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> 18630d9c47SPaul Gortmaker #include <linux/export.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> 35e77819e5SLinus Torvalds #include <linux/posix_acl.h> 361da177e4SLinus Torvalds #include <asm/uaccess.h> 371da177e4SLinus Torvalds 38e81e3f4dSEric Paris #include "internal.h" 39c7105365SAl Viro #include "mount.h" 40e81e3f4dSEric Paris 411da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 421da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 431da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 441da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 451da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 461da177e4SLinus Torvalds * 471da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 481da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 491da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 501da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 511da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 521da177e4SLinus Torvalds * the special cases of the former code. 531da177e4SLinus Torvalds * 541da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 551da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 561da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 571da177e4SLinus Torvalds * 581da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 591da177e4SLinus Torvalds * resolution to correspond with current state of the code. 601da177e4SLinus Torvalds * 611da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 621da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 631da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 641da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 651da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 661da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 671da177e4SLinus Torvalds */ 681da177e4SLinus Torvalds 691da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 701da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 711da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 721da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 731da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 741da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7525985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 761da177e4SLinus Torvalds * 771da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 781da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 791da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 801da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 811da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 821da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 831da177e4SLinus Torvalds * and in the old Linux semantics. 841da177e4SLinus Torvalds */ 851da177e4SLinus Torvalds 861da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 871da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 881da177e4SLinus Torvalds * 891da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 901da177e4SLinus Torvalds */ 911da177e4SLinus Torvalds 921da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 931da177e4SLinus Torvalds * inside the path - always follow. 941da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 951da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 961da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 971da177e4SLinus Torvalds * otherwise - don't follow. 981da177e4SLinus Torvalds * (applied in that order). 991da177e4SLinus Torvalds * 1001da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1011da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1021da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1031da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1041da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1051da177e4SLinus Torvalds */ 1061da177e4SLinus Torvalds /* 1071da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 108a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1091da177e4SLinus Torvalds * any extra contention... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds 1121da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1131da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1141da177e4SLinus Torvalds * kernel data space before using them.. 1151da177e4SLinus Torvalds * 1161da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1171da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1181da177e4SLinus Torvalds */ 119858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1201da177e4SLinus Torvalds { 1211da177e4SLinus Torvalds int retval; 1221da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1231da177e4SLinus Torvalds 1241da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1251da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1261da177e4SLinus Torvalds return -EFAULT; 1271da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1281da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1291da177e4SLinus Torvalds } 1301da177e4SLinus Torvalds 1311da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1321da177e4SLinus Torvalds if (retval > 0) { 1331da177e4SLinus Torvalds if (retval < len) 1341da177e4SLinus Torvalds return 0; 1351da177e4SLinus Torvalds return -ENAMETOOLONG; 1361da177e4SLinus Torvalds } else if (!retval) 1371da177e4SLinus Torvalds retval = -ENOENT; 1381da177e4SLinus Torvalds return retval; 1391da177e4SLinus Torvalds } 1401da177e4SLinus Torvalds 1411fa1e7f6SAndy Whitcroft static char *getname_flags(const char __user *filename, int flags, int *empty) 1421da177e4SLinus Torvalds { 1434043cde8SEric Paris char *result = __getname(); 1444043cde8SEric Paris int retval; 1451da177e4SLinus Torvalds 1464043cde8SEric Paris if (!result) 1474043cde8SEric Paris return ERR_PTR(-ENOMEM); 1481da177e4SLinus Torvalds 1494043cde8SEric Paris retval = do_getname(filename, result); 1501da177e4SLinus Torvalds if (retval < 0) { 1511fa1e7f6SAndy Whitcroft if (retval == -ENOENT && empty) 1521fa1e7f6SAndy Whitcroft *empty = 1; 153f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1544043cde8SEric Paris __putname(result); 1554043cde8SEric Paris return ERR_PTR(retval); 1561da177e4SLinus Torvalds } 157f52e0c11SAl Viro } 1581da177e4SLinus Torvalds audit_getname(result); 1591da177e4SLinus Torvalds return result; 1601da177e4SLinus Torvalds } 1611da177e4SLinus Torvalds 162f52e0c11SAl Viro char *getname(const char __user * filename) 163f52e0c11SAl Viro { 164f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 165f52e0c11SAl Viro } 166f52e0c11SAl Viro 1671da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1681da177e4SLinus Torvalds void putname(const char *name) 1691da177e4SLinus Torvalds { 1705ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1711da177e4SLinus Torvalds audit_putname(name); 1721da177e4SLinus Torvalds else 1731da177e4SLinus Torvalds __putname(name); 1741da177e4SLinus Torvalds } 1751da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1761da177e4SLinus Torvalds #endif 1771da177e4SLinus Torvalds 178e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 179e77819e5SLinus Torvalds { 18084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 181e77819e5SLinus Torvalds struct posix_acl *acl; 182e77819e5SLinus Torvalds 183e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 1843567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 1853567866bSAl Viro if (!acl) 186e77819e5SLinus Torvalds return -EAGAIN; 1873567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 1883567866bSAl Viro if (acl == ACL_NOT_CACHED) 189e77819e5SLinus Torvalds return -ECHILD; 190206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 191e77819e5SLinus Torvalds } 192e77819e5SLinus Torvalds 193e77819e5SLinus Torvalds acl = get_cached_acl(inode, ACL_TYPE_ACCESS); 194e77819e5SLinus Torvalds 195e77819e5SLinus Torvalds /* 1964e34e719SChristoph Hellwig * A filesystem can force a ACL callback by just never filling the 1974e34e719SChristoph Hellwig * ACL cache. But normally you'd fill the cache either at inode 1984e34e719SChristoph Hellwig * instantiation time, or on the first ->get_acl call. 199e77819e5SLinus Torvalds * 2004e34e719SChristoph Hellwig * If the filesystem doesn't have a get_acl() function at all, we'll 2014e34e719SChristoph Hellwig * just create the negative cache entry. 202e77819e5SLinus Torvalds */ 203e77819e5SLinus Torvalds if (acl == ACL_NOT_CACHED) { 2044e34e719SChristoph Hellwig if (inode->i_op->get_acl) { 2054e34e719SChristoph Hellwig acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); 2064e34e719SChristoph Hellwig if (IS_ERR(acl)) 2074e34e719SChristoph Hellwig return PTR_ERR(acl); 2084e34e719SChristoph Hellwig } else { 209e77819e5SLinus Torvalds set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); 210e77819e5SLinus Torvalds return -EAGAIN; 211e77819e5SLinus Torvalds } 2124e34e719SChristoph Hellwig } 213e77819e5SLinus Torvalds 214e77819e5SLinus Torvalds if (acl) { 215e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 216e77819e5SLinus Torvalds posix_acl_release(acl); 217e77819e5SLinus Torvalds return error; 218e77819e5SLinus Torvalds } 21984635d68SLinus Torvalds #endif 220e77819e5SLinus Torvalds 221e77819e5SLinus Torvalds return -EAGAIN; 222e77819e5SLinus Torvalds } 223e77819e5SLinus Torvalds 2245909ccaaSLinus Torvalds /* 225948409c7SAndreas Gruenbacher * This does the basic permission checking 2265909ccaaSLinus Torvalds */ 2277e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2285909ccaaSLinus Torvalds { 22926cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2305909ccaaSLinus Torvalds 2318e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2325909ccaaSLinus Torvalds mode >>= 6; 2335909ccaaSLinus Torvalds else { 234e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2357e40145eSAl Viro int error = check_acl(inode, mask); 2365909ccaaSLinus Torvalds if (error != -EAGAIN) 2375909ccaaSLinus Torvalds return error; 2385909ccaaSLinus Torvalds } 2395909ccaaSLinus Torvalds 2405909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2415909ccaaSLinus Torvalds mode >>= 3; 2425909ccaaSLinus Torvalds } 2435909ccaaSLinus Torvalds 2445909ccaaSLinus Torvalds /* 2455909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2465909ccaaSLinus Torvalds */ 2479c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2485909ccaaSLinus Torvalds return 0; 2495909ccaaSLinus Torvalds return -EACCES; 2505909ccaaSLinus Torvalds } 2511da177e4SLinus Torvalds 2521da177e4SLinus Torvalds /** 2531da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2541da177e4SLinus Torvalds * @inode: inode to check access rights for 2558fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 2561da177e4SLinus Torvalds * 2571da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2581da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2591da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 260b74c79e9SNick Piggin * are used for other things. 261b74c79e9SNick Piggin * 262b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 263b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 264b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2651da177e4SLinus Torvalds */ 2662830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2671da177e4SLinus Torvalds { 2685909ccaaSLinus Torvalds int ret; 2691da177e4SLinus Torvalds 2701da177e4SLinus Torvalds /* 271948409c7SAndreas Gruenbacher * Do the basic permission checks. 2721da177e4SLinus Torvalds */ 2737e40145eSAl Viro ret = acl_permission_check(inode, mask); 2745909ccaaSLinus Torvalds if (ret != -EACCES) 2755909ccaaSLinus Torvalds return ret; 2761da177e4SLinus Torvalds 277d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 278d594e7ecSAl Viro /* DACs are overridable for directories */ 2791a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 280d594e7ecSAl Viro return 0; 281d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 2821a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 283d594e7ecSAl Viro return 0; 284d594e7ecSAl Viro return -EACCES; 285d594e7ecSAl Viro } 2861da177e4SLinus Torvalds /* 2871da177e4SLinus Torvalds * Read/write DACs are always overridable. 288d594e7ecSAl Viro * Executable DACs are overridable when there is 289d594e7ecSAl Viro * at least one exec bit set. 2901da177e4SLinus Torvalds */ 291d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 2921a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 2931da177e4SLinus Torvalds return 0; 2941da177e4SLinus Torvalds 2951da177e4SLinus Torvalds /* 2961da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 2971da177e4SLinus Torvalds */ 2987ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 299d594e7ecSAl Viro if (mask == MAY_READ) 3001a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 3011da177e4SLinus Torvalds return 0; 3021da177e4SLinus Torvalds 3031da177e4SLinus Torvalds return -EACCES; 3041da177e4SLinus Torvalds } 3051da177e4SLinus Torvalds 3063ddcd056SLinus Torvalds /* 3073ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3083ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3093ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3103ddcd056SLinus Torvalds * permission function, use the fast case". 3113ddcd056SLinus Torvalds */ 3123ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3133ddcd056SLinus Torvalds { 3143ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3153ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3163ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3173ddcd056SLinus Torvalds 3183ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3193ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3203ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3213ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3223ddcd056SLinus Torvalds } 3233ddcd056SLinus Torvalds return generic_permission(inode, mask); 3243ddcd056SLinus Torvalds } 3253ddcd056SLinus Torvalds 326cb23beb5SChristoph Hellwig /** 327cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 328cb23beb5SChristoph Hellwig * @inode: inode to check permission on 3298fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 330cb23beb5SChristoph Hellwig * 331cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 332cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 333cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 334cb23beb5SChristoph Hellwig * are used for other things. 335948409c7SAndreas Gruenbacher * 336948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 337cb23beb5SChristoph Hellwig */ 338f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 3391da177e4SLinus Torvalds { 340e6305c43SAl Viro int retval; 3411da177e4SLinus Torvalds 3423ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 34322590e41SMiklos Szeredi umode_t mode = inode->i_mode; 3441da177e4SLinus Torvalds 3451da177e4SLinus Torvalds /* 3461da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 3471da177e4SLinus Torvalds */ 3481da177e4SLinus Torvalds if (IS_RDONLY(inode) && 3491da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 3501da177e4SLinus Torvalds return -EROFS; 3511da177e4SLinus Torvalds 3521da177e4SLinus Torvalds /* 3531da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3541da177e4SLinus Torvalds */ 3551da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3561da177e4SLinus Torvalds return -EACCES; 3571da177e4SLinus Torvalds } 3581da177e4SLinus Torvalds 3593ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3601da177e4SLinus Torvalds if (retval) 3611da177e4SLinus Torvalds return retval; 3621da177e4SLinus Torvalds 36308ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 36408ce5f16SSerge E. Hallyn if (retval) 36508ce5f16SSerge E. Hallyn return retval; 36608ce5f16SSerge E. Hallyn 367d09ca739SEric Paris return security_inode_permission(inode, mask); 3681da177e4SLinus Torvalds } 3691da177e4SLinus Torvalds 370f4d6ff89SAl Viro /** 3715dd784d0SJan Blunck * path_get - get a reference to a path 3725dd784d0SJan Blunck * @path: path to get the reference to 3735dd784d0SJan Blunck * 3745dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3755dd784d0SJan Blunck */ 3765dd784d0SJan Blunck void path_get(struct path *path) 3775dd784d0SJan Blunck { 3785dd784d0SJan Blunck mntget(path->mnt); 3795dd784d0SJan Blunck dget(path->dentry); 3805dd784d0SJan Blunck } 3815dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3825dd784d0SJan Blunck 3835dd784d0SJan Blunck /** 3841d957f9bSJan Blunck * path_put - put a reference to a path 3851d957f9bSJan Blunck * @path: path to put the reference to 3861d957f9bSJan Blunck * 3871d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3881d957f9bSJan Blunck */ 3891d957f9bSJan Blunck void path_put(struct path *path) 3901da177e4SLinus Torvalds { 3911d957f9bSJan Blunck dput(path->dentry); 3921d957f9bSJan Blunck mntput(path->mnt); 3931da177e4SLinus Torvalds } 3941d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3951da177e4SLinus Torvalds 39619660af7SAl Viro /* 39731e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 39819660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 39919660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 40019660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 40119660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 40219660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 40319660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 40419660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 40531e6b01fSNick Piggin */ 40631e6b01fSNick Piggin 40731e6b01fSNick Piggin /** 40819660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 40919660af7SAl Viro * @nd: nameidata pathwalk data 41019660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 41139191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 41231e6b01fSNick Piggin * 41319660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 41419660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 41519660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 41631e6b01fSNick Piggin */ 41719660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 41831e6b01fSNick Piggin { 41931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 42031e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4215b6ca027SAl Viro int want_root = 0; 42231e6b01fSNick Piggin 42331e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4245b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4255b6ca027SAl Viro want_root = 1; 42631e6b01fSNick Piggin spin_lock(&fs->lock); 42731e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 42831e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 42931e6b01fSNick Piggin goto err_root; 43031e6b01fSNick Piggin } 43131e6b01fSNick Piggin spin_lock(&parent->d_lock); 43219660af7SAl Viro if (!dentry) { 43319660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 43419660af7SAl Viro goto err_parent; 43519660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 43619660af7SAl Viro } else { 43794c0d4ecSAl Viro if (dentry->d_parent != parent) 43894c0d4ecSAl Viro goto err_parent; 43931e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 44031e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 44119660af7SAl Viro goto err_child; 44231e6b01fSNick Piggin /* 44319660af7SAl Viro * If the sequence check on the child dentry passed, then 44419660af7SAl Viro * the child has not been removed from its parent. This 44519660af7SAl Viro * means the parent dentry must be valid and able to take 44619660af7SAl Viro * a reference at this point. 