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 731da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1111da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1121da177e4SLinus Torvalds * kernel data space before using them.. 1131da177e4SLinus Torvalds * 1141da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1151da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1161da177e4SLinus Torvalds */ 117858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1181da177e4SLinus Torvalds { 1191da177e4SLinus Torvalds int retval; 1201da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1231da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1241da177e4SLinus Torvalds return -EFAULT; 1251da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1261da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1301da177e4SLinus Torvalds if (retval > 0) { 1311da177e4SLinus Torvalds if (retval < len) 1321da177e4SLinus Torvalds return 0; 1331da177e4SLinus Torvalds return -ENAMETOOLONG; 1341da177e4SLinus Torvalds } else if (!retval) 1351da177e4SLinus Torvalds retval = -ENOENT; 1361da177e4SLinus Torvalds return retval; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 139f52e0c11SAl Viro static char *getname_flags(const char __user * filename, int flags) 1401da177e4SLinus Torvalds { 1411da177e4SLinus Torvalds char *tmp, *result; 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1441da177e4SLinus Torvalds tmp = __getname(); 1451da177e4SLinus Torvalds if (tmp) { 1461da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds result = tmp; 1491da177e4SLinus Torvalds if (retval < 0) { 150f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 155f52e0c11SAl Viro } 1561da177e4SLinus Torvalds audit_getname(result); 1571da177e4SLinus Torvalds return result; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 160f52e0c11SAl Viro char *getname(const char __user * filename) 161f52e0c11SAl Viro { 162f52e0c11SAl Viro return getname_flags(filename, 0); 163f52e0c11SAl Viro } 164f52e0c11SAl Viro 1651da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1661da177e4SLinus Torvalds void putname(const char *name) 1671da177e4SLinus Torvalds { 1685ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1691da177e4SLinus Torvalds audit_putname(name); 1701da177e4SLinus Torvalds else 1711da177e4SLinus Torvalds __putname(name); 1721da177e4SLinus Torvalds } 1731da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1741da177e4SLinus Torvalds #endif 1751da177e4SLinus Torvalds 1765909ccaaSLinus Torvalds /* 1775909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1785909ccaaSLinus Torvalds */ 179b74c79e9SNick Piggin static int acl_permission_check(struct inode *inode, int mask, unsigned int flags, 180b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 1815909ccaaSLinus Torvalds { 1825909ccaaSLinus Torvalds umode_t mode = inode->i_mode; 1835909ccaaSLinus Torvalds 1845909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 1855909ccaaSLinus Torvalds 1865909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1875909ccaaSLinus Torvalds mode >>= 6; 1885909ccaaSLinus Torvalds else { 1895909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 190b74c79e9SNick Piggin int error = check_acl(inode, mask, flags); 1915909ccaaSLinus Torvalds if (error != -EAGAIN) 1925909ccaaSLinus Torvalds return error; 1935909ccaaSLinus Torvalds } 1945909ccaaSLinus Torvalds 1955909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1965909ccaaSLinus Torvalds mode >>= 3; 1975909ccaaSLinus Torvalds } 1985909ccaaSLinus Torvalds 1995909ccaaSLinus Torvalds /* 2005909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2015909ccaaSLinus Torvalds */ 2025909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 2035909ccaaSLinus Torvalds return 0; 2045909ccaaSLinus Torvalds return -EACCES; 2055909ccaaSLinus Torvalds } 2061da177e4SLinus Torvalds 2071da177e4SLinus Torvalds /** 2081da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2091da177e4SLinus Torvalds * @inode: inode to check access rights for 2101da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2111da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 21239191628SRandy Dunlap * @flags: IPERM_FLAG_ flags. 2131da177e4SLinus Torvalds * 2141da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2151da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2161da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 217b74c79e9SNick Piggin * are used for other things. 218b74c79e9SNick Piggin * 219b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 220b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 221b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2221da177e4SLinus Torvalds */ 223b74c79e9SNick Piggin int generic_permission(struct inode *inode, int mask, unsigned int flags, 224b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 2251da177e4SLinus Torvalds { 2265909ccaaSLinus Torvalds int ret; 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds /* 2295909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2301da177e4SLinus Torvalds */ 231b74c79e9SNick Piggin ret = acl_permission_check(inode, mask, flags, check_acl); 2325909ccaaSLinus Torvalds if (ret != -EACCES) 2335909ccaaSLinus Torvalds return ret; 2341da177e4SLinus Torvalds 2351da177e4SLinus Torvalds /* 2361da177e4SLinus Torvalds * Read/write DACs are always overridable. 2371da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2381da177e4SLinus Torvalds */ 239f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2401da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2411da177e4SLinus Torvalds return 0; 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds /* 2441da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2451da177e4SLinus Torvalds */ 2467ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2471da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2481da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2491da177e4SLinus Torvalds return 0; 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds return -EACCES; 2521da177e4SLinus Torvalds } 2531da177e4SLinus Torvalds 254cb23beb5SChristoph Hellwig /** 255cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 256cb23beb5SChristoph Hellwig * @inode: inode to check permission on 257cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 258cb23beb5SChristoph Hellwig * 259cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 260cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 261cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 262cb23beb5SChristoph Hellwig * are used for other things. 263cb23beb5SChristoph Hellwig */ 264f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2651da177e4SLinus Torvalds { 266e6305c43SAl Viro int retval; 2671da177e4SLinus Torvalds 2681da177e4SLinus Torvalds if (mask & MAY_WRITE) { 26922590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds /* 2721da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2731da177e4SLinus Torvalds */ 2741da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2751da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2761da177e4SLinus Torvalds return -EROFS; 2771da177e4SLinus Torvalds 2781da177e4SLinus Torvalds /* 2791da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2801da177e4SLinus Torvalds */ 2811da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2821da177e4SLinus Torvalds return -EACCES; 2831da177e4SLinus Torvalds } 2841da177e4SLinus Torvalds 285acfa4380SAl Viro if (inode->i_op->permission) 286b74c79e9SNick Piggin retval = inode->i_op->permission(inode, mask, 0); 287f696a365SMiklos Szeredi else 288b74c79e9SNick Piggin retval = generic_permission(inode, mask, 0, 289b74c79e9SNick Piggin inode->i_op->check_acl); 290f696a365SMiklos Szeredi 2911da177e4SLinus Torvalds if (retval) 2921da177e4SLinus Torvalds return retval; 2931da177e4SLinus Torvalds 29408ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 29508ce5f16SSerge E. Hallyn if (retval) 29608ce5f16SSerge E. Hallyn return retval; 29708ce5f16SSerge E. Hallyn 298d09ca739SEric Paris return security_inode_permission(inode, mask); 2991da177e4SLinus Torvalds } 3001da177e4SLinus Torvalds 301e4543eddSChristoph Hellwig /** 3028c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 3038c744fb8SChristoph Hellwig * @file: file to check access rights for 3048c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3058c744fb8SChristoph Hellwig * 3068c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3078c744fb8SChristoph Hellwig * file. 3088c744fb8SChristoph Hellwig * 3098c744fb8SChristoph Hellwig * Note: 3108c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 311cb23beb5SChristoph Hellwig * be done using inode_permission(). 3128c744fb8SChristoph Hellwig */ 3138c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3148c744fb8SChristoph Hellwig { 315f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3168c744fb8SChristoph Hellwig } 3178c744fb8SChristoph Hellwig 3181da177e4SLinus Torvalds /* 3191da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3201da177e4SLinus Torvalds * put_write_access() releases this write permission. 3211da177e4SLinus Torvalds * This is used for regular files. 3221da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3231da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3241da177e4SLinus Torvalds * can have the following values: 3251da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3261da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3271da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3281da177e4SLinus Torvalds * 3291da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3301da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3311da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3321da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3331da177e4SLinus Torvalds * the inode->i_lock spinlock. 3341da177e4SLinus Torvalds */ 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3371da177e4SLinus Torvalds { 3381da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3391da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3401da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3411da177e4SLinus Torvalds return -ETXTBSY; 3421da177e4SLinus Torvalds } 3431da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3441da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds return 0; 3471da177e4SLinus Torvalds } 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds int deny_write_access(struct file * file) 3501da177e4SLinus Torvalds { 3510f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3541da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3551da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3561da177e4SLinus Torvalds return -ETXTBSY; 3571da177e4SLinus Torvalds } 3581da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3591da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3601da177e4SLinus Torvalds 3611da177e4SLinus Torvalds return 0; 3621da177e4SLinus Torvalds } 3631da177e4SLinus Torvalds 3641d957f9bSJan Blunck /** 3655dd784d0SJan Blunck * path_get - get a reference to a path 3665dd784d0SJan Blunck * @path: path to get the reference to 3675dd784d0SJan Blunck * 3685dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3695dd784d0SJan Blunck */ 3705dd784d0SJan Blunck void path_get(struct path *path) 3715dd784d0SJan Blunck { 3725dd784d0SJan Blunck mntget(path->mnt); 3735dd784d0SJan Blunck dget(path->dentry); 3745dd784d0SJan Blunck } 3755dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3765dd784d0SJan Blunck 3775dd784d0SJan Blunck /** 3781d957f9bSJan Blunck * path_put - put a reference to a path 3791d957f9bSJan Blunck * @path: path to put the reference to 3801d957f9bSJan Blunck * 3811d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3821d957f9bSJan Blunck */ 3831d957f9bSJan Blunck void path_put(struct path *path) 3841da177e4SLinus Torvalds { 3851d957f9bSJan Blunck dput(path->dentry); 3861d957f9bSJan Blunck mntput(path->mnt); 3871da177e4SLinus Torvalds } 3881d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3891da177e4SLinus Torvalds 390834f2a4aSTrond Myklebust /** 39131e6b01fSNick Piggin * nameidata_drop_rcu - drop this nameidata out of rcu-walk 39231e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 39339191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 39431e6b01fSNick Piggin * 39531e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 39631e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). __drop_rcu* functions attempt 39731e6b01fSNick Piggin * to drop out of rcu-walk mode and take normal reference counts on dentries 39831e6b01fSNick Piggin * and vfsmounts to transition to rcu-walk mode. __drop_rcu* functions take 39931e6b01fSNick Piggin * refcounts at the last known good point before rcu-walk got stuck, so 40031e6b01fSNick Piggin * ref-walk may continue from there. If this is not successful (eg. a seqcount 40131e6b01fSNick Piggin * has changed), then failure is returned and path walk restarts from the 40231e6b01fSNick Piggin * beginning in ref-walk mode. 40331e6b01fSNick Piggin * 40431e6b01fSNick Piggin * nameidata_drop_rcu attempts to drop the current nd->path and nd->root into 40531e6b01fSNick Piggin * ref-walk. Must be called from rcu-walk context. 40631e6b01fSNick Piggin */ 40731e6b01fSNick Piggin static int nameidata_drop_rcu(struct nameidata *nd) 40831e6b01fSNick Piggin { 40931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 41031e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 4115b6ca027SAl Viro int want_root = 0; 41231e6b01fSNick Piggin 41331e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4145b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4155b6ca027SAl Viro want_root = 1; 41631e6b01fSNick Piggin spin_lock(&fs->lock); 41731e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 41831e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 41931e6b01fSNick Piggin goto err_root; 42031e6b01fSNick Piggin } 42131e6b01fSNick Piggin spin_lock(&dentry->d_lock); 42231e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 42331e6b01fSNick Piggin goto err; 42431e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 42531e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 4265b6ca027SAl Viro if (want_root) { 42731e6b01fSNick Piggin path_get(&nd->root); 42831e6b01fSNick Piggin spin_unlock(&fs->lock); 42931e6b01fSNick Piggin } 43031e6b01fSNick Piggin mntget(nd->path.mnt); 43131e6b01fSNick Piggin 43231e6b01fSNick Piggin rcu_read_unlock(); 43331e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 43431e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 43531e6b01fSNick Piggin return 0; 43631e6b01fSNick Piggin err: 43731e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 43831e6b01fSNick Piggin err_root: 4395b6ca027SAl Viro if (want_root) 44031e6b01fSNick Piggin spin_unlock(&fs->lock); 44131e6b01fSNick Piggin return -ECHILD; 44231e6b01fSNick Piggin } 44331e6b01fSNick Piggin 44431e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 44531e6b01fSNick Piggin static inline int nameidata_drop_rcu_maybe(struct nameidata *nd) 44631e6b01fSNick Piggin { 44731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) 44831e6b01fSNick Piggin return nameidata_drop_rcu(nd); 44931e6b01fSNick Piggin return 0; 45031e6b01fSNick Piggin } 45131e6b01fSNick Piggin 45231e6b01fSNick Piggin /** 45331e6b01fSNick Piggin * nameidata_dentry_drop_rcu - drop nameidata and dentry out of rcu-walk 45431e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 45531e6b01fSNick Piggin * @dentry: dentry to drop 45639191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 45731e6b01fSNick Piggin * 45831e6b01fSNick Piggin * nameidata_dentry_drop_rcu attempts to drop the current nd->path and nd->root, 45931e6b01fSNick Piggin * and dentry into ref-walk. @dentry must be a path found by a do_lookup call on 46031e6b01fSNick Piggin * @nd. Must be called from rcu-walk context. 46131e6b01fSNick Piggin */ 46231e6b01fSNick Piggin static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry) 46331e6b01fSNick Piggin { 46431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 46531e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4665b6ca027SAl Viro int want_root = 0; 46731e6b01fSNick Piggin 46831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4695b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4705b6ca027SAl Viro want_root = 1; 47131e6b01fSNick Piggin spin_lock(&fs->lock); 47231e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 47331e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 47431e6b01fSNick Piggin goto err_root; 47531e6b01fSNick Piggin } 47631e6b01fSNick Piggin spin_lock(&parent->d_lock); 47731e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 47831e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 47931e6b01fSNick Piggin goto err; 48031e6b01fSNick Piggin /* 48131e6b01fSNick Piggin * If the sequence check on the child dentry passed, then the child has 48231e6b01fSNick Piggin * not been removed from its parent. This means the parent dentry must 48331e6b01fSNick Piggin * be valid and able to take a reference at this point. 48431e6b01fSNick Piggin */ 48531e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 48631e6b01fSNick Piggin BUG_ON(!parent->d_count); 48731e6b01fSNick Piggin parent->d_count++; 48831e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 48931e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4905b6ca027SAl Viro if (want_root) { 49131e6b01fSNick Piggin path_get(&nd->root); 49231e6b01fSNick Piggin spin_unlock(&fs->lock); 49331e6b01fSNick Piggin } 49431e6b01fSNick Piggin mntget(nd->path.mnt); 49531e6b01fSNick Piggin 49631e6b01fSNick Piggin rcu_read_unlock(); 49731e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 49831e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 49931e6b01fSNick Piggin return 0; 50031e6b01fSNick Piggin err: 50131e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 50231e6b01fSNick Piggin spin_unlock(&parent->d_lock); 50331e6b01fSNick Piggin err_root: 5045b6ca027SAl Viro if (want_root) 50531e6b01fSNick Piggin spin_unlock(&fs->lock); 50631e6b01fSNick Piggin return -ECHILD; 50731e6b01fSNick Piggin } 50831e6b01fSNick Piggin 50931e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 51031e6b01fSNick Piggin static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry) 51131e6b01fSNick Piggin { 512a7472babSAl Viro if (nd->flags & LOOKUP_RCU) { 513a7472babSAl Viro if (unlikely(nameidata_dentry_drop_rcu(nd, dentry))) { 514a7472babSAl Viro nd->flags &= ~LOOKUP_RCU; 5155b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 516a7472babSAl Viro nd->root.mnt = NULL; 517a7472babSAl Viro rcu_read_unlock(); 518a7472babSAl Viro br_read_unlock(vfsmount_lock); 519a7472babSAl Viro return -ECHILD; 520a7472babSAl Viro } 521a7472babSAl Viro } 52231e6b01fSNick Piggin return 0; 52331e6b01fSNick Piggin } 52431e6b01fSNick Piggin 52531e6b01fSNick Piggin /** 52631e6b01fSNick Piggin * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk 52731e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 52839191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 52931e6b01fSNick Piggin * 53031e6b01fSNick Piggin * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. 