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/quotaops.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.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> 341da177e4SLinus Torvalds #include <asm/uaccess.h> 351da177e4SLinus Torvalds 361da177e4SLinus Torvalds #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 391da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 401da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 411da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 421da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 431da177e4SLinus Torvalds * 441da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 451da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 461da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 471da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 481da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 491da177e4SLinus Torvalds * the special cases of the former code. 501da177e4SLinus Torvalds * 511da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 521da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 531da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 541da177e4SLinus Torvalds * 551da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 561da177e4SLinus Torvalds * resolution to correspond with current state of the code. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 591da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 601da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 611da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 621da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 631da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 641da177e4SLinus Torvalds */ 651da177e4SLinus Torvalds 661da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 671da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 681da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 691da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 701da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 711da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 721da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 731da177e4SLinus Torvalds * 741da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 751da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 761da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 771da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 781da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 791da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 801da177e4SLinus Torvalds * and in the old Linux semantics. 811da177e4SLinus Torvalds */ 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 841da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 851da177e4SLinus Torvalds * 861da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 871da177e4SLinus Torvalds */ 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 901da177e4SLinus Torvalds * inside the path - always follow. 911da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 921da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 931da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 941da177e4SLinus Torvalds * otherwise - don't follow. 951da177e4SLinus Torvalds * (applied in that order). 961da177e4SLinus Torvalds * 971da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 981da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 991da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1001da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1011da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1021da177e4SLinus Torvalds */ 1031da177e4SLinus Torvalds /* 1041da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 105a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1061da177e4SLinus Torvalds * any extra contention... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds 109a02f76c3SAl Viro static int __link_path_walk(const char *name, struct nameidata *nd); 110c4a7808fSJosef 'Jeff' Sipek 1111da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1121da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1131da177e4SLinus Torvalds * kernel data space before using them.. 1141da177e4SLinus Torvalds * 1151da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1161da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1171da177e4SLinus Torvalds */ 118858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1191da177e4SLinus Torvalds { 1201da177e4SLinus Torvalds int retval; 1211da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1221da177e4SLinus Torvalds 1231da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1241da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1251da177e4SLinus Torvalds return -EFAULT; 1261da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1271da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1311da177e4SLinus Torvalds if (retval > 0) { 1321da177e4SLinus Torvalds if (retval < len) 1331da177e4SLinus Torvalds return 0; 1341da177e4SLinus Torvalds return -ENAMETOOLONG; 1351da177e4SLinus Torvalds } else if (!retval) 1361da177e4SLinus Torvalds retval = -ENOENT; 1371da177e4SLinus Torvalds return retval; 1381da177e4SLinus Torvalds } 1391da177e4SLinus Torvalds 1401da177e4SLinus Torvalds char * getname(const char __user * filename) 1411da177e4SLinus Torvalds { 1421da177e4SLinus Torvalds char *tmp, *result; 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1451da177e4SLinus Torvalds tmp = __getname(); 1461da177e4SLinus Torvalds if (tmp) { 1471da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds result = tmp; 1501da177e4SLinus Torvalds if (retval < 0) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds audit_getname(result); 1561da177e4SLinus Torvalds return result; 1571da177e4SLinus Torvalds } 1581da177e4SLinus Torvalds 1591da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1601da177e4SLinus Torvalds void putname(const char *name) 1611da177e4SLinus Torvalds { 1625ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1631da177e4SLinus Torvalds audit_putname(name); 1641da177e4SLinus Torvalds else 1651da177e4SLinus Torvalds __putname(name); 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1681da177e4SLinus Torvalds #endif 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /** 1721da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 1731da177e4SLinus Torvalds * @inode: inode to check access rights for 1741da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 1751da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 1761da177e4SLinus Torvalds * 1771da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 1781da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 1791da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 1801da177e4SLinus Torvalds * are used for other things.. 1811da177e4SLinus Torvalds */ 1821da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 1831da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1841da177e4SLinus Torvalds { 1851da177e4SLinus Torvalds umode_t mode = inode->i_mode; 1861da177e4SLinus Torvalds 187e6305c43SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 188e6305c43SAl Viro 1891da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 1901da177e4SLinus Torvalds mode >>= 6; 1911da177e4SLinus Torvalds else { 1921da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1931da177e4SLinus Torvalds int error = check_acl(inode, mask); 1941da177e4SLinus Torvalds if (error == -EACCES) 1951da177e4SLinus Torvalds goto check_capabilities; 1961da177e4SLinus Torvalds else if (error != -EAGAIN) 1971da177e4SLinus Torvalds return error; 1981da177e4SLinus Torvalds } 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 2011da177e4SLinus Torvalds mode >>= 3; 2021da177e4SLinus Torvalds } 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds /* 2051da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2061da177e4SLinus Torvalds */ 207e6305c43SAl Viro if ((mask & ~mode) == 0) 2081da177e4SLinus Torvalds return 0; 2091da177e4SLinus Torvalds 2101da177e4SLinus Torvalds check_capabilities: 2111da177e4SLinus Torvalds /* 2121da177e4SLinus Torvalds * Read/write DACs are always overridable. 2131da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2141da177e4SLinus Torvalds */ 2151da177e4SLinus Torvalds if (!(mask & MAY_EXEC) || 2161da177e4SLinus Torvalds (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode)) 2171da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2181da177e4SLinus Torvalds return 0; 2191da177e4SLinus Torvalds 2201da177e4SLinus Torvalds /* 2211da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2221da177e4SLinus Torvalds */ 2231da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2241da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2251da177e4SLinus Torvalds return 0; 2261da177e4SLinus Torvalds 2271da177e4SLinus Torvalds return -EACCES; 2281da177e4SLinus Torvalds } 2291da177e4SLinus Torvalds 230f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2311da177e4SLinus Torvalds { 232e6305c43SAl Viro int retval; 2331da177e4SLinus Torvalds 2341da177e4SLinus Torvalds if (mask & MAY_WRITE) { 23522590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2361da177e4SLinus Torvalds 2371da177e4SLinus Torvalds /* 2381da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2391da177e4SLinus Torvalds */ 2401da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2411da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2421da177e4SLinus Torvalds return -EROFS; 2431da177e4SLinus Torvalds 2441da177e4SLinus Torvalds /* 2451da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2461da177e4SLinus Torvalds */ 2471da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2481da177e4SLinus Torvalds return -EACCES; 2491da177e4SLinus Torvalds } 2501da177e4SLinus Torvalds 2511da177e4SLinus Torvalds /* Ordinary permission routines do not understand MAY_APPEND. */ 25222590e41SMiklos Szeredi if (inode->i_op && inode->i_op->permission) { 253b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 25422590e41SMiklos Szeredi if (!retval) { 25522590e41SMiklos Szeredi /* 25622590e41SMiklos Szeredi * Exec permission on a regular file is denied if none 25722590e41SMiklos Szeredi * of the execute bits are set. 25822590e41SMiklos Szeredi * 25922590e41SMiklos Szeredi * This check should be done by the ->permission() 26022590e41SMiklos Szeredi * method. 26122590e41SMiklos Szeredi */ 26222590e41SMiklos Szeredi if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) && 26322590e41SMiklos Szeredi !(inode->i_mode & S_IXUGO)) 26422590e41SMiklos Szeredi return -EACCES; 26522590e41SMiklos Szeredi } 26622590e41SMiklos Szeredi } else { 267e6305c43SAl Viro retval = generic_permission(inode, mask, NULL); 26822590e41SMiklos Szeredi } 2691da177e4SLinus Torvalds if (retval) 2701da177e4SLinus Torvalds return retval; 2711da177e4SLinus Torvalds 27208ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 27308ce5f16SSerge E. Hallyn if (retval) 27408ce5f16SSerge E. Hallyn return retval; 27508ce5f16SSerge E. Hallyn 276e6305c43SAl Viro return security_inode_permission(inode, 277b77b0646SAl Viro mask & (MAY_READ|MAY_WRITE|MAY_EXEC)); 2781da177e4SLinus Torvalds } 2791da177e4SLinus Torvalds 280e4543eddSChristoph Hellwig /** 281e4543eddSChristoph Hellwig * vfs_permission - check for access rights to a given path 282e4543eddSChristoph Hellwig * @nd: lookup result that describes the path 283e4543eddSChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 284e4543eddSChristoph Hellwig * 285e4543eddSChristoph Hellwig * Used to check for read/write/execute permissions on a path. 286e4543eddSChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 287e4543eddSChristoph Hellwig * for filesystem access without changing the "normal" uids which 288e4543eddSChristoph Hellwig * are used for other things. 289e4543eddSChristoph Hellwig */ 290e4543eddSChristoph Hellwig int vfs_permission(struct nameidata *nd, int mask) 291e4543eddSChristoph Hellwig { 292f419a2e3SAl Viro return inode_permission(nd->path.dentry->d_inode, mask); 293e4543eddSChristoph Hellwig } 294e4543eddSChristoph Hellwig 2958c744fb8SChristoph Hellwig /** 2968c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2978c744fb8SChristoph Hellwig * @file: file to check access rights for 2988c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2998c744fb8SChristoph Hellwig * 3008c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3018c744fb8SChristoph Hellwig * file. 3028c744fb8SChristoph Hellwig * 3038c744fb8SChristoph Hellwig * Note: 3048c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 3058c744fb8SChristoph Hellwig * be done using vfs_permission(). 3068c744fb8SChristoph Hellwig */ 3078c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3088c744fb8SChristoph Hellwig { 309f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3108c744fb8SChristoph Hellwig } 3118c744fb8SChristoph Hellwig 3121da177e4SLinus Torvalds /* 3131da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3141da177e4SLinus Torvalds * put_write_access() releases this write permission. 3151da177e4SLinus Torvalds * This is used for regular files. 3161da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3171da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3181da177e4SLinus Torvalds * can have the following values: 3191da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3201da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3211da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3241da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3251da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3261da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3271da177e4SLinus Torvalds * the inode->i_lock spinlock. 3281da177e4SLinus Torvalds */ 3291da177e4SLinus Torvalds 3301da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3311da177e4SLinus Torvalds { 3321da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3331da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3341da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3351da177e4SLinus Torvalds return -ETXTBSY; 3361da177e4SLinus Torvalds } 3371da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3381da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds return 0; 3411da177e4SLinus Torvalds } 3421da177e4SLinus Torvalds 3431da177e4SLinus Torvalds int deny_write_access(struct file * file) 3441da177e4SLinus Torvalds { 3450f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3461da177e4SLinus Torvalds 3471da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3481da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3491da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3501da177e4SLinus Torvalds return -ETXTBSY; 3511da177e4SLinus Torvalds } 3521da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3531da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3541da177e4SLinus Torvalds 3551da177e4SLinus Torvalds return 0; 3561da177e4SLinus Torvalds } 3571da177e4SLinus Torvalds 3581d957f9bSJan Blunck /** 3595dd784d0SJan Blunck * path_get - get a reference to a path 3605dd784d0SJan Blunck * @path: path to get the reference to 3615dd784d0SJan Blunck * 3625dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3635dd784d0SJan Blunck */ 3645dd784d0SJan Blunck void path_get(struct path *path) 3655dd784d0SJan Blunck { 3665dd784d0SJan Blunck mntget(path->mnt); 3675dd784d0SJan Blunck dget(path->dentry); 3685dd784d0SJan Blunck } 3695dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3705dd784d0SJan Blunck 3715dd784d0SJan Blunck /** 3721d957f9bSJan Blunck * path_put - put a reference to a path 3731d957f9bSJan Blunck * @path: path to put the reference to 3741d957f9bSJan Blunck * 3751d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3761d957f9bSJan Blunck */ 3771d957f9bSJan Blunck void path_put(struct path *path) 3781da177e4SLinus Torvalds { 3791d957f9bSJan Blunck dput(path->dentry); 3801d957f9bSJan Blunck mntput(path->mnt); 3811da177e4SLinus Torvalds } 3821d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3831da177e4SLinus Torvalds 384834f2a4aSTrond Myklebust /** 385834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 386834f2a4aSTrond Myklebust * @nd: pointer to nameidata 387834f2a4aSTrond Myklebust */ 388834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 389834f2a4aSTrond Myklebust { 3900f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 391834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 392834f2a4aSTrond Myklebust else 393834f2a4aSTrond Myklebust fput(nd->intent.open.file); 394834f2a4aSTrond Myklebust } 395834f2a4aSTrond Myklebust 396bcdc5e01SIan Kent static inline struct dentry * 397bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 398bcdc5e01SIan Kent { 399bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 400bcdc5e01SIan Kent if (unlikely(status <= 0)) { 401bcdc5e01SIan Kent /* 402bcdc5e01SIan Kent * The dentry failed validation. 403bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 404bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 405bcdc5e01SIan Kent * to return a fail status. 406bcdc5e01SIan Kent */ 407bcdc5e01SIan Kent if (!status) { 408bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 409bcdc5e01SIan Kent dput(dentry); 410bcdc5e01SIan Kent dentry = NULL; 411bcdc5e01SIan Kent } 412bcdc5e01SIan Kent } else { 413bcdc5e01SIan Kent dput(dentry); 414bcdc5e01SIan Kent dentry = ERR_PTR(status); 415bcdc5e01SIan Kent } 416bcdc5e01SIan Kent } 417bcdc5e01SIan Kent return dentry; 418bcdc5e01SIan Kent } 419bcdc5e01SIan Kent 4201da177e4SLinus Torvalds /* 4211da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4221da177e4SLinus Torvalds * SMP-safe 4231da177e4SLinus Torvalds */ 4241da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4251da177e4SLinus Torvalds { 4261da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4271da177e4SLinus Torvalds 4281da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4291da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4301da177e4SLinus Torvalds */ 4311da177e4SLinus Torvalds if (!dentry) 4321da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4331da177e4SLinus Torvalds 434bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 435bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 436bcdc5e01SIan Kent 4371da177e4SLinus Torvalds return dentry; 4381da177e4SLinus Torvalds } 4391da177e4SLinus Torvalds 4401da177e4SLinus Torvalds /* 4411da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4421da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4431da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4441da177e4SLinus Torvalds * MAY_EXEC permission. 4451da177e4SLinus Torvalds * 4461da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4471da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4481da177e4SLinus Torvalds * complete permission check. 4491da177e4SLinus Torvalds */ 450672b16b2SAl Viro static int exec_permission_lite(struct inode *inode) 4511da177e4SLinus Torvalds { 4521da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4531da177e4SLinus Torvalds 4541da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4551da177e4SLinus Torvalds return -EAGAIN; 4561da177e4SLinus Torvalds 4571da177e4SLinus Torvalds if (current->fsuid == inode->i_uid) 4581da177e4SLinus Torvalds mode >>= 6; 4591da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4601da177e4SLinus Torvalds mode >>= 3; 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds if (mode & MAY_EXEC) 4631da177e4SLinus Torvalds goto ok; 4641da177e4SLinus Torvalds 4651da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4661da177e4SLinus Torvalds goto ok; 4671da177e4SLinus Torvalds 4681da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4691da177e4SLinus Torvalds goto ok; 4701da177e4SLinus Torvalds 4711da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4721da177e4SLinus Torvalds goto ok; 4731da177e4SLinus Torvalds 4741da177e4SLinus Torvalds return -EACCES; 4751da177e4SLinus Torvalds ok: 476b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4771da177e4SLinus Torvalds } 4781da177e4SLinus Torvalds 4791da177e4SLinus Torvalds /* 4801da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4811da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4821da177e4SLinus Torvalds * 4831da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4841da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4851da177e4SLinus Torvalds * SMP-safe 4861da177e4SLinus Torvalds */ 4871da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4881da177e4SLinus Torvalds { 4891da177e4SLinus Torvalds struct dentry * result; 4901da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4911da177e4SLinus Torvalds 4921b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 4931da177e4SLinus Torvalds /* 4941da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 4951da177e4SLinus Torvalds * while we waited for the directory semaphore.. 4961da177e4SLinus Torvalds * 4971da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 4981da177e4SLinus Torvalds * avoid unnecessary cache lookups. 4991da177e4SLinus Torvalds * 5001da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 5011da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 5021da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 5031da177e4SLinus Torvalds * fast walk). 5041da177e4SLinus Torvalds * 5051da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 5061da177e4SLinus Torvalds */ 5071da177e4SLinus Torvalds result = d_lookup(parent, name); 5081da177e4SLinus Torvalds if (!result) { 509d70b67c8SMiklos Szeredi struct dentry *dentry; 510d70b67c8SMiklos Szeredi 511d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 512d70b67c8SMiklos Szeredi result = ERR_PTR(-ENOENT); 513d70b67c8SMiklos Szeredi if (IS_DEADDIR(dir)) 514d70b67c8SMiklos Szeredi goto out_unlock; 515d70b67c8SMiklos Szeredi 516d70b67c8SMiklos Szeredi dentry = d_alloc(parent, name); 5171da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5181da177e4SLinus Torvalds if (dentry) { 5191da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5201da177e4SLinus Torvalds if (result) 5211da177e4SLinus Torvalds dput(dentry); 5221da177e4SLinus Torvalds else 5231da177e4SLinus Torvalds result = dentry; 5241da177e4SLinus Torvalds } 525d70b67c8SMiklos Szeredi out_unlock: 5261b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5271da177e4SLinus Torvalds return result; 5281da177e4SLinus Torvalds } 5291da177e4SLinus Torvalds 5301da177e4SLinus Torvalds /* 5311da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5321da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5331da177e4SLinus Torvalds */ 5341b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5351da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 536bcdc5e01SIan Kent result = do_revalidate(result, nd); 537bcdc5e01SIan Kent if (!result) 5381da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5391da177e4SLinus Torvalds } 5401da177e4SLinus Torvalds return result; 5411da177e4SLinus Torvalds } 5421da177e4SLinus Torvalds 5431da177e4SLinus Torvalds /* SMP-safe */ 5447f2da1e7SAl Viro static __always_inline void 5451da177e4SLinus Torvalds walk_init_root(const char *name, struct nameidata *nd) 5461da177e4SLinus Torvalds { 547e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 548e518ddb7SAndreas Mohr 549e518ddb7SAndreas Mohr read_lock(&fs->lock); 5506ac08c39SJan Blunck nd->path = fs->root; 5516ac08c39SJan Blunck path_get(&fs->root); 552e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5531da177e4SLinus Torvalds } 5541da177e4SLinus Torvalds 555a02f76c3SAl Viro /* 556a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 557a02f76c3SAl Viro * file system returns an ESTALE. 558a02f76c3SAl Viro * 559a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 560a02f76c3SAl Viro * instead of relying on the dcache. 561a02f76c3SAl Viro */ 562a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 563a02f76c3SAl Viro { 564a02f76c3SAl Viro struct path save = nd->path; 565a02f76c3SAl Viro int result; 566a02f76c3SAl Viro 567a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 568c8e7f449SJan Blunck path_get(&save); 569a02f76c3SAl Viro 570a02f76c3SAl Viro result = __link_path_walk(name, nd); 571a02f76c3SAl Viro if (result == -ESTALE) { 572a02f76c3SAl Viro /* nd->path had been dropped */ 573a02f76c3SAl Viro nd->path = save; 574c8e7f449SJan Blunck path_get(&nd->path); 575a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 576a02f76c3SAl Viro result = __link_path_walk(name, nd); 577a02f76c3SAl Viro } 578a02f76c3SAl Viro 579a02f76c3SAl Viro path_put(&save); 580a02f76c3SAl Viro 581a02f76c3SAl Viro return result; 582a02f76c3SAl Viro } 583a02f76c3SAl Viro 584f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5851da177e4SLinus Torvalds { 5861da177e4SLinus Torvalds int res = 0; 5871da177e4SLinus Torvalds char *name; 5881da177e4SLinus Torvalds if (IS_ERR(link)) 5891da177e4SLinus Torvalds goto fail; 5901da177e4SLinus Torvalds 5911da177e4SLinus Torvalds if (*link == '/') { 5921d957f9bSJan Blunck path_put(&nd->path); 5937f2da1e7SAl Viro walk_init_root(link, nd); 5941da177e4SLinus Torvalds } 5951da177e4SLinus Torvalds res = link_path_walk(link, nd); 5961da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5971da177e4SLinus Torvalds return res; 5981da177e4SLinus Torvalds /* 5991da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 6001da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 6011da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 6021da177e4SLinus Torvalds */ 6031da177e4SLinus Torvalds name = __getname(); 6041da177e4SLinus Torvalds if (unlikely(!name)) { 6051d957f9bSJan Blunck path_put(&nd->path); 6061da177e4SLinus Torvalds return -ENOMEM; 6071da177e4SLinus Torvalds } 6081da177e4SLinus Torvalds strcpy(name, nd->last.name); 6091da177e4SLinus Torvalds nd->last.name = name; 6101da177e4SLinus Torvalds return 0; 6111da177e4SLinus Torvalds fail: 6121d957f9bSJan Blunck path_put(&nd->path); 6131da177e4SLinus Torvalds return PTR_ERR(link); 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 6161d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 617051d3812SIan Kent { 618051d3812SIan Kent dput(path->dentry); 6194ac91378SJan Blunck if (path->mnt != nd->path.mnt) 620051d3812SIan Kent mntput(path->mnt); 621051d3812SIan Kent } 622051d3812SIan Kent 623051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 624051d3812SIan Kent { 6254ac91378SJan Blunck dput(nd->path.dentry); 6264ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6274ac91378SJan Blunck mntput(nd->path.mnt); 6284ac91378SJan Blunck nd->path.mnt = path->mnt; 6294ac91378SJan Blunck nd->path.dentry = path->dentry; 630051d3812SIan Kent } 631051d3812SIan Kent 632f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6331da177e4SLinus Torvalds { 6341da177e4SLinus Torvalds int error; 635cc314eefSLinus Torvalds void *cookie; 636cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6371da177e4SLinus Torvalds 638d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6391da177e4SLinus Torvalds nd_set_link(nd, NULL); 640cd4e91d3SAl Viro 6414ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 642051d3812SIan Kent path_to_nameidata(path, nd); 643051d3812SIan Kent dget(dentry); 644051d3812SIan Kent } 645cd4e91d3SAl Viro mntget(path->mnt); 646cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 647cc314eefSLinus Torvalds error = PTR_ERR(cookie); 648cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6491da177e4SLinus Torvalds char *s = nd_get_link(nd); 650cc314eefSLinus Torvalds error = 0; 6511da177e4SLinus Torvalds if (s) 6521da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6531da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 654cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6551da177e4SLinus Torvalds } 65609da5916SJan Blunck path_put(path); 6571da177e4SLinus Torvalds 6581da177e4SLinus Torvalds return error; 6591da177e4SLinus Torvalds } 6601da177e4SLinus Torvalds 6611da177e4SLinus Torvalds /* 6621da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6631da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6641da177e4SLinus Torvalds * 6651da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6661da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6671da177e4SLinus Torvalds */ 66890ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6691da177e4SLinus Torvalds { 6701da177e4SLinus Torvalds int err = -ELOOP; 6711da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6721da177e4SLinus Torvalds goto loop; 6731da177e4SLinus Torvalds if (current->total_link_count >= 40) 6741da177e4SLinus Torvalds goto loop; 6751da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6761da177e4SLinus Torvalds cond_resched(); 67790ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6781da177e4SLinus Torvalds if (err) 6791da177e4SLinus Torvalds goto loop; 6801da177e4SLinus Torvalds current->link_count++; 6811da177e4SLinus Torvalds current->total_link_count++; 6821da177e4SLinus Torvalds nd->depth++; 683cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6841da177e4SLinus Torvalds current->link_count--; 6851da177e4SLinus Torvalds nd->depth--; 6861da177e4SLinus Torvalds return err; 6871da177e4SLinus Torvalds loop: 6881d957f9bSJan Blunck path_put_conditional(path, nd); 6891d957f9bSJan Blunck path_put(&nd->path); 6901da177e4SLinus Torvalds return err; 6911da177e4SLinus Torvalds } 6921da177e4SLinus Torvalds 6931da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 6941da177e4SLinus Torvalds { 6951da177e4SLinus Torvalds struct vfsmount *parent; 6961da177e4SLinus Torvalds struct dentry *mountpoint; 6971da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6981da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 6991da177e4SLinus Torvalds if (parent == *mnt) { 7001da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7011da177e4SLinus Torvalds return 0; 7021da177e4SLinus Torvalds } 7031da177e4SLinus Torvalds mntget(parent); 7041da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 7051da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7061da177e4SLinus Torvalds dput(*dentry); 7071da177e4SLinus Torvalds *dentry = mountpoint; 7081da177e4SLinus Torvalds mntput(*mnt); 7091da177e4SLinus Torvalds *mnt = parent; 7101da177e4SLinus Torvalds return 1; 7111da177e4SLinus Torvalds } 7121da177e4SLinus Torvalds 7131da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7141da177e4SLinus Torvalds * namespace.c 7151da177e4SLinus Torvalds */ 716463ffb2eSAl Viro static int __follow_mount(struct path *path) 717463ffb2eSAl Viro { 718463ffb2eSAl Viro int res = 0; 719463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 720463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 721463ffb2eSAl Viro if (!mounted) 722463ffb2eSAl Viro break; 723463ffb2eSAl Viro dput(path->dentry); 724463ffb2eSAl Viro if (res) 725463ffb2eSAl Viro mntput(path->mnt); 726463ffb2eSAl Viro path->mnt = mounted; 727463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 728463ffb2eSAl Viro res = 1; 729463ffb2eSAl Viro } 730463ffb2eSAl Viro return res; 731463ffb2eSAl Viro } 732463ffb2eSAl Viro 73358c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7341da177e4SLinus Torvalds { 7351da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7361da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7371da177e4SLinus Torvalds if (!mounted) 7381da177e4SLinus Torvalds break; 73958c465ebSAl Viro dput(*dentry); 7401da177e4SLinus Torvalds mntput(*mnt); 7411da177e4SLinus Torvalds *mnt = mounted; 7421da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds } 7451da177e4SLinus Torvalds 7461da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7471da177e4SLinus Torvalds * namespace.c 7481da177e4SLinus Torvalds */ 749e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7501da177e4SLinus Torvalds { 7511da177e4SLinus Torvalds struct vfsmount *mounted; 7521da177e4SLinus Torvalds 7531da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7541da177e4SLinus Torvalds if (mounted) { 755e13b210fSAl Viro dput(*dentry); 7561da177e4SLinus Torvalds mntput(*mnt); 7571da177e4SLinus Torvalds *mnt = mounted; 7581da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7591da177e4SLinus Torvalds return 1; 7601da177e4SLinus Torvalds } 7611da177e4SLinus Torvalds return 0; 7621da177e4SLinus Torvalds } 7631da177e4SLinus Torvalds 764f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7651da177e4SLinus Torvalds { 766e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 767e518ddb7SAndreas Mohr 7681da177e4SLinus Torvalds while(1) { 7691da177e4SLinus Torvalds struct vfsmount *parent; 7704ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7711da177e4SLinus Torvalds 772e518ddb7SAndreas Mohr read_lock(&fs->lock); 7736ac08c39SJan Blunck if (nd->path.dentry == fs->root.dentry && 7746ac08c39SJan Blunck nd->path.mnt == fs->root.mnt) { 775e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7761da177e4SLinus Torvalds break; 7771da177e4SLinus Torvalds } 778e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7791da177e4SLinus Torvalds spin_lock(&dcache_lock); 7804ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7814ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7821da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7831da177e4SLinus Torvalds dput(old); 7841da177e4SLinus Torvalds break; 7851da177e4SLinus Torvalds } 7861da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7871da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7884ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7894ac91378SJan Blunck if (parent == nd->path.mnt) { 7901da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7911da177e4SLinus Torvalds break; 7921da177e4SLinus Torvalds } 7931da177e4SLinus Torvalds mntget(parent); 7944ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7951da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7961da177e4SLinus Torvalds dput(old); 7974ac91378SJan Blunck mntput(nd->path.mnt); 7984ac91378SJan Blunck nd->path.mnt = parent; 7991da177e4SLinus Torvalds } 8004ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 8011da177e4SLinus Torvalds } 8021da177e4SLinus Torvalds 8031da177e4SLinus Torvalds /* 8041da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 8051da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 8061da177e4SLinus Torvalds * It _is_ time-critical. 