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 */ 172b74c79e9SNick Piggin static int acl_permission_check(struct inode *inode, int mask, unsigned int flags, 173b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 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) { 183b74c79e9SNick Piggin int error = check_acl(inode, mask, flags); 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 20539191628SRandy Dunlap * @flags: IPERM_FLAG_ flags. 2061da177e4SLinus Torvalds * 2071da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2081da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2091da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 210b74c79e9SNick Piggin * are used for other things. 211b74c79e9SNick Piggin * 212b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 213b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 214b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2151da177e4SLinus Torvalds */ 216b74c79e9SNick Piggin int generic_permission(struct inode *inode, int mask, unsigned int flags, 217b74c79e9SNick Piggin int (*check_acl)(struct inode *inode, int mask, unsigned int flags)) 2181da177e4SLinus Torvalds { 2195909ccaaSLinus Torvalds int ret; 2201da177e4SLinus Torvalds 2211da177e4SLinus Torvalds /* 2225909ccaaSLinus Torvalds * Do the basic POSIX ACL permission checks. 2231da177e4SLinus Torvalds */ 224b74c79e9SNick Piggin ret = acl_permission_check(inode, mask, flags, check_acl); 2255909ccaaSLinus Torvalds if (ret != -EACCES) 2265909ccaaSLinus Torvalds return ret; 2271da177e4SLinus Torvalds 2281da177e4SLinus Torvalds /* 2291da177e4SLinus Torvalds * Read/write DACs are always overridable. 2301da177e4SLinus Torvalds * Executable DACs are overridable if at least one exec bit is set. 2311da177e4SLinus Torvalds */ 232f696a365SMiklos Szeredi if (!(mask & MAY_EXEC) || execute_ok(inode)) 2331da177e4SLinus Torvalds if (capable(CAP_DAC_OVERRIDE)) 2341da177e4SLinus Torvalds return 0; 2351da177e4SLinus Torvalds 2361da177e4SLinus Torvalds /* 2371da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2381da177e4SLinus Torvalds */ 2397ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 2401da177e4SLinus Torvalds if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) 2411da177e4SLinus Torvalds if (capable(CAP_DAC_READ_SEARCH)) 2421da177e4SLinus Torvalds return 0; 2431da177e4SLinus Torvalds 2441da177e4SLinus Torvalds return -EACCES; 2451da177e4SLinus Torvalds } 2461da177e4SLinus Torvalds 247cb23beb5SChristoph Hellwig /** 248cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 249cb23beb5SChristoph Hellwig * @inode: inode to check permission on 250cb23beb5SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 251cb23beb5SChristoph Hellwig * 252cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 253cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 254cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 255cb23beb5SChristoph Hellwig * are used for other things. 256cb23beb5SChristoph Hellwig */ 257f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 2581da177e4SLinus Torvalds { 259e6305c43SAl Viro int retval; 2601da177e4SLinus Torvalds 2611da177e4SLinus Torvalds if (mask & MAY_WRITE) { 26222590e41SMiklos Szeredi umode_t mode = inode->i_mode; 2631da177e4SLinus Torvalds 2641da177e4SLinus Torvalds /* 2651da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 2661da177e4SLinus Torvalds */ 2671da177e4SLinus Torvalds if (IS_RDONLY(inode) && 2681da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 2691da177e4SLinus Torvalds return -EROFS; 2701da177e4SLinus Torvalds 2711da177e4SLinus Torvalds /* 2721da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 2731da177e4SLinus Torvalds */ 2741da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 2751da177e4SLinus Torvalds return -EACCES; 2761da177e4SLinus Torvalds } 2771da177e4SLinus Torvalds 278acfa4380SAl Viro if (inode->i_op->permission) 279b74c79e9SNick Piggin retval = inode->i_op->permission(inode, mask, 0); 280f696a365SMiklos Szeredi else 281b74c79e9SNick Piggin retval = generic_permission(inode, mask, 0, 282b74c79e9SNick Piggin inode->i_op->check_acl); 283f696a365SMiklos Szeredi 2841da177e4SLinus Torvalds if (retval) 2851da177e4SLinus Torvalds return retval; 2861da177e4SLinus Torvalds 28708ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 28808ce5f16SSerge E. Hallyn if (retval) 28908ce5f16SSerge E. Hallyn return retval; 29008ce5f16SSerge E. Hallyn 291d09ca739SEric Paris return security_inode_permission(inode, mask); 2921da177e4SLinus Torvalds } 2931da177e4SLinus Torvalds 294e4543eddSChristoph Hellwig /** 2958c744fb8SChristoph Hellwig * file_permission - check for additional access rights to a given file 2968c744fb8SChristoph Hellwig * @file: file to check access rights for 2978c744fb8SChristoph Hellwig * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 2988c744fb8SChristoph Hellwig * 2998c744fb8SChristoph Hellwig * Used to check for read/write/execute permissions on an already opened 3008c744fb8SChristoph Hellwig * file. 3018c744fb8SChristoph Hellwig * 3028c744fb8SChristoph Hellwig * Note: 3038c744fb8SChristoph Hellwig * Do not use this function in new code. All access checks should 304cb23beb5SChristoph Hellwig * be done using inode_permission(). 3058c744fb8SChristoph Hellwig */ 3068c744fb8SChristoph Hellwig int file_permission(struct file *file, int mask) 3078c744fb8SChristoph Hellwig { 308f419a2e3SAl Viro return inode_permission(file->f_path.dentry->d_inode, mask); 3098c744fb8SChristoph Hellwig } 3108c744fb8SChristoph Hellwig 3111da177e4SLinus Torvalds /* 3121da177e4SLinus Torvalds * get_write_access() gets write permission for a file. 3131da177e4SLinus Torvalds * put_write_access() releases this write permission. 3141da177e4SLinus Torvalds * This is used for regular files. 3151da177e4SLinus Torvalds * We cannot support write (and maybe mmap read-write shared) accesses and 3161da177e4SLinus Torvalds * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode 3171da177e4SLinus Torvalds * can have the following values: 3181da177e4SLinus Torvalds * 0: no writers, no VM_DENYWRITE mappings 3191da177e4SLinus Torvalds * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist 3201da177e4SLinus Torvalds * > 0: (i_writecount) users are writing to the file. 3211da177e4SLinus Torvalds * 3221da177e4SLinus Torvalds * Normally we operate on that counter with atomic_{inc,dec} and it's safe 3231da177e4SLinus Torvalds * except for the cases where we don't hold i_writecount yet. Then we need to 3241da177e4SLinus Torvalds * use {get,deny}_write_access() - these functions check the sign and refuse 3251da177e4SLinus Torvalds * to do the change if sign is wrong. Exclusion between them is provided by 3261da177e4SLinus Torvalds * the inode->i_lock spinlock. 3271da177e4SLinus Torvalds */ 3281da177e4SLinus Torvalds 3291da177e4SLinus Torvalds int get_write_access(struct inode * inode) 3301da177e4SLinus Torvalds { 3311da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3321da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) < 0) { 3331da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3341da177e4SLinus Torvalds return -ETXTBSY; 3351da177e4SLinus Torvalds } 3361da177e4SLinus Torvalds atomic_inc(&inode->i_writecount); 3371da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3381da177e4SLinus Torvalds 3391da177e4SLinus Torvalds return 0; 3401da177e4SLinus Torvalds } 3411da177e4SLinus Torvalds 3421da177e4SLinus Torvalds int deny_write_access(struct file * file) 3431da177e4SLinus Torvalds { 3440f7fc9e4SJosef "Jeff" Sipek struct inode *inode = file->f_path.dentry->d_inode; 3451da177e4SLinus Torvalds 3461da177e4SLinus Torvalds spin_lock(&inode->i_lock); 3471da177e4SLinus Torvalds if (atomic_read(&inode->i_writecount) > 0) { 3481da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3491da177e4SLinus Torvalds return -ETXTBSY; 3501da177e4SLinus Torvalds } 3511da177e4SLinus Torvalds atomic_dec(&inode->i_writecount); 3521da177e4SLinus Torvalds spin_unlock(&inode->i_lock); 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds return 0; 3551da177e4SLinus Torvalds } 3561da177e4SLinus Torvalds 3571d957f9bSJan Blunck /** 3585dd784d0SJan Blunck * path_get - get a reference to a path 3595dd784d0SJan Blunck * @path: path to get the reference to 3605dd784d0SJan Blunck * 3615dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3625dd784d0SJan Blunck */ 3635dd784d0SJan Blunck void path_get(struct path *path) 3645dd784d0SJan Blunck { 3655dd784d0SJan Blunck mntget(path->mnt); 3665dd784d0SJan Blunck dget(path->dentry); 3675dd784d0SJan Blunck } 3685dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3695dd784d0SJan Blunck 3705dd784d0SJan Blunck /** 371b3e19d92SNick Piggin * path_get_long - get a long reference to a path 372b3e19d92SNick Piggin * @path: path to get the reference to 373b3e19d92SNick Piggin * 374b3e19d92SNick Piggin * Given a path increment the reference count to the dentry and the vfsmount. 375b3e19d92SNick Piggin */ 376b3e19d92SNick Piggin void path_get_long(struct path *path) 377b3e19d92SNick Piggin { 378b3e19d92SNick Piggin mntget_long(path->mnt); 379b3e19d92SNick Piggin dget(path->dentry); 380b3e19d92SNick Piggin } 381b3e19d92SNick Piggin 382b3e19d92SNick Piggin /** 3831d957f9bSJan Blunck * path_put - put a reference to a path 3841d957f9bSJan Blunck * @path: path to put the reference to 3851d957f9bSJan Blunck * 3861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3871d957f9bSJan Blunck */ 3881d957f9bSJan Blunck void path_put(struct path *path) 3891da177e4SLinus Torvalds { 3901d957f9bSJan Blunck dput(path->dentry); 3911d957f9bSJan Blunck mntput(path->mnt); 3921da177e4SLinus Torvalds } 3931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3941da177e4SLinus Torvalds 395834f2a4aSTrond Myklebust /** 396b3e19d92SNick Piggin * path_put_long - put a long reference to a path 397b3e19d92SNick Piggin * @path: path to put the reference to 398b3e19d92SNick Piggin * 399b3e19d92SNick Piggin * Given a path decrement the reference count to the dentry and the vfsmount. 400b3e19d92SNick Piggin */ 401b3e19d92SNick Piggin void path_put_long(struct path *path) 402b3e19d92SNick Piggin { 403b3e19d92SNick Piggin dput(path->dentry); 404b3e19d92SNick Piggin mntput_long(path->mnt); 405b3e19d92SNick Piggin } 406b3e19d92SNick Piggin 407b3e19d92SNick Piggin /** 40831e6b01fSNick Piggin * nameidata_drop_rcu - drop this nameidata out of rcu-walk 40931e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 41039191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 41131e6b01fSNick Piggin * 41231e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 41331e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). __drop_rcu* functions attempt 41431e6b01fSNick Piggin * to drop out of rcu-walk mode and take normal reference counts on dentries 41531e6b01fSNick Piggin * and vfsmounts to transition to rcu-walk mode. __drop_rcu* functions take 41631e6b01fSNick Piggin * refcounts at the last known good point before rcu-walk got stuck, so 41731e6b01fSNick Piggin * ref-walk may continue from there. If this is not successful (eg. a seqcount 41831e6b01fSNick Piggin * has changed), then failure is returned and path walk restarts from the 41931e6b01fSNick Piggin * beginning in ref-walk mode. 42031e6b01fSNick Piggin * 42131e6b01fSNick Piggin * nameidata_drop_rcu attempts to drop the current nd->path and nd->root into 42231e6b01fSNick Piggin * ref-walk. Must be called from rcu-walk context. 42331e6b01fSNick Piggin */ 42431e6b01fSNick Piggin static int nameidata_drop_rcu(struct nameidata *nd) 42531e6b01fSNick Piggin { 42631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 42731e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 42831e6b01fSNick Piggin 42931e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 43031e6b01fSNick Piggin if (nd->root.mnt) { 43131e6b01fSNick Piggin spin_lock(&fs->lock); 43231e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 43331e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 43431e6b01fSNick Piggin goto err_root; 43531e6b01fSNick Piggin } 43631e6b01fSNick Piggin spin_lock(&dentry->d_lock); 43731e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 43831e6b01fSNick Piggin goto err; 43931e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 44031e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 44131e6b01fSNick Piggin if (nd->root.mnt) { 44231e6b01fSNick Piggin path_get(&nd->root); 44331e6b01fSNick Piggin spin_unlock(&fs->lock); 44431e6b01fSNick Piggin } 44531e6b01fSNick Piggin mntget(nd->path.mnt); 44631e6b01fSNick Piggin 44731e6b01fSNick Piggin rcu_read_unlock(); 44831e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 44931e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 45031e6b01fSNick Piggin return 0; 45131e6b01fSNick Piggin err: 45231e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 45331e6b01fSNick Piggin err_root: 45431e6b01fSNick Piggin if (nd->root.mnt) 45531e6b01fSNick Piggin spin_unlock(&fs->lock); 45631e6b01fSNick Piggin return -ECHILD; 45731e6b01fSNick Piggin } 45831e6b01fSNick Piggin 45931e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 46031e6b01fSNick Piggin static inline int nameidata_drop_rcu_maybe(struct nameidata *nd) 46131e6b01fSNick Piggin { 46231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) 46331e6b01fSNick Piggin return nameidata_drop_rcu(nd); 46431e6b01fSNick Piggin return 0; 46531e6b01fSNick Piggin } 46631e6b01fSNick Piggin 46731e6b01fSNick Piggin /** 46831e6b01fSNick Piggin * nameidata_dentry_drop_rcu - drop nameidata and dentry out of rcu-walk 46931e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 47031e6b01fSNick Piggin * @dentry: dentry to drop 47139191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 47231e6b01fSNick Piggin * 47331e6b01fSNick Piggin * nameidata_dentry_drop_rcu attempts to drop the current nd->path and nd->root, 47431e6b01fSNick Piggin * and dentry into ref-walk. @dentry must be a path found by a do_lookup call on 47531e6b01fSNick Piggin * @nd. Must be called from rcu-walk context. 47631e6b01fSNick Piggin */ 47731e6b01fSNick Piggin static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry) 47831e6b01fSNick Piggin { 47931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 48031e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 48131e6b01fSNick Piggin 48290dbb77bSNick Piggin /* 48390dbb77bSNick Piggin * It can be possible to revalidate the dentry that we started 48490dbb77bSNick Piggin * the path walk with. force_reval_path may also revalidate the 48590dbb77bSNick Piggin * dentry already committed to the nameidata. 48690dbb77bSNick Piggin */ 48790dbb77bSNick Piggin if (unlikely(parent == dentry)) 48890dbb77bSNick Piggin return nameidata_drop_rcu(nd); 48990dbb77bSNick Piggin 49031e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 49131e6b01fSNick Piggin if (nd->root.mnt) { 49231e6b01fSNick Piggin spin_lock(&fs->lock); 49331e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 49431e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 49531e6b01fSNick Piggin goto err_root; 49631e6b01fSNick Piggin } 49731e6b01fSNick Piggin spin_lock(&parent->d_lock); 49831e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 49931e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 50031e6b01fSNick Piggin goto err; 50131e6b01fSNick Piggin /* 50231e6b01fSNick Piggin * If the sequence check on the child dentry passed, then the child has 50331e6b01fSNick Piggin * not been removed from its parent. This means the parent dentry must 50431e6b01fSNick Piggin * be valid and able to take a reference at this point. 50531e6b01fSNick Piggin */ 50631e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 50731e6b01fSNick Piggin BUG_ON(!parent->d_count); 50831e6b01fSNick Piggin parent->d_count++; 50931e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 51031e6b01fSNick Piggin spin_unlock(&parent->d_lock); 51131e6b01fSNick Piggin if (nd->root.mnt) { 51231e6b01fSNick Piggin path_get(&nd->root); 51331e6b01fSNick Piggin spin_unlock(&fs->lock); 51431e6b01fSNick Piggin } 51531e6b01fSNick Piggin mntget(nd->path.mnt); 51631e6b01fSNick Piggin 51731e6b01fSNick Piggin rcu_read_unlock(); 51831e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 51931e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 52031e6b01fSNick Piggin return 0; 52131e6b01fSNick Piggin err: 52231e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 52331e6b01fSNick Piggin spin_unlock(&parent->d_lock); 52431e6b01fSNick Piggin err_root: 52531e6b01fSNick Piggin if (nd->root.mnt) 52631e6b01fSNick Piggin spin_unlock(&fs->lock); 52731e6b01fSNick Piggin return -ECHILD; 52831e6b01fSNick Piggin } 52931e6b01fSNick Piggin 53031e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 53131e6b01fSNick Piggin static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry) 53231e6b01fSNick Piggin { 53331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) 53431e6b01fSNick Piggin return nameidata_dentry_drop_rcu(nd, dentry); 53531e6b01fSNick Piggin return 0; 53631e6b01fSNick Piggin } 53731e6b01fSNick Piggin 53831e6b01fSNick Piggin /** 53931e6b01fSNick Piggin * nameidata_drop_rcu_last - drop nameidata ending path walk out of rcu-walk 54031e6b01fSNick Piggin * @nd: nameidata pathwalk data to drop 54139191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 54231e6b01fSNick Piggin * 54331e6b01fSNick Piggin * nameidata_drop_rcu_last attempts to drop the current nd->path into ref-walk. 54431e6b01fSNick Piggin * nd->path should be the final element of the lookup, so nd->root is discarded. 54531e6b01fSNick Piggin * Must be called from rcu-walk context. 54631e6b01fSNick Piggin */ 54731e6b01fSNick Piggin static int nameidata_drop_rcu_last(struct nameidata *nd) 54831e6b01fSNick Piggin { 54931e6b01fSNick Piggin struct dentry *dentry = nd->path.dentry; 55031e6b01fSNick Piggin 55131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 55231e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 55331e6b01fSNick Piggin nd->root.mnt = NULL; 55431e6b01fSNick Piggin spin_lock(&dentry->d_lock); 55531e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 55631e6b01fSNick Piggin goto err_unlock; 55731e6b01fSNick Piggin BUG_ON(nd->inode != dentry->d_inode); 55831e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 55931e6b01fSNick Piggin 56031e6b01fSNick Piggin mntget(nd->path.mnt); 56131e6b01fSNick Piggin 56231e6b01fSNick Piggin rcu_read_unlock(); 56331e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 56431e6b01fSNick Piggin 56531e6b01fSNick Piggin return 0; 56631e6b01fSNick Piggin 56731e6b01fSNick Piggin err_unlock: 56831e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 56931e6b01fSNick Piggin rcu_read_unlock(); 57031e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 57131e6b01fSNick Piggin return -ECHILD; 57231e6b01fSNick Piggin } 57331e6b01fSNick Piggin 57431e6b01fSNick Piggin /* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing. */ 57531e6b01fSNick Piggin static inline int nameidata_drop_rcu_last_maybe(struct nameidata *nd) 57631e6b01fSNick Piggin { 57731e6b01fSNick Piggin if (likely(nd->flags & LOOKUP_RCU)) 57831e6b01fSNick Piggin return nameidata_drop_rcu_last(nd); 57931e6b01fSNick Piggin return 0; 58031e6b01fSNick Piggin } 58131e6b01fSNick Piggin 58231e6b01fSNick Piggin /** 583834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 584834f2a4aSTrond Myklebust * @nd: pointer to nameidata 585834f2a4aSTrond Myklebust */ 586834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 587834f2a4aSTrond Myklebust { 5880f7fc9e4SJosef "Jeff" Sipek if (nd->intent.open.file->f_path.dentry == NULL) 589834f2a4aSTrond Myklebust put_filp(nd->intent.open.file); 590834f2a4aSTrond Myklebust else 591834f2a4aSTrond Myklebust fput(nd->intent.open.file); 592834f2a4aSTrond Myklebust } 593834f2a4aSTrond Myklebust 594bb20c18dSNick Piggin /* 595bb20c18dSNick Piggin * Call d_revalidate and handle filesystems that request rcu-walk 596bb20c18dSNick Piggin * to be dropped. This may be called and return in rcu-walk mode, 597bb20c18dSNick Piggin * regardless of success or error. If -ECHILD is returned, the caller 598bb20c18dSNick Piggin * must return -ECHILD back up the path walk stack so path walk may 599bb20c18dSNick Piggin * be restarted in ref-walk mode. 600bb20c18dSNick Piggin */ 60134286d66SNick Piggin static int d_revalidate(struct dentry *dentry, struct nameidata *nd) 60234286d66SNick Piggin { 60334286d66SNick Piggin int status; 60434286d66SNick Piggin 60534286d66SNick Piggin status = dentry->d_op->d_revalidate(dentry, nd); 60634286d66SNick Piggin if (status == -ECHILD) { 60734286d66SNick Piggin if (nameidata_dentry_drop_rcu(nd, dentry)) 60834286d66SNick Piggin return status; 60934286d66SNick Piggin status = dentry->d_op->d_revalidate(dentry, nd); 61034286d66SNick Piggin } 61134286d66SNick Piggin 61234286d66SNick Piggin return status; 61334286d66SNick Piggin } 61434286d66SNick Piggin 615bcdc5e01SIan Kent static inline struct dentry * 616bcdc5e01SIan Kent do_revalidate(struct dentry *dentry, struct nameidata *nd) 617bcdc5e01SIan Kent { 61834286d66SNick Piggin int status; 61934286d66SNick Piggin 62034286d66SNick Piggin status = d_revalidate(dentry, nd); 621bcdc5e01SIan Kent if (unlikely(status <= 0)) { 622bcdc5e01SIan Kent /* 623bcdc5e01SIan Kent * The dentry failed validation. 