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 rcu_read_lock(); 48832a7991bSAl Viro } 48932a7991bSAl Viro 49032a7991bSAl Viro static inline void unlock_rcu_walk(void) 49132a7991bSAl Viro { 49232a7991bSAl Viro rcu_read_unlock(); 49332a7991bSAl Viro } 49432a7991bSAl Viro 49531e6b01fSNick Piggin /** 49619660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 49719660af7SAl Viro * @nd: nameidata pathwalk data 49819660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 49939191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 50031e6b01fSNick Piggin * 50119660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 50219660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 50319660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 50431e6b01fSNick Piggin */ 50519660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 50631e6b01fSNick Piggin { 50731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 50831e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 50931e6b01fSNick Piggin 51031e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 511e5c832d5SLinus Torvalds 512e5c832d5SLinus Torvalds /* 51348a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 51448a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 51548a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 51648a066e7SAl Viro * before returning. Do vfsmount first; if dentry 51748a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 51848a066e7SAl Viro * and rely on dput(NULL) being a no-op. 519e5c832d5SLinus Torvalds */ 52048a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 521e5c832d5SLinus Torvalds return -ECHILD; 522e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 52315570086SLinus Torvalds 52448a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 52548a066e7SAl Viro nd->path.dentry = NULL; 52648a066e7SAl Viro unlock_rcu_walk(); 52748a066e7SAl Viro return -ECHILD; 52848a066e7SAl Viro } 52948a066e7SAl Viro 53015570086SLinus Torvalds /* 53115570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 53215570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 53315570086SLinus Torvalds * 53415570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 53515570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 53615570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 53715570086SLinus Torvalds * since we checked the sequence number of the parent after we got 53815570086SLinus Torvalds * the child sequence number. So we know the parent must still 53915570086SLinus Torvalds * be valid if the child sequence number is still valid. 54015570086SLinus Torvalds */ 54119660af7SAl Viro if (!dentry) { 542e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 543e5c832d5SLinus Torvalds goto out; 54419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 54519660af7SAl Viro } else { 546e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 547e5c832d5SLinus Torvalds goto out; 548e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 549e5c832d5SLinus Torvalds goto drop_dentry; 55019660af7SAl Viro } 551e5c832d5SLinus Torvalds 552e5c832d5SLinus Torvalds /* 553e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 554e5c832d5SLinus Torvalds * still valid and get it if required. 555e5c832d5SLinus Torvalds */ 556e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 557e5c832d5SLinus Torvalds spin_lock(&fs->lock); 558e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 559e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 56031e6b01fSNick Piggin path_get(&nd->root); 56131e6b01fSNick Piggin spin_unlock(&fs->lock); 56231e6b01fSNick Piggin } 56331e6b01fSNick Piggin 56432a7991bSAl Viro unlock_rcu_walk(); 56531e6b01fSNick Piggin return 0; 56619660af7SAl Viro 567e5c832d5SLinus Torvalds unlock_and_drop_dentry: 56831e6b01fSNick Piggin spin_unlock(&fs->lock); 569e5c832d5SLinus Torvalds drop_dentry: 570e5c832d5SLinus Torvalds unlock_rcu_walk(); 571e5c832d5SLinus Torvalds dput(dentry); 572d0d27277SLinus Torvalds goto drop_root_mnt; 573e5c832d5SLinus Torvalds out: 574e5c832d5SLinus Torvalds unlock_rcu_walk(); 575d0d27277SLinus Torvalds drop_root_mnt: 576d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 577d0d27277SLinus Torvalds nd->root.mnt = NULL; 57831e6b01fSNick Piggin return -ECHILD; 57931e6b01fSNick Piggin } 58031e6b01fSNick Piggin 5814ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 58234286d66SNick Piggin { 5834ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 58434286d66SNick Piggin } 58534286d66SNick Piggin 5869f1fafeeSAl Viro /** 5879f1fafeeSAl Viro * complete_walk - successful completion of path walk 5889f1fafeeSAl Viro * @nd: pointer nameidata 58939159de2SJeff Layton * 5909f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 5919f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 5929f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 5939f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 5949f1fafeeSAl Viro * need to drop nd->path. 59539159de2SJeff Layton */ 5969f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 59739159de2SJeff Layton { 59816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 59939159de2SJeff Layton int status; 60039159de2SJeff Layton 6019f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6029f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6039f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6049f1fafeeSAl Viro nd->root.mnt = NULL; 60515570086SLinus Torvalds 60648a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 60748a066e7SAl Viro unlock_rcu_walk(); 60848a066e7SAl Viro return -ECHILD; 60948a066e7SAl Viro } 610e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 61132a7991bSAl Viro unlock_rcu_walk(); 61248a066e7SAl Viro mntput(nd->path.mnt); 6139f1fafeeSAl Viro return -ECHILD; 6149f1fafeeSAl Viro } 615e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 616e5c832d5SLinus Torvalds unlock_rcu_walk(); 617e5c832d5SLinus Torvalds dput(dentry); 61848a066e7SAl Viro mntput(nd->path.mnt); 619e5c832d5SLinus Torvalds return -ECHILD; 620e5c832d5SLinus Torvalds } 62132a7991bSAl Viro unlock_rcu_walk(); 6229f1fafeeSAl Viro } 6239f1fafeeSAl Viro 62416c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 62539159de2SJeff Layton return 0; 62639159de2SJeff Layton 627ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 62816c2cd71SAl Viro return 0; 62916c2cd71SAl Viro 630ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 63139159de2SJeff Layton if (status > 0) 63239159de2SJeff Layton return 0; 63339159de2SJeff Layton 63416c2cd71SAl Viro if (!status) 63539159de2SJeff Layton status = -ESTALE; 63616c2cd71SAl Viro 6379f1fafeeSAl Viro path_put(&nd->path); 63839159de2SJeff Layton return status; 63939159de2SJeff Layton } 64039159de2SJeff Layton 6412a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6422a737871SAl Viro { 643f7ad3c6bSMiklos Szeredi if (!nd->root.mnt) 644f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6452a737871SAl Viro } 6462a737871SAl Viro 6476de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6486de88d72SAl Viro 64931e6b01fSNick Piggin static __always_inline void set_root_rcu(struct nameidata *nd) 65031e6b01fSNick Piggin { 65131e6b01fSNick Piggin if (!nd->root.mnt) { 65231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 653c28cc364SNick Piggin unsigned seq; 654c28cc364SNick Piggin 655c28cc364SNick Piggin do { 656c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 65731e6b01fSNick Piggin nd->root = fs->root; 658c1530019STim Chen nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 659c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 66031e6b01fSNick Piggin } 66131e6b01fSNick Piggin } 66231e6b01fSNick Piggin 6631d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 664051d3812SIan Kent { 665051d3812SIan Kent dput(path->dentry); 6664ac91378SJan Blunck if (path->mnt != nd->path.mnt) 667051d3812SIan Kent mntput(path->mnt); 668051d3812SIan Kent } 669051d3812SIan Kent 6707b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6717b9337aaSNick Piggin struct nameidata *nd) 672051d3812SIan Kent { 67331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6744ac91378SJan Blunck dput(nd->path.dentry); 67531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6764ac91378SJan Blunck mntput(nd->path.mnt); 6779a229683SHuang Shijie } 67831e6b01fSNick Piggin nd->path.mnt = path->mnt; 6794ac91378SJan Blunck nd->path.dentry = path->dentry; 680051d3812SIan Kent } 681051d3812SIan Kent 682b5fb63c1SChristoph Hellwig /* 683b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 684b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 685b5fb63c1SChristoph Hellwig */ 686b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 687b5fb63c1SChristoph Hellwig { 688b5fb63c1SChristoph Hellwig path_put(&nd->path); 689b5fb63c1SChristoph Hellwig 690b5fb63c1SChristoph Hellwig nd->path = *path; 691b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 692b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 693b5fb63c1SChristoph Hellwig } 694b5fb63c1SChristoph Hellwig 695574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 696574197e0SAl Viro { 697574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 6986d7b5aaeSAl Viro if (inode->i_op->put_link) 699574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 700574197e0SAl Viro path_put(link); 701574197e0SAl Viro } 702574197e0SAl Viro 703561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 704561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 705800179c9SKees Cook 706800179c9SKees Cook /** 707800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 708800179c9SKees Cook * @link: The path of the symlink 70955852635SRandy Dunlap * @nd: nameidata pathwalk data 710800179c9SKees Cook * 711800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 712800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 713800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 714800179c9SKees Cook * processes from failing races against path names that may change out 715800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 716800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 717800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 718800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 719800179c9SKees Cook * 720800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 721800179c9SKees Cook */ 722800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 723800179c9SKees Cook { 724800179c9SKees Cook const struct inode *inode; 725800179c9SKees Cook const struct inode *parent; 726800179c9SKees Cook 727800179c9SKees Cook if (!sysctl_protected_symlinks) 728800179c9SKees Cook return 0; 729800179c9SKees Cook 730800179c9SKees Cook /* Allowed if owner and follower match. */ 731800179c9SKees Cook inode = link->dentry->d_inode; 73281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 733800179c9SKees Cook return 0; 734800179c9SKees Cook 735800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 736800179c9SKees Cook parent = nd->path.dentry->d_inode; 737800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 738800179c9SKees Cook return 0; 739800179c9SKees Cook 740800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 74181abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 742800179c9SKees Cook return 0; 743800179c9SKees Cook 744ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 745800179c9SKees Cook path_put_conditional(link, nd); 746800179c9SKees Cook path_put(&nd->path); 747800179c9SKees Cook return -EACCES; 748800179c9SKees Cook } 749800179c9SKees Cook 750800179c9SKees Cook /** 751800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 752800179c9SKees Cook * @inode: the source inode to hardlink from 753800179c9SKees Cook * 754800179c9SKees Cook * Return false if at least one of the following conditions: 755800179c9SKees Cook * - inode is not a regular file 756800179c9SKees Cook * - inode is setuid 757800179c9SKees Cook * - inode is setgid and group-exec 758800179c9SKees Cook * - access failure for read and write 759800179c9SKees Cook * 760800179c9SKees Cook * Otherwise returns true. 761800179c9SKees Cook */ 762800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 763800179c9SKees Cook { 764800179c9SKees Cook umode_t mode = inode->i_mode; 765800179c9SKees Cook 766800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 767800179c9SKees Cook if (!S_ISREG(mode)) 768800179c9SKees Cook return false; 769800179c9SKees Cook 770800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 771800179c9SKees Cook if (mode & S_ISUID) 772800179c9SKees Cook return false; 773800179c9SKees Cook 774800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 775800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 776800179c9SKees Cook return false; 777800179c9SKees Cook 778800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 779800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 780800179c9SKees Cook return false; 781800179c9SKees Cook 782800179c9SKees Cook return true; 783800179c9SKees Cook } 784800179c9SKees Cook 785800179c9SKees Cook /** 786800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 787800179c9SKees Cook * @link: the source to hardlink from 788800179c9SKees Cook * 789800179c9SKees Cook * Block hardlink when all of: 790800179c9SKees Cook * - sysctl_protected_hardlinks enabled 791800179c9SKees Cook * - fsuid does not match inode 792800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 793800179c9SKees Cook * - not CAP_FOWNER 794800179c9SKees Cook * 795800179c9SKees Cook * Returns 0 if successful, -ve on error. 796800179c9SKees Cook */ 797800179c9SKees Cook static int may_linkat(struct path *link) 798800179c9SKees Cook { 799800179c9SKees Cook const struct cred *cred; 800800179c9SKees Cook struct inode *inode; 801800179c9SKees Cook 802800179c9SKees Cook if (!sysctl_protected_hardlinks) 803800179c9SKees Cook return 0; 804800179c9SKees Cook 805800179c9SKees Cook cred = current_cred(); 806800179c9SKees Cook inode = link->dentry->d_inode; 807800179c9SKees Cook 808800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 809800179c9SKees Cook * otherwise, it must be a safe source. 810800179c9SKees Cook */ 81181abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 812800179c9SKees Cook capable(CAP_FOWNER)) 813800179c9SKees Cook return 0; 814800179c9SKees Cook 815a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 816800179c9SKees Cook return -EPERM; 817800179c9SKees Cook } 818800179c9SKees Cook 819def4af30SAl Viro static __always_inline int 820574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 8211da177e4SLinus Torvalds { 8227b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8236d7b5aaeSAl Viro int error; 8246d7b5aaeSAl Viro char *s; 8251da177e4SLinus Torvalds 826844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 827844a3917SAl Viro 8280e794589SAl Viro if (link->mnt == nd->path.mnt) 8290e794589SAl Viro mntget(link->mnt); 8300e794589SAl Viro 8316d7b5aaeSAl Viro error = -ELOOP; 8326d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8336d7b5aaeSAl Viro goto out_put_nd_path; 8346d7b5aaeSAl Viro 835574197e0SAl Viro cond_resched(); 836574197e0SAl Viro current->total_link_count++; 837574197e0SAl Viro 83868ac1234SAl Viro touch_atime(link); 8391da177e4SLinus Torvalds nd_set_link(nd, NULL); 840cd4e91d3SAl Viro 84136f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8426d7b5aaeSAl Viro if (error) 8436d7b5aaeSAl Viro goto out_put_nd_path; 84436f3b4f6SAl Viro 84586acdca1SAl Viro nd->last_type = LAST_BIND; 846def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 847def4af30SAl Viro error = PTR_ERR(*p); 8486d7b5aaeSAl Viro if (IS_ERR(*p)) 849408ef013SChristoph Hellwig goto out_put_nd_path; 8506d7b5aaeSAl Viro 851cc314eefSLinus Torvalds error = 0; 8526d7b5aaeSAl Viro s = nd_get_link(nd); 8536d7b5aaeSAl Viro if (s) { 854443ed254SAl Viro if (unlikely(IS_ERR(s))) { 855443ed254SAl Viro path_put(&nd->path); 856443ed254SAl Viro put_link(nd, link, *p); 857443ed254SAl Viro return PTR_ERR(s); 858443ed254SAl Viro } 859443ed254SAl Viro if (*s == '/') { 860443ed254SAl Viro set_root(nd); 861443ed254SAl Viro path_put(&nd->path); 862443ed254SAl Viro nd->path = nd->root; 863443ed254SAl Viro path_get(&nd->root); 864443ed254SAl Viro nd->flags |= LOOKUP_JUMPED; 865443ed254SAl Viro } 866443ed254SAl Viro nd->inode = nd->path.dentry->d_inode; 867443ed254SAl Viro error = link_path_walk(s, nd); 8686d7b5aaeSAl Viro if (unlikely(error)) 8696d7b5aaeSAl Viro put_link(nd, link, *p); 870b5fb63c1SChristoph Hellwig } 8716d7b5aaeSAl Viro 8726d7b5aaeSAl Viro return error; 8736d7b5aaeSAl Viro 8746d7b5aaeSAl Viro out_put_nd_path: 87598f6ef64SArnd Bergmann *p = NULL; 8766d7b5aaeSAl Viro path_put(&nd->path); 8776d7b5aaeSAl Viro path_put(link); 8781da177e4SLinus Torvalds return error; 8791da177e4SLinus Torvalds } 8801da177e4SLinus Torvalds 88131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 88231e6b01fSNick Piggin { 8830714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8840714a533SAl Viro struct mount *parent; 88531e6b01fSNick Piggin struct dentry *mountpoint; 88631e6b01fSNick Piggin 8870714a533SAl Viro parent = mnt->mnt_parent; 8880714a533SAl Viro if (&parent->mnt == path->mnt) 88931e6b01fSNick Piggin return 0; 890a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 89131e6b01fSNick Piggin path->dentry = mountpoint; 8920714a533SAl Viro path->mnt = &parent->mnt; 89331e6b01fSNick Piggin return 1; 89431e6b01fSNick Piggin } 89531e6b01fSNick Piggin 896f015f126SDavid Howells /* 897f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 898f015f126SDavid Howells * 899f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 900f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 901f015f126SDavid Howells * Up is towards /. 902f015f126SDavid Howells * 903f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 904f015f126SDavid Howells * root. 905f015f126SDavid Howells */ 906bab77ebfSAl Viro int follow_up(struct path *path) 9071da177e4SLinus Torvalds { 9080714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9090714a533SAl Viro struct mount *parent; 9101da177e4SLinus Torvalds struct dentry *mountpoint; 91199b7db7bSNick Piggin 91248a066e7SAl Viro read_seqlock_excl(&mount_lock); 9130714a533SAl Viro parent = mnt->mnt_parent; 9143c0a6163SAl Viro if (parent == mnt) { 91548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9161da177e4SLinus Torvalds return 0; 9171da177e4SLinus Torvalds } 9180714a533SAl Viro mntget(&parent->mnt); 919a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 92048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 921bab77ebfSAl Viro dput(path->dentry); 922bab77ebfSAl Viro path->dentry = mountpoint; 923bab77ebfSAl Viro mntput(path->mnt); 9240714a533SAl Viro path->mnt = &parent->mnt; 9251da177e4SLinus Torvalds return 1; 9261da177e4SLinus Torvalds } 9271da177e4SLinus Torvalds 928b5c84bf6SNick Piggin /* 9299875cf80SDavid Howells * Perform an automount 9309875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9319875cf80SDavid Howells * were called with. 9321da177e4SLinus Torvalds */ 9339875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9349875cf80SDavid Howells bool *need_mntput) 93531e6b01fSNick Piggin { 9369875cf80SDavid Howells struct vfsmount *mnt; 937ea5b778aSDavid Howells int err; 9389875cf80SDavid Howells 9399875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9409875cf80SDavid Howells return -EREMOTE; 9419875cf80SDavid Howells 9420ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9430ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9440ec26fd0SMiklos Szeredi * the name. 9450ec26fd0SMiklos Szeredi * 9460ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9475a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9480ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9490ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9500ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9510ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9525a30d8a2SDavid Howells */ 9535a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 954d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9555a30d8a2SDavid Howells path->dentry->d_inode) 9569875cf80SDavid Howells return -EISDIR; 9570ec26fd0SMiklos Szeredi 9589875cf80SDavid Howells current->total_link_count++; 9599875cf80SDavid Howells if (current->total_link_count >= 40) 9609875cf80SDavid Howells return -ELOOP; 9619875cf80SDavid Howells 9629875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9639875cf80SDavid Howells if (IS_ERR(mnt)) { 9649875cf80SDavid Howells /* 9659875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9669875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9679875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9689875cf80SDavid Howells * 9699875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9709875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9719875cf80SDavid Howells * the path is inaccessible and we should say so. 9729875cf80SDavid Howells */ 97349084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9749875cf80SDavid Howells return -EREMOTE; 9759875cf80SDavid Howells return PTR_ERR(mnt); 97631e6b01fSNick Piggin } 977ea5b778aSDavid Howells 9789875cf80SDavid Howells if (!mnt) /* mount collision */ 9799875cf80SDavid Howells return 0; 9809875cf80SDavid Howells 9818aef1884SAl Viro if (!