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> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 12191a27b2aSJeff Layton void final_putname(struct filename *name) 1221da177e4SLinus Torvalds { 1237950e385SJeff Layton if (name->separate) { 12491a27b2aSJeff Layton __putname(name->name); 12591a27b2aSJeff Layton kfree(name); 1267950e385SJeff Layton } else { 1277950e385SJeff Layton __putname(name); 12891a27b2aSJeff Layton } 1297950e385SJeff Layton } 1307950e385SJeff Layton 1317950e385SJeff Layton #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) 13291a27b2aSJeff Layton 13351f39a1fSDavid Drysdale struct filename * 13491a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 13591a27b2aSJeff Layton { 13691a27b2aSJeff Layton struct filename *result, *err; 1373f9f0aa6SLinus Torvalds int len; 1387950e385SJeff Layton long max; 1397950e385SJeff Layton char *kname; 1401da177e4SLinus Torvalds 1417ac86265SJeff Layton result = audit_reusename(filename); 1427ac86265SJeff Layton if (result) 1437ac86265SJeff Layton return result; 1447ac86265SJeff Layton 1457950e385SJeff Layton result = __getname(); 1463f9f0aa6SLinus Torvalds if (unlikely(!result)) 1474043cde8SEric Paris return ERR_PTR(-ENOMEM); 1481da177e4SLinus Torvalds 1497950e385SJeff Layton /* 1507950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1517950e385SJeff Layton * allocation 1527950e385SJeff Layton */ 1537950e385SJeff Layton kname = (char *)result + sizeof(*result); 15491a27b2aSJeff Layton result->name = kname; 1557950e385SJeff Layton result->separate = false; 1567950e385SJeff Layton max = EMBEDDED_NAME_MAX; 1577950e385SJeff Layton 1587950e385SJeff Layton recopy: 1597950e385SJeff Layton len = strncpy_from_user(kname, filename, max); 16091a27b2aSJeff Layton if (unlikely(len < 0)) { 1613f9f0aa6SLinus Torvalds err = ERR_PTR(len); 1623f9f0aa6SLinus Torvalds goto error; 16391a27b2aSJeff Layton } 1643f9f0aa6SLinus Torvalds 1657950e385SJeff Layton /* 1667950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1677950e385SJeff Layton * separate struct filename so we can dedicate the entire 1687950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1697950e385SJeff Layton * userland. 1707950e385SJeff Layton */ 1717950e385SJeff Layton if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { 1727950e385SJeff Layton kname = (char *)result; 1737950e385SJeff Layton 1747950e385SJeff Layton result = kzalloc(sizeof(*result), GFP_KERNEL); 1757950e385SJeff Layton if (!result) { 1767950e385SJeff Layton err = ERR_PTR(-ENOMEM); 1777950e385SJeff Layton result = (struct filename *)kname; 1787950e385SJeff Layton goto error; 1797950e385SJeff Layton } 1807950e385SJeff Layton result->name = kname; 1817950e385SJeff Layton result->separate = true; 1827950e385SJeff Layton max = PATH_MAX; 1837950e385SJeff Layton goto recopy; 1847950e385SJeff Layton } 1857950e385SJeff Layton 1863f9f0aa6SLinus Torvalds /* The empty path is special. */ 1873f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1883f9f0aa6SLinus Torvalds if (empty) 1891fa1e7f6SAndy Whitcroft *empty = 1; 1903f9f0aa6SLinus Torvalds err = ERR_PTR(-ENOENT); 1913f9f0aa6SLinus Torvalds if (!(flags & LOOKUP_EMPTY)) 1923f9f0aa6SLinus Torvalds goto error; 1931da177e4SLinus Torvalds } 1943f9f0aa6SLinus Torvalds 1953f9f0aa6SLinus Torvalds err = ERR_PTR(-ENAMETOOLONG); 1967950e385SJeff Layton if (unlikely(len >= PATH_MAX)) 1977950e385SJeff Layton goto error; 1987950e385SJeff Layton 1997950e385SJeff Layton result->uptr = filename; 200c4ad8f98SLinus Torvalds result->aname = NULL; 2011da177e4SLinus Torvalds audit_getname(result); 2021da177e4SLinus Torvalds return result; 2031da177e4SLinus Torvalds 2043f9f0aa6SLinus Torvalds error: 2057950e385SJeff Layton final_putname(result); 2063f9f0aa6SLinus Torvalds return err; 2073f9f0aa6SLinus Torvalds } 2083f9f0aa6SLinus Torvalds 20991a27b2aSJeff Layton struct filename * 21091a27b2aSJeff Layton getname(const char __user * filename) 211f52e0c11SAl Viro { 212f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 213f52e0c11SAl Viro } 214f52e0c11SAl Viro 215c4ad8f98SLinus Torvalds struct filename * 216c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 217c4ad8f98SLinus Torvalds { 218c4ad8f98SLinus Torvalds struct filename *result; 21908518549SPaul Moore int len = strlen(filename) + 1; 220c4ad8f98SLinus Torvalds 221c4ad8f98SLinus Torvalds result = __getname(); 222c4ad8f98SLinus Torvalds if (unlikely(!result)) 223c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 224c4ad8f98SLinus Torvalds 22508518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 22608518549SPaul Moore result->name = (char *)(result) + sizeof(*result); 22708518549SPaul Moore result->separate = false; 22808518549SPaul Moore } else if (len <= PATH_MAX) { 22908518549SPaul Moore struct filename *tmp; 23008518549SPaul Moore 23108518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 23208518549SPaul Moore if (unlikely(!tmp)) { 23308518549SPaul Moore __putname(result); 23408518549SPaul Moore return ERR_PTR(-ENOMEM); 23508518549SPaul Moore } 23608518549SPaul Moore tmp->name = (char *)result; 23708518549SPaul Moore tmp->separate = true; 23808518549SPaul Moore result = tmp; 23908518549SPaul Moore } else { 24008518549SPaul Moore __putname(result); 24108518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 24208518549SPaul Moore } 24308518549SPaul Moore memcpy((char *)result->name, filename, len); 244c4ad8f98SLinus Torvalds result->uptr = NULL; 245c4ad8f98SLinus Torvalds result->aname = NULL; 246c4ad8f98SLinus Torvalds 247c4ad8f98SLinus Torvalds return result; 248c4ad8f98SLinus Torvalds } 249c4ad8f98SLinus Torvalds 2501da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 25191a27b2aSJeff Layton void putname(struct filename *name) 2521da177e4SLinus Torvalds { 2535ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 25491a27b2aSJeff Layton return audit_putname(name); 25591a27b2aSJeff Layton final_putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds #endif 2581da177e4SLinus Torvalds 259e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 260e77819e5SLinus Torvalds { 26184635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 262e77819e5SLinus Torvalds struct posix_acl *acl; 263e77819e5SLinus Torvalds 264e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2653567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2663567866bSAl Viro if (!acl) 267e77819e5SLinus Torvalds return -EAGAIN; 2683567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2693567866bSAl Viro if (acl == ACL_NOT_CACHED) 270e77819e5SLinus Torvalds return -ECHILD; 271206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 272e77819e5SLinus Torvalds } 273e77819e5SLinus Torvalds 2742982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2754e34e719SChristoph Hellwig if (IS_ERR(acl)) 2764e34e719SChristoph Hellwig return PTR_ERR(acl); 277e77819e5SLinus Torvalds if (acl) { 278e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 279e77819e5SLinus Torvalds posix_acl_release(acl); 280e77819e5SLinus Torvalds return error; 281e77819e5SLinus Torvalds } 28284635d68SLinus Torvalds #endif 283e77819e5SLinus Torvalds 284e77819e5SLinus Torvalds return -EAGAIN; 285e77819e5SLinus Torvalds } 286e77819e5SLinus Torvalds 2875909ccaaSLinus Torvalds /* 288948409c7SAndreas Gruenbacher * This does the basic permission checking 2895909ccaaSLinus Torvalds */ 2907e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2915909ccaaSLinus Torvalds { 29226cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2935909ccaaSLinus Torvalds 2948e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2955909ccaaSLinus Torvalds mode >>= 6; 2965909ccaaSLinus Torvalds else { 297e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2987e40145eSAl Viro int error = check_acl(inode, mask); 2995909ccaaSLinus Torvalds if (error != -EAGAIN) 3005909ccaaSLinus Torvalds return error; 3015909ccaaSLinus Torvalds } 3025909ccaaSLinus Torvalds 3035909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3045909ccaaSLinus Torvalds mode >>= 3; 3055909ccaaSLinus Torvalds } 3065909ccaaSLinus Torvalds 3075909ccaaSLinus Torvalds /* 3085909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3095909ccaaSLinus Torvalds */ 3109c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3115909ccaaSLinus Torvalds return 0; 3125909ccaaSLinus Torvalds return -EACCES; 3135909ccaaSLinus Torvalds } 3141da177e4SLinus Torvalds 3151da177e4SLinus Torvalds /** 3161da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3171da177e4SLinus Torvalds * @inode: inode to check access rights for 3188fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3191da177e4SLinus Torvalds * 3201da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3211da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3221da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 323b74c79e9SNick Piggin * are used for other things. 324b74c79e9SNick Piggin * 325b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 326b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 327b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3281da177e4SLinus Torvalds */ 3292830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3301da177e4SLinus Torvalds { 3315909ccaaSLinus Torvalds int ret; 3321da177e4SLinus Torvalds 3331da177e4SLinus Torvalds /* 334948409c7SAndreas Gruenbacher * Do the basic permission checks. 3351da177e4SLinus Torvalds */ 3367e40145eSAl Viro ret = acl_permission_check(inode, mask); 3375909ccaaSLinus Torvalds if (ret != -EACCES) 3385909ccaaSLinus Torvalds return ret; 3391da177e4SLinus Torvalds 340d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 341d594e7ecSAl Viro /* DACs are overridable for directories */ 34223adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 343d594e7ecSAl Viro return 0; 344d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34623adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 347d594e7ecSAl Viro return 0; 348d594e7ecSAl Viro return -EACCES; 349d594e7ecSAl Viro } 3501da177e4SLinus Torvalds /* 3511da177e4SLinus Torvalds * Read/write DACs are always overridable. 352d594e7ecSAl Viro * Executable DACs are overridable when there is 353d594e7ecSAl Viro * at least one exec bit set. 3541da177e4SLinus Torvalds */ 355d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3571da177e4SLinus Torvalds return 0; 3581da177e4SLinus Torvalds 3591da177e4SLinus Torvalds /* 3601da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3611da177e4SLinus Torvalds */ 3627ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 363d594e7ecSAl Viro if (mask == MAY_READ) 36423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3651da177e4SLinus Torvalds return 0; 3661da177e4SLinus Torvalds 3671da177e4SLinus Torvalds return -EACCES; 3681da177e4SLinus Torvalds } 3694d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3701da177e4SLinus Torvalds 3713ddcd056SLinus Torvalds /* 3723ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3733ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3743ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3753ddcd056SLinus Torvalds * permission function, use the fast case". 3763ddcd056SLinus Torvalds */ 3773ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3783ddcd056SLinus Torvalds { 3793ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3803ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3813ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3823ddcd056SLinus Torvalds 3833ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3843ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3853ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3863ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3873ddcd056SLinus Torvalds } 3883ddcd056SLinus Torvalds return generic_permission(inode, mask); 3893ddcd056SLinus Torvalds } 3903ddcd056SLinus Torvalds 391cb23beb5SChristoph Hellwig /** 3920bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3930bdaea90SDavid Howells * @inode: Inode to check permission on 3940bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 395cb23beb5SChristoph Hellwig * 3960bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 397948409c7SAndreas Gruenbacher * 398948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4010bdaea90SDavid Howells * inode_permission(). 402cb23beb5SChristoph Hellwig */ 4030bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4041da177e4SLinus Torvalds { 405e6305c43SAl Viro int retval; 4061da177e4SLinus Torvalds 4073ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4081da177e4SLinus Torvalds /* 4091da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4101da177e4SLinus Torvalds */ 4111da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4121da177e4SLinus Torvalds return -EACCES; 4131da177e4SLinus Torvalds } 4141da177e4SLinus Torvalds 4153ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4161da177e4SLinus Torvalds if (retval) 4171da177e4SLinus Torvalds return retval; 4181da177e4SLinus Torvalds 41908ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 42008ce5f16SSerge E. Hallyn if (retval) 42108ce5f16SSerge E. Hallyn return retval; 42208ce5f16SSerge E. Hallyn 423d09ca739SEric Paris return security_inode_permission(inode, mask); 4241da177e4SLinus Torvalds } 425bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4261da177e4SLinus Torvalds 427f4d6ff89SAl Viro /** 4280bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4290bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 43055852635SRandy Dunlap * @inode: Inode to check permission on 4310bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4320bdaea90SDavid Howells * 4330bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4340bdaea90SDavid Howells */ 4350bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4360bdaea90SDavid Howells { 4370bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4380bdaea90SDavid Howells umode_t mode = inode->i_mode; 4390bdaea90SDavid Howells 4400bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4410bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4420bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4430bdaea90SDavid Howells return -EROFS; 4440bdaea90SDavid Howells } 4450bdaea90SDavid Howells return 0; 4460bdaea90SDavid Howells } 4470bdaea90SDavid Howells 4480bdaea90SDavid Howells /** 4490bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4500bdaea90SDavid Howells * @inode: Inode to check permission on 4510bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4520bdaea90SDavid Howells * 4530bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4540bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4550bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4560bdaea90SDavid Howells * 4570bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4580bdaea90SDavid Howells */ 4590bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4600bdaea90SDavid Howells { 4610bdaea90SDavid Howells int retval; 4620bdaea90SDavid Howells 4630bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4640bdaea90SDavid Howells if (retval) 4650bdaea90SDavid Howells return retval; 4660bdaea90SDavid Howells return __inode_permission(inode, mask); 4670bdaea90SDavid Howells } 4684d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4690bdaea90SDavid Howells 4700bdaea90SDavid Howells /** 4715dd784d0SJan Blunck * path_get - get a reference to a path 4725dd784d0SJan Blunck * @path: path to get the reference to 4735dd784d0SJan Blunck * 4745dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4755dd784d0SJan Blunck */ 476dcf787f3SAl Viro void path_get(const struct path *path) 4775dd784d0SJan Blunck { 4785dd784d0SJan Blunck mntget(path->mnt); 4795dd784d0SJan Blunck dget(path->dentry); 4805dd784d0SJan Blunck } 4815dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4825dd784d0SJan Blunck 4835dd784d0SJan Blunck /** 4841d957f9bSJan Blunck * path_put - put a reference to a path 4851d957f9bSJan Blunck * @path: path to put the reference to 4861d957f9bSJan Blunck * 4871d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4881d957f9bSJan Blunck */ 489dcf787f3SAl Viro void path_put(const struct path *path) 4901da177e4SLinus Torvalds { 4911d957f9bSJan Blunck dput(path->dentry); 4921d957f9bSJan Blunck mntput(path->mnt); 4931da177e4SLinus Torvalds } 4941d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4951da177e4SLinus Torvalds 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 5055e53084dSAl Viro struct file *base; 5061f55a6ecSAl Viro char *saved_names[MAX_NESTED_LINKS + 1]; 5071f55a6ecSAl Viro }; 5081f55a6ecSAl Viro 50919660af7SAl Viro /* 51031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 51119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 51219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 51319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 51419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 51519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 51619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 51719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 51831e6b01fSNick Piggin */ 51931e6b01fSNick Piggin 52031e6b01fSNick Piggin /** 52119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 52219660af7SAl Viro * @nd: nameidata pathwalk data 52319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 52439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 52531e6b01fSNick Piggin * 52619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 52719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 52819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 52931e6b01fSNick Piggin */ 53019660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 53131e6b01fSNick Piggin { 53231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 53331e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 53431e6b01fSNick Piggin 53531e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 536e5c832d5SLinus Torvalds 537e5c832d5SLinus Torvalds /* 53848a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 53948a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 54048a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 54148a066e7SAl Viro * before returning. Do vfsmount first; if dentry 54248a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 54348a066e7SAl Viro * and rely on dput(NULL) being a no-op. 544e5c832d5SLinus Torvalds */ 54548a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 546e5c832d5SLinus Torvalds return -ECHILD; 547e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 54815570086SLinus Torvalds 54948a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 55048a066e7SAl Viro nd->path.dentry = NULL; 551d870b4a1SAl Viro goto out; 55248a066e7SAl Viro } 55348a066e7SAl Viro 55415570086SLinus Torvalds /* 55515570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 55615570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 55715570086SLinus Torvalds * 55815570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 55915570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 56015570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 56115570086SLinus Torvalds * since we checked the sequence number of the parent after we got 56215570086SLinus Torvalds * the child sequence number. So we know the parent must still 56315570086SLinus Torvalds * be valid if the child sequence number is still valid. 56415570086SLinus Torvalds */ 56519660af7SAl Viro if (!dentry) { 566e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 567e5c832d5SLinus Torvalds goto out; 56819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 56919660af7SAl Viro } else { 570e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 571e5c832d5SLinus Torvalds goto out; 572e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 573e5c832d5SLinus Torvalds goto drop_dentry; 57419660af7SAl Viro } 575e5c832d5SLinus Torvalds 576e5c832d5SLinus Torvalds /* 577e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 578e5c832d5SLinus Torvalds * still valid and get it if required. 579e5c832d5SLinus Torvalds */ 580e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 581e5c832d5SLinus Torvalds spin_lock(&fs->lock); 582e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 583e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 58431e6b01fSNick Piggin path_get(&nd->root); 58531e6b01fSNick Piggin spin_unlock(&fs->lock); 58631e6b01fSNick Piggin } 58731e6b01fSNick Piggin 5888b61e74fSAl Viro rcu_read_unlock(); 58931e6b01fSNick Piggin return 0; 59019660af7SAl Viro 591e5c832d5SLinus Torvalds unlock_and_drop_dentry: 59231e6b01fSNick Piggin spin_unlock(&fs->lock); 593e5c832d5SLinus Torvalds drop_dentry: 5948b61e74fSAl Viro rcu_read_unlock(); 595e5c832d5SLinus Torvalds dput(dentry); 596d0d27277SLinus Torvalds goto drop_root_mnt; 597e5c832d5SLinus Torvalds out: 5988b61e74fSAl Viro rcu_read_unlock(); 599d0d27277SLinus Torvalds drop_root_mnt: 600d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 601d0d27277SLinus Torvalds nd->root.mnt = NULL; 60231e6b01fSNick Piggin return -ECHILD; 60331e6b01fSNick Piggin } 60431e6b01fSNick Piggin 6054ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 60634286d66SNick Piggin { 6074ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 60834286d66SNick Piggin } 60934286d66SNick Piggin 6109f1fafeeSAl Viro /** 6119f1fafeeSAl Viro * complete_walk - successful completion of path walk 6129f1fafeeSAl Viro * @nd: pointer nameidata 61339159de2SJeff Layton * 6149f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6159f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6169f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6179f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6189f1fafeeSAl Viro * need to drop nd->path. 61939159de2SJeff Layton */ 6209f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 62139159de2SJeff Layton { 62216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 62339159de2SJeff Layton int status; 62439159de2SJeff Layton 6259f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6269f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6279f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6289f1fafeeSAl Viro nd->root.mnt = NULL; 62915570086SLinus Torvalds 63048a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6318b61e74fSAl Viro rcu_read_unlock(); 63248a066e7SAl Viro return -ECHILD; 63348a066e7SAl Viro } 634e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6358b61e74fSAl Viro rcu_read_unlock(); 63648a066e7SAl Viro mntput(nd->path.mnt); 6379f1fafeeSAl Viro return -ECHILD; 6389f1fafeeSAl Viro } 639e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6408b61e74fSAl Viro rcu_read_unlock(); 641e5c832d5SLinus Torvalds dput(dentry); 64248a066e7SAl Viro mntput(nd->path.mnt); 643e5c832d5SLinus Torvalds return -ECHILD; 644e5c832d5SLinus Torvalds } 6458b61e74fSAl Viro rcu_read_unlock(); 6469f1fafeeSAl Viro } 6479f1fafeeSAl Viro 64816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 64939159de2SJeff Layton return 0; 65039159de2SJeff Layton 651ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 65216c2cd71SAl Viro return 0; 65316c2cd71SAl Viro 654ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 65539159de2SJeff Layton if (status > 0) 65639159de2SJeff Layton return 0; 65739159de2SJeff Layton 65816c2cd71SAl Viro if (!status) 65939159de2SJeff Layton status = -ESTALE; 66016c2cd71SAl Viro 6619f1fafeeSAl Viro path_put(&nd->path); 66239159de2SJeff Layton return status; 66339159de2SJeff Layton } 66439159de2SJeff Layton 6652a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6662a737871SAl Viro { 667f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6682a737871SAl Viro } 6692a737871SAl Viro 6706de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6716de88d72SAl Viro 6727bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 67331e6b01fSNick Piggin { 67431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6757bd88377SAl Viro unsigned seq, res; 676c28cc364SNick Piggin 677c28cc364SNick Piggin do { 678c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 67931e6b01fSNick Piggin nd->root = fs->root; 6807bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 681c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6827bd88377SAl Viro return res; 68331e6b01fSNick Piggin } 68431e6b01fSNick