8071da177e4SLinus Torvalds */ 8081da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 8091da177e4SLinus Torvalds struct path *path) 8101da177e4SLinus Torvalds { 8114ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 8124ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 8131da177e4SLinus Torvalds 8141da177e4SLinus Torvalds if (!dentry) 8151da177e4SLinus Torvalds goto need_lookup; 8161da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 8171da177e4SLinus Torvalds goto need_revalidate; 8181da177e4SLinus Torvalds done: 8191da177e4SLinus Torvalds path->mnt = mnt; 8201da177e4SLinus Torvalds path->dentry = dentry; 821634ee701SAl Viro __follow_mount(path); 8221da177e4SLinus Torvalds return 0; 8231da177e4SLinus Torvalds 8241da177e4SLinus Torvalds need_lookup: 8254ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8261da177e4SLinus Torvalds if (IS_ERR(dentry)) 8271da177e4SLinus Torvalds goto fail; 8281da177e4SLinus Torvalds goto done; 8291da177e4SLinus Torvalds 8301da177e4SLinus Torvalds need_revalidate: 831bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 832bcdc5e01SIan Kent if (!dentry) 8331da177e4SLinus Torvalds goto need_lookup; 834bcdc5e01SIan Kent if (IS_ERR(dentry)) 835bcdc5e01SIan Kent goto fail; 836bcdc5e01SIan Kent goto done; 8371da177e4SLinus Torvalds 8381da177e4SLinus Torvalds fail: 8391da177e4SLinus Torvalds return PTR_ERR(dentry); 8401da177e4SLinus Torvalds } 8411da177e4SLinus Torvalds 8421da177e4SLinus Torvalds /* 8431da177e4SLinus Torvalds * Name resolution. 844ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 845ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8461da177e4SLinus Torvalds * 847ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 848ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8491da177e4SLinus Torvalds */ 850fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8511da177e4SLinus Torvalds { 8521da177e4SLinus Torvalds struct path next; 8531da177e4SLinus Torvalds struct inode *inode; 8541da177e4SLinus Torvalds int err; 8551da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8561da177e4SLinus Torvalds 8571da177e4SLinus Torvalds while (*name=='/') 8581da177e4SLinus Torvalds name++; 8591da177e4SLinus Torvalds if (!*name) 8601da177e4SLinus Torvalds goto return_reval; 8611da177e4SLinus Torvalds 8624ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8631da177e4SLinus Torvalds if (nd->depth) 864f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8651da177e4SLinus Torvalds 8661da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8671da177e4SLinus Torvalds for(;;) { 8681da177e4SLinus Torvalds unsigned long hash; 8691da177e4SLinus Torvalds struct qstr this; 8701da177e4SLinus Torvalds unsigned int c; 8711da177e4SLinus Torvalds 872cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 873672b16b2SAl Viro err = exec_permission_lite(inode); 874e4543eddSChristoph Hellwig if (err == -EAGAIN) 875e4543eddSChristoph Hellwig err = vfs_permission(nd, MAY_EXEC); 8761da177e4SLinus Torvalds if (err) 8771da177e4SLinus Torvalds break; 8781da177e4SLinus Torvalds 8791da177e4SLinus Torvalds this.name = name; 8801da177e4SLinus Torvalds c = *(const unsigned char *)name; 8811da177e4SLinus Torvalds 8821da177e4SLinus Torvalds hash = init_name_hash(); 8831da177e4SLinus Torvalds do { 8841da177e4SLinus Torvalds name++; 8851da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8861da177e4SLinus Torvalds c = *(const unsigned char *)name; 8871da177e4SLinus Torvalds } while (c && (c != '/')); 8881da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8891da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8901da177e4SLinus Torvalds 8911da177e4SLinus Torvalds /* remove trailing slashes? */ 8921da177e4SLinus Torvalds if (!c) 8931da177e4SLinus Torvalds goto last_component; 8941da177e4SLinus Torvalds while (*++name == '/'); 8951da177e4SLinus Torvalds if (!*name) 8961da177e4SLinus Torvalds goto last_with_slashes; 8971da177e4SLinus Torvalds 8981da177e4SLinus Torvalds /* 8991da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 9001da177e4SLinus Torvalds * to be able to know about the current root directory and 9011da177e4SLinus Torvalds * parent relationships. 9021da177e4SLinus Torvalds */ 9031da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9041da177e4SLinus Torvalds default: 9051da177e4SLinus Torvalds break; 9061da177e4SLinus Torvalds case 2: 9071da177e4SLinus Torvalds if (this.name[1] != '.') 9081da177e4SLinus Torvalds break; 90958c465ebSAl Viro follow_dotdot(nd); 9104ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9111da177e4SLinus Torvalds /* fallthrough */ 9121da177e4SLinus Torvalds case 1: 9131da177e4SLinus Torvalds continue; 9141da177e4SLinus Torvalds } 9151da177e4SLinus Torvalds /* 9161da177e4SLinus Torvalds * See if the low-level filesystem might want 9171da177e4SLinus Torvalds * to use its own hash.. 9181da177e4SLinus Torvalds */ 9194ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9204ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9214ac91378SJan Blunck &this); 9221da177e4SLinus Torvalds if (err < 0) 9231da177e4SLinus Torvalds break; 9241da177e4SLinus Torvalds } 9251da177e4SLinus Torvalds /* This does the actual lookups.. */ 9261da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9271da177e4SLinus Torvalds if (err) 9281da177e4SLinus Torvalds break; 9291da177e4SLinus Torvalds 9301da177e4SLinus Torvalds err = -ENOENT; 9311da177e4SLinus Torvalds inode = next.dentry->d_inode; 9321da177e4SLinus Torvalds if (!inode) 9331da177e4SLinus Torvalds goto out_dput; 9341da177e4SLinus Torvalds err = -ENOTDIR; 9351da177e4SLinus Torvalds if (!inode->i_op) 9361da177e4SLinus Torvalds goto out_dput; 9371da177e4SLinus Torvalds 9381da177e4SLinus Torvalds if (inode->i_op->follow_link) { 93990ebe565SAl Viro err = do_follow_link(&next, nd); 9401da177e4SLinus Torvalds if (err) 9411da177e4SLinus Torvalds goto return_err; 9421da177e4SLinus Torvalds err = -ENOENT; 9434ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9441da177e4SLinus Torvalds if (!inode) 9451da177e4SLinus Torvalds break; 9461da177e4SLinus Torvalds err = -ENOTDIR; 9471da177e4SLinus Torvalds if (!inode->i_op) 9481da177e4SLinus Torvalds break; 94909dd17d3SMiklos Szeredi } else 95009dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9511da177e4SLinus Torvalds err = -ENOTDIR; 9521da177e4SLinus Torvalds if (!inode->i_op->lookup) 9531da177e4SLinus Torvalds break; 9541da177e4SLinus Torvalds continue; 9551da177e4SLinus Torvalds /* here ends the main loop */ 9561da177e4SLinus Torvalds 9571da177e4SLinus Torvalds last_with_slashes: 9581da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9591da177e4SLinus Torvalds last_component: 960f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 961f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9621da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9631da177e4SLinus Torvalds goto lookup_parent; 9641da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9651da177e4SLinus Torvalds default: 9661da177e4SLinus Torvalds break; 9671da177e4SLinus Torvalds case 2: 9681da177e4SLinus Torvalds if (this.name[1] != '.') 9691da177e4SLinus Torvalds break; 97058c465ebSAl Viro follow_dotdot(nd); 9714ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9721da177e4SLinus Torvalds /* fallthrough */ 9731da177e4SLinus Torvalds case 1: 9741da177e4SLinus Torvalds goto return_reval; 9751da177e4SLinus Torvalds } 9764ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9774ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9784ac91378SJan Blunck &this); 9791da177e4SLinus Torvalds if (err < 0) 9801da177e4SLinus Torvalds break; 9811da177e4SLinus Torvalds } 9821da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9831da177e4SLinus Torvalds if (err) 9841da177e4SLinus Torvalds break; 9851da177e4SLinus Torvalds inode = next.dentry->d_inode; 9861da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 9871da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 98890ebe565SAl Viro err = do_follow_link(&next, nd); 9891da177e4SLinus Torvalds if (err) 9901da177e4SLinus Torvalds goto return_err; 9914ac91378SJan Blunck inode = nd->path.dentry->d_inode; 99209dd17d3SMiklos Szeredi } else 99309dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9941da177e4SLinus Torvalds err = -ENOENT; 9951da177e4SLinus Torvalds if (!inode) 9961da177e4SLinus Torvalds break; 9971da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9981da177e4SLinus Torvalds err = -ENOTDIR; 9991da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 10001da177e4SLinus Torvalds break; 10011da177e4SLinus Torvalds } 10021da177e4SLinus Torvalds goto return_base; 10031da177e4SLinus Torvalds lookup_parent: 10041da177e4SLinus Torvalds nd->last = this; 10051da177e4SLinus Torvalds nd->last_type = LAST_NORM; 10061da177e4SLinus Torvalds if (this.name[0] != '.') 10071da177e4SLinus Torvalds goto return_base; 10081da177e4SLinus Torvalds if (this.len == 1) 10091da177e4SLinus Torvalds nd->last_type = LAST_DOT; 10101da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 10111da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 10121da177e4SLinus Torvalds else 10131da177e4SLinus Torvalds goto return_base; 10141da177e4SLinus Torvalds return_reval: 10151da177e4SLinus Torvalds /* 10161da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 10171da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 10181da177e4SLinus Torvalds */ 10194ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 10204ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 10211da177e4SLinus Torvalds err = -ESTALE; 10221da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10234ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10244ac91378SJan Blunck nd->path.dentry, nd)) 10251da177e4SLinus Torvalds break; 10261da177e4SLinus Torvalds } 10271da177e4SLinus Torvalds return_base: 10281da177e4SLinus Torvalds return 0; 10291da177e4SLinus Torvalds out_dput: 10301d957f9bSJan Blunck path_put_conditional(&next, nd); 10311da177e4SLinus Torvalds break; 10321da177e4SLinus Torvalds } 10331d957f9bSJan Blunck path_put(&nd->path); 10341da177e4SLinus Torvalds return_err: 10351da177e4SLinus Torvalds return err; 10361da177e4SLinus Torvalds } 10371da177e4SLinus Torvalds 1038fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10391da177e4SLinus Torvalds { 10401da177e4SLinus Torvalds current->total_link_count = 0; 10411da177e4SLinus Torvalds return link_path_walk(name, nd); 10421da177e4SLinus Torvalds } 10431da177e4SLinus Torvalds 1044ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1045fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 10465590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 10471da177e4SLinus Torvalds { 1048ea3834d9SPrasanna Meda int retval = 0; 1049170aa3d0SUlrich Drepper int fput_needed; 1050170aa3d0SUlrich Drepper struct file *file; 1051e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 10521da177e4SLinus Torvalds 10531da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10541da177e4SLinus Torvalds nd->flags = flags; 10551da177e4SLinus Torvalds nd->depth = 0; 10561da177e4SLinus Torvalds 10571da177e4SLinus Torvalds if (*name=='/') { 1058e518ddb7SAndreas Mohr read_lock(&fs->lock); 10596ac08c39SJan Blunck nd->path = fs->root; 10606ac08c39SJan Blunck path_get(&fs->root); 1061e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10625590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1063e518ddb7SAndreas Mohr read_lock(&fs->lock); 10646ac08c39SJan Blunck nd->path = fs->pwd; 10656ac08c39SJan Blunck path_get(&fs->pwd); 1066e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10675590ff0dSUlrich Drepper } else { 10685590ff0dSUlrich Drepper struct dentry *dentry; 10695590ff0dSUlrich Drepper 10705590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10715590ff0dSUlrich Drepper retval = -EBADF; 1072170aa3d0SUlrich Drepper if (!file) 10736d09bb62STrond Myklebust goto out_fail; 10745590ff0dSUlrich Drepper 10750f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10765590ff0dSUlrich Drepper 10775590ff0dSUlrich Drepper retval = -ENOTDIR; 1078170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10796d09bb62STrond Myklebust goto fput_fail; 10805590ff0dSUlrich Drepper 10815590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1082170aa3d0SUlrich Drepper if (retval) 10836d09bb62STrond Myklebust goto fput_fail; 10845590ff0dSUlrich Drepper 10855dd784d0SJan Blunck nd->path = file->f_path; 10865dd784d0SJan Blunck path_get(&file->f_path); 10875590ff0dSUlrich Drepper 10885590ff0dSUlrich Drepper fput_light(file, fput_needed); 10891da177e4SLinus Torvalds } 10902dfdd266SJosef 'Jeff' Sipek 10912dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10924ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10934ac91378SJan Blunck nd->path.dentry->d_inode)) 10944ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10956d09bb62STrond Myklebust out_fail: 1096170aa3d0SUlrich Drepper return retval; 1097170aa3d0SUlrich Drepper 10986d09bb62STrond Myklebust fput_fail: 1099170aa3d0SUlrich Drepper fput_light(file, fput_needed); 11006d09bb62STrond Myklebust goto out_fail; 11011da177e4SLinus Torvalds } 11021da177e4SLinus Torvalds 1103fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 11045590ff0dSUlrich Drepper struct nameidata *nd) 11055590ff0dSUlrich Drepper { 11065590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 11075590ff0dSUlrich Drepper } 11085590ff0dSUlrich Drepper 110916f18200SJosef 'Jeff' Sipek /** 111016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 111116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 111216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 111316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 111416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 111516f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 111616f18200SJosef 'Jeff' Sipek */ 111716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 111816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 111916f18200SJosef 'Jeff' Sipek struct nameidata *nd) 112016f18200SJosef 'Jeff' Sipek { 112116f18200SJosef 'Jeff' Sipek int retval; 112216f18200SJosef 'Jeff' Sipek 112316f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 112416f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 