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> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 351da177e4SLinus Torvalds #include <asm/uaccess.h> 361da177e4SLinus Torvalds 371da177e4SLinus Torvalds #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) 381da177e4SLinus Torvalds 391da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 401da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 411da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 421da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 431da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 461da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 471da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 481da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 491da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 501da177e4SLinus Torvalds * the special cases of the former code. 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 531da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 541da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 571da177e4SLinus Torvalds * resolution to correspond with current state of the code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 601da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 611da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 621da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 631da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 641da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 651da177e4SLinus Torvalds */ 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 681da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 691da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 701da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 711da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 721da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 731da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 110a02f76c3SAl Viro static int __link_path_walk(const char *name, struct nameidata *nd); 111c4a7808fSJosef 'Jeff' Sipek 1121da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1131da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1141da177e4SLinus Torvalds * kernel data space before using them.. 1151da177e4SLinus Torvalds * 1161da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1171da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1181da177e4SLinus Torvalds */ 119858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds int retval; 1221da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1231da177e4SLinus Torvalds 1241da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1251da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1261da177e4SLinus Torvalds return -EFAULT; 1271da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1281da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1321da177e4SLinus Torvalds if (retval > 0) { 1331da177e4SLinus Torvalds if (retval < len) 1341da177e4SLinus Torvalds return 0; 1351da177e4SLinus Torvalds return -ENAMETOOLONG; 1361da177e4SLinus Torvalds } else if (!retval) 1371da177e4SLinus Torvalds retval = -ENOENT; 1381da177e4SLinus Torvalds return retval; 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411da177e4SLinus Torvalds char * getname(const char __user * filename) 1421da177e4SLinus Torvalds { 1431da177e4SLinus Torvalds char *tmp, *result; 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1461da177e4SLinus Torvalds tmp = __getname(); 1471da177e4SLinus Torvalds if (tmp) { 1481da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1491da177e4SLinus Torvalds 1501da177e4SLinus Torvalds result = tmp; 1511da177e4SLinus Torvalds if (retval < 0) { 1521da177e4SLinus Torvalds __putname(tmp); 1531da177e4SLinus Torvalds result = ERR_PTR(retval); 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds } 1561da177e4SLinus Torvalds audit_getname(result); 1571da177e4SLinus Torvalds return result; 1581da177e4SLinus Torvalds } 1591da177e4SLinus Torvalds 1601da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1611da177e4SLinus Torvalds void putname(const char *name) 1621da177e4SLinus Torvalds { 1635ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1641da177e4SLinus Torvalds audit_putname(name); 1651da177e4SLinus Torvalds else 1661da177e4SLinus Torvalds __putname(name); 1671da177e4SLinus Torvalds } 1681da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1691da177e4SLinus Torvalds #endif 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds 1721da177e4SLinus Torvalds /** 1731da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 1741da177e4SLinus Torvalds * @inode: inode to check access rights for 1751da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 1761da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 1771da177e4SLinus Torvalds * 1781da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 1791da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 1801da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 1811da177e4SLinus Torvalds * are used for other things.. 1821da177e4SLinus Torvalds */ 1831da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 1841da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1851da177e4SLinus Torvalds { 1861da177e4SLinus Torvalds umode_t mode = inode->i_mode; 1871da177e4SLinus Torvalds 188e6305c43SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 189e6305c43SAl Viro 190da9592edSDavid Howells if (current_fsuid() == inode->i_uid) 1911da177e4SLinus Torvalds mode >>= 6; 1921da177e4SLinus Torvalds else { 1931da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1941da177e4SLinus Torvalds int error = check_acl(inode, mask); 1951da177e4SLinus Torvalds if (error == -EACCES) 1961da177e4SLinus Torvalds goto check_capabilities; 1971da177e4SLinus Torvalds else if (error != -EAGAIN) 1981da177e4SLinus Torvalds return error; 1991da177e4SLinus Torvalds } 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 2021da177e4SLinus Torvalds mode >>= 3; 2031da177e4SLinus Torvalds } 2041da177e4SLinus Torvalds 2051da177e4SLinus Torvalds /* 2061da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2071da177e4SLinus Torvalds */ 208e6305c43SAl Viro if ((mask & ~mode) == 0) 2091da177e4SLinus Torvalds return 0; 2101da177e4SLinus Torvalds 2111da177e4SLinus Torvalds check_capabilities: 2121da177e4SLinus Torvalds /* 2131da177e4SLinus Torvalds * Read/write DACs are always overridable. 2141da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2151da177e4SLinus Torvalds */ 216f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 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. */ 252f696a365SMiklos Szeredi if (inode->i_op && inode->i_op->permission) 253b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 254f696a365SMiklos Szeredi else 255e6305c43SAl Viro retval = generic_permission(inode, mask, NULL); 256f696a365SMiklos Szeredi 2571da177e4SLinus Torvalds if (retval) 2581da177e4SLinus Torvalds return retval; 2591da177e4SLinus Torvalds 26008ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 26108ce5f16SSerge E. Hallyn if (retval) 26208ce5f16SSerge E. Hallyn return retval; 26308ce5f16SSerge E. Hallyn 264e6305c43SAl Viro return security_inode_permission(inode, 265f418b006SStephen Smalley mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); 2661da177e4SLinus Torvalds } 2671da177e4SLinus Torvalds 268e4543eddSChristoph Hellwig /** 269e4543eddSChristoph Hellwig * vfs_permission - check for access rights to a given path 270e4543eddSChristoph Hellwig * @nd: lookup result that describes the path 271e4543eddSChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 272e4543eddSChristoph Hellwig * 273e4543eddSChristoph Hellwig * Used to check for read/write/execute permissions on a path. 274e4543eddSChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 275e4543eddSChristoph Hellwig * for filesystem access without changing the "normal" uids which 276e4543eddSChristoph Hellwig * are used for other things. 277e4543eddSChristoph Hellwig */ 278e4543eddSChristoph Hellwig int vfs_permission(struct nameidata *nd, int mask) 279e4543eddSChristoph Hellwig { 280f419a2e3SAl Viro return inode_permission(nd->path.dentry->d_inode, mask); 281e4543eddSChristoph Hellwig } 282e4543eddSChristoph Hellwig 2838c744fb8SChristoph Hellwig /** 2848c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2858c744fb8SChristoph Hellwig * @file: file to check access rights for 2868c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2878c744fb8SChristoph Hellwig * 2888c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 2898c744fb8SChristoph Hellwig * file. 2908c744fb8SChristoph Hellwig * 2918c744fb8SChristoph Hellwig * Note: 2928c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 2938c744fb8SChristoph Hellwig * be done using vfs_permission(). 2948c744fb8SChristoph Hellwig */ 2958c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 2968c744fb8SChristoph Hellwig { 297f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 2988c744fb8SChristoph Hellwig } 2998c744fb8SChristoph Hellwig 3001da177e4SLinus Torvalds /* 3011da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3021da177e4SLinus Torvalds * put_write_access() releases this write permission. 3031da177e4SLinus Torvalds * This is used for regular files. 3041da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3051da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3061da177e4SLinus Torvalds * can have the following values: 3071da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3081da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3091da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3101da177e4SLinus Torvalds * 3111da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3121da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3131da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3141da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3151da177e4SLinus Torvalds * the inode->i_lock spinlock. 3161da177e4SLinus Torvalds */ 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3191da177e4SLinus Torvalds { 3201da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3211da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3221da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3231da177e4SLinus Torvalds return -ETXTBSY; 3241da177e4SLinus Torvalds } 3251da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3261da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3271da177e4SLinus Torvalds 3281da177e4SLinus Torvalds return 0; 3291da177e4SLinus Torvalds } 3301da177e4SLinus Torvalds 3311da177e4SLinus Torvalds int deny_write_access(struct file * file) 3321da177e4SLinus Torvalds { 3330f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3341da177e4SLinus Torvalds 3351da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3361da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3371da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3381da177e4SLinus Torvalds return -ETXTBSY; 3391da177e4SLinus Torvalds } 3401da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3411da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3421da177e4SLinus Torvalds 3431da177e4SLinus Torvalds return 0; 3441da177e4SLinus Torvalds } 3451da177e4SLinus Torvalds 3461d957f9bSJan Blunck /** 3475dd784d0SJan Blunck * path_get - get a reference to a path 3485dd784d0SJan Blunck * @path: path to get the reference to 3495dd784d0SJan Blunck * 3505dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3515dd784d0SJan Blunck */ 3525dd784d0SJan Blunck void path_get(struct path *path) 3535dd784d0SJan Blunck { 3545dd784d0SJan Blunck mntget(path->mnt); 3555dd784d0SJan Blunck dget(path->dentry); 3565dd784d0SJan Blunck } 3575dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3585dd784d0SJan Blunck 3595dd784d0SJan Blunck /** 3601d957f9bSJan Blunck * path_put - put a reference to a path 3611d957f9bSJan Blunck * @path: path to put the reference to 3621d957f9bSJan Blunck * 3631d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3641d957f9bSJan Blunck */ 3651d957f9bSJan Blunck void path_put(struct path *path) 3661da177e4SLinus Torvalds { 3671d957f9bSJan Blunck dput(path->dentry); 3681d957f9bSJan Blunck mntput(path->mnt); 3691da177e4SLinus Torvalds } 3701d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3711da177e4SLinus Torvalds 372834f2a4aSTrond Myklebust /** 373834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 374834f2a4aSTrond Myklebust * @nd: pointer to nameidata 375834f2a4aSTrond Myklebust */ 376834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 377834f2a4aSTrond Myklebust { 3780f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 379834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 380834f2a4aSTrond Myklebust else 381834f2a4aSTrond Myklebust fput(nd->intent.open.file); 382834f2a4aSTrond Myklebust } 383834f2a4aSTrond Myklebust 384bcdc5e01SIan Kent static inline struct dentry * 385bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 386bcdc5e01SIan Kent { 387bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 388bcdc5e01SIan Kent if (unlikely(status <= 0)) { 389bcdc5e01SIan Kent /* 390bcdc5e01SIan Kent * The dentry failed validation. 391bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 392bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 393bcdc5e01SIan Kent * to return a fail status. 394bcdc5e01SIan Kent */ 395bcdc5e01SIan Kent if (!status) { 396bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 397bcdc5e01SIan Kent dput(dentry); 398bcdc5e01SIan Kent dentry = NULL; 399bcdc5e01SIan Kent } 400bcdc5e01SIan Kent } else { 401bcdc5e01SIan Kent dput(dentry); 402bcdc5e01SIan Kent dentry = ERR_PTR(status); 403bcdc5e01SIan Kent } 404bcdc5e01SIan Kent } 405bcdc5e01SIan Kent return dentry; 406bcdc5e01SIan Kent } 407bcdc5e01SIan Kent 4081da177e4SLinus Torvalds /* 4091da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4101da177e4SLinus Torvalds * SMP-safe 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4131da177e4SLinus Torvalds { 4141da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4151da177e4SLinus Torvalds 4161da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4171da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4181da177e4SLinus Torvalds */ 4191da177e4SLinus Torvalds if (!dentry) 4201da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4211da177e4SLinus Torvalds 422bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 423bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 424bcdc5e01SIan Kent 4251da177e4SLinus Torvalds return dentry; 4261da177e4SLinus Torvalds } 4271da177e4SLinus Torvalds 4281da177e4SLinus Torvalds /* 4291da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4301da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4311da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4321da177e4SLinus Torvalds * MAY_EXEC permission. 4331da177e4SLinus Torvalds * 4341da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4351da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4361da177e4SLinus Torvalds * complete permission check. 