*need_mntput) { 9828aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9838aef1884SAl Viro mntget(path->mnt); 9848aef1884SAl Viro *need_mntput = true; 9858aef1884SAl Viro } 98619a167afSAl Viro err = finish_automount(mnt, path); 987ea5b778aSDavid Howells 988ea5b778aSDavid Howells switch (err) { 989ea5b778aSDavid Howells case -EBUSY: 990ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 99119a167afSAl Viro return 0; 992ea5b778aSDavid Howells case 0: 9938aef1884SAl Viro path_put(path); 9949875cf80SDavid Howells path->mnt = mnt; 9959875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9969875cf80SDavid Howells return 0; 99719a167afSAl Viro default: 99819a167afSAl Viro return err; 9999875cf80SDavid Howells } 100019a167afSAl Viro 1001ea5b778aSDavid Howells } 10029875cf80SDavid Howells 10039875cf80SDavid Howells /* 10049875cf80SDavid Howells * Handle a dentry that is managed in some way. 1005cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10069875cf80SDavid Howells * - Flagged as mountpoint 10079875cf80SDavid Howells * - Flagged as automount point 10089875cf80SDavid Howells * 10099875cf80SDavid Howells * This may only be called in refwalk mode. 10109875cf80SDavid Howells * 10119875cf80SDavid Howells * Serialization is taken care of in namespace.c 10129875cf80SDavid Howells */ 10139875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10149875cf80SDavid Howells { 10158aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10169875cf80SDavid Howells unsigned managed; 10179875cf80SDavid Howells bool need_mntput = false; 10188aef1884SAl Viro int ret = 0; 10199875cf80SDavid Howells 10209875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10219875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10229875cf80SDavid Howells * the components of that value change under us */ 10239875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10249875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10259875cf80SDavid Howells unlikely(managed != 0)) { 1026cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1027cc53ce53SDavid Howells * being held. */ 1028cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1029cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1030cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10311aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1032cc53ce53SDavid Howells if (ret < 0) 10338aef1884SAl Viro break; 1034cc53ce53SDavid Howells } 1035cc53ce53SDavid Howells 10369875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10379875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10389875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10399875cf80SDavid Howells if (mounted) { 10409875cf80SDavid Howells dput(path->dentry); 10419875cf80SDavid Howells if (need_mntput) 1042463ffb2eSAl Viro mntput(path->mnt); 1043463ffb2eSAl Viro path->mnt = mounted; 1044463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10459875cf80SDavid Howells need_mntput = true; 10469875cf80SDavid Howells continue; 1047463ffb2eSAl Viro } 1048463ffb2eSAl Viro 10499875cf80SDavid Howells /* Something is mounted on this dentry in another 10509875cf80SDavid Howells * namespace and/or whatever was mounted there in this 105148a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 105248a066e7SAl Viro * get it */ 10531da177e4SLinus Torvalds } 10549875cf80SDavid Howells 10559875cf80SDavid Howells /* Handle an automount point */ 10569875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10579875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10589875cf80SDavid Howells if (ret < 0) 10598aef1884SAl Viro break; 10609875cf80SDavid Howells continue; 10619875cf80SDavid Howells } 10629875cf80SDavid Howells 10639875cf80SDavid Howells /* We didn't change the current path point */ 10649875cf80SDavid Howells break; 10659875cf80SDavid Howells } 10668aef1884SAl Viro 10678aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10688aef1884SAl Viro mntput(path->mnt); 10698aef1884SAl Viro if (ret == -EISDIR) 10708aef1884SAl Viro ret = 0; 1071a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10721da177e4SLinus Torvalds } 10731da177e4SLinus Torvalds 1074cc53ce53SDavid Howells int follow_down_one(struct path *path) 10751da177e4SLinus Torvalds { 10761da177e4SLinus Torvalds struct vfsmount *mounted; 10771da177e4SLinus Torvalds 10781c755af4SAl Viro mounted = lookup_mnt(path); 10791da177e4SLinus Torvalds if (mounted) { 10809393bd07SAl Viro dput(path->dentry); 10819393bd07SAl Viro mntput(path->mnt); 10829393bd07SAl Viro path->mnt = mounted; 10839393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10841da177e4SLinus Torvalds return 1; 10851da177e4SLinus Torvalds } 10861da177e4SLinus Torvalds return 0; 10871da177e4SLinus Torvalds } 10881da177e4SLinus Torvalds 108962a7375eSIan Kent static inline bool managed_dentry_might_block(struct dentry *dentry) 109062a7375eSIan Kent { 109162a7375eSIan Kent return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && 109262a7375eSIan Kent dentry->d_op->d_manage(dentry, true) < 0); 109362a7375eSIan Kent } 109462a7375eSIan Kent 10959875cf80SDavid Howells /* 1096287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1097287548e4SAl Viro * we meet a managed dentry that would need blocking. 10989875cf80SDavid Howells */ 10999875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1100287548e4SAl Viro struct inode **inode) 11019875cf80SDavid Howells { 110262a7375eSIan Kent for (;;) { 1103c7105365SAl Viro struct mount *mounted; 110462a7375eSIan Kent /* 110562a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 110662a7375eSIan Kent * that wants to block transit. 110762a7375eSIan Kent */ 1108287548e4SAl Viro if (unlikely(managed_dentry_might_block(path->dentry))) 1109ab90911fSDavid Howells return false; 111062a7375eSIan Kent 111162a7375eSIan Kent if (!d_mountpoint(path->dentry)) 111262a7375eSIan Kent break; 111362a7375eSIan Kent 1114474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11159875cf80SDavid Howells if (!mounted) 11169875cf80SDavid Howells break; 1117c7105365SAl Viro path->mnt = &mounted->mnt; 1118c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1119a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11209875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 112159430262SLinus Torvalds /* 112259430262SLinus Torvalds * Update the inode too. We don't need to re-check the 112359430262SLinus Torvalds * dentry sequence number here after this d_inode read, 112459430262SLinus Torvalds * because a mount-point is always pinned. 112559430262SLinus Torvalds */ 112659430262SLinus Torvalds *inode = path->dentry->d_inode; 11279875cf80SDavid Howells } 11289875cf80SDavid Howells return true; 11299875cf80SDavid Howells } 11309875cf80SDavid Howells 1131dea39376SAl Viro static void follow_mount_rcu(struct nameidata *nd) 1132287548e4SAl Viro { 1133dea39376SAl Viro while (d_mountpoint(nd->path.dentry)) { 1134c7105365SAl Viro struct mount *mounted; 1135474279dcSAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1136287548e4SAl Viro if (!mounted) 1137287548e4SAl Viro break; 1138c7105365SAl Viro nd->path.mnt = &mounted->mnt; 1139c7105365SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 1140dea39376SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1141287548e4SAl Viro } 1142287548e4SAl Viro } 1143287548e4SAl Viro 114431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 114531e6b01fSNick Piggin { 114631e6b01fSNick Piggin set_root_rcu(nd); 114731e6b01fSNick Piggin 114831e6b01fSNick Piggin while (1) { 114931e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 115031e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 115131e6b01fSNick Piggin break; 115231e6b01fSNick Piggin } 115331e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 115431e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 115531e6b01fSNick Piggin struct dentry *parent = old->d_parent; 115631e6b01fSNick Piggin unsigned seq; 115731e6b01fSNick Piggin 115831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 115931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1160ef7562d5SAl Viro goto failed; 116131e6b01fSNick Piggin nd->path.dentry = parent; 116231e6b01fSNick Piggin nd->seq = seq; 116331e6b01fSNick Piggin break; 116431e6b01fSNick Piggin } 116531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 116631e6b01fSNick Piggin break; 116731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 116831e6b01fSNick Piggin } 1169dea39376SAl Viro follow_mount_rcu(nd); 1170dea39376SAl Viro nd->inode = nd->path.dentry->d_inode; 117131e6b01fSNick Piggin return 0; 1172ef7562d5SAl Viro 1173ef7562d5SAl Viro failed: 1174ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11755b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1176ef7562d5SAl Viro nd->root.mnt = NULL; 117732a7991bSAl Viro unlock_rcu_walk(); 1178ef7562d5SAl Viro return -ECHILD; 117931e6b01fSNick Piggin } 118031e6b01fSNick Piggin 11819875cf80SDavid Howells /* 1182cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1183cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1184cc53ce53SDavid Howells * caller is permitted to proceed or not. 1185cc53ce53SDavid Howells */ 11867cc90cc3SAl Viro int follow_down(struct path *path) 1187cc53ce53SDavid Howells { 1188cc53ce53SDavid Howells unsigned managed; 1189cc53ce53SDavid Howells int ret; 1190cc53ce53SDavid Howells 1191cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1192cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1193cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1194cc53ce53SDavid Howells * being held. 1195cc53ce53SDavid Howells * 1196cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1197cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1198cc53ce53SDavid Howells * other than its daemon the right to mount on its 1199cc53ce53SDavid Howells * superstructure. 1200cc53ce53SDavid Howells * 1201cc53ce53SDavid Howells * The filesystem may sleep at this point. 1202cc53ce53SDavid Howells */ 1203cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1204cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1205cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1206ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12071aed3e42SAl Viro path->dentry, false); 1208cc53ce53SDavid Howells if (ret < 0) 1209cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1210cc53ce53SDavid Howells } 1211cc53ce53SDavid Howells 1212cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1213cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1214cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1215cc53ce53SDavid Howells if (!mounted) 1216cc53ce53SDavid Howells break; 1217cc53ce53SDavid Howells dput(path->dentry); 1218cc53ce53SDavid Howells mntput(path->mnt); 1219cc53ce53SDavid Howells path->mnt = mounted; 1220cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1221cc53ce53SDavid Howells continue; 1222cc53ce53SDavid Howells } 1223cc53ce53SDavid Howells 1224cc53ce53SDavid Howells /* Don't handle automount points here */ 1225cc53ce53SDavid Howells break; 1226cc53ce53SDavid Howells } 1227cc53ce53SDavid Howells return 0; 1228cc53ce53SDavid Howells } 1229cc53ce53SDavid Howells 1230cc53ce53SDavid Howells /* 12319875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12329875cf80SDavid Howells */ 12339875cf80SDavid Howells static void follow_mount(struct path *path) 12349875cf80SDavid Howells { 12359875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12369875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12379875cf80SDavid Howells if (!mounted) 12389875cf80SDavid Howells break; 12399875cf80SDavid Howells dput(path->dentry); 12409875cf80SDavid Howells mntput(path->mnt); 12419875cf80SDavid Howells path->mnt = mounted; 12429875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12439875cf80SDavid Howells } 12449875cf80SDavid Howells } 12459875cf80SDavid Howells 124631e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12471da177e4SLinus Torvalds { 12482a737871SAl Viro set_root(nd); 1249e518ddb7SAndreas Mohr 12501da177e4SLinus Torvalds while(1) { 12514ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12521da177e4SLinus Torvalds 12532a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12542a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12551da177e4SLinus Torvalds break; 12561da177e4SLinus Torvalds } 12574ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12583088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12593088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12601da177e4SLinus Torvalds dput(old); 12611da177e4SLinus Torvalds break; 12621da177e4SLinus Torvalds } 12633088dd70SAl Viro if (!follow_up(&nd->path)) 12641da177e4SLinus Torvalds break; 12651da177e4SLinus Torvalds } 126679ed0226SAl Viro follow_mount(&nd->path); 126731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12681da177e4SLinus Torvalds } 12691da177e4SLinus Torvalds 12701da177e4SLinus Torvalds /* 1271bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1272bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1273bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1274bad61189SMiklos Szeredi * 1275bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1276baa03890SNick Piggin */ 1277bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1278201f956eSAl Viro unsigned int flags, bool *need_lookup) 1279baa03890SNick Piggin { 1280baa03890SNick Piggin struct dentry *dentry; 1281bad61189SMiklos Szeredi int error; 1282baa03890SNick Piggin 1283bad61189SMiklos Szeredi *need_lookup = false; 1284bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1285bad61189SMiklos Szeredi if (dentry) { 128639e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1287201f956eSAl Viro error = d_revalidate(dentry, flags); 1288bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1289bad61189SMiklos Szeredi if (error < 0) { 1290bad61189SMiklos Szeredi dput(dentry); 1291bad61189SMiklos Szeredi return ERR_PTR(error); 1292bad61189SMiklos Szeredi } else if (!d_invalidate(dentry)) { 1293bad61189SMiklos Szeredi dput(dentry); 1294bad61189SMiklos Szeredi dentry = NULL; 1295bad61189SMiklos Szeredi } 1296bad61189SMiklos Szeredi } 1297bad61189SMiklos Szeredi } 1298bad61189SMiklos Szeredi } 1299baa03890SNick Piggin 1300bad61189SMiklos Szeredi if (!dentry) { 1301bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1302baa03890SNick Piggin if (unlikely(!dentry)) 1303baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1304baa03890SNick Piggin 1305bad61189SMiklos Szeredi *need_lookup = true; 1306baa03890SNick Piggin } 1307baa03890SNick Piggin return dentry; 1308baa03890SNick Piggin } 1309baa03890SNick Piggin 1310baa03890SNick Piggin /* 1311bad61189SMiklos Szeredi * Call i_op->lookup on the dentry. The dentry must be negative but may be 1312bad61189SMiklos Szeredi * hashed if it was pouplated with DCACHE_NEED_LOOKUP. 1313bad61189SMiklos Szeredi * 1314bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 131544396f4bSJosef Bacik */ 1316bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 131772bd866aSAl Viro unsigned int flags) 131844396f4bSJosef Bacik { 131944396f4bSJosef Bacik struct dentry *old; 132044396f4bSJosef Bacik 132144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1322bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1323e188dc02SMiklos Szeredi dput(dentry); 132444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1325e188dc02SMiklos Szeredi } 132644396f4bSJosef Bacik 132772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 132844396f4bSJosef Bacik if (unlikely(old)) { 132944396f4bSJosef Bacik dput(dentry); 133044396f4bSJosef Bacik dentry = old; 133144396f4bSJosef Bacik } 133244396f4bSJosef Bacik return dentry; 133344396f4bSJosef Bacik } 133444396f4bSJosef Bacik 1335a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 133672bd866aSAl Viro struct dentry *base, unsigned int flags) 1337a3255546SAl Viro { 1338bad61189SMiklos Szeredi bool need_lookup; 1339a3255546SAl Viro struct dentry *dentry; 1340a3255546SAl Viro 134172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1342bad61189SMiklos Szeredi if (!need_lookup) 1343a3255546SAl Viro return dentry; 1344bad61189SMiklos Szeredi 134572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1346a3255546SAl Viro } 1347a3255546SAl Viro 134844396f4bSJosef Bacik /* 13491da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13501da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13511da177e4SLinus Torvalds * It _is_ time-critical. 13521da177e4SLinus Torvalds */ 1353e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 135431e6b01fSNick Piggin struct path *path, struct inode **inode) 13551da177e4SLinus Torvalds { 13564ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 135731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13585a18fff2SAl Viro int need_reval = 1; 13595a18fff2SAl Viro int status = 1; 13609875cf80SDavid Howells int err; 13619875cf80SDavid Howells 13623cac260aSAl Viro /* 1363b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1364b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1365b04f784eSNick Piggin * do the non-racy lookup, below. 1366b04f784eSNick Piggin */ 136731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 136831e6b01fSNick Piggin unsigned seq; 1369da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13705a18fff2SAl Viro if (!dentry) 13715a18fff2SAl Viro goto unlazy; 13725a18fff2SAl Viro 137312f8ad4bSLinus Torvalds /* 137412f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 137512f8ad4bSLinus Torvalds * the dentry name information from lookup. 137612f8ad4bSLinus Torvalds */ 137712f8ad4bSLinus Torvalds *inode = dentry->d_inode; 137812f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 137912f8ad4bSLinus Torvalds return -ECHILD; 138012f8ad4bSLinus Torvalds 138112f8ad4bSLinus Torvalds /* 138212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 138312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 138412f8ad4bSLinus Torvalds * 138512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 138612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 138712f8ad4bSLinus Torvalds */ 138831e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 138931e6b01fSNick Piggin return -ECHILD; 139031e6b01fSNick Piggin nd->seq = seq; 13915a18fff2SAl Viro 139224643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 13934ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 13945a18fff2SAl Viro if (unlikely(status <= 0)) { 13955a18fff2SAl Viro if (status != -ECHILD) 13965a18fff2SAl Viro need_reval = 0; 13975a18fff2SAl Viro goto unlazy; 13985a18fff2SAl Viro } 139924643087SAl Viro } 140031e6b01fSNick Piggin path->mnt = mnt; 140131e6b01fSNick Piggin path->dentry = dentry; 1402d6e9bd25SAl Viro if (unlikely(!