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; 246fd3522fdSPaul Moore audit_getname(result); 247c4ad8f98SLinus Torvalds 248c4ad8f98SLinus Torvalds return result; 249c4ad8f98SLinus Torvalds } 250c4ad8f98SLinus Torvalds 2511da177e4SLinus Torvalds #ifdef CONFIG_AUDITSYSCALL 25291a27b2aSJeff Layton void putname(struct filename *name) 2531da177e4SLinus Torvalds { 2545ac3a9c2SAl Viro if (unlikely(!audit_dummy_context())) 25591a27b2aSJeff Layton return audit_putname(name); 25691a27b2aSJeff Layton final_putname(name); 2571da177e4SLinus Torvalds } 2581da177e4SLinus Torvalds #endif 2591da177e4SLinus Torvalds 260e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 261e77819e5SLinus Torvalds { 26284635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 263e77819e5SLinus Torvalds struct posix_acl *acl; 264e77819e5SLinus Torvalds 265e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2663567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2673567866bSAl Viro if (!acl) 268e77819e5SLinus Torvalds return -EAGAIN; 2693567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2703567866bSAl Viro if (acl == ACL_NOT_CACHED) 271e77819e5SLinus Torvalds return -ECHILD; 272206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 273e77819e5SLinus Torvalds } 274e77819e5SLinus Torvalds 2752982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2764e34e719SChristoph Hellwig if (IS_ERR(acl)) 2774e34e719SChristoph Hellwig return PTR_ERR(acl); 278e77819e5SLinus Torvalds if (acl) { 279e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 280e77819e5SLinus Torvalds posix_acl_release(acl); 281e77819e5SLinus Torvalds return error; 282e77819e5SLinus Torvalds } 28384635d68SLinus Torvalds #endif 284e77819e5SLinus Torvalds 285e77819e5SLinus Torvalds return -EAGAIN; 286e77819e5SLinus Torvalds } 287e77819e5SLinus Torvalds 2885909ccaaSLinus Torvalds /* 289948409c7SAndreas Gruenbacher * This does the basic permission checking 2905909ccaaSLinus Torvalds */ 2917e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2925909ccaaSLinus Torvalds { 29326cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2945909ccaaSLinus Torvalds 2958e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2965909ccaaSLinus Torvalds mode >>= 6; 2975909ccaaSLinus Torvalds else { 298e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2997e40145eSAl Viro int error = check_acl(inode, mask); 3005909ccaaSLinus Torvalds if (error != -EAGAIN) 3015909ccaaSLinus Torvalds return error; 3025909ccaaSLinus Torvalds } 3035909ccaaSLinus Torvalds 3045909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3055909ccaaSLinus Torvalds mode >>= 3; 3065909ccaaSLinus Torvalds } 3075909ccaaSLinus Torvalds 3085909ccaaSLinus Torvalds /* 3095909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3105909ccaaSLinus Torvalds */ 3119c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3125909ccaaSLinus Torvalds return 0; 3135909ccaaSLinus Torvalds return -EACCES; 3145909ccaaSLinus Torvalds } 3151da177e4SLinus Torvalds 3161da177e4SLinus Torvalds /** 3171da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3181da177e4SLinus Torvalds * @inode: inode to check access rights for 3198fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3201da177e4SLinus Torvalds * 3211da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3221da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3231da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 324b74c79e9SNick Piggin * are used for other things. 325b74c79e9SNick Piggin * 326b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 327b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 328b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3291da177e4SLinus Torvalds */ 3302830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3311da177e4SLinus Torvalds { 3325909ccaaSLinus Torvalds int ret; 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds /* 335948409c7SAndreas Gruenbacher * Do the basic permission checks. 3361da177e4SLinus Torvalds */ 3377e40145eSAl Viro ret = acl_permission_check(inode, mask); 3385909ccaaSLinus Torvalds if (ret != -EACCES) 3395909ccaaSLinus Torvalds return ret; 3401da177e4SLinus Torvalds 341d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 342d594e7ecSAl Viro /* DACs are overridable for directories */ 34323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 344d594e7ecSAl Viro return 0; 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 349d594e7ecSAl Viro return -EACCES; 350d594e7ecSAl Viro } 3511da177e4SLinus Torvalds /* 3521da177e4SLinus Torvalds * Read/write DACs are always overridable. 353d594e7ecSAl Viro * Executable DACs are overridable when there is 354d594e7ecSAl Viro * at least one exec bit set. 3551da177e4SLinus Torvalds */ 356d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35723adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3581da177e4SLinus Torvalds return 0; 3591da177e4SLinus Torvalds 3601da177e4SLinus Torvalds /* 3611da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3621da177e4SLinus Torvalds */ 3637ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 364d594e7ecSAl Viro if (mask == MAY_READ) 36523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3661da177e4SLinus Torvalds return 0; 3671da177e4SLinus Torvalds 3681da177e4SLinus Torvalds return -EACCES; 3691da177e4SLinus Torvalds } 3704d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3711da177e4SLinus Torvalds 3723ddcd056SLinus Torvalds /* 3733ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3743ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3753ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3763ddcd056SLinus Torvalds * permission function, use the fast case". 3773ddcd056SLinus Torvalds */ 3783ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3793ddcd056SLinus Torvalds { 3803ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3813ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3823ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3833ddcd056SLinus Torvalds 3843ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3853ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3863ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3873ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds return generic_permission(inode, mask); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds 392cb23beb5SChristoph Hellwig /** 3930bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3940bdaea90SDavid Howells * @inode: Inode to check permission on 3950bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 396cb23beb5SChristoph Hellwig * 3970bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 398948409c7SAndreas Gruenbacher * 399948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4000bdaea90SDavid Howells * 4010bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4020bdaea90SDavid Howells * inode_permission(). 403cb23beb5SChristoph Hellwig */ 4040bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4051da177e4SLinus Torvalds { 406e6305c43SAl Viro int retval; 4071da177e4SLinus Torvalds 4083ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4091da177e4SLinus Torvalds /* 4101da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4131da177e4SLinus Torvalds return -EACCES; 4141da177e4SLinus Torvalds } 4151da177e4SLinus Torvalds 4163ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4171da177e4SLinus Torvalds if (retval) 4181da177e4SLinus Torvalds return retval; 4191da177e4SLinus Torvalds 42008ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 42108ce5f16SSerge E. Hallyn if (retval) 42208ce5f16SSerge E. Hallyn return retval; 42308ce5f16SSerge E. Hallyn 424d09ca739SEric Paris return security_inode_permission(inode, mask); 4251da177e4SLinus Torvalds } 426bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4271da177e4SLinus Torvalds 428f4d6ff89SAl Viro /** 4290bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4300bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 43155852635SRandy Dunlap * @inode: Inode to check permission on 4320bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4330bdaea90SDavid Howells * 4340bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4350bdaea90SDavid Howells */ 4360bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4370bdaea90SDavid Howells { 4380bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4390bdaea90SDavid Howells umode_t mode = inode->i_mode; 4400bdaea90SDavid Howells 4410bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4420bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4430bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4440bdaea90SDavid Howells return -EROFS; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells return 0; 4470bdaea90SDavid Howells } 4480bdaea90SDavid Howells 4490bdaea90SDavid Howells /** 4500bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4510bdaea90SDavid Howells * @inode: Inode to check permission on 4520bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4530bdaea90SDavid Howells * 4540bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4550bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4560bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4570bdaea90SDavid Howells * 4580bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4590bdaea90SDavid Howells */ 4600bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4610bdaea90SDavid Howells { 4620bdaea90SDavid Howells int retval; 4630bdaea90SDavid Howells 4640bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4650bdaea90SDavid Howells if (retval) 4660bdaea90SDavid Howells return retval; 4670bdaea90SDavid Howells return __inode_permission(inode, mask); 4680bdaea90SDavid Howells } 4694d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4700bdaea90SDavid Howells 4710bdaea90SDavid Howells /** 4725dd784d0SJan Blunck * path_get - get a reference to a path 4735dd784d0SJan Blunck * @path: path to get the reference to 4745dd784d0SJan Blunck * 4755dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4765dd784d0SJan Blunck */ 477dcf787f3SAl Viro void path_get(const struct path *path) 4785dd784d0SJan Blunck { 4795dd784d0SJan Blunck mntget(path->mnt); 4805dd784d0SJan Blunck dget(path->dentry); 4815dd784d0SJan Blunck } 4825dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4835dd784d0SJan Blunck 4845dd784d0SJan Blunck /** 4851d957f9bSJan Blunck * path_put - put a reference to a path 4861d957f9bSJan Blunck * @path: path to put the reference to 4871d957f9bSJan Blunck * 4881d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4891d957f9bSJan Blunck */ 490dcf787f3SAl Viro void path_put(const struct path *path) 4911da177e4SLinus Torvalds { 4921d957f9bSJan Blunck dput(path->dentry); 4931d957f9bSJan Blunck mntput(path->mnt); 4941da177e4SLinus Torvalds } 4951d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4961da177e4SLinus Torvalds 4971f55a6ecSAl Viro struct nameidata { 4981f55a6ecSAl Viro struct path path; 4991f55a6ecSAl Viro struct qstr last; 5001f55a6ecSAl Viro struct path root; 5011f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5021f55a6ecSAl Viro unsigned int flags; 5031f55a6ecSAl Viro unsigned seq, m_seq; 5041f55a6ecSAl Viro int last_type; 5051f55a6ecSAl Viro unsigned depth; 5065e53084dSAl Viro struct file *base; 5071f55a6ecSAl Viro char *saved_names[MAX_NESTED_LINKS + 1]; 5081f55a6ecSAl Viro }; 5091f55a6ecSAl Viro 51019660af7SAl Viro /* 51131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 51219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 51319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 51419660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 51519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 51619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 51719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 51819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 51931e6b01fSNick Piggin */ 52031e6b01fSNick Piggin 52131e6b01fSNick Piggin /** 52219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 52319660af7SAl Viro * @nd: nameidata pathwalk data 52419660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 52539191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 52631e6b01fSNick Piggin * 52719660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 52819660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 52919660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 53031e6b01fSNick Piggin */ 53119660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 53231e6b01fSNick Piggin { 53331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 53431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 53531e6b01fSNick Piggin 53631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 537e5c832d5SLinus Torvalds 538e5c832d5SLinus Torvalds /* 53948a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 54048a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 54148a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 54248a066e7SAl Viro * before returning. Do vfsmount first; if dentry 54348a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 54448a066e7SAl Viro * and rely on dput(NULL) being a no-op. 545e5c832d5SLinus Torvalds */ 54648a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 547e5c832d5SLinus Torvalds return -ECHILD; 548e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 54915570086SLinus Torvalds 55048a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 55148a066e7SAl Viro nd->path.dentry = NULL; 552d870b4a1SAl Viro goto out; 55348a066e7SAl Viro } 55448a066e7SAl Viro 55515570086SLinus Torvalds /* 55615570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 55715570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 55815570086SLinus Torvalds * 55915570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 56015570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 56115570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 56215570086SLinus Torvalds * since we checked the sequence number of the parent after we got 56315570086SLinus Torvalds * the child sequence number. So we know the parent must still 56415570086SLinus Torvalds * be valid if the child sequence number is still valid. 56515570086SLinus Torvalds */ 56619660af7SAl Viro if (!dentry) { 567e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 568e5c832d5SLinus Torvalds goto out; 56919660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 57019660af7SAl Viro } else { 571e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 572e5c832d5SLinus Torvalds goto out; 573e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 574e5c832d5SLinus Torvalds goto drop_dentry; 57519660af7SAl Viro } 576e5c832d5SLinus Torvalds 577e5c832d5SLinus Torvalds /* 578e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 579e5c832d5SLinus Torvalds * still valid and get it if required. 580e5c832d5SLinus Torvalds */ 581e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 582e5c832d5SLinus Torvalds spin_lock(&fs->lock); 583e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 584e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 58531e6b01fSNick Piggin path_get(&nd->root); 58631e6b01fSNick Piggin spin_unlock(&fs->lock); 58731e6b01fSNick Piggin } 58831e6b01fSNick Piggin 5898b61e74fSAl Viro rcu_read_unlock(); 59031e6b01fSNick Piggin return 0; 59119660af7SAl Viro 592e5c832d5SLinus Torvalds unlock_and_drop_dentry: 59331e6b01fSNick Piggin spin_unlock(&fs->lock); 594e5c832d5SLinus Torvalds drop_dentry: 5958b61e74fSAl Viro rcu_read_unlock(); 596e5c832d5SLinus Torvalds dput(dentry); 597d0d27277SLinus Torvalds goto drop_root_mnt; 598e5c832d5SLinus Torvalds out: 5998b61e74fSAl Viro rcu_read_unlock(); 600d0d27277SLinus Torvalds drop_root_mnt: 601d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 602d0d27277SLinus Torvalds nd->root.mnt = NULL; 60331e6b01fSNick Piggin return -ECHILD; 60431e6b01fSNick Piggin } 60531e6b01fSNick Piggin 6064ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 60734286d66SNick Piggin { 6084ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 60934286d66SNick Piggin } 61034286d66SNick Piggin 6119f1fafeeSAl Viro /** 6129f1fafeeSAl Viro * complete_walk - successful completion of path walk 6139f1fafeeSAl Viro * @nd: pointer nameidata 61439159de2SJeff Layton * 6159f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6169f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6179f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6189f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6199f1fafeeSAl Viro * need to drop nd->path. 62039159de2SJeff Layton */ 6219f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 62239159de2SJeff Layton { 62316c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 62439159de2SJeff Layton int status; 62539159de2SJeff Layton 6269f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6279f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6289f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6299f1fafeeSAl Viro nd->root.mnt = NULL; 63015570086SLinus Torvalds 63148a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6328b61e74fSAl Viro rcu_read_unlock(); 63348a066e7SAl Viro return -ECHILD; 63448a066e7SAl Viro } 635e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6368b61e74fSAl Viro rcu_read_unlock(); 63748a066e7SAl Viro mntput(nd->path.mnt); 6389f1fafeeSAl Viro return -ECHILD; 6399f1fafeeSAl Viro } 640e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6418b61e74fSAl Viro rcu_read_unlock(); 642e5c832d5SLinus Torvalds dput(dentry); 64348a066e7SAl Viro mntput(nd->path.mnt); 644e5c832d5SLinus Torvalds return -ECHILD; 645e5c832d5SLinus Torvalds } 6468b61e74fSAl Viro rcu_read_unlock(); 6479f1fafeeSAl Viro } 6489f1fafeeSAl Viro 64916c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 65039159de2SJeff Layton return 0; 65139159de2SJeff Layton 652ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 65316c2cd71SAl Viro return 0; 65416c2cd71SAl Viro 655ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 65639159de2SJeff Layton if (status > 0) 65739159de2SJeff Layton return 0; 65839159de2SJeff Layton 65916c2cd71SAl Viro if (!status) 66039159de2SJeff Layton status = -ESTALE; 66116c2cd71SAl Viro 6629f1fafeeSAl Viro path_put(&nd->path); 66339159de2SJeff Layton return status; 66439159de2SJeff Layton } 66539159de2SJeff Layton 6662a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6672a737871SAl Viro { 668f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6692a737871SAl Viro } 6702a737871SAl Viro 6716de88d72SAl Viro static int link_path_walk(const char *, struct nameidata *); 6726de88d72SAl Viro 6737bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 67431e6b01fSNick Piggin { 67531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6767bd88377SAl Viro unsigned seq, res; 677c28cc364SNick Piggin 678c28cc364SNick Piggin do { 679c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 68031e6b01fSNick Piggin nd->root = fs->root; 6817bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 682c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6837bd88377SAl Viro return res; 68431e6b01fSNick Piggin } 68531e6b01fSNick Piggin 6861d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 687051d3812SIan Kent { 688051d3812SIan Kent dput(path->dentry); 6894ac91378SJan Blunck if (path->mnt != nd->path.mnt) 690051d3812SIan Kent mntput(path->mnt); 691051d3812SIan Kent } 692051d3812SIan Kent 6937b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6947b9337aaSNick Piggin struct nameidata *nd) 695051d3812SIan Kent { 69631e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6974ac91378SJan Blunck dput(nd->path.dentry); 69831e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6994ac91378SJan Blunck mntput(nd->path.mnt); 7009a229683SHuang Shijie } 70131e6b01fSNick Piggin nd->path.mnt = path->mnt; 7024ac91378SJan Blunck nd->path.dentry = path->dentry; 703051d3812SIan Kent } 704051d3812SIan Kent 705b5fb63c1SChristoph Hellwig /* 706b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 707b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 708b5fb63c1SChristoph Hellwig */ 709b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 710b5fb63c1SChristoph Hellwig { 711b5fb63c1SChristoph Hellwig path_put(&nd->path); 712b5fb63c1SChristoph Hellwig 713b5fb63c1SChristoph Hellwig nd->path = *path; 714b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 715b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 716b5fb63c1SChristoph Hellwig } 717b5fb63c1SChristoph Hellwig 7181f55a6ecSAl Viro void nd_set_link(struct nameidata *nd, char *path) 7191f55a6ecSAl Viro { 7201f55a6ecSAl Viro nd->saved_names[nd->depth] = path; 7211f55a6ecSAl Viro } 7221f55a6ecSAl Viro EXPORT_SYMBOL(nd_set_link); 7231f55a6ecSAl Viro 7241f55a6ecSAl Viro char *nd_get_link(struct nameidata *nd) 7251f55a6ecSAl Viro { 7261f55a6ecSAl Viro return nd->saved_names[nd->depth]; 7271f55a6ecSAl Viro } 7281f55a6ecSAl Viro EXPORT_SYMBOL(nd_get_link); 7291f55a6ecSAl Viro 730574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 731574197e0SAl Viro { 732574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 7336d7b5aaeSAl Viro if (inode->i_op->put_link) 734574197e0SAl Viro inode->i_op->put_link(link->dentry, nd, cookie); 735574197e0SAl Viro path_put(link); 736574197e0SAl Viro } 737574197e0SAl Viro 738561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 739561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 740800179c9SKees Cook 741800179c9SKees Cook /** 742800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 743800179c9SKees Cook * @link: The path of the symlink 74455852635SRandy Dunlap * @nd: nameidata pathwalk data 745800179c9SKees Cook * 746800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 747800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 748800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 749800179c9SKees Cook * processes from failing races against path names that may change out 750800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 751800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 752800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 753800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 754800179c9SKees Cook * 755800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 756800179c9SKees Cook */ 757800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 758800179c9SKees Cook { 759800179c9SKees Cook const struct inode *inode; 760800179c9SKees Cook const struct inode *parent; 761800179c9SKees Cook 762800179c9SKees Cook if (!sysctl_protected_symlinks) 763800179c9SKees Cook return 0; 764800179c9SKees Cook 765800179c9SKees Cook /* Allowed if owner and follower match. */ 766800179c9SKees Cook inode = link->dentry->d_inode; 76781abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 768800179c9SKees Cook return 0; 769800179c9SKees Cook 770800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 771800179c9SKees Cook parent = nd->path.dentry->d_inode; 772800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 773800179c9SKees Cook return 0; 774800179c9SKees Cook 775800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 77681abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 777800179c9SKees Cook return 0; 778800179c9SKees Cook 779ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 780800179c9SKees Cook path_put_conditional(link, nd); 781800179c9SKees Cook path_put(&nd->path); 782800179c9SKees Cook return -EACCES; 783800179c9SKees Cook } 784800179c9SKees Cook 785800179c9SKees Cook /** 786800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 787800179c9SKees Cook * @inode: the source inode to hardlink from 788800179c9SKees Cook * 789800179c9SKees Cook * Return false if at least one of the following conditions: 790800179c9SKees Cook * - inode is not a regular file 791800179c9SKees Cook * - inode is setuid 792800179c9SKees Cook * - inode is setgid and group-exec 793800179c9SKees Cook * - access failure for read and write 794800179c9SKees Cook * 795800179c9SKees Cook * Otherwise returns true. 796800179c9SKees Cook */ 797800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 798800179c9SKees Cook { 799800179c9SKees Cook umode_t mode = inode->i_mode; 800800179c9SKees Cook 801800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 802800179c9SKees Cook if (!S_ISREG(mode)) 803800179c9SKees Cook return false; 804800179c9SKees Cook 805800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 806800179c9SKees Cook if (mode & S_ISUID) 807800179c9SKees Cook return false; 808800179c9SKees Cook 809800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 810800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 811800179c9SKees Cook return false; 812800179c9SKees Cook 813800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 814800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 815800179c9SKees Cook return false; 816800179c9SKees Cook 817800179c9SKees Cook return true; 818800179c9SKees Cook } 819800179c9SKees Cook 820800179c9SKees Cook /** 821800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 822800179c9SKees Cook * @link: the source to hardlink from 823800179c9SKees Cook * 824800179c9SKees Cook * Block hardlink when all of: 825800179c9SKees Cook * - sysctl_protected_hardlinks enabled 826800179c9SKees Cook * - fsuid does not match inode 827800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 828800179c9SKees Cook * - not CAP_FOWNER 829800179c9SKees Cook * 830800179c9SKees Cook * Returns 0 if successful, -ve on error. 