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 20539191628SRandy Dunlap * @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 38639191628SRandy Dunlap * Returns: 0 on success, -ECHILD 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 44739191628SRandy Dunlap * Returns: 0 on success, -ECHILD 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 { 501a7472babSAl Viro if (nd->flags & LOOKUP_RCU) { 502a7472babSAl Viro if (unlikely(nameidata_dentry_drop_rcu(nd, dentry))) { 503a7472babSAl Viro nd->flags &= ~LOOKUP_RCU; 504a7472babSAl Viro nd->root.mnt = NULL; 505a7472babSAl Viro rcu_read_unlock(); 506a7472babSAl Viro br_read_unlock(vfsmount_lock); 507a7472babSAl Viro return -ECHILD; 508a7472babSAl Viro } 509a7472babSAl Viro } 51031e6b01fSNick Piggin return 0; 51131e6b01fSNick Piggin } 51231e6b01fSNick Piggin 51331e6b01fSNick Piggin /** 51431e6b01fSNick Piggin * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk 51531e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 51639191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 51731e6b01fSNick Piggin * 51831e6b01fSNick Piggin * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. 51931e6b01fSNick Piggin * nd->path should be the final element of the lookup, so nd->root is discarded. 52031e6b01fSNick Piggin * Must be called from rcu-walk context. 52131e6b01fSNick Piggin */ 52231e6b01fSNick Piggin static int nameidata_drop_rcu_last(struct nameidata *nd) 52331e6b01fSNick Piggin { 52431e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 52531e6b01fSNick Piggin 52631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 52731e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 52831e6b01fSNick Piggin nd->root.mnt = NULL; 52931e6b01fSNick Piggin spin_lock(&dentry->d_lock); 53031e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 53131e6b01fSNick Piggin goto err_unlock; 53231e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 53331e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 53431e6b01fSNick Piggin 53531e6b01fSNick Piggin mntget(nd->path.mnt); 53631e6b01fSNick Piggin 53731e6b01fSNick Piggin rcu_read_unlock(); 53831e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 53931e6b01fSNick Piggin 54031e6b01fSNick Piggin return 0; 54131e6b01fSNick Piggin 54231e6b01fSNick Piggin err_unlock: 54331e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 54431e6b01fSNick Piggin rcu_read_unlock(); 54531e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 54631e6b01fSNick Piggin return -ECHILD; 54731e6b01fSNick Piggin } 54831e6b01fSNick Piggin 54931e6b01fSNick Piggin /** 550834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 551834f2a4aSTrond Myklebust * @nd: pointer to nameidata 552834f2a4aSTrond Myklebust */ 553834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 554834f2a4aSTrond Myklebust { 5552dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 5562dab5974SLinus Torvalds 5572dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 5582dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 5592dab5974SLinus Torvalds put_filp(file); 560834f2a4aSTrond Myklebust else 5612dab5974SLinus Torvalds fput(file); 5622dab5974SLinus Torvalds } 563834f2a4aSTrond Myklebust } 564834f2a4aSTrond Myklebust 565f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 56634286d66SNick Piggin { 567f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 56834286d66SNick Piggin } 56934286d66SNick Piggin 570f5e1c1c1SAl Viro static struct dentry * 571bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 572bcdc5e01SIan Kent { 573f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 574bcdc5e01SIan Kent if (unlikely(status <= 0)) { 575bcdc5e01SIan Kent /* 576bcdc5e01SIan Kent * The dentry failed validation. 577bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 578bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 579bcdc5e01SIan Kent * to return a fail status. 580bcdc5e01SIan Kent */ 58134286d66SNick Piggin if (status < 0) { 58234286d66SNick Piggin dput(dentry); 58334286d66SNick Piggin dentry = ERR_PTR(status); 584f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 585bcdc5e01SIan Kent dput(dentry); 586bcdc5e01SIan Kent dentry = NULL; 587bcdc5e01SIan Kent } 588bcdc5e01SIan Kent } 589f5e1c1c1SAl Viro return dentry; 590f5e1c1c1SAl Viro } 591f5e1c1c1SAl Viro 5921da177e4SLinus Torvalds /* 59316c2cd71SAl Viro * handle_reval_path - force revalidation of a dentry 59439159de2SJeff Layton * 59539159de2SJeff Layton * In some situations the path walking code will trust dentries without 59639159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 59739159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 59839159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 59939159de2SJeff Layton * a d_revalidate call before proceeding. 60039159de2SJeff Layton * 60139159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 60239159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 60339159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 60439159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 60539159de2SJeff Layton * to the path if necessary. 60639159de2SJeff Layton */ 60716c2cd71SAl Viro static inline int handle_reval_path(struct nameidata *nd) 60839159de2SJeff Layton { 60916c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 61039159de2SJeff Layton int status; 61139159de2SJeff Layton 61216c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 61339159de2SJeff Layton return 0; 61439159de2SJeff Layton 61516c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 61616c2cd71SAl Viro return 0; 61716c2cd71SAl Viro 61816c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 61916c2cd71SAl Viro return 0; 62016c2cd71SAl Viro 62116c2cd71SAl Viro /* Note: we do not d_invalidate() */ 62234286d66SNick Piggin status = d_revalidate(dentry, nd); 62339159de2SJeff Layton if (status > 0) 62439159de2SJeff Layton return 0; 62539159de2SJeff Layton 62616c2cd71SAl Viro if (!status) 62739159de2SJeff Layton status = -ESTALE; 62816c2cd71SAl Viro 62939159de2SJeff Layton return status; 63039159de2SJeff Layton } 63139159de2SJeff Layton 63239159de2SJeff Layton /* 633b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 634b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 635b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 6361da177e4SLinus Torvalds * 6371da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 638b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 6391da177e4SLinus Torvalds * complete permission check. 6401da177e4SLinus Torvalds */ 641b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 6421da177e4SLinus Torvalds { 6435909ccaaSLinus Torvalds int ret; 6441da177e4SLinus Torvalds 645cb9179eaSLinus Torvalds if (inode->i_op->permission) { 646b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 647b74c79e9SNick Piggin } else { 648b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 649b74c79e9SNick Piggin inode->i_op->check_acl); 650cb9179eaSLinus Torvalds } 651b74c79e9SNick Piggin if (likely(!ret)) 6521da177e4SLinus Torvalds goto ok; 653b74c79e9SNick Piggin if (ret == -ECHILD) 65431e6b01fSNick Piggin return ret; 6551da177e4SLinus Torvalds 656f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 6571da177e4SLinus Torvalds goto ok; 6581da177e4SLinus Torvalds 6595909ccaaSLinus Torvalds return ret; 6601da177e4SLinus Torvalds ok: 661b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 6621da177e4SLinus Torvalds } 6631da177e4SLinus Torvalds 6642a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6652a737871SAl Viro { 666f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 667f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6682a737871SAl Viro } 6692a737871SAl Viro 6706de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6716de88d72SAl Viro 67231e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 67331e6b01fSNick Piggin { 67431e6b01fSNick Piggin if (!nd->root.mnt) { 67531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 676c28cc364SNick Piggin unsigned seq; 677c28cc364SNick Piggin 678c28cc364SNick Piggin do { 679c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 68031e6b01fSNick Piggin nd->root = fs->root; 681c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 68231e6b01fSNick Piggin } 68331e6b01fSNick Piggin } 68431e6b01fSNick Piggin 685f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6861da177e4SLinus Torvalds { 68731e6b01fSNick Piggin int ret; 68831e6b01fSNick Piggin 6891da177e4SLinus Torvalds if (IS_ERR(link)) 6901da177e4SLinus Torvalds goto fail; 6911da177e4SLinus Torvalds 6921da177e4SLinus Torvalds if (*link == '/') { 6932a737871SAl Viro set_root(nd); 6941d957f9bSJan Blunck path_put(&nd->path); 6952a737871SAl Viro nd->path = nd->root; 6962a737871SAl Viro path_get(&nd->root); 69716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6981da177e4SLinus Torvalds } 69931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 700b4091d5fSChristoph Hellwig 70131e6b01fSNick Piggin ret = link_path_walk(link, nd); 70231e6b01fSNick Piggin return ret; 7031da177e4SLinus Torvalds fail: 7041d957f9bSJan Blunck path_put(&nd->path); 7051da177e4SLinus Torvalds return PTR_ERR(link); 7061da177e4SLinus Torvalds } 7071da177e4SLinus Torvalds 7081d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 709051d3812SIan Kent { 710051d3812SIan Kent dput(path->dentry); 7114ac91378SJan Blunck if (path->mnt != nd->path.mnt) 712051d3812SIan Kent mntput(path->mnt); 713051d3812SIan Kent } 714051d3812SIan Kent 7157b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7167b9337aaSNick Piggin struct nameidata *nd) 717051d3812SIan Kent { 71831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7194ac91378SJan Blunck dput(nd->path.dentry); 72031e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7214ac91378SJan Blunck mntput(nd->path.mnt); 7229a229683SHuang Shijie } 72331e6b01fSNick Piggin nd->path.mnt = path->mnt; 7244ac91378SJan Blunck nd->path.dentry = path->dentry; 725051d3812SIan Kent } 726051d3812SIan Kent 727def4af30SAl Viro static __always_inline int 7287b9337aaSNick Piggin __do_follow_link(const struct path *link, struct nameidata *nd, void **p) 7291da177e4SLinus Torvalds { 7301da177e4SLinus Torvalds int error; 7317b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7321da177e4SLinus Torvalds 733844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 734844a3917SAl Viro 7357b9337aaSNick Piggin touch_atime(link->mnt, dentry); 7361da177e4SLinus Torvalds nd_set_link(nd, NULL); 737cd4e91d3SAl Viro 73887556ef1SDavid Howells if (link->mnt == nd->path.mnt) 7397b9337aaSNick Piggin mntget(link->mnt); 74031e6b01fSNick Piggin 74136f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 74236f3b4f6SAl Viro if (error) { 74336f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 74436f3b4f6SAl Viro path_put(&nd->path); 74536f3b4f6SAl Viro return error; 74636f3b4f6SAl Viro } 74736f3b4f6SAl Viro 74886acdca1SAl Viro nd->last_type = LAST_BIND; 749def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 750def4af30SAl Viro error = PTR_ERR(*p); 751def4af30SAl Viro if (!IS_ERR(*p)) { 7521da177e4SLinus Torvalds char *s = nd_get_link(nd); 753cc314eefSLinus Torvalds error = 0; 7541da177e4SLinus Torvalds if (s) 7551da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 75616c2cd71SAl Viro else if (nd->last_type == LAST_BIND) 75716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 7581da177e4SLinus Torvalds } 7591da177e4SLinus Torvalds return error; 7601da177e4SLinus Torvalds } 7611da177e4SLinus Torvalds 7621da177e4SLinus Torvalds /* 7631da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 7641da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 7651da177e4SLinus Torvalds * 7661da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 7671da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 7681da177e4SLinus Torvalds */ 7693abb17e8SLinus Torvalds static inline int do_follow_link(struct inode *inode, struct path *path, struct nameidata *nd) 7701da177e4SLinus Torvalds { 771def4af30SAl Viro void *cookie; 7721da177e4SLinus Torvalds int err = -ELOOP; 773844a3917SAl Viro 774844a3917SAl Viro /* We drop rcu-walk here */ 775844a3917SAl Viro if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry)) 776844a3917SAl Viro return -ECHILD; 7773abb17e8SLinus Torvalds BUG_ON(inode != path->dentry->d_inode); 778844a3917SAl Viro 7791da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 7801da177e4SLinus Torvalds goto loop; 7811da177e4SLinus Torvalds if (current->total_link_count >= 40) 7821da177e4SLinus Torvalds goto loop; 7831da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 7841da177e4SLinus Torvalds cond_resched(); 7851da177e4SLinus Torvalds current->link_count++; 7861da177e4SLinus Torvalds current->total_link_count++; 7871da177e4SLinus Torvalds nd->depth++; 788def4af30SAl Viro err = __do_follow_link(path, nd, &cookie); 789def4af30SAl Viro if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link) 790def4af30SAl Viro path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie); 791258fa999SAl Viro path_put(path); 7921da177e4SLinus Torvalds current->link_count--; 7931da177e4SLinus Torvalds nd->depth--; 7941da177e4SLinus Torvalds return err; 7951da177e4SLinus Torvalds loop: 7961d957f9bSJan Blunck path_put_conditional(path, nd); 7971d957f9bSJan Blunck path_put(&nd->path); 7981da177e4SLinus Torvalds return err; 7991da177e4SLinus Torvalds } 8001da177e4SLinus Torvalds 80131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 80231e6b01fSNick Piggin { 80331e6b01fSNick Piggin struct vfsmount *parent; 80431e6b01fSNick Piggin struct dentry *mountpoint; 80531e6b01fSNick Piggin 80631e6b01fSNick Piggin parent = path->mnt->mnt_parent; 80731e6b01fSNick Piggin if (parent == path->mnt) 80831e6b01fSNick Piggin return 0; 80931e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 81031e6b01fSNick Piggin path->dentry = mountpoint; 81131e6b01fSNick Piggin path->mnt = parent; 81231e6b01fSNick Piggin return 1; 81331e6b01fSNick Piggin } 81431e6b01fSNick Piggin 815bab77ebfSAl Viro int follow_up(struct path *path) 8161da177e4SLinus Torvalds { 8171da177e4SLinus Torvalds struct vfsmount *parent; 8181da177e4SLinus Torvalds struct dentry *mountpoint; 81999b7db7bSNick Piggin 82099b7db7bSNick Piggin br_read_lock(vfsmount_lock); 821bab77ebfSAl Viro parent = path->mnt->mnt_parent; 822bab77ebfSAl Viro if (parent == path->mnt) { 82399b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 8241da177e4SLinus Torvalds return 0; 8251da177e4SLinus Torvalds } 8261da177e4SLinus Torvalds mntget(parent); 827bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 82899b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 829bab77ebfSAl Viro dput(path->dentry); 830bab77ebfSAl Viro path->dentry = mountpoint; 831bab77ebfSAl Viro mntput(path->mnt); 832bab77ebfSAl Viro path->mnt = parent; 8331da177e4SLinus Torvalds return 1; 8341da177e4SLinus Torvalds } 8351da177e4SLinus Torvalds 836b5c84bf6SNick Piggin /* 8379875cf80SDavid Howells * Perform an automount 8389875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 8399875cf80SDavid Howells * were called with. 8401da177e4SLinus Torvalds */ 8419875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 8429875cf80SDavid Howells bool *need_mntput) 84331e6b01fSNick Piggin { 8449875cf80SDavid Howells struct vfsmount *mnt; 845ea5b778aSDavid Howells int err; 8469875cf80SDavid Howells 8479875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 8489875cf80SDavid Howells return -EREMOTE; 8499875cf80SDavid Howells 8506f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 8516f45b656SDavid Howells * and this is the terminal part of the path. 8526f45b656SDavid Howells */ 8536f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 8546f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 8556f45b656SDavid Howells 8569875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 8579875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 8589875cf80SDavid Howells * or wants to open the mounted directory. 