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/pagemap.h> 230eeca283SRobert Love #include <linux/fsnotify.h> 241da177e4SLinus Torvalds #include <linux/personality.h> 251da177e4SLinus Torvalds #include <linux/security.h> 266146f0d5SMimi Zohar #include <linux/ima.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 345ad4e53bSAl Viro #include <linux/fs_struct.h> 351da177e4SLinus Torvalds #include <asm/uaccess.h> 361da177e4SLinus Torvalds 37e81e3f4dSEric Paris #include "internal.h" 38e81e3f4dSEric Paris 391da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 401da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 411da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 421da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 431da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 441da177e4SLinus Torvalds * 451da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 461da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 471da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 481da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 491da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 501da177e4SLinus Torvalds * the special cases of the former code. 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 531da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 541da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 571da177e4SLinus Torvalds * resolution to correspond with current state of the code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 601da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 611da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 621da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 631da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 641da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 651da177e4SLinus Torvalds */ 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 681da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 691da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 701da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 711da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 721da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 731da177e4SLinus Torvalds * the name is a symlink pointing to a non-existant name. 741da177e4SLinus Torvalds * 751da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 761da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 771da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 781da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 791da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 801da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 811da177e4SLinus Torvalds * and in the old Linux semantics. 821da177e4SLinus Torvalds */ 831da177e4SLinus Torvalds 841da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 851da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 861da177e4SLinus Torvalds * 871da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 881da177e4SLinus Torvalds */ 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 911da177e4SLinus Torvalds * inside the path - always follow. 921da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 931da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 941da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 951da177e4SLinus Torvalds * otherwise - don't follow. 961da177e4SLinus Torvalds * (applied in that order). 971da177e4SLinus Torvalds * 981da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 991da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1001da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1011da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1021da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1031da177e4SLinus Torvalds */ 1041da177e4SLinus Torvalds /* 1051da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 106a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1071da177e4SLinus Torvalds * any extra contention... 1081da177e4SLinus Torvalds */ 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1111da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1121da177e4SLinus Torvalds * kernel data space before using them.. 1131da177e4SLinus Torvalds * 1141da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1151da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1161da177e4SLinus Torvalds */ 117858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1181da177e4SLinus Torvalds { 1191da177e4SLinus Torvalds int retval; 1201da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1231da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1241da177e4SLinus Torvalds return -EFAULT; 1251da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1261da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1271da177e4SLinus Torvalds } 1281da177e4SLinus Torvalds 1291da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1301da177e4SLinus Torvalds if (retval > 0) { 1311da177e4SLinus Torvalds if (retval < len) 1321da177e4SLinus Torvalds return 0; 1331da177e4SLinus Torvalds return -ENAMETOOLONG; 1341da177e4SLinus Torvalds } else if (!retval) 1351da177e4SLinus Torvalds retval = -ENOENT; 1361da177e4SLinus Torvalds return retval; 1371da177e4SLinus Torvalds } 1381da177e4SLinus Torvalds 1391da177e4SLinus Torvalds char * getname(const char __user * filename) 1401da177e4SLinus Torvalds { 1411da177e4SLinus Torvalds char *tmp, *result; 1421da177e4SLinus Torvalds 1431da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1441da177e4SLinus Torvalds tmp = __getname(); 1451da177e4SLinus Torvalds if (tmp) { 1461da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds result = tmp; 1491da177e4SLinus Torvalds if (retval < 0) { 1501da177e4SLinus Torvalds __putname(tmp); 1511da177e4SLinus Torvalds result = ERR_PTR(retval); 1521da177e4SLinus Torvalds } 1531da177e4SLinus Torvalds } 1541da177e4SLinus Torvalds audit_getname(result); 1551da177e4SLinus Torvalds return result; 1561da177e4SLinus Torvalds } 1571da177e4SLinus Torvalds 1581da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1591da177e4SLinus Torvalds void putname(const char *name) 1601da177e4SLinus Torvalds { 1615ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1621da177e4SLinus Torvalds audit_putname(name); 1631da177e4SLinus Torvalds else 1641da177e4SLinus Torvalds __putname(name); 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1671da177e4SLinus Torvalds #endif 1681da177e4SLinus Torvalds 1695909ccaaSLinus Torvalds /* 1705909ccaaSLinus Torvalds * This does basic POSIX ACL permission checking 1715909ccaaSLinus Torvalds */ 1725909ccaaSLinus Torvalds static int acl_permission_check(struct inode *inode, int mask, 1735909ccaaSLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 1745909ccaaSLinus Torvalds { 1755909ccaaSLinus Torvalds umode_t mode = inode->i_mode; 1765909ccaaSLinus Torvalds 1775909ccaaSLinus Torvalds mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 1785909ccaaSLinus Torvalds 1795909ccaaSLinus Torvalds if (current_fsuid() == inode->i_uid) 1805909ccaaSLinus Torvalds mode >>= 6; 1815909ccaaSLinus Torvalds else { 1825909ccaaSLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { 1835909ccaaSLinus Torvalds int error = check_acl(inode, mask); 1845909ccaaSLinus Torvalds if (error != -EAGAIN) 1855909ccaaSLinus Torvalds return error; 1865909ccaaSLinus Torvalds } 1875909ccaaSLinus Torvalds 1885909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 1895909ccaaSLinus Torvalds mode >>= 3; 1905909ccaaSLinus Torvalds } 1915909ccaaSLinus Torvalds 1925909ccaaSLinus Torvalds /* 1935909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 1945909ccaaSLinus Torvalds */ 1955909ccaaSLinus Torvalds if ((mask & ~mode) == 0) 1965909ccaaSLinus Torvalds return 0; 1975909ccaaSLinus Torvalds return -EACCES; 1985909ccaaSLinus Torvalds } 1991da177e4SLinus Torvalds 2001da177e4SLinus Torvalds /** 2011da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2021da177e4SLinus Torvalds * @inode: inode to check access rights for 2031da177e4SLinus Torvalds * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2041da177e4SLinus Torvalds * @check_acl: optional callback to check for Posix ACLs 2051da177e4SLinus Torvalds * 2061da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2071da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2081da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 2091da177e4SLinus Torvalds * are used for other things.. 2101da177e4SLinus Torvalds */ 2111da177e4SLinus Torvalds int generic_permission(struct inode *inode, int mask, 2121da177e4SLinus Torvalds int (*check_acl)(struct inode *inode, int mask)) 2131da177e4SLinus Torvalds { 2145909ccaaSLinus Torvalds int ret; 2151da177e4SLinus Torvalds 2161da177e4SLinus Torvalds /* 2175909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2181da177e4SLinus Torvalds */ 2195909ccaaSLinus Torvalds ret = acl_permission_check(inode, mask, check_acl); 2205909ccaaSLinus Torvalds if (ret != -EACCES) 2215909ccaaSLinus Torvalds return ret; 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds /* 2241da177e4SLinus Torvalds * Read/write DACs are always overridable. 2251da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2261da177e4SLinus Torvalds */ 227f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2281da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2291da177e4SLinus Torvalds return 0; 2301da177e4SLinus Torvalds 2311da177e4SLinus Torvalds /* 2321da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2331da177e4SLinus Torvalds */ 2347ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2351da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2361da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2371da177e4SLinus Torvalds return 0; 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds return -EACCES; 2401da177e4SLinus Torvalds } 2411da177e4SLinus Torvalds 242cb23beb5SChristoph Hellwig /** 243cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 244cb23beb5SChristoph Hellwig * @inode: inode to check permission on 245cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 246cb23beb5SChristoph Hellwig * 247cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 248cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 249cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 250cb23beb5SChristoph Hellwig * are used for other things. 251cb23beb5SChristoph Hellwig */ 252f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2531da177e4SLinus Torvalds { 254e6305c43SAl Viro int retval; 2551da177e4SLinus Torvalds 2561da177e4SLinus Torvalds if (mask & MAY_WRITE) { 25722590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2581da177e4SLinus Torvalds 2591da177e4SLinus Torvalds /* 2601da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2611da177e4SLinus Torvalds */ 2621da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2631da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2641da177e4SLinus Torvalds return -EROFS; 2651da177e4SLinus Torvalds 2661da177e4SLinus Torvalds /* 2671da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2681da177e4SLinus Torvalds */ 2691da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2701da177e4SLinus Torvalds return -EACCES; 2711da177e4SLinus Torvalds } 2721da177e4SLinus Torvalds 273acfa4380SAl Viro if (inode->i_op->permission) 274b77b0646SAl Viro retval = inode->i_op->permission(inode, mask); 275f696a365SMiklos Szeredi else 2765909ccaaSLinus Torvalds retval = generic_permission(inode, mask, inode->i_op->check_acl); 277f696a365SMiklos Szeredi 2781da177e4SLinus Torvalds if (retval) 2791da177e4SLinus Torvalds return retval; 2801da177e4SLinus Torvalds 28108ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 28208ce5f16SSerge E. Hallyn if (retval) 28308ce5f16SSerge E. Hallyn return retval; 28408ce5f16SSerge E. Hallyn 285e6305c43SAl Viro return security_inode_permission(inode, 286f418b006SStephen Smalley mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); 2871da177e4SLinus Torvalds } 2881da177e4SLinus Torvalds 289e4543eddSChristoph Hellwig /** 2908c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2918c744fb8SChristoph Hellwig * @file: file to check access rights for 2928c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2938c744fb8SChristoph Hellwig * 2948c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 2958c744fb8SChristoph Hellwig * file. 2968c744fb8SChristoph Hellwig * 2978c744fb8SChristoph Hellwig * Note: 2988c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 299cb23beb5SChristoph Hellwig * be done using inode_permission(). 3008c744fb8SChristoph Hellwig */ 3018c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3028c744fb8SChristoph Hellwig { 303f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3048c744fb8SChristoph Hellwig } 3058c744fb8SChristoph Hellwig 3061da177e4SLinus Torvalds /* 3071da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3081da177e4SLinus Torvalds * put_write_access() releases this write permission. 3091da177e4SLinus Torvalds * This is used for regular files. 3101da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3111da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3121da177e4SLinus Torvalds * can have the following values: 3131da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3141da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3151da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3161da177e4SLinus Torvalds * 3171da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3181da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3191da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3201da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3211da177e4SLinus Torvalds * the inode->i_lock spinlock. 3221da177e4SLinus Torvalds */ 3231da177e4SLinus Torvalds 3241da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3251da177e4SLinus Torvalds { 3261da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3271da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3281da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3291da177e4SLinus Torvalds return -ETXTBSY; 3301da177e4SLinus Torvalds } 3311da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3321da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds return 0; 3351da177e4SLinus Torvalds } 3361da177e4SLinus Torvalds 3371da177e4SLinus Torvalds int deny_write_access(struct file * file) 3381da177e4SLinus Torvalds { 3390f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3401da177e4SLinus Torvalds 3411da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3421da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3431da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3441da177e4SLinus Torvalds return -ETXTBSY; 3451da177e4SLinus Torvalds } 3461da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3471da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3481da177e4SLinus Torvalds 3491da177e4SLinus Torvalds return 0; 3501da177e4SLinus Torvalds } 3511da177e4SLinus Torvalds 3521d957f9bSJan Blunck /** 3535dd784d0SJan Blunck * path_get - get a reference to a path 3545dd784d0SJan Blunck * @path: path to get the reference to 3555dd784d0SJan Blunck * 3565dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3575dd784d0SJan Blunck */ 3585dd784d0SJan Blunck void path_get(struct path *path) 3595dd784d0SJan Blunck { 3605dd784d0SJan Blunck mntget(path->mnt); 3615dd784d0SJan Blunck dget(path->dentry); 3625dd784d0SJan Blunck } 3635dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3645dd784d0SJan Blunck 3655dd784d0SJan Blunck /** 3661d957f9bSJan Blunck * path_put - put a reference to a path 3671d957f9bSJan Blunck * @path: path to put the reference to 3681d957f9bSJan Blunck * 3691d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3701d957f9bSJan Blunck */ 3711d957f9bSJan Blunck void path_put(struct path *path) 3721da177e4SLinus Torvalds { 3731d957f9bSJan Blunck dput(path->dentry); 3741d957f9bSJan Blunck mntput(path->mnt); 3751da177e4SLinus Torvalds } 3761d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3771da177e4SLinus Torvalds 378834f2a4aSTrond Myklebust /** 379834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 380834f2a4aSTrond Myklebust * @nd: pointer to nameidata 381834f2a4aSTrond Myklebust */ 382834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 383834f2a4aSTrond Myklebust { 3840f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 385834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 386834f2a4aSTrond Myklebust else 387834f2a4aSTrond Myklebust fput(nd->intent.open.file); 388834f2a4aSTrond Myklebust } 389834f2a4aSTrond Myklebust 390bcdc5e01SIan Kent static inline struct dentry * 391bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 392bcdc5e01SIan Kent { 393bcdc5e01SIan Kent int status = dentry->d_op->d_revalidate(dentry, nd); 394bcdc5e01SIan Kent if (unlikely(status <= 0)) { 395bcdc5e01SIan Kent /* 396bcdc5e01SIan Kent * The dentry failed validation. 397bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 398bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 399bcdc5e01SIan Kent * to return a fail status. 400bcdc5e01SIan Kent */ 401bcdc5e01SIan Kent if (!status) { 402bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 403bcdc5e01SIan Kent dput(dentry); 404bcdc5e01SIan Kent dentry = NULL; 405bcdc5e01SIan Kent } 406bcdc5e01SIan Kent } else { 407bcdc5e01SIan Kent dput(dentry); 408bcdc5e01SIan Kent dentry = ERR_PTR(status); 409bcdc5e01SIan Kent } 410bcdc5e01SIan Kent } 411bcdc5e01SIan Kent return dentry; 412bcdc5e01SIan Kent } 413bcdc5e01SIan Kent 4141da177e4SLinus Torvalds /* 41539159de2SJeff Layton * force_reval_path - force revalidation of a dentry 41639159de2SJeff Layton * 41739159de2SJeff Layton * In some situations the path walking code will trust dentries without 41839159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 41939159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 42039159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 42139159de2SJeff Layton * a d_revalidate call before proceeding. 42239159de2SJeff Layton * 42339159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 42439159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 42539159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 42639159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 42739159de2SJeff Layton * to the path if necessary. 42839159de2SJeff Layton */ 42939159de2SJeff Layton static int 43039159de2SJeff Layton force_reval_path(struct path *path, struct nameidata *nd) 43139159de2SJeff Layton { 43239159de2SJeff Layton int status; 43339159de2SJeff Layton struct dentry *dentry = path->dentry; 43439159de2SJeff Layton 43539159de2SJeff Layton /* 43639159de2SJeff Layton * only check on filesystems where it's possible for the dentry to 43739159de2SJeff Layton * become stale. It's assumed that if this flag is set then the 43839159de2SJeff Layton * d_revalidate op will also be defined. 43939159de2SJeff Layton */ 44039159de2SJeff Layton if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) 44139159de2SJeff Layton return 0; 44239159de2SJeff Layton 44339159de2SJeff Layton status = dentry->d_op->d_revalidate(dentry, nd); 44439159de2SJeff Layton if (status > 0) 44539159de2SJeff Layton return 0; 44639159de2SJeff Layton 44739159de2SJeff Layton if (!status) { 44839159de2SJeff Layton d_invalidate(dentry); 44939159de2SJeff Layton status = -ESTALE; 45039159de2SJeff Layton } 45139159de2SJeff Layton return status; 45239159de2SJeff Layton } 45339159de2SJeff Layton 45439159de2SJeff Layton /* 455b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 456b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 457b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 4581da177e4SLinus Torvalds * 4591da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 460b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 4611da177e4SLinus Torvalds * complete permission check. 4621da177e4SLinus Torvalds */ 463b75b5086SAl Viro static int exec_permission(struct inode *inode) 4641da177e4SLinus Torvalds { 4655909ccaaSLinus Torvalds int ret; 4661da177e4SLinus Torvalds 467cb9179eaSLinus Torvalds if (inode->i_op->permission) { 4685909ccaaSLinus Torvalds ret = inode->i_op->permission(inode, MAY_EXEC); 469cb9179eaSLinus Torvalds if (!ret) 470cb9179eaSLinus Torvalds goto ok; 471cb9179eaSLinus Torvalds return ret; 472cb9179eaSLinus Torvalds } 4735909ccaaSLinus Torvalds ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl); 4745909ccaaSLinus Torvalds if (!ret) 4751da177e4SLinus Torvalds goto ok; 4761da177e4SLinus Torvalds 477f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 4781da177e4SLinus Torvalds goto ok; 4791da177e4SLinus Torvalds 4805909ccaaSLinus Torvalds return ret; 4811da177e4SLinus Torvalds ok: 482b77b0646SAl Viro return security_inode_permission(inode, MAY_EXEC); 4831da177e4SLinus Torvalds } 4841da177e4SLinus Torvalds 4852a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 4862a737871SAl Viro { 4872a737871SAl Viro if (!nd->root.mnt) { 4882a737871SAl Viro struct fs_struct *fs = current->fs; 4892a737871SAl Viro read_lock(&fs->lock); 4902a737871SAl Viro nd->root = fs->root; 4912a737871SAl Viro path_get(&nd->root); 4922a737871SAl Viro read_unlock(&fs->lock); 4932a737871SAl Viro } 4942a737871SAl Viro } 4952a737871SAl Viro 4966de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 4976de88d72SAl Viro 498f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 4991da177e4SLinus Torvalds { 5001da177e4SLinus Torvalds if (IS_ERR(link)) 5011da177e4SLinus Torvalds goto fail; 5021da177e4SLinus Torvalds 5031da177e4SLinus Torvalds if (*link == '/') { 5042a737871SAl Viro set_root(nd); 5051d957f9bSJan Blunck path_put(&nd->path); 5062a737871SAl Viro nd->path = nd->root; 5072a737871SAl Viro path_get(&nd->root); 5081da177e4SLinus Torvalds } 509b4091d5fSChristoph Hellwig 510def4af30SAl Viro return link_path_walk(link, nd); 5111da177e4SLinus Torvalds fail: 5121d957f9bSJan Blunck path_put(&nd->path); 5131da177e4SLinus Torvalds return PTR_ERR(link); 5141da177e4SLinus Torvalds } 5151da177e4SLinus Torvalds 5161d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 517051d3812SIan Kent { 518051d3812SIan Kent dput(path->dentry); 5194ac91378SJan Blunck if (path->mnt != nd->path.mnt) 520051d3812SIan Kent mntput(path->mnt); 521051d3812SIan Kent } 522051d3812SIan Kent 523051d3812SIan Kent static inline void path_to_nameidata(struct path *path, struct nameidata *nd) 524051d3812SIan Kent { 5254ac91378SJan Blunck dput(nd->path.dentry); 5264ac91378SJan Blunck if (nd->path.mnt != path->mnt) 5274ac91378SJan Blunck mntput(nd->path.mnt); 5284ac91378SJan Blunck nd->path.mnt = path->mnt; 5294ac91378SJan Blunck nd->path.dentry = path->dentry; 530051d3812SIan Kent } 531051d3812SIan Kent 532def4af30SAl Viro static __always_inline int 533def4af30SAl Viro __do_follow_link(struct path *path, struct nameidata *nd, void **p) 5341da177e4SLinus Torvalds { 5351da177e4SLinus Torvalds int error; 536cd4e91d3SAl Viro struct dentry *dentry = path->dentry; 5371da177e4SLinus Torvalds 538d671a1cbSAl Viro touch_atime(path->mnt, dentry); 5391da177e4SLinus Torvalds nd_set_link(nd, NULL); 540cd4e91d3SAl Viro 5414ac91378SJan Blunck if (path->mnt != nd->path.mnt) { 542051d3812SIan Kent path_to_nameidata(path, nd); 543051d3812SIan Kent dget(dentry); 544051d3812SIan Kent } 545cd4e91d3SAl Viro mntget(path->mnt); 54686acdca1SAl Viro nd->last_type = LAST_BIND; 547def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 548def4af30SAl Viro error = PTR_ERR(*p); 549def4af30SAl Viro if (!IS_ERR(*p)) { 5501da177e4SLinus Torvalds char *s = nd_get_link(nd); 551cc314eefSLinus Torvalds error = 0; 5521da177e4SLinus Torvalds if (s) 5531da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 55439159de2SJeff Layton else if (nd->last_type == LAST_BIND) { 55539159de2SJeff Layton error = force_reval_path(&nd->path, nd); 55639159de2SJeff Layton if (error) 55739159de2SJeff Layton path_put(&nd->path); 55839159de2SJeff Layton } 5591da177e4SLinus Torvalds } 5601da177e4SLinus Torvalds return error; 5611da177e4SLinus Torvalds } 5621da177e4SLinus Torvalds 5631da177e4SLinus Torvalds /* 5641da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 5651da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 5661da177e4SLinus Torvalds * 5671da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 5681da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 5691da177e4SLinus Torvalds */ 57090ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 5711da177e4SLinus Torvalds { 572def4af30SAl Viro void *cookie; 5731da177e4SLinus Torvalds int err = -ELOOP; 5741da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 5751da177e4SLinus Torvalds goto loop; 5761da177e4SLinus Torvalds if (current->total_link_count >= 40) 5771da177e4SLinus Torvalds goto loop; 5781da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 5791da177e4SLinus Torvalds cond_resched(); 58090ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 5811da177e4SLinus Torvalds if (err) 5821da177e4SLinus Torvalds goto loop; 5831da177e4SLinus Torvalds current->link_count++; 5841da177e4SLinus Torvalds current->total_link_count++; 5851da177e4SLinus Torvalds nd->depth++; 586def4af30SAl Viro err = __do_follow_link(path, nd, &cookie); 587def4af30SAl Viro if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link) 588def4af30SAl Viro path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie); 589258fa999SAl Viro path_put(path); 5901da177e4SLinus Torvalds current->link_count--; 5911da177e4SLinus Torvalds nd->depth--; 5921da177e4SLinus Torvalds return err; 5931da177e4SLinus Torvalds loop: 5941d957f9bSJan Blunck path_put_conditional(path, nd); 5951d957f9bSJan Blunck path_put(&nd->path); 5961da177e4SLinus Torvalds return err; 5971da177e4SLinus Torvalds } 5981da177e4SLinus Torvalds 599bab77ebfSAl Viro int follow_up(struct path *path) 6001da177e4SLinus Torvalds { 6011da177e4SLinus Torvalds struct vfsmount *parent; 6021da177e4SLinus Torvalds struct dentry *mountpoint; 6031da177e4SLinus Torvalds spin_lock(&vfsmount_lock); 604bab77ebfSAl Viro parent = path->mnt->mnt_parent; 605bab77ebfSAl Viro if (parent == path->mnt) { 6061da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 6071da177e4SLinus Torvalds return 0; 6081da177e4SLinus Torvalds } 6091da177e4SLinus Torvalds mntget(parent); 610bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 6111da177e4SLinus Torvalds spin_unlock(&vfsmount_lock); 612bab77ebfSAl Viro dput(path->dentry); 613bab77ebfSAl Viro path->dentry = mountpoint; 614bab77ebfSAl Viro mntput(path->mnt); 615bab77ebfSAl Viro path->mnt = parent; 6161da177e4SLinus Torvalds return 1; 6171da177e4SLinus Torvalds } 6181da177e4SLinus Torvalds 6191da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6201da177e4SLinus Torvalds * namespace.c 6211da177e4SLinus Torvalds */ 622463ffb2eSAl Viro static int __follow_mount(struct path *path) 623463ffb2eSAl Viro { 624463ffb2eSAl Viro int res = 0; 625463ffb2eSAl Viro while (d_mountpoint(path->dentry)) { 6261c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 627463ffb2eSAl Viro if (!mounted) 628463ffb2eSAl Viro break; 629463ffb2eSAl Viro dput(path->dentry); 630463ffb2eSAl Viro if (res) 631463ffb2eSAl Viro mntput(path->mnt); 632463ffb2eSAl Viro path->mnt = mounted; 633463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 634463ffb2eSAl Viro res = 1; 635463ffb2eSAl Viro } 636463ffb2eSAl Viro return res; 637463ffb2eSAl Viro } 638463ffb2eSAl Viro 63979ed0226SAl Viro static void follow_mount(struct path *path) 6401da177e4SLinus Torvalds { 64179ed0226SAl Viro while (d_mountpoint(path->dentry)) { 6421c755af4SAl Viro struct vfsmount *mounted = lookup_mnt(path); 6431da177e4SLinus Torvalds if (!mounted) 6441da177e4SLinus Torvalds break; 64579ed0226SAl Viro dput(path->dentry); 64679ed0226SAl Viro mntput(path->mnt); 64779ed0226SAl Viro path->mnt = mounted; 64879ed0226SAl Viro path->dentry = dget(mounted->mnt_root); 6491da177e4SLinus Torvalds } 6501da177e4SLinus Torvalds } 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds /* no need for dcache_lock, as serialization is taken care in 6531da177e4SLinus Torvalds * namespace.c 6541da177e4SLinus Torvalds */ 6559393bd07SAl Viro int follow_down(struct path *path) 6561da177e4SLinus Torvalds { 6571da177e4SLinus Torvalds struct vfsmount *mounted; 6581da177e4SLinus Torvalds 6591c755af4SAl Viro mounted = lookup_mnt(path); 6601da177e4SLinus Torvalds if (mounted) { 6619393bd07SAl Viro dput(path->dentry); 6629393bd07SAl Viro mntput(path->mnt); 6639393bd07SAl Viro path->mnt = mounted; 6649393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 6651da177e4SLinus Torvalds return 1; 6661da177e4SLinus Torvalds } 6671da177e4SLinus Torvalds return 0; 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds 670f1662356SArjan van de Ven static __always_inline void follow_dotdot(struct nameidata *nd) 6711da177e4SLinus Torvalds { 6722a737871SAl Viro set_root(nd); 673e518ddb7SAndreas Mohr 6741da177e4SLinus Torvalds while(1) { 6754ac91378SJan Blunck struct dentry *old = nd->path.dentry; 6761da177e4SLinus Torvalds 6772a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 6782a737871SAl Viro nd->path.mnt == nd->root.mnt) { 6791da177e4SLinus Torvalds break; 6801da177e4SLinus Torvalds } 6814ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 6823088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 6833088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 6841da177e4SLinus Torvalds dput(old); 6851da177e4SLinus Torvalds break; 6861da177e4SLinus Torvalds } 6873088dd70SAl Viro if (!follow_up(&nd->path)) 6881da177e4SLinus Torvalds break; 6891da177e4SLinus Torvalds } 69079ed0226SAl Viro follow_mount(&nd->path); 6911da177e4SLinus Torvalds } 6921da177e4SLinus Torvalds 6931da177e4SLinus Torvalds /* 6941da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 6951da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 6961da177e4SLinus Torvalds * It _is_ time-critical. 6971da177e4SLinus Torvalds */ 6981da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 6991da177e4SLinus Torvalds struct path *path) 7001da177e4SLinus Torvalds { 7014ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 7026e6b1bd1SAl Viro struct dentry *dentry, *parent; 7036e6b1bd1SAl Viro struct inode *dir; 7043cac260aSAl Viro /* 7053cac260aSAl Viro * See if the low-level filesystem might want 7063cac260aSAl Viro * to use its own hash.. 7073cac260aSAl Viro */ 7083cac260aSAl Viro if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { 7093cac260aSAl Viro int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name); 7103cac260aSAl Viro if (err < 0) 7113cac260aSAl Viro return err; 7123cac260aSAl Viro } 7131da177e4SLinus Torvalds 7143cac260aSAl Viro dentry = __d_lookup(nd->path.dentry, name); 7151da177e4SLinus Torvalds if (!dentry) 7161da177e4SLinus Torvalds goto need_lookup; 7171da177e4SLinus Torvalds if (dentry->d_op && dentry->d_op->d_revalidate) 7181da177e4SLinus Torvalds goto need_revalidate; 7191da177e4SLinus Torvalds done: 7201da177e4SLinus Torvalds path->mnt = mnt; 7211da177e4SLinus Torvalds path->dentry = dentry; 722634ee701SAl Viro __follow_mount(path); 7231da177e4SLinus Torvalds return 0; 7241da177e4SLinus Torvalds 7251da177e4SLinus Torvalds need_lookup: 7266e6b1bd1SAl Viro parent = nd->path.dentry; 7276e6b1bd1SAl Viro dir = parent->d_inode; 7286e6b1bd1SAl Viro 7296e6b1bd1SAl Viro mutex_lock(&dir->i_mutex); 7306e6b1bd1SAl Viro /* 7316e6b1bd1SAl Viro * First re-do the cached lookup just in case it was created 7326e6b1bd1SAl Viro * while we waited for the directory semaphore.. 7336e6b1bd1SAl Viro * 7346e6b1bd1SAl Viro * FIXME! This could use version numbering or similar to 7356e6b1bd1SAl Viro * avoid unnecessary cache lookups. 7366e6b1bd1SAl Viro * 7376e6b1bd1SAl Viro * The "dcache_lock" is purely to protect the RCU list walker 7386e6b1bd1SAl Viro * from concurrent renames at this point (we mustn't get false 7396e6b1bd1SAl Viro * negatives from the RCU list walk here, unlike the optimistic 7406e6b1bd1SAl Viro * fast walk). 7416e6b1bd1SAl Viro * 7426e6b1bd1SAl Viro * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup 7436e6b1bd1SAl Viro */ 7446e6b1bd1SAl Viro dentry = d_lookup(parent, name); 7456e6b1bd1SAl Viro if (!dentry) { 7466e6b1bd1SAl Viro struct dentry *new; 7476e6b1bd1SAl Viro 7486e6b1bd1SAl Viro /* Don't create child dentry for a dead directory. */ 7496e6b1bd1SAl Viro dentry = ERR_PTR(-ENOENT); 7506e6b1bd1SAl Viro if (IS_DEADDIR(dir)) 7516e6b1bd1SAl Viro goto out_unlock; 7526e6b1bd1SAl Viro 7536e6b1bd1SAl Viro new = d_alloc(parent, name); 7546e6b1bd1SAl Viro dentry = ERR_PTR(-ENOMEM); 7556e6b1bd1SAl Viro if (new) { 7566e6b1bd1SAl Viro dentry = dir->i_op->lookup(dir, new, nd); 7576e6b1bd1SAl Viro if (dentry) 7586e6b1bd1SAl Viro dput(new); 7596e6b1bd1SAl Viro else 7606e6b1bd1SAl Viro dentry = new; 7616e6b1bd1SAl Viro } 7626e6b1bd1SAl Viro out_unlock: 7636e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 7646e6b1bd1SAl Viro if (IS_ERR(dentry)) 7656e6b1bd1SAl Viro goto fail; 7666e6b1bd1SAl Viro goto done; 7676e6b1bd1SAl Viro } 7686e6b1bd1SAl Viro 7696e6b1bd1SAl Viro /* 7706e6b1bd1SAl Viro * Uhhuh! Nasty case: the cache was re-populated while 7716e6b1bd1SAl Viro * we waited on the semaphore. Need to revalidate. 