4371da177e4SLinus Torvalds */ 438672b16b2SAl Viro static int exec_permission_lite(struct inode *inode) 4391da177e4SLinus Torvalds { 4401da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4411da177e4SLinus Torvalds 4421da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4431da177e4SLinus Torvalds return -EAGAIN; 4441da177e4SLinus Torvalds 445da9592edSDavid Howells if (current_fsuid() == inode->i_uid) 4461da177e4SLinus Torvalds mode >>= 6; 4471da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4481da177e4SLinus Torvalds mode >>= 3; 4491da177e4SLinus Torvalds 4501da177e4SLinus Torvalds if (mode & MAY_EXEC) 4511da177e4SLinus Torvalds goto ok; 4521da177e4SLinus Torvalds 4531da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4541da177e4SLinus Torvalds goto ok; 4551da177e4SLinus Torvalds 4561da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4571da177e4SLinus Torvalds goto ok; 4581da177e4SLinus Torvalds 4591da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4601da177e4SLinus Torvalds goto ok; 4611da177e4SLinus Torvalds 4621da177e4SLinus Torvalds return -EACCES; 4631da177e4SLinus Torvalds ok: 464b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4651da177e4SLinus Torvalds } 4661da177e4SLinus Torvalds 4671da177e4SLinus Torvalds /* 4681da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4691da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4701da177e4SLinus Torvalds * 4711da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4721da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4731da177e4SLinus Torvalds * SMP-safe 4741da177e4SLinus Torvalds */ 4751da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4761da177e4SLinus Torvalds { 4771da177e4SLinus Torvalds struct dentry * result; 4781da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4791da177e4SLinus Torvalds 4801b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 4811da177e4SLinus Torvalds /* 4821da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 4831da177e4SLinus Torvalds * while we waited for the directory semaphore.. 4841da177e4SLinus Torvalds * 4851da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 4861da177e4SLinus Torvalds * avoid unnecessary cache lookups. 4871da177e4SLinus Torvalds * 4881da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 4891da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 4901da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 4911da177e4SLinus Torvalds * fast walk). 4921da177e4SLinus Torvalds * 4931da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 4941da177e4SLinus Torvalds */ 4951da177e4SLinus Torvalds result = d_lookup(parent, name); 4961da177e4SLinus Torvalds if (!result) { 497d70b67c8SMiklos Szeredi struct dentry *dentry; 498d70b67c8SMiklos Szeredi 499d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 500d70b67c8SMiklos Szeredi result = ERR_PTR(-ENOENT); 501d70b67c8SMiklos Szeredi if (IS_DEADDIR(dir)) 502d70b67c8SMiklos Szeredi goto out_unlock; 503d70b67c8SMiklos Szeredi 504d70b67c8SMiklos Szeredi dentry = d_alloc(parent, name); 5051da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 5061da177e4SLinus Torvalds if (dentry) { 5071da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5081da177e4SLinus Torvalds if (result) 5091da177e4SLinus Torvalds dput(dentry); 5101da177e4SLinus Torvalds else 5111da177e4SLinus Torvalds result = dentry; 5121da177e4SLinus Torvalds } 513d70b67c8SMiklos Szeredi out_unlock: 5141b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5151da177e4SLinus Torvalds return result; 5161da177e4SLinus Torvalds } 5171da177e4SLinus Torvalds 5181da177e4SLinus Torvalds /* 5191da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5201da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5211da177e4SLinus Torvalds */ 5221b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5231da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 524bcdc5e01SIan Kent result = do_revalidate(result, nd); 525bcdc5e01SIan Kent if (!result) 5261da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5271da177e4SLinus Torvalds } 5281da177e4SLinus Torvalds return result; 5291da177e4SLinus Torvalds } 5301da177e4SLinus Torvalds 5311da177e4SLinus Torvalds /* SMP-safe */ 5327f2da1e7SAl Viro static __always_inline void 5331da177e4SLinus Torvalds walk_init_root(const char *name, struct nameidata *nd) 5341da177e4SLinus Torvalds { 535e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 536e518ddb7SAndreas Mohr 537e518ddb7SAndreas Mohr read_lock(&fs->lock); 5386ac08c39SJan Blunck nd->path = fs->root; 5396ac08c39SJan Blunck path_get(&fs->root); 540e518ddb7SAndreas Mohr read_unlock(&fs->lock); 5411da177e4SLinus Torvalds } 5421da177e4SLinus Torvalds 543a02f76c3SAl Viro /* 544a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 545a02f76c3SAl Viro * file system returns an ESTALE. 546a02f76c3SAl Viro * 547a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 548a02f76c3SAl Viro * instead of relying on the dcache. 549a02f76c3SAl Viro */ 550a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 551a02f76c3SAl Viro { 552a02f76c3SAl Viro struct path save = nd->path; 553a02f76c3SAl Viro int result; 554a02f76c3SAl Viro 555a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 556c8e7f449SJan Blunck path_get(&save); 557a02f76c3SAl Viro 558a02f76c3SAl Viro result = __link_path_walk(name, nd); 559a02f76c3SAl Viro if (result == -ESTALE) { 560a02f76c3SAl Viro /* nd->path had been dropped */ 561a02f76c3SAl Viro nd->path = save; 562c8e7f449SJan Blunck path_get(&nd->path); 563a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 564a02f76c3SAl Viro result = __link_path_walk(name, nd); 565a02f76c3SAl Viro } 566a02f76c3SAl Viro 567a02f76c3SAl Viro path_put(&save); 568a02f76c3SAl Viro 569a02f76c3SAl Viro return result; 570a02f76c3SAl Viro } 571a02f76c3SAl Viro 572f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5731da177e4SLinus Torvalds { 5741da177e4SLinus Torvalds int res = 0; 5751da177e4SLinus Torvalds char *name; 5761da177e4SLinus Torvalds if (IS_ERR(link)) 5771da177e4SLinus Torvalds goto fail; 5781da177e4SLinus Torvalds 5791da177e4SLinus Torvalds if (*link == '/') { 5801d957f9bSJan Blunck path_put(&nd->path); 5817f2da1e7SAl Viro walk_init_root(link, nd); 5821da177e4SLinus Torvalds } 5831da177e4SLinus Torvalds res = link_path_walk(link, nd); 5841da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5851da177e4SLinus Torvalds return res; 5861da177e4SLinus Torvalds /* 5871da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5881da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5891da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5901da177e4SLinus Torvalds */ 5911da177e4SLinus Torvalds name = __getname(); 5921da177e4SLinus Torvalds if (unlikely(!name)) { 5931d957f9bSJan Blunck path_put(&nd->path); 5941da177e4SLinus Torvalds return -ENOMEM; 5951da177e4SLinus Torvalds } 5961da177e4SLinus Torvalds strcpy(name, nd->last.name); 5971da177e4SLinus Torvalds nd->last.name = name; 5981da177e4SLinus Torvalds return 0; 5991da177e4SLinus Torvalds fail: 6001d957f9bSJan Blunck path_put(&nd->path); 6011da177e4SLinus Torvalds return PTR_ERR(link); 6021da177e4SLinus Torvalds } 6031da177e4SLinus Torvalds 6041d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 605051d3812SIan Kent { 606051d3812SIan Kent dput(path->dentry); 6074ac91378SJan Blunck if (path->mnt != nd->path.mnt) 608051d3812SIan Kent mntput(path->mnt); 609051d3812SIan Kent } 610051d3812SIan Kent 611051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 612051d3812SIan Kent { 6134ac91378SJan Blunck dput(nd->path.dentry); 6144ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6154ac91378SJan Blunck mntput(nd->path.mnt); 6164ac91378SJan Blunck nd->path.mnt = path->mnt; 6174ac91378SJan Blunck nd->path.dentry = path->dentry; 618051d3812SIan Kent } 619051d3812SIan Kent 620f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6211da177e4SLinus Torvalds { 6221da177e4SLinus Torvalds int error; 623cc314eefSLinus Torvalds void *cookie; 624cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6251da177e4SLinus Torvalds 626d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6271da177e4SLinus Torvalds nd_set_link(nd, NULL); 628cd4e91d3SAl Viro 6294ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 630051d3812SIan Kent path_to_nameidata(path, nd); 631051d3812SIan Kent dget(dentry); 632051d3812SIan Kent } 633cd4e91d3SAl Viro mntget(path->mnt); 634cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 635cc314eefSLinus Torvalds error = PTR_ERR(cookie); 636cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6371da177e4SLinus Torvalds char *s = nd_get_link(nd); 638cc314eefSLinus Torvalds error = 0; 6391da177e4SLinus Torvalds if (s) 6401da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6411da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 642cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6431da177e4SLinus Torvalds } 64409da5916SJan Blunck path_put(path); 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds return error; 6471da177e4SLinus Torvalds } 6481da177e4SLinus Torvalds 6491da177e4SLinus Torvalds /* 6501da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6511da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6521da177e4SLinus Torvalds * 6531da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6541da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6551da177e4SLinus Torvalds */ 65690ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6571da177e4SLinus Torvalds { 6581da177e4SLinus Torvalds int err = -ELOOP; 6591da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6601da177e4SLinus Torvalds goto loop; 6611da177e4SLinus Torvalds if (current->total_link_count >= 40) 6621da177e4SLinus Torvalds goto loop; 6631da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6641da177e4SLinus Torvalds cond_resched(); 66590ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6661da177e4SLinus Torvalds if (err) 6671da177e4SLinus Torvalds goto loop; 6681da177e4SLinus Torvalds current->link_count++; 6691da177e4SLinus Torvalds current->total_link_count++; 6701da177e4SLinus Torvalds nd->depth++; 671cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6721da177e4SLinus Torvalds current->link_count--; 6731da177e4SLinus Torvalds nd->depth--; 6741da177e4SLinus Torvalds return err; 6751da177e4SLinus Torvalds loop: 6761d957f9bSJan Blunck path_put_conditional(path, nd); 6771d957f9bSJan Blunck path_put(&nd->path); 6781da177e4SLinus Torvalds return err; 6791da177e4SLinus Torvalds } 6801da177e4SLinus Torvalds 6811da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 6821da177e4SLinus Torvalds { 6831da177e4SLinus Torvalds struct vfsmount *parent; 6841da177e4SLinus Torvalds struct dentry *mountpoint; 6851da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6861da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 6871da177e4SLinus Torvalds if (parent == *mnt) { 6881da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6891da177e4SLinus Torvalds return 0; 6901da177e4SLinus Torvalds } 6911da177e4SLinus Torvalds mntget(parent); 6921da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 6931da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6941da177e4SLinus Torvalds dput(*dentry); 6951da177e4SLinus Torvalds *dentry = mountpoint; 6961da177e4SLinus Torvalds mntput(*mnt); 6971da177e4SLinus Torvalds *mnt = parent; 6981da177e4SLinus Torvalds return 1; 6991da177e4SLinus Torvalds } 7001da177e4SLinus Torvalds 7011da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7021da177e4SLinus Torvalds * namespace.c 7031da177e4SLinus Torvalds */ 704463ffb2eSAl Viro static int __follow_mount(struct path *path) 705463ffb2eSAl Viro { 706463ffb2eSAl Viro int res = 0; 707463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 708463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 709463ffb2eSAl Viro if (!mounted) 710463ffb2eSAl Viro break; 711463ffb2eSAl Viro dput(path->dentry); 712463ffb2eSAl Viro if (res) 713463ffb2eSAl Viro mntput(path->mnt); 714463ffb2eSAl Viro path->mnt = mounted; 715463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 716463ffb2eSAl Viro res = 1; 717463ffb2eSAl Viro } 718463ffb2eSAl Viro return res; 719463ffb2eSAl Viro } 720463ffb2eSAl Viro 72158c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7221da177e4SLinus Torvalds { 7231da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7241da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7251da177e4SLinus Torvalds if (!mounted) 7261da177e4SLinus Torvalds break; 72758c465ebSAl Viro dput(*dentry); 7281da177e4SLinus Torvalds mntput(*mnt); 7291da177e4SLinus Torvalds *mnt = mounted; 7301da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7311da177e4SLinus Torvalds } 7321da177e4SLinus Torvalds } 7331da177e4SLinus Torvalds 7341da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7351da177e4SLinus Torvalds * namespace.c 7361da177e4SLinus Torvalds */ 737e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7381da177e4SLinus Torvalds { 7391da177e4SLinus Torvalds struct vfsmount *mounted; 7401da177e4SLinus Torvalds 7411da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7421da177e4SLinus Torvalds if (mounted) { 743e13b210fSAl Viro dput(*dentry); 7441da177e4SLinus Torvalds mntput(*mnt); 7451da177e4SLinus Torvalds *mnt = mounted; 7461da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7471da177e4SLinus Torvalds return 1; 7481da177e4SLinus Torvalds } 7491da177e4SLinus Torvalds return 0; 7501da177e4SLinus Torvalds } 7511da177e4SLinus Torvalds 752f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7531da177e4SLinus Torvalds { 754e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 755e518ddb7SAndreas Mohr 7561da177e4SLinus Torvalds while(1) { 7571da177e4SLinus Torvalds struct vfsmount *parent; 7584ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7591da177e4SLinus Torvalds 760e518ddb7SAndreas Mohr read_lock(&fs->lock); 7616ac08c39SJan Blunck if (nd->path.dentry == fs->root.dentry && 7626ac08c39SJan Blunck nd->path.mnt == fs->root.mnt) { 763e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7641da177e4SLinus Torvalds break; 7651da177e4SLinus Torvalds } 766e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7671da177e4SLinus Torvalds spin_lock(&dcache_lock); 7684ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7694ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7701da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7711da177e4SLinus Torvalds dput(old); 7721da177e4SLinus Torvalds break; 7731da177e4SLinus Torvalds } 7741da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7751da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7764ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7774ac91378SJan Blunck if (parent == nd->path.mnt) { 7781da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7791da177e4SLinus Torvalds break; 7801da177e4SLinus Torvalds } 7811da177e4SLinus Torvalds mntget(parent); 7824ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7831da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7841da177e4SLinus Torvalds dput(old); 7854ac91378SJan Blunck mntput(nd->path.mnt); 7864ac91378SJan Blunck nd->path.mnt = parent; 7871da177e4SLinus Torvalds } 7884ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 7891da177e4SLinus Torvalds } 7901da177e4SLinus Torvalds 7911da177e4SLinus Torvalds /* 7921da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7931da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7941da177e4SLinus Torvalds * It _is_ time-critical. 