11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 495894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4961f55a6ecSAl Viro struct nameidata { 4971f55a6ecSAl Viro struct path path; 4981f55a6ecSAl Viro struct qstr last; 4991f55a6ecSAl Viro struct path root; 5001f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5011f55a6ecSAl Viro unsigned int flags; 5021f55a6ecSAl Viro unsigned seq, m_seq; 5031f55a6ecSAl Viro int last_type; 5041f55a6ecSAl Viro unsigned depth; 505756daf26SNeilBrown int total_link_count; 506697fc6caSAl Viro struct saved { 507697fc6caSAl Viro struct path link; 508697fc6caSAl Viro void *cookie; 509697fc6caSAl Viro const char *name; 510894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5111f55a6ecSAl Viro }; 5121f55a6ecSAl Viro 513756daf26SNeilBrown static struct nameidata *set_nameidata(struct nameidata *p) 514894bc8c4SAl Viro { 515756daf26SNeilBrown struct nameidata *old = current->nameidata; 516756daf26SNeilBrown p->stack = p->internal; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 518756daf26SNeilBrown current->nameidata = p; 519756daf26SNeilBrown return old; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 522756daf26SNeilBrown static void restore_nameidata(struct nameidata *old) 523894bc8c4SAl Viro { 524756daf26SNeilBrown struct nameidata *now = current->nameidata; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529756daf26SNeilBrown if (now->stack != now->internal) { 530756daf26SNeilBrown kfree(now->stack); 531756daf26SNeilBrown now->stack = now->internal; 532894bc8c4SAl Viro } 533894bc8c4SAl Viro } 534894bc8c4SAl Viro 535894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 536894bc8c4SAl Viro { 537e269f2a7SAl Viro struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved), 538894bc8c4SAl Viro GFP_KERNEL); 539894bc8c4SAl Viro if (unlikely(!p)) 540894bc8c4SAl Viro return -ENOMEM; 541894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 542894bc8c4SAl Viro nd->stack = p; 543894bc8c4SAl Viro return 0; 544894bc8c4SAl Viro } 545894bc8c4SAl Viro 546894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 547894bc8c4SAl Viro { 548da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 551894bc8c4SAl Viro return 0; 552894bc8c4SAl Viro return __nd_alloc_stack(nd); 553894bc8c4SAl Viro } 554894bc8c4SAl Viro 55519660af7SAl Viro /* 55631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 55719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 55819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 55919660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 56019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 56119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 56219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 56319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 56431e6b01fSNick Piggin */ 56531e6b01fSNick Piggin 56631e6b01fSNick Piggin /** 56719660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 56819660af7SAl Viro * @nd: nameidata pathwalk data 56919660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 57039191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 57131e6b01fSNick Piggin * 57219660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 57319660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 57419660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 57531e6b01fSNick Piggin */ 57619660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 57731e6b01fSNick Piggin { 57831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 57931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 58031e6b01fSNick Piggin 58131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 582e5c832d5SLinus Torvalds 583e5c832d5SLinus Torvalds /* 58448a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 58548a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 58648a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 58748a066e7SAl Viro * before returning. Do vfsmount first; if dentry 58848a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 58948a066e7SAl Viro * and rely on dput(NULL) being a no-op. 590e5c832d5SLinus Torvalds */ 59148a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 592e5c832d5SLinus Torvalds return -ECHILD; 593e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 59415570086SLinus Torvalds 59548a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 59648a066e7SAl Viro nd->path.dentry = NULL; 597d870b4a1SAl Viro goto out; 59848a066e7SAl Viro } 59948a066e7SAl Viro 60015570086SLinus Torvalds /* 60115570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 60215570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 60315570086SLinus Torvalds * 60415570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 60515570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 60615570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 60715570086SLinus Torvalds * since we checked the sequence number of the parent after we got 60815570086SLinus Torvalds * the child sequence number. So we know the parent must still 60915570086SLinus Torvalds * be valid if the child sequence number is still valid. 61015570086SLinus Torvalds */ 61119660af7SAl Viro if (!dentry) { 612e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 613e5c832d5SLinus Torvalds goto out; 61419660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 61519660af7SAl Viro } else { 616e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 617e5c832d5SLinus Torvalds goto out; 618e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 619e5c832d5SLinus Torvalds goto drop_dentry; 62019660af7SAl Viro } 621e5c832d5SLinus Torvalds 622e5c832d5SLinus Torvalds /* 623e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 624e5c832d5SLinus Torvalds * still valid and get it if required. 625e5c832d5SLinus Torvalds */ 626e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 627e5c832d5SLinus Torvalds spin_lock(&fs->lock); 628e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 629e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 63031e6b01fSNick Piggin path_get(&nd->root); 63131e6b01fSNick Piggin spin_unlock(&fs->lock); 63231e6b01fSNick Piggin } 63331e6b01fSNick Piggin 6348b61e74fSAl Viro rcu_read_unlock(); 63531e6b01fSNick Piggin return 0; 63619660af7SAl Viro 637e5c832d5SLinus Torvalds unlock_and_drop_dentry: 63831e6b01fSNick Piggin spin_unlock(&fs->lock); 639e5c832d5SLinus Torvalds drop_dentry: 6408b61e74fSAl Viro rcu_read_unlock(); 641e5c832d5SLinus Torvalds dput(dentry); 642d0d27277SLinus Torvalds goto drop_root_mnt; 643e5c832d5SLinus Torvalds out: 6448b61e74fSAl Viro rcu_read_unlock(); 645d0d27277SLinus Torvalds drop_root_mnt: 646d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 647d0d27277SLinus Torvalds nd->root.mnt = NULL; 64831e6b01fSNick Piggin return -ECHILD; 64931e6b01fSNick Piggin } 65031e6b01fSNick Piggin 6514ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 65234286d66SNick Piggin { 6534ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 65434286d66SNick Piggin } 65534286d66SNick Piggin 6569f1fafeeSAl Viro /** 6579f1fafeeSAl Viro * complete_walk - successful completion of path walk 6589f1fafeeSAl Viro * @nd: pointer nameidata 65939159de2SJeff Layton * 6609f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6619f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6629f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6639f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6649f1fafeeSAl Viro * need to drop nd->path. 66539159de2SJeff Layton */ 6669f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 66739159de2SJeff Layton { 66816c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 66939159de2SJeff Layton int status; 67039159de2SJeff Layton 6719f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6729f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6739f1fafeeSAl Viro nd->root.mnt = NULL; 674deb106c6SAl Viro if (unlikely(unlazy_walk(nd, NULL))) 67548a066e7SAl Viro return -ECHILD; 67648a066e7SAl Viro } 6779f1fafeeSAl Viro 67816c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 67939159de2SJeff Layton return 0; 68039159de2SJeff Layton 681ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 68216c2cd71SAl Viro return 0; 68316c2cd71SAl Viro 684ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 68539159de2SJeff Layton if (status > 0) 68639159de2SJeff Layton return 0; 68739159de2SJeff Layton 68816c2cd71SAl Viro if (!status) 68939159de2SJeff Layton status = -ESTALE; 69016c2cd71SAl Viro 69139159de2SJeff Layton return status; 69239159de2SJeff Layton } 69339159de2SJeff Layton 6942a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6952a737871SAl Viro { 696f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6972a737871SAl Viro } 6982a737871SAl Viro 6997bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 70031e6b01fSNick Piggin { 70131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 7027bd88377SAl Viro unsigned seq, res; 703c28cc364SNick Piggin 704c28cc364SNick Piggin do { 705c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 70631e6b01fSNick Piggin nd->root = fs->root; 7077bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 708c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 7097bd88377SAl Viro return res; 71031e6b01fSNick Piggin } 71131e6b01fSNick Piggin 7121d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 713051d3812SIan Kent { 714051d3812SIan Kent dput(path->dentry); 7154ac91378SJan Blunck if (path->mnt != nd->path.mnt) 716051d3812SIan Kent mntput(path->mnt); 717051d3812SIan Kent } 718051d3812SIan Kent 7197b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 7207b9337aaSNick Piggin struct nameidata *nd) 721051d3812SIan Kent { 72231e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 7234ac91378SJan Blunck dput(nd->path.dentry); 72431e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 7254ac91378SJan Blunck mntput(nd->path.mnt); 7269a229683SHuang Shijie } 72731e6b01fSNick Piggin nd->path.mnt = path->mnt; 7284ac91378SJan Blunck nd->path.dentry = path->dentry; 729051d3812SIan Kent } 730051d3812SIan Kent 731b5fb63c1SChristoph Hellwig /* 732b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 