Piggin 6851d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 686051d3812SIan Kent { 687051d3812SIan Kent dput(path->dentry); 6884ac91378SJan Blunck if (path->mnt != nd->path.mnt) 689051d3812SIan Kent mntput(path->mnt); 690051d3812SIan Kent } 691051d3812SIan Kent 6927b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6937b9337aaSNick Piggin struct nameidata *nd) 694051d3812SIan Kent { 69531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6964ac91378SJan Blunck dput(nd->path.dentry); 69731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6984ac91378SJan Blunck mntput(nd->path.mnt); 6999a229683SHuang Shijie } 70031e6b01fSNick Piggin nd->path.mnt = path->mnt; 7014ac91378SJan Blunck nd->path.dentry = path->dentry; 702051d3812SIan Kent } 703051d3812SIan Kent 704b5fb63c1SChristoph Hellwig /* 705b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 706b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 707b5fb63c1SChristoph Hellwig */ 708b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 709b5fb63c1SChristoph Hellwig { 710b5fb63c1SChristoph Hellwig path_put(&nd->path); 711b5fb63c1SChristoph Hellwig 712b5fb63c1SChristoph Hellwig nd->path = *path; 713b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 714b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 715b5fb63c1SChristoph Hellwig } 716b5fb63c1SChristoph Hellwig 7171f55a6ecSAl Viro void nd_set_link(struct nameidata *nd, char *path) 7181f55a6ecSAl Viro { 7191f55a6ecSAl Viro nd->saved_names[nd->depth] = path; 7201f55a6ecSAl Viro } 7211f55a6ecSAl Viro EXPORT_SYMBOL(nd_set_link); 7221f55a6ecSAl Viro 7231f55a6ecSAl Viro char *nd_get_link(struct nameidata *nd) 7241f55a6ecSAl Viro { 7251f55a6ecSAl Viro return nd->saved_names[nd->depth]; 7261f55a6ecSAl Viro } 7271f55a6ecSAl Viro EXPORT_SYMBOL(nd_get_link); 7281f55a6ecSAl Viro 729574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 730574197e0SAl Viro { 731574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 7326d7b5aaeSAl Viro if (inode->i_op->put_link) 733574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 734574197e0SAl Viro path_put(link); 735574197e0SAl Viro } 736574197e0SAl Viro 737561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 738561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 739800179c9SKees Cook 740800179c9SKees Cook /** 741800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 742800179c9SKees Cook * @link: The path of the symlink 74355852635SRandy Dunlap * @nd: nameidata pathwalk data 744800179c9SKees Cook * 745800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 746800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 747800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 748800179c9SKees Cook * processes from failing races against path names that may change out 749800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 750800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 751800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 752800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 753800179c9SKees Cook * 754800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 755800179c9SKees Cook */ 756800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 757800179c9SKees Cook { 758800179c9SKees Cook const struct inode *inode; 759800179c9SKees Cook const struct inode *parent; 760800179c9SKees Cook 761800179c9SKees Cook if (!sysctl_protected_symlinks) 762800179c9SKees Cook return 0; 763800179c9SKees Cook 764800179c9SKees Cook /* Allowed if owner and follower match. */ 765800179c9SKees Cook inode = link->dentry->d_inode; 76681abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 767800179c9SKees Cook return 0; 768800179c9SKees Cook 769800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 770800179c9SKees Cook parent = nd->path.dentry->d_inode; 771800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 772800179c9SKees Cook return 0; 773800179c9SKees Cook 774800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 77581abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 776800179c9SKees Cook return 0; 777800179c9SKees Cook 778ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 779800179c9SKees Cook path_put_conditional(link, nd); 780800179c9SKees Cook path_put(&nd->path); 781800179c9SKees Cook return -EACCES; 782800179c9SKees Cook } 783800179c9SKees Cook 784800179c9SKees Cook /** 785800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 786800179c9SKees Cook * @inode: the source inode to hardlink from 787800179c9SKees Cook * 788800179c9SKees Cook * Return false if at least one of the following conditions: 789800179c9SKees Cook * - inode is not a regular file 790800179c9SKees Cook * - inode is setuid 791800179c9SKees Cook * - inode is setgid and group-exec 792800179c9SKees Cook * - access failure for read and write 793800179c9SKees Cook * 794800179c9SKees Cook * Otherwise returns true. 795800179c9SKees Cook */ 796800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 797800179c9SKees Cook { 798800179c9SKees Cook umode_t mode = inode->i_mode; 799800179c9SKees Cook 800800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 801800179c9SKees Cook if (!S_ISREG(mode)) 802800179c9SKees Cook return false; 803800179c9SKees Cook 804800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 805800179c9SKees Cook if (mode & S_ISUID) 806800179c9SKees Cook return false; 807800179c9SKees Cook 808800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 809800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 810800179c9SKees Cook return false; 811800179c9SKees Cook 812800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 813800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 814800179c9SKees Cook return false; 815800179c9SKees Cook 816800179c9SKees Cook return true; 817800179c9SKees Cook } 818800179c9SKees Cook 819800179c9SKees Cook /** 820800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 821800179c9SKees Cook * @link: the source to hardlink from 822800179c9SKees Cook * 823800179c9SKees Cook * Block hardlink when all of: 824800179c9SKees Cook * - sysctl_protected_hardlinks enabled 825800179c9SKees Cook * - fsuid does not match inode 826800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 827800179c9SKees Cook * - not CAP_FOWNER 828800179c9SKees Cook * 829800179c9SKees Cook * Returns 0 if successful, -ve on error. 830800179c9SKees Cook */ 831800179c9SKees Cook static int may_linkat(struct path *link) 832800179c9SKees Cook { 833800179c9SKees Cook const struct cred *cred; 834800179c9SKees Cook struct inode *inode; 835800179c9SKees Cook 836800179c9SKees Cook if (!sysctl_protected_hardlinks) 837800179c9SKees Cook return 0; 838800179c9SKees Cook 839800179c9SKees Cook cred = current_cred(); 840800179c9SKees Cook inode = link->dentry->d_inode; 841800179c9SKees Cook 842800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 843800179c9SKees Cook * otherwise, it must be a safe source. 844800179c9SKees Cook */ 84581abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 846800179c9SKees Cook capable(CAP_FOWNER)) 847800179c9SKees Cook return 0; 848800179c9SKees Cook 849a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 850800179c9SKees Cook return -EPERM; 851800179c9SKees Cook } 852800179c9SKees Cook 853def4af30SAl Viro static __always_inline int 854574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 8551da177e4SLinus Torvalds { 8567b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8576d7b5aaeSAl Viro int error; 8586d7b5aaeSAl Viro char *s; 8591da177e4SLinus Torvalds 860844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 861844a3917SAl Viro 8620e794589SAl Viro if (link->mnt == nd->path.mnt) 8630e794589SAl Viro mntget(link->mnt); 8640e794589SAl Viro 8656d7b5aaeSAl Viro error = -ELOOP; 8666d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8676d7b5aaeSAl Viro goto out_put_nd_path; 8686d7b5aaeSAl Viro 869574197e0SAl Viro cond_resched(); 870574197e0SAl Viro current->total_link_count++; 871574197e0SAl Viro 87268ac1234SAl Viro touch_atime(link); 8731da177e4SLinus Torvalds nd_set_link(nd, NULL); 874cd4e91d3SAl Viro 87536f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8766d7b5aaeSAl Viro if (error) 8776d7b5aaeSAl Viro goto out_put_nd_path; 87836f3b4f6SAl Viro 87986acdca1SAl Viro nd->last_type = LAST_BIND; 880def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 881def4af30SAl Viro error = PTR_ERR(*p); 8826d7b5aaeSAl Viro if (IS_ERR(*p)) 883408ef013SChristoph Hellwig goto out_put_nd_path; 8846d7b5aaeSAl Viro 885cc314eefSLinus Torvalds error = 0; 8866d7b5aaeSAl Viro s = nd_get_link(nd); 8876d7b5aaeSAl Viro if (s) { 888443ed254SAl Viro if (unlikely(IS_ERR(s))) { 889443ed254SAl Viro path_put(&nd->path); 890443ed254SAl Viro put_link(nd, link, *p); 891443ed254SAl Viro return PTR_ERR(s); 892443ed254SAl Viro } 893443ed254SAl Viro if (*s == '/') { 8947bd88377SAl Viro if (!nd->root.mnt) 895443ed254SAl Viro set_root(nd); 896443ed254SAl Viro path_put(&nd->path); 897443ed254SAl Viro nd->path = nd->root; 898443ed254SAl Viro path_get(&nd->root); 899443ed254SAl Viro nd->flags |= LOOKUP_JUMPED; 900443ed254SAl Viro } 901443ed254SAl Viro nd->inode = nd->path.dentry->d_inode; 902443ed254SAl Viro error = link_path_walk(s, nd); 9036d7b5aaeSAl Viro if (unlikely(error)) 9046d7b5aaeSAl Viro put_link(nd, link, *p); 905b5fb63c1SChristoph Hellwig } 9066d7b5aaeSAl Viro 9076d7b5aaeSAl Viro return error; 9086d7b5aaeSAl Viro 9096d7b5aaeSAl Viro out_put_nd_path: 91098f6ef64SArnd Bergmann *p = NULL; 9116d7b5aaeSAl Viro path_put(&nd->path); 9126d7b5aaeSAl Viro path_put(link); 9131da177e4SLinus Torvalds return error; 9141da177e4SLinus Torvalds } 9151da177e4SLinus Torvalds 91631e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 91731e6b01fSNick Piggin { 9180714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9190714a533SAl Viro struct mount *parent; 92031e6b01fSNick Piggin struct dentry *mountpoint; 92131e6b01fSNick Piggin 9220714a533SAl Viro parent = mnt->mnt_parent; 9230714a533SAl Viro if (&parent->mnt == path->mnt) 92431e6b01fSNick Piggin return 0; 925a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 92631e6b01fSNick Piggin path->dentry = mountpoint; 9270714a533SAl Viro path->mnt = &parent->mnt; 92831e6b01fSNick Piggin return 1; 92931e6b01fSNick Piggin } 93031e6b01fSNick Piggin 931f015f126SDavid Howells /* 932f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 933f015f126SDavid Howells * 934f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 935f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 936f015f126SDavid Howells * Up is towards /. 937f015f126SDavid Howells * 938f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 939f015f126SDavid Howells * root. 940f015f126SDavid Howells */ 941bab77ebfSAl Viro int follow_up(struct path *path) 9421da177e4SLinus Torvalds { 9430714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9440714a533SAl Viro struct mount *parent; 9451da177e4SLinus Torvalds struct dentry *mountpoint; 94699b7db7bSNick Piggin 94748a066e7SAl Viro read_seqlock_excl(&mount_lock); 9480714a533SAl Viro parent = mnt->mnt_parent; 9493c0a6163SAl Viro if (parent == mnt) { 95048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9511da177e4SLinus Torvalds return 0; 9521da177e4SLinus Torvalds } 9530714a533SAl Viro mntget(&parent->mnt); 954a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 95548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 956bab77ebfSAl Viro dput(path->dentry); 957bab77ebfSAl Viro path->dentry = mountpoint; 958bab77ebfSAl Viro mntput(path->mnt); 9590714a533SAl Viro path->mnt = &parent->mnt; 9601da177e4SLinus Torvalds return 1; 9611da177e4SLinus Torvalds } 9624d359507SAl Viro EXPORT_SYMBOL(follow_up); 9631da177e4SLinus Torvalds 964b5c84bf6SNick Piggin /* 9659875cf80SDavid Howells * Perform an automount 9669875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9679875cf80SDavid Howells * were called with. 9681da177e4SLinus Torvalds */ 9699875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9709875cf80SDavid Howells bool *need_mntput) 97131e6b01fSNick Piggin { 9729875cf80SDavid Howells struct vfsmount *mnt; 973ea5b778aSDavid Howells int err; 9749875cf80SDavid Howells 9759875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9769875cf80SDavid Howells return -EREMOTE; 9779875cf80SDavid Howells 9780ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9790ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9800ec26fd0SMiklos Szeredi * the name. 9810ec26fd0SMiklos Szeredi * 9820ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9835a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9840ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9850ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9860ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9870ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9885a30d8a2SDavid Howells */ 9895a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 990d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9915a30d8a2SDavid Howells path->dentry->d_inode) 9929875cf80SDavid Howells return -EISDIR; 9930ec26fd0SMiklos Szeredi 9949875cf80SDavid Howells current->total_link_count++; 9959875cf80SDavid Howells if (current->total_link_count >= 40) 9969875cf80SDavid Howells return -ELOOP; 9979875cf80SDavid Howells 9989875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9999875cf80SDavid Howells if (IS_ERR(mnt)) { 10009875cf80SDavid Howells /* 10019875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10029875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10039875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10049875cf80SDavid Howells * 10059875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10069875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10079875cf80SDavid Howells * the path is inaccessible and we should say so. 10089875cf80SDavid Howells */ 100949084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 10109875cf80SDavid Howells return -EREMOTE; 10119875cf80SDavid Howells return PTR_ERR(mnt); 101231e6b01fSNick Piggin } 1013ea5b778aSDavid Howells 10149875cf80SDavid Howells if (!mnt) /* mount collision */ 10159875cf80SDavid Howells return 0; 10169875cf80SDavid Howells 10178aef1884SAl Viro if (!*need_mntput) { 10188aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10198aef1884SAl Viro mntget(path->mnt); 10208aef1884SAl Viro *need_mntput = true; 10218aef1884SAl Viro } 102219a167afSAl Viro err = finish_automount(mnt, path); 1023ea5b778aSDavid Howells 1024ea5b778aSDavid Howells switch (err) { 1025ea5b778aSDavid Howells case -EBUSY: 1026ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 102719a167afSAl Viro return 0; 1028ea5b778aSDavid Howells case 0: 10298aef1884SAl Viro path_put(path); 10309875cf80SDavid Howells path->mnt = mnt; 10319875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10329875cf80SDavid Howells return 0; 103319a167afSAl Viro default: 103419a167afSAl Viro return err; 10359875cf80SDavid Howells } 103619a167afSAl Viro 1037ea5b778aSDavid Howells } 10389875cf80SDavid Howells 10399875cf80SDavid Howells /* 10409875cf80SDavid Howells * Handle a dentry that is managed in some way. 1041cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10429875cf80SDavid Howells * - Flagged as mountpoint 10439875cf80SDavid Howells * - Flagged as automount point 10449875cf80SDavid Howells * 10459875cf80SDavid Howells * This may only be called in refwalk mode. 10469875cf80SDavid Howells * 10479875cf80SDavid Howells * Serialization is taken care of in namespace.c 10489875cf80SDavid Howells */ 10499875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10509875cf80SDavid Howells { 10518aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10529875cf80SDavid Howells unsigned managed; 10539875cf80SDavid Howells bool need_mntput = false; 10548aef1884SAl Viro int ret = 0; 10559875cf80SDavid Howells 10569875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10579875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10589875cf80SDavid Howells * the components of that value change under us */ 10599875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10609875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10619875cf80SDavid Howells unlikely(managed != 0)) { 1062cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1063cc53ce53SDavid Howells * being held. */ 1064cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1065cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1066cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10671aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1068cc53ce53SDavid Howells if (ret < 0) 10698aef1884SAl Viro break; 1070cc53ce53SDavid Howells } 1071cc53ce53SDavid Howells 10729875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10739875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10749875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10759875cf80SDavid Howells if (mounted) { 10769875cf80SDavid Howells dput(path->dentry); 10779875cf80SDavid Howells if (need_mntput) 1078463ffb2eSAl Viro mntput(path->mnt); 1079463ffb2eSAl Viro path->mnt = mounted; 1080463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10819875cf80SDavid Howells need_mntput = true; 10829875cf80SDavid Howells continue; 1083463ffb2eSAl Viro } 1084463ffb2eSAl Viro 10859875cf80SDavid Howells /* Something is mounted on this dentry in another 10869875cf80SDavid Howells * namespace and/or whatever was mounted there in this 108748a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 108848a066e7SAl Viro * get it */ 10891da177e4SLinus Torvalds } 10909875cf80SDavid Howells 10919875cf80SDavid Howells /* Handle an automount point */ 10929875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10939875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10949875cf80SDavid Howells if (ret < 0) 10958aef1884SAl Viro break; 10969875cf80SDavid Howells continue; 10979875cf80SDavid Howells } 10989875cf80SDavid Howells 10999875cf80SDavid Howells /* We didn't change the current path point */ 11009875cf80SDavid Howells break; 11019875cf80SDavid Howells } 11028aef1884SAl Viro 11038aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11048aef1884SAl Viro mntput(path->mnt); 11058aef1884SAl Viro if (ret == -EISDIR) 11068aef1884SAl Viro ret = 0; 1107a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 11081da177e4SLinus Torvalds } 11091da177e4SLinus Torvalds 1110cc53ce53SDavid Howells int follow_down_one(struct path *path) 11111da177e4SLinus Torvalds { 11121da177e4SLinus Torvalds struct vfsmount *mounted; 11131da177e4SLinus Torvalds 11141c755af4SAl Viro mounted = lookup_mnt(path); 11151da177e4SLinus Torvalds if (mounted) { 11169393bd07SAl Viro dput(path->dentry); 11179393bd07SAl Viro mntput(path->mnt); 11189393bd07SAl Viro path->mnt = mounted; 11199393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11201da177e4SLinus Torvalds return 1; 11211da177e4SLinus Torvalds } 11221da177e4SLinus Torvalds return 0; 11231da177e4SLinus Torvalds } 11244d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11251da177e4SLinus Torvalds 1126b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 112762a7375eSIan Kent { 1128b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1129b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 113062a7375eSIan Kent } 113162a7375eSIan Kent 11329875cf80SDavid Howells /* 1133287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1134287548e4SAl Viro * we meet a managed dentry that would need blocking. 11359875cf80SDavid Howells */ 11369875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1137287548e4SAl Viro struct inode **inode) 11389875cf80SDavid Howells { 113962a7375eSIan Kent for (;;) { 1140c7105365SAl Viro struct mount *mounted; 114162a7375eSIan Kent /* 114262a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 114362a7375eSIan Kent * that wants to block transit. 114462a7375eSIan Kent */ 1145b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1146b8faf035SNeilBrown case -ECHILD: 1147b8faf035SNeilBrown default: 1148ab90911fSDavid Howells return false; 1149b8faf035SNeilBrown case -EISDIR: 1150b8faf035SNeilBrown return true; 1151b8faf035SNeilBrown case 0: 1152b8faf035SNeilBrown break; 1153b8faf035SNeilBrown } 115462a7375eSIan Kent 115562a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1156b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 115762a7375eSIan Kent 1158474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11599875cf80SDavid Howells if (!mounted) 11609875cf80SDavid Howells break; 1161c7105365SAl Viro path->mnt = &mounted->mnt; 1162c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1163a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11649875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 116559430262SLinus Torvalds /* 116659430262SLinus Torvalds * Update the inode too. We don't need to re-check the 116759430262SLinus Torvalds * dentry sequence number here after this d_inode read, 116859430262SLinus Torvalds * because a mount-point is always pinned. 116959430262SLinus Torvalds */ 117059430262SLinus Torvalds *inode = path->dentry->d_inode; 11719875cf80SDavid Howells } 1172f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1173b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1174287548e4SAl Viro } 1175287548e4SAl Viro 117631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 117731e6b01fSNick Piggin { 11784023bfc9SAl Viro struct inode *inode = nd->inode; 11797bd88377SAl Viro if (!nd->root.mnt) 118031e6b01fSNick Piggin set_root_rcu(nd); 118131e6b01fSNick Piggin 118231e6b01fSNick Piggin while (1) { 118331e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 118431e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 118531e6b01fSNick Piggin break; 118631e6b01fSNick Piggin } 118731e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 118831e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 118931e6b01fSNick Piggin struct dentry *parent = old->d_parent; 119031e6b01fSNick Piggin unsigned seq; 119131e6b01fSNick Piggin 11924023bfc9SAl Viro inode = parent->d_inode; 119331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 119431e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1195ef7562d5SAl Viro goto failed; 119631e6b01fSNick Piggin nd->path.dentry = parent; 119731e6b01fSNick Piggin nd->seq = seq; 119831e6b01fSNick Piggin break; 119931e6b01fSNick Piggin } 120031e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 120131e6b01fSNick Piggin break; 12024023bfc9SAl Viro inode = nd->path.dentry->d_inode; 120331e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 120431e6b01fSNick Piggin } 1205b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1206b37199e6SAl Viro struct mount *mounted; 1207b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1208b37199e6SAl Viro if (!mounted) 1209b37199e6SAl Viro break; 1210b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1211b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12124023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1213b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1214f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1215b37199e6SAl Viro goto failed; 1216b37199e6SAl Viro } 12174023bfc9SAl Viro nd->inode = inode; 121831e6b01fSNick Piggin return 0; 1219ef7562d5SAl Viro 1220ef7562d5SAl Viro failed: 1221ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 12225b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1223ef7562d5SAl Viro nd->root.mnt = NULL; 12248b61e74fSAl Viro rcu_read_unlock(); 1225ef7562d5SAl Viro return -ECHILD; 122631e6b01fSNick Piggin } 122731e6b01fSNick Piggin 12289875cf80SDavid Howells /* 1229cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1230cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1231cc53ce53SDavid Howells * caller is permitted to proceed or not. 1232cc53ce53SDavid Howells */ 12337cc90cc3SAl Viro int follow_down(struct path *path) 1234cc53ce53SDavid Howells { 1235cc53ce53SDavid Howells unsigned managed; 1236cc53ce53SDavid Howells int ret; 1237cc53ce53SDavid Howells 1238cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1239cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1240cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1241cc53ce53SDavid Howells * being held. 1242cc53ce53SDavid Howells * 1243cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1244cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1245cc53ce53SDavid Howells * other than its daemon the right to mount on its 1246cc53ce53SDavid Howells * superstructure. 