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 */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 498caa85634SAl Viro union { 4991f55a6ecSAl Viro struct qstr last; 500caa85634SAl Viro struct path link; 501caa85634SAl Viro }; 5021f55a6ecSAl Viro struct path root; 5031f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5041f55a6ecSAl Viro unsigned int flags; 5051f55a6ecSAl Viro unsigned seq, m_seq; 5061f55a6ecSAl Viro int last_type; 5071f55a6ecSAl Viro unsigned depth; 508756daf26SNeilBrown int total_link_count; 5095e53084dSAl Viro struct file *base; 510697fc6caSAl Viro struct saved { 511697fc6caSAl Viro struct path link; 512697fc6caSAl Viro void *cookie; 513697fc6caSAl Viro const char *name; 514894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5151f55a6ecSAl Viro }; 5161f55a6ecSAl Viro 517756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 518894bc8c4SAl Viro { 519756daf26SNeilBrown struct nameidata *old = current->nameidata; 520756daf26SNeilBrown p->stack = p->internal; 521756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 522756daf26SNeilBrown current->nameidata = p; 523756daf26SNeilBrown return old; 524894bc8c4SAl Viro } 525894bc8c4SAl Viro 526756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 527894bc8c4SAl Viro { 528756daf26SNeilBrown struct nameidata *now = current->nameidata; 529756daf26SNeilBrown 530756daf26SNeilBrown current->nameidata = old; 531756daf26SNeilBrown if (old) 532756daf26SNeilBrown old->total_link_count = now->total_link_count; 533756daf26SNeilBrown if (now->stack != now->internal) { 534756daf26SNeilBrown kfree(now->stack); 535756daf26SNeilBrown now->stack = now->internal; 536894bc8c4SAl Viro } 537894bc8c4SAl Viro } 538894bc8c4SAl Viro 539894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 540894bc8c4SAl Viro { 541e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 542894bc8c4SAl Viro GFP_KERNEL); 543894bc8c4SAl Viro if (unlikely(!p)) 544894bc8c4SAl Viro return -ENOMEM; 545894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 546894bc8c4SAl Viro nd->stack = p; 547894bc8c4SAl Viro return 0; 548894bc8c4SAl Viro } 549894bc8c4SAl Viro 550894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 551894bc8c4SAl Viro { 552da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 553894bc8c4SAl Viro return 0; 554894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 555894bc8c4SAl Viro return 0; 556894bc8c4SAl Viro return __nd_alloc_stack(nd); 557894bc8c4SAl Viro } 558894bc8c4SAl Viro 55919660af7SAl Viro /* 56031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 56119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 56219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 56319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 56419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 56519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 56619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 56719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 56831e6b01fSNick Piggin */ 56931e6b01fSNick Piggin 57031e6b01fSNick Piggin /** 57119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 57219660af7SAl Viro * @nd: nameidata pathwalk data 57319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 57439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 57531e6b01fSNick Piggin * 57619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 57719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 57819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 57931e6b01fSNick Piggin */ 58019660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 58131e6b01fSNick Piggin { 58231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 58331e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 58431e6b01fSNick Piggin 58531e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 586e5c832d5SLinus Torvalds 587e5c832d5SLinus Torvalds /* 58848a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 58948a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 59048a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 59148a066e7SAl Viro * before returning. Do vfsmount first; if dentry 59248a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 59348a066e7SAl Viro * and rely on dput(NULL) being a no-op. 594e5c832d5SLinus Torvalds */ 59548a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 596e5c832d5SLinus Torvalds return -ECHILD; 597e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 59815570086SLinus Torvalds 59948a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 60048a066e7SAl Viro nd->path.dentry = NULL; 601d870b4a1SAl Viro goto out; 60248a066e7SAl Viro } 60348a066e7SAl Viro 60415570086SLinus Torvalds /* 60515570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 60615570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 60715570086SLinus Torvalds * 60815570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 60915570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 61015570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 61115570086SLinus Torvalds * since we checked the sequence number of the parent after we got 61215570086SLinus Torvalds * the child sequence number. So we know the parent must still 61315570086SLinus Torvalds * be valid if the child sequence number is still valid. 61415570086SLinus Torvalds */ 61519660af7SAl Viro if (!dentry) { 616e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 617e5c832d5SLinus Torvalds goto out; 61819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 61919660af7SAl Viro } else { 620e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 621e5c832d5SLinus Torvalds goto out; 622e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 623e5c832d5SLinus Torvalds goto drop_dentry; 62419660af7SAl Viro } 625e5c832d5SLinus Torvalds 626e5c832d5SLinus Torvalds /* 627e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 628e5c832d5SLinus Torvalds * still valid and get it if required. 629e5c832d5SLinus Torvalds */ 630e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 631e5c832d5SLinus Torvalds spin_lock(&fs->lock); 632e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 633e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 63431e6b01fSNick Piggin path_get(&nd->root); 63531e6b01fSNick Piggin spin_unlock(&fs->lock); 63631e6b01fSNick Piggin } 63731e6b01fSNick Piggin 6388b61e74fSAl Viro rcu_read_unlock(); 63931e6b01fSNick Piggin return 0; 64019660af7SAl Viro 641e5c832d5SLinus Torvalds unlock_and_drop_dentry: 64231e6b01fSNick Piggin spin_unlock(&fs->lock); 643e5c832d5SLinus Torvalds drop_dentry: 6448b61e74fSAl Viro rcu_read_unlock(); 645e5c832d5SLinus Torvalds dput(dentry); 646d0d27277SLinus Torvalds goto drop_root_mnt; 647e5c832d5SLinus Torvalds out: 6488b61e74fSAl Viro rcu_read_unlock(); 649d0d27277SLinus Torvalds drop_root_mnt: 650d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 651d0d27277SLinus Torvalds nd->root.mnt = NULL; 65231e6b01fSNick Piggin return -ECHILD; 65331e6b01fSNick Piggin } 65431e6b01fSNick Piggin 6554ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 65634286d66SNick Piggin { 6574ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 65834286d66SNick Piggin } 65934286d66SNick Piggin 6609f1fafeeSAl Viro /** 6619f1fafeeSAl Viro * complete_walk - successful completion of path walk 6629f1fafeeSAl Viro * @nd: pointer nameidata 66339159de2SJeff Layton * 6649f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6659f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6669f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6679f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6689f1fafeeSAl Viro * need to drop nd->path. 66939159de2SJeff Layton */ 6709f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 67139159de2SJeff Layton { 67216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 67339159de2SJeff Layton int status; 67439159de2SJeff Layton 6759f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6769f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6779f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6789f1fafeeSAl Viro nd->root.mnt = NULL; 67915570086SLinus Torvalds 68048a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6818b61e74fSAl Viro rcu_read_unlock(); 68248a066e7SAl Viro return -ECHILD; 68348a066e7SAl Viro } 684e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6858b61e74fSAl Viro rcu_read_unlock(); 68648a066e7SAl Viro mntput(nd->path.mnt); 6879f1fafeeSAl Viro return -ECHILD; 6889f1fafeeSAl Viro } 689e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6908b61e74fSAl Viro rcu_read_unlock(); 691e5c832d5SLinus Torvalds dput(dentry); 69248a066e7SAl Viro mntput(nd->path.mnt); 693e5c832d5SLinus Torvalds return -ECHILD; 694e5c832d5SLinus Torvalds } 6958b61e74fSAl Viro rcu_read_unlock(); 6969f1fafeeSAl Viro } 6979f1fafeeSAl Viro 69816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 69939159de2SJeff Layton return 0; 70039159de2SJeff Layton 701ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 70216c2cd71SAl Viro return 0; 70316c2cd71SAl Viro 704ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 70539159de2SJeff Layton if (status > 0) 70639159de2SJeff Layton return 0; 70739159de2SJeff Layton 70816c2cd71SAl Viro if (!status) 70939159de2SJeff Layton status = -ESTALE; 71016c2cd71SAl Viro 7119f1fafeeSAl Viro path_put(&nd->path); 71239159de2SJeff Layton return status; 71339159de2SJeff Layton } 71439159de2SJeff Layton 7152a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7162a737871SAl Viro { 717f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7182a737871SAl Viro } 7192a737871SAl Viro 7207bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 72131e6b01fSNick Piggin { 72231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7237bd88377SAl Viro unsigned seq, res; 724c28cc364SNick Piggin 725c28cc364SNick Piggin do { 726c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 72731e6b01fSNick Piggin nd->root = fs->root; 7287bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 729c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7307bd88377SAl Viro return res; 73131e6b01fSNick Piggin } 73231e6b01fSNick Piggin 7331d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 734051d3812SIan Kent { 735051d3812SIan Kent dput(path->dentry); 7364ac91378SJan Blunck if (path->mnt != nd->path.mnt) 737051d3812SIan Kent mntput(path->mnt); 738051d3812SIan Kent } 739051d3812SIan Kent 7407b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7417b9337aaSNick Piggin struct nameidata *nd) 742051d3812SIan Kent { 74331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7444ac91378SJan Blunck dput(nd->path.dentry); 74531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7464ac91378SJan Blunck mntput(nd->path.mnt); 7479a229683SHuang Shijie } 74831e6b01fSNick Piggin nd->path.mnt = path->mnt; 7494ac91378SJan Blunck nd->path.dentry = path->dentry; 750051d3812SIan Kent } 751051d3812SIan Kent 752b5fb63c1SChristoph Hellwig /* 753b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 754b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 755b5fb63c1SChristoph Hellwig */ 756b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 757b5fb63c1SChristoph Hellwig { 758b5fb63c1SChristoph Hellwig path_put(&nd->path); 759b5fb63c1SChristoph Hellwig 760b5fb63c1SChristoph Hellwig nd->path = *path; 761b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 762b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 763b5fb63c1SChristoph Hellwig } 764b5fb63c1SChristoph Hellwig 765b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 766574197e0SAl Viro { 76721c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 768b9ff4429SAl Viro struct inode *inode = last->link.dentry->d_inode; 769b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 770b9ff4429SAl Viro inode->i_op->put_link(last->link.dentry, last->cookie); 771b9ff4429SAl Viro path_put(&last->link); 772574197e0SAl Viro } 773574197e0SAl Viro 774561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 775561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 776800179c9SKees Cook 777800179c9SKees Cook /** 778800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 779800179c9SKees Cook * @link: The path of the symlink 78055852635SRandy Dunlap * @nd: nameidata pathwalk data 781800179c9SKees Cook * 782800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 783800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 784800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 785800179c9SKees Cook * processes from failing races against path names that may change out 786800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 787800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 788800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 789800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 790800179c9SKees Cook * 791800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 792800179c9SKees Cook */ 793800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 794800179c9SKees Cook { 795800179c9SKees Cook const struct inode *inode; 796800179c9SKees Cook const struct inode *parent; 797800179c9SKees Cook 798800179c9SKees Cook if (!sysctl_protected_symlinks) 799800179c9SKees Cook return 0; 800800179c9SKees Cook 801800179c9SKees Cook /* Allowed if owner and follower match. */ 802800179c9SKees Cook inode = link->dentry->d_inode; 80381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 804800179c9SKees Cook return 0; 805800179c9SKees Cook 806800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 807800179c9SKees Cook parent = nd->path.dentry->d_inode; 808800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 809800179c9SKees Cook return 0; 810800179c9SKees Cook 811800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 81281abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 813800179c9SKees Cook return 0; 814800179c9SKees Cook 815ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 816800179c9SKees Cook path_put_conditional(link, nd); 817800179c9SKees Cook path_put(&nd->path); 818800179c9SKees Cook return -EACCES; 819800179c9SKees Cook } 820800179c9SKees Cook 821800179c9SKees Cook /** 822800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 823800179c9SKees Cook * @inode: the source inode to hardlink from 824800179c9SKees Cook * 825800179c9SKees Cook * Return false if at least one of the following conditions: 826800179c9SKees Cook * - inode is not a regular file 827800179c9SKees Cook * - inode is setuid 828800179c9SKees Cook * - inode is setgid and group-exec 829800179c9SKees Cook * - access failure for read and write 830800179c9SKees Cook * 831800179c9SKees Cook * Otherwise returns true. 832800179c9SKees Cook */ 833800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 834800179c9SKees Cook { 835800179c9SKees Cook umode_t mode = inode->i_mode; 836800179c9SKees Cook 837800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 838800179c9SKees Cook if (!S_ISREG(mode)) 839800179c9SKees Cook return false; 840800179c9SKees Cook 841800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 842800179c9SKees Cook if (mode & S_ISUID) 843800179c9SKees Cook return false; 844800179c9SKees Cook 845800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 846800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 847800179c9SKees Cook return false; 848800179c9SKees Cook 849800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 850800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 851800179c9SKees Cook return false; 852800179c9SKees Cook 853800179c9SKees Cook return true; 854800179c9SKees Cook } 855800179c9SKees Cook 856800179c9SKees Cook /** 857800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 858800179c9SKees Cook * @link: the source to hardlink from 859800179c9SKees Cook * 860800179c9SKees Cook * Block hardlink when all of: 861800179c9SKees Cook * - sysctl_protected_hardlinks enabled 862800179c9SKees Cook * - fsuid does not match inode 863800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 864800179c9SKees Cook * - not CAP_FOWNER 865800179c9SKees Cook * 866800179c9SKees Cook * Returns 0 if successful, -ve on error. 867800179c9SKees Cook */ 868800179c9SKees Cook static int may_linkat(struct path *link) 869800179c9SKees Cook { 870800179c9SKees Cook const struct cred *cred; 871800179c9SKees Cook struct inode *inode; 872800179c9SKees Cook 873800179c9SKees Cook if (!sysctl_protected_hardlinks) 874800179c9SKees Cook return 0; 875800179c9SKees Cook 876800179c9SKees Cook cred = current_cred(); 877800179c9SKees Cook inode = link->dentry->d_inode; 878800179c9SKees Cook 879800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 880800179c9SKees Cook * otherwise, it must be a safe source. 881800179c9SKees Cook */ 88281abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 883800179c9SKees Cook capable(CAP_FOWNER)) 884800179c9SKees Cook return 0; 885800179c9SKees Cook 886a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 887800179c9SKees Cook return -EPERM; 888800179c9SKees Cook } 889800179c9SKees Cook 8903b2e7f75SAl Viro static __always_inline 8913b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8921da177e4SLinus Torvalds { 8933b2e7f75SAl Viro struct saved *last = nd->stack + nd->depth; 8943b2e7f75SAl Viro struct dentry *dentry = nd->link.dentry; 8950a959df5SAl Viro struct inode *inode = dentry->d_inode; 8966d7b5aaeSAl Viro int error; 8970a959df5SAl Viro const char *res; 8981da177e4SLinus Torvalds 899844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 900844a3917SAl Viro 9013b2e7f75SAl Viro if (nd->link.mnt == nd->path.mnt) 9023b2e7f75SAl Viro mntget(nd->link.mnt); 9030e794589SAl Viro 9043b2e7f75SAl Viro last->link = nd->link; 9053b2e7f75SAl Viro last->cookie = NULL; 9066d7b5aaeSAl Viro 907574197e0SAl Viro cond_resched(); 908574197e0SAl Viro 9093b2e7f75SAl Viro touch_atime(&last->link); 910cd4e91d3SAl Viro 91137882db0SNeilBrown error = security_inode_follow_link(dentry); 9120a959df5SAl Viro res = ERR_PTR(error); 9136d7b5aaeSAl Viro if (error) 9140a959df5SAl Viro goto out; 91536f3b4f6SAl Viro 91686acdca1SAl Viro nd->last_type = LAST_BIND; 917d4dee48bSAl Viro res = inode->i_link; 918d4dee48bSAl Viro if (!res) { 9193b2e7f75SAl Viro res = inode->i_op->follow_link(dentry, &last->cookie, nd); 9200a959df5SAl Viro if (IS_ERR(res)) { 9210a959df5SAl Viro out: 9223b2e7f75SAl Viro path_put(&last->link); 9230fd889d5SAl Viro return res; 9240a959df5SAl Viro } 925d4dee48bSAl Viro } 9260fd889d5SAl Viro nd->depth++; 9270a959df5SAl Viro return res; 9280a959df5SAl Viro } 9296d7b5aaeSAl Viro 93031e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 93131e6b01fSNick Piggin { 9320714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9330714a533SAl Viro struct mount *parent; 93431e6b01fSNick Piggin struct dentry *mountpoint; 93531e6b01fSNick Piggin 9360714a533SAl Viro parent = mnt->mnt_parent; 9370714a533SAl Viro if (&parent->mnt == path->mnt) 93831e6b01fSNick Piggin return 0; 939a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 94031e6b01fSNick Piggin path->dentry = mountpoint; 9410714a533SAl Viro path->mnt = &parent->mnt; 94231e6b01fSNick Piggin return 1; 94331e6b01fSNick Piggin } 94431e6b01fSNick Piggin 945f015f126SDavid Howells /* 946f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 947f015f126SDavid Howells * 948f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 949f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 950f015f126SDavid Howells * Up is towards /. 951f015f126SDavid Howells * 952f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 953f015f126SDavid Howells * root. 954f015f126SDavid Howells */ 955bab77ebfSAl Viro int follow_up(struct path *path) 9561da177e4SLinus Torvalds { 9570714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9580714a533SAl Viro struct mount *parent; 9591da177e4SLinus Torvalds struct dentry *mountpoint; 96099b7db7bSNick Piggin 96148a066e7SAl Viro read_seqlock_excl(&mount_lock); 9620714a533SAl Viro parent = mnt->mnt_parent; 9633c0a6163SAl Viro if (parent == mnt) { 96448a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9651da177e4SLinus Torvalds return 0; 9661da177e4SLinus Torvalds } 9670714a533SAl Viro mntget(&parent->mnt); 968a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 96948a066e7SAl Viro read_sequnlock_excl(&mount_lock); 970bab77ebfSAl Viro dput(path->dentry); 971bab77ebfSAl Viro path->dentry = mountpoint; 972bab77ebfSAl Viro mntput(path->mnt); 9730714a533SAl Viro path->mnt = &parent->mnt; 9741da177e4SLinus Torvalds return 1; 9751da177e4SLinus Torvalds } 9764d359507SAl Viro EXPORT_SYMBOL(follow_up); 9771da177e4SLinus Torvalds 978b5c84bf6SNick Piggin /* 9799875cf80SDavid Howells * Perform an automount 9809875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9819875cf80SDavid Howells * were called with. 9821da177e4SLinus Torvalds */ 983756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 9849875cf80SDavid Howells bool *need_mntput) 98531e6b01fSNick Piggin { 9869875cf80SDavid Howells struct vfsmount *mnt; 987ea5b778aSDavid Howells int err; 9889875cf80SDavid Howells 9899875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9909875cf80SDavid Howells return -EREMOTE; 9919875cf80SDavid Howells 9920ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9930ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9940ec26fd0SMiklos Szeredi * the name. 9950ec26fd0SMiklos Szeredi * 9960ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9975a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9980ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9990ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 10000ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 10010ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 10025a30d8a2SDavid Howells */ 1003756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1004d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 10055a30d8a2SDavid Howells path->dentry->d_inode) 10069875cf80SDavid Howells return -EISDIR; 10070ec26fd0SMiklos Szeredi 1008756daf26SNeilBrown nd->total_link_count++; 1009756daf26SNeilBrown if (nd->total_link_count >= 40) 10109875cf80SDavid Howells return -ELOOP; 10119875cf80SDavid Howells 10129875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10139875cf80SDavid Howells if (IS_ERR(mnt)) { 10149875cf80SDavid Howells /* 10159875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10169875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10179875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10189875cf80SDavid Howells * 10199875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10209875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10219875cf80SDavid Howells * the path is inaccessible and we should say so. 10229875cf80SDavid Howells */ 1023756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10249875cf80SDavid Howells return -EREMOTE; 10259875cf80SDavid Howells return PTR_ERR(mnt); 102631e6b01fSNick Piggin } 1027ea5b778aSDavid Howells 10289875cf80SDavid Howells if (!mnt) /* mount collision */ 10299875cf80SDavid Howells return 0; 10309875cf80SDavid Howells 10318aef1884SAl Viro if (!