__follow_mount_rcu(nd, path, inode))) 1403d6e9bd25SAl Viro goto unlazy; 1404d6e9bd25SAl Viro if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) 1405d6e9bd25SAl Viro goto unlazy; 14069875cf80SDavid Howells return 0; 14075a18fff2SAl Viro unlazy: 140819660af7SAl Viro if (unlazy_walk(nd, dentry)) 14095a18fff2SAl Viro return -ECHILD; 14105a18fff2SAl Viro } else { 1411e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 141224643087SAl Viro } 14135a18fff2SAl Viro 141481e6f520SAl Viro if (unlikely(!dentry)) 141581e6f520SAl Viro goto need_lookup; 14165a18fff2SAl Viro 14175a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14184ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14195a18fff2SAl Viro if (unlikely(status <= 0)) { 14205a18fff2SAl Viro if (status < 0) { 14215a18fff2SAl Viro dput(dentry); 14225a18fff2SAl Viro return status; 14235a18fff2SAl Viro } 14245a18fff2SAl Viro if (!d_invalidate(dentry)) { 14255a18fff2SAl Viro dput(dentry); 142681e6f520SAl Viro goto need_lookup; 14275a18fff2SAl Viro } 14285a18fff2SAl Viro } 1429697f514dSMiklos Szeredi 14301da177e4SLinus Torvalds path->mnt = mnt; 14311da177e4SLinus Torvalds path->dentry = dentry; 14329875cf80SDavid Howells err = follow_managed(path, nd->flags); 143389312214SIan Kent if (unlikely(err < 0)) { 143489312214SIan Kent path_put_conditional(path, nd); 14359875cf80SDavid Howells return err; 143689312214SIan Kent } 1437a3fbbde7SAl Viro if (err) 1438a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 143931e6b01fSNick Piggin *inode = path->dentry->d_inode; 14401da177e4SLinus Torvalds return 0; 144181e6f520SAl Viro 144281e6f520SAl Viro need_lookup: 1443697f514dSMiklos Szeredi return 1; 1444697f514dSMiklos Szeredi } 1445697f514dSMiklos Szeredi 1446697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1447cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1448697f514dSMiklos Szeredi { 1449697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1450697f514dSMiklos Szeredi int err; 1451697f514dSMiklos Szeredi 1452697f514dSMiklos Szeredi parent = nd->path.dentry; 145381e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 145481e6f520SAl Viro 145581e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1456cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 145781e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 145881e6f520SAl Viro if (IS_ERR(dentry)) 145981e6f520SAl Viro return PTR_ERR(dentry); 1460697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1461697f514dSMiklos Szeredi path->dentry = dentry; 1462697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1463697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1464697f514dSMiklos Szeredi path_put_conditional(path, nd); 1465697f514dSMiklos Szeredi return err; 1466697f514dSMiklos Szeredi } 1467697f514dSMiklos Szeredi if (err) 1468697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1469697f514dSMiklos Szeredi return 0; 14701da177e4SLinus Torvalds } 14711da177e4SLinus Torvalds 147252094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 147352094c8aSAl Viro { 147452094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14754ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 147652094c8aSAl Viro if (err != -ECHILD) 147752094c8aSAl Viro return err; 147819660af7SAl Viro if (unlazy_walk(nd, NULL)) 147952094c8aSAl Viro return -ECHILD; 148052094c8aSAl Viro } 14814ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 148252094c8aSAl Viro } 148352094c8aSAl Viro 14849856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 14859856fa1bSAl Viro { 14869856fa1bSAl Viro if (type == LAST_DOTDOT) { 14879856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 14889856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 14899856fa1bSAl Viro return -ECHILD; 14909856fa1bSAl Viro } else 14919856fa1bSAl Viro follow_dotdot(nd); 14929856fa1bSAl Viro } 14939856fa1bSAl Viro return 0; 14949856fa1bSAl Viro } 14959856fa1bSAl Viro 1496951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1497951361f9SAl Viro { 1498951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1499951361f9SAl Viro path_put(&nd->path); 1500951361f9SAl Viro } else { 1501951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15025b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1503951361f9SAl Viro nd->root.mnt = NULL; 150432a7991bSAl Viro unlock_rcu_walk(); 1505951361f9SAl Viro } 1506951361f9SAl Viro } 1507951361f9SAl Viro 15083ddcd056SLinus Torvalds /* 15093ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15103ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15113ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15123ddcd056SLinus Torvalds * for the common case. 15133ddcd056SLinus Torvalds */ 15147813b94aSLinus Torvalds static inline int should_follow_link(struct inode *inode, int follow) 15153ddcd056SLinus Torvalds { 15163ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { 15173ddcd056SLinus Torvalds if (likely(inode->i_op->follow_link)) 15183ddcd056SLinus Torvalds return follow; 15193ddcd056SLinus Torvalds 15203ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 15213ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 15223ddcd056SLinus Torvalds inode->i_opflags |= IOP_NOFOLLOW; 15233ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 15243ddcd056SLinus Torvalds } 15253ddcd056SLinus Torvalds return 0; 15263ddcd056SLinus Torvalds } 15273ddcd056SLinus Torvalds 1528ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 152921b9b073SAl Viro int follow) 1530ce57dfc1SAl Viro { 1531ce57dfc1SAl Viro struct inode *inode; 1532ce57dfc1SAl Viro int err; 1533ce57dfc1SAl Viro /* 1534ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1535ce57dfc1SAl Viro * to be able to know about the current root directory and 1536ce57dfc1SAl Viro * parent relationships. 1537ce57dfc1SAl Viro */ 153821b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 153921b9b073SAl Viro return handle_dots(nd, nd->last_type); 1540e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1541ce57dfc1SAl Viro if (unlikely(err)) { 1542697f514dSMiklos Szeredi if (err < 0) 1543697f514dSMiklos Szeredi goto out_err; 1544697f514dSMiklos Szeredi 1545cc2a5271SAl Viro err = lookup_slow(nd, path); 1546697f514dSMiklos Szeredi if (err < 0) 1547697f514dSMiklos Szeredi goto out_err; 1548697f514dSMiklos Szeredi 1549697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1550ce57dfc1SAl Viro } 1551697f514dSMiklos Szeredi err = -ENOENT; 1552697f514dSMiklos Szeredi if (!inode) 1553697f514dSMiklos Szeredi goto out_path_put; 1554697f514dSMiklos Szeredi 15557813b94aSLinus Torvalds if (should_follow_link(inode, follow)) { 155619660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 155719660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1558697f514dSMiklos Szeredi err = -ECHILD; 1559697f514dSMiklos Szeredi goto out_err; 156019660af7SAl Viro } 156119660af7SAl Viro } 1562ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1563ce57dfc1SAl Viro return 1; 1564ce57dfc1SAl Viro } 1565ce57dfc1SAl Viro path_to_nameidata(path, nd); 1566ce57dfc1SAl Viro nd->inode = inode; 1567ce57dfc1SAl Viro return 0; 1568697f514dSMiklos Szeredi 1569697f514dSMiklos Szeredi out_path_put: 1570697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1571697f514dSMiklos Szeredi out_err: 1572697f514dSMiklos Szeredi terminate_walk(nd); 1573697f514dSMiklos Szeredi return err; 1574ce57dfc1SAl Viro } 1575ce57dfc1SAl Viro 15761da177e4SLinus Torvalds /* 1577b356379aSAl Viro * This limits recursive symlink follows to 8, while 1578b356379aSAl Viro * limiting consecutive symlinks to 40. 1579b356379aSAl Viro * 1580b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1581b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1582b356379aSAl Viro */ 1583b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1584b356379aSAl Viro { 1585b356379aSAl Viro int res; 1586b356379aSAl Viro 1587b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1588b356379aSAl Viro path_put_conditional(path, nd); 1589b356379aSAl Viro path_put(&nd->path); 1590b356379aSAl Viro return -ELOOP; 1591b356379aSAl Viro } 15921a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1593b356379aSAl Viro 1594b356379aSAl Viro nd->depth++; 1595b356379aSAl Viro current->link_count++; 1596b356379aSAl Viro 1597b356379aSAl Viro do { 1598b356379aSAl Viro struct path link = *path; 1599b356379aSAl Viro void *cookie; 1600574197e0SAl Viro 1601574197e0SAl Viro res = follow_link(&link, nd, &cookie); 16026d7b5aaeSAl Viro if (res) 16036d7b5aaeSAl Viro break; 160421b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1605574197e0SAl Viro put_link(nd, &link, cookie); 1606b356379aSAl Viro } while (res > 0); 1607b356379aSAl Viro 1608b356379aSAl Viro current->link_count--; 1609b356379aSAl Viro nd->depth--; 1610b356379aSAl Viro return res; 1611b356379aSAl Viro } 1612b356379aSAl Viro 1613b356379aSAl Viro /* 16143ddcd056SLinus Torvalds * We really don't want to look at inode->i_op->lookup 16153ddcd056SLinus Torvalds * when we don't have to. So we keep a cache bit in 16163ddcd056SLinus Torvalds * the inode ->i_opflags field that says "yes, we can 16173ddcd056SLinus Torvalds * do lookup on this inode". 16183ddcd056SLinus Torvalds */ 16193ddcd056SLinus Torvalds static inline int can_lookup(struct inode *inode) 16203ddcd056SLinus Torvalds { 16213ddcd056SLinus Torvalds if (likely(inode->i_opflags & IOP_LOOKUP)) 16223ddcd056SLinus Torvalds return 1; 16233ddcd056SLinus Torvalds if (likely(!inode->i_op->lookup)) 16243ddcd056SLinus Torvalds return 0; 16253ddcd056SLinus Torvalds 16263ddcd056SLinus Torvalds /* We do this once for the lifetime of the inode */ 16273ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 16283ddcd056SLinus Torvalds inode->i_opflags |= IOP_LOOKUP; 16293ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 16303ddcd056SLinus Torvalds return 1; 16313ddcd056SLinus Torvalds } 16323ddcd056SLinus Torvalds 1633bfcfaa77SLinus Torvalds /* 1634bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1635bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1636bfcfaa77SLinus Torvalds * 1637bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1638bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1639bfcfaa77SLinus Torvalds * fast. 1640bfcfaa77SLinus Torvalds * 1641bfcfaa77SLinus Torvalds * - Little-endian machines (so that we can generate the mask 1642bfcfaa77SLinus Torvalds * of low bytes efficiently). Again, we *could* do a byte 1643bfcfaa77SLinus Torvalds * swapping load on big-endian architectures if that is not 1644bfcfaa77SLinus Torvalds * expensive enough to make the optimization worthless. 1645bfcfaa77SLinus Torvalds * 1646bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1647bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1648bfcfaa77SLinus Torvalds * crossing operation. 1649bfcfaa77SLinus Torvalds * 1650bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1651bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1652bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1653bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1654bfcfaa77SLinus Torvalds */ 1655bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1656bfcfaa77SLinus Torvalds 1657f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1658bfcfaa77SLinus Torvalds 1659f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1660bfcfaa77SLinus Torvalds 1661bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1662bfcfaa77SLinus Torvalds { 1663bfcfaa77SLinus Torvalds hash += hash >> (8*sizeof(int)); 1664bfcfaa77SLinus Torvalds return hash; 1665bfcfaa77SLinus Torvalds } 1666bfcfaa77SLinus Torvalds 1667bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1668bfcfaa77SLinus Torvalds 1669bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1670bfcfaa77SLinus Torvalds 1671bfcfaa77SLinus Torvalds #endif 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1674bfcfaa77SLinus Torvalds { 1675bfcfaa77SLinus Torvalds unsigned long a, mask; 1676bfcfaa77SLinus Torvalds unsigned long hash = 0; 1677bfcfaa77SLinus Torvalds 1678bfcfaa77SLinus Torvalds for (;;) { 1679e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1680bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1681bfcfaa77SLinus Torvalds break; 1682bfcfaa77SLinus Torvalds hash += a; 1683f132c5beSAl Viro hash *= 9; 1684bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1685bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1686bfcfaa77SLinus Torvalds if (!len) 1687bfcfaa77SLinus Torvalds goto done; 1688bfcfaa77SLinus Torvalds } 1689bfcfaa77SLinus Torvalds mask = ~(~0ul << len*8); 1690bfcfaa77SLinus Torvalds hash += mask & a; 1691bfcfaa77SLinus Torvalds done: 1692bfcfaa77SLinus Torvalds return fold_hash(hash); 1693bfcfaa77SLinus Torvalds } 1694bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1695bfcfaa77SLinus Torvalds 1696bfcfaa77SLinus Torvalds /* 1697bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1698bfcfaa77SLinus Torvalds * return the length of the component; 1699bfcfaa77SLinus Torvalds */ 1700bfcfaa77SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1701bfcfaa77SLinus Torvalds { 170236126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 170336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1704bfcfaa77SLinus Torvalds 1705bfcfaa77SLinus Torvalds hash = a = 0; 1706bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1707bfcfaa77SLinus Torvalds do { 1708bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1709bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1710e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 171136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 171236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1713bfcfaa77SLinus Torvalds 171436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 171536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 171636126f8fSLinus Torvalds 171736126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 171836126f8fSLinus Torvalds 171936126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 1720bfcfaa77SLinus Torvalds *hashp = fold_hash(hash); 1721bfcfaa77SLinus Torvalds 172236126f8fSLinus Torvalds return len + find_zero(mask); 1723bfcfaa77SLinus Torvalds } 1724bfcfaa77SLinus Torvalds 1725bfcfaa77SLinus Torvalds #else 1726bfcfaa77SLinus Torvalds 17270145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17280145acc2SLinus Torvalds { 17290145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17300145acc2SLinus Torvalds while (len--) 17310145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17320145acc2SLinus Torvalds return end_name_hash(hash); 17330145acc2SLinus Torvalds } 1734ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17350145acc2SLinus Torvalds 17363ddcd056SLinus Torvalds /* 1737200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1738200e9ef7SLinus Torvalds * one character. 1739200e9ef7SLinus Torvalds */ 1740200e9ef7SLinus Torvalds static inline unsigned long hash_name(const char *name, unsigned int *hashp) 1741200e9ef7SLinus Torvalds { 1742200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1743200e9ef7SLinus Torvalds unsigned long len = 0, c; 1744200e9ef7SLinus Torvalds 1745200e9ef7SLinus Torvalds c = (unsigned char)*name; 1746200e9ef7SLinus Torvalds do { 1747200e9ef7SLinus Torvalds len++; 1748200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1749200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1750200e9ef7SLinus Torvalds } while (c && c != '/'); 1751200e9ef7SLinus Torvalds *hashp = end_name_hash(hash); 1752200e9ef7SLinus Torvalds return len; 1753200e9ef7SLinus Torvalds } 1754200e9ef7SLinus Torvalds 1755bfcfaa77SLinus Torvalds #endif 1756bfcfaa77SLinus Torvalds 1757200e9ef7SLinus Torvalds /* 17581da177e4SLinus Torvalds * Name resolution. 1759ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1760ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17611da177e4SLinus Torvalds * 1762ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1763ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17641da177e4SLinus Torvalds */ 17656de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17661da177e4SLinus Torvalds { 17671da177e4SLinus Torvalds struct path next; 17681da177e4SLinus Torvalds int err; 17691da177e4SLinus Torvalds 17701da177e4SLinus Torvalds while (*name=='/') 17711da177e4SLinus Torvalds name++; 17721da177e4SLinus Torvalds if (!*name) 1773086e183aSAl Viro return 0; 17741da177e4SLinus Torvalds 17751da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17761da177e4SLinus Torvalds for(;;) { 17771da177e4SLinus Torvalds struct qstr this; 1778200e9ef7SLinus Torvalds long len; 1779fe479a58SAl Viro int type; 17801da177e4SLinus Torvalds 178152094c8aSAl Viro err = may_lookup(nd); 17821da177e4SLinus Torvalds if (err) 17831da177e4SLinus Torvalds break; 17841da177e4SLinus Torvalds 1785200e9ef7SLinus Torvalds len = hash_name(name, &this.hash); 17861da177e4SLinus Torvalds this.name = name; 1787200e9ef7SLinus Torvalds this.len = len; 17881da177e4SLinus Torvalds 1789fe479a58SAl Viro type = LAST_NORM; 1790200e9ef7SLinus Torvalds if (name[0] == '.') switch (len) { 1791fe479a58SAl Viro case 2: 1792200e9ef7SLinus Torvalds if (name[1] == '.') { 1793fe479a58SAl Viro type = LAST_DOTDOT; 179416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 179516c2cd71SAl Viro } 1796fe479a58SAl Viro break; 1797fe479a58SAl Viro case 1: 1798fe479a58SAl Viro type = LAST_DOT; 1799fe479a58SAl Viro } 18005a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18015a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180216c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18035a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1804da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18055a202bcdSAl Viro if (err < 0) 18065a202bcdSAl Viro break; 18075a202bcdSAl Viro } 18085a202bcdSAl Viro } 1809fe479a58SAl Viro 18105f4a6a69SAl Viro nd->last = this; 18115f4a6a69SAl Viro nd->last_type = type; 18125f4a6a69SAl Viro 1813200e9ef7SLinus Torvalds if (!name[len]) 18145f4a6a69SAl Viro return 0; 1815200e9ef7SLinus Torvalds /* 1816200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1817200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1818200e9ef7SLinus Torvalds */ 1819200e9ef7SLinus Torvalds do { 1820200e9ef7SLinus Torvalds len++; 1821200e9ef7SLinus Torvalds } while (unlikely(name[len] == '/')); 1822200e9ef7SLinus Torvalds if (!name[len]) 18235f4a6a69SAl Viro return 0; 18245f4a6a69SAl Viro 1825200e9ef7SLinus Torvalds name += len; 18261da177e4SLinus Torvalds 182721b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1828ce57dfc1SAl Viro if (err < 0) 1829ce57dfc1SAl Viro return err; 1830fe479a58SAl Viro 1831ce57dfc1SAl Viro if (err) { 1832b356379aSAl Viro err = nested_symlink(&next, nd); 18331da177e4SLinus Torvalds if (err) 1834a7472babSAl Viro return err; 183531e6b01fSNick Piggin } 18365f4a6a69SAl Viro if (!can_lookup(nd->inode)) { 18373ddcd056SLinus Torvalds err = -ENOTDIR; 18383ddcd056SLinus Torvalds break; 18395f4a6a69SAl Viro } 1840ce57dfc1SAl Viro } 1841951361f9SAl Viro terminate_walk(nd); 18421da177e4SLinus Torvalds return err; 18431da177e4SLinus Torvalds } 18441da177e4SLinus Torvalds 184570e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 184670e9b357SAl Viro struct nameidata *nd, struct file **fp) 184731e6b01fSNick Piggin { 184831e6b01fSNick Piggin int retval = 0; 184931e6b01fSNick Piggin 185031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 185116c2cd71SAl Viro nd->flags = flags | LOOKUP_JUMPED; 185231e6b01fSNick Piggin nd->depth = 0; 18535b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 18545b6ca027SAl Viro struct inode *inode = nd->root.dentry->d_inode; 185573d049a4SAl Viro if (*name) { 1856741b7c3fSAl Viro if (!can_lookup(inode)) 18575b6ca027SAl Viro return -ENOTDIR; 18585b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18595b6ca027SAl Viro if (retval) 18605b6ca027SAl Viro return retval; 186173d049a4SAl Viro } 18625b6ca027SAl Viro nd->path = nd->root; 18635b6ca027SAl Viro nd->inode = inode; 18645b6ca027SAl Viro if (flags & LOOKUP_RCU) { 186532a7991bSAl Viro lock_rcu_walk(); 18665b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 186748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18685b6ca027SAl Viro } else { 18695b6ca027SAl Viro path_get(&nd->path); 18705b6ca027SAl Viro } 18715b6ca027SAl Viro return 0; 18725b6ca027SAl Viro } 18735b6ca027SAl Viro 187431e6b01fSNick Piggin nd->root.mnt = NULL; 187531e6b01fSNick Piggin 187648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 187731e6b01fSNick Piggin if (*name=='/') { 1878e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 187932a7991bSAl Viro lock_rcu_walk(); 1880e41f7d4eSAl Viro set_root_rcu(nd); 1881e41f7d4eSAl Viro } else { 1882e41f7d4eSAl Viro set_root(nd); 1883e41f7d4eSAl Viro path_get(&nd->root); 1884e41f7d4eSAl Viro } 188531e6b01fSNick Piggin nd->path = nd->root; 188631e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1887e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 188831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1889c28cc364SNick Piggin unsigned seq; 189031e6b01fSNick Piggin 189132a7991bSAl Viro lock_rcu_walk(); 189231e6b01fSNick Piggin 1893c28cc364SNick Piggin do { 1894c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 189531e6b01fSNick Piggin nd->path = fs->pwd; 1896c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1897c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1898e41f7d4eSAl Viro } else { 1899e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1900e41f7d4eSAl Viro } 190131e6b01fSNick Piggin } else { 1902582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19032903ff01SAl Viro struct fd f = fdget_raw(dfd); 190431e6b01fSNick Piggin struct dentry *dentry; 190531e6b01fSNick Piggin 19062903ff01SAl Viro if (!f.file) 19072903ff01SAl Viro return -EBADF; 190831e6b01fSNick Piggin 19092903ff01SAl Viro dentry = f.file->f_path.dentry; 191031e6b01fSNick Piggin 1911f52e0c11SAl Viro if (*name) { 1912741b7c3fSAl Viro if (!can_lookup(dentry->d_inode)) { 19132903ff01SAl Viro fdput(f); 19142903ff01SAl Viro return -ENOTDIR; 1915f52e0c11SAl Viro } 19162903ff01SAl Viro } 19172903ff01SAl Viro 19182903ff01SAl Viro nd->path = f.file->f_path; 1919e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19202903ff01SAl Viro if (f.need_put) 19212903ff01SAl Viro *fp = f.file; 1922c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 192332a7991bSAl Viro lock_rcu_walk(); 19245590ff0dSUlrich Drepper } else { 19252903ff01SAl Viro path_get(&nd->path); 19262903ff01SAl Viro fdput(f); 19271da177e4SLinus Torvalds } 1928e41f7d4eSAl Viro } 1929e41f7d4eSAl Viro 193031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19319b4a9b14SAl Viro return 0; 19329b4a9b14SAl Viro } 19339b4a9b14SAl Viro 1934bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1935bd92d7feSAl Viro { 1936bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1937bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1938bd92d7feSAl Viro 1939bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 194021b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1941bd92d7feSAl Viro } 1942bd92d7feSAl Viro 19439b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1944ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19459b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19469b4a9b14SAl Viro { 194770e9b357SAl Viro struct file *base = NULL; 1948bd92d7feSAl Viro struct path path; 1949bd92d7feSAl Viro int err; 195031e6b01fSNick Piggin 195131e6b01fSNick Piggin /* 195231e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 195331e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 195431e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 195531e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 195631e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 195731e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 195831e6b01fSNick Piggin * analogue, foo_rcu(). 195931e6b01fSNick Piggin * 196031e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 196131e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 196231e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 196331e6b01fSNick Piggin * be able to complete). 