1247cc53ce53SDavid Howells * 1248cc53ce53SDavid Howells * The filesystem may sleep at this point. 1249cc53ce53SDavid Howells */ 1250cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1251cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1252cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1253ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12541aed3e42SAl Viro path->dentry, false); 1255cc53ce53SDavid Howells if (ret < 0) 1256cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1257cc53ce53SDavid Howells } 1258cc53ce53SDavid Howells 1259cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1260cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1261cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1262cc53ce53SDavid Howells if (!mounted) 1263cc53ce53SDavid Howells break; 1264cc53ce53SDavid Howells dput(path->dentry); 1265cc53ce53SDavid Howells mntput(path->mnt); 1266cc53ce53SDavid Howells path->mnt = mounted; 1267cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1268cc53ce53SDavid Howells continue; 1269cc53ce53SDavid Howells } 1270cc53ce53SDavid Howells 1271cc53ce53SDavid Howells /* Don't handle automount points here */ 1272cc53ce53SDavid Howells break; 1273cc53ce53SDavid Howells } 1274cc53ce53SDavid Howells return 0; 1275cc53ce53SDavid Howells } 12764d359507SAl Viro EXPORT_SYMBOL(follow_down); 1277cc53ce53SDavid Howells 1278cc53ce53SDavid Howells /* 12799875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12809875cf80SDavid Howells */ 12819875cf80SDavid Howells static void follow_mount(struct path *path) 12829875cf80SDavid Howells { 12839875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12849875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12859875cf80SDavid Howells if (!mounted) 12869875cf80SDavid Howells break; 12879875cf80SDavid Howells dput(path->dentry); 12889875cf80SDavid Howells mntput(path->mnt); 12899875cf80SDavid Howells path->mnt = mounted; 12909875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12919875cf80SDavid Howells } 12929875cf80SDavid Howells } 12939875cf80SDavid Howells 129431e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12951da177e4SLinus Torvalds { 12967bd88377SAl Viro if (!nd->root.mnt) 12972a737871SAl Viro set_root(nd); 1298e518ddb7SAndreas Mohr 12991da177e4SLinus Torvalds while(1) { 13004ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13011da177e4SLinus Torvalds 13022a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13032a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13041da177e4SLinus Torvalds break; 13051da177e4SLinus Torvalds } 13064ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13073088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13083088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13091da177e4SLinus Torvalds dput(old); 13101da177e4SLinus Torvalds break; 13111da177e4SLinus Torvalds } 13123088dd70SAl Viro if (!follow_up(&nd->path)) 13131da177e4SLinus Torvalds break; 13141da177e4SLinus Torvalds } 131579ed0226SAl Viro follow_mount(&nd->path); 131631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13171da177e4SLinus Torvalds } 13181da177e4SLinus Torvalds 13191da177e4SLinus Torvalds /* 1320bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1321bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1322bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1323bad61189SMiklos Szeredi * 1324bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1325baa03890SNick Piggin */ 1326bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1327201f956eSAl Viro unsigned int flags, bool *need_lookup) 1328baa03890SNick Piggin { 1329baa03890SNick Piggin struct dentry *dentry; 1330bad61189SMiklos Szeredi int error; 1331baa03890SNick Piggin 1332bad61189SMiklos Szeredi *need_lookup = false; 1333bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1334bad61189SMiklos Szeredi if (dentry) { 133539e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1336201f956eSAl Viro error = d_revalidate(dentry, flags); 1337bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1338bad61189SMiklos Szeredi if (error < 0) { 1339bad61189SMiklos Szeredi dput(dentry); 1340bad61189SMiklos Szeredi return ERR_PTR(error); 13415542aa2fSEric W. Biederman } else { 13425542aa2fSEric W. Biederman d_invalidate(dentry); 1343bad61189SMiklos Szeredi dput(dentry); 1344bad61189SMiklos Szeredi dentry = NULL; 1345bad61189SMiklos Szeredi } 1346bad61189SMiklos Szeredi } 1347bad61189SMiklos Szeredi } 1348bad61189SMiklos Szeredi } 1349baa03890SNick Piggin 1350bad61189SMiklos Szeredi if (!dentry) { 1351bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1352baa03890SNick Piggin if (unlikely(!dentry)) 1353baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1354baa03890SNick Piggin 1355bad61189SMiklos Szeredi *need_lookup = true; 1356baa03890SNick Piggin } 1357baa03890SNick Piggin return dentry; 1358baa03890SNick Piggin } 1359baa03890SNick Piggin 1360baa03890SNick Piggin /* 136113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 136213a2c3beSJ. Bruce Fields * unhashed. 1363bad61189SMiklos Szeredi * 1364bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 136544396f4bSJosef Bacik */ 1366bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 136772bd866aSAl Viro unsigned int flags) 136844396f4bSJosef Bacik { 136944396f4bSJosef Bacik struct dentry *old; 137044396f4bSJosef Bacik 137144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1372bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1373e188dc02SMiklos Szeredi dput(dentry); 137444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1375e188dc02SMiklos Szeredi } 137644396f4bSJosef Bacik 137772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 137844396f4bSJosef Bacik if (unlikely(old)) { 137944396f4bSJosef Bacik dput(dentry); 138044396f4bSJosef Bacik dentry = old; 138144396f4bSJosef Bacik } 138244396f4bSJosef Bacik return dentry; 138344396f4bSJosef Bacik } 138444396f4bSJosef Bacik 1385a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 138672bd866aSAl Viro struct dentry *base, unsigned int flags) 1387a3255546SAl Viro { 1388bad61189SMiklos Szeredi bool need_lookup; 1389a3255546SAl Viro struct dentry *dentry; 1390a3255546SAl Viro 139172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1392bad61189SMiklos Szeredi if (!need_lookup) 1393a3255546SAl Viro return dentry; 1394bad61189SMiklos Szeredi 139572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1396a3255546SAl Viro } 1397a3255546SAl Viro 139844396f4bSJosef Bacik /* 13991da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14001da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14011da177e4SLinus Torvalds * It _is_ time-critical. 14021da177e4SLinus Torvalds */ 1403e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 140431e6b01fSNick Piggin struct path *path, struct inode **inode) 14051da177e4SLinus Torvalds { 14064ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 140731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14085a18fff2SAl Viro int need_reval = 1; 14095a18fff2SAl Viro int status = 1; 14109875cf80SDavid Howells int err; 14119875cf80SDavid Howells 14123cac260aSAl Viro /* 1413b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1414b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1415b04f784eSNick Piggin * do the non-racy lookup, below. 1416b04f784eSNick Piggin */ 141731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 141831e6b01fSNick Piggin unsigned seq; 1419da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14205a18fff2SAl Viro if (!dentry) 14215a18fff2SAl Viro goto unlazy; 14225a18fff2SAl Viro 142312f8ad4bSLinus Torvalds /* 142412f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 142512f8ad4bSLinus Torvalds * the dentry name information from lookup. 142612f8ad4bSLinus Torvalds */ 142712f8ad4bSLinus Torvalds *inode = dentry->d_inode; 142812f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 142912f8ad4bSLinus Torvalds return -ECHILD; 143012f8ad4bSLinus Torvalds 143112f8ad4bSLinus Torvalds /* 143212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 143312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 143412f8ad4bSLinus Torvalds * 143512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 143612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 143712f8ad4bSLinus Torvalds */ 143831e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 143931e6b01fSNick Piggin return -ECHILD; 144031e6b01fSNick Piggin nd->seq = seq; 14415a18fff2SAl Viro 144224643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14434ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14445a18fff2SAl Viro if (unlikely(status <= 0)) { 14455a18fff2SAl Viro if (status != -ECHILD) 14465a18fff2SAl Viro need_reval = 0; 14475a18fff2SAl Viro goto unlazy; 14485a18fff2SAl Viro } 144924643087SAl Viro } 145031e6b01fSNick Piggin path->mnt = mnt; 145131e6b01fSNick Piggin path->dentry = dentry; 1452b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14539875cf80SDavid Howells return 0; 14545a18fff2SAl Viro unlazy: 145519660af7SAl Viro if (unlazy_walk(nd, dentry)) 14565a18fff2SAl Viro return -ECHILD; 14575a18fff2SAl Viro } else { 1458e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 145924643087SAl Viro } 14605a18fff2SAl Viro 146181e6f520SAl Viro if (unlikely(!dentry)) 146281e6f520SAl Viro goto need_lookup; 14635a18fff2SAl Viro 14645a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14654ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14665a18fff2SAl Viro if (unlikely(status <= 0)) { 14675a18fff2SAl Viro if (status < 0) { 14685a18fff2SAl Viro dput(dentry); 14695a18fff2SAl Viro return status; 14705a18fff2SAl Viro } 14715542aa2fSEric W. Biederman d_invalidate(dentry); 14725a18fff2SAl Viro dput(dentry); 147381e6f520SAl Viro goto need_lookup; 14745a18fff2SAl Viro } 1475697f514dSMiklos Szeredi 14761da177e4SLinus Torvalds path->mnt = mnt; 14771da177e4SLinus Torvalds path->dentry = dentry; 14789875cf80SDavid Howells err = follow_managed(path, nd->flags); 147989312214SIan Kent if (unlikely(err < 0)) { 148089312214SIan Kent path_put_conditional(path, nd); 14819875cf80SDavid Howells return err; 148289312214SIan Kent } 1483a3fbbde7SAl Viro if (err) 1484a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 148531e6b01fSNick Piggin *inode = path->dentry->d_inode; 14861da177e4SLinus Torvalds return 0; 148781e6f520SAl Viro 148881e6f520SAl Viro need_lookup: 1489697f514dSMiklos Szeredi return 1; 1490697f514dSMiklos Szeredi } 1491697f514dSMiklos Szeredi 1492697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1493cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1494697f514dSMiklos Szeredi { 1495697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1496697f514dSMiklos Szeredi int err; 1497697f514dSMiklos Szeredi 1498697f514dSMiklos Szeredi parent = nd->path.dentry; 149981e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 150081e6f520SAl Viro 150181e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1502cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 150381e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 150481e6f520SAl Viro if (IS_ERR(dentry)) 150581e6f520SAl Viro return PTR_ERR(dentry); 1506697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1507697f514dSMiklos Szeredi path->dentry = dentry; 1508697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1509697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1510697f514dSMiklos Szeredi path_put_conditional(path, nd); 1511697f514dSMiklos Szeredi return err; 1512697f514dSMiklos Szeredi } 1513697f514dSMiklos Szeredi if (err) 1514697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1515697f514dSMiklos Szeredi return 0; 15161da177e4SLinus Torvalds } 15171da177e4SLinus Torvalds 151852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 151952094c8aSAl Viro { 152052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15214ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 152252094c8aSAl Viro if (err != -ECHILD) 152352094c8aSAl Viro return err; 152419660af7SAl Viro if (unlazy_walk(nd, NULL)) 152552094c8aSAl Viro return -ECHILD; 152652094c8aSAl Viro } 15274ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152852094c8aSAl Viro } 152952094c8aSAl Viro 15309856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15319856fa1bSAl Viro { 15329856fa1bSAl Viro if (type == LAST_DOTDOT) { 15339856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15349856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15359856fa1bSAl Viro return -ECHILD; 15369856fa1bSAl Viro } else 15379856fa1bSAl Viro follow_dotdot(nd); 15389856fa1bSAl Viro } 15399856fa1bSAl Viro return 0; 15409856fa1bSAl Viro } 15419856fa1bSAl Viro 1542951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1543951361f9SAl Viro { 1544951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1545951361f9SAl Viro path_put(&nd->path); 1546951361f9SAl Viro } else { 1547951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15485b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1549951361f9SAl Viro nd->root.mnt = NULL; 15508b61e74fSAl Viro rcu_read_unlock(); 1551951361f9SAl Viro } 1552951361f9SAl Viro } 1553951361f9SAl Viro 15543ddcd056SLinus Torvalds /* 15553ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15563ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15573ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15583ddcd056SLinus Torvalds * for the common case. 15593ddcd056SLinus Torvalds */ 1560b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15613ddcd056SLinus Torvalds { 1562b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15633ddcd056SLinus Torvalds } 15643ddcd056SLinus Torvalds 1565ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 156621b9b073SAl Viro int follow) 1567ce57dfc1SAl Viro { 1568ce57dfc1SAl Viro struct inode *inode; 1569ce57dfc1SAl Viro int err; 1570ce57dfc1SAl Viro /* 1571ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1572ce57dfc1SAl Viro * to be able to know about the current root directory and 1573ce57dfc1SAl Viro * parent relationships. 1574ce57dfc1SAl Viro */ 157521b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 157621b9b073SAl Viro return handle_dots(nd, nd->last_type); 1577e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1578ce57dfc1SAl Viro if (unlikely(err)) { 1579697f514dSMiklos Szeredi if (err < 0) 1580697f514dSMiklos Szeredi goto out_err; 1581697f514dSMiklos Szeredi 1582cc2a5271SAl Viro err = lookup_slow(nd, path); 1583697f514dSMiklos Szeredi if (err < 0) 1584697f514dSMiklos Szeredi goto out_err; 1585697f514dSMiklos Szeredi 1586697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1587ce57dfc1SAl Viro } 1588697f514dSMiklos Szeredi err = -ENOENT; 158922213318SAl Viro if (!inode || d_is_negative(path->dentry)) 1590697f514dSMiklos Szeredi goto out_path_put; 1591697f514dSMiklos Szeredi 1592b18825a7SDavid Howells if (should_follow_link(path->dentry, follow)) { 159319660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 159419660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1595697f514dSMiklos Szeredi err = -ECHILD; 1596697f514dSMiklos Szeredi goto out_err; 159719660af7SAl Viro } 159819660af7SAl Viro } 1599ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1600ce57dfc1SAl Viro return 1; 1601ce57dfc1SAl Viro } 1602ce57dfc1SAl Viro path_to_nameidata(path, nd); 1603ce57dfc1SAl Viro nd->inode = inode; 1604ce57dfc1SAl Viro return 0; 1605697f514dSMiklos Szeredi 1606697f514dSMiklos Szeredi out_path_put: 1607697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1608697f514dSMiklos Szeredi out_err: 1609697f514dSMiklos Szeredi terminate_walk(nd); 1610697f514dSMiklos Szeredi return err; 1611ce57dfc1SAl Viro } 1612ce57dfc1SAl Viro 16131da177e4SLinus Torvalds /* 1614b356379aSAl Viro * This limits recursive symlink follows to 8, while 1615b356379aSAl Viro * limiting consecutive symlinks to 40. 1616b356379aSAl Viro * 1617b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1618b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1619b356379aSAl Viro */ 1620b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1621b356379aSAl Viro { 1622b356379aSAl Viro int res; 1623b356379aSAl Viro 1624b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1625b356379aSAl Viro path_put_conditional(path, nd); 1626b356379aSAl Viro path_put(&nd->path); 1627b356379aSAl Viro return -ELOOP; 1628b356379aSAl Viro } 16291a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1630b356379aSAl Viro 1631b356379aSAl Viro nd->depth++; 1632b356379aSAl Viro current->link_count++; 1633b356379aSAl Viro 1634b356379aSAl Viro do { 1635b356379aSAl Viro struct path link = *path; 1636b356379aSAl Viro void *cookie; 1637574197e0SAl Viro 1638574197e0SAl Viro res = follow_link(&link, nd, &cookie); 16396d7b5aaeSAl Viro if (res) 16406d7b5aaeSAl Viro break; 164121b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1642574197e0SAl Viro put_link(nd, &link, cookie); 1643b356379aSAl Viro } while (res > 0); 1644b356379aSAl Viro 1645b356379aSAl Viro current->link_count--; 1646b356379aSAl Viro nd->depth--; 1647b356379aSAl Viro return res; 1648b356379aSAl Viro } 1649b356379aSAl Viro 1650b356379aSAl Viro /* 1651bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1652bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1653bfcfaa77SLinus Torvalds * 1654bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1655bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1656bfcfaa77SLinus Torvalds * fast. 1657bfcfaa77SLinus Torvalds * 1658bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1659bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1660bfcfaa77SLinus Torvalds * crossing operation. 1661bfcfaa77SLinus Torvalds * 1662bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1663bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1664bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1665bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1666bfcfaa77SLinus Torvalds */ 1667bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1668bfcfaa77SLinus Torvalds 1669f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1670bfcfaa77SLinus Torvalds 1671f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1674bfcfaa77SLinus Torvalds { 167599d263d4SLinus Torvalds return hash_64(hash, 32); 1676bfcfaa77SLinus Torvalds } 1677bfcfaa77SLinus Torvalds 1678bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1679bfcfaa77SLinus Torvalds 1680bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1681bfcfaa77SLinus Torvalds 1682bfcfaa77SLinus Torvalds #endif 1683bfcfaa77SLinus Torvalds 1684bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1685bfcfaa77SLinus Torvalds { 1686bfcfaa77SLinus Torvalds unsigned long a, mask; 1687bfcfaa77SLinus Torvalds unsigned long hash = 0; 1688bfcfaa77SLinus Torvalds 1689bfcfaa77SLinus Torvalds for (;;) { 1690e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1691bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1692bfcfaa77SLinus Torvalds break; 1693bfcfaa77SLinus Torvalds hash += a; 1694f132c5beSAl Viro hash *= 9; 1695bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1696bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1697bfcfaa77SLinus Torvalds if (!len) 1698bfcfaa77SLinus Torvalds goto done; 1699bfcfaa77SLinus Torvalds } 1700a5c21dceSWill Deacon mask = bytemask_from_count(len); 1701bfcfaa77SLinus Torvalds hash += mask & a; 1702bfcfaa77SLinus Torvalds done: 1703bfcfaa77SLinus Torvalds return fold_hash(hash); 1704bfcfaa77SLinus Torvalds } 1705bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1706bfcfaa77SLinus Torvalds 1707bfcfaa77SLinus Torvalds /* 1708bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1709d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1710bfcfaa77SLinus Torvalds */ 1711d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1712bfcfaa77SLinus Torvalds { 171336126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 171436126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1715bfcfaa77SLinus Torvalds 1716bfcfaa77SLinus Torvalds hash = a = 0; 1717bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1718bfcfaa77SLinus Torvalds do { 1719bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1720bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1721e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 172236126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 172336126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1724bfcfaa77SLinus Torvalds 172536126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 172636126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172736126f8fSLinus Torvalds 172836126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 172936126f8fSLinus Torvalds 173036126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17319226b5b4SLinus Torvalds len += find_zero(mask); 1732d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1733bfcfaa77SLinus Torvalds } 1734bfcfaa77SLinus Torvalds 1735bfcfaa77SLinus Torvalds #else 1736bfcfaa77SLinus Torvalds 17370145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17380145acc2SLinus Torvalds { 17390145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17400145acc2SLinus Torvalds while (len--) 17410145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17420145acc2SLinus Torvalds return end_name_hash(hash); 17430145acc2SLinus Torvalds } 1744ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17450145acc2SLinus Torvalds 17463ddcd056SLinus Torvalds /* 1747200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1748200e9ef7SLinus Torvalds * one character. 1749200e9ef7SLinus Torvalds */ 1750d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1751200e9ef7SLinus Torvalds { 1752200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1753200e9ef7SLinus Torvalds unsigned long len = 0, c; 1754200e9ef7SLinus Torvalds 1755200e9ef7SLinus Torvalds c = (unsigned char)*name; 1756200e9ef7SLinus Torvalds do { 1757200e9ef7SLinus Torvalds len++; 1758200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1759200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1760200e9ef7SLinus Torvalds } while (c && c != '/'); 1761d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1762200e9ef7SLinus Torvalds } 1763200e9ef7SLinus Torvalds 1764bfcfaa77SLinus Torvalds #endif 1765bfcfaa77SLinus Torvalds 1766200e9ef7SLinus Torvalds /* 17671da177e4SLinus Torvalds * Name resolution. 1768ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1769ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17701da177e4SLinus Torvalds * 1771ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1772ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17731da177e4SLinus Torvalds */ 17746de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17751da177e4SLinus Torvalds { 17761da177e4SLinus Torvalds struct path next; 17771da177e4SLinus Torvalds int err; 17781da177e4SLinus Torvalds 17791da177e4SLinus Torvalds while (*name=='/') 17801da177e4SLinus Torvalds name++; 17811da177e4SLinus Torvalds if (!*name) 1782086e183aSAl Viro return 0; 17831da177e4SLinus Torvalds 17841da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17851da177e4SLinus Torvalds for(;;) { 1786d6bb3e90SLinus Torvalds u64 hash_len; 1787fe479a58SAl Viro int type; 17881da177e4SLinus Torvalds 178952094c8aSAl Viro err = may_lookup(nd); 17901da177e4SLinus Torvalds if (err) 17911da177e4SLinus Torvalds break; 17921da177e4SLinus Torvalds 1793d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17941da177e4SLinus Torvalds 1795fe479a58SAl Viro type = LAST_NORM; 1796d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1797fe479a58SAl Viro case 2: 1798200e9ef7SLinus Torvalds if (name[1] == '.') { 1799fe479a58SAl Viro type = LAST_DOTDOT; 180016c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 180116c2cd71SAl Viro } 1802fe479a58SAl Viro break; 1803fe479a58SAl Viro case 1: 1804fe479a58SAl Viro type = LAST_DOT; 1805fe479a58SAl Viro } 18065a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18075a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180816c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18095a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1810a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1811da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18125a202bcdSAl Viro if (err < 0) 18135a202bcdSAl Viro break; 1814d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1815d6bb3e90SLinus Torvalds name = this.name; 18165a202bcdSAl Viro } 18175a202bcdSAl Viro } 1818fe479a58SAl Viro 1819d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1820d6bb3e90SLinus Torvalds nd->last.name = name; 18215f4a6a69SAl Viro nd->last_type = type; 18225f4a6a69SAl Viro 1823d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1824d6bb3e90SLinus Torvalds if (!