11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 181da177e4SLinus Torvalds #include <linux/module.h> 191da177e4SLinus Torvalds #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/namei.h> 221da177e4SLinus Torvalds #include <linux/pagemap.h> 230eeca283SRobert Love #include <linux/fsnotify.h> 241da177e4SLinus Torvalds #include <linux/personality.h> 251da177e4SLinus Torvalds #include <linux/security.h> 266146f0d5SMimi Zohar #include <linux/ima.h> 271da177e4SLinus Torvalds #include <linux/syscalls.h> 281da177e4SLinus Torvalds #include <linux/mount.h> 291da177e4SLinus Torvalds #include <linux/audit.h> 3016f7e0feSRandy Dunlap #include <linux/capability.h> 31834f2a4aSTrond Myklebust #include <linux/file.h> 325590ff0dSUlrich Drepper #include <linux/fcntl.h> 3308ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 345ad4e53bSAl Viro #include <linux/fs_struct.h> 35e77819e5SLinus Torvalds #include <linux/posix_acl.h> 361da177e4SLinus Torvalds #include <asm/uaccess.h> 371da177e4SLinus Torvalds 38e81e3f4dSEric Paris #include "internal.h" 39e81e3f4dSEric Paris 401da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 411da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 421da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 431da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 441da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 451da177e4SLinus Torvalds * 461da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 471da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 481da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 491da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 501da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 511da177e4SLinus Torvalds * the special cases of the former code. 521da177e4SLinus Torvalds * 531da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 541da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 551da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 561da177e4SLinus Torvalds * 571da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 581da177e4SLinus Torvalds * resolution to correspond with current state of the code. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 611da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 621da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 631da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 641da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 651da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 661da177e4SLinus Torvalds */ 671da177e4SLinus Torvalds 681da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 691da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 701da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 711da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 721da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 731da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7425985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 751da177e4SLinus Torvalds * 761da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 771da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 781da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 791da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 801da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 811da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 821da177e4SLinus Torvalds * and in the old Linux semantics. 831da177e4SLinus Torvalds */ 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 861da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 871da177e4SLinus Torvalds * 881da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 921da177e4SLinus Torvalds * inside the path - always follow. 931da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 941da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 951da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 961da177e4SLinus Torvalds * otherwise - don't follow. 971da177e4SLinus Torvalds * (applied in that order). 981da177e4SLinus Torvalds * 991da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1001da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1011da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1021da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1031da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1041da177e4SLinus Torvalds */ 1051da177e4SLinus Torvalds /* 1061da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 107a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1081da177e4SLinus Torvalds * any extra contention... 1091da177e4SLinus Torvalds */ 1101da177e4SLinus Torvalds 1111da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1121da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1131da177e4SLinus Torvalds * kernel data space before using them.. 1141da177e4SLinus Torvalds * 1151da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1161da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1171da177e4SLinus Torvalds */ 118858119e1SArjan van de Ven static int do_getname(const char __user *filename, char *page) 1191da177e4SLinus Torvalds { 1201da177e4SLinus Torvalds int retval; 1211da177e4SLinus Torvalds unsigned long len = PATH_MAX; 1221da177e4SLinus Torvalds 1231da177e4SLinus Torvalds if (!segment_eq(get_fs(), KERNEL_DS)) { 1241da177e4SLinus Torvalds if ((unsigned long) filename >= TASK_SIZE) 1251da177e4SLinus Torvalds return -EFAULT; 1261da177e4SLinus Torvalds if (TASK_SIZE - (unsigned long) filename < PATH_MAX) 1271da177e4SLinus Torvalds len = TASK_SIZE - (unsigned long) filename; 1281da177e4SLinus Torvalds } 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds retval = strncpy_from_user(page, filename, len); 1311da177e4SLinus Torvalds if (retval > 0) { 1321da177e4SLinus Torvalds if (retval < len) 1331da177e4SLinus Torvalds return 0; 1341da177e4SLinus Torvalds return -ENAMETOOLONG; 1351da177e4SLinus Torvalds } else if (!retval) 1361da177e4SLinus Torvalds retval = -ENOENT; 1371da177e4SLinus Torvalds return retval; 1381da177e4SLinus Torvalds } 1391da177e4SLinus Torvalds 140f52e0c11SAl Viro static char *getname_flags(const char __user * filename, int flags) 1411da177e4SLinus Torvalds { 1421da177e4SLinus Torvalds char *tmp, *result; 1431da177e4SLinus Torvalds 1441da177e4SLinus Torvalds result = ERR_PTR(-ENOMEM); 1451da177e4SLinus Torvalds tmp = __getname(); 1461da177e4SLinus Torvalds if (tmp) { 1471da177e4SLinus Torvalds int retval = do_getname(filename, tmp); 1481da177e4SLinus Torvalds 1491da177e4SLinus Torvalds result = tmp; 1501da177e4SLinus Torvalds if (retval < 0) { 151f52e0c11SAl Viro if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { 1521da177e4SLinus Torvalds __putname(tmp); 1531da177e4SLinus Torvalds result = ERR_PTR(retval); 1541da177e4SLinus Torvalds } 1551da177e4SLinus Torvalds } 156f52e0c11SAl Viro } 1571da177e4SLinus Torvalds audit_getname(result); 1581da177e4SLinus Torvalds return result; 1591da177e4SLinus Torvalds } 1601da177e4SLinus Torvalds 161f52e0c11SAl Viro char *getname(const char __user * filename) 162f52e0c11SAl Viro { 163f52e0c11SAl Viro return getname_flags(filename, 0); 164f52e0c11SAl Viro } 165f52e0c11SAl Viro 1661da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 1671da177e4SLinus Torvalds void putname(const char *name) 1681da177e4SLinus Torvalds { 1695ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 1701da177e4SLinus Torvalds audit_putname(name); 1711da177e4SLinus Torvalds else 1721da177e4SLinus Torvalds __putname(name); 1731da177e4SLinus Torvalds } 1741da177e4SLinus Torvalds EXPORT_SYMBOL(putname); 1751da177e4SLinus Torvalds #endif 1761da177e4SLinus Torvalds 177e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 178e77819e5SLinus Torvalds { 17984635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 180e77819e5SLinus Torvalds struct posix_acl *acl; 181e77819e5SLinus Torvalds 182e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 1833567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 1843567866bSAl Viro if (!acl) 185e77819e5SLinus Torvalds return -EAGAIN; 1863567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 1873567866bSAl Viro if (acl == ACL_NOT_CACHED) 188e77819e5SLinus Torvalds return -ECHILD; 189206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 190e77819e5SLinus Torvalds } 191e77819e5SLinus Torvalds 192e77819e5SLinus Torvalds acl = get_cached_acl(inode, ACL_TYPE_ACCESS); 193e77819e5SLinus Torvalds 194e77819e5SLinus Torvalds /* 1954e34e719SChristoph Hellwig * A filesystem can force a ACL callback by just never filling the 1964e34e719SChristoph Hellwig * ACL cache. But normally you'd fill the cache either at inode 1974e34e719SChristoph Hellwig * instantiation time, or on the first ->get_acl call. 198e77819e5SLinus Torvalds * 1994e34e719SChristoph Hellwig * If the filesystem doesn't have a get_acl() function at all, we'll 2004e34e719SChristoph Hellwig * just create the negative cache entry. 201e77819e5SLinus Torvalds */ 202e77819e5SLinus Torvalds if (acl == ACL_NOT_CACHED) { 2034e34e719SChristoph Hellwig if (inode->i_op->get_acl) { 2044e34e719SChristoph Hellwig acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); 2054e34e719SChristoph Hellwig if (IS_ERR(acl)) 2064e34e719SChristoph Hellwig return PTR_ERR(acl); 2074e34e719SChristoph Hellwig } else { 208e77819e5SLinus Torvalds set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); 209e77819e5SLinus Torvalds return -EAGAIN; 210e77819e5SLinus Torvalds } 2114e34e719SChristoph Hellwig } 212e77819e5SLinus Torvalds 213e77819e5SLinus Torvalds if (acl) { 214e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 215e77819e5SLinus Torvalds posix_acl_release(acl); 216e77819e5SLinus Torvalds return error; 217e77819e5SLinus Torvalds } 21884635d68SLinus Torvalds #endif 219e77819e5SLinus Torvalds 220e77819e5SLinus Torvalds return -EAGAIN; 221e77819e5SLinus Torvalds } 222e77819e5SLinus Torvalds 2235909ccaaSLinus Torvalds /* 224948409c7SAndreas Gruenbacher * This does the basic permission checking 2255909ccaaSLinus Torvalds */ 2267e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2275909ccaaSLinus Torvalds { 22826cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2295909ccaaSLinus Torvalds 230e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 231e795b717SSerge E. Hallyn goto other_perms; 232e795b717SSerge E. Hallyn 23314067ff5SLinus Torvalds if (likely(current_fsuid() == inode->i_uid)) 2345909ccaaSLinus Torvalds mode >>= 6; 2355909ccaaSLinus Torvalds else { 236e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2377e40145eSAl Viro int error = check_acl(inode, mask); 2385909ccaaSLinus Torvalds if (error != -EAGAIN) 2395909ccaaSLinus Torvalds return error; 2405909ccaaSLinus Torvalds } 2415909ccaaSLinus Torvalds 2425909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2435909ccaaSLinus Torvalds mode >>= 3; 2445909ccaaSLinus Torvalds } 2455909ccaaSLinus Torvalds 246e795b717SSerge E. Hallyn other_perms: 2475909ccaaSLinus Torvalds /* 2485909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2495909ccaaSLinus Torvalds */ 2509c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2515909ccaaSLinus Torvalds return 0; 2525909ccaaSLinus Torvalds return -EACCES; 2535909ccaaSLinus Torvalds } 2541da177e4SLinus Torvalds 2551da177e4SLinus Torvalds /** 2561da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2571da177e4SLinus Torvalds * @inode: inode to check access rights for 2588fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 2591da177e4SLinus Torvalds * 2601da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 2611da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 2621da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 263b74c79e9SNick Piggin * are used for other things. 264b74c79e9SNick Piggin * 265b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 266b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 267b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 2681da177e4SLinus Torvalds */ 2692830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 2701da177e4SLinus Torvalds { 2715909ccaaSLinus Torvalds int ret; 2721da177e4SLinus Torvalds 2731da177e4SLinus Torvalds /* 274948409c7SAndreas Gruenbacher * Do the basic permission checks. 2751da177e4SLinus Torvalds */ 2767e40145eSAl Viro ret = acl_permission_check(inode, mask); 2775909ccaaSLinus Torvalds if (ret != -EACCES) 2785909ccaaSLinus Torvalds return ret; 2791da177e4SLinus Torvalds 280d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 281d594e7ecSAl Viro /* DACs are overridable for directories */ 282d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 283d594e7ecSAl Viro return 0; 284d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 285d594e7ecSAl Viro if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 286d594e7ecSAl Viro return 0; 287d594e7ecSAl Viro return -EACCES; 288d594e7ecSAl Viro } 2891da177e4SLinus Torvalds /* 2901da177e4SLinus Torvalds * Read/write DACs are always overridable. 291d594e7ecSAl Viro * Executable DACs are overridable when there is 292d594e7ecSAl Viro * at least one exec bit set. 2931da177e4SLinus Torvalds */ 294d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 295e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) 2961da177e4SLinus Torvalds return 0; 2971da177e4SLinus Torvalds 2981da177e4SLinus Torvalds /* 2991da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3001da177e4SLinus Torvalds */ 3017ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 302d594e7ecSAl Viro if (mask == MAY_READ) 303e795b717SSerge E. Hallyn if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) 3041da177e4SLinus Torvalds return 0; 3051da177e4SLinus Torvalds 3061da177e4SLinus Torvalds return -EACCES; 3071da177e4SLinus Torvalds } 3081da177e4SLinus Torvalds 3093ddcd056SLinus Torvalds /* 3103ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3113ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3123ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3133ddcd056SLinus Torvalds * permission function, use the fast case". 3143ddcd056SLinus Torvalds */ 3153ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3163ddcd056SLinus Torvalds { 3173ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3183ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3193ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3203ddcd056SLinus Torvalds 3213ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3223ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3233ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3243ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3253ddcd056SLinus Torvalds } 3263ddcd056SLinus Torvalds return generic_permission(inode, mask); 3273ddcd056SLinus Torvalds } 3283ddcd056SLinus Torvalds 329cb23beb5SChristoph Hellwig /** 330cb23beb5SChristoph Hellwig * inode_permission - check for access rights to a given inode 331cb23beb5SChristoph Hellwig * @inode: inode to check permission on 3328fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 333cb23beb5SChristoph Hellwig * 334cb23beb5SChristoph Hellwig * Used to check for read/write/execute permissions on an inode. 335cb23beb5SChristoph Hellwig * We use "fsuid" for this, letting us set arbitrary permissions 336cb23beb5SChristoph Hellwig * for filesystem access without changing the "normal" uids which 337cb23beb5SChristoph Hellwig * are used for other things. 338948409c7SAndreas Gruenbacher * 339948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 340cb23beb5SChristoph Hellwig */ 341f419a2e3SAl Viro int inode_permission(struct inode *inode, int mask) 3421da177e4SLinus Torvalds { 343e6305c43SAl Viro int retval; 3441da177e4SLinus Torvalds 3453ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 34622590e41SMiklos Szeredi umode_t mode = inode->i_mode; 3471da177e4SLinus Torvalds 3481da177e4SLinus Torvalds /* 3491da177e4SLinus Torvalds * Nobody gets write access to a read-only fs. 3501da177e4SLinus Torvalds */ 3511da177e4SLinus Torvalds if (IS_RDONLY(inode) && 3521da177e4SLinus Torvalds (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 3531da177e4SLinus Torvalds return -EROFS; 3541da177e4SLinus Torvalds 3551da177e4SLinus Torvalds /* 3561da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3571da177e4SLinus Torvalds */ 3581da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3591da177e4SLinus Torvalds return -EACCES; 3601da177e4SLinus Torvalds } 3611da177e4SLinus Torvalds 3623ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3631da177e4SLinus Torvalds if (retval) 3641da177e4SLinus Torvalds return retval; 3651da177e4SLinus Torvalds 36608ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 36708ce5f16SSerge E. Hallyn if (retval) 36808ce5f16SSerge E. Hallyn return retval; 36908ce5f16SSerge E. Hallyn 370d09ca739SEric Paris return security_inode_permission(inode, mask); 3711da177e4SLinus Torvalds } 3721da177e4SLinus Torvalds 373f4d6ff89SAl Viro /** 3745dd784d0SJan Blunck * path_get - get a reference to a path 3755dd784d0SJan Blunck * @path: path to get the reference to 3765dd784d0SJan Blunck * 3775dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 3785dd784d0SJan Blunck */ 3795dd784d0SJan Blunck void path_get(struct path *path) 3805dd784d0SJan Blunck { 3815dd784d0SJan Blunck mntget(path->mnt); 3825dd784d0SJan Blunck dget(path->dentry); 3835dd784d0SJan Blunck } 3845dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 3855dd784d0SJan Blunck 3865dd784d0SJan Blunck /** 3871d957f9bSJan Blunck * path_put - put a reference to a path 3881d957f9bSJan Blunck * @path: path to put the reference to 3891d957f9bSJan Blunck * 3901d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 3911d957f9bSJan Blunck */ 3921d957f9bSJan Blunck void path_put(struct path *path) 3931da177e4SLinus Torvalds { 3941d957f9bSJan Blunck dput(path->dentry); 3951d957f9bSJan Blunck mntput(path->mnt); 3961da177e4SLinus Torvalds } 3971d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 3981da177e4SLinus Torvalds 39919660af7SAl Viro /* 40031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 40119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 40219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 40319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 40419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 40519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 40619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 40719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 40831e6b01fSNick Piggin */ 40931e6b01fSNick Piggin 41031e6b01fSNick Piggin /** 41119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 41219660af7SAl Viro * @nd: nameidata pathwalk data 41319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 41439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 41531e6b01fSNick Piggin * 41619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 41719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 41819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 41931e6b01fSNick Piggin */ 42019660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 42131e6b01fSNick Piggin { 42231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 42331e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 4245b6ca027SAl Viro int want_root = 0; 42531e6b01fSNick Piggin 42631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 4275b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 4285b6ca027SAl Viro want_root = 1; 42931e6b01fSNick Piggin spin_lock(&fs->lock); 43031e6b01fSNick Piggin if (nd->root.mnt != fs->root.mnt || 43131e6b01fSNick Piggin nd->root.dentry != fs->root.dentry) 43231e6b01fSNick Piggin goto err_root; 43331e6b01fSNick Piggin } 43431e6b01fSNick Piggin spin_lock(&parent->d_lock); 43519660af7SAl Viro if (!dentry) { 43619660af7SAl Viro if (!