7726e6b1bd1SAl Viro */ 7736e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 7746e6b1bd1SAl Viro if (dentry->d_op && dentry->d_op->d_revalidate) { 7756e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 7766e6b1bd1SAl Viro if (!dentry) 7776e6b1bd1SAl Viro dentry = ERR_PTR(-ENOENT); 7786e6b1bd1SAl Viro } 7791da177e4SLinus Torvalds if (IS_ERR(dentry)) 7801da177e4SLinus Torvalds goto fail; 7811da177e4SLinus Torvalds goto done; 7821da177e4SLinus Torvalds 7831da177e4SLinus Torvalds need_revalidate: 784bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 785bcdc5e01SIan Kent if (!dentry) 7861da177e4SLinus Torvalds goto need_lookup; 787bcdc5e01SIan Kent if (IS_ERR(dentry)) 788bcdc5e01SIan Kent goto fail; 789bcdc5e01SIan Kent goto done; 7901da177e4SLinus Torvalds 7911da177e4SLinus Torvalds fail: 7921da177e4SLinus Torvalds return PTR_ERR(dentry); 7931da177e4SLinus Torvalds } 7941da177e4SLinus Torvalds 7951da177e4SLinus Torvalds /* 796ac278a9cSAl Viro * This is a temporary kludge to deal with "automount" symlinks; proper 797ac278a9cSAl Viro * solution is to trigger them on follow_mount(), so that do_lookup() 798ac278a9cSAl Viro * would DTRT. To be killed before 2.6.34-final. 799ac278a9cSAl Viro */ 800ac278a9cSAl Viro static inline int follow_on_final(struct inode *inode, unsigned lookup_flags) 801ac278a9cSAl Viro { 802ac278a9cSAl Viro return inode && unlikely(inode->i_op->follow_link) && 803ac278a9cSAl Viro ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode)); 804ac278a9cSAl Viro } 805ac278a9cSAl Viro 806ac278a9cSAl Viro /* 8071da177e4SLinus Torvalds * Name resolution. 808ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 809ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 8101da177e4SLinus Torvalds * 811ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 812ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 8131da177e4SLinus Torvalds */ 8146de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 8151da177e4SLinus Torvalds { 8161da177e4SLinus Torvalds struct path next; 8171da177e4SLinus Torvalds struct inode *inode; 8181da177e4SLinus Torvalds int err; 8191da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 8201da177e4SLinus Torvalds 8211da177e4SLinus Torvalds while (*name=='/') 8221da177e4SLinus Torvalds name++; 8231da177e4SLinus Torvalds if (!*name) 8241da177e4SLinus Torvalds goto return_reval; 8251da177e4SLinus Torvalds 8264ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8271da177e4SLinus Torvalds if (nd->depth) 828f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 8291da177e4SLinus Torvalds 8301da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 8311da177e4SLinus Torvalds for(;;) { 8321da177e4SLinus Torvalds unsigned long hash; 8331da177e4SLinus Torvalds struct qstr this; 8341da177e4SLinus Torvalds unsigned int c; 8351da177e4SLinus Torvalds 836cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 837b75b5086SAl Viro err = exec_permission(inode); 8381da177e4SLinus Torvalds if (err) 8391da177e4SLinus Torvalds break; 8401da177e4SLinus Torvalds 8411da177e4SLinus Torvalds this.name = name; 8421da177e4SLinus Torvalds c = *(const unsigned char *)name; 8431da177e4SLinus Torvalds 8441da177e4SLinus Torvalds hash = init_name_hash(); 8451da177e4SLinus Torvalds do { 8461da177e4SLinus Torvalds name++; 8471da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 8481da177e4SLinus Torvalds c = *(const unsigned char *)name; 8491da177e4SLinus Torvalds } while (c && (c != '/')); 8501da177e4SLinus Torvalds this.len = name - (const char *) this.name; 8511da177e4SLinus Torvalds this.hash = end_name_hash(hash); 8521da177e4SLinus Torvalds 8531da177e4SLinus Torvalds /* remove trailing slashes? */ 8541da177e4SLinus Torvalds if (!c) 8551da177e4SLinus Torvalds goto last_component; 8561da177e4SLinus Torvalds while (*++name == '/'); 8571da177e4SLinus Torvalds if (!*name) 8581da177e4SLinus Torvalds goto last_with_slashes; 8591da177e4SLinus Torvalds 8601da177e4SLinus Torvalds /* 8611da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 8621da177e4SLinus Torvalds * to be able to know about the current root directory and 8631da177e4SLinus Torvalds * parent relationships. 8641da177e4SLinus Torvalds */ 8651da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 8661da177e4SLinus Torvalds default: 8671da177e4SLinus Torvalds break; 8681da177e4SLinus Torvalds case 2: 8691da177e4SLinus Torvalds if (this.name[1] != '.') 8701da177e4SLinus Torvalds break; 87158c465ebSAl Viro follow_dotdot(nd); 8724ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8731da177e4SLinus Torvalds /* fallthrough */ 8741da177e4SLinus Torvalds case 1: 8751da177e4SLinus Torvalds continue; 8761da177e4SLinus Torvalds } 8771da177e4SLinus Torvalds /* This does the actual lookups.. */ 8781da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 8791da177e4SLinus Torvalds if (err) 8801da177e4SLinus Torvalds break; 8811da177e4SLinus Torvalds 8821da177e4SLinus Torvalds err = -ENOENT; 8831da177e4SLinus Torvalds inode = next.dentry->d_inode; 8841da177e4SLinus Torvalds if (!inode) 8851da177e4SLinus Torvalds goto out_dput; 8861da177e4SLinus Torvalds 8871da177e4SLinus Torvalds if (inode->i_op->follow_link) { 88890ebe565SAl Viro err = do_follow_link(&next, nd); 8891da177e4SLinus Torvalds if (err) 8901da177e4SLinus Torvalds goto return_err; 8911da177e4SLinus Torvalds err = -ENOENT; 8924ac91378SJan Blunck inode = nd->path.dentry->d_inode; 8931da177e4SLinus Torvalds if (!inode) 8941da177e4SLinus Torvalds break; 89509dd17d3SMiklos Szeredi } else 89609dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 8971da177e4SLinus Torvalds err = -ENOTDIR; 8981da177e4SLinus Torvalds if (!inode->i_op->lookup) 8991da177e4SLinus Torvalds break; 9001da177e4SLinus Torvalds continue; 9011da177e4SLinus Torvalds /* here ends the main loop */ 9021da177e4SLinus Torvalds 9031da177e4SLinus Torvalds last_with_slashes: 9041da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 9051da177e4SLinus Torvalds last_component: 906f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 907f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 9081da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 9091da177e4SLinus Torvalds goto lookup_parent; 9101da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 9111da177e4SLinus Torvalds default: 9121da177e4SLinus Torvalds break; 9131da177e4SLinus Torvalds case 2: 9141da177e4SLinus Torvalds if (this.name[1] != '.') 9151da177e4SLinus Torvalds break; 91658c465ebSAl Viro follow_dotdot(nd); 9174ac91378SJan Blunck inode = nd->path.dentry->d_inode; 9181da177e4SLinus Torvalds /* fallthrough */ 9191da177e4SLinus Torvalds case 1: 9201da177e4SLinus Torvalds goto return_reval; 9211da177e4SLinus Torvalds } 9221da177e4SLinus Torvalds err = do_lookup(nd, &this, &next); 9231da177e4SLinus Torvalds if (err) 9241da177e4SLinus Torvalds break; 9251da177e4SLinus Torvalds inode = next.dentry->d_inode; 926ac278a9cSAl Viro if (follow_on_final(inode, lookup_flags)) { 92790ebe565SAl Viro err = do_follow_link(&next, nd); 9281da177e4SLinus Torvalds if (err) 9291da177e4SLinus Torvalds goto return_err; 9304ac91378SJan Blunck inode = nd->path.dentry->d_inode; 93109dd17d3SMiklos Szeredi } else 93209dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 9331da177e4SLinus Torvalds err = -ENOENT; 9341da177e4SLinus Torvalds if (!inode) 9351da177e4SLinus Torvalds break; 9361da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 9371da177e4SLinus Torvalds err = -ENOTDIR; 938acfa4380SAl Viro if (!inode->i_op->lookup) 9391da177e4SLinus Torvalds break; 9401da177e4SLinus Torvalds } 9411da177e4SLinus Torvalds goto return_base; 9421da177e4SLinus Torvalds lookup_parent: 9431da177e4SLinus Torvalds nd->last = this; 9441da177e4SLinus Torvalds nd->last_type = LAST_NORM; 9451da177e4SLinus Torvalds if (this.name[0] != '.') 9461da177e4SLinus Torvalds goto return_base; 9471da177e4SLinus Torvalds if (this.len == 1) 9481da177e4SLinus Torvalds nd->last_type = LAST_DOT; 9491da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 9501da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 9511da177e4SLinus Torvalds else 9521da177e4SLinus Torvalds goto return_base; 9531da177e4SLinus Torvalds return_reval: 9541da177e4SLinus Torvalds /* 9551da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 9561da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 9571da177e4SLinus Torvalds */ 9584ac91378SJan Blunck if (nd->path.dentry && nd->path.dentry->d_sb && 9594ac91378SJan Blunck (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { 9601da177e4SLinus Torvalds err = -ESTALE; 9611da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 9624ac91378SJan Blunck if (!nd->path.dentry->d_op->d_revalidate( 9634ac91378SJan Blunck nd->path.dentry, nd)) 9641da177e4SLinus Torvalds break; 9651da177e4SLinus Torvalds } 9661da177e4SLinus Torvalds return_base: 9671da177e4SLinus Torvalds return 0; 9681da177e4SLinus Torvalds out_dput: 9691d957f9bSJan Blunck path_put_conditional(&next, nd); 9701da177e4SLinus Torvalds break; 9711da177e4SLinus Torvalds } 9721d957f9bSJan Blunck path_put(&nd->path); 9731da177e4SLinus Torvalds return_err: 9741da177e4SLinus Torvalds return err; 9751da177e4SLinus Torvalds } 9761da177e4SLinus Torvalds 977fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 9781da177e4SLinus Torvalds { 9796de88d72SAl Viro struct path save = nd->path; 9806de88d72SAl Viro int result; 9816de88d72SAl Viro 9821da177e4SLinus Torvalds current->total_link_count = 0; 9836de88d72SAl Viro 9846de88d72SAl Viro /* make sure the stuff we saved doesn't go away */ 9856de88d72SAl Viro path_get(&save); 9866de88d72SAl Viro 9876de88d72SAl Viro result = link_path_walk(name, nd); 9886de88d72SAl Viro if (result == -ESTALE) { 9896de88d72SAl Viro /* nd->path had been dropped */ 9906de88d72SAl Viro current->total_link_count = 0; 9916de88d72SAl Viro nd->path = save; 9926de88d72SAl Viro path_get(&nd->path); 9936de88d72SAl Viro nd->flags |= LOOKUP_REVAL; 9946de88d72SAl Viro result = link_path_walk(name, nd); 9956de88d72SAl Viro } 9966de88d72SAl Viro 9976de88d72SAl Viro path_put(&save); 9986de88d72SAl Viro 9996de88d72SAl Viro return result; 10001da177e4SLinus Torvalds } 10011da177e4SLinus Torvalds 10029b4a9b14SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 10031da177e4SLinus Torvalds { 1004ea3834d9SPrasanna Meda int retval = 0; 1005170aa3d0SUlrich Drepper int fput_needed; 1006170aa3d0SUlrich Drepper struct file *file; 10071da177e4SLinus Torvalds 10081da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 10091da177e4SLinus Torvalds nd->flags = flags; 10101da177e4SLinus Torvalds nd->depth = 0; 10112a737871SAl Viro nd->root.mnt = NULL; 10121da177e4SLinus Torvalds 10131da177e4SLinus Torvalds if (*name=='/') { 10142a737871SAl Viro set_root(nd); 10152a737871SAl Viro nd->path = nd->root; 10162a737871SAl Viro path_get(&nd->root); 10175590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 10182a737871SAl Viro struct fs_struct *fs = current->fs; 1019e518ddb7SAndreas Mohr read_lock(&fs->lock); 10206ac08c39SJan Blunck nd->path = fs->pwd; 10216ac08c39SJan Blunck path_get(&fs->pwd); 1022e518ddb7SAndreas Mohr read_unlock(&fs->lock); 10235590ff0dSUlrich Drepper } else { 10245590ff0dSUlrich Drepper struct dentry *dentry; 10255590ff0dSUlrich Drepper 10265590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 10275590ff0dSUlrich Drepper retval = -EBADF; 1028170aa3d0SUlrich Drepper if (!file) 10296d09bb62STrond Myklebust goto out_fail; 10305590ff0dSUlrich Drepper 10310f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 10325590ff0dSUlrich Drepper 10335590ff0dSUlrich Drepper retval = -ENOTDIR; 1034170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 10356d09bb62STrond Myklebust goto fput_fail; 10365590ff0dSUlrich Drepper 10375590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1038170aa3d0SUlrich Drepper if (retval) 10396d09bb62STrond Myklebust goto fput_fail; 10405590ff0dSUlrich Drepper 10415dd784d0SJan Blunck nd->path = file->f_path; 10425dd784d0SJan Blunck path_get(&file->f_path); 10435590ff0dSUlrich Drepper 10445590ff0dSUlrich Drepper fput_light(file, fput_needed); 10451da177e4SLinus Torvalds } 10469b4a9b14SAl Viro return 0; 10472dfdd266SJosef 'Jeff' Sipek 10489b4a9b14SAl Viro fput_fail: 10499b4a9b14SAl Viro fput_light(file, fput_needed); 10509b4a9b14SAl Viro out_fail: 10519b4a9b14SAl Viro return retval; 10529b4a9b14SAl Viro } 10539b4a9b14SAl Viro 10549b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 10559b4a9b14SAl Viro static int do_path_lookup(int dfd, const char *name, 10569b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 10579b4a9b14SAl Viro { 10589b4a9b14SAl Viro int retval = path_init(dfd, name, flags, nd); 10599b4a9b14SAl Viro if (!retval) 10602dfdd266SJosef 'Jeff' Sipek retval = path_walk(name, nd); 10614ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 10624ac91378SJan Blunck nd->path.dentry->d_inode)) 10634ac91378SJan Blunck audit_inode(name, nd->path.dentry); 10642a737871SAl Viro if (nd->root.mnt) { 10652a737871SAl Viro path_put(&nd->root); 10662a737871SAl Viro nd->root.mnt = NULL; 10672a737871SAl Viro } 1068170aa3d0SUlrich Drepper return retval; 10691da177e4SLinus Torvalds } 10701da177e4SLinus Torvalds 1071fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 10725590ff0dSUlrich Drepper struct nameidata *nd) 10735590ff0dSUlrich Drepper { 10745590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 10755590ff0dSUlrich Drepper } 10765590ff0dSUlrich Drepper 1077d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1078d1811465SAl Viro { 1079d1811465SAl Viro struct nameidata nd; 1080d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1081d1811465SAl Viro if (!res) 1082d1811465SAl Viro *path = nd.path; 1083d1811465SAl Viro return res; 1084d1811465SAl Viro } 1085d1811465SAl Viro 108616f18200SJosef 'Jeff' Sipek /** 108716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 108816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 108916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 109016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 109116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 109216f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 109316f18200SJosef 'Jeff' Sipek */ 109416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 109516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 109616f18200SJosef 'Jeff' Sipek struct nameidata *nd) 109716f18200SJosef 'Jeff' Sipek { 109816f18200SJosef 'Jeff' Sipek int retval; 109916f18200SJosef 'Jeff' Sipek 110016f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 110116f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 110216f18200SJosef 'Jeff' Sipek nd->flags = flags; 110316f18200SJosef 'Jeff' Sipek nd->depth = 0; 110416f18200SJosef 'Jeff' Sipek 1105c8e7f449SJan Blunck nd->path.dentry = dentry; 1106c8e7f449SJan Blunck nd->path.mnt = mnt; 1107c8e7f449SJan Blunck path_get(&nd->path); 11085b857119SAl Viro nd->root = nd->path; 11095b857119SAl Viro path_get(&nd->root); 111016f18200SJosef 'Jeff' Sipek 111116f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 11124ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 11134ac91378SJan Blunck nd->path.dentry->d_inode)) 11144ac91378SJan Blunck audit_inode(name, nd->path.dentry); 111516f18200SJosef 'Jeff' Sipek 11162a737871SAl Viro path_put(&nd->root); 11172a737871SAl Viro nd->root.mnt = NULL; 111816f18200SJosef 'Jeff' Sipek 11192a737871SAl Viro return retval; 112016f18200SJosef 'Jeff' Sipek } 112116f18200SJosef 'Jeff' Sipek 1122eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1123eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 11241da177e4SLinus Torvalds { 11251da177e4SLinus Torvalds struct dentry *dentry; 11261da177e4SLinus Torvalds struct inode *inode; 11271da177e4SLinus Torvalds int err; 11281da177e4SLinus Torvalds 11291da177e4SLinus Torvalds inode = base->d_inode; 11301da177e4SLinus Torvalds 11311da177e4SLinus Torvalds /* 11321da177e4SLinus Torvalds * See if the low-level filesystem might want 11331da177e4SLinus Torvalds * to use its own hash.. 11341da177e4SLinus Torvalds */ 11351da177e4SLinus Torvalds if (base->d_op && base->d_op->d_hash) { 11361da177e4SLinus Torvalds err = base->d_op->d_hash(base, name); 11371da177e4SLinus Torvalds dentry = ERR_PTR(err); 11381da177e4SLinus Torvalds if (err < 0) 11391da177e4SLinus Torvalds goto out; 11401da177e4SLinus Torvalds } 11411da177e4SLinus Torvalds 11426e6b1bd1SAl Viro dentry = __d_lookup(base, name); 11436e6b1bd1SAl Viro 11446e6b1bd1SAl Viro /* lockess __d_lookup may fail due to concurrent d_move() 11456e6b1bd1SAl Viro * in some unrelated directory, so try with d_lookup 11466e6b1bd1SAl Viro */ 11476e6b1bd1SAl Viro if (!dentry) 11486e6b1bd1SAl Viro dentry = d_lookup(base, name); 11496e6b1bd1SAl Viro 11506e6b1bd1SAl Viro if (dentry && dentry->d_op && dentry->d_op->d_revalidate) 11516e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 11526e6b1bd1SAl Viro 11531da177e4SLinus Torvalds if (!dentry) { 1154d70b67c8SMiklos Szeredi struct dentry *new; 1155d70b67c8SMiklos Szeredi 1156d70b67c8SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 1157d70b67c8SMiklos Szeredi dentry = ERR_PTR(-ENOENT); 1158d70b67c8SMiklos Szeredi if (IS_DEADDIR(inode)) 1159d70b67c8SMiklos Szeredi goto out; 1160d70b67c8SMiklos Szeredi 1161d70b67c8SMiklos Szeredi new = d_alloc(base, name); 11621da177e4SLinus Torvalds dentry = ERR_PTR(-ENOMEM); 11631da177e4SLinus Torvalds if (!new) 11641da177e4SLinus Torvalds goto out; 11651da177e4SLinus Torvalds dentry = inode->i_op->lookup(inode, new, nd); 11661da177e4SLinus Torvalds if (!dentry) 11671da177e4SLinus Torvalds dentry = new; 11681da177e4SLinus Torvalds else 11691da177e4SLinus Torvalds dput(new); 11701da177e4SLinus Torvalds } 11711da177e4SLinus Torvalds out: 11721da177e4SLinus Torvalds return dentry; 11731da177e4SLinus Torvalds } 11741da177e4SLinus Torvalds 1175057f6c01SJames Morris /* 1176057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1177057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1178057f6c01SJames Morris * SMP-safe. 1179057f6c01SJames Morris */ 1180a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 11811da177e4SLinus Torvalds { 1182eead1911SChristoph Hellwig int err; 1183eead1911SChristoph Hellwig 1184b75b5086SAl Viro err = exec_permission(nd->path.dentry->d_inode); 1185eead1911SChristoph Hellwig if (err) 1186eead1911SChristoph Hellwig return ERR_PTR(err); 11874ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 11881da177e4SLinus Torvalds } 11891da177e4SLinus Torvalds 1190eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1191eead1911SChristoph Hellwig struct dentry *base, int len) 11921da177e4SLinus Torvalds { 11931da177e4SLinus Torvalds unsigned long hash; 11941da177e4SLinus Torvalds unsigned int c; 11951da177e4SLinus Torvalds 1196057f6c01SJames Morris this->name = name; 1197057f6c01SJames Morris this->len = len; 11981da177e4SLinus Torvalds if (!len) 1199057f6c01SJames Morris return -EACCES; 12001da177e4SLinus Torvalds 12011da177e4SLinus Torvalds hash = init_name_hash(); 12021da177e4SLinus Torvalds while (len--) { 12031da177e4SLinus Torvalds c = *(const unsigned char *)name++; 12041da177e4SLinus Torvalds if (c == '/' || c == '\0') 1205057f6c01SJames Morris return -EACCES; 12061da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 12071da177e4SLinus Torvalds } 1208057f6c01SJames Morris this->hash = end_name_hash(hash); 1209057f6c01SJames Morris return 0; 1210057f6c01SJames Morris } 12111da177e4SLinus Torvalds 1212eead1911SChristoph Hellwig /** 1213a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1214eead1911SChristoph Hellwig * @name: pathname component to lookup 1215eead1911SChristoph Hellwig * @base: base directory to lookup from 1216eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1217eead1911SChristoph Hellwig * 1218a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1219a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1220eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1221eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1222eead1911SChristoph Hellwig */ 1223057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1224057f6c01SJames Morris { 1225057f6c01SJames Morris int err; 1226057f6c01SJames Morris struct qstr this; 1227057f6c01SJames Morris 12282f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 12292f9092e1SDavid Woodhouse 1230057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1231057f6c01SJames Morris if (err) 1232057f6c01SJames Morris return ERR_PTR(err); 1233eead1911SChristoph Hellwig 1234b75b5086SAl Viro err = exec_permission(base->d_inode); 1235eead1911SChristoph Hellwig if (err) 1236eead1911SChristoph Hellwig return ERR_PTR(err); 123749705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1238057f6c01SJames Morris } 1239057f6c01SJames Morris 12402d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 12412d8f3038SAl Viro struct path *path) 12421da177e4SLinus Torvalds { 12432d8f3038SAl Viro struct nameidata nd; 12441da177e4SLinus Torvalds char *tmp = getname(name); 12451da177e4SLinus Torvalds int err = PTR_ERR(tmp); 12461da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 12472d8f3038SAl Viro 12482d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 12492d8f3038SAl Viro 12502d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 12511da177e4SLinus Torvalds putname(tmp); 12522d8f3038SAl Viro if (!err) 12532d8f3038SAl Viro *path = nd.path; 12541da177e4SLinus Torvalds } 12551da177e4SLinus Torvalds return err; 12561da177e4SLinus Torvalds } 12571da177e4SLinus Torvalds 12582ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 12592ad94ae6SAl Viro struct nameidata *nd, char **name) 12602ad94ae6SAl Viro { 12612ad94ae6SAl Viro char *s = getname(path); 12622ad94ae6SAl Viro int error; 12632ad94ae6SAl Viro 12642ad94ae6SAl Viro if (IS_ERR(s)) 12652ad94ae6SAl Viro return PTR_ERR(s); 12662ad94ae6SAl Viro 12672ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 12682ad94ae6SAl Viro if (error) 12692ad94ae6SAl Viro putname(s); 12702ad94ae6SAl Viro else 12712ad94ae6SAl Viro *name = s; 12722ad94ae6SAl Viro 12732ad94ae6SAl Viro return error; 12742ad94ae6SAl Viro } 12752ad94ae6SAl Viro 12761da177e4SLinus Torvalds /* 12771da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 12781da177e4SLinus Torvalds * minimal. 12791da177e4SLinus Torvalds */ 12801da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 12811da177e4SLinus Torvalds { 1282da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1283da9592edSDavid Howells 12841da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 12851da177e4SLinus Torvalds return 0; 1286da9592edSDavid Howells if (inode->i_uid == fsuid) 12871da177e4SLinus Torvalds return 0; 1288da9592edSDavid Howells if (dir->i_uid == fsuid) 12891da177e4SLinus Torvalds return 0; 12901da177e4SLinus Torvalds return !capable(CAP_FOWNER); 12911da177e4SLinus Torvalds } 12921da177e4SLinus Torvalds 12931da177e4SLinus Torvalds /* 12941da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 12951da177e4SLinus Torvalds * whether the type of victim is right. 12961da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 12971da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 12981da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 12991da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 13001da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 13011da177e4SLinus Torvalds * a. be owner of dir, or 13021da177e4SLinus Torvalds * b. be owner of victim, or 13031da177e4SLinus Torvalds * c. have CAP_FOWNER capability 13041da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 13051da177e4SLinus Torvalds * links pointing to it. 13061da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 13071da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 13081da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 13091da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 13101da177e4SLinus Torvalds * nfs_async_unlink(). 13111da177e4SLinus Torvalds */ 1312858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 13131da177e4SLinus Torvalds { 13141da177e4SLinus Torvalds int error; 13151da177e4SLinus Torvalds 13161da177e4SLinus Torvalds if (!victim->d_inode) 13171da177e4SLinus Torvalds return -ENOENT; 13181da177e4SLinus Torvalds 13191da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1320cccc6bbaSAl Viro audit_inode_child(victim, dir); 13211da177e4SLinus Torvalds 1322f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 13231da177e4SLinus Torvalds if (error) 13241da177e4SLinus Torvalds return error; 13251da177e4SLinus Torvalds if (IS_APPEND(dir)) 13261da177e4SLinus Torvalds return -EPERM; 13271da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1328f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 13291da177e4SLinus Torvalds return -EPERM; 13301da177e4SLinus Torvalds if (isdir) { 13311da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 13321da177e4SLinus Torvalds return -ENOTDIR; 13331da177e4SLinus Torvalds if (IS_ROOT(victim)) 13341da177e4SLinus Torvalds return -EBUSY; 13351da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 13361da177e4SLinus Torvalds return -EISDIR; 13371da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13381da177e4SLinus Torvalds return -ENOENT; 13391da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 13401da177e4SLinus Torvalds return -EBUSY; 13411da177e4SLinus Torvalds return 0; 13421da177e4SLinus Torvalds } 13431da177e4SLinus Torvalds 13441da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 13451da177e4SLinus Torvalds * dir. 13461da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 13471da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 13481da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 13491da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 13501da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 13511da177e4SLinus Torvalds */ 1352a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 13531da177e4SLinus Torvalds { 13541da177e4SLinus Torvalds if (child->d_inode) 13551da177e4SLinus Torvalds return -EEXIST; 13561da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 13571da177e4SLinus Torvalds return -ENOENT; 1358f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 13591da177e4SLinus Torvalds } 13601da177e4SLinus Torvalds 13611da177e4SLinus Torvalds /* 13621da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 13631da177e4SLinus Torvalds */ 13641da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 13651da177e4SLinus Torvalds { 13661da177e4SLinus Torvalds struct dentry *p; 13671da177e4SLinus Torvalds 13681da177e4SLinus Torvalds if (p1 == p2) { 1369f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 13701da177e4SLinus Torvalds return NULL; 13711da177e4SLinus Torvalds } 13721da177e4SLinus Torvalds 1373a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 13741da177e4SLinus Torvalds 1375e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1376e2761a11SOGAWA Hirofumi if (p) { 1377f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1378f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 13791da177e4SLinus Torvalds return p; 13801da177e4SLinus Torvalds } 13811da177e4SLinus Torvalds 1382e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1383e2761a11SOGAWA Hirofumi if (p) { 1384f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1385f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 13861da177e4SLinus Torvalds return p; 13871da177e4SLinus Torvalds } 13881da177e4SLinus Torvalds 1389f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1390f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 13911da177e4SLinus Torvalds return NULL; 13921da177e4SLinus Torvalds } 13931da177e4SLinus Torvalds 13941da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 13951da177e4SLinus Torvalds { 13961b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 13971da177e4SLinus Torvalds if (p1 != p2) { 13981b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1399a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 14001da177e4SLinus Torvalds } 14011da177e4SLinus Torvalds } 14021da177e4SLinus Torvalds 14031da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 14041da177e4SLinus Torvalds struct nameidata *nd) 14051da177e4SLinus Torvalds { 1406a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 14071da177e4SLinus Torvalds 14081da177e4SLinus Torvalds if (error) 14091da177e4SLinus Torvalds return error; 14101da177e4SLinus Torvalds 1411acfa4380SAl Viro if (!dir->i_op->create) 14121da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 14131da177e4SLinus Torvalds mode &= S_IALLUGO; 14141da177e4SLinus Torvalds mode |= S_IFREG; 14151da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 14161da177e4SLinus Torvalds if (error) 14171da177e4SLinus Torvalds return error; 14181da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1419a74574aaSStephen Smalley if (!error) 1420f38aa942SAmy Griffis fsnotify_create(dir, dentry); 14211da177e4SLinus Torvalds return error; 14221da177e4SLinus Torvalds } 14231da177e4SLinus Torvalds 14243fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 14251da177e4SLinus Torvalds { 14263fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 14271da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 14281da177e4SLinus Torvalds int error; 14291da177e4SLinus Torvalds 14301da177e4SLinus Torvalds if (!inode) 14311da177e4SLinus Torvalds return -ENOENT; 14321da177e4SLinus Torvalds 1433c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 1434c8fe8f30SChristoph Hellwig case S_IFLNK: 14351da177e4SLinus Torvalds return -ELOOP; 1436c8fe8f30SChristoph Hellwig case S_IFDIR: 1437c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 14381da177e4SLinus Torvalds return -EISDIR; 1439c8fe8f30SChristoph Hellwig break; 1440c8fe8f30SChristoph Hellwig case S_IFBLK: 1441c8fe8f30SChristoph Hellwig case S_IFCHR: 14423fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 14431da177e4SLinus Torvalds return -EACCES; 1444c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 1445c8fe8f30SChristoph Hellwig case S_IFIFO: 1446c8fe8f30SChristoph Hellwig case S_IFSOCK: 14471da177e4SLinus Torvalds flag &= ~O_TRUNC; 1448c8fe8f30SChristoph Hellwig break; 14494a3fd211SDave Hansen } 1450b41572e9SDave Hansen 14513fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 1452b41572e9SDave Hansen if (error) 1453b41572e9SDave Hansen return error; 14546146f0d5SMimi Zohar 14551da177e4SLinus Torvalds /* 14561da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 14571da177e4SLinus Torvalds */ 14581da177e4SLinus Torvalds if (IS_APPEND(inode)) { 14598737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 14607715b521SAl Viro return -EPERM; 14611da177e4SLinus Torvalds if (flag & O_TRUNC) 14627715b521SAl Viro return -EPERM; 14631da177e4SLinus Torvalds } 14641da177e4SLinus Torvalds 14651da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 14667715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 14677715b521SAl Viro return -EPERM; 14681da177e4SLinus Torvalds 14691da177e4SLinus Torvalds /* 14701da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 14711da177e4SLinus Torvalds */ 1472b65a9cfcSAl Viro return break_lease(inode, flag); 14737715b521SAl Viro } 14747715b521SAl Viro 14757715b521SAl Viro static int handle_truncate(struct path *path) 14767715b521SAl Viro { 14777715b521SAl Viro struct inode *inode = path->dentry->d_inode; 14787715b521SAl Viro int error = get_write_access(inode); 14791da177e4SLinus Torvalds if (error) 14807715b521SAl Viro return error; 14811da177e4SLinus Torvalds /* 14821da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 14831da177e4SLinus Torvalds */ 14841da177e4SLinus Torvalds error = locks_verify_locked(inode); 1485be6d3e56SKentaro Takeda if (!error) 14863fb64190SChristoph Hellwig error = security_path_truncate(path, 0, 1487be6d3e56SKentaro Takeda ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); 14881da177e4SLinus Torvalds if (!error) { 14897715b521SAl Viro error = do_truncate(path->dentry, 0, 1490d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 1491d139d7ffSMiklos Szeredi NULL); 14921da177e4SLinus Torvalds } 14931da177e4SLinus Torvalds put_write_access(inode); 1494acd0c935SMimi Zohar return error; 14951da177e4SLinus Torvalds } 14961da177e4SLinus Torvalds 1497d57999e1SDave Hansen /* 1498d57999e1SDave Hansen * Be careful about ever adding any more callers of this 1499d57999e1SDave Hansen * function. Its flags must be in the namei format, not 1500d57999e1SDave Hansen * what get passed to sys_open(). 