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 1391da177e4SLinus Torvalds char * getname(const char __user * filename) 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) { 1501da177e4SLinus Torvalds __putname(tmp); 1511da177e4SLinus Torvalds result = ERR_PTR(retval); 1521da177e4SLinus Torvalds } 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds audit_getname(result); 1551da177e4SLinus Torvalds return result; 1561da177e4SLinus Torvalds } 1571da177e4SLinus Torvalds 1581da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1591da177e4SLinus Torvalds void putname(const char *name) 1601da177e4SLinus Torvalds { 1615ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1621da177e4SLinus Torvalds audit_putname(name); 1631da177e4SLinus Torvalds else 1641da177e4SLinus Torvalds __putname(name); 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1671da177e4SLinus Torvalds #endif 1681da177e4SLinus Torvalds 1695909ccaaSLinus Torvalds /* 1705909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1715909ccaaSLinus Torvalds */ 172b74c79e9SNick Piggin static int acl_permission_check(struct inode *inode, int mask, unsigned int flags, 173b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 1745909ccaaSLinus Torvalds { 1755909ccaaSLinus Torvalds umode_t mode = inode->i_mode; 1765909ccaaSLinus Torvalds 1775909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 1785909ccaaSLinus Torvalds 1795909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1805909ccaaSLinus Torvalds mode >>= 6; 1815909ccaaSLinus Torvalds else { 1825909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 183b74c79e9SNick Piggin int error = check_acl(inode, mask, flags); 1845909ccaaSLinus Torvalds if (error != -EAGAIN) 1855909ccaaSLinus Torvalds return error; 1865909ccaaSLinus Torvalds } 1875909ccaaSLinus Torvalds 1885909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1895909ccaaSLinus Torvalds mode >>= 3; 1905909ccaaSLinus Torvalds } 1915909ccaaSLinus Torvalds 1925909ccaaSLinus Torvalds /* 1935909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 1945909ccaaSLinus Torvalds */ 1955909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 1965909ccaaSLinus Torvalds return 0; 1975909ccaaSLinus Torvalds return -EACCES; 1985909ccaaSLinus Torvalds } 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds /** 2011da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2021da177e4SLinus Torvalds * @inode: inode to check access rights for 2031da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2041da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 205b74c79e9SNick Piggin * @flags IPERM_FLAG_ flags. 2061da177e4SLinus Torvalds * 2071da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2081da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2091da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 210b74c79e9SNick Piggin * are used for other things. 211b74c79e9SNick Piggin * 212b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 213b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 214b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2151da177e4SLinus Torvalds */ 216b74c79e9SNick Piggin int generic_permission(struct inode *inode, int mask, unsigned int flags, 217b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 2181da177e4SLinus Torvalds { 2195909ccaaSLinus Torvalds int ret; 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* 2225909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2231da177e4SLinus Torvalds */ 224b74c79e9SNick Piggin ret = acl_permission_check(inode, mask, flags, check_acl); 2255909ccaaSLinus Torvalds if (ret != -EACCES) 2265909ccaaSLinus Torvalds return ret; 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds /* 2291da177e4SLinus Torvalds * Read/write DACs are always overridable. 2301da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2311da177e4SLinus Torvalds */ 232f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2331da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2341da177e4SLinus Torvalds return 0; 2351da177e4SLinus Torvalds 2361da177e4SLinus Torvalds /* 2371da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2381da177e4SLinus Torvalds */ 2397ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2401da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2411da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2421da177e4SLinus Torvalds return 0; 2431da177e4SLinus Torvalds 2441da177e4SLinus Torvalds return -EACCES; 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 247cb23beb5SChristoph Hellwig /** 248cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 249cb23beb5SChristoph Hellwig * @inode: inode to check permission on 250cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 251cb23beb5SChristoph Hellwig * 252cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 253cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 254cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 255cb23beb5SChristoph Hellwig * are used for other things. 256cb23beb5SChristoph Hellwig */ 257f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2581da177e4SLinus Torvalds { 259e6305c43SAl Viro int retval; 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds if (mask & MAY_WRITE) { 26222590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds /* 2651da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2661da177e4SLinus Torvalds */ 2671da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2681da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2691da177e4SLinus Torvalds return -EROFS; 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds /* 2721da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2731da177e4SLinus Torvalds */ 2741da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2751da177e4SLinus Torvalds return -EACCES; 2761da177e4SLinus Torvalds } 2771da177e4SLinus Torvalds 278acfa4380SAl Viro if (inode->i_op->permission) 279b74c79e9SNick Piggin retval = inode->i_op->permission(inode, mask, 0); 280f696a365SMiklos Szeredi else 281b74c79e9SNick Piggin retval = generic_permission(inode, mask, 0, 282b74c79e9SNick Piggin inode->i_op->check_acl); 283f696a365SMiklos Szeredi 2841da177e4SLinus Torvalds if (retval) 2851da177e4SLinus Torvalds return retval; 2861da177e4SLinus Torvalds 28708ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 28808ce5f16SSerge E. Hallyn if (retval) 28908ce5f16SSerge E. Hallyn return retval; 29008ce5f16SSerge E. Hallyn 291d09ca739SEric Paris return security_inode_permission(inode, mask); 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds 294e4543eddSChristoph Hellwig /** 2958c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2968c744fb8SChristoph Hellwig * @file: file to check access rights for 2978c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2988c744fb8SChristoph Hellwig * 2998c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3008c744fb8SChristoph Hellwig * file. 3018c744fb8SChristoph Hellwig * 3028c744fb8SChristoph Hellwig * Note: 3038c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 304cb23beb5SChristoph Hellwig * be done using inode_permission(). 3058c744fb8SChristoph Hellwig */ 3068c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3078c744fb8SChristoph Hellwig { 308f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3098c744fb8SChristoph Hellwig } 3108c744fb8SChristoph Hellwig 3111da177e4SLinus Torvalds /* 3121da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3131da177e4SLinus Torvalds * put_write_access() releases this write permission. 3141da177e4SLinus Torvalds * This is used for regular files. 3151da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3161da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3171da177e4SLinus Torvalds * can have the following values: 3181da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3191da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3201da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3211da177e4SLinus Torvalds * 3221da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3231da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3241da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3251da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3261da177e4SLinus Torvalds * the inode->i_lock spinlock. 3271da177e4SLinus Torvalds */ 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3301da177e4SLinus Torvalds { 3311da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3321da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3331da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3341da177e4SLinus Torvalds return -ETXTBSY; 3351da177e4SLinus Torvalds } 3361da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3371da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3381da177e4SLinus Torvalds 3391da177e4SLinus Torvalds return 0; 3401da177e4SLinus Torvalds } 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds int deny_write_access(struct file * file) 3431da177e4SLinus Torvalds { 3440f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3471da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3481da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3491da177e4SLinus Torvalds return -ETXTBSY; 3501da177e4SLinus Torvalds } 3511da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3521da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds return 0; 3551da177e4SLinus Torvalds } 3561da177e4SLinus Torvalds 3571d957f9bSJan Blunck /** 3585dd784d0SJan Blunck * path_get - get a reference to a path 3595dd784d0SJan Blunck * @path: path to get the reference to 3605dd784d0SJan Blunck * 3615dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3625dd784d0SJan Blunck */ 3635dd784d0SJan Blunck void path_get(struct path *path) 3645dd784d0SJan Blunck { 3655dd784d0SJan Blunck mntget(path->mnt); 3665dd784d0SJan Blunck dget(path->dentry); 3675dd784d0SJan Blunck } 3685dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3695dd784d0SJan Blunck 3705dd784d0SJan Blunck /** 3711d957f9bSJan Blunck * path_put - put a reference to a path 3721d957f9bSJan Blunck * @path: path to put the reference to 3731d957f9bSJan Blunck * 3741d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3751d957f9bSJan Blunck */ 3761d957f9bSJan Blunck void path_put(struct path *path) 3771da177e4SLinus Torvalds { 3781d957f9bSJan Blunck dput(path->dentry); 3791d957f9bSJan Blunck mntput(path->mnt); 3801da177e4SLinus Torvalds } 3811d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3821da177e4SLinus Torvalds 383834f2a4aSTrond Myklebust /** 38431e6b01fSNick Piggin * nameidata_drop_rcu - drop this nameidata out of rcu-walk 38531e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 38631e6b01fSNick Piggin * @Returns: 0 on success, -ECHLID on failure 38731e6b01fSNick Piggin * 38831e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 38931e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). __drop_rcu* functions attempt 39031e6b01fSNick Piggin * to drop out of rcu-walk mode and take normal reference counts on dentries 39131e6b01fSNick Piggin * and vfsmounts to transition to rcu-walk mode. __drop_rcu* functions take 39231e6b01fSNick Piggin * refcounts at the last known good point before rcu-walk got stuck, so 39331e6b01fSNick Piggin * ref-walk may continue from there. If this is not successful (eg. a seqcount 39431e6b01fSNick Piggin * has changed), then failure is returned and path walk restarts from the 39531e6b01fSNick Piggin * beginning in ref-walk mode. 39631e6b01fSNick Piggin * 39731e6b01fSNick Piggin * nameidata_drop_rcu attempts to drop the current nd->path and nd->root into 39831e6b01fSNick Piggin * ref-walk. Must be called from rcu-walk context. 39931e6b01fSNick Piggin */ 40031e6b01fSNick Piggin static int nameidata_drop_rcu(struct nameidata *nd) 40131e6b01fSNick Piggin { 40231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 40331e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 40431e6b01fSNick Piggin 40531e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 40631e6b01fSNick Piggin if (nd->root.mnt) { 40731e6b01fSNick Piggin spin_lock(&fs->lock); 40831e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 40931e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 41031e6b01fSNick Piggin goto err_root; 41131e6b01fSNick Piggin } 41231e6b01fSNick Piggin spin_lock(&dentry->d_lock); 41331e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 41431e6b01fSNick Piggin goto err; 41531e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 41631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 41731e6b01fSNick Piggin if (nd->root.mnt) { 41831e6b01fSNick Piggin path_get(&nd->root); 41931e6b01fSNick Piggin spin_unlock(&fs->lock); 42031e6b01fSNick Piggin } 42131e6b01fSNick Piggin mntget(nd->path.mnt); 42231e6b01fSNick Piggin 42331e6b01fSNick Piggin rcu_read_unlock(); 42431e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 42531e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 42631e6b01fSNick Piggin return 0; 42731e6b01fSNick Piggin err: 42831e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 42931e6b01fSNick Piggin err_root: 43031e6b01fSNick Piggin if (nd->root.mnt) 43131e6b01fSNick Piggin spin_unlock(&fs->lock); 43231e6b01fSNick Piggin return -ECHILD; 43331e6b01fSNick Piggin } 43431e6b01fSNick Piggin 43531e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 43631e6b01fSNick Piggin static inline int nameidata_drop_rcu_maybe(struct nameidata *nd) 43731e6b01fSNick Piggin { 43831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) 43931e6b01fSNick Piggin return nameidata_drop_rcu(nd); 44031e6b01fSNick Piggin return 0; 44131e6b01fSNick Piggin } 44231e6b01fSNick Piggin 44331e6b01fSNick Piggin /** 44431e6b01fSNick Piggin * nameidata_dentry_drop_rcu - drop nameidata and dentry out of rcu-walk 44531e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 44631e6b01fSNick Piggin * @dentry: dentry to drop 44731e6b01fSNick Piggin * @Returns: 0 on success, -ECHLID on failure 44831e6b01fSNick Piggin * 44931e6b01fSNick Piggin * nameidata_dentry_drop_rcu attempts to drop the current nd->path and nd->root, 45031e6b01fSNick Piggin * and dentry into ref-walk. @dentry must be a path found by a do_lookup call on 45131e6b01fSNick Piggin * @nd. Must be called from rcu-walk context. 45231e6b01fSNick Piggin */ 45331e6b01fSNick Piggin static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry) 45431e6b01fSNick Piggin { 45531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 45631e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 45731e6b01fSNick Piggin 45831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 45931e6b01fSNick Piggin if (nd->root.mnt) { 46031e6b01fSNick Piggin spin_lock(&fs->lock); 46131e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 46231e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 46331e6b01fSNick Piggin goto err_root; 46431e6b01fSNick Piggin } 46531e6b01fSNick Piggin spin_lock(&parent->d_lock); 46631e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 46731e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 46831e6b01fSNick Piggin goto err; 46931e6b01fSNick Piggin /* 47031e6b01fSNick Piggin * If the sequence check on the child dentry passed, then the child has 47131e6b01fSNick Piggin * not been removed from its parent. This means the parent dentry must 47231e6b01fSNick Piggin * be valid and able to take a reference at this point. 47331e6b01fSNick Piggin */ 47431e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 47531e6b01fSNick Piggin BUG_ON(!parent->d_count); 47631e6b01fSNick Piggin parent->d_count++; 47731e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 47831e6b01fSNick Piggin spin_unlock(&parent->d_lock); 47931e6b01fSNick Piggin if (nd->root.mnt) { 48031e6b01fSNick Piggin path_get(&nd->root); 48131e6b01fSNick Piggin spin_unlock(&fs->lock); 48231e6b01fSNick Piggin } 48331e6b01fSNick Piggin mntget(nd->path.mnt); 48431e6b01fSNick Piggin 48531e6b01fSNick Piggin rcu_read_unlock(); 48631e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 48731e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 48831e6b01fSNick Piggin return 0; 48931e6b01fSNick Piggin err: 49031e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 49131e6b01fSNick Piggin spin_unlock(&parent->d_lock); 49231e6b01fSNick Piggin err_root: 49331e6b01fSNick Piggin if (nd->root.mnt) 49431e6b01fSNick Piggin spin_unlock(&fs->lock); 49531e6b01fSNick Piggin return -ECHILD; 49631e6b01fSNick Piggin } 49731e6b01fSNick Piggin 49831e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 49931e6b01fSNick Piggin static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry) 50031e6b01fSNick Piggin { 50131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) 50231e6b01fSNick Piggin return nameidata_dentry_drop_rcu(nd, dentry); 50331e6b01fSNick Piggin return 0; 50431e6b01fSNick Piggin } 50531e6b01fSNick Piggin 50631e6b01fSNick Piggin /** 50731e6b01fSNick Piggin * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk 50831e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 50931e6b01fSNick Piggin * @Returns: 0 on success, -ECHLID on failure 51031e6b01fSNick Piggin * 51131e6b01fSNick Piggin * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. 51231e6b01fSNick Piggin * nd->path should be the final element of the lookup, so nd->root is discarded. 51331e6b01fSNick Piggin * Must be called from rcu-walk context. 