112516f18200SJosef 'Jeff' Sipek nd->flags = flags; 112616f18200SJosef 'Jeff' Sipek nd->depth = 0; 112716f18200SJosef 'Jeff' Sipek 1128c8e7f449SJan Blunck nd->path.dentry = dentry; 1129c8e7f449SJan Blunck nd->path.mnt = mnt; 1130c8e7f449SJan Blunck path_get(&nd->path); 113116f18200SJosef 'Jeff' Sipek 113216f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11334ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11344ac91378SJan Blunck nd->path.dentry->d_inode)) 11354ac91378SJan Blunck audit_inode(name, nd->path.dentry); 113616f18200SJosef 'Jeff' Sipek 113716f18200SJosef 'Jeff' Sipek return retval; 113816f18200SJosef 'Jeff' Sipek 113916f18200SJosef 'Jeff' Sipek } 114016f18200SJosef 'Jeff' Sipek 11415590ff0dSUlrich Drepper static int __path_lookup_intent_open(int dfd, const char *name, 11425590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 11435590ff0dSUlrich Drepper int open_flags, int create_mode) 1144834f2a4aSTrond Myklebust { 1145834f2a4aSTrond Myklebust struct file *filp = get_empty_filp(); 1146834f2a4aSTrond Myklebust int err; 1147834f2a4aSTrond Myklebust 1148834f2a4aSTrond Myklebust if (filp == NULL) 1149834f2a4aSTrond Myklebust return -ENFILE; 1150834f2a4aSTrond Myklebust nd->intent.open.file = filp; 1151834f2a4aSTrond Myklebust nd->intent.open.flags = open_flags; 1152834f2a4aSTrond Myklebust nd->intent.open.create_mode = create_mode; 11535590ff0dSUlrich Drepper err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 1154834f2a4aSTrond Myklebust if (IS_ERR(nd->intent.open.file)) { 1155834f2a4aSTrond Myklebust if (err == 0) { 1156834f2a4aSTrond Myklebust err = PTR_ERR(nd->intent.open.file); 11571d957f9bSJan Blunck path_put(&nd->path); 1158834f2a4aSTrond Myklebust } 1159834f2a4aSTrond Myklebust } else if (err != 0) 1160834f2a4aSTrond Myklebust release_open_intent(nd); 1161834f2a4aSTrond Myklebust return err; 1162834f2a4aSTrond Myklebust } 1163834f2a4aSTrond Myklebust 1164834f2a4aSTrond Myklebust /** 1165834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 11667045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1167834f2a4aSTrond Myklebust * @name: pointer to file name 1168834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1169834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1170834f2a4aSTrond Myklebust * @open_flags: open intent flags 1171834f2a4aSTrond Myklebust */ 11725590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1173834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1174834f2a4aSTrond Myklebust { 11755590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags, nd, 1176834f2a4aSTrond Myklebust open_flags, 0); 1177834f2a4aSTrond Myklebust } 1178834f2a4aSTrond Myklebust 1179834f2a4aSTrond Myklebust /** 1180834f2a4aSTrond Myklebust * path_lookup_create - lookup a file path with open + create intent 11817045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1182834f2a4aSTrond Myklebust * @name: pointer to file name 1183834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1184834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1185834f2a4aSTrond Myklebust * @open_flags: open intent flags 1186834f2a4aSTrond Myklebust * @create_mode: create intent flags 1187834f2a4aSTrond Myklebust */ 11885590ff0dSUlrich Drepper static int path_lookup_create(int dfd, const char *name, 11895590ff0dSUlrich Drepper unsigned int lookup_flags, struct nameidata *nd, 11905590ff0dSUlrich Drepper int open_flags, int create_mode) 1191834f2a4aSTrond Myklebust { 11925590ff0dSUlrich Drepper return __path_lookup_intent_open(dfd, name, lookup_flags|LOOKUP_CREATE, 11935590ff0dSUlrich Drepper nd, open_flags, create_mode); 1194834f2a4aSTrond Myklebust } 1195834f2a4aSTrond Myklebust 1196834f2a4aSTrond Myklebust int __user_path_lookup_open(const char __user *name, unsigned int lookup_flags, 1197834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1198834f2a4aSTrond Myklebust { 1199834f2a4aSTrond Myklebust char *tmp = getname(name); 1200834f2a4aSTrond Myklebust int err = PTR_ERR(tmp); 1201834f2a4aSTrond Myklebust 1202834f2a4aSTrond Myklebust if (!IS_ERR(tmp)) { 12035590ff0dSUlrich Drepper err = __path_lookup_intent_open(AT_FDCWD, tmp, lookup_flags, nd, open_flags, 0); 1204834f2a4aSTrond Myklebust putname(tmp); 1205834f2a4aSTrond Myklebust } 1206834f2a4aSTrond Myklebust return err; 1207834f2a4aSTrond Myklebust } 1208834f2a4aSTrond Myklebust 1209eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1210eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 12111da177e4SLinus Torvalds { 12121da177e4SLinus Torvalds struct dentry *dentry; 12131da177e4SLinus Torvalds struct inode *inode; 12141da177e4SLinus Torvalds int err; 12151da177e4SLinus Torvalds 12161da177e4SLinus Torvalds inode = base->d_inode; 12171da177e4SLinus Torvalds 12181da177e4SLinus Torvalds /* 12191da177e4SLinus Torvalds * See if the low-level filesystem might want 12201da177e4SLinus Torvalds * to use its own hash.. 12211da177e4SLinus Torvalds */ 12221da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 12231da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 12241da177e4SLinus Torvalds dentry = ERR_PTR(err); 12251da177e4SLinus Torvalds if (err < 0) 12261da177e4SLinus Torvalds goto out; 12271da177e4SLinus Torvalds } 12281da177e4SLinus Torvalds 12291da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 12301da177e4SLinus Torvalds if (!dentry) { 1231d70b67c8SMiklos Szeredi struct dentry *new; 1232d70b67c8SMiklos Szeredi 1233d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1234d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1235d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1236d70b67c8SMiklos Szeredi goto out; 1237d70b67c8SMiklos Szeredi 1238d70b67c8SMiklos Szeredi new = d_alloc(base, name); 12391da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 12401da177e4SLinus Torvalds if (!new) 12411da177e4SLinus Torvalds goto out; 12421da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 12431da177e4SLinus Torvalds if (!dentry) 12441da177e4SLinus Torvalds dentry = new; 12451da177e4SLinus Torvalds else 12461da177e4SLinus Torvalds dput(new); 12471da177e4SLinus Torvalds } 12481da177e4SLinus Torvalds out: 12491da177e4SLinus Torvalds return dentry; 12501da177e4SLinus Torvalds } 12511da177e4SLinus Torvalds 1252057f6c01SJames Morris /* 1253057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1254057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1255057f6c01SJames Morris * SMP-safe. 1256057f6c01SJames Morris */ 1257a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 12581da177e4SLinus Torvalds { 1259eead1911SChristoph Hellwig int err; 1260eead1911SChristoph Hellwig 1261f419a2e3SAl Viro err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC); 1262eead1911SChristoph Hellwig if (err) 1263eead1911SChristoph Hellwig return ERR_PTR(err); 12644ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 12651da177e4SLinus Torvalds } 12661da177e4SLinus Torvalds 1267eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1268eead1911SChristoph Hellwig struct dentry *base, int len) 12691da177e4SLinus Torvalds { 12701da177e4SLinus Torvalds unsigned long hash; 12711da177e4SLinus Torvalds unsigned int c; 12721da177e4SLinus Torvalds 1273057f6c01SJames Morris this->name = name; 1274057f6c01SJames Morris this->len = len; 12751da177e4SLinus Torvalds if (!len) 1276057f6c01SJames Morris return -EACCES; 12771da177e4SLinus Torvalds 12781da177e4SLinus Torvalds hash = init_name_hash(); 12791da177e4SLinus Torvalds while (len--) { 12801da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12811da177e4SLinus Torvalds if (c == '/' || c == '\0') 1282057f6c01SJames Morris return -EACCES; 12831da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12841da177e4SLinus Torvalds } 1285057f6c01SJames Morris this->hash = end_name_hash(hash); 1286057f6c01SJames Morris return 0; 1287057f6c01SJames Morris } 12881da177e4SLinus Torvalds 1289eead1911SChristoph Hellwig /** 1290a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1291eead1911SChristoph Hellwig * @name: pathname component to lookup 1292eead1911SChristoph Hellwig * @base: base directory to lookup from 1293eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1294eead1911SChristoph Hellwig * 1295a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1296a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1297eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1298eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1299eead1911SChristoph Hellwig */ 1300057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1301057f6c01SJames Morris { 1302057f6c01SJames Morris int err; 1303057f6c01SJames Morris struct qstr this; 1304057f6c01SJames Morris 1305057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1306057f6c01SJames Morris if (err) 1307057f6c01SJames Morris return ERR_PTR(err); 1308eead1911SChristoph Hellwig 1309f419a2e3SAl Viro err = inode_permission(base->d_inode, MAY_EXEC); 1310eead1911SChristoph Hellwig if (err) 1311eead1911SChristoph Hellwig return ERR_PTR(err); 131249705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1313057f6c01SJames Morris } 1314057f6c01SJames Morris 1315eead1911SChristoph Hellwig /** 1316eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1317eead1911SChristoph Hellwig * @name: pathname component to lookup 1318eead1911SChristoph Hellwig * @base: base directory to lookup from 1319eead1911SChristoph Hellwig * 1320eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1321eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1322eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1323eead1911SChristoph Hellwig * 1324eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1325eead1911SChristoph Hellwig */ 1326eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1327057f6c01SJames Morris { 1328057f6c01SJames Morris int err; 1329057f6c01SJames Morris struct qstr this; 1330057f6c01SJames Morris 1331eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1332057f6c01SJames Morris if (err) 1333057f6c01SJames Morris return ERR_PTR(err); 1334eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 13351da177e4SLinus Torvalds } 13361da177e4SLinus Torvalds 13372d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 13382d8f3038SAl Viro struct path *path) 13391da177e4SLinus Torvalds { 13402d8f3038SAl Viro struct nameidata nd; 13411da177e4SLinus Torvalds char *tmp = getname(name); 13421da177e4SLinus Torvalds int err = PTR_ERR(tmp); 13431da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 13442d8f3038SAl Viro 13452d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 13462d8f3038SAl Viro 13472d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 13481da177e4SLinus Torvalds putname(tmp); 13492d8f3038SAl Viro if (!err) 13502d8f3038SAl Viro *path = nd.path; 13511da177e4SLinus Torvalds } 13521da177e4SLinus Torvalds return err; 13531da177e4SLinus Torvalds } 13541da177e4SLinus Torvalds 13552ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 13562ad94ae6SAl Viro struct nameidata *nd, char **name) 13572ad94ae6SAl Viro { 13582ad94ae6SAl Viro char *s = getname(path); 13592ad94ae6SAl Viro int error; 13602ad94ae6SAl Viro 13612ad94ae6SAl Viro if (IS_ERR(s)) 13622ad94ae6SAl Viro return PTR_ERR(s); 13632ad94ae6SAl Viro 13642ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 13652ad94ae6SAl Viro if (error) 13662ad94ae6SAl Viro putname(s); 13672ad94ae6SAl Viro else 13682ad94ae6SAl Viro *name = s; 13692ad94ae6SAl Viro 13702ad94ae6SAl Viro return error; 13712ad94ae6SAl Viro } 13722ad94ae6SAl Viro 13731da177e4SLinus Torvalds /* 13741da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 13751da177e4SLinus Torvalds * minimal. 13761da177e4SLinus Torvalds */ 13771da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 13781da177e4SLinus Torvalds { 13791da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 13801da177e4SLinus Torvalds return 0; 13811da177e4SLinus Torvalds if (inode->i_uid == current->fsuid) 13821da177e4SLinus Torvalds return 0; 13831da177e4SLinus Torvalds if (dir->i_uid == current->fsuid) 13841da177e4SLinus Torvalds return 0; 13851da177e4SLinus Torvalds return !capable(CAP_FOWNER); 13861da177e4SLinus Torvalds } 13871da177e4SLinus Torvalds 13881da177e4SLinus Torvalds /* 13891da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 13901da177e4SLinus Torvalds * whether the type of victim is right. 13911da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 13921da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 13931da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 13941da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13951da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13961da177e4SLinus Torvalds * a. be owner of dir, or 13971da177e4SLinus Torvalds * b. be owner of victim, or 13981da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13991da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 14001da177e4SLinus Torvalds * links pointing to it. 14011da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 14021da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 14031da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 14041da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 14051da177e4SLinus Torvalds * nfs_async_unlink(). 14061da177e4SLinus Torvalds */ 1407858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 14081da177e4SLinus Torvalds { 14091da177e4SLinus Torvalds int error; 14101da177e4SLinus Torvalds 14111da177e4SLinus Torvalds if (!victim->d_inode) 14121da177e4SLinus Torvalds return -ENOENT; 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 14155a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 14161da177e4SLinus Torvalds 1417f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 14181da177e4SLinus Torvalds if (error) 14191da177e4SLinus Torvalds return error; 14201da177e4SLinus Torvalds if (IS_APPEND(dir)) 14211da177e4SLinus Torvalds return -EPERM; 14221da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 14231da177e4SLinus Torvalds IS_IMMUTABLE(victim->d_inode)) 14241da177e4SLinus Torvalds return -EPERM; 14251da177e4SLinus Torvalds if (isdir) { 14261da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 14271da177e4SLinus Torvalds return -ENOTDIR; 14281da177e4SLinus Torvalds if (IS_ROOT(victim)) 14291da177e4SLinus Torvalds return -EBUSY; 14301da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 14311da177e4SLinus Torvalds return -EISDIR; 14321da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14331da177e4SLinus Torvalds return -ENOENT; 14341da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 14351da177e4SLinus Torvalds return -EBUSY; 14361da177e4SLinus Torvalds return 0; 14371da177e4SLinus Torvalds } 14381da177e4SLinus Torvalds 14391da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 14401da177e4SLinus Torvalds * dir. 14411da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 14421da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 14431da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 14441da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 14451da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 14461da177e4SLinus Torvalds */ 14471da177e4SLinus Torvalds static inline int may_create(struct inode *dir, struct dentry *child, 14481da177e4SLinus Torvalds struct nameidata *nd) 14491da177e4SLinus Torvalds { 14501da177e4SLinus Torvalds if (child->d_inode) 14511da177e4SLinus Torvalds return -EEXIST; 14521da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14531da177e4SLinus Torvalds return -ENOENT; 1454f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 14551da177e4SLinus Torvalds } 14561da177e4SLinus Torvalds 14571da177e4SLinus Torvalds /* 14581da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 14591da177e4SLinus Torvalds */ 14601da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 14611da177e4SLinus Torvalds { 14621da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 14631da177e4SLinus Torvalds 14641da177e4SLinus Torvalds if (f & O_NOFOLLOW) 14651da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 14661da177e4SLinus Torvalds 14671da177e4SLinus Torvalds if (f & O_DIRECTORY) 14681da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 14691da177e4SLinus Torvalds 