44731e6b01fSNick Piggin */ 44831e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 44931e6b01fSNick Piggin BUG_ON(!parent->d_count); 45031e6b01fSNick Piggin parent->d_count++; 45131e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 45219660af7SAl Viro } 45331e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4545b6ca027SAl Viro if (want_root) { 45531e6b01fSNick Piggin path_get(&nd->root); 45631e6b01fSNick Piggin spin_unlock(&fs->lock); 45731e6b01fSNick Piggin } 45831e6b01fSNick Piggin mntget(nd->path.mnt); 45931e6b01fSNick Piggin 46031e6b01fSNick Piggin rcu_read_unlock(); 46131e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 46231e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 46331e6b01fSNick Piggin return 0; 46419660af7SAl Viro 46519660af7SAl Viro err_child: 46631e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 46719660af7SAl Viro err_parent: 46831e6b01fSNick Piggin spin_unlock(&parent->d_lock); 46931e6b01fSNick Piggin err_root: 4705b6ca027SAl Viro if (want_root) 47131e6b01fSNick Piggin spin_unlock(&fs->lock); 47231e6b01fSNick Piggin return -ECHILD; 47331e6b01fSNick Piggin } 47431e6b01fSNick Piggin 47531e6b01fSNick Piggin /** 476834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 477834f2a4aSTrond Myklebust * @nd: pointer to nameidata 478834f2a4aSTrond Myklebust */ 479834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 480834f2a4aSTrond Myklebust { 4812dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4822dab5974SLinus Torvalds 4832dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4842dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4852dab5974SLinus Torvalds put_filp(file); 486834f2a4aSTrond Myklebust else 4872dab5974SLinus Torvalds fput(file); 4882dab5974SLinus Torvalds } 489834f2a4aSTrond Myklebust } 490834f2a4aSTrond Myklebust 491f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 49234286d66SNick Piggin { 493f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 49434286d66SNick Piggin } 49534286d66SNick Piggin 4969f1fafeeSAl Viro /** 4979f1fafeeSAl Viro * complete_walk - successful completion of path walk 4989f1fafeeSAl Viro * @nd: pointer nameidata 49939159de2SJeff Layton * 5009f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5019f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5029f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5039f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5049f1fafeeSAl Viro * need to drop nd->path. 50539159de2SJeff Layton */ 5069f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 50739159de2SJeff Layton { 50816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 50939159de2SJeff Layton int status; 51039159de2SJeff Layton 5119f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5129f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5139f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5149f1fafeeSAl Viro nd->root.mnt = NULL; 5159f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5169f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5179f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5189f1fafeeSAl Viro rcu_read_unlock(); 5199f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5209f1fafeeSAl Viro return -ECHILD; 5219f1fafeeSAl Viro } 5229f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5239f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5249f1fafeeSAl Viro mntget(nd->path.mnt); 5259f1fafeeSAl Viro rcu_read_unlock(); 5269f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5279f1fafeeSAl Viro } 5289f1fafeeSAl Viro 52916c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 53039159de2SJeff Layton return 0; 53139159de2SJeff Layton 53216c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 53316c2cd71SAl Viro return 0; 53416c2cd71SAl Viro 53516c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 53616c2cd71SAl Viro return 0; 53716c2cd71SAl Viro 53816c2cd71SAl Viro /* Note: we do not d_invalidate() */ 53934286d66SNick Piggin status = d_revalidate(dentry, nd); 54039159de2SJeff Layton if (status > 0) 54139159de2SJeff Layton return 0; 54239159de2SJeff Layton 54316c2cd71SAl Viro if (!status) 54439159de2SJeff Layton status = -ESTALE; 54516c2cd71SAl Viro 5469f1fafeeSAl Viro path_put(&nd->path); 54739159de2SJeff Layton return status; 54839159de2SJeff Layton } 54939159de2SJeff Layton 5502a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5512a737871SAl Viro { 552f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 553f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5542a737871SAl Viro } 5552a737871SAl Viro 5566de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5576de88d72SAl Viro 55831e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 55931e6b01fSNick Piggin { 56031e6b01fSNick Piggin if (!nd->root.mnt) { 56131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 562c28cc364SNick Piggin unsigned seq; 563c28cc364SNick Piggin 564c28cc364SNick Piggin do { 565c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 56631e6b01fSNick Piggin nd->root = fs->root; 567c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 568c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 56931e6b01fSNick Piggin } 57031e6b01fSNick Piggin } 57131e6b01fSNick Piggin 572f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5731da177e4SLinus Torvalds { 57431e6b01fSNick Piggin int ret; 57531e6b01fSNick Piggin 5761da177e4SLinus Torvalds if (IS_ERR(link)) 5771da177e4SLinus Torvalds goto fail; 5781da177e4SLinus Torvalds 5791da177e4SLinus Torvalds if (*link == '/') { 5802a737871SAl Viro set_root(nd); 5811d957f9bSJan Blunck path_put(&nd->path); 5822a737871SAl Viro nd->path = nd->root; 5832a737871SAl Viro path_get(&nd->root); 58416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 5851da177e4SLinus Torvalds } 58631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 587b4091d5fSChristoph Hellwig 58831e6b01fSNick Piggin ret = link_path_walk(link, nd); 58931e6b01fSNick Piggin return ret; 5901da177e4SLinus Torvalds fail: 5911d957f9bSJan Blunck path_put(&nd->path); 5921da177e4SLinus Torvalds return PTR_ERR(link); 5931da177e4SLinus Torvalds } 5941da177e4SLinus Torvalds 5951d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 596051d3812SIan Kent { 597051d3812SIan Kent dput(path->dentry); 5984ac91378SJan Blunck if (path->mnt != nd->path.mnt) 599051d3812SIan Kent mntput(path->mnt); 600051d3812SIan Kent } 601051d3812SIan Kent 6027b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6037b9337aaSNick Piggin struct nameidata *nd) 604051d3812SIan Kent { 60531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6064ac91378SJan Blunck dput(nd->path.dentry); 60731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6084ac91378SJan Blunck mntput(nd->path.mnt); 6099a229683SHuang Shijie } 61031e6b01fSNick Piggin nd->path.mnt = path->mnt; 6114ac91378SJan Blunck nd->path.dentry = path->dentry; 612051d3812SIan Kent } 613051d3812SIan Kent 614574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 615574197e0SAl Viro { 616574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 617574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 618574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 619574197e0SAl Viro path_put(link); 620574197e0SAl Viro } 621574197e0SAl Viro 622def4af30SAl Viro static __always_inline int 623574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6241da177e4SLinus Torvalds { 6251da177e4SLinus Torvalds int error; 6267b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6271da177e4SLinus Torvalds 628844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 629844a3917SAl Viro 6300e794589SAl Viro if (link->mnt == nd->path.mnt) 6310e794589SAl Viro mntget(link->mnt); 6320e794589SAl Viro 633574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 634574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 635574197e0SAl Viro path_put(&nd->path); 636574197e0SAl Viro return -ELOOP; 637574197e0SAl Viro } 638574197e0SAl Viro cond_resched(); 639574197e0SAl Viro current->total_link_count++; 640574197e0SAl Viro 64168ac1234SAl Viro touch_atime(link); 6421da177e4SLinus Torvalds nd_set_link(nd, NULL); 643cd4e91d3SAl Viro 64436f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 64536f3b4f6SAl Viro if (error) { 64636f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 64736f3b4f6SAl Viro path_put(&nd->path); 64836f3b4f6SAl Viro return error; 64936f3b4f6SAl Viro } 65036f3b4f6SAl Viro 65186acdca1SAl Viro nd->last_type = LAST_BIND; 652def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 653def4af30SAl Viro error = PTR_ERR(*p); 654def4af30SAl Viro if (!IS_ERR(*p)) { 6551da177e4SLinus Torvalds char *s = nd_get_link(nd); 656cc314eefSLinus Torvalds error = 0; 6571da177e4SLinus Torvalds if (s) 6581da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 659bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 66016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 661b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 662b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 663bcda7652SAl Viro /* stepped on a _really_ weird one */ 664bcda7652SAl Viro path_put(&nd->path); 665bcda7652SAl Viro error = -ELOOP; 666bcda7652SAl Viro } 667bcda7652SAl Viro } 6681da177e4SLinus Torvalds } 6691da177e4SLinus Torvalds return error; 6701da177e4SLinus Torvalds } 6711da177e4SLinus Torvalds 67231e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 67331e6b01fSNick Piggin { 6740714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6750714a533SAl Viro struct mount *parent; 67631e6b01fSNick Piggin struct dentry *mountpoint; 67731e6b01fSNick Piggin 6780714a533SAl Viro parent = mnt->mnt_parent; 6790714a533SAl Viro if (&parent->mnt == path->mnt) 68031e6b01fSNick Piggin return 0; 681a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 68231e6b01fSNick Piggin path->dentry = mountpoint; 6830714a533SAl Viro path->mnt = &parent->mnt; 68431e6b01fSNick Piggin return 1; 68531e6b01fSNick Piggin } 68631e6b01fSNick Piggin 687bab77ebfSAl Viro int follow_up(struct path *path) 6881da177e4SLinus Torvalds { 6890714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 6900714a533SAl Viro struct mount *parent; 6911da177e4SLinus Torvalds struct dentry *mountpoint; 69299b7db7bSNick Piggin 69399b7db7bSNick Piggin br_read_lock(vfsmount_lock); 6940714a533SAl Viro parent = mnt->mnt_parent; 6950714a533SAl Viro if (&parent->mnt == path->mnt) { 69699b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 6971da177e4SLinus Torvalds return 0; 6981da177e4SLinus Torvalds } 6990714a533SAl Viro mntget(&parent->mnt); 700a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 70199b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 702bab77ebfSAl Viro dput(path->dentry); 703bab77ebfSAl Viro path->dentry = mountpoint; 704bab77ebfSAl Viro mntput(path->mnt); 7050714a533SAl Viro path->mnt = &parent->mnt; 7061da177e4SLinus Torvalds return 1; 7071da177e4SLinus Torvalds } 7081da177e4SLinus Torvalds 709b5c84bf6SNick Piggin /* 7109875cf80SDavid Howells * Perform an automount 7119875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7129875cf80SDavid Howells * were called with. 7131da177e4SLinus Torvalds */ 7149875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7159875cf80SDavid Howells bool *need_mntput) 71631e6b01fSNick Piggin { 7179875cf80SDavid Howells struct vfsmount *mnt; 718ea5b778aSDavid Howells int err; 7199875cf80SDavid Howells 7209875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7219875cf80SDavid Howells return -EREMOTE; 7229875cf80SDavid Howells 7230ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 7240ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 7250ec26fd0SMiklos Szeredi * the name. 7260ec26fd0SMiklos Szeredi * 7270ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 7285a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 7290ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 7300ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 7310ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 7320ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 7335a30d8a2SDavid Howells */ 7345a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 735d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 7365a30d8a2SDavid Howells path->dentry->d_inode) 7379875cf80SDavid Howells return -EISDIR; 7380ec26fd0SMiklos Szeredi 7399875cf80SDavid Howells current->total_link_count++; 7409875cf80SDavid Howells if (current->total_link_count >= 40) 7419875cf80SDavid Howells return -ELOOP; 7429875cf80SDavid Howells 7439875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7449875cf80SDavid Howells if (IS_ERR(mnt)) { 7459875cf80SDavid Howells /* 7469875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7479875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7489875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7499875cf80SDavid Howells * 7509875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7519875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7529875cf80SDavid Howells * the path is inaccessible and we should say so. 7539875cf80SDavid Howells */ 75449084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 7559875cf80SDavid Howells return -EREMOTE; 7569875cf80SDavid Howells return PTR_ERR(mnt); 75731e6b01fSNick Piggin } 758ea5b778aSDavid Howells 7599875cf80SDavid Howells if (!mnt) /* mount collision */ 7609875cf80SDavid Howells return 0; 7619875cf80SDavid Howells 7628aef1884SAl Viro if (!*need_mntput) { 7638aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7648aef1884SAl Viro mntget(path->mnt); 7658aef1884SAl Viro *need_mntput = true; 7668aef1884SAl Viro } 76719a167afSAl Viro err = finish_automount(mnt, path); 768ea5b778aSDavid Howells 769ea5b778aSDavid Howells switch (err) { 770ea5b778aSDavid Howells case -EBUSY: 771ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 77219a167afSAl Viro return 0; 773ea5b778aSDavid Howells case 0: 7748aef1884SAl Viro path_put(path); 7759875cf80SDavid Howells path->mnt = mnt; 7769875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7779875cf80SDavid Howells return 0; 77819a167afSAl Viro default: 77919a167afSAl Viro return err; 7809875cf80SDavid Howells } 78119a167afSAl Viro 782ea5b778aSDavid Howells } 7839875cf80SDavid Howells 7849875cf80SDavid Howells /* 7859875cf80SDavid Howells * Handle a dentry that is managed in some way. 786cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7879875cf80SDavid Howells * - Flagged as mountpoint 7889875cf80SDavid Howells * - Flagged as automount point 7899875cf80SDavid Howells * 7909875cf80SDavid Howells * This may only be called in refwalk mode. 7919875cf80SDavid Howells * 7929875cf80SDavid Howells * Serialization is taken care of in namespace.c 7939875cf80SDavid Howells */ 7949875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7959875cf80SDavid Howells { 7968aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 7979875cf80SDavid Howells unsigned managed; 7989875cf80SDavid Howells bool need_mntput = false; 7998aef1884SAl Viro int ret = 0; 8009875cf80SDavid Howells 8019875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8029875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8039875cf80SDavid Howells * the components of that value change under us */ 8049875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8059875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8069875cf80SDavid Howells unlikely(managed != 0)) { 807cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 808cc53ce53SDavid Howells * being held. */ 809cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 810cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 811cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8121aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 813cc53ce53SDavid Howells if (ret < 0) 8148aef1884SAl Viro break; 815cc53ce53SDavid Howells } 816cc53ce53SDavid Howells 8179875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8189875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8199875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8209875cf80SDavid Howells if (mounted) { 8219875cf80SDavid Howells dput(path->dentry); 8229875cf80SDavid Howells if (need_mntput) 823463ffb2eSAl Viro mntput(path->mnt); 824463ffb2eSAl Viro path->mnt = mounted; 825463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8269875cf80SDavid Howells need_mntput = true; 8279875cf80SDavid Howells continue; 828463ffb2eSAl Viro } 829463ffb2eSAl Viro 8309875cf80SDavid Howells /* Something is mounted on this dentry in another 8319875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8329875cf80SDavid Howells * namespace got unmounted before we managed to get the 8339875cf80SDavid Howells * vfsmount_lock */ 8341da177e4SLinus Torvalds } 8359875cf80SDavid Howells 8369875cf80SDavid Howells /* Handle an automount point */ 8379875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8389875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8399875cf80SDavid Howells if (ret < 0) 8408aef1884SAl Viro break; 8419875cf80SDavid Howells continue; 8429875cf80SDavid Howells } 8439875cf80SDavid Howells 8449875cf80SDavid Howells /* We didn't change the current path point */ 8459875cf80SDavid Howells break; 8469875cf80SDavid Howells } 8478aef1884SAl Viro 8488aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8498aef1884SAl Viro mntput(path->mnt); 8508aef1884SAl Viro if (ret == -EISDIR) 8518aef1884SAl Viro ret = 0; 852a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 8531da177e4SLinus Torvalds } 8541da177e4SLinus Torvalds 855cc53ce53SDavid Howells int follow_down_one(struct path *path) 8561da177e4SLinus Torvalds { 8571da177e4SLinus Torvalds struct vfsmount *mounted; 8581da177e4SLinus Torvalds 8591c755af4SAl Viro mounted = lookup_mnt(path); 8601da177e4SLinus Torvalds if (mounted) { 8619393bd07SAl Viro dput(path->dentry); 8629393bd07SAl Viro mntput(path->mnt); 8639393bd07SAl Viro path->mnt = mounted; 8649393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8651da177e4SLinus Torvalds return 1; 8661da177e4SLinus Torvalds } 8671da177e4SLinus Torvalds return 0; 8681da177e4SLinus Torvalds } 8691da177e4SLinus Torvalds 87062a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 87162a7375eSIan Kent { 87262a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 87362a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 87462a7375eSIan Kent } 87562a7375eSIan Kent 8769875cf80SDavid Howells /* 877287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 878287548e4SAl Viro * we meet a managed dentry that would need blocking. 8799875cf80SDavid Howells */ 8809875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 881287548e4SAl Viro struct inode **inode) 8829875cf80SDavid Howells { 88362a7375eSIan Kent for (;;) { 884c7105365SAl Viro struct mount *mounted; 88562a7375eSIan Kent /* 88662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 88762a7375eSIan Kent * that wants to block transit. 