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; 1121a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 11221da177e4SLinus Torvalds } 11231da177e4SLinus Torvalds 1124cc53ce53SDavid Howells int follow_down_one(struct path *path) 11251da177e4SLinus Torvalds { 11261da177e4SLinus Torvalds struct vfsmount *mounted; 11271da177e4SLinus Torvalds 11281c755af4SAl Viro mounted = lookup_mnt(path); 11291da177e4SLinus Torvalds if (mounted) { 11309393bd07SAl Viro dput(path->dentry); 11319393bd07SAl Viro mntput(path->mnt); 11329393bd07SAl Viro path->mnt = mounted; 11339393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11341da177e4SLinus Torvalds return 1; 11351da177e4SLinus Torvalds } 11361da177e4SLinus Torvalds return 0; 11371da177e4SLinus Torvalds } 11384d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11391da177e4SLinus Torvalds 1140b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 114162a7375eSIan Kent { 1142b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1143b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 114462a7375eSIan Kent } 114562a7375eSIan Kent 11469875cf80SDavid Howells /* 1147287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1148287548e4SAl Viro * we meet a managed dentry that would need blocking. 11499875cf80SDavid Howells */ 11509875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1151287548e4SAl Viro struct inode **inode) 11529875cf80SDavid Howells { 115362a7375eSIan Kent for (;;) { 1154c7105365SAl Viro struct mount *mounted; 115562a7375eSIan Kent /* 115662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 115762a7375eSIan Kent * that wants to block transit. 115862a7375eSIan Kent */ 1159b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1160b8faf035SNeilBrown case -ECHILD: 1161b8faf035SNeilBrown default: 1162ab90911fSDavid Howells return false; 1163b8faf035SNeilBrown case -EISDIR: 1164b8faf035SNeilBrown return true; 1165b8faf035SNeilBrown case 0: 1166b8faf035SNeilBrown break; 1167b8faf035SNeilBrown } 116862a7375eSIan Kent 116962a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1170b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 117162a7375eSIan Kent 1172474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11739875cf80SDavid Howells if (!mounted) 11749875cf80SDavid Howells break; 1175c7105365SAl Viro path->mnt = &mounted->mnt; 1176c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1177a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11789875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 117959430262SLinus Torvalds /* 118059430262SLinus Torvalds * Update the inode too. We don't need to re-check the 118159430262SLinus Torvalds * dentry sequence number here after this d_inode read, 118259430262SLinus Torvalds * because a mount-point is always pinned. 118359430262SLinus Torvalds */ 118459430262SLinus Torvalds *inode = path->dentry->d_inode; 11859875cf80SDavid Howells } 1186f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1187b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1188287548e4SAl Viro } 1189287548e4SAl Viro 119031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 119131e6b01fSNick Piggin { 11924023bfc9SAl Viro struct inode *inode = nd->inode; 11937bd88377SAl Viro if (!nd->root.mnt) 119431e6b01fSNick Piggin set_root_rcu(nd); 119531e6b01fSNick Piggin 119631e6b01fSNick Piggin while (1) { 119731e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 119831e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 119931e6b01fSNick Piggin break; 120031e6b01fSNick Piggin } 120131e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 120231e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 120331e6b01fSNick Piggin struct dentry *parent = old->d_parent; 120431e6b01fSNick Piggin unsigned seq; 120531e6b01fSNick Piggin 12064023bfc9SAl Viro inode = parent->d_inode; 120731e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 120831e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1209ef7562d5SAl Viro goto failed; 121031e6b01fSNick Piggin nd->path.dentry = parent; 121131e6b01fSNick Piggin nd->seq = seq; 121231e6b01fSNick Piggin break; 121331e6b01fSNick Piggin } 121431e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 121531e6b01fSNick Piggin break; 12164023bfc9SAl Viro inode = nd->path.dentry->d_inode; 121731e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 121831e6b01fSNick Piggin } 1219b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1220b37199e6SAl Viro struct mount *mounted; 1221b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1222b37199e6SAl Viro if (!mounted) 1223b37199e6SAl Viro break; 1224b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1225b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12264023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1227b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1228f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1229b37199e6SAl Viro goto failed; 1230b37199e6SAl Viro } 12314023bfc9SAl Viro nd->inode = inode; 123231e6b01fSNick Piggin return 0; 1233ef7562d5SAl Viro 1234ef7562d5SAl Viro failed: 1235ef7562d5SAl Viro return -ECHILD; 123631e6b01fSNick Piggin } 123731e6b01fSNick Piggin 12389875cf80SDavid Howells /* 1239cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1240cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1241cc53ce53SDavid Howells * caller is permitted to proceed or not. 1242cc53ce53SDavid Howells */ 12437cc90cc3SAl Viro int follow_down(struct path *path) 1244cc53ce53SDavid Howells { 1245cc53ce53SDavid Howells unsigned managed; 1246cc53ce53SDavid Howells int ret; 1247cc53ce53SDavid Howells 1248cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1249cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1250cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1251cc53ce53SDavid Howells * being held. 1252cc53ce53SDavid Howells * 1253cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1254cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1255cc53ce53SDavid Howells * other than its daemon the right to mount on its 1256cc53ce53SDavid Howells * superstructure. 1257cc53ce53SDavid Howells * 1258cc53ce53SDavid Howells * The filesystem may sleep at this point. 1259cc53ce53SDavid Howells */ 1260cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1261cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1262cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1263ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12641aed3e42SAl Viro path->dentry, false); 1265cc53ce53SDavid Howells if (ret < 0) 1266cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1267cc53ce53SDavid Howells } 1268cc53ce53SDavid Howells 1269cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1270cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1271cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1272cc53ce53SDavid Howells if (!mounted) 1273cc53ce53SDavid Howells break; 1274cc53ce53SDavid Howells dput(path->dentry); 1275cc53ce53SDavid Howells mntput(path->mnt); 1276cc53ce53SDavid Howells path->mnt = mounted; 1277cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1278cc53ce53SDavid Howells continue; 1279cc53ce53SDavid Howells } 1280cc53ce53SDavid Howells 1281cc53ce53SDavid Howells /* Don't handle automount points here */ 1282cc53ce53SDavid Howells break; 1283cc53ce53SDavid Howells } 1284cc53ce53SDavid Howells return 0; 1285cc53ce53SDavid Howells } 12864d359507SAl Viro EXPORT_SYMBOL(follow_down); 1287cc53ce53SDavid Howells 1288cc53ce53SDavid Howells /* 12899875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12909875cf80SDavid Howells */ 12919875cf80SDavid Howells static void follow_mount(struct path *path) 12929875cf80SDavid Howells { 12939875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12949875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12959875cf80SDavid Howells if (!mounted) 12969875cf80SDavid Howells break; 12979875cf80SDavid Howells dput(path->dentry); 12989875cf80SDavid Howells mntput(path->mnt); 12999875cf80SDavid Howells path->mnt = mounted; 13009875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13019875cf80SDavid Howells } 13029875cf80SDavid Howells } 13039875cf80SDavid Howells 130431e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 13051da177e4SLinus Torvalds { 13067bd88377SAl Viro if (!nd->root.mnt) 13072a737871SAl Viro set_root(nd); 1308e518ddb7SAndreas Mohr 13091da177e4SLinus Torvalds while(1) { 13104ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13111da177e4SLinus Torvalds 13122a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13132a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13141da177e4SLinus Torvalds break; 13151da177e4SLinus Torvalds } 13164ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13173088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13183088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13191da177e4SLinus Torvalds dput(old); 13201da177e4SLinus Torvalds break; 13211da177e4SLinus Torvalds } 13223088dd70SAl Viro if (!follow_up(&nd->path)) 13231da177e4SLinus Torvalds break; 13241da177e4SLinus Torvalds } 132579ed0226SAl Viro follow_mount(&nd->path); 132631e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13271da177e4SLinus Torvalds } 13281da177e4SLinus Torvalds 13291da177e4SLinus Torvalds /* 1330bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1331bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1332bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1333bad61189SMiklos Szeredi * 1334bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1335baa03890SNick Piggin */ 1336bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1337201f956eSAl Viro unsigned int flags, bool *need_lookup) 1338baa03890SNick Piggin { 1339baa03890SNick Piggin struct dentry *dentry; 1340bad61189SMiklos Szeredi int error; 1341baa03890SNick Piggin 1342bad61189SMiklos Szeredi *need_lookup = false; 1343bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1344bad61189SMiklos Szeredi if (dentry) { 134539e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1346201f956eSAl Viro error = d_revalidate(dentry, flags); 1347bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1348bad61189SMiklos Szeredi if (error < 0) { 1349bad61189SMiklos Szeredi dput(dentry); 1350bad61189SMiklos Szeredi return ERR_PTR(error); 13515542aa2fSEric W. Biederman } else { 13525542aa2fSEric W. Biederman d_invalidate(dentry); 1353bad61189SMiklos Szeredi dput(dentry); 1354bad61189SMiklos Szeredi dentry = NULL; 1355bad61189SMiklos Szeredi } 1356bad61189SMiklos Szeredi } 1357bad61189SMiklos Szeredi } 1358bad61189SMiklos Szeredi } 1359baa03890SNick Piggin 1360bad61189SMiklos Szeredi if (!dentry) { 1361bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1362baa03890SNick Piggin if (unlikely(!dentry)) 1363baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1364baa03890SNick Piggin 1365bad61189SMiklos Szeredi *need_lookup = true; 1366baa03890SNick Piggin } 1367baa03890SNick Piggin return dentry; 1368baa03890SNick Piggin } 1369baa03890SNick Piggin 1370baa03890SNick Piggin /* 137113a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 137213a2c3beSJ. Bruce Fields * unhashed. 1373bad61189SMiklos Szeredi * 1374bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 137544396f4bSJosef Bacik */ 1376bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 137772bd866aSAl Viro unsigned int flags) 137844396f4bSJosef Bacik { 137944396f4bSJosef Bacik struct dentry *old; 138044396f4bSJosef Bacik 138144396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1382bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1383e188dc02SMiklos Szeredi dput(dentry); 138444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1385e188dc02SMiklos Szeredi } 138644396f4bSJosef Bacik 138772bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 138844396f4bSJosef Bacik if (unlikely(old)) { 138944396f4bSJosef Bacik dput(dentry); 139044396f4bSJosef Bacik dentry = old; 139144396f4bSJosef Bacik } 139244396f4bSJosef Bacik return dentry; 139344396f4bSJosef Bacik } 139444396f4bSJosef Bacik 1395a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 139672bd866aSAl Viro struct dentry *base, unsigned int flags) 1397a3255546SAl Viro { 1398bad61189SMiklos Szeredi bool need_lookup; 1399a3255546SAl Viro struct dentry *dentry; 1400a3255546SAl Viro 140172bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1402bad61189SMiklos Szeredi if (!need_lookup) 1403a3255546SAl Viro return dentry; 1404bad61189SMiklos Szeredi 140572bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1406a3255546SAl Viro } 1407a3255546SAl Viro 140844396f4bSJosef Bacik /* 14091da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14101da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14111da177e4SLinus Torvalds * It _is_ time-critical. 14121da177e4SLinus Torvalds */ 1413e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 141431e6b01fSNick Piggin struct path *path, struct inode **inode) 14151da177e4SLinus Torvalds { 14164ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 141731e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14185a18fff2SAl Viro int need_reval = 1; 14195a18fff2SAl Viro int status = 1; 14209875cf80SDavid Howells int err; 14219875cf80SDavid Howells 14223cac260aSAl Viro /* 1423b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1424b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1425b04f784eSNick Piggin * do the non-racy lookup, below. 1426b04f784eSNick Piggin */ 142731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 142831e6b01fSNick Piggin unsigned seq; 1429766c4cbfSAl Viro bool negative; 1430da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14315a18fff2SAl Viro if (!dentry) 14325a18fff2SAl Viro goto unlazy; 14335a18fff2SAl Viro 143412f8ad4bSLinus Torvalds /* 143512f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 143612f8ad4bSLinus Torvalds * the dentry name information from lookup. 143712f8ad4bSLinus Torvalds */ 143812f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1439766c4cbfSAl Viro negative = d_is_negative(dentry); 144012f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 144112f8ad4bSLinus Torvalds return -ECHILD; 1442766c4cbfSAl Viro if (negative) 1443766c4cbfSAl Viro return -ENOENT; 144412f8ad4bSLinus Torvalds 144512f8ad4bSLinus Torvalds /* 144612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 144712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 144812f8ad4bSLinus Torvalds * 144912f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 145012f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 145112f8ad4bSLinus Torvalds */ 145231e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 145331e6b01fSNick Piggin return -ECHILD; 145431e6b01fSNick Piggin nd->seq = seq; 14555a18fff2SAl Viro 145624643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14574ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14585a18fff2SAl Viro if (unlikely(status <= 0)) { 14595a18fff2SAl Viro if (status != -ECHILD) 14605a18fff2SAl Viro need_reval = 0; 14615a18fff2SAl Viro goto unlazy; 14625a18fff2SAl Viro } 146324643087SAl Viro } 146431e6b01fSNick Piggin path->mnt = mnt; 146531e6b01fSNick Piggin path->dentry = dentry; 1466b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14679875cf80SDavid Howells return 0; 14685a18fff2SAl Viro unlazy: 146919660af7SAl Viro if (unlazy_walk(nd, dentry)) 14705a18fff2SAl Viro return -ECHILD; 14715a18fff2SAl Viro } else { 1472e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 147324643087SAl Viro } 14745a18fff2SAl Viro 147581e6f520SAl Viro if (unlikely(!dentry)) 147681e6f520SAl Viro goto need_lookup; 14775a18fff2SAl Viro 14785a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14794ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14805a18fff2SAl Viro if (unlikely(status <= 0)) { 14815a18fff2SAl Viro if (status < 0) { 14825a18fff2SAl Viro dput(dentry); 14835a18fff2SAl Viro return status; 14845a18fff2SAl Viro } 14855542aa2fSEric W. Biederman d_invalidate(dentry); 14865a18fff2SAl Viro dput(dentry); 148781e6f520SAl Viro goto need_lookup; 14885a18fff2SAl Viro } 1489697f514dSMiklos Szeredi 1490766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1491766c4cbfSAl Viro dput(dentry); 1492766c4cbfSAl Viro return -ENOENT; 1493766c4cbfSAl Viro } 14941da177e4SLinus Torvalds path->mnt = mnt; 14951da177e4SLinus Torvalds path->dentry = dentry; 1496756daf26SNeilBrown err = follow_managed(path, nd); 149789312214SIan Kent if (unlikely(err < 0)) { 149889312214SIan Kent path_put_conditional(path, nd); 14999875cf80SDavid Howells return err; 150089312214SIan Kent } 1501a3fbbde7SAl Viro if (err) 1502a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 150331e6b01fSNick Piggin *inode = path->dentry->d_inode; 15041da177e4SLinus Torvalds return 0; 150581e6f520SAl Viro 150681e6f520SAl Viro need_lookup: 1507697f514dSMiklos Szeredi return 1; 1508697f514dSMiklos Szeredi } 1509697f514dSMiklos Szeredi 1510697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1511cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1512697f514dSMiklos Szeredi { 1513697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1514697f514dSMiklos Szeredi int err; 1515697f514dSMiklos Szeredi 1516697f514dSMiklos Szeredi parent = nd->path.dentry; 151781e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 151881e6f520SAl Viro 151981e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1520cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 152181e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 152281e6f520SAl Viro if (IS_ERR(dentry)) 152381e6f520SAl Viro return PTR_ERR(dentry); 1524697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1525697f514dSMiklos Szeredi path->dentry = dentry; 1526756daf26SNeilBrown err = follow_managed(path, nd); 1527697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1528697f514dSMiklos Szeredi path_put_conditional(path, nd); 1529697f514dSMiklos Szeredi return err; 1530697f514dSMiklos Szeredi } 1531697f514dSMiklos Szeredi if (err) 1532697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1533697f514dSMiklos Szeredi return 0; 15341da177e4SLinus Torvalds } 15351da177e4SLinus Torvalds 153652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 153752094c8aSAl Viro { 153852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15394ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 154052094c8aSAl Viro if (err != -ECHILD) 154152094c8aSAl Viro return err; 154219660af7SAl Viro if (unlazy_walk(nd, NULL)) 154352094c8aSAl Viro return -ECHILD; 154452094c8aSAl Viro } 15454ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 154652094c8aSAl Viro } 154752094c8aSAl Viro 15489856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15499856fa1bSAl Viro { 15509856fa1bSAl Viro if (type == LAST_DOTDOT) { 15519856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 155270291aecSAl Viro return follow_dotdot_rcu(nd); 15539856fa1bSAl Viro } else 15549856fa1bSAl Viro follow_dotdot(nd); 15559856fa1bSAl Viro } 15569856fa1bSAl Viro return 0; 15579856fa1bSAl Viro } 15589856fa1bSAl Viro 1559951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1560951361f9SAl Viro { 1561951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1562951361f9SAl Viro path_put(&nd->path); 1563951361f9SAl Viro } else { 1564951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15655b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1566951361f9SAl Viro nd->root.mnt = NULL; 15678b61e74fSAl Viro rcu_read_unlock(); 1568951361f9SAl Viro } 156915439726SAl Viro while (unlikely(nd->depth)) 157015439726SAl Viro put_link(nd); 1571951361f9SAl Viro } 1572951361f9SAl Viro 1573d63ff28fSAl Viro static int pick_link(struct nameidata *nd, struct path *link) 1574d63ff28fSAl Viro { 1575626de996SAl Viro int error; 1576756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1577626de996SAl Viro path_to_nameidata(link, nd); 1578626de996SAl Viro return -ELOOP; 1579626de996SAl Viro } 1580d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1581d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1582d63ff28fSAl Viro unlazy_walk(nd, link->dentry))) { 1583d63ff28fSAl Viro return -ECHILD; 1584d63ff28fSAl Viro } 1585d63ff28fSAl Viro } 1586626de996SAl Viro error = nd_alloc_stack(nd); 1587626de996SAl Viro if (unlikely(error)) { 1588626de996SAl Viro path_to_nameidata(link, nd); 1589626de996SAl Viro return error; 1590626de996SAl Viro } 1591626de996SAl Viro 1592d63ff28fSAl Viro nd->link = *link; 1593d63ff28fSAl Viro return 1; 1594d63ff28fSAl Viro } 1595d63ff28fSAl Viro 15963ddcd056SLinus Torvalds /* 15973ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15983ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15993ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16003ddcd056SLinus Torvalds * for the common case. 16013ddcd056SLinus Torvalds */ 1602d63ff28fSAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow) 16033ddcd056SLinus Torvalds { 1604d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1605d63ff28fSAl Viro return 0; 1606d63ff28fSAl Viro if (!follow) 1607d63ff28fSAl Viro return 0; 1608d63ff28fSAl Viro return pick_link(nd, link); 16093ddcd056SLinus Torvalds } 16103ddcd056SLinus Torvalds 16114693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16124693a547SAl Viro 16134693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1614ce57dfc1SAl Viro { 1615caa85634SAl Viro struct path path; 1616ce57dfc1SAl Viro struct inode *inode; 1617ce57dfc1SAl Viro int err; 1618ce57dfc1SAl Viro /* 1619ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1620ce57dfc1SAl Viro * to be able to know about the current root directory and 1621ce57dfc1SAl Viro * parent relationships. 