831800179c9SKees Cook */ 832800179c9SKees Cook static int may_linkat(struct path *link) 833800179c9SKees Cook { 834800179c9SKees Cook const struct cred *cred; 835800179c9SKees Cook struct inode *inode; 836800179c9SKees Cook 837800179c9SKees Cook if (!sysctl_protected_hardlinks) 838800179c9SKees Cook return 0; 839800179c9SKees Cook 840800179c9SKees Cook cred = current_cred(); 841800179c9SKees Cook inode = link->dentry->d_inode; 842800179c9SKees Cook 843800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 844800179c9SKees Cook * otherwise, it must be a safe source. 845800179c9SKees Cook */ 84681abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 847800179c9SKees Cook capable(CAP_FOWNER)) 848800179c9SKees Cook return 0; 849800179c9SKees Cook 850a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 851800179c9SKees Cook return -EPERM; 852800179c9SKees Cook } 853800179c9SKees Cook 854def4af30SAl Viro static __always_inline int 855574197e0SAl Viro follow_link(struct path *link, struct nameidata *nd, void **p) 8561da177e4SLinus Torvalds { 8577b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8586d7b5aaeSAl Viro int error; 8596d7b5aaeSAl Viro char *s; 8601da177e4SLinus Torvalds 861844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 862844a3917SAl Viro 8630e794589SAl Viro if (link->mnt == nd->path.mnt) 8640e794589SAl Viro mntget(link->mnt); 8650e794589SAl Viro 8666d7b5aaeSAl Viro error = -ELOOP; 8676d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8686d7b5aaeSAl Viro goto out_put_nd_path; 8696d7b5aaeSAl Viro 870574197e0SAl Viro cond_resched(); 871574197e0SAl Viro current->total_link_count++; 872574197e0SAl Viro 87368ac1234SAl Viro touch_atime(link); 8741da177e4SLinus Torvalds nd_set_link(nd, NULL); 875cd4e91d3SAl Viro 87636f3b4f6SAl Viro error = security_inode_follow_link(link->dentry, nd); 8776d7b5aaeSAl Viro if (error) 8786d7b5aaeSAl Viro goto out_put_nd_path; 87936f3b4f6SAl Viro 88086acdca1SAl Viro nd->last_type = LAST_BIND; 881def4af30SAl Viro *p = dentry->d_inode->i_op->follow_link(dentry, nd); 882def4af30SAl Viro error = PTR_ERR(*p); 8836d7b5aaeSAl Viro if (IS_ERR(*p)) 884408ef013SChristoph Hellwig goto out_put_nd_path; 8856d7b5aaeSAl Viro 886cc314eefSLinus Torvalds error = 0; 8876d7b5aaeSAl Viro s = nd_get_link(nd); 8886d7b5aaeSAl Viro if (s) { 889443ed254SAl Viro if (unlikely(IS_ERR(s))) { 890443ed254SAl Viro path_put(&nd->path); 891443ed254SAl Viro put_link(nd, link, *p); 892443ed254SAl Viro return PTR_ERR(s); 893443ed254SAl Viro } 894443ed254SAl Viro if (*s == '/') { 8957bd88377SAl Viro if (!nd->root.mnt) 896443ed254SAl Viro set_root(nd); 897443ed254SAl Viro path_put(&nd->path); 898443ed254SAl Viro nd->path = nd->root; 899443ed254SAl Viro path_get(&nd->root); 900443ed254SAl Viro nd->flags |= LOOKUP_JUMPED; 901443ed254SAl Viro } 902443ed254SAl Viro nd->inode = nd->path.dentry->d_inode; 903443ed254SAl Viro error = link_path_walk(s, nd); 9046d7b5aaeSAl Viro if (unlikely(error)) 9056d7b5aaeSAl Viro put_link(nd, link, *p); 906b5fb63c1SChristoph Hellwig } 9076d7b5aaeSAl Viro 9086d7b5aaeSAl Viro return error; 9096d7b5aaeSAl Viro 9106d7b5aaeSAl Viro out_put_nd_path: 91198f6ef64SArnd Bergmann *p = NULL; 9126d7b5aaeSAl Viro path_put(&nd->path); 9136d7b5aaeSAl Viro path_put(link); 9141da177e4SLinus Torvalds return error; 9151da177e4SLinus Torvalds } 9161da177e4SLinus Torvalds 91731e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 91831e6b01fSNick Piggin { 9190714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9200714a533SAl Viro struct mount *parent; 92131e6b01fSNick Piggin struct dentry *mountpoint; 92231e6b01fSNick Piggin 9230714a533SAl Viro parent = mnt->mnt_parent; 9240714a533SAl Viro if (&parent->mnt == path->mnt) 92531e6b01fSNick Piggin return 0; 926a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 92731e6b01fSNick Piggin path->dentry = mountpoint; 9280714a533SAl Viro path->mnt = &parent->mnt; 92931e6b01fSNick Piggin return 1; 93031e6b01fSNick Piggin } 93131e6b01fSNick Piggin 932f015f126SDavid Howells /* 933f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 934f015f126SDavid Howells * 935f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 936f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 937f015f126SDavid Howells * Up is towards /. 938f015f126SDavid Howells * 939f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 940f015f126SDavid Howells * root. 941f015f126SDavid Howells */ 942bab77ebfSAl Viro int follow_up(struct path *path) 9431da177e4SLinus Torvalds { 9440714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9450714a533SAl Viro struct mount *parent; 9461da177e4SLinus Torvalds struct dentry *mountpoint; 94799b7db7bSNick Piggin 94848a066e7SAl Viro read_seqlock_excl(&mount_lock); 9490714a533SAl Viro parent = mnt->mnt_parent; 9503c0a6163SAl Viro if (parent == mnt) { 95148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9521da177e4SLinus Torvalds return 0; 9531da177e4SLinus Torvalds } 9540714a533SAl Viro mntget(&parent->mnt); 955a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 95648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 957bab77ebfSAl Viro dput(path->dentry); 958bab77ebfSAl Viro path->dentry = mountpoint; 959bab77ebfSAl Viro mntput(path->mnt); 9600714a533SAl Viro path->mnt = &parent->mnt; 9611da177e4SLinus Torvalds return 1; 9621da177e4SLinus Torvalds } 9634d359507SAl Viro EXPORT_SYMBOL(follow_up); 9641da177e4SLinus Torvalds 965b5c84bf6SNick Piggin /* 9669875cf80SDavid Howells * Perform an automount 9679875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9689875cf80SDavid Howells * were called with. 9691da177e4SLinus Torvalds */ 9709875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9719875cf80SDavid Howells bool *need_mntput) 97231e6b01fSNick Piggin { 9739875cf80SDavid Howells struct vfsmount *mnt; 974ea5b778aSDavid Howells int err; 9759875cf80SDavid Howells 9769875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9779875cf80SDavid Howells return -EREMOTE; 9789875cf80SDavid Howells 9790ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9800ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9810ec26fd0SMiklos Szeredi * the name. 9820ec26fd0SMiklos Szeredi * 9830ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9845a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9850ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9860ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9870ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9880ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9895a30d8a2SDavid Howells */ 9905a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 991d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9925a30d8a2SDavid Howells path->dentry->d_inode) 9939875cf80SDavid Howells return -EISDIR; 9940ec26fd0SMiklos Szeredi 9959875cf80SDavid Howells current->total_link_count++; 9969875cf80SDavid Howells if (current->total_link_count >= 40) 9979875cf80SDavid Howells return -ELOOP; 9989875cf80SDavid Howells 9999875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10009875cf80SDavid Howells if (IS_ERR(mnt)) { 10019875cf80SDavid Howells /* 10029875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10039875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10049875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10059875cf80SDavid Howells * 10069875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10079875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10089875cf80SDavid Howells * the path is inaccessible and we should say so. 10099875cf80SDavid Howells */ 101049084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 10119875cf80SDavid Howells return -EREMOTE; 10129875cf80SDavid Howells return PTR_ERR(mnt); 101331e6b01fSNick Piggin } 1014ea5b778aSDavid Howells 10159875cf80SDavid Howells if (!mnt) /* mount collision */ 10169875cf80SDavid Howells return 0; 10179875cf80SDavid Howells 10188aef1884SAl Viro if (!*need_mntput) { 10198aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10208aef1884SAl Viro mntget(path->mnt); 10218aef1884SAl Viro *need_mntput = true; 10228aef1884SAl Viro } 102319a167afSAl Viro err = finish_automount(mnt, path); 1024ea5b778aSDavid Howells 1025ea5b778aSDavid Howells switch (err) { 1026ea5b778aSDavid Howells case -EBUSY: 1027ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 102819a167afSAl Viro return 0; 1029ea5b778aSDavid Howells case 0: 10308aef1884SAl Viro path_put(path); 10319875cf80SDavid Howells path->mnt = mnt; 10329875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10339875cf80SDavid Howells return 0; 103419a167afSAl Viro default: 103519a167afSAl Viro return err; 10369875cf80SDavid Howells } 103719a167afSAl Viro 1038ea5b778aSDavid Howells } 10399875cf80SDavid Howells 10409875cf80SDavid Howells /* 10419875cf80SDavid Howells * Handle a dentry that is managed in some way. 1042cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10439875cf80SDavid Howells * - Flagged as mountpoint 10449875cf80SDavid Howells * - Flagged as automount point 10459875cf80SDavid Howells * 10469875cf80SDavid Howells * This may only be called in refwalk mode. 10479875cf80SDavid Howells * 10489875cf80SDavid Howells * Serialization is taken care of in namespace.c 10499875cf80SDavid Howells */ 10509875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10519875cf80SDavid Howells { 10528aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10539875cf80SDavid Howells unsigned managed; 10549875cf80SDavid Howells bool need_mntput = false; 10558aef1884SAl Viro int ret = 0; 10569875cf80SDavid Howells 10579875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10589875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10599875cf80SDavid Howells * the components of that value change under us */ 10609875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10619875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10629875cf80SDavid Howells unlikely(managed != 0)) { 1063cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1064cc53ce53SDavid Howells * being held. */ 1065cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1066cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1067cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10681aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1069cc53ce53SDavid Howells if (ret < 0) 10708aef1884SAl Viro break; 1071cc53ce53SDavid Howells } 1072cc53ce53SDavid Howells 10739875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10749875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10759875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10769875cf80SDavid Howells if (mounted) { 10779875cf80SDavid Howells dput(path->dentry); 10789875cf80SDavid Howells if (need_mntput) 1079463ffb2eSAl Viro mntput(path->mnt); 1080463ffb2eSAl Viro path->mnt = mounted; 1081463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10829875cf80SDavid Howells need_mntput = true; 10839875cf80SDavid Howells continue; 1084463ffb2eSAl Viro } 1085463ffb2eSAl Viro 10869875cf80SDavid Howells /* Something is mounted on this dentry in another 10879875cf80SDavid Howells * namespace and/or whatever was mounted there in this 108848a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 108948a066e7SAl Viro * get it */ 10901da177e4SLinus Torvalds } 10919875cf80SDavid Howells 10929875cf80SDavid Howells /* Handle an automount point */ 10939875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10949875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10959875cf80SDavid Howells if (ret < 0) 10968aef1884SAl Viro break; 10979875cf80SDavid Howells continue; 10989875cf80SDavid Howells } 10999875cf80SDavid Howells 11009875cf80SDavid Howells /* We didn't change the current path point */ 11019875cf80SDavid Howells break; 11029875cf80SDavid Howells } 11038aef1884SAl Viro 11048aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11058aef1884SAl Viro mntput(path->mnt); 11068aef1884SAl Viro if (ret == -EISDIR) 11078aef1884SAl Viro ret = 0; 1108a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 11091da177e4SLinus Torvalds } 11101da177e4SLinus Torvalds 1111cc53ce53SDavid Howells int follow_down_one(struct path *path) 11121da177e4SLinus Torvalds { 11131da177e4SLinus Torvalds struct vfsmount *mounted; 11141da177e4SLinus Torvalds 11151c755af4SAl Viro mounted = lookup_mnt(path); 11161da177e4SLinus Torvalds if (mounted) { 11179393bd07SAl Viro dput(path->dentry); 11189393bd07SAl Viro mntput(path->mnt); 11199393bd07SAl Viro path->mnt = mounted; 11209393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11211da177e4SLinus Torvalds return 1; 11221da177e4SLinus Torvalds } 11231da177e4SLinus Torvalds return 0; 11241da177e4SLinus Torvalds } 11254d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11261da177e4SLinus Torvalds 1127b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 112862a7375eSIan Kent { 1129b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1130b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 113162a7375eSIan Kent } 113262a7375eSIan Kent 11339875cf80SDavid Howells /* 1134287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1135287548e4SAl Viro * we meet a managed dentry that would need blocking. 11369875cf80SDavid Howells */ 11379875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1138287548e4SAl Viro struct inode **inode) 11399875cf80SDavid Howells { 114062a7375eSIan Kent for (;;) { 1141c7105365SAl Viro struct mount *mounted; 114262a7375eSIan Kent /* 114362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 114462a7375eSIan Kent * that wants to block transit. 114562a7375eSIan Kent */ 1146b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1147b8faf035SNeilBrown case -ECHILD: 1148b8faf035SNeilBrown default: 1149ab90911fSDavid Howells return false; 1150b8faf035SNeilBrown case -EISDIR: 1151b8faf035SNeilBrown return true; 1152b8faf035SNeilBrown case 0: 1153b8faf035SNeilBrown break; 1154b8faf035SNeilBrown } 115562a7375eSIan Kent 115662a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1157b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 115862a7375eSIan Kent 1159474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11609875cf80SDavid Howells if (!mounted) 11619875cf80SDavid Howells break; 1162c7105365SAl Viro path->mnt = &mounted->mnt; 1163c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1164a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11659875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 116659430262SLinus Torvalds /* 116759430262SLinus Torvalds * Update the inode too. We don't need to re-check the 116859430262SLinus Torvalds * dentry sequence number here after this d_inode read, 116959430262SLinus Torvalds * because a mount-point is always pinned. 117059430262SLinus Torvalds */ 117159430262SLinus Torvalds *inode = path->dentry->d_inode; 11729875cf80SDavid Howells } 1173f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1174b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1175287548e4SAl Viro } 1176287548e4SAl Viro 117731e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 117831e6b01fSNick Piggin { 11794023bfc9SAl Viro struct inode *inode = nd->inode; 11807bd88377SAl Viro if (!nd->root.mnt) 118131e6b01fSNick Piggin set_root_rcu(nd); 118231e6b01fSNick Piggin 118331e6b01fSNick Piggin while (1) { 118431e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 118531e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 118631e6b01fSNick Piggin break; 118731e6b01fSNick Piggin } 118831e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 118931e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 119031e6b01fSNick Piggin struct dentry *parent = old->d_parent; 119131e6b01fSNick Piggin unsigned seq; 119231e6b01fSNick Piggin 11934023bfc9SAl Viro inode = parent->d_inode; 119431e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 119531e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1196ef7562d5SAl Viro goto failed; 119731e6b01fSNick Piggin nd->path.dentry = parent; 119831e6b01fSNick Piggin nd->seq = seq; 119931e6b01fSNick Piggin break; 120031e6b01fSNick Piggin } 120131e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 120231e6b01fSNick Piggin break; 12034023bfc9SAl Viro inode = nd->path.dentry->d_inode; 120431e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 120531e6b01fSNick Piggin } 1206b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1207b37199e6SAl Viro struct mount *mounted; 1208b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1209b37199e6SAl Viro if (!mounted) 1210b37199e6SAl Viro break; 1211b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1212b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12134023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1214b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1215f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1216b37199e6SAl Viro goto failed; 1217b37199e6SAl Viro } 12184023bfc9SAl Viro nd->inode = inode; 121931e6b01fSNick Piggin return 0; 1220ef7562d5SAl Viro 1221ef7562d5SAl Viro failed: 1222ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 12235b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1224ef7562d5SAl Viro nd->root.mnt = NULL; 12258b61e74fSAl Viro rcu_read_unlock(); 1226ef7562d5SAl Viro return -ECHILD; 122731e6b01fSNick Piggin } 122831e6b01fSNick Piggin 12299875cf80SDavid Howells /* 1230cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1231cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1232cc53ce53SDavid Howells * caller is permitted to proceed or not. 1233cc53ce53SDavid Howells */ 12347cc90cc3SAl Viro int follow_down(struct path *path) 1235cc53ce53SDavid Howells { 1236cc53ce53SDavid Howells unsigned managed; 1237cc53ce53SDavid Howells int ret; 1238cc53ce53SDavid Howells 1239cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1240cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1241cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1242cc53ce53SDavid Howells * being held. 1243cc53ce53SDavid Howells * 1244cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1245cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1246cc53ce53SDavid Howells * other than its daemon the right to mount on its 1247cc53ce53SDavid Howells * superstructure. 1248cc53ce53SDavid Howells * 1249cc53ce53SDavid Howells * The filesystem may sleep at this point. 1250cc53ce53SDavid Howells */ 1251cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1252cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1253cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1254ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12551aed3e42SAl Viro path->dentry, false); 1256cc53ce53SDavid Howells if (ret < 0) 1257cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1258cc53ce53SDavid Howells } 1259cc53ce53SDavid Howells 1260cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1261cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1262cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1263cc53ce53SDavid Howells if (!mounted) 1264cc53ce53SDavid Howells break; 1265cc53ce53SDavid Howells dput(path->dentry); 1266cc53ce53SDavid Howells mntput(path->mnt); 1267cc53ce53SDavid Howells path->mnt = mounted; 1268cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1269cc53ce53SDavid Howells continue; 1270cc53ce53SDavid Howells } 1271cc53ce53SDavid Howells 1272cc53ce53SDavid Howells /* Don't handle automount points here */ 1273cc53ce53SDavid Howells break; 1274cc53ce53SDavid Howells } 1275cc53ce53SDavid Howells return 0; 1276cc53ce53SDavid Howells } 12774d359507SAl Viro EXPORT_SYMBOL(follow_down); 1278cc53ce53SDavid Howells 1279cc53ce53SDavid Howells /* 12809875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12819875cf80SDavid Howells */ 12829875cf80SDavid Howells static void follow_mount(struct path *path) 12839875cf80SDavid Howells { 12849875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12859875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12869875cf80SDavid Howells if (!mounted) 12879875cf80SDavid Howells break; 12889875cf80SDavid Howells dput(path->dentry); 12899875cf80SDavid Howells mntput(path->mnt); 12909875cf80SDavid Howells path->mnt = mounted; 12919875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12929875cf80SDavid Howells } 12939875cf80SDavid Howells } 12949875cf80SDavid Howells 129531e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12961da177e4SLinus Torvalds { 12977bd88377SAl Viro if (!nd->root.mnt) 12982a737871SAl Viro set_root(nd); 1299e518ddb7SAndreas Mohr 13001da177e4SLinus Torvalds while(1) { 13014ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13021da177e4SLinus Torvalds 13032a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13042a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13051da177e4SLinus Torvalds break; 13061da177e4SLinus Torvalds } 13074ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13083088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13093088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13101da177e4SLinus Torvalds dput(old); 13111da177e4SLinus Torvalds break; 13121da177e4SLinus Torvalds } 13133088dd70SAl Viro if (!follow_up(&nd->path)) 13141da177e4SLinus Torvalds break; 13151da177e4SLinus Torvalds } 131679ed0226SAl Viro follow_mount(&nd->path); 131731e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13181da177e4SLinus Torvalds } 13191da177e4SLinus Torvalds 13201da177e4SLinus Torvalds /* 1321bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1322bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1323bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1324bad61189SMiklos Szeredi * 1325bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1326baa03890SNick Piggin */ 1327bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1328201f956eSAl Viro unsigned int flags, bool *need_lookup) 1329baa03890SNick Piggin { 1330baa03890SNick Piggin struct dentry *dentry; 1331bad61189SMiklos Szeredi int error; 1332baa03890SNick Piggin 1333bad61189SMiklos Szeredi *need_lookup = false; 1334bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1335bad61189SMiklos Szeredi if (dentry) { 133639e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1337201f956eSAl Viro error = d_revalidate(dentry, flags); 1338bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1339bad61189SMiklos Szeredi if (error < 0) { 1340bad61189SMiklos Szeredi dput(dentry); 1341bad61189SMiklos Szeredi return ERR_PTR(error); 13425542aa2fSEric W. Biederman } else { 13435542aa2fSEric W. Biederman d_invalidate(dentry); 1344bad61189SMiklos Szeredi dput(dentry); 1345bad61189SMiklos Szeredi dentry = NULL; 1346bad61189SMiklos Szeredi } 1347bad61189SMiklos Szeredi } 1348bad61189SMiklos Szeredi } 1349bad61189SMiklos Szeredi } 1350baa03890SNick Piggin 1351bad61189SMiklos Szeredi if (!dentry) { 1352bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1353baa03890SNick Piggin if (unlikely(!dentry)) 1354baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1355baa03890SNick Piggin 1356bad61189SMiklos Szeredi *need_lookup = true; 1357baa03890SNick Piggin } 1358baa03890SNick Piggin return dentry; 1359baa03890SNick Piggin } 1360baa03890SNick Piggin 1361baa03890SNick Piggin /* 136213a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 136313a2c3beSJ. Bruce Fields * unhashed. 