11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 371da177e4SLinus Torvalds #include <asm/uaccess.h> 381da177e4SLinus Torvalds 39e81e3f4dSEric Paris #include "internal.h" 40c7105365SAl Viro #include "mount.h" 41e81e3f4dSEric Paris 421da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 431da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 441da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 451da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 461da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 471da177e4SLinus Torvalds * 481da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 491da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 501da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 511da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 521da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 531da177e4SLinus Torvalds * the special cases of the former code. 541da177e4SLinus Torvalds * 551da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 561da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 571da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 601da177e4SLinus Torvalds * resolution to correspond with current state of the code. 611da177e4SLinus Torvalds * 621da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 631da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 641da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 651da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 661da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 671da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 681da177e4SLinus Torvalds */ 691da177e4SLinus Torvalds 701da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 711da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 721da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 731da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 741da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 751da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7625985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 771da177e4SLinus Torvalds * 781da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 791da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 801da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 811da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 821da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 831da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 841da177e4SLinus Torvalds * and in the old Linux semantics. 851da177e4SLinus Torvalds */ 861da177e4SLinus Torvalds 871da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 881da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 891da177e4SLinus Torvalds * 901da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds 931da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 941da177e4SLinus Torvalds * inside the path - always follow. 951da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 961da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 971da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 981da177e4SLinus Torvalds * otherwise - don't follow. 991da177e4SLinus Torvalds * (applied in that order). 1001da177e4SLinus Torvalds * 1011da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1021da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1031da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1041da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1051da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1061da177e4SLinus Torvalds */ 1071da177e4SLinus Torvalds /* 1081da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 109a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1101da177e4SLinus Torvalds * any extra contention... 1111da177e4SLinus Torvalds */ 1121da177e4SLinus Torvalds 1131da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1141da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1151da177e4SLinus Torvalds * kernel data space before using them.. 1161da177e4SLinus Torvalds * 1171da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1181da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1191da177e4SLinus Torvalds */ 12091a27b2aSJeff Layton void final_putname(struct filename *name) 1211da177e4SLinus Torvalds { 1227950e385SJeff Layton if (name->separate) { 12391a27b2aSJeff Layton __putname(name->name); 12491a27b2aSJeff Layton kfree(name); 1257950e385SJeff Layton } else { 1267950e385SJeff Layton __putname(name); 12791a27b2aSJeff Layton } 1287950e385SJeff Layton } 1297950e385SJeff Layton 1307950e385SJeff Layton #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) 13191a27b2aSJeff Layton 13291a27b2aSJeff Layton static struct filename * 13391a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 13491a27b2aSJeff Layton { 13591a27b2aSJeff Layton struct filename *result, *err; 1363f9f0aa6SLinus Torvalds int len; 1377950e385SJeff Layton long max; 1387950e385SJeff Layton char *kname; 1391da177e4SLinus Torvalds 1407ac86265SJeff Layton result = audit_reusename(filename); 1417ac86265SJeff Layton if (result) 1427ac86265SJeff Layton return result; 1437ac86265SJeff Layton 1447950e385SJeff Layton result = __getname(); 1453f9f0aa6SLinus Torvalds if (unlikely(!result)) 1464043cde8SEric Paris return ERR_PTR(-ENOMEM); 1471da177e4SLinus Torvalds 1487950e385SJeff Layton /* 1497950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1507950e385SJeff Layton * allocation 1517950e385SJeff Layton */ 1527950e385SJeff Layton kname = (char *)result + sizeof(*result); 15391a27b2aSJeff Layton result->name = kname; 1547950e385SJeff Layton result->separate = false; 1557950e385SJeff Layton max = EMBEDDED_NAME_MAX; 1567950e385SJeff Layton 1577950e385SJeff Layton recopy: 1587950e385SJeff Layton len = strncpy_from_user(kname, filename, max); 15991a27b2aSJeff Layton if (unlikely(len < 0)) { 1603f9f0aa6SLinus Torvalds err = ERR_PTR(len); 1613f9f0aa6SLinus Torvalds goto error; 16291a27b2aSJeff Layton } 1633f9f0aa6SLinus Torvalds 1647950e385SJeff Layton /* 1657950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1667950e385SJeff Layton * separate struct filename so we can dedicate the entire 1677950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1687950e385SJeff Layton * userland. 1697950e385SJeff Layton */ 1707950e385SJeff Layton if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { 1717950e385SJeff Layton kname = (char *)result; 1727950e385SJeff Layton 1737950e385SJeff Layton result = kzalloc(sizeof(*result), GFP_KERNEL); 1747950e385SJeff Layton if (!result) { 1757950e385SJeff Layton err = ERR_PTR(-ENOMEM); 1767950e385SJeff Layton result = (struct filename *)kname; 1777950e385SJeff Layton goto error; 1787950e385SJeff Layton } 1797950e385SJeff Layton result->name = kname; 1807950e385SJeff Layton result->separate = true; 1817950e385SJeff Layton max = PATH_MAX; 1827950e385SJeff Layton goto recopy; 1837950e385SJeff Layton } 1847950e385SJeff Layton 1853f9f0aa6SLinus Torvalds /* The empty path is special. */ 1863f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1873f9f0aa6SLinus Torvalds if (empty) 1881fa1e7f6SAndy Whitcroft *empty = 1; 1893f9f0aa6SLinus Torvalds err = ERR_PTR(-ENOENT); 1903f9f0aa6SLinus Torvalds if (!(flags & LOOKUP_EMPTY)) 1913f9f0aa6SLinus Torvalds goto error; 1921da177e4SLinus Torvalds } 1933f9f0aa6SLinus Torvalds 1943f9f0aa6SLinus Torvalds err = ERR_PTR(-ENAMETOOLONG); 1957950e385SJeff Layton if (unlikely(len >= PATH_MAX)) 1967950e385SJeff Layton goto error; 1977950e385SJeff Layton 1987950e385SJeff Layton result->uptr = filename; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2011da177e4SLinus Torvalds 2023f9f0aa6SLinus Torvalds error: 2037950e385SJeff Layton final_putname(result); 2043f9f0aa6SLinus Torvalds return err; 2053f9f0aa6SLinus Torvalds } 2063f9f0aa6SLinus Torvalds 20791a27b2aSJeff Layton struct filename * 20891a27b2aSJeff Layton getname(const char __user * filename) 209f52e0c11SAl Viro { 210f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 211f52e0c11SAl Viro } 21291a27b2aSJeff Layton EXPORT_SYMBOL(getname); 213f52e0c11SAl Viro 2141da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 21591a27b2aSJeff Layton void putname(struct filename *name) 2161da177e4SLinus Torvalds { 2175ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 21891a27b2aSJeff Layton return audit_putname(name); 21991a27b2aSJeff Layton final_putname(name); 2201da177e4SLinus Torvalds } 2211da177e4SLinus Torvalds #endif 2221da177e4SLinus Torvalds 223e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 224e77819e5SLinus Torvalds { 22584635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 226e77819e5SLinus Torvalds struct posix_acl *acl; 227e77819e5SLinus Torvalds 228e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2293567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2303567866bSAl Viro if (!acl) 231e77819e5SLinus Torvalds return -EAGAIN; 2323567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2333567866bSAl Viro if (acl == ACL_NOT_CACHED) 234e77819e5SLinus Torvalds return -ECHILD; 235206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 236e77819e5SLinus Torvalds } 237e77819e5SLinus Torvalds 238e77819e5SLinus Torvalds acl = get_cached_acl(inode, ACL_TYPE_ACCESS); 239e77819e5SLinus Torvalds 240e77819e5SLinus Torvalds /* 2414e34e719SChristoph Hellwig * A filesystem can force a ACL callback by just never filling the 2424e34e719SChristoph Hellwig * ACL cache. But normally you'd fill the cache either at inode 2434e34e719SChristoph Hellwig * instantiation time, or on the first ->get_acl call. 244e77819e5SLinus Torvalds * 2454e34e719SChristoph Hellwig * If the filesystem doesn't have a get_acl() function at all, we'll 2464e34e719SChristoph Hellwig * just create the negative cache entry. 247e77819e5SLinus Torvalds */ 248e77819e5SLinus Torvalds if (acl == ACL_NOT_CACHED) { 2494e34e719SChristoph Hellwig if (inode->i_op->get_acl) { 2504e34e719SChristoph Hellwig acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); 2514e34e719SChristoph Hellwig if (IS_ERR(acl)) 2524e34e719SChristoph Hellwig return PTR_ERR(acl); 2534e34e719SChristoph Hellwig } else { 254e77819e5SLinus Torvalds set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); 255e77819e5SLinus Torvalds return -EAGAIN; 256e77819e5SLinus Torvalds } 2574e34e719SChristoph Hellwig } 258e77819e5SLinus Torvalds 259e77819e5SLinus Torvalds if (acl) { 260e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 261e77819e5SLinus Torvalds posix_acl_release(acl); 262e77819e5SLinus Torvalds return error; 263e77819e5SLinus Torvalds } 26484635d68SLinus Torvalds #endif 265e77819e5SLinus Torvalds 266e77819e5SLinus Torvalds return -EAGAIN; 267e77819e5SLinus Torvalds } 268e77819e5SLinus Torvalds 2695909ccaaSLinus Torvalds /* 270948409c7SAndreas Gruenbacher * This does the basic permission checking 2715909ccaaSLinus Torvalds */ 2727e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2735909ccaaSLinus Torvalds { 27426cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2755909ccaaSLinus Torvalds 2768e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2775909ccaaSLinus Torvalds mode >>= 6; 2785909ccaaSLinus Torvalds else { 279e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2807e40145eSAl Viro int error = check_acl(inode, mask); 2815909ccaaSLinus Torvalds if (error != -EAGAIN) 2825909ccaaSLinus Torvalds return error; 2835909ccaaSLinus Torvalds } 2845909ccaaSLinus Torvalds 2855909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 2865909ccaaSLinus Torvalds mode >>= 3; 2875909ccaaSLinus Torvalds } 2885909ccaaSLinus Torvalds 2895909ccaaSLinus Torvalds /* 2905909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 2915909ccaaSLinus Torvalds */ 2929c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 2935909ccaaSLinus Torvalds return 0; 2945909ccaaSLinus Torvalds return -EACCES; 2955909ccaaSLinus Torvalds } 2961da177e4SLinus Torvalds 2971da177e4SLinus Torvalds /** 2981da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 2991da177e4SLinus Torvalds * @inode: inode to check access rights for 3008fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3011da177e4SLinus Torvalds * 3021da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3031da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3041da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 305b74c79e9SNick Piggin * are used for other things. 306b74c79e9SNick Piggin * 307b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 308b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 309b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3101da177e4SLinus Torvalds */ 3112830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3121da177e4SLinus Torvalds { 3135909ccaaSLinus Torvalds int ret; 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds /* 316948409c7SAndreas Gruenbacher * Do the basic permission checks. 3171da177e4SLinus Torvalds */ 3187e40145eSAl Viro ret = acl_permission_check(inode, mask); 3195909ccaaSLinus Torvalds if (ret != -EACCES) 3205909ccaaSLinus Torvalds return ret; 3211da177e4SLinus Torvalds 322d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 323d594e7ecSAl Viro /* DACs are overridable for directories */ 3241a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 325d594e7ecSAl Viro return 0; 326d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 3271a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 328d594e7ecSAl Viro return 0; 329d594e7ecSAl Viro return -EACCES; 330d594e7ecSAl Viro } 3311da177e4SLinus Torvalds /* 3321da177e4SLinus Torvalds * Read/write DACs are always overridable. 333d594e7ecSAl Viro * Executable DACs are overridable when there is 334d594e7ecSAl Viro * at least one exec bit set. 3351da177e4SLinus Torvalds */ 336d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3371a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_OVERRIDE)) 3381da177e4SLinus Torvalds return 0; 3391da177e4SLinus Torvalds 3401da177e4SLinus Torvalds /* 3411da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3421da177e4SLinus Torvalds */ 3437ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 344d594e7ecSAl Viro if (mask == MAY_READ) 3451a48e2acSEric W. Biederman if (inode_capable(inode, CAP_DAC_READ_SEARCH)) 3461da177e4SLinus Torvalds return 0; 3471da177e4SLinus Torvalds 3481da177e4SLinus Torvalds return -EACCES; 3491da177e4SLinus Torvalds } 3501da177e4SLinus Torvalds 3513ddcd056SLinus Torvalds /* 3523ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3533ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3543ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3553ddcd056SLinus Torvalds * permission function, use the fast case". 3563ddcd056SLinus Torvalds */ 3573ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3583ddcd056SLinus Torvalds { 3593ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3603ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3613ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3623ddcd056SLinus Torvalds 3633ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3643ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3653ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3663ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3673ddcd056SLinus Torvalds } 3683ddcd056SLinus Torvalds return generic_permission(inode, mask); 3693ddcd056SLinus Torvalds } 3703ddcd056SLinus Torvalds 371cb23beb5SChristoph Hellwig /** 3720bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3730bdaea90SDavid Howells * @inode: Inode to check permission on 3740bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 375cb23beb5SChristoph Hellwig * 3760bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 377948409c7SAndreas Gruenbacher * 378948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3790bdaea90SDavid Howells * 3800bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 3810bdaea90SDavid Howells * inode_permission(). 382cb23beb5SChristoph Hellwig */ 3830bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 3841da177e4SLinus Torvalds { 385e6305c43SAl Viro int retval; 3861da177e4SLinus Torvalds 3873ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 3881da177e4SLinus Torvalds /* 3891da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 3901da177e4SLinus Torvalds */ 3911da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 3921da177e4SLinus Torvalds return -EACCES; 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds 3953ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 3961da177e4SLinus Torvalds if (retval) 3971da177e4SLinus Torvalds return retval; 3981da177e4SLinus Torvalds 39908ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 40008ce5f16SSerge E. Hallyn if (retval) 40108ce5f16SSerge E. Hallyn return retval; 40208ce5f16SSerge E. Hallyn 403d09ca739SEric Paris return security_inode_permission(inode, mask); 4041da177e4SLinus Torvalds } 4051da177e4SLinus Torvalds 406f4d6ff89SAl Viro /** 4070bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4080bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 40955852635SRandy Dunlap * @inode: Inode to check permission on 4100bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4110bdaea90SDavid Howells * 4120bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4130bdaea90SDavid Howells */ 4140bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4150bdaea90SDavid Howells { 4160bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4170bdaea90SDavid Howells umode_t mode = inode->i_mode; 4180bdaea90SDavid Howells 4190bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4200bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4210bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4220bdaea90SDavid Howells return -EROFS; 4230bdaea90SDavid Howells } 4240bdaea90SDavid Howells return 0; 4250bdaea90SDavid Howells } 4260bdaea90SDavid Howells 4270bdaea90SDavid Howells /** 4280bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4290bdaea90SDavid Howells * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4330bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4340bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4350bdaea90SDavid Howells * 4360bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4370bdaea90SDavid Howells */ 4380bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4390bdaea90SDavid Howells { 4400bdaea90SDavid Howells int retval; 4410bdaea90SDavid Howells 4420bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4430bdaea90SDavid Howells if (retval) 4440bdaea90SDavid Howells return retval; 4450bdaea90SDavid Howells return __inode_permission(inode, mask); 4460bdaea90SDavid Howells } 4470bdaea90SDavid Howells 4480bdaea90SDavid Howells /** 4495dd784d0SJan Blunck * path_get - get a reference to a path 4505dd784d0SJan Blunck * @path: path to get the reference to 4515dd784d0SJan Blunck * 4525dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4535dd784d0SJan Blunck */ 454dcf787f3SAl Viro void path_get(const struct path *path) 4555dd784d0SJan Blunck { 4565dd784d0SJan Blunck mntget(path->mnt); 4575dd784d0SJan Blunck dget(path->dentry); 4585dd784d0SJan Blunck } 4595dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4605dd784d0SJan Blunck 4615dd784d0SJan Blunck /** 4621d957f9bSJan Blunck * path_put - put a reference to a path 4631d957f9bSJan Blunck * @path: path to put the reference to 4641d957f9bSJan Blunck * 4651d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4661d957f9bSJan Blunck */ 467dcf787f3SAl Viro void path_put(const struct path *path) 4681da177e4SLinus Torvalds { 4691d957f9bSJan Blunck dput(path->dentry); 4701d957f9bSJan Blunck mntput(path->mnt); 4711da177e4SLinus Torvalds } 4721d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4731da177e4SLinus Torvalds 47419660af7SAl Viro /* 47531e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 47619660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 47719660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 47819660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 47919660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 48019660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 48119660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 48219660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 48331e6b01fSNick Piggin */ 48431e6b01fSNick Piggin 48532a7991bSAl Viro static inline void lock_rcu_walk(void) 48632a7991bSAl Viro { 48732a7991bSAl Viro br_read_lock(&vfsmount_lock); 48832a7991bSAl Viro rcu_read_lock(); 48932a7991bSAl Viro } 49032a7991bSAl Viro 49132a7991bSAl Viro static inline void unlock_rcu_walk(void) 49232a7991bSAl Viro { 49332a7991bSAl Viro rcu_read_unlock(); 49432a7991bSAl Viro br_read_unlock(&vfsmount_lock); 49532a7991bSAl Viro } 49632a7991bSAl Viro 49731e6b01fSNick Piggin /** 49819660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 49919660af7SAl Viro * @nd: nameidata pathwalk data 50019660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 50139191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 50231e6b01fSNick Piggin * 50319660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 50419660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 50519660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 50631e6b01fSNick Piggin */ 50719660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 50831e6b01fSNick Piggin { 50931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 51031e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 51131e6b01fSNick Piggin 51231e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 513e5c832d5SLinus Torvalds 514e5c832d5SLinus Torvalds /* 515e5c832d5SLinus Torvalds * Get a reference to the parent first: we're 516e5c832d5SLinus Torvalds * going to make "path_put(nd->path)" valid in 517e5c832d5SLinus Torvalds * non-RCU context for "terminate_walk()". 518e5c832d5SLinus Torvalds * 519e5c832d5SLinus Torvalds * If this doesn't work, return immediately with 520e5c832d5SLinus Torvalds * RCU walking still active (and then we will do 521e5c832d5SLinus Torvalds * the RCU walk cleanup in terminate_walk()). 522e5c832d5SLinus Torvalds */ 523e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&parent->d_lockref)) 524e5c832d5SLinus Torvalds return -ECHILD; 525e5c832d5SLinus Torvalds 526e5c832d5SLinus Torvalds /* 527e5c832d5SLinus Torvalds * After the mntget(), we terminate_walk() will do 528e5c832d5SLinus Torvalds * the right thing for non-RCU mode, and all our 529e5c832d5SLinus Torvalds * subsequent exit cases should unlock_rcu_walk() 530e5c832d5SLinus Torvalds * before returning. 531e5c832d5SLinus Torvalds */ 532e5c832d5SLinus Torvalds mntget(nd->path.mnt); 533e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 53415570086SLinus Torvalds 53515570086SLinus Torvalds /* 53615570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 53715570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 53815570086SLinus Torvalds * 53915570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 54015570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 54115570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 54215570086SLinus Torvalds * since we checked the sequence number of the parent after we got 54315570086SLinus Torvalds * the child sequence number. So we know the parent must still 54415570086SLinus Torvalds * be valid if the child sequence number is still valid. 54515570086SLinus Torvalds */ 54619660af7SAl Viro if (!dentry) { 547e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 548e5c832d5SLinus Torvalds goto out; 54919660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 55019660af7SAl Viro } else { 551e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 552e5c832d5SLinus Torvalds goto out; 553e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 554e5c832d5SLinus Torvalds goto drop_dentry; 55519660af7SAl Viro } 556e5c832d5SLinus Torvalds 557e5c832d5SLinus Torvalds /* 558e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 559e5c832d5SLinus Torvalds * still valid and get it if required. 