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 740def4af30SAl Viro static __always_inline int 7417b9337aaSNick Piggin __do_follow_link(const struct path *link, struct nameidata *nd, void **p) 7421da177e4SLinus Torvalds { 7431da177e4SLinus Torvalds int error; 7447b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7451da177e4SLinus Torvalds 746844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 747844a3917SAl Viro 7487b9337aaSNick Piggin touch_atime(link->mnt, dentry); 7491da177e4SLinus Torvalds nd_set_link(nd, NULL); 750cd4e91d3SAl Viro 75187556ef1SDavid Howells if (link->mnt == nd->path.mnt) 7527b9337aaSNick Piggin mntget(link->mnt); 75331e6b01fSNick Piggin 75436f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 75536f3b4f6SAl Viro if (error) { 75636f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 75736f3b4f6SAl Viro path_put(&nd->path); 75836f3b4f6SAl Viro return error; 75936f3b4f6SAl Viro } 76036f3b4f6SAl Viro 76186acdca1SAl Viro nd->last_type = LAST_BIND; 762def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 763def4af30SAl Viro error = PTR_ERR(*p); 764def4af30SAl Viro if (!IS_ERR(*p)) { 7651da177e4SLinus Torvalds char *s = nd_get_link(nd); 766cc314eefSLinus Torvalds error = 0; 7671da177e4SLinus Torvalds if (s) 7681da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 769bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 77016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 771b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 772b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 773bcda7652SAl Viro /* stepped on a _really_ weird one */ 774bcda7652SAl Viro path_put(&nd->path); 775bcda7652SAl Viro error = -ELOOP; 776bcda7652SAl Viro } 777bcda7652SAl Viro } 7781da177e4SLinus Torvalds } 7791da177e4SLinus Torvalds return error; 7801da177e4SLinus Torvalds } 7811da177e4SLinus Torvalds 78231e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 78331e6b01fSNick Piggin { 78431e6b01fSNick Piggin struct vfsmount *parent; 78531e6b01fSNick Piggin struct dentry *mountpoint; 78631e6b01fSNick Piggin 78731e6b01fSNick Piggin parent = path->mnt->mnt_parent; 78831e6b01fSNick Piggin if (parent == path->mnt) 78931e6b01fSNick Piggin return 0; 79031e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 79131e6b01fSNick Piggin path->dentry = mountpoint; 79231e6b01fSNick Piggin path->mnt = parent; 79331e6b01fSNick Piggin return 1; 79431e6b01fSNick Piggin } 79531e6b01fSNick Piggin 796bab77ebfSAl Viro int follow_up(struct path *path) 7971da177e4SLinus Torvalds { 7981da177e4SLinus Torvalds struct vfsmount *parent; 7991da177e4SLinus Torvalds struct dentry *mountpoint; 80099b7db7bSNick Piggin 80199b7db7bSNick Piggin br_read_lock(vfsmount_lock); 802bab77ebfSAl Viro parent = path->mnt->mnt_parent; 803bab77ebfSAl Viro if (parent == path->mnt) { 80499b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 8051da177e4SLinus Torvalds return 0; 8061da177e4SLinus Torvalds } 8071da177e4SLinus Torvalds mntget(parent); 808bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 80999b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 810bab77ebfSAl Viro dput(path->dentry); 811bab77ebfSAl Viro path->dentry = mountpoint; 812bab77ebfSAl Viro mntput(path->mnt); 813bab77ebfSAl Viro path->mnt = parent; 8141da177e4SLinus Torvalds return 1; 8151da177e4SLinus Torvalds } 8161da177e4SLinus Torvalds 817b5c84bf6SNick Piggin /* 8189875cf80SDavid Howells * Perform an automount 8199875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 8209875cf80SDavid Howells * were called with. 8211da177e4SLinus Torvalds */ 8229875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 8239875cf80SDavid Howells bool *need_mntput) 82431e6b01fSNick Piggin { 8259875cf80SDavid Howells struct vfsmount *mnt; 826ea5b778aSDavid Howells int err; 8279875cf80SDavid Howells 8289875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 8299875cf80SDavid Howells return -EREMOTE; 8309875cf80SDavid Howells 8316f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 8326f45b656SDavid Howells * and this is the terminal part of the path. 8336f45b656SDavid Howells */ 8346f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 8356f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 8366f45b656SDavid Howells 8379875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 8389875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 8399875cf80SDavid Howells * or wants to open the mounted directory. 8409875cf80SDavid Howells * 8419875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 8429875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 8439875cf80SDavid Howells * appended a '/' to the name. 8449875cf80SDavid Howells */ 8459875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 8469875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 8479875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 8489875cf80SDavid Howells return -EISDIR; 8499875cf80SDavid Howells 8509875cf80SDavid Howells current->total_link_count++; 8519875cf80SDavid Howells if (current->total_link_count >= 40) 8529875cf80SDavid Howells return -ELOOP; 8539875cf80SDavid Howells 8549875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8559875cf80SDavid Howells if (IS_ERR(mnt)) { 8569875cf80SDavid Howells /* 8579875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8589875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 8599875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 8609875cf80SDavid Howells * 8619875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 8629875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 8639875cf80SDavid Howells * the path is inaccessible and we should say so. 8649875cf80SDavid Howells */ 8659875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 8669875cf80SDavid Howells return -EREMOTE; 8679875cf80SDavid Howells return PTR_ERR(mnt); 86831e6b01fSNick Piggin } 869ea5b778aSDavid Howells 8709875cf80SDavid Howells if (!mnt) /* mount collision */ 8719875cf80SDavid Howells return 0; 8729875cf80SDavid Howells 87319a167afSAl Viro err = finish_automount(mnt, path); 874ea5b778aSDavid Howells 875ea5b778aSDavid Howells switch (err) { 876ea5b778aSDavid Howells case -EBUSY: 877ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 87819a167afSAl Viro return 0; 879ea5b778aSDavid Howells case 0: 880463ffb2eSAl Viro dput(path->dentry); 8819875cf80SDavid Howells if (*need_mntput) 8829875cf80SDavid Howells mntput(path->mnt); 8839875cf80SDavid Howells path->mnt = mnt; 8849875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 8859875cf80SDavid Howells *need_mntput = true; 8869875cf80SDavid Howells return 0; 88719a167afSAl Viro default: 88819a167afSAl Viro return err; 8899875cf80SDavid Howells } 89019a167afSAl Viro 891ea5b778aSDavid Howells } 8929875cf80SDavid Howells 8939875cf80SDavid Howells /* 8949875cf80SDavid Howells * Handle a dentry that is managed in some way. 895cc53ce53SDavid Howells * - Flagged for transit management (autofs) 8969875cf80SDavid Howells * - Flagged as mountpoint 8979875cf80SDavid Howells * - Flagged as automount point 8989875cf80SDavid Howells * 8999875cf80SDavid Howells * This may only be called in refwalk mode. 9009875cf80SDavid Howells * 9019875cf80SDavid Howells * Serialization is taken care of in namespace.c 9029875cf80SDavid Howells */ 9039875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9049875cf80SDavid Howells { 9059875cf80SDavid Howells unsigned managed; 9069875cf80SDavid Howells bool need_mntput = false; 9079875cf80SDavid Howells int ret; 9089875cf80SDavid Howells 9099875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9109875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9119875cf80SDavid Howells * the components of that value change under us */ 9129875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9139875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9149875cf80SDavid Howells unlikely(managed != 0)) { 915cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 916cc53ce53SDavid Howells * being held. */ 917cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 918cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 919cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 920ab90911fSDavid Howells ret = path->dentry->d_op->d_manage(path->dentry, 921ab90911fSDavid Howells false, false); 922cc53ce53SDavid Howells if (ret < 0) 923cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 924cc53ce53SDavid Howells } 925cc53ce53SDavid Howells 9269875cf80SDavid Howells /* Transit to a mounted filesystem. */ 9279875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 9289875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9299875cf80SDavid Howells if (mounted) { 9309875cf80SDavid Howells dput(path->dentry); 9319875cf80SDavid Howells if (need_mntput) 932463ffb2eSAl Viro mntput(path->mnt); 933463ffb2eSAl Viro path->mnt = mounted; 934463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 9359875cf80SDavid Howells need_mntput = true; 9369875cf80SDavid Howells continue; 937463ffb2eSAl Viro } 938463ffb2eSAl Viro 9399875cf80SDavid Howells /* Something is mounted on this dentry in another 9409875cf80SDavid Howells * namespace and/or whatever was mounted there in this 9419875cf80SDavid Howells * namespace got unmounted before we managed to get the 9429875cf80SDavid Howells * vfsmount_lock */ 9431da177e4SLinus Torvalds } 9449875cf80SDavid Howells 9459875cf80SDavid Howells /* Handle an automount point */ 9469875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 9479875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 9489875cf80SDavid Howells if (ret < 0) 9499875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 9509875cf80SDavid Howells continue; 9519875cf80SDavid Howells } 9529875cf80SDavid Howells 9539875cf80SDavid Howells /* We didn't change the current path point */ 9549875cf80SDavid Howells break; 9559875cf80SDavid Howells } 9569875cf80SDavid Howells return 0; 9571da177e4SLinus Torvalds } 9581da177e4SLinus Torvalds 959cc53ce53SDavid Howells int follow_down_one(struct path *path) 9601da177e4SLinus Torvalds { 9611da177e4SLinus Torvalds struct vfsmount *mounted; 9621da177e4SLinus Torvalds 9631c755af4SAl Viro mounted = lookup_mnt(path); 9641da177e4SLinus Torvalds if (mounted) { 9659393bd07SAl Viro dput(path->dentry); 9669393bd07SAl Viro mntput(path->mnt); 9679393bd07SAl Viro path->mnt = mounted; 9689393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9691da177e4SLinus Torvalds return 1; 9701da177e4SLinus Torvalds } 9711da177e4SLinus Torvalds return 0; 9721da177e4SLinus Torvalds } 9731da177e4SLinus Torvalds 9749875cf80SDavid Howells /* 9759875cf80SDavid Howells * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we 976cc53ce53SDavid Howells * meet a managed dentry and we're not walking to "..". True is returned to 9779875cf80SDavid Howells * continue, false to abort. 9789875cf80SDavid Howells */ 9799875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 9809875cf80SDavid Howells struct inode **inode, bool reverse_transit) 9819875cf80SDavid Howells { 9829875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 9839875cf80SDavid Howells struct vfsmount *mounted; 984ab90911fSDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) && 985ab90911fSDavid Howells !reverse_transit && 986ab90911fSDavid Howells path->dentry->d_op->d_manage(path->dentry, false, true) < 0) 987ab90911fSDavid Howells return false; 9889875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 9899875cf80SDavid Howells if (!mounted) 9909875cf80SDavid Howells break; 9919875cf80SDavid Howells path->mnt = mounted; 9929875cf80SDavid Howells path->dentry = mounted->mnt_root; 9939875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 9949875cf80SDavid Howells *inode = path->dentry->d_inode; 9959875cf80SDavid Howells } 9969875cf80SDavid Howells 9979875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 9989875cf80SDavid Howells return reverse_transit; 9999875cf80SDavid Howells return true; 10009875cf80SDavid Howells } 10019875cf80SDavid Howells 100231e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 100331e6b01fSNick Piggin { 100431e6b01fSNick Piggin struct inode *inode = nd->inode; 100531e6b01fSNick Piggin 100631e6b01fSNick Piggin set_root_rcu(nd); 100731e6b01fSNick Piggin 100831e6b01fSNick Piggin while (1) { 100931e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 101031e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 101131e6b01fSNick Piggin break; 101231e6b01fSNick Piggin } 101331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 101431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 101531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 101631e6b01fSNick Piggin unsigned seq; 101731e6b01fSNick Piggin 101831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 101931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1020ef7562d5SAl Viro goto failed; 102131e6b01fSNick Piggin inode = parent->d_inode; 102231e6b01fSNick Piggin nd->path.dentry = parent; 102331e6b01fSNick Piggin nd->seq = seq; 102431e6b01fSNick Piggin break; 102531e6b01fSNick Piggin } 102631e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 102731e6b01fSNick Piggin break; 102831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 102931e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 103031e6b01fSNick Piggin } 10319875cf80SDavid Howells __follow_mount_rcu(nd, &nd->path, &inode, true); 103231e6b01fSNick Piggin nd->inode = inode; 103331e6b01fSNick Piggin return 0; 1034ef7562d5SAl Viro 1035ef7562d5SAl Viro failed: 1036ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 10375b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1038ef7562d5SAl Viro nd->root.mnt = NULL; 1039ef7562d5SAl Viro rcu_read_unlock(); 1040ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 1041ef7562d5SAl Viro return -ECHILD; 104231e6b01fSNick Piggin } 104331e6b01fSNick Piggin 10449875cf80SDavid Howells /* 1045cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1046cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1047cc53ce53SDavid Howells * caller is permitted to proceed or not. 1048cc53ce53SDavid Howells * 1049cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1050cc53ce53SDavid Howells * being true). 1051cc53ce53SDavid Howells */ 1052cc53ce53SDavid Howells int follow_down(struct path *path, bool mounting_here) 1053cc53ce53SDavid Howells { 1054cc53ce53SDavid Howells unsigned managed; 1055cc53ce53SDavid Howells int ret; 1056cc53ce53SDavid Howells 1057cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1058cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1059cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1060cc53ce53SDavid Howells * being held. 1061cc53ce53SDavid Howells * 1062cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1063cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1064cc53ce53SDavid Howells * other than its daemon the right to mount on its 1065cc53ce53SDavid Howells * superstructure. 