11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/quotaops.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 361da177e4SLinus Torvalds #include <asm/uaccess.h> 371da177e4SLinus Torvalds 38e81e3f4dSEric Paris #include "internal.h" 39e81e3f4dSEric Paris 401da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 411da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 421da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 431da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 441da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 451da177e4SLinus Torvalds * 461da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 471da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 481da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 491da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 501da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 511da177e4SLinus Torvalds * the special cases of the former code. 521da177e4SLinus Torvalds * 531da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 541da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 551da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 561da177e4SLinus Torvalds * 571da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 581da177e4SLinus Torvalds * resolution to correspond with current state of the code. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 611da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 621da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 631da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 641da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 651da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 661da177e4SLinus Torvalds */ 671da177e4SLinus Torvalds 681da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 691da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 701da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 711da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 721da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 731da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 741da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 751da177e4SLinus Torvalds * 761da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 771da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 781da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 791da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 801da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 811da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 821da177e4SLinus Torvalds * and in the old Linux semantics. 831da177e4SLinus Torvalds */ 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 861da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 871da177e4SLinus Torvalds * 881da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 921da177e4SLinus Torvalds * inside the path - always follow. 931da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 941da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 951da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 961da177e4SLinus Torvalds * otherwise - don't follow. 971da177e4SLinus Torvalds * (applied in that order). 981da177e4SLinus Torvalds * 991da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1001da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1011da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1021da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1031da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1041da177e4SLinus Torvalds */ 1051da177e4SLinus Torvalds /* 1061da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 107a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1081da177e4SLinus Torvalds * any extra contention... 1091da177e4SLinus Torvalds */ 1101da177e4SLinus Torvalds 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 1705909ccaaSLinus Torvalds /* 1715909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1725909ccaaSLinus Torvalds */ 1735909ccaaSLinus Torvalds static int acl_permission_check(struct inode *inode, int mask, 1745909ccaaSLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1755909ccaaSLinus Torvalds { 1765909ccaaSLinus Torvalds umode_t mode = inode->i_mode; 1775909ccaaSLinus Torvalds 1785909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 1795909ccaaSLinus Torvalds 1805909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1815909ccaaSLinus Torvalds mode >>= 6; 1825909ccaaSLinus Torvalds else { 1835909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1845909ccaaSLinus Torvalds int error = check_acl(inode, mask); 1855909ccaaSLinus Torvalds if (error != -EAGAIN) 1865909ccaaSLinus Torvalds return error; 1875909ccaaSLinus Torvalds } 1885909ccaaSLinus Torvalds 1895909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1905909ccaaSLinus Torvalds mode >>= 3; 1915909ccaaSLinus Torvalds } 1925909ccaaSLinus Torvalds 1935909ccaaSLinus Torvalds /* 1945909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 1955909ccaaSLinus Torvalds */ 1965909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 1975909ccaaSLinus Torvalds return 0; 1985909ccaaSLinus Torvalds return -EACCES; 1995909ccaaSLinus Torvalds } 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds /** 2021da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2031da177e4SLinus Torvalds * @inode: inode to check access rights for 2041da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2051da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 2061da177e4SLinus Torvalds * 2071da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2081da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2091da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 2101da177e4SLinus Torvalds * are used for other things.. 2111da177e4SLinus Torvalds */ 2121da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 2131da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 2141da177e4SLinus Torvalds { 2155909ccaaSLinus Torvalds int ret; 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds /* 2185909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2191da177e4SLinus Torvalds */ 2205909ccaaSLinus Torvalds ret = acl_permission_check(inode, mask, check_acl); 2215909ccaaSLinus Torvalds if (ret != -EACCES) 2225909ccaaSLinus Torvalds return ret; 2231da177e4SLinus Torvalds 2241da177e4SLinus Torvalds /* 2251da177e4SLinus Torvalds * Read/write DACs are always overridable. 2261da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2271da177e4SLinus Torvalds */ 228f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2291da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2301da177e4SLinus Torvalds return 0; 2311da177e4SLinus Torvalds 2321da177e4SLinus Torvalds /* 2331da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2341da177e4SLinus Torvalds */ 2357ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2361da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2371da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2381da177e4SLinus Torvalds return 0; 2391da177e4SLinus Torvalds 2401da177e4SLinus Torvalds return -EACCES; 2411da177e4SLinus Torvalds } 2421da177e4SLinus Torvalds 243cb23beb5SChristoph Hellwig /** 244cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 245cb23beb5SChristoph Hellwig * @inode: inode to check permission on 246cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 247cb23beb5SChristoph Hellwig * 248cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 249cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 250cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 251cb23beb5SChristoph Hellwig * are used for other things. 252cb23beb5SChristoph Hellwig */ 253f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2541da177e4SLinus Torvalds { 255e6305c43SAl Viro int retval; 2561da177e4SLinus Torvalds 2571da177e4SLinus Torvalds if (mask & MAY_WRITE) { 25822590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2591da177e4SLinus Torvalds 2601da177e4SLinus Torvalds /* 2611da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2621da177e4SLinus Torvalds */ 2631da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2641da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2651da177e4SLinus Torvalds return -EROFS; 2661da177e4SLinus Torvalds 2671da177e4SLinus Torvalds /* 2681da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2691da177e4SLinus Torvalds */ 2701da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2711da177e4SLinus Torvalds return -EACCES; 2721da177e4SLinus Torvalds } 2731da177e4SLinus Torvalds 274acfa4380SAl Viro if (inode->i_op->permission) 275b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 276f696a365SMiklos Szeredi else 2775909ccaaSLinus Torvalds retval = generic_permission(inode, mask, inode->i_op->check_acl); 278f696a365SMiklos Szeredi 2791da177e4SLinus Torvalds if (retval) 2801da177e4SLinus Torvalds return retval; 2811da177e4SLinus Torvalds 28208ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 28308ce5f16SSerge E. Hallyn if (retval) 28408ce5f16SSerge E. Hallyn return retval; 28508ce5f16SSerge E. Hallyn 286e6305c43SAl Viro return security_inode_permission(inode, 287f418b006SStephen Smalley mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); 2881da177e4SLinus Torvalds } 2891da177e4SLinus Torvalds 290e4543eddSChristoph Hellwig /** 2918c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2928c744fb8SChristoph Hellwig * @file: file to check access rights for 2938c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2948c744fb8SChristoph Hellwig * 2958c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 2968c744fb8SChristoph Hellwig * file. 2978c744fb8SChristoph Hellwig * 2988c744fb8SChristoph Hellwig * Note: 2998c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 300cb23beb5SChristoph Hellwig * be done using inode_permission(). 3018c744fb8SChristoph Hellwig */ 3028c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3038c744fb8SChristoph Hellwig { 304f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3058c744fb8SChristoph Hellwig } 3068c744fb8SChristoph Hellwig 3071da177e4SLinus Torvalds /* 3081da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3091da177e4SLinus Torvalds * put_write_access() releases this write permission. 3101da177e4SLinus Torvalds * This is used for regular files. 3111da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3121da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3131da177e4SLinus Torvalds * can have the following values: 3141da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3151da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3161da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3171da177e4SLinus Torvalds * 3181da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3191da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3201da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3211da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3221da177e4SLinus Torvalds * the inode->i_lock spinlock. 3231da177e4SLinus Torvalds */ 3241da177e4SLinus Torvalds 3251da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3261da177e4SLinus Torvalds { 3271da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3281da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3291da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3301da177e4SLinus Torvalds return -ETXTBSY; 3311da177e4SLinus Torvalds } 3321da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3331da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3341da177e4SLinus Torvalds 3351da177e4SLinus Torvalds return 0; 3361da177e4SLinus Torvalds } 3371da177e4SLinus Torvalds 3381da177e4SLinus Torvalds int deny_write_access(struct file * file) 3391da177e4SLinus Torvalds { 3400f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3431da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3441da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3451da177e4SLinus Torvalds return -ETXTBSY; 3461da177e4SLinus Torvalds } 3471da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3481da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3491da177e4SLinus Torvalds 3501da177e4SLinus Torvalds return 0; 3511da177e4SLinus Torvalds } 3521da177e4SLinus Torvalds 3531d957f9bSJan Blunck /** 3545dd784d0SJan Blunck * path_get - get a reference to a path 3555dd784d0SJan Blunck * @path: path to get the reference to 3565dd784d0SJan Blunck * 3575dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3585dd784d0SJan Blunck */ 3595dd784d0SJan Blunck void path_get(struct path *path) 3605dd784d0SJan Blunck { 3615dd784d0SJan Blunck mntget(path->mnt); 3625dd784d0SJan Blunck dget(path->dentry); 3635dd784d0SJan Blunck } 3645dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3655dd784d0SJan Blunck 3665dd784d0SJan Blunck /** 3671d957f9bSJan Blunck * path_put - put a reference to a path 3681d957f9bSJan Blunck * @path: path to put the reference to 3691d957f9bSJan Blunck * 3701d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3711d957f9bSJan Blunck */ 3721d957f9bSJan Blunck void path_put(struct path *path) 3731da177e4SLinus Torvalds { 3741d957f9bSJan Blunck dput(path->dentry); 3751d957f9bSJan Blunck mntput(path->mnt); 3761da177e4SLinus Torvalds } 3771d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3781da177e4SLinus Torvalds 379834f2a4aSTrond Myklebust /** 380834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 381834f2a4aSTrond Myklebust * @nd: pointer to nameidata 382834f2a4aSTrond Myklebust */ 383834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 384834f2a4aSTrond Myklebust { 3850f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 386834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 387834f2a4aSTrond Myklebust else 388834f2a4aSTrond Myklebust fput(nd->intent.open.file); 389834f2a4aSTrond Myklebust } 390834f2a4aSTrond Myklebust 391bcdc5e01SIan Kent static inline struct dentry * 392bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 393bcdc5e01SIan Kent { 394bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 395bcdc5e01SIan Kent if (unlikely(status <= 0)) { 396bcdc5e01SIan Kent /* 397bcdc5e01SIan Kent * The dentry failed validation. 398bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 399bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 400bcdc5e01SIan Kent * to return a fail status. 401bcdc5e01SIan Kent */ 402bcdc5e01SIan Kent if (!status) { 403bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 404bcdc5e01SIan Kent dput(dentry); 405bcdc5e01SIan Kent dentry = NULL; 406bcdc5e01SIan Kent } 407bcdc5e01SIan Kent } else { 408bcdc5e01SIan Kent dput(dentry); 409bcdc5e01SIan Kent dentry = ERR_PTR(status); 410bcdc5e01SIan Kent } 411bcdc5e01SIan Kent } 412bcdc5e01SIan Kent return dentry; 413bcdc5e01SIan Kent } 414bcdc5e01SIan Kent 4151da177e4SLinus Torvalds /* 41639159de2SJeff Layton * force_reval_path - force revalidation of a dentry 41739159de2SJeff Layton * 41839159de2SJeff Layton * In some situations the path walking code will trust dentries without 41939159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 42039159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 42139159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 42239159de2SJeff Layton * a d_revalidate call before proceeding. 42339159de2SJeff Layton * 42439159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 42539159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 42639159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 42739159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 42839159de2SJeff Layton * to the path if necessary. 42939159de2SJeff Layton */ 43039159de2SJeff Layton static int 43139159de2SJeff Layton force_reval_path(struct path *path, struct nameidata *nd) 43239159de2SJeff Layton { 43339159de2SJeff Layton int status; 43439159de2SJeff Layton struct dentry *dentry = path->dentry; 43539159de2SJeff Layton 43639159de2SJeff Layton /* 43739159de2SJeff Layton * only check on filesystems where it's possible for the dentry to 43839159de2SJeff Layton * become stale. It's assumed that if this flag is set then the 43939159de2SJeff Layton * d_revalidate op will also be defined. 