*need_mntput) { 10328aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10338aef1884SAl Viro mntget(path->mnt); 10348aef1884SAl Viro *need_mntput = true; 10358aef1884SAl Viro } 103619a167afSAl Viro err = finish_automount(mnt, path); 1037ea5b778aSDavid Howells 1038ea5b778aSDavid Howells switch (err) { 1039ea5b778aSDavid Howells case -EBUSY: 1040ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 104119a167afSAl Viro return 0; 1042ea5b778aSDavid Howells case 0: 10438aef1884SAl Viro path_put(path); 10449875cf80SDavid Howells path->mnt = mnt; 10459875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10469875cf80SDavid Howells return 0; 104719a167afSAl Viro default: 104819a167afSAl Viro return err; 10499875cf80SDavid Howells } 105019a167afSAl Viro 1051ea5b778aSDavid Howells } 10529875cf80SDavid Howells 10539875cf80SDavid Howells /* 10549875cf80SDavid Howells * Handle a dentry that is managed in some way. 1055cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10569875cf80SDavid Howells * - Flagged as mountpoint 10579875cf80SDavid Howells * - Flagged as automount point 10589875cf80SDavid Howells * 10599875cf80SDavid Howells * This may only be called in refwalk mode. 10609875cf80SDavid Howells * 10619875cf80SDavid Howells * Serialization is taken care of in namespace.c 10629875cf80SDavid Howells */ 1063756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 10649875cf80SDavid Howells { 10658aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10669875cf80SDavid Howells unsigned managed; 10679875cf80SDavid Howells bool need_mntput = false; 10688aef1884SAl Viro int ret = 0; 10699875cf80SDavid Howells 10709875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10719875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10729875cf80SDavid Howells * the components of that value change under us */ 10739875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10749875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10759875cf80SDavid Howells unlikely(managed != 0)) { 1076cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1077cc53ce53SDavid Howells * being held. */ 1078cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1079cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1080cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10811aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1082cc53ce53SDavid Howells if (ret < 0) 10838aef1884SAl Viro break; 1084cc53ce53SDavid Howells } 1085cc53ce53SDavid Howells 10869875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10879875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10889875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10899875cf80SDavid Howells if (mounted) { 10909875cf80SDavid Howells dput(path->dentry); 10919875cf80SDavid Howells if (need_mntput) 1092463ffb2eSAl Viro mntput(path->mnt); 1093463ffb2eSAl Viro path->mnt = mounted; 1094463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10959875cf80SDavid Howells need_mntput = true; 10969875cf80SDavid Howells continue; 1097463ffb2eSAl Viro } 1098463ffb2eSAl Viro 10999875cf80SDavid Howells /* Something is mounted on this dentry in another 11009875cf80SDavid Howells * namespace and/or whatever was mounted there in this 110148a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 110248a066e7SAl Viro * get it */ 11031da177e4SLinus Torvalds } 11049875cf80SDavid Howells 11059875cf80SDavid Howells /* Handle an automount point */ 11069875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1107756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 11089875cf80SDavid Howells if (ret < 0) 11098aef1884SAl Viro break; 11109875cf80SDavid Howells continue; 11119875cf80SDavid Howells } 11129875cf80SDavid Howells 11139875cf80SDavid Howells /* We didn't change the current path point */ 11149875cf80SDavid Howells break; 11159875cf80SDavid Howells } 11168aef1884SAl Viro 11178aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11188aef1884SAl Viro mntput(path->mnt); 11198aef1884SAl Viro if (ret == -EISDIR) 11208aef1884SAl Viro ret = 0; 11218402752eSAl Viro if (need_mntput) 11228402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11238402752eSAl Viro if (unlikely(ret < 0)) 11248402752eSAl Viro path_put_conditional(path, nd); 11258402752eSAl Viro return ret; 11261da177e4SLinus Torvalds } 11271da177e4SLinus Torvalds 1128cc53ce53SDavid Howells int follow_down_one(struct path *path) 11291da177e4SLinus Torvalds { 11301da177e4SLinus Torvalds struct vfsmount *mounted; 11311da177e4SLinus Torvalds 11321c755af4SAl Viro mounted = lookup_mnt(path); 11331da177e4SLinus Torvalds if (mounted) { 11349393bd07SAl Viro dput(path->dentry); 11359393bd07SAl Viro mntput(path->mnt); 11369393bd07SAl Viro path->mnt = mounted; 11379393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11381da177e4SLinus Torvalds return 1; 11391da177e4SLinus Torvalds } 11401da177e4SLinus Torvalds return 0; 11411da177e4SLinus Torvalds } 11424d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11431da177e4SLinus Torvalds 1144b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 114562a7375eSIan Kent { 1146b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1147b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 114862a7375eSIan Kent } 114962a7375eSIan Kent 11509875cf80SDavid Howells /* 1151287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1152287548e4SAl Viro * we meet a managed dentry that would need blocking. 11539875cf80SDavid Howells */ 11549875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1155287548e4SAl Viro struct inode **inode) 11569875cf80SDavid Howells { 115762a7375eSIan Kent for (;;) { 1158c7105365SAl Viro struct mount *mounted; 115962a7375eSIan Kent /* 116062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 116162a7375eSIan Kent * that wants to block transit. 116262a7375eSIan Kent */ 1163b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1164b8faf035SNeilBrown case -ECHILD: 1165b8faf035SNeilBrown default: 1166ab90911fSDavid Howells return false; 1167b8faf035SNeilBrown case -EISDIR: 1168b8faf035SNeilBrown return true; 1169b8faf035SNeilBrown case 0: 1170b8faf035SNeilBrown break; 1171b8faf035SNeilBrown } 117262a7375eSIan Kent 117362a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1174b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 117562a7375eSIan Kent 1176474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11779875cf80SDavid Howells if (!mounted) 11789875cf80SDavid Howells break; 1179c7105365SAl Viro path->mnt = &mounted->mnt; 1180c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1181a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11829875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 118359430262SLinus Torvalds /* 118459430262SLinus Torvalds * Update the inode too. We don't need to re-check the 118559430262SLinus Torvalds * dentry sequence number here after this d_inode read, 118659430262SLinus Torvalds * because a mount-point is always pinned. 118759430262SLinus Torvalds */ 118859430262SLinus Torvalds *inode = path->dentry->d_inode; 11899875cf80SDavid Howells } 1190f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1191b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1192287548e4SAl Viro } 1193287548e4SAl Viro 119431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 119531e6b01fSNick Piggin { 11964023bfc9SAl Viro struct inode *inode = nd->inode; 11977bd88377SAl Viro if (!nd->root.mnt) 119831e6b01fSNick Piggin set_root_rcu(nd); 119931e6b01fSNick Piggin 120031e6b01fSNick Piggin while (1) { 120131e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 120231e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 120331e6b01fSNick Piggin break; 120431e6b01fSNick Piggin } 120531e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 120631e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 120731e6b01fSNick Piggin struct dentry *parent = old->d_parent; 120831e6b01fSNick Piggin unsigned seq; 120931e6b01fSNick Piggin 12104023bfc9SAl Viro inode = parent->d_inode; 121131e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 121231e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1213ef7562d5SAl Viro goto failed; 121431e6b01fSNick Piggin nd->path.dentry = parent; 121531e6b01fSNick Piggin nd->seq = seq; 121631e6b01fSNick Piggin break; 121731e6b01fSNick Piggin } 121831e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 121931e6b01fSNick Piggin break; 12204023bfc9SAl Viro inode = nd->path.dentry->d_inode; 122131e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 122231e6b01fSNick Piggin } 1223b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1224b37199e6SAl Viro struct mount *mounted; 1225b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1226b37199e6SAl Viro if (!mounted) 1227b37199e6SAl Viro break; 1228b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1229b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12304023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1231b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1232f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1233b37199e6SAl Viro goto failed; 1234b37199e6SAl Viro } 12354023bfc9SAl Viro nd->inode = inode; 123631e6b01fSNick Piggin return 0; 1237ef7562d5SAl Viro 1238ef7562d5SAl Viro failed: 1239ef7562d5SAl Viro return -ECHILD; 124031e6b01fSNick Piggin } 124131e6b01fSNick Piggin 12429875cf80SDavid Howells /* 1243cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1244cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1245cc53ce53SDavid Howells * caller is permitted to proceed or not. 1246cc53ce53SDavid Howells */ 12477cc90cc3SAl Viro int follow_down(struct path *path) 1248cc53ce53SDavid Howells { 1249cc53ce53SDavid Howells unsigned managed; 1250cc53ce53SDavid Howells int ret; 1251cc53ce53SDavid Howells 1252cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1253cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1254cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1255cc53ce53SDavid Howells * being held. 1256cc53ce53SDavid Howells * 1257cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1258cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1259cc53ce53SDavid Howells * other than its daemon the right to mount on its 1260cc53ce53SDavid Howells * superstructure. 1261cc53ce53SDavid Howells * 1262cc53ce53SDavid Howells * The filesystem may sleep at this point. 1263cc53ce53SDavid Howells */ 1264cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1265cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1266cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1267ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12681aed3e42SAl Viro path->dentry, false); 1269cc53ce53SDavid Howells if (ret < 0) 1270cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1271cc53ce53SDavid Howells } 1272cc53ce53SDavid Howells 1273cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1274cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1275cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1276cc53ce53SDavid Howells if (!mounted) 1277cc53ce53SDavid Howells break; 1278cc53ce53SDavid Howells dput(path->dentry); 1279cc53ce53SDavid Howells mntput(path->mnt); 1280cc53ce53SDavid Howells path->mnt = mounted; 1281cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1282cc53ce53SDavid Howells continue; 1283cc53ce53SDavid Howells } 1284cc53ce53SDavid Howells 1285cc53ce53SDavid Howells /* Don't handle automount points here */ 1286cc53ce53SDavid Howells break; 1287cc53ce53SDavid Howells } 1288cc53ce53SDavid Howells return 0; 1289cc53ce53SDavid Howells } 12904d359507SAl Viro EXPORT_SYMBOL(follow_down); 1291cc53ce53SDavid Howells 1292cc53ce53SDavid Howells /* 12939875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12949875cf80SDavid Howells */ 12959875cf80SDavid Howells static void follow_mount(struct path *path) 12969875cf80SDavid Howells { 12979875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12989875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12999875cf80SDavid Howells if (!mounted) 13009875cf80SDavid Howells break; 13019875cf80SDavid Howells dput(path->dentry); 13029875cf80SDavid Howells mntput(path->mnt); 13039875cf80SDavid Howells path->mnt = mounted; 13049875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13059875cf80SDavid Howells } 13069875cf80SDavid Howells } 13079875cf80SDavid Howells 130831e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 13091da177e4SLinus Torvalds { 13107bd88377SAl Viro if (!nd->root.mnt) 13112a737871SAl Viro set_root(nd); 1312e518ddb7SAndreas Mohr 13131da177e4SLinus Torvalds while(1) { 13144ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13151da177e4SLinus Torvalds 13162a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13172a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13181da177e4SLinus Torvalds break; 13191da177e4SLinus Torvalds } 13204ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13213088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13223088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13231da177e4SLinus Torvalds dput(old); 13241da177e4SLinus Torvalds break; 13251da177e4SLinus Torvalds } 13263088dd70SAl Viro if (!follow_up(&nd->path)) 13271da177e4SLinus Torvalds break; 13281da177e4SLinus Torvalds } 132979ed0226SAl Viro follow_mount(&nd->path); 133031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13311da177e4SLinus Torvalds } 13321da177e4SLinus Torvalds 13331da177e4SLinus Torvalds /* 1334bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1335bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1336bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1337bad61189SMiklos Szeredi * 1338bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1339baa03890SNick Piggin */ 1340bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1341201f956eSAl Viro unsigned int flags, bool *need_lookup) 1342baa03890SNick Piggin { 1343baa03890SNick Piggin struct dentry *dentry; 1344bad61189SMiklos Szeredi int error; 1345baa03890SNick Piggin 1346bad61189SMiklos Szeredi *need_lookup = false; 1347bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1348bad61189SMiklos Szeredi if (dentry) { 134939e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1350201f956eSAl Viro error = d_revalidate(dentry, flags); 1351bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1352bad61189SMiklos Szeredi if (error < 0) { 1353bad61189SMiklos Szeredi dput(dentry); 1354bad61189SMiklos Szeredi return ERR_PTR(error); 13555542aa2fSEric W. Biederman } else { 13565542aa2fSEric W. Biederman d_invalidate(dentry); 1357bad61189SMiklos Szeredi dput(dentry); 1358bad61189SMiklos Szeredi dentry = NULL; 1359bad61189SMiklos Szeredi } 1360bad61189SMiklos Szeredi } 1361bad61189SMiklos Szeredi } 1362bad61189SMiklos Szeredi } 1363baa03890SNick Piggin 1364bad61189SMiklos Szeredi if (!dentry) { 1365bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1366baa03890SNick Piggin if (unlikely(!dentry)) 1367baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1368baa03890SNick Piggin 1369bad61189SMiklos Szeredi *need_lookup = true; 1370baa03890SNick Piggin } 1371baa03890SNick Piggin return dentry; 1372baa03890SNick Piggin } 1373baa03890SNick Piggin 1374baa03890SNick Piggin /* 137513a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 137613a2c3beSJ. Bruce Fields * unhashed. 1377bad61189SMiklos Szeredi * 1378bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 137944396f4bSJosef Bacik */ 1380bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 138172bd866aSAl Viro unsigned int flags) 138244396f4bSJosef Bacik { 138344396f4bSJosef Bacik struct dentry *old; 138444396f4bSJosef Bacik 138544396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1386bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1387e188dc02SMiklos Szeredi dput(dentry); 138844396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1389e188dc02SMiklos Szeredi } 139044396f4bSJosef Bacik 139172bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 139244396f4bSJosef Bacik if (unlikely(old)) { 139344396f4bSJosef Bacik dput(dentry); 139444396f4bSJosef Bacik dentry = old; 139544396f4bSJosef Bacik } 139644396f4bSJosef Bacik return dentry; 139744396f4bSJosef Bacik } 139844396f4bSJosef Bacik 1399a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 140072bd866aSAl Viro struct dentry *base, unsigned int flags) 1401a3255546SAl Viro { 1402bad61189SMiklos Szeredi bool need_lookup; 1403a3255546SAl Viro struct dentry *dentry; 1404a3255546SAl Viro 140572bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1406bad61189SMiklos Szeredi if (!need_lookup) 1407a3255546SAl Viro return dentry; 1408bad61189SMiklos Szeredi 140972bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1410a3255546SAl Viro } 1411a3255546SAl Viro 141244396f4bSJosef Bacik /* 14131da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14141da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14151da177e4SLinus Torvalds * It _is_ time-critical. 14161da177e4SLinus Torvalds */ 1417e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 141831e6b01fSNick Piggin struct path *path, struct inode **inode) 14191da177e4SLinus Torvalds { 14204ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 142131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14225a18fff2SAl Viro int need_reval = 1; 14235a18fff2SAl Viro int status = 1; 14249875cf80SDavid Howells int err; 14259875cf80SDavid Howells 14263cac260aSAl Viro /* 1427b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1428b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1429b04f784eSNick Piggin * do the non-racy lookup, below. 1430b04f784eSNick Piggin */ 143131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 143231e6b01fSNick Piggin unsigned seq; 1433766c4cbfSAl Viro bool negative; 1434da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14355a18fff2SAl Viro if (!dentry) 14365a18fff2SAl Viro goto unlazy; 14375a18fff2SAl Viro 143812f8ad4bSLinus Torvalds /* 143912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 144012f8ad4bSLinus Torvalds * the dentry name information from lookup. 144112f8ad4bSLinus Torvalds */ 144212f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1443766c4cbfSAl Viro negative = d_is_negative(dentry); 144412f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 144512f8ad4bSLinus Torvalds return -ECHILD; 1446766c4cbfSAl Viro if (negative) 1447766c4cbfSAl Viro return -ENOENT; 144812f8ad4bSLinus Torvalds 144912f8ad4bSLinus Torvalds /* 145012f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 145112f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 145212f8ad4bSLinus Torvalds * 145312f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 145412f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 145512f8ad4bSLinus Torvalds */ 145631e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 145731e6b01fSNick Piggin return -ECHILD; 145831e6b01fSNick Piggin nd->seq = seq; 14595a18fff2SAl Viro 146024643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14614ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14625a18fff2SAl Viro if (unlikely(status <= 0)) { 14635a18fff2SAl Viro if (status != -ECHILD) 14645a18fff2SAl Viro need_reval = 0; 14655a18fff2SAl Viro goto unlazy; 14665a18fff2SAl Viro } 146724643087SAl Viro } 146831e6b01fSNick Piggin path->mnt = mnt; 146931e6b01fSNick Piggin path->dentry = dentry; 1470b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14719875cf80SDavid Howells return 0; 14725a18fff2SAl Viro unlazy: 147319660af7SAl Viro if (unlazy_walk(nd, dentry)) 14745a18fff2SAl Viro return -ECHILD; 14755a18fff2SAl Viro } else { 1476e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 147724643087SAl Viro } 14785a18fff2SAl Viro 147981e6f520SAl Viro if (unlikely(!dentry)) 148081e6f520SAl Viro goto need_lookup; 14815a18fff2SAl Viro 14825a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14834ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14845a18fff2SAl Viro if (unlikely(status <= 0)) { 14855a18fff2SAl Viro if (status < 0) { 14865a18fff2SAl Viro dput(dentry); 14875a18fff2SAl Viro return status; 14885a18fff2SAl Viro } 14895542aa2fSEric W. Biederman d_invalidate(dentry); 14905a18fff2SAl Viro dput(dentry); 149181e6f520SAl Viro goto need_lookup; 14925a18fff2SAl Viro } 1493697f514dSMiklos Szeredi 1494766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1495766c4cbfSAl Viro dput(dentry); 1496766c4cbfSAl Viro return -ENOENT; 1497766c4cbfSAl Viro } 14981da177e4SLinus Torvalds path->mnt = mnt; 14991da177e4SLinus Torvalds path->dentry = dentry; 1500756daf26SNeilBrown err = follow_managed(path, nd); 15018402752eSAl Viro if (likely(!err)) 150231e6b01fSNick Piggin *inode = path->dentry->d_inode; 15038402752eSAl Viro return err; 150481e6f520SAl Viro 150581e6f520SAl Viro need_lookup: 1506697f514dSMiklos Szeredi return 1; 1507697f514dSMiklos Szeredi } 1508697f514dSMiklos Szeredi 1509697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1510cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1511697f514dSMiklos Szeredi { 1512697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1513697f514dSMiklos Szeredi 1514697f514dSMiklos Szeredi parent = nd->path.dentry; 151581e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 151681e6f520SAl Viro 151781e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1518cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 151981e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 152081e6f520SAl Viro if (IS_ERR(dentry)) 152181e6f520SAl Viro return PTR_ERR(dentry); 1522697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1523697f514dSMiklos Szeredi path->dentry = dentry; 15248402752eSAl Viro return follow_managed(path, nd); 15251da177e4SLinus Torvalds } 15261da177e4SLinus Torvalds 152752094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 152852094c8aSAl Viro { 