*name) 18255f4a6a69SAl Viro return 0; 1826200e9ef7SLinus Torvalds /* 1827200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1828200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1829200e9ef7SLinus Torvalds */ 1830200e9ef7SLinus Torvalds do { 1831d6bb3e90SLinus Torvalds name++; 1832d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1833d6bb3e90SLinus Torvalds if (!*name) 18345f4a6a69SAl Viro return 0; 18355f4a6a69SAl Viro 183621b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1837ce57dfc1SAl Viro if (err < 0) 1838ce57dfc1SAl Viro return err; 1839fe479a58SAl Viro 1840ce57dfc1SAl Viro if (err) { 1841b356379aSAl Viro err = nested_symlink(&next, nd); 18421da177e4SLinus Torvalds if (err) 1843a7472babSAl Viro return err; 184431e6b01fSNick Piggin } 184544b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18463ddcd056SLinus Torvalds err = -ENOTDIR; 18473ddcd056SLinus Torvalds break; 18485f4a6a69SAl Viro } 1849ce57dfc1SAl Viro } 1850951361f9SAl Viro terminate_walk(nd); 18511da177e4SLinus Torvalds return err; 18521da177e4SLinus Torvalds } 18531da177e4SLinus Torvalds 185470e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 18555e53084dSAl Viro struct nameidata *nd) 185631e6b01fSNick Piggin { 185731e6b01fSNick Piggin int retval = 0; 185831e6b01fSNick Piggin 185931e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1860980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 186131e6b01fSNick Piggin nd->depth = 0; 18625e53084dSAl Viro nd->base = NULL; 18635b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1864b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1865b18825a7SDavid Howells struct inode *inode = root->d_inode; 186673d049a4SAl Viro if (*name) { 186744b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18685b6ca027SAl Viro return -ENOTDIR; 18695b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18705b6ca027SAl Viro if (retval) 18715b6ca027SAl Viro return retval; 187273d049a4SAl Viro } 18735b6ca027SAl Viro nd->path = nd->root; 18745b6ca027SAl Viro nd->inode = inode; 18755b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18768b61e74fSAl Viro rcu_read_lock(); 18775b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 187848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18795b6ca027SAl Viro } else { 18805b6ca027SAl Viro path_get(&nd->path); 18815b6ca027SAl Viro } 1882d465887fSAl Viro goto done; 18835b6ca027SAl Viro } 18845b6ca027SAl Viro 188531e6b01fSNick Piggin nd->root.mnt = NULL; 188631e6b01fSNick Piggin 188748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 188831e6b01fSNick Piggin if (*name=='/') { 1889e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18908b61e74fSAl Viro rcu_read_lock(); 18917bd88377SAl Viro nd->seq = set_root_rcu(nd); 1892e41f7d4eSAl Viro } else { 1893e41f7d4eSAl Viro set_root(nd); 1894e41f7d4eSAl Viro path_get(&nd->root); 1895e41f7d4eSAl Viro } 189631e6b01fSNick Piggin nd->path = nd->root; 189731e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1898e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 189931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1900c28cc364SNick Piggin unsigned seq; 190131e6b01fSNick Piggin 19028b61e74fSAl Viro rcu_read_lock(); 190331e6b01fSNick Piggin 1904c28cc364SNick Piggin do { 1905c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 190631e6b01fSNick Piggin nd->path = fs->pwd; 1907c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1908c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1909e41f7d4eSAl Viro } else { 1910e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1911e41f7d4eSAl Viro } 191231e6b01fSNick Piggin } else { 1913582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19142903ff01SAl Viro struct fd f = fdget_raw(dfd); 191531e6b01fSNick Piggin struct dentry *dentry; 191631e6b01fSNick Piggin 19172903ff01SAl Viro if (!f.file) 19182903ff01SAl Viro return -EBADF; 191931e6b01fSNick Piggin 19202903ff01SAl Viro dentry = f.file->f_path.dentry; 192131e6b01fSNick Piggin 1922f52e0c11SAl Viro if (*name) { 192344b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19242903ff01SAl Viro fdput(f); 19252903ff01SAl Viro return -ENOTDIR; 1926f52e0c11SAl Viro } 19272903ff01SAl Viro } 19282903ff01SAl Viro 19292903ff01SAl Viro nd->path = f.file->f_path; 1930e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19319c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19325e53084dSAl Viro nd->base = f.file; 1933c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19348b61e74fSAl Viro rcu_read_lock(); 19355590ff0dSUlrich Drepper } else { 19362903ff01SAl Viro path_get(&nd->path); 19372903ff01SAl Viro fdput(f); 19381da177e4SLinus Torvalds } 1939e41f7d4eSAl Viro } 1940e41f7d4eSAl Viro 194131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19424023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1943d465887fSAl Viro goto done; 19444023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1945d465887fSAl Viro goto done; 19464023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19474023bfc9SAl Viro nd->root.mnt = NULL; 19484023bfc9SAl Viro rcu_read_unlock(); 19494023bfc9SAl Viro return -ECHILD; 1950d465887fSAl Viro done: 1951d465887fSAl Viro current->total_link_count = 0; 1952d465887fSAl Viro return link_path_walk(name, nd); 19539b4a9b14SAl Viro } 19549b4a9b14SAl Viro 1955893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1956893b7775SAl Viro { 1957893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1958893b7775SAl Viro path_put(&nd->root); 1959893b7775SAl Viro nd->root.mnt = NULL; 1960893b7775SAl Viro } 1961893b7775SAl Viro if (unlikely(nd->base)) 1962893b7775SAl Viro fput(nd->base); 19639b4a9b14SAl Viro } 19649b4a9b14SAl Viro 1965bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1966bd92d7feSAl Viro { 1967bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1968bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1969bd92d7feSAl Viro 1970bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 197121b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1972bd92d7feSAl Viro } 1973bd92d7feSAl Viro 19749b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1975ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19769b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19779b4a9b14SAl Viro { 1978bd92d7feSAl Viro struct path path; 1979bd92d7feSAl Viro int err; 198031e6b01fSNick Piggin 198131e6b01fSNick Piggin /* 198231e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 198331e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 198431e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 198531e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 198631e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 198731e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 198831e6b01fSNick Piggin * analogue, foo_rcu(). 198931e6b01fSNick Piggin * 199031e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 199131e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 199231e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 199331e6b01fSNick Piggin * be able to complete). 199431e6b01fSNick Piggin */ 1995980f3ea2SAl Viro err = path_init(dfd, name, flags, nd); 1996bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1997bd92d7feSAl Viro err = lookup_last(nd, &path); 1998bd92d7feSAl Viro while (err > 0) { 1999bd92d7feSAl Viro void *cookie; 2000bd92d7feSAl Viro struct path link = path; 2001800179c9SKees Cook err = may_follow_link(&link, nd); 2002800179c9SKees Cook if (unlikely(err)) 2003800179c9SKees Cook break; 2004bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 2005574197e0SAl Viro err = follow_link(&link, nd, &cookie); 20066d7b5aaeSAl Viro if (err) 20076d7b5aaeSAl Viro break; 2008bd92d7feSAl Viro err = lookup_last(nd, &path); 2009574197e0SAl Viro put_link(nd, &link, cookie); 2010bd92d7feSAl Viro } 2011bd92d7feSAl Viro } 2012ee0827cdSAl Viro 20139f1fafeeSAl Viro if (!err) 20149f1fafeeSAl Viro err = complete_walk(nd); 2015bd92d7feSAl Viro 2016bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 201744b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2018bd92d7feSAl Viro path_put(&nd->path); 2019bd23a539SAl Viro err = -ENOTDIR; 2020bd92d7feSAl Viro } 2021bd92d7feSAl Viro } 202216c2cd71SAl Viro 2023893b7775SAl Viro path_cleanup(nd); 2024bd92d7feSAl Viro return err; 202531e6b01fSNick Piggin } 202631e6b01fSNick Piggin 2027873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2028873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2029873f1eedSJeff Layton { 2030873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 2031873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2032873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 2033873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2034873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 2035873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 2036873f1eedSJeff Layton 2037873f1eedSJeff Layton if (likely(!retval)) 2038adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2039873f1eedSJeff Layton return retval; 2040873f1eedSJeff Layton } 2041873f1eedSJeff Layton 2042ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 2043ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 2044ee0827cdSAl Viro { 2045873f1eedSJeff Layton struct filename filename = { .name = name }; 2046ee0827cdSAl Viro 2047873f1eedSJeff Layton return filename_lookup(dfd, &filename, flags, nd); 20481da177e4SLinus Torvalds } 20491da177e4SLinus Torvalds 205079714f72SAl Viro /* does lookup, returns the object with parent locked */ 205179714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20525590ff0dSUlrich Drepper { 205379714f72SAl Viro struct nameidata nd; 205479714f72SAl Viro struct dentry *d; 2055fa14a0b8SAl Viro struct filename filename = {.name = name}; 2056fa14a0b8SAl Viro int err = filename_lookup(AT_FDCWD, &filename, LOOKUP_PARENT, &nd); 205779714f72SAl Viro if (err) 205879714f72SAl Viro return ERR_PTR(err); 205979714f72SAl Viro if (nd.last_type != LAST_NORM) { 206079714f72SAl Viro path_put(&nd.path); 206179714f72SAl Viro return ERR_PTR(-EINVAL); 206279714f72SAl Viro } 206379714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20641e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 206579714f72SAl Viro if (IS_ERR(d)) { 206679714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 206779714f72SAl Viro path_put(&nd.path); 206879714f72SAl Viro return d; 206979714f72SAl Viro } 207079714f72SAl Viro *path = nd.path; 207179714f72SAl Viro return d; 20725590ff0dSUlrich Drepper } 20735590ff0dSUlrich Drepper 2074d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2075d1811465SAl Viro { 2076d1811465SAl Viro struct nameidata nd; 2077d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2078d1811465SAl Viro if (!res) 2079d1811465SAl Viro *path = nd.path; 2080d1811465SAl Viro return res; 2081d1811465SAl Viro } 20824d359507SAl Viro EXPORT_SYMBOL(kern_path); 2083d1811465SAl Viro 208416f18200SJosef 'Jeff' Sipek /** 208516f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 208616f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 208716f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 208816f18200SJosef 'Jeff' Sipek * @name: pointer to file name 208916f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2090e0a01249SAl Viro * @path: pointer to struct path to fill 209116f18200SJosef 'Jeff' Sipek */ 209216f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 209316f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2094e0a01249SAl Viro struct path *path) 209516f18200SJosef 'Jeff' Sipek { 2096e0a01249SAl Viro struct nameidata nd; 2097e0a01249SAl Viro int err; 2098e0a01249SAl Viro nd.root.dentry = dentry; 2099e0a01249SAl Viro nd.root.mnt = mnt; 2100e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21015b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2102e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2103e0a01249SAl Viro if (!err) 2104e0a01249SAl Viro *path = nd.path; 2105e0a01249SAl Viro return err; 210616f18200SJosef 'Jeff' Sipek } 21074d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 210816f18200SJosef 'Jeff' Sipek 2109057f6c01SJames Morris /* 2110057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2111057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2112057f6c01SJames Morris * SMP-safe. 2113057f6c01SJames Morris */ 2114a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 21151da177e4SLinus Torvalds { 211672bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 21171da177e4SLinus Torvalds } 21181da177e4SLinus Torvalds 2119eead1911SChristoph Hellwig /** 2120a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2121eead1911SChristoph Hellwig * @name: pathname component to lookup 2122eead1911SChristoph Hellwig * @base: base directory to lookup from 2123eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2124eead1911SChristoph Hellwig * 2125a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2126a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2127eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2128eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2129eead1911SChristoph Hellwig */ 2130057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2131057f6c01SJames Morris { 2132057f6c01SJames Morris struct qstr this; 21336a96ba54SAl Viro unsigned int c; 2134cda309deSMiklos Szeredi int err; 2135057f6c01SJames Morris 21362f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21372f9092e1SDavid Woodhouse 21386a96ba54SAl Viro this.name = name; 21396a96ba54SAl Viro this.len = len; 21400145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21416a96ba54SAl Viro if (!len) 21426a96ba54SAl Viro return ERR_PTR(-EACCES); 21436a96ba54SAl Viro 214421d8a15aSAl Viro if (unlikely(name[0] == '.')) { 214521d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 214621d8a15aSAl Viro return ERR_PTR(-EACCES); 214721d8a15aSAl Viro } 214821d8a15aSAl Viro 21496a96ba54SAl Viro while (len--) { 21506a96ba54SAl Viro c = *(const unsigned char *)name++; 21516a96ba54SAl Viro if (c == '/' || c == '\0') 21526a96ba54SAl Viro return ERR_PTR(-EACCES); 21536a96ba54SAl Viro } 21545a202bcdSAl Viro /* 21555a202bcdSAl Viro * See if the low-level filesystem might want 21565a202bcdSAl Viro * to use its own hash.. 21575a202bcdSAl Viro */ 21585a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2159da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21605a202bcdSAl Viro if (err < 0) 21615a202bcdSAl Viro return ERR_PTR(err); 21625a202bcdSAl Viro } 2163eead1911SChristoph Hellwig 2164cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2165cda309deSMiklos Szeredi if (err) 2166cda309deSMiklos Szeredi return ERR_PTR(err); 2167cda309deSMiklos Szeredi 216872bd866aSAl Viro return __lookup_hash(&this, base, 0); 2169057f6c01SJames Morris } 21704d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2171057f6c01SJames Morris 21721fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21731fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21741da177e4SLinus Torvalds { 21752d8f3038SAl Viro struct nameidata nd; 217691a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21771da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21781da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21792d8f3038SAl Viro 21802d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21812d8f3038SAl Viro 2182873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21831da177e4SLinus Torvalds putname(tmp); 21842d8f3038SAl Viro if (!err) 21852d8f3038SAl Viro *path = nd.path; 21861da177e4SLinus Torvalds } 21871da177e4SLinus Torvalds return err; 21881da177e4SLinus Torvalds } 21891da177e4SLinus Torvalds 21901fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 21911fa1e7f6SAndy Whitcroft struct path *path) 21921fa1e7f6SAndy Whitcroft { 2193f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 21941fa1e7f6SAndy Whitcroft } 21954d359507SAl Viro EXPORT_SYMBOL(user_path_at); 21961fa1e7f6SAndy Whitcroft 2197873f1eedSJeff Layton /* 2198873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2199873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2200873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2201873f1eedSJeff Layton * path-walking is complete. 2202873f1eedSJeff Layton */ 220391a27b2aSJeff Layton static struct filename * 22049e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 22059e790bd6SJeff Layton unsigned int flags) 22062ad94ae6SAl Viro { 220791a27b2aSJeff Layton struct filename *s = getname(path); 22082ad94ae6SAl Viro int error; 22092ad94ae6SAl Viro 22109e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22119e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22129e790bd6SJeff Layton 22132ad94ae6SAl Viro if (IS_ERR(s)) 221491a27b2aSJeff Layton return s; 22152ad94ae6SAl Viro 22169e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 221791a27b2aSJeff Layton if (error) { 22182ad94ae6SAl Viro putname(s); 221991a27b2aSJeff Layton return ERR_PTR(error); 222091a27b2aSJeff Layton } 22212ad94ae6SAl Viro 222291a27b2aSJeff Layton return s; 22232ad94ae6SAl Viro } 22242ad94ae6SAl Viro 22258033426eSJeff Layton /** 2226197df04cSAl Viro * mountpoint_last - look up last component for umount 22278033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22288033426eSJeff Layton * @path: pointer to container for result 22298033426eSJeff Layton * 22308033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22318033426eSJeff Layton * need to resolve the path without doing any revalidation. 22328033426eSJeff Layton * 22338033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22348033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22358033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22368033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22378033426eSJeff Layton * bogus and it doesn't exist. 22388033426eSJeff Layton * 22398033426eSJeff Layton * Returns: 22408033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22418033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22428033426eSJeff Layton * put in this case. 22438033426eSJeff Layton * 22448033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22458033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22468033426eSJeff Layton * The nd->path reference will also be put. 22478033426eSJeff Layton * 22488033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22498033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22508033426eSJeff Layton * to the link, and nd->path will *not* be put. 22518033426eSJeff Layton */ 22528033426eSJeff Layton static int 2253197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22548033426eSJeff Layton { 22558033426eSJeff Layton int error = 0; 22568033426eSJeff Layton struct dentry *dentry; 22578033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22588033426eSJeff Layton 225935759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 226035759521SAl Viro if (nd->flags & LOOKUP_RCU) { 226135759521SAl Viro if (unlazy_walk(nd, NULL)) { 22628033426eSJeff Layton error = -ECHILD; 226335759521SAl Viro goto out; 226435759521SAl Viro } 22658033426eSJeff Layton } 22668033426eSJeff Layton 22678033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22688033426eSJeff Layton 22698033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22708033426eSJeff Layton error = handle_dots(nd, nd->last_type); 227135759521SAl Viro if (error) 227235759521SAl Viro goto out; 22738033426eSJeff Layton dentry = dget(nd->path.dentry); 227435759521SAl Viro goto done; 22758033426eSJeff Layton } 22768033426eSJeff Layton 22778033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22788033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22798033426eSJeff Layton if (!dentry) { 22808033426eSJeff Layton /* 22818033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22828033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22838033426eSJeff Layton * path doesn't actually point to a mounted dentry. 22848033426eSJeff Layton */ 22858033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 22868033426eSJeff Layton if (!dentry) { 22878033426eSJeff Layton error = -ENOMEM; 2288bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 228935759521SAl Viro goto out; 22908033426eSJeff Layton } 229135759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 229235759521SAl Viro error = PTR_ERR(dentry); 2293bcceeebaSDave Jones if (IS_ERR(dentry)) { 2294bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 229535759521SAl Viro goto out; 22968033426eSJeff Layton } 2297bcceeebaSDave Jones } 22988033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 22998033426eSJeff Layton 230035759521SAl Viro done: 230122213318SAl Viro if (!dentry->d_inode || d_is_negative(dentry)) { 23028033426eSJeff Layton error = -ENOENT; 23038033426eSJeff Layton dput(dentry); 230435759521SAl Viro goto out; 230535759521SAl Viro } 23068033426eSJeff Layton path->dentry = dentry; 2307295dc39dSVasily Averin path->mnt = nd->path.mnt; 2308b18825a7SDavid Howells if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) 23098033426eSJeff Layton return 1; 2310295dc39dSVasily Averin mntget(path->mnt); 23118033426eSJeff Layton follow_mount(path); 231235759521SAl Viro error = 0; 231335759521SAl Viro out: 23148033426eSJeff Layton terminate_walk(nd); 23158033426eSJeff Layton return error; 23168033426eSJeff Layton } 23178033426eSJeff Layton 23188033426eSJeff Layton /** 2319197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23208033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23218033426eSJeff Layton * @name: full pathname to walk 2322606d6fe3SRandy Dunlap * @path: pointer to container for result 23238033426eSJeff Layton * @flags: lookup flags 23248033426eSJeff Layton * 23258033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2326606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23278033426eSJeff Layton */ 23288033426eSJeff Layton static int 2329197df04cSAl Viro path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) 23308033426eSJeff Layton { 23318033426eSJeff Layton struct nameidata nd; 23328033426eSJeff Layton int err; 23338033426eSJeff Layton 2334980f3ea2SAl Viro err = path_init(dfd, name, flags, &nd); 23358033426eSJeff Layton if (unlikely(err)) 2336115cbfdcSAl Viro goto out; 23378033426eSJeff Layton 2338197df04cSAl Viro err = mountpoint_last(&nd, path); 23398033426eSJeff Layton while (err > 0) { 23408033426eSJeff Layton void *cookie; 23418033426eSJeff Layton struct path link = *path; 23428033426eSJeff Layton err = may_follow_link(&link, &nd); 23438033426eSJeff Layton if (unlikely(err)) 23448033426eSJeff Layton break; 23458033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 23468033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 23478033426eSJeff Layton if (err) 23488033426eSJeff Layton break; 2349197df04cSAl Viro err = mountpoint_last(&nd, path); 23508033426eSJeff Layton put_link(&nd, &link, cookie); 23518033426eSJeff Layton } 23528033426eSJeff Layton out: 2353893b7775SAl Viro path_cleanup(&nd); 23548033426eSJeff Layton return err; 23558033426eSJeff Layton } 23568033426eSJeff Layton 23572d864651SAl Viro static int 23582d864651SAl Viro filename_mountpoint(int dfd, struct filename *s, struct path *path, 23592d864651SAl Viro unsigned int flags) 23602d864651SAl Viro { 23612d864651SAl Viro int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); 23622d864651SAl Viro if (unlikely(error == -ECHILD)) 23632d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags); 23642d864651SAl Viro if (unlikely(error == -ESTALE)) 23652d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); 23662d864651SAl Viro if (likely(!error)) 23672d864651SAl Viro audit_inode(s, path->dentry, 0); 23682d864651SAl Viro return error; 23692d864651SAl Viro } 23702d864651SAl Viro 23718033426eSJeff Layton /** 2372197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 23738033426eSJeff Layton * @dfd: directory file descriptor 23748033426eSJeff Layton * @name: pathname from userland 23758033426eSJeff Layton * @flags: lookup flags 23768033426eSJeff Layton * @path: pointer to container to hold result 23778033426eSJeff Layton * 23788033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23798033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 23808033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 23818033426eSJeff Layton * and avoid revalidating the last component. 