560e5c832d5SLinus Torvalds */ 561e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 562e5c832d5SLinus Torvalds spin_lock(&fs->lock); 563e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 564e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 56531e6b01fSNick Piggin path_get(&nd->root); 56631e6b01fSNick Piggin spin_unlock(&fs->lock); 56731e6b01fSNick Piggin } 56831e6b01fSNick Piggin 56932a7991bSAl Viro unlock_rcu_walk(); 57031e6b01fSNick Piggin return 0; 57119660af7SAl Viro 572e5c832d5SLinus Torvalds unlock_and_drop_dentry: 57331e6b01fSNick Piggin spin_unlock(&fs->lock); 574e5c832d5SLinus Torvalds drop_dentry: 575e5c832d5SLinus Torvalds unlock_rcu_walk(); 576e5c832d5SLinus Torvalds dput(dentry); 577e5c832d5SLinus Torvalds return -ECHILD; 578e5c832d5SLinus Torvalds out: 579e5c832d5SLinus Torvalds unlock_rcu_walk(); 58031e6b01fSNick Piggin return -ECHILD; 58131e6b01fSNick Piggin } 58231e6b01fSNick Piggin 5834ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 58434286d66SNick Piggin { 5854ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 58634286d66SNick Piggin } 58734286d66SNick Piggin 5889f1fafeeSAl Viro /** 5899f1fafeeSAl Viro * complete_walk - successful completion of path walk 5909f1fafeeSAl Viro * @nd: pointer nameidata 59139159de2SJeff Layton * 5929f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5939f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5949f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5959f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5969f1fafeeSAl Viro * need to drop nd->path. 59739159de2SJeff Layton */ 5989f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 59939159de2SJeff Layton { 60016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 60139159de2SJeff Layton int status; 60239159de2SJeff Layton 6039f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6049f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6059f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6069f1fafeeSAl Viro nd->root.mnt = NULL; 60715570086SLinus Torvalds 608e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 60932a7991bSAl Viro unlock_rcu_walk(); 6109f1fafeeSAl Viro return -ECHILD; 6119f1fafeeSAl Viro } 612e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 613e5c832d5SLinus Torvalds unlock_rcu_walk(); 614e5c832d5SLinus Torvalds dput(dentry); 615e5c832d5SLinus Torvalds return -ECHILD; 616e5c832d5SLinus Torvalds } 6179f1fafeeSAl Viro mntget(nd->path.mnt); 61832a7991bSAl Viro unlock_rcu_walk(); 6199f1fafeeSAl Viro } 6209f1fafeeSAl Viro 62116c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 62239159de2SJeff Layton return 0; 62339159de2SJeff Layton 624ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 62516c2cd71SAl Viro return 0; 62616c2cd71SAl Viro 627ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 62839159de2SJeff Layton if (status > 0) 62939159de2SJeff Layton return 0; 63039159de2SJeff Layton 63116c2cd71SAl Viro if (!status) 63239159de2SJeff Layton status = -ESTALE; 63316c2cd71SAl Viro 6349f1fafeeSAl Viro path_put(&nd->path); 63539159de2SJeff Layton return status; 63639159de2SJeff Layton } 63739159de2SJeff Layton 6382a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6392a737871SAl Viro { 640f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 641f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6422a737871SAl Viro } 6432a737871SAl Viro 6446de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6456de88d72SAl Viro 64631e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 64731e6b01fSNick Piggin { 64831e6b01fSNick Piggin if (!nd->root.mnt) { 64931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 650c28cc364SNick Piggin unsigned seq; 651c28cc364SNick Piggin 652c28cc364SNick Piggin do { 653c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 65431e6b01fSNick Piggin nd->root = fs->root; 655c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 656c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 65731e6b01fSNick Piggin } 65831e6b01fSNick Piggin } 65931e6b01fSNick Piggin 660f1662356SArjan van de Ven static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) 6611da177e4SLinus Torvalds { 66231e6b01fSNick Piggin int ret; 66331e6b01fSNick Piggin 6641da177e4SLinus Torvalds if (IS_ERR(link)) 6651da177e4SLinus Torvalds goto fail; 6661da177e4SLinus Torvalds 6671da177e4SLinus Torvalds if (*link == '/') { 6682a737871SAl Viro set_root(nd); 6691d957f9bSJan Blunck path_put(&nd->path); 6702a737871SAl Viro nd->path = nd->root; 6712a737871SAl Viro path_get(&nd->root); 67216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 6731da177e4SLinus Torvalds } 67431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 675b4091d5fSChristoph Hellwig 67631e6b01fSNick Piggin ret = link_path_walk(link, nd); 67731e6b01fSNick Piggin return ret; 6781da177e4SLinus Torvalds fail: 6791d957f9bSJan Blunck path_put(&nd->path); 6801da177e4SLinus Torvalds return PTR_ERR(link); 6811da177e4SLinus Torvalds } 6821da177e4SLinus Torvalds 6831d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 684051d3812SIan Kent { 685051d3812SIan Kent dput(path->dentry); 6864ac91378SJan Blunck if (path->mnt != nd->path.mnt) 687051d3812SIan Kent mntput(path->mnt); 688051d3812SIan Kent } 689051d3812SIan Kent 6907b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6917b9337aaSNick Piggin struct nameidata *nd) 692051d3812SIan Kent { 69331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6944ac91378SJan Blunck dput(nd->path.dentry); 69531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6964ac91378SJan Blunck mntput(nd->path.mnt); 6979a229683SHuang Shijie } 69831e6b01fSNick Piggin nd->path.mnt = path->mnt; 6994ac91378SJan Blunck nd->path.dentry = path->dentry; 700051d3812SIan Kent } 701051d3812SIan Kent 702b5fb63c1SChristoph Hellwig /* 703b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 704b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 705b5fb63c1SChristoph Hellwig */ 706b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 707b5fb63c1SChristoph Hellwig { 708b5fb63c1SChristoph Hellwig path_put(&nd->path); 709b5fb63c1SChristoph Hellwig 710b5fb63c1SChristoph Hellwig nd->path = *path; 711b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 712b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 713b5fb63c1SChristoph Hellwig } 714b5fb63c1SChristoph Hellwig 715574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 716574197e0SAl Viro { 717574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 7186d7b5aaeSAl Viro if (inode->i_op->put_link) 719574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 720574197e0SAl Viro path_put(link); 721574197e0SAl Viro } 722574197e0SAl Viro 723561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 724561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 725800179c9SKees Cook 726800179c9SKees Cook /** 727800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 728800179c9SKees Cook * @link: The path of the symlink 72955852635SRandy Dunlap * @nd: nameidata pathwalk data 730800179c9SKees Cook * 731800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 732800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 733800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 734800179c9SKees Cook * processes from failing races against path names that may change out 735800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 736800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 737800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 738800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 739800179c9SKees Cook * 740800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 741800179c9SKees Cook */ 742800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 743800179c9SKees Cook { 744800179c9SKees Cook const struct inode *inode; 745800179c9SKees Cook const struct inode *parent; 746800179c9SKees Cook 747800179c9SKees Cook if (!sysctl_protected_symlinks) 748800179c9SKees Cook return 0; 749800179c9SKees Cook 750800179c9SKees Cook /* Allowed if owner and follower match. */ 751800179c9SKees Cook inode = link->dentry->d_inode; 75281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 753800179c9SKees Cook return 0; 754800179c9SKees Cook 755800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 756800179c9SKees Cook parent = nd->path.dentry->d_inode; 757800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 758800179c9SKees Cook return 0; 759800179c9SKees Cook 760800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 76181abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 762800179c9SKees Cook return 0; 763800179c9SKees Cook 764ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 765800179c9SKees Cook path_put_conditional(link, nd); 766800179c9SKees Cook path_put(&nd->path); 767800179c9SKees Cook return -EACCES; 768800179c9SKees Cook } 769800179c9SKees Cook 770800179c9SKees Cook /** 771800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 772800179c9SKees Cook * @inode: the source inode to hardlink from 773800179c9SKees Cook * 774800179c9SKees Cook * Return false if at least one of the following conditions: 775800179c9SKees Cook * - inode is not a regular file 776800179c9SKees Cook * - inode is setuid 777800179c9SKees Cook * - inode is setgid and group-exec 778800179c9SKees Cook * - access failure for read and write 779800179c9SKees Cook * 780800179c9SKees Cook * Otherwise returns true. 781800179c9SKees Cook */ 782800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 783800179c9SKees Cook { 784800179c9SKees Cook umode_t mode = inode->i_mode; 785800179c9SKees Cook 786800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 787800179c9SKees Cook if (!S_ISREG(mode)) 788800179c9SKees Cook return false; 789800179c9SKees Cook 790800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 791800179c9SKees Cook if (mode & S_ISUID) 792800179c9SKees Cook return false; 793800179c9SKees Cook 794800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 795800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 796800179c9SKees Cook return false; 797800179c9SKees Cook 798800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 799800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 800800179c9SKees Cook return false; 801800179c9SKees Cook 802800179c9SKees Cook return true; 803800179c9SKees Cook } 804800179c9SKees Cook 805800179c9SKees Cook /** 806800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 807800179c9SKees Cook * @link: the source to hardlink from 808800179c9SKees Cook * 809800179c9SKees Cook * Block hardlink when all of: 810800179c9SKees Cook * - sysctl_protected_hardlinks enabled 811800179c9SKees Cook * - fsuid does not match inode 812800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 813800179c9SKees Cook * - not CAP_FOWNER 814800179c9SKees Cook * 815800179c9SKees Cook * Returns 0 if successful, -ve on error. 816800179c9SKees Cook */ 817800179c9SKees Cook static int may_linkat(struct path *link) 818800179c9SKees Cook { 819800179c9SKees Cook const struct cred *cred; 820800179c9SKees Cook struct inode *inode; 821800179c9SKees Cook 822800179c9SKees Cook if (!sysctl_protected_hardlinks) 823800179c9SKees Cook return 0; 824800179c9SKees Cook 825800179c9SKees Cook cred = current_cred(); 826800179c9SKees Cook inode = link->dentry->d_inode; 827800179c9SKees Cook 828800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 829800179c9SKees Cook * otherwise, it must be a safe source. 830800179c9SKees Cook */ 83181abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 832800179c9SKees Cook capable(CAP_FOWNER)) 833800179c9SKees Cook return 0; 834800179c9SKees Cook 835a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 836800179c9SKees Cook return -EPERM; 837800179c9SKees Cook } 838800179c9SKees Cook 839def4af30SAl Viro static __always_inline int 840574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 8411da177e4SLinus Torvalds { 8427b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8436d7b5aaeSAl Viro int error; 8446d7b5aaeSAl Viro char *s; 8451da177e4SLinus Torvalds 846844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 847844a3917SAl Viro 8480e794589SAl Viro if (link->mnt == nd->path.mnt) 8490e794589SAl Viro mntget(link->mnt); 8500e794589SAl Viro 8516d7b5aaeSAl Viro error = -ELOOP; 8526d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8536d7b5aaeSAl Viro goto out_put_nd_path; 8546d7b5aaeSAl Viro 855574197e0SAl Viro cond_resched(); 856574197e0SAl Viro current->total_link_count++; 857574197e0SAl Viro 85868ac1234SAl Viro touch_atime(link); 8591da177e4SLinus Torvalds nd_set_link(nd, NULL); 860cd4e91d3SAl Viro 86136f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8626d7b5aaeSAl Viro if (error) 8636d7b5aaeSAl Viro goto out_put_nd_path; 86436f3b4f6SAl Viro 86586acdca1SAl Viro nd->last_type = LAST_BIND; 866def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 867def4af30SAl Viro error = PTR_ERR(*p); 8686d7b5aaeSAl Viro if (IS_ERR(*p)) 869408ef013SChristoph Hellwig goto out_put_nd_path; 8706d7b5aaeSAl Viro 871cc314eefSLinus Torvalds error = 0; 8726d7b5aaeSAl Viro s = nd_get_link(nd); 8736d7b5aaeSAl Viro if (s) { 8741da177e4SLinus Torvalds error = __vfs_follow_link(nd, s); 8756d7b5aaeSAl Viro if (unlikely(error)) 8766d7b5aaeSAl Viro put_link(nd, link, *p); 877b5fb63c1SChristoph Hellwig } 8786d7b5aaeSAl Viro 8796d7b5aaeSAl Viro return error; 8806d7b5aaeSAl Viro 8816d7b5aaeSAl Viro out_put_nd_path: 88298f6ef64SArnd Bergmann *p = NULL; 8836d7b5aaeSAl Viro path_put(&nd->path); 8846d7b5aaeSAl Viro path_put(link); 8851da177e4SLinus Torvalds return error; 8861da177e4SLinus Torvalds } 8871da177e4SLinus Torvalds 88831e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 88931e6b01fSNick Piggin { 8900714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8910714a533SAl Viro struct mount *parent; 89231e6b01fSNick Piggin struct dentry *mountpoint; 89331e6b01fSNick Piggin 8940714a533SAl Viro parent = mnt->mnt_parent; 8950714a533SAl Viro if (&parent->mnt == path->mnt) 89631e6b01fSNick Piggin return 0; 897a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 89831e6b01fSNick Piggin path->dentry = mountpoint; 8990714a533SAl Viro path->mnt = &parent->mnt; 90031e6b01fSNick Piggin return 1; 90131e6b01fSNick Piggin } 90231e6b01fSNick Piggin 903f015f126SDavid Howells /* 904f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 905f015f126SDavid Howells * 906f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 907f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 908f015f126SDavid Howells * Up is towards /. 909f015f126SDavid Howells * 910f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 911f015f126SDavid Howells * root. 912f015f126SDavid Howells */ 913bab77ebfSAl Viro int follow_up(struct path *path) 9141da177e4SLinus Torvalds { 9150714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9160714a533SAl Viro struct mount *parent; 9171da177e4SLinus Torvalds struct dentry *mountpoint; 91899b7db7bSNick Piggin 919962830dfSAndi Kleen br_read_lock(&vfsmount_lock); 9200714a533SAl Viro parent = mnt->mnt_parent; 9213c0a6163SAl Viro if (parent == mnt) { 922962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 9231da177e4SLinus Torvalds return 0; 9241da177e4SLinus Torvalds } 9250714a533SAl Viro mntget(&parent->mnt); 926a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 927962830dfSAndi Kleen br_read_unlock(&vfsmount_lock); 928bab77ebfSAl Viro dput(path->dentry); 929bab77ebfSAl Viro path->dentry = mountpoint; 930bab77ebfSAl Viro mntput(path->mnt); 9310714a533SAl Viro path->mnt = &parent->mnt; 9321da177e4SLinus Torvalds return 1; 9331da177e4SLinus Torvalds } 9341da177e4SLinus Torvalds 935b5c84bf6SNick Piggin /* 9369875cf80SDavid Howells * Perform an automount 9379875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9389875cf80SDavid Howells * were called with. 9391da177e4SLinus Torvalds */ 9409875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9419875cf80SDavid Howells bool *need_mntput) 94231e6b01fSNick Piggin { 9439875cf80SDavid Howells struct vfsmount *mnt; 944ea5b778aSDavid Howells int err; 9459875cf80SDavid Howells 9469875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9479875cf80SDavid Howells return -EREMOTE; 9489875cf80SDavid Howells 9490ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9500ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9510ec26fd0SMiklos Szeredi * the name. 9520ec26fd0SMiklos Szeredi * 9530ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9545a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9550ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9560ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9570ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9580ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9595a30d8a2SDavid Howells */ 9605a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 961d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9625a30d8a2SDavid Howells path->dentry->d_inode) 9639875cf80SDavid Howells return -EISDIR; 9640ec26fd0SMiklos Szeredi 9659875cf80SDavid Howells current->total_link_count++; 9669875cf80SDavid Howells if (current->total_link_count >= 40) 9679875cf80SDavid Howells return -ELOOP; 9689875cf80SDavid Howells 9699875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9709875cf80SDavid Howells if (IS_ERR(mnt)) { 9719875cf80SDavid Howells /* 9729875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9739875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9749875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9759875cf80SDavid Howells * 9769875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9779875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9789875cf80SDavid Howells * the path is inaccessible and we should say so. 9799875cf80SDavid Howells */ 98049084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9819875cf80SDavid Howells return -EREMOTE; 9829875cf80SDavid Howells return PTR_ERR(mnt); 98331e6b01fSNick Piggin } 984ea5b778aSDavid Howells 9859875cf80SDavid Howells if (!mnt) /* mount collision */ 9869875cf80SDavid Howells return 0; 9879875cf80SDavid Howells 9888aef1884SAl Viro if (!*need_mntput) { 9898aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9908aef1884SAl Viro mntget(path->mnt); 9918aef1884SAl Viro *need_mntput = true; 9928aef1884SAl Viro } 99319a167afSAl Viro err = finish_automount(mnt, path); 994ea5b778aSDavid Howells 995ea5b778aSDavid Howells switch (err) { 996ea5b778aSDavid Howells case -EBUSY: 997ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 99819a167afSAl Viro return 0; 999ea5b778aSDavid Howells case 0: 10008aef1884SAl Viro path_put(path); 10019875cf80SDavid Howells path->mnt = mnt; 10029875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10039875cf80SDavid Howells return 0; 100419a167afSAl Viro default: 100519a167afSAl Viro return err; 10069875cf80SDavid Howells } 100719a167afSAl Viro 1008ea5b778aSDavid Howells } 10099875cf80SDavid Howells 10109875cf80SDavid Howells /* 10119875cf80SDavid Howells * Handle a dentry that is managed in some way. 1012cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10139875cf80SDavid Howells * - Flagged as mountpoint 10149875cf80SDavid Howells * - Flagged as automount point 10159875cf80SDavid Howells * 10169875cf80SDavid Howells * This may only be called in refwalk mode. 10179875cf80SDavid Howells * 10189875cf80SDavid Howells * Serialization is taken care of in namespace.c 10199875cf80SDavid Howells */ 10209875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10219875cf80SDavid Howells { 10228aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10239875cf80SDavid Howells unsigned managed; 10249875cf80SDavid Howells bool need_mntput = false; 10258aef1884SAl Viro int ret = 0; 10269875cf80SDavid Howells 10279875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10289875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10299875cf80SDavid Howells * the components of that value change under us */ 10309875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10319875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10329875cf80SDavid Howells unlikely(managed != 0)) { 1033cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1034cc53ce53SDavid Howells * being held. */ 1035cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1036cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1037cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10381aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1039cc53ce53SDavid Howells if (ret < 0) 10408aef1884SAl Viro break; 1041cc53ce53SDavid Howells } 1042cc53ce53SDavid Howells 10439875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10449875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10459875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10469875cf80SDavid Howells if (mounted) { 10479875cf80SDavid Howells dput(path->dentry); 10489875cf80SDavid Howells if (need_mntput) 1049463ffb2eSAl Viro mntput(path->mnt); 1050463ffb2eSAl Viro path->mnt = mounted; 1051463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10529875cf80SDavid Howells need_mntput = true; 10539875cf80SDavid Howells continue; 1054463ffb2eSAl Viro } 1055463ffb2eSAl Viro 10569875cf80SDavid Howells /* Something is mounted on this dentry in another 10579875cf80SDavid Howells * namespace and/or whatever was mounted there in this 10589875cf80SDavid Howells * namespace got unmounted before we managed to get the 10599875cf80SDavid Howells * vfsmount_lock */ 10601da177e4SLinus Torvalds } 10619875cf80SDavid Howells 10629875cf80SDavid Howells /* Handle an automount point */ 10639875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10649875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10659875cf80SDavid Howells if (ret < 0) 10668aef1884SAl Viro break; 10679875cf80SDavid Howells continue; 10689875cf80SDavid Howells } 10699875cf80SDavid Howells 10709875cf80SDavid Howells /* We didn't change the current path point */ 10719875cf80SDavid Howells break; 10729875cf80SDavid Howells } 10738aef1884SAl Viro 10748aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10758aef1884SAl Viro mntput(path->mnt); 10768aef1884SAl Viro if (ret == -EISDIR) 10778aef1884SAl Viro ret = 0; 1078a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10791da177e4SLinus Torvalds } 10801da177e4SLinus Torvalds 1081cc53ce53SDavid Howells int follow_down_one(struct path *path) 10821da177e4SLinus Torvalds { 10831da177e4SLinus Torvalds struct vfsmount *mounted; 10841da177e4SLinus Torvalds 10851c755af4SAl Viro mounted = lookup_mnt(path); 10861da177e4SLinus Torvalds if (mounted) { 10879393bd07SAl Viro dput(path->dentry); 10889393bd07SAl Viro mntput(path->mnt); 10899393bd07SAl Viro path->mnt = mounted; 10909393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10911da177e4SLinus Torvalds return 1; 10921da177e4SLinus Torvalds } 10931da177e4SLinus Torvalds return 0; 10941da177e4SLinus Torvalds } 10951da177e4SLinus Torvalds 109662a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 109762a7375eSIan Kent { 109862a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 109962a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 110062a7375eSIan Kent } 110162a7375eSIan Kent 11029875cf80SDavid Howells /* 1103287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1104287548e4SAl Viro * we meet a managed dentry that would need blocking. 11059875cf80SDavid Howells */ 11069875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1107287548e4SAl Viro struct inode **inode) 11089875cf80SDavid Howells { 110962a7375eSIan Kent for (;;) { 1110c7105365SAl Viro struct mount *mounted; 111162a7375eSIan Kent /* 111262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 111362a7375eSIan Kent * that wants to block transit. 