8599875cf80SDavid Howells * 8609875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 8619875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 8629875cf80SDavid Howells * appended a '/' to the name. 8639875cf80SDavid Howells */ 8649875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 8659875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 8669875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 8679875cf80SDavid Howells return -EISDIR; 8689875cf80SDavid Howells 8699875cf80SDavid Howells current->total_link_count++; 8709875cf80SDavid Howells if (current->total_link_count >= 40) 8719875cf80SDavid Howells return -ELOOP; 8729875cf80SDavid Howells 8739875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 8749875cf80SDavid Howells if (IS_ERR(mnt)) { 8759875cf80SDavid Howells /* 8769875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 8779875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 8789875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 8799875cf80SDavid Howells * 8809875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 8819875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 8829875cf80SDavid Howells * the path is inaccessible and we should say so. 8839875cf80SDavid Howells */ 8849875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 8859875cf80SDavid Howells return -EREMOTE; 8869875cf80SDavid Howells return PTR_ERR(mnt); 88731e6b01fSNick Piggin } 888ea5b778aSDavid Howells 8899875cf80SDavid Howells if (!mnt) /* mount collision */ 8909875cf80SDavid Howells return 0; 8919875cf80SDavid Howells 89219a167afSAl Viro err = finish_automount(mnt, path); 893ea5b778aSDavid Howells 894ea5b778aSDavid Howells switch (err) { 895ea5b778aSDavid Howells case -EBUSY: 896ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 89719a167afSAl Viro return 0; 898ea5b778aSDavid Howells case 0: 899463ffb2eSAl Viro dput(path->dentry); 9009875cf80SDavid Howells if (*need_mntput) 9019875cf80SDavid Howells mntput(path->mnt); 9029875cf80SDavid Howells path->mnt = mnt; 9039875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9049875cf80SDavid Howells *need_mntput = true; 9059875cf80SDavid Howells return 0; 90619a167afSAl Viro default: 90719a167afSAl Viro return err; 9089875cf80SDavid Howells } 90919a167afSAl Viro 910ea5b778aSDavid Howells } 9119875cf80SDavid Howells 9129875cf80SDavid Howells /* 9139875cf80SDavid Howells * Handle a dentry that is managed in some way. 914cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9159875cf80SDavid Howells * - Flagged as mountpoint 9169875cf80SDavid Howells * - Flagged as automount point 9179875cf80SDavid Howells * 9189875cf80SDavid Howells * This may only be called in refwalk mode. 9199875cf80SDavid Howells * 9209875cf80SDavid Howells * Serialization is taken care of in namespace.c 9219875cf80SDavid Howells */ 9229875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9239875cf80SDavid Howells { 9249875cf80SDavid Howells unsigned managed; 9259875cf80SDavid Howells bool need_mntput = false; 9269875cf80SDavid Howells int ret; 9279875cf80SDavid Howells 9289875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9299875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9309875cf80SDavid Howells * the components of that value change under us */ 9319875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9329875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9339875cf80SDavid Howells unlikely(managed != 0)) { 934cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 935cc53ce53SDavid Howells * being held. */ 936cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 937cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 938cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 939ab90911fSDavid Howells ret = path->dentry->d_op->d_manage(path->dentry, 940ab90911fSDavid Howells false, false); 941cc53ce53SDavid Howells if (ret < 0) 942cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 943cc53ce53SDavid Howells } 944cc53ce53SDavid Howells 9459875cf80SDavid Howells /* Transit to a mounted filesystem. */ 9469875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 9479875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9489875cf80SDavid Howells if (mounted) { 9499875cf80SDavid Howells dput(path->dentry); 9509875cf80SDavid Howells if (need_mntput) 951463ffb2eSAl Viro mntput(path->mnt); 952463ffb2eSAl Viro path->mnt = mounted; 953463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 9549875cf80SDavid Howells need_mntput = true; 9559875cf80SDavid Howells continue; 956463ffb2eSAl Viro } 957463ffb2eSAl Viro 9589875cf80SDavid Howells /* Something is mounted on this dentry in another 9599875cf80SDavid Howells * namespace and/or whatever was mounted there in this 9609875cf80SDavid Howells * namespace got unmounted before we managed to get the 9619875cf80SDavid Howells * vfsmount_lock */ 9621da177e4SLinus Torvalds } 9639875cf80SDavid Howells 9649875cf80SDavid Howells /* Handle an automount point */ 9659875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 9669875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 9679875cf80SDavid Howells if (ret < 0) 9689875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 9699875cf80SDavid Howells continue; 9709875cf80SDavid Howells } 9719875cf80SDavid Howells 9729875cf80SDavid Howells /* We didn't change the current path point */ 9739875cf80SDavid Howells break; 9749875cf80SDavid Howells } 9759875cf80SDavid Howells return 0; 9761da177e4SLinus Torvalds } 9771da177e4SLinus Torvalds 978cc53ce53SDavid Howells int follow_down_one(struct path *path) 9791da177e4SLinus Torvalds { 9801da177e4SLinus Torvalds struct vfsmount *mounted; 9811da177e4SLinus Torvalds 9821c755af4SAl Viro mounted = lookup_mnt(path); 9831da177e4SLinus Torvalds if (mounted) { 9849393bd07SAl Viro dput(path->dentry); 9859393bd07SAl Viro mntput(path->mnt); 9869393bd07SAl Viro path->mnt = mounted; 9879393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 9881da177e4SLinus Torvalds return 1; 9891da177e4SLinus Torvalds } 9901da177e4SLinus Torvalds return 0; 9911da177e4SLinus Torvalds } 9921da177e4SLinus Torvalds 9939875cf80SDavid Howells /* 9949875cf80SDavid Howells * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we 995cc53ce53SDavid Howells * meet a managed dentry and we're not walking to "..". True is returned to 9969875cf80SDavid Howells * continue, false to abort. 9979875cf80SDavid Howells */ 9989875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 9999875cf80SDavid Howells struct inode **inode, bool reverse_transit) 10009875cf80SDavid Howells { 10019875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10029875cf80SDavid Howells struct vfsmount *mounted; 1003ab90911fSDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) && 1004ab90911fSDavid Howells !reverse_transit && 1005ab90911fSDavid Howells path->dentry->d_op->d_manage(path->dentry, false, true) < 0) 1006ab90911fSDavid Howells return false; 10079875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 10089875cf80SDavid Howells if (!mounted) 10099875cf80SDavid Howells break; 10109875cf80SDavid Howells path->mnt = mounted; 10119875cf80SDavid Howells path->dentry = mounted->mnt_root; 10129875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 10139875cf80SDavid Howells *inode = path->dentry->d_inode; 10149875cf80SDavid Howells } 10159875cf80SDavid Howells 10169875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 10179875cf80SDavid Howells return reverse_transit; 10189875cf80SDavid Howells return true; 10199875cf80SDavid Howells } 10209875cf80SDavid Howells 102131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 102231e6b01fSNick Piggin { 102331e6b01fSNick Piggin struct inode *inode = nd->inode; 102431e6b01fSNick Piggin 102531e6b01fSNick Piggin set_root_rcu(nd); 102631e6b01fSNick Piggin 102731e6b01fSNick Piggin while (1) { 102831e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 102931e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 103031e6b01fSNick Piggin break; 103131e6b01fSNick Piggin } 103231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 103331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 103431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 103531e6b01fSNick Piggin unsigned seq; 103631e6b01fSNick Piggin 103731e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 103831e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1039ef7562d5SAl Viro goto failed; 104031e6b01fSNick Piggin inode = parent->d_inode; 104131e6b01fSNick Piggin nd->path.dentry = parent; 104231e6b01fSNick Piggin nd->seq = seq; 104331e6b01fSNick Piggin break; 104431e6b01fSNick Piggin } 104531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 104631e6b01fSNick Piggin break; 104731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 104831e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 104931e6b01fSNick Piggin } 10509875cf80SDavid Howells __follow_mount_rcu(nd, &nd->path, &inode, true); 105131e6b01fSNick Piggin nd->inode = inode; 105231e6b01fSNick Piggin return 0; 1053ef7562d5SAl Viro 1054ef7562d5SAl Viro failed: 1055ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 1056ef7562d5SAl Viro nd->root.mnt = NULL; 1057ef7562d5SAl Viro rcu_read_unlock(); 1058ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 1059ef7562d5SAl Viro return -ECHILD; 106031e6b01fSNick Piggin } 106131e6b01fSNick Piggin 10629875cf80SDavid Howells /* 1063cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1064cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1065cc53ce53SDavid Howells * caller is permitted to proceed or not. 1066cc53ce53SDavid Howells * 1067cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1068cc53ce53SDavid Howells * being true). 1069cc53ce53SDavid Howells */ 1070cc53ce53SDavid Howells int follow_down(struct path *path, bool mounting_here) 1071cc53ce53SDavid Howells { 1072cc53ce53SDavid Howells unsigned managed; 1073cc53ce53SDavid Howells int ret; 1074cc53ce53SDavid Howells 1075cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1076cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1077cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1078cc53ce53SDavid Howells * being held. 1079cc53ce53SDavid Howells * 1080cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1081cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1082cc53ce53SDavid Howells * other than its daemon the right to mount on its 1083cc53ce53SDavid Howells * superstructure. 1084cc53ce53SDavid Howells * 1085cc53ce53SDavid Howells * The filesystem may sleep at this point. 1086cc53ce53SDavid Howells */ 1087cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1088cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1089cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1090ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 1091ab90911fSDavid Howells path->dentry, mounting_here, false); 1092cc53ce53SDavid Howells if (ret < 0) 1093cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1094cc53ce53SDavid Howells } 1095cc53ce53SDavid Howells 1096cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1097cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1098cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1099cc53ce53SDavid Howells if (!mounted) 1100cc53ce53SDavid Howells break; 1101cc53ce53SDavid Howells dput(path->dentry); 1102cc53ce53SDavid Howells mntput(path->mnt); 1103cc53ce53SDavid Howells path->mnt = mounted; 1104cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1105cc53ce53SDavid Howells continue; 1106cc53ce53SDavid Howells } 1107cc53ce53SDavid Howells 1108cc53ce53SDavid Howells /* Don't handle automount points here */ 1109cc53ce53SDavid Howells break; 1110cc53ce53SDavid Howells } 1111cc53ce53SDavid Howells return 0; 1112cc53ce53SDavid Howells } 1113cc53ce53SDavid Howells 1114cc53ce53SDavid Howells /* 11159875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 11169875cf80SDavid Howells */ 11179875cf80SDavid Howells static void follow_mount(struct path *path) 11189875cf80SDavid Howells { 11199875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11209875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11219875cf80SDavid Howells if (!mounted) 11229875cf80SDavid Howells break; 11239875cf80SDavid Howells dput(path->dentry); 11249875cf80SDavid Howells mntput(path->mnt); 11259875cf80SDavid Howells path->mnt = mounted; 11269875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11279875cf80SDavid Howells } 11289875cf80SDavid Howells } 11299875cf80SDavid Howells 113031e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11311da177e4SLinus Torvalds { 11322a737871SAl Viro set_root(nd); 1133e518ddb7SAndreas Mohr 11341da177e4SLinus Torvalds while(1) { 11354ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11361da177e4SLinus Torvalds 11372a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11382a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11391da177e4SLinus Torvalds break; 11401da177e4SLinus Torvalds } 11414ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11423088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11433088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11441da177e4SLinus Torvalds dput(old); 11451da177e4SLinus Torvalds break; 11461da177e4SLinus Torvalds } 11473088dd70SAl Viro if (!follow_up(&nd->path)) 11481da177e4SLinus Torvalds break; 11491da177e4SLinus Torvalds } 115079ed0226SAl Viro follow_mount(&nd->path); 115131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11521da177e4SLinus Torvalds } 11531da177e4SLinus Torvalds 11541da177e4SLinus Torvalds /* 1155baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1156baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1157baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1158baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1159baa03890SNick Piggin */ 1160baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1161baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1162baa03890SNick Piggin { 1163baa03890SNick Piggin struct inode *inode = parent->d_inode; 1164baa03890SNick Piggin struct dentry *dentry; 1165baa03890SNick Piggin struct dentry *old; 1166baa03890SNick Piggin 1167baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1168baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1169baa03890SNick Piggin return ERR_PTR(-ENOENT); 1170baa03890SNick Piggin 1171baa03890SNick Piggin dentry = d_alloc(parent, name); 1172baa03890SNick Piggin if (unlikely(!dentry)) 1173baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1174baa03890SNick Piggin 1175baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1176baa03890SNick Piggin if (unlikely(old)) { 1177baa03890SNick Piggin dput(dentry); 1178baa03890SNick Piggin dentry = old; 1179baa03890SNick Piggin } 1180baa03890SNick Piggin return dentry; 1181baa03890SNick Piggin } 1182baa03890SNick Piggin 1183baa03890SNick Piggin /* 11841da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11851da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11861da177e4SLinus Torvalds * It _is_ time-critical. 11871da177e4SLinus Torvalds */ 11881da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 118931e6b01fSNick Piggin struct path *path, struct inode **inode) 11901da177e4SLinus Torvalds { 11914ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 119231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11935a18fff2SAl Viro int need_reval = 1; 11945a18fff2SAl Viro int status = 1; 11959875cf80SDavid Howells int err; 11969875cf80SDavid Howells 11973cac260aSAl Viro /* 1198b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1199b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1200b04f784eSNick Piggin * do the non-racy lookup, below. 