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 45890dbb77bSNick Piggin /* 45990dbb77bSNick Piggin * It can be possible to revalidate the dentry that we started 46090dbb77bSNick Piggin * the path walk with. force_reval_path may also revalidate the 46190dbb77bSNick Piggin * dentry already committed to the nameidata. 46290dbb77bSNick Piggin */ 46390dbb77bSNick Piggin if (unlikely(parent == dentry)) 46490dbb77bSNick Piggin return nameidata_drop_rcu(nd); 46590dbb77bSNick Piggin 46631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 46731e6b01fSNick Piggin if (nd->root.mnt) { 46831e6b01fSNick Piggin spin_lock(&fs->lock); 46931e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 47031e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 47131e6b01fSNick Piggin goto err_root; 47231e6b01fSNick Piggin } 47331e6b01fSNick Piggin spin_lock(&parent->d_lock); 47431e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 47531e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 47631e6b01fSNick Piggin goto err; 47731e6b01fSNick Piggin /* 47831e6b01fSNick Piggin * If the sequence check on the child dentry passed, then the child has 47931e6b01fSNick Piggin * not been removed from its parent. This means the parent dentry must 48031e6b01fSNick Piggin * be valid and able to take a reference at this point. 48131e6b01fSNick Piggin */ 48231e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 48331e6b01fSNick Piggin BUG_ON(!parent->d_count); 48431e6b01fSNick Piggin parent->d_count++; 48531e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 48631e6b01fSNick Piggin spin_unlock(&parent->d_lock); 48731e6b01fSNick Piggin if (nd->root.mnt) { 48831e6b01fSNick Piggin path_get(&nd->root); 48931e6b01fSNick Piggin spin_unlock(&fs->lock); 49031e6b01fSNick Piggin } 49131e6b01fSNick Piggin mntget(nd->path.mnt); 49231e6b01fSNick Piggin 49331e6b01fSNick Piggin rcu_read_unlock(); 49431e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 49531e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 49631e6b01fSNick Piggin return 0; 49731e6b01fSNick Piggin err: 49831e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 49931e6b01fSNick Piggin spin_unlock(&parent->d_lock); 50031e6b01fSNick Piggin err_root: 50131e6b01fSNick Piggin if (nd->root.mnt) 50231e6b01fSNick Piggin spin_unlock(&fs->lock); 50331e6b01fSNick Piggin return -ECHILD; 50431e6b01fSNick Piggin } 50531e6b01fSNick Piggin 50631e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 50731e6b01fSNick Piggin static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry) 50831e6b01fSNick Piggin { 50931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) 51031e6b01fSNick Piggin return nameidata_dentry_drop_rcu(nd, dentry); 51131e6b01fSNick Piggin return 0; 51231e6b01fSNick Piggin } 51331e6b01fSNick Piggin 51431e6b01fSNick Piggin /** 51531e6b01fSNick Piggin * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk 51631e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 51739191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 51831e6b01fSNick Piggin * 51931e6b01fSNick Piggin * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. 52031e6b01fSNick Piggin * nd->path should be the final element of the lookup, so nd->root is discarded. 52131e6b01fSNick Piggin * Must be called from rcu-walk context. 52231e6b01fSNick Piggin */ 52331e6b01fSNick Piggin static int nameidata_drop_rcu_last(struct nameidata *nd) 52431e6b01fSNick Piggin { 52531e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 52631e6b01fSNick Piggin 52731e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 52831e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 52931e6b01fSNick Piggin nd->root.mnt = NULL; 53031e6b01fSNick Piggin spin_lock(&dentry->d_lock); 53131e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 53231e6b01fSNick Piggin goto err_unlock; 53331e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 53431e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 53531e6b01fSNick Piggin 53631e6b01fSNick Piggin mntget(nd->path.mnt); 53731e6b01fSNick Piggin 53831e6b01fSNick Piggin rcu_read_unlock(); 53931e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 54031e6b01fSNick Piggin 54131e6b01fSNick Piggin return 0; 54231e6b01fSNick Piggin 54331e6b01fSNick Piggin err_unlock: 54431e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 54531e6b01fSNick Piggin rcu_read_unlock(); 54631e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 54731e6b01fSNick Piggin return -ECHILD; 54831e6b01fSNick Piggin } 54931e6b01fSNick Piggin 55031e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 55131e6b01fSNick Piggin static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd) 55231e6b01fSNick Piggin { 55331e6b01fSNick Piggin if (likely(nd->flags & LOOKUP_RCU)) 55431e6b01fSNick Piggin return nameidata_drop_rcu_last(nd); 55531e6b01fSNick Piggin return 0; 55631e6b01fSNick Piggin } 55731e6b01fSNick Piggin 55831e6b01fSNick Piggin /** 559834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 560834f2a4aSTrond Myklebust * @nd: pointer to nameidata 561834f2a4aSTrond Myklebust */ 562834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 563834f2a4aSTrond Myklebust { 5642dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 5652dab5974SLinus Torvalds 5662dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 5672dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 5682dab5974SLinus Torvalds put_filp(file); 569834f2a4aSTrond Myklebust else 5702dab5974SLinus Torvalds fput(file); 5712dab5974SLinus Torvalds } 572834f2a4aSTrond Myklebust } 573834f2a4aSTrond Myklebust 574bb20c18dSNick Piggin /* 575bb20c18dSNick Piggin * Call d_revalidate and handle filesystems that request rcu-walk 576bb20c18dSNick Piggin * to be dropped. This may be called and return in rcu-walk mode, 577bb20c18dSNick Piggin * regardless of success or error. If -ECHILD is returned, the caller 578bb20c18dSNick Piggin * must return -ECHILD back up the path walk stack so path walk may 579bb20c18dSNick Piggin * be restarted in ref-walk mode. 580bb20c18dSNick Piggin */ 58134286d66SNick Piggin static int d_revalidate(struct dentry *dentry, struct nameidata *nd) 58234286d66SNick Piggin { 58334286d66SNick Piggin int status; 58434286d66SNick Piggin 58534286d66SNick Piggin status = dentry->d_op->d_revalidate(dentry, nd); 58634286d66SNick Piggin if (status == -ECHILD) { 58734286d66SNick Piggin if (nameidata_dentry_drop_rcu(nd, dentry)) 58834286d66SNick Piggin return status; 58934286d66SNick Piggin status = dentry->d_op->d_revalidate(dentry, nd); 59034286d66SNick Piggin } 59134286d66SNick Piggin 59234286d66SNick Piggin return status; 59334286d66SNick Piggin } 59434286d66SNick Piggin 595f5e1c1c1SAl Viro static struct dentry * 596bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 597bcdc5e01SIan Kent { 598f5e1c1c1SAl Viro int status = d_revalidate(dentry, nd); 599bcdc5e01SIan Kent if (unlikely(status <= 0)) { 600bcdc5e01SIan Kent /* 601bcdc5e01SIan Kent * The dentry failed validation. 602bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 603bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 604bcdc5e01SIan Kent * to return a fail status. 605bcdc5e01SIan Kent */ 60634286d66SNick Piggin if (status < 0) { 60734286d66SNick Piggin dput(dentry); 60834286d66SNick Piggin dentry = ERR_PTR(status); 609f5e1c1c1SAl Viro } else if (!d_invalidate(dentry)) { 610bcdc5e01SIan Kent dput(dentry); 611bcdc5e01SIan Kent dentry = NULL; 612bcdc5e01SIan Kent } 613bcdc5e01SIan Kent } 614f5e1c1c1SAl Viro return dentry; 615f5e1c1c1SAl Viro } 616f5e1c1c1SAl Viro 617f5e1c1c1SAl Viro static inline struct dentry * 618f5e1c1c1SAl Viro do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd) 619f5e1c1c1SAl Viro { 620f5e1c1c1SAl Viro int status = dentry->d_op->d_revalidate(dentry, nd); 621f5e1c1c1SAl Viro if (likely(status > 0)) 622f5e1c1c1SAl Viro return dentry; 623f5e1c1c1SAl Viro if (status == -ECHILD) { 624f5e1c1c1SAl Viro if (nameidata_dentry_drop_rcu(nd, dentry)) 625f5e1c1c1SAl Viro return ERR_PTR(-ECHILD); 626f5e1c1c1SAl Viro return do_revalidate(dentry, nd); 627f5e1c1c1SAl Viro } 628f5e1c1c1SAl Viro if (status < 0) 629f5e1c1c1SAl Viro return ERR_PTR(status); 630f5e1c1c1SAl Viro /* Don't d_invalidate in rcu-walk mode */ 631f5e1c1c1SAl Viro if (nameidata_dentry_drop_rcu(nd, dentry)) 632f5e1c1c1SAl Viro return ERR_PTR(-ECHILD); 633f5e1c1c1SAl Viro if (!d_invalidate(dentry)) { 634f5e1c1c1SAl Viro dput(dentry); 635f5e1c1c1SAl Viro dentry = NULL; 636bcdc5e01SIan Kent } 637bcdc5e01SIan Kent return dentry; 638bcdc5e01SIan Kent } 639bcdc5e01SIan Kent 640fb045adbSNick Piggin static inline int need_reval_dot(struct dentry *dentry) 641fb045adbSNick Piggin { 642fb045adbSNick Piggin if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 643fb045adbSNick Piggin return 0; 644fb045adbSNick Piggin 645fb045adbSNick Piggin if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 646fb045adbSNick Piggin return 0; 647fb045adbSNick Piggin 648fb045adbSNick Piggin return 1; 649fb045adbSNick Piggin } 650fb045adbSNick Piggin 6511da177e4SLinus Torvalds /* 65239159de2SJeff Layton * force_reval_path - force revalidation of a dentry 65339159de2SJeff Layton * 65439159de2SJeff Layton * In some situations the path walking code will trust dentries without 65539159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 65639159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 65739159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 65839159de2SJeff Layton * a d_revalidate call before proceeding. 65939159de2SJeff Layton * 66039159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 66139159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 66239159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 66339159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 66439159de2SJeff Layton * to the path if necessary. 66539159de2SJeff Layton */ 66639159de2SJeff Layton static int 66739159de2SJeff Layton force_reval_path(struct path *path, struct nameidata *nd) 66839159de2SJeff Layton { 66939159de2SJeff Layton int status; 67039159de2SJeff Layton struct dentry *dentry = path->dentry; 67139159de2SJeff Layton 67239159de2SJeff Layton /* 67339159de2SJeff Layton * only check on filesystems where it's possible for the dentry to 674fb045adbSNick Piggin * become stale. 67539159de2SJeff Layton */ 676fb045adbSNick Piggin if (!need_reval_dot(dentry)) 67739159de2SJeff Layton return 0; 67839159de2SJeff Layton 67934286d66SNick Piggin status = d_revalidate(dentry, nd); 68039159de2SJeff Layton if (status > 0) 68139159de2SJeff Layton return 0; 68239159de2SJeff Layton 68339159de2SJeff Layton if (!status) { 68439159de2SJeff Layton d_invalidate(dentry); 68539159de2SJeff Layton status = -ESTALE; 68639159de2SJeff Layton } 68739159de2SJeff Layton return status; 68839159de2SJeff Layton } 68939159de2SJeff Layton 69039159de2SJeff Layton /* 691b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 692b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 693b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 6941da177e4SLinus Torvalds * 6951da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 696b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 6971da177e4SLinus Torvalds * complete permission check. 6981da177e4SLinus Torvalds */ 699b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 7001da177e4SLinus Torvalds { 7015909ccaaSLinus Torvalds int ret; 7021da177e4SLinus Torvalds 703cb9179eaSLinus Torvalds if (inode->i_op->permission) { 704b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 705b74c79e9SNick Piggin } else { 706b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 707b74c79e9SNick Piggin inode->i_op->check_acl); 708cb9179eaSLinus Torvalds } 709b74c79e9SNick Piggin if (likely(!ret)) 7101da177e4SLinus Torvalds goto ok; 711b74c79e9SNick Piggin if (ret == -ECHILD) 71231e6b01fSNick Piggin return ret; 7131da177e4SLinus Torvalds 714f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 7151da177e4SLinus Torvalds goto ok; 7161da177e4SLinus Torvalds 7175909ccaaSLinus Torvalds return ret; 7181da177e4SLinus Torvalds ok: 719b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 7201da177e4SLinus Torvalds } 7211da177e4SLinus Torvalds 7222a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7232a737871SAl Viro { 724f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 725f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7262a737871SAl Viro } 7272a737871SAl Viro 7286de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 7296de88d72SAl Viro 73031e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 73131e6b01fSNick Piggin { 73231e6b01fSNick Piggin if (!nd->root.mnt) { 73331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 734c28cc364SNick Piggin unsigned seq; 735c28cc364SNick Piggin 736c28cc364SNick Piggin do { 737c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 73831e6b01fSNick Piggin nd->root = fs->root; 739c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 74031e6b01fSNick Piggin } 74131e6b01fSNick Piggin } 74231e6b01fSNick Piggin 743f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 7441da177e4SLinus Torvalds { 74531e6b01fSNick Piggin int ret; 74631e6b01fSNick Piggin 7471da177e4SLinus Torvalds if (IS_ERR(link)) 7481da177e4SLinus Torvalds goto fail; 7491da177e4SLinus Torvalds 7501da177e4SLinus Torvalds if (*link == '/') { 7512a737871SAl Viro set_root(nd); 7521d957f9bSJan Blunck path_put(&nd->path); 7532a737871SAl Viro nd->path = nd->root; 7542a737871SAl Viro path_get(&nd->root); 7551da177e4SLinus Torvalds } 75631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 757b4091d5fSChristoph Hellwig 75831e6b01fSNick Piggin ret = link_path_walk(link, nd); 75931e6b01fSNick Piggin return ret; 7601da177e4SLinus Torvalds fail: 7611d957f9bSJan Blunck path_put(&nd->path); 7621da177e4SLinus Torvalds return PTR_ERR(link); 7631da177e4SLinus Torvalds } 7641da177e4SLinus Torvalds 7651d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 766051d3812SIan Kent { 767051d3812SIan Kent dput(path->dentry); 7684ac91378SJan Blunck if (path->mnt != nd->path.mnt) 769051d3812SIan Kent mntput(path->mnt); 770051d3812SIan Kent } 771051d3812SIan Kent 7727b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7737b9337aaSNick Piggin struct nameidata *nd) 774051d3812SIan Kent { 77531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7764ac91378SJan Blunck dput(nd->path.dentry); 77731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7784ac91378SJan Blunck mntput(nd->path.mnt); 7799a229683SHuang Shijie } 78031e6b01fSNick Piggin nd->path.mnt = path->mnt; 7814ac91378SJan Blunck nd->path.dentry = path->dentry; 782051d3812SIan Kent } 783051d3812SIan Kent 784def4af30SAl Viro static __always_inline int 7857b9337aaSNick Piggin __do_follow_link(const struct path *link, struct nameidata *nd, void **p) 7861da177e4SLinus Torvalds { 7871da177e4SLinus Torvalds int error; 7887b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7891da177e4SLinus Torvalds 790844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 791844a3917SAl Viro 7927b9337aaSNick Piggin touch_atime(link->mnt, dentry); 7931da177e4SLinus Torvalds nd_set_link(nd, NULL); 794cd4e91d3SAl Viro 79587556ef1SDavid Howells if (link->mnt == nd->path.mnt) 7967b9337aaSNick Piggin mntget(link->mnt); 79731e6b01fSNick Piggin 79886acdca1SAl Viro nd->last_type = LAST_BIND; 799def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 800def4af30SAl Viro error = PTR_ERR(*p); 801def4af30SAl Viro if (!IS_ERR(*p)) { 8021da177e4SLinus Torvalds char *s = nd_get_link(nd); 803cc314eefSLinus Torvalds error = 0; 8041da177e4SLinus Torvalds if (s) 8051da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 80639159de2SJeff Layton else if (nd->last_type == LAST_BIND) { 80739159de2SJeff Layton error = force_reval_path(&nd->path, nd); 80839159de2SJeff Layton if (error) 80939159de2SJeff Layton path_put(&nd->path); 81039159de2SJeff Layton } 8111da177e4SLinus Torvalds } 8121da177e4SLinus Torvalds return error; 8131da177e4SLinus Torvalds } 8141da177e4SLinus Torvalds 8151da177e4SLinus Torvalds /* 8161da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 8171da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 8181da177e4SLinus Torvalds * 8191da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 8201da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 8211da177e4SLinus Torvalds */ 82290ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 8231da177e4SLinus Torvalds { 824def4af30SAl Viro void *cookie; 8251da177e4SLinus Torvalds int err = -ELOOP; 826844a3917SAl Viro 827844a3917SAl Viro /* We drop rcu-walk here */ 828844a3917SAl Viro if (nameidata_dentry_drop_rcu_maybe(nd, path->dentry)) 829844a3917SAl Viro return -ECHILD; 830844a3917SAl Viro 8311da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 8321da177e4SLinus Torvalds goto loop; 8331da177e4SLinus Torvalds if (current->total_link_count >= 40) 8341da177e4SLinus Torvalds goto loop; 8351da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 8361da177e4SLinus Torvalds cond_resched(); 83790ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 8381da177e4SLinus Torvalds if (err) 8391da177e4SLinus Torvalds goto loop; 8401da177e4SLinus Torvalds current->link_count++; 8411da177e4SLinus Torvalds current->total_link_count++; 8421da177e4SLinus Torvalds nd->depth++; 843def4af30SAl Viro err = __do_follow_link(path, nd, &cookie); 844def4af30SAl Viro if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link) 845def4af30SAl Viro path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie); 846258fa999SAl Viro path_put(path); 8471da177e4SLinus Torvalds current->link_count--; 8481da177e4SLinus Torvalds nd->depth--; 8491da177e4SLinus Torvalds return err; 8501da177e4SLinus Torvalds loop: 8511d957f9bSJan Blunck path_put_conditional(path, nd); 8521d957f9bSJan Blunck path_put(&nd->path); 