53131e6b01fSNick Piggin * nd->path should be the final element of the lookup, so nd->root is discarded. 53231e6b01fSNick Piggin * Must be called from rcu-walk context. 53331e6b01fSNick Piggin */ 53431e6b01fSNick Piggin static int nameidata_drop_rcu_last(struct nameidata *nd) 53531e6b01fSNick Piggin { 53631e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 53731e6b01fSNick Piggin 53831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 53931e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 5405b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 54131e6b01fSNick Piggin nd->root.mnt = NULL; 54231e6b01fSNick Piggin spin_lock(&dentry->d_lock); 54331e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 54431e6b01fSNick Piggin goto err_unlock; 54531e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 54631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 54731e6b01fSNick Piggin 54831e6b01fSNick Piggin mntget(nd->path.mnt); 54931e6b01fSNick Piggin 55031e6b01fSNick Piggin rcu_read_unlock(); 55131e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 55231e6b01fSNick Piggin 55331e6b01fSNick Piggin return 0; 55431e6b01fSNick Piggin 55531e6b01fSNick Piggin err_unlock: 55631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 55731e6b01fSNick Piggin rcu_read_unlock(); 55831e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 55931e6b01fSNick Piggin return -ECHILD; 56031e6b01fSNick Piggin } 56131e6b01fSNick Piggin 56231e6b01fSNick Piggin /** 563834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 564834f2a4aSTrond Myklebust * @nd: pointer to nameidata 565834f2a4aSTrond Myklebust */ 566834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 567834f2a4aSTrond Myklebust { 5682dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 5692dab5974SLinus Torvalds 5702dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 5712dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 5722dab5974SLinus Torvalds put_filp(file); 573834f2a4aSTrond Myklebust else 5742dab5974SLinus Torvalds fput(file); 5752dab5974SLinus Torvalds } 576834f2a4aSTrond Myklebust } 577834f2a4aSTrond Myklebust 578f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 57934286d66SNick Piggin { 580f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 58134286d66SNick Piggin } 58234286d66SNick Piggin 583f5e1c1c1SAl Viro static struct dentry * 584bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 585bcdc5e01SIan Kent { 586f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 587bcdc5e01SIan Kent if (unlikely(status <= 0)) { 588bcdc5e01SIan Kent /* 589bcdc5e01SIan Kent * The dentry failed validation. 590bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 591bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 592bcdc5e01SIan Kent * to return a fail status. 593bcdc5e01SIan Kent */ 59434286d66SNick Piggin if (status < 0) { 59534286d66SNick Piggin dput(dentry); 59634286d66SNick Piggin dentry = ERR_PTR(status); 597f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 598bcdc5e01SIan Kent dput(dentry); 599bcdc5e01SIan Kent dentry = NULL; 600bcdc5e01SIan Kent } 601bcdc5e01SIan Kent } 602f5e1c1c1SAl Viro return dentry; 603f5e1c1c1SAl Viro } 604f5e1c1c1SAl Viro 6051da177e4SLinus Torvalds /* 60616c2cd71SAl Viro * handle_reval_path - force revalidation of a dentry 60739159de2SJeff Layton * 60839159de2SJeff Layton * In some situations the path walking code will trust dentries without 60939159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 61039159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 61139159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 61239159de2SJeff Layton * a d_revalidate call before proceeding. 61339159de2SJeff Layton * 61439159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 61539159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 61639159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 61739159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 61839159de2SJeff Layton * to the path if necessary. 61939159de2SJeff Layton */ 62016c2cd71SAl Viro static inline int handle_reval_path(struct nameidata *nd) 62139159de2SJeff Layton { 62216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 62339159de2SJeff Layton int status; 62439159de2SJeff Layton 62516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 62639159de2SJeff Layton return 0; 62739159de2SJeff Layton 62816c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 62916c2cd71SAl Viro return 0; 63016c2cd71SAl Viro 63116c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 63216c2cd71SAl Viro return 0; 63316c2cd71SAl Viro 63416c2cd71SAl Viro /* Note: we do not d_invalidate() */ 63534286d66SNick Piggin status = d_revalidate(dentry, nd); 63639159de2SJeff Layton if (status > 0) 63739159de2SJeff Layton return 0; 63839159de2SJeff Layton 63916c2cd71SAl Viro if (!status) 64039159de2SJeff Layton status = -ESTALE; 64116c2cd71SAl Viro 64239159de2SJeff Layton return status; 64339159de2SJeff Layton } 64439159de2SJeff Layton 64539159de2SJeff Layton /* 646b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 647b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 648b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 6491da177e4SLinus Torvalds * 6501da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 651b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 6521da177e4SLinus Torvalds * complete permission check. 6531da177e4SLinus Torvalds */ 654b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 6551da177e4SLinus Torvalds { 6565909ccaaSLinus Torvalds int ret; 6571da177e4SLinus Torvalds 658cb9179eaSLinus Torvalds if (inode->i_op->permission) { 659b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 660b74c79e9SNick Piggin } else { 661b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 662b74c79e9SNick Piggin inode->i_op->check_acl); 663cb9179eaSLinus Torvalds } 664b74c79e9SNick Piggin if (likely(!ret)) 6651da177e4SLinus Torvalds goto ok; 666b74c79e9SNick Piggin if (ret == -ECHILD) 66731e6b01fSNick Piggin return ret; 6681da177e4SLinus Torvalds 669f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 6701da177e4SLinus Torvalds goto ok; 6711da177e4SLinus Torvalds 6725909ccaaSLinus Torvalds return ret; 6731da177e4SLinus Torvalds ok: 674b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 6751da177e4SLinus Torvalds } 6761da177e4SLinus Torvalds 6772a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6782a737871SAl Viro { 679f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 680f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6812a737871SAl Viro } 6822a737871SAl Viro 6836de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6846de88d72SAl Viro 68531e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 68631e6b01fSNick Piggin { 68731e6b01fSNick Piggin if (!nd->root.mnt) { 68831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 689c28cc364SNick Piggin unsigned seq; 690c28cc364SNick Piggin 691c28cc364SNick Piggin do { 692c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 69331e6b01fSNick Piggin nd->root = fs->root; 694c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 69531e6b01fSNick Piggin } 69631e6b01fSNick Piggin } 69731e6b01fSNick Piggin 698f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6991da177e4SLinus Torvalds { 70031e6b01fSNick Piggin int ret; 70131e6b01fSNick Piggin 7021da177e4SLinus Torvalds if (IS_ERR(link)) 7031da177e4SLinus Torvalds goto fail; 7041da177e4SLinus Torvalds 7051da177e4SLinus Torvalds if (*link == '/') { 7062a737871SAl Viro set_root(nd); 7071d957f9bSJan Blunck path_put(&nd->path); 7082a737871SAl Viro nd->path = nd->root; 7092a737871SAl Viro path_get(&nd->root); 71016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 7111da177e4SLinus Torvalds } 71231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 713b4091d5fSChristoph Hellwig 71431e6b01fSNick Piggin ret = link_path_walk(link, nd); 71531e6b01fSNick Piggin return ret; 7161da177e4SLinus Torvalds fail: 7171d957f9bSJan Blunck path_put(&nd->path); 7181da177e4SLinus Torvalds return PTR_ERR(link); 7191da177e4SLinus Torvalds } 7201da177e4SLinus Torvalds 7211d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 722051d3812SIan Kent { 723051d3812SIan Kent dput(path->dentry); 7244ac91378SJan Blunck if (path->mnt != nd->path.mnt) 725051d3812SIan Kent mntput(path->mnt); 726051d3812SIan Kent } 727051d3812SIan Kent 7287b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7297b9337aaSNick Piggin struct nameidata *nd) 730051d3812SIan Kent { 73131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7324ac91378SJan Blunck dput(nd->path.dentry); 73331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7344ac91378SJan Blunck mntput(nd->path.mnt); 7359a229683SHuang Shijie } 73631e6b01fSNick Piggin nd->path.mnt = path->mnt; 7374ac91378SJan Blunck nd->path.dentry = path->dentry; 738051d3812SIan Kent } 739051d3812SIan Kent 740574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 741574197e0SAl Viro { 742574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 743574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 744574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 745574197e0SAl Viro path_put(link); 746574197e0SAl Viro } 747574197e0SAl Viro 748def4af30SAl Viro static __always_inline int 749574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 7501da177e4SLinus Torvalds { 7511da177e4SLinus Torvalds int error; 7527b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7531da177e4SLinus Torvalds 754844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 755844a3917SAl Viro 7560e794589SAl Viro if (link->mnt == nd->path.mnt) 7570e794589SAl Viro mntget(link->mnt); 7580e794589SAl Viro 759574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 760574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 761574197e0SAl Viro path_put(&nd->path); 762574197e0SAl Viro return -ELOOP; 763574197e0SAl Viro } 764574197e0SAl Viro cond_resched(); 765574197e0SAl Viro current->total_link_count++; 766574197e0SAl Viro 7677b9337aaSNick Piggin touch_atime(link->mnt, dentry); 7681da177e4SLinus Torvalds nd_set_link(nd, NULL); 769cd4e91d3SAl Viro 77036f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 77136f3b4f6SAl Viro if (error) { 77236f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 77336f3b4f6SAl Viro path_put(&nd->path); 77436f3b4f6SAl Viro return error; 77536f3b4f6SAl Viro } 77636f3b4f6SAl Viro 77786acdca1SAl Viro nd->last_type = LAST_BIND; 778def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 779def4af30SAl Viro error = PTR_ERR(*p); 780def4af30SAl Viro if (!IS_ERR(*p)) { 7811da177e4SLinus Torvalds char *s = nd_get_link(nd); 782cc314eefSLinus Torvalds error = 0; 7831da177e4SLinus Torvalds if (s) 7841da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 785bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 78616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 787b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 788b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 789bcda7652SAl Viro /* stepped on a _really_ weird one */ 790bcda7652SAl Viro path_put(&nd->path); 791bcda7652SAl Viro error = -ELOOP; 792bcda7652SAl Viro } 793bcda7652SAl Viro } 7941da177e4SLinus Torvalds } 7951da177e4SLinus Torvalds return error; 7961da177e4SLinus Torvalds } 7971da177e4SLinus Torvalds 79831e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 79931e6b01fSNick Piggin { 80031e6b01fSNick Piggin struct vfsmount *parent; 80131e6b01fSNick Piggin struct dentry *mountpoint; 80231e6b01fSNick Piggin 80331e6b01fSNick Piggin parent = path->mnt->mnt_parent; 80431e6b01fSNick Piggin if (parent == path->mnt) 80531e6b01fSNick Piggin return 0; 80631e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 80731e6b01fSNick Piggin path->dentry = mountpoint; 80831e6b01fSNick Piggin path->mnt = parent; 80931e6b01fSNick Piggin return 1; 81031e6b01fSNick Piggin } 81131e6b01fSNick Piggin 812bab77ebfSAl Viro int follow_up(struct path *path) 8131da177e4SLinus Torvalds { 8141da177e4SLinus Torvalds struct vfsmount *parent; 8151da177e4SLinus Torvalds struct dentry *mountpoint; 81699b7db7bSNick Piggin 81799b7db7bSNick Piggin br_read_lock(vfsmount_lock); 818bab77ebfSAl Viro parent = path->mnt->mnt_parent; 819bab77ebfSAl Viro if (parent == path->mnt) { 82099b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 8211da177e4SLinus Torvalds return 0; 8221da177e4SLinus Torvalds } 8231da177e4SLinus Torvalds mntget(parent); 824bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 82599b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 826bab77ebfSAl Viro dput(path->dentry); 827bab77ebfSAl Viro path->dentry = mountpoint; 828bab77ebfSAl Viro mntput(path->mnt); 829bab77ebfSAl Viro path->mnt = parent; 8301da177e4SLinus Torvalds return 1; 8311da177e4SLinus Torvalds } 8321da177e4SLinus Torvalds 833b5c84bf6SNick Piggin /* 8349875cf80SDavid Howells * Perform an automount 8359875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 8369875cf80SDavid Howells * were called with. 8371da177e4SLinus Torvalds */ 8389875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 8399875cf80SDavid Howells bool *need_mntput) 84031e6b01fSNick Piggin { 8419875cf80SDavid Howells struct vfsmount *mnt; 842ea5b778aSDavid Howells int err; 8439875cf80SDavid Howells 8449875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 8459875cf80SDavid Howells return -EREMOTE; 8469875cf80SDavid Howells 8476f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 8486f45b656SDavid Howells * and this is the terminal part of the path. 8496f45b656SDavid Howells */ 8506f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 8516f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 8526f45b656SDavid Howells 8539875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 8549875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 8559875cf80SDavid Howells * or wants to open the mounted directory. 8569875cf80SDavid Howells * 8579875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 8589875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 8599875cf80SDavid Howells * appended a '/' to the name. 8609875cf80SDavid Howells */ 8619875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 8629875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 8639875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 8649875cf80SDavid Howells return -EISDIR; 8659875cf80SDavid Howells 8669875cf80SDavid Howells current->total_link_count++; 8679875cf80SDavid Howells if (current->total_link_count >= 40) 8689875cf80SDavid Howells return -ELOOP; 8699875cf80SDavid Howells 8709875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8719875cf80SDavid Howells if (IS_ERR(mnt)) { 8729875cf80SDavid Howells /* 8739875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8749875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 8759875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 8769875cf80SDavid Howells * 8779875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 8789875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 8799875cf80SDavid Howells * the path is inaccessible and we should say so. 8809875cf80SDavid Howells */ 8819875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 8829875cf80SDavid Howells return -EREMOTE; 8839875cf80SDavid Howells return PTR_ERR(mnt); 88431e6b01fSNick Piggin } 885ea5b778aSDavid Howells 8869875cf80SDavid Howells if (!mnt) /* mount collision */ 8879875cf80SDavid Howells return 0; 8889875cf80SDavid Howells 88919a167afSAl Viro err = finish_automount(mnt, path); 890ea5b778aSDavid Howells 891ea5b778aSDavid Howells switch (err) { 892ea5b778aSDavid Howells case -EBUSY: 893ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 89419a167afSAl Viro return 0; 895ea5b778aSDavid Howells case 0: 896463ffb2eSAl Viro dput(path->dentry); 8979875cf80SDavid Howells if (*need_mntput) 8989875cf80SDavid Howells mntput(path->mnt); 8999875cf80SDavid Howells path->mnt = mnt; 9009875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9019875cf80SDavid Howells *need_mntput = true; 9029875cf80SDavid Howells return 0; 90319a167afSAl Viro default: 90419a167afSAl Viro return err; 9059875cf80SDavid Howells } 90619a167afSAl Viro 907ea5b778aSDavid Howells } 9089875cf80SDavid Howells 9099875cf80SDavid Howells /* 9109875cf80SDavid Howells * Handle a dentry that is managed in some way. 911cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9129875cf80SDavid Howells * - Flagged as mountpoint 9139875cf80SDavid Howells * - Flagged as automount point 9149875cf80SDavid Howells * 9159875cf80SDavid Howells * This may only be called in refwalk mode. 9169875cf80SDavid Howells * 9179875cf80SDavid Howells * Serialization is taken care of in namespace.c 9189875cf80SDavid Howells */ 9199875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9209875cf80SDavid Howells { 9219875cf80SDavid Howells unsigned managed; 9229875cf80SDavid Howells bool need_mntput = false; 9239875cf80SDavid Howells int ret; 9249875cf80SDavid Howells 9259875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9269875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9279875cf80SDavid Howells * the components of that value change under us */ 9289875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9299875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9309875cf80SDavid