88862a7375eSIan Kent */ 889287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 890ab90911fSDavid Howells return false; 89162a7375eSIan Kent 89262a7375eSIan Kent if (!d_mountpoint(path->dentry)) 89362a7375eSIan Kent break; 89462a7375eSIan Kent 8959875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 8969875cf80SDavid Howells if (!mounted) 8979875cf80SDavid Howells break; 898c7105365SAl Viro path->mnt = &mounted->mnt; 899c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 900a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 9019875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 90259430262SLinus Torvalds /* 90359430262SLinus Torvalds * Update the inode too. We don't need to re-check the 90459430262SLinus Torvalds * dentry sequence number here after this d_inode read, 90559430262SLinus Torvalds * because a mount-point is always pinned. 90659430262SLinus Torvalds */ 90759430262SLinus Torvalds *inode = path->dentry->d_inode; 9089875cf80SDavid Howells } 9099875cf80SDavid Howells return true; 9109875cf80SDavid Howells } 9119875cf80SDavid Howells 912dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 913287548e4SAl Viro { 914dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 915c7105365SAl Viro struct mount *mounted; 916dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 917287548e4SAl Viro if (!mounted) 918287548e4SAl Viro break; 919c7105365SAl Viro nd->path.mnt = &mounted->mnt; 920c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 921dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 922287548e4SAl Viro } 923287548e4SAl Viro } 924287548e4SAl Viro 92531e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 92631e6b01fSNick Piggin { 92731e6b01fSNick Piggin set_root_rcu(nd); 92831e6b01fSNick Piggin 92931e6b01fSNick Piggin while (1) { 93031e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 93131e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 93231e6b01fSNick Piggin break; 93331e6b01fSNick Piggin } 93431e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 93531e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 93631e6b01fSNick Piggin struct dentry *parent = old->d_parent; 93731e6b01fSNick Piggin unsigned seq; 93831e6b01fSNick Piggin 93931e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 94031e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 941ef7562d5SAl Viro goto failed; 94231e6b01fSNick Piggin nd->path.dentry = parent; 94331e6b01fSNick Piggin nd->seq = seq; 94431e6b01fSNick Piggin break; 94531e6b01fSNick Piggin } 94631e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 94731e6b01fSNick Piggin break; 94831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 94931e6b01fSNick Piggin } 950dea39376SAl Viro follow_mount_rcu(nd); 951dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 95231e6b01fSNick Piggin return 0; 953ef7562d5SAl Viro 954ef7562d5SAl Viro failed: 955ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 9565b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 957ef7562d5SAl Viro nd->root.mnt = NULL; 958ef7562d5SAl Viro rcu_read_unlock(); 959ef7562d5SAl Viro br_read_unlock(vfsmount_lock); 960ef7562d5SAl Viro return -ECHILD; 96131e6b01fSNick Piggin } 96231e6b01fSNick Piggin 9639875cf80SDavid Howells /* 964cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 965cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 966cc53ce53SDavid Howells * caller is permitted to proceed or not. 967cc53ce53SDavid Howells */ 9687cc90cc3SAl Viro int follow_down(struct path *path) 969cc53ce53SDavid Howells { 970cc53ce53SDavid Howells unsigned managed; 971cc53ce53SDavid Howells int ret; 972cc53ce53SDavid Howells 973cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 974cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 975cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 976cc53ce53SDavid Howells * being held. 977cc53ce53SDavid Howells * 978cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 979cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 980cc53ce53SDavid Howells * other than its daemon the right to mount on its 981cc53ce53SDavid Howells * superstructure. 982cc53ce53SDavid Howells * 983cc53ce53SDavid Howells * The filesystem may sleep at this point. 984cc53ce53SDavid Howells */ 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); 988ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 9891aed3e42SAl Viro path->dentry, false); 990cc53ce53SDavid Howells if (ret < 0) 991cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 992cc53ce53SDavid Howells } 993cc53ce53SDavid Howells 994cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 995cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 996cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 997cc53ce53SDavid Howells if (!mounted) 998cc53ce53SDavid Howells break; 999cc53ce53SDavid Howells dput(path->dentry); 1000cc53ce53SDavid Howells mntput(path->mnt); 1001cc53ce53SDavid Howells path->mnt = mounted; 1002cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1003cc53ce53SDavid Howells continue; 1004cc53ce53SDavid Howells } 1005cc53ce53SDavid Howells 1006cc53ce53SDavid Howells /* Don't handle automount points here */ 1007cc53ce53SDavid Howells break; 1008cc53ce53SDavid Howells } 1009cc53ce53SDavid Howells return 0; 1010cc53ce53SDavid Howells } 1011cc53ce53SDavid Howells 1012cc53ce53SDavid Howells /* 10139875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 10149875cf80SDavid Howells */ 10159875cf80SDavid Howells static void follow_mount(struct path *path) 10169875cf80SDavid Howells { 10179875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 10189875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10199875cf80SDavid Howells if (!mounted) 10209875cf80SDavid Howells break; 10219875cf80SDavid Howells dput(path->dentry); 10229875cf80SDavid Howells mntput(path->mnt); 10239875cf80SDavid Howells path->mnt = mounted; 10249875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 10259875cf80SDavid Howells } 10269875cf80SDavid Howells } 10279875cf80SDavid Howells 102831e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 10291da177e4SLinus Torvalds { 10302a737871SAl Viro set_root(nd); 1031e518ddb7SAndreas Mohr 10321da177e4SLinus Torvalds while(1) { 10334ac91378SJan Blunck struct dentry *old = nd->path.dentry; 10341da177e4SLinus Torvalds 10352a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 10362a737871SAl Viro nd->path.mnt == nd->root.mnt) { 10371da177e4SLinus Torvalds break; 10381da177e4SLinus Torvalds } 10394ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 10403088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 10413088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 10421da177e4SLinus Torvalds dput(old); 10431da177e4SLinus Torvalds break; 10441da177e4SLinus Torvalds } 10453088dd70SAl Viro if (!follow_up(&nd->path)) 10461da177e4SLinus Torvalds break; 10471da177e4SLinus Torvalds } 104879ed0226SAl Viro follow_mount(&nd->path); 104931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 10501da177e4SLinus Torvalds } 10511da177e4SLinus Torvalds 10521da177e4SLinus Torvalds /* 1053bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1054bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1055bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1056bad61189SMiklos Szeredi * 1057bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1058baa03890SNick Piggin */ 1059bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1060bad61189SMiklos Szeredi struct nameidata *nd, bool *need_lookup) 1061baa03890SNick Piggin { 1062baa03890SNick Piggin struct dentry *dentry; 1063bad61189SMiklos Szeredi int error; 1064baa03890SNick Piggin 1065bad61189SMiklos Szeredi *need_lookup = false; 1066bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1067bad61189SMiklos Szeredi if (dentry) { 1068bad61189SMiklos Szeredi if (d_need_lookup(dentry)) { 1069bad61189SMiklos Szeredi *need_lookup = true; 1070bad61189SMiklos Szeredi } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1071bad61189SMiklos Szeredi error = d_revalidate(dentry, nd); 1072bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1073bad61189SMiklos Szeredi if (error < 0) { 1074bad61189SMiklos Szeredi dput(dentry); 1075bad61189SMiklos Szeredi return ERR_PTR(error); 1076bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1077bad61189SMiklos Szeredi dput(dentry); 1078bad61189SMiklos Szeredi dentry = NULL; 1079bad61189SMiklos Szeredi } 1080bad61189SMiklos Szeredi } 1081bad61189SMiklos Szeredi } 1082bad61189SMiklos Szeredi } 1083baa03890SNick Piggin 1084bad61189SMiklos Szeredi if (!dentry) { 1085bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1086baa03890SNick Piggin if (unlikely(!dentry)) 1087baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1088baa03890SNick Piggin 1089bad61189SMiklos Szeredi *need_lookup = true; 1090baa03890SNick Piggin } 1091baa03890SNick Piggin return dentry; 1092baa03890SNick Piggin } 1093baa03890SNick Piggin 1094baa03890SNick Piggin /* 1095bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1096bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1097bad61189SMiklos Szeredi * 1098bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 109944396f4bSJosef Bacik */ 1100bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 110144396f4bSJosef Bacik struct nameidata *nd) 110244396f4bSJosef Bacik { 110344396f4bSJosef Bacik struct dentry *old; 110444396f4bSJosef Bacik 110544396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1106bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1107e188dc02SMiklos Szeredi dput(dentry); 110844396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1109e188dc02SMiklos Szeredi } 111044396f4bSJosef Bacik 1111bad61189SMiklos Szeredi old = dir->i_op->lookup(dir, dentry, nd); 111244396f4bSJosef Bacik if (unlikely(old)) { 111344396f4bSJosef Bacik dput(dentry); 111444396f4bSJosef Bacik dentry = old; 111544396f4bSJosef Bacik } 111644396f4bSJosef Bacik return dentry; 111744396f4bSJosef Bacik } 111844396f4bSJosef Bacik 1119a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 1120a3255546SAl Viro struct dentry *base, struct nameidata *nd) 1121a3255546SAl Viro { 1122bad61189SMiklos Szeredi bool need_lookup; 1123a3255546SAl Viro struct dentry *dentry; 1124a3255546SAl Viro 1125bad61189SMiklos Szeredi dentry = lookup_dcache(name, base, nd, &need_lookup); 1126bad61189SMiklos Szeredi if (!need_lookup) 1127a3255546SAl Viro return dentry; 1128bad61189SMiklos Szeredi 1129bad61189SMiklos Szeredi return lookup_real(base->d_inode, dentry, nd); 1130a3255546SAl Viro } 1131a3255546SAl Viro 113244396f4bSJosef Bacik /* 11331da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11341da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11351da177e4SLinus Torvalds * It _is_ time-critical. 11361da177e4SLinus Torvalds */ 11371da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 113831e6b01fSNick Piggin struct path *path, struct inode **inode) 11391da177e4SLinus Torvalds { 11404ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 114131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11425a18fff2SAl Viro int need_reval = 1; 11435a18fff2SAl Viro int status = 1; 11449875cf80SDavid Howells int err; 11459875cf80SDavid Howells 11463cac260aSAl Viro /* 1147b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1148b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1149b04f784eSNick Piggin * do the non-racy lookup, below. 1150b04f784eSNick Piggin */ 115131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 115231e6b01fSNick Piggin unsigned seq; 115331e6b01fSNick Piggin *inode = nd->inode; 115431e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11555a18fff2SAl Viro if (!dentry) 11565a18fff2SAl Viro goto unlazy; 11575a18fff2SAl Viro 115831e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 115931e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 116031e6b01fSNick Piggin return -ECHILD; 116131e6b01fSNick Piggin nd->seq = seq; 11625a18fff2SAl Viro 1163fa4ee159SMiklos Szeredi if (unlikely(d_need_lookup(dentry))) 1164fa4ee159SMiklos Szeredi goto unlazy; 116524643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11665a18fff2SAl Viro status = d_revalidate(dentry, nd); 11675a18fff2SAl Viro if (unlikely(status <= 0)) { 11685a18fff2SAl Viro if (status != -ECHILD) 11695a18fff2SAl Viro need_reval = 0; 11705a18fff2SAl Viro goto unlazy; 11715a18fff2SAl Viro } 117224643087SAl Viro } 117331e6b01fSNick Piggin path->mnt = mnt; 117431e6b01fSNick Piggin path->dentry = dentry; 1175d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1176d6e9bd25SAl Viro goto unlazy; 1177d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1178d6e9bd25SAl Viro goto unlazy; 11799875cf80SDavid Howells return 0; 11805a18fff2SAl Viro unlazy: 118119660af7SAl Viro if (unlazy_walk(nd, dentry)) 11825a18fff2SAl Viro return -ECHILD; 11835a18fff2SAl Viro } else { 118431e6b01fSNick Piggin dentry = __d_lookup(parent, name); 118524643087SAl Viro } 11865a18fff2SAl Viro 118781e6f520SAl Viro if (unlikely(!dentry)) 118881e6f520SAl Viro goto need_lookup; 11895a18fff2SAl Viro 119081e6f520SAl Viro if (unlikely(d_need_lookup(dentry))) { 119181e6f520SAl Viro dput(dentry); 119281e6f520SAl Viro goto need_lookup; 11935a18fff2SAl Viro } 119481e6f520SAl Viro 11955a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 11965a18fff2SAl Viro status = d_revalidate(dentry, nd); 11975a18fff2SAl Viro if (unlikely(status <= 0)) { 11985a18fff2SAl Viro if (status < 0) { 11995a18fff2SAl Viro dput(dentry); 12005a18fff2SAl Viro return status; 12015a18fff2SAl Viro } 12025a18fff2SAl Viro if (!d_invalidate(dentry)) { 12035a18fff2SAl Viro dput(dentry); 120481e6f520SAl Viro goto need_lookup; 12055a18fff2SAl Viro } 12065a18fff2SAl Viro } 12073f6c7c71SAl Viro done: 12081da177e4SLinus Torvalds path->mnt = mnt; 12091da177e4SLinus Torvalds path->dentry = dentry; 12109875cf80SDavid Howells err = follow_managed(path, nd->flags); 121189312214SIan Kent if (unlikely(err < 0)) { 121289312214SIan Kent path_put_conditional(path, nd); 12139875cf80SDavid Howells return err; 121489312214SIan Kent } 1215a3fbbde7SAl Viro if (err) 1216a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 121731e6b01fSNick Piggin *inode = path->dentry->d_inode; 12181da177e4SLinus Torvalds return 0; 121981e6f520SAl Viro 122081e6f520SAl Viro need_lookup: 122181e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 122281e6f520SAl Viro 122381e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 122481e6f520SAl Viro dentry = __lookup_hash(name, parent, nd); 122581e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 122681e6f520SAl Viro if (IS_ERR(dentry)) 122781e6f520SAl Viro return PTR_ERR(dentry); 122881e6f520SAl Viro goto done; 12291da177e4SLinus Torvalds } 12301da177e4SLinus Torvalds 123152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 123252094c8aSAl Viro { 123352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 12344ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 123552094c8aSAl Viro if (err != -ECHILD) 123652094c8aSAl Viro return err; 123719660af7SAl Viro if (unlazy_walk(nd, NULL)) 123852094c8aSAl Viro return -ECHILD; 123952094c8aSAl Viro } 12404ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 124152094c8aSAl Viro } 124252094c8aSAl Viro 12439856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12449856fa1bSAl Viro { 12459856fa1bSAl Viro if (type == LAST_DOTDOT) { 12469856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12479856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12489856fa1bSAl Viro return -ECHILD; 12499856fa1bSAl Viro } else 12509856fa1bSAl Viro follow_dotdot(nd); 12519856fa1bSAl Viro } 12529856fa1bSAl Viro return 0; 12539856fa1bSAl Viro } 12549856fa1bSAl Viro 1255951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1256951361f9SAl Viro { 1257951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1258951361f9SAl Viro path_put(&nd->path); 1259951361f9SAl Viro } else { 1260951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12615b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1262951361f9SAl Viro nd->root.mnt = NULL; 1263951361f9SAl Viro rcu_read_unlock(); 1264951361f9SAl Viro br_read_unlock(vfsmount_lock); 1265951361f9SAl Viro } 1266951361f9SAl Viro } 1267951361f9SAl Viro 12683ddcd056SLinus Torvalds /* 12693ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 12703ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 12713ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 12723ddcd056SLinus Torvalds * for the common case. 12733ddcd056SLinus Torvalds */ 12747813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 12753ddcd056SLinus Torvalds { 12763ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 12773ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 12783ddcd056SLinus Torvalds return follow; 12793ddcd056SLinus Torvalds 12803ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 12813ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 12823ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 12833ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 12843ddcd056SLinus Torvalds } 12853ddcd056SLinus Torvalds return 0; 12863ddcd056SLinus Torvalds } 12873ddcd056SLinus Torvalds 1288ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1289ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1290ce57dfc1SAl Viro { 1291ce57dfc1SAl Viro struct inode *inode; 1292ce57dfc1SAl Viro int err; 1293ce57dfc1SAl Viro /* 1294ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1295ce57dfc1SAl Viro * to be able to know about the current root directory and 1296ce57dfc1SAl Viro * parent relationships. 1297ce57dfc1SAl Viro */ 1298ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1299ce57dfc1SAl Viro return handle_dots(nd, type); 1300ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1301ce57dfc1SAl Viro if (unlikely(err)) { 1302ce57dfc1SAl Viro terminate_walk(nd); 1303ce57dfc1SAl Viro return err; 1304ce57dfc1SAl Viro } 1305ce57dfc1SAl Viro if (!inode) { 1306ce57dfc1SAl Viro path_to_nameidata(path, nd); 1307ce57dfc1SAl Viro terminate_walk(nd); 1308ce57dfc1SAl Viro return -ENOENT; 1309ce57dfc1SAl Viro } 13107813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 131119660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 131219660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 131319660af7SAl Viro terminate_walk(nd); 1314ce57dfc1SAl Viro return -ECHILD; 131519660af7SAl Viro } 131619660af7SAl Viro } 1317ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1318ce57dfc1SAl Viro return 1; 1319ce57dfc1SAl Viro } 1320ce57dfc1SAl Viro path_to_nameidata(path, nd); 1321ce57dfc1SAl Viro nd->inode = inode; 1322ce57dfc1SAl Viro return 0; 1323ce57dfc1SAl Viro } 1324ce57dfc1SAl Viro 13251da177e4SLinus Torvalds /* 1326b356379aSAl Viro * This limits recursive symlink follows to 8, while 1327b356379aSAl Viro * limiting consecutive symlinks to 40. 