1201b04f784eSNick Piggin */ 120231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 120331e6b01fSNick Piggin unsigned seq; 120431e6b01fSNick Piggin *inode = nd->inode; 120531e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 12065a18fff2SAl Viro if (!dentry) 12075a18fff2SAl Viro goto unlazy; 12085a18fff2SAl Viro 120931e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 121031e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 121131e6b01fSNick Piggin return -ECHILD; 121231e6b01fSNick Piggin nd->seq = seq; 12135a18fff2SAl Viro 121424643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 12155a18fff2SAl Viro status = d_revalidate(dentry, nd); 12165a18fff2SAl Viro if (unlikely(status <= 0)) { 12175a18fff2SAl Viro if (status != -ECHILD) 12185a18fff2SAl Viro need_reval = 0; 12195a18fff2SAl Viro goto unlazy; 12205a18fff2SAl Viro } 122124643087SAl Viro } 122231e6b01fSNick Piggin path->mnt = mnt; 122331e6b01fSNick Piggin path->dentry = dentry; 12249875cf80SDavid Howells if (likely(__follow_mount_rcu(nd, path, inode, false))) 12259875cf80SDavid Howells return 0; 12265a18fff2SAl Viro unlazy: 12275a18fff2SAl Viro if (dentry) { 12285a18fff2SAl Viro if (nameidata_dentry_drop_rcu(nd, dentry)) 12295a18fff2SAl Viro return -ECHILD; 12305a18fff2SAl Viro } else { 12319875cf80SDavid Howells if (nameidata_drop_rcu(nd)) 12329875cf80SDavid Howells return -ECHILD; 12339875cf80SDavid Howells } 12345a18fff2SAl Viro } else { 123531e6b01fSNick Piggin dentry = __d_lookup(parent, name); 123624643087SAl Viro } 12375a18fff2SAl Viro 12385a18fff2SAl Viro retry: 12395a18fff2SAl Viro if (unlikely(!dentry)) { 12405a18fff2SAl Viro struct inode *dir = parent->d_inode; 12415a18fff2SAl Viro BUG_ON(nd->inode != dir); 12425a18fff2SAl Viro 12435a18fff2SAl Viro mutex_lock(&dir->i_mutex); 12445a18fff2SAl Viro dentry = d_lookup(parent, name); 12455a18fff2SAl Viro if (likely(!dentry)) { 12465a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 12475a18fff2SAl Viro if (IS_ERR(dentry)) { 12485a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12495a18fff2SAl Viro return PTR_ERR(dentry); 12505a18fff2SAl Viro } 12515a18fff2SAl Viro /* known good */ 12525a18fff2SAl Viro need_reval = 0; 12535a18fff2SAl Viro status = 1; 12545a18fff2SAl Viro } 12555a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 12565a18fff2SAl Viro } 12575a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 12585a18fff2SAl Viro status = d_revalidate(dentry, nd); 12595a18fff2SAl Viro if (unlikely(status <= 0)) { 12605a18fff2SAl Viro if (status < 0) { 12615a18fff2SAl Viro dput(dentry); 12625a18fff2SAl Viro return status; 12635a18fff2SAl Viro } 12645a18fff2SAl Viro if (!d_invalidate(dentry)) { 12655a18fff2SAl Viro dput(dentry); 12665a18fff2SAl Viro dentry = NULL; 12675a18fff2SAl Viro need_reval = 1; 12685a18fff2SAl Viro goto retry; 12695a18fff2SAl Viro } 12705a18fff2SAl Viro } 12715a18fff2SAl Viro 12721da177e4SLinus Torvalds path->mnt = mnt; 12731da177e4SLinus Torvalds path->dentry = dentry; 12749875cf80SDavid Howells err = follow_managed(path, nd->flags); 127589312214SIan Kent if (unlikely(err < 0)) { 127689312214SIan Kent path_put_conditional(path, nd); 12779875cf80SDavid Howells return err; 127889312214SIan Kent } 127931e6b01fSNick Piggin *inode = path->dentry->d_inode; 12801da177e4SLinus Torvalds return 0; 12811da177e4SLinus Torvalds } 12821da177e4SLinus Torvalds 128352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 128452094c8aSAl Viro { 128552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 128652094c8aSAl Viro int err = exec_permission(nd->inode, IPERM_FLAG_RCU); 128752094c8aSAl Viro if (err != -ECHILD) 128852094c8aSAl Viro return err; 128952094c8aSAl Viro if (nameidata_drop_rcu(nd)) 129052094c8aSAl Viro return -ECHILD; 129152094c8aSAl Viro } 129252094c8aSAl Viro return exec_permission(nd->inode, 0); 129352094c8aSAl Viro } 129452094c8aSAl Viro 12959856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12969856fa1bSAl Viro { 12979856fa1bSAl Viro if (type == LAST_DOTDOT) { 12989856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12999856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 13009856fa1bSAl Viro return -ECHILD; 13019856fa1bSAl Viro } else 13029856fa1bSAl Viro follow_dotdot(nd); 13039856fa1bSAl Viro } 13049856fa1bSAl Viro return 0; 13059856fa1bSAl Viro } 13069856fa1bSAl Viro 1307951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1308951361f9SAl Viro { 1309951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1310951361f9SAl Viro path_put(&nd->path); 1311951361f9SAl Viro } else { 1312951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 1313951361f9SAl Viro nd->root.mnt = NULL; 1314951361f9SAl Viro rcu_read_unlock(); 1315951361f9SAl Viro br_read_unlock(vfsmount_lock); 1316951361f9SAl Viro } 1317951361f9SAl Viro } 1318951361f9SAl Viro 13191da177e4SLinus Torvalds /* 13201da177e4SLinus Torvalds * Name resolution. 1321ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1322ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13231da177e4SLinus Torvalds * 1324ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1325ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13261da177e4SLinus Torvalds */ 13276de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13281da177e4SLinus Torvalds { 13291da177e4SLinus Torvalds struct path next; 13301da177e4SLinus Torvalds int err; 13311da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13321da177e4SLinus Torvalds 13331da177e4SLinus Torvalds while (*name=='/') 13341da177e4SLinus Torvalds name++; 13351da177e4SLinus Torvalds if (!*name) 1336086e183aSAl Viro return 0; 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds if (nd->depth) 1339f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 13401da177e4SLinus Torvalds 13411da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13421da177e4SLinus Torvalds for(;;) { 134331e6b01fSNick Piggin struct inode *inode; 13441da177e4SLinus Torvalds unsigned long hash; 13451da177e4SLinus Torvalds struct qstr this; 13461da177e4SLinus Torvalds unsigned int c; 1347fe479a58SAl Viro int type; 13481da177e4SLinus Torvalds 1349cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 135052094c8aSAl Viro 135152094c8aSAl Viro err = may_lookup(nd); 13521da177e4SLinus Torvalds if (err) 13531da177e4SLinus Torvalds break; 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds this.name = name; 13561da177e4SLinus Torvalds c = *(const unsigned char *)name; 13571da177e4SLinus Torvalds 13581da177e4SLinus Torvalds hash = init_name_hash(); 13591da177e4SLinus Torvalds do { 13601da177e4SLinus Torvalds name++; 13611da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13621da177e4SLinus Torvalds c = *(const unsigned char *)name; 13631da177e4SLinus Torvalds } while (c && (c != '/')); 13641da177e4SLinus Torvalds this.len = name - (const char *) this.name; 13651da177e4SLinus Torvalds this.hash = end_name_hash(hash); 13661da177e4SLinus Torvalds 1367fe479a58SAl Viro type = LAST_NORM; 1368fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1369fe479a58SAl Viro case 2: 137016c2cd71SAl Viro if (this.name[1] == '.') { 1371fe479a58SAl Viro type = LAST_DOTDOT; 137216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 137316c2cd71SAl Viro } 1374fe479a58SAl Viro break; 1375fe479a58SAl Viro case 1: 1376fe479a58SAl Viro type = LAST_DOT; 1377fe479a58SAl Viro } 13785a202bcdSAl Viro if (likely(type == LAST_NORM)) { 13795a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 138016c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 13815a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 13825a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 13835a202bcdSAl Viro &this); 13845a202bcdSAl Viro if (err < 0) 13855a202bcdSAl Viro break; 13865a202bcdSAl Viro } 13875a202bcdSAl Viro } 1388fe479a58SAl Viro 13891da177e4SLinus Torvalds /* remove trailing slashes? */ 13901da177e4SLinus Torvalds if (!c) 13911da177e4SLinus Torvalds goto last_component; 13921da177e4SLinus Torvalds while (*++name == '/'); 13931da177e4SLinus Torvalds if (!*name) 13941da177e4SLinus Torvalds goto last_with_slashes; 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds /* 13971da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 13981da177e4SLinus Torvalds * to be able to know about the current root directory and 13991da177e4SLinus Torvalds * parent relationships. 14001da177e4SLinus Torvalds */ 1401fe479a58SAl Viro if (unlikely(type != LAST_NORM)) { 1402ef7562d5SAl Viro if (handle_dots(nd, type)) 1403ef7562d5SAl Viro return -ECHILD; 14041da177e4SLinus Torvalds continue; 14051da177e4SLinus Torvalds } 1406fe479a58SAl Viro 14071da177e4SLinus Torvalds /* This does the actual lookups.. */ 140831e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 14091da177e4SLinus Torvalds if (err) 14101da177e4SLinus Torvalds break; 14111da177e4SLinus Torvalds 14127bc055d1SAl Viro if (inode && inode->i_op->follow_link) { 14133abb17e8SLinus Torvalds err = do_follow_link(inode, &next, nd); 14141da177e4SLinus Torvalds if (err) 1415a7472babSAl Viro return err; 141631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 141731e6b01fSNick Piggin } else { 141809dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 141931e6b01fSNick Piggin nd->inode = inode; 142031e6b01fSNick Piggin } 14217bc055d1SAl Viro err = -ENOENT; 14227bc055d1SAl Viro if (!nd->inode) 14237bc055d1SAl Viro break; 14241da177e4SLinus Torvalds err = -ENOTDIR; 142531e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14261da177e4SLinus Torvalds break; 14271da177e4SLinus Torvalds continue; 14281da177e4SLinus Torvalds /* here ends the main loop */ 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds last_with_slashes: 14311da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 14321da177e4SLinus Torvalds last_component: 1433f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1434f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 14351da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 14361da177e4SLinus Torvalds goto lookup_parent; 1437ef7562d5SAl Viro if (unlikely(type != LAST_NORM)) 1438ef7562d5SAl Viro return handle_dots(nd, type); 143931e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 14401da177e4SLinus Torvalds if (err) 14411da177e4SLinus Torvalds break; 1442db372915SDavid Howells if (inode && unlikely(inode->i_op->follow_link) && 1443db372915SDavid Howells (lookup_flags & LOOKUP_FOLLOW)) { 14443abb17e8SLinus Torvalds err = do_follow_link(inode, &next, nd); 14451da177e4SLinus Torvalds if (err) 1446a7472babSAl Viro return err; 144731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 144831e6b01fSNick Piggin } else { 144909dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 145031e6b01fSNick Piggin nd->inode = inode; 145131e6b01fSNick Piggin } 14521da177e4SLinus Torvalds err = -ENOENT; 145331e6b01fSNick Piggin if (!nd->inode) 14541da177e4SLinus Torvalds break; 14551da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 14561da177e4SLinus Torvalds err = -ENOTDIR; 145731e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14581da177e4SLinus Torvalds break; 14591da177e4SLinus Torvalds } 1460086e183aSAl Viro return 0; 14611da177e4SLinus Torvalds lookup_parent: 14621da177e4SLinus Torvalds nd->last = this; 1463fe479a58SAl Viro nd->last_type = type; 14641da177e4SLinus Torvalds return 0; 14651da177e4SLinus Torvalds } 1466951361f9SAl Viro terminate_walk(nd); 14671da177e4SLinus Torvalds return err; 14681da177e4SLinus Torvalds } 14691da177e4SLinus Torvalds 147070e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 147170e9b357SAl Viro struct nameidata *nd, struct file **fp) 147231e6b01fSNick Piggin { 147331e6b01fSNick Piggin int retval = 0; 147431e6b01fSNick Piggin int fput_needed; 147531e6b01fSNick Piggin struct file *file; 147631e6b01fSNick Piggin 147731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 147816c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 147931e6b01fSNick Piggin nd->depth = 0; 148031e6b01fSNick Piggin nd->root.mnt = NULL; 148131e6b01fSNick Piggin 148231e6b01fSNick Piggin if (*name=='/') { 1483e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 148431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 148531e6b01fSNick Piggin rcu_read_lock(); 1486e41f7d4eSAl Viro set_root_rcu(nd); 1487e41f7d4eSAl Viro } else { 1488e41f7d4eSAl Viro set_root(nd); 1489e41f7d4eSAl Viro path_get(&nd->root); 1490e41f7d4eSAl Viro } 149131e6b01fSNick Piggin nd->path = nd->root; 149231e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1493e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 149431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1495c28cc364SNick Piggin unsigned seq; 149631e6b01fSNick Piggin 149731e6b01fSNick Piggin br_read_lock(vfsmount_lock); 149831e6b01fSNick Piggin rcu_read_lock(); 149931e6b01fSNick Piggin 1500c28cc364SNick Piggin do { 1501c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 150231e6b01fSNick Piggin nd->path = fs->pwd; 1503c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1504c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1505e41f7d4eSAl Viro } else { 1506e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1507e41f7d4eSAl Viro } 150831e6b01fSNick Piggin } else { 150931e6b01fSNick Piggin struct dentry *dentry; 151031e6b01fSNick Piggin 151131e6b01fSNick Piggin file = fget_light(dfd, &fput_needed); 151231e6b01fSNick Piggin retval = -EBADF; 151331e6b01fSNick Piggin if (!file) 151431e6b01fSNick Piggin goto out_fail; 151531e6b01fSNick Piggin 151631e6b01fSNick Piggin dentry = file->f_path.dentry; 151731e6b01fSNick Piggin 151831e6b01fSNick Piggin retval = -ENOTDIR; 151931e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 152031e6b01fSNick Piggin goto fput_fail; 152131e6b01fSNick Piggin 152231e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 152331e6b01fSNick Piggin if (retval) 152431e6b01fSNick Piggin goto fput_fail; 152531e6b01fSNick Piggin 152631e6b01fSNick Piggin nd->path = file->f_path; 1527e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 152831e6b01fSNick Piggin if (fput_needed) 152970e9b357SAl Viro *fp = file; 1530c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 153131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 153231e6b01fSNick Piggin rcu_read_lock(); 15335590ff0dSUlrich Drepper } else { 15345dd784d0SJan Blunck path_get(&file->f_path); 15355590ff0dSUlrich Drepper fput_light(file, fput_needed); 15361da177e4SLinus Torvalds } 1537e41f7d4eSAl Viro } 1538e41f7d4eSAl Viro 153931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15409b4a9b14SAl Viro return 0; 15412dfdd266SJosef 'Jeff' Sipek 15429b4a9b14SAl Viro fput_fail: 15439b4a9b14SAl Viro fput_light(file, fput_needed); 15449b4a9b14SAl Viro out_fail: 15459b4a9b14SAl Viro return retval; 15469b4a9b14SAl Viro } 15479b4a9b14SAl Viro 15489b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1549ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15509b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15519b4a9b14SAl Viro { 155270e9b357SAl Viro struct file *base = NULL; 155331e6b01fSNick Piggin int retval; 155431e6b01fSNick Piggin 155531e6b01fSNick Piggin /* 155631e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 155731e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 155831e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 155931e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 156031e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 156131e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 156231e6b01fSNick Piggin * analogue, foo_rcu(). 156331e6b01fSNick Piggin * 156431e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 156531e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 156631e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 156731e6b01fSNick Piggin * be able to complete). 