1622ce57dfc1SAl Viro */ 16234693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16244693a547SAl Viro err = handle_dots(nd, nd->last_type); 16254693a547SAl Viro if (flags & WALK_PUT) 16264693a547SAl Viro put_link(nd); 16274693a547SAl Viro return err; 16284693a547SAl Viro } 1629caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1630ce57dfc1SAl Viro if (unlikely(err)) { 1631697f514dSMiklos Szeredi if (err < 0) 1632f0a9ba70SAl Viro return err; 1633697f514dSMiklos Szeredi 1634caa85634SAl Viro err = lookup_slow(nd, &path); 1635697f514dSMiklos Szeredi if (err < 0) 1636f0a9ba70SAl Viro return err; 1637697f514dSMiklos Szeredi 1638caa85634SAl Viro inode = path.dentry->d_inode; 1639697f514dSMiklos Szeredi err = -ENOENT; 1640caa85634SAl Viro if (d_is_negative(path.dentry)) 1641697f514dSMiklos Szeredi goto out_path_put; 1642766c4cbfSAl Viro } 1643697f514dSMiklos Szeredi 16444693a547SAl Viro if (flags & WALK_PUT) 16454693a547SAl Viro put_link(nd); 1646d63ff28fSAl Viro err = should_follow_link(nd, &path, flags & WALK_GET); 1647d63ff28fSAl Viro if (unlikely(err)) 1648d63ff28fSAl Viro return err; 1649caa85634SAl Viro path_to_nameidata(&path, nd); 1650ce57dfc1SAl Viro nd->inode = inode; 1651ce57dfc1SAl Viro return 0; 1652697f514dSMiklos Szeredi 1653697f514dSMiklos Szeredi out_path_put: 1654caa85634SAl Viro path_to_nameidata(&path, nd); 1655697f514dSMiklos Szeredi return err; 1656ce57dfc1SAl Viro } 1657ce57dfc1SAl Viro 16581da177e4SLinus Torvalds /* 1659bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1660bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1661bfcfaa77SLinus Torvalds * 1662bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1663bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1664bfcfaa77SLinus Torvalds * fast. 1665bfcfaa77SLinus Torvalds * 1666bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1667bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1668bfcfaa77SLinus Torvalds * crossing operation. 1669bfcfaa77SLinus Torvalds * 1670bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1671bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1672bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1673bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1674bfcfaa77SLinus Torvalds */ 1675bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1676bfcfaa77SLinus Torvalds 1677f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1678bfcfaa77SLinus Torvalds 1679f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1680bfcfaa77SLinus Torvalds 1681bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1682bfcfaa77SLinus Torvalds { 168399d263d4SLinus Torvalds return hash_64(hash, 32); 1684bfcfaa77SLinus Torvalds } 1685bfcfaa77SLinus Torvalds 1686bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1687bfcfaa77SLinus Torvalds 1688bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1689bfcfaa77SLinus Torvalds 1690bfcfaa77SLinus Torvalds #endif 1691bfcfaa77SLinus Torvalds 1692bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1693bfcfaa77SLinus Torvalds { 1694bfcfaa77SLinus Torvalds unsigned long a, mask; 1695bfcfaa77SLinus Torvalds unsigned long hash = 0; 1696bfcfaa77SLinus Torvalds 1697bfcfaa77SLinus Torvalds for (;;) { 1698e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1699bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1700bfcfaa77SLinus Torvalds break; 1701bfcfaa77SLinus Torvalds hash += a; 1702f132c5beSAl Viro hash *= 9; 1703bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1704bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1705bfcfaa77SLinus Torvalds if (!len) 1706bfcfaa77SLinus Torvalds goto done; 1707bfcfaa77SLinus Torvalds } 1708a5c21dceSWill Deacon mask = bytemask_from_count(len); 1709bfcfaa77SLinus Torvalds hash += mask & a; 1710bfcfaa77SLinus Torvalds done: 1711bfcfaa77SLinus Torvalds return fold_hash(hash); 1712bfcfaa77SLinus Torvalds } 1713bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1714bfcfaa77SLinus Torvalds 1715bfcfaa77SLinus Torvalds /* 1716bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1717d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1718bfcfaa77SLinus Torvalds */ 1719d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1720bfcfaa77SLinus Torvalds { 172136126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 172236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1723bfcfaa77SLinus Torvalds 1724bfcfaa77SLinus Torvalds hash = a = 0; 1725bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1726bfcfaa77SLinus Torvalds do { 1727bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1728bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1729e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 173036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 173136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1732bfcfaa77SLinus Torvalds 173336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 173436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 173536126f8fSLinus Torvalds 173636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 173736126f8fSLinus Torvalds 173836126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17399226b5b4SLinus Torvalds len += find_zero(mask); 1740d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1741bfcfaa77SLinus Torvalds } 1742bfcfaa77SLinus Torvalds 1743bfcfaa77SLinus Torvalds #else 1744bfcfaa77SLinus Torvalds 17450145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17460145acc2SLinus Torvalds { 17470145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17480145acc2SLinus Torvalds while (len--) 17490145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17500145acc2SLinus Torvalds return end_name_hash(hash); 17510145acc2SLinus Torvalds } 1752ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17530145acc2SLinus Torvalds 17543ddcd056SLinus Torvalds /* 1755200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1756200e9ef7SLinus Torvalds * one character. 1757200e9ef7SLinus Torvalds */ 1758d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1759200e9ef7SLinus Torvalds { 1760200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1761200e9ef7SLinus Torvalds unsigned long len = 0, c; 1762200e9ef7SLinus Torvalds 1763200e9ef7SLinus Torvalds c = (unsigned char)*name; 1764200e9ef7SLinus Torvalds do { 1765200e9ef7SLinus Torvalds len++; 1766200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1767200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1768200e9ef7SLinus Torvalds } while (c && c != '/'); 1769d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1770200e9ef7SLinus Torvalds } 1771200e9ef7SLinus Torvalds 1772bfcfaa77SLinus Torvalds #endif 1773bfcfaa77SLinus Torvalds 1774200e9ef7SLinus Torvalds /* 17751da177e4SLinus Torvalds * Name resolution. 1776ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1777ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17781da177e4SLinus Torvalds * 1779ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1780ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17811da177e4SLinus Torvalds */ 17826de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17831da177e4SLinus Torvalds { 17841da177e4SLinus Torvalds int err; 17851da177e4SLinus Torvalds 17861da177e4SLinus Torvalds while (*name=='/') 17871da177e4SLinus Torvalds name++; 17881da177e4SLinus Torvalds if (!*name) 17899e18f10aSAl Viro return 0; 17901da177e4SLinus Torvalds 17911da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17921da177e4SLinus Torvalds for(;;) { 1793d6bb3e90SLinus Torvalds u64 hash_len; 1794fe479a58SAl Viro int type; 17951da177e4SLinus Torvalds 179652094c8aSAl Viro err = may_lookup(nd); 17971da177e4SLinus Torvalds if (err) 17981da177e4SLinus Torvalds break; 17991da177e4SLinus Torvalds 1800d6bb3e90SLinus Torvalds hash_len = hash_name(name); 18011da177e4SLinus Torvalds 1802fe479a58SAl Viro type = LAST_NORM; 1803d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1804fe479a58SAl Viro case 2: 1805200e9ef7SLinus Torvalds if (name[1] == '.') { 1806fe479a58SAl Viro type = LAST_DOTDOT; 180716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 180816c2cd71SAl Viro } 1809fe479a58SAl Viro break; 1810fe479a58SAl Viro case 1: 1811fe479a58SAl Viro type = LAST_DOT; 1812fe479a58SAl Viro } 18135a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18145a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 181516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18165a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1817a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1818da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18195a202bcdSAl Viro if (err < 0) 18205a202bcdSAl Viro break; 1821d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1822d6bb3e90SLinus Torvalds name = this.name; 18235a202bcdSAl Viro } 18245a202bcdSAl Viro } 1825fe479a58SAl Viro 1826d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1827d6bb3e90SLinus Torvalds nd->last.name = name; 18285f4a6a69SAl Viro nd->last_type = type; 18295f4a6a69SAl Viro 1830d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1831d6bb3e90SLinus Torvalds if (!*name) 1832bdf6cbf1SAl Viro goto OK; 1833200e9ef7SLinus Torvalds /* 1834200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1835200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1836200e9ef7SLinus Torvalds */ 1837200e9ef7SLinus Torvalds do { 1838d6bb3e90SLinus Torvalds name++; 1839d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18408620c238SAl Viro if (unlikely(!*name)) { 18418620c238SAl Viro OK: 18428620c238SAl Viro /* called from path_init(), done */ 18438620c238SAl Viro if (!nd->depth) 18448620c238SAl Viro return 0; 18458620c238SAl Viro name = nd->stack[nd->depth - 1].name; 18468620c238SAl Viro /* called from trailing_symlink(), done */ 18478620c238SAl Viro if (!name) 18488620c238SAl Viro return 0; 18498620c238SAl Viro /* last component of nested symlink */ 18504693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18518620c238SAl Viro } else { 18524693a547SAl Viro err = walk_component(nd, WALK_GET); 18538620c238SAl Viro } 1854ce57dfc1SAl Viro if (err < 0) 1855f0a9ba70SAl Viro break; 1856fe479a58SAl Viro 1857ce57dfc1SAl Viro if (err) { 1858626de996SAl Viro const char *s = get_link(nd); 18595a460275SAl Viro 1860172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1861172a39a0SAl Viro err = PTR_ERR(s); 18621bc4b813SAl Viro break; 1863172a39a0SAl Viro } 1864172a39a0SAl Viro err = 0; 186512b09578SAl Viro if (unlikely(!s)) { 186612b09578SAl Viro /* jumped */ 1867b9ff4429SAl Viro put_link(nd); 186812b09578SAl Viro } else { 1869172a39a0SAl Viro if (*s == '/') { 1870172a39a0SAl Viro if (!nd->root.mnt) 1871172a39a0SAl Viro set_root(nd); 1872172a39a0SAl Viro path_put(&nd->path); 1873172a39a0SAl Viro nd->path = nd->root; 1874172a39a0SAl Viro path_get(&nd->root); 1875172a39a0SAl Viro nd->flags |= LOOKUP_JUMPED; 18769e18f10aSAl Viro while (unlikely(*++s == '/')) 18779e18f10aSAl Viro ; 1878172a39a0SAl Viro } 1879172a39a0SAl Viro nd->inode = nd->path.dentry->d_inode; 1880071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 18819e18f10aSAl Viro if (!*s) 18829e18f10aSAl Viro goto OK; 188332cd7468SAl Viro name = s; 18849e18f10aSAl Viro continue; 188548c8b0c5SAl Viro } 188631e6b01fSNick Piggin } 188744b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18883ddcd056SLinus Torvalds err = -ENOTDIR; 18893ddcd056SLinus Torvalds break; 18905f4a6a69SAl Viro } 1891ce57dfc1SAl Viro } 1892951361f9SAl Viro terminate_walk(nd); 18931da177e4SLinus Torvalds return err; 189407681481SAl Viro } 18951da177e4SLinus Torvalds 18966e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18975e53084dSAl Viro struct nameidata *nd) 189831e6b01fSNick Piggin { 189931e6b01fSNick Piggin int retval = 0; 1900fd2f7cb5SAl Viro const char *s = name->name; 190131e6b01fSNick Piggin 190231e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1903980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 190431e6b01fSNick Piggin nd->depth = 0; 19055e53084dSAl Viro nd->base = NULL; 19065b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1907b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1908b18825a7SDavid Howells struct inode *inode = root->d_inode; 1909fd2f7cb5SAl Viro if (*s) { 191044b1d530SMiklos Szeredi if (!d_can_lookup(root)) 19115b6ca027SAl Viro return -ENOTDIR; 19125b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19135b6ca027SAl Viro if (retval) 19145b6ca027SAl Viro return retval; 191573d049a4SAl Viro } 19165b6ca027SAl Viro nd->path = nd->root; 19175b6ca027SAl Viro nd->inode = inode; 19185b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19198b61e74fSAl Viro rcu_read_lock(); 19205b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 192148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19225b6ca027SAl Viro } else { 19235b6ca027SAl Viro path_get(&nd->path); 19245b6ca027SAl Viro } 1925d465887fSAl Viro goto done; 19265b6ca027SAl Viro } 19275b6ca027SAl Viro 192831e6b01fSNick Piggin nd->root.mnt = NULL; 192931e6b01fSNick Piggin 193048a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1931fd2f7cb5SAl Viro if (*s == '/') { 1932e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19338b61e74fSAl Viro rcu_read_lock(); 19347bd88377SAl Viro nd->seq = set_root_rcu(nd); 1935e41f7d4eSAl Viro } else { 1936e41f7d4eSAl Viro set_root(nd); 1937e41f7d4eSAl Viro path_get(&nd->root); 1938e41f7d4eSAl Viro } 193931e6b01fSNick Piggin nd->path = nd->root; 194031e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1941e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 194231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1943c28cc364SNick Piggin unsigned seq; 194431e6b01fSNick Piggin 19458b61e74fSAl Viro rcu_read_lock(); 194631e6b01fSNick Piggin 1947c28cc364SNick Piggin do { 1948c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 194931e6b01fSNick Piggin nd->path = fs->pwd; 1950c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1951c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1952e41f7d4eSAl Viro } else { 1953e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1954e41f7d4eSAl Viro } 195531e6b01fSNick Piggin } else { 1956582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19572903ff01SAl Viro struct fd f = fdget_raw(dfd); 195831e6b01fSNick Piggin struct dentry *dentry; 195931e6b01fSNick Piggin 19602903ff01SAl Viro if (!f.file) 19612903ff01SAl Viro return -EBADF; 196231e6b01fSNick Piggin 19632903ff01SAl Viro dentry = f.file->f_path.dentry; 196431e6b01fSNick Piggin 1965fd2f7cb5SAl Viro if (*s) { 196644b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19672903ff01SAl Viro fdput(f); 19682903ff01SAl Viro return -ENOTDIR; 1969f52e0c11SAl Viro } 19702903ff01SAl Viro } 19712903ff01SAl Viro 19722903ff01SAl Viro nd->path = f.file->f_path; 1973e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19749c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19755e53084dSAl Viro nd->base = f.file; 1976c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19778b61e74fSAl Viro rcu_read_lock(); 19785590ff0dSUlrich Drepper } else { 19792903ff01SAl Viro path_get(&nd->path); 19802903ff01SAl Viro fdput(f); 19811da177e4SLinus Torvalds } 1982e41f7d4eSAl Viro } 1983e41f7d4eSAl Viro 198431e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19854023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1986d465887fSAl Viro goto done; 19874023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1988d465887fSAl Viro goto done; 19894023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19904023bfc9SAl Viro nd->root.mnt = NULL; 19914023bfc9SAl Viro rcu_read_unlock(); 19924023bfc9SAl Viro return -ECHILD; 1993d465887fSAl Viro done: 1994756daf26SNeilBrown nd->total_link_count = 0; 1995dc7af8dcSAl Viro return link_path_walk(s, nd); 19969b4a9b14SAl Viro } 19979b4a9b14SAl Viro 1998893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1999893b7775SAl Viro { 2000893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 2001893b7775SAl Viro path_put(&nd->root); 2002893b7775SAl Viro nd->root.mnt = NULL; 2003893b7775SAl Viro } 2004893b7775SAl Viro if (unlikely(nd->base)) 2005893b7775SAl Viro fput(nd->base); 20069b4a9b14SAl Viro } 20079b4a9b14SAl Viro 20081d8e03d3SAl Viro static int trailing_symlink(struct nameidata *nd) 200995fa25d9SAl Viro { 201095fa25d9SAl Viro const char *s; 20111d8e03d3SAl Viro int error = may_follow_link(&nd->link, nd); 201295fa25d9SAl Viro if (unlikely(error)) 201395fa25d9SAl Viro return error; 201495fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 20153b2e7f75SAl Viro s = get_link(nd); 20161bc4b813SAl Viro if (unlikely(IS_ERR(s))) { 20171bc4b813SAl Viro terminate_walk(nd); 201895fa25d9SAl Viro return PTR_ERR(s); 20191bc4b813SAl Viro } 20209ea57b72SAl Viro if (unlikely(!s)) 202195fa25d9SAl Viro return 0; 202295fa25d9SAl Viro if (*s == '/') { 202395fa25d9SAl Viro if (!nd->root.mnt) 202495fa25d9SAl Viro set_root(nd); 202595fa25d9SAl Viro path_put(&nd->path); 202695fa25d9SAl Viro nd->path = nd->root; 202795fa25d9SAl Viro path_get(&nd->root); 202895fa25d9SAl Viro nd->flags |= LOOKUP_JUMPED; 202995fa25d9SAl Viro } 203095fa25d9SAl Viro nd->inode = nd->path.dentry->d_inode; 2031939724dfSAl Viro nd->stack[0].name = NULL; 20328eff733aSAl Viro return link_path_walk(s, nd); 203395fa25d9SAl Viro } 203495fa25d9SAl Viro 2035caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2036bd92d7feSAl Viro { 2037f0a9ba70SAl Viro int err; 2038bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2039bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2040bd92d7feSAl Viro 2041bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 20424693a547SAl Viro err = walk_component(nd, 20434693a547SAl Viro nd->flags & LOOKUP_FOLLOW 20444693a547SAl Viro ? nd->depth 20454693a547SAl Viro ? WALK_PUT | WALK_GET 20464693a547SAl Viro : WALK_GET 20474693a547SAl Viro : 0); 2048f0a9ba70SAl Viro if (err < 0) 2049f0a9ba70SAl Viro terminate_walk(nd); 2050f0a9ba70SAl Viro return err; 2051bd92d7feSAl Viro } 2052bd92d7feSAl Viro 20539b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20545eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20559b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20569b4a9b14SAl Viro { 2057bd92d7feSAl Viro int err; 205831e6b01fSNick Piggin 205931e6b01fSNick Piggin /* 206031e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 206131e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 206231e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 206331e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 206431e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 206531e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 206631e6b01fSNick Piggin * analogue, foo_rcu(). 