111462a7375eSIan Kent */ 1115287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 1116ab90911fSDavid Howells return false; 111762a7375eSIan Kent 111862a7375eSIan Kent if (!d_mountpoint(path->dentry)) 111962a7375eSIan Kent break; 112062a7375eSIan Kent 11219875cf80SDavid Howells mounted = __lookup_mnt(path->mnt, path->dentry, 1); 11229875cf80SDavid Howells if (!mounted) 11239875cf80SDavid Howells break; 1124c7105365SAl Viro path->mnt = &mounted->mnt; 1125c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1126a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11279875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 112859430262SLinus Torvalds /* 112959430262SLinus Torvalds * Update the inode too. We don't need to re-check the 113059430262SLinus Torvalds * dentry sequence number here after this d_inode read, 113159430262SLinus Torvalds * because a mount-point is always pinned. 113259430262SLinus Torvalds */ 113359430262SLinus Torvalds *inode = path->dentry->d_inode; 11349875cf80SDavid Howells } 11359875cf80SDavid Howells return true; 11369875cf80SDavid Howells } 11379875cf80SDavid Howells 1138dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 1139287548e4SAl Viro { 1140dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 1141c7105365SAl Viro struct mount *mounted; 1142dea39376SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); 1143287548e4SAl Viro if (!mounted) 1144287548e4SAl Viro break; 1145c7105365SAl Viro nd->path.mnt = &mounted->mnt; 1146c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 1147dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1148287548e4SAl Viro } 1149287548e4SAl Viro } 1150287548e4SAl Viro 115131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 115231e6b01fSNick Piggin { 115331e6b01fSNick Piggin set_root_rcu(nd); 115431e6b01fSNick Piggin 115531e6b01fSNick Piggin while (1) { 115631e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 115731e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 115831e6b01fSNick Piggin break; 115931e6b01fSNick Piggin } 116031e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 116131e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 116231e6b01fSNick Piggin struct dentry *parent = old->d_parent; 116331e6b01fSNick Piggin unsigned seq; 116431e6b01fSNick Piggin 116531e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 116631e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1167ef7562d5SAl Viro goto failed; 116831e6b01fSNick Piggin nd->path.dentry = parent; 116931e6b01fSNick Piggin nd->seq = seq; 117031e6b01fSNick Piggin break; 117131e6b01fSNick Piggin } 117231e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 117331e6b01fSNick Piggin break; 117431e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 117531e6b01fSNick Piggin } 1176dea39376SAl Viro follow_mount_rcu(nd); 1177dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 117831e6b01fSNick Piggin return 0; 1179ef7562d5SAl Viro 1180ef7562d5SAl Viro failed: 1181ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11825b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1183ef7562d5SAl Viro nd->root.mnt = NULL; 118432a7991bSAl Viro unlock_rcu_walk(); 1185ef7562d5SAl Viro return -ECHILD; 118631e6b01fSNick Piggin } 118731e6b01fSNick Piggin 11889875cf80SDavid Howells /* 1189cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1190cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1191cc53ce53SDavid Howells * caller is permitted to proceed or not. 1192cc53ce53SDavid Howells */ 11937cc90cc3SAl Viro int follow_down(struct path *path) 1194cc53ce53SDavid Howells { 1195cc53ce53SDavid Howells unsigned managed; 1196cc53ce53SDavid Howells int ret; 1197cc53ce53SDavid Howells 1198cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1199cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1200cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1201cc53ce53SDavid Howells * being held. 1202cc53ce53SDavid Howells * 1203cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1204cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1205cc53ce53SDavid Howells * other than its daemon the right to mount on its 1206cc53ce53SDavid Howells * superstructure. 1207cc53ce53SDavid Howells * 1208cc53ce53SDavid Howells * The filesystem may sleep at this point. 1209cc53ce53SDavid Howells */ 1210cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1211cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1212cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1213ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12141aed3e42SAl Viro path->dentry, false); 1215cc53ce53SDavid Howells if (ret < 0) 1216cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1217cc53ce53SDavid Howells } 1218cc53ce53SDavid Howells 1219cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1220cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1221cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1222cc53ce53SDavid Howells if (!mounted) 1223cc53ce53SDavid Howells break; 1224cc53ce53SDavid Howells dput(path->dentry); 1225cc53ce53SDavid Howells mntput(path->mnt); 1226cc53ce53SDavid Howells path->mnt = mounted; 1227cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1228cc53ce53SDavid Howells continue; 1229cc53ce53SDavid Howells } 1230cc53ce53SDavid Howells 1231cc53ce53SDavid Howells /* Don't handle automount points here */ 1232cc53ce53SDavid Howells break; 1233cc53ce53SDavid Howells } 1234cc53ce53SDavid Howells return 0; 1235cc53ce53SDavid Howells } 1236cc53ce53SDavid Howells 1237cc53ce53SDavid Howells /* 12389875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12399875cf80SDavid Howells */ 12409875cf80SDavid Howells static void follow_mount(struct path *path) 12419875cf80SDavid Howells { 12429875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12439875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12449875cf80SDavid Howells if (!mounted) 12459875cf80SDavid Howells break; 12469875cf80SDavid Howells dput(path->dentry); 12479875cf80SDavid Howells mntput(path->mnt); 12489875cf80SDavid Howells path->mnt = mounted; 12499875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12509875cf80SDavid Howells } 12519875cf80SDavid Howells } 12529875cf80SDavid Howells 125331e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12541da177e4SLinus Torvalds { 12552a737871SAl Viro set_root(nd); 1256e518ddb7SAndreas Mohr 12571da177e4SLinus Torvalds while(1) { 12584ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12591da177e4SLinus Torvalds 12602a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12612a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12621da177e4SLinus Torvalds break; 12631da177e4SLinus Torvalds } 12644ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12653088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12663088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12671da177e4SLinus Torvalds dput(old); 12681da177e4SLinus Torvalds break; 12691da177e4SLinus Torvalds } 12703088dd70SAl Viro if (!follow_up(&nd->path)) 12711da177e4SLinus Torvalds break; 12721da177e4SLinus Torvalds } 127379ed0226SAl Viro follow_mount(&nd->path); 127431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12751da177e4SLinus Torvalds } 12761da177e4SLinus Torvalds 12771da177e4SLinus Torvalds /* 1278bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1279bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1280bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1281bad61189SMiklos Szeredi * 1282bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1283baa03890SNick Piggin */ 1284bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1285201f956eSAl Viro unsigned int flags, bool *need_lookup) 1286baa03890SNick Piggin { 1287baa03890SNick Piggin struct dentry *dentry; 1288bad61189SMiklos Szeredi int error; 1289baa03890SNick Piggin 1290bad61189SMiklos Szeredi *need_lookup = false; 1291bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1292bad61189SMiklos Szeredi if (dentry) { 129339e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1294201f956eSAl Viro error = d_revalidate(dentry, flags); 1295bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1296bad61189SMiklos Szeredi if (error < 0) { 1297bad61189SMiklos Szeredi dput(dentry); 1298bad61189SMiklos Szeredi return ERR_PTR(error); 1299bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1300bad61189SMiklos Szeredi dput(dentry); 1301bad61189SMiklos Szeredi dentry = NULL; 1302bad61189SMiklos Szeredi } 1303bad61189SMiklos Szeredi } 1304bad61189SMiklos Szeredi } 1305bad61189SMiklos Szeredi } 1306baa03890SNick Piggin 1307bad61189SMiklos Szeredi if (!dentry) { 1308bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1309baa03890SNick Piggin if (unlikely(!dentry)) 1310baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1311baa03890SNick Piggin 1312bad61189SMiklos Szeredi *need_lookup = true; 1313baa03890SNick Piggin } 1314baa03890SNick Piggin return dentry; 1315baa03890SNick Piggin } 1316baa03890SNick Piggin 1317baa03890SNick Piggin /* 1318bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1319bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1320bad61189SMiklos Szeredi * 1321bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 132244396f4bSJosef Bacik */ 1323bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 132472bd866aSAl Viro unsigned int flags) 132544396f4bSJosef Bacik { 132644396f4bSJosef Bacik struct dentry *old; 132744396f4bSJosef Bacik 132844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1329bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1330e188dc02SMiklos Szeredi dput(dentry); 133144396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1332e188dc02SMiklos Szeredi } 133344396f4bSJosef Bacik 133472bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 133544396f4bSJosef Bacik if (unlikely(old)) { 133644396f4bSJosef Bacik dput(dentry); 133744396f4bSJosef Bacik dentry = old; 133844396f4bSJosef Bacik } 133944396f4bSJosef Bacik return dentry; 134044396f4bSJosef Bacik } 134144396f4bSJosef Bacik 1342a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 134372bd866aSAl Viro struct dentry *base, unsigned int flags) 1344a3255546SAl Viro { 1345bad61189SMiklos Szeredi bool need_lookup; 1346a3255546SAl Viro struct dentry *dentry; 1347a3255546SAl Viro 134872bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1349bad61189SMiklos Szeredi if (!need_lookup) 1350a3255546SAl Viro return dentry; 1351bad61189SMiklos Szeredi 135272bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1353a3255546SAl Viro } 1354a3255546SAl Viro 135544396f4bSJosef Bacik /* 13561da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13571da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13581da177e4SLinus Torvalds * It _is_ time-critical. 13591da177e4SLinus Torvalds */ 1360e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 136131e6b01fSNick Piggin struct path *path, struct inode **inode) 13621da177e4SLinus Torvalds { 13634ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 136431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13655a18fff2SAl Viro int need_reval = 1; 13665a18fff2SAl Viro int status = 1; 13679875cf80SDavid Howells int err; 13689875cf80SDavid Howells 13693cac260aSAl Viro /* 1370b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1371b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1372b04f784eSNick Piggin * do the non-racy lookup, below. 1373b04f784eSNick Piggin */ 137431e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 137531e6b01fSNick Piggin unsigned seq; 1376da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13775a18fff2SAl Viro if (!dentry) 13785a18fff2SAl Viro goto unlazy; 13795a18fff2SAl Viro 138012f8ad4bSLinus Torvalds /* 138112f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 138212f8ad4bSLinus Torvalds * the dentry name information from lookup. 138312f8ad4bSLinus Torvalds */ 138412f8ad4bSLinus Torvalds *inode = dentry->d_inode; 138512f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 138612f8ad4bSLinus Torvalds return -ECHILD; 138712f8ad4bSLinus Torvalds 138812f8ad4bSLinus Torvalds /* 138912f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 139012f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 139112f8ad4bSLinus Torvalds * 139212f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 139312f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 139412f8ad4bSLinus Torvalds */ 139531e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 139631e6b01fSNick Piggin return -ECHILD; 139731e6b01fSNick Piggin nd->seq = seq; 13985a18fff2SAl Viro 139924643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14004ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14015a18fff2SAl Viro if (unlikely(status <= 0)) { 14025a18fff2SAl Viro if (status != -ECHILD) 14035a18fff2SAl Viro need_reval = 0; 14045a18fff2SAl Viro goto unlazy; 14055a18fff2SAl Viro } 140624643087SAl Viro } 140731e6b01fSNick Piggin path->mnt = mnt; 140831e6b01fSNick Piggin path->dentry = dentry; 1409d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1410d6e9bd25SAl Viro goto unlazy; 1411d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1412d6e9bd25SAl Viro goto unlazy; 14139875cf80SDavid Howells return 0; 14145a18fff2SAl Viro unlazy: 141519660af7SAl Viro if (unlazy_walk(nd, dentry)) 14165a18fff2SAl Viro return -ECHILD; 14175a18fff2SAl Viro } else { 1418e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 141924643087SAl Viro } 14205a18fff2SAl Viro 142181e6f520SAl Viro if (unlikely(!dentry)) 142281e6f520SAl Viro goto need_lookup; 14235a18fff2SAl Viro 14245a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14254ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14265a18fff2SAl Viro if (unlikely(status <= 0)) { 14275a18fff2SAl Viro if (status < 0) { 14285a18fff2SAl Viro dput(dentry); 14295a18fff2SAl Viro return status; 14305a18fff2SAl Viro } 14315a18fff2SAl Viro if (!d_invalidate(dentry)) { 14325a18fff2SAl Viro dput(dentry); 143381e6f520SAl Viro goto need_lookup; 14345a18fff2SAl Viro } 14355a18fff2SAl Viro } 1436697f514dSMiklos Szeredi 14371da177e4SLinus Torvalds path->mnt = mnt; 14381da177e4SLinus Torvalds path->dentry = dentry; 14399875cf80SDavid Howells err = follow_managed(path, nd->flags); 144089312214SIan Kent if (unlikely(err < 0)) { 144189312214SIan Kent path_put_conditional(path, nd); 14429875cf80SDavid Howells return err; 144389312214SIan Kent } 1444a3fbbde7SAl Viro if (err) 1445a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 144631e6b01fSNick Piggin *inode = path->dentry->d_inode; 14471da177e4SLinus Torvalds return 0; 144881e6f520SAl Viro 144981e6f520SAl Viro need_lookup: 1450697f514dSMiklos Szeredi return 1; 1451697f514dSMiklos Szeredi } 1452697f514dSMiklos Szeredi 1453697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1454cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1455697f514dSMiklos Szeredi { 1456697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1457697f514dSMiklos Szeredi int err; 1458697f514dSMiklos Szeredi 1459697f514dSMiklos Szeredi parent = nd->path.dentry; 146081e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 146181e6f520SAl Viro 146281e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1463cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 146481e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 146581e6f520SAl Viro if (IS_ERR(dentry)) 146681e6f520SAl Viro return PTR_ERR(dentry); 1467697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1468697f514dSMiklos Szeredi path->dentry = dentry; 1469697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1470697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1471697f514dSMiklos Szeredi path_put_conditional(path, nd); 1472697f514dSMiklos Szeredi return err; 1473697f514dSMiklos Szeredi } 1474697f514dSMiklos Szeredi if (err) 1475697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1476697f514dSMiklos Szeredi return 0; 14771da177e4SLinus Torvalds } 14781da177e4SLinus Torvalds 147952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 148052094c8aSAl Viro { 148152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14824ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 148352094c8aSAl Viro if (err != -ECHILD) 148452094c8aSAl Viro return err; 148519660af7SAl Viro if (unlazy_walk(nd, NULL)) 148652094c8aSAl Viro return -ECHILD; 148752094c8aSAl Viro } 14884ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 148952094c8aSAl Viro } 149052094c8aSAl Viro 14919856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 14929856fa1bSAl Viro { 14939856fa1bSAl Viro if (type == LAST_DOTDOT) { 14949856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 14959856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 14969856fa1bSAl Viro return -ECHILD; 14979856fa1bSAl Viro } else 14989856fa1bSAl Viro follow_dotdot(nd); 14999856fa1bSAl Viro } 15009856fa1bSAl Viro return 0; 15019856fa1bSAl Viro } 15029856fa1bSAl Viro 1503951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1504951361f9SAl Viro { 1505951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1506951361f9SAl Viro path_put(&nd->path); 1507951361f9SAl Viro } else { 1508951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15095b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1510951361f9SAl Viro nd->root.mnt = NULL; 151132a7991bSAl Viro unlock_rcu_walk(); 1512951361f9SAl Viro } 1513951361f9SAl Viro } 1514951361f9SAl Viro 15153ddcd056SLinus Torvalds /* 15163ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15173ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15183ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15193ddcd056SLinus Torvalds * for the common case. 15203ddcd056SLinus Torvalds */ 15217813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 15223ddcd056SLinus Torvalds { 15233ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 15243ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 15253ddcd056SLinus Torvalds return follow; 15263ddcd056SLinus Torvalds 15273ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 15283ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 15293ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 15303ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 15313ddcd056SLinus Torvalds } 15323ddcd056SLinus Torvalds return 0; 15333ddcd056SLinus Torvalds } 15343ddcd056SLinus Torvalds 1535ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 153621b9b073SAl Viro int follow) 1537ce57dfc1SAl Viro { 1538ce57dfc1SAl Viro struct inode *inode; 1539ce57dfc1SAl Viro int err; 1540ce57dfc1SAl Viro /* 1541ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1542ce57dfc1SAl Viro * to be able to know about the current root directory and 1543ce57dfc1SAl Viro * parent relationships. 1544ce57dfc1SAl Viro */ 154521b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 154621b9b073SAl Viro return handle_dots(nd, nd->last_type); 1547e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1548ce57dfc1SAl Viro if (unlikely(err)) { 1549697f514dSMiklos Szeredi if (err < 0) 1550697f514dSMiklos Szeredi goto out_err; 1551697f514dSMiklos Szeredi 1552cc2a5271SAl Viro err = lookup_slow(nd, path); 1553697f514dSMiklos Szeredi if (err < 0) 1554697f514dSMiklos Szeredi goto out_err; 1555697f514dSMiklos Szeredi 1556697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1557ce57dfc1SAl Viro } 1558697f514dSMiklos Szeredi err = -ENOENT; 1559697f514dSMiklos Szeredi if (!inode) 1560697f514dSMiklos Szeredi goto out_path_put; 1561697f514dSMiklos Szeredi 15627813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 156319660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 156419660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1565697f514dSMiklos Szeredi err = -ECHILD; 1566697f514dSMiklos Szeredi goto out_err; 156719660af7SAl Viro } 156819660af7SAl Viro } 1569ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1570ce57dfc1SAl Viro return 1; 1571ce57dfc1SAl Viro } 1572ce57dfc1SAl Viro path_to_nameidata(path, nd); 1573ce57dfc1SAl Viro nd->inode = inode; 1574ce57dfc1SAl Viro return 0; 1575697f514dSMiklos Szeredi 1576697f514dSMiklos Szeredi out_path_put: 1577697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1578697f514dSMiklos Szeredi out_err: 1579697f514dSMiklos Szeredi terminate_walk(nd); 1580697f514dSMiklos Szeredi return err; 1581ce57dfc1SAl Viro } 1582ce57dfc1SAl Viro 15831da177e4SLinus Torvalds /* 1584b356379aSAl Viro * This limits recursive symlink follows to 8, while 1585b356379aSAl Viro * limiting consecutive symlinks to 40. 1586b356379aSAl Viro * 1587b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1588b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1589b356379aSAl Viro */ 1590b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1591b356379aSAl Viro { 1592b356379aSAl Viro int res; 1593b356379aSAl Viro 1594b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1595b356379aSAl Viro path_put_conditional(path, nd); 1596b356379aSAl Viro path_put(&nd->path); 1597b356379aSAl Viro return -ELOOP; 1598b356379aSAl Viro } 15991a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1600b356379aSAl Viro 1601b356379aSAl Viro nd->depth++; 1602b356379aSAl Viro current->link_count++; 1603b356379aSAl Viro 1604b356379aSAl Viro do { 1605b356379aSAl Viro struct path link = *path; 1606b356379aSAl Viro void *cookie; 1607574197e0SAl Viro 1608574197e0SAl Viro res = follow_link(&link, nd, &cookie); 16096d7b5aaeSAl Viro if (res) 16106d7b5aaeSAl Viro break; 161121b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1612574197e0SAl Viro put_link(nd, &link, cookie); 1613b356379aSAl Viro } while (res > 0); 1614b356379aSAl Viro 1615b356379aSAl Viro current->link_count--; 1616b356379aSAl Viro nd->depth--; 1617b356379aSAl Viro return res; 1618b356379aSAl Viro } 1619b356379aSAl Viro 1620b356379aSAl Viro /* 16213ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 16223ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 16233ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 16243ddcd056SLinus Torvalds * do lookup on this inode". 16253ddcd056SLinus Torvalds */ 16263ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 16273ddcd056SLinus Torvalds { 16283ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 16293ddcd056SLinus Torvalds return 1; 16303ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 16313ddcd056SLinus Torvalds return 0; 16323ddcd056SLinus Torvalds 16333ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 16343ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 16353ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 16363ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 16373ddcd056SLinus Torvalds return 1; 16383ddcd056SLinus Torvalds } 16393ddcd056SLinus Torvalds 1640bfcfaa77SLinus Torvalds /* 1641bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1642bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1643bfcfaa77SLinus Torvalds * 1644bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1645bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1646bfcfaa77SLinus Torvalds * fast. 1647bfcfaa77SLinus Torvalds * 1648bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1649bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1650bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1651bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1652bfcfaa77SLinus Torvalds * 1653bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1654bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1655bfcfaa77SLinus Torvalds * crossing operation. 