__d_rcu_to_refcount(parent, nd->seq)) 43719660af7SAl Viro goto err_parent; 43819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 43919660af7SAl Viro } else { 44094c0d4ecSAl Viro if (dentry->d_parent != parent) 44194c0d4ecSAl Viro goto err_parent; 44231e6b01fSNick Piggin spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); 44331e6b01fSNick Piggin if (!__d_rcu_to_refcount(dentry, nd->seq)) 44419660af7SAl Viro goto err_child; 44531e6b01fSNick Piggin /* 44619660af7SAl Viro * If the sequence check on the child dentry passed, then 44719660af7SAl Viro * the child has not been removed from its parent. This 44819660af7SAl Viro * means the parent dentry must be valid and able to take 44919660af7SAl Viro * a reference at this point. 45031e6b01fSNick Piggin */ 45131e6b01fSNick Piggin BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); 45231e6b01fSNick Piggin BUG_ON(!parent->d_count); 45331e6b01fSNick Piggin parent->d_count++; 45431e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 45519660af7SAl Viro } 45631e6b01fSNick Piggin spin_unlock(&parent->d_lock); 4575b6ca027SAl Viro if (want_root) { 45831e6b01fSNick Piggin path_get(&nd->root); 45931e6b01fSNick Piggin spin_unlock(&fs->lock); 46031e6b01fSNick Piggin } 46131e6b01fSNick Piggin mntget(nd->path.mnt); 46231e6b01fSNick Piggin 46331e6b01fSNick Piggin rcu_read_unlock(); 46431e6b01fSNick Piggin br_read_unlock(vfsmount_lock); 46531e6b01fSNick Piggin nd->flags &= ~LOOKUP_RCU; 46631e6b01fSNick Piggin return 0; 46719660af7SAl Viro 46819660af7SAl Viro err_child: 46931e6b01fSNick Piggin spin_unlock(&dentry->d_lock); 47019660af7SAl Viro err_parent: 47131e6b01fSNick Piggin spin_unlock(&parent->d_lock); 47231e6b01fSNick Piggin err_root: 4735b6ca027SAl Viro if (want_root) 47431e6b01fSNick Piggin spin_unlock(&fs->lock); 47531e6b01fSNick Piggin return -ECHILD; 47631e6b01fSNick Piggin } 47731e6b01fSNick Piggin 47831e6b01fSNick Piggin /** 479834f2a4aSTrond Myklebust * release_open_intent - free up open intent resources 480834f2a4aSTrond Myklebust * @nd: pointer to nameidata 481834f2a4aSTrond Myklebust */ 482834f2a4aSTrond Myklebust void release_open_intent(struct nameidata *nd) 483834f2a4aSTrond Myklebust { 4842dab5974SLinus Torvalds struct file *file = nd->intent.open.file; 4852dab5974SLinus Torvalds 4862dab5974SLinus Torvalds if (file && !IS_ERR(file)) { 4872dab5974SLinus Torvalds if (file->f_path.dentry == NULL) 4882dab5974SLinus Torvalds put_filp(file); 489834f2a4aSTrond Myklebust else 4902dab5974SLinus Torvalds fput(file); 4912dab5974SLinus Torvalds } 492834f2a4aSTrond Myklebust } 493834f2a4aSTrond Myklebust 494f60aef7eSAl Viro static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) 49534286d66SNick Piggin { 496f60aef7eSAl Viro return dentry->d_op->d_revalidate(dentry, nd); 49734286d66SNick Piggin } 49834286d66SNick Piggin 4999f1fafeeSAl Viro /** 5009f1fafeeSAl Viro * complete_walk - successful completion of path walk 5019f1fafeeSAl Viro * @nd: pointer nameidata 50239159de2SJeff Layton * 5039f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5049f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5059f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5069f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5079f1fafeeSAl Viro * need to drop nd->path. 50839159de2SJeff Layton */ 5099f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 51039159de2SJeff Layton { 51116c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 51239159de2SJeff Layton int status; 51339159de2SJeff Layton 5149f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 5159f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 5169f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 5179f1fafeeSAl Viro nd->root.mnt = NULL; 5189f1fafeeSAl Viro spin_lock(&dentry->d_lock); 5199f1fafeeSAl Viro if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { 5209f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5219f1fafeeSAl Viro rcu_read_unlock(); 5229f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5239f1fafeeSAl Viro return -ECHILD; 5249f1fafeeSAl Viro } 5259f1fafeeSAl Viro BUG_ON(nd->inode != dentry->d_inode); 5269f1fafeeSAl Viro spin_unlock(&dentry->d_lock); 5279f1fafeeSAl Viro mntget(nd->path.mnt); 5289f1fafeeSAl Viro rcu_read_unlock(); 5299f1fafeeSAl Viro br_read_unlock(vfsmount_lock); 5309f1fafeeSAl Viro } 5319f1fafeeSAl Viro 53216c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 53339159de2SJeff Layton return 0; 53439159de2SJeff Layton 53516c2cd71SAl Viro if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) 53616c2cd71SAl Viro return 0; 53716c2cd71SAl Viro 53816c2cd71SAl Viro if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) 53916c2cd71SAl Viro return 0; 54016c2cd71SAl Viro 54116c2cd71SAl Viro /* Note: we do not d_invalidate() */ 54234286d66SNick Piggin status = d_revalidate(dentry, nd); 54339159de2SJeff Layton if (status > 0) 54439159de2SJeff Layton return 0; 54539159de2SJeff Layton 54616c2cd71SAl Viro if (!status) 54739159de2SJeff Layton status = -ESTALE; 54816c2cd71SAl Viro 5499f1fafeeSAl Viro path_put(&nd->path); 55039159de2SJeff Layton return status; 55139159de2SJeff Layton } 55239159de2SJeff Layton 5532a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 5542a737871SAl Viro { 555f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 556f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 5572a737871SAl Viro } 5582a737871SAl Viro 5596de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 5606de88d72SAl Viro 56131e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 56231e6b01fSNick Piggin { 56331e6b01fSNick Piggin if (!nd->root.mnt) { 56431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 565c28cc364SNick Piggin unsigned seq; 566c28cc364SNick Piggin 567c28cc364SNick Piggin do { 568c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 56931e6b01fSNick Piggin nd->root = fs->root; 570c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 571c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 57231e6b01fSNick Piggin } 57331e6b01fSNick Piggin } 57431e6b01fSNick Piggin 575f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 5761da177e4SLinus Torvalds { 57731e6b01fSNick Piggin int ret; 57831e6b01fSNick Piggin 5791da177e4SLinus Torvalds if (IS_ERR(link)) 5801da177e4SLinus Torvalds goto fail; 5811da177e4SLinus Torvalds 5821da177e4SLinus Torvalds if (*link == '/') { 5832a737871SAl Viro set_root(nd); 5841d957f9bSJan Blunck path_put(&nd->path); 5852a737871SAl Viro nd->path = nd->root; 5862a737871SAl Viro path_get(&nd->root); 58716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 5881da177e4SLinus Torvalds } 58931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 590b4091d5fSChristoph Hellwig 59131e6b01fSNick Piggin ret = link_path_walk(link, nd); 59231e6b01fSNick Piggin return ret; 5931da177e4SLinus Torvalds fail: 5941d957f9bSJan Blunck path_put(&nd->path); 5951da177e4SLinus Torvalds return PTR_ERR(link); 5961da177e4SLinus Torvalds } 5971da177e4SLinus Torvalds 5981d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 599051d3812SIan Kent { 600051d3812SIan Kent dput(path->dentry); 6014ac91378SJan Blunck if (path->mnt != nd->path.mnt) 602051d3812SIan Kent mntput(path->mnt); 603051d3812SIan Kent } 604051d3812SIan Kent 6057b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6067b9337aaSNick Piggin struct nameidata *nd) 607051d3812SIan Kent { 60831e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6094ac91378SJan Blunck dput(nd->path.dentry); 61031e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6114ac91378SJan Blunck mntput(nd->path.mnt); 6129a229683SHuang Shijie } 61331e6b01fSNick Piggin nd->path.mnt = path->mnt; 6144ac91378SJan Blunck nd->path.dentry = path->dentry; 615051d3812SIan Kent } 616051d3812SIan Kent 617574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 618574197e0SAl Viro { 619574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 620574197e0SAl Viro if (!IS_ERR(cookie) && inode->i_op->put_link) 621574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 622574197e0SAl Viro path_put(link); 623574197e0SAl Viro } 624574197e0SAl Viro 625def4af30SAl Viro static __always_inline int 626574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 6271da177e4SLinus Torvalds { 6281da177e4SLinus Torvalds int error; 6297b9337aaSNick Piggin struct dentry *dentry = link->dentry; 6301da177e4SLinus Torvalds 631844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 632844a3917SAl Viro 6330e794589SAl Viro if (link->mnt == nd->path.mnt) 6340e794589SAl Viro mntget(link->mnt); 6350e794589SAl Viro 636574197e0SAl Viro if (unlikely(current->total_link_count >= 40)) { 637574197e0SAl Viro *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ 638574197e0SAl Viro path_put(&nd->path); 639574197e0SAl Viro return -ELOOP; 640574197e0SAl Viro } 641574197e0SAl Viro cond_resched(); 642574197e0SAl Viro current->total_link_count++; 643574197e0SAl Viro 6447b9337aaSNick Piggin touch_atime(link->mnt, dentry); 6451da177e4SLinus Torvalds nd_set_link(nd, NULL); 646cd4e91d3SAl Viro 64736f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 64836f3b4f6SAl Viro if (error) { 64936f3b4f6SAl Viro *p = ERR_PTR(error); /* no ->put_link(), please */ 65036f3b4f6SAl Viro path_put(&nd->path); 65136f3b4f6SAl Viro return error; 65236f3b4f6SAl Viro } 65336f3b4f6SAl Viro 65486acdca1SAl Viro nd->last_type = LAST_BIND; 655def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 656def4af30SAl Viro error = PTR_ERR(*p); 657def4af30SAl Viro if (!IS_ERR(*p)) { 6581da177e4SLinus Torvalds char *s = nd_get_link(nd); 659cc314eefSLinus Torvalds error = 0; 6601da177e4SLinus Torvalds if (s) 6611da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 662bcda7652SAl Viro else if (nd->last_type == LAST_BIND) { 66316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 664b21041d0SAl Viro nd->inode = nd->path.dentry->d_inode; 665b21041d0SAl Viro if (nd->inode->i_op->follow_link) { 666bcda7652SAl Viro /* stepped on a _really_ weird one */ 667bcda7652SAl Viro path_put(&nd->path); 668bcda7652SAl Viro error = -ELOOP; 669bcda7652SAl Viro } 670bcda7652SAl Viro } 6711da177e4SLinus Torvalds } 6721da177e4SLinus Torvalds return error; 6731da177e4SLinus Torvalds } 6741da177e4SLinus Torvalds 67531e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 67631e6b01fSNick Piggin { 67731e6b01fSNick Piggin struct vfsmount *parent; 67831e6b01fSNick Piggin struct dentry *mountpoint; 67931e6b01fSNick Piggin 68031e6b01fSNick Piggin parent = path->mnt->mnt_parent; 68131e6b01fSNick Piggin if (parent == path->mnt) 68231e6b01fSNick Piggin return 0; 68331e6b01fSNick Piggin mountpoint = path->mnt->mnt_mountpoint; 68431e6b01fSNick Piggin path->dentry = mountpoint; 68531e6b01fSNick Piggin path->mnt = parent; 68631e6b01fSNick Piggin return 1; 68731e6b01fSNick Piggin } 68831e6b01fSNick Piggin 689bab77ebfSAl Viro int follow_up(struct path *path) 6901da177e4SLinus Torvalds { 6911da177e4SLinus Torvalds struct vfsmount *parent; 6921da177e4SLinus Torvalds struct dentry *mountpoint; 69399b7db7bSNick Piggin 69499b7db7bSNick Piggin br_read_lock(vfsmount_lock); 695bab77ebfSAl Viro parent = path->mnt->mnt_parent; 696bab77ebfSAl Viro if (parent == path->mnt) { 69799b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 6981da177e4SLinus Torvalds return 0; 6991da177e4SLinus Torvalds } 7001da177e4SLinus Torvalds mntget(parent); 701bab77ebfSAl Viro mountpoint = dget(path->mnt->mnt_mountpoint); 70299b7db7bSNick Piggin br_read_unlock(vfsmount_lock); 703bab77ebfSAl Viro dput(path->dentry); 704bab77ebfSAl Viro path->dentry = mountpoint; 705bab77ebfSAl Viro mntput(path->mnt); 706bab77ebfSAl Viro path->mnt = parent; 7071da177e4SLinus Torvalds return 1; 7081da177e4SLinus Torvalds } 7091da177e4SLinus Torvalds 710b5c84bf6SNick Piggin /* 7119875cf80SDavid Howells * Perform an automount 7129875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 7139875cf80SDavid Howells * were called with. 7141da177e4SLinus Torvalds */ 7159875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 7169875cf80SDavid Howells bool *need_mntput) 71731e6b01fSNick Piggin { 7189875cf80SDavid Howells struct vfsmount *mnt; 719ea5b778aSDavid Howells int err; 7209875cf80SDavid Howells 7219875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 7229875cf80SDavid Howells return -EREMOTE; 7239875cf80SDavid Howells 7240ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 7250ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 7260ec26fd0SMiklos Szeredi * the name. 7270ec26fd0SMiklos Szeredi * 7280ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 7295a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 7300ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 7310ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 7320ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 7330ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 7345a30d8a2SDavid Howells */ 7355a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 736d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 7375a30d8a2SDavid Howells path->dentry->d_inode) 7389875cf80SDavid Howells return -EISDIR; 7390ec26fd0SMiklos Szeredi 7409875cf80SDavid Howells current->total_link_count++; 7419875cf80SDavid Howells if (current->total_link_count >= 40) 7429875cf80SDavid Howells return -ELOOP; 7439875cf80SDavid Howells 7449875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 7459875cf80SDavid Howells if (IS_ERR(mnt)) { 7469875cf80SDavid Howells /* 7479875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 7489875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 7499875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 7509875cf80SDavid Howells * 7519875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 7529875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 7539875cf80SDavid Howells * the path is inaccessible and we should say so. 7549875cf80SDavid Howells */ 75549084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 7569875cf80SDavid Howells return -EREMOTE; 7579875cf80SDavid Howells return PTR_ERR(mnt); 75831e6b01fSNick Piggin } 759ea5b778aSDavid Howells 7609875cf80SDavid Howells if (!mnt) /* mount collision */ 7619875cf80SDavid Howells return 0; 7629875cf80SDavid Howells 7638aef1884SAl Viro if (!