152952094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15304ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 153152094c8aSAl Viro if (err != -ECHILD) 153252094c8aSAl Viro return err; 153319660af7SAl Viro if (unlazy_walk(nd, NULL)) 153452094c8aSAl Viro return -ECHILD; 153552094c8aSAl Viro } 15364ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 153752094c8aSAl Viro } 153852094c8aSAl Viro 15399856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15409856fa1bSAl Viro { 15419856fa1bSAl Viro if (type == LAST_DOTDOT) { 15429856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 154370291aecSAl Viro return follow_dotdot_rcu(nd); 15449856fa1bSAl Viro } else 15459856fa1bSAl Viro follow_dotdot(nd); 15469856fa1bSAl Viro } 15479856fa1bSAl Viro return 0; 15489856fa1bSAl Viro } 15499856fa1bSAl Viro 1550951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1551951361f9SAl Viro { 1552951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1553951361f9SAl Viro path_put(&nd->path); 1554951361f9SAl Viro } else { 1555951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15565b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1557951361f9SAl Viro nd->root.mnt = NULL; 15588b61e74fSAl Viro rcu_read_unlock(); 1559951361f9SAl Viro } 156015439726SAl Viro while (unlikely(nd->depth)) 156115439726SAl Viro put_link(nd); 1562951361f9SAl Viro } 1563951361f9SAl Viro 1564d63ff28fSAl Viro static int pick_link(struct nameidata *nd, struct path *link) 1565d63ff28fSAl Viro { 1566626de996SAl Viro int error; 1567756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1568626de996SAl Viro path_to_nameidata(link, nd); 1569626de996SAl Viro return -ELOOP; 1570626de996SAl Viro } 1571d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1572d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1573d63ff28fSAl Viro unlazy_walk(nd, link->dentry))) { 1574d63ff28fSAl Viro return -ECHILD; 1575d63ff28fSAl Viro } 1576d63ff28fSAl Viro } 1577626de996SAl Viro error = nd_alloc_stack(nd); 1578626de996SAl Viro if (unlikely(error)) { 1579626de996SAl Viro path_to_nameidata(link, nd); 1580626de996SAl Viro return error; 1581626de996SAl Viro } 1582626de996SAl Viro 1583d63ff28fSAl Viro nd->link = *link; 1584d63ff28fSAl Viro return 1; 1585d63ff28fSAl Viro } 1586d63ff28fSAl Viro 15873ddcd056SLinus Torvalds /* 15883ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15893ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15903ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15913ddcd056SLinus Torvalds * for the common case. 15923ddcd056SLinus Torvalds */ 1593d63ff28fSAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow) 15943ddcd056SLinus Torvalds { 1595d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1596d63ff28fSAl Viro return 0; 1597d63ff28fSAl Viro if (!follow) 1598d63ff28fSAl Viro return 0; 1599d63ff28fSAl Viro return pick_link(nd, link); 16003ddcd056SLinus Torvalds } 16013ddcd056SLinus Torvalds 16024693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16034693a547SAl Viro 16044693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1605ce57dfc1SAl Viro { 1606caa85634SAl Viro struct path path; 1607ce57dfc1SAl Viro struct inode *inode; 1608ce57dfc1SAl Viro int err; 1609ce57dfc1SAl Viro /* 1610ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1611ce57dfc1SAl Viro * to be able to know about the current root directory and 1612ce57dfc1SAl Viro * parent relationships. 1613ce57dfc1SAl Viro */ 16144693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16154693a547SAl Viro err = handle_dots(nd, nd->last_type); 16164693a547SAl Viro if (flags & WALK_PUT) 16174693a547SAl Viro put_link(nd); 16184693a547SAl Viro return err; 16194693a547SAl Viro } 1620caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1621ce57dfc1SAl Viro if (unlikely(err)) { 1622697f514dSMiklos Szeredi if (err < 0) 1623f0a9ba70SAl Viro return err; 1624697f514dSMiklos Szeredi 1625caa85634SAl Viro err = lookup_slow(nd, &path); 1626697f514dSMiklos Szeredi if (err < 0) 1627f0a9ba70SAl Viro return err; 1628697f514dSMiklos Szeredi 1629caa85634SAl Viro inode = path.dentry->d_inode; 1630697f514dSMiklos Szeredi err = -ENOENT; 1631caa85634SAl Viro if (d_is_negative(path.dentry)) 1632697f514dSMiklos Szeredi goto out_path_put; 1633766c4cbfSAl Viro } 1634697f514dSMiklos Szeredi 16354693a547SAl Viro if (flags & WALK_PUT) 16364693a547SAl Viro put_link(nd); 1637d63ff28fSAl Viro err = should_follow_link(nd, &path, flags & WALK_GET); 1638d63ff28fSAl Viro if (unlikely(err)) 1639d63ff28fSAl Viro return err; 1640caa85634SAl Viro path_to_nameidata(&path, nd); 1641ce57dfc1SAl Viro nd->inode = inode; 1642ce57dfc1SAl Viro return 0; 1643697f514dSMiklos Szeredi 1644697f514dSMiklos Szeredi out_path_put: 1645caa85634SAl Viro path_to_nameidata(&path, nd); 1646697f514dSMiklos Szeredi return err; 1647ce57dfc1SAl Viro } 1648ce57dfc1SAl Viro 16491da177e4SLinus Torvalds /* 1650bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1651bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1652bfcfaa77SLinus Torvalds * 1653bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1654bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1655bfcfaa77SLinus Torvalds * fast. 1656bfcfaa77SLinus Torvalds * 1657bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1658bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1659bfcfaa77SLinus Torvalds * crossing operation. 1660bfcfaa77SLinus Torvalds * 1661bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1662bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1663bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1664bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1665bfcfaa77SLinus Torvalds */ 1666bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1667bfcfaa77SLinus Torvalds 1668f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1669bfcfaa77SLinus Torvalds 1670f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1671bfcfaa77SLinus Torvalds 1672bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1673bfcfaa77SLinus Torvalds { 167499d263d4SLinus Torvalds return hash_64(hash, 32); 1675bfcfaa77SLinus Torvalds } 1676bfcfaa77SLinus Torvalds 1677bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1678bfcfaa77SLinus Torvalds 1679bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1680bfcfaa77SLinus Torvalds 1681bfcfaa77SLinus Torvalds #endif 1682bfcfaa77SLinus Torvalds 1683bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1684bfcfaa77SLinus Torvalds { 1685bfcfaa77SLinus Torvalds unsigned long a, mask; 1686bfcfaa77SLinus Torvalds unsigned long hash = 0; 1687bfcfaa77SLinus Torvalds 1688bfcfaa77SLinus Torvalds for (;;) { 1689e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1690bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1691bfcfaa77SLinus Torvalds break; 1692bfcfaa77SLinus Torvalds hash += a; 1693f132c5beSAl Viro hash *= 9; 1694bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1695bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1696bfcfaa77SLinus Torvalds if (!len) 1697bfcfaa77SLinus Torvalds goto done; 1698bfcfaa77SLinus Torvalds } 1699a5c21dceSWill Deacon mask = bytemask_from_count(len); 1700bfcfaa77SLinus Torvalds hash += mask & a; 1701bfcfaa77SLinus Torvalds done: 1702bfcfaa77SLinus Torvalds return fold_hash(hash); 1703bfcfaa77SLinus Torvalds } 1704bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1705bfcfaa77SLinus Torvalds 1706bfcfaa77SLinus Torvalds /* 1707bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1708d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1709bfcfaa77SLinus Torvalds */ 1710d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1711bfcfaa77SLinus Torvalds { 171236126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 171336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1714bfcfaa77SLinus Torvalds 1715bfcfaa77SLinus Torvalds hash = a = 0; 1716bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1717bfcfaa77SLinus Torvalds do { 1718bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1719bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1720e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 172136126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 172236126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1723bfcfaa77SLinus Torvalds 172436126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 172536126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172636126f8fSLinus Torvalds 172736126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 172836126f8fSLinus Torvalds 172936126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17309226b5b4SLinus Torvalds len += find_zero(mask); 1731d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1732bfcfaa77SLinus Torvalds } 1733bfcfaa77SLinus Torvalds 1734bfcfaa77SLinus Torvalds #else 1735bfcfaa77SLinus Torvalds 17360145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17370145acc2SLinus Torvalds { 17380145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17390145acc2SLinus Torvalds while (len--) 17400145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17410145acc2SLinus Torvalds return end_name_hash(hash); 17420145acc2SLinus Torvalds } 1743ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17440145acc2SLinus Torvalds 17453ddcd056SLinus Torvalds /* 1746200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1747200e9ef7SLinus Torvalds * one character. 1748200e9ef7SLinus Torvalds */ 1749d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1750200e9ef7SLinus Torvalds { 1751200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1752200e9ef7SLinus Torvalds unsigned long len = 0, c; 1753200e9ef7SLinus Torvalds 1754200e9ef7SLinus Torvalds c = (unsigned char)*name; 1755200e9ef7SLinus Torvalds do { 1756200e9ef7SLinus Torvalds len++; 1757200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1758200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1759200e9ef7SLinus Torvalds } while (c && c != '/'); 1760d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1761200e9ef7SLinus Torvalds } 1762200e9ef7SLinus Torvalds 1763bfcfaa77SLinus Torvalds #endif 1764bfcfaa77SLinus Torvalds 1765200e9ef7SLinus Torvalds /* 17661da177e4SLinus Torvalds * Name resolution. 1767ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1768ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17691da177e4SLinus Torvalds * 1770ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1771ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17721da177e4SLinus Torvalds */ 17736de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17741da177e4SLinus Torvalds { 17751da177e4SLinus Torvalds int err; 17761da177e4SLinus Torvalds 17771da177e4SLinus Torvalds while (*name=='/') 17781da177e4SLinus Torvalds name++; 17791da177e4SLinus Torvalds if (!*name) 17809e18f10aSAl Viro return 0; 17811da177e4SLinus Torvalds 17821da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17831da177e4SLinus Torvalds for(;;) { 1784d6bb3e90SLinus Torvalds u64 hash_len; 1785fe479a58SAl Viro int type; 17861da177e4SLinus Torvalds 178752094c8aSAl Viro err = may_lookup(nd); 17881da177e4SLinus Torvalds if (err) 17891da177e4SLinus Torvalds break; 17901da177e4SLinus Torvalds 1791d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17921da177e4SLinus Torvalds 1793fe479a58SAl Viro type = LAST_NORM; 1794d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1795fe479a58SAl Viro case 2: 1796200e9ef7SLinus Torvalds if (name[1] == '.') { 1797fe479a58SAl Viro type = LAST_DOTDOT; 179816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 179916c2cd71SAl Viro } 1800fe479a58SAl Viro break; 1801fe479a58SAl Viro case 1: 1802fe479a58SAl Viro type = LAST_DOT; 1803fe479a58SAl Viro } 18045a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18055a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18075a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1808a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1809da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18105a202bcdSAl Viro if (err < 0) 18115a202bcdSAl Viro break; 1812d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1813d6bb3e90SLinus Torvalds name = this.name; 18145a202bcdSAl Viro } 18155a202bcdSAl Viro } 1816fe479a58SAl Viro 1817d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1818d6bb3e90SLinus Torvalds nd->last.name = name; 18195f4a6a69SAl Viro nd->last_type = type; 18205f4a6a69SAl Viro 1821d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1822d6bb3e90SLinus Torvalds if (!*name) 1823bdf6cbf1SAl Viro goto OK; 1824200e9ef7SLinus Torvalds /* 1825200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1826200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1827200e9ef7SLinus Torvalds */ 1828200e9ef7SLinus Torvalds do { 1829d6bb3e90SLinus Torvalds name++; 1830d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18318620c238SAl Viro if (unlikely(!*name)) { 18328620c238SAl Viro OK: 18338620c238SAl Viro /* called from path_init(), done */ 18348620c238SAl Viro if (!nd->depth) 18358620c238SAl Viro return 0; 18368620c238SAl Viro name = nd->stack[nd->depth - 1].name; 18378620c238SAl Viro /* called from trailing_symlink(), done */ 18388620c238SAl Viro if (!name) 18398620c238SAl Viro return 0; 18408620c238SAl Viro /* last component of nested symlink */ 18414693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18428620c238SAl Viro } else { 18434693a547SAl Viro err = walk_component(nd, WALK_GET); 18448620c238SAl Viro } 1845ce57dfc1SAl Viro if (err < 0) 1846f0a9ba70SAl Viro break; 1847fe479a58SAl Viro 1848ce57dfc1SAl Viro if (err) { 1849626de996SAl Viro const char *s = get_link(nd); 18505a460275SAl Viro 1851172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1852172a39a0SAl Viro err = PTR_ERR(s); 18531bc4b813SAl Viro break; 1854172a39a0SAl Viro } 1855172a39a0SAl Viro err = 0; 185612b09578SAl Viro if (unlikely(!s)) { 185712b09578SAl Viro /* jumped */ 1858b9ff4429SAl Viro put_link(nd); 185912b09578SAl Viro } else { 1860172a39a0SAl Viro if (*s == '/') { 1861172a39a0SAl Viro if (!nd->root.mnt) 1862172a39a0SAl Viro set_root(nd); 1863172a39a0SAl Viro path_put(&nd->path); 1864172a39a0SAl Viro nd->path = nd->root; 1865172a39a0SAl Viro path_get(&nd->root); 1866172a39a0SAl Viro nd->flags |= LOOKUP_JUMPED; 18679e18f10aSAl Viro while (unlikely(*++s == '/')) 18689e18f10aSAl Viro ; 1869172a39a0SAl Viro } 1870172a39a0SAl Viro nd->inode = nd->path.dentry->d_inode; 1871071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 18729e18f10aSAl Viro if (!*s) 18739e18f10aSAl Viro goto OK; 187432cd7468SAl Viro name = s; 18759e18f10aSAl Viro continue; 187648c8b0c5SAl Viro } 187731e6b01fSNick Piggin } 187844b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18793ddcd056SLinus Torvalds err = -ENOTDIR; 18803ddcd056SLinus Torvalds break; 18815f4a6a69SAl Viro } 1882ce57dfc1SAl Viro } 1883951361f9SAl Viro terminate_walk(nd); 18841da177e4SLinus Torvalds return err; 188507681481SAl Viro } 18861da177e4SLinus Torvalds 18876e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18885e53084dSAl Viro struct nameidata *nd) 188931e6b01fSNick Piggin { 189031e6b01fSNick Piggin int retval = 0; 1891fd2f7cb5SAl Viro const char *s = name->name; 189231e6b01fSNick Piggin 189331e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1894980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 189531e6b01fSNick Piggin nd->depth = 0; 18965e53084dSAl Viro nd->base = NULL; 18975b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1898b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1899b18825a7SDavid Howells struct inode *inode = root->d_inode; 1900fd2f7cb5SAl Viro if (*s) { 190144b1d530SMiklos Szeredi if (!d_can_lookup(root)) 19025b6ca027SAl Viro return -ENOTDIR; 19035b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19045b6ca027SAl Viro if (retval) 19055b6ca027SAl Viro return retval; 190673d049a4SAl Viro } 19075b6ca027SAl Viro nd->path = nd->root; 19085b6ca027SAl Viro nd->inode = inode; 19095b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19108b61e74fSAl Viro rcu_read_lock(); 19115b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 191248a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19135b6ca027SAl Viro } else { 19145b6ca027SAl Viro path_get(&nd->path); 19155b6ca027SAl Viro } 1916d465887fSAl Viro goto done; 19175b6ca027SAl Viro } 19185b6ca027SAl Viro 191931e6b01fSNick Piggin nd->root.mnt = NULL; 192031e6b01fSNick Piggin 192148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1922fd2f7cb5SAl Viro if (*s == '/') { 1923e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19248b61e74fSAl Viro rcu_read_lock(); 19257bd88377SAl Viro nd->seq = set_root_rcu(nd); 1926e41f7d4eSAl Viro } else { 1927e41f7d4eSAl Viro set_root(nd); 1928e41f7d4eSAl Viro path_get(&nd->root); 1929e41f7d4eSAl Viro } 193031e6b01fSNick Piggin nd->path = nd->root; 193131e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1932e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 193331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1934c28cc364SNick Piggin unsigned seq; 193531e6b01fSNick Piggin 19368b61e74fSAl Viro rcu_read_lock(); 193731e6b01fSNick Piggin 1938c28cc364SNick Piggin do { 1939c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 194031e6b01fSNick Piggin nd->path = fs->pwd; 1941c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1942c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1943e41f7d4eSAl Viro } else { 1944e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1945e41f7d4eSAl Viro } 194631e6b01fSNick Piggin } else { 1947582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19482903ff01SAl Viro struct fd f = fdget_raw(dfd); 194931e6b01fSNick Piggin struct dentry *dentry; 195031e6b01fSNick Piggin 19512903ff01SAl Viro if (!f.file) 19522903ff01SAl Viro return -EBADF; 195331e6b01fSNick Piggin 19542903ff01SAl Viro dentry = f.file->f_path.dentry; 195531e6b01fSNick Piggin 1956fd2f7cb5SAl Viro if (*s) { 195744b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19582903ff01SAl Viro fdput(f); 19592903ff01SAl Viro return -ENOTDIR; 1960f52e0c11SAl Viro } 19612903ff01SAl Viro } 19622903ff01SAl Viro 19632903ff01SAl Viro nd->path = f.file->f_path; 1964e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19659c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19665e53084dSAl Viro nd->base = f.file; 1967c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19688b61e74fSAl Viro rcu_read_lock(); 19695590ff0dSUlrich Drepper } else { 19702903ff01SAl Viro path_get(&nd->path); 19712903ff01SAl Viro fdput(f); 19721da177e4SLinus Torvalds } 1973e41f7d4eSAl Viro } 1974e41f7d4eSAl Viro 197531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19764023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1977d465887fSAl Viro goto done; 19784023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1979d465887fSAl Viro goto done; 19804023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19814023bfc9SAl Viro nd->root.mnt = NULL; 19824023bfc9SAl Viro rcu_read_unlock(); 19834023bfc9SAl Viro return -ECHILD; 1984d465887fSAl Viro done: 1985756daf26SNeilBrown nd->total_link_count = 0; 1986dc7af8dcSAl Viro return link_path_walk(s, nd); 19879b4a9b14SAl Viro } 19889b4a9b14SAl Viro 1989893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1990893b7775SAl Viro { 1991893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1992893b7775SAl Viro path_put(&nd->root); 1993893b7775SAl Viro nd->root.mnt = NULL; 1994893b7775SAl Viro } 1995893b7775SAl Viro if (unlikely(nd->base)) 1996893b7775SAl Viro fput(nd->base); 19979b4a9b14SAl Viro } 19989b4a9b14SAl Viro 19991d8e03d3SAl Viro static int trailing_symlink(struct nameidata *nd) 200095fa25d9SAl Viro { 200195fa25d9SAl Viro const char *s; 20021d8e03d3SAl Viro int error = may_follow_link(&nd->link, nd); 200395fa25d9SAl Viro if (unlikely(error)) 200495fa25d9SAl Viro return error; 200595fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 20063b2e7f75SAl Viro s = get_link(nd); 20071bc4b813SAl Viro if (unlikely(IS_ERR(s))) { 20081bc4b813SAl Viro terminate_walk(nd); 200995fa25d9SAl Viro return PTR_ERR(s); 20101bc4b813SAl Viro } 20119ea57b72SAl Viro if (unlikely(!s)) 201295fa25d9SAl Viro return 0; 201395fa25d9SAl Viro if (*s == '/') { 201495fa25d9SAl Viro if (!nd->root.mnt) 201595fa25d9SAl Viro set_root(nd); 201695fa25d9SAl Viro path_put(&nd->path); 201795fa25d9SAl Viro nd->path = nd->root; 201895fa25d9SAl Viro path_get(&nd->root); 201995fa25d9SAl Viro nd->flags |= LOOKUP_JUMPED; 202095fa25d9SAl Viro } 202195fa25d9SAl Viro nd->inode = nd->path.dentry->d_inode; 2022939724dfSAl Viro nd->stack[0].name = NULL; 20238eff733aSAl Viro return link_path_walk(s, nd); 202495fa25d9SAl Viro } 202595fa25d9SAl Viro 2026caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2027bd92d7feSAl Viro { 2028f0a9ba70SAl Viro int err; 2029bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2030bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2031bd92d7feSAl Viro 2032bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 20334693a547SAl Viro err = walk_component(nd, 20344693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20354693a547SAl Viro ? nd->depth 20364693a547SAl Viro ? WALK_PUT | WALK_GET 20374693a547SAl Viro : WALK_GET 20384693a547SAl Viro : 0); 2039f0a9ba70SAl Viro if (err < 0) 2040f0a9ba70SAl Viro terminate_walk(nd); 2041f0a9ba70SAl Viro return err; 2042bd92d7feSAl Viro } 2043bd92d7feSAl Viro 20449b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20455eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20469b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20479b4a9b14SAl Viro { 2048bd92d7feSAl Viro int err; 204931e6b01fSNick Piggin 205031e6b01fSNick Piggin /* 205131e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 205231e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 205331e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 205431e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 205531e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 205631e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 205731e6b01fSNick Piggin * analogue, foo_rcu(). 205831e6b01fSNick Piggin * 205931e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 206031e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 206131e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 206231e6b01fSNick Piggin * be able to complete). 