14701da177e4SLinus Torvalds return retval; 14711da177e4SLinus Torvalds } 14721da177e4SLinus Torvalds 14731da177e4SLinus Torvalds /* 14741da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 14751da177e4SLinus Torvalds */ 14761da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 14771da177e4SLinus Torvalds { 14781da177e4SLinus Torvalds struct dentry *p; 14791da177e4SLinus Torvalds 14801da177e4SLinus Torvalds if (p1 == p2) { 1481f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 14821da177e4SLinus Torvalds return NULL; 14831da177e4SLinus Torvalds } 14841da177e4SLinus Torvalds 1485a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14861da177e4SLinus Torvalds 14871da177e4SLinus Torvalds for (p = p1; p->d_parent != p; p = p->d_parent) { 14881da177e4SLinus Torvalds if (p->d_parent == p2) { 1489f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1490f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 14911da177e4SLinus Torvalds return p; 14921da177e4SLinus Torvalds } 14931da177e4SLinus Torvalds } 14941da177e4SLinus Torvalds 14951da177e4SLinus Torvalds for (p = p2; p->d_parent != p; p = p->d_parent) { 14961da177e4SLinus Torvalds if (p->d_parent == p1) { 1497f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1498f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14991da177e4SLinus Torvalds return p; 15001da177e4SLinus Torvalds } 15011da177e4SLinus Torvalds } 15021da177e4SLinus Torvalds 1503f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1504f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 15051da177e4SLinus Torvalds return NULL; 15061da177e4SLinus Torvalds } 15071da177e4SLinus Torvalds 15081da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 15091da177e4SLinus Torvalds { 15101b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 15111da177e4SLinus Torvalds if (p1 != p2) { 15121b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1513a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 15141da177e4SLinus Torvalds } 15151da177e4SLinus Torvalds } 15161da177e4SLinus Torvalds 15171da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 15181da177e4SLinus Torvalds struct nameidata *nd) 15191da177e4SLinus Torvalds { 15201da177e4SLinus Torvalds int error = may_create(dir, dentry, nd); 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds if (error) 15231da177e4SLinus Torvalds return error; 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 15261da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 15271da177e4SLinus Torvalds mode &= S_IALLUGO; 15281da177e4SLinus Torvalds mode |= S_IFREG; 15291da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 15301da177e4SLinus Torvalds if (error) 15311da177e4SLinus Torvalds return error; 15321da177e4SLinus Torvalds DQUOT_INIT(dir); 15331da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1534a74574aaSStephen Smalley if (!error) 1535f38aa942SAmy Griffis fsnotify_create(dir, dentry); 15361da177e4SLinus Torvalds return error; 15371da177e4SLinus Torvalds } 15381da177e4SLinus Torvalds 15391da177e4SLinus Torvalds int may_open(struct nameidata *nd, int acc_mode, int flag) 15401da177e4SLinus Torvalds { 15414ac91378SJan Blunck struct dentry *dentry = nd->path.dentry; 15421da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 15431da177e4SLinus Torvalds int error; 15441da177e4SLinus Torvalds 15451da177e4SLinus Torvalds if (!inode) 15461da177e4SLinus Torvalds return -ENOENT; 15471da177e4SLinus Torvalds 15481da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 15491da177e4SLinus Torvalds return -ELOOP; 15501da177e4SLinus Torvalds 1551974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 15521da177e4SLinus Torvalds return -EISDIR; 15531da177e4SLinus Torvalds 15541da177e4SLinus Torvalds /* 15551da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 15561da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 15571da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 15581da177e4SLinus Torvalds */ 15591da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 15601da177e4SLinus Torvalds flag &= ~O_TRUNC; 15611da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 15624ac91378SJan Blunck if (nd->path.mnt->mnt_flags & MNT_NODEV) 15631da177e4SLinus Torvalds return -EACCES; 15641da177e4SLinus Torvalds 15651da177e4SLinus Torvalds flag &= ~O_TRUNC; 15664a3fd211SDave Hansen } 1567b41572e9SDave Hansen 1568b41572e9SDave Hansen error = vfs_permission(nd, acc_mode); 1569b41572e9SDave Hansen if (error) 1570b41572e9SDave Hansen return error; 15711da177e4SLinus Torvalds /* 15721da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 15731da177e4SLinus Torvalds */ 15741da177e4SLinus Torvalds if (IS_APPEND(inode)) { 15751da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 15761da177e4SLinus Torvalds return -EPERM; 15771da177e4SLinus Torvalds if (flag & O_TRUNC) 15781da177e4SLinus Torvalds return -EPERM; 15791da177e4SLinus Torvalds } 15801da177e4SLinus Torvalds 15811da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15821da177e4SLinus Torvalds if (flag & O_NOATIME) 15833bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 15841da177e4SLinus Torvalds return -EPERM; 15851da177e4SLinus Torvalds 15861da177e4SLinus Torvalds /* 15871da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15881da177e4SLinus Torvalds */ 15891da177e4SLinus Torvalds error = break_lease(inode, flag); 15901da177e4SLinus Torvalds if (error) 15911da177e4SLinus Torvalds return error; 15921da177e4SLinus Torvalds 15931da177e4SLinus Torvalds if (flag & O_TRUNC) { 15941da177e4SLinus Torvalds error = get_write_access(inode); 15951da177e4SLinus Torvalds if (error) 15961da177e4SLinus Torvalds return error; 15971da177e4SLinus Torvalds 15981da177e4SLinus Torvalds /* 15991da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 16001da177e4SLinus Torvalds */ 16011da177e4SLinus Torvalds error = locks_verify_locked(inode); 16021da177e4SLinus Torvalds if (!error) { 16031da177e4SLinus Torvalds DQUOT_INIT(inode); 16041da177e4SLinus Torvalds 1605d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1606d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1607d139d7ffSMiklos Szeredi NULL); 16081da177e4SLinus Torvalds } 16091da177e4SLinus Torvalds put_write_access(inode); 16101da177e4SLinus Torvalds if (error) 16111da177e4SLinus Torvalds return error; 16121da177e4SLinus Torvalds } else 16131da177e4SLinus Torvalds if (flag & FMODE_WRITE) 16141da177e4SLinus Torvalds DQUOT_INIT(inode); 16151da177e4SLinus Torvalds 16161da177e4SLinus Torvalds return 0; 16171da177e4SLinus Torvalds } 16181da177e4SLinus Torvalds 1619d57999e1SDave Hansen /* 1620d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1621d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1622d57999e1SDave Hansen * what get passed to sys_open(). 1623d57999e1SDave Hansen */ 1624d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1625aab520e2SDave Hansen int flag, int mode) 1626aab520e2SDave Hansen { 1627aab520e2SDave Hansen int error; 16284ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1629aab520e2SDave Hansen 1630aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1631aab520e2SDave Hansen mode &= ~current->fs->umask; 1632aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1633aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 16344ac91378SJan Blunck dput(nd->path.dentry); 16354ac91378SJan Blunck nd->path.dentry = path->dentry; 1636aab520e2SDave Hansen if (error) 1637aab520e2SDave Hansen return error; 1638aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 1639aab520e2SDave Hansen return may_open(nd, 0, flag & ~O_TRUNC); 1640aab520e2SDave Hansen } 1641aab520e2SDave Hansen 16421da177e4SLinus Torvalds /* 1643d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1644d57999e1SDave Hansen * 00 - read-only 1645d57999e1SDave Hansen * 01 - write-only 1646d57999e1SDave Hansen * 10 - read-write 1647d57999e1SDave Hansen * 11 - special 1648d57999e1SDave Hansen * it is changed into 1649d57999e1SDave Hansen * 00 - no permissions needed 1650d57999e1SDave Hansen * 01 - read-permission 1651d57999e1SDave Hansen * 10 - write-permission 1652d57999e1SDave Hansen * 11 - read-write 1653d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1654d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1655d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1656d57999e1SDave Hansen * later). 1657d57999e1SDave Hansen * 1658d57999e1SDave Hansen */ 1659d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1660d57999e1SDave Hansen { 1661d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1662d57999e1SDave Hansen flag++; 1663d57999e1SDave Hansen return flag; 1664d57999e1SDave Hansen } 1665d57999e1SDave Hansen 16664a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 16674a3fd211SDave Hansen { 1668d57999e1SDave Hansen /* 16694a3fd211SDave Hansen * We'll never write to the fs underlying 16704a3fd211SDave Hansen * a device file. 16714a3fd211SDave Hansen */ 16724a3fd211SDave Hansen if (special_file(inode->i_mode)) 16734a3fd211SDave Hansen return 0; 16744a3fd211SDave Hansen return (flag & O_TRUNC); 16754a3fd211SDave Hansen } 16764a3fd211SDave Hansen 16774a3fd211SDave Hansen /* 16784a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16794a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16804a3fd211SDave Hansen * open_to_namei_flags() for more details. 16811da177e4SLinus Torvalds */ 1682a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 1683a70e65dfSChristoph Hellwig int open_flag, int mode) 16841da177e4SLinus Torvalds { 16854a3fd211SDave Hansen struct file *filp; 1686a70e65dfSChristoph Hellwig struct nameidata nd; 1687834f2a4aSTrond Myklebust int acc_mode, error; 16884e7506e4SAl Viro struct path path; 16891da177e4SLinus Torvalds struct dentry *dir; 16901da177e4SLinus Torvalds int count = 0; 16914a3fd211SDave Hansen int will_write; 1692d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16931da177e4SLinus Torvalds 1694b77b0646SAl Viro acc_mode = MAY_OPEN | ACC_MODE(flag); 16951da177e4SLinus Torvalds 1696834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1697834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1698834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1699834f2a4aSTrond Myklebust 17001da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 17011da177e4SLinus Torvalds access from general write access. */ 17021da177e4SLinus Torvalds if (flag & O_APPEND) 17031da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 17041da177e4SLinus Torvalds 17051da177e4SLinus Torvalds /* 17061da177e4SLinus Torvalds * The simplest case - just a plain lookup. 17071da177e4SLinus Torvalds */ 17081da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 17095590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1710a70e65dfSChristoph Hellwig &nd, flag); 17111da177e4SLinus Torvalds if (error) 1712a70e65dfSChristoph Hellwig return ERR_PTR(error); 17131da177e4SLinus Torvalds goto ok; 17141da177e4SLinus Torvalds } 17151da177e4SLinus Torvalds 17161da177e4SLinus Torvalds /* 17171da177e4SLinus Torvalds * Create - we need to know the parent. 17181da177e4SLinus Torvalds */ 1719a70e65dfSChristoph Hellwig error = path_lookup_create(dfd, pathname, LOOKUP_PARENT, 1720a70e65dfSChristoph Hellwig &nd, flag, mode); 17211da177e4SLinus Torvalds if (error) 1722a70e65dfSChristoph Hellwig return ERR_PTR(error); 17231da177e4SLinus Torvalds 17241da177e4SLinus Torvalds /* 17251da177e4SLinus Torvalds * We have the parent and last component. First of all, check 17261da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 17271da177e4SLinus Torvalds * will not do. 17281da177e4SLinus Torvalds */ 17291da177e4SLinus Torvalds error = -EISDIR; 1730a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 17311da177e4SLinus Torvalds goto exit; 17321da177e4SLinus Torvalds 1733a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1734a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 17351b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1736a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1737a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 17381da177e4SLinus Torvalds 17391da177e4SLinus Torvalds do_last: 17404e7506e4SAl Viro error = PTR_ERR(path.dentry); 17414e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17421b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17431da177e4SLinus Torvalds goto exit; 17441da177e4SLinus Torvalds } 17451da177e4SLinus Torvalds 1746a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1747a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17484a3fd211SDave Hansen goto exit_mutex_unlock; 17494af4c52fSOleg Drokin } 17504af4c52fSOleg Drokin 17511da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17524e7506e4SAl Viro if (!path.dentry->d_inode) { 17534a3fd211SDave Hansen /* 17544a3fd211SDave Hansen * This write is needed to ensure that a 17554a3fd211SDave Hansen * ro->rw transition does not occur between 17564a3fd211SDave Hansen * the time when the file is created and when 17574a3fd211SDave Hansen * a permanent write count is taken through 17584a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17594a3fd211SDave Hansen */ 17604a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17611da177e4SLinus Torvalds if (error) 17624a3fd211SDave Hansen goto exit_mutex_unlock; 17634a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 17644a3fd211SDave Hansen if (error) { 17654a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17661da177e4SLinus Torvalds goto exit; 17674a3fd211SDave Hansen } 17684a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17694a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17704a3fd211SDave Hansen return filp; 17711da177e4SLinus Torvalds } 17721da177e4SLinus Torvalds 17731da177e4SLinus Torvalds /* 17741da177e4SLinus Torvalds * It already exists. 17751da177e4SLinus Torvalds */ 17761b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17775a190ae6SAl Viro audit_inode(pathname, path.dentry); 17781da177e4SLinus Torvalds 17791da177e4SLinus Torvalds error = -EEXIST; 17801da177e4SLinus Torvalds if (flag & O_EXCL) 17811da177e4SLinus Torvalds goto exit_dput; 17821da177e4SLinus Torvalds 1783e13b210fSAl Viro if (__follow_mount(&path)) { 17841da177e4SLinus Torvalds error = -ELOOP; 1785ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1786ba7a4c1aSAl Viro goto exit_dput; 17871da177e4SLinus Torvalds } 17883e2efce0SAmy Griffis 17891da177e4SLinus Torvalds error = -ENOENT; 17904e7506e4SAl Viro if (!path.dentry->d_inode) 17911da177e4SLinus Torvalds goto exit_dput; 17924e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 17931da177e4SLinus Torvalds goto do_link; 17941da177e4SLinus Torvalds 1795a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 17961da177e4SLinus Torvalds error = -EISDIR; 17974e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 17981da177e4SLinus Torvalds goto exit; 17991da177e4SLinus Torvalds ok: 18004a3fd211SDave Hansen /* 18014a3fd211SDave Hansen * Consider: 18024a3fd211SDave Hansen * 1. may_open() truncates a file 18034a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 18044a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 18054a3fd211SDave Hansen * the ro mount. 18064a3fd211SDave Hansen * That would be inconsistent, and should 18074a3fd211SDave Hansen * be avoided. Taking this mnt write here 18084a3fd211SDave Hansen * ensures that (2) can not occur. 18094a3fd211SDave Hansen */ 18104a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 18114a3fd211SDave Hansen if (will_write) { 18124a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 18131da177e4SLinus Torvalds if (error) 18141da177e4SLinus Torvalds goto exit; 18154a3fd211SDave Hansen } 18164a3fd211SDave Hansen error = may_open(&nd, acc_mode, flag); 18174a3fd211SDave Hansen if (error) { 18184a3fd211SDave Hansen if (will_write) 18194a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18204a3fd211SDave Hansen goto exit; 18214a3fd211SDave Hansen } 18224a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 18234a3fd211SDave Hansen /* 18244a3fd211SDave Hansen * It is now safe to drop the mnt write 18254a3fd211SDave Hansen * because the filp has had a write taken 18264a3fd211SDave Hansen * on its behalf. 