*need_mntput) { 7648aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 7658aef1884SAl Viro mntget(path->mnt); 7668aef1884SAl Viro *need_mntput = true; 7678aef1884SAl Viro } 76819a167afSAl Viro err = finish_automount(mnt, path); 769ea5b778aSDavid Howells 770ea5b778aSDavid Howells switch (err) { 771ea5b778aSDavid Howells case -EBUSY: 772ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 77319a167afSAl Viro return 0; 774ea5b778aSDavid Howells case 0: 7758aef1884SAl Viro path_put(path); 7769875cf80SDavid Howells path->mnt = mnt; 7779875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 7789875cf80SDavid Howells return 0; 77919a167afSAl Viro default: 78019a167afSAl Viro return err; 7819875cf80SDavid Howells } 78219a167afSAl Viro 783ea5b778aSDavid Howells } 7849875cf80SDavid Howells 7859875cf80SDavid Howells /* 7869875cf80SDavid Howells * Handle a dentry that is managed in some way. 787cc53ce53SDavid Howells * - Flagged for transit management (autofs) 7889875cf80SDavid Howells * - Flagged as mountpoint 7899875cf80SDavid Howells * - Flagged as automount point 7909875cf80SDavid Howells * 7919875cf80SDavid Howells * This may only be called in refwalk mode. 7929875cf80SDavid Howells * 7939875cf80SDavid Howells * Serialization is taken care of in namespace.c 7949875cf80SDavid Howells */ 7959875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 7969875cf80SDavid Howells { 7978aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 7989875cf80SDavid Howells unsigned managed; 7999875cf80SDavid Howells bool need_mntput = false; 8008aef1884SAl Viro int ret = 0; 8019875cf80SDavid Howells 8029875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 8039875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 8049875cf80SDavid Howells * the components of that value change under us */ 8059875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 8069875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 8079875cf80SDavid Howells unlikely(managed != 0)) { 808cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 809cc53ce53SDavid Howells * being held. */ 810cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 811cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 812cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 8131aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 814cc53ce53SDavid Howells if (ret < 0) 8158aef1884SAl Viro break; 816cc53ce53SDavid Howells } 817cc53ce53SDavid Howells 8189875cf80SDavid Howells /* Transit to a mounted filesystem. */ 8199875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 8209875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 8219875cf80SDavid Howells if (mounted) { 8229875cf80SDavid Howells dput(path->dentry); 8239875cf80SDavid Howells if (need_mntput) 824463ffb2eSAl Viro mntput(path->mnt); 825463ffb2eSAl Viro path->mnt = mounted; 826463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 8279875cf80SDavid Howells need_mntput = true; 8289875cf80SDavid Howells continue; 829463ffb2eSAl Viro } 830463ffb2eSAl Viro 8319875cf80SDavid Howells /* Something is mounted on this dentry in another 8329875cf80SDavid Howells * namespace and/or whatever was mounted there in this 8339875cf80SDavid Howells * namespace got unmounted before we managed to get the 8349875cf80SDavid Howells * vfsmount_lock */ 8351da177e4SLinus Torvalds } 8369875cf80SDavid Howells 8379875cf80SDavid Howells /* Handle an automount point */ 8389875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 8399875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 8409875cf80SDavid Howells if (ret < 0) 8418aef1884SAl Viro break; 8429875cf80SDavid Howells continue; 8439875cf80SDavid Howells } 8449875cf80SDavid Howells 8459875cf80SDavid Howells /* We didn't change the current path point */ 8469875cf80SDavid Howells break; 8479875cf80SDavid Howells } 8488aef1884SAl Viro 8498aef1884SAl Viro if (need_mntput && path->mnt == mnt) 8508aef1884SAl Viro mntput(path->mnt); 8518aef1884SAl Viro if (ret == -EISDIR) 8528aef1884SAl Viro ret = 0; 8538aef1884SAl Viro return ret; 8541da177e4SLinus Torvalds } 8551da177e4SLinus Torvalds 856cc53ce53SDavid Howells int follow_down_one(struct path *path) 8571da177e4SLinus Torvalds { 8581da177e4SLinus Torvalds struct vfsmount *mounted; 8591da177e4SLinus Torvalds 8601c755af4SAl Viro mounted = lookup_mnt(path); 8611da177e4SLinus Torvalds if (mounted) { 8629393bd07SAl Viro dput(path->dentry); 8639393bd07SAl Viro mntput(path->mnt); 8649393bd07SAl Viro path->mnt = mounted; 8659393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 8661da177e4SLinus Torvalds return 1; 8671da177e4SLinus Torvalds } 8681da177e4SLinus Torvalds return 0; 8691da177e4SLinus Torvalds } 8701da177e4SLinus Torvalds 87162a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 87262a7375eSIan Kent { 87362a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 87462a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 87562a7375eSIan Kent } 87662a7375eSIan Kent 8779875cf80SDavid Howells /* 878287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 879287548e4SAl Viro * we meet a managed dentry that would need blocking. 8809875cf80SDavid Howells */ 8819875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 882287548e4SAl Viro struct inode **inode) 8839875cf80SDavid Howells { 88462a7375eSIan Kent for (;;) { 8859875cf80SDavid Howells struct vfsmount *mounted; 88662a7375eSIan Kent /* 88762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 88862a7375eSIan Kent * that wants to block transit. 88962a7375eSIan Kent */ 890287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 891ab90911fSDavid Howells return false; 89262a7375eSIan Kent 89362a7375eSIan Kent if (!d_mountpoint(path->dentry)) 89462a7375eSIan Kent break; 89562a7375eSIan Kent 8969875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 8979875cf80SDavid Howells if (!mounted) 8989875cf80SDavid Howells break; 8999875cf80SDavid Howells path->mnt = mounted; 9009875cf80SDavid Howells path->dentry = mounted->mnt_root; 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)) { 915287548e4SAl Viro struct vfsmount *mounted; 916dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 917287548e4SAl Viro if (!mounted) 918287548e4SAl Viro break; 919dea39376SAl Viro nd->path.mnt = mounted; 920dea39376SAl Viro nd->path.dentry = mounted->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 /* 1053baa03890SNick Piggin * Allocate a dentry with name and parent, and perform a parent 1054baa03890SNick Piggin * directory ->lookup on it. Returns the new dentry, or ERR_PTR 1055baa03890SNick Piggin * on error. parent->d_inode->i_mutex must be held. d_lookup must 1056baa03890SNick Piggin * have verified that no child exists while under i_mutex. 1057baa03890SNick Piggin */ 1058baa03890SNick Piggin static struct dentry *d_alloc_and_lookup(struct dentry *parent, 1059baa03890SNick Piggin struct qstr *name, struct nameidata *nd) 1060baa03890SNick Piggin { 1061baa03890SNick Piggin struct inode *inode = parent->d_inode; 1062baa03890SNick Piggin struct dentry *dentry; 1063baa03890SNick Piggin struct dentry *old; 1064baa03890SNick Piggin 1065baa03890SNick Piggin /* Don't create child dentry for a dead directory. */ 1066baa03890SNick Piggin if (unlikely(IS_DEADDIR(inode))) 1067baa03890SNick Piggin return ERR_PTR(-ENOENT); 1068baa03890SNick Piggin 1069baa03890SNick Piggin dentry = d_alloc(parent, name); 1070baa03890SNick Piggin if (unlikely(!dentry)) 1071baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1072baa03890SNick Piggin 1073baa03890SNick Piggin old = inode->i_op->lookup(inode, dentry, nd); 1074baa03890SNick Piggin if (unlikely(old)) { 1075baa03890SNick Piggin dput(dentry); 1076baa03890SNick Piggin dentry = old; 1077baa03890SNick Piggin } 1078baa03890SNick Piggin return dentry; 1079baa03890SNick Piggin } 1080baa03890SNick Piggin 1081baa03890SNick Piggin /* 108244396f4bSJosef Bacik * We already have a dentry, but require a lookup to be performed on the parent 108344396f4bSJosef Bacik * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. 108444396f4bSJosef Bacik * parent->d_inode->i_mutex must be held. d_lookup must have verified that no 108544396f4bSJosef Bacik * child exists while under i_mutex. 108644396f4bSJosef Bacik */ 108744396f4bSJosef Bacik static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, 108844396f4bSJosef Bacik struct nameidata *nd) 108944396f4bSJosef Bacik { 109044396f4bSJosef Bacik struct inode *inode = parent->d_inode; 109144396f4bSJosef Bacik struct dentry *old; 109244396f4bSJosef Bacik 109344396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 109444396f4bSJosef Bacik if (unlikely(IS_DEADDIR(inode))) 109544396f4bSJosef Bacik return ERR_PTR(-ENOENT); 109644396f4bSJosef Bacik 109744396f4bSJosef Bacik old = inode->i_op->lookup(inode, dentry, nd); 109844396f4bSJosef Bacik if (unlikely(old)) { 109944396f4bSJosef Bacik dput(dentry); 110044396f4bSJosef Bacik dentry = old; 110144396f4bSJosef Bacik } 110244396f4bSJosef Bacik return dentry; 110344396f4bSJosef Bacik } 110444396f4bSJosef Bacik 110544396f4bSJosef Bacik /* 11061da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 11071da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 11081da177e4SLinus Torvalds * It _is_ time-critical. 11091da177e4SLinus Torvalds */ 11101da177e4SLinus Torvalds static int do_lookup(struct nameidata *nd, struct qstr *name, 111131e6b01fSNick Piggin struct path *path, struct inode **inode) 11121da177e4SLinus Torvalds { 11134ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 111431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 11155a18fff2SAl Viro int need_reval = 1; 11165a18fff2SAl Viro int status = 1; 11179875cf80SDavid Howells int err; 11189875cf80SDavid Howells 11193cac260aSAl Viro /* 1120b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1121b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1122b04f784eSNick Piggin * do the non-racy lookup, below. 1123b04f784eSNick Piggin */ 112431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 112531e6b01fSNick Piggin unsigned seq; 112631e6b01fSNick Piggin *inode = nd->inode; 112731e6b01fSNick Piggin dentry = __d_lookup_rcu(parent, name, &seq, inode); 11285a18fff2SAl Viro if (!dentry) 11295a18fff2SAl Viro goto unlazy; 11305a18fff2SAl Viro 113131e6b01fSNick Piggin /* Memory barrier in read_seqcount_begin of child is enough */ 113231e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 113331e6b01fSNick Piggin return -ECHILD; 113431e6b01fSNick Piggin nd->seq = seq; 11355a18fff2SAl Viro 113624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 11375a18fff2SAl Viro status = d_revalidate(dentry, nd); 11385a18fff2SAl Viro if (unlikely(status <= 0)) { 11395a18fff2SAl Viro if (status != -ECHILD) 11405a18fff2SAl Viro need_reval = 0; 11415a18fff2SAl Viro goto unlazy; 11425a18fff2SAl Viro } 114324643087SAl Viro } 114444396f4bSJosef Bacik if (unlikely(d_need_lookup(dentry))) 114544396f4bSJosef Bacik goto unlazy; 114631e6b01fSNick Piggin path->mnt = mnt; 114731e6b01fSNick Piggin path->dentry = dentry; 1148d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1149d6e9bd25SAl Viro goto unlazy; 1150d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1151d6e9bd25SAl Viro goto unlazy; 11529875cf80SDavid Howells return 0; 11535a18fff2SAl Viro unlazy: 115419660af7SAl Viro if (unlazy_walk(nd, dentry)) 11555a18fff2SAl Viro return -ECHILD; 11565a18fff2SAl Viro } else { 115731e6b01fSNick Piggin dentry = __d_lookup(parent, name); 115824643087SAl Viro } 11595a18fff2SAl Viro 116044396f4bSJosef Bacik if (dentry && unlikely(d_need_lookup(dentry))) { 116144396f4bSJosef Bacik dput(dentry); 116244396f4bSJosef Bacik dentry = NULL; 116344396f4bSJosef Bacik } 11645a18fff2SAl Viro retry: 11655a18fff2SAl Viro if (unlikely(!dentry)) { 11665a18fff2SAl Viro struct inode *dir = parent->d_inode; 11675a18fff2SAl Viro BUG_ON(nd->inode != dir); 11685a18fff2SAl Viro 11695a18fff2SAl Viro mutex_lock(&dir->i_mutex); 11705a18fff2SAl Viro dentry = d_lookup(parent, name); 11715a18fff2SAl Viro if (likely(!dentry)) { 11725a18fff2SAl Viro dentry = d_alloc_and_lookup(parent, name, nd); 11735a18fff2SAl Viro if (IS_ERR(dentry)) { 11745a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11755a18fff2SAl Viro return PTR_ERR(dentry); 11765a18fff2SAl Viro } 11775a18fff2SAl Viro /* known good */ 11785a18fff2SAl Viro need_reval = 0; 11795a18fff2SAl Viro status = 1; 118044396f4bSJosef Bacik } else if (unlikely(d_need_lookup(dentry))) { 118144396f4bSJosef Bacik dentry = d_inode_lookup(parent, dentry, nd); 118244396f4bSJosef Bacik if (IS_ERR(dentry)) { 118344396f4bSJosef Bacik mutex_unlock(&dir->i_mutex); 118444396f4bSJosef Bacik return PTR_ERR(dentry); 118544396f4bSJosef Bacik } 118644396f4bSJosef Bacik /* known good */ 118744396f4bSJosef Bacik need_reval = 0; 118844396f4bSJosef Bacik status = 1; 11895a18fff2SAl Viro } 11905a18fff2SAl Viro mutex_unlock(&dir->i_mutex); 11915a18fff2SAl Viro } 11925a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 11935a18fff2SAl Viro status = d_revalidate(dentry, nd); 11945a18fff2SAl Viro if (unlikely(status <= 0)) { 11955a18fff2SAl Viro if (status < 0) { 11965a18fff2SAl Viro dput(dentry); 11975a18fff2SAl Viro return status; 11985a18fff2SAl Viro } 11995a18fff2SAl Viro if (!d_invalidate(dentry)) { 12005a18fff2SAl Viro dput(dentry); 12015a18fff2SAl Viro dentry = NULL; 12025a18fff2SAl Viro need_reval = 1; 12035a18fff2SAl Viro goto retry; 12045a18fff2SAl Viro } 12055a18fff2SAl Viro } 12065a18fff2SAl Viro 12071da177e4SLinus Torvalds path->mnt = mnt; 12081da177e4SLinus Torvalds path->dentry = dentry; 12099875cf80SDavid Howells err = follow_managed(path, nd->flags); 121089312214SIan Kent if (unlikely(err < 0)) { 121189312214SIan Kent path_put_conditional(path, nd); 12129875cf80SDavid Howells return err; 121389312214SIan Kent } 121431e6b01fSNick Piggin *inode = path->dentry->d_inode; 12151da177e4SLinus Torvalds return 0; 12161da177e4SLinus Torvalds } 12171da177e4SLinus Torvalds 121852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 121952094c8aSAl Viro { 122052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 12214ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 122252094c8aSAl Viro if (err != -ECHILD) 122352094c8aSAl Viro return err; 122419660af7SAl Viro if (unlazy_walk(nd, NULL)) 122552094c8aSAl Viro return -ECHILD; 122652094c8aSAl Viro } 12274ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 122852094c8aSAl Viro } 122952094c8aSAl Viro 12309856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 12319856fa1bSAl Viro { 12329856fa1bSAl Viro if (type == LAST_DOTDOT) { 12339856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 12349856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 12359856fa1bSAl Viro return -ECHILD; 12369856fa1bSAl Viro } else 12379856fa1bSAl Viro follow_dotdot(nd); 12389856fa1bSAl Viro } 12399856fa1bSAl Viro return 0; 12409856fa1bSAl Viro } 12419856fa1bSAl Viro 1242951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1243951361f9SAl Viro { 1244951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1245951361f9SAl Viro path_put(&nd->path); 1246951361f9SAl Viro } else { 1247951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 12485b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1249951361f9SAl Viro nd->root.mnt = NULL; 1250951361f9SAl Viro rcu_read_unlock(); 1251951361f9SAl Viro br_read_unlock(vfsmount_lock); 1252951361f9SAl Viro } 1253951361f9SAl Viro } 1254951361f9SAl Viro 12553ddcd056SLinus Torvalds /* 12563ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 12573ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 12583ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 12593ddcd056SLinus Torvalds * for the common case. 12603ddcd056SLinus Torvalds */ 12617813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 12623ddcd056SLinus Torvalds { 12633ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 12643ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 12653ddcd056SLinus Torvalds return follow; 12663ddcd056SLinus Torvalds 12673ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 12683ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 12693ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 12703ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 12713ddcd056SLinus Torvalds } 12723ddcd056SLinus Torvalds return 0; 12733ddcd056SLinus Torvalds } 12743ddcd056SLinus Torvalds 1275ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 1276ce57dfc1SAl Viro struct qstr *name, int type, int follow) 1277ce57dfc1SAl Viro { 1278ce57dfc1SAl Viro struct inode *inode; 1279ce57dfc1SAl Viro int err; 1280ce57dfc1SAl Viro /* 1281ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1282ce57dfc1SAl Viro * to be able to know about the current root directory and 1283ce57dfc1SAl Viro * parent relationships. 1284ce57dfc1SAl Viro */ 1285ce57dfc1SAl Viro if (unlikely(type != LAST_NORM)) 1286ce57dfc1SAl Viro return handle_dots(nd, type); 1287ce57dfc1SAl Viro err = do_lookup(nd, name, path, &inode); 1288ce57dfc1SAl Viro if (unlikely(err)) { 1289ce57dfc1SAl Viro terminate_walk(nd); 1290ce57dfc1SAl Viro return err; 1291ce57dfc1SAl Viro } 1292ce57dfc1SAl Viro if (!inode) { 1293ce57dfc1SAl Viro path_to_nameidata(path, nd); 1294ce57dfc1SAl Viro terminate_walk(nd); 1295ce57dfc1SAl Viro return -ENOENT; 1296ce57dfc1SAl Viro } 12977813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 129819660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 129919660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 130019660af7SAl Viro terminate_walk(nd); 1301ce57dfc1SAl Viro return -ECHILD; 130219660af7SAl Viro } 130319660af7SAl Viro } 1304ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1305ce57dfc1SAl Viro return 1; 1306ce57dfc1SAl Viro } 1307ce57dfc1SAl Viro path_to_nameidata(path, nd); 1308ce57dfc1SAl Viro nd->inode = inode; 1309ce57dfc1SAl Viro return 0; 1310ce57dfc1SAl Viro } 1311ce57dfc1SAl Viro 13121da177e4SLinus Torvalds /* 1313b356379aSAl Viro * This limits recursive symlink follows to 8, while 1314b356379aSAl Viro * limiting consecutive symlinks to 40. 1315b356379aSAl Viro * 1316b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1317b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1318b356379aSAl Viro */ 1319b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1320b356379aSAl Viro { 1321b356379aSAl Viro int res; 1322b356379aSAl Viro 1323b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1324b356379aSAl Viro path_put_conditional(path, nd); 1325b356379aSAl Viro path_put(&nd->path); 1326b356379aSAl Viro return -ELOOP; 1327b356379aSAl Viro } 13281a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1329b356379aSAl Viro 1330b356379aSAl Viro nd->depth++; 1331b356379aSAl Viro current->link_count++; 1332b356379aSAl Viro 1333b356379aSAl Viro do { 1334b356379aSAl Viro struct path link = *path; 1335b356379aSAl Viro void *cookie; 1336574197e0SAl Viro 1337574197e0SAl Viro res = follow_link(&link, nd, &cookie); 1338b356379aSAl Viro if (!res) 1339b356379aSAl Viro res = walk_component(nd, path, &nd->last, 1340b356379aSAl Viro nd->last_type, LOOKUP_FOLLOW); 1341574197e0SAl Viro put_link(nd, &link, cookie); 1342b356379aSAl Viro } while (res > 0); 1343b356379aSAl Viro 1344b356379aSAl Viro current->link_count--; 1345b356379aSAl Viro nd->depth--; 1346b356379aSAl Viro return res; 1347b356379aSAl Viro } 1348b356379aSAl Viro 1349b356379aSAl Viro /* 13503ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 13513ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 13523ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 13533ddcd056SLinus Torvalds * do lookup on this inode". 