206331e6b01fSNick Piggin */ 20646e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2065bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2066191d7f73SAl Viro while ((err = lookup_last(nd)) > 0) { 20671d8e03d3SAl Viro err = trailing_symlink(nd); 20686d7b5aaeSAl Viro if (err) 20696d7b5aaeSAl Viro break; 2070bd92d7feSAl Viro } 2071bd92d7feSAl Viro } 2072ee0827cdSAl Viro 20739f1fafeeSAl Viro if (!err) 20749f1fafeeSAl Viro err = complete_walk(nd); 2075bd92d7feSAl Viro 2076bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 207744b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2078bd92d7feSAl Viro path_put(&nd->path); 2079bd23a539SAl Viro err = -ENOTDIR; 2080bd92d7feSAl Viro } 2081bd92d7feSAl Viro } 208216c2cd71SAl Viro 2083893b7775SAl Viro path_cleanup(nd); 2084bd92d7feSAl Viro return err; 208531e6b01fSNick Piggin } 208631e6b01fSNick Piggin 2087873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2088873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2089873f1eedSJeff Layton { 2090894bc8c4SAl Viro int retval; 2091756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2092894bc8c4SAl Viro 2093894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2094873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20955eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2096873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20975eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2098873f1eedSJeff Layton 2099873f1eedSJeff Layton if (likely(!retval)) 2100adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2101756daf26SNeilBrown restore_nameidata(saved_nd); 2102873f1eedSJeff Layton return retval; 2103873f1eedSJeff Layton } 2104873f1eedSJeff Layton 210579714f72SAl Viro /* does lookup, returns the object with parent locked */ 210679714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21075590ff0dSUlrich Drepper { 210851689104SPaul Moore struct filename *filename = getname_kernel(name); 210979714f72SAl Viro struct nameidata nd; 211079714f72SAl Viro struct dentry *d; 211151689104SPaul Moore int err; 211251689104SPaul Moore 211351689104SPaul Moore if (IS_ERR(filename)) 211451689104SPaul Moore return ERR_CAST(filename); 211551689104SPaul Moore 211651689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 211751689104SPaul Moore if (err) { 211851689104SPaul Moore d = ERR_PTR(err); 211951689104SPaul Moore goto out; 212051689104SPaul Moore } 212179714f72SAl Viro if (nd.last_type != LAST_NORM) { 212279714f72SAl Viro path_put(&nd.path); 212351689104SPaul Moore d = ERR_PTR(-EINVAL); 212451689104SPaul Moore goto out; 212579714f72SAl Viro } 212679714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21271e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 212879714f72SAl Viro if (IS_ERR(d)) { 212979714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 213079714f72SAl Viro path_put(&nd.path); 213151689104SPaul Moore goto out; 213279714f72SAl Viro } 213379714f72SAl Viro *path = nd.path; 213451689104SPaul Moore out: 213551689104SPaul Moore putname(filename); 213679714f72SAl Viro return d; 21375590ff0dSUlrich Drepper } 21385590ff0dSUlrich Drepper 2139d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2140d1811465SAl Viro { 2141d1811465SAl Viro struct nameidata nd; 214274eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 214374eb8cc5SAl Viro int res = PTR_ERR(filename); 214474eb8cc5SAl Viro 214574eb8cc5SAl Viro if (!IS_ERR(filename)) { 214674eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 214774eb8cc5SAl Viro putname(filename); 2148d1811465SAl Viro if (!res) 2149d1811465SAl Viro *path = nd.path; 215074eb8cc5SAl Viro } 2151d1811465SAl Viro return res; 2152d1811465SAl Viro } 21534d359507SAl Viro EXPORT_SYMBOL(kern_path); 2154d1811465SAl Viro 215516f18200SJosef 'Jeff' Sipek /** 215616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 215716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 215816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 215916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 216016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2161e0a01249SAl Viro * @path: pointer to struct path to fill 216216f18200SJosef 'Jeff' Sipek */ 216316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 216416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2165e0a01249SAl Viro struct path *path) 216616f18200SJosef 'Jeff' Sipek { 216774eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 216874eb8cc5SAl Viro int err = PTR_ERR(filename); 216974eb8cc5SAl Viro 217074eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 217174eb8cc5SAl Viro 217274eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 217374eb8cc5SAl Viro if (!IS_ERR(filename)) { 2174e0a01249SAl Viro struct nameidata nd; 2175e0a01249SAl Viro nd.root.dentry = dentry; 2176e0a01249SAl Viro nd.root.mnt = mnt; 217774eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 217874eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2179e0a01249SAl Viro if (!err) 2180e0a01249SAl Viro *path = nd.path; 218174eb8cc5SAl Viro putname(filename); 218274eb8cc5SAl Viro } 2183e0a01249SAl Viro return err; 218416f18200SJosef 'Jeff' Sipek } 21854d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 218616f18200SJosef 'Jeff' Sipek 2187eead1911SChristoph Hellwig /** 2188a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2189eead1911SChristoph Hellwig * @name: pathname component to lookup 2190eead1911SChristoph Hellwig * @base: base directory to lookup from 2191eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2192eead1911SChristoph Hellwig * 2193a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21949e7543e9SAl Viro * not be called by generic code. 2195eead1911SChristoph Hellwig */ 2196057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2197057f6c01SJames Morris { 2198057f6c01SJames Morris struct qstr this; 21996a96ba54SAl Viro unsigned int c; 2200cda309deSMiklos Szeredi int err; 2201057f6c01SJames Morris 22022f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22032f9092e1SDavid Woodhouse 22046a96ba54SAl Viro this.name = name; 22056a96ba54SAl Viro this.len = len; 22060145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22076a96ba54SAl Viro if (!len) 22086a96ba54SAl Viro return ERR_PTR(-EACCES); 22096a96ba54SAl Viro 221021d8a15aSAl Viro if (unlikely(name[0] == '.')) { 221121d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 221221d8a15aSAl Viro return ERR_PTR(-EACCES); 221321d8a15aSAl Viro } 221421d8a15aSAl Viro 22156a96ba54SAl Viro while (len--) { 22166a96ba54SAl Viro c = *(const unsigned char *)name++; 22176a96ba54SAl Viro if (c == '/' || c == '\0') 22186a96ba54SAl Viro return ERR_PTR(-EACCES); 22196a96ba54SAl Viro } 22205a202bcdSAl Viro /* 22215a202bcdSAl Viro * See if the low-level filesystem might want 22225a202bcdSAl Viro * to use its own hash.. 22235a202bcdSAl Viro */ 22245a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2225da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22265a202bcdSAl Viro if (err < 0) 22275a202bcdSAl Viro return ERR_PTR(err); 22285a202bcdSAl Viro } 2229eead1911SChristoph Hellwig 2230cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2231cda309deSMiklos Szeredi if (err) 2232cda309deSMiklos Szeredi return ERR_PTR(err); 2233cda309deSMiklos Szeredi 223472bd866aSAl Viro return __lookup_hash(&this, base, 0); 2235057f6c01SJames Morris } 22364d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2237057f6c01SJames Morris 22381fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22391fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22401da177e4SLinus Torvalds { 22412d8f3038SAl Viro struct nameidata nd; 224291a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22431da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22441da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22452d8f3038SAl Viro 22462d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22472d8f3038SAl Viro 2248873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22491da177e4SLinus Torvalds putname(tmp); 22502d8f3038SAl Viro if (!err) 22512d8f3038SAl Viro *path = nd.path; 22521da177e4SLinus Torvalds } 22531da177e4SLinus Torvalds return err; 22541da177e4SLinus Torvalds } 22551da177e4SLinus Torvalds 22561fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22571fa1e7f6SAndy Whitcroft struct path *path) 22581fa1e7f6SAndy Whitcroft { 2259f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22601fa1e7f6SAndy Whitcroft } 22614d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22621fa1e7f6SAndy Whitcroft 2263873f1eedSJeff Layton /* 2264873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2265873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2266873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2267873f1eedSJeff Layton * path-walking is complete. 2268873f1eedSJeff Layton */ 226991a27b2aSJeff Layton static struct filename * 2270f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2271f5beed75SAl Viro struct path *parent, 2272f5beed75SAl Viro struct qstr *last, 2273f5beed75SAl Viro int *type, 22749e790bd6SJeff Layton unsigned int flags) 22752ad94ae6SAl Viro { 2276f5beed75SAl Viro struct nameidata nd; 227791a27b2aSJeff Layton struct filename *s = getname(path); 22782ad94ae6SAl Viro int error; 22792ad94ae6SAl Viro 22809e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22819e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22829e790bd6SJeff Layton 22832ad94ae6SAl Viro if (IS_ERR(s)) 228491a27b2aSJeff Layton return s; 22852ad94ae6SAl Viro 2286f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 228791a27b2aSJeff Layton if (error) { 22882ad94ae6SAl Viro putname(s); 228991a27b2aSJeff Layton return ERR_PTR(error); 229091a27b2aSJeff Layton } 2291f5beed75SAl Viro *parent = nd.path; 2292f5beed75SAl Viro *last = nd.last; 2293f5beed75SAl Viro *type = nd.last_type; 22942ad94ae6SAl Viro 229591a27b2aSJeff Layton return s; 22962ad94ae6SAl Viro } 22972ad94ae6SAl Viro 22988033426eSJeff Layton /** 2299197df04cSAl Viro * mountpoint_last - look up last component for umount 23008033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23018033426eSJeff Layton * @path: pointer to container for result 23028033426eSJeff Layton * 23038033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23048033426eSJeff Layton * need to resolve the path without doing any revalidation. 23058033426eSJeff Layton * 23068033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23078033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23088033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23098033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23108033426eSJeff Layton * bogus and it doesn't exist. 23118033426eSJeff Layton * 23128033426eSJeff Layton * Returns: 23138033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23148033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23158033426eSJeff Layton * put in this case. 23168033426eSJeff Layton * 23178033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23188033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23198033426eSJeff Layton * The nd->path reference will also be put. 23208033426eSJeff Layton * 23218033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23228033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23238033426eSJeff Layton * to the link, and nd->path will *not* be put. 23248033426eSJeff Layton */ 23258033426eSJeff Layton static int 2326197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23278033426eSJeff Layton { 23288033426eSJeff Layton int error = 0; 23298033426eSJeff Layton struct dentry *dentry; 23308033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23318033426eSJeff Layton 233235759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 233335759521SAl Viro if (nd->flags & LOOKUP_RCU) { 233435759521SAl Viro if (unlazy_walk(nd, NULL)) { 23358033426eSJeff Layton error = -ECHILD; 233635759521SAl Viro goto out; 233735759521SAl Viro } 23388033426eSJeff Layton } 23398033426eSJeff Layton 23408033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23418033426eSJeff Layton 23428033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23438033426eSJeff Layton error = handle_dots(nd, nd->last_type); 234435759521SAl Viro if (error) 234535759521SAl Viro goto out; 23468033426eSJeff Layton dentry = dget(nd->path.dentry); 234735759521SAl Viro goto done; 23488033426eSJeff Layton } 23498033426eSJeff Layton 23508033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23518033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23528033426eSJeff Layton if (!dentry) { 23538033426eSJeff Layton /* 23548033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23558033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23568033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23578033426eSJeff Layton */ 23588033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23598033426eSJeff Layton if (!dentry) { 23608033426eSJeff Layton error = -ENOMEM; 2361bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236235759521SAl Viro goto out; 23638033426eSJeff Layton } 236435759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 236535759521SAl Viro error = PTR_ERR(dentry); 2366bcceeebaSDave Jones if (IS_ERR(dentry)) { 2367bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236835759521SAl Viro goto out; 23698033426eSJeff Layton } 2370bcceeebaSDave Jones } 23718033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23728033426eSJeff Layton 237335759521SAl Viro done: 2374698934dfSDavid Howells if (d_is_negative(dentry)) { 23758033426eSJeff Layton error = -ENOENT; 23768033426eSJeff Layton dput(dentry); 237735759521SAl Viro goto out; 237835759521SAl Viro } 2379191d7f73SAl Viro if (nd->depth) 2380191d7f73SAl Viro put_link(nd); 23818033426eSJeff Layton path->dentry = dentry; 2382295dc39dSVasily Averin path->mnt = nd->path.mnt; 2383d63ff28fSAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW); 2384d63ff28fSAl Viro if (unlikely(error)) { 2385d63ff28fSAl Viro if (error < 0) 2386d63ff28fSAl Viro goto out; 2387d63ff28fSAl Viro return error; 2388caa85634SAl Viro } 2389295dc39dSVasily Averin mntget(path->mnt); 23908033426eSJeff Layton follow_mount(path); 239135759521SAl Viro error = 0; 239235759521SAl Viro out: 23938033426eSJeff Layton terminate_walk(nd); 23948033426eSJeff Layton return error; 23958033426eSJeff Layton } 23968033426eSJeff Layton 23978033426eSJeff Layton /** 2398197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23998033426eSJeff Layton * @dfd: directory file descriptor to start walk from 24008033426eSJeff Layton * @name: full pathname to walk 2401606d6fe3SRandy Dunlap * @path: pointer to container for result 24028033426eSJeff Layton * @flags: lookup flags 24038033426eSJeff Layton * 24048033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2405606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24068033426eSJeff Layton */ 24078033426eSJeff Layton static int 2408668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 240946afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24108033426eSJeff Layton { 241146afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 24128033426eSJeff Layton if (unlikely(err)) 2413115cbfdcSAl Viro goto out; 24148033426eSJeff Layton 2415191d7f73SAl Viro while ((err = mountpoint_last(nd, path)) > 0) { 24161d8e03d3SAl Viro err = trailing_symlink(nd); 24178033426eSJeff Layton if (err) 24188033426eSJeff Layton break; 24198033426eSJeff Layton } 24208033426eSJeff Layton out: 242146afd6f6SAl Viro path_cleanup(nd); 24228033426eSJeff Layton return err; 24238033426eSJeff Layton } 24248033426eSJeff Layton 24252d864651SAl Viro static int 2426668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24272d864651SAl Viro unsigned int flags) 24282d864651SAl Viro { 2429756daf26SNeilBrown struct nameidata nd, *saved; 2430cbaab2dbSAl Viro int error; 2431668696dcSAl Viro if (IS_ERR(name)) 2432668696dcSAl Viro return PTR_ERR(name); 2433756daf26SNeilBrown saved = set_nameidata(&nd); 243446afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24352d864651SAl Viro if (unlikely(error == -ECHILD)) 243646afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24372d864651SAl Viro if (unlikely(error == -ESTALE)) 243846afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24392d864651SAl Viro if (likely(!error)) 2440668696dcSAl Viro audit_inode(name, path->dentry, 0); 2441756daf26SNeilBrown restore_nameidata(saved); 2442668696dcSAl Viro putname(name); 24432d864651SAl Viro return error; 24442d864651SAl Viro } 24452d864651SAl Viro 24468033426eSJeff Layton /** 2447197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24488033426eSJeff Layton * @dfd: directory file descriptor 24498033426eSJeff Layton * @name: pathname from userland 24508033426eSJeff Layton * @flags: lookup flags 24518033426eSJeff Layton * @path: pointer to container to hold result 24528033426eSJeff Layton * 24538033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24548033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24558033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24568033426eSJeff Layton * and avoid revalidating the last component. 24578033426eSJeff Layton * 24588033426eSJeff Layton * Returns 0 and populates "path" on success. 24598033426eSJeff Layton */ 24608033426eSJeff Layton int 2461197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24628033426eSJeff Layton struct path *path) 24638033426eSJeff Layton { 2464cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24658033426eSJeff Layton } 24668033426eSJeff Layton 24672d864651SAl Viro int 24682d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24692d864651SAl Viro unsigned int flags) 24702d864651SAl Viro { 2471cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24722d864651SAl Viro } 24732d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24742d864651SAl Viro 2475cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24761da177e4SLinus Torvalds { 24778e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2478da9592edSDavid Howells 24798e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24801da177e4SLinus Torvalds return 0; 24818e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24821da177e4SLinus Torvalds return 0; 248323adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24841da177e4SLinus Torvalds } 2485cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24861da177e4SLinus Torvalds 24871da177e4SLinus Torvalds /* 24881da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24891da177e4SLinus Torvalds * whether the type of victim is right. 24901da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24911da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24921da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24931da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24941da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24951da177e4SLinus Torvalds * a. be owner of dir, or 24961da177e4SLinus Torvalds * b. be owner of victim, or 24971da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24981da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24991da177e4SLinus Torvalds * links pointing to it. 25001da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25011da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25021da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25031da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25041da177e4SLinus Torvalds * nfs_async_unlink(). 