18274a3fd211SDave Hansen */ 18284a3fd211SDave Hansen if (will_write) 18294a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18304a3fd211SDave Hansen return filp; 18311da177e4SLinus Torvalds 18324a3fd211SDave Hansen exit_mutex_unlock: 18334a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 18341da177e4SLinus Torvalds exit_dput: 1835a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 18361da177e4SLinus Torvalds exit: 1837a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1838a70e65dfSChristoph Hellwig release_open_intent(&nd); 1839a70e65dfSChristoph Hellwig path_put(&nd.path); 1840a70e65dfSChristoph Hellwig return ERR_PTR(error); 18411da177e4SLinus Torvalds 18421da177e4SLinus Torvalds do_link: 18431da177e4SLinus Torvalds error = -ELOOP; 18441da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18451da177e4SLinus Torvalds goto exit_dput; 18461da177e4SLinus Torvalds /* 18471da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18481da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18491da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18501da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18511da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18521da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18531da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18541da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18551da177e4SLinus Torvalds */ 1856a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1857a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18581da177e4SLinus Torvalds if (error) 18591da177e4SLinus Torvalds goto exit_dput; 1860a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1861de459215SKirill Korotaev if (error) { 1862de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1863de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1864de459215SKirill Korotaev * with "intent.open". 1865de459215SKirill Korotaev */ 1866a70e65dfSChristoph Hellwig release_open_intent(&nd); 1867a70e65dfSChristoph Hellwig return ERR_PTR(error); 1868de459215SKirill Korotaev } 1869a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1870a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18711da177e4SLinus Torvalds goto ok; 18721da177e4SLinus Torvalds error = -EISDIR; 1873a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18741da177e4SLinus Torvalds goto exit; 1875a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1876a70e65dfSChristoph Hellwig __putname(nd.last.name); 18771da177e4SLinus Torvalds goto exit; 18781da177e4SLinus Torvalds } 18791da177e4SLinus Torvalds error = -ELOOP; 18801da177e4SLinus Torvalds if (count++==32) { 1881a70e65dfSChristoph Hellwig __putname(nd.last.name); 18821da177e4SLinus Torvalds goto exit; 18831da177e4SLinus Torvalds } 1884a70e65dfSChristoph Hellwig dir = nd.path.dentry; 18851b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1886a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1887a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1888a70e65dfSChristoph Hellwig __putname(nd.last.name); 18891da177e4SLinus Torvalds goto do_last; 18901da177e4SLinus Torvalds } 18911da177e4SLinus Torvalds 18921da177e4SLinus Torvalds /** 1893a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1894a70e65dfSChristoph Hellwig * 1895a70e65dfSChristoph Hellwig * @filename: path to open 1896a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1897a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1898a70e65dfSChristoph Hellwig * 1899a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1900a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1901a70e65dfSChristoph Hellwig * along, nothing to see here.. 1902a70e65dfSChristoph Hellwig */ 1903a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1904a70e65dfSChristoph Hellwig { 1905a70e65dfSChristoph Hellwig return do_filp_open(AT_FDCWD, filename, flags, mode); 1906a70e65dfSChristoph Hellwig } 1907a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1908a70e65dfSChristoph Hellwig 1909a70e65dfSChristoph Hellwig /** 19101da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 19111da177e4SLinus Torvalds * @nd: nameidata info 19121da177e4SLinus Torvalds * @is_dir: directory flag 19131da177e4SLinus Torvalds * 19141da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 19151da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1916c663e5d8SChristoph Hellwig * 19174ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 19181da177e4SLinus Torvalds */ 19191da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 19201da177e4SLinus Torvalds { 1921c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 19221da177e4SLinus Torvalds 19234ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1924c663e5d8SChristoph Hellwig /* 1925c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1926c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1927c663e5d8SChristoph Hellwig */ 19281da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19291da177e4SLinus Torvalds goto fail; 19301da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 1931a634904aSASANO Masahiro nd->flags |= LOOKUP_CREATE; 1932a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1933c663e5d8SChristoph Hellwig 1934c663e5d8SChristoph Hellwig /* 1935c663e5d8SChristoph Hellwig * Do the final lookup. 1936c663e5d8SChristoph Hellwig */ 193749705b77SChristoph Hellwig dentry = lookup_hash(nd); 19381da177e4SLinus Torvalds if (IS_ERR(dentry)) 19391da177e4SLinus Torvalds goto fail; 1940c663e5d8SChristoph Hellwig 1941e9baf6e5SAl Viro if (dentry->d_inode) 1942e9baf6e5SAl Viro goto eexist; 1943c663e5d8SChristoph Hellwig /* 1944c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1945c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1946c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1947c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1948c663e5d8SChristoph Hellwig */ 1949e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19501da177e4SLinus Torvalds dput(dentry); 19511da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1952e9baf6e5SAl Viro } 1953e9baf6e5SAl Viro return dentry; 1954e9baf6e5SAl Viro eexist: 1955e9baf6e5SAl Viro dput(dentry); 1956e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19571da177e4SLinus Torvalds fail: 19581da177e4SLinus Torvalds return dentry; 19591da177e4SLinus Torvalds } 1960f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19611da177e4SLinus Torvalds 19621da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19631da177e4SLinus Torvalds { 19641da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 19651da177e4SLinus Torvalds 19661da177e4SLinus Torvalds if (error) 19671da177e4SLinus Torvalds return error; 19681da177e4SLinus Torvalds 19691da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19701da177e4SLinus Torvalds return -EPERM; 19711da177e4SLinus Torvalds 19721da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 19731da177e4SLinus Torvalds return -EPERM; 19741da177e4SLinus Torvalds 197508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 197608ce5f16SSerge E. Hallyn if (error) 197708ce5f16SSerge E. Hallyn return error; 197808ce5f16SSerge E. Hallyn 19791da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19801da177e4SLinus Torvalds if (error) 19811da177e4SLinus Torvalds return error; 19821da177e4SLinus Torvalds 19831da177e4SLinus Torvalds DQUOT_INIT(dir); 19841da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1985a74574aaSStephen Smalley if (!error) 1986f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19871da177e4SLinus Torvalds return error; 19881da177e4SLinus Torvalds } 19891da177e4SLinus Torvalds 1990463c3197SDave Hansen static int may_mknod(mode_t mode) 1991463c3197SDave Hansen { 1992463c3197SDave Hansen switch (mode & S_IFMT) { 1993463c3197SDave Hansen case S_IFREG: 1994463c3197SDave Hansen case S_IFCHR: 1995463c3197SDave Hansen case S_IFBLK: 1996463c3197SDave Hansen case S_IFIFO: 1997463c3197SDave Hansen case S_IFSOCK: 1998463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 1999463c3197SDave Hansen return 0; 2000463c3197SDave Hansen case S_IFDIR: 2001463c3197SDave Hansen return -EPERM; 2002463c3197SDave Hansen default: 2003463c3197SDave Hansen return -EINVAL; 2004463c3197SDave Hansen } 2005463c3197SDave Hansen } 2006463c3197SDave Hansen 20075590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 20085590ff0dSUlrich Drepper unsigned dev) 20091da177e4SLinus Torvalds { 20102ad94ae6SAl Viro int error; 20111da177e4SLinus Torvalds char *tmp; 20121da177e4SLinus Torvalds struct dentry *dentry; 20131da177e4SLinus Torvalds struct nameidata nd; 20141da177e4SLinus Torvalds 20151da177e4SLinus Torvalds if (S_ISDIR(mode)) 20161da177e4SLinus Torvalds return -EPERM; 20171da177e4SLinus Torvalds 20182ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 20191da177e4SLinus Torvalds if (error) 20202ad94ae6SAl Viro return error; 20212ad94ae6SAl Viro 20221da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2023463c3197SDave Hansen if (IS_ERR(dentry)) { 20241da177e4SLinus Torvalds error = PTR_ERR(dentry); 2025463c3197SDave Hansen goto out_unlock; 2026463c3197SDave Hansen } 20274ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20281da177e4SLinus Torvalds mode &= ~current->fs->umask; 2029463c3197SDave Hansen error = may_mknod(mode); 2030463c3197SDave Hansen if (error) 2031463c3197SDave Hansen goto out_dput; 2032463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2033463c3197SDave Hansen if (error) 2034463c3197SDave Hansen goto out_dput; 20351da177e4SLinus Torvalds switch (mode & S_IFMT) { 20361da177e4SLinus Torvalds case 0: case S_IFREG: 20374ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20381da177e4SLinus Torvalds break; 20391da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20404ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20411da177e4SLinus Torvalds new_decode_dev(dev)); 20421da177e4SLinus Torvalds break; 20431da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20444ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20451da177e4SLinus Torvalds break; 20461da177e4SLinus Torvalds } 2047463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2048463c3197SDave Hansen out_dput: 20491da177e4SLinus Torvalds dput(dentry); 2050463c3197SDave Hansen out_unlock: 20514ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20521d957f9bSJan Blunck path_put(&nd.path); 20531da177e4SLinus Torvalds putname(tmp); 20541da177e4SLinus Torvalds 20551da177e4SLinus Torvalds return error; 20561da177e4SLinus Torvalds } 20571da177e4SLinus Torvalds 20585590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 20595590ff0dSUlrich Drepper { 20605590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20615590ff0dSUlrich Drepper } 20625590ff0dSUlrich Drepper 20631da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20641da177e4SLinus Torvalds { 20651da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 20661da177e4SLinus Torvalds 20671da177e4SLinus Torvalds if (error) 20681da177e4SLinus Torvalds return error; 20691da177e4SLinus Torvalds 20701da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 20711da177e4SLinus Torvalds return -EPERM; 20721da177e4SLinus Torvalds 20731da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20741da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20751da177e4SLinus Torvalds if (error) 20761da177e4SLinus Torvalds return error; 20771da177e4SLinus Torvalds 20781da177e4SLinus Torvalds DQUOT_INIT(dir); 20791da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2080a74574aaSStephen Smalley if (!error) 2081f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20821da177e4SLinus Torvalds return error; 20831da177e4SLinus Torvalds } 20841da177e4SLinus Torvalds 20855590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 20861da177e4SLinus Torvalds { 20871da177e4SLinus Torvalds int error = 0; 20881da177e4SLinus Torvalds char * tmp; 20896902d925SDave Hansen struct dentry *dentry; 20906902d925SDave Hansen struct nameidata nd; 20911da177e4SLinus Torvalds 20922ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 20932ad94ae6SAl Viro if (error) 20946902d925SDave Hansen goto out_err; 20951da177e4SLinus Torvalds 20961da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20971da177e4SLinus Torvalds error = PTR_ERR(dentry); 20986902d925SDave Hansen if (IS_ERR(dentry)) 20996902d925SDave Hansen goto out_unlock; 21006902d925SDave Hansen 21014ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 21021da177e4SLinus Torvalds mode &= ~current->fs->umask; 2103463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2104463c3197SDave Hansen if (error) 2105463c3197SDave Hansen goto out_dput; 21064ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2107463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2108463c3197SDave Hansen out_dput: 21091da177e4SLinus Torvalds dput(dentry); 21106902d925SDave Hansen out_unlock: 21114ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21121d957f9bSJan Blunck path_put(&nd.path); 21131da177e4SLinus Torvalds putname(tmp); 21146902d925SDave Hansen out_err: 21151da177e4SLinus Torvalds return error; 21161da177e4SLinus Torvalds } 21171da177e4SLinus Torvalds 21185590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 21195590ff0dSUlrich Drepper { 21205590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 21215590ff0dSUlrich Drepper } 21225590ff0dSUlrich Drepper 21231da177e4SLinus Torvalds /* 21241da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21251da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21261da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 21271da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21281da177e4SLinus Torvalds * 21291da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21301da177e4SLinus Torvalds * do a 21311da177e4SLinus Torvalds * 21321da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21331da177e4SLinus Torvalds * return -EBUSY; 21341da177e4SLinus Torvalds * 21351da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21361da177e4SLinus Torvalds * that is still in use by something else.. 21371da177e4SLinus Torvalds */ 21381da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21391da177e4SLinus Torvalds { 21401da177e4SLinus Torvalds dget(dentry); 21411da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21421da177e4SLinus Torvalds spin_lock(&dcache_lock); 21431da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21441da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21451da177e4SLinus Torvalds __d_drop(dentry); 21461da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21471da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21481da177e4SLinus Torvalds } 21491da177e4SLinus Torvalds 21501da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21511da177e4SLinus Torvalds { 21521da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21531da177e4SLinus Torvalds 21541da177e4SLinus Torvalds if (error) 21551da177e4SLinus Torvalds return error; 21561da177e4SLinus Torvalds 21571da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 21581da177e4SLinus Torvalds return -EPERM; 21591da177e4SLinus Torvalds 21601da177e4SLinus Torvalds DQUOT_INIT(dir); 21611da177e4SLinus Torvalds 21621b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21631da177e4SLinus Torvalds dentry_unhash(dentry); 21641da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21651da177e4SLinus Torvalds error = -EBUSY; 21661da177e4SLinus Torvalds else { 21671da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21681da177e4SLinus Torvalds if (!error) { 21691da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21701da177e4SLinus Torvalds if (!error) 21711da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21721da177e4SLinus Torvalds } 21731da177e4SLinus Torvalds } 21741b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21751da177e4SLinus Torvalds if (!error) { 21761da177e4SLinus Torvalds d_delete(dentry); 21771da177e4SLinus Torvalds } 21781da177e4SLinus Torvalds dput(dentry); 21791da177e4SLinus Torvalds 21801da177e4SLinus Torvalds return error; 21811da177e4SLinus Torvalds } 21821da177e4SLinus Torvalds 21835590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21841da177e4SLinus Torvalds { 21851da177e4SLinus Torvalds