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 260acfa4380SAl Viro if (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 435acfa4380SAl Viro if (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 9121da177e4SLinus Torvalds if (inode->i_op->follow_link) { 91390ebe565SAl Viro err = do_follow_link(&next, nd); 9141da177e4SLinus Torvalds if (err) 9151da177e4SLinus Torvalds goto return_err; 9161da177e4SLinus Torvalds err = -ENOENT; 9174ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9181da177e4SLinus Torvalds if (!inode) 9191da177e4SLinus Torvalds break; 92009dd17d3SMiklos Szeredi } else 92109dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9221da177e4SLinus Torvalds err = -ENOTDIR; 9231da177e4SLinus Torvalds if (!inode->i_op->lookup) 9241da177e4SLinus Torvalds break; 9251da177e4SLinus Torvalds continue; 9261da177e4SLinus Torvalds /* here ends the main loop */ 9271da177e4SLinus Torvalds 9281da177e4SLinus Torvalds last_with_slashes: 9291da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9301da177e4SLinus Torvalds last_component: 931f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 932f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9331da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9341da177e4SLinus Torvalds goto lookup_parent; 9351da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9361da177e4SLinus Torvalds default: 9371da177e4SLinus Torvalds break; 9381da177e4SLinus Torvalds case 2: 9391da177e4SLinus Torvalds if (this.name[1] != '.') 9401da177e4SLinus Torvalds break; 94158c465ebSAl Viro follow_dotdot(nd); 9424ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9431da177e4SLinus Torvalds /* fallthrough */ 9441da177e4SLinus Torvalds case 1: 9451da177e4SLinus Torvalds goto return_reval; 9461da177e4SLinus Torvalds } 9474ac91378SJan Blunck if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 9484ac91378SJan Blunck err = nd->path.dentry->d_op->d_hash(nd->path.dentry, 9494ac91378SJan Blunck &this); 9501da177e4SLinus Torvalds if (err < 0) 9511da177e4SLinus Torvalds break; 9521da177e4SLinus Torvalds } 9531da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9541da177e4SLinus Torvalds if (err) 9551da177e4SLinus Torvalds break; 9561da177e4SLinus Torvalds inode = next.dentry->d_inode; 9571da177e4SLinus Torvalds if ((lookup_flags & LOOKUP_FOLLOW) 958acfa4380SAl Viro && inode && inode->i_op->follow_link) { 95990ebe565SAl Viro err = do_follow_link(&next, nd); 9601da177e4SLinus Torvalds if (err) 9611da177e4SLinus Torvalds goto return_err; 9624ac91378SJan Blunck inode = nd->path.dentry->d_inode; 96309dd17d3SMiklos Szeredi } else 96409dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9651da177e4SLinus Torvalds err = -ENOENT; 9661da177e4SLinus Torvalds if (!inode) 9671da177e4SLinus Torvalds break; 9681da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9691da177e4SLinus Torvalds err = -ENOTDIR; 970acfa4380SAl Viro if (!inode->i_op->lookup) 9711da177e4SLinus Torvalds break; 9721da177e4SLinus Torvalds } 9731da177e4SLinus Torvalds goto return_base; 9741da177e4SLinus Torvalds lookup_parent: 9751da177e4SLinus Torvalds nd->last = this; 9761da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9771da177e4SLinus Torvalds if (this.name[0] != '.') 9781da177e4SLinus Torvalds goto return_base; 9791da177e4SLinus Torvalds if (this.len == 1) 9801da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9811da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9821da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9831da177e4SLinus Torvalds else 9841da177e4SLinus Torvalds goto return_base; 9851da177e4SLinus Torvalds return_reval: 9861da177e4SLinus Torvalds /* 9871da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 9881da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 9891da177e4SLinus Torvalds */ 9904ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 9914ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 9921da177e4SLinus Torvalds err = -ESTALE; 9931da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 9944ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 9954ac91378SJan Blunck nd->path.dentry, nd)) 9961da177e4SLinus Torvalds break; 9971da177e4SLinus Torvalds } 9981da177e4SLinus Torvalds return_base: 9991da177e4SLinus Torvalds return 0; 10001da177e4SLinus Torvalds out_dput: 10011d957f9bSJan Blunck path_put_conditional(&next, nd); 10021da177e4SLinus Torvalds break; 10031da177e4SLinus Torvalds } 10041d957f9bSJan Blunck path_put(&nd->path); 10051da177e4SLinus Torvalds return_err: 10061da177e4SLinus Torvalds return err; 10071da177e4SLinus Torvalds } 10081da177e4SLinus Torvalds 1009fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10101da177e4SLinus Torvalds { 10111da177e4SLinus Torvalds current->total_link_count = 0; 10121da177e4SLinus Torvalds return link_path_walk(name, nd); 10131da177e4SLinus Torvalds } 10141da177e4SLinus Torvalds 1015ea3834d9SPrasanna Meda /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1016fc9b52cdSHarvey Harrison static int do_path_lookup(int dfd, const char *name, 10175590ff0dSUlrich Drepper unsigned int flags, struct nameidata *nd) 10181da177e4SLinus Torvalds { 1019ea3834d9SPrasanna Meda int retval = 0; 1020170aa3d0SUlrich Drepper int fput_needed; 1021170aa3d0SUlrich Drepper struct file *file; 1022e518ddb7SAndreas Mohr struct fs_struct *fs = current->fs; 10231da177e4SLinus Torvalds 10241da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10251da177e4SLinus Torvalds nd->flags = flags; 10261da177e4SLinus Torvalds nd->depth = 0; 10271da177e4SLinus Torvalds 10281da177e4SLinus Torvalds if (*name=='/') { 1029e518ddb7SAndreas Mohr read_lock(&fs->lock); 10306ac08c39SJan Blunck nd->path = fs->root; 10316ac08c39SJan Blunck path_get(&fs->root); 1032e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10335590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1034e518ddb7SAndreas Mohr read_lock(&fs->lock); 10356ac08c39SJan Blunck nd->path = fs->pwd; 10366ac08c39SJan Blunck path_get(&fs->pwd); 1037e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10385590ff0dSUlrich Drepper } else { 10395590ff0dSUlrich Drepper struct dentry *dentry; 10405590ff0dSUlrich Drepper 10415590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10425590ff0dSUlrich Drepper retval = -EBADF; 1043170aa3d0SUlrich Drepper if (!file) 10446d09bb62STrond Myklebust goto out_fail; 10455590ff0dSUlrich Drepper 10460f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10475590ff0dSUlrich Drepper 10485590ff0dSUlrich Drepper retval = -ENOTDIR; 1049170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10506d09bb62STrond Myklebust goto fput_fail; 10515590ff0dSUlrich Drepper 10525590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1053170aa3d0SUlrich Drepper if (retval) 10546d09bb62STrond Myklebust goto fput_fail; 10555590ff0dSUlrich Drepper 10565dd784d0SJan Blunck nd->path = file->f_path; 10575dd784d0SJan Blunck path_get(&file->f_path); 10585590ff0dSUlrich Drepper 10595590ff0dSUlrich Drepper fput_light(file, fput_needed); 10601da177e4SLinus Torvalds } 10612dfdd266SJosef 'Jeff' Sipek 10622dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10634ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10644ac91378SJan Blunck nd->path.dentry->d_inode)) 10654ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10666d09bb62STrond Myklebust out_fail: 1067170aa3d0SUlrich Drepper return retval; 1068170aa3d0SUlrich Drepper 10696d09bb62STrond Myklebust fput_fail: 1070170aa3d0SUlrich Drepper fput_light(file, fput_needed); 10716d09bb62STrond Myklebust goto out_fail; 10721da177e4SLinus Torvalds } 10731da177e4SLinus Torvalds 1074fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 10755590ff0dSUlrich Drepper struct nameidata *nd) 10765590ff0dSUlrich Drepper { 10775590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 10785590ff0dSUlrich Drepper } 10795590ff0dSUlrich Drepper 1080d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1081d1811465SAl Viro { 1082d1811465SAl Viro struct nameidata nd; 1083d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1084d1811465SAl Viro if (!res) 1085d1811465SAl Viro *path = nd.path; 1086d1811465SAl Viro return res; 1087d1811465SAl Viro } 1088d1811465SAl Viro 108916f18200SJosef 'Jeff' Sipek /** 109016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 109116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 109216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 109316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 109416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 109516f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 109616f18200SJosef 'Jeff' Sipek */ 109716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 109816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 109916f18200SJosef 'Jeff' Sipek struct nameidata *nd) 110016f18200SJosef 'Jeff' Sipek { 110116f18200SJosef 'Jeff' Sipek int retval; 110216f18200SJosef 'Jeff' Sipek 110316f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 110416f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 110516f18200SJosef 'Jeff' Sipek nd->flags = flags; 110616f18200SJosef 'Jeff' Sipek nd->depth = 0; 110716f18200SJosef 'Jeff' Sipek 1108c8e7f449SJan Blunck nd->path.dentry = dentry; 1109c8e7f449SJan Blunck nd->path.mnt = mnt; 1110c8e7f449SJan Blunck path_get(&nd->path); 111116f18200SJosef 'Jeff' Sipek 111216f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11134ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11144ac91378SJan Blunck nd->path.dentry->d_inode)) 11154ac91378SJan Blunck audit_inode(name, nd->path.dentry); 111616f18200SJosef 'Jeff' Sipek 111716f18200SJosef 'Jeff' Sipek return retval; 111816f18200SJosef 'Jeff' Sipek 111916f18200SJosef 'Jeff' Sipek } 112016f18200SJosef 'Jeff' Sipek 1121834f2a4aSTrond Myklebust /** 1122834f2a4aSTrond Myklebust * path_lookup_open - lookup a file path with open intent 11237045f37bSMartin Waitz * @dfd: the directory to use as base, or AT_FDCWD 1124834f2a4aSTrond Myklebust * @name: pointer to file name 1125834f2a4aSTrond Myklebust * @lookup_flags: lookup intent flags 1126834f2a4aSTrond Myklebust * @nd: pointer to nameidata 1127834f2a4aSTrond Myklebust * @open_flags: open intent flags 1128834f2a4aSTrond Myklebust */ 11295590ff0dSUlrich Drepper int path_lookup_open(int dfd, const char *name, unsigned int lookup_flags, 1130834f2a4aSTrond Myklebust struct nameidata *nd, int open_flags) 1131834f2a4aSTrond Myklebust { 11328737f3a1SAl Viro struct file *filp = get_empty_filp(); 11338737f3a1SAl Viro int err; 1134834f2a4aSTrond Myklebust 11358737f3a1SAl Viro if (filp == NULL) 11368737f3a1SAl Viro return -ENFILE; 11378737f3a1SAl Viro nd->intent.open.file = filp; 11388737f3a1SAl Viro nd->intent.open.flags = open_flags; 11398737f3a1SAl Viro nd->intent.open.create_mode = 0; 11408737f3a1SAl Viro err = do_path_lookup(dfd, name, lookup_flags|LOOKUP_OPEN, nd); 11418737f3a1SAl Viro if (IS_ERR(nd->intent.open.file)) { 11428737f3a1SAl Viro if (err == 0) { 11438737f3a1SAl Viro err = PTR_ERR(nd->intent.open.file); 11448737f3a1SAl Viro path_put(&nd->path); 11458737f3a1SAl Viro } 11468737f3a1SAl Viro } else if (err != 0) 11478737f3a1SAl Viro release_open_intent(nd); 11488737f3a1SAl Viro return err; 1149834f2a4aSTrond Myklebust } 1150834f2a4aSTrond Myklebust 1151eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1152eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 11531da177e4SLinus Torvalds { 11541da177e4SLinus Torvalds struct