196431e6b01fSNick Piggin */ 1965bd92d7feSAl Viro err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); 1966ee0827cdSAl Viro 1967bd92d7feSAl Viro if (unlikely(err)) 1968bd92d7feSAl Viro return err; 1969ee0827cdSAl Viro 1970ee0827cdSAl Viro current->total_link_count = 0; 1971bd92d7feSAl Viro err = link_path_walk(name, nd); 1972bd92d7feSAl Viro 1973bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1974bd92d7feSAl Viro err = lookup_last(nd, &path); 1975bd92d7feSAl Viro while (err > 0) { 1976bd92d7feSAl Viro void *cookie; 1977bd92d7feSAl Viro struct path link = path; 1978800179c9SKees Cook err = may_follow_link(&link, nd); 1979800179c9SKees Cook if (unlikely(err)) 1980800179c9SKees Cook break; 1981bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 1982574197e0SAl Viro err = follow_link(&link, nd, &cookie); 19836d7b5aaeSAl Viro if (err) 19846d7b5aaeSAl Viro break; 1985bd92d7feSAl Viro err = lookup_last(nd, &path); 1986574197e0SAl Viro put_link(nd, &link, cookie); 1987bd92d7feSAl Viro } 1988bd92d7feSAl Viro } 1989ee0827cdSAl Viro 19909f1fafeeSAl Viro if (!err) 19919f1fafeeSAl Viro err = complete_walk(nd); 1992bd92d7feSAl Viro 1993bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 199405252901SAl Viro if (!can_lookup(nd->inode)) { 1995bd92d7feSAl Viro path_put(&nd->path); 1996bd23a539SAl Viro err = -ENOTDIR; 1997bd92d7feSAl Viro } 1998bd92d7feSAl Viro } 199916c2cd71SAl Viro 200070e9b357SAl Viro if (base) 200170e9b357SAl Viro fput(base); 2002ee0827cdSAl Viro 20035b6ca027SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 200431e6b01fSNick Piggin path_put(&nd->root); 200531e6b01fSNick Piggin nd->root.mnt = NULL; 200631e6b01fSNick Piggin } 2007bd92d7feSAl Viro return err; 200831e6b01fSNick Piggin } 200931e6b01fSNick Piggin 2010873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2011873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2012873f1eedSJeff Layton { 2013873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 2014873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2015873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 2016873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2017873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 2018873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 2019873f1eedSJeff Layton 2020873f1eedSJeff Layton if (likely(!retval)) 2021adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2022873f1eedSJeff Layton return retval; 2023873f1eedSJeff Layton } 2024873f1eedSJeff Layton 2025ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 2026ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 2027ee0827cdSAl Viro { 2028873f1eedSJeff Layton struct filename filename = { .name = name }; 2029ee0827cdSAl Viro 2030873f1eedSJeff Layton return filename_lookup(dfd, &filename, flags, nd); 20311da177e4SLinus Torvalds } 20321da177e4SLinus Torvalds 203379714f72SAl Viro /* does lookup, returns the object with parent locked */ 203479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20355590ff0dSUlrich Drepper { 203679714f72SAl Viro struct nameidata nd; 203779714f72SAl Viro struct dentry *d; 203879714f72SAl Viro int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); 203979714f72SAl Viro if (err) 204079714f72SAl Viro return ERR_PTR(err); 204179714f72SAl Viro if (nd.last_type != LAST_NORM) { 204279714f72SAl Viro path_put(&nd.path); 204379714f72SAl Viro return ERR_PTR(-EINVAL); 204479714f72SAl Viro } 204579714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20461e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 204779714f72SAl Viro if (IS_ERR(d)) { 204879714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 204979714f72SAl Viro path_put(&nd.path); 205079714f72SAl Viro return d; 205179714f72SAl Viro } 205279714f72SAl Viro *path = nd.path; 205379714f72SAl Viro return d; 20545590ff0dSUlrich Drepper } 20555590ff0dSUlrich Drepper 2056d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2057d1811465SAl Viro { 2058d1811465SAl Viro struct nameidata nd; 2059d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2060d1811465SAl Viro if (!res) 2061d1811465SAl Viro *path = nd.path; 2062d1811465SAl Viro return res; 2063d1811465SAl Viro } 2064d1811465SAl Viro 206516f18200SJosef 'Jeff' Sipek /** 206616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 206716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 206816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 206916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 207016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2071e0a01249SAl Viro * @path: pointer to struct path to fill 207216f18200SJosef 'Jeff' Sipek */ 207316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 207416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2075e0a01249SAl Viro struct path *path) 207616f18200SJosef 'Jeff' Sipek { 2077e0a01249SAl Viro struct nameidata nd; 2078e0a01249SAl Viro int err; 2079e0a01249SAl Viro nd.root.dentry = dentry; 2080e0a01249SAl Viro nd.root.mnt = mnt; 2081e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 20825b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2083e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2084e0a01249SAl Viro if (!err) 2085e0a01249SAl Viro *path = nd.path; 2086e0a01249SAl Viro return err; 208716f18200SJosef 'Jeff' Sipek } 208816f18200SJosef 'Jeff' Sipek 2089057f6c01SJames Morris /* 2090057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2091057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2092057f6c01SJames Morris * SMP-safe. 2093057f6c01SJames Morris */ 2094a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 20951da177e4SLinus Torvalds { 209672bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 20971da177e4SLinus Torvalds } 20981da177e4SLinus Torvalds 2099eead1911SChristoph Hellwig /** 2100a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2101eead1911SChristoph Hellwig * @name: pathname component to lookup 2102eead1911SChristoph Hellwig * @base: base directory to lookup from 2103eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2104eead1911SChristoph Hellwig * 2105a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2106a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2107eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2108eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2109eead1911SChristoph Hellwig */ 2110057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2111057f6c01SJames Morris { 2112057f6c01SJames Morris struct qstr this; 21136a96ba54SAl Viro unsigned int c; 2114cda309deSMiklos Szeredi int err; 2115057f6c01SJames Morris 21162f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21172f9092e1SDavid Woodhouse 21186a96ba54SAl Viro this.name = name; 21196a96ba54SAl Viro this.len = len; 21200145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21216a96ba54SAl Viro if (!len) 21226a96ba54SAl Viro return ERR_PTR(-EACCES); 21236a96ba54SAl Viro 212421d8a15aSAl Viro if (unlikely(name[0] == '.')) { 212521d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 212621d8a15aSAl Viro return ERR_PTR(-EACCES); 212721d8a15aSAl Viro } 212821d8a15aSAl Viro 21296a96ba54SAl Viro while (len--) { 21306a96ba54SAl Viro c = *(const unsigned char *)name++; 21316a96ba54SAl Viro if (c == '/' || c == '\0') 21326a96ba54SAl Viro return ERR_PTR(-EACCES); 21336a96ba54SAl Viro } 21345a202bcdSAl Viro /* 21355a202bcdSAl Viro * See if the low-level filesystem might want 21365a202bcdSAl Viro * to use its own hash.. 21375a202bcdSAl Viro */ 21385a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2139da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21405a202bcdSAl Viro if (err < 0) 21415a202bcdSAl Viro return ERR_PTR(err); 21425a202bcdSAl Viro } 2143eead1911SChristoph Hellwig 2144cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2145cda309deSMiklos Szeredi if (err) 2146cda309deSMiklos Szeredi return ERR_PTR(err); 2147cda309deSMiklos Szeredi 214872bd866aSAl Viro return __lookup_hash(&this, base, 0); 2149057f6c01SJames Morris } 2150057f6c01SJames Morris 21511fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21521fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21531da177e4SLinus Torvalds { 21542d8f3038SAl Viro struct nameidata nd; 215591a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21561da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21571da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21582d8f3038SAl Viro 21592d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21602d8f3038SAl Viro 2161873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21621da177e4SLinus Torvalds putname(tmp); 21632d8f3038SAl Viro if (!err) 21642d8f3038SAl Viro *path = nd.path; 21651da177e4SLinus Torvalds } 21661da177e4SLinus Torvalds return err; 21671da177e4SLinus Torvalds } 21681da177e4SLinus Torvalds 21691fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21701fa1e7f6SAndy Whitcroft struct path *path) 21711fa1e7f6SAndy Whitcroft { 2172f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21731fa1e7f6SAndy Whitcroft } 21741fa1e7f6SAndy Whitcroft 2175873f1eedSJeff Layton /* 2176873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2177873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2178873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2179873f1eedSJeff Layton * path-walking is complete. 2180873f1eedSJeff Layton */ 218191a27b2aSJeff Layton static struct filename * 21829e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 21839e790bd6SJeff Layton unsigned int flags) 21842ad94ae6SAl Viro { 218591a27b2aSJeff Layton struct filename *s = getname(path); 21862ad94ae6SAl Viro int error; 21872ad94ae6SAl Viro 21889e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 21899e790bd6SJeff Layton flags &= LOOKUP_REVAL; 21909e790bd6SJeff Layton 21912ad94ae6SAl Viro if (IS_ERR(s)) 219291a27b2aSJeff Layton return s; 21932ad94ae6SAl Viro 21949e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 219591a27b2aSJeff Layton if (error) { 21962ad94ae6SAl Viro putname(s); 219791a27b2aSJeff Layton return ERR_PTR(error); 219891a27b2aSJeff Layton } 21992ad94ae6SAl Viro 220091a27b2aSJeff Layton return s; 22012ad94ae6SAl Viro } 22022ad94ae6SAl Viro 22038033426eSJeff Layton /** 2204197df04cSAl Viro * mountpoint_last - look up last component for umount 22058033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22068033426eSJeff Layton * @path: pointer to container for result 22078033426eSJeff Layton * 22088033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22098033426eSJeff Layton * need to resolve the path without doing any revalidation. 22108033426eSJeff Layton * 22118033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22128033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22138033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22148033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22158033426eSJeff Layton * bogus and it doesn't exist. 22168033426eSJeff Layton * 22178033426eSJeff Layton * Returns: 22188033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22198033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22208033426eSJeff Layton * put in this case. 22218033426eSJeff Layton * 22228033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22238033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22248033426eSJeff Layton * The nd->path reference will also be put. 22258033426eSJeff Layton * 22268033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22278033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22288033426eSJeff Layton * to the link, and nd->path will *not* be put. 22298033426eSJeff Layton */ 22308033426eSJeff Layton static int 2231197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22328033426eSJeff Layton { 22338033426eSJeff Layton int error = 0; 22348033426eSJeff Layton struct dentry *dentry; 22358033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22368033426eSJeff Layton 223735759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 223835759521SAl Viro if (nd->flags & LOOKUP_RCU) { 223935759521SAl Viro if (unlazy_walk(nd, NULL)) { 22408033426eSJeff Layton error = -ECHILD; 224135759521SAl Viro goto out; 224235759521SAl Viro } 22438033426eSJeff Layton } 22448033426eSJeff Layton 22458033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22468033426eSJeff Layton 22478033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22488033426eSJeff Layton error = handle_dots(nd, nd->last_type); 224935759521SAl Viro if (error) 225035759521SAl Viro goto out; 22518033426eSJeff Layton dentry = dget(nd->path.dentry); 225235759521SAl Viro goto done; 22538033426eSJeff Layton } 22548033426eSJeff Layton 22558033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22568033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22578033426eSJeff Layton if (!dentry) { 22588033426eSJeff Layton /* 22598033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22608033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22618033426eSJeff Layton * path doesn't actually point to a mounted dentry. 22628033426eSJeff Layton */ 22638033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22648033426eSJeff Layton if (!dentry) { 22658033426eSJeff Layton error = -ENOMEM; 2266bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 226735759521SAl Viro goto out; 22688033426eSJeff Layton } 226935759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 227035759521SAl Viro error = PTR_ERR(dentry); 2271bcceeebaSDave Jones if (IS_ERR(dentry)) { 2272bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 227335759521SAl Viro goto out; 22748033426eSJeff Layton } 2275bcceeebaSDave Jones } 22768033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 22778033426eSJeff Layton 227835759521SAl Viro done: 22798033426eSJeff Layton if (!dentry->d_inode) { 22808033426eSJeff Layton error = -ENOENT; 22818033426eSJeff Layton dput(dentry); 228235759521SAl Viro goto out; 228335759521SAl Viro } 22848033426eSJeff Layton path->dentry = dentry; 22858033426eSJeff Layton path->mnt = mntget(nd->path.mnt); 228635759521SAl Viro if (should_follow_link(dentry->d_inode, nd->flags & LOOKUP_FOLLOW)) 22878033426eSJeff Layton return 1; 22888033426eSJeff Layton follow_mount(path); 228935759521SAl Viro error = 0; 229035759521SAl Viro out: 22918033426eSJeff Layton terminate_walk(nd); 22928033426eSJeff Layton return error; 22938033426eSJeff Layton } 22948033426eSJeff Layton 22958033426eSJeff Layton /** 2296197df04cSAl Viro * path_mountpoint - look up a path to be umounted 22978033426eSJeff Layton * @dfd: directory file descriptor to start walk from 22988033426eSJeff Layton * @name: full pathname to walk 22998033426eSJeff Layton * @flags: lookup flags 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 2305197df04cSAl Viro path_mountpoint(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 2320197df04cSAl Viro err = mountpoint_last(&nd, path); 23218033426eSJeff Layton while (err > 0) { 23228033426eSJeff Layton void *cookie; 23238033426eSJeff Layton struct path link = *path; 23248033426eSJeff Layton err = may_follow_link(&link, &nd); 23258033426eSJeff Layton if (unlikely(err)) 23268033426eSJeff Layton break; 23278033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 23288033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 23298033426eSJeff Layton if (err) 23308033426eSJeff Layton break; 2331197df04cSAl Viro err = mountpoint_last(&nd, path); 23328033426eSJeff Layton put_link(&nd, &link, cookie); 23338033426eSJeff Layton } 23348033426eSJeff Layton out: 23358033426eSJeff Layton if (base) 23368033426eSJeff Layton fput(base); 23378033426eSJeff Layton 23388033426eSJeff Layton if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT)) 23398033426eSJeff Layton path_put(&nd.root); 23408033426eSJeff Layton 23418033426eSJeff Layton return err; 23428033426eSJeff Layton } 23438033426eSJeff Layton 23442d864651SAl Viro static int 23452d864651SAl Viro filename_mountpoint(int dfd, struct filename *s, struct path *path, 23462d864651SAl Viro unsigned int flags) 23472d864651SAl Viro { 23482d864651SAl Viro int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); 23492d864651SAl Viro if (unlikely(error == -ECHILD)) 23502d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags); 23512d864651SAl Viro if (unlikely(error == -ESTALE)) 23522d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); 23532d864651SAl Viro if (likely(!error)) 23542d864651SAl Viro audit_inode(s, path->dentry, 0); 23552d864651SAl Viro return error; 23562d864651SAl Viro } 23572d864651SAl Viro 23588033426eSJeff Layton /** 2359197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 23608033426eSJeff Layton * @dfd: directory file descriptor 23618033426eSJeff Layton * @name: pathname from userland 23628033426eSJeff Layton * @flags: lookup flags 23638033426eSJeff Layton * @path: pointer to container to hold result 23648033426eSJeff Layton * 23658033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23668033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23678033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23688033426eSJeff Layton * and avoid revalidating the last component. 23698033426eSJeff Layton * 23708033426eSJeff Layton * Returns 0 and populates "path" on success. 23718033426eSJeff Layton */ 23728033426eSJeff Layton int 2373197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 23748033426eSJeff Layton struct path *path) 23758033426eSJeff Layton { 23768033426eSJeff Layton struct filename *s = getname(name); 23778033426eSJeff Layton int error; 23788033426eSJeff Layton if (IS_ERR(s)) 23798033426eSJeff Layton return PTR_ERR(s); 23802d864651SAl Viro error = filename_mountpoint(dfd, s, path, flags); 23818033426eSJeff Layton putname(s); 23828033426eSJeff Layton return error; 23838033426eSJeff Layton } 23848033426eSJeff Layton 23852d864651SAl Viro int 23862d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 23872d864651SAl Viro unsigned int flags) 23882d864651SAl Viro { 23892d864651SAl Viro struct filename s = {.name = name}; 23902d864651SAl Viro return filename_mountpoint(dfd, &s, path, flags); 23912d864651SAl Viro } 23922d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 23932d864651SAl Viro 23941da177e4SLinus Torvalds /* 23951da177e4SLinus Torvalds * It's inline, so penalty for filesystems that don't use sticky bit is 23961da177e4SLinus Torvalds * minimal. 23971da177e4SLinus Torvalds */ 23981da177e4SLinus Torvalds static inline int check_sticky(struct inode *dir, struct inode *inode) 23991da177e4SLinus Torvalds { 24008e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2401da9592edSDavid Howells 24021da177e4SLinus Torvalds if (!(dir->i_mode & S_ISVTX)) 24031da177e4SLinus Torvalds return 0; 24048e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24051da177e4SLinus Torvalds return 0; 24068e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24071da177e4SLinus Torvalds return 0; 24081a48e2acSEric W. Biederman return !inode_capable(inode, CAP_FOWNER); 24091da177e4SLinus Torvalds } 24101da177e4SLinus Torvalds 24111da177e4SLinus Torvalds /* 24121da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24131da177e4SLinus Torvalds * whether the type of victim is right. 24141da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24151da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24161da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24171da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24181da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24191da177e4SLinus Torvalds * a. be owner of dir, or 24201da177e4SLinus Torvalds * b. be owner of victim, or 24211da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24221da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24231da177e4SLinus Torvalds * links pointing to it. 24241da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24251da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24261da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24271da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24281da177e4SLinus Torvalds * nfs_async_unlink(). 