13543ddcd056SLinus Torvalds */ 13553ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 13563ddcd056SLinus Torvalds { 13573ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 13583ddcd056SLinus Torvalds return 1; 13593ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 13603ddcd056SLinus Torvalds return 0; 13613ddcd056SLinus Torvalds 13623ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 13633ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 13643ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 13653ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 13663ddcd056SLinus Torvalds return 1; 13673ddcd056SLinus Torvalds } 13683ddcd056SLinus Torvalds 13693ddcd056SLinus Torvalds /* 13701da177e4SLinus Torvalds * Name resolution. 1371ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1372ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 13731da177e4SLinus Torvalds * 1374ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1375ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 13761da177e4SLinus Torvalds */ 13776de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 13781da177e4SLinus Torvalds { 13791da177e4SLinus Torvalds struct path next; 13801da177e4SLinus Torvalds int err; 13811da177e4SLinus Torvalds 13821da177e4SLinus Torvalds while (*name=='/') 13831da177e4SLinus Torvalds name++; 13841da177e4SLinus Torvalds if (!*name) 1385086e183aSAl Viro return 0; 13861da177e4SLinus Torvalds 13871da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 13881da177e4SLinus Torvalds for(;;) { 13891da177e4SLinus Torvalds unsigned long hash; 13901da177e4SLinus Torvalds struct qstr this; 13911da177e4SLinus Torvalds unsigned int c; 1392fe479a58SAl Viro int type; 13931da177e4SLinus Torvalds 139452094c8aSAl Viro err = may_lookup(nd); 13951da177e4SLinus Torvalds if (err) 13961da177e4SLinus Torvalds break; 13971da177e4SLinus Torvalds 13981da177e4SLinus Torvalds this.name = name; 13991da177e4SLinus Torvalds c = *(const unsigned char *)name; 14001da177e4SLinus Torvalds 14011da177e4SLinus Torvalds hash = init_name_hash(); 14021da177e4SLinus Torvalds do { 14031da177e4SLinus Torvalds name++; 14041da177e4SLinus Torvalds hash = partial_name_hash(c, hash); 14051da177e4SLinus Torvalds c = *(const unsigned char *)name; 14061da177e4SLinus Torvalds } while (c && (c != '/')); 14071da177e4SLinus Torvalds this.len = name - (const char *) this.name; 14081da177e4SLinus Torvalds this.hash = end_name_hash(hash); 14091da177e4SLinus Torvalds 1410fe479a58SAl Viro type = LAST_NORM; 1411fe479a58SAl Viro if (this.name[0] == '.') switch (this.len) { 1412fe479a58SAl Viro case 2: 141316c2cd71SAl Viro if (this.name[1] == '.') { 1414fe479a58SAl Viro type = LAST_DOTDOT; 141516c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 141616c2cd71SAl Viro } 1417fe479a58SAl Viro break; 1418fe479a58SAl Viro case 1: 1419fe479a58SAl Viro type = LAST_DOT; 1420fe479a58SAl Viro } 14215a202bcdSAl Viro if (likely(type == LAST_NORM)) { 14225a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 142316c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 14245a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 14255a202bcdSAl Viro err = parent->d_op->d_hash(parent, nd->inode, 14265a202bcdSAl Viro &this); 14275a202bcdSAl Viro if (err < 0) 14285a202bcdSAl Viro break; 14295a202bcdSAl Viro } 14305a202bcdSAl Viro } 1431fe479a58SAl Viro 14321da177e4SLinus Torvalds /* remove trailing slashes? */ 14331da177e4SLinus Torvalds if (!c) 14341da177e4SLinus Torvalds goto last_component; 14351da177e4SLinus Torvalds while (*++name == '/'); 14361da177e4SLinus Torvalds if (!*name) 1437b356379aSAl Viro goto last_component; 14381da177e4SLinus Torvalds 1439ce57dfc1SAl Viro err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); 1440ce57dfc1SAl Viro if (err < 0) 1441ce57dfc1SAl Viro return err; 1442fe479a58SAl Viro 1443ce57dfc1SAl Viro if (err) { 1444b356379aSAl Viro err = nested_symlink(&next, nd); 14451da177e4SLinus Torvalds if (err) 1446a7472babSAl Viro return err; 144731e6b01fSNick Piggin } 14483ddcd056SLinus Torvalds if (can_lookup(nd->inode)) 14491da177e4SLinus Torvalds continue; 14503ddcd056SLinus Torvalds err = -ENOTDIR; 14513ddcd056SLinus Torvalds break; 14521da177e4SLinus Torvalds /* here ends the main loop */ 14531da177e4SLinus Torvalds 14541da177e4SLinus Torvalds last_component: 1455ce57dfc1SAl Viro nd->last = this; 1456ce57dfc1SAl Viro nd->last_type = type; 1457ce57dfc1SAl Viro return 0; 1458ce57dfc1SAl Viro } 1459951361f9SAl Viro terminate_walk(nd); 14601da177e4SLinus Torvalds return err; 14611da177e4SLinus Torvalds } 14621da177e4SLinus Torvalds 146370e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 146470e9b357SAl Viro struct nameidata *nd, struct file **fp) 146531e6b01fSNick Piggin { 146631e6b01fSNick Piggin int retval = 0; 146731e6b01fSNick Piggin int fput_needed; 146831e6b01fSNick Piggin struct file *file; 146931e6b01fSNick Piggin 147031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 147116c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 147231e6b01fSNick Piggin nd->depth = 0; 14735b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 14745b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 147573d049a4SAl Viro if (*name) { 14765b6ca027SAl Viro if (!inode->i_op->lookup) 14775b6ca027SAl Viro return -ENOTDIR; 14785b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 14795b6ca027SAl Viro if (retval) 14805b6ca027SAl Viro return retval; 148173d049a4SAl Viro } 14825b6ca027SAl Viro nd->path = nd->root; 14835b6ca027SAl Viro nd->inode = inode; 14845b6ca027SAl Viro if (flags & LOOKUP_RCU) { 14855b6ca027SAl Viro br_read_lock(vfsmount_lock); 14865b6ca027SAl Viro rcu_read_lock(); 14875b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 14885b6ca027SAl Viro } else { 14895b6ca027SAl Viro path_get(&nd->path); 14905b6ca027SAl Viro } 14915b6ca027SAl Viro return 0; 14925b6ca027SAl Viro } 14935b6ca027SAl Viro 149431e6b01fSNick Piggin nd->root.mnt = NULL; 149531e6b01fSNick Piggin 149631e6b01fSNick Piggin if (*name=='/') { 1497e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 149831e6b01fSNick Piggin br_read_lock(vfsmount_lock); 149931e6b01fSNick Piggin rcu_read_lock(); 1500e41f7d4eSAl Viro set_root_rcu(nd); 1501e41f7d4eSAl Viro } else { 1502e41f7d4eSAl Viro set_root(nd); 1503e41f7d4eSAl Viro path_get(&nd->root); 1504e41f7d4eSAl Viro } 150531e6b01fSNick Piggin nd->path = nd->root; 150631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1507e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 150831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1509c28cc364SNick Piggin unsigned seq; 151031e6b01fSNick Piggin 151131e6b01fSNick Piggin br_read_lock(vfsmount_lock); 151231e6b01fSNick Piggin rcu_read_lock(); 151331e6b01fSNick Piggin 1514c28cc364SNick Piggin do { 1515c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 151631e6b01fSNick Piggin nd->path = fs->pwd; 1517c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1518c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1519e41f7d4eSAl Viro } else { 1520e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1521e41f7d4eSAl Viro } 152231e6b01fSNick Piggin } else { 152331e6b01fSNick Piggin struct dentry *dentry; 152431e6b01fSNick Piggin 15251abf0c71SAl Viro file = fget_raw_light(dfd, &fput_needed); 152631e6b01fSNick Piggin retval = -EBADF; 152731e6b01fSNick Piggin if (!file) 152831e6b01fSNick Piggin goto out_fail; 152931e6b01fSNick Piggin 153031e6b01fSNick Piggin dentry = file->f_path.dentry; 153131e6b01fSNick Piggin 1532f52e0c11SAl Viro if (*name) { 153331e6b01fSNick Piggin retval = -ENOTDIR; 153431e6b01fSNick Piggin if (!S_ISDIR(dentry->d_inode->i_mode)) 153531e6b01fSNick Piggin goto fput_fail; 153631e6b01fSNick Piggin 15374ad5abb3SAl Viro retval = inode_permission(dentry->d_inode, MAY_EXEC); 153831e6b01fSNick Piggin if (retval) 153931e6b01fSNick Piggin goto fput_fail; 1540f52e0c11SAl Viro } 154131e6b01fSNick Piggin 154231e6b01fSNick Piggin nd->path = file->f_path; 1543e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 154431e6b01fSNick Piggin if (fput_needed) 154570e9b357SAl Viro *fp = file; 1546c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 154731e6b01fSNick Piggin br_read_lock(vfsmount_lock); 154831e6b01fSNick Piggin rcu_read_lock(); 15495590ff0dSUlrich Drepper } else { 15505dd784d0SJan Blunck path_get(&file->f_path); 15515590ff0dSUlrich Drepper fput_light(file, fput_needed); 15521da177e4SLinus Torvalds } 1553e41f7d4eSAl Viro } 1554e41f7d4eSAl Viro 155531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 15569b4a9b14SAl Viro return 0; 15572dfdd266SJosef 'Jeff' Sipek 15589b4a9b14SAl Viro fput_fail: 15599b4a9b14SAl Viro fput_light(file, fput_needed); 15609b4a9b14SAl Viro out_fail: 15619b4a9b14SAl Viro return retval; 15629b4a9b14SAl Viro } 15639b4a9b14SAl Viro 1564bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1565bd92d7feSAl Viro { 1566bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1567bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1568bd92d7feSAl Viro 1569bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1570bd92d7feSAl Viro return walk_component(nd, path, &nd->last, nd->last_type, 1571bd92d7feSAl Viro nd->flags & LOOKUP_FOLLOW); 1572bd92d7feSAl Viro } 1573bd92d7feSAl Viro 15749b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1575ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 15769b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 15779b4a9b14SAl Viro { 157870e9b357SAl Viro struct file *base = NULL; 1579bd92d7feSAl Viro struct path path; 1580bd92d7feSAl Viro int err; 158131e6b01fSNick Piggin 158231e6b01fSNick Piggin /* 158331e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 158431e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 158531e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 158631e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 158731e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 158831e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 158931e6b01fSNick Piggin * analogue, foo_rcu(). 159031e6b01fSNick Piggin * 159131e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 159231e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 159331e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 159431e6b01fSNick Piggin * be able to complete). 159531e6b01fSNick Piggin */ 1596bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1597ee0827cdSAl Viro 1598bd92d7feSAl Viro if (unlikely(err)) 1599bd92d7feSAl Viro return err; 1600ee0827cdSAl Viro 1601ee0827cdSAl Viro current->total_link_count = 0; 1602bd92d7feSAl Viro err = link_path_walk(name, nd); 1603bd92d7feSAl Viro 1604bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1605bd92d7feSAl Viro err = lookup_last(nd, &path); 1606bd92d7feSAl Viro while (err > 0) { 1607bd92d7feSAl Viro void *cookie; 1608bd92d7feSAl Viro struct path link = path; 1609bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1610574197e0SAl Viro err = follow_link(&link, nd, &cookie); 1611bd92d7feSAl Viro if (!err) 1612bd92d7feSAl Viro err = lookup_last(nd, &path); 1613574197e0SAl Viro put_link(nd, &link, cookie); 1614bd92d7feSAl Viro } 1615bd92d7feSAl Viro } 1616ee0827cdSAl Viro 16179f1fafeeSAl Viro if (!err) 16189f1fafeeSAl Viro err = complete_walk(nd); 1619bd92d7feSAl Viro 1620bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 1621bd92d7feSAl Viro if (!nd->inode->i_op->lookup) { 1622bd92d7feSAl Viro path_put(&nd->path); 1623bd23a539SAl Viro err = -ENOTDIR; 1624bd92d7feSAl Viro } 1625bd92d7feSAl Viro } 162616c2cd71SAl Viro 162770e9b357SAl Viro if (base) 162870e9b357SAl Viro fput(base); 1629ee0827cdSAl Viro 16305b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 163131e6b01fSNick Piggin path_put(&nd->root); 163231e6b01fSNick Piggin nd->root.mnt = NULL; 163331e6b01fSNick Piggin } 1634bd92d7feSAl Viro return err; 163531e6b01fSNick Piggin } 163631e6b01fSNick Piggin 1637ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 1638ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 1639ee0827cdSAl Viro { 1640ee0827cdSAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 1641ee0827cdSAl Viro if (unlikely(retval == -ECHILD)) 1642ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags, nd); 1643ee0827cdSAl Viro if (unlikely(retval == -ESTALE)) 1644ee0827cdSAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 1645ee0827cdSAl Viro 164631e6b01fSNick Piggin if (likely(!retval)) { 164731e6b01fSNick Piggin if (unlikely(!audit_dummy_context())) { 164831e6b01fSNick Piggin if (nd->path.dentry && nd->inode) 164931e6b01fSNick Piggin audit_inode(name, nd->path.dentry); 165031e6b01fSNick Piggin } 165131e6b01fSNick Piggin } 1652170aa3d0SUlrich Drepper return retval; 16531da177e4SLinus Torvalds } 16541da177e4SLinus Torvalds 1655c9c6cac0SAl Viro int kern_path_parent(const char *name, struct nameidata *nd) 16565590ff0dSUlrich Drepper { 1657c9c6cac0SAl Viro return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); 16585590ff0dSUlrich Drepper } 16595590ff0dSUlrich Drepper 1660d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 1661d1811465SAl Viro { 1662d1811465SAl Viro struct nameidata nd; 1663d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 1664d1811465SAl Viro if (!res) 1665d1811465SAl Viro *path = nd.path; 1666d1811465SAl Viro return res; 1667d1811465SAl Viro } 1668d1811465SAl Viro 166916f18200SJosef 'Jeff' Sipek /** 167016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 167116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 167216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 167316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 167416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 1675e0a01249SAl Viro * @path: pointer to struct path to fill 167616f18200SJosef 'Jeff' Sipek */ 167716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 167816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 1679e0a01249SAl Viro struct path *path) 168016f18200SJosef 'Jeff' Sipek { 1681e0a01249SAl Viro struct nameidata nd; 1682e0a01249SAl Viro int err; 1683e0a01249SAl Viro nd.root.dentry = dentry; 1684e0a01249SAl Viro nd.root.mnt = mnt; 1685e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 16865b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 1687e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 1688e0a01249SAl Viro if (!err) 1689e0a01249SAl Viro *path = nd.path; 1690e0a01249SAl Viro return err; 169116f18200SJosef 'Jeff' Sipek } 169216f18200SJosef 'Jeff' Sipek 1693eead1911SChristoph Hellwig static struct dentry *__lookup_hash(struct qstr *name, 1694eead1911SChristoph Hellwig struct dentry *base, struct nameidata *nd) 16951da177e4SLinus Torvalds { 169681fca444SChristoph Hellwig struct inode *inode = base->d_inode; 16971da177e4SLinus Torvalds struct dentry *dentry; 16981da177e4SLinus Torvalds int err; 16991da177e4SLinus Torvalds 17004ad5abb3SAl Viro err = inode_permission(inode, MAY_EXEC); 170181fca444SChristoph Hellwig if (err) 170281fca444SChristoph Hellwig return ERR_PTR(err); 17031da177e4SLinus Torvalds 17041da177e4SLinus Torvalds /* 1705b04f784eSNick Piggin * Don't bother with __d_lookup: callers are for creat as 1706b04f784eSNick Piggin * well as unlink, so a lot of the time it would cost 1707b04f784eSNick Piggin * a double lookup. 17086e6b1bd1SAl Viro */ 17096e6b1bd1SAl Viro dentry = d_lookup(base, name); 17106e6b1bd1SAl Viro 171144396f4bSJosef Bacik if (dentry && d_need_lookup(dentry)) { 171244396f4bSJosef Bacik /* 171344396f4bSJosef Bacik * __lookup_hash is called with the parent dir's i_mutex already 171444396f4bSJosef Bacik * held, so we are good to go here. 171544396f4bSJosef Bacik */ 171644396f4bSJosef Bacik dentry = d_inode_lookup(base, dentry, nd); 171744396f4bSJosef Bacik if (IS_ERR(dentry)) 171844396f4bSJosef Bacik return dentry; 171944396f4bSJosef Bacik } 172044396f4bSJosef Bacik 1721d2d9e9fbSAl Viro if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { 1722d2d9e9fbSAl Viro int status = d_revalidate(dentry, nd); 1723d2d9e9fbSAl Viro if (unlikely(status <= 0)) { 1724d2d9e9fbSAl Viro /* 1725d2d9e9fbSAl Viro * The dentry failed validation. 1726d2d9e9fbSAl Viro * If d_revalidate returned 0 attempt to invalidate 1727d2d9e9fbSAl Viro * the dentry otherwise d_revalidate is asking us 1728d2d9e9fbSAl Viro * to return a fail status. 