1066cc53ce53SDavid Howells * 1067cc53ce53SDavid Howells * The filesystem may sleep at this point. 1068cc53ce53SDavid Howells */ 1069cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1070cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1071cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1072ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 1073ab90911fSDavid Howells path->dentry, mounting_here, false); 1074cc53ce53SDavid Howells if (ret < 0) 1075cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1076cc53ce53SDavid Howells } 1077cc53ce53SDavid Howells 1078cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1079cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1080cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1081cc53ce53SDavid Howells if (!mounted) 1082cc53ce53SDavid Howells break; 1083cc53ce53SDavid Howells dput(path->dentry); 1084cc53ce53SDavid Howells mntput(path->mnt); 1085cc53ce53SDavid Howells path->mnt = mounted; 1086cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1087cc53ce53SDavid Howells continue; 1088cc53ce53SDavid Howells } 1089cc53ce53SDavid Howells 1090cc53ce53SDavid Howells /* Don't handle automount points here */ 1091cc53ce53SDavid Howells break; 1092cc53ce53SDavid Howells } 1093cc53ce53SDavid Howells return 0; 1094cc53ce53SDavid Howells } 1095cc53ce53SDavid Howells 1096cc53ce53SDavid Howells /* 10979875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10989875cf80SDavid Howells */ 10999875cf80SDavid Howells static void follow_mount(struct path *path) 11009875cf80SDavid Howells { 11019875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11029875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11039875cf80SDavid Howells if (!mounted) 11049875cf80SDavid Howells break; 11059875cf80SDavid Howells dput(path->dentry); 11069875cf80SDavid Howells mntput(path->mnt); 11079875cf80SDavid Howells path->mnt = mounted; 11089875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11099875cf80SDavid Howells } 11109875cf80SDavid Howells } 11119875cf80SDavid Howells 111231e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11131da177e4SLinus Torvalds { 11142a737871SAl Viro set_root(nd); 1115e518ddb7SAndreas Mohr 11161da177e4SLinus Torvalds while(1) { 11174ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11181da177e4SLinus Torvalds 11192a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11202a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11211da177e4SLinus Torvalds break; 11221da177e4SLinus Torvalds } 11234ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11243088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11253088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11261da177e4SLinus Torvalds dput(old); 11271da177e4SLinus Torvalds break; 11281da177e4SLinus Torvalds } 11293088dd70SAl Viro if (!follow_up(&nd->path)) 11301da177e4SLinus Torvalds break; 11311da177e4SLinus Torvalds } 113279ed0226SAl Viro follow_mount(&nd->path); 113331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11341da177e4SLinus Torvalds } 11351da177e4SLinus Torvalds 11361da177e4SLinus Torvalds /* 1137baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1138baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1139baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1140baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1141baa03890SNick Piggin */ 1142baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1143baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1144baa03890SNick Piggin { 1145baa03890SNick Piggin struct inode *inode = parent->d_inode; 1146baa03890SNick Piggin struct dentry *dentry; 1147baa03890SNick Piggin struct dentry *old; 1148baa03890SNick Piggin 1149baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1150baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1151baa03890SNick Piggin return ERR_PTR(-ENOENT); 1152baa03890SNick Piggin 1153baa03890SNick Piggin dentry = d_alloc(parent, name); 1154baa03890SNick Piggin if (unlikely(!dentry)) 1155baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1156baa03890SNick Piggin 1157baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1158baa03890SNick Piggin if (unlikely(old)) { 1159baa03890SNick Piggin dput(dentry); 1160baa03890SNick Piggin dentry = old; 1161baa03890SNick Piggin } 1162baa03890SNick Piggin return dentry; 1163baa03890SNick Piggin } 1164baa03890SNick Piggin 1165baa03890SNick Piggin /* 11661da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11671da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11681da177e4SLinus Torvalds * It _is_ time-critical. 11691da177e4SLinus Torvalds */ 11701da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 117131e6b01fSNick Piggin struct path *path, struct inode **inode) 11721da177e4SLinus Torvalds { 11734ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 117431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11755a18fff2SAl Viro int need_reval = 1; 11765a18fff2SAl Viro int status = 1; 11779875cf80SDavid Howells int err; 11789875cf80SDavid Howells 11793cac260aSAl Viro /* 1180b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1181b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1182b04f784eSNick Piggin * do the non-racy lookup, below. 1183b04f784eSNick Piggin */ 118431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 118531e6b01fSNick Piggin unsigned seq; 118631e6b01fSNick Piggin *inode = nd->inode; 118731e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11885a18fff2SAl Viro if (!dentry) 11895a18fff2SAl Viro goto unlazy; 11905a18fff2SAl Viro 119131e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 119231e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 119331e6b01fSNick Piggin return -ECHILD; 119431e6b01fSNick Piggin nd->seq = seq; 11955a18fff2SAl Viro 119624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11975a18fff2SAl Viro status = d_revalidate(dentry, nd); 11985a18fff2SAl Viro if (unlikely(status <= 0)) { 11995a18fff2SAl Viro if (status != -ECHILD) 12005a18fff2SAl Viro need_reval = 0; 12015a18fff2SAl Viro goto unlazy; 12025a18fff2SAl Viro } 120324643087SAl Viro } 120431e6b01fSNick Piggin path->mnt = mnt; 120531e6b01fSNick Piggin path->dentry = dentry; 12069875cf80SDavid Howells if (likely(__follow_mount_rcu(nd, path, inode, false))) 12079875cf80SDavid Howells return 0; 12085a18fff2SAl Viro unlazy: 12095a18fff2SAl Viro if (dentry) { 12105a18fff2SAl Viro if (nameidata_dentry_drop_rcu(nd, dentry)) 12115a18fff2SAl Viro return -ECHILD; 12125a18fff2SAl Viro } else { 12139875cf80SDavid Howells if (nameidata_drop_rcu(nd)) 12149875cf80SDavid Howells return -ECHILD; 12159875cf80SDavid Howells } 12165a18fff2SAl Viro } else { 121731e6b01fSNick Piggin dentry = __d_lookup(parent, name); 121824643087SAl Viro } 12195a18fff2SAl Viro 12205a18fff2SAl Viro retry: 12215a18fff2SAl Viro if (unlikely(!dentry)) { 12225a18fff2SAl Viro struct inode *dir = parent->d_inode; 12235a18fff2SAl Viro BUG_ON(nd->inode != dir); 12245a18fff2SAl Viro 12255a18fff2SAl Viro mutex_lock(&dir->i_mutex); 12265a18fff2SAl Viro dentry = d_lookup(parent, name); 12275a18fff2SAl Viro if (likely(!dentry)) { 12285a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 12295a18fff2SAl Viro if (IS_ERR(dentry)) { 12305a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12315a18fff2SAl Viro return PTR_ERR(dentry); 12325a18fff2SAl Viro } 12335a18fff2SAl Viro /* known good */ 12345a18fff2SAl Viro need_reval = 0; 12355a18fff2SAl Viro status = 1; 12365a18fff2SAl Viro } 12375a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12385a18fff2SAl Viro } 12395a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12405a18fff2SAl Viro status = d_revalidate(dentry, nd); 12415a18fff2SAl Viro if (unlikely(status <= 0)) { 12425a18fff2SAl Viro if (status < 0) { 12435a18fff2SAl Viro dput(dentry); 12445a18fff2SAl Viro return status; 12455a18fff2SAl Viro } 12465a18fff2SAl Viro if (!d_invalidate(dentry)) { 12475a18fff2SAl Viro dput(dentry); 12485a18fff2SAl Viro dentry = NULL; 12495a18fff2SAl Viro need_reval = 1; 12505a18fff2SAl Viro goto retry; 12515a18fff2SAl Viro } 12525a18fff2SAl Viro } 12535a18fff2SAl Viro 12541da177e4SLinus Torvalds path->mnt = mnt; 12551da177e4SLinus Torvalds path->dentry = dentry; 12569875cf80SDavid Howells err = follow_managed(path, nd->flags); 125789312214SIan Kent if (unlikely(err < 0)) { 125889312214SIan Kent path_put_conditional(path, nd); 12599875cf80SDavid Howells return err; 126089312214SIan Kent } 126131e6b01fSNick Piggin *inode = path->dentry->d_inode; 12621da177e4SLinus Torvalds return 0; 12631da177e4SLinus Torvalds } 12641da177e4SLinus Torvalds 126552094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 126652094c8aSAl Viro { 126752094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 126852094c8aSAl Viro int err = exec_permission(nd->inode, IPERM_FLAG_RCU); 126952094c8aSAl Viro if (err != -ECHILD) 127052094c8aSAl Viro return err; 127152094c8aSAl Viro if (nameidata_drop_rcu(nd)) 127252094c8aSAl Viro return -ECHILD; 127352094c8aSAl Viro } 127452094c8aSAl Viro return exec_permission(nd->inode, 0); 127552094c8aSAl Viro } 127652094c8aSAl Viro 12779856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12789856fa1bSAl Viro { 12799856fa1bSAl Viro if (type == LAST_DOTDOT) { 12809856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12819856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12829856fa1bSAl Viro return -ECHILD; 12839856fa1bSAl Viro } else 12849856fa1bSAl Viro follow_dotdot(nd); 12859856fa1bSAl Viro } 12869856fa1bSAl Viro return 0; 12879856fa1bSAl Viro } 12889856fa1bSAl Viro 1289951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1290951361f9SAl Viro { 1291951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1292951361f9SAl Viro path_put(&nd->path); 1293951361f9SAl Viro } else { 1294951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12955b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1296951361f9SAl Viro nd->root.mnt = NULL; 1297951361f9SAl Viro rcu_read_unlock(); 1298951361f9SAl Viro br_read_unlock(vfsmount_lock); 1299951361f9SAl Viro } 1300951361f9SAl Viro } 1301951361f9SAl Viro 1302ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1303ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1304ce57dfc1SAl Viro { 1305ce57dfc1SAl Viro struct inode *inode; 1306ce57dfc1SAl Viro int err; 1307ce57dfc1SAl Viro /* 1308ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1309ce57dfc1SAl Viro * to be able to know about the current root directory and 1310ce57dfc1SAl Viro * parent relationships. 1311ce57dfc1SAl Viro */ 1312ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1313ce57dfc1SAl Viro return handle_dots(nd, type); 1314ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1315ce57dfc1SAl Viro if (unlikely(err)) { 1316ce57dfc1SAl Viro terminate_walk(nd); 1317ce57dfc1SAl Viro return err; 1318ce57dfc1SAl Viro } 1319ce57dfc1SAl Viro if (!inode) { 1320ce57dfc1SAl Viro path_to_nameidata(path, nd); 1321ce57dfc1SAl Viro terminate_walk(nd); 1322ce57dfc1SAl Viro return -ENOENT; 1323ce57dfc1SAl Viro } 1324ce57dfc1SAl Viro if (unlikely(inode->i_op->follow_link) && follow) { 1325ce57dfc1SAl Viro if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry)) 1326ce57dfc1SAl Viro return -ECHILD; 1327ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1328ce57dfc1SAl Viro return 1; 1329ce57dfc1SAl Viro } 1330ce57dfc1SAl Viro path_to_nameidata(path, nd); 1331ce57dfc1SAl Viro nd->inode = inode; 1332ce57dfc1SAl Viro return 0; 1333ce57dfc1SAl Viro } 1334ce57dfc1SAl Viro 13351da177e4SLinus Torvalds /* 1336b356379aSAl Viro * This limits recursive symlink follows to 8, while 1337b356379aSAl Viro * limiting consecutive symlinks to 40. 1338b356379aSAl Viro * 1339b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1340b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1341b356379aSAl Viro */ 1342b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1343b356379aSAl Viro { 1344b356379aSAl Viro int res; 1345b356379aSAl Viro 1346b356379aSAl Viro BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1347b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1348b356379aSAl Viro path_put_conditional(path, nd); 1349b356379aSAl Viro path_put(&nd->path); 1350b356379aSAl Viro return -ELOOP; 1351b356379aSAl Viro } 1352b356379aSAl Viro 1353b356379aSAl Viro nd->depth++; 1354b356379aSAl Viro current->link_count++; 1355b356379aSAl Viro 1356b356379aSAl Viro do { 1357b356379aSAl Viro struct path link = *path; 1358b356379aSAl Viro void *cookie; 1359b356379aSAl Viro if (unlikely(current->total_link_count >= 40)) { 1360b356379aSAl Viro path_put_conditional(path, nd); 1361b356379aSAl Viro path_put(&nd->path); 1362b356379aSAl Viro res = -ELOOP; 1363b356379aSAl Viro break; 1364b356379aSAl Viro } 1365b356379aSAl Viro cond_resched(); 1366b356379aSAl Viro current->total_link_count++; 1367b356379aSAl Viro res = __do_follow_link(&link, nd, &cookie); 1368b356379aSAl Viro if (!res) 1369b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1370b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1371b356379aSAl Viro if (!IS_ERR(cookie) && link.dentry->d_inode->i_op->put_link) 1372b356379aSAl Viro link.dentry->d_inode->i_op->put_link(link.dentry, nd, cookie); 1373b356379aSAl Viro path_put(&link); 1374b356379aSAl Viro } while (res > 0); 1375b356379aSAl Viro 1376b356379aSAl Viro current->link_count--; 1377b356379aSAl Viro nd->depth--; 1378b356379aSAl Viro return res; 1379b356379aSAl Viro } 1380b356379aSAl Viro 1381b356379aSAl Viro /* 13821da177e4SLinus Torvalds * Name resolution. 1383ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1384ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13851da177e4SLinus Torvalds * 1386ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1387ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13881da177e4SLinus Torvalds */ 13896de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13901da177e4SLinus Torvalds { 13911da177e4SLinus Torvalds struct path next; 13921da177e4SLinus Torvalds int err; 13931da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13941da177e4SLinus Torvalds 13951da177e4SLinus Torvalds while (*name=='/') 13961da177e4SLinus Torvalds name++; 13971da177e4SLinus Torvalds if (!