44039159de2SJeff Layton */ 44139159de2SJeff Layton if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) 44239159de2SJeff Layton return 0; 44339159de2SJeff Layton 44439159de2SJeff Layton status = dentry->d_op->d_revalidate(dentry, nd); 44539159de2SJeff Layton if (status > 0) 44639159de2SJeff Layton return 0; 44739159de2SJeff Layton 44839159de2SJeff Layton if (!status) { 44939159de2SJeff Layton d_invalidate(dentry); 45039159de2SJeff Layton status = -ESTALE; 45139159de2SJeff Layton } 45239159de2SJeff Layton return status; 45339159de2SJeff Layton } 45439159de2SJeff Layton 45539159de2SJeff Layton /* 456b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 457b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 458b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 4591da177e4SLinus Torvalds * 4601da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 461b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 4621da177e4SLinus Torvalds * complete permission check. 4631da177e4SLinus Torvalds */ 464b75b5086SAl Viro static int exec_permission(struct inode *inode) 4651da177e4SLinus Torvalds { 4665909ccaaSLinus Torvalds int ret; 4671da177e4SLinus Torvalds 468cb9179eaSLinus Torvalds if (inode->i_op->permission) { 4695909ccaaSLinus Torvalds ret = inode->i_op->permission(inode, MAY_EXEC); 470cb9179eaSLinus Torvalds if (!ret) 471cb9179eaSLinus Torvalds goto ok; 472cb9179eaSLinus Torvalds return ret; 473cb9179eaSLinus Torvalds } 4745909ccaaSLinus Torvalds ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl); 4755909ccaaSLinus Torvalds if (!ret) 4761da177e4SLinus Torvalds goto ok; 4771da177e4SLinus Torvalds 478f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 4791da177e4SLinus Torvalds goto ok; 4801da177e4SLinus Torvalds 4815909ccaaSLinus Torvalds return ret; 4821da177e4SLinus Torvalds ok: 483b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4841da177e4SLinus Torvalds } 4851da177e4SLinus Torvalds 4862a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 4872a737871SAl Viro { 4882a737871SAl Viro if (!nd->root.mnt) { 4892a737871SAl Viro struct fs_struct *fs = current->fs; 4902a737871SAl Viro read_lock(&fs->lock); 4912a737871SAl Viro nd->root = fs->root; 4922a737871SAl Viro path_get(&nd->root); 4932a737871SAl Viro read_unlock(&fs->lock); 4942a737871SAl Viro } 4952a737871SAl Viro } 4962a737871SAl Viro 4976de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 4986de88d72SAl Viro 499f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5001da177e4SLinus Torvalds { 5011da177e4SLinus Torvalds int res = 0; 5021da177e4SLinus Torvalds char *name; 5031da177e4SLinus Torvalds if (IS_ERR(link)) 5041da177e4SLinus Torvalds goto fail; 5051da177e4SLinus Torvalds 5061da177e4SLinus Torvalds if (*link == '/') { 5072a737871SAl Viro set_root(nd); 5081d957f9bSJan Blunck path_put(&nd->path); 5092a737871SAl Viro nd->path = nd->root; 5102a737871SAl Viro path_get(&nd->root); 5111da177e4SLinus Torvalds } 512b4091d5fSChristoph Hellwig 5131da177e4SLinus Torvalds res = link_path_walk(link, nd); 5141da177e4SLinus Torvalds if (nd->depth || res || nd->last_type!=LAST_NORM) 5151da177e4SLinus Torvalds return res; 5161da177e4SLinus Torvalds /* 5171da177e4SLinus Torvalds * If it is an iterative symlinks resolution in open_namei() we 5181da177e4SLinus Torvalds * have to copy the last component. And all that crap because of 5191da177e4SLinus Torvalds * bloody create() on broken symlinks. Furrfu... 5201da177e4SLinus Torvalds */ 5211da177e4SLinus Torvalds name = __getname(); 5221da177e4SLinus Torvalds if (unlikely(!name)) { 5231d957f9bSJan Blunck path_put(&nd->path); 5241da177e4SLinus Torvalds return -ENOMEM; 5251da177e4SLinus Torvalds } 5261da177e4SLinus Torvalds strcpy(name, nd->last.name); 5271da177e4SLinus Torvalds nd->last.name = name; 5281da177e4SLinus Torvalds return 0; 5291da177e4SLinus Torvalds fail: 5301d957f9bSJan Blunck path_put(&nd->path); 5311da177e4SLinus Torvalds return PTR_ERR(link); 5321da177e4SLinus Torvalds } 5331da177e4SLinus Torvalds 5341d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 535051d3812SIan Kent { 536051d3812SIan Kent dput(path->dentry); 5374ac91378SJan Blunck if (path->mnt != nd->path.mnt) 538051d3812SIan Kent mntput(path->mnt); 539051d3812SIan Kent } 540051d3812SIan Kent 541051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 542051d3812SIan Kent { 5434ac91378SJan Blunck dput(nd->path.dentry); 5444ac91378SJan Blunck if (nd->path.mnt != path->mnt) 5454ac91378SJan Blunck mntput(nd->path.mnt); 5464ac91378SJan Blunck nd->path.mnt = path->mnt; 5474ac91378SJan Blunck nd->path.dentry = path->dentry; 548051d3812SIan Kent } 549051d3812SIan Kent 550f1662356SArjan van de Ven static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd) 5511da177e4SLinus Torvalds { 5521da177e4SLinus Torvalds int error; 553cc314eefSLinus Torvalds void *cookie; 554cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 5551da177e4SLinus Torvalds 556d671a1cbSAl Viro touch_atime(path->mnt, dentry); 5571da177e4SLinus Torvalds nd_set_link(nd, NULL); 558cd4e91d3SAl Viro 5594ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 560051d3812SIan Kent path_to_nameidata(path, nd); 561051d3812SIan Kent dget(dentry); 562051d3812SIan Kent } 563cd4e91d3SAl Viro mntget(path->mnt); 56486acdca1SAl Viro nd->last_type = LAST_BIND; 565cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, nd); 566cc314eefSLinus Torvalds error = PTR_ERR(cookie); 567cc314eefSLinus Torvalds if (!IS_ERR(cookie)) { 5681da177e4SLinus Torvalds char *s = nd_get_link(nd); 569cc314eefSLinus Torvalds error = 0; 5701da177e4SLinus Torvalds if (s) 5711da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 57239159de2SJeff Layton else if (nd->last_type == LAST_BIND) { 57339159de2SJeff Layton error = force_reval_path(&nd->path, nd); 57439159de2SJeff Layton if (error) 57539159de2SJeff Layton path_put(&nd->path); 57639159de2SJeff Layton } 5771da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 578cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, nd, cookie); 5791da177e4SLinus Torvalds } 5801da177e4SLinus Torvalds return error; 5811da177e4SLinus Torvalds } 5821da177e4SLinus Torvalds 5831da177e4SLinus Torvalds /* 5841da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 5851da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 5861da177e4SLinus Torvalds * 5871da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 5881da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 5891da177e4SLinus Torvalds */ 59090ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 5911da177e4SLinus Torvalds { 5921da177e4SLinus Torvalds int err = -ELOOP; 5931da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 5941da177e4SLinus Torvalds goto loop; 5951da177e4SLinus Torvalds if (current->total_link_count >= 40) 5961da177e4SLinus Torvalds goto loop; 5971da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 5981da177e4SLinus Torvalds cond_resched(); 59990ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 6001da177e4SLinus Torvalds if (err) 6011da177e4SLinus Torvalds goto loop; 6021da177e4SLinus Torvalds current->link_count++; 6031da177e4SLinus Torvalds current->total_link_count++; 6041da177e4SLinus Torvalds nd->depth++; 605cd4e91d3SAl Viro err = __do_follow_link(path, nd); 606258fa999SAl Viro path_put(path); 6071da177e4SLinus Torvalds current->link_count--; 6081da177e4SLinus Torvalds nd->depth--; 6091da177e4SLinus Torvalds return err; 6101da177e4SLinus Torvalds loop: 6111d957f9bSJan Blunck path_put_conditional(path, nd); 6121d957f9bSJan Blunck path_put(&nd->path); 6131da177e4SLinus Torvalds return err; 6141da177e4SLinus Torvalds } 6151da177e4SLinus Torvalds 616bab77ebfSAl Viro int follow_up(struct path *path) 6171da177e4SLinus Torvalds { 6181da177e4SLinus Torvalds struct vfsmount *parent; 6191da177e4SLinus Torvalds struct dentry *mountpoint; 6201da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 621bab77ebfSAl Viro parent = path->mnt->mnt_parent; 622bab77ebfSAl Viro if (parent == path->mnt) { 6231da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6241da177e4SLinus Torvalds return 0; 6251da177e4SLinus Torvalds } 6261da177e4SLinus Torvalds mntget(parent); 627bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 6281da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 629bab77ebfSAl Viro dput(path->dentry); 630bab77ebfSAl Viro path->dentry = mountpoint; 631bab77ebfSAl Viro mntput(path->mnt); 632bab77ebfSAl Viro path->mnt = parent; 6331da177e4SLinus Torvalds return 1; 6341da177e4SLinus Torvalds } 6351da177e4SLinus Torvalds 6361da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6371da177e4SLinus Torvalds * namespace.c 6381da177e4SLinus Torvalds */ 639463ffb2eSAl Viro static int __follow_mount(struct path *path) 640463ffb2eSAl Viro { 641463ffb2eSAl Viro int res = 0; 642463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 6431c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 644463ffb2eSAl Viro if (!mounted) 645463ffb2eSAl Viro break; 646463ffb2eSAl Viro dput(path->dentry); 647463ffb2eSAl Viro if (res) 648463ffb2eSAl Viro mntput(path->mnt); 649463ffb2eSAl Viro path->mnt = mounted; 650463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 651463ffb2eSAl Viro res = 1; 652463ffb2eSAl Viro } 653463ffb2eSAl Viro return res; 654463ffb2eSAl Viro } 655463ffb2eSAl Viro 65679ed0226SAl Viro static void follow_mount(struct path *path) 6571da177e4SLinus Torvalds { 65879ed0226SAl Viro while (d_mountpoint(path->dentry)) { 6591c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 6601da177e4SLinus Torvalds if (!mounted) 6611da177e4SLinus Torvalds break; 66279ed0226SAl Viro dput(path->dentry); 66379ed0226SAl Viro mntput(path->mnt); 66479ed0226SAl Viro path->mnt = mounted; 66579ed0226SAl Viro path->dentry = dget(mounted->mnt_root); 6661da177e4SLinus Torvalds } 6671da177e4SLinus Torvalds } 6681da177e4SLinus Torvalds 6691da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6701da177e4SLinus Torvalds * namespace.c 6711da177e4SLinus Torvalds */ 6729393bd07SAl Viro int follow_down(struct path *path) 6731da177e4SLinus Torvalds { 6741da177e4SLinus Torvalds struct vfsmount *mounted; 6751da177e4SLinus Torvalds 6761c755af4SAl Viro mounted = lookup_mnt(path); 6771da177e4SLinus Torvalds if (mounted) { 6789393bd07SAl Viro dput(path->dentry); 6799393bd07SAl Viro mntput(path->mnt); 6809393bd07SAl Viro path->mnt = mounted; 6819393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 6821da177e4SLinus Torvalds return 1; 6831da177e4SLinus Torvalds } 6841da177e4SLinus Torvalds return 0; 6851da177e4SLinus Torvalds } 6861da177e4SLinus Torvalds 687f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 6881da177e4SLinus Torvalds { 6892a737871SAl Viro set_root(nd); 690e518ddb7SAndreas Mohr 6911da177e4SLinus Torvalds while(1) { 6921da177e4SLinus Torvalds struct vfsmount *parent; 6934ac91378SJan Blunck struct dentry *old = nd->path.dentry; 6941da177e4SLinus Torvalds 6952a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 6962a737871SAl Viro nd->path.mnt == nd->root.mnt) { 6971da177e4SLinus Torvalds break; 6981da177e4SLinus Torvalds } 6991da177e4SLinus Torvalds spin_lock(&dcache_lock); 7004ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 7014ac91378SJan Blunck nd->path.dentry = dget(nd->path.dentry->d_parent); 7021da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7031da177e4SLinus Torvalds dput(old); 7041da177e4SLinus Torvalds break; 7051da177e4SLinus Torvalds } 7061da177e4SLinus Torvalds spin_unlock(&dcache_lock); 7071da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 7084ac91378SJan Blunck parent = nd->path.mnt->mnt_parent; 7094ac91378SJan Blunck if (parent == nd->path.mnt) { 7101da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7111da177e4SLinus Torvalds break; 7121da177e4SLinus Torvalds } 7131da177e4SLinus Torvalds mntget(parent); 7144ac91378SJan Blunck nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint); 7151da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 7161da177e4SLinus Torvalds dput(old); 7174ac91378SJan Blunck mntput(nd->path.mnt); 7184ac91378SJan Blunck nd->path.mnt = parent; 7191da177e4SLinus Torvalds } 72079ed0226SAl Viro follow_mount(&nd->path); 7211da177e4SLinus Torvalds } 7221da177e4SLinus Torvalds 7231da177e4SLinus Torvalds /* 7241da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 7251da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 7261da177e4SLinus Torvalds * It _is_ time-critical. 7271da177e4SLinus Torvalds */ 7281da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 7291da177e4SLinus Torvalds struct path *path) 7301da177e4SLinus Torvalds { 7314ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 7326e6b1bd1SAl Viro struct dentry *dentry, *parent; 7336e6b1bd1SAl Viro struct inode *dir; 7343cac260aSAl Viro /* 7353cac260aSAl Viro * See if the low-level filesystem might want 7363cac260aSAl Viro * to use its own hash.. 7373cac260aSAl Viro */ 7383cac260aSAl Viro if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 7393cac260aSAl Viro int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name); 7403cac260aSAl Viro if (err < 0) 7413cac260aSAl Viro return err; 7423cac260aSAl Viro } 7431da177e4SLinus Torvalds 7443cac260aSAl Viro dentry = __d_lookup(nd->path.dentry, name); 7451da177e4SLinus Torvalds if (!dentry) 7461da177e4SLinus Torvalds goto need_lookup; 7471da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 7481da177e4SLinus Torvalds goto need_revalidate; 7491da177e4SLinus Torvalds done: 7501da177e4SLinus Torvalds path->mnt = mnt; 7511da177e4SLinus Torvalds path->dentry = dentry; 752634ee701SAl Viro __follow_mount(path); 7531da177e4SLinus Torvalds return 0; 7541da177e4SLinus Torvalds 7551da177e4SLinus Torvalds need_lookup: 7566e6b1bd1SAl Viro parent = nd->path.dentry; 7576e6b1bd1SAl Viro dir = parent->d_inode; 7586e6b1bd1SAl Viro 7596e6b1bd1SAl Viro mutex_lock(&dir->i_mutex); 7606e6b1bd1SAl Viro /* 7616e6b1bd1SAl Viro * First re-do the cached lookup just in case it was created 7626e6b1bd1SAl Viro * while we waited for the directory semaphore.. 7636e6b1bd1SAl Viro * 7646e6b1bd1SAl Viro * FIXME! This could use version numbering or similar to 7656e6b1bd1SAl Viro * avoid unnecessary cache lookups. 7666e6b1bd1SAl Viro * 7676e6b1bd1SAl Viro * The "dcache_lock" is purely to protect the RCU list walker 7686e6b1bd1SAl Viro * from concurrent renames at this point (we mustn't get false 7696e6b1bd1SAl Viro * negatives from the RCU list walk here, unlike the optimistic 7706e6b1bd1SAl Viro * fast walk). 7716e6b1bd1SAl Viro * 7726e6b1bd1SAl Viro * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 7736e6b1bd1SAl Viro */ 7746e6b1bd1SAl Viro dentry = d_lookup(parent, name); 7756e6b1bd1SAl Viro if (!dentry) { 7766e6b1bd1SAl Viro struct dentry *new; 7776e6b1bd1SAl Viro 7786e6b1bd1SAl Viro /* Don't create child dentry for a dead directory. */ 7796e6b1bd1SAl Viro dentry = ERR_PTR(-ENOENT); 7806e6b1bd1SAl Viro if (IS_DEADDIR(dir)) 7816e6b1bd1SAl Viro goto out_unlock; 7826e6b1bd1SAl Viro 7836e6b1bd1SAl Viro new = d_alloc(parent, name); 7846e6b1bd1SAl Viro dentry = ERR_PTR(-ENOMEM); 7856e6b1bd1SAl Viro if (new) { 7866e6b1bd1SAl Viro dentry = dir->i_op->lookup(dir, new, nd); 7876e6b1bd1SAl Viro if (dentry) 7886e6b1bd1SAl Viro dput(new); 7896e6b1bd1SAl Viro else 7906e6b1bd1SAl Viro dentry = new; 7916e6b1bd1SAl Viro } 7926e6b1bd1SAl Viro out_unlock: 7936e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 7946e6b1bd1SAl Viro if (IS_ERR(dentry)) 7956e6b1bd1SAl Viro goto fail; 7966e6b1bd1SAl Viro goto done; 7976e6b1bd1SAl Viro } 7986e6b1bd1SAl Viro 7996e6b1bd1SAl Viro /* 8006e6b1bd1SAl Viro * Uhhuh! Nasty case: the cache was re-populated while 8016e6b1bd1SAl Viro * we waited on the semaphore. Need to revalidate. 