24291da177e4SLinus Torvalds */ 2430858119e1SArjan van de Ven static int may_delete(struct inode *dir,struct dentry *victim,int isdir) 24311da177e4SLinus Torvalds { 24321da177e4SLinus Torvalds int error; 24331da177e4SLinus Torvalds 24341da177e4SLinus Torvalds if (!victim->d_inode) 24351da177e4SLinus Torvalds return -ENOENT; 24361da177e4SLinus Torvalds 24371da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24384fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24391da177e4SLinus Torvalds 2440f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24411da177e4SLinus Torvalds if (error) 24421da177e4SLinus Torvalds return error; 24431da177e4SLinus Torvalds if (IS_APPEND(dir)) 24441da177e4SLinus Torvalds return -EPERM; 24451da177e4SLinus Torvalds if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| 2446f9454548SHugh Dickins IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) 24471da177e4SLinus Torvalds return -EPERM; 24481da177e4SLinus Torvalds if (isdir) { 24491da177e4SLinus Torvalds if (!S_ISDIR(victim->d_inode->i_mode)) 24501da177e4SLinus Torvalds return -ENOTDIR; 24511da177e4SLinus Torvalds if (IS_ROOT(victim)) 24521da177e4SLinus Torvalds return -EBUSY; 24531da177e4SLinus Torvalds } else if (S_ISDIR(victim->d_inode->i_mode)) 24541da177e4SLinus Torvalds return -EISDIR; 24551da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24561da177e4SLinus Torvalds return -ENOENT; 24571da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24581da177e4SLinus Torvalds return -EBUSY; 24591da177e4SLinus Torvalds return 0; 24601da177e4SLinus Torvalds } 24611da177e4SLinus Torvalds 24621da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24631da177e4SLinus Torvalds * dir. 24641da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24651da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24661da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24671da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24681da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24691da177e4SLinus Torvalds */ 2470a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24711da177e4SLinus Torvalds { 24721da177e4SLinus Torvalds if (child->d_inode) 24731da177e4SLinus Torvalds return -EEXIST; 24741da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24751da177e4SLinus Torvalds return -ENOENT; 2476f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24771da177e4SLinus Torvalds } 24781da177e4SLinus Torvalds 24791da177e4SLinus Torvalds /* 24801da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24811da177e4SLinus Torvalds */ 24821da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24831da177e4SLinus Torvalds { 24841da177e4SLinus Torvalds struct dentry *p; 24851da177e4SLinus Torvalds 24861da177e4SLinus Torvalds if (p1 == p2) { 2487f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 24881da177e4SLinus Torvalds return NULL; 24891da177e4SLinus Torvalds } 24901da177e4SLinus Torvalds 2491a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 24921da177e4SLinus Torvalds 2493e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2494e2761a11SOGAWA Hirofumi if (p) { 2495f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2496f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 24971da177e4SLinus Torvalds return p; 24981da177e4SLinus Torvalds } 24991da177e4SLinus Torvalds 2500e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2501e2761a11SOGAWA Hirofumi if (p) { 2502f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2503f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25041da177e4SLinus Torvalds return p; 25051da177e4SLinus Torvalds } 25061da177e4SLinus Torvalds 2507f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2508f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25091da177e4SLinus Torvalds return NULL; 25101da177e4SLinus Torvalds } 25111da177e4SLinus Torvalds 25121da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25131da177e4SLinus Torvalds { 25141b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25151da177e4SLinus Torvalds if (p1 != p2) { 25161b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2517a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25181da177e4SLinus Torvalds } 25191da177e4SLinus Torvalds } 25201da177e4SLinus Torvalds 25214acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2522312b63fbSAl Viro bool want_excl) 25231da177e4SLinus Torvalds { 2524a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25251da177e4SLinus Torvalds if (error) 25261da177e4SLinus Torvalds return error; 25271da177e4SLinus Torvalds 2528acfa4380SAl Viro if (!dir->i_op->create) 25291da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25301da177e4SLinus Torvalds mode &= S_IALLUGO; 25311da177e4SLinus Torvalds mode |= S_IFREG; 25321da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25331da177e4SLinus Torvalds if (error) 25341da177e4SLinus Torvalds return error; 2535312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2536a74574aaSStephen Smalley if (!error) 2537f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25381da177e4SLinus Torvalds return error; 25391da177e4SLinus Torvalds } 25401da177e4SLinus Torvalds 254173d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25421da177e4SLinus Torvalds { 25433fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25441da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25451da177e4SLinus Torvalds int error; 25461da177e4SLinus Torvalds 2547bcda7652SAl Viro /* O_PATH? */ 2548bcda7652SAl Viro if (!acc_mode) 2549bcda7652SAl Viro return 0; 2550bcda7652SAl Viro 25511da177e4SLinus Torvalds if (!inode) 25521da177e4SLinus Torvalds return -ENOENT; 25531da177e4SLinus Torvalds 2554c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2555c8fe8f30SChristoph Hellwig case S_IFLNK: 25561da177e4SLinus Torvalds return -ELOOP; 2557c8fe8f30SChristoph Hellwig case S_IFDIR: 2558c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25591da177e4SLinus Torvalds return -EISDIR; 2560c8fe8f30SChristoph Hellwig break; 2561c8fe8f30SChristoph Hellwig case S_IFBLK: 2562c8fe8f30SChristoph Hellwig case S_IFCHR: 25633fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25641da177e4SLinus Torvalds return -EACCES; 2565c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2566c8fe8f30SChristoph Hellwig case S_IFIFO: 2567c8fe8f30SChristoph Hellwig case S_IFSOCK: 25681da177e4SLinus Torvalds flag &= ~O_TRUNC; 2569c8fe8f30SChristoph Hellwig break; 25704a3fd211SDave Hansen } 2571b41572e9SDave Hansen 25723fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2573b41572e9SDave Hansen if (error) 2574b41572e9SDave Hansen return error; 25756146f0d5SMimi Zohar 25761da177e4SLinus Torvalds /* 25771da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25781da177e4SLinus Torvalds */ 25791da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25808737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 25817715b521SAl Viro return -EPERM; 25821da177e4SLinus Torvalds if (flag & O_TRUNC) 25837715b521SAl Viro return -EPERM; 25841da177e4SLinus Torvalds } 25851da177e4SLinus Torvalds 25861da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 25872e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 25887715b521SAl Viro return -EPERM; 25891da177e4SLinus Torvalds 2590f3c7691eSJ. Bruce Fields return 0; 25917715b521SAl Viro } 25927715b521SAl Viro 2593e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 25947715b521SAl Viro { 2595e1181ee6SJeff Layton struct path *path = &filp->f_path; 25967715b521SAl Viro struct inode *inode = path->dentry->d_inode; 25977715b521SAl Viro int error = get_write_access(inode); 25981da177e4SLinus Torvalds if (error) 25997715b521SAl Viro return error; 26001da177e4SLinus Torvalds /* 26011da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26021da177e4SLinus Torvalds */ 26031da177e4SLinus Torvalds error = locks_verify_locked(inode); 2604be6d3e56SKentaro Takeda if (!error) 2605ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26061da177e4SLinus Torvalds if (!error) { 26077715b521SAl Viro error = do_truncate(path->dentry, 0, 2608d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2609e1181ee6SJeff Layton filp); 26101da177e4SLinus Torvalds } 26111da177e4SLinus Torvalds put_write_access(inode); 2612acd0c935SMimi Zohar return error; 26131da177e4SLinus Torvalds } 26141da177e4SLinus Torvalds 2615d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2616d57999e1SDave Hansen { 26178a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26188a5e929dSAl Viro flag--; 2619d57999e1SDave Hansen return flag; 2620d57999e1SDave Hansen } 2621d57999e1SDave Hansen 2622d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2623d18e9008SMiklos Szeredi { 2624d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2625d18e9008SMiklos Szeredi if (error) 2626d18e9008SMiklos Szeredi return error; 2627d18e9008SMiklos Szeredi 2628d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2629d18e9008SMiklos Szeredi if (error) 2630d18e9008SMiklos Szeredi return error; 2631d18e9008SMiklos Szeredi 2632d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2633d18e9008SMiklos Szeredi } 2634d18e9008SMiklos Szeredi 26351acf0af9SDavid Howells /* 26361acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26371acf0af9SDavid Howells * dentry. 26381acf0af9SDavid Howells * 26391acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26401acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26411acf0af9SDavid Howells * 26421acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26431acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26441acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26451acf0af9SDavid Howells * 26461acf0af9SDavid Howells * Returns an error code otherwise. 26471acf0af9SDavid Howells */ 26482675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 264930d90494SAl Viro struct path *path, struct file *file, 2650015c3bbcSMiklos Szeredi const struct open_flags *op, 265164894cf8SAl Viro bool got_write, bool need_lookup, 265247237687SAl Viro int *opened) 2653d18e9008SMiklos Szeredi { 2654d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2655d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2656d18e9008SMiklos Szeredi umode_t mode; 2657d18e9008SMiklos Szeredi int error; 2658d18e9008SMiklos Szeredi int acc_mode; 2659d18e9008SMiklos Szeredi int create_error = 0; 2660d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2661116cc022SMiklos Szeredi bool excl; 2662d18e9008SMiklos Szeredi 2663d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2664d18e9008SMiklos Szeredi 2665d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2666d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26672675a4ebSAl Viro error = -ENOENT; 2668d18e9008SMiklos Szeredi goto out; 2669d18e9008SMiklos Szeredi } 2670d18e9008SMiklos Szeredi 267162b259d8SMiklos Szeredi mode = op->mode; 2672d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2673d18e9008SMiklos Szeredi mode &= ~current_umask(); 2674d18e9008SMiklos Szeredi 2675116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2676116cc022SMiklos Szeredi if (excl) 2677d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2678d18e9008SMiklos Szeredi 2679d18e9008SMiklos Szeredi /* 2680d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2681d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2682d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2683d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2684d18e9008SMiklos Szeredi * 2685d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2686d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2687d18e9008SMiklos Szeredi */ 268864894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 268964894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 269064894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2691d18e9008SMiklos Szeredi /* 2692d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2693d18e9008SMiklos Szeredi * back to lookup + open 2694d18e9008SMiklos Szeredi */ 2695d18e9008SMiklos Szeredi goto no_open; 2696d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2697d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 269864894cf8SAl Viro create_error = -EROFS; 2699d18e9008SMiklos Szeredi goto no_open; 2700d18e9008SMiklos Szeredi } else { 2701d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 270264894cf8SAl Viro create_error = -EROFS; 2703d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2704d18e9008SMiklos Szeredi } 2705d18e9008SMiklos Szeredi } 2706d18e9008SMiklos Szeredi 2707d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 270838227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2709d18e9008SMiklos Szeredi if (error) { 2710d18e9008SMiklos Szeredi create_error = error; 2711d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2712d18e9008SMiklos Szeredi goto no_open; 2713d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2714d18e9008SMiklos Szeredi } 2715d18e9008SMiklos Szeredi } 2716d18e9008SMiklos Szeredi 2717d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2718d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2719d18e9008SMiklos Szeredi 272030d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 272130d90494SAl Viro file->f_path.mnt = nd->path.mnt; 272230d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 272347237687SAl Viro opened); 2724d9585277SAl Viro if (error < 0) { 2725d9585277SAl Viro if (create_error && error == -ENOENT) 2726d9585277SAl Viro error = create_error; 2727d18e9008SMiklos Szeredi goto out; 2728d18e9008SMiklos Szeredi } 2729d18e9008SMiklos Szeredi 2730d9585277SAl Viro if (error) { /* returned 1, that is */ 273130d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27322675a4ebSAl Viro error = -EIO; 2733d18e9008SMiklos Szeredi goto out; 2734d18e9008SMiklos Szeredi } 273530d90494SAl Viro if (file->f_path.dentry) { 2736d18e9008SMiklos Szeredi dput(dentry); 273730d90494SAl Viro dentry = file->f_path.dentry; 2738d18e9008SMiklos Szeredi } 273903da633aSAl Viro if (*opened & FILE_CREATED) 274003da633aSAl Viro fsnotify_create(dir, dentry); 274103da633aSAl Viro if (!dentry->d_inode) { 274203da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 274303da633aSAl Viro if (create_error) { 274462b2ce96SSage Weil error = create_error; 274562b2ce96SSage Weil goto out; 274662b2ce96SSage Weil } 274703da633aSAl Viro } else { 274803da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 274903da633aSAl Viro error = -EEXIST; 275003da633aSAl Viro goto out; 275103da633aSAl Viro } 275203da633aSAl Viro } 2753d18e9008SMiklos Szeredi goto looked_up; 2754d18e9008SMiklos Szeredi } 2755d18e9008SMiklos Szeredi 2756d18e9008SMiklos Szeredi /* 2757d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2758d18e9008SMiklos Szeredi * here. 2759d18e9008SMiklos Szeredi */ 276003da633aSAl Viro acc_mode = op->acc_mode; 276103da633aSAl Viro if (*opened & FILE_CREATED) { 276203da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 276303da633aSAl Viro fsnotify_create(dir, dentry); 276403da633aSAl Viro acc_mode = MAY_OPEN; 276503da633aSAl Viro } 27662675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27672675a4ebSAl Viro if (error) 27682675a4ebSAl Viro fput(file); 2769d18e9008SMiklos Szeredi 2770d18e9008SMiklos Szeredi out: 2771d18e9008SMiklos Szeredi dput(dentry); 27722675a4ebSAl Viro return error; 2773d18e9008SMiklos Szeredi 2774d18e9008SMiklos Szeredi no_open: 2775d18e9008SMiklos Szeredi if (need_lookup) { 277672bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2777d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27782675a4ebSAl Viro return PTR_ERR(dentry); 2779d18e9008SMiklos Szeredi 2780d18e9008SMiklos Szeredi if (create_error) { 2781d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2782d18e9008SMiklos Szeredi 27832675a4ebSAl Viro error = create_error; 2784d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2785d18e9008SMiklos Szeredi if (!dentry->d_inode) 2786d18e9008SMiklos Szeredi goto out; 2787d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2788d18e9008SMiklos Szeredi goto out; 2789d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2790d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2791d18e9008SMiklos Szeredi goto out; 2792d18e9008SMiklos Szeredi } 2793d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2794d18e9008SMiklos Szeredi } 2795d18e9008SMiklos Szeredi } 2796d18e9008SMiklos Szeredi looked_up: 2797d18e9008SMiklos Szeredi path->dentry = dentry; 2798d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 27992675a4ebSAl Viro return 1; 2800d18e9008SMiklos Szeredi } 2801d18e9008SMiklos Szeredi 280231e6b01fSNick Piggin /* 28031acf0af9SDavid Howells * Look up and maybe create and open the last component. 2804d58ffd35SMiklos Szeredi * 2805d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2806d58ffd35SMiklos Szeredi * 28071acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28081acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28091acf0af9SDavid Howells * 28101acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28111acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28121acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28131acf0af9SDavid Howells * specified then a negative dentry may be returned. 28141acf0af9SDavid Howells * 28151acf0af9SDavid Howells * An error code is returned otherwise. 28161acf0af9SDavid Howells * 28171acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28181acf0af9SDavid Howells * cleared otherwise prior to returning. 2819d58ffd35SMiklos Szeredi */ 28202675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 282130d90494SAl Viro struct file *file, 2822d58ffd35SMiklos Szeredi const struct open_flags *op, 282364894cf8SAl Viro bool got_write, int *opened) 2824d58ffd35SMiklos Szeredi { 2825d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 282654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2827d58ffd35SMiklos Szeredi struct dentry *dentry; 2828d58ffd35SMiklos Szeredi int error; 282954ef4872SMiklos Szeredi bool need_lookup; 2830d58ffd35SMiklos Szeredi 283147237687SAl Viro *opened &= ~FILE_CREATED; 2832201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2833d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28342675a4ebSAl Viro return PTR_ERR(dentry); 2835d58ffd35SMiklos Szeredi 2836d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2837d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2838d18e9008SMiklos Szeredi goto out_no_open; 2839d18e9008SMiklos Szeredi 2840d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 284164894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 284247237687SAl Viro need_lookup, opened); 2843d18e9008SMiklos Szeredi } 2844d18e9008SMiklos Szeredi 284554ef4872SMiklos Szeredi if (need_lookup) { 284654ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 284754ef4872SMiklos Szeredi 284872bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 284954ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28502675a4ebSAl Viro return PTR_ERR(dentry); 285154ef4872SMiklos Szeredi } 285254ef4872SMiklos Szeredi 2853d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2854d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2855d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2856d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2857d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2858d58ffd35SMiklos Szeredi /* 2859d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2860d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2861d58ffd35SMiklos Szeredi * the time when the file is created and when 2862d58ffd35SMiklos Szeredi * a permanent write count is taken through 2863015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2864d58ffd35SMiklos Szeredi */ 286564894cf8SAl Viro if (!got_write) { 286664894cf8SAl Viro error = -EROFS; 2867d58ffd35SMiklos Szeredi goto out_dput; 286864894cf8SAl Viro } 286947237687SAl Viro *opened |= FILE_CREATED; 2870d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2871d58ffd35SMiklos Szeredi if (error) 2872d58ffd35SMiklos Szeredi goto out_dput; 2873312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2874312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2875d58ffd35SMiklos Szeredi if (error) 2876d58ffd35SMiklos Szeredi goto out_dput; 2877d58ffd35SMiklos Szeredi } 2878d18e9008SMiklos Szeredi out_no_open: 2879d58ffd35SMiklos Szeredi path->dentry = dentry; 2880d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 28812675a4ebSAl Viro return 1; 2882d58ffd35SMiklos Szeredi 2883d58ffd35SMiklos Szeredi out_dput: 2884d58ffd35SMiklos Szeredi dput(dentry); 28852675a4ebSAl Viro return error; 2886d58ffd35SMiklos Szeredi } 2887d58ffd35SMiklos Szeredi 2888d58ffd35SMiklos Szeredi /* 2889fe2d35ffSAl Viro * Handle the last step of open() 289031e6b01fSNick Piggin */ 28912675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 289230d90494SAl Viro struct file *file, const struct open_flags *op, 2893669abf4eSJeff Layton int *opened, struct filename *name) 2894fb1cc555SAl Viro { 2895a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2896ca344a89SAl Viro int open_flag = op->open_flag; 289777d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 289864894cf8SAl Viro bool got_write = false; 2899bcda7652SAl Viro int acc_mode = op->acc_mode; 2900a1eb3315SMiklos Szeredi struct inode *inode; 290177d660a8SMiklos Szeredi bool symlink_ok = false; 290216b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 290316b1c1cdSMiklos Szeredi bool retried = false; 290416c2cd71SAl Viro int error; 2905fb1cc555SAl Viro 2906c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2907c3e380b0SAl Viro nd->flags |= op->intent; 2908c3e380b0SAl Viro 2909bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2910fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2911fe2d35ffSAl Viro if (error) 29122675a4ebSAl Viro return error; 2913e83db167SMiklos Szeredi goto finish_open; 29141f36f774SAl Viro } 2915a2c36b45SAl Viro 2916ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2917fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2918fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2919bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 292077d660a8SMiklos Szeredi symlink_ok = true; 2921fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2922e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 292371574865SMiklos Szeredi if (likely(!error)) 292471574865SMiklos Szeredi goto finish_lookup; 292571574865SMiklos Szeredi 2926ce57dfc1SAl Viro if (error < 0) 29272675a4ebSAl Viro goto out; 2928a1eb3315SMiklos Szeredi 292937d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2930b6183df7SMiklos Szeredi } else { 2931fe2d35ffSAl Viro /* create side of things */ 2932a3fbbde7SAl Viro /* 2933b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2934b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2935b6183df7SMiklos Szeredi * about to look up 2936a3fbbde7SAl Viro */ 29379f1fafeeSAl Viro error = complete_walk(nd); 29389f1fafeeSAl Viro if (error) 29392675a4ebSAl Viro return error; 2940fe2d35ffSAl Viro 294133e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 294216c2cd71SAl Viro error = -EISDIR; 29431f36f774SAl Viro /* trailing slashes? */ 294431e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29452675a4ebSAl Viro goto out; 2946b6183df7SMiklos Szeredi } 29471f36f774SAl Viro 294816b1c1cdSMiklos Szeredi retry_lookup: 294964894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 295064894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 295164894cf8SAl Viro if (!error) 295264894cf8SAl Viro got_write = true; 295364894cf8SAl Viro /* 295464894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 295564894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 295664894cf8SAl Viro * dropping this one anyway. 