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; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510237d8b32SAl Viro struct inode *inode; 5110450b2d1SAl Viro unsigned seq; 512894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5131f55a6ecSAl Viro }; 5141f55a6ecSAl Viro 515756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 516894bc8c4SAl Viro { 517756daf26SNeilBrown struct nameidata *old = current->nameidata; 518756daf26SNeilBrown p->stack = p->internal; 519756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 520756daf26SNeilBrown current->nameidata = p; 521756daf26SNeilBrown return old; 522894bc8c4SAl Viro } 523894bc8c4SAl Viro 524756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 525894bc8c4SAl Viro { 526756daf26SNeilBrown struct nameidata *now = current->nameidata; 527756daf26SNeilBrown 528756daf26SNeilBrown current->nameidata = old; 529756daf26SNeilBrown if (old) 530756daf26SNeilBrown old->total_link_count = now->total_link_count; 531756daf26SNeilBrown if (now->stack != now->internal) { 532756daf26SNeilBrown kfree(now->stack); 533756daf26SNeilBrown now->stack = now->internal; 534894bc8c4SAl Viro } 535894bc8c4SAl Viro } 536894bc8c4SAl Viro 537894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 538894bc8c4SAl Viro { 539e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 540894bc8c4SAl Viro GFP_KERNEL); 541894bc8c4SAl Viro if (unlikely(!p)) 542894bc8c4SAl Viro return -ENOMEM; 543894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 544894bc8c4SAl Viro nd->stack = p; 545894bc8c4SAl Viro return 0; 546894bc8c4SAl Viro } 547894bc8c4SAl Viro 548894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 549894bc8c4SAl Viro { 550da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 551894bc8c4SAl Viro return 0; 552894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 553894bc8c4SAl Viro return 0; 554894bc8c4SAl Viro return __nd_alloc_stack(nd); 555894bc8c4SAl Viro } 556894bc8c4SAl Viro 55719660af7SAl Viro /* 55831e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 55919660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 56019660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 56119660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 56219660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 56319660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 56419660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 56519660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 56631e6b01fSNick Piggin */ 56731e6b01fSNick Piggin 56831e6b01fSNick Piggin /** 56919660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 57019660af7SAl Viro * @nd: nameidata pathwalk data 57119660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 5726e9918b7SAl Viro * @seq: seq number to check dentry against 57339191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 57431e6b01fSNick Piggin * 57519660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 57619660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 57719660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 57831e6b01fSNick Piggin */ 5796e9918b7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) 58031e6b01fSNick Piggin { 58131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 58231e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 58331e6b01fSNick Piggin 58431e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 585e5c832d5SLinus Torvalds 586e5c832d5SLinus Torvalds /* 58748a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 58848a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 58948a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 59048a066e7SAl Viro * before returning. Do vfsmount first; if dentry 59148a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 59248a066e7SAl Viro * and rely on dput(NULL) being a no-op. 593e5c832d5SLinus Torvalds */ 59448a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 595e5c832d5SLinus Torvalds return -ECHILD; 596e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 59715570086SLinus Torvalds 59848a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 59948a066e7SAl Viro nd->path.dentry = NULL; 600d870b4a1SAl Viro goto out; 60148a066e7SAl Viro } 60248a066e7SAl Viro 60315570086SLinus Torvalds /* 60415570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 60515570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 60615570086SLinus Torvalds * 60715570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 60815570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 60915570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 61015570086SLinus Torvalds * since we checked the sequence number of the parent after we got 61115570086SLinus Torvalds * the child sequence number. So we know the parent must still 61215570086SLinus Torvalds * be valid if the child sequence number is still valid. 61315570086SLinus Torvalds */ 61419660af7SAl Viro if (!dentry) { 615e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 616e5c832d5SLinus Torvalds goto out; 61719660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 61819660af7SAl Viro } else { 619e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 620e5c832d5SLinus Torvalds goto out; 6216e9918b7SAl Viro if (read_seqcount_retry(&dentry->d_seq, seq)) 622e5c832d5SLinus Torvalds goto drop_dentry; 62319660af7SAl Viro } 624e5c832d5SLinus Torvalds 625e5c832d5SLinus Torvalds /* 626e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 627e5c832d5SLinus Torvalds * still valid and get it if required. 628e5c832d5SLinus Torvalds */ 629e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 630e5c832d5SLinus Torvalds spin_lock(&fs->lock); 631e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 632e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 63331e6b01fSNick Piggin path_get(&nd->root); 63431e6b01fSNick Piggin spin_unlock(&fs->lock); 63531e6b01fSNick Piggin } 63631e6b01fSNick Piggin 6378b61e74fSAl Viro rcu_read_unlock(); 63831e6b01fSNick Piggin return 0; 63919660af7SAl Viro 640e5c832d5SLinus Torvalds unlock_and_drop_dentry: 64131e6b01fSNick Piggin spin_unlock(&fs->lock); 642e5c832d5SLinus Torvalds drop_dentry: 6438b61e74fSAl Viro rcu_read_unlock(); 644e5c832d5SLinus Torvalds dput(dentry); 645d0d27277SLinus Torvalds goto drop_root_mnt; 646e5c832d5SLinus Torvalds out: 6478b61e74fSAl Viro rcu_read_unlock(); 648d0d27277SLinus Torvalds drop_root_mnt: 649d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 650d0d27277SLinus Torvalds nd->root.mnt = NULL; 65131e6b01fSNick Piggin return -ECHILD; 65231e6b01fSNick Piggin } 65331e6b01fSNick Piggin 6544ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 65534286d66SNick Piggin { 6564ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 65734286d66SNick Piggin } 65834286d66SNick Piggin 6599f1fafeeSAl Viro /** 6609f1fafeeSAl Viro * complete_walk - successful completion of path walk 6619f1fafeeSAl Viro * @nd: pointer nameidata 66239159de2SJeff Layton * 6639f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6649f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6659f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6669f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6679f1fafeeSAl Viro * need to drop nd->path. 66839159de2SJeff Layton */ 6699f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 67039159de2SJeff Layton { 67116c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 67239159de2SJeff Layton int status; 67339159de2SJeff Layton 6749f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6759f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6769f1fafeeSAl Viro nd->root.mnt = NULL; 6776e9918b7SAl Viro if (unlikely(unlazy_walk(nd, NULL, 0))) 67848a066e7SAl Viro return -ECHILD; 67948a066e7SAl Viro } 6809f1fafeeSAl Viro 68116c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 68239159de2SJeff Layton return 0; 68339159de2SJeff Layton 684ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 68516c2cd71SAl Viro return 0; 68616c2cd71SAl Viro 687ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 68839159de2SJeff Layton if (status > 0) 68939159de2SJeff Layton return 0; 69039159de2SJeff Layton 69116c2cd71SAl Viro if (!status) 69239159de2SJeff Layton status = -ESTALE; 69316c2cd71SAl Viro 69439159de2SJeff Layton return status; 69539159de2SJeff Layton } 69639159de2SJeff Layton 6972a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6982a737871SAl Viro { 699f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7002a737871SAl Viro } 7012a737871SAl Viro 7027bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 70331e6b01fSNick Piggin { 70431e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7057bd88377SAl Viro unsigned seq, res; 706c28cc364SNick Piggin 707c28cc364SNick Piggin do { 708c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 70931e6b01fSNick Piggin nd->root = fs->root; 7107bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 711c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7127bd88377SAl Viro return res; 71331e6b01fSNick Piggin } 71431e6b01fSNick Piggin 7151d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 716051d3812SIan Kent { 717051d3812SIan Kent dput(path->dentry); 7184ac91378SJan Blunck if (path->mnt != nd->path.mnt) 719051d3812SIan Kent mntput(path->mnt); 720051d3812SIan Kent } 721051d3812SIan Kent 7227b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7237b9337aaSNick Piggin struct nameidata *nd) 724051d3812SIan Kent { 72531e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7264ac91378SJan Blunck dput(nd->path.dentry); 72731e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7284ac91378SJan Blunck mntput(nd->path.mnt); 7299a229683SHuang Shijie } 73031e6b01fSNick Piggin nd->path.mnt = path->mnt; 7314ac91378SJan Blunck nd->path.dentry = path->dentry; 732051d3812SIan Kent } 733051d3812SIan Kent 734b5fb63c1SChristoph Hellwig /* 735b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 736b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 737b5fb63c1SChristoph Hellwig */ 7386e77137bSAl Viro void nd_jump_link(struct path *path) 739b5fb63c1SChristoph Hellwig { 7406e77137bSAl Viro struct nameidata *nd = current->nameidata; 741b5fb63c1SChristoph Hellwig path_put(&nd->path); 742b5fb63c1SChristoph Hellwig 743b5fb63c1SChristoph Hellwig nd->path = *path; 744b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 745b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 746b5fb63c1SChristoph Hellwig } 747b5fb63c1SChristoph Hellwig 748b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 749574197e0SAl Viro { 75021c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 751237d8b32SAl Viro struct inode *inode = last->inode; 752b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 7535f2c4179SAl Viro inode->i_op->put_link(inode, last->cookie); 7546548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 755b9ff4429SAl Viro path_put(&last->link); 756574197e0SAl Viro } 757574197e0SAl Viro 758561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 759561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 760800179c9SKees Cook 761800179c9SKees Cook /** 762800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 76355852635SRandy Dunlap * @nd: nameidata pathwalk data 764800179c9SKees Cook * 765800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 766800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 767800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 768800179c9SKees Cook * processes from failing races against path names that may change out 769800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 770800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 771800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 772800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 773800179c9SKees Cook * 774800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 775800179c9SKees Cook */ 776fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 777800179c9SKees Cook { 778800179c9SKees Cook const struct inode *inode; 779800179c9SKees Cook const struct inode *parent; 780800179c9SKees Cook 781800179c9SKees Cook if (!sysctl_protected_symlinks) 782800179c9SKees Cook return 0; 783800179c9SKees Cook 784800179c9SKees Cook /* Allowed if owner and follower match. */ 785237d8b32SAl Viro inode = nd->stack[0].inode; 78681abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 787800179c9SKees Cook return 0; 788800179c9SKees Cook 789800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 790800179c9SKees Cook parent = nd->path.dentry->d_inode; 791800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 792800179c9SKees Cook return 0; 793800179c9SKees Cook 794800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 79581abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 796800179c9SKees Cook return 0; 797800179c9SKees Cook 79831956502SAl Viro if (nd->flags & LOOKUP_RCU) 79931956502SAl Viro return -ECHILD; 80031956502SAl Viro 8011cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 802800179c9SKees Cook return -EACCES; 803800179c9SKees Cook } 804800179c9SKees Cook 805800179c9SKees Cook /** 806800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 807800179c9SKees Cook * @inode: the source inode to hardlink from 808800179c9SKees Cook * 809800179c9SKees Cook * Return false if at least one of the following conditions: 810800179c9SKees Cook * - inode is not a regular file 811800179c9SKees Cook * - inode is setuid 812800179c9SKees Cook * - inode is setgid and group-exec 813800179c9SKees Cook * - access failure for read and write 814800179c9SKees Cook * 815800179c9SKees Cook * Otherwise returns true. 816800179c9SKees Cook */ 817800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 818800179c9SKees Cook { 819800179c9SKees Cook umode_t mode = inode->i_mode; 820800179c9SKees Cook 821800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 822800179c9SKees Cook if (!S_ISREG(mode)) 823800179c9SKees Cook return false; 824800179c9SKees Cook 825800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 826800179c9SKees Cook if (mode & S_ISUID) 827800179c9SKees Cook return false; 828800179c9SKees Cook 829800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 830800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 831800179c9SKees Cook return false; 832800179c9SKees Cook 833800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 834800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 835800179c9SKees Cook return false; 836800179c9SKees Cook 837800179c9SKees Cook return true; 838800179c9SKees Cook } 839800179c9SKees Cook 840800179c9SKees Cook /** 841800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 842800179c9SKees Cook * @link: the source to hardlink from 843800179c9SKees Cook * 844800179c9SKees Cook * Block hardlink when all of: 845800179c9SKees Cook * - sysctl_protected_hardlinks enabled 846800179c9SKees Cook * - fsuid does not match inode 847800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 848800179c9SKees Cook * - not CAP_FOWNER 849800179c9SKees Cook * 850800179c9SKees Cook * Returns 0 if successful, -ve on error. 851800179c9SKees Cook */ 852800179c9SKees Cook static int may_linkat(struct path *link) 853800179c9SKees Cook { 854800179c9SKees Cook const struct cred *cred; 855800179c9SKees Cook struct inode *inode; 856800179c9SKees Cook 857800179c9SKees Cook if (!sysctl_protected_hardlinks) 858800179c9SKees Cook return 0; 859800179c9SKees Cook 860800179c9SKees Cook cred = current_cred(); 861800179c9SKees Cook inode = link->dentry->d_inode; 862800179c9SKees Cook 863800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 864800179c9SKees Cook * otherwise, it must be a safe source. 865800179c9SKees Cook */ 86681abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 867800179c9SKees Cook capable(CAP_FOWNER)) 868800179c9SKees Cook return 0; 869800179c9SKees Cook 870a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 871800179c9SKees Cook return -EPERM; 872800179c9SKees Cook } 873800179c9SKees Cook 8743b2e7f75SAl Viro static __always_inline 8753b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8761da177e4SLinus Torvalds { 877ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 8781cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 879237d8b32SAl Viro struct inode *inode = last->inode; 8806d7b5aaeSAl Viro int error; 8810a959df5SAl Viro const char *res; 8821da177e4SLinus Torvalds 883844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 884844a3917SAl Viro 885574197e0SAl Viro cond_resched(); 886574197e0SAl Viro 8873b2e7f75SAl Viro touch_atime(&last->link); 888cd4e91d3SAl Viro 889bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 890bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 891bda0be7aSNeilBrown if (unlikely(error)) 8926920a440SAl Viro return ERR_PTR(error); 89336f3b4f6SAl Viro 89486acdca1SAl Viro nd->last_type = LAST_BIND; 895d4dee48bSAl Viro res = inode->i_link; 896d4dee48bSAl Viro if (!res) { 8976e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 898fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 8996920a440SAl Viro last->cookie = NULL; 900fab51e8aSAl Viro return res; 9010a959df5SAl Viro } 902fab51e8aSAl Viro } 903fab51e8aSAl Viro if (*res == '/') { 904fab51e8aSAl Viro if (!nd->root.mnt) 905fab51e8aSAl Viro set_root(nd); 906fab51e8aSAl Viro path_put(&nd->path); 907fab51e8aSAl Viro nd->path = nd->root; 908fab51e8aSAl Viro path_get(&nd->root); 909fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 910fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 911fab51e8aSAl Viro while (unlikely(*++res == '/')) 912fab51e8aSAl Viro ; 913fab51e8aSAl Viro } 914fab51e8aSAl Viro if (!*res) 915fab51e8aSAl Viro res = NULL; 9160a959df5SAl Viro return res; 9170a959df5SAl Viro } 9186d7b5aaeSAl Viro 91931e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 92031e6b01fSNick Piggin { 9210714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9220714a533SAl Viro struct mount *parent; 92331e6b01fSNick Piggin struct dentry *mountpoint; 92431e6b01fSNick Piggin 9250714a533SAl Viro parent = mnt->mnt_parent; 9260714a533SAl Viro if (&parent->mnt == path->mnt) 92731e6b01fSNick Piggin return 0; 928a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 92931e6b01fSNick Piggin path->dentry = mountpoint; 9300714a533SAl Viro path->mnt = &parent->mnt; 93131e6b01fSNick Piggin return 1; 93231e6b01fSNick Piggin } 93331e6b01fSNick Piggin 934f015f126SDavid Howells /* 935f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 936f015f126SDavid Howells * 937f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 938f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 939f015f126SDavid Howells * Up is towards /. 940f015f126SDavid Howells * 941f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 942f015f126SDavid Howells * root. 943f015f126SDavid Howells */ 944bab77ebfSAl Viro int follow_up(struct path *path) 9451da177e4SLinus Torvalds { 9460714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9470714a533SAl Viro struct mount *parent; 9481da177e4SLinus Torvalds struct dentry *mountpoint; 94999b7db7bSNick Piggin 95048a066e7SAl Viro read_seqlock_excl(&mount_lock); 9510714a533SAl Viro parent = mnt->mnt_parent; 9523c0a6163SAl Viro if (parent == mnt) { 95348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9541da177e4SLinus Torvalds return 0; 9551da177e4SLinus Torvalds } 9560714a533SAl Viro mntget(&parent->mnt); 957a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 95848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 959bab77ebfSAl Viro dput(path->dentry); 960bab77ebfSAl Viro path->dentry = mountpoint; 961bab77ebfSAl Viro mntput(path->mnt); 9620714a533SAl Viro path->mnt = &parent->mnt; 9631da177e4SLinus Torvalds return 1; 9641da177e4SLinus Torvalds } 9654d359507SAl Viro EXPORT_SYMBOL(follow_up); 9661da177e4SLinus Torvalds 967b5c84bf6SNick Piggin /* 9689875cf80SDavid Howells * Perform an automount 9699875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9709875cf80SDavid Howells * were called with. 9711da177e4SLinus Torvalds */ 972756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 9739875cf80SDavid Howells bool *need_mntput) 97431e6b01fSNick Piggin { 9759875cf80SDavid Howells struct vfsmount *mnt; 976ea5b778aSDavid Howells int err; 9779875cf80SDavid Howells 9789875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9799875cf80SDavid Howells return -EREMOTE; 9809875cf80SDavid Howells 9810ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9820ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9830ec26fd0SMiklos Szeredi * the name. 9840ec26fd0SMiklos Szeredi * 9850ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9865a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9870ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9880ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9890ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9900ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9915a30d8a2SDavid Howells */ 992756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 993d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9945a30d8a2SDavid Howells path->dentry->d_inode) 9959875cf80SDavid Howells return -EISDIR; 9960ec26fd0SMiklos Szeredi 997756daf26SNeilBrown nd->total_link_count++; 998756daf26SNeilBrown if (nd->total_link_count >= 40) 9999875cf80SDavid Howells return -ELOOP; 10009875cf80SDavid Howells 10019875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10029875cf80SDavid Howells if (IS_ERR(mnt)) { 10039875cf80SDavid Howells /* 10049875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10059875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10069875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10079875cf80SDavid Howells * 10089875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10099875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10109875cf80SDavid Howells * the path is inaccessible and we should say so. 10119875cf80SDavid Howells */ 1012756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10139875cf80SDavid Howells return -EREMOTE; 10149875cf80SDavid Howells return PTR_ERR(mnt); 101531e6b01fSNick Piggin } 1016ea5b778aSDavid Howells 10179875cf80SDavid Howells if (!mnt) /* mount collision */ 10189875cf80SDavid Howells return 0; 10199875cf80SDavid Howells 10208aef1884SAl Viro if (!