1501d57999e1SDave Hansen */ 1502d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 15038737c930SAl Viro int open_flag, int mode) 1504aab520e2SDave Hansen { 1505aab520e2SDave Hansen int error; 15064ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 1507aab520e2SDave Hansen 1508aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 1509ce3b0f8dSAl Viro mode &= ~current_umask(); 1510be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 1511be6d3e56SKentaro Takeda if (error) 1512be6d3e56SKentaro Takeda goto out_unlock; 1513aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 1514be6d3e56SKentaro Takeda out_unlock: 1515aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 15164ac91378SJan Blunck dput(nd->path.dentry); 15174ac91378SJan Blunck nd->path.dentry = path->dentry; 1518aab520e2SDave Hansen if (error) 1519aab520e2SDave Hansen return error; 1520aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 15218737c930SAl Viro return may_open(&nd->path, 0, open_flag & ~O_TRUNC); 1522aab520e2SDave Hansen } 1523aab520e2SDave Hansen 15241da177e4SLinus Torvalds /* 1525d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 1526d57999e1SDave Hansen * 00 - read-only 1527d57999e1SDave Hansen * 01 - write-only 1528d57999e1SDave Hansen * 10 - read-write 1529d57999e1SDave Hansen * 11 - special 1530d57999e1SDave Hansen * it is changed into 1531d57999e1SDave Hansen * 00 - no permissions needed 1532d57999e1SDave Hansen * 01 - read-permission 1533d57999e1SDave Hansen * 10 - write-permission 1534d57999e1SDave Hansen * 11 - read-write 1535d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 1536d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 1537d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 1538d57999e1SDave Hansen * later). 1539d57999e1SDave Hansen * 1540d57999e1SDave Hansen */ 1541d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 1542d57999e1SDave Hansen { 1543d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 1544d57999e1SDave Hansen flag++; 1545d57999e1SDave Hansen return flag; 1546d57999e1SDave Hansen } 1547d57999e1SDave Hansen 15487715b521SAl Viro static int open_will_truncate(int flag, struct inode *inode) 15494a3fd211SDave Hansen { 1550d57999e1SDave Hansen /* 15514a3fd211SDave Hansen * We'll never write to the fs underlying 15524a3fd211SDave Hansen * a device file. 15534a3fd211SDave Hansen */ 15544a3fd211SDave Hansen if (special_file(inode->i_mode)) 15554a3fd211SDave Hansen return 0; 15564a3fd211SDave Hansen return (flag & O_TRUNC); 15574a3fd211SDave Hansen } 15584a3fd211SDave Hansen 1559648fa861SAl Viro static struct file *finish_open(struct nameidata *nd, 15609a66179eSAl Viro int open_flag, int acc_mode) 1561648fa861SAl Viro { 1562648fa861SAl Viro struct file *filp; 1563648fa861SAl Viro int will_truncate; 1564648fa861SAl Viro int error; 1565648fa861SAl Viro 15669a66179eSAl Viro will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode); 1567648fa861SAl Viro if (will_truncate) { 1568648fa861SAl Viro error = mnt_want_write(nd->path.mnt); 1569648fa861SAl Viro if (error) 1570648fa861SAl Viro goto exit; 1571648fa861SAl Viro } 1572648fa861SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 1573648fa861SAl Viro if (error) { 1574648fa861SAl Viro if (will_truncate) 1575648fa861SAl Viro mnt_drop_write(nd->path.mnt); 1576648fa861SAl Viro goto exit; 1577648fa861SAl Viro } 1578648fa861SAl Viro filp = nameidata_to_filp(nd); 1579648fa861SAl Viro if (!IS_ERR(filp)) { 1580648fa861SAl Viro error = ima_file_check(filp, acc_mode); 1581648fa861SAl Viro if (error) { 1582648fa861SAl Viro fput(filp); 1583648fa861SAl Viro filp = ERR_PTR(error); 1584648fa861SAl Viro } 1585648fa861SAl Viro } 1586648fa861SAl Viro if (!IS_ERR(filp)) { 1587648fa861SAl Viro if (will_truncate) { 1588648fa861SAl Viro error = handle_truncate(&nd->path); 1589648fa861SAl Viro if (error) { 1590648fa861SAl Viro fput(filp); 1591648fa861SAl Viro filp = ERR_PTR(error); 1592648fa861SAl Viro } 1593648fa861SAl Viro } 1594648fa861SAl Viro } 1595648fa861SAl Viro /* 1596648fa861SAl Viro * It is now safe to drop the mnt write 1597648fa861SAl Viro * because the filp has had a write taken 1598648fa861SAl Viro * on its behalf. 1599648fa861SAl Viro */ 1600648fa861SAl Viro if (will_truncate) 1601648fa861SAl Viro mnt_drop_write(nd->path.mnt); 1602648fa861SAl Viro return filp; 1603648fa861SAl Viro 1604648fa861SAl Viro exit: 1605648fa861SAl Viro if (!IS_ERR(nd->intent.open.file)) 1606648fa861SAl Viro release_open_intent(nd); 1607648fa861SAl Viro path_put(&nd->path); 1608648fa861SAl Viro return ERR_PTR(error); 1609648fa861SAl Viro } 1610648fa861SAl Viro 1611fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 16125b369df8SAl Viro int open_flag, int acc_mode, 16133e297b61SAl Viro int mode, const char *pathname) 1614fb1cc555SAl Viro { 1615a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 1616fb1cc555SAl Viro struct file *filp; 16171f36f774SAl Viro int error = -EISDIR; 1618fb1cc555SAl Viro 16191f36f774SAl Viro switch (nd->last_type) { 16201f36f774SAl Viro case LAST_DOTDOT: 16211f36f774SAl Viro follow_dotdot(nd); 16221f36f774SAl Viro dir = nd->path.dentry; 16231f36f774SAl Viro if (nd->path.mnt->mnt_sb->s_type->fs_flags & FS_REVAL_DOT) { 16241f36f774SAl Viro if (!dir->d_op->d_revalidate(dir, nd)) { 16251f36f774SAl Viro error = -ESTALE; 1626a2c36b45SAl Viro goto exit; 16271f36f774SAl Viro } 16281f36f774SAl Viro } 16291f36f774SAl Viro /* fallthrough */ 16301f36f774SAl Viro case LAST_DOT: 16311f36f774SAl Viro case LAST_ROOT: 16321f36f774SAl Viro if (open_flag & O_CREAT) 16331f36f774SAl Viro goto exit; 16341f36f774SAl Viro /* fallthrough */ 16351f36f774SAl Viro case LAST_BIND: 16361f36f774SAl Viro audit_inode(pathname, dir); 16371f36f774SAl Viro goto ok; 16381f36f774SAl Viro } 1639a2c36b45SAl Viro 16401f36f774SAl Viro /* trailing slashes? */ 16411f36f774SAl Viro if (nd->last.name[nd->last.len]) { 16421f36f774SAl Viro if (open_flag & O_CREAT) 16431f36f774SAl Viro goto exit; 1644002baeecSJan Kara nd->flags |= LOOKUP_DIRECTORY | LOOKUP_FOLLOW; 16451f36f774SAl Viro } 16461f36f774SAl Viro 16471f36f774SAl Viro /* just plain open? */ 16481f36f774SAl Viro if (!(open_flag & O_CREAT)) { 16491f36f774SAl Viro error = do_lookup(nd, &nd->last, path); 16501f36f774SAl Viro if (error) 16511f36f774SAl Viro goto exit; 16521f36f774SAl Viro error = -ENOENT; 16531f36f774SAl Viro if (!path->dentry->d_inode) 16541f36f774SAl Viro goto exit_dput; 16551f36f774SAl Viro if (path->dentry->d_inode->i_op->follow_link) 16561f36f774SAl Viro return NULL; 16571f36f774SAl Viro error = -ENOTDIR; 16583e297b61SAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 16593e297b61SAl Viro if (!path->dentry->d_inode->i_op->lookup) 16601f36f774SAl Viro goto exit_dput; 16613e297b61SAl Viro } 16621f36f774SAl Viro path_to_nameidata(path, nd); 16631f36f774SAl Viro audit_inode(pathname, nd->path.dentry); 16641f36f774SAl Viro goto ok; 16651f36f774SAl Viro } 16661f36f774SAl Viro 16671f36f774SAl Viro /* OK, it's O_CREAT */ 1668a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 1669a1e28038SAl Viro 1670a1e28038SAl Viro path->dentry = lookup_hash(nd); 1671a1e28038SAl Viro path->mnt = nd->path.mnt; 1672a1e28038SAl Viro 1673fb1cc555SAl Viro error = PTR_ERR(path->dentry); 1674fb1cc555SAl Viro if (IS_ERR(path->dentry)) { 1675fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 1676fb1cc555SAl Viro goto exit; 1677fb1cc555SAl Viro } 1678fb1cc555SAl Viro 1679fb1cc555SAl Viro if (IS_ERR(nd->intent.open.file)) { 1680fb1cc555SAl Viro error = PTR_ERR(nd->intent.open.file); 1681fb1cc555SAl Viro goto exit_mutex_unlock; 1682fb1cc555SAl Viro } 1683fb1cc555SAl Viro 1684fb1cc555SAl Viro /* Negative dentry, just create the file */ 1685fb1cc555SAl Viro if (!path->dentry->d_inode) { 1686fb1cc555SAl Viro /* 1687fb1cc555SAl Viro * This write is needed to ensure that a 1688fb1cc555SAl Viro * ro->rw transition does not occur between 1689fb1cc555SAl Viro * the time when the file is created and when 1690fb1cc555SAl Viro * a permanent write count is taken through 1691fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 1692fb1cc555SAl Viro */ 1693fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 1694fb1cc555SAl Viro if (error) 1695fb1cc555SAl Viro goto exit_mutex_unlock; 1696fb1cc555SAl Viro error = __open_namei_create(nd, path, open_flag, mode); 1697fb1cc555SAl Viro if (error) { 1698fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 1699fb1cc555SAl Viro goto exit; 1700fb1cc555SAl Viro } 1701fb1cc555SAl Viro filp = nameidata_to_filp(nd); 1702fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 1703fb1cc555SAl Viro if (!IS_ERR(filp)) { 1704fb1cc555SAl Viro error = ima_file_check(filp, acc_mode); 1705fb1cc555SAl Viro if (error) { 1706fb1cc555SAl Viro fput(filp); 1707fb1cc555SAl Viro filp = ERR_PTR(error); 1708fb1cc555SAl Viro } 1709fb1cc555SAl Viro } 1710fb1cc555SAl Viro return filp; 1711fb1cc555SAl Viro } 1712fb1cc555SAl Viro 1713fb1cc555SAl Viro /* 1714fb1cc555SAl Viro * It already exists. 1715fb1cc555SAl Viro */ 1716fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 1717fb1cc555SAl Viro audit_inode(pathname, path->dentry); 1718fb1cc555SAl Viro 1719fb1cc555SAl Viro error = -EEXIST; 17205b369df8SAl Viro if (open_flag & O_EXCL) 1721fb1cc555SAl Viro goto exit_dput; 1722fb1cc555SAl Viro 1723fb1cc555SAl Viro if (__follow_mount(path)) { 1724fb1cc555SAl Viro error = -ELOOP; 17255b369df8SAl Viro if (open_flag & O_NOFOLLOW) 1726fb1cc555SAl Viro goto exit_dput; 1727fb1cc555SAl Viro } 1728fb1cc555SAl Viro 1729fb1cc555SAl Viro error = -ENOENT; 1730fb1cc555SAl Viro if (!path->dentry->d_inode) 1731fb1cc555SAl Viro goto exit_dput; 17329e67f361SAl Viro 17339e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 1734fb1cc555SAl Viro return NULL; 1735fb1cc555SAl Viro 1736fb1cc555SAl Viro path_to_nameidata(path, nd); 1737fb1cc555SAl Viro error = -EISDIR; 1738fb1cc555SAl Viro if (S_ISDIR(path->dentry->d_inode->i_mode)) 1739fb1cc555SAl Viro goto exit; 174067ee3ad2SAl Viro ok: 17419a66179eSAl Viro filp = finish_open(nd, open_flag, acc_mode); 1742fb1cc555SAl Viro return filp; 1743fb1cc555SAl Viro 1744fb1cc555SAl Viro exit_mutex_unlock: 1745fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 1746fb1cc555SAl Viro exit_dput: 1747fb1cc555SAl Viro path_put_conditional(path, nd); 1748fb1cc555SAl Viro exit: 1749fb1cc555SAl Viro if (!IS_ERR(nd->intent.open.file)) 1750fb1cc555SAl Viro release_open_intent(nd); 1751fb1cc555SAl Viro path_put(&nd->path); 1752fb1cc555SAl Viro return ERR_PTR(error); 1753fb1cc555SAl Viro } 1754fb1cc555SAl Viro 17554a3fd211SDave Hansen /* 17564a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 17574a3fd211SDave Hansen * are not the same as in the local variable "flag". See 17584a3fd211SDave Hansen * open_to_namei_flags() for more details. 17591da177e4SLinus Torvalds */ 1760a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 17616e8341a1SAl Viro int open_flag, int mode, int acc_mode) 17621da177e4SLinus Torvalds { 17634a3fd211SDave Hansen struct file *filp; 1764a70e65dfSChristoph Hellwig struct nameidata nd; 17656e8341a1SAl Viro int error; 17669850c056SAl Viro struct path path; 17671da177e4SLinus Torvalds int count = 0; 1768d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 17699850c056SAl Viro int force_reval = 0; 17701f36f774SAl Viro 17711f36f774SAl Viro if (!(open_flag & O_CREAT)) 17721f36f774SAl Viro mode = 0; 17731da177e4SLinus Torvalds 17746b2f3d1fSChristoph Hellwig /* 17756b2f3d1fSChristoph Hellwig * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only 17766b2f3d1fSChristoph Hellwig * check for O_DSYNC if the need any syncing at all we enforce it's 17776b2f3d1fSChristoph Hellwig * always set instead of having to deal with possibly weird behaviour 17786b2f3d1fSChristoph Hellwig * for malicious applications setting only __O_SYNC. 17796b2f3d1fSChristoph Hellwig */ 17806b2f3d1fSChristoph Hellwig if (open_flag & __O_SYNC) 17816b2f3d1fSChristoph Hellwig open_flag |= O_DSYNC; 17826b2f3d1fSChristoph Hellwig 17836e8341a1SAl Viro if (!acc_mode) 17846d125529SAl Viro acc_mode = MAY_OPEN | ACC_MODE(open_flag); 17851da177e4SLinus Torvalds 1786834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 17874296e2cbSAl Viro if (open_flag & O_TRUNC) 1788834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 1789834f2a4aSTrond Myklebust 17901da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 17911da177e4SLinus Torvalds access from general write access. */ 17924296e2cbSAl Viro if (open_flag & O_APPEND) 17931da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 17941da177e4SLinus Torvalds 17951f36f774SAl Viro /* find the parent */ 17969850c056SAl Viro reval: 17979b4a9b14SAl Viro error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); 17981da177e4SLinus Torvalds if (error) 1799a70e65dfSChristoph Hellwig return ERR_PTR(error); 18009850c056SAl Viro if (force_reval) 18019850c056SAl Viro nd.flags |= LOOKUP_REVAL; 18023866248eSAl Viro 18033866248eSAl Viro current->total_link_count = 0; 18043866248eSAl Viro error = link_path_walk(pathname, &nd); 1805654f562cSJ. R. Okajima if (error) { 180610fa8e62SAl Viro filp = ERR_PTR(error); 180710fa8e62SAl Viro goto out; 1808654f562cSJ. R. Okajima } 18091f36f774SAl Viro if (unlikely(!audit_dummy_context()) && (open_flag & O_CREAT)) 18109b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 18111da177e4SLinus Torvalds 18121da177e4SLinus Torvalds /* 1813a2c36b45SAl Viro * We have the parent and last component. 18141da177e4SLinus Torvalds */ 18151da177e4SLinus Torvalds 18168737f3a1SAl Viro error = -ENFILE; 18178737f3a1SAl Viro filp = get_empty_filp(); 18188737f3a1SAl Viro if (filp == NULL) 18198737f3a1SAl Viro goto exit_parent; 18208737f3a1SAl Viro nd.intent.open.file = filp; 1821482928d5SAl Viro filp->f_flags = open_flag; 18228737f3a1SAl Viro nd.intent.open.flags = flag; 18238737f3a1SAl Viro nd.intent.open.create_mode = mode; 1824a70e65dfSChristoph Hellwig nd.flags &= ~LOOKUP_PARENT; 18251f36f774SAl Viro nd.flags |= LOOKUP_OPEN; 18261f36f774SAl Viro if (open_flag & O_CREAT) { 18271f36f774SAl Viro nd.flags |= LOOKUP_CREATE; 18284296e2cbSAl Viro if (open_flag & O_EXCL) 18293516586aSAl Viro nd.flags |= LOOKUP_EXCL; 18301f36f774SAl Viro } 18313e297b61SAl Viro if (open_flag & O_DIRECTORY) 18323e297b61SAl Viro nd.flags |= LOOKUP_DIRECTORY; 1833002baeecSJan Kara if (!