295764894cf8SAl Viro */ 295864894cf8SAl Viro } 2959a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 296064894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2961fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2962fb1cc555SAl Viro 29632675a4ebSAl Viro if (error <= 0) { 29642675a4ebSAl Viro if (error) 2965d58ffd35SMiklos Szeredi goto out; 29666c0d46c4SAl Viro 296747237687SAl Viro if ((*opened & FILE_CREATED) || 2968496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 296977d660a8SMiklos Szeredi will_truncate = false; 2970d18e9008SMiklos Szeredi 2971adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2972d18e9008SMiklos Szeredi goto opened; 2973d18e9008SMiklos Szeredi } 2974d18e9008SMiklos Szeredi 297547237687SAl Viro if (*opened & FILE_CREATED) { 29769b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2977ca344a89SAl Viro open_flag &= ~O_TRUNC; 297877d660a8SMiklos Szeredi will_truncate = false; 2979bcda7652SAl Viro acc_mode = MAY_OPEN; 2980d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2981e83db167SMiklos Szeredi goto finish_open_created; 2982fb1cc555SAl Viro } 2983fb1cc555SAl Viro 2984fb1cc555SAl Viro /* 29853134f37eSJeff Layton * create/update audit record if it already exists. 2986fb1cc555SAl Viro */ 29873134f37eSJeff Layton if (path->dentry->d_inode) 2988adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 2989fb1cc555SAl Viro 2990d18e9008SMiklos Szeredi /* 2991d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 2992d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 2993d18e9008SMiklos Szeredi * necessary...) 2994d18e9008SMiklos Szeredi */ 299564894cf8SAl Viro if (got_write) { 2996d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 299764894cf8SAl Viro got_write = false; 2998d18e9008SMiklos Szeredi } 2999d18e9008SMiklos Szeredi 3000fb1cc555SAl Viro error = -EEXIST; 3001f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3002fb1cc555SAl Viro goto exit_dput; 3003fb1cc555SAl Viro 30049875cf80SDavid Howells error = follow_managed(path, nd->flags); 30059875cf80SDavid Howells if (error < 0) 3006fb1cc555SAl Viro goto exit_dput; 3007fb1cc555SAl Viro 3008a3fbbde7SAl Viro if (error) 3009a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3010a3fbbde7SAl Viro 3011decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3012decf3400SMiklos Szeredi inode = path->dentry->d_inode; 30135f5daac1SMiklos Szeredi finish_lookup: 30145f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 3015fb1cc555SAl Viro error = -ENOENT; 301654c33e7fSMiklos Szeredi if (!inode) { 301754c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 30182675a4ebSAl Viro goto out; 301954c33e7fSMiklos Szeredi } 30209e67f361SAl Viro 3021d45ea867SMiklos Szeredi if (should_follow_link(inode, !symlink_ok)) { 3022d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3023d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 3024d45ea867SMiklos Szeredi error = -ECHILD; 30252675a4ebSAl Viro goto out; 3026d45ea867SMiklos Szeredi } 3027d45ea867SMiklos Szeredi } 3028d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 30292675a4ebSAl Viro return 1; 3030d45ea867SMiklos Szeredi } 3031fb1cc555SAl Viro 303216b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 3033fb1cc555SAl Viro path_to_nameidata(path, nd); 303416b1c1cdSMiklos Szeredi } else { 303516b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 303616b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 303716b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 303816b1c1cdSMiklos Szeredi 303916b1c1cdSMiklos Szeredi } 3040decf3400SMiklos Szeredi nd->inode = inode; 3041a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3042bc77daa7SAl Viro finish_open: 3043a3fbbde7SAl Viro error = complete_walk(nd); 304416b1c1cdSMiklos Szeredi if (error) { 304516b1c1cdSMiklos Szeredi path_put(&save_parent); 30462675a4ebSAl Viro return error; 304716b1c1cdSMiklos Szeredi } 3048bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3049fb1cc555SAl Viro error = -EISDIR; 3050050ac841SMiklos Szeredi if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) 30512675a4ebSAl Viro goto out; 3052af2f5542SMiklos Szeredi error = -ENOTDIR; 305305252901SAl Viro if ((nd->flags & LOOKUP_DIRECTORY) && !can_lookup(nd->inode)) 30542675a4ebSAl Viro goto out; 30556c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 305677d660a8SMiklos Szeredi will_truncate = false; 30576c0d46c4SAl Viro 30580f9d1a10SAl Viro if (will_truncate) { 30590f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30600f9d1a10SAl Viro if (error) 30612675a4ebSAl Viro goto out; 306264894cf8SAl Viro got_write = true; 30630f9d1a10SAl Viro } 3064e83db167SMiklos Szeredi finish_open_created: 3065bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3066ca344a89SAl Viro if (error) 30672675a4ebSAl Viro goto out; 306830d90494SAl Viro file->f_path.mnt = nd->path.mnt; 306930d90494SAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 307030d90494SAl Viro if (error) { 307130d90494SAl Viro if (error == -EOPENSTALE) 3072f60dc3dbSMiklos Szeredi goto stale_open; 3073015c3bbcSMiklos Szeredi goto out; 3074f60dc3dbSMiklos Szeredi } 3075a8277b9bSMiklos Szeredi opened: 30762675a4ebSAl Viro error = open_check_o_direct(file); 3077015c3bbcSMiklos Szeredi if (error) 3078015c3bbcSMiklos Szeredi goto exit_fput; 30792675a4ebSAl Viro error = ima_file_check(file, op->acc_mode); 3080aa4caadbSMiklos Szeredi if (error) 3081aa4caadbSMiklos Szeredi goto exit_fput; 3082aa4caadbSMiklos Szeredi 30830f9d1a10SAl Viro if (will_truncate) { 30842675a4ebSAl Viro error = handle_truncate(file); 3085aa4caadbSMiklos Szeredi if (error) 3086aa4caadbSMiklos Szeredi goto exit_fput; 30870f9d1a10SAl Viro } 3088ca344a89SAl Viro out: 308964894cf8SAl Viro if (got_write) 30900f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 309116b1c1cdSMiklos Szeredi path_put(&save_parent); 3092e276ae67SMiklos Szeredi terminate_walk(nd); 30932675a4ebSAl Viro return error; 3094fb1cc555SAl Viro 3095fb1cc555SAl Viro exit_dput: 3096fb1cc555SAl Viro path_put_conditional(path, nd); 3097ca344a89SAl Viro goto out; 3098015c3bbcSMiklos Szeredi exit_fput: 30992675a4ebSAl Viro fput(file); 31002675a4ebSAl Viro goto out; 3101015c3bbcSMiklos Szeredi 3102f60dc3dbSMiklos Szeredi stale_open: 3103f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3104f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3105f60dc3dbSMiklos Szeredi goto out; 3106f60dc3dbSMiklos Szeredi 3107f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3108f60dc3dbSMiklos Szeredi path_put(&nd->path); 3109f60dc3dbSMiklos Szeredi nd->path = save_parent; 3110f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3111f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3112f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 311364894cf8SAl Viro if (got_write) { 3114f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 311564894cf8SAl Viro got_write = false; 3116f60dc3dbSMiklos Szeredi } 3117f60dc3dbSMiklos Szeredi retried = true; 3118f60dc3dbSMiklos Szeredi goto retry_lookup; 3119fb1cc555SAl Viro } 3120fb1cc555SAl Viro 312160545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 312260545d0dSAl Viro struct nameidata *nd, int flags, 312360545d0dSAl Viro const struct open_flags *op, 312460545d0dSAl Viro struct file *file, int *opened) 312560545d0dSAl Viro { 312660545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 312760545d0dSAl Viro struct dentry *dentry, *child; 312860545d0dSAl Viro struct inode *dir; 312960545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 313060545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 313160545d0dSAl Viro if (unlikely(error)) 313260545d0dSAl Viro return error; 313360545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 313460545d0dSAl Viro if (unlikely(error)) 313560545d0dSAl Viro goto out; 313660545d0dSAl Viro /* we want directory to be writable */ 313760545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 313860545d0dSAl Viro if (error) 313960545d0dSAl Viro goto out2; 314060545d0dSAl Viro dentry = nd->path.dentry; 314160545d0dSAl Viro dir = dentry->d_inode; 314260545d0dSAl Viro if (!dir->i_op->tmpfile) { 314360545d0dSAl Viro error = -EOPNOTSUPP; 314460545d0dSAl Viro goto out2; 314560545d0dSAl Viro } 314660545d0dSAl Viro child = d_alloc(dentry, &name); 314760545d0dSAl Viro if (unlikely(!child)) { 314860545d0dSAl Viro error = -ENOMEM; 314960545d0dSAl Viro goto out2; 315060545d0dSAl Viro } 315160545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 315260545d0dSAl Viro nd->flags |= op->intent; 315360545d0dSAl Viro dput(nd->path.dentry); 315460545d0dSAl Viro nd->path.dentry = child; 315560545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 315660545d0dSAl Viro if (error) 315760545d0dSAl Viro goto out2; 315860545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 315960545d0dSAl Viro error = may_open(&nd->path, op->acc_mode, op->open_flag); 316060545d0dSAl Viro if (error) 316160545d0dSAl Viro goto out2; 316260545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 316360545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 316460545d0dSAl Viro if (error) 316560545d0dSAl Viro goto out2; 316660545d0dSAl Viro error = open_check_o_direct(file); 3167f4e0c30cSAl Viro if (error) { 316860545d0dSAl Viro fput(file); 3169f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3170f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3171f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3172f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3173f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3174f4e0c30cSAl Viro } 317560545d0dSAl Viro out2: 317660545d0dSAl Viro mnt_drop_write(nd->path.mnt); 317760545d0dSAl Viro out: 317860545d0dSAl Viro path_put(&nd->path); 317960545d0dSAl Viro return error; 318060545d0dSAl Viro } 318160545d0dSAl Viro 3182669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 318373d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 31841da177e4SLinus Torvalds { 3185fe2d35ffSAl Viro struct file *base = NULL; 318630d90494SAl Viro struct file *file; 31879850c056SAl Viro struct path path; 318847237687SAl Viro int opened = 0; 318913aab428SAl Viro int error; 319031e6b01fSNick Piggin 319130d90494SAl Viro file = get_empty_filp(); 31921afc99beSAl Viro if (IS_ERR(file)) 31931afc99beSAl Viro return file; 319431e6b01fSNick Piggin 319530d90494SAl Viro file->f_flags = op->open_flag; 319631e6b01fSNick Piggin 3197bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 319860545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 319960545d0dSAl Viro goto out; 320060545d0dSAl Viro } 320160545d0dSAl Viro 3202669abf4eSJeff Layton error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); 320331e6b01fSNick Piggin if (unlikely(error)) 32042675a4ebSAl Viro goto out; 320531e6b01fSNick Piggin 3206fe2d35ffSAl Viro current->total_link_count = 0; 3207669abf4eSJeff Layton error = link_path_walk(pathname->name, nd); 320831e6b01fSNick Piggin if (unlikely(error)) 32092675a4ebSAl Viro goto out; 32101da177e4SLinus Torvalds 32112675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 32122675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 32137b9337aaSNick Piggin struct path link = path; 3214def4af30SAl Viro void *cookie; 3215574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 321673d049a4SAl Viro path_put_conditional(&path, nd); 321773d049a4SAl Viro path_put(&nd->path); 32182675a4ebSAl Viro error = -ELOOP; 321940b39136SAl Viro break; 322040b39136SAl Viro } 3221800179c9SKees Cook error = may_follow_link(&link, nd); 3222800179c9SKees Cook if (unlikely(error)) 3223800179c9SKees Cook break; 322473d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 322573d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3226574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3227c3e380b0SAl Viro if (unlikely(error)) 32282675a4ebSAl Viro break; 32292675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3230574197e0SAl Viro put_link(nd, &link, cookie); 3231806b681cSAl Viro } 323210fa8e62SAl Viro out: 323373d049a4SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) 323473d049a4SAl Viro path_put(&nd->root); 3235fe2d35ffSAl Viro if (base) 3236fe2d35ffSAl Viro fput(base); 32372675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32382675a4ebSAl Viro BUG_ON(!error); 323930d90494SAl Viro put_filp(file); 3240015c3bbcSMiklos Szeredi } 32412675a4ebSAl Viro if (unlikely(error)) { 32422675a4ebSAl Viro if (error == -EOPENSTALE) { 32432675a4ebSAl Viro if (flags & LOOKUP_RCU) 32442675a4ebSAl Viro error = -ECHILD; 32452675a4ebSAl Viro else 32462675a4ebSAl Viro error = -ESTALE; 32472675a4ebSAl Viro } 32482675a4ebSAl Viro file = ERR_PTR(error); 32492675a4ebSAl Viro } 32502675a4ebSAl Viro return file; 3251de459215SKirill Korotaev } 32521da177e4SLinus Torvalds 3253669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3254f9652e10SAl Viro const struct open_flags *op) 325513aab428SAl Viro { 325673d049a4SAl Viro struct nameidata nd; 3257f9652e10SAl Viro int flags = op->lookup_flags; 325813aab428SAl Viro struct file *filp; 325913aab428SAl Viro 326073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 326113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 326273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 326313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 326473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 326513aab428SAl Viro return filp; 326613aab428SAl Viro } 326713aab428SAl Viro 326873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3269f9652e10SAl Viro const char *name, const struct open_flags *op) 327073d049a4SAl Viro { 327173d049a4SAl Viro struct nameidata nd; 327273d049a4SAl Viro struct file *file; 3273669abf4eSJeff Layton struct filename filename = { .name = name }; 3274f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 327573d049a4SAl Viro 327673d049a4SAl Viro nd.root.mnt = mnt; 327773d049a4SAl Viro nd.root.dentry = dentry; 327873d049a4SAl Viro 3279bcda7652SAl Viro if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) 328073d049a4SAl Viro return ERR_PTR(-ELOOP); 328173d049a4SAl Viro 3282669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); 328373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3284669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags); 328573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3286669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); 328773d049a4SAl Viro return file; 328873d049a4SAl Viro } 328973d049a4SAl Viro 32901ac12b4bSJeff Layton struct dentry *kern_path_create(int dfd, const char *pathname, 32911ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 32921da177e4SLinus Torvalds { 3293c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3294ed75e95dSAl Viro struct nameidata nd; 3295c30dabfeSJan Kara int err2; 32961ac12b4bSJeff Layton int error; 32971ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 32981ac12b4bSJeff Layton 32991ac12b4bSJeff Layton /* 33001ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33011ac12b4bSJeff Layton * other flags passed in are ignored! 33021ac12b4bSJeff Layton */ 33031ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33041ac12b4bSJeff Layton 33051ac12b4bSJeff Layton error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); 3306ed75e95dSAl Viro if (error) 3307ed75e95dSAl Viro return ERR_PTR(error); 33081da177e4SLinus Torvalds 3309c663e5d8SChristoph Hellwig /* 3310c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3311c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3312c663e5d8SChristoph Hellwig */ 3313ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3314ed75e95dSAl Viro goto out; 3315ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3316ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3317c663e5d8SChristoph Hellwig 3318c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3319c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3320c663e5d8SChristoph Hellwig /* 3321c663e5d8SChristoph Hellwig * Do the final lookup. 3322c663e5d8SChristoph Hellwig */ 3323ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3324ed75e95dSAl Viro dentry = lookup_hash(&nd); 33251da177e4SLinus Torvalds if (IS_ERR(dentry)) 3326a8104a9fSAl Viro goto unlock; 3327c663e5d8SChristoph Hellwig 3328a8104a9fSAl Viro error = -EEXIST; 3329e9baf6e5SAl Viro if (dentry->d_inode) 3330a8104a9fSAl Viro goto fail; 3331c663e5d8SChristoph Hellwig /* 3332c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3333c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3334c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3335c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3336c663e5d8SChristoph Hellwig */ 3337ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3338a8104a9fSAl Viro error = -ENOENT; 3339ed75e95dSAl Viro goto fail; 3340e9baf6e5SAl Viro } 3341c30dabfeSJan Kara if (unlikely(err2)) { 3342c30dabfeSJan Kara error = err2; 3343a8104a9fSAl Viro goto fail; 3344c30dabfeSJan Kara } 3345ed75e95dSAl Viro *path = nd.path; 3346e9baf6e5SAl Viro return dentry; 33471da177e4SLinus Torvalds fail: 3348a8104a9fSAl Viro dput(dentry); 3349a8104a9fSAl Viro dentry = ERR_PTR(error); 3350a8104a9fSAl Viro unlock: 3351dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3352c30dabfeSJan Kara if (!err2) 3353c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3354ed75e95dSAl Viro out: 3355dae6ad8fSAl Viro path_put(&nd.path); 3356ed75e95dSAl Viro return dentry; 3357dae6ad8fSAl Viro } 3358dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3359dae6ad8fSAl Viro 3360921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3361921a1650SAl Viro { 3362921a1650SAl Viro dput(dentry); 3363921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3364a8104a9fSAl Viro mnt_drop_write(path->mnt); 3365921a1650SAl Viro path_put(path); 3366921a1650SAl Viro } 3367921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3368921a1650SAl Viro 33691ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33701ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3371dae6ad8fSAl Viro { 337291a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3373dae6ad8fSAl Viro struct dentry *res; 3374dae6ad8fSAl Viro if (IS_ERR(tmp)) 3375dae6ad8fSAl Viro return ERR_CAST(tmp); 33761ac12b4bSJeff Layton res = kern_path_create(dfd, tmp->name, path, lookup_flags); 3377dae6ad8fSAl Viro putname(tmp); 3378dae6ad8fSAl Viro return res; 3379dae6ad8fSAl Viro } 3380dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3381dae6ad8fSAl Viro 33821a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 33831da177e4SLinus Torvalds { 3384a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 33851da177e4SLinus Torvalds 33861da177e4SLinus Torvalds if (error) 33871da177e4SLinus Torvalds return error; 33881da177e4SLinus Torvalds 3389975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 33901da177e4SLinus Torvalds return -EPERM; 33911da177e4SLinus Torvalds 3392acfa4380SAl Viro if (!dir->i_op->mknod) 33931da177e4SLinus Torvalds return -EPERM; 33941da177e4SLinus Torvalds 339508ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 339608ce5f16SSerge E. Hallyn if (error) 339708ce5f16SSerge E. Hallyn return error; 339808ce5f16SSerge E. Hallyn 33991da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34001da177e4SLinus Torvalds if (error) 34011da177e4SLinus Torvalds return error; 34021da177e4SLinus Torvalds 34031da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3404a74574aaSStephen Smalley if (!error) 3405f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34061da177e4SLinus Torvalds return error; 34071da177e4SLinus Torvalds } 34081da177e4SLinus Torvalds 3409f69aac00SAl Viro static int may_mknod(umode_t mode) 3410463c3197SDave Hansen { 3411463c3197SDave Hansen switch (mode & S_IFMT) { 3412463c3197SDave Hansen case S_IFREG: 3413463c3197SDave Hansen case S_IFCHR: 3414463c3197SDave Hansen case S_IFBLK: 3415463c3197SDave Hansen case S_IFIFO: 3416463c3197SDave Hansen case S_IFSOCK: 3417463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3418463c3197SDave Hansen return 0; 3419463c3197SDave Hansen case S_IFDIR: 3420463c3197SDave Hansen return -EPERM; 3421463c3197SDave Hansen default: 3422463c3197SDave Hansen return -EINVAL; 3423463c3197SDave Hansen } 3424463c3197SDave Hansen } 3425463c3197SDave Hansen 34268208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34272e4d0924SHeiko Carstens unsigned, dev) 34281da177e4SLinus Torvalds { 34291da177e4SLinus Torvalds struct dentry *dentry; 3430dae6ad8fSAl Viro struct path path; 3431dae6ad8fSAl Viro int error; 3432972567f1SJeff Layton unsigned int lookup_flags = 0; 34331da177e4SLinus