11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 498caa85634SAl Viro union { 4991f55a6ecSAl Viro struct qstr last; 500caa85634SAl Viro struct path link; 501caa85634SAl Viro }; 5021f55a6ecSAl Viro struct path root; 5031f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5041f55a6ecSAl Viro unsigned int flags; 5051f55a6ecSAl Viro unsigned seq, m_seq; 5061f55a6ecSAl Viro int last_type; 5071f55a6ecSAl Viro unsigned depth; 5085e53084dSAl Viro struct file *base; 509697fc6caSAl Viro struct saved { 510697fc6caSAl Viro struct path link; 511697fc6caSAl Viro void *cookie; 512697fc6caSAl Viro const char *name; 513894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5141f55a6ecSAl Viro }; 5151f55a6ecSAl Viro 516894bc8c4SAl Viro static void set_nameidata(struct nameidata *nd) 517894bc8c4SAl Viro { 518894bc8c4SAl Viro nd->stack = nd->internal; 519894bc8c4SAl Viro } 520894bc8c4SAl Viro 521894bc8c4SAl Viro static void restore_nameidata(struct nameidata *nd) 522894bc8c4SAl Viro { 523894bc8c4SAl Viro if (nd->stack != nd->internal) { 524894bc8c4SAl Viro kfree(nd->stack); 525894bc8c4SAl Viro nd->stack = nd->internal; 526894bc8c4SAl Viro } 527894bc8c4SAl Viro } 528894bc8c4SAl Viro 529894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 530894bc8c4SAl Viro { 531894bc8c4SAl Viro struct saved *p = kmalloc((MAXSYMLINKS + 1) * sizeof(struct saved), 532894bc8c4SAl Viro GFP_KERNEL); 533894bc8c4SAl Viro if (unlikely(!p)) 534894bc8c4SAl Viro return -ENOMEM; 535894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 536894bc8c4SAl Viro nd->stack = p; 537894bc8c4SAl Viro return 0; 538894bc8c4SAl Viro } 539894bc8c4SAl Viro 540894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 541894bc8c4SAl Viro { 542da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 543894bc8c4SAl Viro return 0; 544894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 545894bc8c4SAl Viro return 0; 546894bc8c4SAl Viro return __nd_alloc_stack(nd); 547894bc8c4SAl Viro } 548894bc8c4SAl Viro 54919660af7SAl Viro /* 55031e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 55119660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 55219660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 55319660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 55419660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 55519660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 55619660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 55719660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 55831e6b01fSNick Piggin */ 55931e6b01fSNick Piggin 56031e6b01fSNick Piggin /** 56119660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 56219660af7SAl Viro * @nd: nameidata pathwalk data 56319660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 56439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 56531e6b01fSNick Piggin * 56619660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 56719660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 56819660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 56931e6b01fSNick Piggin */ 57019660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 57131e6b01fSNick Piggin { 57231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 57331e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 57431e6b01fSNick Piggin 57531e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 576e5c832d5SLinus Torvalds 577e5c832d5SLinus Torvalds /* 57848a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 57948a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 58048a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 58148a066e7SAl Viro * before returning. Do vfsmount first; if dentry 58248a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 58348a066e7SAl Viro * and rely on dput(NULL) being a no-op. 584e5c832d5SLinus Torvalds */ 58548a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 586e5c832d5SLinus Torvalds return -ECHILD; 587e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 58815570086SLinus Torvalds 58948a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 59048a066e7SAl Viro nd->path.dentry = NULL; 591d870b4a1SAl Viro goto out; 59248a066e7SAl Viro } 59348a066e7SAl Viro 59415570086SLinus Torvalds /* 59515570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 59615570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 59715570086SLinus Torvalds * 59815570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 59915570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 60015570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 60115570086SLinus Torvalds * since we checked the sequence number of the parent after we got 60215570086SLinus Torvalds * the child sequence number. So we know the parent must still 60315570086SLinus Torvalds * be valid if the child sequence number is still valid. 60415570086SLinus Torvalds */ 60519660af7SAl Viro if (!dentry) { 606e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 607e5c832d5SLinus Torvalds goto out; 60819660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 60919660af7SAl Viro } else { 610e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 611e5c832d5SLinus Torvalds goto out; 612e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 613e5c832d5SLinus Torvalds goto drop_dentry; 61419660af7SAl Viro } 615e5c832d5SLinus Torvalds 616e5c832d5SLinus Torvalds /* 617e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 618e5c832d5SLinus Torvalds * still valid and get it if required. 619e5c832d5SLinus Torvalds */ 620e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 621e5c832d5SLinus Torvalds spin_lock(&fs->lock); 622e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 623e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 62431e6b01fSNick Piggin path_get(&nd->root); 62531e6b01fSNick Piggin spin_unlock(&fs->lock); 62631e6b01fSNick Piggin } 62731e6b01fSNick Piggin 6288b61e74fSAl Viro rcu_read_unlock(); 62931e6b01fSNick Piggin return 0; 63019660af7SAl Viro 631e5c832d5SLinus Torvalds unlock_and_drop_dentry: 63231e6b01fSNick Piggin spin_unlock(&fs->lock); 633e5c832d5SLinus Torvalds drop_dentry: 6348b61e74fSAl Viro rcu_read_unlock(); 635e5c832d5SLinus Torvalds dput(dentry); 636d0d27277SLinus Torvalds goto drop_root_mnt; 637e5c832d5SLinus Torvalds out: 6388b61e74fSAl Viro rcu_read_unlock(); 639d0d27277SLinus Torvalds drop_root_mnt: 640d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 641d0d27277SLinus Torvalds nd->root.mnt = NULL; 64231e6b01fSNick Piggin return -ECHILD; 64331e6b01fSNick Piggin } 64431e6b01fSNick Piggin 6454ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 64634286d66SNick Piggin { 6474ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 64834286d66SNick Piggin } 64934286d66SNick Piggin 6509f1fafeeSAl Viro /** 6519f1fafeeSAl Viro * complete_walk - successful completion of path walk 6529f1fafeeSAl Viro * @nd: pointer nameidata 65339159de2SJeff Layton * 6549f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6559f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6569f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6579f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6589f1fafeeSAl Viro * need to drop nd->path. 65939159de2SJeff Layton */ 6609f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 66139159de2SJeff Layton { 66216c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 66339159de2SJeff Layton int status; 66439159de2SJeff Layton 6659f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6669f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6679f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6689f1fafeeSAl Viro nd->root.mnt = NULL; 66915570086SLinus Torvalds 67048a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6718b61e74fSAl Viro rcu_read_unlock(); 67248a066e7SAl Viro return -ECHILD; 67348a066e7SAl Viro } 674e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6758b61e74fSAl Viro rcu_read_unlock(); 67648a066e7SAl Viro mntput(nd->path.mnt); 6779f1fafeeSAl Viro return -ECHILD; 6789f1fafeeSAl Viro } 679e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6808b61e74fSAl Viro rcu_read_unlock(); 681e5c832d5SLinus Torvalds dput(dentry); 68248a066e7SAl Viro mntput(nd->path.mnt); 683e5c832d5SLinus Torvalds return -ECHILD; 684e5c832d5SLinus Torvalds } 6858b61e74fSAl Viro rcu_read_unlock(); 6869f1fafeeSAl Viro } 6879f1fafeeSAl Viro 68816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 68939159de2SJeff Layton return 0; 69039159de2SJeff Layton 691ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 69216c2cd71SAl Viro return 0; 69316c2cd71SAl Viro 694ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 69539159de2SJeff Layton if (status > 0) 69639159de2SJeff Layton return 0; 69739159de2SJeff Layton 69816c2cd71SAl Viro if (!status) 69939159de2SJeff Layton status = -ESTALE; 70016c2cd71SAl Viro 7019f1fafeeSAl Viro path_put(&nd->path); 70239159de2SJeff Layton return status; 70339159de2SJeff Layton } 70439159de2SJeff Layton 7052a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 7062a737871SAl Viro { 707f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 7082a737871SAl Viro } 7092a737871SAl Viro 7107bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 71131e6b01fSNick Piggin { 71231e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7137bd88377SAl Viro unsigned seq, res; 714c28cc364SNick Piggin 715c28cc364SNick Piggin do { 716c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 71731e6b01fSNick Piggin nd->root = fs->root; 7187bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 719c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7207bd88377SAl Viro return res; 72131e6b01fSNick Piggin } 72231e6b01fSNick Piggin 7231d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 724051d3812SIan Kent { 725051d3812SIan Kent dput(path->dentry); 7264ac91378SJan Blunck if (path->mnt != nd->path.mnt) 727051d3812SIan Kent mntput(path->mnt); 728051d3812SIan Kent } 729051d3812SIan Kent 7307b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7317b9337aaSNick Piggin struct nameidata *nd) 732051d3812SIan Kent { 73331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7344ac91378SJan Blunck dput(nd->path.dentry); 73531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7364ac91378SJan Blunck mntput(nd->path.mnt); 7379a229683SHuang Shijie } 73831e6b01fSNick Piggin nd->path.mnt = path->mnt; 7394ac91378SJan Blunck nd->path.dentry = path->dentry; 740051d3812SIan Kent } 741051d3812SIan Kent 742b5fb63c1SChristoph Hellwig /* 743b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 744b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 745b5fb63c1SChristoph Hellwig */ 746b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 747b5fb63c1SChristoph Hellwig { 748b5fb63c1SChristoph Hellwig path_put(&nd->path); 749b5fb63c1SChristoph Hellwig 750b5fb63c1SChristoph Hellwig nd->path = *path; 751b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 752b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 753b5fb63c1SChristoph Hellwig } 754b5fb63c1SChristoph Hellwig 755b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 756574197e0SAl Viro { 75721c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 758b9ff4429SAl Viro struct inode *inode = last->link.dentry->d_inode; 759b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 760b9ff4429SAl Viro inode->i_op->put_link(last->link.dentry, last->cookie); 761b9ff4429SAl Viro path_put(&last->link); 762574197e0SAl Viro } 763574197e0SAl Viro 764561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 765561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 766800179c9SKees Cook 767800179c9SKees Cook /** 768800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 769800179c9SKees Cook * @link: The path of the symlink 77055852635SRandy Dunlap * @nd: nameidata pathwalk data 771800179c9SKees Cook * 772800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 773800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 774800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 775800179c9SKees Cook * processes from failing races against path names that may change out 776800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 777800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 778800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 779800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 780800179c9SKees Cook * 781800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 782800179c9SKees Cook */ 783800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 784800179c9SKees Cook { 785800179c9SKees Cook const struct inode *inode; 786800179c9SKees Cook const struct inode *parent; 787800179c9SKees Cook 788800179c9SKees Cook if (!sysctl_protected_symlinks) 789800179c9SKees Cook return 0; 790800179c9SKees Cook 791800179c9SKees Cook /* Allowed if owner and follower match. */ 792800179c9SKees Cook inode = link->dentry->d_inode; 79381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 794800179c9SKees Cook return 0; 795800179c9SKees Cook 796800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 797800179c9SKees Cook parent = nd->path.dentry->d_inode; 798800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 799800179c9SKees Cook return 0; 800800179c9SKees Cook 801800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 80281abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 803800179c9SKees Cook return 0; 804800179c9SKees Cook 805ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 806800179c9SKees Cook path_put_conditional(link, nd); 807800179c9SKees Cook path_put(&nd->path); 808800179c9SKees Cook return -EACCES; 809800179c9SKees Cook } 810800179c9SKees Cook 811800179c9SKees Cook /** 812800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 813800179c9SKees Cook * @inode: the source inode to hardlink from 814800179c9SKees Cook * 815800179c9SKees Cook * Return false if at least one of the following conditions: 816800179c9SKees Cook * - inode is not a regular file 817800179c9SKees Cook * - inode is setuid 818800179c9SKees Cook * - inode is setgid and group-exec 819800179c9SKees Cook * - access failure for read and write 820800179c9SKees Cook * 821800179c9SKees Cook * Otherwise returns true. 822800179c9SKees Cook */ 823800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 824800179c9SKees Cook { 825800179c9SKees Cook umode_t mode = inode->i_mode; 826800179c9SKees Cook 827800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 828800179c9SKees Cook if (!S_ISREG(mode)) 829800179c9SKees Cook return false; 830800179c9SKees Cook 831800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 832800179c9SKees Cook if (mode & S_ISUID) 833800179c9SKees Cook return false; 834800179c9SKees Cook 835800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 836800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 837800179c9SKees Cook return false; 838800179c9SKees Cook 839800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 840800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 841800179c9SKees Cook return false; 842800179c9SKees Cook 843800179c9SKees Cook return true; 844800179c9SKees Cook } 845800179c9SKees Cook 846800179c9SKees Cook /** 847800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 848800179c9SKees Cook * @link: the source to hardlink from 849800179c9SKees Cook * 850800179c9SKees Cook * Block hardlink when all of: 851800179c9SKees Cook * - sysctl_protected_hardlinks enabled 852800179c9SKees Cook * - fsuid does not match inode 853800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 854800179c9SKees Cook * - not CAP_FOWNER 855800179c9SKees Cook * 856800179c9SKees Cook * Returns 0 if successful, -ve on error. 857800179c9SKees Cook */ 858800179c9SKees Cook static int may_linkat(struct path *link) 859800179c9SKees Cook { 860800179c9SKees Cook const struct cred *cred; 861800179c9SKees Cook struct inode *inode; 862800179c9SKees Cook 863800179c9SKees Cook if (!sysctl_protected_hardlinks) 864800179c9SKees Cook return 0; 865800179c9SKees Cook 866800179c9SKees Cook cred = current_cred(); 867800179c9SKees Cook inode = link->dentry->d_inode; 868800179c9SKees Cook 869800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 870800179c9SKees Cook * otherwise, it must be a safe source. 871800179c9SKees Cook */ 87281abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 873800179c9SKees Cook capable(CAP_FOWNER)) 874800179c9SKees Cook return 0; 875800179c9SKees Cook 876a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 877800179c9SKees Cook return -EPERM; 878800179c9SKees Cook } 879800179c9SKees Cook 8803b2e7f75SAl Viro static __always_inline 8813b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8821da177e4SLinus Torvalds { 8833b2e7f75SAl Viro struct saved *last = nd->stack + nd->depth; 8843b2e7f75SAl Viro struct dentry *dentry = nd->link.dentry; 8850a959df5SAl Viro struct inode *inode = dentry->d_inode; 8866d7b5aaeSAl Viro int error; 8870a959df5SAl Viro const char *res; 8881da177e4SLinus Torvalds 889844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 890844a3917SAl Viro 8913b2e7f75SAl Viro if (nd->link.mnt == nd->path.mnt) 8923b2e7f75SAl Viro mntget(nd->link.mnt); 8930e794589SAl Viro 894894bc8c4SAl Viro if (unlikely(current->total_link_count >= MAXSYMLINKS)) { 8953b2e7f75SAl Viro path_put(&nd->path); 8963b2e7f75SAl Viro path_put(&nd->link); 8973b2e7f75SAl Viro return ERR_PTR(-ELOOP); 8983b2e7f75SAl Viro } 8993b2e7f75SAl Viro 9003b2e7f75SAl Viro last->link = nd->link; 9013b2e7f75SAl Viro last->cookie = NULL; 9026d7b5aaeSAl Viro 903574197e0SAl Viro cond_resched(); 904574197e0SAl Viro current->total_link_count++; 905574197e0SAl Viro 9063b2e7f75SAl Viro touch_atime(&last->link); 907cd4e91d3SAl Viro 90837882db0SNeilBrown error = security_inode_follow_link(dentry); 9090a959df5SAl Viro res = ERR_PTR(error); 9106d7b5aaeSAl Viro if (error) 9110a959df5SAl Viro goto out; 91236f3b4f6SAl Viro 91386acdca1SAl Viro nd->last_type = LAST_BIND; 914d4dee48bSAl Viro res = inode->i_link; 915d4dee48bSAl Viro if (!res) { 9163b2e7f75SAl Viro res = inode->i_op->follow_link(dentry, &last->cookie, nd); 9170a959df5SAl Viro if (IS_ERR(res)) { 9180a959df5SAl Viro out: 9190a959df5SAl Viro path_put(&nd->path); 9203b2e7f75SAl Viro path_put(&last->link); 9210fd889d5SAl Viro return res; 9220a959df5SAl Viro } 923d4dee48bSAl Viro } 9240fd889d5SAl Viro nd->depth++; 9250a959df5SAl Viro return res; 9260a959df5SAl Viro } 9276d7b5aaeSAl Viro 92831e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 92931e6b01fSNick Piggin { 9300714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9310714a533SAl Viro struct mount *parent; 93231e6b01fSNick Piggin struct dentry *mountpoint; 93331e6b01fSNick Piggin 9340714a533SAl Viro parent = mnt->mnt_parent; 9350714a533SAl Viro if (&parent->mnt == path->mnt) 93631e6b01fSNick Piggin return 0; 937a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 93831e6b01fSNick Piggin path->dentry = mountpoint; 9390714a533SAl Viro path->mnt = &parent->mnt; 94031e6b01fSNick Piggin return 1; 94131e6b01fSNick Piggin } 94231e6b01fSNick Piggin 943f015f126SDavid Howells /* 944f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 945f015f126SDavid Howells * 946f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 947f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 948f015f126SDavid Howells * Up is towards /. 949f015f126SDavid Howells * 950f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 951f015f126SDavid Howells * root. 952f015f126SDavid Howells */ 953bab77ebfSAl Viro int follow_up(struct path *path) 9541da177e4SLinus Torvalds { 9550714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9560714a533SAl Viro struct mount *parent; 9571da177e4SLinus Torvalds struct dentry *mountpoint; 95899b7db7bSNick Piggin 95948a066e7SAl Viro read_seqlock_excl(&mount_lock); 9600714a533SAl Viro parent = mnt->mnt_parent; 9613c0a6163SAl Viro if (parent == mnt) { 96248a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9631da177e4SLinus Torvalds return 0; 9641da177e4SLinus Torvalds } 9650714a533SAl Viro mntget(&parent->mnt); 966a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 96748a066e7SAl Viro read_sequnlock_excl(&mount_lock); 968bab77ebfSAl Viro dput(path->dentry); 969bab77ebfSAl Viro path->dentry = mountpoint; 970bab77ebfSAl Viro mntput(path->mnt); 9710714a533SAl Viro path->mnt = &parent->mnt; 9721da177e4SLinus Torvalds return 1; 9731da177e4SLinus Torvalds } 9744d359507SAl Viro EXPORT_SYMBOL(follow_up); 9751da177e4SLinus Torvalds 976b5c84bf6SNick Piggin /* 9779875cf80SDavid Howells * Perform an automount 9789875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9799875cf80SDavid Howells * were called with. 9801da177e4SLinus Torvalds */ 9819875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9829875cf80SDavid Howells bool *need_mntput) 98331e6b01fSNick Piggin { 9849875cf80SDavid Howells struct vfsmount *mnt; 985ea5b778aSDavid Howells int err; 9869875cf80SDavid Howells 9879875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9889875cf80SDavid Howells return -EREMOTE; 9899875cf80SDavid Howells 9900ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9910ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9920ec26fd0SMiklos Szeredi * the name. 9930ec26fd0SMiklos Szeredi * 9940ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9955a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9960ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9970ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9980ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9990ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 10005a30d8a2SDavid Howells */ 10015a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 1002d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 10035a30d8a2SDavid Howells path->dentry->d_inode) 10049875cf80SDavid Howells return -EISDIR; 10050ec26fd0SMiklos Szeredi 10069875cf80SDavid Howells current->total_link_count++; 10079875cf80SDavid Howells if (current->total_link_count >= 40) 10089875cf80SDavid Howells return -ELOOP; 10099875cf80SDavid Howells 10109875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 10119875cf80SDavid Howells if (IS_ERR(mnt)) { 10129875cf80SDavid Howells /* 10139875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 10149875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 10159875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 10169875cf80SDavid Howells * 10179875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10189875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10199875cf80SDavid Howells * the path is inaccessible and we should say so. 10209875cf80SDavid Howells */ 102149084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 10229875cf80SDavid Howells return -EREMOTE; 10239875cf80SDavid Howells return PTR_ERR(mnt); 102431e6b01fSNick Piggin } 1025ea5b778aSDavid Howells 10269875cf80SDavid Howells if (!mnt) /* mount collision */ 10279875cf80SDavid Howells return 0; 10289875cf80SDavid Howells 10298aef1884SAl Viro if (!