(open_flag & O_NOFOLLOW)) 1834002baeecSJan Kara nd.flags |= LOOKUP_FOLLOW; 18353e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 1836806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 1837def4af30SAl Viro struct path holder; 18381f36f774SAl Viro struct inode *inode = path.dentry->d_inode; 1839def4af30SAl Viro void *cookie; 1840806b681cSAl Viro error = -ELOOP; 18411f36f774SAl Viro /* S_ISDIR part is a temporary automount kludge */ 1842002baeecSJan Kara if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(inode->i_mode)) 18431f36f774SAl Viro goto exit_dput; 18441f36f774SAl Viro if (count++ == 32) 1845806b681cSAl Viro goto exit_dput; 1846806b681cSAl Viro /* 1847806b681cSAl Viro * This is subtle. Instead of calling do_follow_link() we do 1848806b681cSAl Viro * the thing by hands. The reason is that this way we have zero 1849806b681cSAl Viro * link_count and path_walk() (called from ->follow_link) 1850806b681cSAl Viro * honoring LOOKUP_PARENT. After that we have the parent and 1851806b681cSAl Viro * last component, i.e. we are in the same situation as after 1852806b681cSAl Viro * the first path_walk(). Well, almost - if the last component 1853806b681cSAl Viro * is normal we get its copy stored in nd->last.name and we will 1854806b681cSAl Viro * have to putname() it when we are done. Procfs-like symlinks 1855806b681cSAl Viro * just set LAST_BIND. 1856806b681cSAl Viro */ 1857806b681cSAl Viro nd.flags |= LOOKUP_PARENT; 1858806b681cSAl Viro error = security_inode_follow_link(path.dentry, &nd); 1859806b681cSAl Viro if (error) 1860806b681cSAl Viro goto exit_dput; 1861def4af30SAl Viro error = __do_follow_link(&path, &nd, &cookie); 1862def4af30SAl Viro if (unlikely(error)) { 1863806b681cSAl Viro /* nd.path had been dropped */ 1864def4af30SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 1865def4af30SAl Viro inode->i_op->put_link(path.dentry, &nd, cookie); 1866def4af30SAl Viro path_put(&path); 1867a70e65dfSChristoph Hellwig release_open_intent(&nd); 186810fa8e62SAl Viro filp = ERR_PTR(error); 1869806b681cSAl Viro goto out; 1870806b681cSAl Viro } 1871def4af30SAl Viro holder = path; 1872806b681cSAl Viro nd.flags &= ~LOOKUP_PARENT; 18733e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 1874def4af30SAl Viro if (inode->i_op->put_link) 1875def4af30SAl Viro inode->i_op->put_link(holder.dentry, &nd, cookie); 1876def4af30SAl Viro path_put(&holder); 1877806b681cSAl Viro } 187810fa8e62SAl Viro out: 18792a737871SAl Viro if (nd.root.mnt) 18802a737871SAl Viro path_put(&nd.root); 188110fa8e62SAl Viro if (filp == ERR_PTR(-ESTALE) && !force_reval) { 188210fa8e62SAl Viro force_reval = 1; 188310fa8e62SAl Viro goto reval; 188410fa8e62SAl Viro } 188510fa8e62SAl Viro return filp; 18861da177e4SLinus Torvalds 1887806b681cSAl Viro exit_dput: 1888806b681cSAl Viro path_put_conditional(&path, &nd); 1889806b681cSAl Viro if (!IS_ERR(nd.intent.open.file)) 1890a70e65dfSChristoph Hellwig release_open_intent(&nd); 1891806b681cSAl Viro exit_parent: 1892806b681cSAl Viro path_put(&nd.path); 189310fa8e62SAl Viro filp = ERR_PTR(error); 189410fa8e62SAl Viro goto out; 1895de459215SKirill Korotaev } 18961da177e4SLinus Torvalds 18971da177e4SLinus Torvalds /** 1898a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 1899a70e65dfSChristoph Hellwig * 1900a70e65dfSChristoph Hellwig * @filename: path to open 1901a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 1902a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 1903a70e65dfSChristoph Hellwig * 1904a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 1905a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 1906a70e65dfSChristoph Hellwig * along, nothing to see here.. 1907a70e65dfSChristoph Hellwig */ 1908a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 1909a70e65dfSChristoph Hellwig { 19106e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 1911a70e65dfSChristoph Hellwig } 1912a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 1913a70e65dfSChristoph Hellwig 1914a70e65dfSChristoph Hellwig /** 19151da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 19161da177e4SLinus Torvalds * @nd: nameidata info 19171da177e4SLinus Torvalds * @is_dir: directory flag 19181da177e4SLinus Torvalds * 19191da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 19201da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 1921c663e5d8SChristoph Hellwig * 19224ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 19231da177e4SLinus Torvalds */ 19241da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 19251da177e4SLinus Torvalds { 1926c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 19271da177e4SLinus Torvalds 19284ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 1929c663e5d8SChristoph Hellwig /* 1930c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 1931c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 1932c663e5d8SChristoph Hellwig */ 19331da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 19341da177e4SLinus Torvalds goto fail; 19351da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 19363516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 1937a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 1938c663e5d8SChristoph Hellwig 1939c663e5d8SChristoph Hellwig /* 1940c663e5d8SChristoph Hellwig * Do the final lookup. 1941c663e5d8SChristoph Hellwig */ 194249705b77SChristoph Hellwig dentry = lookup_hash(nd); 19431da177e4SLinus Torvalds if (IS_ERR(dentry)) 19441da177e4SLinus Torvalds goto fail; 1945c663e5d8SChristoph Hellwig 1946e9baf6e5SAl Viro if (dentry->d_inode) 1947e9baf6e5SAl Viro goto eexist; 1948c663e5d8SChristoph Hellwig /* 1949c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 1950c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 1951c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 1952c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 1953c663e5d8SChristoph Hellwig */ 1954e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 19551da177e4SLinus Torvalds dput(dentry); 19561da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 1957e9baf6e5SAl Viro } 1958e9baf6e5SAl Viro return dentry; 1959e9baf6e5SAl Viro eexist: 1960e9baf6e5SAl Viro dput(dentry); 1961e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 19621da177e4SLinus Torvalds fail: 19631da177e4SLinus Torvalds return dentry; 19641da177e4SLinus Torvalds } 1965f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 19661da177e4SLinus Torvalds 19671da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 19681da177e4SLinus Torvalds { 1969a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19701da177e4SLinus Torvalds 19711da177e4SLinus Torvalds if (error) 19721da177e4SLinus Torvalds return error; 19731da177e4SLinus Torvalds 19741da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 19751da177e4SLinus Torvalds return -EPERM; 19761da177e4SLinus Torvalds 1977acfa4380SAl Viro if (!dir->i_op->mknod) 19781da177e4SLinus Torvalds return -EPERM; 19791da177e4SLinus Torvalds 198008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 198108ce5f16SSerge E. Hallyn if (error) 198208ce5f16SSerge E. Hallyn return error; 198308ce5f16SSerge E. Hallyn 19841da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 19851da177e4SLinus Torvalds if (error) 19861da177e4SLinus Torvalds return error; 19871da177e4SLinus Torvalds 19881da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 1989a74574aaSStephen Smalley if (!error) 1990f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19911da177e4SLinus Torvalds return error; 19921da177e4SLinus Torvalds } 19931da177e4SLinus Torvalds 1994463c3197SDave Hansen static int may_mknod(mode_t mode) 1995463c3197SDave Hansen { 1996463c3197SDave Hansen switch (mode & S_IFMT) { 1997463c3197SDave Hansen case S_IFREG: 1998463c3197SDave Hansen case S_IFCHR: 1999463c3197SDave Hansen case S_IFBLK: 2000463c3197SDave Hansen case S_IFIFO: 2001463c3197SDave Hansen case S_IFSOCK: 2002463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2003463c3197SDave Hansen return 0; 2004463c3197SDave Hansen case S_IFDIR: 2005463c3197SDave Hansen return -EPERM; 2006463c3197SDave Hansen default: 2007463c3197SDave Hansen return -EINVAL; 2008463c3197SDave Hansen } 2009463c3197SDave Hansen } 2010463c3197SDave Hansen 20112e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 20122e4d0924SHeiko Carstens unsigned, dev) 20131da177e4SLinus Torvalds { 20142ad94ae6SAl Viro int error; 20151da177e4SLinus Torvalds char *tmp; 20161da177e4SLinus Torvalds struct dentry *dentry; 20171da177e4SLinus Torvalds struct nameidata nd; 20181da177e4SLinus Torvalds 20191da177e4SLinus Torvalds if (S_ISDIR(mode)) 20201da177e4SLinus Torvalds return -EPERM; 20211da177e4SLinus Torvalds 20222ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 20231da177e4SLinus Torvalds if (error) 20242ad94ae6SAl Viro return error; 20252ad94ae6SAl Viro 20261da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2027463c3197SDave Hansen if (IS_ERR(dentry)) { 20281da177e4SLinus Torvalds error = PTR_ERR(dentry); 2029463c3197SDave Hansen goto out_unlock; 2030463c3197SDave Hansen } 20314ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2032ce3b0f8dSAl Viro mode &= ~current_umask(); 2033463c3197SDave Hansen error = may_mknod(mode); 2034463c3197SDave Hansen if (error) 2035463c3197SDave Hansen goto out_dput; 2036463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2037463c3197SDave Hansen if (error) 2038463c3197SDave Hansen goto out_dput; 2039be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2040be6d3e56SKentaro Takeda if (error) 2041be6d3e56SKentaro Takeda goto out_drop_write; 20421da177e4SLinus Torvalds switch (mode & S_IFMT) { 20431da177e4SLinus Torvalds case 0: case S_IFREG: 20444ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 20451da177e4SLinus Torvalds break; 20461da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 20474ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 20481da177e4SLinus Torvalds new_decode_dev(dev)); 20491da177e4SLinus Torvalds break; 20501da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 20514ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 20521da177e4SLinus Torvalds break; 20531da177e4SLinus Torvalds } 2054be6d3e56SKentaro Takeda out_drop_write: 2055463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2056463c3197SDave Hansen out_dput: 20571da177e4SLinus Torvalds dput(dentry); 2058463c3197SDave Hansen out_unlock: 20594ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 20601d957f9bSJan Blunck path_put(&nd.path); 20611da177e4SLinus Torvalds putname(tmp); 20621da177e4SLinus Torvalds 20631da177e4SLinus Torvalds return error; 20641da177e4SLinus Torvalds } 20651da177e4SLinus Torvalds 20663480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 20675590ff0dSUlrich Drepper { 20685590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 20695590ff0dSUlrich Drepper } 20705590ff0dSUlrich Drepper 20711da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 20721da177e4SLinus Torvalds { 2073a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20741da177e4SLinus Torvalds 20751da177e4SLinus Torvalds if (error) 20761da177e4SLinus Torvalds return error; 20771da177e4SLinus Torvalds 2078acfa4380SAl Viro if (!dir->i_op->mkdir) 20791da177e4SLinus Torvalds return -EPERM; 20801da177e4SLinus Torvalds 20811da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 20821da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 20831da177e4SLinus Torvalds if (error) 20841da177e4SLinus Torvalds return error; 20851da177e4SLinus Torvalds 20861da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2087a74574aaSStephen Smalley if (!error) 2088f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 20891da177e4SLinus Torvalds return error; 20901da177e4SLinus Torvalds } 20911da177e4SLinus Torvalds 20922e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 20931da177e4SLinus Torvalds { 20941da177e4SLinus Torvalds int error = 0; 20951da177e4SLinus Torvalds char * tmp; 20966902d925SDave Hansen struct dentry *dentry; 20976902d925SDave Hansen struct nameidata nd; 20981da177e4SLinus Torvalds 20992ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 21002ad94ae6SAl Viro if (error) 21016902d925SDave Hansen goto out_err; 21021da177e4SLinus Torvalds 21031da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 21041da177e4SLinus Torvalds error = PTR_ERR(dentry); 21056902d925SDave Hansen if (IS_ERR(dentry)) 21066902d925SDave Hansen goto out_unlock; 21076902d925SDave Hansen 21084ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2109ce3b0f8dSAl Viro mode &= ~current_umask(); 2110463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2111463c3197SDave Hansen if (error) 2112463c3197SDave Hansen goto out_dput; 2113be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2114be6d3e56SKentaro Takeda if (error) 2115be6d3e56SKentaro Takeda goto out_drop_write; 21164ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2117be6d3e56SKentaro Takeda out_drop_write: 2118463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2119463c3197SDave Hansen out_dput: 21201da177e4SLinus Torvalds dput(dentry); 21216902d925SDave Hansen out_unlock: 21224ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 21231d957f9bSJan Blunck path_put(&nd.path); 21241da177e4SLinus Torvalds putname(tmp); 21256902d925SDave Hansen out_err: 21261da177e4SLinus Torvalds return error; 21271da177e4SLinus Torvalds } 21281da177e4SLinus Torvalds 21293cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 21305590ff0dSUlrich Drepper { 21315590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 21325590ff0dSUlrich Drepper } 21335590ff0dSUlrich Drepper 21341da177e4SLinus Torvalds /* 21351da177e4SLinus Torvalds * We try to drop the dentry early: we should have 21361da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 21371da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 21381da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 21391da177e4SLinus Torvalds * 21401da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 21411da177e4SLinus Torvalds * do a 21421da177e4SLinus Torvalds * 21431da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 21441da177e4SLinus Torvalds * return -EBUSY; 21451da177e4SLinus Torvalds * 21461da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 21471da177e4SLinus Torvalds * that is still in use by something else.. 21481da177e4SLinus Torvalds */ 21491da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 21501da177e4SLinus Torvalds { 21511da177e4SLinus Torvalds dget(dentry); 21521da177e4SLinus Torvalds shrink_dcache_parent(dentry); 21531da177e4SLinus Torvalds spin_lock(&dcache_lock); 21541da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 21551da177e4SLinus Torvalds if (atomic_read(&dentry->d_count) == 2) 21561da177e4SLinus Torvalds __d_drop(dentry); 21571da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 21581da177e4SLinus Torvalds spin_unlock(&dcache_lock); 21591da177e4SLinus Torvalds } 21601da177e4SLinus Torvalds 21611da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 21621da177e4SLinus Torvalds { 21631da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 21641da177e4SLinus Torvalds 21651da177e4SLinus Torvalds if (error) 21661da177e4SLinus Torvalds return error; 21671da177e4SLinus Torvalds 2168acfa4380SAl Viro if (!dir->i_op->rmdir) 21691da177e4SLinus Torvalds return -EPERM; 21701da177e4SLinus Torvalds 21711b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 21721da177e4SLinus Torvalds dentry_unhash(dentry); 21731da177e4SLinus Torvalds if (d_mountpoint(dentry)) 21741da177e4SLinus Torvalds error = -EBUSY; 21751da177e4SLinus Torvalds else { 21761da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 21771da177e4SLinus Torvalds if (!error) { 21781da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2179d83c49f3SAl Viro if (!error) { 21801da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2181d83c49f3SAl Viro dont_mount(dentry); 2182d83c49f3SAl Viro } 21831da177e4SLinus Torvalds } 21841da177e4SLinus Torvalds } 21851b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 21861da177e4SLinus Torvalds if (!error) { 21871da177e4SLinus Torvalds d_delete(dentry); 21881da177e4SLinus Torvalds } 21891da177e4SLinus Torvalds dput(dentry); 21901da177e4SLinus Torvalds 21911da177e4SLinus Torvalds return error; 21921da177e4SLinus Torvalds } 21931da177e4SLinus Torvalds 21945590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 21951da177e4SLinus Torvalds { 21961da177e4SLinus Torvalds int error = 0; 21971da177e4SLinus Torvalds char * name; 21981da177e4SLinus Torvalds struct dentry *dentry; 21991da177e4SLinus Torvalds struct nameidata nd; 22001da177e4SLinus Torvalds 22012ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22021da177e4SLinus Torvalds if (error) 22032ad94ae6SAl Viro return error; 22041da177e4SLinus Torvalds 22051da177e4SLinus Torvalds switch(nd.last_type) { 22061da177e4SLinus Torvalds case LAST_DOTDOT: 22071da177e4SLinus Torvalds error = -ENOTEMPTY; 22081da177e4SLinus Torvalds goto exit1; 22091da177e4SLinus Torvalds case LAST_DOT: 22101da177e4SLinus Torvalds error = -EINVAL; 22111da177e4SLinus Torvalds goto exit1; 22121da177e4SLinus Torvalds case LAST_ROOT: 22131da177e4SLinus Torvalds error = -EBUSY; 22141da177e4SLinus Torvalds goto exit1; 22151da177e4SLinus Torvalds } 22160612d9fbSOGAWA Hirofumi 22170612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 22180612d9fbSOGAWA Hirofumi 22194ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 222049705b77SChristoph Hellwig dentry = lookup_hash(&nd); 22211da177e4SLinus Torvalds error = PTR_ERR(dentry); 22226902d925SDave Hansen if (IS_ERR(dentry)) 22236902d925SDave Hansen goto exit2; 22240622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 22250622753bSDave Hansen if (error) 