23828033426eSJeff Layton * 23838033426eSJeff Layton * Returns 0 and populates "path" on success. 23848033426eSJeff Layton */ 23858033426eSJeff Layton int 2386197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 23878033426eSJeff Layton struct path *path) 23888033426eSJeff Layton { 23898033426eSJeff Layton struct filename *s = getname(name); 23908033426eSJeff Layton int error; 23918033426eSJeff Layton if (IS_ERR(s)) 23928033426eSJeff Layton return PTR_ERR(s); 23932d864651SAl Viro error = filename_mountpoint(dfd, s, path, flags); 23948033426eSJeff Layton putname(s); 23958033426eSJeff Layton return error; 23968033426eSJeff Layton } 23978033426eSJeff Layton 23982d864651SAl Viro int 23992d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24002d864651SAl Viro unsigned int flags) 24012d864651SAl Viro { 24022d864651SAl Viro struct filename s = {.name = name}; 24032d864651SAl Viro return filename_mountpoint(dfd, &s, path, flags); 24042d864651SAl Viro } 24052d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24062d864651SAl Viro 2407cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24081da177e4SLinus Torvalds { 24098e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2410da9592edSDavid Howells 24118e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24121da177e4SLinus Torvalds return 0; 24138e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24141da177e4SLinus Torvalds return 0; 241523adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24161da177e4SLinus Torvalds } 2417cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24181da177e4SLinus Torvalds 24191da177e4SLinus Torvalds /* 24201da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24211da177e4SLinus Torvalds * whether the type of victim is right. 24221da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24231da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24241da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24251da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24261da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24271da177e4SLinus Torvalds * a. be owner of dir, or 24281da177e4SLinus Torvalds * b. be owner of victim, or 24291da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24301da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24311da177e4SLinus Torvalds * links pointing to it. 24321da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24331da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24341da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24351da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24361da177e4SLinus Torvalds * nfs_async_unlink(). 24371da177e4SLinus Torvalds */ 2438b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24391da177e4SLinus Torvalds { 2440b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24411da177e4SLinus Torvalds int error; 24421da177e4SLinus Torvalds 2443b18825a7SDavid Howells if (d_is_negative(victim)) 24441da177e4SLinus Torvalds return -ENOENT; 2445b18825a7SDavid Howells BUG_ON(!inode); 24461da177e4SLinus Torvalds 24471da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24484fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24491da177e4SLinus Torvalds 2450f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24511da177e4SLinus Torvalds if (error) 24521da177e4SLinus Torvalds return error; 24531da177e4SLinus Torvalds if (IS_APPEND(dir)) 24541da177e4SLinus Torvalds return -EPERM; 2455b18825a7SDavid Howells 2456b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2457b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24581da177e4SLinus Torvalds return -EPERM; 24591da177e4SLinus Torvalds if (isdir) { 246044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24611da177e4SLinus Torvalds return -ENOTDIR; 24621da177e4SLinus Torvalds if (IS_ROOT(victim)) 24631da177e4SLinus Torvalds return -EBUSY; 246444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24651da177e4SLinus Torvalds return -EISDIR; 24661da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24671da177e4SLinus Torvalds return -ENOENT; 24681da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24691da177e4SLinus Torvalds return -EBUSY; 24701da177e4SLinus Torvalds return 0; 24711da177e4SLinus Torvalds } 24721da177e4SLinus Torvalds 24731da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24741da177e4SLinus Torvalds * dir. 24751da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24761da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24771da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24781da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24791da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24801da177e4SLinus Torvalds */ 2481a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24821da177e4SLinus Torvalds { 248314e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 24841da177e4SLinus Torvalds if (child->d_inode) 24851da177e4SLinus Torvalds return -EEXIST; 24861da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24871da177e4SLinus Torvalds return -ENOENT; 2488f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 24891da177e4SLinus Torvalds } 24901da177e4SLinus Torvalds 24911da177e4SLinus Torvalds /* 24921da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 24931da177e4SLinus Torvalds */ 24941da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 24951da177e4SLinus Torvalds { 24961da177e4SLinus Torvalds struct dentry *p; 24971da177e4SLinus Torvalds 24981da177e4SLinus Torvalds if (p1 == p2) { 2499f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25001da177e4SLinus Torvalds return NULL; 25011da177e4SLinus Torvalds } 25021da177e4SLinus Torvalds 2503a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25041da177e4SLinus Torvalds 2505e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2506e2761a11SOGAWA Hirofumi if (p) { 2507f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2508f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25091da177e4SLinus Torvalds return p; 25101da177e4SLinus Torvalds } 25111da177e4SLinus Torvalds 2512e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2513e2761a11SOGAWA Hirofumi if (p) { 2514f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2515f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25161da177e4SLinus Torvalds return p; 25171da177e4SLinus Torvalds } 25181da177e4SLinus Torvalds 2519f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2520d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25211da177e4SLinus Torvalds return NULL; 25221da177e4SLinus Torvalds } 25234d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25241da177e4SLinus Torvalds 25251da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25261da177e4SLinus Torvalds { 25271b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25281da177e4SLinus Torvalds if (p1 != p2) { 25291b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2530a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25311da177e4SLinus Torvalds } 25321da177e4SLinus Torvalds } 25334d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25341da177e4SLinus Torvalds 25354acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2536312b63fbSAl Viro bool want_excl) 25371da177e4SLinus Torvalds { 2538a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25391da177e4SLinus Torvalds if (error) 25401da177e4SLinus Torvalds return error; 25411da177e4SLinus Torvalds 2542acfa4380SAl Viro if (!dir->i_op->create) 25431da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25441da177e4SLinus Torvalds mode &= S_IALLUGO; 25451da177e4SLinus Torvalds mode |= S_IFREG; 25461da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25471da177e4SLinus Torvalds if (error) 25481da177e4SLinus Torvalds return error; 2549312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2550a74574aaSStephen Smalley if (!error) 2551f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25521da177e4SLinus Torvalds return error; 25531da177e4SLinus Torvalds } 25544d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25551da177e4SLinus Torvalds 255673d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25571da177e4SLinus Torvalds { 25583fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25591da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25601da177e4SLinus Torvalds int error; 25611da177e4SLinus Torvalds 2562bcda7652SAl Viro /* O_PATH? */ 2563bcda7652SAl Viro if (!acc_mode) 2564bcda7652SAl Viro return 0; 2565bcda7652SAl Viro 25661da177e4SLinus Torvalds if (!inode) 25671da177e4SLinus Torvalds return -ENOENT; 25681da177e4SLinus Torvalds 2569c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2570c8fe8f30SChristoph Hellwig case S_IFLNK: 25711da177e4SLinus Torvalds return -ELOOP; 2572c8fe8f30SChristoph Hellwig case S_IFDIR: 2573c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25741da177e4SLinus Torvalds return -EISDIR; 2575c8fe8f30SChristoph Hellwig break; 2576c8fe8f30SChristoph Hellwig case S_IFBLK: 2577c8fe8f30SChristoph Hellwig case S_IFCHR: 25783fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25791da177e4SLinus Torvalds return -EACCES; 2580c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2581c8fe8f30SChristoph Hellwig case S_IFIFO: 2582c8fe8f30SChristoph Hellwig case S_IFSOCK: 25831da177e4SLinus Torvalds flag &= ~O_TRUNC; 2584c8fe8f30SChristoph Hellwig break; 25854a3fd211SDave Hansen } 2586b41572e9SDave Hansen 25873fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2588b41572e9SDave Hansen if (error) 2589b41572e9SDave Hansen return error; 25906146f0d5SMimi Zohar 25911da177e4SLinus Torvalds /* 25921da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 25931da177e4SLinus Torvalds */ 25941da177e4SLinus Torvalds if (IS_APPEND(inode)) { 25958737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 25967715b521SAl Viro return -EPERM; 25971da177e4SLinus Torvalds if (flag & O_TRUNC) 25987715b521SAl Viro return -EPERM; 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds 26011da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26022e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26037715b521SAl Viro return -EPERM; 26041da177e4SLinus Torvalds 2605f3c7691eSJ. Bruce Fields return 0; 26067715b521SAl Viro } 26077715b521SAl Viro 2608e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26097715b521SAl Viro { 2610e1181ee6SJeff Layton struct path *path = &filp->f_path; 26117715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26127715b521SAl Viro int error = get_write_access(inode); 26131da177e4SLinus Torvalds if (error) 26147715b521SAl Viro return error; 26151da177e4SLinus Torvalds /* 26161da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26171da177e4SLinus Torvalds */ 2618d7a06983SJeff Layton error = locks_verify_locked(filp); 2619be6d3e56SKentaro Takeda if (!error) 2620ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26211da177e4SLinus Torvalds if (!error) { 26227715b521SAl Viro error = do_truncate(path->dentry, 0, 2623d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2624e1181ee6SJeff Layton filp); 26251da177e4SLinus Torvalds } 26261da177e4SLinus Torvalds put_write_access(inode); 2627acd0c935SMimi Zohar return error; 26281da177e4SLinus Torvalds } 26291da177e4SLinus Torvalds 2630d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2631d57999e1SDave Hansen { 26328a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26338a5e929dSAl Viro flag--; 2634d57999e1SDave Hansen return flag; 2635d57999e1SDave Hansen } 2636d57999e1SDave Hansen 2637d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2638d18e9008SMiklos Szeredi { 2639d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2640d18e9008SMiklos Szeredi if (error) 2641d18e9008SMiklos Szeredi return error; 2642d18e9008SMiklos Szeredi 2643d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2644d18e9008SMiklos Szeredi if (error) 2645d18e9008SMiklos Szeredi return error; 2646d18e9008SMiklos Szeredi 2647d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2648d18e9008SMiklos Szeredi } 2649d18e9008SMiklos Szeredi 26501acf0af9SDavid Howells /* 26511acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26521acf0af9SDavid Howells * dentry. 26531acf0af9SDavid Howells * 26541acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26551acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26561acf0af9SDavid Howells * 26571acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26581acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26591acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26601acf0af9SDavid Howells * 26611acf0af9SDavid Howells * Returns an error code otherwise. 26621acf0af9SDavid Howells */ 26632675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 266430d90494SAl Viro struct path *path, struct file *file, 2665015c3bbcSMiklos Szeredi const struct open_flags *op, 266664894cf8SAl Viro bool got_write, bool need_lookup, 266747237687SAl Viro int *opened) 2668d18e9008SMiklos Szeredi { 2669d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2670d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2671d18e9008SMiklos Szeredi umode_t mode; 2672d18e9008SMiklos Szeredi int error; 2673d18e9008SMiklos Szeredi int acc_mode; 2674d18e9008SMiklos Szeredi int create_error = 0; 2675d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2676116cc022SMiklos Szeredi bool excl; 2677d18e9008SMiklos Szeredi 2678d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2679d18e9008SMiklos Szeredi 2680d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2681d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26822675a4ebSAl Viro error = -ENOENT; 2683d18e9008SMiklos Szeredi goto out; 2684d18e9008SMiklos Szeredi } 2685d18e9008SMiklos Szeredi 268662b259d8SMiklos Szeredi mode = op->mode; 2687d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2688d18e9008SMiklos Szeredi mode &= ~current_umask(); 2689d18e9008SMiklos Szeredi 2690116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2691116cc022SMiklos Szeredi if (excl) 2692d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2693d18e9008SMiklos Szeredi 2694d18e9008SMiklos Szeredi /* 2695d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2696d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2697d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2698d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2699d18e9008SMiklos Szeredi * 2700d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2701d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2702d18e9008SMiklos Szeredi */ 270364894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 270464894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 270564894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2706d18e9008SMiklos Szeredi /* 2707d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2708d18e9008SMiklos Szeredi * back to lookup + open 2709d18e9008SMiklos Szeredi */ 2710d18e9008SMiklos Szeredi goto no_open; 2711d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2712d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 271364894cf8SAl Viro create_error = -EROFS; 2714d18e9008SMiklos Szeredi goto no_open; 2715d18e9008SMiklos Szeredi } else { 2716d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 271764894cf8SAl Viro create_error = -EROFS; 2718d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2719d18e9008SMiklos Szeredi } 2720d18e9008SMiklos Szeredi } 2721d18e9008SMiklos Szeredi 2722d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 272338227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2724d18e9008SMiklos Szeredi if (error) { 2725d18e9008SMiklos Szeredi create_error = error; 2726d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2727d18e9008SMiklos Szeredi goto no_open; 2728d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2729d18e9008SMiklos Szeredi } 2730d18e9008SMiklos Szeredi } 2731d18e9008SMiklos Szeredi 2732d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2733d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2734d18e9008SMiklos Szeredi 273530d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 273630d90494SAl Viro file->f_path.mnt = nd->path.mnt; 273730d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 273847237687SAl Viro opened); 2739d9585277SAl Viro if (error < 0) { 2740d9585277SAl Viro if (create_error && error == -ENOENT) 2741d9585277SAl Viro error = create_error; 2742d18e9008SMiklos Szeredi goto out; 2743d18e9008SMiklos Szeredi } 2744d18e9008SMiklos Szeredi 2745d9585277SAl Viro if (error) { /* returned 1, that is */ 274630d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27472675a4ebSAl Viro error = -EIO; 2748d18e9008SMiklos Szeredi goto out; 2749d18e9008SMiklos Szeredi } 275030d90494SAl Viro if (file->f_path.dentry) { 2751d18e9008SMiklos Szeredi dput(dentry); 275230d90494SAl Viro dentry = file->f_path.dentry; 2753d18e9008SMiklos Szeredi } 275403da633aSAl Viro if (*opened & FILE_CREATED) 275503da633aSAl Viro fsnotify_create(dir, dentry); 275603da633aSAl Viro if (!dentry->d_inode) { 275703da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 275803da633aSAl Viro if (create_error) { 275962b2ce96SSage Weil error = create_error; 276062b2ce96SSage Weil goto out; 276162b2ce96SSage Weil } 276203da633aSAl Viro } else { 276303da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 276403da633aSAl Viro error = -EEXIST; 276503da633aSAl Viro goto out; 276603da633aSAl Viro } 276703da633aSAl Viro } 2768d18e9008SMiklos Szeredi goto looked_up; 2769d18e9008SMiklos Szeredi } 2770d18e9008SMiklos Szeredi 2771d18e9008SMiklos Szeredi /* 2772d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2773d18e9008SMiklos Szeredi * here. 2774d18e9008SMiklos Szeredi */ 277503da633aSAl Viro acc_mode = op->acc_mode; 277603da633aSAl Viro if (*opened & FILE_CREATED) { 277703da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 277803da633aSAl Viro fsnotify_create(dir, dentry); 277903da633aSAl Viro acc_mode = MAY_OPEN; 278003da633aSAl Viro } 27812675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27822675a4ebSAl Viro if (error) 27832675a4ebSAl Viro fput(file); 2784d18e9008SMiklos Szeredi 2785d18e9008SMiklos Szeredi out: 2786d18e9008SMiklos Szeredi dput(dentry); 27872675a4ebSAl Viro return error; 2788d18e9008SMiklos Szeredi 2789d18e9008SMiklos Szeredi no_open: 2790d18e9008SMiklos Szeredi if (need_lookup) { 279172bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2792d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 27932675a4ebSAl Viro return PTR_ERR(dentry); 2794d18e9008SMiklos Szeredi 2795d18e9008SMiklos Szeredi if (create_error) { 2796d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2797d18e9008SMiklos Szeredi 27982675a4ebSAl Viro error = create_error; 2799d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2800d18e9008SMiklos Szeredi if (!dentry->d_inode) 2801d18e9008SMiklos Szeredi goto out; 2802d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2803d18e9008SMiklos Szeredi goto out; 2804d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2805d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2806d18e9008SMiklos Szeredi goto out; 2807d18e9008SMiklos Szeredi } 2808d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2809d18e9008SMiklos Szeredi } 2810d18e9008SMiklos Szeredi } 2811d18e9008SMiklos Szeredi looked_up: 2812d18e9008SMiklos Szeredi path->dentry = dentry; 2813d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28142675a4ebSAl Viro return 1; 2815d18e9008SMiklos Szeredi } 2816d18e9008SMiklos Szeredi 281731e6b01fSNick Piggin /* 28181acf0af9SDavid Howells * Look up and maybe create and open the last component. 2819d58ffd35SMiklos Szeredi * 2820d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2821d58ffd35SMiklos Szeredi * 28221acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28231acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28241acf0af9SDavid Howells * 28251acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28261acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28271acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28281acf0af9SDavid Howells * specified then a negative dentry may be returned. 28291acf0af9SDavid Howells * 28301acf0af9SDavid Howells * An error code is returned otherwise. 28311acf0af9SDavid Howells * 28321acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28331acf0af9SDavid Howells * cleared otherwise prior to returning. 