624bcdc5e01SIan Kent * If d_revalidate returned 0 attempt to invalidate 625bcdc5e01SIan Kent * the dentry otherwise d_revalidate is asking us 626bcdc5e01SIan Kent * to return a fail status. 627bcdc5e01SIan Kent */ 62834286d66SNick Piggin if (status < 0) { 62934286d66SNick Piggin /* If we're in rcu-walk, we don't have a ref */ 63034286d66SNick Piggin if (!(nd->flags & LOOKUP_RCU)) 63134286d66SNick Piggin dput(dentry); 63234286d66SNick Piggin dentry = ERR_PTR(status); 63334286d66SNick Piggin 63434286d66SNick Piggin } else { 63534286d66SNick Piggin /* Don't d_invalidate in rcu-walk mode */ 63634286d66SNick Piggin if (nameidata_dentry_drop_rcu_maybe(nd, dentry)) 63734286d66SNick Piggin return ERR_PTR(-ECHILD); 638bcdc5e01SIan Kent if (!d_invalidate(dentry)) { 639bcdc5e01SIan Kent dput(dentry); 640bcdc5e01SIan Kent dentry = NULL; 641bcdc5e01SIan Kent } 642bcdc5e01SIan Kent } 643bcdc5e01SIan Kent } 644bcdc5e01SIan Kent return dentry; 645bcdc5e01SIan Kent } 646bcdc5e01SIan Kent 647fb045adbSNick Piggin static inline int need_reval_dot(struct dentry *dentry) 648fb045adbSNick Piggin { 649fb045adbSNick Piggin if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 650fb045adbSNick Piggin return 0; 651fb045adbSNick Piggin 652fb045adbSNick Piggin if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 653fb045adbSNick Piggin return 0; 654fb045adbSNick Piggin 655fb045adbSNick Piggin return 1; 656fb045adbSNick Piggin } 657fb045adbSNick Piggin 6581da177e4SLinus Torvalds /* 65939159de2SJeff Layton * force_reval_path - force revalidation of a dentry 66039159de2SJeff Layton * 66139159de2SJeff Layton * In some situations the path walking code will trust dentries without 66239159de2SJeff Layton * revalidating them. This causes problems for filesystems that depend on 66339159de2SJeff Layton * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set 66439159de2SJeff Layton * (which indicates that it's possible for the dentry to go stale), force 66539159de2SJeff Layton * a d_revalidate call before proceeding. 66639159de2SJeff Layton * 66739159de2SJeff Layton * Returns 0 if the revalidation was successful. If the revalidation fails, 66839159de2SJeff Layton * either return the error returned by d_revalidate or -ESTALE if the 66939159de2SJeff Layton * revalidation it just returned 0. If d_revalidate returns 0, we attempt to 67039159de2SJeff Layton * invalidate the dentry. It's up to the caller to handle putting references 67139159de2SJeff Layton * to the path if necessary. 67239159de2SJeff Layton */ 67339159de2SJeff Layton static int 67439159de2SJeff Layton force_reval_path(struct path *path, struct nameidata *nd) 67539159de2SJeff Layton { 67639159de2SJeff Layton int status; 67739159de2SJeff Layton struct dentry *dentry = path->dentry; 67839159de2SJeff Layton 67939159de2SJeff Layton /* 68039159de2SJeff Layton * only check on filesystems where it's possible for the dentry to 681fb045adbSNick Piggin * become stale. 68239159de2SJeff Layton */ 683fb045adbSNick Piggin if (!need_reval_dot(dentry)) 68439159de2SJeff Layton return 0; 68539159de2SJeff Layton 68634286d66SNick Piggin status = d_revalidate(dentry, nd); 68739159de2SJeff Layton if (status > 0) 68839159de2SJeff Layton return 0; 68939159de2SJeff Layton 69039159de2SJeff Layton if (!status) { 691bb20c18dSNick Piggin /* Don't d_invalidate in rcu-walk mode */ 692bb20c18dSNick Piggin if (nameidata_drop_rcu(nd)) 693bb20c18dSNick Piggin return -ECHILD; 69439159de2SJeff Layton d_invalidate(dentry); 69539159de2SJeff Layton status = -ESTALE; 69639159de2SJeff Layton } 69739159de2SJeff Layton return status; 69839159de2SJeff Layton } 69939159de2SJeff Layton 70039159de2SJeff Layton /* 701b75b5086SAl Viro * Short-cut version of permission(), for calling on directories 702b75b5086SAl Viro * during pathname resolution. Combines parts of permission() 703b75b5086SAl Viro * and generic_permission(), and tests ONLY for MAY_EXEC permission. 7041da177e4SLinus Torvalds * 7051da177e4SLinus Torvalds * If appropriate, check DAC only. If not appropriate, or 706b75b5086SAl Viro * short-cut DAC fails, then call ->permission() to do more 7071da177e4SLinus Torvalds * complete permission check. 7081da177e4SLinus Torvalds */ 709b74c79e9SNick Piggin static inline int exec_permission(struct inode *inode, unsigned int flags) 7101da177e4SLinus Torvalds { 7115909ccaaSLinus Torvalds int ret; 7121da177e4SLinus Torvalds 713cb9179eaSLinus Torvalds if (inode->i_op->permission) { 714b74c79e9SNick Piggin ret = inode->i_op->permission(inode, MAY_EXEC, flags); 715b74c79e9SNick Piggin } else { 716b74c79e9SNick Piggin ret = acl_permission_check(inode, MAY_EXEC, flags, 717b74c79e9SNick Piggin inode->i_op->check_acl); 718cb9179eaSLinus Torvalds } 719b74c79e9SNick Piggin if (likely(!ret)) 7201da177e4SLinus Torvalds goto ok; 721b74c79e9SNick Piggin if (ret == -ECHILD) 72231e6b01fSNick Piggin return ret; 7231da177e4SLinus Torvalds 724f1ac9f6bSLinus Torvalds if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) 7251da177e4SLinus Torvalds goto ok; 7261da177e4SLinus Torvalds 7275909ccaaSLinus Torvalds return ret; 7281da177e4SLinus Torvalds ok: 729b74c79e9SNick Piggin return security_inode_exec_permission(inode, flags); 7301da177e4SLinus Torvalds } 7311da177e4SLinus Torvalds 7322a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7332a737871SAl Viro { 734f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 735f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7362a737871SAl Viro } 7372a737871SAl Viro 7386de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 7396de88d72SAl Viro 74031e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 74131e6b01fSNick Piggin { 74231e6b01fSNick Piggin if (!nd->root.mnt) { 74331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 744c28cc364SNick Piggin unsigned seq; 745c28cc364SNick Piggin 746c28cc364SNick Piggin do { 747c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 74831e6b01fSNick Piggin nd->root = fs->root; 749c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 75031e6b01fSNick Piggin } 75131e6b01fSNick Piggin } 75231e6b01fSNick Piggin 753f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 7541da177e4SLinus Torvalds { 75531e6b01fSNick Piggin int ret; 75631e6b01fSNick Piggin 7571da177e4SLinus Torvalds if (IS_ERR(link)) 7581da177e4SLinus Torvalds goto fail; 7591da177e4SLinus Torvalds 7601da177e4SLinus Torvalds if (*link == '/') { 7612a737871SAl Viro set_root(nd); 7621d957f9bSJan Blunck path_put(&nd->path); 7632a737871SAl Viro nd->path = nd->root; 7642a737871SAl Viro path_get(&nd->root); 7651da177e4SLinus Torvalds } 76631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 767b4091d5fSChristoph Hellwig 76831e6b01fSNick Piggin ret = link_path_walk(link, nd); 76931e6b01fSNick Piggin return ret; 7701da177e4SLinus Torvalds fail: 7711d957f9bSJan Blunck path_put(&nd->path); 7721da177e4SLinus Torvalds return PTR_ERR(link); 7731da177e4SLinus Torvalds } 7741da177e4SLinus Torvalds 7751d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 776051d3812SIan Kent { 777051d3812SIan Kent dput(path->dentry); 7784ac91378SJan Blunck if (path->mnt != nd->path.mnt) 779051d3812SIan Kent mntput(path->mnt); 780051d3812SIan Kent } 781051d3812SIan Kent 7827b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7837b9337aaSNick Piggin struct nameidata *nd) 784051d3812SIan Kent { 78531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7864ac91378SJan Blunck dput(nd->path.dentry); 78731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7884ac91378SJan Blunck mntput(nd->path.mnt); 7899a229683SHuang Shijie } 79031e6b01fSNick Piggin nd->path.mnt = path->mnt; 7914ac91378SJan Blunck nd->path.dentry = path->dentry; 792051d3812SIan Kent } 793051d3812SIan Kent 794def4af30SAl Viro static __always_inline int 7957b9337aaSNick Piggin __do_follow_link(const struct path *link, struct nameidata *nd, void **p) 7961da177e4SLinus Torvalds { 7971da177e4SLinus Torvalds int error; 7987b9337aaSNick Piggin struct dentry *dentry = link->dentry; 7991da177e4SLinus Torvalds 8007b9337aaSNick Piggin touch_atime(link->mnt, dentry); 8011da177e4SLinus Torvalds nd_set_link(nd, NULL); 802cd4e91d3SAl Viro 8037b9337aaSNick Piggin if (link->mnt != nd->path.mnt) { 8047b9337aaSNick Piggin path_to_nameidata(link, nd); 80531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 806051d3812SIan Kent dget(dentry); 807051d3812SIan Kent } 8087b9337aaSNick Piggin mntget(link->mnt); 80931e6b01fSNick Piggin 81086acdca1SAl Viro nd->last_type = LAST_BIND; 811def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 812def4af30SAl Viro error = PTR_ERR(*p); 813def4af30SAl Viro if (!IS_ERR(*p)) { 8141da177e4SLinus Torvalds char *s = nd_get_link(nd); 815cc314eefSLinus Torvalds error = 0; 8161da177e4SLinus Torvalds if (s) 8171da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 81839159de2SJeff Layton else if (nd->last_type == LAST_BIND) { 81939159de2SJeff Layton error = force_reval_path(&nd->path, nd); 82039159de2SJeff Layton if (error) 82139159de2SJeff Layton path_put(&nd->path); 82239159de2SJeff Layton } 8231da177e4SLinus Torvalds } 8241da177e4SLinus Torvalds return error; 8251da177e4SLinus Torvalds } 8261da177e4SLinus Torvalds 8271da177e4SLinus Torvalds /* 8281da177e4SLinus Torvalds * This limits recursive symlink follows to 8, while 8291da177e4SLinus Torvalds * limiting consecutive symlinks to 40. 8301da177e4SLinus Torvalds * 8311da177e4SLinus Torvalds * Without that kind of total limit, nasty chains of consecutive 8321da177e4SLinus Torvalds * symlinks can cause almost arbitrarily long lookups. 8331da177e4SLinus Torvalds */ 83490ebe565SAl Viro static inline int do_follow_link(struct path *path, struct nameidata *nd) 8351da177e4SLinus Torvalds { 836def4af30SAl Viro void *cookie; 8371da177e4SLinus Torvalds int err = -ELOOP; 8381da177e4SLinus Torvalds if (current->link_count >= MAX_NESTED_LINKS) 8391da177e4SLinus Torvalds goto loop; 8401da177e4SLinus Torvalds if (current->total_link_count >= 40) 8411da177e4SLinus Torvalds goto loop; 8421da177e4SLinus Torvalds BUG_ON(nd->depth >= MAX_NESTED_LINKS); 8431da177e4SLinus Torvalds cond_resched(); 84490ebe565SAl Viro err = security_inode_follow_link(path->dentry, nd); 8451da177e4SLinus Torvalds if (err) 8461da177e4SLinus Torvalds goto loop; 8471da177e4SLinus Torvalds current->link_count++; 8481da177e4SLinus Torvalds current->total_link_count++; 8491da177e4SLinus Torvalds nd->depth++; 850def4af30SAl Viro err = __do_follow_link(path, nd, &cookie); 851def4af30SAl Viro if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link) 852def4af30SAl Viro path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie); 853258fa999SAl Viro path_put(path); 8541da177e4SLinus Torvalds current->link_count--; 8551da177e4SLinus Torvalds nd->depth--; 8561da177e4SLinus Torvalds return err; 8571da177e4SLinus Torvalds loop: 8581d957f9bSJan Blunck path_put_conditional(path, nd); 8591d957f9bSJan Blunck path_put(&nd->path); 8601da177e4SLinus Torvalds return err; 8611da177e4SLinus Torvalds } 8621da177e4SLinus Torvalds 86331e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 86431e6b01fSNick Piggin { 86531e6b01fSNick Piggin struct vfsmount *parent; 86631e6b01fSNick Piggin struct dentry *mountpoint; 86731e6b01fSNick Piggin 86831e6b01fSNick Piggin parent = path->mnt->mnt_parent; 86931e6b01fSNick Piggin if (parent == path->mnt) 87031e6b01fSNick Piggin return 0; 87131e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 87231e6b01fSNick Piggin path->dentry = mountpoint; 87331e6b01fSNick Piggin path->mnt = parent; 87431e6b01fSNick Piggin return 1; 87531e6b01fSNick Piggin } 87631e6b01fSNick Piggin 877bab77ebfSAl Viro int follow_up(struct path *path) 8781da177e4SLinus Torvalds { 8791da177e4SLinus Torvalds struct vfsmount *parent; 8801da177e4SLinus Torvalds struct dentry *mountpoint; 88199b7db7bSNick Piggin 88299b7db7bSNick Piggin br_read_lock(vfsmount_lock); 883bab77ebfSAl Viro parent = path->mnt->mnt_parent; 884bab77ebfSAl Viro if (parent == path->mnt) { 88599b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 8861da177e4SLinus Torvalds return 0; 8871da177e4SLinus Torvalds } 8881da177e4SLinus Torvalds mntget(parent); 889bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 89099b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 891bab77ebfSAl Viro dput(path->dentry); 892bab77ebfSAl Viro path->dentry = mountpoint; 893bab77ebfSAl Viro mntput(path->mnt); 894bab77ebfSAl Viro path->mnt = parent; 8951da177e4SLinus Torvalds return 1; 8961da177e4SLinus Torvalds } 8971da177e4SLinus Torvalds 898b5c84bf6SNick Piggin /* 8999875cf80SDavid Howells * Perform an automount 9009875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9019875cf80SDavid Howells * were called with. 9021da177e4SLinus Torvalds */ 9039875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9049875cf80SDavid Howells bool *need_mntput) 90531e6b01fSNick Piggin { 9069875cf80SDavid Howells struct vfsmount *mnt; 9079875cf80SDavid Howells 9089875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9099875cf80SDavid Howells return -EREMOTE; 9109875cf80SDavid Howells 9119875cf80SDavid Howells /* We want to mount if someone is trying to open/create a file of any 9129875cf80SDavid Howells * type under the mountpoint, wants to traverse through the mountpoint 9139875cf80SDavid Howells * or wants to open the mounted directory. 9149875cf80SDavid Howells * 9159875cf80SDavid Howells * We don't want to mount if someone's just doing a stat and they've 9169875cf80SDavid Howells * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and 9179875cf80SDavid Howells * appended a '/' to the name. 9189875cf80SDavid Howells */ 9199875cf80SDavid Howells if (!(flags & LOOKUP_FOLLOW) && 9209875cf80SDavid Howells !(flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY | 9219875cf80SDavid Howells LOOKUP_OPEN | LOOKUP_CREATE))) 9229875cf80SDavid Howells return -EISDIR; 9239875cf80SDavid Howells 9249875cf80SDavid Howells current->total_link_count++; 9259875cf80SDavid Howells if (current->total_link_count >= 40) 9269875cf80SDavid Howells return -ELOOP; 9279875cf80SDavid Howells 9289875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9299875cf80SDavid Howells if (IS_ERR(mnt)) { 9309875cf80SDavid Howells /* 9319875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9329875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9339875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9349875cf80SDavid Howells * 9359875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9369875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9379875cf80SDavid Howells * the path is inaccessible and we should say so. 9389875cf80SDavid Howells */ 9399875cf80SDavid Howells if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_CONTINUE)) 9409875cf80SDavid Howells return -EREMOTE; 9419875cf80SDavid Howells return PTR_ERR(mnt); 94231e6b01fSNick Piggin } 9439875cf80SDavid Howells if (!mnt) /* mount collision */ 9449875cf80SDavid Howells return 0; 9459875cf80SDavid Howells 9469875cf80SDavid Howells if (mnt->mnt_sb == path->mnt->mnt_sb && 9479875cf80SDavid Howells mnt->mnt_root == path->dentry) { 9489875cf80SDavid Howells mntput(mnt); 9499875cf80SDavid Howells return -ELOOP; 95031e6b01fSNick Piggin } 95131e6b01fSNick Piggin 952463ffb2eSAl Viro dput(path->dentry); 9539875cf80SDavid Howells if (*need_mntput) 9549875cf80SDavid Howells mntput(path->mnt); 9559875cf80SDavid Howells path->mnt = mnt; 9569875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9579875cf80SDavid Howells *need_mntput = true; 9589875cf80SDavid Howells return 0; 9599875cf80SDavid Howells } 9609875cf80SDavid Howells 9619875cf80SDavid Howells /* 9629875cf80SDavid Howells * Handle a dentry that is managed in some way. 963cc53ce53SDavid Howells * - Flagged for transit management (autofs) 9649875cf80SDavid Howells * - Flagged as mountpoint 9659875cf80SDavid Howells * - Flagged as automount point 9669875cf80SDavid Howells * 9679875cf80SDavid Howells * This may only be called in refwalk mode. 9689875cf80SDavid Howells * 9699875cf80SDavid Howells * Serialization is taken care of in namespace.c 9709875cf80SDavid Howells */ 9719875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 9729875cf80SDavid Howells { 9739875cf80SDavid Howells unsigned managed; 9749875cf80SDavid Howells bool need_mntput = false; 9759875cf80SDavid Howells int ret; 9769875cf80SDavid Howells 9779875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 9789875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 9799875cf80SDavid Howells * the components of that value change under us */ 9809875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 9819875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 9829875cf80SDavid Howells unlikely(managed != 0)) { 983cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 984cc53ce53SDavid Howells * being held. */ 985cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 986cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 987cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 988cc53ce53SDavid Howells ret = path->dentry->d_op->d_manage(path->dentry, false); 989cc53ce53SDavid Howells if (ret < 0) 990cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 991cc53ce53SDavid Howells } 992cc53ce53SDavid Howells 9939875cf80SDavid Howells /* Transit to a mounted filesystem. */ 9949875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 9959875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 9969875cf80SDavid Howells if (mounted) { 9979875cf80SDavid Howells dput(path->dentry); 9989875cf80SDavid Howells if (need_mntput) 999463ffb2eSAl Viro mntput(path->mnt); 1000463ffb2eSAl Viro path->mnt = mounted; 1001463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10029875cf80SDavid Howells need_mntput = true; 10039875cf80SDavid Howells continue; 1004463ffb2eSAl Viro } 1005463ffb2eSAl Viro 10069875cf80SDavid Howells /* Something is mounted on this dentry in another 10079875cf80SDavid Howells * namespace and/or whatever was mounted there in this 10089875cf80SDavid Howells * namespace got unmounted before we managed to get the 10099875cf80SDavid Howells * vfsmount_lock */ 10101da177e4SLinus Torvalds } 10119875cf80SDavid Howells 10129875cf80SDavid Howells /* Handle an automount point */ 10139875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10149875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10159875cf80SDavid Howells if (ret < 0) 10169875cf80SDavid Howells return ret == -EISDIR ? 