22260622753bSDave Hansen goto exit3; 2227be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2228be6d3e56SKentaro Takeda if (error) 2229be6d3e56SKentaro Takeda goto exit4; 22304ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2231be6d3e56SKentaro Takeda exit4: 22320622753bSDave Hansen mnt_drop_write(nd.path.mnt); 22330622753bSDave Hansen exit3: 22341da177e4SLinus Torvalds dput(dentry); 22356902d925SDave Hansen exit2: 22364ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 22371da177e4SLinus Torvalds exit1: 22381d957f9bSJan Blunck path_put(&nd.path); 22391da177e4SLinus Torvalds putname(name); 22401da177e4SLinus Torvalds return error; 22411da177e4SLinus Torvalds } 22421da177e4SLinus Torvalds 22433cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 22445590ff0dSUlrich Drepper { 22455590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 22465590ff0dSUlrich Drepper } 22475590ff0dSUlrich Drepper 22481da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 22491da177e4SLinus Torvalds { 22501da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 22511da177e4SLinus Torvalds 22521da177e4SLinus Torvalds if (error) 22531da177e4SLinus Torvalds return error; 22541da177e4SLinus Torvalds 2255acfa4380SAl Viro if (!dir->i_op->unlink) 22561da177e4SLinus Torvalds return -EPERM; 22571da177e4SLinus Torvalds 22581b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 22591da177e4SLinus Torvalds if (d_mountpoint(dentry)) 22601da177e4SLinus Torvalds error = -EBUSY; 22611da177e4SLinus Torvalds else { 22621da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2263bec1052eSAl Viro if (!error) { 22641da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2265bec1052eSAl Viro if (!error) 2266d83c49f3SAl Viro dont_mount(dentry); 2267bec1052eSAl Viro } 22681da177e4SLinus Torvalds } 22691b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 22701da177e4SLinus Torvalds 22711da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 22721da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2273ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 22741da177e4SLinus Torvalds d_delete(dentry); 22751da177e4SLinus Torvalds } 22760eeca283SRobert Love 22771da177e4SLinus Torvalds return error; 22781da177e4SLinus Torvalds } 22791da177e4SLinus Torvalds 22801da177e4SLinus Torvalds /* 22811da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 22821b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 22831da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 22841da177e4SLinus Torvalds * while waiting on the I/O. 22851da177e4SLinus Torvalds */ 22865590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 22871da177e4SLinus Torvalds { 22882ad94ae6SAl Viro int error; 22891da177e4SLinus Torvalds char *name; 22901da177e4SLinus Torvalds struct dentry *dentry; 22911da177e4SLinus Torvalds struct nameidata nd; 22921da177e4SLinus Torvalds struct inode *inode = NULL; 22931da177e4SLinus Torvalds 22942ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 22951da177e4SLinus Torvalds if (error) 22962ad94ae6SAl Viro return error; 22972ad94ae6SAl Viro 22981da177e4SLinus Torvalds error = -EISDIR; 22991da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 23001da177e4SLinus Torvalds goto exit1; 23010612d9fbSOGAWA Hirofumi 23020612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 23030612d9fbSOGAWA Hirofumi 23044ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 230549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 23061da177e4SLinus Torvalds error = PTR_ERR(dentry); 23071da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 23081da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 23091da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 23101da177e4SLinus Torvalds goto slashes; 23111da177e4SLinus Torvalds inode = dentry->d_inode; 23121da177e4SLinus Torvalds if (inode) 23131da177e4SLinus Torvalds atomic_inc(&inode->i_count); 23140622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 23150622753bSDave Hansen if (error) 23160622753bSDave Hansen goto exit2; 2317be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2318be6d3e56SKentaro Takeda if (error) 2319be6d3e56SKentaro Takeda goto exit3; 23204ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2321be6d3e56SKentaro Takeda exit3: 23220622753bSDave Hansen mnt_drop_write(nd.path.mnt); 23231da177e4SLinus Torvalds exit2: 23241da177e4SLinus Torvalds dput(dentry); 23251da177e4SLinus Torvalds } 23264ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 23271da177e4SLinus Torvalds if (inode) 23281da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 23291da177e4SLinus Torvalds exit1: 23301d957f9bSJan Blunck path_put(&nd.path); 23311da177e4SLinus Torvalds putname(name); 23321da177e4SLinus Torvalds return error; 23331da177e4SLinus Torvalds 23341da177e4SLinus Torvalds slashes: 23351da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 23361da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 23371da177e4SLinus Torvalds goto exit2; 23381da177e4SLinus Torvalds } 23391da177e4SLinus Torvalds 23402e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 23415590ff0dSUlrich Drepper { 23425590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 23435590ff0dSUlrich Drepper return -EINVAL; 23445590ff0dSUlrich Drepper 23455590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 23465590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 23475590ff0dSUlrich Drepper 23485590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 23495590ff0dSUlrich Drepper } 23505590ff0dSUlrich Drepper 23513480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 23525590ff0dSUlrich Drepper { 23535590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 23545590ff0dSUlrich Drepper } 23555590ff0dSUlrich Drepper 2356db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 23571da177e4SLinus Torvalds { 2358a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 23591da177e4SLinus Torvalds 23601da177e4SLinus Torvalds if (error) 23611da177e4SLinus Torvalds return error; 23621da177e4SLinus Torvalds 2363acfa4380SAl Viro if (!dir->i_op->symlink) 23641da177e4SLinus Torvalds return -EPERM; 23651da177e4SLinus Torvalds 23661da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 23671da177e4SLinus Torvalds if (error) 23681da177e4SLinus Torvalds return error; 23691da177e4SLinus Torvalds 23701da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2371a74574aaSStephen Smalley if (!error) 2372f38aa942SAmy Griffis fsnotify_create(dir, dentry); 23731da177e4SLinus Torvalds return error; 23741da177e4SLinus Torvalds } 23751da177e4SLinus Torvalds 23762e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 23772e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 23781da177e4SLinus Torvalds { 23792ad94ae6SAl Viro int error; 23801da177e4SLinus Torvalds char *from; 23811da177e4SLinus Torvalds char *to; 23826902d925SDave Hansen struct dentry *dentry; 23836902d925SDave Hansen struct nameidata nd; 23841da177e4SLinus Torvalds 23851da177e4SLinus Torvalds from = getname(oldname); 23861da177e4SLinus Torvalds if (IS_ERR(from)) 23871da177e4SLinus Torvalds return PTR_ERR(from); 23882ad94ae6SAl Viro 23892ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 23902ad94ae6SAl Viro if (error) 23916902d925SDave Hansen goto out_putname; 23921da177e4SLinus Torvalds 23931da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 23941da177e4SLinus Torvalds error = PTR_ERR(dentry); 23956902d925SDave Hansen if (IS_ERR(dentry)) 23966902d925SDave Hansen goto out_unlock; 23976902d925SDave Hansen 239875c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 239975c3f29dSDave Hansen if (error) 240075c3f29dSDave Hansen goto out_dput; 2401be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 2402be6d3e56SKentaro Takeda if (error) 2403be6d3e56SKentaro Takeda goto out_drop_write; 2404db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 2405be6d3e56SKentaro Takeda out_drop_write: 240675c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 240775c3f29dSDave Hansen out_dput: 24081da177e4SLinus Torvalds dput(dentry); 24096902d925SDave Hansen out_unlock: 24104ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 24111d957f9bSJan Blunck path_put(&nd.path); 24121da177e4SLinus Torvalds putname(to); 24136902d925SDave Hansen out_putname: 24141da177e4SLinus Torvalds putname(from); 24151da177e4SLinus Torvalds return error; 24161da177e4SLinus Torvalds } 24171da177e4SLinus Torvalds 24183480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 24195590ff0dSUlrich Drepper { 24205590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 24215590ff0dSUlrich Drepper } 24225590ff0dSUlrich Drepper 24231da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 24241da177e4SLinus Torvalds { 24251da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 24261da177e4SLinus Torvalds int error; 24271da177e4SLinus Torvalds 24281da177e4SLinus Torvalds if (!inode) 24291da177e4SLinus Torvalds return -ENOENT; 24301da177e4SLinus Torvalds 2431a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 24321da177e4SLinus Torvalds if (error) 24331da177e4SLinus Torvalds return error; 24341da177e4SLinus Torvalds 24351da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 24361da177e4SLinus Torvalds return -EXDEV; 24371da177e4SLinus Torvalds 24381da177e4SLinus Torvalds /* 24391da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 24401da177e4SLinus Torvalds */ 24411da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 24421da177e4SLinus Torvalds return -EPERM; 2443acfa4380SAl Viro if (!dir->i_op->link) 24441da177e4SLinus Torvalds return -EPERM; 24457e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 24461da177e4SLinus Torvalds return -EPERM; 24471da177e4SLinus Torvalds 24481da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 24491da177e4SLinus Torvalds if (error) 24501da177e4SLinus Torvalds return error; 24511da177e4SLinus Torvalds 24527e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 24531da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 24547e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2455e31e14ecSStephen Smalley if (!error) 24567e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 24571da177e4SLinus Torvalds return error; 24581da177e4SLinus Torvalds } 24591da177e4SLinus Torvalds 24601da177e4SLinus Torvalds /* 24611da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 24621da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 24631da177e4SLinus Torvalds * newname. --KAB 24641da177e4SLinus Torvalds * 24651da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 24661da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 24671da177e4SLinus Torvalds * and other special files. --ADM 24681da177e4SLinus Torvalds */ 24692e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 24702e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 24711da177e4SLinus Torvalds { 24721da177e4SLinus Torvalds struct dentry *new_dentry; 24732d8f3038SAl Viro struct nameidata nd; 24742d8f3038SAl Viro struct path old_path; 24751da177e4SLinus Torvalds int error; 24761da177e4SLinus Torvalds char *to; 24771da177e4SLinus Torvalds 247845c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 2479c04030e1SUlrich Drepper return -EINVAL; 2480c04030e1SUlrich Drepper 24812d8f3038SAl Viro error = user_path_at(olddfd, oldname, 248245c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 24832d8f3038SAl Viro &old_path); 24841da177e4SLinus Torvalds if (error) 24852ad94ae6SAl Viro return error; 24862ad94ae6SAl Viro 24872ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 24881da177e4SLinus Torvalds if (error) 24891da177e4SLinus Torvalds goto out; 24901da177e4SLinus Torvalds error = -EXDEV; 24912d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 24921da177e4SLinus Torvalds goto out_release; 24931da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 24941da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 24956902d925SDave Hansen if (IS_ERR(new_dentry)) 24966902d925SDave Hansen goto out_unlock; 249775c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 249875c3f29dSDave Hansen if (error) 249975c3f29dSDave Hansen goto out_dput; 2500be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 2501be6d3e56SKentaro Takeda if (error) 2502be6d3e56SKentaro Takeda goto out_drop_write; 25032d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 2504be6d3e56SKentaro Takeda out_drop_write: 250575c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 250675c3f29dSDave Hansen out_dput: 25071da177e4SLinus Torvalds dput(new_dentry); 25086902d925SDave Hansen out_unlock: 25094ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 25101da177e4SLinus Torvalds out_release: 25111d957f9bSJan Blunck path_put(&nd.path); 25122ad94ae6SAl Viro putname(to); 25131da177e4SLinus Torvalds out: 25142d8f3038SAl Viro path_put(&old_path); 25151da177e4SLinus Torvalds 25161da177e4SLinus Torvalds return error; 25171da177e4SLinus Torvalds } 25181da177e4SLinus Torvalds 25193480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 25205590ff0dSUlrich Drepper { 2521c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 25225590ff0dSUlrich Drepper } 25235590ff0dSUlrich Drepper 25241da177e4SLinus Torvalds /* 25251da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 25261da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 25271da177e4SLinus Torvalds * Problems: 25281da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 25291da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 25301da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2531a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 25321da177e4SLinus Torvalds * story. 25331da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 25341b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 25351da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 25361da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2537a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 25381da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 25391da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 25401da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2541a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 25421da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 25431da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 25441da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 25451da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 25461da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 25471da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 25481da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 25491da177e4SLinus Torvalds * trick as in rmdir(). 25501da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 25511b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 25521da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 2553c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 25541da177e4SLinus Torvalds * locking]. 25551da177e4SLinus Torvalds */ 255675c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 25571da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 25581da177e4SLinus Torvalds { 25591da177e4SLinus Torvalds int error = 0; 25601da177e4SLinus Torvalds struct inode *target; 25611da177e4SLinus Torvalds 25621da177e4SLinus Torvalds /* 25631da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 25641da177e4SLinus Torvalds * we'll need to flip '..'. 