dentry *dentry; 11551da177e4SLinus Torvalds struct inode *inode; 11561da177e4SLinus Torvalds int err; 11571da177e4SLinus Torvalds 11581da177e4SLinus Torvalds inode = base->d_inode; 11591da177e4SLinus Torvalds 11601da177e4SLinus Torvalds /* 11611da177e4SLinus Torvalds * See if the low-level filesystem might want 11621da177e4SLinus Torvalds * to use its own hash.. 11631da177e4SLinus Torvalds */ 11641da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 11651da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 11661da177e4SLinus Torvalds dentry = ERR_PTR(err); 11671da177e4SLinus Torvalds if (err < 0) 11681da177e4SLinus Torvalds goto out; 11691da177e4SLinus Torvalds } 11701da177e4SLinus Torvalds 11711da177e4SLinus Torvalds dentry = cached_lookup(base, name, nd); 11721da177e4SLinus Torvalds if (!dentry) { 1173d70b67c8SMiklos Szeredi struct dentry *new; 1174d70b67c8SMiklos Szeredi 1175d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1176d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1177d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1178d70b67c8SMiklos Szeredi goto out; 1179d70b67c8SMiklos Szeredi 1180d70b67c8SMiklos Szeredi new = d_alloc(base, name); 11811da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 11821da177e4SLinus Torvalds if (!new) 11831da177e4SLinus Torvalds goto out; 11841da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 11851da177e4SLinus Torvalds if (!dentry) 11861da177e4SLinus Torvalds dentry = new; 11871da177e4SLinus Torvalds else 11881da177e4SLinus Torvalds dput(new); 11891da177e4SLinus Torvalds } 11901da177e4SLinus Torvalds out: 11911da177e4SLinus Torvalds return dentry; 11921da177e4SLinus Torvalds } 11931da177e4SLinus Torvalds 1194057f6c01SJames Morris /* 1195057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1196057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1197057f6c01SJames Morris * SMP-safe. 1198057f6c01SJames Morris */ 1199a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 12001da177e4SLinus Torvalds { 1201eead1911SChristoph Hellwig int err; 1202eead1911SChristoph Hellwig 1203f419a2e3SAl Viro err = inode_permission(nd->path.dentry->d_inode, MAY_EXEC); 1204eead1911SChristoph Hellwig if (err) 1205eead1911SChristoph Hellwig return ERR_PTR(err); 12064ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 12071da177e4SLinus Torvalds } 12081da177e4SLinus Torvalds 1209eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1210eead1911SChristoph Hellwig struct dentry *base, int len) 12111da177e4SLinus Torvalds { 12121da177e4SLinus Torvalds unsigned long hash; 12131da177e4SLinus Torvalds unsigned int c; 12141da177e4SLinus Torvalds 1215057f6c01SJames Morris this->name = name; 1216057f6c01SJames Morris this->len = len; 12171da177e4SLinus Torvalds if (!len) 1218057f6c01SJames Morris return -EACCES; 12191da177e4SLinus Torvalds 12201da177e4SLinus Torvalds hash = init_name_hash(); 12211da177e4SLinus Torvalds while (len--) { 12221da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12231da177e4SLinus Torvalds if (c == '/' || c == '\0') 1224057f6c01SJames Morris return -EACCES; 12251da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12261da177e4SLinus Torvalds } 1227057f6c01SJames Morris this->hash = end_name_hash(hash); 1228057f6c01SJames Morris return 0; 1229057f6c01SJames Morris } 12301da177e4SLinus Torvalds 1231eead1911SChristoph Hellwig /** 1232a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1233eead1911SChristoph Hellwig * @name: pathname component to lookup 1234eead1911SChristoph Hellwig * @base: base directory to lookup from 1235eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1236eead1911SChristoph Hellwig * 1237a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1238a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1239eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1240eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1241eead1911SChristoph Hellwig */ 1242057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1243057f6c01SJames Morris { 1244057f6c01SJames Morris int err; 1245057f6c01SJames Morris struct qstr this; 1246057f6c01SJames Morris 1247057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1248057f6c01SJames Morris if (err) 1249057f6c01SJames Morris return ERR_PTR(err); 1250eead1911SChristoph Hellwig 1251f419a2e3SAl Viro err = inode_permission(base->d_inode, MAY_EXEC); 1252eead1911SChristoph Hellwig if (err) 1253eead1911SChristoph Hellwig return ERR_PTR(err); 125449705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1255057f6c01SJames Morris } 1256057f6c01SJames Morris 1257eead1911SChristoph Hellwig /** 1258eead1911SChristoph Hellwig * lookup_one_noperm - bad hack for sysfs 1259eead1911SChristoph Hellwig * @name: pathname component to lookup 1260eead1911SChristoph Hellwig * @base: base directory to lookup from 1261eead1911SChristoph Hellwig * 1262eead1911SChristoph Hellwig * This is a variant of lookup_one_len that doesn't perform any permission 1263eead1911SChristoph Hellwig * checks. It's a horrible hack to work around the braindead sysfs 1264eead1911SChristoph Hellwig * architecture and should not be used anywhere else. 1265eead1911SChristoph Hellwig * 1266eead1911SChristoph Hellwig * DON'T USE THIS FUNCTION EVER, thanks. 1267eead1911SChristoph Hellwig */ 1268eead1911SChristoph Hellwig struct dentry *lookup_one_noperm(const char *name, struct dentry *base) 1269057f6c01SJames Morris { 1270057f6c01SJames Morris int err; 1271057f6c01SJames Morris struct qstr this; 1272057f6c01SJames Morris 1273eead1911SChristoph Hellwig err = __lookup_one_len(name, &this, base, strlen(name)); 1274057f6c01SJames Morris if (err) 1275057f6c01SJames Morris return ERR_PTR(err); 1276eead1911SChristoph Hellwig return __lookup_hash(&this, base, NULL); 12771da177e4SLinus Torvalds } 12781da177e4SLinus Torvalds 12792d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 12802d8f3038SAl Viro struct path *path) 12811da177e4SLinus Torvalds { 12822d8f3038SAl Viro struct nameidata nd; 12831da177e4SLinus Torvalds char *tmp = getname(name); 12841da177e4SLinus Torvalds int err = PTR_ERR(tmp); 12851da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 12862d8f3038SAl Viro 12872d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 12882d8f3038SAl Viro 12892d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 12901da177e4SLinus Torvalds putname(tmp); 12912d8f3038SAl Viro if (!err) 12922d8f3038SAl Viro *path = nd.path; 12931da177e4SLinus Torvalds } 12941da177e4SLinus Torvalds return err; 12951da177e4SLinus Torvalds } 12961da177e4SLinus Torvalds 12972ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 12982ad94ae6SAl Viro struct nameidata *nd, char **name) 12992ad94ae6SAl Viro { 13002ad94ae6SAl Viro char *s = getname(path); 13012ad94ae6SAl Viro int error; 13022ad94ae6SAl Viro 13032ad94ae6SAl Viro if (IS_ERR(s)) 13042ad94ae6SAl Viro return PTR_ERR(s); 13052ad94ae6SAl Viro 13062ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 13072ad94ae6SAl Viro if (error) 13082ad94ae6SAl Viro putname(s); 13092ad94ae6SAl Viro else 13102ad94ae6SAl Viro *name = s; 13112ad94ae6SAl Viro 13122ad94ae6SAl Viro return error; 13132ad94ae6SAl Viro } 13142ad94ae6SAl Viro 13151da177e4SLinus Torvalds /* 13161da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 13171da177e4SLinus Torvalds * minimal. 13181da177e4SLinus Torvalds */ 13191da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 13201da177e4SLinus Torvalds { 1321da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1322da9592edSDavid Howells 13231da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 13241da177e4SLinus Torvalds return 0; 1325da9592edSDavid Howells if (inode->i_uid == fsuid) 13261da177e4SLinus Torvalds return 0; 1327da9592edSDavid Howells if (dir->i_uid == fsuid) 13281da177e4SLinus Torvalds return 0; 13291da177e4SLinus Torvalds return !capable(CAP_FOWNER); 13301da177e4SLinus Torvalds } 13311da177e4SLinus Torvalds 13321da177e4SLinus Torvalds /* 13331da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 13341da177e4SLinus Torvalds * whether the type of victim is right. 13351da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 13361da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 13371da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 13381da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13391da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13401da177e4SLinus Torvalds * a. be owner of dir, or 13411da177e4SLinus Torvalds * b. be owner of victim, or 13421da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13431da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 13441da177e4SLinus Torvalds * links pointing to it. 13451da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 13461da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 13471da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 13481da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 13491da177e4SLinus Torvalds * nfs_async_unlink(). 13501da177e4SLinus Torvalds */ 1351858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 13521da177e4SLinus Torvalds { 13531da177e4SLinus Torvalds int error; 13541da177e4SLinus Torvalds 13551da177e4SLinus Torvalds if (!victim->d_inode) 13561da177e4SLinus Torvalds return -ENOENT; 13571da177e4SLinus Torvalds 13581da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 13595a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 13601da177e4SLinus Torvalds 1361f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 13621da177e4SLinus Torvalds if (error) 13631da177e4SLinus Torvalds return error; 13641da177e4SLinus Torvalds if (IS_APPEND(dir)) 13651da177e4SLinus Torvalds return -EPERM; 13661da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1367f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 13681da177e4SLinus Torvalds return -EPERM; 13691da177e4SLinus Torvalds if (isdir) { 13701da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 13711da177e4SLinus Torvalds return -ENOTDIR; 13721da177e4SLinus Torvalds if (IS_ROOT(victim)) 13731da177e4SLinus Torvalds return -EBUSY; 13741da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 13751da177e4SLinus Torvalds return -EISDIR; 13761da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13771da177e4SLinus Torvalds return -ENOENT; 13781da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 13791da177e4SLinus Torvalds return -EBUSY; 13801da177e4SLinus Torvalds return 0; 13811da177e4SLinus Torvalds } 13821da177e4SLinus Torvalds 13831da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 13841da177e4SLinus Torvalds * dir. 13851da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 13861da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 13871da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 13881da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 13891da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 13901da177e4SLinus Torvalds */ 1391a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 13921da177e4SLinus Torvalds { 13931da177e4SLinus Torvalds if (child->d_inode) 13941da177e4SLinus Torvalds return -EEXIST; 13951da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13961da177e4SLinus Torvalds return -ENOENT; 1397f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 13981da177e4SLinus Torvalds } 13991da177e4SLinus Torvalds 14001da177e4SLinus Torvalds /* 14011da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 14021da177e4SLinus Torvalds */ 