156831e6b01fSNick Piggin */ 156970e9b357SAl Viro retval = path_init(dfd, name, flags, nd, &base); 1570ee0827cdSAl Viro 157131e6b01fSNick Piggin if (unlikely(retval)) 157231e6b01fSNick Piggin return retval; 1573ee0827cdSAl Viro 1574ee0827cdSAl Viro current->total_link_count = 0; 1575ee0827cdSAl Viro retval = link_path_walk(name, nd); 1576ee0827cdSAl Viro 1577ee0827cdSAl Viro if (nd->flags & LOOKUP_RCU) { 15784455ca62SAl Viro /* went all way through without dropping RCU */ 15794455ca62SAl Viro BUG_ON(retval); 1580086e183aSAl Viro if (nameidata_drop_rcu_last(nd)) 1581086e183aSAl Viro retval = -ECHILD; 1582086e183aSAl Viro } 158331e6b01fSNick Piggin 158416c2cd71SAl Viro if (!retval) 158516c2cd71SAl Viro retval = handle_reval_path(nd); 158616c2cd71SAl Viro 158770e9b357SAl Viro if (base) 158870e9b357SAl Viro fput(base); 1589ee0827cdSAl Viro 159031e6b01fSNick Piggin if (nd->root.mnt) { 159131e6b01fSNick Piggin path_put(&nd->root); 159231e6b01fSNick Piggin nd->root.mnt = NULL; 159331e6b01fSNick Piggin } 1594ee0827cdSAl Viro return retval; 159531e6b01fSNick Piggin } 159631e6b01fSNick Piggin 1597ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1598ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1599ee0827cdSAl Viro { 1600ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1601ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1602ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1603ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1604ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1605ee0827cdSAl Viro 160631e6b01fSNick Piggin if (likely(!retval)) { 160731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 160831e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 160931e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 161031e6b01fSNick Piggin } 161131e6b01fSNick Piggin } 1612170aa3d0SUlrich Drepper return retval; 16131da177e4SLinus Torvalds } 16141da177e4SLinus Torvalds 1615c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16165590ff0dSUlrich Drepper { 1617c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16185590ff0dSUlrich Drepper } 16195590ff0dSUlrich Drepper 1620d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1621d1811465SAl Viro { 1622d1811465SAl Viro struct nameidata nd; 1623d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1624d1811465SAl Viro if (!res) 1625d1811465SAl Viro *path = nd.path; 1626d1811465SAl Viro return res; 1627d1811465SAl Viro } 1628d1811465SAl Viro 162916f18200SJosef 'Jeff' Sipek /** 163016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 163116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 163216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 163316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 163416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 163516f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 163616f18200SJosef 'Jeff' Sipek */ 163716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 163816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 163916f18200SJosef 'Jeff' Sipek struct nameidata *nd) 164016f18200SJosef 'Jeff' Sipek { 1641ee0827cdSAl Viro int result; 164216f18200SJosef 'Jeff' Sipek 164316f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 164416f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 164516c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 164616f18200SJosef 'Jeff' Sipek nd->depth = 0; 164716f18200SJosef 'Jeff' Sipek 1648c8e7f449SJan Blunck nd->path.dentry = dentry; 1649c8e7f449SJan Blunck nd->path.mnt = mnt; 1650c8e7f449SJan Blunck path_get(&nd->path); 16515b857119SAl Viro nd->root = nd->path; 16525b857119SAl Viro path_get(&nd->root); 165331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 165416f18200SJosef 'Jeff' Sipek 1655ee0827cdSAl Viro current->total_link_count = 0; 1656ee0827cdSAl Viro 1657ee0827cdSAl Viro result = link_path_walk(name, nd); 165816c2cd71SAl Viro if (!result) 165916c2cd71SAl Viro result = handle_reval_path(nd); 1660ee0827cdSAl Viro if (result == -ESTALE) { 1661ee0827cdSAl Viro /* nd->path had been dropped */ 1662ee0827cdSAl Viro current->total_link_count = 0; 1663ee0827cdSAl Viro nd->path.dentry = dentry; 1664ee0827cdSAl Viro nd->path.mnt = mnt; 1665ee0827cdSAl Viro nd->inode = dentry->d_inode; 1666ee0827cdSAl Viro path_get(&nd->path); 166716c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_REVAL; 166816c2cd71SAl Viro 1669ee0827cdSAl Viro result = link_path_walk(name, nd); 167016c2cd71SAl Viro if (!result) 167116c2cd71SAl Viro result = handle_reval_path(nd); 1672ee0827cdSAl Viro } 1673ee0827cdSAl Viro if (unlikely(!result && !audit_dummy_context() && nd->path.dentry && 167431e6b01fSNick Piggin nd->inode)) 16754ac91378SJan Blunck audit_inode(name, nd->path.dentry); 167616f18200SJosef 'Jeff' Sipek 16772a737871SAl Viro path_put(&nd->root); 16782a737871SAl Viro nd->root.mnt = NULL; 167916f18200SJosef 'Jeff' Sipek 1680ee0827cdSAl Viro return result; 168116f18200SJosef 'Jeff' Sipek } 168216f18200SJosef 'Jeff' Sipek 1683eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1684eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16851da177e4SLinus Torvalds { 168681fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16871da177e4SLinus Torvalds struct dentry *dentry; 16881da177e4SLinus Torvalds int err; 16891da177e4SLinus Torvalds 1690b74c79e9SNick Piggin err = exec_permission(inode, 0); 169181fca444SChristoph Hellwig if (err) 169281fca444SChristoph Hellwig return ERR_PTR(err); 16931da177e4SLinus Torvalds 16941da177e4SLinus Torvalds /* 1695b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1696b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1697b04f784eSNick Piggin * a double lookup. 16986e6b1bd1SAl Viro */ 16996e6b1bd1SAl Viro dentry = d_lookup(base, name); 17006e6b1bd1SAl Viro 1701fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 17026e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 17036e6b1bd1SAl Viro 17041da177e4SLinus Torvalds if (!dentry) 1705baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17065a202bcdSAl Viro 17071da177e4SLinus Torvalds return dentry; 17081da177e4SLinus Torvalds } 17091da177e4SLinus Torvalds 1710057f6c01SJames Morris /* 1711057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1712057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1713057f6c01SJames Morris * SMP-safe. 1714057f6c01SJames Morris */ 1715a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17161da177e4SLinus Torvalds { 17174ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17181da177e4SLinus Torvalds } 17191da177e4SLinus Torvalds 1720eead1911SChristoph Hellwig /** 1721a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1722eead1911SChristoph Hellwig * @name: pathname component to lookup 1723eead1911SChristoph Hellwig * @base: base directory to lookup from 1724eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1725eead1911SChristoph Hellwig * 1726a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1727a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1728eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1729eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1730eead1911SChristoph Hellwig */ 1731057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1732057f6c01SJames Morris { 1733057f6c01SJames Morris struct qstr this; 17346a96ba54SAl Viro unsigned long hash; 17356a96ba54SAl Viro unsigned int c; 1736057f6c01SJames Morris 17372f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17382f9092e1SDavid Woodhouse 17396a96ba54SAl Viro this.name = name; 17406a96ba54SAl Viro this.len = len; 17416a96ba54SAl Viro if (!len) 17426a96ba54SAl Viro return ERR_PTR(-EACCES); 17436a96ba54SAl Viro 17446a96ba54SAl Viro hash = init_name_hash(); 17456a96ba54SAl Viro while (len--) { 17466a96ba54SAl Viro c = *(const unsigned char *)name++; 17476a96ba54SAl Viro if (c == '/' || c == '\0') 17486a96ba54SAl Viro return ERR_PTR(-EACCES); 17496a96ba54SAl Viro hash = partial_name_hash(c, hash); 17506a96ba54SAl Viro } 17516a96ba54SAl Viro this.hash = end_name_hash(hash); 17525a202bcdSAl Viro /* 17535a202bcdSAl Viro * See if the low-level filesystem might want 17545a202bcdSAl Viro * to use its own hash.. 17555a202bcdSAl Viro */ 17565a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17575a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17585a202bcdSAl Viro if (err < 0) 17595a202bcdSAl Viro return ERR_PTR(err); 17605a202bcdSAl Viro } 1761eead1911SChristoph Hellwig 176249705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1763057f6c01SJames Morris } 1764057f6c01SJames Morris 17652d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 17662d8f3038SAl Viro struct path *path) 17671da177e4SLinus Torvalds { 17682d8f3038SAl Viro struct nameidata nd; 17691da177e4SLinus Torvalds char *tmp = getname(name); 17701da177e4SLinus Torvalds int err = PTR_ERR(tmp); 17711da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 17722d8f3038SAl Viro 17732d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 17742d8f3038SAl Viro 17752d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 17761da177e4SLinus Torvalds putname(tmp); 17772d8f3038SAl Viro if (!err) 17782d8f3038SAl Viro *path = nd.path; 17791da177e4SLinus Torvalds } 17801da177e4SLinus Torvalds return err; 17811da177e4SLinus Torvalds } 17821da177e4SLinus Torvalds 17832ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 17842ad94ae6SAl Viro struct nameidata *nd, char **name) 17852ad94ae6SAl Viro { 17862ad94ae6SAl Viro char *s = getname(path); 17872ad94ae6SAl Viro int error; 17882ad94ae6SAl Viro 17892ad94ae6SAl Viro if (IS_ERR(s)) 17902ad94ae6SAl Viro return PTR_ERR(s); 17912ad94ae6SAl Viro 17922ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 17932ad94ae6SAl Viro if (error) 17942ad94ae6SAl Viro putname(s); 17952ad94ae6SAl Viro else 17962ad94ae6SAl Viro *name = s; 17972ad94ae6SAl Viro 17982ad94ae6SAl Viro return error; 17992ad94ae6SAl Viro } 18002ad94ae6SAl Viro 18011da177e4SLinus Torvalds /* 18021da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18031da177e4SLinus Torvalds * minimal. 18041da177e4SLinus Torvalds */ 18051da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18061da177e4SLinus Torvalds { 1807da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1808da9592edSDavid Howells 18091da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18101da177e4SLinus Torvalds return 0; 1811da9592edSDavid Howells if (inode->i_uid == fsuid) 18121da177e4SLinus Torvalds return 0; 1813da9592edSDavid Howells if (dir->i_uid == fsuid) 18141da177e4SLinus Torvalds return 0; 18151da177e4SLinus Torvalds return !capable(CAP_FOWNER); 18161da177e4SLinus Torvalds } 18171da177e4SLinus Torvalds 18181da177e4SLinus Torvalds /* 18191da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18201da177e4SLinus Torvalds * whether the type of victim is right. 18211da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18221da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18231da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18241da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18251da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18261da177e4SLinus Torvalds * a. be owner of dir, or 18271da177e4SLinus Torvalds * b. be owner of victim, or 18281da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18291da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18301da177e4SLinus Torvalds * links pointing to it. 18311da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18321da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18331da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18341da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18351da177e4SLinus Torvalds * nfs_async_unlink(). 18361da177e4SLinus Torvalds */ 1837858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18381da177e4SLinus Torvalds { 18391da177e4SLinus Torvalds int error; 18401da177e4SLinus Torvalds 18411da177e4SLinus Torvalds if (!victim->d_inode) 18421da177e4SLinus Torvalds return -ENOENT; 18431da177e4SLinus Torvalds 18441da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1845cccc6bbaSAl Viro audit_inode_child(victim, dir); 18461da177e4SLinus Torvalds 1847f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18481da177e4SLinus Torvalds if (error) 18491da177e4SLinus Torvalds return error; 18501da177e4SLinus Torvalds if (IS_APPEND(dir)) 18511da177e4SLinus Torvalds return -EPERM; 18521da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1853f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18541da177e4SLinus Torvalds return -EPERM; 18551da177e4SLinus Torvalds if (isdir) { 18561da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18571da177e4SLinus Torvalds return -ENOTDIR; 18581da177e4SLinus Torvalds if (IS_ROOT(victim)) 18591da177e4SLinus Torvalds return -EBUSY; 18601da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 18611da177e4SLinus Torvalds return -EISDIR; 18621da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18631da177e4SLinus Torvalds return -ENOENT; 18641da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 18651da177e4SLinus Torvalds return -EBUSY; 18661da177e4SLinus Torvalds return 0; 18671da177e4SLinus Torvalds } 18681da177e4SLinus Torvalds 18691da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 18701da177e4SLinus Torvalds * dir. 18711da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 18721da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 18731da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 18741da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 18751da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 18761da177e4SLinus Torvalds */ 1877a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 18781da177e4SLinus Torvalds { 18791da177e4SLinus Torvalds if (child->d_inode) 18801da177e4SLinus Torvalds return -EEXIST; 18811da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 18821da177e4SLinus Torvalds return -ENOENT; 1883f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 18841da177e4SLinus Torvalds } 18851da177e4SLinus Torvalds 18861da177e4SLinus Torvalds /* 18871da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 18881da177e4SLinus Torvalds */ 18891da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 18901da177e4SLinus Torvalds { 18911da177e4SLinus Torvalds struct dentry *p; 18921da177e4SLinus Torvalds 18931da177e4SLinus Torvalds if (p1 == p2) { 1894f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 18951da177e4SLinus Torvalds return NULL; 18961da177e4SLinus Torvalds } 18971da177e4SLinus Torvalds 1898a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 18991da177e4SLinus Torvalds 1900e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1901e2761a11SOGAWA Hirofumi if (p) { 1902f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1903f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19041da177e4SLinus Torvalds return p; 19051da177e4SLinus Torvalds } 19061da177e4SLinus Torvalds 1907e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1908e2761a11SOGAWA Hirofumi if (p) { 1909f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1910f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19111da177e4SLinus Torvalds return p; 19121da177e4SLinus Torvalds } 19131da177e4SLinus Torvalds 1914f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1915f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19161da177e4SLinus Torvalds return NULL; 19171da177e4SLinus Torvalds } 19181da177e4SLinus Torvalds 19191da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19201da177e4SLinus Torvalds { 19211b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19221da177e4SLinus Torvalds if (p1 != p2) { 19231b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1924a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19251da177e4SLinus Torvalds } 19261da177e4SLinus Torvalds } 19271da177e4SLinus Torvalds 19281da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19291da177e4SLinus Torvalds struct nameidata *nd) 19301da177e4SLinus Torvalds { 1931a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19321da177e4SLinus Torvalds 19331da177e4SLinus Torvalds if (error) 19341da177e4SLinus Torvalds return error; 19351da177e4SLinus Torvalds 1936acfa4380SAl Viro if (!dir->i_op->create) 19371da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19381da177e4SLinus Torvalds mode &= S_IALLUGO; 19391da177e4SLinus Torvalds mode |= S_IFREG; 