1328b356379aSAl Viro * 1329b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1330b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1331b356379aSAl Viro */ 1332b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1333b356379aSAl Viro { 1334b356379aSAl Viro int res; 1335b356379aSAl Viro 1336b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1337b356379aSAl Viro path_put_conditional(path, nd); 1338b356379aSAl Viro path_put(&nd->path); 1339b356379aSAl Viro return -ELOOP; 1340b356379aSAl Viro } 13411a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1342b356379aSAl Viro 1343b356379aSAl Viro nd->depth++; 1344b356379aSAl Viro current->link_count++; 1345b356379aSAl Viro 1346b356379aSAl Viro do { 1347b356379aSAl Viro struct path link = *path; 1348b356379aSAl Viro void *cookie; 1349574197e0SAl Viro 1350574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1351b356379aSAl Viro if (!res) 1352b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1353b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1354574197e0SAl Viro put_link(nd, &link, cookie); 1355b356379aSAl Viro } while (res > 0); 1356b356379aSAl Viro 1357b356379aSAl Viro current->link_count--; 1358b356379aSAl Viro nd->depth--; 1359b356379aSAl Viro return res; 1360b356379aSAl Viro } 1361b356379aSAl Viro 1362b356379aSAl Viro /* 13633ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 13643ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 13653ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 13663ddcd056SLinus Torvalds * do lookup on this inode". 13673ddcd056SLinus Torvalds */ 13683ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 13693ddcd056SLinus Torvalds { 13703ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 13713ddcd056SLinus Torvalds return 1; 13723ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 13733ddcd056SLinus Torvalds return 0; 13743ddcd056SLinus Torvalds 13753ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 13763ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13773ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 13783ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13793ddcd056SLinus Torvalds return 1; 13803ddcd056SLinus Torvalds } 13813ddcd056SLinus Torvalds 1382bfcfaa77SLinus Torvalds /* 1383bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1384bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1385bfcfaa77SLinus Torvalds * 1386bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1387bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1388bfcfaa77SLinus Torvalds * fast. 1389bfcfaa77SLinus Torvalds * 1390bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1391bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1392bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1393bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1394bfcfaa77SLinus Torvalds * 1395bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1396bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1397bfcfaa77SLinus Torvalds * crossing operation. 1398bfcfaa77SLinus Torvalds * 1399bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1400bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1401bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1402bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1403bfcfaa77SLinus Torvalds */ 1404bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1405bfcfaa77SLinus Torvalds 1406bfcfaa77SLinus Torvalds #ifdef CONFIG_64BIT 1407bfcfaa77SLinus Torvalds 1408bfcfaa77SLinus Torvalds /* 1409bfcfaa77SLinus Torvalds * Jan Achrenius on G+: microoptimized version of 1410bfcfaa77SLinus Torvalds * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56" 1411bfcfaa77SLinus Torvalds * that works for the bytemasks without having to 1412bfcfaa77SLinus Torvalds * mask them first. 1413bfcfaa77SLinus Torvalds */ 1414bfcfaa77SLinus Torvalds static inline long count_masked_bytes(unsigned long mask) 1415bfcfaa77SLinus Torvalds { 1416f7493e5dSLinus Torvalds return mask*0x0001020304050608ul >> 56; 1417bfcfaa77SLinus Torvalds } 1418bfcfaa77SLinus Torvalds 1419bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1420bfcfaa77SLinus Torvalds { 1421bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1422bfcfaa77SLinus Torvalds return hash; 1423bfcfaa77SLinus Torvalds } 1424bfcfaa77SLinus Torvalds 1425bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1426bfcfaa77SLinus Torvalds 1427bfcfaa77SLinus Torvalds /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */ 1428bfcfaa77SLinus Torvalds static inline long count_masked_bytes(long mask) 1429bfcfaa77SLinus Torvalds { 1430bfcfaa77SLinus Torvalds /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */ 1431bfcfaa77SLinus Torvalds long a = (0x0ff0001+mask) >> 23; 1432bfcfaa77SLinus Torvalds /* Fix the 1 for 00 case */ 1433bfcfaa77SLinus Torvalds return a & mask; 1434bfcfaa77SLinus Torvalds } 1435bfcfaa77SLinus Torvalds 1436bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1437bfcfaa77SLinus Torvalds 1438bfcfaa77SLinus Torvalds #endif 1439bfcfaa77SLinus Torvalds 1440bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1441bfcfaa77SLinus Torvalds { 1442bfcfaa77SLinus Torvalds unsigned long a, mask; 1443bfcfaa77SLinus Torvalds unsigned long hash = 0; 1444bfcfaa77SLinus Torvalds 1445bfcfaa77SLinus Torvalds for (;;) { 1446bfcfaa77SLinus Torvalds a = *(unsigned long *)name; 1447bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1448bfcfaa77SLinus Torvalds break; 1449bfcfaa77SLinus Torvalds hash += a; 1450f132c5beSAl Viro hash *= 9; 1451bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1452bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1453bfcfaa77SLinus Torvalds if (!len) 1454bfcfaa77SLinus Torvalds goto done; 1455bfcfaa77SLinus Torvalds } 1456bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1457bfcfaa77SLinus Torvalds hash += mask & a; 1458bfcfaa77SLinus Torvalds done: 1459bfcfaa77SLinus Torvalds return fold_hash(hash); 1460bfcfaa77SLinus Torvalds } 1461bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1462bfcfaa77SLinus Torvalds 1463989412bbSLinus Torvalds #define REPEAT_BYTE(x) ((~0ul / 0xff) * (x)) 1464989412bbSLinus Torvalds #define ONEBYTES REPEAT_BYTE(0x01) 1465989412bbSLinus Torvalds #define SLASHBYTES REPEAT_BYTE('/') 1466989412bbSLinus Torvalds #define HIGHBITS REPEAT_BYTE(0x80) 1467bfcfaa77SLinus Torvalds 1468bfcfaa77SLinus Torvalds /* Return the high bit set in the first byte that is a zero */ 1469bfcfaa77SLinus Torvalds static inline unsigned long has_zero(unsigned long a) 1470bfcfaa77SLinus Torvalds { 1471bfcfaa77SLinus Torvalds return ((a - ONEBYTES) & ~a) & HIGHBITS; 1472bfcfaa77SLinus Torvalds } 1473bfcfaa77SLinus Torvalds 1474bfcfaa77SLinus Torvalds /* 1475bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1476bfcfaa77SLinus Torvalds * return the length of the component; 1477bfcfaa77SLinus Torvalds */ 1478bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1479bfcfaa77SLinus Torvalds { 1480bfcfaa77SLinus Torvalds unsigned long a, mask, hash, len; 1481bfcfaa77SLinus Torvalds 1482bfcfaa77SLinus Torvalds hash = a = 0; 1483bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1484bfcfaa77SLinus Torvalds do { 1485bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1486bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1487bfcfaa77SLinus Torvalds a = *(unsigned long *)(name+len); 1488bfcfaa77SLinus Torvalds /* Do we have any NUL or '/' bytes in this word? */ 1489bfcfaa77SLinus Torvalds mask = has_zero(a) | has_zero(a ^ SLASHBYTES); 1490bfcfaa77SLinus Torvalds } while (!mask); 1491bfcfaa77SLinus Torvalds 1492bfcfaa77SLinus Torvalds /* The mask *below* the first high bit set */ 1493bfcfaa77SLinus Torvalds mask = (mask - 1) & ~mask; 1494bfcfaa77SLinus Torvalds mask >>= 7; 1495bfcfaa77SLinus Torvalds hash += a & mask; 1496bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1497bfcfaa77SLinus Torvalds 1498bfcfaa77SLinus Torvalds return len + count_masked_bytes(mask); 1499bfcfaa77SLinus Torvalds } 1500bfcfaa77SLinus Torvalds 1501bfcfaa77SLinus Torvalds #else 1502bfcfaa77SLinus Torvalds 15030145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 15040145acc2SLinus Torvalds { 15050145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 15060145acc2SLinus Torvalds while (len--) 15070145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 15080145acc2SLinus Torvalds return end_name_hash(hash); 15090145acc2SLinus Torvalds } 1510ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 15110145acc2SLinus Torvalds 15123ddcd056SLinus Torvalds /* 1513200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1514200e9ef7SLinus Torvalds * one character. 1515200e9ef7SLinus Torvalds */ 1516200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1517200e9ef7SLinus Torvalds { 1518200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1519200e9ef7SLinus Torvalds unsigned long len = 0, c; 1520200e9ef7SLinus Torvalds 1521200e9ef7SLinus Torvalds c = (unsigned char)*name; 1522200e9ef7SLinus Torvalds do { 1523200e9ef7SLinus Torvalds len++; 1524200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1525200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1526200e9ef7SLinus Torvalds } while (c && c != '/'); 1527200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1528200e9ef7SLinus Torvalds return len; 1529200e9ef7SLinus Torvalds } 1530200e9ef7SLinus Torvalds 1531bfcfaa77SLinus Torvalds #endif 1532bfcfaa77SLinus Torvalds 1533200e9ef7SLinus Torvalds /* 15341da177e4SLinus Torvalds * Name resolution. 1535ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1536ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 15371da177e4SLinus Torvalds * 1538ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1539ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 15401da177e4SLinus Torvalds */ 15416de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 15421da177e4SLinus Torvalds { 15431da177e4SLinus Torvalds struct path next; 15441da177e4SLinus Torvalds int err; 15451da177e4SLinus Torvalds 15461da177e4SLinus Torvalds while (*name=='/') 15471da177e4SLinus Torvalds name++; 15481da177e4SLinus Torvalds if (!*name) 1549086e183aSAl Viro return 0; 15501da177e4SLinus Torvalds 15511da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 15521da177e4SLinus Torvalds for(;;) { 15531da177e4SLinus Torvalds struct qstr this; 1554200e9ef7SLinus Torvalds long len; 1555fe479a58SAl Viro int type; 15561da177e4SLinus Torvalds 155752094c8aSAl Viro err = may_lookup(nd); 15581da177e4SLinus Torvalds if (err) 15591da177e4SLinus Torvalds break; 15601da177e4SLinus Torvalds 1561200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 15621da177e4SLinus Torvalds this.name = name; 1563200e9ef7SLinus Torvalds this.len = len; 15641da177e4SLinus Torvalds 1565fe479a58SAl Viro type = LAST_NORM; 1566200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1567fe479a58SAl Viro case 2: 1568200e9ef7SLinus Torvalds if (name[1] == '.') { 1569fe479a58SAl Viro type = LAST_DOTDOT; 157016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 157116c2cd71SAl Viro } 1572fe479a58SAl Viro break; 1573fe479a58SAl Viro case 1: 1574fe479a58SAl Viro type = LAST_DOT; 1575fe479a58SAl Viro } 15765a202bcdSAl Viro if (likely(type == LAST_NORM)) { 15775a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 157816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 15795a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 15805a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 15815a202bcdSAl Viro &this); 15825a202bcdSAl Viro if (err < 0) 15835a202bcdSAl Viro break; 15845a202bcdSAl Viro } 15855a202bcdSAl Viro } 1586fe479a58SAl Viro 1587200e9ef7SLinus Torvalds if (!name[len]) 15881da177e4SLinus Torvalds goto last_component; 1589200e9ef7SLinus Torvalds /* 1590200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1591200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1592200e9ef7SLinus Torvalds */ 1593200e9ef7SLinus Torvalds do { 1594200e9ef7SLinus Torvalds len++; 1595200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1596200e9ef7SLinus Torvalds if (!name[len]) 1597b356379aSAl Viro goto last_component; 1598200e9ef7SLinus Torvalds name += len; 15991da177e4SLinus Torvalds 1600ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1601ce57dfc1SAl Viro if (err < 0) 1602ce57dfc1SAl Viro return err; 1603fe479a58SAl Viro 1604ce57dfc1SAl Viro if (err) { 1605b356379aSAl Viro err = nested_symlink(&next, nd); 16061da177e4SLinus Torvalds if (err) 1607a7472babSAl Viro return err; 160831e6b01fSNick Piggin } 16093ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 16101da177e4SLinus Torvalds continue; 16113ddcd056SLinus Torvalds err = -ENOTDIR; 16123ddcd056SLinus Torvalds break; 16131da177e4SLinus Torvalds /* here ends the main loop */ 16141da177e4SLinus Torvalds 16151da177e4SLinus Torvalds last_component: 1616ce57dfc1SAl Viro nd->last = this; 1617ce57dfc1SAl Viro nd->last_type = type; 1618ce57dfc1SAl Viro return 0; 1619ce57dfc1SAl Viro } 1620951361f9SAl Viro terminate_walk(nd); 16211da177e4SLinus Torvalds return err; 16221da177e4SLinus Torvalds } 16231da177e4SLinus Torvalds 162470e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 162570e9b357SAl Viro struct nameidata *nd, struct file **fp) 162631e6b01fSNick Piggin { 162731e6b01fSNick Piggin int retval = 0; 162831e6b01fSNick Piggin int fput_needed; 162931e6b01fSNick Piggin struct file *file; 163031e6b01fSNick Piggin 163131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 163216c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 163331e6b01fSNick Piggin nd->depth = 0; 16345b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 16355b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 163673d049a4SAl Viro if (*name) { 16375b6ca027SAl Viro if (!inode->i_op->lookup) 16385b6ca027SAl Viro return -ENOTDIR; 16395b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 16405b6ca027SAl Viro if (retval) 16415b6ca027SAl Viro return retval; 164273d049a4SAl Viro } 16435b6ca027SAl Viro nd->path = nd->root; 16445b6ca027SAl Viro nd->inode = inode; 16455b6ca027SAl Viro if (flags & LOOKUP_RCU) { 16465b6ca027SAl Viro br_read_lock(vfsmount_lock); 16475b6ca027SAl Viro rcu_read_lock(); 16485b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 16495b6ca027SAl Viro } else { 16505b6ca027SAl Viro path_get(&nd->path); 16515b6ca027SAl Viro } 16525b6ca027SAl Viro return 0; 16535b6ca027SAl Viro } 16545b6ca027SAl Viro 165531e6b01fSNick Piggin nd->root.mnt = NULL; 165631e6b01fSNick Piggin 165731e6b01fSNick Piggin if (*name=='/') { 1658e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 165931e6b01fSNick Piggin br_read_lock(vfsmount_lock); 166031e6b01fSNick Piggin rcu_read_lock(); 1661e41f7d4eSAl Viro set_root_rcu(nd); 1662e41f7d4eSAl Viro } else { 1663e41f7d4eSAl Viro set_root(nd); 1664e41f7d4eSAl Viro path_get(&nd->root); 1665e41f7d4eSAl Viro } 166631e6b01fSNick Piggin nd->path = nd->root; 166731e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1668e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 166931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1670c28cc364SNick Piggin unsigned seq; 167131e6b01fSNick Piggin 167231e6b01fSNick Piggin br_read_lock(vfsmount_lock); 167331e6b01fSNick Piggin rcu_read_lock(); 167431e6b01fSNick Piggin 1675c28cc364SNick Piggin do { 1676c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 167731e6b01fSNick Piggin nd->path = fs->pwd; 1678c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1679c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1680e41f7d4eSAl Viro } else { 1681e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1682e41f7d4eSAl Viro } 168331e6b01fSNick Piggin } else { 168431e6b01fSNick Piggin struct dentry *dentry; 168531e6b01fSNick Piggin 16861abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 168731e6b01fSNick Piggin retval = -EBADF; 168831e6b01fSNick Piggin if (!file) 168931e6b01fSNick Piggin goto out_fail; 169031e6b01fSNick Piggin 169131e6b01fSNick Piggin dentry = file->f_path.dentry; 169231e6b01fSNick Piggin 1693f52e0c11SAl Viro if (*name) { 169431e6b01fSNick Piggin retval = -ENOTDIR; 169531e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 169631e6b01fSNick Piggin goto fput_fail; 169731e6b01fSNick Piggin 16984ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 169931e6b01fSNick Piggin if (retval) 170031e6b01fSNick Piggin goto fput_fail; 1701f52e0c11SAl Viro } 170231e6b01fSNick Piggin 170331e6b01fSNick Piggin nd->path = file->f_path; 1704e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 170531e6b01fSNick Piggin if (fput_needed) 170670e9b357SAl Viro *fp = file; 1707c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 170831e6b01fSNick Piggin br_read_lock(vfsmount_lock); 170931e6b01fSNick Piggin rcu_read_lock(); 17105590ff0dSUlrich Drepper } else { 17115dd784d0SJan Blunck path_get(&file->f_path); 17125590ff0dSUlrich Drepper fput_light(file, fput_needed); 17131da177e4SLinus Torvalds } 1714e41f7d4eSAl Viro } 1715e41f7d4eSAl Viro 171631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 17179b4a9b14SAl Viro return 0; 17182dfdd266SJosef 'Jeff' Sipek 17199b4a9b14SAl Viro fput_fail: 17209b4a9b14SAl Viro fput_light(file, fput_needed); 17219b4a9b14SAl Viro out_fail: 17229b4a9b14SAl Viro return retval; 17239b4a9b14SAl Viro } 17249b4a9b14SAl Viro 1725bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1726bd92d7feSAl Viro { 1727bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1728bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1729bd92d7feSAl Viro 1730bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1731bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1732bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1733bd92d7feSAl Viro } 1734bd92d7feSAl Viro 17359b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1736ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 17379b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 17389b4a9b14SAl Viro { 173970e9b357SAl Viro struct file *base = NULL; 1740bd92d7feSAl Viro struct path path; 1741bd92d7feSAl Viro int err; 174231e6b01fSNick Piggin 174331e6b01fSNick Piggin /* 174431e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 174531e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 174631e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 174731e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 174831e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 174931e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 175031e6b01fSNick Piggin * analogue, foo_rcu(). 175131e6b01fSNick Piggin * 175231e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 175331e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 175431e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 175531e6b01fSNick Piggin * be able to complete). 