11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/quotaops.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 341da177e4SLinus Torvalds #include <asm/uaccess.h> 351da177e4SLinus Torvalds 361da177e4SLinus Torvalds #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE]) 371da177e4SLinus Torvalds 381da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 391da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 401da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 411da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 421da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 431da177e4SLinus Torvalds * 441da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 451da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 461da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 471da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 481da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 491da177e4SLinus Torvalds * the special cases of the former code. 501da177e4SLinus Torvalds * 511da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 521da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 531da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 541da177e4SLinus Torvalds * 551da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 561da177e4SLinus Torvalds * resolution to correspond with current state of the code. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 591da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 601da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 611da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 621da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 631da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 641da177e4SLinus Torvalds */ 651da177e4SLinus Torvalds 661da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 671da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 681da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 691da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 701da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 711da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 721da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 731da177e4SLinus Torvalds * 741da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 751da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 761da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 771da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 781da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 791da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 801da177e4SLinus Torvalds * and in the old Linux semantics. 811da177e4SLinus Torvalds */ 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 841da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 851da177e4SLinus Torvalds * 861da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 871da177e4SLinus Torvalds */ 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 901da177e4SLinus Torvalds * inside the path - always follow. 911da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 921da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 931da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 941da177e4SLinus Torvalds * otherwise - don't follow. 951da177e4SLinus Torvalds * (applied in that order). 961da177e4SLinus Torvalds * 971da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 981da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 991da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1001da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1011da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1021da177e4SLinus Torvalds */ 1031da177e4SLinus Torvalds /* 1041da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 105a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1061da177e4SLinus Torvalds * any extra contention... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds 109a02f76c3SAl Viro static int __link_path_walk(const char *name, struct nameidata *nd); 110c4a7808fSJosef 'Jeff' Sipek 1111da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1121da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1131da177e4SLinus Torvalds * kernel data space before using them.. 1141da177e4SLinus Torvalds * 1151da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1161da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1171da177e4SLinus Torvalds */ 118858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1191da177e4SLinus Torvalds { 1201da177e4SLinus Torvalds int retval; 1211da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1221da177e4SLinus Torvalds 1231da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1241da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1251da177e4SLinus Torvalds return -EFAULT; 1261da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1271da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1311da177e4SLinus Torvalds if (retval > 0) { 1321da177e4SLinus Torvalds if (retval < len) 1331da177e4SLinus Torvalds return 0; 1341da177e4SLinus Torvalds return -ENAMETOOLONG; 1351da177e4SLinus Torvalds } else if (!retval) 1361da177e4SLinus Torvalds retval = -ENOENT; 1371da177e4SLinus Torvalds return retval; 1381da177e4SLinus Torvalds } 1391da177e4SLinus Torvalds 1401da177e4SLinus Torvalds char * getname(const char __user * filename) 1411da177e4SLinus Torvalds { 1421da177e4SLinus Torvalds char *tmp, *result; 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1451da177e4SLinus Torvalds tmp = __getname(); 1461da177e4SLinus Torvalds if (tmp) { 1471da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds result = tmp; 1501da177e4SLinus Torvalds if (retval < 0) { 1511da177e4SLinus Torvalds __putname(tmp); 1521da177e4SLinus Torvalds result = ERR_PTR(retval); 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds audit_getname(result); 1561da177e4SLinus Torvalds return result; 1571da177e4SLinus Torvalds } 1581da177e4SLinus Torvalds 1591da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1601da177e4SLinus Torvalds void putname(const char *name) 1611da177e4SLinus Torvalds { 1625ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1631da177e4SLinus Torvalds audit_putname(name); 1641da177e4SLinus Torvalds else 1651da177e4SLinus Torvalds __putname(name); 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1681da177e4SLinus Torvalds #endif 1691da177e4SLinus Torvalds 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds /** 1721da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 1731da177e4SLinus Torvalds * @inode: inode to check access rights for 1741da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 1751da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 1761da177e4SLinus Torvalds * 1771da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 1781da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 1791da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 1801da177e4SLinus Torvalds * are used for other things.. 1811da177e4SLinus Torvalds */ 1821da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 1831da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1841da177e4SLinus Torvalds { 1851da177e4SLinus Torvalds umode_t mode = inode->i_mode; 1861da177e4SLinus Torvalds 187e6305c43SAl Viro mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 188e6305c43SAl Viro 189da9592edSDavid Howells if (current_fsuid() == inode->i_uid) 1901da177e4SLinus Torvalds mode >>= 6; 1911da177e4SLinus Torvalds else { 1921da177e4SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1931da177e4SLinus Torvalds int error = check_acl(inode, mask); 1941da177e4SLinus Torvalds if (error == -EACCES) 1951da177e4SLinus Torvalds goto check_capabilities; 1961da177e4SLinus Torvalds else if (error != -EAGAIN) 1971da177e4SLinus Torvalds return error; 1981da177e4SLinus Torvalds } 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds if (in_group_p(inode->i_gid)) 2011da177e4SLinus Torvalds mode >>= 3; 2021da177e4SLinus Torvalds } 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds /* 2051da177e4SLinus Torvalds * If the DACs are ok we don't need any capability check. 2061da177e4SLinus Torvalds */ 207e6305c43SAl Viro if ((mask & ~mode) == 0) 2081da177e4SLinus Torvalds return 0; 2091da177e4SLinus Torvalds 2101da177e4SLinus Torvalds check_capabilities: 2111da177e4SLinus Torvalds /* 2121da177e4SLinus Torvalds * Read/write DACs are always overridable. 2131da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2141da177e4SLinus Torvalds */ 215f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2161da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2171da177e4SLinus Torvalds return 0; 2181da177e4SLinus Torvalds 2191da177e4SLinus Torvalds /* 2201da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2211da177e4SLinus Torvalds */ 2221da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2231da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2241da177e4SLinus Torvalds return 0; 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds return -EACCES; 2271da177e4SLinus Torvalds } 2281da177e4SLinus Torvalds 229cb23beb5SChristoph Hellwig /** 230cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 231cb23beb5SChristoph Hellwig * @inode: inode to check permission on 232cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 233cb23beb5SChristoph Hellwig * 234cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 235cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 236cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 237cb23beb5SChristoph Hellwig * are used for other things. 238cb23beb5SChristoph Hellwig */ 239f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2401da177e4SLinus Torvalds { 241e6305c43SAl Viro int retval; 2421da177e4SLinus Torvalds 2431da177e4SLinus Torvalds if (mask & MAY_WRITE) { 24422590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2451da177e4SLinus Torvalds 2461da177e4SLinus Torvalds /* 2471da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2481da177e4SLinus Torvalds */ 2491da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2501da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2511da177e4SLinus Torvalds return -EROFS; 2521da177e4SLinus Torvalds 2531da177e4SLinus Torvalds /* 2541da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2551da177e4SLinus Torvalds */ 2561da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2571da177e4SLinus Torvalds return -EACCES; 2581da177e4SLinus Torvalds } 2591da177e4SLinus Torvalds 260f696a365SMiklos Szeredi if (inode->i_op && inode->i_op->permission) 261b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 262f696a365SMiklos Szeredi else 263e6305c43SAl Viro retval = generic_permission(inode, mask, NULL); 264f696a365SMiklos Szeredi 2651da177e4SLinus Torvalds if (retval) 2661da177e4SLinus Torvalds return retval; 2671da177e4SLinus Torvalds 26808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 26908ce5f16SSerge E. Hallyn if (retval) 27008ce5f16SSerge E. Hallyn return retval; 27108ce5f16SSerge E. Hallyn 272e6305c43SAl Viro return security_inode_permission(inode, 273f418b006SStephen Smalley mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); 2741da177e4SLinus Torvalds } 2751da177e4SLinus Torvalds 276e4543eddSChristoph Hellwig /** 2778c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2788c744fb8SChristoph Hellwig * @file: file to check access rights for 2798c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2808c744fb8SChristoph Hellwig * 2818c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 2828c744fb8SChristoph Hellwig * file. 2838c744fb8SChristoph Hellwig * 2848c744fb8SChristoph Hellwig * Note: 2858c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 286cb23beb5SChristoph Hellwig * be done using inode_permission(). 2878c744fb8SChristoph Hellwig */ 2888c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 2898c744fb8SChristoph Hellwig { 290f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 2918c744fb8SChristoph Hellwig } 2928c744fb8SChristoph Hellwig 2931da177e4SLinus Torvalds /* 2941da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 2951da177e4SLinus Torvalds * put_write_access() releases this write permission. 2961da177e4SLinus Torvalds * This is used for regular files. 2971da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 2981da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 2991da177e4SLinus Torvalds * can have the following values: 3001da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3011da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3021da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3031da177e4SLinus Torvalds * 3041da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3051da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3061da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3071da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3081da177e4SLinus Torvalds * the inode->i_lock spinlock. 3091da177e4SLinus Torvalds */ 3101da177e4SLinus Torvalds 3111da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3121da177e4SLinus Torvalds { 3131da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3141da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3151da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3161da177e4SLinus Torvalds return -ETXTBSY; 3171da177e4SLinus Torvalds } 3181da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3191da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3201da177e4SLinus Torvalds 3211da177e4SLinus Torvalds return 0; 3221da177e4SLinus Torvalds } 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds int deny_write_access(struct file * file) 3251da177e4SLinus Torvalds { 3260f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3271da177e4SLinus Torvalds 3281da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3291da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3301da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3311da177e4SLinus Torvalds return -ETXTBSY; 3321da177e4SLinus Torvalds } 3331da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3341da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds return 0; 3371da177e4SLinus Torvalds } 3381da177e4SLinus Torvalds 3391d957f9bSJan Blunck /** 3405dd784d0SJan Blunck * path_get - get a reference to a path 3415dd784d0SJan Blunck * @path: path to get the reference to 3425dd784d0SJan Blunck * 3435dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3445dd784d0SJan Blunck */ 3455dd784d0SJan Blunck void path_get(struct path *path) 3465dd784d0SJan Blunck { 3475dd784d0SJan Blunck mntget(path->mnt); 3485dd784d0SJan Blunck dget(path->dentry); 3495dd784d0SJan Blunck } 3505dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3515dd784d0SJan Blunck 3525dd784d0SJan Blunck /** 3531d957f9bSJan Blunck * path_put - put a reference to a path 3541d957f9bSJan Blunck * @path: path to put the reference to 3551d957f9bSJan Blunck * 3561d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3571d957f9bSJan Blunck */ 3581d957f9bSJan Blunck void path_put(struct path *path) 3591da177e4SLinus Torvalds { 3601d957f9bSJan Blunck dput(path->dentry); 3611d957f9bSJan Blunck mntput(path->mnt); 3621da177e4SLinus Torvalds } 3631d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3641da177e4SLinus Torvalds 365834f2a4aSTrond Myklebust /** 366834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 367834f2a4aSTrond Myklebust * @nd: pointer to nameidata 368834f2a4aSTrond Myklebust */ 369834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 370834f2a4aSTrond Myklebust { 3710f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 372834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 373834f2a4aSTrond Myklebust else 374834f2a4aSTrond Myklebust fput(nd->intent.open.file); 375834f2a4aSTrond Myklebust } 376834f2a4aSTrond Myklebust 377bcdc5e01SIan Kent static inline struct dentry * 378bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 379bcdc5e01SIan Kent { 380bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 381bcdc5e01SIan Kent if (unlikely(status <= 0)) { 382bcdc5e01SIan Kent /* 383bcdc5e01SIan Kent * The dentry failed validation. 384bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 385bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 386bcdc5e01SIan Kent * to return a fail status. 