206731e6b01fSNick Piggin * 206831e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 206931e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 207031e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 207131e6b01fSNick Piggin * be able to complete). 207231e6b01fSNick Piggin */ 20736e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2074bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2075191d7f73SAl Viro while ((err = lookup_last(nd)) > 0) { 20761d8e03d3SAl Viro err = trailing_symlink(nd); 20776d7b5aaeSAl Viro if (err) 20786d7b5aaeSAl Viro break; 2079bd92d7feSAl Viro } 2080bd92d7feSAl Viro } 2081ee0827cdSAl Viro 20829f1fafeeSAl Viro if (!err) 20839f1fafeeSAl Viro err = complete_walk(nd); 2084bd92d7feSAl Viro 2085bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 208644b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2087bd92d7feSAl Viro path_put(&nd->path); 2088bd23a539SAl Viro err = -ENOTDIR; 2089bd92d7feSAl Viro } 2090bd92d7feSAl Viro } 209116c2cd71SAl Viro 2092893b7775SAl Viro path_cleanup(nd); 2093bd92d7feSAl Viro return err; 209431e6b01fSNick Piggin } 209531e6b01fSNick Piggin 2096873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2097873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2098873f1eedSJeff Layton { 2099894bc8c4SAl Viro int retval; 2100756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2101894bc8c4SAl Viro 2102894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2103873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 21045eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2105873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 21065eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2107873f1eedSJeff Layton 2108873f1eedSJeff Layton if (likely(!retval)) 2109adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2110756daf26SNeilBrown restore_nameidata(saved_nd); 2111873f1eedSJeff Layton return retval; 2112873f1eedSJeff Layton } 2113873f1eedSJeff Layton 211479714f72SAl Viro /* does lookup, returns the object with parent locked */ 211579714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21165590ff0dSUlrich Drepper { 211751689104SPaul Moore struct filename *filename = getname_kernel(name); 211879714f72SAl Viro struct nameidata nd; 211979714f72SAl Viro struct dentry *d; 212051689104SPaul Moore int err; 212151689104SPaul Moore 212251689104SPaul Moore if (IS_ERR(filename)) 212351689104SPaul Moore return ERR_CAST(filename); 212451689104SPaul Moore 212551689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 212651689104SPaul Moore if (err) { 212751689104SPaul Moore d = ERR_PTR(err); 212851689104SPaul Moore goto out; 212951689104SPaul Moore } 213079714f72SAl Viro if (nd.last_type != LAST_NORM) { 213179714f72SAl Viro path_put(&nd.path); 213251689104SPaul Moore d = ERR_PTR(-EINVAL); 213351689104SPaul Moore goto out; 213479714f72SAl Viro } 213579714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21361e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 213779714f72SAl Viro if (IS_ERR(d)) { 213879714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 213979714f72SAl Viro path_put(&nd.path); 214051689104SPaul Moore goto out; 214179714f72SAl Viro } 214279714f72SAl Viro *path = nd.path; 214351689104SPaul Moore out: 214451689104SPaul Moore putname(filename); 214579714f72SAl Viro return d; 21465590ff0dSUlrich Drepper } 21475590ff0dSUlrich Drepper 2148d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2149d1811465SAl Viro { 2150d1811465SAl Viro struct nameidata nd; 215174eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 215274eb8cc5SAl Viro int res = PTR_ERR(filename); 215374eb8cc5SAl Viro 215474eb8cc5SAl Viro if (!IS_ERR(filename)) { 215574eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 215674eb8cc5SAl Viro putname(filename); 2157d1811465SAl Viro if (!res) 2158d1811465SAl Viro *path = nd.path; 215974eb8cc5SAl Viro } 2160d1811465SAl Viro return res; 2161d1811465SAl Viro } 21624d359507SAl Viro EXPORT_SYMBOL(kern_path); 2163d1811465SAl Viro 216416f18200SJosef 'Jeff' Sipek /** 216516f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 216616f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 216716f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 216816f18200SJosef 'Jeff' Sipek * @name: pointer to file name 216916f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2170e0a01249SAl Viro * @path: pointer to struct path to fill 217116f18200SJosef 'Jeff' Sipek */ 217216f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 217316f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2174e0a01249SAl Viro struct path *path) 217516f18200SJosef 'Jeff' Sipek { 217674eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 217774eb8cc5SAl Viro int err = PTR_ERR(filename); 217874eb8cc5SAl Viro 217974eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 218074eb8cc5SAl Viro 218174eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 218274eb8cc5SAl Viro if (!IS_ERR(filename)) { 2183e0a01249SAl Viro struct nameidata nd; 2184e0a01249SAl Viro nd.root.dentry = dentry; 2185e0a01249SAl Viro nd.root.mnt = mnt; 218674eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 218774eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2188e0a01249SAl Viro if (!err) 2189e0a01249SAl Viro *path = nd.path; 219074eb8cc5SAl Viro putname(filename); 219174eb8cc5SAl Viro } 2192e0a01249SAl Viro return err; 219316f18200SJosef 'Jeff' Sipek } 21944d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 219516f18200SJosef 'Jeff' Sipek 2196eead1911SChristoph Hellwig /** 2197a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2198eead1911SChristoph Hellwig * @name: pathname component to lookup 2199eead1911SChristoph Hellwig * @base: base directory to lookup from 2200eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2201eead1911SChristoph Hellwig * 2202a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 22039e7543e9SAl Viro * not be called by generic code. 2204eead1911SChristoph Hellwig */ 2205057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2206057f6c01SJames Morris { 2207057f6c01SJames Morris struct qstr this; 22086a96ba54SAl Viro unsigned int c; 2209cda309deSMiklos Szeredi int err; 2210057f6c01SJames Morris 22112f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 22122f9092e1SDavid Woodhouse 22136a96ba54SAl Viro this.name = name; 22146a96ba54SAl Viro this.len = len; 22150145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22166a96ba54SAl Viro if (!len) 22176a96ba54SAl Viro return ERR_PTR(-EACCES); 22186a96ba54SAl Viro 221921d8a15aSAl Viro if (unlikely(name[0] == '.')) { 222021d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 222121d8a15aSAl Viro return ERR_PTR(-EACCES); 222221d8a15aSAl Viro } 222321d8a15aSAl Viro 22246a96ba54SAl Viro while (len--) { 22256a96ba54SAl Viro c = *(const unsigned char *)name++; 22266a96ba54SAl Viro if (c == '/' || c == '\0') 22276a96ba54SAl Viro return ERR_PTR(-EACCES); 22286a96ba54SAl Viro } 22295a202bcdSAl Viro /* 22305a202bcdSAl Viro * See if the low-level filesystem might want 22315a202bcdSAl Viro * to use its own hash.. 22325a202bcdSAl Viro */ 22335a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2234da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22355a202bcdSAl Viro if (err < 0) 22365a202bcdSAl Viro return ERR_PTR(err); 22375a202bcdSAl Viro } 2238eead1911SChristoph Hellwig 2239cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2240cda309deSMiklos Szeredi if (err) 2241cda309deSMiklos Szeredi return ERR_PTR(err); 2242cda309deSMiklos Szeredi 224372bd866aSAl Viro return __lookup_hash(&this, base, 0); 2244057f6c01SJames Morris } 22454d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2246057f6c01SJames Morris 22471fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22481fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22491da177e4SLinus Torvalds { 22502d8f3038SAl Viro struct nameidata nd; 225191a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22521da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22531da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22542d8f3038SAl Viro 22552d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22562d8f3038SAl Viro 2257873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22581da177e4SLinus Torvalds putname(tmp); 22592d8f3038SAl Viro if (!err) 22602d8f3038SAl Viro *path = nd.path; 22611da177e4SLinus Torvalds } 22621da177e4SLinus Torvalds return err; 22631da177e4SLinus Torvalds } 22641da177e4SLinus Torvalds 22651fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22661fa1e7f6SAndy Whitcroft struct path *path) 22671fa1e7f6SAndy Whitcroft { 2268f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22691fa1e7f6SAndy Whitcroft } 22704d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22711fa1e7f6SAndy Whitcroft 2272873f1eedSJeff Layton /* 2273873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2274873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2275873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2276873f1eedSJeff Layton * path-walking is complete. 2277873f1eedSJeff Layton */ 227891a27b2aSJeff Layton static struct filename * 2279f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2280f5beed75SAl Viro struct path *parent, 2281f5beed75SAl Viro struct qstr *last, 2282f5beed75SAl Viro int *type, 22839e790bd6SJeff Layton unsigned int flags) 22842ad94ae6SAl Viro { 2285f5beed75SAl Viro struct nameidata nd; 228691a27b2aSJeff Layton struct filename *s = getname(path); 22872ad94ae6SAl Viro int error; 22882ad94ae6SAl Viro 22899e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22909e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22919e790bd6SJeff Layton 22922ad94ae6SAl Viro if (IS_ERR(s)) 229391a27b2aSJeff Layton return s; 22942ad94ae6SAl Viro 2295f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 229691a27b2aSJeff Layton if (error) { 22972ad94ae6SAl Viro putname(s); 229891a27b2aSJeff Layton return ERR_PTR(error); 229991a27b2aSJeff Layton } 2300f5beed75SAl Viro *parent = nd.path; 2301f5beed75SAl Viro *last = nd.last; 2302f5beed75SAl Viro *type = nd.last_type; 23032ad94ae6SAl Viro 230491a27b2aSJeff Layton return s; 23052ad94ae6SAl Viro } 23062ad94ae6SAl Viro 23078033426eSJeff Layton /** 2308197df04cSAl Viro * mountpoint_last - look up last component for umount 23098033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 23108033426eSJeff Layton * @path: pointer to container for result 23118033426eSJeff Layton * 23128033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 23138033426eSJeff Layton * need to resolve the path without doing any revalidation. 23148033426eSJeff Layton * 23158033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23168033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23178033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23188033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23198033426eSJeff Layton * bogus and it doesn't exist. 23208033426eSJeff Layton * 23218033426eSJeff Layton * Returns: 23228033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23238033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23248033426eSJeff Layton * put in this case. 23258033426eSJeff Layton * 23268033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23278033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23288033426eSJeff Layton * The nd->path reference will also be put. 23298033426eSJeff Layton * 23308033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23318033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23328033426eSJeff Layton * to the link, and nd->path will *not* be put. 23338033426eSJeff Layton */ 23348033426eSJeff Layton static int 2335197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23368033426eSJeff Layton { 23378033426eSJeff Layton int error = 0; 23388033426eSJeff Layton struct dentry *dentry; 23398033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23408033426eSJeff Layton 234135759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 234235759521SAl Viro if (nd->flags & LOOKUP_RCU) { 234335759521SAl Viro if (unlazy_walk(nd, NULL)) { 23448033426eSJeff Layton error = -ECHILD; 234535759521SAl Viro goto out; 234635759521SAl Viro } 23478033426eSJeff Layton } 23488033426eSJeff Layton 23498033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23508033426eSJeff Layton 23518033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23528033426eSJeff Layton error = handle_dots(nd, nd->last_type); 235335759521SAl Viro if (error) 235435759521SAl Viro goto out; 23558033426eSJeff Layton dentry = dget(nd->path.dentry); 235635759521SAl Viro goto done; 23578033426eSJeff Layton } 23588033426eSJeff Layton 23598033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23608033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23618033426eSJeff Layton if (!dentry) { 23628033426eSJeff Layton /* 23638033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23648033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23658033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23668033426eSJeff Layton */ 23678033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23688033426eSJeff Layton if (!dentry) { 23698033426eSJeff Layton error = -ENOMEM; 2370bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 237135759521SAl Viro goto out; 23728033426eSJeff Layton } 237335759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 237435759521SAl Viro error = PTR_ERR(dentry); 2375bcceeebaSDave Jones if (IS_ERR(dentry)) { 2376bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 237735759521SAl Viro goto out; 23788033426eSJeff Layton } 2379bcceeebaSDave Jones } 23808033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23818033426eSJeff Layton 238235759521SAl Viro done: 2383698934dfSDavid Howells if (d_is_negative(dentry)) { 23848033426eSJeff Layton error = -ENOENT; 23858033426eSJeff Layton dput(dentry); 238635759521SAl Viro goto out; 238735759521SAl Viro } 2388191d7f73SAl Viro if (nd->depth) 2389191d7f73SAl Viro put_link(nd); 23908033426eSJeff Layton path->dentry = dentry; 2391295dc39dSVasily Averin path->mnt = nd->path.mnt; 2392d63ff28fSAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW); 2393d63ff28fSAl Viro if (unlikely(error)) { 2394d63ff28fSAl Viro if (error < 0) 2395d63ff28fSAl Viro goto out; 2396d63ff28fSAl Viro return error; 2397caa85634SAl Viro } 2398295dc39dSVasily Averin mntget(path->mnt); 23998033426eSJeff Layton follow_mount(path); 240035759521SAl Viro error = 0; 240135759521SAl Viro out: 24028033426eSJeff Layton terminate_walk(nd); 24038033426eSJeff Layton return error; 24048033426eSJeff Layton } 24058033426eSJeff Layton 24068033426eSJeff Layton /** 2407197df04cSAl Viro * path_mountpoint - look up a path to be umounted 24088033426eSJeff Layton * @dfd: directory file descriptor to start walk from 24098033426eSJeff Layton * @name: full pathname to walk 2410606d6fe3SRandy Dunlap * @path: pointer to container for result 24118033426eSJeff Layton * @flags: lookup flags 24128033426eSJeff Layton * 24138033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2414606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 24158033426eSJeff Layton */ 24168033426eSJeff Layton static int 2417668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 241846afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24198033426eSJeff Layton { 242046afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 24218033426eSJeff Layton if (unlikely(err)) 2422115cbfdcSAl Viro goto out; 24238033426eSJeff Layton 2424191d7f73SAl Viro while ((err = mountpoint_last(nd, path)) > 0) { 24251d8e03d3SAl Viro err = trailing_symlink(nd); 24268033426eSJeff Layton if (err) 24278033426eSJeff Layton break; 24288033426eSJeff Layton } 24298033426eSJeff Layton out: 243046afd6f6SAl Viro path_cleanup(nd); 24318033426eSJeff Layton return err; 24328033426eSJeff Layton } 24338033426eSJeff Layton 24342d864651SAl Viro static int 2435668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24362d864651SAl Viro unsigned int flags) 24372d864651SAl Viro { 2438756daf26SNeilBrown struct nameidata nd, *saved; 2439cbaab2dbSAl Viro int error; 2440668696dcSAl Viro if (IS_ERR(name)) 2441668696dcSAl Viro return PTR_ERR(name); 2442756daf26SNeilBrown saved = set_nameidata(&nd); 244346afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24442d864651SAl Viro if (unlikely(error == -ECHILD)) 244546afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24462d864651SAl Viro if (unlikely(error == -ESTALE)) 244746afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24482d864651SAl Viro if (likely(!error)) 2449668696dcSAl Viro audit_inode(name, path->dentry, 0); 2450756daf26SNeilBrown restore_nameidata(saved); 2451668696dcSAl Viro putname(name); 24522d864651SAl Viro return error; 24532d864651SAl Viro } 24542d864651SAl Viro 24558033426eSJeff Layton /** 2456197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24578033426eSJeff Layton * @dfd: directory file descriptor 24588033426eSJeff Layton * @name: pathname from userland 24598033426eSJeff Layton * @flags: lookup flags 24608033426eSJeff Layton * @path: pointer to container to hold result 24618033426eSJeff Layton * 24628033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24638033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24648033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24658033426eSJeff Layton * and avoid revalidating the last component. 