*need_mntput) { 10218aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10228aef1884SAl Viro mntget(path->mnt); 10238aef1884SAl Viro *need_mntput = true; 10248aef1884SAl Viro } 102519a167afSAl Viro err = finish_automount(mnt, path); 1026ea5b778aSDavid Howells 1027ea5b778aSDavid Howells switch (err) { 1028ea5b778aSDavid Howells case -EBUSY: 1029ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 103019a167afSAl Viro return 0; 1031ea5b778aSDavid Howells case 0: 10328aef1884SAl Viro path_put(path); 10339875cf80SDavid Howells path->mnt = mnt; 10349875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10359875cf80SDavid Howells return 0; 103619a167afSAl Viro default: 103719a167afSAl Viro return err; 10389875cf80SDavid Howells } 103919a167afSAl Viro 1040ea5b778aSDavid Howells } 10419875cf80SDavid Howells 10429875cf80SDavid Howells /* 10439875cf80SDavid Howells * Handle a dentry that is managed in some way. 1044cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10459875cf80SDavid Howells * - Flagged as mountpoint 10469875cf80SDavid Howells * - Flagged as automount point 10479875cf80SDavid Howells * 10489875cf80SDavid Howells * This may only be called in refwalk mode. 10499875cf80SDavid Howells * 10509875cf80SDavid Howells * Serialization is taken care of in namespace.c 10519875cf80SDavid Howells */ 1052756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 10539875cf80SDavid Howells { 10548aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10559875cf80SDavid Howells unsigned managed; 10569875cf80SDavid Howells bool need_mntput = false; 10578aef1884SAl Viro int ret = 0; 10589875cf80SDavid Howells 10599875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10609875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10619875cf80SDavid Howells * the components of that value change under us */ 10629875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10639875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10649875cf80SDavid Howells unlikely(managed != 0)) { 1065cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1066cc53ce53SDavid Howells * being held. */ 1067cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1068cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1069cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10701aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1071cc53ce53SDavid Howells if (ret < 0) 10728aef1884SAl Viro break; 1073cc53ce53SDavid Howells } 1074cc53ce53SDavid Howells 10759875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10769875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10779875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10789875cf80SDavid Howells if (mounted) { 10799875cf80SDavid Howells dput(path->dentry); 10809875cf80SDavid Howells if (need_mntput) 1081463ffb2eSAl Viro mntput(path->mnt); 1082463ffb2eSAl Viro path->mnt = mounted; 1083463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10849875cf80SDavid Howells need_mntput = true; 10859875cf80SDavid Howells continue; 1086463ffb2eSAl Viro } 1087463ffb2eSAl Viro 10889875cf80SDavid Howells /* Something is mounted on this dentry in another 10899875cf80SDavid Howells * namespace and/or whatever was mounted there in this 109048a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 109148a066e7SAl Viro * get it */ 10921da177e4SLinus Torvalds } 10939875cf80SDavid Howells 10949875cf80SDavid Howells /* Handle an automount point */ 10959875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1096756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 10979875cf80SDavid Howells if (ret < 0) 10988aef1884SAl Viro break; 10999875cf80SDavid Howells continue; 11009875cf80SDavid Howells } 11019875cf80SDavid Howells 11029875cf80SDavid Howells /* We didn't change the current path point */ 11039875cf80SDavid Howells break; 11049875cf80SDavid Howells } 11058aef1884SAl Viro 11068aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11078aef1884SAl Viro mntput(path->mnt); 11088aef1884SAl Viro if (ret == -EISDIR) 11098aef1884SAl Viro ret = 0; 11108402752eSAl Viro if (need_mntput) 11118402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11128402752eSAl Viro if (unlikely(ret < 0)) 11138402752eSAl Viro path_put_conditional(path, nd); 11148402752eSAl Viro return ret; 11151da177e4SLinus Torvalds } 11161da177e4SLinus Torvalds 1117cc53ce53SDavid Howells int follow_down_one(struct path *path) 11181da177e4SLinus Torvalds { 11191da177e4SLinus Torvalds struct vfsmount *mounted; 11201da177e4SLinus Torvalds 11211c755af4SAl Viro mounted = lookup_mnt(path); 11221da177e4SLinus Torvalds if (mounted) { 11239393bd07SAl Viro dput(path->dentry); 11249393bd07SAl Viro mntput(path->mnt); 11259393bd07SAl Viro path->mnt = mounted; 11269393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11271da177e4SLinus Torvalds return 1; 11281da177e4SLinus Torvalds } 11291da177e4SLinus Torvalds return 0; 11301da177e4SLinus Torvalds } 11314d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11321da177e4SLinus Torvalds 1133b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 113462a7375eSIan Kent { 1135b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1136b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 113762a7375eSIan Kent } 113862a7375eSIan Kent 11399875cf80SDavid Howells /* 1140287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1141287548e4SAl Viro * we meet a managed dentry that would need blocking. 11429875cf80SDavid Howells */ 11439875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1144254cf582SAl Viro struct inode **inode, unsigned *seqp) 11459875cf80SDavid Howells { 114662a7375eSIan Kent for (;;) { 1147c7105365SAl Viro struct mount *mounted; 114862a7375eSIan Kent /* 114962a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 115062a7375eSIan Kent * that wants to block transit. 115162a7375eSIan Kent */ 1152b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1153b8faf035SNeilBrown case -ECHILD: 1154b8faf035SNeilBrown default: 1155ab90911fSDavid Howells return false; 1156b8faf035SNeilBrown case -EISDIR: 1157b8faf035SNeilBrown return true; 1158b8faf035SNeilBrown case 0: 1159b8faf035SNeilBrown break; 1160b8faf035SNeilBrown } 116162a7375eSIan Kent 116262a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1163b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 116462a7375eSIan Kent 1165474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11669875cf80SDavid Howells if (!mounted) 11679875cf80SDavid Howells break; 1168c7105365SAl Viro path->mnt = &mounted->mnt; 1169c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1170a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1171254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 117259430262SLinus Torvalds /* 117359430262SLinus Torvalds * Update the inode too. We don't need to re-check the 117459430262SLinus Torvalds * dentry sequence number here after this d_inode read, 117559430262SLinus Torvalds * because a mount-point is always pinned. 117659430262SLinus Torvalds */ 117759430262SLinus Torvalds *inode = path->dentry->d_inode; 11789875cf80SDavid Howells } 1179f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1180b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1181287548e4SAl Viro } 1182287548e4SAl Viro 118331e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 118431e6b01fSNick Piggin { 11854023bfc9SAl Viro struct inode *inode = nd->inode; 11867bd88377SAl Viro if (!nd->root.mnt) 118731e6b01fSNick Piggin set_root_rcu(nd); 118831e6b01fSNick Piggin 118931e6b01fSNick Piggin while (1) { 119031e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 119131e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 119231e6b01fSNick Piggin break; 119331e6b01fSNick Piggin } 119431e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 119531e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 119631e6b01fSNick Piggin struct dentry *parent = old->d_parent; 119731e6b01fSNick Piggin unsigned seq; 119831e6b01fSNick Piggin 11994023bfc9SAl Viro inode = parent->d_inode; 120031e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 120131e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1202ef7562d5SAl Viro goto failed; 120331e6b01fSNick Piggin nd->path.dentry = parent; 120431e6b01fSNick Piggin nd->seq = seq; 120531e6b01fSNick Piggin break; 120631e6b01fSNick Piggin } 120731e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 120831e6b01fSNick Piggin break; 12094023bfc9SAl Viro inode = nd->path.dentry->d_inode; 121031e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 121131e6b01fSNick Piggin } 1212b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1213b37199e6SAl Viro struct mount *mounted; 1214b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1215b37199e6SAl Viro if (!mounted) 1216b37199e6SAl Viro break; 1217b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1218b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12194023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1220b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1221f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1222b37199e6SAl Viro goto failed; 1223b37199e6SAl Viro } 12244023bfc9SAl Viro nd->inode = inode; 122531e6b01fSNick Piggin return 0; 1226ef7562d5SAl Viro 1227ef7562d5SAl Viro failed: 1228ef7562d5SAl Viro return -ECHILD; 122931e6b01fSNick Piggin } 123031e6b01fSNick Piggin 12319875cf80SDavid Howells /* 1232cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1233cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1234cc53ce53SDavid Howells * caller is permitted to proceed or not. 1235cc53ce53SDavid Howells */ 12367cc90cc3SAl Viro int follow_down(struct path *path) 1237cc53ce53SDavid Howells { 1238cc53ce53SDavid Howells unsigned managed; 1239cc53ce53SDavid Howells int ret; 1240cc53ce53SDavid Howells 1241cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1242cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1243cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1244cc53ce53SDavid Howells * being held. 1245cc53ce53SDavid Howells * 1246cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1247cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1248cc53ce53SDavid Howells * other than its daemon the right to mount on its 1249cc53ce53SDavid Howells * superstructure. 1250cc53ce53SDavid Howells * 1251cc53ce53SDavid Howells * The filesystem may sleep at this point. 1252cc53ce53SDavid Howells */ 1253cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1254cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1255cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1256ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12571aed3e42SAl Viro path->dentry, false); 1258cc53ce53SDavid Howells if (ret < 0) 1259cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1260cc53ce53SDavid Howells } 1261cc53ce53SDavid Howells 1262cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1263cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1264cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1265cc53ce53SDavid Howells if (!mounted) 1266cc53ce53SDavid Howells break; 1267cc53ce53SDavid Howells dput(path->dentry); 1268cc53ce53SDavid Howells mntput(path->mnt); 1269cc53ce53SDavid Howells path->mnt = mounted; 1270cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1271cc53ce53SDavid Howells continue; 1272cc53ce53SDavid Howells } 1273cc53ce53SDavid Howells 1274cc53ce53SDavid Howells /* Don't handle automount points here */ 1275cc53ce53SDavid Howells break; 1276cc53ce53SDavid Howells } 1277cc53ce53SDavid Howells return 0; 1278cc53ce53SDavid Howells } 12794d359507SAl Viro EXPORT_SYMBOL(follow_down); 1280cc53ce53SDavid Howells 1281cc53ce53SDavid Howells /* 12829875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12839875cf80SDavid Howells */ 12849875cf80SDavid Howells static void follow_mount(struct path *path) 12859875cf80SDavid Howells { 12869875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12879875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12889875cf80SDavid Howells if (!mounted) 12899875cf80SDavid Howells break; 12909875cf80SDavid Howells dput(path->dentry); 12919875cf80SDavid Howells mntput(path->mnt); 12929875cf80SDavid Howells path->mnt = mounted; 12939875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12949875cf80SDavid Howells } 12959875cf80SDavid Howells } 12969875cf80SDavid Howells 129731e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12981da177e4SLinus Torvalds { 12997bd88377SAl Viro if (!nd->root.mnt) 13002a737871SAl Viro set_root(nd); 1301e518ddb7SAndreas Mohr 13021da177e4SLinus Torvalds while(1) { 13034ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13041da177e4SLinus Torvalds 13052a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13062a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13071da177e4SLinus Torvalds break; 13081da177e4SLinus Torvalds } 13094ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13103088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13113088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13121da177e4SLinus Torvalds dput(old); 13131da177e4SLinus Torvalds break; 13141da177e4SLinus Torvalds } 13153088dd70SAl Viro if (!follow_up(&nd->path)) 13161da177e4SLinus Torvalds break; 13171da177e4SLinus Torvalds } 131879ed0226SAl Viro follow_mount(&nd->path); 131931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13201da177e4SLinus Torvalds } 13211da177e4SLinus Torvalds 13221da177e4SLinus Torvalds /* 1323bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1324bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1325bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1326bad61189SMiklos Szeredi * 1327bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1328baa03890SNick Piggin */ 1329bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1330201f956eSAl Viro unsigned int flags, bool *need_lookup) 1331baa03890SNick Piggin { 1332baa03890SNick Piggin struct dentry *dentry; 1333bad61189SMiklos Szeredi int error; 1334baa03890SNick Piggin 1335bad61189SMiklos Szeredi *need_lookup = false; 1336bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1337bad61189SMiklos Szeredi if (dentry) { 133839e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1339201f956eSAl Viro error = d_revalidate(dentry, flags); 1340bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1341bad61189SMiklos Szeredi if (error < 0) { 1342bad61189SMiklos Szeredi dput(dentry); 1343bad61189SMiklos Szeredi return ERR_PTR(error); 13445542aa2fSEric W. Biederman } else { 13455542aa2fSEric W. Biederman d_invalidate(dentry); 1346bad61189SMiklos Szeredi dput(dentry); 1347bad61189SMiklos Szeredi dentry = NULL; 1348bad61189SMiklos Szeredi } 1349bad61189SMiklos Szeredi } 1350bad61189SMiklos Szeredi } 1351bad61189SMiklos Szeredi } 1352baa03890SNick Piggin 1353bad61189SMiklos Szeredi if (!dentry) { 1354bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1355baa03890SNick Piggin if (unlikely(!dentry)) 1356baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1357baa03890SNick Piggin 1358bad61189SMiklos Szeredi *need_lookup = true; 1359baa03890SNick Piggin } 1360baa03890SNick Piggin return dentry; 1361baa03890SNick Piggin } 1362baa03890SNick Piggin 1363baa03890SNick Piggin /* 136413a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 136513a2c3beSJ. Bruce Fields * unhashed. 1366bad61189SMiklos Szeredi * 1367bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 136844396f4bSJosef Bacik */ 1369bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 137072bd866aSAl Viro unsigned int flags) 137144396f4bSJosef Bacik { 137244396f4bSJosef Bacik struct dentry *old; 137344396f4bSJosef Bacik 137444396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1375bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1376e188dc02SMiklos Szeredi dput(dentry); 137744396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1378e188dc02SMiklos Szeredi } 137944396f4bSJosef Bacik 138072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 138144396f4bSJosef Bacik if (unlikely(old)) { 138244396f4bSJosef Bacik dput(dentry); 138344396f4bSJosef Bacik dentry = old; 138444396f4bSJosef Bacik } 138544396f4bSJosef Bacik return dentry; 138644396f4bSJosef Bacik } 138744396f4bSJosef Bacik 1388a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 138972bd866aSAl Viro struct dentry *base, unsigned int flags) 1390a3255546SAl Viro { 1391bad61189SMiklos Szeredi bool need_lookup; 1392a3255546SAl Viro struct dentry *dentry; 1393a3255546SAl Viro 139472bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1395bad61189SMiklos Szeredi if (!need_lookup) 1396a3255546SAl Viro return dentry; 1397bad61189SMiklos Szeredi 139872bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1399a3255546SAl Viro } 1400a3255546SAl Viro 140144396f4bSJosef Bacik /* 14021da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14031da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14041da177e4SLinus Torvalds * It _is_ time-critical. 14051da177e4SLinus Torvalds */ 1406e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1407254cf582SAl Viro struct path *path, struct inode **inode, 1408254cf582SAl Viro unsigned *seqp) 14091da177e4SLinus Torvalds { 14104ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 141131e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14125a18fff2SAl Viro int need_reval = 1; 14135a18fff2SAl Viro int status = 1; 14149875cf80SDavid Howells int err; 14159875cf80SDavid Howells 14163cac260aSAl Viro /* 1417b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1418b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1419b04f784eSNick Piggin * do the non-racy lookup, below. 1420b04f784eSNick Piggin */ 142131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 142231e6b01fSNick Piggin unsigned seq; 1423766c4cbfSAl Viro bool negative; 1424da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14255a18fff2SAl Viro if (!dentry) 14265a18fff2SAl Viro goto unlazy; 14275a18fff2SAl Viro 142812f8ad4bSLinus Torvalds /* 142912f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 143012f8ad4bSLinus Torvalds * the dentry name information from lookup. 143112f8ad4bSLinus Torvalds */ 143263afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1433766c4cbfSAl Viro negative = d_is_negative(dentry); 143412f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 143512f8ad4bSLinus Torvalds return -ECHILD; 1436766c4cbfSAl Viro if (negative) 1437766c4cbfSAl Viro return -ENOENT; 143812f8ad4bSLinus Torvalds 143912f8ad4bSLinus Torvalds /* 144012f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 144112f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 144212f8ad4bSLinus Torvalds * 144312f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 144412f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 144512f8ad4bSLinus Torvalds */ 144631e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 144731e6b01fSNick Piggin return -ECHILD; 14485a18fff2SAl Viro 1449254cf582SAl Viro *seqp = seq; 145024643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14514ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14525a18fff2SAl Viro if (unlikely(status <= 0)) { 14535a18fff2SAl Viro if (status != -ECHILD) 14545a18fff2SAl Viro need_reval = 0; 14555a18fff2SAl Viro goto unlazy; 14565a18fff2SAl Viro } 145724643087SAl Viro } 145831e6b01fSNick Piggin path->mnt = mnt; 145931e6b01fSNick Piggin path->dentry = dentry; 1460254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 14619875cf80SDavid Howells return 0; 14625a18fff2SAl Viro unlazy: 1463254cf582SAl Viro if (unlazy_walk(nd, dentry, seq)) 14645a18fff2SAl Viro return -ECHILD; 14655a18fff2SAl Viro } else { 1466e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 146724643087SAl Viro } 14685a18fff2SAl Viro 146981e6f520SAl Viro if (unlikely(!dentry)) 147081e6f520SAl Viro goto need_lookup; 14715a18fff2SAl Viro 14725a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14734ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14745a18fff2SAl Viro if (unlikely(status <= 0)) { 14755a18fff2SAl Viro if (status < 0) { 14765a18fff2SAl Viro dput(dentry); 14775a18fff2SAl Viro return status; 14785a18fff2SAl Viro } 14795542aa2fSEric W. Biederman d_invalidate(dentry); 14805a18fff2SAl Viro dput(dentry); 148181e6f520SAl Viro goto need_lookup; 14825a18fff2SAl Viro } 1483697f514dSMiklos Szeredi 1484766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1485766c4cbfSAl Viro dput(dentry); 1486766c4cbfSAl Viro return -ENOENT; 1487766c4cbfSAl Viro } 14881da177e4SLinus Torvalds path->mnt = mnt; 14891da177e4SLinus Torvalds path->dentry = dentry; 1490756daf26SNeilBrown err = follow_managed(path, nd); 14918402752eSAl Viro if (likely(!err)) 149263afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 14938402752eSAl Viro return err; 149481e6f520SAl Viro 149581e6f520SAl Viro need_lookup: 1496697f514dSMiklos Szeredi return 1; 1497697f514dSMiklos Szeredi } 1498697f514dSMiklos Szeredi 1499697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1500cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1501697f514dSMiklos Szeredi { 1502697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1503697f514dSMiklos Szeredi 1504697f514dSMiklos Szeredi parent = nd->path.dentry; 150581e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 150681e6f520SAl Viro 150781e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1508cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 150981e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 151081e6f520SAl Viro if (IS_ERR(dentry)) 151181e6f520SAl Viro return PTR_ERR(dentry); 1512697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1513697f514dSMiklos Szeredi path->dentry = dentry; 15148402752eSAl Viro return follow_managed(path, nd); 15151da177e4SLinus Torvalds } 15161da177e4SLinus Torvalds 151752094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 151852094c8aSAl Viro { 151952094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15204ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 152152094c8aSAl Viro if (err != -ECHILD) 152252094c8aSAl Viro return err; 15236e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 152452094c8aSAl Viro return -ECHILD; 152552094c8aSAl Viro } 15264ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 152752094c8aSAl Viro } 152852094c8aSAl Viro 15299856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15309856fa1bSAl Viro { 