19401da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19411da177e4SLinus Torvalds if (error) 19421da177e4SLinus Torvalds return error; 19431da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1944a74574aaSStephen Smalley if (!error) 1945f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19461da177e4SLinus Torvalds return error; 19471da177e4SLinus Torvalds } 19481da177e4SLinus Torvalds 19493fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 19501da177e4SLinus Torvalds { 19513fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19521da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19531da177e4SLinus Torvalds int error; 19541da177e4SLinus Torvalds 19551da177e4SLinus Torvalds if (!inode) 19561da177e4SLinus Torvalds return -ENOENT; 19571da177e4SLinus Torvalds 1958c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1959c8fe8f30SChristoph Hellwig case S_IFLNK: 19601da177e4SLinus Torvalds return -ELOOP; 1961c8fe8f30SChristoph Hellwig case S_IFDIR: 1962c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 19631da177e4SLinus Torvalds return -EISDIR; 1964c8fe8f30SChristoph Hellwig break; 1965c8fe8f30SChristoph Hellwig case S_IFBLK: 1966c8fe8f30SChristoph Hellwig case S_IFCHR: 19673fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 19681da177e4SLinus Torvalds return -EACCES; 1969c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1970c8fe8f30SChristoph Hellwig case S_IFIFO: 1971c8fe8f30SChristoph Hellwig case S_IFSOCK: 19721da177e4SLinus Torvalds flag &= ~O_TRUNC; 1973c8fe8f30SChristoph Hellwig break; 19744a3fd211SDave Hansen } 1975b41572e9SDave Hansen 19763fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1977b41572e9SDave Hansen if (error) 1978b41572e9SDave Hansen return error; 19796146f0d5SMimi Zohar 19801da177e4SLinus Torvalds /* 19811da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 19821da177e4SLinus Torvalds */ 19831da177e4SLinus Torvalds if (IS_APPEND(inode)) { 19848737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 19857715b521SAl Viro return -EPERM; 19861da177e4SLinus Torvalds if (flag & O_TRUNC) 19877715b521SAl Viro return -EPERM; 19881da177e4SLinus Torvalds } 19891da177e4SLinus Torvalds 19901da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 19917715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 19927715b521SAl Viro return -EPERM; 19931da177e4SLinus Torvalds 19941da177e4SLinus Torvalds /* 19951da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 19961da177e4SLinus Torvalds */ 1997b65a9cfcSAl Viro return break_lease(inode, flag); 19987715b521SAl Viro } 19997715b521SAl Viro 2000e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20017715b521SAl Viro { 2002e1181ee6SJeff Layton struct path *path = &filp->f_path; 20037715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20047715b521SAl Viro int error = get_write_access(inode); 20051da177e4SLinus Torvalds if (error) 20067715b521SAl Viro return error; 20071da177e4SLinus Torvalds /* 20081da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20091da177e4SLinus Torvalds */ 20101da177e4SLinus Torvalds error = locks_verify_locked(inode); 2011be6d3e56SKentaro Takeda if (!error) 2012ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20131da177e4SLinus Torvalds if (!error) { 20147715b521SAl Viro error = do_truncate(path->dentry, 0, 2015d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2016e1181ee6SJeff Layton filp); 20171da177e4SLinus Torvalds } 20181da177e4SLinus Torvalds put_write_access(inode); 2019acd0c935SMimi Zohar return error; 20201da177e4SLinus Torvalds } 20211da177e4SLinus Torvalds 2022d57999e1SDave Hansen /* 2023d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2024d57999e1SDave Hansen * 00 - read-only 2025d57999e1SDave Hansen * 01 - write-only 2026d57999e1SDave Hansen * 10 - read-write 2027d57999e1SDave Hansen * 11 - special 2028d57999e1SDave Hansen * it is changed into 2029d57999e1SDave Hansen * 00 - no permissions needed 2030d57999e1SDave Hansen * 01 - read-permission 2031d57999e1SDave Hansen * 10 - write-permission 2032d57999e1SDave Hansen * 11 - read-write 2033d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2034d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2035d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2036d57999e1SDave Hansen * later). 2037d57999e1SDave Hansen * 2038d57999e1SDave Hansen */ 2039d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2040d57999e1SDave Hansen { 2041d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2042d57999e1SDave Hansen flag++; 2043d57999e1SDave Hansen return flag; 2044d57999e1SDave Hansen } 2045d57999e1SDave Hansen 204631e6b01fSNick Piggin /* 2047fe2d35ffSAl Viro * Handle the last step of open() 204831e6b01fSNick Piggin */ 2049fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2050c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2051fb1cc555SAl Viro { 2052a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20536c0d46c4SAl Viro struct dentry *dentry; 2054ca344a89SAl Viro int open_flag = op->open_flag; 20556c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2056ca344a89SAl Viro int want_write = 0; 2057ca344a89SAl Viro int skip_perm = 0; 2058fb1cc555SAl Viro struct file *filp; 2059fe2d35ffSAl Viro struct inode *inode; 206016c2cd71SAl Viro int error; 2061fb1cc555SAl Viro 2062c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2063c3e380b0SAl Viro nd->flags |= op->intent; 2064c3e380b0SAl Viro 20651f36f774SAl Viro switch (nd->last_type) { 20661f36f774SAl Viro case LAST_DOTDOT: 2067176306f5SNeil Brown case LAST_DOT: 2068fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2069fe2d35ffSAl Viro if (error) 2070fe2d35ffSAl Viro return ERR_PTR(error); 20711f36f774SAl Viro /* fallthrough */ 20721f36f774SAl Viro case LAST_ROOT: 2073fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2074fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2075fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2076fe2d35ffSAl Viro } 207716c2cd71SAl Viro error = handle_reval_path(nd); 207816c2cd71SAl Viro if (error) 207916c2cd71SAl Viro goto exit; 2080fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2081ca344a89SAl Viro if (open_flag & O_CREAT) { 208216c2cd71SAl Viro error = -EISDIR; 20831f36f774SAl Viro goto exit; 2084fe2d35ffSAl Viro } 2085fe2d35ffSAl Viro goto ok; 20861f36f774SAl Viro case LAST_BIND: 2087fe2d35ffSAl Viro /* can't be RCU mode here */ 208816c2cd71SAl Viro error = handle_reval_path(nd); 208916c2cd71SAl Viro if (error) 209016c2cd71SAl Viro goto exit; 20911f36f774SAl Viro audit_inode(pathname, dir); 20921f36f774SAl Viro goto ok; 20931f36f774SAl Viro } 2094a2c36b45SAl Viro 2095ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2096fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2097fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2098fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2099fe2d35ffSAl Viro error = do_lookup(nd, &nd->last, path, &inode); 2100fe2d35ffSAl Viro if (error) { 2101fe2d35ffSAl Viro terminate_walk(nd); 2102fe2d35ffSAl Viro return ERR_PTR(error); 2103fe2d35ffSAl Viro } 2104fe2d35ffSAl Viro if (!inode) { 2105fe2d35ffSAl Viro path_to_nameidata(path, nd); 2106fe2d35ffSAl Viro terminate_walk(nd); 2107fe2d35ffSAl Viro return ERR_PTR(-ENOENT); 2108fe2d35ffSAl Viro } 2109fe2d35ffSAl Viro if (unlikely(inode->i_op->follow_link)) { 2110fe2d35ffSAl Viro /* We drop rcu-walk here */ 2111fe2d35ffSAl Viro if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry)) 2112fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2113fe2d35ffSAl Viro return NULL; 2114fe2d35ffSAl Viro } 2115fe2d35ffSAl Viro path_to_nameidata(path, nd); 2116fe2d35ffSAl Viro nd->inode = inode; 2117fe2d35ffSAl Viro /* sayonara */ 2118fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2119fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2120fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2121fe2d35ffSAl Viro } 2122fe2d35ffSAl Viro 2123fe2d35ffSAl Viro error = -ENOTDIR; 2124fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2125fe2d35ffSAl Viro if (!inode->i_op->lookup) 2126fe2d35ffSAl Viro goto exit; 2127fe2d35ffSAl Viro } 2128fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2129fe2d35ffSAl Viro goto ok; 2130fe2d35ffSAl Viro } 2131fe2d35ffSAl Viro 2132fe2d35ffSAl Viro /* create side of things */ 2133fe2d35ffSAl Viro 2134fe2d35ffSAl Viro if (nd->flags & LOOKUP_RCU) { 2135fe2d35ffSAl Viro if (nameidata_drop_rcu_last(nd)) 2136fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2137fe2d35ffSAl Viro } 2138fe2d35ffSAl Viro 2139fe2d35ffSAl Viro audit_inode(pathname, dir); 214016c2cd71SAl Viro error = -EISDIR; 21411f36f774SAl Viro /* trailing slashes? */ 214231e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21431f36f774SAl Viro goto exit; 21441f36f774SAl Viro 2145a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2146a1e28038SAl Viro 21476c0d46c4SAl Viro dentry = lookup_hash(nd); 21486c0d46c4SAl Viro error = PTR_ERR(dentry); 21496c0d46c4SAl Viro if (IS_ERR(dentry)) { 2150fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2151fb1cc555SAl Viro goto exit; 2152fb1cc555SAl Viro } 2153fb1cc555SAl Viro 21546c0d46c4SAl Viro path->dentry = dentry; 21556c0d46c4SAl Viro path->mnt = nd->path.mnt; 21566c0d46c4SAl Viro 2157fb1cc555SAl Viro /* Negative dentry, just create the file */ 21586c0d46c4SAl Viro if (!dentry->d_inode) { 21596c0d46c4SAl Viro int mode = op->mode; 21606c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21616c0d46c4SAl Viro mode &= ~current_umask(); 2162fb1cc555SAl Viro /* 2163fb1cc555SAl Viro * This write is needed to ensure that a 21646c0d46c4SAl Viro * rw->ro transition does not occur between 2165fb1cc555SAl Viro * the time when the file is created and when 2166fb1cc555SAl Viro * a permanent write count is taken through 2167fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2168fb1cc555SAl Viro */ 2169fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2170fb1cc555SAl Viro if (error) 2171fb1cc555SAl Viro goto exit_mutex_unlock; 2172ca344a89SAl Viro want_write = 1; 21739b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2174ca344a89SAl Viro open_flag &= ~O_TRUNC; 21756c0d46c4SAl Viro will_truncate = 0; 2176ca344a89SAl Viro skip_perm = 1; 21776c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 21786c0d46c4SAl Viro if (error) 21796c0d46c4SAl Viro goto exit_mutex_unlock; 21806c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 21816c0d46c4SAl Viro if (error) 21826c0d46c4SAl Viro goto exit_mutex_unlock; 21836c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 21846c0d46c4SAl Viro dput(nd->path.dentry); 21856c0d46c4SAl Viro nd->path.dentry = dentry; 2186ca344a89SAl Viro goto common; 2187fb1cc555SAl Viro } 2188fb1cc555SAl Viro 2189fb1cc555SAl Viro /* 2190fb1cc555SAl Viro * It already exists. 2191fb1cc555SAl Viro */ 2192fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2193fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2194fb1cc555SAl Viro 2195fb1cc555SAl Viro error = -EEXIST; 2196ca344a89SAl Viro if (open_flag & O_EXCL) 2197fb1cc555SAl Viro goto exit_dput; 2198fb1cc555SAl Viro 21999875cf80SDavid Howells error = follow_managed(path, nd->flags); 22009875cf80SDavid Howells if (error < 0) 2201fb1cc555SAl Viro goto exit_dput; 2202fb1cc555SAl Viro 2203fb1cc555SAl Viro error = -ENOENT; 2204fb1cc555SAl Viro if (!path->dentry->d_inode) 2205fb1cc555SAl Viro goto exit_dput; 22069e67f361SAl Viro 22079e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2208fb1cc555SAl Viro return NULL; 2209fb1cc555SAl Viro 2210fb1cc555SAl Viro path_to_nameidata(path, nd); 221131e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2212fb1cc555SAl Viro error = -EISDIR; 221331e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2214fb1cc555SAl Viro goto exit; 221567ee3ad2SAl Viro ok: 22166c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22176c0d46c4SAl Viro will_truncate = 0; 22186c0d46c4SAl Viro 22190f9d1a10SAl Viro if (will_truncate) { 22200f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22210f9d1a10SAl Viro if (error) 22220f9d1a10SAl Viro goto exit; 2223ca344a89SAl Viro want_write = 1; 22240f9d1a10SAl Viro } 2225ca344a89SAl Viro common: 2226ca344a89SAl Viro error = may_open(&nd->path, skip_perm ? 0 : op->acc_mode, open_flag); 2227ca344a89SAl Viro if (error) 22280f9d1a10SAl Viro goto exit; 22290f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22300f9d1a10SAl Viro if (!IS_ERR(filp)) { 22310f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22320f9d1a10SAl Viro if (error) { 22330f9d1a10SAl Viro fput(filp); 22340f9d1a10SAl Viro filp = ERR_PTR(error); 22350f9d1a10SAl Viro } 22360f9d1a10SAl Viro } 22370f9d1a10SAl Viro if (!IS_ERR(filp)) { 22380f9d1a10SAl Viro if (will_truncate) { 22390f9d1a10SAl Viro error = handle_truncate(filp); 22400f9d1a10SAl Viro if (error) { 22410f9d1a10SAl Viro fput(filp); 22420f9d1a10SAl Viro filp = ERR_PTR(error); 22430f9d1a10SAl Viro } 22440f9d1a10SAl Viro } 22450f9d1a10SAl Viro } 2246ca344a89SAl Viro out: 2247ca344a89SAl Viro if (want_write) 22480f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22490f9d1a10SAl Viro path_put(&nd->path); 2250fb1cc555SAl Viro return filp; 2251fb1cc555SAl Viro 2252fb1cc555SAl Viro exit_mutex_unlock: 2253fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2254fb1cc555SAl Viro exit_dput: 2255fb1cc555SAl Viro path_put_conditional(path, nd); 2256fb1cc555SAl Viro exit: 2257ca344a89SAl Viro filp = ERR_PTR(error); 2258ca344a89SAl Viro goto out; 2259fb1cc555SAl Viro } 2260fb1cc555SAl Viro 226113aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 226247c805dcSAl Viro const struct open_flags *op, int flags) 22631da177e4SLinus Torvalds { 2264fe2d35ffSAl Viro struct file *base = NULL; 22654a3fd211SDave Hansen struct file *filp; 2266a70e65dfSChristoph Hellwig struct nameidata nd; 22679850c056SAl Viro struct path path; 22681da177e4SLinus Torvalds int count = 0; 226913aab428SAl Viro int error; 227031e6b01fSNick Piggin 227131e6b01fSNick Piggin filp = get_empty_filp(); 227231e6b01fSNick Piggin if (!filp) 227331e6b01fSNick Piggin return ERR_PTR(-ENFILE); 227431e6b01fSNick Piggin 227547c805dcSAl Viro filp->f_flags = op->open_flag; 227631e6b01fSNick Piggin nd.intent.open.file = filp; 227747c805dcSAl Viro nd.intent.open.flags = open_to_namei_flags(op->open_flag); 227847c805dcSAl Viro nd.intent.open.create_mode = op->mode; 227931e6b01fSNick Piggin 2280fe2d35ffSAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, &nd, &base); 228131e6b01fSNick Piggin if (unlikely(error)) 228213aab428SAl Viro goto out_filp; 228331e6b01fSNick Piggin 2284fe2d35ffSAl Viro current->total_link_count = 0; 2285fe2d35ffSAl Viro error = link_path_walk(pathname, &nd); 228631e6b01fSNick Piggin if (unlikely(error)) 228731e6b01fSNick Piggin goto out_filp; 22881da177e4SLinus Torvalds 228947c805dcSAl Viro filp = do_last(&nd, &path, op, pathname); 2290806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 22917b9337aaSNick Piggin struct path link = path; 22927b9337aaSNick Piggin struct inode *linki = link.dentry->d_inode; 2293def4af30SAl Viro void *cookie; 229440b39136SAl Viro if (!