24668033426eSJeff Layton * 24678033426eSJeff Layton * Returns 0 and populates "path" on success. 24688033426eSJeff Layton */ 24698033426eSJeff Layton int 2470197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24718033426eSJeff Layton struct path *path) 24728033426eSJeff Layton { 2473cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24748033426eSJeff Layton } 24758033426eSJeff Layton 24762d864651SAl Viro int 24772d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24782d864651SAl Viro unsigned int flags) 24792d864651SAl Viro { 2480cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24812d864651SAl Viro } 24822d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24832d864651SAl Viro 2484cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24851da177e4SLinus Torvalds { 24868e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2487da9592edSDavid Howells 24888e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24891da177e4SLinus Torvalds return 0; 24908e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24911da177e4SLinus Torvalds return 0; 249223adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24931da177e4SLinus Torvalds } 2494cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24951da177e4SLinus Torvalds 24961da177e4SLinus Torvalds /* 24971da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24981da177e4SLinus Torvalds * whether the type of victim is right. 24991da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 25001da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 25011da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 25021da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 25031da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 25041da177e4SLinus Torvalds * a. be owner of dir, or 25051da177e4SLinus Torvalds * b. be owner of victim, or 25061da177e4SLinus Torvalds * c. have CAP_FOWNER capability 25071da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 25081da177e4SLinus Torvalds * links pointing to it. 25091da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 25101da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 25111da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 25121da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 25131da177e4SLinus Torvalds * nfs_async_unlink(). 25141da177e4SLinus Torvalds */ 2515b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25161da177e4SLinus Torvalds { 2517b18825a7SDavid Howells struct inode *inode = victim->d_inode; 25181da177e4SLinus Torvalds int error; 25191da177e4SLinus Torvalds 2520b18825a7SDavid Howells if (d_is_negative(victim)) 25211da177e4SLinus Torvalds return -ENOENT; 2522b18825a7SDavid Howells BUG_ON(!inode); 25231da177e4SLinus Torvalds 25241da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25254fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25261da177e4SLinus Torvalds 2527f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25281da177e4SLinus Torvalds if (error) 25291da177e4SLinus Torvalds return error; 25301da177e4SLinus Torvalds if (IS_APPEND(dir)) 25311da177e4SLinus Torvalds return -EPERM; 2532b18825a7SDavid Howells 2533b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2534b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25351da177e4SLinus Torvalds return -EPERM; 25361da177e4SLinus Torvalds if (isdir) { 253744b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25381da177e4SLinus Torvalds return -ENOTDIR; 25391da177e4SLinus Torvalds if (IS_ROOT(victim)) 25401da177e4SLinus Torvalds return -EBUSY; 254144b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25421da177e4SLinus Torvalds return -EISDIR; 25431da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25441da177e4SLinus Torvalds return -ENOENT; 25451da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25461da177e4SLinus Torvalds return -EBUSY; 25471da177e4SLinus Torvalds return 0; 25481da177e4SLinus Torvalds } 25491da177e4SLinus Torvalds 25501da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25511da177e4SLinus Torvalds * dir. 25521da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25531da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25541da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25551da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25561da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25571da177e4SLinus Torvalds */ 2558a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25591da177e4SLinus Torvalds { 256014e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25611da177e4SLinus Torvalds if (child->d_inode) 25621da177e4SLinus Torvalds return -EEXIST; 25631da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25641da177e4SLinus Torvalds return -ENOENT; 2565f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25661da177e4SLinus Torvalds } 25671da177e4SLinus Torvalds 25681da177e4SLinus Torvalds /* 25691da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25701da177e4SLinus Torvalds */ 25711da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25721da177e4SLinus Torvalds { 25731da177e4SLinus Torvalds struct dentry *p; 25741da177e4SLinus Torvalds 25751da177e4SLinus Torvalds if (p1 == p2) { 2576f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25771da177e4SLinus Torvalds return NULL; 25781da177e4SLinus Torvalds } 25791da177e4SLinus Torvalds 2580a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25811da177e4SLinus Torvalds 2582e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2583e2761a11SOGAWA Hirofumi if (p) { 2584f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2585f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25861da177e4SLinus Torvalds return p; 25871da177e4SLinus Torvalds } 25881da177e4SLinus Torvalds 2589e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2590e2761a11SOGAWA Hirofumi if (p) { 2591f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2592f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25931da177e4SLinus Torvalds return p; 25941da177e4SLinus Torvalds } 25951da177e4SLinus Torvalds 2596f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2597d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25981da177e4SLinus Torvalds return NULL; 25991da177e4SLinus Torvalds } 26004d359507SAl Viro EXPORT_SYMBOL(lock_rename); 26011da177e4SLinus Torvalds 26021da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 26031da177e4SLinus Torvalds { 26041b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 26051da177e4SLinus Torvalds if (p1 != p2) { 26061b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2607a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 26081da177e4SLinus Torvalds } 26091da177e4SLinus Torvalds } 26104d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 26111da177e4SLinus Torvalds 26124acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2613312b63fbSAl Viro bool want_excl) 26141da177e4SLinus Torvalds { 2615a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26161da177e4SLinus Torvalds if (error) 26171da177e4SLinus Torvalds return error; 26181da177e4SLinus Torvalds 2619acfa4380SAl Viro if (!dir->i_op->create) 26201da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26211da177e4SLinus Torvalds mode &= S_IALLUGO; 26221da177e4SLinus Torvalds mode |= S_IFREG; 26231da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26241da177e4SLinus Torvalds if (error) 26251da177e4SLinus Torvalds return error; 2626312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2627a74574aaSStephen Smalley if (!error) 2628f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26291da177e4SLinus Torvalds return error; 26301da177e4SLinus Torvalds } 26314d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26321da177e4SLinus Torvalds 263373d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26341da177e4SLinus Torvalds { 26353fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26361da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26371da177e4SLinus Torvalds int error; 26381da177e4SLinus Torvalds 2639bcda7652SAl Viro /* O_PATH? */ 2640bcda7652SAl Viro if (!acc_mode) 2641bcda7652SAl Viro return 0; 2642bcda7652SAl Viro 26431da177e4SLinus Torvalds if (!inode) 26441da177e4SLinus Torvalds return -ENOENT; 26451da177e4SLinus Torvalds 2646c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2647c8fe8f30SChristoph Hellwig case S_IFLNK: 26481da177e4SLinus Torvalds return -ELOOP; 2649c8fe8f30SChristoph Hellwig case S_IFDIR: 2650c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26511da177e4SLinus Torvalds return -EISDIR; 2652c8fe8f30SChristoph Hellwig break; 2653c8fe8f30SChristoph Hellwig case S_IFBLK: 2654c8fe8f30SChristoph Hellwig case S_IFCHR: 26553fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26561da177e4SLinus Torvalds return -EACCES; 2657c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2658c8fe8f30SChristoph Hellwig case S_IFIFO: 2659c8fe8f30SChristoph Hellwig case S_IFSOCK: 26601da177e4SLinus Torvalds flag &= ~O_TRUNC; 2661c8fe8f30SChristoph Hellwig break; 26624a3fd211SDave Hansen } 2663b41572e9SDave Hansen 26643fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2665b41572e9SDave Hansen if (error) 2666b41572e9SDave Hansen return error; 26676146f0d5SMimi Zohar 26681da177e4SLinus Torvalds /* 26691da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26701da177e4SLinus Torvalds */ 26711da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26728737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26737715b521SAl Viro return -EPERM; 26741da177e4SLinus Torvalds if (flag & O_TRUNC) 26757715b521SAl Viro return -EPERM; 26761da177e4SLinus Torvalds } 26771da177e4SLinus Torvalds 26781da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26792e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26807715b521SAl Viro return -EPERM; 26811da177e4SLinus Torvalds 2682f3c7691eSJ. Bruce Fields return 0; 26837715b521SAl Viro } 26847715b521SAl Viro 2685e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26867715b521SAl Viro { 2687e1181ee6SJeff Layton struct path *path = &filp->f_path; 26887715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26897715b521SAl Viro int error = get_write_access(inode); 26901da177e4SLinus Torvalds if (error) 26917715b521SAl Viro return error; 26921da177e4SLinus Torvalds /* 26931da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26941da177e4SLinus Torvalds */ 2695d7a06983SJeff Layton error = locks_verify_locked(filp); 2696be6d3e56SKentaro Takeda if (!error) 2697ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26981da177e4SLinus Torvalds if (!error) { 26997715b521SAl Viro error = do_truncate(path->dentry, 0, 2700d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2701e1181ee6SJeff Layton filp); 27021da177e4SLinus Torvalds } 27031da177e4SLinus Torvalds put_write_access(inode); 2704acd0c935SMimi Zohar return error; 27051da177e4SLinus Torvalds } 27061da177e4SLinus Torvalds 2707d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2708d57999e1SDave Hansen { 27098a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 27108a5e929dSAl Viro flag--; 2711d57999e1SDave Hansen return flag; 2712d57999e1SDave Hansen } 2713d57999e1SDave Hansen 2714d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2715d18e9008SMiklos Szeredi { 2716d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2717d18e9008SMiklos Szeredi if (error) 2718d18e9008SMiklos Szeredi return error; 2719d18e9008SMiklos Szeredi 2720d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2721d18e9008SMiklos Szeredi if (error) 2722d18e9008SMiklos Szeredi return error; 2723d18e9008SMiklos Szeredi 2724d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2725d18e9008SMiklos Szeredi } 2726d18e9008SMiklos Szeredi 27271acf0af9SDavid Howells /* 27281acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27291acf0af9SDavid Howells * dentry. 27301acf0af9SDavid Howells * 27311acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27321acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27331acf0af9SDavid Howells * 27341acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27351acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27361acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27371acf0af9SDavid Howells * 27381acf0af9SDavid Howells * Returns an error code otherwise. 27391acf0af9SDavid Howells */ 27402675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 274130d90494SAl Viro struct path *path, struct file *file, 2742015c3bbcSMiklos Szeredi const struct open_flags *op, 274364894cf8SAl Viro bool got_write, bool need_lookup, 274447237687SAl Viro int *opened) 2745d18e9008SMiklos Szeredi { 2746d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2747d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2748d18e9008SMiklos Szeredi umode_t mode; 2749d18e9008SMiklos Szeredi int error; 2750d18e9008SMiklos Szeredi int acc_mode; 2751d18e9008SMiklos Szeredi int create_error = 0; 2752d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2753116cc022SMiklos Szeredi bool excl; 2754d18e9008SMiklos Szeredi 2755d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2756d18e9008SMiklos Szeredi 2757d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2758d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27592675a4ebSAl Viro error = -ENOENT; 2760d18e9008SMiklos Szeredi goto out; 2761d18e9008SMiklos Szeredi } 2762d18e9008SMiklos Szeredi 276362b259d8SMiklos Szeredi mode = op->mode; 2764d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2765d18e9008SMiklos Szeredi mode &= ~current_umask(); 2766d18e9008SMiklos Szeredi 2767116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2768116cc022SMiklos Szeredi if (excl) 2769d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2770d18e9008SMiklos Szeredi 2771d18e9008SMiklos Szeredi /* 2772d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2773d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2774d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2775d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2776d18e9008SMiklos Szeredi * 2777d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2778d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2779d18e9008SMiklos Szeredi */ 278064894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 278164894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 278264894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2783d18e9008SMiklos Szeredi /* 2784d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2785d18e9008SMiklos Szeredi * back to lookup + open 2786d18e9008SMiklos Szeredi */ 2787d18e9008SMiklos Szeredi goto no_open; 2788d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2789d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 279064894cf8SAl Viro create_error = -EROFS; 2791d18e9008SMiklos Szeredi goto no_open; 2792d18e9008SMiklos Szeredi } else { 2793d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 279464894cf8SAl Viro create_error = -EROFS; 2795d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2796d18e9008SMiklos Szeredi } 2797d18e9008SMiklos Szeredi } 2798d18e9008SMiklos Szeredi 2799d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 280038227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2801d18e9008SMiklos Szeredi if (error) { 2802d18e9008SMiklos Szeredi create_error = error; 2803d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2804d18e9008SMiklos Szeredi goto no_open; 2805d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2806d18e9008SMiklos Szeredi } 2807d18e9008SMiklos Szeredi } 2808d18e9008SMiklos Szeredi 2809d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2810d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2811d18e9008SMiklos Szeredi 281230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 281330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 281430d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 281547237687SAl Viro opened); 2816d9585277SAl Viro if (error < 0) { 2817d9585277SAl Viro if (create_error && error == -ENOENT) 2818d9585277SAl Viro error = create_error; 2819d18e9008SMiklos Szeredi goto out; 2820d18e9008SMiklos Szeredi } 2821d18e9008SMiklos Szeredi 2822d9585277SAl Viro if (error) { /* returned 1, that is */ 282330d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28242675a4ebSAl Viro error = -EIO; 2825d18e9008SMiklos Szeredi goto out; 2826d18e9008SMiklos Szeredi } 282730d90494SAl Viro if (file->f_path.dentry) { 2828d18e9008SMiklos Szeredi dput(dentry); 282930d90494SAl Viro dentry = file->f_path.dentry; 2830d18e9008SMiklos Szeredi } 283103da633aSAl Viro if (*opened & FILE_CREATED) 283203da633aSAl Viro fsnotify_create(dir, dentry); 283303da633aSAl Viro if (!dentry->d_inode) { 283403da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 283503da633aSAl Viro if (create_error) { 283662b2ce96SSage Weil error = create_error; 283762b2ce96SSage Weil goto out; 283862b2ce96SSage Weil } 283903da633aSAl Viro } else { 284003da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 284103da633aSAl Viro error = -EEXIST; 284203da633aSAl Viro goto out; 284303da633aSAl Viro } 284403da633aSAl Viro } 2845d18e9008SMiklos Szeredi goto looked_up; 2846d18e9008SMiklos Szeredi } 2847d18e9008SMiklos Szeredi 2848d18e9008SMiklos Szeredi /* 2849d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2850d18e9008SMiklos Szeredi * here. 2851d18e9008SMiklos Szeredi */ 285203da633aSAl Viro acc_mode = op->acc_mode; 285303da633aSAl Viro if (*opened & FILE_CREATED) { 285403da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 285503da633aSAl Viro fsnotify_create(dir, dentry); 285603da633aSAl Viro acc_mode = MAY_OPEN; 285703da633aSAl Viro } 28582675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28592675a4ebSAl Viro if (error) 28602675a4ebSAl Viro fput(file); 2861d18e9008SMiklos Szeredi 2862d18e9008SMiklos Szeredi out: 2863d18e9008SMiklos Szeredi dput(dentry); 28642675a4ebSAl Viro return error; 2865d18e9008SMiklos Szeredi 2866d18e9008SMiklos Szeredi no_open: 2867d18e9008SMiklos Szeredi if (need_lookup) { 286872bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2869d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28702675a4ebSAl Viro return PTR_ERR(dentry); 2871d18e9008SMiklos Szeredi 2872d18e9008SMiklos Szeredi if (create_error) { 2873d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2874d18e9008SMiklos Szeredi 28752675a4ebSAl Viro error = create_error; 2876d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2877d18e9008SMiklos Szeredi if (!dentry->d_inode) 2878d18e9008SMiklos Szeredi goto out; 2879d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2880d18e9008SMiklos Szeredi goto out; 2881d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2882e36cb0b8SDavid Howells d_is_reg(dentry)) { 2883d18e9008SMiklos Szeredi goto out; 2884d18e9008SMiklos Szeredi } 2885d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2886d18e9008SMiklos Szeredi } 2887d18e9008SMiklos Szeredi } 2888d18e9008SMiklos Szeredi looked_up: 2889d18e9008SMiklos Szeredi path->dentry = dentry; 2890d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28912675a4ebSAl Viro return 1; 2892d18e9008SMiklos Szeredi } 2893d18e9008SMiklos Szeredi 289431e6b01fSNick Piggin /* 28951acf0af9SDavid Howells * Look up and maybe create and open the last component. 