7951da177e4SLinus Torvalds */ 7961da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7971da177e4SLinus Torvalds struct path *path) 7981da177e4SLinus Torvalds { 7994ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 8004ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 8011da177e4SLinus Torvalds 8021da177e4SLinus Torvalds if (!dentry) 8031da177e4SLinus Torvalds goto need_lookup; 8041da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 8051da177e4SLinus Torvalds goto need_revalidate; 8061da177e4SLinus Torvalds done: 8071da177e4SLinus Torvalds path->mnt = mnt; 8081da177e4SLinus Torvalds path->dentry = dentry; 809634ee701SAl Viro __follow_mount(path); 8101da177e4SLinus Torvalds return 0; 8111da177e4SLinus Torvalds 8121da177e4SLinus Torvalds need_lookup: 8134ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8141da177e4SLinus Torvalds if (IS_ERR(dentry)) 8151da177e4SLinus Torvalds goto fail; 8161da177e4SLinus Torvalds goto done; 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds need_revalidate: 819bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 820bcdc5e01SIan Kent if (!dentry) 8211da177e4SLinus Torvalds goto need_lookup; 822bcdc5e01SIan Kent if (IS_ERR(dentry)) 823bcdc5e01SIan Kent goto fail; 824bcdc5e01SIan Kent goto done; 8251da177e4SLinus Torvalds 8261da177e4SLinus Torvalds fail: 8271da177e4SLinus Torvalds return PTR_ERR(dentry); 8281da177e4SLinus Torvalds } 8291da177e4SLinus Torvalds 8301da177e4SLinus Torvalds /* 8311da177e4SLinus Torvalds * Name resolution. 832ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 833ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8341da177e4SLinus Torvalds * 835ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 836ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8371da177e4SLinus Torvalds */ 838fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8391da177e4SLinus Torvalds { 8401da177e4SLinus Torvalds struct path next; 8411da177e4SLinus Torvalds struct inode *inode; 8421da177e4SLinus Torvalds int err; 8431da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8441da177e4SLinus Torvalds 8451da177e4SLinus Torvalds while (*name=='/') 8461da177e4SLinus Torvalds name++; 8471da177e4SLinus Torvalds if (!*name) 8481da177e4SLinus Torvalds goto return_reval; 8491da177e4SLinus Torvalds 8504ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8511da177e4SLinus Torvalds if (nd->depth) 852f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8531da177e4SLinus Torvalds 8541da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8551da177e4SLinus Torvalds for(;;) { 8561da177e4SLinus Torvalds unsigned long hash; 8571da177e4SLinus Torvalds struct qstr this; 8581da177e4SLinus Torvalds unsigned int c; 8591da177e4SLinus Torvalds 860cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 861672b16b2SAl Viro err = exec_permission_lite(inode); 862e4543eddSChristoph Hellwig if (err == -EAGAIN) 863e4543eddSChristoph Hellwig err = vfs_permission(nd, MAY_EXEC); 8646146f0d5SMimi Zohar if (!err) 8656146f0d5SMimi Zohar err = ima_path_check(&nd->path, MAY_EXEC); 8661da177e4SLinus Torvalds if (err) 8671da177e4SLinus Torvalds break; 8681da177e4SLinus Torvalds 8691da177e4SLinus Torvalds this.name = name; 8701da177e4SLinus Torvalds c = *(const unsigned char *)name; 8711da177e4SLinus Torvalds 8721da177e4SLinus Torvalds hash = init_name_hash(); 8731da177e4SLinus Torvalds do { 8741da177e4SLinus Torvalds name++; 8751da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8761da177e4SLinus Torvalds c = *(const unsigned char *)name; 8771da177e4SLinus Torvalds } while (c && (c != '/')); 8781da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8791da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8801da177e4SLinus Torvalds 8811da177e4SLinus Torvalds /* remove trailing slashes? */ 8821da177e4SLinus Torvalds if (!c) 8831da177e4SLinus Torvalds goto last_component; 8841da177e4SLinus Torvalds while (*++name == '/'); 8851da177e4SLinus Torvalds if (!*name) 8861da177e4SLinus Torvalds goto last_with_slashes; 8871da177e4SLinus Torvalds 8881da177e4SLinus Torvalds /* 8891da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8901da177e4SLinus Torvalds * to be able to know about the current root directory and 8911da177e4SLinus Torvalds * parent relationships. 8921da177e4SLinus Torvalds */ 8931da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8941da177e4SLinus Torvalds default: 8951da177e4SLinus Torvalds break; 8961da177e4SLinus Torvalds case 2: 8971da177e4SLinus Torvalds if (this.name[1] != '.') 8981da177e4SLinus Torvalds break; 89958c465ebSAl Viro follow_dotdot(nd); 9004ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9011da177e4SLinus Torvalds /* fallthrough */ 9021da177e4SLinus Torvalds case 1: 9031da177e4SLinus Torvalds continue; 9041da177e4SLinus Torvalds } 9051da177e4SLinus Torvalds /* 9061da177e4SLinus Torvalds * See if the low-level filesystem might want 9071da177e4SLinus Torvalds * to use its own hash.. 9081da177e4SLinus Torvalds */ 9094ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9104ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9114ac91378SJan Blunck &this); 9121da177e4SLinus Torvalds if (err < 0) 9131da177e4SLinus Torvalds break; 9141da177e4SLinus Torvalds } 9151da177e4SLinus Torvalds /* This does the actual lookups.. */ 9161da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9171da177e4SLinus Torvalds if (err) 9181da177e4SLinus Torvalds break; 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds err = -ENOENT; 9211da177e4SLinus Torvalds inode = next.dentry->d_inode; 9221da177e4SLinus Torvalds if (!inode) 9231da177e4SLinus Torvalds goto out_dput; 9241da177e4SLinus Torvalds err = -ENOTDIR; 9251da177e4SLinus Torvalds if (!inode->i_op) 9261da177e4SLinus Torvalds goto out_dput; 9271da177e4SLinus Torvalds 9281da177e4SLinus Torvalds if (inode->i_op->follow_link) { 92990ebe565SAl Viro err = do_follow_link(&next, nd); 9301da177e4SLinus Torvalds if (err) 9311da177e4SLinus Torvalds goto return_err; 9321da177e4SLinus Torvalds err = -ENOENT; 9334ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9341da177e4SLinus Torvalds if (!inode) 9351da177e4SLinus Torvalds break; 9361da177e4SLinus Torvalds err = -ENOTDIR; 9371da177e4SLinus Torvalds if (!inode->i_op) 9381da177e4SLinus Torvalds break; 93909dd17d3SMiklos Szeredi } else 94009dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9411da177e4SLinus Torvalds err = -ENOTDIR; 9421da177e4SLinus Torvalds if (!inode->i_op->lookup) 9431da177e4SLinus Torvalds break; 9441da177e4SLinus Torvalds continue; 9451da177e4SLinus Torvalds /* here ends the main loop */ 9461da177e4SLinus Torvalds 9471da177e4SLinus Torvalds last_with_slashes: 9481da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9491da177e4SLinus Torvalds last_component: 950f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 951f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9521da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9531da177e4SLinus Torvalds goto lookup_parent; 9541da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9551da177e4SLinus Torvalds default: 9561da177e4SLinus Torvalds break; 9571da177e4SLinus Torvalds case 2: 9581da177e4SLinus Torvalds if (this.name[1] != '.') 9591da177e4SLinus Torvalds break; 96058c465ebSAl Viro follow_dotdot(nd); 9614ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9621da177e4SLinus Torvalds /* fallthrough */ 9631da177e4SLinus Torvalds case 1: 9641da177e4SLinus Torvalds goto return_reval; 9651da177e4SLinus Torvalds } 9664ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9674ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9684ac91378SJan Blunck &this); 9691da177e4SLinus Torvalds if (err < 0) 9701da177e4SLinus Torvalds break; 9711da177e4SLinus Torvalds } 9721da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9731da177e4SLinus Torvalds if (err) 9741da177e4SLinus Torvalds break; 9751da177e4SLinus Torvalds inode = next.dentry->d_inode; 9761da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 9771da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 97890ebe565SAl Viro err = do_follow_link(&next, nd); 9791da177e4SLinus Torvalds if (err) 9801da177e4SLinus Torvalds goto return_err; 9814ac91378SJan Blunck inode = nd->path.dentry->d_inode; 98209dd17d3SMiklos Szeredi } else 98309dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9841da177e4SLinus Torvalds err = -ENOENT; 9851da177e4SLinus Torvalds if (!inode) 9861da177e4SLinus Torvalds break; 9871da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9881da177e4SLinus Torvalds err = -ENOTDIR; 9891da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 9901da177e4SLinus Torvalds break; 9911da177e4SLinus Torvalds } 9921da177e4SLinus Torvalds goto return_base; 9931da177e4SLinus Torvalds lookup_parent: 9941da177e4SLinus Torvalds nd->last = this; 9951da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9961da177e4SLinus Torvalds if (this.name[0] != '.') 9971da177e4SLinus Torvalds goto return_base; 9981da177e4SLinus Torvalds if (this.len == 1) 9991da177e4SLinus Torvalds nd->last_type = LAST_DOT; 10001da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 10011da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 10021da177e4SLinus Torvalds else 10031da177e4SLinus Torvalds goto return_base; 10041da177e4SLinus Torvalds return_reval: 10051da177e4SLinus Torvalds /* 10061da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 10071da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 10081da177e4SLinus Torvalds */ 10094ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 10104ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 10111da177e4SLinus Torvalds err = -ESTALE; 10121da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10134ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10144ac91378SJan Blunck nd->path.dentry, nd)) 10151da177e4SLinus Torvalds break; 10161da177e4SLinus Torvalds } 10171da177e4SLinus Torvalds return_base: 10181da177e4SLinus Torvalds return 0; 10191da177e4SLinus Torvalds out_dput: 10201d957f9bSJan Blunck path_put_conditional(&next, nd); 10211da177e4SLinus Torvalds break; 10221da177e4SLinus Torvalds } 10231d957f9bSJan Blunck path_put(&nd->path); 10241da177e4SLinus Torvalds return_err: 10251da177e4SLinus Torvalds return err; 10261da177e4SLinus Torvalds } 10271da177e4SLinus Torvalds 1028fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10291da177e4SLinus Torvalds { 10301da177e4SLinus Torvalds current->total_link_count = 0; 10311da177e4SLinus Torvalds return link_path_walk(name, nd); 10321da177e4SLinus Torvalds } 10331da177e4SLinus Torvalds 1034ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1035fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 10365590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 10371da177e4SLinus Torvalds { 1038ea3834d9SPrasanna Meda int retval = 0; 1039170aa3d0SUlrich Drepper int fput_needed; 1040170aa3d0SUlrich Drepper struct file *file; 1041e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 10421da177e4SLinus Torvalds 10431da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10441da177e4SLinus Torvalds nd->flags = flags; 10451da177e4SLinus Torvalds nd->depth = 0; 10461da177e4SLinus Torvalds 10471da177e4SLinus Torvalds if (*name=='/') { 1048e518ddb7SAndreas Mohr read_lock(&fs->lock); 10496ac08c39SJan Blunck nd->path = fs->root; 10506ac08c39SJan Blunck path_get(&fs->root); 1051e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10525590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1053e518ddb7SAndreas Mohr read_lock(&fs->lock); 10546ac08c39SJan Blunck nd->path = fs->pwd; 10556ac08c39SJan Blunck path_get(&fs->pwd); 1056e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10575590ff0dSUlrich Drepper } else { 10585590ff0dSUlrich Drepper struct dentry *dentry; 10595590ff0dSUlrich Drepper 10605590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10615590ff0dSUlrich Drepper retval = -EBADF; 1062170aa3d0SUlrich Drepper if (!file) 10636d09bb62STrond Myklebust goto out_fail; 10645590ff0dSUlrich Drepper 10650f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10665590ff0dSUlrich Drepper 10675590ff0dSUlrich Drepper retval = -ENOTDIR; 1068170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10696d09bb62STrond Myklebust goto fput_fail; 10705590ff0dSUlrich Drepper 10715590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1072170aa3d0SUlrich Drepper if (retval) 10736d09bb62STrond Myklebust goto fput_fail; 10745590ff0dSUlrich Drepper 10755dd784d0SJan Blunck nd->path = file->f_path; 10765dd784d0SJan Blunck path_get(&file->f_path); 10775590ff0dSUlrich Drepper 10785590ff0dSUlrich Drepper fput_light(file, fput_needed); 10791da177e4SLinus Torvalds } 10802dfdd266SJosef 'Jeff' Sipek 10812dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10824ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10834ac91378SJan Blunck nd->path.dentry->d_inode)) 10844ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10856d09bb62STrond Myklebust out_fail: 1086170aa3d0SUlrich Drepper return retval; 1087170aa3d0SUlrich Drepper 10886d09bb62STrond Myklebust fput_fail: 1089170aa3d0SUlrich Drepper fput_light(file, fput_needed); 10906d09bb62STrond Myklebust goto out_fail; 10911da177e4SLinus Torvalds } 10921da177e4SLinus Torvalds 1093fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 10945590ff0dSUlrich Drepper struct nameidata *nd) 10955590ff0dSUlrich Drepper { 10965590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 10975590ff0dSUlrich Drepper } 10985590ff0dSUlrich Drepper 1099d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1100d1811465SAl Viro { 1101d1811465SAl Viro struct nameidata nd; 1102d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1103d1811465SAl Viro if (!res) 1104d1811465SAl Viro *path = nd.path; 1105d1811465SAl Viro return res; 1106d1811465SAl Viro } 1107d1811465SAl Viro 110816f18200SJosef 'Jeff' Sipek /** 110916f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 111016f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 111116f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 111216f18200SJosef 'Jeff' Sipek * @name: pointer to file name 111316f18200SJosef 'Jeff' Sipek * @flags: lookup flags 111416f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 111516f18200SJosef 'Jeff' Sipek */ 111616f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 111716f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 111816f18200SJosef 'Jeff' Sipek struct nameidata *nd) 111916f18200SJosef 'Jeff' Sipek { 112016f18200SJosef 'Jeff' Sipek int retval; 112116f18200SJosef 'Jeff' Sipek 112216f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 112316f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 112416f18200SJosef 'Jeff' Sipek nd->flags = flags; 112516f18200SJosef 'Jeff' Sipek nd->depth = 0; 112616f18200SJosef 'Jeff' Sipek 1127c8e7f449SJan Blunck nd->path.dentry = dentry; 1128c8e7f449SJan Blunck nd->path.mnt = mnt; 1129c8e7f449SJan Blunck path_get(&nd->path); 113016f18200SJosef 'Jeff' Sipek 113116f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11324ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11334ac91378SJan Blunck nd->path.dentry->d_inode)) 11344ac91378SJan Blunck audit_inode(name, nd->path.dentry); 113516f18200SJosef 'Jeff' Sipek 113616f18200SJosef 'Jeff' Sipek return retval; 113716f18200SJosef 'Jeff' Sipek 113816f18200SJosef 'Jeff' Sipek } 113916f18200SJosef 'Jeff' Sipek 1140834f2a4aSTrond Myklebust /** 1141834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 11427045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1143834f2a4aSTrond Myklebust * @name: pointer to file name 1144834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1145834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1146834f2a4aSTrond Myklebust * @open_flags: open intent flags 1147834f2a4aSTrond Myklebust */ 11485590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1149834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1150834f2a4aSTrond Myklebust { 11518737f3a1SAl Viro struct file *filp = get_empty_filp(); 11528737f3a1SAl Viro int err; 1153834f2a4aSTrond Myklebust 11548737f3a1SAl Viro if (filp == NULL) 11558737f3a1SAl Viro return -ENFILE; 11568737f3a1SAl Viro nd->intent.open.file = filp; 11578737f3a1SAl Viro nd->intent.open.flags = open_flags; 