14031da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 14041da177e4SLinus Torvalds { 14051da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 14061da177e4SLinus Torvalds 14071da177e4SLinus Torvalds if (f & O_NOFOLLOW) 14081da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 14091da177e4SLinus Torvalds 14101da177e4SLinus Torvalds if (f & O_DIRECTORY) 14111da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 14121da177e4SLinus Torvalds 14131da177e4SLinus Torvalds return retval; 14141da177e4SLinus Torvalds } 14151da177e4SLinus Torvalds 14161da177e4SLinus Torvalds /* 14171da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 14181da177e4SLinus Torvalds */ 14191da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 14201da177e4SLinus Torvalds { 14211da177e4SLinus Torvalds struct dentry *p; 14221da177e4SLinus Torvalds 14231da177e4SLinus Torvalds if (p1 == p2) { 1424f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 14251da177e4SLinus Torvalds return NULL; 14261da177e4SLinus Torvalds } 14271da177e4SLinus Torvalds 1428a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14291da177e4SLinus Torvalds 1430e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1431e2761a11SOGAWA Hirofumi if (p) { 1432f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1433f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 14341da177e4SLinus Torvalds return p; 14351da177e4SLinus Torvalds } 14361da177e4SLinus Torvalds 1437e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1438e2761a11SOGAWA Hirofumi if (p) { 1439f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1440f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14411da177e4SLinus Torvalds return p; 14421da177e4SLinus Torvalds } 14431da177e4SLinus Torvalds 1444f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1445f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14461da177e4SLinus Torvalds return NULL; 14471da177e4SLinus Torvalds } 14481da177e4SLinus Torvalds 14491da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 14501da177e4SLinus Torvalds { 14511b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 14521da177e4SLinus Torvalds if (p1 != p2) { 14531b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1454a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14551da177e4SLinus Torvalds } 14561da177e4SLinus Torvalds } 14571da177e4SLinus Torvalds 14581da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 14591da177e4SLinus Torvalds struct nameidata *nd) 14601da177e4SLinus Torvalds { 1461a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 14621da177e4SLinus Torvalds 14631da177e4SLinus Torvalds if (error) 14641da177e4SLinus Torvalds return error; 14651da177e4SLinus Torvalds 1466acfa4380SAl Viro if (!dir->i_op->create) 14671da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 14681da177e4SLinus Torvalds mode &= S_IALLUGO; 14691da177e4SLinus Torvalds mode |= S_IFREG; 14701da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 14711da177e4SLinus Torvalds if (error) 14721da177e4SLinus Torvalds return error; 14731da177e4SLinus Torvalds DQUOT_INIT(dir); 14741da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1475a74574aaSStephen Smalley if (!error) 1476f38aa942SAmy Griffis fsnotify_create(dir, dentry); 14771da177e4SLinus Torvalds return error; 14781da177e4SLinus Torvalds } 14791da177e4SLinus Torvalds 14803fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 14811da177e4SLinus Torvalds { 14823fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 14831da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 14841da177e4SLinus Torvalds int error; 14851da177e4SLinus Torvalds 14861da177e4SLinus Torvalds if (!inode) 14871da177e4SLinus Torvalds return -ENOENT; 14881da177e4SLinus Torvalds 14891da177e4SLinus Torvalds if (S_ISLNK(inode->i_mode)) 14901da177e4SLinus Torvalds return -ELOOP; 14911da177e4SLinus Torvalds 1492974a9f0bSLinus Torvalds if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) 14931da177e4SLinus Torvalds return -EISDIR; 14941da177e4SLinus Torvalds 14951da177e4SLinus Torvalds /* 14961da177e4SLinus Torvalds * FIFO's, sockets and device files are special: they don't 14971da177e4SLinus Torvalds * actually live on the filesystem itself, and as such you 14981da177e4SLinus Torvalds * can write to them even if the filesystem is read-only. 14991da177e4SLinus Torvalds */ 15001da177e4SLinus Torvalds if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 15011da177e4SLinus Torvalds flag &= ~O_TRUNC; 15021da177e4SLinus Torvalds } else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) { 15033fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 15041da177e4SLinus Torvalds return -EACCES; 15051da177e4SLinus Torvalds 15061da177e4SLinus Torvalds flag &= ~O_TRUNC; 15074a3fd211SDave Hansen } 1508b41572e9SDave Hansen 15093fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1510b41572e9SDave Hansen if (error) 1511b41572e9SDave Hansen return error; 15121da177e4SLinus Torvalds /* 15131da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 15141da177e4SLinus Torvalds */ 15151da177e4SLinus Torvalds if (IS_APPEND(inode)) { 15161da177e4SLinus Torvalds if ((flag & FMODE_WRITE) && !(flag & O_APPEND)) 15171da177e4SLinus Torvalds return -EPERM; 15181da177e4SLinus Torvalds if (flag & O_TRUNC) 15191da177e4SLinus Torvalds return -EPERM; 15201da177e4SLinus Torvalds } 15211da177e4SLinus Torvalds 15221da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15231da177e4SLinus Torvalds if (flag & O_NOATIME) 15243bd858abSSatyam Sharma if (!is_owner_or_cap(inode)) 15251da177e4SLinus Torvalds return -EPERM; 15261da177e4SLinus Torvalds 15271da177e4SLinus Torvalds /* 15281da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15291da177e4SLinus Torvalds */ 15301da177e4SLinus Torvalds error = break_lease(inode, flag); 15311da177e4SLinus Torvalds if (error) 15321da177e4SLinus Torvalds return error; 15331da177e4SLinus Torvalds 15341da177e4SLinus Torvalds if (flag & O_TRUNC) { 15351da177e4SLinus Torvalds error = get_write_access(inode); 15361da177e4SLinus Torvalds if (error) 15371da177e4SLinus Torvalds return error; 15381da177e4SLinus Torvalds 15391da177e4SLinus Torvalds /* 15401da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 15411da177e4SLinus Torvalds */ 15421da177e4SLinus Torvalds error = locks_verify_locked(inode); 1543be6d3e56SKentaro Takeda if (!error) 15443fb64190SChristoph Hellwig error = security_path_truncate(path, 0, 1545be6d3e56SKentaro Takeda ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); 15461da177e4SLinus Torvalds if (!error) { 15471da177e4SLinus Torvalds DQUOT_INIT(inode); 15481da177e4SLinus Torvalds 1549d139d7ffSMiklos Szeredi error = do_truncate(dentry, 0, 1550d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1551d139d7ffSMiklos Szeredi NULL); 15521da177e4SLinus Torvalds } 15531da177e4SLinus Torvalds put_write_access(inode); 15541da177e4SLinus Torvalds if (error) 15551da177e4SLinus Torvalds return error; 15561da177e4SLinus Torvalds } else 15571da177e4SLinus Torvalds if (flag & FMODE_WRITE) 15581da177e4SLinus Torvalds DQUOT_INIT(inode); 15591da177e4SLinus Torvalds 15601da177e4SLinus Torvalds return 0; 15611da177e4SLinus Torvalds } 15621da177e4SLinus Torvalds 1563d57999e1SDave Hansen /* 1564d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1565d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1566d57999e1SDave Hansen * what get passed to sys_open(). 1567d57999e1SDave Hansen */ 1568d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 1569aab520e2SDave Hansen int flag, int mode) 1570aab520e2SDave Hansen { 1571aab520e2SDave Hansen int error; 15724ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1573aab520e2SDave Hansen 1574aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1575aab520e2SDave Hansen mode &= ~current->fs->umask; 1576be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1577be6d3e56SKentaro Takeda if (error) 1578be6d3e56SKentaro Takeda goto out_unlock; 1579aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1580be6d3e56SKentaro Takeda out_unlock: 1581aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 15824ac91378SJan Blunck dput(nd->path.dentry); 15834ac91378SJan Blunck nd->path.dentry = path->dentry; 1584aab520e2SDave Hansen if (error) 1585aab520e2SDave Hansen return error; 1586aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 15873fb64190SChristoph Hellwig return may_open(&nd->path, 0, flag & ~O_TRUNC); 1588aab520e2SDave Hansen } 1589aab520e2SDave Hansen 15901da177e4SLinus Torvalds /* 1591d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1592d57999e1SDave Hansen * 00 - read-only 1593d57999e1SDave Hansen * 01 - write-only 1594d57999e1SDave Hansen * 10 - read-write 1595d57999e1SDave Hansen * 11 - special 1596d57999e1SDave Hansen * it is changed into 1597d57999e1SDave Hansen * 00 - no permissions needed 1598d57999e1SDave Hansen * 01 - read-permission 1599d57999e1SDave Hansen * 10 - write-permission 1600d57999e1SDave Hansen * 11 - read-write 1601d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1602d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1603d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1604d57999e1SDave Hansen * later). 1605d57999e1SDave Hansen * 1606d57999e1SDave Hansen */ 1607d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1608d57999e1SDave Hansen { 1609d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1610d57999e1SDave Hansen flag++; 1611d57999e1SDave Hansen return flag; 1612d57999e1SDave Hansen } 1613d57999e1SDave Hansen 16144a3fd211SDave Hansen static int open_will_write_to_fs(int flag, struct inode *inode) 16154a3fd211SDave Hansen { 1616d57999e1SDave Hansen /* 16174a3fd211SDave Hansen * We'll never write to the fs underlying 16184a3fd211SDave Hansen * a device file. 16194a3fd211SDave Hansen */ 16204a3fd211SDave Hansen if (special_file(inode->i_mode)) 16214a3fd211SDave Hansen return 0; 16224a3fd211SDave Hansen return (flag & O_TRUNC); 16234a3fd211SDave Hansen } 16244a3fd211SDave Hansen 16254a3fd211SDave Hansen /* 16264a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16274a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16284a3fd211SDave Hansen * open_to_namei_flags() for more details. 16291da177e4SLinus Torvalds */ 1630a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 1631a70e65dfSChristoph Hellwig int open_flag, int mode) 16321da177e4SLinus Torvalds { 16334a3fd211SDave Hansen struct file *filp; 1634a70e65dfSChristoph Hellwig struct nameidata nd; 1635834f2a4aSTrond Myklebust int acc_mode, error; 16364e7506e4SAl Viro struct path path; 16371da177e4SLinus Torvalds struct dentry *dir; 16381da177e4SLinus Torvalds int count = 0; 16394a3fd211SDave Hansen int will_write; 1640d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16411da177e4SLinus Torvalds 1642b77b0646SAl Viro acc_mode = MAY_OPEN | ACC_MODE(flag); 16431da177e4SLinus Torvalds 1644834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1645834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1646834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1647834f2a4aSTrond Myklebust 16481da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 16491da177e4SLinus Torvalds access from general write access. */ 16501da177e4SLinus Torvalds if (flag & O_APPEND) 16511da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 16521da177e4SLinus Torvalds 16531da177e4SLinus Torvalds /* 16541da177e4SLinus Torvalds * The simplest case - just a plain lookup. 