25051da177e4SLinus Torvalds */ 2506b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25071da177e4SLinus Torvalds { 2508b18825a7SDavid Howells struct inode *inode = victim->d_inode; 25091da177e4SLinus Torvalds int error; 25101da177e4SLinus Torvalds 2511b18825a7SDavid Howells if (d_is_negative(victim)) 25121da177e4SLinus Torvalds return -ENOENT; 2513b18825a7SDavid Howells BUG_ON(!inode); 25141da177e4SLinus Torvalds 25151da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25164fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25171da177e4SLinus Torvalds 2518f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25191da177e4SLinus Torvalds if (error) 25201da177e4SLinus Torvalds return error; 25211da177e4SLinus Torvalds if (IS_APPEND(dir)) 25221da177e4SLinus Torvalds return -EPERM; 2523b18825a7SDavid Howells 2524b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2525b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25261da177e4SLinus Torvalds return -EPERM; 25271da177e4SLinus Torvalds if (isdir) { 252844b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25291da177e4SLinus Torvalds return -ENOTDIR; 25301da177e4SLinus Torvalds if (IS_ROOT(victim)) 25311da177e4SLinus Torvalds return -EBUSY; 253244b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25331da177e4SLinus Torvalds return -EISDIR; 25341da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25351da177e4SLinus Torvalds return -ENOENT; 25361da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25371da177e4SLinus Torvalds return -EBUSY; 25381da177e4SLinus Torvalds return 0; 25391da177e4SLinus Torvalds } 25401da177e4SLinus Torvalds 25411da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25421da177e4SLinus Torvalds * dir. 25431da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25441da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25451da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25461da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25471da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25481da177e4SLinus Torvalds */ 2549a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25501da177e4SLinus Torvalds { 255114e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25521da177e4SLinus Torvalds if (child->d_inode) 25531da177e4SLinus Torvalds return -EEXIST; 25541da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25551da177e4SLinus Torvalds return -ENOENT; 2556f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25571da177e4SLinus Torvalds } 25581da177e4SLinus Torvalds 25591da177e4SLinus Torvalds /* 25601da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25611da177e4SLinus Torvalds */ 25621da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25631da177e4SLinus Torvalds { 25641da177e4SLinus Torvalds struct dentry *p; 25651da177e4SLinus Torvalds 25661da177e4SLinus Torvalds if (p1 == p2) { 2567f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25681da177e4SLinus Torvalds return NULL; 25691da177e4SLinus Torvalds } 25701da177e4SLinus Torvalds 2571a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25721da177e4SLinus Torvalds 2573e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2574e2761a11SOGAWA Hirofumi if (p) { 2575f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2576f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25771da177e4SLinus Torvalds return p; 25781da177e4SLinus Torvalds } 25791da177e4SLinus Torvalds 2580e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2581e2761a11SOGAWA Hirofumi if (p) { 2582f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2583f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25841da177e4SLinus Torvalds return p; 25851da177e4SLinus Torvalds } 25861da177e4SLinus Torvalds 2587f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2588d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25891da177e4SLinus Torvalds return NULL; 25901da177e4SLinus Torvalds } 25914d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25921da177e4SLinus Torvalds 25931da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25941da177e4SLinus Torvalds { 25951b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25961da177e4SLinus Torvalds if (p1 != p2) { 25971b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2598a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25991da177e4SLinus Torvalds } 26001da177e4SLinus Torvalds } 26014d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26021da177e4SLinus Torvalds 26034acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2604312b63fbSAl Viro bool want_excl) 26051da177e4SLinus Torvalds { 2606a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26071da177e4SLinus Torvalds if (error) 26081da177e4SLinus Torvalds return error; 26091da177e4SLinus Torvalds 2610acfa4380SAl Viro if (!dir->i_op->create) 26111da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26121da177e4SLinus Torvalds mode &= S_IALLUGO; 26131da177e4SLinus Torvalds mode |= S_IFREG; 26141da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26151da177e4SLinus Torvalds if (error) 26161da177e4SLinus Torvalds return error; 2617312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2618a74574aaSStephen Smalley if (!error) 2619f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26201da177e4SLinus Torvalds return error; 26211da177e4SLinus Torvalds } 26224d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26231da177e4SLinus Torvalds 262473d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26251da177e4SLinus Torvalds { 26263fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26271da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26281da177e4SLinus Torvalds int error; 26291da177e4SLinus Torvalds 2630bcda7652SAl Viro /* O_PATH? */ 2631bcda7652SAl Viro if (!acc_mode) 2632bcda7652SAl Viro return 0; 2633bcda7652SAl Viro 26341da177e4SLinus Torvalds if (!inode) 26351da177e4SLinus Torvalds return -ENOENT; 26361da177e4SLinus Torvalds 2637c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2638c8fe8f30SChristoph Hellwig case S_IFLNK: 26391da177e4SLinus Torvalds return -ELOOP; 2640c8fe8f30SChristoph Hellwig case S_IFDIR: 2641c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26421da177e4SLinus Torvalds return -EISDIR; 2643c8fe8f30SChristoph Hellwig break; 2644c8fe8f30SChristoph Hellwig case S_IFBLK: 2645c8fe8f30SChristoph Hellwig case S_IFCHR: 26463fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26471da177e4SLinus Torvalds return -EACCES; 2648c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2649c8fe8f30SChristoph Hellwig case S_IFIFO: 2650c8fe8f30SChristoph Hellwig case S_IFSOCK: 26511da177e4SLinus Torvalds flag &= ~O_TRUNC; 2652c8fe8f30SChristoph Hellwig break; 26534a3fd211SDave Hansen } 2654b41572e9SDave Hansen 26553fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2656b41572e9SDave Hansen if (error) 2657b41572e9SDave Hansen return error; 26586146f0d5SMimi Zohar 26591da177e4SLinus Torvalds /* 26601da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26611da177e4SLinus Torvalds */ 26621da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26638737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26647715b521SAl Viro return -EPERM; 26651da177e4SLinus Torvalds if (flag & O_TRUNC) 26667715b521SAl Viro return -EPERM; 26671da177e4SLinus Torvalds } 26681da177e4SLinus Torvalds 26691da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26702e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26717715b521SAl Viro return -EPERM; 26721da177e4SLinus Torvalds 2673f3c7691eSJ. Bruce Fields return 0; 26747715b521SAl Viro } 26757715b521SAl Viro 2676e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26777715b521SAl Viro { 2678e1181ee6SJeff Layton struct path *path = &filp->f_path; 26797715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26807715b521SAl Viro int error = get_write_access(inode); 26811da177e4SLinus Torvalds if (error) 26827715b521SAl Viro return error; 26831da177e4SLinus Torvalds /* 26841da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26851da177e4SLinus Torvalds */ 2686d7a06983SJeff Layton error = locks_verify_locked(filp); 2687be6d3e56SKentaro Takeda if (!error) 2688ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26891da177e4SLinus Torvalds if (!error) { 26907715b521SAl Viro error = do_truncate(path->dentry, 0, 2691d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2692e1181ee6SJeff Layton filp); 26931da177e4SLinus Torvalds } 26941da177e4SLinus Torvalds put_write_access(inode); 2695acd0c935SMimi Zohar return error; 26961da177e4SLinus Torvalds } 26971da177e4SLinus Torvalds 2698d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2699d57999e1SDave Hansen { 27008a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27018a5e929dSAl Viro flag--; 2702d57999e1SDave Hansen return flag; 2703d57999e1SDave Hansen } 2704d57999e1SDave Hansen 2705d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2706d18e9008SMiklos Szeredi { 2707d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2708d18e9008SMiklos Szeredi if (error) 2709d18e9008SMiklos Szeredi return error; 2710d18e9008SMiklos Szeredi 2711d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2712d18e9008SMiklos Szeredi if (error) 2713d18e9008SMiklos Szeredi return error; 2714d18e9008SMiklos Szeredi 2715d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2716d18e9008SMiklos Szeredi } 2717d18e9008SMiklos Szeredi 27181acf0af9SDavid Howells /* 27191acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27201acf0af9SDavid Howells * dentry. 27211acf0af9SDavid Howells * 27221acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27231acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27241acf0af9SDavid Howells * 27251acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27261acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27271acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27281acf0af9SDavid Howells * 27291acf0af9SDavid Howells * Returns an error code otherwise. 27301acf0af9SDavid Howells */ 27312675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 273230d90494SAl Viro struct path *path, struct file *file, 2733015c3bbcSMiklos Szeredi const struct open_flags *op, 273464894cf8SAl Viro bool got_write, bool need_lookup, 273547237687SAl Viro int *opened) 2736d18e9008SMiklos Szeredi { 2737d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2738d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2739d18e9008SMiklos Szeredi umode_t mode; 2740d18e9008SMiklos Szeredi int error; 2741d18e9008SMiklos Szeredi int acc_mode; 2742d18e9008SMiklos Szeredi int create_error = 0; 2743d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2744116cc022SMiklos Szeredi bool excl; 2745d18e9008SMiklos Szeredi 2746d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2747d18e9008SMiklos Szeredi 2748d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2749d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27502675a4ebSAl Viro error = -ENOENT; 2751d18e9008SMiklos Szeredi goto out; 2752d18e9008SMiklos Szeredi } 2753d18e9008SMiklos Szeredi 275462b259d8SMiklos Szeredi mode = op->mode; 2755d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2756d18e9008SMiklos Szeredi mode &= ~current_umask(); 2757d18e9008SMiklos Szeredi 2758116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2759116cc022SMiklos Szeredi if (excl) 2760d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2761d18e9008SMiklos Szeredi 2762d18e9008SMiklos Szeredi /* 2763d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2764d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2765d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2766d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2767d18e9008SMiklos Szeredi * 2768d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2769d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2770d18e9008SMiklos Szeredi */ 277164894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 277264894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 277364894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2774d18e9008SMiklos Szeredi /* 2775d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2776d18e9008SMiklos Szeredi * back to lookup + open 2777d18e9008SMiklos Szeredi */ 2778d18e9008SMiklos Szeredi goto no_open; 2779d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2780d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 278164894cf8SAl Viro create_error = -EROFS; 2782d18e9008SMiklos Szeredi goto no_open; 2783d18e9008SMiklos Szeredi } else { 2784d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 278564894cf8SAl Viro create_error = -EROFS; 2786d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2787d18e9008SMiklos Szeredi } 2788d18e9008SMiklos Szeredi } 2789d18e9008SMiklos Szeredi 2790d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 279138227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2792d18e9008SMiklos Szeredi if (error) { 2793d18e9008SMiklos Szeredi create_error = error; 2794d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2795d18e9008SMiklos Szeredi goto no_open; 2796d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2797d18e9008SMiklos Szeredi } 2798d18e9008SMiklos Szeredi } 2799d18e9008SMiklos Szeredi 2800d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2801d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2802d18e9008SMiklos Szeredi 280330d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 280430d90494SAl Viro file->f_path.mnt = nd->path.mnt; 280530d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 280647237687SAl Viro opened); 2807d9585277SAl Viro if (error < 0) { 2808d9585277SAl Viro if (create_error && error == -ENOENT) 2809d9585277SAl Viro error = create_error; 2810d18e9008SMiklos Szeredi goto out; 2811d18e9008SMiklos Szeredi } 2812d18e9008SMiklos Szeredi 2813d9585277SAl Viro if (error) { /* returned 1, that is */ 281430d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28152675a4ebSAl Viro error = -EIO; 2816d18e9008SMiklos Szeredi goto out; 2817d18e9008SMiklos Szeredi } 281830d90494SAl Viro if (file->f_path.dentry) { 2819d18e9008SMiklos Szeredi dput(dentry); 282030d90494SAl Viro dentry = file->f_path.dentry; 2821d18e9008SMiklos Szeredi } 282203da633aSAl Viro if (*opened & FILE_CREATED) 282303da633aSAl Viro fsnotify_create(dir, dentry); 282403da633aSAl Viro if (!dentry->d_inode) { 282503da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 282603da633aSAl Viro if (create_error) { 282762b2ce96SSage Weil error = create_error; 282862b2ce96SSage Weil goto out; 282962b2ce96SSage Weil } 283003da633aSAl Viro } else { 283103da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 283203da633aSAl Viro error = -EEXIST; 283303da633aSAl Viro goto out; 283403da633aSAl Viro } 283503da633aSAl Viro } 2836d18e9008SMiklos Szeredi goto looked_up; 2837d18e9008SMiklos Szeredi } 2838d18e9008SMiklos Szeredi 2839d18e9008SMiklos Szeredi /* 2840d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2841d18e9008SMiklos Szeredi * here. 2842d18e9008SMiklos Szeredi */ 284303da633aSAl Viro acc_mode = op->acc_mode; 284403da633aSAl Viro if (*opened & FILE_CREATED) { 284503da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 284603da633aSAl Viro fsnotify_create(dir, dentry); 284703da633aSAl Viro acc_mode = MAY_OPEN; 284803da633aSAl Viro } 28492675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28502675a4ebSAl Viro if (error) 28512675a4ebSAl Viro fput(file); 2852d18e9008SMiklos Szeredi 2853d18e9008SMiklos Szeredi out: 2854d18e9008SMiklos Szeredi dput(dentry); 28552675a4ebSAl Viro return error; 2856d18e9008SMiklos Szeredi 2857d18e9008SMiklos Szeredi no_open: 2858d18e9008SMiklos Szeredi if (need_lookup) { 285972bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2860d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28612675a4ebSAl Viro return PTR_ERR(dentry); 2862d18e9008SMiklos Szeredi 2863d18e9008SMiklos Szeredi if (create_error) { 2864d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2865d18e9008SMiklos Szeredi 28662675a4ebSAl Viro error = create_error; 2867d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2868d18e9008SMiklos Szeredi if (!dentry->d_inode) 2869d18e9008SMiklos Szeredi goto out; 2870d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2871d18e9008SMiklos Szeredi goto out; 2872d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2873e36cb0b8SDavid Howells d_is_reg(dentry)) { 2874d18e9008SMiklos Szeredi goto out; 2875d18e9008SMiklos Szeredi } 2876d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2877d18e9008SMiklos Szeredi } 2878d18e9008SMiklos Szeredi } 2879d18e9008SMiklos Szeredi looked_up: 2880d18e9008SMiklos Szeredi path->dentry = dentry; 2881d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28822675a4ebSAl Viro return 1; 2883d18e9008SMiklos Szeredi } 2884d18e9008SMiklos Szeredi 288531e6b01fSNick Piggin /* 28861acf0af9SDavid Howells * Look up and maybe create and open the last component. 2887d58ffd35SMiklos Szeredi * 2888d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2889d58ffd35SMiklos Szeredi * 28901acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28911acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28921acf0af9SDavid Howells * 28931acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28941acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28951acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28961acf0af9SDavid Howells * specified then a negative dentry may be returned. 28971acf0af9SDavid Howells * 28981acf0af9SDavid Howells * An error code is returned otherwise. 28991acf0af9SDavid Howells * 29001acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29011acf0af9SDavid Howells * cleared otherwise prior to returning. 2902d58ffd35SMiklos Szeredi */ 29032675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 290430d90494SAl Viro struct file *file, 2905d58ffd35SMiklos Szeredi const struct open_flags *op, 290664894cf8SAl Viro bool got_write, int *opened) 2907d58ffd35SMiklos Szeredi { 2908d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 290954ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2910d58ffd35SMiklos Szeredi struct dentry *dentry; 2911d58ffd35SMiklos Szeredi int error; 291254ef4872SMiklos Szeredi bool need_lookup; 2913d58ffd35SMiklos Szeredi 291447237687SAl Viro *opened &= ~FILE_CREATED; 2915201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2916d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29172675a4ebSAl Viro return PTR_ERR(dentry); 2918d58ffd35SMiklos Szeredi 2919d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2920d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2921d18e9008SMiklos Szeredi goto out_no_open; 2922d18e9008SMiklos Szeredi 2923d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 292464894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 292547237687SAl Viro need_lookup, opened); 2926d18e9008SMiklos Szeredi } 2927d18e9008SMiklos Szeredi 292854ef4872SMiklos Szeredi if (need_lookup) { 292954ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 293054ef4872SMiklos Szeredi 293172bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 293254ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29332675a4ebSAl Viro return PTR_ERR(dentry); 293454ef4872SMiklos Szeredi } 293554ef4872SMiklos Szeredi 2936d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2937d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2938d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2939d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2940d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2941d58ffd35SMiklos Szeredi /* 2942d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2943d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2944d58ffd35SMiklos Szeredi * the time when the file is created and when 2945d58ffd35SMiklos Szeredi * a permanent write count is taken through 2946015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2947d58ffd35SMiklos Szeredi */ 294864894cf8SAl Viro if (!got_write) { 294964894cf8SAl Viro error = -EROFS; 2950d58ffd35SMiklos Szeredi goto out_dput; 295164894cf8SAl Viro } 295247237687SAl Viro *opened |= FILE_CREATED; 2953d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2954d58ffd35SMiklos Szeredi if (error) 2955d58ffd35SMiklos Szeredi goto out_dput; 2956312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2957312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2958d58ffd35SMiklos Szeredi if (error) 2959d58ffd35SMiklos Szeredi goto out_dput; 2960d58ffd35SMiklos Szeredi } 2961d18e9008SMiklos Szeredi out_no_open: 2962d58ffd35SMiklos Szeredi path->dentry = dentry; 2963d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29642675a4ebSAl Viro return 1; 2965d58ffd35SMiklos Szeredi 2966d58ffd35SMiklos Szeredi out_dput: 2967d58ffd35SMiklos Szeredi dput(dentry); 29682675a4ebSAl Viro return error; 2969d58ffd35SMiklos Szeredi } 2970d58ffd35SMiklos Szeredi 2971d58ffd35SMiklos Szeredi /* 2972fe2d35ffSAl Viro * Handle the last step of open() 297331e6b01fSNick Piggin */ 2974896475d5SAl Viro static int do_last(struct nameidata *nd, 297530d90494SAl Viro struct file *file, const struct open_flags *op, 2976669abf4eSJeff Layton int *opened, struct filename *name) 2977fb1cc555SAl Viro { 2978a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2979ca344a89SAl Viro int open_flag = op->open_flag; 298077d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 298164894cf8SAl Viro bool got_write = false; 2982bcda7652SAl Viro int acc_mode = op->acc_mode; 2983a1eb3315SMiklos Szeredi struct inode *inode; 298416b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2985896475d5SAl Viro struct path path; 298616b1c1cdSMiklos Szeredi bool retried = false; 298716c2cd71SAl Viro int error; 2988fb1cc555SAl Viro 2989c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2990c3e380b0SAl Viro nd->flags |= op->intent; 2991c3e380b0SAl Viro 2992bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2993fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 299470291aecSAl Viro if (unlikely(error)) { 299570291aecSAl Viro terminate_walk(nd); 29962675a4ebSAl Viro return error; 299770291aecSAl Viro } 2998e83db167SMiklos Szeredi goto finish_open; 29991f36f774SAl Viro } 3000a2c36b45SAl Viro 3001ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3002fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3003fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3004fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3005896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 300671574865SMiklos Szeredi if (likely(!error)) 300771574865SMiklos Szeredi goto finish_lookup; 300871574865SMiklos Szeredi 3009ce57dfc1SAl Viro if (error < 0) 30102675a4ebSAl Viro goto out; 3011a1eb3315SMiklos Szeredi 301237d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3013b6183df7SMiklos Szeredi } else { 3014fe2d35ffSAl Viro /* create side of things */ 3015a3fbbde7SAl Viro /* 3016b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3017b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3018b6183df7SMiklos Szeredi * about to look up 3019a3fbbde7SAl Viro */ 30209f1fafeeSAl Viro error = complete_walk(nd); 3021191d7f73SAl Viro if (error) { 3022191d7f73SAl Viro if (nd->depth) 3023191d7f73SAl Viro put_link(nd); 30242675a4ebSAl Viro return error; 3025191d7f73SAl Viro } 3026fe2d35ffSAl Viro 302733e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 302816c2cd71SAl Viro error = -EISDIR; 30291f36f774SAl Viro /* trailing slashes? */ 303031e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 30312675a4ebSAl Viro goto out; 3032b6183df7SMiklos Szeredi } 30331f36f774SAl Viro 303416b1c1cdSMiklos Szeredi retry_lookup: 303564894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 303664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 303764894cf8SAl Viro if (!error) 303864894cf8SAl Viro got_write = true; 303964894cf8SAl Viro /* 304064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 304164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 304264894cf8SAl Viro * dropping this one anyway. 304364894cf8SAl Viro */ 304464894cf8SAl Viro } 3045a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3046896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3047fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3048fb1cc555SAl Viro 30492675a4ebSAl Viro if (error <= 0) { 30502675a4ebSAl Viro if (error) 3051d58ffd35SMiklos Szeredi goto out; 30526c0d46c4SAl Viro 305347237687SAl Viro if ((*opened & FILE_CREATED) || 3054496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 305577d660a8SMiklos Szeredi will_truncate = false; 3056d18e9008SMiklos Szeredi 3057adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3058d18e9008SMiklos Szeredi goto opened; 3059d18e9008SMiklos Szeredi } 3060d18e9008SMiklos Szeredi 306147237687SAl Viro if (*opened & FILE_CREATED) { 30629b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3063ca344a89SAl Viro open_flag &= ~O_TRUNC; 306477d660a8SMiklos Szeredi will_truncate = false; 3065bcda7652SAl Viro acc_mode = MAY_OPEN; 3066896475d5SAl Viro path_to_nameidata(&path, nd); 3067e83db167SMiklos Szeredi goto finish_open_created; 3068fb1cc555SAl Viro } 3069fb1cc555SAl Viro 3070fb1cc555SAl Viro /* 30713134f37eSJeff Layton * create/update audit record if it already exists. 3072fb1cc555SAl Viro */ 3073896475d5SAl Viro if (d_is_positive(path.dentry)) 3074896475d5SAl Viro audit_inode(name, path.dentry, 0); 3075fb1cc555SAl Viro 3076d18e9008SMiklos Szeredi /* 3077d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3078d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3079d18e9008SMiklos Szeredi * necessary...) 