1729d2d9e9fbSAl Viro */ 1730d2d9e9fbSAl Viro if (status < 0) { 1731d2d9e9fbSAl Viro dput(dentry); 1732d2d9e9fbSAl Viro return ERR_PTR(status); 1733d2d9e9fbSAl Viro } else if (!d_invalidate(dentry)) { 1734d2d9e9fbSAl Viro dput(dentry); 1735d2d9e9fbSAl Viro dentry = NULL; 1736d2d9e9fbSAl Viro } 1737d2d9e9fbSAl Viro } 1738d2d9e9fbSAl Viro } 17396e6b1bd1SAl Viro 17401da177e4SLinus Torvalds if (!dentry) 1741baa03890SNick Piggin dentry = d_alloc_and_lookup(base, name, nd); 17425a202bcdSAl Viro 17431da177e4SLinus Torvalds return dentry; 17441da177e4SLinus Torvalds } 17451da177e4SLinus Torvalds 1746057f6c01SJames Morris /* 1747057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 1748057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 1749057f6c01SJames Morris * SMP-safe. 1750057f6c01SJames Morris */ 1751a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 17521da177e4SLinus Torvalds { 17534ac91378SJan Blunck return __lookup_hash(&nd->last, nd->path.dentry, nd); 17541da177e4SLinus Torvalds } 17551da177e4SLinus Torvalds 1756eead1911SChristoph Hellwig /** 1757a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 1758eead1911SChristoph Hellwig * @name: pathname component to lookup 1759eead1911SChristoph Hellwig * @base: base directory to lookup from 1760eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 1761eead1911SChristoph Hellwig * 1762a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 1763a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 1764eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 1765eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 1766eead1911SChristoph Hellwig */ 1767057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 1768057f6c01SJames Morris { 1769057f6c01SJames Morris struct qstr this; 17706a96ba54SAl Viro unsigned long hash; 17716a96ba54SAl Viro unsigned int c; 1772057f6c01SJames Morris 17732f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 17742f9092e1SDavid Woodhouse 17756a96ba54SAl Viro this.name = name; 17766a96ba54SAl Viro this.len = len; 17776a96ba54SAl Viro if (!len) 17786a96ba54SAl Viro return ERR_PTR(-EACCES); 17796a96ba54SAl Viro 17806a96ba54SAl Viro hash = init_name_hash(); 17816a96ba54SAl Viro while (len--) { 17826a96ba54SAl Viro c = *(const unsigned char *)name++; 17836a96ba54SAl Viro if (c == '/' || c == '\0') 17846a96ba54SAl Viro return ERR_PTR(-EACCES); 17856a96ba54SAl Viro hash = partial_name_hash(c, hash); 17866a96ba54SAl Viro } 17876a96ba54SAl Viro this.hash = end_name_hash(hash); 17885a202bcdSAl Viro /* 17895a202bcdSAl Viro * See if the low-level filesystem might want 17905a202bcdSAl Viro * to use its own hash.. 17915a202bcdSAl Viro */ 17925a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 17935a202bcdSAl Viro int err = base->d_op->d_hash(base, base->d_inode, &this); 17945a202bcdSAl Viro if (err < 0) 17955a202bcdSAl Viro return ERR_PTR(err); 17965a202bcdSAl Viro } 1797eead1911SChristoph Hellwig 179849705b77SChristoph Hellwig return __lookup_hash(&this, base, NULL); 1799057f6c01SJames Morris } 1800057f6c01SJames Morris 18012d8f3038SAl Viro int user_path_at(int dfd, const char __user *name, unsigned flags, 18022d8f3038SAl Viro struct path *path) 18031da177e4SLinus Torvalds { 18042d8f3038SAl Viro struct nameidata nd; 1805f52e0c11SAl Viro char *tmp = getname_flags(name, flags); 18061da177e4SLinus Torvalds int err = PTR_ERR(tmp); 18071da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 18082d8f3038SAl Viro 18092d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 18102d8f3038SAl Viro 18112d8f3038SAl Viro err = do_path_lookup(dfd, tmp, flags, &nd); 18121da177e4SLinus Torvalds putname(tmp); 18132d8f3038SAl Viro if (!err) 18142d8f3038SAl Viro *path = nd.path; 18151da177e4SLinus Torvalds } 18161da177e4SLinus Torvalds return err; 18171da177e4SLinus Torvalds } 18181da177e4SLinus Torvalds 18192ad94ae6SAl Viro static int user_path_parent(int dfd, const char __user *path, 18202ad94ae6SAl Viro struct nameidata *nd, char **name) 18212ad94ae6SAl Viro { 18222ad94ae6SAl Viro char *s = getname(path); 18232ad94ae6SAl Viro int error; 18242ad94ae6SAl Viro 18252ad94ae6SAl Viro if (IS_ERR(s)) 18262ad94ae6SAl Viro return PTR_ERR(s); 18272ad94ae6SAl Viro 18282ad94ae6SAl Viro error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); 18292ad94ae6SAl Viro if (error) 18302ad94ae6SAl Viro putname(s); 18312ad94ae6SAl Viro else 18322ad94ae6SAl Viro *name = s; 18332ad94ae6SAl Viro 18342ad94ae6SAl Viro return error; 18352ad94ae6SAl Viro } 18362ad94ae6SAl Viro 18371da177e4SLinus Torvalds /* 18381da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 18391da177e4SLinus Torvalds * minimal. 18401da177e4SLinus Torvalds */ 18411da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 18421da177e4SLinus Torvalds { 1843da9592edSDavid Howells uid_t fsuid = current_fsuid(); 1844da9592edSDavid Howells 18451da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 18461da177e4SLinus Torvalds return 0; 1847e795b717SSerge E. Hallyn if (current_user_ns() != inode_userns(inode)) 1848e795b717SSerge E. Hallyn goto other_userns; 1849da9592edSDavid Howells if (inode->i_uid == fsuid) 18501da177e4SLinus Torvalds return 0; 1851da9592edSDavid Howells if (dir->i_uid == fsuid) 18521da177e4SLinus Torvalds return 0; 1853e795b717SSerge E. Hallyn 1854e795b717SSerge E. Hallyn other_userns: 1855e795b717SSerge E. Hallyn return !ns_capable(inode_userns(inode), CAP_FOWNER); 18561da177e4SLinus Torvalds } 18571da177e4SLinus Torvalds 18581da177e4SLinus Torvalds /* 18591da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 18601da177e4SLinus Torvalds * whether the type of victim is right. 18611da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 18621da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 18631da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 18641da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 18651da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 18661da177e4SLinus Torvalds * a. be owner of dir, or 18671da177e4SLinus Torvalds * b. be owner of victim, or 18681da177e4SLinus Torvalds * c. have CAP_FOWNER capability 18691da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 18701da177e4SLinus Torvalds * links pointing to it. 18711da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 18721da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 18731da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 18741da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 18751da177e4SLinus Torvalds * nfs_async_unlink(). 18761da177e4SLinus Torvalds */ 1877858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 18781da177e4SLinus Torvalds { 18791da177e4SLinus Torvalds int error; 18801da177e4SLinus Torvalds 18811da177e4SLinus Torvalds if (!victim->d_inode) 18821da177e4SLinus Torvalds return -ENOENT; 18831da177e4SLinus Torvalds 18841da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 1885cccc6bbaSAl Viro audit_inode_child(victim, dir); 18861da177e4SLinus Torvalds 1887f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 18881da177e4SLinus Torvalds if (error) 18891da177e4SLinus Torvalds return error; 18901da177e4SLinus Torvalds if (IS_APPEND(dir)) 18911da177e4SLinus Torvalds return -EPERM; 18921da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 1893f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 18941da177e4SLinus Torvalds return -EPERM; 18951da177e4SLinus Torvalds if (isdir) { 18961da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 18971da177e4SLinus Torvalds return -ENOTDIR; 18981da177e4SLinus Torvalds if (IS_ROOT(victim)) 18991da177e4SLinus Torvalds return -EBUSY; 19001da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 19011da177e4SLinus Torvalds return -EISDIR; 19021da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19031da177e4SLinus Torvalds return -ENOENT; 19041da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 19051da177e4SLinus Torvalds return -EBUSY; 19061da177e4SLinus Torvalds return 0; 19071da177e4SLinus Torvalds } 19081da177e4SLinus Torvalds 19091da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 19101da177e4SLinus Torvalds * dir. 19111da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 19121da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 19131da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 19141da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 19151da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 19161da177e4SLinus Torvalds */ 1917a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 19181da177e4SLinus Torvalds { 19191da177e4SLinus Torvalds if (child->d_inode) 19201da177e4SLinus Torvalds return -EEXIST; 19211da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 19221da177e4SLinus Torvalds return -ENOENT; 1923f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 19241da177e4SLinus Torvalds } 19251da177e4SLinus Torvalds 19261da177e4SLinus Torvalds /* 19271da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 19281da177e4SLinus Torvalds */ 19291da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 19301da177e4SLinus Torvalds { 19311da177e4SLinus Torvalds struct dentry *p; 19321da177e4SLinus Torvalds 19331da177e4SLinus Torvalds if (p1 == p2) { 1934f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 19351da177e4SLinus Torvalds return NULL; 19361da177e4SLinus Torvalds } 19371da177e4SLinus Torvalds 1938a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19391da177e4SLinus Torvalds 1940e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 1941e2761a11SOGAWA Hirofumi if (p) { 1942f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 1943f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 19441da177e4SLinus Torvalds return p; 19451da177e4SLinus Torvalds } 19461da177e4SLinus Torvalds 1947e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 1948e2761a11SOGAWA Hirofumi if (p) { 1949f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1950f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19511da177e4SLinus Torvalds return p; 19521da177e4SLinus Torvalds } 19531da177e4SLinus Torvalds 1954f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 1955f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 19561da177e4SLinus Torvalds return NULL; 19571da177e4SLinus Torvalds } 19581da177e4SLinus Torvalds 19591da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 19601da177e4SLinus Torvalds { 19611b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 19621da177e4SLinus Torvalds if (p1 != p2) { 19631b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 1964a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 19651da177e4SLinus Torvalds } 19661da177e4SLinus Torvalds } 19671da177e4SLinus Torvalds 19681da177e4SLinus Torvalds int vfs_create(struct inode *dir, struct dentry *dentry, int mode, 19691da177e4SLinus Torvalds struct nameidata *nd) 19701da177e4SLinus Torvalds { 1971a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 19721da177e4SLinus Torvalds 19731da177e4SLinus Torvalds if (error) 19741da177e4SLinus Torvalds return error; 19751da177e4SLinus Torvalds 1976acfa4380SAl Viro if (!dir->i_op->create) 19771da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 19781da177e4SLinus Torvalds mode &= S_IALLUGO; 19791da177e4SLinus Torvalds mode |= S_IFREG; 19801da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 19811da177e4SLinus Torvalds if (error) 19821da177e4SLinus Torvalds return error; 19831da177e4SLinus Torvalds error = dir->i_op->create(dir, dentry, mode, nd); 1984a74574aaSStephen Smalley if (!error) 1985f38aa942SAmy Griffis fsnotify_create(dir, dentry); 19861da177e4SLinus Torvalds return error; 19871da177e4SLinus Torvalds } 19881da177e4SLinus Torvalds 198973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 19901da177e4SLinus Torvalds { 19913fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 19921da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 19931da177e4SLinus Torvalds int error; 19941da177e4SLinus Torvalds 1995bcda7652SAl Viro /* O_PATH? */ 1996bcda7652SAl Viro if (!acc_mode) 1997bcda7652SAl Viro return 0; 1998bcda7652SAl Viro 19991da177e4SLinus Torvalds if (!inode) 20001da177e4SLinus Torvalds return -ENOENT; 20011da177e4SLinus Torvalds 2002c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2003c8fe8f30SChristoph Hellwig case S_IFLNK: 20041da177e4SLinus Torvalds return -ELOOP; 2005c8fe8f30SChristoph Hellwig case S_IFDIR: 2006c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 20071da177e4SLinus Torvalds return -EISDIR; 2008c8fe8f30SChristoph Hellwig break; 2009c8fe8f30SChristoph Hellwig case S_IFBLK: 2010c8fe8f30SChristoph Hellwig case S_IFCHR: 20113fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 20121da177e4SLinus Torvalds return -EACCES; 2013c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2014c8fe8f30SChristoph Hellwig case S_IFIFO: 2015c8fe8f30SChristoph Hellwig case S_IFSOCK: 20161da177e4SLinus Torvalds flag &= ~O_TRUNC; 2017c8fe8f30SChristoph Hellwig break; 20184a3fd211SDave Hansen } 2019b41572e9SDave Hansen 20203fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2021b41572e9SDave Hansen if (error) 2022b41572e9SDave Hansen return error; 20236146f0d5SMimi Zohar 20241da177e4SLinus Torvalds /* 20251da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 20261da177e4SLinus Torvalds */ 20271da177e4SLinus Torvalds if (IS_APPEND(inode)) { 20288737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 20297715b521SAl Viro return -EPERM; 20301da177e4SLinus Torvalds if (flag & O_TRUNC) 20317715b521SAl Viro return -EPERM; 20321da177e4SLinus Torvalds } 20331da177e4SLinus Torvalds 20341da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 20352e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 20367715b521SAl Viro return -EPERM; 20371da177e4SLinus Torvalds 2038f3c7691eSJ. Bruce Fields return 0; 20397715b521SAl Viro } 20407715b521SAl Viro 2041e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 20427715b521SAl Viro { 2043e1181ee6SJeff Layton struct path *path = &filp->f_path; 20447715b521SAl Viro struct inode *inode = path->dentry->d_inode; 20457715b521SAl Viro int error = get_write_access(inode); 20461da177e4SLinus Torvalds if (error) 20477715b521SAl Viro return error; 20481da177e4SLinus Torvalds /* 20491da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 20501da177e4SLinus Torvalds */ 20511da177e4SLinus Torvalds error = locks_verify_locked(inode); 2052be6d3e56SKentaro Takeda if (!error) 2053ea0d3ab2STetsuo Handa error = security_path_truncate(path); 20541da177e4SLinus Torvalds if (!error) { 20557715b521SAl Viro error = do_truncate(path->dentry, 0, 2056d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2057e1181ee6SJeff Layton filp); 20581da177e4SLinus Torvalds } 20591da177e4SLinus Torvalds put_write_access(inode); 2060acd0c935SMimi Zohar return error; 20611da177e4SLinus Torvalds } 20621da177e4SLinus Torvalds 2063d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2064d57999e1SDave Hansen { 20658a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 20668a5e929dSAl Viro flag--; 2067d57999e1SDave Hansen return flag; 2068d57999e1SDave Hansen } 2069d57999e1SDave Hansen 207031e6b01fSNick Piggin /* 2071fe2d35ffSAl Viro * Handle the last step of open() 207231e6b01fSNick Piggin */ 2073fb1cc555SAl Viro static struct file *do_last(struct nameidata *nd, struct path *path, 2074c3e380b0SAl Viro const struct open_flags *op, const char *pathname) 2075fb1cc555SAl Viro { 2076a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 20776c0d46c4SAl Viro struct dentry *dentry; 2078ca344a89SAl Viro int open_flag = op->open_flag; 20796c0d46c4SAl Viro int will_truncate = open_flag & O_TRUNC; 2080ca344a89SAl Viro int want_write = 0; 2081bcda7652SAl Viro int acc_mode = op->acc_mode; 2082fb1cc555SAl Viro struct file *filp; 208316c2cd71SAl Viro int error; 2084fb1cc555SAl Viro 2085c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2086c3e380b0SAl Viro nd->flags |= op->intent; 2087c3e380b0SAl Viro 20881f36f774SAl Viro switch (nd->last_type) { 20891f36f774SAl Viro case LAST_DOTDOT: 2090176306f5SNeil Brown case LAST_DOT: 2091fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2092fe2d35ffSAl Viro if (error) 2093fe2d35ffSAl Viro return ERR_PTR(error); 20941f36f774SAl Viro /* fallthrough */ 20951f36f774SAl Viro case LAST_ROOT: 20969f1fafeeSAl Viro error = complete_walk(nd); 209716c2cd71SAl Viro if (error) 20989f1fafeeSAl Viro return ERR_PTR(error); 2099fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2100ca344a89SAl Viro if (open_flag & O_CREAT) { 210116c2cd71SAl Viro error = -EISDIR; 21021f36f774SAl Viro goto exit; 2103fe2d35ffSAl Viro } 2104fe2d35ffSAl Viro goto ok; 21051f36f774SAl Viro case LAST_BIND: 21069f1fafeeSAl Viro error = complete_walk(nd); 210716c2cd71SAl Viro if (error) 21089f1fafeeSAl Viro return ERR_PTR(error); 21091f36f774SAl Viro audit_inode(pathname, dir); 21101f36f774SAl Viro goto ok; 21111f36f774SAl Viro } 2112a2c36b45SAl Viro 2113ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2114bcda7652SAl Viro int symlink_ok = 0; 2115fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2116fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2117bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 2118bcda7652SAl Viro symlink_ok = 1; 2119fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2120ce57dfc1SAl Viro error = walk_component(nd, path, &nd->last, LAST_NORM, 2121ce57dfc1SAl Viro !symlink_ok); 2122ce57dfc1SAl Viro if (error < 0) 2123fe2d35ffSAl Viro return ERR_PTR(error); 2124ce57dfc1SAl Viro if (error) /* symlink */ 2125fe2d35ffSAl Viro return NULL; 2126fe2d35ffSAl Viro /* sayonara */ 21279f1fafeeSAl Viro error = complete_walk(nd); 21289f1fafeeSAl Viro if (error) 2129fe2d35ffSAl Viro return ERR_PTR(-ECHILD); 2130fe2d35ffSAl Viro 2131fe2d35ffSAl Viro error = -ENOTDIR; 2132fe2d35ffSAl Viro if (nd->flags & LOOKUP_DIRECTORY) { 2133ce57dfc1SAl Viro if (!nd->inode->i_op->lookup) 2134fe2d35ffSAl Viro goto exit; 2135fe2d35ffSAl Viro } 2136fe2d35ffSAl Viro audit_inode(pathname, nd->path.dentry); 2137fe2d35ffSAl Viro goto ok; 2138fe2d35ffSAl Viro } 2139fe2d35ffSAl Viro 2140fe2d35ffSAl Viro /* create side of things */ 21419f1fafeeSAl Viro error = complete_walk(nd); 21429f1fafeeSAl Viro if (error) 21439f1fafeeSAl Viro return ERR_PTR(error); 2144fe2d35ffSAl Viro 2145fe2d35ffSAl Viro audit_inode(pathname, dir); 214616c2cd71SAl Viro error = -EISDIR; 21471f36f774SAl Viro /* trailing slashes? */ 214831e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 21491f36f774SAl Viro goto exit; 21501f36f774SAl Viro 2151a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 2152a1e28038SAl Viro 21536c0d46c4SAl Viro dentry = lookup_hash(nd); 21546c0d46c4SAl Viro error = PTR_ERR(dentry); 21556c0d46c4SAl Viro if (IS_ERR(dentry)) { 2156fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2157fb1cc555SAl Viro goto exit; 2158fb1cc555SAl Viro } 2159fb1cc555SAl Viro 21606c0d46c4SAl Viro path->dentry = dentry; 21616c0d46c4SAl Viro path->mnt = nd->path.mnt; 21626c0d46c4SAl Viro 2163fb1cc555SAl Viro /* Negative dentry, just create the file */ 21646c0d46c4SAl Viro if (!dentry->d_inode) { 21656c0d46c4SAl Viro int mode = op->mode; 21666c0d46c4SAl Viro if (!IS_POSIXACL(dir->d_inode)) 21676c0d46c4SAl Viro mode &= ~current_umask(); 2168fb1cc555SAl Viro /* 2169fb1cc555SAl Viro * This write is needed to ensure that a 21706c0d46c4SAl Viro * rw->ro transition does not occur between 2171fb1cc555SAl Viro * the time when the file is created and when 2172fb1cc555SAl Viro * a permanent write count is taken through 2173fb1cc555SAl Viro * the 'struct file' in nameidata_to_filp(). 