2896d58ffd35SMiklos Szeredi * 2897d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2898d58ffd35SMiklos Szeredi * 28991acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 29001acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 29011acf0af9SDavid Howells * 29021acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 29031acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 29041acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 29051acf0af9SDavid Howells * specified then a negative dentry may be returned. 29061acf0af9SDavid Howells * 29071acf0af9SDavid Howells * An error code is returned otherwise. 29081acf0af9SDavid Howells * 29091acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 29101acf0af9SDavid Howells * cleared otherwise prior to returning. 2911d58ffd35SMiklos Szeredi */ 29122675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 291330d90494SAl Viro struct file *file, 2914d58ffd35SMiklos Szeredi const struct open_flags *op, 291564894cf8SAl Viro bool got_write, int *opened) 2916d58ffd35SMiklos Szeredi { 2917d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 291854ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2919d58ffd35SMiklos Szeredi struct dentry *dentry; 2920d58ffd35SMiklos Szeredi int error; 292154ef4872SMiklos Szeredi bool need_lookup; 2922d58ffd35SMiklos Szeredi 292347237687SAl Viro *opened &= ~FILE_CREATED; 2924201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2925d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29262675a4ebSAl Viro return PTR_ERR(dentry); 2927d58ffd35SMiklos Szeredi 2928d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2929d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2930d18e9008SMiklos Szeredi goto out_no_open; 2931d18e9008SMiklos Szeredi 2932d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 293364894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 293447237687SAl Viro need_lookup, opened); 2935d18e9008SMiklos Szeredi } 2936d18e9008SMiklos Szeredi 293754ef4872SMiklos Szeredi if (need_lookup) { 293854ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 293954ef4872SMiklos Szeredi 294072bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 294154ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29422675a4ebSAl Viro return PTR_ERR(dentry); 294354ef4872SMiklos Szeredi } 294454ef4872SMiklos Szeredi 2945d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2946d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2947d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2948d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2949d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2950d58ffd35SMiklos Szeredi /* 2951d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2952d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2953d58ffd35SMiklos Szeredi * the time when the file is created and when 2954d58ffd35SMiklos Szeredi * a permanent write count is taken through 2955015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2956d58ffd35SMiklos Szeredi */ 295764894cf8SAl Viro if (!got_write) { 295864894cf8SAl Viro error = -EROFS; 2959d58ffd35SMiklos Szeredi goto out_dput; 296064894cf8SAl Viro } 296147237687SAl Viro *opened |= FILE_CREATED; 2962d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2963d58ffd35SMiklos Szeredi if (error) 2964d58ffd35SMiklos Szeredi goto out_dput; 2965312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2966312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2967d58ffd35SMiklos Szeredi if (error) 2968d58ffd35SMiklos Szeredi goto out_dput; 2969d58ffd35SMiklos Szeredi } 2970d18e9008SMiklos Szeredi out_no_open: 2971d58ffd35SMiklos Szeredi path->dentry = dentry; 2972d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29732675a4ebSAl Viro return 1; 2974d58ffd35SMiklos Szeredi 2975d58ffd35SMiklos Szeredi out_dput: 2976d58ffd35SMiklos Szeredi dput(dentry); 29772675a4ebSAl Viro return error; 2978d58ffd35SMiklos Szeredi } 2979d58ffd35SMiklos Szeredi 2980d58ffd35SMiklos Szeredi /* 2981fe2d35ffSAl Viro * Handle the last step of open() 298231e6b01fSNick Piggin */ 2983896475d5SAl Viro static int do_last(struct nameidata *nd, 298430d90494SAl Viro struct file *file, const struct open_flags *op, 2985669abf4eSJeff Layton int *opened, struct filename *name) 2986fb1cc555SAl Viro { 2987a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2988ca344a89SAl Viro int open_flag = op->open_flag; 298977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 299064894cf8SAl Viro bool got_write = false; 2991bcda7652SAl Viro int acc_mode = op->acc_mode; 2992a1eb3315SMiklos Szeredi struct inode *inode; 299316b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2994896475d5SAl Viro struct path path; 299516b1c1cdSMiklos Szeredi bool retried = false; 299616c2cd71SAl Viro int error; 2997fb1cc555SAl Viro 2998c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2999c3e380b0SAl Viro nd->flags |= op->intent; 3000c3e380b0SAl Viro 3001bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3002fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 300370291aecSAl Viro if (unlikely(error)) { 300470291aecSAl Viro terminate_walk(nd); 30052675a4ebSAl Viro return error; 300670291aecSAl Viro } 3007e83db167SMiklos Szeredi goto finish_open; 30081f36f774SAl Viro } 3009a2c36b45SAl Viro 3010ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3011fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3012fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3013fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3014896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 301571574865SMiklos Szeredi if (likely(!error)) 301671574865SMiklos Szeredi goto finish_lookup; 301771574865SMiklos Szeredi 3018ce57dfc1SAl Viro if (error < 0) 30192675a4ebSAl Viro goto out; 3020a1eb3315SMiklos Szeredi 302137d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3022b6183df7SMiklos Szeredi } else { 3023fe2d35ffSAl Viro /* create side of things */ 3024a3fbbde7SAl Viro /* 3025b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3026b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3027b6183df7SMiklos Szeredi * about to look up 3028a3fbbde7SAl Viro */ 30299f1fafeeSAl Viro error = complete_walk(nd); 3030191d7f73SAl Viro if (error) { 3031191d7f73SAl Viro if (nd->depth) 3032191d7f73SAl Viro put_link(nd); 30332675a4ebSAl Viro return error; 3034191d7f73SAl Viro } 3035fe2d35ffSAl Viro 303633e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 303716c2cd71SAl Viro error = -EISDIR; 30381f36f774SAl Viro /* trailing slashes? */ 303931e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 30402675a4ebSAl Viro goto out; 3041b6183df7SMiklos Szeredi } 30421f36f774SAl Viro 304316b1c1cdSMiklos Szeredi retry_lookup: 304464894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 304564894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 304664894cf8SAl Viro if (!error) 304764894cf8SAl Viro got_write = true; 304864894cf8SAl Viro /* 304964894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 305064894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 305164894cf8SAl Viro * dropping this one anyway. 305264894cf8SAl Viro */ 305364894cf8SAl Viro } 3054a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3055896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3056fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3057fb1cc555SAl Viro 30582675a4ebSAl Viro if (error <= 0) { 30592675a4ebSAl Viro if (error) 3060d58ffd35SMiklos Szeredi goto out; 30616c0d46c4SAl Viro 306247237687SAl Viro if ((*opened & FILE_CREATED) || 3063496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 306477d660a8SMiklos Szeredi will_truncate = false; 3065d18e9008SMiklos Szeredi 3066adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3067d18e9008SMiklos Szeredi goto opened; 3068d18e9008SMiklos Szeredi } 3069d18e9008SMiklos Szeredi 307047237687SAl Viro if (*opened & FILE_CREATED) { 30719b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3072ca344a89SAl Viro open_flag &= ~O_TRUNC; 307377d660a8SMiklos Szeredi will_truncate = false; 3074bcda7652SAl Viro acc_mode = MAY_OPEN; 3075896475d5SAl Viro path_to_nameidata(&path, nd); 3076e83db167SMiklos Szeredi goto finish_open_created; 3077fb1cc555SAl Viro } 3078fb1cc555SAl Viro 3079fb1cc555SAl Viro /* 30803134f37eSJeff Layton * create/update audit record if it already exists. 3081fb1cc555SAl Viro */ 3082896475d5SAl Viro if (d_is_positive(path.dentry)) 3083896475d5SAl Viro audit_inode(name, path.dentry, 0); 3084fb1cc555SAl Viro 3085d18e9008SMiklos Szeredi /* 3086d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3087d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3088d18e9008SMiklos Szeredi * necessary...) 3089d18e9008SMiklos Szeredi */ 309064894cf8SAl Viro if (got_write) { 3091d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 309264894cf8SAl Viro got_write = false; 3093d18e9008SMiklos Szeredi } 3094d18e9008SMiklos Szeredi 3095fb1cc555SAl Viro error = -EEXIST; 3096f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3097fb1cc555SAl Viro goto exit_dput; 3098fb1cc555SAl Viro 3099756daf26SNeilBrown error = follow_managed(&path, nd); 31009875cf80SDavid Howells if (error < 0) 3101fb1cc555SAl Viro goto exit_dput; 3102fb1cc555SAl Viro 3103a3fbbde7SAl Viro if (error) 3104a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3105a3fbbde7SAl Viro 3106decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3107896475d5SAl Viro inode = path.dentry->d_inode; 3108fb1cc555SAl Viro error = -ENOENT; 3109896475d5SAl Viro if (d_is_negative(path.dentry)) { 3110896475d5SAl Viro path_to_nameidata(&path, nd); 31112675a4ebSAl Viro goto out; 311254c33e7fSMiklos Szeredi } 3113766c4cbfSAl Viro finish_lookup: 3114191d7f73SAl Viro if (nd->depth) 3115191d7f73SAl Viro put_link(nd); 3116d63ff28fSAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW); 3117d63ff28fSAl Viro if (unlikely(error)) { 3118d63ff28fSAl Viro if (error < 0) 3119d63ff28fSAl Viro goto out; 3120d63ff28fSAl Viro return error; 3121d45ea867SMiklos Szeredi } 3122fb1cc555SAl Viro 3123896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3124896475d5SAl Viro path_to_nameidata(&path, nd); 3125a5cfe2d5SAl Viro error = -ELOOP; 3126a5cfe2d5SAl Viro goto out; 3127a5cfe2d5SAl Viro } 3128a5cfe2d5SAl Viro 3129896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3130896475d5SAl Viro path_to_nameidata(&path, nd); 313116b1c1cdSMiklos Szeredi } else { 313216b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3133896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3134896475d5SAl Viro nd->path.dentry = path.dentry; 313516b1c1cdSMiklos Szeredi 313616b1c1cdSMiklos Szeredi } 3137decf3400SMiklos Szeredi nd->inode = inode; 3138a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3139bc77daa7SAl Viro finish_open: 3140a3fbbde7SAl Viro error = complete_walk(nd); 314116b1c1cdSMiklos Szeredi if (error) { 3142191d7f73SAl Viro if (nd->depth) 3143191d7f73SAl Viro put_link(nd); 314416b1c1cdSMiklos Szeredi path_put(&save_parent); 31452675a4ebSAl Viro return error; 314616b1c1cdSMiklos Szeredi } 3147bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3148fb1cc555SAl Viro error = -EISDIR; 314944b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31502675a4ebSAl Viro goto out; 3151af2f5542SMiklos Szeredi error = -ENOTDIR; 315244b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31532675a4ebSAl Viro goto out; 31544bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 315577d660a8SMiklos Szeredi will_truncate = false; 31566c0d46c4SAl Viro 31570f9d1a10SAl Viro if (will_truncate) { 31580f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31590f9d1a10SAl Viro if (error) 31602675a4ebSAl Viro goto out; 316164894cf8SAl Viro got_write = true; 31620f9d1a10SAl Viro } 3163e83db167SMiklos Szeredi finish_open_created: 3164bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3165ca344a89SAl Viro if (error) 31662675a4ebSAl Viro goto out; 31674aa7c634SMiklos Szeredi 31684aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31694aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31704aa7c634SMiklos Szeredi if (!error) { 31714aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31724aa7c634SMiklos Szeredi } else { 317330d90494SAl Viro if (error == -EOPENSTALE) 3174f60dc3dbSMiklos Szeredi goto stale_open; 3175015c3bbcSMiklos Szeredi goto out; 3176f60dc3dbSMiklos Szeredi } 3177a8277b9bSMiklos Szeredi opened: 31782675a4ebSAl Viro error = open_check_o_direct(file); 3179015c3bbcSMiklos Szeredi if (error) 3180015c3bbcSMiklos Szeredi goto exit_fput; 31813034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3182aa4caadbSMiklos Szeredi if (error) 3183aa4caadbSMiklos Szeredi goto exit_fput; 3184aa4caadbSMiklos Szeredi 31850f9d1a10SAl Viro if (will_truncate) { 31862675a4ebSAl Viro error = handle_truncate(file); 3187aa4caadbSMiklos Szeredi if (error) 3188aa4caadbSMiklos Szeredi goto exit_fput; 31890f9d1a10SAl Viro } 3190ca344a89SAl Viro out: 319164894cf8SAl Viro if (got_write) 31920f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 319316b1c1cdSMiklos Szeredi path_put(&save_parent); 3194e276ae67SMiklos Szeredi terminate_walk(nd); 31952675a4ebSAl Viro return error; 3196fb1cc555SAl Viro 3197fb1cc555SAl Viro exit_dput: 3198896475d5SAl Viro path_put_conditional(&path, nd); 3199ca344a89SAl Viro goto out; 3200015c3bbcSMiklos Szeredi exit_fput: 32012675a4ebSAl Viro fput(file); 32022675a4ebSAl Viro goto out; 3203015c3bbcSMiklos Szeredi 3204f60dc3dbSMiklos Szeredi stale_open: 3205f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3206f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3207f60dc3dbSMiklos Szeredi goto out; 3208f60dc3dbSMiklos Szeredi 3209f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3210f60dc3dbSMiklos Szeredi path_put(&nd->path); 3211f60dc3dbSMiklos Szeredi nd->path = save_parent; 3212f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3213f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3214f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 321564894cf8SAl Viro if (got_write) { 3216f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 321764894cf8SAl Viro got_write = false; 3218f60dc3dbSMiklos Szeredi } 3219f60dc3dbSMiklos Szeredi retried = true; 3220f60dc3dbSMiklos Szeredi goto retry_lookup; 3221fb1cc555SAl Viro } 3222fb1cc555SAl Viro 322360545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 322460545d0dSAl Viro struct nameidata *nd, int flags, 322560545d0dSAl Viro const struct open_flags *op, 322660545d0dSAl Viro struct file *file, int *opened) 322760545d0dSAl Viro { 322860545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 322960545d0dSAl Viro struct dentry *dentry, *child; 323060545d0dSAl Viro struct inode *dir; 32315eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 323260545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 323360545d0dSAl Viro if (unlikely(error)) 323460545d0dSAl Viro return error; 323560545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 323660545d0dSAl Viro if (unlikely(error)) 323760545d0dSAl Viro goto out; 323860545d0dSAl Viro /* we want directory to be writable */ 323960545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 324060545d0dSAl Viro if (error) 324160545d0dSAl Viro goto out2; 324260545d0dSAl Viro dentry = nd->path.dentry; 324360545d0dSAl Viro dir = dentry->d_inode; 324460545d0dSAl Viro if (!dir->i_op->tmpfile) { 324560545d0dSAl Viro error = -EOPNOTSUPP; 324660545d0dSAl Viro goto out2; 324760545d0dSAl Viro } 324860545d0dSAl Viro child = d_alloc(dentry, &name); 324960545d0dSAl Viro if (unlikely(!child)) { 325060545d0dSAl Viro error = -ENOMEM; 325160545d0dSAl Viro goto out2; 325260545d0dSAl Viro } 325360545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 325460545d0dSAl Viro nd->flags |= op->intent; 325560545d0dSAl Viro dput(nd->path.dentry); 325660545d0dSAl Viro nd->path.dentry = child; 325760545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 325860545d0dSAl Viro if (error) 325960545d0dSAl Viro goto out2; 326060545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 326169a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 326269a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 326360545d0dSAl Viro if (error) 326460545d0dSAl Viro goto out2; 326560545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 326660545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 326760545d0dSAl Viro if (error) 326860545d0dSAl Viro goto out2; 326960545d0dSAl Viro error = open_check_o_direct(file); 3270f4e0c30cSAl Viro if (error) { 327160545d0dSAl Viro fput(file); 3272f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3273f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3274f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3275f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3276f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3277f4e0c30cSAl Viro } 327860545d0dSAl Viro out2: 327960545d0dSAl Viro mnt_drop_write(nd->path.mnt); 328060545d0dSAl Viro out: 328160545d0dSAl Viro path_put(&nd->path); 328260545d0dSAl Viro return error; 328360545d0dSAl Viro } 328460545d0dSAl Viro 3285669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 328673d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32871da177e4SLinus Torvalds { 328830d90494SAl Viro struct file *file; 328947237687SAl Viro int opened = 0; 329013aab428SAl Viro int error; 329131e6b01fSNick Piggin 329230d90494SAl Viro file = get_empty_filp(); 32931afc99beSAl Viro if (IS_ERR(file)) 32941afc99beSAl Viro return file; 329531e6b01fSNick Piggin 329630d90494SAl Viro file->f_flags = op->open_flag; 329731e6b01fSNick Piggin 3298bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 329960545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3300f15133dfSAl Viro goto out2; 330160545d0dSAl Viro } 330260545d0dSAl Viro 33036e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 330431e6b01fSNick Piggin if (unlikely(error)) 33052675a4ebSAl Viro goto out; 33061da177e4SLinus Torvalds 3307191d7f73SAl Viro while ((error = do_last(nd, file, op, &opened, pathname)) > 0) { 330873d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 33091d8e03d3SAl Viro error = trailing_symlink(nd); 3310c3e380b0SAl Viro if (unlikely(error)) 33112675a4ebSAl Viro break; 3312806b681cSAl Viro } 331310fa8e62SAl Viro out: 3314893b7775SAl Viro path_cleanup(nd); 3315f15133dfSAl Viro out2: 33162675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33172675a4ebSAl Viro BUG_ON(!error); 331830d90494SAl Viro put_filp(file); 3319015c3bbcSMiklos Szeredi } 33202675a4ebSAl Viro if (unlikely(error)) { 33212675a4ebSAl Viro if (error == -EOPENSTALE) { 33222675a4ebSAl Viro if (flags & LOOKUP_RCU) 33232675a4ebSAl Viro error = -ECHILD; 33242675a4ebSAl Viro else 33252675a4ebSAl Viro error = -ESTALE; 33262675a4ebSAl Viro } 33272675a4ebSAl Viro file = ERR_PTR(error); 33282675a4ebSAl Viro } 33292675a4ebSAl Viro return file; 3330de459215SKirill Korotaev } 33311da177e4SLinus Torvalds 3332669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3333f9652e10SAl Viro const struct open_flags *op) 333413aab428SAl Viro { 3335756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3336f9652e10SAl Viro int flags = op->lookup_flags; 333713aab428SAl Viro struct file *filp; 333813aab428SAl Viro 333973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 334013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 334173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 334213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 334373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3344756daf26SNeilBrown restore_nameidata(saved_nd); 334513aab428SAl Viro return filp; 334613aab428SAl Viro } 334713aab428SAl Viro 334873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3349f9652e10SAl Viro const char *name, const struct open_flags *op) 335073d049a4SAl Viro { 3351756daf26SNeilBrown struct nameidata nd, *saved_nd; 335273d049a4SAl Viro struct file *file; 335351689104SPaul Moore struct filename *filename; 3354f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 335573d049a4SAl Viro 335673d049a4SAl Viro nd.root.mnt = mnt; 335773d049a4SAl Viro nd.root.dentry = dentry; 335873d049a4SAl Viro 3359b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 336073d049a4SAl Viro return ERR_PTR(-ELOOP); 336173d049a4SAl Viro 336251689104SPaul Moore filename = getname_kernel(name); 336351689104SPaul Moore if (unlikely(IS_ERR(filename))) 336451689104SPaul Moore return ERR_CAST(filename); 336551689104SPaul Moore 3366756daf26SNeilBrown saved_nd = set_nameidata(&nd); 336751689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 336873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 336951689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 337073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 337151689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3372756daf26SNeilBrown restore_nameidata(saved_nd); 337351689104SPaul Moore putname(filename); 337473d049a4SAl Viro return file; 337573d049a4SAl Viro } 337673d049a4SAl Viro 3377fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33781ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33791da177e4SLinus Torvalds { 3380c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3381ed75e95dSAl Viro struct nameidata nd; 3382c30dabfeSJan Kara int err2; 33831ac12b4bSJeff Layton int error; 33841ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33851ac12b4bSJeff Layton 33861ac12b4bSJeff Layton /* 33871ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33881ac12b4bSJeff Layton * other flags passed in are ignored! 