8531da177e4SLinus Torvalds return err; 8541da177e4SLinus Torvalds } 8551da177e4SLinus Torvalds 85631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 85731e6b01fSNick Piggin { 85831e6b01fSNick Piggin struct vfsmount *parent; 85931e6b01fSNick Piggin struct dentry *mountpoint; 86031e6b01fSNick Piggin 86131e6b01fSNick Piggin parent = path->mnt->mnt_parent; 86231e6b01fSNick Piggin if (parent == path->mnt) 86331e6b01fSNick Piggin return 0; 86431e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 86531e6b01fSNick Piggin path->dentry = mountpoint; 86631e6b01fSNick Piggin path->mnt = parent; 86731e6b01fSNick Piggin return 1; 86831e6b01fSNick Piggin } 86931e6b01fSNick Piggin 870bab77ebfSAl Viro int follow_up(struct path *path) 8711da177e4SLinus Torvalds { 8721da177e4SLinus Torvalds struct vfsmount *parent; 8731da177e4SLinus Torvalds struct dentry *mountpoint; 87499b7db7bSNick Piggin 87599b7db7bSNick Piggin br_read_lock(vfsmount_lock); 876bab77ebfSAl Viro parent = path->mnt->mnt_parent; 877bab77ebfSAl Viro if (parent == path->mnt) { 87899b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 8791da177e4SLinus Torvalds return 0; 8801da177e4SLinus Torvalds } 8811da177e4SLinus Torvalds mntget(parent); 882bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 88399b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 884bab77ebfSAl Viro dput(path->dentry); 885bab77ebfSAl Viro path->dentry = mountpoint; 886bab77ebfSAl Viro mntput(path->mnt); 887bab77ebfSAl Viro path->mnt = parent; 8881da177e4SLinus Torvalds return 1; 8891da177e4SLinus Torvalds } 8901da177e4SLinus Torvalds 891b5c84bf6SNick Piggin /* 8929875cf80SDavid Howells * Perform an automount 8939875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 8949875cf80SDavid Howells * were called with. 8951da177e4SLinus Torvalds */ 8969875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 8979875cf80SDavid Howells bool *need_mntput) 89831e6b01fSNick Piggin { 8999875cf80SDavid Howells struct vfsmount *mnt; 900ea5b778aSDavid Howells int err; 9019875cf80SDavid Howells 9029875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9039875cf80SDavid Howells return -EREMOTE; 9049875cf80SDavid Howells 9056f45b656SDavid Howells /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT 9066f45b656SDavid Howells * and this is the terminal part of the path. 9076f45b656SDavid Howells */ 9086f45b656SDavid Howells if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_CONTINUE)) 9096f45b656SDavid Howells return -EISDIR; /* we actually want to stop here */ 9106f45b656SDavid Howells 9119875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 9129875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 9139875cf80SDavid Howells * or wants to open the mounted directory. 9149875cf80SDavid Howells * 9159875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 9169875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 9179875cf80SDavid Howells * appended a '/' to the name. 9189875cf80SDavid Howells */ 9199875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 9209875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 9219875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 9229875cf80SDavid Howells return -EISDIR; 9239875cf80SDavid Howells 9249875cf80SDavid Howells current->total_link_count++; 9259875cf80SDavid Howells if (current->total_link_count >= 40) 9269875cf80SDavid Howells return -ELOOP; 9279875cf80SDavid Howells 9289875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9299875cf80SDavid Howells if (IS_ERR(mnt)) { 9309875cf80SDavid Howells /* 9319875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9329875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9339875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9349875cf80SDavid Howells * 9359875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9369875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9379875cf80SDavid Howells * the path is inaccessible and we should say so. 9389875cf80SDavid Howells */ 9399875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 9409875cf80SDavid Howells return -EREMOTE; 9419875cf80SDavid Howells return PTR_ERR(mnt); 94231e6b01fSNick Piggin } 943ea5b778aSDavid Howells 9449875cf80SDavid Howells if (!mnt) /* mount collision */ 9459875cf80SDavid Howells return 0; 9469875cf80SDavid Howells 94719a167afSAl Viro err = finish_automount(mnt, path); 948ea5b778aSDavid Howells 949ea5b778aSDavid Howells switch (err) { 950ea5b778aSDavid Howells case -EBUSY: 951ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 95219a167afSAl Viro return 0; 953ea5b778aSDavid Howells case 0: 954463ffb2eSAl Viro dput(path->dentry); 9559875cf80SDavid Howells if (*need_mntput) 9569875cf80SDavid Howells mntput(path->mnt); 9579875cf80SDavid Howells path->mnt = mnt; 9589875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9599875cf80SDavid Howells *need_mntput = true; 9609875cf80SDavid Howells return 0; 96119a167afSAl Viro default: 96219a167afSAl Viro return err; 9639875cf80SDavid Howells } 96419a167afSAl Viro 965ea5b778aSDavid Howells } 9669875cf80SDavid Howells 9679875cf80SDavid Howells /* 9689875cf80SDavid Howells * Handle a dentry that is managed in some way. 969cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9709875cf80SDavid Howells * - Flagged as mountpoint 9719875cf80SDavid Howells * - Flagged as automount point 9729875cf80SDavid Howells * 9739875cf80SDavid Howells * This may only be called in refwalk mode. 9749875cf80SDavid Howells * 9759875cf80SDavid Howells * Serialization is taken care of in namespace.c 9769875cf80SDavid Howells */ 9779875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9789875cf80SDavid Howells { 9799875cf80SDavid Howells unsigned managed; 9809875cf80SDavid Howells bool need_mntput = false; 9819875cf80SDavid Howells int ret; 9829875cf80SDavid Howells 9839875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9849875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9859875cf80SDavid Howells * the components of that value change under us */ 9869875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9879875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9889875cf80SDavid Howells unlikely(managed != 0)) { 989cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 990cc53ce53SDavid Howells * being held. */ 991cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 992cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 993cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 994ab90911fSDavid Howells ret = path->dentry->d_op->d_manage(path->dentry, 995ab90911fSDavid Howells false, false); 996cc53ce53SDavid Howells if (ret < 0) 997cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 998cc53ce53SDavid Howells } 999cc53ce53SDavid Howells 10009875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10019875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10029875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10039875cf80SDavid Howells if (mounted) { 10049875cf80SDavid Howells dput(path->dentry); 10059875cf80SDavid Howells if (need_mntput) 1006463ffb2eSAl Viro mntput(path->mnt); 1007463ffb2eSAl Viro path->mnt = mounted; 1008463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10099875cf80SDavid Howells need_mntput = true; 10109875cf80SDavid Howells continue; 1011463ffb2eSAl Viro } 1012463ffb2eSAl Viro 10139875cf80SDavid Howells /* Something is mounted on this dentry in another 10149875cf80SDavid Howells * namespace and/or whatever was mounted there in this 10159875cf80SDavid Howells * namespace got unmounted before we managed to get the 10169875cf80SDavid Howells * vfsmount_lock */ 10171da177e4SLinus Torvalds } 10189875cf80SDavid Howells 10199875cf80SDavid Howells /* Handle an automount point */ 10209875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10219875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10229875cf80SDavid Howells if (ret < 0) 10239875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 10249875cf80SDavid Howells continue; 10259875cf80SDavid Howells } 10269875cf80SDavid Howells 10279875cf80SDavid Howells /* We didn't change the current path point */ 10289875cf80SDavid Howells break; 10299875cf80SDavid Howells } 10309875cf80SDavid Howells return 0; 10311da177e4SLinus Torvalds } 10321da177e4SLinus Torvalds 1033cc53ce53SDavid Howells int follow_down_one(struct path *path) 10341da177e4SLinus Torvalds { 10351da177e4SLinus Torvalds struct vfsmount *mounted; 10361da177e4SLinus Torvalds 10371c755af4SAl Viro mounted = lookup_mnt(path); 10381da177e4SLinus Torvalds if (mounted) { 10399393bd07SAl Viro dput(path->dentry); 10409393bd07SAl Viro mntput(path->mnt); 10419393bd07SAl Viro path->mnt = mounted; 10429393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10431da177e4SLinus Torvalds return 1; 10441da177e4SLinus Torvalds } 10451da177e4SLinus Torvalds return 0; 10461da177e4SLinus Torvalds } 10471da177e4SLinus Torvalds 10489875cf80SDavid Howells /* 10499875cf80SDavid Howells * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we 1050cc53ce53SDavid Howells * meet a managed dentry and we're not walking to "..". True is returned to 10519875cf80SDavid Howells * continue, false to abort. 10529875cf80SDavid Howells */ 10539875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 10549875cf80SDavid Howells struct inode **inode, bool reverse_transit) 10559875cf80SDavid Howells { 10569875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10579875cf80SDavid Howells struct vfsmount *mounted; 1058ab90911fSDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) && 1059ab90911fSDavid Howells !reverse_transit && 1060ab90911fSDavid Howells path->dentry->d_op->d_manage(path->dentry, false, true) < 0) 1061ab90911fSDavid Howells return false; 10629875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 10639875cf80SDavid Howells if (!mounted) 10649875cf80SDavid Howells break; 10659875cf80SDavid Howells path->mnt = mounted; 10669875cf80SDavid Howells path->dentry = mounted->mnt_root; 10679875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 10689875cf80SDavid Howells *inode = path->dentry->d_inode; 10699875cf80SDavid Howells } 10709875cf80SDavid Howells 10719875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 10729875cf80SDavid Howells return reverse_transit; 10739875cf80SDavid Howells return true; 10749875cf80SDavid Howells } 10759875cf80SDavid Howells 107631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 107731e6b01fSNick Piggin { 107831e6b01fSNick Piggin struct inode *inode = nd->inode; 107931e6b01fSNick Piggin 108031e6b01fSNick Piggin set_root_rcu(nd); 108131e6b01fSNick Piggin 108231e6b01fSNick Piggin while (1) { 108331e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 108431e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 108531e6b01fSNick Piggin break; 108631e6b01fSNick Piggin } 108731e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 108831e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 108931e6b01fSNick Piggin struct dentry *parent = old->d_parent; 109031e6b01fSNick Piggin unsigned seq; 109131e6b01fSNick Piggin 109231e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 109331e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 109431e6b01fSNick Piggin return -ECHILD; 109531e6b01fSNick Piggin inode = parent->d_inode; 109631e6b01fSNick Piggin nd->path.dentry = parent; 109731e6b01fSNick Piggin nd->seq = seq; 109831e6b01fSNick Piggin break; 109931e6b01fSNick Piggin } 110031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 110131e6b01fSNick Piggin break; 110231e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 110331e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 110431e6b01fSNick Piggin } 11059875cf80SDavid Howells __follow_mount_rcu(nd, &nd->path, &inode, true); 110631e6b01fSNick Piggin nd->inode = inode; 110731e6b01fSNick Piggin 110831e6b01fSNick Piggin return 0; 110931e6b01fSNick Piggin } 111031e6b01fSNick Piggin 11119875cf80SDavid Howells /* 1112cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1113cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1114cc53ce53SDavid Howells * caller is permitted to proceed or not. 1115cc53ce53SDavid Howells * 1116cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1117cc53ce53SDavid Howells * being true). 1118cc53ce53SDavid Howells */ 1119cc53ce53SDavid Howells int follow_down(struct path *path, bool mounting_here) 1120cc53ce53SDavid Howells { 1121cc53ce53SDavid Howells unsigned managed; 1122cc53ce53SDavid Howells int ret; 1123cc53ce53SDavid Howells 1124cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1125cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1126cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1127cc53ce53SDavid Howells * being held. 1128cc53ce53SDavid Howells * 1129cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1130cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1131cc53ce53SDavid Howells * other than its daemon the right to mount on its 1132cc53ce53SDavid Howells * superstructure. 1133cc53ce53SDavid Howells * 1134cc53ce53SDavid Howells * The filesystem may sleep at this point. 1135cc53ce53SDavid Howells */ 1136cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1137cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1138cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1139ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 1140ab90911fSDavid Howells path->dentry, mounting_here, false); 1141cc53ce53SDavid Howells if (ret < 0) 1142cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1143cc53ce53SDavid Howells } 1144cc53ce53SDavid Howells 1145cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1146cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1147cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1148cc53ce53SDavid Howells if (!mounted) 1149cc53ce53SDavid Howells break; 1150cc53ce53SDavid Howells dput(path->dentry); 1151cc53ce53SDavid Howells mntput(path->mnt); 1152cc53ce53SDavid Howells path->mnt = mounted; 1153cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1154cc53ce53SDavid Howells continue; 1155cc53ce53SDavid Howells } 1156cc53ce53SDavid Howells 1157cc53ce53SDavid Howells /* Don't handle automount points here */ 1158cc53ce53SDavid Howells break; 1159cc53ce53SDavid Howells } 1160cc53ce53SDavid Howells return 0; 1161cc53ce53SDavid Howells } 1162cc53ce53SDavid Howells 1163cc53ce53SDavid Howells /* 11649875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 11659875cf80SDavid Howells */ 11669875cf80SDavid Howells static void follow_mount(struct path *path) 11679875cf80SDavid Howells { 11689875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11699875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11709875cf80SDavid Howells if (!mounted) 11719875cf80SDavid Howells break; 11729875cf80SDavid Howells dput(path->dentry); 11739875cf80SDavid Howells mntput(path->mnt); 11749875cf80SDavid Howells path->mnt = mounted; 11759875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11769875cf80SDavid Howells } 11779875cf80SDavid Howells } 11789875cf80SDavid Howells 117931e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11801da177e4SLinus Torvalds { 11812a737871SAl Viro set_root(nd); 1182e518ddb7SAndreas Mohr 11831da177e4SLinus Torvalds while(1) { 11844ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11851da177e4SLinus Torvalds 11862a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11872a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11881da177e4SLinus Torvalds break; 11891da177e4SLinus Torvalds } 11904ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11913088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11923088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11931da177e4SLinus Torvalds dput(old); 11941da177e4SLinus Torvalds break; 11951da177e4SLinus Torvalds } 11963088dd70SAl Viro if (!follow_up(&nd->path)) 11971da177e4SLinus Torvalds break; 11981da177e4SLinus Torvalds } 119979ed0226SAl Viro follow_mount(&nd->path); 120031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12011da177e4SLinus Torvalds } 12021da177e4SLinus Torvalds 12031da177e4SLinus Torvalds /* 1204baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1205baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1206baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1207baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1208baa03890SNick Piggin */ 1209baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1210baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1211baa03890SNick Piggin { 1212baa03890SNick Piggin struct inode *inode = parent->d_inode; 1213baa03890SNick Piggin struct dentry *dentry; 1214baa03890SNick Piggin struct dentry *old; 1215baa03890SNick Piggin 1216baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1217baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1218baa03890SNick Piggin return ERR_PTR(-ENOENT); 1219baa03890SNick Piggin 1220baa03890SNick Piggin dentry = d_alloc(parent, name); 1221baa03890SNick Piggin if (unlikely(!dentry)) 1222baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1223baa03890SNick Piggin 1224baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1225baa03890SNick Piggin if (unlikely(old)) { 1226baa03890SNick Piggin dput(dentry); 1227baa03890SNick Piggin dentry = old; 1228baa03890SNick Piggin } 1229baa03890SNick Piggin return dentry; 1230baa03890SNick Piggin } 1231baa03890SNick Piggin 1232baa03890SNick Piggin /* 12331da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 12341da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 12351da177e4SLinus Torvalds * It _is_ time-critical. 