*name) 1398086e183aSAl Viro return 0; 13991da177e4SLinus Torvalds 14001da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 14011da177e4SLinus Torvalds for(;;) { 14021da177e4SLinus Torvalds unsigned long hash; 14031da177e4SLinus Torvalds struct qstr this; 14041da177e4SLinus Torvalds unsigned int c; 1405fe479a58SAl Viro int type; 14061da177e4SLinus Torvalds 1407cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 140852094c8aSAl Viro 140952094c8aSAl Viro err = may_lookup(nd); 14101da177e4SLinus Torvalds if (err) 14111da177e4SLinus Torvalds break; 14121da177e4SLinus Torvalds 14131da177e4SLinus Torvalds this.name = name; 14141da177e4SLinus Torvalds c = *(const unsigned char *)name; 14151da177e4SLinus Torvalds 14161da177e4SLinus Torvalds hash = init_name_hash(); 14171da177e4SLinus Torvalds do { 14181da177e4SLinus Torvalds name++; 14191da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 14201da177e4SLinus Torvalds c = *(const unsigned char *)name; 14211da177e4SLinus Torvalds } while (c && (c != '/')); 14221da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14231da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14241da177e4SLinus Torvalds 1425fe479a58SAl Viro type = LAST_NORM; 1426fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1427fe479a58SAl Viro case 2: 142816c2cd71SAl Viro if (this.name[1] == '.') { 1429fe479a58SAl Viro type = LAST_DOTDOT; 143016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 143116c2cd71SAl Viro } 1432fe479a58SAl Viro break; 1433fe479a58SAl Viro case 1: 1434fe479a58SAl Viro type = LAST_DOT; 1435fe479a58SAl Viro } 14365a202bcdSAl Viro if (likely(type == LAST_NORM)) { 14375a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 143816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14395a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14405a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14415a202bcdSAl Viro &this); 14425a202bcdSAl Viro if (err < 0) 14435a202bcdSAl Viro break; 14445a202bcdSAl Viro } 14455a202bcdSAl Viro } 1446fe479a58SAl Viro 14471da177e4SLinus Torvalds /* remove trailing slashes? */ 14481da177e4SLinus Torvalds if (!c) 14491da177e4SLinus Torvalds goto last_component; 14501da177e4SLinus Torvalds while (*++name == '/'); 14511da177e4SLinus Torvalds if (!*name) 1452b356379aSAl Viro goto last_component; 14531da177e4SLinus Torvalds 1454ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1455ce57dfc1SAl Viro if (err < 0) 1456ce57dfc1SAl Viro return err; 1457fe479a58SAl Viro 1458ce57dfc1SAl Viro if (err) { 1459b356379aSAl Viro err = nested_symlink(&next, nd); 14601da177e4SLinus Torvalds if (err) 1461a7472babSAl Viro return err; 146231e6b01fSNick Piggin } 14631da177e4SLinus Torvalds err = -ENOTDIR; 146431e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14651da177e4SLinus Torvalds break; 14661da177e4SLinus Torvalds continue; 14671da177e4SLinus Torvalds /* here ends the main loop */ 14681da177e4SLinus Torvalds 14691da177e4SLinus Torvalds last_component: 1470f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1471f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 1472ce57dfc1SAl Viro nd->last = this; 1473ce57dfc1SAl Viro nd->last_type = type; 1474ce57dfc1SAl Viro return 0; 1475ce57dfc1SAl Viro } 1476951361f9SAl Viro terminate_walk(nd); 14771da177e4SLinus Torvalds return err; 14781da177e4SLinus Torvalds } 14791da177e4SLinus Torvalds 148070e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 148170e9b357SAl Viro struct nameidata *nd, struct file **fp) 148231e6b01fSNick Piggin { 148331e6b01fSNick Piggin int retval = 0; 148431e6b01fSNick Piggin int fput_needed; 148531e6b01fSNick Piggin struct file *file; 148631e6b01fSNick Piggin 148731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 148816c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 148931e6b01fSNick Piggin nd->depth = 0; 14905b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14915b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 149273d049a4SAl Viro if (*name) { 14935b6ca027SAl Viro if (!inode->i_op->lookup) 14945b6ca027SAl Viro return -ENOTDIR; 14955b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14965b6ca027SAl Viro if (retval) 14975b6ca027SAl Viro return retval; 149873d049a4SAl Viro } 14995b6ca027SAl Viro nd->path = nd->root; 15005b6ca027SAl Viro nd->inode = inode; 15015b6ca027SAl Viro if (flags & LOOKUP_RCU) { 15025b6ca027SAl Viro br_read_lock(vfsmount_lock); 15035b6ca027SAl Viro rcu_read_lock(); 15045b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 15055b6ca027SAl Viro } else { 15065b6ca027SAl Viro path_get(&nd->path); 15075b6ca027SAl Viro } 15085b6ca027SAl Viro return 0; 15095b6ca027SAl Viro } 15105b6ca027SAl Viro 151131e6b01fSNick Piggin nd->root.mnt = NULL; 151231e6b01fSNick Piggin 151331e6b01fSNick Piggin if (*name=='/') { 1514e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 151531e6b01fSNick Piggin br_read_lock(vfsmount_lock); 151631e6b01fSNick Piggin rcu_read_lock(); 1517e41f7d4eSAl Viro set_root_rcu(nd); 1518e41f7d4eSAl Viro } else { 1519e41f7d4eSAl Viro set_root(nd); 1520e41f7d4eSAl Viro path_get(&nd->root); 1521e41f7d4eSAl Viro } 152231e6b01fSNick Piggin nd->path = nd->root; 152331e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1524e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 152531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1526c28cc364SNick Piggin unsigned seq; 152731e6b01fSNick Piggin 152831e6b01fSNick Piggin br_read_lock(vfsmount_lock); 152931e6b01fSNick Piggin rcu_read_lock(); 153031e6b01fSNick Piggin 1531c28cc364SNick Piggin do { 1532c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 153331e6b01fSNick Piggin nd->path = fs->pwd; 1534c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1535c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1536e41f7d4eSAl Viro } else { 1537e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1538e41f7d4eSAl Viro } 153931e6b01fSNick Piggin } else { 154031e6b01fSNick Piggin struct dentry *dentry; 154131e6b01fSNick Piggin 15421abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 154331e6b01fSNick Piggin retval = -EBADF; 154431e6b01fSNick Piggin if (!file) 154531e6b01fSNick Piggin goto out_fail; 154631e6b01fSNick Piggin 154731e6b01fSNick Piggin dentry = file->f_path.dentry; 154831e6b01fSNick Piggin 1549f52e0c11SAl Viro if (*name) { 155031e6b01fSNick Piggin retval = -ENOTDIR; 155131e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 155231e6b01fSNick Piggin goto fput_fail; 155331e6b01fSNick Piggin 155431e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 155531e6b01fSNick Piggin if (retval) 155631e6b01fSNick Piggin goto fput_fail; 1557f52e0c11SAl Viro } 155831e6b01fSNick Piggin 155931e6b01fSNick Piggin nd->path = file->f_path; 1560e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 156131e6b01fSNick Piggin if (fput_needed) 156270e9b357SAl Viro *fp = file; 1563c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 156431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 156531e6b01fSNick Piggin rcu_read_lock(); 15665590ff0dSUlrich Drepper } else { 15675dd784d0SJan Blunck path_get(&file->f_path); 15685590ff0dSUlrich Drepper fput_light(file, fput_needed); 15691da177e4SLinus Torvalds } 1570e41f7d4eSAl Viro } 1571e41f7d4eSAl Viro 157231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15739b4a9b14SAl Viro return 0; 15742dfdd266SJosef 'Jeff' Sipek 15759b4a9b14SAl Viro fput_fail: 15769b4a9b14SAl Viro fput_light(file, fput_needed); 15779b4a9b14SAl Viro out_fail: 15789b4a9b14SAl Viro return retval; 15799b4a9b14SAl Viro } 15809b4a9b14SAl Viro 1581bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1582bd92d7feSAl Viro { 1583bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1584bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1585bd92d7feSAl Viro 1586bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1587bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1588bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1589bd92d7feSAl Viro } 1590bd92d7feSAl Viro 15919b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1592ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15939b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15949b4a9b14SAl Viro { 159570e9b357SAl Viro struct file *base = NULL; 1596bd92d7feSAl Viro struct path path; 1597bd92d7feSAl Viro int err; 159831e6b01fSNick Piggin 159931e6b01fSNick Piggin /* 160031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 160131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 160231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 160331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 160431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 160531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 160631e6b01fSNick Piggin * analogue, foo_rcu(). 160731e6b01fSNick Piggin * 160831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 160931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 161031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 161131e6b01fSNick Piggin * be able to complete). 161231e6b01fSNick Piggin */ 1613bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1614ee0827cdSAl Viro 1615bd92d7feSAl Viro if (unlikely(err)) 1616bd92d7feSAl Viro return err; 1617ee0827cdSAl Viro 1618ee0827cdSAl Viro current->total_link_count = 0; 1619bd92d7feSAl Viro err = link_path_walk(name, nd); 1620bd92d7feSAl Viro 1621bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1622bd92d7feSAl Viro int count = 0; 1623bd92d7feSAl Viro err = lookup_last(nd, &path); 1624bd92d7feSAl Viro while (err > 0) { 1625bd92d7feSAl Viro void *cookie; 1626bd92d7feSAl Viro struct path link = path; 1627bd92d7feSAl Viro struct inode *inode = link.dentry->d_inode; 1628bd92d7feSAl Viro 1629bd92d7feSAl Viro if (count++ > 32) { 1630bd92d7feSAl Viro path_put_conditional(&path, nd); 1631bd92d7feSAl Viro path_put(&nd->path); 1632bd92d7feSAl Viro err = -ELOOP; 1633bd92d7feSAl Viro break; 1634bd92d7feSAl Viro } 1635bd92d7feSAl Viro cond_resched(); 1636bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1637bd92d7feSAl Viro err = __do_follow_link(&link, nd, &cookie); 1638bd92d7feSAl Viro if (!err) 1639bd92d7feSAl Viro err = lookup_last(nd, &path); 1640bd92d7feSAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 1641bd92d7feSAl Viro inode->i_op->put_link(link.dentry, nd, cookie); 1642bd92d7feSAl Viro path_put(&link); 1643bd92d7feSAl Viro } 1644bd92d7feSAl Viro } 1645ee0827cdSAl Viro 1646ee0827cdSAl Viro if (nd->flags & LOOKUP_RCU) { 16474455ca62SAl Viro /* went all way through without dropping RCU */ 1648bd92d7feSAl Viro BUG_ON(err); 1649086e183aSAl Viro if (nameidata_drop_rcu_last(nd)) 1650bd92d7feSAl Viro err = -ECHILD; 1651086e183aSAl Viro } 165231e6b01fSNick Piggin 1653bd92d7feSAl Viro if (!err) 1654bd92d7feSAl Viro err = handle_reval_path(nd); 1655bd92d7feSAl Viro 1656bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1657bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1658bd92d7feSAl Viro path_put(&nd->path); 1659bd92d7feSAl Viro return -ENOTDIR; 1660bd92d7feSAl Viro } 1661bd92d7feSAl Viro } 166216c2cd71SAl Viro 166370e9b357SAl Viro if (base) 166470e9b357SAl Viro fput(base); 1665ee0827cdSAl Viro 16665b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 166731e6b01fSNick Piggin path_put(&nd->root); 166831e6b01fSNick Piggin nd->root.mnt = NULL; 166931e6b01fSNick Piggin } 1670bd92d7feSAl Viro return err; 167131e6b01fSNick Piggin } 167231e6b01fSNick Piggin 1673ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1674ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1675ee0827cdSAl Viro { 1676ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1677ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1678ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1679ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1680ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1681ee0827cdSAl Viro 168231e6b01fSNick Piggin if (likely(!retval)) { 168331e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 168431e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 168531e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 168631e6b01fSNick Piggin } 168731e6b01fSNick Piggin } 1688170aa3d0SUlrich Drepper return retval; 16891da177e4SLinus Torvalds } 16901da177e4SLinus Torvalds 1691c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16925590ff0dSUlrich Drepper { 1693c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16945590ff0dSUlrich Drepper } 16955590ff0dSUlrich Drepper 1696d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1697d1811465SAl Viro { 1698d1811465SAl Viro struct nameidata nd; 1699d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1700d1811465SAl Viro if (!res) 1701d1811465SAl Viro *path = nd.path; 1702d1811465SAl Viro return res; 1703d1811465SAl Viro } 1704d1811465SAl Viro 170516f18200SJosef 'Jeff' Sipek /** 170616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 170716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 170816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 170916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 171016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 171116f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 171216f18200SJosef 'Jeff' Sipek */ 171316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 171416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 171516f18200SJosef 'Jeff' Sipek struct nameidata *nd) 171616f18200SJosef 'Jeff' Sipek { 17175b6ca027SAl Viro nd->root.dentry = dentry; 17185b6ca027SAl Viro nd->root.mnt = mnt; 17195b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 17205b6ca027SAl Viro return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); 172116f18200SJosef 'Jeff' Sipek } 172216f18200SJosef 'Jeff' Sipek 1723eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1724eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 17251da177e4SLinus Torvalds { 172681fca444SChristoph Hellwig struct inode *inode = base->d_inode; 17271da177e4SLinus Torvalds struct dentry *dentry; 17281da177e4SLinus Torvalds int err; 17291da177e4SLinus Torvalds 1730b74c79e9SNick Piggin err = exec_permission(inode, 0); 173181fca444SChristoph Hellwig if (err) 173281fca444SChristoph Hellwig return ERR_PTR(err); 17331da177e4SLinus Torvalds 17341da177e4SLinus Torvalds /* 1735b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1736b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1737b04f784eSNick Piggin * a double lookup. 