3080d18e9008SMiklos Szeredi */ 308164894cf8SAl Viro if (got_write) { 3082d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 308364894cf8SAl Viro got_write = false; 3084d18e9008SMiklos Szeredi } 3085d18e9008SMiklos Szeredi 3086fb1cc555SAl Viro error = -EEXIST; 3087f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3088fb1cc555SAl Viro goto exit_dput; 3089fb1cc555SAl Viro 3090756daf26SNeilBrown error = follow_managed(&path, nd); 30919875cf80SDavid Howells if (error < 0) 30928402752eSAl Viro goto out; 3093a3fbbde7SAl Viro 3094decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3095896475d5SAl Viro inode = path.dentry->d_inode; 3096fb1cc555SAl Viro error = -ENOENT; 3097896475d5SAl Viro if (d_is_negative(path.dentry)) { 3098896475d5SAl Viro path_to_nameidata(&path, nd); 30992675a4ebSAl Viro goto out; 310054c33e7fSMiklos Szeredi } 3101766c4cbfSAl Viro finish_lookup: 3102191d7f73SAl Viro if (nd->depth) 3103191d7f73SAl Viro put_link(nd); 3104d63ff28fSAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW); 3105d63ff28fSAl Viro if (unlikely(error)) { 3106d63ff28fSAl Viro if (error < 0) 3107d63ff28fSAl Viro goto out; 3108d63ff28fSAl Viro return error; 3109d45ea867SMiklos Szeredi } 3110fb1cc555SAl Viro 3111896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3112896475d5SAl Viro path_to_nameidata(&path, nd); 3113a5cfe2d5SAl Viro error = -ELOOP; 3114a5cfe2d5SAl Viro goto out; 3115a5cfe2d5SAl Viro } 3116a5cfe2d5SAl Viro 3117896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3118896475d5SAl Viro path_to_nameidata(&path, nd); 311916b1c1cdSMiklos Szeredi } else { 312016b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3121896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3122896475d5SAl Viro nd->path.dentry = path.dentry; 312316b1c1cdSMiklos Szeredi 312416b1c1cdSMiklos Szeredi } 3125decf3400SMiklos Szeredi nd->inode = inode; 3126a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3127bc77daa7SAl Viro finish_open: 3128a3fbbde7SAl Viro error = complete_walk(nd); 312916b1c1cdSMiklos Szeredi if (error) { 3130191d7f73SAl Viro if (nd->depth) 3131191d7f73SAl Viro put_link(nd); 313216b1c1cdSMiklos Szeredi path_put(&save_parent); 31332675a4ebSAl Viro return error; 313416b1c1cdSMiklos Szeredi } 3135bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3136fb1cc555SAl Viro error = -EISDIR; 313744b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31382675a4ebSAl Viro goto out; 3139af2f5542SMiklos Szeredi error = -ENOTDIR; 314044b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31412675a4ebSAl Viro goto out; 31424bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 314377d660a8SMiklos Szeredi will_truncate = false; 31446c0d46c4SAl Viro 31450f9d1a10SAl Viro if (will_truncate) { 31460f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31470f9d1a10SAl Viro if (error) 31482675a4ebSAl Viro goto out; 314964894cf8SAl Viro got_write = true; 31500f9d1a10SAl Viro } 3151e83db167SMiklos Szeredi finish_open_created: 3152bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3153ca344a89SAl Viro if (error) 31542675a4ebSAl Viro goto out; 31554aa7c634SMiklos Szeredi 31564aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31574aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31584aa7c634SMiklos Szeredi if (!error) { 31594aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31604aa7c634SMiklos Szeredi } else { 316130d90494SAl Viro if (error == -EOPENSTALE) 3162f60dc3dbSMiklos Szeredi goto stale_open; 3163015c3bbcSMiklos Szeredi goto out; 3164f60dc3dbSMiklos Szeredi } 3165a8277b9bSMiklos Szeredi opened: 31662675a4ebSAl Viro error = open_check_o_direct(file); 3167015c3bbcSMiklos Szeredi if (error) 3168015c3bbcSMiklos Szeredi goto exit_fput; 31693034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3170aa4caadbSMiklos Szeredi if (error) 3171aa4caadbSMiklos Szeredi goto exit_fput; 3172aa4caadbSMiklos Szeredi 31730f9d1a10SAl Viro if (will_truncate) { 31742675a4ebSAl Viro error = handle_truncate(file); 3175aa4caadbSMiklos Szeredi if (error) 3176aa4caadbSMiklos Szeredi goto exit_fput; 31770f9d1a10SAl Viro } 3178ca344a89SAl Viro out: 317964894cf8SAl Viro if (got_write) 31800f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 318116b1c1cdSMiklos Szeredi path_put(&save_parent); 3182e276ae67SMiklos Szeredi terminate_walk(nd); 31832675a4ebSAl Viro return error; 3184fb1cc555SAl Viro 3185fb1cc555SAl Viro exit_dput: 3186896475d5SAl Viro path_put_conditional(&path, nd); 3187ca344a89SAl Viro goto out; 3188015c3bbcSMiklos Szeredi exit_fput: 31892675a4ebSAl Viro fput(file); 31902675a4ebSAl Viro goto out; 3191015c3bbcSMiklos Szeredi 3192f60dc3dbSMiklos Szeredi stale_open: 3193f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3194f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3195f60dc3dbSMiklos Szeredi goto out; 3196f60dc3dbSMiklos Szeredi 3197f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3198f60dc3dbSMiklos Szeredi path_put(&nd->path); 3199f60dc3dbSMiklos Szeredi nd->path = save_parent; 3200f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3201f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3202f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 320364894cf8SAl Viro if (got_write) { 3204f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 320564894cf8SAl Viro got_write = false; 3206f60dc3dbSMiklos Szeredi } 3207f60dc3dbSMiklos Szeredi retried = true; 3208f60dc3dbSMiklos Szeredi goto retry_lookup; 3209fb1cc555SAl Viro } 3210fb1cc555SAl Viro 321160545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 321260545d0dSAl Viro struct nameidata *nd, int flags, 321360545d0dSAl Viro const struct open_flags *op, 321460545d0dSAl Viro struct file *file, int *opened) 321560545d0dSAl Viro { 321660545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 321760545d0dSAl Viro struct dentry *dentry, *child; 321860545d0dSAl Viro struct inode *dir; 32195eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 322060545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 322160545d0dSAl Viro if (unlikely(error)) 322260545d0dSAl Viro return error; 322360545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 322460545d0dSAl Viro if (unlikely(error)) 322560545d0dSAl Viro goto out; 322660545d0dSAl Viro /* we want directory to be writable */ 322760545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 322860545d0dSAl Viro if (error) 322960545d0dSAl Viro goto out2; 323060545d0dSAl Viro dentry = nd->path.dentry; 323160545d0dSAl Viro dir = dentry->d_inode; 323260545d0dSAl Viro if (!dir->i_op->tmpfile) { 323360545d0dSAl Viro error = -EOPNOTSUPP; 323460545d0dSAl Viro goto out2; 323560545d0dSAl Viro } 323660545d0dSAl Viro child = d_alloc(dentry, &name); 323760545d0dSAl Viro if (unlikely(!child)) { 323860545d0dSAl Viro error = -ENOMEM; 323960545d0dSAl Viro goto out2; 324060545d0dSAl Viro } 324160545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 324260545d0dSAl Viro nd->flags |= op->intent; 324360545d0dSAl Viro dput(nd->path.dentry); 324460545d0dSAl Viro nd->path.dentry = child; 324560545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 324660545d0dSAl Viro if (error) 324760545d0dSAl Viro goto out2; 324860545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 324969a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 325069a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 325160545d0dSAl Viro if (error) 325260545d0dSAl Viro goto out2; 325360545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 325460545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 325560545d0dSAl Viro if (error) 325660545d0dSAl Viro goto out2; 325760545d0dSAl Viro error = open_check_o_direct(file); 3258f4e0c30cSAl Viro if (error) { 325960545d0dSAl Viro fput(file); 3260f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3261f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3262f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3263f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3264f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3265f4e0c30cSAl Viro } 326660545d0dSAl Viro out2: 326760545d0dSAl Viro mnt_drop_write(nd->path.mnt); 326860545d0dSAl Viro out: 326960545d0dSAl Viro path_put(&nd->path); 327060545d0dSAl Viro return error; 327160545d0dSAl Viro } 327260545d0dSAl Viro 3273669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 327473d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32751da177e4SLinus Torvalds { 327630d90494SAl Viro struct file *file; 327747237687SAl Viro int opened = 0; 327813aab428SAl Viro int error; 327931e6b01fSNick Piggin 328030d90494SAl Viro file = get_empty_filp(); 32811afc99beSAl Viro if (IS_ERR(file)) 32821afc99beSAl Viro return file; 328331e6b01fSNick Piggin 328430d90494SAl Viro file->f_flags = op->open_flag; 328531e6b01fSNick Piggin 3286bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 328760545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3288f15133dfSAl Viro goto out2; 328960545d0dSAl Viro } 329060545d0dSAl Viro 32916e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 329231e6b01fSNick Piggin if (unlikely(error)) 32932675a4ebSAl Viro goto out; 32941da177e4SLinus Torvalds 3295191d7f73SAl Viro while ((error = do_last(nd, file, op, &opened, pathname)) > 0) { 329673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32971d8e03d3SAl Viro error = trailing_symlink(nd); 3298c3e380b0SAl Viro if (unlikely(error)) 32992675a4ebSAl Viro break; 3300806b681cSAl Viro } 330110fa8e62SAl Viro out: 3302893b7775SAl Viro path_cleanup(nd); 3303f15133dfSAl Viro out2: 33042675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33052675a4ebSAl Viro BUG_ON(!error); 330630d90494SAl Viro put_filp(file); 3307015c3bbcSMiklos Szeredi } 33082675a4ebSAl Viro if (unlikely(error)) { 33092675a4ebSAl Viro if (error == -EOPENSTALE) { 33102675a4ebSAl Viro if (flags & LOOKUP_RCU) 33112675a4ebSAl Viro error = -ECHILD; 33122675a4ebSAl Viro else 33132675a4ebSAl Viro error = -ESTALE; 33142675a4ebSAl Viro } 33152675a4ebSAl Viro file = ERR_PTR(error); 33162675a4ebSAl Viro } 33172675a4ebSAl Viro return file; 3318de459215SKirill Korotaev } 33191da177e4SLinus Torvalds 3320669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3321f9652e10SAl Viro const struct open_flags *op) 332213aab428SAl Viro { 3323756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3324f9652e10SAl Viro int flags = op->lookup_flags; 332513aab428SAl Viro struct file *filp; 332613aab428SAl Viro 332773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 332813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 332973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 333013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 333173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3332756daf26SNeilBrown restore_nameidata(saved_nd); 333313aab428SAl Viro return filp; 333413aab428SAl Viro } 333513aab428SAl Viro 333673d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3337f9652e10SAl Viro const char *name, const struct open_flags *op) 333873d049a4SAl Viro { 3339756daf26SNeilBrown struct nameidata nd, *saved_nd; 334073d049a4SAl Viro struct file *file; 334151689104SPaul Moore struct filename *filename; 3342f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 334373d049a4SAl Viro 334473d049a4SAl Viro nd.root.mnt = mnt; 334573d049a4SAl Viro nd.root.dentry = dentry; 334673d049a4SAl Viro 3347b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 334873d049a4SAl Viro return ERR_PTR(-ELOOP); 334973d049a4SAl Viro 335051689104SPaul Moore filename = getname_kernel(name); 335151689104SPaul Moore if (unlikely(IS_ERR(filename))) 335251689104SPaul Moore return ERR_CAST(filename); 335351689104SPaul Moore 3354756daf26SNeilBrown saved_nd = set_nameidata(&nd); 335551689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 335673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 335751689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 335873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 335951689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3360756daf26SNeilBrown restore_nameidata(saved_nd); 336151689104SPaul Moore putname(filename); 336273d049a4SAl Viro return file; 336373d049a4SAl Viro } 336473d049a4SAl Viro 3365fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33661ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33671da177e4SLinus Torvalds { 3368c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3369ed75e95dSAl Viro struct nameidata nd; 3370c30dabfeSJan Kara int err2; 33711ac12b4bSJeff Layton int error; 33721ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33731ac12b4bSJeff Layton 33741ac12b4bSJeff Layton /* 33751ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33761ac12b4bSJeff Layton * other flags passed in are ignored! 33771ac12b4bSJeff Layton */ 33781ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33791ac12b4bSJeff Layton 3380fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3381ed75e95dSAl Viro if (error) 3382ed75e95dSAl Viro return ERR_PTR(error); 33831da177e4SLinus Torvalds 3384c663e5d8SChristoph Hellwig /* 3385c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3386c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3387c663e5d8SChristoph Hellwig */ 3388ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3389ed75e95dSAl Viro goto out; 3390ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3391ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3392c663e5d8SChristoph Hellwig 3393c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3394c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3395c663e5d8SChristoph Hellwig /* 3396c663e5d8SChristoph Hellwig * Do the final lookup. 3397c663e5d8SChristoph Hellwig */ 3398ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33996a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 34001da177e4SLinus Torvalds if (IS_ERR(dentry)) 3401a8104a9fSAl Viro goto unlock; 3402c663e5d8SChristoph Hellwig 3403a8104a9fSAl Viro error = -EEXIST; 3404b18825a7SDavid Howells if (d_is_positive(dentry)) 3405a8104a9fSAl Viro goto fail; 3406b18825a7SDavid Howells 3407c663e5d8SChristoph Hellwig /* 3408c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3409c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3410c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3411c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3412c663e5d8SChristoph Hellwig */ 3413ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3414a8104a9fSAl Viro error = -ENOENT; 3415ed75e95dSAl Viro goto fail; 3416e9baf6e5SAl Viro } 3417c30dabfeSJan Kara if (unlikely(err2)) { 3418c30dabfeSJan Kara error = err2; 3419a8104a9fSAl Viro goto fail; 3420c30dabfeSJan Kara } 3421ed75e95dSAl Viro *path = nd.path; 3422e9baf6e5SAl Viro return dentry; 34231da177e4SLinus Torvalds fail: 3424a8104a9fSAl Viro dput(dentry); 3425a8104a9fSAl Viro dentry = ERR_PTR(error); 3426a8104a9fSAl Viro unlock: 3427dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3428c30dabfeSJan Kara if (!err2) 3429c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3430ed75e95dSAl Viro out: 3431dae6ad8fSAl Viro path_put(&nd.path); 3432ed75e95dSAl Viro return dentry; 3433dae6ad8fSAl Viro } 3434fa14a0b8SAl Viro 3435fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3436fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3437fa14a0b8SAl Viro { 343851689104SPaul Moore struct filename *filename = getname_kernel(pathname); 343951689104SPaul Moore struct dentry *res; 344051689104SPaul Moore 344151689104SPaul Moore if (IS_ERR(filename)) 344251689104SPaul Moore return ERR_CAST(filename); 344351689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 344451689104SPaul Moore putname(filename); 344551689104SPaul Moore return res; 3446fa14a0b8SAl Viro } 3447dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3448dae6ad8fSAl Viro 3449921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3450921a1650SAl Viro { 3451921a1650SAl Viro dput(dentry); 3452921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3453a8104a9fSAl Viro mnt_drop_write(path->mnt); 3454921a1650SAl Viro path_put(path); 3455921a1650SAl Viro } 3456921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3457921a1650SAl Viro 34581ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34591ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3460dae6ad8fSAl Viro { 346191a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3462dae6ad8fSAl Viro struct dentry *res; 3463dae6ad8fSAl Viro if (IS_ERR(tmp)) 3464dae6ad8fSAl Viro return ERR_CAST(tmp); 3465fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3466dae6ad8fSAl Viro putname(tmp); 3467dae6ad8fSAl Viro return res; 3468dae6ad8fSAl Viro } 3469dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3470dae6ad8fSAl Viro 34711a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34721da177e4SLinus Torvalds { 3473a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34741da177e4SLinus Torvalds 34751da177e4SLinus Torvalds if (error) 34761da177e4SLinus Torvalds return error; 34771da177e4SLinus Torvalds 3478975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34791da177e4SLinus Torvalds return -EPERM; 34801da177e4SLinus Torvalds 3481acfa4380SAl Viro if (!dir->i_op->mknod) 34821da177e4SLinus Torvalds return -EPERM; 34831da177e4SLinus Torvalds 348408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 348508ce5f16SSerge E. Hallyn if (error) 348608ce5f16SSerge E. Hallyn return error; 348708ce5f16SSerge E. Hallyn 34881da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34891da177e4SLinus Torvalds if (error) 34901da177e4SLinus Torvalds return error; 34911da177e4SLinus Torvalds 34921da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3493a74574aaSStephen Smalley if (!error) 3494f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34951da177e4SLinus Torvalds return error; 34961da177e4SLinus Torvalds } 34974d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34981da177e4SLinus Torvalds 3499f69aac00SAl Viro static int may_mknod(umode_t mode) 3500463c3197SDave Hansen { 3501463c3197SDave Hansen switch (mode & S_IFMT) { 3502463c3197SDave Hansen case S_IFREG: 3503463c3197SDave Hansen case S_IFCHR: 3504463c3197SDave Hansen case S_IFBLK: 3505463c3197SDave Hansen case S_IFIFO: 3506463c3197SDave Hansen case S_IFSOCK: 3507463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3508463c3197SDave Hansen return 0; 3509463c3197SDave Hansen case S_IFDIR: 3510463c3197SDave Hansen return -EPERM; 3511463c3197SDave Hansen default: 3512463c3197SDave Hansen return -EINVAL; 3513463c3197SDave Hansen } 3514463c3197SDave Hansen } 3515463c3197SDave Hansen 35168208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35172e4d0924SHeiko Carstens unsigned, dev) 35181da177e4SLinus Torvalds { 35191da177e4SLinus Torvalds struct dentry *dentry; 3520dae6ad8fSAl Viro struct path path; 3521dae6ad8fSAl Viro int error; 3522972567f1SJeff Layton unsigned int lookup_flags = 0; 35231da177e4SLinus Torvalds 35248e4bfca1SAl Viro error = may_mknod(mode); 35258e4bfca1SAl Viro if (error) 35268e4bfca1SAl Viro return error; 3527972567f1SJeff Layton retry: 3528972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3529dae6ad8fSAl Viro if (IS_ERR(dentry)) 3530dae6ad8fSAl Viro return PTR_ERR(dentry); 35312ad94ae6SAl Viro 3532dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3533ce3b0f8dSAl Viro mode &= ~current_umask(); 3534dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3535be6d3e56SKentaro Takeda if (error) 3536a8104a9fSAl Viro goto out; 35371da177e4SLinus Torvalds switch (mode & S_IFMT) { 35381da177e4SLinus Torvalds case 0: case S_IFREG: 3539312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35401da177e4SLinus Torvalds break; 35411da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3542dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35431da177e4SLinus Torvalds new_decode_dev(dev)); 35441da177e4SLinus Torvalds break; 35451da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3546dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35471da177e4SLinus Torvalds break; 35481da177e4SLinus Torvalds } 3549a8104a9fSAl Viro out: 3550921a1650SAl Viro done_path_create(&path, dentry); 3551972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3552972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3553972567f1SJeff Layton goto retry; 3554972567f1SJeff Layton } 35551da177e4SLinus Torvalds return error; 35561da177e4SLinus Torvalds } 35571da177e4SLinus Torvalds 35588208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35595590ff0dSUlrich Drepper { 35605590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35615590ff0dSUlrich Drepper } 35625590ff0dSUlrich Drepper 356318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35641da177e4SLinus Torvalds { 3565a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35668de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35671da177e4SLinus Torvalds 35681da177e4SLinus Torvalds if (error) 35691da177e4SLinus Torvalds return error; 35701da177e4SLinus Torvalds 3571acfa4380SAl Viro if (!dir->i_op->mkdir) 35721da177e4SLinus Torvalds return -EPERM; 35731da177e4SLinus Torvalds 35741da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35751da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35761da177e4SLinus Torvalds if (error) 35771da177e4SLinus Torvalds return error; 35781da177e4SLinus Torvalds 35798de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35808de52778SAl Viro return -EMLINK; 35818de52778SAl Viro 35821da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3583a74574aaSStephen Smalley if (!error) 3584f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35851da177e4SLinus Torvalds return error; 35861da177e4SLinus Torvalds } 35874d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35881da177e4SLinus Torvalds 3589a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35901da177e4SLinus Torvalds { 35916902d925SDave Hansen struct dentry *dentry; 3592dae6ad8fSAl Viro struct path path; 3593dae6ad8fSAl Viro int error; 3594b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35951da177e4SLinus Torvalds 3596b76d8b82SJeff Layton retry: 3597b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35986902d925SDave Hansen if (IS_ERR(dentry)) 3599dae6ad8fSAl Viro return PTR_ERR(dentry); 36006902d925SDave Hansen 3601dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3602ce3b0f8dSAl Viro mode &= ~current_umask(); 3603dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3604a8104a9fSAl Viro if (!error) 3605dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3606921a1650SAl Viro