175631e6b01fSNick Piggin */ 1757bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1758ee0827cdSAl Viro 1759bd92d7feSAl Viro if (unlikely(err)) 1760bd92d7feSAl Viro return err; 1761ee0827cdSAl Viro 1762ee0827cdSAl Viro current->total_link_count = 0; 1763bd92d7feSAl Viro err = link_path_walk(name, nd); 1764bd92d7feSAl Viro 1765bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1766bd92d7feSAl Viro err = lookup_last(nd, &path); 1767bd92d7feSAl Viro while (err > 0) { 1768bd92d7feSAl Viro void *cookie; 1769bd92d7feSAl Viro struct path link = path; 1770bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1771574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1772bd92d7feSAl Viro if (!err) 1773bd92d7feSAl Viro err = lookup_last(nd, &path); 1774574197e0SAl Viro put_link(nd, &link, cookie); 1775bd92d7feSAl Viro } 1776bd92d7feSAl Viro } 1777ee0827cdSAl Viro 17789f1fafeeSAl Viro if (!err) 17799f1fafeeSAl Viro err = complete_walk(nd); 1780bd92d7feSAl Viro 1781bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1782bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1783bd92d7feSAl Viro path_put(&nd->path); 1784bd23a539SAl Viro err = -ENOTDIR; 1785bd92d7feSAl Viro } 1786bd92d7feSAl Viro } 178716c2cd71SAl Viro 178870e9b357SAl Viro if (base) 178970e9b357SAl Viro fput(base); 1790ee0827cdSAl Viro 17915b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 179231e6b01fSNick Piggin path_put(&nd->root); 179331e6b01fSNick Piggin nd->root.mnt = NULL; 179431e6b01fSNick Piggin } 1795bd92d7feSAl Viro return err; 179631e6b01fSNick Piggin } 179731e6b01fSNick Piggin 1798ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1799ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1800ee0827cdSAl Viro { 1801ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1802ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1803ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1804ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1805ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1806ee0827cdSAl Viro 180731e6b01fSNick Piggin if (likely(!retval)) { 180831e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 180931e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 181031e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 181131e6b01fSNick Piggin } 181231e6b01fSNick Piggin } 1813170aa3d0SUlrich Drepper return retval; 18141da177e4SLinus Torvalds } 18151da177e4SLinus Torvalds 1816c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 18175590ff0dSUlrich Drepper { 1818c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 18195590ff0dSUlrich Drepper } 18205590ff0dSUlrich Drepper 1821d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1822d1811465SAl Viro { 1823d1811465SAl Viro struct nameidata nd; 1824d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1825d1811465SAl Viro if (!res) 1826d1811465SAl Viro *path = nd.path; 1827d1811465SAl Viro return res; 1828d1811465SAl Viro } 1829d1811465SAl Viro 183016f18200SJosef 'Jeff' Sipek /** 183116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 183216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 183316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 183416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 183516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1836e0a01249SAl Viro * @path: pointer to struct path to fill 183716f18200SJosef 'Jeff' Sipek */ 183816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 183916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1840e0a01249SAl Viro struct path *path) 184116f18200SJosef 'Jeff' Sipek { 1842e0a01249SAl Viro struct nameidata nd; 1843e0a01249SAl Viro int err; 1844e0a01249SAl Viro nd.root.dentry = dentry; 1845e0a01249SAl Viro nd.root.mnt = mnt; 1846e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18475b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1848e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1849e0a01249SAl Viro if (!err) 1850e0a01249SAl Viro *path = nd.path; 1851e0a01249SAl Viro return err; 185216f18200SJosef 'Jeff' Sipek } 185316f18200SJosef 'Jeff' Sipek 1854057f6c01SJames Morris /* 1855057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1856057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1857057f6c01SJames Morris * SMP-safe. 1858057f6c01SJames Morris */ 1859a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 18601da177e4SLinus Torvalds { 18614ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 18621da177e4SLinus Torvalds } 18631da177e4SLinus Torvalds 1864eead1911SChristoph Hellwig /** 1865a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1866eead1911SChristoph Hellwig * @name: pathname component to lookup 1867eead1911SChristoph Hellwig * @base: base directory to lookup from 1868eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1869eead1911SChristoph Hellwig * 1870a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1871a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1872eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1873eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1874eead1911SChristoph Hellwig */ 1875057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1876057f6c01SJames Morris { 1877057f6c01SJames Morris struct qstr this; 18786a96ba54SAl Viro unsigned int c; 1879cda309deSMiklos Szeredi int err; 1880057f6c01SJames Morris 18812f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 18822f9092e1SDavid Woodhouse 18836a96ba54SAl Viro this.name = name; 18846a96ba54SAl Viro this.len = len; 18850145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 18866a96ba54SAl Viro if (!len) 18876a96ba54SAl Viro return ERR_PTR(-EACCES); 18886a96ba54SAl Viro 18896a96ba54SAl Viro while (len--) { 18906a96ba54SAl Viro c = *(const unsigned char *)name++; 18916a96ba54SAl Viro if (c == '/' || c == '\0') 18926a96ba54SAl Viro return ERR_PTR(-EACCES); 18936a96ba54SAl Viro } 18945a202bcdSAl Viro /* 18955a202bcdSAl Viro * See if the low-level filesystem might want 18965a202bcdSAl Viro * to use its own hash.. 18975a202bcdSAl Viro */ 18985a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 18995a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 19005a202bcdSAl Viro if (err < 0) 19015a202bcdSAl Viro return ERR_PTR(err); 19025a202bcdSAl Viro } 1903eead1911SChristoph Hellwig 1904cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 1905cda309deSMiklos Szeredi if (err) 1906cda309deSMiklos Szeredi return ERR_PTR(err); 1907cda309deSMiklos Szeredi 190849705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1909057f6c01SJames Morris } 1910057f6c01SJames Morris 19111fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 19121fa1e7f6SAndy Whitcroft struct path *path, int *empty) 19131da177e4SLinus Torvalds { 19142d8f3038SAl Viro struct nameidata nd; 19151fa1e7f6SAndy Whitcroft char *tmp = getname_flags(name, flags, empty); 19161da177e4SLinus Torvalds int err = PTR_ERR(tmp); 19171da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 19182d8f3038SAl Viro 19192d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 19202d8f3038SAl Viro 19212d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 19221da177e4SLinus Torvalds putname(tmp); 19232d8f3038SAl Viro if (!err) 19242d8f3038SAl Viro *path = nd.path; 19251da177e4SLinus Torvalds } 19261da177e4SLinus Torvalds return err; 19271da177e4SLinus Torvalds } 19281da177e4SLinus Torvalds 19291fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 19301fa1e7f6SAndy Whitcroft struct path *path) 19311fa1e7f6SAndy Whitcroft { 1932f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 19331fa1e7f6SAndy Whitcroft } 19341fa1e7f6SAndy Whitcroft 19352ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 19362ad94ae6SAl Viro struct nameidata *nd, char **name) 19372ad94ae6SAl Viro { 19382ad94ae6SAl Viro char *s = getname(path); 19392ad94ae6SAl Viro int error; 19402ad94ae6SAl Viro 19412ad94ae6SAl Viro if (IS_ERR(s)) 19422ad94ae6SAl Viro return PTR_ERR(s); 19432ad94ae6SAl Viro 19442ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 19452ad94ae6SAl Viro if (error) 19462ad94ae6SAl Viro putname(s); 19472ad94ae6SAl Viro else 19482ad94ae6SAl Viro *name = s; 19492ad94ae6SAl Viro 19502ad94ae6SAl Viro return error; 19512ad94ae6SAl Viro } 19522ad94ae6SAl Viro 19531da177e4SLinus Torvalds /* 19541da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 19551da177e4SLinus Torvalds * minimal. 19561da177e4SLinus Torvalds */ 19571da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 19581da177e4SLinus Torvalds { 19598e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 1960da9592edSDavid Howells 19611da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 19621da177e4SLinus Torvalds return 0; 19638e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 19641da177e4SLinus Torvalds return 0; 19658e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 19661da177e4SLinus Torvalds return 0; 19671a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 19681da177e4SLinus Torvalds } 19691da177e4SLinus Torvalds 19701da177e4SLinus Torvalds /* 19711da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 19721da177e4SLinus Torvalds * whether the type of victim is right. 19731da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 19741da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 19751da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 19761da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 19771da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 19781da177e4SLinus Torvalds * a. be owner of dir, or 19791da177e4SLinus Torvalds * b. be owner of victim, or 19801da177e4SLinus Torvalds * c. have CAP_FOWNER capability 19811da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 19821da177e4SLinus Torvalds * links pointing to it. 19831da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 19841da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 19851da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 19861da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 19871da177e4SLinus Torvalds * nfs_async_unlink(). 19881da177e4SLinus Torvalds */ 1989858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 19901da177e4SLinus Torvalds { 19911da177e4SLinus Torvalds int error; 19921da177e4SLinus Torvalds 19931da177e4SLinus Torvalds if (!victim->d_inode) 19941da177e4SLinus Torvalds return -ENOENT; 19951da177e4SLinus Torvalds 19961da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1997cccc6bbaSAl Viro audit_inode_child(victim, dir); 19981da177e4SLinus Torvalds 1999f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 20001da177e4SLinus Torvalds if (error) 20011da177e4SLinus Torvalds return error; 20021da177e4SLinus Torvalds if (IS_APPEND(dir)) 20031da177e4SLinus Torvalds return -EPERM; 20041da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2005f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 20061da177e4SLinus Torvalds return -EPERM; 20071da177e4SLinus Torvalds if (isdir) { 20081da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 20091da177e4SLinus Torvalds return -ENOTDIR; 20101da177e4SLinus Torvalds if (IS_ROOT(victim)) 20111da177e4SLinus Torvalds return -EBUSY; 20121da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 20131da177e4SLinus Torvalds return -EISDIR; 20141da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20151da177e4SLinus Torvalds return -ENOENT; 20161da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 20171da177e4SLinus Torvalds return -EBUSY; 20181da177e4SLinus Torvalds return 0; 20191da177e4SLinus Torvalds } 20201da177e4SLinus Torvalds 20211da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 20221da177e4SLinus Torvalds * dir. 20231da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 20241da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 20251da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 20261da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 20271da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 20281da177e4SLinus Torvalds */ 2029a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 20301da177e4SLinus Torvalds { 20311da177e4SLinus Torvalds if (child->d_inode) 20321da177e4SLinus Torvalds return -EEXIST; 20331da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 20341da177e4SLinus Torvalds return -ENOENT; 2035f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 20361da177e4SLinus Torvalds } 20371da177e4SLinus Torvalds 20381da177e4SLinus Torvalds /* 20391da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 20401da177e4SLinus Torvalds */ 20411da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 20421da177e4SLinus Torvalds { 20431da177e4SLinus Torvalds struct dentry *p; 20441da177e4SLinus Torvalds 20451da177e4SLinus Torvalds if (p1 == p2) { 2046f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 20471da177e4SLinus Torvalds return NULL; 20481da177e4SLinus Torvalds } 20491da177e4SLinus Torvalds 2050a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20511da177e4SLinus Torvalds 2052e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2053e2761a11SOGAWA Hirofumi if (p) { 2054f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2055f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 20561da177e4SLinus Torvalds return p; 20571da177e4SLinus Torvalds } 20581da177e4SLinus Torvalds 2059e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2060e2761a11SOGAWA Hirofumi if (p) { 2061f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2062f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20631da177e4SLinus Torvalds return p; 20641da177e4SLinus Torvalds } 20651da177e4SLinus Torvalds 2066f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2067f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 20681da177e4SLinus Torvalds return NULL; 20691da177e4SLinus Torvalds } 20701da177e4SLinus Torvalds 20711da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 20721da177e4SLinus Torvalds { 20731b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 20741da177e4SLinus Torvalds if (p1 != p2) { 20751b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2076a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 20771da177e4SLinus Torvalds } 20781da177e4SLinus Torvalds } 20791da177e4SLinus Torvalds 20804acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 20811da177e4SLinus Torvalds struct nameidata *nd) 20821da177e4SLinus Torvalds { 2083a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 20841da177e4SLinus Torvalds 20851da177e4SLinus Torvalds if (error) 20861da177e4SLinus Torvalds return error; 20871da177e4SLinus Torvalds 2088acfa4380SAl Viro if (!dir->i_op->create) 20891da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 20901da177e4SLinus Torvalds mode &= S_IALLUGO; 20911da177e4SLinus Torvalds mode |= S_IFREG; 20921da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 20931da177e4SLinus Torvalds if (error) 20941da177e4SLinus Torvalds return error; 20951da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 2096a74574aaSStephen Smalley if (!error) 2097f38aa942SAmy Griffis fsnotify_create(dir, dentry); 20981da177e4SLinus Torvalds return error; 20991da177e4SLinus Torvalds } 21001da177e4SLinus Torvalds 210173d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 21021da177e4SLinus Torvalds { 21033fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 21041da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 21051da177e4SLinus Torvalds int error; 21061da177e4SLinus Torvalds 2107bcda7652SAl Viro /* O_PATH? */ 2108bcda7652SAl Viro if (!acc_mode) 2109bcda7652SAl Viro return 0; 2110bcda7652SAl Viro 21111da177e4SLinus Torvalds if (!inode) 21121da177e4SLinus Torvalds return -ENOENT; 21131da177e4SLinus Torvalds 2114c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2115c8fe8f30SChristoph Hellwig case S_IFLNK: 21161da177e4SLinus Torvalds return -ELOOP; 2117c8fe8f30SChristoph Hellwig case S_IFDIR: 2118c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 21191da177e4SLinus Torvalds return -EISDIR; 2120c8fe8f30SChristoph Hellwig break; 2121c8fe8f30SChristoph Hellwig case S_IFBLK: 2122c8fe8f30SChristoph Hellwig case S_IFCHR: 21233fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 21241da177e4SLinus Torvalds return -EACCES; 2125c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2126c8fe8f30SChristoph Hellwig case S_IFIFO: 2127c8fe8f30SChristoph Hellwig case S_IFSOCK: 21281da177e4SLinus Torvalds flag &= ~O_TRUNC; 2129c8fe8f30SChristoph Hellwig break; 21304a3fd211SDave Hansen } 2131b41572e9SDave Hansen 21323fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2133b41572e9SDave Hansen if (error) 2134b41572e9SDave Hansen return error; 21356146f0d5SMimi Zohar 21361da177e4SLinus Torvalds /* 21371da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 21381da177e4SLinus Torvalds */ 21391da177e4SLinus Torvalds if (IS_APPEND(inode)) { 21408737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 21417715b521SAl Viro return -EPERM; 21421da177e4SLinus Torvalds if (flag & O_TRUNC) 21437715b521SAl Viro return -EPERM; 21441da177e4SLinus Torvalds } 21451da177e4SLinus Torvalds 21461da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 21472e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 21487715b521SAl Viro return -EPERM; 21491da177e4SLinus Torvalds 2150f3c7691eSJ. Bruce Fields return 0; 21517715b521SAl Viro } 21527715b521SAl Viro 2153e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 21547715b521SAl Viro { 2155e1181ee6SJeff Layton struct path *path = &filp->f_path; 21567715b521SAl Viro struct inode *inode = path->dentry->d_inode; 21577715b521SAl Viro int error = get_write_access(inode); 21581da177e4SLinus Torvalds if (error) 21597715b521SAl Viro return error; 21601da177e4SLinus Torvalds /* 21611da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 21621da177e4SLinus Torvalds */ 21631da177e4SLinus Torvalds error = locks_verify_locked(inode); 2164be6d3e56SKentaro Takeda if (!error) 2165ea0d3ab2STetsuo Handa error = security_path_truncate(path); 21661da177e4SLinus Torvalds if (!error) { 21677715b521SAl Viro error = do_truncate(path->dentry, 0, 2168d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2169e1181ee6SJeff Layton filp); 21701da177e4SLinus Torvalds } 21711da177e4SLinus Torvalds put_write_access(inode); 2172acd0c935SMimi Zohar return error; 21731da177e4SLinus Torvalds } 21741da177e4SLinus Torvalds 2175d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2176d57999e1SDave Hansen { 21778a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 21788a5e929dSAl Viro flag--; 2179d57999e1SDave Hansen return flag; 2180d57999e1SDave Hansen } 2181d57999e1SDave Hansen 218231e6b01fSNick Piggin /* 2183fe2d35ffSAl Viro * Handle the last step of open() 218431e6b01fSNick Piggin */ 2185fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2186c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2187fb1cc555SAl Viro { 2188a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 21896c0d46c4SAl Viro struct dentry *dentry; 2190ca344a89SAl Viro int open_flag = op->open_flag; 21916c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2192ca344a89SAl Viro int want_write = 0; 2193bcda7652SAl Viro int acc_mode = op->acc_mode; 2194fb1cc555SAl Viro struct file *filp; 219516c2cd71SAl Viro int error; 2196fb1cc555SAl Viro 2197c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2198c3e380b0SAl Viro nd->flags |= op->intent; 2199c3e380b0SAl Viro 22001f36f774SAl Viro switch (nd->last_type) { 22011f36f774SAl Viro case LAST_DOTDOT: 2202176306f5SNeil Brown case LAST_DOT: 2203fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2204fe2d35ffSAl Viro if (error) 2205fe2d35ffSAl Viro return ERR_PTR(error); 22061f36f774SAl Viro /* fallthrough */ 22071f36f774SAl Viro case LAST_ROOT: 22089f1fafeeSAl Viro error = complete_walk(nd); 220916c2cd71SAl Viro if (error) 22109f1fafeeSAl Viro return ERR_PTR(error); 2211fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2212ca344a89SAl Viro if (open_flag & O_CREAT) { 221316c2cd71SAl Viro error = -EISDIR; 22141f36f774SAl Viro goto exit; 2215fe2d35ffSAl Viro } 2216fe2d35ffSAl Viro goto ok; 22171f36f774SAl Viro