16551da177e4SLinus Torvalds */ 16561da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 16575590ff0dSUlrich Drepper error = path_lookup_open(dfd, pathname, lookup_flags(flag), 1658a70e65dfSChristoph Hellwig &nd, flag); 16591da177e4SLinus Torvalds if (error) 1660a70e65dfSChristoph Hellwig return ERR_PTR(error); 16611da177e4SLinus Torvalds goto ok; 16621da177e4SLinus Torvalds } 16631da177e4SLinus Torvalds 16641da177e4SLinus Torvalds /* 16651da177e4SLinus Torvalds * Create - we need to know the parent. 16661da177e4SLinus Torvalds */ 16678737f3a1SAl Viro error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 16681da177e4SLinus Torvalds if (error) 1669a70e65dfSChristoph Hellwig return ERR_PTR(error); 16701da177e4SLinus Torvalds 16711da177e4SLinus Torvalds /* 16721da177e4SLinus Torvalds * We have the parent and last component. First of all, check 16731da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 16741da177e4SLinus Torvalds * will not do. 16751da177e4SLinus Torvalds */ 16761da177e4SLinus Torvalds error = -EISDIR; 1677a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 16788737f3a1SAl Viro goto exit_parent; 16791da177e4SLinus Torvalds 16808737f3a1SAl Viro error = -ENFILE; 16818737f3a1SAl Viro filp = get_empty_filp(); 16828737f3a1SAl Viro if (filp == NULL) 16838737f3a1SAl Viro goto exit_parent; 16848737f3a1SAl Viro nd.intent.open.file = filp; 16858737f3a1SAl Viro nd.intent.open.flags = flag; 16868737f3a1SAl Viro nd.intent.open.create_mode = mode; 1687a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1688a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 16898737f3a1SAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; 16903516586aSAl Viro if (flag & O_EXCL) 16913516586aSAl Viro nd.flags |= LOOKUP_EXCL; 16921b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1693a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1694a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 16951da177e4SLinus Torvalds 16961da177e4SLinus Torvalds do_last: 16974e7506e4SAl Viro error = PTR_ERR(path.dentry); 16984e7506e4SAl Viro if (IS_ERR(path.dentry)) { 16991b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17001da177e4SLinus Torvalds goto exit; 17011da177e4SLinus Torvalds } 17021da177e4SLinus Torvalds 1703a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1704a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17054a3fd211SDave Hansen goto exit_mutex_unlock; 17064af4c52fSOleg Drokin } 17074af4c52fSOleg Drokin 17081da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17094e7506e4SAl Viro if (!path.dentry->d_inode) { 17104a3fd211SDave Hansen /* 17114a3fd211SDave Hansen * This write is needed to ensure that a 17124a3fd211SDave Hansen * ro->rw transition does not occur between 17134a3fd211SDave Hansen * the time when the file is created and when 17144a3fd211SDave Hansen * a permanent write count is taken through 17154a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17164a3fd211SDave Hansen */ 17174a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17181da177e4SLinus Torvalds if (error) 17194a3fd211SDave Hansen goto exit_mutex_unlock; 17204a3fd211SDave Hansen error = __open_namei_create(&nd, &path, flag, mode); 17214a3fd211SDave Hansen if (error) { 17224a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17231da177e4SLinus Torvalds goto exit; 17244a3fd211SDave Hansen } 17254a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17264a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17274a3fd211SDave Hansen return filp; 17281da177e4SLinus Torvalds } 17291da177e4SLinus Torvalds 17301da177e4SLinus Torvalds /* 17311da177e4SLinus Torvalds * It already exists. 17321da177e4SLinus Torvalds */ 17331b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17345a190ae6SAl Viro audit_inode(pathname, path.dentry); 17351da177e4SLinus Torvalds 17361da177e4SLinus Torvalds error = -EEXIST; 17371da177e4SLinus Torvalds if (flag & O_EXCL) 17381da177e4SLinus Torvalds goto exit_dput; 17391da177e4SLinus Torvalds 1740e13b210fSAl Viro if (__follow_mount(&path)) { 17411da177e4SLinus Torvalds error = -ELOOP; 1742ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1743ba7a4c1aSAl Viro goto exit_dput; 17441da177e4SLinus Torvalds } 17453e2efce0SAmy Griffis 17461da177e4SLinus Torvalds error = -ENOENT; 17474e7506e4SAl Viro if (!path.dentry->d_inode) 17481da177e4SLinus Torvalds goto exit_dput; 1749acfa4380SAl Viro if (path.dentry->d_inode->i_op->follow_link) 17501da177e4SLinus Torvalds goto do_link; 17511da177e4SLinus Torvalds 1752a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 17531da177e4SLinus Torvalds error = -EISDIR; 17544e7506e4SAl Viro if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode)) 17551da177e4SLinus Torvalds goto exit; 17561da177e4SLinus Torvalds ok: 17574a3fd211SDave Hansen /* 17584a3fd211SDave Hansen * Consider: 17594a3fd211SDave Hansen * 1. may_open() truncates a file 17604a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 17614a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 17624a3fd211SDave Hansen * the ro mount. 17634a3fd211SDave Hansen * That would be inconsistent, and should 17644a3fd211SDave Hansen * be avoided. Taking this mnt write here 17654a3fd211SDave Hansen * ensures that (2) can not occur. 17664a3fd211SDave Hansen */ 17674a3fd211SDave Hansen will_write = open_will_write_to_fs(flag, nd.path.dentry->d_inode); 17684a3fd211SDave Hansen if (will_write) { 17694a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17701da177e4SLinus Torvalds if (error) 17711da177e4SLinus Torvalds goto exit; 17724a3fd211SDave Hansen } 17733fb64190SChristoph Hellwig error = may_open(&nd.path, acc_mode, flag); 17744a3fd211SDave Hansen if (error) { 17754a3fd211SDave Hansen if (will_write) 17764a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17774a3fd211SDave Hansen goto exit; 17784a3fd211SDave Hansen } 17794a3fd211SDave Hansen filp = nameidata_to_filp(&nd, open_flag); 17804a3fd211SDave Hansen /* 17814a3fd211SDave Hansen * It is now safe to drop the mnt write 17824a3fd211SDave Hansen * because the filp has had a write taken 17834a3fd211SDave Hansen * on its behalf. 17844a3fd211SDave Hansen */ 17854a3fd211SDave Hansen if (will_write) 17864a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17874a3fd211SDave Hansen return filp; 17881da177e4SLinus Torvalds 17894a3fd211SDave Hansen exit_mutex_unlock: 17904a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 17911da177e4SLinus Torvalds exit_dput: 1792a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 17931da177e4SLinus Torvalds exit: 1794a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1795a70e65dfSChristoph Hellwig release_open_intent(&nd); 17968737f3a1SAl Viro exit_parent: 1797a70e65dfSChristoph Hellwig path_put(&nd.path); 1798a70e65dfSChristoph Hellwig return ERR_PTR(error); 17991da177e4SLinus Torvalds 18001da177e4SLinus Torvalds do_link: 18011da177e4SLinus Torvalds error = -ELOOP; 18021da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18031da177e4SLinus Torvalds goto exit_dput; 18041da177e4SLinus Torvalds /* 18051da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18061da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18071da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18081da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18091da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18101da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18111da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18121da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18131da177e4SLinus Torvalds */ 1814a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1815a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18161da177e4SLinus Torvalds if (error) 18171da177e4SLinus Torvalds goto exit_dput; 1818a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1819de459215SKirill Korotaev if (error) { 1820de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1821de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1822de459215SKirill Korotaev * with "intent.open". 1823de459215SKirill Korotaev */ 1824a70e65dfSChristoph Hellwig release_open_intent(&nd); 1825a70e65dfSChristoph Hellwig return ERR_PTR(error); 1826de459215SKirill Korotaev } 1827a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1828a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18291da177e4SLinus Torvalds goto ok; 18301da177e4SLinus Torvalds error = -EISDIR; 1831a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18321da177e4SLinus Torvalds goto exit; 1833a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1834a70e65dfSChristoph Hellwig __putname(nd.last.name); 18351da177e4SLinus Torvalds goto exit; 18361da177e4SLinus Torvalds } 18371da177e4SLinus Torvalds error = -ELOOP; 18381da177e4SLinus Torvalds if (count++==32) { 1839a70e65dfSChristoph Hellwig __putname(nd.last.name); 18401da177e4SLinus Torvalds goto exit; 18411da177e4SLinus Torvalds } 1842a70e65dfSChristoph Hellwig dir = nd.path.dentry; 18431b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1844a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1845a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1846a70e65dfSChristoph Hellwig __putname(nd.last.name); 18471da177e4SLinus Torvalds goto do_last; 18481da177e4SLinus Torvalds } 18491da177e4SLinus Torvalds 18501da177e4SLinus Torvalds /** 1851a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1852a70e65dfSChristoph Hellwig * 1853a70e65dfSChristoph Hellwig * @filename: path to open 1854a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1855a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1856a70e65dfSChristoph Hellwig * 1857a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1858a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1859a70e65dfSChristoph Hellwig * along, nothing to see here.. 1860a70e65dfSChristoph Hellwig */ 1861a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1862a70e65dfSChristoph Hellwig { 1863a70e65dfSChristoph Hellwig return do_filp_open(AT_FDCWD, filename, flags, mode); 1864a70e65dfSChristoph Hellwig } 1865a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1866a70e65dfSChristoph Hellwig 1867a70e65dfSChristoph Hellwig /** 18681da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 18691da177e4SLinus Torvalds * @nd: nameidata info 18701da177e4SLinus Torvalds * @is_dir: directory flag 18711da177e4SLinus Torvalds * 18721da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 18731da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1874c663e5d8SChristoph Hellwig * 18754ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 18761da177e4SLinus Torvalds */ 18771da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 18781da177e4SLinus Torvalds { 1879c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 18801da177e4SLinus Torvalds 18814ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1882c663e5d8SChristoph Hellwig /* 1883c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1884c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1885c663e5d8SChristoph Hellwig */ 18861da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 18871da177e4SLinus Torvalds goto fail; 18881da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 18893516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1890a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1891c663e5d8SChristoph Hellwig 1892c663e5d8SChristoph Hellwig /* 1893c663e5d8SChristoph Hellwig * Do the final lookup. 