11588737f3a1SAl Viro nd->intent.open.create_mode = 0; 11598737f3a1SAl Viro err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 11608737f3a1SAl Viro if (IS_ERR(nd->intent.open.file)) { 11618737f3a1SAl Viro if (err == 0) { 11628737f3a1SAl Viro err = PTR_ERR(nd->intent.open.file); 11638737f3a1SAl Viro path_put(&nd->path); 11648737f3a1SAl Viro } 11658737f3a1SAl Viro } else if (err != 0) 11668737f3a1SAl Viro release_open_intent(nd); 11678737f3a1SAl Viro return err; 1168834f2a4aSTrond Myklebust } 1169834f2a4aSTrond Myklebust 1170eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1171eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 11721da177e4SLinus Torvalds { 11731da177e4SLinus Torvalds struct dentry *dentry; 11741da177e4SLinus Torvalds struct inode *inode; 11751da177e4SLinus Torvalds int err; 11761da177e4SLinus Torvalds 11771da177e4SLinus Torvalds inode = base->d_inode; 11781da177e4SLinus Torvalds 11791da177e4SLinus Torvalds /* 11801da177e4SLinus Torvalds * See if the low-level filesystem might want 11811da177e4SLinus Torvalds * to use its own hash.. 11821da177e4SLinus Torvalds */ 11831da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 11841da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 11851da177e4SLinus Torvalds dentry = ERR_PTR(err); 11861da177e4SLinus Torvalds if (err < 0) 11871da177e4SLinus Torvalds goto out; 11881da177e4SLinus Torvalds } 11891da177e4SLinus Torvalds 11901da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 11911da177e4SLinus Torvalds if (!dentry) { 1192d70b67c8SMiklos Szeredi struct dentry *new; 1193d70b67c8SMiklos Szeredi 1194d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1195d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1196d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1197d70b67c8SMiklos Szeredi goto out; 1198d70b67c8SMiklos Szeredi 1199d70b67c8SMiklos Szeredi new = d_alloc(base, name); 12001da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 12011da177e4SLinus Torvalds if (!new) 12021da177e4SLinus Torvalds goto out; 12031da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 12041da177e4SLinus Torvalds if (!dentry) 12051da177e4SLinus Torvalds dentry = new; 12061da177e4SLinus Torvalds else 12071da177e4SLinus Torvalds dput(new); 12081da177e4SLinus Torvalds } 12091da177e4SLinus Torvalds out: 12101da177e4SLinus Torvalds return dentry; 12111da177e4SLinus Torvalds } 12121da177e4SLinus Torvalds 1213057f6c01SJames Morris /* 1214057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1215057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1216057f6c01SJames Morris * SMP-safe. 1217057f6c01SJames Morris */ 1218a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 12191da177e4SLinus Torvalds { 1220eead1911SChristoph Hellwig int err; 1221eead1911SChristoph Hellwig 1222f419a2e3SAl Viro err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC); 1223eead1911SChristoph Hellwig if (err) 1224eead1911SChristoph Hellwig return ERR_PTR(err); 12254ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 12261da177e4SLinus Torvalds } 12271da177e4SLinus Torvalds 1228eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1229eead1911SChristoph Hellwig struct dentry *base, int len) 12301da177e4SLinus Torvalds { 12311da177e4SLinus Torvalds unsigned long hash; 12321da177e4SLinus Torvalds unsigned int c; 12331da177e4SLinus Torvalds 1234057f6c01SJames Morris this->name = name; 1235057f6c01SJames Morris this->len = len; 12361da177e4SLinus Torvalds if (!len) 1237057f6c01SJames Morris return -EACCES; 12381da177e4SLinus Torvalds 12391da177e4SLinus Torvalds hash = init_name_hash(); 12401da177e4SLinus Torvalds while (len--) { 12411da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12421da177e4SLinus Torvalds if (c == '/' || c == '\0') 1243057f6c01SJames Morris return -EACCES; 12441da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12451da177e4SLinus Torvalds } 1246057f6c01SJames Morris this->hash = end_name_hash(hash); 1247057f6c01SJames Morris return 0; 1248057f6c01SJames Morris } 12491da177e4SLinus Torvalds 1250eead1911SChristoph Hellwig /** 1251a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1252eead1911SChristoph Hellwig * @name: pathname component to lookup 1253eead1911SChristoph Hellwig * @base: base directory to lookup from 1254eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1255eead1911SChristoph Hellwig * 1256a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1257a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1258eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1259eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1260eead1911SChristoph Hellwig */ 1261057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1262057f6c01SJames Morris { 1263057f6c01SJames Morris int err; 1264057f6c01SJames Morris struct qstr this; 1265057f6c01SJames Morris 1266057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1267057f6c01SJames Morris if (err) 1268057f6c01SJames Morris return ERR_PTR(err); 1269eead1911SChristoph Hellwig 1270f419a2e3SAl Viro err = inode_permission(base->d_inode, MAY_EXEC); 1271eead1911SChristoph Hellwig if (err) 1272eead1911SChristoph Hellwig return ERR_PTR(err); 127349705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1274057f6c01SJames Morris } 1275057f6c01SJames Morris 1276eead1911SChristoph Hellwig /** 1277eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1278eead1911SChristoph Hellwig * @name: pathname component to lookup 1279eead1911SChristoph Hellwig * @base: base directory to lookup from 1280eead1911SChristoph Hellwig * 1281eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1282eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1283eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1284eead1911SChristoph Hellwig * 1285eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1286eead1911SChristoph Hellwig */ 1287eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1288057f6c01SJames Morris { 1289057f6c01SJames Morris int err; 1290057f6c01SJames Morris struct qstr this; 1291057f6c01SJames Morris 1292eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1293057f6c01SJames Morris if (err) 1294057f6c01SJames Morris return ERR_PTR(err); 1295eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 12961da177e4SLinus Torvalds } 12971da177e4SLinus Torvalds 12982d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 12992d8f3038SAl Viro struct path *path) 13001da177e4SLinus Torvalds { 13012d8f3038SAl Viro struct nameidata nd; 13021da177e4SLinus Torvalds char *tmp = getname(name); 13031da177e4SLinus Torvalds int err = PTR_ERR(tmp); 13041da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 13052d8f3038SAl Viro 13062d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 13072d8f3038SAl Viro 13082d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 13091da177e4SLinus Torvalds putname(tmp); 13102d8f3038SAl Viro if (!err) 13112d8f3038SAl Viro *path = nd.path; 13121da177e4SLinus Torvalds } 13131da177e4SLinus Torvalds return err; 13141da177e4SLinus Torvalds } 13151da177e4SLinus Torvalds 13162ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 13172ad94ae6SAl Viro struct nameidata *nd, char **name) 13182ad94ae6SAl Viro { 13192ad94ae6SAl Viro char *s = getname(path); 13202ad94ae6SAl Viro int error; 13212ad94ae6SAl Viro 13222ad94ae6SAl Viro if (IS_ERR(s)) 13232ad94ae6SAl Viro return PTR_ERR(s); 13242ad94ae6SAl Viro 13252ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 13262ad94ae6SAl Viro if (error) 13272ad94ae6SAl Viro putname(s); 13282ad94ae6SAl Viro else 13292ad94ae6SAl Viro *name = s; 13302ad94ae6SAl Viro 13312ad94ae6SAl Viro return error; 13322ad94ae6SAl Viro } 13332ad94ae6SAl Viro 13341da177e4SLinus Torvalds /* 13351da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 13361da177e4SLinus Torvalds * minimal. 13371da177e4SLinus Torvalds */ 13381da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 13391da177e4SLinus Torvalds { 1340da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1341da9592edSDavid Howells 13421da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 13431da177e4SLinus Torvalds return 0; 1344da9592edSDavid Howells if (inode->i_uid == fsuid) 13451da177e4SLinus Torvalds return 0; 1346da9592edSDavid Howells if (dir->i_uid == fsuid) 13471da177e4SLinus Torvalds return 0; 13481da177e4SLinus Torvalds return !capable(CAP_FOWNER); 13491da177e4SLinus Torvalds } 13501da177e4SLinus Torvalds 13511da177e4SLinus Torvalds /* 13521da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 13531da177e4SLinus Torvalds * whether the type of victim is right. 13541da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 13551da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 13561da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 13571da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13581da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13591da177e4SLinus Torvalds * a. be owner of dir, or 13601da177e4SLinus Torvalds * b. be owner of victim, or 13611da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13621da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 13631da177e4SLinus Torvalds * links pointing to it. 13641da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 13651da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 13661da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 13671da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 13681da177e4SLinus Torvalds * nfs_async_unlink(). 13691da177e4SLinus Torvalds */ 1370858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 13711da177e4SLinus Torvalds { 13721da177e4SLinus Torvalds int error; 13731da177e4SLinus Torvalds 13741da177e4SLinus Torvalds if (!victim->d_inode) 13751da177e4SLinus Torvalds return -ENOENT; 13761da177e4SLinus Torvalds 13771da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 13785a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 13791da177e4SLinus Torvalds 1380f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 13811da177e4SLinus Torvalds if (error) 13821da177e4SLinus Torvalds return error; 13831da177e4SLinus Torvalds if (IS_APPEND(dir)) 13841da177e4SLinus Torvalds return -EPERM; 13851da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1386f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 13871da177e4SLinus Torvalds return -EPERM; 13881da177e4SLinus Torvalds if (isdir) { 13891da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 13901da177e4SLinus Torvalds return -ENOTDIR; 13911da177e4SLinus Torvalds if (IS_ROOT(victim)) 13921da177e4SLinus Torvalds return -EBUSY; 13931da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 13941da177e4SLinus Torvalds return -EISDIR; 13951da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13961da177e4SLinus Torvalds return -ENOENT; 13971da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 13981da177e4SLinus Torvalds return -EBUSY; 13991da177e4SLinus Torvalds return 0; 14001da177e4SLinus Torvalds } 14011da177e4SLinus Torvalds 14021da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 14031da177e4SLinus Torvalds * dir. 14041da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 14051da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 14061da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 14071da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 14081da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 14091da177e4SLinus Torvalds */ 1410a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 14111da177e4SLinus Torvalds { 14121da177e4SLinus Torvalds if (child->d_inode) 14131da177e4SLinus Torvalds return -EEXIST; 14141da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14151da177e4SLinus Torvalds return -ENOENT; 1416f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 14171da177e4SLinus Torvalds } 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds /* 14201da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 14211da177e4SLinus Torvalds */ 14221da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 14231da177e4SLinus Torvalds { 14241da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 14251da177e4SLinus Torvalds 14261da177e4SLinus Torvalds if (f & O_NOFOLLOW) 14271da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds if (f & O_DIRECTORY) 14301da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 14311da177e4SLinus Torvalds 14321da177e4SLinus Torvalds return retval; 14331da177e4SLinus Torvalds } 14341da177e4SLinus Torvalds 14351da177e4SLinus Torvalds /* 14361da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 14371da177e4SLinus Torvalds */ 14381da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 14391da177e4SLinus Torvalds { 14401da177e4SLinus Torvalds struct dentry *p; 14411da177e4SLinus Torvalds 14421da177e4SLinus Torvalds if (p1 == p2) { 1443f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 14441da177e4SLinus Torvalds return NULL; 14451da177e4SLinus Torvalds } 14461da177e4SLinus Torvalds 1447a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14481da177e4SLinus Torvalds 1449e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1450e2761a11SOGAWA Hirofumi if (p) { 1451f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1452f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 14531da177e4SLinus Torvalds return p; 14541da177e4SLinus Torvalds } 14551da177e4SLinus Torvalds 1456e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1457e2761a11SOGAWA Hirofumi if (p) { 1458f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1459f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14601da177e4SLinus Torvalds return p; 14611da177e4SLinus Torvalds } 14621da177e4SLinus Torvalds 1463f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1464f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14651da177e4SLinus Torvalds return NULL; 14661da177e4SLinus Torvalds } 14671da177e4SLinus Torvalds 14681da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 14691da177e4SLinus Torvalds { 14701b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 14711da177e4SLinus Torvalds if (p1 != p2) { 14721b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1473a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14741da177e4SLinus Torvalds } 14751da177e4SLinus Torvalds } 14761da177e4SLinus Torvalds 14771da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 14781da177e4SLinus Torvalds struct nameidata *nd) 14791da177e4SLinus Torvalds { 1480a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 14811da177e4SLinus Torvalds 14821da177e4SLinus Torvalds if (error) 14831da177e4SLinus Torvalds return error; 14841da177e4SLinus Torvalds 14851da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 14861da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 14871da177e4SLinus Torvalds mode &= S_IALLUGO; 14881da177e4SLinus Torvalds mode |= S_IFREG; 14891da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 14901da177e4SLinus Torvalds if (error) 14911da177e4SLinus Torvalds return error; 14921da177e4SLinus Torvalds DQUOT_INIT(dir); 14931da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1494a74574aaSStephen Smalley if (!error) 1495f38aa942SAmy Griffis fsnotify_create(dir, dentry); 14961da177e4SLinus Torvalds return error; 14971da177e4SLinus Torvalds } 14981da177e4SLinus Torvalds 14991da177e4SLinus Torvalds int may_open(struct nameidata *nd, int acc_mode, int flag) 15001da177e4SLinus Torvalds { 15014ac91378SJan Blunck struct dentry *dentry = nd->path.dentry; 15021da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 15031da177e4SLinus Torvalds int error; 15041da177e4SLinus Torvalds 15051da177e4SLinus Torvalds if (!inode) 15061da177e4SLinus Torvalds return -ENOENT; 15071da177e4SLinus Torvalds 15081da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 15091da177e4SLinus Torvalds return -ELOOP; 15101da177e4SLinus Torvalds 1511974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 15121da177e4SLinus Torvalds return -EISDIR; 15131da177e4SLinus Torvalds 15141da177e4SLinus Torvalds /* 15151da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 15161da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 15171da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 15181da177e4SLinus Torvalds */ 15191da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 15201da177e4SLinus Torvalds flag &= ~O_TRUNC; 15211da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 15224ac91378SJan Blunck if (nd->path.mnt->mnt_flags & MNT_NODEV) 15231da177e4SLinus Torvalds return -EACCES; 15241da177e4SLinus Torvalds 15251da177e4SLinus Torvalds flag &= ~O_TRUNC; 15264a3fd211SDave Hansen } 1527b41572e9SDave Hansen 1528b41572e9SDave Hansen error = vfs_permission(nd, acc_mode); 1529b41572e9SDave Hansen if (error) 1530b41572e9SDave Hansen return error; 15316146f0d5SMimi Zohar 15326146f0d5SMimi Zohar error = ima_path_check(&nd->path, 15336146f0d5SMimi Zohar acc_mode & (MAY_READ | MAY_WRITE | MAY_EXEC)); 15346146f0d5SMimi Zohar if (error) 15356146f0d5SMimi Zohar return error; 15361da177e4SLinus Torvalds /* 15371da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 15381da177e4SLinus Torvalds */ 15391da177e4SLinus Torvalds if (IS_APPEND(inode)) { 15401da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 15411da177e4SLinus Torvalds return -EPERM; 15421da177e4SLinus Torvalds if (flag & O_TRUNC) 15431da177e4SLinus Torvalds return -EPERM; 15441da177e4SLinus Torvalds } 15451da177e4SLinus Torvalds 15461da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15471da177e4SLinus Torvalds if (flag & O_NOATIME) 15483bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 15491da177e4SLinus Torvalds return -EPERM; 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds /* 15521da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15531da177e4SLinus Torvalds */ 15541da177e4SLinus Torvalds error = break_lease(inode, flag); 15551da177e4SLinus Torvalds if (error) 15561da177e4SLinus Torvalds return error; 15571da177e4SLinus Torvalds 15581da177e4SLinus Torvalds if (flag & O_TRUNC) { 15591da177e4SLinus Torvalds error = get_write_access(inode); 15601da177e4SLinus Torvalds if (error) 15611da177e4SLinus Torvalds return error; 15621da177e4SLinus Torvalds 15631da177e4SLinus Torvalds /* 15641da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 15651da177e4SLinus Torvalds */ 15661da177e4SLinus Torvalds error = locks_verify_locked(inode); 15671da177e4SLinus Torvalds if (!error) { 15681da177e4SLinus Torvalds DQUOT_INIT(inode); 15691da177e4SLinus Torvalds 1570d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1571d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1572d139d7ffSMiklos Szeredi NULL); 15731da177e4SLinus Torvalds } 15741da177e4SLinus Torvalds put_write_access(inode); 15751da177e4SLinus Torvalds if (error) 15761da177e4SLinus Torvalds return error; 15771da177e4SLinus Torvalds } else 15781da177e4SLinus Torvalds if (flag & FMODE_WRITE) 15791da177e4SLinus Torvalds DQUOT_INIT(inode); 15801da177e4SLinus Torvalds 15811da177e4SLinus Torvalds return 0; 15821da177e4SLinus Torvalds } 15831da177e4SLinus Torvalds 1584d57999e1SDave Hansen /* 1585d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1586d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1587d57999e1SDave Hansen * what get passed to sys_open(). 1588d57999e1SDave Hansen */ 1589d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1590aab520e2SDave Hansen int flag, int mode) 1591aab520e2SDave Hansen { 1592aab520e2SDave Hansen int error; 15934ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1594aab520e2SDave Hansen 1595aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1596aab520e2SDave Hansen mode &= ~current->fs->umask; 1597aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1598aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 15994ac91378SJan Blunck dput(nd->path.dentry); 16004ac91378SJan Blunck nd->path.dentry = path->dentry; 1601aab520e2SDave Hansen if (error) 1602aab520e2SDave Hansen return error; 1603aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 1604aab520e2SDave Hansen return may_open(nd, 0, flag & ~O_TRUNC); 1605aab520e2SDave Hansen } 1606aab520e2SDave Hansen 16071da177e4SLinus Torvalds /* 1608d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1609d57999e1SDave Hansen * 00 - read-only 1610d57999e1SDave Hansen * 01 - write-only 1611d57999e1SDave Hansen * 10 - read-write 1612d57999e1SDave Hansen * 11 - special 1613d57999e1SDave Hansen * it is changed into 1614d57999e1SDave Hansen * 00 - no permissions needed 1615d57999e1SDave Hansen * 01 - read-permission 1616d57999e1SDave Hansen * 10 - write-permission 1617d57999e1SDave Hansen * 11 - read-write 1618d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1619d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1620d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1621d57999e1SDave Hansen * later). 1622d57999e1SDave Hansen * 1623d57999e1SDave Hansen */ 1624d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1625d57999e1SDave Hansen { 1626d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1627d57999e1SDave Hansen flag++; 1628d57999e1SDave Hansen return flag; 1629d57999e1SDave Hansen } 1630d57999e1SDave Hansen 16314a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 16324a3fd211SDave Hansen { 1633d57999e1SDave Hansen /* 16344a3fd211SDave Hansen * We'll never write to the fs underlying 16354a3fd211SDave Hansen * a device file. 16364a3fd211SDave Hansen */ 16374a3fd211SDave Hansen if (special_file(inode->i_mode)) 16384a3fd211SDave Hansen return 0; 16394a3fd211SDave Hansen return (flag & O_TRUNC); 16404a3fd211SDave Hansen } 16414a3fd211SDave Hansen 16424a3fd211SDave Hansen /* 16434a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16444a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16454a3fd211SDave Hansen * open_to_namei_flags() for more details. 16461da177e4SLinus Torvalds */ 1647a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 1648a70e65dfSChristoph Hellwig int open_flag, int mode) 16491da177e4SLinus Torvalds { 16504a3fd211SDave Hansen struct file *filp; 1651a70e65dfSChristoph Hellwig struct nameidata nd; 1652834f2a4aSTrond Myklebust int acc_mode, error; 16534e7506e4SAl Viro struct path path; 16541da177e4SLinus Torvalds struct dentry *dir; 16551da177e4SLinus Torvalds int count = 0; 16564a3fd211SDave Hansen int will_write; 1657d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16581da177e4SLinus Torvalds 1659b77b0646SAl Viro acc_mode = MAY_OPEN | ACC_MODE(flag); 16601da177e4SLinus Torvalds 1661834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1662834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1663834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1664834f2a4aSTrond Myklebust 16651da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 16661da177e4SLinus Torvalds access from general write access. */ 16671da177e4SLinus Torvalds if (flag & O_APPEND) 16681da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 16691da177e4SLinus Torvalds 16701da177e4SLinus Torvalds /* 16711da177e4SLinus Torvalds * The simplest case - just a plain lookup. 16721da177e4SLinus Torvalds */ 16731da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 16745590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1675a70e65dfSChristoph Hellwig &nd, flag); 16761da177e4SLinus Torvalds if (error) 1677a70e65dfSChristoph Hellwig return ERR_PTR(error); 16781da177e4SLinus Torvalds goto ok; 16791da177e4SLinus Torvalds } 16801da177e4SLinus Torvalds 16811da177e4SLinus Torvalds /* 16821da177e4SLinus Torvalds * Create - we need to know the parent. 16831da177e4SLinus Torvalds */ 16848737f3a1SAl Viro error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 16851da177e4SLinus Torvalds if (error) 1686a70e65dfSChristoph Hellwig return ERR_PTR(error); 16871da177e4SLinus Torvalds 16881da177e4SLinus Torvalds /* 16891da177e4SLinus Torvalds * We have the parent and last component. First of all, check 16901da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 16911da177e4SLinus Torvalds * will not do. 16921da177e4SLinus Torvalds */ 16931da177e4SLinus Torvalds error = -EISDIR; 1694a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 16958737f3a1SAl Viro goto exit_parent; 16961da177e4SLinus Torvalds 16978737f3a1SAl Viro error = -ENFILE; 16988737f3a1SAl Viro filp = get_empty_filp(); 16998737f3a1SAl Viro if (filp == NULL) 17008737f3a1SAl Viro goto exit_parent; 17018737f3a1SAl Viro nd.intent.open.file = filp; 17028737f3a1SAl Viro nd.intent.open.flags = flag; 17038737f3a1SAl Viro nd.intent.open.create_mode = mode; 1704a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1705a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 17068737f3a1SAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; 17073516586aSAl Viro if (flag & O_EXCL) 17083516586aSAl Viro nd.flags |= LOOKUP_EXCL; 17091b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1710a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1711a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 17121da177e4SLinus Torvalds 17131da177e4SLinus Torvalds do_last: 17144e7506e4SAl Viro error = PTR_ERR(path.dentry); 17154e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17161b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17171da177e4SLinus Torvalds goto exit; 17181da177e4SLinus Torvalds } 17191da177e4SLinus Torvalds 1720a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1721a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17224a3fd211SDave Hansen goto exit_mutex_unlock; 17234af4c52fSOleg Drokin } 17244af4c52fSOleg Drokin 17251da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17264e7506e4SAl Viro if (!path.dentry->d_inode) { 17274a3fd211SDave Hansen /* 17284a3fd211SDave Hansen * This write is needed to ensure that a 17294a3fd211SDave Hansen * ro->rw transition does not occur between 17304a3fd211SDave Hansen * the time when the file is created and when 17314a3fd211SDave Hansen * a permanent write count is taken through 17324a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17334a3fd211SDave Hansen */ 17344a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17351da177e4SLinus Torvalds if (error) 17364a3fd211SDave Hansen goto exit_mutex_unlock; 17374a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 17384a3fd211SDave Hansen if (error) { 17394a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17401da177e4SLinus Torvalds goto exit; 17414a3fd211SDave Hansen } 17424a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17434a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17444a3fd211SDave Hansen return filp; 17451da177e4SLinus Torvalds } 17461da177e4SLinus Torvalds 17471da177e4SLinus Torvalds /* 17481da177e4SLinus Torvalds * It already exists. 17491da177e4SLinus Torvalds */ 17501b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17515a190ae6SAl Viro audit_inode(pathname, path.dentry); 17521da177e4SLinus Torvalds 17531da177e4SLinus Torvalds error = -EEXIST; 17541da177e4SLinus Torvalds if (flag & O_EXCL) 17551da177e4SLinus Torvalds goto exit_dput; 17561da177e4SLinus Torvalds 1757e13b210fSAl Viro if (__follow_mount(&path)) { 17581da177e4SLinus Torvalds error = -ELOOP; 1759ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1760ba7a4c1aSAl Viro goto exit_dput; 17611da177e4SLinus Torvalds } 17623e2efce0SAmy Griffis 17631da177e4SLinus Torvalds error = -ENOENT; 17644e7506e4SAl Viro if (!path.dentry->d_inode) 17651da177e4SLinus Torvalds goto exit_dput; 17664e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 17671da177e4SLinus Torvalds goto do_link; 17681da177e4SLinus Torvalds 1769a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 17701da177e4SLinus Torvalds error = -EISDIR; 17714e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 17721da177e4SLinus Torvalds goto exit; 17731da177e4SLinus Torvalds ok: 17744a3fd211SDave Hansen /* 17754a3fd211SDave Hansen * Consider: 17764a3fd211SDave Hansen * 1. may_open() truncates a file 17774a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 17784a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 17794a3fd211SDave Hansen * the ro mount. 17804a3fd211SDave Hansen * That would be inconsistent, and should 17814a3fd211SDave Hansen * be avoided. Taking this mnt write here 17824a3fd211SDave Hansen * ensures that (2) can not occur. 17834a3fd211SDave Hansen */ 17844a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 17854a3fd211SDave Hansen if (will_write) { 17864a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17871da177e4SLinus Torvalds if (error) 17881da177e4SLinus Torvalds goto exit; 17894a3fd211SDave Hansen } 17904a3fd211SDave Hansen error = may_open(&nd, acc_mode, flag); 17914a3fd211SDave Hansen if (error) { 17924a3fd211SDave Hansen if (will_write) 17934a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17944a3fd211SDave Hansen goto exit; 17954a3fd211SDave Hansen } 17964a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17974a3fd211SDave Hansen /* 17984a3fd211SDave Hansen * It is now safe to drop the mnt write 17994a3fd211SDave Hansen * because the filp has had a write taken 18004a3fd211SDave Hansen * on its behalf. 18014a3fd211SDave Hansen */ 18024a3fd211SDave Hansen if (will_write) 18034a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18044a3fd211SDave Hansen return filp; 18051da177e4SLinus Torvalds 18064a3fd211SDave Hansen exit_mutex_unlock: 18074a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 18081da177e4SLinus Torvalds exit_dput: 1809a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 18101da177e4SLinus Torvalds exit: 1811a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1812a70e65dfSChristoph Hellwig release_open_intent(&nd); 18138737f3a1SAl Viro exit_parent: 1814a70e65dfSChristoph Hellwig path_put(&nd.path); 1815a70e65dfSChristoph Hellwig return ERR_PTR(error); 18161da177e4SLinus Torvalds 18171da177e4SLinus Torvalds do_link: 18181da177e4SLinus Torvalds error = -ELOOP; 18191da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18201da177e4SLinus Torvalds goto exit_dput; 18211da177e4SLinus Torvalds /* 18221da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18231da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18241da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18251da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18261da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18271da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18281da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18291da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18301da177e4SLinus Torvalds */ 1831a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1832a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18331da177e4SLinus Torvalds if (error) 18341da177e4SLinus Torvalds goto exit_dput; 1835a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1836de459215SKirill Korotaev if (error) { 1837de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1838de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1839de459215SKirill Korotaev * with "intent.open". 