733b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 734b5fb63c1SChristoph Hellwig */ 7356e77137bSAl Viro void nd_jump_link(struct path *path) 736b5fb63c1SChristoph Hellwig { 7376e77137bSAl Viro struct nameidata *nd = current->nameidata; 738b5fb63c1SChristoph Hellwig path_put(&nd->path); 739b5fb63c1SChristoph Hellwig 740b5fb63c1SChristoph Hellwig nd->path = *path; 741b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 742b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 743b5fb63c1SChristoph Hellwig } 744b5fb63c1SChristoph Hellwig 745b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 746574197e0SAl Viro { 74721c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 748b9ff4429SAl Viro struct inode *inode = last->link.dentry->d_inode; 749b9ff4429SAl Viro if (last->cookie && inode->i_op->put_link) 750b9ff4429SAl Viro inode->i_op->put_link(last->link.dentry, last->cookie); 751b9ff4429SAl Viro path_put(&last->link); 752574197e0SAl Viro } 753574197e0SAl Viro 754561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 755561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 756800179c9SKees Cook 757800179c9SKees Cook /** 758800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 75955852635SRandy Dunlap * @nd: nameidata pathwalk data 760800179c9SKees Cook * 761800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 762800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 763800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 764800179c9SKees Cook * processes from failing races against path names that may change out 765800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 766800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 767800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 768800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 769800179c9SKees Cook * 770800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 771800179c9SKees Cook */ 772fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 773800179c9SKees Cook { 774800179c9SKees Cook const struct inode *inode; 775800179c9SKees Cook const struct inode *parent; 776800179c9SKees Cook 777800179c9SKees Cook if (!sysctl_protected_symlinks) 778800179c9SKees Cook return 0; 779800179c9SKees Cook 780800179c9SKees Cook /* Allowed if owner and follower match. */ 7811cf2665bSAl Viro inode = nd->stack[0].link.dentry->d_inode; 78281abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 783800179c9SKees Cook return 0; 784800179c9SKees Cook 785800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 786800179c9SKees Cook parent = nd->path.dentry->d_inode; 787800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 788800179c9SKees Cook return 0; 789800179c9SKees Cook 790800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 79181abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 792800179c9SKees Cook return 0; 793800179c9SKees Cook 7941cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 795800179c9SKees Cook return -EACCES; 796800179c9SKees Cook } 797800179c9SKees Cook 798800179c9SKees Cook /** 799800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 800800179c9SKees Cook * @inode: the source inode to hardlink from 801800179c9SKees Cook * 802800179c9SKees Cook * Return false if at least one of the following conditions: 803800179c9SKees Cook * - inode is not a regular file 804800179c9SKees Cook * - inode is setuid 805800179c9SKees Cook * - inode is setgid and group-exec 806800179c9SKees Cook * - access failure for read and write 807800179c9SKees Cook * 808800179c9SKees Cook * Otherwise returns true. 809800179c9SKees Cook */ 810800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 811800179c9SKees Cook { 812800179c9SKees Cook umode_t mode = inode->i_mode; 813800179c9SKees Cook 814800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 815800179c9SKees Cook if (!S_ISREG(mode)) 816800179c9SKees Cook return false; 817800179c9SKees Cook 818800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 819800179c9SKees Cook if (mode & S_ISUID) 820800179c9SKees Cook return false; 821800179c9SKees Cook 822800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 823800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 824800179c9SKees Cook return false; 825800179c9SKees Cook 826800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 827800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 828800179c9SKees Cook return false; 829800179c9SKees Cook 830800179c9SKees Cook return true; 831800179c9SKees Cook } 832800179c9SKees Cook 833800179c9SKees Cook /** 834800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 835800179c9SKees Cook * @link: the source to hardlink from 836800179c9SKees Cook * 837800179c9SKees Cook * Block hardlink when all of: 838800179c9SKees Cook * - sysctl_protected_hardlinks enabled 839800179c9SKees Cook * - fsuid does not match inode 840800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 841800179c9SKees Cook * - not CAP_FOWNER 842800179c9SKees Cook * 843800179c9SKees Cook * Returns 0 if successful, -ve on error. 844800179c9SKees Cook */ 845800179c9SKees Cook static int may_linkat(struct path *link) 846800179c9SKees Cook { 847800179c9SKees Cook const struct cred *cred; 848800179c9SKees Cook struct inode *inode; 849800179c9SKees Cook 850800179c9SKees Cook if (!sysctl_protected_hardlinks) 851800179c9SKees Cook return 0; 852800179c9SKees Cook 853800179c9SKees Cook cred = current_cred(); 854800179c9SKees Cook inode = link->dentry->d_inode; 855800179c9SKees Cook 856800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 857800179c9SKees Cook * otherwise, it must be a safe source. 858800179c9SKees Cook */ 85981abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 860800179c9SKees Cook capable(CAP_FOWNER)) 861800179c9SKees Cook return 0; 862800179c9SKees Cook 863a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 864800179c9SKees Cook return -EPERM; 865800179c9SKees Cook } 866800179c9SKees Cook 8673b2e7f75SAl Viro static __always_inline 8683b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 8691da177e4SLinus Torvalds { 870ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 8711cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 8720a959df5SAl Viro struct inode *inode = dentry->d_inode; 8736d7b5aaeSAl Viro int error; 8740a959df5SAl Viro const char *res; 8751da177e4SLinus Torvalds 876844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 877844a3917SAl Viro 878574197e0SAl Viro cond_resched(); 879574197e0SAl Viro 8803b2e7f75SAl Viro touch_atime(&last->link); 881cd4e91d3SAl Viro 88237882db0SNeilBrown error = security_inode_follow_link(dentry); 8836d7b5aaeSAl Viro if (error) 8846920a440SAl Viro return ERR_PTR(error); 88536f3b4f6SAl Viro 88686acdca1SAl Viro nd->last_type = LAST_BIND; 887d4dee48bSAl Viro res = inode->i_link; 888d4dee48bSAl Viro if (!res) { 8896e77137bSAl Viro res = inode->i_op->follow_link(dentry, &last->cookie); 890fab51e8aSAl Viro if (IS_ERR_OR_NULL(res)) { 8916920a440SAl Viro last->cookie = NULL; 892fab51e8aSAl Viro return res; 8930a959df5SAl Viro } 894fab51e8aSAl Viro } 895fab51e8aSAl Viro if (*res == '/') { 896fab51e8aSAl Viro if (!nd->root.mnt) 897fab51e8aSAl Viro set_root(nd); 898fab51e8aSAl Viro path_put(&nd->path); 899fab51e8aSAl Viro nd->path = nd->root; 900fab51e8aSAl Viro path_get(&nd->root); 901fab51e8aSAl Viro nd->inode = nd->path.dentry->d_inode; 902fab51e8aSAl Viro nd->flags |= LOOKUP_JUMPED; 903fab51e8aSAl Viro while (unlikely(*++res == '/')) 904fab51e8aSAl Viro ; 905fab51e8aSAl Viro } 906fab51e8aSAl Viro if (!*res) 907fab51e8aSAl Viro res = NULL; 9080a959df5SAl Viro return res; 9090a959df5SAl Viro } 9106d7b5aaeSAl Viro 91131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 91231e6b01fSNick Piggin { 9130714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9140714a533SAl Viro struct mount *parent; 91531e6b01fSNick Piggin struct dentry *mountpoint; 91631e6b01fSNick Piggin 9170714a533SAl Viro parent = mnt->mnt_parent; 9180714a533SAl Viro if (&parent->mnt == path->mnt) 91931e6b01fSNick Piggin return 0; 920a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 92131e6b01fSNick Piggin path->dentry = mountpoint; 9220714a533SAl Viro path->mnt = &parent->mnt; 92331e6b01fSNick Piggin return 1; 92431e6b01fSNick Piggin } 92531e6b01fSNick Piggin 926f015f126SDavid Howells /* 927f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 928f015f126SDavid Howells * 929f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 930f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 931f015f126SDavid Howells * Up is towards /. 932f015f126SDavid Howells * 933f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 934f015f126SDavid Howells * root. 935f015f126SDavid Howells */ 936bab77ebfSAl Viro int follow_up(struct path *path) 9371da177e4SLinus Torvalds { 9380714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9390714a533SAl Viro struct mount *parent; 9401da177e4SLinus Torvalds struct dentry *mountpoint; 94199b7db7bSNick Piggin 94248a066e7SAl Viro read_seqlock_excl(&mount_lock); 9430714a533SAl Viro parent = mnt->mnt_parent; 9443c0a6163SAl Viro if (parent == mnt) { 94548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9461da177e4SLinus Torvalds return 0; 9471da177e4SLinus Torvalds } 9480714a533SAl Viro mntget(&parent->mnt); 949a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 95048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 951bab77ebfSAl Viro dput(path->dentry); 952bab77ebfSAl Viro path->dentry = mountpoint; 953bab77ebfSAl Viro mntput(path->mnt); 9540714a533SAl Viro path->mnt = &parent->mnt; 9551da177e4SLinus Torvalds return 1; 9561da177e4SLinus Torvalds } 9574d359507SAl Viro EXPORT_SYMBOL(follow_up); 9581da177e4SLinus Torvalds 959b5c84bf6SNick Piggin /* 9609875cf80SDavid Howells * Perform an automount 9619875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9629875cf80SDavid Howells * were called with. 9631da177e4SLinus Torvalds */ 964756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 9659875cf80SDavid Howells bool *need_mntput) 96631e6b01fSNick Piggin { 9679875cf80SDavid Howells struct vfsmount *mnt; 968ea5b778aSDavid Howells int err; 9699875cf80SDavid Howells 