17386e6b1bd1SAl Viro */ 17396e6b1bd1SAl Viro dentry = d_lookup(base, name); 17406e6b1bd1SAl Viro 1741fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 17426e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 17436e6b1bd1SAl Viro 17441da177e4SLinus Torvalds if (!dentry) 1745baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17465a202bcdSAl Viro 17471da177e4SLinus Torvalds return dentry; 17481da177e4SLinus Torvalds } 17491da177e4SLinus Torvalds 1750057f6c01SJames Morris /* 1751057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1752057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1753057f6c01SJames Morris * SMP-safe. 1754057f6c01SJames Morris */ 1755a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17561da177e4SLinus Torvalds { 17574ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17581da177e4SLinus Torvalds } 17591da177e4SLinus Torvalds 1760eead1911SChristoph Hellwig /** 1761a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1762eead1911SChristoph Hellwig * @name: pathname component to lookup 1763eead1911SChristoph Hellwig * @base: base directory to lookup from 1764eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1765eead1911SChristoph Hellwig * 1766a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1767a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1768eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1769eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1770eead1911SChristoph Hellwig */ 1771057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1772057f6c01SJames Morris { 1773057f6c01SJames Morris struct qstr this; 17746a96ba54SAl Viro unsigned long hash; 17756a96ba54SAl Viro unsigned int c; 1776057f6c01SJames Morris 17772f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17782f9092e1SDavid Woodhouse 17796a96ba54SAl Viro this.name = name; 17806a96ba54SAl Viro this.len = len; 17816a96ba54SAl Viro if (!len) 17826a96ba54SAl Viro return ERR_PTR(-EACCES); 17836a96ba54SAl Viro 17846a96ba54SAl Viro hash = init_name_hash(); 17856a96ba54SAl Viro while (len--) { 17866a96ba54SAl Viro c = *(const unsigned char *)name++; 17876a96ba54SAl Viro if (c == '/' || c == '\0') 17886a96ba54SAl Viro return ERR_PTR(-EACCES); 17896a96ba54SAl Viro hash = partial_name_hash(c, hash); 17906a96ba54SAl Viro } 17916a96ba54SAl Viro this.hash = end_name_hash(hash); 17925a202bcdSAl Viro /* 17935a202bcdSAl Viro * See if the low-level filesystem might want 17945a202bcdSAl Viro * to use its own hash.. 17955a202bcdSAl Viro */ 17965a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17975a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17985a202bcdSAl Viro if (err < 0) 17995a202bcdSAl Viro return ERR_PTR(err); 18005a202bcdSAl Viro } 1801eead1911SChristoph Hellwig 180249705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1803057f6c01SJames Morris } 1804057f6c01SJames Morris 18052d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 18062d8f3038SAl Viro struct path *path) 18071da177e4SLinus Torvalds { 18082d8f3038SAl Viro struct nameidata nd; 1809f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 18101da177e4SLinus Torvalds int err = PTR_ERR(tmp); 18111da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 18122d8f3038SAl Viro 18132d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18142d8f3038SAl Viro 18152d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 18161da177e4SLinus Torvalds putname(tmp); 18172d8f3038SAl Viro if (!err) 18182d8f3038SAl Viro *path = nd.path; 18191da177e4SLinus Torvalds } 18201da177e4SLinus Torvalds return err; 18211da177e4SLinus Torvalds } 18221da177e4SLinus Torvalds 18232ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 18242ad94ae6SAl Viro struct nameidata *nd, char **name) 18252ad94ae6SAl Viro { 18262ad94ae6SAl Viro char *s = getname(path); 18272ad94ae6SAl Viro int error; 18282ad94ae6SAl Viro 18292ad94ae6SAl Viro if (IS_ERR(s)) 18302ad94ae6SAl Viro return PTR_ERR(s); 18312ad94ae6SAl Viro 18322ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 18332ad94ae6SAl Viro if (error) 18342ad94ae6SAl Viro putname(s); 18352ad94ae6SAl Viro else 18362ad94ae6SAl Viro *name = s; 18372ad94ae6SAl Viro 18382ad94ae6SAl Viro return error; 18392ad94ae6SAl Viro } 18402ad94ae6SAl Viro 18411da177e4SLinus Torvalds /* 18421da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18431da177e4SLinus Torvalds * minimal. 18441da177e4SLinus Torvalds */ 18451da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18461da177e4SLinus Torvalds { 1847da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1848da9592edSDavid Howells 18491da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18501da177e4SLinus Torvalds return 0; 1851da9592edSDavid Howells if (inode->i_uid == fsuid) 18521da177e4SLinus Torvalds return 0; 1853da9592edSDavid Howells if (dir->i_uid == fsuid) 18541da177e4SLinus Torvalds return 0; 18551da177e4SLinus Torvalds return !capable(CAP_FOWNER); 18561da177e4SLinus Torvalds } 18571da177e4SLinus Torvalds 18581da177e4SLinus Torvalds /* 18591da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18601da177e4SLinus Torvalds * whether the type of victim is right. 18611da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18621da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18631da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18641da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18651da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18661da177e4SLinus Torvalds * a. be owner of dir, or 18671da177e4SLinus Torvalds * b. be owner of victim, or 18681da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18691da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18701da177e4SLinus Torvalds * links pointing to it. 18711da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18721da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18731da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18741da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18751da177e4SLinus Torvalds * nfs_async_unlink(). 18761da177e4SLinus Torvalds */ 1877858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18781da177e4SLinus Torvalds { 18791da177e4SLinus Torvalds int error; 18801da177e4SLinus Torvalds 18811da177e4SLinus Torvalds if (!victim->d_inode) 18821da177e4SLinus Torvalds return -ENOENT; 18831da177e4SLinus Torvalds 18841da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1885cccc6bbaSAl Viro audit_inode_child(victim, dir); 18861da177e4SLinus Torvalds 1887f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18881da177e4SLinus Torvalds if (error) 18891da177e4SLinus Torvalds return error; 18901da177e4SLinus Torvalds if (IS_APPEND(dir)) 18911da177e4SLinus Torvalds return -EPERM; 18921da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1893f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18941da177e4SLinus Torvalds return -EPERM; 18951da177e4SLinus Torvalds if (isdir) { 18961da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18971da177e4SLinus Torvalds return -ENOTDIR; 18981da177e4SLinus Torvalds if (IS_ROOT(victim)) 18991da177e4SLinus Torvalds return -EBUSY; 19001da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 19011da177e4SLinus Torvalds return -EISDIR; 19021da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19031da177e4SLinus Torvalds return -ENOENT; 19041da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 19051da177e4SLinus Torvalds return -EBUSY; 19061da177e4SLinus Torvalds return 0; 19071da177e4SLinus Torvalds } 19081da177e4SLinus Torvalds 19091da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 19101da177e4SLinus Torvalds * dir. 19111da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 19121da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 19131da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 19141da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 19151da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 19161da177e4SLinus Torvalds */ 1917a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 19181da177e4SLinus Torvalds { 19191da177e4SLinus Torvalds if (child->d_inode) 19201da177e4SLinus Torvalds return -EEXIST; 19211da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19221da177e4SLinus Torvalds return -ENOENT; 1923f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 19241da177e4SLinus Torvalds } 19251da177e4SLinus Torvalds 19261da177e4SLinus Torvalds /* 19271da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 19281da177e4SLinus Torvalds */ 19291da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 19301da177e4SLinus Torvalds { 19311da177e4SLinus Torvalds struct dentry *p; 19321da177e4SLinus Torvalds 19331da177e4SLinus Torvalds if (p1 == p2) { 1934f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 19351da177e4SLinus Torvalds return NULL; 19361da177e4SLinus Torvalds } 19371da177e4SLinus Torvalds 1938a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19391da177e4SLinus Torvalds 1940e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1941e2761a11SOGAWA Hirofumi if (p) { 1942f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1943f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19441da177e4SLinus Torvalds return p; 19451da177e4SLinus Torvalds } 19461da177e4SLinus Torvalds 1947e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1948e2761a11SOGAWA Hirofumi if (p) { 1949f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1950f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19511da177e4SLinus Torvalds return p; 19521da177e4SLinus Torvalds } 19531da177e4SLinus Torvalds 1954f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1955f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19561da177e4SLinus Torvalds return NULL; 19571da177e4SLinus Torvalds } 19581da177e4SLinus Torvalds 19591da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19601da177e4SLinus Torvalds { 19611b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19621da177e4SLinus Torvalds if (p1 != p2) { 19631b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1964a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19651da177e4SLinus Torvalds } 19661da177e4SLinus Torvalds } 19671da177e4SLinus Torvalds 19681da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19691da177e4SLinus Torvalds struct nameidata *nd) 19701da177e4SLinus Torvalds { 1971a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19721da177e4SLinus Torvalds 19731da177e4SLinus Torvalds if (error) 19741da177e4SLinus Torvalds return error; 19751da177e4SLinus Torvalds 1976acfa4380SAl Viro if (!dir->i_op->create) 19771da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19781da177e4SLinus Torvalds mode &= S_IALLUGO; 19791da177e4SLinus Torvalds mode |= S_IFREG; 19801da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19811da177e4SLinus Torvalds if (error) 19821da177e4SLinus Torvalds return error; 19831da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1984a74574aaSStephen Smalley if (!error) 1985f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19861da177e4SLinus Torvalds return error; 19871da177e4SLinus Torvalds } 19881da177e4SLinus Torvalds 198973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19901da177e4SLinus Torvalds { 19913fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19921da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19931da177e4SLinus Torvalds int error; 19941da177e4SLinus Torvalds 1995bcda7652SAl Viro /* O_PATH? */ 1996bcda7652SAl Viro if (!acc_mode) 1997bcda7652SAl Viro return 0; 1998bcda7652SAl Viro 19991da177e4SLinus Torvalds if (!inode) 20001da177e4SLinus Torvalds return -ENOENT; 20011da177e4SLinus Torvalds 2002c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2003c8fe8f30SChristoph Hellwig case S_IFLNK: 20041da177e4SLinus Torvalds return -ELOOP; 2005c8fe8f30SChristoph Hellwig case S_IFDIR: 2006c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 20071da177e4SLinus Torvalds return -EISDIR; 2008c8fe8f30SChristoph Hellwig break; 2009c8fe8f30SChristoph Hellwig case S_IFBLK: 2010c8fe8f30SChristoph Hellwig case S_IFCHR: 20113fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 20121da177e4SLinus Torvalds return -EACCES; 2013c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2014c8fe8f30SChristoph Hellwig case S_IFIFO: 2015c8fe8f30SChristoph Hellwig case S_IFSOCK: 20161da177e4SLinus Torvalds flag &= ~O_TRUNC; 2017c8fe8f30SChristoph Hellwig break; 20184a3fd211SDave Hansen } 2019b41572e9SDave Hansen 20203fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2021b41572e9SDave Hansen if (error) 2022b41572e9SDave Hansen return error; 20236146f0d5SMimi Zohar 20241da177e4SLinus Torvalds /* 20251da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 20261da177e4SLinus Torvalds */ 20271da177e4SLinus Torvalds if (IS_APPEND(inode)) { 20288737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 20297715b521SAl Viro return -EPERM; 20301da177e4SLinus Torvalds if (flag & O_TRUNC) 20317715b521SAl Viro return -EPERM; 20321da177e4SLinus Torvalds } 20331da177e4SLinus Torvalds 20341da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 20357715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 20367715b521SAl Viro return -EPERM; 20371da177e4SLinus Torvalds 20381da177e4SLinus Torvalds /* 20391da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 20401da177e4SLinus Torvalds */ 2041b65a9cfcSAl Viro return break_lease(inode, flag); 20427715b521SAl Viro } 20437715b521SAl Viro 2044e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20457715b521SAl Viro { 2046e1181ee6SJeff Layton struct path *path = &filp->f_path; 20477715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20487715b521SAl Viro int error = get_write_access(inode); 20491da177e4SLinus Torvalds if (error) 20507715b521SAl Viro return error; 20511da177e4SLinus Torvalds /* 20521da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20531da177e4SLinus Torvalds */ 20541da177e4SLinus Torvalds error = locks_verify_locked(inode); 2055be6d3e56SKentaro Takeda if (!error) 2056ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20571da177e4SLinus Torvalds if (!error) { 20587715b521SAl Viro error = do_truncate(path->dentry, 0, 2059d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2060e1181ee6SJeff Layton filp); 20611da177e4SLinus Torvalds } 20621da177e4SLinus Torvalds put_write_access(inode); 2063acd0c935SMimi Zohar return error; 20641da177e4SLinus Torvalds } 20651da177e4SLinus Torvalds 2066d57999e1SDave Hansen /* 2067d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2068d57999e1SDave Hansen * 00 - read-only 2069d57999e1SDave Hansen * 01 - write-only 2070d57999e1SDave Hansen * 10 - read-write 2071d57999e1SDave Hansen * 11 - special 2072d57999e1SDave Hansen * it is changed into 2073d57999e1SDave Hansen * 00 - no permissions needed 2074d57999e1SDave Hansen * 01 - read-permission 2075d57999e1SDave Hansen * 10 - write-permission 2076d57999e1SDave Hansen * 11 - read-write 2077d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2078d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2079d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2080d57999e1SDave Hansen * later). 