15319856fa1bSAl Viro if (type == LAST_DOTDOT) { 15329856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 153370291aecSAl Viro return follow_dotdot_rcu(nd); 15349856fa1bSAl Viro } else 15359856fa1bSAl Viro follow_dotdot(nd); 15369856fa1bSAl Viro } 15379856fa1bSAl Viro return 0; 15389856fa1bSAl Viro } 15399856fa1bSAl Viro 1540951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1541951361f9SAl Viro { 1542951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1543951361f9SAl Viro path_put(&nd->path); 1544951361f9SAl Viro } else { 1545951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15465b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1547951361f9SAl Viro nd->root.mnt = NULL; 15488b61e74fSAl Viro rcu_read_unlock(); 1549951361f9SAl Viro } 155015439726SAl Viro while (unlikely(nd->depth)) 155115439726SAl Viro put_link(nd); 1552951361f9SAl Viro } 1553951361f9SAl Viro 1554181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1555181548c0SAl Viro struct inode *inode, unsigned seq) 1556d63ff28fSAl Viro { 1557626de996SAl Viro int error; 15581cf2665bSAl Viro struct saved *last; 1559756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1560626de996SAl Viro path_to_nameidata(link, nd); 1561626de996SAl Viro return -ELOOP; 1562626de996SAl Viro } 1563d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1564d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1565254cf582SAl Viro unlazy_walk(nd, link->dentry, seq))) { 1566d63ff28fSAl Viro return -ECHILD; 1567d63ff28fSAl Viro } 1568d63ff28fSAl Viro } 1569cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1570cd179f44SAl Viro mntget(link->mnt); 1571626de996SAl Viro error = nd_alloc_stack(nd); 1572626de996SAl Viro if (unlikely(error)) { 1573cd179f44SAl Viro path_put(link); 1574626de996SAl Viro return error; 1575626de996SAl Viro } 1576626de996SAl Viro 1577ab104923SAl Viro last = nd->stack + nd->depth++; 15781cf2665bSAl Viro last->link = *link; 1579ab104923SAl Viro last->cookie = NULL; 1580181548c0SAl Viro last->inode = inode; 15810450b2d1SAl Viro last->seq = seq; 1582d63ff28fSAl Viro return 1; 1583d63ff28fSAl Viro } 1584d63ff28fSAl Viro 15853ddcd056SLinus Torvalds /* 15863ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15873ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15883ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15893ddcd056SLinus Torvalds * for the common case. 15903ddcd056SLinus Torvalds */ 1591254cf582SAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, 1592181548c0SAl Viro int follow, 1593181548c0SAl Viro struct inode *inode, unsigned seq) 15943ddcd056SLinus Torvalds { 1595d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1596d63ff28fSAl Viro return 0; 1597d63ff28fSAl Viro if (!follow) 1598d63ff28fSAl Viro return 0; 1599181548c0SAl Viro return pick_link(nd, link, inode, seq); 16003ddcd056SLinus Torvalds } 16013ddcd056SLinus Torvalds 16024693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 16034693a547SAl Viro 16044693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1605ce57dfc1SAl Viro { 1606caa85634SAl Viro struct path path; 1607ce57dfc1SAl Viro struct inode *inode; 1608254cf582SAl Viro unsigned seq; 1609ce57dfc1SAl Viro int err; 1610ce57dfc1SAl Viro /* 1611ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1612ce57dfc1SAl Viro * to be able to know about the current root directory and 1613ce57dfc1SAl Viro * parent relationships. 1614ce57dfc1SAl Viro */ 16154693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16164693a547SAl Viro err = handle_dots(nd, nd->last_type); 16174693a547SAl Viro if (flags & WALK_PUT) 16184693a547SAl Viro put_link(nd); 16194693a547SAl Viro return err; 16204693a547SAl Viro } 1621254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1622ce57dfc1SAl Viro if (unlikely(err)) { 1623697f514dSMiklos Szeredi if (err < 0) 1624f0a9ba70SAl Viro return err; 1625697f514dSMiklos Szeredi 1626caa85634SAl Viro err = lookup_slow(nd, &path); 1627697f514dSMiklos Szeredi if (err < 0) 1628f0a9ba70SAl Viro return err; 1629697f514dSMiklos Szeredi 163063afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 1631254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1632697f514dSMiklos Szeredi err = -ENOENT; 1633caa85634SAl Viro if (d_is_negative(path.dentry)) 1634697f514dSMiklos Szeredi goto out_path_put; 1635766c4cbfSAl Viro } 1636697f514dSMiklos Szeredi 16374693a547SAl Viro if (flags & WALK_PUT) 16384693a547SAl Viro put_link(nd); 1639181548c0SAl Viro err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); 1640d63ff28fSAl Viro if (unlikely(err)) 1641d63ff28fSAl Viro return err; 1642caa85634SAl Viro path_to_nameidata(&path, nd); 1643ce57dfc1SAl Viro nd->inode = inode; 1644254cf582SAl Viro nd->seq = seq; 1645ce57dfc1SAl Viro return 0; 1646697f514dSMiklos Szeredi 1647697f514dSMiklos Szeredi out_path_put: 1648caa85634SAl Viro path_to_nameidata(&path, nd); 1649697f514dSMiklos Szeredi return err; 1650ce57dfc1SAl Viro } 1651ce57dfc1SAl Viro 16521da177e4SLinus Torvalds /* 1653bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1654bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1655bfcfaa77SLinus Torvalds * 1656bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1657bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1658bfcfaa77SLinus Torvalds * fast. 1659bfcfaa77SLinus Torvalds * 1660bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1661bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1662bfcfaa77SLinus Torvalds * crossing operation. 1663bfcfaa77SLinus Torvalds * 1664bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1665bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1666bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1667bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1668bfcfaa77SLinus Torvalds */ 1669bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1670bfcfaa77SLinus Torvalds 1671f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1672bfcfaa77SLinus Torvalds 1673f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1674bfcfaa77SLinus Torvalds 1675bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1676bfcfaa77SLinus Torvalds { 167799d263d4SLinus Torvalds return hash_64(hash, 32); 1678bfcfaa77SLinus Torvalds } 1679bfcfaa77SLinus Torvalds 1680bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1681bfcfaa77SLinus Torvalds 1682bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1683bfcfaa77SLinus Torvalds 1684bfcfaa77SLinus Torvalds #endif 1685bfcfaa77SLinus Torvalds 1686bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1687bfcfaa77SLinus Torvalds { 1688bfcfaa77SLinus Torvalds unsigned long a, mask; 1689bfcfaa77SLinus Torvalds unsigned long hash = 0; 1690bfcfaa77SLinus Torvalds 1691bfcfaa77SLinus Torvalds for (;;) { 1692e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1693bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1694bfcfaa77SLinus Torvalds break; 1695bfcfaa77SLinus Torvalds hash += a; 1696f132c5beSAl Viro hash *= 9; 1697bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1698bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1699bfcfaa77SLinus Torvalds if (!len) 1700bfcfaa77SLinus Torvalds goto done; 1701bfcfaa77SLinus Torvalds } 1702a5c21dceSWill Deacon mask = bytemask_from_count(len); 1703bfcfaa77SLinus Torvalds hash += mask & a; 1704bfcfaa77SLinus Torvalds done: 1705bfcfaa77SLinus Torvalds return fold_hash(hash); 1706bfcfaa77SLinus Torvalds } 1707bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1708bfcfaa77SLinus Torvalds 1709bfcfaa77SLinus Torvalds /* 1710bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1711d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1712bfcfaa77SLinus Torvalds */ 1713d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1714bfcfaa77SLinus Torvalds { 171536126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 171636126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1717bfcfaa77SLinus Torvalds 1718bfcfaa77SLinus Torvalds hash = a = 0; 1719bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1720bfcfaa77SLinus Torvalds do { 1721bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1722bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1723e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 172436126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 172536126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1726bfcfaa77SLinus Torvalds 172736126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 172836126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 172936126f8fSLinus Torvalds 173036126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 173136126f8fSLinus Torvalds 173236126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17339226b5b4SLinus Torvalds len += find_zero(mask); 1734d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1735bfcfaa77SLinus Torvalds } 1736bfcfaa77SLinus Torvalds 1737bfcfaa77SLinus Torvalds #else 1738bfcfaa77SLinus Torvalds 17390145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17400145acc2SLinus Torvalds { 17410145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17420145acc2SLinus Torvalds while (len--) 17430145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17440145acc2SLinus Torvalds return end_name_hash(hash); 17450145acc2SLinus Torvalds } 1746ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17470145acc2SLinus Torvalds 17483ddcd056SLinus Torvalds /* 1749200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1750200e9ef7SLinus Torvalds * one character. 1751200e9ef7SLinus Torvalds */ 1752d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1753200e9ef7SLinus Torvalds { 1754200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1755200e9ef7SLinus Torvalds unsigned long len = 0, c; 1756200e9ef7SLinus Torvalds 1757200e9ef7SLinus Torvalds c = (unsigned char)*name; 1758200e9ef7SLinus Torvalds do { 1759200e9ef7SLinus Torvalds len++; 1760200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1761200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1762200e9ef7SLinus Torvalds } while (c && c != '/'); 1763d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1764200e9ef7SLinus Torvalds } 1765200e9ef7SLinus Torvalds 1766bfcfaa77SLinus Torvalds #endif 1767bfcfaa77SLinus Torvalds 1768200e9ef7SLinus Torvalds /* 17691da177e4SLinus Torvalds * Name resolution. 1770ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1771ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17721da177e4SLinus Torvalds * 1773ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1774ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17751da177e4SLinus Torvalds */ 17766de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17771da177e4SLinus Torvalds { 17781da177e4SLinus Torvalds int err; 17791da177e4SLinus Torvalds 17801da177e4SLinus Torvalds while (*name=='/') 17811da177e4SLinus Torvalds name++; 17821da177e4SLinus Torvalds if (!*name) 17839e18f10aSAl Viro return 0; 17841da177e4SLinus Torvalds 17851da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17861da177e4SLinus Torvalds for(;;) { 1787d6bb3e90SLinus Torvalds u64 hash_len; 1788fe479a58SAl Viro int type; 17891da177e4SLinus Torvalds 179052094c8aSAl Viro err = may_lookup(nd); 17911da177e4SLinus Torvalds if (err) 17923595e234SAl Viro return err; 17931da177e4SLinus Torvalds 1794d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17951da177e4SLinus Torvalds 1796fe479a58SAl Viro type = LAST_NORM; 1797d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1798fe479a58SAl Viro case 2: 1799200e9ef7SLinus Torvalds if (name[1] == '.') { 1800fe479a58SAl Viro type = LAST_DOTDOT; 180116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 180216c2cd71SAl Viro } 1803fe479a58SAl Viro break; 1804fe479a58SAl Viro case 1: 1805fe479a58SAl Viro type = LAST_DOT; 1806fe479a58SAl Viro } 18075a202bcdSAl Viro if (likely(type == LAST_NORM)) { 18085a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 180916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 18105a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1811a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1812da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 18135a202bcdSAl Viro if (err < 0) 18143595e234SAl Viro return err; 1815d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1816d6bb3e90SLinus Torvalds name = this.name; 18175a202bcdSAl Viro } 18185a202bcdSAl Viro } 1819fe479a58SAl Viro 1820d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1821d6bb3e90SLinus Torvalds nd->last.name = name; 18225f4a6a69SAl Viro nd->last_type = type; 18235f4a6a69SAl Viro 1824d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1825d6bb3e90SLinus Torvalds if (!*name) 1826bdf6cbf1SAl Viro goto OK; 1827200e9ef7SLinus Torvalds /* 1828200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1829200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1830200e9ef7SLinus Torvalds */ 1831200e9ef7SLinus Torvalds do { 1832d6bb3e90SLinus Torvalds name++; 1833d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 18348620c238SAl Viro if (unlikely(!*name)) { 18358620c238SAl Viro OK: 1836368ee9baSAl Viro /* pathname body, done */ 18378620c238SAl Viro if (!nd->depth) 18388620c238SAl Viro return 0; 18398620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1840368ee9baSAl Viro /* trailing symlink, done */ 18418620c238SAl Viro if (!name) 18428620c238SAl Viro return 0; 18438620c238SAl Viro /* last component of nested symlink */ 18444693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18458620c238SAl Viro } else { 18464693a547SAl Viro err = walk_component(nd, WALK_GET); 18478620c238SAl Viro } 1848ce57dfc1SAl Viro if (err < 0) 18493595e234SAl Viro return err; 1850fe479a58SAl Viro 1851ce57dfc1SAl Viro if (err) { 1852626de996SAl Viro const char *s = get_link(nd); 18535a460275SAl Viro 18543595e234SAl Viro if (unlikely(IS_ERR(s))) 18553595e234SAl Viro return PTR_ERR(s); 1856172a39a0SAl Viro err = 0; 185712b09578SAl Viro if (unlikely(!s)) { 185812b09578SAl Viro /* jumped */ 1859b9ff4429SAl Viro put_link(nd); 186012b09578SAl Viro } else { 1861071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 186232cd7468SAl Viro name = s; 18639e18f10aSAl Viro continue; 186448c8b0c5SAl Viro } 186531e6b01fSNick Piggin } 18663595e234SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) 18673595e234SAl Viro return -ENOTDIR; 18685f4a6a69SAl Viro } 1869ce57dfc1SAl Viro } 18701da177e4SLinus Torvalds 1871368ee9baSAl Viro static const char *path_init(int dfd, const struct filename *name, 1872368ee9baSAl Viro unsigned int flags, struct nameidata *nd) 187331e6b01fSNick Piggin { 187431e6b01fSNick Piggin int retval = 0; 1875fd2f7cb5SAl Viro const char *s = name->name; 187631e6b01fSNick Piggin 187731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1878980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 187931e6b01fSNick Piggin nd->depth = 0; 1880368ee9baSAl Viro nd->total_link_count = 0; 18815b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1882b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1883b18825a7SDavid Howells struct inode *inode = root->d_inode; 1884fd2f7cb5SAl Viro if (*s) { 188544b1d530SMiklos Szeredi if (!d_can_lookup(root)) 1886368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 18875b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18885b6ca027SAl Viro if (retval) 1889368ee9baSAl Viro return ERR_PTR(retval); 189073d049a4SAl Viro } 18915b6ca027SAl Viro nd->path = nd->root; 18925b6ca027SAl Viro nd->inode = inode; 18935b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18948b61e74fSAl Viro rcu_read_lock(); 18955b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 189648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18975b6ca027SAl Viro } else { 18985b6ca027SAl Viro path_get(&nd->path); 18995b6ca027SAl Viro } 1900368ee9baSAl Viro return s; 19015b6ca027SAl Viro } 19025b6ca027SAl Viro 190331e6b01fSNick Piggin nd->root.mnt = NULL; 190431e6b01fSNick Piggin 190548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1906fd2f7cb5SAl Viro if (*s == '/') { 1907e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19088b61e74fSAl Viro rcu_read_lock(); 19097bd88377SAl Viro nd->seq = set_root_rcu(nd); 1910e41f7d4eSAl Viro } else { 1911e41f7d4eSAl Viro set_root(nd); 1912e41f7d4eSAl Viro path_get(&nd->root); 1913e41f7d4eSAl Viro } 191431e6b01fSNick Piggin nd->path = nd->root; 191531e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1916e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 191731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1918c28cc364SNick Piggin unsigned seq; 191931e6b01fSNick Piggin 19208b61e74fSAl Viro rcu_read_lock(); 192131e6b01fSNick Piggin 1922c28cc364SNick Piggin do { 1923c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 192431e6b01fSNick Piggin nd->path = fs->pwd; 1925c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1926c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1927e41f7d4eSAl Viro } else { 1928e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1929e41f7d4eSAl Viro } 193031e6b01fSNick Piggin } else { 1931582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19322903ff01SAl Viro struct fd f = fdget_raw(dfd); 193331e6b01fSNick Piggin struct dentry *dentry; 193431e6b01fSNick Piggin 19352903ff01SAl Viro if (!f.file) 1936368ee9baSAl Viro return ERR_PTR(-EBADF); 193731e6b01fSNick Piggin 19382903ff01SAl Viro dentry = f.file->f_path.dentry; 193931e6b01fSNick Piggin 1940fd2f7cb5SAl Viro if (*s) { 194144b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19422903ff01SAl Viro fdput(f); 1943368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 1944f52e0c11SAl Viro } 19452903ff01SAl Viro } 19462903ff01SAl Viro 19472903ff01SAl Viro nd->path = f.file->f_path; 1948e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19498b61e74fSAl Viro rcu_read_lock(); 195034a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 195134a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 19525590ff0dSUlrich Drepper } else { 19532903ff01SAl Viro path_get(&nd->path); 195434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 19551da177e4SLinus Torvalds } 195634a26b99SAl Viro fdput(f); 1957368ee9baSAl Viro return s; 1958e41f7d4eSAl Viro } 1959e41f7d4eSAl Viro 196031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19614023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1962368ee9baSAl Viro return s; 19634023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1964368ee9baSAl Viro return s; 19654023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19664023bfc9SAl Viro nd->root.mnt = NULL; 19674023bfc9SAl Viro rcu_read_unlock(); 1968368ee9baSAl Viro return ERR_PTR(-ECHILD); 19699b4a9b14SAl Viro } 19709b4a9b14SAl Viro 1971893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1972893b7775SAl Viro { 1973893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1974893b7775SAl Viro path_put(&nd->root); 1975893b7775SAl Viro nd->root.mnt = NULL; 1976893b7775SAl Viro } 19779b4a9b14SAl Viro } 19789b4a9b14SAl Viro 19793bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 198095fa25d9SAl Viro { 198195fa25d9SAl Viro const char *s; 1982fec2fa24SAl Viro int error = may_follow_link(nd); 1983deb106c6SAl Viro if (unlikely(error)) 19843bdba28bSAl Viro return ERR_PTR(error); 198595fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 1986fab51e8aSAl Viro nd->stack[0].name = NULL; 19873b2e7f75SAl Viro s = get_link(nd); 1988deb106c6SAl Viro return s ? s : ""; 198995fa25d9SAl Viro } 199095fa25d9SAl Viro 1991caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 1992bd92d7feSAl Viro { 1993bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1994bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1995bd92d7feSAl Viro 1996bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1997deb106c6SAl Viro return walk_component(nd, 19984693a547SAl Viro nd->flags & LOOKUP_FOLLOW 19994693a547SAl Viro ? nd->depth 20004693a547SAl Viro ? WALK_PUT | WALK_GET 20014693a547SAl Viro : WALK_GET 20024693a547SAl Viro : 0); 2003bd92d7feSAl Viro } 2004bd92d7feSAl Viro 20059b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20065eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20079b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20089b4a9b14SAl Viro { 2009368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2010bd92d7feSAl Viro int err; 201131e6b01fSNick Piggin 2012368ee9baSAl Viro if (IS_ERR(s)) 2013368ee9baSAl Viro return PTR_ERR(s); 20143bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 20153bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 20163bdba28bSAl Viro s = trailing_symlink(nd); 20173bdba28bSAl Viro if (IS_ERR(s)) { 20183bdba28bSAl Viro err = PTR_ERR(s); 20196d7b5aaeSAl Viro break; 2020bd92d7feSAl Viro } 2021bd92d7feSAl Viro } 20229f1fafeeSAl Viro if (!err) 20239f1fafeeSAl Viro err = complete_walk(nd); 2024bd92d7feSAl Viro 2025deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2026deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2027bd23a539SAl Viro err = -ENOTDIR; 2028deb106c6SAl Viro if (err) 2029deb106c6SAl Viro terminate_walk(nd); 203016c2cd71SAl Viro 2031893b7775SAl Viro path_cleanup(nd); 2032bd92d7feSAl Viro return err; 203331e6b01fSNick Piggin } 203431e6b01fSNick Piggin 2035873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2036873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2037873f1eedSJeff Layton { 2038894bc8c4SAl Viro int retval; 2039756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2040894bc8c4SAl Viro 2041894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2042873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20435eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2044873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20455eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2046873f1eedSJeff Layton 2047873f1eedSJeff Layton if (likely(!retval)) 2048adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2049756daf26SNeilBrown restore_nameidata(saved_nd); 2050873f1eedSJeff Layton return retval; 2051873f1eedSJeff Layton } 2052873f1eedSJeff Layton 20538bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20548bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 20558bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20568bcb77faSAl Viro { 2057368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2058368ee9baSAl Viro int err; 