Howells unlikely(managed != 0)) { 931cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 932cc53ce53SDavid Howells * being held. */ 933cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 934cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 935cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 9361aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 937cc53ce53SDavid Howells if (ret < 0) 938cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 939cc53ce53SDavid Howells } 940cc53ce53SDavid Howells 9419875cf80SDavid Howells /* Transit to a mounted filesystem. */ 9429875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 9439875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9449875cf80SDavid Howells if (mounted) { 9459875cf80SDavid Howells dput(path->dentry); 9469875cf80SDavid Howells if (need_mntput) 947463ffb2eSAl Viro mntput(path->mnt); 948463ffb2eSAl Viro path->mnt = mounted; 949463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 9509875cf80SDavid Howells need_mntput = true; 9519875cf80SDavid Howells continue; 952463ffb2eSAl Viro } 953463ffb2eSAl Viro 9549875cf80SDavid Howells /* Something is mounted on this dentry in another 9559875cf80SDavid Howells * namespace and/or whatever was mounted there in this 9569875cf80SDavid Howells * namespace got unmounted before we managed to get the 9579875cf80SDavid Howells * vfsmount_lock */ 9581da177e4SLinus Torvalds } 9599875cf80SDavid Howells 9609875cf80SDavid Howells /* Handle an automount point */ 9619875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 9629875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 9639875cf80SDavid Howells if (ret < 0) 9649875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 9659875cf80SDavid Howells continue; 9669875cf80SDavid Howells } 9679875cf80SDavid Howells 9689875cf80SDavid Howells /* We didn't change the current path point */ 9699875cf80SDavid Howells break; 9709875cf80SDavid Howells } 9719875cf80SDavid Howells return 0; 9721da177e4SLinus Torvalds } 9731da177e4SLinus Torvalds 974cc53ce53SDavid Howells int follow_down_one(struct path *path) 9751da177e4SLinus Torvalds { 9761da177e4SLinus Torvalds struct vfsmount *mounted; 9771da177e4SLinus Torvalds 9781c755af4SAl Viro mounted = lookup_mnt(path); 9791da177e4SLinus Torvalds if (mounted) { 9809393bd07SAl Viro dput(path->dentry); 9819393bd07SAl Viro mntput(path->mnt); 9829393bd07SAl Viro path->mnt = mounted; 9839393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9841da177e4SLinus Torvalds return 1; 9851da177e4SLinus Torvalds } 9861da177e4SLinus Torvalds return 0; 9871da177e4SLinus Torvalds } 9881da177e4SLinus Torvalds 9899875cf80SDavid Howells /* 9909875cf80SDavid Howells * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we 991cc53ce53SDavid Howells * meet a managed dentry and we're not walking to "..". True is returned to 9929875cf80SDavid Howells * continue, false to abort. 9939875cf80SDavid Howells */ 9949875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 9959875cf80SDavid Howells struct inode **inode, bool reverse_transit) 9969875cf80SDavid Howells { 9979875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 9989875cf80SDavid Howells struct vfsmount *mounted; 999ab90911fSDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) && 1000ab90911fSDavid Howells !reverse_transit && 10011aed3e42SAl Viro path->dentry->d_op->d_manage(path->dentry, true) < 0) 1002ab90911fSDavid Howells return false; 10039875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 10049875cf80SDavid Howells if (!mounted) 10059875cf80SDavid Howells break; 10069875cf80SDavid Howells path->mnt = mounted; 10079875cf80SDavid Howells path->dentry = mounted->mnt_root; 10089875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 10099875cf80SDavid Howells *inode = path->dentry->d_inode; 10109875cf80SDavid Howells } 10119875cf80SDavid Howells 10129875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 10139875cf80SDavid Howells return reverse_transit; 10149875cf80SDavid Howells return true; 10159875cf80SDavid Howells } 10169875cf80SDavid Howells 101731e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 101831e6b01fSNick Piggin { 101931e6b01fSNick Piggin struct inode *inode = nd->inode; 102031e6b01fSNick Piggin 102131e6b01fSNick Piggin set_root_rcu(nd); 102231e6b01fSNick Piggin 102331e6b01fSNick Piggin while (1) { 102431e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 102531e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 102631e6b01fSNick Piggin break; 102731e6b01fSNick Piggin } 102831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 102931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 103031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 103131e6b01fSNick Piggin unsigned seq; 103231e6b01fSNick Piggin 103331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 103431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1035ef7562d5SAl Viro goto failed; 103631e6b01fSNick Piggin inode = parent->d_inode; 103731e6b01fSNick Piggin nd->path.dentry = parent; 103831e6b01fSNick Piggin nd->seq = seq; 103931e6b01fSNick Piggin break; 104031e6b01fSNick Piggin } 104131e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 104231e6b01fSNick Piggin break; 104331e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 104431e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 104531e6b01fSNick Piggin } 10469875cf80SDavid Howells __follow_mount_rcu(nd, &nd->path, &inode, true); 104731e6b01fSNick Piggin nd->inode = inode; 104831e6b01fSNick Piggin return 0; 1049ef7562d5SAl Viro 1050ef7562d5SAl Viro failed: 1051ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 10525b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1053ef7562d5SAl Viro nd->root.mnt = NULL; 1054ef7562d5SAl Viro rcu_read_unlock(); 1055ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 1056ef7562d5SAl Viro return -ECHILD; 105731e6b01fSNick Piggin } 105831e6b01fSNick Piggin 10599875cf80SDavid Howells /* 1060cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1061cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1062cc53ce53SDavid Howells * caller is permitted to proceed or not. 1063cc53ce53SDavid Howells * 1064cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1065cc53ce53SDavid Howells * being true). 1066cc53ce53SDavid Howells */ 10677cc90cc3SAl Viro int follow_down(struct path *path) 1068cc53ce53SDavid Howells { 1069cc53ce53SDavid Howells unsigned managed; 1070cc53ce53SDavid Howells int ret; 1071cc53ce53SDavid Howells 1072cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1073cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1074cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1075cc53ce53SDavid Howells * being held. 1076cc53ce53SDavid Howells * 1077cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1078cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1079cc53ce53SDavid Howells * other than its daemon the right to mount on its 1080cc53ce53SDavid Howells * superstructure. 1081cc53ce53SDavid Howells * 1082cc53ce53SDavid Howells * The filesystem may sleep at this point. 1083cc53ce53SDavid Howells */ 1084cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1085cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1086cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1087ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 10881aed3e42SAl Viro path->dentry, false); 1089cc53ce53SDavid Howells if (ret < 0) 1090cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1091cc53ce53SDavid Howells } 1092cc53ce53SDavid Howells 1093cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1094cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1095cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1096cc53ce53SDavid Howells if (!mounted) 1097cc53ce53SDavid Howells break; 1098cc53ce53SDavid Howells dput(path->dentry); 1099cc53ce53SDavid Howells mntput(path->mnt); 1100cc53ce53SDavid Howells path->mnt = mounted; 1101cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1102cc53ce53SDavid Howells continue; 1103cc53ce53SDavid Howells } 1104cc53ce53SDavid Howells 1105cc53ce53SDavid Howells /* Don't handle automount points here */ 1106cc53ce53SDavid Howells break; 1107cc53ce53SDavid Howells } 1108cc53ce53SDavid Howells return 0; 1109cc53ce53SDavid Howells } 1110cc53ce53SDavid Howells 1111cc53ce53SDavid Howells /* 11129875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 11139875cf80SDavid Howells */ 11149875cf80SDavid Howells static void follow_mount(struct path *path) 11159875cf80SDavid Howells { 11169875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11179875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11189875cf80SDavid Howells if (!mounted) 11199875cf80SDavid Howells break; 11209875cf80SDavid Howells dput(path->dentry); 11219875cf80SDavid Howells mntput(path->mnt); 11229875cf80SDavid Howells path->mnt = mounted; 11239875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11249875cf80SDavid Howells } 11259875cf80SDavid Howells } 11269875cf80SDavid Howells 112731e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11281da177e4SLinus Torvalds { 11292a737871SAl Viro set_root(nd); 1130e518ddb7SAndreas Mohr 11311da177e4SLinus Torvalds while(1) { 11324ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11331da177e4SLinus Torvalds 11342a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11352a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11361da177e4SLinus Torvalds break; 11371da177e4SLinus Torvalds } 11384ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11393088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11403088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11411da177e4SLinus Torvalds dput(old); 11421da177e4SLinus Torvalds break; 11431da177e4SLinus Torvalds } 11443088dd70SAl Viro if (!follow_up(&nd->path)) 11451da177e4SLinus Torvalds break; 11461da177e4SLinus Torvalds } 114779ed0226SAl Viro follow_mount(&nd->path); 114831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11491da177e4SLinus Torvalds } 11501da177e4SLinus Torvalds 11511da177e4SLinus Torvalds /* 1152baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1153baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1154baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1155baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1156baa03890SNick Piggin */ 1157baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1158baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1159baa03890SNick Piggin { 1160baa03890SNick Piggin struct inode *inode = parent->d_inode; 1161baa03890SNick Piggin struct dentry *dentry; 1162baa03890SNick Piggin struct dentry *old; 1163baa03890SNick Piggin 1164baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1165baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1166baa03890SNick Piggin return ERR_PTR(-ENOENT); 1167baa03890SNick Piggin 1168baa03890SNick Piggin dentry = d_alloc(parent, name); 1169baa03890SNick Piggin if (unlikely(!dentry)) 1170baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1171baa03890SNick Piggin 1172baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1173baa03890SNick Piggin if (unlikely(old)) { 1174baa03890SNick Piggin dput(dentry); 1175baa03890SNick Piggin dentry = old; 1176baa03890SNick Piggin } 1177baa03890SNick Piggin return dentry; 1178baa03890SNick Piggin } 1179baa03890SNick Piggin 1180baa03890SNick Piggin /* 11811da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11821da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11831da177e4SLinus Torvalds * It _is_ time-critical. 11841da177e4SLinus Torvalds */ 11851da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 118631e6b01fSNick Piggin struct path *path, struct inode **inode) 11871da177e4SLinus Torvalds { 11884ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 118931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11905a18fff2SAl Viro int need_reval = 1; 11915a18fff2SAl Viro int status = 1; 11929875cf80SDavid Howells int err; 11939875cf80SDavid Howells 11943cac260aSAl Viro /* 1195b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1196b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1197b04f784eSNick Piggin * do the non-racy lookup, below. 1198b04f784eSNick Piggin */ 119931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 120031e6b01fSNick Piggin unsigned seq; 120131e6b01fSNick Piggin *inode = nd->inode; 120231e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 12035a18fff2SAl Viro if (!dentry) 12045a18fff2SAl Viro goto unlazy; 12055a18fff2SAl Viro 120631e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 120731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 120831e6b01fSNick Piggin return -ECHILD; 120931e6b01fSNick Piggin nd->seq = seq; 12105a18fff2SAl Viro 121124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 12125a18fff2SAl Viro status = d_revalidate(dentry, nd); 12135a18fff2SAl Viro if (unlikely(status <= 0)) { 12145a18fff2SAl Viro if (status != -ECHILD) 12155a18fff2SAl Viro need_reval = 0; 12165a18fff2SAl Viro goto unlazy; 12175a18fff2SAl Viro } 121824643087SAl Viro } 121931e6b01fSNick Piggin path->mnt = mnt; 122031e6b01fSNick Piggin path->dentry = dentry; 12219875cf80SDavid Howells if (likely(__follow_mount_rcu(nd, path, inode, false))) 12229875cf80SDavid Howells return 0; 12235a18fff2SAl Viro unlazy: 12245a18fff2SAl Viro if (dentry) { 12255a18fff2SAl Viro if (nameidata_dentry_drop_rcu(nd, dentry)) 12265a18fff2SAl Viro return -ECHILD; 12275a18fff2SAl Viro } else { 12289875cf80SDavid Howells if (nameidata_drop_rcu(nd)) 12299875cf80SDavid Howells return -ECHILD; 12309875cf80SDavid Howells } 12315a18fff2SAl Viro } else { 123231e6b01fSNick Piggin dentry = __d_lookup(parent, name); 123324643087SAl Viro } 12345a18fff2SAl Viro 12355a18fff2SAl Viro retry: 12365a18fff2SAl Viro if (unlikely(!dentry)) { 12375a18fff2SAl Viro struct inode *dir = parent->d_inode; 12385a18fff2SAl Viro BUG_ON(nd->inode != dir); 12395a18fff2SAl Viro 12405a18fff2SAl Viro mutex_lock(&dir->i_mutex); 12415a18fff2SAl Viro dentry = d_lookup(parent, name); 12425a18fff2SAl Viro if (likely(!dentry)) { 12435a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 12445a18fff2SAl Viro if (IS_ERR(dentry)) { 12455a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12465a18fff2SAl Viro return PTR_ERR(dentry); 12475a18fff2SAl Viro } 12485a18fff2SAl Viro /* known good */ 12495a18fff2SAl Viro need_reval = 0; 12505a18fff2SAl Viro status = 1; 12515a18fff2SAl Viro } 12525a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12535a18fff2SAl Viro } 12545a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12555a18fff2SAl Viro status = d_revalidate(dentry, nd); 12565a18fff2SAl Viro if (unlikely(status <= 0)) { 12575a18fff2SAl Viro if (status < 0) { 12585a18fff2SAl Viro dput(dentry); 12595a18fff2SAl Viro return status; 12605a18fff2SAl Viro } 12615a18fff2SAl Viro if (!d_invalidate(dentry)) { 12625a18fff2SAl Viro dput(dentry); 12635a18fff2SAl Viro dentry = NULL; 12645a18fff2SAl Viro need_reval = 1; 12655a18fff2SAl Viro goto retry; 12665a18fff2SAl Viro } 12675a18fff2SAl Viro } 12685a18fff2SAl Viro 12691da177e4SLinus Torvalds path->mnt = mnt; 12701da177e4SLinus Torvalds path->dentry = dentry; 12719875cf80SDavid Howells err = follow_managed(path, nd->flags); 127289312214SIan Kent if (unlikely(err < 0)) { 127389312214SIan Kent path_put_conditional(path, nd); 12749875cf80SDavid Howells return err; 127589312214SIan Kent } 127631e6b01fSNick Piggin *inode = path->dentry->d_inode; 12771da177e4SLinus Torvalds return 0; 12781da177e4SLinus Torvalds } 12791da177e4SLinus Torvalds 128052094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 128152094c8aSAl Viro { 128252094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 128352094c8aSAl Viro int err = exec_permission(nd->inode, IPERM_FLAG_RCU); 128452094c8aSAl Viro if (err != -ECHILD) 128552094c8aSAl Viro return err; 128652094c8aSAl Viro if (nameidata_drop_rcu(nd)) 128752094c8aSAl Viro return -ECHILD; 128852094c8aSAl Viro } 128952094c8aSAl Viro return exec_permission(nd->inode, 0); 129052094c8aSAl Viro } 129152094c8aSAl Viro 12929856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12939856fa1bSAl Viro { 12949856fa1bSAl Viro if (type == LAST_DOTDOT) { 12959856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12969856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12979856fa1bSAl Viro return -ECHILD; 12989856fa1bSAl Viro } else 12999856fa1bSAl Viro follow_dotdot(nd); 13009856fa1bSAl Viro } 13019856fa1bSAl Viro return 0; 13029856fa1bSAl Viro } 13039856fa1bSAl Viro 1304951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1305951361f9SAl Viro { 1306951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1307951361f9SAl Viro path_put(&nd->path); 1308951361f9SAl Viro } else { 1309951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 13105b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1311951361f9SAl Viro nd->root.mnt = NULL; 1312951361f9SAl Viro rcu_read_unlock(); 1313951361f9SAl Viro br_read_unlock(vfsmount_lock); 1314951361f9SAl Viro } 1315951361f9SAl Viro } 1316951361f9SAl Viro 1317ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1318ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1319ce57dfc1SAl Viro { 1320ce57dfc1SAl Viro struct inode *inode; 1321ce57dfc1SAl Viro int err; 1322ce57dfc1SAl Viro /* 1323ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1324ce57dfc1SAl Viro * to be able to know about the current root directory and 1325ce57dfc1SAl Viro * parent relationships. 1326ce57dfc1SAl Viro */ 1327ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1328ce57dfc1SAl Viro return handle_dots(nd, type); 1329ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1330ce57dfc1SAl Viro if (unlikely(err)) { 1331ce57dfc1SAl Viro terminate_walk(nd); 1332ce57dfc1SAl Viro return err; 1333ce57dfc1SAl Viro } 1334ce57dfc1SAl Viro if (!inode) { 1335ce57dfc1SAl Viro path_to_nameidata(path, nd); 1336ce57dfc1SAl Viro terminate_walk(nd); 1337ce57dfc1SAl Viro return -ENOENT; 1338ce57dfc1SAl Viro } 1339ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 1340ce57dfc1SAl Viro if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry)) 1341ce57dfc1SAl Viro return -ECHILD; 1342ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1343ce57dfc1SAl Viro return 1; 1344ce57dfc1SAl Viro } 1345ce57dfc1SAl Viro path_to_nameidata(path, nd); 1346ce57dfc1SAl Viro nd->inode = inode; 1347ce57dfc1SAl Viro return 0; 1348ce57dfc1SAl Viro } 1349ce57dfc1SAl Viro 13501da177e4SLinus Torvalds /* 1351b356379aSAl Viro * This limits recursive symlink follows to 8, while 1352b356379aSAl Viro * limiting consecutive symlinks to 40. 