8026e6b1bd1SAl Viro */ 8036e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 8046e6b1bd1SAl Viro if (dentry->d_op && dentry->d_op->d_revalidate) { 8056e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 8066e6b1bd1SAl Viro if (!dentry) 8076e6b1bd1SAl Viro dentry = ERR_PTR(-ENOENT); 8086e6b1bd1SAl Viro } 8091da177e4SLinus Torvalds if (IS_ERR(dentry)) 8101da177e4SLinus Torvalds goto fail; 8111da177e4SLinus Torvalds goto done; 8121da177e4SLinus Torvalds 8131da177e4SLinus Torvalds need_revalidate: 814bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 815bcdc5e01SIan Kent if (!dentry) 8161da177e4SLinus Torvalds goto need_lookup; 817bcdc5e01SIan Kent if (IS_ERR(dentry)) 818bcdc5e01SIan Kent goto fail; 819bcdc5e01SIan Kent goto done; 8201da177e4SLinus Torvalds 8211da177e4SLinus Torvalds fail: 8221da177e4SLinus Torvalds return PTR_ERR(dentry); 8231da177e4SLinus Torvalds } 8241da177e4SLinus Torvalds 8251da177e4SLinus Torvalds /* 826ac278a9cSAl Viro * This is a temporary kludge to deal with "automount" symlinks; proper 827ac278a9cSAl Viro * solution is to trigger them on follow_mount(), so that do_lookup() 828ac278a9cSAl Viro * would DTRT. To be killed before 2.6.34-final. 829ac278a9cSAl Viro */ 830ac278a9cSAl Viro static inline int follow_on_final(struct inode *inode, unsigned lookup_flags) 831ac278a9cSAl Viro { 832ac278a9cSAl Viro return inode && unlikely(inode->i_op->follow_link) && 833ac278a9cSAl Viro ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode)); 834ac278a9cSAl Viro } 835ac278a9cSAl Viro 836ac278a9cSAl Viro /* 8371da177e4SLinus Torvalds * Name resolution. 838ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 839ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8401da177e4SLinus Torvalds * 841ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 842ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8431da177e4SLinus Torvalds */ 8446de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 8451da177e4SLinus Torvalds { 8461da177e4SLinus Torvalds struct path next; 8471da177e4SLinus Torvalds struct inode *inode; 8481da177e4SLinus Torvalds int err; 8491da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8501da177e4SLinus Torvalds 8511da177e4SLinus Torvalds while (*name=='/') 8521da177e4SLinus Torvalds name++; 8531da177e4SLinus Torvalds if (!*name) 8541da177e4SLinus Torvalds goto return_reval; 8551da177e4SLinus Torvalds 8564ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8571da177e4SLinus Torvalds if (nd->depth) 858f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8591da177e4SLinus Torvalds 8601da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8611da177e4SLinus Torvalds for(;;) { 8621da177e4SLinus Torvalds unsigned long hash; 8631da177e4SLinus Torvalds struct qstr this; 8641da177e4SLinus Torvalds unsigned int c; 8651da177e4SLinus Torvalds 866cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 867b75b5086SAl Viro err = exec_permission(inode); 8681da177e4SLinus Torvalds if (err) 8691da177e4SLinus Torvalds break; 8701da177e4SLinus Torvalds 8711da177e4SLinus Torvalds this.name = name; 8721da177e4SLinus Torvalds c = *(const unsigned char *)name; 8731da177e4SLinus Torvalds 8741da177e4SLinus Torvalds hash = init_name_hash(); 8751da177e4SLinus Torvalds do { 8761da177e4SLinus Torvalds name++; 8771da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8781da177e4SLinus Torvalds c = *(const unsigned char *)name; 8791da177e4SLinus Torvalds } while (c && (c != '/')); 8801da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8811da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8821da177e4SLinus Torvalds 8831da177e4SLinus Torvalds /* remove trailing slashes? */ 8841da177e4SLinus Torvalds if (!c) 8851da177e4SLinus Torvalds goto last_component; 8861da177e4SLinus Torvalds while (*++name == '/'); 8871da177e4SLinus Torvalds if (!*name) 8881da177e4SLinus Torvalds goto last_with_slashes; 8891da177e4SLinus Torvalds 8901da177e4SLinus Torvalds /* 8911da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8921da177e4SLinus Torvalds * to be able to know about the current root directory and 8931da177e4SLinus Torvalds * parent relationships. 8941da177e4SLinus Torvalds */ 8951da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8961da177e4SLinus Torvalds default: 8971da177e4SLinus Torvalds break; 8981da177e4SLinus Torvalds case 2: 8991da177e4SLinus Torvalds if (this.name[1] != '.') 9001da177e4SLinus Torvalds break; 90158c465ebSAl Viro follow_dotdot(nd); 9024ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9031da177e4SLinus Torvalds /* fallthrough */ 9041da177e4SLinus Torvalds case 1: 9051da177e4SLinus Torvalds continue; 9061da177e4SLinus Torvalds } 9071da177e4SLinus Torvalds /* This does the actual lookups.. */ 9081da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9091da177e4SLinus Torvalds if (err) 9101da177e4SLinus Torvalds break; 9111da177e4SLinus Torvalds 9121da177e4SLinus Torvalds err = -ENOENT; 9131da177e4SLinus Torvalds inode = next.dentry->d_inode; 9141da177e4SLinus Torvalds if (!inode) 9151da177e4SLinus Torvalds goto out_dput; 9161da177e4SLinus Torvalds 9171da177e4SLinus Torvalds if (inode->i_op->follow_link) { 91890ebe565SAl Viro err = do_follow_link(&next, nd); 9191da177e4SLinus Torvalds if (err) 9201da177e4SLinus Torvalds goto return_err; 9211da177e4SLinus Torvalds err = -ENOENT; 9224ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9231da177e4SLinus Torvalds if (!inode) 9241da177e4SLinus Torvalds break; 92509dd17d3SMiklos Szeredi } else 92609dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9271da177e4SLinus Torvalds err = -ENOTDIR; 9281da177e4SLinus Torvalds if (!inode->i_op->lookup) 9291da177e4SLinus Torvalds break; 9301da177e4SLinus Torvalds continue; 9311da177e4SLinus Torvalds /* here ends the main loop */ 9321da177e4SLinus Torvalds 9331da177e4SLinus Torvalds last_with_slashes: 9341da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9351da177e4SLinus Torvalds last_component: 936f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 937f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9381da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9391da177e4SLinus Torvalds goto lookup_parent; 9401da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9411da177e4SLinus Torvalds default: 9421da177e4SLinus Torvalds break; 9431da177e4SLinus Torvalds case 2: 9441da177e4SLinus Torvalds if (this.name[1] != '.') 9451da177e4SLinus Torvalds break; 94658c465ebSAl Viro follow_dotdot(nd); 9474ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9481da177e4SLinus Torvalds /* fallthrough */ 9491da177e4SLinus Torvalds case 1: 9501da177e4SLinus Torvalds goto return_reval; 9511da177e4SLinus Torvalds } 9521da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9531da177e4SLinus Torvalds if (err) 9541da177e4SLinus Torvalds break; 9551da177e4SLinus Torvalds inode = next.dentry->d_inode; 956ac278a9cSAl Viro if (follow_on_final(inode, lookup_flags)) { 95790ebe565SAl Viro err = do_follow_link(&next, nd); 9581da177e4SLinus Torvalds if (err) 9591da177e4SLinus Torvalds goto return_err; 9604ac91378SJan Blunck inode = nd->path.dentry->d_inode; 96109dd17d3SMiklos Szeredi } else 96209dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9631da177e4SLinus Torvalds err = -ENOENT; 9641da177e4SLinus Torvalds if (!inode) 9651da177e4SLinus Torvalds break; 9661da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9671da177e4SLinus Torvalds err = -ENOTDIR; 968acfa4380SAl Viro if (!inode->i_op->lookup) 9691da177e4SLinus Torvalds break; 9701da177e4SLinus Torvalds } 9711da177e4SLinus Torvalds goto return_base; 9721da177e4SLinus Torvalds lookup_parent: 9731da177e4SLinus Torvalds nd->last = this; 9741da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9751da177e4SLinus Torvalds if (this.name[0] != '.') 9761da177e4SLinus Torvalds goto return_base; 9771da177e4SLinus Torvalds if (this.len == 1) 9781da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9791da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9801da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9811da177e4SLinus Torvalds else 9821da177e4SLinus Torvalds goto return_base; 9831da177e4SLinus Torvalds return_reval: 9841da177e4SLinus Torvalds /* 9851da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 9861da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 9871da177e4SLinus Torvalds */ 9884ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 9894ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 9901da177e4SLinus Torvalds err = -ESTALE; 9911da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 9924ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 9934ac91378SJan Blunck nd->path.dentry, nd)) 9941da177e4SLinus Torvalds break; 9951da177e4SLinus Torvalds } 9961da177e4SLinus Torvalds return_base: 9971da177e4SLinus Torvalds return 0; 9981da177e4SLinus Torvalds out_dput: 9991d957f9bSJan Blunck path_put_conditional(&next, nd); 10001da177e4SLinus Torvalds break; 10011da177e4SLinus Torvalds } 10021d957f9bSJan Blunck path_put(&nd->path); 10031da177e4SLinus Torvalds return_err: 10041da177e4SLinus Torvalds return err; 10051da177e4SLinus Torvalds } 10061da177e4SLinus Torvalds 1007fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 10081da177e4SLinus Torvalds { 10096de88d72SAl Viro struct path save = nd->path; 10106de88d72SAl Viro int result; 10116de88d72SAl Viro 10121da177e4SLinus Torvalds current->total_link_count = 0; 10136de88d72SAl Viro 10146de88d72SAl Viro /* make sure the stuff we saved doesn't go away */ 10156de88d72SAl Viro path_get(&save); 10166de88d72SAl Viro 10176de88d72SAl Viro result = link_path_walk(name, nd); 10186de88d72SAl Viro if (result == -ESTALE) { 10196de88d72SAl Viro /* nd->path had been dropped */ 10206de88d72SAl Viro current->total_link_count = 0; 10216de88d72SAl Viro nd->path = save; 10226de88d72SAl Viro path_get(&nd->path); 10236de88d72SAl Viro nd->flags |= LOOKUP_REVAL; 10246de88d72SAl Viro result = link_path_walk(name, nd); 10256de88d72SAl Viro } 10266de88d72SAl Viro 10276de88d72SAl Viro path_put(&save); 10286de88d72SAl Viro 10296de88d72SAl Viro return result; 10301da177e4SLinus Torvalds } 10311da177e4SLinus Torvalds 10329b4a9b14SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 10331da177e4SLinus Torvalds { 1034ea3834d9SPrasanna Meda int retval = 0; 1035170aa3d0SUlrich Drepper int fput_needed; 1036170aa3d0SUlrich Drepper struct file *file; 10371da177e4SLinus Torvalds 10381da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10391da177e4SLinus Torvalds nd->flags = flags; 10401da177e4SLinus Torvalds nd->depth = 0; 10412a737871SAl Viro nd->root.mnt = NULL; 10421da177e4SLinus Torvalds 10431da177e4SLinus Torvalds if (*name=='/') { 10442a737871SAl Viro set_root(nd); 10452a737871SAl Viro nd->path = nd->root; 10462a737871SAl Viro path_get(&nd->root); 10475590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 10482a737871SAl Viro struct fs_struct *fs = current->fs; 1049e518ddb7SAndreas Mohr read_lock(&fs->lock); 10506ac08c39SJan Blunck nd->path = fs->pwd; 10516ac08c39SJan Blunck path_get(&fs->pwd); 1052e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10535590ff0dSUlrich Drepper } else { 10545590ff0dSUlrich Drepper struct dentry *dentry; 10555590ff0dSUlrich Drepper 10565590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10575590ff0dSUlrich Drepper retval = -EBADF; 1058170aa3d0SUlrich Drepper if (!file) 10596d09bb62STrond Myklebust goto out_fail; 10605590ff0dSUlrich Drepper 10610f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10625590ff0dSUlrich Drepper 10635590ff0dSUlrich Drepper retval = -ENOTDIR; 1064170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10656d09bb62STrond Myklebust goto fput_fail; 10665590ff0dSUlrich Drepper 10675590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1068170aa3d0SUlrich Drepper if (retval) 10696d09bb62STrond Myklebust goto fput_fail; 10705590ff0dSUlrich Drepper 10715dd784d0SJan Blunck nd->path = file->f_path; 10725dd784d0SJan Blunck path_get(&file->f_path); 10735590ff0dSUlrich Drepper 10745590ff0dSUlrich Drepper fput_light(file, fput_needed); 10751da177e4SLinus Torvalds } 10769b4a9b14SAl Viro return 0; 10772dfdd266SJosef 'Jeff' Sipek 10789b4a9b14SAl Viro fput_fail: 10799b4a9b14SAl Viro fput_light(file, fput_needed); 10809b4a9b14SAl Viro out_fail: 10819b4a9b14SAl Viro return retval; 10829b4a9b14SAl Viro } 10839b4a9b14SAl Viro 10849b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 10859b4a9b14SAl Viro static int do_path_lookup(int dfd, const char *name, 10869b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 10879b4a9b14SAl Viro { 10889b4a9b14SAl Viro int retval = path_init(dfd, name, flags, nd); 10899b4a9b14SAl Viro if (!retval) 10902dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10914ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10924ac91378SJan Blunck nd->path.dentry->d_inode)) 10934ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10942a737871SAl Viro if (nd->root.mnt) { 10952a737871SAl Viro path_put(&nd->root); 10962a737871SAl Viro nd->root.mnt = NULL; 10972a737871SAl Viro } 1098170aa3d0SUlrich Drepper return retval; 10991da177e4SLinus Torvalds } 11001da177e4SLinus Torvalds 1101fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 11025590ff0dSUlrich Drepper struct nameidata *nd) 11035590ff0dSUlrich Drepper { 11045590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 11055590ff0dSUlrich Drepper } 11065590ff0dSUlrich Drepper 1107d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1108d1811465SAl Viro { 1109d1811465SAl Viro struct nameidata nd; 1110d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1111d1811465SAl Viro if (!res) 1112d1811465SAl Viro *path = nd.path; 1113d1811465SAl Viro return res; 1114d1811465SAl Viro } 1115d1811465SAl Viro 111616f18200SJosef 'Jeff' Sipek /** 111716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 111816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 111916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 112016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 112116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 112216f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 112316f18200SJosef 'Jeff' Sipek */ 112416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 112516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 112616f18200SJosef 'Jeff' Sipek struct nameidata *nd) 112716f18200SJosef 'Jeff' Sipek { 112816f18200SJosef 'Jeff' Sipek int retval; 112916f18200SJosef 'Jeff' Sipek 113016f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 113116f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 113216f18200SJosef 'Jeff' Sipek nd->flags = flags; 113316f18200SJosef 'Jeff' Sipek nd->depth = 0; 113416f18200SJosef 'Jeff' Sipek 1135c8e7f449SJan Blunck nd->path.dentry = dentry; 1136c8e7f449SJan Blunck nd->path.mnt = mnt; 1137c8e7f449SJan Blunck path_get(&nd->path); 11385b857119SAl Viro nd->root = nd->path; 11395b857119SAl Viro path_get(&nd->root); 114016f18200SJosef 'Jeff' Sipek 114116f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11424ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11434ac91378SJan Blunck nd->path.dentry->d_inode)) 11444ac91378SJan Blunck audit_inode(name, nd->path.dentry); 114516f18200SJosef 'Jeff' Sipek 11462a737871SAl Viro path_put(&nd->root); 11472a737871SAl Viro nd->root.mnt = NULL; 114816f18200SJosef 'Jeff' Sipek 11492a737871SAl Viro return retval; 115016f18200SJosef 'Jeff' Sipek } 115116f18200SJosef 'Jeff' Sipek 1152eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1153eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 11541da177e4SLinus Torvalds { 11551da177e4SLinus Torvalds struct dentry *dentry; 11561da177e4SLinus Torvalds struct inode *inode; 11571da177e4SLinus Torvalds int err; 11581da177e4SLinus Torvalds 11591da177e4SLinus Torvalds inode = base->d_inode; 11601da177e4SLinus Torvalds 11611da177e4SLinus Torvalds /* 11621da177e4SLinus Torvalds * See if the low-level filesystem might want 11631da177e4SLinus Torvalds * to use its own hash.. 11641da177e4SLinus Torvalds */ 11651da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 11661da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 11671da177e4SLinus Torvalds dentry = ERR_PTR(err); 11681da177e4SLinus Torvalds if (err < 0) 11691da177e4SLinus Torvalds goto out; 11701da177e4SLinus Torvalds } 11711da177e4SLinus Torvalds 11726e6b1bd1SAl Viro dentry = __d_lookup(base, name); 11736e6b1bd1SAl Viro 11746e6b1bd1SAl Viro /* lockess __d_lookup may fail due to concurrent d_move() 11756e6b1bd1SAl Viro * in some unrelated directory, so try with d_lookup 11766e6b1bd1SAl Viro */ 11776e6b1bd1SAl Viro if (!dentry) 11786e6b1bd1SAl Viro dentry = d_lookup(base, name); 11796e6b1bd1SAl Viro 