2081d57999e1SDave Hansen * 2082d57999e1SDave Hansen */ 2083d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2084d57999e1SDave Hansen { 2085d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2086d57999e1SDave Hansen flag++; 2087d57999e1SDave Hansen return flag; 2088d57999e1SDave Hansen } 2089d57999e1SDave Hansen 209031e6b01fSNick Piggin /* 2091fe2d35ffSAl Viro * Handle the last step of open() 209231e6b01fSNick Piggin */ 2093fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2094c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2095fb1cc555SAl Viro { 2096a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20976c0d46c4SAl Viro struct dentry *dentry; 2098ca344a89SAl Viro int open_flag = op->open_flag; 20996c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2100ca344a89SAl Viro int want_write = 0; 2101bcda7652SAl Viro int acc_mode = op->acc_mode; 2102fb1cc555SAl Viro struct file *filp; 210316c2cd71SAl Viro int error; 2104fb1cc555SAl Viro 2105c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2106c3e380b0SAl Viro nd->flags |= op->intent; 2107c3e380b0SAl Viro 21081f36f774SAl Viro switch (nd->last_type) { 21091f36f774SAl Viro case LAST_DOTDOT: 2110176306f5SNeil Brown case LAST_DOT: 2111fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2112fe2d35ffSAl Viro if (error) 2113fe2d35ffSAl Viro return ERR_PTR(error); 21141f36f774SAl Viro /* fallthrough */ 21151f36f774SAl Viro case LAST_ROOT: 2116fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2117fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2118fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2119fe2d35ffSAl Viro } 212016c2cd71SAl Viro error = handle_reval_path(nd); 212116c2cd71SAl Viro if (error) 212216c2cd71SAl Viro goto exit; 2123fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2124ca344a89SAl Viro if (open_flag & O_CREAT) { 212516c2cd71SAl Viro error = -EISDIR; 21261f36f774SAl Viro goto exit; 2127fe2d35ffSAl Viro } 2128fe2d35ffSAl Viro goto ok; 21291f36f774SAl Viro case LAST_BIND: 2130fe2d35ffSAl Viro /* can't be RCU mode here */ 213116c2cd71SAl Viro error = handle_reval_path(nd); 213216c2cd71SAl Viro if (error) 213316c2cd71SAl Viro goto exit; 21341f36f774SAl Viro audit_inode(pathname, dir); 21351f36f774SAl Viro goto ok; 21361f36f774SAl Viro } 2137a2c36b45SAl Viro 2138ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2139bcda7652SAl Viro int symlink_ok = 0; 2140fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2141fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2142bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2143bcda7652SAl Viro symlink_ok = 1; 2144fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2145ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2146ce57dfc1SAl Viro !symlink_ok); 2147ce57dfc1SAl Viro if (error < 0) 2148fe2d35ffSAl Viro return ERR_PTR(error); 2149ce57dfc1SAl Viro if (error) /* symlink */ 2150fe2d35ffSAl Viro return NULL; 2151fe2d35ffSAl Viro /* sayonara */ 2152fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2153fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2154fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2155fe2d35ffSAl Viro } 2156fe2d35ffSAl Viro 2157fe2d35ffSAl Viro error = -ENOTDIR; 2158fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2159ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2160fe2d35ffSAl Viro goto exit; 2161fe2d35ffSAl Viro } 2162fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2163fe2d35ffSAl Viro goto ok; 2164fe2d35ffSAl Viro } 2165fe2d35ffSAl Viro 2166fe2d35ffSAl Viro /* create side of things */ 2167fe2d35ffSAl Viro 2168fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2169fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2170fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2171fe2d35ffSAl Viro } 2172fe2d35ffSAl Viro 2173fe2d35ffSAl Viro audit_inode(pathname, dir); 217416c2cd71SAl Viro error = -EISDIR; 21751f36f774SAl Viro /* trailing slashes? */ 217631e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21771f36f774SAl Viro goto exit; 21781f36f774SAl Viro 2179a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2180a1e28038SAl Viro 21816c0d46c4SAl Viro dentry = lookup_hash(nd); 21826c0d46c4SAl Viro error = PTR_ERR(dentry); 21836c0d46c4SAl Viro if (IS_ERR(dentry)) { 2184fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2185fb1cc555SAl Viro goto exit; 2186fb1cc555SAl Viro } 2187fb1cc555SAl Viro 21886c0d46c4SAl Viro path->dentry = dentry; 21896c0d46c4SAl Viro path->mnt = nd->path.mnt; 21906c0d46c4SAl Viro 2191fb1cc555SAl Viro /* Negative dentry, just create the file */ 21926c0d46c4SAl Viro if (!dentry->d_inode) { 21936c0d46c4SAl Viro int mode = op->mode; 21946c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21956c0d46c4SAl Viro mode &= ~current_umask(); 2196fb1cc555SAl Viro /* 2197fb1cc555SAl Viro * This write is needed to ensure that a 21986c0d46c4SAl Viro * rw->ro transition does not occur between 2199fb1cc555SAl Viro * the time when the file is created and when 2200fb1cc555SAl Viro * a permanent write count is taken through 2201fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2202fb1cc555SAl Viro */ 2203fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2204fb1cc555SAl Viro if (error) 2205fb1cc555SAl Viro goto exit_mutex_unlock; 2206ca344a89SAl Viro want_write = 1; 22079b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2208ca344a89SAl Viro open_flag &= ~O_TRUNC; 22096c0d46c4SAl Viro will_truncate = 0; 2210bcda7652SAl Viro acc_mode = MAY_OPEN; 22116c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 22126c0d46c4SAl Viro if (error) 22136c0d46c4SAl Viro goto exit_mutex_unlock; 22146c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 22156c0d46c4SAl Viro if (error) 22166c0d46c4SAl Viro goto exit_mutex_unlock; 22176c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 22186c0d46c4SAl Viro dput(nd->path.dentry); 22196c0d46c4SAl Viro nd->path.dentry = dentry; 2220ca344a89SAl Viro goto common; 2221fb1cc555SAl Viro } 2222fb1cc555SAl Viro 2223fb1cc555SAl Viro /* 2224fb1cc555SAl Viro * It already exists. 2225fb1cc555SAl Viro */ 2226fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2227fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2228fb1cc555SAl Viro 2229fb1cc555SAl Viro error = -EEXIST; 2230ca344a89SAl Viro if (open_flag & O_EXCL) 2231fb1cc555SAl Viro goto exit_dput; 2232fb1cc555SAl Viro 22339875cf80SDavid Howells error = follow_managed(path, nd->flags); 22349875cf80SDavid Howells if (error < 0) 2235fb1cc555SAl Viro goto exit_dput; 2236fb1cc555SAl Viro 2237fb1cc555SAl Viro error = -ENOENT; 2238fb1cc555SAl Viro if (!path->dentry->d_inode) 2239fb1cc555SAl Viro goto exit_dput; 22409e67f361SAl Viro 22419e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2242fb1cc555SAl Viro return NULL; 2243fb1cc555SAl Viro 2244fb1cc555SAl Viro path_to_nameidata(path, nd); 224531e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2246fb1cc555SAl Viro error = -EISDIR; 224731e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2248fb1cc555SAl Viro goto exit; 224967ee3ad2SAl Viro ok: 22506c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22516c0d46c4SAl Viro will_truncate = 0; 22526c0d46c4SAl Viro 22530f9d1a10SAl Viro if (will_truncate) { 22540f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22550f9d1a10SAl Viro if (error) 22560f9d1a10SAl Viro goto exit; 2257ca344a89SAl Viro want_write = 1; 22580f9d1a10SAl Viro } 2259ca344a89SAl Viro common: 2260bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2261ca344a89SAl Viro if (error) 22620f9d1a10SAl Viro goto exit; 22630f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22640f9d1a10SAl Viro if (!IS_ERR(filp)) { 22650f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22660f9d1a10SAl Viro if (error) { 22670f9d1a10SAl Viro fput(filp); 22680f9d1a10SAl Viro filp = ERR_PTR(error); 22690f9d1a10SAl Viro } 22700f9d1a10SAl Viro } 22710f9d1a10SAl Viro if (!IS_ERR(filp)) { 22720f9d1a10SAl Viro if (will_truncate) { 22730f9d1a10SAl Viro error = handle_truncate(filp); 22740f9d1a10SAl Viro if (error) { 22750f9d1a10SAl Viro fput(filp); 22760f9d1a10SAl Viro filp = ERR_PTR(error); 22770f9d1a10SAl Viro } 22780f9d1a10SAl Viro } 22790f9d1a10SAl Viro } 2280ca344a89SAl Viro out: 2281ca344a89SAl Viro if (want_write) 22820f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22830f9d1a10SAl Viro path_put(&nd->path); 2284fb1cc555SAl Viro return filp; 2285fb1cc555SAl Viro 2286fb1cc555SAl Viro exit_mutex_unlock: 2287fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2288fb1cc555SAl Viro exit_dput: 2289fb1cc555SAl Viro path_put_conditional(path, nd); 2290fb1cc555SAl Viro exit: 2291ca344a89SAl Viro filp = ERR_PTR(error); 2292ca344a89SAl Viro goto out; 2293fb1cc555SAl Viro } 2294fb1cc555SAl Viro 229513aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 229673d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22971da177e4SLinus Torvalds { 2298fe2d35ffSAl Viro struct file *base = NULL; 22994a3fd211SDave Hansen struct file *filp; 23009850c056SAl Viro struct path path; 23011da177e4SLinus Torvalds int count = 0; 230213aab428SAl Viro int error; 230331e6b01fSNick Piggin 230431e6b01fSNick Piggin filp = get_empty_filp(); 230531e6b01fSNick Piggin if (!filp) 230631e6b01fSNick Piggin return ERR_PTR(-ENFILE); 230731e6b01fSNick Piggin 230847c805dcSAl Viro filp->f_flags = op->open_flag; 230973d049a4SAl Viro nd->intent.open.file = filp; 231073d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 231173d049a4SAl Viro nd->intent.open.create_mode = op->mode; 231231e6b01fSNick Piggin 231373d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 231431e6b01fSNick Piggin if (unlikely(error)) 231513aab428SAl Viro goto out_filp; 231631e6b01fSNick Piggin 2317fe2d35ffSAl Viro current->total_link_count = 0; 231873d049a4SAl Viro error = link_path_walk(pathname, nd); 231931e6b01fSNick Piggin if (unlikely(error)) 232031e6b01fSNick Piggin goto out_filp; 23211da177e4SLinus Torvalds 232273d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2323806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 23247b9337aaSNick Piggin struct path link = path; 23257b9337aaSNick Piggin struct inode *linki = link.dentry->d_inode; 2326def4af30SAl Viro void *cookie; 232773d049a4SAl Viro if (!(nd->flags & LOOKUP_FOLLOW) || count++ == 32) { 232873d049a4SAl Viro path_put_conditional(&path, nd); 232973d049a4SAl Viro path_put(&nd->path); 233040b39136SAl Viro filp = ERR_PTR(-ELOOP); 233140b39136SAl Viro break; 233240b39136SAl Viro } 2333806b681cSAl Viro /* 2334806b681cSAl Viro * This is subtle. Instead of calling do_follow_link() we do 2335806b681cSAl Viro * the thing by hands. The reason is that this way we have zero 2336806b681cSAl Viro * link_count and path_walk() (called from ->follow_link) 2337806b681cSAl Viro * honoring LOOKUP_PARENT. After that we have the parent and 2338806b681cSAl Viro * last component, i.e. we are in the same situation as after 2339806b681cSAl Viro * the first path_walk(). Well, almost - if the last component 2340806b681cSAl Viro * is normal we get its copy stored in nd->last.name and we will 2341806b681cSAl Viro * have to putname() it when we are done. Procfs-like symlinks 2342806b681cSAl Viro * just set LAST_BIND. 2343806b681cSAl Viro */ 234473d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 234573d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 234673d049a4SAl Viro error = __do_follow_link(&link, nd, &cookie); 2347c3e380b0SAl Viro if (unlikely(error)) 2348f1afe9efSAl Viro filp = ERR_PTR(error); 2349c3e380b0SAl Viro else 235073d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2351f1afe9efSAl Viro if (!IS_ERR(cookie) && linki->i_op->put_link) 235273d049a4SAl Viro linki->i_op->put_link(link.dentry, nd, cookie); 23537b9337aaSNick Piggin path_put(&link); 2354806b681cSAl Viro } 235510fa8e62SAl Viro out: 235673d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 235773d049a4SAl Viro path_put(&nd->root); 2358fe2d35ffSAl Viro if (base) 2359fe2d35ffSAl Viro fput(base); 236073d049a4SAl Viro release_open_intent(nd); 236110fa8e62SAl Viro return filp; 23621da177e4SLinus Torvalds 236331e6b01fSNick Piggin out_filp: 236410fa8e62SAl Viro filp = ERR_PTR(error); 236510fa8e62SAl Viro goto out; 2366de459215SKirill Korotaev } 23671da177e4SLinus Torvalds 236813aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 236913aab428SAl Viro const struct open_flags *op, int flags) 237013aab428SAl Viro { 237173d049a4SAl Viro struct nameidata nd; 237213aab428SAl Viro struct file *filp; 237313aab428SAl Viro 237473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 237513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 237673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 237713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 237873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 237913aab428SAl Viro return filp; 238013aab428SAl Viro } 238113aab428SAl Viro 238273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 238373d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 238473d049a4SAl Viro { 238573d049a4SAl Viro struct nameidata nd; 238673d049a4SAl Viro struct file *file; 238773d049a4SAl Viro 238873d049a4SAl Viro nd.root.mnt = mnt; 238973d049a4SAl Viro nd.root.dentry = dentry; 239073d049a4SAl Viro 239173d049a4SAl Viro flags |= LOOKUP_ROOT; 239273d049a4SAl Viro 2393bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 239473d049a4SAl Viro return ERR_PTR(-ELOOP); 239573d049a4SAl Viro 239673d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 239773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 239873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 239973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 240073d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 240173d049a4SAl Viro return file; 240273d049a4SAl Viro } 240373d049a4SAl Viro 24041da177e4SLinus Torvalds /** 24051da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 24061da177e4SLinus Torvalds * @nd: nameidata info 24071da177e4SLinus Torvalds * @is_dir: directory flag 24081da177e4SLinus Torvalds * 24091da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 24101da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2411c663e5d8SChristoph Hellwig * 24124ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 24131da177e4SLinus Torvalds */ 24141da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 24151da177e4SLinus Torvalds { 2416c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 24171da177e4SLinus Torvalds 24184ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2419c663e5d8SChristoph Hellwig /* 2420c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2421c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2422c663e5d8SChristoph Hellwig */ 24231da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 24241da177e4SLinus Torvalds goto fail; 24251da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 24263516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2427a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2428c663e5d8SChristoph Hellwig 2429c663e5d8SChristoph Hellwig /* 2430c663e5d8SChristoph Hellwig * Do the final lookup. 