12361da177e4SLinus Torvalds */ 12371da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 123831e6b01fSNick Piggin struct path *path, struct inode **inode) 12391da177e4SLinus Torvalds { 12404ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 124131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 12426e6b1bd1SAl Viro struct inode *dir; 12439875cf80SDavid Howells int err; 12449875cf80SDavid Howells 12453cac260aSAl Viro /* 12463cac260aSAl Viro * See if the low-level filesystem might want 12473cac260aSAl Viro * to use its own hash.. 12483cac260aSAl Viro */ 1249fb045adbSNick Piggin if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 12509875cf80SDavid Howells err = parent->d_op->d_hash(parent, nd->inode, name); 12513cac260aSAl Viro if (err < 0) 12523cac260aSAl Viro return err; 12533cac260aSAl Viro } 12541da177e4SLinus Torvalds 1255b04f784eSNick Piggin /* 1256b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1257b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1258b04f784eSNick Piggin * do the non-racy lookup, below. 1259b04f784eSNick Piggin */ 126031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 126131e6b01fSNick Piggin unsigned seq; 126231e6b01fSNick Piggin 126331e6b01fSNick Piggin *inode = nd->inode; 126431e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 126531e6b01fSNick Piggin if (!dentry) { 126631e6b01fSNick Piggin if (nameidata_drop_rcu(nd)) 126731e6b01fSNick Piggin return -ECHILD; 126831e6b01fSNick Piggin goto need_lookup; 126931e6b01fSNick Piggin } 127031e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 127131e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 127231e6b01fSNick Piggin return -ECHILD; 127331e6b01fSNick Piggin 127431e6b01fSNick Piggin nd->seq = seq; 127524643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 1276f5e1c1c1SAl Viro dentry = do_revalidate_rcu(dentry, nd); 127724643087SAl Viro if (!dentry) 127824643087SAl Viro goto need_lookup; 127924643087SAl Viro if (IS_ERR(dentry)) 128024643087SAl Viro goto fail; 128124643087SAl Viro if (!(nd->flags & LOOKUP_RCU)) 128224643087SAl Viro goto done; 128324643087SAl Viro } 128431e6b01fSNick Piggin path->mnt = mnt; 128531e6b01fSNick Piggin path->dentry = dentry; 12869875cf80SDavid Howells if (likely(__follow_mount_rcu(nd, path, inode, false))) 12879875cf80SDavid Howells return 0; 12889875cf80SDavid Howells if (nameidata_drop_rcu(nd)) 12899875cf80SDavid Howells return -ECHILD; 12909875cf80SDavid Howells /* fallthru */ 12919875cf80SDavid Howells } 129231e6b01fSNick Piggin dentry = __d_lookup(parent, name); 12931da177e4SLinus Torvalds if (!dentry) 12941da177e4SLinus Torvalds goto need_lookup; 12952e2e88eaSNick Piggin found: 129624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 129724643087SAl Viro dentry = do_revalidate(dentry, nd); 129824643087SAl Viro if (!dentry) 129924643087SAl Viro goto need_lookup; 130024643087SAl Viro if (IS_ERR(dentry)) 130124643087SAl Viro goto fail; 130224643087SAl Viro } 13031da177e4SLinus Torvalds done: 13041da177e4SLinus Torvalds path->mnt = mnt; 13051da177e4SLinus Torvalds path->dentry = dentry; 13069875cf80SDavid Howells err = follow_managed(path, nd->flags); 130789312214SIan Kent if (unlikely(err < 0)) { 130889312214SIan Kent path_put_conditional(path, nd); 13099875cf80SDavid Howells return err; 131089312214SIan Kent } 131131e6b01fSNick Piggin *inode = path->dentry->d_inode; 13121da177e4SLinus Torvalds return 0; 13131da177e4SLinus Torvalds 13141da177e4SLinus Torvalds need_lookup: 13156e6b1bd1SAl Viro dir = parent->d_inode; 131631e6b01fSNick Piggin BUG_ON(nd->inode != dir); 13176e6b1bd1SAl Viro 13186e6b1bd1SAl Viro mutex_lock(&dir->i_mutex); 13196e6b1bd1SAl Viro /* 13206e6b1bd1SAl Viro * First re-do the cached lookup just in case it was created 1321b04f784eSNick Piggin * while we waited for the directory semaphore, or the first 1322b04f784eSNick Piggin * lookup failed due to an unrelated rename. 13236e6b1bd1SAl Viro * 1324b04f784eSNick Piggin * This could use version numbering or similar to avoid unnecessary 1325b04f784eSNick Piggin * cache lookups, but then we'd have to do the first lookup in the 1326b04f784eSNick Piggin * non-racy way. However in the common case here, everything should 1327b04f784eSNick Piggin * be hot in cache, so would it be a big win? 13286e6b1bd1SAl Viro */ 13296e6b1bd1SAl Viro dentry = d_lookup(parent, name); 1330baa03890SNick Piggin if (likely(!dentry)) { 1331baa03890SNick Piggin dentry = d_alloc_and_lookup(parent, name, nd); 13326e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 13336e6b1bd1SAl Viro if (IS_ERR(dentry)) 13346e6b1bd1SAl Viro goto fail; 13356e6b1bd1SAl Viro goto done; 13366e6b1bd1SAl Viro } 13376e6b1bd1SAl Viro /* 13386e6b1bd1SAl Viro * Uhhuh! Nasty case: the cache was re-populated while 13396e6b1bd1SAl Viro * we waited on the semaphore. Need to revalidate. 13406e6b1bd1SAl Viro */ 13416e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 13422e2e88eaSNick Piggin goto found; 13431da177e4SLinus Torvalds 13441da177e4SLinus Torvalds fail: 13451da177e4SLinus Torvalds return PTR_ERR(dentry); 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds 13481da177e4SLinus Torvalds /* 13491da177e4SLinus Torvalds * Name resolution. 1350ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1351ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13521da177e4SLinus Torvalds * 1353ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1354ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13551da177e4SLinus Torvalds */ 13566de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13571da177e4SLinus Torvalds { 13581da177e4SLinus Torvalds struct path next; 13591da177e4SLinus Torvalds int err; 13601da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13611da177e4SLinus Torvalds 13621da177e4SLinus Torvalds while (*name=='/') 13631da177e4SLinus Torvalds name++; 13641da177e4SLinus Torvalds if (!*name) 13651da177e4SLinus Torvalds goto return_reval; 13661da177e4SLinus Torvalds 13671da177e4SLinus Torvalds if (nd->depth) 1368f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 13691da177e4SLinus Torvalds 13701da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13711da177e4SLinus Torvalds for(;;) { 137231e6b01fSNick Piggin struct inode *inode; 13731da177e4SLinus Torvalds unsigned long hash; 13741da177e4SLinus Torvalds struct qstr this; 13751da177e4SLinus Torvalds unsigned int c; 13761da177e4SLinus Torvalds 1377cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 137831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 1379b74c79e9SNick Piggin err = exec_permission(nd->inode, IPERM_FLAG_RCU); 138031e6b01fSNick Piggin if (err == -ECHILD) { 138131e6b01fSNick Piggin if (nameidata_drop_rcu(nd)) 138231e6b01fSNick Piggin return -ECHILD; 138331e6b01fSNick Piggin goto exec_again; 138431e6b01fSNick Piggin } 138531e6b01fSNick Piggin } else { 138631e6b01fSNick Piggin exec_again: 1387b74c79e9SNick Piggin err = exec_permission(nd->inode, 0); 138831e6b01fSNick Piggin } 13891da177e4SLinus Torvalds if (err) 13901da177e4SLinus Torvalds break; 13911da177e4SLinus Torvalds 13921da177e4SLinus Torvalds this.name = name; 13931da177e4SLinus Torvalds c = *(const unsigned char *)name; 13941da177e4SLinus Torvalds 13951da177e4SLinus Torvalds hash = init_name_hash(); 13961da177e4SLinus Torvalds do { 13971da177e4SLinus Torvalds name++; 13981da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 13991da177e4SLinus Torvalds c = *(const unsigned char *)name; 14001da177e4SLinus Torvalds } while (c && (c != '/')); 14011da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14021da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds /* remove trailing slashes? */ 14051da177e4SLinus Torvalds if (!c) 14061da177e4SLinus Torvalds goto last_component; 14071da177e4SLinus Torvalds while (*++name == '/'); 14081da177e4SLinus Torvalds if (!*name) 14091da177e4SLinus Torvalds goto last_with_slashes; 14101da177e4SLinus Torvalds 14111da177e4SLinus Torvalds /* 14121da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 14131da177e4SLinus Torvalds * to be able to know about the current root directory and 14141da177e4SLinus Torvalds * parent relationships. 14151da177e4SLinus Torvalds */ 14161da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 14171da177e4SLinus Torvalds default: 14181da177e4SLinus Torvalds break; 14191da177e4SLinus Torvalds case 2: 14201da177e4SLinus Torvalds if (this.name[1] != '.') 14211da177e4SLinus Torvalds break; 142231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 142331e6b01fSNick Piggin if (follow_dotdot_rcu(nd)) 142431e6b01fSNick Piggin return -ECHILD; 142531e6b01fSNick Piggin } else 142658c465ebSAl Viro follow_dotdot(nd); 14271da177e4SLinus Torvalds /* fallthrough */ 14281da177e4SLinus Torvalds case 1: 14291da177e4SLinus Torvalds continue; 14301da177e4SLinus Torvalds } 14311da177e4SLinus Torvalds /* This does the actual lookups.. */ 143231e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 14331da177e4SLinus Torvalds if (err) 14341da177e4SLinus Torvalds break; 14351da177e4SLinus Torvalds err = -ENOENT; 14361da177e4SLinus Torvalds if (!inode) 14371da177e4SLinus Torvalds goto out_dput; 14381da177e4SLinus Torvalds 14391da177e4SLinus Torvalds if (inode->i_op->follow_link) { 144031e6b01fSNick Piggin BUG_ON(inode != next.dentry->d_inode); 144190ebe565SAl Viro err = do_follow_link(&next, nd); 14421da177e4SLinus Torvalds if (err) 14431da177e4SLinus Torvalds goto return_err; 144431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14451da177e4SLinus Torvalds err = -ENOENT; 144631e6b01fSNick Piggin if (!nd->inode) 14471da177e4SLinus Torvalds break; 144831e6b01fSNick Piggin } else { 144909dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 145031e6b01fSNick Piggin nd->inode = inode; 145131e6b01fSNick Piggin } 14521da177e4SLinus Torvalds err = -ENOTDIR; 145331e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14541da177e4SLinus Torvalds break; 14551da177e4SLinus Torvalds continue; 14561da177e4SLinus Torvalds /* here ends the main loop */ 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds last_with_slashes: 14591da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 14601da177e4SLinus Torvalds last_component: 1461f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1462f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 14631da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 14641da177e4SLinus Torvalds goto lookup_parent; 14651da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 14661da177e4SLinus Torvalds default: 14671da177e4SLinus Torvalds break; 14681da177e4SLinus Torvalds case 2: 14691da177e4SLinus Torvalds if (this.name[1] != '.') 14701da177e4SLinus Torvalds break; 147131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 147231e6b01fSNick Piggin if (follow_dotdot_rcu(nd)) 147331e6b01fSNick Piggin return -ECHILD; 147431e6b01fSNick Piggin } else 147558c465ebSAl Viro follow_dotdot(nd); 14761da177e4SLinus Torvalds /* fallthrough */ 14771da177e4SLinus Torvalds case 1: 14781da177e4SLinus Torvalds goto return_reval; 14791da177e4SLinus Torvalds } 148031e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 14811da177e4SLinus Torvalds if (err) 14821da177e4SLinus Torvalds break; 1483db372915SDavid Howells if (inode && unlikely(inode->i_op->follow_link) && 1484db372915SDavid Howells (lookup_flags & LOOKUP_FOLLOW)) { 148531e6b01fSNick Piggin BUG_ON(inode != next.dentry->d_inode); 148690ebe565SAl Viro err = do_follow_link(&next, nd); 14871da177e4SLinus Torvalds if (err) 14881da177e4SLinus Torvalds goto return_err; 148931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 149031e6b01fSNick Piggin } else { 149109dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 149231e6b01fSNick Piggin nd->inode = inode; 149331e6b01fSNick Piggin } 14941da177e4SLinus Torvalds err = -ENOENT; 149531e6b01fSNick Piggin if (!nd->inode) 14961da177e4SLinus Torvalds break; 14971da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 14981da177e4SLinus Torvalds err = -ENOTDIR; 149931e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 15001da177e4SLinus Torvalds break; 15011da177e4SLinus Torvalds } 15021da177e4SLinus Torvalds goto return_base; 15031da177e4SLinus Torvalds lookup_parent: 15041da177e4SLinus Torvalds nd->last = this; 15051da177e4SLinus Torvalds nd->last_type = LAST_NORM; 15061da177e4SLinus Torvalds if (this.name[0] != '.') 15071da177e4SLinus Torvalds goto return_base; 15081da177e4SLinus Torvalds if (this.len == 1) 15091da177e4SLinus Torvalds nd->last_type = LAST_DOT; 15101da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 15111da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 15121da177e4SLinus Torvalds else 15131da177e4SLinus Torvalds goto return_base; 15141da177e4SLinus Torvalds return_reval: 15151da177e4SLinus Torvalds /* 15161da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 15171da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 15181da177e4SLinus Torvalds */ 1519fb045adbSNick Piggin if (need_reval_dot(nd->path.dentry)) { 15201da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 152134286d66SNick Piggin err = d_revalidate(nd->path.dentry, nd); 152234286d66SNick Piggin if (!err) 152334286d66SNick Piggin err = -ESTALE; 152434286d66SNick Piggin if (err < 0) 15251da177e4SLinus Torvalds break; 15261da177e4SLinus Torvalds } 15271da177e4SLinus Torvalds return_base: 152831e6b01fSNick Piggin if (nameidata_drop_rcu_last_maybe(nd)) 152931e6b01fSNick Piggin return -ECHILD; 15301da177e4SLinus Torvalds return 0; 15311da177e4SLinus Torvalds out_dput: 153231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) 15331d957f9bSJan Blunck path_put_conditional(&next, nd); 15341da177e4SLinus Torvalds break; 15351da177e4SLinus Torvalds } 153631e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) 15371d957f9bSJan Blunck path_put(&nd->path); 15381da177e4SLinus Torvalds return_err: 15391da177e4SLinus Torvalds return err; 15401da177e4SLinus Torvalds } 15411da177e4SLinus Torvalds 154231e6b01fSNick Piggin static inline int path_walk_rcu(const char *name, struct nameidata *nd) 154331e6b01fSNick Piggin { 154431e6b01fSNick Piggin current->total_link_count = 0; 154531e6b01fSNick Piggin 154631e6b01fSNick Piggin return link_path_walk(name, nd); 154731e6b01fSNick Piggin } 154831e6b01fSNick Piggin 154931e6b01fSNick Piggin static inline int path_walk_simple(const char *name, struct nameidata *nd) 155031e6b01fSNick Piggin { 155131e6b01fSNick Piggin current->total_link_count = 0; 155231e6b01fSNick Piggin 155331e6b01fSNick Piggin return link_path_walk(name, nd); 155431e6b01fSNick Piggin } 155531e6b01fSNick Piggin 1556fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 15571da177e4SLinus Torvalds { 15586de88d72SAl Viro struct path save = nd->path; 15596de88d72SAl Viro int result; 15606de88d72SAl Viro 15611da177e4SLinus Torvalds current->total_link_count = 0; 15626de88d72SAl Viro 15636de88d72SAl Viro /* make sure the stuff we saved doesn't go away */ 15646de88d72SAl Viro path_get(&save); 15656de88d72SAl Viro 15666de88d72SAl Viro result = link_path_walk(name, nd); 15676de88d72SAl Viro if (result == -ESTALE) { 15686de88d72SAl Viro /* nd->path had been dropped */ 15696de88d72SAl Viro current->total_link_count = 0; 15706de88d72SAl Viro nd->path = save; 15716de88d72SAl Viro path_get(&nd->path); 15726de88d72SAl Viro nd->flags |= LOOKUP_REVAL; 15736de88d72SAl Viro result = link_path_walk(name, nd); 15746de88d72SAl Viro } 15756de88d72SAl Viro 15766de88d72SAl Viro path_put(&save); 15776de88d72SAl Viro 15786de88d72SAl Viro return result; 15791da177e4SLinus Torvalds } 15801da177e4SLinus Torvalds 158131e6b01fSNick Piggin static void path_finish_rcu(struct nameidata *nd) 158231e6b01fSNick Piggin { 158331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 158431e6b01fSNick Piggin /* RCU dangling. Cancel it. */ 158531e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 158631e6b01fSNick Piggin nd->root.mnt = NULL; 158731e6b01fSNick Piggin rcu_read_unlock(); 158831e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 158931e6b01fSNick Piggin } 159031e6b01fSNick Piggin if (nd->file) 159131e6b01fSNick Piggin fput(nd->file); 159231e6b01fSNick Piggin } 159331e6b01fSNick Piggin 159431e6b01fSNick Piggin static int path_init_rcu(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 159531e6b01fSNick Piggin { 159631e6b01fSNick Piggin int retval = 0; 159731e6b01fSNick Piggin int fput_needed; 159831e6b01fSNick Piggin struct file *file; 159931e6b01fSNick Piggin 160031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 160131e6b01fSNick Piggin nd->flags = flags | LOOKUP_RCU; 160231e6b01fSNick Piggin nd->depth = 0; 160331e6b01fSNick Piggin nd->root.mnt = NULL; 160431e6b01fSNick Piggin nd->file = NULL; 160531e6b01fSNick Piggin 160631e6b01fSNick Piggin if (*name=='/') { 160731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1608c28cc364SNick Piggin unsigned seq; 160931e6b01fSNick Piggin 161031e6b01fSNick Piggin br_read_lock(vfsmount_lock); 161131e6b01fSNick Piggin rcu_read_lock(); 161231e6b01fSNick Piggin 1613c28cc364SNick Piggin do { 1614c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 161531e6b01fSNick Piggin nd->root = fs->root; 161631e6b01fSNick Piggin nd->path = nd->root; 1617c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1618c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 161931e6b01fSNick Piggin 162031e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 162131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1622c28cc364SNick Piggin unsigned seq; 162331e6b01fSNick Piggin 162431e6b01fSNick Piggin br_read_lock(vfsmount_lock); 162531e6b01fSNick Piggin rcu_read_lock(); 162631e6b01fSNick Piggin 1627c28cc364SNick Piggin do { 1628c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 162931e6b01fSNick Piggin nd->path = fs->pwd; 1630c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1631c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1632c28cc364SNick Piggin 163331e6b01fSNick Piggin } else { 163431e6b01fSNick Piggin struct dentry *dentry; 163531e6b01fSNick Piggin 163631e6b01fSNick Piggin file = fget_light(dfd, &fput_needed); 163731e6b01fSNick Piggin retval = -EBADF; 163831e6b01fSNick Piggin if (!file) 163931e6b01fSNick Piggin goto out_fail; 164031e6b01fSNick Piggin 164131e6b01fSNick Piggin dentry = file->f_path.dentry; 164231e6b01fSNick Piggin 164331e6b01fSNick Piggin retval = -ENOTDIR; 164431e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 164531e6b01fSNick Piggin goto fput_fail; 164631e6b01fSNick Piggin 164731e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 164831e6b01fSNick Piggin if (retval) 164931e6b01fSNick Piggin goto fput_fail; 165031e6b01fSNick Piggin 165131e6b01fSNick Piggin nd->path = file->f_path; 165231e6b01fSNick Piggin if (fput_needed) 165331e6b01fSNick Piggin nd->file = file; 165431e6b01fSNick Piggin 1655c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 165631e6b01fSNick Piggin br_read_lock(vfsmount_lock); 165731e6b01fSNick Piggin rcu_read_lock(); 165831e6b01fSNick Piggin } 165931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 166031e6b01fSNick Piggin return 0; 166131e6b01fSNick Piggin 166231e6b01fSNick Piggin fput_fail: 166331e6b01fSNick Piggin fput_light(file, fput_needed); 166431e6b01fSNick Piggin out_fail: 166531e6b01fSNick Piggin return retval; 166631e6b01fSNick Piggin } 166731e6b01fSNick Piggin 16689b4a9b14SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 16691da177e4SLinus Torvalds { 1670ea3834d9SPrasanna Meda int retval = 0; 1671170aa3d0SUlrich Drepper int fput_needed; 1672170aa3d0SUlrich Drepper struct file *file; 16731da177e4SLinus Torvalds 16741da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 16751da177e4SLinus Torvalds nd->flags = flags; 16761da177e4SLinus Torvalds nd->depth = 0; 16772a737871SAl Viro nd->root.mnt = NULL; 16781da177e4SLinus Torvalds 16791da177e4SLinus Torvalds if (*name=='/') { 16802a737871SAl Viro set_root(nd); 16812a737871SAl Viro nd->path = nd->root; 16822a737871SAl Viro path_get(&nd->root); 16835590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1684f7ad3c6bSMiklos Szeredi get_fs_pwd(current->fs, &nd->path); 16855590ff0dSUlrich Drepper } else { 16865590ff0dSUlrich Drepper struct dentry *dentry; 16875590ff0dSUlrich Drepper 16885590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 16895590ff0dSUlrich Drepper retval = -EBADF; 1690170aa3d0SUlrich Drepper if (!file) 16916d09bb62STrond Myklebust goto out_fail; 16925590ff0dSUlrich Drepper 16930f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 16945590ff0dSUlrich Drepper 16955590ff0dSUlrich Drepper retval = -ENOTDIR; 1696170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 16976d09bb62STrond Myklebust goto fput_fail; 16985590ff0dSUlrich Drepper 16995590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1700170aa3d0SUlrich Drepper if (retval) 17016d09bb62STrond Myklebust goto fput_fail; 17025590ff0dSUlrich Drepper 17035dd784d0SJan Blunck nd->path = file->f_path; 17045dd784d0SJan Blunck path_get(&file->f_path); 17055590ff0dSUlrich Drepper 17065590ff0dSUlrich Drepper fput_light(file, fput_needed); 17071da177e4SLinus Torvalds } 170831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17099b4a9b14SAl Viro return 0; 17102dfdd266SJosef 'Jeff' Sipek 17119b4a9b14SAl Viro fput_fail: 17129b4a9b14SAl Viro fput_light(file, fput_needed); 17139b4a9b14SAl Viro out_fail: 17149b4a9b14SAl Viro return retval; 17159b4a9b14SAl Viro } 17169b4a9b14SAl Viro 17179b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 17189b4a9b14SAl Viro static int do_path_lookup(int dfd, const char *name, 17199b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17209b4a9b14SAl Viro { 172131e6b01fSNick Piggin int retval; 172231e6b01fSNick Piggin 172331e6b01fSNick Piggin /* 172431e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 172531e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 172631e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 172731e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 172831e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 172931e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 173031e6b01fSNick Piggin * analogue, foo_rcu(). 173131e6b01fSNick Piggin * 173231e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 173331e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 173431e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 173531e6b01fSNick Piggin * be able to complete). 173631e6b01fSNick Piggin */ 173731e6b01fSNick Piggin retval = path_init_rcu(dfd, name, flags, nd); 173831e6b01fSNick Piggin if (unlikely(retval)) 173931e6b01fSNick Piggin return retval; 174031e6b01fSNick Piggin retval = path_walk_rcu(name, nd); 174131e6b01fSNick Piggin path_finish_rcu(nd); 17422a737871SAl Viro if (nd->root.mnt) { 17432a737871SAl Viro path_put(&nd->root); 17442a737871SAl Viro nd->root.mnt = NULL; 17452a737871SAl Viro } 174631e6b01fSNick Piggin 174731e6b01fSNick Piggin if (unlikely(retval == -ECHILD || retval == -ESTALE)) { 174831e6b01fSNick Piggin /* slower, locked walk */ 174931e6b01fSNick Piggin if (retval == -ESTALE) 175031e6b01fSNick Piggin flags |= LOOKUP_REVAL; 175131e6b01fSNick Piggin retval = path_init(dfd, name, flags, nd); 175231e6b01fSNick Piggin if (unlikely(retval)) 175331e6b01fSNick Piggin return retval; 175431e6b01fSNick Piggin retval = path_walk(name, nd); 175531e6b01fSNick Piggin if (nd->root.mnt) { 175631e6b01fSNick Piggin path_put(&nd->root); 175731e6b01fSNick Piggin nd->root.mnt = NULL; 175831e6b01fSNick Piggin } 175931e6b01fSNick Piggin } 176031e6b01fSNick Piggin 176131e6b01fSNick Piggin if (likely(!retval)) { 176231e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 176331e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 176431e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 176531e6b01fSNick Piggin } 176631e6b01fSNick Piggin } 176731e6b01fSNick Piggin 1768170aa3d0SUlrich Drepper return retval; 17691da177e4SLinus Torvalds } 17701da177e4SLinus Torvalds 1771fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 17725590ff0dSUlrich Drepper struct nameidata *nd) 17735590ff0dSUlrich Drepper { 17745590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 17755590ff0dSUlrich Drepper } 17765590ff0dSUlrich Drepper 1777d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1778d1811465SAl Viro { 1779d1811465SAl Viro struct nameidata nd; 1780d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1781d1811465SAl Viro if (!res) 1782d1811465SAl Viro *path = nd.path; 1783d1811465SAl Viro return res; 1784d1811465SAl Viro } 1785d1811465SAl Viro 178616f18200SJosef 'Jeff' Sipek /** 178716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 178816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 178916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 179016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 179116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 179216f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 179316f18200SJosef 'Jeff' Sipek */ 179416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 179516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 179616f18200SJosef 'Jeff' Sipek struct nameidata *nd) 179716f18200SJosef 'Jeff' Sipek { 179816f18200SJosef 'Jeff' Sipek int retval; 179916f18200SJosef 'Jeff' Sipek 180016f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 180116f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 180216f18200SJosef 'Jeff' Sipek nd->flags = flags; 180316f18200SJosef 'Jeff' Sipek nd->depth = 0; 180416f18200SJosef 'Jeff' Sipek 1805c8e7f449SJan Blunck nd->path.dentry = dentry; 1806c8e7f449SJan Blunck nd->path.mnt = mnt; 1807c8e7f449SJan Blunck path_get(&nd->path); 18085b857119SAl Viro nd->root = nd->path; 18095b857119SAl Viro path_get(&nd->root); 181031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 181116f18200SJosef 'Jeff' Sipek 181216f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 18134ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 181431e6b01fSNick Piggin nd->inode)) 18154ac91378SJan Blunck audit_inode(name, nd->path.dentry); 181616f18200SJosef 'Jeff' Sipek 18172a737871SAl Viro path_put(&nd->root); 18182a737871SAl Viro nd->root.mnt = NULL; 181916f18200SJosef 'Jeff' Sipek 18202a737871SAl Viro return retval; 182116f18200SJosef 'Jeff' Sipek } 182216f18200SJosef 'Jeff' Sipek 1823eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1824eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 18251da177e4SLinus Torvalds { 182681fca444SChristoph Hellwig struct inode *inode = base->d_inode; 18271da177e4SLinus Torvalds struct dentry *dentry; 18281da177e4SLinus Torvalds int err; 18291da177e4SLinus Torvalds 1830b74c79e9SNick Piggin err = exec_permission(inode, 0); 183181fca444SChristoph Hellwig if (err) 183281fca444SChristoph Hellwig return ERR_PTR(err); 18331da177e4SLinus Torvalds 18341da177e4SLinus Torvalds /* 18351da177e4SLinus Torvalds * See if the low-level filesystem might want 18361da177e4SLinus Torvalds * to use its own hash.. 18371da177e4SLinus Torvalds */ 1838fb045adbSNick Piggin if (base->d_flags & DCACHE_OP_HASH) { 1839b1e6a015SNick Piggin err = base->d_op->d_hash(base, inode, name); 18401da177e4SLinus Torvalds dentry = ERR_PTR(err); 18411da177e4SLinus Torvalds if (err < 0) 18421da177e4SLinus Torvalds goto out; 18431da177e4SLinus Torvalds } 18441da177e4SLinus Torvalds 1845b04f784eSNick Piggin /* 1846b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1847b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1848b04f784eSNick Piggin * a double lookup. 18496e6b1bd1SAl Viro */ 18506e6b1bd1SAl Viro dentry = d_lookup(base, name); 18516e6b1bd1SAl Viro 1852fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 18536e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 18546e6b1bd1SAl Viro 18551da177e4SLinus Torvalds if (!dentry) 1856baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 18571da177e4SLinus Torvalds out: 18581da177e4SLinus Torvalds return dentry; 18591da177e4SLinus Torvalds } 18601da177e4SLinus Torvalds 1861057f6c01SJames Morris /* 1862057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1863057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1864057f6c01SJames Morris * SMP-safe. 1865057f6c01SJames Morris */ 1866a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 18671da177e4SLinus Torvalds { 18684ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 18691da177e4SLinus Torvalds } 18701da177e4SLinus Torvalds 1871eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1872eead1911SChristoph Hellwig struct dentry *base, int len) 18731da177e4SLinus Torvalds { 18741da177e4SLinus Torvalds unsigned long hash; 18751da177e4SLinus Torvalds unsigned int c; 18761da177e4SLinus Torvalds 1877057f6c01SJames Morris this->name = name; 1878057f6c01SJames Morris this->len = len; 18791da177e4SLinus Torvalds if (!len) 1880057f6c01SJames Morris return -EACCES; 18811da177e4SLinus Torvalds 18821da177e4SLinus Torvalds hash = init_name_hash(); 18831da177e4SLinus Torvalds while (len--) { 18841da177e4SLinus Torvalds c = *(const unsigned char *)name++; 18851da177e4SLinus Torvalds if (c == '/' || c == '\0') 1886057f6c01SJames Morris return -EACCES; 18871da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 18881da177e4SLinus Torvalds } 1889057f6c01SJames Morris this->hash = end_name_hash(hash); 1890057f6c01SJames Morris return 0; 1891057f6c01SJames Morris } 18921da177e4SLinus Torvalds 1893eead1911SChristoph Hellwig /** 1894a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1895eead1911SChristoph Hellwig * @name: pathname component to lookup 1896eead1911SChristoph Hellwig * @base: base directory to lookup from 1897eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1898eead1911SChristoph Hellwig * 1899a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1900a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1901eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1902eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1903eead1911SChristoph Hellwig */ 1904057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1905057f6c01SJames Morris { 1906057f6c01SJames Morris int err; 1907057f6c01SJames Morris struct qstr this; 1908057f6c01SJames Morris 19092f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 19102f9092e1SDavid Woodhouse 1911057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1912057f6c01SJames Morris if (err) 1913057f6c01SJames Morris return ERR_PTR(err); 1914eead1911SChristoph Hellwig 191549705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1916057f6c01SJames Morris } 1917057f6c01SJames Morris 19182d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 19192d8f3038SAl Viro struct path *path) 19201da177e4SLinus Torvalds { 19212d8f3038SAl Viro struct nameidata nd; 19221da177e4SLinus Torvalds char *tmp = getname(name); 19231da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19241da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19252d8f3038SAl Viro 19262d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19272d8f3038SAl Viro 19282d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19291da177e4SLinus Torvalds putname(tmp); 19302d8f3038SAl Viro if (!err) 19312d8f3038SAl Viro *path = nd.path; 19321da177e4SLinus Torvalds } 19331da177e4SLinus Torvalds return err; 19341da177e4SLinus Torvalds } 19351da177e4SLinus Torvalds 19362ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 19372ad94ae6SAl Viro struct nameidata *nd, char **name) 19382ad94ae6SAl Viro { 19392ad94ae6SAl Viro char *s = getname(path); 19402ad94ae6SAl Viro int error; 19412ad94ae6SAl Viro 19422ad94ae6SAl Viro if (IS_ERR(s)) 19432ad94ae6SAl Viro return PTR_ERR(s); 19442ad94ae6SAl Viro 19452ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 19462ad94ae6SAl Viro if (error) 19472ad94ae6SAl Viro putname(s); 19482ad94ae6SAl Viro else 19492ad94ae6SAl Viro *name = s; 19502ad94ae6SAl Viro 19512ad94ae6SAl Viro return error; 19522ad94ae6SAl Viro } 19532ad94ae6SAl Viro 19541da177e4SLinus Torvalds /* 19551da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 19561da177e4SLinus Torvalds * minimal. 19571da177e4SLinus Torvalds */ 19581da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 19591da177e4SLinus Torvalds { 1960da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1961da9592edSDavid Howells 19621da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 19631da177e4SLinus Torvalds return 0; 1964da9592edSDavid Howells if (inode->i_uid == fsuid) 19651da177e4SLinus Torvalds return 0; 1966da9592edSDavid Howells if (dir->i_uid == fsuid) 19671da177e4SLinus Torvalds return 0; 19681da177e4SLinus Torvalds return !capable(CAP_FOWNER); 19691da177e4SLinus Torvalds } 19701da177e4SLinus Torvalds 19711da177e4SLinus Torvalds /* 19721da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 19731da177e4SLinus Torvalds * whether the type of victim is right. 19741da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 19751da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 19761da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 19771da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 19781da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 19791da177e4SLinus Torvalds * a. be owner of dir, or 19801da177e4SLinus Torvalds * b. be owner of victim, or 19811da177e4SLinus Torvalds * c. have CAP_FOWNER capability 19821da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 19831da177e4SLinus Torvalds * links pointing to it. 19841da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 19851da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 19861da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 19871da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 19881da177e4SLinus Torvalds * nfs_async_unlink(). 