11806e6b1bd1SAl Viro if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 11816e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 11826e6b1bd1SAl Viro 11831da177e4SLinus Torvalds if (!dentry) { 1184d70b67c8SMiklos Szeredi struct dentry *new; 1185d70b67c8SMiklos Szeredi 1186d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1187d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1188d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1189d70b67c8SMiklos Szeredi goto out; 1190d70b67c8SMiklos Szeredi 1191d70b67c8SMiklos Szeredi new = d_alloc(base, name); 11921da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 11931da177e4SLinus Torvalds if (!new) 11941da177e4SLinus Torvalds goto out; 11951da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 11961da177e4SLinus Torvalds if (!dentry) 11971da177e4SLinus Torvalds dentry = new; 11981da177e4SLinus Torvalds else 11991da177e4SLinus Torvalds dput(new); 12001da177e4SLinus Torvalds } 12011da177e4SLinus Torvalds out: 12021da177e4SLinus Torvalds return dentry; 12031da177e4SLinus Torvalds } 12041da177e4SLinus Torvalds 1205057f6c01SJames Morris /* 1206057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1207057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1208057f6c01SJames Morris * SMP-safe. 1209057f6c01SJames Morris */ 1210a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 12111da177e4SLinus Torvalds { 1212eead1911SChristoph Hellwig int err; 1213eead1911SChristoph Hellwig 1214b75b5086SAl Viro err = exec_permission(nd->path.dentry->d_inode); 1215eead1911SChristoph Hellwig if (err) 1216eead1911SChristoph Hellwig return ERR_PTR(err); 12174ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 12181da177e4SLinus Torvalds } 12191da177e4SLinus Torvalds 1220eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1221eead1911SChristoph Hellwig struct dentry *base, int len) 12221da177e4SLinus Torvalds { 12231da177e4SLinus Torvalds unsigned long hash; 12241da177e4SLinus Torvalds unsigned int c; 12251da177e4SLinus Torvalds 1226057f6c01SJames Morris this->name = name; 1227057f6c01SJames Morris this->len = len; 12281da177e4SLinus Torvalds if (!len) 1229057f6c01SJames Morris return -EACCES; 12301da177e4SLinus Torvalds 12311da177e4SLinus Torvalds hash = init_name_hash(); 12321da177e4SLinus Torvalds while (len--) { 12331da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12341da177e4SLinus Torvalds if (c == '/' || c == '\0') 1235057f6c01SJames Morris return -EACCES; 12361da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12371da177e4SLinus Torvalds } 1238057f6c01SJames Morris this->hash = end_name_hash(hash); 1239057f6c01SJames Morris return 0; 1240057f6c01SJames Morris } 12411da177e4SLinus Torvalds 1242eead1911SChristoph Hellwig /** 1243a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1244eead1911SChristoph Hellwig * @name: pathname component to lookup 1245eead1911SChristoph Hellwig * @base: base directory to lookup from 1246eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1247eead1911SChristoph Hellwig * 1248a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1249a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1250eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1251eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1252eead1911SChristoph Hellwig */ 1253057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1254057f6c01SJames Morris { 1255057f6c01SJames Morris int err; 1256057f6c01SJames Morris struct qstr this; 1257057f6c01SJames Morris 12582f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 12592f9092e1SDavid Woodhouse 1260057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1261057f6c01SJames Morris if (err) 1262057f6c01SJames Morris return ERR_PTR(err); 1263eead1911SChristoph Hellwig 1264b75b5086SAl Viro err = exec_permission(base->d_inode); 1265eead1911SChristoph Hellwig if (err) 1266eead1911SChristoph Hellwig return ERR_PTR(err); 126749705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1268057f6c01SJames Morris } 1269057f6c01SJames Morris 12702d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 12712d8f3038SAl Viro struct path *path) 12721da177e4SLinus Torvalds { 12732d8f3038SAl Viro struct nameidata nd; 12741da177e4SLinus Torvalds char *tmp = getname(name); 12751da177e4SLinus Torvalds int err = PTR_ERR(tmp); 12761da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 12772d8f3038SAl Viro 12782d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 12792d8f3038SAl Viro 12802d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 12811da177e4SLinus Torvalds putname(tmp); 12822d8f3038SAl Viro if (!err) 12832d8f3038SAl Viro *path = nd.path; 12841da177e4SLinus Torvalds } 12851da177e4SLinus Torvalds return err; 12861da177e4SLinus Torvalds } 12871da177e4SLinus Torvalds 12882ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 12892ad94ae6SAl Viro struct nameidata *nd, char **name) 12902ad94ae6SAl Viro { 12912ad94ae6SAl Viro char *s = getname(path); 12922ad94ae6SAl Viro int error; 12932ad94ae6SAl Viro 12942ad94ae6SAl Viro if (IS_ERR(s)) 12952ad94ae6SAl Viro return PTR_ERR(s); 12962ad94ae6SAl Viro 12972ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 12982ad94ae6SAl Viro if (error) 12992ad94ae6SAl Viro putname(s); 13002ad94ae6SAl Viro else 13012ad94ae6SAl Viro *name = s; 13022ad94ae6SAl Viro 13032ad94ae6SAl Viro return error; 13042ad94ae6SAl Viro } 13052ad94ae6SAl Viro 13061da177e4SLinus Torvalds /* 13071da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 13081da177e4SLinus Torvalds * minimal. 13091da177e4SLinus Torvalds */ 13101da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 13111da177e4SLinus Torvalds { 1312da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1313da9592edSDavid Howells 13141da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 13151da177e4SLinus Torvalds return 0; 1316da9592edSDavid Howells if (inode->i_uid == fsuid) 13171da177e4SLinus Torvalds return 0; 1318da9592edSDavid Howells if (dir->i_uid == fsuid) 13191da177e4SLinus Torvalds return 0; 13201da177e4SLinus Torvalds return !capable(CAP_FOWNER); 13211da177e4SLinus Torvalds } 13221da177e4SLinus Torvalds 13231da177e4SLinus Torvalds /* 13241da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 13251da177e4SLinus Torvalds * whether the type of victim is right. 13261da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 13271da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 13281da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 13291da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13301da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13311da177e4SLinus Torvalds * a. be owner of dir, or 13321da177e4SLinus Torvalds * b. be owner of victim, or 13331da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13341da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 13351da177e4SLinus Torvalds * links pointing to it. 13361da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 13371da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 13381da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 13391da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 13401da177e4SLinus Torvalds * nfs_async_unlink(). 13411da177e4SLinus Torvalds */ 1342858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 13431da177e4SLinus Torvalds { 13441da177e4SLinus Torvalds int error; 13451da177e4SLinus Torvalds 13461da177e4SLinus Torvalds if (!victim->d_inode) 13471da177e4SLinus Torvalds return -ENOENT; 13481da177e4SLinus Torvalds 13491da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 13505a190ae6SAl Viro audit_inode_child(victim->d_name.name, victim, dir); 13511da177e4SLinus Torvalds 1352f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 13531da177e4SLinus Torvalds if (error) 13541da177e4SLinus Torvalds return error; 13551da177e4SLinus Torvalds if (IS_APPEND(dir)) 13561da177e4SLinus Torvalds return -EPERM; 13571da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1358f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 13591da177e4SLinus Torvalds return -EPERM; 13601da177e4SLinus Torvalds if (isdir) { 13611da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 13621da177e4SLinus Torvalds return -ENOTDIR; 13631da177e4SLinus Torvalds if (IS_ROOT(victim)) 13641da177e4SLinus Torvalds return -EBUSY; 13651da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 13661da177e4SLinus Torvalds return -EISDIR; 13671da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13681da177e4SLinus Torvalds return -ENOENT; 13691da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 13701da177e4SLinus Torvalds return -EBUSY; 13711da177e4SLinus Torvalds return 0; 13721da177e4SLinus Torvalds } 13731da177e4SLinus Torvalds 13741da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 13751da177e4SLinus Torvalds * dir. 13761da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 13771da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 13781da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 13791da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 13801da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 13811da177e4SLinus Torvalds */ 1382a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 13831da177e4SLinus Torvalds { 13841da177e4SLinus Torvalds if (child->d_inode) 13851da177e4SLinus Torvalds return -EEXIST; 13861da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13871da177e4SLinus Torvalds return -ENOENT; 1388f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 13891da177e4SLinus Torvalds } 13901da177e4SLinus Torvalds 13911da177e4SLinus Torvalds /* 13921da177e4SLinus Torvalds * O_DIRECTORY translates into forcing a directory lookup. 13931da177e4SLinus Torvalds */ 13941da177e4SLinus Torvalds static inline int lookup_flags(unsigned int f) 13951da177e4SLinus Torvalds { 13961da177e4SLinus Torvalds unsigned long retval = LOOKUP_FOLLOW; 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds if (f & O_NOFOLLOW) 13991da177e4SLinus Torvalds retval &= ~LOOKUP_FOLLOW; 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds if (f & O_DIRECTORY) 14021da177e4SLinus Torvalds retval |= LOOKUP_DIRECTORY; 14031da177e4SLinus Torvalds 14041da177e4SLinus Torvalds return retval; 14051da177e4SLinus Torvalds } 14061da177e4SLinus Torvalds 14071da177e4SLinus Torvalds /* 14081da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 14091da177e4SLinus Torvalds */ 14101da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 14111da177e4SLinus Torvalds { 14121da177e4SLinus Torvalds struct dentry *p; 14131da177e4SLinus Torvalds 14141da177e4SLinus Torvalds if (p1 == p2) { 1415f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 14161da177e4SLinus Torvalds return NULL; 14171da177e4SLinus Torvalds } 14181da177e4SLinus Torvalds 1419a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14201da177e4SLinus Torvalds 1421e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1422e2761a11SOGAWA Hirofumi if (p) { 1423f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1424f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 14251da177e4SLinus Torvalds return p; 14261da177e4SLinus Torvalds } 14271da177e4SLinus Torvalds 1428e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1429e2761a11SOGAWA Hirofumi if (p) { 1430f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1431f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14321da177e4SLinus Torvalds return p; 14331da177e4SLinus Torvalds } 14341da177e4SLinus Torvalds 1435f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1436f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 14371da177e4SLinus Torvalds return NULL; 14381da177e4SLinus Torvalds } 14391da177e4SLinus Torvalds 14401da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 14411da177e4SLinus Torvalds { 14421b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 14431da177e4SLinus Torvalds if (p1 != p2) { 14441b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1445a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14461da177e4SLinus Torvalds } 14471da177e4SLinus Torvalds } 14481da177e4SLinus Torvalds 14491da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 14501da177e4SLinus Torvalds struct nameidata *nd) 14511da177e4SLinus Torvalds { 1452a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 14531da177e4SLinus Torvalds 14541da177e4SLinus Torvalds if (error) 14551da177e4SLinus Torvalds return error; 14561da177e4SLinus Torvalds 1457acfa4380SAl Viro if (!dir->i_op->create) 14581da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 14591da177e4SLinus Torvalds mode &= S_IALLUGO; 14601da177e4SLinus Torvalds mode |= S_IFREG; 14611da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 14621da177e4SLinus Torvalds if (error) 14631da177e4SLinus Torvalds return error; 14649e3509e2SJan Kara vfs_dq_init(dir); 14651da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1466a74574aaSStephen Smalley if (!error) 1467f38aa942SAmy Griffis fsnotify_create(dir, dentry); 14681da177e4SLinus Torvalds return error; 14691da177e4SLinus Torvalds } 14701da177e4SLinus Torvalds 14713fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 14721da177e4SLinus Torvalds { 14733fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 14741da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 14751da177e4SLinus Torvalds int error; 14761da177e4SLinus Torvalds 14771da177e4SLinus Torvalds if (!inode) 14781da177e4SLinus Torvalds return -ENOENT; 14791da177e4SLinus Torvalds 1480c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1481c8fe8f30SChristoph Hellwig case S_IFLNK: 14821da177e4SLinus Torvalds return -ELOOP; 1483c8fe8f30SChristoph Hellwig case S_IFDIR: 1484c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 14851da177e4SLinus Torvalds return -EISDIR; 1486c8fe8f30SChristoph Hellwig break; 1487c8fe8f30SChristoph Hellwig case S_IFBLK: 1488c8fe8f30SChristoph Hellwig case S_IFCHR: 14893fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 14901da177e4SLinus Torvalds return -EACCES; 1491c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1492c8fe8f30SChristoph Hellwig case S_IFIFO: 1493c8fe8f30SChristoph Hellwig case S_IFSOCK: 14941da177e4SLinus Torvalds flag &= ~O_TRUNC; 1495c8fe8f30SChristoph Hellwig break; 14964a3fd211SDave Hansen } 1497b41572e9SDave Hansen 14983fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1499b41572e9SDave Hansen if (error) 1500b41572e9SDave Hansen return error; 15016146f0d5SMimi Zohar 15021da177e4SLinus Torvalds /* 15031da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 15041da177e4SLinus Torvalds */ 15051da177e4SLinus Torvalds if (IS_APPEND(inode)) { 15068737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 15077715b521SAl Viro return -EPERM; 15081da177e4SLinus Torvalds if (flag & O_TRUNC) 15097715b521SAl Viro return -EPERM; 15101da177e4SLinus Torvalds } 15111da177e4SLinus Torvalds 15121da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 15137715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 15147715b521SAl Viro return -EPERM; 15151da177e4SLinus Torvalds 15161da177e4SLinus Torvalds /* 15171da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 15181da177e4SLinus Torvalds */ 1519b65a9cfcSAl Viro return break_lease(inode, flag); 15207715b521SAl Viro } 15217715b521SAl Viro 15227715b521SAl Viro static int handle_truncate(struct path *path) 15237715b521SAl Viro { 15247715b521SAl Viro struct inode *inode = path->dentry->d_inode; 15257715b521SAl Viro int error = get_write_access(inode); 15261da177e4SLinus Torvalds if (error) 15277715b521SAl Viro return error; 15281da177e4SLinus Torvalds /* 15291da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 15301da177e4SLinus Torvalds */ 15311da177e4SLinus Torvalds error = locks_verify_locked(inode); 1532be6d3e56SKentaro Takeda if (!error) 15333fb64190SChristoph Hellwig error = security_path_truncate(path, 0, 1534be6d3e56SKentaro Takeda ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); 15351da177e4SLinus Torvalds if (!error) { 15367715b521SAl Viro error = do_truncate(path->dentry, 0, 1537d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1538d139d7ffSMiklos Szeredi NULL); 15391da177e4SLinus Torvalds } 15401da177e4SLinus Torvalds put_write_access(inode); 1541acd0c935SMimi Zohar return error; 15421da177e4SLinus Torvalds } 15431da177e4SLinus Torvalds 1544d57999e1SDave Hansen /* 1545d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1546d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1547d57999e1SDave Hansen * what get passed to sys_open(). 