26631da177e4SLinus Torvalds 26641da177e4SLinus Torvalds if (error) 26651da177e4SLinus Torvalds return error; 26661da177e4SLinus Torvalds 2667acfa4380SAl Viro if (!dir->i_op->unlink) 26681da177e4SLinus Torvalds return -EPERM; 26691da177e4SLinus Torvalds 26701b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26711da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26721da177e4SLinus Torvalds error = -EBUSY; 26731da177e4SLinus Torvalds else { 26741da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2675bec1052eSAl Viro if (!error) { 26761da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2677bec1052eSAl Viro if (!error) 2678d83c49f3SAl Viro dont_mount(dentry); 2679bec1052eSAl Viro } 26801da177e4SLinus Torvalds } 26811b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 26841da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2685ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 26861da177e4SLinus Torvalds d_delete(dentry); 26871da177e4SLinus Torvalds } 26880eeca283SRobert Love 26891da177e4SLinus Torvalds return error; 26901da177e4SLinus Torvalds } 26911da177e4SLinus Torvalds 26921da177e4SLinus Torvalds /* 26931da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 26941b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 26951da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 26961da177e4SLinus Torvalds * while waiting on the I/O. 26971da177e4SLinus Torvalds */ 26985590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 26991da177e4SLinus Torvalds { 27002ad94ae6SAl Viro int error; 27011da177e4SLinus Torvalds char *name; 27021da177e4SLinus Torvalds struct dentry *dentry; 27031da177e4SLinus Torvalds struct nameidata nd; 27041da177e4SLinus Torvalds struct inode *inode = NULL; 27051da177e4SLinus Torvalds 27062ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27071da177e4SLinus Torvalds if (error) 27082ad94ae6SAl Viro return error; 27092ad94ae6SAl Viro 27101da177e4SLinus Torvalds error = -EISDIR; 27111da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27121da177e4SLinus Torvalds goto exit1; 27130612d9fbSOGAWA Hirofumi 27140612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27150612d9fbSOGAWA Hirofumi 27164ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 271749705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27181da177e4SLinus Torvalds error = PTR_ERR(dentry); 27191da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27201da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 27211da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 27221da177e4SLinus Torvalds goto slashes; 27231da177e4SLinus Torvalds inode = dentry->d_inode; 27241da177e4SLinus Torvalds if (inode) 27257de9c6eeSAl Viro ihold(inode); 27260622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27270622753bSDave Hansen if (error) 27280622753bSDave Hansen goto exit2; 2729be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2730be6d3e56SKentaro Takeda if (error) 2731be6d3e56SKentaro Takeda goto exit3; 27324ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2733be6d3e56SKentaro Takeda exit3: 27340622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27351da177e4SLinus Torvalds exit2: 27361da177e4SLinus Torvalds dput(dentry); 27371da177e4SLinus Torvalds } 27384ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27391da177e4SLinus Torvalds if (inode) 27401da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27411da177e4SLinus Torvalds exit1: 27421d957f9bSJan Blunck path_put(&nd.path); 27431da177e4SLinus Torvalds putname(name); 27441da177e4SLinus Torvalds return error; 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds slashes: 27471da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27481da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 27491da177e4SLinus Torvalds goto exit2; 27501da177e4SLinus Torvalds } 27511da177e4SLinus Torvalds 27522e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 27535590ff0dSUlrich Drepper { 27545590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 27555590ff0dSUlrich Drepper return -EINVAL; 27565590ff0dSUlrich Drepper 27575590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 27585590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 27595590ff0dSUlrich Drepper 27605590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 27615590ff0dSUlrich Drepper } 27625590ff0dSUlrich Drepper 27633480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 27645590ff0dSUlrich Drepper { 27655590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 27665590ff0dSUlrich Drepper } 27675590ff0dSUlrich Drepper 2768db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 27691da177e4SLinus Torvalds { 2770a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27711da177e4SLinus Torvalds 27721da177e4SLinus Torvalds if (error) 27731da177e4SLinus Torvalds return error; 27741da177e4SLinus Torvalds 2775acfa4380SAl Viro if (!dir->i_op->symlink) 27761da177e4SLinus Torvalds return -EPERM; 27771da177e4SLinus Torvalds 27781da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 27791da177e4SLinus Torvalds if (error) 27801da177e4SLinus Torvalds return error; 27811da177e4SLinus Torvalds 27821da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2783a74574aaSStephen Smalley if (!error) 2784f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27851da177e4SLinus