0 : ret; 10179875cf80SDavid Howells continue; 10189875cf80SDavid Howells } 10199875cf80SDavid Howells 10209875cf80SDavid Howells /* We didn't change the current path point */ 10219875cf80SDavid Howells break; 10229875cf80SDavid Howells } 10239875cf80SDavid Howells return 0; 10241da177e4SLinus Torvalds } 10251da177e4SLinus Torvalds 1026cc53ce53SDavid Howells int follow_down_one(struct path *path) 10271da177e4SLinus Torvalds { 10281da177e4SLinus Torvalds struct vfsmount *mounted; 10291da177e4SLinus Torvalds 10301c755af4SAl Viro mounted = lookup_mnt(path); 10311da177e4SLinus Torvalds if (mounted) { 10329393bd07SAl Viro dput(path->dentry); 10339393bd07SAl Viro mntput(path->mnt); 10349393bd07SAl Viro path->mnt = mounted; 10359393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10361da177e4SLinus Torvalds return 1; 10371da177e4SLinus Torvalds } 10381da177e4SLinus Torvalds return 0; 10391da177e4SLinus Torvalds } 10401da177e4SLinus Torvalds 10419875cf80SDavid Howells /* 10429875cf80SDavid Howells * Skip to top of mountpoint pile in rcuwalk mode. We abort the rcu-walk if we 1043cc53ce53SDavid Howells * meet a managed dentry and we're not walking to "..". True is returned to 10449875cf80SDavid Howells * continue, false to abort. 10459875cf80SDavid Howells */ 10469875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 10479875cf80SDavid Howells struct inode **inode, bool reverse_transit) 10489875cf80SDavid Howells { 1049cc53ce53SDavid Howells unsigned abort_mask = 1050cc53ce53SDavid Howells reverse_transit ? 0 : DCACHE_MANAGE_TRANSIT; 1051cc53ce53SDavid Howells 10529875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10539875cf80SDavid Howells struct vfsmount *mounted; 1054cc53ce53SDavid Howells if (path->dentry->d_flags & abort_mask) 1055cc53ce53SDavid Howells return true; 10569875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 10579875cf80SDavid Howells if (!mounted) 10589875cf80SDavid Howells break; 10599875cf80SDavid Howells path->mnt = mounted; 10609875cf80SDavid Howells path->dentry = mounted->mnt_root; 10619875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 10629875cf80SDavid Howells *inode = path->dentry->d_inode; 10639875cf80SDavid Howells } 10649875cf80SDavid Howells 10659875cf80SDavid Howells if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 10669875cf80SDavid Howells return reverse_transit; 10679875cf80SDavid Howells return true; 10689875cf80SDavid Howells } 10699875cf80SDavid Howells 107031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 107131e6b01fSNick Piggin { 107231e6b01fSNick Piggin struct inode *inode = nd->inode; 107331e6b01fSNick Piggin 107431e6b01fSNick Piggin set_root_rcu(nd); 107531e6b01fSNick Piggin 107631e6b01fSNick Piggin while (1) { 107731e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 107831e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 107931e6b01fSNick Piggin break; 108031e6b01fSNick Piggin } 108131e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 108231e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 108331e6b01fSNick Piggin struct dentry *parent = old->d_parent; 108431e6b01fSNick Piggin unsigned seq; 108531e6b01fSNick Piggin 108631e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 108731e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 108831e6b01fSNick Piggin return -ECHILD; 108931e6b01fSNick Piggin inode = parent->d_inode; 109031e6b01fSNick Piggin nd->path.dentry = parent; 109131e6b01fSNick Piggin nd->seq = seq; 109231e6b01fSNick Piggin break; 109331e6b01fSNick Piggin } 109431e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 109531e6b01fSNick Piggin break; 109631e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 109731e6b01fSNick Piggin inode = nd->path.dentry->d_inode; 109831e6b01fSNick Piggin } 10999875cf80SDavid Howells __follow_mount_rcu(nd, &nd->path, &inode, true); 110031e6b01fSNick Piggin nd->inode = inode; 110131e6b01fSNick Piggin 110231e6b01fSNick Piggin return 0; 110331e6b01fSNick Piggin } 110431e6b01fSNick Piggin 11059875cf80SDavid Howells /* 1106cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1107cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1108cc53ce53SDavid Howells * caller is permitted to proceed or not. 1109cc53ce53SDavid Howells * 1110cc53ce53SDavid Howells * Care must be taken as namespace_sem may be held (indicated by mounting_here 1111cc53ce53SDavid Howells * being true). 1112cc53ce53SDavid Howells */ 1113cc53ce53SDavid Howells int follow_down(struct path *path, bool mounting_here) 1114cc53ce53SDavid Howells { 1115cc53ce53SDavid Howells unsigned managed; 1116cc53ce53SDavid Howells int ret; 1117cc53ce53SDavid Howells 1118cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1119cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1120cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1121cc53ce53SDavid Howells * being held. 1122cc53ce53SDavid Howells * 1123cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1124cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1125cc53ce53SDavid Howells * other than its daemon the right to mount on its 1126cc53ce53SDavid Howells * superstructure. 1127cc53ce53SDavid Howells * 1128cc53ce53SDavid Howells * The filesystem may sleep at this point. 1129cc53ce53SDavid Howells */ 1130cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1131cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1132cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1133cc53ce53SDavid Howells ret = path->dentry->d_op->d_manage(path->dentry, mounting_here); 1134cc53ce53SDavid Howells if (ret < 0) 1135cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1136cc53ce53SDavid Howells } 1137cc53ce53SDavid Howells 1138cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1139cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1140cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1141cc53ce53SDavid Howells if (!mounted) 1142cc53ce53SDavid Howells break; 1143cc53ce53SDavid Howells dput(path->dentry); 1144cc53ce53SDavid Howells mntput(path->mnt); 1145cc53ce53SDavid Howells path->mnt = mounted; 1146cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1147cc53ce53SDavid Howells continue; 1148cc53ce53SDavid Howells } 1149cc53ce53SDavid Howells 1150cc53ce53SDavid Howells /* Don't handle automount points here */ 1151cc53ce53SDavid Howells break; 1152cc53ce53SDavid Howells } 1153cc53ce53SDavid Howells return 0; 1154cc53ce53SDavid Howells } 1155cc53ce53SDavid Howells 1156cc53ce53SDavid Howells /* 11579875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 11589875cf80SDavid Howells */ 11599875cf80SDavid Howells static void follow_mount(struct path *path) 11609875cf80SDavid Howells { 11619875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 11629875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11639875cf80SDavid Howells if (!mounted) 11649875cf80SDavid Howells break; 11659875cf80SDavid Howells dput(path->dentry); 11669875cf80SDavid Howells mntput(path->mnt); 11679875cf80SDavid Howells path->mnt = mounted; 11689875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 11699875cf80SDavid Howells } 11709875cf80SDavid Howells } 11719875cf80SDavid Howells 117231e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 11731da177e4SLinus Torvalds { 11742a737871SAl Viro set_root(nd); 1175e518ddb7SAndreas Mohr 11761da177e4SLinus Torvalds while(1) { 11774ac91378SJan Blunck struct dentry *old = nd->path.dentry; 11781da177e4SLinus Torvalds 11792a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 11802a737871SAl Viro nd->path.mnt == nd->root.mnt) { 11811da177e4SLinus Torvalds break; 11821da177e4SLinus Torvalds } 11834ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 11843088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 11853088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 11861da177e4SLinus Torvalds dput(old); 11871da177e4SLinus Torvalds break; 11881da177e4SLinus Torvalds } 11893088dd70SAl Viro if (!follow_up(&nd->path)) 11901da177e4SLinus Torvalds break; 11911da177e4SLinus Torvalds } 119279ed0226SAl Viro follow_mount(&nd->path); 119331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 11941da177e4SLinus Torvalds } 11951da177e4SLinus Torvalds 11961da177e4SLinus Torvalds /* 1197baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1198baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1199baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1200baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1201baa03890SNick Piggin */ 1202baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1203baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1204baa03890SNick Piggin { 1205baa03890SNick Piggin struct inode *inode = parent->d_inode; 1206baa03890SNick Piggin struct dentry *dentry; 1207baa03890SNick Piggin struct dentry *old; 1208baa03890SNick Piggin 1209baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1210baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1211baa03890SNick Piggin return ERR_PTR(-ENOENT); 1212baa03890SNick Piggin 1213baa03890SNick Piggin dentry = d_alloc(parent, name); 1214baa03890SNick Piggin if (unlikely(!dentry)) 1215baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1216baa03890SNick Piggin 1217baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1218baa03890SNick Piggin if (unlikely(old)) { 1219baa03890SNick Piggin dput(dentry); 1220baa03890SNick Piggin dentry = old; 1221baa03890SNick Piggin } 1222baa03890SNick Piggin return dentry; 1223baa03890SNick Piggin } 1224baa03890SNick Piggin 1225baa03890SNick Piggin /* 12261da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 12271da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 12281da177e4SLinus Torvalds * It _is_ time-critical. 12291da177e4SLinus Torvalds */ 12301da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 123131e6b01fSNick Piggin struct path *path, struct inode **inode) 12321da177e4SLinus Torvalds { 12334ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 123431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 12356e6b1bd1SAl Viro struct inode *dir; 12369875cf80SDavid Howells int err; 12379875cf80SDavid Howells 12383cac260aSAl Viro /* 12393cac260aSAl Viro * See if the low-level filesystem might want 12403cac260aSAl Viro * to use its own hash.. 12413cac260aSAl Viro */ 1242fb045adbSNick Piggin if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 12439875cf80SDavid Howells err = parent->d_op->d_hash(parent, nd->inode, name); 12443cac260aSAl Viro if (err < 0) 12453cac260aSAl Viro return err; 12463cac260aSAl Viro } 12471da177e4SLinus Torvalds 1248b04f784eSNick Piggin /* 1249b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1250b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1251b04f784eSNick Piggin * do the non-racy lookup, below. 1252b04f784eSNick Piggin */ 125331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 125431e6b01fSNick Piggin unsigned seq; 125531e6b01fSNick Piggin 125631e6b01fSNick Piggin *inode = nd->inode; 125731e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 125831e6b01fSNick Piggin if (!dentry) { 125931e6b01fSNick Piggin if (nameidata_drop_rcu(nd)) 126031e6b01fSNick Piggin return -ECHILD; 126131e6b01fSNick Piggin goto need_lookup; 126231e6b01fSNick Piggin } 126331e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 126431e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 126531e6b01fSNick Piggin return -ECHILD; 126631e6b01fSNick Piggin 126731e6b01fSNick Piggin nd->seq = seq; 126834286d66SNick Piggin if (dentry->d_flags & DCACHE_OP_REVALIDATE) 126931e6b01fSNick Piggin goto need_revalidate; 12701a8edf40SAl Viro done2: 127131e6b01fSNick Piggin path->mnt = mnt; 127231e6b01fSNick Piggin path->dentry = dentry; 12739875cf80SDavid Howells if (likely(__follow_mount_rcu(nd, path, inode, false))) 12749875cf80SDavid Howells return 0; 12759875cf80SDavid Howells if (nameidata_drop_rcu(nd)) 12769875cf80SDavid Howells return -ECHILD; 12779875cf80SDavid Howells /* fallthru */ 12789875cf80SDavid Howells } 127931e6b01fSNick Piggin dentry = __d_lookup(parent, name); 12801da177e4SLinus Torvalds if (!dentry) 12811da177e4SLinus Torvalds goto need_lookup; 12822e2e88eaSNick Piggin found: 1283fb045adbSNick Piggin if (dentry->d_flags & DCACHE_OP_REVALIDATE) 12841da177e4SLinus Torvalds goto need_revalidate; 12851da177e4SLinus Torvalds done: 12861da177e4SLinus Torvalds path->mnt = mnt; 12871da177e4SLinus Torvalds path->dentry = dentry; 12889875cf80SDavid Howells err = follow_managed(path, nd->flags); 12899875cf80SDavid Howells if (unlikely(err < 0)) 12909875cf80SDavid Howells return err; 129131e6b01fSNick Piggin *inode = path->dentry->d_inode; 12921da177e4SLinus Torvalds return 0; 12931da177e4SLinus Torvalds 12941da177e4SLinus Torvalds need_lookup: 12956e6b1bd1SAl Viro dir = parent->d_inode; 129631e6b01fSNick Piggin BUG_ON(nd->inode != dir); 12976e6b1bd1SAl Viro 12986e6b1bd1SAl Viro mutex_lock(&dir->i_mutex); 12996e6b1bd1SAl Viro /* 13006e6b1bd1SAl Viro * First re-do the cached lookup just in case it was created 1301b04f784eSNick Piggin * while we waited for the directory semaphore, or the first 1302b04f784eSNick Piggin * lookup failed due to an unrelated rename. 13036e6b1bd1SAl Viro * 1304b04f784eSNick Piggin * This could use version numbering or similar to avoid unnecessary 1305b04f784eSNick Piggin * cache lookups, but then we'd have to do the first lookup in the 1306b04f784eSNick Piggin * non-racy way. However in the common case here, everything should 1307b04f784eSNick Piggin * be hot in cache, so would it be a big win? 13086e6b1bd1SAl Viro */ 13096e6b1bd1SAl Viro dentry = d_lookup(parent, name); 1310baa03890SNick Piggin if (likely(!dentry)) { 1311baa03890SNick Piggin dentry = d_alloc_and_lookup(parent, name, nd); 13126e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 13136e6b1bd1SAl Viro if (IS_ERR(dentry)) 13146e6b1bd1SAl Viro goto fail; 13156e6b1bd1SAl Viro goto done; 13166e6b1bd1SAl Viro } 13176e6b1bd1SAl Viro /* 13186e6b1bd1SAl Viro * Uhhuh! Nasty case: the cache was re-populated while 13196e6b1bd1SAl Viro * we waited on the semaphore. Need to revalidate. 13206e6b1bd1SAl Viro */ 13216e6b1bd1SAl Viro mutex_unlock(&dir->i_mutex); 13222e2e88eaSNick Piggin goto found; 13231da177e4SLinus Torvalds 13241da177e4SLinus Torvalds need_revalidate: 1325bcdc5e01SIan Kent dentry = do_revalidate(dentry, nd); 1326bcdc5e01SIan Kent if (!dentry) 13271da177e4SLinus Torvalds goto need_lookup; 1328bcdc5e01SIan Kent if (IS_ERR(dentry)) 1329bcdc5e01SIan Kent goto fail; 13301a8edf40SAl Viro if (nd->flags & LOOKUP_RCU) 13311a8edf40SAl Viro goto done2; 1332bcdc5e01SIan Kent goto done; 13331da177e4SLinus Torvalds 13341da177e4SLinus Torvalds fail: 13351da177e4SLinus Torvalds return PTR_ERR(dentry); 13361da177e4SLinus Torvalds } 13371da177e4SLinus Torvalds 13381da177e4SLinus Torvalds /* 1339ac278a9cSAl Viro * This is a temporary kludge to deal with "automount" symlinks; proper 1340ac278a9cSAl Viro * solution is to trigger them on follow_mount(), so that do_lookup() 1341ac278a9cSAl Viro * would DTRT. To be killed before 2.6.34-final. 1342ac278a9cSAl Viro */ 1343ac278a9cSAl Viro static inline int follow_on_final(struct inode *inode, unsigned lookup_flags) 1344ac278a9cSAl Viro { 1345ac278a9cSAl Viro return inode && unlikely(inode->i_op->follow_link) && 1346ac278a9cSAl Viro ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode)); 1347ac278a9cSAl Viro } 1348ac278a9cSAl Viro 1349ac278a9cSAl Viro /* 13501da177e4SLinus Torvalds * Name resolution. 1351ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1352ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13531da177e4SLinus Torvalds * 1354ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1355ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13561da177e4SLinus Torvalds */ 13576de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13581da177e4SLinus Torvalds { 13591da177e4SLinus Torvalds struct path next; 13601da177e4SLinus Torvalds int err; 13611da177e4SLinus Torvalds unsigned int lookup_flags = nd->flags; 13621da177e4SLinus Torvalds 13631da177e4SLinus Torvalds while (*name=='/') 13641da177e4SLinus Torvalds name++; 13651da177e4SLinus Torvalds if (!*name) 13661da177e4SLinus Torvalds goto return_reval; 13671da177e4SLinus Torvalds 13681da177e4SLinus Torvalds if (nd->depth) 1369f55eab82STrond Myklebust lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); 13701da177e4SLinus Torvalds 13711da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13721da177e4SLinus Torvalds for(;;) { 137331e6b01fSNick Piggin struct inode *inode; 13741da177e4SLinus Torvalds unsigned long hash; 13751da177e4SLinus Torvalds struct qstr this; 13761da177e4SLinus Torvalds unsigned int c; 13771da177e4SLinus Torvalds 1378cdce5d6bSTrond Myklebust nd->flags |= LOOKUP_CONTINUE; 137931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 1380b74c79e9SNick Piggin err = exec_permission(nd->inode, IPERM_FLAG_RCU); 138131e6b01fSNick Piggin if (err == -ECHILD) { 138231e6b01fSNick Piggin if (nameidata_drop_rcu(nd)) 138331e6b01fSNick Piggin return -ECHILD; 138431e6b01fSNick Piggin goto exec_again; 138531e6b01fSNick Piggin } 138631e6b01fSNick Piggin } else { 138731e6b01fSNick Piggin exec_again: 1388b74c79e9SNick Piggin err = exec_permission(nd->inode, 0); 138931e6b01fSNick Piggin } 13901da177e4SLinus Torvalds if (err) 13911da177e4SLinus Torvalds break; 13921da177e4SLinus Torvalds 13931da177e4SLinus Torvalds this.name = name; 13941da177e4SLinus Torvalds c = *(const unsigned char *)name; 13951da177e4SLinus Torvalds 13961da177e4SLinus Torvalds hash = init_name_hash(); 13971da177e4SLinus Torvalds do { 13981da177e4SLinus Torvalds name++; 13991da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 14001da177e4SLinus Torvalds c = *(const unsigned char *)name; 14011da177e4SLinus Torvalds } while (c && (c != '/')); 14021da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14031da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14041da177e4SLinus Torvalds 14051da177e4SLinus Torvalds /* remove trailing slashes? */ 14061da177e4SLinus Torvalds if (!c) 14071da177e4SLinus Torvalds goto last_component; 14081da177e4SLinus Torvalds while (*++name == '/'); 14091da177e4SLinus Torvalds if (!*name) 14101da177e4SLinus Torvalds goto last_with_slashes; 14111da177e4SLinus Torvalds 14121da177e4SLinus Torvalds /* 14131da177e4SLinus Torvalds * "." and ".." are special - ".." especially so because it has 14141da177e4SLinus Torvalds * to be able to know about the current root directory and 14151da177e4SLinus Torvalds * parent relationships. 14161da177e4SLinus Torvalds */ 14171da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 14181da177e4SLinus Torvalds default: 14191da177e4SLinus Torvalds break; 14201da177e4SLinus Torvalds case 2: 14211da177e4SLinus Torvalds if (this.name[1] != '.') 14221da177e4SLinus Torvalds break; 142331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 142431e6b01fSNick Piggin if (follow_dotdot_rcu(nd)) 142531e6b01fSNick Piggin return -ECHILD; 142631e6b01fSNick Piggin } else 142758c465ebSAl Viro follow_dotdot(nd); 14281da177e4SLinus Torvalds /* fallthrough */ 14291da177e4SLinus Torvalds case 1: 14301da177e4SLinus Torvalds continue; 14311da177e4SLinus Torvalds } 14321da177e4SLinus Torvalds /* This does the actual lookups.. */ 143331e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 14341da177e4SLinus Torvalds if (err) 14351da177e4SLinus Torvalds break; 14361da177e4SLinus Torvalds err = -ENOENT; 14371da177e4SLinus Torvalds if (!inode) 14381da177e4SLinus Torvalds goto out_dput; 14391da177e4SLinus Torvalds 14401da177e4SLinus Torvalds if (inode->i_op->follow_link) { 144131e6b01fSNick Piggin /* We commonly drop rcu-walk here */ 144231e6b01fSNick Piggin if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry)) 144331e6b01fSNick Piggin return -ECHILD; 144431e6b01fSNick Piggin BUG_ON(inode != next.dentry->d_inode); 144590ebe565SAl Viro err = do_follow_link(&next, nd); 14461da177e4SLinus Torvalds if (err) 14471da177e4SLinus Torvalds goto return_err; 144831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 14491da177e4SLinus Torvalds err = -ENOENT; 145031e6b01fSNick Piggin if (!nd->inode) 14511da177e4SLinus Torvalds break; 145231e6b01fSNick Piggin } else { 145309dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 145431e6b01fSNick Piggin nd->inode = inode; 145531e6b01fSNick Piggin } 14561da177e4SLinus Torvalds err = -ENOTDIR; 145731e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 14581da177e4SLinus Torvalds break; 14591da177e4SLinus Torvalds continue; 14601da177e4SLinus Torvalds /* here ends the main loop */ 14611da177e4SLinus Torvalds 14621da177e4SLinus Torvalds last_with_slashes: 14631da177e4SLinus Torvalds lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 14641da177e4SLinus Torvalds last_component: 1465f55eab82STrond Myklebust /* Clear LOOKUP_CONTINUE iff it was previously unset */ 1466f55eab82STrond Myklebust nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; 14671da177e4SLinus Torvalds if (lookup_flags & LOOKUP_PARENT) 14681da177e4SLinus Torvalds goto lookup_parent; 14691da177e4SLinus Torvalds if (this.name[0] == '.') switch (this.len) { 14701da177e4SLinus Torvalds default: 14711da177e4SLinus Torvalds break; 14721da177e4SLinus Torvalds case 2: 14731da177e4SLinus Torvalds if (this.name[1] != '.') 