387bcdc5e01SIan Kent */ 388bcdc5e01SIan Kent if (!status) { 389bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 390bcdc5e01SIan Kent dput(dentry); 391bcdc5e01SIan Kent dentry = NULL; 392bcdc5e01SIan Kent } 393bcdc5e01SIan Kent } else { 394bcdc5e01SIan Kent dput(dentry); 395bcdc5e01SIan Kent dentry = ERR_PTR(status); 396bcdc5e01SIan Kent } 397bcdc5e01SIan Kent } 398bcdc5e01SIan Kent return dentry; 399bcdc5e01SIan Kent } 400bcdc5e01SIan Kent 4011da177e4SLinus Torvalds /* 4021da177e4SLinus Torvalds * Internal lookup() using the new generic dcache. 4031da177e4SLinus Torvalds * SMP-safe 4041da177e4SLinus Torvalds */ 4051da177e4SLinus Torvalds static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4061da177e4SLinus Torvalds { 4071da177e4SLinus Torvalds struct dentry * dentry = __d_lookup(parent, name); 4081da177e4SLinus Torvalds 4091da177e4SLinus Torvalds /* lockess __d_lookup may fail due to concurrent d_move() 4101da177e4SLinus Torvalds * in some unrelated directory, so try with d_lookup 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds if (!dentry) 4131da177e4SLinus Torvalds dentry = d_lookup(parent, name); 4141da177e4SLinus Torvalds 415bcdc5e01SIan Kent if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 416bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 417bcdc5e01SIan Kent 4181da177e4SLinus Torvalds return dentry; 4191da177e4SLinus Torvalds } 4201da177e4SLinus Torvalds 4211da177e4SLinus Torvalds /* 4221da177e4SLinus Torvalds * Short-cut version of permission(), for calling by 4231da177e4SLinus Torvalds * path_walk(), when dcache lock is held. Combines parts 4241da177e4SLinus Torvalds * of permission() and generic_permission(), and tests ONLY for 4251da177e4SLinus Torvalds * MAY_EXEC permission. 4261da177e4SLinus Torvalds * 4271da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 4281da177e4SLinus Torvalds * short-cut DAC fails, then call permission() to do more 4291da177e4SLinus Torvalds * complete permission check. 4301da177e4SLinus Torvalds */ 431672b16b2SAl Viro static int exec_permission_lite(struct inode *inode) 4321da177e4SLinus Torvalds { 4331da177e4SLinus Torvalds umode_t mode = inode->i_mode; 4341da177e4SLinus Torvalds 4351da177e4SLinus Torvalds if (inode->i_op && inode->i_op->permission) 4361da177e4SLinus Torvalds return -EAGAIN; 4371da177e4SLinus Torvalds 438da9592edSDavid Howells if (current_fsuid() == inode->i_uid) 4391da177e4SLinus Torvalds mode >>= 6; 4401da177e4SLinus Torvalds else if (in_group_p(inode->i_gid)) 4411da177e4SLinus Torvalds mode >>= 3; 4421da177e4SLinus Torvalds 4431da177e4SLinus Torvalds if (mode & MAY_EXEC) 4441da177e4SLinus Torvalds goto ok; 4451da177e4SLinus Torvalds 4461da177e4SLinus Torvalds if ((inode->i_mode & S_IXUGO) && capable(CAP_DAC_OVERRIDE)) 4471da177e4SLinus Torvalds goto ok; 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_OVERRIDE)) 4501da177e4SLinus Torvalds goto ok; 4511da177e4SLinus Torvalds 4521da177e4SLinus Torvalds if (S_ISDIR(inode->i_mode) && capable(CAP_DAC_READ_SEARCH)) 4531da177e4SLinus Torvalds goto ok; 4541da177e4SLinus Torvalds 4551da177e4SLinus Torvalds return -EACCES; 4561da177e4SLinus Torvalds ok: 457b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4581da177e4SLinus Torvalds } 4591da177e4SLinus Torvalds 4601da177e4SLinus Torvalds /* 4611da177e4SLinus Torvalds * This is called when everything else fails, and we actually have 4621da177e4SLinus Torvalds * to go to the low-level filesystem to find out what we should do.. 4631da177e4SLinus Torvalds * 4641da177e4SLinus Torvalds * We get the directory semaphore, and after getting that we also 4651da177e4SLinus Torvalds * make sure that nobody added the entry to the dcache in the meantime.. 4661da177e4SLinus Torvalds * SMP-safe 4671da177e4SLinus Torvalds */ 4681da177e4SLinus Torvalds static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd) 4691da177e4SLinus Torvalds { 4701da177e4SLinus Torvalds struct dentry * result; 4711da177e4SLinus Torvalds struct inode *dir = parent->d_inode; 4721da177e4SLinus Torvalds 4731b1dcc1bSJes Sorensen mutex_lock(&dir->i_mutex); 4741da177e4SLinus Torvalds /* 4751da177e4SLinus Torvalds * First re-do the cached lookup just in case it was created 4761da177e4SLinus Torvalds * while we waited for the directory semaphore.. 4771da177e4SLinus Torvalds * 4781da177e4SLinus Torvalds * FIXME! This could use version numbering or similar to 4791da177e4SLinus Torvalds * avoid unnecessary cache lookups. 4801da177e4SLinus Torvalds * 4811da177e4SLinus Torvalds * The "dcache_lock" is purely to protect the RCU list walker 4821da177e4SLinus Torvalds * from concurrent renames at this point (we mustn't get false 4831da177e4SLinus Torvalds * negatives from the RCU list walk here, unlike the optimistic 4841da177e4SLinus Torvalds * fast walk). 4851da177e4SLinus Torvalds * 4861da177e4SLinus Torvalds * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 4871da177e4SLinus Torvalds */ 4881da177e4SLinus Torvalds result = d_lookup(parent, name); 4891da177e4SLinus Torvalds if (!result) { 490d70b67c8SMiklos Szeredi struct dentry *dentry; 491d70b67c8SMiklos Szeredi 492d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 493d70b67c8SMiklos Szeredi result = ERR_PTR(-ENOENT); 494d70b67c8SMiklos Szeredi if (IS_DEADDIR(dir)) 495d70b67c8SMiklos Szeredi goto out_unlock; 496d70b67c8SMiklos Szeredi 497d70b67c8SMiklos Szeredi dentry = d_alloc(parent, name); 4981da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 4991da177e4SLinus Torvalds if (dentry) { 5001da177e4SLinus Torvalds result = dir->i_op->lookup(dir, dentry, nd); 5011da177e4SLinus Torvalds if (result) 5021da177e4SLinus Torvalds dput(dentry); 5031da177e4SLinus Torvalds else 5041da177e4SLinus Torvalds result = dentry; 5051da177e4SLinus Torvalds } 506d70b67c8SMiklos Szeredi out_unlock: 5071b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5081da177e4SLinus Torvalds return result; 5091da177e4SLinus Torvalds } 5101da177e4SLinus Torvalds 5111da177e4SLinus Torvalds /* 5121da177e4SLinus Torvalds * Uhhuh! Nasty case: the cache was re-populated while 5131da177e4SLinus Torvalds * we waited on the semaphore. Need to revalidate. 5141da177e4SLinus Torvalds */ 5151b1dcc1bSJes Sorensen mutex_unlock(&dir->i_mutex); 5161da177e4SLinus Torvalds if (result->d_op && result->d_op->d_revalidate) { 517bcdc5e01SIan Kent result = do_revalidate(result, nd); 518bcdc5e01SIan Kent if (!result) 5191da177e4SLinus Torvalds result = ERR_PTR(-ENOENT); 5201da177e4SLinus Torvalds } 5211da177e4SLinus Torvalds return result; 5221da177e4SLinus Torvalds } 5231da177e4SLinus Torvalds 524a02f76c3SAl Viro /* 525a02f76c3SAl Viro * Wrapper to retry pathname resolution whenever the underlying 526a02f76c3SAl Viro * file system returns an ESTALE. 527a02f76c3SAl Viro * 528a02f76c3SAl Viro * Retry the whole path once, forcing real lookup requests 529a02f76c3SAl Viro * instead of relying on the dcache. 530a02f76c3SAl Viro */ 531a02f76c3SAl Viro static __always_inline int link_path_walk(const char *name, struct nameidata *nd) 532a02f76c3SAl Viro { 533a02f76c3SAl Viro struct path save = nd->path; 534a02f76c3SAl Viro int result; 535a02f76c3SAl Viro 536a02f76c3SAl Viro /* make sure the stuff we saved doesn't go away */ 537c8e7f449SJan Blunck path_get(&save); 538a02f76c3SAl Viro 539a02f76c3SAl Viro result = __link_path_walk(name, nd); 540a02f76c3SAl Viro if (result == -ESTALE) { 541a02f76c3SAl Viro /* nd->path had been dropped */ 542a02f76c3SAl Viro nd->path = save; 543c8e7f449SJan Blunck path_get(&nd->path); 544a02f76c3SAl Viro nd->flags |= LOOKUP_REVAL; 545a02f76c3SAl Viro result = __link_path_walk(name, nd); 546a02f76c3SAl Viro } 547a02f76c3SAl Viro 548a02f76c3SAl Viro path_put(&save); 549a02f76c3SAl Viro 550a02f76c3SAl Viro return result; 551a02f76c3SAl Viro } 552a02f76c3SAl Viro 553f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5541da177e4SLinus Torvalds { 5551da177e4SLinus Torvalds int res = 0; 5561da177e4SLinus Torvalds char *name; 5571da177e4SLinus Torvalds if (IS_ERR(link)) 5581da177e4SLinus Torvalds goto fail; 5591da177e4SLinus Torvalds 5601da177e4SLinus Torvalds if (*link == '/') { 561b4091d5fSChristoph Hellwig struct fs_struct *fs = current->fs; 562b4091d5fSChristoph Hellwig 5631d957f9bSJan Blunck path_put(&nd->path); 564b4091d5fSChristoph Hellwig 565b4091d5fSChristoph Hellwig read_lock(&fs->lock); 566b4091d5fSChristoph Hellwig nd->path = fs->root; 567b4091d5fSChristoph Hellwig path_get(&fs->root); 568b4091d5fSChristoph Hellwig read_unlock(&fs->lock); 5691da177e4SLinus Torvalds } 570b4091d5fSChristoph Hellwig 5711da177e4SLinus Torvalds res = link_path_walk(link, nd); 5721da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5731da177e4SLinus Torvalds return res; 5741da177e4SLinus Torvalds /* 5751da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5761da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5771da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5781da177e4SLinus Torvalds */ 5791da177e4SLinus Torvalds name = __getname(); 5801da177e4SLinus Torvalds if (unlikely(!name)) { 5811d957f9bSJan Blunck path_put(&nd->path); 5821da177e4SLinus Torvalds return -ENOMEM; 5831da177e4SLinus Torvalds } 5841da177e4SLinus Torvalds strcpy(name, nd->last.name); 5851da177e4SLinus Torvalds nd->last.name = name; 5861da177e4SLinus Torvalds return 0; 5871da177e4SLinus Torvalds fail: 5881d957f9bSJan Blunck path_put(&nd->path); 5891da177e4SLinus Torvalds return PTR_ERR(link); 5901da177e4SLinus Torvalds } 5911da177e4SLinus Torvalds 5921d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 593051d3812SIan Kent { 594051d3812SIan Kent dput(path->dentry); 5954ac91378SJan Blunck if (path->mnt != nd->path.mnt) 596051d3812SIan Kent mntput(path->mnt); 597051d3812SIan Kent } 598051d3812SIan Kent 599051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 600051d3812SIan Kent { 6014ac91378SJan Blunck dput(nd->path.dentry); 6024ac91378SJan Blunck if (nd->path.mnt != path->mnt) 6034ac91378SJan Blunck mntput(nd->path.mnt); 6044ac91378SJan Blunck nd->path.mnt = path->mnt; 6054ac91378SJan Blunck nd->path.dentry = path->dentry; 606051d3812SIan Kent } 607051d3812SIan Kent 608f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 6091da177e4SLinus Torvalds { 6101da177e4SLinus Torvalds int error; 611cc314eefSLinus Torvalds void *cookie; 612cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 6131da177e4SLinus Torvalds 614d671a1cbSAl Viro touch_atime(path->mnt, dentry); 6151da177e4SLinus Torvalds nd_set_link(nd, NULL); 616cd4e91d3SAl Viro 6174ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 618051d3812SIan Kent path_to_nameidata(path, nd); 619051d3812SIan Kent dget(dentry); 620051d3812SIan Kent } 621cd4e91d3SAl Viro mntget(path->mnt); 622cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 623cc314eefSLinus Torvalds error = PTR_ERR(cookie); 624cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 6251da177e4SLinus Torvalds char *s = nd_get_link(nd); 626cc314eefSLinus Torvalds error = 0; 6271da177e4SLinus Torvalds if (s) 6281da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 6291da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 630cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 6311da177e4SLinus Torvalds } 63209da5916SJan Blunck path_put(path); 6331da177e4SLinus Torvalds 6341da177e4SLinus Torvalds return error; 6351da177e4SLinus Torvalds } 6361da177e4SLinus Torvalds 6371da177e4SLinus Torvalds /* 6381da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 6391da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 6401da177e4SLinus Torvalds * 6411da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 6421da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 6431da177e4SLinus Torvalds */ 64490ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 6451da177e4SLinus Torvalds { 6461da177e4SLinus Torvalds int err = -ELOOP; 6471da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 6481da177e4SLinus Torvalds goto loop; 6491da177e4SLinus Torvalds if (current->total_link_count >= 40) 6501da177e4SLinus Torvalds goto loop; 6511da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 6521da177e4SLinus Torvalds cond_resched(); 65390ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6541da177e4SLinus Torvalds if (err) 6551da177e4SLinus Torvalds goto loop; 6561da177e4SLinus Torvalds current->link_count++; 6571da177e4SLinus Torvalds current->total_link_count++; 6581da177e4SLinus Torvalds nd->depth++; 659cd4e91d3SAl Viro err = __do_follow_link(path, nd); 6601da177e4SLinus Torvalds current->link_count--; 6611da177e4SLinus Torvalds nd->depth--; 6621da177e4SLinus Torvalds return err; 6631da177e4SLinus Torvalds loop: 6641d957f9bSJan Blunck path_put_conditional(path, nd); 6651d957f9bSJan Blunck path_put(&nd->path); 6661da177e4SLinus Torvalds return err; 6671da177e4SLinus Torvalds } 6681da177e4SLinus Torvalds 6691da177e4SLinus Torvalds int follow_up(struct vfsmount **mnt, struct dentry **dentry) 6701da177e4SLinus Torvalds { 6711da177e4SLinus Torvalds struct vfsmount *parent; 6721da177e4SLinus Torvalds struct dentry *mountpoint; 6731da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 6741da177e4SLinus Torvalds parent=(*mnt)->mnt_parent; 6751da177e4SLinus Torvalds if (parent == *mnt) { 6761da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6771da177e4SLinus Torvalds return 0; 6781da177e4SLinus Torvalds } 6791da177e4SLinus Torvalds mntget(parent); 6801da177e4SLinus Torvalds mountpoint=dget((*mnt)->mnt_mountpoint); 6811da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6821da177e4SLinus Torvalds dput(*dentry); 6831da177e4SLinus Torvalds *dentry = mountpoint; 6841da177e4SLinus Torvalds mntput(*mnt); 6851da177e4SLinus Torvalds *mnt = parent; 6861da177e4SLinus Torvalds return 1; 6871da177e4SLinus Torvalds } 6881da177e4SLinus Torvalds 6891da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6901da177e4SLinus Torvalds * namespace.c 6911da177e4SLinus Torvalds */ 692463ffb2eSAl Viro static int __follow_mount(struct path *path) 693463ffb2eSAl Viro { 694463ffb2eSAl Viro int res = 0; 695463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 696463ffb2eSAl Viro struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry); 697463ffb2eSAl Viro if (!mounted) 698463ffb2eSAl Viro break; 699463ffb2eSAl Viro dput(path->dentry); 700463ffb2eSAl Viro if (res) 701463ffb2eSAl Viro mntput(path->mnt); 702463ffb2eSAl Viro path->mnt = mounted; 703463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 704463ffb2eSAl Viro res = 1; 705463ffb2eSAl Viro } 706463ffb2eSAl Viro return res; 707463ffb2eSAl Viro } 708463ffb2eSAl Viro 70958c465ebSAl Viro static void follow_mount(struct vfsmount **mnt, struct dentry **dentry) 7101da177e4SLinus Torvalds { 7111da177e4SLinus Torvalds while (d_mountpoint(*dentry)) { 7121da177e4SLinus Torvalds struct vfsmount *mounted = lookup_mnt(*mnt, *dentry); 7131da177e4SLinus Torvalds if (!mounted) 7141da177e4SLinus Torvalds break; 71558c465ebSAl Viro dput(*dentry); 7161da177e4SLinus Torvalds mntput(*mnt); 7171da177e4SLinus Torvalds *mnt = mounted; 7181da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7191da177e4SLinus Torvalds } 7201da177e4SLinus Torvalds } 7211da177e4SLinus Torvalds 7221da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 7231da177e4SLinus Torvalds * namespace.c 7241da177e4SLinus Torvalds */ 725e13b210fSAl Viro int follow_down(struct vfsmount **mnt, struct dentry **dentry) 7261da177e4SLinus Torvalds { 7271da177e4SLinus Torvalds struct vfsmount *mounted; 7281da177e4SLinus Torvalds 7291da177e4SLinus Torvalds mounted = lookup_mnt(*mnt, *dentry); 7301da177e4SLinus Torvalds if (mounted) { 731e13b210fSAl Viro dput(*dentry); 7321da177e4SLinus Torvalds mntput(*mnt); 7331da177e4SLinus Torvalds *mnt = mounted; 7341da177e4SLinus Torvalds *dentry = dget(mounted->mnt_root); 7351da177e4SLinus Torvalds return 1; 7361da177e4SLinus Torvalds } 7371da177e4SLinus Torvalds return 0; 7381da177e4SLinus Torvalds } 7391da177e4SLinus Torvalds 740f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 7411da177e4SLinus Torvalds { 742e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 743e518ddb7SAndreas Mohr 7441da177e4SLinus Torvalds while(1) { 7451da177e4SLinus Torvalds struct vfsmount *parent; 7464ac91378SJan Blunck struct dentry *old = nd->path.dentry; 7471da177e4SLinus Torvalds 748e518ddb7SAndreas Mohr read_lock(&fs->lock); 7496ac08c39SJan Blunck if (nd->path.dentry == fs->root.dentry && 7506ac08c39SJan Blunck nd->path.mnt == fs->root.mnt) { 751e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7521da177e4SLinus Torvalds break; 7531da177e4SLinus Torvalds } 754e518ddb7SAndreas Mohr read_unlock(&fs->lock); 7551da177e4SLinus Torvalds spin_lock(&dcache_lock); 7564ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7574ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7581da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7591da177e4SLinus Torvalds dput(old); 7601da177e4SLinus Torvalds break; 7611da177e4SLinus Torvalds } 7621da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7631da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7644ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7654ac91378SJan Blunck if (parent == nd->path.mnt) { 7661da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7671da177e4SLinus Torvalds break; 7681da177e4SLinus Torvalds } 7691da177e4SLinus Torvalds mntget(parent); 7704ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7711da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7721da177e4SLinus Torvalds dput(old); 7734ac91378SJan Blunck mntput(nd->path.mnt); 7744ac91378SJan Blunck nd->path.mnt = parent; 7751da177e4SLinus Torvalds } 7764ac91378SJan Blunck follow_mount(&nd->path.mnt, &nd->path.dentry); 7771da177e4SLinus Torvalds } 7781da177e4SLinus Torvalds 7791da177e4SLinus Torvalds /* 7801da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7811da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7821da177e4SLinus Torvalds * It _is_ time-critical. 