2834d58ffd35SMiklos Szeredi */ 28352675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 283630d90494SAl Viro struct file *file, 2837d58ffd35SMiklos Szeredi const struct open_flags *op, 283864894cf8SAl Viro bool got_write, int *opened) 2839d58ffd35SMiklos Szeredi { 2840d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 284154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2842d58ffd35SMiklos Szeredi struct dentry *dentry; 2843d58ffd35SMiklos Szeredi int error; 284454ef4872SMiklos Szeredi bool need_lookup; 2845d58ffd35SMiklos Szeredi 284647237687SAl Viro *opened &= ~FILE_CREATED; 2847201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2848d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28492675a4ebSAl Viro return PTR_ERR(dentry); 2850d58ffd35SMiklos Szeredi 2851d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2852d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2853d18e9008SMiklos Szeredi goto out_no_open; 2854d18e9008SMiklos Szeredi 2855d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 285664894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 285747237687SAl Viro need_lookup, opened); 2858d18e9008SMiklos Szeredi } 2859d18e9008SMiklos Szeredi 286054ef4872SMiklos Szeredi if (need_lookup) { 286154ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 286254ef4872SMiklos Szeredi 286372bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 286454ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28652675a4ebSAl Viro return PTR_ERR(dentry); 286654ef4872SMiklos Szeredi } 286754ef4872SMiklos Szeredi 2868d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2869d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2870d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2871d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2872d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2873d58ffd35SMiklos Szeredi /* 2874d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2875d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2876d58ffd35SMiklos Szeredi * the time when the file is created and when 2877d58ffd35SMiklos Szeredi * a permanent write count is taken through 2878015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2879d58ffd35SMiklos Szeredi */ 288064894cf8SAl Viro if (!got_write) { 288164894cf8SAl Viro error = -EROFS; 2882d58ffd35SMiklos Szeredi goto out_dput; 288364894cf8SAl Viro } 288447237687SAl Viro *opened |= FILE_CREATED; 2885d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2886d58ffd35SMiklos Szeredi if (error) 2887d58ffd35SMiklos Szeredi goto out_dput; 2888312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2889312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2890d58ffd35SMiklos Szeredi if (error) 2891d58ffd35SMiklos Szeredi goto out_dput; 2892d58ffd35SMiklos Szeredi } 2893d18e9008SMiklos Szeredi out_no_open: 2894d58ffd35SMiklos Szeredi path->dentry = dentry; 2895d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 28962675a4ebSAl Viro return 1; 2897d58ffd35SMiklos Szeredi 2898d58ffd35SMiklos Szeredi out_dput: 2899d58ffd35SMiklos Szeredi dput(dentry); 29002675a4ebSAl Viro return error; 2901d58ffd35SMiklos Szeredi } 2902d58ffd35SMiklos Szeredi 2903d58ffd35SMiklos Szeredi /* 2904fe2d35ffSAl Viro * Handle the last step of open() 290531e6b01fSNick Piggin */ 29062675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 290730d90494SAl Viro struct file *file, const struct open_flags *op, 2908669abf4eSJeff Layton int *opened, struct filename *name) 2909fb1cc555SAl Viro { 2910a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2911ca344a89SAl Viro int open_flag = op->open_flag; 291277d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 291364894cf8SAl Viro bool got_write = false; 2914bcda7652SAl Viro int acc_mode = op->acc_mode; 2915a1eb3315SMiklos Szeredi struct inode *inode; 291677d660a8SMiklos Szeredi bool symlink_ok = false; 291716b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 291816b1c1cdSMiklos Szeredi bool retried = false; 291916c2cd71SAl Viro int error; 2920fb1cc555SAl Viro 2921c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2922c3e380b0SAl Viro nd->flags |= op->intent; 2923c3e380b0SAl Viro 2924bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2925fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2926fe2d35ffSAl Viro if (error) 29272675a4ebSAl Viro return error; 2928e83db167SMiklos Szeredi goto finish_open; 29291f36f774SAl Viro } 2930a2c36b45SAl Viro 2931ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2932fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2933fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2934bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 293577d660a8SMiklos Szeredi symlink_ok = true; 2936fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2937e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 293871574865SMiklos Szeredi if (likely(!error)) 293971574865SMiklos Szeredi goto finish_lookup; 294071574865SMiklos Szeredi 2941ce57dfc1SAl Viro if (error < 0) 29422675a4ebSAl Viro goto out; 2943a1eb3315SMiklos Szeredi 294437d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2945b6183df7SMiklos Szeredi } else { 2946fe2d35ffSAl Viro /* create side of things */ 2947a3fbbde7SAl Viro /* 2948b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2949b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2950b6183df7SMiklos Szeredi * about to look up 2951a3fbbde7SAl Viro */ 29529f1fafeeSAl Viro error = complete_walk(nd); 29539f1fafeeSAl Viro if (error) 29542675a4ebSAl Viro return error; 2955fe2d35ffSAl Viro 295633e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 295716c2cd71SAl Viro error = -EISDIR; 29581f36f774SAl Viro /* trailing slashes? */ 295931e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29602675a4ebSAl Viro goto out; 2961b6183df7SMiklos Szeredi } 29621f36f774SAl Viro 296316b1c1cdSMiklos Szeredi retry_lookup: 296464894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 296564894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 296664894cf8SAl Viro if (!error) 296764894cf8SAl Viro got_write = true; 296864894cf8SAl Viro /* 296964894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 297064894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 297164894cf8SAl Viro * dropping this one anyway. 297264894cf8SAl Viro */ 297364894cf8SAl Viro } 2974a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 297564894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2976fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2977fb1cc555SAl Viro 29782675a4ebSAl Viro if (error <= 0) { 29792675a4ebSAl Viro if (error) 2980d58ffd35SMiklos Szeredi goto out; 29816c0d46c4SAl Viro 298247237687SAl Viro if ((*opened & FILE_CREATED) || 2983496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 298477d660a8SMiklos Szeredi will_truncate = false; 2985d18e9008SMiklos Szeredi 2986adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 2987d18e9008SMiklos Szeredi goto opened; 2988d18e9008SMiklos Szeredi } 2989d18e9008SMiklos Szeredi 299047237687SAl Viro if (*opened & FILE_CREATED) { 29919b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 2992ca344a89SAl Viro open_flag &= ~O_TRUNC; 299377d660a8SMiklos Szeredi will_truncate = false; 2994bcda7652SAl Viro acc_mode = MAY_OPEN; 2995d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 2996e83db167SMiklos Szeredi goto finish_open_created; 2997fb1cc555SAl Viro } 2998fb1cc555SAl Viro 2999fb1cc555SAl Viro /* 30003134f37eSJeff Layton * create/update audit record if it already exists. 3001fb1cc555SAl Viro */ 3002b18825a7SDavid Howells if (d_is_positive(path->dentry)) 3003adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 3004fb1cc555SAl Viro 3005d18e9008SMiklos Szeredi /* 3006d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3007d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3008d18e9008SMiklos Szeredi * necessary...) 3009d18e9008SMiklos Szeredi */ 301064894cf8SAl Viro if (got_write) { 3011d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 301264894cf8SAl Viro got_write = false; 3013d18e9008SMiklos Szeredi } 3014d18e9008SMiklos Szeredi 3015fb1cc555SAl Viro error = -EEXIST; 3016f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3017fb1cc555SAl Viro goto exit_dput; 3018fb1cc555SAl Viro 30199875cf80SDavid Howells error = follow_managed(path, nd->flags); 30209875cf80SDavid Howells if (error < 0) 3021fb1cc555SAl Viro goto exit_dput; 3022fb1cc555SAl Viro 3023a3fbbde7SAl Viro if (error) 3024a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3025a3fbbde7SAl Viro 3026decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3027decf3400SMiklos Szeredi inode = path->dentry->d_inode; 30285f5daac1SMiklos Szeredi finish_lookup: 30295f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 3030fb1cc555SAl Viro error = -ENOENT; 303122213318SAl Viro if (!inode || d_is_negative(path->dentry)) { 303254c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 30332675a4ebSAl Viro goto out; 303454c33e7fSMiklos Szeredi } 30359e67f361SAl Viro 3036b18825a7SDavid Howells if (should_follow_link(path->dentry, !symlink_ok)) { 3037d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3038d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 3039d45ea867SMiklos Szeredi error = -ECHILD; 30402675a4ebSAl Viro goto out; 3041d45ea867SMiklos Szeredi } 3042d45ea867SMiklos Szeredi } 3043d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 30442675a4ebSAl Viro return 1; 3045d45ea867SMiklos Szeredi } 3046fb1cc555SAl Viro 304716b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 3048fb1cc555SAl Viro path_to_nameidata(path, nd); 304916b1c1cdSMiklos Szeredi } else { 305016b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 305116b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 305216b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 305316b1c1cdSMiklos Szeredi 305416b1c1cdSMiklos Szeredi } 3055decf3400SMiklos Szeredi nd->inode = inode; 3056a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3057bc77daa7SAl Viro finish_open: 3058a3fbbde7SAl Viro error = complete_walk(nd); 305916b1c1cdSMiklos Szeredi if (error) { 306016b1c1cdSMiklos Szeredi path_put(&save_parent); 30612675a4ebSAl Viro return error; 306216b1c1cdSMiklos Szeredi } 3063bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3064fb1cc555SAl Viro error = -EISDIR; 306544b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 30662675a4ebSAl Viro goto out; 3067af2f5542SMiklos Szeredi error = -ENOTDIR; 306844b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 30692675a4ebSAl Viro goto out; 30706c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 307177d660a8SMiklos Szeredi will_truncate = false; 30726c0d46c4SAl Viro 30730f9d1a10SAl Viro if (will_truncate) { 30740f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30750f9d1a10SAl Viro if (error) 30762675a4ebSAl Viro goto out; 307764894cf8SAl Viro got_write = true; 30780f9d1a10SAl Viro } 3079e83db167SMiklos Szeredi finish_open_created: 3080bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3081ca344a89SAl Viro if (error) 30822675a4ebSAl Viro goto out; 30834aa7c634SMiklos Szeredi 30844aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 30854aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 30864aa7c634SMiklos Szeredi if (!error) { 30874aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 30884aa7c634SMiklos Szeredi } else { 308930d90494SAl Viro if (error == -EOPENSTALE) 3090f60dc3dbSMiklos Szeredi goto stale_open; 3091015c3bbcSMiklos Szeredi goto out; 3092f60dc3dbSMiklos Szeredi } 3093a8277b9bSMiklos Szeredi opened: 30942675a4ebSAl Viro error = open_check_o_direct(file); 3095015c3bbcSMiklos Szeredi if (error) 3096015c3bbcSMiklos Szeredi goto exit_fput; 30973034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3098aa4caadbSMiklos Szeredi if (error) 3099aa4caadbSMiklos Szeredi goto exit_fput; 3100aa4caadbSMiklos Szeredi 31010f9d1a10SAl Viro if (will_truncate) { 31022675a4ebSAl Viro error = handle_truncate(file); 3103aa4caadbSMiklos Szeredi if (error) 3104aa4caadbSMiklos Szeredi goto exit_fput; 31050f9d1a10SAl Viro } 3106ca344a89SAl Viro out: 310764894cf8SAl Viro if (got_write) 31080f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 310916b1c1cdSMiklos Szeredi path_put(&save_parent); 3110e276ae67SMiklos Szeredi terminate_walk(nd); 31112675a4ebSAl Viro return error; 3112fb1cc555SAl Viro 3113fb1cc555SAl Viro exit_dput: 3114fb1cc555SAl Viro path_put_conditional(path, nd); 3115ca344a89SAl Viro goto out; 3116015c3bbcSMiklos Szeredi exit_fput: 31172675a4ebSAl Viro fput(file); 31182675a4ebSAl Viro goto out; 3119015c3bbcSMiklos Szeredi 3120f60dc3dbSMiklos Szeredi stale_open: 3121f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3122f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3123f60dc3dbSMiklos Szeredi goto out; 3124f60dc3dbSMiklos Szeredi 3125f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3126f60dc3dbSMiklos Szeredi path_put(&nd->path); 3127f60dc3dbSMiklos Szeredi nd->path = save_parent; 3128f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3129f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3130f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 313164894cf8SAl Viro if (got_write) { 3132f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 313364894cf8SAl Viro got_write = false; 3134f60dc3dbSMiklos Szeredi } 3135f60dc3dbSMiklos Szeredi retried = true; 3136f60dc3dbSMiklos Szeredi goto retry_lookup; 3137fb1cc555SAl Viro } 3138fb1cc555SAl Viro 313960545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 314060545d0dSAl Viro struct nameidata *nd, int flags, 314160545d0dSAl Viro const struct open_flags *op, 314260545d0dSAl Viro struct file *file, int *opened) 314360545d0dSAl Viro { 314460545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 314560545d0dSAl Viro struct dentry *dentry, *child; 314660545d0dSAl Viro struct inode *dir; 314760545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 314860545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 314960545d0dSAl Viro if (unlikely(error)) 315060545d0dSAl Viro return error; 315160545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 315260545d0dSAl Viro if (unlikely(error)) 315360545d0dSAl Viro goto out; 315460545d0dSAl Viro /* we want directory to be writable */ 315560545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 315660545d0dSAl Viro if (error) 315760545d0dSAl Viro goto out2; 315860545d0dSAl Viro dentry = nd->path.dentry; 315960545d0dSAl Viro dir = dentry->d_inode; 316060545d0dSAl Viro if (!dir->i_op->tmpfile) { 316160545d0dSAl Viro error = -EOPNOTSUPP; 316260545d0dSAl Viro goto out2; 316360545d0dSAl Viro } 316460545d0dSAl Viro child = d_alloc(dentry, &name); 316560545d0dSAl Viro if (unlikely(!child)) { 316660545d0dSAl Viro error = -ENOMEM; 316760545d0dSAl Viro goto out2; 316860545d0dSAl Viro } 316960545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 317060545d0dSAl Viro nd->flags |= op->intent; 317160545d0dSAl Viro dput(nd->path.dentry); 317260545d0dSAl Viro nd->path.dentry = child; 317360545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 317460545d0dSAl Viro if (error) 317560545d0dSAl Viro goto out2; 317660545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 317769a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 317869a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 317960545d0dSAl Viro if (error) 318060545d0dSAl Viro goto out2; 318160545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 318260545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 318360545d0dSAl Viro if (error) 318460545d0dSAl Viro goto out2; 318560545d0dSAl Viro error = open_check_o_direct(file); 3186f4e0c30cSAl Viro if (error) { 318760545d0dSAl Viro fput(file); 3188f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3189f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3190f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3191f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3192f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3193f4e0c30cSAl Viro } 319460545d0dSAl Viro out2: 319560545d0dSAl Viro mnt_drop_write(nd->path.mnt); 319660545d0dSAl Viro out: 319760545d0dSAl Viro path_put(&nd->path); 319860545d0dSAl Viro return error; 319960545d0dSAl Viro } 320060545d0dSAl Viro 3201669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 320273d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32031da177e4SLinus Torvalds { 320430d90494SAl Viro struct file *file; 32059850c056SAl Viro struct path path; 320647237687SAl Viro int opened = 0; 320713aab428SAl Viro int error; 320831e6b01fSNick Piggin 320930d90494SAl Viro file = get_empty_filp(); 32101afc99beSAl Viro if (IS_ERR(file)) 32111afc99beSAl Viro return file; 321231e6b01fSNick Piggin 321330d90494SAl Viro file->f_flags = op->open_flag; 321431e6b01fSNick Piggin 3215bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 321660545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 321760545d0dSAl Viro goto out; 321860545d0dSAl Viro } 321960545d0dSAl Viro 3220980f3ea2SAl Viro error = path_init(dfd, pathname->name, flags, nd); 322131e6b01fSNick Piggin if (unlikely(error)) 32222675a4ebSAl Viro goto out; 32231da177e4SLinus Torvalds 32242675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 32252675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 32267b9337aaSNick Piggin struct path link = path; 3227def4af30SAl Viro void *cookie; 3228574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 322973d049a4SAl Viro path_put_conditional(&path, nd); 323073d049a4SAl Viro path_put(&nd->path); 32312675a4ebSAl Viro error = -ELOOP; 323240b39136SAl Viro break; 323340b39136SAl Viro } 3234800179c9SKees Cook error = may_follow_link(&link, nd); 3235800179c9SKees Cook if (unlikely(error)) 3236800179c9SKees Cook break; 323773d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 323873d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3239574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3240c3e380b0SAl Viro if (unlikely(error)) 32412675a4ebSAl Viro break; 32422675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3243574197e0SAl Viro put_link(nd, &link, cookie); 3244806b681cSAl Viro } 324510fa8e62SAl Viro out: 3246893b7775SAl Viro path_cleanup(nd); 32472675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32482675a4ebSAl Viro BUG_ON(!error); 324930d90494SAl Viro put_filp(file); 3250015c3bbcSMiklos Szeredi } 32512675a4ebSAl Viro if (unlikely(error)) { 32522675a4ebSAl Viro if (error == -EOPENSTALE) { 32532675a4ebSAl Viro if (flags & LOOKUP_RCU) 32542675a4ebSAl Viro error = -ECHILD; 32552675a4ebSAl Viro else 32562675a4ebSAl Viro error = -ESTALE; 32572675a4ebSAl Viro } 32582675a4ebSAl Viro file = ERR_PTR(error); 32592675a4ebSAl Viro } 32602675a4ebSAl Viro return file; 3261de459215SKirill Korotaev } 32621da177e4SLinus Torvalds 3263669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3264f9652e10SAl Viro const struct open_flags *op) 326513aab428SAl Viro { 326673d049a4SAl Viro struct nameidata nd; 3267f9652e10SAl Viro int flags = op->lookup_flags; 326813aab428SAl Viro struct file *filp; 326913aab428SAl Viro 327073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 327113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 327273d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 327313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 327473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 327513aab428SAl Viro return filp; 327613aab428SAl Viro } 327713aab428SAl Viro 327873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3279f9652e10SAl Viro const char *name, const struct open_flags *op) 328073d049a4SAl Viro { 328173d049a4SAl Viro struct nameidata nd; 328273d049a4SAl Viro struct file *file; 3283669abf4eSJeff Layton struct filename filename = { .name = name }; 3284f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 328573d049a4SAl Viro 328673d049a4SAl Viro nd.root.mnt = mnt; 328773d049a4SAl Viro nd.root.dentry = dentry; 328873d049a4SAl Viro 3289b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 329073d049a4SAl Viro return ERR_PTR(-ELOOP); 329173d049a4SAl Viro 3292669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); 329373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3294669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags); 329573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3296669abf4eSJeff Layton file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); 329773d049a4SAl Viro return file; 329873d049a4SAl Viro } 329973d049a4SAl Viro 3300fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33011ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33021da177e4SLinus Torvalds { 3303c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3304ed75e95dSAl Viro struct nameidata nd; 3305c30dabfeSJan Kara int err2; 33061ac12b4bSJeff Layton int error; 33071ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33081ac12b4bSJeff Layton 33091ac12b4bSJeff Layton /* 33101ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33111ac12b4bSJeff Layton * other flags passed in are ignored! 33121ac12b4bSJeff Layton */ 33131ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33141ac12b4bSJeff Layton 3315fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3316ed75e95dSAl Viro if (error) 3317ed75e95dSAl Viro return ERR_PTR(error); 33181da177e4SLinus Torvalds 3319c663e5d8SChristoph Hellwig /* 3320c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3321c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3322c663e5d8SChristoph Hellwig */ 3323ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3324ed75e95dSAl Viro goto out; 3325ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3326ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3327c663e5d8SChristoph Hellwig 3328c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3329c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3330c663e5d8SChristoph Hellwig /* 3331c663e5d8SChristoph Hellwig * Do the final lookup. 3332c663e5d8SChristoph Hellwig */ 3333ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3334ed75e95dSAl Viro dentry = lookup_hash(&nd); 33351da177e4SLinus Torvalds if (IS_ERR(dentry)) 3336a8104a9fSAl Viro goto unlock; 3337c663e5d8SChristoph Hellwig 3338a8104a9fSAl Viro error = -EEXIST; 3339b18825a7SDavid Howells if (d_is_positive(dentry)) 3340a8104a9fSAl Viro goto fail; 3341b18825a7SDavid Howells 3342c663e5d8SChristoph Hellwig /* 3343c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3344c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3345c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3346c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3347c663e5d8SChristoph Hellwig */ 3348ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3349a8104a9fSAl Viro error = -ENOENT; 3350ed75e95dSAl Viro goto fail; 3351e9baf6e5SAl Viro } 3352c30dabfeSJan Kara if (unlikely(err2)) { 3353c30dabfeSJan Kara error = err2; 3354a8104a9fSAl Viro goto fail; 3355c30dabfeSJan Kara } 3356ed75e95dSAl Viro *path = nd.path; 3357e9baf6e5SAl Viro return dentry; 33581da177e4SLinus Torvalds fail: 3359a8104a9fSAl Viro dput(dentry); 3360a8104a9fSAl Viro dentry = ERR_PTR(error); 3361a8104a9fSAl Viro unlock: 3362dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3363c30dabfeSJan Kara if (!err2) 3364c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3365ed75e95dSAl Viro out: 3366dae6ad8fSAl Viro path_put(&nd.path); 3367ed75e95dSAl Viro return dentry; 3368dae6ad8fSAl Viro } 3369fa14a0b8SAl Viro 3370fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3371fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3372fa14a0b8SAl Viro { 3373fa14a0b8SAl Viro struct filename filename = {.name = pathname}; 3374fa14a0b8SAl Viro return filename_create(dfd, &filename, path, lookup_flags); 3375fa14a0b8SAl Viro } 3376dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3377dae6ad8fSAl Viro 3378921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3379921a1650SAl Viro { 3380921a1650SAl Viro dput(dentry); 3381921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3382a8104a9fSAl Viro mnt_drop_write(path->mnt); 3383921a1650SAl Viro path_put(path); 3384921a1650SAl Viro } 3385921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3386921a1650SAl Viro 33871ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 33881ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3389dae6ad8fSAl Viro { 339091a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3391dae6ad8fSAl Viro struct dentry *res; 3392dae6ad8fSAl Viro if (IS_ERR(tmp)) 3393dae6ad8fSAl Viro return ERR_CAST(tmp); 3394fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3395dae6ad8fSAl Viro putname(tmp); 3396dae6ad8fSAl Viro return res; 3397dae6ad8fSAl Viro } 3398dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3399dae6ad8fSAl Viro 34001a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34011da177e4SLinus Torvalds { 3402a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34031da177e4SLinus Torvalds 34041da177e4SLinus Torvalds if (error) 34051da177e4SLinus Torvalds return error; 34061da177e4SLinus Torvalds 3407975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34081da177e4SLinus Torvalds return -EPERM; 34091da177e4SLinus Torvalds 3410acfa4380SAl Viro if (!dir->i_op->mknod) 34111da177e4SLinus Torvalds return -EPERM; 34121da177e4SLinus Torvalds 341308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 341408ce5f16SSerge E. Hallyn if (error) 341508ce5f16SSerge E. Hallyn return error; 341608ce5f16SSerge E. Hallyn 34171da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34181da177e4SLinus Torvalds if (error) 34191da177e4SLinus Torvalds return error; 34201da177e4SLinus Torvalds 34211da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3422a74574aaSStephen Smalley if (!error) 3423f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34241da177e4SLinus Torvalds return error; 34251da177e4SLinus Torvalds } 34264d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34271da177e4SLinus Torvalds 3428f69aac00SAl Viro static int may_mknod(umode_t mode) 3429463c3197SDave Hansen { 3430463c3197SDave Hansen switch (mode & S_IFMT) { 3431463c3197SDave Hansen case S_IFREG: 3432463c3197SDave Hansen case S_IFCHR: 3433463c3197SDave Hansen case S_IFBLK: 3434463c3197SDave Hansen case S_IFIFO: 3435463c3197SDave Hansen case S_IFSOCK: 3436463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3437463c3197SDave Hansen return 0; 3438463c3197SDave Hansen case S_IFDIR: 3439463c3197SDave Hansen return -EPERM; 3440463c3197SDave Hansen default: 3441463c3197SDave Hansen return -EINVAL; 3442463c3197SDave Hansen } 3443463c3197SDave Hansen } 3444463c3197SDave Hansen 34458208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34462e4d0924SHeiko Carstens unsigned, dev) 34471da177e4SLinus Torvalds { 34481da177e4SLinus Torvalds struct dentry *dentry; 3449dae6ad8fSAl Viro struct path path; 3450dae6ad8fSAl Viro int error; 3451972567f1SJeff Layton unsigned int lookup_flags = 0; 34521da177e4SLinus Torvalds 34538e4bfca1SAl Viro error = may_mknod(mode); 34548e4bfca1SAl Viro if (error) 34558e4bfca1SAl Viro return error; 3456972567f1SJeff Layton retry: 3457972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3458dae6ad8fSAl Viro if (IS_ERR(dentry)) 3459dae6ad8fSAl Viro return PTR_ERR(dentry); 34602ad94ae6SAl Viro 