Torvalds return error; 27861da177e4SLinus Torvalds } 27871da177e4SLinus Torvalds 27882e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 27892e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 27901da177e4SLinus Torvalds { 27912ad94ae6SAl Viro int error; 27921da177e4SLinus Torvalds char *from; 27931da177e4SLinus Torvalds char *to; 27946902d925SDave Hansen struct dentry *dentry; 27956902d925SDave Hansen struct nameidata nd; 27961da177e4SLinus Torvalds 27971da177e4SLinus Torvalds from = getname(oldname); 27981da177e4SLinus Torvalds if (IS_ERR(from)) 27991da177e4SLinus Torvalds return PTR_ERR(from); 28002ad94ae6SAl Viro 28012ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28022ad94ae6SAl Viro if (error) 28036902d925SDave Hansen goto out_putname; 28041da177e4SLinus Torvalds 28051da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28061da177e4SLinus Torvalds error = PTR_ERR(dentry); 28076902d925SDave Hansen if (IS_ERR(dentry)) 28086902d925SDave Hansen goto out_unlock; 28096902d925SDave Hansen 281075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 281175c3f29dSDave Hansen if (error) 281275c3f29dSDave Hansen goto out_dput; 2813be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2814be6d3e56SKentaro Takeda if (error) 2815be6d3e56SKentaro Takeda goto out_drop_write; 2816db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2817be6d3e56SKentaro Takeda out_drop_write: 281875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 281975c3f29dSDave Hansen out_dput: 28201da177e4SLinus Torvalds dput(dentry); 28216902d925SDave Hansen out_unlock: 28224ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28231d957f9bSJan Blunck path_put(&nd.path); 28241da177e4SLinus Torvalds putname(to); 28256902d925SDave Hansen out_putname: 28261da177e4SLinus Torvalds putname(from); 28271da177e4SLinus Torvalds return error; 28281da177e4SLinus Torvalds } 28291da177e4SLinus Torvalds 28303480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28315590ff0dSUlrich Drepper { 28325590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28335590ff0dSUlrich Drepper } 28345590ff0dSUlrich Drepper 28351da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28361da177e4SLinus Torvalds { 28371da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28381da177e4SLinus Torvalds int error; 28391da177e4SLinus Torvalds 28401da177e4SLinus Torvalds if (!inode) 28411da177e4SLinus Torvalds return -ENOENT; 28421da177e4SLinus Torvalds 2843a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28441da177e4SLinus Torvalds if (error) 28451da177e4SLinus Torvalds return error; 28461da177e4SLinus Torvalds 28471da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28481da177e4SLinus Torvalds return -EXDEV; 28491da177e4SLinus Torvalds 28501da177e4SLinus Torvalds /* 28511da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 28521da177e4SLinus Torvalds */ 28531da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 28541da177e4SLinus Torvalds return -EPERM; 2855acfa4380SAl Viro if (!dir->i_op->link) 28561da177e4SLinus Torvalds return -EPERM; 28577e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 28581da177e4SLinus Torvalds return -EPERM; 28591da177e4SLinus Torvalds 28601da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 28611da177e4SLinus Torvalds if (error) 28621da177e4SLinus Torvalds return error; 28631da177e4SLinus Torvalds 28647e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2865aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2866aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2867aae8a97dSAneesh Kumar K.V error = -ENOENT; 2868aae8a97dSAneesh Kumar K.V else 28691da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 28707e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2871e31e14ecSStephen Smalley if (!error) 28727e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 28731da177e4SLinus Torvalds return error; 28741da177e4SLinus Torvalds } 28751da177e4SLinus Torvalds 28761da177e4SLinus Torvalds /* 28771da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 28781da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 28791da177e4SLinus Torvalds * newname. --KAB 28801da177e4SLinus Torvalds * 28811da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 28821da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 28831da177e4SLinus Torvalds * and other special files. --ADM 28841da177e4SLinus Torvalds */ 28852e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 28862e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 28871da177e4SLinus Torvalds { 28881da177e4SLinus Torvalds struct dentry *new_dentry; 28892d8f3038SAl Viro struct nameidata nd; 28902d8f3038SAl Viro struct path old_path; 289111a7b371SAneesh Kumar K.V int how = 0; 28921da177e4SLinus Torvalds int error; 28931da177e4SLinus Torvalds char *to; 28941da177e4SLinus Torvalds 289511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2896c04030e1SUlrich Drepper return -EINVAL; 289711a7b371SAneesh Kumar K.V /* 289811a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 289911a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 290011a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 290111a7b371SAneesh Kumar K.V */ 290211a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 