7831da177e4SLinus Torvalds */ 7841da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7851da177e4SLinus Torvalds struct path *path) 7861da177e4SLinus Torvalds { 7874ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 7884ac91378SJan Blunck struct dentry *dentry = __d_lookup(nd->path.dentry, name); 7891da177e4SLinus Torvalds 7901da177e4SLinus Torvalds if (!dentry) 7911da177e4SLinus Torvalds goto need_lookup; 7921da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 7931da177e4SLinus Torvalds goto need_revalidate; 7941da177e4SLinus Torvalds done: 7951da177e4SLinus Torvalds path->mnt = mnt; 7961da177e4SLinus Torvalds path->dentry = dentry; 797634ee701SAl Viro __follow_mount(path); 7981da177e4SLinus Torvalds return 0; 7991da177e4SLinus Torvalds 8001da177e4SLinus Torvalds need_lookup: 8014ac91378SJan Blunck dentry = real_lookup(nd->path.dentry, name, nd); 8021da177e4SLinus Torvalds if (IS_ERR(dentry)) 8031da177e4SLinus Torvalds goto fail; 8041da177e4SLinus Torvalds goto done; 8051da177e4SLinus Torvalds 8061da177e4SLinus Torvalds need_revalidate: 807bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 808bcdc5e01SIan Kent if (!dentry) 8091da177e4SLinus Torvalds goto need_lookup; 810bcdc5e01SIan Kent if (IS_ERR(dentry)) 811bcdc5e01SIan Kent goto fail; 812bcdc5e01SIan Kent goto done; 8131da177e4SLinus Torvalds 8141da177e4SLinus Torvalds fail: 8151da177e4SLinus Torvalds return PTR_ERR(dentry); 8161da177e4SLinus Torvalds } 8171da177e4SLinus Torvalds 8181da177e4SLinus Torvalds /* 8191da177e4SLinus Torvalds * Name resolution. 820ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 821ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8221da177e4SLinus Torvalds * 823ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 824ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8251da177e4SLinus Torvalds */ 826fc9b52cdSHarvey Harrison static int __link_path_walk(const char *name, struct nameidata *nd) 8271da177e4SLinus Torvalds { 8281da177e4SLinus Torvalds struct path next; 8291da177e4SLinus Torvalds struct inode *inode; 8301da177e4SLinus Torvalds int err; 8311da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8321da177e4SLinus Torvalds 8331da177e4SLinus Torvalds while (*name=='/') 8341da177e4SLinus Torvalds name++; 8351da177e4SLinus Torvalds if (!*name) 8361da177e4SLinus Torvalds goto return_reval; 8371da177e4SLinus Torvalds 8384ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8391da177e4SLinus Torvalds if (nd->depth) 840f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8411da177e4SLinus Torvalds 8421da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8431da177e4SLinus Torvalds for(;;) { 8441da177e4SLinus Torvalds unsigned long hash; 8451da177e4SLinus Torvalds struct qstr this; 8461da177e4SLinus Torvalds unsigned int c; 8471da177e4SLinus Torvalds 848cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 849672b16b2SAl Viro err = exec_permission_lite(inode); 850e4543eddSChristoph Hellwig if (err == -EAGAIN) 851cb23beb5SChristoph Hellwig err = inode_permission(nd->path.dentry->d_inode, 852cb23beb5SChristoph Hellwig MAY_EXEC); 8531da177e4SLinus Torvalds if (err) 8541da177e4SLinus Torvalds break; 8551da177e4SLinus Torvalds 8561da177e4SLinus Torvalds this.name = name; 8571da177e4SLinus Torvalds c = *(const unsigned char *)name; 8581da177e4SLinus Torvalds 8591da177e4SLinus Torvalds hash = init_name_hash(); 8601da177e4SLinus Torvalds do { 8611da177e4SLinus Torvalds name++; 8621da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8631da177e4SLinus Torvalds c = *(const unsigned char *)name; 8641da177e4SLinus Torvalds } while (c && (c != '/')); 8651da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8661da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8671da177e4SLinus Torvalds 8681da177e4SLinus Torvalds /* remove trailing slashes? */ 8691da177e4SLinus Torvalds if (!c) 8701da177e4SLinus Torvalds goto last_component; 8711da177e4SLinus Torvalds while (*++name == '/'); 8721da177e4SLinus Torvalds if (!*name) 8731da177e4SLinus Torvalds goto last_with_slashes; 8741da177e4SLinus Torvalds 8751da177e4SLinus Torvalds /* 8761da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8771da177e4SLinus Torvalds * to be able to know about the current root directory and 8781da177e4SLinus Torvalds * parent relationships. 8791da177e4SLinus Torvalds */ 8801da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8811da177e4SLinus Torvalds default: 8821da177e4SLinus Torvalds break; 8831da177e4SLinus Torvalds case 2: 8841da177e4SLinus Torvalds if (this.name[1] != '.') 8851da177e4SLinus Torvalds break; 88658c465ebSAl Viro follow_dotdot(nd); 8874ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8881da177e4SLinus Torvalds /* fallthrough */ 8891da177e4SLinus Torvalds case 1: 8901da177e4SLinus Torvalds continue; 8911da177e4SLinus Torvalds } 8921da177e4SLinus Torvalds /* 8931da177e4SLinus Torvalds * See if the low-level filesystem might want 8941da177e4SLinus Torvalds * to use its own hash.. 8951da177e4SLinus Torvalds */ 8964ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 8974ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 8984ac91378SJan Blunck &this); 8991da177e4SLinus Torvalds if (err < 0) 9001da177e4SLinus Torvalds break; 9011da177e4SLinus Torvalds } 9021da177e4SLinus Torvalds /* This does the actual lookups.. */ 9031da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9041da177e4SLinus Torvalds if (err) 9051da177e4SLinus Torvalds break; 9061da177e4SLinus Torvalds 9071da177e4SLinus Torvalds err = -ENOENT; 9081da177e4SLinus Torvalds inode = next.dentry->d_inode; 9091da177e4SLinus Torvalds if (!inode) 9101da177e4SLinus Torvalds goto out_dput; 9111da177e4SLinus Torvalds err = -ENOTDIR; 9121da177e4SLinus Torvalds if (!inode->i_op) 9131da177e4SLinus Torvalds goto out_dput; 9141da177e4SLinus Torvalds 9151da177e4SLinus Torvalds if (inode->i_op->follow_link) { 91690ebe565SAl Viro err = do_follow_link(&next, nd); 9171da177e4SLinus Torvalds if (err) 9181da177e4SLinus Torvalds goto return_err; 9191da177e4SLinus Torvalds err = -ENOENT; 9204ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9211da177e4SLinus Torvalds if (!inode) 9221da177e4SLinus Torvalds break; 9231da177e4SLinus Torvalds err = -ENOTDIR; 9241da177e4SLinus Torvalds if (!inode->i_op) 9251da177e4SLinus Torvalds break; 92609dd17d3SMiklos Szeredi } else 92709dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9281da177e4SLinus Torvalds err = -ENOTDIR; 9291da177e4SLinus Torvalds if (!inode->i_op->lookup) 9301da177e4SLinus Torvalds break; 9311da177e4SLinus Torvalds continue; 9321da177e4SLinus Torvalds /* here ends the main loop */ 9331da177e4SLinus Torvalds 9341da177e4SLinus Torvalds last_with_slashes: 9351da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9361da177e4SLinus Torvalds last_component: 937f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 938f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9391da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9401da177e4SLinus Torvalds goto lookup_parent; 9411da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9421da177e4SLinus Torvalds default: 9431da177e4SLinus Torvalds break; 9441da177e4SLinus Torvalds case 2: 9451da177e4SLinus Torvalds if (this.name[1] != '.') 9461da177e4SLinus Torvalds break; 94758c465ebSAl Viro follow_dotdot(nd); 9484ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9491da177e4SLinus Torvalds /* fallthrough */ 9501da177e4SLinus Torvalds case 1: 9511da177e4SLinus Torvalds goto return_reval; 9521da177e4SLinus Torvalds } 9534ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9544ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9554ac91378SJan Blunck &this); 9561da177e4SLinus Torvalds if (err < 0) 9571da177e4SLinus Torvalds break; 9581da177e4SLinus Torvalds } 9591da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9601da177e4SLinus Torvalds if (err) 9611da177e4SLinus Torvalds break; 9621da177e4SLinus Torvalds inode = next.dentry->d_inode; 9631da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 9641da177e4SLinus Torvalds && inode && inode->i_op && inode->i_op->follow_link) { 96590ebe565SAl Viro err = do_follow_link(&next, nd); 9661da177e4SLinus Torvalds if (err) 9671da177e4SLinus Torvalds goto return_err; 9684ac91378SJan Blunck inode = nd->path.dentry->d_inode; 96909dd17d3SMiklos Szeredi } else 97009dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9711da177e4SLinus Torvalds err = -ENOENT; 9721da177e4SLinus Torvalds if (!inode) 9731da177e4SLinus Torvalds break; 9741da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9751da177e4SLinus Torvalds err = -ENOTDIR; 9761da177e4SLinus Torvalds if (!inode->i_op || !inode->i_op->lookup) 9771da177e4SLinus Torvalds break; 9781da177e4SLinus Torvalds } 9791da177e4SLinus Torvalds goto return_base; 9801da177e4SLinus Torvalds lookup_parent: 9811da177e4SLinus Torvalds nd->last = this; 9821da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9831da177e4SLinus Torvalds if (this.name[0] != '.') 9841da177e4SLinus Torvalds goto return_base; 9851da177e4SLinus Torvalds if (this.len == 1) 9861da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9871da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9881da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9891da177e4SLinus Torvalds else 9901da177e4SLinus Torvalds goto return_base; 9911da177e4SLinus Torvalds return_reval: 9921da177e4SLinus Torvalds /* 9931da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 9941da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 9951da177e4SLinus Torvalds */ 9964ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 9974ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 9981da177e4SLinus Torvalds err = -ESTALE; 9991da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 10004ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 10014ac91378SJan Blunck nd->path.dentry, nd)) 10021da177e4SLinus Torvalds break; 10031da177e4SLinus Torvalds } 10041da177e4SLinus Torvalds return_base: 10051da177e4SLinus Torvalds return 0; 10061da177e4SLinus Torvalds out_dput: 10071d957f9bSJan Blunck path_put_conditional(&next, nd); 10081da177e4SLinus Torvalds break; 10091da177e4SLinus Torvalds } 10101d957f9bSJan Blunck path_put(&nd->path); 10111da177e4SLinus Torvalds return_err: 10121da177e4SLinus Torvalds return err; 10131da177e4SLinus Torvalds } 10141da177e4SLinus Torvalds 1015fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10161da177e4SLinus Torvalds { 10171da177e4SLinus Torvalds current->total_link_count = 0; 10181da177e4SLinus Torvalds return link_path_walk(name, nd); 10191da177e4SLinus Torvalds } 10201da177e4SLinus Torvalds 1021ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1022fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 10235590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 10241da177e4SLinus Torvalds { 1025ea3834d9SPrasanna Meda int retval = 0; 1026170aa3d0SUlrich Drepper int fput_needed; 1027170aa3d0SUlrich Drepper struct file *file; 1028e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 10291da177e4SLinus Torvalds 10301da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10311da177e4SLinus Torvalds nd->flags = flags; 10321da177e4SLinus Torvalds nd->depth = 0; 10331da177e4SLinus Torvalds 10341da177e4SLinus Torvalds if (*name=='/') { 1035e518ddb7SAndreas Mohr read_lock(&fs->lock); 10366ac08c39SJan Blunck nd->path = fs->root; 10376ac08c39SJan Blunck path_get(&fs->root); 1038e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10395590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1040e518ddb7SAndreas Mohr read_lock(&fs->lock); 10416ac08c39SJan Blunck nd->path = fs->pwd; 10426ac08c39SJan Blunck path_get(&fs->pwd); 1043e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10445590ff0dSUlrich Drepper } else { 10455590ff0dSUlrich Drepper struct dentry *dentry; 10465590ff0dSUlrich Drepper 10475590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10485590ff0dSUlrich Drepper retval = -EBADF; 1049170aa3d0SUlrich Drepper if (!file) 10506d09bb62STrond Myklebust goto out_fail; 10515590ff0dSUlrich Drepper 10520f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10535590ff0dSUlrich Drepper 10545590ff0dSUlrich Drepper retval = -ENOTDIR; 1055170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10566d09bb62STrond Myklebust goto fput_fail; 10575590ff0dSUlrich Drepper 10585590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1059170aa3d0SUlrich Drepper if (retval) 10606d09bb62STrond Myklebust goto fput_fail; 10615590ff0dSUlrich Drepper 10625dd784d0SJan Blunck nd->path = file->f_path; 10635dd784d0SJan Blunck path_get(&file->f_path); 10645590ff0dSUlrich Drepper 10655590ff0dSUlrich Drepper fput_light(file, fput_needed); 10661da177e4SLinus Torvalds } 10672dfdd266SJosef 'Jeff' Sipek 10682dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10694ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10704ac91378SJan Blunck nd->path.dentry->d_inode)) 10714ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10726d09bb62STrond Myklebust out_fail: 1073170aa3d0SUlrich Drepper return retval; 1074170aa3d0SUlrich Drepper 10756d09bb62STrond Myklebust fput_fail: 1076170aa3d0SUlrich Drepper fput_light(file, fput_needed); 10776d09bb62STrond Myklebust goto out_fail; 10781da177e4SLinus Torvalds } 10791da177e4SLinus Torvalds 1080fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 10815590ff0dSUlrich Drepper struct nameidata *nd) 10825590ff0dSUlrich Drepper { 10835590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 10845590ff0dSUlrich Drepper } 10855590ff0dSUlrich Drepper 1086d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1087d1811465SAl Viro { 1088d1811465SAl Viro struct nameidata nd; 1089d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1090d1811465SAl Viro if (!res) 1091d1811465SAl Viro *path = nd.path; 1092d1811465SAl Viro return res; 1093d1811465SAl Viro } 1094d1811465SAl Viro 109516f18200SJosef 'Jeff' Sipek /** 109616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 109716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 109816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 109916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 110016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 110116f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 110216f18200SJosef 'Jeff' Sipek */ 110316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 110416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 110516f18200SJosef 'Jeff' Sipek struct nameidata *nd) 110616f18200SJosef 'Jeff' Sipek { 110716f18200SJosef 'Jeff' Sipek int retval; 110816f18200SJosef 'Jeff' Sipek 