1364bad61189SMiklos Szeredi * 1365bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 136644396f4bSJosef Bacik */ 1367bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 136872bd866aSAl Viro unsigned int flags) 136944396f4bSJosef Bacik { 137044396f4bSJosef Bacik struct dentry *old; 137144396f4bSJosef Bacik 137244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1373bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1374e188dc02SMiklos Szeredi dput(dentry); 137544396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1376e188dc02SMiklos Szeredi } 137744396f4bSJosef Bacik 137872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 137944396f4bSJosef Bacik if (unlikely(old)) { 138044396f4bSJosef Bacik dput(dentry); 138144396f4bSJosef Bacik dentry = old; 138244396f4bSJosef Bacik } 138344396f4bSJosef Bacik return dentry; 138444396f4bSJosef Bacik } 138544396f4bSJosef Bacik 1386a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 138772bd866aSAl Viro struct dentry *base, unsigned int flags) 1388a3255546SAl Viro { 1389bad61189SMiklos Szeredi bool need_lookup; 1390a3255546SAl Viro struct dentry *dentry; 1391a3255546SAl Viro 139272bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1393bad61189SMiklos Szeredi if (!need_lookup) 1394a3255546SAl Viro return dentry; 1395bad61189SMiklos Szeredi 139672bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1397a3255546SAl Viro } 1398a3255546SAl Viro 139944396f4bSJosef Bacik /* 14001da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14011da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14021da177e4SLinus Torvalds * It _is_ time-critical. 14031da177e4SLinus Torvalds */ 1404e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 140531e6b01fSNick Piggin struct path *path, struct inode **inode) 14061da177e4SLinus Torvalds { 14074ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 140831e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14095a18fff2SAl Viro int need_reval = 1; 14105a18fff2SAl Viro int status = 1; 14119875cf80SDavid Howells int err; 14129875cf80SDavid Howells 14133cac260aSAl Viro /* 1414b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1415b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1416b04f784eSNick Piggin * do the non-racy lookup, below. 1417b04f784eSNick Piggin */ 141831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 141931e6b01fSNick Piggin unsigned seq; 1420da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14215a18fff2SAl Viro if (!dentry) 14225a18fff2SAl Viro goto unlazy; 14235a18fff2SAl Viro 142412f8ad4bSLinus Torvalds /* 142512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 142612f8ad4bSLinus Torvalds * the dentry name information from lookup. 142712f8ad4bSLinus Torvalds */ 142812f8ad4bSLinus Torvalds *inode = dentry->d_inode; 142912f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 143012f8ad4bSLinus Torvalds return -ECHILD; 143112f8ad4bSLinus Torvalds 143212f8ad4bSLinus Torvalds /* 143312f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 143412f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 143512f8ad4bSLinus Torvalds * 143612f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 143712f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 143812f8ad4bSLinus Torvalds */ 143931e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 144031e6b01fSNick Piggin return -ECHILD; 144131e6b01fSNick Piggin nd->seq = seq; 14425a18fff2SAl Viro 144324643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14444ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14455a18fff2SAl Viro if (unlikely(status <= 0)) { 14465a18fff2SAl Viro if (status != -ECHILD) 14475a18fff2SAl Viro need_reval = 0; 14485a18fff2SAl Viro goto unlazy; 14495a18fff2SAl Viro } 145024643087SAl Viro } 145131e6b01fSNick Piggin path->mnt = mnt; 145231e6b01fSNick Piggin path->dentry = dentry; 1453b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14549875cf80SDavid Howells return 0; 14555a18fff2SAl Viro unlazy: 145619660af7SAl Viro if (unlazy_walk(nd, dentry)) 14575a18fff2SAl Viro return -ECHILD; 14585a18fff2SAl Viro } else { 1459e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 146024643087SAl Viro } 14615a18fff2SAl Viro 146281e6f520SAl Viro if (unlikely(!dentry)) 146381e6f520SAl Viro goto need_lookup; 14645a18fff2SAl Viro 14655a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14664ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14675a18fff2SAl Viro if (unlikely(status <= 0)) { 14685a18fff2SAl Viro if (status < 0) { 14695a18fff2SAl Viro dput(dentry); 14705a18fff2SAl Viro return status; 14715a18fff2SAl Viro } 14725542aa2fSEric W. Biederman d_invalidate(dentry); 14735a18fff2SAl Viro dput(dentry); 147481e6f520SAl Viro goto need_lookup; 14755a18fff2SAl Viro } 1476697f514dSMiklos Szeredi 14771da177e4SLinus Torvalds path->mnt = mnt; 14781da177e4SLinus Torvalds path->dentry = dentry; 14799875cf80SDavid Howells err = follow_managed(path, nd->flags); 148089312214SIan Kent if (unlikely(err < 0)) { 148189312214SIan Kent path_put_conditional(path, nd); 14829875cf80SDavid Howells return err; 148389312214SIan Kent } 1484a3fbbde7SAl Viro if (err) 1485a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 148631e6b01fSNick Piggin *inode = path->dentry->d_inode; 14871da177e4SLinus Torvalds return 0; 148881e6f520SAl Viro 148981e6f520SAl Viro need_lookup: 1490697f514dSMiklos Szeredi return 1; 1491697f514dSMiklos Szeredi } 1492697f514dSMiklos Szeredi 1493697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1494cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1495697f514dSMiklos Szeredi { 1496697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1497697f514dSMiklos Szeredi int err; 1498697f514dSMiklos Szeredi 1499697f514dSMiklos Szeredi parent = nd->path.dentry; 150081e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 150181e6f520SAl Viro 150281e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1503cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 150481e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 150581e6f520SAl Viro if (IS_ERR(dentry)) 150681e6f520SAl Viro return PTR_ERR(dentry); 1507697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1508697f514dSMiklos Szeredi path->dentry = dentry; 1509697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1510697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1511697f514dSMiklos Szeredi path_put_conditional(path, nd); 1512697f514dSMiklos Szeredi return err; 1513697f514dSMiklos Szeredi } 1514697f514dSMiklos Szeredi if (err) 1515697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1516697f514dSMiklos Szeredi return 0; 15171da177e4SLinus Torvalds } 15181da177e4SLinus Torvalds 151952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 152052094c8aSAl Viro { 152152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15224ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 152352094c8aSAl Viro if (err != -ECHILD) 152452094c8aSAl Viro return err; 152519660af7SAl Viro if (unlazy_walk(nd, NULL)) 152652094c8aSAl Viro return -ECHILD; 152752094c8aSAl Viro } 15284ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152952094c8aSAl Viro } 153052094c8aSAl Viro 15319856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15329856fa1bSAl Viro { 15339856fa1bSAl Viro if (type == LAST_DOTDOT) { 15349856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15359856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15369856fa1bSAl Viro return -ECHILD; 15379856fa1bSAl Viro } else 15389856fa1bSAl Viro follow_dotdot(nd); 15399856fa1bSAl Viro } 15409856fa1bSAl Viro return 0; 15419856fa1bSAl Viro } 15429856fa1bSAl Viro 1543951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1544951361f9SAl Viro { 1545951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1546951361f9SAl Viro path_put(&nd->path); 1547951361f9SAl Viro } else { 1548951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15495b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1550951361f9SAl Viro nd->root.mnt = NULL; 15518b61e74fSAl Viro rcu_read_unlock(); 1552951361f9SAl Viro } 1553951361f9SAl Viro } 1554951361f9SAl Viro 15553ddcd056SLinus Torvalds /* 15563ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15573ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15583ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15593ddcd056SLinus Torvalds * for the common case. 15603ddcd056SLinus Torvalds */ 1561b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15623ddcd056SLinus Torvalds { 1563b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15643ddcd056SLinus Torvalds } 15653ddcd056SLinus Torvalds 1566ce57dfc1SAl Viro static inline int walk_component(struct nameidata *nd, struct path *path, 156721b9b073SAl Viro int follow) 1568ce57dfc1SAl Viro { 1569ce57dfc1SAl Viro struct inode *inode; 1570ce57dfc1SAl Viro int err; 1571ce57dfc1SAl Viro /* 1572ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1573ce57dfc1SAl Viro * to be able to know about the current root directory and 1574ce57dfc1SAl Viro * parent relationships. 1575ce57dfc1SAl Viro */ 157621b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 157721b9b073SAl Viro return handle_dots(nd, nd->last_type); 1578e97cdc87SAl Viro err = lookup_fast(nd, path, &inode); 1579ce57dfc1SAl Viro if (unlikely(err)) { 1580697f514dSMiklos Szeredi if (err < 0) 1581697f514dSMiklos Szeredi goto out_err; 1582697f514dSMiklos Szeredi 1583cc2a5271SAl Viro err = lookup_slow(nd, path); 1584697f514dSMiklos Szeredi if (err < 0) 1585697f514dSMiklos Szeredi goto out_err; 1586697f514dSMiklos Szeredi 1587697f514dSMiklos Szeredi inode = path->dentry->d_inode; 1588ce57dfc1SAl Viro } 1589697f514dSMiklos Szeredi err = -ENOENT; 159022213318SAl Viro if (!inode || d_is_negative(path->dentry)) 1591697f514dSMiklos Szeredi goto out_path_put; 1592697f514dSMiklos Szeredi 1593b18825a7SDavid Howells if (should_follow_link(path->dentry, follow)) { 159419660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 159519660af7SAl Viro if (unlikely(unlazy_walk(nd, path->dentry))) { 1596697f514dSMiklos Szeredi err = -ECHILD; 1597697f514dSMiklos Szeredi goto out_err; 159819660af7SAl Viro } 159919660af7SAl Viro } 1600ce57dfc1SAl Viro BUG_ON(inode != path->dentry->d_inode); 1601ce57dfc1SAl Viro return 1; 1602ce57dfc1SAl Viro } 1603ce57dfc1SAl Viro path_to_nameidata(path, nd); 1604ce57dfc1SAl Viro nd->inode = inode; 1605ce57dfc1SAl Viro return 0; 1606697f514dSMiklos Szeredi 1607697f514dSMiklos Szeredi out_path_put: 1608697f514dSMiklos Szeredi path_to_nameidata(path, nd); 1609697f514dSMiklos Szeredi out_err: 1610697f514dSMiklos Szeredi terminate_walk(nd); 1611697f514dSMiklos Szeredi return err; 1612ce57dfc1SAl Viro } 1613ce57dfc1SAl Viro 16141da177e4SLinus Torvalds /* 1615b356379aSAl Viro * This limits recursive symlink follows to 8, while 1616b356379aSAl Viro * limiting consecutive symlinks to 40. 1617b356379aSAl Viro * 1618b356379aSAl Viro * Without that kind of total limit, nasty chains of consecutive 1619b356379aSAl Viro * symlinks can cause almost arbitrarily long lookups. 1620b356379aSAl Viro */ 1621b356379aSAl Viro static inline int nested_symlink(struct path *path, struct nameidata *nd) 1622b356379aSAl Viro { 1623b356379aSAl Viro int res; 1624b356379aSAl Viro 1625b356379aSAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 1626b356379aSAl Viro path_put_conditional(path, nd); 1627b356379aSAl Viro path_put(&nd->path); 1628b356379aSAl Viro return -ELOOP; 1629b356379aSAl Viro } 16301a4022f8SErez Zadok BUG_ON(nd->depth >= MAX_NESTED_LINKS); 1631b356379aSAl Viro 1632b356379aSAl Viro nd->depth++; 1633b356379aSAl Viro current->link_count++; 1634b356379aSAl Viro 1635b356379aSAl Viro do { 1636b356379aSAl Viro struct path link = *path; 1637b356379aSAl Viro void *cookie; 1638574197e0SAl Viro 1639574197e0SAl Viro res = follow_link(&link, nd, &cookie); 16406d7b5aaeSAl Viro if (res) 16416d7b5aaeSAl Viro break; 164221b9b073SAl Viro res = walk_component(nd, path, LOOKUP_FOLLOW); 1643574197e0SAl Viro put_link(nd, &link, cookie); 1644b356379aSAl Viro } while (res > 0); 1645b356379aSAl Viro 1646b356379aSAl Viro current->link_count--; 1647b356379aSAl Viro nd->depth--; 1648b356379aSAl Viro return res; 1649b356379aSAl Viro } 1650b356379aSAl Viro 1651b356379aSAl Viro /* 1652bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1653bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1654bfcfaa77SLinus Torvalds * 1655bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1656bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1657bfcfaa77SLinus Torvalds * fast. 1658bfcfaa77SLinus Torvalds * 1659bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1660bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1661bfcfaa77SLinus Torvalds * crossing operation. 1662bfcfaa77SLinus Torvalds * 1663bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1664bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1665bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1666bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1667bfcfaa77SLinus Torvalds */ 1668bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1669bfcfaa77SLinus Torvalds 1670f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1671bfcfaa77SLinus Torvalds 1672f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1673bfcfaa77SLinus Torvalds 1674bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1675bfcfaa77SLinus Torvalds { 167699d263d4SLinus Torvalds return hash_64(hash, 32); 1677bfcfaa77SLinus Torvalds } 1678bfcfaa77SLinus Torvalds 1679bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1680bfcfaa77SLinus Torvalds 1681bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1682bfcfaa77SLinus Torvalds 1683bfcfaa77SLinus Torvalds #endif 1684bfcfaa77SLinus Torvalds 1685bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1686bfcfaa77SLinus Torvalds { 1687bfcfaa77SLinus Torvalds unsigned long a, mask; 1688bfcfaa77SLinus Torvalds unsigned long hash = 0; 1689bfcfaa77SLinus Torvalds 1690bfcfaa77SLinus Torvalds for (;;) { 1691e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1692bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1693bfcfaa77SLinus Torvalds break; 1694bfcfaa77SLinus Torvalds hash += a; 1695f132c5beSAl Viro hash *= 9; 1696bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1697bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1698bfcfaa77SLinus Torvalds if (!len) 1699bfcfaa77SLinus Torvalds goto done; 1700bfcfaa77SLinus Torvalds } 1701a5c21dceSWill Deacon mask = bytemask_from_count(len); 1702bfcfaa77SLinus Torvalds hash += mask & a; 1703bfcfaa77SLinus Torvalds done: 1704bfcfaa77SLinus Torvalds return fold_hash(hash); 1705bfcfaa77SLinus Torvalds } 1706bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1707bfcfaa77SLinus Torvalds 1708bfcfaa77SLinus Torvalds /* 1709bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1710d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1711bfcfaa77SLinus Torvalds */ 1712d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1713bfcfaa77SLinus Torvalds { 171436126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 171536126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1716bfcfaa77SLinus Torvalds 1717bfcfaa77SLinus Torvalds hash = a = 0; 1718bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1719bfcfaa77SLinus Torvalds do { 1720bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1721bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1722e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 172336126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 172436126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1725bfcfaa77SLinus Torvalds 172636126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 172736126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172836126f8fSLinus Torvalds 172936126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 173036126f8fSLinus Torvalds 173136126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17329226b5b4SLinus Torvalds len += find_zero(mask); 1733d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1734bfcfaa77SLinus Torvalds } 1735bfcfaa77SLinus Torvalds 1736bfcfaa77SLinus Torvalds #else 1737bfcfaa77SLinus Torvalds 17380145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17390145acc2SLinus Torvalds { 17400145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17410145acc2SLinus Torvalds while (len--) 17420145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17430145acc2SLinus Torvalds return end_name_hash(hash); 17440145acc2SLinus Torvalds } 1745ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17460145acc2SLinus Torvalds 17473ddcd056SLinus Torvalds /* 1748200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1749200e9ef7SLinus Torvalds * one character. 1750200e9ef7SLinus Torvalds */ 1751d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1752200e9ef7SLinus Torvalds { 1753200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1754200e9ef7SLinus Torvalds unsigned long len = 0, c; 1755200e9ef7SLinus Torvalds 1756200e9ef7SLinus Torvalds c = (unsigned char)*name; 1757200e9ef7SLinus Torvalds do { 1758200e9ef7SLinus Torvalds len++; 1759200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1760200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1761200e9ef7SLinus Torvalds } while (c && c != '/'); 1762d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1763200e9ef7SLinus Torvalds } 1764200e9ef7SLinus Torvalds 1765bfcfaa77SLinus Torvalds #endif 1766bfcfaa77SLinus Torvalds 1767200e9ef7SLinus Torvalds /* 17681da177e4SLinus Torvalds * Name resolution. 1769ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1770ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17711da177e4SLinus Torvalds * 1772ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1773ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17741da177e4SLinus Torvalds */ 17756de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17761da177e4SLinus Torvalds { 17771da177e4SLinus Torvalds struct path next; 17781da177e4SLinus Torvalds int err; 17791da177e4SLinus Torvalds 17801da177e4SLinus Torvalds while (*name=='/') 17811da177e4SLinus Torvalds name++; 17821da177e4SLinus Torvalds if (!*name) 1783086e183aSAl Viro return 0; 17841da177e4SLinus Torvalds 17851da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17861da177e4SLinus Torvalds for(;;) { 1787d6bb3e90SLinus Torvalds u64 hash_len; 1788fe479a58SAl Viro int type; 17891da177e4SLinus Torvalds 179052094c8aSAl Viro err = may_lookup(nd); 17911da177e4SLinus Torvalds if (err) 17921da177e4SLinus Torvalds break; 17931da177e4SLinus Torvalds 1794d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17951da177e4SLinus Torvalds 1796fe479a58SAl Viro type = LAST_NORM; 1797d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1798fe479a58SAl Viro case 2: 1799200e9ef7SLinus Torvalds if (name[1] == '.') { 1800fe479a58SAl Viro type = LAST_DOTDOT; 180116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 180216c2cd71SAl Viro } 1803fe479a58SAl Viro break; 1804fe479a58SAl Viro case 1: 1805fe479a58SAl Viro type = LAST_DOT; 1806fe479a58SAl Viro } 18075a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18085a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18105a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1811a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1812da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18135a202bcdSAl Viro if (err < 0) 18145a202bcdSAl Viro break; 1815d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1816d6bb3e90SLinus Torvalds name = this.name; 18175a202bcdSAl Viro } 18185a202bcdSAl Viro } 1819fe479a58SAl Viro 1820d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1821d6bb3e90SLinus Torvalds nd->last.name = name; 18225f4a6a69SAl Viro nd->last_type = type; 18235f4a6a69SAl Viro 1824d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1825d6bb3e90SLinus Torvalds if (!*name) 18265f4a6a69SAl Viro return 0; 1827200e9ef7SLinus Torvalds /* 1828200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1829200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1830200e9ef7SLinus Torvalds */ 1831200e9ef7SLinus Torvalds do { 1832d6bb3e90SLinus Torvalds name++; 1833d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1834d6bb3e90SLinus Torvalds if (!