19891da177e4SLinus Torvalds */ 1990858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 19911da177e4SLinus Torvalds { 19921da177e4SLinus Torvalds int error; 19931da177e4SLinus Torvalds 19941da177e4SLinus Torvalds if (!victim->d_inode) 19951da177e4SLinus Torvalds return -ENOENT; 19961da177e4SLinus Torvalds 19971da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1998cccc6bbaSAl Viro audit_inode_child(victim, dir); 19991da177e4SLinus Torvalds 2000f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20011da177e4SLinus Torvalds if (error) 20021da177e4SLinus Torvalds return error; 20031da177e4SLinus Torvalds if (IS_APPEND(dir)) 20041da177e4SLinus Torvalds return -EPERM; 20051da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2006f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20071da177e4SLinus Torvalds return -EPERM; 20081da177e4SLinus Torvalds if (isdir) { 20091da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20101da177e4SLinus Torvalds return -ENOTDIR; 20111da177e4SLinus Torvalds if (IS_ROOT(victim)) 20121da177e4SLinus Torvalds return -EBUSY; 20131da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20141da177e4SLinus Torvalds return -EISDIR; 20151da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20161da177e4SLinus Torvalds return -ENOENT; 20171da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20181da177e4SLinus Torvalds return -EBUSY; 20191da177e4SLinus Torvalds return 0; 20201da177e4SLinus Torvalds } 20211da177e4SLinus Torvalds 20221da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20231da177e4SLinus Torvalds * dir. 20241da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20251da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20261da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20271da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20281da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20291da177e4SLinus Torvalds */ 2030a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 20311da177e4SLinus Torvalds { 20321da177e4SLinus Torvalds if (child->d_inode) 20331da177e4SLinus Torvalds return -EEXIST; 20341da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20351da177e4SLinus Torvalds return -ENOENT; 2036f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 20371da177e4SLinus Torvalds } 20381da177e4SLinus Torvalds 20391da177e4SLinus Torvalds /* 20401da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 20411da177e4SLinus Torvalds */ 20421da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 20431da177e4SLinus Torvalds { 20441da177e4SLinus Torvalds struct dentry *p; 20451da177e4SLinus Torvalds 20461da177e4SLinus Torvalds if (p1 == p2) { 2047f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 20481da177e4SLinus Torvalds return NULL; 20491da177e4SLinus Torvalds } 20501da177e4SLinus Torvalds 2051a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20521da177e4SLinus Torvalds 2053e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2054e2761a11SOGAWA Hirofumi if (p) { 2055f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2056f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 20571da177e4SLinus Torvalds return p; 20581da177e4SLinus Torvalds } 20591da177e4SLinus Torvalds 2060e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2061e2761a11SOGAWA Hirofumi if (p) { 2062f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2063f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20641da177e4SLinus Torvalds return p; 20651da177e4SLinus Torvalds } 20661da177e4SLinus Torvalds 2067f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2068f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20691da177e4SLinus Torvalds return NULL; 20701da177e4SLinus Torvalds } 20711da177e4SLinus Torvalds 20721da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 20731da177e4SLinus Torvalds { 20741b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 20751da177e4SLinus Torvalds if (p1 != p2) { 20761b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2077a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20781da177e4SLinus Torvalds } 20791da177e4SLinus Torvalds } 20801da177e4SLinus Torvalds 20811da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 20821da177e4SLinus Torvalds struct nameidata *nd) 20831da177e4SLinus Torvalds { 2084a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20851da177e4SLinus Torvalds 20861da177e4SLinus Torvalds if (error) 20871da177e4SLinus Torvalds return error; 20881da177e4SLinus Torvalds 2089acfa4380SAl Viro if (!dir->i_op->create) 20901da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 20911da177e4SLinus Torvalds mode &= S_IALLUGO; 20921da177e4SLinus Torvalds mode |= S_IFREG; 20931da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 20941da177e4SLinus Torvalds if (error) 20951da177e4SLinus Torvalds return error; 20961da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 2097a74574aaSStephen Smalley if (!error) 2098f38aa942SAmy Griffis fsnotify_create(dir, dentry); 20991da177e4SLinus Torvalds return error; 21001da177e4SLinus Torvalds } 21011da177e4SLinus Torvalds 21023fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 21031da177e4SLinus Torvalds { 21043fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21051da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21061da177e4SLinus Torvalds int error; 21071da177e4SLinus Torvalds 21081da177e4SLinus Torvalds if (!inode) 21091da177e4SLinus Torvalds return -ENOENT; 21101da177e4SLinus Torvalds 2111c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2112c8fe8f30SChristoph Hellwig case S_IFLNK: 21131da177e4SLinus Torvalds return -ELOOP; 2114c8fe8f30SChristoph Hellwig case S_IFDIR: 2115c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21161da177e4SLinus Torvalds return -EISDIR; 2117c8fe8f30SChristoph Hellwig break; 2118c8fe8f30SChristoph Hellwig case S_IFBLK: 2119c8fe8f30SChristoph Hellwig case S_IFCHR: 21203fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21211da177e4SLinus Torvalds return -EACCES; 2122c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2123c8fe8f30SChristoph Hellwig case S_IFIFO: 2124c8fe8f30SChristoph Hellwig case S_IFSOCK: 21251da177e4SLinus Torvalds flag &= ~O_TRUNC; 2126c8fe8f30SChristoph Hellwig break; 21274a3fd211SDave Hansen } 2128b41572e9SDave Hansen 21293fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2130b41572e9SDave Hansen if (error) 2131b41572e9SDave Hansen return error; 21326146f0d5SMimi Zohar 21331da177e4SLinus Torvalds /* 21341da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 21351da177e4SLinus Torvalds */ 21361da177e4SLinus Torvalds if (IS_APPEND(inode)) { 21378737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 21387715b521SAl Viro return -EPERM; 21391da177e4SLinus Torvalds if (flag & O_TRUNC) 21407715b521SAl Viro return -EPERM; 21411da177e4SLinus Torvalds } 21421da177e4SLinus Torvalds 21431da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 21447715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 21457715b521SAl Viro return -EPERM; 21461da177e4SLinus Torvalds 21471da177e4SLinus Torvalds /* 21481da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 21491da177e4SLinus Torvalds */ 2150b65a9cfcSAl Viro return break_lease(inode, flag); 21517715b521SAl Viro } 21527715b521SAl Viro 2153e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 21547715b521SAl Viro { 2155e1181ee6SJeff Layton struct path *path = &filp->f_path; 21567715b521SAl Viro struct inode *inode = path->dentry->d_inode; 21577715b521SAl Viro int error = get_write_access(inode); 21581da177e4SLinus Torvalds if (error) 21597715b521SAl Viro return error; 21601da177e4SLinus Torvalds /* 21611da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 21621da177e4SLinus Torvalds */ 21631da177e4SLinus Torvalds error = locks_verify_locked(inode); 2164be6d3e56SKentaro Takeda if (!error) 2165ea0d3ab2STetsuo Handa error = security_path_truncate(path); 21661da177e4SLinus Torvalds if (!error) { 21677715b521SAl Viro error = do_truncate(path->dentry, 0, 2168d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2169e1181ee6SJeff Layton filp); 21701da177e4SLinus Torvalds } 21711da177e4SLinus Torvalds put_write_access(inode); 2172acd0c935SMimi Zohar return error; 21731da177e4SLinus Torvalds } 21741da177e4SLinus Torvalds 2175d57999e1SDave Hansen /* 2176d57999e1SDave Hansen * Be careful about ever adding any more callers of this 2177d57999e1SDave Hansen * function. Its flags must be in the namei format, not 2178d57999e1SDave Hansen * what get passed to sys_open(). 2179d57999e1SDave Hansen */ 2180d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 21818737c930SAl Viro int open_flag, int mode) 2182aab520e2SDave Hansen { 2183aab520e2SDave Hansen int error; 21844ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 2185aab520e2SDave Hansen 2186aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 2187ce3b0f8dSAl Viro mode &= ~current_umask(); 2188be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 2189be6d3e56SKentaro Takeda if (error) 2190be6d3e56SKentaro Takeda goto out_unlock; 2191aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 2192be6d3e56SKentaro Takeda out_unlock: 2193aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 21944ac91378SJan Blunck dput(nd->path.dentry); 21954ac91378SJan Blunck nd->path.dentry = path->dentry; 219631e6b01fSNick Piggin 2197aab520e2SDave Hansen if (error) 2198aab520e2SDave Hansen return error; 2199aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 22008737c930SAl Viro return may_open(&nd->path, 0, open_flag & ~O_TRUNC); 2201aab520e2SDave Hansen } 2202aab520e2SDave Hansen 22031da177e4SLinus Torvalds /* 2204d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2205d57999e1SDave Hansen * 00 - read-only 2206d57999e1SDave Hansen * 01 - write-only 2207d57999e1SDave Hansen * 10 - read-write 2208d57999e1SDave Hansen * 11 - special 2209d57999e1SDave Hansen * it is changed into 2210d57999e1SDave Hansen * 00 - no permissions needed 2211d57999e1SDave Hansen * 01 - read-permission 2212d57999e1SDave Hansen * 10 - write-permission 2213d57999e1SDave Hansen * 11 - read-write 2214d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2215d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2216d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2217d57999e1SDave Hansen * later). 2218d57999e1SDave Hansen * 2219d57999e1SDave Hansen */ 2220d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2221d57999e1SDave Hansen { 2222d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2223d57999e1SDave Hansen flag++; 2224d57999e1SDave Hansen return flag; 2225d57999e1SDave Hansen } 2226d57999e1SDave Hansen 22277715b521SAl Viro static int open_will_truncate(int flag, struct inode *inode) 22284a3fd211SDave Hansen { 2229d57999e1SDave Hansen /* 22304a3fd211SDave Hansen * We'll never write to the fs underlying 22314a3fd211SDave Hansen * a device file. 22324a3fd211SDave Hansen */ 22334a3fd211SDave Hansen if (special_file(inode->i_mode)) 22344a3fd211SDave Hansen return 0; 22354a3fd211SDave Hansen return (flag & O_TRUNC); 22364a3fd211SDave Hansen } 22374a3fd211SDave Hansen 2238648fa861SAl Viro static struct file *finish_open(struct nameidata *nd, 22399a66179eSAl Viro int open_flag, int acc_mode) 2240648fa861SAl Viro { 2241648fa861SAl Viro struct file *filp; 2242648fa861SAl Viro int will_truncate; 2243648fa861SAl Viro int error; 2244648fa861SAl Viro 22459a66179eSAl Viro will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode); 2246648fa861SAl Viro if (will_truncate) { 2247648fa861SAl Viro error = mnt_want_write(nd->path.mnt); 2248648fa861SAl Viro if (error) 2249648fa861SAl Viro goto exit; 2250648fa861SAl Viro } 2251648fa861SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2252648fa861SAl Viro if (error) { 2253648fa861SAl Viro if (will_truncate) 2254648fa861SAl Viro mnt_drop_write(nd->path.mnt); 2255648fa861SAl Viro goto exit; 2256648fa861SAl Viro } 2257648fa861SAl Viro filp = nameidata_to_filp(nd); 2258648fa861SAl Viro if (!IS_ERR(filp)) { 2259648fa861SAl Viro error = ima_file_check(filp, acc_mode); 2260648fa861SAl Viro if (error) { 2261648fa861SAl Viro fput(filp); 2262648fa861SAl Viro filp = ERR_PTR(error); 2263648fa861SAl Viro } 2264648fa861SAl Viro } 2265648fa861SAl Viro if (!IS_ERR(filp)) { 2266648fa861SAl Viro if (will_truncate) { 2267e1181ee6SJeff Layton error = handle_truncate(filp); 2268648fa861SAl Viro if (error) { 2269648fa861SAl Viro fput(filp); 2270648fa861SAl Viro filp = ERR_PTR(error); 2271648fa861SAl Viro } 2272648fa861SAl Viro } 2273648fa861SAl Viro } 2274648fa861SAl Viro /* 2275648fa861SAl Viro * It is now safe to drop the mnt write 2276648fa861SAl Viro * because the filp has had a write taken 2277648fa861SAl Viro * on its behalf. 2278648fa861SAl Viro */ 2279648fa861SAl Viro if (will_truncate) 2280648fa861SAl Viro mnt_drop_write(nd->path.mnt); 2281d893f1bcSAl Viro path_put(&nd->path); 2282648fa861SAl Viro return filp; 2283648fa861SAl Viro 2284648fa861SAl Viro exit: 2285648fa861SAl Viro path_put(&nd->path); 2286648fa861SAl Viro return ERR_PTR(error); 2287648fa861SAl Viro } 2288648fa861SAl Viro 228931e6b01fSNick Piggin /* 229031e6b01fSNick Piggin * Handle O_CREAT case for do_filp_open 229131e6b01fSNick Piggin */ 2292fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 22935b369df8SAl Viro int open_flag, int acc_mode, 22943e297b61SAl Viro int mode, const char *pathname) 2295fb1cc555SAl Viro { 2296a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2297fb1cc555SAl Viro struct file *filp; 22981f36f774SAl Viro int error = -EISDIR; 2299fb1cc555SAl Viro 23001f36f774SAl Viro switch (nd->last_type) { 23011f36f774SAl Viro case LAST_DOTDOT: 23021f36f774SAl Viro follow_dotdot(nd); 23031f36f774SAl Viro dir = nd->path.dentry; 2304176306f5SNeil Brown case LAST_DOT: 2305fb045adbSNick Piggin if (need_reval_dot(dir)) { 2306f20877d9SJ. R. Okajima int status = d_revalidate(nd->path.dentry, nd); 2307f20877d9SJ. R. Okajima if (!status) 2308f20877d9SJ. R. Okajima status = -ESTALE; 2309f20877d9SJ. R. Okajima if (status < 0) { 2310f20877d9SJ. R. Okajima error = status; 2311a2c36b45SAl Viro goto exit; 23121f36f774SAl Viro } 2313f20877d9SJ. R. Okajima } 23141f36f774SAl Viro /* fallthrough */ 23151f36f774SAl Viro case LAST_ROOT: 23161f36f774SAl Viro goto exit; 23171f36f774SAl Viro case LAST_BIND: 23181f36f774SAl Viro audit_inode(pathname, dir); 23191f36f774SAl Viro goto ok; 23201f36f774SAl Viro } 2321a2c36b45SAl Viro 23221f36f774SAl Viro /* trailing slashes? */ 232331e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 23241f36f774SAl Viro goto exit; 23251f36f774SAl Viro 2326a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2327a1e28038SAl Viro 2328a1e28038SAl Viro path->dentry = lookup_hash(nd); 2329a1e28038SAl Viro path->mnt = nd->path.mnt; 2330a1e28038SAl Viro 2331fb1cc555SAl Viro error = PTR_ERR(path->dentry); 2332fb1cc555SAl Viro if (IS_ERR(path->dentry)) { 2333fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2334fb1cc555SAl Viro goto exit; 2335fb1cc555SAl Viro } 2336fb1cc555SAl Viro 2337fb1cc555SAl Viro if (IS_ERR(nd->intent.open.file)) { 2338fb1cc555SAl Viro error = PTR_ERR(nd->intent.open.file); 2339fb1cc555SAl Viro goto exit_mutex_unlock; 2340fb1cc555SAl Viro } 2341fb1cc555SAl Viro 2342fb1cc555SAl Viro /* Negative dentry, just create the file */ 2343fb1cc555SAl Viro if (!path->dentry->d_inode) { 2344fb1cc555SAl Viro /* 2345fb1cc555SAl Viro * This write is needed to ensure that a 2346fb1cc555SAl Viro * ro->rw transition does not occur between 2347fb1cc555SAl Viro * the time when the file is created and when 2348fb1cc555SAl Viro * a permanent write count is taken through 2349fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2350fb1cc555SAl Viro */ 2351fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2352fb1cc555SAl Viro if (error) 2353fb1cc555SAl Viro goto exit_mutex_unlock; 2354fb1cc555SAl Viro error = __open_namei_create(nd, path, open_flag, mode); 2355fb1cc555SAl Viro if (error) { 2356fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 2357fb1cc555SAl Viro goto exit; 2358fb1cc555SAl Viro } 2359fb1cc555SAl Viro filp = nameidata_to_filp(nd); 2360fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 2361d893f1bcSAl Viro path_put(&nd->path); 2362fb1cc555SAl Viro if (!IS_ERR(filp)) { 2363fb1cc555SAl Viro error = ima_file_check(filp, acc_mode); 2364fb1cc555SAl Viro if (error) { 2365fb1cc555SAl Viro fput(filp); 2366fb1cc555SAl Viro filp = ERR_PTR(error); 2367fb1cc555SAl Viro } 2368fb1cc555SAl Viro } 2369fb1cc555SAl Viro return filp; 2370fb1cc555SAl Viro } 2371fb1cc555SAl Viro 2372fb1cc555SAl Viro /* 2373fb1cc555SAl Viro * It already exists. 2374fb1cc555SAl Viro */ 2375fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2376fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2377fb1cc555SAl Viro 2378fb1cc555SAl Viro error = -EEXIST; 23795b369df8SAl Viro if (open_flag & O_EXCL) 2380fb1cc555SAl Viro goto exit_dput; 2381fb1cc555SAl Viro 23829875cf80SDavid Howells error = follow_managed(path, nd->flags); 23839875cf80SDavid Howells if (error < 0) 2384fb1cc555SAl Viro goto exit_dput; 2385fb1cc555SAl Viro 2386fb1cc555SAl Viro error = -ENOENT; 2387fb1cc555SAl Viro if (!path->dentry->d_inode) 2388fb1cc555SAl Viro goto exit_dput; 23899e67f361SAl Viro 23909e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2391fb1cc555SAl Viro return NULL; 2392fb1cc555SAl Viro 2393fb1cc555SAl Viro path_to_nameidata(path, nd); 239431e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2395fb1cc555SAl Viro error = -EISDIR; 239631e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2397fb1cc555SAl Viro goto exit; 239867ee3ad2SAl Viro ok: 23999a66179eSAl Viro filp = finish_open(nd, open_flag, acc_mode); 2400fb1cc555SAl Viro return filp; 2401fb1cc555SAl Viro 2402fb1cc555SAl Viro exit_mutex_unlock: 2403fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2404fb1cc555SAl Viro exit_dput: 2405fb1cc555SAl Viro path_put_conditional(path, nd); 2406fb1cc555SAl Viro exit: 2407fb1cc555SAl Viro path_put(&nd->path); 2408fb1cc555SAl Viro return ERR_PTR(error); 2409fb1cc555SAl Viro } 2410fb1cc555SAl Viro 24114a3fd211SDave Hansen /* 24124a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 24134a3fd211SDave Hansen * are not the same as in the local variable "flag". See 24144a3fd211SDave Hansen * open_to_namei_flags() for more details. 24151da177e4SLinus Torvalds */ 2416a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 24176e8341a1SAl Viro int open_flag, int mode, int acc_mode) 24181da177e4SLinus Torvalds { 24194a3fd211SDave Hansen struct file *filp; 2420a70e65dfSChristoph Hellwig struct nameidata nd; 24216e8341a1SAl Viro int error; 24229850c056SAl Viro struct path path; 24231da177e4SLinus Torvalds int count = 0; 2424d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 242531e6b01fSNick Piggin int flags; 24261f36f774SAl Viro 24271f36f774SAl Viro if (!(open_flag & O_CREAT)) 24281f36f774SAl Viro mode = 0; 24291da177e4SLinus Torvalds 2430b1085ba8SLino Sanfilippo /* Must never be set by userspace */ 2431b1085ba8SLino Sanfilippo open_flag &= ~FMODE_NONOTIFY; 2432b1085ba8SLino Sanfilippo 24336b2f3d1fSChristoph Hellwig /* 24346b2f3d1fSChristoph Hellwig * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only 24356b2f3d1fSChristoph Hellwig * check for O_DSYNC if the need any syncing at all we enforce it's 24366b2f3d1fSChristoph Hellwig * always set instead of having to deal with possibly weird behaviour 24376b2f3d1fSChristoph Hellwig * for malicious applications setting only __O_SYNC. 24386b2f3d1fSChristoph Hellwig */ 24396b2f3d1fSChristoph Hellwig if (open_flag & __O_SYNC) 24406b2f3d1fSChristoph Hellwig open_flag |= O_DSYNC; 24416b2f3d1fSChristoph Hellwig 24426e8341a1SAl Viro if (!acc_mode) 24436d125529SAl Viro acc_mode = MAY_OPEN | ACC_MODE(open_flag); 24441da177e4SLinus Torvalds 2445834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 24464296e2cbSAl Viro if (open_flag & O_TRUNC) 2447834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 2448834f2a4aSTrond Myklebust 24491da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 24501da177e4SLinus Torvalds access from general write access. */ 24514296e2cbSAl Viro if (open_flag & O_APPEND) 24521da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 24531da177e4SLinus Torvalds 245431e6b01fSNick Piggin flags = LOOKUP_OPEN; 245531e6b01fSNick Piggin if (open_flag & O_CREAT) { 245631e6b01fSNick Piggin flags |= LOOKUP_CREATE; 245731e6b01fSNick Piggin if (open_flag & O_EXCL) 245831e6b01fSNick Piggin flags |= LOOKUP_EXCL; 2459654f562cSJ. R. Okajima } 246031e6b01fSNick Piggin if (open_flag & O_DIRECTORY) 246131e6b01fSNick Piggin flags |= LOOKUP_DIRECTORY; 246231e6b01fSNick Piggin if (!