110916f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 111016f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 111116f18200SJosef 'Jeff' Sipek nd->flags = flags; 111216f18200SJosef 'Jeff' Sipek nd->depth = 0; 111316f18200SJosef 'Jeff' Sipek 1114c8e7f449SJan Blunck nd->path.dentry = dentry; 1115c8e7f449SJan Blunck nd->path.mnt = mnt; 1116c8e7f449SJan Blunck path_get(&nd->path); 111716f18200SJosef 'Jeff' Sipek 111816f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11194ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11204ac91378SJan Blunck nd->path.dentry->d_inode)) 11214ac91378SJan Blunck audit_inode(name, nd->path.dentry); 112216f18200SJosef 'Jeff' Sipek 112316f18200SJosef 'Jeff' Sipek return retval; 112416f18200SJosef 'Jeff' Sipek 112516f18200SJosef 'Jeff' Sipek } 112616f18200SJosef 'Jeff' Sipek 1127834f2a4aSTrond Myklebust /** 1128834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 11297045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1130834f2a4aSTrond Myklebust * @name: pointer to file name 1131834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1132834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1133834f2a4aSTrond Myklebust * @open_flags: open intent flags 1134834f2a4aSTrond Myklebust */ 11355590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1136834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1137834f2a4aSTrond Myklebust { 11388737f3a1SAl Viro struct file *filp = get_empty_filp(); 11398737f3a1SAl Viro int err; 1140834f2a4aSTrond Myklebust 11418737f3a1SAl Viro if (filp == NULL) 11428737f3a1SAl Viro return -ENFILE; 11438737f3a1SAl Viro nd->intent.open.file = filp; 11448737f3a1SAl Viro nd->intent.open.flags = open_flags; 11458737f3a1SAl Viro nd->intent.open.create_mode = 0; 11468737f3a1SAl Viro err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 11478737f3a1SAl Viro if (IS_ERR(nd->intent.open.file)) { 11488737f3a1SAl Viro if (err == 0) { 11498737f3a1SAl Viro err = PTR_ERR(nd->intent.open.file); 11508737f3a1SAl Viro path_put(&nd->path); 11518737f3a1SAl Viro } 11528737f3a1SAl Viro } else if (err != 0) 11538737f3a1SAl Viro release_open_intent(nd); 11548737f3a1SAl Viro return err; 1155834f2a4aSTrond Myklebust } 1156834f2a4aSTrond Myklebust 1157eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1158eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 11591da177e4SLinus Torvalds { 11601da177e4SLinus Torvalds struct dentry *dentry; 11611da177e4SLinus Torvalds struct inode *inode; 11621da177e4SLinus Torvalds int err; 11631da177e4SLinus Torvalds 11641da177e4SLinus Torvalds inode = base->d_inode; 11651da177e4SLinus Torvalds 11661da177e4SLinus Torvalds /* 11671da177e4SLinus Torvalds * See if the low-level filesystem might want 11681da177e4SLinus Torvalds * to use its own hash.. 11691da177e4SLinus Torvalds */ 11701da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 11711da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 11721da177e4SLinus Torvalds dentry = ERR_PTR(err); 11731da177e4SLinus Torvalds if (err < 0) 11741da177e4SLinus Torvalds goto out; 11751da177e4SLinus Torvalds } 11761da177e4SLinus Torvalds 11771da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 11781da177e4SLinus Torvalds if (!dentry) { 1179d70b67c8SMiklos Szeredi struct dentry *new; 1180d70b67c8SMiklos Szeredi 1181d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1182d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1183d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1184d70b67c8SMiklos Szeredi goto out; 1185d70b67c8SMiklos Szeredi 1186d70b67c8SMiklos Szeredi new = d_alloc(base, name); 11871da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 11881da177e4SLinus Torvalds if (!new) 11891da177e4SLinus Torvalds goto out; 11901da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 11911da177e4SLinus Torvalds if (!dentry) 11921da177e4SLinus Torvalds dentry = new; 11931da177e4SLinus Torvalds else 11941da177e4SLinus Torvalds dput(new); 11951da177e4SLinus Torvalds } 11961da177e4SLinus Torvalds out: 11971da177e4SLinus Torvalds return dentry; 11981da177e4SLinus Torvalds } 11991da177e4SLinus Torvalds 1200057f6c01SJames Morris /* 1201057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1202057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1203057f6c01SJames Morris * SMP-safe. 1204057f6c01SJames Morris */ 1205a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 12061da177e4SLinus Torvalds { 1207eead1911SChristoph Hellwig int err; 1208eead1911SChristoph Hellwig 1209f419a2e3SAl Viro err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC); 1210eead1911SChristoph Hellwig if (err) 1211eead1911SChristoph Hellwig return ERR_PTR(err); 12124ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 12131da177e4SLinus Torvalds } 12141da177e4SLinus Torvalds 1215eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1216eead1911SChristoph Hellwig struct dentry *base, int len) 12171da177e4SLinus Torvalds { 12181da177e4SLinus Torvalds unsigned long hash; 12191da177e4SLinus Torvalds unsigned int c; 12201da177e4SLinus Torvalds 1221057f6c01SJames Morris this->name = name; 1222057f6c01SJames Morris this->len = len; 12231da177e4SLinus Torvalds if (!len) 1224057f6c01SJames Morris return -EACCES; 12251da177e4SLinus Torvalds 12261da177e4SLinus Torvalds hash = init_name_hash(); 12271da177e4SLinus Torvalds while (len--) { 12281da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12291da177e4SLinus Torvalds if (c == '/' || c == '\0') 1230057f6c01SJames Morris return -EACCES; 12311da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12321da177e4SLinus Torvalds } 1233057f6c01SJames Morris this->hash = end_name_hash(hash); 1234057f6c01SJames Morris return 0; 1235057f6c01SJames Morris } 12361da177e4SLinus Torvalds 1237eead1911SChristoph Hellwig /** 1238a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1239eead1911SChristoph Hellwig * @name: pathname component to lookup 1240eead1911SChristoph Hellwig * @base: base directory to lookup from 1241eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1242eead1911SChristoph Hellwig * 1243a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1244a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1245eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1246eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1247eead1911SChristoph Hellwig */ 1248057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1249057f6c01SJames Morris { 1250057f6c01SJames Morris int err; 1251057f6c01SJames Morris struct qstr this; 1252057f6c01SJames Morris 1253057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1254057f6c01SJames Morris if (err) 1255057f6c01SJames Morris return ERR_PTR(err); 1256eead1911SChristoph Hellwig 1257f419a2e3SAl Viro err = inode_permission(base->d_inode, MAY_EXEC); 1258eead1911SChristoph Hellwig if (err) 1259eead1911SChristoph Hellwig return ERR_PTR(err); 126049705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1261057f6c01SJames Morris } 1262057f6c01SJames Morris 1263eead1911SChristoph Hellwig /** 1264eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1265eead1911SChristoph Hellwig * @name: pathname component to lookup 1266eead1911SChristoph Hellwig * @base: base directory to lookup from 1267eead1911SChristoph Hellwig * 1268eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1269eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1270eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1271eead1911SChristoph Hellwig * 1272eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1273eead1911SChristoph Hellwig */ 1274eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1275057f6c01SJames Morris { 1276057f6c01SJames Morris int err; 1277057f6c01SJames Morris struct qstr this; 1278057f6c01SJames Morris 1279eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1280057f6c01SJames Morris if (err) 1281057f6c01SJames Morris return ERR_PTR(err); 1282eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 12831da177e4SLinus Torvalds } 12841da177e4SLinus Torvalds 12852d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 12862d8f3038SAl Viro struct path *path) 12871da177e4SLinus Torvalds { 12882d8f3038SAl Viro struct nameidata nd; 12891da177e4SLinus Torvalds char *tmp = getname(name); 12901da177e4SLinus Torvalds int err = PTR_ERR(tmp); 12911da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 12922d8f3038SAl Viro 12932d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 12942d8f3038SAl Viro 12952d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 12961da177e4SLinus Torvalds putname(tmp); 12972d8f3038SAl Viro if (!err) 12982d8f3038SAl Viro *path = nd.path; 12991da177e4SLinus Torvalds } 13001da177e4SLinus Torvalds return err; 13011da177e4SLinus Torvalds } 13021da177e4SLinus Torvalds 13032ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 13042ad94ae6SAl Viro struct nameidata *nd, char **name) 13052ad94ae6SAl Viro { 13062ad94ae6SAl Viro char *s = getname(path); 13072ad94ae6SAl Viro int error; 13082ad94ae6SAl Viro 13092ad94ae6SAl Viro if (IS_ERR(s)) 13102ad94ae6SAl Viro return PTR_ERR(s); 13112ad94ae6SAl Viro 13122ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 13132ad94ae6SAl Viro if (error) 13142ad94ae6SAl Viro putname(s); 13152ad94ae6SAl Viro else 13162ad94ae6SAl Viro *name = s; 13172ad94ae6SAl Viro 13182ad94ae6SAl Viro return error; 13192ad94ae6SAl Viro } 13202ad94ae6SAl Viro 13211da177e4SLinus Torvalds /* 13221da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 13231da177e4SLinus Torvalds * minimal. 13241da177e4SLinus Torvalds */ 13251da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 13261da177e4SLinus Torvalds { 1327da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1328da9592edSDavid Howells 13291da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 13301da177e4SLinus Torvalds return 0; 1331da9592edSDavid Howells if (inode->i_uid == fsuid) 13321da177e4SLinus Torvalds return 0; 1333da9592edSDavid Howells if (dir->i_uid == fsuid) 13341da177e4SLinus Torvalds return 0; 13351da177e4SLinus Torvalds return !capable(CAP_FOWNER); 13361da177e4SLinus Torvalds } 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds /* 13391da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 13401da177e4SLinus Torvalds * whether the type of victim is right. 13411da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 13421da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 13431da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 13441da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13451da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13461da177e4SLinus Torvalds * a. be owner of dir, or 13471da177e4SLinus Torvalds * b. be owner of victim, or 13481da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13491da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 13501da177e4SLinus Torvalds * links pointing to it. 13511da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 13521da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 13531da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 13541da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 13551da177e4SLinus Torvalds * nfs_async_unlink(). 13561da177e4SLinus Torvalds */ 1357858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 13581da177e4SLinus Torvalds { 13591da177e4SLinus Torvalds int error; 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds if (!victim->d_inode) 13621da177e4SLinus Torvalds return -ENOENT; 13631da177e4SLinus Torvalds 13641da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 13655a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 13661da177e4SLinus Torvalds 1367f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 13681da177e4SLinus Torvalds if (error) 13691da177e4SLinus Torvalds return error; 13701da177e4SLinus Torvalds if (IS_APPEND(dir)) 13711da177e4SLinus Torvalds return -EPERM; 13721da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1373f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 13741da177e4SLinus Torvalds return -EPERM; 13751da177e4SLinus Torvalds if (isdir) { 13761da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 13771da177e4SLinus Torvalds return -ENOTDIR; 13781da177e4SLinus Torvalds if (IS_ROOT(victim)) 13791da177e4SLinus Torvalds return -EBUSY; 13801da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 13811da177e4SLinus Torvalds return -EISDIR; 13821da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13831da177e4SLinus Torvalds return -ENOENT; 13841da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 13851da177e4SLinus Torvalds return -EBUSY; 13861da177e4SLinus Torvalds return 0; 13871da177e4SLinus Torvalds } 13881da177e4SLinus Torvalds 13891da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 13901da177e4SLinus Torvalds * dir. 13911da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 13921da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 13931da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 13941da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 13951da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 13961da177e4SLinus Torvalds */ 1397a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 13981da177e4SLinus Torvalds { 13991da177e4SLinus Torvalds if (child->d_inode) 14001da177e4SLinus Torvalds return -EEXIST; 14011da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 14021da177e4SLinus Torvalds return -ENOENT; 1403f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 14041da177e4SLinus Torvalds } 14051da177e4SLinus Torvalds 14061da177e4SLinus Torvalds /* 14071da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 14081da177e4SLinus Torvalds */ 14091da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 14101da177e4SLinus Torvalds { 14111da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 14121da177e4SLinus Torvalds 14131da177e4SLinus Torvalds if (f & O_NOFOLLOW) 14141da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 14151da177e4SLinus Torvalds 14161da177e4SLinus Torvalds if (f & O_DIRECTORY) 14171da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 14181da177e4SLinus Torvalds 14191da177e4SLinus Torvalds return retval; 14201da177e4SLinus Torvalds } 14211da177e4SLinus Torvalds 14221da177e4SLinus Torvalds /* 14231da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 14241da177e4SLinus Torvalds */ 14251da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 14261da177e4SLinus Torvalds { 14271da177e4SLinus Torvalds struct dentry *p; 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds if (p1 == p2) { 1430f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 14311da177e4SLinus Torvalds return NULL; 14321da177e4SLinus Torvalds } 14331da177e4SLinus Torvalds 1434a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14351da177e4SLinus Torvalds 1436e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1437e2761a11SOGAWA Hirofumi if (p) { 1438f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1439f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 14401da177e4SLinus Torvalds return p; 14411da177e4SLinus Torvalds } 14421da177e4SLinus Torvalds 1443e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1444e2761a11SOGAWA Hirofumi if (p) { 1445f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1446f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14471da177e4SLinus Torvalds return p; 14481da177e4SLinus Torvalds } 14491da177e4SLinus Torvalds 1450f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1451f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14521da177e4SLinus Torvalds return NULL; 14531da177e4SLinus Torvalds } 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 14561da177e4SLinus Torvalds { 14571b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 14581da177e4SLinus Torvalds if (p1 != p2) { 14591b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1460a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14611da177e4SLinus Torvalds } 14621da177e4SLinus Torvalds } 14631da177e4SLinus Torvalds 14641da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 14651da177e4SLinus Torvalds struct nameidata *nd) 14661da177e4SLinus Torvalds { 1467a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 14681da177e4SLinus Torvalds 14691da177e4SLinus Torvalds if (error) 14701da177e4SLinus Torvalds return error; 14711da177e4SLinus Torvalds 