2431c663e5d8SChristoph Hellwig */ 243249705b77SChristoph Hellwig dentry = lookup_hash(nd); 24331da177e4SLinus Torvalds if (IS_ERR(dentry)) 24341da177e4SLinus Torvalds goto fail; 2435c663e5d8SChristoph Hellwig 2436e9baf6e5SAl Viro if (dentry->d_inode) 2437e9baf6e5SAl Viro goto eexist; 2438c663e5d8SChristoph Hellwig /* 2439c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2440c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2441c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2442c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2443c663e5d8SChristoph Hellwig */ 2444e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 24451da177e4SLinus Torvalds dput(dentry); 24461da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2447e9baf6e5SAl Viro } 2448e9baf6e5SAl Viro return dentry; 2449e9baf6e5SAl Viro eexist: 2450e9baf6e5SAl Viro dput(dentry); 2451e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 24521da177e4SLinus Torvalds fail: 24531da177e4SLinus Torvalds return dentry; 24541da177e4SLinus Torvalds } 2455f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 24561da177e4SLinus Torvalds 24571da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24581da177e4SLinus Torvalds { 2459a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24601da177e4SLinus Torvalds 24611da177e4SLinus Torvalds if (error) 24621da177e4SLinus Torvalds return error; 24631da177e4SLinus Torvalds 24641da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 24651da177e4SLinus Torvalds return -EPERM; 24661da177e4SLinus Torvalds 2467acfa4380SAl Viro if (!dir->i_op->mknod) 24681da177e4SLinus Torvalds return -EPERM; 24691da177e4SLinus Torvalds 247008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 247108ce5f16SSerge E. Hallyn if (error) 247208ce5f16SSerge E. Hallyn return error; 247308ce5f16SSerge E. Hallyn 24741da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24751da177e4SLinus Torvalds if (error) 24761da177e4SLinus Torvalds return error; 24771da177e4SLinus Torvalds 24781da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2479a74574aaSStephen Smalley if (!error) 2480f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24811da177e4SLinus Torvalds return error; 24821da177e4SLinus Torvalds } 24831da177e4SLinus Torvalds 2484463c3197SDave Hansen static int may_mknod(mode_t mode) 2485463c3197SDave Hansen { 2486463c3197SDave Hansen switch (mode & S_IFMT) { 2487463c3197SDave Hansen case S_IFREG: 2488463c3197SDave Hansen case S_IFCHR: 2489463c3197SDave Hansen case S_IFBLK: 2490463c3197SDave Hansen case S_IFIFO: 2491463c3197SDave Hansen case S_IFSOCK: 2492463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2493463c3197SDave Hansen return 0; 2494463c3197SDave Hansen case S_IFDIR: 2495463c3197SDave Hansen return -EPERM; 2496463c3197SDave Hansen default: 2497463c3197SDave Hansen return -EINVAL; 2498463c3197SDave Hansen } 2499463c3197SDave Hansen } 2500463c3197SDave Hansen 25012e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 25022e4d0924SHeiko Carstens unsigned, dev) 25031da177e4SLinus Torvalds { 25042ad94ae6SAl Viro int error; 25051da177e4SLinus Torvalds char *tmp; 25061da177e4SLinus Torvalds struct dentry *dentry; 25071da177e4SLinus Torvalds struct nameidata nd; 25081da177e4SLinus Torvalds 25091da177e4SLinus Torvalds if (S_ISDIR(mode)) 25101da177e4SLinus Torvalds return -EPERM; 25111da177e4SLinus Torvalds 25122ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 25131da177e4SLinus Torvalds if (error) 25142ad94ae6SAl Viro return error; 25152ad94ae6SAl Viro 25161da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2517463c3197SDave Hansen if (IS_ERR(dentry)) { 25181da177e4SLinus Torvalds error = PTR_ERR(dentry); 2519463c3197SDave Hansen goto out_unlock; 2520463c3197SDave Hansen } 25214ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2522ce3b0f8dSAl Viro mode &= ~current_umask(); 2523463c3197SDave Hansen error = may_mknod(mode); 2524463c3197SDave Hansen if (error) 2525463c3197SDave Hansen goto out_dput; 2526463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2527463c3197SDave Hansen if (error) 2528463c3197SDave Hansen goto out_dput; 2529be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2530be6d3e56SKentaro Takeda if (error) 2531be6d3e56SKentaro Takeda goto out_drop_write; 25321da177e4SLinus Torvalds switch (mode & S_IFMT) { 25331da177e4SLinus Torvalds case 0: case S_IFREG: 25344ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 25351da177e4SLinus Torvalds break; 25361da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 25374ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 25381da177e4SLinus Torvalds new_decode_dev(dev)); 25391da177e4SLinus Torvalds break; 25401da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 25414ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 25421da177e4SLinus Torvalds break; 25431da177e4SLinus Torvalds } 2544be6d3e56SKentaro Takeda out_drop_write: 2545463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2546463c3197SDave Hansen out_dput: 25471da177e4SLinus Torvalds dput(dentry); 2548463c3197SDave Hansen out_unlock: 25494ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25501d957f9bSJan Blunck path_put(&nd.path); 25511da177e4SLinus Torvalds putname(tmp); 25521da177e4SLinus Torvalds 25531da177e4SLinus Torvalds return error; 25541da177e4SLinus Torvalds } 25551da177e4SLinus Torvalds 25563480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25575590ff0dSUlrich Drepper { 25585590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25595590ff0dSUlrich Drepper } 25605590ff0dSUlrich Drepper 25611da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25621da177e4SLinus Torvalds { 2563a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25641da177e4SLinus Torvalds 25651da177e4SLinus Torvalds if (error) 25661da177e4SLinus Torvalds return error; 25671da177e4SLinus Torvalds 2568acfa4380SAl Viro if (!dir->i_op->mkdir) 25691da177e4SLinus Torvalds return -EPERM; 25701da177e4SLinus Torvalds 25711da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25721da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25731da177e4SLinus Torvalds if (error) 25741da177e4SLinus Torvalds return error; 25751da177e4SLinus Torvalds 25761da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2577a74574aaSStephen Smalley if (!error) 2578f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25791da177e4SLinus Torvalds return error; 25801da177e4SLinus Torvalds } 25811da177e4SLinus Torvalds 25822e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25831da177e4SLinus Torvalds { 25841da177e4SLinus Torvalds int error = 0; 25851da177e4SLinus Torvalds char * tmp; 25866902d925SDave Hansen struct dentry *dentry; 25876902d925SDave Hansen struct nameidata nd; 25881da177e4SLinus Torvalds 25892ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25902ad94ae6SAl Viro if (error) 25916902d925SDave Hansen goto out_err; 25921da177e4SLinus Torvalds 25931da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25941da177e4SLinus Torvalds error = PTR_ERR(dentry); 25956902d925SDave Hansen if (IS_ERR(dentry)) 25966902d925SDave Hansen goto out_unlock; 25976902d925SDave Hansen 25984ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2599ce3b0f8dSAl Viro mode &= ~current_umask(); 2600463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2601463c3197SDave Hansen if (error) 2602463c3197SDave Hansen goto out_dput; 2603be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2604be6d3e56SKentaro Takeda if (error) 2605be6d3e56SKentaro Takeda goto out_drop_write; 26064ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2607be6d3e56SKentaro Takeda out_drop_write: 2608463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2609463c3197SDave Hansen out_dput: 26101da177e4SLinus Torvalds dput(dentry); 26116902d925SDave Hansen out_unlock: 26124ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26131d957f9bSJan Blunck path_put(&nd.path); 26141da177e4SLinus Torvalds putname(tmp); 26156902d925SDave Hansen out_err: 26161da177e4SLinus Torvalds return error; 26171da177e4SLinus Torvalds } 26181da177e4SLinus Torvalds 26193cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 26205590ff0dSUlrich Drepper { 26215590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 26225590ff0dSUlrich Drepper } 26235590ff0dSUlrich Drepper 26241da177e4SLinus Torvalds /* 26251da177e4SLinus Torvalds * We try to drop the dentry early: we should have 26261da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 26271da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 26281da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 26291da177e4SLinus Torvalds * 26301da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 26311da177e4SLinus Torvalds * do a 26321da177e4SLinus Torvalds * 26331da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 26341da177e4SLinus Torvalds * return -EBUSY; 26351da177e4SLinus Torvalds * 26361da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 26371da177e4SLinus Torvalds * that is still in use by something else.. 26381da177e4SLinus Torvalds */ 26391da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 26401da177e4SLinus Torvalds { 26411da177e4SLinus Torvalds dget(dentry); 26421da177e4SLinus Torvalds shrink_dcache_parent(dentry); 26431da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2644b7ab39f6SNick Piggin if (dentry->d_count == 2) 26451da177e4SLinus Torvalds __d_drop(dentry); 26461da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 26471da177e4SLinus Torvalds } 26481da177e4SLinus Torvalds 26491da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 26501da177e4SLinus Torvalds { 26511da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26521da177e4SLinus Torvalds 26531da177e4SLinus Torvalds if (error) 26541da177e4SLinus Torvalds return error; 26551da177e4SLinus Torvalds 2656acfa4380SAl Viro if (!dir->i_op->rmdir) 26571da177e4SLinus Torvalds return -EPERM; 26581da177e4SLinus Torvalds 26591b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26601da177e4SLinus Torvalds dentry_unhash(dentry); 26611da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26621da177e4SLinus Torvalds error = -EBUSY; 26631da177e4SLinus Torvalds else { 26641da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 26651da177e4SLinus Torvalds if (!error) { 26661da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2667d83c49f3SAl Viro if (!error) { 26681da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2669d83c49f3SAl Viro dont_mount(dentry); 2670d83c49f3SAl Viro } 26711da177e4SLinus Torvalds } 26721da177e4SLinus Torvalds } 26731b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26741da177e4SLinus Torvalds if (!error) { 26751da177e4SLinus Torvalds d_delete(dentry); 26761da177e4SLinus Torvalds } 26771da177e4SLinus Torvalds dput(dentry); 26781da177e4SLinus Torvalds 26791da177e4SLinus Torvalds return error; 26801da177e4SLinus Torvalds } 26811da177e4SLinus Torvalds 26825590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26831da177e4SLinus Torvalds { 26841da177e4SLinus Torvalds int error = 0; 26851da177e4SLinus Torvalds char * name; 26861da177e4SLinus Torvalds struct dentry *dentry; 26871da177e4SLinus Torvalds struct nameidata nd; 26881da177e4SLinus Torvalds 26892ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26901da177e4SLinus Torvalds if (error) 26912ad94ae6SAl Viro return error; 26921da177e4SLinus Torvalds 26931da177e4SLinus Torvalds switch(nd.last_type) { 26941da177e4SLinus Torvalds case LAST_DOTDOT: 26951da177e4SLinus Torvalds error = -ENOTEMPTY; 26961da177e4SLinus Torvalds goto exit1; 26971da177e4SLinus Torvalds case LAST_DOT: 26981da177e4SLinus Torvalds error = -EINVAL; 26991da177e4SLinus Torvalds goto exit1; 27001da177e4SLinus Torvalds case LAST_ROOT: 27011da177e4SLinus Torvalds error = -EBUSY; 27021da177e4SLinus Torvalds goto exit1; 27031da177e4SLinus Torvalds } 27040612d9fbSOGAWA Hirofumi 27050612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27060612d9fbSOGAWA Hirofumi 27074ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 270849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27091da177e4SLinus Torvalds error = PTR_ERR(dentry); 27106902d925SDave Hansen if (IS_ERR(dentry)) 27116902d925SDave Hansen goto exit2; 27120622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27130622753bSDave Hansen if (error) 27140622753bSDave Hansen goto exit3; 2715be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2716be6d3e56SKentaro Takeda if (error) 2717be6d3e56SKentaro Takeda goto exit4; 27184ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2719be6d3e56SKentaro Takeda exit4: 27200622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27210622753bSDave Hansen exit3: 27221da177e4SLinus Torvalds dput(dentry); 27236902d925SDave Hansen exit2: 27244ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27251da177e4SLinus Torvalds exit1: 27261d957f9bSJan Blunck path_put(&nd.path); 27271da177e4SLinus Torvalds putname(name); 27281da177e4SLinus Torvalds return error; 27291da177e4SLinus Torvalds } 27301da177e4SLinus Torvalds 27313cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 27325590ff0dSUlrich Drepper { 27335590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 27345590ff0dSUlrich Drepper } 27355590ff0dSUlrich Drepper 27361da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 27371da177e4SLinus Torvalds { 27381da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 27391da177e4SLinus Torvalds 27401da177e4SLinus Torvalds if (error) 27411da177e4SLinus Torvalds return error; 27421da177e4SLinus Torvalds 2743acfa4380SAl Viro if (!dir->i_op->unlink) 27441da177e4SLinus Torvalds return -EPERM; 27451da177e4SLinus Torvalds 27461b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 27471da177e4SLinus Torvalds if (d_mountpoint(dentry)) 27481da177e4SLinus Torvalds error = -EBUSY; 27491da177e4SLinus Torvalds else { 27501da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2751bec1052eSAl Viro if (!error) { 27521da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2753bec1052eSAl Viro if (!error) 2754d83c49f3SAl Viro dont_mount(dentry); 2755bec1052eSAl Viro } 27561da177e4SLinus Torvalds } 27571b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27581da177e4SLinus Torvalds 27591da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27601da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2761ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27621da177e4SLinus Torvalds d_delete(dentry); 27631da177e4SLinus Torvalds } 27640eeca283SRobert Love 27651da177e4SLinus Torvalds return error; 27661da177e4SLinus Torvalds } 27671da177e4SLinus Torvalds 27681da177e4SLinus Torvalds /* 27691da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27701b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27711da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27721da177e4SLinus Torvalds * while waiting on the I/O. 27731da177e4SLinus Torvalds */ 27745590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27751da177e4SLinus Torvalds { 27762ad94ae6SAl Viro int error; 27771da177e4SLinus Torvalds char *name; 27781da177e4SLinus Torvalds struct dentry *dentry; 27791da177e4SLinus Torvalds struct nameidata nd; 27801da177e4SLinus Torvalds struct inode *inode = NULL; 27811da177e4SLinus Torvalds 27822ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27831da177e4SLinus Torvalds if (error) 27842ad94ae6SAl Viro return error; 27852ad94ae6SAl Viro 27861da177e4SLinus Torvalds error = -EISDIR; 27871da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27881da177e4SLinus Torvalds goto exit1; 27890612d9fbSOGAWA Hirofumi 27900612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27910612d9fbSOGAWA Hirofumi 27924ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 279349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27941da177e4SLinus Torvalds error = PTR_ERR(dentry); 