51431e6b01fSNick Piggin */ 51531e6b01fSNick Piggin static int nameidata_drop_rcu_last(struct nameidata *nd) 51631e6b01fSNick Piggin { 51731e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 51831e6b01fSNick Piggin 51931e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 52031e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 52131e6b01fSNick Piggin nd->root.mnt = NULL; 52231e6b01fSNick Piggin spin_lock(&dentry->d_lock); 52331e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 52431e6b01fSNick Piggin goto err_unlock; 52531e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 52631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 52731e6b01fSNick Piggin 52831e6b01fSNick Piggin mntget(nd->path.mnt); 52931e6b01fSNick Piggin 53031e6b01fSNick Piggin rcu_read_unlock(); 53131e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 53231e6b01fSNick Piggin 53331e6b01fSNick Piggin return 0; 53431e6b01fSNick Piggin 53531e6b01fSNick Piggin err_unlock: 53631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 53731e6b01fSNick Piggin rcu_read_unlock(); 53831e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 53931e6b01fSNick Piggin return -ECHILD; 54031e6b01fSNick Piggin } 54131e6b01fSNick Piggin 54231e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 54331e6b01fSNick Piggin static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd) 54431e6b01fSNick Piggin { 54531e6b01fSNick Piggin if (likely(nd->flags & LOOKUP_RCU)) 54631e6b01fSNick Piggin return nameidata_drop_rcu_last(nd); 54731e6b01fSNick Piggin return 0; 54831e6b01fSNick Piggin } 54931e6b01fSNick Piggin 55031e6b01fSNick Piggin /** 551834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 552834f2a4aSTrond Myklebust * @nd: pointer to nameidata 553834f2a4aSTrond Myklebust */ 554834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 555834f2a4aSTrond Myklebust { 5560f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 557834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 558834f2a4aSTrond Myklebust else 559834f2a4aSTrond Myklebust fput(nd->intent.open.file); 560834f2a4aSTrond Myklebust } 561834f2a4aSTrond Myklebust 56234286d66SNick Piggin static int d_revalidate(struct dentry *dentry, struct nameidata *nd) 56334286d66SNick Piggin { 56434286d66SNick Piggin int status; 56534286d66SNick Piggin 56634286d66SNick Piggin status = dentry->d_op->d_revalidate(dentry, nd); 56734286d66SNick Piggin if (status == -ECHILD) { 56834286d66SNick Piggin if (nameidata_dentry_drop_rcu(nd, dentry)) 56934286d66SNick Piggin return status; 57034286d66SNick Piggin status = dentry->d_op->d_revalidate(dentry, nd); 57134286d66SNick Piggin } 57234286d66SNick Piggin 57334286d66SNick Piggin return status; 57434286d66SNick Piggin } 57534286d66SNick Piggin 576bcdc5e01SIan Kent static inline struct dentry * 577bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 578bcdc5e01SIan Kent { 57934286d66SNick Piggin int status; 58034286d66SNick Piggin 58134286d66SNick Piggin status = d_revalidate(dentry, nd); 582bcdc5e01SIan Kent if (unlikely(status <= 0)) { 583bcdc5e01SIan Kent /* 584bcdc5e01SIan Kent * The dentry failed validation. 585bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 586bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 587bcdc5e01SIan Kent * to return a fail status. 588bcdc5e01SIan Kent */ 58934286d66SNick Piggin if (status < 0) { 59034286d66SNick Piggin /* If we're in rcu-walk, we don't have a ref */ 59134286d66SNick Piggin if (!(nd->flags & LOOKUP_RCU)) 59234286d66SNick Piggin dput(dentry); 59334286d66SNick Piggin dentry = ERR_PTR(status); 59434286d66SNick Piggin 59534286d66SNick Piggin } else { 59634286d66SNick Piggin /* Don't d_invalidate in rcu-walk mode */ 59734286d66SNick Piggin if (nameidata_dentry_drop_rcu_maybe(nd, dentry)) 59834286d66SNick Piggin return ERR_PTR(-ECHILD); 599bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 600bcdc5e01SIan Kent dput(dentry); 601bcdc5e01SIan Kent dentry = NULL; 602bcdc5e01SIan Kent } 603bcdc5e01SIan Kent } 604bcdc5e01SIan Kent } 605bcdc5e01SIan Kent return dentry; 606bcdc5e01SIan Kent } 607bcdc5e01SIan Kent 608fb045adbSNick Piggin static inline int need_reval_dot(struct dentry *dentry) 609fb045adbSNick Piggin { 610fb045adbSNick Piggin if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 611fb045adbSNick Piggin return 0; 612fb045adbSNick Piggin 613fb045adbSNick Piggin if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 614fb045adbSNick Piggin return 0; 615fb045adbSNick Piggin 616fb045adbSNick Piggin return 1; 617fb045adbSNick Piggin } 618fb045adbSNick Piggin 6191da177e4SLinus Torvalds /* 62039159de2SJeff Layton * force_reval_path - force revalidation of a dentry 62139159de2SJeff Layton * 62239159de2SJeff Layton * In some situations the path walking code will trust dentries without 62339159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 62439159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 62539159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 62639159de2SJeff Layton * a d_revalidate call before proceeding. 62739159de2SJeff Layton * 62839159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 62939159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 63039159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 63139159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 63239159de2SJeff Layton * to the path if necessary. 63339159de2SJeff Layton */ 63439159de2SJeff Layton static int 63539159de2SJeff Layton force_reval_path(struct path *path, struct nameidata *nd) 63639159de2SJeff Layton { 63739159de2SJeff Layton int status; 63839159de2SJeff Layton struct dentry *dentry = path->dentry; 63939159de2SJeff Layton 64039159de2SJeff Layton /* 64139159de2SJeff Layton * only check on filesystems where it's possible for the dentry to 642fb045adbSNick Piggin * become stale. 64339159de2SJeff Layton */ 644fb045adbSNick Piggin if (!need_reval_dot(dentry)) 64539159de2SJeff Layton return 0; 64639159de2SJeff Layton 64734286d66SNick Piggin status = d_revalidate(dentry, nd); 64839159de2SJeff Layton if (status > 0) 64939159de2SJeff Layton return 0; 65039159de2SJeff Layton 65139159de2SJeff Layton if (!status) { 65239159de2SJeff Layton d_invalidate(dentry); 65339159de2SJeff Layton status = -ESTALE; 65439159de2SJeff Layton } 65539159de2SJeff Layton return status; 65639159de2SJeff Layton } 65739159de2SJeff Layton 65839159de2SJeff Layton /* 659b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 660b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 661b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 6621da177e4SLinus Torvalds * 6631da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 664b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 6651da177e4SLinus Torvalds * complete permission check. 6661da177e4SLinus Torvalds */ 667b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 6681da177e4SLinus Torvalds { 6695909ccaaSLinus Torvalds int ret; 6701da177e4SLinus Torvalds 671cb9179eaSLinus Torvalds if (inode->i_op->permission) { 672b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 673b74c79e9SNick Piggin } else { 674b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 675b74c79e9SNick Piggin inode->i_op->check_acl); 676cb9179eaSLinus Torvalds } 677b74c79e9SNick Piggin if (likely(!ret)) 6781da177e4SLinus Torvalds goto ok; 679b74c79e9SNick Piggin if (ret == -ECHILD) 68031e6b01fSNick Piggin return ret; 6811da177e4SLinus Torvalds 682f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 6831da177e4SLinus Torvalds goto ok; 6841da177e4SLinus Torvalds 6855909ccaaSLinus Torvalds return ret; 6861da177e4SLinus Torvalds ok: 687b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 6881da177e4SLinus Torvalds } 6891da177e4SLinus Torvalds 6902a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6912a737871SAl Viro { 692f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 693f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6942a737871SAl Viro } 6952a737871SAl Viro 6966de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6976de88d72SAl Viro 69831e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 69931e6b01fSNick Piggin { 70031e6b01fSNick Piggin if (!nd->root.mnt) { 70131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 702c28cc364SNick Piggin unsigned seq; 703c28cc364SNick Piggin 704c28cc364SNick Piggin do { 705c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 70631e6b01fSNick Piggin nd->root = fs->root; 707c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 70831e6b01fSNick Piggin } 70931e6b01fSNick Piggin } 71031e6b01fSNick Piggin 711f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 7121da177e4SLinus Torvalds { 71331e6b01fSNick Piggin int ret; 71431e6b01fSNick Piggin 7151da177e4SLinus Torvalds if (IS_ERR(link)) 7161da177e4SLinus Torvalds goto fail; 7171da177e4SLinus Torvalds 7181da177e4SLinus Torvalds if (*link == '/') { 7192a737871SAl Viro set_root(nd); 7201d957f9bSJan Blunck path_put(&nd->path); 7212a737871SAl Viro nd->path = nd->root; 7222a737871SAl Viro path_get(&nd->root); 7231da177e4SLinus Torvalds } 72431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 725b4091d5fSChristoph Hellwig 72631e6b01fSNick Piggin ret = link_path_walk(link, nd); 72731e6b01fSNick Piggin return ret; 7281da177e4SLinus Torvalds fail: 7291d957f9bSJan Blunck path_put(&nd->path); 7301da177e4SLinus Torvalds return PTR_ERR(link); 7311da177e4SLinus Torvalds } 7321da177e4SLinus Torvalds 7331d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 734051d3812SIan Kent { 735051d3812SIan Kent dput(path->dentry); 7364ac91378SJan Blunck if (path->mnt != nd->path.mnt) 737051d3812SIan Kent mntput(path->mnt); 738051d3812SIan Kent } 739051d3812SIan Kent 740051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 741051d3812SIan Kent { 74231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7434ac91378SJan Blunck dput(nd->path.dentry); 74431e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7454ac91378SJan Blunck mntput(nd->path.mnt); 7469a229683SHuang Shijie } 74731e6b01fSNick Piggin nd->path.mnt = path->mnt; 7484ac91378SJan Blunck nd->path.dentry = path->dentry; 749051d3812SIan Kent } 750051d3812SIan Kent 751def4af30SAl Viro static __always_inline int 752def4af30SAl Viro __do_follow_link(struct path *path, struct nameidata *nd, void **p) 7531da177e4SLinus Torvalds { 7541da177e4SLinus Torvalds int error; 755cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 7561da177e4SLinus Torvalds 757d671a1cbSAl Viro touch_atime(path->mnt, dentry); 7581da177e4SLinus Torvalds nd_set_link(nd, NULL); 759cd4e91d3SAl Viro 7604ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 761051d3812SIan Kent path_to_nameidata(path, nd); 76231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 763051d3812SIan Kent dget(dentry); 764051d3812SIan Kent } 765cd4e91d3SAl Viro mntget(path->mnt); 76631e6b01fSNick Piggin 76786acdca1SAl Viro nd->last_type = LAST_BIND; 768def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 769def4af30SAl Viro error = PTR_ERR(*p); 770def4af30SAl Viro if (!IS_ERR(*p)) { 7711da177e4SLinus Torvalds char *s = nd_get_link(nd); 772cc314eefSLinus Torvalds error = 0; 7731da177e4SLinus Torvalds if (s) 7741da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 77539159de2SJeff Layton else if (nd->last_type == LAST_BIND) { 77639159de2SJeff Layton error = force_reval_path(&nd->path, nd); 77739159de2SJeff Layton if (error) 77839159de2SJeff Layton path_put(&nd->path); 77939159de2SJeff Layton } 7801da177e4SLinus Torvalds } 7811da177e4SLinus Torvalds return error; 7821da177e4SLinus Torvalds } 7831da177e4SLinus Torvalds 7841da177e4SLinus Torvalds /* 7851da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 7861da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 7871da177e4SLinus Torvalds * 7881da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 7891da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 7901da177e4SLinus Torvalds */ 79190ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 7921da177e4SLinus Torvalds { 793def4af30SAl Viro void *cookie; 7941da177e4SLinus Torvalds int err = -ELOOP; 7951da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 7961da177e4SLinus Torvalds goto loop; 7971da177e4SLinus Torvalds if (current->total_link_count >= 40) 7981da177e4SLinus Torvalds goto loop; 7991da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 8001da177e4SLinus Torvalds cond_resched(); 80190ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 8021da177e4SLinus Torvalds if (err) 8031da177e4SLinus Torvalds goto loop; 8041da177e4SLinus Torvalds current->link_count++; 8051da177e4SLinus Torvalds current->total_link_count++; 8061da177e4SLinus Torvalds nd->depth++; 807def4af30SAl Viro err = __do_follow_link(path, nd, &cookie); 808def4af30SAl Viro if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link) 809def4af30SAl Viro path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie); 810258fa999SAl Viro path_put(path); 8111da177e4SLinus Torvalds current->link_count--; 8121da177e4SLinus Torvalds nd->depth--; 8131da177e4SLinus Torvalds return err; 8141da177e4SLinus Torvalds loop: 8151d957f9bSJan Blunck path_put_conditional(path, nd); 8161d957f9bSJan Blunck path_put(&nd->path); 8171da177e4SLinus Torvalds return err; 8181da177e4SLinus Torvalds } 8191da177e4SLinus Torvalds 82031e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 82131e6b01fSNick Piggin { 82231e6b01fSNick Piggin struct vfsmount *parent; 82331e6b01fSNick Piggin struct dentry *mountpoint; 82431e6b01fSNick Piggin 82531e6b01fSNick Piggin parent = path->mnt->mnt_parent; 82631e6b01fSNick Piggin if (parent == path->mnt) 82731e6b01fSNick Piggin return 0; 82831e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 82931e6b01fSNick Piggin path->dentry = mountpoint; 83031e6b01fSNick Piggin path->mnt = parent; 83131e6b01fSNick Piggin return 1; 83231e6b01fSNick Piggin } 83331e6b01fSNick Piggin 834bab77ebfSAl Viro int follow_up(struct path *path) 8351da177e4SLinus Torvalds { 8361da177e4SLinus Torvalds struct vfsmount *parent; 8371da177e4SLinus Torvalds struct dentry *mountpoint; 83899b7db7bSNick Piggin 83999b7db7bSNick Piggin br_read_lock(vfsmount_lock); 840bab77ebfSAl Viro parent = path->mnt->mnt_parent; 841bab77ebfSAl Viro if (parent == path->mnt) { 84299b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 8431da177e4SLinus Torvalds return 0; 8441da177e4SLinus Torvalds } 8451da177e4SLinus Torvalds mntget(parent); 846bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 84799b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 848bab77ebfSAl Viro dput(path->dentry); 849bab77ebfSAl Viro path->dentry = mountpoint; 850bab77ebfSAl Viro mntput(path->mnt); 851bab77ebfSAl Viro path->mnt = parent; 8521da177e4SLinus Torvalds return 1; 8531da177e4SLinus Torvalds } 8541da177e4SLinus Torvalds 855b5c84bf6SNick Piggin /* 856b5c84bf6SNick Piggin * serialization is taken care of in namespace.c 8571da177e4SLinus Torvalds */ 85831e6b01fSNick Piggin static void __follow_mount_rcu(struct nameidata *nd, struct path *path, 85931e6b01fSNick Piggin struct inode **inode) 86031e6b01fSNick Piggin { 86131e6b01fSNick Piggin while (d_mountpoint(path->dentry)) { 86231e6b01fSNick Piggin struct vfsmount *mounted; 86331e6b01fSNick Piggin mounted = __lookup_mnt(path->mnt, path->dentry, 1); 86431e6b01fSNick Piggin if (!mounted) 86531e6b01fSNick Piggin return; 86631e6b01fSNick Piggin path->mnt = mounted; 86731e6b01fSNick Piggin path->dentry = mounted->mnt_root; 86831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&path->dentry->d_seq); 86931e6b01fSNick Piggin *inode = path->dentry->d_inode; 87031e6b01fSNick Piggin } 87131e6b01fSNick Piggin } 87231e6b01fSNick Piggin 873463ffb2eSAl Viro static int __follow_mount(struct path *path) 874463ffb2eSAl Viro { 875463ffb2eSAl Viro int res = 0; 876463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 8771c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 878463ffb2eSAl Viro if (!mounted) 879463ffb2eSAl Viro break; 880463ffb2eSAl Viro dput(path->dentry); 881463ffb2eSAl Viro if (res) 882463ffb2eSAl Viro mntput(path->mnt); 883463ffb2eSAl Viro path->mnt = mounted; 884463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 885463ffb2eSAl Viro res = 1; 886463ffb2eSAl Viro } 887463ffb2eSAl Viro return res; 888463ffb2eSAl Viro } 889463ffb2eSAl Viro 89079ed0226SAl Viro static void follow_mount(struct path *path) 8911da177e4SLinus Torvalds { 89279ed0226SAl Viro while (d_mountpoint(path->dentry)) { 8931c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 8941da177e4SLinus Torvalds if (!mounted) 8951da177e4SLinus Torvalds break; 89679ed0226SAl Viro dput(path->dentry); 89779ed0226SAl Viro mntput(path->mnt); 89879ed0226SAl Viro path->mnt = mounted; 89979ed0226SAl Viro path->dentry = dget(mounted->mnt_root); 9001da177e4SLinus Torvalds } 9011da177e4SLinus Torvalds } 9021da177e4SLinus Torvalds 9039393bd07SAl Viro int follow_down(struct path *path) 9041da177e4SLinus Torvalds { 9051da177e4SLinus Torvalds struct vfsmount *mounted; 9061da177e4SLinus Torvalds 9071c755af4SAl Viro mounted = lookup_mnt(path); 9081da177e4SLinus Torvalds if (mounted) { 9099393bd07SAl Viro dput(path->dentry); 9109393bd07SAl Viro mntput(path->mnt); 9119393bd07SAl Viro path->mnt = mounted; 9129393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9131da177e4SLinus Torvalds return 1; 9141da177e4SLinus Torvalds } 9151da177e4SLinus Torvalds return 0; 9161da177e4SLinus Torvalds } 9171da177e4SLinus Torvalds 91831e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 91931e6b01fSNick Piggin { 92031e6b01fSNick Piggin struct inode *inode = nd->inode; 92131e6b01fSNick Piggin 92231e6b01fSNick Piggin set_root_rcu(nd); 92331e6b01fSNick Piggin 92431e6b01fSNick Piggin while(1) { 92531e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 92631e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 92731e6b01fSNick Piggin break; 92831e6b01fSNick Piggin } 92931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 93031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 93131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 93231e6b01fSNick Piggin unsigned seq; 93331e6b01fSNick Piggin 93431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 93531e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 93631e6b01fSNick Piggin return -ECHILD; 93731e6b01fSNick Piggin inode = parent->d_inode; 93831e6b01fSNick Piggin nd->path.dentry = parent; 93931e6b01fSNick Piggin nd->seq = seq; 94031e6b01fSNick Piggin break; 94131e6b01fSNick Piggin } 94231e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 94331e6b01fSNick Piggin break; 94431e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 94531e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 94631e6b01fSNick Piggin } 94731e6b01fSNick Piggin __follow_mount_rcu(nd, &nd->path, &inode); 94831e6b01fSNick Piggin nd->inode = inode; 94931e6b01fSNick Piggin 95031e6b01fSNick Piggin return 0; 95131e6b01fSNick Piggin } 95231e6b01fSNick Piggin 95331e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 9541da177e4SLinus Torvalds { 9552a737871SAl Viro set_root(nd); 956e518ddb7SAndreas Mohr 9571da177e4SLinus Torvalds while(1) { 9584ac91378SJan Blunck struct dentry *old = nd->path.dentry; 9591da177e4SLinus Torvalds 9602a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 9612a737871SAl Viro nd->path.mnt == nd->root.mnt) { 9621da177e4SLinus Torvalds break; 9631da177e4SLinus Torvalds } 9644ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 9653088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 9663088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 9671da177e4SLinus Torvalds dput(old); 9681da177e4SLinus Torvalds break; 9691da177e4SLinus Torvalds } 9703088dd70SAl Viro if (!follow_up(&nd->path)) 9711da177e4SLinus Torvalds break; 9721da177e4SLinus Torvalds } 97379ed0226SAl Viro follow_mount(&nd->path); 97431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 9751da177e4SLinus Torvalds } 9761da177e4SLinus Torvalds 9771da177e4SLinus Torvalds /* 978baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 979baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 980baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 981baa03890SNick Piggin * have verified that no child exists while under i_mutex. 