1894c663e5d8SChristoph Hellwig */ 189549705b77SChristoph Hellwig dentry = lookup_hash(nd); 18961da177e4SLinus Torvalds if (IS_ERR(dentry)) 18971da177e4SLinus Torvalds goto fail; 1898c663e5d8SChristoph Hellwig 1899e9baf6e5SAl Viro if (dentry->d_inode) 1900e9baf6e5SAl Viro goto eexist; 1901c663e5d8SChristoph Hellwig /* 1902c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1903c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1904c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1905c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1906c663e5d8SChristoph Hellwig */ 1907e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19081da177e4SLinus Torvalds dput(dentry); 19091da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1910e9baf6e5SAl Viro } 1911e9baf6e5SAl Viro return dentry; 1912e9baf6e5SAl Viro eexist: 1913e9baf6e5SAl Viro dput(dentry); 1914e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19151da177e4SLinus Torvalds fail: 19161da177e4SLinus Torvalds return dentry; 19171da177e4SLinus Torvalds } 1918f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19191da177e4SLinus Torvalds 19201da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19211da177e4SLinus Torvalds { 1922a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19231da177e4SLinus Torvalds 19241da177e4SLinus Torvalds if (error) 19251da177e4SLinus Torvalds return error; 19261da177e4SLinus Torvalds 19271da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19281da177e4SLinus Torvalds return -EPERM; 19291da177e4SLinus Torvalds 1930acfa4380SAl Viro if (!dir->i_op->mknod) 19311da177e4SLinus Torvalds return -EPERM; 19321da177e4SLinus Torvalds 193308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 193408ce5f16SSerge E. Hallyn if (error) 193508ce5f16SSerge E. Hallyn return error; 193608ce5f16SSerge E. Hallyn 19371da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19381da177e4SLinus Torvalds if (error) 19391da177e4SLinus Torvalds return error; 19401da177e4SLinus Torvalds 19411da177e4SLinus Torvalds DQUOT_INIT(dir); 19421da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1943a74574aaSStephen Smalley if (!error) 1944f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19451da177e4SLinus Torvalds return error; 19461da177e4SLinus Torvalds } 19471da177e4SLinus Torvalds 1948463c3197SDave Hansen static int may_mknod(mode_t mode) 1949463c3197SDave Hansen { 1950463c3197SDave Hansen switch (mode & S_IFMT) { 1951463c3197SDave Hansen case S_IFREG: 1952463c3197SDave Hansen case S_IFCHR: 1953463c3197SDave Hansen case S_IFBLK: 1954463c3197SDave Hansen case S_IFIFO: 1955463c3197SDave Hansen case S_IFSOCK: 1956463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 1957463c3197SDave Hansen return 0; 1958463c3197SDave Hansen case S_IFDIR: 1959463c3197SDave Hansen return -EPERM; 1960463c3197SDave Hansen default: 1961463c3197SDave Hansen return -EINVAL; 1962463c3197SDave Hansen } 1963463c3197SDave Hansen } 1964463c3197SDave Hansen 19655590ff0dSUlrich Drepper asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode, 19665590ff0dSUlrich Drepper unsigned dev) 19671da177e4SLinus Torvalds { 19682ad94ae6SAl Viro int error; 19691da177e4SLinus Torvalds char *tmp; 19701da177e4SLinus Torvalds struct dentry *dentry; 19711da177e4SLinus Torvalds struct nameidata nd; 19721da177e4SLinus Torvalds 19731da177e4SLinus Torvalds if (S_ISDIR(mode)) 19741da177e4SLinus Torvalds return -EPERM; 19751da177e4SLinus Torvalds 19762ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 19771da177e4SLinus Torvalds if (error) 19782ad94ae6SAl Viro return error; 19792ad94ae6SAl Viro 19801da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 1981463c3197SDave Hansen if (IS_ERR(dentry)) { 19821da177e4SLinus Torvalds error = PTR_ERR(dentry); 1983463c3197SDave Hansen goto out_unlock; 1984463c3197SDave Hansen } 19854ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 19861da177e4SLinus Torvalds mode &= ~current->fs->umask; 1987463c3197SDave Hansen error = may_mknod(mode); 1988463c3197SDave Hansen if (error) 1989463c3197SDave Hansen goto out_dput; 1990463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 1991463c3197SDave Hansen if (error) 1992463c3197SDave Hansen goto out_dput; 1993be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 1994be6d3e56SKentaro Takeda if (error) 1995be6d3e56SKentaro Takeda goto out_drop_write; 19961da177e4SLinus Torvalds switch (mode & S_IFMT) { 19971da177e4SLinus Torvalds case 0: case S_IFREG: 19984ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 19991da177e4SLinus Torvalds break; 20001da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20014ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20021da177e4SLinus Torvalds new_decode_dev(dev)); 20031da177e4SLinus Torvalds break; 20041da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20054ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20061da177e4SLinus Torvalds break; 20071da177e4SLinus Torvalds } 2008be6d3e56SKentaro Takeda out_drop_write: 2009463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2010463c3197SDave Hansen out_dput: 20111da177e4SLinus Torvalds dput(dentry); 2012463c3197SDave Hansen out_unlock: 20134ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20141d957f9bSJan Blunck path_put(&nd.path); 20151da177e4SLinus Torvalds putname(tmp); 20161da177e4SLinus Torvalds 20171da177e4SLinus Torvalds return error; 20181da177e4SLinus Torvalds } 20191da177e4SLinus Torvalds 20205590ff0dSUlrich Drepper asmlinkage long sys_mknod(const char __user *filename, int mode, unsigned dev) 20215590ff0dSUlrich Drepper { 20225590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20235590ff0dSUlrich Drepper } 20245590ff0dSUlrich Drepper 20251da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20261da177e4SLinus Torvalds { 2027a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20281da177e4SLinus Torvalds 20291da177e4SLinus Torvalds if (error) 20301da177e4SLinus Torvalds return error; 20311da177e4SLinus Torvalds 2032acfa4380SAl Viro if (!dir->i_op->mkdir) 20331da177e4SLinus Torvalds return -EPERM; 20341da177e4SLinus Torvalds 20351da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20361da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20371da177e4SLinus Torvalds if (error) 20381da177e4SLinus Torvalds return error; 20391da177e4SLinus Torvalds 20401da177e4SLinus Torvalds DQUOT_INIT(dir); 20411da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2042a74574aaSStephen Smalley if (!error) 2043f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20441da177e4SLinus Torvalds return error; 20451da177e4SLinus Torvalds } 20461da177e4SLinus Torvalds 20475590ff0dSUlrich Drepper asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode) 20481da177e4SLinus Torvalds { 20491da177e4SLinus Torvalds int error = 0; 20501da177e4SLinus Torvalds char * tmp; 20516902d925SDave Hansen struct dentry *dentry; 20526902d925SDave Hansen struct nameidata nd; 20531da177e4SLinus Torvalds 20542ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 20552ad94ae6SAl Viro if (error) 20566902d925SDave Hansen goto out_err; 20571da177e4SLinus Torvalds 20581da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 20591da177e4SLinus Torvalds error = PTR_ERR(dentry); 20606902d925SDave Hansen if (IS_ERR(dentry)) 20616902d925SDave Hansen goto out_unlock; 20626902d925SDave Hansen 20634ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 20641da177e4SLinus Torvalds mode &= ~current->fs->umask; 2065463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2066463c3197SDave Hansen if (error) 2067463c3197SDave Hansen goto out_dput; 2068be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2069be6d3e56SKentaro Takeda if (error) 2070be6d3e56SKentaro Takeda goto out_drop_write; 20714ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2072be6d3e56SKentaro Takeda out_drop_write: 2073463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2074463c3197SDave Hansen out_dput: 20751da177e4SLinus Torvalds dput(dentry); 20766902d925SDave Hansen out_unlock: 20774ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20781d957f9bSJan Blunck path_put(&nd.path); 20791da177e4SLinus Torvalds putname(tmp); 20806902d925SDave Hansen out_err: 20811da177e4SLinus Torvalds return error; 20821da177e4SLinus Torvalds } 20831da177e4SLinus Torvalds 20845590ff0dSUlrich Drepper asmlinkage long sys_mkdir(const char __user *pathname, int mode) 20855590ff0dSUlrich Drepper { 20865590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 20875590ff0dSUlrich Drepper } 20885590ff0dSUlrich Drepper 20891da177e4SLinus Torvalds /* 20901da177e4SLinus Torvalds * We try to drop the dentry early: we should have 20911da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 20921da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 20931da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 20941da177e4SLinus Torvalds * 20951da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 20961da177e4SLinus Torvalds * do a 20971da177e4SLinus Torvalds * 20981da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 20991da177e4SLinus Torvalds * return -EBUSY; 21001da177e4SLinus Torvalds * 21011da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21021da177e4SLinus Torvalds * that is still in use by something else.. 21031da177e4SLinus Torvalds */ 21041da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21051da177e4SLinus Torvalds { 21061da177e4SLinus Torvalds dget(dentry); 21071da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21081da177e4SLinus Torvalds spin_lock(&dcache_lock); 21091da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21101da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21111da177e4SLinus Torvalds __d_drop(dentry); 21121da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21131da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21141da177e4SLinus Torvalds } 21151da177e4SLinus Torvalds 21161da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21171da177e4SLinus Torvalds { 21181da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21191da177e4SLinus Torvalds 21201da177e4SLinus Torvalds if (error) 21211da177e4SLinus Torvalds return error; 21221da177e4SLinus Torvalds 2123acfa4380SAl Viro if (!dir->i_op->rmdir) 21241da177e4SLinus Torvalds return -EPERM; 21251da177e4SLinus Torvalds 21261da177e4SLinus Torvalds DQUOT_INIT(dir); 21271da177e4SLinus Torvalds 21281b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21291da177e4SLinus Torvalds dentry_unhash(dentry); 21301da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21311da177e4SLinus Torvalds error = -EBUSY; 21321da177e4SLinus Torvalds else { 21331da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21341da177e4SLinus Torvalds if (!error) { 21351da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21361da177e4SLinus Torvalds if (!error) 21371da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21381da177e4SLinus Torvalds } 21391da177e4SLinus Torvalds } 21401b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21411da177e4SLinus Torvalds if (!error) { 21421da177e4SLinus Torvalds d_delete(dentry); 21431da177e4SLinus Torvalds } 21441da177e4SLinus Torvalds dput(dentry); 21451da177e4SLinus Torvalds 21461da177e4SLinus Torvalds return error; 21471da177e4SLinus Torvalds } 21481da177e4SLinus Torvalds 21495590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21501da177e4SLinus Torvalds { 21511da177e4SLinus Torvalds int error = 0; 21521da177e4SLinus Torvalds char * name; 21531da177e4SLinus Torvalds struct dentry *dentry; 