*need_mntput) { 10308aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10318aef1884SAl Viro mntget(path->mnt); 10328aef1884SAl Viro *need_mntput = true; 10338aef1884SAl Viro } 103419a167afSAl Viro err = finish_automount(mnt, path); 1035ea5b778aSDavid Howells 1036ea5b778aSDavid Howells switch (err) { 1037ea5b778aSDavid Howells case -EBUSY: 1038ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 103919a167afSAl Viro return 0; 1040ea5b778aSDavid Howells case 0: 10418aef1884SAl Viro path_put(path); 10429875cf80SDavid Howells path->mnt = mnt; 10439875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10449875cf80SDavid Howells return 0; 104519a167afSAl Viro default: 104619a167afSAl Viro return err; 10479875cf80SDavid Howells } 104819a167afSAl Viro 1049ea5b778aSDavid Howells } 10509875cf80SDavid Howells 10519875cf80SDavid Howells /* 10529875cf80SDavid Howells * Handle a dentry that is managed in some way. 1053cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10549875cf80SDavid Howells * - Flagged as mountpoint 10559875cf80SDavid Howells * - Flagged as automount point 10569875cf80SDavid Howells * 10579875cf80SDavid Howells * This may only be called in refwalk mode. 10589875cf80SDavid Howells * 10599875cf80SDavid Howells * Serialization is taken care of in namespace.c 10609875cf80SDavid Howells */ 10619875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10629875cf80SDavid Howells { 10638aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10649875cf80SDavid Howells unsigned managed; 10659875cf80SDavid Howells bool need_mntput = false; 10668aef1884SAl Viro int ret = 0; 10679875cf80SDavid Howells 10689875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10699875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10709875cf80SDavid Howells * the components of that value change under us */ 10719875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10729875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10739875cf80SDavid Howells unlikely(managed != 0)) { 1074cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1075cc53ce53SDavid Howells * being held. */ 1076cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1077cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1078cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10791aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1080cc53ce53SDavid Howells if (ret < 0) 10818aef1884SAl Viro break; 1082cc53ce53SDavid Howells } 1083cc53ce53SDavid Howells 10849875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10859875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10869875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10879875cf80SDavid Howells if (mounted) { 10889875cf80SDavid Howells dput(path->dentry); 10899875cf80SDavid Howells if (need_mntput) 1090463ffb2eSAl Viro mntput(path->mnt); 1091463ffb2eSAl Viro path->mnt = mounted; 1092463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10939875cf80SDavid Howells need_mntput = true; 10949875cf80SDavid Howells continue; 1095463ffb2eSAl Viro } 1096463ffb2eSAl Viro 10979875cf80SDavid Howells /* Something is mounted on this dentry in another 10989875cf80SDavid Howells * namespace and/or whatever was mounted there in this 109948a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 110048a066e7SAl Viro * get it */ 11011da177e4SLinus Torvalds } 11029875cf80SDavid Howells 11039875cf80SDavid Howells /* Handle an automount point */ 11049875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 11059875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 11069875cf80SDavid Howells if (ret < 0) 11078aef1884SAl Viro break; 11089875cf80SDavid Howells continue; 11099875cf80SDavid Howells } 11109875cf80SDavid Howells 11119875cf80SDavid Howells /* We didn't change the current path point */ 11129875cf80SDavid Howells break; 11139875cf80SDavid Howells } 11148aef1884SAl Viro 11158aef1884SAl Viro if (need_mntput && path->mnt == mnt) 11168aef1884SAl Viro mntput(path->mnt); 11178aef1884SAl Viro if (ret == -EISDIR) 11188aef1884SAl Viro ret = 0; 1119a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 11201da177e4SLinus Torvalds } 11211da177e4SLinus Torvalds 1122cc53ce53SDavid Howells int follow_down_one(struct path *path) 11231da177e4SLinus Torvalds { 11241da177e4SLinus Torvalds struct vfsmount *mounted; 11251da177e4SLinus Torvalds 11261c755af4SAl Viro mounted = lookup_mnt(path); 11271da177e4SLinus Torvalds if (mounted) { 11289393bd07SAl Viro dput(path->dentry); 11299393bd07SAl Viro mntput(path->mnt); 11309393bd07SAl Viro path->mnt = mounted; 11319393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11321da177e4SLinus Torvalds return 1; 11331da177e4SLinus Torvalds } 11341da177e4SLinus Torvalds return 0; 11351da177e4SLinus Torvalds } 11364d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11371da177e4SLinus Torvalds 1138b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 113962a7375eSIan Kent { 1140b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1141b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 114262a7375eSIan Kent } 114362a7375eSIan Kent 11449875cf80SDavid Howells /* 1145287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1146287548e4SAl Viro * we meet a managed dentry that would need blocking. 11479875cf80SDavid Howells */ 11489875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1149287548e4SAl Viro struct inode **inode) 11509875cf80SDavid Howells { 115162a7375eSIan Kent for (;;) { 1152c7105365SAl Viro struct mount *mounted; 115362a7375eSIan Kent /* 115462a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 115562a7375eSIan Kent * that wants to block transit. 115662a7375eSIan Kent */ 1157b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1158b8faf035SNeilBrown case -ECHILD: 1159b8faf035SNeilBrown default: 1160ab90911fSDavid Howells return false; 1161b8faf035SNeilBrown case -EISDIR: 1162b8faf035SNeilBrown return true; 1163b8faf035SNeilBrown case 0: 1164b8faf035SNeilBrown break; 1165b8faf035SNeilBrown } 116662a7375eSIan Kent 116762a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1168b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 116962a7375eSIan Kent 1170474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11719875cf80SDavid Howells if (!mounted) 11729875cf80SDavid Howells break; 1173c7105365SAl Viro path->mnt = &mounted->mnt; 1174c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1175a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11769875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 117759430262SLinus Torvalds /* 117859430262SLinus Torvalds * Update the inode too. We don't need to re-check the 117959430262SLinus Torvalds * dentry sequence number here after this d_inode read, 118059430262SLinus Torvalds * because a mount-point is always pinned. 118159430262SLinus Torvalds */ 118259430262SLinus Torvalds *inode = path->dentry->d_inode; 11839875cf80SDavid Howells } 1184f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1185b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1186287548e4SAl Viro } 1187287548e4SAl Viro 118831e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 118931e6b01fSNick Piggin { 11904023bfc9SAl Viro struct inode *inode = nd->inode; 11917bd88377SAl Viro if (!nd->root.mnt) 119231e6b01fSNick Piggin set_root_rcu(nd); 119331e6b01fSNick Piggin 119431e6b01fSNick Piggin while (1) { 119531e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 119631e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 119731e6b01fSNick Piggin break; 119831e6b01fSNick Piggin } 119931e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 120031e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 120131e6b01fSNick Piggin struct dentry *parent = old->d_parent; 120231e6b01fSNick Piggin unsigned seq; 120331e6b01fSNick Piggin 12044023bfc9SAl Viro inode = parent->d_inode; 120531e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 120631e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1207ef7562d5SAl Viro goto failed; 120831e6b01fSNick Piggin nd->path.dentry = parent; 120931e6b01fSNick Piggin nd->seq = seq; 121031e6b01fSNick Piggin break; 121131e6b01fSNick Piggin } 121231e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 121331e6b01fSNick Piggin break; 12144023bfc9SAl Viro inode = nd->path.dentry->d_inode; 121531e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 121631e6b01fSNick Piggin } 1217b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1218b37199e6SAl Viro struct mount *mounted; 1219b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1220b37199e6SAl Viro if (!mounted) 1221b37199e6SAl Viro break; 1222b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1223b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12244023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1225b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1226f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1227b37199e6SAl Viro goto failed; 1228b37199e6SAl Viro } 12294023bfc9SAl Viro nd->inode = inode; 123031e6b01fSNick Piggin return 0; 1231ef7562d5SAl Viro 1232ef7562d5SAl Viro failed: 1233ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 12345b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1235ef7562d5SAl Viro nd->root.mnt = NULL; 12368b61e74fSAl Viro rcu_read_unlock(); 1237ef7562d5SAl Viro return -ECHILD; 123831e6b01fSNick Piggin } 123931e6b01fSNick Piggin 12409875cf80SDavid Howells /* 1241cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1242cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1243cc53ce53SDavid Howells * caller is permitted to proceed or not. 1244cc53ce53SDavid Howells */ 12457cc90cc3SAl Viro int follow_down(struct path *path) 1246cc53ce53SDavid Howells { 1247cc53ce53SDavid Howells unsigned managed; 1248cc53ce53SDavid Howells int ret; 1249cc53ce53SDavid Howells 1250cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1251cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1252cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1253cc53ce53SDavid Howells * being held. 1254cc53ce53SDavid Howells * 1255cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1256cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1257cc53ce53SDavid Howells * other than its daemon the right to mount on its 1258cc53ce53SDavid Howells * superstructure. 1259cc53ce53SDavid Howells * 1260cc53ce53SDavid Howells * The filesystem may sleep at this point. 1261cc53ce53SDavid Howells */ 1262cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1263cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1264cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1265ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12661aed3e42SAl Viro path->dentry, false); 1267cc53ce53SDavid Howells if (ret < 0) 1268cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1269cc53ce53SDavid Howells } 1270cc53ce53SDavid Howells 1271cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1272cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1273cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1274cc53ce53SDavid Howells if (!mounted) 1275cc53ce53SDavid Howells break; 1276cc53ce53SDavid Howells dput(path->dentry); 1277cc53ce53SDavid Howells mntput(path->mnt); 1278cc53ce53SDavid Howells path->mnt = mounted; 1279cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1280cc53ce53SDavid Howells continue; 1281cc53ce53SDavid Howells } 1282cc53ce53SDavid Howells 1283cc53ce53SDavid Howells /* Don't handle automount points here */ 1284cc53ce53SDavid Howells break; 1285cc53ce53SDavid Howells } 1286cc53ce53SDavid Howells return 0; 1287cc53ce53SDavid Howells } 12884d359507SAl Viro EXPORT_SYMBOL(follow_down); 1289cc53ce53SDavid Howells 1290cc53ce53SDavid Howells /* 12919875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12929875cf80SDavid Howells */ 12939875cf80SDavid Howells static void follow_mount(struct path *path) 12949875cf80SDavid Howells { 12959875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12969875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12979875cf80SDavid Howells if (!mounted) 12989875cf80SDavid Howells break; 12999875cf80SDavid Howells dput(path->dentry); 13009875cf80SDavid Howells mntput(path->mnt); 13019875cf80SDavid Howells path->mnt = mounted; 13029875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13039875cf80SDavid Howells } 13049875cf80SDavid Howells } 13059875cf80SDavid Howells 130631e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 13071da177e4SLinus Torvalds { 13087bd88377SAl Viro if (!nd->root.mnt) 13092a737871SAl Viro set_root(nd); 1310e518ddb7SAndreas Mohr 13111da177e4SLinus Torvalds while(1) { 13124ac91378SJan Blunck struct dentry *old = nd->path.dentry; 13131da177e4SLinus Torvalds 13142a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 13152a737871SAl Viro nd->path.mnt == nd->root.mnt) { 13161da177e4SLinus Torvalds break; 13171da177e4SLinus Torvalds } 13184ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13193088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13203088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13211da177e4SLinus Torvalds dput(old); 13221da177e4SLinus Torvalds break; 13231da177e4SLinus Torvalds } 13243088dd70SAl Viro if (!follow_up(&nd->path)) 13251da177e4SLinus Torvalds break; 13261da177e4SLinus Torvalds } 132779ed0226SAl Viro follow_mount(&nd->path); 132831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13291da177e4SLinus Torvalds } 13301da177e4SLinus Torvalds 13311da177e4SLinus Torvalds /* 1332bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1333bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1334bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1335bad61189SMiklos Szeredi * 1336bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1337baa03890SNick Piggin */ 1338bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1339201f956eSAl Viro unsigned int flags, bool *need_lookup) 1340baa03890SNick Piggin { 1341baa03890SNick Piggin struct dentry *dentry; 1342bad61189SMiklos Szeredi int error; 1343baa03890SNick Piggin 1344bad61189SMiklos Szeredi *need_lookup = false; 1345bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1346bad61189SMiklos Szeredi if (dentry) { 134739e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1348201f956eSAl Viro error = d_revalidate(dentry, flags); 1349bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1350bad61189SMiklos Szeredi if (error < 0) { 1351bad61189SMiklos Szeredi dput(dentry); 1352bad61189SMiklos Szeredi return ERR_PTR(error); 13535542aa2fSEric W. Biederman } else { 13545542aa2fSEric W. Biederman d_invalidate(dentry); 1355bad61189SMiklos Szeredi dput(dentry); 1356bad61189SMiklos Szeredi dentry = NULL; 1357bad61189SMiklos Szeredi } 1358bad61189SMiklos Szeredi } 1359bad61189SMiklos Szeredi } 1360bad61189SMiklos Szeredi } 1361baa03890SNick Piggin 1362bad61189SMiklos Szeredi if (!dentry) { 1363bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1364baa03890SNick Piggin if (unlikely(!dentry)) 1365baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1366baa03890SNick Piggin 1367bad61189SMiklos Szeredi *need_lookup = true; 1368baa03890SNick Piggin } 1369baa03890SNick Piggin return dentry; 1370baa03890SNick Piggin } 1371baa03890SNick Piggin 1372baa03890SNick Piggin /* 137313a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 137413a2c3beSJ. Bruce Fields * unhashed. 1375bad61189SMiklos Szeredi * 1376bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 137744396f4bSJosef Bacik */ 1378bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 137972bd866aSAl Viro unsigned int flags) 138044396f4bSJosef Bacik { 138144396f4bSJosef Bacik struct dentry *old; 138244396f4bSJosef Bacik 138344396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1384bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1385e188dc02SMiklos Szeredi dput(dentry); 138644396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1387e188dc02SMiklos Szeredi } 138844396f4bSJosef Bacik 138972bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 139044396f4bSJosef Bacik if (unlikely(old)) { 139144396f4bSJosef Bacik dput(dentry); 139244396f4bSJosef Bacik dentry = old; 139344396f4bSJosef Bacik } 139444396f4bSJosef Bacik return dentry; 139544396f4bSJosef Bacik } 139644396f4bSJosef Bacik 1397a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 139872bd866aSAl Viro struct dentry *base, unsigned int flags) 1399a3255546SAl Viro { 1400bad61189SMiklos Szeredi bool need_lookup; 1401a3255546SAl Viro struct dentry *dentry; 1402a3255546SAl Viro 140372bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1404bad61189SMiklos Szeredi if (!need_lookup) 1405a3255546SAl Viro return dentry; 1406bad61189SMiklos Szeredi 140772bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1408a3255546SAl Viro } 1409a3255546SAl Viro 141044396f4bSJosef Bacik /* 14111da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 14121da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 14131da177e4SLinus Torvalds * It _is_ time-critical. 14141da177e4SLinus Torvalds */ 1415e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 141631e6b01fSNick Piggin struct path *path, struct inode **inode) 14171da177e4SLinus Torvalds { 14184ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 141931e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14205a18fff2SAl Viro int need_reval = 1; 14215a18fff2SAl Viro int status = 1; 14229875cf80SDavid Howells int err; 14239875cf80SDavid Howells 14243cac260aSAl Viro /* 1425b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1426b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1427b04f784eSNick Piggin * do the non-racy lookup, below. 1428b04f784eSNick Piggin */ 142931e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 143031e6b01fSNick Piggin unsigned seq; 1431766c4cbfSAl Viro bool negative; 1432da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14335a18fff2SAl Viro if (!dentry) 14345a18fff2SAl Viro goto unlazy; 14355a18fff2SAl Viro 143612f8ad4bSLinus Torvalds /* 143712f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 143812f8ad4bSLinus Torvalds * the dentry name information from lookup. 143912f8ad4bSLinus Torvalds */ 144012f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1441766c4cbfSAl Viro negative = d_is_negative(dentry); 144212f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 144312f8ad4bSLinus Torvalds return -ECHILD; 1444766c4cbfSAl Viro if (negative) 1445766c4cbfSAl Viro return -ENOENT; 144612f8ad4bSLinus Torvalds 144712f8ad4bSLinus Torvalds /* 144812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 144912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 145012f8ad4bSLinus Torvalds * 145112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 145212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 145312f8ad4bSLinus Torvalds */ 145431e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 145531e6b01fSNick Piggin return -ECHILD; 145631e6b01fSNick Piggin nd->seq = seq; 14575a18fff2SAl Viro 145824643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14594ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14605a18fff2SAl Viro if (unlikely(status <= 0)) { 14615a18fff2SAl Viro if (status != -ECHILD) 14625a18fff2SAl Viro need_reval = 0; 14635a18fff2SAl Viro goto unlazy; 14645a18fff2SAl Viro } 146524643087SAl Viro } 146631e6b01fSNick Piggin path->mnt = mnt; 146731e6b01fSNick Piggin path->dentry = dentry; 1468b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14699875cf80SDavid Howells return 0; 14705a18fff2SAl Viro unlazy: 147119660af7SAl Viro if (unlazy_walk(nd, dentry)) 14725a18fff2SAl Viro return -ECHILD; 14735a18fff2SAl Viro } else { 1474e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 147524643087SAl Viro } 14765a18fff2SAl Viro 147781e6f520SAl Viro if (unlikely(!dentry)) 147881e6f520SAl Viro goto need_lookup; 14795a18fff2SAl Viro 14805a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14814ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14825a18fff2SAl Viro if (unlikely(status <= 0)) { 14835a18fff2SAl Viro if (status < 0) { 14845a18fff2SAl Viro dput(dentry); 14855a18fff2SAl Viro return status; 14865a18fff2SAl Viro } 14875542aa2fSEric W. Biederman d_invalidate(dentry); 14885a18fff2SAl Viro dput(dentry); 148981e6f520SAl Viro goto need_lookup; 14905a18fff2SAl Viro } 1491697f514dSMiklos Szeredi 1492766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1493766c4cbfSAl Viro dput(dentry); 1494766c4cbfSAl Viro return -ENOENT; 1495766c4cbfSAl Viro } 14961da177e4SLinus Torvalds path->mnt = mnt; 14971da177e4SLinus Torvalds path->dentry = dentry; 14989875cf80SDavid Howells err = follow_managed(path, nd->flags); 149989312214SIan Kent if (unlikely(err < 0)) { 150089312214SIan Kent path_put_conditional(path, nd); 15019875cf80SDavid Howells return err; 150289312214SIan Kent } 1503a3fbbde7SAl Viro if (err) 1504a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 150531e6b01fSNick Piggin *inode = path->dentry->d_inode; 15061da177e4SLinus Torvalds return 0; 150781e6f520SAl Viro 150881e6f520SAl Viro need_lookup: 1509697f514dSMiklos Szeredi return 1; 1510697f514dSMiklos Szeredi } 1511697f514dSMiklos Szeredi 1512697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1513cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1514697f514dSMiklos Szeredi { 1515697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1516697f514dSMiklos Szeredi int err; 1517697f514dSMiklos Szeredi 1518697f514dSMiklos Szeredi parent = nd->path.dentry; 151981e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 152081e6f520SAl Viro 152181e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1522cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 152381e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 152481e6f520SAl Viro if (IS_ERR(dentry)) 152581e6f520SAl Viro return PTR_ERR(dentry); 1526697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1527697f514dSMiklos Szeredi path->dentry = dentry; 1528697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1529697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1530697f514dSMiklos Szeredi path_put_conditional(path, nd); 1531697f514dSMiklos Szeredi return err; 1532697f514dSMiklos Szeredi } 1533697f514dSMiklos Szeredi if (err) 1534697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1535697f514dSMiklos Szeredi return 0; 15361da177e4SLinus Torvalds } 15371da177e4SLinus Torvalds 153852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 153952094c8aSAl Viro { 154052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15414ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 154252094c8aSAl Viro if (err != -ECHILD) 154352094c8aSAl Viro return err; 154419660af7SAl Viro if (unlazy_walk(nd, NULL)) 154552094c8aSAl Viro return -ECHILD; 154652094c8aSAl Viro } 15474ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 154852094c8aSAl Viro } 154952094c8aSAl Viro 15509856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15519856fa1bSAl Viro { 15529856fa1bSAl Viro if (type == LAST_DOTDOT) { 15539856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15549856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15559856fa1bSAl Viro return -ECHILD; 15569856fa1bSAl Viro } else 15579856fa1bSAl Viro follow_dotdot(nd); 15589856fa1bSAl Viro } 15599856fa1bSAl Viro return 0; 15609856fa1bSAl Viro } 15619856fa1bSAl Viro 1562951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1563951361f9SAl Viro { 1564951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1565951361f9SAl Viro path_put(&nd->path); 1566951361f9SAl Viro } else { 1567951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15685b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1569951361f9SAl Viro nd->root.mnt = NULL; 15708b61e74fSAl Viro rcu_read_unlock(); 1571951361f9SAl Viro } 1572951361f9SAl Viro } 1573951361f9SAl Viro 15743ddcd056SLinus Torvalds /* 15753ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15763ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15773ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15783ddcd056SLinus Torvalds * for the common case. 15793ddcd056SLinus Torvalds */ 1580b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15813ddcd056SLinus Torvalds { 1582b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15833ddcd056SLinus Torvalds } 15843ddcd056SLinus Torvalds 1585caa85634SAl Viro static int walk_component(struct nameidata *nd, int follow) 1586ce57dfc1SAl Viro { 1587caa85634SAl Viro struct path path; 1588ce57dfc1SAl Viro struct inode *inode; 1589ce57dfc1SAl Viro int err; 1590ce57dfc1SAl Viro /* 1591ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1592ce57dfc1SAl Viro * to be able to know about the current root directory and 1593ce57dfc1SAl Viro * parent relationships. 