2174fb1cc555SAl Viro */ 2175fb1cc555SAl Viro error = mnt_want_write(nd->path.mnt); 2176fb1cc555SAl Viro if (error) 2177fb1cc555SAl Viro goto exit_mutex_unlock; 2178ca344a89SAl Viro want_write = 1; 21799b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2180ca344a89SAl Viro open_flag &= ~O_TRUNC; 21816c0d46c4SAl Viro will_truncate = 0; 2182bcda7652SAl Viro acc_mode = MAY_OPEN; 21836c0d46c4SAl Viro error = security_path_mknod(&nd->path, dentry, mode, 0); 21846c0d46c4SAl Viro if (error) 21856c0d46c4SAl Viro goto exit_mutex_unlock; 21866c0d46c4SAl Viro error = vfs_create(dir->d_inode, dentry, mode, nd); 21876c0d46c4SAl Viro if (error) 21886c0d46c4SAl Viro goto exit_mutex_unlock; 21896c0d46c4SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 21906c0d46c4SAl Viro dput(nd->path.dentry); 21916c0d46c4SAl Viro nd->path.dentry = dentry; 2192ca344a89SAl Viro goto common; 2193fb1cc555SAl Viro } 2194fb1cc555SAl Viro 2195fb1cc555SAl Viro /* 2196fb1cc555SAl Viro * It already exists. 2197fb1cc555SAl Viro */ 2198fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2199fb1cc555SAl Viro audit_inode(pathname, path->dentry); 2200fb1cc555SAl Viro 2201fb1cc555SAl Viro error = -EEXIST; 2202ca344a89SAl Viro if (open_flag & O_EXCL) 2203fb1cc555SAl Viro goto exit_dput; 2204fb1cc555SAl Viro 22059875cf80SDavid Howells error = follow_managed(path, nd->flags); 22069875cf80SDavid Howells if (error < 0) 2207fb1cc555SAl Viro goto exit_dput; 2208fb1cc555SAl Viro 2209fb1cc555SAl Viro error = -ENOENT; 2210fb1cc555SAl Viro if (!path->dentry->d_inode) 2211fb1cc555SAl Viro goto exit_dput; 22129e67f361SAl Viro 22139e67f361SAl Viro if (path->dentry->d_inode->i_op->follow_link) 2214fb1cc555SAl Viro return NULL; 2215fb1cc555SAl Viro 2216fb1cc555SAl Viro path_to_nameidata(path, nd); 221731e6b01fSNick Piggin nd->inode = path->dentry->d_inode; 2218fb1cc555SAl Viro error = -EISDIR; 221931e6b01fSNick Piggin if (S_ISDIR(nd->inode->i_mode)) 2220fb1cc555SAl Viro goto exit; 222167ee3ad2SAl Viro ok: 22226c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 22236c0d46c4SAl Viro will_truncate = 0; 22246c0d46c4SAl Viro 22250f9d1a10SAl Viro if (will_truncate) { 22260f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 22270f9d1a10SAl Viro if (error) 22280f9d1a10SAl Viro goto exit; 2229ca344a89SAl Viro want_write = 1; 22300f9d1a10SAl Viro } 2231ca344a89SAl Viro common: 2232bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 2233ca344a89SAl Viro if (error) 22340f9d1a10SAl Viro goto exit; 22350f9d1a10SAl Viro filp = nameidata_to_filp(nd); 22360f9d1a10SAl Viro if (!IS_ERR(filp)) { 22370f9d1a10SAl Viro error = ima_file_check(filp, op->acc_mode); 22380f9d1a10SAl Viro if (error) { 22390f9d1a10SAl Viro fput(filp); 22400f9d1a10SAl Viro filp = ERR_PTR(error); 22410f9d1a10SAl Viro } 22420f9d1a10SAl Viro } 22430f9d1a10SAl Viro if (!IS_ERR(filp)) { 22440f9d1a10SAl Viro if (will_truncate) { 22450f9d1a10SAl Viro error = handle_truncate(filp); 22460f9d1a10SAl Viro if (error) { 22470f9d1a10SAl Viro fput(filp); 22480f9d1a10SAl Viro filp = ERR_PTR(error); 22490f9d1a10SAl Viro } 22500f9d1a10SAl Viro } 22510f9d1a10SAl Viro } 2252ca344a89SAl Viro out: 2253ca344a89SAl Viro if (want_write) 22540f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 22550f9d1a10SAl Viro path_put(&nd->path); 2256fb1cc555SAl Viro return filp; 2257fb1cc555SAl Viro 2258fb1cc555SAl Viro exit_mutex_unlock: 2259fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2260fb1cc555SAl Viro exit_dput: 2261fb1cc555SAl Viro path_put_conditional(path, nd); 2262fb1cc555SAl Viro exit: 2263ca344a89SAl Viro filp = ERR_PTR(error); 2264ca344a89SAl Viro goto out; 2265fb1cc555SAl Viro } 2266fb1cc555SAl Viro 226713aab428SAl Viro static struct file *path_openat(int dfd, const char *pathname, 226873d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 22691da177e4SLinus Torvalds { 2270fe2d35ffSAl Viro struct file *base = NULL; 22714a3fd211SDave Hansen struct file *filp; 22729850c056SAl Viro struct path path; 227313aab428SAl Viro int error; 227431e6b01fSNick Piggin 227531e6b01fSNick Piggin filp = get_empty_filp(); 227631e6b01fSNick Piggin if (!filp) 227731e6b01fSNick Piggin return ERR_PTR(-ENFILE); 227831e6b01fSNick Piggin 227947c805dcSAl Viro filp->f_flags = op->open_flag; 228073d049a4SAl Viro nd->intent.open.file = filp; 228173d049a4SAl Viro nd->intent.open.flags = open_to_namei_flags(op->open_flag); 228273d049a4SAl Viro nd->intent.open.create_mode = op->mode; 228331e6b01fSNick Piggin 228473d049a4SAl Viro error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); 228531e6b01fSNick Piggin if (unlikely(error)) 228613aab428SAl Viro goto out_filp; 228731e6b01fSNick Piggin 2288fe2d35ffSAl Viro current->total_link_count = 0; 228973d049a4SAl Viro error = link_path_walk(pathname, nd); 229031e6b01fSNick Piggin if (unlikely(error)) 229131e6b01fSNick Piggin goto out_filp; 22921da177e4SLinus Torvalds 229373d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2294806b681cSAl Viro while (unlikely(!filp)) { /* trailing symlink */ 22957b9337aaSNick Piggin struct path link = path; 2296def4af30SAl Viro void *cookie; 2297574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 229873d049a4SAl Viro path_put_conditional(&path, nd); 229973d049a4SAl Viro path_put(&nd->path); 230040b39136SAl Viro filp = ERR_PTR(-ELOOP); 230140b39136SAl Viro break; 230240b39136SAl Viro } 230373d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 230473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 2305574197e0SAl Viro error = follow_link(&link, nd, &cookie); 2306c3e380b0SAl Viro if (unlikely(error)) 2307f1afe9efSAl Viro filp = ERR_PTR(error); 2308c3e380b0SAl Viro else 230973d049a4SAl Viro filp = do_last(nd, &path, op, pathname); 2310574197e0SAl Viro put_link(nd, &link, cookie); 2311806b681cSAl Viro } 231210fa8e62SAl Viro out: 231373d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 231473d049a4SAl Viro path_put(&nd->root); 2315fe2d35ffSAl Viro if (base) 2316fe2d35ffSAl Viro fput(base); 231773d049a4SAl Viro release_open_intent(nd); 231810fa8e62SAl Viro return filp; 23191da177e4SLinus Torvalds 232031e6b01fSNick Piggin out_filp: 232110fa8e62SAl Viro filp = ERR_PTR(error); 232210fa8e62SAl Viro goto out; 2323de459215SKirill Korotaev } 23241da177e4SLinus Torvalds 232513aab428SAl Viro struct file *do_filp_open(int dfd, const char *pathname, 232613aab428SAl Viro const struct open_flags *op, int flags) 232713aab428SAl Viro { 232873d049a4SAl Viro struct nameidata nd; 232913aab428SAl Viro struct file *filp; 233013aab428SAl Viro 233173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 233213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 233373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 233413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 233573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 233613aab428SAl Viro return filp; 233713aab428SAl Viro } 233813aab428SAl Viro 233973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 234073d049a4SAl Viro const char *name, const struct open_flags *op, int flags) 234173d049a4SAl Viro { 234273d049a4SAl Viro struct nameidata nd; 234373d049a4SAl Viro struct file *file; 234473d049a4SAl Viro 234573d049a4SAl Viro nd.root.mnt = mnt; 234673d049a4SAl Viro nd.root.dentry = dentry; 234773d049a4SAl Viro 234873d049a4SAl Viro flags |= LOOKUP_ROOT; 234973d049a4SAl Viro 2350bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 235173d049a4SAl Viro return ERR_PTR(-ELOOP); 235273d049a4SAl Viro 235373d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); 235473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 235573d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags); 235673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 235773d049a4SAl Viro file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); 235873d049a4SAl Viro return file; 235973d049a4SAl Viro } 236073d049a4SAl Viro 2361ed75e95dSAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) 23621da177e4SLinus Torvalds { 2363c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 2364ed75e95dSAl Viro struct nameidata nd; 2365ed75e95dSAl Viro int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); 2366ed75e95dSAl Viro if (error) 2367ed75e95dSAl Viro return ERR_PTR(error); 23681da177e4SLinus Torvalds 2369c663e5d8SChristoph Hellwig /* 2370c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 2371c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 2372c663e5d8SChristoph Hellwig */ 2373ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 2374ed75e95dSAl Viro goto out; 2375ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 2376ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 2377ed75e95dSAl Viro nd.intent.open.flags = O_EXCL; 2378c663e5d8SChristoph Hellwig 2379c663e5d8SChristoph Hellwig /* 2380c663e5d8SChristoph Hellwig * Do the final lookup. 2381c663e5d8SChristoph Hellwig */ 2382ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 2383ed75e95dSAl Viro dentry = lookup_hash(&nd); 23841da177e4SLinus Torvalds if (IS_ERR(dentry)) 23851da177e4SLinus Torvalds goto fail; 2386c663e5d8SChristoph Hellwig 2387e9baf6e5SAl Viro if (dentry->d_inode) 2388e9baf6e5SAl Viro goto eexist; 2389c663e5d8SChristoph Hellwig /* 2390c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 2391c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 2392c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 2393c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 2394c663e5d8SChristoph Hellwig */ 2395ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 23961da177e4SLinus Torvalds dput(dentry); 23971da177e4SLinus Torvalds dentry = ERR_PTR(-ENOENT); 2398ed75e95dSAl Viro goto fail; 2399e9baf6e5SAl Viro } 2400ed75e95dSAl Viro *path = nd.path; 2401e9baf6e5SAl Viro return dentry; 2402e9baf6e5SAl Viro eexist: 2403e9baf6e5SAl Viro dput(dentry); 2404e9baf6e5SAl Viro dentry = ERR_PTR(-EEXIST); 24051da177e4SLinus Torvalds fail: 2406dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 2407ed75e95dSAl Viro out: 2408dae6ad8fSAl Viro path_put(&nd.path); 2409ed75e95dSAl Viro return dentry; 2410dae6ad8fSAl Viro } 2411dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 2412dae6ad8fSAl Viro 2413dae6ad8fSAl Viro struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) 2414dae6ad8fSAl Viro { 2415dae6ad8fSAl Viro char *tmp = getname(pathname); 2416dae6ad8fSAl Viro struct dentry *res; 2417dae6ad8fSAl Viro if (IS_ERR(tmp)) 2418dae6ad8fSAl Viro return ERR_CAST(tmp); 2419dae6ad8fSAl Viro res = kern_path_create(dfd, tmp, path, is_dir); 2420dae6ad8fSAl Viro putname(tmp); 2421dae6ad8fSAl Viro return res; 2422dae6ad8fSAl Viro } 2423dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 2424dae6ad8fSAl Viro 24251da177e4SLinus Torvalds int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 24261da177e4SLinus Torvalds { 2427a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 24281da177e4SLinus Torvalds 24291da177e4SLinus Torvalds if (error) 24301da177e4SLinus Torvalds return error; 24311da177e4SLinus Torvalds 2432e795b717SSerge E. Hallyn if ((S_ISCHR(mode) || S_ISBLK(mode)) && 2433e795b717SSerge E. Hallyn !ns_capable(inode_userns(dir), CAP_MKNOD)) 24341da177e4SLinus Torvalds return -EPERM; 24351da177e4SLinus Torvalds 2436acfa4380SAl Viro if (!dir->i_op->mknod) 24371da177e4SLinus Torvalds return -EPERM; 24381da177e4SLinus Torvalds 243908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 244008ce5f16SSerge E. Hallyn if (error) 244108ce5f16SSerge E. Hallyn return error; 244208ce5f16SSerge E. Hallyn 24431da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 24441da177e4SLinus Torvalds if (error) 24451da177e4SLinus Torvalds return error; 24461da177e4SLinus Torvalds 24471da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 2448a74574aaSStephen Smalley if (!error) 2449f38aa942SAmy Griffis fsnotify_create(dir, dentry); 24501da177e4SLinus Torvalds return error; 24511da177e4SLinus Torvalds } 24521da177e4SLinus Torvalds 2453463c3197SDave Hansen static int may_mknod(mode_t mode) 2454463c3197SDave Hansen { 2455463c3197SDave Hansen switch (mode & S_IFMT) { 2456463c3197SDave Hansen case S_IFREG: 2457463c3197SDave Hansen case S_IFCHR: 2458463c3197SDave Hansen case S_IFBLK: 2459463c3197SDave Hansen case S_IFIFO: 2460463c3197SDave Hansen case S_IFSOCK: 2461463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 2462463c3197SDave Hansen return 0; 2463463c3197SDave Hansen case S_IFDIR: 2464463c3197SDave Hansen return -EPERM; 2465463c3197SDave Hansen default: 2466463c3197SDave Hansen return -EINVAL; 2467463c3197SDave Hansen } 2468463c3197SDave Hansen } 2469463c3197SDave Hansen 24702e4d0924SHeiko Carstens SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, 24712e4d0924SHeiko Carstens unsigned, dev) 24721da177e4SLinus Torvalds { 24731da177e4SLinus Torvalds struct dentry *dentry; 2474dae6ad8fSAl Viro struct path path; 2475dae6ad8fSAl Viro int error; 24761da177e4SLinus Torvalds 24771da177e4SLinus Torvalds if (S_ISDIR(mode)) 24781da177e4SLinus Torvalds return -EPERM; 24791da177e4SLinus Torvalds 2480dae6ad8fSAl Viro dentry = user_path_create(dfd, filename, &path, 0); 2481dae6ad8fSAl Viro if (IS_ERR(dentry)) 2482dae6ad8fSAl Viro return PTR_ERR(dentry); 24832ad94ae6SAl Viro 2484dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2485ce3b0f8dSAl Viro mode &= ~current_umask(); 2486463c3197SDave Hansen error = may_mknod(mode); 2487463c3197SDave Hansen if (error) 2488463c3197SDave Hansen goto out_dput; 2489dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2490463c3197SDave Hansen if (error) 2491463c3197SDave Hansen goto out_dput; 2492dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 2493be6d3e56SKentaro Takeda if (error) 2494be6d3e56SKentaro Takeda goto out_drop_write; 24951da177e4SLinus Torvalds switch (mode & S_IFMT) { 24961da177e4SLinus Torvalds case 0: case S_IFREG: 2497dae6ad8fSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); 24981da177e4SLinus Torvalds break; 24991da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 2500dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 25011da177e4SLinus Torvalds new_decode_dev(dev)); 25021da177e4SLinus Torvalds break; 25031da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 2504dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 25051da177e4SLinus Torvalds break; 25061da177e4SLinus Torvalds } 2507be6d3e56SKentaro Takeda out_drop_write: 2508dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2509463c3197SDave Hansen out_dput: 25101da177e4SLinus Torvalds dput(dentry); 2511dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2512dae6ad8fSAl Viro path_put(&path); 25131da177e4SLinus Torvalds 25141da177e4SLinus Torvalds return error; 25151da177e4SLinus Torvalds } 25161da177e4SLinus Torvalds 25173480b257SHeiko Carstens SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) 25185590ff0dSUlrich Drepper { 25195590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 25205590ff0dSUlrich Drepper } 25215590ff0dSUlrich Drepper 25221da177e4SLinus Torvalds int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) 25231da177e4SLinus Torvalds { 2524a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25251da177e4SLinus Torvalds 25261da177e4SLinus Torvalds if (error) 25271da177e4SLinus Torvalds return error; 25281da177e4SLinus Torvalds 2529acfa4380SAl Viro if (!dir->i_op->mkdir) 25301da177e4SLinus Torvalds return -EPERM; 25311da177e4SLinus Torvalds 25321da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 25331da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 25341da177e4SLinus Torvalds if (error) 25351da177e4SLinus Torvalds return error; 25361da177e4SLinus Torvalds 25371da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 2538a74574aaSStephen Smalley if (!error) 2539f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 25401da177e4SLinus Torvalds return error; 25411da177e4SLinus Torvalds } 25421da177e4SLinus Torvalds 25432e4d0924SHeiko Carstens SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) 25441da177e4SLinus Torvalds { 25456902d925SDave Hansen struct dentry *dentry; 2546dae6ad8fSAl Viro struct path path; 2547dae6ad8fSAl Viro int error; 25481da177e4SLinus Torvalds 2549dae6ad8fSAl Viro dentry = user_path_create(dfd, pathname, &path, 1); 25506902d925SDave Hansen if (IS_ERR(dentry)) 2551dae6ad8fSAl Viro return PTR_ERR(dentry); 25526902d925SDave Hansen 2553dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 2554ce3b0f8dSAl Viro mode &= ~current_umask(); 2555dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 2556463c3197SDave Hansen if (error) 2557463c3197SDave Hansen goto out_dput; 2558dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 2559be6d3e56SKentaro Takeda if (error) 2560be6d3e56SKentaro Takeda goto out_drop_write; 2561dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 2562be6d3e56SKentaro Takeda out_drop_write: 2563dae6ad8fSAl Viro mnt_drop_write(path.mnt); 2564463c3197SDave Hansen out_dput: 25651da177e4SLinus Torvalds dput(dentry); 2566dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2567dae6ad8fSAl Viro path_put(&path); 25681da177e4SLinus Torvalds return error; 25691da177e4SLinus Torvalds } 25701da177e4SLinus Torvalds 25713cdad428SHeiko Carstens SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) 25725590ff0dSUlrich Drepper { 25735590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 25745590ff0dSUlrich Drepper } 25755590ff0dSUlrich Drepper 25761da177e4SLinus Torvalds /* 2577a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 2578a71905f0SSage Weil * should have a usage count of 2 if we're the only user of this 2579a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 2580a71905f0SSage Weil * then we drop the dentry now. 25811da177e4SLinus Torvalds * 25821da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 25831da177e4SLinus Torvalds * do a 25841da177e4SLinus Torvalds * 25851da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 25861da177e4SLinus Torvalds * return -EBUSY; 25871da177e4SLinus Torvalds * 25881da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 25891da177e4SLinus Torvalds * that is still in use by something else.. 25901da177e4SLinus Torvalds */ 25911da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 25921da177e4SLinus Torvalds { 25931da177e4SLinus Torvalds shrink_dcache_parent(dentry); 25941da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 259564252c75SSage Weil if (dentry->d_count == 1) 25961da177e4SLinus Torvalds __d_drop(dentry); 25971da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 25981da177e4SLinus Torvalds } 25991da177e4SLinus Torvalds 26001da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 26011da177e4SLinus Torvalds { 26021da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 26031da177e4SLinus Torvalds 26041da177e4SLinus Torvalds if (error) 26051da177e4SLinus Torvalds return error; 26061da177e4SLinus Torvalds 2607acfa4380SAl Viro if (!dir->i_op->rmdir) 26081da177e4SLinus Torvalds return -EPERM; 26091da177e4SLinus Torvalds 26101d2ef590SAl Viro dget(dentry); 26111b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 2612912dbc15SSage Weil 26131da177e4SLinus Torvalds error = -EBUSY; 2614912dbc15SSage Weil if (d_mountpoint(dentry)) 2615912dbc15SSage Weil goto out; 2616912dbc15SSage Weil 26171da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 2618912dbc15SSage Weil if (error) 2619912dbc15SSage Weil goto out; 2620912dbc15SSage Weil 26213cebde24SSage Weil shrink_dcache_parent(dentry); 26221da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 2623912dbc15SSage Weil if (error) 2624912dbc15SSage Weil goto out; 2625912dbc15SSage Weil 26261da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 2627d83c49f3SAl Viro dont_mount(dentry); 26281da177e4SLinus Torvalds 2629912dbc15SSage Weil out: 2630912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 26311d2ef590SAl Viro dput(dentry); 2632912dbc15SSage Weil if (!error) 2633912dbc15SSage Weil d_delete(dentry); 26341da177e4SLinus Torvalds return error; 26351da177e4SLinus Torvalds } 26361da177e4SLinus Torvalds 26375590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 26381da177e4SLinus Torvalds { 26391da177e4SLinus Torvalds int error = 0; 26401da177e4SLinus Torvalds char * name; 26411da177e4SLinus Torvalds struct dentry *dentry; 26421da177e4SLinus Torvalds struct nameidata nd; 26431da177e4SLinus Torvalds 26442ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 26451da177e4SLinus Torvalds if (error) 26462ad94ae6SAl Viro return error; 26471da177e4SLinus Torvalds 26481da177e4SLinus Torvalds switch(nd.last_type) { 26491da177e4SLinus Torvalds case LAST_DOTDOT: 26501da177e4SLinus Torvalds error = -ENOTEMPTY; 26511da177e4SLinus Torvalds goto exit1; 26521da177e4SLinus Torvalds case LAST_DOT: 26531da177e4SLinus Torvalds error = -EINVAL; 26541da177e4SLinus Torvalds goto exit1; 26551da177e4SLinus Torvalds case LAST_ROOT: 26561da177e4SLinus Torvalds error = -EBUSY; 26571da177e4SLinus Torvalds goto exit1; 26581da177e4SLinus Torvalds } 26590612d9fbSOGAWA Hirofumi 26600612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 26610612d9fbSOGAWA Hirofumi 26624ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 266349705b77SChristoph Hellwig dentry = lookup_hash(&nd); 26641da177e4SLinus Torvalds error = PTR_ERR(dentry); 26656902d925SDave Hansen if (IS_ERR(dentry)) 26666902d925SDave Hansen goto exit2; 2667e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 2668e6bc45d6STheodore Ts'o error = -ENOENT; 2669e6bc45d6STheodore Ts'o goto exit3; 2670e6bc45d6STheodore Ts'o } 26710622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 26720622753bSDave Hansen if (error) 26730622753bSDave Hansen goto exit3; 2674be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 2675be6d3e56SKentaro Takeda if (error) 2676be6d3e56SKentaro Takeda goto exit4; 26774ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 2678be6d3e56SKentaro Takeda exit4: 26790622753bSDave Hansen mnt_drop_write(nd.path.mnt); 26800622753bSDave Hansen exit3: 26811da177e4SLinus Torvalds dput(dentry); 26826902d925SDave Hansen exit2: 26834ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 26841da177e4SLinus Torvalds exit1: 26851d957f9bSJan Blunck path_put(&nd.path); 26861da177e4SLinus Torvalds putname(name); 26871da177e4SLinus Torvalds return error; 26881da177e4SLinus Torvalds } 26891da177e4SLinus Torvalds 26903cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 26915590ff0dSUlrich Drepper { 26925590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 26935590ff0dSUlrich Drepper } 26945590ff0dSUlrich Drepper 26951da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 26961da177e4SLinus Torvalds { 26971da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 26981da177e4SLinus Torvalds 26991da177e4SLinus Torvalds if (error) 27001da177e4SLinus Torvalds return error; 27011da177e4SLinus Torvalds 2702acfa4380SAl Viro if (!dir->i_op->unlink) 27031da177e4SLinus Torvalds return -EPERM; 27041da177e4SLinus Torvalds 27051b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 27061da177e4SLinus Torvalds if (d_mountpoint(dentry)) 27071da177e4SLinus Torvalds error = -EBUSY; 27081da177e4SLinus Torvalds else { 27091da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 2710bec1052eSAl Viro if (!error) { 27111da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 2712bec1052eSAl Viro if (!error) 2713d83c49f3SAl Viro dont_mount(dentry); 2714bec1052eSAl Viro } 27151da177e4SLinus Torvalds } 27161b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 27171da177e4SLinus Torvalds 27181da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 27191da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 2720ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 27211da177e4SLinus Torvalds d_delete(dentry); 27221da177e4SLinus Torvalds } 27230eeca283SRobert Love 27241da177e4SLinus Torvalds return error; 27251da177e4SLinus Torvalds } 27261da177e4SLinus Torvalds 27271da177e4SLinus Torvalds /* 27281da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 27291b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 27301da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 27311da177e4SLinus Torvalds * while waiting on the I/O. 27321da177e4SLinus Torvalds */ 27335590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 27341da177e4SLinus Torvalds { 27352ad94ae6SAl Viro int error; 27361da177e4SLinus Torvalds char *name; 27371da177e4SLinus Torvalds struct dentry *dentry; 27381da177e4SLinus Torvalds struct nameidata nd; 27391da177e4SLinus Torvalds struct inode *inode = NULL; 27401da177e4SLinus Torvalds 27412ad94ae6SAl Viro error = user_path_parent(dfd, pathname, &nd, &name); 27421da177e4SLinus Torvalds if (error) 27432ad94ae6SAl Viro return error; 27442ad94ae6SAl Viro 27451da177e4SLinus Torvalds error = -EISDIR; 27461da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 27471da177e4SLinus Torvalds goto exit1; 27480612d9fbSOGAWA Hirofumi 27490612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 27500612d9fbSOGAWA Hirofumi 27514ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 275249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 27531da177e4SLinus Torvalds error = PTR_ERR(dentry); 27541da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 27551da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 275650338b88STörök Edwin if (nd.last.name[nd.last.len]) 275750338b88STörök Edwin goto slashes; 27581da177e4SLinus Torvalds inode = dentry->d_inode; 275950338b88STörök Edwin if (!inode) 2760e6bc45d6STheodore Ts'o goto slashes; 27617de9c6eeSAl Viro ihold(inode); 27620622753bSDave Hansen error = mnt_want_write(nd.path.mnt); 27630622753bSDave Hansen if (error) 27640622753bSDave Hansen goto exit2; 2765be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 2766be6d3e56SKentaro Takeda if (error) 2767be6d3e56SKentaro Takeda goto exit3; 27684ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 2769be6d3e56SKentaro Takeda exit3: 27700622753bSDave Hansen mnt_drop_write(nd.path.mnt); 27711da177e4SLinus Torvalds exit2: 27721da177e4SLinus Torvalds dput(dentry); 27731da177e4SLinus Torvalds } 27744ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 27751da177e4SLinus Torvalds if (inode) 27761da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 27771da177e4SLinus Torvalds exit1: 27781d957f9bSJan Blunck path_put(&nd.path); 27791da177e4SLinus Torvalds putname(name); 27801da177e4SLinus Torvalds return error; 27811da177e4SLinus Torvalds 27821da177e4SLinus Torvalds slashes: 27831da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 27841da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 27851da177e4SLinus Torvalds goto exit2; 27861da177e4SLinus Torvalds } 27871da177e4SLinus Torvalds 27882e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 27895590ff0dSUlrich Drepper { 27905590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 27915590ff0dSUlrich Drepper return -EINVAL; 27925590ff0dSUlrich Drepper 27935590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 27945590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 27955590ff0dSUlrich Drepper 27965590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 27975590ff0dSUlrich Drepper } 27985590ff0dSUlrich Drepper 27993480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 28005590ff0dSUlrich Drepper { 28015590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 28025590ff0dSUlrich Drepper } 28035590ff0dSUlrich Drepper 2804db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 28051da177e4SLinus Torvalds { 2806a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28071da177e4SLinus Torvalds 28081da177e4SLinus Torvalds if (error) 28091da177e4SLinus Torvalds return error; 28101da177e4SLinus Torvalds 2811acfa4380SAl Viro if (!dir->i_op->symlink) 28121da177e4SLinus Torvalds return -EPERM; 28131da177e4SLinus Torvalds 28141da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 28151da177e4SLinus Torvalds if (error) 28161da177e4SLinus Torvalds return error; 28171da177e4SLinus Torvalds 28181da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 2819a74574aaSStephen Smalley if (!error) 2820f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28211da177e4SLinus Torvalds return error; 28221da177e4SLinus Torvalds } 28231da177e4SLinus Torvalds 28242e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 28252e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 28261da177e4SLinus Torvalds { 28272ad94ae6SAl Viro int error; 28281da177e4SLinus Torvalds char *from; 28296902d925SDave Hansen struct dentry *dentry; 2830dae6ad8fSAl Viro struct path path; 28311da177e4SLinus Torvalds 28321da177e4SLinus Torvalds from = getname(oldname); 28331da177e4SLinus Torvalds if (IS_ERR(from)) 28341da177e4SLinus Torvalds return PTR_ERR(from); 28352ad94ae6SAl Viro 2836dae6ad8fSAl Viro dentry = user_path_create(newdfd, newname, &path, 0); 28371da177e4SLinus Torvalds error = PTR_ERR(dentry); 28386902d925SDave Hansen if (IS_ERR(dentry)) 2839dae6ad8fSAl Viro goto out_putname; 28406902d925SDave Hansen 2841dae6ad8fSAl Viro error = mnt_want_write(path.mnt); 284275c3f29dSDave Hansen if (error) 284375c3f29dSDave Hansen goto out_dput; 2844dae6ad8fSAl Viro error = security_path_symlink(&path, dentry, from); 2845be6d3e56SKentaro Takeda if (error) 2846be6d3e56SKentaro Takeda goto out_drop_write; 2847dae6ad8fSAl Viro error = vfs_symlink(path.dentry->d_inode, dentry, from); 2848be6d3e56SKentaro Takeda out_drop_write: 2849dae6ad8fSAl Viro mnt_drop_write(path.mnt); 285075c3f29dSDave Hansen out_dput: 28511da177e4SLinus Torvalds dput(dentry); 2852dae6ad8fSAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 2853dae6ad8fSAl Viro path_put(&path); 28546902d925SDave Hansen out_putname: 28551da177e4SLinus Torvalds putname(from); 28561da177e4SLinus Torvalds return error; 28571da177e4SLinus Torvalds } 28581da177e4SLinus Torvalds 28593480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 28605590ff0dSUlrich Drepper { 28615590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 28625590ff0dSUlrich Drepper } 28635590ff0dSUlrich Drepper 28641da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 28651da177e4SLinus Torvalds { 28661da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 28671da177e4SLinus Torvalds int error; 28681da177e4SLinus Torvalds 28691da177e4SLinus Torvalds if (!inode) 28701da177e4SLinus Torvalds return -ENOENT; 28711da177e4SLinus Torvalds 2872a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 28731da177e4SLinus Torvalds if (error) 28741da177e4SLinus Torvalds return error; 28751da177e4SLinus Torvalds 28761da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 28771da177e4SLinus Torvalds return -EXDEV; 28781da177e4SLinus Torvalds 28791da177e4SLinus Torvalds /* 28801da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 28811da177e4SLinus Torvalds */ 28821da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 28831da177e4SLinus Torvalds return -EPERM; 2884acfa4380SAl Viro if (!dir->i_op->link) 28851da177e4SLinus Torvalds return -EPERM; 28867e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 28871da177e4SLinus Torvalds return -EPERM; 28881da177e4SLinus Torvalds 28891da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 28901da177e4SLinus Torvalds if (error) 28911da177e4SLinus Torvalds return error; 28921da177e4SLinus Torvalds 28937e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 2894aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 2895aae8a97dSAneesh Kumar K.V if (inode->i_nlink == 0) 2896aae8a97dSAneesh Kumar K.V error = -ENOENT; 2897aae8a97dSAneesh Kumar K.V else 28981da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 28997e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 2900e31e14ecSStephen Smalley if (!error) 29017e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 29021da177e4SLinus Torvalds return error; 29031da177e4SLinus Torvalds } 29041da177e4SLinus Torvalds 29051da177e4SLinus Torvalds /* 29061da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 29071da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 29081da177e4SLinus Torvalds * newname. --KAB 29091da177e4SLinus Torvalds * 29101da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 29111da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 29121da177e4SLinus Torvalds * and other special files. --ADM 29131da177e4SLinus Torvalds */ 29142e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 29152e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 29161da177e4SLinus Torvalds { 29171da177e4SLinus Torvalds struct dentry *new_dentry; 2918dae6ad8fSAl Viro struct path old_path, new_path; 291911a7b371SAneesh Kumar K.V int how = 0; 29201da177e4SLinus Torvalds int error; 29211da177e4SLinus Torvalds 292211a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 2923c04030e1SUlrich Drepper return -EINVAL; 292411a7b371SAneesh Kumar K.V /* 292511a7b371SAneesh Kumar K.V * To use null names we require CAP_DAC_READ_SEARCH 292611a7b371SAneesh Kumar K.V * This ensures that not everyone will be able to create 292711a7b371SAneesh Kumar K.V * handlink using the passed filedescriptor. 292811a7b371SAneesh Kumar K.V */ 292911a7b371SAneesh Kumar K.V if (flags & AT_EMPTY_PATH) { 293011a7b371SAneesh Kumar K.V if (!capable(CAP_DAC_READ_SEARCH)) 293111a7b371SAneesh Kumar K.V return -ENOENT; 293211a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 293311a7b371SAneesh Kumar K.V } 2934c04030e1SUlrich Drepper 293511a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 293611a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 293711a7b371SAneesh Kumar K.V 293811a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 29391da177e4SLinus Torvalds if (error) 29402ad94ae6SAl Viro return error; 29412ad94ae6SAl Viro 2942dae6ad8fSAl Viro new_dentry = user_path_create(newdfd, newname, &new_path, 0); 29431da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 29446902d925SDave Hansen if (IS_ERR(new_dentry)) 2945dae6ad8fSAl Viro goto out; 2946dae6ad8fSAl Viro 2947dae6ad8fSAl Viro error = -EXDEV; 2948dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 2949dae6ad8fSAl Viro goto out_dput; 2950dae6ad8fSAl Viro error = mnt_want_write(new_path.mnt); 295175c3f29dSDave Hansen if (error) 295275c3f29dSDave Hansen goto out_dput; 2953dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 2954be6d3e56SKentaro Takeda if (error) 2955be6d3e56SKentaro Takeda goto out_drop_write; 2956dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 2957be6d3e56SKentaro Takeda out_drop_write: 2958dae6ad8fSAl Viro mnt_drop_write(new_path.mnt); 295975c3f29dSDave Hansen out_dput: 29601da177e4SLinus Torvalds dput(new_dentry); 2961dae6ad8fSAl Viro mutex_unlock(&new_path.dentry->d_inode->i_mutex); 2962dae6ad8fSAl Viro path_put(&new_path); 29631da177e4SLinus Torvalds out: 29642d8f3038SAl Viro path_put(&old_path); 29651da177e4SLinus Torvalds 29661da177e4SLinus Torvalds return error; 29671da177e4SLinus Torvalds } 29681da177e4SLinus Torvalds 29693480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 29705590ff0dSUlrich Drepper { 2971c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 29725590ff0dSUlrich Drepper } 29735590ff0dSUlrich Drepper 29741da177e4SLinus Torvalds /* 29751da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 29761da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 29771da177e4SLinus Torvalds * Problems: 29781da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 29791da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 29801da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 2981a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 29821da177e4SLinus Torvalds * story. 29831da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 29841b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 29851da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 29861da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 2987a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 29881da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 29891da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 29901da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 2991a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 29921da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 29931da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 29941da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 2995e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 29961b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 29971da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 2998c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 29991da177e4SLinus Torvalds * locking]. 