33891ac12b4bSJeff Layton */ 33901ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33911ac12b4bSJeff Layton 3392fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3393ed75e95dSAl Viro if (error) 3394ed75e95dSAl Viro return ERR_PTR(error); 33951da177e4SLinus Torvalds 3396c663e5d8SChristoph Hellwig /* 3397c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3398c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3399c663e5d8SChristoph Hellwig */ 3400ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3401ed75e95dSAl Viro goto out; 3402ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3403ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3404c663e5d8SChristoph Hellwig 3405c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3406c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3407c663e5d8SChristoph Hellwig /* 3408c663e5d8SChristoph Hellwig * Do the final lookup. 3409c663e5d8SChristoph Hellwig */ 3410ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 34116a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 34121da177e4SLinus Torvalds if (IS_ERR(dentry)) 3413a8104a9fSAl Viro goto unlock; 3414c663e5d8SChristoph Hellwig 3415a8104a9fSAl Viro error = -EEXIST; 3416b18825a7SDavid Howells if (d_is_positive(dentry)) 3417a8104a9fSAl Viro goto fail; 3418b18825a7SDavid Howells 3419c663e5d8SChristoph Hellwig /* 3420c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3421c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3422c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3423c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3424c663e5d8SChristoph Hellwig */ 3425ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3426a8104a9fSAl Viro error = -ENOENT; 3427ed75e95dSAl Viro goto fail; 3428e9baf6e5SAl Viro } 3429c30dabfeSJan Kara if (unlikely(err2)) { 3430c30dabfeSJan Kara error = err2; 3431a8104a9fSAl Viro goto fail; 3432c30dabfeSJan Kara } 3433ed75e95dSAl Viro *path = nd.path; 3434e9baf6e5SAl Viro return dentry; 34351da177e4SLinus Torvalds fail: 3436a8104a9fSAl Viro dput(dentry); 3437a8104a9fSAl Viro dentry = ERR_PTR(error); 3438a8104a9fSAl Viro unlock: 3439dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3440c30dabfeSJan Kara if (!err2) 3441c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3442ed75e95dSAl Viro out: 3443dae6ad8fSAl Viro path_put(&nd.path); 3444ed75e95dSAl Viro return dentry; 3445dae6ad8fSAl Viro } 3446fa14a0b8SAl Viro 3447fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3448fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3449fa14a0b8SAl Viro { 345051689104SPaul Moore struct filename *filename = getname_kernel(pathname); 345151689104SPaul Moore struct dentry *res; 345251689104SPaul Moore 345351689104SPaul Moore if (IS_ERR(filename)) 345451689104SPaul Moore return ERR_CAST(filename); 345551689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 345651689104SPaul Moore putname(filename); 345751689104SPaul Moore return res; 3458fa14a0b8SAl Viro } 3459dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3460dae6ad8fSAl Viro 3461921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3462921a1650SAl Viro { 3463921a1650SAl Viro dput(dentry); 3464921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3465a8104a9fSAl Viro mnt_drop_write(path->mnt); 3466921a1650SAl Viro path_put(path); 3467921a1650SAl Viro } 3468921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3469921a1650SAl Viro 34701ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34711ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3472dae6ad8fSAl Viro { 347391a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3474dae6ad8fSAl Viro struct dentry *res; 3475dae6ad8fSAl Viro if (IS_ERR(tmp)) 3476dae6ad8fSAl Viro return ERR_CAST(tmp); 3477fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3478dae6ad8fSAl Viro putname(tmp); 3479dae6ad8fSAl Viro return res; 3480dae6ad8fSAl Viro } 3481dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3482dae6ad8fSAl Viro 34831a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34841da177e4SLinus Torvalds { 3485a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34861da177e4SLinus Torvalds 34871da177e4SLinus Torvalds if (error) 34881da177e4SLinus Torvalds return error; 34891da177e4SLinus Torvalds 3490975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34911da177e4SLinus Torvalds return -EPERM; 34921da177e4SLinus Torvalds 3493acfa4380SAl Viro if (!dir->i_op->mknod) 34941da177e4SLinus Torvalds return -EPERM; 34951da177e4SLinus Torvalds 349608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 349708ce5f16SSerge E. Hallyn if (error) 349808ce5f16SSerge E. Hallyn return error; 349908ce5f16SSerge E. Hallyn 35001da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35011da177e4SLinus Torvalds if (error) 35021da177e4SLinus Torvalds return error; 35031da177e4SLinus Torvalds 35041da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3505a74574aaSStephen Smalley if (!error) 3506f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35071da177e4SLinus Torvalds return error; 35081da177e4SLinus Torvalds } 35094d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35101da177e4SLinus Torvalds 3511f69aac00SAl Viro static int may_mknod(umode_t mode) 3512463c3197SDave Hansen { 3513463c3197SDave Hansen switch (mode & S_IFMT) { 3514463c3197SDave Hansen case S_IFREG: 3515463c3197SDave Hansen case S_IFCHR: 3516463c3197SDave Hansen case S_IFBLK: 3517463c3197SDave Hansen case S_IFIFO: 3518463c3197SDave Hansen case S_IFSOCK: 3519463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3520463c3197SDave Hansen return 0; 3521463c3197SDave Hansen case S_IFDIR: 3522463c3197SDave Hansen return -EPERM; 3523463c3197SDave Hansen default: 3524463c3197SDave Hansen return -EINVAL; 3525463c3197SDave Hansen } 3526463c3197SDave Hansen } 3527463c3197SDave Hansen 35288208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35292e4d0924SHeiko Carstens unsigned, dev) 35301da177e4SLinus Torvalds { 35311da177e4SLinus Torvalds struct dentry *dentry; 3532dae6ad8fSAl Viro struct path path; 3533dae6ad8fSAl Viro int error; 3534972567f1SJeff Layton unsigned int lookup_flags = 0; 35351da177e4SLinus Torvalds 35368e4bfca1SAl Viro error = may_mknod(mode); 35378e4bfca1SAl Viro if (error) 35388e4bfca1SAl Viro return error; 3539972567f1SJeff Layton retry: 3540972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3541dae6ad8fSAl Viro if (IS_ERR(dentry)) 3542dae6ad8fSAl Viro return PTR_ERR(dentry); 35432ad94ae6SAl Viro 3544dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3545ce3b0f8dSAl Viro mode &= ~current_umask(); 3546dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3547be6d3e56SKentaro Takeda if (error) 3548a8104a9fSAl Viro goto out; 35491da177e4SLinus Torvalds switch (mode & S_IFMT) { 35501da177e4SLinus Torvalds case 0: case S_IFREG: 3551312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35521da177e4SLinus Torvalds break; 35531da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3554dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35551da177e4SLinus Torvalds new_decode_dev(dev)); 35561da177e4SLinus Torvalds break; 35571da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3558dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35591da177e4SLinus Torvalds break; 35601da177e4SLinus Torvalds } 3561a8104a9fSAl Viro out: 3562921a1650SAl Viro done_path_create(&path, dentry); 3563972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3564972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3565972567f1SJeff Layton goto retry; 3566972567f1SJeff Layton } 35671da177e4SLinus Torvalds return error; 35681da177e4SLinus Torvalds } 35691da177e4SLinus Torvalds 35708208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35715590ff0dSUlrich Drepper { 35725590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35735590ff0dSUlrich Drepper } 35745590ff0dSUlrich Drepper 357518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35761da177e4SLinus Torvalds { 3577a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35788de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35791da177e4SLinus Torvalds 35801da177e4SLinus Torvalds if (error) 35811da177e4SLinus Torvalds return error; 35821da177e4SLinus Torvalds 3583acfa4380SAl Viro if (!dir->i_op->mkdir) 35841da177e4SLinus Torvalds return -EPERM; 35851da177e4SLinus Torvalds 35861da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35871da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35881da177e4SLinus Torvalds if (error) 35891da177e4SLinus Torvalds return error; 35901da177e4SLinus Torvalds 35918de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35928de52778SAl Viro return -EMLINK; 35938de52778SAl Viro 35941da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3595a74574aaSStephen Smalley if (!error) 3596f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35971da177e4SLinus Torvalds return error; 35981da177e4SLinus Torvalds } 35994d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36001da177e4SLinus Torvalds 3601a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36021da177e4SLinus Torvalds { 36036902d925SDave Hansen struct dentry *dentry; 3604dae6ad8fSAl Viro struct path path; 3605dae6ad8fSAl Viro int error; 3606b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36071da177e4SLinus Torvalds 3608b76d8b82SJeff Layton retry: 3609b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36106902d925SDave Hansen if (IS_ERR(dentry)) 3611dae6ad8fSAl Viro return PTR_ERR(dentry); 36126902d925SDave Hansen 3613dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3614ce3b0f8dSAl Viro mode &= ~current_umask(); 3615dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3616a8104a9fSAl Viro if (!error) 3617dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3618921a1650SAl Viro done_path_create(&path, dentry); 3619b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3620b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3621b76d8b82SJeff Layton goto retry; 3622b76d8b82SJeff Layton } 36231da177e4SLinus Torvalds return error; 36241da177e4SLinus Torvalds } 36251da177e4SLinus Torvalds 3626a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36275590ff0dSUlrich Drepper { 36285590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36295590ff0dSUlrich Drepper } 36305590ff0dSUlrich Drepper 36311da177e4SLinus Torvalds /* 3632a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3633c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3634a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3635a71905f0SSage Weil * then we drop the dentry now. 36361da177e4SLinus Torvalds * 36371da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36381da177e4SLinus Torvalds * do a 36391da177e4SLinus Torvalds * 36401da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36411da177e4SLinus Torvalds * return -EBUSY; 36421da177e4SLinus Torvalds * 36431da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36441da177e4SLinus Torvalds * that is still in use by something else.. 36451da177e4SLinus Torvalds */ 36461da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36471da177e4SLinus Torvalds { 36481da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36491da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 365098474236SWaiman Long if (dentry->d_lockref.count == 1) 36511da177e4SLinus Torvalds __d_drop(dentry); 36521da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36531da177e4SLinus Torvalds } 36544d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36551da177e4SLinus Torvalds 36561da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36571da177e4SLinus Torvalds { 36581da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36591da177e4SLinus Torvalds 36601da177e4SLinus Torvalds if (error) 36611da177e4SLinus Torvalds return error; 36621da177e4SLinus Torvalds 3663acfa4380SAl Viro if (!dir->i_op->rmdir) 36641da177e4SLinus Torvalds return -EPERM; 36651da177e4SLinus Torvalds 36661d2ef590SAl Viro dget(dentry); 36671b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3668912dbc15SSage Weil 36691da177e4SLinus Torvalds error = -EBUSY; 36707af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3671912dbc15SSage Weil goto out; 3672912dbc15SSage Weil 36731da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3674912dbc15SSage Weil if (error) 3675912dbc15SSage Weil goto out; 3676912dbc15SSage Weil 36773cebde24SSage Weil shrink_dcache_parent(dentry); 36781da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3679912dbc15SSage Weil if (error) 3680912dbc15SSage Weil goto out; 3681912dbc15SSage Weil 36821da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3683d83c49f3SAl Viro dont_mount(dentry); 36848ed936b5SEric W. Biederman detach_mounts(dentry); 36851da177e4SLinus Torvalds 3686912dbc15SSage Weil out: 3687912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36881d2ef590SAl Viro dput(dentry); 3689912dbc15SSage Weil if (!error) 3690912dbc15SSage Weil d_delete(dentry); 36911da177e4SLinus Torvalds return error; 36921da177e4SLinus Torvalds } 36934d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36941da177e4SLinus Torvalds 36955590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36961da177e4SLinus Torvalds { 36971da177e4SLinus Torvalds int error = 0; 369891a27b2aSJeff Layton struct filename *name; 36991da177e4SLinus Torvalds struct dentry *dentry; 3700f5beed75SAl Viro struct path path; 3701f5beed75SAl Viro struct qstr last; 3702f5beed75SAl Viro int type; 3703c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3704c6ee9206SJeff Layton retry: 3705f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3706f5beed75SAl Viro &path, &last, &type, lookup_flags); 370791a27b2aSJeff Layton if (IS_ERR(name)) 370891a27b2aSJeff Layton return PTR_ERR(name); 37091da177e4SLinus Torvalds 3710f5beed75SAl Viro switch (type) { 37111da177e4SLinus Torvalds case LAST_DOTDOT: 37121da177e4SLinus Torvalds error = -ENOTEMPTY; 37131da177e4SLinus Torvalds goto exit1; 37141da177e4SLinus Torvalds case LAST_DOT: 37151da177e4SLinus Torvalds error = -EINVAL; 37161da177e4SLinus Torvalds goto exit1; 37171da177e4SLinus Torvalds case LAST_ROOT: 37181da177e4SLinus Torvalds error = -EBUSY; 37191da177e4SLinus Torvalds goto exit1; 37201da177e4SLinus Torvalds } 37210612d9fbSOGAWA Hirofumi 3722f5beed75SAl Viro error = mnt_want_write(path.mnt); 3723c30dabfeSJan Kara if (error) 3724c30dabfeSJan Kara goto exit1; 37250612d9fbSOGAWA Hirofumi 3726f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3727f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37281da177e4SLinus Torvalds error = PTR_ERR(dentry); 37296902d925SDave Hansen if (IS_ERR(dentry)) 37306902d925SDave Hansen goto exit2; 3731e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3732e6bc45d6STheodore Ts'o error = -ENOENT; 3733e6bc45d6STheodore Ts'o goto exit3; 3734e6bc45d6STheodore Ts'o } 3735f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3736be6d3e56SKentaro Takeda if (error) 3737c30dabfeSJan Kara goto exit3; 3738f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37390622753bSDave Hansen exit3: 37401da177e4SLinus Torvalds dput(dentry); 37416902d925SDave Hansen exit2: 3742f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3743f5beed75SAl Viro mnt_drop_write(path.mnt); 37441da177e4SLinus Torvalds exit1: 3745f5beed75SAl Viro path_put(&path); 37461da177e4SLinus Torvalds putname(name); 3747c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3748c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3749c6ee9206SJeff Layton goto retry; 3750c6ee9206SJeff Layton } 37511da177e4SLinus Torvalds return error; 37521da177e4SLinus Torvalds } 37531da177e4SLinus Torvalds 37543cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37555590ff0dSUlrich Drepper { 37565590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37575590ff0dSUlrich Drepper } 37585590ff0dSUlrich Drepper 3759b21996e3SJ. Bruce Fields /** 3760b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3761b21996e3SJ. Bruce Fields * @dir: parent directory 3762b21996e3SJ. Bruce Fields * @dentry: victim 3763b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3764b21996e3SJ. Bruce Fields * 3765b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3766b21996e3SJ. Bruce Fields * 3767b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3768b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3769b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3770b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3771b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3772b21996e3SJ. Bruce Fields * 3773b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3774b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3775b21996e3SJ. Bruce Fields * to be NFS exported. 