1594ce57dfc1SAl Viro */ 159521b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 159621b9b073SAl Viro return handle_dots(nd, nd->last_type); 1597caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1598ce57dfc1SAl Viro if (unlikely(err)) { 1599697f514dSMiklos Szeredi if (err < 0) 1600697f514dSMiklos Szeredi goto out_err; 1601697f514dSMiklos Szeredi 1602caa85634SAl Viro err = lookup_slow(nd, &path); 1603697f514dSMiklos Szeredi if (err < 0) 1604697f514dSMiklos Szeredi goto out_err; 1605697f514dSMiklos Szeredi 1606caa85634SAl Viro inode = path.dentry->d_inode; 1607697f514dSMiklos Szeredi err = -ENOENT; 1608caa85634SAl Viro if (d_is_negative(path.dentry)) 1609697f514dSMiklos Szeredi goto out_path_put; 1610766c4cbfSAl Viro } 1611697f514dSMiklos Szeredi 1612caa85634SAl Viro if (should_follow_link(path.dentry, follow)) { 161319660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 1614caa85634SAl Viro if (unlikely(nd->path.mnt != path.mnt || 1615caa85634SAl Viro unlazy_walk(nd, path.dentry))) { 1616697f514dSMiklos Szeredi err = -ECHILD; 1617697f514dSMiklos Szeredi goto out_err; 161819660af7SAl Viro } 161919660af7SAl Viro } 1620caa85634SAl Viro BUG_ON(inode != path.dentry->d_inode); 1621caa85634SAl Viro nd->link = path; 1622ce57dfc1SAl Viro return 1; 1623ce57dfc1SAl Viro } 1624caa85634SAl Viro path_to_nameidata(&path, nd); 1625ce57dfc1SAl Viro nd->inode = inode; 1626ce57dfc1SAl Viro return 0; 1627697f514dSMiklos Szeredi 1628697f514dSMiklos Szeredi out_path_put: 1629caa85634SAl Viro path_to_nameidata(&path, nd); 1630697f514dSMiklos Szeredi out_err: 1631697f514dSMiklos Szeredi terminate_walk(nd); 1632697f514dSMiklos Szeredi return err; 1633ce57dfc1SAl Viro } 1634ce57dfc1SAl Viro 16351da177e4SLinus Torvalds /* 1636bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1637bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1638bfcfaa77SLinus Torvalds * 1639bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1640bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1641bfcfaa77SLinus Torvalds * fast. 1642bfcfaa77SLinus Torvalds * 1643bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1644bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1645bfcfaa77SLinus Torvalds * crossing operation. 1646bfcfaa77SLinus Torvalds * 1647bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1648bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1649bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1650bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1651bfcfaa77SLinus Torvalds */ 1652bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1653bfcfaa77SLinus Torvalds 1654f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1655bfcfaa77SLinus Torvalds 1656f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1657bfcfaa77SLinus Torvalds 1658bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1659bfcfaa77SLinus Torvalds { 166099d263d4SLinus Torvalds return hash_64(hash, 32); 1661bfcfaa77SLinus Torvalds } 1662bfcfaa77SLinus Torvalds 1663bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1664bfcfaa77SLinus Torvalds 1665bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1666bfcfaa77SLinus Torvalds 1667bfcfaa77SLinus Torvalds #endif 1668bfcfaa77SLinus Torvalds 1669bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1670bfcfaa77SLinus Torvalds { 1671bfcfaa77SLinus Torvalds unsigned long a, mask; 1672bfcfaa77SLinus Torvalds unsigned long hash = 0; 1673bfcfaa77SLinus Torvalds 1674bfcfaa77SLinus Torvalds for (;;) { 1675e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1676bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1677bfcfaa77SLinus Torvalds break; 1678bfcfaa77SLinus Torvalds hash += a; 1679f132c5beSAl Viro hash *= 9; 1680bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1681bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1682bfcfaa77SLinus Torvalds if (!len) 1683bfcfaa77SLinus Torvalds goto done; 1684bfcfaa77SLinus Torvalds } 1685a5c21dceSWill Deacon mask = bytemask_from_count(len); 1686bfcfaa77SLinus Torvalds hash += mask & a; 1687bfcfaa77SLinus Torvalds done: 1688bfcfaa77SLinus Torvalds return fold_hash(hash); 1689bfcfaa77SLinus Torvalds } 1690bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1691bfcfaa77SLinus Torvalds 1692bfcfaa77SLinus Torvalds /* 1693bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1694d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1695bfcfaa77SLinus Torvalds */ 1696d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1697bfcfaa77SLinus Torvalds { 169836126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 169936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1700bfcfaa77SLinus Torvalds 1701bfcfaa77SLinus Torvalds hash = a = 0; 1702bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1703bfcfaa77SLinus Torvalds do { 1704bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1705bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1706e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 170736126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 170836126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1709bfcfaa77SLinus Torvalds 171036126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 171136126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 171236126f8fSLinus Torvalds 171336126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 171436126f8fSLinus Torvalds 171536126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 17169226b5b4SLinus Torvalds len += find_zero(mask); 1717d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1718bfcfaa77SLinus Torvalds } 1719bfcfaa77SLinus Torvalds 1720bfcfaa77SLinus Torvalds #else 1721bfcfaa77SLinus Torvalds 17220145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 17230145acc2SLinus Torvalds { 17240145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 17250145acc2SLinus Torvalds while (len--) 17260145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 17270145acc2SLinus Torvalds return end_name_hash(hash); 17280145acc2SLinus Torvalds } 1729ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 17300145acc2SLinus Torvalds 17313ddcd056SLinus Torvalds /* 1732200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1733200e9ef7SLinus Torvalds * one character. 1734200e9ef7SLinus Torvalds */ 1735d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1736200e9ef7SLinus Torvalds { 1737200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1738200e9ef7SLinus Torvalds unsigned long len = 0, c; 1739200e9ef7SLinus Torvalds 1740200e9ef7SLinus Torvalds c = (unsigned char)*name; 1741200e9ef7SLinus Torvalds do { 1742200e9ef7SLinus Torvalds len++; 1743200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1744200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1745200e9ef7SLinus Torvalds } while (c && c != '/'); 1746d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1747200e9ef7SLinus Torvalds } 1748200e9ef7SLinus Torvalds 1749bfcfaa77SLinus Torvalds #endif 1750bfcfaa77SLinus Torvalds 1751200e9ef7SLinus Torvalds /* 17521da177e4SLinus Torvalds * Name resolution. 1753ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1754ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17551da177e4SLinus Torvalds * 1756ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1757ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17581da177e4SLinus Torvalds */ 17596de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17601da177e4SLinus Torvalds { 17611da177e4SLinus Torvalds int err; 17621da177e4SLinus Torvalds 17631da177e4SLinus Torvalds while (*name=='/') 17641da177e4SLinus Torvalds name++; 17651da177e4SLinus Torvalds if (!*name) 17669e18f10aSAl Viro return 0; 17671da177e4SLinus Torvalds 17681da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17691da177e4SLinus Torvalds for(;;) { 1770d6bb3e90SLinus Torvalds u64 hash_len; 1771fe479a58SAl Viro int type; 17721da177e4SLinus Torvalds 177352094c8aSAl Viro err = may_lookup(nd); 17741da177e4SLinus Torvalds if (err) 17751da177e4SLinus Torvalds break; 17761da177e4SLinus Torvalds 1777d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17781da177e4SLinus Torvalds 1779fe479a58SAl Viro type = LAST_NORM; 1780d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1781fe479a58SAl Viro case 2: 1782200e9ef7SLinus Torvalds if (name[1] == '.') { 1783fe479a58SAl Viro type = LAST_DOTDOT; 178416c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 178516c2cd71SAl Viro } 1786fe479a58SAl Viro break; 1787fe479a58SAl Viro case 1: 1788fe479a58SAl Viro type = LAST_DOT; 1789fe479a58SAl Viro } 17905a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17915a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 179216c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17935a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1794a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1795da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 17965a202bcdSAl Viro if (err < 0) 17975a202bcdSAl Viro break; 1798d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1799d6bb3e90SLinus Torvalds name = this.name; 18005a202bcdSAl Viro } 18015a202bcdSAl Viro } 1802fe479a58SAl Viro 1803d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1804d6bb3e90SLinus Torvalds nd->last.name = name; 18055f4a6a69SAl Viro nd->last_type = type; 18065f4a6a69SAl Viro 1807d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1808d6bb3e90SLinus Torvalds if (!*name) 1809bdf6cbf1SAl Viro goto OK; 1810200e9ef7SLinus Torvalds /* 1811200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1812200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1813200e9ef7SLinus Torvalds */ 1814200e9ef7SLinus Torvalds do { 1815d6bb3e90SLinus Torvalds name++; 1816d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1817d6bb3e90SLinus Torvalds if (!*name) 1818bdf6cbf1SAl Viro goto OK; 18195f4a6a69SAl Viro 1820caa85634SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 1821bb8603f8SAl Viro Walked: 1822ce57dfc1SAl Viro if (err < 0) 1823bdf6cbf1SAl Viro goto Err; 1824fe479a58SAl Viro 1825ce57dfc1SAl Viro if (err) { 1826d40bcc09SAl Viro const char *s; 1827d40bcc09SAl Viro 1828894bc8c4SAl Viro err = nd_alloc_stack(nd); 1829894bc8c4SAl Viro if (unlikely(err)) { 1830894bc8c4SAl Viro path_to_nameidata(&nd->link, nd); 1831894bc8c4SAl Viro break; 18325a460275SAl Viro } 18335a460275SAl Viro 18343b2e7f75SAl Viro s = get_link(nd); 18355a460275SAl Viro 1836172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1837172a39a0SAl Viro err = PTR_ERR(s); 1838bdf6cbf1SAl Viro goto Err; 1839172a39a0SAl Viro } 1840172a39a0SAl Viro err = 0; 184112b09578SAl Viro if (unlikely(!s)) { 184212b09578SAl Viro /* jumped */ 1843b9ff4429SAl Viro put_link(nd); 184412b09578SAl Viro } else { 1845172a39a0SAl Viro if (*s == '/') { 1846172a39a0SAl Viro if (!nd->root.mnt) 1847172a39a0SAl Viro set_root(nd); 1848172a39a0SAl Viro path_put(&nd->path); 1849172a39a0SAl Viro nd->path = nd->root; 1850172a39a0SAl Viro path_get(&nd->root); 1851172a39a0SAl Viro nd->flags |= LOOKUP_JUMPED; 18529e18f10aSAl Viro while (unlikely(*++s == '/')) 18539e18f10aSAl Viro ; 1854172a39a0SAl Viro } 1855172a39a0SAl Viro nd->inode = nd->path.dentry->d_inode; 1856071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 18579e18f10aSAl Viro if (!*s) 18589e18f10aSAl Viro goto OK; 185932cd7468SAl Viro name = s; 18609e18f10aSAl Viro continue; 186148c8b0c5SAl Viro } 186231e6b01fSNick Piggin } 186344b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18643ddcd056SLinus Torvalds err = -ENOTDIR; 18653ddcd056SLinus Torvalds break; 18665f4a6a69SAl Viro } 1867ce57dfc1SAl Viro } 1868951361f9SAl Viro terminate_walk(nd); 1869bdf6cbf1SAl Viro Err: 187021c3003dSAl Viro while (unlikely(nd->depth > 1)) 1871b9ff4429SAl Viro put_link(nd); 18721da177e4SLinus Torvalds return err; 1873bdf6cbf1SAl Viro OK: 1874071bf501SAl Viro if (unlikely(nd->depth > 1)) { 1875071bf501SAl Viro name = nd->stack[nd->depth - 1].name; 187607681481SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 1877b9ff4429SAl Viro put_link(nd); 187807681481SAl Viro goto Walked; 187907681481SAl Viro } 1880bdf6cbf1SAl Viro return 0; 18811da177e4SLinus Torvalds } 18821da177e4SLinus Torvalds 18836e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18845e53084dSAl Viro struct nameidata *nd) 188531e6b01fSNick Piggin { 188631e6b01fSNick Piggin int retval = 0; 1887fd2f7cb5SAl Viro const char *s = name->name; 188831e6b01fSNick Piggin 188931e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1890980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 189131e6b01fSNick Piggin nd->depth = 0; 18925e53084dSAl Viro nd->base = NULL; 18935b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1894b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1895b18825a7SDavid Howells struct inode *inode = root->d_inode; 1896fd2f7cb5SAl Viro if (*s) { 189744b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18985b6ca027SAl Viro return -ENOTDIR; 18995b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 19005b6ca027SAl Viro if (retval) 19015b6ca027SAl Viro return retval; 190273d049a4SAl Viro } 19035b6ca027SAl Viro nd->path = nd->root; 19045b6ca027SAl Viro nd->inode = inode; 19055b6ca027SAl Viro if (flags & LOOKUP_RCU) { 19068b61e74fSAl Viro rcu_read_lock(); 19075b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 190848a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 19095b6ca027SAl Viro } else { 19105b6ca027SAl Viro path_get(&nd->path); 19115b6ca027SAl Viro } 1912d465887fSAl Viro goto done; 19135b6ca027SAl Viro } 19145b6ca027SAl Viro 191531e6b01fSNick Piggin nd->root.mnt = NULL; 191631e6b01fSNick Piggin 191748a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1918fd2f7cb5SAl Viro if (*s == '/') { 1919e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19208b61e74fSAl Viro rcu_read_lock(); 19217bd88377SAl Viro nd->seq = set_root_rcu(nd); 1922e41f7d4eSAl Viro } else { 1923e41f7d4eSAl Viro set_root(nd); 1924e41f7d4eSAl Viro path_get(&nd->root); 1925e41f7d4eSAl Viro } 192631e6b01fSNick Piggin nd->path = nd->root; 192731e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1928e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 192931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1930c28cc364SNick Piggin unsigned seq; 193131e6b01fSNick Piggin 19328b61e74fSAl Viro rcu_read_lock(); 193331e6b01fSNick Piggin 1934c28cc364SNick Piggin do { 1935c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 193631e6b01fSNick Piggin nd->path = fs->pwd; 1937c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1938c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1939e41f7d4eSAl Viro } else { 1940e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1941e41f7d4eSAl Viro } 194231e6b01fSNick Piggin } else { 1943582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19442903ff01SAl Viro struct fd f = fdget_raw(dfd); 194531e6b01fSNick Piggin struct dentry *dentry; 194631e6b01fSNick Piggin 19472903ff01SAl Viro if (!f.file) 19482903ff01SAl Viro return -EBADF; 194931e6b01fSNick Piggin 19502903ff01SAl Viro dentry = f.file->f_path.dentry; 195131e6b01fSNick Piggin 1952fd2f7cb5SAl Viro if (*s) { 195344b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19542903ff01SAl Viro fdput(f); 19552903ff01SAl Viro return -ENOTDIR; 1956f52e0c11SAl Viro } 19572903ff01SAl Viro } 19582903ff01SAl Viro 19592903ff01SAl Viro nd->path = f.file->f_path; 1960e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19619c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19625e53084dSAl Viro nd->base = f.file; 1963c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19648b61e74fSAl Viro rcu_read_lock(); 19655590ff0dSUlrich Drepper } else { 19662903ff01SAl Viro path_get(&nd->path); 19672903ff01SAl Viro fdput(f); 19681da177e4SLinus Torvalds } 1969e41f7d4eSAl Viro } 1970e41f7d4eSAl Viro 197131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19724023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1973d465887fSAl Viro goto done; 19744023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1975d465887fSAl Viro goto done; 19764023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19774023bfc9SAl Viro nd->root.mnt = NULL; 19784023bfc9SAl Viro rcu_read_unlock(); 19794023bfc9SAl Viro return -ECHILD; 1980d465887fSAl Viro done: 1981d465887fSAl Viro current->total_link_count = 0; 1982ef1a3e7bSAl Viro nd->depth++; 1983ef1a3e7bSAl Viro retval = link_path_walk(s, nd); 1984ef1a3e7bSAl Viro nd->depth--; 1985ef1a3e7bSAl Viro return retval; 19869b4a9b14SAl Viro } 19879b4a9b14SAl Viro 1988893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1989893b7775SAl Viro { 1990893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1991893b7775SAl Viro path_put(&nd->root); 1992893b7775SAl Viro nd->root.mnt = NULL; 1993893b7775SAl Viro } 1994893b7775SAl Viro if (unlikely(nd->base)) 1995893b7775SAl Viro fput(nd->base); 19969b4a9b14SAl Viro } 19979b4a9b14SAl Viro 19981d8e03d3SAl Viro static int trailing_symlink(struct nameidata *nd) 199995fa25d9SAl Viro { 200095fa25d9SAl Viro const char *s; 20011d8e03d3SAl Viro int error = may_follow_link(&nd->link, nd); 200295fa25d9SAl Viro if (unlikely(error)) 200395fa25d9SAl Viro return error; 200495fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 20053b2e7f75SAl Viro s = get_link(nd); 200695fa25d9SAl Viro if (unlikely(IS_ERR(s))) 200795fa25d9SAl Viro return PTR_ERR(s); 20089ea57b72SAl Viro if (unlikely(!s)) 200995fa25d9SAl Viro return 0; 201095fa25d9SAl Viro if (*s == '/') { 201195fa25d9SAl Viro if (!nd->root.mnt) 201295fa25d9SAl Viro set_root(nd); 201395fa25d9SAl Viro path_put(&nd->path); 201495fa25d9SAl Viro nd->path = nd->root; 201595fa25d9SAl Viro path_get(&nd->root); 201695fa25d9SAl Viro nd->flags |= LOOKUP_JUMPED; 201795fa25d9SAl Viro } 201895fa25d9SAl Viro nd->inode = nd->path.dentry->d_inode; 201995fa25d9SAl Viro error = link_path_walk(s, nd); 202021c3003dSAl Viro if (unlikely(error)) 2021b9ff4429SAl Viro put_link(nd); 202295fa25d9SAl Viro return error; 202395fa25d9SAl Viro } 202495fa25d9SAl Viro 2025caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2026bd92d7feSAl Viro { 2027bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2028bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2029bd92d7feSAl Viro 2030bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2031caa85634SAl Viro return walk_component(nd, nd->flags & LOOKUP_FOLLOW); 2032bd92d7feSAl Viro } 2033bd92d7feSAl Viro 20349b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20355eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20369b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20379b4a9b14SAl Viro { 2038bd92d7feSAl Viro int err; 203931e6b01fSNick Piggin 204031e6b01fSNick Piggin /* 204131e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 204231e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 204331e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 204431e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 204531e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 204631e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 204731e6b01fSNick Piggin * analogue, foo_rcu(). 204831e6b01fSNick Piggin * 204931e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 205031e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 205131e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 205231e6b01fSNick Piggin * be able to complete). 