290311a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 290411a7b371SAneesh Kumar K.V return -ENOENT; 290511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 290611a7b371SAneesh Kumar K.V } 2907c04030e1SUlrich Drepper 290811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 290911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 291011a7b371SAneesh Kumar K.V 291111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29121da177e4SLinus Torvalds if (error) 29132ad94ae6SAl Viro return error; 29142ad94ae6SAl Viro 29152ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29161da177e4SLinus Torvalds if (error) 29171da177e4SLinus Torvalds goto out; 29181da177e4SLinus Torvalds error = -EXDEV; 29192d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29201da177e4SLinus Torvalds goto out_release; 29211da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29221da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29236902d925SDave Hansen if (IS_ERR(new_dentry)) 29246902d925SDave Hansen goto out_unlock; 292575c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 292675c3f29dSDave Hansen if (error) 292775c3f29dSDave Hansen goto out_dput; 2928be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2929be6d3e56SKentaro Takeda if (error) 2930be6d3e56SKentaro Takeda goto out_drop_write; 29312d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2932be6d3e56SKentaro Takeda out_drop_write: 293375c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 293475c3f29dSDave Hansen out_dput: 29351da177e4SLinus Torvalds dput(new_dentry); 29366902d925SDave Hansen out_unlock: 29374ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29381da177e4SLinus Torvalds out_release: 29391d957f9bSJan Blunck path_put(&nd.path); 29402ad94ae6SAl Viro putname(to); 29411da177e4SLinus Torvalds out: 29422d8f3038SAl Viro path_put(&old_path); 29431da177e4SLinus Torvalds 29441da177e4SLinus Torvalds return error; 29451da177e4SLinus Torvalds } 29461da177e4SLinus Torvalds 29473480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29485590ff0dSUlrich Drepper { 2949c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29505590ff0dSUlrich Drepper } 29515590ff0dSUlrich Drepper 29521da177e4SLinus Torvalds /* 29531da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29541da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29551da177e4SLinus Torvalds * Problems: 29561da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29571da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29581da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2959a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29601da177e4SLinus Torvalds * story. 29611da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29621b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29631da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29641da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2965a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 29661da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 29671da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 29681da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2969a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 29701da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 29711da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 29721da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 2973e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 29741b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 29751da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 2976c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 29771da177e4SLinus Torvalds * locking]. 29781da177e4SLinus Torvalds */ 297975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 29801da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 29811da177e4SLinus Torvalds { 29821da177e4SLinus Torvalds int error = 0; 29839055cba7SSage Weil struct inode *target = new_dentry->d_inode; 29841da177e4SLinus Torvalds 29851da177e4SLinus Torvalds /* 29861da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 29871da177e4SLinus Torvalds * we'll need to flip '..'. 29881da177e4SLinus Torvalds */ 29891da177e4SLinus Torvalds if (new_dir != old_dir) { 2990f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 29911da177e4SLinus Torvalds if (error) 29921da177e4SLinus Torvalds return error; 29931da177e4SLinus Torvalds } 29941da177e4SLinus Torvalds 29951da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 29961da177e4SLinus Torvalds if (error) 29971da177e4SLinus Torvalds return error; 29981da177e4SLinus Torvalds 2999d83c49f3SAl Viro if (target) 30001b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30019055cba7SSage Weil 30021da177e4SLinus Torvalds error = -EBUSY; 30039055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 30049055cba7SSage Weil goto out; 30059055cba7SSage Weil 30061da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30079055cba7SSage Weil if (error) 30089055cba7SSage Weil goto out; 30099055cba7SSage Weil 30101da177e4SLinus Torvalds if (target) { 30111da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3012d83c49f3SAl Viro dont_mount(new_dentry); 3013d83c49f3SAl Viro } 30149055cba7SSage Weil out: 30159055cba7SSage Weil if (target) 30161b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 3017e31e14ecSStephen