982baa03890SNick Piggin */ 983baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 984baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 985baa03890SNick Piggin { 986baa03890SNick Piggin struct inode *inode = parent->d_inode; 987baa03890SNick Piggin struct dentry *dentry; 988baa03890SNick Piggin struct dentry *old; 989baa03890SNick Piggin 990baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 991baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 992baa03890SNick Piggin return ERR_PTR(-ENOENT); 993baa03890SNick Piggin 994baa03890SNick Piggin dentry = d_alloc(parent, name); 995baa03890SNick Piggin if (unlikely(!dentry)) 996baa03890SNick Piggin return ERR_PTR(-ENOMEM); 997baa03890SNick Piggin 998baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 999baa03890SNick Piggin if (unlikely(old)) { 1000baa03890SNick Piggin dput(dentry); 1001baa03890SNick Piggin dentry = old; 1002baa03890SNick Piggin } 1003baa03890SNick Piggin return dentry; 1004baa03890SNick Piggin } 1005baa03890SNick Piggin 1006baa03890SNick Piggin /* 10071da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 10081da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 10091da177e4SLinus Torvalds * It _is_ time-critical. 10101da177e4SLinus Torvalds */ 10111da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 101231e6b01fSNick Piggin struct path *path, struct inode **inode) 10131da177e4SLinus Torvalds { 10144ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 101531e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 10166e6b1bd1SAl Viro struct inode *dir; 10173cac260aSAl Viro /* 10183cac260aSAl Viro * See if the low-level filesystem might want 10193cac260aSAl Viro * to use its own hash.. 10203cac260aSAl Viro */ 1021fb045adbSNick Piggin if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 102231e6b01fSNick Piggin int err = parent->d_op->d_hash(parent, nd->inode, name); 10233cac260aSAl Viro if (err < 0) 10243cac260aSAl Viro return err; 10253cac260aSAl Viro } 10261da177e4SLinus Torvalds 1027b04f784eSNick Piggin /* 1028b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1029b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1030b04f784eSNick Piggin * do the non-racy lookup, below. 1031b04f784eSNick Piggin */ 103231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 103331e6b01fSNick Piggin unsigned seq; 103431e6b01fSNick Piggin 103531e6b01fSNick Piggin *inode = nd->inode; 103631e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 103731e6b01fSNick Piggin if (!dentry) { 103831e6b01fSNick Piggin if (nameidata_drop_rcu(nd)) 103931e6b01fSNick Piggin return -ECHILD; 104031e6b01fSNick Piggin goto need_lookup; 104131e6b01fSNick Piggin } 104231e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 104331e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 104431e6b01fSNick Piggin return -ECHILD; 104531e6b01fSNick Piggin 104631e6b01fSNick Piggin nd->seq = seq; 104734286d66SNick Piggin if (dentry->d_flags & DCACHE_OP_REVALIDATE) 104831e6b01fSNick Piggin goto need_revalidate; 104931e6b01fSNick Piggin path->mnt = mnt; 105031e6b01fSNick Piggin path->dentry = dentry; 105131e6b01fSNick Piggin __follow_mount_rcu(nd, path, inode); 105231e6b01fSNick Piggin } else { 105331e6b01fSNick Piggin dentry = __d_lookup(parent, name); 10541da177e4SLinus Torvalds if (!dentry) 10551da177e4SLinus Torvalds goto need_lookup; 10562e2e88eaSNick Piggin found: 1057fb045adbSNick Piggin if (dentry->d_flags & DCACHE_OP_REVALIDATE) 10581da177e4SLinus Torvalds goto need_revalidate; 10591da177e4SLinus Torvalds done: 10601da177e4SLinus Torvalds path->mnt = mnt; 10611da177e4SLinus Torvalds path->dentry = dentry; 1062634ee701SAl Viro __follow_mount(path); 106331e6b01fSNick Piggin *inode = path->dentry->d_inode; 106431e6b01fSNick Piggin } 10651da177e4SLinus Torvalds return 0; 10661da177e4SLinus Torvalds 10671da177e4SLinus Torvalds need_lookup: 10686e6b1bd1SAl Viro dir = parent->d_inode; 106931e6b01fSNick Piggin BUG_ON(nd->inode != dir); 10706e6b1bd1SAl Viro 10716e6b1bd1SAl Viro mutex_lock(&dir->i_mutex); 10726e6b1bd1SAl Viro /* 10736e6b1bd1SAl Viro * First re-do the cached lookup just in case it was created 1074b04f784eSNick Piggin * while we waited for the directory semaphore, or the first 1075b04f784eSNick Piggin * lookup failed due to an unrelated rename. 10766e6b1bd1SAl Viro * 1077b04f784eSNick Piggin * This could use version numbering or similar to avoid unnecessary 1078b04f784eSNick Piggin * cache lookups, but then we'd have to do the first lookup in the 1079b04f784eSNick Piggin * non-racy way. However in the common case here, everything should 1080b04f784eSNick Piggin * be hot in cache, so would it be a big win? 10816e6b1bd1SAl Viro */ 10826e6b1bd1SAl Viro dentry = d_lookup(parent, name); 1083baa03890SNick Piggin if (likely(!dentry)) { 1084baa03890SNick Piggin dentry = d_alloc_and_lookup(parent, name, nd); 10856e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 10866e6b1bd1SAl Viro if (IS_ERR(dentry)) 10876e6b1bd1SAl Viro goto fail; 10886e6b1bd1SAl Viro goto done; 10896e6b1bd1SAl Viro } 10906e6b1bd1SAl Viro /* 10916e6b1bd1SAl Viro * Uhhuh! Nasty case: the cache was re-populated while 10926e6b1bd1SAl Viro * we waited on the semaphore. Need to revalidate. 10936e6b1bd1SAl Viro */ 10946e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 10952e2e88eaSNick Piggin goto found; 10961da177e4SLinus Torvalds 10971da177e4SLinus Torvalds need_revalidate: 1098bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 1099bcdc5e01SIan Kent if (!dentry) 11001da177e4SLinus Torvalds goto need_lookup; 1101bcdc5e01SIan Kent if (IS_ERR(dentry)) 1102bcdc5e01SIan Kent goto fail; 1103bcdc5e01SIan Kent goto done; 11041da177e4SLinus Torvalds 11051da177e4SLinus Torvalds fail: 11061da177e4SLinus Torvalds return PTR_ERR(dentry); 11071da177e4SLinus Torvalds } 11081da177e4SLinus Torvalds 11091da177e4SLinus Torvalds /* 1110ac278a9cSAl Viro * This is a temporary kludge to deal with "automount" symlinks; proper 1111ac278a9cSAl Viro * solution is to trigger them on follow_mount(), so that do_lookup() 1112ac278a9cSAl Viro * would DTRT. To be killed before 2.6.34-final. 1113ac278a9cSAl Viro */ 1114ac278a9cSAl Viro static inline int follow_on_final(struct inode *inode, unsigned lookup_flags) 1115ac278a9cSAl Viro { 1116ac278a9cSAl Viro return inode && unlikely(inode->i_op->follow_link) && 1117ac278a9cSAl Viro ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode)); 1118ac278a9cSAl Viro } 1119ac278a9cSAl Viro 1120ac278a9cSAl Viro /* 11211da177e4SLinus Torvalds * Name resolution. 1122ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1123ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 11241da177e4SLinus Torvalds * 1125ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1126ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 11271da177e4SLinus Torvalds */ 11286de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 11291da177e4SLinus Torvalds { 11301da177e4SLinus Torvalds struct path next; 11311da177e4SLinus Torvalds int err; 11321da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 11331da177e4SLinus Torvalds 11341da177e4SLinus Torvalds while (*name=='/') 11351da177e4SLinus Torvalds name++; 11361da177e4SLinus Torvalds if (!*name) 11371da177e4SLinus Torvalds goto return_reval; 11381da177e4SLinus Torvalds 11391da177e4SLinus Torvalds if (nd->depth) 1140f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 11411da177e4SLinus Torvalds 11421da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 11431da177e4SLinus Torvalds for(;;) { 114431e6b01fSNick Piggin struct inode *inode; 11451da177e4SLinus Torvalds unsigned long hash; 11461da177e4SLinus Torvalds struct qstr this; 11471da177e4SLinus Torvalds unsigned int c; 11481da177e4SLinus Torvalds 1149cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 115031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 1151b74c79e9SNick Piggin err = exec_permission(nd->inode, IPERM_FLAG_RCU); 115231e6b01fSNick Piggin if (err == -ECHILD) { 115331e6b01fSNick Piggin if (nameidata_drop_rcu(nd)) 115431e6b01fSNick Piggin return -ECHILD; 115531e6b01fSNick Piggin goto exec_again; 115631e6b01fSNick Piggin } 115731e6b01fSNick Piggin } else { 115831e6b01fSNick Piggin exec_again: 1159b74c79e9SNick Piggin err = exec_permission(nd->inode, 0); 116031e6b01fSNick Piggin } 11611da177e4SLinus Torvalds if (err) 11621da177e4SLinus Torvalds break; 11631da177e4SLinus Torvalds 11641da177e4SLinus Torvalds this.name = name; 11651da177e4SLinus Torvalds c = *(const unsigned char *)name; 11661da177e4SLinus Torvalds 11671da177e4SLinus Torvalds hash = init_name_hash(); 11681da177e4SLinus Torvalds do { 11691da177e4SLinus Torvalds name++; 11701da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 11711da177e4SLinus Torvalds c = *(const unsigned char *)name; 11721da177e4SLinus Torvalds } while (c && (c != '/')); 11731da177e4SLinus Torvalds this.len = name - (const char *) this.name; 11741da177e4SLinus Torvalds this.hash = end_name_hash(hash); 11751da177e4SLinus Torvalds 11761da177e4SLinus Torvalds /* remove trailing slashes? */ 11771da177e4SLinus Torvalds if (!c) 11781da177e4SLinus Torvalds goto last_component; 11791da177e4SLinus Torvalds while (*++name == '/'); 11801da177e4SLinus Torvalds if (!*name) 11811da177e4SLinus Torvalds goto last_with_slashes; 11821da177e4SLinus Torvalds 11831da177e4SLinus Torvalds /* 11841da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 11851da177e4SLinus Torvalds * to be able to know about the current root directory and 11861da177e4SLinus Torvalds * parent relationships. 11871da177e4SLinus Torvalds */ 11881da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 11891da177e4SLinus Torvalds default: 11901da177e4SLinus Torvalds break; 11911da177e4SLinus Torvalds case 2: 11921da177e4SLinus Torvalds if (this.name[1] != '.') 11931da177e4SLinus Torvalds break; 119431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 119531e6b01fSNick Piggin if (follow_dotdot_rcu(nd)) 119631e6b01fSNick Piggin return -ECHILD; 119731e6b01fSNick Piggin } else 119858c465ebSAl Viro follow_dotdot(nd); 11991da177e4SLinus Torvalds /* fallthrough */ 12001da177e4SLinus Torvalds case 1: 12011da177e4SLinus Torvalds continue; 12021da177e4SLinus Torvalds } 12031da177e4SLinus Torvalds /* This does the actual lookups.. */ 120431e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 12051da177e4SLinus Torvalds if (err) 12061da177e4SLinus Torvalds break; 12071da177e4SLinus Torvalds err = -ENOENT; 12081da177e4SLinus Torvalds if (!inode) 12091da177e4SLinus Torvalds goto out_dput; 12101da177e4SLinus Torvalds 12111da177e4SLinus Torvalds if (inode->i_op->follow_link) { 121231e6b01fSNick Piggin /* We commonly drop rcu-walk here */ 121331e6b01fSNick Piggin if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry)) 121431e6b01fSNick Piggin return -ECHILD; 121531e6b01fSNick Piggin BUG_ON(inode != next.dentry->d_inode); 121690ebe565SAl Viro err = do_follow_link(&next, nd); 12171da177e4SLinus Torvalds if (err) 12181da177e4SLinus Torvalds goto return_err; 121931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12201da177e4SLinus Torvalds err = -ENOENT; 122131e6b01fSNick Piggin if (!nd->inode) 12221da177e4SLinus Torvalds break; 122331e6b01fSNick Piggin } else { 122409dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 122531e6b01fSNick Piggin nd->inode = inode; 122631e6b01fSNick Piggin } 12271da177e4SLinus Torvalds err = -ENOTDIR; 122831e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 12291da177e4SLinus Torvalds break; 12301da177e4SLinus Torvalds continue; 12311da177e4SLinus Torvalds /* here ends the main loop */ 12321da177e4SLinus Torvalds 12331da177e4SLinus Torvalds last_with_slashes: 12341da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 12351da177e4SLinus Torvalds last_component: 1236f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1237f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 12381da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 12391da177e4SLinus Torvalds goto lookup_parent; 12401da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 12411da177e4SLinus Torvalds default: 12421da177e4SLinus Torvalds break; 12431da177e4SLinus Torvalds case 2: 12441da177e4SLinus Torvalds if (this.name[1] != '.') 12451da177e4SLinus Torvalds break; 124631e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 124731e6b01fSNick Piggin if (follow_dotdot_rcu(nd)) 124831e6b01fSNick Piggin return -ECHILD; 124931e6b01fSNick Piggin } else 125058c465ebSAl Viro follow_dotdot(nd); 12511da177e4SLinus Torvalds /* fallthrough */ 12521da177e4SLinus Torvalds case 1: 12531da177e4SLinus Torvalds goto return_reval; 12541da177e4SLinus Torvalds } 125531e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 12561da177e4SLinus Torvalds if (err) 12571da177e4SLinus Torvalds break; 1258ac278a9cSAl Viro if (follow_on_final(inode, lookup_flags)) { 125931e6b01fSNick Piggin if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry)) 126031e6b01fSNick Piggin return -ECHILD; 126131e6b01fSNick Piggin BUG_ON(inode != next.dentry->d_inode); 126290ebe565SAl Viro err = do_follow_link(&next, nd); 12631da177e4SLinus Torvalds if (err) 12641da177e4SLinus Torvalds goto return_err; 126531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 126631e6b01fSNick Piggin } else { 126709dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 126831e6b01fSNick Piggin nd->inode = inode; 126931e6b01fSNick Piggin } 12701da177e4SLinus Torvalds err = -ENOENT; 127131e6b01fSNick Piggin if (!nd->inode) 12721da177e4SLinus Torvalds break; 12731da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 12741da177e4SLinus Torvalds err = -ENOTDIR; 127531e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 12761da177e4SLinus Torvalds break; 12771da177e4SLinus Torvalds } 12781da177e4SLinus Torvalds goto return_base; 12791da177e4SLinus Torvalds lookup_parent: 12801da177e4SLinus Torvalds nd->last = this; 12811da177e4SLinus Torvalds nd->last_type = LAST_NORM; 12821da177e4SLinus Torvalds if (this.name[0] != '.') 12831da177e4SLinus Torvalds goto return_base; 12841da177e4SLinus Torvalds if (this.len == 1) 12851da177e4SLinus Torvalds nd->last_type = LAST_DOT; 12861da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 12871da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 12881da177e4SLinus Torvalds else 12891da177e4SLinus Torvalds goto return_base; 12901da177e4SLinus Torvalds return_reval: 12911da177e4SLinus Torvalds /* 12921da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 12931da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 12941da177e4SLinus Torvalds */ 1295fb045adbSNick Piggin if (need_reval_dot(nd->path.dentry)) { 12961da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 129734286d66SNick Piggin err = d_revalidate(nd->path.dentry, nd); 129834286d66SNick Piggin if (!err) 129934286d66SNick Piggin err = -ESTALE; 130034286d66SNick Piggin if (err < 0) 13011da177e4SLinus Torvalds break; 13021da177e4SLinus Torvalds } 13031da177e4SLinus Torvalds return_base: 130431e6b01fSNick Piggin if (nameidata_drop_rcu_last_maybe(nd)) 130531e6b01fSNick Piggin return -ECHILD; 13061da177e4SLinus Torvalds return 0; 13071da177e4SLinus Torvalds out_dput: 130831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) 13091d957f9bSJan Blunck path_put_conditional(&next, nd); 13101da177e4SLinus Torvalds break; 13111da177e4SLinus Torvalds } 131231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) 13131d957f9bSJan Blunck path_put(&nd->path); 13141da177e4SLinus Torvalds return_err: 13151da177e4SLinus Torvalds return err; 13161da177e4SLinus Torvalds } 13171da177e4SLinus Torvalds 131831e6b01fSNick Piggin static inline int path_walk_rcu(const char *name, struct nameidata *nd) 131931e6b01fSNick Piggin { 132031e6b01fSNick Piggin current->total_link_count = 0; 132131e6b01fSNick Piggin 132231e6b01fSNick Piggin return link_path_walk(name, nd); 132331e6b01fSNick Piggin } 132431e6b01fSNick Piggin 132531e6b01fSNick Piggin static inline int path_walk_simple(const char *name, struct nameidata *nd) 132631e6b01fSNick Piggin { 132731e6b01fSNick Piggin current->total_link_count = 0; 132831e6b01fSNick Piggin 132931e6b01fSNick Piggin return link_path_walk(name, nd); 133031e6b01fSNick Piggin } 133131e6b01fSNick Piggin 1332fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 13331da177e4SLinus Torvalds { 13346de88d72SAl Viro struct path save = nd->path; 13356de88d72SAl Viro int result; 13366de88d72SAl Viro 13371da177e4SLinus Torvalds current->total_link_count = 0; 13386de88d72SAl Viro 13396de88d72SAl Viro /* make sure the stuff we saved doesn't go away */ 13406de88d72SAl Viro path_get(&save); 13416de88d72SAl Viro 13426de88d72SAl Viro result = link_path_walk(name, nd); 13436de88d72SAl Viro if (result == -ESTALE) { 13446de88d72SAl Viro /* nd->path had been dropped */ 13456de88d72SAl Viro current->total_link_count = 0; 13466de88d72SAl Viro nd->path = save; 13476de88d72SAl Viro path_get(&nd->path); 13486de88d72SAl Viro nd->flags |= LOOKUP_REVAL; 13496de88d72SAl Viro result = link_path_walk(name, nd); 13506de88d72SAl Viro } 13516de88d72SAl Viro 13526de88d72SAl Viro path_put(&save); 13536de88d72SAl Viro 13546de88d72SAl Viro return result; 13551da177e4SLinus Torvalds } 13561da177e4SLinus Torvalds 135731e6b01fSNick Piggin static void