1548d57999e1SDave Hansen */ 1549d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 15508737c930SAl Viro int open_flag, int mode) 1551aab520e2SDave Hansen { 1552aab520e2SDave Hansen int error; 15534ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1554aab520e2SDave Hansen 1555aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1556ce3b0f8dSAl Viro mode &= ~current_umask(); 1557be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1558be6d3e56SKentaro Takeda if (error) 1559be6d3e56SKentaro Takeda goto out_unlock; 1560aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1561be6d3e56SKentaro Takeda out_unlock: 1562aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 15634ac91378SJan Blunck dput(nd->path.dentry); 15644ac91378SJan Blunck nd->path.dentry = path->dentry; 1565aab520e2SDave Hansen if (error) 1566aab520e2SDave Hansen return error; 1567aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 15688737c930SAl Viro return may_open(&nd->path, 0, open_flag & ~O_TRUNC); 1569aab520e2SDave Hansen } 1570aab520e2SDave Hansen 15711da177e4SLinus Torvalds /* 1572d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1573d57999e1SDave Hansen * 00 - read-only 1574d57999e1SDave Hansen * 01 - write-only 1575d57999e1SDave Hansen * 10 - read-write 1576d57999e1SDave Hansen * 11 - special 1577d57999e1SDave Hansen * it is changed into 1578d57999e1SDave Hansen * 00 - no permissions needed 1579d57999e1SDave Hansen * 01 - read-permission 1580d57999e1SDave Hansen * 10 - write-permission 1581d57999e1SDave Hansen * 11 - read-write 1582d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1583d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1584d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1585d57999e1SDave Hansen * later). 1586d57999e1SDave Hansen * 1587d57999e1SDave Hansen */ 1588d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1589d57999e1SDave Hansen { 1590d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1591d57999e1SDave Hansen flag++; 1592d57999e1SDave Hansen return flag; 1593d57999e1SDave Hansen } 1594d57999e1SDave Hansen 15957715b521SAl Viro static int open_will_truncate(int flag, struct inode *inode) 15964a3fd211SDave Hansen { 1597d57999e1SDave Hansen /* 15984a3fd211SDave Hansen * We'll never write to the fs underlying 15994a3fd211SDave Hansen * a device file. 16004a3fd211SDave Hansen */ 16014a3fd211SDave Hansen if (special_file(inode->i_mode)) 16024a3fd211SDave Hansen return 0; 16034a3fd211SDave Hansen return (flag & O_TRUNC); 16044a3fd211SDave Hansen } 16054a3fd211SDave Hansen 16064a3fd211SDave Hansen /* 16074a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 16084a3fd211SDave Hansen * are not the same as in the local variable "flag". See 16094a3fd211SDave Hansen * open_to_namei_flags() for more details. 16101da177e4SLinus Torvalds */ 1611a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 16126e8341a1SAl Viro int open_flag, int mode, int acc_mode) 16131da177e4SLinus Torvalds { 16144a3fd211SDave Hansen struct file *filp; 1615a70e65dfSChristoph Hellwig struct nameidata nd; 16166e8341a1SAl Viro int error; 16179850c056SAl Viro struct path path; 16181da177e4SLinus Torvalds struct dentry *dir; 16191da177e4SLinus Torvalds int count = 0; 16207715b521SAl Viro int will_truncate; 1621d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 16229850c056SAl Viro int force_reval = 0; 16231da177e4SLinus Torvalds 16246b2f3d1fSChristoph Hellwig /* 16256b2f3d1fSChristoph Hellwig * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only 16266b2f3d1fSChristoph Hellwig * check for O_DSYNC if the need any syncing at all we enforce it's 16276b2f3d1fSChristoph Hellwig * always set instead of having to deal with possibly weird behaviour 16286b2f3d1fSChristoph Hellwig * for malicious applications setting only __O_SYNC. 16296b2f3d1fSChristoph Hellwig */ 16306b2f3d1fSChristoph Hellwig if (open_flag & __O_SYNC) 16316b2f3d1fSChristoph Hellwig open_flag |= O_DSYNC; 16326b2f3d1fSChristoph Hellwig 16336e8341a1SAl Viro if (!acc_mode) 16346d125529SAl Viro acc_mode = MAY_OPEN | ACC_MODE(open_flag); 16351da177e4SLinus Torvalds 1636834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 1637834f2a4aSTrond Myklebust if (flag & O_TRUNC) 1638834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1639834f2a4aSTrond Myklebust 16401da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 16411da177e4SLinus Torvalds access from general write access. */ 16421da177e4SLinus Torvalds if (flag & O_APPEND) 16431da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 16441da177e4SLinus Torvalds 16451da177e4SLinus Torvalds /* 16461da177e4SLinus Torvalds * The simplest case - just a plain lookup. 16471da177e4SLinus Torvalds */ 16481da177e4SLinus Torvalds if (!(flag & O_CREAT)) { 16492dd6d1f4SAl Viro filp = get_empty_filp(); 16502dd6d1f4SAl Viro 16512dd6d1f4SAl Viro if (filp == NULL) 16522dd6d1f4SAl Viro return ERR_PTR(-ENFILE); 16532dd6d1f4SAl Viro nd.intent.open.file = filp; 1654482928d5SAl Viro filp->f_flags = open_flag; 16552dd6d1f4SAl Viro nd.intent.open.flags = flag; 16562dd6d1f4SAl Viro nd.intent.open.create_mode = 0; 16572dd6d1f4SAl Viro error = do_path_lookup(dfd, pathname, 16582dd6d1f4SAl Viro lookup_flags(flag)|LOOKUP_OPEN, &nd); 16592dd6d1f4SAl Viro if (IS_ERR(nd.intent.open.file)) { 16602dd6d1f4SAl Viro if (error == 0) { 16612dd6d1f4SAl Viro error = PTR_ERR(nd.intent.open.file); 16622dd6d1f4SAl Viro path_put(&nd.path); 16632dd6d1f4SAl Viro } 16642dd6d1f4SAl Viro } else if (error) 16652dd6d1f4SAl Viro release_open_intent(&nd); 16661da177e4SLinus Torvalds if (error) 1667a70e65dfSChristoph Hellwig return ERR_PTR(error); 16681da177e4SLinus Torvalds goto ok; 16691da177e4SLinus Torvalds } 16701da177e4SLinus Torvalds 16711da177e4SLinus Torvalds /* 16721da177e4SLinus Torvalds * Create - we need to know the parent. 16731da177e4SLinus Torvalds */ 16749850c056SAl Viro reval: 16759b4a9b14SAl Viro error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); 16761da177e4SLinus Torvalds if (error) 1677a70e65dfSChristoph Hellwig return ERR_PTR(error); 16789850c056SAl Viro if (force_reval) 16799850c056SAl Viro nd.flags |= LOOKUP_REVAL; 16809b4a9b14SAl Viro error = path_walk(pathname, &nd); 1681654f562cSJ. R. Okajima if (error) { 1682654f562cSJ. R. Okajima if (nd.root.mnt) 1683654f562cSJ. R. Okajima path_put(&nd.root); 16849b4a9b14SAl Viro return ERR_PTR(error); 1685654f562cSJ. R. Okajima } 16869b4a9b14SAl Viro if (unlikely(!audit_dummy_context())) 16879b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 16881da177e4SLinus Torvalds 16891da177e4SLinus Torvalds /* 16901da177e4SLinus Torvalds * We have the parent and last component. First of all, check 16911da177e4SLinus Torvalds * that we are not asked to creat(2) an obvious directory - that 16921da177e4SLinus Torvalds * will not do. 16931da177e4SLinus Torvalds */ 16941da177e4SLinus Torvalds error = -EISDIR; 1695a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len]) 16968737f3a1SAl Viro goto exit_parent; 16971da177e4SLinus Torvalds 16988737f3a1SAl Viro error = -ENFILE; 16998737f3a1SAl Viro filp = get_empty_filp(); 17008737f3a1SAl Viro if (filp == NULL) 17018737f3a1SAl Viro goto exit_parent; 17028737f3a1SAl Viro nd.intent.open.file = filp; 1703482928d5SAl Viro filp->f_flags = open_flag; 17048737f3a1SAl Viro nd.intent.open.flags = flag; 17058737f3a1SAl Viro nd.intent.open.create_mode = mode; 1706a70e65dfSChristoph Hellwig dir = nd.path.dentry; 1707a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 17088737f3a1SAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN; 17093516586aSAl Viro if (flag & O_EXCL) 17103516586aSAl Viro nd.flags |= LOOKUP_EXCL; 17111b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1712a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1713a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 17141da177e4SLinus Torvalds 17151da177e4SLinus Torvalds do_last: 17164e7506e4SAl Viro error = PTR_ERR(path.dentry); 17174e7506e4SAl Viro if (IS_ERR(path.dentry)) { 17181b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17191da177e4SLinus Torvalds goto exit; 17201da177e4SLinus Torvalds } 17211da177e4SLinus Torvalds 1722a70e65dfSChristoph Hellwig if (IS_ERR(nd.intent.open.file)) { 1723a70e65dfSChristoph Hellwig error = PTR_ERR(nd.intent.open.file); 17244a3fd211SDave Hansen goto exit_mutex_unlock; 17254af4c52fSOleg Drokin } 17264af4c52fSOleg Drokin 17271da177e4SLinus Torvalds /* Negative dentry, just create the file */ 17284e7506e4SAl Viro if (!path.dentry->d_inode) { 17294a3fd211SDave Hansen /* 17304a3fd211SDave Hansen * This write is needed to ensure that a 17314a3fd211SDave Hansen * ro->rw transition does not occur between 17324a3fd211SDave Hansen * the time when the file is created and when 17334a3fd211SDave Hansen * a permanent write count is taken through 17344a3fd211SDave Hansen * the 'struct file' in nameidata_to_filp(). 17354a3fd211SDave Hansen */ 17364a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17371da177e4SLinus Torvalds if (error) 17384a3fd211SDave Hansen goto exit_mutex_unlock; 17398737c930SAl Viro error = __open_namei_create(&nd, &path, open_flag, mode); 17404a3fd211SDave Hansen if (error) { 17414a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 17421da177e4SLinus Torvalds goto exit; 17434a3fd211SDave Hansen } 1744482928d5SAl Viro filp = nameidata_to_filp(&nd); 17454a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 1746654f562cSJ. R. Okajima if (nd.root.mnt) 1747654f562cSJ. R. Okajima path_put(&nd.root); 1748b65a9cfcSAl Viro if (!IS_ERR(filp)) { 17499bbb6cadSMimi Zohar error = ima_file_check(filp, acc_mode); 1750b65a9cfcSAl Viro if (error) { 1751b65a9cfcSAl Viro fput(filp); 1752b65a9cfcSAl Viro filp = ERR_PTR(error); 1753b65a9cfcSAl Viro } 1754b65a9cfcSAl Viro } 17554a3fd211SDave Hansen return filp; 17561da177e4SLinus Torvalds } 17571da177e4SLinus Torvalds 17581da177e4SLinus Torvalds /* 17591da177e4SLinus Torvalds * It already exists. 17601da177e4SLinus Torvalds */ 17611b1dcc1bSJes Sorensen mutex_unlock(&dir->d_inode->i_mutex); 17625a190ae6SAl Viro audit_inode(pathname, path.dentry); 17631da177e4SLinus Torvalds 17641da177e4SLinus Torvalds error = -EEXIST; 17651da177e4SLinus Torvalds if (flag & O_EXCL) 17661da177e4SLinus Torvalds goto exit_dput; 17671da177e4SLinus Torvalds 1768e13b210fSAl Viro if (__follow_mount(&path)) { 17691da177e4SLinus Torvalds error = -ELOOP; 1770ba7a4c1aSAl Viro if (flag & O_NOFOLLOW) 1771ba7a4c1aSAl Viro goto exit_dput; 17721da177e4SLinus Torvalds } 17733e2efce0SAmy Griffis 17741da177e4SLinus Torvalds error = -ENOENT; 17754e7506e4SAl Viro if (!path.dentry->d_inode) 17761da177e4SLinus Torvalds goto exit_dput; 1777acfa4380SAl Viro if (path.dentry->d_inode->i_op->follow_link) 17781da177e4SLinus Torvalds goto do_link; 17791da177e4SLinus Torvalds 1780a70e65dfSChristoph Hellwig path_to_nameidata(&path, &nd); 17811da177e4SLinus Torvalds error = -EISDIR; 1782cb59861fSJeff Layton if (S_ISDIR(path.dentry->d_inode->i_mode)) 17831da177e4SLinus Torvalds goto exit; 17841da177e4SLinus Torvalds ok: 17854a3fd211SDave Hansen /* 17864a3fd211SDave Hansen * Consider: 17874a3fd211SDave Hansen * 1. may_open() truncates a file 17884a3fd211SDave Hansen * 2. a rw->ro mount transition occurs 17894a3fd211SDave Hansen * 3. nameidata_to_filp() fails due to 17904a3fd211SDave Hansen * the ro mount. 17914a3fd211SDave Hansen * That would be inconsistent, and should 17924a3fd211SDave Hansen * be avoided. Taking this mnt write here 17934a3fd211SDave Hansen * ensures that (2) can not occur. 17944a3fd211SDave Hansen */ 17957715b521SAl Viro will_truncate = open_will_truncate(flag, nd.path.dentry->d_inode); 17967715b521SAl Viro if (will_truncate) { 17974a3fd211SDave Hansen error = mnt_want_write(nd.path.mnt); 17981da177e4SLinus Torvalds if (error) 17991da177e4SLinus Torvalds goto exit; 18004a3fd211SDave Hansen } 18018737c930SAl Viro error = may_open(&nd.path, acc_mode, open_flag); 18024a3fd211SDave Hansen if (error) { 18037715b521SAl Viro if (will_truncate) 18044a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 18054a3fd211SDave Hansen goto exit; 18064a3fd211SDave Hansen } 1807482928d5SAl Viro filp = nameidata_to_filp(&nd); 1808b65a9cfcSAl Viro if (!IS_ERR(filp)) { 18099bbb6cadSMimi Zohar error = ima_file_check(filp, acc_mode); 1810b65a9cfcSAl Viro if (error) { 1811b65a9cfcSAl Viro fput(filp); 1812b65a9cfcSAl Viro filp = ERR_PTR(error); 18137715b521SAl Viro } 1814b65a9cfcSAl Viro } 1815b65a9cfcSAl Viro if (!IS_ERR(filp)) { 18167715b521SAl Viro if (acc_mode & MAY_WRITE) 18177715b521SAl Viro vfs_dq_init(nd.path.dentry->d_inode); 18187715b521SAl Viro 18197715b521SAl Viro if (will_truncate) { 18207715b521SAl Viro error = handle_truncate(&nd.path); 18217715b521SAl Viro if (error) { 18227715b521SAl Viro fput(filp); 1823b65a9cfcSAl Viro filp = ERR_PTR(error); 1824b65a9cfcSAl Viro } 18257715b521SAl Viro } 18267715b521SAl Viro } 18274a3fd211SDave Hansen /* 18284a3fd211SDave Hansen * It is now safe to drop the mnt write 18294a3fd211SDave Hansen * because the filp has had a write taken 18304a3fd211SDave Hansen * on its behalf. 18314a3fd211SDave Hansen */ 18327715b521SAl Viro if (will_truncate) 18334a3fd211SDave Hansen mnt_drop_write(nd.path.mnt); 1834654f562cSJ. R. Okajima if (nd.root.mnt) 1835654f562cSJ. R. Okajima path_put(&nd.root); 18364a3fd211SDave Hansen return filp; 18371da177e4SLinus Torvalds 18384a3fd211SDave Hansen exit_mutex_unlock: 18394a3fd211SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 18401da177e4SLinus Torvalds exit_dput: 1841a70e65dfSChristoph Hellwig path_put_conditional(&path, &nd); 18421da177e4SLinus Torvalds exit: 1843a70e65dfSChristoph Hellwig if (!IS_ERR(nd.intent.open.file)) 1844a70e65dfSChristoph Hellwig release_open_intent(&nd); 18458737f3a1SAl Viro exit_parent: 18462a737871SAl Viro if (nd.root.mnt) 18472a737871SAl Viro path_put(&nd.root); 1848a70e65dfSChristoph Hellwig path_put(&nd.path); 1849a70e65dfSChristoph Hellwig return ERR_PTR(error); 18501da177e4SLinus Torvalds 18511da177e4SLinus Torvalds do_link: 18521da177e4SLinus Torvalds error = -ELOOP; 18531da177e4SLinus Torvalds if (flag & O_NOFOLLOW) 18541da177e4SLinus Torvalds goto exit_dput; 18551da177e4SLinus Torvalds /* 18561da177e4SLinus Torvalds * This is subtle. Instead of calling do_follow_link() we do the 18571da177e4SLinus Torvalds * thing by hands. The reason is that this way we have zero link_count 18581da177e4SLinus Torvalds * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT. 18591da177e4SLinus Torvalds * After that we have the parent and last component, i.e. 18601da177e4SLinus Torvalds * we are in the same situation as after the first path_walk(). 18611da177e4SLinus Torvalds * Well, almost - if the last component is normal we get its copy 18621da177e4SLinus Torvalds * stored in nd->last.name and we will have to putname() it when we 18631da177e4SLinus Torvalds * are done. Procfs-like symlinks just set LAST_BIND. 18641da177e4SLinus Torvalds */ 1865a70e65dfSChristoph Hellwig nd.flags |= LOOKUP_PARENT; 1866a70e65dfSChristoph Hellwig error = security_inode_follow_link(path.dentry, &nd); 18671da177e4SLinus Torvalds if (error) 18681da177e4SLinus Torvalds goto exit_dput; 1869a70e65dfSChristoph Hellwig error = __do_follow_link(&path, &nd); 1870258fa999SAl Viro path_put(&path); 1871de459215SKirill Korotaev if (error) { 1872de459215SKirill Korotaev /* Does someone understand code flow here? Or it is only 1873de459215SKirill Korotaev * me so stupid? Anathema to whoever designed this non-sense 1874de459215SKirill Korotaev * with "intent.open". 