14721da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->create) 14731da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 14741da177e4SLinus Torvalds mode &= S_IALLUGO; 14751da177e4SLinus Torvalds mode |= S_IFREG; 14761da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 14771da177e4SLinus Torvalds if (error) 14781da177e4SLinus Torvalds return error; 14791da177e4SLinus Torvalds DQUOT_INIT(dir); 14801da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1481a74574aaSStephen Smalley if (!error) 1482f38aa942SAmy Griffis fsnotify_create(dir, dentry); 14831da177e4SLinus Torvalds return error; 14841da177e4SLinus Torvalds } 14851da177e4SLinus Torvalds 14863fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 14871da177e4SLinus Torvalds { 14883fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 14891da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 14901da177e4SLinus Torvalds int error; 14911da177e4SLinus Torvalds 14921da177e4SLinus Torvalds if (!inode) 14931da177e4SLinus Torvalds return -ENOENT; 14941da177e4SLinus Torvalds 14951da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 14961da177e4SLinus Torvalds return -ELOOP; 14971da177e4SLinus Torvalds 1498974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 14991da177e4SLinus Torvalds return -EISDIR; 15001da177e4SLinus Torvalds 15011da177e4SLinus Torvalds /* 15021da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 15031da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 15041da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 15051da177e4SLinus Torvalds */ 15061da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 15071da177e4SLinus Torvalds flag &= ~O_TRUNC; 15081da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 15093fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 15101da177e4SLinus Torvalds return -EACCES; 15111da177e4SLinus Torvalds 15121da177e4SLinus Torvalds flag &= ~O_TRUNC; 15134a3fd211SDave Hansen } 1514b41572e9SDave Hansen 15153fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1516b41572e9SDave Hansen if (error) 1517b41572e9SDave Hansen return error; 15181da177e4SLinus Torvalds /* 15191da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 15201da177e4SLinus Torvalds */ 15211da177e4SLinus Torvalds if (IS_APPEND(inode)) { 15221da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 15231da177e4SLinus Torvalds return -EPERM; 15241da177e4SLinus Torvalds if (flag & O_TRUNC) 15251da177e4SLinus Torvalds return -EPERM; 15261da177e4SLinus Torvalds } 15271da177e4SLinus Torvalds 15281da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15291da177e4SLinus Torvalds if (flag & O_NOATIME) 15303bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 15311da177e4SLinus Torvalds return -EPERM; 15321da177e4SLinus Torvalds 15331da177e4SLinus Torvalds /* 15341da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15351da177e4SLinus Torvalds */ 15361da177e4SLinus Torvalds error = break_lease(inode, flag); 15371da177e4SLinus Torvalds if (error) 15381da177e4SLinus Torvalds return error; 15391da177e4SLinus Torvalds 15401da177e4SLinus Torvalds if (flag & O_TRUNC) { 15411da177e4SLinus Torvalds error = get_write_access(inode); 15421da177e4SLinus Torvalds if (error) 15431da177e4SLinus Torvalds return error; 15441da177e4SLinus Torvalds 15451da177e4SLinus Torvalds /* 15461da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 15471da177e4SLinus Torvalds */ 15481da177e4SLinus Torvalds error = locks_verify_locked(inode); 1549be6d3e56SKentaro Takeda if (!error) 15503fb64190SChristoph Hellwig error = security_path_truncate(path, 0, 1551be6d3e56SKentaro Takeda ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); 15521da177e4SLinus Torvalds if (!error) { 15531da177e4SLinus Torvalds DQUOT_INIT(inode); 15541da177e4SLinus Torvalds 1555d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1556d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1557d139d7ffSMiklos Szeredi NULL); 15581da177e4SLinus Torvalds } 15591da177e4SLinus Torvalds put_write_access(inode); 15601da177e4SLinus Torvalds if (error) 15611da177e4SLinus Torvalds return error; 15621da177e4SLinus Torvalds } else 15631da177e4SLinus Torvalds if (flag & FMODE_WRITE) 15641da177e4SLinus Torvalds DQUOT_INIT(inode); 15651da177e4SLinus Torvalds 15661da177e4SLinus Torvalds return 0; 15671da177e4SLinus Torvalds } 15681da177e4SLinus Torvalds 1569d57999e1SDave Hansen /* 1570d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1571d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1572d57999e1SDave Hansen * what get passed to sys_open(). 1573d57999e1SDave Hansen */ 1574d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1575aab520e2SDave Hansen int flag, int mode) 1576aab520e2SDave Hansen { 1577aab520e2SDave Hansen int error; 15784ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1579aab520e2SDave Hansen 1580aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1581aab520e2SDave Hansen mode &= ~current->fs->umask; 1582be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1583be6d3e56SKentaro Takeda if (error) 1584be6d3e56SKentaro Takeda goto out_unlock; 1585aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1586be6d3e56SKentaro Takeda out_unlock: 1587aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 15884ac91378SJan Blunck dput(nd->path.dentry); 15894ac91378SJan Blunck nd->path.dentry = path->dentry; 1590aab520e2SDave Hansen if (error) 1591aab520e2SDave Hansen return error; 1592aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 15933fb64190SChristoph Hellwig return may_open(&nd->path, 0, flag & ~O_TRUNC); 1594aab520e2SDave Hansen } 1595aab520e2SDave Hansen 15961da177e4SLinus Torvalds /* 1597d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1598d57999e1SDave Hansen * 00 - read-only 1599d57999e1SDave Hansen * 01 - write-only 1600d57999e1SDave Hansen * 10 - read-write 1601d57999e1SDave Hansen * 11 - special 1602d57999e1SDave Hansen * it is changed into 1603d57999e1SDave Hansen * 00 - no permissions needed 1604d57999e1SDave Hansen * 01 - read-permission 1605d57999e1SDave Hansen * 10 - write-permission 1606d57999e1SDave Hansen * 11 - read-write 1607d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1608d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1609d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1610d57999e1SDave Hansen * later). 1611d57999e1SDave Hansen * 1612d57999e1SDave Hansen */ 1613d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1614d57999e1SDave Hansen { 1615d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1616d57999e1SDave Hansen flag++; 1617d57999e1SDave Hansen return flag; 1618d57999e1SDave Hansen } 1619d57999e1SDave Hansen 16204a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 16214a3fd211SDave Hansen { 1622d57999e1SDave Hansen /* 16234a3fd211SDave Hansen * We'll never write to the fs underlying 16244a3fd211SDave Hansen * a device file. 16254a3fd211SDave Hansen */ 16264a3fd211SDave Hansen if (special_file(inode->i_mode)) 16274a3fd211SDave Hansen return 0; 16284a3fd211SDave Hansen return (flag & O_TRUNC); 16294a3fd211SDave Hansen } 16304a3fd211SDave Hansen 16314a3fd211SDave Hansen /* 16324a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16334a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16344a3fd211SDave Hansen * open_to_namei_flags() for more details. 16351da177e4SLinus Torvalds */ 1636a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 1637a70e65dfSChristoph Hellwig int open_flag, int mode) 16381da177e4SLinus Torvalds { 16394a3fd211SDave Hansen struct file *filp; 1640a70e65dfSChristoph Hellwig struct nameidata nd; 1641834f2a4aSTrond Myklebust int acc_mode, error; 16424e7506e4SAl Viro struct path path; 16431da177e4SLinus Torvalds struct dentry *dir; 16441da177e4SLinus Torvalds int count = 0; 16454a3fd211SDave Hansen int will_write; 1646d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16471da177e4SLinus Torvalds 1648b77b0646SAl Viro acc_mode = MAY_OPEN | ACC_MODE(flag); 16491da177e4SLinus Torvalds 1650834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1651834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1652834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1653834f2a4aSTrond Myklebust 16541da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 16551da177e4SLinus Torvalds access from general write access. */ 16561da177e4SLinus Torvalds if (flag & O_APPEND) 16571da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 16581da177e4SLinus Torvalds 16591da177e4SLinus Torvalds /* 16601da177e4SLinus Torvalds * The simplest case - just a plain lookup. 16611da177e4SLinus Torvalds */ 16621da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 16635590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1664a70e65dfSChristoph Hellwig &nd, flag); 16651da177e4SLinus Torvalds if (error) 1666a70e65dfSChristoph Hellwig return ERR_PTR(error); 16671da177e4SLinus Torvalds goto ok; 16681da177e4SLinus Torvalds } 16691da177e4SLinus Torvalds 16701da177e4SLinus Torvalds /* 16711da177e4SLinus Torvalds * Create - we need to know the parent. 16721da177e4SLinus Torvalds */ 16738737f3a1SAl Viro error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 16741da177e4SLinus Torvalds if (error) 1675a70e65dfSChristoph Hellwig return ERR_PTR(error); 16761da177e4SLinus Torvalds 16771da177e4SLinus Torvalds /* 16781da177e4SLinus Torvalds * We have the parent and last component. First of all, check 16791da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 16801da177e4SLinus Torvalds * will not do. 16811da177e4SLinus Torvalds */ 16821da177e4SLinus Torvalds error = -EISDIR; 1683a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 16848737f3a1SAl Viro goto exit_parent; 16851da177e4SLinus Torvalds 16868737f3a1SAl Viro error = -ENFILE; 16878737f3a1SAl Viro filp = get_empty_filp(); 16888737f3a1SAl Viro if (filp == NULL) 16898737f3a1SAl Viro goto exit_parent; 16908737f3a1SAl Viro nd.intent.open.file = filp; 16918737f3a1SAl Viro nd.intent.open.flags = flag; 16928737f3a1SAl Viro nd.intent.open.create_mode = mode; 1693a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1694a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 16958737f3a1SAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; 16963516586aSAl Viro if (flag & O_EXCL) 16973516586aSAl Viro nd.flags |= LOOKUP_EXCL; 16981b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1699a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1700a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 17011da177e4SLinus Torvalds 17021da177e4SLinus Torvalds do_last: 17034e7506e4SAl Viro error = PTR_ERR(path.dentry); 17044e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17051b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17061da177e4SLinus Torvalds goto exit; 17071da177e4SLinus Torvalds } 17081da177e4SLinus Torvalds 1709a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1710a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17114a3fd211SDave Hansen goto exit_mutex_unlock; 17124af4c52fSOleg Drokin } 17134af4c52fSOleg Drokin 17141da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17154e7506e4SAl Viro if (!path.dentry->d_inode) { 17164a3fd211SDave Hansen /* 17174a3fd211SDave Hansen * This write is needed to ensure that a 17184a3fd211SDave Hansen * ro->rw transition does not occur between 17194a3fd211SDave Hansen * the time when the file is created and when 17204a3fd211SDave Hansen * a permanent write count is taken through 17214a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17224a3fd211SDave Hansen */ 17234a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17241da177e4SLinus Torvalds if (error) 17254a3fd211SDave Hansen goto exit_mutex_unlock; 17264a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 17274a3fd211SDave Hansen if (error) { 17284a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17291da177e4SLinus Torvalds goto exit; 17304a3fd211SDave Hansen } 17314a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17324a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17334a3fd211SDave Hansen return filp; 17341da177e4SLinus Torvalds } 17351da177e4SLinus Torvalds 17361da177e4SLinus Torvalds /* 17371da177e4SLinus Torvalds * It already exists. 17381da177e4SLinus Torvalds */ 17391b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17405a190ae6SAl Viro audit_inode(pathname, path.dentry); 17411da177e4SLinus Torvalds 17421da177e4SLinus Torvalds error = -EEXIST; 17431da177e4SLinus Torvalds if (flag & O_EXCL) 17441da177e4SLinus Torvalds goto exit_dput; 17451da177e4SLinus Torvalds 1746e13b210fSAl Viro if (__follow_mount(&path)) { 17471da177e4SLinus Torvalds error = -ELOOP; 1748ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1749ba7a4c1aSAl Viro goto exit_dput; 17501da177e4SLinus Torvalds } 17513e2efce0SAmy Griffis 17521da177e4SLinus Torvalds error = -ENOENT; 17534e7506e4SAl Viro if (!path.dentry->d_inode) 17541da177e4SLinus Torvalds goto exit_dput; 17554e7506e4SAl Viro if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link) 17561da177e4SLinus Torvalds goto do_link; 17571da177e4SLinus Torvalds 1758a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 17591da177e4SLinus Torvalds error = -EISDIR; 17604e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 17611da177e4SLinus Torvalds goto exit; 17621da177e4SLinus Torvalds ok: 17634a3fd211SDave Hansen /* 17644a3fd211SDave Hansen * Consider: 17654a3fd211SDave Hansen * 1. may_open() truncates a file 17664a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 17674a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 17684a3fd211SDave Hansen * the ro mount. 17694a3fd211SDave Hansen * That would be inconsistent, and should 17704a3fd211SDave Hansen * be avoided. Taking this mnt write here 17714a3fd211SDave Hansen * ensures that (2) can not occur. 17724a3fd211SDave Hansen */ 17734a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 17744a3fd211SDave Hansen if (will_write) { 17754a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17761da177e4SLinus Torvalds if (error) 17771da177e4SLinus Torvalds goto exit; 17784a3fd211SDave Hansen } 17793fb64190SChristoph Hellwig error = may_open(&nd.path, acc_mode, flag); 17804a3fd211SDave Hansen if (error) { 17814a3fd211SDave Hansen if (will_write) 17824a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17834a3fd211SDave Hansen goto exit; 17844a3fd211SDave Hansen } 17854a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17864a3fd211SDave Hansen /* 17874a3fd211SDave Hansen * It is now safe to drop the mnt write 17884a3fd211SDave Hansen * because the filp has had a write taken 17894a3fd211SDave Hansen * on its behalf. 17904a3fd211SDave Hansen */ 17914a3fd211SDave Hansen if (will_write) 17924a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17934a3fd211SDave Hansen return filp; 17941da177e4SLinus Torvalds 17954a3fd211SDave Hansen exit_mutex_unlock: 17964a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 17971da177e4SLinus Torvalds exit_dput: 1798a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 17991da177e4SLinus Torvalds exit: 1800a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1801a70e65dfSChristoph Hellwig release_open_intent(&nd); 18028737f3a1SAl Viro exit_parent: 1803a70e65dfSChristoph Hellwig path_put(&nd.path); 1804a70e65dfSChristoph Hellwig return ERR_PTR(error); 18051da177e4SLinus Torvalds 18061da177e4SLinus Torvalds do_link: 18071da177e4SLinus Torvalds error = -ELOOP; 18081da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18091da177e4SLinus Torvalds goto exit_dput; 18101da177e4SLinus Torvalds /* 18111da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18121da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18131da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18141da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18151da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18161da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18171da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18181da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18191da177e4SLinus Torvalds */ 1820a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1821a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18221da177e4SLinus Torvalds if (error) 18231da177e4SLinus Torvalds goto exit_dput; 1824a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1825de459215SKirill Korotaev if (error) { 1826de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1827de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1828de459215SKirill Korotaev * with "intent.open". 