14741da177e4SLinus Torvalds break; 147531e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 147631e6b01fSNick Piggin if (follow_dotdot_rcu(nd)) 147731e6b01fSNick Piggin return -ECHILD; 147831e6b01fSNick Piggin } else 147958c465ebSAl Viro follow_dotdot(nd); 14801da177e4SLinus Torvalds /* fallthrough */ 14811da177e4SLinus Torvalds case 1: 14821da177e4SLinus Torvalds goto return_reval; 14831da177e4SLinus Torvalds } 148431e6b01fSNick Piggin err = do_lookup(nd, &this, &next, &inode); 14851da177e4SLinus Torvalds if (err) 14861da177e4SLinus Torvalds break; 1487ac278a9cSAl Viro if (follow_on_final(inode, lookup_flags)) { 148831e6b01fSNick Piggin if (nameidata_dentry_drop_rcu_maybe(nd, next.dentry)) 148931e6b01fSNick Piggin return -ECHILD; 149031e6b01fSNick Piggin BUG_ON(inode != next.dentry->d_inode); 149190ebe565SAl Viro err = do_follow_link(&next, nd); 14921da177e4SLinus Torvalds if (err) 14931da177e4SLinus Torvalds goto return_err; 149431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 149531e6b01fSNick Piggin } else { 149609dd17d3SMiklos Szeredi path_to_nameidata(&next, nd); 149731e6b01fSNick Piggin nd->inode = inode; 149831e6b01fSNick Piggin } 14991da177e4SLinus Torvalds err = -ENOENT; 150031e6b01fSNick Piggin if (!nd->inode) 15011da177e4SLinus Torvalds break; 15021da177e4SLinus Torvalds if (lookup_flags & LOOKUP_DIRECTORY) { 15031da177e4SLinus Torvalds err = -ENOTDIR; 150431e6b01fSNick Piggin if (!nd->inode->i_op->lookup) 15051da177e4SLinus Torvalds break; 15061da177e4SLinus Torvalds } 15071da177e4SLinus Torvalds goto return_base; 15081da177e4SLinus Torvalds lookup_parent: 15091da177e4SLinus Torvalds nd->last = this; 15101da177e4SLinus Torvalds nd->last_type = LAST_NORM; 15111da177e4SLinus Torvalds if (this.name[0] != '.') 15121da177e4SLinus Torvalds goto return_base; 15131da177e4SLinus Torvalds if (this.len == 1) 15141da177e4SLinus Torvalds nd->last_type = LAST_DOT; 15151da177e4SLinus Torvalds else if (this.len == 2 && this.name[1] == '.') 15161da177e4SLinus Torvalds nd->last_type = LAST_DOTDOT; 15171da177e4SLinus Torvalds else 15181da177e4SLinus Torvalds goto return_base; 15191da177e4SLinus Torvalds return_reval: 15201da177e4SLinus Torvalds /* 15211da177e4SLinus Torvalds * We bypassed the ordinary revalidation routines. 15221da177e4SLinus Torvalds * We may need to check the cached dentry for staleness. 15231da177e4SLinus Torvalds */ 1524fb045adbSNick Piggin if (need_reval_dot(nd->path.dentry)) { 15251da177e4SLinus Torvalds /* Note: we do not d_invalidate() */ 152634286d66SNick Piggin err = d_revalidate(nd->path.dentry, nd); 152734286d66SNick Piggin if (!err) 152834286d66SNick Piggin err = -ESTALE; 152934286d66SNick Piggin if (err < 0) 15301da177e4SLinus Torvalds break; 15311da177e4SLinus Torvalds } 15321da177e4SLinus Torvalds return_base: 153331e6b01fSNick Piggin if (nameidata_drop_rcu_last_maybe(nd)) 153431e6b01fSNick Piggin return -ECHILD; 15351da177e4SLinus Torvalds return 0; 15361da177e4SLinus Torvalds out_dput: 153731e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) 15381d957f9bSJan Blunck path_put_conditional(&next, nd); 15391da177e4SLinus Torvalds break; 15401da177e4SLinus Torvalds } 154131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) 15421d957f9bSJan Blunck path_put(&nd->path); 15431da177e4SLinus Torvalds return_err: 15441da177e4SLinus Torvalds return err; 15451da177e4SLinus Torvalds } 15461da177e4SLinus Torvalds 154731e6b01fSNick Piggin static inline int path_walk_rcu(const char *name, struct nameidata *nd) 154831e6b01fSNick Piggin { 154931e6b01fSNick Piggin current->total_link_count = 0; 155031e6b01fSNick Piggin 155131e6b01fSNick Piggin return link_path_walk(name, nd); 155231e6b01fSNick Piggin } 155331e6b01fSNick Piggin 155431e6b01fSNick Piggin static inline int path_walk_simple(const char *name, struct nameidata *nd) 155531e6b01fSNick Piggin { 155631e6b01fSNick Piggin current->total_link_count = 0; 155731e6b01fSNick Piggin 155831e6b01fSNick Piggin return link_path_walk(name, nd); 155931e6b01fSNick Piggin } 156031e6b01fSNick Piggin 1561fc9b52cdSHarvey Harrison static int path_walk(const char *name, struct nameidata *nd) 15621da177e4SLinus Torvalds { 15636de88d72SAl Viro struct path save = nd->path; 15646de88d72SAl Viro int result; 15656de88d72SAl Viro 15661da177e4SLinus Torvalds current->total_link_count = 0; 15676de88d72SAl Viro 15686de88d72SAl Viro /* make sure the stuff we saved doesn't go away */ 15696de88d72SAl Viro path_get(&save); 15706de88d72SAl Viro 15716de88d72SAl Viro result = link_path_walk(name, nd); 15726de88d72SAl Viro if (result == -ESTALE) { 15736de88d72SAl Viro /* nd->path had been dropped */ 15746de88d72SAl Viro current->total_link_count = 0; 15756de88d72SAl Viro nd->path = save; 15766de88d72SAl Viro path_get(&nd->path); 15776de88d72SAl Viro nd->flags |= LOOKUP_REVAL; 15786de88d72SAl Viro result = link_path_walk(name, nd); 15796de88d72SAl Viro } 15806de88d72SAl Viro 15816de88d72SAl Viro path_put(&save); 15826de88d72SAl Viro 15836de88d72SAl Viro return result; 15841da177e4SLinus Torvalds } 15851da177e4SLinus Torvalds 158631e6b01fSNick Piggin static void path_finish_rcu(struct nameidata *nd) 158731e6b01fSNick Piggin { 158831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 158931e6b01fSNick Piggin /* RCU dangling. Cancel it. */ 159031e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 159131e6b01fSNick Piggin nd->root.mnt = NULL; 159231e6b01fSNick Piggin rcu_read_unlock(); 159331e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 159431e6b01fSNick Piggin } 159531e6b01fSNick Piggin if (nd->file) 159631e6b01fSNick Piggin fput(nd->file); 159731e6b01fSNick Piggin } 159831e6b01fSNick Piggin 159931e6b01fSNick Piggin static int path_init_rcu(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 160031e6b01fSNick Piggin { 160131e6b01fSNick Piggin int retval = 0; 160231e6b01fSNick Piggin int fput_needed; 160331e6b01fSNick Piggin struct file *file; 160431e6b01fSNick Piggin 160531e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 160631e6b01fSNick Piggin nd->flags = flags | LOOKUP_RCU; 160731e6b01fSNick Piggin nd->depth = 0; 160831e6b01fSNick Piggin nd->root.mnt = NULL; 160931e6b01fSNick Piggin nd->file = NULL; 161031e6b01fSNick Piggin 161131e6b01fSNick Piggin if (*name=='/') { 161231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1613c28cc364SNick Piggin unsigned seq; 161431e6b01fSNick Piggin 161531e6b01fSNick Piggin br_read_lock(vfsmount_lock); 161631e6b01fSNick Piggin rcu_read_lock(); 161731e6b01fSNick Piggin 1618c28cc364SNick Piggin do { 1619c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 162031e6b01fSNick Piggin nd->root = fs->root; 162131e6b01fSNick Piggin nd->path = nd->root; 1622c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1623c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 162431e6b01fSNick Piggin 162531e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 162631e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1627c28cc364SNick Piggin unsigned seq; 162831e6b01fSNick Piggin 162931e6b01fSNick Piggin br_read_lock(vfsmount_lock); 163031e6b01fSNick Piggin rcu_read_lock(); 163131e6b01fSNick Piggin 1632c28cc364SNick Piggin do { 1633c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 163431e6b01fSNick Piggin nd->path = fs->pwd; 1635c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1636c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1637c28cc364SNick Piggin 163831e6b01fSNick Piggin } else { 163931e6b01fSNick Piggin struct dentry *dentry; 164031e6b01fSNick Piggin 164131e6b01fSNick Piggin file = fget_light(dfd, &fput_needed); 164231e6b01fSNick Piggin retval = -EBADF; 164331e6b01fSNick Piggin if (!file) 164431e6b01fSNick Piggin goto out_fail; 164531e6b01fSNick Piggin 164631e6b01fSNick Piggin dentry = file->f_path.dentry; 164731e6b01fSNick Piggin 164831e6b01fSNick Piggin retval = -ENOTDIR; 164931e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 165031e6b01fSNick Piggin goto fput_fail; 165131e6b01fSNick Piggin 165231e6b01fSNick Piggin retval = file_permission(file, MAY_EXEC); 165331e6b01fSNick Piggin if (retval) 165431e6b01fSNick Piggin goto fput_fail; 165531e6b01fSNick Piggin 165631e6b01fSNick Piggin nd->path = file->f_path; 165731e6b01fSNick Piggin if (fput_needed) 165831e6b01fSNick Piggin nd->file = file; 165931e6b01fSNick Piggin 1660c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 166131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 166231e6b01fSNick Piggin rcu_read_lock(); 166331e6b01fSNick Piggin } 166431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 166531e6b01fSNick Piggin return 0; 166631e6b01fSNick Piggin 166731e6b01fSNick Piggin fput_fail: 166831e6b01fSNick Piggin fput_light(file, fput_needed); 166931e6b01fSNick Piggin out_fail: 167031e6b01fSNick Piggin return retval; 167131e6b01fSNick Piggin } 167231e6b01fSNick Piggin 16739b4a9b14SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) 16741da177e4SLinus Torvalds { 1675ea3834d9SPrasanna Meda int retval = 0; 1676170aa3d0SUlrich Drepper int fput_needed; 1677170aa3d0SUlrich Drepper struct file *file; 16781da177e4SLinus Torvalds 16791da177e4SLinus Torvalds nd->last_type = LAST_ROOT; /* if there are only slashes... */ 16801da177e4SLinus Torvalds nd->flags = flags; 16811da177e4SLinus Torvalds nd->depth = 0; 16822a737871SAl Viro nd->root.mnt = NULL; 16831da177e4SLinus Torvalds 16841da177e4SLinus Torvalds if (*name=='/') { 16852a737871SAl Viro set_root(nd); 16862a737871SAl Viro nd->path = nd->root; 16872a737871SAl Viro path_get(&nd->root); 16885590ff0dSUlrich Drepper } else if (dfd == AT_FDCWD) { 1689f7ad3c6bSMiklos Szeredi get_fs_pwd(current->fs, &nd->path); 16905590ff0dSUlrich Drepper } else { 16915590ff0dSUlrich Drepper struct dentry *dentry; 16925590ff0dSUlrich Drepper 16935590ff0dSUlrich Drepper file = fget_light(dfd, &fput_needed); 16945590ff0dSUlrich Drepper retval = -EBADF; 1695170aa3d0SUlrich Drepper if (!file) 16966d09bb62STrond Myklebust goto out_fail; 16975590ff0dSUlrich Drepper 16980f7fc9e4SJosef "Jeff" Sipek dentry = file->f_path.dentry; 16995590ff0dSUlrich Drepper 17005590ff0dSUlrich Drepper retval = -ENOTDIR; 1701170aa3d0SUlrich Drepper if (!S_ISDIR(dentry->d_inode->i_mode)) 17026d09bb62STrond Myklebust goto fput_fail; 17035590ff0dSUlrich Drepper 17045590ff0dSUlrich Drepper retval = file_permission(file, MAY_EXEC); 1705170aa3d0SUlrich Drepper if (retval) 17066d09bb62STrond Myklebust goto fput_fail; 17075590ff0dSUlrich Drepper 17085dd784d0SJan Blunck nd->path = file->f_path; 17095dd784d0SJan Blunck path_get(&file->f_path); 17105590ff0dSUlrich Drepper 17115590ff0dSUlrich Drepper fput_light(file, fput_needed); 17121da177e4SLinus Torvalds } 171331e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17149b4a9b14SAl Viro return 0; 17152dfdd266SJosef 'Jeff' Sipek 17169b4a9b14SAl Viro fput_fail: 17179b4a9b14SAl Viro fput_light(file, fput_needed); 17189b4a9b14SAl Viro out_fail: 17199b4a9b14SAl Viro return retval; 17209b4a9b14SAl Viro } 17219b4a9b14SAl Viro 17229b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 17239b4a9b14SAl Viro static int do_path_lookup(int dfd, const char *name, 17249b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17259b4a9b14SAl Viro { 172631e6b01fSNick Piggin int retval; 172731e6b01fSNick Piggin 172831e6b01fSNick Piggin /* 172931e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 173031e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 173131e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 173231e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 173331e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 173431e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 173531e6b01fSNick Piggin * analogue, foo_rcu(). 173631e6b01fSNick Piggin * 173731e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 173831e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 173931e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 174031e6b01fSNick Piggin * be able to complete). 174131e6b01fSNick Piggin */ 174231e6b01fSNick Piggin retval = path_init_rcu(dfd, name, flags, nd); 174331e6b01fSNick Piggin if (unlikely(retval)) 174431e6b01fSNick Piggin return retval; 174531e6b01fSNick Piggin retval = path_walk_rcu(name, nd); 174631e6b01fSNick Piggin path_finish_rcu(nd); 17472a737871SAl Viro if (nd->root.mnt) { 17482a737871SAl Viro path_put(&nd->root); 17492a737871SAl Viro nd->root.mnt = NULL; 17502a737871SAl Viro } 175131e6b01fSNick Piggin 175231e6b01fSNick Piggin if (unlikely(retval == -ECHILD || retval == -ESTALE)) { 175331e6b01fSNick Piggin /* slower, locked walk */ 175431e6b01fSNick Piggin if (retval == -ESTALE) 175531e6b01fSNick Piggin flags |= LOOKUP_REVAL; 175631e6b01fSNick Piggin retval = path_init(dfd, name, flags, nd); 175731e6b01fSNick Piggin if (unlikely(retval)) 175831e6b01fSNick Piggin return retval; 175931e6b01fSNick Piggin retval = path_walk(name, nd); 176031e6b01fSNick Piggin if (nd->root.mnt) { 176131e6b01fSNick Piggin path_put(&nd->root); 176231e6b01fSNick Piggin nd->root.mnt = NULL; 176331e6b01fSNick Piggin } 176431e6b01fSNick Piggin } 176531e6b01fSNick Piggin 176631e6b01fSNick Piggin if (likely(!retval)) { 176731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 176831e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 176931e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 177031e6b01fSNick Piggin } 177131e6b01fSNick Piggin } 177231e6b01fSNick Piggin 1773170aa3d0SUlrich Drepper return retval; 17741da177e4SLinus Torvalds } 17751da177e4SLinus Torvalds 1776fc9b52cdSHarvey Harrison int path_lookup(const char *name, unsigned int flags, 17775590ff0dSUlrich Drepper struct nameidata *nd) 17785590ff0dSUlrich Drepper { 17795590ff0dSUlrich Drepper return do_path_lookup(AT_FDCWD, name, flags, nd); 17805590ff0dSUlrich Drepper } 17815590ff0dSUlrich Drepper 1782d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1783d1811465SAl Viro { 1784d1811465SAl Viro struct nameidata nd; 1785d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1786d1811465SAl Viro if (!res) 1787d1811465SAl Viro *path = nd.path; 1788d1811465SAl Viro return res; 1789d1811465SAl Viro } 1790d1811465SAl Viro 179116f18200SJosef 'Jeff' Sipek /** 179216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 179316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 179416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 179516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 179616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 179716f18200SJosef 'Jeff' Sipek * @nd: pointer to nameidata 179816f18200SJosef 'Jeff' Sipek */ 179916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 180016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 180116f18200SJosef 'Jeff' Sipek struct nameidata *nd) 180216f18200SJosef 'Jeff' Sipek { 180316f18200SJosef 'Jeff' Sipek int retval; 180416f18200SJosef 'Jeff' Sipek 180516f18200SJosef 'Jeff' Sipek /* same as do_path_lookup */ 180616f18200SJosef 'Jeff' Sipek nd->last_type = LAST_ROOT; 180716f18200SJosef 'Jeff' Sipek nd->flags = flags; 180816f18200SJosef 'Jeff' Sipek nd->depth = 0; 180916f18200SJosef 'Jeff' Sipek 1810c8e7f449SJan Blunck nd->path.dentry = dentry; 1811c8e7f449SJan Blunck nd->path.mnt = mnt; 1812c8e7f449SJan Blunck path_get(&nd->path); 18135b857119SAl Viro nd->root = nd->path; 18145b857119SAl Viro path_get(&nd->root); 181531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 181616f18200SJosef 'Jeff' Sipek 181716f18200SJosef 'Jeff' Sipek retval = path_walk(name, nd); 18184ac91378SJan Blunck if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && 181931e6b01fSNick Piggin nd->inode)) 18204ac91378SJan Blunck audit_inode(name, nd->path.dentry); 182116f18200SJosef 'Jeff' Sipek 18222a737871SAl Viro path_put(&nd->root); 18232a737871SAl Viro nd->root.mnt = NULL; 182416f18200SJosef 'Jeff' Sipek 18252a737871SAl Viro return retval; 182616f18200SJosef 'Jeff' Sipek } 182716f18200SJosef 'Jeff' Sipek 1828eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1829eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 18301da177e4SLinus Torvalds { 183181fca444SChristoph Hellwig struct inode *inode = base->d_inode; 18321da177e4SLinus Torvalds struct dentry *dentry; 18331da177e4SLinus Torvalds int err; 18341da177e4SLinus Torvalds 1835b74c79e9SNick Piggin err = exec_permission(inode, 0); 183681fca444SChristoph Hellwig if (err) 183781fca444SChristoph Hellwig return ERR_PTR(err); 18381da177e4SLinus Torvalds 18391da177e4SLinus Torvalds /* 18401da177e4SLinus Torvalds * See if the low-level filesystem might want 18411da177e4SLinus Torvalds * to use its own hash.. 18421da177e4SLinus Torvalds */ 1843fb045adbSNick Piggin if (base->d_flags & DCACHE_OP_HASH) { 1844b1e6a015SNick Piggin err = base->d_op->d_hash(base, inode, name); 18451da177e4SLinus Torvalds dentry = ERR_PTR(err); 18461da177e4SLinus Torvalds if (err < 0) 18471da177e4SLinus Torvalds goto out; 18481da177e4SLinus Torvalds } 18491da177e4SLinus Torvalds 1850b04f784eSNick Piggin /* 1851b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1852b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1853b04f784eSNick Piggin * a double lookup. 