2059368ee9baSAl Viro if (IS_ERR(s)) 2060368ee9baSAl Viro return PTR_ERR(s); 2061368ee9baSAl Viro err = link_path_walk(s, nd); 20628bcb77faSAl Viro if (!err) 20638bcb77faSAl Viro err = complete_walk(nd); 2064deb106c6SAl Viro if (err) 2065deb106c6SAl Viro terminate_walk(nd); 20668bcb77faSAl Viro path_cleanup(nd); 20678bcb77faSAl Viro return err; 20688bcb77faSAl Viro } 20698bcb77faSAl Viro 20708bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 20718bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20728bcb77faSAl Viro { 20738bcb77faSAl Viro int retval; 20748bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 20758bcb77faSAl Viro 20768bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 20778bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 20788bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 20798bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 20808bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 20818bcb77faSAl Viro 20828bcb77faSAl Viro if (likely(!retval)) 20838bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 20848bcb77faSAl Viro restore_nameidata(saved_nd); 20858bcb77faSAl Viro return retval; 20868bcb77faSAl Viro } 20878bcb77faSAl Viro 208879714f72SAl Viro /* does lookup, returns the object with parent locked */ 208979714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20905590ff0dSUlrich Drepper { 209151689104SPaul Moore struct filename *filename = getname_kernel(name); 209279714f72SAl Viro struct nameidata nd; 209379714f72SAl Viro struct dentry *d; 209451689104SPaul Moore int err; 209551689104SPaul Moore 209651689104SPaul Moore if (IS_ERR(filename)) 209751689104SPaul Moore return ERR_CAST(filename); 209851689104SPaul Moore 20998bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 210051689104SPaul Moore if (err) { 210151689104SPaul Moore d = ERR_PTR(err); 210251689104SPaul Moore goto out; 210351689104SPaul Moore } 210479714f72SAl Viro if (nd.last_type != LAST_NORM) { 210579714f72SAl Viro path_put(&nd.path); 210651689104SPaul Moore d = ERR_PTR(-EINVAL); 210751689104SPaul Moore goto out; 210879714f72SAl Viro } 210979714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21101e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 211179714f72SAl Viro if (IS_ERR(d)) { 211279714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 211379714f72SAl Viro path_put(&nd.path); 211451689104SPaul Moore goto out; 211579714f72SAl Viro } 211679714f72SAl Viro *path = nd.path; 211751689104SPaul Moore out: 211851689104SPaul Moore putname(filename); 211979714f72SAl Viro return d; 21205590ff0dSUlrich Drepper } 21215590ff0dSUlrich Drepper 2122d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2123d1811465SAl Viro { 2124d1811465SAl Viro struct nameidata nd; 212574eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 212674eb8cc5SAl Viro int res = PTR_ERR(filename); 212774eb8cc5SAl Viro 212874eb8cc5SAl Viro if (!IS_ERR(filename)) { 212974eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 213074eb8cc5SAl Viro putname(filename); 2131d1811465SAl Viro if (!res) 2132d1811465SAl Viro *path = nd.path; 213374eb8cc5SAl Viro } 2134d1811465SAl Viro return res; 2135d1811465SAl Viro } 21364d359507SAl Viro EXPORT_SYMBOL(kern_path); 2137d1811465SAl Viro 213816f18200SJosef 'Jeff' Sipek /** 213916f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 214016f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 214116f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 214216f18200SJosef 'Jeff' Sipek * @name: pointer to file name 214316f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2144e0a01249SAl Viro * @path: pointer to struct path to fill 214516f18200SJosef 'Jeff' Sipek */ 214616f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 214716f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2148e0a01249SAl Viro struct path *path) 214916f18200SJosef 'Jeff' Sipek { 215074eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 215174eb8cc5SAl Viro int err = PTR_ERR(filename); 215274eb8cc5SAl Viro 215374eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 215474eb8cc5SAl Viro 215574eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 215674eb8cc5SAl Viro if (!IS_ERR(filename)) { 2157e0a01249SAl Viro struct nameidata nd; 2158e0a01249SAl Viro nd.root.dentry = dentry; 2159e0a01249SAl Viro nd.root.mnt = mnt; 216074eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 216174eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2162e0a01249SAl Viro if (!err) 2163e0a01249SAl Viro *path = nd.path; 216474eb8cc5SAl Viro putname(filename); 216574eb8cc5SAl Viro } 2166e0a01249SAl Viro return err; 216716f18200SJosef 'Jeff' Sipek } 21684d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 216916f18200SJosef 'Jeff' Sipek 2170eead1911SChristoph Hellwig /** 2171a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2172eead1911SChristoph Hellwig * @name: pathname component to lookup 2173eead1911SChristoph Hellwig * @base: base directory to lookup from 2174eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2175eead1911SChristoph Hellwig * 2176a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21779e7543e9SAl Viro * not be called by generic code. 2178eead1911SChristoph Hellwig */ 2179057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2180057f6c01SJames Morris { 2181057f6c01SJames Morris struct qstr this; 21826a96ba54SAl Viro unsigned int c; 2183cda309deSMiklos Szeredi int err; 2184057f6c01SJames Morris 21852f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21862f9092e1SDavid Woodhouse 21876a96ba54SAl Viro this.name = name; 21886a96ba54SAl Viro this.len = len; 21890145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21906a96ba54SAl Viro if (!len) 21916a96ba54SAl Viro return ERR_PTR(-EACCES); 21926a96ba54SAl Viro 219321d8a15aSAl Viro if (unlikely(name[0] == '.')) { 219421d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 219521d8a15aSAl Viro return ERR_PTR(-EACCES); 219621d8a15aSAl Viro } 219721d8a15aSAl Viro 21986a96ba54SAl Viro while (len--) { 21996a96ba54SAl Viro c = *(const unsigned char *)name++; 22006a96ba54SAl Viro if (c == '/' || c == '\0') 22016a96ba54SAl Viro return ERR_PTR(-EACCES); 22026a96ba54SAl Viro } 22035a202bcdSAl Viro /* 22045a202bcdSAl Viro * See if the low-level filesystem might want 22055a202bcdSAl Viro * to use its own hash.. 22065a202bcdSAl Viro */ 22075a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2208da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22095a202bcdSAl Viro if (err < 0) 22105a202bcdSAl Viro return ERR_PTR(err); 22115a202bcdSAl Viro } 2212eead1911SChristoph Hellwig 2213cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2214cda309deSMiklos Szeredi if (err) 2215cda309deSMiklos Szeredi return ERR_PTR(err); 2216cda309deSMiklos Szeredi 221772bd866aSAl Viro return __lookup_hash(&this, base, 0); 2218057f6c01SJames Morris } 22194d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2220057f6c01SJames Morris 22211fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22221fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22231da177e4SLinus Torvalds { 22242d8f3038SAl Viro struct nameidata nd; 222591a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22261da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22271da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22282d8f3038SAl Viro 22292d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22302d8f3038SAl Viro 2231873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22321da177e4SLinus Torvalds putname(tmp); 22332d8f3038SAl Viro if (!err) 22342d8f3038SAl Viro *path = nd.path; 22351da177e4SLinus Torvalds } 22361da177e4SLinus Torvalds return err; 22371da177e4SLinus Torvalds } 22381da177e4SLinus Torvalds 22391fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22401fa1e7f6SAndy Whitcroft struct path *path) 22411fa1e7f6SAndy Whitcroft { 2242f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22431fa1e7f6SAndy Whitcroft } 22444d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22451fa1e7f6SAndy Whitcroft 2246873f1eedSJeff Layton /* 2247873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2248873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2249873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2250873f1eedSJeff Layton * path-walking is complete. 2251873f1eedSJeff Layton */ 225291a27b2aSJeff Layton static struct filename * 2253f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2254f5beed75SAl Viro struct path *parent, 2255f5beed75SAl Viro struct qstr *last, 2256f5beed75SAl Viro int *type, 22579e790bd6SJeff Layton unsigned int flags) 22582ad94ae6SAl Viro { 2259f5beed75SAl Viro struct nameidata nd; 226091a27b2aSJeff Layton struct filename *s = getname(path); 22612ad94ae6SAl Viro int error; 22622ad94ae6SAl Viro 22639e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22649e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22659e790bd6SJeff Layton 22662ad94ae6SAl Viro if (IS_ERR(s)) 226791a27b2aSJeff Layton return s; 22682ad94ae6SAl Viro 22698bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 227091a27b2aSJeff Layton if (error) { 22712ad94ae6SAl Viro putname(s); 227291a27b2aSJeff Layton return ERR_PTR(error); 227391a27b2aSJeff Layton } 2274f5beed75SAl Viro *parent = nd.path; 2275f5beed75SAl Viro *last = nd.last; 2276f5beed75SAl Viro *type = nd.last_type; 22772ad94ae6SAl Viro 227891a27b2aSJeff Layton return s; 22792ad94ae6SAl Viro } 22802ad94ae6SAl Viro 22818033426eSJeff Layton /** 2282197df04cSAl Viro * mountpoint_last - look up last component for umount 22838033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22848033426eSJeff Layton * @path: pointer to container for result 22858033426eSJeff Layton * 22868033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22878033426eSJeff Layton * need to resolve the path without doing any revalidation. 22888033426eSJeff Layton * 22898033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22908033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22918033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22928033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22938033426eSJeff Layton * bogus and it doesn't exist. 22948033426eSJeff Layton * 22958033426eSJeff Layton * Returns: 22968033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22978033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22988033426eSJeff Layton * put in this case. 22998033426eSJeff Layton * 23008033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23018033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23028033426eSJeff Layton * The nd->path reference will also be put. 23038033426eSJeff Layton * 23048033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23058033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23068033426eSJeff Layton * to the link, and nd->path will *not* be put. 23078033426eSJeff Layton */ 23088033426eSJeff Layton static int 2309197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23108033426eSJeff Layton { 23118033426eSJeff Layton int error = 0; 23128033426eSJeff Layton struct dentry *dentry; 23138033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23148033426eSJeff Layton 231535759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 231635759521SAl Viro if (nd->flags & LOOKUP_RCU) { 23176e9918b7SAl Viro if (unlazy_walk(nd, NULL, 0)) 2318deb106c6SAl Viro return -ECHILD; 23198033426eSJeff Layton } 23208033426eSJeff Layton 23218033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23228033426eSJeff Layton 23238033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23248033426eSJeff Layton error = handle_dots(nd, nd->last_type); 232535759521SAl Viro if (error) 2326deb106c6SAl Viro return error; 23278033426eSJeff Layton dentry = dget(nd->path.dentry); 232835759521SAl Viro goto done; 23298033426eSJeff Layton } 23308033426eSJeff Layton 23318033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23328033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23338033426eSJeff Layton if (!dentry) { 23348033426eSJeff Layton /* 23358033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23368033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23378033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23388033426eSJeff Layton */ 23398033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23408033426eSJeff Layton if (!dentry) { 2341bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2342deb106c6SAl Viro return -ENOMEM; 23438033426eSJeff Layton } 234435759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2345bcceeebaSDave Jones if (IS_ERR(dentry)) { 2346bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2347deb106c6SAl Viro return PTR_ERR(dentry); 23488033426eSJeff Layton } 2349bcceeebaSDave Jones } 23508033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23518033426eSJeff Layton 235235759521SAl Viro done: 2353698934dfSDavid Howells if (d_is_negative(dentry)) { 23548033426eSJeff Layton dput(dentry); 2355deb106c6SAl Viro return -ENOENT; 235635759521SAl Viro } 2357191d7f73SAl Viro if (nd->depth) 2358191d7f73SAl Viro put_link(nd); 23598033426eSJeff Layton path->dentry = dentry; 2360295dc39dSVasily Averin path->mnt = nd->path.mnt; 2361181548c0SAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, 2362181548c0SAl Viro d_backing_inode(dentry), 0); 2363deb106c6SAl Viro if (unlikely(error)) 2364d63ff28fSAl Viro return error; 2365295dc39dSVasily Averin mntget(path->mnt); 23668033426eSJeff Layton follow_mount(path); 2367deb106c6SAl Viro return 0; 23688033426eSJeff Layton } 23698033426eSJeff Layton 23708033426eSJeff Layton /** 2371197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23728033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23738033426eSJeff Layton * @name: full pathname to walk 2374606d6fe3SRandy Dunlap * @path: pointer to container for result 23758033426eSJeff Layton * @flags: lookup flags 23768033426eSJeff Layton * 23778033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2378606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23798033426eSJeff Layton */ 23808033426eSJeff Layton static int 2381668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 238246afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 23838033426eSJeff Layton { 2384368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2385368ee9baSAl Viro int err; 2386368ee9baSAl Viro if (IS_ERR(s)) 2387368ee9baSAl Viro return PTR_ERR(s); 23883bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 23893bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 23903bdba28bSAl Viro s = trailing_symlink(nd); 23913bdba28bSAl Viro if (IS_ERR(s)) { 23923bdba28bSAl Viro err = PTR_ERR(s); 23938033426eSJeff Layton break; 23948033426eSJeff Layton } 23953bdba28bSAl Viro } 2396deb106c6SAl Viro terminate_walk(nd); 239746afd6f6SAl Viro path_cleanup(nd); 23988033426eSJeff Layton return err; 23998033426eSJeff Layton } 24008033426eSJeff Layton 24012d864651SAl Viro static int 2402668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24032d864651SAl Viro unsigned int flags) 24042d864651SAl Viro { 2405756daf26SNeilBrown struct nameidata nd, *saved; 2406cbaab2dbSAl Viro int error; 2407668696dcSAl Viro if (IS_ERR(name)) 2408668696dcSAl Viro return PTR_ERR(name); 2409756daf26SNeilBrown saved = set_nameidata(&nd); 241046afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24112d864651SAl Viro if (unlikely(error == -ECHILD)) 241246afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24132d864651SAl Viro if (unlikely(error == -ESTALE)) 241446afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24152d864651SAl Viro if (likely(!error)) 2416668696dcSAl Viro audit_inode(name, path->dentry, 0); 2417756daf26SNeilBrown restore_nameidata(saved); 2418668696dcSAl Viro putname(name); 24192d864651SAl Viro return error; 24202d864651SAl Viro } 24212d864651SAl Viro 24228033426eSJeff Layton /** 2423197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24248033426eSJeff Layton * @dfd: directory file descriptor 24258033426eSJeff Layton * @name: pathname from userland 24268033426eSJeff Layton * @flags: lookup flags 24278033426eSJeff Layton * @path: pointer to container to hold result 24288033426eSJeff Layton * 24298033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24308033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24318033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24328033426eSJeff Layton * and avoid revalidating the last component. 24338033426eSJeff Layton * 24348033426eSJeff Layton * Returns 0 and populates "path" on success. 24358033426eSJeff Layton */ 24368033426eSJeff Layton int 2437197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24388033426eSJeff Layton struct path *path) 24398033426eSJeff Layton { 2440cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24418033426eSJeff Layton } 24428033426eSJeff Layton 24432d864651SAl Viro int 24442d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24452d864651SAl Viro unsigned int flags) 24462d864651SAl Viro { 2447cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24482d864651SAl Viro } 24492d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24502d864651SAl Viro 2451cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24521da177e4SLinus Torvalds { 24538e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2454da9592edSDavid Howells 24558e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24561da177e4SLinus Torvalds return 0; 24578e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24581da177e4SLinus Torvalds return 0; 245923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24601da177e4SLinus Torvalds } 2461cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24621da177e4SLinus Torvalds 24631da177e4SLinus Torvalds /* 24641da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24651da177e4SLinus Torvalds * whether the type of victim is right. 24661da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24671da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24681da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24691da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24701da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24711da177e4SLinus Torvalds * a. be owner of dir, or 24721da177e4SLinus Torvalds * b. be owner of victim, or 24731da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24741da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24751da177e4SLinus Torvalds * links pointing to it. 24761da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24771da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24781da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24791da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24801da177e4SLinus Torvalds * nfs_async_unlink(). 24811da177e4SLinus Torvalds */ 2482b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24831da177e4SLinus Torvalds { 248463afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 24851da177e4SLinus Torvalds int error; 24861da177e4SLinus Torvalds 2487b18825a7SDavid Howells if (d_is_negative(victim)) 24881da177e4SLinus Torvalds return -ENOENT; 2489b18825a7SDavid Howells BUG_ON(!inode); 24901da177e4SLinus Torvalds 24911da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24924fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24931da177e4SLinus Torvalds 2494f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24951da177e4SLinus Torvalds if (error) 24961da177e4SLinus Torvalds return error; 24971da177e4SLinus Torvalds if (IS_APPEND(dir)) 24981da177e4SLinus Torvalds return -EPERM; 2499b18825a7SDavid Howells 2500b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2501b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25021da177e4SLinus Torvalds return -EPERM; 25031da177e4SLinus Torvalds if (isdir) { 250444b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25051da177e4SLinus Torvalds return -ENOTDIR; 25061da177e4SLinus Torvalds if (IS_ROOT(victim)) 25071da177e4SLinus Torvalds return -EBUSY; 250844b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25091da177e4SLinus Torvalds return -EISDIR; 25101da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25111da177e4SLinus Torvalds return -ENOENT; 25121da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25131da177e4SLinus Torvalds return -EBUSY; 25141da177e4SLinus Torvalds return 0; 25151da177e4SLinus Torvalds } 25161da177e4SLinus Torvalds 25171da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25181da177e4SLinus Torvalds * dir. 25191da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25201da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25211da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25221da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25231da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25241da177e4SLinus Torvalds */ 2525a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25261da177e4SLinus Torvalds { 252714e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25281da177e4SLinus Torvalds if (child->d_inode) 25291da177e4SLinus Torvalds return -EEXIST; 25301da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25311da177e4SLinus Torvalds return -ENOENT; 2532f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25331da177e4SLinus Torvalds } 25341da177e4SLinus Torvalds 25351da177e4SLinus Torvalds /* 25361da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25371da177e4SLinus Torvalds */ 25381da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25391da177e4SLinus Torvalds { 25401da177e4SLinus Torvalds struct dentry *p; 25411da177e4SLinus Torvalds 25421da177e4SLinus Torvalds if (p1 == p2) { 2543f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25441da177e4SLinus Torvalds return NULL; 25451da177e4SLinus Torvalds } 25461da177e4SLinus Torvalds 2547a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25481da177e4SLinus Torvalds 2549e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2550e2761a11SOGAWA Hirofumi if (p) { 2551f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2552f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25531da177e4SLinus Torvalds return p; 25541da177e4SLinus Torvalds } 25551da177e4SLinus Torvalds 2556e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2557e2761a11SOGAWA Hirofumi if (p) { 2558f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2559f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25601da177e4SLinus