3776b21996e3SJ. Bruce Fields */ 3777b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37781da177e4SLinus Torvalds { 37799accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37801da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37811da177e4SLinus Torvalds 37821da177e4SLinus Torvalds if (error) 37831da177e4SLinus Torvalds return error; 37841da177e4SLinus Torvalds 3785acfa4380SAl Viro if (!dir->i_op->unlink) 37861da177e4SLinus Torvalds return -EPERM; 37871da177e4SLinus Torvalds 37889accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37898ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37901da177e4SLinus Torvalds error = -EBUSY; 37911da177e4SLinus Torvalds else { 37921da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3793bec1052eSAl Viro if (!error) { 37945a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37955a14696cSJ. Bruce Fields if (error) 3796b21996e3SJ. Bruce Fields goto out; 37971da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37988ed936b5SEric W. Biederman if (!error) { 3799d83c49f3SAl Viro dont_mount(dentry); 38008ed936b5SEric W. Biederman detach_mounts(dentry); 38018ed936b5SEric W. Biederman } 3802bec1052eSAl Viro } 38031da177e4SLinus Torvalds } 3804b21996e3SJ. Bruce Fields out: 38059accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 38061da177e4SLinus Torvalds 38071da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38081da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38099accbb97SJ. Bruce Fields fsnotify_link_count(target); 38101da177e4SLinus Torvalds d_delete(dentry); 38111da177e4SLinus Torvalds } 38120eeca283SRobert Love 38131da177e4SLinus Torvalds return error; 38141da177e4SLinus Torvalds } 38154d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38161da177e4SLinus Torvalds 38171da177e4SLinus Torvalds /* 38181da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38191b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38201da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38211da177e4SLinus Torvalds * while waiting on the I/O. 38221da177e4SLinus Torvalds */ 38235590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38241da177e4SLinus Torvalds { 38252ad94ae6SAl Viro int error; 382691a27b2aSJeff Layton struct filename *name; 38271da177e4SLinus Torvalds struct dentry *dentry; 3828f5beed75SAl Viro struct path path; 3829f5beed75SAl Viro struct qstr last; 3830f5beed75SAl Viro int type; 38311da177e4SLinus Torvalds struct inode *inode = NULL; 3832b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38335d18f813SJeff Layton unsigned int lookup_flags = 0; 38345d18f813SJeff Layton retry: 3835f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3836f5beed75SAl Viro &path, &last, &type, lookup_flags); 383791a27b2aSJeff Layton if (IS_ERR(name)) 383891a27b2aSJeff Layton return PTR_ERR(name); 38392ad94ae6SAl Viro 38401da177e4SLinus Torvalds error = -EISDIR; 3841f5beed75SAl Viro if (type != LAST_NORM) 38421da177e4SLinus Torvalds goto exit1; 38430612d9fbSOGAWA Hirofumi 3844f5beed75SAl Viro error = mnt_want_write(path.mnt); 3845c30dabfeSJan Kara if (error) 3846c30dabfeSJan Kara goto exit1; 3847b21996e3SJ. Bruce Fields retry_deleg: 3848f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3849f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38501da177e4SLinus Torvalds error = PTR_ERR(dentry); 38511da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38521da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3853f5beed75SAl Viro if (last.name[last.len]) 385450338b88STörök Edwin goto slashes; 38551da177e4SLinus Torvalds inode = dentry->d_inode; 3856b18825a7SDavid Howells if (d_is_negative(dentry)) 3857e6bc45d6STheodore Ts'o goto slashes; 38587de9c6eeSAl Viro ihold(inode); 3859f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3860be6d3e56SKentaro Takeda if (error) 3861c30dabfeSJan Kara goto exit2; 3862f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38631da177e4SLinus Torvalds exit2: 38641da177e4SLinus Torvalds dput(dentry); 38651da177e4SLinus Torvalds } 3866f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38671da177e4SLinus Torvalds if (inode) 38681da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3869b21996e3SJ. Bruce Fields inode = NULL; 3870b21996e3SJ. Bruce Fields if (delegated_inode) { 38715a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3872b21996e3SJ. Bruce Fields if (!error) 3873b21996e3SJ. Bruce Fields goto retry_deleg; 3874b21996e3SJ. Bruce Fields } 3875f5beed75SAl Viro mnt_drop_write(path.mnt); 38761da177e4SLinus Torvalds exit1: 3877f5beed75SAl Viro path_put(&path); 38781da177e4SLinus Torvalds putname(name); 38795d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38805d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38815d18f813SJeff Layton inode = NULL; 38825d18f813SJeff Layton goto retry; 38835d18f813SJeff Layton } 38841da177e4SLinus Torvalds return error; 38851da177e4SLinus Torvalds 38861da177e4SLinus Torvalds slashes: 3887b18825a7SDavid Howells if (d_is_negative(dentry)) 3888b18825a7SDavid Howells error = -ENOENT; 388944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3890b18825a7SDavid Howells error = -EISDIR; 3891b18825a7SDavid Howells else 3892b18825a7SDavid Howells error = -ENOTDIR; 38931da177e4SLinus Torvalds goto exit2; 38941da177e4SLinus Torvalds } 38951da177e4SLinus Torvalds 38962e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38975590ff0dSUlrich Drepper { 38985590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38995590ff0dSUlrich Drepper return -EINVAL; 39005590ff0dSUlrich Drepper 39015590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39025590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39035590ff0dSUlrich Drepper 39045590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 39055590ff0dSUlrich Drepper } 39065590ff0dSUlrich Drepper 39073480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39085590ff0dSUlrich Drepper { 39095590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 39105590ff0dSUlrich Drepper } 39115590ff0dSUlrich Drepper 3912db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39131da177e4SLinus Torvalds { 3914a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39151da177e4SLinus Torvalds 39161da177e4SLinus Torvalds if (error) 39171da177e4SLinus Torvalds return error; 39181da177e4SLinus Torvalds 3919acfa4380SAl Viro if (!dir->i_op->symlink) 39201da177e4SLinus Torvalds return -EPERM; 39211da177e4SLinus Torvalds 39221da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39231da177e4SLinus Torvalds if (error) 39241da177e4SLinus Torvalds return error; 39251da177e4SLinus Torvalds 39261da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3927a74574aaSStephen Smalley if (!error) 3928f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39291da177e4SLinus Torvalds return error; 39301da177e4SLinus Torvalds } 39314d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39321da177e4SLinus Torvalds 39332e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39342e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39351da177e4SLinus Torvalds { 39362ad94ae6SAl Viro int error; 393791a27b2aSJeff Layton struct filename *from; 39386902d925SDave Hansen struct dentry *dentry; 3939dae6ad8fSAl Viro struct path path; 3940f46d3567SJeff Layton unsigned int lookup_flags = 0; 39411da177e4SLinus Torvalds 39421da177e4SLinus Torvalds from = getname(oldname); 39431da177e4SLinus Torvalds if (IS_ERR(from)) 39441da177e4SLinus Torvalds return PTR_ERR(from); 3945f46d3567SJeff Layton retry: 3946f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39471da177e4SLinus Torvalds error = PTR_ERR(dentry); 39486902d925SDave Hansen if (IS_ERR(dentry)) 3949dae6ad8fSAl Viro goto out_putname; 39506902d925SDave Hansen 395191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3952a8104a9fSAl Viro if (!error) 395391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3954921a1650SAl Viro done_path_create(&path, dentry); 3955f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3956f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3957f46d3567SJeff Layton goto retry; 3958f46d3567SJeff Layton } 39596902d925SDave Hansen out_putname: 39601da177e4SLinus Torvalds putname(from); 39611da177e4SLinus Torvalds return error; 39621da177e4SLinus Torvalds } 39631da177e4SLinus Torvalds 39643480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39655590ff0dSUlrich Drepper { 39665590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39675590ff0dSUlrich Drepper } 39685590ff0dSUlrich Drepper 3969146a8595SJ. Bruce Fields /** 3970146a8595SJ. Bruce Fields * vfs_link - create a new link 3971146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3972146a8595SJ. Bruce Fields * @dir: new parent 3973146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3974146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3975146a8595SJ. Bruce Fields * 3976146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3977146a8595SJ. Bruce Fields * 3978146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3979146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3980146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3981146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3982146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3983146a8595SJ. Bruce Fields * 3984146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3985146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3986146a8595SJ. Bruce Fields * to be NFS exported. 3987146a8595SJ. Bruce Fields */ 3988146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39891da177e4SLinus Torvalds { 39901da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39918de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39921da177e4SLinus Torvalds int error; 39931da177e4SLinus Torvalds 39941da177e4SLinus Torvalds if (!inode) 39951da177e4SLinus Torvalds return -ENOENT; 39961da177e4SLinus Torvalds 3997a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39981da177e4SLinus Torvalds if (error) 39991da177e4SLinus Torvalds return error; 40001da177e4SLinus Torvalds 40011da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40021da177e4SLinus Torvalds return -EXDEV; 40031da177e4SLinus Torvalds 40041da177e4SLinus Torvalds /* 40051da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40061da177e4SLinus Torvalds */ 40071da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40081da177e4SLinus Torvalds return -EPERM; 4009acfa4380SAl Viro if (!dir->i_op->link) 40101da177e4SLinus Torvalds return -EPERM; 40117e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40121da177e4SLinus Torvalds return -EPERM; 40131da177e4SLinus Torvalds 40141da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40151da177e4SLinus Torvalds if (error) 40161da177e4SLinus Torvalds return error; 40171da177e4SLinus Torvalds 40187e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4019aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4020f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4021aae8a97dSAneesh Kumar K.V error = -ENOENT; 40228de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40238de52778SAl Viro error = -EMLINK; 4024146a8595SJ. Bruce Fields else { 4025146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4026146a8595SJ. Bruce Fields if (!error) 40271da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4028146a8595SJ. Bruce Fields } 4029f4e0c30cSAl Viro 4030f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4031f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4032f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4033f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4034f4e0c30cSAl Viro } 40357e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4036e31e14ecSStephen Smalley if (!error) 40377e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40381da177e4SLinus Torvalds return error; 40391da177e4SLinus Torvalds } 40404d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40411da177e4SLinus Torvalds 40421da177e4SLinus Torvalds /* 40431da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40441da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40451da177e4SLinus Torvalds * newname. --KAB 40461da177e4SLinus Torvalds * 40471da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40481da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40491da177e4SLinus Torvalds * and other special files. --ADM 40501da177e4SLinus Torvalds */ 40512e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40522e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40531da177e4SLinus Torvalds { 40541da177e4SLinus Torvalds struct dentry *new_dentry; 4055dae6ad8fSAl Viro struct path old_path, new_path; 4056146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 405711a7b371SAneesh Kumar K.V int how = 0; 40581da177e4SLinus Torvalds int error; 40591da177e4SLinus Torvalds 406011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4061c04030e1SUlrich Drepper return -EINVAL; 406211a7b371SAneesh Kumar K.V /* 4063f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4064f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4065f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 406611a7b371SAneesh Kumar K.V */ 4067f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4068f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4069f0cc6ffbSLinus Torvalds return -ENOENT; 407011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4071f0cc6ffbSLinus Torvalds } 4072c04030e1SUlrich Drepper 407311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 407411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4075442e31caSJeff Layton retry: 407611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40771da177e4SLinus Torvalds if (error) 40782ad94ae6SAl Viro return error; 40792ad94ae6SAl Viro 4080442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4081442e31caSJeff Layton (how & LOOKUP_REVAL)); 40821da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40836902d925SDave Hansen if (IS_ERR(new_dentry)) 4084dae6ad8fSAl Viro goto out; 4085dae6ad8fSAl Viro 4086dae6ad8fSAl Viro error = -EXDEV; 4087dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4088dae6ad8fSAl Viro goto out_dput; 4089800179c9SKees Cook error = may_linkat(&old_path); 4090800179c9SKees Cook if (unlikely(error)) 4091800179c9SKees Cook goto out_dput; 4092dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4093be6d3e56SKentaro Takeda if (error) 4094a8104a9fSAl Viro goto out_dput; 4095146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 409675c3f29dSDave Hansen out_dput: 4097921a1650SAl Viro done_path_create(&new_path, new_dentry); 4098146a8595SJ. Bruce Fields if (delegated_inode) { 4099146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4100d22e6338SOleg Drokin if (!error) { 4101d22e6338SOleg Drokin path_put(&old_path); 4102146a8595SJ. Bruce Fields goto retry; 4103146a8595SJ. Bruce Fields } 4104d22e6338SOleg Drokin } 4105442e31caSJeff Layton if (retry_estale(error, how)) { 4106d22e6338SOleg Drokin path_put(&old_path); 4107442e31caSJeff Layton how |= LOOKUP_REVAL; 4108442e31caSJeff Layton goto retry; 4109442e31caSJeff Layton } 41101da177e4SLinus Torvalds out: 41112d8f3038SAl Viro path_put(&old_path); 41121da177e4SLinus Torvalds 41131da177e4SLinus Torvalds return error; 41141da177e4SLinus Torvalds } 41151da177e4SLinus Torvalds 41163480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41175590ff0dSUlrich Drepper { 4118c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41195590ff0dSUlrich Drepper } 41205590ff0dSUlrich Drepper 4121bc27027aSMiklos Szeredi /** 4122bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4123bc27027aSMiklos Szeredi * @old_dir: parent of source 4124bc27027aSMiklos Szeredi * @old_dentry: source 4125bc27027aSMiklos Szeredi * @new_dir: parent of destination 4126bc27027aSMiklos Szeredi * @new_dentry: destination 4127bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4128520c8b16SMiklos Szeredi * @flags: rename flags 4129bc27027aSMiklos Szeredi * 4130bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4131bc27027aSMiklos Szeredi * 4132bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4133bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4134bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4135bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4136bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4137bc27027aSMiklos Szeredi * so. 4138bc27027aSMiklos Szeredi * 4139bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4140bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4141bc27027aSMiklos Szeredi * to be NFS exported. 4142bc27027aSMiklos Szeredi * 41431da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41441da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41451da177e4SLinus Torvalds * Problems: 4146d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41471da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41481da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4149a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41501da177e4SLinus Torvalds * story. 41516cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41526cedba89SJ. Bruce Fields * and source (if it is not a directory). 41531b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41541da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41551da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4156a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41571da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41581da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41591da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4160a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41611da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41621da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41631da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4164e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41651b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41661da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4167c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41681da177e4SLinus Torvalds * locking]. 