18546e6b1bd1SAl Viro */ 18556e6b1bd1SAl Viro dentry = d_lookup(base, name); 18566e6b1bd1SAl Viro 1857fb045adbSNick Piggin if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) 18586e6b1bd1SAl Viro dentry = do_revalidate(dentry, nd); 18596e6b1bd1SAl Viro 18601da177e4SLinus Torvalds if (!dentry) 1861baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 18621da177e4SLinus Torvalds out: 18631da177e4SLinus Torvalds return dentry; 18641da177e4SLinus Torvalds } 18651da177e4SLinus Torvalds 1866057f6c01SJames Morris /* 1867057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1868057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1869057f6c01SJames Morris * SMP-safe. 1870057f6c01SJames Morris */ 1871a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 18721da177e4SLinus Torvalds { 18734ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 18741da177e4SLinus Torvalds } 18751da177e4SLinus Torvalds 1876eead1911SChristoph Hellwig static int __lookup_one_len(const char *name, struct qstr *this, 1877eead1911SChristoph Hellwig struct dentry *base, int len) 18781da177e4SLinus Torvalds { 18791da177e4SLinus Torvalds unsigned long hash; 18801da177e4SLinus Torvalds unsigned int c; 18811da177e4SLinus Torvalds 1882057f6c01SJames Morris this->name = name; 1883057f6c01SJames Morris this->len = len; 18841da177e4SLinus Torvalds if (!len) 1885057f6c01SJames Morris return -EACCES; 18861da177e4SLinus Torvalds 18871da177e4SLinus Torvalds hash = init_name_hash(); 18881da177e4SLinus Torvalds while (len--) { 18891da177e4SLinus Torvalds c = *(const unsigned char *)name++; 18901da177e4SLinus Torvalds if (c == '/' || c == '\0') 1891057f6c01SJames Morris return -EACCES; 18921da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 18931da177e4SLinus Torvalds } 1894057f6c01SJames Morris this->hash = end_name_hash(hash); 1895057f6c01SJames Morris return 0; 1896057f6c01SJames Morris } 18971da177e4SLinus Torvalds 1898eead1911SChristoph Hellwig /** 1899a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1900eead1911SChristoph Hellwig * @name: pathname component to lookup 1901eead1911SChristoph Hellwig * @base: base directory to lookup from 1902eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1903eead1911SChristoph Hellwig * 1904a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1905a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1906eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1907eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1908eead1911SChristoph Hellwig */ 1909057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1910057f6c01SJames Morris { 1911057f6c01SJames Morris int err; 1912057f6c01SJames Morris struct qstr this; 1913057f6c01SJames Morris 19142f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 19152f9092e1SDavid Woodhouse 1916057f6c01SJames Morris err = __lookup_one_len(name, &this, base, len); 1917057f6c01SJames Morris if (err) 1918057f6c01SJames Morris return ERR_PTR(err); 1919eead1911SChristoph Hellwig 192049705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1921057f6c01SJames Morris } 1922057f6c01SJames Morris 19232d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 19242d8f3038SAl Viro struct path *path) 19251da177e4SLinus Torvalds { 19262d8f3038SAl Viro struct nameidata nd; 19271da177e4SLinus Torvalds char *tmp = getname(name); 19281da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19291da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19302d8f3038SAl Viro 19312d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19322d8f3038SAl Viro 19332d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19341da177e4SLinus Torvalds putname(tmp); 19352d8f3038SAl Viro if (!err) 19362d8f3038SAl Viro *path = nd.path; 19371da177e4SLinus Torvalds } 19381da177e4SLinus Torvalds return err; 19391da177e4SLinus Torvalds } 19401da177e4SLinus Torvalds 19412ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 19422ad94ae6SAl Viro struct nameidata *nd, char **name) 19432ad94ae6SAl Viro { 19442ad94ae6SAl Viro char *s = getname(path); 19452ad94ae6SAl Viro int error; 19462ad94ae6SAl Viro 19472ad94ae6SAl Viro if (IS_ERR(s)) 19482ad94ae6SAl Viro return PTR_ERR(s); 19492ad94ae6SAl Viro 19502ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 19512ad94ae6SAl Viro if (error) 19522ad94ae6SAl Viro putname(s); 19532ad94ae6SAl Viro else 19542ad94ae6SAl Viro *name = s; 19552ad94ae6SAl Viro 19562ad94ae6SAl Viro return error; 19572ad94ae6SAl Viro } 19582ad94ae6SAl Viro 19591da177e4SLinus Torvalds /* 19601da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 19611da177e4SLinus Torvalds * minimal. 19621da177e4SLinus Torvalds */ 19631da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 19641da177e4SLinus Torvalds { 1965da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1966da9592edSDavid Howells 19671da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 19681da177e4SLinus Torvalds return 0; 1969da9592edSDavid Howells if (inode->i_uid == fsuid) 19701da177e4SLinus Torvalds return 0; 1971da9592edSDavid Howells if (dir->i_uid == fsuid) 19721da177e4SLinus Torvalds return 0; 19731da177e4SLinus Torvalds return !capable(CAP_FOWNER); 19741da177e4SLinus Torvalds } 19751da177e4SLinus Torvalds 19761da177e4SLinus Torvalds /* 19771da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 19781da177e4SLinus Torvalds * whether the type of victim is right. 19791da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 19801da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 19811da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 19821da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 19831da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 19841da177e4SLinus Torvalds * a. be owner of dir, or 19851da177e4SLinus Torvalds * b. be owner of victim, or 19861da177e4SLinus Torvalds * c. have CAP_FOWNER capability 19871da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 19881da177e4SLinus Torvalds * links pointing to it. 19891da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 19901da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 19911da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 19921da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 19931da177e4SLinus Torvalds * nfs_async_unlink(). 19941da177e4SLinus Torvalds */ 1995858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 19961da177e4SLinus Torvalds { 19971da177e4SLinus Torvalds int error; 19981da177e4SLinus Torvalds 19991da177e4SLinus Torvalds if (!victim->d_inode) 20001da177e4SLinus Torvalds return -ENOENT; 20011da177e4SLinus Torvalds 20021da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2003cccc6bbaSAl Viro audit_inode_child(victim, dir); 20041da177e4SLinus Torvalds 2005f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20061da177e4SLinus Torvalds if (error) 20071da177e4SLinus Torvalds return error; 20081da177e4SLinus Torvalds if (IS_APPEND(dir)) 20091da177e4SLinus Torvalds return -EPERM; 20101da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2011f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20121da177e4SLinus Torvalds return -EPERM; 20131da177e4SLinus Torvalds if (isdir) { 20141da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20151da177e4SLinus Torvalds return -ENOTDIR; 20161da177e4SLinus Torvalds if (IS_ROOT(victim)) 20171da177e4SLinus Torvalds return -EBUSY; 20181da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20191da177e4SLinus Torvalds return -EISDIR; 20201da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20211da177e4SLinus Torvalds return -ENOENT; 20221da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20231da177e4SLinus Torvalds return -EBUSY; 20241da177e4SLinus Torvalds return 0; 20251da177e4SLinus Torvalds } 20261da177e4SLinus Torvalds 20271da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20281da177e4SLinus Torvalds * dir. 20291da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20301da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20311da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20321da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20331da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20341da177e4SLinus Torvalds */ 2035a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 20361da177e4SLinus Torvalds { 20371da177e4SLinus Torvalds if (child->d_inode) 20381da177e4SLinus Torvalds return -EEXIST; 20391da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20401da177e4SLinus Torvalds return -ENOENT; 2041f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 20421da177e4SLinus Torvalds } 20431da177e4SLinus Torvalds 20441da177e4SLinus Torvalds /* 20451da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 20461da177e4SLinus Torvalds */ 20471da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 20481da177e4SLinus Torvalds { 20491da177e4SLinus Torvalds struct dentry *p; 20501da177e4SLinus Torvalds 20511da177e4SLinus Torvalds if (p1 == p2) { 2052f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 20531da177e4SLinus Torvalds return NULL; 20541da177e4SLinus Torvalds } 20551da177e4SLinus Torvalds 2056a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20571da177e4SLinus Torvalds 2058e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2059e2761a11SOGAWA Hirofumi if (p) { 2060f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2061f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 20621da177e4SLinus Torvalds return p; 20631da177e4SLinus Torvalds } 20641da177e4SLinus Torvalds 2065e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2066e2761a11SOGAWA Hirofumi if (p) { 2067f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2068f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20691da177e4SLinus Torvalds return p; 20701da177e4SLinus Torvalds } 20711da177e4SLinus Torvalds 2072f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2073f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20741da177e4SLinus Torvalds return NULL; 20751da177e4SLinus Torvalds } 20761da177e4SLinus Torvalds 20771da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 20781da177e4SLinus Torvalds { 20791b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 20801da177e4SLinus Torvalds if (p1 != p2) { 20811b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2082a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20831da177e4SLinus Torvalds } 20841da177e4SLinus Torvalds } 20851da177e4SLinus Torvalds 20861da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 20871da177e4SLinus Torvalds struct nameidata *nd) 20881da177e4SLinus Torvalds { 2089a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20901da177e4SLinus Torvalds 20911da177e4SLinus Torvalds if (error) 20921da177e4SLinus Torvalds return error; 20931da177e4SLinus Torvalds 2094acfa4380SAl Viro if (!dir->i_op->create) 20951da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 20961da177e4SLinus Torvalds mode &= S_IALLUGO; 20971da177e4SLinus Torvalds mode |= S_IFREG; 20981da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 20991da177e4SLinus Torvalds if (error) 21001da177e4SLinus Torvalds return error; 21011da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 2102a74574aaSStephen Smalley if (!error) 2103f38aa942SAmy Griffis fsnotify_create(dir, dentry); 21041da177e4SLinus Torvalds return error; 21051da177e4SLinus Torvalds } 21061da177e4SLinus Torvalds 21073fb64190SChristoph Hellwig int may_open(struct path *path, int acc_mode, int flag) 21081da177e4SLinus Torvalds { 21093fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21101da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21111da177e4SLinus Torvalds int error; 21121da177e4SLinus Torvalds 21131da177e4SLinus Torvalds if (!inode) 21141da177e4SLinus Torvalds return -ENOENT; 21151da177e4SLinus Torvalds 2116c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2117c8fe8f30SChristoph Hellwig case S_IFLNK: 21181da177e4SLinus Torvalds return -ELOOP; 2119c8fe8f30SChristoph Hellwig case S_IFDIR: 2120c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21211da177e4SLinus Torvalds return -EISDIR; 2122c8fe8f30SChristoph Hellwig break; 2123c8fe8f30SChristoph Hellwig case S_IFBLK: 2124c8fe8f30SChristoph Hellwig case S_IFCHR: 21253fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21261da177e4SLinus Torvalds return -EACCES; 2127c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2128c8fe8f30SChristoph Hellwig case S_IFIFO: 2129c8fe8f30SChristoph Hellwig case S_IFSOCK: 21301da177e4SLinus Torvalds flag &= ~O_TRUNC; 2131c8fe8f30SChristoph Hellwig break; 21324a3fd211SDave Hansen } 2133b41572e9SDave Hansen 21343fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2135b41572e9SDave Hansen if (error) 2136b41572e9SDave Hansen return error; 21376146f0d5SMimi Zohar 21381da177e4SLinus Torvalds /* 21391da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 21401da177e4SLinus Torvalds */ 21411da177e4SLinus Torvalds if (IS_APPEND(inode)) { 21428737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 21437715b521SAl Viro return -EPERM; 21441da177e4SLinus Torvalds if (flag & O_TRUNC) 21457715b521SAl Viro return -EPERM; 21461da177e4SLinus Torvalds } 21471da177e4SLinus Torvalds 21481da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 21497715b521SAl Viro if (flag & O_NOATIME && !is_owner_or_cap(inode)) 21507715b521SAl Viro return -EPERM; 21511da177e4SLinus Torvalds 21521da177e4SLinus Torvalds /* 21531da177e4SLinus Torvalds * Ensure there are no outstanding leases on the file. 21541da177e4SLinus Torvalds */ 2155b65a9cfcSAl Viro return break_lease(inode, flag); 21567715b521SAl Viro } 21577715b521SAl Viro 2158e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 21597715b521SAl Viro { 2160e1181ee6SJeff Layton struct path *path = &filp->f_path; 21617715b521SAl Viro struct inode *inode = path->dentry->d_inode; 21627715b521SAl Viro int error = get_write_access(inode); 21631da177e4SLinus Torvalds if (error) 21647715b521SAl Viro return error; 21651da177e4SLinus Torvalds /* 21661da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 21671da177e4SLinus Torvalds */ 21681da177e4SLinus Torvalds error = locks_verify_locked(inode); 2169be6d3e56SKentaro Takeda if (!error) 2170ea0d3ab2STetsuo Handa error = security_path_truncate(path); 21711da177e4SLinus Torvalds if (!error) { 21727715b521SAl Viro error = do_truncate(path->dentry, 0, 2173d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2174e1181ee6SJeff Layton filp); 21751da177e4SLinus Torvalds } 21761da177e4SLinus Torvalds put_write_access(inode); 2177acd0c935SMimi Zohar return error; 21781da177e4SLinus Torvalds } 21791da177e4SLinus Torvalds 2180d57999e1SDave Hansen /* 2181d57999e1SDave Hansen * Be careful about ever adding any more callers of this 2182d57999e1SDave Hansen * function. Its flags must be in the namei format, not 2183d57999e1SDave Hansen * what get passed to sys_open(). 2184d57999e1SDave Hansen */ 2185d57999e1SDave Hansen static int __open_namei_create(struct nameidata *nd, struct path *path, 21868737c930SAl Viro int open_flag, int mode) 2187aab520e2SDave Hansen { 2188aab520e2SDave Hansen int error; 21894ac91378SJan Blunck struct dentry *dir = nd->path.dentry; 2190aab520e2SDave Hansen 2191aab520e2SDave Hansen if (!IS_POSIXACL(dir->d_inode)) 2192ce3b0f8dSAl Viro mode &= ~current_umask(); 2193be6d3e56SKentaro Takeda error = security_path_mknod(&nd->path, path->dentry, mode, 0); 2194be6d3e56SKentaro Takeda if (error) 2195be6d3e56SKentaro Takeda goto out_unlock; 2196aab520e2SDave Hansen error = vfs_create(dir->d_inode, path->dentry, mode, nd); 2197be6d3e56SKentaro Takeda out_unlock: 2198aab520e2SDave Hansen mutex_unlock(&dir->d_inode->i_mutex); 21994ac91378SJan Blunck dput(nd->path.dentry); 22004ac91378SJan Blunck nd->path.dentry = path->dentry; 220131e6b01fSNick Piggin 2202aab520e2SDave Hansen if (error) 2203aab520e2SDave Hansen return error; 2204aab520e2SDave Hansen /* Don't check for write permission, don't truncate */ 22058737c930SAl Viro return may_open(&nd->path, 0, open_flag & ~O_TRUNC); 2206aab520e2SDave Hansen } 2207aab520e2SDave Hansen 22081da177e4SLinus Torvalds /* 2209d57999e1SDave Hansen * Note that while the flag value (low two bits) for sys_open means: 2210d57999e1SDave Hansen * 00 - read-only 2211d57999e1SDave Hansen * 01 - write-only 2212d57999e1SDave Hansen * 10 - read-write 2213d57999e1SDave Hansen * 11 - special 2214d57999e1SDave Hansen * it is changed into 2215d57999e1SDave Hansen * 00 - no permissions needed 2216d57999e1SDave Hansen * 01 - read-permission 2217d57999e1SDave Hansen * 10 - write-permission 2218d57999e1SDave Hansen * 11 - read-write 2219d57999e1SDave Hansen * for the internal routines (ie open_namei()/follow_link() etc) 2220d57999e1SDave Hansen * This is more logical, and also allows the 00 "no perm needed" 2221d57999e1SDave Hansen * to be used for symlinks (where the permissions are checked 2222d57999e1SDave Hansen * later). 2223d57999e1SDave Hansen * 2224d57999e1SDave Hansen */ 2225d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2226d57999e1SDave Hansen { 2227d57999e1SDave Hansen if ((flag+1) & O_ACCMODE) 2228d57999e1SDave Hansen flag++; 2229d57999e1SDave Hansen return flag; 2230d57999e1SDave Hansen } 2231d57999e1SDave Hansen 22327715b521SAl Viro static int open_will_truncate(int flag, struct inode *inode) 22334a3fd211SDave Hansen { 2234d57999e1SDave Hansen /* 22354a3fd211SDave Hansen * We'll never write to the fs underlying 22364a3fd211SDave Hansen * a device file. 22374a3fd211SDave Hansen */ 22384a3fd211SDave Hansen if (special_file(inode->i_mode)) 22394a3fd211SDave Hansen return 0; 22404a3fd211SDave Hansen return (flag & O_TRUNC); 22414a3fd211SDave Hansen } 22424a3fd211SDave Hansen 2243648fa861SAl Viro static struct file *finish_open(struct nameidata *nd, 22449a66179eSAl Viro int open_flag, int acc_mode) 2245648fa861SAl Viro { 2246648fa861SAl Viro struct file *filp; 2247648fa861SAl Viro int will_truncate; 2248648fa861SAl Viro int error; 2249648fa861SAl Viro 22509a66179eSAl Viro will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode); 2251648fa861SAl Viro if (will_truncate) { 2252648fa861SAl Viro error = mnt_want_write(nd->path.mnt); 2253648fa861SAl Viro if (error) 2254648fa861SAl Viro goto exit; 2255648fa861SAl Viro } 2256648fa861SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2257648fa861SAl Viro if (error) { 2258648fa861SAl Viro if (will_truncate) 2259648fa861SAl Viro mnt_drop_write(nd->path.mnt); 2260648fa861SAl Viro goto exit; 2261648fa861SAl Viro } 2262648fa861SAl Viro filp = nameidata_to_filp(nd); 2263648fa861SAl Viro if (!IS_ERR(filp)) { 2264648fa861SAl Viro error = ima_file_check(filp, acc_mode); 2265648fa861SAl Viro if (error) { 2266648fa861SAl Viro fput(filp); 2267648fa861SAl Viro filp = ERR_PTR(error); 2268648fa861SAl Viro } 2269648fa861SAl Viro } 2270648fa861SAl Viro if (!IS_ERR(filp)) { 2271648fa861SAl Viro if (will_truncate) { 2272e1181ee6SJeff Layton error = handle_truncate(filp); 2273648fa861SAl Viro if (error) { 2274648fa861SAl Viro fput(filp); 2275648fa861SAl Viro filp = ERR_PTR(error); 2276648fa861SAl Viro } 2277648fa861SAl Viro } 2278648fa861SAl Viro } 2279648fa861SAl Viro /* 2280648fa861SAl Viro * It is now safe to drop the mnt write 2281648fa861SAl Viro * because the filp has had a write taken 2282648fa861SAl Viro * on its behalf. 2283648fa861SAl Viro */ 2284648fa861SAl Viro if (will_truncate) 2285648fa861SAl Viro mnt_drop_write(nd->path.mnt); 2286d893f1bcSAl Viro path_put(&nd->path); 2287648fa861SAl Viro return filp; 2288648fa861SAl Viro 2289648fa861SAl Viro exit: 2290648fa861SAl Viro if (!IS_ERR(nd->intent.open.file)) 2291648fa861SAl Viro release_open_intent(nd); 2292648fa861SAl Viro path_put(&nd->path); 2293648fa861SAl Viro return ERR_PTR(error); 2294648fa861SAl Viro } 2295648fa861SAl Viro 229631e6b01fSNick Piggin /* 229731e6b01fSNick Piggin * Handle O_CREAT case for do_filp_open 229831e6b01fSNick Piggin */ 2299fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 23005b369df8SAl Viro int open_flag, int acc_mode, 23013e297b61SAl Viro int mode, const char *pathname) 2302fb1cc555SAl Viro { 2303a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2304fb1cc555SAl Viro struct file *filp; 23051f36f774SAl Viro int error = -EISDIR; 2306fb1cc555SAl Viro 23071f36f774SAl Viro switch (nd->last_type) { 23081f36f774SAl Viro case LAST_DOTDOT: 23091f36f774SAl Viro follow_dotdot(nd); 23101f36f774SAl Viro dir = nd->path.dentry; 2311176306f5SNeil Brown case LAST_DOT: 2312fb045adbSNick Piggin if (need_reval_dot(dir)) { 2313f20877d9SJ. R. Okajima int status = d_revalidate(nd->path.dentry, nd); 2314f20877d9SJ. R. Okajima if (!status) 2315f20877d9SJ. R. Okajima status = -ESTALE; 2316f20877d9SJ. R. Okajima if (status < 0) { 2317f20877d9SJ. R. Okajima error = status; 2318a2c36b45SAl Viro goto exit; 23191f36f774SAl Viro } 2320f20877d9SJ. R. Okajima } 23211f36f774SAl Viro /* fallthrough */ 23221f36f774SAl Viro case LAST_ROOT: 23231f36f774SAl Viro goto exit; 23241f36f774SAl Viro case LAST_BIND: 23251f36f774SAl Viro audit_inode(pathname, dir); 23261f36f774SAl Viro goto ok; 23271f36f774SAl Viro } 2328a2c36b45SAl Viro 23291f36f774SAl Viro /* trailing slashes? */ 233031e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 23311f36f774SAl Viro goto exit; 23321f36f774SAl Viro 2333a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2334a1e28038SAl Viro 2335a1e28038SAl Viro path->dentry = lookup_hash(nd); 2336a1e28038SAl Viro path->mnt = nd->path.mnt; 2337a1e28038SAl Viro 2338fb1cc555SAl Viro error = PTR_ERR(path->dentry); 2339fb1cc555SAl Viro if (IS_ERR(path->dentry)) { 2340fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2341fb1cc555SAl Viro goto exit; 2342fb1cc555SAl Viro } 2343fb1cc555SAl Viro 2344fb1cc555SAl Viro if (IS_ERR(nd->intent.open.file)) { 2345fb1cc555SAl Viro error = PTR_ERR(nd->intent.open.file); 2346fb1cc555SAl Viro goto exit_mutex_unlock; 2347fb1cc555SAl Viro } 2348fb1cc555SAl Viro 2349fb1cc555SAl Viro /* Negative dentry, just create the file */ 2350fb1cc555SAl Viro if (!path->dentry->d_inode) { 2351fb1cc555SAl Viro /* 2352fb1cc555SAl Viro * This write is needed to ensure that a 2353fb1cc555SAl Viro * ro->rw transition does not occur between 2354fb1cc555SAl Viro * the time when the file is created and when 2355fb1cc555SAl Viro * a permanent write count is taken through 2356fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2357fb1cc555SAl Viro */ 2358fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2359fb1cc555SAl Viro if (error) 2360fb1cc555SAl Viro goto exit_mutex_unlock; 2361fb1cc555SAl Viro error = __open_namei_create(nd, path, open_flag, mode); 2362fb1cc555SAl Viro if (error) { 2363fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 2364fb1cc555SAl Viro goto exit; 2365fb1cc555SAl Viro } 2366fb1cc555SAl Viro filp = nameidata_to_filp(nd); 2367fb1cc555SAl Viro mnt_drop_write(nd->path.mnt); 2368d893f1bcSAl Viro path_put(&nd->path); 2369fb1cc555SAl Viro if (!IS_ERR(filp)) { 2370fb1cc555SAl Viro error = ima_file_check(filp, acc_mode); 2371fb1cc555SAl Viro if (error) { 2372fb1cc555SAl Viro fput(filp); 2373fb1cc555SAl Viro filp = ERR_PTR(error); 2374fb1cc555SAl Viro } 2375fb1cc555SAl Viro } 2376fb1cc555SAl Viro return filp; 2377fb1cc555SAl Viro } 2378fb1cc555SAl Viro 2379fb1cc555SAl Viro /* 2380fb1cc555SAl Viro * It already exists. 