done_path_create(&path, dentry); 3607b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3608b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3609b76d8b82SJeff Layton goto retry; 3610b76d8b82SJeff Layton } 36111da177e4SLinus Torvalds return error; 36121da177e4SLinus Torvalds } 36131da177e4SLinus Torvalds 3614a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36155590ff0dSUlrich Drepper { 36165590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36175590ff0dSUlrich Drepper } 36185590ff0dSUlrich Drepper 36191da177e4SLinus Torvalds /* 3620a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3621c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3622a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3623a71905f0SSage Weil * then we drop the dentry now. 36241da177e4SLinus Torvalds * 36251da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36261da177e4SLinus Torvalds * do a 36271da177e4SLinus Torvalds * 36281da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36291da177e4SLinus Torvalds * return -EBUSY; 36301da177e4SLinus Torvalds * 36311da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36321da177e4SLinus Torvalds * that is still in use by something else.. 36331da177e4SLinus Torvalds */ 36341da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36351da177e4SLinus Torvalds { 36361da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36371da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 363898474236SWaiman Long if (dentry->d_lockref.count == 1) 36391da177e4SLinus Torvalds __d_drop(dentry); 36401da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36411da177e4SLinus Torvalds } 36424d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36431da177e4SLinus Torvalds 36441da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36451da177e4SLinus Torvalds { 36461da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36471da177e4SLinus Torvalds 36481da177e4SLinus Torvalds if (error) 36491da177e4SLinus Torvalds return error; 36501da177e4SLinus Torvalds 3651acfa4380SAl Viro if (!dir->i_op->rmdir) 36521da177e4SLinus Torvalds return -EPERM; 36531da177e4SLinus Torvalds 36541d2ef590SAl Viro dget(dentry); 36551b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3656912dbc15SSage Weil 36571da177e4SLinus Torvalds error = -EBUSY; 36587af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3659912dbc15SSage Weil goto out; 3660912dbc15SSage Weil 36611da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3662912dbc15SSage Weil if (error) 3663912dbc15SSage Weil goto out; 3664912dbc15SSage Weil 36653cebde24SSage Weil shrink_dcache_parent(dentry); 36661da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3667912dbc15SSage Weil if (error) 3668912dbc15SSage Weil goto out; 3669912dbc15SSage Weil 36701da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3671d83c49f3SAl Viro dont_mount(dentry); 36728ed936b5SEric W. Biederman detach_mounts(dentry); 36731da177e4SLinus Torvalds 3674912dbc15SSage Weil out: 3675912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36761d2ef590SAl Viro dput(dentry); 3677912dbc15SSage Weil if (!error) 3678912dbc15SSage Weil d_delete(dentry); 36791da177e4SLinus Torvalds return error; 36801da177e4SLinus Torvalds } 36814d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36821da177e4SLinus Torvalds 36835590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36841da177e4SLinus Torvalds { 36851da177e4SLinus Torvalds int error = 0; 368691a27b2aSJeff Layton struct filename *name; 36871da177e4SLinus Torvalds struct dentry *dentry; 3688f5beed75SAl Viro struct path path; 3689f5beed75SAl Viro struct qstr last; 3690f5beed75SAl Viro int type; 3691c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3692c6ee9206SJeff Layton retry: 3693f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3694f5beed75SAl Viro &path, &last, &type, lookup_flags); 369591a27b2aSJeff Layton if (IS_ERR(name)) 369691a27b2aSJeff Layton return PTR_ERR(name); 36971da177e4SLinus Torvalds 3698f5beed75SAl Viro switch (type) { 36991da177e4SLinus Torvalds case LAST_DOTDOT: 37001da177e4SLinus Torvalds error = -ENOTEMPTY; 37011da177e4SLinus Torvalds goto exit1; 37021da177e4SLinus Torvalds case LAST_DOT: 37031da177e4SLinus Torvalds error = -EINVAL; 37041da177e4SLinus Torvalds goto exit1; 37051da177e4SLinus Torvalds case LAST_ROOT: 37061da177e4SLinus Torvalds error = -EBUSY; 37071da177e4SLinus Torvalds goto exit1; 37081da177e4SLinus Torvalds } 37090612d9fbSOGAWA Hirofumi 3710f5beed75SAl Viro error = mnt_want_write(path.mnt); 3711c30dabfeSJan Kara if (error) 3712c30dabfeSJan Kara goto exit1; 37130612d9fbSOGAWA Hirofumi 3714f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3715f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37161da177e4SLinus Torvalds error = PTR_ERR(dentry); 37176902d925SDave Hansen if (IS_ERR(dentry)) 37186902d925SDave Hansen goto exit2; 3719e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3720e6bc45d6STheodore Ts'o error = -ENOENT; 3721e6bc45d6STheodore Ts'o goto exit3; 3722e6bc45d6STheodore Ts'o } 3723f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3724be6d3e56SKentaro Takeda if (error) 3725c30dabfeSJan Kara goto exit3; 3726f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37270622753bSDave Hansen exit3: 37281da177e4SLinus Torvalds dput(dentry); 37296902d925SDave Hansen exit2: 3730f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3731f5beed75SAl Viro mnt_drop_write(path.mnt); 37321da177e4SLinus Torvalds exit1: 3733f5beed75SAl Viro path_put(&path); 37341da177e4SLinus Torvalds putname(name); 3735c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3736c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3737c6ee9206SJeff Layton goto retry; 3738c6ee9206SJeff Layton } 37391da177e4SLinus Torvalds return error; 37401da177e4SLinus Torvalds } 37411da177e4SLinus Torvalds 37423cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37435590ff0dSUlrich Drepper { 37445590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37455590ff0dSUlrich Drepper } 37465590ff0dSUlrich Drepper 3747b21996e3SJ. Bruce Fields /** 3748b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3749b21996e3SJ. Bruce Fields * @dir: parent directory 3750b21996e3SJ. Bruce Fields * @dentry: victim 3751b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3752b21996e3SJ. Bruce Fields * 3753b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3754b21996e3SJ. Bruce Fields * 3755b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3756b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3757b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3758b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3759b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3760b21996e3SJ. Bruce Fields * 3761b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3762b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3763b21996e3SJ. Bruce Fields * to be NFS exported. 3764b21996e3SJ. Bruce Fields */ 3765b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37661da177e4SLinus Torvalds { 37679accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37681da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37691da177e4SLinus Torvalds 37701da177e4SLinus Torvalds if (error) 37711da177e4SLinus Torvalds return error; 37721da177e4SLinus Torvalds 3773acfa4380SAl Viro if (!dir->i_op->unlink) 37741da177e4SLinus Torvalds return -EPERM; 37751da177e4SLinus Torvalds 37769accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37778ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37781da177e4SLinus Torvalds error = -EBUSY; 37791da177e4SLinus Torvalds else { 37801da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3781bec1052eSAl Viro if (!error) { 37825a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37835a14696cSJ. Bruce Fields if (error) 3784b21996e3SJ. Bruce Fields goto out; 37851da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37868ed936b5SEric W. Biederman if (!error) { 3787d83c49f3SAl Viro dont_mount(dentry); 37888ed936b5SEric W. Biederman detach_mounts(dentry); 37898ed936b5SEric W. Biederman } 3790bec1052eSAl Viro } 37911da177e4SLinus Torvalds } 3792b21996e3SJ. Bruce Fields out: 37939accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37941da177e4SLinus Torvalds 37951da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37961da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37979accbb97SJ. Bruce Fields fsnotify_link_count(target); 37981da177e4SLinus Torvalds d_delete(dentry); 37991da177e4SLinus Torvalds } 38000eeca283SRobert Love 38011da177e4SLinus Torvalds return error; 38021da177e4SLinus Torvalds } 38034d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38041da177e4SLinus Torvalds 38051da177e4SLinus Torvalds /* 38061da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38071b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38081da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38091da177e4SLinus Torvalds * while waiting on the I/O. 38101da177e4SLinus Torvalds */ 38115590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38121da177e4SLinus Torvalds { 38132ad94ae6SAl Viro int error; 381491a27b2aSJeff Layton struct filename *name; 38151da177e4SLinus Torvalds struct dentry *dentry; 3816f5beed75SAl Viro struct path path; 3817f5beed75SAl Viro struct qstr last; 3818f5beed75SAl Viro int type; 38191da177e4SLinus Torvalds struct inode *inode = NULL; 3820b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38215d18f813SJeff Layton unsigned int lookup_flags = 0; 38225d18f813SJeff Layton retry: 3823f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3824f5beed75SAl Viro &path, &last, &type, lookup_flags); 382591a27b2aSJeff Layton if (IS_ERR(name)) 382691a27b2aSJeff Layton return PTR_ERR(name); 38272ad94ae6SAl Viro 38281da177e4SLinus Torvalds error = -EISDIR; 3829f5beed75SAl Viro if (type != LAST_NORM) 38301da177e4SLinus Torvalds goto exit1; 38310612d9fbSOGAWA Hirofumi 3832f5beed75SAl Viro error = mnt_want_write(path.mnt); 3833c30dabfeSJan Kara if (error) 3834c30dabfeSJan Kara goto exit1; 3835b21996e3SJ. Bruce Fields retry_deleg: 3836f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3837f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38381da177e4SLinus Torvalds error = PTR_ERR(dentry); 38391da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38401da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3841f5beed75SAl Viro if (last.name[last.len]) 384250338b88STörök Edwin goto slashes; 38431da177e4SLinus Torvalds inode = dentry->d_inode; 3844b18825a7SDavid Howells if (d_is_negative(dentry)) 3845e6bc45d6STheodore Ts'o goto slashes; 38467de9c6eeSAl Viro ihold(inode); 3847f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3848be6d3e56SKentaro Takeda if (error) 3849c30dabfeSJan Kara goto exit2; 3850f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38511da177e4SLinus Torvalds exit2: 38521da177e4SLinus Torvalds dput(dentry); 38531da177e4SLinus Torvalds } 3854f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38551da177e4SLinus Torvalds if (inode) 38561da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3857b21996e3SJ. Bruce Fields inode = NULL; 3858b21996e3SJ. Bruce Fields if (delegated_inode) { 38595a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3860b21996e3SJ. Bruce Fields if (!error) 3861b21996e3SJ. Bruce Fields goto retry_deleg; 3862b21996e3SJ. Bruce Fields } 3863f5beed75SAl Viro mnt_drop_write(path.mnt); 38641da177e4SLinus Torvalds exit1: 3865f5beed75SAl Viro path_put(&path); 38661da177e4SLinus Torvalds putname(name); 38675d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38685d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38695d18f813SJeff Layton inode = NULL; 38705d18f813SJeff Layton goto retry; 38715d18f813SJeff Layton } 38721da177e4SLinus Torvalds return error; 38731da177e4SLinus Torvalds 38741da177e4SLinus Torvalds slashes: 3875b18825a7SDavid Howells if (d_is_negative(dentry)) 3876b18825a7SDavid Howells error = -ENOENT; 387744b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3878b18825a7SDavid Howells error = -EISDIR; 3879b18825a7SDavid Howells else 3880b18825a7SDavid Howells error = -ENOTDIR; 38811da177e4SLinus Torvalds goto exit2; 38821da177e4SLinus Torvalds } 38831da177e4SLinus Torvalds 38842e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38855590ff0dSUlrich Drepper { 38865590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38875590ff0dSUlrich Drepper return -EINVAL; 38885590ff0dSUlrich Drepper 38895590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38905590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38915590ff0dSUlrich Drepper 38925590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38935590ff0dSUlrich Drepper } 38945590ff0dSUlrich Drepper 38953480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38965590ff0dSUlrich Drepper { 38975590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38985590ff0dSUlrich Drepper } 38995590ff0dSUlrich Drepper 3900db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39011da177e4SLinus Torvalds { 3902a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39031da177e4SLinus Torvalds 39041da177e4SLinus Torvalds if (error) 39051da177e4SLinus Torvalds return error; 39061da177e4SLinus Torvalds 3907acfa4380SAl Viro if (!dir->i_op->symlink) 39081da177e4SLinus Torvalds return -EPERM; 39091da177e4SLinus Torvalds 39101da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39111da177e4SLinus Torvalds if (error) 39121da177e4SLinus Torvalds return error; 39131da177e4SLinus Torvalds 39141da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3915a74574aaSStephen Smalley if (!error) 3916f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39171da177e4SLinus Torvalds return error; 39181da177e4SLinus Torvalds } 39194d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39201da177e4SLinus Torvalds 39212e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39222e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39231da177e4SLinus Torvalds { 39242ad94ae6SAl Viro int error; 392591a27b2aSJeff Layton struct filename *from; 39266902d925SDave Hansen struct dentry *dentry; 3927dae6ad8fSAl Viro struct path path; 3928f46d3567SJeff Layton unsigned int lookup_flags = 0; 39291da177e4SLinus Torvalds 39301da177e4SLinus Torvalds from = getname(oldname); 39311da177e4SLinus Torvalds if (IS_ERR(from)) 39321da177e4SLinus Torvalds return PTR_ERR(from); 3933f46d3567SJeff Layton retry: 3934f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39351da177e4SLinus Torvalds error = PTR_ERR(dentry); 39366902d925SDave Hansen if (IS_ERR(dentry)) 3937dae6ad8fSAl Viro goto out_putname; 39386902d925SDave Hansen 393991a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3940a8104a9fSAl Viro if (!error) 394191a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3942921a1650SAl Viro done_path_create(&path, dentry); 3943f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3944f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3945f46d3567SJeff Layton goto retry; 3946f46d3567SJeff Layton } 39476902d925SDave Hansen out_putname: 39481da177e4SLinus Torvalds putname(from); 39491da177e4SLinus Torvalds return error; 39501da177e4SLinus Torvalds } 39511da177e4SLinus Torvalds 39523480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39535590ff0dSUlrich Drepper { 39545590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39555590ff0dSUlrich Drepper } 39565590ff0dSUlrich Drepper 3957146a8595SJ. Bruce Fields /** 3958146a8595SJ. Bruce Fields * vfs_link - create a new link 3959146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3960146a8595SJ. Bruce Fields * @dir: new parent 3961146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3962146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3963146a8595SJ. Bruce Fields * 3964146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3965146a8595SJ. Bruce Fields * 3966146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3967146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3968146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3969146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3970146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3971146a8595SJ. Bruce Fields * 3972146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3973146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3974146a8595SJ. Bruce Fields * to be NFS exported. 3975146a8595SJ. Bruce Fields */ 3976146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39771da177e4SLinus Torvalds { 39781da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39798de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39801da177e4SLinus Torvalds int error; 39811da177e4SLinus Torvalds 39821da177e4SLinus Torvalds if (!inode) 39831da177e4SLinus Torvalds return -ENOENT; 39841da177e4SLinus Torvalds 3985a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39861da177e4SLinus Torvalds if (error) 39871da177e4SLinus Torvalds return error; 39881da177e4SLinus Torvalds 39891da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39901da177e4SLinus Torvalds return -EXDEV; 39911da177e4SLinus Torvalds 39921da177e4SLinus Torvalds /* 39931da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39941da177e4SLinus Torvalds */ 39951da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39961da177e4SLinus Torvalds return -EPERM; 3997acfa4380SAl Viro if (!dir->i_op->link) 39981da177e4SLinus Torvalds return -EPERM; 39997e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40001da177e4SLinus Torvalds return -EPERM; 40011da177e4SLinus Torvalds 40021da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40031da177e4SLinus Torvalds if (error) 40041da177e4SLinus Torvalds return error; 40051da177e4SLinus Torvalds 40067e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4007aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4008f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4009aae8a97dSAneesh Kumar K.V error = -ENOENT; 40108de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40118de52778SAl Viro error = -EMLINK; 4012146a8595SJ. Bruce Fields else { 4013146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4014146a8595SJ. Bruce Fields if (!error) 40151da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4016146a8595SJ. Bruce Fields } 4017f4e0c30cSAl Viro 4018f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4019f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4020f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4021f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4022f4e0c30cSAl Viro } 40237e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4024e31e14ecSStephen Smalley if (!error) 40257e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40261da177e4SLinus Torvalds return error; 40271da177e4SLinus Torvalds } 40284d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40291da177e4SLinus Torvalds 40301da177e4SLinus Torvalds /* 40311da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40321da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40331da177e4SLinus Torvalds * newname. --KAB 40341da177e4SLinus Torvalds * 40351da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40361da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40371da177e4SLinus Torvalds * and other special files. --ADM 40381da177e4SLinus Torvalds */ 40392e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40402e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40411da177e4SLinus Torvalds { 40421da177e4SLinus Torvalds struct dentry *new_dentry; 4043dae6ad8fSAl Viro struct path old_path, new_path; 4044146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 404511a7b371SAneesh Kumar K.V int how = 0; 40461da177e4SLinus Torvalds int error; 40471da177e4SLinus Torvalds 404811a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4049c04030e1SUlrich Drepper return -EINVAL; 405011a7b371SAneesh Kumar K.V /* 4051f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4052f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4053f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 405411a7b371SAneesh Kumar K.V */ 4055f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4056f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4057f0cc6ffbSLinus Torvalds return -ENOENT; 405811a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4059f0cc6ffbSLinus Torvalds } 4060c04030e1SUlrich Drepper 406111a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 406211a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4063442e31caSJeff Layton retry: 406411a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40651da177e4SLinus Torvalds if (error) 40662ad94ae6SAl Viro return error; 40672ad94ae6SAl Viro 4068442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4069442e31caSJeff Layton (how & LOOKUP_REVAL)); 40701da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40716902d925SDave Hansen if (IS_ERR(new_dentry)) 4072dae6ad8fSAl Viro goto out; 4073dae6ad8fSAl Viro 4074dae6ad8fSAl Viro error = -EXDEV; 4075dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4076dae6ad8fSAl Viro goto out_dput; 4077800179c9SKees Cook error = may_linkat(&old_path); 4078800179c9SKees Cook if (unlikely(error)) 4079800179c9SKees Cook goto out_dput; 4080dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4081be6d3e56SKentaro Takeda if (error) 4082a8104a9fSAl Viro goto out_dput; 4083146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 408475c3f29dSDave Hansen out_dput: 4085921a1650SAl Viro done_path_create(&new_path, new_dentry); 4086146a8595SJ. Bruce Fields if (delegated_inode) { 4087146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4088d22e6338SOleg Drokin if (!error) { 4089d22e6338SOleg Drokin path_put(&old_path); 4090146a8595SJ. Bruce Fields goto retry; 4091146a8595SJ. Bruce Fields } 4092d22e6338SOleg Drokin } 4093442e31caSJeff Layton if (retry_estale(error, how)) { 4094d22e6338SOleg Drokin path_put(&old_path); 4095442e31caSJeff Layton how |= LOOKUP_REVAL; 4096442e31caSJeff Layton goto retry; 4097442e31caSJeff Layton } 40981da177e4SLinus Torvalds out: 40992d8f3038SAl Viro path_put(&old_path); 41001da177e4SLinus Torvalds 41011da177e4SLinus Torvalds return error; 41021da177e4SLinus Torvalds } 41031da177e4SLinus Torvalds 41043480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41055590ff0dSUlrich Drepper { 4106c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41075590ff0dSUlrich Drepper } 41085590ff0dSUlrich Drepper 4109bc27027aSMiklos Szeredi /** 4110bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4111bc27027aSMiklos Szeredi * @old_dir: parent of source 4112bc27027aSMiklos Szeredi * @old_dentry: source 4113bc27027aSMiklos Szeredi * @new_dir: parent of destination 4114bc27027aSMiklos Szeredi * @new_dentry: destination 4115bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4116520c8b16SMiklos Szeredi * @flags: rename flags 4117bc27027aSMiklos Szeredi * 4118bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4119bc27027aSMiklos Szeredi * 4120bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4121bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4122bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4123bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4124bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4125bc27027aSMiklos Szeredi * so. 4126bc27027aSMiklos Szeredi * 4127bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4128bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4129bc27027aSMiklos Szeredi * to be NFS exported. 