*name) 18355f4a6a69SAl Viro return 0; 18365f4a6a69SAl Viro 183721b9b073SAl Viro err = walk_component(nd, &next, LOOKUP_FOLLOW); 1838ce57dfc1SAl Viro if (err < 0) 1839ce57dfc1SAl Viro return err; 1840fe479a58SAl Viro 1841ce57dfc1SAl Viro if (err) { 1842b356379aSAl Viro err = nested_symlink(&next, nd); 18431da177e4SLinus Torvalds if (err) 1844a7472babSAl Viro return err; 184531e6b01fSNick Piggin } 184644b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18473ddcd056SLinus Torvalds err = -ENOTDIR; 18483ddcd056SLinus Torvalds break; 18495f4a6a69SAl Viro } 1850ce57dfc1SAl Viro } 1851951361f9SAl Viro terminate_walk(nd); 18521da177e4SLinus Torvalds return err; 18531da177e4SLinus Torvalds } 18541da177e4SLinus Torvalds 185570e9b357SAl Viro static int path_init(int dfd, const char *name, unsigned int flags, 18565e53084dSAl Viro struct nameidata *nd) 185731e6b01fSNick Piggin { 185831e6b01fSNick Piggin int retval = 0; 185931e6b01fSNick Piggin 186031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1861980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 186231e6b01fSNick Piggin nd->depth = 0; 18635e53084dSAl Viro nd->base = NULL; 18645b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1865b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1866b18825a7SDavid Howells struct inode *inode = root->d_inode; 186773d049a4SAl Viro if (*name) { 186844b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18695b6ca027SAl Viro return -ENOTDIR; 18705b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18715b6ca027SAl Viro if (retval) 18725b6ca027SAl Viro return retval; 187373d049a4SAl Viro } 18745b6ca027SAl Viro nd->path = nd->root; 18755b6ca027SAl Viro nd->inode = inode; 18765b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18778b61e74fSAl Viro rcu_read_lock(); 18785b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 187948a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18805b6ca027SAl Viro } else { 18815b6ca027SAl Viro path_get(&nd->path); 18825b6ca027SAl Viro } 1883d465887fSAl Viro goto done; 18845b6ca027SAl Viro } 18855b6ca027SAl Viro 188631e6b01fSNick Piggin nd->root.mnt = NULL; 188731e6b01fSNick Piggin 188848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 188931e6b01fSNick Piggin if (*name=='/') { 1890e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18918b61e74fSAl Viro rcu_read_lock(); 18927bd88377SAl Viro nd->seq = set_root_rcu(nd); 1893e41f7d4eSAl Viro } else { 1894e41f7d4eSAl Viro set_root(nd); 1895e41f7d4eSAl Viro path_get(&nd->root); 1896e41f7d4eSAl Viro } 189731e6b01fSNick Piggin nd->path = nd->root; 189831e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1899e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 190031e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1901c28cc364SNick Piggin unsigned seq; 190231e6b01fSNick Piggin 19038b61e74fSAl Viro rcu_read_lock(); 190431e6b01fSNick Piggin 1905c28cc364SNick Piggin do { 1906c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 190731e6b01fSNick Piggin nd->path = fs->pwd; 1908c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1909c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1910e41f7d4eSAl Viro } else { 1911e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1912e41f7d4eSAl Viro } 191331e6b01fSNick Piggin } else { 1914582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19152903ff01SAl Viro struct fd f = fdget_raw(dfd); 191631e6b01fSNick Piggin struct dentry *dentry; 191731e6b01fSNick Piggin 19182903ff01SAl Viro if (!f.file) 19192903ff01SAl Viro return -EBADF; 192031e6b01fSNick Piggin 19212903ff01SAl Viro dentry = f.file->f_path.dentry; 192231e6b01fSNick Piggin 1923f52e0c11SAl Viro if (*name) { 192444b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19252903ff01SAl Viro fdput(f); 19262903ff01SAl Viro return -ENOTDIR; 1927f52e0c11SAl Viro } 19282903ff01SAl Viro } 19292903ff01SAl Viro 19302903ff01SAl Viro nd->path = f.file->f_path; 1931e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19329c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19335e53084dSAl Viro nd->base = f.file; 1934c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19358b61e74fSAl Viro rcu_read_lock(); 19365590ff0dSUlrich Drepper } else { 19372903ff01SAl Viro path_get(&nd->path); 19382903ff01SAl Viro fdput(f); 19391da177e4SLinus Torvalds } 1940e41f7d4eSAl Viro } 1941e41f7d4eSAl Viro 194231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19434023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1944d465887fSAl Viro goto done; 19454023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1946d465887fSAl Viro goto done; 19474023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19484023bfc9SAl Viro nd->root.mnt = NULL; 19494023bfc9SAl Viro rcu_read_unlock(); 19504023bfc9SAl Viro return -ECHILD; 1951d465887fSAl Viro done: 1952d465887fSAl Viro current->total_link_count = 0; 1953d465887fSAl Viro return link_path_walk(name, nd); 19549b4a9b14SAl Viro } 19559b4a9b14SAl Viro 1956893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1957893b7775SAl Viro { 1958893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1959893b7775SAl Viro path_put(&nd->root); 1960893b7775SAl Viro nd->root.mnt = NULL; 1961893b7775SAl Viro } 1962893b7775SAl Viro if (unlikely(nd->base)) 1963893b7775SAl Viro fput(nd->base); 19649b4a9b14SAl Viro } 19659b4a9b14SAl Viro 1966bd92d7feSAl Viro static inline int lookup_last(struct nameidata *nd, struct path *path) 1967bd92d7feSAl Viro { 1968bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1969bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1970bd92d7feSAl Viro 1971bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 197221b9b073SAl Viro return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); 1973bd92d7feSAl Viro } 1974bd92d7feSAl Viro 19759b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 1976ee0827cdSAl Viro static int path_lookupat(int dfd, const char *name, 19779b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19789b4a9b14SAl Viro { 1979bd92d7feSAl Viro struct path path; 1980bd92d7feSAl Viro int err; 198131e6b01fSNick Piggin 198231e6b01fSNick Piggin /* 198331e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 198431e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 198531e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 198631e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 198731e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 198831e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 198931e6b01fSNick Piggin * analogue, foo_rcu(). 199031e6b01fSNick Piggin * 199131e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 199231e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 199331e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 199431e6b01fSNick Piggin * be able to complete). 199531e6b01fSNick Piggin */ 1996980f3ea2SAl Viro err = path_init(dfd, name, flags, nd); 1997bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 1998bd92d7feSAl Viro err = lookup_last(nd, &path); 1999bd92d7feSAl Viro while (err > 0) { 2000bd92d7feSAl Viro void *cookie; 2001bd92d7feSAl Viro struct path link = path; 2002800179c9SKees Cook err = may_follow_link(&link, nd); 2003800179c9SKees Cook if (unlikely(err)) 2004800179c9SKees Cook break; 2005bd92d7feSAl Viro nd->flags |= LOOKUP_PARENT; 2006574197e0SAl Viro err = follow_link(&link, nd, &cookie); 20076d7b5aaeSAl Viro if (err) 20086d7b5aaeSAl Viro break; 2009bd92d7feSAl Viro err = lookup_last(nd, &path); 2010574197e0SAl Viro put_link(nd, &link, cookie); 2011bd92d7feSAl Viro } 2012bd92d7feSAl Viro } 2013ee0827cdSAl Viro 20149f1fafeeSAl Viro if (!err) 20159f1fafeeSAl Viro err = complete_walk(nd); 2016bd92d7feSAl Viro 2017bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 201844b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2019bd92d7feSAl Viro path_put(&nd->path); 2020bd23a539SAl Viro err = -ENOTDIR; 2021bd92d7feSAl Viro } 2022bd92d7feSAl Viro } 202316c2cd71SAl Viro 2024893b7775SAl Viro path_cleanup(nd); 2025bd92d7feSAl Viro return err; 202631e6b01fSNick Piggin } 202731e6b01fSNick Piggin 2028873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2029873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2030873f1eedSJeff Layton { 2031873f1eedSJeff Layton int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); 2032873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2033873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, flags, nd); 2034873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2035873f1eedSJeff Layton retval = path_lookupat(dfd, name->name, 2036873f1eedSJeff Layton flags | LOOKUP_REVAL, nd); 2037873f1eedSJeff Layton 2038873f1eedSJeff Layton if (likely(!retval)) 2039adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2040873f1eedSJeff Layton return retval; 2041873f1eedSJeff Layton } 2042873f1eedSJeff Layton 2043ee0827cdSAl Viro static int do_path_lookup(int dfd, const char *name, 2044ee0827cdSAl Viro unsigned int flags, struct nameidata *nd) 2045ee0827cdSAl Viro { 204651689104SPaul Moore struct filename *filename = getname_kernel(name); 204751689104SPaul Moore int retval = PTR_ERR(filename); 2048ee0827cdSAl Viro 204951689104SPaul Moore if (!IS_ERR(filename)) { 205051689104SPaul Moore retval = filename_lookup(dfd, filename, flags, nd); 205151689104SPaul Moore putname(filename); 205251689104SPaul Moore } 205351689104SPaul Moore return retval; 20541da177e4SLinus Torvalds } 20551da177e4SLinus Torvalds 205679714f72SAl Viro /* does lookup, returns the object with parent locked */ 205779714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20585590ff0dSUlrich Drepper { 205951689104SPaul Moore struct filename *filename = getname_kernel(name); 206079714f72SAl Viro struct nameidata nd; 206179714f72SAl Viro struct dentry *d; 206251689104SPaul Moore int err; 206351689104SPaul Moore 206451689104SPaul Moore if (IS_ERR(filename)) 206551689104SPaul Moore return ERR_CAST(filename); 206651689104SPaul Moore 206751689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 206851689104SPaul Moore if (err) { 206951689104SPaul Moore d = ERR_PTR(err); 207051689104SPaul Moore goto out; 207151689104SPaul Moore } 207279714f72SAl Viro if (nd.last_type != LAST_NORM) { 207379714f72SAl Viro path_put(&nd.path); 207451689104SPaul Moore d = ERR_PTR(-EINVAL); 207551689104SPaul Moore goto out; 207679714f72SAl Viro } 207779714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20781e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 207979714f72SAl Viro if (IS_ERR(d)) { 208079714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 208179714f72SAl Viro path_put(&nd.path); 208251689104SPaul Moore goto out; 208379714f72SAl Viro } 208479714f72SAl Viro *path = nd.path; 208551689104SPaul Moore out: 208651689104SPaul Moore putname(filename); 208779714f72SAl Viro return d; 20885590ff0dSUlrich Drepper } 20895590ff0dSUlrich Drepper 2090d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2091d1811465SAl Viro { 2092d1811465SAl Viro struct nameidata nd; 2093d1811465SAl Viro int res = do_path_lookup(AT_FDCWD, name, flags, &nd); 2094d1811465SAl Viro if (!res) 2095d1811465SAl Viro *path = nd.path; 2096d1811465SAl Viro return res; 2097d1811465SAl Viro } 20984d359507SAl Viro EXPORT_SYMBOL(kern_path); 2099d1811465SAl Viro 210016f18200SJosef 'Jeff' Sipek /** 210116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 210216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 210316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 210416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 210516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2106e0a01249SAl Viro * @path: pointer to struct path to fill 210716f18200SJosef 'Jeff' Sipek */ 210816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 210916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2110e0a01249SAl Viro struct path *path) 211116f18200SJosef 'Jeff' Sipek { 2112e0a01249SAl Viro struct nameidata nd; 2113e0a01249SAl Viro int err; 2114e0a01249SAl Viro nd.root.dentry = dentry; 2115e0a01249SAl Viro nd.root.mnt = mnt; 2116e0a01249SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21175b6ca027SAl Viro /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ 2118e0a01249SAl Viro err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); 2119e0a01249SAl Viro if (!err) 2120e0a01249SAl Viro *path = nd.path; 2121e0a01249SAl Viro return err; 212216f18200SJosef 'Jeff' Sipek } 21234d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 212416f18200SJosef 'Jeff' Sipek 2125057f6c01SJames Morris /* 2126057f6c01SJames Morris * Restricted form of lookup. Doesn't follow links, single-component only, 2127057f6c01SJames Morris * needs parent already locked. Doesn't follow mounts. 2128057f6c01SJames Morris * SMP-safe. 2129057f6c01SJames Morris */ 2130a244e169SAdrian Bunk static struct dentry *lookup_hash(struct nameidata *nd) 21311da177e4SLinus Torvalds { 213272bd866aSAl Viro return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); 21331da177e4SLinus Torvalds } 21341da177e4SLinus Torvalds 2135eead1911SChristoph Hellwig /** 2136a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2137eead1911SChristoph Hellwig * @name: pathname component to lookup 2138eead1911SChristoph Hellwig * @base: base directory to lookup from 2139eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2140eead1911SChristoph Hellwig * 2141a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 2142a6b91919SRandy Dunlap * not be called by generic code. Also note that by using this function the 2143eead1911SChristoph Hellwig * nameidata argument is passed to the filesystem methods and a filesystem 2144eead1911SChristoph Hellwig * using this helper needs to be prepared for that. 2145eead1911SChristoph Hellwig */ 2146057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2147057f6c01SJames Morris { 2148057f6c01SJames Morris struct qstr this; 21496a96ba54SAl Viro unsigned int c; 2150cda309deSMiklos Szeredi int err; 2151057f6c01SJames Morris 21522f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21532f9092e1SDavid Woodhouse 21546a96ba54SAl Viro this.name = name; 21556a96ba54SAl Viro this.len = len; 21560145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21576a96ba54SAl Viro if (!len) 21586a96ba54SAl Viro return ERR_PTR(-EACCES); 21596a96ba54SAl Viro 216021d8a15aSAl Viro if (unlikely(name[0] == '.')) { 216121d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 216221d8a15aSAl Viro return ERR_PTR(-EACCES); 216321d8a15aSAl Viro } 216421d8a15aSAl Viro 21656a96ba54SAl Viro while (len--) { 21666a96ba54SAl Viro c = *(const unsigned char *)name++; 21676a96ba54SAl Viro if (c == '/' || c == '\0') 21686a96ba54SAl Viro return ERR_PTR(-EACCES); 21696a96ba54SAl Viro } 21705a202bcdSAl Viro /* 21715a202bcdSAl Viro * See if the low-level filesystem might want 21725a202bcdSAl Viro * to use its own hash.. 21735a202bcdSAl Viro */ 21745a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2175da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21765a202bcdSAl Viro if (err < 0) 21775a202bcdSAl Viro return ERR_PTR(err); 21785a202bcdSAl Viro } 2179eead1911SChristoph Hellwig 2180cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2181cda309deSMiklos Szeredi if (err) 2182cda309deSMiklos Szeredi return ERR_PTR(err); 2183cda309deSMiklos Szeredi 218472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2185057f6c01SJames Morris } 21864d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2187057f6c01SJames Morris 21881fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 21891fa1e7f6SAndy Whitcroft struct path *path, int *empty) 21901da177e4SLinus Torvalds { 21912d8f3038SAl Viro struct nameidata nd; 219291a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 21931da177e4SLinus Torvalds int err = PTR_ERR(tmp); 21941da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 21952d8f3038SAl Viro 21962d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 21972d8f3038SAl Viro 2198873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 21991da177e4SLinus Torvalds putname(tmp); 22002d8f3038SAl Viro if (!err) 22012d8f3038SAl Viro *path = nd.path; 22021da177e4SLinus Torvalds } 22031da177e4SLinus Torvalds return err; 22041da177e4SLinus Torvalds } 22051da177e4SLinus Torvalds 22061fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22071fa1e7f6SAndy Whitcroft struct path *path) 22081fa1e7f6SAndy Whitcroft { 2209f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22101fa1e7f6SAndy Whitcroft } 22114d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22121fa1e7f6SAndy Whitcroft 2213873f1eedSJeff Layton /* 2214873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2215873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2216873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2217873f1eedSJeff Layton * path-walking is complete. 2218873f1eedSJeff Layton */ 221991a27b2aSJeff Layton static struct filename * 22209e790bd6SJeff Layton user_path_parent(int dfd, const char __user *path, struct nameidata *nd, 22219e790bd6SJeff Layton unsigned int flags) 22222ad94ae6SAl Viro { 222391a27b2aSJeff Layton struct filename *s = getname(path); 22242ad94ae6SAl Viro int error; 22252ad94ae6SAl Viro 22269e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22279e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22289e790bd6SJeff Layton 22292ad94ae6SAl Viro if (IS_ERR(s)) 223091a27b2aSJeff Layton return s; 22312ad94ae6SAl Viro 22329e790bd6SJeff Layton error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); 223391a27b2aSJeff Layton if (error) { 22342ad94ae6SAl Viro putname(s); 223591a27b2aSJeff Layton return ERR_PTR(error); 223691a27b2aSJeff Layton } 22372ad94ae6SAl Viro 223891a27b2aSJeff Layton return s; 22392ad94ae6SAl Viro } 22402ad94ae6SAl Viro 22418033426eSJeff Layton /** 2242197df04cSAl Viro * mountpoint_last - look up last component for umount 22438033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22448033426eSJeff Layton * @path: pointer to container for result 22458033426eSJeff Layton * 22468033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22478033426eSJeff Layton * need to resolve the path without doing any revalidation. 22488033426eSJeff Layton * 22498033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22508033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22518033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22528033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22538033426eSJeff Layton * bogus and it doesn't exist. 22548033426eSJeff Layton * 22558033426eSJeff Layton * Returns: 22568033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22578033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22588033426eSJeff Layton * put in this case. 22598033426eSJeff Layton * 22608033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22618033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22628033426eSJeff Layton * The nd->path reference will also be put. 22638033426eSJeff Layton * 22648033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22658033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22668033426eSJeff Layton * to the link, and nd->path will *not* be put. 22678033426eSJeff Layton */ 22688033426eSJeff Layton static int 2269197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22708033426eSJeff Layton { 22718033426eSJeff Layton int error = 0; 22728033426eSJeff Layton struct dentry *dentry; 22738033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22748033426eSJeff Layton 227535759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 227635759521SAl Viro if (nd->flags & LOOKUP_RCU) { 227735759521SAl Viro if (unlazy_walk(nd, NULL)) { 22788033426eSJeff Layton error = -ECHILD; 227935759521SAl Viro goto out; 228035759521SAl Viro } 22818033426eSJeff Layton } 22828033426eSJeff Layton 22838033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 22848033426eSJeff Layton 22858033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 22868033426eSJeff Layton error = handle_dots(nd, nd->last_type); 228735759521SAl Viro if (error) 228835759521SAl Viro goto out; 22898033426eSJeff Layton dentry = dget(nd->path.dentry); 229035759521SAl Viro goto done; 22918033426eSJeff Layton } 22928033426eSJeff Layton 22938033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 22948033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 22958033426eSJeff Layton if (!dentry) { 22968033426eSJeff Layton /* 22978033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 22988033426eSJeff Layton * so that means that this dentry is probably a symlink or the 22998033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23008033426eSJeff Layton */ 23018033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23028033426eSJeff Layton if (!dentry) { 23038033426eSJeff Layton error = -ENOMEM; 2304bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 230535759521SAl Viro goto out; 23068033426eSJeff Layton } 230735759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 230835759521SAl Viro error = PTR_ERR(dentry); 2309bcceeebaSDave Jones if (IS_ERR(dentry)) { 2310bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 231135759521SAl Viro goto out; 23128033426eSJeff Layton } 2313bcceeebaSDave Jones } 23148033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23158033426eSJeff Layton 231635759521SAl Viro done: 231722213318SAl Viro if (!dentry->d_inode || d_is_negative(dentry)) { 23188033426eSJeff Layton error = -ENOENT; 23198033426eSJeff Layton dput(dentry); 232035759521SAl Viro goto out; 232135759521SAl Viro } 23228033426eSJeff Layton path->dentry = dentry; 2323295dc39dSVasily Averin path->mnt = nd->path.mnt; 2324b18825a7SDavid Howells if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) 23258033426eSJeff Layton return 1; 2326295dc39dSVasily Averin mntget(path->mnt); 23278033426eSJeff Layton follow_mount(path); 232835759521SAl Viro error = 0; 232935759521SAl Viro out: 23308033426eSJeff Layton terminate_walk(nd); 23318033426eSJeff Layton return error; 23328033426eSJeff Layton } 23338033426eSJeff Layton 23348033426eSJeff Layton /** 2335197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23368033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23378033426eSJeff Layton * @name: full pathname to walk 2338606d6fe3SRandy Dunlap * @path: pointer to container for result 23398033426eSJeff Layton * @flags: lookup flags 23408033426eSJeff Layton * 23418033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2342606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23438033426eSJeff Layton */ 23448033426eSJeff Layton static int 2345197df04cSAl Viro path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) 23468033426eSJeff Layton { 23478033426eSJeff Layton struct nameidata nd; 23488033426eSJeff Layton int err; 23498033426eSJeff Layton 2350980f3ea2SAl Viro err = path_init(dfd, name, flags, &nd); 23518033426eSJeff Layton if (unlikely(err)) 2352115cbfdcSAl Viro goto out; 23538033426eSJeff Layton 2354197df04cSAl Viro err = mountpoint_last(&nd, path); 23558033426eSJeff Layton while (err > 0) { 23568033426eSJeff Layton void *cookie; 23578033426eSJeff Layton struct path link = *path; 23588033426eSJeff Layton err = may_follow_link(&link, &nd); 23598033426eSJeff Layton if (unlikely(err)) 23608033426eSJeff Layton break; 23618033426eSJeff Layton nd.flags |= LOOKUP_PARENT; 23628033426eSJeff Layton err = follow_link(&link, &nd, &cookie); 23638033426eSJeff Layton if (err) 23648033426eSJeff Layton break; 2365197df04cSAl Viro err = mountpoint_last(&nd, path); 23668033426eSJeff Layton put_link(&nd, &link, cookie); 23678033426eSJeff Layton } 23688033426eSJeff Layton out: 2369893b7775SAl Viro path_cleanup(&nd); 23708033426eSJeff Layton return err; 23718033426eSJeff Layton } 23728033426eSJeff Layton 23732d864651SAl Viro static int 23742d864651SAl Viro filename_mountpoint(int dfd, struct filename *s, struct path *path, 23752d864651SAl Viro unsigned int flags) 23762d864651SAl Viro { 2377cbaab2dbSAl Viro int error; 2378cbaab2dbSAl Viro if (IS_ERR(s)) 2379cbaab2dbSAl Viro return PTR_ERR(s); 2380cbaab2dbSAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); 23812d864651SAl Viro if (unlikely(error == -ECHILD)) 23822d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags); 23832d864651SAl Viro if (unlikely(error == -ESTALE)) 23842d864651SAl Viro error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); 23852d864651SAl Viro if (likely(!error)) 23862d864651SAl Viro audit_inode(s, path->dentry, 0); 2387cbaab2dbSAl Viro putname(s); 23882d864651SAl Viro return error; 23892d864651SAl Viro } 23902d864651SAl Viro 23918033426eSJeff Layton /** 2392197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 23938033426eSJeff Layton * @dfd: directory file descriptor 23948033426eSJeff Layton * @name: pathname from userland 23958033426eSJeff Layton * @flags: lookup flags 23968033426eSJeff Layton * @path: pointer to container to hold result 23978033426eSJeff Layton * 23988033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 23998033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24008033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24018033426eSJeff Layton * and avoid revalidating the last component. 24028033426eSJeff Layton * 24038033426eSJeff Layton * Returns 0 and populates "path" on success. 24048033426eSJeff Layton */ 24058033426eSJeff Layton int 2406197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24078033426eSJeff Layton struct path *path) 24088033426eSJeff Layton { 2409cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24108033426eSJeff Layton } 24118033426eSJeff Layton 24122d864651SAl Viro int 24132d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24142d864651SAl Viro unsigned int flags) 24152d864651SAl Viro { 2416cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24172d864651SAl Viro } 24182d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24192d864651SAl Viro 2420cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24211da177e4SLinus Torvalds { 24228e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2423da9592edSDavid Howells 24248e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24251da177e4SLinus Torvalds return 0; 24268e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24271da177e4SLinus Torvalds return 0; 242823adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24291da177e4SLinus Torvalds } 2430cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24311da177e4SLinus Torvalds 24321da177e4SLinus Torvalds /* 24331da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24341da177e4SLinus Torvalds * whether the type of victim is right. 