2381fb1cc555SAl Viro */ 2382fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2383fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2384fb1cc555SAl Viro 2385fb1cc555SAl Viro error = -EEXIST; 23865b369df8SAl Viro if (open_flag & O_EXCL) 2387fb1cc555SAl Viro goto exit_dput; 2388fb1cc555SAl Viro 23899875cf80SDavid Howells error = follow_managed(path, nd->flags); 23909875cf80SDavid Howells if (error < 0) 2391fb1cc555SAl Viro goto exit_dput; 2392fb1cc555SAl Viro 2393fb1cc555SAl Viro error = -ENOENT; 2394fb1cc555SAl Viro if (!path->dentry->d_inode) 2395fb1cc555SAl Viro goto exit_dput; 23969e67f361SAl Viro 23979e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2398fb1cc555SAl Viro return NULL; 2399fb1cc555SAl Viro 2400fb1cc555SAl Viro path_to_nameidata(path, nd); 240131e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2402fb1cc555SAl Viro error = -EISDIR; 240331e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2404fb1cc555SAl Viro goto exit; 240567ee3ad2SAl Viro ok: 24069a66179eSAl Viro filp = finish_open(nd, open_flag, acc_mode); 2407fb1cc555SAl Viro return filp; 2408fb1cc555SAl Viro 2409fb1cc555SAl Viro exit_mutex_unlock: 2410fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2411fb1cc555SAl Viro exit_dput: 2412fb1cc555SAl Viro path_put_conditional(path, nd); 2413fb1cc555SAl Viro exit: 2414fb1cc555SAl Viro if (!IS_ERR(nd->intent.open.file)) 2415fb1cc555SAl Viro release_open_intent(nd); 2416fb1cc555SAl Viro path_put(&nd->path); 2417fb1cc555SAl Viro return ERR_PTR(error); 2418fb1cc555SAl Viro } 2419fb1cc555SAl Viro 24204a3fd211SDave Hansen /* 24214a3fd211SDave Hansen * Note that the low bits of the passed in "open_flag" 24224a3fd211SDave Hansen * are not the same as in the local variable "flag". See 24234a3fd211SDave Hansen * open_to_namei_flags() for more details. 24241da177e4SLinus Torvalds */ 2425a70e65dfSChristoph Hellwig struct file *do_filp_open(int dfd, const char *pathname, 24266e8341a1SAl Viro int open_flag, int mode, int acc_mode) 24271da177e4SLinus Torvalds { 24284a3fd211SDave Hansen struct file *filp; 2429a70e65dfSChristoph Hellwig struct nameidata nd; 24306e8341a1SAl Viro int error; 24319850c056SAl Viro struct path path; 24321da177e4SLinus Torvalds int count = 0; 2433d57999e1SDave Hansen int flag = open_to_namei_flags(open_flag); 243431e6b01fSNick Piggin int flags; 24351f36f774SAl Viro 24361f36f774SAl Viro if (!(open_flag & O_CREAT)) 24371f36f774SAl Viro mode = 0; 24381da177e4SLinus Torvalds 2439b1085ba8SLino Sanfilippo /* Must never be set by userspace */ 2440b1085ba8SLino Sanfilippo open_flag &= ~FMODE_NONOTIFY; 2441b1085ba8SLino Sanfilippo 24426b2f3d1fSChristoph Hellwig /* 24436b2f3d1fSChristoph Hellwig * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only 24446b2f3d1fSChristoph Hellwig * check for O_DSYNC if the need any syncing at all we enforce it's 24456b2f3d1fSChristoph Hellwig * always set instead of having to deal with possibly weird behaviour 24466b2f3d1fSChristoph Hellwig * for malicious applications setting only __O_SYNC. 24476b2f3d1fSChristoph Hellwig */ 24486b2f3d1fSChristoph Hellwig if (open_flag & __O_SYNC) 24496b2f3d1fSChristoph Hellwig open_flag |= O_DSYNC; 24506b2f3d1fSChristoph Hellwig 24516e8341a1SAl Viro if (!acc_mode) 24526d125529SAl Viro acc_mode = MAY_OPEN | ACC_MODE(open_flag); 24531da177e4SLinus Torvalds 2454834f2a4aSTrond Myklebust /* O_TRUNC implies we need access checks for write permissions */ 24554296e2cbSAl Viro if (open_flag & O_TRUNC) 2456834f2a4aSTrond Myklebust acc_mode |= MAY_WRITE; 2457834f2a4aSTrond Myklebust 24581da177e4SLinus Torvalds /* Allow the LSM permission hook to distinguish append 24591da177e4SLinus Torvalds access from general write access. */ 24604296e2cbSAl Viro if (open_flag & O_APPEND) 24611da177e4SLinus Torvalds acc_mode |= MAY_APPEND; 24621da177e4SLinus Torvalds 246331e6b01fSNick Piggin flags = LOOKUP_OPEN; 246431e6b01fSNick Piggin if (open_flag & O_CREAT) { 246531e6b01fSNick Piggin flags |= LOOKUP_CREATE; 246631e6b01fSNick Piggin if (open_flag & O_EXCL) 246731e6b01fSNick Piggin flags |= LOOKUP_EXCL; 2468654f562cSJ. R. Okajima } 246931e6b01fSNick Piggin if (open_flag & O_DIRECTORY) 247031e6b01fSNick Piggin flags |= LOOKUP_DIRECTORY; 247131e6b01fSNick Piggin if (!(open_flag & O_NOFOLLOW)) 247231e6b01fSNick Piggin flags |= LOOKUP_FOLLOW; 247331e6b01fSNick Piggin 247431e6b01fSNick Piggin filp = get_empty_filp(); 247531e6b01fSNick Piggin if (!filp) 247631e6b01fSNick Piggin return ERR_PTR(-ENFILE); 247731e6b01fSNick Piggin 247831e6b01fSNick Piggin filp->f_flags = open_flag; 247931e6b01fSNick Piggin nd.intent.open.file = filp; 248031e6b01fSNick Piggin nd.intent.open.flags = flag; 248131e6b01fSNick Piggin nd.intent.open.create_mode = mode; 248231e6b01fSNick Piggin 248331e6b01fSNick Piggin if (open_flag & O_CREAT) 248431e6b01fSNick Piggin goto creat; 248531e6b01fSNick Piggin 248631e6b01fSNick Piggin /* !O_CREAT, simple open */ 248731e6b01fSNick Piggin error = do_path_lookup(dfd, pathname, flags, &nd); 248831e6b01fSNick Piggin if (unlikely(error)) 248931e6b01fSNick Piggin goto out_filp; 249031e6b01fSNick Piggin error = -ELOOP; 249131e6b01fSNick Piggin if (!(nd.flags & LOOKUP_FOLLOW)) { 249231e6b01fSNick Piggin if (nd.inode->i_op->follow_link) 249331e6b01fSNick Piggin goto out_path; 249431e6b01fSNick Piggin } 249531e6b01fSNick Piggin error = -ENOTDIR; 249631e6b01fSNick Piggin if (nd.flags & LOOKUP_DIRECTORY) { 249731e6b01fSNick Piggin if (!nd.inode->i_op->lookup) 249831e6b01fSNick Piggin goto out_path; 249931e6b01fSNick Piggin } 250031e6b01fSNick Piggin audit_inode(pathname, nd.path.dentry); 250131e6b01fSNick Piggin filp = finish_open(&nd, open_flag, acc_mode); 250231e6b01fSNick Piggin return filp; 250331e6b01fSNick Piggin 250431e6b01fSNick Piggin creat: 250531e6b01fSNick Piggin /* OK, have to create the file. Find the parent. */ 250631e6b01fSNick Piggin error = path_init_rcu(dfd, pathname, 250731e6b01fSNick Piggin LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd); 250831e6b01fSNick Piggin if (error) 250931e6b01fSNick Piggin goto out_filp; 251031e6b01fSNick Piggin error = path_walk_rcu(pathname, &nd); 251131e6b01fSNick Piggin path_finish_rcu(&nd); 251231e6b01fSNick Piggin if (unlikely(error == -ECHILD || error == -ESTALE)) { 251331e6b01fSNick Piggin /* slower, locked walk */ 251431e6b01fSNick Piggin if (error == -ESTALE) { 251531e6b01fSNick Piggin reval: 251631e6b01fSNick Piggin flags |= LOOKUP_REVAL; 251731e6b01fSNick Piggin } 251831e6b01fSNick Piggin error = path_init(dfd, pathname, 251931e6b01fSNick Piggin LOOKUP_PARENT | (flags & LOOKUP_REVAL), &nd); 252031e6b01fSNick Piggin if (error) 252131e6b01fSNick Piggin goto out_filp; 252231e6b01fSNick Piggin 252331e6b01fSNick Piggin error = path_walk_simple(pathname, &nd); 252431e6b01fSNick Piggin } 252531e6b01fSNick Piggin if (unlikely(error)) 252631e6b01fSNick Piggin goto out_filp; 252731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) 25289b4a9b14SAl Viro audit_inode(pathname, nd.path.dentry); 25291da177e4SLinus Torvalds 25301da177e4SLinus Torvalds /* 2531a2c36b45SAl Viro * We have the parent and last component. 25321da177e4SLinus Torvalds */ 253331e6b01fSNick Piggin nd.flags = flags; 25343e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 2535806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 25367b9337aaSNick Piggin struct path link = path; 25377b9337aaSNick Piggin struct inode *linki = link.dentry->d_inode; 2538def4af30SAl Viro void *cookie; 2539806b681cSAl Viro error = -ELOOP; 25401f36f774SAl Viro /* S_ISDIR part is a temporary automount kludge */ 25417b9337aaSNick Piggin if (!(nd.flags & LOOKUP_FOLLOW) && !S_ISDIR(linki->i_mode)) 25421f36f774SAl Viro goto exit_dput; 25431f36f774SAl Viro if (count++ == 32) 2544806b681cSAl Viro goto exit_dput; 2545806b681cSAl Viro /* 2546806b681cSAl Viro * This is subtle. Instead of calling do_follow_link() we do 2547806b681cSAl Viro * the thing by hands. The reason is that this way we have zero 2548806b681cSAl Viro * link_count and path_walk() (called from ->follow_link) 2549806b681cSAl Viro * honoring LOOKUP_PARENT. After that we have the parent and 2550806b681cSAl Viro * last component, i.e. we are in the same situation as after 2551806b681cSAl Viro * the first path_walk(). Well, almost - if the last component 2552806b681cSAl Viro * is normal we get its copy stored in nd->last.name and we will 2553806b681cSAl Viro * have to putname() it when we are done. Procfs-like symlinks 2554806b681cSAl Viro * just set LAST_BIND. 2555806b681cSAl Viro */ 2556806b681cSAl Viro nd.flags |= LOOKUP_PARENT; 25577b9337aaSNick Piggin error = security_inode_follow_link(link.dentry, &nd); 2558806b681cSAl Viro if (error) 2559806b681cSAl Viro goto exit_dput; 25607b9337aaSNick Piggin error = __do_follow_link(&link, &nd, &cookie); 2561def4af30SAl Viro if (unlikely(error)) { 25627b9337aaSNick Piggin if (!IS_ERR(cookie) && linki->i_op->put_link) 25637b9337aaSNick Piggin linki->i_op->put_link(link.dentry, &nd, cookie); 2564806b681cSAl Viro /* nd.path had been dropped */ 25657b9337aaSNick Piggin nd.path = link; 256631e6b01fSNick Piggin goto out_path; 2567806b681cSAl Viro } 2568806b681cSAl Viro nd.flags &= ~LOOKUP_PARENT; 25693e297b61SAl Viro filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); 25707b9337aaSNick Piggin if (linki->i_op->put_link) 25717b9337aaSNick Piggin linki->i_op->put_link(link.dentry, &nd, cookie); 25727b9337aaSNick Piggin path_put(&link); 2573806b681cSAl Viro } 257410fa8e62SAl Viro out: 25752a737871SAl Viro if (nd.root.mnt) 25762a737871SAl Viro path_put(&nd.root); 257731e6b01fSNick Piggin if (filp == ERR_PTR(-ESTALE) && !(flags & LOOKUP_REVAL)) 257810fa8e62SAl Viro goto reval; 257910fa8e62SAl Viro return filp; 25801da177e4SLinus Torvalds 2581806b681cSAl Viro exit_dput: 2582806b681cSAl Viro path_put_conditional(&path, &nd); 258331e6b01fSNick Piggin out_path: 258431e6b01fSNick Piggin path_put(&nd.path); 258531e6b01fSNick Piggin out_filp: 2586806b681cSAl Viro if (!IS_ERR(nd.intent.open.file)) 2587a70e65dfSChristoph Hellwig release_open_intent(&nd); 258810fa8e62SAl Viro filp = ERR_PTR(error); 258910fa8e62SAl Viro goto out; 2590de459215SKirill Korotaev } 25911da177e4SLinus Torvalds 25921da177e4SLinus Torvalds /** 2593a70e65dfSChristoph Hellwig * filp_open - open file and return file pointer 2594a70e65dfSChristoph Hellwig * 2595a70e65dfSChristoph Hellwig * @filename: path to open 2596a70e65dfSChristoph Hellwig * @flags: open flags as per the open(2) second argument 2597a70e65dfSChristoph Hellwig * @mode: mode for the new file if O_CREAT is set, else ignored 2598a70e65dfSChristoph Hellwig * 2599a70e65dfSChristoph Hellwig * This is the helper to open a file from kernelspace if you really 2600a70e65dfSChristoph Hellwig * have to. But in generally you should not do this, so please move 2601a70e65dfSChristoph Hellwig * along, nothing to see here.. 2602a70e65dfSChristoph Hellwig */ 2603a70e65dfSChristoph Hellwig struct file *filp_open(const char *filename, int flags, int mode) 2604a70e65dfSChristoph Hellwig { 26056e8341a1SAl Viro return do_filp_open(AT_FDCWD, filename, flags, mode, 0); 2606a70e65dfSChristoph Hellwig } 2607a70e65dfSChristoph Hellwig EXPORT_SYMBOL(filp_open); 2608a70e65dfSChristoph Hellwig 2609a70e65dfSChristoph Hellwig /** 26101da177e4SLinus Torvalds * lookup_create - lookup a dentry, creating it if it doesn't exist 26111da177e4SLinus Torvalds * @nd: nameidata info 26121da177e4SLinus Torvalds * @is_dir: directory flag 26131da177e4SLinus Torvalds * 26141da177e4SLinus Torvalds * Simple function to lookup and return a dentry and create it 26151da177e4SLinus Torvalds * if it doesn't exist. Is SMP-safe. 2616c663e5d8SChristoph Hellwig * 26174ac91378SJan Blunck * Returns with nd->path.dentry->d_inode->i_mutex locked. 26181da177e4SLinus Torvalds */ 26191da177e4SLinus Torvalds struct dentry *lookup_create(struct nameidata *nd, int is_dir) 26201da177e4SLinus Torvalds { 2621c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 26221da177e4SLinus Torvalds 26234ac91378SJan Blunck mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2624c663e5d8SChristoph Hellwig /* 2625c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2626c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2627c663e5d8SChristoph Hellwig */ 26281da177e4SLinus Torvalds if (nd->last_type != LAST_NORM) 26291da177e4SLinus Torvalds goto fail; 26301da177e4SLinus Torvalds nd->flags &= ~LOOKUP_PARENT; 26313516586aSAl Viro nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2632a634904aSASANO Masahiro nd->intent.open.flags = O_EXCL; 2633c663e5d8SChristoph Hellwig 2634c663e5d8SChristoph Hellwig /* 2635c663e5d8SChristoph Hellwig * Do the final lookup. 2636c663e5d8SChristoph Hellwig */ 263749705b77SChristoph Hellwig dentry = lookup_hash(nd); 26381da177e4SLinus Torvalds if (IS_ERR(dentry)) 26391da177e4SLinus Torvalds goto fail; 2640c663e5d8SChristoph Hellwig 2641e9baf6e5SAl Viro if (dentry->d_inode) 2642e9baf6e5SAl Viro goto eexist; 2643c663e5d8SChristoph Hellwig /* 2644c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2645c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2646c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2647c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2648c663e5d8SChristoph Hellwig */ 2649e9baf6e5SAl Viro if (unlikely(!is_dir && nd->last.name[nd->last.len])) { 26501da177e4SLinus Torvalds dput(dentry); 26511da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2652e9baf6e5SAl Viro } 2653e9baf6e5SAl Viro return dentry; 2654e9baf6e5SAl Viro eexist: 2655e9baf6e5SAl Viro dput(dentry); 2656e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 26571da177e4SLinus Torvalds fail: 26581da177e4SLinus Torvalds return dentry; 26591da177e4SLinus Torvalds } 2660f81a0bffSChristoph Hellwig EXPORT_SYMBOL_GPL(lookup_create); 26611da177e4SLinus Torvalds 26621da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 26631da177e4SLinus Torvalds { 2664a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26651da177e4SLinus Torvalds 26661da177e4SLinus Torvalds if (error) 26671da177e4SLinus Torvalds return error; 26681da177e4SLinus Torvalds 26691da177e4SLinus Torvalds if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 26701da177e4SLinus Torvalds return -EPERM; 26711da177e4SLinus Torvalds 2672acfa4380SAl Viro if (!dir->i_op->mknod) 26731da177e4SLinus Torvalds return -EPERM; 26741da177e4SLinus Torvalds 267508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 267608ce5f16SSerge E. Hallyn if (error) 267708ce5f16SSerge E. Hallyn return error; 267808ce5f16SSerge E. Hallyn 26791da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 26801da177e4SLinus Torvalds if (error) 26811da177e4SLinus Torvalds return error; 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2684a74574aaSStephen Smalley if (!error) 2685f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26861da177e4SLinus Torvalds return error; 26871da177e4SLinus Torvalds } 26881da177e4SLinus Torvalds 2689463c3197SDave Hansen static int may_mknod(mode_t mode) 2690463c3197SDave Hansen { 2691463c3197SDave Hansen switch (mode & S_IFMT) { 2692463c3197SDave Hansen case S_IFREG: 2693463c3197SDave Hansen case S_IFCHR: 2694463c3197SDave Hansen case S_IFBLK: 2695463c3197SDave Hansen case S_IFIFO: 2696463c3197SDave Hansen case S_IFSOCK: 2697463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2698463c3197SDave Hansen return 0; 2699463c3197SDave Hansen case S_IFDIR: 2700463c3197SDave Hansen return -EPERM; 2701463c3197SDave Hansen default: 2702463c3197SDave Hansen return -EINVAL; 2703463c3197SDave Hansen } 2704463c3197SDave Hansen } 2705463c3197SDave Hansen 27062e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 27072e4d0924SHeiko Carstens unsigned, dev) 27081da177e4SLinus Torvalds { 27092ad94ae6SAl Viro int error; 27101da177e4SLinus Torvalds char *tmp; 27111da177e4SLinus Torvalds struct dentry *dentry; 27121da177e4SLinus Torvalds struct nameidata nd; 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds if (S_ISDIR(mode)) 27151da177e4SLinus Torvalds return -EPERM; 27161da177e4SLinus Torvalds 27172ad94ae6SAl Viro error = user_path_parent(dfd, filename, &nd, &tmp); 27181da177e4SLinus Torvalds if (error) 27192ad94ae6SAl Viro return error; 27202ad94ae6SAl Viro 27211da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 2722463c3197SDave Hansen if (IS_ERR(dentry)) { 27231da177e4SLinus Torvalds error = PTR_ERR(dentry); 2724463c3197SDave Hansen goto out_unlock; 2725463c3197SDave Hansen } 27264ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2727ce3b0f8dSAl Viro mode &= ~current_umask(); 2728463c3197SDave Hansen error = may_mknod(mode); 2729463c3197SDave Hansen if (error) 2730463c3197SDave Hansen goto out_dput; 2731463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2732463c3197SDave Hansen if (error) 2733463c3197SDave Hansen goto out_dput; 2734be6d3e56SKentaro Takeda error = security_path_mknod(&nd.path, dentry, mode, dev); 2735be6d3e56SKentaro Takeda if (error) 2736be6d3e56SKentaro Takeda goto out_drop_write; 27371da177e4SLinus Torvalds switch (mode & S_IFMT) { 27381da177e4SLinus Torvalds case 0: case S_IFREG: 27394ac91378SJan Blunck error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); 27401da177e4SLinus Torvalds break; 27411da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 27424ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, 27431da177e4SLinus Torvalds new_decode_dev(dev)); 27441da177e4SLinus Torvalds break; 27451da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 27464ac91378SJan Blunck error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); 27471da177e4SLinus Torvalds break; 27481da177e4SLinus Torvalds } 2749be6d3e56SKentaro Takeda out_drop_write: 2750463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2751463c3197SDave Hansen out_dput: 27521da177e4SLinus Torvalds dput(dentry); 2753463c3197SDave Hansen out_unlock: 27544ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27551d957f9bSJan Blunck path_put(&nd.path); 27561da177e4SLinus Torvalds putname(tmp); 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds return error; 27591da177e4SLinus Torvalds } 27601da177e4SLinus Torvalds 27613480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 27625590ff0dSUlrich Drepper { 27635590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 