21541da177e4SLinus Torvalds struct nameidata nd; 21551da177e4SLinus Torvalds 21562ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 21571da177e4SLinus Torvalds if (error) 21582ad94ae6SAl Viro return error; 21591da177e4SLinus Torvalds 21601da177e4SLinus Torvalds switch(nd.last_type) { 21611da177e4SLinus Torvalds case LAST_DOTDOT: 21621da177e4SLinus Torvalds error = -ENOTEMPTY; 21631da177e4SLinus Torvalds goto exit1; 21641da177e4SLinus Torvalds case LAST_DOT: 21651da177e4SLinus Torvalds error = -EINVAL; 21661da177e4SLinus Torvalds goto exit1; 21671da177e4SLinus Torvalds case LAST_ROOT: 21681da177e4SLinus Torvalds error = -EBUSY; 21691da177e4SLinus Torvalds goto exit1; 21701da177e4SLinus Torvalds } 21710612d9fbSOGAWA Hirofumi 21720612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 21730612d9fbSOGAWA Hirofumi 21744ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 217549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 21761da177e4SLinus Torvalds error = PTR_ERR(dentry); 21776902d925SDave Hansen if (IS_ERR(dentry)) 21786902d925SDave Hansen goto exit2; 21790622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 21800622753bSDave Hansen if (error) 21810622753bSDave Hansen goto exit3; 2182be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2183be6d3e56SKentaro Takeda if (error) 2184be6d3e56SKentaro Takeda goto exit4; 21854ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2186be6d3e56SKentaro Takeda exit4: 21870622753bSDave Hansen mnt_drop_write(nd.path.mnt); 21880622753bSDave Hansen exit3: 21891da177e4SLinus Torvalds dput(dentry); 21906902d925SDave Hansen exit2: 21914ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21921da177e4SLinus Torvalds exit1: 21931d957f9bSJan Blunck path_put(&nd.path); 21941da177e4SLinus Torvalds putname(name); 21951da177e4SLinus Torvalds return error; 21961da177e4SLinus Torvalds } 21971da177e4SLinus Torvalds 21985590ff0dSUlrich Drepper asmlinkage long sys_rmdir(const char __user *pathname) 21995590ff0dSUlrich Drepper { 22005590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22015590ff0dSUlrich Drepper } 22025590ff0dSUlrich Drepper 22031da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22041da177e4SLinus Torvalds { 22051da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22061da177e4SLinus Torvalds 22071da177e4SLinus Torvalds if (error) 22081da177e4SLinus Torvalds return error; 22091da177e4SLinus Torvalds 2210acfa4380SAl Viro if (!dir->i_op->unlink) 22111da177e4SLinus Torvalds return -EPERM; 22121da177e4SLinus Torvalds 22131da177e4SLinus Torvalds DQUOT_INIT(dir); 22141da177e4SLinus Torvalds 22151b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22161da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22171da177e4SLinus Torvalds error = -EBUSY; 22181da177e4SLinus Torvalds else { 22191da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22201da177e4SLinus Torvalds if (!error) 22211da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22221da177e4SLinus Torvalds } 22231b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22241da177e4SLinus Torvalds 22251da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22261da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2227ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22281da177e4SLinus Torvalds d_delete(dentry); 22291da177e4SLinus Torvalds } 22300eeca283SRobert Love 22311da177e4SLinus Torvalds return error; 22321da177e4SLinus Torvalds } 22331da177e4SLinus Torvalds 22341da177e4SLinus Torvalds /* 22351da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22361b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22371da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22381da177e4SLinus Torvalds * while waiting on the I/O. 22391da177e4SLinus Torvalds */ 22405590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22411da177e4SLinus Torvalds { 22422ad94ae6SAl Viro int error; 22431da177e4SLinus Torvalds char *name; 22441da177e4SLinus Torvalds struct dentry *dentry; 22451da177e4SLinus Torvalds struct nameidata nd; 22461da177e4SLinus Torvalds struct inode *inode = NULL; 22471da177e4SLinus Torvalds 22482ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22491da177e4SLinus Torvalds if (error) 22502ad94ae6SAl Viro return error; 22512ad94ae6SAl Viro 22521da177e4SLinus Torvalds error = -EISDIR; 22531da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 22541da177e4SLinus Torvalds goto exit1; 22550612d9fbSOGAWA Hirofumi 22560612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22570612d9fbSOGAWA Hirofumi 22584ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 225949705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22601da177e4SLinus Torvalds error = PTR_ERR(dentry); 22611da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 22621da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 22631da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 22641da177e4SLinus Torvalds goto slashes; 22651da177e4SLinus Torvalds inode = dentry->d_inode; 22661da177e4SLinus Torvalds if (inode) 22671da177e4SLinus Torvalds atomic_inc(&inode->i_count); 22680622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22690622753bSDave Hansen if (error) 22700622753bSDave Hansen goto exit2; 2271be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2272be6d3e56SKentaro Takeda if (error) 2273be6d3e56SKentaro Takeda goto exit3; 22744ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2275be6d3e56SKentaro Takeda exit3: 22760622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22771da177e4SLinus Torvalds exit2: 22781da177e4SLinus Torvalds dput(dentry); 22791da177e4SLinus Torvalds } 22804ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22811da177e4SLinus Torvalds if (inode) 22821da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 22831da177e4SLinus Torvalds exit1: 22841d957f9bSJan Blunck path_put(&nd.path); 22851da177e4SLinus Torvalds putname(name); 22861da177e4SLinus Torvalds return error; 22871da177e4SLinus Torvalds 22881da177e4SLinus Torvalds slashes: 22891da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 22901da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 22911da177e4SLinus Torvalds goto exit2; 22921da177e4SLinus Torvalds } 22931da177e4SLinus Torvalds 22945590ff0dSUlrich Drepper asmlinkage long sys_unlinkat(int dfd, const char __user *pathname, int flag) 22955590ff0dSUlrich Drepper { 22965590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 22975590ff0dSUlrich Drepper return -EINVAL; 22985590ff0dSUlrich Drepper 22995590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23005590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23015590ff0dSUlrich Drepper 23025590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23035590ff0dSUlrich Drepper } 23045590ff0dSUlrich Drepper 23055590ff0dSUlrich Drepper asmlinkage long sys_unlink(const char __user *pathname) 23065590ff0dSUlrich Drepper { 23075590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23085590ff0dSUlrich Drepper } 23095590ff0dSUlrich Drepper 2310db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23111da177e4SLinus Torvalds { 2312a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23131da177e4SLinus Torvalds 23141da177e4SLinus Torvalds if (error) 23151da177e4SLinus Torvalds return error; 23161da177e4SLinus Torvalds 2317acfa4380SAl Viro if (!dir->i_op->symlink) 23181da177e4SLinus Torvalds return -EPERM; 23191da177e4SLinus Torvalds 23201da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23211da177e4SLinus Torvalds if (error) 23221da177e4SLinus Torvalds return error; 23231da177e4SLinus Torvalds 23241da177e4SLinus Torvalds DQUOT_INIT(dir); 23251da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2326a74574aaSStephen Smalley if (!error) 2327f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23281da177e4SLinus Torvalds return error; 23291da177e4SLinus Torvalds } 23301da177e4SLinus Torvalds 23315590ff0dSUlrich Drepper asmlinkage long sys_symlinkat(const char __user *oldname, 23325590ff0dSUlrich Drepper int newdfd, const char __user *newname) 23331da177e4SLinus Torvalds { 23342ad94ae6SAl Viro int error; 23351da177e4SLinus Torvalds char *from; 23361da177e4SLinus Torvalds char *to; 23376902d925SDave Hansen struct dentry *dentry; 23386902d925SDave Hansen struct nameidata nd; 23391da177e4SLinus Torvalds 23401da177e4SLinus Torvalds from = getname(oldname); 23411da177e4SLinus Torvalds if (IS_ERR(from)) 23421da177e4SLinus Torvalds return PTR_ERR(from); 23432ad94ae6SAl Viro 23442ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 23452ad94ae6SAl Viro if (error) 23466902d925SDave Hansen goto out_putname; 23471da177e4SLinus Torvalds 23481da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23491da177e4SLinus Torvalds error = PTR_ERR(dentry); 23506902d925SDave Hansen if (IS_ERR(dentry)) 23516902d925SDave Hansen goto out_unlock; 23526902d925SDave Hansen 235375c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 235475c3f29dSDave Hansen if (error) 235575c3f29dSDave Hansen goto out_dput; 2356be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2357be6d3e56SKentaro Takeda if (error) 2358be6d3e56SKentaro Takeda goto out_drop_write; 2359db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2360be6d3e56SKentaro Takeda out_drop_write: 236175c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 236275c3f29dSDave Hansen out_dput: 23631da177e4SLinus Torvalds dput(dentry); 23646902d925SDave Hansen out_unlock: 23654ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23661d957f9bSJan Blunck path_put(&nd.path); 23671da177e4SLinus Torvalds putname(to); 23686902d925SDave Hansen out_putname: 23691da177e4SLinus Torvalds putname(from); 23701da177e4SLinus Torvalds return error; 23711da177e4SLinus Torvalds } 23721da177e4SLinus Torvalds 23735590ff0dSUlrich Drepper asmlinkage long sys_symlink(const char __user *oldname, const char __user *newname) 23745590ff0dSUlrich Drepper { 23755590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 23765590ff0dSUlrich Drepper } 23775590ff0dSUlrich Drepper 23781da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 23791da177e4SLinus Torvalds { 23801da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 23811da177e4SLinus Torvalds int error; 23821da177e4SLinus Torvalds 23831da177e4SLinus Torvalds if (!inode) 23841da177e4SLinus Torvalds return -ENOENT; 23851da177e4SLinus Torvalds 2386a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 23871da177e4SLinus Torvalds if (error) 23881da177e4SLinus Torvalds return error; 23891da177e4SLinus Torvalds 23901da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 23911da177e4SLinus Torvalds return -EXDEV; 23921da177e4SLinus Torvalds 23931da177e4SLinus Torvalds /* 23941da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 23951da177e4SLinus Torvalds */ 23961da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 23971da177e4SLinus Torvalds return -EPERM; 2398acfa4380SAl Viro if (!dir->i_op->link) 23991da177e4SLinus Torvalds return -EPERM; 24007e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24011da177e4SLinus Torvalds return -EPERM; 24021da177e4SLinus Torvalds 24031da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24041da177e4SLinus Torvalds if (error) 24051da177e4SLinus Torvalds return error; 24061da177e4SLinus Torvalds 24077e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24081da177e4SLinus Torvalds DQUOT_INIT(dir); 24091da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24107e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2411e31e14ecSStephen