case LAST_BIND: 22189f1fafeeSAl Viro error = complete_walk(nd); 221916c2cd71SAl Viro if (error) 22209f1fafeeSAl Viro return ERR_PTR(error); 22211f36f774SAl Viro audit_inode(pathname, dir); 22221f36f774SAl Viro goto ok; 22231f36f774SAl Viro } 2224a2c36b45SAl Viro 2225ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2226bcda7652SAl Viro int symlink_ok = 0; 2227fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2228fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2229bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2230bcda7652SAl Viro symlink_ok = 1; 2231fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2232ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2233ce57dfc1SAl Viro !symlink_ok); 2234ce57dfc1SAl Viro if (error < 0) 2235fe2d35ffSAl Viro return ERR_PTR(error); 2236ce57dfc1SAl Viro if (error) /* symlink */ 2237fe2d35ffSAl Viro return NULL; 2238fe2d35ffSAl Viro /* sayonara */ 22399f1fafeeSAl Viro error = complete_walk(nd); 22409f1fafeeSAl Viro if (error) 22417f6c7e62SMiklos Szeredi return ERR_PTR(error); 2242fe2d35ffSAl Viro 2243fe2d35ffSAl Viro error = -ENOTDIR; 2244fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2245ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2246fe2d35ffSAl Viro goto exit; 2247fe2d35ffSAl Viro } 2248fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2249fe2d35ffSAl Viro goto ok; 2250fe2d35ffSAl Viro } 2251fe2d35ffSAl Viro 2252fe2d35ffSAl Viro /* create side of things */ 2253a3fbbde7SAl Viro /* 2254a3fbbde7SAl Viro * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been 2255a3fbbde7SAl Viro * cleared when we got to the last component we are about to look up 2256a3fbbde7SAl Viro */ 22579f1fafeeSAl Viro error = complete_walk(nd); 22589f1fafeeSAl Viro if (error) 22599f1fafeeSAl Viro return ERR_PTR(error); 2260fe2d35ffSAl Viro 2261fe2d35ffSAl Viro audit_inode(pathname, dir); 226216c2cd71SAl Viro error = -EISDIR; 22631f36f774SAl Viro /* trailing slashes? */ 226431e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 22651f36f774SAl Viro goto exit; 22661f36f774SAl Viro 2267a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2268a1e28038SAl Viro 22696c0d46c4SAl Viro dentry = lookup_hash(nd); 22706c0d46c4SAl Viro error = PTR_ERR(dentry); 22716c0d46c4SAl Viro if (IS_ERR(dentry)) { 2272fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2273fb1cc555SAl Viro goto exit; 2274fb1cc555SAl Viro } 2275fb1cc555SAl Viro 22766c0d46c4SAl Viro path->dentry = dentry; 22776c0d46c4SAl Viro path->mnt = nd->path.mnt; 22786c0d46c4SAl Viro 2279fb1cc555SAl Viro /* Negative dentry, just create the file */ 22806c0d46c4SAl Viro if (!dentry->d_inode) { 2281a218d0fdSAl Viro umode_t mode = op->mode; 22826c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 22836c0d46c4SAl Viro mode &= ~current_umask(); 2284fb1cc555SAl Viro /* 2285fb1cc555SAl Viro * This write is needed to ensure that a 22866c0d46c4SAl Viro * rw->ro transition does not occur between 2287fb1cc555SAl Viro * the time when the file is created and when 2288fb1cc555SAl Viro * a permanent write count is taken through 2289fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2290fb1cc555SAl Viro */ 2291fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2292fb1cc555SAl Viro if (error) 2293fb1cc555SAl Viro goto exit_mutex_unlock; 2294ca344a89SAl Viro want_write = 1; 22959b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2296ca344a89SAl Viro open_flag &= ~O_TRUNC; 22976c0d46c4SAl Viro will_truncate = 0; 2298bcda7652SAl Viro acc_mode = MAY_OPEN; 22996c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 23006c0d46c4SAl Viro if (error) 23016c0d46c4SAl Viro goto exit_mutex_unlock; 23026c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 23036c0d46c4SAl Viro if (error) 23046c0d46c4SAl Viro goto exit_mutex_unlock; 23056c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 23066c0d46c4SAl Viro dput(nd->path.dentry); 23076c0d46c4SAl Viro nd->path.dentry = dentry; 2308ca344a89SAl Viro goto common; 2309fb1cc555SAl Viro } 2310fb1cc555SAl Viro 2311fb1cc555SAl Viro /* 2312fb1cc555SAl Viro * It already exists. 2313fb1cc555SAl Viro */ 2314fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2315fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2316fb1cc555SAl Viro 2317fb1cc555SAl Viro error = -EEXIST; 2318ca344a89SAl Viro if (open_flag & O_EXCL) 2319fb1cc555SAl Viro goto exit_dput; 2320fb1cc555SAl Viro 23219875cf80SDavid Howells error = follow_managed(path, nd->flags); 23229875cf80SDavid Howells if (error < 0) 2323fb1cc555SAl Viro goto exit_dput; 2324fb1cc555SAl Viro 2325a3fbbde7SAl Viro if (error) 2326a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2327a3fbbde7SAl Viro 2328fb1cc555SAl Viro error = -ENOENT; 2329fb1cc555SAl Viro if (!path->dentry->d_inode) 2330fb1cc555SAl Viro goto exit_dput; 23319e67f361SAl Viro 23329e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2333fb1cc555SAl Viro return NULL; 2334fb1cc555SAl Viro 2335fb1cc555SAl Viro path_to_nameidata(path, nd); 233631e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2337a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 2338a3fbbde7SAl Viro error = complete_walk(nd); 2339a3fbbde7SAl Viro if (error) 2340097b180cSMiklos Szeredi return ERR_PTR(error); 2341fb1cc555SAl Viro error = -EISDIR; 234231e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2343fb1cc555SAl Viro goto exit; 234467ee3ad2SAl Viro ok: 23456c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 23466c0d46c4SAl Viro will_truncate = 0; 23476c0d46c4SAl Viro 23480f9d1a10SAl Viro if (will_truncate) { 23490f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 23500f9d1a10SAl Viro if (error) 23510f9d1a10SAl Viro goto exit; 2352ca344a89SAl Viro want_write = 1; 23530f9d1a10SAl Viro } 2354ca344a89SAl Viro common: 2355bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2356ca344a89SAl Viro if (error) 23570f9d1a10SAl Viro goto exit; 23580f9d1a10SAl Viro filp = nameidata_to_filp(nd); 23590f9d1a10SAl Viro if (!IS_ERR(filp)) { 23600f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 23610f9d1a10SAl Viro if (error) { 23620f9d1a10SAl Viro fput(filp); 23630f9d1a10SAl Viro filp = ERR_PTR(error); 23640f9d1a10SAl Viro } 23650f9d1a10SAl Viro } 23660f9d1a10SAl Viro if (!IS_ERR(filp)) { 23670f9d1a10SAl Viro if (will_truncate) { 23680f9d1a10SAl Viro error = handle_truncate(filp); 23690f9d1a10SAl Viro if (error) { 23700f9d1a10SAl Viro fput(filp); 23710f9d1a10SAl Viro filp = ERR_PTR(error); 23720f9d1a10SAl Viro } 23730f9d1a10SAl Viro } 23740f9d1a10SAl Viro } 2375ca344a89SAl Viro out: 2376ca344a89SAl Viro if (want_write) 23770f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 23780f9d1a10SAl Viro path_put(&nd->path); 2379fb1cc555SAl Viro return filp; 2380fb1cc555SAl Viro 2381fb1cc555SAl Viro exit_mutex_unlock: 2382fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2383fb1cc555SAl Viro exit_dput: 2384fb1cc555SAl Viro path_put_conditional(path, nd); 2385fb1cc555SAl Viro exit: 2386ca344a89SAl Viro filp = ERR_PTR(error); 2387ca344a89SAl Viro goto out; 2388fb1cc555SAl Viro } 2389fb1cc555SAl Viro 239013aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 239173d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 23921da177e4SLinus Torvalds { 2393fe2d35ffSAl Viro struct file *base = NULL; 23944a3fd211SDave Hansen struct file *filp; 23959850c056SAl Viro struct path path; 239613aab428SAl Viro int error; 239731e6b01fSNick Piggin 239831e6b01fSNick Piggin filp = get_empty_filp(); 239931e6b01fSNick Piggin if (!filp) 240031e6b01fSNick Piggin return ERR_PTR(-ENFILE); 240131e6b01fSNick Piggin 240247c805dcSAl Viro filp->f_flags = op->open_flag; 240373d049a4SAl Viro nd->intent.open.file = filp; 240473d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 240573d049a4SAl Viro nd->intent.open.create_mode = op->mode; 240631e6b01fSNick Piggin 240773d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 240831e6b01fSNick Piggin if (unlikely(error)) 240913aab428SAl Viro goto out_filp; 241031e6b01fSNick Piggin 2411fe2d35ffSAl Viro current->total_link_count = 0; 241273d049a4SAl Viro error = link_path_walk(pathname, nd); 241331e6b01fSNick Piggin if (unlikely(error)) 241431e6b01fSNick Piggin goto out_filp; 24151da177e4SLinus Torvalds 241673d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2417806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 24187b9337aaSNick Piggin struct path link = path; 2419def4af30SAl Viro void *cookie; 2420574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 242173d049a4SAl Viro path_put_conditional(&path, nd); 242273d049a4SAl Viro path_put(&nd->path); 242340b39136SAl Viro filp = ERR_PTR(-ELOOP); 242440b39136SAl Viro break; 242540b39136SAl Viro } 242673d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 242773d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2428574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2429c3e380b0SAl Viro if (unlikely(error)) 2430f1afe9efSAl Viro filp = ERR_PTR(error); 2431c3e380b0SAl Viro else 243273d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2433574197e0SAl Viro put_link(nd, &link, cookie); 2434806b681cSAl Viro } 243510fa8e62SAl Viro out: 243673d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 243773d049a4SAl Viro path_put(&nd->root); 2438fe2d35ffSAl Viro if (base) 2439fe2d35ffSAl Viro fput(base); 244073d049a4SAl Viro release_open_intent(nd); 244110fa8e62SAl Viro return filp; 24421da177e4SLinus Torvalds 244331e6b01fSNick Piggin out_filp: 244410fa8e62SAl Viro filp = ERR_PTR(error); 244510fa8e62SAl Viro goto out; 2446de459215SKirill Korotaev } 24471da177e4SLinus Torvalds 244813aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 244913aab428SAl Viro const struct open_flags *op, int flags) 245013aab428SAl Viro { 245173d049a4SAl Viro struct nameidata nd; 245213aab428SAl Viro struct file *filp; 245313aab428SAl Viro 245473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 245513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 245673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 245713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 245873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 245913aab428SAl Viro return filp; 246013aab428SAl Viro } 246113aab428SAl Viro 246273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 246373d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 246473d049a4SAl Viro { 246573d049a4SAl Viro struct nameidata nd; 246673d049a4SAl Viro struct file *file; 246773d049a4SAl Viro 246873d049a4SAl Viro nd.root.mnt = mnt; 246973d049a4SAl Viro nd.root.dentry = dentry; 247073d049a4SAl Viro 247173d049a4SAl Viro flags |= LOOKUP_ROOT; 247273d049a4SAl Viro 2473bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 247473d049a4SAl Viro return ERR_PTR(-ELOOP); 247573d049a4SAl Viro 247673d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 247773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 247873d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 247973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 248073d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 248173d049a4SAl Viro return file; 248273d049a4SAl Viro } 248373d049a4SAl Viro 2484ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 24851da177e4SLinus Torvalds { 2486c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2487ed75e95dSAl Viro struct nameidata nd; 2488ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2489ed75e95dSAl Viro if (error) 2490ed75e95dSAl Viro return ERR_PTR(error); 24911da177e4SLinus Torvalds 2492c663e5d8SChristoph Hellwig /* 2493c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2494c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2495c663e5d8SChristoph Hellwig */ 2496ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2497ed75e95dSAl Viro goto out; 2498ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2499ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2500ed75e95dSAl Viro nd.intent.open.flags = O_EXCL; 2501c663e5d8SChristoph Hellwig 2502c663e5d8SChristoph Hellwig /* 2503c663e5d8SChristoph Hellwig * Do the final lookup. 2504c663e5d8SChristoph Hellwig */ 2505ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2506ed75e95dSAl Viro dentry = lookup_hash(&nd); 25071da177e4SLinus Torvalds if (IS_ERR(dentry)) 25081da177e4SLinus Torvalds goto fail; 2509c663e5d8SChristoph Hellwig 2510e9baf6e5SAl Viro if (dentry->d_inode) 2511e9baf6e5SAl Viro goto eexist; 2512c663e5d8SChristoph Hellwig /* 2513c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2514c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2515c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2516c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2517c663e5d8SChristoph Hellwig */ 2518ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 25191da177e4SLinus Torvalds dput(dentry); 25201da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2521ed75e95dSAl Viro goto fail; 2522e9baf6e5SAl Viro } 2523ed75e95dSAl Viro *path = nd.path; 2524e9baf6e5SAl Viro return dentry; 2525e9baf6e5SAl Viro eexist: 2526e9baf6e5SAl Viro dput(dentry); 2527e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 25281da177e4SLinus Torvalds fail: 2529dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2530ed75e95dSAl Viro out: 2531dae6ad8fSAl Viro path_put(&nd.path); 2532ed75e95dSAl Viro return dentry; 2533dae6ad8fSAl Viro } 2534dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2535dae6ad8fSAl Viro 2536dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2537dae6ad8fSAl Viro { 2538dae6ad8fSAl Viro char *tmp = getname(pathname); 2539dae6ad8fSAl Viro struct dentry *res; 2540dae6ad8fSAl Viro if (IS_ERR(tmp)) 2541dae6ad8fSAl Viro return ERR_CAST(tmp); 2542dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2543dae6ad8fSAl Viro putname(tmp); 2544dae6ad8fSAl Viro return res; 2545dae6ad8fSAl Viro } 2546dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2547dae6ad8fSAl Viro 25481a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 25491da177e4SLinus Torvalds { 2550a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25511da177e4SLinus Torvalds 25521da177e4SLinus Torvalds if (error) 25531da177e4SLinus Torvalds return error; 25541da177e4SLinus Torvalds 2555975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 25561da177e4SLinus Torvalds return -EPERM; 25571da177e4SLinus Torvalds 2558acfa4380SAl Viro if (!dir->i_op->mknod) 25591da177e4SLinus Torvalds return -EPERM; 25601da177e4SLinus Torvalds 256108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 256208ce5f16SSerge E. Hallyn if (error) 256308ce5f16SSerge E. Hallyn return error; 256408ce5f16SSerge E. Hallyn 25651da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 25661da177e4SLinus Torvalds if (error) 25671da177e4SLinus Torvalds return error; 25681da177e4SLinus Torvalds 25691da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2570a74574aaSStephen Smalley if (!error) 2571f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25721da177e4SLinus Torvalds return error; 25731da177e4SLinus Torvalds } 25741da177e4SLinus Torvalds 2575f69aac00SAl Viro static int may_mknod(umode_t mode) 2576463c3197SDave Hansen { 2577463c3197SDave Hansen switch (mode & S_IFMT) { 2578463c3197SDave Hansen case S_IFREG: 2579463c3197SDave Hansen case S_IFCHR: 2580463c3197SDave Hansen case S_IFBLK: 2581463c3197SDave Hansen case S_IFIFO: 2582463c3197SDave Hansen case S_IFSOCK: 2583463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2584463c3197SDave Hansen return 0; 2585463c3197SDave Hansen case S_IFDIR: 2586463c3197SDave Hansen return -EPERM; 2587463c3197SDave Hansen default: 2588463c3197SDave Hansen return -EINVAL; 2589463c3197SDave Hansen } 2590463c3197SDave Hansen } 2591463c3197SDave Hansen 25928208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 25932e4d0924SHeiko Carstens unsigned, dev) 25941da177e4SLinus Torvalds { 25951da177e4SLinus Torvalds struct dentry *dentry; 2596dae6ad8fSAl Viro struct path path; 2597dae6ad8fSAl Viro int error; 25981da177e4SLinus Torvalds 25991da177e4SLinus Torvalds if (S_ISDIR(mode)) 26001da177e4SLinus Torvalds return -EPERM; 26011da177e4SLinus Torvalds 2602dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2603dae6ad8fSAl Viro if (IS_ERR(dentry)) 2604dae6ad8fSAl Viro return PTR_ERR(dentry); 26052ad94ae6SAl Viro 2606dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2607ce3b0f8dSAl Viro mode &= ~current_umask(); 2608463c3197SDave Hansen error = may_mknod(mode); 2609463c3197SDave Hansen if (error) 2610463c3197SDave Hansen goto out_dput; 2611dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2612463c3197SDave Hansen if (error) 2613463c3197SDave Hansen goto out_dput; 2614dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2615be6d3e56SKentaro Takeda if (error) 2616be6d3e56SKentaro Takeda goto out_drop_write; 26171da177e4SLinus Torvalds switch (mode & S_IFMT) { 26181da177e4SLinus Torvalds case 0: case S_IFREG: 2619dae6ad8fSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); 26201da177e4SLinus Torvalds break; 26211da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2622dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 26231da177e4SLinus Torvalds new_decode_dev(dev)); 26241da177e4SLinus Torvalds break; 26251da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2626dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 26271da177e4SLinus Torvalds break; 26281da177e4SLinus Torvalds } 2629be6d3e56SKentaro Takeda out_drop_write: 2630dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2631463c3197SDave Hansen out_dput: 26321da177e4SLinus Torvalds dput(dentry); 2633dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2634dae6ad8fSAl Viro path_put(&path); 26351da177e4SLinus Torvalds 26361da177e4SLinus Torvalds return error; 26371da177e4SLinus Torvalds } 26381da177e4SLinus Torvalds 26398208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 26405590ff0dSUlrich Drepper { 26415590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 26425590ff0dSUlrich Drepper } 26435590ff0dSUlrich Drepper 264418bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 26451da177e4SLinus Torvalds { 2646a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26478de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 26481da177e4SLinus Torvalds 26491da177e4SLinus Torvalds if (error) 26501da177e4SLinus Torvalds return error; 26511da177e4SLinus Torvalds 2652acfa4380SAl Viro if (!dir->i_op->mkdir) 26531da177e4SLinus Torvalds return -EPERM; 26541da177e4SLinus Torvalds 26551da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 26561da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 26571da177e4SLinus Torvalds if (error) 26581da177e4SLinus Torvalds return error; 26591da177e4SLinus Torvalds 26608de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 26618de52778SAl Viro return -EMLINK; 26628de52778SAl Viro 26631da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2664a74574aaSStephen Smalley if (!error) 2665f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 26661da177e4SLinus Torvalds return error; 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds 2669a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 26701da177e4SLinus Torvalds { 26716902d925SDave Hansen struct dentry *dentry; 2672dae6ad8fSAl