(nd.flags & LOOKUP_FOLLOW) || count++ == 32) { 229540b39136SAl Viro path_put_conditional(&path, &nd); 229640b39136SAl Viro path_put(&nd.path); 229740b39136SAl Viro filp = ERR_PTR(-ELOOP); 229840b39136SAl Viro break; 229940b39136SAl Viro } 2300806b681cSAl Viro /* 2301806b681cSAl Viro * This is subtle. Instead of calling do_follow_link() we do 2302806b681cSAl Viro * the thing by hands. The reason is that this way we have zero 2303806b681cSAl Viro * link_count and path_walk() (called from ->follow_link) 2304806b681cSAl Viro * honoring LOOKUP_PARENT. After that we have the parent and 2305806b681cSAl Viro * last component, i.e. we are in the same situation as after 2306806b681cSAl Viro * the first path_walk(). Well, almost - if the last component 2307806b681cSAl Viro * is normal we get its copy stored in nd->last.name and we will 2308806b681cSAl Viro * have to putname() it when we are done. Procfs-like symlinks 2309806b681cSAl Viro * just set LAST_BIND. 2310806b681cSAl Viro */ 2311806b681cSAl Viro nd.flags |= LOOKUP_PARENT; 2312c3e380b0SAl Viro nd.flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 23137b9337aaSNick Piggin error = __do_follow_link(&link, &nd, &cookie); 2314c3e380b0SAl Viro if (unlikely(error)) 2315f1afe9efSAl Viro filp = ERR_PTR(error); 2316c3e380b0SAl Viro else 231747c805dcSAl Viro filp = do_last(&nd, &path, op, pathname); 2318f1afe9efSAl Viro if (!IS_ERR(cookie) && linki->i_op->put_link) 23197b9337aaSNick Piggin linki->i_op->put_link(link.dentry, &nd, cookie); 23207b9337aaSNick Piggin path_put(&link); 2321806b681cSAl Viro } 232210fa8e62SAl Viro out: 23232a737871SAl Viro if (nd.root.mnt) 23242a737871SAl Viro path_put(&nd.root); 2325fe2d35ffSAl Viro if (base) 2326fe2d35ffSAl Viro fput(base); 23272dab5974SLinus Torvalds release_open_intent(&nd); 232810fa8e62SAl Viro return filp; 23291da177e4SLinus Torvalds 233031e6b01fSNick Piggin out_filp: 233110fa8e62SAl Viro filp = ERR_PTR(error); 233210fa8e62SAl Viro goto out; 2333de459215SKirill Korotaev } 23341da177e4SLinus Torvalds 233513aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 233613aab428SAl Viro const struct open_flags *op, int flags) 233713aab428SAl Viro { 233813aab428SAl Viro struct file *filp; 233913aab428SAl Viro 234013aab428SAl Viro filp = path_openat(dfd, pathname, op, flags | LOOKUP_RCU); 234113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 234213aab428SAl Viro filp = path_openat(dfd, pathname, op, flags); 234313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 234413aab428SAl Viro filp = path_openat(dfd, pathname, op, flags | LOOKUP_REVAL); 234513aab428SAl Viro return filp; 234613aab428SAl Viro } 234713aab428SAl Viro 23481da177e4SLinus Torvalds /** 23491da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 23501da177e4SLinus Torvalds * @nd: nameidata info 23511da177e4SLinus Torvalds * @is_dir: directory flag 23521da177e4SLinus Torvalds * 23531da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 23541da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2355c663e5d8SChristoph Hellwig * 23564ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 23571da177e4SLinus Torvalds */ 23581da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 23591da177e4SLinus Torvalds { 2360c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 23611da177e4SLinus Torvalds 23624ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2363c663e5d8SChristoph Hellwig /* 2364c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2365c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2366c663e5d8SChristoph Hellwig */ 23671da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 23681da177e4SLinus Torvalds goto fail; 23691da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 23703516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2371a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2372c663e5d8SChristoph Hellwig 2373c663e5d8SChristoph Hellwig /* 2374c663e5d8SChristoph Hellwig * Do the final lookup. 2375c663e5d8SChristoph Hellwig */ 237649705b77SChristoph Hellwig dentry = lookup_hash(nd); 23771da177e4SLinus Torvalds if (IS_ERR(dentry)) 23781da177e4SLinus Torvalds goto fail; 2379c663e5d8SChristoph Hellwig 2380e9baf6e5SAl Viro if (dentry->d_inode) 2381e9baf6e5SAl Viro goto eexist; 2382c663e5d8SChristoph Hellwig /* 2383c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2384c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2385c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2386c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2387c663e5d8SChristoph Hellwig */ 2388e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 23891da177e4SLinus Torvalds dput(dentry); 23901da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2391e9baf6e5SAl Viro } 2392e9baf6e5SAl Viro return dentry; 2393e9baf6e5SAl Viro eexist: 2394e9baf6e5SAl Viro dput(dentry); 2395e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 23961da177e4SLinus Torvalds fail: 23971da177e4SLinus Torvalds return dentry; 23981da177e4SLinus Torvalds } 2399f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 24001da177e4SLinus Torvalds 24011da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24021da177e4SLinus Torvalds { 2403a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24041da177e4SLinus Torvalds 24051da177e4SLinus Torvalds if (error) 24061da177e4SLinus Torvalds return error; 24071da177e4SLinus Torvalds 24081da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 24091da177e4SLinus Torvalds return -EPERM; 24101da177e4SLinus Torvalds 2411acfa4380SAl Viro if (!dir->i_op->mknod) 24121da177e4SLinus Torvalds return -EPERM; 24131da177e4SLinus Torvalds 241408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 241508ce5f16SSerge E. Hallyn if (error) 241608ce5f16SSerge E. Hallyn return error; 241708ce5f16SSerge E. Hallyn 24181da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24191da177e4SLinus Torvalds if (error) 24201da177e4SLinus Torvalds return error; 24211da177e4SLinus Torvalds 24221da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2423a74574aaSStephen Smalley if (!error) 2424f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24251da177e4SLinus Torvalds return error; 24261da177e4SLinus Torvalds } 24271da177e4SLinus Torvalds 2428463c3197SDave Hansen static int may_mknod(mode_t mode) 2429463c3197SDave Hansen { 2430463c3197SDave Hansen switch (mode & S_IFMT) { 2431463c3197SDave Hansen case S_IFREG: 2432463c3197SDave Hansen case S_IFCHR: 2433463c3197SDave Hansen case S_IFBLK: 2434463c3197SDave Hansen case S_IFIFO: 2435463c3197SDave Hansen case S_IFSOCK: 2436463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2437463c3197SDave Hansen return 0; 2438463c3197SDave Hansen case S_IFDIR: 2439463c3197SDave Hansen return -EPERM; 2440463c3197SDave Hansen default: 2441463c3197SDave Hansen return -EINVAL; 2442463c3197SDave Hansen } 2443463c3197SDave Hansen } 2444463c3197SDave Hansen 24452e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24462e4d0924SHeiko Carstens unsigned, dev) 24471da177e4SLinus Torvalds { 24482ad94ae6SAl Viro int error; 24491da177e4SLinus Torvalds char *tmp; 24501da177e4SLinus Torvalds struct dentry *dentry; 24511da177e4SLinus Torvalds struct nameidata nd; 24521da177e4SLinus Torvalds 24531da177e4SLinus Torvalds if (S_ISDIR(mode)) 24541da177e4SLinus Torvalds return -EPERM; 24551da177e4SLinus Torvalds 24562ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 24571da177e4SLinus Torvalds if (error) 24582ad94ae6SAl Viro return error; 24592ad94ae6SAl Viro 24601da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2461463c3197SDave Hansen if (IS_ERR(dentry)) { 24621da177e4SLinus Torvalds error = PTR_ERR(dentry); 2463463c3197SDave Hansen goto out_unlock; 2464463c3197SDave Hansen } 24654ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2466ce3b0f8dSAl Viro mode &= ~current_umask(); 2467463c3197SDave Hansen error = may_mknod(mode); 2468463c3197SDave Hansen if (error) 2469463c3197SDave Hansen goto out_dput; 2470463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2471463c3197SDave Hansen if (error) 2472463c3197SDave Hansen goto out_dput; 2473be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2474be6d3e56SKentaro Takeda if (error) 2475be6d3e56SKentaro Takeda goto out_drop_write; 24761da177e4SLinus Torvalds switch (mode & S_IFMT) { 24771da177e4SLinus Torvalds case 0: case S_IFREG: 24784ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 24791da177e4SLinus Torvalds break; 24801da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 24814ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 24821da177e4SLinus Torvalds new_decode_dev(dev)); 24831da177e4SLinus Torvalds break; 24841da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 24854ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 24861da177e4SLinus Torvalds break; 24871da177e4SLinus Torvalds } 2488be6d3e56SKentaro Takeda out_drop_write: 2489463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2490463c3197SDave Hansen out_dput: 24911da177e4SLinus Torvalds dput(dentry); 2492463c3197SDave Hansen out_unlock: 24934ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24941d957f9bSJan Blunck path_put(&nd.path); 24951da177e4SLinus Torvalds putname(tmp); 24961da177e4SLinus Torvalds 24971da177e4SLinus Torvalds return error; 24981da177e4SLinus Torvalds } 24991da177e4SLinus Torvalds 25003480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25015590ff0dSUlrich Drepper { 25025590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25035590ff0dSUlrich Drepper } 25045590ff0dSUlrich Drepper 25051da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25061da177e4SLinus Torvalds { 2507a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25081da177e4SLinus Torvalds 25091da177e4SLinus Torvalds if (error) 25101da177e4SLinus Torvalds return error; 25111da177e4SLinus Torvalds 2512acfa4380SAl Viro if (!dir->i_op->mkdir) 25131da177e4SLinus Torvalds return -EPERM; 25141da177e4SLinus Torvalds 25151da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25161da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25171da177e4SLinus Torvalds if (error) 25181da177e4SLinus Torvalds return error; 25191da177e4SLinus Torvalds 25201da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2521a74574aaSStephen Smalley if (!error) 2522f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25231da177e4SLinus Torvalds return error; 25241da177e4SLinus Torvalds } 25251da177e4SLinus Torvalds 25262e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25271da177e4SLinus Torvalds { 25281da177e4SLinus Torvalds int error = 0; 25291da177e4SLinus Torvalds char * tmp; 25306902d925SDave Hansen struct dentry *dentry; 25316902d925SDave Hansen struct nameidata nd; 25321da177e4SLinus Torvalds 25332ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 25342ad94ae6SAl Viro if (error) 25356902d925SDave Hansen goto out_err; 25361da177e4SLinus Torvalds 25371da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 25381da177e4SLinus Torvalds error = PTR_ERR(dentry); 25396902d925SDave Hansen if (IS_ERR(dentry)) 25406902d925SDave Hansen goto out_unlock; 25416902d925SDave Hansen 25424ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2543ce3b0f8dSAl Viro mode &= ~current_umask(); 2544463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2545463c3197SDave Hansen if (error) 2546463c3197SDave Hansen goto out_dput; 2547be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2548be6d3e56SKentaro Takeda if (error) 2549be6d3e56SKentaro Takeda goto out_drop_write; 25504ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2551be6d3e56SKentaro Takeda out_drop_write: 2552463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2553463c3197SDave Hansen out_dput: 25541da177e4SLinus Torvalds dput(dentry); 25556902d925SDave Hansen out_unlock: 25564ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25571d957f9bSJan Blunck path_put(&nd.path); 25581da177e4SLinus Torvalds putname(tmp); 25596902d925SDave Hansen out_err: 25601da177e4SLinus Torvalds return error; 25611da177e4SLinus Torvalds } 25621da177e4SLinus Torvalds 25633cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25645590ff0dSUlrich Drepper { 25655590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25665590ff0dSUlrich Drepper } 25675590ff0dSUlrich Drepper 25681da177e4SLinus Torvalds /* 25691da177e4SLinus Torvalds * We try to drop the dentry early: we should have 25701da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 25711da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 25721da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 25731da177e4SLinus Torvalds * 25741da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 25751da177e4SLinus Torvalds * do a 25761da177e4SLinus Torvalds * 25771da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 25781da177e4SLinus Torvalds * return -EBUSY; 25791da177e4SLinus Torvalds * 25801da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 25811da177e4SLinus Torvalds * that is still in use by something else.. 25821da177e4SLinus Torvalds */ 25831da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 25841da177e4SLinus Torvalds { 25851da177e4SLinus Torvalds dget(dentry); 25861da177e4SLinus Torvalds shrink_dcache_parent(dentry); 25871da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2588b7ab39f6SNick Piggin if (dentry->d_count == 2) 25891da177e4SLinus Torvalds __d_drop(dentry); 25901da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 25911da177e4SLinus Torvalds } 25921da177e4SLinus Torvalds 25931da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 25941da177e4SLinus Torvalds { 25951da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 25961da177e4SLinus Torvalds 25971da177e4SLinus Torvalds if (error) 25981da177e4SLinus Torvalds return error; 25991da177e4SLinus Torvalds 2600acfa4380SAl Viro if (!dir->i_op->rmdir) 26011da177e4SLinus Torvalds return -EPERM; 26021da177e4SLinus Torvalds 26031b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26041da177e4SLinus Torvalds dentry_unhash(dentry); 26051da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26061da177e4SLinus Torvalds error = -EBUSY; 26071da177e4SLinus Torvalds else { 26081da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 26091da177e4SLinus Torvalds if (!error) { 26101da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2611d83c49f3SAl Viro if (!error) { 26121da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2613d83c49f3SAl Viro dont_mount(dentry); 2614d83c49f3SAl Viro } 26151da177e4SLinus Torvalds } 26161da177e4SLinus Torvalds } 26171b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 26181da177e4SLinus Torvalds if (!error) { 26191da177e4SLinus Torvalds d_delete(dentry); 26201da177e4SLinus Torvalds } 26211da177e4SLinus Torvalds dput(dentry); 26221da177e4SLinus Torvalds 26231da177e4SLinus Torvalds return error; 26241da177e4SLinus Torvalds } 26251da177e4SLinus Torvalds 26265590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26271da177e4SLinus Torvalds { 26281da177e4SLinus Torvalds int error = 0; 26291da177e4SLinus Torvalds char * name; 26301da177e4SLinus Torvalds struct dentry *dentry; 26311da177e4SLinus Torvalds struct nameidata nd; 26321da177e4SLinus Torvalds 26332ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26341da177e4SLinus Torvalds if (error) 26352ad94ae6SAl Viro return error; 26361da177e4SLinus Torvalds 26371da177e4SLinus Torvalds switch(nd.last_type) { 26381da177e4SLinus Torvalds case LAST_DOTDOT: 26391da177e4SLinus Torvalds error = -ENOTEMPTY; 26401da177e4SLinus Torvalds goto exit1; 26411da177e4SLinus Torvalds case LAST_DOT: 26421da177e4SLinus Torvalds error = -EINVAL; 26431da177e4SLinus Torvalds goto exit1; 26441da177e4SLinus Torvalds case LAST_ROOT: 26451da177e4SLinus Torvalds error = -EBUSY; 26461da177e4SLinus Torvalds goto exit1; 26471da177e4SLinus Torvalds } 26480612d9fbSOGAWA Hirofumi 26490612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26500612d9fbSOGAWA Hirofumi 26514ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 265249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26531da177e4SLinus Torvalds error = PTR_ERR(dentry); 26546902d925SDave Hansen if (IS_ERR(dentry)) 26556902d925SDave Hansen goto exit2; 26560622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26570622753bSDave Hansen if (error) 26580622753bSDave Hansen goto exit3; 2659be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2660be6d3e56SKentaro Takeda if (error) 2661be6d3e56SKentaro Takeda goto exit4; 26624ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2663be6d3e56SKentaro Takeda exit4: 26640622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26650622753bSDave Hansen exit3: 26661da177e4SLinus Torvalds dput(dentry); 26676902d925SDave Hansen exit2: 26684ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26691da177e4SLinus Torvalds exit1: 26701d957f9bSJan Blunck path_put(&nd.path); 