1353b356379aSAl Viro * 1354b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1355b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1356b356379aSAl Viro */ 1357b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1358b356379aSAl Viro { 1359b356379aSAl Viro int res; 1360b356379aSAl Viro 1361b356379aSAl Viro BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1362b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1363b356379aSAl Viro path_put_conditional(path, nd); 1364b356379aSAl Viro path_put(&nd->path); 1365b356379aSAl Viro return -ELOOP; 1366b356379aSAl Viro } 1367b356379aSAl Viro 1368b356379aSAl Viro nd->depth++; 1369b356379aSAl Viro current->link_count++; 1370b356379aSAl Viro 1371b356379aSAl Viro do { 1372b356379aSAl Viro struct path link = *path; 1373b356379aSAl Viro void *cookie; 1374574197e0SAl Viro 1375574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1376b356379aSAl Viro if (!res) 1377b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1378b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1379574197e0SAl Viro put_link(nd, &link, cookie); 1380b356379aSAl Viro } while (res > 0); 1381b356379aSAl Viro 1382b356379aSAl Viro current->link_count--; 1383b356379aSAl Viro nd->depth--; 1384b356379aSAl Viro return res; 1385b356379aSAl Viro } 1386b356379aSAl Viro 1387b356379aSAl Viro /* 13881da177e4SLinus Torvalds * Name resolution. 1389ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1390ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13911da177e4SLinus Torvalds * 1392ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1393ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13941da177e4SLinus Torvalds */ 13956de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13961da177e4SLinus Torvalds { 13971da177e4SLinus Torvalds struct path next; 13981da177e4SLinus Torvalds int err; 13991da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds while (*name=='/') 14021da177e4SLinus Torvalds name++; 14031da177e4SLinus Torvalds if (!*name) 1404086e183aSAl Viro return 0; 14051da177e4SLinus Torvalds 14061da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 14071da177e4SLinus Torvalds for(;;) { 14081da177e4SLinus Torvalds unsigned long hash; 14091da177e4SLinus Torvalds struct qstr this; 14101da177e4SLinus Torvalds unsigned int c; 1411fe479a58SAl Viro int type; 14121da177e4SLinus Torvalds 1413cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 141452094c8aSAl Viro 141552094c8aSAl Viro err = may_lookup(nd); 14161da177e4SLinus Torvalds if (err) 14171da177e4SLinus Torvalds break; 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds this.name = name; 14201da177e4SLinus Torvalds c = *(const unsigned char *)name; 14211da177e4SLinus Torvalds 14221da177e4SLinus Torvalds hash = init_name_hash(); 14231da177e4SLinus Torvalds do { 14241da177e4SLinus Torvalds name++; 14251da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 14261da177e4SLinus Torvalds c = *(const unsigned char *)name; 14271da177e4SLinus Torvalds } while (c && (c != '/')); 14281da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14291da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14301da177e4SLinus Torvalds 1431fe479a58SAl Viro type = LAST_NORM; 1432fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1433fe479a58SAl Viro case 2: 143416c2cd71SAl Viro if (this.name[1] == '.') { 1435fe479a58SAl Viro type = LAST_DOTDOT; 143616c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 143716c2cd71SAl Viro } 1438fe479a58SAl Viro break; 1439fe479a58SAl Viro case 1: 1440fe479a58SAl Viro type = LAST_DOT; 1441fe479a58SAl Viro } 14425a202bcdSAl Viro if (likely(type == LAST_NORM)) { 14435a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 144416c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14455a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14465a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14475a202bcdSAl Viro &this); 14485a202bcdSAl Viro if (err < 0) 14495a202bcdSAl Viro break; 14505a202bcdSAl Viro } 14515a202bcdSAl Viro } 1452fe479a58SAl Viro 14531da177e4SLinus Torvalds /* remove trailing slashes? */ 14541da177e4SLinus Torvalds if (!c) 14551da177e4SLinus Torvalds goto last_component; 14561da177e4SLinus Torvalds while (*++name == '/'); 14571da177e4SLinus Torvalds if (!*name) 1458b356379aSAl Viro goto last_component; 14591da177e4SLinus Torvalds 1460ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1461ce57dfc1SAl Viro if (err < 0) 1462ce57dfc1SAl Viro return err; 1463fe479a58SAl Viro 1464ce57dfc1SAl Viro if (err) { 1465b356379aSAl Viro err = nested_symlink(&next, nd); 14661da177e4SLinus Torvalds if (err) 1467a7472babSAl Viro return err; 146831e6b01fSNick Piggin } 14691da177e4SLinus Torvalds err = -ENOTDIR; 147031e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14711da177e4SLinus Torvalds break; 14721da177e4SLinus Torvalds continue; 14731da177e4SLinus Torvalds /* here ends the main loop */ 14741da177e4SLinus Torvalds 14751da177e4SLinus Torvalds last_component: 1476f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1477f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1478ce57dfc1SAl Viro nd->last = this; 1479ce57dfc1SAl Viro nd->last_type = type; 1480ce57dfc1SAl Viro return 0; 1481ce57dfc1SAl Viro } 1482951361f9SAl Viro terminate_walk(nd); 14831da177e4SLinus Torvalds return err; 14841da177e4SLinus Torvalds } 14851da177e4SLinus Torvalds 148670e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 148770e9b357SAl Viro struct nameidata *nd, struct file **fp) 148831e6b01fSNick Piggin { 148931e6b01fSNick Piggin int retval = 0; 149031e6b01fSNick Piggin int fput_needed; 149131e6b01fSNick Piggin struct file *file; 149231e6b01fSNick Piggin 149331e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 149416c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 149531e6b01fSNick Piggin nd->depth = 0; 14965b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14975b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 149873d049a4SAl Viro if (*name) { 14995b6ca027SAl Viro if (!inode->i_op->lookup) 15005b6ca027SAl Viro return -ENOTDIR; 15015b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 15025b6ca027SAl Viro if (retval) 15035b6ca027SAl Viro return retval; 150473d049a4SAl Viro } 15055b6ca027SAl Viro nd->path = nd->root; 15065b6ca027SAl Viro nd->inode = inode; 15075b6ca027SAl Viro if (flags & LOOKUP_RCU) { 15085b6ca027SAl Viro br_read_lock(vfsmount_lock); 15095b6ca027SAl Viro rcu_read_lock(); 15105b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 15115b6ca027SAl Viro } else { 15125b6ca027SAl Viro path_get(&nd->path); 15135b6ca027SAl Viro } 15145b6ca027SAl Viro return 0; 15155b6ca027SAl Viro } 15165b6ca027SAl Viro 151731e6b01fSNick Piggin nd->root.mnt = NULL; 151831e6b01fSNick Piggin 151931e6b01fSNick Piggin if (*name=='/') { 1520e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 152131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 152231e6b01fSNick Piggin rcu_read_lock(); 1523e41f7d4eSAl Viro set_root_rcu(nd); 1524e41f7d4eSAl Viro } else { 1525e41f7d4eSAl Viro set_root(nd); 1526e41f7d4eSAl Viro path_get(&nd->root); 1527e41f7d4eSAl Viro } 152831e6b01fSNick Piggin nd->path = nd->root; 152931e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1530e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 153131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1532c28cc364SNick Piggin unsigned seq; 153331e6b01fSNick Piggin 153431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 153531e6b01fSNick Piggin rcu_read_lock(); 153631e6b01fSNick Piggin 1537c28cc364SNick Piggin do { 1538c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 153931e6b01fSNick Piggin nd->path = fs->pwd; 1540c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1541c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1542e41f7d4eSAl Viro } else { 1543e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1544e41f7d4eSAl Viro } 154531e6b01fSNick Piggin } else { 154631e6b01fSNick Piggin struct dentry *dentry; 154731e6b01fSNick Piggin 15481abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 154931e6b01fSNick Piggin retval = -EBADF; 155031e6b01fSNick Piggin if (!file) 155131e6b01fSNick Piggin goto out_fail; 155231e6b01fSNick Piggin 155331e6b01fSNick Piggin dentry = file->f_path.dentry; 155431e6b01fSNick Piggin 1555f52e0c11SAl Viro if (*name) { 155631e6b01fSNick Piggin retval = -ENOTDIR; 155731e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 155831e6b01fSNick Piggin goto fput_fail; 155931e6b01fSNick Piggin 156031e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 156131e6b01fSNick Piggin if (retval) 156231e6b01fSNick Piggin goto fput_fail; 1563f52e0c11SAl Viro } 156431e6b01fSNick Piggin 156531e6b01fSNick Piggin nd->path = file->f_path; 1566e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 156731e6b01fSNick Piggin if (fput_needed) 156870e9b357SAl Viro *fp = file; 1569c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 157031e6b01fSNick Piggin br_read_lock(vfsmount_lock); 157131e6b01fSNick Piggin rcu_read_lock(); 15725590ff0dSUlrich Drepper } else { 15735dd784d0SJan Blunck path_get(&file->f_path); 15745590ff0dSUlrich Drepper fput_light(file, fput_needed); 15751da177e4SLinus Torvalds } 1576e41f7d4eSAl Viro } 1577e41f7d4eSAl Viro 157831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15799b4a9b14SAl Viro return 0; 15802dfdd266SJosef 'Jeff' Sipek 15819b4a9b14SAl Viro fput_fail: 15829b4a9b14SAl Viro fput_light(file, fput_needed); 15839b4a9b14SAl Viro out_fail: 15849b4a9b14SAl Viro return retval; 15859b4a9b14SAl Viro } 15869b4a9b14SAl Viro 1587bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1588bd92d7feSAl Viro { 1589bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1590bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1591bd92d7feSAl Viro 1592bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1593bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1594bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1595bd92d7feSAl Viro } 1596bd92d7feSAl Viro 15979b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1598ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15999b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 16009b4a9b14SAl Viro { 160170e9b357SAl Viro struct file *base = NULL; 1602bd92d7feSAl Viro struct path path; 1603bd92d7feSAl Viro int err; 160431e6b01fSNick Piggin 160531e6b01fSNick Piggin /* 160631e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 160731e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 160831e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 160931e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 161031e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 161131e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 161231e6b01fSNick Piggin * analogue, foo_rcu(). 161331e6b01fSNick Piggin * 161431e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 161531e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 161631e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 161731e6b01fSNick Piggin * be able to complete). 161831e6b01fSNick Piggin */ 1619bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1620ee0827cdSAl Viro 1621bd92d7feSAl Viro if (unlikely(err)) 1622bd92d7feSAl Viro return err; 1623ee0827cdSAl Viro 1624ee0827cdSAl Viro current->total_link_count = 0; 1625bd92d7feSAl Viro err = link_path_walk(name, nd); 1626bd92d7feSAl Viro 1627bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1628bd92d7feSAl Viro err = lookup_last(nd, &path); 1629bd92d7feSAl Viro while (err > 0) { 1630bd92d7feSAl Viro void *cookie; 1631bd92d7feSAl Viro struct path link = path; 1632bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1633574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1634bd92d7feSAl Viro if (!err) 1635bd92d7feSAl Viro err = lookup_last(nd, &path); 1636574197e0SAl Viro put_link(nd, &link, cookie); 1637bd92d7feSAl Viro } 1638bd92d7feSAl Viro } 1639ee0827cdSAl Viro 1640ee0827cdSAl Viro if (nd->flags & LOOKUP_RCU) { 16414455ca62SAl Viro /* went all way through without dropping RCU */ 1642bd92d7feSAl Viro BUG_ON(err); 1643086e183aSAl Viro if (nameidata_drop_rcu_last(nd)) 1644bd92d7feSAl Viro err = -ECHILD; 1645086e183aSAl Viro } 164631e6b01fSNick Piggin 1647bd23a539SAl Viro if (!err) { 1648bd92d7feSAl Viro err = handle_reval_path(nd); 1649bd23a539SAl Viro if (err) 1650bd23a539SAl Viro path_put(&nd->path); 1651bd23a539SAl Viro } 1652bd92d7feSAl Viro 1653bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1654bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1655bd92d7feSAl Viro path_put(&nd->path); 1656bd23a539SAl Viro err = -ENOTDIR; 1657bd92d7feSAl Viro } 1658bd92d7feSAl Viro } 165916c2cd71SAl Viro 166070e9b357SAl Viro if (base) 166170e9b357SAl Viro fput(base); 1662ee0827cdSAl Viro 16635b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 166431e6b01fSNick Piggin path_put(&nd->root); 166531e6b01fSNick Piggin nd->root.mnt = NULL; 166631e6b01fSNick Piggin } 1667bd92d7feSAl Viro return err; 166831e6b01fSNick Piggin } 166931e6b01fSNick Piggin 1670ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1671ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1672ee0827cdSAl Viro { 1673ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1674ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1675ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1676ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1677ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1678ee0827cdSAl Viro 167931e6b01fSNick Piggin if (likely(!retval)) { 168031e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 168131e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 168231e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 168331e6b01fSNick Piggin } 168431e6b01fSNick Piggin } 1685170aa3d0SUlrich Drepper return retval; 16861da177e4SLinus Torvalds } 16871da177e4SLinus Torvalds 1688c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16895590ff0dSUlrich Drepper { 1690c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16915590ff0dSUlrich Drepper } 16925590ff0dSUlrich Drepper 1693d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1694d1811465SAl Viro { 1695d1811465SAl Viro struct nameidata nd; 1696d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1697d1811465SAl Viro if (!res) 1698d1811465SAl Viro *path = nd.path; 1699d1811465SAl Viro return res; 1700d1811465SAl Viro } 1701d1811465SAl Viro 170216f18200SJosef 'Jeff' Sipek /** 170316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 170416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 170516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 170616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 170716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 170816f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 170916f18200SJosef 'Jeff' Sipek */ 171016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 171116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 171216f18200SJosef 'Jeff' Sipek struct nameidata *nd) 171316f18200SJosef 'Jeff' Sipek { 17145b6ca027SAl Viro nd->root.dentry = dentry; 17155b6ca027SAl Viro nd->root.mnt = mnt; 17165b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 17175b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 171816f18200SJosef 'Jeff' Sipek } 171916f18200SJosef 'Jeff' Sipek 1720eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1721eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 17221da177e4SLinus Torvalds { 172381fca444SChristoph Hellwig struct inode *inode = base->d_inode; 17241da177e4SLinus Torvalds struct dentry *dentry; 17251da177e4SLinus Torvalds int err; 17261da177e4SLinus Torvalds 1727b74c79e9SNick Piggin err = exec_permission(inode, 0); 172881fca444SChristoph Hellwig if (err) 172981fca444SChristoph Hellwig return ERR_PTR(err); 17301da177e4SLinus Torvalds 17311da177e4SLinus Torvalds /* 1732b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1733b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1734b04f784eSNick Piggin * a double lookup. 