int error = 0; 21861da177e4SLinus Torvalds char * name; 21871da177e4SLinus Torvalds struct dentry *dentry; 21881da177e4SLinus Torvalds struct nameidata nd; 21891da177e4SLinus Torvalds 21902ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 21911da177e4SLinus Torvalds if (error) 21922ad94ae6SAl Viro return error; 21931da177e4SLinus Torvalds 21941da177e4SLinus Torvalds switch(nd.last_type) { 21951da177e4SLinus Torvalds case LAST_DOTDOT: 21961da177e4SLinus Torvalds error = -ENOTEMPTY; 21971da177e4SLinus Torvalds goto exit1; 21981da177e4SLinus Torvalds case LAST_DOT: 21991da177e4SLinus Torvalds error = -EINVAL; 22001da177e4SLinus Torvalds goto exit1; 22011da177e4SLinus Torvalds case LAST_ROOT: 22021da177e4SLinus Torvalds error = -EBUSY; 22031da177e4SLinus Torvalds goto exit1; 22041da177e4SLinus Torvalds } 22054ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 220649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22071da177e4SLinus Torvalds error = PTR_ERR(dentry); 22086902d925SDave Hansen if (IS_ERR(dentry)) 22096902d925SDave Hansen goto exit2; 22100622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22110622753bSDave Hansen if (error) 22120622753bSDave Hansen goto exit3; 22134ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 22140622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22150622753bSDave Hansen exit3: 22161da177e4SLinus Torvalds dput(dentry); 22176902d925SDave Hansen exit2: 22184ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22191da177e4SLinus Torvalds exit1: 22201d957f9bSJan Blunck path_put(&nd.path); 22211da177e4SLinus Torvalds putname(name); 22221da177e4SLinus Torvalds return error; 22231da177e4SLinus Torvalds } 22241da177e4SLinus Torvalds 22255590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 22265590ff0dSUlrich Drepper { 22275590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22285590ff0dSUlrich Drepper } 22295590ff0dSUlrich Drepper 22301da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22311da177e4SLinus Torvalds { 22321da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22331da177e4SLinus Torvalds 22341da177e4SLinus Torvalds if (error) 22351da177e4SLinus Torvalds return error; 22361da177e4SLinus Torvalds 22371da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 22381da177e4SLinus Torvalds return -EPERM; 22391da177e4SLinus Torvalds 22401da177e4SLinus Torvalds DQUOT_INIT(dir); 22411da177e4SLinus Torvalds 22421b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22431da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22441da177e4SLinus Torvalds error = -EBUSY; 22451da177e4SLinus Torvalds else { 22461da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22471da177e4SLinus Torvalds if (!error) 22481da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22491da177e4SLinus Torvalds } 22501b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22511da177e4SLinus Torvalds 22521da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22531da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2254ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22551da177e4SLinus Torvalds d_delete(dentry); 22561da177e4SLinus Torvalds } 22570eeca283SRobert Love 22581da177e4SLinus Torvalds return error; 22591da177e4SLinus Torvalds } 22601da177e4SLinus Torvalds 22611da177e4SLinus Torvalds /* 22621da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22631b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22641da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22651da177e4SLinus Torvalds * while waiting on the I/O. 22661da177e4SLinus Torvalds */ 22675590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22681da177e4SLinus Torvalds { 22692ad94ae6SAl Viro int error; 22701da177e4SLinus Torvalds char *name; 22711da177e4SLinus Torvalds struct dentry *dentry; 22721da177e4SLinus Torvalds struct nameidata nd; 22731da177e4SLinus Torvalds struct inode *inode = NULL; 22741da177e4SLinus Torvalds 22752ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22761da177e4SLinus Torvalds if (error) 22772ad94ae6SAl Viro return error; 22782ad94ae6SAl Viro 22791da177e4SLinus Torvalds error = -EISDIR; 22801da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22811da177e4SLinus Torvalds goto exit1; 22824ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 228349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22841da177e4SLinus Torvalds error = PTR_ERR(dentry); 22851da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22861da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 22871da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 22881da177e4SLinus Torvalds goto slashes; 22891da177e4SLinus Torvalds inode = dentry->d_inode; 22901da177e4SLinus Torvalds if (inode) 22911da177e4SLinus Torvalds atomic_inc(&inode->i_count); 22920622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22930622753bSDave Hansen if (error) 22940622753bSDave Hansen goto exit2; 22954ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 22960622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22971da177e4SLinus Torvalds exit2: 22981da177e4SLinus Torvalds dput(dentry); 22991da177e4SLinus Torvalds } 23004ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23011da177e4SLinus Torvalds if (inode) 23021da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 23031da177e4SLinus Torvalds exit1: 23041d957f9bSJan Blunck path_put(&nd.path); 23051da177e4SLinus Torvalds putname(name); 23061da177e4SLinus Torvalds return error; 23071da177e4SLinus Torvalds 23081da177e4SLinus Torvalds slashes: 23091da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 23101da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 23111da177e4SLinus Torvalds goto exit2; 23121da177e4SLinus Torvalds } 23131da177e4SLinus Torvalds 23145590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 23155590ff0dSUlrich Drepper { 23165590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23175590ff0dSUlrich Drepper return -EINVAL; 23185590ff0dSUlrich Drepper 23195590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23205590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23215590ff0dSUlrich Drepper 23225590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23235590ff0dSUlrich Drepper } 23245590ff0dSUlrich Drepper 23255590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 23265590ff0dSUlrich Drepper { 23275590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23285590ff0dSUlrich Drepper } 23295590ff0dSUlrich Drepper 2330db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23311da177e4SLinus Torvalds { 23321da177e4SLinus Torvalds int error = may_create(dir, dentry, NULL); 23331da177e4SLinus Torvalds 23341da177e4SLinus Torvalds if (error) 23351da177e4SLinus Torvalds return error; 23361da177e4SLinus Torvalds 23371da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 23381da177e4SLinus Torvalds return -EPERM; 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23411da177e4SLinus Torvalds if (error) 23421da177e4SLinus Torvalds return error; 23431da177e4SLinus Torvalds 23441da177e4SLinus Torvalds DQUOT_INIT(dir); 23451da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2346a74574aaSStephen Smalley if (!error) 2347f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23481da177e4SLinus Torvalds return error; 23491da177e4SLinus Torvalds } 23501da177e4SLinus Torvalds 23515590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 23525590ff0dSUlrich Drepper int newdfd, const char __user *newname) 23531da177e4SLinus Torvalds { 23542ad94ae6SAl Viro int error; 23551da177e4SLinus Torvalds char *from; 23561da177e4SLinus Torvalds char *to; 23576902d925SDave Hansen struct dentry *dentry; 23586902d925SDave Hansen struct nameidata nd; 23591da177e4SLinus Torvalds 23601da177e4SLinus Torvalds from = getname(oldname); 23611da177e4SLinus Torvalds if (IS_ERR(from)) 23621da177e4SLinus Torvalds return PTR_ERR(from); 23632ad94ae6SAl Viro 23642ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 23652ad94ae6SAl Viro if (error) 23666902d925SDave Hansen goto out_putname; 23671da177e4SLinus Torvalds 23681da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23691da177e4SLinus Torvalds error = PTR_ERR(dentry); 23706902d925SDave Hansen if (IS_ERR(dentry)) 23716902d925SDave Hansen goto out_unlock; 23726902d925SDave Hansen 237375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 237475c3f29dSDave Hansen if (error) 237575c3f29dSDave Hansen goto out_dput; 2376db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 237775c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 237875c3f29dSDave Hansen out_dput: 23791da177e4SLinus Torvalds dput(dentry); 23806902d925SDave Hansen out_unlock: 23814ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23821d957f9bSJan Blunck path_put(&nd.path); 23831da177e4SLinus Torvalds putname(to); 23846902d925SDave Hansen out_putname: 23851da177e4SLinus Torvalds putname(from); 23861da177e4SLinus Torvalds return error; 23871da177e4SLinus Torvalds } 23881da177e4SLinus Torvalds 23895590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 23905590ff0dSUlrich Drepper { 23915590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 23925590ff0dSUlrich Drepper } 23935590ff0dSUlrich Drepper 23941da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 23951da177e4SLinus Torvalds { 23961da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 23971da177e4SLinus Torvalds int error; 23981da177e4SLinus Torvalds 23991da177e4SLinus Torvalds if (!inode) 24001da177e4SLinus Torvalds return -ENOENT; 24011da177e4SLinus Torvalds 24021da177e4SLinus Torvalds error = may_create(dir, new_dentry, NULL); 24031da177e4SLinus Torvalds if (error) 24041da177e4SLinus Torvalds return error; 24051da177e4SLinus Torvalds 24061da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 24071da177e4SLinus Torvalds return -EXDEV; 24081da177e4SLinus Torvalds 24091da177e4SLinus Torvalds /* 24101da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24111da177e4SLinus Torvalds */ 24121da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24131da177e4SLinus Torvalds return -EPERM; 24141da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 24151da177e4SLinus Torvalds return -EPERM; 24167e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24171da177e4SLinus Torvalds return -EPERM; 24181da177e4SLinus Torvalds 24191da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24201da177e4SLinus Torvalds if (error) 24211da177e4SLinus Torvalds return error; 24221da177e4SLinus Torvalds 24237e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24241da177e4SLinus Torvalds DQUOT_INIT(dir); 24251da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24267e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2427e31e14ecSStephen Smalley if (!error) 24287e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24291da177e4SLinus Torvalds return error; 24301da177e4SLinus Torvalds } 24311da177e4SLinus Torvalds 24321da177e4SLinus Torvalds /* 24331da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24341da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24351da177e4SLinus Torvalds * newname. --KAB 24361da177e4SLinus Torvalds * 24371da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24381da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24391da177e4SLinus Torvalds * and other special files. --ADM 24401da177e4SLinus Torvalds */ 24415590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2442c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2443c04030e1SUlrich Drepper int flags) 24441da177e4SLinus Torvalds { 24451da177e4SLinus Torvalds struct dentry *new_dentry; 24462d8f3038SAl Viro struct nameidata nd; 24472d8f3038SAl Viro struct path old_path; 24481da177e4SLinus Torvalds int error; 24491da177e4SLinus Torvalds char *to; 24501da177e4SLinus Torvalds 245145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2452c04030e1SUlrich Drepper return -EINVAL; 2453c04030e1SUlrich Drepper 24542d8f3038SAl Viro error = user_path_at(olddfd, oldname, 245545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24562d8f3038SAl Viro &old_path); 24571da177e4SLinus Torvalds if (error) 24582ad94ae6SAl Viro return error; 24592ad94ae6SAl Viro 24602ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24611da177e4SLinus Torvalds if (error) 24621da177e4SLinus Torvalds goto out; 24631da177e4SLinus Torvalds error = -EXDEV; 24642d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 24651da177e4SLinus Torvalds goto out_release; 24661da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24671da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24686902d925SDave Hansen if (IS_ERR(new_dentry)) 24696902d925SDave Hansen goto out_unlock; 247075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 247175c3f29dSDave Hansen if (error) 247275c3f29dSDave Hansen goto out_dput; 24732d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 247475c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 247575c3f29dSDave Hansen out_dput: 24761da177e4SLinus Torvalds dput(new_dentry); 24776902d925SDave Hansen out_unlock: 24784ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24791da177e4SLinus Torvalds out_release: 24801d957f9bSJan Blunck path_put(&nd.path); 24812ad94ae6SAl Viro putname(to); 24821da177e4SLinus Torvalds out: 24832d8f3038SAl Viro path_put(&old_path); 24841da177e4SLinus Torvalds 24851da177e4SLinus Torvalds return error; 24861da177e4SLinus Torvalds } 24871da177e4SLinus Torvalds 24885590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 24895590ff0dSUlrich Drepper { 2490c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 24915590ff0dSUlrich Drepper } 24925590ff0dSUlrich Drepper 24931da177e4SLinus Torvalds /* 24941da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 24951da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 24961da177e4SLinus Torvalds * Problems: 24971da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 24981da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 24991da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2500a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 25011da177e4SLinus Torvalds * story. 25021da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 25031b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 25041da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 25051da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2506a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25071da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25081da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25091da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2510a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 25111da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25121da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25131da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25141da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25151da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25161da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25171da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25181da177e4SLinus Torvalds * trick as in rmdir(). 25191da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25201b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25211da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25221b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25231da177e4SLinus Torvalds * locking]. 25241da177e4SLinus Torvalds */ 252575c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25261da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25271da177e4SLinus Torvalds { 25281da177e4SLinus Torvalds int error = 0; 25291da177e4SLinus Torvalds struct inode *target; 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds /* 25321da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25331da177e4SLinus Torvalds * we'll need to flip '..'. 