1840de459215SKirill Korotaev */ 1841a70e65dfSChristoph Hellwig release_open_intent(&nd); 1842a70e65dfSChristoph Hellwig return ERR_PTR(error); 1843de459215SKirill Korotaev } 1844a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1845a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18461da177e4SLinus Torvalds goto ok; 18471da177e4SLinus Torvalds error = -EISDIR; 1848a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18491da177e4SLinus Torvalds goto exit; 1850a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1851a70e65dfSChristoph Hellwig __putname(nd.last.name); 18521da177e4SLinus Torvalds goto exit; 18531da177e4SLinus Torvalds } 18541da177e4SLinus Torvalds error = -ELOOP; 18551da177e4SLinus Torvalds if (count++==32) { 1856a70e65dfSChristoph Hellwig __putname(nd.last.name); 18571da177e4SLinus Torvalds goto exit; 18581da177e4SLinus Torvalds } 1859a70e65dfSChristoph Hellwig dir = nd.path.dentry; 18601b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1861a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1862a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1863a70e65dfSChristoph Hellwig __putname(nd.last.name); 18641da177e4SLinus Torvalds goto do_last; 18651da177e4SLinus Torvalds } 18661da177e4SLinus Torvalds 18671da177e4SLinus Torvalds /** 1868a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1869a70e65dfSChristoph Hellwig * 1870a70e65dfSChristoph Hellwig * @filename: path to open 1871a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1872a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1873a70e65dfSChristoph Hellwig * 1874a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1875a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1876a70e65dfSChristoph Hellwig * along, nothing to see here.. 1877a70e65dfSChristoph Hellwig */ 1878a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1879a70e65dfSChristoph Hellwig { 1880a70e65dfSChristoph Hellwig return do_filp_open(AT_FDCWD, filename, flags, mode); 1881a70e65dfSChristoph Hellwig } 1882a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1883a70e65dfSChristoph Hellwig 1884a70e65dfSChristoph Hellwig /** 18851da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 18861da177e4SLinus Torvalds * @nd: nameidata info 18871da177e4SLinus Torvalds * @is_dir: directory flag 18881da177e4SLinus Torvalds * 18891da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 18901da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1891c663e5d8SChristoph Hellwig * 18924ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 18931da177e4SLinus Torvalds */ 18941da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 18951da177e4SLinus Torvalds { 1896c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 18971da177e4SLinus Torvalds 18984ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1899c663e5d8SChristoph Hellwig /* 1900c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1901c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1902c663e5d8SChristoph Hellwig */ 19031da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19041da177e4SLinus Torvalds goto fail; 19051da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 19063516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1907a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1908c663e5d8SChristoph Hellwig 1909c663e5d8SChristoph Hellwig /* 1910c663e5d8SChristoph Hellwig * Do the final lookup. 1911c663e5d8SChristoph Hellwig */ 191249705b77SChristoph Hellwig dentry = lookup_hash(nd); 19131da177e4SLinus Torvalds if (IS_ERR(dentry)) 19141da177e4SLinus Torvalds goto fail; 1915c663e5d8SChristoph Hellwig 1916e9baf6e5SAl Viro if (dentry->d_inode) 1917e9baf6e5SAl Viro goto eexist; 1918c663e5d8SChristoph Hellwig /* 1919c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1920c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1921c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1922c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1923c663e5d8SChristoph Hellwig */ 1924e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19251da177e4SLinus Torvalds dput(dentry); 19261da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1927e9baf6e5SAl Viro } 1928e9baf6e5SAl Viro return dentry; 1929e9baf6e5SAl Viro eexist: 1930e9baf6e5SAl Viro dput(dentry); 1931e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19321da177e4SLinus Torvalds fail: 19331da177e4SLinus Torvalds return dentry; 19341da177e4SLinus Torvalds } 1935f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19361da177e4SLinus Torvalds 19371da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19381da177e4SLinus Torvalds { 1939a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19401da177e4SLinus Torvalds 19411da177e4SLinus Torvalds if (error) 19421da177e4SLinus Torvalds return error; 19431da177e4SLinus Torvalds 19441da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19451da177e4SLinus Torvalds return -EPERM; 19461da177e4SLinus Torvalds 19471da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 19481da177e4SLinus Torvalds return -EPERM; 19491da177e4SLinus Torvalds 195008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 195108ce5f16SSerge E. Hallyn if (error) 195208ce5f16SSerge E. Hallyn return error; 195308ce5f16SSerge E. Hallyn 19541da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19551da177e4SLinus Torvalds if (error) 19561da177e4SLinus Torvalds return error; 19571da177e4SLinus Torvalds 19581da177e4SLinus Torvalds DQUOT_INIT(dir); 19591da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1960a74574aaSStephen Smalley if (!error) 1961f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19621da177e4SLinus Torvalds return error; 19631da177e4SLinus Torvalds } 19641da177e4SLinus Torvalds 1965463c3197SDave Hansen static int may_mknod(mode_t mode) 1966463c3197SDave Hansen { 1967463c3197SDave Hansen switch (mode & S_IFMT) { 1968463c3197SDave Hansen case S_IFREG: 1969463c3197SDave Hansen case S_IFCHR: 1970463c3197SDave Hansen case S_IFBLK: 1971463c3197SDave Hansen case S_IFIFO: 1972463c3197SDave Hansen case S_IFSOCK: 1973463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 1974463c3197SDave Hansen return 0; 1975463c3197SDave Hansen case S_IFDIR: 1976463c3197SDave Hansen return -EPERM; 1977463c3197SDave Hansen default: 1978463c3197SDave Hansen return -EINVAL; 1979463c3197SDave Hansen } 1980463c3197SDave Hansen } 1981463c3197SDave Hansen 19825590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 19835590ff0dSUlrich Drepper unsigned dev) 19841da177e4SLinus Torvalds { 19852ad94ae6SAl Viro int error; 19861da177e4SLinus Torvalds char *tmp; 19871da177e4SLinus Torvalds struct dentry *dentry; 19881da177e4SLinus Torvalds struct nameidata nd; 19891da177e4SLinus Torvalds 19901da177e4SLinus Torvalds if (S_ISDIR(mode)) 19911da177e4SLinus Torvalds return -EPERM; 19921da177e4SLinus Torvalds 19932ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 19941da177e4SLinus Torvalds if (error) 19952ad94ae6SAl Viro return error; 19962ad94ae6SAl Viro 19971da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 1998463c3197SDave Hansen if (IS_ERR(dentry)) { 19991da177e4SLinus Torvalds error = PTR_ERR(dentry); 2000463c3197SDave Hansen goto out_unlock; 2001463c3197SDave Hansen } 20024ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20031da177e4SLinus Torvalds mode &= ~current->fs->umask; 2004463c3197SDave Hansen error = may_mknod(mode); 2005463c3197SDave Hansen if (error) 2006463c3197SDave Hansen goto out_dput; 2007463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2008463c3197SDave Hansen if (error) 2009463c3197SDave Hansen goto out_dput; 20101da177e4SLinus Torvalds switch (mode & S_IFMT) { 20111da177e4SLinus Torvalds case 0: case S_IFREG: 20124ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20131da177e4SLinus Torvalds break; 20141da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20154ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20161da177e4SLinus Torvalds new_decode_dev(dev)); 20171da177e4SLinus Torvalds break; 20181da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20194ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20201da177e4SLinus Torvalds break; 20211da177e4SLinus Torvalds } 2022463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2023463c3197SDave Hansen out_dput: 20241da177e4SLinus Torvalds dput(dentry); 2025463c3197SDave Hansen out_unlock: 20264ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20271d957f9bSJan Blunck path_put(&nd.path); 20281da177e4SLinus Torvalds putname(tmp); 20291da177e4SLinus Torvalds 20301da177e4SLinus Torvalds return error; 20311da177e4SLinus Torvalds } 20321da177e4SLinus Torvalds 20335590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 20345590ff0dSUlrich Drepper { 20355590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20365590ff0dSUlrich Drepper } 20375590ff0dSUlrich Drepper 20381da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20391da177e4SLinus Torvalds { 2040a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20411da177e4SLinus Torvalds 20421da177e4SLinus Torvalds if (error) 20431da177e4SLinus Torvalds return error; 20441da177e4SLinus Torvalds 20451da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 20461da177e4SLinus Torvalds return -EPERM; 20471da177e4SLinus Torvalds 20481da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20491da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20501da177e4SLinus Torvalds if (error) 20511da177e4SLinus Torvalds return error; 20521da177e4SLinus Torvalds 20531da177e4SLinus Torvalds DQUOT_INIT(dir); 20541da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2055a74574aaSStephen Smalley if (!error) 2056f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20571da177e4SLinus Torvalds return error; 20581da177e4SLinus Torvalds } 20591da177e4SLinus Torvalds 20605590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 20611da177e4SLinus Torvalds { 20621da177e4SLinus Torvalds int error = 0; 20631da177e4SLinus Torvalds char * tmp; 20646902d925SDave Hansen struct dentry *dentry; 20656902d925SDave Hansen struct nameidata nd; 20661da177e4SLinus Torvalds 20672ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 20682ad94ae6SAl Viro if (error) 20696902d925SDave Hansen goto out_err; 20701da177e4SLinus Torvalds 20711da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20721da177e4SLinus Torvalds error = PTR_ERR(dentry); 20736902d925SDave Hansen if (IS_ERR(dentry)) 20746902d925SDave Hansen goto out_unlock; 20756902d925SDave Hansen 20764ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20771da177e4SLinus Torvalds mode &= ~current->fs->umask; 2078463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2079463c3197SDave Hansen if (error) 2080463c3197SDave Hansen goto out_dput; 20814ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2082463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2083463c3197SDave Hansen out_dput: 20841da177e4SLinus Torvalds dput(dentry); 20856902d925SDave Hansen out_unlock: 20864ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20871d957f9bSJan Blunck path_put(&nd.path); 20881da177e4SLinus Torvalds putname(tmp); 20896902d925SDave Hansen out_err: 20901da177e4SLinus Torvalds return error; 20911da177e4SLinus Torvalds } 20921da177e4SLinus Torvalds 20935590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 20945590ff0dSUlrich Drepper { 20955590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 20965590ff0dSUlrich Drepper } 20975590ff0dSUlrich Drepper 20981da177e4SLinus Torvalds /* 20991da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21001da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21011da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 21021da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21031da177e4SLinus Torvalds * 21041da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21051da177e4SLinus Torvalds * do a 21061da177e4SLinus Torvalds * 21071da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21081da177e4SLinus Torvalds * return -EBUSY; 21091da177e4SLinus Torvalds * 21101da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21111da177e4SLinus Torvalds * that is still in use by something else.. 21121da177e4SLinus Torvalds */ 21131da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21141da177e4SLinus Torvalds { 21151da177e4SLinus Torvalds dget(dentry); 21161da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21171da177e4SLinus Torvalds spin_lock(&dcache_lock); 21181da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21191da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21201da177e4SLinus Torvalds __d_drop(dentry); 21211da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21221da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21231da177e4SLinus Torvalds } 21241da177e4SLinus Torvalds 21251da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21261da177e4SLinus Torvalds { 21271da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21281da177e4SLinus Torvalds 21291da177e4SLinus Torvalds if (error) 21301da177e4SLinus Torvalds return error; 21311da177e4SLinus Torvalds 21321da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 21331da177e4SLinus Torvalds return -EPERM; 21341da177e4SLinus Torvalds 21351da177e4SLinus Torvalds DQUOT_INIT(dir); 21361da177e4SLinus Torvalds 21371b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21381da177e4SLinus Torvalds dentry_unhash(dentry); 21391da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21401da177e4SLinus Torvalds error = -EBUSY; 21411da177e4SLinus Torvalds else { 21421da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21431da177e4SLinus Torvalds if (!error) { 21441da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21451da177e4SLinus Torvalds if (!error) 21461da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21471da177e4SLinus Torvalds } 21481da177e4SLinus Torvalds } 21491b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21501da177e4SLinus Torvalds if (!error) { 21511da177e4SLinus Torvalds d_delete(dentry); 21521da177e4SLinus Torvalds } 21531da177e4SLinus Torvalds dput(dentry); 21541da177e4SLinus Torvalds 21551da177e4SLinus Torvalds return error; 21561da177e4SLinus Torvalds } 21571da177e4SLinus Torvalds 21585590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21591da177e4SLinus Torvalds { 21601da177e4SLinus Torvalds int error = 0; 21611da177e4SLinus Torvalds char * name; 21621da177e4SLinus Torvalds struct dentry *dentry; 21631da177e4SLinus Torvalds struct nameidata nd; 21641da177e4SLinus Torvalds 21652ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 21661da177e4SLinus Torvalds if (error) 21672ad94ae6SAl Viro return error; 21681da177e4SLinus Torvalds 21691da177e4SLinus Torvalds switch(nd.last_type) { 21701da177e4SLinus Torvalds case LAST_DOTDOT: 21711da177e4SLinus Torvalds error = -ENOTEMPTY; 21721da177e4SLinus Torvalds goto exit1; 21731da177e4SLinus Torvalds case LAST_DOT: 21741da177e4SLinus Torvalds error = -EINVAL; 21751da177e4SLinus Torvalds goto exit1; 21761da177e4SLinus Torvalds case LAST_ROOT: 21771da177e4SLinus Torvalds error = -EBUSY; 21781da177e4SLinus Torvalds goto exit1; 21791da177e4SLinus Torvalds } 21800612d9fbSOGAWA Hirofumi 21810612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 21820612d9fbSOGAWA Hirofumi 21834ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 218449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 21851da177e4SLinus Torvalds error = PTR_ERR(dentry); 21866902d925SDave Hansen if (IS_ERR(dentry)) 21876902d925SDave Hansen goto exit2; 21880622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 21890622753bSDave Hansen if (error) 21900622753bSDave Hansen goto exit3; 21914ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 21920622753bSDave Hansen mnt_drop_write(nd.path.mnt); 21930622753bSDave Hansen exit3: 21941da177e4SLinus Torvalds dput(dentry); 21956902d925SDave Hansen exit2: 21964ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21971da177e4SLinus