17356e6b1bd1SAl Viro */ 17366e6b1bd1SAl Viro dentry = d_lookup(base, name); 17376e6b1bd1SAl Viro 1738fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 17396e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 17406e6b1bd1SAl Viro 17411da177e4SLinus Torvalds if (!dentry) 1742baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17435a202bcdSAl Viro 17441da177e4SLinus Torvalds return dentry; 17451da177e4SLinus Torvalds } 17461da177e4SLinus Torvalds 1747057f6c01SJames Morris /* 1748057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1749057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1750057f6c01SJames Morris * SMP-safe. 1751057f6c01SJames Morris */ 1752a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17531da177e4SLinus Torvalds { 17544ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17551da177e4SLinus Torvalds } 17561da177e4SLinus Torvalds 1757eead1911SChristoph Hellwig /** 1758a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1759eead1911SChristoph Hellwig * @name: pathname component to lookup 1760eead1911SChristoph Hellwig * @base: base directory to lookup from 1761eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1762eead1911SChristoph Hellwig * 1763a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1764a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1765eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1766eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1767eead1911SChristoph Hellwig */ 1768057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1769057f6c01SJames Morris { 1770057f6c01SJames Morris struct qstr this; 17716a96ba54SAl Viro unsigned long hash; 17726a96ba54SAl Viro unsigned int c; 1773057f6c01SJames Morris 17742f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17752f9092e1SDavid Woodhouse 17766a96ba54SAl Viro this.name = name; 17776a96ba54SAl Viro this.len = len; 17786a96ba54SAl Viro if (!len) 17796a96ba54SAl Viro return ERR_PTR(-EACCES); 17806a96ba54SAl Viro 17816a96ba54SAl Viro hash = init_name_hash(); 17826a96ba54SAl Viro while (len--) { 17836a96ba54SAl Viro c = *(const unsigned char *)name++; 17846a96ba54SAl Viro if (c == '/' || c == '\0') 17856a96ba54SAl Viro return ERR_PTR(-EACCES); 17866a96ba54SAl Viro hash = partial_name_hash(c, hash); 17876a96ba54SAl Viro } 17886a96ba54SAl Viro this.hash = end_name_hash(hash); 17895a202bcdSAl Viro /* 17905a202bcdSAl Viro * See if the low-level filesystem might want 17915a202bcdSAl Viro * to use its own hash.. 17925a202bcdSAl Viro */ 17935a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17945a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17955a202bcdSAl Viro if (err < 0) 17965a202bcdSAl Viro return ERR_PTR(err); 17975a202bcdSAl Viro } 1798eead1911SChristoph Hellwig 179949705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1800057f6c01SJames Morris } 1801057f6c01SJames Morris 18022d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 18032d8f3038SAl Viro struct path *path) 18041da177e4SLinus Torvalds { 18052d8f3038SAl Viro struct nameidata nd; 1806f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 18071da177e4SLinus Torvalds int err = PTR_ERR(tmp); 18081da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 18092d8f3038SAl Viro 18102d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18112d8f3038SAl Viro 18122d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 18131da177e4SLinus Torvalds putname(tmp); 18142d8f3038SAl Viro if (!err) 18152d8f3038SAl Viro *path = nd.path; 18161da177e4SLinus Torvalds } 18171da177e4SLinus Torvalds return err; 18181da177e4SLinus Torvalds } 18191da177e4SLinus Torvalds 18202ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 18212ad94ae6SAl Viro struct nameidata *nd, char **name) 18222ad94ae6SAl Viro { 18232ad94ae6SAl Viro char *s = getname(path); 18242ad94ae6SAl Viro int error; 18252ad94ae6SAl Viro 18262ad94ae6SAl Viro if (IS_ERR(s)) 18272ad94ae6SAl Viro return PTR_ERR(s); 18282ad94ae6SAl Viro 18292ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 18302ad94ae6SAl Viro if (error) 18312ad94ae6SAl Viro putname(s); 18322ad94ae6SAl Viro else 18332ad94ae6SAl Viro *name = s; 18342ad94ae6SAl Viro 18352ad94ae6SAl Viro return error; 18362ad94ae6SAl Viro } 18372ad94ae6SAl Viro 18381da177e4SLinus Torvalds /* 18391da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18401da177e4SLinus Torvalds * minimal. 18411da177e4SLinus Torvalds */ 18421da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18431da177e4SLinus Torvalds { 1844da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1845da9592edSDavid Howells 18461da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18471da177e4SLinus Torvalds return 0; 1848da9592edSDavid Howells if (inode->i_uid == fsuid) 18491da177e4SLinus Torvalds return 0; 1850da9592edSDavid Howells if (dir->i_uid == fsuid) 18511da177e4SLinus Torvalds return 0; 18521da177e4SLinus Torvalds return !capable(CAP_FOWNER); 18531da177e4SLinus Torvalds } 18541da177e4SLinus Torvalds 18551da177e4SLinus Torvalds /* 18561da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18571da177e4SLinus Torvalds * whether the type of victim is right. 18581da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18591da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18601da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18611da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18621da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18631da177e4SLinus Torvalds * a. be owner of dir, or 18641da177e4SLinus Torvalds * b. be owner of victim, or 18651da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18661da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18671da177e4SLinus Torvalds * links pointing to it. 18681da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18691da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18701da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18711da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18721da177e4SLinus Torvalds * nfs_async_unlink(). 18731da177e4SLinus Torvalds */ 1874858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18751da177e4SLinus Torvalds { 18761da177e4SLinus Torvalds int error; 18771da177e4SLinus Torvalds 18781da177e4SLinus Torvalds if (!victim->d_inode) 18791da177e4SLinus Torvalds return -ENOENT; 18801da177e4SLinus Torvalds 18811da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1882cccc6bbaSAl Viro audit_inode_child(victim, dir); 18831da177e4SLinus Torvalds 1884f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18851da177e4SLinus Torvalds if (error) 18861da177e4SLinus Torvalds return error; 18871da177e4SLinus Torvalds if (IS_APPEND(dir)) 18881da177e4SLinus Torvalds return -EPERM; 18891da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1890f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18911da177e4SLinus Torvalds return -EPERM; 18921da177e4SLinus Torvalds if (isdir) { 18931da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18941da177e4SLinus Torvalds return -ENOTDIR; 18951da177e4SLinus Torvalds if (IS_ROOT(victim)) 18961da177e4SLinus Torvalds return -EBUSY; 18971da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18981da177e4SLinus Torvalds return -EISDIR; 18991da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19001da177e4SLinus Torvalds return -ENOENT; 19011da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 19021da177e4SLinus Torvalds return -EBUSY; 19031da177e4SLinus Torvalds return 0; 19041da177e4SLinus Torvalds } 19051da177e4SLinus Torvalds 19061da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 19071da177e4SLinus Torvalds * dir. 19081da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 19091da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 19101da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 19111da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 19121da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 19131da177e4SLinus Torvalds */ 1914a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 19151da177e4SLinus Torvalds { 19161da177e4SLinus Torvalds if (child->d_inode) 19171da177e4SLinus Torvalds return -EEXIST; 19181da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19191da177e4SLinus Torvalds return -ENOENT; 1920f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 19211da177e4SLinus Torvalds } 19221da177e4SLinus Torvalds 19231da177e4SLinus Torvalds /* 19241da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 19251da177e4SLinus Torvalds */ 19261da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 19271da177e4SLinus Torvalds { 19281da177e4SLinus Torvalds struct dentry *p; 19291da177e4SLinus Torvalds 19301da177e4SLinus Torvalds if (p1 == p2) { 1931f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 19321da177e4SLinus Torvalds return NULL; 19331da177e4SLinus Torvalds } 19341da177e4SLinus Torvalds 1935a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19361da177e4SLinus Torvalds 1937e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1938e2761a11SOGAWA Hirofumi if (p) { 1939f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1940f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19411da177e4SLinus Torvalds return p; 19421da177e4SLinus Torvalds } 19431da177e4SLinus Torvalds 1944e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1945e2761a11SOGAWA Hirofumi if (p) { 1946f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1947f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19481da177e4SLinus Torvalds return p; 19491da177e4SLinus Torvalds } 19501da177e4SLinus Torvalds 1951f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1952f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19531da177e4SLinus Torvalds return NULL; 19541da177e4SLinus Torvalds } 19551da177e4SLinus Torvalds 19561da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19571da177e4SLinus Torvalds { 19581b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19591da177e4SLinus Torvalds if (p1 != p2) { 19601b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1961a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19621da177e4SLinus Torvalds } 19631da177e4SLinus Torvalds } 19641da177e4SLinus Torvalds 19651da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19661da177e4SLinus Torvalds struct nameidata *nd) 19671da177e4SLinus Torvalds { 1968a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19691da177e4SLinus Torvalds 19701da177e4SLinus Torvalds if (error) 19711da177e4SLinus Torvalds return error; 19721da177e4SLinus Torvalds 1973acfa4380SAl Viro if (!dir->i_op->create) 19741da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19751da177e4SLinus Torvalds mode &= S_IALLUGO; 19761da177e4SLinus Torvalds mode |= S_IFREG; 19771da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19781da177e4SLinus Torvalds if (error) 19791da177e4SLinus Torvalds return error; 19801da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1981a74574aaSStephen Smalley if (!error) 1982f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19831da177e4SLinus Torvalds return error; 19841da177e4SLinus Torvalds } 19851da177e4SLinus Torvalds 198673d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19871da177e4SLinus Torvalds { 19883fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19891da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19901da177e4SLinus Torvalds int error; 19911da177e4SLinus Torvalds 1992bcda7652SAl Viro /* O_PATH? */ 1993bcda7652SAl Viro if (!acc_mode) 1994bcda7652SAl Viro return 0; 1995bcda7652SAl Viro 19961da177e4SLinus Torvalds if (!inode) 19971da177e4SLinus Torvalds return -ENOENT; 19981da177e4SLinus Torvalds 1999c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2000c8fe8f30SChristoph Hellwig case S_IFLNK: 20011da177e4SLinus Torvalds return -ELOOP; 2002c8fe8f30SChristoph Hellwig case S_IFDIR: 2003c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 20041da177e4SLinus Torvalds return -EISDIR; 2005c8fe8f30SChristoph Hellwig break; 2006c8fe8f30SChristoph Hellwig case S_IFBLK: 2007c8fe8f30SChristoph Hellwig case S_IFCHR: 20083fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 20091da177e4SLinus Torvalds return -EACCES; 2010c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2011c8fe8f30SChristoph Hellwig case S_IFIFO: 2012c8fe8f30SChristoph Hellwig case S_IFSOCK: 20131da177e4SLinus Torvalds flag &= ~O_TRUNC; 2014c8fe8f30SChristoph Hellwig break; 20154a3fd211SDave Hansen } 2016b41572e9SDave Hansen 20173fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2018b41572e9SDave Hansen if (error) 2019b41572e9SDave Hansen return error; 20206146f0d5SMimi Zohar 20211da177e4SLinus Torvalds /* 20221da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 20231da177e4SLinus Torvalds */ 20241da177e4SLinus Torvalds if (IS_APPEND(inode)) { 20258737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 20267715b521SAl Viro return -EPERM; 20271da177e4SLinus Torvalds if (flag & O_TRUNC) 20287715b521SAl Viro return -EPERM; 20291da177e4SLinus Torvalds } 20301da177e4SLinus Torvalds 20311da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 20327715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 20337715b521SAl Viro return -EPERM; 20341da177e4SLinus Torvalds 20351da177e4SLinus Torvalds /* 20361da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 20371da177e4SLinus Torvalds */ 2038b65a9cfcSAl Viro return break_lease(inode, flag); 20397715b521SAl Viro } 20407715b521SAl Viro 2041e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20427715b521SAl Viro { 2043e1181ee6SJeff Layton struct path *path = &filp->f_path; 20447715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20457715b521SAl Viro int error = get_write_access(inode); 20461da177e4SLinus Torvalds if (error) 20477715b521SAl Viro return error; 20481da177e4SLinus Torvalds /* 20491da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20501da177e4SLinus Torvalds */ 20511da177e4SLinus Torvalds error = locks_verify_locked(inode); 2052be6d3e56SKentaro Takeda if (!error) 2053ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20541da177e4SLinus Torvalds if (!error) { 20557715b521SAl Viro error = do_truncate(path->dentry, 0, 2056d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2057e1181ee6SJeff Layton filp); 20581da177e4SLinus Torvalds } 20591da177e4SLinus Torvalds put_write_access(inode); 2060acd0c935SMimi Zohar return error; 20611da177e4SLinus Torvalds } 20621da177e4SLinus Torvalds 2063d57999e1SDave Hansen /* 2064d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2065d57999e1SDave Hansen * 00 - read-only 2066d57999e1SDave Hansen * 01 - write-only 2067d57999e1SDave Hansen * 10 - read-write 2068d57999e1SDave Hansen * 11 - special 2069d57999e1SDave Hansen * it is changed into 2070d57999e1SDave Hansen * 00 - no permissions needed 2071d57999e1SDave Hansen * 01 - read-permission 2072d57999e1SDave Hansen * 10 - write-permission 2073d57999e1SDave Hansen * 11 - read-write 2074d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2075d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2076d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2077d57999e1SDave Hansen * later). 2078d57999e1SDave Hansen * 2079d57999e1SDave Hansen */ 2080d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2081d57999e1SDave Hansen { 2082d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2083d57999e1SDave Hansen flag++; 2084d57999e1SDave Hansen return flag; 2085d57999e1SDave Hansen } 2086d57999e1SDave Hansen 208731e6b01fSNick Piggin /* 2088fe2d35ffSAl Viro * Handle the last step of open() 208931e6b01fSNick Piggin */ 2090fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2091c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2092fb1cc555SAl Viro { 2093a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20946c0d46c4SAl Viro struct dentry *dentry; 2095ca344a89SAl Viro int open_flag = op->open_flag; 20966c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2097ca344a89SAl Viro int want_write = 0; 2098bcda7652SAl Viro int acc_mode = op->acc_mode; 2099fb1cc555SAl Viro struct file *filp; 210016c2cd71SAl Viro int error; 2101fb1cc555SAl Viro 2102c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2103c3e380b0SAl Viro nd->flags |= op->intent; 2104c3e380b0SAl Viro 21051f36f774SAl Viro switch (nd->last_type) { 21061f36f774SAl Viro case LAST_DOTDOT: 2107176306f5SNeil Brown case LAST_DOT: 2108fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2109fe2d35ffSAl Viro if (error) 2110fe2d35ffSAl Viro return ERR_PTR(error); 21111f36f774SAl Viro /* fallthrough */ 21121f36f774SAl Viro case LAST_ROOT: 2113fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2114fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2115fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2116fe2d35ffSAl Viro } 211716c2cd71SAl Viro error = handle_reval_path(nd); 211816c2cd71SAl Viro if (error) 211916c2cd71SAl Viro goto exit; 2120fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2121ca344a89SAl Viro if (open_flag & O_CREAT) { 212216c2cd71SAl Viro error = -EISDIR; 21231f36f774SAl Viro goto exit; 2124fe2d35ffSAl Viro } 2125fe2d35ffSAl Viro goto ok; 21261f36f774SAl Viro case LAST_BIND: 2127fe2d35ffSAl Viro /* can't be RCU mode here */ 212816c2cd71SAl Viro error = handle_reval_path(nd); 212916c2cd71SAl Viro if (error) 213016c2cd71SAl Viro goto exit; 21311f36f774SAl Viro audit_inode(pathname, dir); 21321f36f774SAl Viro goto ok; 21331f36f774SAl Viro } 2134a2c36b45SAl Viro 2135ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2136bcda7652SAl Viro int symlink_ok = 0; 2137fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2138fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2139bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2140bcda7652SAl Viro symlink_ok = 1; 2141fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2142ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2143ce57dfc1SAl Viro !symlink_ok); 2144ce57dfc1SAl Viro if (error < 0) 2145fe2d35ffSAl Viro return ERR_PTR(error); 2146ce57dfc1SAl Viro if (error) /* symlink */ 2147fe2d35ffSAl Viro return NULL; 2148fe2d35ffSAl Viro /* sayonara */ 2149fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2150fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2151fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2152fe2d35ffSAl Viro } 2153fe2d35ffSAl Viro 2154fe2d35ffSAl Viro error = -ENOTDIR; 2155fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2156ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2157fe2d35ffSAl Viro goto exit; 2158fe2d35ffSAl Viro } 2159fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2160fe2d35ffSAl Viro goto ok; 2161fe2d35ffSAl Viro } 2162fe2d35ffSAl Viro 2163fe2d35ffSAl Viro /* create side of things */ 2164fe2d35ffSAl Viro 2165fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2166fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2167fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2168fe2d35ffSAl Viro } 2169fe2d35ffSAl Viro 2170fe2d35ffSAl Viro audit_inode(pathname, dir); 217116c2cd71SAl Viro error = -EISDIR; 21721f36f774SAl Viro /* trailing slashes? */ 217331e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21741f36f774SAl Viro goto exit; 21751f36f774SAl Viro 2176a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2177a1e28038SAl Viro 21786c0d46c4SAl Viro dentry = lookup_hash(nd); 21796c0d46c4SAl Viro error = PTR_ERR(dentry); 21806c0d46c4SAl Viro if (IS_ERR(dentry)) { 2181fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2182fb1cc555SAl Viro goto exit; 2183fb1cc555SAl Viro } 2184fb1cc555SAl Viro 21856c0d46c4SAl Viro path->dentry = dentry; 21866c0d46c4SAl Viro path->mnt = nd->path.mnt; 21876c0d46c4SAl Viro 2188fb1cc555SAl Viro /* Negative dentry, just create the file */ 21896c0d46c4SAl Viro if (!dentry->d_inode) { 21906c0d46c4SAl Viro int mode = op->mode; 21916c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21926c0d46c4SAl Viro mode &= ~current_umask(); 2193fb1cc555SAl Viro /* 2194fb1cc555SAl Viro * This write is needed to ensure that a 21956c0d46c4SAl Viro * rw->ro transition does not occur between 2196fb1cc555SAl Viro * the time when the file is created and when 2197fb1cc555SAl Viro * a permanent write count is taken through 2198fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2199fb1cc555SAl Viro */ 2200fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2201fb1cc555SAl Viro if (error) 2202fb1cc555SAl Viro goto exit_mutex_unlock; 2203ca344a89SAl Viro want_write = 1; 22049b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2205ca344a89SAl Viro open_flag &= ~O_TRUNC; 22066c0d46c4SAl Viro will_truncate = 0; 2207bcda7652SAl Viro acc_mode = MAY_OPEN; 22086c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 22096c0d46c4SAl Viro if (error) 22106c0d46c4SAl Viro goto exit_mutex_unlock; 22116c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 22126c0d46c4SAl Viro if (error) 22136c0d46c4SAl Viro goto exit_mutex_unlock; 22146c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 22156c0d46c4SAl Viro dput(nd->path.dentry); 22166c0d46c4SAl Viro nd->path.dentry = dentry; 2217ca344a89SAl Viro goto common; 2218fb1cc555SAl Viro } 2219fb1cc555SAl Viro 2220fb1cc555SAl Viro /* 2221fb1cc555SAl Viro * It already exists. 