24351da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24361da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24371da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24381da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24391da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24401da177e4SLinus Torvalds * a. be owner of dir, or 24411da177e4SLinus Torvalds * b. be owner of victim, or 24421da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24431da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24441da177e4SLinus Torvalds * links pointing to it. 24451da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24461da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24471da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24481da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24491da177e4SLinus Torvalds * nfs_async_unlink(). 24501da177e4SLinus Torvalds */ 2451b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24521da177e4SLinus Torvalds { 2453b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24541da177e4SLinus Torvalds int error; 24551da177e4SLinus Torvalds 2456b18825a7SDavid Howells if (d_is_negative(victim)) 24571da177e4SLinus Torvalds return -ENOENT; 2458b18825a7SDavid Howells BUG_ON(!inode); 24591da177e4SLinus Torvalds 24601da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24614fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24621da177e4SLinus Torvalds 2463f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24641da177e4SLinus Torvalds if (error) 24651da177e4SLinus Torvalds return error; 24661da177e4SLinus Torvalds if (IS_APPEND(dir)) 24671da177e4SLinus Torvalds return -EPERM; 2468b18825a7SDavid Howells 2469b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2470b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24711da177e4SLinus Torvalds return -EPERM; 24721da177e4SLinus Torvalds if (isdir) { 247344b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24741da177e4SLinus Torvalds return -ENOTDIR; 24751da177e4SLinus Torvalds if (IS_ROOT(victim)) 24761da177e4SLinus Torvalds return -EBUSY; 247744b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24781da177e4SLinus Torvalds return -EISDIR; 24791da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24801da177e4SLinus Torvalds return -ENOENT; 24811da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 24821da177e4SLinus Torvalds return -EBUSY; 24831da177e4SLinus Torvalds return 0; 24841da177e4SLinus Torvalds } 24851da177e4SLinus Torvalds 24861da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 24871da177e4SLinus Torvalds * dir. 24881da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 24891da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 24901da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 24911da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 24921da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 24931da177e4SLinus Torvalds */ 2494a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 24951da177e4SLinus Torvalds { 249614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 24971da177e4SLinus Torvalds if (child->d_inode) 24981da177e4SLinus Torvalds return -EEXIST; 24991da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25001da177e4SLinus Torvalds return -ENOENT; 2501f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25021da177e4SLinus Torvalds } 25031da177e4SLinus Torvalds 25041da177e4SLinus Torvalds /* 25051da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25061da177e4SLinus Torvalds */ 25071da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25081da177e4SLinus Torvalds { 25091da177e4SLinus Torvalds struct dentry *p; 25101da177e4SLinus Torvalds 25111da177e4SLinus Torvalds if (p1 == p2) { 2512f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25131da177e4SLinus Torvalds return NULL; 25141da177e4SLinus Torvalds } 25151da177e4SLinus Torvalds 2516a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25171da177e4SLinus Torvalds 2518e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2519e2761a11SOGAWA Hirofumi if (p) { 2520f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2521f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25221da177e4SLinus Torvalds return p; 25231da177e4SLinus Torvalds } 25241da177e4SLinus Torvalds 2525e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2526e2761a11SOGAWA Hirofumi if (p) { 2527f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2528f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25291da177e4SLinus Torvalds return p; 25301da177e4SLinus Torvalds } 25311da177e4SLinus Torvalds 2532f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2533d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25341da177e4SLinus Torvalds return NULL; 25351da177e4SLinus Torvalds } 25364d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25371da177e4SLinus Torvalds 25381da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25391da177e4SLinus Torvalds { 25401b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25411da177e4SLinus Torvalds if (p1 != p2) { 25421b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2543a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25441da177e4SLinus Torvalds } 25451da177e4SLinus Torvalds } 25464d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25471da177e4SLinus Torvalds 25484acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2549312b63fbSAl Viro bool want_excl) 25501da177e4SLinus Torvalds { 2551a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25521da177e4SLinus Torvalds if (error) 25531da177e4SLinus Torvalds return error; 25541da177e4SLinus Torvalds 2555acfa4380SAl Viro if (!dir->i_op->create) 25561da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25571da177e4SLinus Torvalds mode &= S_IALLUGO; 25581da177e4SLinus Torvalds mode |= S_IFREG; 25591da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25601da177e4SLinus Torvalds if (error) 25611da177e4SLinus Torvalds return error; 2562312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2563a74574aaSStephen Smalley if (!error) 2564f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25651da177e4SLinus Torvalds return error; 25661da177e4SLinus Torvalds } 25674d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25681da177e4SLinus Torvalds 256973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25701da177e4SLinus Torvalds { 25713fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25721da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25731da177e4SLinus Torvalds int error; 25741da177e4SLinus Torvalds 2575bcda7652SAl Viro /* O_PATH? */ 2576bcda7652SAl Viro if (!acc_mode) 2577bcda7652SAl Viro return 0; 2578bcda7652SAl Viro 25791da177e4SLinus Torvalds if (!inode) 25801da177e4SLinus Torvalds return -ENOENT; 25811da177e4SLinus Torvalds 2582c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2583c8fe8f30SChristoph Hellwig case S_IFLNK: 25841da177e4SLinus Torvalds return -ELOOP; 2585c8fe8f30SChristoph Hellwig case S_IFDIR: 2586c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 25871da177e4SLinus Torvalds return -EISDIR; 2588c8fe8f30SChristoph Hellwig break; 2589c8fe8f30SChristoph Hellwig case S_IFBLK: 2590c8fe8f30SChristoph Hellwig case S_IFCHR: 25913fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 25921da177e4SLinus Torvalds return -EACCES; 2593c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2594c8fe8f30SChristoph Hellwig case S_IFIFO: 2595c8fe8f30SChristoph Hellwig case S_IFSOCK: 25961da177e4SLinus Torvalds flag &= ~O_TRUNC; 2597c8fe8f30SChristoph Hellwig break; 25984a3fd211SDave Hansen } 2599b41572e9SDave Hansen 26003fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2601b41572e9SDave Hansen if (error) 2602b41572e9SDave Hansen return error; 26036146f0d5SMimi Zohar 26041da177e4SLinus Torvalds /* 26051da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26061da177e4SLinus Torvalds */ 26071da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26088737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26097715b521SAl Viro return -EPERM; 26101da177e4SLinus Torvalds if (flag & O_TRUNC) 26117715b521SAl Viro return -EPERM; 26121da177e4SLinus Torvalds } 26131da177e4SLinus Torvalds 26141da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26152e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26167715b521SAl Viro return -EPERM; 26171da177e4SLinus Torvalds 2618f3c7691eSJ. Bruce Fields return 0; 26197715b521SAl Viro } 26207715b521SAl Viro 2621e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26227715b521SAl Viro { 2623e1181ee6SJeff Layton struct path *path = &filp->f_path; 26247715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26257715b521SAl Viro int error = get_write_access(inode); 26261da177e4SLinus Torvalds if (error) 26277715b521SAl Viro return error; 26281da177e4SLinus Torvalds /* 26291da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26301da177e4SLinus Torvalds */ 2631d7a06983SJeff Layton error = locks_verify_locked(filp); 2632be6d3e56SKentaro Takeda if (!error) 2633ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26341da177e4SLinus Torvalds if (!error) { 26357715b521SAl Viro error = do_truncate(path->dentry, 0, 2636d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2637e1181ee6SJeff Layton filp); 26381da177e4SLinus Torvalds } 26391da177e4SLinus Torvalds put_write_access(inode); 2640acd0c935SMimi Zohar return error; 26411da177e4SLinus Torvalds } 26421da177e4SLinus Torvalds 2643d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2644d57999e1SDave Hansen { 26458a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26468a5e929dSAl Viro flag--; 2647d57999e1SDave Hansen return flag; 2648d57999e1SDave Hansen } 2649d57999e1SDave Hansen 2650d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2651d18e9008SMiklos Szeredi { 2652d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2653d18e9008SMiklos Szeredi if (error) 2654d18e9008SMiklos Szeredi return error; 2655d18e9008SMiklos Szeredi 2656d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2657d18e9008SMiklos Szeredi if (error) 2658d18e9008SMiklos Szeredi return error; 2659d18e9008SMiklos Szeredi 2660d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2661d18e9008SMiklos Szeredi } 2662d18e9008SMiklos Szeredi 26631acf0af9SDavid Howells /* 26641acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26651acf0af9SDavid Howells * dentry. 26661acf0af9SDavid Howells * 26671acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26681acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26691acf0af9SDavid Howells * 26701acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26711acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26721acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26731acf0af9SDavid Howells * 26741acf0af9SDavid Howells * Returns an error code otherwise. 26751acf0af9SDavid Howells */ 26762675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 267730d90494SAl Viro struct path *path, struct file *file, 2678015c3bbcSMiklos Szeredi const struct open_flags *op, 267964894cf8SAl Viro bool got_write, bool need_lookup, 268047237687SAl Viro int *opened) 2681d18e9008SMiklos Szeredi { 2682d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2683d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2684d18e9008SMiklos Szeredi umode_t mode; 2685d18e9008SMiklos Szeredi int error; 2686d18e9008SMiklos Szeredi int acc_mode; 2687d18e9008SMiklos Szeredi int create_error = 0; 2688d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2689116cc022SMiklos Szeredi bool excl; 2690d18e9008SMiklos Szeredi 2691d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2692d18e9008SMiklos Szeredi 2693d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2694d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 26952675a4ebSAl Viro error = -ENOENT; 2696d18e9008SMiklos Szeredi goto out; 2697d18e9008SMiklos Szeredi } 2698d18e9008SMiklos Szeredi 269962b259d8SMiklos Szeredi mode = op->mode; 2700d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2701d18e9008SMiklos Szeredi mode &= ~current_umask(); 2702d18e9008SMiklos Szeredi 2703116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2704116cc022SMiklos Szeredi if (excl) 2705d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2706d18e9008SMiklos Szeredi 2707d18e9008SMiklos Szeredi /* 2708d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2709d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2710d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2711d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2712d18e9008SMiklos Szeredi * 2713d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2714d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2715d18e9008SMiklos Szeredi */ 271664894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 271764894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 271864894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2719d18e9008SMiklos Szeredi /* 2720d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2721d18e9008SMiklos Szeredi * back to lookup + open 2722d18e9008SMiklos Szeredi */ 2723d18e9008SMiklos Szeredi goto no_open; 2724d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2725d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 272664894cf8SAl Viro create_error = -EROFS; 2727d18e9008SMiklos Szeredi goto no_open; 2728d18e9008SMiklos Szeredi } else { 2729d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 273064894cf8SAl Viro create_error = -EROFS; 2731d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2732d18e9008SMiklos Szeredi } 2733d18e9008SMiklos Szeredi } 2734d18e9008SMiklos Szeredi 2735d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 273638227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2737d18e9008SMiklos Szeredi if (error) { 2738d18e9008SMiklos Szeredi create_error = error; 2739d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2740d18e9008SMiklos Szeredi goto no_open; 2741d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2742d18e9008SMiklos Szeredi } 2743d18e9008SMiklos Szeredi } 2744d18e9008SMiklos Szeredi 2745d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2746d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2747d18e9008SMiklos Szeredi 274830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 274930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 275030d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 275147237687SAl Viro opened); 2752d9585277SAl Viro if (error < 0) { 2753d9585277SAl Viro if (create_error && error == -ENOENT) 2754d9585277SAl Viro error = create_error; 2755d18e9008SMiklos Szeredi goto out; 2756d18e9008SMiklos Szeredi } 2757d18e9008SMiklos Szeredi 2758d9585277SAl Viro if (error) { /* returned 1, that is */ 275930d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27602675a4ebSAl Viro error = -EIO; 2761d18e9008SMiklos Szeredi goto out; 2762d18e9008SMiklos Szeredi } 276330d90494SAl Viro if (file->f_path.dentry) { 2764d18e9008SMiklos Szeredi dput(dentry); 276530d90494SAl Viro dentry = file->f_path.dentry; 2766d18e9008SMiklos Szeredi } 276703da633aSAl Viro if (*opened & FILE_CREATED) 276803da633aSAl Viro fsnotify_create(dir, dentry); 276903da633aSAl Viro if (!dentry->d_inode) { 277003da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 277103da633aSAl Viro if (create_error) { 277262b2ce96SSage Weil error = create_error; 277362b2ce96SSage Weil goto out; 277462b2ce96SSage Weil } 277503da633aSAl Viro } else { 277603da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 277703da633aSAl Viro error = -EEXIST; 277803da633aSAl Viro goto out; 277903da633aSAl Viro } 278003da633aSAl Viro } 2781d18e9008SMiklos Szeredi goto looked_up; 2782d18e9008SMiklos Szeredi } 2783d18e9008SMiklos Szeredi 2784d18e9008SMiklos Szeredi /* 2785d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2786d18e9008SMiklos Szeredi * here. 2787d18e9008SMiklos Szeredi */ 278803da633aSAl Viro acc_mode = op->acc_mode; 278903da633aSAl Viro if (*opened & FILE_CREATED) { 279003da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 279103da633aSAl Viro fsnotify_create(dir, dentry); 279203da633aSAl Viro acc_mode = MAY_OPEN; 279303da633aSAl Viro } 27942675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 27952675a4ebSAl Viro if (error) 27962675a4ebSAl Viro fput(file); 2797d18e9008SMiklos Szeredi 2798d18e9008SMiklos Szeredi out: 2799d18e9008SMiklos Szeredi dput(dentry); 28002675a4ebSAl Viro return error; 2801d18e9008SMiklos Szeredi 2802d18e9008SMiklos Szeredi no_open: 2803d18e9008SMiklos Szeredi if (need_lookup) { 280472bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2805d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28062675a4ebSAl Viro return PTR_ERR(dentry); 2807d18e9008SMiklos Szeredi 2808d18e9008SMiklos Szeredi if (create_error) { 2809d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2810d18e9008SMiklos Szeredi 28112675a4ebSAl Viro error = create_error; 2812d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2813d18e9008SMiklos Szeredi if (!dentry->d_inode) 2814d18e9008SMiklos Szeredi goto out; 2815d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2816d18e9008SMiklos Szeredi goto out; 2817d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2818d18e9008SMiklos Szeredi S_ISREG(dentry->d_inode->i_mode)) { 2819d18e9008SMiklos Szeredi goto out; 2820d18e9008SMiklos Szeredi } 2821d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2822d18e9008SMiklos Szeredi } 2823d18e9008SMiklos Szeredi } 2824d18e9008SMiklos Szeredi looked_up: 2825d18e9008SMiklos Szeredi path->dentry = dentry; 2826d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28272675a4ebSAl Viro return 1; 2828d18e9008SMiklos Szeredi } 2829d18e9008SMiklos Szeredi 283031e6b01fSNick Piggin /* 28311acf0af9SDavid Howells * Look up and maybe create and open the last component. 2832d58ffd35SMiklos Szeredi * 2833d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2834d58ffd35SMiklos Szeredi * 28351acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28361acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28371acf0af9SDavid Howells * 28381acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28391acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28401acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28411acf0af9SDavid Howells * specified then a negative dentry may be returned. 28421acf0af9SDavid Howells * 28431acf0af9SDavid Howells * An error code is returned otherwise. 28441acf0af9SDavid Howells * 28451acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28461acf0af9SDavid Howells * cleared otherwise prior to returning. 2847d58ffd35SMiklos Szeredi */ 28482675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 284930d90494SAl Viro struct file *file, 2850d58ffd35SMiklos Szeredi const struct open_flags *op, 285164894cf8SAl Viro bool got_write, int *opened) 2852d58ffd35SMiklos Szeredi { 2853d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 285454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2855d58ffd35SMiklos Szeredi struct dentry *dentry; 2856d58ffd35SMiklos Szeredi int error; 285754ef4872SMiklos Szeredi bool need_lookup; 2858d58ffd35SMiklos Szeredi 285947237687SAl Viro *opened &= ~FILE_CREATED; 2860201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2861d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28622675a4ebSAl Viro return PTR_ERR(dentry); 2863d58ffd35SMiklos Szeredi 2864d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2865d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2866d18e9008SMiklos Szeredi goto out_no_open; 2867d18e9008SMiklos Szeredi 2868d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 286964894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 287047237687SAl Viro need_lookup, opened); 2871d18e9008SMiklos Szeredi } 2872d18e9008SMiklos Szeredi 287354ef4872SMiklos Szeredi if (need_lookup) { 287454ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 287554ef4872SMiklos Szeredi 287672bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 287754ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28782675a4ebSAl Viro return PTR_ERR(dentry); 287954ef4872SMiklos Szeredi } 288054ef4872SMiklos Szeredi 2881d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2882d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2883d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2884d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2885d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2886d58ffd35SMiklos Szeredi /* 2887d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2888d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2889d58ffd35SMiklos Szeredi * the time when the file is created and when 2890d58ffd35SMiklos Szeredi * a permanent write count is taken through 2891015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2892d58ffd35SMiklos Szeredi */ 289364894cf8SAl Viro if (!got_write) { 289464894cf8SAl Viro error = -EROFS; 2895d58ffd35SMiklos Szeredi goto out_dput; 289664894cf8SAl Viro } 289747237687SAl Viro *opened |= FILE_CREATED; 2898d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2899d58ffd35SMiklos Szeredi if (error) 2900d58ffd35SMiklos Szeredi goto out_dput; 2901312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2902312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2903d58ffd35SMiklos Szeredi if (error) 2904d58ffd35SMiklos Szeredi goto out_dput; 2905d58ffd35SMiklos Szeredi } 2906d18e9008SMiklos Szeredi out_no_open: 2907d58ffd35SMiklos Szeredi path->dentry = dentry; 2908d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29092675a4ebSAl Viro return 1; 2910d58ffd35SMiklos Szeredi 2911d58ffd35SMiklos Szeredi out_dput: 2912d58ffd35SMiklos Szeredi dput(dentry); 29132675a4ebSAl Viro return error; 2914d58ffd35SMiklos Szeredi } 2915d58ffd35SMiklos Szeredi 2916d58ffd35SMiklos Szeredi /* 2917fe2d35ffSAl Viro * Handle the last step of open() 291831e6b01fSNick Piggin */ 29192675a4ebSAl Viro static int do_last(struct nameidata *nd, struct path *path, 292030d90494SAl Viro struct file *file, const struct open_flags *op, 2921669abf4eSJeff Layton int *opened, struct filename *name) 2922fb1cc555SAl Viro { 2923a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2924ca344a89SAl Viro int open_flag = op->open_flag; 292577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 292664894cf8SAl Viro bool got_write = false; 2927bcda7652SAl Viro int acc_mode = op->acc_mode; 2928a1eb3315SMiklos Szeredi struct inode *inode; 292977d660a8SMiklos Szeredi bool symlink_ok = false; 293016b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 293116b1c1cdSMiklos Szeredi bool retried = false; 293216c2cd71SAl Viro int error; 2933fb1cc555SAl Viro 2934c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2935c3e380b0SAl Viro nd->flags |= op->intent; 2936c3e380b0SAl Viro 2937bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2938fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2939fe2d35ffSAl Viro if (error) 29402675a4ebSAl Viro return error; 2941e83db167SMiklos Szeredi goto finish_open; 29421f36f774SAl Viro } 2943a2c36b45SAl Viro 2944ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2945fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2946fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2947bcda7652SAl Viro if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) 294877d660a8SMiklos Szeredi symlink_ok = true; 2949fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2950e97cdc87SAl Viro error = lookup_fast(nd, path, &inode); 295171574865SMiklos Szeredi if (likely(!error)) 295271574865SMiklos Szeredi goto finish_lookup; 295371574865SMiklos Szeredi 2954ce57dfc1SAl Viro if (error < 0) 29552675a4ebSAl Viro goto out; 2956a1eb3315SMiklos Szeredi 295737d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2958b6183df7SMiklos Szeredi } else { 2959fe2d35ffSAl Viro /* create side of things */ 2960a3fbbde7SAl Viro /* 2961b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2962b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2963b6183df7SMiklos Szeredi * about to look up 2964a3fbbde7SAl Viro */ 29659f1fafeeSAl Viro error = complete_walk(nd); 29669f1fafeeSAl Viro if (error) 29672675a4ebSAl Viro return error; 2968fe2d35ffSAl Viro 296933e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 297016c2cd71SAl Viro error = -EISDIR; 29711f36f774SAl Viro /* trailing slashes? */ 297231e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29732675a4ebSAl Viro goto out; 2974b6183df7SMiklos Szeredi } 29751f36f774SAl Viro 297616b1c1cdSMiklos Szeredi retry_lookup: 297764894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 297864894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 297964894cf8SAl Viro if (!error) 298064894cf8SAl Viro got_write = true; 298164894cf8SAl Viro /* 298264894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 298364894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 298464894cf8SAl Viro * dropping this one anyway. 