Smalley if (!error) 24127e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24131da177e4SLinus Torvalds return error; 24141da177e4SLinus Torvalds } 24151da177e4SLinus Torvalds 24161da177e4SLinus Torvalds /* 24171da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24181da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24191da177e4SLinus Torvalds * newname. --KAB 24201da177e4SLinus Torvalds * 24211da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24221da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24231da177e4SLinus Torvalds * and other special files. --ADM 24241da177e4SLinus Torvalds */ 24255590ff0dSUlrich Drepper asmlinkage long sys_linkat(int olddfd, const char __user *oldname, 2426c04030e1SUlrich Drepper int newdfd, const char __user *newname, 2427c04030e1SUlrich Drepper int flags) 24281da177e4SLinus Torvalds { 24291da177e4SLinus Torvalds struct dentry *new_dentry; 24302d8f3038SAl Viro struct nameidata nd; 24312d8f3038SAl Viro struct path old_path; 24321da177e4SLinus Torvalds int error; 24331da177e4SLinus Torvalds char *to; 24341da177e4SLinus Torvalds 243545c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2436c04030e1SUlrich Drepper return -EINVAL; 2437c04030e1SUlrich Drepper 24382d8f3038SAl Viro error = user_path_at(olddfd, oldname, 243945c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24402d8f3038SAl Viro &old_path); 24411da177e4SLinus Torvalds if (error) 24422ad94ae6SAl Viro return error; 24432ad94ae6SAl Viro 24442ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24451da177e4SLinus Torvalds if (error) 24461da177e4SLinus Torvalds goto out; 24471da177e4SLinus Torvalds error = -EXDEV; 24482d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 24491da177e4SLinus Torvalds goto out_release; 24501da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24511da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24526902d925SDave Hansen if (IS_ERR(new_dentry)) 24536902d925SDave Hansen goto out_unlock; 245475c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 245575c3f29dSDave Hansen if (error) 245675c3f29dSDave Hansen goto out_dput; 2457be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2458be6d3e56SKentaro Takeda if (error) 2459be6d3e56SKentaro Takeda goto out_drop_write; 24602d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2461be6d3e56SKentaro Takeda out_drop_write: 246275c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 246375c3f29dSDave Hansen out_dput: 24641da177e4SLinus Torvalds dput(new_dentry); 24656902d925SDave Hansen out_unlock: 24664ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24671da177e4SLinus Torvalds out_release: 24681d957f9bSJan Blunck path_put(&nd.path); 24692ad94ae6SAl Viro putname(to); 24701da177e4SLinus Torvalds out: 24712d8f3038SAl Viro path_put(&old_path); 24721da177e4SLinus Torvalds 24731da177e4SLinus Torvalds return error; 24741da177e4SLinus Torvalds } 24751da177e4SLinus Torvalds 24765590ff0dSUlrich Drepper asmlinkage long sys_link(const char __user *oldname, const char __user *newname) 24775590ff0dSUlrich Drepper { 2478c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 24795590ff0dSUlrich Drepper } 24805590ff0dSUlrich Drepper 24811da177e4SLinus Torvalds /* 24821da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 24831da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 24841da177e4SLinus Torvalds * Problems: 24851da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 24861da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 24871da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2488a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 24891da177e4SLinus Torvalds * story. 24901da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 24911b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 24921da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 24931da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2494a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 24951da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 24961da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 24971da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2498a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 24991da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25001da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25011da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25021da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25031da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25041da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25051da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25061da177e4SLinus Torvalds * trick as in rmdir(). 25071da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25081b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25091da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25101b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25111da177e4SLinus Torvalds * locking]. 25121da177e4SLinus Torvalds */ 251375c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25141da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25151da177e4SLinus Torvalds { 25161da177e4SLinus Torvalds int error = 0; 25171da177e4SLinus Torvalds struct inode *target; 25181da177e4SLinus Torvalds 25191da177e4SLinus Torvalds /* 25201da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25211da177e4SLinus Torvalds * we'll need to flip '..'. 25221da177e4SLinus Torvalds */ 25231da177e4SLinus Torvalds if (new_dir != old_dir) { 2524f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25251da177e4SLinus Torvalds if (error) 25261da177e4SLinus Torvalds return error; 25271da177e4SLinus Torvalds } 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25301da177e4SLinus Torvalds if (error) 25311da177e4SLinus Torvalds return error; 25321da177e4SLinus Torvalds 25331da177e4SLinus Torvalds target = new_dentry->d_inode; 25341da177e4SLinus Torvalds if (target) { 25351b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25361da177e4SLinus Torvalds dentry_unhash(new_dentry); 25371da177e4SLinus Torvalds } 25381da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25391da177e4SLinus Torvalds error = -EBUSY; 25401da177e4SLinus Torvalds else 25411da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25421da177e4SLinus Torvalds if (target) { 25431da177e4SLinus Torvalds if (!error) 25441da177e4SLinus Torvalds target->i_flags |= S_DEAD; 25451b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25461da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 25471da177e4SLinus Torvalds d_rehash(new_dentry); 25481da177e4SLinus Torvalds dput(new_dentry); 25491da177e4SLinus Torvalds } 2550e31e14ecSStephen Smalley if (!error) 2551349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25521da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25531da177e4SLinus Torvalds return error; 25541da177e4SLinus Torvalds } 25551da177e4SLinus Torvalds 255675c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 25571da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25581da177e4SLinus Torvalds { 25591da177e4SLinus Torvalds struct inode *target; 25601da177e4SLinus Torvalds int error; 25611da177e4SLinus Torvalds 25621da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25631da177e4SLinus Torvalds if (error) 25641da177e4SLinus Torvalds return error; 25651da177e4SLinus Torvalds 25661da177e4SLinus Torvalds dget(new_dentry); 25671da177e4SLinus Torvalds target = new_dentry->d_inode; 25681da177e4SLinus Torvalds if (target) 25691b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25701da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25711da177e4SLinus Torvalds error = -EBUSY; 25721da177e4SLinus Torvalds else 25731da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25741da177e4SLinus Torvalds if (!error) { 2575349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25761da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 25771da177e4SLinus Torvalds } 25781da177e4SLinus Torvalds if (target) 25791b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25801da177e4SLinus Torvalds dput(new_dentry); 25811da177e4SLinus Torvalds return error; 25821da177e4SLinus Torvalds } 25831da177e4SLinus Torvalds 25841da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 25851da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25861da177e4SLinus Torvalds { 25871da177e4SLinus Torvalds int error; 25881da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 25890eeca283SRobert Love const char *old_name; 25901da177e4SLinus Torvalds 25911da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 25921da177e4SLinus Torvalds return 0; 25931da177e4SLinus Torvalds 25941da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 25951da177e4SLinus Torvalds if (error) 25961da177e4SLinus Torvalds return error; 25971da177e4SLinus Torvalds 25981da177e4SLinus Torvalds if (!new_dentry->d_inode) 2599a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 26001da177e4SLinus Torvalds else 26011da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26021da177e4SLinus Torvalds if (error) 26031da177e4SLinus Torvalds return error; 26041da177e4SLinus Torvalds 2605acfa4380SAl Viro if (!old_dir->i_op->rename) 26061da177e4SLinus Torvalds return -EPERM; 26071da177e4SLinus Torvalds 26081da177e4SLinus Torvalds DQUOT_INIT(old_dir); 26091da177e4SLinus Torvalds DQUOT_INIT(new_dir); 26101da177e4SLinus Torvalds 26110eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26120eeca283SRobert Love 26131da177e4SLinus Torvalds if (is_dir) 26141da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26151da177e4SLinus Torvalds else 26161da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26171da177e4SLinus Torvalds if (!error) { 26180eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 261989204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26205a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26211da177e4SLinus Torvalds } 26220eeca283SRobert Love fsnotify_oldname_free(old_name); 26230eeca283SRobert Love 26241da177e4SLinus Torvalds return error; 26251da177e4SLinus Torvalds } 26261da177e4SLinus Torvalds 26272ad94ae6SAl Viro asmlinkage long sys_renameat(int olddfd, const char __user *oldname, 26282ad94ae6SAl Viro int newdfd, const char __user *newname) 26291da177e4SLinus Torvalds { 26301da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26311da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26321da177e4SLinus Torvalds struct dentry *trap; 26331da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26342ad94ae6SAl Viro char *from; 26352ad94ae6SAl Viro char *to; 26362ad94ae6SAl Viro int error; 26371da177e4SLinus Torvalds 26382ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26391da177e4SLinus Torvalds if (error) 26401da177e4SLinus Torvalds goto exit; 26411da177e4SLinus Torvalds 26422ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 26431da177e4SLinus Torvalds if (error) 26441da177e4SLinus Torvalds goto exit1; 26451da177e4SLinus Torvalds 26461da177e4SLinus Torvalds error = -EXDEV; 26474ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 26481da177e4SLinus Torvalds goto exit2; 26491da177e4SLinus Torvalds 26504ac91378SJan Blunck old_dir = oldnd.path.dentry; 26511da177e4SLinus Torvalds error = -EBUSY; 26521da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 26531da177e4SLinus Torvalds goto exit2; 26541da177e4SLinus Torvalds 26554ac91378SJan Blunck new_dir = newnd.path.dentry; 