9709875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9719875cf80SDavid Howells return -EREMOTE; 9729875cf80SDavid Howells 9730ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9740ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9750ec26fd0SMiklos Szeredi * the name. 9760ec26fd0SMiklos Szeredi * 9770ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9785a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9790ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9800ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9810ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9820ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9835a30d8a2SDavid Howells */ 984756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 985d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9865a30d8a2SDavid Howells path->dentry->d_inode) 9879875cf80SDavid Howells return -EISDIR; 9880ec26fd0SMiklos Szeredi 989756daf26SNeilBrown nd->total_link_count++; 990756daf26SNeilBrown if (nd->total_link_count >= 40) 9919875cf80SDavid Howells return -ELOOP; 9929875cf80SDavid Howells 9939875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9949875cf80SDavid Howells if (IS_ERR(mnt)) { 9959875cf80SDavid Howells /* 9969875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9979875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9989875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9999875cf80SDavid Howells * 10009875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 10019875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 10029875cf80SDavid Howells * the path is inaccessible and we should say so. 10039875cf80SDavid Howells */ 1004756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 10059875cf80SDavid Howells return -EREMOTE; 10069875cf80SDavid Howells return PTR_ERR(mnt); 100731e6b01fSNick Piggin } 1008ea5b778aSDavid Howells 10099875cf80SDavid Howells if (!mnt) /* mount collision */ 10109875cf80SDavid Howells return 0; 10119875cf80SDavid Howells 10128aef1884SAl Viro if (!*need_mntput) { 10138aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 10148aef1884SAl Viro mntget(path->mnt); 10158aef1884SAl Viro *need_mntput = true; 10168aef1884SAl Viro } 101719a167afSAl Viro err = finish_automount(mnt, path); 1018ea5b778aSDavid Howells 1019ea5b778aSDavid Howells switch (err) { 1020ea5b778aSDavid Howells case -EBUSY: 1021ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 102219a167afSAl Viro return 0; 1023ea5b778aSDavid Howells case 0: 10248aef1884SAl Viro path_put(path); 10259875cf80SDavid Howells path->mnt = mnt; 10269875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 10279875cf80SDavid Howells return 0; 102819a167afSAl Viro default: 102919a167afSAl Viro return err; 10309875cf80SDavid Howells } 103119a167afSAl Viro 1032ea5b778aSDavid Howells } 10339875cf80SDavid Howells 10349875cf80SDavid Howells /* 10359875cf80SDavid Howells * Handle a dentry that is managed in some way. 1036cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10379875cf80SDavid Howells * - Flagged as mountpoint 10389875cf80SDavid Howells * - Flagged as automount point 10399875cf80SDavid Howells * 10409875cf80SDavid Howells * This may only be called in refwalk mode. 10419875cf80SDavid Howells * 10429875cf80SDavid Howells * Serialization is taken care of in namespace.c 10439875cf80SDavid Howells */ 1044756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 10459875cf80SDavid Howells { 10468aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10479875cf80SDavid Howells unsigned managed; 10489875cf80SDavid Howells bool need_mntput = false; 10498aef1884SAl Viro int ret = 0; 10509875cf80SDavid Howells 10519875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10529875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10539875cf80SDavid Howells * the components of that value change under us */ 10549875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10559875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10569875cf80SDavid Howells unlikely(managed != 0)) { 1057cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1058cc53ce53SDavid Howells * being held. */ 1059cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1060cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1061cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10621aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1063cc53ce53SDavid Howells if (ret < 0) 10648aef1884SAl Viro break; 1065cc53ce53SDavid Howells } 1066cc53ce53SDavid Howells 10679875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10689875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10699875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10709875cf80SDavid Howells if (mounted) { 10719875cf80SDavid Howells dput(path->dentry); 10729875cf80SDavid Howells if (need_mntput) 1073463ffb2eSAl Viro mntput(path->mnt); 1074463ffb2eSAl Viro path->mnt = mounted; 1075463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10769875cf80SDavid Howells need_mntput = true; 10779875cf80SDavid Howells continue; 1078463ffb2eSAl Viro } 1079463ffb2eSAl Viro 10809875cf80SDavid Howells /* Something is mounted on this dentry in another 10819875cf80SDavid Howells * namespace and/or whatever was mounted there in this 108248a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 108348a066e7SAl Viro * get it */ 10841da177e4SLinus Torvalds } 10859875cf80SDavid Howells 10869875cf80SDavid Howells /* Handle an automount point */ 10879875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1088756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 10899875cf80SDavid Howells if (ret < 0) 10908aef1884SAl Viro break; 10919875cf80SDavid Howells continue; 10929875cf80SDavid Howells } 10939875cf80SDavid Howells 10949875cf80SDavid Howells /* We didn't change the current path point */ 10959875cf80SDavid Howells break; 10969875cf80SDavid Howells } 10978aef1884SAl Viro 10988aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10998aef1884SAl Viro mntput(path->mnt); 11008aef1884SAl Viro if (ret == -EISDIR) 11018aef1884SAl Viro ret = 0; 11028402752eSAl Viro if (need_mntput) 11038402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 11048402752eSAl Viro if (unlikely(ret < 0)) 11058402752eSAl Viro path_put_conditional(path, nd); 11068402752eSAl Viro return ret; 11071da177e4SLinus Torvalds } 11081da177e4SLinus Torvalds 1109cc53ce53SDavid Howells int follow_down_one(struct path *path) 11101da177e4SLinus Torvalds { 11111da177e4SLinus Torvalds struct vfsmount *mounted; 11121da177e4SLinus Torvalds 11131c755af4SAl Viro mounted = lookup_mnt(path); 11141da177e4SLinus Torvalds if (mounted) { 11159393bd07SAl Viro dput(path->dentry); 11169393bd07SAl Viro mntput(path->mnt); 11179393bd07SAl Viro path->mnt = mounted; 11189393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 11191da177e4SLinus Torvalds return 1; 11201da177e4SLinus Torvalds } 11211da177e4SLinus Torvalds return 0; 11221da177e4SLinus Torvalds } 11234d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 11241da177e4SLinus Torvalds 1125b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 112662a7375eSIan Kent { 1127b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1128b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 112962a7375eSIan Kent } 113062a7375eSIan Kent 11319875cf80SDavid Howells /* 1132287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1133287548e4SAl Viro * we meet a managed dentry that would need blocking. 11349875cf80SDavid Howells */ 11359875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1136287548e4SAl Viro struct inode **inode) 11379875cf80SDavid Howells { 113862a7375eSIan Kent for (;;) { 1139c7105365SAl Viro struct mount *mounted; 114062a7375eSIan Kent /* 114162a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 114262a7375eSIan Kent * that wants to block transit. 114362a7375eSIan Kent */ 1144b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1145b8faf035SNeilBrown case -ECHILD: 1146b8faf035SNeilBrown default: 1147ab90911fSDavid Howells return false; 1148b8faf035SNeilBrown case -EISDIR: 1149b8faf035SNeilBrown return true; 1150b8faf035SNeilBrown case 0: 1151b8faf035SNeilBrown break; 1152b8faf035SNeilBrown } 115362a7375eSIan Kent 115462a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1155b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 115662a7375eSIan Kent 1157474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11589875cf80SDavid Howells if (!mounted) 11599875cf80SDavid Howells break; 1160c7105365SAl Viro path->mnt = &mounted->mnt; 1161c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1162a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11639875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 116459430262SLinus Torvalds /* 116559430262SLinus Torvalds * Update the inode too. We don't need to re-check the 116659430262SLinus Torvalds * dentry sequence number here after this d_inode read, 116759430262SLinus Torvalds * because a mount-point is always pinned. 