26711da177e4SLinus Torvalds putname(name); 26721da177e4SLinus Torvalds return error; 26731da177e4SLinus Torvalds } 26741da177e4SLinus Torvalds 26753cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 26765590ff0dSUlrich Drepper { 26775590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 26785590ff0dSUlrich Drepper } 26795590ff0dSUlrich Drepper 26801da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 26811da177e4SLinus Torvalds { 26821da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 26831da177e4SLinus Torvalds 26841da177e4SLinus Torvalds if (error) 26851da177e4SLinus Torvalds return error; 26861da177e4SLinus Torvalds 2687acfa4380SAl Viro if (!dir->i_op->unlink) 26881da177e4SLinus Torvalds return -EPERM; 26891da177e4SLinus Torvalds 26901b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 26911da177e4SLinus Torvalds if (d_mountpoint(dentry)) 26921da177e4SLinus Torvalds error = -EBUSY; 26931da177e4SLinus Torvalds else { 26941da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2695bec1052eSAl Viro if (!error) { 26961da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2697bec1052eSAl Viro if (!error) 2698d83c49f3SAl Viro dont_mount(dentry); 2699bec1052eSAl Viro } 27001da177e4SLinus Torvalds } 27011b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27021da177e4SLinus Torvalds 27031da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27041da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2705ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27061da177e4SLinus Torvalds d_delete(dentry); 27071da177e4SLinus Torvalds } 27080eeca283SRobert Love 27091da177e4SLinus Torvalds return error; 27101da177e4SLinus Torvalds } 27111da177e4SLinus Torvalds 27121da177e4SLinus Torvalds /* 27131da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27141b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27151da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27161da177e4SLinus Torvalds * while waiting on the I/O. 27171da177e4SLinus Torvalds */ 27185590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27191da177e4SLinus Torvalds { 27202ad94ae6SAl Viro int error; 27211da177e4SLinus Torvalds char *name; 27221da177e4SLinus Torvalds struct dentry *dentry; 27231da177e4SLinus Torvalds struct nameidata nd; 27241da177e4SLinus Torvalds struct inode *inode = NULL; 27251da177e4SLinus Torvalds 27262ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27271da177e4SLinus Torvalds if (error) 27282ad94ae6SAl Viro return error; 27292ad94ae6SAl Viro 27301da177e4SLinus Torvalds error = -EISDIR; 27311da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27321da177e4SLinus Torvalds goto exit1; 27330612d9fbSOGAWA Hirofumi 27340612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27350612d9fbSOGAWA Hirofumi 27364ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 273749705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27381da177e4SLinus Torvalds error = PTR_ERR(dentry); 27391da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27401da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 27411da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 27421da177e4SLinus Torvalds goto slashes; 27431da177e4SLinus Torvalds inode = dentry->d_inode; 27441da177e4SLinus Torvalds if (inode) 27457de9c6eeSAl Viro ihold(inode); 27460622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27470622753bSDave Hansen if (error) 27480622753bSDave Hansen goto exit2; 2749be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2750be6d3e56SKentaro Takeda if (error) 2751be6d3e56SKentaro Takeda goto exit3; 27524ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2753be6d3e56SKentaro Takeda exit3: 27540622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27551da177e4SLinus Torvalds exit2: 27561da177e4SLinus Torvalds dput(dentry); 27571da177e4SLinus Torvalds } 27584ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27591da177e4SLinus Torvalds if (inode) 27601da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27611da177e4SLinus Torvalds exit1: 27621d957f9bSJan Blunck path_put(&nd.path); 27631da177e4SLinus Torvalds putname(name); 27641da177e4SLinus Torvalds return error; 27651da177e4SLinus Torvalds 27661da177e4SLinus Torvalds slashes: 27671da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27681da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 27691da177e4SLinus Torvalds goto exit2; 27701da177e4SLinus Torvalds } 27711da177e4SLinus Torvalds 27722e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 27735590ff0dSUlrich Drepper { 27745590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 27755590ff0dSUlrich Drepper return -EINVAL; 27765590ff0dSUlrich Drepper 27775590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 27785590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 27795590ff0dSUlrich Drepper 27805590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 27815590ff0dSUlrich Drepper } 27825590ff0dSUlrich Drepper 27833480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 27845590ff0dSUlrich Drepper { 27855590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 27865590ff0dSUlrich Drepper } 27875590ff0dSUlrich Drepper 2788db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 27891da177e4SLinus Torvalds { 2790a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27911da177e4SLinus Torvalds 27921da177e4SLinus Torvalds if (error) 27931da177e4SLinus Torvalds return error; 27941da177e4SLinus Torvalds 2795acfa4380SAl Viro if (!dir->i_op->symlink) 27961da177e4SLinus Torvalds return -EPERM; 27971da177e4SLinus Torvalds 27981da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 27991da177e4SLinus Torvalds if (error) 28001da177e4SLinus Torvalds return error; 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2803a74574aaSStephen Smalley if (!error) 2804f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28051da177e4SLinus Torvalds return error; 28061da177e4SLinus Torvalds } 28071da177e4SLinus Torvalds 28082e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28092e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28101da177e4SLinus Torvalds { 28112ad94ae6SAl Viro int error; 28121da177e4SLinus Torvalds char *from; 28131da177e4SLinus Torvalds char *to; 28146902d925SDave Hansen struct dentry *dentry; 28156902d925SDave Hansen struct nameidata nd; 28161da177e4SLinus Torvalds 28171da177e4SLinus Torvalds from = getname(oldname); 28181da177e4SLinus Torvalds if (IS_ERR(from)) 28191da177e4SLinus Torvalds return PTR_ERR(from); 28202ad94ae6SAl Viro 28212ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 28222ad94ae6SAl Viro if (error) 28236902d925SDave Hansen goto out_putname; 28241da177e4SLinus Torvalds 28251da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 28261da177e4SLinus Torvalds error = PTR_ERR(dentry); 28276902d925SDave Hansen if (IS_ERR(dentry)) 28286902d925SDave Hansen goto out_unlock; 28296902d925SDave Hansen 283075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 283175c3f29dSDave Hansen if (error) 283275c3f29dSDave Hansen goto out_dput; 2833be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2834be6d3e56SKentaro Takeda if (error) 2835be6d3e56SKentaro Takeda goto out_drop_write; 2836db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2837be6d3e56SKentaro Takeda out_drop_write: 283875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 283975c3f29dSDave Hansen out_dput: 28401da177e4SLinus Torvalds dput(dentry); 28416902d925SDave Hansen out_unlock: 28424ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28431d957f9bSJan Blunck path_put(&nd.path); 28441da177e4SLinus Torvalds putname(to); 28456902d925SDave Hansen out_putname: 28461da177e4SLinus Torvalds putname(from); 28471da177e4SLinus Torvalds return error; 28481da177e4SLinus Torvalds } 28491da177e4SLinus Torvalds 28503480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28515590ff0dSUlrich Drepper { 28525590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28535590ff0dSUlrich Drepper } 28545590ff0dSUlrich Drepper 28551da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28561da177e4SLinus Torvalds { 28571da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28581da177e4SLinus Torvalds int error; 28591da177e4SLinus Torvalds 28601da177e4SLinus Torvalds if (!inode) 28611da177e4SLinus Torvalds return -ENOENT; 28621da177e4SLinus Torvalds 2863a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28641da177e4SLinus Torvalds if (error) 28651da177e4SLinus Torvalds return error; 28661da177e4SLinus Torvalds 28671da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28681da177e4SLinus Torvalds return -EXDEV; 28691da177e4SLinus Torvalds 28701da177e4SLinus Torvalds /* 28711da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 28721da177e4SLinus Torvalds */ 28731da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 28741da177e4SLinus Torvalds return -EPERM; 2875acfa4380SAl Viro if (!dir->i_op->link) 28761da177e4SLinus Torvalds return -EPERM; 28777e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 28781da177e4SLinus Torvalds return -EPERM; 28791da177e4SLinus Torvalds 28801da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 28811da177e4SLinus Torvalds if (error) 28821da177e4SLinus Torvalds return error; 28831da177e4SLinus Torvalds 28847e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 28851da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 28867e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2887e31e14ecSStephen Smalley if (!error) 28887e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 28891da177e4SLinus Torvalds return error; 28901da177e4SLinus Torvalds } 28911da177e4SLinus Torvalds 28921da177e4SLinus Torvalds /* 28931da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 28941da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 28951da177e4SLinus Torvalds * newname. --KAB 28961da177e4SLinus Torvalds * 28971da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 28981da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 28991da177e4SLinus Torvalds * and other special files. --ADM 29001da177e4SLinus Torvalds */ 29012e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29022e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29031da177e4SLinus Torvalds { 29041da177e4SLinus Torvalds struct dentry *new_dentry; 29052d8f3038SAl Viro struct nameidata nd; 29062d8f3038SAl Viro struct path old_path; 29071da177e4SLinus Torvalds int error; 29081da177e4SLinus Torvalds char *to; 29091da177e4SLinus Torvalds 291045c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2911c04030e1SUlrich Drepper return -EINVAL; 2912c04030e1SUlrich Drepper 29132d8f3038SAl Viro error = user_path_at(olddfd, oldname, 291445c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 29152d8f3038SAl Viro &old_path); 29161da177e4SLinus Torvalds if (error) 29172ad94ae6SAl Viro return error; 29182ad94ae6SAl Viro 29192ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 29201da177e4SLinus Torvalds if (error) 29211da177e4SLinus Torvalds goto out; 29221da177e4SLinus Torvalds error = -EXDEV; 29232d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 29241da177e4SLinus Torvalds goto out_release; 29251da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 29261da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29276902d925SDave Hansen if (IS_ERR(new_dentry)) 29286902d925SDave Hansen goto out_unlock; 292975c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 293075c3f29dSDave Hansen if (error) 293175c3f29dSDave Hansen goto out_dput; 2932be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2933be6d3e56SKentaro Takeda if (error) 2934be6d3e56SKentaro Takeda goto out_drop_write; 29352d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2936be6d3e56SKentaro Takeda out_drop_write: 293775c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 293875c3f29dSDave Hansen out_dput: 29391da177e4SLinus Torvalds dput(new_dentry); 29406902d925SDave Hansen out_unlock: 29414ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29421da177e4SLinus Torvalds out_release: 29431d957f9bSJan Blunck path_put(&nd.path); 29442ad94ae6SAl Viro putname(to); 29451da177e4SLinus Torvalds out: 29462d8f3038SAl Viro path_put(&old_path); 29471da177e4SLinus Torvalds 29481da177e4SLinus Torvalds return error; 29491da177e4SLinus Torvalds } 29501da177e4SLinus Torvalds 29513480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29525590ff0dSUlrich Drepper { 2953c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29545590ff0dSUlrich Drepper } 29555590ff0dSUlrich Drepper 29561da177e4SLinus Torvalds /* 29571da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29581da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29591da177e4SLinus Torvalds * Problems: 29601da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29611da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29621da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2963a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29641da177e4SLinus Torvalds * story. 29651da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29661b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29671da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29681da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2969a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 29701da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 29711da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 29721da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2973a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 29741da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 29751da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 29761da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 29771da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 29781da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 29791da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 29801da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 29811da177e4SLinus Torvalds * trick as in rmdir(). 29821da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 29831b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 29841da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 2985c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 29861da177e4SLinus Torvalds * locking]. 29871da177e4SLinus Torvalds */ 298875c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 29891da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 29901da177e4SLinus Torvalds { 29911da177e4SLinus Torvalds int error = 0; 29921da177e4SLinus Torvalds struct inode *target; 29931da177e4SLinus Torvalds 29941da177e4SLinus Torvalds /* 29951da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 29961da177e4SLinus Torvalds * we'll need to flip '..'. 