1875de459215SKirill Korotaev */ 1876a70e65dfSChristoph Hellwig release_open_intent(&nd); 1877654f562cSJ. R. Okajima if (nd.root.mnt) 1878654f562cSJ. R. Okajima path_put(&nd.root); 18799850c056SAl Viro if (error == -ESTALE && !force_reval) { 18809850c056SAl Viro force_reval = 1; 18819850c056SAl Viro goto reval; 18829850c056SAl Viro } 1883a70e65dfSChristoph Hellwig return ERR_PTR(error); 1884de459215SKirill Korotaev } 1885a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 1886a70e65dfSChristoph Hellwig if (nd.last_type == LAST_BIND) 18871da177e4SLinus Torvalds goto ok; 18881da177e4SLinus Torvalds error = -EISDIR; 1889a70e65dfSChristoph Hellwig if (nd.last_type != LAST_NORM) 18901da177e4SLinus Torvalds goto exit; 1891a70e65dfSChristoph Hellwig if (nd.last.name[nd.last.len]) { 1892a70e65dfSChristoph Hellwig __putname(nd.last.name); 18931da177e4SLinus Torvalds goto exit; 18941da177e4SLinus Torvalds } 18951da177e4SLinus Torvalds error = -ELOOP; 18961da177e4SLinus Torvalds if (count++==32) { 1897a70e65dfSChristoph Hellwig __putname(nd.last.name); 18981da177e4SLinus Torvalds goto exit; 18991da177e4SLinus Torvalds } 1900a70e65dfSChristoph Hellwig dir = nd.path.dentry; 19011b1dcc1bSJes Sorensen mutex_lock(&dir->d_inode->i_mutex); 1902a70e65dfSChristoph Hellwig path.dentry = lookup_hash(&nd); 1903a70e65dfSChristoph Hellwig path.mnt = nd.path.mnt; 1904a70e65dfSChristoph Hellwig __putname(nd.last.name); 19051da177e4SLinus Torvalds goto do_last; 19061da177e4SLinus Torvalds } 19071da177e4SLinus Torvalds 19081da177e4SLinus Torvalds /** 1909a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1910a70e65dfSChristoph Hellwig * 1911a70e65dfSChristoph Hellwig * @filename: path to open 1912a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1913a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1914a70e65dfSChristoph Hellwig * 1915a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1916a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1917a70e65dfSChristoph Hellwig * along, nothing to see here.. 1918a70e65dfSChristoph Hellwig */ 1919a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1920a70e65dfSChristoph Hellwig { 19216e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 1922a70e65dfSChristoph Hellwig } 1923a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1924a70e65dfSChristoph Hellwig 1925a70e65dfSChristoph Hellwig /** 19261da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 19271da177e4SLinus Torvalds * @nd: nameidata info 19281da177e4SLinus Torvalds * @is_dir: directory flag 19291da177e4SLinus Torvalds * 19301da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 19311da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1932c663e5d8SChristoph Hellwig * 19334ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 19341da177e4SLinus Torvalds */ 19351da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 19361da177e4SLinus Torvalds { 1937c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 19381da177e4SLinus Torvalds 19394ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1940c663e5d8SChristoph Hellwig /* 1941c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1942c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1943c663e5d8SChristoph Hellwig */ 19441da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19451da177e4SLinus Torvalds goto fail; 19461da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 19473516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1948a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1949c663e5d8SChristoph Hellwig 1950c663e5d8SChristoph Hellwig /* 1951c663e5d8SChristoph Hellwig * Do the final lookup. 1952c663e5d8SChristoph Hellwig */ 195349705b77SChristoph Hellwig dentry = lookup_hash(nd); 19541da177e4SLinus Torvalds if (IS_ERR(dentry)) 19551da177e4SLinus Torvalds goto fail; 1956c663e5d8SChristoph Hellwig 1957e9baf6e5SAl Viro if (dentry->d_inode) 1958e9baf6e5SAl Viro goto eexist; 1959c663e5d8SChristoph Hellwig /* 1960c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1961c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1962c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1963c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1964c663e5d8SChristoph Hellwig */ 1965e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19661da177e4SLinus Torvalds dput(dentry); 19671da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1968e9baf6e5SAl Viro } 1969e9baf6e5SAl Viro return dentry; 1970e9baf6e5SAl Viro eexist: 1971e9baf6e5SAl Viro dput(dentry); 1972e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19731da177e4SLinus Torvalds fail: 19741da177e4SLinus Torvalds return dentry; 19751da177e4SLinus Torvalds } 1976f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19771da177e4SLinus Torvalds 19781da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19791da177e4SLinus Torvalds { 1980a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19811da177e4SLinus Torvalds 19821da177e4SLinus Torvalds if (error) 19831da177e4SLinus Torvalds return error; 19841da177e4SLinus Torvalds 19851da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19861da177e4SLinus Torvalds return -EPERM; 19871da177e4SLinus Torvalds 1988acfa4380SAl Viro if (!dir->i_op->mknod) 19891da177e4SLinus Torvalds return -EPERM; 19901da177e4SLinus Torvalds 199108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 199208ce5f16SSerge E. Hallyn if (error) 199308ce5f16SSerge E. Hallyn return error; 199408ce5f16SSerge E. Hallyn 19951da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19961da177e4SLinus Torvalds if (error) 19971da177e4SLinus Torvalds return error; 19981da177e4SLinus Torvalds 19999e3509e2SJan Kara vfs_dq_init(dir); 20001da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2001a74574aaSStephen Smalley if (!error) 2002f38aa942SAmy Griffis fsnotify_create(dir, dentry); 20031da177e4SLinus Torvalds return error; 20041da177e4SLinus Torvalds } 20051da177e4SLinus Torvalds 2006463c3197SDave Hansen static int may_mknod(mode_t mode) 2007463c3197SDave Hansen { 2008463c3197SDave Hansen switch (mode & S_IFMT) { 2009463c3197SDave Hansen case S_IFREG: 2010463c3197SDave Hansen case S_IFCHR: 2011463c3197SDave Hansen case S_IFBLK: 2012463c3197SDave Hansen case S_IFIFO: 2013463c3197SDave Hansen case S_IFSOCK: 2014463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2015463c3197SDave Hansen return 0; 2016463c3197SDave Hansen case S_IFDIR: 2017463c3197SDave Hansen return -EPERM; 2018463c3197SDave Hansen default: 2019463c3197SDave Hansen return -EINVAL; 2020463c3197SDave Hansen } 2021463c3197SDave Hansen } 2022463c3197SDave Hansen 20232e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 20242e4d0924SHeiko Carstens unsigned, dev) 20251da177e4SLinus Torvalds { 20262ad94ae6SAl Viro int error; 20271da177e4SLinus Torvalds char *tmp; 20281da177e4SLinus Torvalds struct dentry *dentry; 20291da177e4SLinus Torvalds struct nameidata nd; 20301da177e4SLinus Torvalds 20311da177e4SLinus Torvalds if (S_ISDIR(mode)) 20321da177e4SLinus Torvalds return -EPERM; 20331da177e4SLinus Torvalds 20342ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 20351da177e4SLinus Torvalds if (error) 20362ad94ae6SAl Viro return error; 20372ad94ae6SAl Viro 20381da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2039463c3197SDave Hansen if (IS_ERR(dentry)) { 20401da177e4SLinus Torvalds error = PTR_ERR(dentry); 2041463c3197SDave Hansen goto out_unlock; 2042463c3197SDave Hansen } 20434ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2044ce3b0f8dSAl Viro mode &= ~current_umask(); 2045463c3197SDave Hansen error = may_mknod(mode); 2046463c3197SDave Hansen if (error) 2047463c3197SDave Hansen goto out_dput; 2048463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2049463c3197SDave Hansen if (error) 2050463c3197SDave Hansen goto out_dput; 2051be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2052be6d3e56SKentaro Takeda if (error) 2053be6d3e56SKentaro Takeda goto out_drop_write; 20541da177e4SLinus Torvalds switch (mode & S_IFMT) { 20551da177e4SLinus Torvalds case 0: case S_IFREG: 20564ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20571da177e4SLinus Torvalds break; 20581da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20594ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20601da177e4SLinus Torvalds new_decode_dev(dev)); 20611da177e4SLinus Torvalds break; 20621da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20634ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20641da177e4SLinus Torvalds break; 20651da177e4SLinus Torvalds } 2066be6d3e56SKentaro Takeda out_drop_write: 2067463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2068463c3197SDave Hansen out_dput: 20691da177e4SLinus Torvalds dput(dentry); 2070463c3197SDave Hansen out_unlock: 20714ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20721d957f9bSJan Blunck path_put(&nd.path); 20731da177e4SLinus Torvalds putname(tmp); 20741da177e4SLinus Torvalds 20751da177e4SLinus Torvalds return error; 20761da177e4SLinus Torvalds } 20771da177e4SLinus Torvalds 20783480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 20795590ff0dSUlrich Drepper { 20805590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20815590ff0dSUlrich Drepper } 20825590ff0dSUlrich Drepper 20831da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20841da177e4SLinus Torvalds { 2085a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20861da177e4SLinus Torvalds 20871da177e4SLinus Torvalds if (error) 20881da177e4SLinus Torvalds return error; 20891da177e4SLinus Torvalds 2090acfa4380SAl Viro if (!dir->i_op->mkdir) 20911da177e4SLinus Torvalds return -EPERM; 20921da177e4SLinus Torvalds 20931da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20941da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20951da177e4SLinus Torvalds if (error) 20961da177e4SLinus Torvalds return error; 20971da177e4SLinus Torvalds 20989e3509e2SJan Kara vfs_dq_init(dir); 20991da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2100a74574aaSStephen Smalley if (!error) 2101f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 21021da177e4SLinus Torvalds return error; 21031da177e4SLinus Torvalds } 21041da177e4SLinus Torvalds 21052e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 21061da177e4SLinus Torvalds { 21071da177e4SLinus Torvalds int error = 0; 21081da177e4SLinus Torvalds char * tmp; 21096902d925SDave Hansen struct dentry *dentry; 21106902d925SDave Hansen struct nameidata nd; 21111da177e4SLinus Torvalds 21122ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 21132ad94ae6SAl Viro if (error) 21146902d925SDave Hansen goto out_err; 21151da177e4SLinus Torvalds 21161da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 21171da177e4SLinus Torvalds error = PTR_ERR(dentry); 21186902d925SDave Hansen if (IS_ERR(dentry)) 21196902d925SDave Hansen goto out_unlock; 21206902d925SDave Hansen 21214ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2122ce3b0f8dSAl Viro mode &= ~current_umask(); 2123463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2124463c3197SDave Hansen if (error) 2125463c3197SDave Hansen goto out_dput; 2126be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2127be6d3e56SKentaro Takeda if (error) 2128be6d3e56SKentaro Takeda goto out_drop_write; 21294ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2130be6d3e56SKentaro Takeda out_drop_write: 2131463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2132463c3197SDave Hansen out_dput: 21331da177e4SLinus Torvalds dput(dentry); 21346902d925SDave Hansen out_unlock: 21354ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21361d957f9bSJan Blunck path_put(&nd.path); 21371da177e4SLinus Torvalds putname(tmp); 21386902d925SDave Hansen out_err: 21391da177e4SLinus Torvalds return error; 21401da177e4SLinus Torvalds } 21411da177e4SLinus Torvalds 21423cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 21435590ff0dSUlrich Drepper { 21445590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 21455590ff0dSUlrich Drepper } 21465590ff0dSUlrich Drepper 21471da177e4SLinus Torvalds /* 21481da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21491da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21501da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 21511da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21521da177e4SLinus Torvalds * 21531da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21541da177e4SLinus Torvalds * do a 21551da177e4SLinus Torvalds * 21561da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21571da177e4SLinus Torvalds * return -EBUSY; 21581da177e4SLinus Torvalds * 21591da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21601da177e4SLinus Torvalds * that is still in use by something else.. 21611da177e4SLinus Torvalds */ 21621da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21631da177e4SLinus Torvalds { 21641da177e4SLinus Torvalds dget(dentry); 21651da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21661da177e4SLinus Torvalds spin_lock(&dcache_lock); 21671da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21681da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21691da177e4SLinus Torvalds __d_drop(dentry); 21701da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21711da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21721da177e4SLinus Torvalds } 21731da177e4SLinus Torvalds 21741da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21751da177e4SLinus Torvalds { 21761da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21771da177e4SLinus Torvalds 21781da177e4SLinus Torvalds if (error) 21791da177e4SLinus Torvalds return error; 21801da177e4SLinus Torvalds 2181acfa4380SAl Viro if (!dir->i_op->rmdir) 21821da177e4SLinus Torvalds return -EPERM; 21831da177e4SLinus Torvalds 21849e3509e2SJan Kara vfs_dq_init(dir); 21851da177e4SLinus Torvalds 21861b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21871da177e4SLinus Torvalds dentry_unhash(dentry); 21881da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21891da177e4SLinus Torvalds error = -EBUSY; 21901da177e4SLinus Torvalds else { 21911da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21921da177e4SLinus Torvalds if (!error) { 21931da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 21941da177e4SLinus Torvalds if (!error) 21951da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 21961da177e4SLinus Torvalds } 21971da177e4SLinus Torvalds } 21981b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21991da177e4SLinus Torvalds if (!error) { 22001da177e4SLinus Torvalds d_delete(dentry); 22011da177e4SLinus Torvalds } 22021da177e4SLinus Torvalds dput(dentry); 22031da177e4SLinus Torvalds 22041da177e4SLinus Torvalds return error; 22051da177e4SLinus Torvalds } 22061da177e4SLinus Torvalds 22075590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 22081da177e4SLinus Torvalds { 22091da177e4SLinus Torvalds int error = 0; 22101da177e4SLinus Torvalds char * name; 22111da177e4SLinus Torvalds struct dentry *dentry; 22121da177e4SLinus Torvalds struct nameidata nd; 22131da177e4SLinus Torvalds 22142ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22151da177e4SLinus Torvalds if (error) 22162ad94ae6SAl Viro return error; 22171da177e4SLinus Torvalds 22181da177e4SLinus Torvalds switch(nd.last_type) { 22191da177e4SLinus Torvalds case LAST_DOTDOT: 22201da177e4SLinus Torvalds error = -ENOTEMPTY; 22211da177e4SLinus Torvalds goto exit1; 22221da177e4SLinus Torvalds case LAST_DOT: 22231da177e4SLinus Torvalds error = -EINVAL; 22241da177e4SLinus Torvalds goto exit1; 22251da177e4SLinus Torvalds case LAST_ROOT: 22261da177e4SLinus Torvalds error = -EBUSY; 22271da177e4SLinus Torvalds goto exit1; 22281da177e4SLinus Torvalds } 22290612d9fbSOGAWA Hirofumi 22300612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22310612d9fbSOGAWA Hirofumi 22324ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 223349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22341da177e4SLinus Torvalds error = PTR_ERR(dentry); 22356902d925SDave Hansen if (IS_ERR(dentry)) 22366902d925SDave Hansen goto exit2; 22370622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22380622753bSDave Hansen if (error) 22390622753bSDave Hansen goto exit3; 2240be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2241be6d3e56SKentaro Takeda if (error) 2242be6d3e56SKentaro Takeda goto exit4; 22434ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2244be6d3e56SKentaro Takeda exit4: 22450622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22460622753bSDave Hansen exit3: 22471da177e4SLinus