1656bfcfaa77SLinus Torvalds * 1657bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1658bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1659bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1660bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1661bfcfaa77SLinus Torvalds */ 1662bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1663bfcfaa77SLinus Torvalds 1664f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1665bfcfaa77SLinus Torvalds 1666f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1667bfcfaa77SLinus Torvalds 1668bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1669bfcfaa77SLinus Torvalds { 1670bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1671bfcfaa77SLinus Torvalds return hash; 1672bfcfaa77SLinus Torvalds } 1673bfcfaa77SLinus Torvalds 1674bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1675bfcfaa77SLinus Torvalds 1676bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1677bfcfaa77SLinus Torvalds 1678bfcfaa77SLinus Torvalds #endif 1679bfcfaa77SLinus Torvalds 1680bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1681bfcfaa77SLinus Torvalds { 1682bfcfaa77SLinus Torvalds unsigned long a, mask; 1683bfcfaa77SLinus Torvalds unsigned long hash = 0; 1684bfcfaa77SLinus Torvalds 1685bfcfaa77SLinus Torvalds for (;;) { 1686e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1687bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1688bfcfaa77SLinus Torvalds break; 1689bfcfaa77SLinus Torvalds hash += a; 1690f132c5beSAl Viro hash *= 9; 1691bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1692bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1693bfcfaa77SLinus Torvalds if (!len) 1694bfcfaa77SLinus Torvalds goto done; 1695bfcfaa77SLinus Torvalds } 1696bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1697bfcfaa77SLinus Torvalds hash += mask & a; 1698bfcfaa77SLinus Torvalds done: 1699bfcfaa77SLinus Torvalds return fold_hash(hash); 1700bfcfaa77SLinus Torvalds } 1701bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1702bfcfaa77SLinus Torvalds 1703bfcfaa77SLinus Torvalds /* 1704bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1705bfcfaa77SLinus Torvalds * return the length of the component; 1706bfcfaa77SLinus Torvalds */ 1707bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1708bfcfaa77SLinus Torvalds { 170936126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 171036126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1711bfcfaa77SLinus Torvalds 1712bfcfaa77SLinus Torvalds hash = a = 0; 1713bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1714bfcfaa77SLinus Torvalds do { 1715bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1716bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1717e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 171836126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 171936126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1720bfcfaa77SLinus Torvalds 172136126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 172236126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172336126f8fSLinus Torvalds 172436126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 172536126f8fSLinus Torvalds 172636126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1727bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1728bfcfaa77SLinus Torvalds 172936126f8fSLinus Torvalds return len + find_zero(mask); 1730bfcfaa77SLinus Torvalds } 1731bfcfaa77SLinus Torvalds 1732bfcfaa77SLinus Torvalds #else 1733bfcfaa77SLinus Torvalds 17340145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17350145acc2SLinus Torvalds { 17360145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17370145acc2SLinus Torvalds while (len--) 17380145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17390145acc2SLinus Torvalds return end_name_hash(hash); 17400145acc2SLinus Torvalds } 1741ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17420145acc2SLinus Torvalds 17433ddcd056SLinus Torvalds /* 1744200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1745200e9ef7SLinus Torvalds * one character. 1746200e9ef7SLinus Torvalds */ 1747200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1748200e9ef7SLinus Torvalds { 1749200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1750200e9ef7SLinus Torvalds unsigned long len = 0, c; 1751200e9ef7SLinus Torvalds 1752200e9ef7SLinus Torvalds c = (unsigned char)*name; 1753200e9ef7SLinus Torvalds do { 1754200e9ef7SLinus Torvalds len++; 1755200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1756200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1757200e9ef7SLinus Torvalds } while (c && c != '/'); 1758200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1759200e9ef7SLinus Torvalds return len; 1760200e9ef7SLinus Torvalds } 1761200e9ef7SLinus Torvalds 1762bfcfaa77SLinus Torvalds #endif 1763bfcfaa77SLinus Torvalds 1764200e9ef7SLinus Torvalds /* 17651da177e4SLinus Torvalds * Name resolution. 1766ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1767ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17681da177e4SLinus Torvalds * 1769ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1770ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17711da177e4SLinus Torvalds */ 17726de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17731da177e4SLinus Torvalds { 17741da177e4SLinus Torvalds struct path next; 17751da177e4SLinus Torvalds int err; 17761da177e4SLinus Torvalds 17771da177e4SLinus Torvalds while (*name=='/') 17781da177e4SLinus Torvalds name++; 17791da177e4SLinus Torvalds if (!*name) 1780086e183aSAl Viro return 0; 17811da177e4SLinus Torvalds 17821da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17831da177e4SLinus Torvalds for(;;) { 17841da177e4SLinus Torvalds struct qstr this; 1785200e9ef7SLinus Torvalds long len; 1786fe479a58SAl Viro int type; 17871da177e4SLinus Torvalds 178852094c8aSAl Viro err = may_lookup(nd); 17891da177e4SLinus Torvalds if (err) 17901da177e4SLinus Torvalds break; 17911da177e4SLinus Torvalds 1792200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 17931da177e4SLinus Torvalds this.name = name; 1794200e9ef7SLinus Torvalds this.len = len; 17951da177e4SLinus Torvalds 1796fe479a58SAl Viro type = LAST_NORM; 1797200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1798fe479a58SAl Viro case 2: 1799200e9ef7SLinus Torvalds if (name[1] == '.') { 1800fe479a58SAl Viro type = LAST_DOTDOT; 180116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 180216c2cd71SAl Viro } 1803fe479a58SAl Viro break; 1804fe479a58SAl Viro case 1: 1805fe479a58SAl Viro type = LAST_DOT; 1806fe479a58SAl Viro } 18075a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18085a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18105a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1811da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18125a202bcdSAl Viro if (err < 0) 18135a202bcdSAl Viro break; 18145a202bcdSAl Viro } 18155a202bcdSAl Viro } 1816fe479a58SAl Viro 18175f4a6a69SAl Viro nd->last = this; 18185f4a6a69SAl Viro nd->last_type = type; 18195f4a6a69SAl Viro 1820200e9ef7SLinus Torvalds if (!name[len]) 18215f4a6a69SAl Viro return 0; 1822200e9ef7SLinus Torvalds /* 1823200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1824200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1825200e9ef7SLinus Torvalds */ 1826200e9ef7SLinus Torvalds do { 1827200e9ef7SLinus Torvalds len++; 1828200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1829200e9ef7SLinus Torvalds if (!name[len]) 18305f4a6a69SAl Viro return 0; 18315f4a6a69SAl Viro 1832200e9ef7SLinus Torvalds name += len; 18331da177e4SLinus Torvalds 183421b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1835ce57dfc1SAl Viro if (err < 0) 1836ce57dfc1SAl Viro return err; 1837fe479a58SAl Viro 1838ce57dfc1SAl Viro if (err) { 1839b356379aSAl Viro err = nested_symlink(&next, nd); 18401da177e4SLinus Torvalds if (err) 1841a7472babSAl Viro return err; 184231e6b01fSNick Piggin } 18435f4a6a69SAl Viro if (!can_lookup(nd->inode)) { 18443ddcd056SLinus Torvalds err = -ENOTDIR; 18453ddcd056SLinus Torvalds break; 18465f4a6a69SAl Viro } 1847ce57dfc1SAl Viro } 1848951361f9SAl Viro terminate_walk(nd); 18491da177e4SLinus Torvalds return err; 18501da177e4SLinus Torvalds } 18511da177e4SLinus Torvalds 185270e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 185370e9b357SAl Viro struct nameidata *nd, struct file **fp) 185431e6b01fSNick Piggin { 185531e6b01fSNick Piggin int retval = 0; 185631e6b01fSNick Piggin 185731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 185816c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 185931e6b01fSNick Piggin nd->depth = 0; 18605b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 18615b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 186273d049a4SAl Viro if (*name) { 1863741b7c3fSAl Viro if (!can_lookup(inode)) 18645b6ca027SAl Viro return -ENOTDIR; 18655b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18665b6ca027SAl Viro if (retval) 18675b6ca027SAl Viro return retval; 186873d049a4SAl Viro } 18695b6ca027SAl Viro nd->path = nd->root; 18705b6ca027SAl Viro nd->inode = inode; 18715b6ca027SAl Viro if (flags & LOOKUP_RCU) { 187232a7991bSAl Viro lock_rcu_walk(); 18735b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 18745b6ca027SAl Viro } else { 18755b6ca027SAl Viro path_get(&nd->path); 18765b6ca027SAl Viro } 18775b6ca027SAl Viro return 0; 18785b6ca027SAl Viro } 18795b6ca027SAl Viro 188031e6b01fSNick Piggin nd->root.mnt = NULL; 188131e6b01fSNick Piggin 188231e6b01fSNick Piggin if (*name=='/') { 1883e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 188432a7991bSAl Viro lock_rcu_walk(); 1885e41f7d4eSAl Viro set_root_rcu(nd); 1886e41f7d4eSAl Viro } else { 1887e41f7d4eSAl Viro set_root(nd); 1888e41f7d4eSAl Viro path_get(&nd->root); 1889e41f7d4eSAl Viro } 189031e6b01fSNick Piggin nd->path = nd->root; 189131e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1892e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 189331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1894c28cc364SNick Piggin unsigned seq; 189531e6b01fSNick Piggin 189632a7991bSAl Viro lock_rcu_walk(); 189731e6b01fSNick Piggin 1898c28cc364SNick Piggin do { 1899c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 190031e6b01fSNick Piggin nd->path = fs->pwd; 1901c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1902c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1903e41f7d4eSAl Viro } else { 1904e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1905e41f7d4eSAl Viro } 190631e6b01fSNick Piggin } else { 1907582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19082903ff01SAl Viro struct fd f = fdget_raw(dfd); 190931e6b01fSNick Piggin struct dentry *dentry; 191031e6b01fSNick Piggin 19112903ff01SAl Viro if (!f.file) 19122903ff01SAl Viro return -EBADF; 191331e6b01fSNick Piggin 19142903ff01SAl Viro dentry = f.file->f_path.dentry; 191531e6b01fSNick Piggin 1916f52e0c11SAl Viro if (*name) { 1917741b7c3fSAl Viro if (!can_lookup(dentry->d_inode)) { 19182903ff01SAl Viro fdput(f); 19192903ff01SAl Viro return -ENOTDIR; 1920f52e0c11SAl Viro } 19212903ff01SAl Viro } 19222903ff01SAl Viro 19232903ff01SAl Viro nd->path = f.file->f_path; 1924e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19252903ff01SAl Viro if (f.need_put) 19262903ff01SAl Viro *fp = f.file; 1927c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 192832a7991bSAl Viro lock_rcu_walk(); 19295590ff0dSUlrich Drepper } else { 19302903ff01SAl Viro path_get(&nd->path); 19312903ff01SAl Viro fdput(f); 19321da177e4SLinus Torvalds } 1933e41f7d4eSAl Viro } 1934e41f7d4eSAl Viro 193531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19369b4a9b14SAl Viro return 0; 19379b4a9b14SAl Viro } 19389b4a9b14SAl Viro 1939bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1940bd92d7feSAl Viro { 1941bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1942bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1943bd92d7feSAl Viro 1944bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 194521b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1946bd92d7feSAl Viro } 1947bd92d7feSAl Viro 19489b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1949ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19509b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19519b4a9b14SAl Viro { 195270e9b357SAl Viro struct file *base = NULL; 1953bd92d7feSAl Viro struct path path; 1954bd92d7feSAl Viro int err; 195531e6b01fSNick Piggin 195631e6b01fSNick Piggin /* 195731e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 195831e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 195931e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 196031e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 196131e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 196231e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 196331e6b01fSNick Piggin * analogue, foo_rcu(). 196431e6b01fSNick Piggin * 196531e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 196631e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 196731e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 196831e6b01fSNick Piggin * be able to complete). 196931e6b01fSNick Piggin */ 1970bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1971ee0827cdSAl Viro 1972bd92d7feSAl Viro if (unlikely(err)) 1973bd92d7feSAl Viro return err; 1974ee0827cdSAl Viro 1975ee0827cdSAl Viro current->total_link_count = 0; 1976bd92d7feSAl Viro err = link_path_walk(name, nd); 1977bd92d7feSAl Viro 1978bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1979bd92d7feSAl Viro err = lookup_last(nd, &path); 1980bd92d7feSAl Viro while (err > 0) { 1981bd92d7feSAl Viro void *cookie; 1982bd92d7feSAl Viro struct path link = path; 1983800179c9SKees Cook err = may_follow_link(&link, nd); 1984800179c9SKees Cook if (unlikely(err)) 1985800179c9SKees Cook break; 1986bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1987574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19886d7b5aaeSAl Viro if (err) 19896d7b5aaeSAl Viro break; 1990bd92d7feSAl Viro err = lookup_last(nd, &path); 1991574197e0SAl Viro put_link(nd, &link, cookie); 1992bd92d7feSAl Viro } 1993bd92d7feSAl Viro } 1994ee0827cdSAl Viro 19959f1fafeeSAl Viro if (!err) 19969f1fafeeSAl Viro err = complete_walk(nd); 1997bd92d7feSAl Viro 1998bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 199905252901SAl Viro if (!can_lookup(nd->inode)) { 2000bd92d7feSAl Viro path_put(&nd->path); 2001bd23a539SAl Viro err = -ENOTDIR; 2002bd92d7feSAl Viro } 2003bd92d7feSAl Viro } 200416c2cd71SAl Viro 200570e9b357SAl Viro if (base) 200670e9b357SAl Viro fput(base); 2007ee0827cdSAl Viro 20085b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 200931e6b01fSNick Piggin path_put(&nd->root); 201031e6b01fSNick Piggin nd->root.mnt = NULL; 201131e6b01fSNick Piggin } 2012bd92d7feSAl Viro return err; 201331e6b01fSNick Piggin } 201431e6b01fSNick Piggin 2015873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2016873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2017873f1eedSJeff Layton { 2018873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 2019873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2020873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 2021873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2022873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 2023873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 2024873f1eedSJeff Layton 2025873f1eedSJeff Layton if (likely(!retval)) 2026adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2027873f1eedSJeff Layton return retval; 2028873f1eedSJeff Layton } 2029873f1eedSJeff Layton 2030ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 2031ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 2032ee0827cdSAl Viro { 2033873f1eedSJeff Layton struct filename filename = { .name = name }; 2034ee0827cdSAl Viro 2035873f1eedSJeff Layton return filename_lookup(dfd, &filename, flags, nd); 20361da177e4SLinus Torvalds } 20371da177e4SLinus Torvalds 203879714f72SAl Viro /* does lookup, returns the object with parent locked */ 203979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20405590ff0dSUlrich Drepper { 204179714f72SAl Viro struct nameidata nd; 204279714f72SAl Viro struct dentry *d; 204379714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 204479714f72SAl Viro if (err) 204579714f72SAl Viro return ERR_PTR(err); 204679714f72SAl Viro if (nd.last_type != LAST_NORM) { 204779714f72SAl Viro path_put(&nd.path); 204879714f72SAl Viro return ERR_PTR(-EINVAL); 204979714f72SAl Viro } 205079714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20511e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 205279714f72SAl Viro if (IS_ERR(d)) { 205379714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 205479714f72SAl Viro path_put(&nd.path); 205579714f72SAl Viro return d; 205679714f72SAl Viro } 205779714f72SAl Viro *path = nd.path; 205879714f72SAl Viro return d; 20595590ff0dSUlrich Drepper } 20605590ff0dSUlrich Drepper 2061d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2062d1811465SAl Viro { 2063d1811465SAl Viro struct nameidata nd; 2064d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2065d1811465SAl Viro if (!res) 2066d1811465SAl Viro *path = nd.path; 2067d1811465SAl Viro return res; 2068d1811465SAl Viro } 2069d1811465SAl Viro 207016f18200SJosef 'Jeff' Sipek /** 207116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 207216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 207316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 207416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 207516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2076e0a01249SAl Viro * @path: pointer to struct path to fill 207716f18200SJosef 'Jeff' Sipek */ 207816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 207916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2080e0a01249SAl Viro struct path *path) 208116f18200SJosef 'Jeff' Sipek { 2082e0a01249SAl Viro struct nameidata nd; 2083e0a01249SAl Viro int err; 2084e0a01249SAl Viro nd.root.dentry = dentry; 2085e0a01249SAl Viro nd.root.mnt = mnt; 2086e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20875b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2088e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2089e0a01249SAl Viro if (!err) 2090e0a01249SAl Viro *path = nd.path; 2091e0a01249SAl Viro return err; 209216f18200SJosef 'Jeff' Sipek } 209316f18200SJosef 'Jeff' Sipek 2094057f6c01SJames Morris /* 2095057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2096057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2097057f6c01SJames Morris * SMP-safe. 2098057f6c01SJames Morris */ 2099a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 21001da177e4SLinus Torvalds { 210172bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 21021da177e4SLinus Torvalds } 21031da177e4SLinus Torvalds 2104eead1911SChristoph Hellwig /** 2105a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2106eead1911SChristoph Hellwig * @name: pathname component to lookup 2107eead1911SChristoph Hellwig * @base: base directory to lookup from 2108eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2109eead1911SChristoph Hellwig * 2110a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2111a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2112eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2113eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2114eead1911SChristoph Hellwig */ 2115057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2116057f6c01SJames Morris { 2117057f6c01SJames Morris struct qstr this; 21186a96ba54SAl Viro unsigned int c; 2119cda309deSMiklos Szeredi int err; 2120057f6c01SJames Morris 21212f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21222f9092e1SDavid Woodhouse 21236a96ba54SAl Viro this.name = name; 21246a96ba54SAl Viro this.len = len; 21250145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21266a96ba54SAl Viro if (!len) 21276a96ba54SAl Viro return ERR_PTR(-EACCES); 21286a96ba54SAl Viro 212921d8a15aSAl Viro if (unlikely(name[0] == '.')) { 213021d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 213121d8a15aSAl Viro return ERR_PTR(-EACCES); 213221d8a15aSAl Viro } 213321d8a15aSAl Viro 21346a96ba54SAl Viro while (len--) { 21356a96ba54SAl Viro c = *(const unsigned char *)name++; 21366a96ba54SAl Viro if (c == '/' || c == '\0') 21376a96ba54SAl Viro return ERR_PTR(-EACCES); 21386a96ba54SAl Viro } 21395a202bcdSAl Viro /* 21405a202bcdSAl Viro * See if the low-level filesystem might want 21415a202bcdSAl Viro * to use its own hash.. 21425a202bcdSAl Viro */ 21435a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2144da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21455a202bcdSAl Viro if (err < 0) 21465a202bcdSAl Viro return ERR_PTR(err); 21475a202bcdSAl Viro } 2148eead1911SChristoph Hellwig 2149cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2150cda309deSMiklos Szeredi if (err) 2151cda309deSMiklos Szeredi return ERR_PTR(err); 2152cda309deSMiklos Szeredi 215372bd866aSAl Viro return __lookup_hash(&this, base, 0); 2154057f6c01SJames Morris } 2155057f6c01SJames Morris 21561fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21571fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21581da177e4SLinus Torvalds { 21592d8f3038SAl Viro struct nameidata nd; 216091a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21611da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21621da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21632d8f3038SAl Viro 21642d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21652d8f3038SAl Viro 2166873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21671da177e4SLinus Torvalds putname(tmp); 21682d8f3038SAl Viro if (!err) 21692d8f3038SAl Viro *path = nd.path; 21701da177e4SLinus Torvalds } 21711da177e4SLinus Torvalds return err; 21721da177e4SLinus Torvalds } 21731da177e4SLinus Torvalds 21741fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21751fa1e7f6SAndy Whitcroft struct path *path) 21761fa1e7f6SAndy Whitcroft { 2177f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21781fa1e7f6SAndy Whitcroft } 21791fa1e7f6SAndy Whitcroft 2180873f1eedSJeff Layton /* 2181873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2182873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2183873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2184873f1eedSJeff Layton * path-walking is complete. 2185873f1eedSJeff Layton */ 218691a27b2aSJeff Layton static struct filename * 21879e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 21889e790bd6SJeff Layton unsigned int flags) 21892ad94ae6SAl Viro { 219091a27b2aSJeff Layton struct filename *s = getname(path); 21912ad94ae6SAl Viro int error; 21922ad94ae6SAl Viro 21939e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 21949e790bd6SJeff Layton flags &= LOOKUP_REVAL; 21959e790bd6SJeff Layton 21962ad94ae6SAl Viro if (IS_ERR(s)) 219791a27b2aSJeff Layton return s; 21982ad94ae6SAl Viro 21999e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 220091a27b2aSJeff Layton if (error) { 22012ad94ae6SAl Viro putname(s); 220291a27b2aSJeff Layton return ERR_PTR(error); 220391a27b2aSJeff Layton } 22042ad94ae6SAl Viro 220591a27b2aSJeff Layton return s; 22062ad94ae6SAl Viro } 22072ad94ae6SAl Viro 22088033426eSJeff Layton /** 22098033426eSJeff Layton * umount_lookup_last - look up last component for umount 22108033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22118033426eSJeff Layton * @path: pointer to container for result 22128033426eSJeff Layton * 22138033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22148033426eSJeff Layton * need to resolve the path without doing any revalidation. 22158033426eSJeff Layton * 22168033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22178033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22188033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22198033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22208033426eSJeff Layton * bogus and it doesn't exist. 