27951da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27961da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 27971da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 27981da177e4SLinus Torvalds goto slashes; 27991da177e4SLinus Torvalds inode = dentry->d_inode; 28001da177e4SLinus Torvalds if (inode) 28017de9c6eeSAl Viro ihold(inode); 28020622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 28030622753bSDave Hansen if (error) 28040622753bSDave Hansen goto exit2; 2805be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2806be6d3e56SKentaro Takeda if (error) 2807be6d3e56SKentaro Takeda goto exit3; 28084ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2809be6d3e56SKentaro Takeda exit3: 28100622753bSDave Hansen mnt_drop_write(nd.path.mnt); 28111da177e4SLinus Torvalds exit2: 28121da177e4SLinus Torvalds dput(dentry); 28131da177e4SLinus Torvalds } 28144ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28151da177e4SLinus Torvalds if (inode) 28161da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 28171da177e4SLinus Torvalds exit1: 28181d957f9bSJan Blunck path_put(&nd.path); 28191da177e4SLinus Torvalds putname(name); 28201da177e4SLinus Torvalds return error; 28211da177e4SLinus Torvalds 28221da177e4SLinus Torvalds slashes: 28231da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 28241da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 28251da177e4SLinus Torvalds goto exit2; 28261da177e4SLinus Torvalds } 28271da177e4SLinus Torvalds 28282e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 28295590ff0dSUlrich Drepper { 28305590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 28315590ff0dSUlrich Drepper return -EINVAL; 28325590ff0dSUlrich Drepper 28335590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 28345590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 28355590ff0dSUlrich Drepper 28365590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 28375590ff0dSUlrich Drepper } 28385590ff0dSUlrich Drepper 28393480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 28405590ff0dSUlrich Drepper { 28415590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 28425590ff0dSUlrich Drepper } 28435590ff0dSUlrich Drepper 2844db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 28451da177e4SLinus Torvalds { 2846a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28471da177e4SLinus Torvalds 28481da177e4SLinus Torvalds if (error) 28491da177e4SLinus Torvalds return error; 28501da177e4SLinus Torvalds 2851acfa4380SAl Viro if (!dir->i_op->symlink) 28521da177e4SLinus Torvalds return -EPERM; 28531da177e4SLinus Torvalds 28541da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28551da177e4SLinus Torvalds if (error) 28561da177e4SLinus Torvalds return error; 28571da177e4SLinus Torvalds 28581da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2859a74574aaSStephen Smalley if (!error) 2860f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28611da177e4SLinus Torvalds return error; 28621da177e4SLinus Torvalds } 28631da177e4SLinus Torvalds 28642e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28652e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28661da177e4SLinus Torvalds { 28672ad94ae6SAl Viro int error; 28681da177e4SLinus Torvalds char *from; 28691da177e4SLinus Torvalds char *to; 28706902d925SDave Hansen struct dentry *dentry; 28716902d925SDave Hansen struct nameidata nd; 28721da177e4SLinus Torvalds 28731da177e4SLinus Torvalds from = getname(oldname); 28741da177e4SLinus Torvalds if (IS_ERR(from)) 28751da177e4SLinus Torvalds return PTR_ERR(from); 28762ad94ae6SAl Viro 28772ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28782ad94ae6SAl Viro if (error) 28796902d925SDave Hansen goto out_putname; 28801da177e4SLinus Torvalds 28811da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28821da177e4SLinus Torvalds error = PTR_ERR(dentry); 28836902d925SDave Hansen if (IS_ERR(dentry)) 28846902d925SDave Hansen goto out_unlock; 28856902d925SDave Hansen 288675c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 288775c3f29dSDave Hansen if (error) 288875c3f29dSDave Hansen goto out_dput; 2889be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2890be6d3e56SKentaro Takeda if (error) 2891be6d3e56SKentaro Takeda goto out_drop_write; 2892db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2893be6d3e56SKentaro Takeda out_drop_write: 289475c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 289575c3f29dSDave Hansen out_dput: 28961da177e4SLinus Torvalds dput(dentry); 28976902d925SDave Hansen out_unlock: 28984ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28991d957f9bSJan Blunck path_put(&nd.path); 29001da177e4SLinus Torvalds putname(to); 29016902d925SDave Hansen out_putname: 29021da177e4SLinus Torvalds putname(from); 29031da177e4SLinus Torvalds return error; 29041da177e4SLinus Torvalds } 29051da177e4SLinus Torvalds 29063480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 29075590ff0dSUlrich Drepper { 29085590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 29095590ff0dSUlrich Drepper } 29105590ff0dSUlrich Drepper 29111da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 29121da177e4SLinus Torvalds { 29131da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 29141da177e4SLinus Torvalds int error; 29151da177e4SLinus Torvalds 29161da177e4SLinus Torvalds if (!inode) 29171da177e4SLinus Torvalds return -ENOENT; 29181da177e4SLinus Torvalds 2919a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 29201da177e4SLinus Torvalds if (error) 29211da177e4SLinus Torvalds return error; 29221da177e4SLinus Torvalds 29231da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 29241da177e4SLinus Torvalds return -EXDEV; 29251da177e4SLinus Torvalds 29261da177e4SLinus Torvalds /* 29271da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 29281da177e4SLinus Torvalds */ 29291da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 29301da177e4SLinus Torvalds return -EPERM; 2931acfa4380SAl Viro if (!dir->i_op->link) 29321da177e4SLinus Torvalds return -EPERM; 29337e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 29341da177e4SLinus Torvalds return -EPERM; 29351da177e4SLinus Torvalds 29361da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 29371da177e4SLinus Torvalds if (error) 29381da177e4SLinus Torvalds return error; 29391da177e4SLinus Torvalds 29407e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2941aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2942aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2943aae8a97dSAneesh Kumar K.V error = -ENOENT; 2944aae8a97dSAneesh Kumar K.V else 29451da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 29467e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2947e31e14ecSStephen Smalley if (!error) 29487e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 29491da177e4SLinus Torvalds return error; 29501da177e4SLinus Torvalds } 29511da177e4SLinus Torvalds 29521da177e4SLinus Torvalds /* 29531da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29541da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29551da177e4SLinus Torvalds * newname. --KAB 29561da177e4SLinus Torvalds * 29571da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29581da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29591da177e4SLinus Torvalds * and other special files. --ADM 29601da177e4SLinus Torvalds */ 29612e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29622e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29631da177e4SLinus Torvalds { 29641da177e4SLinus Torvalds struct dentry *new_dentry; 29652d8f3038SAl Viro struct nameidata nd; 29662d8f3038SAl Viro struct path old_path; 296711a7b371SAneesh Kumar K.V int how = 0; 29681da177e4SLinus Torvalds int error; 29691da177e4SLinus Torvalds char *to; 29701da177e4SLinus Torvalds 297111a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2972c04030e1SUlrich Drepper return -EINVAL; 297311a7b371SAneesh Kumar K.V /* 297411a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 297511a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 297611a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 297711a7b371SAneesh Kumar K.V */ 297811a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 297911a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 298011a7b371SAneesh Kumar K.V return -ENOENT; 298111a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 298211a7b371SAneesh Kumar K.V } 2983c04030e1SUlrich Drepper 298411a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 298511a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 298611a7b371SAneesh Kumar K.V 298711a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29881da177e4SLinus Torvalds if (error) 29892ad94ae6SAl Viro return error; 29902ad94ae6SAl Viro 29912ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29921da177e4SLinus Torvalds if (error) 29931da177e4SLinus Torvalds goto out; 29941da177e4SLinus Torvalds error = -EXDEV; 29952d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29961da177e4SLinus Torvalds goto out_release; 29971da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29981da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29996902d925SDave Hansen if (IS_ERR(new_dentry)) 30006902d925SDave Hansen goto out_unlock; 300175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 300275c3f29dSDave Hansen if (error) 300375c3f29dSDave Hansen goto out_dput; 3004be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 3005be6d3e56SKentaro Takeda if (error) 3006be6d3e56SKentaro Takeda goto out_drop_write; 30072d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 3008be6d3e56SKentaro Takeda out_drop_write: 300975c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 301075c3f29dSDave Hansen out_dput: 30111da177e4SLinus Torvalds dput(new_dentry); 30126902d925SDave Hansen out_unlock: 30134ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 30141da177e4SLinus Torvalds out_release: 30151d957f9bSJan Blunck path_put(&nd.path); 30162ad94ae6SAl Viro putname(to); 30171da177e4SLinus Torvalds out: 30182d8f3038SAl Viro path_put(&old_path); 30191da177e4SLinus Torvalds 30201da177e4SLinus Torvalds return error; 30211da177e4SLinus Torvalds } 30221da177e4SLinus Torvalds 30233480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 30245590ff0dSUlrich Drepper { 3025c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 30265590ff0dSUlrich Drepper } 30275590ff0dSUlrich Drepper 30281da177e4SLinus Torvalds /* 30291da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 30301da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 30311da177e4SLinus Torvalds * Problems: 30321da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 30331da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 30341da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3035a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 30361da177e4SLinus Torvalds * story. 30371da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 30381b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 30391da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 30401da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3041a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 30421da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 30431da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 30441da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3045a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 30461da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 30471da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 30481da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 30491da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 30501da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 30511da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 30521da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 30531da177e4SLinus Torvalds * trick as in rmdir(). 30541da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 30551b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 30561da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3057c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 30581da177e4SLinus Torvalds * locking]. 30591da177e4SLinus Torvalds */ 306075c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30611da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30621da177e4SLinus Torvalds { 30631da177e4SLinus Torvalds int error = 0; 30641da177e4SLinus Torvalds struct inode *target; 30651da177e4SLinus Torvalds 30661da177e4SLinus Torvalds /* 30671da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30681da177e4SLinus Torvalds * we'll need to flip '..'. 30691da177e4SLinus Torvalds */ 30701da177e4SLinus Torvalds if (new_dir != old_dir) { 3071f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30721da177e4SLinus Torvalds if (error) 30731da177e4SLinus Torvalds return error; 30741da177e4SLinus Torvalds } 30751da177e4SLinus Torvalds 30761da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30771da177e4SLinus Torvalds if (error) 30781da177e4SLinus Torvalds return error; 30791da177e4SLinus Torvalds 30801da177e4SLinus Torvalds target = new_dentry->d_inode; 3081d83c49f3SAl Viro if (target) 30821b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30831da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30841da177e4SLinus Torvalds error = -EBUSY; 3085d83c49f3SAl Viro else { 3086d83c49f3SAl Viro if (target) 3087d83c49f3SAl Viro dentry_unhash(new_dentry); 30881da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3089d83c49f3SAl Viro } 30901da177e4SLinus Torvalds if (target) { 3091d83c49f3SAl Viro if (!error) { 30921da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3093d83c49f3SAl Viro dont_mount(new_dentry); 3094d83c49f3SAl Viro } 30951b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30961da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 30971da177e4SLinus Torvalds d_rehash(new_dentry); 30981da177e4SLinus Torvalds dput(new_dentry); 30991da177e4SLinus Torvalds } 3100e31e14ecSStephen Smalley if (!error) 3101349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 31021da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 31031da177e4SLinus Torvalds return error; 31041da177e4SLinus Torvalds } 31051da177e4SLinus Torvalds 310675c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 31071da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31081da177e4SLinus Torvalds { 31091da177e4SLinus Torvalds struct inode *target; 31101da177e4SLinus Torvalds int error; 31111da177e4SLinus Torvalds 31121da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 31131da177e4SLinus Torvalds if (error) 31141da177e4SLinus Torvalds return error; 31151da177e4SLinus Torvalds 31161da177e4SLinus Torvalds dget(new_dentry); 31171da177e4SLinus Torvalds target = new_dentry->d_inode; 31181da177e4SLinus Torvalds if (target) 31191b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 31201da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 