298564894cf8SAl Viro */ 298664894cf8SAl Viro } 2987a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 298864894cf8SAl Viro error = lookup_open(nd, path, file, op, got_write, opened); 2989fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 2990fb1cc555SAl Viro 29912675a4ebSAl Viro if (error <= 0) { 29922675a4ebSAl Viro if (error) 2993d58ffd35SMiklos Szeredi goto out; 29946c0d46c4SAl Viro 299547237687SAl Viro if ((*opened & FILE_CREATED) || 2996496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 299777d660a8SMiklos Szeredi will_truncate = false; 2998d18e9008SMiklos Szeredi 2999adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3000d18e9008SMiklos Szeredi goto opened; 3001d18e9008SMiklos Szeredi } 3002d18e9008SMiklos Szeredi 300347237687SAl Viro if (*opened & FILE_CREATED) { 30049b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3005ca344a89SAl Viro open_flag &= ~O_TRUNC; 300677d660a8SMiklos Szeredi will_truncate = false; 3007bcda7652SAl Viro acc_mode = MAY_OPEN; 3008d58ffd35SMiklos Szeredi path_to_nameidata(path, nd); 3009e83db167SMiklos Szeredi goto finish_open_created; 3010fb1cc555SAl Viro } 3011fb1cc555SAl Viro 3012fb1cc555SAl Viro /* 30133134f37eSJeff Layton * create/update audit record if it already exists. 3014fb1cc555SAl Viro */ 3015b18825a7SDavid Howells if (d_is_positive(path->dentry)) 3016adb5c247SJeff Layton audit_inode(name, path->dentry, 0); 3017fb1cc555SAl Viro 3018d18e9008SMiklos Szeredi /* 3019d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3020d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3021d18e9008SMiklos Szeredi * necessary...) 3022d18e9008SMiklos Szeredi */ 302364894cf8SAl Viro if (got_write) { 3024d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 302564894cf8SAl Viro got_write = false; 3026d18e9008SMiklos Szeredi } 3027d18e9008SMiklos Szeredi 3028fb1cc555SAl Viro error = -EEXIST; 3029f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3030fb1cc555SAl Viro goto exit_dput; 3031fb1cc555SAl Viro 30329875cf80SDavid Howells error = follow_managed(path, nd->flags); 30339875cf80SDavid Howells if (error < 0) 3034fb1cc555SAl Viro goto exit_dput; 3035fb1cc555SAl Viro 3036a3fbbde7SAl Viro if (error) 3037a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3038a3fbbde7SAl Viro 3039decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3040decf3400SMiklos Szeredi inode = path->dentry->d_inode; 30415f5daac1SMiklos Szeredi finish_lookup: 30425f5daac1SMiklos Szeredi /* we _can_ be in RCU mode here */ 3043fb1cc555SAl Viro error = -ENOENT; 304422213318SAl Viro if (!inode || d_is_negative(path->dentry)) { 304554c33e7fSMiklos Szeredi path_to_nameidata(path, nd); 30462675a4ebSAl Viro goto out; 304754c33e7fSMiklos Szeredi } 30489e67f361SAl Viro 3049b18825a7SDavid Howells if (should_follow_link(path->dentry, !symlink_ok)) { 3050d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3051d45ea867SMiklos Szeredi if (unlikely(unlazy_walk(nd, path->dentry))) { 3052d45ea867SMiklos Szeredi error = -ECHILD; 30532675a4ebSAl Viro goto out; 3054d45ea867SMiklos Szeredi } 3055d45ea867SMiklos Szeredi } 3056d45ea867SMiklos Szeredi BUG_ON(inode != path->dentry->d_inode); 30572675a4ebSAl Viro return 1; 3058d45ea867SMiklos Szeredi } 3059fb1cc555SAl Viro 306016b1c1cdSMiklos Szeredi if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { 3061fb1cc555SAl Viro path_to_nameidata(path, nd); 306216b1c1cdSMiklos Szeredi } else { 306316b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 306416b1c1cdSMiklos Szeredi save_parent.mnt = mntget(path->mnt); 306516b1c1cdSMiklos Szeredi nd->path.dentry = path->dentry; 306616b1c1cdSMiklos Szeredi 306716b1c1cdSMiklos Szeredi } 3068decf3400SMiklos Szeredi nd->inode = inode; 3069a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3070bc77daa7SAl Viro finish_open: 3071a3fbbde7SAl Viro error = complete_walk(nd); 307216b1c1cdSMiklos Szeredi if (error) { 307316b1c1cdSMiklos Szeredi path_put(&save_parent); 30742675a4ebSAl Viro return error; 307516b1c1cdSMiklos Szeredi } 3076bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3077fb1cc555SAl Viro error = -EISDIR; 307844b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 30792675a4ebSAl Viro goto out; 3080af2f5542SMiklos Szeredi error = -ENOTDIR; 308144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 30822675a4ebSAl Viro goto out; 30836c0d46c4SAl Viro if (!S_ISREG(nd->inode->i_mode)) 308477d660a8SMiklos Szeredi will_truncate = false; 30856c0d46c4SAl Viro 30860f9d1a10SAl Viro if (will_truncate) { 30870f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30880f9d1a10SAl Viro if (error) 30892675a4ebSAl Viro goto out; 309064894cf8SAl Viro got_write = true; 30910f9d1a10SAl Viro } 3092e83db167SMiklos Szeredi finish_open_created: 3093bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3094ca344a89SAl Viro if (error) 30952675a4ebSAl Viro goto out; 30964aa7c634SMiklos Szeredi 30974aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 30984aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 30994aa7c634SMiklos Szeredi if (!error) { 31004aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31014aa7c634SMiklos Szeredi } else { 310230d90494SAl Viro if (error == -EOPENSTALE) 3103f60dc3dbSMiklos Szeredi goto stale_open; 3104015c3bbcSMiklos Szeredi goto out; 3105f60dc3dbSMiklos Szeredi } 3106a8277b9bSMiklos Szeredi opened: 31072675a4ebSAl Viro error = open_check_o_direct(file); 3108015c3bbcSMiklos Szeredi if (error) 3109015c3bbcSMiklos Szeredi goto exit_fput; 31103034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3111aa4caadbSMiklos Szeredi if (error) 3112aa4caadbSMiklos Szeredi goto exit_fput; 3113aa4caadbSMiklos Szeredi 31140f9d1a10SAl Viro if (will_truncate) { 31152675a4ebSAl Viro error = handle_truncate(file); 3116aa4caadbSMiklos Szeredi if (error) 3117aa4caadbSMiklos Szeredi goto exit_fput; 31180f9d1a10SAl Viro } 3119ca344a89SAl Viro out: 312064894cf8SAl Viro if (got_write) 31210f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 312216b1c1cdSMiklos Szeredi path_put(&save_parent); 3123e276ae67SMiklos Szeredi terminate_walk(nd); 31242675a4ebSAl Viro return error; 3125fb1cc555SAl Viro 3126fb1cc555SAl Viro exit_dput: 3127fb1cc555SAl Viro path_put_conditional(path, nd); 3128ca344a89SAl Viro goto out; 3129015c3bbcSMiklos Szeredi exit_fput: 31302675a4ebSAl Viro fput(file); 31312675a4ebSAl Viro goto out; 3132015c3bbcSMiklos Szeredi 3133f60dc3dbSMiklos Szeredi stale_open: 3134f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3135f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3136f60dc3dbSMiklos Szeredi goto out; 3137f60dc3dbSMiklos Szeredi 3138f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3139f60dc3dbSMiklos Szeredi path_put(&nd->path); 3140f60dc3dbSMiklos Szeredi nd->path = save_parent; 3141f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3142f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3143f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 314464894cf8SAl Viro if (got_write) { 3145f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 314664894cf8SAl Viro got_write = false; 3147f60dc3dbSMiklos Szeredi } 3148f60dc3dbSMiklos Szeredi retried = true; 3149f60dc3dbSMiklos Szeredi goto retry_lookup; 3150fb1cc555SAl Viro } 3151fb1cc555SAl Viro 315260545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 315360545d0dSAl Viro struct nameidata *nd, int flags, 315460545d0dSAl Viro const struct open_flags *op, 315560545d0dSAl Viro struct file *file, int *opened) 315660545d0dSAl Viro { 315760545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 315860545d0dSAl Viro struct dentry *dentry, *child; 315960545d0dSAl Viro struct inode *dir; 316060545d0dSAl Viro int error = path_lookupat(dfd, pathname->name, 316160545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 316260545d0dSAl Viro if (unlikely(error)) 316360545d0dSAl Viro return error; 316460545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 316560545d0dSAl Viro if (unlikely(error)) 316660545d0dSAl Viro goto out; 316760545d0dSAl Viro /* we want directory to be writable */ 316860545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 316960545d0dSAl Viro if (error) 317060545d0dSAl Viro goto out2; 317160545d0dSAl Viro dentry = nd->path.dentry; 317260545d0dSAl Viro dir = dentry->d_inode; 317360545d0dSAl Viro if (!dir->i_op->tmpfile) { 317460545d0dSAl Viro error = -EOPNOTSUPP; 317560545d0dSAl Viro goto out2; 317660545d0dSAl Viro } 317760545d0dSAl Viro child = d_alloc(dentry, &name); 317860545d0dSAl Viro if (unlikely(!child)) { 317960545d0dSAl Viro error = -ENOMEM; 318060545d0dSAl Viro goto out2; 318160545d0dSAl Viro } 318260545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 318360545d0dSAl Viro nd->flags |= op->intent; 318460545d0dSAl Viro dput(nd->path.dentry); 318560545d0dSAl Viro nd->path.dentry = child; 318660545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 318760545d0dSAl Viro if (error) 318860545d0dSAl Viro goto out2; 318960545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 319069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 319169a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 319260545d0dSAl Viro if (error) 319360545d0dSAl Viro goto out2; 319460545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 319560545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 319660545d0dSAl Viro if (error) 319760545d0dSAl Viro goto out2; 319860545d0dSAl Viro error = open_check_o_direct(file); 3199f4e0c30cSAl Viro if (error) { 320060545d0dSAl Viro fput(file); 3201f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3202f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3203f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3204f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3205f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3206f4e0c30cSAl Viro } 320760545d0dSAl Viro out2: 320860545d0dSAl Viro mnt_drop_write(nd->path.mnt); 320960545d0dSAl Viro out: 321060545d0dSAl Viro path_put(&nd->path); 321160545d0dSAl Viro return error; 321260545d0dSAl Viro } 321360545d0dSAl Viro 3214669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 321573d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32161da177e4SLinus Torvalds { 321730d90494SAl Viro struct file *file; 32189850c056SAl Viro struct path path; 321947237687SAl Viro int opened = 0; 322013aab428SAl Viro int error; 322131e6b01fSNick Piggin 322230d90494SAl Viro file = get_empty_filp(); 32231afc99beSAl Viro if (IS_ERR(file)) 32241afc99beSAl Viro return file; 322531e6b01fSNick Piggin 322630d90494SAl Viro file->f_flags = op->open_flag; 322731e6b01fSNick Piggin 3228bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 322960545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 323060545d0dSAl Viro goto out; 323160545d0dSAl Viro } 323260545d0dSAl Viro 3233980f3ea2SAl Viro error = path_init(dfd, pathname->name, flags, nd); 323431e6b01fSNick Piggin if (unlikely(error)) 32352675a4ebSAl Viro goto out; 32361da177e4SLinus Torvalds 32372675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 32382675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 32397b9337aaSNick Piggin struct path link = path; 3240def4af30SAl Viro void *cookie; 3241574197e0SAl Viro if (!(nd->flags & LOOKUP_FOLLOW)) { 324273d049a4SAl Viro path_put_conditional(&path, nd); 324373d049a4SAl Viro path_put(&nd->path); 32442675a4ebSAl Viro error = -ELOOP; 324540b39136SAl Viro break; 324640b39136SAl Viro } 3247800179c9SKees Cook error = may_follow_link(&link, nd); 3248800179c9SKees Cook if (unlikely(error)) 3249800179c9SKees Cook break; 325073d049a4SAl Viro nd->flags |= LOOKUP_PARENT; 325173d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3252574197e0SAl Viro error = follow_link(&link, nd, &cookie); 3253c3e380b0SAl Viro if (unlikely(error)) 32542675a4ebSAl Viro break; 32552675a4ebSAl Viro error = do_last(nd, &path, file, op, &opened, pathname); 3256574197e0SAl Viro put_link(nd, &link, cookie); 3257806b681cSAl Viro } 325810fa8e62SAl Viro out: 3259893b7775SAl Viro path_cleanup(nd); 32602675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32612675a4ebSAl Viro BUG_ON(!error); 326230d90494SAl Viro put_filp(file); 3263015c3bbcSMiklos Szeredi } 32642675a4ebSAl Viro if (unlikely(error)) { 32652675a4ebSAl Viro if (error == -EOPENSTALE) { 32662675a4ebSAl Viro if (flags & LOOKUP_RCU) 32672675a4ebSAl Viro error = -ECHILD; 32682675a4ebSAl Viro else 32692675a4ebSAl Viro error = -ESTALE; 32702675a4ebSAl Viro } 32712675a4ebSAl Viro file = ERR_PTR(error); 32722675a4ebSAl Viro } 32732675a4ebSAl Viro return file; 3274de459215SKirill Korotaev } 32751da177e4SLinus Torvalds 3276669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3277f9652e10SAl Viro const struct open_flags *op) 327813aab428SAl Viro { 327973d049a4SAl Viro struct nameidata nd; 3280f9652e10SAl Viro int flags = op->lookup_flags; 328113aab428SAl Viro struct file *filp; 328213aab428SAl Viro 328373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 328413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 328573d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 328613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 328773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 328813aab428SAl Viro return filp; 328913aab428SAl Viro } 329013aab428SAl Viro 329173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3292f9652e10SAl Viro const char *name, const struct open_flags *op) 329373d049a4SAl Viro { 329473d049a4SAl Viro struct nameidata nd; 329573d049a4SAl Viro struct file *file; 329651689104SPaul Moore struct filename *filename; 3297f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 329873d049a4SAl Viro 329973d049a4SAl Viro nd.root.mnt = mnt; 330073d049a4SAl Viro nd.root.dentry = dentry; 330173d049a4SAl Viro 3302b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 330373d049a4SAl Viro return ERR_PTR(-ELOOP); 330473d049a4SAl Viro 330551689104SPaul Moore filename = getname_kernel(name); 330651689104SPaul Moore if (unlikely(IS_ERR(filename))) 330751689104SPaul Moore return ERR_CAST(filename); 330851689104SPaul Moore 330951689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 331073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 331151689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 331273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 331351689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 331451689104SPaul Moore putname(filename); 331573d049a4SAl Viro return file; 331673d049a4SAl Viro } 331773d049a4SAl Viro 3318fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33191ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33201da177e4SLinus Torvalds { 3321c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3322ed75e95dSAl Viro struct nameidata nd; 3323c30dabfeSJan Kara int err2; 33241ac12b4bSJeff Layton int error; 33251ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33261ac12b4bSJeff Layton 33271ac12b4bSJeff Layton /* 33281ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33291ac12b4bSJeff Layton * other flags passed in are ignored! 33301ac12b4bSJeff Layton */ 33311ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33321ac12b4bSJeff Layton 3333fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3334ed75e95dSAl Viro if (error) 3335ed75e95dSAl Viro return ERR_PTR(error); 33361da177e4SLinus Torvalds 3337c663e5d8SChristoph Hellwig /* 3338c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3339c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3340c663e5d8SChristoph Hellwig */ 3341ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3342ed75e95dSAl Viro goto out; 3343ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3344ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3345c663e5d8SChristoph Hellwig 3346c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3347c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3348c663e5d8SChristoph Hellwig /* 3349c663e5d8SChristoph Hellwig * Do the final lookup. 3350c663e5d8SChristoph Hellwig */ 3351ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3352ed75e95dSAl Viro dentry = lookup_hash(&nd); 33531da177e4SLinus Torvalds if (IS_ERR(dentry)) 3354a8104a9fSAl Viro goto unlock; 3355c663e5d8SChristoph Hellwig 3356a8104a9fSAl Viro error = -EEXIST; 3357b18825a7SDavid Howells if (d_is_positive(dentry)) 3358a8104a9fSAl Viro goto fail; 3359b18825a7SDavid Howells 3360c663e5d8SChristoph Hellwig /* 3361c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3362c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3363c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3364c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3365c663e5d8SChristoph Hellwig */ 3366ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3367a8104a9fSAl Viro error = -ENOENT; 3368ed75e95dSAl Viro goto fail; 3369e9baf6e5SAl Viro } 3370c30dabfeSJan Kara if (unlikely(err2)) { 3371c30dabfeSJan Kara error = err2; 3372a8104a9fSAl Viro goto fail; 3373c30dabfeSJan Kara } 3374ed75e95dSAl Viro *path = nd.path; 3375e9baf6e5SAl Viro return dentry; 33761da177e4SLinus Torvalds fail: 3377a8104a9fSAl Viro dput(dentry); 3378a8104a9fSAl Viro dentry = ERR_PTR(error); 3379a8104a9fSAl Viro unlock: 3380dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3381c30dabfeSJan Kara if (!err2) 3382c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3383ed75e95dSAl Viro out: 3384dae6ad8fSAl Viro path_put(&nd.path); 3385ed75e95dSAl Viro return dentry; 3386dae6ad8fSAl Viro } 3387fa14a0b8SAl Viro 3388fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3389fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3390fa14a0b8SAl Viro { 339151689104SPaul Moore struct filename *filename = getname_kernel(pathname); 339251689104SPaul Moore struct dentry *res; 339351689104SPaul Moore 339451689104SPaul Moore if (IS_ERR(filename)) 339551689104SPaul Moore return ERR_CAST(filename); 339651689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 339751689104SPaul Moore putname(filename); 339851689104SPaul Moore return res; 3399fa14a0b8SAl Viro } 3400dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3401dae6ad8fSAl Viro 3402921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3403921a1650SAl Viro { 3404921a1650SAl Viro dput(dentry); 3405921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3406a8104a9fSAl Viro mnt_drop_write(path->mnt); 3407921a1650SAl Viro path_put(path); 3408921a1650SAl Viro } 3409921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3410921a1650SAl Viro 34111ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34121ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3413dae6ad8fSAl Viro { 341491a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3415dae6ad8fSAl Viro struct dentry *res; 3416dae6ad8fSAl Viro if (IS_ERR(tmp)) 3417dae6ad8fSAl Viro return ERR_CAST(tmp); 3418fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3419dae6ad8fSAl Viro putname(tmp); 3420dae6ad8fSAl Viro return res; 3421dae6ad8fSAl Viro } 3422dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3423dae6ad8fSAl Viro 34241a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34251da177e4SLinus Torvalds { 3426a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34271da177e4SLinus Torvalds 34281da177e4SLinus Torvalds if (error) 34291da177e4SLinus Torvalds return error; 34301da177e4SLinus Torvalds 3431975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34321da177e4SLinus Torvalds return -EPERM; 34331da177e4SLinus Torvalds 3434acfa4380SAl Viro if (!dir->i_op->mknod) 34351da177e4SLinus Torvalds return -EPERM; 34361da177e4SLinus Torvalds 343708ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 343808ce5f16SSerge E. Hallyn if (error) 343908ce5f16SSerge E. Hallyn return error; 344008ce5f16SSerge E. Hallyn 34411da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34421da177e4SLinus Torvalds if (error) 34431da177e4SLinus Torvalds return error; 34441da177e4SLinus Torvalds 34451da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3446a74574aaSStephen Smalley if (!error) 3447f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34481da177e4SLinus Torvalds return error; 34491da177e4SLinus Torvalds } 34504d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34511da177e4SLinus Torvalds 3452f69aac00SAl Viro static int may_mknod(umode_t mode) 3453463c3197SDave Hansen { 3454463c3197SDave Hansen switch (mode & S_IFMT) { 3455463c3197SDave Hansen case S_IFREG: 3456463c3197SDave Hansen case S_IFCHR: 3457463c3197SDave Hansen case S_IFBLK: 3458463c3197SDave Hansen case S_IFIFO: 3459463c3197SDave Hansen case S_IFSOCK: 3460463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3461463c3197SDave Hansen return 0; 3462463c3197SDave Hansen case S_IFDIR: 3463463c3197SDave Hansen return -EPERM; 3464463c3197SDave Hansen default: 3465463c3197SDave Hansen return -EINVAL; 3466463c3197SDave Hansen } 3467463c3197SDave Hansen } 3468463c3197SDave Hansen 34698208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34702e4d0924SHeiko Carstens unsigned, dev) 34711da177e4SLinus Torvalds { 34721da177e4SLinus Torvalds struct dentry *dentry; 3473dae6ad8fSAl Viro struct path path; 3474dae6ad8fSAl Viro int error; 3475972567f1SJeff Layton unsigned int lookup_flags = 0; 34761da177e4SLinus Torvalds 34778e4bfca1SAl Viro error = may_mknod(mode); 34788e4bfca1SAl Viro if (error) 34798e4bfca1SAl Viro return error; 3480972567f1SJeff Layton retry: 3481972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3482dae6ad8fSAl Viro if (IS_ERR(dentry)) 3483dae6ad8fSAl Viro return PTR_ERR(dentry); 34842ad94ae6SAl Viro 3485dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3486ce3b0f8dSAl Viro mode &= ~current_umask(); 3487dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3488be6d3e56SKentaro Takeda if (error) 3489a8104a9fSAl Viro goto out; 34901da177e4SLinus Torvalds switch (mode & S_IFMT) { 34911da177e4SLinus Torvalds case 0: case S_IFREG: 3492312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34931da177e4SLinus Torvalds break; 34941da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3495dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34961da177e4SLinus Torvalds new_decode_dev(dev)); 34971da177e4SLinus Torvalds break; 34981da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3499dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35001da177e4SLinus Torvalds break; 35011da177e4SLinus Torvalds } 3502a8104a9fSAl Viro out: 3503921a1650SAl Viro done_path_create(&path, dentry); 3504972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3505972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3506972567f1SJeff Layton goto retry; 3507972567f1SJeff Layton } 35081da177e4SLinus Torvalds return error; 