path_finish_rcu(struct nameidata *nd) 135831e6b01fSNick Piggin { 135931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 136031e6b01fSNick Piggin /* RCU dangling. Cancel it. */ 136131e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 136231e6b01fSNick Piggin nd->root.mnt = NULL; 136331e6b01fSNick Piggin rcu_read_unlock(); 136431e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 136531e6b01fSNick Piggin } 136631e6b01fSNick Piggin if (nd->file) 136731e6b01fSNick Piggin fput(nd->file); 136831e6b01fSNick Piggin } 136931e6b01fSNick Piggin 137031e6b01fSNick Piggin static int path_init_rcu(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 137131e6b01fSNick Piggin { 137231e6b01fSNick Piggin int retval = 0; 137331e6b01fSNick Piggin int fput_needed; 137431e6b01fSNick Piggin struct file *file; 137531e6b01fSNick Piggin 137631e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 137731e6b01fSNick Piggin nd->flags = flags | LOOKUP_RCU; 137831e6b01fSNick Piggin nd->depth = 0; 137931e6b01fSNick Piggin nd->root.mnt = NULL; 138031e6b01fSNick Piggin nd->file = NULL; 138131e6b01fSNick Piggin 138231e6b01fSNick Piggin if (*name=='/') { 138331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1384c28cc364SNick Piggin unsigned seq; 138531e6b01fSNick Piggin 138631e6b01fSNick Piggin br_read_lock(vfsmount_lock); 138731e6b01fSNick Piggin rcu_read_lock(); 138831e6b01fSNick Piggin 1389c28cc364SNick Piggin do { 1390c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 139131e6b01fSNick Piggin nd->root = fs->root; 139231e6b01fSNick Piggin nd->path = nd->root; 1393c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1394c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 139531e6b01fSNick Piggin 139631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 139731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1398c28cc364SNick Piggin unsigned seq; 139931e6b01fSNick Piggin 140031e6b01fSNick Piggin br_read_lock(vfsmount_lock); 140131e6b01fSNick Piggin rcu_read_lock(); 140231e6b01fSNick Piggin 1403c28cc364SNick Piggin do { 1404c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 140531e6b01fSNick Piggin nd->path = fs->pwd; 1406c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1407c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1408c28cc364SNick Piggin 140931e6b01fSNick Piggin } else { 141031e6b01fSNick Piggin struct dentry *dentry; 141131e6b01fSNick Piggin 141231e6b01fSNick Piggin file = fget_light(dfd, &fput_needed); 141331e6b01fSNick Piggin retval = -EBADF; 141431e6b01fSNick Piggin if (!file) 141531e6b01fSNick Piggin goto out_fail; 141631e6b01fSNick Piggin 141731e6b01fSNick Piggin dentry = file->f_path.dentry; 141831e6b01fSNick Piggin 141931e6b01fSNick Piggin retval = -ENOTDIR; 142031e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 142131e6b01fSNick Piggin goto fput_fail; 142231e6b01fSNick Piggin 142331e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 142431e6b01fSNick Piggin if (retval) 142531e6b01fSNick Piggin goto fput_fail; 142631e6b01fSNick Piggin 142731e6b01fSNick Piggin nd->path = file->f_path; 142831e6b01fSNick Piggin if (fput_needed) 142931e6b01fSNick Piggin nd->file = file; 143031e6b01fSNick Piggin 1431c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 143231e6b01fSNick Piggin br_read_lock(vfsmount_lock); 143331e6b01fSNick Piggin rcu_read_lock(); 143431e6b01fSNick Piggin } 143531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 143631e6b01fSNick Piggin return 0; 143731e6b01fSNick Piggin 143831e6b01fSNick Piggin fput_fail: 143931e6b01fSNick Piggin fput_light(file, fput_needed); 144031e6b01fSNick Piggin out_fail: 144131e6b01fSNick Piggin return retval; 144231e6b01fSNick Piggin } 144331e6b01fSNick Piggin 14449b4a9b14SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 14451da177e4SLinus Torvalds { 1446ea3834d9SPrasanna Meda int retval = 0; 1447170aa3d0SUlrich Drepper int fput_needed; 1448170aa3d0SUlrich Drepper struct file *file; 14491da177e4SLinus Torvalds 14501da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 14511da177e4SLinus Torvalds nd->flags = flags; 14521da177e4SLinus Torvalds nd->depth = 0; 14532a737871SAl Viro nd->root.mnt = NULL; 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds if (*name=='/') { 14562a737871SAl Viro set_root(nd); 14572a737871SAl Viro nd->path = nd->root; 14582a737871SAl Viro path_get(&nd->root); 14595590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1460f7ad3c6bSMiklos Szeredi get_fs_pwd(current->fs, &nd->path); 14615590ff0dSUlrich Drepper } else { 14625590ff0dSUlrich Drepper struct dentry *dentry; 14635590ff0dSUlrich Drepper 14645590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 14655590ff0dSUlrich Drepper retval = -EBADF; 1466170aa3d0SUlrich Drepper if (!file) 14676d09bb62STrond Myklebust goto out_fail; 14685590ff0dSUlrich Drepper 14690f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 14705590ff0dSUlrich Drepper 14715590ff0dSUlrich Drepper retval = -ENOTDIR; 1472170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 14736d09bb62STrond Myklebust goto fput_fail; 14745590ff0dSUlrich Drepper 14755590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1476170aa3d0SUlrich Drepper if (retval) 14776d09bb62STrond Myklebust goto fput_fail; 14785590ff0dSUlrich Drepper 14795dd784d0SJan Blunck nd->path = file->f_path; 14805dd784d0SJan Blunck path_get(&file->f_path); 14815590ff0dSUlrich Drepper 14825590ff0dSUlrich Drepper fput_light(file, fput_needed); 14831da177e4SLinus Torvalds } 148431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14859b4a9b14SAl Viro return 0; 14862dfdd266SJosef 'Jeff' Sipek 14879b4a9b14SAl Viro fput_fail: 14889b4a9b14SAl Viro fput_light(file, fput_needed); 14899b4a9b14SAl Viro out_fail: 14909b4a9b14SAl Viro return retval; 14919b4a9b14SAl Viro } 14929b4a9b14SAl Viro 14939b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 14949b4a9b14SAl Viro static int do_path_lookup(int dfd, const char *name, 14959b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 14969b4a9b14SAl Viro { 149731e6b01fSNick Piggin int retval; 149831e6b01fSNick Piggin 149931e6b01fSNick Piggin /* 150031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 150131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 150231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 150331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 150431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 150531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 150631e6b01fSNick Piggin * analogue, foo_rcu(). 150731e6b01fSNick Piggin * 150831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 150931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 151031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 151131e6b01fSNick Piggin * be able to complete). 151231e6b01fSNick Piggin */ 151331e6b01fSNick Piggin retval = path_init_rcu(dfd, name, flags, nd); 151431e6b01fSNick Piggin if (unlikely(retval)) 151531e6b01fSNick Piggin return retval; 151631e6b01fSNick Piggin retval = path_walk_rcu(name, nd); 151731e6b01fSNick Piggin path_finish_rcu(nd); 15182a737871SAl Viro if (nd->root.mnt) { 15192a737871SAl Viro path_put(&nd->root); 15202a737871SAl Viro nd->root.mnt = NULL; 15212a737871SAl Viro } 152231e6b01fSNick Piggin 152331e6b01fSNick Piggin if (unlikely(retval == -ECHILD || retval == -ESTALE)) { 152431e6b01fSNick Piggin /* slower, locked walk */ 152531e6b01fSNick Piggin if (retval == -ESTALE) 152631e6b01fSNick Piggin flags |= LOOKUP_REVAL; 152731e6b01fSNick Piggin retval = path_init(dfd, name, flags, nd); 152831e6b01fSNick Piggin if (unlikely(retval)) 152931e6b01fSNick Piggin return retval; 153031e6b01fSNick Piggin retval = path_walk(name, nd); 153131e6b01fSNick Piggin if (nd->root.mnt) { 153231e6b01fSNick Piggin path_put(&nd->root); 153331e6b01fSNick Piggin nd->root.mnt = NULL; 153431e6b01fSNick Piggin } 153531e6b01fSNick Piggin } 153631e6b01fSNick Piggin 153731e6b01fSNick Piggin if (likely(!retval)) { 153831e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 153931e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 154031e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 154131e6b01fSNick Piggin } 154231e6b01fSNick Piggin } 154331e6b01fSNick Piggin 1544170aa3d0SUlrich Drepper return retval; 15451da177e4SLinus Torvalds } 15461da177e4SLinus Torvalds 1547fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 15485590ff0dSUlrich Drepper struct nameidata *nd) 15495590ff0dSUlrich Drepper { 15505590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 15515590ff0dSUlrich Drepper } 15525590ff0dSUlrich Drepper 1553d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1554d1811465SAl Viro { 1555d1811465SAl Viro struct nameidata nd; 1556d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1557d1811465SAl Viro if (!res) 1558d1811465SAl Viro *path = nd.path; 1559d1811465SAl Viro return res; 1560d1811465SAl Viro } 1561d1811465SAl Viro 156216f18200SJosef 'Jeff' Sipek /** 156316f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 156416f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 156516f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 156616f18200SJosef 'Jeff' Sipek * @name: pointer to file name 156716f18200SJosef 'Jeff' Sipek * @flags: lookup flags 156816f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 156916f18200SJosef 'Jeff' Sipek */ 157016f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 157116f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 157216f18200SJosef 'Jeff' Sipek struct nameidata *nd) 157316f18200SJosef 'Jeff' Sipek { 157416f18200SJosef 'Jeff' Sipek int retval; 157516f18200SJosef 'Jeff' Sipek 157616f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 157716f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 157816f18200SJosef 'Jeff' Sipek nd->flags = flags; 157916f18200SJosef 'Jeff' Sipek nd->depth = 0; 158016f18200SJosef 'Jeff' Sipek 1581c8e7f449SJan Blunck nd->path.dentry = dentry; 1582c8e7f449SJan Blunck nd->path.mnt = mnt; 1583c8e7f449SJan Blunck path_get(&nd->path); 15845b857119SAl Viro nd->root = nd->path; 15855b857119SAl Viro path_get(&nd->root); 158631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 158716f18200SJosef 'Jeff' Sipek 158816f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 15894ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 159031e6b01fSNick Piggin nd->inode)) 15914ac91378SJan Blunck audit_inode(name, nd->path.dentry); 159216f18200SJosef 'Jeff' Sipek 15932a737871SAl Viro path_put(&nd->root); 15942a737871SAl Viro nd->root.mnt = NULL; 159516f18200SJosef 'Jeff' Sipek 15962a737871SAl Viro return retval; 159716f18200SJosef 'Jeff' Sipek } 159816f18200SJosef 'Jeff' Sipek 1599eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1600eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16011da177e4SLinus Torvalds { 160281fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16031da177e4SLinus Torvalds struct dentry *dentry; 16041da177e4SLinus Torvalds int err; 16051da177e4SLinus Torvalds 1606b74c79e9SNick Piggin err = exec_permission(inode, 0); 160781fca444SChristoph Hellwig if (err) 160881fca444SChristoph Hellwig return ERR_PTR(err); 16091da177e4SLinus Torvalds 16101da177e4SLinus Torvalds /* 16111da177e4SLinus Torvalds * See if the low-level filesystem might want 16121da177e4SLinus Torvalds * to use its own hash.. 16131da177e4SLinus Torvalds */ 1614fb045adbSNick Piggin if (base->d_flags & DCACHE_OP_HASH) { 1615b1e6a015SNick Piggin err = base->d_op->d_hash(base, inode, name); 16161da177e4SLinus Torvalds dentry = ERR_PTR(err); 16171da177e4SLinus Torvalds if (err < 0) 16181da177e4SLinus Torvalds goto out; 16191da177e4SLinus Torvalds } 16201da177e4SLinus Torvalds 1621b04f784eSNick Piggin /* 1622b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1623b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1624b04f784eSNick Piggin * a double lookup. 16256e6b1bd1SAl Viro */ 16266e6b1bd1SAl Viro dentry = d_lookup(base, name); 16276e6b1bd1SAl Viro 1628fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 16296e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 16306e6b1bd1SAl Viro 16311da177e4SLinus Torvalds if (!dentry) 1632baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 16331da177e4SLinus Torvalds out: 16341da177e4SLinus Torvalds return dentry; 16351da177e4SLinus Torvalds } 16361da177e4SLinus Torvalds 1637057f6c01SJames Morris /* 1638057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1639057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1640057f6c01SJames Morris * SMP-safe. 1641057f6c01SJames Morris */ 1642a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 16431da177e4SLinus Torvalds { 16444ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 16451da177e4SLinus Torvalds } 16461da177e4SLinus Torvalds 1647eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1648eead1911SChristoph Hellwig struct dentry *base, int len) 16491da177e4SLinus Torvalds { 16501da177e4SLinus Torvalds unsigned long hash; 16511da177e4SLinus Torvalds unsigned int c; 16521da177e4SLinus Torvalds 1653057f6c01SJames Morris this->name = name; 1654057f6c01SJames Morris this->len = len; 16551da177e4SLinus Torvalds if (!len) 1656057f6c01SJames Morris return -EACCES; 16571da177e4SLinus Torvalds 16581da177e4SLinus Torvalds hash = init_name_hash(); 16591da177e4SLinus Torvalds while (len--) { 16601da177e4SLinus Torvalds c = *(const unsigned char *)name++; 16611da177e4SLinus Torvalds if (c == '/' || c == '\0') 1662057f6c01SJames Morris return -EACCES; 16631da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 16641da177e4SLinus Torvalds } 1665057f6c01SJames Morris this->hash = end_name_hash(hash); 1666057f6c01SJames Morris return 0; 1667057f6c01SJames Morris } 16681da177e4SLinus Torvalds 1669eead1911SChristoph Hellwig /** 1670a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1671eead1911SChristoph Hellwig * @name: pathname component to lookup 1672eead1911SChristoph Hellwig * @base: base directory to lookup from 1673eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1674eead1911SChristoph Hellwig * 1675a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1676a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1677eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1678eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1679eead1911SChristoph Hellwig */ 1680057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1681057f6c01SJames Morris { 1682057f6c01SJames Morris int err; 1683057f6c01SJames Morris struct qstr this; 1684057f6c01SJames Morris 16852f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 16862f9092e1SDavid Woodhouse 1687057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1688057f6c01SJames Morris if (err) 1689057f6c01SJames Morris return ERR_PTR(err); 1690eead1911SChristoph Hellwig 169149705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1692057f6c01SJames Morris } 1693057f6c01SJames Morris 16942d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 16952d8f3038SAl Viro struct path *path) 16961da177e4SLinus Torvalds { 16972d8f3038SAl Viro struct nameidata nd; 16981da177e4SLinus Torvalds char *tmp = getname(name); 16991da177e4SLinus Torvalds int err = PTR_ERR(tmp); 17001da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 17012d8f3038SAl Viro 17022d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 17032d8f3038SAl Viro 17042d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 17051da177e4SLinus Torvalds putname(tmp); 17062d8f3038SAl Viro if (!err) 17072d8f3038SAl Viro *path = nd.path; 17081da177e4SLinus Torvalds } 17091da177e4SLinus Torvalds return err; 17101da177e4SLinus Torvalds } 17111da177e4SLinus Torvalds 17122ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 17132ad94ae6SAl Viro struct nameidata *nd, char **name) 17142ad94ae6SAl Viro { 17152ad94ae6SAl Viro char *s = getname(path); 17162ad94ae6SAl Viro int error; 17172ad94ae6SAl Viro 17182ad94ae6SAl Viro if (IS_ERR(s)) 17192ad94ae6SAl Viro return PTR_ERR(s); 17202ad94ae6SAl Viro 17212ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 17222ad94ae6SAl Viro if (error) 17232ad94ae6SAl Viro putname(s); 17242ad94ae6SAl Viro else 17252ad94ae6SAl Viro *name = s; 17262ad94ae6SAl Viro 17272ad94ae6SAl Viro return error; 17282ad94ae6SAl Viro } 17292ad94ae6SAl Viro 17301da177e4SLinus Torvalds /* 17311da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 17321da177e4SLinus Torvalds * minimal. 17331da177e4SLinus Torvalds */ 17341da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 17351da177e4SLinus Torvalds { 1736da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1737da9592edSDavid Howells 17381da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 17391da177e4SLinus Torvalds return 0; 1740da9592edSDavid Howells if (inode->i_uid == fsuid) 17411da177e4SLinus Torvalds return 0; 1742da9592edSDavid Howells if (dir->i_uid == fsuid) 17431da177e4SLinus Torvalds return 0; 17441da177e4SLinus Torvalds return !capable(CAP_FOWNER); 17451da177e4SLinus Torvalds } 17461da177e4SLinus Torvalds 17471da177e4SLinus Torvalds /* 17481da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 17491da177e4SLinus Torvalds * whether the type of victim is right. 17501da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 17511da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 17521da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 17531da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 17541da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 17551da177e4SLinus Torvalds * a. be owner of dir, or 17561da177e4SLinus Torvalds * b. be owner of victim, or 17571da177e4SLinus Torvalds * c. have CAP_FOWNER capability 17581da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 17591da177e4SLinus Torvalds * links pointing to it. 17601da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 17611da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 17621da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 17631da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 17641da177e4SLinus Torvalds * nfs_async_unlink(). 