25651da177e4SLinus Torvalds */ 25661da177e4SLinus Torvalds if (new_dir != old_dir) { 2567f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 25681da177e4SLinus Torvalds if (error) 25691da177e4SLinus Torvalds return error; 25701da177e4SLinus Torvalds } 25711da177e4SLinus Torvalds 25721da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 25731da177e4SLinus Torvalds if (error) 25741da177e4SLinus Torvalds return error; 25751da177e4SLinus Torvalds 25761da177e4SLinus Torvalds target = new_dentry->d_inode; 2577d83c49f3SAl Viro if (target) 25781b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 25791da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 25801da177e4SLinus Torvalds error = -EBUSY; 2581d83c49f3SAl Viro else { 2582d83c49f3SAl Viro if (target) 2583d83c49f3SAl Viro dentry_unhash(new_dentry); 25841da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 2585d83c49f3SAl Viro } 25861da177e4SLinus Torvalds if (target) { 2587d83c49f3SAl Viro if (!error) { 25881da177e4SLinus Torvalds target->i_flags |= S_DEAD; 2589d83c49f3SAl Viro dont_mount(new_dentry); 2590d83c49f3SAl Viro } 25911b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 25921da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 25931da177e4SLinus Torvalds d_rehash(new_dentry); 25941da177e4SLinus Torvalds dput(new_dentry); 25951da177e4SLinus Torvalds } 2596e31e14ecSStephen Smalley if (!error) 2597349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 25981da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 25991da177e4SLinus Torvalds return error; 26001da177e4SLinus Torvalds } 26011da177e4SLinus Torvalds 260275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 26031da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26041da177e4SLinus Torvalds { 26051da177e4SLinus Torvalds struct inode *target; 26061da177e4SLinus Torvalds int error; 26071da177e4SLinus Torvalds 26081da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 26091da177e4SLinus Torvalds if (error) 26101da177e4SLinus Torvalds return error; 26111da177e4SLinus Torvalds 26121da177e4SLinus Torvalds dget(new_dentry); 26131da177e4SLinus Torvalds target = new_dentry->d_inode; 26141da177e4SLinus Torvalds if (target) 26151b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 26161da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 26171da177e4SLinus Torvalds error = -EBUSY; 26181da177e4SLinus Torvalds else 26191da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 26201da177e4SLinus Torvalds if (!error) { 2621bec1052eSAl Viro if (target) 2622d83c49f3SAl Viro dont_mount(new_dentry); 2623349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 26241da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 26251da177e4SLinus Torvalds } 26261da177e4SLinus Torvalds if (target) 26271b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 26281da177e4SLinus Torvalds dput(new_dentry); 26291da177e4SLinus Torvalds return error; 26301da177e4SLinus Torvalds } 26311da177e4SLinus Torvalds 26321da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 26331da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 26341da177e4SLinus Torvalds { 26351da177e4SLinus Torvalds int error; 26361da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 26370eeca283SRobert Love const char *old_name; 26381da177e4SLinus Torvalds 26391da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 26401da177e4SLinus Torvalds return 0; 26411da177e4SLinus Torvalds 26421da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 26431da177e4SLinus Torvalds if (error) 26441da177e4SLinus Torvalds return error; 26451da177e4SLinus Torvalds 26461da177e4SLinus Torvalds if (!new_dentry->d_inode) 2647a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 26481da177e4SLinus Torvalds else 26491da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 26501da177e4SLinus Torvalds if (error) 26511da177e4SLinus Torvalds return error; 26521da177e4SLinus Torvalds 2653acfa4380SAl Viro if (!old_dir->i_op->rename) 26541da177e4SLinus Torvalds return -EPERM; 26551da177e4SLinus Torvalds 26560eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 26570eeca283SRobert Love 26581da177e4SLinus Torvalds if (is_dir) 26591da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 26601da177e4SLinus Torvalds else 26611da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 2662123df294SAl Viro if (!error) 2663123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 26645a190ae6SAl Viro new_dentry->d_inode, old_dentry); 26650eeca283SRobert Love fsnotify_oldname_free(old_name); 26660eeca283SRobert Love 26671da177e4SLinus Torvalds return error; 26681da177e4SLinus Torvalds } 26691da177e4SLinus Torvalds 26702e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 26712e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 26721da177e4SLinus Torvalds { 26731da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 26741da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 26751da177e4SLinus Torvalds struct dentry *trap; 26761da177e4SLinus Torvalds struct nameidata oldnd, newnd; 26772ad94ae6SAl Viro char *from; 26782ad94ae6SAl Viro char *to; 26792ad94ae6SAl Viro int error; 26801da177e4SLinus Torvalds 26812ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 26821da177e4SLinus Torvalds if (error) 26831da177e4SLinus Torvalds goto exit; 26841da177e4SLinus Torvalds 26852ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 26861da177e4SLinus Torvalds if (error) 26871da177e4SLinus Torvalds goto exit1; 26881da177e4SLinus Torvalds 26891da177e4SLinus Torvalds error = -EXDEV; 26904ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 26911da177e4SLinus Torvalds goto exit2; 26921da177e4SLinus Torvalds 26934ac91378SJan Blunck old_dir = oldnd.path.dentry; 26941da177e4SLinus Torvalds error = -EBUSY; 26951da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 26961da177e4SLinus Torvalds goto exit2; 26971da177e4SLinus Torvalds 26984ac91378SJan Blunck new_dir = newnd.path.dentry; 26991da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 27001da177e4SLinus Torvalds goto exit2; 27011da177e4SLinus Torvalds 27020612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 27030612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 27044e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 27050612d9fbSOGAWA Hirofumi 27061da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 27071da177e4SLinus Torvalds 270849705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 27091da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 27101da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 27111da177e4SLinus Torvalds goto exit3; 27121da177e4SLinus Torvalds /* source must exist */ 27131da177e4SLinus Torvalds error = -ENOENT; 27141da177e4SLinus Torvalds if (!old_dentry->d_inode) 27151da177e4SLinus Torvalds goto exit4; 27161da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 27171da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 27181da177e4SLinus Torvalds error = -ENOTDIR; 27191da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 27201da177e4SLinus Torvalds goto exit4; 27211da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 27221da177e4SLinus Torvalds goto exit4; 27231da177e4SLinus Torvalds } 27241da177e4SLinus Torvalds /* source should not be ancestor of target */ 27251da177e4SLinus Torvalds error = -EINVAL; 27261da177e4SLinus Torvalds if (old_dentry == trap) 27271da177e4SLinus Torvalds goto exit4; 272849705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 27291da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 27301da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 27311da177e4SLinus Torvalds goto exit4; 27321da177e4SLinus Torvalds /* target should not be an ancestor of source */ 27331da177e4SLinus Torvalds error = -ENOTEMPTY; 27341da177e4SLinus Torvalds if (new_dentry == trap) 27351da177e4SLinus Torvalds goto exit5; 27361da177e4SLinus Torvalds 27379079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 27389079b1ebSDave Hansen if (error) 27399079b1ebSDave Hansen goto exit5; 2740be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 2741be6d3e56SKentaro Takeda &newnd.path, new_dentry); 2742be6d3e56SKentaro Takeda if (error) 2743be6d3e56SKentaro Takeda goto exit6; 27441da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 27451da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 2746be6d3e56SKentaro Takeda exit6: 27479079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 27481da177e4SLinus Torvalds exit5: 27491da177e4SLinus Torvalds dput(new_dentry); 27501da177e4SLinus Torvalds exit4: 27511da177e4SLinus Torvalds dput(old_dentry); 27521da177e4SLinus Torvalds exit3: 27531da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 27541da177e4SLinus Torvalds exit2: 27551d957f9bSJan Blunck path_put(&newnd.path); 27562ad94ae6SAl Viro putname(to); 27571da177e4SLinus Torvalds exit1: 27581d957f9bSJan Blunck path_put(&oldnd.path); 27591da177e4SLinus Torvalds putname(from); 27602ad94ae6SAl Viro exit: 27611da177e4SLinus Torvalds return error; 27621da177e4SLinus Torvalds } 27631da177e4SLinus Torvalds 2764a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 27655590ff0dSUlrich Drepper { 27665590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 27675590ff0dSUlrich Drepper } 27685590ff0dSUlrich Drepper 27691da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 27701da177e4SLinus Torvalds { 27711da177e4SLinus Torvalds int len; 27721da177e4SLinus Torvalds 27731da177e4SLinus Torvalds len = PTR_ERR(link); 27741da177e4SLinus Torvalds if (IS_ERR(link)) 27751da177e4SLinus Torvalds goto out; 27761da177e4SLinus Torvalds 27771da177e4SLinus Torvalds len = strlen(link); 27781da177e4SLinus Torvalds if (len > (unsigned) buflen) 27791da177e4SLinus Torvalds len = buflen; 27801da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 27811da177e4SLinus Torvalds len = -EFAULT; 27821da177e4SLinus Torvalds out: 27831da177e4SLinus Torvalds return len; 27841da177e4SLinus Torvalds } 27851da177e4SLinus Torvalds 27861da177e4SLinus Torvalds /* 27871da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 27881da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 27891da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 27901da177e4SLinus Torvalds */ 27911da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 27921da177e4SLinus Torvalds { 27931da177e4SLinus Torvalds struct nameidata nd; 2794cc314eefSLinus Torvalds void *cookie; 2795694a1764SMarcin Slusarz int res; 2796cc314eefSLinus Torvalds 27971da177e4SLinus Torvalds nd.depth = 0; 2798cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 2799694a1764SMarcin Slusarz if (IS_ERR(cookie)) 2800694a1764SMarcin Slusarz return PTR_ERR(cookie); 2801694a1764SMarcin Slusarz 2802694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 28031da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 2804cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 2805694a1764SMarcin Slusarz return res; 28061da177e4SLinus Torvalds } 28071da177e4SLinus Torvalds 28081da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 28091da177e4SLinus Torvalds { 28101da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 28111da177e4SLinus Torvalds } 28121da177e4SLinus Torvalds 28131da177e4SLinus Torvalds /* get the link contents into pagecache */ 28141da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 28151da177e4SLinus Torvalds { 2816ebd09abbSDuane Griffin char *kaddr; 28171da177e4SLinus Torvalds struct page *page; 28181da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 2819090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 28201da177e4SLinus Torvalds if (IS_ERR(page)) 28216fe6900eSNick Piggin return (char*)page; 28221da177e4SLinus Torvalds *ppage = page; 2823ebd09abbSDuane Griffin kaddr = kmap(page); 2824ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 2825ebd09abbSDuane Griffin return kaddr; 28261da177e4SLinus Torvalds } 28271da177e4SLinus Torvalds 28281da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 28291da177e4SLinus Torvalds { 28301da177e4SLinus Torvalds struct page *page = NULL; 28311da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 28321da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 28331da177e4SLinus Torvalds if (page) { 28341da177e4SLinus Torvalds kunmap(page); 28351da177e4SLinus Torvalds page_cache_release(page); 28361da177e4SLinus Torvalds } 28371da177e4SLinus Torvalds return res; 28381da177e4SLinus Torvalds } 28391da177e4SLinus Torvalds 2840cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 28411da177e4SLinus Torvalds { 2842cc314eefSLinus Torvalds struct page *page = NULL; 28431da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 2844cc314eefSLinus Torvalds return page; 28451da177e4SLinus Torvalds } 28461da177e4SLinus Torvalds 2847cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 28481da177e4SLinus Torvalds { 2849cc314eefSLinus Torvalds struct page *page = cookie; 2850cc314eefSLinus Torvalds 2851cc314eefSLinus Torvalds if (page) { 28521da177e4SLinus Torvalds kunmap(page); 28531da177e4SLinus Torvalds page_cache_release(page); 28541da177e4SLinus Torvalds } 28551da177e4SLinus Torvalds } 28561da177e4SLinus Torvalds 285754566b2cSNick Piggin /* 285854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 285954566b2cSNick Piggin */ 286054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 28611da177e4SLinus Torvalds { 28621da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 28630adb25d2SKirill Korotaev struct page *page; 2864afddba49SNick Piggin void *fsdata; 2865beb497abSDmitriy Monakhov int err; 28661da177e4SLinus Torvalds char *kaddr; 286754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 286854566b2cSNick Piggin if (nofs) 286954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 28701da177e4SLinus Torvalds 28717e53cac4SNeilBrown retry: 2872afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 287354566b2cSNick Piggin flags, &page, &fsdata); 28741da177e4SLinus Torvalds if (err) 2875afddba49SNick Piggin goto fail; 2876afddba49SNick Piggin 28771da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 28781da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 28791da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 2880afddba49SNick Piggin 2881afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 2882afddba49SNick Piggin page, fsdata); 28831da177e4SLinus Torvalds if (err < 0) 28841da177e4SLinus Torvalds goto fail; 2885afddba49SNick Piggin if (err < len-1) 2886afddba49SNick Piggin goto retry; 2887afddba49SNick Piggin 28881da177e4SLinus Torvalds mark_inode_dirty(inode); 28891da177e4SLinus Torvalds return 0; 28901da177e4SLinus Torvalds fail: 28911da177e4SLinus Torvalds return err; 28921da177e4SLinus Torvalds } 28931da177e4SLinus Torvalds 28940adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 28950adb25d2SKirill Korotaev { 28960adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 289754566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 28980adb25d2SKirill Korotaev } 28990adb25d2SKirill Korotaev 290092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 29011da177e4SLinus Torvalds .readlink = generic_readlink, 29021da177e4SLinus Torvalds .follow_link = page_follow_link_light, 29031da177e4SLinus Torvalds .put_link = page_put_link, 29041da177e4SLinus Torvalds }; 29051da177e4SLinus Torvalds 29062d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 29071da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 29081da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 29091da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 29101da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 29111da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 29121da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 29131da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 29141da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 29151da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 29160adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 29171da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 29181da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 29191da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 2920d1811465SAl Viro EXPORT_SYMBOL(kern_path); 292116f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 2922f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 29238c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 29241da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 29251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 29261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 29271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 29281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 29291da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 29301da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 29311da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 29321da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 29331da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 29341da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 29351da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 29361da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 29371da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 2938