30001da177e4SLinus Torvalds */ 300175c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 30021da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30031da177e4SLinus Torvalds { 30041da177e4SLinus Torvalds int error = 0; 30059055cba7SSage Weil struct inode *target = new_dentry->d_inode; 30061da177e4SLinus Torvalds 30071da177e4SLinus Torvalds /* 30081da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 30091da177e4SLinus Torvalds * we'll need to flip '..'. 30101da177e4SLinus Torvalds */ 30111da177e4SLinus Torvalds if (new_dir != old_dir) { 3012f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 30131da177e4SLinus Torvalds if (error) 30141da177e4SLinus Torvalds return error; 30151da177e4SLinus Torvalds } 30161da177e4SLinus Torvalds 30171da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30181da177e4SLinus Torvalds if (error) 30191da177e4SLinus Torvalds return error; 30201da177e4SLinus Torvalds 30211d2ef590SAl Viro dget(new_dentry); 3022d83c49f3SAl Viro if (target) 30231b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 30249055cba7SSage Weil 30251da177e4SLinus Torvalds error = -EBUSY; 30269055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 30279055cba7SSage Weil goto out; 30289055cba7SSage Weil 30293cebde24SSage Weil if (target) 30303cebde24SSage Weil shrink_dcache_parent(new_dentry); 30311da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 30329055cba7SSage Weil if (error) 30339055cba7SSage Weil goto out; 30349055cba7SSage Weil 30351da177e4SLinus Torvalds if (target) { 30361da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3037d83c49f3SAl Viro dont_mount(new_dentry); 3038d83c49f3SAl Viro } 30399055cba7SSage Weil out: 30409055cba7SSage Weil if (target) 30411b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30421d2ef590SAl Viro dput(new_dentry); 3043e31e14ecSStephen Smalley if (!error) 3044349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30451da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 30461da177e4SLinus Torvalds return error; 30471da177e4SLinus Torvalds } 30481da177e4SLinus Torvalds 304975c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 30501da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30511da177e4SLinus Torvalds { 305251892bbbSSage Weil struct inode *target = new_dentry->d_inode; 30531da177e4SLinus Torvalds int error; 30541da177e4SLinus Torvalds 30551da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 30561da177e4SLinus Torvalds if (error) 30571da177e4SLinus Torvalds return error; 30581da177e4SLinus Torvalds 30591da177e4SLinus Torvalds dget(new_dentry); 30601da177e4SLinus Torvalds if (target) 30611b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 306251892bbbSSage Weil 30631da177e4SLinus Torvalds error = -EBUSY; 306451892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 306551892bbbSSage Weil goto out; 306651892bbbSSage Weil 30671da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 306851892bbbSSage Weil if (error) 306951892bbbSSage Weil goto out; 307051892bbbSSage Weil 3071bec1052eSAl Viro if (target) 3072d83c49f3SAl Viro dont_mount(new_dentry); 3073349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 30741da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 307551892bbbSSage Weil out: 30761da177e4SLinus Torvalds if (target) 30771b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 30781da177e4SLinus Torvalds dput(new_dentry); 30791da177e4SLinus Torvalds return error; 30801da177e4SLinus Torvalds } 30811da177e4SLinus Torvalds 30821da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 30831da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 30841da177e4SLinus Torvalds { 30851da177e4SLinus Torvalds int error; 30861da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 308759b0df21SEric Paris const unsigned char *old_name; 30881da177e4SLinus Torvalds 30891da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 30901da177e4SLinus Torvalds return 0; 30911da177e4SLinus Torvalds 30921da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 30931da177e4SLinus Torvalds if (error) 30941da177e4SLinus Torvalds return error; 30951da177e4SLinus Torvalds 30961da177e4SLinus Torvalds if (!new_dentry->d_inode) 3097a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 30981da177e4SLinus Torvalds else 30991da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 31001da177e4SLinus Torvalds if (error) 31011da177e4SLinus Torvalds return error; 31021da177e4SLinus Torvalds 3103acfa4380SAl Viro if (!old_dir->i_op->rename) 31041da177e4SLinus Torvalds return -EPERM; 31051da177e4SLinus Torvalds 31060eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 31070eeca283SRobert Love 31081da177e4SLinus Torvalds if (is_dir) 31091da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 31101da177e4SLinus Torvalds else 31111da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 3112123df294SAl Viro if (!error) 3113123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 31145a190ae6SAl Viro new_dentry->d_inode, old_dentry); 31150eeca283SRobert Love fsnotify_oldname_free(old_name); 31160eeca283SRobert Love 31171da177e4SLinus Torvalds return error; 31181da177e4SLinus Torvalds } 31191da177e4SLinus Torvalds 31202e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 31212e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 31221da177e4SLinus Torvalds { 31231da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 31241da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 31251da177e4SLinus Torvalds struct dentry *trap; 31261da177e4SLinus Torvalds struct nameidata oldnd, newnd; 31272ad94ae6SAl Viro char *from; 31282ad94ae6SAl Viro char *to; 31292ad94ae6SAl Viro int error; 31301da177e4SLinus Torvalds 31312ad94ae6SAl Viro error = user_path_parent(olddfd, oldname, &oldnd, &from); 31321da177e4SLinus Torvalds if (error) 31331da177e4SLinus Torvalds goto exit; 31341da177e4SLinus Torvalds 31352ad94ae6SAl Viro error = user_path_parent(newdfd, newname, &newnd, &to); 31361da177e4SLinus Torvalds if (error) 31371da177e4SLinus Torvalds goto exit1; 31381da177e4SLinus Torvalds 31391da177e4SLinus Torvalds error = -EXDEV; 31404ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 31411da177e4SLinus Torvalds goto exit2; 31421da177e4SLinus Torvalds 31434ac91378SJan Blunck old_dir = oldnd.path.dentry; 31441da177e4SLinus Torvalds error = -EBUSY; 31451da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 31461da177e4SLinus Torvalds goto exit2; 31471da177e4SLinus Torvalds 31484ac91378SJan Blunck new_dir = newnd.path.dentry; 31491da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 31501da177e4SLinus Torvalds goto exit2; 31511da177e4SLinus Torvalds 31520612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 31530612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 31544e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 31550612d9fbSOGAWA Hirofumi 31561da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 31571da177e4SLinus Torvalds 315849705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 31591da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 31601da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 31611da177e4SLinus Torvalds goto exit3; 31621da177e4SLinus Torvalds /* source must exist */ 31631da177e4SLinus Torvalds error = -ENOENT; 31641da177e4SLinus Torvalds if (!old_dentry->d_inode) 31651da177e4SLinus Torvalds goto exit4; 31661da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 31671da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 31681da177e4SLinus Torvalds error = -ENOTDIR; 31691da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 31701da177e4SLinus Torvalds goto exit4; 31711da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 31721da177e4SLinus Torvalds goto exit4; 31731da177e4SLinus Torvalds } 31741da177e4SLinus Torvalds /* source should not be ancestor of target */ 31751da177e4SLinus Torvalds error = -EINVAL; 31761da177e4SLinus Torvalds if (old_dentry == trap) 31771da177e4SLinus Torvalds goto exit4; 317849705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 31791da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 31801da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 31811da177e4SLinus Torvalds goto exit4; 31821da177e4SLinus Torvalds /* target should not be an ancestor of source */ 31831da177e4SLinus Torvalds error = -ENOTEMPTY; 31841da177e4SLinus Torvalds if (new_dentry == trap) 31851da177e4SLinus Torvalds goto exit5; 31861da177e4SLinus Torvalds 31879079b1ebSDave Hansen error = mnt_want_write(oldnd.path.mnt); 31889079b1ebSDave Hansen if (error) 31899079b1ebSDave Hansen goto exit5; 3190be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 3191be6d3e56SKentaro Takeda &newnd.path, new_dentry); 3192be6d3e56SKentaro Takeda if (error) 3193be6d3e56SKentaro Takeda goto exit6; 31941da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 31951da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 3196be6d3e56SKentaro Takeda exit6: 31979079b1ebSDave Hansen mnt_drop_write(oldnd.path.mnt); 31981da177e4SLinus Torvalds exit5: 31991da177e4SLinus Torvalds dput(new_dentry); 32001da177e4SLinus Torvalds exit4: 32011da177e4SLinus Torvalds dput(old_dentry); 32021da177e4SLinus Torvalds exit3: 32031da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 32041da177e4SLinus Torvalds exit2: 32051d957f9bSJan Blunck path_put(&newnd.path); 32062ad94ae6SAl Viro putname(to); 32071da177e4SLinus Torvalds exit1: 32081d957f9bSJan Blunck path_put(&oldnd.path); 32091da177e4SLinus Torvalds putname(from); 32102ad94ae6SAl Viro exit: 32111da177e4SLinus Torvalds return error; 32121da177e4SLinus Torvalds } 32131da177e4SLinus Torvalds 3214a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 32155590ff0dSUlrich Drepper { 32165590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 32175590ff0dSUlrich Drepper } 32185590ff0dSUlrich Drepper 32191da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 32201da177e4SLinus Torvalds { 32211da177e4SLinus Torvalds int len; 32221da177e4SLinus Torvalds 32231da177e4SLinus Torvalds len = PTR_ERR(link); 32241da177e4SLinus Torvalds if (IS_ERR(link)) 32251da177e4SLinus Torvalds goto out; 32261da177e4SLinus Torvalds 32271da177e4SLinus Torvalds len = strlen(link); 32281da177e4SLinus Torvalds if (len > (unsigned) buflen) 32291da177e4SLinus Torvalds len = buflen; 32301da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 32311da177e4SLinus Torvalds len = -EFAULT; 32321da177e4SLinus Torvalds out: 32331da177e4SLinus Torvalds return len; 32341da177e4SLinus Torvalds } 32351da177e4SLinus Torvalds 32361da177e4SLinus Torvalds /* 32371da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 32381da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 32391da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 32401da177e4SLinus Torvalds */ 32411da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32421da177e4SLinus Torvalds { 32431da177e4SLinus Torvalds struct nameidata nd; 3244cc314eefSLinus Torvalds void *cookie; 3245694a1764SMarcin Slusarz int res; 3246cc314eefSLinus Torvalds 32471da177e4SLinus Torvalds nd.depth = 0; 3248cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 3249694a1764SMarcin Slusarz if (IS_ERR(cookie)) 3250694a1764SMarcin Slusarz return PTR_ERR(cookie); 3251694a1764SMarcin Slusarz 3252694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 32531da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 3254cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 3255694a1764SMarcin Slusarz return res; 32561da177e4SLinus Torvalds } 32571da177e4SLinus Torvalds 32581da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 32591da177e4SLinus Torvalds { 32601da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 32611da177e4SLinus Torvalds } 32621da177e4SLinus Torvalds 32631da177e4SLinus Torvalds /* get the link contents into pagecache */ 32641da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 32651da177e4SLinus Torvalds { 3266ebd09abbSDuane Griffin char *kaddr; 32671da177e4SLinus Torvalds struct page *page; 32681da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 3269090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 32701da177e4SLinus Torvalds if (IS_ERR(page)) 32716fe6900eSNick Piggin return (char*)page; 32721da177e4SLinus Torvalds *ppage = page; 3273ebd09abbSDuane Griffin kaddr = kmap(page); 3274ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 3275ebd09abbSDuane Griffin return kaddr; 32761da177e4SLinus Torvalds } 32771da177e4SLinus Torvalds 32781da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 32791da177e4SLinus Torvalds { 32801da177e4SLinus Torvalds struct page *page = NULL; 32811da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 32821da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 32831da177e4SLinus Torvalds if (page) { 32841da177e4SLinus Torvalds kunmap(page); 32851da177e4SLinus Torvalds page_cache_release(page); 32861da177e4SLinus Torvalds } 32871da177e4SLinus Torvalds return res; 32881da177e4SLinus Torvalds } 32891da177e4SLinus Torvalds 3290cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 32911da177e4SLinus Torvalds { 3292cc314eefSLinus Torvalds struct page *page = NULL; 32931da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 3294cc314eefSLinus Torvalds return page; 32951da177e4SLinus Torvalds } 32961da177e4SLinus Torvalds 3297cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 32981da177e4SLinus Torvalds { 3299cc314eefSLinus Torvalds struct page *page = cookie; 3300cc314eefSLinus Torvalds 3301cc314eefSLinus Torvalds if (page) { 33021da177e4SLinus Torvalds kunmap(page); 33031da177e4SLinus Torvalds page_cache_release(page); 33041da177e4SLinus Torvalds } 33051da177e4SLinus Torvalds } 33061da177e4SLinus Torvalds 330754566b2cSNick Piggin /* 330854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 330954566b2cSNick Piggin */ 331054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 33111da177e4SLinus Torvalds { 33121da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 33130adb25d2SKirill Korotaev struct page *page; 3314afddba49SNick Piggin void *fsdata; 3315beb497abSDmitriy Monakhov int err; 33161da177e4SLinus Torvalds char *kaddr; 331754566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 331854566b2cSNick Piggin if (nofs) 331954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 33201da177e4SLinus Torvalds 33217e53cac4SNeilBrown retry: 3322afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 332354566b2cSNick Piggin flags, &page, &fsdata); 33241da177e4SLinus Torvalds if (err) 3325afddba49SNick Piggin goto fail; 3326afddba49SNick Piggin 33271da177e4SLinus Torvalds kaddr = kmap_atomic(page, KM_USER0); 33281da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 33291da177e4SLinus Torvalds kunmap_atomic(kaddr, KM_USER0); 3330afddba49SNick Piggin 3331afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 3332afddba49SNick Piggin page, fsdata); 33331da177e4SLinus Torvalds if (err < 0) 33341da177e4SLinus Torvalds goto fail; 3335afddba49SNick Piggin if (err < len-1) 3336afddba49SNick Piggin goto retry; 3337afddba49SNick Piggin 33381da177e4SLinus Torvalds mark_inode_dirty(inode); 33391da177e4SLinus Torvalds return 0; 33401da177e4SLinus Torvalds fail: 33411da177e4SLinus Torvalds return err; 33421da177e4SLinus Torvalds } 33431da177e4SLinus Torvalds 33440adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 33450adb25d2SKirill Korotaev { 33460adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 334754566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 33480adb25d2SKirill Korotaev } 33490adb25d2SKirill Korotaev 335092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 33511da177e4SLinus Torvalds .readlink = generic_readlink, 33521da177e4SLinus Torvalds .follow_link = page_follow_link_light, 33531da177e4SLinus Torvalds .put_link = page_put_link, 33541da177e4SLinus Torvalds }; 33551da177e4SLinus Torvalds 33562d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 3357cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 33581da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 33591da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 33601da177e4SLinus Torvalds EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ 33611da177e4SLinus Torvalds EXPORT_SYMBOL(getname); 33621da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 33631da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 33641da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 33651da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 33661da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 33670adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 33681da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 33691da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 3370d1811465SAl Viro EXPORT_SYMBOL(kern_path); 337116f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 3372f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 33731da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 33741da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 33751da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 33761da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 33771da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 33781da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 33791da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 33801da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 33811da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 33821da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 33831da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 33841da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 33851da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 33861da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 3387