116859430262SLinus Torvalds */ 116959430262SLinus Torvalds *inode = path->dentry->d_inode; 11709875cf80SDavid Howells } 1171f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1172b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1173287548e4SAl Viro } 1174287548e4SAl Viro 117531e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 117631e6b01fSNick Piggin { 11774023bfc9SAl Viro struct inode *inode = nd->inode; 11787bd88377SAl Viro if (!nd->root.mnt) 117931e6b01fSNick Piggin set_root_rcu(nd); 118031e6b01fSNick Piggin 118131e6b01fSNick Piggin while (1) { 118231e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 118331e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 118431e6b01fSNick Piggin break; 118531e6b01fSNick Piggin } 118631e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 118731e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 118831e6b01fSNick Piggin struct dentry *parent = old->d_parent; 118931e6b01fSNick Piggin unsigned seq; 119031e6b01fSNick Piggin 11914023bfc9SAl Viro inode = parent->d_inode; 119231e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 119331e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1194ef7562d5SAl Viro goto failed; 119531e6b01fSNick Piggin nd->path.dentry = parent; 119631e6b01fSNick Piggin nd->seq = seq; 119731e6b01fSNick Piggin break; 119831e6b01fSNick Piggin } 119931e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 120031e6b01fSNick Piggin break; 12014023bfc9SAl Viro inode = nd->path.dentry->d_inode; 120231e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 120331e6b01fSNick Piggin } 1204b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1205b37199e6SAl Viro struct mount *mounted; 1206b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1207b37199e6SAl Viro if (!mounted) 1208b37199e6SAl Viro break; 1209b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1210b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 12114023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1212b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1213f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1214b37199e6SAl Viro goto failed; 1215b37199e6SAl Viro } 12164023bfc9SAl Viro nd->inode = inode; 121731e6b01fSNick Piggin return 0; 1218ef7562d5SAl Viro 1219ef7562d5SAl Viro failed: 1220ef7562d5SAl Viro return -ECHILD; 122131e6b01fSNick Piggin } 122231e6b01fSNick Piggin 12239875cf80SDavid Howells /* 1224cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1225cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1226cc53ce53SDavid Howells * caller is permitted to proceed or not. 1227cc53ce53SDavid Howells */ 12287cc90cc3SAl Viro int follow_down(struct path *path) 1229cc53ce53SDavid Howells { 1230cc53ce53SDavid Howells unsigned managed; 1231cc53ce53SDavid Howells int ret; 1232cc53ce53SDavid Howells 1233cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1234cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1235cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1236cc53ce53SDavid Howells * being held. 1237cc53ce53SDavid Howells * 1238cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1239cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1240cc53ce53SDavid Howells * other than its daemon the right to mount on its 1241cc53ce53SDavid Howells * superstructure. 1242cc53ce53SDavid Howells * 1243cc53ce53SDavid Howells * The filesystem may sleep at this point. 1244cc53ce53SDavid Howells */ 1245cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1246cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1247cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1248ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12491aed3e42SAl Viro path->dentry, false); 1250cc53ce53SDavid Howells if (ret < 0) 1251cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1252cc53ce53SDavid Howells } 1253cc53ce53SDavid Howells 1254cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1255cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1256cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1257cc53ce53SDavid Howells if (!mounted) 1258cc53ce53SDavid Howells break; 1259cc53ce53SDavid Howells dput(path->dentry); 1260cc53ce53SDavid Howells mntput(path->mnt); 1261cc53ce53SDavid Howells path->mnt = mounted; 1262cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1263cc53ce53SDavid Howells continue; 1264cc53ce53SDavid Howells } 1265cc53ce53SDavid Howells 1266cc53ce53SDavid Howells /* Don't handle automount points here */ 1267cc53ce53SDavid Howells break; 1268cc53ce53SDavid Howells } 1269cc53ce53SDavid Howells return 0; 1270cc53ce53SDavid Howells } 12714d359507SAl Viro EXPORT_SYMBOL(follow_down); 1272cc53ce53SDavid Howells 1273cc53ce53SDavid Howells /* 12749875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12759875cf80SDavid Howells */ 12769875cf80SDavid Howells static void follow_mount(struct path *path) 12779875cf80SDavid Howells { 12789875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12799875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12809875cf80SDavid Howells if (!mounted) 12819875cf80SDavid Howells break; 12829875cf80SDavid Howells dput(path->dentry); 12839875cf80SDavid Howells mntput(path->mnt); 12849875cf80SDavid Howells path->mnt = mounted; 12859875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12869875cf80SDavid Howells } 12879875cf80SDavid Howells } 12889875cf80SDavid Howells 128931e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12901da177e4SLinus Torvalds { 12917bd88377SAl Viro if (!nd->root.mnt) 12922a737871SAl Viro set_root(nd); 1293e518ddb7SAndreas Mohr 12941da177e4SLinus Torvalds while(1) { 12954ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12961da177e4SLinus Torvalds 12972a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12982a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12991da177e4SLinus Torvalds break; 13001da177e4SLinus Torvalds } 13014ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 13023088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 13033088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 13041da177e4SLinus Torvalds dput(old); 13051da177e4SLinus Torvalds break; 13061da177e4SLinus Torvalds } 13073088dd70SAl Viro if (!follow_up(&nd->path)) 13081da177e4SLinus Torvalds break; 13091da177e4SLinus Torvalds } 131079ed0226SAl Viro follow_mount(&nd->path); 131131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 13121da177e4SLinus Torvalds } 13131da177e4SLinus Torvalds 13141da177e4SLinus Torvalds /* 1315bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1316bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1317bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1318bad61189SMiklos Szeredi * 1319bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1320baa03890SNick Piggin */ 1321bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1322201f956eSAl Viro unsigned int flags, bool *need_lookup) 1323baa03890SNick Piggin { 1324baa03890SNick Piggin struct dentry *dentry; 1325bad61189SMiklos Szeredi int error; 1326baa03890SNick Piggin 1327bad61189SMiklos Szeredi *need_lookup = false; 1328bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1329bad61189SMiklos Szeredi if (dentry) { 133039e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1331201f956eSAl Viro error = d_revalidate(dentry, flags); 1332bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1333bad61189SMiklos Szeredi if (error < 0) { 1334bad61189SMiklos Szeredi dput(dentry); 1335bad61189SMiklos Szeredi return ERR_PTR(error); 13365542aa2fSEric W. Biederman } else { 13375542aa2fSEric W. Biederman d_invalidate(dentry); 1338bad61189SMiklos Szeredi dput(dentry); 1339bad61189SMiklos Szeredi dentry = NULL; 1340bad61189SMiklos Szeredi } 1341bad61189SMiklos Szeredi } 1342bad61189SMiklos Szeredi } 1343bad61189SMiklos Szeredi } 1344baa03890SNick Piggin 1345bad61189SMiklos Szeredi if (!dentry) { 1346bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1347baa03890SNick Piggin if (unlikely(!dentry)) 1348baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1349baa03890SNick Piggin 1350bad61189SMiklos Szeredi *need_lookup = true; 1351baa03890SNick Piggin } 1352baa03890SNick Piggin return dentry; 1353baa03890SNick Piggin } 1354baa03890SNick Piggin 1355baa03890SNick Piggin /* 135613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 135713a2c3beSJ. Bruce Fields * unhashed. 1358bad61189SMiklos Szeredi * 1359bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 136044396f4bSJosef Bacik */ 1361bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 136272bd866aSAl Viro unsigned int flags) 136344396f4bSJosef Bacik { 136444396f4bSJosef Bacik struct dentry *old; 136544396f4bSJosef Bacik 136644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1367bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1368e188dc02SMiklos Szeredi dput(dentry); 136944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1370e188dc02SMiklos Szeredi } 137144396f4bSJosef Bacik 137272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 137344396f4bSJosef Bacik if (unlikely(old)) { 137444396f4bSJosef Bacik dput(dentry); 137544396f4bSJosef Bacik dentry = old; 137644396f4bSJosef Bacik } 137744396f4bSJosef Bacik return dentry; 137844396f4bSJosef Bacik } 137944396f4bSJosef Bacik 1380a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 138172bd866aSAl Viro struct dentry *base, unsigned int flags) 1382a3255546SAl Viro { 1383bad61189SMiklos Szeredi bool need_lookup; 1384a3255546SAl Viro struct dentry *dentry; 1385a3255546SAl Viro 138672bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1387bad61189SMiklos Szeredi if (!need_lookup) 1388a3255546SAl Viro return dentry; 1389bad61189SMiklos Szeredi 139072bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1391a3255546SAl Viro } 1392a3255546SAl Viro 139344396f4bSJosef Bacik /* 13941da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13951da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13961da177e4SLinus Torvalds * It _is_ time-critical. 13971da177e4SLinus Torvalds */ 1398e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 139931e6b01fSNick Piggin struct path *path, struct inode **inode) 14001da177e4SLinus Torvalds { 14014ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 140231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14035a18fff2SAl Viro int need_reval = 1; 14045a18fff2SAl Viro int status = 1; 14059875cf80SDavid Howells int err; 14069875cf80SDavid Howells 14073cac260aSAl Viro /* 1408b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1409b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1410b04f784eSNick Piggin * do the non-racy lookup, below. 1411b04f784eSNick Piggin */ 141231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 141331e6b01fSNick Piggin unsigned seq; 1414766c4cbfSAl Viro bool negative; 1415da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14165a18fff2SAl Viro if (!dentry) 14175a18fff2SAl Viro goto unlazy; 14185a18fff2SAl Viro 141912f8ad4bSLinus Torvalds /* 142012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 142112f8ad4bSLinus Torvalds * the dentry name information from lookup. 