Smalley if (!error) 3018349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30191da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30201da177e4SLinus Torvalds return error; 30211da177e4SLinus Torvalds } 30221da177e4SLinus Torvalds 302375c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30241da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30251da177e4SLinus Torvalds { 302651892bbbSSage Weil struct inode *target = new_dentry->d_inode; 30271da177e4SLinus Torvalds int error; 30281da177e4SLinus Torvalds 30291da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30301da177e4SLinus Torvalds if (error) 30311da177e4SLinus Torvalds return error; 30321da177e4SLinus Torvalds 30331da177e4SLinus Torvalds dget(new_dentry); 30341da177e4SLinus Torvalds if (target) 30351b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 303651892bbbSSage Weil 30371da177e4SLinus Torvalds error = -EBUSY; 303851892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 303951892bbbSSage Weil goto out; 304051892bbbSSage Weil 30411da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 304251892bbbSSage Weil if (error) 304351892bbbSSage Weil goto out; 304451892bbbSSage Weil 3045bec1052eSAl Viro if (target) 3046d83c49f3SAl Viro dont_mount(new_dentry); 3047349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30481da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 304951892bbbSSage Weil out: 30501da177e4SLinus Torvalds if (target) 30511b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30521da177e4SLinus Torvalds dput(new_dentry); 30531da177e4SLinus Torvalds return error; 30541da177e4SLinus Torvalds } 30551da177e4SLinus Torvalds 30561da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30571da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30581da177e4SLinus Torvalds { 30591da177e4SLinus Torvalds int error; 30601da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 306159b0df21SEric Paris const unsigned char *old_name; 30621da177e4SLinus Torvalds 30631da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 30641da177e4SLinus Torvalds return 0; 30651da177e4SLinus Torvalds 30661da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 30671da177e4SLinus Torvalds if (error) 30681da177e4SLinus Torvalds return error; 30691da177e4SLinus Torvalds 30701da177e4SLinus Torvalds if (!new_dentry->d_inode) 3071a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 30721da177e4SLinus Torvalds else 30731da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 30741da177e4SLinus Torvalds if (error) 30751da177e4SLinus Torvalds return error; 30761da177e4SLinus Torvalds 3077acfa4380SAl Viro if (!old_dir->i_op->rename) 30781da177e4SLinus Torvalds return -EPERM; 30791da177e4SLinus Torvalds 30800eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 30810eeca283SRobert Love 30821da177e4SLinus Torvalds if (is_dir) 30831da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 30841da177e4SLinus Torvalds else 30851da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3086123df294SAl Viro if (!error) 3087123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 30885a190ae6SAl Viro new_dentry->d_inode, old_dentry); 30890eeca283SRobert Love fsnotify_oldname_free(old_name); 30900eeca283SRobert Love 30911da177e4SLinus Torvalds return error; 30921da177e4SLinus Torvalds } 30931da177e4SLinus Torvalds 30942e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 30952e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 30961da177e4SLinus Torvalds { 30971da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 30981da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 30991da177e4SLinus Torvalds struct dentry *trap; 31001da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31012ad94ae6SAl Viro char *from; 31022ad94ae6SAl Viro char *to; 31032ad94ae6SAl Viro int error; 31041da177e4SLinus Torvalds 31052ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31061da177e4SLinus Torvalds if (error) 31071da177e4SLinus Torvalds goto exit; 31081da177e4SLinus Torvalds 31092ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31101da177e4SLinus Torvalds if (error) 31111da177e4SLinus Torvalds goto exit1; 31121da177e4SLinus Torvalds 31131da177e4SLinus Torvalds error = -EXDEV; 31144ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31151da177e4SLinus Torvalds goto exit2; 31161da177e4SLinus Torvalds 31174ac91378SJan Blunck old_dir = oldnd.path.dentry; 31181da177e4SLinus Torvalds error = -EBUSY; 31191da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31201da177e4SLinus Torvalds goto exit2; 31211da177e4SLinus Torvalds 31224ac91378SJan Blunck new_dir = newnd.path.dentry; 31231da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31241da177e4SLinus Torvalds goto exit2; 31251da177e4SLinus Torvalds 31260612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31270612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31284e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31290612d9fbSOGAWA Hirofumi 31301da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31311da177e4SLinus Torvalds 313249705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31331da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31341da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31351da177e4SLinus Torvalds goto exit3; 31361da177e4SLinus