2222fb1cc555SAl Viro */ 2223fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2224fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2225fb1cc555SAl Viro 2226fb1cc555SAl Viro error = -EEXIST; 2227ca344a89SAl Viro if (open_flag & O_EXCL) 2228fb1cc555SAl Viro goto exit_dput; 2229fb1cc555SAl Viro 22309875cf80SDavid Howells error = follow_managed(path, nd->flags); 22319875cf80SDavid Howells if (error < 0) 2232fb1cc555SAl Viro goto exit_dput; 2233fb1cc555SAl Viro 2234fb1cc555SAl Viro error = -ENOENT; 2235fb1cc555SAl Viro if (!path->dentry->d_inode) 2236fb1cc555SAl Viro goto exit_dput; 22379e67f361SAl Viro 22389e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2239fb1cc555SAl Viro return NULL; 2240fb1cc555SAl Viro 2241fb1cc555SAl Viro path_to_nameidata(path, nd); 224231e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2243fb1cc555SAl Viro error = -EISDIR; 224431e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2245fb1cc555SAl Viro goto exit; 224667ee3ad2SAl Viro ok: 22476c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22486c0d46c4SAl Viro will_truncate = 0; 22496c0d46c4SAl Viro 22500f9d1a10SAl Viro if (will_truncate) { 22510f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22520f9d1a10SAl Viro if (error) 22530f9d1a10SAl Viro goto exit; 2254ca344a89SAl Viro want_write = 1; 22550f9d1a10SAl Viro } 2256ca344a89SAl Viro common: 2257bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2258ca344a89SAl Viro if (error) 22590f9d1a10SAl Viro goto exit; 22600f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22610f9d1a10SAl Viro if (!IS_ERR(filp)) { 22620f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22630f9d1a10SAl Viro if (error) { 22640f9d1a10SAl Viro fput(filp); 22650f9d1a10SAl Viro filp = ERR_PTR(error); 22660f9d1a10SAl Viro } 22670f9d1a10SAl Viro } 22680f9d1a10SAl Viro if (!IS_ERR(filp)) { 22690f9d1a10SAl Viro if (will_truncate) { 22700f9d1a10SAl Viro error = handle_truncate(filp); 22710f9d1a10SAl Viro if (error) { 22720f9d1a10SAl Viro fput(filp); 22730f9d1a10SAl Viro filp = ERR_PTR(error); 22740f9d1a10SAl Viro } 22750f9d1a10SAl Viro } 22760f9d1a10SAl Viro } 2277ca344a89SAl Viro out: 2278ca344a89SAl Viro if (want_write) 22790f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22800f9d1a10SAl Viro path_put(&nd->path); 2281fb1cc555SAl Viro return filp; 2282fb1cc555SAl Viro 2283fb1cc555SAl Viro exit_mutex_unlock: 2284fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2285fb1cc555SAl Viro exit_dput: 2286fb1cc555SAl Viro path_put_conditional(path, nd); 2287fb1cc555SAl Viro exit: 2288ca344a89SAl Viro filp = ERR_PTR(error); 2289ca344a89SAl Viro goto out; 2290fb1cc555SAl Viro } 2291fb1cc555SAl Viro 229213aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 229373d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22941da177e4SLinus Torvalds { 2295fe2d35ffSAl Viro struct file *base = NULL; 22964a3fd211SDave Hansen struct file *filp; 22979850c056SAl Viro struct path path; 229813aab428SAl Viro int error; 229931e6b01fSNick Piggin 230031e6b01fSNick Piggin filp = get_empty_filp(); 230131e6b01fSNick Piggin if (!filp) 230231e6b01fSNick Piggin return ERR_PTR(-ENFILE); 230331e6b01fSNick Piggin 230447c805dcSAl Viro filp->f_flags = op->open_flag; 230573d049a4SAl Viro nd->intent.open.file = filp; 230673d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 230773d049a4SAl Viro nd->intent.open.create_mode = op->mode; 230831e6b01fSNick Piggin 230973d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 231031e6b01fSNick Piggin if (unlikely(error)) 231113aab428SAl Viro goto out_filp; 231231e6b01fSNick Piggin 2313fe2d35ffSAl Viro current->total_link_count = 0; 231473d049a4SAl Viro error = link_path_walk(pathname, nd); 231531e6b01fSNick Piggin if (unlikely(error)) 231631e6b01fSNick Piggin goto out_filp; 23171da177e4SLinus Torvalds 231873d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2319806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 23207b9337aaSNick Piggin struct path link = path; 2321def4af30SAl Viro void *cookie; 2322574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 232373d049a4SAl Viro path_put_conditional(&path, nd); 232473d049a4SAl Viro path_put(&nd->path); 232540b39136SAl Viro filp = ERR_PTR(-ELOOP); 232640b39136SAl Viro break; 232740b39136SAl Viro } 232873d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 232973d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2330574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2331c3e380b0SAl Viro if (unlikely(error)) 2332f1afe9efSAl Viro filp = ERR_PTR(error); 2333c3e380b0SAl Viro else 233473d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2335574197e0SAl Viro put_link(nd, &link, cookie); 2336806b681cSAl Viro } 233710fa8e62SAl Viro out: 233873d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 233973d049a4SAl Viro path_put(&nd->root); 2340fe2d35ffSAl Viro if (base) 2341fe2d35ffSAl Viro fput(base); 234273d049a4SAl Viro release_open_intent(nd); 234310fa8e62SAl Viro return filp; 23441da177e4SLinus Torvalds 234531e6b01fSNick Piggin out_filp: 234610fa8e62SAl Viro filp = ERR_PTR(error); 234710fa8e62SAl Viro goto out; 2348de459215SKirill Korotaev } 23491da177e4SLinus Torvalds 235013aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 235113aab428SAl Viro const struct open_flags *op, int flags) 235213aab428SAl Viro { 235373d049a4SAl Viro struct nameidata nd; 235413aab428SAl Viro struct file *filp; 235513aab428SAl Viro 235673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 235713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 235873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 235913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 236073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 236113aab428SAl Viro return filp; 236213aab428SAl Viro } 236313aab428SAl Viro 236473d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 236573d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 236673d049a4SAl Viro { 236773d049a4SAl Viro struct nameidata nd; 236873d049a4SAl Viro struct file *file; 236973d049a4SAl Viro 237073d049a4SAl Viro nd.root.mnt = mnt; 237173d049a4SAl Viro nd.root.dentry = dentry; 237273d049a4SAl Viro 237373d049a4SAl Viro flags |= LOOKUP_ROOT; 237473d049a4SAl Viro 2375bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 237673d049a4SAl Viro return ERR_PTR(-ELOOP); 237773d049a4SAl Viro 237873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 237973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 238073d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 238173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 238273d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 238373d049a4SAl Viro return file; 238473d049a4SAl Viro } 238573d049a4SAl Viro 23861da177e4SLinus Torvalds /** 23871da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23881da177e4SLinus Torvalds * @nd: nameidata info 23891da177e4SLinus Torvalds * @is_dir: directory flag 23901da177e4SLinus Torvalds * 23911da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23921da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2393c663e5d8SChristoph Hellwig * 23944ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23951da177e4SLinus Torvalds */ 23961da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23971da177e4SLinus Torvalds { 2398c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23991da177e4SLinus Torvalds 24004ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2401c663e5d8SChristoph Hellwig /* 2402c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2403c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2404c663e5d8SChristoph Hellwig */ 24051da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 24061da177e4SLinus Torvalds goto fail; 24071da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 24083516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2409a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2410c663e5d8SChristoph Hellwig 2411c663e5d8SChristoph Hellwig /* 2412c663e5d8SChristoph Hellwig * Do the final lookup. 2413c663e5d8SChristoph Hellwig */ 241449705b77SChristoph Hellwig dentry = lookup_hash(nd); 24151da177e4SLinus Torvalds if (IS_ERR(dentry)) 24161da177e4SLinus Torvalds goto fail; 2417c663e5d8SChristoph Hellwig 2418e9baf6e5SAl Viro if (dentry->d_inode) 2419e9baf6e5SAl Viro goto eexist; 2420c663e5d8SChristoph Hellwig /* 2421c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2422c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2423c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2424c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2425c663e5d8SChristoph Hellwig */ 2426e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 24271da177e4SLinus Torvalds dput(dentry); 24281da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2429e9baf6e5SAl Viro } 2430e9baf6e5SAl Viro return dentry; 2431e9baf6e5SAl Viro eexist: 2432e9baf6e5SAl Viro dput(dentry); 2433e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 24341da177e4SLinus Torvalds fail: 24351da177e4SLinus Torvalds return dentry; 24361da177e4SLinus Torvalds } 2437f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 24381da177e4SLinus Torvalds 24391da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24401da177e4SLinus Torvalds { 2441a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24421da177e4SLinus Torvalds 24431da177e4SLinus Torvalds if (error) 24441da177e4SLinus Torvalds return error; 24451da177e4SLinus Torvalds 24461da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 24471da177e4SLinus Torvalds return -EPERM; 24481da177e4SLinus Torvalds 2449acfa4380SAl Viro if (!dir->i_op->mknod) 24501da177e4SLinus Torvalds return -EPERM; 24511da177e4SLinus Torvalds 245208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 245308ce5f16SSerge E. Hallyn if (error) 245408ce5f16SSerge E. Hallyn return error; 245508ce5f16SSerge E. Hallyn 24561da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24571da177e4SLinus Torvalds if (error) 24581da177e4SLinus Torvalds return error; 24591da177e4SLinus Torvalds 24601da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2461a74574aaSStephen Smalley if (!error) 2462f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24631da177e4SLinus Torvalds return error; 24641da177e4SLinus Torvalds } 24651da177e4SLinus Torvalds 2466463c3197SDave Hansen static int may_mknod(mode_t mode) 2467463c3197SDave Hansen { 2468463c3197SDave Hansen switch (mode & S_IFMT) { 2469463c3197SDave Hansen case S_IFREG: 2470463c3197SDave Hansen case S_IFCHR: 2471463c3197SDave Hansen case S_IFBLK: 2472463c3197SDave Hansen case S_IFIFO: 2473463c3197SDave Hansen case S_IFSOCK: 2474463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2475463c3197SDave Hansen return 0; 2476463c3197SDave Hansen case S_IFDIR: 2477463c3197SDave Hansen return -EPERM; 2478463c3197SDave Hansen default: 2479463c3197SDave Hansen return -EINVAL; 2480463c3197SDave Hansen } 2481463c3197SDave Hansen } 2482463c3197SDave Hansen 24832e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24842e4d0924SHeiko Carstens unsigned, dev) 24851da177e4SLinus Torvalds { 24862ad94ae6SAl Viro int error; 24871da177e4SLinus Torvalds char *tmp; 24881da177e4SLinus Torvalds struct dentry *dentry; 24891da177e4SLinus Torvalds struct nameidata nd; 24901da177e4SLinus Torvalds 24911da177e4SLinus Torvalds if (S_ISDIR(mode)) 24921da177e4SLinus Torvalds return -EPERM; 24931da177e4SLinus Torvalds 24942ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24951da177e4SLinus Torvalds if (error) 24962ad94ae6SAl Viro return error; 24972ad94ae6SAl Viro 24981da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2499463c3197SDave Hansen if (IS_ERR(dentry)) { 25001da177e4SLinus Torvalds error = PTR_ERR(dentry); 2501463c3197SDave Hansen goto out_unlock; 2502463c3197SDave Hansen } 25034ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2504ce3b0f8dSAl Viro mode &= ~current_umask(); 2505463c3197SDave Hansen error = may_mknod(mode); 2506463c3197SDave Hansen if (error) 2507463c3197SDave Hansen goto out_dput; 2508463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2509463c3197SDave Hansen if (error) 2510463c3197SDave Hansen goto out_dput; 2511be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2512be6d3e56SKentaro Takeda if (error) 2513be6d3e56SKentaro Takeda goto out_drop_write; 25141da177e4SLinus Torvalds switch (mode & S_IFMT) { 25151da177e4SLinus Torvalds case 0: case S_IFREG: 25164ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 25171da177e4SLinus Torvalds break; 25181da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 25194ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 25201da177e4SLinus Torvalds new_decode_dev(dev)); 25211da177e4SLinus Torvalds break; 25221da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 25234ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 25241da177e4SLinus Torvalds break; 25251da177e4SLinus Torvalds } 2526be6d3e56SKentaro Takeda out_drop_write: 2527463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2528463c3197SDave Hansen out_dput: 25291da177e4SLinus Torvalds dput(dentry); 2530463c3197SDave Hansen out_unlock: 25314ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25321d957f9bSJan Blunck path_put(&nd.path); 25331da177e4SLinus Torvalds putname(tmp); 25341da177e4SLinus Torvalds 25351da177e4SLinus Torvalds return error; 25361da177e4SLinus Torvalds } 25371da177e4SLinus Torvalds 25383480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25395590ff0dSUlrich Drepper { 25405590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25415590ff0dSUlrich Drepper } 25425590ff0dSUlrich Drepper 25431da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25441da177e4SLinus Torvalds { 2545a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25461da177e4SLinus Torvalds 25471da177e4SLinus Torvalds if (error) 25481da177e4SLinus Torvalds return error; 25491da177e4SLinus Torvalds 2550acfa4380SAl Viro if (!dir->i_op->mkdir) 25511da177e4SLinus Torvalds return -EPERM; 25521da177e4SLinus Torvalds 25531da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25541da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25551da177e4SLinus Torvalds if (error) 25561da177e4SLinus Torvalds return error; 25571da177e4SLinus Torvalds 25581da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2559a74574aaSStephen Smalley if (!error) 2560f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25611da177e4SLinus Torvalds return error; 25621da177e4SLinus Torvalds } 25631da177e4SLinus Torvalds 25642e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25651da177e4SLinus Torvalds { 25661da177e4SLinus Torvalds int error = 0; 25671da177e4SLinus Torvalds char * tmp; 25686902d925SDave Hansen struct dentry *dentry; 25696902d925SDave Hansen struct nameidata nd; 25701da177e4SLinus Torvalds 25712ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25722ad94ae6SAl Viro if (error) 25736902d925SDave Hansen goto out_err; 25741da177e4SLinus Torvalds 25751da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25761da177e4SLinus Torvalds error = PTR_ERR(dentry); 25776902d925SDave Hansen if (IS_ERR(dentry)) 25786902d925SDave Hansen goto out_unlock; 25796902d925SDave Hansen 25804ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2581ce3b0f8dSAl Viro mode &= ~current_umask(); 2582463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2583463c3197SDave Hansen if (error) 2584463c3197SDave Hansen goto out_dput; 2585be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2586be6d3e56SKentaro Takeda if (error) 2587be6d3e56SKentaro Takeda goto out_drop_write; 25884ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2589be6d3e56SKentaro Takeda out_drop_write: 2590463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2591463c3197SDave Hansen out_dput: 25921da177e4SLinus Torvalds dput(dentry); 25936902d925SDave Hansen out_unlock: 25944ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25951d957f9bSJan Blunck path_put(&nd.path); 25961da177e4SLinus Torvalds putname(tmp); 25976902d925SDave Hansen out_err: 25981da177e4SLinus Torvalds return error; 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds 26013cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 26025590ff0dSUlrich Drepper { 26035590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 26045590ff0dSUlrich Drepper } 26055590ff0dSUlrich Drepper 26061da177e4SLinus Torvalds /* 26071da177e4SLinus Torvalds * We try to drop the dentry early: we should have 26081da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 26091da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 26101da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 26111da177e4SLinus Torvalds * 26121da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 26131da177e4SLinus Torvalds * do a 26141da177e4SLinus Torvalds * 26151da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 26161da177e4SLinus Torvalds * return -EBUSY; 26171da177e4SLinus Torvalds * 26181da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 26191da177e4SLinus Torvalds * that is still in use by something else.. 26201da177e4SLinus Torvalds */ 26211da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 26221da177e4SLinus Torvalds { 26231da177e4SLinus Torvalds dget(dentry); 26241da177e4SLinus Torvalds shrink_dcache_parent(dentry); 26251da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2626b7ab39f6SNick Piggin if (dentry->d_count == 2) 26271da177e4SLinus Torvalds __d_drop(dentry); 26281da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 26291da177e4SLinus Torvalds } 26301da177e4SLinus Torvalds 26311da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 26321da177e4SLinus Torvalds { 26331da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26341da177e4SLinus Torvalds 26351da177e4SLinus Torvalds if (error) 26361da177e4SLinus Torvalds return error; 26371da177e4SLinus Torvalds 2638acfa4380SAl Viro if (!dir->i_op->rmdir) 26391da177e4SLinus Torvalds return -EPERM; 26401da177e4SLinus Torvalds 26411b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26421da177e4SLinus Torvalds dentry_unhash(dentry); 26431da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26441da177e4SLinus Torvalds error = -EBUSY; 26451da177e4SLinus Torvalds else { 26461da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 26471da177e4SLinus Torvalds if (!error) { 26481da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2649d83c49f3SAl Viro if (!error) { 26501da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2651d83c49f3SAl Viro dont_mount(dentry); 2652d83c49f3SAl Viro } 26531da177e4SLinus Torvalds } 26541da177e4SLinus Torvalds } 26551b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26561da177e4SLinus Torvalds if (!error) { 26571da177e4SLinus Torvalds d_delete(dentry); 26581da177e4SLinus Torvalds } 26591da177e4SLinus Torvalds dput(dentry); 26601da177e4SLinus Torvalds 26611da177e4SLinus Torvalds return error; 26621da177e4SLinus Torvalds } 26631da177e4SLinus Torvalds 26645590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26651da177e4SLinus Torvalds { 26661da177e4SLinus Torvalds int error = 0; 26671da177e4SLinus Torvalds char * name; 26681da177e4SLinus Torvalds struct dentry *dentry; 26691da177e4SLinus Torvalds struct nameidata nd; 26701da177e4SLinus Torvalds 26712ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26721da177e4SLinus Torvalds if (error) 26732ad94ae6SAl Viro return error; 26741da177e4SLinus Torvalds 26751da177e4SLinus Torvalds switch(nd.last_type) { 26761da177e4SLinus Torvalds case LAST_DOTDOT: 26771da177e4SLinus Torvalds error = -ENOTEMPTY; 26781da177e4SLinus Torvalds goto exit1; 26791da177e4SLinus Torvalds case LAST_DOT: 26801da177e4SLinus Torvalds error = -EINVAL; 26811da177e4SLinus Torvalds goto exit1; 26821da177e4SLinus Torvalds case LAST_ROOT: 26831da177e4SLinus Torvalds error = -EBUSY; 26841da177e4SLinus Torvalds goto exit1; 26851da177e4SLinus Torvalds } 26860612d9fbSOGAWA Hirofumi 26870612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26880612d9fbSOGAWA Hirofumi 26894ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 269049705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26911da177e4SLinus Torvalds error = PTR_ERR(dentry); 26926902d925SDave Hansen if (IS_ERR(dentry)) 26936902d925SDave Hansen goto exit2; 26940622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26950622753bSDave Hansen if (error) 26960622753bSDave Hansen goto exit3; 2697be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2698be6d3e56SKentaro Takeda if (error) 2699be6d3e56SKentaro Takeda goto exit4; 27004ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2701be6d3e56SKentaro Takeda exit4: 27020622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27030622753bSDave Hansen exit3: 27041da177e4SLinus Torvalds dput(dentry); 27056902d925SDave Hansen exit2: 27064ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27071da177e4SLinus Torvalds exit1: 27081d957f9bSJan Blunck path_put(&nd.path); 27091da177e4SLinus Torvalds putname(name); 27101da177e4SLinus Torvalds return error; 27111da177e4SLinus Torvalds } 27121da177e4SLinus Torvalds 27133cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 27145590ff0dSUlrich Drepper { 27155590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 27165590ff0dSUlrich Drepper } 27175590ff0dSUlrich Drepper 27181da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 27191da177e4SLinus Torvalds { 27201da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds if (error) 27231da177e4SLinus Torvalds return error; 27241da177e4SLinus Torvalds 2725acfa4380SAl Viro if (!dir->i_op->unlink) 27261da177e4SLinus Torvalds return -EPERM; 27271da177e4SLinus Torvalds 27281b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 27291da177e4SLinus Torvalds if (d_mountpoint(dentry)) 27301da177e4SLinus Torvalds error = -EBUSY; 27311da177e4SLinus Torvalds else { 27321da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2733bec1052eSAl Viro if (!error) { 27341da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2735bec1052eSAl Viro if (!error) 2736d83c49f3SAl Viro dont_mount(dentry); 2737bec1052eSAl Viro } 27381da177e4SLinus Torvalds } 27391b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27401da177e4SLinus Torvalds 27411da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27421da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2743ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27441da177e4SLinus Torvalds d_delete(dentry); 27451da177e4SLinus Torvalds } 27460eeca283SRobert Love 27471da177e4SLinus Torvalds return error; 27481da177e4SLinus Torvalds } 27491da177e4SLinus Torvalds 27501da177e4SLinus Torvalds /* 27511da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27521b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27531da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27541da177e4SLinus Torvalds * while waiting on the I/O. 27551da177e4SLinus Torvalds */ 27565590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27571da177e4SLinus Torvalds { 27582ad94ae6SAl Viro int error; 27591da177e4SLinus Torvalds char *name; 27601da177e4SLinus Torvalds struct dentry *dentry; 27611da177e4SLinus Torvalds struct nameidata nd; 27621da177e4SLinus Torvalds struct inode *inode = NULL; 27631da177e4SLinus Torvalds 27642ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27651da177e4SLinus Torvalds if (error) 27662ad94ae6SAl Viro return error; 27672ad94ae6SAl Viro 27681da177e4SLinus Torvalds error = -EISDIR; 27691da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27701da177e4SLinus Torvalds goto exit1; 27710612d9fbSOGAWA Hirofumi 27720612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27730612d9fbSOGAWA Hirofumi 27744ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 277549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27761da177e4SLinus Torvalds error = PTR_ERR(dentry); 27771da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27781da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 27791da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 27801da177e4SLinus Torvalds goto slashes; 27811da177e4SLinus Torvalds inode = dentry->d_inode; 27821da177e4SLinus Torvalds if (inode) 27837de9c6eeSAl Viro ihold(inode); 27840622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27850622753bSDave Hansen if (error) 27860622753bSDave Hansen goto exit2; 2787be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2788be6d3e56SKentaro Takeda if (error) 2789be6d3e56SKentaro Takeda goto exit3; 27904ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2791be6d3e56SKentaro Takeda exit3: 27920622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27931da177e4SLinus Torvalds exit2: 27941da177e4SLinus Torvalds dput(dentry); 27951da177e4SLinus Torvalds } 27964ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27971da177e4SLinus Torvalds if (inode) 27981da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27991da177e4SLinus Torvalds exit1: 28001d957f9bSJan Blunck path_put(&nd.path); 28011da177e4SLinus Torvalds putname(name); 28021da177e4SLinus Torvalds return error; 28031da177e4SLinus Torvalds 28041da177e4SLinus Torvalds slashes: 28051da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 28061da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 28071da177e4SLinus Torvalds goto exit2; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 28102e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 28115590ff0dSUlrich Drepper { 28125590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 28135590ff0dSUlrich Drepper return -EINVAL; 28145590ff0dSUlrich Drepper 28155590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 28165590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 28175590ff0dSUlrich Drepper 28185590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 28195590ff0dSUlrich Drepper } 28205590ff0dSUlrich Drepper 28213480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 28225590ff0dSUlrich Drepper { 28235590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 28245590ff0dSUlrich Drepper } 28255590ff0dSUlrich Drepper 2826db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 28271da177e4SLinus Torvalds { 2828a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28291da177e4SLinus Torvalds 28301da177e4SLinus Torvalds if (error) 28311da177e4SLinus Torvalds return error; 28321da177e4SLinus Torvalds 2833acfa4380SAl Viro if (!dir->i_op->symlink) 28341da177e4SLinus Torvalds return -EPERM; 28351da177e4SLinus Torvalds 28361da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28371da177e4SLinus Torvalds if (error) 28381da177e4SLinus Torvalds return error; 28391da177e4SLinus Torvalds 28401da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2841a74574aaSStephen Smalley if (!error) 2842f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28431da177e4SLinus Torvalds return error; 28441da177e4SLinus Torvalds } 28451da177e4SLinus Torvalds 28462e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28472e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28481da177e4SLinus Torvalds { 28492ad94ae6SAl Viro int error; 28501da177e4SLinus Torvalds char *from; 28511da177e4SLinus Torvalds char *to; 28526902d925SDave Hansen struct dentry *dentry; 28536902d925SDave Hansen struct nameidata nd; 28541da177e4SLinus Torvalds 28551da177e4SLinus Torvalds from = getname(oldname); 28561da177e4SLinus Torvalds if (IS_ERR(from)) 28571da177e4SLinus Torvalds return PTR_ERR(from); 28582ad94ae6SAl Viro 28592ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28602ad94ae6SAl Viro if (error) 28616902d925SDave Hansen goto out_putname; 28621da177e4SLinus Torvalds 28631da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28641da177e4SLinus Torvalds error = PTR_ERR(dentry); 28656902d925SDave Hansen if (IS_ERR(dentry)) 28666902d925SDave Hansen goto out_unlock; 28676902d925SDave Hansen 286875c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 286975c3f29dSDave Hansen if (error) 287075c3f29dSDave Hansen goto out_dput; 2871be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2872be6d3e56SKentaro Takeda if (error) 2873be6d3e56SKentaro Takeda goto out_drop_write; 2874db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2875be6d3e56SKentaro Takeda out_drop_write: 287675c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 287775c3f29dSDave Hansen out_dput: 28781da177e4SLinus Torvalds dput(dentry); 28796902d925SDave Hansen out_unlock: 28804ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28811d957f9bSJan Blunck path_put(&nd.path); 28821da177e4SLinus Torvalds putname(to); 28836902d925SDave Hansen out_putname: 28841da177e4SLinus Torvalds putname(from); 28851da177e4SLinus Torvalds return error; 28861da177e4SLinus Torvalds } 28871da177e4SLinus Torvalds 28883480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28895590ff0dSUlrich Drepper { 28905590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28915590ff0dSUlrich Drepper } 28925590ff0dSUlrich Drepper 28931da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28941da177e4SLinus Torvalds { 28951da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28961da177e4SLinus Torvalds int error; 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds if (!inode) 28991da177e4SLinus Torvalds return -ENOENT; 29001da177e4SLinus Torvalds 2901a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 29021da177e4SLinus Torvalds if (error) 29031da177e4SLinus Torvalds return error; 29041da177e4SLinus Torvalds 29051da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 29061da177e4SLinus Torvalds return -EXDEV; 29071da177e4SLinus Torvalds 29081da177e4SLinus Torvalds /* 29091da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 29101da177e4SLinus Torvalds */ 29111da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 29121da177e4SLinus Torvalds return -EPERM; 2913acfa4380SAl Viro if (!dir->i_op->link) 29141da177e4SLinus Torvalds return -EPERM; 29157e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 29161da177e4SLinus Torvalds return -EPERM; 29171da177e4SLinus Torvalds 29181da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 29191da177e4SLinus Torvalds if (error) 29201da177e4SLinus Torvalds return error; 29211da177e4SLinus Torvalds 29227e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2923aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2924aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2925aae8a97dSAneesh Kumar K.V error = -ENOENT; 2926aae8a97dSAneesh Kumar K.V else 29271da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 29287e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2929e31e14ecSStephen Smalley if (!error) 29307e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 29311da177e4SLinus Torvalds return error; 29321da177e4SLinus Torvalds } 29331da177e4SLinus Torvalds 29341da177e4SLinus Torvalds /* 29351da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29361da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29371da177e4SLinus Torvalds * newname. --KAB 29381da177e4SLinus Torvalds * 29391da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29401da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29411da177e4SLinus Torvalds * and other special files. --ADM 29421da177e4SLinus Torvalds */ 29432e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29442e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29451da177e4SLinus Torvalds { 29461da177e4SLinus Torvalds struct dentry *new_dentry; 29472d8f3038SAl Viro struct nameidata nd; 29482d8f3038SAl Viro struct path old_path; 294911a7b371SAneesh Kumar K.V int how = 0; 29501da177e4SLinus Torvalds int error; 29511da177e4SLinus Torvalds char *to; 29521da177e4SLinus Torvalds 295311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2954c04030e1SUlrich Drepper return -EINVAL; 295511a7b371SAneesh Kumar K.V /* 295611a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 295711a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 295811a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 295911a7b371SAneesh Kumar K.V */ 296011a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 296111a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 296211a7b371SAneesh Kumar K.V return -ENOENT; 296311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 296411a7b371SAneesh Kumar K.V } 2965c04030e1SUlrich Drepper 296611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 296711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 296811a7b371SAneesh Kumar K.V 296911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29701da177e4SLinus Torvalds if (error) 29712ad94ae6SAl Viro return error; 29722ad94ae6SAl Viro 29732ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29741da177e4SLinus Torvalds if (error) 29751da177e4SLinus Torvalds goto out; 29761da177e4SLinus Torvalds error = -EXDEV; 29772d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29781da177e4SLinus Torvalds goto out_release; 29791da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29801da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29816902d925SDave Hansen if (IS_ERR(new_dentry)) 29826902d925SDave Hansen goto out_unlock; 298375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 298475c3f29dSDave Hansen if (error) 298575c3f29dSDave Hansen goto out_dput; 2986be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2987be6d3e56SKentaro Takeda if (error) 2988be6d3e56SKentaro Takeda goto out_drop_write; 29892d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2990be6d3e56SKentaro Takeda out_drop_write: 299175c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 299275c3f29dSDave Hansen out_dput: 29931da177e4SLinus Torvalds dput(new_dentry); 29946902d925SDave Hansen out_unlock: 29954ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29961da177e4SLinus Torvalds out_release: 29971d957f9bSJan Blunck path_put(&nd.path); 29982ad94ae6SAl Viro putname(to); 29991da177e4SLinus Torvalds out: 30002d8f3038SAl Viro path_put(&old_path); 30011da177e4SLinus Torvalds 30021da177e4SLinus Torvalds return error; 30031da177e4SLinus Torvalds } 30041da177e4SLinus Torvalds 30053480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 30065590ff0dSUlrich Drepper { 3007c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 30085590ff0dSUlrich Drepper } 30095590ff0dSUlrich Drepper 30101da177e4SLinus Torvalds /* 30111da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 30121da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 30131da177e4SLinus Torvalds * Problems: 30141da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 30151da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 30161da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3017a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 30181da177e4SLinus Torvalds * story. 30191da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 30201b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 30211da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 30221da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3023a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 30241da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 30251da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 30261da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3027a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 30281da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 30291da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 30301da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 30311da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 30321da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 30331da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 30341da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 30351da177e4SLinus Torvalds * trick as in rmdir(). 