Torvalds exit1: 21981d957f9bSJan Blunck path_put(&nd.path); 21991da177e4SLinus Torvalds putname(name); 22001da177e4SLinus Torvalds return error; 22011da177e4SLinus Torvalds } 22021da177e4SLinus Torvalds 22035590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 22045590ff0dSUlrich Drepper { 22055590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22065590ff0dSUlrich Drepper } 22075590ff0dSUlrich Drepper 22081da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22091da177e4SLinus Torvalds { 22101da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22111da177e4SLinus Torvalds 22121da177e4SLinus Torvalds if (error) 22131da177e4SLinus Torvalds return error; 22141da177e4SLinus Torvalds 22151da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 22161da177e4SLinus Torvalds return -EPERM; 22171da177e4SLinus Torvalds 22181da177e4SLinus Torvalds DQUOT_INIT(dir); 22191da177e4SLinus Torvalds 22201b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22211da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22221da177e4SLinus Torvalds error = -EBUSY; 22231da177e4SLinus Torvalds else { 22241da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22251da177e4SLinus Torvalds if (!error) 22261da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22271da177e4SLinus Torvalds } 22281b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22291da177e4SLinus Torvalds 22301da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22311da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2232ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22331da177e4SLinus Torvalds d_delete(dentry); 22341da177e4SLinus Torvalds } 22350eeca283SRobert Love 22361da177e4SLinus Torvalds return error; 22371da177e4SLinus Torvalds } 22381da177e4SLinus Torvalds 22391da177e4SLinus Torvalds /* 22401da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22411b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22421da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22431da177e4SLinus Torvalds * while waiting on the I/O. 22441da177e4SLinus Torvalds */ 22455590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22461da177e4SLinus Torvalds { 22472ad94ae6SAl Viro int error; 22481da177e4SLinus Torvalds char *name; 22491da177e4SLinus Torvalds struct dentry *dentry; 22501da177e4SLinus Torvalds struct nameidata nd; 22511da177e4SLinus Torvalds struct inode *inode = NULL; 22521da177e4SLinus Torvalds 22532ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22541da177e4SLinus Torvalds if (error) 22552ad94ae6SAl Viro return error; 22562ad94ae6SAl Viro 22571da177e4SLinus Torvalds error = -EISDIR; 22581da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22591da177e4SLinus Torvalds goto exit1; 22600612d9fbSOGAWA Hirofumi 22610612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22620612d9fbSOGAWA Hirofumi 22634ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 226449705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22651da177e4SLinus Torvalds error = PTR_ERR(dentry); 22661da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22671da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 22681da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 22691da177e4SLinus Torvalds goto slashes; 22701da177e4SLinus Torvalds inode = dentry->d_inode; 22711da177e4SLinus Torvalds if (inode) 22721da177e4SLinus Torvalds atomic_inc(&inode->i_count); 22730622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22740622753bSDave Hansen if (error) 22750622753bSDave Hansen goto exit2; 22764ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 22770622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22781da177e4SLinus Torvalds exit2: 22791da177e4SLinus Torvalds dput(dentry); 22801da177e4SLinus Torvalds } 22814ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22821da177e4SLinus Torvalds if (inode) 22831da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 22841da177e4SLinus Torvalds exit1: 22851d957f9bSJan Blunck path_put(&nd.path); 22861da177e4SLinus Torvalds putname(name); 22871da177e4SLinus Torvalds return error; 22881da177e4SLinus Torvalds 22891da177e4SLinus Torvalds slashes: 22901da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 22911da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 22921da177e4SLinus Torvalds goto exit2; 22931da177e4SLinus Torvalds } 22941da177e4SLinus Torvalds 22955590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 22965590ff0dSUlrich Drepper { 22975590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 22985590ff0dSUlrich Drepper return -EINVAL; 22995590ff0dSUlrich Drepper 23005590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23015590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23025590ff0dSUlrich Drepper 23035590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23045590ff0dSUlrich Drepper } 23055590ff0dSUlrich Drepper 23065590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 23075590ff0dSUlrich Drepper { 23085590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23095590ff0dSUlrich Drepper } 23105590ff0dSUlrich Drepper 2311db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23121da177e4SLinus Torvalds { 2313a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23141da177e4SLinus Torvalds 23151da177e4SLinus Torvalds if (error) 23161da177e4SLinus Torvalds return error; 23171da177e4SLinus Torvalds 23181da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 23191da177e4SLinus Torvalds return -EPERM; 23201da177e4SLinus Torvalds 23211da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23221da177e4SLinus Torvalds if (error) 23231da177e4SLinus Torvalds return error; 23241da177e4SLinus Torvalds 23251da177e4SLinus Torvalds DQUOT_INIT(dir); 23261da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2327a74574aaSStephen Smalley if (!error) 2328f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23291da177e4SLinus Torvalds return error; 23301da177e4SLinus Torvalds } 23311da177e4SLinus Torvalds 23325590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 23335590ff0dSUlrich Drepper int newdfd, const char __user *newname) 23341da177e4SLinus Torvalds { 23352ad94ae6SAl Viro int error; 23361da177e4SLinus Torvalds char *from; 23371da177e4SLinus Torvalds char *to; 23386902d925SDave Hansen struct dentry *dentry; 23396902d925SDave Hansen struct nameidata nd; 23401da177e4SLinus Torvalds 23411da177e4SLinus Torvalds from = getname(oldname); 23421da177e4SLinus Torvalds if (IS_ERR(from)) 23431da177e4SLinus Torvalds return PTR_ERR(from); 23442ad94ae6SAl Viro 23452ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 23462ad94ae6SAl Viro if (error) 23476902d925SDave Hansen goto out_putname; 23481da177e4SLinus Torvalds 23491da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23501da177e4SLinus Torvalds error = PTR_ERR(dentry); 23516902d925SDave Hansen if (IS_ERR(dentry)) 23526902d925SDave Hansen goto out_unlock; 23536902d925SDave Hansen 235475c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 235575c3f29dSDave Hansen if (error) 235675c3f29dSDave Hansen goto out_dput; 2357db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 235875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 235975c3f29dSDave Hansen out_dput: 23601da177e4SLinus Torvalds dput(dentry); 23616902d925SDave Hansen out_unlock: 23624ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23631d957f9bSJan Blunck path_put(&nd.path); 23641da177e4SLinus Torvalds putname(to); 23656902d925SDave Hansen out_putname: 23661da177e4SLinus Torvalds putname(from); 23671da177e4SLinus Torvalds return error; 23681da177e4SLinus Torvalds } 23691da177e4SLinus Torvalds 23705590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 23715590ff0dSUlrich Drepper { 23725590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 23735590ff0dSUlrich Drepper } 23745590ff0dSUlrich Drepper 23751da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 23761da177e4SLinus Torvalds { 23771da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 23781da177e4SLinus Torvalds int error; 23791da177e4SLinus Torvalds 23801da177e4SLinus Torvalds if (!inode) 23811da177e4SLinus Torvalds return -ENOENT; 23821da177e4SLinus Torvalds 2383a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 23841da177e4SLinus Torvalds if (error) 23851da177e4SLinus Torvalds return error; 23861da177e4SLinus Torvalds 23871da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 23881da177e4SLinus Torvalds return -EXDEV; 23891da177e4SLinus Torvalds 23901da177e4SLinus Torvalds /* 23911da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 23921da177e4SLinus Torvalds */ 23931da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 23941da177e4SLinus Torvalds return -EPERM; 23951da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 23961da177e4SLinus Torvalds return -EPERM; 23977e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 23981da177e4SLinus Torvalds return -EPERM; 23991da177e4SLinus Torvalds 24001da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24011da177e4SLinus Torvalds if (error) 24021da177e4SLinus Torvalds return error; 24031da177e4SLinus Torvalds 24047e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24051da177e4SLinus Torvalds DQUOT_INIT(dir); 24061da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24077e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2408e31e14ecSStephen Smalley if (!error) 24097e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24101da177e4SLinus Torvalds return error; 24111da177e4SLinus Torvalds } 24121da177e4SLinus Torvalds 24131da177e4SLinus Torvalds /* 24141da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24151da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24161da177e4SLinus Torvalds * newname. --KAB 24171da177e4SLinus Torvalds * 24181da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24191da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24201da177e4SLinus Torvalds * and other special files. --ADM 24211da177e4SLinus Torvalds */ 24225590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2423c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2424c04030e1SUlrich Drepper int flags) 24251da177e4SLinus Torvalds { 24261da177e4SLinus Torvalds struct dentry *new_dentry; 24272d8f3038SAl Viro struct nameidata nd; 24282d8f3038SAl Viro struct path old_path; 24291da177e4SLinus Torvalds int error; 24301da177e4SLinus Torvalds char *to; 24311da177e4SLinus Torvalds 243245c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2433c04030e1SUlrich Drepper return -EINVAL; 2434c04030e1SUlrich Drepper 24352d8f3038SAl Viro error = user_path_at(olddfd, oldname, 243645c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24372d8f3038SAl Viro &old_path); 24381da177e4SLinus Torvalds if (error) 24392ad94ae6SAl Viro return error; 24402ad94ae6SAl Viro 24412ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24421da177e4SLinus Torvalds if (error) 24431da177e4SLinus Torvalds goto out; 24441da177e4SLinus Torvalds error = -EXDEV; 24452d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 24461da177e4SLinus Torvalds goto out_release; 24471da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24481da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24496902d925SDave Hansen if (IS_ERR(new_dentry)) 24506902d925SDave Hansen goto out_unlock; 245175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 245275c3f29dSDave Hansen if (error) 245375c3f29dSDave Hansen goto out_dput; 24542d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 245575c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 245675c3f29dSDave Hansen out_dput: 24571da177e4SLinus Torvalds dput(new_dentry); 24586902d925SDave Hansen out_unlock: 24594ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24601da177e4SLinus Torvalds out_release: 24611d957f9bSJan Blunck path_put(&nd.path); 24622ad94ae6SAl Viro putname(to); 24631da177e4SLinus Torvalds out: 24642d8f3038SAl Viro path_put(&old_path); 24651da177e4SLinus Torvalds 24661da177e4SLinus Torvalds return error; 24671da177e4SLinus Torvalds } 24681da177e4SLinus Torvalds 24695590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 24705590ff0dSUlrich Drepper { 2471c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 24725590ff0dSUlrich Drepper } 24735590ff0dSUlrich Drepper 24741da177e4SLinus Torvalds /* 24751da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 24761da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 24771da177e4SLinus Torvalds * Problems: 24781da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 24791da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 24801da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2481a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 24821da177e4SLinus Torvalds * story. 24831da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 24841b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 24851da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 24861da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2487a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 24881da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 24891da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 24901da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2491a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 24921da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 24931da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 24941da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 24951da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 24961da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 24971da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 24981da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 24991da177e4SLinus Torvalds * trick as in rmdir(). 25001da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25011b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25021da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25031b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25041da177e4SLinus Torvalds * locking]. 25051da177e4SLinus Torvalds */ 250675c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25071da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25081da177e4SLinus Torvalds { 25091da177e4SLinus Torvalds int error = 0; 25101da177e4SLinus Torvalds struct inode *target; 25111da177e4SLinus Torvalds 25121da177e4SLinus Torvalds /* 25131da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25141da177e4SLinus Torvalds * we'll need to flip '..'. 