22218033426eSJeff Layton * 22228033426eSJeff Layton * Returns: 22238033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22248033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22258033426eSJeff Layton * put in this case. 22268033426eSJeff Layton * 22278033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22288033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22298033426eSJeff Layton * The nd->path reference will also be put. 22308033426eSJeff Layton * 22318033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22328033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22338033426eSJeff Layton * to the link, and nd->path will *not* be put. 22348033426eSJeff Layton */ 22358033426eSJeff Layton static int 22368033426eSJeff Layton umount_lookup_last(struct nameidata *nd, struct path *path) 22378033426eSJeff Layton { 22388033426eSJeff Layton int error = 0; 22398033426eSJeff Layton struct dentry *dentry; 22408033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22418033426eSJeff Layton 22428033426eSJeff Layton if (unlikely(nd->flags & LOOKUP_RCU)) { 22438033426eSJeff Layton WARN_ON_ONCE(1); 22448033426eSJeff Layton error = -ECHILD; 22458033426eSJeff Layton goto error_check; 22468033426eSJeff Layton } 22478033426eSJeff Layton 22488033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22498033426eSJeff Layton 22508033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22518033426eSJeff Layton error = handle_dots(nd, nd->last_type); 22528033426eSJeff Layton if (!error) 22538033426eSJeff Layton dentry = dget(nd->path.dentry); 22548033426eSJeff Layton goto error_check; 22558033426eSJeff Layton } 22568033426eSJeff Layton 22578033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22588033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22598033426eSJeff Layton if (!dentry) { 22608033426eSJeff Layton /* 22618033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22628033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22638033426eSJeff Layton * path doesn't actually point to a mounted dentry. 22648033426eSJeff Layton */ 22658033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22668033426eSJeff Layton if (!dentry) { 22678033426eSJeff Layton error = -ENOMEM; 22688033426eSJeff Layton } else { 22698033426eSJeff Layton dentry = lookup_real(dir->d_inode, dentry, nd->flags); 22708033426eSJeff Layton if (IS_ERR(dentry)) 22718033426eSJeff Layton error = PTR_ERR(dentry); 22728033426eSJeff Layton } 22738033426eSJeff Layton } 22748033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 22758033426eSJeff Layton 22768033426eSJeff Layton error_check: 22778033426eSJeff Layton if (!error) { 22788033426eSJeff Layton if (!dentry->d_inode) { 22798033426eSJeff Layton error = -ENOENT; 22808033426eSJeff Layton dput(dentry); 22818033426eSJeff Layton } else { 22828033426eSJeff Layton path->dentry = dentry; 22838033426eSJeff Layton path->mnt = mntget(nd->path.mnt); 22848033426eSJeff Layton if (should_follow_link(dentry->d_inode, 22858033426eSJeff Layton nd->flags & LOOKUP_FOLLOW)) 22868033426eSJeff Layton return 1; 22878033426eSJeff Layton follow_mount(path); 22888033426eSJeff Layton } 22898033426eSJeff Layton } 22908033426eSJeff Layton terminate_walk(nd); 22918033426eSJeff Layton return error; 22928033426eSJeff Layton } 22938033426eSJeff Layton 22948033426eSJeff Layton /** 22958033426eSJeff Layton * path_umountat - look up a path to be umounted 22968033426eSJeff Layton * @dfd: directory file descriptor to start walk from 22978033426eSJeff Layton * @name: full pathname to walk 22988033426eSJeff Layton * @flags: lookup flags 22998033426eSJeff Layton * @nd: pathwalk nameidata 23008033426eSJeff Layton * 23018033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 23028033426eSJeff Layton * Returns 0 and "path" will be valid on success; Retuns error otherwise. 23038033426eSJeff Layton */ 23048033426eSJeff Layton static int 23058033426eSJeff Layton path_umountat(int dfd, const char *name, struct path *path, unsigned int flags) 23068033426eSJeff Layton { 23078033426eSJeff Layton struct file *base = NULL; 23088033426eSJeff Layton struct nameidata nd; 23098033426eSJeff Layton int err; 23108033426eSJeff Layton 23118033426eSJeff Layton err = path_init(dfd, name, flags | LOOKUP_PARENT, &nd, &base); 23128033426eSJeff Layton if (unlikely(err)) 23138033426eSJeff Layton return err; 23148033426eSJeff Layton 23158033426eSJeff Layton current->total_link_count = 0; 23168033426eSJeff Layton err = link_path_walk(name, &nd); 23178033426eSJeff Layton if (err) 23188033426eSJeff Layton goto out; 23198033426eSJeff Layton 23208033426eSJeff Layton /* If we're in rcuwalk, drop out of it to handle last component */ 23218033426eSJeff Layton if (nd.flags & LOOKUP_RCU) { 23228033426eSJeff Layton err = unlazy_walk(&nd, NULL); 23238033426eSJeff Layton if (err) { 23248033426eSJeff Layton terminate_walk(&nd); 23258033426eSJeff Layton goto out; 23268033426eSJeff Layton } 23278033426eSJeff Layton } 23288033426eSJeff Layton 23298033426eSJeff Layton err = umount_lookup_last(&nd, path); 23308033426eSJeff Layton while (err > 0) { 23318033426eSJeff Layton void *cookie; 23328033426eSJeff Layton struct path link = *path; 23338033426eSJeff Layton err = may_follow_link(&link, &nd); 23348033426eSJeff Layton if (unlikely(err)) 23358033426eSJeff Layton break; 23368033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 23378033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 23388033426eSJeff Layton if (err) 23398033426eSJeff Layton break; 23408033426eSJeff Layton err = umount_lookup_last(&nd, path); 23418033426eSJeff Layton put_link(&nd, &link, cookie); 23428033426eSJeff Layton } 23438033426eSJeff Layton out: 23448033426eSJeff Layton if (base) 23458033426eSJeff Layton fput(base); 23468033426eSJeff Layton 23478033426eSJeff Layton if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT)) 23488033426eSJeff Layton path_put(&nd.root); 23498033426eSJeff Layton 23508033426eSJeff Layton return err; 23518033426eSJeff Layton } 23528033426eSJeff Layton 23538033426eSJeff Layton /** 23548033426eSJeff Layton * user_path_umountat - lookup a path from userland in order to umount it 23558033426eSJeff Layton * @dfd: directory file descriptor 23568033426eSJeff Layton * @name: pathname from userland 23578033426eSJeff Layton * @flags: lookup flags 23588033426eSJeff Layton * @path: pointer to container to hold result 23598033426eSJeff Layton * 23608033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23618033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23628033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23638033426eSJeff Layton * and avoid revalidating the last component. 23648033426eSJeff Layton * 23658033426eSJeff Layton * Returns 0 and populates "path" on success. 23668033426eSJeff Layton */ 23678033426eSJeff Layton int 23688033426eSJeff Layton user_path_umountat(int dfd, const char __user *name, unsigned int flags, 23698033426eSJeff Layton struct path *path) 23708033426eSJeff Layton { 23718033426eSJeff Layton struct filename *s = getname(name); 23728033426eSJeff Layton int error; 23738033426eSJeff Layton 23748033426eSJeff Layton if (IS_ERR(s)) 23758033426eSJeff Layton return PTR_ERR(s); 23768033426eSJeff Layton 23778033426eSJeff Layton error = path_umountat(dfd, s->name, path, flags | LOOKUP_RCU); 23788033426eSJeff Layton if (unlikely(error == -ECHILD)) 23798033426eSJeff Layton error = path_umountat(dfd, s->name, path, flags); 23808033426eSJeff Layton if (unlikely(error == -ESTALE)) 23818033426eSJeff Layton error = path_umountat(dfd, s->name, path, flags | LOOKUP_REVAL); 23828033426eSJeff Layton 23838033426eSJeff Layton if (likely(!error)) 23848033426eSJeff Layton audit_inode(s, path->dentry, 0); 23858033426eSJeff Layton 23868033426eSJeff Layton putname(s); 23878033426eSJeff Layton return error; 23888033426eSJeff Layton } 23898033426eSJeff Layton 23901da177e4SLinus Torvalds /* 23911da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 23921da177e4SLinus Torvalds * minimal. 23931da177e4SLinus Torvalds */ 23941da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 23951da177e4SLinus Torvalds { 23968e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2397da9592edSDavid Howells 23981da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 23991da177e4SLinus Torvalds return 0; 24008e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24011da177e4SLinus Torvalds return 0; 24028e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24031da177e4SLinus Torvalds return 0; 24041a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 24051da177e4SLinus Torvalds } 24061da177e4SLinus Torvalds 24071da177e4SLinus Torvalds /* 24081da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24091da177e4SLinus Torvalds * whether the type of victim is right. 24101da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24111da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24121da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24131da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24141da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24151da177e4SLinus Torvalds * a. be owner of dir, or 24161da177e4SLinus Torvalds * b. be owner of victim, or 24171da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24181da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24191da177e4SLinus Torvalds * links pointing to it. 24201da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24211da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24221da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24231da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24241da177e4SLinus Torvalds * nfs_async_unlink(). 24251da177e4SLinus Torvalds */ 2426858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 24271da177e4SLinus Torvalds { 24281da177e4SLinus Torvalds int error; 24291da177e4SLinus Torvalds 24301da177e4SLinus Torvalds if (!victim->d_inode) 24311da177e4SLinus Torvalds return -ENOENT; 24321da177e4SLinus Torvalds 24331da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24344fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24351da177e4SLinus Torvalds 2436f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24371da177e4SLinus Torvalds if (error) 24381da177e4SLinus Torvalds return error; 24391da177e4SLinus Torvalds if (IS_APPEND(dir)) 24401da177e4SLinus Torvalds return -EPERM; 24411da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2442f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 24431da177e4SLinus Torvalds return -EPERM; 24441da177e4SLinus Torvalds if (isdir) { 24451da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 24461da177e4SLinus Torvalds return -ENOTDIR; 24471da177e4SLinus Torvalds if (IS_ROOT(victim)) 24481da177e4SLinus Torvalds return -EBUSY; 24491da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 24501da177e4SLinus Torvalds return -EISDIR; 24511da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24521da177e4SLinus Torvalds return -ENOENT; 24531da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24541da177e4SLinus Torvalds return -EBUSY; 24551da177e4SLinus Torvalds return 0; 24561da177e4SLinus Torvalds } 24571da177e4SLinus Torvalds 24581da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24591da177e4SLinus Torvalds * dir. 24601da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24611da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24621da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24631da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24641da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24651da177e4SLinus Torvalds */ 2466a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24671da177e4SLinus Torvalds { 24681da177e4SLinus Torvalds if (child->d_inode) 24691da177e4SLinus Torvalds return -EEXIST; 24701da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24711da177e4SLinus Torvalds return -ENOENT; 2472f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24731da177e4SLinus Torvalds } 24741da177e4SLinus Torvalds 24751da177e4SLinus Torvalds /* 24761da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24771da177e4SLinus Torvalds */ 24781da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24791da177e4SLinus Torvalds { 24801da177e4SLinus Torvalds struct dentry *p; 24811da177e4SLinus Torvalds 24821da177e4SLinus Torvalds if (p1 == p2) { 2483f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 24841da177e4SLinus Torvalds return NULL; 24851da177e4SLinus Torvalds } 24861da177e4SLinus Torvalds 2487a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 24881da177e4SLinus Torvalds 2489e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2490e2761a11SOGAWA Hirofumi if (p) { 2491f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2492f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 24931da177e4SLinus Torvalds return p; 24941da177e4SLinus Torvalds } 24951da177e4SLinus Torvalds 2496e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2497e2761a11SOGAWA Hirofumi if (p) { 2498f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2499f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25001da177e4SLinus Torvalds return p; 25011da177e4SLinus Torvalds } 25021da177e4SLinus Torvalds 2503f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2504f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25051da177e4SLinus Torvalds return NULL; 25061da177e4SLinus Torvalds } 25071da177e4SLinus Torvalds 25081da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25091da177e4SLinus Torvalds { 25101b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25111da177e4SLinus Torvalds if (p1 != p2) { 25121b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2513a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25141da177e4SLinus Torvalds } 25151da177e4SLinus Torvalds } 25161da177e4SLinus Torvalds 25174acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2518312b63fbSAl Viro bool want_excl) 25191da177e4SLinus Torvalds { 2520a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25211da177e4SLinus Torvalds if (error) 25221da177e4SLinus Torvalds return error; 25231da177e4SLinus Torvalds 2524acfa4380SAl Viro if (!dir->i_op->create) 25251da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25261da177e4SLinus Torvalds mode &= S_IALLUGO; 25271da177e4SLinus Torvalds mode |= S_IFREG; 25281da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25291da177e4SLinus Torvalds if (error) 25301da177e4SLinus Torvalds return error; 2531312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2532a74574aaSStephen Smalley if (!error) 2533f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25341da177e4SLinus Torvalds return error; 25351da177e4SLinus Torvalds } 25361da177e4SLinus Torvalds 253773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25381da177e4SLinus Torvalds { 25393fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25401da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25411da177e4SLinus Torvalds int error; 25421da177e4SLinus Torvalds 2543bcda7652SAl Viro /* O_PATH? */ 2544bcda7652SAl Viro if (!acc_mode) 2545bcda7652SAl Viro return 0; 2546bcda7652SAl Viro 25471da177e4SLinus Torvalds if (!inode) 25481da177e4SLinus Torvalds return -ENOENT; 25491da177e4SLinus Torvalds 2550c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2551c8fe8f30SChristoph Hellwig case S_IFLNK: 25521da177e4SLinus Torvalds return -ELOOP; 2553c8fe8f30SChristoph Hellwig case S_IFDIR: 2554c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25551da177e4SLinus Torvalds return -EISDIR; 2556c8fe8f30SChristoph Hellwig break; 2557c8fe8f30SChristoph Hellwig case S_IFBLK: 2558c8fe8f30SChristoph Hellwig case S_IFCHR: 25593fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25601da177e4SLinus Torvalds return -EACCES; 2561c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2562c8fe8f30SChristoph Hellwig case S_IFIFO: 2563c8fe8f30SChristoph Hellwig case S_IFSOCK: 25641da177e4SLinus Torvalds flag &= ~O_TRUNC; 2565c8fe8f30SChristoph Hellwig break; 25664a3fd211SDave Hansen } 2567b41572e9SDave Hansen 25683fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2569b41572e9SDave Hansen if (error) 2570b41572e9SDave Hansen return error; 25716146f0d5SMimi Zohar 25721da177e4SLinus Torvalds /* 25731da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25741da177e4SLinus Torvalds */ 25751da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25768737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 25777715b521SAl Viro return -EPERM; 25781da177e4SLinus Torvalds if (flag & O_TRUNC) 25797715b521SAl Viro return -EPERM; 25801da177e4SLinus Torvalds } 25811da177e4SLinus Torvalds 25821da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 25832e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 25847715b521SAl Viro return -EPERM; 25851da177e4SLinus Torvalds 2586f3c7691eSJ. Bruce Fields return 0; 25877715b521SAl Viro } 25887715b521SAl Viro 2589e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 25907715b521SAl Viro { 2591e1181ee6SJeff Layton struct path *path = &filp->f_path; 25927715b521SAl Viro struct inode *inode = path->dentry->d_inode; 25937715b521SAl Viro int error = get_write_access(inode); 25941da177e4SLinus Torvalds if (error) 25957715b521SAl Viro return error; 25961da177e4SLinus Torvalds /* 25971da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 25981da177e4SLinus Torvalds */ 25991da177e4SLinus Torvalds error = locks_verify_locked(inode); 2600be6d3e56SKentaro Takeda if (!error) 2601ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26021da177e4SLinus Torvalds if (!error) { 26037715b521SAl Viro error = do_truncate(path->dentry, 0, 2604d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2605e1181ee6SJeff Layton filp); 26061da177e4SLinus Torvalds } 26071da177e4SLinus Torvalds put_write_access(inode); 2608acd0c935SMimi Zohar return error; 26091da177e4SLinus Torvalds } 26101da177e4SLinus Torvalds 2611d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2612d57999e1SDave Hansen { 26138a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26148a5e929dSAl Viro flag--; 2615d57999e1SDave Hansen return flag; 2616d57999e1SDave Hansen } 2617d57999e1SDave Hansen 2618d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2619d18e9008SMiklos Szeredi { 2620d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2621d18e9008SMiklos Szeredi if (error) 2622d18e9008SMiklos Szeredi return error; 2623d18e9008SMiklos Szeredi 2624d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2625d18e9008SMiklos Szeredi if (error) 2626d18e9008SMiklos Szeredi return error; 2627d18e9008SMiklos Szeredi 2628d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2629d18e9008SMiklos Szeredi } 2630d18e9008SMiklos Szeredi 26311acf0af9SDavid Howells /* 26321acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26331acf0af9SDavid Howells * dentry. 26341acf0af9SDavid Howells * 26351acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26361acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26371acf0af9SDavid Howells * 26381acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26391acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26401acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26411acf0af9SDavid Howells * 26421acf0af9SDavid Howells * Returns an error code otherwise. 26431acf0af9SDavid Howells */ 26442675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 264530d90494SAl Viro struct path *path, struct file *file, 2646015c3bbcSMiklos Szeredi const struct open_flags *op, 264764894cf8SAl Viro bool got_write, bool need_lookup, 264847237687SAl Viro int *opened) 2649d18e9008SMiklos Szeredi { 2650d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2651d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2652d18e9008SMiklos Szeredi umode_t mode; 2653d18e9008SMiklos Szeredi int error; 2654d18e9008SMiklos Szeredi int acc_mode; 2655d18e9008SMiklos Szeredi int create_error = 0; 2656d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2657d18e9008SMiklos Szeredi 2658d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2659d18e9008SMiklos Szeredi 2660d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2661d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26622675a4ebSAl Viro error = -ENOENT; 2663d18e9008SMiklos Szeredi goto out; 2664d18e9008SMiklos Szeredi } 2665d18e9008SMiklos Szeredi 266662b259d8SMiklos Szeredi mode = op->mode; 2667d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2668d18e9008SMiklos Szeredi mode &= ~current_umask(); 2669d18e9008SMiklos Szeredi 2670f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) { 2671d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 267247237687SAl Viro *opened |= FILE_CREATED; 2673d18e9008SMiklos Szeredi } 2674d18e9008SMiklos Szeredi 2675d18e9008SMiklos Szeredi /* 2676d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2677d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2678d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2679d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2680d18e9008SMiklos Szeredi * 2681d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2682d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2683d18e9008SMiklos Szeredi */ 268464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 268564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 268664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2687d18e9008SMiklos Szeredi /* 2688d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2689d18e9008SMiklos Szeredi * back to lookup + open 2690d18e9008SMiklos Szeredi */ 2691d18e9008SMiklos Szeredi goto no_open; 2692d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2693d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 269464894cf8SAl Viro create_error = -EROFS; 2695d18e9008SMiklos Szeredi goto no_open; 2696d18e9008SMiklos Szeredi } else { 2697d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 269864894cf8SAl Viro create_error = -EROFS; 2699d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2700d18e9008SMiklos Szeredi } 2701d18e9008SMiklos Szeredi } 2702d18e9008SMiklos Szeredi 2703d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 270438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2705d18e9008SMiklos Szeredi if (error) { 2706d18e9008SMiklos Szeredi create_error = error; 2707d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2708d18e9008SMiklos Szeredi goto no_open; 2709d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2710d18e9008SMiklos Szeredi } 2711d18e9008SMiklos Szeredi } 2712d18e9008SMiklos Szeredi 2713d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2714d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2715d18e9008SMiklos Szeredi 271630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 271730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 271830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 271947237687SAl Viro opened); 2720d9585277SAl Viro if (error < 0) { 2721d9585277SAl Viro if (create_error && error == -ENOENT) 2722d9585277SAl Viro error = create_error; 2723d18e9008SMiklos Szeredi goto out; 2724d18e9008SMiklos Szeredi } 2725d18e9008SMiklos Szeredi 2726d18e9008SMiklos Szeredi acc_mode = op->acc_mode; 272747237687SAl Viro if (*opened & FILE_CREATED) { 2728d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2729d18e9008SMiklos Szeredi acc_mode = MAY_OPEN; 2730d18e9008SMiklos Szeredi } 2731d18e9008SMiklos Szeredi 2732d9585277SAl Viro if (error) { /* returned 1, that is */ 273330d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27342675a4ebSAl Viro error = -EIO; 2735d18e9008SMiklos Szeredi goto out; 2736d18e9008SMiklos Szeredi } 273730d90494SAl Viro if (file->f_path.dentry) { 2738d18e9008SMiklos Szeredi dput(dentry); 273930d90494SAl Viro dentry = file->f_path.dentry; 2740d18e9008SMiklos Szeredi } 274162b2ce96SSage Weil if (create_error && dentry->d_inode == NULL) { 274262b2ce96SSage Weil error = create_error; 274362b2ce96SSage Weil goto out; 274462b2ce96SSage Weil } 2745d18e9008SMiklos Szeredi goto looked_up; 2746d18e9008SMiklos Szeredi } 2747d18e9008SMiklos Szeredi 2748d18e9008SMiklos Szeredi /* 2749d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2750d18e9008SMiklos Szeredi * here. 2751d18e9008SMiklos Szeredi */ 27522675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27532675a4ebSAl Viro if (error) 27542675a4ebSAl Viro fput(file); 2755d18e9008SMiklos Szeredi 2756d18e9008SMiklos Szeredi out: 2757d18e9008SMiklos Szeredi dput(dentry); 27582675a4ebSAl Viro return error; 2759d18e9008SMiklos Szeredi 2760d18e9008SMiklos Szeredi no_open: 2761d18e9008SMiklos Szeredi if (need_lookup) { 276272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2763d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27642675a4ebSAl Viro return PTR_ERR(dentry); 2765d18e9008SMiklos Szeredi 2766d18e9008SMiklos Szeredi if (create_error) { 2767d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2768d18e9008SMiklos Szeredi 27692675a4ebSAl Viro error = create_error; 2770d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2771d18e9008SMiklos Szeredi if (!dentry->d_inode) 2772d18e9008SMiklos Szeredi goto out; 2773d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2774d18e9008SMiklos Szeredi goto out; 2775d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2776d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2777d18e9008SMiklos Szeredi goto out; 2778d18e9008SMiklos Szeredi } 2779d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2780d18e9008SMiklos Szeredi } 2781d18e9008SMiklos Szeredi } 2782d18e9008SMiklos Szeredi looked_up: 2783d18e9008SMiklos Szeredi path->dentry = dentry; 2784d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 27852675a4ebSAl Viro return 1; 2786d18e9008SMiklos Szeredi } 2787d18e9008SMiklos Szeredi 278831e6b01fSNick Piggin /* 27891acf0af9SDavid Howells * Look up and maybe create and open the last component. 