26561da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 26571da177e4SLinus Torvalds goto exit2; 26581da177e4SLinus Torvalds 26590612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 26600612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 26614e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 26620612d9fbSOGAWA Hirofumi 26631da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 26641da177e4SLinus Torvalds 266549705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 26661da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 26671da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 26681da177e4SLinus Torvalds goto exit3; 26691da177e4SLinus Torvalds /* source must exist */ 26701da177e4SLinus Torvalds error = -ENOENT; 26711da177e4SLinus Torvalds if (!old_dentry->d_inode) 26721da177e4SLinus Torvalds goto exit4; 26731da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 26741da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 26751da177e4SLinus Torvalds error = -ENOTDIR; 26761da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 26771da177e4SLinus Torvalds goto exit4; 26781da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 26791da177e4SLinus Torvalds goto exit4; 26801da177e4SLinus Torvalds } 26811da177e4SLinus Torvalds /* source should not be ancestor of target */ 26821da177e4SLinus Torvalds error = -EINVAL; 26831da177e4SLinus Torvalds if (old_dentry == trap) 26841da177e4SLinus Torvalds goto exit4; 268549705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 26861da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 26871da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 26881da177e4SLinus Torvalds goto exit4; 26891da177e4SLinus Torvalds /* target should not be an ancestor of source */ 26901da177e4SLinus Torvalds error = -ENOTEMPTY; 26911da177e4SLinus Torvalds if (new_dentry == trap) 26921da177e4SLinus Torvalds goto exit5; 26931da177e4SLinus Torvalds 26949079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 26959079b1ebSDave Hansen if (error) 26969079b1ebSDave Hansen goto exit5; 2697be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 2698be6d3e56SKentaro Takeda &newnd.path, new_dentry); 2699be6d3e56SKentaro Takeda if (error) 2700be6d3e56SKentaro Takeda goto exit6; 27011da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27021da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 2703be6d3e56SKentaro Takeda exit6: 27049079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27051da177e4SLinus Torvalds exit5: 27061da177e4SLinus Torvalds dput(new_dentry); 27071da177e4SLinus Torvalds exit4: 27081da177e4SLinus Torvalds dput(old_dentry); 27091da177e4SLinus Torvalds exit3: 27101da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27111da177e4SLinus Torvalds exit2: 27121d957f9bSJan Blunck path_put(&newnd.path); 27132ad94ae6SAl Viro putname(to); 27141da177e4SLinus Torvalds exit1: 27151d957f9bSJan Blunck path_put(&oldnd.path); 27161da177e4SLinus Torvalds putname(from); 27172ad94ae6SAl Viro exit: 27181da177e4SLinus Torvalds return error; 27191da177e4SLinus Torvalds } 27201da177e4SLinus Torvalds 27215590ff0dSUlrich Drepper asmlinkage long sys_rename(const char __user *oldname, const char __user *newname) 27225590ff0dSUlrich Drepper { 27235590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27245590ff0dSUlrich Drepper } 27255590ff0dSUlrich Drepper 27261da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27271da177e4SLinus Torvalds { 27281da177e4SLinus Torvalds int len; 27291da177e4SLinus Torvalds 27301da177e4SLinus Torvalds len = PTR_ERR(link); 27311da177e4SLinus Torvalds if (IS_ERR(link)) 27321da177e4SLinus Torvalds goto out; 27331da177e4SLinus Torvalds 27341da177e4SLinus Torvalds len = strlen(link); 27351da177e4SLinus Torvalds if (len > (unsigned) buflen) 27361da177e4SLinus Torvalds len = buflen; 27371da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27381da177e4SLinus Torvalds len = -EFAULT; 27391da177e4SLinus Torvalds out: 27401da177e4SLinus Torvalds return len; 27411da177e4SLinus Torvalds } 27421da177e4SLinus Torvalds 27431da177e4SLinus Torvalds /* 27441da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 27451da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 27461da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 27471da177e4SLinus Torvalds */ 27481da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27491da177e4SLinus Torvalds { 27501da177e4SLinus Torvalds struct nameidata nd; 2751cc314eefSLinus Torvalds void *cookie; 2752694a1764SMarcin Slusarz int res; 2753cc314eefSLinus Torvalds 27541da177e4SLinus Torvalds nd.depth = 0; 2755cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2756694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2757694a1764SMarcin Slusarz return PTR_ERR(cookie); 2758694a1764SMarcin Slusarz 2759694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 27601da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2761cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2762694a1764SMarcin Slusarz return res; 27631da177e4SLinus Torvalds } 27641da177e4SLinus Torvalds 27651da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 27661da177e4SLinus Torvalds { 27671da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 27681da177e4SLinus Torvalds } 27691da177e4SLinus Torvalds 27701da177e4SLinus Torvalds /* get the link contents into pagecache */ 27711da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 27721da177e4SLinus Torvalds { 2773ebd09abbSDuane Griffin char *kaddr; 27741da177e4SLinus Torvalds struct page *page; 27751da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2776090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 27771da177e4SLinus Torvalds if (IS_ERR(page)) 27786fe6900eSNick Piggin return (char*)page; 27791da177e4SLinus Torvalds *ppage = page; 2780ebd09abbSDuane Griffin kaddr = kmap(page); 2781ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 2782ebd09abbSDuane Griffin return kaddr; 27831da177e4SLinus Torvalds } 27841da177e4SLinus Torvalds 27851da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27861da177e4SLinus Torvalds { 27871da177e4SLinus Torvalds struct page *page = NULL; 27881da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 27891da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 27901da177e4SLinus Torvalds if (page) { 27911da177e4SLinus Torvalds kunmap(page); 27921da177e4SLinus Torvalds page_cache_release(page); 27931da177e4SLinus Torvalds } 27941da177e4SLinus Torvalds return res; 27951da177e4SLinus Torvalds } 27961da177e4SLinus Torvalds 2797cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 27981da177e4SLinus Torvalds { 2799cc314eefSLinus Torvalds struct page *page = NULL; 28001da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2801cc314eefSLinus Torvalds return page; 28021da177e4SLinus Torvalds } 28031da177e4SLinus Torvalds 2804cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28051da177e4SLinus Torvalds { 2806cc314eefSLinus Torvalds struct page *page = cookie; 2807cc314eefSLinus Torvalds 2808cc314eefSLinus Torvalds if (page) { 28091da177e4SLinus Torvalds kunmap(page); 28101da177e4SLinus Torvalds page_cache_release(page); 28111da177e4SLinus Torvalds } 28121da177e4SLinus Torvalds } 28131da177e4SLinus Torvalds 28140adb25d2SKirill Korotaev int __page_symlink(struct inode *inode, const char *symname, int len, 28150adb25d2SKirill Korotaev gfp_t gfp_mask) 28161da177e4SLinus Torvalds { 28171da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28180adb25d2SKirill Korotaev struct page *page; 2819afddba49SNick Piggin void *fsdata; 2820beb497abSDmitriy Monakhov int err; 28211da177e4SLinus Torvalds char *kaddr; 28221da177e4SLinus Torvalds 28237e53cac4SNeilBrown retry: 2824afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 2825afddba49SNick Piggin AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 28261da177e4SLinus Torvalds if (err) 2827afddba49SNick Piggin goto fail; 2828afddba49SNick Piggin 28291da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28301da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28311da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2832afddba49SNick Piggin 2833afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2834afddba49SNick Piggin page, fsdata); 28351da177e4SLinus Torvalds if (err < 0) 28361da177e4SLinus Torvalds goto fail; 2837afddba49SNick Piggin if (err < len-1) 2838afddba49SNick Piggin goto retry; 2839afddba49SNick Piggin 28401da177e4SLinus Torvalds mark_inode_dirty(inode); 28411da177e4SLinus Torvalds return 0; 28421da177e4SLinus Torvalds fail: 28431da177e4SLinus Torvalds return err; 28441da177e4SLinus Torvalds } 28451da177e4SLinus Torvalds 28460adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 28470adb25d2SKirill Korotaev { 28480adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 28490adb25d2SKirill Korotaev mapping_gfp_mask(inode->i_mapping)); 28500adb25d2SKirill Korotaev } 28510adb25d2SKirill Korotaev 285292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 28531da177e4SLinus Torvalds .readlink = generic_readlink, 28541da177e4SLinus Torvalds .follow_link = page_follow_link_light, 28551da177e4SLinus Torvalds .put_link = page_put_link, 28561da177e4SLinus Torvalds }; 28571da177e4SLinus Torvalds 28582d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 28591da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 28601da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 28611da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 28621da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 28631da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 28641da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 28651da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 28661da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 28671da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 28680adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 28691da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 28701da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 28711da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2872d1811465SAl Viro EXPORT_SYMBOL(kern_path); 287316f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2874f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 28758c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 28761da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 28771da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 28781da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 28791da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 28801da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 28811da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 28821da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 28831da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 28841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 28851da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 28861da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 28871da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 28881da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 28891da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 289018d8fda7SAl Viro 289118d8fda7SAl Viro /* to be mentioned only in INIT_TASK */ 289218d8fda7SAl Viro struct fs_struct init_fs = { 289318d8fda7SAl Viro .count = ATOMIC_INIT(1), 28941239f26cSSteven Rostedt .lock = __RW_LOCK_UNLOCKED(init_fs.lock), 289518d8fda7SAl Viro .umask = 0022, 289618d8fda7SAl Viro }; 2897