17651da177e4SLinus Torvalds */ 1766858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 17671da177e4SLinus Torvalds { 17681da177e4SLinus Torvalds int error; 17691da177e4SLinus Torvalds 17701da177e4SLinus Torvalds if (!victim->d_inode) 17711da177e4SLinus Torvalds return -ENOENT; 17721da177e4SLinus Torvalds 17731da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1774cccc6bbaSAl Viro audit_inode_child(victim, dir); 17751da177e4SLinus Torvalds 1776f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 17771da177e4SLinus Torvalds if (error) 17781da177e4SLinus Torvalds return error; 17791da177e4SLinus Torvalds if (IS_APPEND(dir)) 17801da177e4SLinus Torvalds return -EPERM; 17811da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1782f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 17831da177e4SLinus Torvalds return -EPERM; 17841da177e4SLinus Torvalds if (isdir) { 17851da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 17861da177e4SLinus Torvalds return -ENOTDIR; 17871da177e4SLinus Torvalds if (IS_ROOT(victim)) 17881da177e4SLinus Torvalds return -EBUSY; 17891da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 17901da177e4SLinus Torvalds return -EISDIR; 17911da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 17921da177e4SLinus Torvalds return -ENOENT; 17931da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 17941da177e4SLinus Torvalds return -EBUSY; 17951da177e4SLinus Torvalds return 0; 17961da177e4SLinus Torvalds } 17971da177e4SLinus Torvalds 17981da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 17991da177e4SLinus Torvalds * dir. 18001da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 18011da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 18021da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 18031da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 18041da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 18051da177e4SLinus Torvalds */ 1806a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 18071da177e4SLinus Torvalds { 18081da177e4SLinus Torvalds if (child->d_inode) 18091da177e4SLinus Torvalds return -EEXIST; 18101da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18111da177e4SLinus Torvalds return -ENOENT; 1812f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 18131da177e4SLinus Torvalds } 18141da177e4SLinus Torvalds 18151da177e4SLinus Torvalds /* 18161da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 18171da177e4SLinus Torvalds */ 18181da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 18191da177e4SLinus Torvalds { 18201da177e4SLinus Torvalds struct dentry *p; 18211da177e4SLinus Torvalds 18221da177e4SLinus Torvalds if (p1 == p2) { 1823f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 18241da177e4SLinus Torvalds return NULL; 18251da177e4SLinus Torvalds } 18261da177e4SLinus Torvalds 1827a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18281da177e4SLinus Torvalds 1829e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1830e2761a11SOGAWA Hirofumi if (p) { 1831f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1832f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 18331da177e4SLinus Torvalds return p; 18341da177e4SLinus Torvalds } 18351da177e4SLinus Torvalds 1836e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1837e2761a11SOGAWA Hirofumi if (p) { 1838f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1839f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 18401da177e4SLinus Torvalds return p; 18411da177e4SLinus Torvalds } 18421da177e4SLinus Torvalds 1843f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1844f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 18451da177e4SLinus Torvalds return NULL; 18461da177e4SLinus Torvalds } 18471da177e4SLinus Torvalds 18481da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 18491da177e4SLinus Torvalds { 18501b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 18511da177e4SLinus Torvalds if (p1 != p2) { 18521b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1853a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18541da177e4SLinus Torvalds } 18551da177e4SLinus Torvalds } 18561da177e4SLinus Torvalds 18571da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 18581da177e4SLinus Torvalds struct nameidata *nd) 18591da177e4SLinus Torvalds { 1860a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 18611da177e4SLinus Torvalds 18621da177e4SLinus Torvalds if (error) 18631da177e4SLinus Torvalds return error; 18641da177e4SLinus Torvalds 1865acfa4380SAl Viro if (!dir->i_op->create) 18661da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 18671da177e4SLinus Torvalds mode &= S_IALLUGO; 18681da177e4SLinus Torvalds mode |= S_IFREG; 18691da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 18701da177e4SLinus Torvalds if (error) 18711da177e4SLinus Torvalds return error; 18721da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1873a74574aaSStephen Smalley if (!error) 1874f38aa942SAmy Griffis fsnotify_create(dir, dentry); 18751da177e4SLinus Torvalds return error; 18761da177e4SLinus Torvalds } 18771da177e4SLinus Torvalds 18783fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 18791da177e4SLinus Torvalds { 18803fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 18811da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 18821da177e4SLinus Torvalds int error; 18831da177e4SLinus Torvalds 18841da177e4SLinus Torvalds if (!inode) 18851da177e4SLinus Torvalds return -ENOENT; 18861da177e4SLinus Torvalds 1887c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1888c8fe8f30SChristoph Hellwig case S_IFLNK: 18891da177e4SLinus Torvalds return -ELOOP; 1890c8fe8f30SChristoph Hellwig case S_IFDIR: 1891c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 18921da177e4SLinus Torvalds return -EISDIR; 1893c8fe8f30SChristoph Hellwig break; 1894c8fe8f30SChristoph Hellwig case S_IFBLK: 1895c8fe8f30SChristoph Hellwig case S_IFCHR: 18963fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 18971da177e4SLinus Torvalds return -EACCES; 1898c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1899c8fe8f30SChristoph Hellwig case S_IFIFO: 1900c8fe8f30SChristoph Hellwig case S_IFSOCK: 19011da177e4SLinus Torvalds flag &= ~O_TRUNC; 1902c8fe8f30SChristoph Hellwig break; 19034a3fd211SDave Hansen } 1904b41572e9SDave Hansen 19053fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1906b41572e9SDave Hansen if (error) 1907b41572e9SDave Hansen return error; 19086146f0d5SMimi Zohar 19091da177e4SLinus Torvalds /* 19101da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 19111da177e4SLinus Torvalds */ 19121da177e4SLinus Torvalds if (IS_APPEND(inode)) { 19138737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 19147715b521SAl Viro return -EPERM; 19151da177e4SLinus Torvalds if (flag & O_TRUNC) 19167715b521SAl Viro return -EPERM; 19171da177e4SLinus Torvalds } 19181da177e4SLinus Torvalds 19191da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 19207715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 19217715b521SAl Viro return -EPERM; 19221da177e4SLinus Torvalds 19231da177e4SLinus Torvalds /* 19241da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 19251da177e4SLinus Torvalds */ 1926b65a9cfcSAl Viro return break_lease(inode, flag); 19277715b521SAl Viro } 19287715b521SAl Viro 19297715b521SAl Viro static int handle_truncate(struct path *path) 19307715b521SAl Viro { 19317715b521SAl Viro struct inode *inode = path->dentry->d_inode; 19327715b521SAl Viro int error = get_write_access(inode); 19331da177e4SLinus Torvalds if (error) 19347715b521SAl Viro return error; 19351da177e4SLinus Torvalds /* 19361da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 19371da177e4SLinus Torvalds */ 19381da177e4SLinus Torvalds error = locks_verify_locked(inode); 1939be6d3e56SKentaro Takeda if (!error) 1940ea0d3ab2STetsuo Handa error = security_path_truncate(path); 19411da177e4SLinus Torvalds if (!error) { 19427715b521SAl Viro error = do_truncate(path->dentry, 0, 1943d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1944d139d7ffSMiklos Szeredi NULL); 19451da177e4SLinus Torvalds } 19461da177e4SLinus Torvalds put_write_access(inode); 1947acd0c935SMimi Zohar return error; 19481da177e4SLinus Torvalds } 19491da177e4SLinus Torvalds 1950d57999e1SDave Hansen /* 1951d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1952d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1953d57999e1SDave Hansen * what get passed to sys_open(). 1954d57999e1SDave Hansen */ 1955d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 19568737c930SAl Viro int open_flag, int mode) 1957aab520e2SDave Hansen { 1958aab520e2SDave Hansen int error; 19594ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1960aab520e2SDave Hansen 1961aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1962ce3b0f8dSAl Viro mode &= ~current_umask(); 1963be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1964be6d3e56SKentaro Takeda if (error) 1965be6d3e56SKentaro Takeda goto out_unlock; 1966aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1967be6d3e56SKentaro Takeda out_unlock: 1968aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 19694ac91378SJan Blunck dput(nd->path.dentry); 19704ac91378SJan Blunck nd->path.dentry = path->dentry; 197131e6b01fSNick Piggin 1972aab520e2SDave Hansen if (error) 1973aab520e2SDave Hansen return error; 1974aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 19758737c930SAl Viro return may_open(&nd->path, 0, open_flag & ~O_TRUNC); 1976aab520e2SDave Hansen } 1977aab520e2SDave Hansen 19781da177e4SLinus Torvalds /* 1979d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1980d57999e1SDave Hansen * 00 - read-only 1981d57999e1SDave Hansen * 01 - write-only 1982d57999e1SDave Hansen * 10 - read-write 1983d57999e1SDave Hansen * 11 - special 1984d57999e1SDave Hansen * it is changed into 1985d57999e1SDave Hansen * 00 - no permissions needed 1986d57999e1SDave Hansen * 01 - read-permission 1987d57999e1SDave Hansen * 10 - write-permission 1988d57999e1SDave Hansen * 11 - read-write 1989d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1990d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1991d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1992d57999e1SDave Hansen * later). 1993d57999e1SDave Hansen * 1994d57999e1SDave Hansen */ 1995d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1996d57999e1SDave Hansen { 1997d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1998d57999e1SDave Hansen flag++; 1999d57999e1SDave Hansen return flag; 2000d57999e1SDave Hansen } 2001d57999e1SDave Hansen 20027715b521SAl Viro static int open_will_truncate(int flag, struct inode *inode) 20034a3fd211SDave Hansen { 2004d57999e1SDave Hansen /* 20054a3fd211SDave Hansen * We'll never write to the fs underlying 20064a3fd211SDave Hansen * a device file. 20074a3fd211SDave Hansen */ 20084a3fd211SDave Hansen if (special_file(inode->i_mode)) 20094a3fd211SDave Hansen return 0; 20104a3fd211SDave Hansen return (flag & O_TRUNC); 20114a3fd211SDave Hansen } 20124a3fd211SDave Hansen 2013648fa861SAl Viro static struct file *finish_open(struct nameidata *nd, 20149a66179eSAl Viro int open_flag, int acc_mode) 2015648fa861SAl Viro { 2016648fa861SAl Viro struct file *filp; 2017648fa861SAl Viro int will_truncate; 2018648fa861SAl Viro int error; 2019648fa861SAl Viro 20209a66179eSAl Viro will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode); 2021648fa861SAl Viro if (will_truncate) { 2022648fa861SAl Viro error = mnt_want_write(nd->path.mnt); 2023648fa861SAl Viro if (error) 2024648fa861SAl Viro goto exit; 2025648fa861SAl Viro } 2026648fa861SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2027648fa861SAl Viro if (error) { 2028648fa861SAl Viro if (will_truncate) 2029648fa861SAl Viro mnt_drop_write(nd->path.mnt); 2030648fa861SAl Viro goto exit; 2031648fa861SAl Viro } 2032648fa861SAl Viro filp = nameidata_to_filp(nd); 2033648fa861SAl Viro if (!IS_ERR(filp)) { 2034648fa861SAl Viro error = ima_file_check(filp, acc_mode); 2035648fa861SAl Viro if (error) { 2036648fa861SAl Viro fput(filp); 2037648fa861SAl Viro filp = ERR_PTR(error); 2038648fa861SAl Viro } 2039648fa861SAl Viro } 2040648fa861SAl Viro if (!IS_ERR(filp)) { 2041648fa861SAl Viro if (will_truncate) { 2042648fa861SAl Viro error = handle_truncate(&nd->path); 2043648fa861SAl Viro if (error) { 2044648fa861SAl Viro fput(filp); 2045648fa861SAl Viro filp = ERR_PTR(error); 2046648fa861SAl Viro } 2047648fa861SAl Viro } 2048648fa861SAl Viro } 2049648fa861SAl Viro /* 2050648fa861SAl Viro * It is now safe to drop the mnt write 2051648fa861SAl Viro * because the filp has had a write taken 2052648fa861SAl Viro * on its behalf. 2053648fa861SAl Viro */ 2054648fa861SAl Viro if (will_truncate) 2055648fa861SAl Viro mnt_drop_write(nd->path.mnt); 2056d893f1bcSAl Viro path_put(&nd->path); 2057648fa861SAl Viro return filp; 2058648fa861SAl Viro 2059648fa861SAl Viro exit: 2060648fa861SAl Viro if (!IS_ERR(nd->intent.open.file)) 2061648fa861SAl Viro release_open_intent(nd); 2062648fa861SAl Viro path_put(&nd->path); 2063648fa861SAl Viro return ERR_PTR(error); 2064648fa861SAl Viro } 2065648fa861SAl Viro 206631e6b01fSNick Piggin /* 206731e6b01fSNick Piggin * Handle O_CREAT case for do_filp_open 206831e6b01fSNick Piggin */ 2069fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 20705b369df8SAl Viro int open_flag, int acc_mode, 20713e297b61SAl Viro int mode, const char *pathname) 2072fb1cc555SAl Viro { 2073a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2074fb1cc555SAl Viro struct file *filp; 20751f36f774SAl Viro int error = -EISDIR; 2076fb1cc555SAl Viro 20771f36f774SAl Viro switch (nd->last_type) { 20781f36f774SAl Viro case LAST_DOTDOT: 20791f36f774SAl Viro follow_dotdot(nd); 20801f36f774SAl Viro dir = nd->path.dentry; 2081176306f5SNeil Brown case LAST_DOT: 2082fb045adbSNick Piggin if (need_reval_dot(dir)) { 208334286d66SNick Piggin error = d_revalidate(nd->path.dentry, nd); 208434286d66SNick Piggin if (!error) 20851f36f774SAl Viro error = -ESTALE; 208634286d66SNick Piggin if (error < 0) 2087a2c36b45SAl Viro goto exit; 20881f36f774SAl Viro } 20891f36f774SAl Viro /* fallthrough */ 20901f36f774SAl Viro case LAST_ROOT: 20911f36f774SAl Viro goto exit; 20921f36f774SAl Viro case LAST_BIND: 20931f36f774SAl Viro audit_inode(pathname, dir); 20941f36f774SAl Viro goto ok; 20951f36f774SAl Viro } 2096a2c36b45SAl Viro 20971f36f774SAl Viro /* trailing slashes? */ 209831e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 20991f36f774SAl Viro goto exit; 21001f36f774SAl Viro 2101a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2102a1e28038SAl Viro 2103a1e28038SAl Viro path->dentry = lookup_hash(nd); 2104a1e28038SAl Viro path->mnt = nd->path.mnt; 2105a1e28038SAl Viro 2106fb1cc555SAl Viro error = PTR_ERR(path->dentry); 2107fb1cc555SAl Viro if (IS_ERR(path->dentry)) { 2108fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2109fb1cc555SAl Viro goto exit; 2110fb1cc555SAl Viro } 2111fb1cc555SAl Viro 2112fb1cc555SAl Viro if (IS_ERR(nd->intent.open.file)) { 2113fb1cc555SAl Viro error = PTR_ERR(nd->intent.open.file); 2114fb1cc555SAl Viro goto exit_mutex_unlock; 2115fb1cc555SAl Viro } 2116fb1cc555SAl Viro 2117fb1cc555SAl Viro /* Negative dentry, just create the file */ 2118fb1cc555SAl Viro if (!path->dentry->d_inode) { 2119fb1cc555SAl Viro /* 2120fb1cc555SAl Viro * This write is needed to ensure that a 2121fb1cc555SAl Viro * ro->rw transition does not occur between 2122fb1cc555SAl Viro * the time when the file is created and when 2123fb1cc555SAl Viro * a permanent write count is taken through 2124fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2125fb1cc555SAl Viro */ 2126fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2127fb1cc555SAl Viro if (error) 2128fb1cc555SAl Viro goto exit_mutex_unlock; 2129fb1cc555SAl Viro error = __open_namei_create(nd, path, open_flag, mode); 2130fb1cc555SAl Viro if (error) { 2131fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 2132fb1cc555SAl Viro goto exit; 2133fb1cc555SAl Viro } 2134fb1cc555SAl Viro filp = nameidata_to_filp(nd); 2135fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 2136d893f1bcSAl Viro path_put(&nd->path); 2137fb1cc555SAl Viro if (!IS_ERR(filp)) { 2138fb1cc555SAl Viro error = ima_file_check(filp, acc_mode); 2139fb1cc555SAl Viro if (error) { 2140fb1cc555SAl Viro fput(filp); 2141fb1cc555SAl Viro filp = ERR_PTR(error); 2142fb1cc555SAl Viro } 2143fb1cc555SAl Viro } 2144fb1cc555SAl Viro return filp; 2145fb1cc555SAl Viro } 2146fb1cc555SAl Viro 2147fb1cc555SAl Viro /* 2148fb1cc555SAl Viro * It already exists. 2149fb1cc555SAl Viro */ 2150fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2151fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2152fb1cc555SAl Viro 2153fb1cc555SAl Viro error = -EEXIST; 21545b369df8SAl Viro if (open_flag & O_EXCL) 2155fb1cc555SAl Viro goto exit_dput; 2156fb1cc555SAl Viro 2157fb1cc555SAl Viro if (__follow_mount(path)) { 2158fb1cc555SAl Viro error = -ELOOP; 21595b369df8SAl Viro if (open_flag & O_NOFOLLOW) 2160fb1cc555SAl Viro goto exit_dput; 2161fb1cc555SAl Viro } 2162fb1cc555SAl Viro 2163fb1cc555SAl Viro error = -ENOENT; 2164fb1cc555SAl Viro if (!path->dentry->d_inode) 2165fb1cc555SAl Viro goto exit_dput; 21669e67f361SAl Viro 21679e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2168fb1cc555SAl Viro return NULL; 2169fb1cc555SAl Viro 2170fb1cc555SAl Viro path_to_nameidata(path, nd); 217131e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2172fb1cc555SAl Viro error = -EISDIR; 217331e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2174fb1cc555SAl Viro goto exit; 217567ee3ad2SAl Viro ok: 21769a66179eSAl Viro filp = finish_open(nd, open_flag, acc_mode); 2177fb1cc555SAl Viro return filp; 2178fb1cc555SAl Viro 2179fb1cc555SAl Viro exit_mutex_unlock: 2180fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2181fb1cc555SAl Viro exit_dput: 2182fb1cc555SAl Viro path_put_conditional(path, nd); 2183fb1cc555SAl Viro exit: 2184fb1cc555SAl Viro if (!IS_ERR(nd->intent.open.file)) 2185fb1cc555SAl Viro release_open_intent(nd); 2186fb1cc555SAl Viro path_put(&nd->path); 2187fb1cc555SAl Viro return ERR_PTR(error); 2188fb1cc555SAl Viro } 2189fb1cc555SAl Viro 21904a3fd211SDave Hansen /* 21914a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 21924a3fd211SDave Hansen * are not the same as in the local variable "flag". See 21934a3fd211SDave Hansen * open_to_namei_flags() for more details. 