Torvalds dput(dentry); 22486902d925SDave Hansen exit2: 22494ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22501da177e4SLinus Torvalds exit1: 22511d957f9bSJan Blunck path_put(&nd.path); 22521da177e4SLinus Torvalds putname(name); 22531da177e4SLinus Torvalds return error; 22541da177e4SLinus Torvalds } 22551da177e4SLinus Torvalds 22563cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 22575590ff0dSUlrich Drepper { 22585590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22595590ff0dSUlrich Drepper } 22605590ff0dSUlrich Drepper 22611da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22621da177e4SLinus Torvalds { 22631da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22641da177e4SLinus Torvalds 22651da177e4SLinus Torvalds if (error) 22661da177e4SLinus Torvalds return error; 22671da177e4SLinus Torvalds 2268acfa4380SAl Viro if (!dir->i_op->unlink) 22691da177e4SLinus Torvalds return -EPERM; 22701da177e4SLinus Torvalds 22719e3509e2SJan Kara vfs_dq_init(dir); 22721da177e4SLinus Torvalds 22731b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22741da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22751da177e4SLinus Torvalds error = -EBUSY; 22761da177e4SLinus Torvalds else { 22771da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 22781da177e4SLinus Torvalds if (!error) 22791da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 22801da177e4SLinus Torvalds } 22811b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22821da177e4SLinus Torvalds 22831da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22841da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2285ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22861da177e4SLinus Torvalds d_delete(dentry); 22871da177e4SLinus Torvalds } 22880eeca283SRobert Love 22891da177e4SLinus Torvalds return error; 22901da177e4SLinus Torvalds } 22911da177e4SLinus Torvalds 22921da177e4SLinus Torvalds /* 22931da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22941b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22951da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22961da177e4SLinus Torvalds * while waiting on the I/O. 22971da177e4SLinus Torvalds */ 22985590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22991da177e4SLinus Torvalds { 23002ad94ae6SAl Viro int error; 23011da177e4SLinus Torvalds char *name; 23021da177e4SLinus Torvalds struct dentry *dentry; 23031da177e4SLinus Torvalds struct nameidata nd; 23041da177e4SLinus Torvalds struct inode *inode = NULL; 23051da177e4SLinus Torvalds 23062ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 23071da177e4SLinus Torvalds if (error) 23082ad94ae6SAl Viro return error; 23092ad94ae6SAl Viro 23101da177e4SLinus Torvalds error = -EISDIR; 23111da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 23121da177e4SLinus Torvalds goto exit1; 23130612d9fbSOGAWA Hirofumi 23140612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 23150612d9fbSOGAWA Hirofumi 23164ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 231749705b77SChristoph Hellwig dentry = lookup_hash(&nd); 23181da177e4SLinus Torvalds error = PTR_ERR(dentry); 23191da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 23201da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 23211da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 23221da177e4SLinus Torvalds goto slashes; 23231da177e4SLinus Torvalds inode = dentry->d_inode; 23241da177e4SLinus Torvalds if (inode) 23251da177e4SLinus Torvalds atomic_inc(&inode->i_count); 23260622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23270622753bSDave Hansen if (error) 23280622753bSDave Hansen goto exit2; 2329be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2330be6d3e56SKentaro Takeda if (error) 2331be6d3e56SKentaro Takeda goto exit3; 23324ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2333be6d3e56SKentaro Takeda exit3: 23340622753bSDave Hansen mnt_drop_write(nd.path.mnt); 23351da177e4SLinus Torvalds exit2: 23361da177e4SLinus Torvalds dput(dentry); 23371da177e4SLinus Torvalds } 23384ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23391da177e4SLinus Torvalds if (inode) 23401da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 23411da177e4SLinus Torvalds exit1: 23421d957f9bSJan Blunck path_put(&nd.path); 23431da177e4SLinus Torvalds putname(name); 23441da177e4SLinus Torvalds return error; 23451da177e4SLinus Torvalds 23461da177e4SLinus Torvalds slashes: 23471da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 23481da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 23491da177e4SLinus Torvalds goto exit2; 23501da177e4SLinus Torvalds } 23511da177e4SLinus Torvalds 23522e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 23535590ff0dSUlrich Drepper { 23545590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23555590ff0dSUlrich Drepper return -EINVAL; 23565590ff0dSUlrich Drepper 23575590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23585590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23595590ff0dSUlrich Drepper 23605590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23615590ff0dSUlrich Drepper } 23625590ff0dSUlrich Drepper 23633480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 23645590ff0dSUlrich Drepper { 23655590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23665590ff0dSUlrich Drepper } 23675590ff0dSUlrich Drepper 2368db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23691da177e4SLinus Torvalds { 2370a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23711da177e4SLinus Torvalds 23721da177e4SLinus Torvalds if (error) 23731da177e4SLinus Torvalds return error; 23741da177e4SLinus Torvalds 2375acfa4380SAl Viro if (!dir->i_op->symlink) 23761da177e4SLinus Torvalds return -EPERM; 23771da177e4SLinus Torvalds 23781da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23791da177e4SLinus Torvalds if (error) 23801da177e4SLinus Torvalds return error; 23811da177e4SLinus Torvalds 23829e3509e2SJan Kara vfs_dq_init(dir); 23831da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2384a74574aaSStephen Smalley if (!error) 2385f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23861da177e4SLinus Torvalds return error; 23871da177e4SLinus Torvalds } 23881da177e4SLinus Torvalds 23892e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 23902e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 23911da177e4SLinus Torvalds { 23922ad94ae6SAl Viro int error; 23931da177e4SLinus Torvalds char *from; 23941da177e4SLinus Torvalds char *to; 23956902d925SDave Hansen struct dentry *dentry; 23966902d925SDave Hansen struct nameidata nd; 23971da177e4SLinus Torvalds 23981da177e4SLinus Torvalds from = getname(oldname); 23991da177e4SLinus Torvalds if (IS_ERR(from)) 24001da177e4SLinus Torvalds return PTR_ERR(from); 24012ad94ae6SAl Viro 24022ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24032ad94ae6SAl Viro if (error) 24046902d925SDave Hansen goto out_putname; 24051da177e4SLinus Torvalds 24061da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 24071da177e4SLinus Torvalds error = PTR_ERR(dentry); 24086902d925SDave Hansen if (IS_ERR(dentry)) 24096902d925SDave Hansen goto out_unlock; 24106902d925SDave Hansen 241175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 241275c3f29dSDave Hansen if (error) 241375c3f29dSDave Hansen goto out_dput; 2414be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2415be6d3e56SKentaro Takeda if (error) 2416be6d3e56SKentaro Takeda goto out_drop_write; 2417db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2418be6d3e56SKentaro Takeda out_drop_write: 241975c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 242075c3f29dSDave Hansen out_dput: 24211da177e4SLinus Torvalds dput(dentry); 24226902d925SDave Hansen out_unlock: 24234ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24241d957f9bSJan Blunck path_put(&nd.path); 24251da177e4SLinus Torvalds putname(to); 24266902d925SDave Hansen out_putname: 24271da177e4SLinus Torvalds putname(from); 24281da177e4SLinus Torvalds return error; 24291da177e4SLinus Torvalds } 24301da177e4SLinus Torvalds 24313480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 24325590ff0dSUlrich Drepper { 24335590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 24345590ff0dSUlrich Drepper } 24355590ff0dSUlrich Drepper 24361da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 24371da177e4SLinus Torvalds { 24381da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 24391da177e4SLinus Torvalds int error; 24401da177e4SLinus Torvalds 24411da177e4SLinus Torvalds if (!inode) 24421da177e4SLinus Torvalds return -ENOENT; 24431da177e4SLinus Torvalds 2444a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 24451da177e4SLinus Torvalds if (error) 24461da177e4SLinus Torvalds return error; 24471da177e4SLinus Torvalds 24481da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 24491da177e4SLinus Torvalds return -EXDEV; 24501da177e4SLinus Torvalds 24511da177e4SLinus Torvalds /* 24521da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24531da177e4SLinus Torvalds */ 24541da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24551da177e4SLinus Torvalds return -EPERM; 2456acfa4380SAl Viro if (!dir->i_op->link) 24571da177e4SLinus Torvalds return -EPERM; 24587e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24591da177e4SLinus Torvalds return -EPERM; 24601da177e4SLinus Torvalds 24611da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24621da177e4SLinus Torvalds if (error) 24631da177e4SLinus Torvalds return error; 24641da177e4SLinus Torvalds 24657e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24669e3509e2SJan Kara vfs_dq_init(dir); 24671da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24687e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2469e31e14ecSStephen Smalley if (!error) 24707e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24711da177e4SLinus Torvalds return error; 24721da177e4SLinus Torvalds } 24731da177e4SLinus Torvalds 24741da177e4SLinus Torvalds /* 24751da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24761da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24771da177e4SLinus Torvalds * newname. --KAB 24781da177e4SLinus Torvalds * 24791da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24801da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24811da177e4SLinus Torvalds * and other special files. --ADM 24821da177e4SLinus Torvalds */ 24832e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 24842e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 24851da177e4SLinus Torvalds { 24861da177e4SLinus Torvalds struct dentry *new_dentry; 24872d8f3038SAl Viro struct nameidata nd; 24882d8f3038SAl Viro struct path old_path; 24891da177e4SLinus Torvalds int error; 24901da177e4SLinus Torvalds char *to; 24911da177e4SLinus Torvalds 249245c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2493c04030e1SUlrich Drepper return -EINVAL; 2494c04030e1SUlrich Drepper 24952d8f3038SAl Viro error = user_path_at(olddfd, oldname, 249645c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24972d8f3038SAl Viro &old_path); 24981da177e4SLinus Torvalds if (error) 24992ad94ae6SAl Viro return error; 25002ad94ae6SAl Viro 25012ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 25021da177e4SLinus Torvalds if (error) 25031da177e4SLinus Torvalds goto out; 25041da177e4SLinus Torvalds error = -EXDEV; 25052d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 25061da177e4SLinus Torvalds goto out_release; 25071da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 25081da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 25096902d925SDave Hansen if (IS_ERR(new_dentry)) 25106902d925SDave Hansen goto out_unlock; 251175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 251275c3f29dSDave Hansen if (error) 251375c3f29dSDave Hansen goto out_dput; 2514be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2515be6d3e56SKentaro Takeda if (error) 2516be6d3e56SKentaro Takeda goto out_drop_write; 25172d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2518be6d3e56SKentaro Takeda out_drop_write: 251975c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 252075c3f29dSDave Hansen out_dput: 25211da177e4SLinus Torvalds dput(new_dentry); 25226902d925SDave Hansen out_unlock: 25234ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25241da177e4SLinus Torvalds out_release: 25251d957f9bSJan Blunck path_put(&nd.path); 25262ad94ae6SAl Viro putname(to); 25271da177e4SLinus Torvalds out: 25282d8f3038SAl Viro path_put(&old_path); 25291da177e4SLinus Torvalds 25301da177e4SLinus Torvalds return error; 25311da177e4SLinus Torvalds } 25321da177e4SLinus Torvalds 25333480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 25345590ff0dSUlrich Drepper { 2535c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 25365590ff0dSUlrich Drepper } 25375590ff0dSUlrich Drepper 25381da177e4SLinus Torvalds /* 25391da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 25401da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 25411da177e4SLinus Torvalds * Problems: 25421da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 25431da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 25441da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2545a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 25461da177e4SLinus Torvalds * story. 25471da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 25481b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 25491da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 25501da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2551a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25521da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25531da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25541da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2555a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 25561da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25571da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25581da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25591da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25601da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25611da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25621da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25631da177e4SLinus Torvalds * trick as in rmdir(). 25641da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25651b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25661da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 25671b1dcc1bSJes Sorensen * ->i_mutex on parents, which works but leads to some truely excessive 25681da177e4SLinus Torvalds * locking]. 25691da177e4SLinus Torvalds */ 257075c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25711da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25721da177e4SLinus Torvalds { 25731da177e4SLinus Torvalds int error = 0; 25741da177e4SLinus Torvalds struct inode *target; 25751da177e4SLinus Torvalds 25761da177e4SLinus Torvalds /* 25771da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25781da177e4SLinus Torvalds * we'll need to flip '..'. 