Torvalds 34348e4bfca1SAl Viro error = may_mknod(mode); 34358e4bfca1SAl Viro if (error) 34368e4bfca1SAl Viro return error; 3437972567f1SJeff Layton retry: 3438972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3439dae6ad8fSAl Viro if (IS_ERR(dentry)) 3440dae6ad8fSAl Viro return PTR_ERR(dentry); 34412ad94ae6SAl Viro 3442dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3443ce3b0f8dSAl Viro mode &= ~current_umask(); 3444dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3445be6d3e56SKentaro Takeda if (error) 3446a8104a9fSAl Viro goto out; 34471da177e4SLinus Torvalds switch (mode & S_IFMT) { 34481da177e4SLinus Torvalds case 0: case S_IFREG: 3449312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34501da177e4SLinus Torvalds break; 34511da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3452dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34531da177e4SLinus Torvalds new_decode_dev(dev)); 34541da177e4SLinus Torvalds break; 34551da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3456dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34571da177e4SLinus Torvalds break; 34581da177e4SLinus Torvalds } 3459a8104a9fSAl Viro out: 3460921a1650SAl Viro done_path_create(&path, dentry); 3461972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3462972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3463972567f1SJeff Layton goto retry; 3464972567f1SJeff Layton } 34651da177e4SLinus Torvalds return error; 34661da177e4SLinus Torvalds } 34671da177e4SLinus Torvalds 34688208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34695590ff0dSUlrich Drepper { 34705590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34715590ff0dSUlrich Drepper } 34725590ff0dSUlrich Drepper 347318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 34741da177e4SLinus Torvalds { 3475a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34768de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34771da177e4SLinus Torvalds 34781da177e4SLinus Torvalds if (error) 34791da177e4SLinus Torvalds return error; 34801da177e4SLinus Torvalds 3481acfa4380SAl Viro if (!dir->i_op->mkdir) 34821da177e4SLinus Torvalds return -EPERM; 34831da177e4SLinus Torvalds 34841da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 34851da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 34861da177e4SLinus Torvalds if (error) 34871da177e4SLinus Torvalds return error; 34881da177e4SLinus Torvalds 34898de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 34908de52778SAl Viro return -EMLINK; 34918de52778SAl Viro 34921da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3493a74574aaSStephen Smalley if (!error) 3494f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 34951da177e4SLinus Torvalds return error; 34961da177e4SLinus Torvalds } 34971da177e4SLinus Torvalds 3498a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 34991da177e4SLinus Torvalds { 35006902d925SDave Hansen struct dentry *dentry; 3501dae6ad8fSAl Viro struct path path; 3502dae6ad8fSAl Viro int error; 3503b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35041da177e4SLinus Torvalds 3505b76d8b82SJeff Layton retry: 3506b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35076902d925SDave Hansen if (IS_ERR(dentry)) 3508dae6ad8fSAl Viro return PTR_ERR(dentry); 35096902d925SDave Hansen 3510dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3511ce3b0f8dSAl Viro mode &= ~current_umask(); 3512dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3513a8104a9fSAl Viro if (!error) 3514dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3515921a1650SAl Viro done_path_create(&path, dentry); 3516b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3517b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3518b76d8b82SJeff Layton goto retry; 3519b76d8b82SJeff Layton } 35201da177e4SLinus Torvalds return error; 35211da177e4SLinus Torvalds } 35221da177e4SLinus Torvalds 3523a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35245590ff0dSUlrich Drepper { 35255590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35265590ff0dSUlrich Drepper } 35275590ff0dSUlrich Drepper 35281da177e4SLinus Torvalds /* 3529a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3530c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3531a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3532a71905f0SSage Weil * then we drop the dentry now. 35331da177e4SLinus Torvalds * 35341da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35351da177e4SLinus Torvalds * do a 35361da177e4SLinus Torvalds * 35371da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35381da177e4SLinus Torvalds * return -EBUSY; 35391da177e4SLinus Torvalds * 35401da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35411da177e4SLinus Torvalds * that is still in use by something else.. 35421da177e4SLinus Torvalds */ 35431da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35441da177e4SLinus Torvalds { 35451da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35461da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 354798474236SWaiman Long if (dentry->d_lockref.count == 1) 35481da177e4SLinus Torvalds __d_drop(dentry); 35491da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35501da177e4SLinus Torvalds } 35511da177e4SLinus Torvalds 35521da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35531da177e4SLinus Torvalds { 35541da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35551da177e4SLinus Torvalds 35561da177e4SLinus Torvalds if (error) 35571da177e4SLinus Torvalds return error; 35581da177e4SLinus Torvalds 3559acfa4380SAl Viro if (!dir->i_op->rmdir) 35601da177e4SLinus Torvalds return -EPERM; 35611da177e4SLinus Torvalds 35621d2ef590SAl Viro dget(dentry); 35631b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3564912dbc15SSage Weil 35651da177e4SLinus Torvalds error = -EBUSY; 3566912dbc15SSage Weil if (d_mountpoint(dentry)) 3567912dbc15SSage Weil goto out; 3568912dbc15SSage Weil 35691da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3570912dbc15SSage Weil if (error) 3571912dbc15SSage Weil goto out; 3572912dbc15SSage Weil 35733cebde24SSage Weil shrink_dcache_parent(dentry); 35741da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3575912dbc15SSage Weil if (error) 3576912dbc15SSage Weil goto out; 3577912dbc15SSage Weil 35781da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3579d83c49f3SAl Viro dont_mount(dentry); 35801da177e4SLinus Torvalds 3581912dbc15SSage Weil out: 3582912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 35831d2ef590SAl Viro dput(dentry); 3584912dbc15SSage Weil if (!error) 3585912dbc15SSage Weil d_delete(dentry); 35861da177e4SLinus Torvalds return error; 35871da177e4SLinus Torvalds } 35881da177e4SLinus Torvalds 35895590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 35901da177e4SLinus Torvalds { 35911da177e4SLinus Torvalds int error = 0; 359291a27b2aSJeff Layton struct filename *name; 35931da177e4SLinus Torvalds struct dentry *dentry; 35941da177e4SLinus Torvalds struct nameidata nd; 3595c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3596c6ee9206SJeff Layton retry: 3597c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 359891a27b2aSJeff Layton if (IS_ERR(name)) 359991a27b2aSJeff Layton return PTR_ERR(name); 36001da177e4SLinus Torvalds 36011da177e4SLinus Torvalds switch(nd.last_type) { 36021da177e4SLinus Torvalds case LAST_DOTDOT: 36031da177e4SLinus Torvalds error = -ENOTEMPTY; 36041da177e4SLinus Torvalds goto exit1; 36051da177e4SLinus Torvalds case LAST_DOT: 36061da177e4SLinus Torvalds error = -EINVAL; 36071da177e4SLinus Torvalds goto exit1; 36081da177e4SLinus Torvalds case LAST_ROOT: 36091da177e4SLinus Torvalds error = -EBUSY; 36101da177e4SLinus Torvalds goto exit1; 36111da177e4SLinus Torvalds } 36120612d9fbSOGAWA Hirofumi 36130612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3614c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3615c30dabfeSJan Kara if (error) 3616c30dabfeSJan Kara goto exit1; 36170612d9fbSOGAWA Hirofumi 36184ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 361949705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36201da177e4SLinus Torvalds error = PTR_ERR(dentry); 36216902d925SDave Hansen if (IS_ERR(dentry)) 36226902d925SDave Hansen goto exit2; 3623e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3624e6bc45d6STheodore Ts'o error = -ENOENT; 3625e6bc45d6STheodore Ts'o goto exit3; 3626e6bc45d6STheodore Ts'o } 3627be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3628be6d3e56SKentaro Takeda if (error) 3629c30dabfeSJan Kara goto exit3; 36304ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 36310622753bSDave Hansen exit3: 36321da177e4SLinus Torvalds dput(dentry); 36336902d925SDave Hansen exit2: 36344ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3635c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 36361da177e4SLinus Torvalds exit1: 36371d957f9bSJan Blunck path_put(&nd.path); 36381da177e4SLinus Torvalds putname(name); 3639c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3640c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3641c6ee9206SJeff Layton goto retry; 3642c6ee9206SJeff Layton } 36431da177e4SLinus Torvalds return error; 36441da177e4SLinus Torvalds } 36451da177e4SLinus Torvalds 36463cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36475590ff0dSUlrich Drepper { 36485590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36495590ff0dSUlrich Drepper } 36505590ff0dSUlrich Drepper 36511da177e4SLinus Torvalds int vfs_unlink(struct inode *dir, struct dentry *dentry) 36521da177e4SLinus Torvalds { 36531da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 36541da177e4SLinus Torvalds 36551da177e4SLinus Torvalds if (error) 36561da177e4SLinus Torvalds return error; 36571da177e4SLinus Torvalds 3658acfa4380SAl Viro if (!dir->i_op->unlink) 36591da177e4SLinus Torvalds return -EPERM; 36601da177e4SLinus Torvalds 36611b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 36621da177e4SLinus Torvalds if (d_mountpoint(dentry)) 36631da177e4SLinus Torvalds error = -EBUSY; 36641da177e4SLinus Torvalds else { 36651da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3666bec1052eSAl Viro if (!error) { 36671da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 3668bec1052eSAl Viro if (!error) 3669d83c49f3SAl Viro dont_mount(dentry); 3670bec1052eSAl Viro } 36711da177e4SLinus Torvalds } 36721b1dcc1bSJes Sorensen mutex_unlock(&dentry->d_inode->i_mutex); 36731da177e4SLinus Torvalds 36741da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 36751da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 3676ece95912SJan Kara fsnotify_link_count(dentry->d_inode); 36771da177e4SLinus Torvalds d_delete(dentry); 36781da177e4SLinus Torvalds } 36790eeca283SRobert Love 36801da177e4SLinus Torvalds return error; 36811da177e4SLinus Torvalds } 36821da177e4SLinus Torvalds 36831da177e4SLinus Torvalds /* 36841da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 36851b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 36861da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 36871da177e4SLinus Torvalds * while waiting on the I/O. 36881da177e4SLinus Torvalds */ 36895590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 36901da177e4SLinus Torvalds { 36912ad94ae6SAl Viro int error; 369291a27b2aSJeff Layton struct filename *name; 36931da177e4SLinus Torvalds struct dentry *dentry; 36941da177e4SLinus Torvalds struct nameidata nd; 36951da177e4SLinus Torvalds struct inode *inode = NULL; 36965d18f813SJeff Layton unsigned int lookup_flags = 0; 36975d18f813SJeff Layton retry: 36985d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 369991a27b2aSJeff Layton if (IS_ERR(name)) 370091a27b2aSJeff Layton return PTR_ERR(name); 37012ad94ae6SAl Viro 37021da177e4SLinus Torvalds error = -EISDIR; 37031da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 37041da177e4SLinus Torvalds goto exit1; 37050612d9fbSOGAWA Hirofumi 37060612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3707c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3708c30dabfeSJan Kara if (error) 3709c30dabfeSJan Kara goto exit1; 37100612d9fbSOGAWA Hirofumi 37114ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 371249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 37131da177e4SLinus Torvalds error = PTR_ERR(dentry); 37141da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37151da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 371650338b88STörök Edwin if (nd.last.name[nd.last.len]) 371750338b88STörök Edwin goto slashes; 37181da177e4SLinus Torvalds inode = dentry->d_inode; 371950338b88STörök Edwin if (!inode) 3720e6bc45d6STheodore Ts'o goto slashes; 37217de9c6eeSAl Viro ihold(inode); 3722be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3723be6d3e56SKentaro Takeda if (error) 3724c30dabfeSJan Kara goto exit2; 37254ac91378SJan Blunck error = vfs_unlink(nd.path.dentry->d_inode, dentry); 37261da177e4SLinus Torvalds exit2: 37271da177e4SLinus Torvalds dput(dentry); 37281da177e4SLinus Torvalds } 37294ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 37301da177e4SLinus Torvalds if (inode) 37311da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3732c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 37331da177e4SLinus Torvalds exit1: 37341d957f9bSJan Blunck path_put(&nd.path); 37351da177e4SLinus Torvalds putname(name); 37365d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 37375d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 37385d18f813SJeff Layton inode = NULL; 37395d18f813SJeff Layton goto retry; 37405d18f813SJeff Layton } 37411da177e4SLinus Torvalds return error; 37421da177e4SLinus Torvalds 37431da177e4SLinus Torvalds slashes: 37441da177e4SLinus Torvalds error = !dentry->d_inode ? -ENOENT : 37451da177e4SLinus Torvalds S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; 37461da177e4SLinus Torvalds goto exit2; 37471da177e4SLinus Torvalds } 37481da177e4SLinus Torvalds 37492e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 37505590ff0dSUlrich Drepper { 37515590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 37525590ff0dSUlrich Drepper return -EINVAL; 37535590ff0dSUlrich Drepper 37545590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 37555590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 37565590ff0dSUlrich Drepper 37575590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 37585590ff0dSUlrich Drepper } 37595590ff0dSUlrich Drepper 37603480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 37615590ff0dSUlrich Drepper { 37625590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 37635590ff0dSUlrich Drepper } 37645590ff0dSUlrich Drepper 3765db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 37661da177e4SLinus Torvalds { 3767a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37681da177e4SLinus Torvalds 37691da177e4SLinus Torvalds if (error) 37701da177e4SLinus Torvalds return error; 37711da177e4SLinus Torvalds 3772acfa4380SAl Viro if (!dir->i_op->symlink) 37731da177e4SLinus Torvalds return -EPERM; 37741da177e4SLinus Torvalds 37751da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 37761da177e4SLinus Torvalds if (error) 37771da177e4SLinus Torvalds return error; 37781da177e4SLinus Torvalds 37791da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3780a74574aaSStephen Smalley if (!error) 3781f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37821da177e4SLinus Torvalds return error; 37831da177e4SLinus Torvalds } 37841da177e4SLinus Torvalds 37852e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 37862e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 37871da177e4SLinus Torvalds { 37882ad94ae6SAl Viro int error; 378991a27b2aSJeff Layton struct filename *from; 37906902d925SDave Hansen struct dentry *dentry; 3791dae6ad8fSAl Viro struct path path; 3792f46d3567SJeff Layton unsigned int lookup_flags = 0; 37931da177e4SLinus Torvalds 37941da177e4SLinus Torvalds from = getname(oldname); 37951da177e4SLinus Torvalds if (IS_ERR(from)) 37961da177e4SLinus Torvalds return PTR_ERR(from); 3797f46d3567SJeff Layton retry: 3798f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 37991da177e4SLinus Torvalds error = PTR_ERR(dentry); 38006902d925SDave Hansen if (IS_ERR(dentry)) 3801dae6ad8fSAl Viro goto out_putname; 38026902d925SDave Hansen 380391a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3804a8104a9fSAl Viro if (!error) 380591a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3806921a1650SAl Viro done_path_create(&path, dentry); 3807f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3808f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3809f46d3567SJeff Layton goto retry; 3810f46d3567SJeff Layton } 38116902d925SDave Hansen out_putname: 38121da177e4SLinus Torvalds putname(from); 38131da177e4SLinus Torvalds return error; 38141da177e4SLinus Torvalds } 38151da177e4SLinus Torvalds 38163480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 38175590ff0dSUlrich Drepper { 38185590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 38195590ff0dSUlrich Drepper } 38205590ff0dSUlrich Drepper 38211da177e4SLinus Torvalds int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) 38221da177e4SLinus Torvalds { 38231da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 38248de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 38251da177e4SLinus Torvalds int error; 38261da177e4SLinus Torvalds 38271da177e4SLinus Torvalds if (!inode) 38281da177e4SLinus Torvalds return -ENOENT; 38291da177e4SLinus Torvalds 3830a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 38311da177e4SLinus Torvalds if (error) 38321da177e4SLinus Torvalds return error; 38331da177e4SLinus Torvalds 38341da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 38351da177e4SLinus Torvalds return -EXDEV; 38361da177e4SLinus Torvalds 38371da177e4SLinus Torvalds /* 38381da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 38391da177e4SLinus Torvalds */ 38401da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 38411da177e4SLinus Torvalds return -EPERM; 3842acfa4380SAl Viro if (!dir->i_op->link) 38431da177e4SLinus Torvalds return -EPERM; 38447e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 38451da177e4SLinus Torvalds return -EPERM; 38461da177e4SLinus Torvalds 38471da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 38481da177e4SLinus Torvalds if (error) 38491da177e4SLinus Torvalds return error; 38501da177e4SLinus Torvalds 38517e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3852aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3853f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3854aae8a97dSAneesh Kumar K.V error = -ENOENT; 38558de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 38568de52778SAl Viro error = -EMLINK; 3857aae8a97dSAneesh Kumar K.V else 38581da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3859f4e0c30cSAl Viro 3860f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3861f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3862f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3863f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3864f4e0c30cSAl Viro } 38657e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3866e31e14ecSStephen Smalley if (!error) 38677e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 38681da177e4SLinus Torvalds return error; 38691da177e4SLinus Torvalds } 38701da177e4SLinus Torvalds 38711da177e4SLinus Torvalds /* 38721da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 38731da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 38741da177e4SLinus Torvalds * newname. --KAB 38751da177e4SLinus Torvalds * 38761da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 38771da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 38781da177e4SLinus Torvalds * and other special files. --ADM 38791da177e4SLinus Torvalds */ 38802e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 38812e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 38821da177e4SLinus Torvalds { 38831da177e4SLinus Torvalds struct dentry *new_dentry; 3884dae6ad8fSAl Viro struct path old_path, new_path; 388511a7b371SAneesh Kumar K.V int how = 0; 38861da177e4SLinus Torvalds int error; 38871da177e4SLinus Torvalds 388811a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3889c04030e1SUlrich Drepper return -EINVAL; 389011a7b371SAneesh Kumar K.V /* 3891f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3892f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3893f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 389411a7b371SAneesh Kumar K.V */ 3895f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3896f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3897f0cc6ffbSLinus Torvalds return -ENOENT; 389811a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3899f0cc6ffbSLinus Torvalds } 3900c04030e1SUlrich Drepper 390111a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 390211a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 3903442e31caSJeff Layton retry: 390411a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 39051da177e4SLinus Torvalds if (error) 39062ad94ae6SAl Viro return error; 39072ad94ae6SAl Viro 3908442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 3909442e31caSJeff Layton (how & LOOKUP_REVAL)); 39101da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 39116902d925SDave Hansen if (IS_ERR(new_dentry)) 3912dae6ad8fSAl Viro goto out; 3913dae6ad8fSAl Viro 3914dae6ad8fSAl Viro error = -EXDEV; 3915dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 3916dae6ad8fSAl Viro goto out_dput; 3917800179c9SKees Cook error = may_linkat(&old_path); 3918800179c9SKees Cook if (unlikely(error)) 3919800179c9SKees Cook goto out_dput; 3920dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 3921be6d3e56SKentaro Takeda if (error) 3922a8104a9fSAl Viro goto out_dput; 3923dae6ad8fSAl Viro error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); 392475c3f29dSDave Hansen out_dput: 3925921a1650SAl Viro done_path_create(&new_path, new_dentry); 3926442e31caSJeff Layton if (retry_estale(error, how)) { 3927442e31caSJeff Layton how |= LOOKUP_REVAL; 3928442e31caSJeff Layton goto retry; 3929442e31caSJeff Layton } 39301da177e4SLinus Torvalds out: 39312d8f3038SAl Viro path_put(&old_path); 39321da177e4SLinus Torvalds 39331da177e4SLinus Torvalds return error; 39341da177e4SLinus Torvalds } 39351da177e4SLinus Torvalds 39363480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 39375590ff0dSUlrich Drepper { 3938c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 39395590ff0dSUlrich Drepper } 39405590ff0dSUlrich Drepper 39411da177e4SLinus Torvalds /* 39421da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 39431da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 39441da177e4SLinus Torvalds * Problems: 39451da177e4SLinus Torvalds * a) we can get into loop creation. Check is done in is_subdir(). 