35091da177e4SLinus Torvalds } 35101da177e4SLinus Torvalds 35118208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35125590ff0dSUlrich Drepper { 35135590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35145590ff0dSUlrich Drepper } 35155590ff0dSUlrich Drepper 351618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35171da177e4SLinus Torvalds { 3518a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35198de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35201da177e4SLinus Torvalds 35211da177e4SLinus Torvalds if (error) 35221da177e4SLinus Torvalds return error; 35231da177e4SLinus Torvalds 3524acfa4380SAl Viro if (!dir->i_op->mkdir) 35251da177e4SLinus Torvalds return -EPERM; 35261da177e4SLinus Torvalds 35271da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35281da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35291da177e4SLinus Torvalds if (error) 35301da177e4SLinus Torvalds return error; 35311da177e4SLinus Torvalds 35328de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35338de52778SAl Viro return -EMLINK; 35348de52778SAl Viro 35351da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3536a74574aaSStephen Smalley if (!error) 3537f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35381da177e4SLinus Torvalds return error; 35391da177e4SLinus Torvalds } 35404d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35411da177e4SLinus Torvalds 3542a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35431da177e4SLinus Torvalds { 35446902d925SDave Hansen struct dentry *dentry; 3545dae6ad8fSAl Viro struct path path; 3546dae6ad8fSAl Viro int error; 3547b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35481da177e4SLinus Torvalds 3549b76d8b82SJeff Layton retry: 3550b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35516902d925SDave Hansen if (IS_ERR(dentry)) 3552dae6ad8fSAl Viro return PTR_ERR(dentry); 35536902d925SDave Hansen 3554dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3555ce3b0f8dSAl Viro mode &= ~current_umask(); 3556dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3557a8104a9fSAl Viro if (!error) 3558dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3559921a1650SAl Viro done_path_create(&path, dentry); 3560b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3561b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3562b76d8b82SJeff Layton goto retry; 3563b76d8b82SJeff Layton } 35641da177e4SLinus Torvalds return error; 35651da177e4SLinus Torvalds } 35661da177e4SLinus Torvalds 3567a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35685590ff0dSUlrich Drepper { 35695590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35705590ff0dSUlrich Drepper } 35715590ff0dSUlrich Drepper 35721da177e4SLinus Torvalds /* 3573a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3574c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3575a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3576a71905f0SSage Weil * then we drop the dentry now. 35771da177e4SLinus Torvalds * 35781da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35791da177e4SLinus Torvalds * do a 35801da177e4SLinus Torvalds * 35811da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35821da177e4SLinus Torvalds * return -EBUSY; 35831da177e4SLinus Torvalds * 35841da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35851da177e4SLinus Torvalds * that is still in use by something else.. 35861da177e4SLinus Torvalds */ 35871da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35881da177e4SLinus Torvalds { 35891da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35901da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 359198474236SWaiman Long if (dentry->d_lockref.count == 1) 35921da177e4SLinus Torvalds __d_drop(dentry); 35931da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35941da177e4SLinus Torvalds } 35954d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 35961da177e4SLinus Torvalds 35971da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35981da177e4SLinus Torvalds { 35991da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36001da177e4SLinus Torvalds 36011da177e4SLinus Torvalds if (error) 36021da177e4SLinus Torvalds return error; 36031da177e4SLinus Torvalds 3604acfa4380SAl Viro if (!dir->i_op->rmdir) 36051da177e4SLinus Torvalds return -EPERM; 36061da177e4SLinus Torvalds 36071d2ef590SAl Viro dget(dentry); 36081b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3609912dbc15SSage Weil 36101da177e4SLinus Torvalds error = -EBUSY; 36117af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3612912dbc15SSage Weil goto out; 3613912dbc15SSage Weil 36141da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3615912dbc15SSage Weil if (error) 3616912dbc15SSage Weil goto out; 3617912dbc15SSage Weil 36183cebde24SSage Weil shrink_dcache_parent(dentry); 36191da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3620912dbc15SSage Weil if (error) 3621912dbc15SSage Weil goto out; 3622912dbc15SSage Weil 36231da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3624d83c49f3SAl Viro dont_mount(dentry); 36258ed936b5SEric W. Biederman detach_mounts(dentry); 36261da177e4SLinus Torvalds 3627912dbc15SSage Weil out: 3628912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36291d2ef590SAl Viro dput(dentry); 3630912dbc15SSage Weil if (!error) 3631912dbc15SSage Weil d_delete(dentry); 36321da177e4SLinus Torvalds return error; 36331da177e4SLinus Torvalds } 36344d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36351da177e4SLinus Torvalds 36365590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36371da177e4SLinus Torvalds { 36381da177e4SLinus Torvalds int error = 0; 363991a27b2aSJeff Layton struct filename *name; 36401da177e4SLinus Torvalds struct dentry *dentry; 36411da177e4SLinus Torvalds struct nameidata nd; 3642c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3643c6ee9206SJeff Layton retry: 3644c6ee9206SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 364591a27b2aSJeff Layton if (IS_ERR(name)) 364691a27b2aSJeff Layton return PTR_ERR(name); 36471da177e4SLinus Torvalds 36481da177e4SLinus Torvalds switch(nd.last_type) { 36491da177e4SLinus Torvalds case LAST_DOTDOT: 36501da177e4SLinus Torvalds error = -ENOTEMPTY; 36511da177e4SLinus Torvalds goto exit1; 36521da177e4SLinus Torvalds case LAST_DOT: 36531da177e4SLinus Torvalds error = -EINVAL; 36541da177e4SLinus Torvalds goto exit1; 36551da177e4SLinus Torvalds case LAST_ROOT: 36561da177e4SLinus Torvalds error = -EBUSY; 36571da177e4SLinus Torvalds goto exit1; 36581da177e4SLinus Torvalds } 36590612d9fbSOGAWA Hirofumi 36600612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3661c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3662c30dabfeSJan Kara if (error) 3663c30dabfeSJan Kara goto exit1; 36640612d9fbSOGAWA Hirofumi 36654ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 366649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 36671da177e4SLinus Torvalds error = PTR_ERR(dentry); 36686902d925SDave Hansen if (IS_ERR(dentry)) 36696902d925SDave Hansen goto exit2; 3670e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3671e6bc45d6STheodore Ts'o error = -ENOENT; 3672e6bc45d6STheodore Ts'o goto exit3; 3673e6bc45d6STheodore Ts'o } 3674be6d3e56SKentaro Takeda error = security_path_rmdir(&nd.path, dentry); 3675be6d3e56SKentaro Takeda if (error) 3676c30dabfeSJan Kara goto exit3; 36774ac91378SJan Blunck error = vfs_rmdir(nd.path.dentry->d_inode, dentry); 36780622753bSDave Hansen exit3: 36791da177e4SLinus Torvalds dput(dentry); 36806902d925SDave Hansen exit2: 36814ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3682c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 36831da177e4SLinus Torvalds exit1: 36841d957f9bSJan Blunck path_put(&nd.path); 36851da177e4SLinus Torvalds putname(name); 3686c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3687c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3688c6ee9206SJeff Layton goto retry; 3689c6ee9206SJeff Layton } 36901da177e4SLinus Torvalds return error; 36911da177e4SLinus Torvalds } 36921da177e4SLinus Torvalds 36933cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36945590ff0dSUlrich Drepper { 36955590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36965590ff0dSUlrich Drepper } 36975590ff0dSUlrich Drepper 3698b21996e3SJ. Bruce Fields /** 3699b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3700b21996e3SJ. Bruce Fields * @dir: parent directory 3701b21996e3SJ. Bruce Fields * @dentry: victim 3702b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3703b21996e3SJ. Bruce Fields * 3704b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3705b21996e3SJ. Bruce Fields * 3706b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3707b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3708b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3709b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3710b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3711b21996e3SJ. Bruce Fields * 3712b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3713b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3714b21996e3SJ. Bruce Fields * to be NFS exported. 3715b21996e3SJ. Bruce Fields */ 3716b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37171da177e4SLinus Torvalds { 37189accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37191da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37201da177e4SLinus Torvalds 37211da177e4SLinus Torvalds if (error) 37221da177e4SLinus Torvalds return error; 37231da177e4SLinus Torvalds 3724acfa4380SAl Viro if (!dir->i_op->unlink) 37251da177e4SLinus Torvalds return -EPERM; 37261da177e4SLinus Torvalds 37279accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37288ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37291da177e4SLinus Torvalds error = -EBUSY; 37301da177e4SLinus Torvalds else { 37311da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3732bec1052eSAl Viro if (!error) { 37335a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37345a14696cSJ. Bruce Fields if (error) 3735b21996e3SJ. Bruce Fields goto out; 37361da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37378ed936b5SEric W. Biederman if (!error) { 3738d83c49f3SAl Viro dont_mount(dentry); 37398ed936b5SEric W. Biederman detach_mounts(dentry); 37408ed936b5SEric W. Biederman } 3741bec1052eSAl Viro } 37421da177e4SLinus Torvalds } 3743b21996e3SJ. Bruce Fields out: 37449accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37451da177e4SLinus Torvalds 37461da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37471da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37489accbb97SJ. Bruce Fields fsnotify_link_count(target); 37491da177e4SLinus Torvalds d_delete(dentry); 37501da177e4SLinus Torvalds } 37510eeca283SRobert Love 37521da177e4SLinus Torvalds return error; 37531da177e4SLinus Torvalds } 37544d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37551da177e4SLinus Torvalds 37561da177e4SLinus Torvalds /* 37571da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37581b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37591da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37601da177e4SLinus Torvalds * while waiting on the I/O. 37611da177e4SLinus Torvalds */ 37625590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37631da177e4SLinus Torvalds { 37642ad94ae6SAl Viro int error; 376591a27b2aSJeff Layton struct filename *name; 37661da177e4SLinus Torvalds struct dentry *dentry; 37671da177e4SLinus Torvalds struct nameidata nd; 37681da177e4SLinus Torvalds struct inode *inode = NULL; 3769b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37705d18f813SJeff Layton unsigned int lookup_flags = 0; 37715d18f813SJeff Layton retry: 37725d18f813SJeff Layton name = user_path_parent(dfd, pathname, &nd, lookup_flags); 377391a27b2aSJeff Layton if (IS_ERR(name)) 377491a27b2aSJeff Layton return PTR_ERR(name); 37752ad94ae6SAl Viro 37761da177e4SLinus Torvalds error = -EISDIR; 37771da177e4SLinus Torvalds if (nd.last_type != LAST_NORM) 37781da177e4SLinus Torvalds goto exit1; 37790612d9fbSOGAWA Hirofumi 37800612d9fbSOGAWA Hirofumi nd.flags &= ~LOOKUP_PARENT; 3781c30dabfeSJan Kara error = mnt_want_write(nd.path.mnt); 3782c30dabfeSJan Kara if (error) 3783c30dabfeSJan Kara goto exit1; 3784b21996e3SJ. Bruce Fields retry_deleg: 37854ac91378SJan Blunck mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 378649705b77SChristoph Hellwig dentry = lookup_hash(&nd); 37871da177e4SLinus Torvalds error = PTR_ERR(dentry); 37881da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37891da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 379050338b88STörök Edwin if (nd.last.name[nd.last.len]) 379150338b88STörök Edwin goto slashes; 37921da177e4SLinus Torvalds inode = dentry->d_inode; 3793b18825a7SDavid Howells if (d_is_negative(dentry)) 3794e6bc45d6STheodore Ts'o goto slashes; 37957de9c6eeSAl Viro ihold(inode); 3796be6d3e56SKentaro Takeda error = security_path_unlink(&nd.path, dentry); 3797be6d3e56SKentaro Takeda if (error) 3798c30dabfeSJan Kara goto exit2; 3799b21996e3SJ. Bruce Fields error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); 38001da177e4SLinus Torvalds exit2: 38011da177e4SLinus Torvalds dput(dentry); 38021da177e4SLinus Torvalds } 38034ac91378SJan Blunck mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 38041da177e4SLinus Torvalds if (inode) 38051da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3806b21996e3SJ. Bruce Fields inode = NULL; 3807b21996e3SJ. Bruce Fields if (delegated_inode) { 38085a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3809b21996e3SJ. Bruce Fields if (!error) 3810b21996e3SJ. Bruce Fields goto retry_deleg; 3811b21996e3SJ. Bruce Fields } 3812c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 38131da177e4SLinus Torvalds exit1: 38141d957f9bSJan Blunck path_put(&nd.path); 38151da177e4SLinus Torvalds putname(name); 38165d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38175d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38185d18f813SJeff Layton inode = NULL; 38195d18f813SJeff Layton goto retry; 38205d18f813SJeff Layton } 38211da177e4SLinus Torvalds return error; 38221da177e4SLinus Torvalds 38231da177e4SLinus Torvalds slashes: 3824b18825a7SDavid Howells if (d_is_negative(dentry)) 3825b18825a7SDavid Howells error = -ENOENT; 382644b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3827b18825a7SDavid Howells error = -EISDIR; 3828b18825a7SDavid Howells else 3829b18825a7SDavid Howells error = -ENOTDIR; 38301da177e4SLinus Torvalds goto exit2; 38311da177e4SLinus Torvalds } 38321da177e4SLinus Torvalds 38332e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38345590ff0dSUlrich Drepper { 38355590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38365590ff0dSUlrich Drepper return -EINVAL; 38375590ff0dSUlrich Drepper 38385590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38395590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38405590ff0dSUlrich Drepper 38415590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38425590ff0dSUlrich Drepper } 38435590ff0dSUlrich Drepper 38443480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38455590ff0dSUlrich Drepper { 38465590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38475590ff0dSUlrich Drepper } 38485590ff0dSUlrich Drepper 3849db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38501da177e4SLinus Torvalds { 3851a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38521da177e4SLinus Torvalds 38531da177e4SLinus Torvalds if (error) 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds 3856acfa4380SAl Viro if (!dir->i_op->symlink) 38571da177e4SLinus Torvalds return -EPERM; 38581da177e4SLinus Torvalds 38591da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38601da177e4SLinus Torvalds if (error) 38611da177e4SLinus Torvalds return error; 38621da177e4SLinus Torvalds 38631da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3864a74574aaSStephen Smalley if (!error) 3865f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38661da177e4SLinus Torvalds return error; 38671da177e4SLinus Torvalds } 38684d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38691da177e4SLinus Torvalds 38702e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38712e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38721da177e4SLinus Torvalds { 38732ad94ae6SAl Viro int error; 387491a27b2aSJeff Layton struct filename *from; 38756902d925SDave Hansen struct dentry *dentry; 3876dae6ad8fSAl Viro struct path path; 3877f46d3567SJeff Layton unsigned int lookup_flags = 0; 38781da177e4SLinus Torvalds 38791da177e4SLinus Torvalds from = getname(oldname); 38801da177e4SLinus Torvalds if (IS_ERR(from)) 38811da177e4SLinus Torvalds return PTR_ERR(from); 3882f46d3567SJeff Layton retry: 3883f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 38841da177e4SLinus Torvalds error = PTR_ERR(dentry); 38856902d925SDave Hansen if (IS_ERR(dentry)) 3886dae6ad8fSAl Viro goto out_putname; 38876902d925SDave Hansen 388891a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3889a8104a9fSAl Viro if (!error) 389091a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3891921a1650SAl Viro done_path_create(&path, dentry); 3892f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3893f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3894f46d3567SJeff Layton goto retry; 3895f46d3567SJeff Layton } 38966902d925SDave Hansen out_putname: 38971da177e4SLinus Torvalds putname(from); 38981da177e4SLinus Torvalds return error; 38991da177e4SLinus Torvalds } 39001da177e4SLinus Torvalds 39013480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39025590ff0dSUlrich Drepper { 39035590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39045590ff0dSUlrich Drepper } 39055590ff0dSUlrich Drepper 3906146a8595SJ. Bruce Fields /** 3907146a8595SJ. Bruce Fields * vfs_link - create a new link 3908146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3909146a8595SJ. Bruce Fields * @dir: new parent 3910146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3911146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3912146a8595SJ. Bruce Fields * 3913146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3914146a8595SJ. Bruce Fields * 3915146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3916146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3917146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3918146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3919146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3920146a8595SJ. Bruce Fields * 3921146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3922146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3923146a8595SJ. Bruce Fields * to be NFS exported. 3924146a8595SJ. Bruce Fields */ 3925146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39261da177e4SLinus Torvalds { 39271da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39288de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39291da177e4SLinus Torvalds int error; 39301da177e4SLinus Torvalds 39311da177e4SLinus Torvalds if (!inode) 39321da177e4SLinus Torvalds return -ENOENT; 39331da177e4SLinus Torvalds 3934a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39351da177e4SLinus Torvalds if (error) 39361da177e4SLinus Torvalds return error; 39371da177e4SLinus Torvalds 39381da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39391da177e4SLinus Torvalds return -EXDEV; 39401da177e4SLinus Torvalds 39411da177e4SLinus Torvalds /* 39421da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39431da177e4SLinus Torvalds */ 39441da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39451da177e4SLinus Torvalds return -EPERM; 3946acfa4380SAl Viro if (!dir->i_op->link) 39471da177e4SLinus Torvalds return -EPERM; 39487e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39491da177e4SLinus Torvalds return -EPERM; 39501da177e4SLinus Torvalds 39511da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39521da177e4SLinus Torvalds if (error) 39531da177e4SLinus Torvalds return error; 39541da177e4SLinus Torvalds 39557e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3956aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3957f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3958aae8a97dSAneesh Kumar K.V error = -ENOENT; 39598de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39608de52778SAl Viro error = -EMLINK; 3961146a8595SJ. Bruce Fields else { 3962146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3963146a8595SJ. Bruce Fields if (!error) 39641da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3965146a8595SJ. Bruce Fields } 3966f4e0c30cSAl Viro 3967f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3968f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3969f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3970f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3971f4e0c30cSAl Viro } 39727e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3973e31e14ecSStephen Smalley if (!error) 39747e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39751da177e4SLinus Torvalds return error; 39761da177e4SLinus Torvalds } 39774d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39781da177e4SLinus Torvalds 39791da177e4SLinus Torvalds /* 39801da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39811da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 39821da177e4SLinus Torvalds * newname. --KAB 39831da177e4SLinus Torvalds * 39841da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 39851da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 39861da177e4SLinus Torvalds * and other special files. --ADM 39871da177e4SLinus Torvalds */ 39882e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 39892e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 39901da177e4SLinus Torvalds { 39911da177e4SLinus Torvalds struct dentry *new_dentry; 3992dae6ad8fSAl Viro struct path old_path, new_path; 3993146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 399411a7b371SAneesh Kumar K.V int how = 0; 39951da177e4SLinus Torvalds int error; 39961da177e4SLinus Torvalds 399711a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 3998c04030e1SUlrich Drepper return -EINVAL; 399911a7b371SAneesh Kumar K.V /* 4000f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4001f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4002f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 400311a7b371SAneesh Kumar K.V */ 4004f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4005f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4006f0cc6ffbSLinus Torvalds return -ENOENT; 400711a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4008f0cc6ffbSLinus Torvalds } 4009c04030e1SUlrich Drepper 401011a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 401111a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4012442e31caSJeff Layton retry: 401311a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40141da177e4SLinus Torvalds if (error) 40152ad94ae6SAl Viro return error; 40162ad94ae6SAl Viro 4017442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4018442e31caSJeff Layton (how & LOOKUP_REVAL)); 40191da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40206902d925SDave Hansen if (IS_ERR(new_dentry)) 4021dae6ad8fSAl Viro goto out; 4022dae6ad8fSAl Viro 4023dae6ad8fSAl Viro error = -EXDEV; 4024dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4025dae6ad8fSAl Viro goto out_dput; 4026800179c9SKees Cook error = may_linkat(&old_path); 4027800179c9SKees Cook if (unlikely(error)) 4028800179c9SKees Cook goto out_dput; 4029dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4030be6d3e56SKentaro Takeda if (error) 4031a8104a9fSAl Viro goto out_dput; 4032146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 403375c3f29dSDave Hansen out_dput: 4034921a1650SAl Viro done_path_create(&new_path, new_dentry); 4035146a8595SJ. Bruce Fields if (delegated_inode) { 4036146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4037d22e6338SOleg Drokin if (!error) { 4038d22e6338SOleg Drokin path_put(&old_path); 4039146a8595SJ. Bruce Fields goto retry; 4040146a8595SJ. Bruce Fields } 4041d22e6338SOleg Drokin } 4042442e31caSJeff Layton if (retry_estale(error, how)) { 4043d22e6338SOleg Drokin path_put(&old_path); 4044442e31caSJeff Layton how |= LOOKUP_REVAL; 4045442e31caSJeff Layton goto retry; 4046442e31caSJeff Layton } 40471da177e4SLinus Torvalds out: 40482d8f3038SAl Viro path_put(&old_path); 40491da177e4SLinus Torvalds 40501da177e4SLinus Torvalds return error; 40511da177e4SLinus Torvalds } 40521da177e4SLinus Torvalds 40533480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40545590ff0dSUlrich Drepper { 4055c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40565590ff0dSUlrich Drepper } 40575590ff0dSUlrich Drepper 4058bc27027aSMiklos Szeredi /** 4059bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4060bc27027aSMiklos Szeredi * @old_dir: parent of source 4061bc27027aSMiklos Szeredi * @old_dentry: source 4062bc27027aSMiklos Szeredi * @new_dir: parent of destination 4063bc27027aSMiklos Szeredi * @new_dentry: destination 4064bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4065520c8b16SMiklos Szeredi * @flags: rename flags 4066bc27027aSMiklos Szeredi * 4067bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4068bc27027aSMiklos Szeredi * 4069bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4070bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4071bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4072bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4073bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4074bc27027aSMiklos Szeredi * so. 4075bc27027aSMiklos Szeredi * 4076bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4077bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4078bc27027aSMiklos Szeredi * to be NFS exported. 