Torvalds /* source must exist */ 31371da177e4SLinus Torvalds error = -ENOENT; 31381da177e4SLinus Torvalds if (!old_dentry->d_inode) 31391da177e4SLinus Torvalds goto exit4; 31401da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31411da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31421da177e4SLinus Torvalds error = -ENOTDIR; 31431da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31441da177e4SLinus Torvalds goto exit4; 31451da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31461da177e4SLinus Torvalds goto exit4; 31471da177e4SLinus Torvalds } 31481da177e4SLinus Torvalds /* source should not be ancestor of target */ 31491da177e4SLinus Torvalds error = -EINVAL; 31501da177e4SLinus Torvalds if (old_dentry == trap) 31511da177e4SLinus Torvalds goto exit4; 315249705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31531da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31541da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31551da177e4SLinus Torvalds goto exit4; 31561da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31571da177e4SLinus Torvalds error = -ENOTEMPTY; 31581da177e4SLinus Torvalds if (new_dentry == trap) 31591da177e4SLinus Torvalds goto exit5; 31601da177e4SLinus Torvalds 31619079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 31629079b1ebSDave Hansen if (error) 31639079b1ebSDave Hansen goto exit5; 3164be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3165be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3166be6d3e56SKentaro Takeda if (error) 3167be6d3e56SKentaro Takeda goto exit6; 31681da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 31691da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3170be6d3e56SKentaro Takeda exit6: 31719079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 31721da177e4SLinus Torvalds exit5: 31731da177e4SLinus Torvalds dput(new_dentry); 31741da177e4SLinus Torvalds exit4: 31751da177e4SLinus Torvalds dput(old_dentry); 31761da177e4SLinus Torvalds exit3: 31771da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 31781da177e4SLinus Torvalds exit2: 31791d957f9bSJan Blunck path_put(&newnd.path); 31802ad94ae6SAl Viro putname(to); 31811da177e4SLinus Torvalds exit1: 31821d957f9bSJan Blunck path_put(&oldnd.path); 31831da177e4SLinus Torvalds putname(from); 31842ad94ae6SAl Viro exit: 31851da177e4SLinus Torvalds return error; 31861da177e4SLinus Torvalds } 31871da177e4SLinus Torvalds 3188a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 31895590ff0dSUlrich Drepper { 31905590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 31915590ff0dSUlrich Drepper } 31925590ff0dSUlrich Drepper 31931da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 31941da177e4SLinus Torvalds { 31951da177e4SLinus Torvalds int len; 31961da177e4SLinus Torvalds 31971da177e4SLinus Torvalds len = PTR_ERR(link); 31981da177e4SLinus Torvalds if (IS_ERR(link)) 31991da177e4SLinus Torvalds goto out; 32001da177e4SLinus Torvalds 32011da177e4SLinus Torvalds len = strlen(link); 32021da177e4SLinus Torvalds if (len > (unsigned) buflen) 32031da177e4SLinus Torvalds len = buflen; 32041da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32051da177e4SLinus Torvalds len = -EFAULT; 32061da177e4SLinus Torvalds out: 32071da177e4SLinus Torvalds return len; 32081da177e4SLinus Torvalds } 32091da177e4SLinus Torvalds 32101da177e4SLinus Torvalds /* 32111da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32121da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32131da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32141da177e4SLinus Torvalds */ 32151da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32161da177e4SLinus Torvalds { 32171da177e4SLinus Torvalds struct nameidata nd; 3218cc314eefSLinus Torvalds void *cookie; 3219694a1764SMarcin Slusarz int res; 3220cc314eefSLinus Torvalds 32211da177e4SLinus Torvalds nd.depth = 0; 3222cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3223694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3224694a1764SMarcin Slusarz return PTR_ERR(cookie); 3225694a1764SMarcin Slusarz 3226694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32271da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3228cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3229694a1764SMarcin Slusarz return res; 32301da177e4SLinus Torvalds } 32311da177e4SLinus Torvalds 32321da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32331da177e4SLinus Torvalds { 32341da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32351da177e4SLinus Torvalds } 32361da177e4SLinus Torvalds 32371da177e4SLinus Torvalds /* get the link contents into pagecache */ 32381da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32391da177e4SLinus Torvalds { 3240ebd09abbSDuane Griffin char *kaddr; 32411da177e4SLinus Torvalds struct page *page; 32421da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3243090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32441da177e4SLinus Torvalds if (IS_ERR(page)) 32456fe6900eSNick Piggin return (char*)page; 32461da177e4SLinus Torvalds *ppage = page; 3247ebd09abbSDuane Griffin kaddr = kmap(page); 3248ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3249ebd09abbSDuane Griffin return kaddr; 32501da177e4SLinus Torvalds } 32511da177e4SLinus Torvalds 32521da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32531da177e4SLinus