1829de459215SKirill Korotaev */ 1830a70e65dfSChristoph Hellwig release_open_intent(&nd); 1831a70e65dfSChristoph Hellwig return ERR_PTR(error); 1832de459215SKirill Korotaev } 1833a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1834a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18351da177e4SLinus Torvalds goto ok; 18361da177e4SLinus Torvalds error = -EISDIR; 1837a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18381da177e4SLinus Torvalds goto exit; 1839a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1840a70e65dfSChristoph Hellwig __putname(nd.last.name); 18411da177e4SLinus Torvalds goto exit; 18421da177e4SLinus Torvalds } 18431da177e4SLinus Torvalds error = -ELOOP; 18441da177e4SLinus Torvalds if (count++==32) { 1845a70e65dfSChristoph Hellwig __putname(nd.last.name); 18461da177e4SLinus Torvalds goto exit; 18471da177e4SLinus Torvalds } 1848a70e65dfSChristoph Hellwig dir = nd.path.dentry; 18491b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1850a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1851a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1852a70e65dfSChristoph Hellwig __putname(nd.last.name); 18531da177e4SLinus Torvalds goto do_last; 18541da177e4SLinus Torvalds } 18551da177e4SLinus Torvalds 18561da177e4SLinus Torvalds /** 1857a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1858a70e65dfSChristoph Hellwig * 1859a70e65dfSChristoph Hellwig * @filename: path to open 1860a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1861a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1862a70e65dfSChristoph Hellwig * 1863a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1864a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1865a70e65dfSChristoph Hellwig * along, nothing to see here.. 1866a70e65dfSChristoph Hellwig */ 1867a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1868a70e65dfSChristoph Hellwig { 1869a70e65dfSChristoph Hellwig return do_filp_open(AT_FDCWD, filename, flags, mode); 1870a70e65dfSChristoph Hellwig } 1871a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1872a70e65dfSChristoph Hellwig 1873a70e65dfSChristoph Hellwig /** 18741da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 18751da177e4SLinus Torvalds * @nd: nameidata info 18761da177e4SLinus Torvalds * @is_dir: directory flag 18771da177e4SLinus Torvalds * 18781da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 18791da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1880c663e5d8SChristoph Hellwig * 18814ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 18821da177e4SLinus Torvalds */ 18831da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 18841da177e4SLinus Torvalds { 1885c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 18861da177e4SLinus Torvalds 18874ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1888c663e5d8SChristoph Hellwig /* 1889c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1890c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1891c663e5d8SChristoph Hellwig */ 18921da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 18931da177e4SLinus Torvalds goto fail; 18941da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 18953516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1896a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1897c663e5d8SChristoph Hellwig 1898c663e5d8SChristoph Hellwig /* 1899c663e5d8SChristoph Hellwig * Do the final lookup. 1900c663e5d8SChristoph Hellwig */ 190149705b77SChristoph Hellwig dentry = lookup_hash(nd); 19021da177e4SLinus Torvalds if (IS_ERR(dentry)) 19031da177e4SLinus Torvalds goto fail; 1904c663e5d8SChristoph Hellwig 1905e9baf6e5SAl Viro if (dentry->d_inode) 1906e9baf6e5SAl Viro goto eexist; 1907c663e5d8SChristoph Hellwig /* 1908c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1909c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1910c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1911c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1912c663e5d8SChristoph Hellwig */ 1913e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19141da177e4SLinus Torvalds dput(dentry); 19151da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1916e9baf6e5SAl Viro } 1917e9baf6e5SAl Viro return dentry; 1918e9baf6e5SAl Viro eexist: 1919e9baf6e5SAl Viro dput(dentry); 1920e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19211da177e4SLinus Torvalds fail: 19221da177e4SLinus Torvalds return dentry; 19231da177e4SLinus Torvalds } 1924f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19251da177e4SLinus Torvalds 19261da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19271da177e4SLinus Torvalds { 1928a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19291da177e4SLinus Torvalds 19301da177e4SLinus Torvalds if (error) 19311da177e4SLinus Torvalds return error; 19321da177e4SLinus Torvalds 19331da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19341da177e4SLinus Torvalds return -EPERM; 19351da177e4SLinus Torvalds 19361da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mknod) 19371da177e4SLinus Torvalds return -EPERM; 19381da177e4SLinus Torvalds 193908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 194008ce5f16SSerge E. Hallyn if (error) 194108ce5f16SSerge E. Hallyn return error; 194208ce5f16SSerge E. Hallyn 19431da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19441da177e4SLinus Torvalds if (error) 19451da177e4SLinus Torvalds return error; 19461da177e4SLinus Torvalds 19471da177e4SLinus Torvalds DQUOT_INIT(dir); 19481da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1949a74574aaSStephen Smalley if (!error) 1950f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19511da177e4SLinus Torvalds return error; 19521da177e4SLinus Torvalds } 19531da177e4SLinus Torvalds 1954463c3197SDave Hansen static int may_mknod(mode_t mode) 1955463c3197SDave Hansen { 1956463c3197SDave Hansen switch (mode & S_IFMT) { 1957463c3197SDave Hansen case S_IFREG: 1958463c3197SDave Hansen case S_IFCHR: 1959463c3197SDave Hansen case S_IFBLK: 1960463c3197SDave Hansen case S_IFIFO: 1961463c3197SDave Hansen case S_IFSOCK: 1962463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 1963463c3197SDave Hansen return 0; 1964463c3197SDave Hansen case S_IFDIR: 1965463c3197SDave Hansen return -EPERM; 1966463c3197SDave Hansen default: 1967463c3197SDave Hansen return -EINVAL; 1968463c3197SDave Hansen } 1969463c3197SDave Hansen } 1970463c3197SDave Hansen 19715590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 19725590ff0dSUlrich Drepper unsigned dev) 19731da177e4SLinus Torvalds { 19742ad94ae6SAl Viro int error; 19751da177e4SLinus Torvalds char *tmp; 19761da177e4SLinus Torvalds struct dentry *dentry; 19771da177e4SLinus Torvalds struct nameidata nd; 19781da177e4SLinus Torvalds 19791da177e4SLinus Torvalds if (S_ISDIR(mode)) 19801da177e4SLinus Torvalds return -EPERM; 19811da177e4SLinus Torvalds 19822ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 19831da177e4SLinus Torvalds if (error) 19842ad94ae6SAl Viro return error; 19852ad94ae6SAl Viro 19861da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 1987463c3197SDave Hansen if (IS_ERR(dentry)) { 19881da177e4SLinus Torvalds error = PTR_ERR(dentry); 1989463c3197SDave Hansen goto out_unlock; 1990463c3197SDave Hansen } 19914ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 19921da177e4SLinus Torvalds mode &= ~current->fs->umask; 1993463c3197SDave Hansen error = may_mknod(mode); 1994463c3197SDave Hansen if (error) 1995463c3197SDave Hansen goto out_dput; 1996463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 1997463c3197SDave Hansen if (error) 1998463c3197SDave Hansen goto out_dput; 1999be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2000be6d3e56SKentaro Takeda if (error) 2001be6d3e56SKentaro Takeda goto out_drop_write; 20021da177e4SLinus Torvalds switch (mode & S_IFMT) { 20031da177e4SLinus Torvalds case 0: case S_IFREG: 20044ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20051da177e4SLinus Torvalds break; 20061da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20074ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20081da177e4SLinus Torvalds new_decode_dev(dev)); 20091da177e4SLinus Torvalds break; 20101da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20114ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20121da177e4SLinus Torvalds break; 20131da177e4SLinus Torvalds } 2014be6d3e56SKentaro Takeda out_drop_write: 2015463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2016463c3197SDave Hansen out_dput: 20171da177e4SLinus Torvalds dput(dentry); 2018463c3197SDave Hansen out_unlock: 20194ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20201d957f9bSJan Blunck path_put(&nd.path); 20211da177e4SLinus Torvalds putname(tmp); 20221da177e4SLinus Torvalds 20231da177e4SLinus Torvalds return error; 20241da177e4SLinus Torvalds } 20251da177e4SLinus Torvalds 20265590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 20275590ff0dSUlrich Drepper { 20285590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20295590ff0dSUlrich Drepper } 20305590ff0dSUlrich Drepper 20311da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20321da177e4SLinus Torvalds { 2033a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20341da177e4SLinus Torvalds 20351da177e4SLinus Torvalds if (error) 20361da177e4SLinus Torvalds return error; 20371da177e4SLinus Torvalds 20381da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->mkdir) 20391da177e4SLinus Torvalds return -EPERM; 20401da177e4SLinus Torvalds 20411da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20421da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20431da177e4SLinus Torvalds if (error) 20441da177e4SLinus Torvalds return error; 20451da177e4SLinus Torvalds 20461da177e4SLinus Torvalds DQUOT_INIT(dir); 20471da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2048a74574aaSStephen Smalley if (!error) 2049f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20501da177e4SLinus Torvalds return error; 20511da177e4SLinus Torvalds } 20521da177e4SLinus Torvalds 20535590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 20541da177e4SLinus Torvalds { 20551da177e4SLinus Torvalds int error = 0; 20561da177e4SLinus Torvalds char * tmp; 20576902d925SDave Hansen struct dentry *dentry; 20586902d925SDave Hansen struct nameidata nd; 20591da177e4SLinus Torvalds 20602ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 20612ad94ae6SAl Viro if (error) 20626902d925SDave Hansen goto out_err; 20631da177e4SLinus Torvalds 20641da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20651da177e4SLinus Torvalds error = PTR_ERR(dentry); 20666902d925SDave Hansen if (IS_ERR(dentry)) 20676902d925SDave Hansen goto out_unlock; 20686902d925SDave Hansen 20694ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20701da177e4SLinus Torvalds mode &= ~current->fs->umask; 2071463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2072463c3197SDave Hansen if (error) 2073463c3197SDave Hansen goto out_dput; 2074be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2075be6d3e56SKentaro Takeda if (error) 2076be6d3e56SKentaro Takeda goto out_drop_write; 20774ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2078be6d3e56SKentaro Takeda out_drop_write: 2079463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2080463c3197SDave Hansen out_dput: 20811da177e4SLinus Torvalds dput(dentry); 20826902d925SDave Hansen out_unlock: 20834ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20841d957f9bSJan Blunck path_put(&nd.path); 20851da177e4SLinus Torvalds putname(tmp); 20866902d925SDave Hansen out_err: 20871da177e4SLinus Torvalds return error; 20881da177e4SLinus Torvalds } 20891da177e4SLinus Torvalds 20905590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 20915590ff0dSUlrich Drepper { 20925590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 20935590ff0dSUlrich Drepper } 20945590ff0dSUlrich Drepper 20951da177e4SLinus Torvalds /* 20961da177e4SLinus Torvalds * We try to drop the dentry early: we should have 20971da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 20981da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 20991da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21001da177e4SLinus Torvalds * 21011da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21021da177e4SLinus Torvalds * do a 21031da177e4SLinus Torvalds * 21041da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21051da177e4SLinus Torvalds * return -EBUSY; 21061da177e4SLinus Torvalds * 21071da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21081da177e4SLinus Torvalds * that is still in use by something else.. 21091da177e4SLinus Torvalds */ 21101da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21111da177e4SLinus Torvalds { 21121da177e4SLinus Torvalds dget(dentry); 21131da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21141da177e4SLinus Torvalds spin_lock(&dcache_lock); 21151da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21161da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21171da177e4SLinus Torvalds __d_drop(dentry); 21181da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21191da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21201da177e4SLinus Torvalds } 21211da177e4SLinus Torvalds 21221da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21231da177e4SLinus Torvalds { 21241da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21251da177e4SLinus Torvalds 21261da177e4SLinus Torvalds if (error) 21271da177e4SLinus Torvalds return error; 21281da177e4SLinus Torvalds 21291da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->rmdir) 21301da177e4SLinus Torvalds return -EPERM; 21311da177e4SLinus Torvalds 21321da177e4SLinus Torvalds DQUOT_INIT(dir); 21331da177e4SLinus Torvalds 21341b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21351da177e4SLinus Torvalds dentry_unhash(dentry); 21361da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21371da177e4SLinus Torvalds error = -EBUSY; 21381da177e4SLinus Torvalds else { 21391da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21401da177e4SLinus Torvalds if (!error) { 21411da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21421da177e4SLinus Torvalds if (!error) 21431da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21441da177e4SLinus Torvalds } 21451da177e4SLinus Torvalds } 21461b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21471da177e4SLinus Torvalds if (!error) { 21481da177e4SLinus Torvalds d_delete(dentry); 21491da177e4SLinus Torvalds } 21501da177e4SLinus Torvalds dput(dentry); 21511da177e4SLinus Torvalds 21521da177e4SLinus Torvalds return error; 21531da177e4SLinus Torvalds } 21541da177e4SLinus Torvalds 21555590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21561da177e4SLinus Torvalds { 21571da177e4SLinus Torvalds int error = 0; 21581da177e4SLinus Torvalds char * name; 21591da177e4SLinus Torvalds struct dentry *dentry; 21601da177e4SLinus Torvalds struct nameidata nd; 21611da177e4SLinus Torvalds 21622ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 21631da177e4SLinus Torvalds if (error) 21642ad94ae6SAl Viro return error; 21651da177e4SLinus Torvalds 21661da177e4SLinus Torvalds switch(nd.last_type) { 21671da177e4SLinus Torvalds case LAST_DOTDOT: 21681da177e4SLinus Torvalds error = -ENOTEMPTY; 21691da177e4SLinus Torvalds goto exit1; 21701da177e4SLinus Torvalds case LAST_DOT: 21711da177e4SLinus Torvalds error = -EINVAL; 21721da177e4SLinus Torvalds goto exit1; 21731da177e4SLinus Torvalds case LAST_ROOT: 21741da177e4SLinus Torvalds error = -EBUSY; 21751da177e4SLinus Torvalds goto exit1; 21761da177e4SLinus Torvalds } 21770612d9fbSOGAWA Hirofumi 21780612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 21790612d9fbSOGAWA Hirofumi 21804ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 218149705b77SChristoph Hellwig dentry = lookup_hash(&nd); 21821da177e4SLinus Torvalds error = PTR_ERR(dentry); 21836902d925SDave Hansen if (IS_ERR(dentry)) 21846902d925SDave Hansen goto exit2; 21850622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 21860622753bSDave Hansen if (error) 21870622753bSDave Hansen goto