4079bc27027aSMiklos Szeredi * 40801da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40811da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 40821da177e4SLinus Torvalds * Problems: 4083d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 40841da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 40851da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4086a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 40871da177e4SLinus Torvalds * story. 40886cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 40896cedba89SJ. Bruce Fields * and source (if it is not a directory). 40901b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 40911da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 40921da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4093a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 40941da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 40951da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 40961da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4097a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 40981da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 40991da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41001da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4101e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41021b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41031da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4104c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41051da177e4SLinus Torvalds * locking]. 41061da177e4SLinus Torvalds */ 41071da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41088e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4109520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41101da177e4SLinus Torvalds { 41111da177e4SLinus Torvalds int error; 4112bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 411359b0df21SEric Paris const unsigned char *old_name; 4114bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4115bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4116da1ce067SMiklos Szeredi bool new_is_dir = false; 4117da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41181da177e4SLinus Torvalds 4119bc27027aSMiklos Szeredi if (source == target) 41201da177e4SLinus Torvalds return 0; 41211da177e4SLinus Torvalds 41221da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41231da177e4SLinus Torvalds if (error) 41241da177e4SLinus Torvalds return error; 41251da177e4SLinus Torvalds 4126da1ce067SMiklos Szeredi if (!target) { 4127a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4128da1ce067SMiklos Szeredi } else { 4129da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4130da1ce067SMiklos Szeredi 4131da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41321da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4133da1ce067SMiklos Szeredi else 4134da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4135da1ce067SMiklos Szeredi } 41361da177e4SLinus Torvalds if (error) 41371da177e4SLinus Torvalds return error; 41381da177e4SLinus Torvalds 41397177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41401da177e4SLinus Torvalds return -EPERM; 41411da177e4SLinus Torvalds 4142520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4143520c8b16SMiklos Szeredi return -EINVAL; 4144520c8b16SMiklos Szeredi 4145bc27027aSMiklos Szeredi /* 4146bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4147bc27027aSMiklos Szeredi * we'll need to flip '..'. 4148bc27027aSMiklos Szeredi */ 4149da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4150da1ce067SMiklos Szeredi if (is_dir) { 4151bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4152bc27027aSMiklos Szeredi if (error) 4153bc27027aSMiklos Szeredi return error; 4154bc27027aSMiklos Szeredi } 4155da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4156da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4157da1ce067SMiklos Szeredi if (error) 4158da1ce067SMiklos Szeredi return error; 4159da1ce067SMiklos Szeredi } 4160da1ce067SMiklos Szeredi } 41610eeca283SRobert Love 41620b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41630b3974ebSMiklos Szeredi flags); 4164bc27027aSMiklos Szeredi if (error) 4165bc27027aSMiklos Szeredi return error; 4166bc27027aSMiklos Szeredi 4167bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4168bc27027aSMiklos Szeredi dget(new_dentry); 4169da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4170bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4171bc27027aSMiklos Szeredi else if (target) 4172bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4173bc27027aSMiklos Szeredi 4174bc27027aSMiklos Szeredi error = -EBUSY; 41757af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4176bc27027aSMiklos Szeredi goto out; 4177bc27027aSMiklos Szeredi 4178da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4179bc27027aSMiklos Szeredi error = -EMLINK; 4180da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4181bc27027aSMiklos Szeredi goto out; 4182da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4183da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4184da1ce067SMiklos Szeredi goto out; 4185da1ce067SMiklos Szeredi } 4186da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4187bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4188da1ce067SMiklos Szeredi if (!is_dir) { 4189bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4190bc27027aSMiklos Szeredi if (error) 4191bc27027aSMiklos Szeredi goto out; 4192da1ce067SMiklos Szeredi } 4193da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4194bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4195bc27027aSMiklos Szeredi if (error) 4196bc27027aSMiklos Szeredi goto out; 4197bc27027aSMiklos Szeredi } 41987177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4199520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4200520c8b16SMiklos Szeredi new_dir, new_dentry); 4201520c8b16SMiklos Szeredi } else { 42027177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4203520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4204520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4205520c8b16SMiklos Szeredi } 4206bc27027aSMiklos Szeredi if (error) 4207bc27027aSMiklos Szeredi goto out; 4208bc27027aSMiklos Szeredi 4209da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42101da177e4SLinus Torvalds if (is_dir) 4211bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4212bc27027aSMiklos Szeredi dont_mount(new_dentry); 42138ed936b5SEric W. Biederman detach_mounts(new_dentry); 4214bc27027aSMiklos Szeredi } 4215da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4216da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4217bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4218da1ce067SMiklos Szeredi else 4219da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4220da1ce067SMiklos Szeredi } 4221bc27027aSMiklos Szeredi out: 4222da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4223bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4224bc27027aSMiklos Szeredi else if (target) 4225bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4226bc27027aSMiklos Szeredi dput(new_dentry); 4227da1ce067SMiklos Szeredi if (!error) { 4228123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4229da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4230da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4231da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4232da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4233da1ce067SMiklos Szeredi } 4234da1ce067SMiklos Szeredi } 42350eeca283SRobert Love fsnotify_oldname_free(old_name); 42360eeca283SRobert Love 42371da177e4SLinus Torvalds return error; 42381da177e4SLinus Torvalds } 42394d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42401da177e4SLinus Torvalds 4241520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4242520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42431da177e4SLinus Torvalds { 42441da177e4SLinus Torvalds struct dentry *old_dir, *new_dir; 42451da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42461da177e4SLinus Torvalds struct dentry *trap; 42471da177e4SLinus Torvalds struct nameidata oldnd, newnd; 42488e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 424991a27b2aSJeff Layton struct filename *from; 425091a27b2aSJeff Layton struct filename *to; 4251c6a94284SJeff Layton unsigned int lookup_flags = 0; 4252c6a94284SJeff Layton bool should_retry = false; 42532ad94ae6SAl Viro int error; 4254520c8b16SMiklos Szeredi 42550d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4256da1ce067SMiklos Szeredi return -EINVAL; 4257da1ce067SMiklos Szeredi 42580d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42590d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4260520c8b16SMiklos Szeredi return -EINVAL; 4261520c8b16SMiklos Szeredi 42620d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42630d7a8555SMiklos Szeredi return -EPERM; 42640d7a8555SMiklos Szeredi 4265c6a94284SJeff Layton retry: 4266c6a94284SJeff Layton from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); 426791a27b2aSJeff Layton if (IS_ERR(from)) { 426891a27b2aSJeff Layton error = PTR_ERR(from); 42691da177e4SLinus Torvalds goto exit; 427091a27b2aSJeff Layton } 42711da177e4SLinus Torvalds 4272c6a94284SJeff Layton to = user_path_parent(newdfd, newname, &newnd, lookup_flags); 427391a27b2aSJeff Layton if (IS_ERR(to)) { 427491a27b2aSJeff Layton error = PTR_ERR(to); 42751da177e4SLinus Torvalds goto exit1; 427691a27b2aSJeff Layton } 42771da177e4SLinus Torvalds 42781da177e4SLinus Torvalds error = -EXDEV; 42794ac91378SJan Blunck if (oldnd.path.mnt != newnd.path.mnt) 42801da177e4SLinus Torvalds goto exit2; 42811da177e4SLinus Torvalds 42824ac91378SJan Blunck old_dir = oldnd.path.dentry; 42831da177e4SLinus Torvalds error = -EBUSY; 42841da177e4SLinus Torvalds if (oldnd.last_type != LAST_NORM) 42851da177e4SLinus Torvalds goto exit2; 42861da177e4SLinus Torvalds 42874ac91378SJan Blunck new_dir = newnd.path.dentry; 42880a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 42890a7c3937SMiklos Szeredi error = -EEXIST; 42901da177e4SLinus Torvalds if (newnd.last_type != LAST_NORM) 42911da177e4SLinus Torvalds goto exit2; 42921da177e4SLinus Torvalds 4293c30dabfeSJan Kara error = mnt_want_write(oldnd.path.mnt); 4294c30dabfeSJan Kara if (error) 4295c30dabfeSJan Kara goto exit2; 4296c30dabfeSJan Kara 42970612d9fbSOGAWA Hirofumi oldnd.flags &= ~LOOKUP_PARENT; 42980612d9fbSOGAWA Hirofumi newnd.flags &= ~LOOKUP_PARENT; 4299da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43004e9ed2f8SOGAWA Hirofumi newnd.flags |= LOOKUP_RENAME_TARGET; 43010612d9fbSOGAWA Hirofumi 43028e6d782cSJ. Bruce Fields retry_deleg: 43031da177e4SLinus Torvalds trap = lock_rename(new_dir, old_dir); 43041da177e4SLinus Torvalds 430549705b77SChristoph Hellwig old_dentry = lookup_hash(&oldnd); 43061da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43071da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43081da177e4SLinus Torvalds goto exit3; 43091da177e4SLinus Torvalds /* source must exist */ 43101da177e4SLinus Torvalds error = -ENOENT; 4311b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43121da177e4SLinus Torvalds goto exit4; 431349705b77SChristoph Hellwig new_dentry = lookup_hash(&newnd); 43141da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43151da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43161da177e4SLinus Torvalds goto exit4; 43170a7c3937SMiklos Szeredi error = -EEXIST; 43180a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43190a7c3937SMiklos Szeredi goto exit5; 4320da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4321da1ce067SMiklos Szeredi error = -ENOENT; 4322da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4323da1ce067SMiklos Szeredi goto exit5; 4324da1ce067SMiklos Szeredi 4325da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4326da1ce067SMiklos Szeredi error = -ENOTDIR; 4327da1ce067SMiklos Szeredi if (newnd.last.name[newnd.last.len]) 4328da1ce067SMiklos Szeredi goto exit5; 4329da1ce067SMiklos Szeredi } 4330da1ce067SMiklos Szeredi } 43310a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43320a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43330a7c3937SMiklos Szeredi error = -ENOTDIR; 43340a7c3937SMiklos Szeredi if (oldnd.last.name[oldnd.last.len]) 43350a7c3937SMiklos Szeredi goto exit5; 4336da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) 43370a7c3937SMiklos Szeredi goto exit5; 43380a7c3937SMiklos Szeredi } 43390a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43400a7c3937SMiklos Szeredi error = -EINVAL; 43410a7c3937SMiklos Szeredi if (old_dentry == trap) 43420a7c3937SMiklos Szeredi goto exit5; 43431da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4344da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43451da177e4SLinus Torvalds error = -ENOTEMPTY; 43461da177e4SLinus Torvalds if (new_dentry == trap) 43471da177e4SLinus Torvalds goto exit5; 43481da177e4SLinus Torvalds 4349be6d3e56SKentaro Takeda error = security_path_rename(&oldnd.path, old_dentry, 43500b3974ebSMiklos Szeredi &newnd.path, new_dentry, flags); 4351be6d3e56SKentaro Takeda if (error) 4352c30dabfeSJan Kara goto exit5; 43531da177e4SLinus Torvalds error = vfs_rename(old_dir->d_inode, old_dentry, 43548e6d782cSJ. Bruce Fields new_dir->d_inode, new_dentry, 4355520c8b16SMiklos Szeredi &delegated_inode, flags); 43561da177e4SLinus Torvalds exit5: 43571da177e4SLinus Torvalds dput(new_dentry); 43581da177e4SLinus Torvalds exit4: 43591da177e4SLinus Torvalds dput(old_dentry); 43601da177e4SLinus Torvalds exit3: 43611da177e4SLinus Torvalds unlock_rename(new_dir, old_dir); 43628e6d782cSJ. Bruce Fields if (delegated_inode) { 43638e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43648e6d782cSJ. Bruce Fields if (!error) 43658e6d782cSJ. Bruce Fields goto retry_deleg; 43668e6d782cSJ. Bruce Fields } 4367c30dabfeSJan Kara mnt_drop_write(oldnd.path.mnt); 43681da177e4SLinus Torvalds exit2: 4369c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4370c6a94284SJeff Layton should_retry = true; 43711d957f9bSJan Blunck path_put(&newnd.path); 43722ad94ae6SAl Viro putname(to); 43731da177e4SLinus Torvalds exit1: 43741d957f9bSJan Blunck path_put(&oldnd.path); 43751da177e4SLinus Torvalds putname(from); 4376c6a94284SJeff Layton if (should_retry) { 4377c6a94284SJeff Layton should_retry = false; 4378c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4379c6a94284SJeff Layton goto retry; 4380c6a94284SJeff Layton } 43812ad94ae6SAl Viro exit: 43821da177e4SLinus Torvalds return error; 43831da177e4SLinus Torvalds } 43841da177e4SLinus Torvalds 4385520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4386520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4387520c8b16SMiklos Szeredi { 4388520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4389520c8b16SMiklos Szeredi } 4390520c8b16SMiklos Szeredi 4391a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 43925590ff0dSUlrich Drepper { 4393520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43945590ff0dSUlrich Drepper } 43955590ff0dSUlrich Drepper 4396787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4397787fb6bcSMiklos Szeredi { 4398787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4399787fb6bcSMiklos Szeredi if (error) 4400787fb6bcSMiklos Szeredi return error; 4401787fb6bcSMiklos Szeredi 4402787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4403787fb6bcSMiklos Szeredi return -EPERM; 4404787fb6bcSMiklos Szeredi 4405787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4406787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4407787fb6bcSMiklos Szeredi } 4408787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4409787fb6bcSMiklos Szeredi 44105d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44111da177e4SLinus Torvalds { 44125d826c84SAl Viro int len = PTR_ERR(link); 44131da177e4SLinus Torvalds if (IS_ERR(link)) 44141da177e4SLinus Torvalds goto out; 44151da177e4SLinus Torvalds 44161da177e4SLinus Torvalds len = strlen(link); 44171da177e4SLinus Torvalds if (len > (unsigned) buflen) 44181da177e4SLinus Torvalds len = buflen; 44191da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44201da177e4SLinus Torvalds len = -EFAULT; 44211da177e4SLinus Torvalds out: 44221da177e4SLinus Torvalds return len; 44231da177e4SLinus Torvalds } 44245d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44251da177e4SLinus Torvalds 44261da177e4SLinus Torvalds /* 44271da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44281da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44291da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44301da177e4SLinus Torvalds */ 44311da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44321da177e4SLinus Torvalds { 44331da177e4SLinus Torvalds struct nameidata nd; 4434cc314eefSLinus Torvalds void *cookie; 4435694a1764SMarcin Slusarz int res; 4436cc314eefSLinus Torvalds 44371da177e4SLinus Torvalds nd.depth = 0; 4438cc314eefSLinus Torvalds cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); 4439694a1764SMarcin Slusarz if (IS_ERR(cookie)) 4440694a1764SMarcin Slusarz return PTR_ERR(cookie); 4441694a1764SMarcin Slusarz 44425d826c84SAl Viro res = readlink_copy(buffer, buflen, nd_get_link(&nd)); 44431da177e4SLinus Torvalds if (dentry->d_inode->i_op->put_link) 4444cc314eefSLinus Torvalds dentry->d_inode->i_op->put_link(dentry, &nd, cookie); 4445694a1764SMarcin Slusarz return res; 44461da177e4SLinus Torvalds } 44474d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44481da177e4SLinus Torvalds 44491da177e4SLinus Torvalds /* get the link contents into pagecache */ 44501da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44511da177e4SLinus Torvalds { 4452ebd09abbSDuane Griffin char *kaddr; 44531da177e4SLinus Torvalds struct page *page; 44541da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4455090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44561da177e4SLinus Torvalds if (IS_ERR(page)) 44576fe6900eSNick Piggin return (char*)page; 44581da177e4SLinus Torvalds *ppage = page; 4459ebd09abbSDuane Griffin kaddr = kmap(page); 4460ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4461ebd09abbSDuane Griffin return kaddr; 44621da177e4SLinus Torvalds } 44631da177e4SLinus Torvalds 44641da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44651da177e4SLinus Torvalds { 44661da177e4SLinus Torvalds struct page *page = NULL; 44675d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44681da177e4SLinus Torvalds if (page) { 44691da177e4SLinus Torvalds kunmap(page); 44701da177e4SLinus Torvalds page_cache_release(page); 44711da177e4SLinus Torvalds } 44721da177e4SLinus Torvalds return res; 44731da177e4SLinus Torvalds } 44744d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44751da177e4SLinus Torvalds 4476cc314eefSLinus Torvalds void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) 44771da177e4SLinus Torvalds { 4478cc314eefSLinus Torvalds struct page *page = NULL; 44791da177e4SLinus Torvalds nd_set_link(nd, page_getlink(dentry, &page)); 4480cc314eefSLinus Torvalds return page; 44811da177e4SLinus Torvalds } 44824d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 44831da177e4SLinus Torvalds 4484cc314eefSLinus Torvalds void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 44851da177e4SLinus Torvalds { 4486cc314eefSLinus Torvalds struct page *page = cookie; 4487cc314eefSLinus Torvalds 4488cc314eefSLinus Torvalds if (page) { 44891da177e4SLinus Torvalds kunmap(page); 44901da177e4SLinus Torvalds page_cache_release(page); 44911da177e4SLinus Torvalds } 44921da177e4SLinus Torvalds } 44934d359507SAl Viro EXPORT_SYMBOL(page_put_link); 44941da177e4SLinus Torvalds 449554566b2cSNick Piggin /* 449654566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 449754566b2cSNick Piggin */ 449854566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 44991da177e4SLinus Torvalds { 45001da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45010adb25d2SKirill Korotaev struct page *page; 4502afddba49SNick Piggin void *fsdata; 4503beb497abSDmitriy Monakhov int err; 45041da177e4SLinus Torvalds char *kaddr; 450554566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 450654566b2cSNick Piggin if (nofs) 450754566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45081da177e4SLinus Torvalds 45097e53cac4SNeilBrown retry: 4510afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 451154566b2cSNick Piggin flags, &page, &fsdata); 45121da177e4SLinus Torvalds if (err) 4513afddba49SNick Piggin goto fail; 4514afddba49SNick Piggin 4515e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45161da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4517e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4518afddba49SNick Piggin 4519afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4520afddba49SNick Piggin page, fsdata); 45211da177e4SLinus Torvalds if (err < 0) 45221da177e4SLinus Torvalds goto fail; 4523afddba49SNick Piggin if (err < len-1) 4524afddba49SNick Piggin goto retry; 4525afddba49SNick Piggin 45261da177e4SLinus Torvalds mark_inode_dirty(inode); 45271da177e4SLinus Torvalds return 0; 45281da177e4SLinus Torvalds fail: 45291da177e4SLinus Torvalds return err; 45301da177e4SLinus Torvalds } 45314d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45321da177e4SLinus Torvalds 45330adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45340adb25d2SKirill Korotaev { 45350adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 453654566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45370adb25d2SKirill Korotaev } 45384d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45390adb25d2SKirill Korotaev 454092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45411da177e4SLinus Torvalds .readlink = generic_readlink, 45421da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45431da177e4SLinus Torvalds .put_link = page_put_link, 45441da177e4SLinus Torvalds }; 45451da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4546