4130bc27027aSMiklos Szeredi * 41311da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41321da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41331da177e4SLinus Torvalds * Problems: 4134d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41351da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41361da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4137a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41381da177e4SLinus Torvalds * story. 41396cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41406cedba89SJ. Bruce Fields * and source (if it is not a directory). 41411b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41421da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41431da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4144a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41451da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41461da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41471da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4148a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41491da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41501da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41511da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4152e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41531b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41541da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4155c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41561da177e4SLinus Torvalds * locking]. 41571da177e4SLinus Torvalds */ 41581da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41598e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4160520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41611da177e4SLinus Torvalds { 41621da177e4SLinus Torvalds int error; 4163bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 416459b0df21SEric Paris const unsigned char *old_name; 4165bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4166bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4167da1ce067SMiklos Szeredi bool new_is_dir = false; 4168da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41691da177e4SLinus Torvalds 4170bc27027aSMiklos Szeredi if (source == target) 41711da177e4SLinus Torvalds return 0; 41721da177e4SLinus Torvalds 41731da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41741da177e4SLinus Torvalds if (error) 41751da177e4SLinus Torvalds return error; 41761da177e4SLinus Torvalds 4177da1ce067SMiklos Szeredi if (!target) { 4178a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4179da1ce067SMiklos Szeredi } else { 4180da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4181da1ce067SMiklos Szeredi 4182da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41831da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4184da1ce067SMiklos Szeredi else 4185da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4186da1ce067SMiklos Szeredi } 41871da177e4SLinus Torvalds if (error) 41881da177e4SLinus Torvalds return error; 41891da177e4SLinus Torvalds 41907177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41911da177e4SLinus Torvalds return -EPERM; 41921da177e4SLinus Torvalds 4193520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4194520c8b16SMiklos Szeredi return -EINVAL; 4195520c8b16SMiklos Szeredi 4196bc27027aSMiklos Szeredi /* 4197bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4198bc27027aSMiklos Szeredi * we'll need to flip '..'. 4199bc27027aSMiklos Szeredi */ 4200da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4201da1ce067SMiklos Szeredi if (is_dir) { 4202bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4203bc27027aSMiklos Szeredi if (error) 4204bc27027aSMiklos Szeredi return error; 4205bc27027aSMiklos Szeredi } 4206da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4207da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4208da1ce067SMiklos Szeredi if (error) 4209da1ce067SMiklos Szeredi return error; 4210da1ce067SMiklos Szeredi } 4211da1ce067SMiklos Szeredi } 42120eeca283SRobert Love 42130b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42140b3974ebSMiklos Szeredi flags); 4215bc27027aSMiklos Szeredi if (error) 4216bc27027aSMiklos Szeredi return error; 4217bc27027aSMiklos Szeredi 4218bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4219bc27027aSMiklos Szeredi dget(new_dentry); 4220da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4221bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4222bc27027aSMiklos Szeredi else if (target) 4223bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4224bc27027aSMiklos Szeredi 4225bc27027aSMiklos Szeredi error = -EBUSY; 42267af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4227bc27027aSMiklos Szeredi goto out; 4228bc27027aSMiklos Szeredi 4229da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4230bc27027aSMiklos Szeredi error = -EMLINK; 4231da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4232bc27027aSMiklos Szeredi goto out; 4233da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4234da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4235da1ce067SMiklos Szeredi goto out; 4236da1ce067SMiklos Szeredi } 4237da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4238bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4239da1ce067SMiklos Szeredi if (!is_dir) { 4240bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4241bc27027aSMiklos Szeredi if (error) 4242bc27027aSMiklos Szeredi goto out; 4243da1ce067SMiklos Szeredi } 4244da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4245bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4246bc27027aSMiklos Szeredi if (error) 4247bc27027aSMiklos Szeredi goto out; 4248bc27027aSMiklos Szeredi } 42497177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4250520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4251520c8b16SMiklos Szeredi new_dir, new_dentry); 4252520c8b16SMiklos Szeredi } else { 42537177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4254520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4255520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4256520c8b16SMiklos Szeredi } 4257bc27027aSMiklos Szeredi if (error) 4258bc27027aSMiklos Szeredi goto out; 4259bc27027aSMiklos Szeredi 4260da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42611da177e4SLinus Torvalds if (is_dir) 4262bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4263bc27027aSMiklos Szeredi dont_mount(new_dentry); 42648ed936b5SEric W. Biederman detach_mounts(new_dentry); 4265bc27027aSMiklos Szeredi } 4266da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4267da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4268bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4269da1ce067SMiklos Szeredi else 4270da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4271da1ce067SMiklos Szeredi } 4272bc27027aSMiklos Szeredi out: 4273da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4274bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4275bc27027aSMiklos Szeredi else if (target) 4276bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4277bc27027aSMiklos Szeredi dput(new_dentry); 4278da1ce067SMiklos Szeredi if (!error) { 4279123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4280da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4281da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4282da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4283da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4284da1ce067SMiklos Szeredi } 4285da1ce067SMiklos Szeredi } 42860eeca283SRobert Love fsnotify_oldname_free(old_name); 42870eeca283SRobert Love 42881da177e4SLinus Torvalds return error; 42891da177e4SLinus Torvalds } 42904d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42911da177e4SLinus Torvalds 4292520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4293520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42941da177e4SLinus Torvalds { 42951da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42961da177e4SLinus Torvalds struct dentry *trap; 4297f5beed75SAl Viro struct path old_path, new_path; 4298f5beed75SAl Viro struct qstr old_last, new_last; 4299f5beed75SAl Viro int old_type, new_type; 43008e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 430191a27b2aSJeff Layton struct filename *from; 430291a27b2aSJeff Layton struct filename *to; 4303f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4304c6a94284SJeff Layton bool should_retry = false; 43052ad94ae6SAl Viro int error; 4306520c8b16SMiklos Szeredi 43070d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4308da1ce067SMiklos Szeredi return -EINVAL; 4309da1ce067SMiklos Szeredi 43100d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43110d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4312520c8b16SMiklos Szeredi return -EINVAL; 4313520c8b16SMiklos Szeredi 43140d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43150d7a8555SMiklos Szeredi return -EPERM; 43160d7a8555SMiklos Szeredi 4317f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4318f5beed75SAl Viro target_flags = 0; 4319f5beed75SAl Viro 4320c6a94284SJeff Layton retry: 4321f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4322f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 432391a27b2aSJeff Layton if (IS_ERR(from)) { 432491a27b2aSJeff Layton error = PTR_ERR(from); 43251da177e4SLinus Torvalds goto exit; 432691a27b2aSJeff Layton } 43271da177e4SLinus Torvalds 4328f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4329f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 433091a27b2aSJeff Layton if (IS_ERR(to)) { 433191a27b2aSJeff Layton error = PTR_ERR(to); 43321da177e4SLinus Torvalds goto exit1; 433391a27b2aSJeff Layton } 43341da177e4SLinus Torvalds 43351da177e4SLinus Torvalds error = -EXDEV; 4336f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43371da177e4SLinus Torvalds goto exit2; 43381da177e4SLinus Torvalds 43391da177e4SLinus Torvalds error = -EBUSY; 4340f5beed75SAl Viro if (old_type != LAST_NORM) 43411da177e4SLinus Torvalds goto exit2; 43421da177e4SLinus Torvalds 43430a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43440a7c3937SMiklos Szeredi error = -EEXIST; 4345f5beed75SAl Viro if (new_type != LAST_NORM) 43461da177e4SLinus Torvalds goto exit2; 43471da177e4SLinus Torvalds 4348f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4349c30dabfeSJan Kara if (error) 4350c30dabfeSJan Kara goto exit2; 4351c30dabfeSJan Kara 43528e6d782cSJ. Bruce Fields retry_deleg: 4353f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43541da177e4SLinus Torvalds 4355f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43561da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43571da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43581da177e4SLinus Torvalds goto exit3; 43591da177e4SLinus Torvalds /* source must exist */ 43601da177e4SLinus Torvalds error = -ENOENT; 4361b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43621da177e4SLinus Torvalds goto exit4; 4363f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43641da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43651da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43661da177e4SLinus Torvalds goto exit4; 43670a7c3937SMiklos Szeredi error = -EEXIST; 43680a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43690a7c3937SMiklos Szeredi goto exit5; 4370da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4371da1ce067SMiklos Szeredi error = -ENOENT; 4372da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4373da1ce067SMiklos Szeredi goto exit5; 4374da1ce067SMiklos Szeredi 4375da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4376da1ce067SMiklos Szeredi error = -ENOTDIR; 4377f5beed75SAl Viro if (new_last.name[new_last.len]) 4378da1ce067SMiklos Szeredi goto exit5; 4379da1ce067SMiklos Szeredi } 4380da1ce067SMiklos Szeredi } 43810a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43820a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43830a7c3937SMiklos Szeredi error = -ENOTDIR; 4384f5beed75SAl Viro if (old_last.name[old_last.len]) 43850a7c3937SMiklos Szeredi goto exit5; 4386f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43870a7c3937SMiklos Szeredi goto exit5; 43880a7c3937SMiklos Szeredi } 43890a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43900a7c3937SMiklos Szeredi error = -EINVAL; 43910a7c3937SMiklos Szeredi if (old_dentry == trap) 43920a7c3937SMiklos Szeredi goto exit5; 43931da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4394da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43951da177e4SLinus Torvalds error = -ENOTEMPTY; 43961da177e4SLinus Torvalds if (new_dentry == trap) 43971da177e4SLinus Torvalds goto exit5; 43981da177e4SLinus Torvalds 4399f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4400f5beed75SAl Viro &new_path, new_dentry, flags); 4401be6d3e56SKentaro Takeda if (error) 4402c30dabfeSJan Kara goto exit5; 4403f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4404f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4405520c8b16SMiklos Szeredi &delegated_inode, flags); 44061da177e4SLinus Torvalds exit5: 44071da177e4SLinus Torvalds dput(new_dentry); 44081da177e4SLinus Torvalds exit4: 44091da177e4SLinus Torvalds dput(old_dentry); 44101da177e4SLinus Torvalds exit3: 4411f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44128e6d782cSJ. Bruce Fields if (delegated_inode) { 44138e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44148e6d782cSJ. Bruce Fields if (!error) 44158e6d782cSJ. Bruce Fields goto retry_deleg; 44168e6d782cSJ. Bruce Fields } 4417f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44181da177e4SLinus Torvalds exit2: 4419c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4420c6a94284SJeff Layton should_retry = true; 4421f5beed75SAl Viro path_put(&new_path); 44222ad94ae6SAl Viro putname(to); 44231da177e4SLinus Torvalds exit1: 4424f5beed75SAl Viro path_put(&old_path); 44251da177e4SLinus Torvalds putname(from); 4426c6a94284SJeff Layton if (should_retry) { 4427c6a94284SJeff Layton should_retry = false; 4428c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4429c6a94284SJeff Layton goto retry; 4430c6a94284SJeff Layton } 44312ad94ae6SAl Viro exit: 44321da177e4SLinus Torvalds return error; 44331da177e4SLinus Torvalds } 44341da177e4SLinus Torvalds 4435520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4436520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4437520c8b16SMiklos Szeredi { 4438520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4439520c8b16SMiklos Szeredi } 4440520c8b16SMiklos Szeredi 4441a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44425590ff0dSUlrich Drepper { 4443520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44445590ff0dSUlrich Drepper } 44455590ff0dSUlrich Drepper 4446787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4447787fb6bcSMiklos Szeredi { 4448787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4449787fb6bcSMiklos Szeredi if (error) 4450787fb6bcSMiklos Szeredi return error; 4451787fb6bcSMiklos Szeredi 4452787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4453787fb6bcSMiklos Szeredi return -EPERM; 4454787fb6bcSMiklos Szeredi 4455787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4456787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4457787fb6bcSMiklos Szeredi } 4458787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4459787fb6bcSMiklos Szeredi 44605d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44611da177e4SLinus Torvalds { 44625d826c84SAl Viro int len = PTR_ERR(link); 44631da177e4SLinus Torvalds if (IS_ERR(link)) 44641da177e4SLinus Torvalds goto out; 44651da177e4SLinus Torvalds 44661da177e4SLinus Torvalds len = strlen(link); 44671da177e4SLinus Torvalds if (len > (unsigned) buflen) 44681da177e4SLinus Torvalds len = buflen; 44691da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44701da177e4SLinus Torvalds len = -EFAULT; 44711da177e4SLinus Torvalds out: 44721da177e4SLinus Torvalds return len; 44731da177e4SLinus Torvalds } 44745d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44751da177e4SLinus Torvalds 44761da177e4SLinus Torvalds /* 44771da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44781da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44791da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44801da177e4SLinus Torvalds */ 44811da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44821da177e4SLinus Torvalds { 4483cc314eefSLinus Torvalds void *cookie; 4484d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4485694a1764SMarcin Slusarz int res; 4486cc314eefSLinus Torvalds 4487d4dee48bSAl Viro if (!link) { 4488d4dee48bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); 4489680baacbSAl Viro if (IS_ERR(link)) 4490680baacbSAl Viro return PTR_ERR(link); 4491d4dee48bSAl Viro } 4492680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4493680baacbSAl Viro if (cookie && dentry->d_inode->i_op->put_link) 4494680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4495694a1764SMarcin Slusarz return res; 44961da177e4SLinus Torvalds } 44974d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44981da177e4SLinus Torvalds 44991da177e4SLinus Torvalds /* get the link contents into pagecache */ 45001da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45011da177e4SLinus Torvalds { 4502ebd09abbSDuane Griffin char *kaddr; 45031da177e4SLinus Torvalds struct page *page; 45041da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4505090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45061da177e4SLinus Torvalds if (IS_ERR(page)) 45076fe6900eSNick Piggin return (char*)page; 45081da177e4SLinus Torvalds *ppage = page; 4509ebd09abbSDuane Griffin kaddr = kmap(page); 4510ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4511ebd09abbSDuane Griffin return kaddr; 45121da177e4SLinus Torvalds } 45131da177e4SLinus Torvalds 45141da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45151da177e4SLinus Torvalds { 45161da177e4SLinus Torvalds struct page *page = NULL; 45175d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45181da177e4SLinus Torvalds if (page) { 45191da177e4SLinus Torvalds kunmap(page); 45201da177e4SLinus Torvalds page_cache_release(page); 45211da177e4SLinus Torvalds } 45221da177e4SLinus Torvalds return res; 45231da177e4SLinus Torvalds } 45244d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45251da177e4SLinus Torvalds 4526680baacbSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) 45271da177e4SLinus Torvalds { 4528cc314eefSLinus Torvalds struct page *page = NULL; 4529680baacbSAl Viro char *res = page_getlink(dentry, &page); 4530680baacbSAl Viro if (!IS_ERR(res)) 4531680baacbSAl Viro *cookie = page; 4532680baacbSAl Viro return res; 45331da177e4SLinus Torvalds } 45344d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45351da177e4SLinus Torvalds 4536680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45371da177e4SLinus Torvalds { 4538cc314eefSLinus Torvalds struct page *page = cookie; 45391da177e4SLinus Torvalds kunmap(page); 45401da177e4SLinus Torvalds page_cache_release(page); 45411da177e4SLinus Torvalds } 45424d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45431da177e4SLinus Torvalds 454454566b2cSNick Piggin /* 454554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 454654566b2cSNick Piggin */ 454754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45481da177e4SLinus Torvalds { 45491da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45500adb25d2SKirill Korotaev struct page *page; 4551afddba49SNick Piggin void *fsdata; 4552beb497abSDmitriy Monakhov int err; 45531da177e4SLinus Torvalds char *kaddr; 455454566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 455554566b2cSNick Piggin if (nofs) 455654566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45571da177e4SLinus Torvalds 45587e53cac4SNeilBrown retry: 4559afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 456054566b2cSNick Piggin flags, &page, &fsdata); 45611da177e4SLinus Torvalds if (err) 4562afddba49SNick Piggin goto fail; 4563afddba49SNick Piggin 4564e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45651da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4566e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4567afddba49SNick Piggin 4568afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4569afddba49SNick Piggin page, fsdata); 45701da177e4SLinus Torvalds if (err < 0) 45711da177e4SLinus Torvalds goto fail; 4572afddba49SNick Piggin if (err < len-1) 4573afddba49SNick Piggin goto retry; 4574afddba49SNick Piggin 45751da177e4SLinus Torvalds mark_inode_dirty(inode); 45761da177e4SLinus Torvalds return 0; 45771da177e4SLinus Torvalds fail: 45781da177e4SLinus Torvalds return err; 45791da177e4SLinus Torvalds } 45804d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45811da177e4SLinus Torvalds 45820adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45830adb25d2SKirill Korotaev { 45840adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 458554566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45860adb25d2SKirill Korotaev } 45874d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45880adb25d2SKirill Korotaev 458992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45901da177e4SLinus Torvalds .readlink = generic_readlink, 45911da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45921da177e4SLinus Torvalds .put_link = page_put_link, 45931da177e4SLinus Torvalds }; 45941da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4595