3461dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3462ce3b0f8dSAl Viro mode &= ~current_umask(); 3463dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3464be6d3e56SKentaro Takeda if (error) 3465a8104a9fSAl Viro goto out; 34661da177e4SLinus Torvalds switch (mode & S_IFMT) { 34671da177e4SLinus Torvalds case 0: case S_IFREG: 3468312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34691da177e4SLinus Torvalds break; 34701da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3471dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34721da177e4SLinus Torvalds new_decode_dev(dev)); 34731da177e4SLinus Torvalds break; 34741da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3475dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34761da177e4SLinus Torvalds break; 34771da177e4SLinus Torvalds } 3478a8104a9fSAl Viro out: 3479921a1650SAl Viro done_path_create(&path, dentry); 3480972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3481972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3482972567f1SJeff Layton goto retry; 3483972567f1SJeff Layton } 34841da177e4SLinus Torvalds return error; 34851da177e4SLinus Torvalds } 34861da177e4SLinus Torvalds 34878208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 34885590ff0dSUlrich Drepper { 34895590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 34905590ff0dSUlrich Drepper } 34915590ff0dSUlrich Drepper 349218bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 34931da177e4SLinus Torvalds { 3494a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34958de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 34961da177e4SLinus Torvalds 34971da177e4SLinus Torvalds if (error) 34981da177e4SLinus Torvalds return error; 34991da177e4SLinus Torvalds 3500acfa4380SAl Viro if (!dir->i_op->mkdir) 35011da177e4SLinus Torvalds return -EPERM; 35021da177e4SLinus Torvalds 35031da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35041da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35051da177e4SLinus Torvalds if (error) 35061da177e4SLinus Torvalds return error; 35071da177e4SLinus Torvalds 35088de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35098de52778SAl Viro return -EMLINK; 35108de52778SAl Viro 35111da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3512a74574aaSStephen Smalley if (!error) 3513f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35141da177e4SLinus Torvalds return error; 35151da177e4SLinus Torvalds } 35164d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35171da177e4SLinus Torvalds 3518a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35191da177e4SLinus Torvalds { 35206902d925SDave Hansen struct dentry *dentry; 3521dae6ad8fSAl Viro struct path path; 3522dae6ad8fSAl Viro int error; 3523b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35241da177e4SLinus Torvalds 3525b76d8b82SJeff Layton retry: 3526b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35276902d925SDave Hansen if (IS_ERR(dentry)) 3528dae6ad8fSAl Viro return PTR_ERR(dentry); 35296902d925SDave Hansen 3530dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3531ce3b0f8dSAl Viro mode &= ~current_umask(); 3532dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3533a8104a9fSAl Viro if (!error) 3534dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3535921a1650SAl Viro done_path_create(&path, dentry); 3536b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3537b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3538b76d8b82SJeff Layton goto retry; 3539b76d8b82SJeff Layton } 35401da177e4SLinus Torvalds return error; 35411da177e4SLinus Torvalds } 35421da177e4SLinus Torvalds 3543a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35445590ff0dSUlrich Drepper { 35455590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35465590ff0dSUlrich Drepper } 35475590ff0dSUlrich Drepper 35481da177e4SLinus Torvalds /* 3549a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3550c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3551a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3552a71905f0SSage Weil * then we drop the dentry now. 35531da177e4SLinus Torvalds * 35541da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35551da177e4SLinus Torvalds * do a 35561da177e4SLinus Torvalds * 35571da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35581da177e4SLinus Torvalds * return -EBUSY; 35591da177e4SLinus Torvalds * 35601da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35611da177e4SLinus Torvalds * that is still in use by something else.. 35621da177e4SLinus Torvalds */ 35631da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35641da177e4SLinus Torvalds { 35651da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35661da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 356798474236SWaiman Long if (dentry->d_lockref.count == 1) 35681da177e4SLinus Torvalds __d_drop(dentry); 35691da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35701da177e4SLinus Torvalds } 35714d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 35721da177e4SLinus Torvalds 35731da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35741da177e4SLinus Torvalds { 35751da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35761da177e4SLinus Torvalds 35771da177e4SLinus Torvalds if (error) 35781da177e4SLinus Torvalds return error; 35791da177e4SLinus Torvalds 3580acfa4380SAl Viro if (!dir->i_op->rmdir) 35811da177e4SLinus Torvalds return -EPERM; 35821da177e4SLinus Torvalds 35831d2ef590SAl Viro dget(dentry); 35841b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3585912dbc15SSage Weil 35861da177e4SLinus Torvalds error = -EBUSY; 35877af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3588912dbc15SSage Weil goto out; 3589912dbc15SSage Weil 35901da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3591912dbc15SSage Weil if (error) 3592912dbc15SSage Weil goto out; 3593912dbc15SSage Weil 35943cebde24SSage Weil shrink_dcache_parent(dentry); 35951da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3596912dbc15SSage Weil if (error) 3597912dbc15SSage Weil goto out; 3598912dbc15SSage Weil 35991da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3600d83c49f3SAl Viro dont_mount(dentry); 36018ed936b5SEric W. Biederman detach_mounts(dentry); 36021da177e4SLinus Torvalds 3603912dbc15SSage Weil out: 3604912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36051d2ef590SAl Viro dput(dentry); 3606912dbc15SSage Weil if (!error) 3607912dbc15SSage Weil d_delete(dentry); 36081da177e4SLinus Torvalds return error; 36091da177e4SLinus Torvalds } 36104d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36111da177e4SLinus Torvalds 36125590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36131da177e4SLinus Torvalds { 36141da177e4SLinus Torvalds int error = 0; 361591a27b2aSJeff Layton struct filename *name; 36161da177e4SLinus Torvalds struct dentry *dentry; 36171da177e4SLinus Torvalds struct nameidata nd; 3618c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3619c6ee9206SJeff Layton retry: 3620c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 362191a27b2aSJeff Layton if (IS_ERR(name)) 362291a27b2aSJeff Layton return PTR_ERR(name); 36231da177e4SLinus Torvalds 36241da177e4SLinus Torvalds switch(nd.last_type) { 36251da177e4SLinus Torvalds case LAST_DOTDOT: 36261da177e4SLinus Torvalds error = -ENOTEMPTY; 36271da177e4SLinus Torvalds goto exit1; 36281da177e4SLinus Torvalds case LAST_DOT: 36291da177e4SLinus Torvalds error = -EINVAL; 36301da177e4SLinus Torvalds goto exit1; 36311da177e4SLinus Torvalds case LAST_ROOT: 36321da177e4SLinus Torvalds error = -EBUSY; 36331da177e4SLinus Torvalds goto exit1; 36341da177e4SLinus Torvalds } 36350612d9fbSOGAWA Hirofumi 36360612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3637c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3638c30dabfeSJan Kara if (error) 3639c30dabfeSJan Kara goto exit1; 36400612d9fbSOGAWA Hirofumi 36414ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 364249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36431da177e4SLinus Torvalds error = PTR_ERR(dentry); 36446902d925SDave Hansen if (IS_ERR(dentry)) 36456902d925SDave Hansen goto exit2; 3646e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3647e6bc45d6STheodore Ts'o error = -ENOENT; 3648e6bc45d6STheodore Ts'o goto exit3; 3649e6bc45d6STheodore Ts'o } 3650be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3651be6d3e56SKentaro Takeda if (error) 3652c30dabfeSJan Kara goto exit3; 36534ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 36540622753bSDave Hansen exit3: 36551da177e4SLinus Torvalds dput(dentry); 36566902d925SDave Hansen exit2: 36574ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3658c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 36591da177e4SLinus Torvalds exit1: 36601d957f9bSJan Blunck path_put(&nd.path); 36611da177e4SLinus Torvalds putname(name); 3662c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3663c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3664c6ee9206SJeff Layton goto retry; 3665c6ee9206SJeff Layton } 36661da177e4SLinus Torvalds return error; 36671da177e4SLinus Torvalds } 36681da177e4SLinus Torvalds 36693cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36705590ff0dSUlrich Drepper { 36715590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36725590ff0dSUlrich Drepper } 36735590ff0dSUlrich Drepper 3674b21996e3SJ. Bruce Fields /** 3675b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3676b21996e3SJ. Bruce Fields * @dir: parent directory 3677b21996e3SJ. Bruce Fields * @dentry: victim 3678b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3679b21996e3SJ. Bruce Fields * 3680b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3681b21996e3SJ. Bruce Fields * 3682b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3683b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3684b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3685b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3686b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3687b21996e3SJ. Bruce Fields * 3688b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3689b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3690b21996e3SJ. Bruce Fields * to be NFS exported. 3691b21996e3SJ. Bruce Fields */ 3692b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 36931da177e4SLinus Torvalds { 36949accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 36951da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 36961da177e4SLinus Torvalds 36971da177e4SLinus Torvalds if (error) 36981da177e4SLinus Torvalds return error; 36991da177e4SLinus Torvalds 3700acfa4380SAl Viro if (!dir->i_op->unlink) 37011da177e4SLinus Torvalds return -EPERM; 37021da177e4SLinus Torvalds 37039accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37048ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37051da177e4SLinus Torvalds error = -EBUSY; 37061da177e4SLinus Torvalds else { 37071da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3708bec1052eSAl Viro if (!error) { 37095a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37105a14696cSJ. Bruce Fields if (error) 3711b21996e3SJ. Bruce Fields goto out; 37121da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37138ed936b5SEric W. Biederman if (!error) { 3714d83c49f3SAl Viro dont_mount(dentry); 37158ed936b5SEric W. Biederman detach_mounts(dentry); 37168ed936b5SEric W. Biederman } 3717bec1052eSAl Viro } 37181da177e4SLinus Torvalds } 3719b21996e3SJ. Bruce Fields out: 37209accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37211da177e4SLinus Torvalds 37221da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37231da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37249accbb97SJ. Bruce Fields fsnotify_link_count(target); 37251da177e4SLinus Torvalds d_delete(dentry); 37261da177e4SLinus Torvalds } 37270eeca283SRobert Love 37281da177e4SLinus Torvalds return error; 37291da177e4SLinus Torvalds } 37304d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37311da177e4SLinus Torvalds 37321da177e4SLinus Torvalds /* 37331da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37341b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37351da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37361da177e4SLinus Torvalds * while waiting on the I/O. 37371da177e4SLinus Torvalds */ 37385590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37391da177e4SLinus Torvalds { 37402ad94ae6SAl Viro int error; 374191a27b2aSJeff Layton struct filename *name; 37421da177e4SLinus Torvalds struct dentry *dentry; 37431da177e4SLinus Torvalds struct nameidata nd; 37441da177e4SLinus Torvalds struct inode *inode = NULL; 3745b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37465d18f813SJeff Layton unsigned int lookup_flags = 0; 37475d18f813SJeff Layton retry: 37485d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 374991a27b2aSJeff Layton if (IS_ERR(name)) 375091a27b2aSJeff Layton return PTR_ERR(name); 37512ad94ae6SAl Viro 37521da177e4SLinus Torvalds error = -EISDIR; 37531da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 37541da177e4SLinus Torvalds goto exit1; 37550612d9fbSOGAWA Hirofumi 37560612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3757c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3758c30dabfeSJan Kara if (error) 3759c30dabfeSJan Kara goto exit1; 3760b21996e3SJ. Bruce Fields retry_deleg: 37614ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 376249705b77SChristoph Hellwig dentry = lookup_hash(&nd); 37631da177e4SLinus Torvalds error = PTR_ERR(dentry); 37641da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37651da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 376650338b88STörök Edwin if (nd.last.name[nd.last.len]) 376750338b88STörök Edwin goto slashes; 37681da177e4SLinus Torvalds inode = dentry->d_inode; 3769b18825a7SDavid Howells if (d_is_negative(dentry)) 3770e6bc45d6STheodore Ts'o goto slashes; 37717de9c6eeSAl Viro ihold(inode); 3772be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3773be6d3e56SKentaro Takeda if (error) 3774c30dabfeSJan Kara goto exit2; 3775b21996e3SJ. Bruce Fields error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); 37761da177e4SLinus Torvalds exit2: 37771da177e4SLinus Torvalds dput(dentry); 37781da177e4SLinus Torvalds } 37794ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 37801da177e4SLinus Torvalds if (inode) 37811da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3782b21996e3SJ. Bruce Fields inode = NULL; 3783b21996e3SJ. Bruce Fields if (delegated_inode) { 37845a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3785b21996e3SJ. Bruce Fields if (!error) 3786b21996e3SJ. Bruce Fields goto retry_deleg; 3787b21996e3SJ. Bruce Fields } 3788c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 37891da177e4SLinus Torvalds exit1: 37901d957f9bSJan Blunck path_put(&nd.path); 37911da177e4SLinus Torvalds putname(name); 37925d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 37935d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 37945d18f813SJeff Layton inode = NULL; 37955d18f813SJeff Layton goto retry; 37965d18f813SJeff Layton } 37971da177e4SLinus Torvalds return error; 37981da177e4SLinus Torvalds 37991da177e4SLinus Torvalds slashes: 3800b18825a7SDavid Howells if (d_is_negative(dentry)) 3801b18825a7SDavid Howells error = -ENOENT; 380244b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3803b18825a7SDavid Howells error = -EISDIR; 3804b18825a7SDavid Howells else 3805b18825a7SDavid Howells error = -ENOTDIR; 38061da177e4SLinus Torvalds goto exit2; 38071da177e4SLinus Torvalds } 38081da177e4SLinus Torvalds 38092e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38105590ff0dSUlrich Drepper { 38115590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38125590ff0dSUlrich Drepper return -EINVAL; 38135590ff0dSUlrich Drepper 38145590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38155590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38165590ff0dSUlrich Drepper 38175590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38185590ff0dSUlrich Drepper } 38195590ff0dSUlrich Drepper 38203480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38215590ff0dSUlrich Drepper { 38225590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38235590ff0dSUlrich Drepper } 38245590ff0dSUlrich Drepper 3825db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38261da177e4SLinus Torvalds { 3827a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38281da177e4SLinus Torvalds 38291da177e4SLinus Torvalds if (error) 38301da177e4SLinus Torvalds return error; 38311da177e4SLinus Torvalds 3832acfa4380SAl Viro if (!dir->i_op->symlink) 38331da177e4SLinus Torvalds return -EPERM; 38341da177e4SLinus Torvalds 38351da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38361da177e4SLinus Torvalds if (error) 38371da177e4SLinus Torvalds return error; 38381da177e4SLinus Torvalds 38391da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3840a74574aaSStephen Smalley if (!error) 3841f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38421da177e4SLinus Torvalds return error; 38431da177e4SLinus Torvalds } 38444d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38451da177e4SLinus Torvalds 38462e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38472e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38481da177e4SLinus Torvalds { 38492ad94ae6SAl Viro int error; 385091a27b2aSJeff Layton struct filename *from; 38516902d925SDave Hansen struct dentry *dentry; 3852dae6ad8fSAl Viro struct path path; 3853f46d3567SJeff Layton unsigned int lookup_flags = 0; 38541da177e4SLinus Torvalds 38551da177e4SLinus Torvalds from = getname(oldname); 38561da177e4SLinus Torvalds if (IS_ERR(from)) 38571da177e4SLinus Torvalds return PTR_ERR(from); 3858f46d3567SJeff Layton retry: 3859f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 38601da177e4SLinus Torvalds error = PTR_ERR(dentry); 38616902d925SDave Hansen if (IS_ERR(dentry)) 3862dae6ad8fSAl Viro goto out_putname; 38636902d925SDave Hansen 386491a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3865a8104a9fSAl Viro if (!error) 386691a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3867921a1650SAl Viro done_path_create(&path, dentry); 3868f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3869f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3870f46d3567SJeff Layton goto retry; 3871f46d3567SJeff Layton } 38726902d925SDave Hansen out_putname: 38731da177e4SLinus Torvalds putname(from); 38741da177e4SLinus Torvalds return error; 38751da177e4SLinus Torvalds } 38761da177e4SLinus Torvalds 38773480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 38785590ff0dSUlrich Drepper { 38795590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 38805590ff0dSUlrich Drepper } 38815590ff0dSUlrich Drepper 3882146a8595SJ. Bruce Fields /** 3883146a8595SJ. Bruce Fields * vfs_link - create a new link 3884146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3885146a8595SJ. Bruce Fields * @dir: new parent 3886146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3887146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3888146a8595SJ. Bruce Fields * 3889146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3890146a8595SJ. Bruce Fields * 3891146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3892146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3893146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3894146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3895146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3896146a8595SJ. Bruce Fields * 3897146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3898146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3899146a8595SJ. Bruce Fields * to be NFS exported. 3900146a8595SJ. Bruce Fields */ 3901146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39021da177e4SLinus Torvalds { 39031da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39048de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39051da177e4SLinus Torvalds int error; 39061da177e4SLinus Torvalds 39071da177e4SLinus Torvalds if (!inode) 39081da177e4SLinus Torvalds return -ENOENT; 39091da177e4SLinus Torvalds 3910a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39111da177e4SLinus Torvalds if (error) 39121da177e4SLinus Torvalds return error; 39131da177e4SLinus Torvalds 39141da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39151da177e4SLinus Torvalds return -EXDEV; 39161da177e4SLinus Torvalds 39171da177e4SLinus Torvalds /* 39181da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39191da177e4SLinus Torvalds */ 39201da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39211da177e4SLinus Torvalds return -EPERM; 3922acfa4380SAl Viro if (!dir->i_op->link) 39231da177e4SLinus Torvalds return -EPERM; 39247e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39251da177e4SLinus Torvalds return -EPERM; 39261da177e4SLinus Torvalds 39271da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39281da177e4SLinus Torvalds if (error) 39291da177e4SLinus Torvalds return error; 39301da177e4SLinus Torvalds 39317e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3932aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3933f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3934aae8a97dSAneesh Kumar K.V error = -ENOENT; 39358de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39368de52778SAl Viro error = -EMLINK; 3937146a8595SJ. Bruce Fields else { 3938146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3939146a8595SJ. Bruce Fields if (!error) 39401da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3941146a8595SJ. Bruce Fields } 3942f4e0c30cSAl Viro 3943f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3944f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3945f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3946f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3947f4e0c30cSAl Viro } 39487e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3949e31e14ecSStephen Smalley if (!error) 39507e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39511da177e4SLinus Torvalds return error; 39521da177e4SLinus Torvalds } 39534d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39541da177e4SLinus Torvalds 39551da177e4SLinus Torvalds /* 39561da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39571da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 39581da177e4SLinus Torvalds * newname. --KAB 39591da177e4SLinus Torvalds * 39601da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 39611da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 39621da177e4SLinus Torvalds * and other special files. --ADM 39631da177e4SLinus Torvalds */ 39642e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 39652e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 39661da177e4SLinus Torvalds { 39671da177e4SLinus Torvalds struct dentry *new_dentry; 3968dae6ad8fSAl Viro struct path old_path, new_path; 3969146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 397011a7b371SAneesh Kumar K.V int how = 0; 39711da177e4SLinus Torvalds int error; 39721da177e4SLinus Torvalds 397311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3974c04030e1SUlrich Drepper return -EINVAL; 397511a7b371SAneesh Kumar K.V /* 3976f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 3977f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 3978f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 397911a7b371SAneesh Kumar K.V */ 3980f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 3981f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 3982f0cc6ffbSLinus Torvalds return -ENOENT; 398311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 3984f0cc6ffbSLinus Torvalds } 3985c04030e1SUlrich Drepper 398611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 398711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 3988442e31caSJeff Layton retry: 398911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 39901da177e4SLinus Torvalds if (error) 39912ad94ae6SAl Viro return error; 39922ad94ae6SAl Viro 3993442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 3994442e31caSJeff Layton (how & LOOKUP_REVAL)); 39951da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 39966902d925SDave Hansen if (IS_ERR(new_dentry)) 3997dae6ad8fSAl Viro goto out; 3998dae6ad8fSAl Viro 3999dae6ad8fSAl Viro error = -EXDEV; 4000dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4001dae6ad8fSAl Viro goto out_dput; 4002800179c9SKees Cook error = may_linkat(&old_path); 4003800179c9SKees Cook if (unlikely(error)) 4004800179c9SKees Cook goto out_dput; 4005dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4006be6d3e56SKentaro Takeda if (error) 4007a8104a9fSAl Viro goto out_dput; 4008146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 400975c3f29dSDave Hansen out_dput: 4010921a1650SAl Viro done_path_create(&new_path, new_dentry); 4011146a8595SJ. Bruce Fields if (delegated_inode) { 4012146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4013d22e6338SOleg Drokin if (!error) { 4014d22e6338SOleg Drokin path_put(&old_path); 4015146a8595SJ. Bruce Fields goto retry; 4016146a8595SJ. Bruce Fields } 4017d22e6338SOleg Drokin } 4018442e31caSJeff Layton if (retry_estale(error, how)) { 4019d22e6338SOleg Drokin path_put(&old_path); 4020442e31caSJeff Layton how |= LOOKUP_REVAL; 4021442e31caSJeff Layton goto retry; 4022442e31caSJeff Layton } 40231da177e4SLinus Torvalds out: 40242d8f3038SAl Viro path_put(&old_path); 40251da177e4SLinus Torvalds 40261da177e4SLinus Torvalds return error; 40271da177e4SLinus Torvalds } 40281da177e4SLinus Torvalds 40293480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40305590ff0dSUlrich Drepper { 4031c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40325590ff0dSUlrich Drepper } 40335590ff0dSUlrich Drepper 4034bc27027aSMiklos Szeredi /** 4035bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4036bc27027aSMiklos Szeredi * @old_dir: parent of source 4037bc27027aSMiklos Szeredi * @old_dentry: source 4038bc27027aSMiklos Szeredi * @new_dir: parent of destination 4039bc27027aSMiklos Szeredi * @new_dentry: destination 4040bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4041520c8b16SMiklos Szeredi * @flags: rename flags 4042bc27027aSMiklos Szeredi * 4043bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4044bc27027aSMiklos Szeredi * 4045bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4046bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4047bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4048bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4049bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4050bc27027aSMiklos Szeredi * so. 4051bc27027aSMiklos Szeredi * 4052bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4053bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4054bc27027aSMiklos Szeredi * to be NFS exported. 