Torvalds { 32541da177e4SLinus Torvalds struct page *page = NULL; 32551da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32561da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32571da177e4SLinus Torvalds if (page) { 32581da177e4SLinus Torvalds kunmap(page); 32591da177e4SLinus Torvalds page_cache_release(page); 32601da177e4SLinus Torvalds } 32611da177e4SLinus Torvalds return res; 32621da177e4SLinus Torvalds } 32631da177e4SLinus Torvalds 3264cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 32651da177e4SLinus Torvalds { 3266cc314eefSLinus Torvalds struct page *page = NULL; 32671da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3268cc314eefSLinus Torvalds return page; 32691da177e4SLinus Torvalds } 32701da177e4SLinus Torvalds 3271cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 32721da177e4SLinus Torvalds { 3273cc314eefSLinus Torvalds struct page *page = cookie; 3274cc314eefSLinus Torvalds 3275cc314eefSLinus Torvalds if (page) { 32761da177e4SLinus Torvalds kunmap(page); 32771da177e4SLinus Torvalds page_cache_release(page); 32781da177e4SLinus Torvalds } 32791da177e4SLinus Torvalds } 32801da177e4SLinus Torvalds 328154566b2cSNick Piggin /* 328254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 328354566b2cSNick Piggin */ 328454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 32851da177e4SLinus Torvalds { 32861da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 32870adb25d2SKirill Korotaev struct page *page; 3288afddba49SNick Piggin void *fsdata; 3289beb497abSDmitriy Monakhov int err; 32901da177e4SLinus Torvalds char *kaddr; 329154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 329254566b2cSNick Piggin if (nofs) 329354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 32941da177e4SLinus Torvalds 32957e53cac4SNeilBrown retry: 3296afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 329754566b2cSNick Piggin flags, &page, &fsdata); 32981da177e4SLinus Torvalds if (err) 3299afddba49SNick Piggin goto fail; 3300afddba49SNick Piggin 33011da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33021da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33031da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3304afddba49SNick Piggin 3305afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3306afddba49SNick Piggin page, fsdata); 33071da177e4SLinus Torvalds if (err < 0) 33081da177e4SLinus Torvalds goto fail; 3309afddba49SNick Piggin if (err < len-1) 3310afddba49SNick Piggin goto retry; 3311afddba49SNick Piggin 33121da177e4SLinus Torvalds mark_inode_dirty(inode); 33131da177e4SLinus Torvalds return 0; 33141da177e4SLinus Torvalds fail: 33151da177e4SLinus Torvalds return err; 33161da177e4SLinus Torvalds } 33171da177e4SLinus Torvalds 33180adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33190adb25d2SKirill Korotaev { 33200adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 332154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33220adb25d2SKirill Korotaev } 33230adb25d2SKirill Korotaev 332492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33251da177e4SLinus Torvalds .readlink = generic_readlink, 33261da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33271da177e4SLinus Torvalds .put_link = page_put_link, 33281da177e4SLinus Torvalds }; 33291da177e4SLinus Torvalds 33302d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3331cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33321da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33331da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33341da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33351da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33361da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33371da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33381da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33391da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33401da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33410adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33421da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33431da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3344c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3345d1811465SAl Viro EXPORT_SYMBOL(kern_path); 334616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3347f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33488c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 33491da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33501da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33511da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33521da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33531da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33541da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33551da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33561da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33571da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33581da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33591da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33601da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33611da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 33621da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3363