2790d58ffd35SMiklos Szeredi * 2791d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2792d58ffd35SMiklos Szeredi * 27931acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 27941acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 27951acf0af9SDavid Howells * 27961acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 27971acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 27981acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 27991acf0af9SDavid Howells * specified then a negative dentry may be returned. 28001acf0af9SDavid Howells * 28011acf0af9SDavid Howells * An error code is returned otherwise. 28021acf0af9SDavid Howells * 28031acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28041acf0af9SDavid Howells * cleared otherwise prior to returning. 2805d58ffd35SMiklos Szeredi */ 28062675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 280730d90494SAl Viro struct file *file, 2808d58ffd35SMiklos Szeredi const struct open_flags *op, 280964894cf8SAl Viro bool got_write, int *opened) 2810d58ffd35SMiklos Szeredi { 2811d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 281254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2813d58ffd35SMiklos Szeredi struct dentry *dentry; 2814d58ffd35SMiklos Szeredi int error; 281554ef4872SMiklos Szeredi bool need_lookup; 2816d58ffd35SMiklos Szeredi 281747237687SAl Viro *opened &= ~FILE_CREATED; 2818201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2819d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28202675a4ebSAl Viro return PTR_ERR(dentry); 2821d58ffd35SMiklos Szeredi 2822d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2823d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2824d18e9008SMiklos Szeredi goto out_no_open; 2825d18e9008SMiklos Szeredi 2826d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 282764894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 282847237687SAl Viro need_lookup, opened); 2829d18e9008SMiklos Szeredi } 2830d18e9008SMiklos Szeredi 283154ef4872SMiklos Szeredi if (need_lookup) { 283254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 283354ef4872SMiklos Szeredi 283472bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 283554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28362675a4ebSAl Viro return PTR_ERR(dentry); 283754ef4872SMiklos Szeredi } 283854ef4872SMiklos Szeredi 2839d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2840d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2841d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2842d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2843d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2844d58ffd35SMiklos Szeredi /* 2845d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2846d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2847d58ffd35SMiklos Szeredi * the time when the file is created and when 2848d58ffd35SMiklos Szeredi * a permanent write count is taken through 2849015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2850d58ffd35SMiklos Szeredi */ 285164894cf8SAl Viro if (!got_write) { 285264894cf8SAl Viro error = -EROFS; 2853d58ffd35SMiklos Szeredi goto out_dput; 285464894cf8SAl Viro } 285547237687SAl Viro *opened |= FILE_CREATED; 2856d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2857d58ffd35SMiklos Szeredi if (error) 2858d58ffd35SMiklos Szeredi goto out_dput; 2859312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2860312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2861d58ffd35SMiklos Szeredi if (error) 2862d58ffd35SMiklos Szeredi goto out_dput; 2863d58ffd35SMiklos Szeredi } 2864d18e9008SMiklos Szeredi out_no_open: 2865d58ffd35SMiklos Szeredi path->dentry = dentry; 2866d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 28672675a4ebSAl Viro return 1; 2868d58ffd35SMiklos Szeredi 2869d58ffd35SMiklos Szeredi out_dput: 2870d58ffd35SMiklos Szeredi dput(dentry); 28712675a4ebSAl Viro return error; 2872d58ffd35SMiklos Szeredi } 2873d58ffd35SMiklos Szeredi 2874d58ffd35SMiklos Szeredi /* 2875fe2d35ffSAl Viro * Handle the last step of open() 287631e6b01fSNick Piggin */ 28772675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 287830d90494SAl Viro struct file *file, const struct open_flags *op, 2879669abf4eSJeff Layton int *opened, struct filename *name) 2880fb1cc555SAl Viro { 2881a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2882ca344a89SAl Viro int open_flag = op->open_flag; 288377d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 288464894cf8SAl Viro bool got_write = false; 2885bcda7652SAl Viro int acc_mode = op->acc_mode; 2886a1eb3315SMiklos Szeredi struct inode *inode; 288777d660a8SMiklos Szeredi bool symlink_ok = false; 288816b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 288916b1c1cdSMiklos Szeredi bool retried = false; 289016c2cd71SAl Viro int error; 2891fb1cc555SAl Viro 2892c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2893c3e380b0SAl Viro nd->flags |= op->intent; 2894c3e380b0SAl Viro 2895bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2896fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2897fe2d35ffSAl Viro if (error) 28982675a4ebSAl Viro return error; 2899e83db167SMiklos Szeredi goto finish_open; 29001f36f774SAl Viro } 2901a2c36b45SAl Viro 2902ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2903fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2904fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2905bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 290677d660a8SMiklos Szeredi symlink_ok = true; 2907fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2908e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 290971574865SMiklos Szeredi if (likely(!error)) 291071574865SMiklos Szeredi goto finish_lookup; 291171574865SMiklos Szeredi 2912ce57dfc1SAl Viro if (error < 0) 29132675a4ebSAl Viro goto out; 2914a1eb3315SMiklos Szeredi 291537d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2916b6183df7SMiklos Szeredi } else { 2917fe2d35ffSAl Viro /* create side of things */ 2918a3fbbde7SAl Viro /* 2919b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2920b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2921b6183df7SMiklos Szeredi * about to look up 2922a3fbbde7SAl Viro */ 29239f1fafeeSAl Viro error = complete_walk(nd); 29249f1fafeeSAl Viro if (error) 29252675a4ebSAl Viro return error; 2926fe2d35ffSAl Viro 292733e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 292816c2cd71SAl Viro error = -EISDIR; 29291f36f774SAl Viro /* trailing slashes? */ 293031e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29312675a4ebSAl Viro goto out; 2932b6183df7SMiklos Szeredi } 29331f36f774SAl Viro 293416b1c1cdSMiklos Szeredi retry_lookup: 293564894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 293664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 293764894cf8SAl Viro if (!error) 293864894cf8SAl Viro got_write = true; 293964894cf8SAl Viro /* 294064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 294164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 294264894cf8SAl Viro * dropping this one anyway. 294364894cf8SAl Viro */ 294464894cf8SAl Viro } 2945a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 294664894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2947fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2948fb1cc555SAl Viro 29492675a4ebSAl Viro if (error <= 0) { 29502675a4ebSAl Viro if (error) 2951d58ffd35SMiklos Szeredi goto out; 29526c0d46c4SAl Viro 295347237687SAl Viro if ((*opened & FILE_CREATED) || 2954496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 295577d660a8SMiklos Szeredi will_truncate = false; 2956d18e9008SMiklos Szeredi 2957adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2958d18e9008SMiklos Szeredi goto opened; 2959d18e9008SMiklos Szeredi } 2960d18e9008SMiklos Szeredi 296147237687SAl Viro if (*opened & FILE_CREATED) { 29629b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2963ca344a89SAl Viro open_flag &= ~O_TRUNC; 296477d660a8SMiklos Szeredi will_truncate = false; 2965bcda7652SAl Viro acc_mode = MAY_OPEN; 2966d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2967e83db167SMiklos Szeredi goto finish_open_created; 2968fb1cc555SAl Viro } 2969fb1cc555SAl Viro 2970fb1cc555SAl Viro /* 29713134f37eSJeff Layton * create/update audit record if it already exists. 2972fb1cc555SAl Viro */ 29733134f37eSJeff Layton if (path->dentry->d_inode) 2974adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 2975fb1cc555SAl Viro 2976d18e9008SMiklos Szeredi /* 2977d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2978d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2979d18e9008SMiklos Szeredi * necessary...) 2980d18e9008SMiklos Szeredi */ 298164894cf8SAl Viro if (got_write) { 2982d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 298364894cf8SAl Viro got_write = false; 2984d18e9008SMiklos Szeredi } 2985d18e9008SMiklos Szeredi 2986fb1cc555SAl Viro error = -EEXIST; 2987f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 2988fb1cc555SAl Viro goto exit_dput; 2989fb1cc555SAl Viro 29909875cf80SDavid Howells error = follow_managed(path, nd->flags); 29919875cf80SDavid Howells if (error < 0) 2992fb1cc555SAl Viro goto exit_dput; 2993fb1cc555SAl Viro 2994a3fbbde7SAl Viro if (error) 2995a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 2996a3fbbde7SAl Viro 2997decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 2998decf3400SMiklos Szeredi inode = path->dentry->d_inode; 29995f5daac1SMiklos Szeredi finish_lookup: 30005f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 3001fb1cc555SAl Viro error = -ENOENT; 300254c33e7fSMiklos Szeredi if (!inode) { 300354c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 30042675a4ebSAl Viro goto out; 300554c33e7fSMiklos Szeredi } 30069e67f361SAl Viro 3007d45ea867SMiklos Szeredi if (should_follow_link(inode, !symlink_ok)) { 3008d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3009d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 3010d45ea867SMiklos Szeredi error = -ECHILD; 30112675a4ebSAl Viro goto out; 3012d45ea867SMiklos Szeredi } 3013d45ea867SMiklos Szeredi } 3014d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 30152675a4ebSAl Viro return 1; 3016d45ea867SMiklos Szeredi } 3017fb1cc555SAl Viro 301816b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 3019fb1cc555SAl Viro path_to_nameidata(path, nd); 302016b1c1cdSMiklos Szeredi } else { 302116b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 302216b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 302316b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 302416b1c1cdSMiklos Szeredi 302516b1c1cdSMiklos Szeredi } 3026decf3400SMiklos Szeredi nd->inode = inode; 3027a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3028bc77daa7SAl Viro finish_open: 3029a3fbbde7SAl Viro error = complete_walk(nd); 303016b1c1cdSMiklos Szeredi if (error) { 303116b1c1cdSMiklos Szeredi path_put(&save_parent); 30322675a4ebSAl Viro return error; 303316b1c1cdSMiklos Szeredi } 3034bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3035fb1cc555SAl Viro error = -EISDIR; 3036050ac841SMiklos Szeredi if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) 30372675a4ebSAl Viro goto out; 3038af2f5542SMiklos Szeredi error = -ENOTDIR; 303905252901SAl Viro if ((nd->flags & LOOKUP_DIRECTORY) && !can_lookup(nd->inode)) 30402675a4ebSAl Viro goto out; 30416c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 304277d660a8SMiklos Szeredi will_truncate = false; 30436c0d46c4SAl Viro 30440f9d1a10SAl Viro if (will_truncate) { 30450f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30460f9d1a10SAl Viro if (error) 30472675a4ebSAl Viro goto out; 304864894cf8SAl Viro got_write = true; 30490f9d1a10SAl Viro } 3050e83db167SMiklos Szeredi finish_open_created: 3051bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3052ca344a89SAl Viro if (error) 30532675a4ebSAl Viro goto out; 305430d90494SAl Viro file->f_path.mnt = nd->path.mnt; 305530d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 305630d90494SAl Viro if (error) { 305730d90494SAl Viro if (error == -EOPENSTALE) 3058f60dc3dbSMiklos Szeredi goto stale_open; 3059015c3bbcSMiklos Szeredi goto out; 3060f60dc3dbSMiklos Szeredi } 3061a8277b9bSMiklos Szeredi opened: 30622675a4ebSAl Viro error = open_check_o_direct(file); 3063015c3bbcSMiklos Szeredi if (error) 3064015c3bbcSMiklos Szeredi goto exit_fput; 30652675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 3066aa4caadbSMiklos Szeredi if (error) 3067aa4caadbSMiklos Szeredi goto exit_fput; 3068aa4caadbSMiklos Szeredi 30690f9d1a10SAl Viro if (will_truncate) { 30702675a4ebSAl Viro error = handle_truncate(file); 3071aa4caadbSMiklos Szeredi if (error) 3072aa4caadbSMiklos Szeredi goto exit_fput; 30730f9d1a10SAl Viro } 3074ca344a89SAl Viro out: 307564894cf8SAl Viro if (got_write) 30760f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 307716b1c1cdSMiklos Szeredi path_put(&save_parent); 3078e276ae67SMiklos Szeredi terminate_walk(nd); 30792675a4ebSAl Viro return error; 3080fb1cc555SAl Viro 3081fb1cc555SAl Viro exit_dput: 3082fb1cc555SAl Viro path_put_conditional(path, nd); 3083ca344a89SAl Viro goto out; 3084015c3bbcSMiklos Szeredi exit_fput: 30852675a4ebSAl Viro fput(file); 30862675a4ebSAl Viro goto out; 3087015c3bbcSMiklos Szeredi 3088f60dc3dbSMiklos Szeredi stale_open: 3089f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3090f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3091f60dc3dbSMiklos Szeredi goto out; 3092f60dc3dbSMiklos Szeredi 3093f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3094f60dc3dbSMiklos Szeredi path_put(&nd->path); 3095f60dc3dbSMiklos Szeredi nd->path = save_parent; 3096f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3097f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3098f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 309964894cf8SAl Viro if (got_write) { 3100f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 310164894cf8SAl Viro got_write = false; 3102f60dc3dbSMiklos Szeredi } 3103f60dc3dbSMiklos Szeredi retried = true; 3104f60dc3dbSMiklos Szeredi goto retry_lookup; 3105fb1cc555SAl Viro } 3106fb1cc555SAl Viro 310760545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 310860545d0dSAl Viro struct nameidata *nd, int flags, 310960545d0dSAl Viro const struct open_flags *op, 311060545d0dSAl Viro struct file *file, int *opened) 311160545d0dSAl Viro { 311260545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 311360545d0dSAl Viro struct dentry *dentry, *child; 311460545d0dSAl Viro struct inode *dir; 311560545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 311660545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 311760545d0dSAl Viro if (unlikely(error)) 311860545d0dSAl Viro return error; 311960545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 312060545d0dSAl Viro if (unlikely(error)) 312160545d0dSAl Viro goto out; 312260545d0dSAl Viro /* we want directory to be writable */ 312360545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 312460545d0dSAl Viro if (error) 312560545d0dSAl Viro goto out2; 312660545d0dSAl Viro dentry = nd->path.dentry; 312760545d0dSAl Viro dir = dentry->d_inode; 312860545d0dSAl Viro if (!dir->i_op->tmpfile) { 312960545d0dSAl Viro error = -EOPNOTSUPP; 313060545d0dSAl Viro goto out2; 313160545d0dSAl Viro } 313260545d0dSAl Viro child = d_alloc(dentry, &name); 313360545d0dSAl Viro if (unlikely(!child)) { 313460545d0dSAl Viro error = -ENOMEM; 313560545d0dSAl Viro goto out2; 313660545d0dSAl Viro } 313760545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 313860545d0dSAl Viro nd->flags |= op->intent; 313960545d0dSAl Viro dput(nd->path.dentry); 314060545d0dSAl Viro nd->path.dentry = child; 314160545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 314260545d0dSAl Viro if (error) 314360545d0dSAl Viro goto out2; 314460545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 314560545d0dSAl Viro error = may_open(&nd->path, op->acc_mode, op->open_flag); 314660545d0dSAl Viro if (error) 314760545d0dSAl Viro goto out2; 314860545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 314960545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 315060545d0dSAl Viro if (error) 315160545d0dSAl Viro goto out2; 315260545d0dSAl Viro error = open_check_o_direct(file); 3153f4e0c30cSAl Viro if (error) { 315460545d0dSAl Viro fput(file); 3155f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3156f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3157f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3158f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3159f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3160f4e0c30cSAl Viro } 316160545d0dSAl Viro out2: 316260545d0dSAl Viro mnt_drop_write(nd->path.mnt); 316360545d0dSAl Viro out: 316460545d0dSAl Viro path_put(&nd->path); 316560545d0dSAl Viro return error; 316660545d0dSAl Viro } 316760545d0dSAl Viro 3168669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 316973d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 31701da177e4SLinus Torvalds { 3171fe2d35ffSAl Viro struct file *base = NULL; 317230d90494SAl Viro struct file *file; 31739850c056SAl Viro struct path path; 317447237687SAl Viro int opened = 0; 317513aab428SAl Viro int error; 317631e6b01fSNick Piggin 317730d90494SAl Viro file = get_empty_filp(); 31781afc99beSAl Viro if (IS_ERR(file)) 31791afc99beSAl Viro return file; 318031e6b01fSNick Piggin 318130d90494SAl Viro file->f_flags = op->open_flag; 318231e6b01fSNick Piggin 3183bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 318460545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 318560545d0dSAl Viro goto out; 318660545d0dSAl Viro } 318760545d0dSAl Viro 3188669abf4eSJeff Layton error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); 318931e6b01fSNick Piggin if (unlikely(error)) 31902675a4ebSAl Viro goto out; 319131e6b01fSNick Piggin 3192fe2d35ffSAl Viro current->total_link_count = 0; 3193669abf4eSJeff Layton error = link_path_walk(pathname->name, nd); 319431e6b01fSNick Piggin if (unlikely(error)) 31952675a4ebSAl Viro goto out; 31961da177e4SLinus Torvalds 31972675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 31982675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 31997b9337aaSNick Piggin struct path link = path; 3200def4af30SAl Viro void *cookie; 3201574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 320273d049a4SAl Viro path_put_conditional(&path, nd); 320373d049a4SAl Viro path_put(&nd->path); 32042675a4ebSAl Viro error = -ELOOP; 320540b39136SAl Viro break; 320640b39136SAl Viro } 3207800179c9SKees Cook error = may_follow_link(&link, nd); 3208800179c9SKees Cook if (unlikely(error)) 3209800179c9SKees Cook break; 321073d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 321173d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3212574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3213c3e380b0SAl Viro if (unlikely(error)) 32142675a4ebSAl Viro break; 32152675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3216574197e0SAl Viro put_link(nd, &link, cookie); 3217806b681cSAl Viro } 321810fa8e62SAl Viro out: 321973d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 322073d049a4SAl Viro path_put(&nd->root); 3221fe2d35ffSAl Viro if (base) 3222fe2d35ffSAl Viro fput(base); 32232675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32242675a4ebSAl Viro BUG_ON(!error); 322530d90494SAl Viro put_filp(file); 3226015c3bbcSMiklos Szeredi } 32272675a4ebSAl Viro if (unlikely(error)) { 32282675a4ebSAl Viro if (error == -EOPENSTALE) { 32292675a4ebSAl Viro if (flags & LOOKUP_RCU) 32302675a4ebSAl Viro error = -ECHILD; 32312675a4ebSAl Viro else 32322675a4ebSAl Viro error = -ESTALE; 32332675a4ebSAl Viro } 32342675a4ebSAl Viro file = ERR_PTR(error); 32352675a4ebSAl Viro } 32362675a4ebSAl Viro return file; 3237de459215SKirill Korotaev } 32381da177e4SLinus Torvalds 3239669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3240f9652e10SAl Viro const struct open_flags *op) 324113aab428SAl Viro { 324273d049a4SAl Viro struct nameidata nd; 3243f9652e10SAl Viro int flags = op->lookup_flags; 324413aab428SAl Viro struct file *filp; 324513aab428SAl Viro 324673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 324713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 324873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 324913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 325073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 325113aab428SAl Viro return filp; 325213aab428SAl Viro } 325313aab428SAl Viro 325473d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3255f9652e10SAl Viro const char *name, const struct open_flags *op) 325673d049a4SAl Viro { 325773d049a4SAl Viro struct nameidata nd; 325873d049a4SAl Viro struct file *file; 3259669abf4eSJeff Layton struct filename filename = { .name = name }; 3260f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 326173d049a4SAl Viro 326273d049a4SAl Viro nd.root.mnt = mnt; 326373d049a4SAl Viro nd.root.dentry = dentry; 326473d049a4SAl Viro 3265bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 326673d049a4SAl Viro return ERR_PTR(-ELOOP); 326773d049a4SAl Viro 3268669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); 326973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3270669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags); 327173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3272669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); 327373d049a4SAl Viro return file; 327473d049a4SAl Viro } 327573d049a4SAl Viro 32761ac12b4bSJeff Layton struct dentry *kern_path_create(int dfd, const char *pathname, 32771ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 32781da177e4SLinus Torvalds { 3279c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3280ed75e95dSAl Viro struct nameidata nd; 3281c30dabfeSJan Kara int err2; 32821ac12b4bSJeff Layton int error; 32831ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 32841ac12b4bSJeff Layton 32851ac12b4bSJeff Layton /* 32861ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 32871ac12b4bSJeff Layton * other flags passed in are ignored! 