exit3; 2188be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2189be6d3e56SKentaro Takeda if (error) 2190be6d3e56SKentaro Takeda goto exit4; 21914ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2192be6d3e56SKentaro Takeda exit4: 21930622753bSDave Hansen mnt_drop_write(nd.path.mnt); 21940622753bSDave Hansen exit3: 21951da177e4SLinus Torvalds dput(dentry); 21966902d925SDave Hansen exit2: 21974ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21981da177e4SLinus Torvalds exit1: 21991d957f9bSJan Blunck path_put(&nd.path); 22001da177e4SLinus Torvalds putname(name); 22011da177e4SLinus Torvalds return error; 22021da177e4SLinus Torvalds } 22031da177e4SLinus Torvalds 22045590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 22055590ff0dSUlrich Drepper { 22065590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22075590ff0dSUlrich Drepper } 22085590ff0dSUlrich Drepper 22091da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22101da177e4SLinus Torvalds { 22111da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22121da177e4SLinus Torvalds 22131da177e4SLinus Torvalds if (error) 22141da177e4SLinus Torvalds return error; 22151da177e4SLinus Torvalds 22161da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->unlink) 22171da177e4SLinus Torvalds return -EPERM; 22181da177e4SLinus Torvalds 22191da177e4SLinus Torvalds DQUOT_INIT(dir); 22201da177e4SLinus Torvalds 22211b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22221da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22231da177e4SLinus Torvalds error = -EBUSY; 22241da177e4SLinus Torvalds else { 22251da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22261da177e4SLinus Torvalds if (!error) 22271da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22281da177e4SLinus Torvalds } 22291b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22301da177e4SLinus Torvalds 22311da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22321da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2233ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22341da177e4SLinus Torvalds d_delete(dentry); 22351da177e4SLinus Torvalds } 22360eeca283SRobert Love 22371da177e4SLinus Torvalds return error; 22381da177e4SLinus Torvalds } 22391da177e4SLinus Torvalds 22401da177e4SLinus Torvalds /* 22411da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22421b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22431da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22441da177e4SLinus Torvalds * while waiting on the I/O. 22451da177e4SLinus Torvalds */ 22465590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22471da177e4SLinus Torvalds { 22482ad94ae6SAl Viro int error; 22491da177e4SLinus Torvalds char *name; 22501da177e4SLinus Torvalds struct dentry *dentry; 22511da177e4SLinus Torvalds struct nameidata nd; 22521da177e4SLinus Torvalds struct inode *inode = NULL; 22531da177e4SLinus Torvalds 22542ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22551da177e4SLinus Torvalds if (error) 22562ad94ae6SAl Viro return error; 22572ad94ae6SAl Viro 22581da177e4SLinus Torvalds error = -EISDIR; 22591da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22601da177e4SLinus Torvalds goto exit1; 22610612d9fbSOGAWA Hirofumi 22620612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22630612d9fbSOGAWA Hirofumi 22644ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 226549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22661da177e4SLinus Torvalds error = PTR_ERR(dentry); 22671da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22681da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 22691da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 22701da177e4SLinus Torvalds goto slashes; 22711da177e4SLinus Torvalds inode = dentry->d_inode; 22721da177e4SLinus Torvalds if (inode) 22731da177e4SLinus Torvalds atomic_inc(&inode->i_count); 22740622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22750622753bSDave Hansen if (error) 22760622753bSDave Hansen goto exit2; 2277be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2278be6d3e56SKentaro Takeda if (error) 2279be6d3e56SKentaro Takeda goto exit3; 22804ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2281be6d3e56SKentaro Takeda exit3: 22820622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22831da177e4SLinus Torvalds exit2: 22841da177e4SLinus Torvalds dput(dentry); 22851da177e4SLinus Torvalds } 22864ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22871da177e4SLinus Torvalds if (inode) 22881da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 22891da177e4SLinus Torvalds exit1: 22901d957f9bSJan Blunck path_put(&nd.path); 22911da177e4SLinus Torvalds putname(name); 22921da177e4SLinus Torvalds return error; 22931da177e4SLinus Torvalds 22941da177e4SLinus Torvalds slashes: 22951da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 22961da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 22971da177e4SLinus Torvalds goto exit2; 22981da177e4SLinus Torvalds } 22991da177e4SLinus Torvalds 23005590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 23015590ff0dSUlrich Drepper { 23025590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23035590ff0dSUlrich Drepper return -EINVAL; 23045590ff0dSUlrich Drepper 23055590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23065590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23075590ff0dSUlrich Drepper 23085590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23095590ff0dSUlrich Drepper } 23105590ff0dSUlrich Drepper 23115590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 23125590ff0dSUlrich Drepper { 23135590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23145590ff0dSUlrich Drepper } 23155590ff0dSUlrich Drepper 2316db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23171da177e4SLinus Torvalds { 2318a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23191da177e4SLinus Torvalds 23201da177e4SLinus Torvalds if (error) 23211da177e4SLinus Torvalds return error; 23221da177e4SLinus Torvalds 23231da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->symlink) 23241da177e4SLinus Torvalds return -EPERM; 23251da177e4SLinus Torvalds 23261da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23271da177e4SLinus Torvalds if (error) 23281da177e4SLinus Torvalds return error; 23291da177e4SLinus Torvalds 23301da177e4SLinus Torvalds DQUOT_INIT(dir); 23311da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2332a74574aaSStephen Smalley if (!error) 2333f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23341da177e4SLinus Torvalds return error; 23351da177e4SLinus Torvalds } 23361da177e4SLinus Torvalds 23375590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 23385590ff0dSUlrich Drepper int newdfd, const char __user *newname) 23391da177e4SLinus Torvalds { 23402ad94ae6SAl Viro int error; 23411da177e4SLinus Torvalds char *from; 23421da177e4SLinus Torvalds char *to; 23436902d925SDave Hansen struct dentry *dentry; 23446902d925SDave Hansen struct nameidata nd; 23451da177e4SLinus Torvalds 23461da177e4SLinus Torvalds from = getname(oldname); 23471da177e4SLinus Torvalds if (IS_ERR(from)) 23481da177e4SLinus Torvalds return PTR_ERR(from); 23492ad94ae6SAl Viro 23502ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 23512ad94ae6SAl Viro if (error) 23526902d925SDave Hansen goto out_putname; 23531da177e4SLinus Torvalds 23541da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23551da177e4SLinus Torvalds error = PTR_ERR(dentry); 23566902d925SDave Hansen if (IS_ERR(dentry)) 23576902d925SDave Hansen goto out_unlock; 23586902d925SDave Hansen 235975c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 236075c3f29dSDave Hansen if (error) 236175c3f29dSDave Hansen goto out_dput; 2362be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2363be6d3e56SKentaro Takeda if (error) 2364be6d3e56SKentaro Takeda goto out_drop_write; 2365db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2366be6d3e56SKentaro Takeda out_drop_write: 236775c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 236875c3f29dSDave Hansen out_dput: 23691da177e4SLinus Torvalds dput(dentry); 23706902d925SDave Hansen out_unlock: 23714ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23721d957f9bSJan Blunck path_put(&nd.path); 23731da177e4SLinus Torvalds putname(to); 23746902d925SDave Hansen out_putname: 23751da177e4SLinus Torvalds putname(from); 23761da177e4SLinus Torvalds return error; 23771da177e4SLinus Torvalds } 23781da177e4SLinus Torvalds 23795590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 23805590ff0dSUlrich Drepper { 23815590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 23825590ff0dSUlrich Drepper } 23835590ff0dSUlrich Drepper 23841da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 23851da177e4SLinus Torvalds { 23861da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 23871da177e4SLinus Torvalds int error; 23881da177e4SLinus Torvalds 23891da177e4SLinus Torvalds if (!inode) 23901da177e4SLinus Torvalds return -ENOENT; 23911da177e4SLinus Torvalds 2392a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 23931da177e4SLinus Torvalds if (error) 23941da177e4SLinus Torvalds return error; 23951da177e4SLinus Torvalds 23961da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 23971da177e4SLinus Torvalds return -EXDEV; 23981da177e4SLinus Torvalds 23991da177e4SLinus Torvalds /* 24001da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24011da177e4SLinus Torvalds */ 24021da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24031da177e4SLinus Torvalds return -EPERM; 24041da177e4SLinus Torvalds if (!dir->i_op || !dir->i_op->link) 24051da177e4SLinus Torvalds return -EPERM; 24067e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24071da177e4SLinus Torvalds return -EPERM; 24081da177e4SLinus Torvalds 24091da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24101da177e4SLinus Torvalds if (error) 24111da177e4SLinus Torvalds return error; 24121da177e4SLinus Torvalds 24137e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24141da177e4SLinus Torvalds DQUOT_INIT(dir); 24151da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24167e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2417e31e14ecSStephen Smalley if (!error) 24187e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24191da177e4SLinus Torvalds return error; 24201da177e4SLinus Torvalds } 24211da177e4SLinus Torvalds 24221da177e4SLinus Torvalds /* 24231da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24241da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24251da177e4SLinus Torvalds * newname. --KAB 24261da177e4SLinus Torvalds * 24271da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24281da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24291da177e4SLinus Torvalds * and other special files. --ADM 24301da177e4SLinus Torvalds */ 24315590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2432c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2433c04030e1SUlrich Drepper int flags) 24341da177e4SLinus Torvalds { 24351da177e4SLinus Torvalds struct dentry *new_dentry; 24362d8f3038SAl Viro struct nameidata nd; 24372d8f3038SAl Viro struct path old_path; 24381da177e4SLinus Torvalds int error; 24391da177e4SLinus Torvalds char *to; 24401da177e4SLinus Torvalds 244145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2442c04030e1SUlrich Drepper return -EINVAL; 2443c04030e1SUlrich Drepper 24442d8f3038SAl Viro error = user_path_at(olddfd, oldname, 244545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24462d8f3038SAl Viro &old_path); 24471da177e4SLinus Torvalds if (error) 24482ad94ae6SAl Viro return error; 24492ad94ae6SAl Viro 24502ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24511da177e4SLinus Torvalds if (error) 24521da177e4SLinus Torvalds goto out; 24531da177e4SLinus Torvalds error = -EXDEV; 24542d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 24551da177e4SLinus Torvalds goto out_release; 24561da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24571da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24586902d925SDave Hansen if (IS_ERR(new_dentry)) 24596902d925SDave Hansen goto out_unlock; 246075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 246175c3f29dSDave Hansen if (error) 246275c3f29dSDave Hansen goto out_dput; 2463be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2464be6d3e56SKentaro Takeda if (error) 2465be6d3e56SKentaro Takeda goto out_drop_write; 24662d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2467be6d3e56SKentaro Takeda out_drop_write: 246875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 246975c3f29dSDave Hansen out_dput: 24701da177e4SLinus Torvalds dput(new_dentry); 24716902d925SDave Hansen out_unlock: 24724ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24731da177e4SLinus Torvalds out_release: 24741d957f9bSJan Blunck path_put(&nd.path); 24752ad94ae6SAl Viro putname(to); 24761da177e4SLinus Torvalds out: 24772d8f3038SAl Viro path_put(&old_path); 24781da177e4SLinus Torvalds 24791da177e4SLinus Torvalds return error; 24801da177e4SLinus Torvalds } 24811da177e4SLinus Torvalds 24825590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 24835590ff0dSUlrich Drepper { 2484c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 24855590ff0dSUlrich Drepper } 24865590ff0dSUlrich Drepper 24871da177e4SLinus Torvalds /* 24881da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 24891da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 24901da177e4SLinus Torvalds * Problems: 24911da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 24921da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 24931da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2494a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 24951da177e4SLinus Torvalds * story. 24961da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 24971b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 24981da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 24991da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2500a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25011da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25021da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25031da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2504a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 25051da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25061da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25071da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25081da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25091da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25101da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25111da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25121da177e4SLinus Torvalds * trick as in rmdir(). 25131da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25141b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25151da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25161b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25171da177e4SLinus Torvalds * locking]. 25181da177e4SLinus Torvalds */ 251975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25201da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25211da177e4SLinus Torvalds { 25221da177e4SLinus Torvalds int error = 0; 25231da177e4SLinus Torvalds struct inode *target; 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds /* 25261da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25271da177e4SLinus Torvalds * we'll need to flip '..'. 