142212f8ad4bSLinus Torvalds */ 142312f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1424766c4cbfSAl Viro negative = d_is_negative(dentry); 142512f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 142612f8ad4bSLinus Torvalds return -ECHILD; 1427766c4cbfSAl Viro if (negative) 1428766c4cbfSAl Viro return -ENOENT; 142912f8ad4bSLinus Torvalds 143012f8ad4bSLinus Torvalds /* 143112f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 143212f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 143312f8ad4bSLinus Torvalds * 143412f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 143512f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 143612f8ad4bSLinus Torvalds */ 143731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 143831e6b01fSNick Piggin return -ECHILD; 143931e6b01fSNick Piggin nd->seq = seq; 14405a18fff2SAl Viro 144124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14424ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14435a18fff2SAl Viro if (unlikely(status <= 0)) { 14445a18fff2SAl Viro if (status != -ECHILD) 14455a18fff2SAl Viro need_reval = 0; 14465a18fff2SAl Viro goto unlazy; 14475a18fff2SAl Viro } 144824643087SAl Viro } 144931e6b01fSNick Piggin path->mnt = mnt; 145031e6b01fSNick Piggin path->dentry = dentry; 1451b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14529875cf80SDavid Howells return 0; 14535a18fff2SAl Viro unlazy: 145419660af7SAl Viro if (unlazy_walk(nd, dentry)) 14555a18fff2SAl Viro return -ECHILD; 14565a18fff2SAl Viro } else { 1457e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 145824643087SAl Viro } 14595a18fff2SAl Viro 146081e6f520SAl Viro if (unlikely(!dentry)) 146181e6f520SAl Viro goto need_lookup; 14625a18fff2SAl Viro 14635a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14644ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14655a18fff2SAl Viro if (unlikely(status <= 0)) { 14665a18fff2SAl Viro if (status < 0) { 14675a18fff2SAl Viro dput(dentry); 14685a18fff2SAl Viro return status; 14695a18fff2SAl Viro } 14705542aa2fSEric W. Biederman d_invalidate(dentry); 14715a18fff2SAl Viro dput(dentry); 147281e6f520SAl Viro goto need_lookup; 14735a18fff2SAl Viro } 1474697f514dSMiklos Szeredi 1475766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1476766c4cbfSAl Viro dput(dentry); 1477766c4cbfSAl Viro return -ENOENT; 1478766c4cbfSAl Viro } 14791da177e4SLinus Torvalds path->mnt = mnt; 14801da177e4SLinus Torvalds path->dentry = dentry; 1481756daf26SNeilBrown err = follow_managed(path, nd); 14828402752eSAl Viro if (likely(!err)) 148331e6b01fSNick Piggin *inode = path->dentry->d_inode; 14848402752eSAl Viro return err; 148581e6f520SAl Viro 148681e6f520SAl Viro need_lookup: 1487697f514dSMiklos Szeredi return 1; 1488697f514dSMiklos Szeredi } 1489697f514dSMiklos Szeredi 1490697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1491cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1492697f514dSMiklos Szeredi { 1493697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1494697f514dSMiklos Szeredi 1495697f514dSMiklos Szeredi parent = nd->path.dentry; 149681e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 149781e6f520SAl Viro 149881e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1499cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 150081e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 150181e6f520SAl Viro if (IS_ERR(dentry)) 150281e6f520SAl Viro return PTR_ERR(dentry); 1503697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1504697f514dSMiklos Szeredi path->dentry = dentry; 15058402752eSAl Viro return follow_managed(path, nd); 15061da177e4SLinus Torvalds } 15071da177e4SLinus Torvalds 150852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 150952094c8aSAl Viro { 151052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15114ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 151252094c8aSAl Viro if (err != -ECHILD) 151352094c8aSAl Viro return err; 151419660af7SAl Viro if (unlazy_walk(nd, NULL)) 151552094c8aSAl Viro return -ECHILD; 151652094c8aSAl Viro } 15174ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 151852094c8aSAl Viro } 151952094c8aSAl Viro 15209856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15219856fa1bSAl Viro { 15229856fa1bSAl Viro if (type == LAST_DOTDOT) { 15239856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 152470291aecSAl Viro return follow_dotdot_rcu(nd); 15259856fa1bSAl Viro } else 15269856fa1bSAl Viro follow_dotdot(nd); 15279856fa1bSAl Viro } 15289856fa1bSAl Viro return 0; 15299856fa1bSAl Viro } 15309856fa1bSAl Viro 1531951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1532951361f9SAl Viro { 1533951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1534951361f9SAl Viro path_put(&nd->path); 1535951361f9SAl Viro } else { 1536951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15375b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1538951361f9SAl Viro nd->root.mnt = NULL; 15398b61e74fSAl Viro rcu_read_unlock(); 1540951361f9SAl Viro } 154115439726SAl Viro while (unlikely(nd->depth)) 154215439726SAl Viro put_link(nd); 1543951361f9SAl Viro } 1544951361f9SAl Viro 1545d63ff28fSAl Viro static int pick_link(struct nameidata *nd, struct path *link) 1546d63ff28fSAl Viro { 1547626de996SAl Viro int error; 15481cf2665bSAl Viro struct saved *last; 1549756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1550626de996SAl Viro path_to_nameidata(link, nd); 1551626de996SAl Viro return -ELOOP; 1552626de996SAl Viro } 1553d63ff28fSAl Viro if (nd->flags & LOOKUP_RCU) { 1554d63ff28fSAl Viro if (unlikely(nd->path.mnt != link->mnt || 1555d63ff28fSAl Viro unlazy_walk(nd, link->dentry))) { 1556d63ff28fSAl Viro return -ECHILD; 1557d63ff28fSAl Viro } 1558d63ff28fSAl Viro } 1559cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1560cd179f44SAl Viro mntget(link->mnt); 1561626de996SAl Viro error = nd_alloc_stack(nd); 1562626de996SAl Viro if (unlikely(error)) { 1563cd179f44SAl Viro path_put(link); 1564626de996SAl Viro return error; 1565626de996SAl Viro } 1566626de996SAl Viro 1567ab104923SAl Viro last = nd->stack + nd->depth++; 15681cf2665bSAl Viro last->link = *link; 1569ab104923SAl Viro last->cookie = NULL; 1570d63ff28fSAl Viro return 1; 1571d63ff28fSAl Viro } 1572d63ff28fSAl Viro 15733ddcd056SLinus Torvalds /* 15743ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15753ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15763ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15773ddcd056SLinus Torvalds * for the common case. 15783ddcd056SLinus Torvalds */ 1579d63ff28fSAl Viro static inline int should_follow_link(struct nameidata *nd, struct path *link, int follow) 15803ddcd056SLinus Torvalds { 1581d63ff28fSAl Viro if (likely(!d_is_symlink(link->dentry))) 1582d63ff28fSAl Viro return 0; 1583d63ff28fSAl Viro if (!follow) 1584d63ff28fSAl Viro return 0; 1585d63ff28fSAl Viro return pick_link(nd, link); 15863ddcd056SLinus Torvalds } 15873ddcd056SLinus Torvalds 15884693a547SAl Viro enum {WALK_GET = 1, WALK_PUT = 2}; 15894693a547SAl Viro 15904693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1591ce57dfc1SAl Viro { 1592caa85634SAl Viro struct path path; 1593ce57dfc1SAl Viro struct inode *inode; 1594ce57dfc1SAl Viro int err; 1595ce57dfc1SAl Viro /* 1596ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1597ce57dfc1SAl Viro * to be able to know about the current root directory and 1598ce57dfc1SAl Viro * parent relationships. 1599ce57dfc1SAl Viro */ 16004693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 16014693a547SAl Viro err = handle_dots(nd, nd->last_type); 16024693a547SAl Viro if (flags & WALK_PUT) 16034693a547SAl Viro put_link(nd); 16044693a547SAl Viro return err; 16054693a547SAl Viro } 1606caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1607ce57dfc1SAl Viro if (unlikely(err)) { 1608697f514dSMiklos Szeredi if (err < 0) 1609f0a9ba70SAl Viro return err; 1610697f514dSMiklos Szeredi 1611caa85634SAl Viro err = lookup_slow(nd, &path); 1612697f514dSMiklos Szeredi if (err < 0) 1613f0a9ba70SAl Viro return err; 1614697f514dSMiklos Szeredi 1615caa85634SAl Viro inode = path.dentry->d_inode; 1616697f514dSMiklos Szeredi err = -ENOENT; 1617caa85634SAl Viro if (d_is_negative(path.dentry)) 1618697f514dSMiklos Szeredi goto out_path_put; 1619766c4cbfSAl Viro } 1620697f514dSMiklos Szeredi 16214693a547SAl Viro if (flags & WALK_PUT) 16224693a547SAl Viro put_link(nd); 1623d63ff28fSAl Viro err = should_follow_link(nd, &path, flags & WALK_GET); 1624d63ff28fSAl Viro if (unlikely(err)) 1625d63ff28fSAl Viro return err; 1626caa85634SAl Viro path_to_nameidata(&path, nd); 1627ce57dfc1SAl Viro nd->inode = inode; 1628ce57dfc1SAl Viro return 0; 1629697f514dSMiklos Szeredi 1630697f514dSMiklos Szeredi out_path_put: 1631caa85634SAl Viro path_to_nameidata(&path, 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 == '/')); 18178620c238SAl Viro if (unlikely(!*name)) { 18188620c238SAl Viro OK: 1819368ee9baSAl Viro /* pathname body, done */ 18208620c238SAl Viro if (!nd->depth) 18218620c238SAl Viro return 0; 18228620c238SAl Viro name = nd->stack[nd->depth - 1].name; 1823368ee9baSAl Viro /* trailing symlink, done */ 18248620c238SAl Viro if (!name) 18258620c238SAl Viro return 0; 18268620c238SAl Viro /* last component of nested symlink */ 18274693a547SAl Viro err = walk_component(nd, WALK_GET | WALK_PUT); 18288620c238SAl Viro } else { 18294693a547SAl Viro err = walk_component(nd, WALK_GET); 18308620c238SAl Viro } 1831ce57dfc1SAl Viro if (err < 0) 1832f0a9ba70SAl Viro break; 1833fe479a58SAl Viro 1834ce57dfc1SAl Viro if (err) { 1835626de996SAl Viro const char *s = get_link(nd); 18365a460275SAl Viro 1837172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1838172a39a0SAl Viro err = PTR_ERR(s); 18391bc4b813SAl Viro break; 1840172a39a0SAl Viro } 1841172a39a0SAl Viro err = 0; 184212b09578SAl Viro if (unlikely(!s)) { 184312b09578SAl Viro /* jumped */ 1844b9ff4429SAl Viro put_link(nd); 184512b09578SAl Viro } else { 1846071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 184732cd7468SAl Viro name = s; 18489e18f10aSAl Viro continue; 184948c8b0c5SAl Viro } 185031e6b01fSNick Piggin } 185144b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18523ddcd056SLinus Torvalds err = -ENOTDIR; 18533ddcd056SLinus Torvalds break; 18545f4a6a69SAl Viro } 1855ce57dfc1SAl Viro } 18561da177e4SLinus Torvalds return err; 185707681481SAl Viro } 18581da177e4SLinus Torvalds 1859368ee9baSAl