30361da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 30371b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 30381da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3039c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 30401da177e4SLinus Torvalds * locking]. 30411da177e4SLinus Torvalds */ 304275c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30431da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30441da177e4SLinus Torvalds { 30451da177e4SLinus Torvalds int error = 0; 30461da177e4SLinus Torvalds struct inode *target; 30471da177e4SLinus Torvalds 30481da177e4SLinus Torvalds /* 30491da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30501da177e4SLinus Torvalds * we'll need to flip '..'. 30511da177e4SLinus Torvalds */ 30521da177e4SLinus Torvalds if (new_dir != old_dir) { 3053f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30541da177e4SLinus Torvalds if (error) 30551da177e4SLinus Torvalds return error; 30561da177e4SLinus Torvalds } 30571da177e4SLinus Torvalds 30581da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30591da177e4SLinus Torvalds if (error) 30601da177e4SLinus Torvalds return error; 30611da177e4SLinus Torvalds 30621da177e4SLinus Torvalds target = new_dentry->d_inode; 3063d83c49f3SAl Viro if (target) 30641b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30651da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30661da177e4SLinus Torvalds error = -EBUSY; 3067d83c49f3SAl Viro else { 3068d83c49f3SAl Viro if (target) 3069d83c49f3SAl Viro dentry_unhash(new_dentry); 30701da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3071d83c49f3SAl Viro } 30721da177e4SLinus Torvalds if (target) { 3073d83c49f3SAl Viro if (!error) { 30741da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3075d83c49f3SAl Viro dont_mount(new_dentry); 3076d83c49f3SAl Viro } 30771b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30781da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 30791da177e4SLinus Torvalds d_rehash(new_dentry); 30801da177e4SLinus Torvalds dput(new_dentry); 30811da177e4SLinus Torvalds } 3082e31e14ecSStephen Smalley if (!error) 3083349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30841da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30851da177e4SLinus Torvalds return error; 30861da177e4SLinus Torvalds } 30871da177e4SLinus Torvalds 308875c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30891da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30901da177e4SLinus Torvalds { 30911da177e4SLinus Torvalds struct inode *target; 30921da177e4SLinus Torvalds int error; 30931da177e4SLinus Torvalds 30941da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30951da177e4SLinus Torvalds if (error) 30961da177e4SLinus Torvalds return error; 30971da177e4SLinus Torvalds 30981da177e4SLinus Torvalds dget(new_dentry); 30991da177e4SLinus Torvalds target = new_dentry->d_inode; 31001da177e4SLinus Torvalds if (target) 31011b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 31021da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 31031da177e4SLinus Torvalds error = -EBUSY; 31041da177e4SLinus Torvalds else 31051da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 31061da177e4SLinus Torvalds if (!error) { 3107bec1052eSAl Viro if (target) 3108d83c49f3SAl Viro dont_mount(new_dentry); 3109349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 31101da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 31111da177e4SLinus Torvalds } 31121da177e4SLinus Torvalds if (target) 31131b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 31141da177e4SLinus Torvalds dput(new_dentry); 31151da177e4SLinus Torvalds return error; 31161da177e4SLinus Torvalds } 31171da177e4SLinus Torvalds 31181da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 31191da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31201da177e4SLinus Torvalds { 31211da177e4SLinus Torvalds int error; 31221da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 312359b0df21SEric Paris const unsigned char *old_name; 31241da177e4SLinus Torvalds 31251da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 31261da177e4SLinus Torvalds return 0; 31271da177e4SLinus Torvalds 31281da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 31291da177e4SLinus Torvalds if (error) 31301da177e4SLinus Torvalds return error; 31311da177e4SLinus Torvalds 31321da177e4SLinus Torvalds if (!new_dentry->d_inode) 3133a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 31341da177e4SLinus Torvalds else 31351da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31361da177e4SLinus Torvalds if (error) 31371da177e4SLinus Torvalds return error; 31381da177e4SLinus Torvalds 3139acfa4380SAl Viro if (!old_dir->i_op->rename) 31401da177e4SLinus Torvalds return -EPERM; 31411da177e4SLinus Torvalds 31420eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31430eeca283SRobert Love 31441da177e4SLinus Torvalds if (is_dir) 31451da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31461da177e4SLinus Torvalds else 31471da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3148123df294SAl Viro if (!error) 3149123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31505a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31510eeca283SRobert Love fsnotify_oldname_free(old_name); 31520eeca283SRobert Love 31531da177e4SLinus Torvalds return error; 31541da177e4SLinus Torvalds } 31551da177e4SLinus Torvalds 31562e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31572e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31581da177e4SLinus Torvalds { 31591da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31601da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31611da177e4SLinus Torvalds struct dentry *trap; 31621da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31632ad94ae6SAl Viro char *from; 31642ad94ae6SAl Viro char *to; 31652ad94ae6SAl Viro int error; 31661da177e4SLinus Torvalds 31672ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31681da177e4SLinus Torvalds if (error) 31691da177e4SLinus Torvalds goto exit; 31701da177e4SLinus Torvalds 31712ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31721da177e4SLinus Torvalds if (error) 31731da177e4SLinus Torvalds goto exit1; 31741da177e4SLinus Torvalds 31751da177e4SLinus Torvalds error = -EXDEV; 31764ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31771da177e4SLinus Torvalds goto exit2; 31781da177e4SLinus Torvalds 31794ac91378SJan Blunck old_dir = oldnd.path.dentry; 31801da177e4SLinus Torvalds error = -EBUSY; 31811da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31821da177e4SLinus Torvalds goto exit2; 31831da177e4SLinus Torvalds 31844ac91378SJan Blunck new_dir = newnd.path.dentry; 31851da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31861da177e4SLinus Torvalds goto exit2; 31871da177e4SLinus Torvalds 31880612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31890612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31904e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31910612d9fbSOGAWA Hirofumi 31921da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31931da177e4SLinus Torvalds 319449705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31951da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31961da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31971da177e4SLinus Torvalds goto exit3; 31981da177e4SLinus Torvalds /* source must exist */ 31991da177e4SLinus Torvalds error = -ENOENT; 32001da177e4SLinus Torvalds if (!old_dentry->d_inode) 32011da177e4SLinus Torvalds goto exit4; 32021da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 32031da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 32041da177e4SLinus Torvalds error = -ENOTDIR; 32051da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 32061da177e4SLinus Torvalds goto exit4; 32071da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 32081da177e4SLinus Torvalds goto exit4; 32091da177e4SLinus Torvalds } 32101da177e4SLinus Torvalds /* source should not be ancestor of target */ 32111da177e4SLinus Torvalds error = -EINVAL; 32121da177e4SLinus Torvalds if (old_dentry == trap) 32131da177e4SLinus Torvalds goto exit4; 321449705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 32151da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 32161da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 32171da177e4SLinus Torvalds goto exit4; 32181da177e4SLinus Torvalds /* target should not be an ancestor of source */ 32191da177e4SLinus Torvalds error = -ENOTEMPTY; 32201da177e4SLinus Torvalds if (new_dentry == trap) 32211da177e4SLinus Torvalds goto exit5; 32221da177e4SLinus Torvalds 32239079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 32249079b1ebSDave Hansen if (error) 32259079b1ebSDave Hansen goto exit5; 3226be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3227be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3228be6d3e56SKentaro Takeda if (error) 3229be6d3e56SKentaro Takeda goto exit6; 32301da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 32311da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3232be6d3e56SKentaro Takeda exit6: 32339079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 32341da177e4SLinus Torvalds exit5: 32351da177e4SLinus Torvalds dput(new_dentry); 32361da177e4SLinus Torvalds exit4: 32371da177e4SLinus Torvalds dput(old_dentry); 32381da177e4SLinus Torvalds exit3: 32391da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32401da177e4SLinus Torvalds exit2: 32411d957f9bSJan Blunck path_put(&newnd.path); 32422ad94ae6SAl Viro putname(to); 32431da177e4SLinus Torvalds exit1: 32441d957f9bSJan Blunck path_put(&oldnd.path); 32451da177e4SLinus Torvalds putname(from); 32462ad94ae6SAl Viro exit: 32471da177e4SLinus Torvalds return error; 32481da177e4SLinus Torvalds } 32491da177e4SLinus Torvalds 3250a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32515590ff0dSUlrich Drepper { 32525590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32535590ff0dSUlrich Drepper } 32545590ff0dSUlrich Drepper 32551da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32561da177e4SLinus Torvalds { 32571da177e4SLinus Torvalds int len; 32581da177e4SLinus Torvalds 32591da177e4SLinus Torvalds len = PTR_ERR(link); 32601da177e4SLinus Torvalds if (IS_ERR(link)) 32611da177e4SLinus Torvalds goto out; 32621da177e4SLinus Torvalds 32631da177e4SLinus Torvalds len = strlen(link); 32641da177e4SLinus Torvalds if (len > (unsigned) buflen) 32651da177e4SLinus Torvalds len = buflen; 32661da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32671da177e4SLinus Torvalds len = -EFAULT; 32681da177e4SLinus Torvalds out: 32691da177e4SLinus Torvalds return len; 32701da177e4SLinus Torvalds } 32711da177e4SLinus Torvalds 32721da177e4SLinus Torvalds /* 32731da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32741da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32751da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32761da177e4SLinus Torvalds */ 32771da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32781da177e4SLinus Torvalds { 32791da177e4SLinus Torvalds struct nameidata nd; 3280cc314eefSLinus Torvalds void *cookie; 3281694a1764SMarcin Slusarz int res; 3282cc314eefSLinus Torvalds 32831da177e4SLinus Torvalds nd.depth = 0; 3284cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3285694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3286694a1764SMarcin Slusarz return PTR_ERR(cookie); 3287694a1764SMarcin Slusarz 3288694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32891da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3290cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3291694a1764SMarcin Slusarz return res; 32921da177e4SLinus Torvalds } 32931da177e4SLinus Torvalds 32941da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32951da177e4SLinus Torvalds { 32961da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32971da177e4SLinus Torvalds } 32981da177e4SLinus Torvalds 32991da177e4SLinus Torvalds /* get the link contents into pagecache */ 33001da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 33011da177e4SLinus Torvalds { 3302ebd09abbSDuane Griffin char *kaddr; 33031da177e4SLinus Torvalds struct page *page; 33041da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3305090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 33061da177e4SLinus Torvalds if (IS_ERR(page)) 33076fe6900eSNick Piggin return (char*)page; 33081da177e4SLinus Torvalds *ppage = page; 3309ebd09abbSDuane Griffin kaddr = kmap(page); 3310ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3311ebd09abbSDuane Griffin return kaddr; 33121da177e4SLinus Torvalds } 33131da177e4SLinus Torvalds 33141da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 33151da177e4SLinus Torvalds { 33161da177e4SLinus Torvalds struct page *page = NULL; 33171da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 33181da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 33191da177e4SLinus Torvalds if (page) { 33201da177e4SLinus Torvalds kunmap(page); 33211da177e4SLinus Torvalds page_cache_release(page); 33221da177e4SLinus Torvalds } 33231da177e4SLinus Torvalds return res; 33241da177e4SLinus Torvalds } 33251da177e4SLinus Torvalds 3326cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 33271da177e4SLinus Torvalds { 3328cc314eefSLinus Torvalds struct page *page = NULL; 33291da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3330cc314eefSLinus Torvalds return page; 33311da177e4SLinus Torvalds } 33321da177e4SLinus Torvalds 3333cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 33341da177e4SLinus Torvalds { 3335cc314eefSLinus Torvalds struct page *page = cookie; 3336cc314eefSLinus Torvalds 3337cc314eefSLinus Torvalds if (page) { 33381da177e4SLinus Torvalds kunmap(page); 33391da177e4SLinus Torvalds page_cache_release(page); 33401da177e4SLinus Torvalds } 33411da177e4SLinus Torvalds } 33421da177e4SLinus Torvalds 334354566b2cSNick Piggin /* 334454566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 334554566b2cSNick Piggin */ 334654566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33471da177e4SLinus Torvalds { 33481da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33490adb25d2SKirill Korotaev struct page *page; 3350afddba49SNick Piggin void *fsdata; 3351beb497abSDmitriy Monakhov int err; 33521da177e4SLinus Torvalds char *kaddr; 335354566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 335454566b2cSNick Piggin if (nofs) 335554566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33561da177e4SLinus Torvalds 33577e53cac4SNeilBrown retry: 3358afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 335954566b2cSNick Piggin flags, &page, &fsdata); 33601da177e4SLinus Torvalds if (err) 3361afddba49SNick Piggin goto fail; 3362afddba49SNick Piggin 33631da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33641da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33651da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3366afddba49SNick Piggin 3367afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3368afddba49SNick Piggin page, fsdata); 33691da177e4SLinus Torvalds if (err < 0) 33701da177e4SLinus Torvalds goto fail; 3371afddba49SNick Piggin if (err < len-1) 3372afddba49SNick Piggin goto retry; 3373afddba49SNick Piggin 33741da177e4SLinus Torvalds mark_inode_dirty(inode); 33751da177e4SLinus Torvalds return 0; 33761da177e4SLinus Torvalds fail: 33771da177e4SLinus Torvalds return err; 33781da177e4SLinus Torvalds } 33791da177e4SLinus Torvalds 33800adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33810adb25d2SKirill Korotaev { 33820adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 338354566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33840adb25d2SKirill Korotaev } 33850adb25d2SKirill Korotaev 338692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33871da177e4SLinus Torvalds .readlink = generic_readlink, 33881da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33891da177e4SLinus Torvalds .put_link = page_put_link, 33901da177e4SLinus Torvalds }; 33911da177e4SLinus Torvalds 33922d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3393cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33941da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33951da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33961da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33971da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33981da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33991da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 34001da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 34011da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 34021da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 34030adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 34041da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 34051da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3406c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3407d1811465SAl Viro EXPORT_SYMBOL(kern_path); 340816f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3409f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 34108c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 34111da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 34121da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 34131da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 34141da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 34151da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 34161da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 34171da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 34181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 34191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 34201da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 34211da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 34221da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 34231da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 34241da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3425