25151da177e4SLinus Torvalds */ 25161da177e4SLinus Torvalds if (new_dir != old_dir) { 2517f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25181da177e4SLinus Torvalds if (error) 25191da177e4SLinus Torvalds return error; 25201da177e4SLinus Torvalds } 25211da177e4SLinus Torvalds 25221da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25231da177e4SLinus Torvalds if (error) 25241da177e4SLinus Torvalds return error; 25251da177e4SLinus Torvalds 25261da177e4SLinus Torvalds target = new_dentry->d_inode; 25271da177e4SLinus Torvalds if (target) { 25281b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25291da177e4SLinus Torvalds dentry_unhash(new_dentry); 25301da177e4SLinus Torvalds } 25311da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25321da177e4SLinus Torvalds error = -EBUSY; 25331da177e4SLinus Torvalds else 25341da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25351da177e4SLinus Torvalds if (target) { 25361da177e4SLinus Torvalds if (!error) 25371da177e4SLinus Torvalds target->i_flags |= S_DEAD; 25381b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25391da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 25401da177e4SLinus Torvalds d_rehash(new_dentry); 25411da177e4SLinus Torvalds dput(new_dentry); 25421da177e4SLinus Torvalds } 2543e31e14ecSStephen Smalley if (!error) 2544349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25451da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25461da177e4SLinus Torvalds return error; 25471da177e4SLinus Torvalds } 25481da177e4SLinus Torvalds 254975c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25501da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25511da177e4SLinus Torvalds { 25521da177e4SLinus Torvalds struct inode *target; 25531da177e4SLinus Torvalds int error; 25541da177e4SLinus Torvalds 25551da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25561da177e4SLinus Torvalds if (error) 25571da177e4SLinus Torvalds return error; 25581da177e4SLinus Torvalds 25591da177e4SLinus Torvalds dget(new_dentry); 25601da177e4SLinus Torvalds target = new_dentry->d_inode; 25611da177e4SLinus Torvalds if (target) 25621b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25631da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25641da177e4SLinus Torvalds error = -EBUSY; 25651da177e4SLinus Torvalds else 25661da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25671da177e4SLinus Torvalds if (!error) { 2568349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25691da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 25701da177e4SLinus Torvalds } 25711da177e4SLinus Torvalds if (target) 25721b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25731da177e4SLinus Torvalds dput(new_dentry); 25741da177e4SLinus Torvalds return error; 25751da177e4SLinus Torvalds } 25761da177e4SLinus Torvalds 25771da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 25781da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25791da177e4SLinus Torvalds { 25801da177e4SLinus Torvalds int error; 25811da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 25820eeca283SRobert Love const char *old_name; 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 25851da177e4SLinus Torvalds return 0; 25861da177e4SLinus Torvalds 25871da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 25881da177e4SLinus Torvalds if (error) 25891da177e4SLinus Torvalds return error; 25901da177e4SLinus Torvalds 25911da177e4SLinus Torvalds if (!new_dentry->d_inode) 2592a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 25931da177e4SLinus Torvalds else 25941da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 25951da177e4SLinus Torvalds if (error) 25961da177e4SLinus Torvalds return error; 25971da177e4SLinus Torvalds 25981da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 25991da177e4SLinus Torvalds return -EPERM; 26001da177e4SLinus Torvalds 26011da177e4SLinus Torvalds DQUOT_INIT(old_dir); 26021da177e4SLinus Torvalds DQUOT_INIT(new_dir); 26031da177e4SLinus Torvalds 26040eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26050eeca283SRobert Love 26061da177e4SLinus Torvalds if (is_dir) 26071da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26081da177e4SLinus Torvalds else 26091da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26101da177e4SLinus Torvalds if (!error) { 26110eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 261289204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26135a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26141da177e4SLinus Torvalds } 26150eeca283SRobert Love fsnotify_oldname_free(old_name); 26160eeca283SRobert Love 26171da177e4SLinus Torvalds return error; 26181da177e4SLinus Torvalds } 26191da177e4SLinus Torvalds 26202ad94ae6SAl Viro asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 26212ad94ae6SAl Viro int newdfd, const char __user *newname) 26221da177e4SLinus Torvalds { 26231da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26241da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26251da177e4SLinus Torvalds struct dentry *trap; 26261da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26272ad94ae6SAl Viro char *from; 26282ad94ae6SAl Viro char *to; 26292ad94ae6SAl Viro int error; 26301da177e4SLinus Torvalds 26312ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26321da177e4SLinus Torvalds if (error) 26331da177e4SLinus Torvalds goto exit; 26341da177e4SLinus Torvalds 26352ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 26361da177e4SLinus Torvalds if (error) 26371da177e4SLinus Torvalds goto exit1; 26381da177e4SLinus Torvalds 26391da177e4SLinus Torvalds error = -EXDEV; 26404ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 26411da177e4SLinus Torvalds goto exit2; 26421da177e4SLinus Torvalds 26434ac91378SJan Blunck old_dir = oldnd.path.dentry; 26441da177e4SLinus Torvalds error = -EBUSY; 26451da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 26461da177e4SLinus Torvalds goto exit2; 26471da177e4SLinus Torvalds 26484ac91378SJan Blunck new_dir = newnd.path.dentry; 26491da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26501da177e4SLinus Torvalds goto exit2; 26511da177e4SLinus Torvalds 26520612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 26530612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 26544e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 26550612d9fbSOGAWA Hirofumi 26561da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 26571da177e4SLinus Torvalds 265849705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 26591da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 26601da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 26611da177e4SLinus Torvalds goto exit3; 26621da177e4SLinus Torvalds /* source must exist */ 26631da177e4SLinus Torvalds error = -ENOENT; 26641da177e4SLinus Torvalds if (!old_dentry->d_inode) 26651da177e4SLinus Torvalds goto exit4; 26661da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 26671da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 26681da177e4SLinus Torvalds error = -ENOTDIR; 26691da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 26701da177e4SLinus Torvalds goto exit4; 26711da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 26721da177e4SLinus Torvalds goto exit4; 26731da177e4SLinus Torvalds } 26741da177e4SLinus Torvalds /* source should not be ancestor of target */ 26751da177e4SLinus Torvalds error = -EINVAL; 26761da177e4SLinus Torvalds if (old_dentry == trap) 26771da177e4SLinus Torvalds goto exit4; 267849705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 26791da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 26801da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 26811da177e4SLinus Torvalds goto exit4; 26821da177e4SLinus Torvalds /* target should not be an ancestor of source */ 26831da177e4SLinus Torvalds error = -ENOTEMPTY; 26841da177e4SLinus Torvalds if (new_dentry == trap) 26851da177e4SLinus Torvalds goto exit5; 26861da177e4SLinus Torvalds 26879079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 26889079b1ebSDave Hansen if (error) 26899079b1ebSDave Hansen goto exit5; 26901da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 26911da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 26929079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 26931da177e4SLinus Torvalds exit5: 26941da177e4SLinus Torvalds dput(new_dentry); 26951da177e4SLinus Torvalds exit4: 26961da177e4SLinus Torvalds dput(old_dentry); 26971da177e4SLinus Torvalds exit3: 26981da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 26991da177e4SLinus Torvalds exit2: 27001d957f9bSJan Blunck path_put(&newnd.path); 27012ad94ae6SAl Viro putname(to); 27021da177e4SLinus Torvalds exit1: 27031d957f9bSJan Blunck path_put(&oldnd.path); 27041da177e4SLinus Torvalds putname(from); 27052ad94ae6SAl Viro exit: 27061da177e4SLinus Torvalds return error; 27071da177e4SLinus Torvalds } 27081da177e4SLinus Torvalds 27095590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 27105590ff0dSUlrich Drepper { 27115590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27125590ff0dSUlrich Drepper } 27135590ff0dSUlrich Drepper 27141da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27151da177e4SLinus Torvalds { 27161da177e4SLinus Torvalds int len; 27171da177e4SLinus Torvalds 27181da177e4SLinus Torvalds len = PTR_ERR(link); 27191da177e4SLinus Torvalds if (IS_ERR(link)) 27201da177e4SLinus Torvalds goto out; 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds len = strlen(link); 27231da177e4SLinus Torvalds if (len > (unsigned) buflen) 27241da177e4SLinus Torvalds len = buflen; 27251da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27261da177e4SLinus Torvalds len = -EFAULT; 27271da177e4SLinus Torvalds out: 27281da177e4SLinus Torvalds return len; 27291da177e4SLinus Torvalds } 27301da177e4SLinus Torvalds 27311da177e4SLinus Torvalds /* 27321da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 27331da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 27341da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 27351da177e4SLinus Torvalds */ 27361da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27371da177e4SLinus Torvalds { 27381da177e4SLinus Torvalds struct nameidata nd; 2739cc314eefSLinus Torvalds void *cookie; 2740694a1764SMarcin Slusarz int res; 2741cc314eefSLinus Torvalds 27421da177e4SLinus Torvalds nd.depth = 0; 2743cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2744694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2745694a1764SMarcin Slusarz return PTR_ERR(cookie); 2746694a1764SMarcin Slusarz 2747694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27481da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2749cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2750694a1764SMarcin Slusarz return res; 27511da177e4SLinus Torvalds } 27521da177e4SLinus Torvalds 27531da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 27541da177e4SLinus Torvalds { 27551da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 27561da177e4SLinus Torvalds } 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds /* get the link contents into pagecache */ 27591da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 27601da177e4SLinus Torvalds { 27611da177e4SLinus Torvalds struct page * page; 27621da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2763090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 27641da177e4SLinus Torvalds if (IS_ERR(page)) 27656fe6900eSNick Piggin return (char*)page; 27661da177e4SLinus Torvalds *ppage = page; 27671da177e4SLinus Torvalds return kmap(page); 27681da177e4SLinus Torvalds } 27691da177e4SLinus Torvalds 27701da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27711da177e4SLinus Torvalds { 27721da177e4SLinus Torvalds struct page *page = NULL; 27731da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 27741da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 27751da177e4SLinus Torvalds if (page) { 27761da177e4SLinus Torvalds kunmap(page); 27771da177e4SLinus Torvalds page_cache_release(page); 27781da177e4SLinus Torvalds } 27791da177e4SLinus Torvalds return res; 27801da177e4SLinus Torvalds } 27811da177e4SLinus Torvalds 2782cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 27831da177e4SLinus Torvalds { 2784cc314eefSLinus Torvalds struct page *page = NULL; 27851da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2786cc314eefSLinus Torvalds return page; 27871da177e4SLinus Torvalds } 27881da177e4SLinus Torvalds 2789cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 27901da177e4SLinus Torvalds { 2791cc314eefSLinus Torvalds struct page *page = cookie; 2792cc314eefSLinus Torvalds 2793cc314eefSLinus Torvalds if (page) { 27941da177e4SLinus Torvalds kunmap(page); 27951da177e4SLinus Torvalds page_cache_release(page); 27961da177e4SLinus Torvalds } 27971da177e4SLinus Torvalds } 27981da177e4SLinus Torvalds 27990adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 28000adb25d2SKirill Korotaev gfp_t gfp_mask) 28011da177e4SLinus Torvalds { 28021da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28030adb25d2SKirill Korotaev struct page *page; 2804afddba49SNick Piggin void *fsdata; 2805beb497abSDmitriy Monakhov int err; 28061da177e4SLinus Torvalds char *kaddr; 28071da177e4SLinus Torvalds 28087e53cac4SNeilBrown retry: 2809afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2810afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 28111da177e4SLinus Torvalds if (err) 2812afddba49SNick Piggin goto fail; 2813afddba49SNick Piggin 28141da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28151da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28161da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2817afddba49SNick Piggin 2818afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2819afddba49SNick Piggin page, fsdata); 28201da177e4SLinus Torvalds if (err < 0) 28211da177e4SLinus Torvalds goto fail; 2822afddba49SNick Piggin if (err < len-1) 2823afddba49SNick Piggin goto retry; 2824afddba49SNick Piggin 28251da177e4SLinus Torvalds mark_inode_dirty(inode); 28261da177e4SLinus Torvalds return 0; 28271da177e4SLinus Torvalds fail: 28281da177e4SLinus Torvalds return err; 28291da177e4SLinus Torvalds } 28301da177e4SLinus Torvalds 28310adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 28320adb25d2SKirill Korotaev { 28330adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 28340adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 28350adb25d2SKirill Korotaev } 28360adb25d2SKirill Korotaev 283792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 28381da177e4SLinus Torvalds .readlink = generic_readlink, 28391da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28401da177e4SLinus Torvalds .put_link = page_put_link, 28411da177e4SLinus Torvalds }; 28421da177e4SLinus Torvalds 28432d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 28441da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 28451da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 28461da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 28471da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 28481da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 28491da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 28501da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 28511da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 28521da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 28530adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 28541da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 28551da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 28561da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2857d1811465SAl Viro EXPORT_SYMBOL(kern_path); 285816f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2859f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 2860e4543eddSChristoph Hellwig EXPORT_SYMBOL(vfs_permission); 28618c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 28621da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 28631da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 28641da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 28651da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 28661da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 28671da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 28681da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 28691da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 28701da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 28711da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 28721da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 28731da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 28741da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 28751da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2876