Viro static const char *path_init(int dfd, const struct filename *name, 1860368ee9baSAl Viro unsigned int flags, struct nameidata *nd) 186131e6b01fSNick Piggin { 186231e6b01fSNick Piggin int retval = 0; 1863fd2f7cb5SAl Viro const char *s = name->name; 186431e6b01fSNick Piggin 186531e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1866980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 186731e6b01fSNick Piggin nd->depth = 0; 1868368ee9baSAl Viro nd->total_link_count = 0; 18695b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1870b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1871b18825a7SDavid Howells struct inode *inode = root->d_inode; 1872fd2f7cb5SAl Viro if (*s) { 187344b1d530SMiklos Szeredi if (!d_can_lookup(root)) 1874368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 18755b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18765b6ca027SAl Viro if (retval) 1877368ee9baSAl Viro return ERR_PTR(retval); 187873d049a4SAl Viro } 18795b6ca027SAl Viro nd->path = nd->root; 18805b6ca027SAl Viro nd->inode = inode; 18815b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18828b61e74fSAl Viro rcu_read_lock(); 18835b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 188448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18855b6ca027SAl Viro } else { 18865b6ca027SAl Viro path_get(&nd->path); 18875b6ca027SAl Viro } 1888368ee9baSAl Viro return s; 18895b6ca027SAl Viro } 18905b6ca027SAl Viro 189131e6b01fSNick Piggin nd->root.mnt = NULL; 189231e6b01fSNick Piggin 189348a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1894fd2f7cb5SAl Viro if (*s == '/') { 1895e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18968b61e74fSAl Viro rcu_read_lock(); 18977bd88377SAl Viro nd->seq = set_root_rcu(nd); 1898e41f7d4eSAl Viro } else { 1899e41f7d4eSAl Viro set_root(nd); 1900e41f7d4eSAl Viro path_get(&nd->root); 1901e41f7d4eSAl Viro } 190231e6b01fSNick Piggin nd->path = nd->root; 190331e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1904e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 190531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1906c28cc364SNick Piggin unsigned seq; 190731e6b01fSNick Piggin 19088b61e74fSAl Viro rcu_read_lock(); 190931e6b01fSNick Piggin 1910c28cc364SNick Piggin do { 1911c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 191231e6b01fSNick Piggin nd->path = fs->pwd; 1913c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1914c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1915e41f7d4eSAl Viro } else { 1916e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1917e41f7d4eSAl Viro } 191831e6b01fSNick Piggin } else { 1919582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19202903ff01SAl Viro struct fd f = fdget_raw(dfd); 192131e6b01fSNick Piggin struct dentry *dentry; 192231e6b01fSNick Piggin 19232903ff01SAl Viro if (!f.file) 1924368ee9baSAl Viro return ERR_PTR(-EBADF); 192531e6b01fSNick Piggin 19262903ff01SAl Viro dentry = f.file->f_path.dentry; 192731e6b01fSNick Piggin 1928fd2f7cb5SAl Viro if (*s) { 192944b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19302903ff01SAl Viro fdput(f); 1931368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 1932f52e0c11SAl Viro } 19332903ff01SAl Viro } 19342903ff01SAl Viro 19352903ff01SAl Viro nd->path = f.file->f_path; 1936e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19378b61e74fSAl Viro rcu_read_lock(); 193834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 193934a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 19405590ff0dSUlrich Drepper } else { 19412903ff01SAl Viro path_get(&nd->path); 194234a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 19431da177e4SLinus Torvalds } 194434a26b99SAl Viro fdput(f); 1945368ee9baSAl Viro return s; 1946e41f7d4eSAl Viro } 1947e41f7d4eSAl Viro 194831e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19494023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1950368ee9baSAl Viro return s; 19514023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1952368ee9baSAl Viro return s; 19534023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19544023bfc9SAl Viro nd->root.mnt = NULL; 19554023bfc9SAl Viro rcu_read_unlock(); 1956368ee9baSAl Viro return ERR_PTR(-ECHILD); 19579b4a9b14SAl Viro } 19589b4a9b14SAl Viro 1959893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1960893b7775SAl Viro { 1961893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1962893b7775SAl Viro path_put(&nd->root); 1963893b7775SAl Viro nd->root.mnt = NULL; 1964893b7775SAl Viro } 19659b4a9b14SAl Viro } 19669b4a9b14SAl Viro 19673bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 196895fa25d9SAl Viro { 196995fa25d9SAl Viro const char *s; 1970fec2fa24SAl Viro int error = may_follow_link(nd); 1971deb106c6SAl Viro if (unlikely(error)) 19723bdba28bSAl Viro return ERR_PTR(error); 197395fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 1974fab51e8aSAl Viro nd->stack[0].name = NULL; 19753b2e7f75SAl Viro s = get_link(nd); 1976deb106c6SAl Viro return s ? s : ""; 197795fa25d9SAl Viro } 197895fa25d9SAl Viro 1979caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 1980bd92d7feSAl Viro { 1981bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 1982bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 1983bd92d7feSAl Viro 1984bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 1985deb106c6SAl Viro return walk_component(nd, 19864693a547SAl Viro nd->flags & LOOKUP_FOLLOW 19874693a547SAl Viro ? nd->depth 19884693a547SAl Viro ? WALK_PUT | WALK_GET 19894693a547SAl Viro : WALK_GET 19904693a547SAl Viro : 0); 1991bd92d7feSAl Viro } 1992bd92d7feSAl Viro 19939b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 19945eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 19959b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 19969b4a9b14SAl Viro { 1997368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 1998bd92d7feSAl Viro int err; 199931e6b01fSNick Piggin 2000368ee9baSAl Viro if (IS_ERR(s)) 2001368ee9baSAl Viro return PTR_ERR(s); 20023bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 20033bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 20043bdba28bSAl Viro s = trailing_symlink(nd); 20053bdba28bSAl Viro if (IS_ERR(s)) { 20063bdba28bSAl Viro err = PTR_ERR(s); 20076d7b5aaeSAl Viro break; 2008bd92d7feSAl Viro } 2009bd92d7feSAl Viro } 20109f1fafeeSAl Viro if (!err) 20119f1fafeeSAl Viro err = complete_walk(nd); 2012bd92d7feSAl Viro 2013deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2014deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2015bd23a539SAl Viro err = -ENOTDIR; 2016deb106c6SAl Viro if (err) 2017deb106c6SAl Viro terminate_walk(nd); 201816c2cd71SAl Viro 2019893b7775SAl Viro path_cleanup(nd); 2020bd92d7feSAl Viro return err; 202131e6b01fSNick Piggin } 202231e6b01fSNick Piggin 2023873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2024873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2025873f1eedSJeff Layton { 2026894bc8c4SAl Viro int retval; 2027756daf26SNeilBrown struct nameidata *saved_nd = set_nameidata(nd); 2028894bc8c4SAl Viro 2029894bc8c4SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2030873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20315eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2032873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20335eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2034873f1eedSJeff Layton 2035873f1eedSJeff Layton if (likely(!retval)) 2036adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2037756daf26SNeilBrown restore_nameidata(saved_nd); 2038873f1eedSJeff Layton return retval; 2039873f1eedSJeff Layton } 2040873f1eedSJeff Layton 20418bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20428bcb77faSAl Viro static int path_parentat(int dfd, const struct filename *name, 20438bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20448bcb77faSAl Viro { 2045368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2046368ee9baSAl Viro int err; 2047368ee9baSAl Viro if (IS_ERR(s)) 2048368ee9baSAl Viro return PTR_ERR(s); 2049368ee9baSAl Viro err = link_path_walk(s, nd); 20508bcb77faSAl Viro if (!err) 20518bcb77faSAl Viro err = complete_walk(nd); 2052deb106c6SAl Viro if (err) 2053deb106c6SAl Viro terminate_walk(nd); 20548bcb77faSAl Viro path_cleanup(nd); 20558bcb77faSAl Viro return err; 20568bcb77faSAl Viro } 20578bcb77faSAl Viro 20588bcb77faSAl Viro static int filename_parentat(int dfd, struct filename *name, 20598bcb77faSAl Viro unsigned int flags, struct nameidata *nd) 20608bcb77faSAl Viro { 20618bcb77faSAl Viro int retval; 20628bcb77faSAl Viro struct nameidata *saved_nd = set_nameidata(nd); 20638bcb77faSAl Viro 20648bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); 20658bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 20668bcb77faSAl Viro retval = path_parentat(dfd, name, flags, nd); 20678bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 20688bcb77faSAl Viro retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); 20698bcb77faSAl Viro 20708bcb77faSAl Viro if (likely(!retval)) 20718bcb77faSAl Viro audit_inode(name, nd->path.dentry, LOOKUP_PARENT); 20728bcb77faSAl Viro restore_nameidata(saved_nd); 20738bcb77faSAl Viro return retval; 20748bcb77faSAl Viro } 20758bcb77faSAl Viro 207679714f72SAl Viro /* does lookup, returns the object with parent locked */ 207779714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20785590ff0dSUlrich Drepper { 207951689104SPaul Moore struct filename *filename = getname_kernel(name); 208079714f72SAl Viro struct nameidata nd; 208179714f72SAl Viro struct dentry *d; 208251689104SPaul Moore int err; 208351689104SPaul Moore 208451689104SPaul Moore if (IS_ERR(filename)) 208551689104SPaul Moore return ERR_CAST(filename); 208651689104SPaul Moore 20878bcb77faSAl Viro err = filename_parentat(AT_FDCWD, filename, 0, &nd); 208851689104SPaul Moore if (err) { 208951689104SPaul Moore d = ERR_PTR(err); 209051689104SPaul Moore goto out; 209151689104SPaul Moore } 209279714f72SAl Viro if (nd.last_type != LAST_NORM) { 209379714f72SAl Viro path_put(&nd.path); 209451689104SPaul Moore d = ERR_PTR(-EINVAL); 209551689104SPaul Moore goto out; 