Torvalds return p; 25611da177e4SLinus Torvalds } 25621da177e4SLinus Torvalds 2563f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2564d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25651da177e4SLinus Torvalds return NULL; 25661da177e4SLinus Torvalds } 25674d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25681da177e4SLinus Torvalds 25691da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25701da177e4SLinus Torvalds { 25711b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25721da177e4SLinus Torvalds if (p1 != p2) { 25731b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2574a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25751da177e4SLinus Torvalds } 25761da177e4SLinus Torvalds } 25774d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25781da177e4SLinus Torvalds 25794acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2580312b63fbSAl Viro bool want_excl) 25811da177e4SLinus Torvalds { 2582a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25831da177e4SLinus Torvalds if (error) 25841da177e4SLinus Torvalds return error; 25851da177e4SLinus Torvalds 2586acfa4380SAl Viro if (!dir->i_op->create) 25871da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25881da177e4SLinus Torvalds mode &= S_IALLUGO; 25891da177e4SLinus Torvalds mode |= S_IFREG; 25901da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25911da177e4SLinus Torvalds if (error) 25921da177e4SLinus Torvalds return error; 2593312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2594a74574aaSStephen Smalley if (!error) 2595f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25961da177e4SLinus Torvalds return error; 25971da177e4SLinus Torvalds } 25984d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25991da177e4SLinus Torvalds 260073d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26011da177e4SLinus Torvalds { 26023fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26031da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26041da177e4SLinus Torvalds int error; 26051da177e4SLinus Torvalds 2606bcda7652SAl Viro /* O_PATH? */ 2607bcda7652SAl Viro if (!acc_mode) 2608bcda7652SAl Viro return 0; 2609bcda7652SAl Viro 26101da177e4SLinus Torvalds if (!inode) 26111da177e4SLinus Torvalds return -ENOENT; 26121da177e4SLinus Torvalds 2613c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2614c8fe8f30SChristoph Hellwig case S_IFLNK: 26151da177e4SLinus Torvalds return -ELOOP; 2616c8fe8f30SChristoph Hellwig case S_IFDIR: 2617c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26181da177e4SLinus Torvalds return -EISDIR; 2619c8fe8f30SChristoph Hellwig break; 2620c8fe8f30SChristoph Hellwig case S_IFBLK: 2621c8fe8f30SChristoph Hellwig case S_IFCHR: 26223fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26231da177e4SLinus Torvalds return -EACCES; 2624c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2625c8fe8f30SChristoph Hellwig case S_IFIFO: 2626c8fe8f30SChristoph Hellwig case S_IFSOCK: 26271da177e4SLinus Torvalds flag &= ~O_TRUNC; 2628c8fe8f30SChristoph Hellwig break; 26294a3fd211SDave Hansen } 2630b41572e9SDave Hansen 26313fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2632b41572e9SDave Hansen if (error) 2633b41572e9SDave Hansen return error; 26346146f0d5SMimi Zohar 26351da177e4SLinus Torvalds /* 26361da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26371da177e4SLinus Torvalds */ 26381da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26398737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26407715b521SAl Viro return -EPERM; 26411da177e4SLinus Torvalds if (flag & O_TRUNC) 26427715b521SAl Viro return -EPERM; 26431da177e4SLinus Torvalds } 26441da177e4SLinus Torvalds 26451da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26462e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26477715b521SAl Viro return -EPERM; 26481da177e4SLinus Torvalds 2649f3c7691eSJ. Bruce Fields return 0; 26507715b521SAl Viro } 26517715b521SAl Viro 2652e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26537715b521SAl Viro { 2654e1181ee6SJeff Layton struct path *path = &filp->f_path; 26557715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26567715b521SAl Viro int error = get_write_access(inode); 26571da177e4SLinus Torvalds if (error) 26587715b521SAl Viro return error; 26591da177e4SLinus Torvalds /* 26601da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26611da177e4SLinus Torvalds */ 2662d7a06983SJeff Layton error = locks_verify_locked(filp); 2663be6d3e56SKentaro Takeda if (!error) 2664ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26651da177e4SLinus Torvalds if (!error) { 26667715b521SAl Viro error = do_truncate(path->dentry, 0, 2667d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2668e1181ee6SJeff Layton filp); 26691da177e4SLinus Torvalds } 26701da177e4SLinus Torvalds put_write_access(inode); 2671acd0c935SMimi Zohar return error; 26721da177e4SLinus Torvalds } 26731da177e4SLinus Torvalds 2674d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2675d57999e1SDave Hansen { 26768a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26778a5e929dSAl Viro flag--; 2678d57999e1SDave Hansen return flag; 2679d57999e1SDave Hansen } 2680d57999e1SDave Hansen 2681d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2682d18e9008SMiklos Szeredi { 2683d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2684d18e9008SMiklos Szeredi if (error) 2685d18e9008SMiklos Szeredi return error; 2686d18e9008SMiklos Szeredi 2687d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2688d18e9008SMiklos Szeredi if (error) 2689d18e9008SMiklos Szeredi return error; 2690d18e9008SMiklos Szeredi 2691d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2692d18e9008SMiklos Szeredi } 2693d18e9008SMiklos Szeredi 26941acf0af9SDavid Howells /* 26951acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26961acf0af9SDavid Howells * dentry. 26971acf0af9SDavid Howells * 26981acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26991acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27001acf0af9SDavid Howells * 27011acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27021acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27031acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27041acf0af9SDavid Howells * 27051acf0af9SDavid Howells * Returns an error code otherwise. 27061acf0af9SDavid Howells */ 27072675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 270830d90494SAl Viro struct path *path, struct file *file, 2709015c3bbcSMiklos Szeredi const struct open_flags *op, 271064894cf8SAl Viro bool got_write, bool need_lookup, 271147237687SAl Viro int *opened) 2712d18e9008SMiklos Szeredi { 2713d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2714d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2715d18e9008SMiklos Szeredi umode_t mode; 2716d18e9008SMiklos Szeredi int error; 2717d18e9008SMiklos Szeredi int acc_mode; 2718d18e9008SMiklos Szeredi int create_error = 0; 2719d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2720116cc022SMiklos Szeredi bool excl; 2721d18e9008SMiklos Szeredi 2722d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2723d18e9008SMiklos Szeredi 2724d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2725d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27262675a4ebSAl Viro error = -ENOENT; 2727d18e9008SMiklos Szeredi goto out; 2728d18e9008SMiklos Szeredi } 2729d18e9008SMiklos Szeredi 273062b259d8SMiklos Szeredi mode = op->mode; 2731d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2732d18e9008SMiklos Szeredi mode &= ~current_umask(); 2733d18e9008SMiklos Szeredi 2734116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2735116cc022SMiklos Szeredi if (excl) 2736d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2737d18e9008SMiklos Szeredi 2738d18e9008SMiklos Szeredi /* 2739d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2740d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2741d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2742d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2743d18e9008SMiklos Szeredi * 2744d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2745d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2746d18e9008SMiklos Szeredi */ 274764894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 274864894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 274964894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2750d18e9008SMiklos Szeredi /* 2751d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2752d18e9008SMiklos Szeredi * back to lookup + open 2753d18e9008SMiklos Szeredi */ 2754d18e9008SMiklos Szeredi goto no_open; 2755d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2756d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 275764894cf8SAl Viro create_error = -EROFS; 2758d18e9008SMiklos Szeredi goto no_open; 2759d18e9008SMiklos Szeredi } else { 2760d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 276164894cf8SAl Viro create_error = -EROFS; 2762d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2763d18e9008SMiklos Szeredi } 2764d18e9008SMiklos Szeredi } 2765d18e9008SMiklos Szeredi 2766d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 276738227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2768d18e9008SMiklos Szeredi if (error) { 2769d18e9008SMiklos Szeredi create_error = error; 2770d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2771d18e9008SMiklos Szeredi goto no_open; 2772d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2773d18e9008SMiklos Szeredi } 2774d18e9008SMiklos Szeredi } 2775d18e9008SMiklos Szeredi 2776d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2777d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2778d18e9008SMiklos Szeredi 277930d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 278030d90494SAl Viro file->f_path.mnt = nd->path.mnt; 278130d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 278247237687SAl Viro opened); 2783d9585277SAl Viro if (error < 0) { 2784d9585277SAl Viro if (create_error && error == -ENOENT) 2785d9585277SAl Viro error = create_error; 2786d18e9008SMiklos Szeredi goto out; 2787d18e9008SMiklos Szeredi } 2788d18e9008SMiklos Szeredi 2789d9585277SAl Viro if (error) { /* returned 1, that is */ 279030d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27912675a4ebSAl Viro error = -EIO; 2792d18e9008SMiklos Szeredi goto out; 2793d18e9008SMiklos Szeredi } 279430d90494SAl Viro if (file->f_path.dentry) { 2795d18e9008SMiklos Szeredi dput(dentry); 279630d90494SAl Viro dentry = file->f_path.dentry; 2797d18e9008SMiklos Szeredi } 279803da633aSAl Viro if (*opened & FILE_CREATED) 279903da633aSAl Viro fsnotify_create(dir, dentry); 280003da633aSAl Viro if (!dentry->d_inode) { 280103da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 280203da633aSAl Viro if (create_error) { 280362b2ce96SSage Weil error = create_error; 280462b2ce96SSage Weil goto out; 280562b2ce96SSage Weil } 280603da633aSAl Viro } else { 280703da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 280803da633aSAl Viro error = -EEXIST; 280903da633aSAl Viro goto out; 281003da633aSAl Viro } 281103da633aSAl Viro } 2812d18e9008SMiklos Szeredi goto looked_up; 2813d18e9008SMiklos Szeredi } 2814d18e9008SMiklos Szeredi 2815d18e9008SMiklos Szeredi /* 2816d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2817d18e9008SMiklos Szeredi * here. 2818d18e9008SMiklos Szeredi */ 281903da633aSAl Viro acc_mode = op->acc_mode; 282003da633aSAl Viro if (*opened & FILE_CREATED) { 282103da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 282203da633aSAl Viro fsnotify_create(dir, dentry); 282303da633aSAl Viro acc_mode = MAY_OPEN; 282403da633aSAl Viro } 28252675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28262675a4ebSAl Viro if (error) 28272675a4ebSAl Viro fput(file); 2828d18e9008SMiklos Szeredi 2829d18e9008SMiklos Szeredi out: 2830d18e9008SMiklos Szeredi dput(dentry); 28312675a4ebSAl Viro return error; 2832d18e9008SMiklos Szeredi 2833d18e9008SMiklos Szeredi no_open: 2834d18e9008SMiklos Szeredi if (need_lookup) { 283572bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2836d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28372675a4ebSAl Viro return PTR_ERR(dentry); 2838d18e9008SMiklos Szeredi 2839d18e9008SMiklos Szeredi if (create_error) { 2840d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2841d18e9008SMiklos Szeredi 28422675a4ebSAl Viro error = create_error; 2843d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2844d18e9008SMiklos Szeredi if (!dentry->d_inode) 2845d18e9008SMiklos Szeredi goto out; 2846d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2847d18e9008SMiklos Szeredi goto out; 2848d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2849e36cb0b8SDavid Howells d_is_reg(dentry)) { 2850d18e9008SMiklos Szeredi goto out; 2851d18e9008SMiklos Szeredi } 2852d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2853d18e9008SMiklos Szeredi } 2854d18e9008SMiklos Szeredi } 2855d18e9008SMiklos Szeredi looked_up: 2856d18e9008SMiklos Szeredi path->dentry = dentry; 2857d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28582675a4ebSAl Viro return 1; 2859d18e9008SMiklos Szeredi } 2860d18e9008SMiklos Szeredi 286131e6b01fSNick Piggin /* 28621acf0af9SDavid Howells * Look up and maybe create and open the last component. 2863d58ffd35SMiklos Szeredi * 2864d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2865d58ffd35SMiklos Szeredi * 28661acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28671acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28681acf0af9SDavid Howells * 28691acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28701acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28711acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28721acf0af9SDavid Howells * specified then a negative dentry may be returned. 28731acf0af9SDavid Howells * 28741acf0af9SDavid Howells * An error code is returned otherwise. 28751acf0af9SDavid Howells * 28761acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28771acf0af9SDavid Howells * cleared otherwise prior to returning. 2878d58ffd35SMiklos Szeredi */ 28792675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 288030d90494SAl Viro struct file *file, 2881d58ffd35SMiklos Szeredi const struct open_flags *op, 288264894cf8SAl Viro bool got_write, int *opened) 2883d58ffd35SMiklos Szeredi { 2884d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 288554ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2886d58ffd35SMiklos Szeredi struct dentry *dentry; 2887d58ffd35SMiklos Szeredi int error; 288854ef4872SMiklos Szeredi bool need_lookup; 2889d58ffd35SMiklos Szeredi 289047237687SAl Viro *opened &= ~FILE_CREATED; 2891201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2892d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28932675a4ebSAl Viro return PTR_ERR(dentry); 2894d58ffd35SMiklos Szeredi 2895d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2896d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2897d18e9008SMiklos Szeredi goto out_no_open; 2898d18e9008SMiklos Szeredi 2899d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 290064894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 290147237687SAl Viro need_lookup, opened); 2902d18e9008SMiklos Szeredi } 2903d18e9008SMiklos Szeredi 290454ef4872SMiklos Szeredi if (need_lookup) { 290554ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 290654ef4872SMiklos Szeredi 290772bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 290854ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29092675a4ebSAl Viro return PTR_ERR(dentry); 291054ef4872SMiklos Szeredi } 291154ef4872SMiklos Szeredi 2912d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2913d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2914d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2915d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2916d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2917d58ffd35SMiklos Szeredi /* 2918d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2919d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2920d58ffd35SMiklos Szeredi * the time when the file is created and when 2921d58ffd35SMiklos Szeredi * a permanent write count is taken through 2922015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2923d58ffd35SMiklos Szeredi */ 292464894cf8SAl Viro if (!got_write) { 292564894cf8SAl Viro error = -EROFS; 2926d58ffd35SMiklos Szeredi goto out_dput; 292764894cf8SAl Viro } 292847237687SAl Viro *opened |= FILE_CREATED; 2929d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2930d58ffd35SMiklos Szeredi if (error) 2931d58ffd35SMiklos Szeredi goto out_dput; 2932312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2933312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2934d58ffd35SMiklos Szeredi if (error) 2935d58ffd35SMiklos Szeredi goto out_dput; 2936d58ffd35SMiklos Szeredi } 2937d18e9008SMiklos Szeredi out_no_open: 2938d58ffd35SMiklos Szeredi path->dentry = dentry; 2939d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29402675a4ebSAl Viro return 1; 2941d58ffd35SMiklos Szeredi 2942d58ffd35SMiklos Szeredi out_dput: 2943d58ffd35SMiklos Szeredi dput(dentry); 29442675a4ebSAl Viro return error; 2945d58ffd35SMiklos Szeredi } 2946d58ffd35SMiklos Szeredi 2947d58ffd35SMiklos Szeredi /* 2948fe2d35ffSAl Viro * Handle the last step of open() 294931e6b01fSNick Piggin */ 2950896475d5SAl Viro static int do_last(struct nameidata *nd, 295130d90494SAl Viro struct file *file, const struct open_flags *op, 2952669abf4eSJeff Layton int *opened, struct filename *name) 2953fb1cc555SAl Viro { 2954a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2955ca344a89SAl Viro int open_flag = op->open_flag; 295677d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 295764894cf8SAl Viro bool got_write = false; 2958bcda7652SAl Viro int acc_mode = op->acc_mode; 2959254cf582SAl Viro unsigned seq; 2960a1eb3315SMiklos Szeredi struct inode *inode; 296116b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2962896475d5SAl Viro struct path path; 296316b1c1cdSMiklos Szeredi bool retried = false; 296416c2cd71SAl Viro int error; 2965fb1cc555SAl Viro 2966c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2967c3e380b0SAl Viro nd->flags |= op->intent; 2968c3e380b0SAl Viro 2969bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2970fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2971deb106c6SAl Viro if (unlikely(error)) 29722675a4ebSAl Viro return error; 2973e83db167SMiklos Szeredi goto finish_open; 29741f36f774SAl Viro } 2975a2c36b45SAl Viro 2976ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2977fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2978fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2979fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2980254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 298171574865SMiklos Szeredi if (likely(!error)) 298271574865SMiklos Szeredi goto finish_lookup; 298371574865SMiklos Szeredi 2984ce57dfc1SAl Viro if (error < 0) 2985deb106c6SAl Viro return error; 2986a1eb3315SMiklos Szeredi 298737d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2988b6183df7SMiklos Szeredi } else { 2989fe2d35ffSAl Viro /* create side of things */ 2990a3fbbde7SAl Viro /* 2991b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2992b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2993b6183df7SMiklos Szeredi * about to look up 2994a3fbbde7SAl Viro */ 29959f1fafeeSAl Viro error = complete_walk(nd); 2996e8bb73dfSAl Viro if (error) 29972675a4ebSAl Viro return error; 2998fe2d35ffSAl Viro 299933e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 30001f36f774SAl Viro /* trailing slashes? */ 3001deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3002deb106c6SAl Viro return -EISDIR; 3003b6183df7SMiklos Szeredi } 30041f36f774SAl Viro 300516b1c1cdSMiklos Szeredi retry_lookup: 300664894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 300764894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 300864894cf8SAl Viro if (!error) 300964894cf8SAl Viro got_write = true; 301064894cf8SAl Viro /* 301164894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 301264894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 301364894cf8SAl Viro * dropping this one anyway. 301464894cf8SAl Viro */ 301564894cf8SAl Viro } 3016a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3017896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3018fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3019fb1cc555SAl Viro 30202675a4ebSAl Viro if (error <= 0) { 30212675a4ebSAl Viro if (error) 3022d58ffd35SMiklos Szeredi goto out; 30236c0d46c4SAl Viro 302447237687SAl Viro if ((*opened & FILE_CREATED) || 3025496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 302677d660a8SMiklos Szeredi will_truncate = false; 3027d18e9008SMiklos Szeredi 3028adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3029d18e9008SMiklos Szeredi goto opened; 3030d18e9008SMiklos Szeredi } 3031d18e9008SMiklos Szeredi 303247237687SAl Viro if (*opened & FILE_CREATED) { 30339b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3034ca344a89SAl Viro open_flag &= ~O_TRUNC; 303577d660a8SMiklos Szeredi will_truncate = false; 3036bcda7652SAl Viro acc_mode = MAY_OPEN; 3037896475d5SAl Viro path_to_nameidata(&path, nd); 3038e83db167SMiklos Szeredi goto finish_open_created; 3039fb1cc555SAl Viro } 3040fb1cc555SAl Viro 3041fb1cc555SAl Viro /* 30423134f37eSJeff Layton * create/update audit record if it already exists. 3043fb1cc555SAl Viro */ 3044896475d5SAl Viro if (d_is_positive(path.dentry)) 3045896475d5SAl Viro audit_inode(name, path.dentry, 0); 3046fb1cc555SAl Viro 3047d18e9008SMiklos Szeredi /* 3048d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3049d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3050d18e9008SMiklos Szeredi * necessary...) 