31211da177e4SLinus Torvalds error = -EBUSY; 31221da177e4SLinus Torvalds else 31231da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 31241da177e4SLinus Torvalds if (!error) { 3125bec1052eSAl Viro if (target) 3126d83c49f3SAl Viro dont_mount(new_dentry); 3127349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 31281da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 31291da177e4SLinus Torvalds } 31301da177e4SLinus Torvalds if (target) 31311b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 31321da177e4SLinus Torvalds dput(new_dentry); 31331da177e4SLinus Torvalds return error; 31341da177e4SLinus Torvalds } 31351da177e4SLinus Torvalds 31361da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 31371da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31381da177e4SLinus Torvalds { 31391da177e4SLinus Torvalds int error; 31401da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 314159b0df21SEric Paris const unsigned char *old_name; 31421da177e4SLinus Torvalds 31431da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 31441da177e4SLinus Torvalds return 0; 31451da177e4SLinus Torvalds 31461da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 31471da177e4SLinus Torvalds if (error) 31481da177e4SLinus Torvalds return error; 31491da177e4SLinus Torvalds 31501da177e4SLinus Torvalds if (!new_dentry->d_inode) 3151a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 31521da177e4SLinus Torvalds else 31531da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31541da177e4SLinus Torvalds if (error) 31551da177e4SLinus Torvalds return error; 31561da177e4SLinus Torvalds 3157acfa4380SAl Viro if (!old_dir->i_op->rename) 31581da177e4SLinus Torvalds return -EPERM; 31591da177e4SLinus Torvalds 31600eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31610eeca283SRobert Love 31621da177e4SLinus Torvalds if (is_dir) 31631da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31641da177e4SLinus Torvalds else 31651da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3166123df294SAl Viro if (!error) 3167123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31685a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31690eeca283SRobert Love fsnotify_oldname_free(old_name); 31700eeca283SRobert Love 31711da177e4SLinus Torvalds return error; 31721da177e4SLinus Torvalds } 31731da177e4SLinus Torvalds 31742e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31752e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31761da177e4SLinus Torvalds { 31771da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31781da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31791da177e4SLinus Torvalds struct dentry *trap; 31801da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31812ad94ae6SAl Viro char *from; 31822ad94ae6SAl Viro char *to; 31832ad94ae6SAl Viro int error; 31841da177e4SLinus Torvalds 31852ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31861da177e4SLinus Torvalds if (error) 31871da177e4SLinus Torvalds goto exit; 31881da177e4SLinus Torvalds 31892ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31901da177e4SLinus Torvalds if (error) 31911da177e4SLinus Torvalds goto exit1; 31921da177e4SLinus Torvalds 31931da177e4SLinus Torvalds error = -EXDEV; 31944ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31951da177e4SLinus Torvalds goto exit2; 31961da177e4SLinus Torvalds 31974ac91378SJan Blunck old_dir = oldnd.path.dentry; 31981da177e4SLinus Torvalds error = -EBUSY; 31991da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 32001da177e4SLinus Torvalds goto exit2; 32011da177e4SLinus Torvalds 32024ac91378SJan Blunck new_dir = newnd.path.dentry; 32031da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 32041da177e4SLinus Torvalds goto exit2; 32051da177e4SLinus Torvalds 32060612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 32070612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 32084e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 32090612d9fbSOGAWA Hirofumi 32101da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 32111da177e4SLinus Torvalds 321249705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 32131da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 32141da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 32151da177e4SLinus Torvalds goto exit3; 32161da177e4SLinus Torvalds /* source must exist */ 32171da177e4SLinus Torvalds error = -ENOENT; 32181da177e4SLinus Torvalds if (!old_dentry->d_inode) 32191da177e4SLinus Torvalds goto exit4; 32201da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 32211da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 32221da177e4SLinus Torvalds error = -ENOTDIR; 32231da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 32241da177e4SLinus Torvalds goto exit4; 32251da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 32261da177e4SLinus Torvalds goto exit4; 32271da177e4SLinus Torvalds } 32281da177e4SLinus Torvalds /* source should not be ancestor of target */ 32291da177e4SLinus Torvalds error = -EINVAL; 32301da177e4SLinus Torvalds if (old_dentry == trap) 32311da177e4SLinus Torvalds goto exit4; 323249705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 32331da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 32341da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 32351da177e4SLinus Torvalds goto exit4; 32361da177e4SLinus Torvalds /* target should not be an ancestor of source */ 32371da177e4SLinus Torvalds error = -ENOTEMPTY; 32381da177e4SLinus Torvalds if (new_dentry == trap) 32391da177e4SLinus Torvalds goto exit5; 32401da177e4SLinus Torvalds 32419079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 32429079b1ebSDave Hansen if (error) 32439079b1ebSDave Hansen goto exit5; 3244be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3245be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3246be6d3e56SKentaro Takeda if (error) 3247be6d3e56SKentaro Takeda goto exit6; 32481da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 32491da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3250be6d3e56SKentaro Takeda exit6: 32519079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 32521da177e4SLinus Torvalds exit5: 32531da177e4SLinus Torvalds dput(new_dentry); 32541da177e4SLinus Torvalds exit4: 32551da177e4SLinus Torvalds dput(old_dentry); 32561da177e4SLinus Torvalds exit3: 32571da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32581da177e4SLinus Torvalds exit2: 32591d957f9bSJan Blunck path_put(&newnd.path); 32602ad94ae6SAl Viro putname(to); 32611da177e4SLinus Torvalds exit1: 32621d957f9bSJan Blunck path_put(&oldnd.path); 32631da177e4SLinus Torvalds putname(from); 32642ad94ae6SAl Viro exit: 32651da177e4SLinus Torvalds return error; 32661da177e4SLinus Torvalds } 32671da177e4SLinus Torvalds 3268a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32695590ff0dSUlrich Drepper { 32705590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32715590ff0dSUlrich Drepper } 32725590ff0dSUlrich Drepper 32731da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32741da177e4SLinus Torvalds { 32751da177e4SLinus Torvalds int len; 32761da177e4SLinus Torvalds 32771da177e4SLinus Torvalds len = PTR_ERR(link); 32781da177e4SLinus Torvalds if (IS_ERR(link)) 32791da177e4SLinus Torvalds goto out; 32801da177e4SLinus Torvalds 32811da177e4SLinus Torvalds len = strlen(link); 32821da177e4SLinus Torvalds if (len > (unsigned) buflen) 32831da177e4SLinus Torvalds len = buflen; 32841da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32851da177e4SLinus Torvalds len = -EFAULT; 32861da177e4SLinus Torvalds out: 32871da177e4SLinus Torvalds return len; 32881da177e4SLinus Torvalds } 32891da177e4SLinus Torvalds 32901da177e4SLinus Torvalds /* 32911da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32921da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32931da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32941da177e4SLinus Torvalds */ 32951da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32961da177e4SLinus Torvalds { 32971da177e4SLinus Torvalds struct nameidata nd; 3298cc314eefSLinus Torvalds void *cookie; 3299694a1764SMarcin Slusarz int res; 3300cc314eefSLinus Torvalds 33011da177e4SLinus Torvalds nd.depth = 0; 3302cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3303694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3304694a1764SMarcin Slusarz return PTR_ERR(cookie); 3305694a1764SMarcin Slusarz 3306694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 33071da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3308cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3309694a1764SMarcin Slusarz return res; 33101da177e4SLinus Torvalds } 33111da177e4SLinus Torvalds 33121da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 33131da177e4SLinus Torvalds { 33141da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 33151da177e4SLinus Torvalds } 33161da177e4SLinus Torvalds 33171da177e4SLinus Torvalds /* get the link contents into pagecache */ 33181da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 33191da177e4SLinus Torvalds { 3320ebd09abbSDuane Griffin char *kaddr; 33211da177e4SLinus Torvalds struct page *page; 33221da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3323090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 33241da177e4SLinus Torvalds if (IS_ERR(page)) 33256fe6900eSNick Piggin return (char*)page; 33261da177e4SLinus Torvalds *ppage = page; 3327ebd09abbSDuane Griffin kaddr = kmap(page); 3328ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3329ebd09abbSDuane Griffin return kaddr; 33301da177e4SLinus Torvalds } 33311da177e4SLinus Torvalds 33321da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 33331da177e4SLinus Torvalds { 33341da177e4SLinus Torvalds struct page *page = NULL; 33351da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 33361da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 33371da177e4SLinus Torvalds if (page) { 33381da177e4SLinus Torvalds kunmap(page); 33391da177e4SLinus Torvalds page_cache_release(page); 33401da177e4SLinus Torvalds } 33411da177e4SLinus Torvalds return res; 33421da177e4SLinus Torvalds } 33431da177e4SLinus Torvalds 3344cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 33451da177e4SLinus Torvalds { 3346cc314eefSLinus Torvalds struct page *page = NULL; 33471da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3348cc314eefSLinus Torvalds return page; 33491da177e4SLinus Torvalds } 33501da177e4SLinus Torvalds 3351cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 33521da177e4SLinus Torvalds { 3353cc314eefSLinus Torvalds struct page *page = cookie; 3354cc314eefSLinus Torvalds 3355cc314eefSLinus Torvalds if (page) { 33561da177e4SLinus Torvalds kunmap(page); 33571da177e4SLinus Torvalds page_cache_release(page); 33581da177e4SLinus Torvalds } 33591da177e4SLinus Torvalds } 33601da177e4SLinus Torvalds 336154566b2cSNick Piggin /* 336254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 336354566b2cSNick Piggin */ 336454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33651da177e4SLinus Torvalds { 33661da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33670adb25d2SKirill Korotaev struct page *page; 3368afddba49SNick Piggin void *fsdata; 3369beb497abSDmitriy Monakhov int err; 33701da177e4SLinus Torvalds char *kaddr; 337154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 337254566b2cSNick Piggin if (nofs) 337354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33741da177e4SLinus Torvalds 33757e53cac4SNeilBrown retry: 3376afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 337754566b2cSNick Piggin flags, &page, &fsdata); 33781da177e4SLinus Torvalds if (err) 3379afddba49SNick Piggin goto fail; 3380afddba49SNick Piggin 33811da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33821da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33831da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3384afddba49SNick Piggin 3385afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3386afddba49SNick Piggin page, fsdata); 33871da177e4SLinus Torvalds if (err < 0) 33881da177e4SLinus Torvalds goto fail; 3389afddba49SNick Piggin if (err < len-1) 3390afddba49SNick Piggin goto retry; 3391afddba49SNick Piggin 33921da177e4SLinus Torvalds mark_inode_dirty(inode); 33931da177e4SLinus Torvalds return 0; 33941da177e4SLinus Torvalds fail: 33951da177e4SLinus Torvalds return err; 33961da177e4SLinus Torvalds } 33971da177e4SLinus Torvalds 33980adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33990adb25d2SKirill Korotaev { 34000adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 340154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 34020adb25d2SKirill Korotaev } 34030adb25d2SKirill Korotaev 340492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 34051da177e4SLinus Torvalds .readlink = generic_readlink, 34061da177e4SLinus Torvalds .follow_link = page_follow_link_light, 34071da177e4SLinus Torvalds .put_link = page_put_link, 34081da177e4SLinus Torvalds }; 34091da177e4SLinus Torvalds 34102d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3411cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 34121da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 34131da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 34141da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 34151da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 34161da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 34171da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 34181da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 34191da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 34201da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 34210adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 34221da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 34231da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3424c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3425d1811465SAl Viro EXPORT_SYMBOL(kern_path); 342616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3427f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 34288c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 34291da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 34301da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 34311da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 34321da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 34331da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 34341da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 34351da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 34361da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 34371da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 34381da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 34391da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 34401da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 34411da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 34421da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3443