25281da177e4SLinus Torvalds */ 25291da177e4SLinus Torvalds if (new_dir != old_dir) { 2530f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25311da177e4SLinus Torvalds if (error) 25321da177e4SLinus Torvalds return error; 25331da177e4SLinus Torvalds } 25341da177e4SLinus Torvalds 25351da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25361da177e4SLinus Torvalds if (error) 25371da177e4SLinus Torvalds return error; 25381da177e4SLinus Torvalds 25391da177e4SLinus Torvalds target = new_dentry->d_inode; 25401da177e4SLinus Torvalds if (target) { 25411b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25421da177e4SLinus Torvalds dentry_unhash(new_dentry); 25431da177e4SLinus Torvalds } 25441da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25451da177e4SLinus Torvalds error = -EBUSY; 25461da177e4SLinus Torvalds else 25471da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25481da177e4SLinus Torvalds if (target) { 25491da177e4SLinus Torvalds if (!error) 25501da177e4SLinus Torvalds target->i_flags |= S_DEAD; 25511b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25521da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 25531da177e4SLinus Torvalds d_rehash(new_dentry); 25541da177e4SLinus Torvalds dput(new_dentry); 25551da177e4SLinus Torvalds } 2556e31e14ecSStephen Smalley if (!error) 2557349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25581da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25591da177e4SLinus Torvalds return error; 25601da177e4SLinus Torvalds } 25611da177e4SLinus Torvalds 256275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25631da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25641da177e4SLinus Torvalds { 25651da177e4SLinus Torvalds struct inode *target; 25661da177e4SLinus Torvalds int error; 25671da177e4SLinus Torvalds 25681da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25691da177e4SLinus Torvalds if (error) 25701da177e4SLinus Torvalds return error; 25711da177e4SLinus Torvalds 25721da177e4SLinus Torvalds dget(new_dentry); 25731da177e4SLinus Torvalds target = new_dentry->d_inode; 25741da177e4SLinus Torvalds if (target) 25751b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25761da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25771da177e4SLinus Torvalds error = -EBUSY; 25781da177e4SLinus Torvalds else 25791da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25801da177e4SLinus Torvalds if (!error) { 2581349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25821da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 25831da177e4SLinus Torvalds } 25841da177e4SLinus Torvalds if (target) 25851b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25861da177e4SLinus Torvalds dput(new_dentry); 25871da177e4SLinus Torvalds return error; 25881da177e4SLinus Torvalds } 25891da177e4SLinus Torvalds 25901da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 25911da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25921da177e4SLinus Torvalds { 25931da177e4SLinus Torvalds int error; 25941da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 25950eeca283SRobert Love const char *old_name; 25961da177e4SLinus Torvalds 25971da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 25981da177e4SLinus Torvalds return 0; 25991da177e4SLinus Torvalds 26001da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26011da177e4SLinus Torvalds if (error) 26021da177e4SLinus Torvalds return error; 26031da177e4SLinus Torvalds 26041da177e4SLinus Torvalds if (!new_dentry->d_inode) 2605a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 26061da177e4SLinus Torvalds else 26071da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26081da177e4SLinus Torvalds if (error) 26091da177e4SLinus Torvalds return error; 26101da177e4SLinus Torvalds 26111da177e4SLinus Torvalds if (!old_dir->i_op || !old_dir->i_op->rename) 26121da177e4SLinus Torvalds return -EPERM; 26131da177e4SLinus Torvalds 26141da177e4SLinus Torvalds DQUOT_INIT(old_dir); 26151da177e4SLinus Torvalds DQUOT_INIT(new_dir); 26161da177e4SLinus Torvalds 26170eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26180eeca283SRobert Love 26191da177e4SLinus Torvalds if (is_dir) 26201da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26211da177e4SLinus Torvalds else 26221da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26231da177e4SLinus Torvalds if (!error) { 26240eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 262589204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26265a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26271da177e4SLinus Torvalds } 26280eeca283SRobert Love fsnotify_oldname_free(old_name); 26290eeca283SRobert Love 26301da177e4SLinus Torvalds return error; 26311da177e4SLinus Torvalds } 26321da177e4SLinus Torvalds 26332ad94ae6SAl Viro asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 26342ad94ae6SAl Viro int newdfd, const char __user *newname) 26351da177e4SLinus Torvalds { 26361da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26371da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26381da177e4SLinus Torvalds struct dentry *trap; 26391da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26402ad94ae6SAl Viro char *from; 26412ad94ae6SAl Viro char *to; 26422ad94ae6SAl Viro int error; 26431da177e4SLinus Torvalds 26442ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26451da177e4SLinus Torvalds if (error) 26461da177e4SLinus Torvalds goto exit; 26471da177e4SLinus Torvalds 26482ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 26491da177e4SLinus Torvalds if (error) 26501da177e4SLinus Torvalds goto exit1; 26511da177e4SLinus Torvalds 26521da177e4SLinus Torvalds error = -EXDEV; 26534ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 26541da177e4SLinus Torvalds goto exit2; 26551da177e4SLinus Torvalds 26564ac91378SJan Blunck old_dir = oldnd.path.dentry; 26571da177e4SLinus Torvalds error = -EBUSY; 26581da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 26591da177e4SLinus Torvalds goto exit2; 26601da177e4SLinus Torvalds 26614ac91378SJan Blunck new_dir = newnd.path.dentry; 26621da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26631da177e4SLinus Torvalds goto exit2; 26641da177e4SLinus Torvalds 26650612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 26660612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 26674e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 26680612d9fbSOGAWA Hirofumi 26691da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 26701da177e4SLinus Torvalds 267149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 26721da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 26731da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 26741da177e4SLinus Torvalds goto exit3; 26751da177e4SLinus Torvalds /* source must exist */ 26761da177e4SLinus Torvalds error = -ENOENT; 26771da177e4SLinus Torvalds if (!old_dentry->d_inode) 26781da177e4SLinus Torvalds goto exit4; 26791da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 26801da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 26811da177e4SLinus Torvalds error = -ENOTDIR; 26821da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 26831da177e4SLinus Torvalds goto exit4; 26841da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 26851da177e4SLinus Torvalds goto exit4; 26861da177e4SLinus Torvalds } 26871da177e4SLinus Torvalds /* source should not be ancestor of target */ 26881da177e4SLinus Torvalds error = -EINVAL; 26891da177e4SLinus Torvalds if (old_dentry == trap) 26901da177e4SLinus Torvalds goto exit4; 269149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 26921da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 26931da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 26941da177e4SLinus Torvalds goto exit4; 26951da177e4SLinus Torvalds /* target should not be an ancestor of source */ 26961da177e4SLinus Torvalds error = -ENOTEMPTY; 26971da177e4SLinus Torvalds if (new_dentry == trap) 26981da177e4SLinus Torvalds goto exit5; 26991da177e4SLinus Torvalds 27009079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27019079b1ebSDave Hansen if (error) 27029079b1ebSDave Hansen goto exit5; 2703be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 2704be6d3e56SKentaro Takeda &newnd.path, new_dentry); 2705be6d3e56SKentaro Takeda if (error) 2706be6d3e56SKentaro Takeda goto exit6; 27071da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27081da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 2709be6d3e56SKentaro Takeda exit6: 27109079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27111da177e4SLinus Torvalds exit5: 27121da177e4SLinus Torvalds dput(new_dentry); 27131da177e4SLinus Torvalds exit4: 27141da177e4SLinus Torvalds dput(old_dentry); 27151da177e4SLinus Torvalds exit3: 27161da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27171da177e4SLinus Torvalds exit2: 27181d957f9bSJan Blunck path_put(&newnd.path); 27192ad94ae6SAl Viro putname(to); 27201da177e4SLinus Torvalds exit1: 27211d957f9bSJan Blunck path_put(&oldnd.path); 27221da177e4SLinus Torvalds putname(from); 27232ad94ae6SAl Viro exit: 27241da177e4SLinus Torvalds return error; 27251da177e4SLinus Torvalds } 27261da177e4SLinus Torvalds 27275590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 27285590ff0dSUlrich Drepper { 27295590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27305590ff0dSUlrich Drepper } 27315590ff0dSUlrich Drepper 27321da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27331da177e4SLinus Torvalds { 27341da177e4SLinus Torvalds int len; 27351da177e4SLinus Torvalds 27361da177e4SLinus Torvalds len = PTR_ERR(link); 27371da177e4SLinus Torvalds if (IS_ERR(link)) 27381da177e4SLinus Torvalds goto out; 27391da177e4SLinus Torvalds 27401da177e4SLinus Torvalds len = strlen(link); 27411da177e4SLinus Torvalds if (len > (unsigned) buflen) 27421da177e4SLinus Torvalds len = buflen; 27431da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27441da177e4SLinus Torvalds len = -EFAULT; 27451da177e4SLinus Torvalds out: 27461da177e4SLinus Torvalds return len; 27471da177e4SLinus Torvalds } 27481da177e4SLinus Torvalds 27491da177e4SLinus Torvalds /* 27501da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 27511da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 27521da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 27531da177e4SLinus Torvalds */ 27541da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27551da177e4SLinus Torvalds { 27561da177e4SLinus Torvalds struct nameidata nd; 2757cc314eefSLinus Torvalds void *cookie; 2758694a1764SMarcin Slusarz int res; 2759cc314eefSLinus Torvalds 27601da177e4SLinus Torvalds nd.depth = 0; 2761cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2762694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2763694a1764SMarcin Slusarz return PTR_ERR(cookie); 2764694a1764SMarcin Slusarz 2765694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27661da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2767cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2768694a1764SMarcin Slusarz return res; 27691da177e4SLinus Torvalds } 27701da177e4SLinus Torvalds 27711da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 27721da177e4SLinus Torvalds { 27731da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 27741da177e4SLinus Torvalds } 27751da177e4SLinus Torvalds 27761da177e4SLinus Torvalds /* get the link contents into pagecache */ 27771da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 27781da177e4SLinus Torvalds { 2779ebd09abbSDuane Griffin char *kaddr; 27801da177e4SLinus Torvalds struct page *page; 27811da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2782090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 27831da177e4SLinus Torvalds if (IS_ERR(page)) 27846fe6900eSNick Piggin return (char*)page; 27851da177e4SLinus Torvalds *ppage = page; 2786ebd09abbSDuane Griffin kaddr = kmap(page); 2787ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 2788ebd09abbSDuane Griffin return kaddr; 27891da177e4SLinus Torvalds } 27901da177e4SLinus Torvalds 27911da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27921da177e4SLinus Torvalds { 27931da177e4SLinus Torvalds struct page *page = NULL; 27941da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 27951da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 27961da177e4SLinus Torvalds if (page) { 27971da177e4SLinus Torvalds kunmap(page); 27981da177e4SLinus Torvalds page_cache_release(page); 27991da177e4SLinus Torvalds } 28001da177e4SLinus Torvalds return res; 28011da177e4SLinus Torvalds } 28021da177e4SLinus Torvalds 2803cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 28041da177e4SLinus Torvalds { 2805cc314eefSLinus Torvalds struct page *page = NULL; 28061da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2807cc314eefSLinus Torvalds return page; 28081da177e4SLinus Torvalds } 28091da177e4SLinus Torvalds 2810cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28111da177e4SLinus Torvalds { 2812cc314eefSLinus Torvalds struct page *page = cookie; 2813cc314eefSLinus Torvalds 2814cc314eefSLinus Torvalds if (page) { 28151da177e4SLinus Torvalds kunmap(page); 28161da177e4SLinus Torvalds page_cache_release(page); 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds } 28191da177e4SLinus Torvalds 28200adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 28210adb25d2SKirill Korotaev gfp_t gfp_mask) 28221da177e4SLinus Torvalds { 28231da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28240adb25d2SKirill Korotaev struct page *page; 2825afddba49SNick Piggin void *fsdata; 2826beb497abSDmitriy Monakhov int err; 28271da177e4SLinus Torvalds char *kaddr; 28281da177e4SLinus Torvalds 28297e53cac4SNeilBrown retry: 2830afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2831afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 28321da177e4SLinus Torvalds if (err) 2833afddba49SNick Piggin goto fail; 2834afddba49SNick Piggin 28351da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28361da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28371da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2838afddba49SNick Piggin 2839afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2840afddba49SNick Piggin page, fsdata); 28411da177e4SLinus Torvalds if (err < 0) 28421da177e4SLinus Torvalds goto fail; 2843afddba49SNick Piggin if (err < len-1) 2844afddba49SNick Piggin goto retry; 2845afddba49SNick Piggin 28461da177e4SLinus Torvalds mark_inode_dirty(inode); 28471da177e4SLinus Torvalds return 0; 28481da177e4SLinus Torvalds fail: 28491da177e4SLinus Torvalds return err; 28501da177e4SLinus Torvalds } 28511da177e4SLinus Torvalds 28520adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 28530adb25d2SKirill Korotaev { 28540adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 28550adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 28560adb25d2SKirill Korotaev } 28570adb25d2SKirill Korotaev 285892e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 28591da177e4SLinus Torvalds .readlink = generic_readlink, 28601da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28611da177e4SLinus Torvalds .put_link = page_put_link, 28621da177e4SLinus Torvalds }; 28631da177e4SLinus Torvalds 28642d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 28651da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 28661da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 28671da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 28681da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 28691da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 28701da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 28711da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 28721da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 28731da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 28740adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 28751da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 28761da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 28771da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2878d1811465SAl Viro EXPORT_SYMBOL(kern_path); 287916f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2880f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 28818c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 28821da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 28831da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 28841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 28851da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 28861da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 28871da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 28881da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 28891da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 28901da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 28911da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 28921da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 28931da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 28941da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 28951da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2896