205331e6b01fSNick Piggin */ 20546e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2055bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2056caa85634SAl Viro err = lookup_last(nd); 2057bd92d7feSAl Viro while (err > 0) { 20581d8e03d3SAl Viro err = trailing_symlink(nd); 20596d7b5aaeSAl Viro if (err) 20606d7b5aaeSAl Viro break; 2061caa85634SAl Viro err = lookup_last(nd); 2062b9ff4429SAl Viro put_link(nd); 2063bd92d7feSAl Viro } 2064bd92d7feSAl Viro } 2065ee0827cdSAl Viro 20669f1fafeeSAl Viro if (!err) 20679f1fafeeSAl Viro err = complete_walk(nd); 2068bd92d7feSAl Viro 2069bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 207044b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2071bd92d7feSAl Viro path_put(&nd->path); 2072bd23a539SAl Viro err = -ENOTDIR; 2073bd92d7feSAl Viro } 2074bd92d7feSAl Viro } 207516c2cd71SAl Viro 2076893b7775SAl Viro path_cleanup(nd); 2077bd92d7feSAl Viro return err; 207831e6b01fSNick Piggin } 207931e6b01fSNick Piggin 2080873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2081873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2082873f1eedSJeff Layton { 2083894bc8c4SAl Viro int retval; 2084894bc8c4SAl Viro 2085894bc8c4SAl Viro set_nameidata(nd); 2086894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2087894bc8c4SAl Viro 2088873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20895eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2090873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20915eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2092873f1eedSJeff Layton 2093873f1eedSJeff Layton if (likely(!retval)) 2094adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2095894bc8c4SAl Viro restore_nameidata(nd); 2096873f1eedSJeff Layton return retval; 2097873f1eedSJeff Layton } 2098873f1eedSJeff Layton 209979714f72SAl Viro /* does lookup, returns the object with parent locked */ 210079714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 21015590ff0dSUlrich Drepper { 210251689104SPaul Moore struct filename *filename = getname_kernel(name); 210379714f72SAl Viro struct nameidata nd; 210479714f72SAl Viro struct dentry *d; 210551689104SPaul Moore int err; 210651689104SPaul Moore 210751689104SPaul Moore if (IS_ERR(filename)) 210851689104SPaul Moore return ERR_CAST(filename); 210951689104SPaul Moore 211051689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 211151689104SPaul Moore if (err) { 211251689104SPaul Moore d = ERR_PTR(err); 211351689104SPaul Moore goto out; 211451689104SPaul Moore } 211579714f72SAl Viro if (nd.last_type != LAST_NORM) { 211679714f72SAl Viro path_put(&nd.path); 211751689104SPaul Moore d = ERR_PTR(-EINVAL); 211851689104SPaul Moore goto out; 211979714f72SAl Viro } 212079714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 21211e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 212279714f72SAl Viro if (IS_ERR(d)) { 212379714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 212479714f72SAl Viro path_put(&nd.path); 212551689104SPaul Moore goto out; 212679714f72SAl Viro } 212779714f72SAl Viro *path = nd.path; 212851689104SPaul Moore out: 212951689104SPaul Moore putname(filename); 213079714f72SAl Viro return d; 21315590ff0dSUlrich Drepper } 21325590ff0dSUlrich Drepper 2133d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2134d1811465SAl Viro { 2135d1811465SAl Viro struct nameidata nd; 213674eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 213774eb8cc5SAl Viro int res = PTR_ERR(filename); 213874eb8cc5SAl Viro 213974eb8cc5SAl Viro if (!IS_ERR(filename)) { 214074eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 214174eb8cc5SAl Viro putname(filename); 2142d1811465SAl Viro if (!res) 2143d1811465SAl Viro *path = nd.path; 214474eb8cc5SAl Viro } 2145d1811465SAl Viro return res; 2146d1811465SAl Viro } 21474d359507SAl Viro EXPORT_SYMBOL(kern_path); 2148d1811465SAl Viro 214916f18200SJosef 'Jeff' Sipek /** 215016f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 215116f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 215216f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 215316f18200SJosef 'Jeff' Sipek * @name: pointer to file name 215416f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2155e0a01249SAl Viro * @path: pointer to struct path to fill 215616f18200SJosef 'Jeff' Sipek */ 215716f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 215816f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2159e0a01249SAl Viro struct path *path) 216016f18200SJosef 'Jeff' Sipek { 216174eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 216274eb8cc5SAl Viro int err = PTR_ERR(filename); 216374eb8cc5SAl Viro 216474eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 216574eb8cc5SAl Viro 216674eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 216774eb8cc5SAl Viro if (!IS_ERR(filename)) { 2168e0a01249SAl Viro struct nameidata nd; 2169e0a01249SAl Viro nd.root.dentry = dentry; 2170e0a01249SAl Viro nd.root.mnt = mnt; 217174eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 217274eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2173e0a01249SAl Viro if (!err) 2174e0a01249SAl Viro *path = nd.path; 217574eb8cc5SAl Viro putname(filename); 217674eb8cc5SAl Viro } 2177e0a01249SAl Viro return err; 217816f18200SJosef 'Jeff' Sipek } 21794d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 218016f18200SJosef 'Jeff' Sipek 2181eead1911SChristoph Hellwig /** 2182a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2183eead1911SChristoph Hellwig * @name: pathname component to lookup 2184eead1911SChristoph Hellwig * @base: base directory to lookup from 2185eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2186eead1911SChristoph Hellwig * 2187a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21889e7543e9SAl Viro * not be called by generic code. 2189eead1911SChristoph Hellwig */ 2190057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2191057f6c01SJames Morris { 2192057f6c01SJames Morris struct qstr this; 21936a96ba54SAl Viro unsigned int c; 2194cda309deSMiklos Szeredi int err; 2195057f6c01SJames Morris 21962f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21972f9092e1SDavid Woodhouse 21986a96ba54SAl Viro this.name = name; 21996a96ba54SAl Viro this.len = len; 22000145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 22016a96ba54SAl Viro if (!len) 22026a96ba54SAl Viro return ERR_PTR(-EACCES); 22036a96ba54SAl Viro 220421d8a15aSAl Viro if (unlikely(name[0] == '.')) { 220521d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 220621d8a15aSAl Viro return ERR_PTR(-EACCES); 220721d8a15aSAl Viro } 220821d8a15aSAl Viro 22096a96ba54SAl Viro while (len--) { 22106a96ba54SAl Viro c = *(const unsigned char *)name++; 22116a96ba54SAl Viro if (c == '/' || c == '\0') 22126a96ba54SAl Viro return ERR_PTR(-EACCES); 22136a96ba54SAl Viro } 22145a202bcdSAl Viro /* 22155a202bcdSAl Viro * See if the low-level filesystem might want 22165a202bcdSAl Viro * to use its own hash.. 22175a202bcdSAl Viro */ 22185a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2219da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 22205a202bcdSAl Viro if (err < 0) 22215a202bcdSAl Viro return ERR_PTR(err); 22225a202bcdSAl Viro } 2223eead1911SChristoph Hellwig 2224cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2225cda309deSMiklos Szeredi if (err) 2226cda309deSMiklos Szeredi return ERR_PTR(err); 2227cda309deSMiklos Szeredi 222872bd866aSAl Viro return __lookup_hash(&this, base, 0); 2229057f6c01SJames Morris } 22304d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2231057f6c01SJames Morris 22321fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22331fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22341da177e4SLinus Torvalds { 22352d8f3038SAl Viro struct nameidata nd; 223691a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22371da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22381da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22392d8f3038SAl Viro 22402d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22412d8f3038SAl Viro 2242873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22431da177e4SLinus Torvalds putname(tmp); 22442d8f3038SAl Viro if (!err) 22452d8f3038SAl Viro *path = nd.path; 22461da177e4SLinus Torvalds } 22471da177e4SLinus Torvalds return err; 22481da177e4SLinus Torvalds } 22491da177e4SLinus Torvalds 22501fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22511fa1e7f6SAndy Whitcroft struct path *path) 22521fa1e7f6SAndy Whitcroft { 2253f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22541fa1e7f6SAndy Whitcroft } 22554d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22561fa1e7f6SAndy Whitcroft 2257873f1eedSJeff Layton /* 2258873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2259873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2260873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2261873f1eedSJeff Layton * path-walking is complete. 2262873f1eedSJeff Layton */ 226391a27b2aSJeff Layton static struct filename * 2264f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2265f5beed75SAl Viro struct path *parent, 2266f5beed75SAl Viro struct qstr *last, 2267f5beed75SAl Viro int *type, 22689e790bd6SJeff Layton unsigned int flags) 22692ad94ae6SAl Viro { 2270f5beed75SAl Viro struct nameidata nd; 227191a27b2aSJeff Layton struct filename *s = getname(path); 22722ad94ae6SAl Viro int error; 22732ad94ae6SAl Viro 22749e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22759e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22769e790bd6SJeff Layton 22772ad94ae6SAl Viro if (IS_ERR(s)) 227891a27b2aSJeff Layton return s; 22792ad94ae6SAl Viro 2280f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 228191a27b2aSJeff Layton if (error) { 22822ad94ae6SAl Viro putname(s); 228391a27b2aSJeff Layton return ERR_PTR(error); 228491a27b2aSJeff Layton } 2285f5beed75SAl Viro *parent = nd.path; 2286f5beed75SAl Viro *last = nd.last; 2287f5beed75SAl Viro *type = nd.last_type; 22882ad94ae6SAl Viro 228991a27b2aSJeff Layton return s; 22902ad94ae6SAl Viro } 22912ad94ae6SAl Viro 22928033426eSJeff Layton /** 2293197df04cSAl Viro * mountpoint_last - look up last component for umount 22948033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22958033426eSJeff Layton * @path: pointer to container for result 22968033426eSJeff Layton * 22978033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22988033426eSJeff Layton * need to resolve the path without doing any revalidation. 22998033426eSJeff Layton * 23008033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 23018033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 23028033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 23038033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 23048033426eSJeff Layton * bogus and it doesn't exist. 23058033426eSJeff Layton * 23068033426eSJeff Layton * Returns: 23078033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 23088033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 23098033426eSJeff Layton * put in this case. 23108033426eSJeff Layton * 23118033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 23128033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 23138033426eSJeff Layton * The nd->path reference will also be put. 23148033426eSJeff Layton * 23158033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 23168033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 23178033426eSJeff Layton * to the link, and nd->path will *not* be put. 23188033426eSJeff Layton */ 23198033426eSJeff Layton static int 2320197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 23218033426eSJeff Layton { 23228033426eSJeff Layton int error = 0; 23238033426eSJeff Layton struct dentry *dentry; 23248033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23258033426eSJeff Layton 232635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 232735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 232835759521SAl Viro if (unlazy_walk(nd, NULL)) { 23298033426eSJeff Layton error = -ECHILD; 233035759521SAl Viro goto out; 233135759521SAl Viro } 23328033426eSJeff Layton } 23338033426eSJeff Layton 23348033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23358033426eSJeff Layton 23368033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23378033426eSJeff Layton error = handle_dots(nd, nd->last_type); 233835759521SAl Viro if (error) 233935759521SAl Viro goto out; 23408033426eSJeff Layton dentry = dget(nd->path.dentry); 234135759521SAl Viro goto done; 23428033426eSJeff Layton } 23438033426eSJeff Layton 23448033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23458033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23468033426eSJeff Layton if (!dentry) { 23478033426eSJeff Layton /* 23488033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23498033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23508033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23518033426eSJeff Layton */ 23528033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23538033426eSJeff Layton if (!dentry) { 23548033426eSJeff Layton error = -ENOMEM; 2355bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 235635759521SAl Viro goto out; 23578033426eSJeff Layton } 235835759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 235935759521SAl Viro error = PTR_ERR(dentry); 2360bcceeebaSDave Jones if (IS_ERR(dentry)) { 2361bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 236235759521SAl Viro goto out; 23638033426eSJeff Layton } 2364bcceeebaSDave Jones } 23658033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23668033426eSJeff Layton 236735759521SAl Viro done: 2368698934dfSDavid Howells if (d_is_negative(dentry)) { 23698033426eSJeff Layton error = -ENOENT; 23708033426eSJeff Layton dput(dentry); 237135759521SAl Viro goto out; 237235759521SAl Viro } 23738033426eSJeff Layton path->dentry = dentry; 2374295dc39dSVasily Averin path->mnt = nd->path.mnt; 2375caa85634SAl Viro if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) { 2376caa85634SAl Viro nd->link = *path; 23778033426eSJeff Layton return 1; 2378caa85634SAl Viro } 2379295dc39dSVasily Averin mntget(path->mnt); 23808033426eSJeff Layton follow_mount(path); 238135759521SAl Viro error = 0; 238235759521SAl Viro out: 23838033426eSJeff Layton terminate_walk(nd); 23848033426eSJeff Layton return error; 23858033426eSJeff Layton } 23868033426eSJeff Layton 23878033426eSJeff Layton /** 2388197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23898033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23908033426eSJeff Layton * @name: full pathname to walk 2391606d6fe3SRandy Dunlap * @path: pointer to container for result 23928033426eSJeff Layton * @flags: lookup flags 23938033426eSJeff Layton * 23948033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2395606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23968033426eSJeff Layton */ 23978033426eSJeff Layton static int 2398668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 239946afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 24008033426eSJeff Layton { 240146afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 24028033426eSJeff Layton if (unlikely(err)) 2403115cbfdcSAl Viro goto out; 24048033426eSJeff Layton 240546afd6f6SAl Viro err = mountpoint_last(nd, path); 24068033426eSJeff Layton while (err > 0) { 24071d8e03d3SAl Viro err = trailing_symlink(nd); 24088033426eSJeff Layton if (err) 24098033426eSJeff Layton break; 241046afd6f6SAl Viro err = mountpoint_last(nd, path); 2411b9ff4429SAl Viro put_link(nd); 24128033426eSJeff Layton } 24138033426eSJeff Layton out: 241446afd6f6SAl Viro path_cleanup(nd); 24158033426eSJeff Layton return err; 24168033426eSJeff Layton } 24178033426eSJeff Layton 24182d864651SAl Viro static int 2419668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 24202d864651SAl Viro unsigned int flags) 24212d864651SAl Viro { 242246afd6f6SAl Viro struct nameidata nd; 2423cbaab2dbSAl Viro int error; 2424668696dcSAl Viro if (IS_ERR(name)) 2425668696dcSAl Viro return PTR_ERR(name); 2426894bc8c4SAl Viro set_nameidata(&nd); 242746afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24282d864651SAl Viro if (unlikely(error == -ECHILD)) 242946afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24302d864651SAl Viro if (unlikely(error == -ESTALE)) 243146afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24322d864651SAl Viro if (likely(!error)) 2433668696dcSAl Viro audit_inode(name, path->dentry, 0); 2434894bc8c4SAl Viro restore_nameidata(&nd); 2435668696dcSAl Viro putname(name); 24362d864651SAl Viro return error; 24372d864651SAl Viro } 24382d864651SAl Viro 24398033426eSJeff Layton /** 2440197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24418033426eSJeff Layton * @dfd: directory file descriptor 24428033426eSJeff Layton * @name: pathname from userland 24438033426eSJeff Layton * @flags: lookup flags 24448033426eSJeff Layton * @path: pointer to container to hold result 24458033426eSJeff Layton * 24468033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24478033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24488033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24498033426eSJeff Layton * and avoid revalidating the last component. 24508033426eSJeff Layton * 24518033426eSJeff Layton * Returns 0 and populates "path" on success. 24528033426eSJeff Layton */ 24538033426eSJeff Layton int 2454197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24558033426eSJeff Layton struct path *path) 24568033426eSJeff Layton { 2457cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24588033426eSJeff Layton } 24598033426eSJeff Layton 24602d864651SAl Viro int 24612d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24622d864651SAl Viro unsigned int flags) 24632d864651SAl Viro { 2464cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24652d864651SAl Viro } 24662d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24672d864651SAl Viro 2468cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24691da177e4SLinus Torvalds { 24708e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2471da9592edSDavid Howells 24728e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24731da177e4SLinus Torvalds return 0; 24748e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24751da177e4SLinus Torvalds return 0; 247623adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24771da177e4SLinus Torvalds } 2478cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24791da177e4SLinus Torvalds 24801da177e4SLinus Torvalds /* 24811da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24821da177e4SLinus Torvalds * whether the type of victim is right. 24831da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24841da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24851da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24861da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24871da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24881da177e4SLinus Torvalds * a. be owner of dir, or 24891da177e4SLinus Torvalds * b. be owner of victim, or 24901da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24911da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24921da177e4SLinus Torvalds * links pointing to it. 24931da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24941da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24951da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24961da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24971da177e4SLinus Torvalds * nfs_async_unlink(). 24981da177e4SLinus Torvalds */ 2499b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 25001da177e4SLinus Torvalds { 2501b18825a7SDavid Howells struct inode *inode = victim->d_inode; 25021da177e4SLinus Torvalds int error; 25031da177e4SLinus Torvalds 2504b18825a7SDavid Howells if (d_is_negative(victim)) 25051da177e4SLinus Torvalds return -ENOENT; 2506b18825a7SDavid Howells BUG_ON(!inode); 25071da177e4SLinus Torvalds 25081da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 25094fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 25101da177e4SLinus Torvalds 2511f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 25121da177e4SLinus Torvalds if (error) 25131da177e4SLinus Torvalds return error; 25141da177e4SLinus Torvalds if (IS_APPEND(dir)) 25151da177e4SLinus Torvalds return -EPERM; 2516b18825a7SDavid Howells 2517b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2518b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 25191da177e4SLinus Torvalds return -EPERM; 25201da177e4SLinus Torvalds if (isdir) { 252144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 25221da177e4SLinus Torvalds return -ENOTDIR; 25231da177e4SLinus Torvalds if (IS_ROOT(victim)) 25241da177e4SLinus Torvalds return -EBUSY; 252544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 25261da177e4SLinus Torvalds return -EISDIR; 25271da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25281da177e4SLinus Torvalds return -ENOENT; 25291da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25301da177e4SLinus Torvalds return -EBUSY; 25311da177e4SLinus Torvalds return 0; 25321da177e4SLinus Torvalds } 25331da177e4SLinus Torvalds 25341da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25351da177e4SLinus Torvalds * dir. 25361da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25371da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25381da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25391da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25401da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25411da177e4SLinus Torvalds */ 2542a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25431da177e4SLinus Torvalds { 254414e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25451da177e4SLinus Torvalds if (child->d_inode) 25461da177e4SLinus Torvalds return -EEXIST; 25471da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25481da177e4SLinus Torvalds return -ENOENT; 2549f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25501da177e4SLinus Torvalds } 25511da177e4SLinus Torvalds 25521da177e4SLinus Torvalds /* 25531da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25541da177e4SLinus Torvalds */ 25551da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25561da177e4SLinus Torvalds { 25571da177e4SLinus Torvalds struct dentry *p; 25581da177e4SLinus Torvalds 25591da177e4SLinus Torvalds if (p1 == p2) { 2560f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25611da177e4SLinus Torvalds return NULL; 25621da177e4SLinus Torvalds } 25631da177e4SLinus Torvalds 2564a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25651da177e4SLinus Torvalds 2566e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2567e2761a11SOGAWA Hirofumi if (p) { 2568f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2569f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25701da177e4SLinus Torvalds return p; 25711da177e4SLinus Torvalds } 25721da177e4SLinus Torvalds 2573e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2574e2761a11SOGAWA Hirofumi if (p) { 2575f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2576f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25771da177e4SLinus Torvalds return p; 25781da177e4SLinus Torvalds } 25791da177e4SLinus Torvalds 2580f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2581d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25821da177e4SLinus Torvalds return NULL; 25831da177e4SLinus Torvalds } 25844d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25851da177e4SLinus Torvalds 25861da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25871da177e4SLinus Torvalds { 25881b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25891da177e4SLinus Torvalds if (p1 != p2) { 25901b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2591a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25921da177e4SLinus Torvalds } 25931da177e4SLinus Torvalds } 25944d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25951da177e4SLinus Torvalds 25964acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2597312b63fbSAl Viro bool want_excl) 25981da177e4SLinus Torvalds { 2599a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 26001da177e4SLinus Torvalds if (error) 26011da177e4SLinus Torvalds return error; 26021da177e4SLinus Torvalds 2603acfa4380SAl Viro if (!dir->i_op->create) 26041da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 26051da177e4SLinus Torvalds mode &= S_IALLUGO; 26061da177e4SLinus Torvalds mode |= S_IFREG; 26071da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 26081da177e4SLinus Torvalds if (error) 26091da177e4SLinus Torvalds return error; 2610312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2611a74574aaSStephen Smalley if (!error) 2612f38aa942SAmy Griffis fsnotify_create(dir, dentry); 26131da177e4SLinus Torvalds return error; 26141da177e4SLinus Torvalds } 26154d359507SAl Viro EXPORT_SYMBOL(vfs_create); 26161da177e4SLinus Torvalds 261773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 26181da177e4SLinus Torvalds { 26193fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 26201da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 26211da177e4SLinus Torvalds int error; 26221da177e4SLinus Torvalds 2623bcda7652SAl Viro /* O_PATH? */ 2624bcda7652SAl Viro if (!acc_mode) 2625bcda7652SAl Viro return 0; 2626bcda7652SAl Viro 26271da177e4SLinus Torvalds if (!inode) 26281da177e4SLinus Torvalds return -ENOENT; 26291da177e4SLinus Torvalds 2630c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2631c8fe8f30SChristoph Hellwig case S_IFLNK: 26321da177e4SLinus Torvalds return -ELOOP; 2633c8fe8f30SChristoph Hellwig case S_IFDIR: 2634c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26351da177e4SLinus Torvalds return -EISDIR; 2636c8fe8f30SChristoph Hellwig break; 2637c8fe8f30SChristoph Hellwig case S_IFBLK: 2638c8fe8f30SChristoph Hellwig case S_IFCHR: 26393fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26401da177e4SLinus Torvalds return -EACCES; 2641c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2642c8fe8f30SChristoph Hellwig case S_IFIFO: 2643c8fe8f30SChristoph Hellwig case S_IFSOCK: 26441da177e4SLinus Torvalds flag &= ~O_TRUNC; 2645c8fe8f30SChristoph Hellwig break; 26464a3fd211SDave Hansen } 2647b41572e9SDave Hansen 26483fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2649b41572e9SDave Hansen if (error) 2650b41572e9SDave Hansen return error; 26516146f0d5SMimi Zohar 26521da177e4SLinus Torvalds /* 26531da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26541da177e4SLinus Torvalds */ 26551da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26568737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26577715b521SAl Viro return -EPERM; 26581da177e4SLinus Torvalds if (flag & O_TRUNC) 26597715b521SAl Viro return -EPERM; 26601da177e4SLinus Torvalds } 26611da177e4SLinus Torvalds 26621da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26632e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26647715b521SAl Viro return -EPERM; 26651da177e4SLinus Torvalds 2666f3c7691eSJ. Bruce Fields return 0; 26677715b521SAl Viro } 26687715b521SAl Viro 2669e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26707715b521SAl Viro { 2671e1181ee6SJeff Layton struct path *path = &filp->f_path; 26727715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26737715b521SAl Viro int error = get_write_access(inode); 26741da177e4SLinus Torvalds if (error) 26757715b521SAl Viro return error; 26761da177e4SLinus Torvalds /* 26771da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26781da177e4SLinus Torvalds */ 2679d7a06983SJeff Layton error = locks_verify_locked(filp); 2680be6d3e56SKentaro Takeda if (!error) 2681ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26821da177e4SLinus Torvalds if (!error) { 26837715b521SAl Viro error = do_truncate(path->dentry, 0, 2684d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2685e1181ee6SJeff Layton filp); 26861da177e4SLinus Torvalds } 26871da177e4SLinus Torvalds put_write_access(inode); 2688acd0c935SMimi Zohar return error; 26891da177e4SLinus Torvalds } 26901da177e4SLinus Torvalds 2691d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2692d57999e1SDave Hansen { 26938a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26948a5e929dSAl Viro flag--; 2695d57999e1SDave Hansen return flag; 2696d57999e1SDave Hansen } 2697d57999e1SDave Hansen 2698d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2699d18e9008SMiklos Szeredi { 2700d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2701d18e9008SMiklos Szeredi if (error) 2702d18e9008SMiklos Szeredi return error; 2703d18e9008SMiklos Szeredi 2704d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2705d18e9008SMiklos Szeredi if (error) 2706d18e9008SMiklos Szeredi return error; 2707d18e9008SMiklos Szeredi 2708d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2709d18e9008SMiklos Szeredi } 2710d18e9008SMiklos Szeredi 27111acf0af9SDavid Howells /* 27121acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 27131acf0af9SDavid Howells * dentry. 27141acf0af9SDavid Howells * 27151acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 27161acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 27171acf0af9SDavid Howells * 27181acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 27191acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 27201acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 27211acf0af9SDavid Howells * 27221acf0af9SDavid Howells * Returns an error code otherwise. 27231acf0af9SDavid Howells */ 27242675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 272530d90494SAl Viro struct path *path, struct file *file, 2726015c3bbcSMiklos Szeredi const struct open_flags *op, 272764894cf8SAl Viro bool got_write, bool need_lookup, 272847237687SAl Viro int *opened) 2729d18e9008SMiklos Szeredi { 2730d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2731d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2732d18e9008SMiklos Szeredi umode_t mode; 2733d18e9008SMiklos Szeredi int error; 2734d18e9008SMiklos Szeredi int acc_mode; 2735d18e9008SMiklos Szeredi int create_error = 0; 2736d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2737116cc022SMiklos Szeredi bool excl; 2738d18e9008SMiklos Szeredi 2739d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2740d18e9008SMiklos Szeredi 2741d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2742d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27432675a4ebSAl Viro error = -ENOENT; 2744d18e9008SMiklos Szeredi goto out; 2745d18e9008SMiklos Szeredi } 2746d18e9008SMiklos Szeredi 274762b259d8SMiklos Szeredi mode = op->mode; 2748d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2749d18e9008SMiklos Szeredi mode &= ~current_umask(); 2750d18e9008SMiklos Szeredi 2751116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2752116cc022SMiklos Szeredi if (excl) 2753d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2754d18e9008SMiklos Szeredi 2755d18e9008SMiklos Szeredi /* 2756d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2757d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2758d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2759d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2760d18e9008SMiklos Szeredi * 2761d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2762d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2763d18e9008SMiklos Szeredi */ 276464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 276564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 276664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2767d18e9008SMiklos Szeredi /* 2768d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2769d18e9008SMiklos Szeredi * back to lookup + open 2770d18e9008SMiklos Szeredi */ 2771d18e9008SMiklos Szeredi goto no_open; 2772d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2773d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 277464894cf8SAl Viro create_error = -EROFS; 2775d18e9008SMiklos Szeredi goto no_open; 2776d18e9008SMiklos Szeredi } else { 2777d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 277864894cf8SAl Viro create_error = -EROFS; 2779d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2780d18e9008SMiklos Szeredi } 2781d18e9008SMiklos Szeredi } 2782d18e9008SMiklos Szeredi 2783d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 278438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2785d18e9008SMiklos Szeredi if (error) { 2786d18e9008SMiklos Szeredi create_error = error; 2787d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2788d18e9008SMiklos Szeredi goto no_open; 2789d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2790d18e9008SMiklos Szeredi } 2791d18e9008SMiklos Szeredi } 2792d18e9008SMiklos Szeredi 2793d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2794d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2795d18e9008SMiklos Szeredi 279630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 279730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 279830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 279947237687SAl Viro opened); 2800d9585277SAl Viro if (error < 0) { 2801d9585277SAl Viro if (create_error && error == -ENOENT) 2802d9585277SAl Viro error = create_error; 2803d18e9008SMiklos Szeredi goto out; 2804d18e9008SMiklos Szeredi } 2805d18e9008SMiklos Szeredi 2806d9585277SAl Viro if (error) { /* returned 1, that is */ 280730d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 28082675a4ebSAl Viro error = -EIO; 2809d18e9008SMiklos Szeredi goto out; 2810d18e9008SMiklos Szeredi } 281130d90494SAl Viro if (file->f_path.dentry) { 2812d18e9008SMiklos Szeredi dput(dentry); 281330d90494SAl Viro dentry = file->f_path.dentry; 2814d18e9008SMiklos Szeredi } 281503da633aSAl Viro if (*opened & FILE_CREATED) 281603da633aSAl Viro fsnotify_create(dir, dentry); 281703da633aSAl Viro if (!dentry->d_inode) { 281803da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 281903da633aSAl Viro if (create_error) { 282062b2ce96SSage Weil error = create_error; 282162b2ce96SSage Weil goto out; 282262b2ce96SSage Weil } 282303da633aSAl Viro } else { 282403da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 282503da633aSAl Viro error = -EEXIST; 282603da633aSAl Viro goto out; 282703da633aSAl Viro } 282803da633aSAl Viro } 2829d18e9008SMiklos Szeredi goto looked_up; 2830d18e9008SMiklos Szeredi } 2831d18e9008SMiklos Szeredi 2832d18e9008SMiklos Szeredi /* 2833d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2834d18e9008SMiklos Szeredi * here. 2835d18e9008SMiklos Szeredi */ 283603da633aSAl Viro acc_mode = op->acc_mode; 283703da633aSAl Viro if (*opened & FILE_CREATED) { 283803da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 283903da633aSAl Viro fsnotify_create(dir, dentry); 284003da633aSAl Viro acc_mode = MAY_OPEN; 284103da633aSAl Viro } 28422675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28432675a4ebSAl Viro if (error) 28442675a4ebSAl Viro fput(file); 2845d18e9008SMiklos Szeredi 2846d18e9008SMiklos Szeredi out: 2847d18e9008SMiklos Szeredi dput(dentry); 28482675a4ebSAl Viro return error; 2849d18e9008SMiklos Szeredi 2850d18e9008SMiklos Szeredi no_open: 2851d18e9008SMiklos Szeredi if (need_lookup) { 285272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2853d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28542675a4ebSAl Viro return PTR_ERR(dentry); 2855d18e9008SMiklos Szeredi 2856d18e9008SMiklos Szeredi if (create_error) { 2857d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2858d18e9008SMiklos Szeredi 28592675a4ebSAl Viro error = create_error; 2860d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2861d18e9008SMiklos Szeredi if (!dentry->d_inode) 2862d18e9008SMiklos Szeredi goto out; 2863d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2864d18e9008SMiklos Szeredi goto out; 2865d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2866e36cb0b8SDavid Howells d_is_reg(dentry)) { 2867d18e9008SMiklos Szeredi goto out; 2868d18e9008SMiklos Szeredi } 2869d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2870d18e9008SMiklos Szeredi } 2871d18e9008SMiklos Szeredi } 2872d18e9008SMiklos Szeredi looked_up: 2873d18e9008SMiklos Szeredi path->dentry = dentry; 2874d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28752675a4ebSAl Viro return 1; 2876d18e9008SMiklos Szeredi } 2877d18e9008SMiklos Szeredi 287831e6b01fSNick Piggin /* 28791acf0af9SDavid Howells * Look up and maybe create and open the last component. 2880d58ffd35SMiklos Szeredi * 2881d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2882d58ffd35SMiklos Szeredi * 28831acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28841acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28851acf0af9SDavid Howells * 28861acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28871acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28881acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28891acf0af9SDavid Howells * specified then a negative dentry may be returned. 28901acf0af9SDavid Howells * 28911acf0af9SDavid Howells * An error code is returned otherwise. 28921acf0af9SDavid Howells * 28931acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28941acf0af9SDavid Howells * cleared otherwise prior to returning. 2895d58ffd35SMiklos Szeredi */ 28962675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 289730d90494SAl Viro struct file *file, 2898d58ffd35SMiklos Szeredi const struct open_flags *op, 289964894cf8SAl Viro bool got_write, int *opened) 2900d58ffd35SMiklos Szeredi { 2901d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 290254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2903d58ffd35SMiklos Szeredi struct dentry *dentry; 2904d58ffd35SMiklos Szeredi int error; 290554ef4872SMiklos Szeredi bool need_lookup; 2906d58ffd35SMiklos Szeredi 290747237687SAl Viro *opened &= ~FILE_CREATED; 2908201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2909d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 29102675a4ebSAl Viro return PTR_ERR(dentry); 2911d58ffd35SMiklos Szeredi 2912d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2913d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2914d18e9008SMiklos Szeredi goto out_no_open; 2915d18e9008SMiklos Szeredi 2916d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 291764894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 291847237687SAl Viro need_lookup, opened); 2919d18e9008SMiklos Szeredi } 2920d18e9008SMiklos Szeredi 292154ef4872SMiklos Szeredi if (need_lookup) { 292254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 292354ef4872SMiklos Szeredi 292472bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 292554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 29262675a4ebSAl Viro return PTR_ERR(dentry); 292754ef4872SMiklos Szeredi } 292854ef4872SMiklos Szeredi 2929d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2930d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2931d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2932d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2933d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2934d58ffd35SMiklos Szeredi /* 2935d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2936d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2937d58ffd35SMiklos Szeredi * the time when the file is created and when 2938d58ffd35SMiklos Szeredi * a permanent write count is taken through 2939015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2940d58ffd35SMiklos Szeredi */ 294164894cf8SAl Viro if (!got_write) { 294264894cf8SAl Viro error = -EROFS; 2943d58ffd35SMiklos Szeredi goto out_dput; 294464894cf8SAl Viro } 294547237687SAl Viro *opened |= FILE_CREATED; 2946d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2947d58ffd35SMiklos Szeredi if (error) 2948d58ffd35SMiklos Szeredi goto out_dput; 2949312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2950312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2951d58ffd35SMiklos Szeredi if (error) 2952d58ffd35SMiklos Szeredi goto out_dput; 2953d58ffd35SMiklos Szeredi } 2954d18e9008SMiklos Szeredi out_no_open: 2955d58ffd35SMiklos Szeredi path->dentry = dentry; 2956d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29572675a4ebSAl Viro return 1; 2958d58ffd35SMiklos Szeredi 2959d58ffd35SMiklos Szeredi out_dput: 2960d58ffd35SMiklos Szeredi dput(dentry); 29612675a4ebSAl Viro return error; 2962d58ffd35SMiklos Szeredi } 2963d58ffd35SMiklos Szeredi 2964d58ffd35SMiklos Szeredi /* 2965fe2d35ffSAl Viro * Handle the last step of open() 296631e6b01fSNick Piggin */ 2967896475d5SAl Viro static int do_last(struct nameidata *nd, 296830d90494SAl Viro struct file *file, const struct open_flags *op, 2969669abf4eSJeff Layton int *opened, struct filename *name) 2970fb1cc555SAl Viro { 2971a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2972ca344a89SAl Viro int open_flag = op->open_flag; 297377d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 297464894cf8SAl Viro bool got_write = false; 2975bcda7652SAl Viro int acc_mode = op->acc_mode; 2976a1eb3315SMiklos Szeredi struct inode *inode; 297716b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2978896475d5SAl Viro struct path path; 297916b1c1cdSMiklos Szeredi bool retried = false; 298016c2cd71SAl Viro int error; 2981fb1cc555SAl Viro 2982c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2983c3e380b0SAl Viro nd->flags |= op->intent; 2984c3e380b0SAl Viro 2985bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2986fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2987fe2d35ffSAl Viro if (error) 29882675a4ebSAl Viro return error; 2989e83db167SMiklos Szeredi goto finish_open; 29901f36f774SAl Viro } 2991a2c36b45SAl Viro 2992ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2993fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2994fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2995fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2996896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 299771574865SMiklos Szeredi if (likely(!error)) 299871574865SMiklos Szeredi goto finish_lookup; 299971574865SMiklos Szeredi 3000ce57dfc1SAl Viro if (error < 0) 30012675a4ebSAl Viro goto out; 3002a1eb3315SMiklos Szeredi 300337d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 3004b6183df7SMiklos Szeredi } else { 3005fe2d35ffSAl Viro /* create side of things */ 3006a3fbbde7SAl Viro /* 3007b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3008b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3009b6183df7SMiklos Szeredi * about to look up 3010a3fbbde7SAl Viro */ 30119f1fafeeSAl Viro error = complete_walk(nd); 30129f1fafeeSAl Viro if (error) 30132675a4ebSAl Viro return error; 3014fe2d35ffSAl Viro 301533e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 301616c2cd71SAl Viro error = -EISDIR; 30171f36f774SAl Viro /* trailing slashes? */ 301831e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 30192675a4ebSAl Viro goto out; 3020b6183df7SMiklos Szeredi } 30211f36f774SAl Viro 302216b1c1cdSMiklos Szeredi retry_lookup: 302364894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 302464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 302564894cf8SAl Viro if (!error) 302664894cf8SAl Viro got_write = true; 302764894cf8SAl Viro /* 302864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 302964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 303064894cf8SAl Viro * dropping this one anyway. 303164894cf8SAl Viro */ 303264894cf8SAl Viro } 3033a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3034896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3035fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3036fb1cc555SAl Viro 30372675a4ebSAl Viro if (error <= 0) { 30382675a4ebSAl Viro if (error) 3039d58ffd35SMiklos Szeredi goto out; 30406c0d46c4SAl Viro 304147237687SAl Viro if ((*opened & FILE_CREATED) || 3042496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 304377d660a8SMiklos Szeredi will_truncate = false; 3044d18e9008SMiklos Szeredi 3045adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3046d18e9008SMiklos Szeredi goto opened; 3047d18e9008SMiklos Szeredi } 3048d18e9008SMiklos Szeredi 304947237687SAl Viro if (*opened & FILE_CREATED) { 30509b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3051ca344a89SAl Viro open_flag &= ~O_TRUNC; 305277d660a8SMiklos Szeredi will_truncate = false; 3053bcda7652SAl Viro acc_mode = MAY_OPEN; 3054896475d5SAl Viro path_to_nameidata(&path, nd); 3055e83db167SMiklos Szeredi goto finish_open_created; 3056fb1cc555SAl Viro } 3057fb1cc555SAl Viro 3058fb1cc555SAl Viro /* 30593134f37eSJeff Layton * create/update audit record if it already exists. 3060fb1cc555SAl Viro */ 3061896475d5SAl Viro if (d_is_positive(path.dentry)) 3062896475d5SAl Viro audit_inode(name, path.dentry, 0); 3063fb1cc555SAl Viro 3064d18e9008SMiklos Szeredi /* 3065d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3066d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3067d18e9008SMiklos Szeredi * necessary...) 