27645590ff0dSUlrich Drepper } 27655590ff0dSUlrich Drepper 27661da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 27671da177e4SLinus Torvalds { 2768a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27691da177e4SLinus Torvalds 27701da177e4SLinus Torvalds if (error) 27711da177e4SLinus Torvalds return error; 27721da177e4SLinus Torvalds 2773acfa4380SAl Viro if (!dir->i_op->mkdir) 27741da177e4SLinus Torvalds return -EPERM; 27751da177e4SLinus Torvalds 27761da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 27771da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 27781da177e4SLinus Torvalds if (error) 27791da177e4SLinus Torvalds return error; 27801da177e4SLinus Torvalds 27811da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2782a74574aaSStephen Smalley if (!error) 2783f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 27841da177e4SLinus Torvalds return error; 27851da177e4SLinus Torvalds } 27861da177e4SLinus Torvalds 27872e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 27881da177e4SLinus Torvalds { 27891da177e4SLinus Torvalds int error = 0; 27901da177e4SLinus Torvalds char * tmp; 27916902d925SDave Hansen struct dentry *dentry; 27926902d925SDave Hansen struct nameidata nd; 27931da177e4SLinus Torvalds 27942ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &tmp); 27952ad94ae6SAl Viro if (error) 27966902d925SDave Hansen goto out_err; 27971da177e4SLinus Torvalds 27981da177e4SLinus Torvalds dentry = lookup_create(&nd, 1); 27991da177e4SLinus Torvalds error = PTR_ERR(dentry); 28006902d925SDave Hansen if (IS_ERR(dentry)) 28016902d925SDave Hansen goto out_unlock; 28026902d925SDave Hansen 28034ac91378SJan Blunck if (!IS_POSIXACL(nd.path.dentry->d_inode)) 2804ce3b0f8dSAl Viro mode &= ~current_umask(); 2805463c3197SDave Hansen error = mnt_want_write(nd.path.mnt); 2806463c3197SDave Hansen if (error) 2807463c3197SDave Hansen goto out_dput; 2808be6d3e56SKentaro Takeda error = security_path_mkdir(&nd.path, dentry, mode); 2809be6d3e56SKentaro Takeda if (error) 2810be6d3e56SKentaro Takeda goto out_drop_write; 28114ac91378SJan Blunck error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); 2812be6d3e56SKentaro Takeda out_drop_write: 2813463c3197SDave Hansen mnt_drop_write(nd.path.mnt); 2814463c3197SDave Hansen out_dput: 28151da177e4SLinus Torvalds dput(dentry); 28166902d925SDave Hansen out_unlock: 28174ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28181d957f9bSJan Blunck path_put(&nd.path); 28191da177e4SLinus Torvalds putname(tmp); 28206902d925SDave Hansen out_err: 28211da177e4SLinus Torvalds return error; 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds 28243cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 28255590ff0dSUlrich Drepper { 28265590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 28275590ff0dSUlrich Drepper } 28285590ff0dSUlrich Drepper 28291da177e4SLinus Torvalds /* 28301da177e4SLinus Torvalds * We try to drop the dentry early: we should have 28311da177e4SLinus Torvalds * a usage count of 2 if we're the only user of this 28321da177e4SLinus Torvalds * dentry, and if that is true (possibly after pruning 28331da177e4SLinus Torvalds * the dcache), then we drop the dentry now. 28341da177e4SLinus Torvalds * 28351da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 28361da177e4SLinus Torvalds * do a 28371da177e4SLinus Torvalds * 28381da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 28391da177e4SLinus Torvalds * return -EBUSY; 28401da177e4SLinus Torvalds * 28411da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 28421da177e4SLinus Torvalds * that is still in use by something else.. 28431da177e4SLinus Torvalds */ 28441da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 28451da177e4SLinus Torvalds { 28461da177e4SLinus Torvalds dget(dentry); 28471da177e4SLinus Torvalds shrink_dcache_parent(dentry); 28481da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 2849b7ab39f6SNick Piggin if (dentry->d_count == 2) 28501da177e4SLinus Torvalds __d_drop(dentry); 28511da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 28521da177e4SLinus Torvalds } 28531da177e4SLinus Torvalds 28541da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 28551da177e4SLinus Torvalds { 28561da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 28571da177e4SLinus Torvalds 28581da177e4SLinus Torvalds if (error) 28591da177e4SLinus Torvalds return error; 28601da177e4SLinus Torvalds 2861acfa4380SAl Viro if (!dir->i_op->rmdir) 28621da177e4SLinus Torvalds return -EPERM; 28631da177e4SLinus Torvalds 28641b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 28651da177e4SLinus Torvalds dentry_unhash(dentry); 28661da177e4SLinus Torvalds if (d_mountpoint(dentry)) 28671da177e4SLinus Torvalds error = -EBUSY; 28681da177e4SLinus Torvalds else { 28691da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 28701da177e4SLinus Torvalds if (!error) { 28711da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2872d83c49f3SAl Viro if (!error) { 28731da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2874d83c49f3SAl Viro dont_mount(dentry); 2875d83c49f3SAl Viro } 28761da177e4SLinus Torvalds } 28771da177e4SLinus Torvalds } 28781b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 28791da177e4SLinus Torvalds if (!error) { 28801da177e4SLinus Torvalds d_delete(dentry); 28811da177e4SLinus Torvalds } 28821da177e4SLinus Torvalds dput(dentry); 28831da177e4SLinus Torvalds 28841da177e4SLinus Torvalds return error; 28851da177e4SLinus Torvalds } 28861da177e4SLinus Torvalds 28875590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 28881da177e4SLinus Torvalds { 28891da177e4SLinus Torvalds int error = 0; 28901da177e4SLinus Torvalds char * name; 28911da177e4SLinus Torvalds struct dentry *dentry; 28921da177e4SLinus Torvalds struct nameidata nd; 28931da177e4SLinus Torvalds 28942ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 28951da177e4SLinus Torvalds if (error) 28962ad94ae6SAl Viro return error; 28971da177e4SLinus Torvalds 28981da177e4SLinus Torvalds switch(nd.last_type) { 28991da177e4SLinus Torvalds case LAST_DOTDOT: 29001da177e4SLinus Torvalds error = -ENOTEMPTY; 29011da177e4SLinus Torvalds goto exit1; 29021da177e4SLinus Torvalds case LAST_DOT: 29031da177e4SLinus Torvalds error = -EINVAL; 29041da177e4SLinus Torvalds goto exit1; 29051da177e4SLinus Torvalds case LAST_ROOT: 29061da177e4SLinus Torvalds error = -EBUSY; 29071da177e4SLinus Torvalds goto exit1; 29081da177e4SLinus Torvalds } 29090612d9fbSOGAWA Hirofumi 29100612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 29110612d9fbSOGAWA Hirofumi 29124ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 291349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 29141da177e4SLinus Torvalds error = PTR_ERR(dentry); 29156902d925SDave Hansen if (IS_ERR(dentry)) 29166902d925SDave Hansen goto exit2; 29170622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 29180622753bSDave Hansen if (error) 29190622753bSDave Hansen goto exit3; 2920be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2921be6d3e56SKentaro Takeda if (error) 2922be6d3e56SKentaro Takeda goto exit4; 29234ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2924be6d3e56SKentaro Takeda exit4: 29250622753bSDave Hansen mnt_drop_write(nd.path.mnt); 29260622753bSDave Hansen exit3: 29271da177e4SLinus Torvalds dput(dentry); 29286902d925SDave Hansen exit2: 29294ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29301da177e4SLinus Torvalds exit1: 29311d957f9bSJan Blunck path_put(&nd.path); 29321da177e4SLinus Torvalds putname(name); 29331da177e4SLinus Torvalds return error; 29341da177e4SLinus Torvalds } 29351da177e4SLinus Torvalds 29363cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 29375590ff0dSUlrich Drepper { 29385590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 29395590ff0dSUlrich Drepper } 29405590ff0dSUlrich Drepper 29411da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 29421da177e4SLinus Torvalds { 29431da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 29441da177e4SLinus Torvalds 29451da177e4SLinus Torvalds if (error) 29461da177e4SLinus Torvalds return error; 29471da177e4SLinus Torvalds 2948acfa4380SAl Viro if (!dir->i_op->unlink) 29491da177e4SLinus Torvalds return -EPERM; 29501da177e4SLinus Torvalds 29511b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 29521da177e4SLinus Torvalds if (d_mountpoint(dentry)) 29531da177e4SLinus Torvalds error = -EBUSY; 29541da177e4SLinus Torvalds else { 29551da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2956bec1052eSAl Viro if (!error) { 29571da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2958bec1052eSAl Viro if (!error) 2959d83c49f3SAl Viro dont_mount(dentry); 2960bec1052eSAl Viro } 29611da177e4SLinus Torvalds } 29621b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 29631da177e4SLinus Torvalds 29641da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 29651da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2966ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 29671da177e4SLinus Torvalds d_delete(dentry); 29681da177e4SLinus Torvalds } 29690eeca283SRobert Love 29701da177e4SLinus Torvalds return error; 29711da177e4SLinus Torvalds } 29721da177e4SLinus Torvalds 29731da177e4SLinus Torvalds /* 29741da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 29751b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 29761da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 29771da177e4SLinus Torvalds * while waiting on the I/O. 29781da177e4SLinus Torvalds */ 29795590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 29801da177e4SLinus Torvalds { 29812ad94ae6SAl Viro int error; 29821da177e4SLinus Torvalds char *name; 29831da177e4SLinus Torvalds struct dentry *dentry; 29841da177e4SLinus Torvalds struct nameidata nd; 29851da177e4SLinus Torvalds struct inode *inode = NULL; 29861da177e4SLinus Torvalds 29872ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 29881da177e4SLinus Torvalds if (error) 29892ad94ae6SAl Viro return error; 29902ad94ae6SAl Viro 29911da177e4SLinus Torvalds error = -EISDIR; 29921da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 29931da177e4SLinus Torvalds goto exit1; 29940612d9fbSOGAWA Hirofumi 29950612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 29960612d9fbSOGAWA Hirofumi 29974ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 299849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 29991da177e4SLinus Torvalds error = PTR_ERR(dentry); 30001da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 30011da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 30021da177e4SLinus Torvalds if (nd.last.name[nd.last.len]) 30031da177e4SLinus Torvalds goto slashes; 30041da177e4SLinus Torvalds inode = dentry->d_inode; 30051da177e4SLinus Torvalds if (inode) 30067de9c6eeSAl Viro ihold(inode); 30070622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 30080622753bSDave Hansen if (error) 30090622753bSDave Hansen goto exit2; 3010be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3011be6d3e56SKentaro Takeda if (error) 3012be6d3e56SKentaro Takeda goto exit3; 30134ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 3014be6d3e56SKentaro Takeda exit3: 30150622753bSDave Hansen mnt_drop_write(nd.path.mnt); 30161da177e4SLinus Torvalds exit2: 30171da177e4SLinus Torvalds dput(dentry); 30181da177e4SLinus Torvalds } 30194ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 30201da177e4SLinus Torvalds if (inode) 30211da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 30221da177e4SLinus Torvalds exit1: 30231d957f9bSJan Blunck path_put(&nd.path); 30241da177e4SLinus Torvalds putname(name); 30251da177e4SLinus Torvalds return error; 30261da177e4SLinus Torvalds 30271da177e4SLinus Torvalds slashes: 30281da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 30291da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 30301da177e4SLinus Torvalds goto exit2; 30311da177e4SLinus Torvalds } 30321da177e4SLinus Torvalds 30332e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 30345590ff0dSUlrich Drepper { 30355590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 30365590ff0dSUlrich Drepper return -EINVAL; 30375590ff0dSUlrich Drepper 30385590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 30395590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 30405590ff0dSUlrich Drepper 30415590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 30425590ff0dSUlrich Drepper } 30435590ff0dSUlrich Drepper 30443480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 30455590ff0dSUlrich Drepper { 30465590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 30475590ff0dSUlrich Drepper } 30485590ff0dSUlrich Drepper 3049db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 30501da177e4SLinus Torvalds { 3051a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 30521da177e4SLinus Torvalds 30531da177e4SLinus Torvalds if (error) 30541da177e4SLinus Torvalds return error; 30551da177e4SLinus Torvalds 3056acfa4380SAl Viro if (!dir->i_op->symlink) 30571da177e4SLinus Torvalds return -EPERM; 30581da177e4SLinus Torvalds 30591da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 30601da177e4SLinus Torvalds if (error) 30611da177e4SLinus Torvalds return error; 30621da177e4SLinus Torvalds 30631da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3064a74574aaSStephen Smalley if (!error) 3065f38aa942SAmy Griffis fsnotify_create(dir, dentry); 30661da177e4SLinus Torvalds return error; 30671da177e4SLinus Torvalds } 30681da177e4SLinus Torvalds 30692e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 30702e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 30711da177e4SLinus Torvalds { 30722ad94ae6SAl Viro int error; 30731da177e4SLinus Torvalds char *from; 30741da177e4SLinus Torvalds char *to; 30756902d925SDave Hansen struct dentry *dentry; 30766902d925SDave Hansen struct nameidata nd; 30771da177e4SLinus Torvalds 30781da177e4SLinus Torvalds from = getname(oldname); 30791da177e4SLinus Torvalds if (IS_ERR(from)) 30801da177e4SLinus Torvalds return PTR_ERR(from); 30812ad94ae6SAl Viro 30822ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 30832ad94ae6SAl Viro if (error) 30846902d925SDave Hansen goto out_putname; 30851da177e4SLinus Torvalds 30861da177e4SLinus Torvalds dentry = lookup_create(&nd, 0); 30871da177e4SLinus Torvalds error = PTR_ERR(dentry); 30886902d925SDave Hansen if (IS_ERR(dentry)) 30896902d925SDave Hansen goto out_unlock; 30906902d925SDave Hansen 309175c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 309275c3f29dSDave Hansen if (error) 309375c3f29dSDave Hansen goto out_dput; 3094be6d3e56SKentaro Takeda error = security_path_symlink(&nd.path, dentry, from); 3095be6d3e56SKentaro Takeda if (error) 3096be6d3e56SKentaro Takeda goto out_drop_write; 3097db2e747bSMiklos Szeredi error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); 3098be6d3e56SKentaro Takeda out_drop_write: 309975c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 310075c3f29dSDave Hansen out_dput: 31011da177e4SLinus Torvalds dput(dentry); 31026902d925SDave Hansen out_unlock: 31034ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 31041d957f9bSJan Blunck path_put(&nd.path); 31051da177e4SLinus Torvalds putname(to); 31066902d925SDave Hansen out_putname: 31071da177e4SLinus Torvalds putname(from); 31081da177e4SLinus Torvalds return error; 31091da177e4SLinus Torvalds } 31101da177e4SLinus Torvalds 31113480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 31125590ff0dSUlrich Drepper { 31135590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 31145590ff0dSUlrich Drepper } 31155590ff0dSUlrich Drepper 31161da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 31171da177e4SLinus Torvalds { 31181da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 31191da177e4SLinus Torvalds int error; 31201da177e4SLinus Torvalds 31211da177e4SLinus Torvalds if (!inode) 31221da177e4SLinus Torvalds return -ENOENT; 31231da177e4SLinus Torvalds 3124a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 31251da177e4SLinus Torvalds if (error) 31261da177e4SLinus Torvalds return error; 31271da177e4SLinus Torvalds 31281da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 31291da177e4SLinus Torvalds return -EXDEV; 31301da177e4SLinus Torvalds 31311da177e4SLinus Torvalds /* 31321da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 31331da177e4SLinus Torvalds */ 31341da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 31351da177e4SLinus Torvalds return -EPERM; 3136acfa4380SAl Viro if (!dir->i_op->link) 31371da177e4SLinus Torvalds return -EPERM; 31387e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 31391da177e4SLinus Torvalds return -EPERM; 31401da177e4SLinus Torvalds 31411da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 31421da177e4SLinus Torvalds if (error) 31431da177e4SLinus Torvalds return error; 31441da177e4SLinus Torvalds 31457e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 31461da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 31477e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3148e31e14ecSStephen Smalley if (!error) 31497e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 31501da177e4SLinus Torvalds return error; 31511da177e4SLinus Torvalds } 31521da177e4SLinus Torvalds 31531da177e4SLinus Torvalds /* 31541da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 31551da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 31561da177e4SLinus Torvalds * newname. --KAB 31571da177e4SLinus Torvalds * 31581da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 31591da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 31601da177e4SLinus Torvalds * and other special files. --ADM 31611da177e4SLinus Torvalds */ 31622e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 31632e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 31641da177e4SLinus Torvalds { 31651da177e4SLinus Torvalds struct dentry *new_dentry; 31662d8f3038SAl Viro struct nameidata nd; 31672d8f3038SAl Viro struct path old_path; 31681da177e4SLinus Torvalds int error; 31691da177e4SLinus Torvalds char *to; 31701da177e4SLinus Torvalds 317145c9b11aSUlrich Drepper if ((flags & ~AT_SYMLINK_FOLLOW) != 0) 3172c04030e1SUlrich Drepper return -EINVAL; 3173c04030e1SUlrich Drepper 31742d8f3038SAl Viro error = user_path_at(olddfd, oldname, 317545c9b11aSUlrich Drepper flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, 31762d8f3038SAl Viro &old_path); 31771da177e4SLinus Torvalds if (error) 31782ad94ae6SAl Viro return error; 31792ad94ae6SAl Viro 31802ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &nd, &to); 31811da177e4SLinus Torvalds if (error) 31821da177e4SLinus Torvalds goto out; 31831da177e4SLinus Torvalds error = -EXDEV; 31842d8f3038SAl Viro if (old_path.mnt != nd.path.mnt) 31851da177e4SLinus Torvalds goto out_release; 31861da177e4SLinus Torvalds new_dentry = lookup_create(&nd, 0); 31871da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31886902d925SDave Hansen if (IS_ERR(new_dentry)) 31896902d925SDave Hansen goto out_unlock; 319075c3f29dSDave Hansen error = mnt_want_write(nd.path.mnt); 319175c3f29dSDave Hansen if (error) 319275c3f29dSDave Hansen goto out_dput; 3193be6d3e56SKentaro Takeda error = security_path_link(old_path.dentry, &nd.path, new_dentry); 3194be6d3e56SKentaro Takeda if (error) 3195be6d3e56SKentaro Takeda goto out_drop_write; 31962d8f3038SAl Viro error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); 3197be6d3e56SKentaro Takeda out_drop_write: 319875c3f29dSDave Hansen mnt_drop_write(nd.path.mnt); 319975c3f29dSDave Hansen out_dput: 32001da177e4SLinus Torvalds dput(new_dentry); 32016902d925SDave Hansen out_unlock: 32024ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 32031da177e4SLinus Torvalds out_release: 32041d957f9bSJan Blunck path_put(&nd.path); 32052ad94ae6SAl Viro putname(to); 32061da177e4SLinus Torvalds out: 32072d8f3038SAl Viro path_put(&old_path); 32081da177e4SLinus Torvalds 32091da177e4SLinus Torvalds return error; 32101da177e4SLinus Torvalds } 32111da177e4SLinus Torvalds 32123480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 32135590ff0dSUlrich Drepper { 3214c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 32155590ff0dSUlrich Drepper } 32165590ff0dSUlrich Drepper 32171da177e4SLinus Torvalds /* 32181da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 32191da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 32201da177e4SLinus Torvalds * Problems: 32211da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 32221da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 32231da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3224a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 32251da177e4SLinus Torvalds * story. 