32881ac12b4bSJeff Layton */ 32891ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 32901ac12b4bSJeff Layton 32911ac12b4bSJeff Layton error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); 3292ed75e95dSAl Viro if (error) 3293ed75e95dSAl Viro return ERR_PTR(error); 32941da177e4SLinus Torvalds 3295c663e5d8SChristoph Hellwig /* 3296c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3297c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3298c663e5d8SChristoph Hellwig */ 3299ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3300ed75e95dSAl Viro goto out; 3301ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3302ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3303c663e5d8SChristoph Hellwig 3304c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3305c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3306c663e5d8SChristoph Hellwig /* 3307c663e5d8SChristoph Hellwig * Do the final lookup. 3308c663e5d8SChristoph Hellwig */ 3309ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3310ed75e95dSAl Viro dentry = lookup_hash(&nd); 33111da177e4SLinus Torvalds if (IS_ERR(dentry)) 3312a8104a9fSAl Viro goto unlock; 3313c663e5d8SChristoph Hellwig 3314a8104a9fSAl Viro error = -EEXIST; 3315e9baf6e5SAl Viro if (dentry->d_inode) 3316a8104a9fSAl Viro goto fail; 3317c663e5d8SChristoph Hellwig /* 3318c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3319c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3320c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3321c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3322c663e5d8SChristoph Hellwig */ 3323ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3324a8104a9fSAl Viro error = -ENOENT; 3325ed75e95dSAl Viro goto fail; 3326e9baf6e5SAl Viro } 3327c30dabfeSJan Kara if (unlikely(err2)) { 3328c30dabfeSJan Kara error = err2; 3329a8104a9fSAl Viro goto fail; 3330c30dabfeSJan Kara } 3331ed75e95dSAl Viro *path = nd.path; 3332e9baf6e5SAl Viro return dentry; 33331da177e4SLinus Torvalds fail: 3334a8104a9fSAl Viro dput(dentry); 3335a8104a9fSAl Viro dentry = ERR_PTR(error); 3336a8104a9fSAl Viro unlock: 3337dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3338c30dabfeSJan Kara if (!err2) 3339c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3340ed75e95dSAl Viro out: 3341dae6ad8fSAl Viro path_put(&nd.path); 3342ed75e95dSAl Viro return dentry; 3343dae6ad8fSAl Viro } 3344dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3345dae6ad8fSAl Viro 3346921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3347921a1650SAl Viro { 3348921a1650SAl Viro dput(dentry); 3349921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3350a8104a9fSAl Viro mnt_drop_write(path->mnt); 3351921a1650SAl Viro path_put(path); 3352921a1650SAl Viro } 3353921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3354921a1650SAl Viro 33551ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33561ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3357dae6ad8fSAl Viro { 335891a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3359dae6ad8fSAl Viro struct dentry *res; 3360dae6ad8fSAl Viro if (IS_ERR(tmp)) 3361dae6ad8fSAl Viro return ERR_CAST(tmp); 33621ac12b4bSJeff Layton res = kern_path_create(dfd, tmp->name, path, lookup_flags); 3363dae6ad8fSAl Viro putname(tmp); 3364dae6ad8fSAl Viro return res; 3365dae6ad8fSAl Viro } 3366dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3367dae6ad8fSAl Viro 33681a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 33691da177e4SLinus Torvalds { 3370a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 33711da177e4SLinus Torvalds 33721da177e4SLinus Torvalds if (error) 33731da177e4SLinus Torvalds return error; 33741da177e4SLinus Torvalds 3375975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 33761da177e4SLinus Torvalds return -EPERM; 33771da177e4SLinus Torvalds 3378acfa4380SAl Viro if (!dir->i_op->mknod) 33791da177e4SLinus Torvalds return -EPERM; 33801da177e4SLinus Torvalds 338108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 338208ce5f16SSerge E. Hallyn if (error) 338308ce5f16SSerge E. Hallyn return error; 338408ce5f16SSerge E. Hallyn 33851da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 33861da177e4SLinus Torvalds if (error) 33871da177e4SLinus Torvalds return error; 33881da177e4SLinus Torvalds 33891da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3390a74574aaSStephen Smalley if (!error) 3391f38aa942SAmy Griffis fsnotify_create(dir, dentry); 33921da177e4SLinus Torvalds return error; 33931da177e4SLinus Torvalds } 33941da177e4SLinus Torvalds 3395f69aac00SAl Viro static int may_mknod(umode_t mode) 3396463c3197SDave Hansen { 3397463c3197SDave Hansen switch (mode & S_IFMT) { 3398463c3197SDave Hansen case S_IFREG: 3399463c3197SDave Hansen case S_IFCHR: 3400463c3197SDave Hansen case S_IFBLK: 3401463c3197SDave Hansen case S_IFIFO: 3402463c3197SDave Hansen case S_IFSOCK: 3403463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3404463c3197SDave Hansen return 0; 3405463c3197SDave Hansen case S_IFDIR: 3406463c3197SDave Hansen return -EPERM; 3407463c3197SDave Hansen default: 3408463c3197SDave Hansen return -EINVAL; 3409463c3197SDave Hansen } 3410463c3197SDave Hansen } 3411463c3197SDave Hansen 34128208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34132e4d0924SHeiko Carstens unsigned, dev) 34141da177e4SLinus Torvalds { 34151da177e4SLinus Torvalds struct dentry *dentry; 3416dae6ad8fSAl Viro struct path path; 3417dae6ad8fSAl Viro int error; 3418972567f1SJeff Layton unsigned int lookup_flags = 0; 34191da177e4SLinus Torvalds 34208e4bfca1SAl Viro error = may_mknod(mode); 34218e4bfca1SAl Viro if (error) 34228e4bfca1SAl Viro return error; 3423972567f1SJeff Layton retry: 3424972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3425dae6ad8fSAl Viro if (IS_ERR(dentry)) 3426dae6ad8fSAl Viro return PTR_ERR(dentry); 34272ad94ae6SAl Viro 3428dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3429ce3b0f8dSAl Viro mode &= ~current_umask(); 3430dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3431be6d3e56SKentaro Takeda if (error) 3432a8104a9fSAl Viro goto out; 34331da177e4SLinus Torvalds switch (mode & S_IFMT) { 34341da177e4SLinus Torvalds case 0: case S_IFREG: 3435312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34361da177e4SLinus Torvalds break; 34371da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3438dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34391da177e4SLinus Torvalds new_decode_dev(dev)); 34401da177e4SLinus Torvalds break; 34411da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3442dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34431da177e4SLinus Torvalds break; 34441da177e4SLinus Torvalds } 3445a8104a9fSAl Viro out: 3446921a1650SAl Viro done_path_create(&path, dentry); 3447972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3448972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3449972567f1SJeff Layton goto retry; 3450972567f1SJeff Layton } 34511da177e4SLinus Torvalds return error; 34521da177e4SLinus Torvalds } 34531da177e4SLinus Torvalds 34548208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34555590ff0dSUlrich Drepper { 34565590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34575590ff0dSUlrich Drepper } 34585590ff0dSUlrich Drepper 345918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 34601da177e4SLinus Torvalds { 3461a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34628de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34631da177e4SLinus Torvalds 34641da177e4SLinus Torvalds if (error) 34651da177e4SLinus Torvalds return error; 34661da177e4SLinus Torvalds 3467acfa4380SAl Viro if (!dir->i_op->mkdir) 34681da177e4SLinus Torvalds return -EPERM; 34691da177e4SLinus Torvalds 34701da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 34711da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 34721da177e4SLinus Torvalds if (error) 34731da177e4SLinus Torvalds return error; 34741da177e4SLinus Torvalds 34758de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 34768de52778SAl Viro return -EMLINK; 34778de52778SAl Viro 34781da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3479a74574aaSStephen Smalley if (!error) 3480f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 34811da177e4SLinus Torvalds return error; 34821da177e4SLinus Torvalds } 34831da177e4SLinus Torvalds 3484a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 34851da177e4SLinus Torvalds { 34866902d925SDave Hansen struct dentry *dentry; 3487dae6ad8fSAl Viro struct path path; 3488dae6ad8fSAl Viro int error; 3489b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 34901da177e4SLinus Torvalds 3491b76d8b82SJeff Layton retry: 3492b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 34936902d925SDave Hansen if (IS_ERR(dentry)) 3494dae6ad8fSAl Viro return PTR_ERR(dentry); 34956902d925SDave Hansen 3496dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3497ce3b0f8dSAl Viro mode &= ~current_umask(); 3498dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3499a8104a9fSAl Viro if (!error) 3500dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3501921a1650SAl Viro done_path_create(&path, dentry); 3502b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3503b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3504b76d8b82SJeff Layton goto retry; 3505b76d8b82SJeff Layton } 35061da177e4SLinus Torvalds return error; 35071da177e4SLinus Torvalds } 35081da177e4SLinus Torvalds 3509a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35105590ff0dSUlrich Drepper { 35115590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35125590ff0dSUlrich Drepper } 35135590ff0dSUlrich Drepper 35141da177e4SLinus Torvalds /* 3515a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3516c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3517a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3518a71905f0SSage Weil * then we drop the dentry now. 35191da177e4SLinus Torvalds * 35201da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35211da177e4SLinus Torvalds * do a 35221da177e4SLinus Torvalds * 35231da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35241da177e4SLinus Torvalds * return -EBUSY; 35251da177e4SLinus Torvalds * 35261da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35271da177e4SLinus Torvalds * that is still in use by something else.. 35281da177e4SLinus Torvalds */ 35291da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35301da177e4SLinus Torvalds { 35311da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35321da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 353398474236SWaiman Long if (dentry->d_lockref.count == 1) 35341da177e4SLinus Torvalds __d_drop(dentry); 35351da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35361da177e4SLinus Torvalds } 35371da177e4SLinus Torvalds 35381da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35391da177e4SLinus Torvalds { 35401da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35411da177e4SLinus Torvalds 35421da177e4SLinus Torvalds if (error) 35431da177e4SLinus Torvalds return error; 35441da177e4SLinus Torvalds 3545acfa4380SAl Viro if (!dir->i_op->rmdir) 35461da177e4SLinus Torvalds return -EPERM; 35471da177e4SLinus Torvalds 35481d2ef590SAl Viro dget(dentry); 35491b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3550912dbc15SSage Weil 35511da177e4SLinus Torvalds error = -EBUSY; 3552912dbc15SSage Weil if (d_mountpoint(dentry)) 3553912dbc15SSage Weil goto out; 3554912dbc15SSage Weil 35551da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3556912dbc15SSage Weil if (error) 3557912dbc15SSage Weil goto out; 3558912dbc15SSage Weil 35593cebde24SSage Weil shrink_dcache_parent(dentry); 35601da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3561912dbc15SSage Weil if (error) 3562912dbc15SSage Weil goto out; 3563912dbc15SSage Weil 35641da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3565d83c49f3SAl Viro dont_mount(dentry); 35661da177e4SLinus Torvalds 3567912dbc15SSage Weil out: 3568912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 35691d2ef590SAl Viro dput(dentry); 3570912dbc15SSage Weil if (!error) 3571912dbc15SSage Weil d_delete(dentry); 35721da177e4SLinus Torvalds return error; 35731da177e4SLinus Torvalds } 35741da177e4SLinus Torvalds 35755590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 35761da177e4SLinus Torvalds { 35771da177e4SLinus Torvalds int error = 0; 357891a27b2aSJeff Layton struct filename *name; 35791da177e4SLinus Torvalds struct dentry *dentry; 35801da177e4SLinus Torvalds struct nameidata nd; 3581c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3582c6ee9206SJeff Layton retry: 3583c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 358491a27b2aSJeff Layton if (IS_ERR(name)) 358591a27b2aSJeff Layton return PTR_ERR(name); 35861da177e4SLinus Torvalds 35871da177e4SLinus Torvalds switch(nd.last_type) { 35881da177e4SLinus Torvalds case LAST_DOTDOT: 35891da177e4SLinus Torvalds error = -ENOTEMPTY; 35901da177e4SLinus Torvalds goto exit1; 35911da177e4SLinus Torvalds case LAST_DOT: 35921da177e4SLinus Torvalds error = -EINVAL; 35931da177e4SLinus Torvalds goto exit1; 35941da177e4SLinus Torvalds case LAST_ROOT: 35951da177e4SLinus Torvalds error = -EBUSY; 35961da177e4SLinus Torvalds goto exit1; 35971da177e4SLinus Torvalds } 35980612d9fbSOGAWA Hirofumi 35990612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3600c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3601c30dabfeSJan Kara if (error) 3602c30dabfeSJan Kara goto exit1; 36030612d9fbSOGAWA Hirofumi 36044ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 360549705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36061da177e4SLinus Torvalds error = PTR_ERR(dentry); 36076902d925SDave Hansen if (IS_ERR(dentry)) 36086902d925SDave Hansen goto exit2; 3609e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3610e6bc45d6STheodore Ts'o error = -ENOENT; 3611e6bc45d6STheodore Ts'o goto exit3; 3612e6bc45d6STheodore Ts'o } 3613be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3614be6d3e56SKentaro Takeda if (error) 3615c30dabfeSJan Kara goto exit3; 36164ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 36170622753bSDave Hansen exit3: 36181da177e4SLinus Torvalds dput(dentry); 36196902d925SDave Hansen exit2: 36204ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3621c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 36221da177e4SLinus Torvalds exit1: 36231d957f9bSJan Blunck path_put(&nd.path); 36241da177e4SLinus Torvalds putname(name); 3625c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3626c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3627c6ee9206SJeff Layton goto retry; 3628c6ee9206SJeff Layton } 36291da177e4SLinus Torvalds return error; 36301da177e4SLinus Torvalds } 36311da177e4SLinus Torvalds 36323cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36335590ff0dSUlrich Drepper { 36345590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36355590ff0dSUlrich Drepper } 36365590ff0dSUlrich Drepper 36371da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 36381da177e4SLinus Torvalds { 36391da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 36401da177e4SLinus Torvalds 36411da177e4SLinus Torvalds if (error) 36421da177e4SLinus Torvalds return error; 36431da177e4SLinus Torvalds 3644acfa4380SAl Viro if (!dir->i_op->unlink) 36451da177e4SLinus Torvalds return -EPERM; 36461da177e4SLinus Torvalds 36471b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 36481da177e4SLinus Torvalds if (d_mountpoint(dentry)) 36491da177e4SLinus Torvalds error = -EBUSY; 36501da177e4SLinus Torvalds else { 36511da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3652bec1052eSAl Viro if (!error) { 36531da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3654bec1052eSAl Viro if (!error) 3655d83c49f3SAl Viro dont_mount(dentry); 3656bec1052eSAl Viro } 36571da177e4SLinus Torvalds } 36581b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 36591da177e4SLinus Torvalds 36601da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 36611da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 3662ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 36631da177e4SLinus Torvalds d_delete(dentry); 36641da177e4SLinus Torvalds } 36650eeca283SRobert Love 36661da177e4SLinus Torvalds return error; 36671da177e4SLinus Torvalds } 36681da177e4SLinus Torvalds 36691da177e4SLinus Torvalds /* 36701da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 36711b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 36721da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 36731da177e4SLinus Torvalds * while waiting on the I/O. 36741da177e4SLinus Torvalds */ 36755590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 36761da177e4SLinus Torvalds { 36772ad94ae6SAl Viro int error; 367891a27b2aSJeff Layton struct filename *name; 36791da177e4SLinus Torvalds struct dentry *dentry; 36801da177e4SLinus Torvalds struct nameidata nd; 36811da177e4SLinus Torvalds struct inode *inode = NULL; 36825d18f813SJeff Layton unsigned int lookup_flags = 0; 36835d18f813SJeff Layton retry: 36845d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 368591a27b2aSJeff Layton if (IS_ERR(name)) 368691a27b2aSJeff Layton return PTR_ERR(name); 36872ad94ae6SAl Viro 36881da177e4SLinus Torvalds error = -EISDIR; 36891da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 36901da177e4SLinus Torvalds goto exit1; 36910612d9fbSOGAWA Hirofumi 36920612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3693c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3694c30dabfeSJan Kara if (error) 3695c30dabfeSJan Kara goto exit1; 36960612d9fbSOGAWA Hirofumi 36974ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 369849705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36991da177e4SLinus Torvalds error = PTR_ERR(dentry); 37001da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37011da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 370250338b88STörök Edwin if (nd.last.name[nd.last.len]) 370350338b88STörök Edwin goto slashes; 37041da177e4SLinus Torvalds inode = dentry->d_inode; 370550338b88STörök Edwin if (!inode) 3706e6bc45d6STheodore Ts'o goto slashes; 37077de9c6eeSAl Viro ihold(inode); 3708be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3709be6d3e56SKentaro Takeda if (error) 3710c30dabfeSJan Kara goto exit2; 37114ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 37121da177e4SLinus Torvalds exit2: 37131da177e4SLinus Torvalds dput(dentry); 37141da177e4SLinus Torvalds } 37154ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 37161da177e4SLinus Torvalds if (inode) 37171da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3718c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 37191da177e4SLinus Torvalds exit1: 37201d957f9bSJan Blunck path_put(&nd.path); 37211da177e4SLinus Torvalds putname(name); 37225d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 37235d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 37245d18f813SJeff Layton inode = NULL; 37255d18f813SJeff Layton goto retry; 37265d18f813SJeff Layton } 37271da177e4SLinus Torvalds return error; 37281da177e4SLinus Torvalds 37291da177e4SLinus Torvalds slashes: 37301da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 37311da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 37321da177e4SLinus Torvalds goto exit2; 37331da177e4SLinus Torvalds } 37341da177e4SLinus Torvalds 37352e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 37365590ff0dSUlrich Drepper { 37375590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 37385590ff0dSUlrich Drepper return -EINVAL; 37395590ff0dSUlrich Drepper 37405590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 37415590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 37425590ff0dSUlrich Drepper 37435590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 37445590ff0dSUlrich Drepper } 37455590ff0dSUlrich Drepper 37463480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 37475590ff0dSUlrich Drepper { 37485590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 37495590ff0dSUlrich Drepper } 37505590ff0dSUlrich Drepper 3751db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 37521da177e4SLinus Torvalds { 3753a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37541da177e4SLinus Torvalds 37551da177e4SLinus Torvalds if (error) 37561da177e4SLinus Torvalds return error; 37571da177e4SLinus Torvalds 3758acfa4380SAl Viro if (!dir->i_op->symlink) 37591da177e4SLinus Torvalds return -EPERM; 37601da177e4SLinus Torvalds 37611da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 37621da177e4SLinus Torvalds if (error) 37631da177e4SLinus Torvalds return error; 37641da177e4SLinus Torvalds 37651da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3766a74574aaSStephen Smalley if (!error) 3767f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37681da177e4SLinus Torvalds return error; 37691da177e4SLinus Torvalds } 37701da177e4SLinus Torvalds 37712e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 37722e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 37731da177e4SLinus Torvalds { 37742ad94ae6SAl Viro int error; 377591a27b2aSJeff Layton struct filename *from; 37766902d925SDave Hansen struct dentry *dentry; 3777dae6ad8fSAl Viro struct path path; 3778f46d3567SJeff Layton unsigned int lookup_flags = 0; 37791da177e4SLinus Torvalds 37801da177e4SLinus Torvalds from = getname(oldname); 37811da177e4SLinus Torvalds if (IS_ERR(from)) 37821da177e4SLinus Torvalds return PTR_ERR(from); 3783f46d3567SJeff Layton retry: 3784f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 37851da177e4SLinus Torvalds error = PTR_ERR(dentry); 37866902d925SDave Hansen if (IS_ERR(dentry)) 3787dae6ad8fSAl Viro goto out_putname; 37886902d925SDave Hansen 378991a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3790a8104a9fSAl Viro if (!error) 379191a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3792921a1650SAl Viro done_path_create(&path, dentry); 3793f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3794f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3795f46d3567SJeff Layton goto retry; 3796f46d3567SJeff Layton } 37976902d925SDave Hansen out_putname: 37981da177e4SLinus Torvalds putname(from); 37991da177e4SLinus Torvalds return error; 38001da177e4SLinus Torvalds } 38011da177e4SLinus Torvalds 38023480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 38035590ff0dSUlrich Drepper { 38045590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 38055590ff0dSUlrich Drepper } 38065590ff0dSUlrich Drepper 38071da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 38081da177e4SLinus Torvalds { 38091da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 38108de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 38111da177e4SLinus Torvalds int error; 38121da177e4SLinus Torvalds 38131da177e4SLinus Torvalds if (!inode) 38141da177e4SLinus Torvalds return -ENOENT; 38151da177e4SLinus Torvalds 3816a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 38171da177e4SLinus Torvalds if (error) 38181da177e4SLinus Torvalds return error; 38191da177e4SLinus Torvalds 38201da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 38211da177e4SLinus Torvalds return -EXDEV; 38221da177e4SLinus Torvalds 38231da177e4SLinus Torvalds /* 38241da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 38251da177e4SLinus Torvalds */ 38261da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 38271da177e4SLinus Torvalds return -EPERM; 3828acfa4380SAl Viro if (!dir->i_op->link) 38291da177e4SLinus Torvalds return -EPERM; 38307e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 38311da177e4SLinus Torvalds return -EPERM; 38321da177e4SLinus Torvalds 38331da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 38341da177e4SLinus Torvalds if (error) 38351da177e4SLinus Torvalds return error; 38361da177e4SLinus Torvalds 38377e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3838aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3839f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3840aae8a97dSAneesh