3068d18e9008SMiklos Szeredi */ 306964894cf8SAl Viro if (got_write) { 3070d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 307164894cf8SAl Viro got_write = false; 3072d18e9008SMiklos Szeredi } 3073d18e9008SMiklos Szeredi 3074fb1cc555SAl Viro error = -EEXIST; 3075f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3076fb1cc555SAl Viro goto exit_dput; 3077fb1cc555SAl Viro 3078896475d5SAl Viro error = follow_managed(&path, nd->flags); 30799875cf80SDavid Howells if (error < 0) 3080fb1cc555SAl Viro goto exit_dput; 3081fb1cc555SAl Viro 3082a3fbbde7SAl Viro if (error) 3083a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3084a3fbbde7SAl Viro 3085decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3086896475d5SAl Viro inode = path.dentry->d_inode; 3087fb1cc555SAl Viro error = -ENOENT; 3088896475d5SAl Viro if (d_is_negative(path.dentry)) { 3089896475d5SAl Viro path_to_nameidata(&path, nd); 30902675a4ebSAl Viro goto out; 309154c33e7fSMiklos Szeredi } 3092766c4cbfSAl Viro finish_lookup: 3093896475d5SAl Viro if (should_follow_link(path.dentry, nd->flags & LOOKUP_FOLLOW)) { 3094d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3095896475d5SAl Viro if (unlikely(nd->path.mnt != path.mnt || 3096896475d5SAl Viro unlazy_walk(nd, path.dentry))) { 3097d45ea867SMiklos Szeredi error = -ECHILD; 30982675a4ebSAl Viro goto out; 3099d45ea867SMiklos Szeredi } 3100d45ea867SMiklos Szeredi } 3101896475d5SAl Viro BUG_ON(inode != path.dentry->d_inode); 3102896475d5SAl Viro nd->link = path; 31032675a4ebSAl Viro return 1; 3104d45ea867SMiklos Szeredi } 3105fb1cc555SAl Viro 3106896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3107896475d5SAl Viro path_to_nameidata(&path, nd); 3108a5cfe2d5SAl Viro error = -ELOOP; 3109a5cfe2d5SAl Viro goto out; 3110a5cfe2d5SAl Viro } 3111a5cfe2d5SAl Viro 3112896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3113896475d5SAl Viro path_to_nameidata(&path, nd); 311416b1c1cdSMiklos Szeredi } else { 311516b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3116896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3117896475d5SAl Viro nd->path.dentry = path.dentry; 311816b1c1cdSMiklos Szeredi 311916b1c1cdSMiklos Szeredi } 3120decf3400SMiklos Szeredi nd->inode = inode; 3121a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3122bc77daa7SAl Viro finish_open: 3123a3fbbde7SAl Viro error = complete_walk(nd); 312416b1c1cdSMiklos Szeredi if (error) { 312516b1c1cdSMiklos Szeredi path_put(&save_parent); 31262675a4ebSAl Viro return error; 312716b1c1cdSMiklos Szeredi } 3128bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3129fb1cc555SAl Viro error = -EISDIR; 313044b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31312675a4ebSAl Viro goto out; 3132af2f5542SMiklos Szeredi error = -ENOTDIR; 313344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31342675a4ebSAl Viro goto out; 31354bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 313677d660a8SMiklos Szeredi will_truncate = false; 31376c0d46c4SAl Viro 31380f9d1a10SAl Viro if (will_truncate) { 31390f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31400f9d1a10SAl Viro if (error) 31412675a4ebSAl Viro goto out; 314264894cf8SAl Viro got_write = true; 31430f9d1a10SAl Viro } 3144e83db167SMiklos Szeredi finish_open_created: 3145bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3146ca344a89SAl Viro if (error) 31472675a4ebSAl Viro goto out; 31484aa7c634SMiklos Szeredi 31494aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31504aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31514aa7c634SMiklos Szeredi if (!error) { 31524aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31534aa7c634SMiklos Szeredi } else { 315430d90494SAl Viro if (error == -EOPENSTALE) 3155f60dc3dbSMiklos Szeredi goto stale_open; 3156015c3bbcSMiklos Szeredi goto out; 3157f60dc3dbSMiklos Szeredi } 3158a8277b9bSMiklos Szeredi opened: 31592675a4ebSAl Viro error = open_check_o_direct(file); 3160015c3bbcSMiklos Szeredi if (error) 3161015c3bbcSMiklos Szeredi goto exit_fput; 31623034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3163aa4caadbSMiklos Szeredi if (error) 3164aa4caadbSMiklos Szeredi goto exit_fput; 3165aa4caadbSMiklos Szeredi 31660f9d1a10SAl Viro if (will_truncate) { 31672675a4ebSAl Viro error = handle_truncate(file); 3168aa4caadbSMiklos Szeredi if (error) 3169aa4caadbSMiklos Szeredi goto exit_fput; 31700f9d1a10SAl Viro } 3171ca344a89SAl Viro out: 317264894cf8SAl Viro if (got_write) 31730f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 317416b1c1cdSMiklos Szeredi path_put(&save_parent); 3175e276ae67SMiklos Szeredi terminate_walk(nd); 31762675a4ebSAl Viro return error; 3177fb1cc555SAl Viro 3178fb1cc555SAl Viro exit_dput: 3179896475d5SAl Viro path_put_conditional(&path, nd); 3180ca344a89SAl Viro goto out; 3181015c3bbcSMiklos Szeredi exit_fput: 31822675a4ebSAl Viro fput(file); 31832675a4ebSAl Viro goto out; 3184015c3bbcSMiklos Szeredi 3185f60dc3dbSMiklos Szeredi stale_open: 3186f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3187f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3188f60dc3dbSMiklos Szeredi goto out; 3189f60dc3dbSMiklos Szeredi 3190f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3191f60dc3dbSMiklos Szeredi path_put(&nd->path); 3192f60dc3dbSMiklos Szeredi nd->path = save_parent; 3193f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3194f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3195f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 319664894cf8SAl Viro if (got_write) { 3197f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 319864894cf8SAl Viro got_write = false; 3199f60dc3dbSMiklos Szeredi } 3200f60dc3dbSMiklos Szeredi retried = true; 3201f60dc3dbSMiklos Szeredi goto retry_lookup; 3202fb1cc555SAl Viro } 3203fb1cc555SAl Viro 320460545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 320560545d0dSAl Viro struct nameidata *nd, int flags, 320660545d0dSAl Viro const struct open_flags *op, 320760545d0dSAl Viro struct file *file, int *opened) 320860545d0dSAl Viro { 320960545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 321060545d0dSAl Viro struct dentry *dentry, *child; 321160545d0dSAl Viro struct inode *dir; 32125eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 321360545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 321460545d0dSAl Viro if (unlikely(error)) 321560545d0dSAl Viro return error; 321660545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 321760545d0dSAl Viro if (unlikely(error)) 321860545d0dSAl Viro goto out; 321960545d0dSAl Viro /* we want directory to be writable */ 322060545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 322160545d0dSAl Viro if (error) 322260545d0dSAl Viro goto out2; 322360545d0dSAl Viro dentry = nd->path.dentry; 322460545d0dSAl Viro dir = dentry->d_inode; 322560545d0dSAl Viro if (!dir->i_op->tmpfile) { 322660545d0dSAl Viro error = -EOPNOTSUPP; 322760545d0dSAl Viro goto out2; 322860545d0dSAl Viro } 322960545d0dSAl Viro child = d_alloc(dentry, &name); 323060545d0dSAl Viro if (unlikely(!child)) { 323160545d0dSAl Viro error = -ENOMEM; 323260545d0dSAl Viro goto out2; 323360545d0dSAl Viro } 323460545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 323560545d0dSAl Viro nd->flags |= op->intent; 323660545d0dSAl Viro dput(nd->path.dentry); 323760545d0dSAl Viro nd->path.dentry = child; 323860545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 323960545d0dSAl Viro if (error) 324060545d0dSAl Viro goto out2; 324160545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 324269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 324369a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 324460545d0dSAl Viro if (error) 324560545d0dSAl Viro goto out2; 324660545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 324760545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 324860545d0dSAl Viro if (error) 324960545d0dSAl Viro goto out2; 325060545d0dSAl Viro error = open_check_o_direct(file); 3251f4e0c30cSAl Viro if (error) { 325260545d0dSAl Viro fput(file); 3253f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3254f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3255f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3256f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3257f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3258f4e0c30cSAl Viro } 325960545d0dSAl Viro out2: 326060545d0dSAl Viro mnt_drop_write(nd->path.mnt); 326160545d0dSAl Viro out: 326260545d0dSAl Viro path_put(&nd->path); 326360545d0dSAl Viro return error; 326460545d0dSAl Viro } 326560545d0dSAl Viro 3266669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 326773d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32681da177e4SLinus Torvalds { 326930d90494SAl Viro struct file *file; 327047237687SAl Viro int opened = 0; 327113aab428SAl Viro int error; 327231e6b01fSNick Piggin 327330d90494SAl Viro file = get_empty_filp(); 32741afc99beSAl Viro if (IS_ERR(file)) 32751afc99beSAl Viro return file; 327631e6b01fSNick Piggin 327730d90494SAl Viro file->f_flags = op->open_flag; 327831e6b01fSNick Piggin 3279bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 328060545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3281f15133dfSAl Viro goto out2; 328260545d0dSAl Viro } 328360545d0dSAl Viro 32846e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 328531e6b01fSNick Piggin if (unlikely(error)) 32862675a4ebSAl Viro goto out; 32871da177e4SLinus Torvalds 3288896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 32892675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 329073d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32911d8e03d3SAl Viro error = trailing_symlink(nd); 3292c3e380b0SAl Viro if (unlikely(error)) 32932675a4ebSAl Viro break; 3294896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 3295b9ff4429SAl Viro put_link(nd); 3296806b681cSAl Viro } 329710fa8e62SAl Viro out: 3298893b7775SAl Viro path_cleanup(nd); 3299f15133dfSAl Viro out2: 33002675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 33012675a4ebSAl Viro BUG_ON(!error); 330230d90494SAl Viro put_filp(file); 3303015c3bbcSMiklos Szeredi } 33042675a4ebSAl Viro if (unlikely(error)) { 33052675a4ebSAl Viro if (error == -EOPENSTALE) { 33062675a4ebSAl Viro if (flags & LOOKUP_RCU) 33072675a4ebSAl Viro error = -ECHILD; 33082675a4ebSAl Viro else 33092675a4ebSAl Viro error = -ESTALE; 33102675a4ebSAl Viro } 33112675a4ebSAl Viro file = ERR_PTR(error); 33122675a4ebSAl Viro } 33132675a4ebSAl Viro return file; 3314de459215SKirill Korotaev } 33151da177e4SLinus Torvalds 3316669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3317f9652e10SAl Viro const struct open_flags *op) 331813aab428SAl Viro { 331973d049a4SAl Viro struct nameidata nd; 3320f9652e10SAl Viro int flags = op->lookup_flags; 332113aab428SAl Viro struct file *filp; 332213aab428SAl Viro 3323894bc8c4SAl Viro set_nameidata(&nd); 332473d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 332513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 332673d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 332713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 332873d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3329894bc8c4SAl Viro restore_nameidata(&nd); 333013aab428SAl Viro return filp; 333113aab428SAl Viro } 333213aab428SAl Viro 333373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3334f9652e10SAl Viro const char *name, const struct open_flags *op) 333573d049a4SAl Viro { 333673d049a4SAl Viro struct nameidata nd; 333773d049a4SAl Viro struct file *file; 333851689104SPaul Moore struct filename *filename; 3339f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 334073d049a4SAl Viro 334173d049a4SAl Viro nd.root.mnt = mnt; 334273d049a4SAl Viro nd.root.dentry = dentry; 3343894bc8c4SAl Viro set_nameidata(&nd); 334473d049a4SAl Viro 3345b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 334673d049a4SAl Viro return ERR_PTR(-ELOOP); 334773d049a4SAl Viro 334851689104SPaul Moore filename = getname_kernel(name); 334951689104SPaul Moore if (unlikely(IS_ERR(filename))) 335051689104SPaul Moore return ERR_CAST(filename); 335151689104SPaul Moore 335251689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 335373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 335451689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 335573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 335651689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3357894bc8c4SAl Viro restore_nameidata(&nd); 335851689104SPaul Moore putname(filename); 335973d049a4SAl Viro return file; 336073d049a4SAl Viro } 336173d049a4SAl Viro 3362fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33631ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33641da177e4SLinus Torvalds { 3365c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3366ed75e95dSAl Viro struct nameidata nd; 3367c30dabfeSJan Kara int err2; 33681ac12b4bSJeff Layton int error; 33691ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33701ac12b4bSJeff Layton 33711ac12b4bSJeff Layton /* 33721ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33731ac12b4bSJeff Layton * other flags passed in are ignored! 33741ac12b4bSJeff Layton */ 33751ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33761ac12b4bSJeff Layton 3377fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3378ed75e95dSAl Viro if (error) 3379ed75e95dSAl Viro return ERR_PTR(error); 33801da177e4SLinus Torvalds 3381c663e5d8SChristoph Hellwig /* 3382c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3383c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3384c663e5d8SChristoph Hellwig */ 3385ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3386ed75e95dSAl Viro goto out; 3387ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3388ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3389c663e5d8SChristoph Hellwig 3390c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3391c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3392c663e5d8SChristoph Hellwig /* 3393c663e5d8SChristoph Hellwig * Do the final lookup. 3394c663e5d8SChristoph Hellwig */ 3395ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33966a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33971da177e4SLinus Torvalds if (IS_ERR(dentry)) 3398a8104a9fSAl Viro goto unlock; 3399c663e5d8SChristoph Hellwig 3400a8104a9fSAl Viro error = -EEXIST; 3401b18825a7SDavid Howells if (d_is_positive(dentry)) 3402a8104a9fSAl Viro goto fail; 3403b18825a7SDavid Howells 3404c663e5d8SChristoph Hellwig /* 3405c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3406c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3407c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3408c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3409c663e5d8SChristoph Hellwig */ 3410ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3411a8104a9fSAl Viro error = -ENOENT; 3412ed75e95dSAl Viro goto fail; 3413e9baf6e5SAl Viro } 3414c30dabfeSJan Kara if (unlikely(err2)) { 3415c30dabfeSJan Kara error = err2; 3416a8104a9fSAl Viro goto fail; 3417c30dabfeSJan Kara } 3418ed75e95dSAl Viro *path = nd.path; 3419e9baf6e5SAl Viro return dentry; 34201da177e4SLinus Torvalds fail: 3421a8104a9fSAl Viro dput(dentry); 3422a8104a9fSAl Viro dentry = ERR_PTR(error); 3423a8104a9fSAl Viro unlock: 3424dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3425c30dabfeSJan Kara if (!err2) 3426c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3427ed75e95dSAl Viro out: 3428dae6ad8fSAl Viro path_put(&nd.path); 3429ed75e95dSAl Viro return dentry; 3430dae6ad8fSAl Viro } 3431fa14a0b8SAl Viro 3432fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3433fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3434fa14a0b8SAl Viro { 343551689104SPaul Moore struct filename *filename = getname_kernel(pathname); 343651689104SPaul Moore struct dentry *res; 343751689104SPaul Moore 343851689104SPaul Moore if (IS_ERR(filename)) 343951689104SPaul Moore return ERR_CAST(filename); 344051689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 344151689104SPaul Moore putname(filename); 344251689104SPaul Moore return res; 3443fa14a0b8SAl Viro } 3444dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3445dae6ad8fSAl Viro 3446921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3447921a1650SAl Viro { 3448921a1650SAl Viro dput(dentry); 3449921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3450a8104a9fSAl Viro mnt_drop_write(path->mnt); 3451921a1650SAl Viro path_put(path); 3452921a1650SAl Viro } 3453921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3454921a1650SAl Viro 34551ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34561ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3457dae6ad8fSAl Viro { 345891a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3459dae6ad8fSAl Viro struct dentry *res; 3460dae6ad8fSAl Viro if (IS_ERR(tmp)) 3461dae6ad8fSAl Viro return ERR_CAST(tmp); 3462fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3463dae6ad8fSAl Viro putname(tmp); 3464dae6ad8fSAl Viro return res; 3465dae6ad8fSAl Viro } 3466dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3467dae6ad8fSAl Viro 34681a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34691da177e4SLinus Torvalds { 3470a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34711da177e4SLinus Torvalds 34721da177e4SLinus Torvalds if (error) 34731da177e4SLinus Torvalds return error; 34741da177e4SLinus Torvalds 3475975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34761da177e4SLinus Torvalds return -EPERM; 34771da177e4SLinus Torvalds 3478acfa4380SAl Viro if (!dir->i_op->mknod) 34791da177e4SLinus Torvalds return -EPERM; 34801da177e4SLinus Torvalds 348108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 348208ce5f16SSerge E. Hallyn if (error) 348308ce5f16SSerge E. Hallyn return error; 348408ce5f16SSerge E. Hallyn 34851da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34861da177e4SLinus Torvalds if (error) 34871da177e4SLinus Torvalds return error; 34881da177e4SLinus Torvalds 34891da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3490a74574aaSStephen Smalley if (!error) 3491f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34921da177e4SLinus Torvalds return error; 34931da177e4SLinus Torvalds } 34944d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34951da177e4SLinus Torvalds 3496f69aac00SAl Viro static int may_mknod(umode_t mode) 3497463c3197SDave Hansen { 3498463c3197SDave Hansen switch (mode & S_IFMT) { 3499463c3197SDave Hansen case S_IFREG: 3500463c3197SDave Hansen case S_IFCHR: 3501463c3197SDave Hansen case S_IFBLK: 3502463c3197SDave Hansen case S_IFIFO: 3503463c3197SDave Hansen case S_IFSOCK: 3504463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3505463c3197SDave Hansen return 0; 3506463c3197SDave Hansen case S_IFDIR: 3507463c3197SDave Hansen return -EPERM; 3508463c3197SDave Hansen default: 3509463c3197SDave Hansen return -EINVAL; 3510463c3197SDave Hansen } 3511463c3197SDave Hansen } 3512463c3197SDave Hansen 35138208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 35142e4d0924SHeiko Carstens unsigned, dev) 35151da177e4SLinus Torvalds { 35161da177e4SLinus Torvalds struct dentry *dentry; 3517dae6ad8fSAl Viro struct path path; 3518dae6ad8fSAl Viro int error; 3519972567f1SJeff Layton unsigned int lookup_flags = 0; 35201da177e4SLinus Torvalds 35218e4bfca1SAl Viro error = may_mknod(mode); 35228e4bfca1SAl Viro if (error) 35238e4bfca1SAl Viro return error; 3524972567f1SJeff Layton retry: 3525972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3526dae6ad8fSAl Viro if (IS_ERR(dentry)) 3527dae6ad8fSAl Viro return PTR_ERR(dentry); 35282ad94ae6SAl Viro 3529dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3530ce3b0f8dSAl Viro mode &= ~current_umask(); 3531dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3532be6d3e56SKentaro Takeda if (error) 3533a8104a9fSAl Viro goto out; 35341da177e4SLinus Torvalds switch (mode & S_IFMT) { 35351da177e4SLinus Torvalds case 0: case S_IFREG: 3536312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35371da177e4SLinus Torvalds break; 35381da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3539dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35401da177e4SLinus Torvalds new_decode_dev(dev)); 35411da177e4SLinus Torvalds break; 35421da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3543dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35441da177e4SLinus Torvalds break; 35451da177e4SLinus Torvalds } 3546a8104a9fSAl Viro out: 3547921a1650SAl Viro done_path_create(&path, dentry); 3548972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3549972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3550972567f1SJeff Layton goto retry; 3551972567f1SJeff Layton } 35521da177e4SLinus Torvalds return error; 35531da177e4SLinus Torvalds } 35541da177e4SLinus Torvalds 35558208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35565590ff0dSUlrich Drepper { 35575590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35585590ff0dSUlrich Drepper } 35595590ff0dSUlrich Drepper 356018bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35611da177e4SLinus Torvalds { 3562a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35638de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35641da177e4SLinus Torvalds 35651da177e4SLinus Torvalds if (error) 35661da177e4SLinus Torvalds return error; 35671da177e4SLinus Torvalds 3568acfa4380SAl Viro if (!dir->i_op->mkdir) 35691da177e4SLinus Torvalds return -EPERM; 35701da177e4SLinus Torvalds 35711da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35721da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35731da177e4SLinus Torvalds if (error) 35741da177e4SLinus Torvalds return error; 35751da177e4SLinus Torvalds 35768de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35778de52778SAl Viro return -EMLINK; 35788de52778SAl Viro 35791da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3580a74574aaSStephen Smalley if (!error) 3581f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35821da177e4SLinus Torvalds return error; 35831da177e4SLinus Torvalds } 35844d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35851da177e4SLinus Torvalds 3586a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35871da177e4SLinus Torvalds { 35886902d925SDave Hansen struct dentry *dentry; 3589dae6ad8fSAl Viro struct path path; 3590dae6ad8fSAl Viro int error; 3591b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35921da177e4SLinus Torvalds 3593b76d8b82SJeff Layton retry: 3594b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35956902d925SDave Hansen if (IS_ERR(dentry)) 3596dae6ad8fSAl Viro return PTR_ERR(dentry); 35976902d925SDave Hansen 3598dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3599ce3b0f8dSAl Viro mode &= ~current_umask(); 3600dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3601a8104a9fSAl Viro if (!error) 3602dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3603921a1650SAl