32261da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 32271b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 32281da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 32291da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3230a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 32311da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 32321da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 32331da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3234a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 32351da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 32361da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 32371da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 32381da177e4SLinus Torvalds * d) some filesystems don't support opened-but-unlinked directories, 32391da177e4SLinus Torvalds * either because of layout or because they are not ready to deal with 32401da177e4SLinus Torvalds * all cases correctly. The latter will be fixed (taking this sort of 32411da177e4SLinus Torvalds * stuff into VFS), but the former is not going away. Solution: the same 32421da177e4SLinus Torvalds * trick as in rmdir(). 32431da177e4SLinus Torvalds * e) conversion from fhandle to dentry may come in the wrong moment - when 32441b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 32451da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3246c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 32471da177e4SLinus Torvalds * locking]. 32481da177e4SLinus Torvalds */ 324975c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 32501da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32511da177e4SLinus Torvalds { 32521da177e4SLinus Torvalds int error = 0; 32531da177e4SLinus Torvalds struct inode *target; 32541da177e4SLinus Torvalds 32551da177e4SLinus Torvalds /* 32561da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 32571da177e4SLinus Torvalds * we'll need to flip '..'. 32581da177e4SLinus Torvalds */ 32591da177e4SLinus Torvalds if (new_dir != old_dir) { 3260f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 32611da177e4SLinus Torvalds if (error) 32621da177e4SLinus Torvalds return error; 32631da177e4SLinus Torvalds } 32641da177e4SLinus Torvalds 32651da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 32661da177e4SLinus Torvalds if (error) 32671da177e4SLinus Torvalds return error; 32681da177e4SLinus Torvalds 32691da177e4SLinus Torvalds target = new_dentry->d_inode; 3270d83c49f3SAl Viro if (target) 32711b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 32721da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 32731da177e4SLinus Torvalds error = -EBUSY; 3274d83c49f3SAl Viro else { 3275d83c49f3SAl Viro if (target) 3276d83c49f3SAl Viro dentry_unhash(new_dentry); 32771da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 3278d83c49f3SAl Viro } 32791da177e4SLinus Torvalds if (target) { 3280d83c49f3SAl Viro if (!error) { 32811da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3282d83c49f3SAl Viro dont_mount(new_dentry); 3283d83c49f3SAl Viro } 32841b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 32851da177e4SLinus Torvalds if (d_unhashed(new_dentry)) 32861da177e4SLinus Torvalds d_rehash(new_dentry); 32871da177e4SLinus Torvalds dput(new_dentry); 32881da177e4SLinus Torvalds } 3289e31e14ecSStephen Smalley if (!error) 3290349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 32911da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 32921da177e4SLinus Torvalds return error; 32931da177e4SLinus Torvalds } 32941da177e4SLinus Torvalds 329575c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 32961da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32971da177e4SLinus Torvalds { 32981da177e4SLinus Torvalds struct inode *target; 32991da177e4SLinus Torvalds int error; 33001da177e4SLinus Torvalds 33011da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 33021da177e4SLinus Torvalds if (error) 33031da177e4SLinus Torvalds return error; 33041da177e4SLinus Torvalds 33051da177e4SLinus Torvalds dget(new_dentry); 33061da177e4SLinus Torvalds target = new_dentry->d_inode; 33071da177e4SLinus Torvalds if (target) 33081b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 33091da177e4SLinus Torvalds if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 33101da177e4SLinus Torvalds error = -EBUSY; 33111da177e4SLinus Torvalds else 33121da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 33131da177e4SLinus Torvalds if (!error) { 3314bec1052eSAl Viro if (target) 3315d83c49f3SAl Viro dont_mount(new_dentry); 3316349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 33171da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 33181da177e4SLinus Torvalds } 33191da177e4SLinus Torvalds if (target) 33201b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 33211da177e4SLinus Torvalds dput(new_dentry); 33221da177e4SLinus Torvalds return error; 33231da177e4SLinus Torvalds } 33241da177e4SLinus Torvalds 33251da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 33261da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 33271da177e4SLinus Torvalds { 33281da177e4SLinus Torvalds int error; 33291da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 333059b0df21SEric Paris const unsigned char *old_name; 33311da177e4SLinus Torvalds 33321da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 33331da177e4SLinus Torvalds return 0; 33341da177e4SLinus Torvalds 33351da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 33361da177e4SLinus Torvalds if (error) 33371da177e4SLinus Torvalds return error; 33381da177e4SLinus Torvalds 33391da177e4SLinus Torvalds if (!new_dentry->d_inode) 3340a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 33411da177e4SLinus Torvalds else 33421da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 33431da177e4SLinus Torvalds if (error) 33441da177e4SLinus Torvalds return error; 33451da177e4SLinus Torvalds 3346acfa4380SAl Viro if (!old_dir->i_op->rename) 33471da177e4SLinus Torvalds return -EPERM; 33481da177e4SLinus Torvalds 33490eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 33500eeca283SRobert Love 33511da177e4SLinus Torvalds if (is_dir) 33521da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 33531da177e4SLinus Torvalds else 33541da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3355123df294SAl Viro if (!error) 3356123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 33575a190ae6SAl Viro new_dentry->d_inode, old_dentry); 33580eeca283SRobert Love fsnotify_oldname_free(old_name); 33590eeca283SRobert Love 33601da177e4SLinus Torvalds return error; 33611da177e4SLinus Torvalds } 33621da177e4SLinus Torvalds 33632e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 33642e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 33651da177e4SLinus Torvalds { 33661da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 33671da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 33681da177e4SLinus Torvalds struct dentry *trap; 33691da177e4SLinus Torvalds struct nameidata oldnd, newnd; 33702ad94ae6SAl Viro char *from; 33712ad94ae6SAl Viro char *to; 33722ad94ae6SAl Viro int error; 33731da177e4SLinus Torvalds 33742ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 33751da177e4SLinus Torvalds if (error) 33761da177e4SLinus Torvalds goto exit; 33771da177e4SLinus Torvalds 33782ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 33791da177e4SLinus Torvalds if (error) 33801da177e4SLinus Torvalds goto exit1; 33811da177e4SLinus Torvalds 33821da177e4SLinus Torvalds error = -EXDEV; 33834ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 33841da177e4SLinus Torvalds goto exit2; 33851da177e4SLinus Torvalds 33864ac91378SJan Blunck old_dir = oldnd.path.dentry; 33871da177e4SLinus Torvalds error = -EBUSY; 33881da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 33891da177e4SLinus Torvalds goto exit2; 33901da177e4SLinus Torvalds 33914ac91378SJan Blunck new_dir = newnd.path.dentry; 33921da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 33931da177e4SLinus Torvalds goto exit2; 33941da177e4SLinus Torvalds 33950612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 33960612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 33974e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 33980612d9fbSOGAWA Hirofumi 33991da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 34001da177e4SLinus Torvalds 340149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 34021da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 34031da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 34041da177e4SLinus Torvalds goto exit3; 34051da177e4SLinus Torvalds /* source must exist */ 34061da177e4SLinus Torvalds error = -ENOENT; 34071da177e4SLinus Torvalds if (!old_dentry->d_inode) 34081da177e4SLinus Torvalds goto exit4; 34091da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 34101da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 34111da177e4SLinus Torvalds error = -ENOTDIR; 34121da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 34131da177e4SLinus Torvalds goto exit4; 34141da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 34151da177e4SLinus Torvalds goto exit4; 34161da177e4SLinus Torvalds } 34171da177e4SLinus Torvalds /* source should not be ancestor of target */ 34181da177e4SLinus Torvalds error = -EINVAL; 34191da177e4SLinus Torvalds if (old_dentry == trap) 34201da177e4SLinus Torvalds goto exit4; 342149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 34221da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 34231da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 34241da177e4SLinus Torvalds goto exit4; 34251da177e4SLinus Torvalds /* target should not be an ancestor of source */ 34261da177e4SLinus Torvalds error = -ENOTEMPTY; 34271da177e4SLinus Torvalds if (new_dentry == trap) 34281da177e4SLinus Torvalds goto exit5; 34291da177e4SLinus Torvalds 34309079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 34319079b1ebSDave Hansen if (error) 34329079b1ebSDave Hansen goto exit5; 3433be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3434be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3435be6d3e56SKentaro Takeda if (error) 3436be6d3e56SKentaro Takeda goto exit6; 34371da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 34381da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3439be6d3e56SKentaro Takeda exit6: 34409079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 34411da177e4SLinus Torvalds exit5: 34421da177e4SLinus Torvalds dput(new_dentry); 34431da177e4SLinus Torvalds exit4: 34441da177e4SLinus Torvalds dput(old_dentry); 34451da177e4SLinus Torvalds exit3: 34461da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 34471da177e4SLinus Torvalds exit2: 34481d957f9bSJan Blunck path_put(&newnd.path); 34492ad94ae6SAl Viro putname(to); 34501da177e4SLinus Torvalds exit1: 34511d957f9bSJan Blunck path_put(&oldnd.path); 34521da177e4SLinus Torvalds putname(from); 34532ad94ae6SAl Viro exit: 34541da177e4SLinus Torvalds return error; 34551da177e4SLinus Torvalds } 34561da177e4SLinus Torvalds 3457a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 34585590ff0dSUlrich Drepper { 34595590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 34605590ff0dSUlrich Drepper } 34615590ff0dSUlrich Drepper 34621da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 34631da177e4SLinus Torvalds { 34641da177e4SLinus Torvalds int len; 34651da177e4SLinus Torvalds 34661da177e4SLinus Torvalds len = PTR_ERR(link); 34671da177e4SLinus Torvalds if (IS_ERR(link)) 34681da177e4SLinus Torvalds goto out; 34691da177e4SLinus Torvalds 34701da177e4SLinus Torvalds len = strlen(link); 34711da177e4SLinus Torvalds if (len > (unsigned) buflen) 34721da177e4SLinus Torvalds len = buflen; 34731da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 34741da177e4SLinus Torvalds len = -EFAULT; 34751da177e4SLinus Torvalds out: 34761da177e4SLinus Torvalds return len; 34771da177e4SLinus Torvalds } 34781da177e4SLinus Torvalds 34791da177e4SLinus Torvalds /* 34801da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 34811da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 34821da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 34831da177e4SLinus Torvalds */ 34841da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 34851da177e4SLinus Torvalds { 34861da177e4SLinus Torvalds struct nameidata nd; 3487cc314eefSLinus Torvalds void *cookie; 3488694a1764SMarcin Slusarz int res; 3489cc314eefSLinus Torvalds 34901da177e4SLinus Torvalds nd.depth = 0; 3491cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3492694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3493694a1764SMarcin Slusarz return PTR_ERR(cookie); 3494694a1764SMarcin Slusarz 3495694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 34961da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3497cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3498694a1764SMarcin Slusarz return res; 34991da177e4SLinus Torvalds } 35001da177e4SLinus Torvalds 35011da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 35021da177e4SLinus Torvalds { 35031da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 35041da177e4SLinus Torvalds } 35051da177e4SLinus Torvalds 35061da177e4SLinus Torvalds /* get the link contents into pagecache */ 35071da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 35081da177e4SLinus Torvalds { 3509ebd09abbSDuane Griffin char *kaddr; 35101da177e4SLinus Torvalds struct page *page; 35111da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3512090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 35131da177e4SLinus Torvalds if (IS_ERR(page)) 35146fe6900eSNick Piggin return (char*)page; 35151da177e4SLinus Torvalds *ppage = page; 3516ebd09abbSDuane Griffin kaddr = kmap(page); 3517ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3518ebd09abbSDuane Griffin return kaddr; 35191da177e4SLinus Torvalds } 35201da177e4SLinus Torvalds 35211da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 35221da177e4SLinus Torvalds { 35231da177e4SLinus Torvalds struct page *page = NULL; 35241da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 35251da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 35261da177e4SLinus Torvalds if (page) { 35271da177e4SLinus Torvalds kunmap(page); 35281da177e4SLinus Torvalds page_cache_release(page); 35291da177e4SLinus Torvalds } 35301da177e4SLinus Torvalds return res; 35311da177e4SLinus Torvalds } 35321da177e4SLinus Torvalds 3533cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 35341da177e4SLinus Torvalds { 3535cc314eefSLinus Torvalds struct page *page = NULL; 35361da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3537cc314eefSLinus Torvalds return page; 35381da177e4SLinus Torvalds } 35391da177e4SLinus Torvalds 3540cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 35411da177e4SLinus Torvalds { 3542cc314eefSLinus Torvalds struct page *page = cookie; 3543cc314eefSLinus Torvalds 3544cc314eefSLinus Torvalds if (page) { 35451da177e4SLinus Torvalds kunmap(page); 35461da177e4SLinus Torvalds page_cache_release(page); 35471da177e4SLinus Torvalds } 35481da177e4SLinus Torvalds } 35491da177e4SLinus Torvalds 355054566b2cSNick Piggin /* 355154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 355254566b2cSNick Piggin */ 355354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 35541da177e4SLinus Torvalds { 35551da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 35560adb25d2SKirill Korotaev struct page *page; 3557afddba49SNick Piggin void *fsdata; 3558beb497abSDmitriy Monakhov int err; 35591da177e4SLinus Torvalds char *kaddr; 356054566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 356154566b2cSNick Piggin if (nofs) 356254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 35631da177e4SLinus Torvalds 35647e53cac4SNeilBrown retry: 3565afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 356654566b2cSNick Piggin flags, &page, &fsdata); 35671da177e4SLinus Torvalds if (err) 3568afddba49SNick Piggin goto fail; 3569afddba49SNick Piggin 35701da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 35711da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 35721da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3573afddba49SNick Piggin 3574afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3575afddba49SNick Piggin page, fsdata); 35761da177e4SLinus Torvalds if (err < 0) 35771da177e4SLinus Torvalds goto fail; 3578afddba49SNick Piggin if (err < len-1) 3579afddba49SNick Piggin goto retry; 3580afddba49SNick Piggin 35811da177e4SLinus Torvalds mark_inode_dirty(inode); 35821da177e4SLinus Torvalds return 0; 35831da177e4SLinus Torvalds fail: 35841da177e4SLinus Torvalds return err; 35851da177e4SLinus Torvalds } 35861da177e4SLinus Torvalds 35870adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 35880adb25d2SKirill Korotaev { 35890adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 359054566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 35910adb25d2SKirill Korotaev } 35920adb25d2SKirill Korotaev 359392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 35941da177e4SLinus Torvalds .readlink = generic_readlink, 35951da177e4SLinus Torvalds .follow_link = page_follow_link_light, 35961da177e4SLinus Torvalds .put_link = page_put_link, 35971da177e4SLinus Torvalds }; 35981da177e4SLinus Torvalds 35992d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3600cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 36011da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 36021da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 36031da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 36041da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 36051da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 36061da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 36071da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 36081da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 36091da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 36100adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 36111da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 36121da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 36131da177e4SLinus Torvalds EXPORT_SYMBOL(path_lookup); 3614d1811465SAl Viro EXPORT_SYMBOL(kern_path); 361516f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3616f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 36178c744fb8SChristoph Hellwig EXPORT_SYMBOL(file_permission); 36181da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 36191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 36201da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 36211da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 36221da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 36231da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 36241da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 36251da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 36261da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 36271da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 36281da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 36291da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 36301da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 36311da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3632