209679714f72SAl Viro } 209779714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20981e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 209979714f72SAl Viro if (IS_ERR(d)) { 210079714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 210179714f72SAl Viro path_put(&nd.path); 210251689104SPaul Moore goto out; 210379714f72SAl Viro } 210479714f72SAl Viro *path = nd.path; 210551689104SPaul Moore out: 210651689104SPaul Moore putname(filename); 210779714f72SAl Viro return d; 21085590ff0dSUlrich Drepper } 21095590ff0dSUlrich Drepper 2110d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2111d1811465SAl Viro { 2112d1811465SAl Viro struct nameidata nd; 211374eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 211474eb8cc5SAl Viro int res = PTR_ERR(filename); 211574eb8cc5SAl Viro 211674eb8cc5SAl Viro if (!IS_ERR(filename)) { 211774eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 211874eb8cc5SAl Viro putname(filename); 2119d1811465SAl Viro if (!res) 2120d1811465SAl Viro *path = nd.path; 212174eb8cc5SAl Viro } 2122d1811465SAl Viro return res; 2123d1811465SAl Viro } 21244d359507SAl Viro EXPORT_SYMBOL(kern_path); 2125d1811465SAl Viro 212616f18200SJosef 'Jeff' Sipek /** 212716f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 212816f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 212916f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 213016f18200SJosef 'Jeff' Sipek * @name: pointer to file name 213116f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2132e0a01249SAl Viro * @path: pointer to struct path to fill 213316f18200SJosef 'Jeff' Sipek */ 213416f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 213516f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2136e0a01249SAl Viro struct path *path) 213716f18200SJosef 'Jeff' Sipek { 213874eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 213974eb8cc5SAl Viro int err = PTR_ERR(filename); 214074eb8cc5SAl Viro 214174eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 214274eb8cc5SAl Viro 214374eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 214474eb8cc5SAl Viro if (!IS_ERR(filename)) { 2145e0a01249SAl Viro struct nameidata nd; 2146e0a01249SAl Viro nd.root.dentry = dentry; 2147e0a01249SAl Viro nd.root.mnt = mnt; 214874eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 214974eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2150e0a01249SAl Viro if (!err) 2151e0a01249SAl Viro *path = nd.path; 215274eb8cc5SAl Viro putname(filename); 215374eb8cc5SAl Viro } 2154e0a01249SAl Viro return err; 215516f18200SJosef 'Jeff' Sipek } 21564d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 215716f18200SJosef 'Jeff' Sipek 2158eead1911SChristoph Hellwig /** 2159a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2160eead1911SChristoph Hellwig * @name: pathname component to lookup 2161eead1911SChristoph Hellwig * @base: base directory to lookup from 2162eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2163eead1911SChristoph Hellwig * 2164a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21659e7543e9SAl Viro * not be called by generic code. 2166eead1911SChristoph Hellwig */ 2167057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2168057f6c01SJames Morris { 2169057f6c01SJames Morris struct qstr this; 21706a96ba54SAl Viro unsigned int c; 2171cda309deSMiklos Szeredi int err; 2172057f6c01SJames Morris 21732f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21742f9092e1SDavid Woodhouse 21756a96ba54SAl Viro this.name = name; 21766a96ba54SAl Viro this.len = len; 21770145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21786a96ba54SAl Viro if (!len) 21796a96ba54SAl Viro return ERR_PTR(-EACCES); 21806a96ba54SAl Viro 218121d8a15aSAl Viro if (unlikely(name[0] == '.')) { 218221d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 218321d8a15aSAl Viro return ERR_PTR(-EACCES); 218421d8a15aSAl Viro } 218521d8a15aSAl Viro 21866a96ba54SAl Viro while (len--) { 21876a96ba54SAl Viro c = *(const unsigned char *)name++; 21886a96ba54SAl Viro if (c == '/' || c == '\0') 21896a96ba54SAl Viro return ERR_PTR(-EACCES); 21906a96ba54SAl Viro } 21915a202bcdSAl Viro /* 21925a202bcdSAl Viro * See if the low-level filesystem might want 21935a202bcdSAl Viro * to use its own hash.. 21945a202bcdSAl Viro */ 21955a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2196da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21975a202bcdSAl Viro if (err < 0) 21985a202bcdSAl Viro return ERR_PTR(err); 21995a202bcdSAl Viro } 2200eead1911SChristoph Hellwig 2201cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2202cda309deSMiklos Szeredi if (err) 2203cda309deSMiklos Szeredi return ERR_PTR(err); 2204cda309deSMiklos Szeredi 220572bd866aSAl Viro return __lookup_hash(&this, base, 0); 2206057f6c01SJames Morris } 22074d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2208057f6c01SJames Morris 22091fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22101fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22111da177e4SLinus Torvalds { 22122d8f3038SAl Viro struct nameidata nd; 221391a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22141da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22151da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22162d8f3038SAl Viro 22172d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22182d8f3038SAl Viro 2219873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22201da177e4SLinus Torvalds putname(tmp); 22212d8f3038SAl Viro if (!err) 22222d8f3038SAl Viro *path = nd.path; 22231da177e4SLinus Torvalds } 22241da177e4SLinus Torvalds return err; 22251da177e4SLinus Torvalds } 22261da177e4SLinus Torvalds 22271fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22281fa1e7f6SAndy Whitcroft struct path *path) 22291fa1e7f6SAndy Whitcroft { 2230f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22311fa1e7f6SAndy Whitcroft } 22324d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22331fa1e7f6SAndy Whitcroft 2234873f1eedSJeff Layton /* 2235873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2236873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2237873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2238873f1eedSJeff Layton * path-walking is complete. 2239873f1eedSJeff Layton */ 224091a27b2aSJeff Layton static struct filename * 2241f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2242f5beed75SAl Viro struct path *parent, 2243f5beed75SAl Viro struct qstr *last, 2244f5beed75SAl Viro int *type, 22459e790bd6SJeff Layton unsigned int flags) 22462ad94ae6SAl Viro { 2247f5beed75SAl Viro struct nameidata nd; 224891a27b2aSJeff Layton struct filename *s = getname(path); 22492ad94ae6SAl Viro int error; 22502ad94ae6SAl Viro 22519e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22529e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22539e790bd6SJeff Layton 22542ad94ae6SAl Viro if (IS_ERR(s)) 225591a27b2aSJeff Layton return s; 22562ad94ae6SAl Viro 22578bcb77faSAl Viro error = filename_parentat(dfd, s, flags, &nd); 225891a27b2aSJeff Layton if (error) { 22592ad94ae6SAl Viro putname(s); 226091a27b2aSJeff Layton return ERR_PTR(error); 226191a27b2aSJeff Layton } 2262f5beed75SAl Viro *parent = nd.path; 2263f5beed75SAl Viro *last = nd.last; 2264f5beed75SAl Viro *type = nd.last_type; 22652ad94ae6SAl Viro 226691a27b2aSJeff Layton return s; 22672ad94ae6SAl Viro } 22682ad94ae6SAl Viro 22698033426eSJeff Layton /** 2270197df04cSAl Viro * mountpoint_last - look up last component for umount 22718033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22728033426eSJeff Layton * @path: pointer to container for result 22738033426eSJeff Layton * 22748033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22758033426eSJeff Layton * need to resolve the path without doing any revalidation. 22768033426eSJeff Layton * 22778033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22788033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22798033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22808033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22818033426eSJeff Layton * bogus and it doesn't exist. 22828033426eSJeff Layton * 22838033426eSJeff Layton * Returns: 22848033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22858033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22868033426eSJeff Layton * put in this case. 22878033426eSJeff Layton * 22888033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22898033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22908033426eSJeff Layton * The nd->path reference will also be put. 22918033426eSJeff Layton * 22928033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22938033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22948033426eSJeff Layton * to the link, and nd->path will *not* be put. 22958033426eSJeff Layton */ 22968033426eSJeff Layton static int 2297197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22988033426eSJeff Layton { 22998033426eSJeff Layton int error = 0; 23008033426eSJeff Layton struct dentry *dentry; 23018033426eSJeff Layton struct dentry *dir = nd->path.dentry; 23028033426eSJeff Layton 230335759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 230435759521SAl Viro if (nd->flags & LOOKUP_RCU) { 2305deb106c6SAl Viro if (unlazy_walk(nd, NULL)) 2306deb106c6SAl Viro return -ECHILD; 23078033426eSJeff Layton } 23088033426eSJeff Layton 23098033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23108033426eSJeff Layton 23118033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23128033426eSJeff Layton error = handle_dots(nd, nd->last_type); 231335759521SAl Viro if (error) 2314deb106c6SAl Viro return error; 23158033426eSJeff Layton dentry = dget(nd->path.dentry); 231635759521SAl Viro goto done; 23178033426eSJeff Layton } 23188033426eSJeff Layton 23198033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23208033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23218033426eSJeff Layton if (!dentry) { 23228033426eSJeff Layton /* 23238033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23248033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23258033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23268033426eSJeff Layton */ 