(open_flag & O_NOFOLLOW)) 246331e6b01fSNick Piggin flags |= LOOKUP_FOLLOW; 246431e6b01fSNick Piggin 246531e6b01fSNick Piggin filp = get_empty_filp(); 246631e6b01fSNick Piggin if (!filp) 246731e6b01fSNick Piggin return ERR_PTR(-ENFILE); 246831e6b01fSNick Piggin 246931e6b01fSNick Piggin filp->f_flags = open_flag; 247031e6b01fSNick Piggin nd.intent.open.file = filp; 247131e6b01fSNick Piggin nd.intent.open.flags = flag; 247231e6b01fSNick Piggin nd.intent.open.create_mode = mode; 247331e6b01fSNick Piggin 247431e6b01fSNick Piggin if (open_flag & O_CREAT) 247531e6b01fSNick Piggin goto creat; 247631e6b01fSNick Piggin 247731e6b01fSNick Piggin /* !O_CREAT, simple open */ 247831e6b01fSNick Piggin error = do_path_lookup(dfd, pathname, flags, &nd); 247931e6b01fSNick Piggin if (unlikely(error)) 248031e6b01fSNick Piggin goto out_filp; 248131e6b01fSNick Piggin error = -ELOOP; 248231e6b01fSNick Piggin if (!(nd.flags & LOOKUP_FOLLOW)) { 248331e6b01fSNick Piggin if (nd.inode->i_op->follow_link) 248431e6b01fSNick Piggin goto out_path; 248531e6b01fSNick Piggin } 248631e6b01fSNick Piggin error = -ENOTDIR; 248731e6b01fSNick Piggin if (nd.flags & LOOKUP_DIRECTORY) { 248831e6b01fSNick Piggin if (!nd.inode->i_op->lookup) 248931e6b01fSNick Piggin goto out_path; 249031e6b01fSNick Piggin } 249131e6b01fSNick Piggin audit_inode(pathname, nd.path.dentry); 249231e6b01fSNick Piggin filp = finish_open(&nd, open_flag, acc_mode); 24932dab5974SLinus Torvalds release_open_intent(&nd); 249431e6b01fSNick Piggin return filp; 249531e6b01fSNick Piggin 249631e6b01fSNick Piggin creat: 249731e6b01fSNick Piggin /* OK, have to create the file. Find the parent. */ 249831e6b01fSNick Piggin error = path_init_rcu(dfd, pathname, 249931e6b01fSNick Piggin LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd); 250031e6b01fSNick Piggin if (error) 250131e6b01fSNick Piggin goto out_filp; 250231e6b01fSNick Piggin error = path_walk_rcu(pathname, &nd); 250331e6b01fSNick Piggin path_finish_rcu(&nd); 250431e6b01fSNick Piggin if (unlikely(error == -ECHILD || error == -ESTALE)) { 250531e6b01fSNick Piggin /* slower, locked walk */ 250631e6b01fSNick Piggin if (error == -ESTALE) { 250731e6b01fSNick Piggin reval: 250831e6b01fSNick Piggin flags |= LOOKUP_REVAL; 250931e6b01fSNick Piggin } 251031e6b01fSNick Piggin error = path_init(dfd, pathname, 251131e6b01fSNick Piggin LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd); 251231e6b01fSNick Piggin if (error) 251331e6b01fSNick Piggin goto out_filp; 251431e6b01fSNick Piggin 251531e6b01fSNick Piggin error = path_walk_simple(pathname, &nd); 251631e6b01fSNick Piggin } 251731e6b01fSNick Piggin if (unlikely(error)) 251831e6b01fSNick Piggin goto out_filp; 251931e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) 25209b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 25211da177e4SLinus Torvalds 25221da177e4SLinus Torvalds /* 2523a2c36b45SAl Viro * We have the parent and last component. 25241da177e4SLinus Torvalds */ 252531e6b01fSNick Piggin nd.flags = flags; 25263e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 2527806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 25287b9337aaSNick Piggin struct path link = path; 25297b9337aaSNick Piggin struct inode *linki = link.dentry->d_inode; 2530def4af30SAl Viro void *cookie; 2531806b681cSAl Viro error = -ELOOP; 2532db372915SDavid Howells if (!(nd.flags & LOOKUP_FOLLOW)) 25331f36f774SAl Viro goto exit_dput; 25341f36f774SAl Viro if (count++ == 32) 2535806b681cSAl Viro goto exit_dput; 2536806b681cSAl Viro /* 2537806b681cSAl Viro * This is subtle. Instead of calling do_follow_link() we do 2538806b681cSAl Viro * the thing by hands. The reason is that this way we have zero 2539806b681cSAl Viro * link_count and path_walk() (called from ->follow_link) 2540806b681cSAl Viro * honoring LOOKUP_PARENT. After that we have the parent and 2541806b681cSAl Viro * last component, i.e. we are in the same situation as after 2542806b681cSAl Viro * the first path_walk(). Well, almost - if the last component 2543806b681cSAl Viro * is normal we get its copy stored in nd->last.name and we will 2544806b681cSAl Viro * have to putname() it when we are done. Procfs-like symlinks 2545806b681cSAl Viro * just set LAST_BIND. 2546806b681cSAl Viro */ 2547806b681cSAl Viro nd.flags |= LOOKUP_PARENT; 25487b9337aaSNick Piggin error = security_inode_follow_link(link.dentry, &nd); 2549806b681cSAl Viro if (error) 2550806b681cSAl Viro goto exit_dput; 25517b9337aaSNick Piggin error = __do_follow_link(&link, &nd, &cookie); 2552def4af30SAl Viro if (unlikely(error)) { 25537b9337aaSNick Piggin if (!IS_ERR(cookie) && linki->i_op->put_link) 25547b9337aaSNick Piggin linki->i_op->put_link(link.dentry, &nd, cookie); 2555806b681cSAl Viro /* nd.path had been dropped */ 25567b9337aaSNick Piggin nd.path = link; 255731e6b01fSNick Piggin goto out_path; 2558806b681cSAl Viro } 2559806b681cSAl Viro nd.flags &= ~LOOKUP_PARENT; 25603e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 25617b9337aaSNick Piggin if (linki->i_op->put_link) 25627b9337aaSNick Piggin linki->i_op->put_link(link.dentry, &nd, cookie); 25637b9337aaSNick Piggin path_put(&link); 2564806b681cSAl Viro } 256510fa8e62SAl Viro out: 25662a737871SAl Viro if (nd.root.mnt) 25672a737871SAl Viro path_put(&nd.root); 256831e6b01fSNick Piggin if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL)) 256910fa8e62SAl Viro goto reval; 25702dab5974SLinus Torvalds release_open_intent(&nd); 257110fa8e62SAl Viro return filp; 25721da177e4SLinus Torvalds 2573806b681cSAl Viro exit_dput: 2574806b681cSAl Viro path_put_conditional(&path, &nd); 257531e6b01fSNick Piggin out_path: 257631e6b01fSNick Piggin path_put(&nd.path); 257731e6b01fSNick Piggin out_filp: 257810fa8e62SAl Viro filp = ERR_PTR(error); 257910fa8e62SAl Viro goto out; 2580de459215SKirill Korotaev } 25811da177e4SLinus Torvalds 25821da177e4SLinus Torvalds /** 2583a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 2584a70e65dfSChristoph Hellwig * 2585a70e65dfSChristoph Hellwig * @filename: path to open 2586a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 2587a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 2588a70e65dfSChristoph Hellwig * 2589a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 2590a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 2591a70e65dfSChristoph Hellwig * along, nothing to see here.. 2592a70e65dfSChristoph Hellwig */ 2593a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 2594a70e65dfSChristoph Hellwig { 25956e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 2596a70e65dfSChristoph Hellwig } 2597a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 2598a70e65dfSChristoph Hellwig 2599a70e65dfSChristoph Hellwig /** 26001da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 26011da177e4SLinus Torvalds * @nd: nameidata info 26021da177e4SLinus Torvalds * @is_dir: directory flag 26031da177e4SLinus Torvalds * 26041da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 26051da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2606c663e5d8SChristoph Hellwig * 26074ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 26081da177e4SLinus Torvalds */ 26091da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 26101da177e4SLinus Torvalds { 2611c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 26121da177e4SLinus Torvalds 26134ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2614c663e5d8SChristoph Hellwig /* 2615c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2616c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2617c663e5d8SChristoph Hellwig */ 26181da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 26191da177e4SLinus Torvalds goto fail; 26201da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 26213516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2622a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2623c663e5d8SChristoph Hellwig 2624c663e5d8SChristoph Hellwig /* 2625c663e5d8SChristoph Hellwig * Do the final lookup. 2626c663e5d8SChristoph Hellwig */ 262749705b77SChristoph Hellwig dentry = lookup_hash(nd); 26281da177e4SLinus Torvalds if (IS_ERR(dentry)) 26291da177e4SLinus Torvalds goto fail; 2630c663e5d8SChristoph Hellwig 2631e9baf6e5SAl Viro if (dentry->d_inode) 2632e9baf6e5SAl Viro goto eexist; 2633c663e5d8SChristoph Hellwig /* 2634c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2635c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2636c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2637c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2638c663e5d8SChristoph Hellwig */ 2639e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 26401da177e4SLinus Torvalds dput(dentry); 26411da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2642e9baf6e5SAl Viro } 2643e9baf6e5SAl Viro return dentry; 2644e9baf6e5SAl Viro eexist: 2645e9baf6e5SAl Viro dput(dentry); 2646e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 26471da177e4SLinus Torvalds fail: 26481da177e4SLinus Torvalds return dentry; 26491da177e4SLinus Torvalds } 2650f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 26511da177e4SLinus Torvalds 26521da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 26531da177e4SLinus Torvalds { 2654a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26551da177e4SLinus Torvalds 26561da177e4SLinus Torvalds if (error) 26571da177e4SLinus Torvalds return error; 26581da177e4SLinus Torvalds 26591da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 26601da177e4SLinus Torvalds return -EPERM; 26611da177e4SLinus Torvalds 2662acfa4380SAl Viro if (!dir->i_op->mknod) 26631da177e4SLinus Torvalds return -EPERM; 26641da177e4SLinus Torvalds 266508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 266608ce5f16SSerge E. Hallyn if (error) 266708ce5f16SSerge E. Hallyn return error; 266808ce5f16SSerge E. Hallyn 26691da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 26701da177e4SLinus Torvalds if (error) 26711da177e4SLinus Torvalds return error; 26721da177e4SLinus Torvalds 26731da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2674a74574aaSStephen Smalley if (!error) 2675f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26761da177e4SLinus Torvalds return error; 26771da177e4SLinus Torvalds } 26781da177e4SLinus Torvalds 2679463c3197SDave Hansen static int may_mknod(mode_t mode) 2680463c3197SDave Hansen { 2681463c3197SDave Hansen switch (mode & S_IFMT) { 2682463c3197SDave Hansen case S_IFREG: 2683463c3197SDave Hansen case S_IFCHR: 2684463c3197SDave Hansen case S_IFBLK: 2685463c3197SDave Hansen case S_IFIFO: 2686463c3197SDave Hansen case S_IFSOCK: 2687463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2688463c3197SDave Hansen return 0; 2689463c3197SDave Hansen case S_IFDIR: 2690463c3197SDave Hansen return -EPERM; 2691463c3197SDave Hansen default: 2692463c3197SDave Hansen return -EINVAL; 2693463c3197SDave Hansen } 2694463c3197SDave Hansen } 2695463c3197SDave Hansen 26962e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 26972e4d0924SHeiko Carstens unsigned, dev) 26981da177e4SLinus Torvalds { 26992ad94ae6SAl Viro int error; 27001da177e4SLinus Torvalds char *tmp; 27011da177e4SLinus Torvalds struct dentry *dentry; 27021da177e4SLinus Torvalds struct nameidata nd; 27031da177e4SLinus Torvalds 27041da177e4SLinus Torvalds if (S_ISDIR(mode)) 27051da177e4SLinus Torvalds return -EPERM; 27061da177e4SLinus Torvalds 27072ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 27081da177e4SLinus Torvalds if (error) 27092ad94ae6SAl Viro return error; 27102ad94ae6SAl Viro 27111da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2712463c3197SDave Hansen if (IS_ERR(dentry)) { 27131da177e4SLinus Torvalds error = PTR_ERR(dentry); 2714463c3197SDave Hansen goto out_unlock; 2715463c3197SDave Hansen } 27164ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2717ce3b0f8dSAl Viro mode &= ~current_umask(); 2718463c3197SDave Hansen error = may_mknod(mode); 2719463c3197SDave Hansen if (error) 2720463c3197SDave Hansen goto out_dput; 2721463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2722463c3197SDave Hansen if (error) 2723463c3197SDave Hansen goto out_dput; 2724be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2725be6d3e56SKentaro Takeda if (error) 2726be6d3e56SKentaro Takeda goto out_drop_write; 27271da177e4SLinus Torvalds switch (mode & S_IFMT) { 27281da177e4SLinus Torvalds case 0: case S_IFREG: 27294ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 27301da177e4SLinus Torvalds break; 27311da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 27324ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 27331da177e4SLinus Torvalds new_decode_dev(dev)); 27341da177e4SLinus Torvalds break; 27351da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 27364ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 27371da177e4SLinus Torvalds break; 27381da177e4SLinus Torvalds } 2739be6d3e56SKentaro Takeda out_drop_write: 2740463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2741463c3197SDave Hansen out_dput: 27421da177e4SLinus Torvalds dput(dentry); 2743463c3197SDave Hansen out_unlock: 27444ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27451d957f9bSJan Blunck path_put(&nd.path); 27461da177e4SLinus Torvalds putname(tmp); 27471da177e4SLinus Torvalds 27481da177e4SLinus Torvalds return error; 27491da177e4SLinus Torvalds } 27501da177e4SLinus Torvalds 27513480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 27525590ff0dSUlrich Drepper { 27535590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 27545590ff0dSUlrich Drepper } 27555590ff0dSUlrich Drepper 27561da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 27571da177e4SLinus Torvalds { 2758a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27591da177e4SLinus Torvalds 27601da177e4SLinus Torvalds if (error) 27611da177e4SLinus Torvalds return error; 27621da177e4SLinus Torvalds 2763acfa4380SAl Viro if (!dir->i_op->mkdir) 27641da177e4SLinus Torvalds return -EPERM; 27651da177e4SLinus Torvalds 27661da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 27671da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 27681da177e4SLinus Torvalds if (error) 27691da177e4SLinus Torvalds return error; 27701da177e4SLinus Torvalds 27711da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2772a74574aaSStephen Smalley if (!error) 2773f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 27741da177e4SLinus Torvalds return error; 27751da177e4SLinus Torvalds } 27761da177e4SLinus Torvalds 27772e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 27781da177e4SLinus Torvalds { 27791da177e4SLinus Torvalds int error = 0; 27801da177e4SLinus Torvalds char * tmp; 27816902d925SDave Hansen struct dentry *dentry; 27826902d925SDave Hansen struct nameidata nd; 27831da177e4SLinus Torvalds 27842ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 27852ad94ae6SAl Viro if (error) 27866902d925SDave Hansen goto out_err; 27871da177e4SLinus Torvalds 27881da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 27891da177e4SLinus Torvalds error = PTR_ERR(dentry); 27906902d925SDave Hansen if (IS_ERR(dentry)) 27916902d925SDave Hansen goto out_unlock; 27926902d925SDave Hansen 27934ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2794ce3b0f8dSAl Viro mode &= ~current_umask(); 2795463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2796463c3197SDave Hansen if (error) 2797463c3197SDave Hansen goto out_dput; 2798be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2799be6d3e56SKentaro Takeda if (error) 2800be6d3e56SKentaro Takeda goto out_drop_write; 28014ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2802be6d3e56SKentaro Takeda out_drop_write: 2803463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2804463c3197SDave Hansen out_dput: 28051da177e4SLinus Torvalds dput(dentry); 28066902d925SDave Hansen out_unlock: 28074ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28081d957f9bSJan Blunck path_put(&nd.path); 28091da177e4SLinus Torvalds putname(tmp); 28106902d925SDave Hansen out_err: 28111da177e4SLinus Torvalds return error; 28121da177e4SLinus Torvalds } 28131da177e4SLinus Torvalds 28143cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 28155590ff0dSUlrich Drepper { 28165590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 28175590ff0dSUlrich Drepper } 28185590ff0dSUlrich Drepper 28191da177e4SLinus Torvalds /* 28201da177e4SLinus Torvalds * We try to drop the dentry early: we should have 28211da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 28221da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 28231da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 28241da177e4SLinus Torvalds * 28251da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 28261da177e4SLinus Torvalds * do a 28271da177e4SLinus Torvalds * 28281da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 28291da177e4SLinus Torvalds * return -EBUSY; 28301da177e4SLinus Torvalds * 28311da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 28321da177e4SLinus Torvalds * that is still in use by something else.. 28331da177e4SLinus Torvalds */ 28341da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 28351da177e4SLinus Torvalds { 28361da177e4SLinus Torvalds dget(dentry); 28371da177e4SLinus Torvalds shrink_dcache_parent(dentry); 