29971da177e4SLinus Torvalds */ 29981da177e4SLinus Torvalds if (new_dir != old_dir) { 2999f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30001da177e4SLinus Torvalds if (error) 30011da177e4SLinus Torvalds return error; 30021da177e4SLinus Torvalds } 30031da177e4SLinus Torvalds 30041da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30051da177e4SLinus Torvalds if (error) 30061da177e4SLinus Torvalds return error; 30071da177e4SLinus Torvalds 30081da177e4SLinus Torvalds target = new_dentry->d_inode; 3009d83c49f3SAl Viro if (target) 30101b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30111da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30121da177e4SLinus Torvalds error = -EBUSY; 3013d83c49f3SAl Viro else { 3014d83c49f3SAl Viro if (target) 3015d83c49f3SAl Viro dentry_unhash(new_dentry); 30161da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3017d83c49f3SAl Viro } 30181da177e4SLinus Torvalds if (target) { 3019d83c49f3SAl Viro if (!error) { 30201da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3021d83c49f3SAl Viro dont_mount(new_dentry); 3022d83c49f3SAl Viro } 30231b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30241da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 30251da177e4SLinus Torvalds d_rehash(new_dentry); 30261da177e4SLinus Torvalds dput(new_dentry); 30271da177e4SLinus Torvalds } 3028e31e14ecSStephen Smalley if (!error) 3029349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30301da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30311da177e4SLinus Torvalds return error; 30321da177e4SLinus Torvalds } 30331da177e4SLinus Torvalds 303475c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30351da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30361da177e4SLinus Torvalds { 30371da177e4SLinus Torvalds struct inode *target; 30381da177e4SLinus Torvalds int error; 30391da177e4SLinus Torvalds 30401da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30411da177e4SLinus Torvalds if (error) 30421da177e4SLinus Torvalds return error; 30431da177e4SLinus Torvalds 30441da177e4SLinus Torvalds dget(new_dentry); 30451da177e4SLinus Torvalds target = new_dentry->d_inode; 30461da177e4SLinus Torvalds if (target) 30471b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30481da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 30491da177e4SLinus Torvalds error = -EBUSY; 30501da177e4SLinus Torvalds else 30511da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30521da177e4SLinus Torvalds if (!error) { 3053bec1052eSAl Viro if (target) 3054d83c49f3SAl Viro dont_mount(new_dentry); 3055349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30561da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 30571da177e4SLinus Torvalds } 30581da177e4SLinus Torvalds if (target) 30591b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30601da177e4SLinus Torvalds dput(new_dentry); 30611da177e4SLinus Torvalds return error; 30621da177e4SLinus Torvalds } 30631da177e4SLinus Torvalds 30641da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30651da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30661da177e4SLinus Torvalds { 30671da177e4SLinus Torvalds int error; 30681da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 306959b0df21SEric Paris const unsigned char *old_name; 30701da177e4SLinus Torvalds 30711da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 30721da177e4SLinus Torvalds return 0; 30731da177e4SLinus Torvalds 30741da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 30751da177e4SLinus Torvalds if (error) 30761da177e4SLinus Torvalds return error; 30771da177e4SLinus Torvalds 30781da177e4SLinus Torvalds if (!new_dentry->d_inode) 3079a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 30801da177e4SLinus Torvalds else 30811da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 30821da177e4SLinus Torvalds if (error) 30831da177e4SLinus Torvalds return error; 30841da177e4SLinus Torvalds 3085acfa4380SAl Viro if (!old_dir->i_op->rename) 30861da177e4SLinus Torvalds return -EPERM; 30871da177e4SLinus Torvalds 30880eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 30890eeca283SRobert Love 30901da177e4SLinus Torvalds if (is_dir) 30911da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 30921da177e4SLinus Torvalds else 30931da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3094123df294SAl Viro if (!error) 3095123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 30965a190ae6SAl Viro new_dentry->d_inode, old_dentry); 30970eeca283SRobert Love fsnotify_oldname_free(old_name); 30980eeca283SRobert Love 30991da177e4SLinus Torvalds return error; 31001da177e4SLinus Torvalds } 31011da177e4SLinus Torvalds 31022e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31032e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31041da177e4SLinus Torvalds { 31051da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31061da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31071da177e4SLinus Torvalds struct dentry *trap; 31081da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31092ad94ae6SAl Viro char *from; 31102ad94ae6SAl Viro char *to; 31112ad94ae6SAl Viro int error; 31121da177e4SLinus Torvalds 31132ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31141da177e4SLinus Torvalds if (error) 31151da177e4SLinus Torvalds goto exit; 31161da177e4SLinus Torvalds 31172ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31181da177e4SLinus Torvalds if (error) 31191da177e4SLinus Torvalds goto exit1; 31201da177e4SLinus Torvalds 31211da177e4SLinus Torvalds error = -EXDEV; 31224ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31231da177e4SLinus Torvalds goto exit2; 31241da177e4SLinus Torvalds 31254ac91378SJan Blunck old_dir = oldnd.path.dentry; 31261da177e4SLinus Torvalds error = -EBUSY; 31271da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31281da177e4SLinus Torvalds goto exit2; 31291da177e4SLinus Torvalds 31304ac91378SJan Blunck new_dir = newnd.path.dentry; 31311da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31321da177e4SLinus Torvalds goto exit2; 31331da177e4SLinus Torvalds 31340612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31350612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31364e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31370612d9fbSOGAWA Hirofumi 31381da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31391da177e4SLinus Torvalds 314049705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31411da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31421da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31431da177e4SLinus Torvalds goto exit3; 31441da177e4SLinus Torvalds /* source must exist */ 31451da177e4SLinus Torvalds error = -ENOENT; 31461da177e4SLinus Torvalds if (!old_dentry->d_inode) 31471da177e4SLinus Torvalds goto exit4; 31481da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31491da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31501da177e4SLinus Torvalds error = -ENOTDIR; 31511da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31521da177e4SLinus Torvalds goto exit4; 31531da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31541da177e4SLinus Torvalds goto exit4; 31551da177e4SLinus Torvalds } 31561da177e4SLinus Torvalds /* source should not be ancestor of target */ 31571da177e4SLinus Torvalds error = -EINVAL; 31581da177e4SLinus Torvalds if (old_dentry == trap) 31591da177e4SLinus Torvalds goto exit4; 316049705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31611da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31621da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31631da177e4SLinus Torvalds goto exit4; 31641da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31651da177e4SLinus Torvalds error = -ENOTEMPTY; 31661da177e4SLinus Torvalds if (new_dentry == trap) 31671da177e4SLinus Torvalds goto exit5; 31681da177e4SLinus Torvalds 31699079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 31709079b1ebSDave Hansen if (error) 31719079b1ebSDave Hansen goto exit5; 3172be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3173be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3174be6d3e56SKentaro Takeda if (error) 3175be6d3e56SKentaro Takeda goto exit6; 31761da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 31771da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3178be6d3e56SKentaro Takeda exit6: 31799079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 31801da177e4SLinus Torvalds exit5: 31811da177e4SLinus Torvalds dput(new_dentry); 31821da177e4SLinus Torvalds exit4: 31831da177e4SLinus Torvalds dput(old_dentry); 31841da177e4SLinus Torvalds exit3: 31851da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 31861da177e4SLinus Torvalds exit2: 31871d957f9bSJan Blunck path_put(&newnd.path); 31882ad94ae6SAl Viro putname(to); 31891da177e4SLinus Torvalds exit1: 31901d957f9bSJan Blunck path_put(&oldnd.path); 31911da177e4SLinus Torvalds putname(from); 31922ad94ae6SAl Viro exit: 31931da177e4SLinus Torvalds return error; 31941da177e4SLinus Torvalds } 31951da177e4SLinus Torvalds 3196a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 31975590ff0dSUlrich Drepper { 31985590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 31995590ff0dSUlrich Drepper } 32005590ff0dSUlrich Drepper 32011da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32021da177e4SLinus Torvalds { 32031da177e4SLinus Torvalds int len; 32041da177e4SLinus Torvalds 32051da177e4SLinus Torvalds len = PTR_ERR(link); 32061da177e4SLinus Torvalds if (IS_ERR(link)) 32071da177e4SLinus Torvalds goto out; 32081da177e4SLinus Torvalds 32091da177e4SLinus Torvalds len = strlen(link); 32101da177e4SLinus Torvalds if (len > (unsigned) buflen) 32111da177e4SLinus Torvalds len = buflen; 32121da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32131da177e4SLinus Torvalds len = -EFAULT; 32141da177e4SLinus Torvalds out: 32151da177e4SLinus Torvalds return len; 32161da177e4SLinus Torvalds } 32171da177e4SLinus Torvalds 32181da177e4SLinus Torvalds /* 32191da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32201da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32211da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32221da177e4SLinus Torvalds */ 32231da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32241da177e4SLinus Torvalds { 32251da177e4SLinus Torvalds struct nameidata nd; 3226cc314eefSLinus Torvalds void *cookie; 3227694a1764SMarcin Slusarz int res; 3228cc314eefSLinus Torvalds 32291da177e4SLinus Torvalds nd.depth = 0; 3230cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3231694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3232694a1764SMarcin Slusarz return PTR_ERR(cookie); 3233694a1764SMarcin Slusarz 3234694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32351da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3236cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3237694a1764SMarcin Slusarz return res; 32381da177e4SLinus Torvalds } 32391da177e4SLinus Torvalds 32401da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32411da177e4SLinus Torvalds { 32421da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32431da177e4SLinus Torvalds } 32441da177e4SLinus Torvalds 32451da177e4SLinus Torvalds /* get the link contents into pagecache */ 32461da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32471da177e4SLinus Torvalds { 3248ebd09abbSDuane Griffin char *kaddr; 32491da177e4SLinus Torvalds struct page *page; 32501da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3251090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32521da177e4SLinus Torvalds if (IS_ERR(page)) 32536fe6900eSNick Piggin return (char*)page; 32541da177e4SLinus Torvalds *ppage = page; 3255ebd09abbSDuane Griffin kaddr = kmap(page); 3256ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3257ebd09abbSDuane Griffin return kaddr; 32581da177e4SLinus Torvalds } 32591da177e4SLinus Torvalds 32601da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32611da177e4SLinus Torvalds { 32621da177e4SLinus Torvalds struct page *page = NULL; 32631da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32641da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32651da177e4SLinus Torvalds if (page) { 32661da177e4SLinus Torvalds kunmap(page); 32671da177e4SLinus Torvalds page_cache_release(page); 32681da177e4SLinus Torvalds } 32691da177e4SLinus Torvalds return res; 32701da177e4SLinus Torvalds } 32711da177e4SLinus Torvalds 3272cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 32731da177e4SLinus Torvalds { 3274cc314eefSLinus Torvalds struct page *page = NULL; 32751da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3276cc314eefSLinus Torvalds return page; 32771da177e4SLinus Torvalds } 32781da177e4SLinus Torvalds 3279cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 32801da177e4SLinus Torvalds { 3281cc314eefSLinus Torvalds struct page *page = cookie; 3282cc314eefSLinus Torvalds 3283cc314eefSLinus Torvalds if (page) { 32841da177e4SLinus Torvalds kunmap(page); 32851da177e4SLinus Torvalds page_cache_release(page); 32861da177e4SLinus Torvalds } 32871da177e4SLinus Torvalds } 32881da177e4SLinus Torvalds 328954566b2cSNick Piggin /* 329054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 329154566b2cSNick Piggin */ 329254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 32931da177e4SLinus Torvalds { 32941da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 32950adb25d2SKirill Korotaev struct page *page; 3296afddba49SNick Piggin void *fsdata; 3297beb497abSDmitriy Monakhov int err; 32981da177e4SLinus Torvalds char *kaddr; 329954566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 330054566b2cSNick Piggin if (nofs) 330154566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33021da177e4SLinus Torvalds 33037e53cac4SNeilBrown retry: 3304afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 330554566b2cSNick Piggin flags, &page, &fsdata); 33061da177e4SLinus Torvalds if (err) 3307afddba49SNick Piggin goto fail; 3308afddba49SNick Piggin 33091da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33101da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33111da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3312afddba49SNick Piggin 3313afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3314afddba49SNick Piggin page, fsdata); 33151da177e4SLinus Torvalds if (err < 0) 33161da177e4SLinus Torvalds goto fail; 3317afddba49SNick Piggin if (err < len-1) 3318afddba49SNick Piggin goto retry; 3319afddba49SNick Piggin 33201da177e4SLinus Torvalds mark_inode_dirty(inode); 33211da177e4SLinus Torvalds return 0; 33221da177e4SLinus Torvalds fail: 33231da177e4SLinus Torvalds return err; 33241da177e4SLinus Torvalds } 33251da177e4SLinus Torvalds 33260adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33270adb25d2SKirill Korotaev { 33280adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 332954566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33300adb25d2SKirill Korotaev } 33310adb25d2SKirill Korotaev 333292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33331da177e4SLinus Torvalds .readlink = generic_readlink, 33341da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33351da177e4SLinus Torvalds .put_link = page_put_link, 33361da177e4SLinus Torvalds }; 33371da177e4SLinus Torvalds 33382d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3339cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33401da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33411da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33421da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33431da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33441da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33451da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33461da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33471da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33481da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33490adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33501da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33511da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3352c9c6cac0SAl Viro EXPORT_SYMBOL(kern_path_parent); 3353d1811465SAl Viro EXPORT_SYMBOL(kern_path); 335416f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3355f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33568c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 33571da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33581da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33591da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33601da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33611da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33621da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33631da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33641da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33651da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33661da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33671da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33681da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33691da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 33701da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3371