21941da177e4SLinus Torvalds */ 2195a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 21966e8341a1SAl Viro int open_flag, int mode, int acc_mode) 21971da177e4SLinus Torvalds { 21984a3fd211SDave Hansen struct file *filp; 2199a70e65dfSChristoph Hellwig struct nameidata nd; 22006e8341a1SAl Viro int error; 22019850c056SAl Viro struct path path; 22021da177e4SLinus Torvalds int count = 0; 2203d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 220431e6b01fSNick Piggin int flags; 22051f36f774SAl Viro 22061f36f774SAl Viro if (!(open_flag & O_CREAT)) 22071f36f774SAl Viro mode = 0; 22081da177e4SLinus Torvalds 2209b1085ba8SLino Sanfilippo /* Must never be set by userspace */ 2210b1085ba8SLino Sanfilippo open_flag &= ~FMODE_NONOTIFY; 2211b1085ba8SLino Sanfilippo 22126b2f3d1fSChristoph Hellwig /* 22136b2f3d1fSChristoph Hellwig * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only 22146b2f3d1fSChristoph Hellwig * check for O_DSYNC if the need any syncing at all we enforce it's 22156b2f3d1fSChristoph Hellwig * always set instead of having to deal with possibly weird behaviour 22166b2f3d1fSChristoph Hellwig * for malicious applications setting only __O_SYNC. 22176b2f3d1fSChristoph Hellwig */ 22186b2f3d1fSChristoph Hellwig if (open_flag & __O_SYNC) 22196b2f3d1fSChristoph Hellwig open_flag |= O_DSYNC; 22206b2f3d1fSChristoph Hellwig 22216e8341a1SAl Viro if (!acc_mode) 22226d125529SAl Viro acc_mode = MAY_OPEN | ACC_MODE(open_flag); 22231da177e4SLinus Torvalds 2224834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 22254296e2cbSAl Viro if (open_flag & O_TRUNC) 2226834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 2227834f2a4aSTrond Myklebust 22281da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 22291da177e4SLinus Torvalds access from general write access. */ 22304296e2cbSAl Viro if (open_flag & O_APPEND) 22311da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 22321da177e4SLinus Torvalds 223331e6b01fSNick Piggin flags = LOOKUP_OPEN; 223431e6b01fSNick Piggin if (open_flag & O_CREAT) { 223531e6b01fSNick Piggin flags |= LOOKUP_CREATE; 223631e6b01fSNick Piggin if (open_flag & O_EXCL) 223731e6b01fSNick Piggin flags |= LOOKUP_EXCL; 2238654f562cSJ. R. Okajima } 223931e6b01fSNick Piggin if (open_flag & O_DIRECTORY) 224031e6b01fSNick Piggin flags |= LOOKUP_DIRECTORY; 224131e6b01fSNick Piggin if (!(open_flag & O_NOFOLLOW)) 224231e6b01fSNick Piggin flags |= LOOKUP_FOLLOW; 224331e6b01fSNick Piggin 224431e6b01fSNick Piggin filp = get_empty_filp(); 224531e6b01fSNick Piggin if (!filp) 224631e6b01fSNick Piggin return ERR_PTR(-ENFILE); 224731e6b01fSNick Piggin 224831e6b01fSNick Piggin filp->f_flags = open_flag; 224931e6b01fSNick Piggin nd.intent.open.file = filp; 225031e6b01fSNick Piggin nd.intent.open.flags = flag; 225131e6b01fSNick Piggin nd.intent.open.create_mode = mode; 225231e6b01fSNick Piggin 225331e6b01fSNick Piggin if (open_flag & O_CREAT) 225431e6b01fSNick Piggin goto creat; 225531e6b01fSNick Piggin 225631e6b01fSNick Piggin /* !O_CREAT, simple open */ 225731e6b01fSNick Piggin error = do_path_lookup(dfd, pathname, flags, &nd); 225831e6b01fSNick Piggin if (unlikely(error)) 225931e6b01fSNick Piggin goto out_filp; 226031e6b01fSNick Piggin error = -ELOOP; 226131e6b01fSNick Piggin if (!(nd.flags & LOOKUP_FOLLOW)) { 226231e6b01fSNick Piggin if (nd.inode->i_op->follow_link) 226331e6b01fSNick Piggin goto out_path; 226431e6b01fSNick Piggin } 226531e6b01fSNick Piggin error = -ENOTDIR; 226631e6b01fSNick Piggin if (nd.flags & LOOKUP_DIRECTORY) { 226731e6b01fSNick Piggin if (!nd.inode->i_op->lookup) 226831e6b01fSNick Piggin goto out_path; 226931e6b01fSNick Piggin } 227031e6b01fSNick Piggin audit_inode(pathname, nd.path.dentry); 227131e6b01fSNick Piggin filp = finish_open(&nd, open_flag, acc_mode); 227231e6b01fSNick Piggin return filp; 227331e6b01fSNick Piggin 227431e6b01fSNick Piggin creat: 227531e6b01fSNick Piggin /* OK, have to create the file. Find the parent. */ 227631e6b01fSNick Piggin error = path_init_rcu(dfd, pathname, 227731e6b01fSNick Piggin LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd); 227831e6b01fSNick Piggin if (error) 227931e6b01fSNick Piggin goto out_filp; 228031e6b01fSNick Piggin error = path_walk_rcu(pathname, &nd); 228131e6b01fSNick Piggin path_finish_rcu(&nd); 228231e6b01fSNick Piggin if (unlikely(error == -ECHILD || error == -ESTALE)) { 228331e6b01fSNick Piggin /* slower, locked walk */ 228431e6b01fSNick Piggin if (error == -ESTALE) { 228531e6b01fSNick Piggin reval: 228631e6b01fSNick Piggin flags |= LOOKUP_REVAL; 228731e6b01fSNick Piggin } 228831e6b01fSNick Piggin error = path_init(dfd, pathname, 228931e6b01fSNick Piggin LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd); 229031e6b01fSNick Piggin if (error) 229131e6b01fSNick Piggin goto out_filp; 229231e6b01fSNick Piggin 229331e6b01fSNick Piggin error = path_walk_simple(pathname, &nd); 229431e6b01fSNick Piggin } 229531e6b01fSNick Piggin if (unlikely(error)) 229631e6b01fSNick Piggin goto out_filp; 229731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) 22989b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 22991da177e4SLinus Torvalds 23001da177e4SLinus Torvalds /* 2301a2c36b45SAl Viro * We have the parent and last component. 23021da177e4SLinus Torvalds */ 230331e6b01fSNick Piggin nd.flags = flags; 23043e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 2305806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 2306def4af30SAl Viro struct path holder; 2307def4af30SAl Viro void *cookie; 2308806b681cSAl Viro error = -ELOOP; 23091f36f774SAl Viro /* S_ISDIR part is a temporary automount kludge */ 231031e6b01fSNick Piggin if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(nd.inode->i_mode)) 23111f36f774SAl Viro goto exit_dput; 23121f36f774SAl Viro if (count++ == 32) 2313806b681cSAl Viro goto exit_dput; 2314806b681cSAl Viro /* 2315806b681cSAl Viro * This is subtle. Instead of calling do_follow_link() we do 2316806b681cSAl Viro * the thing by hands. The reason is that this way we have zero 2317806b681cSAl Viro * link_count and path_walk() (called from ->follow_link) 2318806b681cSAl Viro * honoring LOOKUP_PARENT. After that we have the parent and 2319806b681cSAl Viro * last component, i.e. we are in the same situation as after 2320806b681cSAl Viro * the first path_walk(). Well, almost - if the last component 2321806b681cSAl Viro * is normal we get its copy stored in nd->last.name and we will 2322806b681cSAl Viro * have to putname() it when we are done. Procfs-like symlinks 2323806b681cSAl Viro * just set LAST_BIND. 2324806b681cSAl Viro */ 2325806b681cSAl Viro nd.flags |= LOOKUP_PARENT; 2326806b681cSAl Viro error = security_inode_follow_link(path.dentry, &nd); 2327806b681cSAl Viro if (error) 2328806b681cSAl Viro goto exit_dput; 2329def4af30SAl Viro error = __do_follow_link(&path, &nd, &cookie); 2330def4af30SAl Viro if (unlikely(error)) { 233131e6b01fSNick Piggin if (!IS_ERR(cookie) && nd.inode->i_op->put_link) 233231e6b01fSNick Piggin nd.inode->i_op->put_link(path.dentry, &nd, cookie); 2333806b681cSAl Viro /* nd.path had been dropped */ 233431e6b01fSNick Piggin nd.path = path; 233531e6b01fSNick Piggin goto out_path; 2336806b681cSAl Viro } 2337def4af30SAl Viro holder = path; 2338806b681cSAl Viro nd.flags &= ~LOOKUP_PARENT; 23393e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 234031e6b01fSNick Piggin if (nd.inode->i_op->put_link) 234131e6b01fSNick Piggin nd.inode->i_op->put_link(holder.dentry, &nd, cookie); 2342def4af30SAl Viro path_put(&holder); 2343806b681cSAl Viro } 234410fa8e62SAl Viro out: 23452a737871SAl Viro if (nd.root.mnt) 23462a737871SAl Viro path_put(&nd.root); 234731e6b01fSNick Piggin if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL)) 234810fa8e62SAl Viro goto reval; 234910fa8e62SAl Viro return filp; 23501da177e4SLinus Torvalds 2351806b681cSAl Viro exit_dput: 2352806b681cSAl Viro path_put_conditional(&path, &nd); 235331e6b01fSNick Piggin out_path: 235431e6b01fSNick Piggin path_put(&nd.path); 235531e6b01fSNick Piggin out_filp: 2356806b681cSAl Viro if (!IS_ERR(nd.intent.open.file)) 2357a70e65dfSChristoph Hellwig release_open_intent(&nd); 235810fa8e62SAl Viro filp = ERR_PTR(error); 235910fa8e62SAl Viro goto out; 2360de459215SKirill Korotaev } 23611da177e4SLinus Torvalds 23621da177e4SLinus Torvalds /** 2363a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 2364a70e65dfSChristoph Hellwig * 2365a70e65dfSChristoph Hellwig * @filename: path to open 2366a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 2367a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 2368a70e65dfSChristoph Hellwig * 2369a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 2370a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 2371a70e65dfSChristoph Hellwig * along, nothing to see here.. 2372a70e65dfSChristoph Hellwig */ 2373a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 2374a70e65dfSChristoph Hellwig { 23756e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 2376a70e65dfSChristoph Hellwig } 2377a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 2378a70e65dfSChristoph Hellwig 2379a70e65dfSChristoph Hellwig /** 23801da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23811da177e4SLinus Torvalds * @nd: nameidata info 23821da177e4SLinus Torvalds * @is_dir: directory flag 23831da177e4SLinus Torvalds * 23841da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23851da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2386c663e5d8SChristoph Hellwig * 23874ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23881da177e4SLinus Torvalds */ 23891da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23901da177e4SLinus Torvalds { 2391c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23921da177e4SLinus Torvalds 23934ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2394c663e5d8SChristoph Hellwig /* 2395c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2396c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2397c663e5d8SChristoph Hellwig */ 23981da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23991da177e4SLinus Torvalds goto fail; 24001da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 24013516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2402a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2403c663e5d8SChristoph Hellwig 2404c663e5d8SChristoph Hellwig /* 2405c663e5d8SChristoph Hellwig * Do the final lookup. 2406c663e5d8SChristoph Hellwig */ 240749705b77SChristoph Hellwig dentry = lookup_hash(nd); 24081da177e4SLinus Torvalds if (IS_ERR(dentry)) 24091da177e4SLinus Torvalds goto fail; 2410c663e5d8SChristoph Hellwig 2411e9baf6e5SAl Viro if (dentry->d_inode) 2412e9baf6e5SAl Viro goto eexist; 2413c663e5d8SChristoph Hellwig /* 2414c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2415c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2416c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2417c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2418c663e5d8SChristoph Hellwig */ 2419e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 24201da177e4SLinus Torvalds dput(dentry); 24211da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2422e9baf6e5SAl Viro } 2423e9baf6e5SAl Viro return dentry; 2424e9baf6e5SAl Viro eexist: 2425e9baf6e5SAl Viro dput(dentry); 2426e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 24271da177e4SLinus Torvalds fail: 24281da177e4SLinus Torvalds return dentry; 24291da177e4SLinus Torvalds } 2430f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 24311da177e4SLinus Torvalds 24321da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24331da177e4SLinus Torvalds { 2434a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24351da177e4SLinus Torvalds 24361da177e4SLinus Torvalds if (error) 24371da177e4SLinus Torvalds return error; 24381da177e4SLinus Torvalds 24391da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 24401da177e4SLinus Torvalds return -EPERM; 24411da177e4SLinus Torvalds 2442acfa4380SAl Viro if (!dir->i_op->mknod) 24431da177e4SLinus Torvalds return -EPERM; 24441da177e4SLinus Torvalds 244508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 244608ce5f16SSerge E. Hallyn if (error) 244708ce5f16SSerge E. Hallyn return error; 244808ce5f16SSerge E. Hallyn 24491da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24501da177e4SLinus Torvalds if (error) 24511da177e4SLinus Torvalds return error; 24521da177e4SLinus Torvalds 24531da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2454a74574aaSStephen Smalley if (!error) 2455f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24561da177e4SLinus Torvalds return error; 24571da177e4SLinus Torvalds } 24581da177e4SLinus Torvalds 2459463c3197SDave Hansen static int may_mknod(mode_t mode) 2460463c3197SDave Hansen { 2461463c3197SDave Hansen switch (mode & S_IFMT) { 2462463c3197SDave Hansen case S_IFREG: 2463463c3197SDave Hansen case S_IFCHR: 2464463c3197SDave Hansen case S_IFBLK: 2465463c3197SDave Hansen case S_IFIFO: 2466463c3197SDave Hansen case S_IFSOCK: 2467463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2468463c3197SDave Hansen return 0; 2469463c3197SDave Hansen case S_IFDIR: 2470463c3197SDave Hansen return -EPERM; 2471463c3197SDave Hansen default: 2472463c3197SDave Hansen return -EINVAL; 2473463c3197SDave Hansen } 2474463c3197SDave Hansen } 2475463c3197SDave Hansen 24762e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24772e4d0924SHeiko Carstens unsigned, dev) 24781da177e4SLinus Torvalds { 24792ad94ae6SAl Viro int error; 24801da177e4SLinus Torvalds char *tmp; 24811da177e4SLinus Torvalds struct dentry *dentry; 24821da177e4SLinus Torvalds struct nameidata nd; 24831da177e4SLinus Torvalds 24841da177e4SLinus Torvalds if (S_ISDIR(mode)) 24851da177e4SLinus Torvalds return -EPERM; 24861da177e4SLinus Torvalds 24872ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24881da177e4SLinus Torvalds if (error) 24892ad94ae6SAl Viro return error; 24902ad94ae6SAl Viro 24911da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2492463c3197SDave Hansen if (IS_ERR(dentry)) { 24931da177e4SLinus Torvalds error = PTR_ERR(dentry); 2494463c3197SDave Hansen goto out_unlock; 2495463c3197SDave Hansen } 24964ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2497ce3b0f8dSAl Viro mode &= ~current_umask(); 2498463c3197SDave Hansen error = may_mknod(mode); 2499463c3197SDave Hansen if (error) 2500463c3197SDave Hansen goto out_dput; 2501463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2502463c3197SDave Hansen if (error) 2503463c3197SDave Hansen goto out_dput; 2504be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2505be6d3e56SKentaro Takeda if (error) 2506be6d3e56SKentaro Takeda goto out_drop_write; 25071da177e4SLinus Torvalds switch (mode & S_IFMT) { 25081da177e4SLinus Torvalds case 0: case S_IFREG: 25094ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 25101da177e4SLinus Torvalds break; 25111da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 25124ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 25131da177e4SLinus Torvalds new_decode_dev(dev)); 25141da177e4SLinus Torvalds break; 25151da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 25164ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 25171da177e4SLinus Torvalds break; 25181da177e4SLinus Torvalds } 2519be6d3e56SKentaro Takeda out_drop_write: 2520463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2521463c3197SDave Hansen out_dput: 25221da177e4SLinus Torvalds dput(dentry); 2523463c3197SDave Hansen out_unlock: 25244ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25251d957f9bSJan Blunck path_put(&nd.path); 25261da177e4SLinus Torvalds putname(tmp); 25271da177e4SLinus Torvalds 25281da177e4SLinus Torvalds return error; 25291da177e4SLinus Torvalds } 25301da177e4SLinus Torvalds 25313480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25325590ff0dSUlrich Drepper { 25335590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25345590ff0dSUlrich Drepper } 25355590ff0dSUlrich Drepper 25361da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25371da177e4SLinus Torvalds { 2538a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25391da177e4SLinus Torvalds 25401da177e4SLinus Torvalds if (error) 25411da177e4SLinus Torvalds return error; 25421da177e4SLinus Torvalds 2543acfa4380SAl Viro if (!dir->i_op->mkdir) 25441da177e4SLinus Torvalds return -EPERM; 25451da177e4SLinus Torvalds 25461da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25471da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25481da177e4SLinus Torvalds if (error) 25491da177e4SLinus Torvalds return error; 25501da177e4SLinus Torvalds 25511da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2552a74574aaSStephen Smalley if (!error) 2553f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25541da177e4SLinus Torvalds return error; 25551da177e4SLinus Torvalds } 25561da177e4SLinus Torvalds 25572e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25581da177e4SLinus Torvalds { 25591da177e4SLinus Torvalds int error = 0; 25601da177e4SLinus Torvalds char * tmp; 25616902d925SDave Hansen struct dentry *dentry; 25626902d925SDave Hansen struct nameidata nd; 25631da177e4SLinus Torvalds 25642ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25652ad94ae6SAl Viro if (error) 25666902d925SDave Hansen goto out_err; 25671da177e4SLinus Torvalds 25681da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25691da177e4SLinus Torvalds error = PTR_ERR(dentry); 25706902d925SDave Hansen if (IS_ERR(dentry)) 25716902d925SDave Hansen goto out_unlock; 25726902d925SDave Hansen 25734ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2574ce3b0f8dSAl Viro mode &= ~current_umask(); 2575463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2576463c3197SDave Hansen if (error) 2577463c3197SDave Hansen goto out_dput; 2578be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2579be6d3e56SKentaro Takeda if (error) 2580be6d3e56SKentaro Takeda goto out_drop_write; 25814ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2582be6d3e56SKentaro Takeda out_drop_write: 2583463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2584463c3197SDave Hansen out_dput: 25851da177e4SLinus Torvalds dput(dentry); 25866902d925SDave Hansen out_unlock: 25874ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25881d957f9bSJan Blunck path_put(&nd.path); 25891da177e4SLinus Torvalds putname(tmp); 25906902d925SDave Hansen out_err: 25911da177e4SLinus Torvalds return error; 25921da177e4SLinus Torvalds } 25931da177e4SLinus Torvalds 