Kumar K.V error = -ENOENT; 38418de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 38428de52778SAl Viro error = -EMLINK; 3843aae8a97dSAneesh Kumar K.V else 38441da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3845f4e0c30cSAl Viro 3846f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3847f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3848f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3849f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3850f4e0c30cSAl Viro } 38517e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3852e31e14ecSStephen Smalley if (!error) 38537e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds } 38561da177e4SLinus Torvalds 38571da177e4SLinus Torvalds /* 38581da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 38591da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 38601da177e4SLinus Torvalds * newname. --KAB 38611da177e4SLinus Torvalds * 38621da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 38631da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 38641da177e4SLinus Torvalds * and other special files. --ADM 38651da177e4SLinus Torvalds */ 38662e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 38672e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 38681da177e4SLinus Torvalds { 38691da177e4SLinus Torvalds struct dentry *new_dentry; 3870dae6ad8fSAl Viro struct path old_path, new_path; 387111a7b371SAneesh Kumar K.V int how = 0; 38721da177e4SLinus Torvalds int error; 38731da177e4SLinus Torvalds 387411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3875c04030e1SUlrich Drepper return -EINVAL; 387611a7b371SAneesh Kumar K.V /* 3877f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3878f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3879f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 388011a7b371SAneesh Kumar K.V */ 3881f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3882f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3883f0cc6ffbSLinus Torvalds return -ENOENT; 388411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3885f0cc6ffbSLinus Torvalds } 3886c04030e1SUlrich Drepper 388711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 388811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 3889442e31caSJeff Layton retry: 389011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 38911da177e4SLinus Torvalds if (error) 38922ad94ae6SAl Viro return error; 38932ad94ae6SAl Viro 3894442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 3895442e31caSJeff Layton (how & LOOKUP_REVAL)); 38961da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 38976902d925SDave Hansen if (IS_ERR(new_dentry)) 3898dae6ad8fSAl Viro goto out; 3899dae6ad8fSAl Viro 3900dae6ad8fSAl Viro error = -EXDEV; 3901dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3902dae6ad8fSAl Viro goto out_dput; 3903800179c9SKees Cook error = may_linkat(&old_path); 3904800179c9SKees Cook if (unlikely(error)) 3905800179c9SKees Cook goto out_dput; 3906dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3907be6d3e56SKentaro Takeda if (error) 3908a8104a9fSAl Viro goto out_dput; 3909dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 391075c3f29dSDave Hansen out_dput: 3911921a1650SAl Viro done_path_create(&new_path, new_dentry); 3912442e31caSJeff Layton if (retry_estale(error, how)) { 3913442e31caSJeff Layton how |= LOOKUP_REVAL; 3914442e31caSJeff Layton goto retry; 3915442e31caSJeff Layton } 39161da177e4SLinus Torvalds out: 39172d8f3038SAl Viro path_put(&old_path); 39181da177e4SLinus Torvalds 39191da177e4SLinus Torvalds return error; 39201da177e4SLinus Torvalds } 39211da177e4SLinus Torvalds 39223480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 39235590ff0dSUlrich Drepper { 3924c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 39255590ff0dSUlrich Drepper } 39265590ff0dSUlrich Drepper 39271da177e4SLinus Torvalds /* 39281da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 39291da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 39301da177e4SLinus Torvalds * Problems: 39311da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 39321da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 39331da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3934a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 39351da177e4SLinus Torvalds * story. 39361da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 39371b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 39381da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 39391da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3940a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 39411da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 39421da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 39431da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3944a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 39451da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 39461da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 39471da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3948e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 39491b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 39501da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3951c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 39521da177e4SLinus Torvalds * locking]. 39531da177e4SLinus Torvalds */ 395475c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 39551da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 39561da177e4SLinus Torvalds { 39571da177e4SLinus Torvalds int error = 0; 39589055cba7SSage Weil struct inode *target = new_dentry->d_inode; 39598de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 39601da177e4SLinus Torvalds 39611da177e4SLinus Torvalds /* 39621da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 39631da177e4SLinus Torvalds * we'll need to flip '..'. 39641da177e4SLinus Torvalds */ 39651da177e4SLinus Torvalds if (new_dir != old_dir) { 3966f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 39671da177e4SLinus Torvalds if (error) 39681da177e4SLinus Torvalds return error; 39691da177e4SLinus Torvalds } 39701da177e4SLinus Torvalds 39711da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 39721da177e4SLinus Torvalds if (error) 39731da177e4SLinus Torvalds return error; 39741da177e4SLinus Torvalds 39751d2ef590SAl Viro dget(new_dentry); 3976d83c49f3SAl Viro if (target) 39771b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 39789055cba7SSage Weil 39791da177e4SLinus Torvalds error = -EBUSY; 39809055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 39819055cba7SSage Weil goto out; 39829055cba7SSage Weil 39838de52778SAl Viro error = -EMLINK; 39848de52778SAl Viro if (max_links && !target && new_dir != old_dir && 39858de52778SAl Viro new_dir->i_nlink >= max_links) 39868de52778SAl Viro goto out; 39878de52778SAl Viro 39883cebde24SSage Weil if (target) 39893cebde24SSage Weil shrink_dcache_parent(new_dentry); 39901da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 39919055cba7SSage Weil if (error) 39929055cba7SSage Weil goto out; 39939055cba7SSage Weil 39941da177e4SLinus Torvalds if (target) { 39951da177e4SLinus Torvalds target->i_flags |= S_DEAD; 3996d83c49f3SAl Viro dont_mount(new_dentry); 3997d83c49f3SAl Viro } 39989055cba7SSage Weil out: 39999055cba7SSage Weil if (target) 40001b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 40011d2ef590SAl Viro dput(new_dentry); 4002e31e14ecSStephen Smalley if (!error) 4003349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 40041da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 40051da177e4SLinus Torvalds return error; 40061da177e4SLinus Torvalds } 40071da177e4SLinus Torvalds 400875c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 40091da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 40101da177e4SLinus Torvalds { 401151892bbbSSage Weil struct inode *target = new_dentry->d_inode; 40121da177e4SLinus Torvalds int error; 40131da177e4SLinus Torvalds 40141da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 40151da177e4SLinus Torvalds if (error) 40161da177e4SLinus Torvalds return error; 40171da177e4SLinus Torvalds 40181da177e4SLinus Torvalds dget(new_dentry); 40191da177e4SLinus Torvalds if (target) 40201b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 402151892bbbSSage Weil 40221da177e4SLinus Torvalds error = -EBUSY; 402351892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 402451892bbbSSage Weil goto out; 402551892bbbSSage Weil 40261da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 402751892bbbSSage Weil if (error) 402851892bbbSSage Weil goto out; 402951892bbbSSage Weil 4030bec1052eSAl Viro if (target) 4031d83c49f3SAl Viro dont_mount(new_dentry); 4032349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 40331da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 403451892bbbSSage Weil out: 40351da177e4SLinus Torvalds if (target) 40361b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 40371da177e4SLinus Torvalds dput(new_dentry); 40381da177e4SLinus Torvalds return error; 40391da177e4SLinus Torvalds } 40401da177e4SLinus Torvalds 40411da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40421da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 40431da177e4SLinus Torvalds { 40441da177e4SLinus Torvalds int error; 40451da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 404659b0df21SEric Paris const unsigned char *old_name; 40471da177e4SLinus Torvalds 40481da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 40491da177e4SLinus Torvalds return 0; 40501da177e4SLinus Torvalds 40511da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 40521da177e4SLinus Torvalds if (error) 40531da177e4SLinus Torvalds return error; 40541da177e4SLinus Torvalds 40551da177e4SLinus Torvalds if (!new_dentry->d_inode) 4056a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 40571da177e4SLinus Torvalds else 40581da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 40591da177e4SLinus Torvalds if (error) 40601da177e4SLinus Torvalds return error; 40611da177e4SLinus Torvalds 4062acfa4380SAl Viro if (!old_dir->i_op->rename) 40631da177e4SLinus Torvalds return -EPERM; 40641da177e4SLinus Torvalds 40650eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 40660eeca283SRobert Love 40671da177e4SLinus Torvalds if (is_dir) 40681da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 40691da177e4SLinus Torvalds else 40701da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 4071123df294SAl Viro if (!error) 4072123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 40735a190ae6SAl Viro new_dentry->d_inode, old_dentry); 40740eeca283SRobert Love fsnotify_oldname_free(old_name); 40750eeca283SRobert Love 40761da177e4SLinus Torvalds return error; 40771da177e4SLinus Torvalds } 40781da177e4SLinus Torvalds 40792e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 40802e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40811da177e4SLinus Torvalds { 40821da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 40831da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 40841da177e4SLinus Torvalds struct dentry *trap; 40851da177e4SLinus Torvalds struct nameidata oldnd, newnd; 408691a27b2aSJeff Layton struct filename *from; 408791a27b2aSJeff Layton struct filename *to; 4088c6a94284SJeff Layton unsigned int lookup_flags = 0; 4089c6a94284SJeff Layton bool should_retry = false; 40902ad94ae6SAl Viro int error; 4091c6a94284SJeff Layton retry: 4092c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 409391a27b2aSJeff Layton if (IS_ERR(from)) { 409491a27b2aSJeff Layton error = PTR_ERR(from); 40951da177e4SLinus Torvalds goto exit; 409691a27b2aSJeff Layton } 40971da177e4SLinus Torvalds 4098c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 409991a27b2aSJeff Layton if (IS_ERR(to)) { 410091a27b2aSJeff Layton error = PTR_ERR(to); 41011da177e4SLinus Torvalds goto exit1; 410291a27b2aSJeff Layton } 41031da177e4SLinus Torvalds 41041da177e4SLinus Torvalds error = -EXDEV; 41054ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 41061da177e4SLinus Torvalds goto exit2; 41071da177e4SLinus Torvalds 41084ac91378SJan Blunck old_dir = oldnd.path.dentry; 41091da177e4SLinus Torvalds error = -EBUSY; 41101da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 41111da177e4SLinus Torvalds goto exit2; 41121da177e4SLinus Torvalds 41134ac91378SJan Blunck new_dir = newnd.path.dentry; 41141da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 41151da177e4SLinus Torvalds goto exit2; 41161da177e4SLinus Torvalds 4117c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4118c30dabfeSJan Kara if (error) 4119c30dabfeSJan Kara goto exit2; 4120c30dabfeSJan Kara 41210612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 41220612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 41234e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 41240612d9fbSOGAWA Hirofumi 41251da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 41261da177e4SLinus Torvalds 412749705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 41281da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 41291da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 41301da177e4SLinus Torvalds goto exit3; 41311da177e4SLinus Torvalds /* source must exist */ 41321da177e4SLinus Torvalds error = -ENOENT; 41331da177e4SLinus Torvalds if (!old_dentry->d_inode) 41341da177e4SLinus Torvalds goto exit4; 41351da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 41361da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 41371da177e4SLinus Torvalds error = -ENOTDIR; 41381da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 41391da177e4SLinus Torvalds goto exit4; 41401da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 41411da177e4SLinus Torvalds goto exit4; 41421da177e4SLinus Torvalds } 41431da177e4SLinus Torvalds /* source should not be ancestor of target */ 41441da177e4SLinus Torvalds error = -EINVAL; 41451da177e4SLinus Torvalds if (old_dentry == trap) 41461da177e4SLinus Torvalds goto exit4; 414749705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 41481da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41491da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 41501da177e4SLinus Torvalds goto exit4; 41511da177e4SLinus Torvalds /* target should not be an ancestor of source */ 41521da177e4SLinus Torvalds error = -ENOTEMPTY; 41531da177e4SLinus Torvalds if (new_dentry == trap) 41541da177e4SLinus Torvalds goto exit5; 41551da177e4SLinus Torvalds 4156be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 4157be6d3e56SKentaro Takeda &newnd.path, new_dentry); 4158be6d3e56SKentaro Takeda if (error) 4159c30dabfeSJan Kara goto exit5; 41601da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 41611da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 41621da177e4SLinus Torvalds exit5: 41631da177e4SLinus Torvalds dput(new_dentry); 41641da177e4SLinus Torvalds exit4: 41651da177e4SLinus Torvalds dput(old_dentry); 41661da177e4SLinus Torvalds exit3: 41671da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 4168c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 41691da177e4SLinus Torvalds exit2: 4170c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4171c6a94284SJeff Layton should_retry = true; 41721d957f9bSJan Blunck path_put(&newnd.path); 41732ad94ae6SAl Viro putname(to); 41741da177e4SLinus Torvalds exit1: 41751d957f9bSJan Blunck path_put(&oldnd.path); 41761da177e4SLinus Torvalds putname(from); 4177c6a94284SJeff Layton if (should_retry) { 4178c6a94284SJeff Layton should_retry = false; 4179c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4180c6a94284SJeff Layton goto retry; 4181c6a94284SJeff Layton } 41822ad94ae6SAl Viro exit: 41831da177e4SLinus Torvalds return error; 41841da177e4SLinus Torvalds } 41851da177e4SLinus Torvalds 4186a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 41875590ff0dSUlrich Drepper { 41885590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 41895590ff0dSUlrich Drepper } 41905590ff0dSUlrich Drepper 41911da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 41921da177e4SLinus Torvalds { 41931da177e4SLinus Torvalds int len; 41941da177e4SLinus Torvalds 41951da177e4SLinus Torvalds len = PTR_ERR(link); 41961da177e4SLinus Torvalds if (IS_ERR(link)) 41971da177e4SLinus Torvalds goto out; 41981da177e4SLinus Torvalds 41991da177e4SLinus Torvalds len = strlen(link); 42001da177e4SLinus Torvalds if (len > (unsigned) buflen) 42011da177e4SLinus Torvalds len = buflen; 42021da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 42031da177e4SLinus Torvalds len = -EFAULT; 42041da177e4SLinus Torvalds out: 42051da177e4SLinus Torvalds return len; 42061da177e4SLinus Torvalds } 42071da177e4SLinus Torvalds 42081da177e4SLinus Torvalds /* 42091da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 42101da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 42111da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 42121da177e4SLinus Torvalds */ 42131da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 42141da177e4SLinus Torvalds { 42151da177e4SLinus Torvalds struct nameidata nd; 4216cc314eefSLinus Torvalds void *cookie; 4217694a1764SMarcin Slusarz int res; 4218cc314eefSLinus Torvalds 42191da177e4SLinus Torvalds nd.depth = 0; 4220cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4221694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4222694a1764SMarcin Slusarz return PTR_ERR(cookie); 4223694a1764SMarcin Slusarz 4224694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 42251da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4226cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4227694a1764SMarcin Slusarz return res; 42281da177e4SLinus Torvalds } 42291da177e4SLinus Torvalds 42301da177e4SLinus Torvalds int vfs_follow_link(struct nameidata *nd, const char *link) 42311da177e4SLinus Torvalds { 42321da177e4SLinus Torvalds return __vfs_follow_link(nd, link); 42331da177e4SLinus Torvalds } 42341da177e4SLinus Torvalds 42351da177e4SLinus Torvalds /* get the link contents into pagecache */ 42361da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 42371da177e4SLinus Torvalds { 4238ebd09abbSDuane Griffin char *kaddr; 42391da177e4SLinus Torvalds struct page *page; 42401da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4241090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 42421da177e4SLinus Torvalds if (IS_ERR(page)) 42436fe6900eSNick Piggin return (char*)page; 42441da177e4SLinus Torvalds *ppage = page; 4245ebd09abbSDuane Griffin kaddr = kmap(page); 4246ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4247ebd09abbSDuane Griffin return kaddr; 42481da177e4SLinus Torvalds } 42491da177e4SLinus Torvalds 42501da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 42511da177e4SLinus Torvalds { 42521da177e4SLinus Torvalds struct page *page = NULL; 42531da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 42541da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 42551da177e4SLinus Torvalds if (page) { 42561da177e4SLinus Torvalds kunmap(page); 42571da177e4SLinus Torvalds page_cache_release(page); 42581da177e4SLinus Torvalds } 42591da177e4SLinus Torvalds return res; 42601da177e4SLinus Torvalds } 42611da177e4SLinus Torvalds 4262cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 42631da177e4SLinus Torvalds { 4264cc314eefSLinus Torvalds struct page *page = NULL; 42651da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4266cc314eefSLinus Torvalds return page; 42671da177e4SLinus Torvalds } 42681da177e4SLinus Torvalds 4269cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 42701da177e4SLinus Torvalds { 4271cc314eefSLinus Torvalds struct page *page = cookie; 4272cc314eefSLinus Torvalds 4273cc314eefSLinus Torvalds if (page) { 42741da177e4SLinus Torvalds kunmap(page); 42751da177e4SLinus Torvalds page_cache_release(page); 42761da177e4SLinus Torvalds } 42771da177e4SLinus Torvalds } 42781da177e4SLinus Torvalds 427954566b2cSNick Piggin /* 428054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 428154566b2cSNick Piggin */ 428254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 42831da177e4SLinus Torvalds { 42841da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 42850adb25d2SKirill Korotaev struct page *page; 4286afddba49SNick Piggin void *fsdata; 4287beb497abSDmitriy Monakhov int err; 42881da177e4SLinus Torvalds char *kaddr; 428954566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 429054566b2cSNick Piggin if (nofs) 429154566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 42921da177e4SLinus Torvalds 42937e53cac4SNeilBrown retry: 4294afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 429554566b2cSNick Piggin flags, &page, &fsdata); 42961da177e4SLinus Torvalds if (err) 4297afddba49SNick Piggin goto fail; 4298afddba49SNick Piggin 4299e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 43001da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4301e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4302afddba49SNick Piggin 4303afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4304afddba49SNick Piggin page, fsdata); 43051da177e4SLinus Torvalds if (err < 0) 43061da177e4SLinus Torvalds goto fail; 4307afddba49SNick Piggin if (err < len-1) 4308afddba49SNick Piggin goto retry; 4309afddba49SNick Piggin 43101da177e4SLinus Torvalds mark_inode_dirty(inode); 43111da177e4SLinus Torvalds return 0; 43121da177e4SLinus Torvalds fail: 43131da177e4SLinus Torvalds return err; 43141da177e4SLinus Torvalds } 43151da177e4SLinus Torvalds 43160adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 43170adb25d2SKirill Korotaev { 43180adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 431954566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 43200adb25d2SKirill Korotaev } 43210adb25d2SKirill Korotaev 432292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 43231da177e4SLinus Torvalds .readlink = generic_readlink, 43241da177e4SLinus Torvalds .follow_link = page_follow_link_light, 43251da177e4SLinus Torvalds .put_link = page_put_link, 43261da177e4SLinus Torvalds }; 43271da177e4SLinus Torvalds 43282d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 4329cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 43301da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 43311da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 4332f6d2ac5cSAl Viro EXPORT_SYMBOL(get_write_access); /* nfsd */ 43331da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 43341da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 43351da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 43361da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 43371da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 43380adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 43391da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 43401da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4341d1811465SAl Viro EXPORT_SYMBOL(kern_path); 434216f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 4343f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 43441da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 43451da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 43461da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_follow_link); 43471da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 43481da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 43491da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 43501da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 43511da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 43521da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 43531da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 43541da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 43551da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 43561da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 43571da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 4358