Viro done_path_create(&path, dentry); 3604b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3605b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3606b76d8b82SJeff Layton goto retry; 3607b76d8b82SJeff Layton } 36081da177e4SLinus Torvalds return error; 36091da177e4SLinus Torvalds } 36101da177e4SLinus Torvalds 3611a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36125590ff0dSUlrich Drepper { 36135590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 36145590ff0dSUlrich Drepper } 36155590ff0dSUlrich Drepper 36161da177e4SLinus Torvalds /* 3617a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3618c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3619a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3620a71905f0SSage Weil * then we drop the dentry now. 36211da177e4SLinus Torvalds * 36221da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 36231da177e4SLinus Torvalds * do a 36241da177e4SLinus Torvalds * 36251da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 36261da177e4SLinus Torvalds * return -EBUSY; 36271da177e4SLinus Torvalds * 36281da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 36291da177e4SLinus Torvalds * that is still in use by something else.. 36301da177e4SLinus Torvalds */ 36311da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36321da177e4SLinus Torvalds { 36331da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36341da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 363598474236SWaiman Long if (dentry->d_lockref.count == 1) 36361da177e4SLinus Torvalds __d_drop(dentry); 36371da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36381da177e4SLinus Torvalds } 36394d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36401da177e4SLinus Torvalds 36411da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36421da177e4SLinus Torvalds { 36431da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36441da177e4SLinus Torvalds 36451da177e4SLinus Torvalds if (error) 36461da177e4SLinus Torvalds return error; 36471da177e4SLinus Torvalds 3648acfa4380SAl Viro if (!dir->i_op->rmdir) 36491da177e4SLinus Torvalds return -EPERM; 36501da177e4SLinus Torvalds 36511d2ef590SAl Viro dget(dentry); 36521b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3653912dbc15SSage Weil 36541da177e4SLinus Torvalds error = -EBUSY; 36557af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3656912dbc15SSage Weil goto out; 3657912dbc15SSage Weil 36581da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3659912dbc15SSage Weil if (error) 3660912dbc15SSage Weil goto out; 3661912dbc15SSage Weil 36623cebde24SSage Weil shrink_dcache_parent(dentry); 36631da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3664912dbc15SSage Weil if (error) 3665912dbc15SSage Weil goto out; 3666912dbc15SSage Weil 36671da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3668d83c49f3SAl Viro dont_mount(dentry); 36698ed936b5SEric W. Biederman detach_mounts(dentry); 36701da177e4SLinus Torvalds 3671912dbc15SSage Weil out: 3672912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36731d2ef590SAl Viro dput(dentry); 3674912dbc15SSage Weil if (!error) 3675912dbc15SSage Weil d_delete(dentry); 36761da177e4SLinus Torvalds return error; 36771da177e4SLinus Torvalds } 36784d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36791da177e4SLinus Torvalds 36805590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36811da177e4SLinus Torvalds { 36821da177e4SLinus Torvalds int error = 0; 368391a27b2aSJeff Layton struct filename *name; 36841da177e4SLinus Torvalds struct dentry *dentry; 3685f5beed75SAl Viro struct path path; 3686f5beed75SAl Viro struct qstr last; 3687f5beed75SAl Viro int type; 3688c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3689c6ee9206SJeff Layton retry: 3690f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3691f5beed75SAl Viro &path, &last, &type, lookup_flags); 369291a27b2aSJeff Layton if (IS_ERR(name)) 369391a27b2aSJeff Layton return PTR_ERR(name); 36941da177e4SLinus Torvalds 3695f5beed75SAl Viro switch (type) { 36961da177e4SLinus Torvalds case LAST_DOTDOT: 36971da177e4SLinus Torvalds error = -ENOTEMPTY; 36981da177e4SLinus Torvalds goto exit1; 36991da177e4SLinus Torvalds case LAST_DOT: 37001da177e4SLinus Torvalds error = -EINVAL; 37011da177e4SLinus Torvalds goto exit1; 37021da177e4SLinus Torvalds case LAST_ROOT: 37031da177e4SLinus Torvalds error = -EBUSY; 37041da177e4SLinus Torvalds goto exit1; 37051da177e4SLinus Torvalds } 37060612d9fbSOGAWA Hirofumi 3707f5beed75SAl Viro error = mnt_want_write(path.mnt); 3708c30dabfeSJan Kara if (error) 3709c30dabfeSJan Kara goto exit1; 37100612d9fbSOGAWA Hirofumi 3711f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3712f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37131da177e4SLinus Torvalds error = PTR_ERR(dentry); 37146902d925SDave Hansen if (IS_ERR(dentry)) 37156902d925SDave Hansen goto exit2; 3716e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3717e6bc45d6STheodore Ts'o error = -ENOENT; 3718e6bc45d6STheodore Ts'o goto exit3; 3719e6bc45d6STheodore Ts'o } 3720f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3721be6d3e56SKentaro Takeda if (error) 3722c30dabfeSJan Kara goto exit3; 3723f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37240622753bSDave Hansen exit3: 37251da177e4SLinus Torvalds dput(dentry); 37266902d925SDave Hansen exit2: 3727f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3728f5beed75SAl Viro mnt_drop_write(path.mnt); 37291da177e4SLinus Torvalds exit1: 3730f5beed75SAl Viro path_put(&path); 37311da177e4SLinus Torvalds putname(name); 3732c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3733c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3734c6ee9206SJeff Layton goto retry; 3735c6ee9206SJeff Layton } 37361da177e4SLinus Torvalds return error; 37371da177e4SLinus Torvalds } 37381da177e4SLinus Torvalds 37393cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37405590ff0dSUlrich Drepper { 37415590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37425590ff0dSUlrich Drepper } 37435590ff0dSUlrich Drepper 3744b21996e3SJ. Bruce Fields /** 3745b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3746b21996e3SJ. Bruce Fields * @dir: parent directory 3747b21996e3SJ. Bruce Fields * @dentry: victim 3748b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3749b21996e3SJ. Bruce Fields * 3750b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3751b21996e3SJ. Bruce Fields * 3752b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3753b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3754b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3755b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3756b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3757b21996e3SJ. Bruce Fields * 3758b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3759b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3760b21996e3SJ. Bruce Fields * to be NFS exported. 3761b21996e3SJ. Bruce Fields */ 3762b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37631da177e4SLinus Torvalds { 37649accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37651da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37661da177e4SLinus Torvalds 37671da177e4SLinus Torvalds if (error) 37681da177e4SLinus Torvalds return error; 37691da177e4SLinus Torvalds 3770acfa4380SAl Viro if (!dir->i_op->unlink) 37711da177e4SLinus Torvalds return -EPERM; 37721da177e4SLinus Torvalds 37739accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37748ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37751da177e4SLinus Torvalds error = -EBUSY; 37761da177e4SLinus Torvalds else { 37771da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3778bec1052eSAl Viro if (!error) { 37795a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37805a14696cSJ. Bruce Fields if (error) 3781b21996e3SJ. Bruce Fields goto out; 37821da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37838ed936b5SEric W. Biederman if (!error) { 3784d83c49f3SAl Viro dont_mount(dentry); 37858ed936b5SEric W. Biederman detach_mounts(dentry); 37868ed936b5SEric W. Biederman } 3787bec1052eSAl Viro } 37881da177e4SLinus Torvalds } 3789b21996e3SJ. Bruce Fields out: 37909accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37911da177e4SLinus Torvalds 37921da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37931da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37949accbb97SJ. Bruce Fields fsnotify_link_count(target); 37951da177e4SLinus Torvalds d_delete(dentry); 37961da177e4SLinus Torvalds } 37970eeca283SRobert Love 37981da177e4SLinus Torvalds return error; 37991da177e4SLinus Torvalds } 38004d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38011da177e4SLinus Torvalds 38021da177e4SLinus Torvalds /* 38031da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38041b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38051da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38061da177e4SLinus Torvalds * while waiting on the I/O. 38071da177e4SLinus Torvalds */ 38085590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 38091da177e4SLinus Torvalds { 38102ad94ae6SAl Viro int error; 381191a27b2aSJeff Layton struct filename *name; 38121da177e4SLinus Torvalds struct dentry *dentry; 3813f5beed75SAl Viro struct path path; 3814f5beed75SAl Viro struct qstr last; 3815f5beed75SAl Viro int type; 38161da177e4SLinus Torvalds struct inode *inode = NULL; 3817b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38185d18f813SJeff Layton unsigned int lookup_flags = 0; 38195d18f813SJeff Layton retry: 3820f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3821f5beed75SAl Viro &path, &last, &type, lookup_flags); 382291a27b2aSJeff Layton if (IS_ERR(name)) 382391a27b2aSJeff Layton return PTR_ERR(name); 38242ad94ae6SAl Viro 38251da177e4SLinus Torvalds error = -EISDIR; 3826f5beed75SAl Viro if (type != LAST_NORM) 38271da177e4SLinus Torvalds goto exit1; 38280612d9fbSOGAWA Hirofumi 3829f5beed75SAl Viro error = mnt_want_write(path.mnt); 3830c30dabfeSJan Kara if (error) 3831c30dabfeSJan Kara goto exit1; 3832b21996e3SJ. Bruce Fields retry_deleg: 3833f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3834f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38351da177e4SLinus Torvalds error = PTR_ERR(dentry); 38361da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38371da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3838f5beed75SAl Viro if (last.name[last.len]) 383950338b88STörök Edwin goto slashes; 38401da177e4SLinus Torvalds inode = dentry->d_inode; 3841b18825a7SDavid Howells if (d_is_negative(dentry)) 3842e6bc45d6STheodore Ts'o goto slashes; 38437de9c6eeSAl Viro ihold(inode); 3844f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3845be6d3e56SKentaro Takeda if (error) 3846c30dabfeSJan Kara goto exit2; 3847f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38481da177e4SLinus Torvalds exit2: 38491da177e4SLinus Torvalds dput(dentry); 38501da177e4SLinus Torvalds } 3851f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38521da177e4SLinus Torvalds if (inode) 38531da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3854b21996e3SJ. Bruce Fields inode = NULL; 3855b21996e3SJ. Bruce Fields if (delegated_inode) { 38565a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3857b21996e3SJ. Bruce Fields if (!error) 3858b21996e3SJ. Bruce Fields goto retry_deleg; 3859b21996e3SJ. Bruce Fields } 3860f5beed75SAl Viro mnt_drop_write(path.mnt); 38611da177e4SLinus Torvalds exit1: 3862f5beed75SAl Viro path_put(&path); 38631da177e4SLinus Torvalds putname(name); 38645d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38655d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38665d18f813SJeff Layton inode = NULL; 38675d18f813SJeff Layton goto retry; 38685d18f813SJeff Layton } 38691da177e4SLinus Torvalds return error; 38701da177e4SLinus Torvalds 38711da177e4SLinus Torvalds slashes: 3872b18825a7SDavid Howells if (d_is_negative(dentry)) 3873b18825a7SDavid Howells error = -ENOENT; 387444b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3875b18825a7SDavid Howells error = -EISDIR; 3876b18825a7SDavid Howells else 3877b18825a7SDavid Howells error = -ENOTDIR; 38781da177e4SLinus Torvalds goto exit2; 38791da177e4SLinus Torvalds } 38801da177e4SLinus Torvalds 38812e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38825590ff0dSUlrich Drepper { 38835590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38845590ff0dSUlrich Drepper return -EINVAL; 38855590ff0dSUlrich Drepper 38865590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38875590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38885590ff0dSUlrich Drepper 38895590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38905590ff0dSUlrich Drepper } 38915590ff0dSUlrich Drepper 38923480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38935590ff0dSUlrich Drepper { 38945590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38955590ff0dSUlrich Drepper } 38965590ff0dSUlrich Drepper 3897db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38981da177e4SLinus Torvalds { 3899a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39001da177e4SLinus Torvalds 39011da177e4SLinus Torvalds if (error) 39021da177e4SLinus Torvalds return error; 39031da177e4SLinus Torvalds 3904acfa4380SAl Viro if (!dir->i_op->symlink) 39051da177e4SLinus Torvalds return -EPERM; 39061da177e4SLinus Torvalds 39071da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39081da177e4SLinus Torvalds if (error) 39091da177e4SLinus Torvalds return error; 39101da177e4SLinus Torvalds 39111da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3912a74574aaSStephen Smalley if (!error) 3913f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39141da177e4SLinus Torvalds return error; 39151da177e4SLinus Torvalds } 39164d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39171da177e4SLinus Torvalds 39182e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 39192e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 39201da177e4SLinus Torvalds { 39212ad94ae6SAl Viro int error; 392291a27b2aSJeff Layton struct filename *from; 39236902d925SDave Hansen struct dentry *dentry; 3924dae6ad8fSAl Viro struct path path; 3925f46d3567SJeff Layton unsigned int lookup_flags = 0; 39261da177e4SLinus Torvalds 39271da177e4SLinus Torvalds from = getname(oldname); 39281da177e4SLinus Torvalds if (IS_ERR(from)) 39291da177e4SLinus Torvalds return PTR_ERR(from); 3930f46d3567SJeff Layton retry: 3931f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39321da177e4SLinus Torvalds error = PTR_ERR(dentry); 39336902d925SDave Hansen if (IS_ERR(dentry)) 3934dae6ad8fSAl Viro goto out_putname; 39356902d925SDave Hansen 393691a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3937a8104a9fSAl Viro if (!error) 393891a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3939921a1650SAl Viro done_path_create(&path, dentry); 3940f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3941f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3942f46d3567SJeff Layton goto retry; 3943f46d3567SJeff Layton } 39446902d925SDave Hansen out_putname: 39451da177e4SLinus Torvalds putname(from); 39461da177e4SLinus Torvalds return error; 39471da177e4SLinus Torvalds } 39481da177e4SLinus Torvalds 39493480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39505590ff0dSUlrich Drepper { 39515590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39525590ff0dSUlrich Drepper } 39535590ff0dSUlrich Drepper 3954146a8595SJ. Bruce Fields /** 3955146a8595SJ. Bruce Fields * vfs_link - create a new link 3956146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3957146a8595SJ. Bruce Fields * @dir: new parent 3958146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3959146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3960146a8595SJ. Bruce Fields * 3961146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3962146a8595SJ. Bruce Fields * 3963146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3964146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3965146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3966146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3967146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3968146a8595SJ. Bruce Fields * 3969146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3970146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3971146a8595SJ. Bruce Fields * to be NFS exported. 3972146a8595SJ. Bruce Fields */ 3973146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39741da177e4SLinus Torvalds { 39751da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39768de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39771da177e4SLinus Torvalds int error; 39781da177e4SLinus Torvalds 39791da177e4SLinus Torvalds if (!inode) 39801da177e4SLinus Torvalds return -ENOENT; 39811da177e4SLinus Torvalds 3982a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39831da177e4SLinus Torvalds if (error) 39841da177e4SLinus Torvalds return error; 39851da177e4SLinus Torvalds 39861da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39871da177e4SLinus Torvalds return -EXDEV; 39881da177e4SLinus Torvalds 39891da177e4SLinus Torvalds /* 39901da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39911da177e4SLinus Torvalds */ 39921da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39931da177e4SLinus Torvalds return -EPERM; 3994acfa4380SAl Viro if (!dir->i_op->link) 39951da177e4SLinus Torvalds return -EPERM; 39967e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39971da177e4SLinus Torvalds return -EPERM; 39981da177e4SLinus Torvalds 39991da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40001da177e4SLinus Torvalds if (error) 40011da177e4SLinus Torvalds return error; 40021da177e4SLinus Torvalds 40037e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 4004aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4005f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4006aae8a97dSAneesh Kumar K.V error = -ENOENT; 40078de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40088de52778SAl Viro error = -EMLINK; 4009146a8595SJ. Bruce Fields else { 4010146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4011146a8595SJ. Bruce Fields if (!error) 40121da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4013146a8595SJ. Bruce Fields } 4014f4e0c30cSAl Viro 4015f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4016f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4017f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4018f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4019f4e0c30cSAl Viro } 40207e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 4021e31e14ecSStephen Smalley if (!error) 40227e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40231da177e4SLinus Torvalds return error; 40241da177e4SLinus Torvalds } 40254d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40261da177e4SLinus Torvalds 40271da177e4SLinus Torvalds /* 40281da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40291da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40301da177e4SLinus Torvalds * newname. --KAB 40311da177e4SLinus Torvalds * 40321da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40331da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40341da177e4SLinus Torvalds * and other special files. --ADM 40351da177e4SLinus Torvalds */ 40362e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40372e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40381da177e4SLinus Torvalds { 40391da177e4SLinus Torvalds struct dentry *new_dentry; 4040dae6ad8fSAl Viro struct path old_path, new_path; 4041146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 404211a7b371SAneesh Kumar K.V int how = 0; 40431da177e4SLinus Torvalds int error; 40441da177e4SLinus Torvalds 404511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4046c04030e1SUlrich Drepper return -EINVAL; 404711a7b371SAneesh Kumar K.V /* 4048f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4049f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4050f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 405111a7b371SAneesh Kumar K.V */ 4052f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4053f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4054f0cc6ffbSLinus Torvalds return -ENOENT; 405511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4056f0cc6ffbSLinus Torvalds } 4057c04030e1SUlrich Drepper 405811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 405911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4060442e31caSJeff Layton retry: 406111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40621da177e4SLinus Torvalds if (error) 40632ad94ae6SAl Viro return error; 40642ad94ae6SAl Viro 4065442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4066442e31caSJeff Layton (how & LOOKUP_REVAL)); 40671da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40686902d925SDave Hansen if (IS_ERR(new_dentry)) 4069dae6ad8fSAl Viro goto out; 4070dae6ad8fSAl Viro 4071dae6ad8fSAl Viro error = -EXDEV; 4072dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4073dae6ad8fSAl Viro goto out_dput; 4074800179c9SKees Cook error = may_linkat(&old_path); 4075800179c9SKees Cook if (unlikely(error)) 4076800179c9SKees Cook goto out_dput; 4077dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4078be6d3e56SKentaro Takeda if (error) 4079a8104a9fSAl Viro goto out_dput; 4080146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 408175c3f29dSDave Hansen out_dput: 4082921a1650SAl Viro done_path_create(&new_path, new_dentry); 4083146a8595SJ. Bruce Fields if (delegated_inode) { 4084146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4085d22e6338SOleg Drokin if (!error) { 4086d22e6338SOleg Drokin path_put(&old_path); 4087146a8595SJ. Bruce Fields goto retry; 4088146a8595SJ. Bruce Fields } 4089d22e6338SOleg Drokin } 4090442e31caSJeff Layton if (retry_estale(error, how)) { 4091d22e6338SOleg Drokin path_put(&old_path); 4092442e31caSJeff Layton how |= LOOKUP_REVAL; 4093442e31caSJeff Layton goto retry; 4094442e31caSJeff Layton } 40951da177e4SLinus Torvalds out: 40962d8f3038SAl Viro path_put(&old_path); 40971da177e4SLinus Torvalds 40981da177e4SLinus Torvalds return error; 40991da177e4SLinus Torvalds } 41001da177e4SLinus Torvalds 41013480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41025590ff0dSUlrich Drepper { 4103c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41045590ff0dSUlrich Drepper } 41055590ff0dSUlrich Drepper 4106bc27027aSMiklos Szeredi /** 4107bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4108bc27027aSMiklos Szeredi * @old_dir: parent of source 4109bc27027aSMiklos Szeredi * @old_dentry: source 4110bc27027aSMiklos Szeredi * @new_dir: parent of destination 4111bc27027aSMiklos Szeredi * @new_dentry: destination 4112bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4113520c8b16SMiklos Szeredi * @flags: rename flags 4114bc27027aSMiklos Szeredi * 4115bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4116bc27027aSMiklos Szeredi * 4117bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4118bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4119bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4120bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4121bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4122bc27027aSMiklos Szeredi * so. 4123bc27027aSMiklos Szeredi * 4124bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4125bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4126bc27027aSMiklos Szeredi * to be NFS exported. 