25791da177e4SLinus Torvalds */ 25801da177e4SLinus Torvalds if (new_dir != old_dir) { 2581f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25821da177e4SLinus Torvalds if (error) 25831da177e4SLinus Torvalds return error; 25841da177e4SLinus Torvalds } 25851da177e4SLinus Torvalds 25861da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25871da177e4SLinus Torvalds if (error) 25881da177e4SLinus Torvalds return error; 25891da177e4SLinus Torvalds 25901da177e4SLinus Torvalds target = new_dentry->d_inode; 25911da177e4SLinus Torvalds if (target) { 25921b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25931da177e4SLinus Torvalds dentry_unhash(new_dentry); 25941da177e4SLinus Torvalds } 25951da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25961da177e4SLinus Torvalds error = -EBUSY; 25971da177e4SLinus Torvalds else 25981da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 25991da177e4SLinus Torvalds if (target) { 26001da177e4SLinus Torvalds if (!error) 26011da177e4SLinus Torvalds target->i_flags |= S_DEAD; 26021b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26031da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 26041da177e4SLinus Torvalds d_rehash(new_dentry); 26051da177e4SLinus Torvalds dput(new_dentry); 26061da177e4SLinus Torvalds } 2607e31e14ecSStephen Smalley if (!error) 2608349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26091da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 26101da177e4SLinus Torvalds return error; 26111da177e4SLinus Torvalds } 26121da177e4SLinus Torvalds 261375c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 26141da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26151da177e4SLinus Torvalds { 26161da177e4SLinus Torvalds struct inode *target; 26171da177e4SLinus Torvalds int error; 26181da177e4SLinus Torvalds 26191da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26201da177e4SLinus Torvalds if (error) 26211da177e4SLinus Torvalds return error; 26221da177e4SLinus Torvalds 26231da177e4SLinus Torvalds dget(new_dentry); 26241da177e4SLinus Torvalds target = new_dentry->d_inode; 26251da177e4SLinus Torvalds if (target) 26261b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26271da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26281da177e4SLinus Torvalds error = -EBUSY; 26291da177e4SLinus Torvalds else 26301da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26311da177e4SLinus Torvalds if (!error) { 2632349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26331da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 26341da177e4SLinus Torvalds } 26351da177e4SLinus Torvalds if (target) 26361b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26371da177e4SLinus Torvalds dput(new_dentry); 26381da177e4SLinus Torvalds return error; 26391da177e4SLinus Torvalds } 26401da177e4SLinus Torvalds 26411da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 26421da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26431da177e4SLinus Torvalds { 26441da177e4SLinus Torvalds int error; 26451da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 26460eeca283SRobert Love const char *old_name; 26471da177e4SLinus Torvalds 26481da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 26491da177e4SLinus Torvalds return 0; 26501da177e4SLinus Torvalds 26511da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26521da177e4SLinus Torvalds if (error) 26531da177e4SLinus Torvalds return error; 26541da177e4SLinus Torvalds 26551da177e4SLinus Torvalds if (!new_dentry->d_inode) 2656a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 26571da177e4SLinus Torvalds else 26581da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26591da177e4SLinus Torvalds if (error) 26601da177e4SLinus Torvalds return error; 26611da177e4SLinus Torvalds 2662acfa4380SAl Viro if (!old_dir->i_op->rename) 26631da177e4SLinus Torvalds return -EPERM; 26641da177e4SLinus Torvalds 26659e3509e2SJan Kara vfs_dq_init(old_dir); 26669e3509e2SJan Kara vfs_dq_init(new_dir); 26671da177e4SLinus Torvalds 26680eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26690eeca283SRobert Love 26701da177e4SLinus Torvalds if (is_dir) 26711da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26721da177e4SLinus Torvalds else 26731da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 26741da177e4SLinus Torvalds if (!error) { 26750eeca283SRobert Love const char *new_name = old_dentry->d_name.name; 267689204c40SJohn McCutchan fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir, 26775a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26781da177e4SLinus Torvalds } 26790eeca283SRobert Love fsnotify_oldname_free(old_name); 26800eeca283SRobert Love 26811da177e4SLinus Torvalds return error; 26821da177e4SLinus Torvalds } 26831da177e4SLinus Torvalds 26842e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 26852e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 26861da177e4SLinus Torvalds { 26871da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26881da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26891da177e4SLinus Torvalds struct dentry *trap; 26901da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26912ad94ae6SAl Viro char *from; 26922ad94ae6SAl Viro char *to; 26932ad94ae6SAl Viro int error; 26941da177e4SLinus Torvalds 26952ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26961da177e4SLinus Torvalds if (error) 26971da177e4SLinus Torvalds goto exit; 26981da177e4SLinus Torvalds 26992ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 27001da177e4SLinus Torvalds if (error) 27011da177e4SLinus Torvalds goto exit1; 27021da177e4SLinus Torvalds 27031da177e4SLinus Torvalds error = -EXDEV; 27044ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 27051da177e4SLinus Torvalds goto exit2; 27061da177e4SLinus Torvalds 27074ac91378SJan Blunck old_dir = oldnd.path.dentry; 27081da177e4SLinus Torvalds error = -EBUSY; 27091da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 27101da177e4SLinus Torvalds goto exit2; 27111da177e4SLinus Torvalds 27124ac91378SJan Blunck new_dir = newnd.path.dentry; 27131da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 27141da177e4SLinus Torvalds goto exit2; 27151da177e4SLinus Torvalds 27160612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 27170612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 27184e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 27190612d9fbSOGAWA Hirofumi 27201da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 27211da177e4SLinus Torvalds 272249705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 27231da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 27241da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 27251da177e4SLinus Torvalds goto exit3; 27261da177e4SLinus Torvalds /* source must exist */ 27271da177e4SLinus Torvalds error = -ENOENT; 27281da177e4SLinus Torvalds if (!old_dentry->d_inode) 27291da177e4SLinus Torvalds goto exit4; 27301da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 27311da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 27321da177e4SLinus Torvalds error = -ENOTDIR; 27331da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 27341da177e4SLinus Torvalds goto exit4; 27351da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 27361da177e4SLinus Torvalds goto exit4; 27371da177e4SLinus Torvalds } 27381da177e4SLinus Torvalds /* source should not be ancestor of target */ 27391da177e4SLinus Torvalds error = -EINVAL; 27401da177e4SLinus Torvalds if (old_dentry == trap) 27411da177e4SLinus Torvalds goto exit4; 274249705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 27431da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 27441da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 27451da177e4SLinus Torvalds goto exit4; 27461da177e4SLinus Torvalds /* target should not be an ancestor of source */ 27471da177e4SLinus Torvalds error = -ENOTEMPTY; 27481da177e4SLinus Torvalds if (new_dentry == trap) 27491da177e4SLinus Torvalds goto exit5; 27501da177e4SLinus Torvalds 27519079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27529079b1ebSDave Hansen if (error) 27539079b1ebSDave Hansen goto exit5; 2754be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 2755be6d3e56SKentaro Takeda &newnd.path, new_dentry); 2756be6d3e56SKentaro Takeda if (error) 2757be6d3e56SKentaro Takeda goto exit6; 27581da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27591da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 2760be6d3e56SKentaro Takeda exit6: 27619079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27621da177e4SLinus Torvalds exit5: 27631da177e4SLinus Torvalds dput(new_dentry); 27641da177e4SLinus Torvalds exit4: 27651da177e4SLinus Torvalds dput(old_dentry); 27661da177e4SLinus Torvalds exit3: 27671da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27681da177e4SLinus Torvalds exit2: 27691d957f9bSJan Blunck path_put(&newnd.path); 27702ad94ae6SAl Viro putname(to); 27711da177e4SLinus Torvalds exit1: 27721d957f9bSJan Blunck path_put(&oldnd.path); 27731da177e4SLinus Torvalds putname(from); 27742ad94ae6SAl Viro exit: 27751da177e4SLinus Torvalds return error; 27761da177e4SLinus Torvalds } 27771da177e4SLinus Torvalds 2778a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 27795590ff0dSUlrich Drepper { 27805590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27815590ff0dSUlrich Drepper } 27825590ff0dSUlrich Drepper 27831da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27841da177e4SLinus Torvalds { 27851da177e4SLinus Torvalds int len; 27861da177e4SLinus Torvalds 27871da177e4SLinus Torvalds len = PTR_ERR(link); 27881da177e4SLinus Torvalds if (IS_ERR(link)) 27891da177e4SLinus Torvalds goto out; 27901da177e4SLinus Torvalds 27911da177e4SLinus Torvalds len = strlen(link); 27921da177e4SLinus Torvalds if (len > (unsigned) buflen) 27931da177e4SLinus Torvalds len = buflen; 27941da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27951da177e4SLinus Torvalds len = -EFAULT; 27961da177e4SLinus Torvalds out: 27971da177e4SLinus Torvalds return len; 27981da177e4SLinus Torvalds } 27991da177e4SLinus Torvalds 28001da177e4SLinus Torvalds /* 28011da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 28021da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 28031da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 28041da177e4SLinus Torvalds */ 28051da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28061da177e4SLinus Torvalds { 28071da177e4SLinus Torvalds struct nameidata nd; 2808cc314eefSLinus Torvalds void *cookie; 2809694a1764SMarcin Slusarz int res; 2810cc314eefSLinus Torvalds 28111da177e4SLinus Torvalds nd.depth = 0; 2812cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2813694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2814694a1764SMarcin Slusarz return PTR_ERR(cookie); 2815694a1764SMarcin Slusarz 2816694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 28171da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2818cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2819694a1764SMarcin Slusarz return res; 28201da177e4SLinus Torvalds } 28211da177e4SLinus Torvalds 28221da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 28231da177e4SLinus Torvalds { 28241da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 28251da177e4SLinus Torvalds } 28261da177e4SLinus Torvalds 28271da177e4SLinus Torvalds /* get the link contents into pagecache */ 28281da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 28291da177e4SLinus Torvalds { 2830ebd09abbSDuane Griffin char *kaddr; 28311da177e4SLinus Torvalds struct page *page; 28321da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2833090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 28341da177e4SLinus Torvalds if (IS_ERR(page)) 28356fe6900eSNick Piggin return (char*)page; 28361da177e4SLinus Torvalds *ppage = page; 2837ebd09abbSDuane Griffin kaddr = kmap(page); 2838ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 2839ebd09abbSDuane Griffin return kaddr; 28401da177e4SLinus Torvalds } 28411da177e4SLinus Torvalds 28421da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28431da177e4SLinus Torvalds { 28441da177e4SLinus Torvalds struct page *page = NULL; 28451da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 28461da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 28471da177e4SLinus Torvalds if (page) { 28481da177e4SLinus Torvalds kunmap(page); 28491da177e4SLinus Torvalds page_cache_release(page); 28501da177e4SLinus Torvalds } 28511da177e4SLinus Torvalds return res; 28521da177e4SLinus Torvalds } 28531da177e4SLinus Torvalds 2854cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 28551da177e4SLinus Torvalds { 2856cc314eefSLinus Torvalds struct page *page = NULL; 28571da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2858cc314eefSLinus Torvalds return page; 28591da177e4SLinus Torvalds } 28601da177e4SLinus Torvalds 2861cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28621da177e4SLinus Torvalds { 2863cc314eefSLinus Torvalds struct page *page = cookie; 2864cc314eefSLinus Torvalds 2865cc314eefSLinus Torvalds if (page) { 28661da177e4SLinus Torvalds kunmap(page); 28671da177e4SLinus Torvalds page_cache_release(page); 28681da177e4SLinus Torvalds } 28691da177e4SLinus Torvalds } 28701da177e4SLinus Torvalds 287154566b2cSNick Piggin /* 287254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 287354566b2cSNick Piggin */ 287454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 28751da177e4SLinus Torvalds { 28761da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28770adb25d2SKirill Korotaev struct page *page; 2878afddba49SNick Piggin void *fsdata; 2879beb497abSDmitriy Monakhov int err; 28801da177e4SLinus Torvalds char *kaddr; 288154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 288254566b2cSNick Piggin if (nofs) 288354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 28841da177e4SLinus Torvalds 28857e53cac4SNeilBrown retry: 2886afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 288754566b2cSNick Piggin flags, &page, &fsdata); 28881da177e4SLinus Torvalds if (err) 2889afddba49SNick Piggin goto fail; 2890afddba49SNick Piggin 28911da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28921da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28931da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2894afddba49SNick Piggin 2895afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2896afddba49SNick Piggin page, fsdata); 28971da177e4SLinus Torvalds if (err < 0) 28981da177e4SLinus Torvalds goto fail; 2899afddba49SNick Piggin if (err < len-1) 2900afddba49SNick Piggin goto retry; 2901afddba49SNick Piggin 29021da177e4SLinus Torvalds mark_inode_dirty(inode); 29031da177e4SLinus Torvalds return 0; 29041da177e4SLinus Torvalds fail: 29051da177e4SLinus Torvalds return err; 29061da177e4SLinus Torvalds } 29071da177e4SLinus Torvalds 29080adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 29090adb25d2SKirill Korotaev { 29100adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 291154566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 29120adb25d2SKirill Korotaev } 29130adb25d2SKirill Korotaev 291492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 29151da177e4SLinus Torvalds .readlink = generic_readlink, 29161da177e4SLinus Torvalds .follow_link = page_follow_link_light, 29171da177e4SLinus Torvalds .put_link = page_put_link, 29181da177e4SLinus Torvalds }; 29191da177e4SLinus Torvalds 29202d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 29211da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 29221da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 29231da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 29241da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 29251da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 29261da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 29271da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 29281da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 29291da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 29300adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 29311da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 29321da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 29331da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2934d1811465SAl Viro EXPORT_SYMBOL(kern_path); 293516f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2936f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 29378c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 29381da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 29391da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 29401da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 29411da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 29421da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 29431da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 29441da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 29451da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 29461da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 29471da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 29481da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 29491da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 29501da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 29511da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2952