41691da177e4SLinus Torvalds */ 41701da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41718e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4172520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41731da177e4SLinus Torvalds { 41741da177e4SLinus Torvalds int error; 4175bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 417659b0df21SEric Paris const unsigned char *old_name; 4177bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4178bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4179da1ce067SMiklos Szeredi bool new_is_dir = false; 4180da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41811da177e4SLinus Torvalds 4182bc27027aSMiklos Szeredi if (source == target) 41831da177e4SLinus Torvalds return 0; 41841da177e4SLinus Torvalds 41851da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41861da177e4SLinus Torvalds if (error) 41871da177e4SLinus Torvalds return error; 41881da177e4SLinus Torvalds 4189da1ce067SMiklos Szeredi if (!target) { 4190a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4191da1ce067SMiklos Szeredi } else { 4192da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4193da1ce067SMiklos Szeredi 4194da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41951da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4196da1ce067SMiklos Szeredi else 4197da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4198da1ce067SMiklos Szeredi } 41991da177e4SLinus Torvalds if (error) 42001da177e4SLinus Torvalds return error; 42011da177e4SLinus Torvalds 42027177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 42031da177e4SLinus Torvalds return -EPERM; 42041da177e4SLinus Torvalds 4205520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4206520c8b16SMiklos Szeredi return -EINVAL; 4207520c8b16SMiklos Szeredi 4208bc27027aSMiklos Szeredi /* 4209bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4210bc27027aSMiklos Szeredi * we'll need to flip '..'. 4211bc27027aSMiklos Szeredi */ 4212da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4213da1ce067SMiklos Szeredi if (is_dir) { 4214bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4215bc27027aSMiklos Szeredi if (error) 4216bc27027aSMiklos Szeredi return error; 4217bc27027aSMiklos Szeredi } 4218da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4219da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4220da1ce067SMiklos Szeredi if (error) 4221da1ce067SMiklos Szeredi return error; 4222da1ce067SMiklos Szeredi } 4223da1ce067SMiklos Szeredi } 42240eeca283SRobert Love 42250b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42260b3974ebSMiklos Szeredi flags); 4227bc27027aSMiklos Szeredi if (error) 4228bc27027aSMiklos Szeredi return error; 4229bc27027aSMiklos Szeredi 4230bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4231bc27027aSMiklos Szeredi dget(new_dentry); 4232da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4233bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4234bc27027aSMiklos Szeredi else if (target) 4235bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4236bc27027aSMiklos Szeredi 4237bc27027aSMiklos Szeredi error = -EBUSY; 42387af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4239bc27027aSMiklos Szeredi goto out; 4240bc27027aSMiklos Szeredi 4241da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4242bc27027aSMiklos Szeredi error = -EMLINK; 4243da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4244bc27027aSMiklos Szeredi goto out; 4245da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4246da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4247da1ce067SMiklos Szeredi goto out; 4248da1ce067SMiklos Szeredi } 4249da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4250bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4251da1ce067SMiklos Szeredi if (!is_dir) { 4252bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4253bc27027aSMiklos Szeredi if (error) 4254bc27027aSMiklos Szeredi goto out; 4255da1ce067SMiklos Szeredi } 4256da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4257bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4258bc27027aSMiklos Szeredi if (error) 4259bc27027aSMiklos Szeredi goto out; 4260bc27027aSMiklos Szeredi } 42617177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4262520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4263520c8b16SMiklos Szeredi new_dir, new_dentry); 4264520c8b16SMiklos Szeredi } else { 42657177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4266520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4267520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4268520c8b16SMiklos Szeredi } 4269bc27027aSMiklos Szeredi if (error) 4270bc27027aSMiklos Szeredi goto out; 4271bc27027aSMiklos Szeredi 4272da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42731da177e4SLinus Torvalds if (is_dir) 4274bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4275bc27027aSMiklos Szeredi dont_mount(new_dentry); 42768ed936b5SEric W. Biederman detach_mounts(new_dentry); 4277bc27027aSMiklos Szeredi } 4278da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4279da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4280bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4281da1ce067SMiklos Szeredi else 4282da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4283da1ce067SMiklos Szeredi } 4284bc27027aSMiklos Szeredi out: 4285da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4286bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4287bc27027aSMiklos Szeredi else if (target) 4288bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4289bc27027aSMiklos Szeredi dput(new_dentry); 4290da1ce067SMiklos Szeredi if (!error) { 4291123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4292da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4293da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4294da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4295da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4296da1ce067SMiklos Szeredi } 4297da1ce067SMiklos Szeredi } 42980eeca283SRobert Love fsnotify_oldname_free(old_name); 42990eeca283SRobert Love 43001da177e4SLinus Torvalds return error; 43011da177e4SLinus Torvalds } 43024d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43031da177e4SLinus Torvalds 4304520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4305520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 43061da177e4SLinus Torvalds { 43071da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43081da177e4SLinus Torvalds struct dentry *trap; 4309f5beed75SAl Viro struct path old_path, new_path; 4310f5beed75SAl Viro struct qstr old_last, new_last; 4311f5beed75SAl Viro int old_type, new_type; 43128e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 431391a27b2aSJeff Layton struct filename *from; 431491a27b2aSJeff Layton struct filename *to; 4315f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4316c6a94284SJeff Layton bool should_retry = false; 43172ad94ae6SAl Viro int error; 4318520c8b16SMiklos Szeredi 43190d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4320da1ce067SMiklos Szeredi return -EINVAL; 4321da1ce067SMiklos Szeredi 43220d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43230d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4324520c8b16SMiklos Szeredi return -EINVAL; 4325520c8b16SMiklos Szeredi 43260d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43270d7a8555SMiklos Szeredi return -EPERM; 43280d7a8555SMiklos Szeredi 4329f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4330f5beed75SAl Viro target_flags = 0; 4331f5beed75SAl Viro 4332c6a94284SJeff Layton retry: 4333f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4334f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 433591a27b2aSJeff Layton if (IS_ERR(from)) { 433691a27b2aSJeff Layton error = PTR_ERR(from); 43371da177e4SLinus Torvalds goto exit; 433891a27b2aSJeff Layton } 43391da177e4SLinus Torvalds 4340f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4341f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 434291a27b2aSJeff Layton if (IS_ERR(to)) { 434391a27b2aSJeff Layton error = PTR_ERR(to); 43441da177e4SLinus Torvalds goto exit1; 434591a27b2aSJeff Layton } 43461da177e4SLinus Torvalds 43471da177e4SLinus Torvalds error = -EXDEV; 4348f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43491da177e4SLinus Torvalds goto exit2; 43501da177e4SLinus Torvalds 43511da177e4SLinus Torvalds error = -EBUSY; 4352f5beed75SAl Viro if (old_type != LAST_NORM) 43531da177e4SLinus Torvalds goto exit2; 43541da177e4SLinus Torvalds 43550a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43560a7c3937SMiklos Szeredi error = -EEXIST; 4357f5beed75SAl Viro if (new_type != LAST_NORM) 43581da177e4SLinus Torvalds goto exit2; 43591da177e4SLinus Torvalds 4360f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4361c30dabfeSJan Kara if (error) 4362c30dabfeSJan Kara goto exit2; 4363c30dabfeSJan Kara 43648e6d782cSJ. Bruce Fields retry_deleg: 4365f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43661da177e4SLinus Torvalds 4367f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43681da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43691da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43701da177e4SLinus Torvalds goto exit3; 43711da177e4SLinus Torvalds /* source must exist */ 43721da177e4SLinus Torvalds error = -ENOENT; 4373b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43741da177e4SLinus Torvalds goto exit4; 4375f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43761da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43771da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43781da177e4SLinus Torvalds goto exit4; 43790a7c3937SMiklos Szeredi error = -EEXIST; 43800a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43810a7c3937SMiklos Szeredi goto exit5; 4382da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4383da1ce067SMiklos Szeredi error = -ENOENT; 4384da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4385da1ce067SMiklos Szeredi goto exit5; 4386da1ce067SMiklos Szeredi 4387da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4388da1ce067SMiklos Szeredi error = -ENOTDIR; 4389f5beed75SAl Viro if (new_last.name[new_last.len]) 4390da1ce067SMiklos Szeredi goto exit5; 4391da1ce067SMiklos Szeredi } 4392da1ce067SMiklos Szeredi } 43930a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43940a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43950a7c3937SMiklos Szeredi error = -ENOTDIR; 4396f5beed75SAl Viro if (old_last.name[old_last.len]) 43970a7c3937SMiklos Szeredi goto exit5; 4398f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43990a7c3937SMiklos Szeredi goto exit5; 44000a7c3937SMiklos Szeredi } 44010a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44020a7c3937SMiklos Szeredi error = -EINVAL; 44030a7c3937SMiklos Szeredi if (old_dentry == trap) 44040a7c3937SMiklos Szeredi goto exit5; 44051da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4406da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44071da177e4SLinus Torvalds error = -ENOTEMPTY; 44081da177e4SLinus Torvalds if (new_dentry == trap) 44091da177e4SLinus Torvalds goto exit5; 44101da177e4SLinus Torvalds 4411f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4412f5beed75SAl Viro &new_path, new_dentry, flags); 4413be6d3e56SKentaro Takeda if (error) 4414c30dabfeSJan Kara goto exit5; 4415f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4416f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4417520c8b16SMiklos Szeredi &delegated_inode, flags); 44181da177e4SLinus Torvalds exit5: 44191da177e4SLinus Torvalds dput(new_dentry); 44201da177e4SLinus Torvalds exit4: 44211da177e4SLinus Torvalds dput(old_dentry); 44221da177e4SLinus Torvalds exit3: 4423f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44248e6d782cSJ. Bruce Fields if (delegated_inode) { 44258e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44268e6d782cSJ. Bruce Fields if (!error) 44278e6d782cSJ. Bruce Fields goto retry_deleg; 44288e6d782cSJ. Bruce Fields } 4429f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44301da177e4SLinus Torvalds exit2: 4431c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4432c6a94284SJeff Layton should_retry = true; 4433f5beed75SAl Viro path_put(&new_path); 44342ad94ae6SAl Viro putname(to); 44351da177e4SLinus Torvalds exit1: 4436f5beed75SAl Viro path_put(&old_path); 44371da177e4SLinus Torvalds putname(from); 4438c6a94284SJeff Layton if (should_retry) { 4439c6a94284SJeff Layton should_retry = false; 4440c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4441c6a94284SJeff Layton goto retry; 4442c6a94284SJeff Layton } 44432ad94ae6SAl Viro exit: 44441da177e4SLinus Torvalds return error; 44451da177e4SLinus Torvalds } 44461da177e4SLinus Torvalds 4447520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4448520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4449520c8b16SMiklos Szeredi { 4450520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4451520c8b16SMiklos Szeredi } 4452520c8b16SMiklos Szeredi 4453a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44545590ff0dSUlrich Drepper { 4455520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44565590ff0dSUlrich Drepper } 44575590ff0dSUlrich Drepper 4458787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4459787fb6bcSMiklos Szeredi { 4460787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4461787fb6bcSMiklos Szeredi if (error) 4462787fb6bcSMiklos Szeredi return error; 4463787fb6bcSMiklos Szeredi 4464787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4465787fb6bcSMiklos Szeredi return -EPERM; 4466787fb6bcSMiklos Szeredi 4467787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4468787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4469787fb6bcSMiklos Szeredi } 4470787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4471787fb6bcSMiklos Szeredi 44725d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44731da177e4SLinus Torvalds { 44745d826c84SAl Viro int len = PTR_ERR(link); 44751da177e4SLinus Torvalds if (IS_ERR(link)) 44761da177e4SLinus Torvalds goto out; 44771da177e4SLinus Torvalds 44781da177e4SLinus Torvalds len = strlen(link); 44791da177e4SLinus Torvalds if (len > (unsigned) buflen) 44801da177e4SLinus Torvalds len = buflen; 44811da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44821da177e4SLinus Torvalds len = -EFAULT; 44831da177e4SLinus Torvalds out: 44841da177e4SLinus Torvalds return len; 44851da177e4SLinus Torvalds } 44865d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44871da177e4SLinus Torvalds 44881da177e4SLinus Torvalds /* 44891da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44901da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44911da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44921da177e4SLinus Torvalds */ 44931da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44941da177e4SLinus Torvalds { 4495cc314eefSLinus Torvalds void *cookie; 4496d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4497694a1764SMarcin Slusarz int res; 4498cc314eefSLinus Torvalds 4499d4dee48bSAl Viro if (!link) { 4500d4dee48bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); 4501680baacbSAl Viro if (IS_ERR(link)) 4502680baacbSAl Viro return PTR_ERR(link); 4503d4dee48bSAl Viro } 4504680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4505680baacbSAl Viro if (cookie && dentry->d_inode->i_op->put_link) 4506680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4507694a1764SMarcin Slusarz return res; 45081da177e4SLinus Torvalds } 45094d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 45101da177e4SLinus Torvalds 45111da177e4SLinus Torvalds /* get the link contents into pagecache */ 45121da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 45131da177e4SLinus Torvalds { 4514ebd09abbSDuane Griffin char *kaddr; 45151da177e4SLinus Torvalds struct page *page; 45161da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4517090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45181da177e4SLinus Torvalds if (IS_ERR(page)) 45196fe6900eSNick Piggin return (char*)page; 45201da177e4SLinus Torvalds *ppage = page; 4521ebd09abbSDuane Griffin kaddr = kmap(page); 4522ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4523ebd09abbSDuane Griffin return kaddr; 45241da177e4SLinus Torvalds } 45251da177e4SLinus Torvalds 45261da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45271da177e4SLinus Torvalds { 45281da177e4SLinus Torvalds struct page *page = NULL; 45295d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45301da177e4SLinus Torvalds if (page) { 45311da177e4SLinus Torvalds kunmap(page); 45321da177e4SLinus Torvalds page_cache_release(page); 45331da177e4SLinus Torvalds } 45341da177e4SLinus Torvalds return res; 45351da177e4SLinus Torvalds } 45364d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45371da177e4SLinus Torvalds 4538680baacbSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) 45391da177e4SLinus Torvalds { 4540cc314eefSLinus Torvalds struct page *page = NULL; 4541680baacbSAl Viro char *res = page_getlink(dentry, &page); 4542680baacbSAl Viro if (!IS_ERR(res)) 4543680baacbSAl Viro *cookie = page; 4544680baacbSAl Viro return res; 45451da177e4SLinus Torvalds } 45464d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45471da177e4SLinus Torvalds 4548680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45491da177e4SLinus Torvalds { 4550cc314eefSLinus Torvalds struct page *page = cookie; 45511da177e4SLinus Torvalds kunmap(page); 45521da177e4SLinus Torvalds page_cache_release(page); 45531da177e4SLinus Torvalds } 45544d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45551da177e4SLinus Torvalds 455654566b2cSNick Piggin /* 455754566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 455854566b2cSNick Piggin */ 455954566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45601da177e4SLinus Torvalds { 45611da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45620adb25d2SKirill Korotaev struct page *page; 4563afddba49SNick Piggin void *fsdata; 4564beb497abSDmitriy Monakhov int err; 45651da177e4SLinus Torvalds char *kaddr; 456654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 456754566b2cSNick Piggin if (nofs) 456854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45691da177e4SLinus Torvalds 45707e53cac4SNeilBrown retry: 4571afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 457254566b2cSNick Piggin flags, &page, &fsdata); 45731da177e4SLinus Torvalds if (err) 4574afddba49SNick Piggin goto fail; 4575afddba49SNick Piggin 4576e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45771da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4578e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4579afddba49SNick Piggin 4580afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4581afddba49SNick Piggin page, fsdata); 45821da177e4SLinus Torvalds if (err < 0) 45831da177e4SLinus Torvalds goto fail; 4584afddba49SNick Piggin if (err < len-1) 4585afddba49SNick Piggin goto retry; 4586afddba49SNick Piggin 45871da177e4SLinus Torvalds mark_inode_dirty(inode); 45881da177e4SLinus Torvalds return 0; 45891da177e4SLinus Torvalds fail: 45901da177e4SLinus Torvalds return err; 45911da177e4SLinus Torvalds } 45924d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45931da177e4SLinus Torvalds 45940adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45950adb25d2SKirill Korotaev { 45960adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 459754566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45980adb25d2SKirill Korotaev } 45994d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46000adb25d2SKirill Korotaev 460192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46021da177e4SLinus Torvalds .readlink = generic_readlink, 46031da177e4SLinus Torvalds .follow_link = page_follow_link_light, 46041da177e4SLinus Torvalds .put_link = page_put_link, 46051da177e4SLinus Torvalds }; 46061da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4607