3051d18e9008SMiklos Szeredi */ 305264894cf8SAl Viro if (got_write) { 3053d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 305464894cf8SAl Viro got_write = false; 3055d18e9008SMiklos Szeredi } 3056d18e9008SMiklos Szeredi 3057deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3058deb106c6SAl Viro path_to_nameidata(&path, nd); 3059deb106c6SAl Viro return -EEXIST; 3060deb106c6SAl Viro } 3061fb1cc555SAl Viro 3062756daf26SNeilBrown error = follow_managed(&path, nd); 3063deb106c6SAl Viro if (unlikely(error < 0)) 3064deb106c6SAl Viro return error; 3065a3fbbde7SAl Viro 3066decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 306763afdfc7SDavid Howells inode = d_backing_inode(path.dentry); 3068254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3069deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3070896475d5SAl Viro path_to_nameidata(&path, nd); 3071deb106c6SAl Viro return -ENOENT; 307254c33e7fSMiklos Szeredi } 3073766c4cbfSAl Viro finish_lookup: 3074191d7f73SAl Viro if (nd->depth) 3075191d7f73SAl Viro put_link(nd); 3076181548c0SAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, 3077181548c0SAl Viro inode, seq); 3078deb106c6SAl Viro if (unlikely(error)) 3079d63ff28fSAl Viro return error; 3080fb1cc555SAl Viro 3081896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3082896475d5SAl Viro path_to_nameidata(&path, nd); 3083deb106c6SAl Viro return -ELOOP; 3084a5cfe2d5SAl Viro } 3085a5cfe2d5SAl Viro 3086896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3087896475d5SAl Viro path_to_nameidata(&path, nd); 308816b1c1cdSMiklos Szeredi } else { 308916b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3090896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3091896475d5SAl Viro nd->path.dentry = path.dentry; 309216b1c1cdSMiklos Szeredi 309316b1c1cdSMiklos Szeredi } 3094decf3400SMiklos Szeredi nd->inode = inode; 3095254cf582SAl Viro nd->seq = seq; 3096a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3097bc77daa7SAl Viro finish_open: 3098a3fbbde7SAl Viro error = complete_walk(nd); 309916b1c1cdSMiklos Szeredi if (error) { 310016b1c1cdSMiklos Szeredi path_put(&save_parent); 31012675a4ebSAl Viro return error; 310216b1c1cdSMiklos Szeredi } 3103bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3104fb1cc555SAl Viro error = -EISDIR; 310544b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31062675a4ebSAl Viro goto out; 3107af2f5542SMiklos Szeredi error = -ENOTDIR; 310844b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31092675a4ebSAl Viro goto out; 31104bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 311177d660a8SMiklos Szeredi will_truncate = false; 31126c0d46c4SAl Viro 31130f9d1a10SAl Viro if (will_truncate) { 31140f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31150f9d1a10SAl Viro if (error) 31162675a4ebSAl Viro goto out; 311764894cf8SAl Viro got_write = true; 31180f9d1a10SAl Viro } 3119e83db167SMiklos Szeredi finish_open_created: 3120bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3121ca344a89SAl Viro if (error) 31222675a4ebSAl Viro goto out; 31234aa7c634SMiklos Szeredi 31244aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31254aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31264aa7c634SMiklos Szeredi if (!error) { 31274aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31284aa7c634SMiklos Szeredi } else { 312930d90494SAl Viro if (error == -EOPENSTALE) 3130f60dc3dbSMiklos Szeredi goto stale_open; 3131015c3bbcSMiklos Szeredi goto out; 3132f60dc3dbSMiklos Szeredi } 3133a8277b9bSMiklos Szeredi opened: 31342675a4ebSAl Viro error = open_check_o_direct(file); 3135015c3bbcSMiklos Szeredi if (error) 3136015c3bbcSMiklos Szeredi goto exit_fput; 31373034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3138aa4caadbSMiklos Szeredi if (error) 3139aa4caadbSMiklos Szeredi goto exit_fput; 3140aa4caadbSMiklos Szeredi 31410f9d1a10SAl Viro if (will_truncate) { 31422675a4ebSAl Viro error = handle_truncate(file); 3143aa4caadbSMiklos Szeredi if (error) 3144aa4caadbSMiklos Szeredi goto exit_fput; 31450f9d1a10SAl Viro } 3146ca344a89SAl Viro out: 314764894cf8SAl Viro if (got_write) 31480f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 314916b1c1cdSMiklos Szeredi path_put(&save_parent); 31502675a4ebSAl Viro return error; 3151fb1cc555SAl Viro 3152015c3bbcSMiklos Szeredi exit_fput: 31532675a4ebSAl Viro fput(file); 31542675a4ebSAl Viro goto out; 3155015c3bbcSMiklos Szeredi 3156f60dc3dbSMiklos Szeredi stale_open: 3157f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3158f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3159f60dc3dbSMiklos Szeredi goto out; 3160f60dc3dbSMiklos Szeredi 3161f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3162f60dc3dbSMiklos Szeredi path_put(&nd->path); 3163f60dc3dbSMiklos Szeredi nd->path = save_parent; 3164f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3165f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3166f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 316764894cf8SAl Viro if (got_write) { 3168f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 316964894cf8SAl Viro got_write = false; 3170f60dc3dbSMiklos Szeredi } 3171f60dc3dbSMiklos Szeredi retried = true; 3172f60dc3dbSMiklos Szeredi goto retry_lookup; 3173fb1cc555SAl Viro } 3174fb1cc555SAl Viro 317560545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 317660545d0dSAl Viro struct nameidata *nd, int flags, 317760545d0dSAl Viro const struct open_flags *op, 317860545d0dSAl Viro struct file *file, int *opened) 317960545d0dSAl Viro { 318060545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 318160545d0dSAl Viro struct dentry *dentry, *child; 318260545d0dSAl Viro struct inode *dir; 31835eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 318460545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 318560545d0dSAl Viro if (unlikely(error)) 318660545d0dSAl Viro return error; 318760545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 318860545d0dSAl Viro if (unlikely(error)) 318960545d0dSAl Viro goto out; 319060545d0dSAl Viro /* we want directory to be writable */ 319160545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 319260545d0dSAl Viro if (error) 319360545d0dSAl Viro goto out2; 319460545d0dSAl Viro dentry = nd->path.dentry; 319560545d0dSAl Viro dir = dentry->d_inode; 319660545d0dSAl Viro if (!dir->i_op->tmpfile) { 319760545d0dSAl Viro error = -EOPNOTSUPP; 319860545d0dSAl Viro goto out2; 319960545d0dSAl Viro } 320060545d0dSAl Viro child = d_alloc(dentry, &name); 320160545d0dSAl Viro if (unlikely(!child)) { 320260545d0dSAl Viro error = -ENOMEM; 320360545d0dSAl Viro goto out2; 320460545d0dSAl Viro } 320560545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 320660545d0dSAl Viro nd->flags |= op->intent; 320760545d0dSAl Viro dput(nd->path.dentry); 320860545d0dSAl Viro nd->path.dentry = child; 320960545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 321060545d0dSAl Viro if (error) 321160545d0dSAl Viro goto out2; 321260545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 321369a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 321469a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 321560545d0dSAl Viro if (error) 321660545d0dSAl Viro goto out2; 321760545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 321860545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 321960545d0dSAl Viro if (error) 322060545d0dSAl Viro goto out2; 322160545d0dSAl Viro error = open_check_o_direct(file); 3222f4e0c30cSAl Viro if (error) { 322360545d0dSAl Viro fput(file); 3224f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3225f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3226f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3227f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3228f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3229f4e0c30cSAl Viro } 323060545d0dSAl Viro out2: 323160545d0dSAl Viro mnt_drop_write(nd->path.mnt); 323260545d0dSAl Viro out: 323360545d0dSAl Viro path_put(&nd->path); 323460545d0dSAl Viro return error; 323560545d0dSAl Viro } 323660545d0dSAl Viro 3237669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 323873d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32391da177e4SLinus Torvalds { 3240368ee9baSAl Viro const char *s; 324130d90494SAl Viro struct file *file; 324247237687SAl Viro int opened = 0; 324313aab428SAl Viro int error; 324431e6b01fSNick Piggin 324530d90494SAl Viro file = get_empty_filp(); 32461afc99beSAl Viro if (IS_ERR(file)) 32471afc99beSAl Viro return file; 324831e6b01fSNick Piggin 324930d90494SAl Viro file->f_flags = op->open_flag; 325031e6b01fSNick Piggin 3251bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 325260545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3253f15133dfSAl Viro goto out2; 325460545d0dSAl Viro } 325560545d0dSAl Viro 3256368ee9baSAl Viro s = path_init(dfd, pathname, flags, nd); 3257368ee9baSAl Viro if (IS_ERR(s)) { 3258368ee9baSAl Viro put_filp(file); 3259368ee9baSAl Viro return ERR_CAST(s); 3260368ee9baSAl Viro } 32613bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 32623bdba28bSAl Viro (error = do_last(nd, file, op, &opened, pathname)) > 0) { 326373d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32643bdba28bSAl Viro s = trailing_symlink(nd); 32653bdba28bSAl Viro if (IS_ERR(s)) { 32663bdba28bSAl Viro error = PTR_ERR(s); 32672675a4ebSAl Viro break; 3268806b681cSAl Viro } 32693bdba28bSAl Viro } 3270deb106c6SAl Viro terminate_walk(nd); 3271893b7775SAl Viro path_cleanup(nd); 3272f15133dfSAl Viro out2: 32732675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32742675a4ebSAl Viro BUG_ON(!error); 327530d90494SAl Viro put_filp(file); 3276015c3bbcSMiklos Szeredi } 32772675a4ebSAl Viro if (unlikely(error)) { 32782675a4ebSAl Viro if (error == -EOPENSTALE) { 32792675a4ebSAl Viro if (flags & LOOKUP_RCU) 32802675a4ebSAl Viro error = -ECHILD; 32812675a4ebSAl Viro else 32822675a4ebSAl Viro error = -ESTALE; 32832675a4ebSAl Viro } 32842675a4ebSAl Viro file = ERR_PTR(error); 32852675a4ebSAl Viro } 32862675a4ebSAl Viro return file; 3287de459215SKirill Korotaev } 32881da177e4SLinus Torvalds 3289669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3290f9652e10SAl Viro const struct open_flags *op) 329113aab428SAl Viro { 3292756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3293f9652e10SAl Viro int flags = op->lookup_flags; 329413aab428SAl Viro struct file *filp; 329513aab428SAl Viro 329673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 329713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 329873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 329913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 330073d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3301756daf26SNeilBrown restore_nameidata(saved_nd); 330213aab428SAl Viro return filp; 330313aab428SAl Viro } 330413aab428SAl Viro 330573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3306f9652e10SAl Viro const char *name, const struct open_flags *op) 330773d049a4SAl Viro { 3308756daf26SNeilBrown struct nameidata nd, *saved_nd; 330973d049a4SAl Viro struct file *file; 331051689104SPaul Moore struct filename *filename; 3311f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 331273d049a4SAl Viro 331373d049a4SAl Viro nd.root.mnt = mnt; 331473d049a4SAl Viro nd.root.dentry = dentry; 331573d049a4SAl Viro 3316b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 331773d049a4SAl Viro return ERR_PTR(-ELOOP); 331873d049a4SAl Viro 331951689104SPaul Moore filename = getname_kernel(name); 332051689104SPaul Moore if (unlikely(IS_ERR(filename))) 332151689104SPaul Moore return ERR_CAST(filename); 332251689104SPaul Moore 3323756daf26SNeilBrown saved_nd = set_nameidata(&nd); 332451689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 332573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 332651689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 332773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 332851689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3329756daf26SNeilBrown restore_nameidata(saved_nd); 333051689104SPaul Moore putname(filename); 333173d049a4SAl Viro return file; 333273d049a4SAl Viro } 333373d049a4SAl Viro 3334fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33351ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33361da177e4SLinus Torvalds { 3337c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3338ed75e95dSAl Viro struct nameidata nd; 3339c30dabfeSJan Kara int err2; 33401ac12b4bSJeff Layton int error; 33411ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33421ac12b4bSJeff Layton 33431ac12b4bSJeff Layton /* 33441ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33451ac12b4bSJeff Layton * other flags passed in are ignored! 33461ac12b4bSJeff Layton */ 33471ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33481ac12b4bSJeff Layton 33498bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3350ed75e95dSAl Viro if (error) 3351ed75e95dSAl Viro return ERR_PTR(error); 33521da177e4SLinus Torvalds 3353c663e5d8SChristoph Hellwig /* 3354c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3355c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3356c663e5d8SChristoph Hellwig */ 3357ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3358ed75e95dSAl Viro goto out; 3359ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3360ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3361c663e5d8SChristoph Hellwig 3362c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3363c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3364c663e5d8SChristoph Hellwig /* 3365c663e5d8SChristoph Hellwig * Do the final lookup. 3366c663e5d8SChristoph Hellwig */ 3367ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33686a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33691da177e4SLinus Torvalds if (IS_ERR(dentry)) 3370a8104a9fSAl Viro goto unlock; 3371c663e5d8SChristoph Hellwig 3372a8104a9fSAl Viro error = -EEXIST; 3373b18825a7SDavid Howells if (d_is_positive(dentry)) 3374a8104a9fSAl Viro goto fail; 3375b18825a7SDavid Howells 3376c663e5d8SChristoph Hellwig /* 3377c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3378c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3379c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3380c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3381c663e5d8SChristoph Hellwig */ 3382ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3383a8104a9fSAl Viro error = -ENOENT; 3384ed75e95dSAl Viro goto fail; 3385e9baf6e5SAl Viro } 3386c30dabfeSJan Kara if (unlikely(err2)) { 3387c30dabfeSJan Kara error = err2; 3388a8104a9fSAl Viro goto fail; 3389c30dabfeSJan Kara } 3390ed75e95dSAl Viro *path = nd.path; 3391e9baf6e5SAl Viro return dentry; 33921da177e4SLinus Torvalds fail: 3393a8104a9fSAl Viro dput(dentry); 3394a8104a9fSAl Viro dentry = ERR_PTR(error); 3395a8104a9fSAl Viro unlock: 3396dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3397c30dabfeSJan Kara if (!err2) 3398c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3399ed75e95dSAl Viro out: 3400dae6ad8fSAl Viro path_put(&nd.path); 3401ed75e95dSAl Viro return dentry; 3402dae6ad8fSAl Viro } 3403fa14a0b8SAl Viro 3404fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3405fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3406fa14a0b8SAl Viro { 340751689104SPaul Moore struct filename *filename = getname_kernel(pathname); 340851689104SPaul Moore struct dentry *res; 340951689104SPaul Moore 341051689104SPaul Moore if (IS_ERR(filename)) 341151689104SPaul Moore return ERR_CAST(filename); 341251689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 341351689104SPaul Moore putname(filename); 341451689104SPaul Moore return res; 3415fa14a0b8SAl Viro } 3416dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3417dae6ad8fSAl Viro 3418921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3419921a1650SAl Viro { 3420921a1650SAl Viro dput(dentry); 3421921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3422a8104a9fSAl Viro mnt_drop_write(path->mnt); 3423921a1650SAl Viro path_put(path); 3424921a1650SAl Viro } 3425921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3426921a1650SAl Viro 34271ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34281ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3429dae6ad8fSAl Viro { 343091a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3431dae6ad8fSAl Viro struct dentry *res; 3432dae6ad8fSAl Viro if (IS_ERR(tmp)) 3433dae6ad8fSAl Viro return ERR_CAST(tmp); 3434fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3435dae6ad8fSAl Viro putname(tmp); 3436dae6ad8fSAl Viro return res; 3437dae6ad8fSAl Viro } 3438dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3439dae6ad8fSAl Viro 34401a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34411da177e4SLinus Torvalds { 3442a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34431da177e4SLinus Torvalds 34441da177e4SLinus Torvalds if (error) 34451da177e4SLinus Torvalds return error; 34461da177e4SLinus Torvalds 3447975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34481da177e4SLinus Torvalds return -EPERM; 34491da177e4SLinus Torvalds 3450acfa4380SAl Viro if (!dir->i_op->mknod) 34511da177e4SLinus Torvalds return -EPERM; 34521da177e4SLinus Torvalds 345308ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 345408ce5f16SSerge E. Hallyn if (error) 345508ce5f16SSerge E. Hallyn return error; 345608ce5f16SSerge E. Hallyn 34571da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34581da177e4SLinus Torvalds if (error) 34591da177e4SLinus Torvalds return error; 34601da177e4SLinus Torvalds 34611da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3462a74574aaSStephen Smalley if (!error) 3463f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34641da177e4SLinus Torvalds return error; 34651da177e4SLinus Torvalds } 34664d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34671da177e4SLinus Torvalds 3468f69aac00SAl Viro static int may_mknod(umode_t mode) 3469463c3197SDave Hansen { 3470463c3197SDave Hansen switch (mode & S_IFMT) { 3471463c3197SDave Hansen case S_IFREG: 3472463c3197SDave Hansen case S_IFCHR: 3473463c3197SDave Hansen case S_IFBLK: 3474463c3197SDave Hansen case S_IFIFO: 3475463c3197SDave Hansen case S_IFSOCK: 3476463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3477463c3197SDave Hansen return 0; 3478463c3197SDave Hansen case S_IFDIR: 3479463c3197SDave Hansen return -EPERM; 3480463c3197SDave Hansen default: 3481463c3197SDave Hansen return -EINVAL; 3482463c3197SDave Hansen } 3483463c3197SDave Hansen } 3484463c3197SDave Hansen 34858208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34862e4d0924SHeiko Carstens unsigned, dev) 34871da177e4SLinus Torvalds { 34881da177e4SLinus Torvalds struct dentry *dentry; 3489dae6ad8fSAl Viro struct path path; 3490dae6ad8fSAl Viro int error; 3491972567f1SJeff Layton unsigned int lookup_flags = 0; 34921da177e4SLinus Torvalds 34938e4bfca1SAl Viro error = may_mknod(mode); 34948e4bfca1SAl Viro if (error) 34958e4bfca1SAl Viro return error; 3496972567f1SJeff Layton retry: 3497972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3498dae6ad8fSAl Viro if (IS_ERR(dentry)) 3499dae6ad8fSAl Viro return PTR_ERR(dentry); 35002ad94ae6SAl Viro 3501dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3502ce3b0f8dSAl Viro mode &= ~current_umask(); 3503dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3504be6d3e56SKentaro Takeda if (error) 3505a8104a9fSAl Viro goto out; 35061da177e4SLinus Torvalds switch (mode & S_IFMT) { 35071da177e4SLinus Torvalds case 0: case S_IFREG: 3508312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35091da177e4SLinus Torvalds break; 35101da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3511dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35121da177e4SLinus Torvalds new_decode_dev(dev)); 35131da177e4SLinus Torvalds break; 35141da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3515dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35161da177e4SLinus Torvalds break; 35171da177e4SLinus Torvalds } 3518a8104a9fSAl Viro out: 3519921a1650SAl Viro done_path_create(&path, dentry); 3520972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3521972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3522972567f1SJeff Layton goto retry; 3523972567f1SJeff Layton } 35241da177e4SLinus Torvalds return error; 35251da177e4SLinus Torvalds } 35261da177e4SLinus Torvalds 35278208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35285590ff0dSUlrich Drepper { 35295590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35305590ff0dSUlrich Drepper } 35315590ff0dSUlrich Drepper 353218bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35331da177e4SLinus Torvalds { 3534a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35358de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35361da177e4SLinus Torvalds 35371da177e4SLinus Torvalds if (error) 35381da177e4SLinus Torvalds return error; 35391da177e4SLinus Torvalds 3540acfa4380SAl Viro if (!dir->i_op->mkdir) 35411da177e4SLinus Torvalds return -EPERM; 35421da177e4SLinus Torvalds 35431da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35441da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35451da177e4SLinus Torvalds if (error) 35461da177e4SLinus Torvalds return error; 35471da177e4SLinus Torvalds 35488de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35498de52778SAl Viro return -EMLINK; 35508de52778SAl Viro 35511da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3552a74574aaSStephen Smalley if (!error) 3553f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35541da177e4SLinus Torvalds return error; 35551da177e4SLinus Torvalds } 35564d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35571da177e4SLinus Torvalds 3558a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35591da177e4SLinus Torvalds { 35606902d925SDave Hansen struct dentry *dentry; 3561dae6ad8fSAl Viro struct path path; 3562dae6ad8fSAl Viro int error; 3563b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35641da177e4SLinus Torvalds 3565b76d8b82SJeff Layton retry: 3566b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35676902d925SDave Hansen if (IS_ERR(dentry)) 3568dae6ad8fSAl Viro return PTR_ERR(dentry); 35696902d925SDave Hansen 3570dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3571ce3b0f8dSAl Viro mode &= ~current_umask(); 3572dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3573a8104a9fSAl Viro if (!error) 3574dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3575921a1650SAl Viro done_path_create(&path, dentry); 3576b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3577b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3578b76d8b82SJeff Layton goto retry; 3579b76d8b82SJeff Layton } 35801da177e4SLinus Torvalds return error; 35811da177e4SLinus Torvalds } 35821da177e4SLinus Torvalds 