39461da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 39471da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 3948a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 39491da177e4SLinus Torvalds * story. 39501da177e4SLinus Torvalds * c) we have to lock _three_ objects - parents and victim (if it exists). 39511b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 39521da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 39531da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 3954a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 39551da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 39561da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 39571da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 3958a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 39591da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 39601da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 39611da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 3962e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 39631b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 39641da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 3965c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 39661da177e4SLinus Torvalds * locking]. 39671da177e4SLinus Torvalds */ 396875c96f85SAdrian Bunk static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, 39691da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 39701da177e4SLinus Torvalds { 39711da177e4SLinus Torvalds int error = 0; 39729055cba7SSage Weil struct inode *target = new_dentry->d_inode; 39738de52778SAl Viro unsigned max_links = new_dir->i_sb->s_max_links; 39741da177e4SLinus Torvalds 39751da177e4SLinus Torvalds /* 39761da177e4SLinus Torvalds * If we are going to change the parent - check write permissions, 39771da177e4SLinus Torvalds * we'll need to flip '..'. 39781da177e4SLinus Torvalds */ 39791da177e4SLinus Torvalds if (new_dir != old_dir) { 3980f419a2e3SAl Viro error = inode_permission(old_dentry->d_inode, MAY_WRITE); 39811da177e4SLinus Torvalds if (error) 39821da177e4SLinus Torvalds return error; 39831da177e4SLinus Torvalds } 39841da177e4SLinus Torvalds 39851da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 39861da177e4SLinus Torvalds if (error) 39871da177e4SLinus Torvalds return error; 39881da177e4SLinus Torvalds 39891d2ef590SAl Viro dget(new_dentry); 3990d83c49f3SAl Viro if (target) 39911b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 39929055cba7SSage Weil 39931da177e4SLinus Torvalds error = -EBUSY; 39949055cba7SSage Weil if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) 39959055cba7SSage Weil goto out; 39969055cba7SSage Weil 39978de52778SAl Viro error = -EMLINK; 39988de52778SAl Viro if (max_links && !target && new_dir != old_dir && 39998de52778SAl Viro new_dir->i_nlink >= max_links) 40008de52778SAl Viro goto out; 40018de52778SAl Viro 40023cebde24SSage Weil if (target) 40033cebde24SSage Weil shrink_dcache_parent(new_dentry); 40041da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 40059055cba7SSage Weil if (error) 40069055cba7SSage Weil goto out; 40079055cba7SSage Weil 40081da177e4SLinus Torvalds if (target) { 40091da177e4SLinus Torvalds target->i_flags |= S_DEAD; 4010d83c49f3SAl Viro dont_mount(new_dentry); 4011d83c49f3SAl Viro } 40129055cba7SSage Weil out: 40139055cba7SSage Weil if (target) 40141b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 40151d2ef590SAl Viro dput(new_dentry); 4016e31e14ecSStephen Smalley if (!error) 4017349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 40181da177e4SLinus Torvalds d_move(old_dentry,new_dentry); 40191da177e4SLinus Torvalds return error; 40201da177e4SLinus Torvalds } 40211da177e4SLinus Torvalds 402275c96f85SAdrian Bunk static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, 40231da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 40241da177e4SLinus Torvalds { 402551892bbbSSage Weil struct inode *target = new_dentry->d_inode; 40261da177e4SLinus Torvalds int error; 40271da177e4SLinus Torvalds 40281da177e4SLinus Torvalds error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); 40291da177e4SLinus Torvalds if (error) 40301da177e4SLinus Torvalds return error; 40311da177e4SLinus Torvalds 40321da177e4SLinus Torvalds dget(new_dentry); 40331da177e4SLinus Torvalds if (target) 40341b1dcc1bSJes Sorensen mutex_lock(&target->i_mutex); 403551892bbbSSage Weil 40361da177e4SLinus Torvalds error = -EBUSY; 403751892bbbSSage Weil if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) 403851892bbbSSage Weil goto out; 403951892bbbSSage Weil 40401da177e4SLinus Torvalds error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); 404151892bbbSSage Weil if (error) 404251892bbbSSage Weil goto out; 404351892bbbSSage Weil 4044bec1052eSAl Viro if (target) 4045d83c49f3SAl Viro dont_mount(new_dentry); 4046349457ccSMark Fasheh if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) 40471da177e4SLinus Torvalds d_move(old_dentry, new_dentry); 404851892bbbSSage Weil out: 40491da177e4SLinus Torvalds if (target) 40501b1dcc1bSJes Sorensen mutex_unlock(&target->i_mutex); 40511da177e4SLinus Torvalds dput(new_dentry); 40521da177e4SLinus Torvalds return error; 40531da177e4SLinus Torvalds } 40541da177e4SLinus Torvalds 40551da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40561da177e4SLinus Torvalds struct inode *new_dir, struct dentry *new_dentry) 40571da177e4SLinus Torvalds { 40581da177e4SLinus Torvalds int error; 40591da177e4SLinus Torvalds int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); 406059b0df21SEric Paris const unsigned char *old_name; 40611da177e4SLinus Torvalds 40621da177e4SLinus Torvalds if (old_dentry->d_inode == new_dentry->d_inode) 40631da177e4SLinus Torvalds return 0; 40641da177e4SLinus Torvalds 40651da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 40661da177e4SLinus Torvalds if (error) 40671da177e4SLinus Torvalds return error; 40681da177e4SLinus Torvalds 40691da177e4SLinus Torvalds if (!new_dentry->d_inode) 4070a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 40711da177e4SLinus Torvalds else 40721da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 40731da177e4SLinus Torvalds if (error) 40741da177e4SLinus Torvalds return error; 40751da177e4SLinus Torvalds 4076acfa4380SAl Viro if (!old_dir->i_op->rename) 40771da177e4SLinus Torvalds return -EPERM; 40781da177e4SLinus Torvalds 40790eeca283SRobert Love old_name = fsnotify_oldname_init(old_dentry->d_name.name); 40800eeca283SRobert Love 40811da177e4SLinus Torvalds if (is_dir) 40821da177e4SLinus Torvalds error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); 40831da177e4SLinus Torvalds else 40841da177e4SLinus Torvalds error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); 4085123df294SAl Viro if (!error) 4086123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 40875a190ae6SAl Viro new_dentry->d_inode, old_dentry); 40880eeca283SRobert Love fsnotify_oldname_free(old_name); 40890eeca283SRobert Love 40901da177e4SLinus Torvalds return error; 40911da177e4SLinus Torvalds } 40921da177e4SLinus Torvalds 40932e4d0924SHeiko Carstens SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 40942e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40951da177e4SLinus Torvalds { 40961da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 40971da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 40981da177e4SLinus Torvalds struct dentry *trap; 40991da177e4SLinus Torvalds struct nameidata oldnd, newnd; 410091a27b2aSJeff Layton struct filename *from; 410191a27b2aSJeff Layton struct filename *to; 4102c6a94284SJeff Layton unsigned int lookup_flags = 0; 4103c6a94284SJeff Layton bool should_retry = false; 41042ad94ae6SAl Viro int error; 4105c6a94284SJeff Layton retry: 4106c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 410791a27b2aSJeff Layton if (IS_ERR(from)) { 410891a27b2aSJeff Layton error = PTR_ERR(from); 41091da177e4SLinus Torvalds goto exit; 411091a27b2aSJeff Layton } 41111da177e4SLinus Torvalds 4112c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 411391a27b2aSJeff Layton if (IS_ERR(to)) { 411491a27b2aSJeff Layton error = PTR_ERR(to); 41151da177e4SLinus Torvalds goto exit1; 411691a27b2aSJeff Layton } 41171da177e4SLinus Torvalds 41181da177e4SLinus Torvalds error = -EXDEV; 41194ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 41201da177e4SLinus Torvalds goto exit2; 41211da177e4SLinus Torvalds 41224ac91378SJan Blunck old_dir = oldnd.path.dentry; 41231da177e4SLinus Torvalds error = -EBUSY; 41241da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 41251da177e4SLinus Torvalds goto exit2; 41261da177e4SLinus Torvalds 41274ac91378SJan Blunck new_dir = newnd.path.dentry; 41281da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 41291da177e4SLinus Torvalds goto exit2; 41301da177e4SLinus Torvalds 4131c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4132c30dabfeSJan Kara if (error) 4133c30dabfeSJan Kara goto exit2; 4134c30dabfeSJan Kara 41350612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 41360612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 41374e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 41380612d9fbSOGAWA Hirofumi 41391da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 41401da177e4SLinus Torvalds 414149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 41421da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 41431da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 41441da177e4SLinus Torvalds goto exit3; 41451da177e4SLinus Torvalds /* source must exist */ 41461da177e4SLinus Torvalds error = -ENOENT; 41471da177e4SLinus Torvalds if (!old_dentry->d_inode) 41481da177e4SLinus Torvalds goto exit4; 41491da177e4SLinus Torvalds /* unless the source is a directory trailing slashes give -ENOTDIR */ 41501da177e4SLinus Torvalds if (!S_ISDIR(old_dentry->d_inode->i_mode)) { 41511da177e4SLinus Torvalds error = -ENOTDIR; 41521da177e4SLinus Torvalds if (oldnd.last.name[oldnd.last.len]) 41531da177e4SLinus Torvalds goto exit4; 41541da177e4SLinus Torvalds if (newnd.last.name[newnd.last.len]) 41551da177e4SLinus Torvalds goto exit4; 41561da177e4SLinus Torvalds } 41571da177e4SLinus Torvalds /* source should not be ancestor of target */ 41581da177e4SLinus Torvalds error = -EINVAL; 41591da177e4SLinus Torvalds if (old_dentry == trap) 41601da177e4SLinus Torvalds goto exit4; 416149705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 41621da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41631da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 41641da177e4SLinus Torvalds goto exit4; 41651da177e4SLinus Torvalds /* target should not be an ancestor of source */ 41661da177e4SLinus Torvalds error = -ENOTEMPTY; 41671da177e4SLinus Torvalds if (new_dentry == trap) 41681da177e4SLinus Torvalds goto exit5; 41691da177e4SLinus Torvalds 4170be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 4171be6d3e56SKentaro Takeda &newnd.path, new_dentry); 4172be6d3e56SKentaro Takeda if (error) 4173c30dabfeSJan Kara goto exit5; 41741da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 41751da177e4SLinus Torvalds new_dir->d_inode, new_dentry); 41761da177e4SLinus Torvalds exit5: 41771da177e4SLinus Torvalds dput(new_dentry); 41781da177e4SLinus Torvalds exit4: 41791da177e4SLinus Torvalds dput(old_dentry); 41801da177e4SLinus Torvalds exit3: 41811da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 4182c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 41831da177e4SLinus Torvalds exit2: 4184c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4185c6a94284SJeff Layton should_retry = true; 41861d957f9bSJan Blunck path_put(&newnd.path); 41872ad94ae6SAl Viro putname(to); 41881da177e4SLinus Torvalds exit1: 41891d957f9bSJan Blunck path_put(&oldnd.path); 41901da177e4SLinus Torvalds putname(from); 4191c6a94284SJeff Layton if (should_retry) { 4192c6a94284SJeff Layton should_retry = false; 4193c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4194c6a94284SJeff Layton goto retry; 4195c6a94284SJeff Layton } 41962ad94ae6SAl Viro exit: 41971da177e4SLinus Torvalds return error; 41981da177e4SLinus Torvalds } 41991da177e4SLinus Torvalds 4200a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 42015590ff0dSUlrich Drepper { 42025590ff0dSUlrich Drepper return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); 42035590ff0dSUlrich Drepper } 42045590ff0dSUlrich Drepper 42051da177e4SLinus Torvalds int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) 42061da177e4SLinus Torvalds { 42071da177e4SLinus Torvalds int len; 42081da177e4SLinus Torvalds 42091da177e4SLinus Torvalds len = PTR_ERR(link); 42101da177e4SLinus Torvalds if (IS_ERR(link)) 42111da177e4SLinus Torvalds goto out; 42121da177e4SLinus Torvalds 42131da177e4SLinus Torvalds len = strlen(link); 42141da177e4SLinus Torvalds if (len > (unsigned) buflen) 42151da177e4SLinus Torvalds len = buflen; 42161da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 42171da177e4SLinus Torvalds len = -EFAULT; 42181da177e4SLinus Torvalds out: 42191da177e4SLinus Torvalds return len; 42201da177e4SLinus Torvalds } 42211da177e4SLinus Torvalds 42221da177e4SLinus Torvalds /* 42231da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 42241da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 42251da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 42261da177e4SLinus Torvalds */ 42271da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 42281da177e4SLinus Torvalds { 42291da177e4SLinus Torvalds struct nameidata nd; 4230cc314eefSLinus Torvalds void *cookie; 4231694a1764SMarcin Slusarz int res; 4232cc314eefSLinus Torvalds 42331da177e4SLinus Torvalds nd.depth = 0; 4234cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4235694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4236694a1764SMarcin Slusarz return PTR_ERR(cookie); 4237694a1764SMarcin Slusarz 4238694a1764SMarcin Slusarz res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); 42391da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4240cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4241694a1764SMarcin Slusarz return res; 42421da177e4SLinus Torvalds } 42431da177e4SLinus Torvalds 42441da177e4SLinus Torvalds /* get the link contents into pagecache */ 42451da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 42461da177e4SLinus Torvalds { 4247ebd09abbSDuane Griffin char *kaddr; 42481da177e4SLinus Torvalds struct page *page; 42491da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4250090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 42511da177e4SLinus Torvalds if (IS_ERR(page)) 42526fe6900eSNick Piggin return (char*)page; 42531da177e4SLinus Torvalds *ppage = page; 4254ebd09abbSDuane Griffin kaddr = kmap(page); 4255ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4256ebd09abbSDuane Griffin return kaddr; 42571da177e4SLinus Torvalds } 42581da177e4SLinus Torvalds 42591da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 42601da177e4SLinus Torvalds { 42611da177e4SLinus Torvalds struct page *page = NULL; 42621da177e4SLinus Torvalds char *s = page_getlink(dentry, &page); 42631da177e4SLinus Torvalds int res = vfs_readlink(dentry,buffer,buflen,s); 42641da177e4SLinus Torvalds if (page) { 42651da177e4SLinus Torvalds kunmap(page); 42661da177e4SLinus Torvalds page_cache_release(page); 42671da177e4SLinus Torvalds } 42681da177e4SLinus Torvalds return res; 42691da177e4SLinus Torvalds } 42701da177e4SLinus Torvalds 4271cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 42721da177e4SLinus Torvalds { 4273cc314eefSLinus Torvalds struct page *page = NULL; 42741da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4275cc314eefSLinus Torvalds return page; 42761da177e4SLinus Torvalds } 42771da177e4SLinus Torvalds 4278cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 42791da177e4SLinus Torvalds { 4280cc314eefSLinus Torvalds struct page *page = cookie; 4281cc314eefSLinus Torvalds 4282cc314eefSLinus Torvalds if (page) { 42831da177e4SLinus Torvalds kunmap(page); 42841da177e4SLinus Torvalds page_cache_release(page); 42851da177e4SLinus Torvalds } 42861da177e4SLinus Torvalds } 42871da177e4SLinus Torvalds 428854566b2cSNick Piggin /* 428954566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 429054566b2cSNick Piggin */ 429154566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 42921da177e4SLinus Torvalds { 42931da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 42940adb25d2SKirill Korotaev struct page *page; 4295afddba49SNick Piggin void *fsdata; 4296beb497abSDmitriy Monakhov int err; 42971da177e4SLinus Torvalds char *kaddr; 429854566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 429954566b2cSNick Piggin if (nofs) 430054566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 43011da177e4SLinus Torvalds 43027e53cac4SNeilBrown retry: 4303afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 430454566b2cSNick Piggin flags, &page, &fsdata); 43051da177e4SLinus Torvalds if (err) 4306afddba49SNick Piggin goto fail; 4307afddba49SNick Piggin 4308e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 43091da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4310e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4311afddba49SNick Piggin 4312afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4313afddba49SNick Piggin page, fsdata); 43141da177e4SLinus Torvalds if (err < 0) 43151da177e4SLinus Torvalds goto fail; 4316afddba49SNick Piggin if (err < len-1) 4317afddba49SNick Piggin goto retry; 4318afddba49SNick Piggin 43191da177e4SLinus Torvalds mark_inode_dirty(inode); 43201da177e4SLinus Torvalds return 0; 43211da177e4SLinus Torvalds fail: 43221da177e4SLinus Torvalds return err; 43231da177e4SLinus Torvalds } 43241da177e4SLinus Torvalds 43250adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 43260adb25d2SKirill Korotaev { 43270adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 432854566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 43290adb25d2SKirill Korotaev } 43300adb25d2SKirill Korotaev 433192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 43321da177e4SLinus Torvalds .readlink = generic_readlink, 43331da177e4SLinus Torvalds .follow_link = page_follow_link_light, 43341da177e4SLinus Torvalds .put_link = page_put_link, 43351da177e4SLinus Torvalds }; 43361da177e4SLinus Torvalds 43372d8f3038SAl Viro EXPORT_SYMBOL(user_path_at); 4338cc53ce53SDavid Howells EXPORT_SYMBOL(follow_down_one); 43391da177e4SLinus Torvalds EXPORT_SYMBOL(follow_down); 43401da177e4SLinus Torvalds EXPORT_SYMBOL(follow_up); 4341f6d2ac5cSAl Viro EXPORT_SYMBOL(get_write_access); /* nfsd */ 43421da177e4SLinus Torvalds EXPORT_SYMBOL(lock_rename); 43431da177e4SLinus Torvalds EXPORT_SYMBOL(lookup_one_len); 43441da177e4SLinus Torvalds EXPORT_SYMBOL(page_follow_link_light); 43451da177e4SLinus Torvalds EXPORT_SYMBOL(page_put_link); 43461da177e4SLinus Torvalds EXPORT_SYMBOL(page_readlink); 43470adb25d2SKirill Korotaev EXPORT_SYMBOL(__page_symlink); 43481da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink); 43491da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4350d1811465SAl Viro EXPORT_SYMBOL(kern_path); 435116f18200SJosef 'Jeff' Sipek EXPORT_SYMBOL(vfs_path_lookup); 4352f419a2e3SAl Viro EXPORT_SYMBOL(inode_permission); 43531da177e4SLinus Torvalds EXPORT_SYMBOL(unlock_rename); 43541da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_create); 43551da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_link); 43561da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mkdir); 43571da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_mknod); 43581da177e4SLinus Torvalds EXPORT_SYMBOL(generic_permission); 43591da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_readlink); 43601da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rename); 43611da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_rmdir); 43621da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_symlink); 43631da177e4SLinus Torvalds EXPORT_SYMBOL(vfs_unlink); 43641da177e4SLinus Torvalds EXPORT_SYMBOL(dentry_unhash); 43651da177e4SLinus Torvalds EXPORT_SYMBOL(generic_readlink); 4366