4055bc27027aSMiklos Szeredi * 40561da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40571da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 40581da177e4SLinus Torvalds * Problems: 4059d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 40601da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 40611da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4062a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 40631da177e4SLinus Torvalds * story. 40646cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 40656cedba89SJ. Bruce Fields * and source (if it is not a directory). 40661b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 40671da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 40681da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4069a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 40701da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 40711da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 40721da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4073a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 40741da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 40751da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 40761da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4077e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 40781b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 40791da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4080c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 40811da177e4SLinus Torvalds * locking]. 40821da177e4SLinus Torvalds */ 40831da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 40848e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4085520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 40861da177e4SLinus Torvalds { 40871da177e4SLinus Torvalds int error; 4088bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 408959b0df21SEric Paris const unsigned char *old_name; 4090bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4091bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4092da1ce067SMiklos Szeredi bool new_is_dir = false; 4093da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 40941da177e4SLinus Torvalds 4095bc27027aSMiklos Szeredi if (source == target) 40961da177e4SLinus Torvalds return 0; 40971da177e4SLinus Torvalds 40981da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 40991da177e4SLinus Torvalds if (error) 41001da177e4SLinus Torvalds return error; 41011da177e4SLinus Torvalds 4102da1ce067SMiklos Szeredi if (!target) { 4103a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4104da1ce067SMiklos Szeredi } else { 4105da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4106da1ce067SMiklos Szeredi 4107da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41081da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4109da1ce067SMiklos Szeredi else 4110da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4111da1ce067SMiklos Szeredi } 41121da177e4SLinus Torvalds if (error) 41131da177e4SLinus Torvalds return error; 41141da177e4SLinus Torvalds 41157177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41161da177e4SLinus Torvalds return -EPERM; 41171da177e4SLinus Torvalds 4118520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4119520c8b16SMiklos Szeredi return -EINVAL; 4120520c8b16SMiklos Szeredi 4121bc27027aSMiklos Szeredi /* 4122bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4123bc27027aSMiklos Szeredi * we'll need to flip '..'. 4124bc27027aSMiklos Szeredi */ 4125da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4126da1ce067SMiklos Szeredi if (is_dir) { 4127bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4128bc27027aSMiklos Szeredi if (error) 4129bc27027aSMiklos Szeredi return error; 4130bc27027aSMiklos Szeredi } 4131da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4132da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4133da1ce067SMiklos Szeredi if (error) 4134da1ce067SMiklos Szeredi return error; 4135da1ce067SMiklos Szeredi } 4136da1ce067SMiklos Szeredi } 41370eeca283SRobert Love 41380b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41390b3974ebSMiklos Szeredi flags); 4140bc27027aSMiklos Szeredi if (error) 4141bc27027aSMiklos Szeredi return error; 4142bc27027aSMiklos Szeredi 4143bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4144bc27027aSMiklos Szeredi dget(new_dentry); 4145da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4146bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4147bc27027aSMiklos Szeredi else if (target) 4148bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4149bc27027aSMiklos Szeredi 4150bc27027aSMiklos Szeredi error = -EBUSY; 41517af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4152bc27027aSMiklos Szeredi goto out; 4153bc27027aSMiklos Szeredi 4154da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4155bc27027aSMiklos Szeredi error = -EMLINK; 4156da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4157bc27027aSMiklos Szeredi goto out; 4158da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4159da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4160da1ce067SMiklos Szeredi goto out; 4161da1ce067SMiklos Szeredi } 4162da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4163bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4164da1ce067SMiklos Szeredi if (!is_dir) { 4165bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4166bc27027aSMiklos Szeredi if (error) 4167bc27027aSMiklos Szeredi goto out; 4168da1ce067SMiklos Szeredi } 4169da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4170bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4171bc27027aSMiklos Szeredi if (error) 4172bc27027aSMiklos Szeredi goto out; 4173bc27027aSMiklos Szeredi } 41747177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4175520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4176520c8b16SMiklos Szeredi new_dir, new_dentry); 4177520c8b16SMiklos Szeredi } else { 41787177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4179520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4180520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4181520c8b16SMiklos Szeredi } 4182bc27027aSMiklos Szeredi if (error) 4183bc27027aSMiklos Szeredi goto out; 4184bc27027aSMiklos Szeredi 4185da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 41861da177e4SLinus Torvalds if (is_dir) 4187bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4188bc27027aSMiklos Szeredi dont_mount(new_dentry); 41898ed936b5SEric W. Biederman detach_mounts(new_dentry); 4190bc27027aSMiklos Szeredi } 4191da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4192da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4193bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4194da1ce067SMiklos Szeredi else 4195da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4196da1ce067SMiklos Szeredi } 4197bc27027aSMiklos Szeredi out: 4198da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4199bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4200bc27027aSMiklos Szeredi else if (target) 4201bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4202bc27027aSMiklos Szeredi dput(new_dentry); 4203da1ce067SMiklos Szeredi if (!error) { 4204123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4205da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4206da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4207da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4208da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4209da1ce067SMiklos Szeredi } 4210da1ce067SMiklos Szeredi } 42110eeca283SRobert Love fsnotify_oldname_free(old_name); 42120eeca283SRobert Love 42131da177e4SLinus Torvalds return error; 42141da177e4SLinus Torvalds } 42154d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42161da177e4SLinus Torvalds 4217520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4218520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42191da177e4SLinus Torvalds { 42201da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 42211da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42221da177e4SLinus Torvalds struct dentry *trap; 42231da177e4SLinus Torvalds struct nameidata oldnd, newnd; 42248e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 422591a27b2aSJeff Layton struct filename *from; 422691a27b2aSJeff Layton struct filename *to; 4227c6a94284SJeff Layton unsigned int lookup_flags = 0; 4228c6a94284SJeff Layton bool should_retry = false; 42292ad94ae6SAl Viro int error; 4230520c8b16SMiklos Szeredi 42310d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4232da1ce067SMiklos Szeredi return -EINVAL; 4233da1ce067SMiklos Szeredi 42340d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42350d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4236520c8b16SMiklos Szeredi return -EINVAL; 4237520c8b16SMiklos Szeredi 42380d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42390d7a8555SMiklos Szeredi return -EPERM; 42400d7a8555SMiklos Szeredi 4241c6a94284SJeff Layton retry: 4242c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 424391a27b2aSJeff Layton if (IS_ERR(from)) { 424491a27b2aSJeff Layton error = PTR_ERR(from); 42451da177e4SLinus Torvalds goto exit; 424691a27b2aSJeff Layton } 42471da177e4SLinus Torvalds 4248c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 424991a27b2aSJeff Layton if (IS_ERR(to)) { 425091a27b2aSJeff Layton error = PTR_ERR(to); 42511da177e4SLinus Torvalds goto exit1; 425291a27b2aSJeff Layton } 42531da177e4SLinus Torvalds 42541da177e4SLinus Torvalds error = -EXDEV; 42554ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 42561da177e4SLinus Torvalds goto exit2; 42571da177e4SLinus Torvalds 42584ac91378SJan Blunck old_dir = oldnd.path.dentry; 42591da177e4SLinus Torvalds error = -EBUSY; 42601da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 42611da177e4SLinus Torvalds goto exit2; 42621da177e4SLinus Torvalds 42634ac91378SJan Blunck new_dir = newnd.path.dentry; 42640a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 42650a7c3937SMiklos Szeredi error = -EEXIST; 42661da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 42671da177e4SLinus Torvalds goto exit2; 42681da177e4SLinus Torvalds 4269c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4270c30dabfeSJan Kara if (error) 4271c30dabfeSJan Kara goto exit2; 4272c30dabfeSJan Kara 42730612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 42740612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 4275da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42764e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 42770612d9fbSOGAWA Hirofumi 42788e6d782cSJ. Bruce Fields retry_deleg: 42791da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 42801da177e4SLinus Torvalds 428149705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 42821da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 42831da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 42841da177e4SLinus Torvalds goto exit3; 42851da177e4SLinus Torvalds /* source must exist */ 42861da177e4SLinus Torvalds error = -ENOENT; 4287b18825a7SDavid Howells if (d_is_negative(old_dentry)) 42881da177e4SLinus Torvalds goto exit4; 428949705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 42901da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42911da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 42921da177e4SLinus Torvalds goto exit4; 42930a7c3937SMiklos Szeredi error = -EEXIST; 42940a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 42950a7c3937SMiklos Szeredi goto exit5; 4296da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4297da1ce067SMiklos Szeredi error = -ENOENT; 4298da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4299da1ce067SMiklos Szeredi goto exit5; 4300da1ce067SMiklos Szeredi 4301da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4302da1ce067SMiklos Szeredi error = -ENOTDIR; 4303da1ce067SMiklos Szeredi if (newnd.last.name[newnd.last.len]) 4304da1ce067SMiklos Szeredi goto exit5; 4305da1ce067SMiklos Szeredi } 4306da1ce067SMiklos Szeredi } 43070a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43080a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43090a7c3937SMiklos Szeredi error = -ENOTDIR; 43100a7c3937SMiklos Szeredi if (oldnd.last.name[oldnd.last.len]) 43110a7c3937SMiklos Szeredi goto exit5; 4312da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) 43130a7c3937SMiklos Szeredi goto exit5; 43140a7c3937SMiklos Szeredi } 43150a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43160a7c3937SMiklos Szeredi error = -EINVAL; 43170a7c3937SMiklos Szeredi if (old_dentry == trap) 43180a7c3937SMiklos Szeredi goto exit5; 43191da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4320da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43211da177e4SLinus Torvalds error = -ENOTEMPTY; 43221da177e4SLinus Torvalds if (new_dentry == trap) 43231da177e4SLinus Torvalds goto exit5; 43241da177e4SLinus Torvalds 4325be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 43260b3974ebSMiklos Szeredi &newnd.path, new_dentry, flags); 4327be6d3e56SKentaro Takeda if (error) 4328c30dabfeSJan Kara goto exit5; 43291da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 43308e6d782cSJ. Bruce Fields new_dir->d_inode, new_dentry, 4331520c8b16SMiklos Szeredi &delegated_inode, flags); 43321da177e4SLinus Torvalds exit5: 43331da177e4SLinus Torvalds dput(new_dentry); 43341da177e4SLinus Torvalds exit4: 43351da177e4SLinus Torvalds dput(old_dentry); 43361da177e4SLinus Torvalds exit3: 43371da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 43388e6d782cSJ. Bruce Fields if (delegated_inode) { 43398e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43408e6d782cSJ. Bruce Fields if (!error) 43418e6d782cSJ. Bruce Fields goto retry_deleg; 43428e6d782cSJ. Bruce Fields } 4343c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 43441da177e4SLinus Torvalds exit2: 4345c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4346c6a94284SJeff Layton should_retry = true; 43471d957f9bSJan Blunck path_put(&newnd.path); 43482ad94ae6SAl Viro putname(to); 43491da177e4SLinus Torvalds exit1: 43501d957f9bSJan Blunck path_put(&oldnd.path); 43511da177e4SLinus Torvalds putname(from); 4352c6a94284SJeff Layton if (should_retry) { 4353c6a94284SJeff Layton should_retry = false; 4354c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4355c6a94284SJeff Layton goto retry; 4356c6a94284SJeff Layton } 43572ad94ae6SAl Viro exit: 43581da177e4SLinus Torvalds return error; 43591da177e4SLinus Torvalds } 43601da177e4SLinus Torvalds 4361520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4362520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4363520c8b16SMiklos Szeredi { 4364520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4365520c8b16SMiklos Szeredi } 4366520c8b16SMiklos Szeredi 4367a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 43685590ff0dSUlrich Drepper { 4369520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43705590ff0dSUlrich Drepper } 43715590ff0dSUlrich Drepper 4372787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4373787fb6bcSMiklos Szeredi { 4374787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4375787fb6bcSMiklos Szeredi if (error) 4376787fb6bcSMiklos Szeredi return error; 4377787fb6bcSMiklos Szeredi 4378787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4379787fb6bcSMiklos Szeredi return -EPERM; 4380787fb6bcSMiklos Szeredi 4381787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4382787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4383787fb6bcSMiklos Szeredi } 4384787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4385787fb6bcSMiklos Szeredi 43865d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 43871da177e4SLinus Torvalds { 43885d826c84SAl Viro int len = PTR_ERR(link); 43891da177e4SLinus Torvalds if (IS_ERR(link)) 43901da177e4SLinus Torvalds goto out; 43911da177e4SLinus Torvalds 43921da177e4SLinus Torvalds len = strlen(link); 43931da177e4SLinus Torvalds if (len > (unsigned) buflen) 43941da177e4SLinus Torvalds len = buflen; 43951da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 43961da177e4SLinus Torvalds len = -EFAULT; 43971da177e4SLinus Torvalds out: 43981da177e4SLinus Torvalds return len; 43991da177e4SLinus Torvalds } 44005d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44011da177e4SLinus Torvalds 44021da177e4SLinus Torvalds /* 44031da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44041da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44051da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44061da177e4SLinus Torvalds */ 44071da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44081da177e4SLinus Torvalds { 44091da177e4SLinus Torvalds struct nameidata nd; 4410cc314eefSLinus Torvalds void *cookie; 4411694a1764SMarcin Slusarz int res; 4412cc314eefSLinus Torvalds 44131da177e4SLinus Torvalds nd.depth = 0; 4414cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4415694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4416694a1764SMarcin Slusarz return PTR_ERR(cookie); 4417694a1764SMarcin Slusarz 44185d826c84SAl Viro res = readlink_copy(buffer, buflen, nd_get_link(&nd)); 44191da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4420cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4421694a1764SMarcin Slusarz return res; 44221da177e4SLinus Torvalds } 44234d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44241da177e4SLinus Torvalds 44251da177e4SLinus Torvalds /* get the link contents into pagecache */ 44261da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44271da177e4SLinus Torvalds { 4428ebd09abbSDuane Griffin char *kaddr; 44291da177e4SLinus Torvalds struct page *page; 44301da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4431090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44321da177e4SLinus Torvalds if (IS_ERR(page)) 44336fe6900eSNick Piggin return (char*)page; 44341da177e4SLinus Torvalds *ppage = page; 4435ebd09abbSDuane Griffin kaddr = kmap(page); 4436ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4437ebd09abbSDuane Griffin return kaddr; 44381da177e4SLinus Torvalds } 44391da177e4SLinus Torvalds 44401da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44411da177e4SLinus Torvalds { 44421da177e4SLinus Torvalds struct page *page = NULL; 44435d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44441da177e4SLinus Torvalds if (page) { 44451da177e4SLinus Torvalds kunmap(page); 44461da177e4SLinus Torvalds page_cache_release(page); 44471da177e4SLinus Torvalds } 44481da177e4SLinus Torvalds return res; 44491da177e4SLinus Torvalds } 44504d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44511da177e4SLinus Torvalds 4452cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 44531da177e4SLinus Torvalds { 4454cc314eefSLinus Torvalds struct page *page = NULL; 44551da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4456cc314eefSLinus Torvalds return page; 44571da177e4SLinus Torvalds } 44584d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 44591da177e4SLinus Torvalds 4460cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 44611da177e4SLinus Torvalds { 4462cc314eefSLinus Torvalds struct page *page = cookie; 4463cc314eefSLinus Torvalds 4464cc314eefSLinus Torvalds if (page) { 44651da177e4SLinus Torvalds kunmap(page); 44661da177e4SLinus Torvalds page_cache_release(page); 44671da177e4SLinus Torvalds } 44681da177e4SLinus Torvalds } 44694d359507SAl Viro EXPORT_SYMBOL(page_put_link); 44701da177e4SLinus Torvalds 447154566b2cSNick Piggin /* 447254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 447354566b2cSNick Piggin */ 447454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 44751da177e4SLinus Torvalds { 44761da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 44770adb25d2SKirill Korotaev struct page *page; 4478afddba49SNick Piggin void *fsdata; 4479beb497abSDmitriy Monakhov int err; 44801da177e4SLinus Torvalds char *kaddr; 448154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 448254566b2cSNick Piggin if (nofs) 448354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 44841da177e4SLinus Torvalds 44857e53cac4SNeilBrown retry: 4486afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 448754566b2cSNick Piggin flags, &page, &fsdata); 44881da177e4SLinus Torvalds if (err) 4489afddba49SNick Piggin goto fail; 4490afddba49SNick Piggin 4491e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 44921da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4493e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4494afddba49SNick Piggin 4495afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4496afddba49SNick Piggin page, fsdata); 44971da177e4SLinus Torvalds if (err < 0) 44981da177e4SLinus Torvalds goto fail; 4499afddba49SNick Piggin if (err < len-1) 4500afddba49SNick Piggin goto retry; 4501afddba49SNick Piggin 45021da177e4SLinus Torvalds mark_inode_dirty(inode); 45031da177e4SLinus Torvalds return 0; 45041da177e4SLinus Torvalds fail: 45051da177e4SLinus Torvalds return err; 45061da177e4SLinus Torvalds } 45074d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45081da177e4SLinus Torvalds 45090adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45100adb25d2SKirill Korotaev { 45110adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 451254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45130adb25d2SKirill Korotaev } 45144d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45150adb25d2SKirill Korotaev 451692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45171da177e4SLinus Torvalds .readlink = generic_readlink, 45181da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45191da177e4SLinus Torvalds .put_link = page_put_link, 45201da177e4SLinus Torvalds }; 45211da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4522