3583a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35845590ff0dSUlrich Drepper { 35855590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35865590ff0dSUlrich Drepper } 35875590ff0dSUlrich Drepper 35881da177e4SLinus Torvalds /* 3589a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3590c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3591a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3592a71905f0SSage Weil * then we drop the dentry now. 35931da177e4SLinus Torvalds * 35941da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35951da177e4SLinus Torvalds * do a 35961da177e4SLinus Torvalds * 35971da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35981da177e4SLinus Torvalds * return -EBUSY; 35991da177e4SLinus Torvalds * 36001da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36011da177e4SLinus Torvalds * that is still in use by something else.. 36021da177e4SLinus Torvalds */ 36031da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36041da177e4SLinus Torvalds { 36051da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36061da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 360798474236SWaiman Long if (dentry->d_lockref.count == 1) 36081da177e4SLinus Torvalds __d_drop(dentry); 36091da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36101da177e4SLinus Torvalds } 36114d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36121da177e4SLinus Torvalds 36131da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36141da177e4SLinus Torvalds { 36151da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36161da177e4SLinus Torvalds 36171da177e4SLinus Torvalds if (error) 36181da177e4SLinus Torvalds return error; 36191da177e4SLinus Torvalds 3620acfa4380SAl Viro if (!dir->i_op->rmdir) 36211da177e4SLinus Torvalds return -EPERM; 36221da177e4SLinus Torvalds 36231d2ef590SAl Viro dget(dentry); 36241b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3625912dbc15SSage Weil 36261da177e4SLinus Torvalds error = -EBUSY; 36277af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3628912dbc15SSage Weil goto out; 3629912dbc15SSage Weil 36301da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3631912dbc15SSage Weil if (error) 3632912dbc15SSage Weil goto out; 3633912dbc15SSage Weil 36343cebde24SSage Weil shrink_dcache_parent(dentry); 36351da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3636912dbc15SSage Weil if (error) 3637912dbc15SSage Weil goto out; 3638912dbc15SSage Weil 36391da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3640d83c49f3SAl Viro dont_mount(dentry); 36418ed936b5SEric W. Biederman detach_mounts(dentry); 36421da177e4SLinus Torvalds 3643912dbc15SSage Weil out: 3644912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36451d2ef590SAl Viro dput(dentry); 3646912dbc15SSage Weil if (!error) 3647912dbc15SSage Weil d_delete(dentry); 36481da177e4SLinus Torvalds return error; 36491da177e4SLinus Torvalds } 36504d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36511da177e4SLinus Torvalds 36525590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36531da177e4SLinus Torvalds { 36541da177e4SLinus Torvalds int error = 0; 365591a27b2aSJeff Layton struct filename *name; 36561da177e4SLinus Torvalds struct dentry *dentry; 3657f5beed75SAl Viro struct path path; 3658f5beed75SAl Viro struct qstr last; 3659f5beed75SAl Viro int type; 3660c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3661c6ee9206SJeff Layton retry: 3662f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3663f5beed75SAl Viro &path, &last, &type, lookup_flags); 366491a27b2aSJeff Layton if (IS_ERR(name)) 366591a27b2aSJeff Layton return PTR_ERR(name); 36661da177e4SLinus Torvalds 3667f5beed75SAl Viro switch (type) { 36681da177e4SLinus Torvalds case LAST_DOTDOT: 36691da177e4SLinus Torvalds error = -ENOTEMPTY; 36701da177e4SLinus Torvalds goto exit1; 36711da177e4SLinus Torvalds case LAST_DOT: 36721da177e4SLinus Torvalds error = -EINVAL; 36731da177e4SLinus Torvalds goto exit1; 36741da177e4SLinus Torvalds case LAST_ROOT: 36751da177e4SLinus Torvalds error = -EBUSY; 36761da177e4SLinus Torvalds goto exit1; 36771da177e4SLinus Torvalds } 36780612d9fbSOGAWA Hirofumi 3679f5beed75SAl Viro error = mnt_want_write(path.mnt); 3680c30dabfeSJan Kara if (error) 3681c30dabfeSJan Kara goto exit1; 36820612d9fbSOGAWA Hirofumi 3683f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3684f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 36851da177e4SLinus Torvalds error = PTR_ERR(dentry); 36866902d925SDave Hansen if (IS_ERR(dentry)) 36876902d925SDave Hansen goto exit2; 3688e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3689e6bc45d6STheodore Ts'o error = -ENOENT; 3690e6bc45d6STheodore Ts'o goto exit3; 3691e6bc45d6STheodore Ts'o } 3692f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3693be6d3e56SKentaro Takeda if (error) 3694c30dabfeSJan Kara goto exit3; 3695f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 36960622753bSDave Hansen exit3: 36971da177e4SLinus Torvalds dput(dentry); 36986902d925SDave Hansen exit2: 3699f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3700f5beed75SAl Viro mnt_drop_write(path.mnt); 37011da177e4SLinus Torvalds exit1: 3702f5beed75SAl Viro path_put(&path); 37031da177e4SLinus Torvalds putname(name); 3704c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3705c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3706c6ee9206SJeff Layton goto retry; 3707c6ee9206SJeff Layton } 37081da177e4SLinus Torvalds return error; 37091da177e4SLinus Torvalds } 37101da177e4SLinus Torvalds 37113cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37125590ff0dSUlrich Drepper { 37135590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37145590ff0dSUlrich Drepper } 37155590ff0dSUlrich Drepper 3716b21996e3SJ. Bruce Fields /** 3717b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3718b21996e3SJ. Bruce Fields * @dir: parent directory 3719b21996e3SJ. Bruce Fields * @dentry: victim 3720b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3721b21996e3SJ. Bruce Fields * 3722b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3723b21996e3SJ. Bruce Fields * 3724b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3725b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3726b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3727b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3728b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3729b21996e3SJ. Bruce Fields * 3730b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3731b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3732b21996e3SJ. Bruce Fields * to be NFS exported. 3733b21996e3SJ. Bruce Fields */ 3734b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37351da177e4SLinus Torvalds { 37369accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37371da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37381da177e4SLinus Torvalds 37391da177e4SLinus Torvalds if (error) 37401da177e4SLinus Torvalds return error; 37411da177e4SLinus Torvalds 3742acfa4380SAl Viro if (!dir->i_op->unlink) 37431da177e4SLinus Torvalds return -EPERM; 37441da177e4SLinus Torvalds 37459accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37468ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37471da177e4SLinus Torvalds error = -EBUSY; 37481da177e4SLinus Torvalds else { 37491da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3750bec1052eSAl Viro if (!error) { 37515a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37525a14696cSJ. Bruce Fields if (error) 3753b21996e3SJ. Bruce Fields goto out; 37541da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37558ed936b5SEric W. Biederman if (!error) { 3756d83c49f3SAl Viro dont_mount(dentry); 37578ed936b5SEric W. Biederman detach_mounts(dentry); 37588ed936b5SEric W. Biederman } 3759bec1052eSAl Viro } 37601da177e4SLinus Torvalds } 3761b21996e3SJ. Bruce Fields out: 37629accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37631da177e4SLinus Torvalds 37641da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37651da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37669accbb97SJ. Bruce Fields fsnotify_link_count(target); 37671da177e4SLinus Torvalds d_delete(dentry); 37681da177e4SLinus Torvalds } 37690eeca283SRobert Love 37701da177e4SLinus Torvalds return error; 37711da177e4SLinus Torvalds } 37724d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37731da177e4SLinus Torvalds 37741da177e4SLinus Torvalds /* 37751da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37761b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37771da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37781da177e4SLinus Torvalds * while waiting on the I/O. 37791da177e4SLinus Torvalds */ 37805590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37811da177e4SLinus Torvalds { 37822ad94ae6SAl Viro int error; 378391a27b2aSJeff Layton struct filename *name; 37841da177e4SLinus Torvalds struct dentry *dentry; 3785f5beed75SAl Viro struct path path; 3786f5beed75SAl Viro struct qstr last; 3787f5beed75SAl Viro int type; 37881da177e4SLinus Torvalds struct inode *inode = NULL; 3789b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37905d18f813SJeff Layton unsigned int lookup_flags = 0; 37915d18f813SJeff Layton retry: 3792f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3793f5beed75SAl Viro &path, &last, &type, lookup_flags); 379491a27b2aSJeff Layton if (IS_ERR(name)) 379591a27b2aSJeff Layton return PTR_ERR(name); 37962ad94ae6SAl Viro 37971da177e4SLinus Torvalds error = -EISDIR; 3798f5beed75SAl Viro if (type != LAST_NORM) 37991da177e4SLinus Torvalds goto exit1; 38000612d9fbSOGAWA Hirofumi 3801f5beed75SAl Viro error = mnt_want_write(path.mnt); 3802c30dabfeSJan Kara if (error) 3803c30dabfeSJan Kara goto exit1; 3804b21996e3SJ. Bruce Fields retry_deleg: 3805f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3806f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38071da177e4SLinus Torvalds error = PTR_ERR(dentry); 38081da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38091da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3810f5beed75SAl Viro if (last.name[last.len]) 381150338b88STörök Edwin goto slashes; 38121da177e4SLinus Torvalds inode = dentry->d_inode; 3813b18825a7SDavid Howells if (d_is_negative(dentry)) 3814e6bc45d6STheodore Ts'o goto slashes; 38157de9c6eeSAl Viro ihold(inode); 3816f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3817be6d3e56SKentaro Takeda if (error) 3818c30dabfeSJan Kara goto exit2; 3819f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38201da177e4SLinus Torvalds exit2: 38211da177e4SLinus Torvalds dput(dentry); 38221da177e4SLinus Torvalds } 3823f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38241da177e4SLinus Torvalds if (inode) 38251da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3826b21996e3SJ. Bruce Fields inode = NULL; 3827b21996e3SJ. Bruce Fields if (delegated_inode) { 38285a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3829b21996e3SJ. Bruce Fields if (!error) 3830b21996e3SJ. Bruce Fields goto retry_deleg; 3831b21996e3SJ. Bruce Fields } 3832f5beed75SAl Viro mnt_drop_write(path.mnt); 38331da177e4SLinus Torvalds exit1: 3834f5beed75SAl Viro path_put(&path); 38351da177e4SLinus Torvalds putname(name); 38365d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38375d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38385d18f813SJeff Layton inode = NULL; 38395d18f813SJeff Layton goto retry; 38405d18f813SJeff Layton } 38411da177e4SLinus Torvalds return error; 38421da177e4SLinus Torvalds 38431da177e4SLinus Torvalds slashes: 3844b18825a7SDavid Howells if (d_is_negative(dentry)) 3845b18825a7SDavid Howells error = -ENOENT; 384644b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3847b18825a7SDavid Howells error = -EISDIR; 3848b18825a7SDavid Howells else 3849b18825a7SDavid Howells error = -ENOTDIR; 38501da177e4SLinus Torvalds goto exit2; 38511da177e4SLinus Torvalds } 38521da177e4SLinus Torvalds 38532e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38545590ff0dSUlrich Drepper { 38555590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38565590ff0dSUlrich Drepper return -EINVAL; 38575590ff0dSUlrich Drepper 38585590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38595590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38605590ff0dSUlrich Drepper 38615590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38625590ff0dSUlrich Drepper } 38635590ff0dSUlrich Drepper 38643480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38655590ff0dSUlrich Drepper { 38665590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38675590ff0dSUlrich Drepper } 38685590ff0dSUlrich Drepper 3869db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38701da177e4SLinus Torvalds { 3871a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38721da177e4SLinus Torvalds 38731da177e4SLinus Torvalds if (error) 38741da177e4SLinus Torvalds return error; 38751da177e4SLinus Torvalds 3876acfa4380SAl Viro if (!dir->i_op->symlink) 38771da177e4SLinus Torvalds return -EPERM; 38781da177e4SLinus Torvalds 38791da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38801da177e4SLinus Torvalds if (error) 38811da177e4SLinus Torvalds return error; 38821da177e4SLinus Torvalds 38831da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3884a74574aaSStephen Smalley if (!error) 3885f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38861da177e4SLinus Torvalds return error; 38871da177e4SLinus Torvalds } 38884d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38891da177e4SLinus Torvalds 38902e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38912e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38921da177e4SLinus Torvalds { 38932ad94ae6SAl Viro int error; 389491a27b2aSJeff Layton struct filename *from; 38956902d925SDave Hansen struct dentry *dentry; 3896dae6ad8fSAl Viro struct path path; 3897f46d3567SJeff Layton unsigned int lookup_flags = 0; 38981da177e4SLinus Torvalds 38991da177e4SLinus Torvalds from = getname(oldname); 39001da177e4SLinus Torvalds if (IS_ERR(from)) 39011da177e4SLinus Torvalds return PTR_ERR(from); 3902f46d3567SJeff Layton retry: 3903f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39041da177e4SLinus Torvalds error = PTR_ERR(dentry); 39056902d925SDave Hansen if (IS_ERR(dentry)) 3906dae6ad8fSAl Viro goto out_putname; 39076902d925SDave Hansen 390891a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3909a8104a9fSAl Viro if (!error) 391091a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3911921a1650SAl Viro done_path_create(&path, dentry); 3912f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3913f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3914f46d3567SJeff Layton goto retry; 3915f46d3567SJeff Layton } 39166902d925SDave Hansen out_putname: 39171da177e4SLinus Torvalds putname(from); 39181da177e4SLinus Torvalds return error; 39191da177e4SLinus Torvalds } 39201da177e4SLinus Torvalds 39213480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39225590ff0dSUlrich Drepper { 39235590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39245590ff0dSUlrich Drepper } 39255590ff0dSUlrich Drepper 3926146a8595SJ. Bruce Fields /** 3927146a8595SJ. Bruce Fields * vfs_link - create a new link 3928146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3929146a8595SJ. Bruce Fields * @dir: new parent 3930146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3931146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3932146a8595SJ. Bruce Fields * 3933146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3934146a8595SJ. Bruce Fields * 3935146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3936146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3937146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3938146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3939146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3940146a8595SJ. Bruce Fields * 3941146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3942146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3943146a8595SJ. Bruce Fields * to be NFS exported. 3944146a8595SJ. Bruce Fields */ 3945146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39461da177e4SLinus Torvalds { 39471da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39488de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39491da177e4SLinus Torvalds int error; 39501da177e4SLinus Torvalds 39511da177e4SLinus Torvalds if (!inode) 39521da177e4SLinus Torvalds return -ENOENT; 39531da177e4SLinus Torvalds 3954a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39551da177e4SLinus Torvalds if (error) 39561da177e4SLinus Torvalds return error; 39571da177e4SLinus Torvalds 39581da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39591da177e4SLinus Torvalds return -EXDEV; 39601da177e4SLinus Torvalds 39611da177e4SLinus Torvalds /* 39621da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39631da177e4SLinus Torvalds */ 39641da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39651da177e4SLinus Torvalds return -EPERM; 3966acfa4380SAl Viro if (!dir->i_op->link) 39671da177e4SLinus Torvalds return -EPERM; 39687e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39691da177e4SLinus Torvalds return -EPERM; 39701da177e4SLinus Torvalds 39711da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39721da177e4SLinus Torvalds if (error) 39731da177e4SLinus Torvalds return error; 39741da177e4SLinus Torvalds 39757e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3976aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3977f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3978aae8a97dSAneesh Kumar K.V error = -ENOENT; 39798de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39808de52778SAl Viro error = -EMLINK; 3981146a8595SJ. Bruce Fields else { 3982146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3983146a8595SJ. Bruce Fields if (!error) 39841da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3985146a8595SJ. Bruce Fields } 3986f4e0c30cSAl Viro 3987f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3988f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3989f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3990f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3991f4e0c30cSAl Viro } 39927e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3993e31e14ecSStephen Smalley if (!error) 39947e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39951da177e4SLinus Torvalds return error; 39961da177e4SLinus Torvalds } 39974d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39981da177e4SLinus Torvalds 39991da177e4SLinus Torvalds /* 40001da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40011da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40021da177e4SLinus Torvalds * newname. --KAB 40031da177e4SLinus Torvalds * 40041da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40051da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40061da177e4SLinus Torvalds * and other special files. --ADM 40071da177e4SLinus Torvalds */ 40082e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40092e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40101da177e4SLinus Torvalds { 40111da177e4SLinus Torvalds struct dentry *new_dentry; 4012dae6ad8fSAl Viro struct path old_path, new_path; 4013146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 401411a7b371SAneesh Kumar K.V int how = 0; 40151da177e4SLinus Torvalds int error; 40161da177e4SLinus Torvalds 401711a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4018c04030e1SUlrich Drepper return -EINVAL; 401911a7b371SAneesh Kumar K.V /* 4020f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4021f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4022f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 402311a7b371SAneesh Kumar K.V */ 4024f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4025f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4026f0cc6ffbSLinus Torvalds return -ENOENT; 402711a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4028f0cc6ffbSLinus Torvalds } 4029c04030e1SUlrich Drepper 403011a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 403111a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4032442e31caSJeff Layton retry: 403311a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40341da177e4SLinus Torvalds if (error) 40352ad94ae6SAl Viro return error; 40362ad94ae6SAl Viro 4037442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4038442e31caSJeff Layton (how & LOOKUP_REVAL)); 40391da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40406902d925SDave Hansen if (IS_ERR(new_dentry)) 4041dae6ad8fSAl Viro goto out; 4042dae6ad8fSAl Viro 4043dae6ad8fSAl Viro error = -EXDEV; 4044dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4045dae6ad8fSAl Viro goto out_dput; 4046800179c9SKees Cook error = may_linkat(&old_path); 4047800179c9SKees Cook if (unlikely(error)) 4048800179c9SKees Cook goto out_dput; 4049dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4050be6d3e56SKentaro Takeda if (error) 4051a8104a9fSAl Viro goto out_dput; 4052146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 405375c3f29dSDave Hansen out_dput: 4054921a1650SAl Viro done_path_create(&new_path, new_dentry); 4055146a8595SJ. Bruce Fields if (delegated_inode) { 4056146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4057d22e6338SOleg Drokin if (!error) { 4058d22e6338SOleg Drokin path_put(&old_path); 4059146a8595SJ. Bruce Fields goto retry; 4060146a8595SJ. Bruce Fields } 4061d22e6338SOleg Drokin } 4062442e31caSJeff Layton if (retry_estale(error, how)) { 4063d22e6338SOleg Drokin path_put(&old_path); 4064442e31caSJeff Layton how |= LOOKUP_REVAL; 4065442e31caSJeff Layton goto retry; 4066442e31caSJeff Layton } 40671da177e4SLinus Torvalds out: 40682d8f3038SAl Viro path_put(&old_path); 40691da177e4SLinus Torvalds 40701da177e4SLinus Torvalds return error; 40711da177e4SLinus Torvalds } 40721da177e4SLinus Torvalds 40733480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40745590ff0dSUlrich Drepper { 4075c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40765590ff0dSUlrich Drepper } 40775590ff0dSUlrich Drepper 4078bc27027aSMiklos Szeredi /** 4079bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4080bc27027aSMiklos Szeredi * @old_dir: parent of source 4081bc27027aSMiklos Szeredi * @old_dentry: source 4082bc27027aSMiklos Szeredi * @new_dir: parent of destination 4083bc27027aSMiklos Szeredi * @new_dentry: destination 4084bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4085520c8b16SMiklos Szeredi * @flags: rename flags 4086bc27027aSMiklos Szeredi * 4087bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4088bc27027aSMiklos Szeredi * 4089bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4090bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4091bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4092bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4093bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4094bc27027aSMiklos Szeredi * so. 4095bc27027aSMiklos Szeredi * 4096bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4097bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4098bc27027aSMiklos Szeredi * to be NFS exported. 