25943cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25955590ff0dSUlrich Drepper { 25965590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25975590ff0dSUlrich Drepper } 25985590ff0dSUlrich Drepper 25991da177e4SLinus Torvalds /* 26001da177e4SLinus Torvalds * We try to drop the dentry early: we should have 26011da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 26021da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 26031da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 26041da177e4SLinus Torvalds * 26051da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 26061da177e4SLinus Torvalds * do a 26071da177e4SLinus Torvalds * 26081da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 26091da177e4SLinus Torvalds * return -EBUSY; 26101da177e4SLinus Torvalds * 26111da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 26121da177e4SLinus Torvalds * that is still in use by something else.. 26131da177e4SLinus Torvalds */ 26141da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 26151da177e4SLinus Torvalds { 26161da177e4SLinus Torvalds dget(dentry); 26171da177e4SLinus Torvalds shrink_dcache_parent(dentry); 26181da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2619b7ab39f6SNick Piggin if (dentry->d_count == 2) 26201da177e4SLinus Torvalds __d_drop(dentry); 26211da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 26221da177e4SLinus Torvalds } 26231da177e4SLinus Torvalds 26241da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 26251da177e4SLinus Torvalds { 26261da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26271da177e4SLinus Torvalds 26281da177e4SLinus Torvalds if (error) 26291da177e4SLinus Torvalds return error; 26301da177e4SLinus Torvalds 2631acfa4380SAl Viro if (!dir->i_op->rmdir) 26321da177e4SLinus Torvalds return -EPERM; 26331da177e4SLinus Torvalds 26341b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26351da177e4SLinus Torvalds dentry_unhash(dentry); 26361da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26371da177e4SLinus Torvalds error = -EBUSY; 26381da177e4SLinus Torvalds else { 26391da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 26401da177e4SLinus Torvalds if (!error) { 26411da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2642d83c49f3SAl Viro if (!error) { 26431da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2644d83c49f3SAl Viro dont_mount(dentry); 2645d83c49f3SAl Viro } 26461da177e4SLinus Torvalds } 26471da177e4SLinus Torvalds } 26481b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26491da177e4SLinus Torvalds if (!error) { 26501da177e4SLinus Torvalds d_delete(dentry); 26511da177e4SLinus Torvalds } 26521da177e4SLinus Torvalds dput(dentry); 26531da177e4SLinus Torvalds 26541da177e4SLinus Torvalds return error; 26551da177e4SLinus Torvalds } 26561da177e4SLinus Torvalds 26575590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26581da177e4SLinus Torvalds { 26591da177e4SLinus Torvalds int error = 0; 26601da177e4SLinus Torvalds char * name; 26611da177e4SLinus Torvalds struct dentry *dentry; 26621da177e4SLinus Torvalds struct nameidata nd; 26631da177e4SLinus Torvalds 26642ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26651da177e4SLinus Torvalds if (error) 26662ad94ae6SAl Viro return error; 26671da177e4SLinus Torvalds 26681da177e4SLinus Torvalds switch(nd.last_type) { 26691da177e4SLinus Torvalds case LAST_DOTDOT: 26701da177e4SLinus Torvalds error = -ENOTEMPTY; 26711da177e4SLinus Torvalds goto exit1; 26721da177e4SLinus Torvalds case LAST_DOT: 26731da177e4SLinus Torvalds error = -EINVAL; 26741da177e4SLinus Torvalds goto exit1; 26751da177e4SLinus Torvalds case LAST_ROOT: 26761da177e4SLinus Torvalds error = -EBUSY; 26771da177e4SLinus Torvalds goto exit1; 26781da177e4SLinus Torvalds } 26790612d9fbSOGAWA Hirofumi 26800612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26810612d9fbSOGAWA Hirofumi 26824ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 268349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26841da177e4SLinus Torvalds error = PTR_ERR(dentry); 26856902d925SDave Hansen if (IS_ERR(dentry)) 26866902d925SDave Hansen goto exit2; 26870622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26880622753bSDave Hansen if (error) 26890622753bSDave Hansen goto exit3; 2690be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2691be6d3e56SKentaro Takeda if (error) 2692be6d3e56SKentaro Takeda goto exit4; 26934ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2694be6d3e56SKentaro Takeda exit4: 26950622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26960622753bSDave Hansen exit3: 26971da177e4SLinus Torvalds dput(dentry); 26986902d925SDave Hansen exit2: 26994ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27001da177e4SLinus Torvalds exit1: 27011d957f9bSJan Blunck path_put(&nd.path); 27021da177e4SLinus Torvalds putname(name); 27031da177e4SLinus Torvalds return error; 27041da177e4SLinus Torvalds } 27051da177e4SLinus Torvalds 27063cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 27075590ff0dSUlrich Drepper { 27085590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 27095590ff0dSUlrich Drepper } 27105590ff0dSUlrich Drepper 27111da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 27121da177e4SLinus Torvalds { 27131da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 27141da177e4SLinus Torvalds 27151da177e4SLinus Torvalds if (error) 27161da177e4SLinus Torvalds return error; 27171da177e4SLinus Torvalds 2718acfa4380SAl Viro if (!dir->i_op->unlink) 27191da177e4SLinus Torvalds return -EPERM; 27201da177e4SLinus Torvalds 27211b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 27221da177e4SLinus Torvalds if (d_mountpoint(dentry)) 27231da177e4SLinus Torvalds error = -EBUSY; 27241da177e4SLinus Torvalds else { 27251da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2726bec1052eSAl Viro if (!error) { 27271da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2728bec1052eSAl Viro if (!error) 2729d83c49f3SAl Viro dont_mount(dentry); 2730bec1052eSAl Viro } 27311da177e4SLinus Torvalds } 27321b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27331da177e4SLinus Torvalds 27341da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27351da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2736ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27371da177e4SLinus Torvalds d_delete(dentry); 27381da177e4SLinus Torvalds } 27390eeca283SRobert Love 27401da177e4SLinus Torvalds return error; 27411da177e4SLinus Torvalds } 27421da177e4SLinus Torvalds 27431da177e4SLinus Torvalds /* 27441da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27451b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27461da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27471da177e4SLinus Torvalds * while waiting on the I/O. 27481da177e4SLinus Torvalds */ 27495590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27501da177e4SLinus Torvalds { 27512ad94ae6SAl Viro int error; 27521da177e4SLinus Torvalds char *name; 27531da177e4SLinus Torvalds struct dentry *dentry; 27541da177e4SLinus Torvalds struct nameidata nd; 27551da177e4SLinus Torvalds struct inode *inode = NULL; 27561da177e4SLinus Torvalds 27572ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27581da177e4SLinus Torvalds if (error) 27592ad94ae6SAl Viro return error; 27602ad94ae6SAl Viro 27611da177e4SLinus Torvalds error = -EISDIR; 27621da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27631da177e4SLinus Torvalds goto exit1; 27640612d9fbSOGAWA Hirofumi 27650612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27660612d9fbSOGAWA Hirofumi 27674ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 276849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27691da177e4SLinus Torvalds error = PTR_ERR(dentry); 27701da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27711da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 27721da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 27731da177e4SLinus Torvalds goto slashes; 27741da177e4SLinus Torvalds inode = dentry->d_inode; 27751da177e4SLinus Torvalds if (inode) 27767de9c6eeSAl Viro ihold(inode); 27770622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27780622753bSDave Hansen if (error) 27790622753bSDave Hansen goto exit2; 2780be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2781be6d3e56SKentaro Takeda if (error) 2782be6d3e56SKentaro Takeda goto exit3; 27834ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2784be6d3e56SKentaro Takeda exit3: 27850622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27861da177e4SLinus Torvalds exit2: 27871da177e4SLinus Torvalds dput(dentry); 27881da177e4SLinus Torvalds } 27894ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27901da177e4SLinus Torvalds if (inode) 27911da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27921da177e4SLinus Torvalds exit1: 27931d957f9bSJan Blunck path_put(&nd.path); 27941da177e4SLinus Torvalds putname(name); 27951da177e4SLinus Torvalds return error; 27961da177e4SLinus Torvalds 27971da177e4SLinus Torvalds slashes: 27981da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27991da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 28001da177e4SLinus Torvalds goto exit2; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 28032e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 28045590ff0dSUlrich Drepper { 28055590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 28065590ff0dSUlrich Drepper return -EINVAL; 28075590ff0dSUlrich Drepper 28085590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 28095590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 28105590ff0dSUlrich Drepper 28115590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 28125590ff0dSUlrich Drepper } 28135590ff0dSUlrich Drepper 28143480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 28155590ff0dSUlrich Drepper { 28165590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 28175590ff0dSUlrich Drepper } 28185590ff0dSUlrich Drepper 2819db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 28201da177e4SLinus Torvalds { 2821a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28221da177e4SLinus Torvalds 28231da177e4SLinus Torvalds if (error) 28241da177e4SLinus Torvalds return error; 28251da177e4SLinus Torvalds 2826acfa4380SAl Viro if (!dir->i_op->symlink) 28271da177e4SLinus Torvalds return -EPERM; 28281da177e4SLinus Torvalds 28291da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28301da177e4SLinus Torvalds if (error) 28311da177e4SLinus Torvalds return error; 28321da177e4SLinus Torvalds 28331da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2834a74574aaSStephen Smalley if (!error) 2835f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28361da177e4SLinus Torvalds return error; 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds 28392e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28402e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28411da177e4SLinus Torvalds { 28422ad94ae6SAl Viro int error; 28431da177e4SLinus Torvalds char *from; 28441da177e4SLinus Torvalds char *to; 28456902d925SDave Hansen struct dentry *dentry; 28466902d925SDave Hansen struct nameidata nd; 28471da177e4SLinus Torvalds 28481da177e4SLinus Torvalds from = getname(oldname); 28491da177e4SLinus Torvalds if (IS_ERR(from)) 28501da177e4SLinus Torvalds return PTR_ERR(from); 28512ad94ae6SAl Viro 28522ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28532ad94ae6SAl Viro if (error) 28546902d925SDave Hansen goto out_putname; 28551da177e4SLinus Torvalds 28561da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28571da177e4SLinus Torvalds error = PTR_ERR(dentry); 28586902d925SDave Hansen if (IS_ERR(dentry)) 28596902d925SDave Hansen goto out_unlock; 28606902d925SDave Hansen 286175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 286275c3f29dSDave Hansen if (error) 286375c3f29dSDave Hansen goto out_dput; 2864be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2865be6d3e56SKentaro Takeda if (error) 2866be6d3e56SKentaro Takeda goto out_drop_write; 2867db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2868be6d3e56SKentaro Takeda out_drop_write: 286975c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 287075c3f29dSDave Hansen out_dput: 28711da177e4SLinus Torvalds dput(dentry); 28726902d925SDave Hansen out_unlock: 28734ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28741d957f9bSJan Blunck path_put(&nd.path); 28751da177e4SLinus Torvalds putname(to); 28766902d925SDave Hansen out_putname: 28771da177e4SLinus Torvalds putname(from); 28781da177e4SLinus Torvalds return error; 28791da177e4SLinus Torvalds } 28801da177e4SLinus Torvalds 28813480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28825590ff0dSUlrich Drepper { 28835590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28845590ff0dSUlrich Drepper } 28855590ff0dSUlrich Drepper 28861da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28871da177e4SLinus Torvalds { 28881da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28891da177e4SLinus Torvalds int error; 28901da177e4SLinus Torvalds 28911da177e4SLinus Torvalds if (!inode) 28921da177e4SLinus Torvalds return -ENOENT; 28931da177e4SLinus Torvalds 2894a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28951da177e4SLinus Torvalds if (error) 28961da177e4SLinus Torvalds return error; 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28991da177e4SLinus Torvalds return -EXDEV; 29001da177e4SLinus Torvalds 29011da177e4SLinus Torvalds /* 29021da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 29031da177e4SLinus Torvalds */ 29041da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 29051da177e4SLinus Torvalds return -EPERM; 2906acfa4380SAl Viro if (!dir->i_op->link) 29071da177e4SLinus Torvalds return -EPERM; 29087e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 29091da177e4SLinus Torvalds return -EPERM; 29101da177e4SLinus Torvalds 29111da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 29121da177e4SLinus Torvalds if (error) 29131da177e4SLinus Torvalds return error; 29141da177e4SLinus Torvalds 29157e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 29161da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 29177e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2918e31e14ecSStephen Smalley if (!error) 29197e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 29201da177e4SLinus Torvalds return error; 29211da177e4SLinus Torvalds } 29221da177e4SLinus Torvalds 29231da177e4SLinus Torvalds /* 29241da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29251da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29261da177e4SLinus Torvalds * newname. --KAB 29271da177e4SLinus Torvalds * 29281da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29291da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29301da177e4SLinus Torvalds * and other special files. --ADM 29311da177e4SLinus Torvalds */ 29322e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29332e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29341da177e4SLinus Torvalds { 29351da177e4SLinus Torvalds struct dentry *new_dentry; 29362d8f3038SAl Viro struct nameidata nd; 29372d8f3038SAl Viro struct path old_path; 29381da177e4SLinus Torvalds int error; 29391da177e4SLinus Torvalds char *to; 29401da177e4SLinus Torvalds 294145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2942c04030e1SUlrich Drepper return -EINVAL; 2943c04030e1SUlrich Drepper 29442d8f3038SAl Viro error = user_path_at(olddfd, oldname, 294545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 29462d8f3038SAl Viro &old_path); 29471da177e4SLinus Torvalds if (error) 29482ad94ae6SAl Viro return error; 29492ad94ae6SAl Viro 29502ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29511da177e4SLinus Torvalds if (error) 29521da177e4SLinus Torvalds goto out; 29531da177e4SLinus Torvalds error = -EXDEV; 29542d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29551da177e4SLinus Torvalds goto out_release; 29561da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29571da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29586902d925SDave Hansen if (IS_ERR(new_dentry)) 29596902d925SDave Hansen goto out_unlock; 296075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 296175c3f29dSDave Hansen if (error) 296275c3f29dSDave Hansen goto out_dput; 2963be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2964be6d3e56SKentaro Takeda if (error) 2965be6d3e56SKentaro Takeda goto out_drop_write; 29662d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2967be6d3e56SKentaro Takeda out_drop_write: 296875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 296975c3f29dSDave Hansen out_dput: 29701da177e4SLinus Torvalds dput(new_dentry); 29716902d925SDave Hansen out_unlock: 29724ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29731da177e4SLinus Torvalds out_release: 29741d957f9bSJan Blunck path_put(&nd.path); 29752ad94ae6SAl Viro putname(to); 29761da177e4SLinus Torvalds out: 29772d8f3038SAl Viro path_put(&old_path); 29781da177e4SLinus Torvalds 29791da177e4SLinus Torvalds return error; 29801da177e4SLinus Torvalds } 29811da177e4SLinus Torvalds 29823480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29835590ff0dSUlrich Drepper { 2984c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29855590ff0dSUlrich Drepper } 29865590ff0dSUlrich Drepper 29871da177e4SLinus Torvalds /* 29881da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29891da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29901da177e4SLinus Torvalds * Problems: 29911da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29921da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29931da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2994a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29951da177e4SLinus Torvalds * story. 29961da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29971b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29981da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29991da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3000a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 30011da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 30021da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 30031da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3004a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 30051da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 30061da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 30071da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 30081da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 30091da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 30101da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 30111da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 30121da177e4SLinus Torvalds * trick as in rmdir(). 