Viro struct path path; 2673dae6ad8fSAl Viro int error; 26741da177e4SLinus Torvalds 2675dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 26766902d925SDave Hansen if (IS_ERR(dentry)) 2677dae6ad8fSAl Viro return PTR_ERR(dentry); 26786902d925SDave Hansen 2679dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2680ce3b0f8dSAl Viro mode &= ~current_umask(); 2681dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2682463c3197SDave Hansen if (error) 2683463c3197SDave Hansen goto out_dput; 2684dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 2685be6d3e56SKentaro Takeda if (error) 2686be6d3e56SKentaro Takeda goto out_drop_write; 2687dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 2688be6d3e56SKentaro Takeda out_drop_write: 2689dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2690463c3197SDave Hansen out_dput: 26911da177e4SLinus Torvalds dput(dentry); 2692dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2693dae6ad8fSAl Viro path_put(&path); 26941da177e4SLinus Torvalds return error; 26951da177e4SLinus Torvalds } 26961da177e4SLinus Torvalds 2697a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 26985590ff0dSUlrich Drepper { 26995590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 27005590ff0dSUlrich Drepper } 27015590ff0dSUlrich Drepper 27021da177e4SLinus Torvalds /* 2703a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2704c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 2705a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2706a71905f0SSage Weil * then we drop the dentry now. 27071da177e4SLinus Torvalds * 27081da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 27091da177e4SLinus Torvalds * do a 27101da177e4SLinus Torvalds * 27111da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 27121da177e4SLinus Torvalds * return -EBUSY; 27131da177e4SLinus Torvalds * 27141da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 27151da177e4SLinus Torvalds * that is still in use by something else.. 27161da177e4SLinus Torvalds */ 27171da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 27181da177e4SLinus Torvalds { 27191da177e4SLinus Torvalds shrink_dcache_parent(dentry); 27201da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 272164252c75SSage Weil if (dentry->d_count == 1) 27221da177e4SLinus Torvalds __d_drop(dentry); 27231da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 27241da177e4SLinus Torvalds } 27251da177e4SLinus Torvalds 27261da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 27271da177e4SLinus Torvalds { 27281da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 27291da177e4SLinus Torvalds 27301da177e4SLinus Torvalds if (error) 27311da177e4SLinus Torvalds return error; 27321da177e4SLinus Torvalds 2733acfa4380SAl Viro if (!dir->i_op->rmdir) 27341da177e4SLinus Torvalds return -EPERM; 27351da177e4SLinus Torvalds 27361d2ef590SAl Viro dget(dentry); 27371b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2738912dbc15SSage Weil 27391da177e4SLinus Torvalds error = -EBUSY; 2740912dbc15SSage Weil if (d_mountpoint(dentry)) 2741912dbc15SSage Weil goto out; 2742912dbc15SSage Weil 27431da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2744912dbc15SSage Weil if (error) 2745912dbc15SSage Weil goto out; 2746912dbc15SSage Weil 27473cebde24SSage Weil shrink_dcache_parent(dentry); 27481da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2749912dbc15SSage Weil if (error) 2750912dbc15SSage Weil goto out; 2751912dbc15SSage Weil 27521da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2753d83c49f3SAl Viro dont_mount(dentry); 27541da177e4SLinus Torvalds 2755912dbc15SSage Weil out: 2756912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 27571d2ef590SAl Viro dput(dentry); 2758912dbc15SSage Weil if (!error) 2759912dbc15SSage Weil d_delete(dentry); 27601da177e4SLinus Torvalds return error; 27611da177e4SLinus Torvalds } 27621da177e4SLinus Torvalds 27635590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 27641da177e4SLinus Torvalds { 27651da177e4SLinus Torvalds int error = 0; 27661da177e4SLinus Torvalds char * name; 27671da177e4SLinus Torvalds struct dentry *dentry; 27681da177e4SLinus Torvalds struct nameidata nd; 27691da177e4SLinus Torvalds 27702ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27711da177e4SLinus Torvalds if (error) 27722ad94ae6SAl Viro return error; 27731da177e4SLinus Torvalds 27741da177e4SLinus Torvalds switch(nd.last_type) { 27751da177e4SLinus Torvalds case LAST_DOTDOT: 27761da177e4SLinus Torvalds error = -ENOTEMPTY; 27771da177e4SLinus Torvalds goto exit1; 27781da177e4SLinus Torvalds case LAST_DOT: 27791da177e4SLinus Torvalds error = -EINVAL; 27801da177e4SLinus Torvalds goto exit1; 27811da177e4SLinus Torvalds case LAST_ROOT: 27821da177e4SLinus Torvalds error = -EBUSY; 27831da177e4SLinus Torvalds goto exit1; 27841da177e4SLinus Torvalds } 27850612d9fbSOGAWA Hirofumi 27860612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27870612d9fbSOGAWA Hirofumi 27884ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 278949705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27901da177e4SLinus Torvalds error = PTR_ERR(dentry); 27916902d925SDave Hansen if (IS_ERR(dentry)) 27926902d925SDave Hansen goto exit2; 2793e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2794e6bc45d6STheodore Ts'o error = -ENOENT; 2795e6bc45d6STheodore Ts'o goto exit3; 2796e6bc45d6STheodore Ts'o } 27970622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27980622753bSDave Hansen if (error) 27990622753bSDave Hansen goto exit3; 2800be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2801be6d3e56SKentaro Takeda if (error) 2802be6d3e56SKentaro Takeda goto exit4; 28034ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2804be6d3e56SKentaro Takeda exit4: 28050622753bSDave Hansen mnt_drop_write(nd.path.mnt); 28060622753bSDave Hansen exit3: 28071da177e4SLinus Torvalds dput(dentry); 28086902d925SDave Hansen exit2: 28094ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 28101da177e4SLinus Torvalds exit1: 28111d957f9bSJan Blunck path_put(&nd.path); 28121da177e4SLinus Torvalds putname(name); 28131da177e4SLinus Torvalds return error; 28141da177e4SLinus Torvalds } 28151da177e4SLinus Torvalds 28163cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 28175590ff0dSUlrich Drepper { 28185590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 28195590ff0dSUlrich Drepper } 28205590ff0dSUlrich Drepper 28211da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 28221da177e4SLinus Torvalds { 28231da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 28241da177e4SLinus Torvalds 28251da177e4SLinus Torvalds if (error) 28261da177e4SLinus Torvalds return error; 28271da177e4SLinus Torvalds 2828acfa4380SAl Viro if (!dir->i_op->unlink) 28291da177e4SLinus Torvalds return -EPERM; 28301da177e4SLinus Torvalds 28311b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 28321da177e4SLinus Torvalds if (d_mountpoint(dentry)) 28331da177e4SLinus Torvalds error = -EBUSY; 28341da177e4SLinus Torvalds else { 28351da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2836bec1052eSAl Viro if (!error) { 28371da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2838bec1052eSAl Viro if (!error) 2839d83c49f3SAl Viro dont_mount(dentry); 2840bec1052eSAl Viro } 28411da177e4SLinus Torvalds } 28421b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 28431da177e4SLinus Torvalds 28441da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 28451da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2846ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 28471da177e4SLinus Torvalds d_delete(dentry); 28481da177e4SLinus Torvalds } 28490eeca283SRobert Love 28501da177e4SLinus Torvalds return error; 28511da177e4SLinus Torvalds } 28521da177e4SLinus Torvalds 28531da177e4SLinus Torvalds /* 28541da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 28551b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 28561da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 28571da177e4SLinus Torvalds * while waiting on the I/O. 28581da177e4SLinus Torvalds */ 28595590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 28601da177e4SLinus Torvalds { 28612ad94ae6SAl Viro int error; 28621da177e4SLinus Torvalds char *name; 28631da177e4SLinus Torvalds struct dentry *dentry; 28641da177e4SLinus Torvalds struct nameidata nd; 28651da177e4SLinus Torvalds struct inode *inode = NULL; 28661da177e4SLinus Torvalds 28672ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 28681da177e4SLinus Torvalds if (error) 28692ad94ae6SAl Viro return error; 28702ad94ae6SAl Viro 28711da177e4SLinus Torvalds error = -EISDIR; 28721da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 28731da177e4SLinus Torvalds goto exit1; 28740612d9fbSOGAWA Hirofumi 28750612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 28760612d9fbSOGAWA Hirofumi 28774ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 287849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 28791da177e4SLinus Torvalds error = PTR_ERR(dentry); 28801da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 28811da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 288250338b88STörök Edwin if (nd.last.name[nd.last.len]) 288350338b88STörök Edwin goto slashes; 28841da177e4SLinus Torvalds inode = dentry->d_inode; 288550338b88STörök Edwin if (!inode) 2886e6bc45d6STheodore Ts'o goto slashes; 28877de9c6eeSAl Viro ihold(inode); 28880622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 28890622753bSDave Hansen if (error) 28900622753bSDave Hansen goto exit2; 2891be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2892be6d3e56SKentaro Takeda if (error) 2893be6d3e56SKentaro Takeda goto exit3; 28944ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2895be6d3e56SKentaro Takeda exit3: 28960622753bSDave Hansen mnt_drop_write(nd.path.mnt); 28971da177e4SLinus Torvalds exit2: 28981da177e4SLinus Torvalds dput(dentry); 28991da177e4SLinus Torvalds } 29004ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 29011da177e4SLinus Torvalds if (inode) 29021da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 29031da177e4SLinus Torvalds exit1: 29041d957f9bSJan Blunck path_put(&nd.path); 29051da177e4SLinus Torvalds putname(name); 29061da177e4SLinus Torvalds return error; 29071da177e4SLinus Torvalds 29081da177e4SLinus Torvalds slashes: 29091da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 29101da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 29111da177e4SLinus Torvalds goto exit2; 29121da177e4SLinus Torvalds } 29131da177e4SLinus Torvalds 29142e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 29155590ff0dSUlrich Drepper { 29165590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 29175590ff0dSUlrich Drepper return -EINVAL; 29185590ff0dSUlrich Drepper 29195590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 29205590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 29215590ff0dSUlrich Drepper 29225590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 29235590ff0dSUlrich Drepper } 29245590ff0dSUlrich Drepper 29253480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 29265590ff0dSUlrich Drepper { 29275590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 29285590ff0dSUlrich Drepper } 29295590ff0dSUlrich Drepper 2930db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 29311da177e4SLinus Torvalds { 2932a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 29331da177e4SLinus Torvalds 29341da177e4SLinus Torvalds if (error) 29351da177e4SLinus Torvalds return error; 29361da177e4SLinus Torvalds 2937acfa4380SAl Viro if (!dir->i_op->symlink) 29381da177e4SLinus Torvalds return -EPERM; 29391da177e4SLinus Torvalds 29401da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 29411da177e4SLinus Torvalds if (error) 29421da177e4SLinus Torvalds return error; 29431da177e4SLinus Torvalds 29441da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2945a74574aaSStephen Smalley if (!error) 2946f38aa942SAmy Griffis fsnotify_create(dir, dentry); 29471da177e4SLinus Torvalds return error; 29481da177e4SLinus Torvalds } 29491da177e4SLinus Torvalds 29502e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 29512e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 29521da177e4SLinus Torvalds { 29532ad94ae6SAl Viro int error; 29541da177e4SLinus Torvalds char *from; 29556902d925SDave Hansen struct dentry *dentry; 2956dae6ad8fSAl Viro struct path path; 29571da177e4SLinus Torvalds 29581da177e4SLinus Torvalds from = getname(oldname); 29591da177e4SLinus Torvalds if (IS_ERR(from)) 29601da177e4SLinus Torvalds return PTR_ERR(from); 29612ad94ae6SAl Viro 2962dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 29631da177e4SLinus Torvalds error = PTR_ERR(dentry); 29646902d925SDave Hansen if (IS_ERR(dentry)) 2965dae6ad8fSAl Viro goto out_putname; 29666902d925SDave Hansen 2967dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 296875c3f29dSDave Hansen if (error) 296975c3f29dSDave Hansen goto out_dput; 2970dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 2971be6d3e56SKentaro Takeda if (error) 2972be6d3e56SKentaro Takeda goto out_drop_write; 2973dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 2974be6d3e56SKentaro Takeda out_drop_write: 2975dae6ad8fSAl Viro mnt_drop_write(path.mnt); 297675c3f29dSDave Hansen out_dput: 29771da177e4SLinus Torvalds dput(dentry); 2978dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2979dae6ad8fSAl Viro path_put(&path); 29806902d925SDave Hansen out_putname: 29811da177e4SLinus Torvalds putname(from); 29821da177e4SLinus Torvalds return error; 29831da177e4SLinus Torvalds } 29841da177e4SLinus Torvalds 29853480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 29865590ff0dSUlrich Drepper { 29875590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 29885590ff0dSUlrich Drepper } 29895590ff0dSUlrich Drepper 29901da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 29911da177e4SLinus Torvalds { 29921da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 29938de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 29941da177e4SLinus Torvalds int error; 29951da177e4SLinus Torvalds 29961da177e4SLinus Torvalds if (!inode) 29971da177e4SLinus Torvalds return -ENOENT; 29981da177e4SLinus Torvalds 2999a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 30001da177e4SLinus Torvalds if (error) 30011da177e4SLinus Torvalds return error; 30021da177e4SLinus Torvalds 30031da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 30041da177e4SLinus Torvalds return -EXDEV; 30051da177e4SLinus Torvalds 30061da177e4SLinus Torvalds /* 30071da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 30081da177e4SLinus Torvalds */ 30091da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 30101da177e4SLinus Torvalds return -EPERM; 3011acfa4380SAl Viro if (!dir->i_op->link) 30121da177e4SLinus Torvalds return -EPERM; 30137e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 30141da177e4SLinus Torvalds return -EPERM; 30151da177e4SLinus Torvalds 30161da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 30171da177e4SLinus Torvalds if (error) 30181da177e4SLinus Torvalds return error; 30191da177e4SLinus Torvalds 30207e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3021aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3022aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 3023aae8a97dSAneesh Kumar K.V error = -ENOENT; 30248de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 30258de52778SAl Viro error = -EMLINK; 3026aae8a97dSAneesh Kumar K.V else 30271da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 30287e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3029e31e14ecSStephen Smalley if (!error) 30307e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 30311da177e4SLinus Torvalds return error; 30321da177e4SLinus Torvalds } 30331da177e4SLinus Torvalds 30341da177e4SLinus Torvalds /* 30351da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 30361da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 30371da177e4SLinus Torvalds * newname. --KAB 30381da177e4SLinus Torvalds * 30391da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 30401da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 30411da177e4SLinus Torvalds * and other special files. --ADM 30421da177e4SLinus Torvalds */ 30432e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 30442e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 30451da177e4SLinus Torvalds { 30461da177e4SLinus Torvalds struct dentry *new_dentry; 3047dae6ad8fSAl Viro struct path old_path, new_path; 304811a7b371SAneesh Kumar K.V int how = 0; 30491da177e4SLinus Torvalds int error; 30501da177e4SLinus Torvalds 305111a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3052c04030e1SUlrich Drepper return -EINVAL; 305311a7b371SAneesh Kumar K.V /* 305411a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 305511a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 305611a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 305711a7b371SAneesh Kumar K.V */ 305811a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 305911a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 306011a7b371SAneesh Kumar K.V return -ENOENT; 306111a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 306211a7b371SAneesh Kumar K.V } 3063c04030e1SUlrich Drepper 306411a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 306511a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 306611a7b371SAneesh Kumar K.V 306711a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 30681da177e4SLinus Torvalds if (error) 30692ad94ae6SAl Viro return error; 30702ad94ae6SAl Viro 3071dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 30721da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 30736902d925SDave Hansen if (IS_ERR(new_dentry)) 3074dae6ad8fSAl Viro goto out; 3075dae6ad8fSAl Viro 3076dae6ad8fSAl Viro error = -EXDEV; 3077dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3078dae6ad8fSAl Viro goto out_dput; 3079dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 308075c3f29dSDave Hansen if (error) 308175c3f29dSDave Hansen goto out_dput; 3082dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3083be6d3e56SKentaro Takeda if (error) 3084be6d3e56SKentaro Takeda goto out_drop_write; 3085dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 3086be6d3e56SKentaro Takeda out_drop_write: 3087dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 308875c3f29dSDave Hansen out_dput: 30891da177e4SLinus Torvalds dput(new_dentry); 3090dae6ad8fSAl Viro mutex_unlock(&new_path.dentry->d_inode->i_mutex); 3091dae6ad8fSAl Viro path_put(&new_path); 30921da177e4SLinus Torvalds out: 30932d8f3038SAl Viro path_put(&old_path); 30941da177e4SLinus Torvalds 30951da177e4SLinus Torvalds return error; 30961da177e4SLinus Torvalds } 30971da177e4SLinus Torvalds 30983480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 30995590ff0dSUlrich Drepper { 3100c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 31015590ff0dSUlrich Drepper } 31025590ff0dSUlrich Drepper 31031da177e4SLinus Torvalds /* 31041da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 31051da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 31061da177e4SLinus Torvalds * Problems: 31071da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 31081da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 31091da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3110a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 31111da177e4SLinus Torvalds * story. 