25341da177e4SLinus Torvalds */ 25351da177e4SLinus Torvalds if (new_dir != old_dir) { 2536f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25371da177e4SLinus Torvalds if (error) 25381da177e4SLinus Torvalds return error; 25391da177e4SLinus Torvalds } 25401da177e4SLinus Torvalds 25411da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25421da177e4SLinus Torvalds if (error) 25431da177e4SLinus Torvalds return error; 25441da177e4SLinus Torvalds 25451da177e4SLinus Torvalds target = new_dentry->d_inode; 25461da177e4SLinus Torvalds if (target) { 25471b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25481da177e4SLinus Torvalds dentry_unhash(new_dentry); 25491da177e4SLinus Torvalds } 25501da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25511da177e4SLinus Torvalds error = -EBUSY; 25521da177e4SLinus Torvalds else 25531da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25541da177e4SLinus Torvalds if (target) { 25551da177e4SLinus Torvalds if (!error) 25561da177e4SLinus Torvalds target->i_flags |= S_DEAD; 25571b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25581da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 25591da177e4SLinus Torvalds d_rehash(new_dentry); 25601da177e4SLinus Torvalds dput(new_dentry); 25611da177e4SLinus Torvalds } 2562e31e14ecSStephen Smalley if (!error) 2563349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25641da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25651da177e4SLinus Torvalds return error; 25661da177e4SLinus Torvalds } 25671da177e4SLinus Torvalds 256875c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25691da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25701da177e4SLinus Torvalds { 25711da177e4SLinus Torvalds struct inode *target; 25721da177e4SLinus Torvalds int error; 25731da177e4SLinus Torvalds 25741da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25751da177e4SLinus Torvalds if (error) 25761da177e4SLinus Torvalds return error; 25771da177e4SLinus Torvalds 25781da177e4SLinus Torvalds dget(new_dentry); 25791da177e4SLinus Torvalds target = new_dentry->d_inode; 25801da177e4SLinus Torvalds if (target) 25811b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25821da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25831da177e4SLinus Torvalds error = -EBUSY; 25841da177e4SLinus Torvalds else 25851da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25861da177e4SLinus Torvalds if (!error) { 2587349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25881da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 25891da177e4SLinus Torvalds } 25901da177e4SLinus Torvalds if (target) 25911b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25921da177e4SLinus Torvalds dput(new_dentry); 25931da177e4SLinus Torvalds return error; 25941da177e4SLinus Torvalds } 25951da177e4SLinus Torvalds 25961da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 25971da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25981da177e4SLinus Torvalds { 25991da177e4SLinus Torvalds int error; 26001da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 26010eeca283SRobert Love const char *old_name; 26021da177e4SLinus Torvalds 26031da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 26041da177e4SLinus Torvalds return 0; 26051da177e4SLinus Torvalds 26061da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26071da177e4SLinus Torvalds if (error) 26081da177e4SLinus Torvalds return error; 26091da177e4SLinus Torvalds 26101da177e4SLinus Torvalds if (!new_dentry->d_inode) 26111da177e4SLinus Torvalds error = may_create(new_dir, new_dentry, NULL); 26121da177e4SLinus Torvalds else 26131da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26141da177e4SLinus Torvalds if (error) 26151da177e4SLinus Torvalds return error; 26161da177e4SLinus Torvalds 26171da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 26181da177e4SLinus Torvalds return -EPERM; 26191da177e4SLinus Torvalds 26201da177e4SLinus Torvalds DQUOT_INIT(old_dir); 26211da177e4SLinus Torvalds DQUOT_INIT(new_dir); 26221da177e4SLinus Torvalds 26230eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26240eeca283SRobert Love 26251da177e4SLinus Torvalds if (is_dir) 26261da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26271da177e4SLinus Torvalds else 26281da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26291da177e4SLinus Torvalds if (!error) { 26300eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 263189204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26325a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26331da177e4SLinus Torvalds } 26340eeca283SRobert Love fsnotify_oldname_free(old_name); 26350eeca283SRobert Love 26361da177e4SLinus Torvalds return error; 26371da177e4SLinus Torvalds } 26381da177e4SLinus Torvalds 26392ad94ae6SAl Viro asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 26402ad94ae6SAl Viro int newdfd, const char __user *newname) 26411da177e4SLinus Torvalds { 26421da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26431da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26441da177e4SLinus Torvalds struct dentry *trap; 26451da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26462ad94ae6SAl Viro char *from; 26472ad94ae6SAl Viro char *to; 26482ad94ae6SAl Viro int error; 26491da177e4SLinus Torvalds 26502ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26511da177e4SLinus Torvalds if (error) 26521da177e4SLinus Torvalds goto exit; 26531da177e4SLinus Torvalds 26542ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 26551da177e4SLinus Torvalds if (error) 26561da177e4SLinus Torvalds goto exit1; 26571da177e4SLinus Torvalds 26581da177e4SLinus Torvalds error = -EXDEV; 26594ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 26601da177e4SLinus Torvalds goto exit2; 26611da177e4SLinus Torvalds 26624ac91378SJan Blunck old_dir = oldnd.path.dentry; 26631da177e4SLinus Torvalds error = -EBUSY; 26641da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 26651da177e4SLinus Torvalds goto exit2; 26661da177e4SLinus Torvalds 26674ac91378SJan Blunck new_dir = newnd.path.dentry; 26681da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26691da177e4SLinus Torvalds goto exit2; 26701da177e4SLinus Torvalds 26711da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 26721da177e4SLinus Torvalds 267349705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 26741da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 26751da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 26761da177e4SLinus Torvalds goto exit3; 26771da177e4SLinus Torvalds /* source must exist */ 26781da177e4SLinus Torvalds error = -ENOENT; 26791da177e4SLinus Torvalds if (!old_dentry->d_inode) 26801da177e4SLinus Torvalds goto exit4; 26811da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 26821da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 26831da177e4SLinus Torvalds error = -ENOTDIR; 26841da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 26851da177e4SLinus Torvalds goto exit4; 26861da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 26871da177e4SLinus Torvalds goto exit4; 26881da177e4SLinus Torvalds } 26891da177e4SLinus Torvalds /* source should not be ancestor of target */ 26901da177e4SLinus Torvalds error = -EINVAL; 26911da177e4SLinus Torvalds if (old_dentry == trap) 26921da177e4SLinus Torvalds goto exit4; 269349705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 26941da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 26951da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 26961da177e4SLinus Torvalds goto exit4; 26971da177e4SLinus Torvalds /* target should not be an ancestor of source */ 26981da177e4SLinus Torvalds error = -ENOTEMPTY; 26991da177e4SLinus Torvalds if (new_dentry == trap) 27001da177e4SLinus Torvalds goto exit5; 27011da177e4SLinus Torvalds 27029079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27039079b1ebSDave Hansen if (error) 27049079b1ebSDave Hansen goto exit5; 27051da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27061da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 27079079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27081da177e4SLinus Torvalds exit5: 27091da177e4SLinus Torvalds dput(new_dentry); 27101da177e4SLinus Torvalds exit4: 27111da177e4SLinus Torvalds dput(old_dentry); 27121da177e4SLinus Torvalds exit3: 27131da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27141da177e4SLinus Torvalds exit2: 27151d957f9bSJan Blunck path_put(&newnd.path); 27162ad94ae6SAl Viro putname(to); 27171da177e4SLinus Torvalds exit1: 27181d957f9bSJan Blunck path_put(&oldnd.path); 27191da177e4SLinus Torvalds putname(from); 27202ad94ae6SAl Viro exit: 27211da177e4SLinus Torvalds return error; 27221da177e4SLinus Torvalds } 27231da177e4SLinus Torvalds 27245590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 27255590ff0dSUlrich Drepper { 27265590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27275590ff0dSUlrich Drepper } 27285590ff0dSUlrich Drepper 27291da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27301da177e4SLinus Torvalds { 27311da177e4SLinus Torvalds int len; 27321da177e4SLinus Torvalds 27331da177e4SLinus Torvalds len = PTR_ERR(link); 27341da177e4SLinus Torvalds if (IS_ERR(link)) 27351da177e4SLinus Torvalds goto out; 27361da177e4SLinus Torvalds 27371da177e4SLinus Torvalds len = strlen(link); 27381da177e4SLinus Torvalds if (len > (unsigned) buflen) 27391da177e4SLinus Torvalds len = buflen; 27401da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27411da177e4SLinus Torvalds len = -EFAULT; 27421da177e4SLinus Torvalds out: 27431da177e4SLinus Torvalds return len; 27441da177e4SLinus Torvalds } 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds /* 27471da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 27481da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 27491da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 27501da177e4SLinus Torvalds */ 27511da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27521da177e4SLinus Torvalds { 27531da177e4SLinus Torvalds struct nameidata nd; 2754cc314eefSLinus Torvalds void *cookie; 2755694a1764SMarcin Slusarz int res; 2756cc314eefSLinus Torvalds 27571da177e4SLinus Torvalds nd.depth = 0; 2758cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2759694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2760694a1764SMarcin Slusarz return PTR_ERR(cookie); 2761694a1764SMarcin Slusarz 2762694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27631da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2764cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2765694a1764SMarcin Slusarz return res; 27661da177e4SLinus Torvalds } 27671da177e4SLinus Torvalds 27681da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 27691da177e4SLinus Torvalds { 27701da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 27711da177e4SLinus Torvalds } 27721da177e4SLinus Torvalds 27731da177e4SLinus Torvalds /* get the link contents into pagecache */ 27741da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 27751da177e4SLinus Torvalds { 27761da177e4SLinus Torvalds struct page * page; 27771da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2778090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 27791da177e4SLinus Torvalds if (IS_ERR(page)) 27806fe6900eSNick Piggin return (char*)page; 27811da177e4SLinus Torvalds *ppage = page; 27821da177e4SLinus Torvalds return kmap(page); 27831da177e4SLinus Torvalds } 27841da177e4SLinus Torvalds 27851da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27861da177e4SLinus Torvalds { 27871da177e4SLinus Torvalds struct page *page = NULL; 27881da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 27891da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 27901da177e4SLinus Torvalds if (page) { 27911da177e4SLinus Torvalds kunmap(page); 27921da177e4SLinus Torvalds page_cache_release(page); 27931da177e4SLinus Torvalds } 27941da177e4SLinus Torvalds return res; 27951da177e4SLinus Torvalds } 27961da177e4SLinus Torvalds 2797cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 27981da177e4SLinus Torvalds { 2799cc314eefSLinus Torvalds struct page *page = NULL; 28001da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2801cc314eefSLinus Torvalds return page; 28021da177e4SLinus Torvalds } 28031da177e4SLinus Torvalds 2804cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28051da177e4SLinus Torvalds { 2806cc314eefSLinus Torvalds struct page *page = cookie; 2807cc314eefSLinus Torvalds 2808cc314eefSLinus Torvalds if (page) { 28091da177e4SLinus Torvalds kunmap(page); 28101da177e4SLinus Torvalds page_cache_release(page); 28111da177e4SLinus Torvalds } 28121da177e4SLinus Torvalds } 28131da177e4SLinus Torvalds 28140adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 28150adb25d2SKirill Korotaev gfp_t gfp_mask) 28161da177e4SLinus Torvalds { 28171da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28180adb25d2SKirill Korotaev struct page *page; 2819afddba49SNick Piggin void *fsdata; 2820beb497abSDmitriy Monakhov int err; 28211da177e4SLinus Torvalds char *kaddr; 28221da177e4SLinus Torvalds 28237e53cac4SNeilBrown retry: 2824afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2825afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 28261da177e4SLinus Torvalds if (err) 2827afddba49SNick Piggin goto fail; 2828afddba49SNick Piggin 28291da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28301da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28311da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2832afddba49SNick Piggin 2833afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2834afddba49SNick Piggin page, fsdata); 28351da177e4SLinus Torvalds if (err < 0) 28361da177e4SLinus Torvalds goto fail; 2837afddba49SNick Piggin if (err < len-1) 2838afddba49SNick Piggin goto retry; 2839afddba49SNick Piggin 28401da177e4SLinus Torvalds mark_inode_dirty(inode); 28411da177e4SLinus Torvalds return 0; 28421da177e4SLinus Torvalds fail: 28431da177e4SLinus Torvalds return err; 28441da177e4SLinus Torvalds } 28451da177e4SLinus Torvalds 28460adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 28470adb25d2SKirill Korotaev { 28480adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 28490adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 28500adb25d2SKirill Korotaev } 28510adb25d2SKirill Korotaev 285292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 28531da177e4SLinus Torvalds .readlink = generic_readlink, 28541da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28551da177e4SLinus Torvalds .put_link = page_put_link, 28561da177e4SLinus Torvalds }; 28571da177e4SLinus Torvalds 28582d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 28591da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 28601da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 28611da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 28621da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 28631da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 28641da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 28651da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 28661da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 28671da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 28680adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 28691da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 28701da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 28711da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 287216f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2873f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 2874e4543eddSChristoph Hellwig EXPORT_SYMBOL(vfs_permission); 28758c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 28761da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 28771da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 28781da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 28791da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 28801da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 28811da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 28821da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 28831da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 28841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 28851da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 28861da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 28871da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 28881da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 28891da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2890