30131da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 30141b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 30151da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3016c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 30171da177e4SLinus Torvalds * locking]. 30181da177e4SLinus Torvalds */ 301975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30201da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30211da177e4SLinus Torvalds { 30221da177e4SLinus Torvalds int error = 0; 30231da177e4SLinus Torvalds struct inode *target; 30241da177e4SLinus Torvalds 30251da177e4SLinus Torvalds /* 30261da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30271da177e4SLinus Torvalds * we'll need to flip '..'. 30281da177e4SLinus Torvalds */ 30291da177e4SLinus Torvalds if (new_dir != old_dir) { 3030f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30311da177e4SLinus Torvalds if (error) 30321da177e4SLinus Torvalds return error; 30331da177e4SLinus Torvalds } 30341da177e4SLinus Torvalds 30351da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30361da177e4SLinus Torvalds if (error) 30371da177e4SLinus Torvalds return error; 30381da177e4SLinus Torvalds 30391da177e4SLinus Torvalds target = new_dentry->d_inode; 3040d83c49f3SAl Viro if (target) 30411b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30421da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30431da177e4SLinus Torvalds error = -EBUSY; 3044d83c49f3SAl Viro else { 3045d83c49f3SAl Viro if (target) 3046d83c49f3SAl Viro dentry_unhash(new_dentry); 30471da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3048d83c49f3SAl Viro } 30491da177e4SLinus Torvalds if (target) { 3050d83c49f3SAl Viro if (!error) { 30511da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3052d83c49f3SAl Viro dont_mount(new_dentry); 3053d83c49f3SAl Viro } 30541b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30551da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 30561da177e4SLinus Torvalds d_rehash(new_dentry); 30571da177e4SLinus Torvalds dput(new_dentry); 30581da177e4SLinus Torvalds } 3059e31e14ecSStephen Smalley if (!error) 3060349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30611da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30621da177e4SLinus Torvalds return error; 30631da177e4SLinus Torvalds } 30641da177e4SLinus Torvalds 306575c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30661da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30671da177e4SLinus Torvalds { 30681da177e4SLinus Torvalds struct inode *target; 30691da177e4SLinus Torvalds int error; 30701da177e4SLinus Torvalds 30711da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30721da177e4SLinus Torvalds if (error) 30731da177e4SLinus Torvalds return error; 30741da177e4SLinus Torvalds 30751da177e4SLinus Torvalds dget(new_dentry); 30761da177e4SLinus Torvalds target = new_dentry->d_inode; 30771da177e4SLinus Torvalds if (target) 30781b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30791da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30801da177e4SLinus Torvalds error = -EBUSY; 30811da177e4SLinus Torvalds else 30821da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30831da177e4SLinus Torvalds if (!error) { 3084bec1052eSAl Viro if (target) 3085d83c49f3SAl Viro dont_mount(new_dentry); 3086349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30871da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 30881da177e4SLinus Torvalds } 30891da177e4SLinus Torvalds if (target) 30901b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30911da177e4SLinus Torvalds dput(new_dentry); 30921da177e4SLinus Torvalds return error; 30931da177e4SLinus Torvalds } 30941da177e4SLinus Torvalds 30951da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30961da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30971da177e4SLinus Torvalds { 30981da177e4SLinus Torvalds int error; 30991da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 310059b0df21SEric Paris const unsigned char *old_name; 31011da177e4SLinus Torvalds 31021da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 31031da177e4SLinus Torvalds return 0; 31041da177e4SLinus Torvalds 31051da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 31061da177e4SLinus Torvalds if (error) 31071da177e4SLinus Torvalds return error; 31081da177e4SLinus Torvalds 31091da177e4SLinus Torvalds if (!new_dentry->d_inode) 3110a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 31111da177e4SLinus Torvalds else 31121da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31131da177e4SLinus Torvalds if (error) 31141da177e4SLinus Torvalds return error; 31151da177e4SLinus Torvalds 3116acfa4380SAl Viro if (!old_dir->i_op->rename) 31171da177e4SLinus Torvalds return -EPERM; 31181da177e4SLinus Torvalds 31190eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31200eeca283SRobert Love 31211da177e4SLinus Torvalds if (is_dir) 31221da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31231da177e4SLinus Torvalds else 31241da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3125123df294SAl Viro if (!error) 3126123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31275a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31280eeca283SRobert Love fsnotify_oldname_free(old_name); 31290eeca283SRobert Love 31301da177e4SLinus Torvalds return error; 31311da177e4SLinus Torvalds } 31321da177e4SLinus Torvalds 31332e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31342e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31351da177e4SLinus Torvalds { 31361da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31371da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31381da177e4SLinus Torvalds struct dentry *trap; 31391da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31402ad94ae6SAl Viro char *from; 31412ad94ae6SAl Viro char *to; 31422ad94ae6SAl Viro int error; 31431da177e4SLinus Torvalds 31442ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31451da177e4SLinus Torvalds if (error) 31461da177e4SLinus Torvalds goto exit; 31471da177e4SLinus Torvalds 31482ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31491da177e4SLinus Torvalds if (error) 31501da177e4SLinus Torvalds goto exit1; 31511da177e4SLinus Torvalds 31521da177e4SLinus Torvalds error = -EXDEV; 31534ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31541da177e4SLinus Torvalds goto exit2; 31551da177e4SLinus Torvalds 31564ac91378SJan Blunck old_dir = oldnd.path.dentry; 31571da177e4SLinus Torvalds error = -EBUSY; 31581da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31591da177e4SLinus Torvalds goto exit2; 31601da177e4SLinus Torvalds 31614ac91378SJan Blunck new_dir = newnd.path.dentry; 31621da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31631da177e4SLinus Torvalds goto exit2; 31641da177e4SLinus Torvalds 31650612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31660612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31674e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31680612d9fbSOGAWA Hirofumi 31691da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31701da177e4SLinus Torvalds 317149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31721da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31731da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31741da177e4SLinus Torvalds goto exit3; 31751da177e4SLinus Torvalds /* source must exist */ 31761da177e4SLinus Torvalds error = -ENOENT; 31771da177e4SLinus Torvalds if (!old_dentry->d_inode) 31781da177e4SLinus Torvalds goto exit4; 31791da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31801da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31811da177e4SLinus Torvalds error = -ENOTDIR; 31821da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31831da177e4SLinus Torvalds goto exit4; 31841da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31851da177e4SLinus Torvalds goto exit4; 31861da177e4SLinus Torvalds } 31871da177e4SLinus Torvalds /* source should not be ancestor of target */ 31881da177e4SLinus Torvalds error = -EINVAL; 31891da177e4SLinus Torvalds if (old_dentry == trap) 31901da177e4SLinus Torvalds goto exit4; 319149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31921da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31931da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31941da177e4SLinus Torvalds goto exit4; 31951da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31961da177e4SLinus Torvalds error = -ENOTEMPTY; 31971da177e4SLinus Torvalds if (new_dentry == trap) 31981da177e4SLinus Torvalds goto exit5; 31991da177e4SLinus Torvalds 32009079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 32019079b1ebSDave Hansen if (error) 32029079b1ebSDave Hansen goto exit5; 3203be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3204be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3205be6d3e56SKentaro Takeda if (error) 3206be6d3e56SKentaro Takeda goto exit6; 32071da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 32081da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3209be6d3e56SKentaro Takeda exit6: 32109079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 32111da177e4SLinus Torvalds exit5: 32121da177e4SLinus Torvalds dput(new_dentry); 32131da177e4SLinus Torvalds exit4: 32141da177e4SLinus Torvalds dput(old_dentry); 32151da177e4SLinus Torvalds exit3: 32161da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32171da177e4SLinus Torvalds exit2: 32181d957f9bSJan Blunck path_put(&newnd.path); 32192ad94ae6SAl Viro putname(to); 32201da177e4SLinus Torvalds exit1: 32211d957f9bSJan Blunck path_put(&oldnd.path); 32221da177e4SLinus Torvalds putname(from); 32232ad94ae6SAl Viro exit: 32241da177e4SLinus Torvalds return error; 32251da177e4SLinus Torvalds } 32261da177e4SLinus Torvalds 3227a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32285590ff0dSUlrich Drepper { 32295590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32305590ff0dSUlrich Drepper } 32315590ff0dSUlrich Drepper 32321da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32331da177e4SLinus Torvalds { 32341da177e4SLinus Torvalds int len; 32351da177e4SLinus Torvalds 32361da177e4SLinus Torvalds len = PTR_ERR(link); 32371da177e4SLinus Torvalds if (IS_ERR(link)) 32381da177e4SLinus Torvalds goto out; 32391da177e4SLinus Torvalds 32401da177e4SLinus Torvalds len = strlen(link); 32411da177e4SLinus Torvalds if (len > (unsigned) buflen) 32421da177e4SLinus Torvalds len = buflen; 32431da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32441da177e4SLinus Torvalds len = -EFAULT; 32451da177e4SLinus Torvalds out: 32461da177e4SLinus Torvalds return len; 32471da177e4SLinus Torvalds } 32481da177e4SLinus Torvalds 32491da177e4SLinus Torvalds /* 32501da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32511da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32521da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32531da177e4SLinus Torvalds */ 32541da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32551da177e4SLinus Torvalds { 32561da177e4SLinus Torvalds struct nameidata nd; 3257cc314eefSLinus Torvalds void *cookie; 3258694a1764SMarcin Slusarz int res; 3259cc314eefSLinus Torvalds 32601da177e4SLinus Torvalds nd.depth = 0; 3261cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3262694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3263694a1764SMarcin Slusarz return PTR_ERR(cookie); 3264694a1764SMarcin Slusarz 3265694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32661da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3267cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3268694a1764SMarcin Slusarz return res; 32691da177e4SLinus Torvalds } 32701da177e4SLinus Torvalds 32711da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32721da177e4SLinus Torvalds { 32731da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32741da177e4SLinus Torvalds } 32751da177e4SLinus Torvalds 32761da177e4SLinus Torvalds /* get the link contents into pagecache */ 32771da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32781da177e4SLinus Torvalds { 3279ebd09abbSDuane Griffin char *kaddr; 32801da177e4SLinus Torvalds struct page *page; 32811da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3282090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32831da177e4SLinus Torvalds if (IS_ERR(page)) 32846fe6900eSNick Piggin return (char*)page; 32851da177e4SLinus Torvalds *ppage = page; 3286ebd09abbSDuane Griffin kaddr = kmap(page); 3287ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3288ebd09abbSDuane Griffin return kaddr; 32891da177e4SLinus Torvalds } 32901da177e4SLinus Torvalds 32911da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32921da177e4SLinus Torvalds { 32931da177e4SLinus Torvalds struct page *page = NULL; 32941da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32951da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32961da177e4SLinus Torvalds if (page) { 32971da177e4SLinus Torvalds kunmap(page); 32981da177e4SLinus Torvalds page_cache_release(page); 32991da177e4SLinus Torvalds } 33001da177e4SLinus Torvalds return res; 33011da177e4SLinus Torvalds } 33021da177e4SLinus Torvalds 3303cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 33041da177e4SLinus Torvalds { 3305cc314eefSLinus Torvalds struct page *page = NULL; 33061da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3307cc314eefSLinus Torvalds return page; 33081da177e4SLinus Torvalds } 33091da177e4SLinus Torvalds 3310cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 33111da177e4SLinus Torvalds { 3312cc314eefSLinus Torvalds struct page *page = cookie; 3313cc314eefSLinus Torvalds 3314cc314eefSLinus Torvalds if (page) { 33151da177e4SLinus Torvalds kunmap(page); 33161da177e4SLinus Torvalds page_cache_release(page); 33171da177e4SLinus Torvalds } 33181da177e4SLinus Torvalds } 33191da177e4SLinus Torvalds 332054566b2cSNick Piggin /* 332154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 332254566b2cSNick Piggin */ 332354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33241da177e4SLinus Torvalds { 33251da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33260adb25d2SKirill Korotaev struct page *page; 3327afddba49SNick Piggin void *fsdata; 3328beb497abSDmitriy Monakhov int err; 33291da177e4SLinus Torvalds char *kaddr; 333054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 333154566b2cSNick Piggin if (nofs) 333254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33331da177e4SLinus Torvalds 33347e53cac4SNeilBrown retry: 3335afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 333654566b2cSNick Piggin flags, &page, &fsdata); 33371da177e4SLinus Torvalds if (err) 3338afddba49SNick Piggin goto fail; 3339afddba49SNick Piggin 33401da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33411da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33421da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3343afddba49SNick Piggin 3344afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3345afddba49SNick Piggin page, fsdata); 33461da177e4SLinus Torvalds if (err < 0) 33471da177e4SLinus Torvalds goto fail; 3348afddba49SNick Piggin if (err < len-1) 3349afddba49SNick Piggin goto retry; 3350afddba49SNick Piggin 33511da177e4SLinus Torvalds mark_inode_dirty(inode); 33521da177e4SLinus Torvalds return 0; 33531da177e4SLinus Torvalds fail: 33541da177e4SLinus Torvalds return err; 33551da177e4SLinus Torvalds } 33561da177e4SLinus Torvalds 33570adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33580adb25d2SKirill Korotaev { 33590adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 336054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33610adb25d2SKirill Korotaev } 33620adb25d2SKirill Korotaev 336392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33641da177e4SLinus Torvalds .readlink = generic_readlink, 33651da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33661da177e4SLinus Torvalds .put_link = page_put_link, 33671da177e4SLinus Torvalds }; 33681da177e4SLinus Torvalds 33692d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 33701da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33711da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33721da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33731da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33741da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33751da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33761da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33771da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33781da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33790adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33801da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33811da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 33821da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 3383d1811465SAl Viro EXPORT_SYMBOL(kern_path); 338416f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3385f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33868c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 33871da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33881da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33891da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33901da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33911da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33921da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33931da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33941da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33951da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33961da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33971da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33981da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33991da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 34001da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3401