31121da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 31131b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 31141da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 31151da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3116a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 31171da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 31181da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 31191da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3120a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 31211da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 31221da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 31231da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3124e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 31251b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 31261da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3127c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 31281da177e4SLinus Torvalds * locking]. 31291da177e4SLinus Torvalds */ 313075c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 31311da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31321da177e4SLinus Torvalds { 31331da177e4SLinus Torvalds int error = 0; 31349055cba7SSage Weil struct inode *target = new_dentry->d_inode; 31358de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 31361da177e4SLinus Torvalds 31371da177e4SLinus Torvalds /* 31381da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 31391da177e4SLinus Torvalds * we'll need to flip '..'. 31401da177e4SLinus Torvalds */ 31411da177e4SLinus Torvalds if (new_dir != old_dir) { 3142f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 31431da177e4SLinus Torvalds if (error) 31441da177e4SLinus Torvalds return error; 31451da177e4SLinus Torvalds } 31461da177e4SLinus Torvalds 31471da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 31481da177e4SLinus Torvalds if (error) 31491da177e4SLinus Torvalds return error; 31501da177e4SLinus Torvalds 31511d2ef590SAl Viro dget(new_dentry); 3152d83c49f3SAl Viro if (target) 31531b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 31549055cba7SSage Weil 31551da177e4SLinus Torvalds error = -EBUSY; 31569055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 31579055cba7SSage Weil goto out; 31589055cba7SSage Weil 31598de52778SAl Viro error = -EMLINK; 31608de52778SAl Viro if (max_links && !target && new_dir != old_dir && 31618de52778SAl Viro new_dir->i_nlink >= max_links) 31628de52778SAl Viro goto out; 31638de52778SAl Viro 31643cebde24SSage Weil if (target) 31653cebde24SSage Weil shrink_dcache_parent(new_dentry); 31661da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 31679055cba7SSage Weil if (error) 31689055cba7SSage Weil goto out; 31699055cba7SSage Weil 31701da177e4SLinus Torvalds if (target) { 31711da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3172d83c49f3SAl Viro dont_mount(new_dentry); 3173d83c49f3SAl Viro } 31749055cba7SSage Weil out: 31759055cba7SSage Weil if (target) 31761b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 31771d2ef590SAl Viro dput(new_dentry); 3178e31e14ecSStephen Smalley if (!error) 3179349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 31801da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 31811da177e4SLinus Torvalds return error; 31821da177e4SLinus Torvalds } 31831da177e4SLinus Torvalds 318475c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 31851da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 31861da177e4SLinus Torvalds { 318751892bbbSSage Weil struct inode *target = new_dentry->d_inode; 31881da177e4SLinus Torvalds int error; 31891da177e4SLinus Torvalds 31901da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 31911da177e4SLinus Torvalds if (error) 31921da177e4SLinus Torvalds return error; 31931da177e4SLinus Torvalds 31941da177e4SLinus Torvalds dget(new_dentry); 31951da177e4SLinus Torvalds if (target) 31961b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 319751892bbbSSage Weil 31981da177e4SLinus Torvalds error = -EBUSY; 319951892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 320051892bbbSSage Weil goto out; 320151892bbbSSage Weil 32021da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 320351892bbbSSage Weil if (error) 320451892bbbSSage Weil goto out; 320551892bbbSSage Weil 3206bec1052eSAl Viro if (target) 3207d83c49f3SAl Viro dont_mount(new_dentry); 3208349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 32091da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 321051892bbbSSage Weil out: 32111da177e4SLinus Torvalds if (target) 32121b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 32131da177e4SLinus Torvalds dput(new_dentry); 32141da177e4SLinus Torvalds return error; 32151da177e4SLinus Torvalds } 32161da177e4SLinus Torvalds 32171da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 32181da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 32191da177e4SLinus Torvalds { 32201da177e4SLinus Torvalds int error; 32211da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 322259b0df21SEric Paris const unsigned char *old_name; 32231da177e4SLinus Torvalds 32241da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 32251da177e4SLinus Torvalds return 0; 32261da177e4SLinus Torvalds 32271da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 32281da177e4SLinus Torvalds if (error) 32291da177e4SLinus Torvalds return error; 32301da177e4SLinus Torvalds 32311da177e4SLinus Torvalds if (!new_dentry->d_inode) 3232a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 32331da177e4SLinus Torvalds else 32341da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 32351da177e4SLinus Torvalds if (error) 32361da177e4SLinus Torvalds return error; 32371da177e4SLinus Torvalds 3238acfa4380SAl Viro if (!old_dir->i_op->rename) 32391da177e4SLinus Torvalds return -EPERM; 32401da177e4SLinus Torvalds 32410eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 32420eeca283SRobert Love 32431da177e4SLinus Torvalds if (is_dir) 32441da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 32451da177e4SLinus Torvalds else 32461da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3247123df294SAl Viro if (!error) 3248123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 32495a190ae6SAl Viro new_dentry->d_inode, old_dentry); 32500eeca283SRobert Love fsnotify_oldname_free(old_name); 32510eeca283SRobert Love 32521da177e4SLinus Torvalds return error; 32531da177e4SLinus Torvalds } 32541da177e4SLinus Torvalds 32552e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 32562e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 32571da177e4SLinus Torvalds { 32581da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 32591da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 32601da177e4SLinus Torvalds struct dentry *trap; 32611da177e4SLinus Torvalds struct nameidata oldnd, newnd; 32622ad94ae6SAl Viro char *from; 32632ad94ae6SAl Viro char *to; 32642ad94ae6SAl Viro int error; 32651da177e4SLinus Torvalds 32662ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 32671da177e4SLinus Torvalds if (error) 32681da177e4SLinus Torvalds goto exit; 32691da177e4SLinus Torvalds 32702ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 32711da177e4SLinus Torvalds if (error) 32721da177e4SLinus Torvalds goto exit1; 32731da177e4SLinus Torvalds 32741da177e4SLinus Torvalds error = -EXDEV; 32754ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 32761da177e4SLinus Torvalds goto exit2; 32771da177e4SLinus Torvalds 32784ac91378SJan Blunck old_dir = oldnd.path.dentry; 32791da177e4SLinus Torvalds error = -EBUSY; 32801da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 32811da177e4SLinus Torvalds goto exit2; 32821da177e4SLinus Torvalds 32834ac91378SJan Blunck new_dir = newnd.path.dentry; 32841da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 32851da177e4SLinus Torvalds goto exit2; 32861da177e4SLinus Torvalds 32870612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 32880612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 32894e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 32900612d9fbSOGAWA Hirofumi 32911da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 32921da177e4SLinus Torvalds 329349705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 32941da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 32951da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 32961da177e4SLinus Torvalds goto exit3; 32971da177e4SLinus Torvalds /* source must exist */ 32981da177e4SLinus Torvalds error = -ENOENT; 32991da177e4SLinus Torvalds if (!old_dentry->d_inode) 33001da177e4SLinus Torvalds goto exit4; 33011da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 33021da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 33031da177e4SLinus Torvalds error = -ENOTDIR; 33041da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 33051da177e4SLinus Torvalds goto exit4; 33061da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 33071da177e4SLinus Torvalds goto exit4; 33081da177e4SLinus Torvalds } 33091da177e4SLinus Torvalds /* source should not be ancestor of target */ 33101da177e4SLinus Torvalds error = -EINVAL; 33111da177e4SLinus Torvalds if (old_dentry == trap) 33121da177e4SLinus Torvalds goto exit4; 331349705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 33141da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 33151da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 33161da177e4SLinus Torvalds goto exit4; 33171da177e4SLinus Torvalds /* target should not be an ancestor of source */ 33181da177e4SLinus Torvalds error = -ENOTEMPTY; 33191da177e4SLinus Torvalds if (new_dentry == trap) 33201da177e4SLinus Torvalds goto exit5; 33211da177e4SLinus Torvalds 33229079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 33239079b1ebSDave Hansen if (error) 33249079b1ebSDave Hansen goto exit5; 3325be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3326be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3327be6d3e56SKentaro Takeda if (error) 3328be6d3e56SKentaro Takeda goto exit6; 33291da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 33301da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3331be6d3e56SKentaro Takeda exit6: 33329079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 33331da177e4SLinus Torvalds exit5: 33341da177e4SLinus Torvalds dput(new_dentry); 33351da177e4SLinus Torvalds exit4: 33361da177e4SLinus Torvalds dput(old_dentry); 33371da177e4SLinus Torvalds exit3: 33381da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 33391da177e4SLinus Torvalds exit2: 33401d957f9bSJan Blunck path_put(&newnd.path); 33412ad94ae6SAl Viro putname(to); 33421da177e4SLinus Torvalds exit1: 33431d957f9bSJan Blunck path_put(&oldnd.path); 33441da177e4SLinus Torvalds putname(from); 33452ad94ae6SAl Viro exit: 33461da177e4SLinus Torvalds return error; 33471da177e4SLinus Torvalds } 33481da177e4SLinus Torvalds 3349a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 33505590ff0dSUlrich Drepper { 33515590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 33525590ff0dSUlrich Drepper } 33535590ff0dSUlrich Drepper 33541da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 33551da177e4SLinus Torvalds { 33561da177e4SLinus Torvalds int len; 33571da177e4SLinus Torvalds 33581da177e4SLinus Torvalds len = PTR_ERR(link); 33591da177e4SLinus Torvalds if (IS_ERR(link)) 33601da177e4SLinus Torvalds goto out; 33611da177e4SLinus Torvalds 33621da177e4SLinus Torvalds len = strlen(link); 33631da177e4SLinus Torvalds if (len > (unsigned) buflen) 33641da177e4SLinus Torvalds len = buflen; 33651da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 33661da177e4SLinus Torvalds len = -EFAULT; 33671da177e4SLinus Torvalds out: 33681da177e4SLinus Torvalds return len; 33691da177e4SLinus Torvalds } 33701da177e4SLinus Torvalds 33711da177e4SLinus Torvalds /* 33721da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 33731da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 33741da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 33751da177e4SLinus Torvalds */ 33761da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 33771da177e4SLinus Torvalds { 33781da177e4SLinus Torvalds struct nameidata nd; 3379cc314eefSLinus Torvalds void *cookie; 3380694a1764SMarcin Slusarz int res; 3381cc314eefSLinus Torvalds 33821da177e4SLinus Torvalds nd.depth = 0; 3383cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3384694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3385694a1764SMarcin Slusarz return PTR_ERR(cookie); 3386694a1764SMarcin Slusarz 3387694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 33881da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3389cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3390694a1764SMarcin Slusarz return res; 33911da177e4SLinus Torvalds } 33921da177e4SLinus Torvalds 33931da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 33941da177e4SLinus Torvalds { 33951da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 33961da177e4SLinus Torvalds } 33971da177e4SLinus Torvalds 33981da177e4SLinus Torvalds /* get the link contents into pagecache */ 33991da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 34001da177e4SLinus Torvalds { 3401ebd09abbSDuane Griffin char *kaddr; 34021da177e4SLinus Torvalds struct page *page; 34031da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3404090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 34051da177e4SLinus Torvalds if (IS_ERR(page)) 34066fe6900eSNick Piggin return (char*)page; 34071da177e4SLinus Torvalds *ppage = page; 3408ebd09abbSDuane Griffin kaddr = kmap(page); 3409ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3410ebd09abbSDuane Griffin return kaddr; 34111da177e4SLinus Torvalds } 34121da177e4SLinus Torvalds 34131da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 34141da177e4SLinus Torvalds { 34151da177e4SLinus Torvalds struct page *page = NULL; 34161da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 34171da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 34181da177e4SLinus Torvalds if (page) { 34191da177e4SLinus Torvalds kunmap(page); 34201da177e4SLinus Torvalds page_cache_release(page); 34211da177e4SLinus Torvalds } 34221da177e4SLinus Torvalds return res; 34231da177e4SLinus Torvalds } 34241da177e4SLinus Torvalds 3425cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 34261da177e4SLinus Torvalds { 3427cc314eefSLinus Torvalds struct page *page = NULL; 34281da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3429cc314eefSLinus Torvalds return page; 34301da177e4SLinus Torvalds } 34311da177e4SLinus Torvalds 3432cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 34331da177e4SLinus Torvalds { 3434cc314eefSLinus Torvalds struct page *page = cookie; 3435cc314eefSLinus Torvalds 3436cc314eefSLinus Torvalds if (page) { 34371da177e4SLinus Torvalds kunmap(page); 34381da177e4SLinus Torvalds page_cache_release(page); 34391da177e4SLinus Torvalds } 34401da177e4SLinus Torvalds } 34411da177e4SLinus Torvalds 344254566b2cSNick Piggin /* 344354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 344454566b2cSNick Piggin */ 344554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 34461da177e4SLinus Torvalds { 34471da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 34480adb25d2SKirill Korotaev struct page *page; 3449afddba49SNick Piggin void *fsdata; 3450beb497abSDmitriy Monakhov int err; 34511da177e4SLinus Torvalds char *kaddr; 345254566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 345354566b2cSNick Piggin if (nofs) 345454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 34551da177e4SLinus Torvalds 34567e53cac4SNeilBrown retry: 3457afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 345854566b2cSNick Piggin flags, &page, &fsdata); 34591da177e4SLinus Torvalds if (err) 3460afddba49SNick Piggin goto fail; 3461afddba49SNick Piggin 3462e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 34631da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 3464e8e3c3d6SCong Wang kunmap_atomic(kaddr); 3465afddba49SNick Piggin 3466afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3467afddba49SNick Piggin page, fsdata); 34681da177e4SLinus Torvalds if (err < 0) 34691da177e4SLinus Torvalds goto fail; 3470afddba49SNick Piggin if (err < len-1) 3471afddba49SNick Piggin goto retry; 3472afddba49SNick Piggin 34731da177e4SLinus Torvalds mark_inode_dirty(inode); 34741da177e4SLinus Torvalds return 0; 34751da177e4SLinus Torvalds fail: 34761da177e4SLinus Torvalds return err; 34771da177e4SLinus Torvalds } 34781da177e4SLinus Torvalds 34790adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 34800adb25d2SKirill Korotaev { 34810adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 348254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 34830adb25d2SKirill Korotaev } 34840adb25d2SKirill Korotaev 348592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 34861da177e4SLinus Torvalds .readlink = generic_readlink, 34871da177e4SLinus Torvalds .follow_link = page_follow_link_light, 34881da177e4SLinus Torvalds .put_link = page_put_link, 34891da177e4SLinus Torvalds }; 34901da177e4SLinus Torvalds 34912d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3492cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 34931da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 34941da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 34951da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 34961da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 34971da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 34981da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 34991da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 35001da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 35011da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 35020adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 35031da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 35041da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3505d1811465SAl Viro EXPORT_SYMBOL(kern_path); 350616f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3507f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 35081da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 35091da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 35101da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 35111da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 35121da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 35131da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 35141da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 35151da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 35161da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 35171da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 35181da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 35191da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 35201da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 35211da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3522