28381da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2839b7ab39f6SNick Piggin if (dentry->d_count == 2) 28401da177e4SLinus Torvalds __d_drop(dentry); 28411da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 28421da177e4SLinus Torvalds } 28431da177e4SLinus Torvalds 28441da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 28451da177e4SLinus Torvalds { 28461da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 28471da177e4SLinus Torvalds 28481da177e4SLinus Torvalds if (error) 28491da177e4SLinus Torvalds return error; 28501da177e4SLinus Torvalds 2851acfa4380SAl Viro if (!dir->i_op->rmdir) 28521da177e4SLinus Torvalds return -EPERM; 28531da177e4SLinus Torvalds 28541b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 28551da177e4SLinus Torvalds dentry_unhash(dentry); 28561da177e4SLinus Torvalds if (d_mountpoint(dentry)) 28571da177e4SLinus Torvalds error = -EBUSY; 28581da177e4SLinus Torvalds else { 28591da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 28601da177e4SLinus Torvalds if (!error) { 28611da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2862d83c49f3SAl Viro if (!error) { 28631da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2864d83c49f3SAl Viro dont_mount(dentry); 2865d83c49f3SAl Viro } 28661da177e4SLinus Torvalds } 28671da177e4SLinus Torvalds } 28681b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 28691da177e4SLinus Torvalds if (!error) { 28701da177e4SLinus Torvalds d_delete(dentry); 28711da177e4SLinus Torvalds } 28721da177e4SLinus Torvalds dput(dentry); 28731da177e4SLinus Torvalds 28741da177e4SLinus Torvalds return error; 28751da177e4SLinus Torvalds } 28761da177e4SLinus Torvalds 28775590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 28781da177e4SLinus Torvalds { 28791da177e4SLinus Torvalds int error = 0; 28801da177e4SLinus Torvalds char * name; 28811da177e4SLinus Torvalds struct dentry *dentry; 28821da177e4SLinus Torvalds struct nameidata nd; 28831da177e4SLinus Torvalds 28842ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 28851da177e4SLinus Torvalds if (error) 28862ad94ae6SAl Viro return error; 28871da177e4SLinus Torvalds 28881da177e4SLinus Torvalds switch(nd.last_type) { 28891da177e4SLinus Torvalds case LAST_DOTDOT: 28901da177e4SLinus Torvalds error = -ENOTEMPTY; 28911da177e4SLinus Torvalds goto exit1; 28921da177e4SLinus Torvalds case LAST_DOT: 28931da177e4SLinus Torvalds error = -EINVAL; 28941da177e4SLinus Torvalds goto exit1; 28951da177e4SLinus Torvalds case LAST_ROOT: 28961da177e4SLinus Torvalds error = -EBUSY; 28971da177e4SLinus Torvalds goto exit1; 28981da177e4SLinus Torvalds } 28990612d9fbSOGAWA Hirofumi 29000612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 29010612d9fbSOGAWA Hirofumi 29024ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 290349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 29041da177e4SLinus Torvalds error = PTR_ERR(dentry); 29056902d925SDave Hansen if (IS_ERR(dentry)) 29066902d925SDave Hansen goto exit2; 29070622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 29080622753bSDave Hansen if (error) 29090622753bSDave Hansen goto exit3; 2910be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2911be6d3e56SKentaro Takeda if (error) 2912be6d3e56SKentaro Takeda goto exit4; 29134ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2914be6d3e56SKentaro Takeda exit4: 29150622753bSDave Hansen mnt_drop_write(nd.path.mnt); 29160622753bSDave Hansen exit3: 29171da177e4SLinus Torvalds dput(dentry); 29186902d925SDave Hansen exit2: 29194ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29201da177e4SLinus Torvalds exit1: 29211d957f9bSJan Blunck path_put(&nd.path); 29221da177e4SLinus Torvalds putname(name); 29231da177e4SLinus Torvalds return error; 29241da177e4SLinus Torvalds } 29251da177e4SLinus Torvalds 29263cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 29275590ff0dSUlrich Drepper { 29285590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 29295590ff0dSUlrich Drepper } 29305590ff0dSUlrich Drepper 29311da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 29321da177e4SLinus Torvalds { 29331da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 29341da177e4SLinus Torvalds 29351da177e4SLinus Torvalds if (error) 29361da177e4SLinus Torvalds return error; 29371da177e4SLinus Torvalds 2938acfa4380SAl Viro if (!dir->i_op->unlink) 29391da177e4SLinus Torvalds return -EPERM; 29401da177e4SLinus Torvalds 29411b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 29421da177e4SLinus Torvalds if (d_mountpoint(dentry)) 29431da177e4SLinus Torvalds error = -EBUSY; 29441da177e4SLinus Torvalds else { 29451da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2946bec1052eSAl Viro if (!error) { 29471da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2948bec1052eSAl Viro if (!error) 2949d83c49f3SAl Viro dont_mount(dentry); 2950bec1052eSAl Viro } 29511da177e4SLinus Torvalds } 29521b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 29531da177e4SLinus Torvalds 29541da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 29551da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2956ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 29571da177e4SLinus Torvalds d_delete(dentry); 29581da177e4SLinus Torvalds } 29590eeca283SRobert Love 29601da177e4SLinus Torvalds return error; 29611da177e4SLinus Torvalds } 29621da177e4SLinus Torvalds 29631da177e4SLinus Torvalds /* 29641da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 29651b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 29661da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 29671da177e4SLinus Torvalds * while waiting on the I/O. 29681da177e4SLinus Torvalds */ 29695590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 29701da177e4SLinus Torvalds { 29712ad94ae6SAl Viro int error; 29721da177e4SLinus Torvalds char *name; 29731da177e4SLinus Torvalds struct dentry *dentry; 29741da177e4SLinus Torvalds struct nameidata nd; 29751da177e4SLinus Torvalds struct inode *inode = NULL; 29761da177e4SLinus Torvalds 29772ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 29781da177e4SLinus Torvalds if (error) 29792ad94ae6SAl Viro return error; 29802ad94ae6SAl Viro 29811da177e4SLinus Torvalds error = -EISDIR; 29821da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 29831da177e4SLinus Torvalds goto exit1; 29840612d9fbSOGAWA Hirofumi 29850612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 29860612d9fbSOGAWA Hirofumi 29874ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 298849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 29891da177e4SLinus Torvalds error = PTR_ERR(dentry); 29901da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 29911da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 29921da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 29931da177e4SLinus Torvalds goto slashes; 29941da177e4SLinus Torvalds inode = dentry->d_inode; 29951da177e4SLinus Torvalds if (inode) 29967de9c6eeSAl Viro ihold(inode); 29970622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 29980622753bSDave Hansen if (error) 29990622753bSDave Hansen goto exit2; 3000be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3001be6d3e56SKentaro Takeda if (error) 3002be6d3e56SKentaro Takeda goto exit3; 30034ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 3004be6d3e56SKentaro Takeda exit3: 30050622753bSDave Hansen mnt_drop_write(nd.path.mnt); 30061da177e4SLinus Torvalds exit2: 30071da177e4SLinus Torvalds dput(dentry); 30081da177e4SLinus Torvalds } 30094ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 30101da177e4SLinus Torvalds if (inode) 30111da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 30121da177e4SLinus Torvalds exit1: 30131d957f9bSJan Blunck path_put(&nd.path); 30141da177e4SLinus Torvalds putname(name); 30151da177e4SLinus Torvalds return error; 30161da177e4SLinus Torvalds 30171da177e4SLinus Torvalds slashes: 30181da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 30191da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 30201da177e4SLinus Torvalds goto exit2; 30211da177e4SLinus Torvalds } 30221da177e4SLinus Torvalds 30232e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 30245590ff0dSUlrich Drepper { 30255590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 30265590ff0dSUlrich Drepper return -EINVAL; 30275590ff0dSUlrich Drepper 30285590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 30295590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 30305590ff0dSUlrich Drepper 30315590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 30325590ff0dSUlrich Drepper } 30335590ff0dSUlrich Drepper 30343480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 30355590ff0dSUlrich Drepper { 30365590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 30375590ff0dSUlrich Drepper } 30385590ff0dSUlrich Drepper 3039db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 30401da177e4SLinus Torvalds { 3041a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30421da177e4SLinus Torvalds 30431da177e4SLinus Torvalds if (error) 30441da177e4SLinus Torvalds return error; 30451da177e4SLinus Torvalds 3046acfa4380SAl Viro if (!dir->i_op->symlink) 30471da177e4SLinus Torvalds return -EPERM; 30481da177e4SLinus Torvalds 30491da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 30501da177e4SLinus Torvalds if (error) 30511da177e4SLinus Torvalds return error; 30521da177e4SLinus Torvalds 30531da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3054a74574aaSStephen Smalley if (!error) 3055f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30561da177e4SLinus Torvalds return error; 30571da177e4SLinus Torvalds } 30581da177e4SLinus Torvalds 30592e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 30602e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 30611da177e4SLinus Torvalds { 30622ad94ae6SAl Viro int error; 30631da177e4SLinus Torvalds char *from; 30641da177e4SLinus Torvalds char *to; 30656902d925SDave Hansen struct dentry *dentry; 30666902d925SDave Hansen struct nameidata nd; 30671da177e4SLinus Torvalds 30681da177e4SLinus Torvalds from = getname(oldname); 30691da177e4SLinus Torvalds if (IS_ERR(from)) 30701da177e4SLinus Torvalds return PTR_ERR(from); 30712ad94ae6SAl Viro 30722ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 30732ad94ae6SAl Viro if (error) 30746902d925SDave Hansen goto out_putname; 30751da177e4SLinus Torvalds 30761da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 30771da177e4SLinus Torvalds error = PTR_ERR(dentry); 30786902d925SDave Hansen if (IS_ERR(dentry)) 30796902d925SDave Hansen goto out_unlock; 30806902d925SDave Hansen 308175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 308275c3f29dSDave Hansen if (error) 308375c3f29dSDave Hansen goto out_dput; 3084be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 3085be6d3e56SKentaro Takeda if (error) 3086be6d3e56SKentaro Takeda goto out_drop_write; 3087db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 3088be6d3e56SKentaro Takeda out_drop_write: 308975c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 309075c3f29dSDave Hansen out_dput: 30911da177e4SLinus Torvalds dput(dentry); 30926902d925SDave Hansen out_unlock: 30934ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 30941d957f9bSJan Blunck path_put(&nd.path); 30951da177e4SLinus Torvalds putname(to); 30966902d925SDave Hansen out_putname: 30971da177e4SLinus Torvalds putname(from); 30981da177e4SLinus Torvalds return error; 30991da177e4SLinus Torvalds } 31001da177e4SLinus Torvalds 31013480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 31025590ff0dSUlrich Drepper { 31035590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 31045590ff0dSUlrich Drepper } 31055590ff0dSUlrich Drepper 31061da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 31071da177e4SLinus Torvalds { 31081da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 31091da177e4SLinus Torvalds int error; 31101da177e4SLinus Torvalds 31111da177e4SLinus Torvalds if (!inode) 31121da177e4SLinus Torvalds return -ENOENT; 31131da177e4SLinus Torvalds 3114a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 31151da177e4SLinus Torvalds if (error) 31161da177e4SLinus Torvalds return error; 31171da177e4SLinus Torvalds 31181da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 31191da177e4SLinus Torvalds return -EXDEV; 31201da177e4SLinus Torvalds 31211da177e4SLinus Torvalds /* 31221da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 31231da177e4SLinus Torvalds */ 31241da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 31251da177e4SLinus Torvalds return -EPERM; 3126acfa4380SAl Viro if (!dir->i_op->link) 31271da177e4SLinus Torvalds return -EPERM; 31287e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 31291da177e4SLinus Torvalds return -EPERM; 31301da177e4SLinus Torvalds 31311da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 31321da177e4SLinus Torvalds if (error) 31331da177e4SLinus Torvalds return error; 31341da177e4SLinus Torvalds 31357e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 31361da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 31377e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3138e31e14ecSStephen Smalley if (!error) 31397e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 31401da177e4SLinus Torvalds return error; 31411da177e4SLinus Torvalds } 31421da177e4SLinus Torvalds 31431da177e4SLinus Torvalds /* 31441da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 31451da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 31461da177e4SLinus Torvalds * newname. --KAB 31471da177e4SLinus Torvalds * 31481da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 31491da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 31501da177e4SLinus Torvalds * and other special files. --ADM 31511da177e4SLinus Torvalds */ 31522e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 31532e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 31541da177e4SLinus Torvalds { 31551da177e4SLinus Torvalds struct dentry *new_dentry; 31562d8f3038SAl Viro struct nameidata nd; 31572d8f3038SAl Viro struct path old_path; 31581da177e4SLinus Torvalds int error; 31591da177e4SLinus Torvalds char *to; 31601da177e4SLinus Torvalds 316145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 3162c04030e1SUlrich Drepper return -EINVAL; 3163c04030e1SUlrich Drepper 31642d8f3038SAl Viro error = user_path_at(olddfd, oldname, 316545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 31662d8f3038SAl Viro &old_path); 31671da177e4SLinus Torvalds if (error) 31682ad94ae6SAl Viro return error; 31692ad94ae6SAl Viro 31702ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 31711da177e4SLinus Torvalds if (error) 31721da177e4SLinus Torvalds goto out; 31731da177e4SLinus Torvalds error = -EXDEV; 31742d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 31751da177e4SLinus Torvalds goto out_release; 31761da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 31771da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31786902d925SDave Hansen if (IS_ERR(new_dentry)) 31796902d925SDave Hansen goto out_unlock; 318075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 318175c3f29dSDave Hansen if (error) 318275c3f29dSDave Hansen goto out_dput; 3183be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 3184be6d3e56SKentaro Takeda if (error) 3185be6d3e56SKentaro Takeda goto out_drop_write; 31862d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 3187be6d3e56SKentaro Takeda out_drop_write: 318875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 318975c3f29dSDave Hansen out_dput: 31901da177e4SLinus Torvalds dput(new_dentry); 31916902d925SDave Hansen out_unlock: 31924ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 31931da177e4SLinus Torvalds out_release: 31941d957f9bSJan Blunck path_put(&nd.path); 31952ad94ae6SAl Viro putname(to); 31961da177e4SLinus Torvalds out: 31972d8f3038SAl Viro path_put(&old_path); 31981da177e4SLinus Torvalds 31991da177e4SLinus Torvalds return error; 32001da177e4SLinus Torvalds } 32011da177e4SLinus Torvalds 32023480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 32035590ff0dSUlrich Drepper { 3204c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 32055590ff0dSUlrich Drepper } 32065590ff0dSUlrich Drepper 32071da177e4SLinus Torvalds /* 32081da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 32091da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 32101da177e4SLinus Torvalds * Problems: 32111da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 32121da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 32131da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3214a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 32151da177e4SLinus Torvalds * story. 32161da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 32171b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 32181da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 32191da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3220a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 32211da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 32221da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 32231da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3224a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 32251da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 32261da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 32271da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 32281da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 32291da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 32301da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 32311da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 32321da177e4SLinus Torvalds * trick as in rmdir(). 32331da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 32341b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 32351da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3236c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 32371da177e4SLinus Torvalds * locking]. 