4127bc27027aSMiklos Szeredi * 41281da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41291da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41301da177e4SLinus Torvalds * Problems: 4131d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41321da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41331da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4134a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41351da177e4SLinus Torvalds * story. 41366cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41376cedba89SJ. Bruce Fields * and source (if it is not a directory). 41381b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41391da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41401da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4141a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41421da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41431da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41441da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4145a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41461da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41471da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41481da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4149e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41501b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41511da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4152c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41531da177e4SLinus Torvalds * locking]. 41541da177e4SLinus Torvalds */ 41551da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41568e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4157520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41581da177e4SLinus Torvalds { 41591da177e4SLinus Torvalds int error; 4160bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 416159b0df21SEric Paris const unsigned char *old_name; 4162bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4163bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4164da1ce067SMiklos Szeredi bool new_is_dir = false; 4165da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41661da177e4SLinus Torvalds 4167bc27027aSMiklos Szeredi if (source == target) 41681da177e4SLinus Torvalds return 0; 41691da177e4SLinus Torvalds 41701da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41711da177e4SLinus Torvalds if (error) 41721da177e4SLinus Torvalds return error; 41731da177e4SLinus Torvalds 4174da1ce067SMiklos Szeredi if (!target) { 4175a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4176da1ce067SMiklos Szeredi } else { 4177da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4178da1ce067SMiklos Szeredi 4179da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41801da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4181da1ce067SMiklos Szeredi else 4182da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4183da1ce067SMiklos Szeredi } 41841da177e4SLinus Torvalds if (error) 41851da177e4SLinus Torvalds return error; 41861da177e4SLinus Torvalds 41877177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41881da177e4SLinus Torvalds return -EPERM; 41891da177e4SLinus Torvalds 4190520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4191520c8b16SMiklos Szeredi return -EINVAL; 4192520c8b16SMiklos Szeredi 4193bc27027aSMiklos Szeredi /* 4194bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4195bc27027aSMiklos Szeredi * we'll need to flip '..'. 4196bc27027aSMiklos Szeredi */ 4197da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4198da1ce067SMiklos Szeredi if (is_dir) { 4199bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4200bc27027aSMiklos Szeredi if (error) 4201bc27027aSMiklos Szeredi return error; 4202bc27027aSMiklos Szeredi } 4203da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4204da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4205da1ce067SMiklos Szeredi if (error) 4206da1ce067SMiklos Szeredi return error; 4207da1ce067SMiklos Szeredi } 4208da1ce067SMiklos Szeredi } 42090eeca283SRobert Love 42100b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42110b3974ebSMiklos Szeredi flags); 4212bc27027aSMiklos Szeredi if (error) 4213bc27027aSMiklos Szeredi return error; 4214bc27027aSMiklos Szeredi 4215bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4216bc27027aSMiklos Szeredi dget(new_dentry); 4217da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4218bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4219bc27027aSMiklos Szeredi else if (target) 4220bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4221bc27027aSMiklos Szeredi 4222bc27027aSMiklos Szeredi error = -EBUSY; 42237af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4224bc27027aSMiklos Szeredi goto out; 4225bc27027aSMiklos Szeredi 4226da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4227bc27027aSMiklos Szeredi error = -EMLINK; 4228da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4229bc27027aSMiklos Szeredi goto out; 4230da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4231da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4232da1ce067SMiklos Szeredi goto out; 4233da1ce067SMiklos Szeredi } 4234da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4235bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4236da1ce067SMiklos Szeredi if (!is_dir) { 4237bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4238bc27027aSMiklos Szeredi if (error) 4239bc27027aSMiklos Szeredi goto out; 4240da1ce067SMiklos Szeredi } 4241da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4242bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4243bc27027aSMiklos Szeredi if (error) 4244bc27027aSMiklos Szeredi goto out; 4245bc27027aSMiklos Szeredi } 42467177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4247520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4248520c8b16SMiklos Szeredi new_dir, new_dentry); 4249520c8b16SMiklos Szeredi } else { 42507177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4251520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4252520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4253520c8b16SMiklos Szeredi } 4254bc27027aSMiklos Szeredi if (error) 4255bc27027aSMiklos Szeredi goto out; 4256bc27027aSMiklos Szeredi 4257da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42581da177e4SLinus Torvalds if (is_dir) 4259bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4260bc27027aSMiklos Szeredi dont_mount(new_dentry); 42618ed936b5SEric W. Biederman detach_mounts(new_dentry); 4262bc27027aSMiklos Szeredi } 4263da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4264da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4265bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4266da1ce067SMiklos Szeredi else 4267da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4268da1ce067SMiklos Szeredi } 4269bc27027aSMiklos Szeredi out: 4270da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4271bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4272bc27027aSMiklos Szeredi else if (target) 4273bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4274bc27027aSMiklos Szeredi dput(new_dentry); 4275da1ce067SMiklos Szeredi if (!error) { 4276123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4277da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4278da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4279da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4280da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4281da1ce067SMiklos Szeredi } 4282da1ce067SMiklos Szeredi } 42830eeca283SRobert Love fsnotify_oldname_free(old_name); 42840eeca283SRobert Love 42851da177e4SLinus Torvalds return error; 42861da177e4SLinus Torvalds } 42874d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42881da177e4SLinus Torvalds 4289520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4290520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42911da177e4SLinus Torvalds { 42921da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42931da177e4SLinus Torvalds struct dentry *trap; 4294f5beed75SAl Viro struct path old_path, new_path; 4295f5beed75SAl Viro struct qstr old_last, new_last; 4296f5beed75SAl Viro int old_type, new_type; 42978e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 429891a27b2aSJeff Layton struct filename *from; 429991a27b2aSJeff Layton struct filename *to; 4300f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4301c6a94284SJeff Layton bool should_retry = false; 43022ad94ae6SAl Viro int error; 4303520c8b16SMiklos Szeredi 43040d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4305da1ce067SMiklos Szeredi return -EINVAL; 4306da1ce067SMiklos Szeredi 43070d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43080d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4309520c8b16SMiklos Szeredi return -EINVAL; 4310520c8b16SMiklos Szeredi 43110d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43120d7a8555SMiklos Szeredi return -EPERM; 43130d7a8555SMiklos Szeredi 4314f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4315f5beed75SAl Viro target_flags = 0; 4316f5beed75SAl Viro 4317c6a94284SJeff Layton retry: 4318f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4319f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 432091a27b2aSJeff Layton if (IS_ERR(from)) { 432191a27b2aSJeff Layton error = PTR_ERR(from); 43221da177e4SLinus Torvalds goto exit; 432391a27b2aSJeff Layton } 43241da177e4SLinus Torvalds 4325f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4326f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 432791a27b2aSJeff Layton if (IS_ERR(to)) { 432891a27b2aSJeff Layton error = PTR_ERR(to); 43291da177e4SLinus Torvalds goto exit1; 433091a27b2aSJeff Layton } 43311da177e4SLinus Torvalds 43321da177e4SLinus Torvalds error = -EXDEV; 4333f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43341da177e4SLinus Torvalds goto exit2; 43351da177e4SLinus Torvalds 43361da177e4SLinus Torvalds error = -EBUSY; 4337f5beed75SAl Viro if (old_type != LAST_NORM) 43381da177e4SLinus Torvalds goto exit2; 43391da177e4SLinus Torvalds 43400a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43410a7c3937SMiklos Szeredi error = -EEXIST; 4342f5beed75SAl Viro if (new_type != LAST_NORM) 43431da177e4SLinus Torvalds goto exit2; 43441da177e4SLinus Torvalds 4345f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4346c30dabfeSJan Kara if (error) 4347c30dabfeSJan Kara goto exit2; 4348c30dabfeSJan Kara 43498e6d782cSJ. Bruce Fields retry_deleg: 4350f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43511da177e4SLinus Torvalds 4352f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43531da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43541da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43551da177e4SLinus Torvalds goto exit3; 43561da177e4SLinus Torvalds /* source must exist */ 43571da177e4SLinus Torvalds error = -ENOENT; 4358b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43591da177e4SLinus Torvalds goto exit4; 4360f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43611da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43621da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43631da177e4SLinus Torvalds goto exit4; 43640a7c3937SMiklos Szeredi error = -EEXIST; 43650a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43660a7c3937SMiklos Szeredi goto exit5; 4367da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4368da1ce067SMiklos Szeredi error = -ENOENT; 4369da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4370da1ce067SMiklos Szeredi goto exit5; 4371da1ce067SMiklos Szeredi 4372da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4373da1ce067SMiklos Szeredi error = -ENOTDIR; 4374f5beed75SAl Viro if (new_last.name[new_last.len]) 4375da1ce067SMiklos Szeredi goto exit5; 4376da1ce067SMiklos Szeredi } 4377da1ce067SMiklos Szeredi } 43780a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43790a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43800a7c3937SMiklos Szeredi error = -ENOTDIR; 4381f5beed75SAl Viro if (old_last.name[old_last.len]) 43820a7c3937SMiklos Szeredi goto exit5; 4383f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43840a7c3937SMiklos Szeredi goto exit5; 43850a7c3937SMiklos Szeredi } 43860a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43870a7c3937SMiklos Szeredi error = -EINVAL; 43880a7c3937SMiklos Szeredi if (old_dentry == trap) 43890a7c3937SMiklos Szeredi goto exit5; 43901da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4391da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43921da177e4SLinus Torvalds error = -ENOTEMPTY; 43931da177e4SLinus Torvalds if (new_dentry == trap) 43941da177e4SLinus Torvalds goto exit5; 43951da177e4SLinus Torvalds 4396f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4397f5beed75SAl Viro &new_path, new_dentry, flags); 4398be6d3e56SKentaro Takeda if (error) 4399c30dabfeSJan Kara goto exit5; 4400f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4401f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4402520c8b16SMiklos Szeredi &delegated_inode, flags); 44031da177e4SLinus Torvalds exit5: 44041da177e4SLinus Torvalds dput(new_dentry); 44051da177e4SLinus Torvalds exit4: 44061da177e4SLinus Torvalds dput(old_dentry); 44071da177e4SLinus Torvalds exit3: 4408f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44098e6d782cSJ. Bruce Fields if (delegated_inode) { 44108e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44118e6d782cSJ. Bruce Fields if (!error) 44128e6d782cSJ. Bruce Fields goto retry_deleg; 44138e6d782cSJ. Bruce Fields } 4414f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44151da177e4SLinus Torvalds exit2: 4416c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4417c6a94284SJeff Layton should_retry = true; 4418f5beed75SAl Viro path_put(&new_path); 44192ad94ae6SAl Viro putname(to); 44201da177e4SLinus Torvalds exit1: 4421f5beed75SAl Viro path_put(&old_path); 44221da177e4SLinus Torvalds putname(from); 4423c6a94284SJeff Layton if (should_retry) { 4424c6a94284SJeff Layton should_retry = false; 4425c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4426c6a94284SJeff Layton goto retry; 4427c6a94284SJeff Layton } 44282ad94ae6SAl Viro exit: 44291da177e4SLinus Torvalds return error; 44301da177e4SLinus Torvalds } 44311da177e4SLinus Torvalds 4432520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4433520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4434520c8b16SMiklos Szeredi { 4435520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4436520c8b16SMiklos Szeredi } 4437520c8b16SMiklos Szeredi 4438a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44395590ff0dSUlrich Drepper { 4440520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44415590ff0dSUlrich Drepper } 44425590ff0dSUlrich Drepper 4443787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4444787fb6bcSMiklos Szeredi { 4445787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4446787fb6bcSMiklos Szeredi if (error) 4447787fb6bcSMiklos Szeredi return error; 4448787fb6bcSMiklos Szeredi 4449787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4450787fb6bcSMiklos Szeredi return -EPERM; 4451787fb6bcSMiklos Szeredi 4452787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4453787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4454787fb6bcSMiklos Szeredi } 4455787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4456787fb6bcSMiklos Szeredi 44575d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44581da177e4SLinus Torvalds { 44595d826c84SAl Viro int len = PTR_ERR(link); 44601da177e4SLinus Torvalds if (IS_ERR(link)) 44611da177e4SLinus Torvalds goto out; 44621da177e4SLinus Torvalds 44631da177e4SLinus Torvalds len = strlen(link); 44641da177e4SLinus Torvalds if (len > (unsigned) buflen) 44651da177e4SLinus Torvalds len = buflen; 44661da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44671da177e4SLinus Torvalds len = -EFAULT; 44681da177e4SLinus Torvalds out: 44691da177e4SLinus Torvalds return len; 44701da177e4SLinus Torvalds } 44715d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44721da177e4SLinus Torvalds 44731da177e4SLinus Torvalds /* 44741da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44751da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44761da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44771da177e4SLinus Torvalds */ 44781da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44791da177e4SLinus Torvalds { 4480cc314eefSLinus Torvalds void *cookie; 4481d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4482694a1764SMarcin Slusarz int res; 4483cc314eefSLinus Torvalds 4484d4dee48bSAl Viro if (!link) { 4485d4dee48bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); 4486680baacbSAl Viro if (IS_ERR(link)) 4487680baacbSAl Viro return PTR_ERR(link); 4488d4dee48bSAl Viro } 4489680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4490680baacbSAl Viro if (cookie && dentry->d_inode->i_op->put_link) 4491680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4492694a1764SMarcin Slusarz return res; 44931da177e4SLinus Torvalds } 44944d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44951da177e4SLinus Torvalds 44961da177e4SLinus Torvalds /* get the link contents into pagecache */ 44971da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44981da177e4SLinus Torvalds { 4499ebd09abbSDuane Griffin char *kaddr; 45001da177e4SLinus Torvalds struct page *page; 45011da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4502090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 45031da177e4SLinus Torvalds if (IS_ERR(page)) 45046fe6900eSNick Piggin return (char*)page; 45051da177e4SLinus Torvalds *ppage = page; 4506ebd09abbSDuane Griffin kaddr = kmap(page); 4507ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4508ebd09abbSDuane Griffin return kaddr; 45091da177e4SLinus Torvalds } 45101da177e4SLinus Torvalds 45111da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 45121da177e4SLinus Torvalds { 45131da177e4SLinus Torvalds struct page *page = NULL; 45145d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 45151da177e4SLinus Torvalds if (page) { 45161da177e4SLinus Torvalds kunmap(page); 45171da177e4SLinus Torvalds page_cache_release(page); 45181da177e4SLinus Torvalds } 45191da177e4SLinus Torvalds return res; 45201da177e4SLinus Torvalds } 45214d359507SAl Viro EXPORT_SYMBOL(page_readlink); 45221da177e4SLinus Torvalds 4523680baacbSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) 45241da177e4SLinus Torvalds { 4525cc314eefSLinus Torvalds struct page *page = NULL; 4526680baacbSAl Viro char *res = page_getlink(dentry, &page); 4527680baacbSAl Viro if (!IS_ERR(res)) 4528680baacbSAl Viro *cookie = page; 4529680baacbSAl Viro return res; 45301da177e4SLinus Torvalds } 45314d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45321da177e4SLinus Torvalds 4533680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45341da177e4SLinus Torvalds { 4535cc314eefSLinus Torvalds struct page *page = cookie; 45361da177e4SLinus Torvalds kunmap(page); 45371da177e4SLinus Torvalds page_cache_release(page); 45381da177e4SLinus Torvalds } 45394d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45401da177e4SLinus Torvalds 454154566b2cSNick Piggin /* 454254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 454354566b2cSNick Piggin */ 454454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45451da177e4SLinus Torvalds { 45461da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45470adb25d2SKirill Korotaev struct page *page; 4548afddba49SNick Piggin void *fsdata; 4549beb497abSDmitriy Monakhov int err; 45501da177e4SLinus Torvalds char *kaddr; 455154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 455254566b2cSNick Piggin if (nofs) 455354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45541da177e4SLinus Torvalds 45557e53cac4SNeilBrown retry: 4556afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 455754566b2cSNick Piggin flags, &page, &fsdata); 45581da177e4SLinus Torvalds if (err) 4559afddba49SNick Piggin goto fail; 4560afddba49SNick Piggin 4561e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45621da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4563e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4564afddba49SNick Piggin 4565afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4566afddba49SNick Piggin page, fsdata); 45671da177e4SLinus Torvalds if (err < 0) 45681da177e4SLinus Torvalds goto fail; 4569afddba49SNick Piggin if (err < len-1) 4570afddba49SNick Piggin goto retry; 4571afddba49SNick Piggin 45721da177e4SLinus Torvalds mark_inode_dirty(inode); 45731da177e4SLinus Torvalds return 0; 45741da177e4SLinus Torvalds fail: 45751da177e4SLinus Torvalds return err; 45761da177e4SLinus Torvalds } 45774d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45781da177e4SLinus Torvalds 45790adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45800adb25d2SKirill Korotaev { 45810adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 458254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45830adb25d2SKirill Korotaev } 45844d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45850adb25d2SKirill Korotaev 458692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45871da177e4SLinus Torvalds .readlink = generic_readlink, 45881da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45891da177e4SLinus Torvalds .put_link = page_put_link, 45901da177e4SLinus Torvalds }; 45911da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4592