4099bc27027aSMiklos Szeredi * 41001da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41011da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41021da177e4SLinus Torvalds * Problems: 4103d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41041da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41051da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4106a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41071da177e4SLinus Torvalds * story. 41086cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41096cedba89SJ. Bruce Fields * and source (if it is not a directory). 41101b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41111da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41121da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4113a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41141da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41151da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41161da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4117a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41181da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41191da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41201da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4121e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41221b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41231da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4124c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41251da177e4SLinus Torvalds * locking]. 41261da177e4SLinus Torvalds */ 41271da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41288e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4129520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41301da177e4SLinus Torvalds { 41311da177e4SLinus Torvalds int error; 4132bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 413359b0df21SEric Paris const unsigned char *old_name; 4134bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4135bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4136da1ce067SMiklos Szeredi bool new_is_dir = false; 4137da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41381da177e4SLinus Torvalds 4139bc27027aSMiklos Szeredi if (source == target) 41401da177e4SLinus Torvalds return 0; 41411da177e4SLinus Torvalds 41421da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41431da177e4SLinus Torvalds if (error) 41441da177e4SLinus Torvalds return error; 41451da177e4SLinus Torvalds 4146da1ce067SMiklos Szeredi if (!target) { 4147a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4148da1ce067SMiklos Szeredi } else { 4149da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4150da1ce067SMiklos Szeredi 4151da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41521da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4153da1ce067SMiklos Szeredi else 4154da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4155da1ce067SMiklos Szeredi } 41561da177e4SLinus Torvalds if (error) 41571da177e4SLinus Torvalds return error; 41581da177e4SLinus Torvalds 41597177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41601da177e4SLinus Torvalds return -EPERM; 41611da177e4SLinus Torvalds 4162520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4163520c8b16SMiklos Szeredi return -EINVAL; 4164520c8b16SMiklos Szeredi 4165bc27027aSMiklos Szeredi /* 4166bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4167bc27027aSMiklos Szeredi * we'll need to flip '..'. 4168bc27027aSMiklos Szeredi */ 4169da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4170da1ce067SMiklos Szeredi if (is_dir) { 4171bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4172bc27027aSMiklos Szeredi if (error) 4173bc27027aSMiklos Szeredi return error; 4174bc27027aSMiklos Szeredi } 4175da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4176da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4177da1ce067SMiklos Szeredi if (error) 4178da1ce067SMiklos Szeredi return error; 4179da1ce067SMiklos Szeredi } 4180da1ce067SMiklos Szeredi } 41810eeca283SRobert Love 41820b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41830b3974ebSMiklos Szeredi flags); 4184bc27027aSMiklos Szeredi if (error) 4185bc27027aSMiklos Szeredi return error; 4186bc27027aSMiklos Szeredi 4187bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4188bc27027aSMiklos Szeredi dget(new_dentry); 4189da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4190bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4191bc27027aSMiklos Szeredi else if (target) 4192bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4193bc27027aSMiklos Szeredi 4194bc27027aSMiklos Szeredi error = -EBUSY; 41957af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4196bc27027aSMiklos Szeredi goto out; 4197bc27027aSMiklos Szeredi 4198da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4199bc27027aSMiklos Szeredi error = -EMLINK; 4200da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4201bc27027aSMiklos Szeredi goto out; 4202da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4203da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4204da1ce067SMiklos Szeredi goto out; 4205da1ce067SMiklos Szeredi } 4206da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4207bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4208da1ce067SMiklos Szeredi if (!is_dir) { 4209bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4210bc27027aSMiklos Szeredi if (error) 4211bc27027aSMiklos Szeredi goto out; 4212da1ce067SMiklos Szeredi } 4213da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4214bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4215bc27027aSMiklos Szeredi if (error) 4216bc27027aSMiklos Szeredi goto out; 4217bc27027aSMiklos Szeredi } 42187177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4219520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4220520c8b16SMiklos Szeredi new_dir, new_dentry); 4221520c8b16SMiklos Szeredi } else { 42227177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4223520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4224520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4225520c8b16SMiklos Szeredi } 4226bc27027aSMiklos Szeredi if (error) 4227bc27027aSMiklos Szeredi goto out; 4228bc27027aSMiklos Szeredi 4229da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42301da177e4SLinus Torvalds if (is_dir) 4231bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4232bc27027aSMiklos Szeredi dont_mount(new_dentry); 42338ed936b5SEric W. Biederman detach_mounts(new_dentry); 4234bc27027aSMiklos Szeredi } 4235da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4236da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4237bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4238da1ce067SMiklos Szeredi else 4239da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4240da1ce067SMiklos Szeredi } 4241bc27027aSMiklos Szeredi out: 4242da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4243bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4244bc27027aSMiklos Szeredi else if (target) 4245bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4246bc27027aSMiklos Szeredi dput(new_dentry); 4247da1ce067SMiklos Szeredi if (!error) { 4248123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4249da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4250da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4251da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4252da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4253da1ce067SMiklos Szeredi } 4254da1ce067SMiklos Szeredi } 42550eeca283SRobert Love fsnotify_oldname_free(old_name); 42560eeca283SRobert Love 42571da177e4SLinus Torvalds return error; 42581da177e4SLinus Torvalds } 42594d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42601da177e4SLinus Torvalds 4261520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4262520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42631da177e4SLinus Torvalds { 42641da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42651da177e4SLinus Torvalds struct dentry *trap; 4266f5beed75SAl Viro struct path old_path, new_path; 4267f5beed75SAl Viro struct qstr old_last, new_last; 4268f5beed75SAl Viro int old_type, new_type; 42698e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 427091a27b2aSJeff Layton struct filename *from; 427191a27b2aSJeff Layton struct filename *to; 4272f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4273c6a94284SJeff Layton bool should_retry = false; 42742ad94ae6SAl Viro int error; 4275520c8b16SMiklos Szeredi 42760d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4277da1ce067SMiklos Szeredi return -EINVAL; 4278da1ce067SMiklos Szeredi 42790d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42800d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4281520c8b16SMiklos Szeredi return -EINVAL; 4282520c8b16SMiklos Szeredi 42830d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42840d7a8555SMiklos Szeredi return -EPERM; 42850d7a8555SMiklos Szeredi 4286f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4287f5beed75SAl Viro target_flags = 0; 4288f5beed75SAl Viro 4289c6a94284SJeff Layton retry: 4290f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4291f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 429291a27b2aSJeff Layton if (IS_ERR(from)) { 429391a27b2aSJeff Layton error = PTR_ERR(from); 42941da177e4SLinus Torvalds goto exit; 429591a27b2aSJeff Layton } 42961da177e4SLinus Torvalds 4297f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4298f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 429991a27b2aSJeff Layton if (IS_ERR(to)) { 430091a27b2aSJeff Layton error = PTR_ERR(to); 43011da177e4SLinus Torvalds goto exit1; 430291a27b2aSJeff Layton } 43031da177e4SLinus Torvalds 43041da177e4SLinus Torvalds error = -EXDEV; 4305f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43061da177e4SLinus Torvalds goto exit2; 43071da177e4SLinus Torvalds 43081da177e4SLinus Torvalds error = -EBUSY; 4309f5beed75SAl Viro if (old_type != LAST_NORM) 43101da177e4SLinus Torvalds goto exit2; 43111da177e4SLinus Torvalds 43120a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43130a7c3937SMiklos Szeredi error = -EEXIST; 4314f5beed75SAl Viro if (new_type != LAST_NORM) 43151da177e4SLinus Torvalds goto exit2; 43161da177e4SLinus Torvalds 4317f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4318c30dabfeSJan Kara if (error) 4319c30dabfeSJan Kara goto exit2; 4320c30dabfeSJan Kara 43218e6d782cSJ. Bruce Fields retry_deleg: 4322f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43231da177e4SLinus Torvalds 4324f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43251da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43261da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43271da177e4SLinus Torvalds goto exit3; 43281da177e4SLinus Torvalds /* source must exist */ 43291da177e4SLinus Torvalds error = -ENOENT; 4330b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43311da177e4SLinus Torvalds goto exit4; 4332f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43331da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43341da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43351da177e4SLinus Torvalds goto exit4; 43360a7c3937SMiklos Szeredi error = -EEXIST; 43370a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43380a7c3937SMiklos Szeredi goto exit5; 4339da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4340da1ce067SMiklos Szeredi error = -ENOENT; 4341da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4342da1ce067SMiklos Szeredi goto exit5; 4343da1ce067SMiklos Szeredi 4344da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4345da1ce067SMiklos Szeredi error = -ENOTDIR; 4346f5beed75SAl Viro if (new_last.name[new_last.len]) 4347da1ce067SMiklos Szeredi goto exit5; 4348da1ce067SMiklos Szeredi } 4349da1ce067SMiklos Szeredi } 43500a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43510a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43520a7c3937SMiklos Szeredi error = -ENOTDIR; 4353f5beed75SAl Viro if (old_last.name[old_last.len]) 43540a7c3937SMiklos Szeredi goto exit5; 4355f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43560a7c3937SMiklos Szeredi goto exit5; 43570a7c3937SMiklos Szeredi } 43580a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43590a7c3937SMiklos Szeredi error = -EINVAL; 43600a7c3937SMiklos Szeredi if (old_dentry == trap) 43610a7c3937SMiklos Szeredi goto exit5; 43621da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4363da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43641da177e4SLinus Torvalds error = -ENOTEMPTY; 43651da177e4SLinus Torvalds if (new_dentry == trap) 43661da177e4SLinus Torvalds goto exit5; 43671da177e4SLinus Torvalds 4368f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4369f5beed75SAl Viro &new_path, new_dentry, flags); 4370be6d3e56SKentaro Takeda if (error) 4371c30dabfeSJan Kara goto exit5; 4372f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4373f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4374520c8b16SMiklos Szeredi &delegated_inode, flags); 43751da177e4SLinus Torvalds exit5: 43761da177e4SLinus Torvalds dput(new_dentry); 43771da177e4SLinus Torvalds exit4: 43781da177e4SLinus Torvalds dput(old_dentry); 43791da177e4SLinus Torvalds exit3: 4380f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 43818e6d782cSJ. Bruce Fields if (delegated_inode) { 43828e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43838e6d782cSJ. Bruce Fields if (!error) 43848e6d782cSJ. Bruce Fields goto retry_deleg; 43858e6d782cSJ. Bruce Fields } 4386f5beed75SAl Viro mnt_drop_write(old_path.mnt); 43871da177e4SLinus Torvalds exit2: 4388c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4389c6a94284SJeff Layton should_retry = true; 4390f5beed75SAl Viro path_put(&new_path); 43912ad94ae6SAl Viro putname(to); 43921da177e4SLinus Torvalds exit1: 4393f5beed75SAl Viro path_put(&old_path); 43941da177e4SLinus Torvalds putname(from); 4395c6a94284SJeff Layton if (should_retry) { 4396c6a94284SJeff Layton should_retry = false; 4397c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4398c6a94284SJeff Layton goto retry; 4399c6a94284SJeff Layton } 44002ad94ae6SAl Viro exit: 44011da177e4SLinus Torvalds return error; 44021da177e4SLinus Torvalds } 44031da177e4SLinus Torvalds 4404520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4405520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4406520c8b16SMiklos Szeredi { 4407520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4408520c8b16SMiklos Szeredi } 4409520c8b16SMiklos Szeredi 4410a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44115590ff0dSUlrich Drepper { 4412520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44135590ff0dSUlrich Drepper } 44145590ff0dSUlrich Drepper 4415787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4416787fb6bcSMiklos Szeredi { 4417787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4418787fb6bcSMiklos Szeredi if (error) 4419787fb6bcSMiklos Szeredi return error; 4420787fb6bcSMiklos Szeredi 4421787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4422787fb6bcSMiklos Szeredi return -EPERM; 4423787fb6bcSMiklos Szeredi 4424787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4425787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4426787fb6bcSMiklos Szeredi } 4427787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4428787fb6bcSMiklos Szeredi 44295d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44301da177e4SLinus Torvalds { 44315d826c84SAl Viro int len = PTR_ERR(link); 44321da177e4SLinus Torvalds if (IS_ERR(link)) 44331da177e4SLinus Torvalds goto out; 44341da177e4SLinus Torvalds 44351da177e4SLinus Torvalds len = strlen(link); 44361da177e4SLinus Torvalds if (len > (unsigned) buflen) 44371da177e4SLinus Torvalds len = buflen; 44381da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44391da177e4SLinus Torvalds len = -EFAULT; 44401da177e4SLinus Torvalds out: 44411da177e4SLinus Torvalds return len; 44421da177e4SLinus Torvalds } 44435d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44441da177e4SLinus Torvalds 44451da177e4SLinus Torvalds /* 44461da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44471da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44481da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44491da177e4SLinus Torvalds */ 44501da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44511da177e4SLinus Torvalds { 4452cc314eefSLinus Torvalds void *cookie; 44535f2c4179SAl Viro struct inode *inode = d_inode(dentry); 44545f2c4179SAl Viro const char *link = inode->i_link; 4455694a1764SMarcin Slusarz int res; 4456cc314eefSLinus Torvalds 4457d4dee48bSAl Viro if (!link) { 44585f2c4179SAl Viro link = inode->i_op->follow_link(dentry, &cookie); 4459680baacbSAl Viro if (IS_ERR(link)) 4460680baacbSAl Viro return PTR_ERR(link); 4461d4dee48bSAl Viro } 4462680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 44635f2c4179SAl Viro if (inode->i_op->put_link) 44645f2c4179SAl Viro inode->i_op->put_link(inode, cookie); 4465694a1764SMarcin Slusarz return res; 44661da177e4SLinus Torvalds } 44674d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44681da177e4SLinus Torvalds 44691da177e4SLinus Torvalds /* get the link contents into pagecache */ 44701da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44711da177e4SLinus Torvalds { 4472ebd09abbSDuane Griffin char *kaddr; 44731da177e4SLinus Torvalds struct page *page; 44741da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4475090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44761da177e4SLinus Torvalds if (IS_ERR(page)) 44776fe6900eSNick Piggin return (char*)page; 44781da177e4SLinus Torvalds *ppage = page; 4479ebd09abbSDuane Griffin kaddr = kmap(page); 4480ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4481ebd09abbSDuane Griffin return kaddr; 44821da177e4SLinus Torvalds } 44831da177e4SLinus Torvalds 44841da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44851da177e4SLinus Torvalds { 44861da177e4SLinus Torvalds struct page *page = NULL; 44875d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44881da177e4SLinus Torvalds if (page) { 44891da177e4SLinus Torvalds kunmap(page); 44901da177e4SLinus Torvalds page_cache_release(page); 44911da177e4SLinus Torvalds } 44921da177e4SLinus Torvalds return res; 44931da177e4SLinus Torvalds } 44944d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44951da177e4SLinus Torvalds 44966e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 44971da177e4SLinus Torvalds { 4498cc314eefSLinus Torvalds struct page *page = NULL; 4499680baacbSAl Viro char *res = page_getlink(dentry, &page); 4500680baacbSAl Viro if (!IS_ERR(res)) 4501680baacbSAl Viro *cookie = page; 4502680baacbSAl Viro return res; 45031da177e4SLinus Torvalds } 45044d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45051da177e4SLinus Torvalds 45065f2c4179SAl Viro void page_put_link(struct inode *unused, void *cookie) 45071da177e4SLinus Torvalds { 4508cc314eefSLinus Torvalds struct page *page = cookie; 45091da177e4SLinus Torvalds kunmap(page); 45101da177e4SLinus Torvalds page_cache_release(page); 45111da177e4SLinus Torvalds } 45124d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45131da177e4SLinus Torvalds 451454566b2cSNick Piggin /* 451554566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 451654566b2cSNick Piggin */ 451754566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45181da177e4SLinus Torvalds { 45191da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45200adb25d2SKirill Korotaev struct page *page; 4521afddba49SNick Piggin void *fsdata; 4522beb497abSDmitriy Monakhov int err; 45231da177e4SLinus Torvalds char *kaddr; 452454566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 452554566b2cSNick Piggin if (nofs) 452654566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45271da177e4SLinus Torvalds 45287e53cac4SNeilBrown retry: 4529afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 453054566b2cSNick Piggin flags, &page, &fsdata); 45311da177e4SLinus Torvalds if (err) 4532afddba49SNick Piggin goto fail; 4533afddba49SNick Piggin 4534e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45351da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4536e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4537afddba49SNick Piggin 4538afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4539afddba49SNick Piggin page, fsdata); 45401da177e4SLinus Torvalds if (err < 0) 45411da177e4SLinus Torvalds goto fail; 4542afddba49SNick Piggin if (err < len-1) 4543afddba49SNick Piggin goto retry; 4544afddba49SNick Piggin 45451da177e4SLinus Torvalds mark_inode_dirty(inode); 45461da177e4SLinus Torvalds return 0; 45471da177e4SLinus Torvalds fail: 45481da177e4SLinus Torvalds return err; 45491da177e4SLinus Torvalds } 45504d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45511da177e4SLinus Torvalds 45520adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45530adb25d2SKirill Korotaev { 45540adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 455554566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45560adb25d2SKirill Korotaev } 45574d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45580adb25d2SKirill Korotaev 455992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45601da177e4SLinus Torvalds .readlink = generic_readlink, 45611da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45621da177e4SLinus Torvalds .put_link = page_put_link, 45631da177e4SLinus Torvalds }; 45641da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4565