32381da177e4SLinus Torvalds */ 323975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 32401da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32411da177e4SLinus Torvalds { 32421da177e4SLinus Torvalds int error = 0; 32431da177e4SLinus Torvalds struct inode *target; 32441da177e4SLinus Torvalds 32451da177e4SLinus Torvalds /* 32461da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 32471da177e4SLinus Torvalds * we'll need to flip '..'. 32481da177e4SLinus Torvalds */ 32491da177e4SLinus Torvalds if (new_dir != old_dir) { 3250f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 32511da177e4SLinus Torvalds if (error) 32521da177e4SLinus Torvalds return error; 32531da177e4SLinus Torvalds } 32541da177e4SLinus Torvalds 32551da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 32561da177e4SLinus Torvalds if (error) 32571da177e4SLinus Torvalds return error; 32581da177e4SLinus Torvalds 32591da177e4SLinus Torvalds target = new_dentry->d_inode; 3260d83c49f3SAl Viro if (target) 32611b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 32621da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 32631da177e4SLinus Torvalds error = -EBUSY; 3264d83c49f3SAl Viro else { 3265d83c49f3SAl Viro if (target) 3266d83c49f3SAl Viro dentry_unhash(new_dentry); 32671da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3268d83c49f3SAl Viro } 32691da177e4SLinus Torvalds if (target) { 3270d83c49f3SAl Viro if (!error) { 32711da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3272d83c49f3SAl Viro dont_mount(new_dentry); 3273d83c49f3SAl Viro } 32741b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 32751da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 32761da177e4SLinus Torvalds d_rehash(new_dentry); 32771da177e4SLinus Torvalds dput(new_dentry); 32781da177e4SLinus Torvalds } 3279e31e14ecSStephen Smalley if (!error) 3280349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 32811da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 32821da177e4SLinus Torvalds return error; 32831da177e4SLinus Torvalds } 32841da177e4SLinus Torvalds 328575c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 32861da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32871da177e4SLinus Torvalds { 32881da177e4SLinus Torvalds struct inode *target; 32891da177e4SLinus Torvalds int error; 32901da177e4SLinus Torvalds 32911da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 32921da177e4SLinus Torvalds if (error) 32931da177e4SLinus Torvalds return error; 32941da177e4SLinus Torvalds 32951da177e4SLinus Torvalds dget(new_dentry); 32961da177e4SLinus Torvalds target = new_dentry->d_inode; 32971da177e4SLinus Torvalds if (target) 32981b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 32991da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 33001da177e4SLinus Torvalds error = -EBUSY; 33011da177e4SLinus Torvalds else 33021da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 33031da177e4SLinus Torvalds if (!error) { 3304bec1052eSAl Viro if (target) 3305d83c49f3SAl Viro dont_mount(new_dentry); 3306349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 33071da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 33081da177e4SLinus Torvalds } 33091da177e4SLinus Torvalds if (target) 33101b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 33111da177e4SLinus Torvalds dput(new_dentry); 33121da177e4SLinus Torvalds return error; 33131da177e4SLinus Torvalds } 33141da177e4SLinus Torvalds 33151da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 33161da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 33171da177e4SLinus Torvalds { 33181da177e4SLinus Torvalds int error; 33191da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 332059b0df21SEric Paris const unsigned char *old_name; 33211da177e4SLinus Torvalds 33221da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 33231da177e4SLinus Torvalds return 0; 33241da177e4SLinus Torvalds 33251da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 33261da177e4SLinus Torvalds if (error) 33271da177e4SLinus Torvalds return error; 33281da177e4SLinus Torvalds 33291da177e4SLinus Torvalds if (!new_dentry->d_inode) 3330a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 33311da177e4SLinus Torvalds else 33321da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 33331da177e4SLinus Torvalds if (error) 33341da177e4SLinus Torvalds return error; 33351da177e4SLinus Torvalds 3336acfa4380SAl Viro if (!old_dir->i_op->rename) 33371da177e4SLinus Torvalds return -EPERM; 33381da177e4SLinus Torvalds 33390eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 33400eeca283SRobert Love 33411da177e4SLinus Torvalds if (is_dir) 33421da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 33431da177e4SLinus Torvalds else 33441da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3345123df294SAl Viro if (!error) 3346123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 33475a190ae6SAl Viro new_dentry->d_inode, old_dentry); 33480eeca283SRobert Love fsnotify_oldname_free(old_name); 33490eeca283SRobert Love 33501da177e4SLinus Torvalds return error; 33511da177e4SLinus Torvalds } 33521da177e4SLinus Torvalds 33532e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 33542e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 33551da177e4SLinus Torvalds { 33561da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 33571da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 33581da177e4SLinus Torvalds struct dentry *trap; 33591da177e4SLinus Torvalds struct nameidata oldnd, newnd; 33602ad94ae6SAl Viro char *from; 33612ad94ae6SAl Viro char *to; 33622ad94ae6SAl Viro int error; 33631da177e4SLinus Torvalds 33642ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 33651da177e4SLinus Torvalds if (error) 33661da177e4SLinus Torvalds goto exit; 33671da177e4SLinus Torvalds 33682ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 33691da177e4SLinus Torvalds if (error) 33701da177e4SLinus Torvalds goto exit1; 33711da177e4SLinus Torvalds 33721da177e4SLinus Torvalds error = -EXDEV; 33734ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 33741da177e4SLinus Torvalds goto exit2; 33751da177e4SLinus Torvalds 33764ac91378SJan Blunck old_dir = oldnd.path.dentry; 33771da177e4SLinus Torvalds error = -EBUSY; 33781da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 33791da177e4SLinus Torvalds goto exit2; 33801da177e4SLinus Torvalds 33814ac91378SJan Blunck new_dir = newnd.path.dentry; 33821da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 33831da177e4SLinus Torvalds goto exit2; 33841da177e4SLinus Torvalds 33850612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 33860612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 33874e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 33880612d9fbSOGAWA Hirofumi 33891da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 33901da177e4SLinus Torvalds 339149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 33921da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 33931da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 33941da177e4SLinus Torvalds goto exit3; 33951da177e4SLinus Torvalds /* source must exist */ 33961da177e4SLinus Torvalds error = -ENOENT; 33971da177e4SLinus Torvalds if (!old_dentry->d_inode) 33981da177e4SLinus Torvalds goto exit4; 33991da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 34001da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 34011da177e4SLinus Torvalds error = -ENOTDIR; 34021da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 34031da177e4SLinus Torvalds goto exit4; 34041da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 34051da177e4SLinus Torvalds goto exit4; 34061da177e4SLinus Torvalds } 34071da177e4SLinus Torvalds /* source should not be ancestor of target */ 34081da177e4SLinus Torvalds error = -EINVAL; 34091da177e4SLinus Torvalds if (old_dentry == trap) 34101da177e4SLinus Torvalds goto exit4; 341149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 34121da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 34131da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 34141da177e4SLinus Torvalds goto exit4; 34151da177e4SLinus Torvalds /* target should not be an ancestor of source */ 34161da177e4SLinus Torvalds error = -ENOTEMPTY; 34171da177e4SLinus Torvalds if (new_dentry == trap) 34181da177e4SLinus Torvalds goto exit5; 34191da177e4SLinus Torvalds 34209079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 34219079b1ebSDave Hansen if (error) 34229079b1ebSDave Hansen goto exit5; 3423be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3424be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3425be6d3e56SKentaro Takeda if (error) 3426be6d3e56SKentaro Takeda goto exit6; 34271da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 34281da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3429be6d3e56SKentaro Takeda exit6: 34309079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 34311da177e4SLinus Torvalds exit5: 34321da177e4SLinus Torvalds dput(new_dentry); 34331da177e4SLinus Torvalds exit4: 34341da177e4SLinus Torvalds dput(old_dentry); 34351da177e4SLinus Torvalds exit3: 34361da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 34371da177e4SLinus Torvalds exit2: 34381d957f9bSJan Blunck path_put(&newnd.path); 34392ad94ae6SAl Viro putname(to); 34401da177e4SLinus Torvalds exit1: 34411d957f9bSJan Blunck path_put(&oldnd.path); 34421da177e4SLinus Torvalds putname(from); 34432ad94ae6SAl Viro exit: 34441da177e4SLinus Torvalds return error; 34451da177e4SLinus Torvalds } 34461da177e4SLinus Torvalds 3447a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 34485590ff0dSUlrich Drepper { 34495590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 34505590ff0dSUlrich Drepper } 34515590ff0dSUlrich Drepper 34521da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 34531da177e4SLinus Torvalds { 34541da177e4SLinus Torvalds int len; 34551da177e4SLinus Torvalds 34561da177e4SLinus Torvalds len = PTR_ERR(link); 34571da177e4SLinus Torvalds if (IS_ERR(link)) 34581da177e4SLinus Torvalds goto out; 34591da177e4SLinus Torvalds 34601da177e4SLinus Torvalds len = strlen(link); 34611da177e4SLinus Torvalds if (len > (unsigned) buflen) 34621da177e4SLinus Torvalds len = buflen; 34631da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 34641da177e4SLinus Torvalds len = -EFAULT; 34651da177e4SLinus Torvalds out: 34661da177e4SLinus Torvalds return len; 34671da177e4SLinus Torvalds } 34681da177e4SLinus Torvalds 34691da177e4SLinus Torvalds /* 34701da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 34711da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 34721da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 34731da177e4SLinus Torvalds */ 34741da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 34751da177e4SLinus Torvalds { 34761da177e4SLinus Torvalds struct nameidata nd; 3477cc314eefSLinus Torvalds void *cookie; 3478694a1764SMarcin Slusarz int res; 3479cc314eefSLinus Torvalds 34801da177e4SLinus Torvalds nd.depth = 0; 3481cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3482694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3483694a1764SMarcin Slusarz return PTR_ERR(cookie); 3484694a1764SMarcin Slusarz 3485694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 34861da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3487cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3488694a1764SMarcin Slusarz return res; 34891da177e4SLinus Torvalds } 34901da177e4SLinus Torvalds 34911da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 34921da177e4SLinus Torvalds { 34931da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 34941da177e4SLinus Torvalds } 34951da177e4SLinus Torvalds 34961da177e4SLinus Torvalds /* get the link contents into pagecache */ 34971da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 34981da177e4SLinus Torvalds { 3499ebd09abbSDuane Griffin char *kaddr; 35001da177e4SLinus Torvalds struct page *page; 35011da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3502090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 35031da177e4SLinus Torvalds if (IS_ERR(page)) 35046fe6900eSNick Piggin return (char*)page; 35051da177e4SLinus Torvalds *ppage = page; 3506ebd09abbSDuane Griffin kaddr = kmap(page); 3507ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3508ebd09abbSDuane Griffin return kaddr; 35091da177e4SLinus Torvalds } 35101da177e4SLinus Torvalds 35111da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 35121da177e4SLinus Torvalds { 35131da177e4SLinus Torvalds struct page *page = NULL; 35141da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 35151da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 35161da177e4SLinus Torvalds if (page) { 35171da177e4SLinus Torvalds kunmap(page); 35181da177e4SLinus Torvalds page_cache_release(page); 35191da177e4SLinus Torvalds } 35201da177e4SLinus Torvalds return res; 35211da177e4SLinus Torvalds } 35221da177e4SLinus Torvalds 3523cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 35241da177e4SLinus Torvalds { 3525cc314eefSLinus Torvalds struct page *page = NULL; 35261da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3527cc314eefSLinus Torvalds return page; 35281da177e4SLinus Torvalds } 35291da177e4SLinus Torvalds 3530cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 35311da177e4SLinus Torvalds { 3532cc314eefSLinus Torvalds struct page *page = cookie; 3533cc314eefSLinus Torvalds 3534cc314eefSLinus Torvalds if (page) { 35351da177e4SLinus Torvalds kunmap(page); 35361da177e4SLinus Torvalds page_cache_release(page); 35371da177e4SLinus Torvalds } 35381da177e4SLinus Torvalds } 35391da177e4SLinus Torvalds 354054566b2cSNick Piggin /* 354154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 354254566b2cSNick Piggin */ 354354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 35441da177e4SLinus Torvalds { 35451da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 35460adb25d2SKirill Korotaev struct page *page; 3547afddba49SNick Piggin void *fsdata; 3548beb497abSDmitriy Monakhov int err; 35491da177e4SLinus Torvalds char *kaddr; 355054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 355154566b2cSNick Piggin if (nofs) 355254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 35531da177e4SLinus Torvalds 35547e53cac4SNeilBrown retry: 3555afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 355654566b2cSNick Piggin flags, &page, &fsdata); 35571da177e4SLinus Torvalds if (err) 3558afddba49SNick Piggin goto fail; 3559afddba49SNick Piggin 35601da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 35611da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 35621da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3563afddba49SNick Piggin 3564afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3565afddba49SNick Piggin page, fsdata); 35661da177e4SLinus Torvalds if (err < 0) 35671da177e4SLinus Torvalds goto fail; 3568afddba49SNick Piggin if (err < len-1) 3569afddba49SNick Piggin goto retry; 3570afddba49SNick Piggin 35711da177e4SLinus Torvalds mark_inode_dirty(inode); 35721da177e4SLinus Torvalds return 0; 35731da177e4SLinus Torvalds fail: 35741da177e4SLinus Torvalds return err; 35751da177e4SLinus Torvalds } 35761da177e4SLinus Torvalds 35770adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 35780adb25d2SKirill Korotaev { 35790adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 358054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 35810adb25d2SKirill Korotaev } 35820adb25d2SKirill Korotaev 358392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 35841da177e4SLinus Torvalds .readlink = generic_readlink, 35851da177e4SLinus Torvalds .follow_link = page_follow_link_light, 35861da177e4SLinus Torvalds .put_link = page_put_link, 35871da177e4SLinus Torvalds }; 35881da177e4SLinus Torvalds 35892d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3590cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 35911da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 35921da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 35931da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 35941da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 35951da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 35961da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 35971da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 35981da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 35991da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 36000adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 36011da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 36021da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 36031da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 3604d1811465SAl Viro EXPORT_SYMBOL(kern_path); 360516f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3606f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 36078c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 36081da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 36091da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 36101da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 36111da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 36121da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 36131da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 36141da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 36151da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 36161da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 36171da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 36181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 36191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 36201da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 36211da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3622