23278033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23288033426eSJeff Layton if (!dentry) { 2329bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2330deb106c6SAl Viro return -ENOMEM; 23318033426eSJeff Layton } 233235759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 2333bcceeebaSDave Jones if (IS_ERR(dentry)) { 2334bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 2335deb106c6SAl Viro return PTR_ERR(dentry); 23368033426eSJeff Layton } 2337bcceeebaSDave Jones } 23388033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23398033426eSJeff Layton 234035759521SAl Viro done: 2341698934dfSDavid Howells if (d_is_negative(dentry)) { 23428033426eSJeff Layton dput(dentry); 2343deb106c6SAl Viro return -ENOENT; 234435759521SAl Viro } 2345191d7f73SAl Viro if (nd->depth) 2346191d7f73SAl Viro put_link(nd); 23478033426eSJeff Layton path->dentry = dentry; 2348295dc39dSVasily Averin path->mnt = nd->path.mnt; 2349d63ff28fSAl Viro error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW); 2350deb106c6SAl Viro if (unlikely(error)) 2351d63ff28fSAl Viro return error; 2352295dc39dSVasily Averin mntget(path->mnt); 23538033426eSJeff Layton follow_mount(path); 2354deb106c6SAl Viro return 0; 23558033426eSJeff Layton } 23568033426eSJeff Layton 23578033426eSJeff Layton /** 2358197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23598033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23608033426eSJeff Layton * @name: full pathname to walk 2361606d6fe3SRandy Dunlap * @path: pointer to container for result 23628033426eSJeff Layton * @flags: lookup flags 23638033426eSJeff Layton * 23648033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2365606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23668033426eSJeff Layton */ 23678033426eSJeff Layton static int 2368668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 236946afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 23708033426eSJeff Layton { 2371368ee9baSAl Viro const char *s = path_init(dfd, name, flags, nd); 2372368ee9baSAl Viro int err; 2373368ee9baSAl Viro if (IS_ERR(s)) 2374368ee9baSAl Viro return PTR_ERR(s); 23753bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 23763bdba28bSAl Viro (err = mountpoint_last(nd, path)) > 0) { 23773bdba28bSAl Viro s = trailing_symlink(nd); 23783bdba28bSAl Viro if (IS_ERR(s)) { 23793bdba28bSAl Viro err = PTR_ERR(s); 23808033426eSJeff Layton break; 23818033426eSJeff Layton } 23823bdba28bSAl Viro } 2383deb106c6SAl Viro terminate_walk(nd); 238446afd6f6SAl Viro path_cleanup(nd); 23858033426eSJeff Layton return err; 23868033426eSJeff Layton } 23878033426eSJeff Layton 23882d864651SAl Viro static int 2389668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 23902d864651SAl Viro unsigned int flags) 23912d864651SAl Viro { 2392756daf26SNeilBrown struct nameidata nd, *saved; 2393cbaab2dbSAl Viro int error; 2394668696dcSAl Viro if (IS_ERR(name)) 2395668696dcSAl Viro return PTR_ERR(name); 2396756daf26SNeilBrown saved = set_nameidata(&nd); 239746afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 23982d864651SAl Viro if (unlikely(error == -ECHILD)) 239946afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24002d864651SAl Viro if (unlikely(error == -ESTALE)) 240146afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24022d864651SAl Viro if (likely(!error)) 2403668696dcSAl Viro audit_inode(name, path->dentry, 0); 2404756daf26SNeilBrown restore_nameidata(saved); 2405668696dcSAl Viro putname(name); 24062d864651SAl Viro return error; 24072d864651SAl Viro } 24082d864651SAl Viro 24098033426eSJeff Layton /** 2410197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24118033426eSJeff Layton * @dfd: directory file descriptor 24128033426eSJeff Layton * @name: pathname from userland 24138033426eSJeff Layton * @flags: lookup flags 24148033426eSJeff Layton * @path: pointer to container to hold result 24158033426eSJeff Layton * 24168033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24178033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24188033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24198033426eSJeff Layton * and avoid revalidating the last component. 24208033426eSJeff Layton * 24218033426eSJeff Layton * Returns 0 and populates "path" on success. 24228033426eSJeff Layton */ 24238033426eSJeff Layton int 2424197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24258033426eSJeff Layton struct path *path) 24268033426eSJeff Layton { 2427cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24288033426eSJeff Layton } 24298033426eSJeff Layton 24302d864651SAl Viro int 24312d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24322d864651SAl Viro unsigned int flags) 24332d864651SAl Viro { 2434cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24352d864651SAl Viro } 24362d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24372d864651SAl Viro 2438cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24391da177e4SLinus Torvalds { 24408e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2441da9592edSDavid Howells 24428e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24431da177e4SLinus Torvalds return 0; 24448e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24451da177e4SLinus Torvalds return 0; 244623adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24471da177e4SLinus Torvalds } 2448cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24491da177e4SLinus Torvalds 24501da177e4SLinus Torvalds /* 24511da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24521da177e4SLinus Torvalds * whether the type of victim is right. 24531da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24541da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24551da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24561da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24571da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24581da177e4SLinus Torvalds * a. be owner of dir, or 24591da177e4SLinus Torvalds * b. be owner of victim, or 24601da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24611da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24621da177e4SLinus Torvalds * links pointing to it. 24631da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24641da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24651da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24661da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24671da177e4SLinus Torvalds * nfs_async_unlink(). 24681da177e4SLinus Torvalds */ 2469b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24701da177e4SLinus Torvalds { 2471b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24721da177e4SLinus Torvalds int error; 24731da177e4SLinus Torvalds 2474b18825a7SDavid Howells if (d_is_negative(victim)) 24751da177e4SLinus Torvalds return -ENOENT; 2476b18825a7SDavid Howells BUG_ON(!inode); 24771da177e4SLinus Torvalds 24781da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24794fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24801da177e4SLinus Torvalds 2481f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24821da177e4SLinus Torvalds if (error) 24831da177e4SLinus Torvalds return error; 24841da177e4SLinus Torvalds if (IS_APPEND(dir)) 24851da177e4SLinus Torvalds return -EPERM; 2486b18825a7SDavid Howells 2487b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2488b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24891da177e4SLinus Torvalds return -EPERM; 24901da177e4SLinus Torvalds if (isdir) { 249144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24921da177e4SLinus Torvalds return -ENOTDIR; 24931da177e4SLinus Torvalds if (IS_ROOT(victim)) 24941da177e4SLinus Torvalds return -EBUSY; 249544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24961da177e4SLinus Torvalds return -EISDIR; 24971da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 24981da177e4SLinus Torvalds return -ENOENT; 24991da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25001da177e4SLinus Torvalds return -EBUSY; 25011da177e4SLinus Torvalds return 0; 25021da177e4SLinus Torvalds } 25031da177e4SLinus Torvalds 25041da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25051da177e4SLinus Torvalds * dir. 25061da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25071da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25081da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25091da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25101da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25111da177e4SLinus Torvalds */ 2512a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25131da177e4SLinus Torvalds { 251414e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25151da177e4SLinus Torvalds if (child->d_inode) 25161da177e4SLinus Torvalds return -EEXIST; 25171da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25181da177e4SLinus Torvalds return -ENOENT; 2519f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25201da177e4SLinus Torvalds } 25211da177e4SLinus Torvalds 25221da177e4SLinus Torvalds /* 25231da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25241da177e4SLinus Torvalds */ 25251da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25261da177e4SLinus Torvalds { 25271da177e4SLinus Torvalds struct dentry *p; 25281da177e4SLinus Torvalds 25291da177e4SLinus Torvalds if (p1 == p2) { 2530f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25311da177e4SLinus Torvalds return NULL; 25321da177e4SLinus Torvalds } 25331da177e4SLinus Torvalds 2534a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25351da177e4SLinus Torvalds 2536e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2537e2761a11SOGAWA Hirofumi if (p) { 2538f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2539f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25401da177e4SLinus Torvalds return p; 25411da177e4SLinus Torvalds } 25421da177e4SLinus Torvalds 2543e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2544e2761a11SOGAWA Hirofumi if (p) { 2545f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2546f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25471da177e4SLinus Torvalds return p; 25481da177e4SLinus Torvalds } 25491da177e4SLinus Torvalds 2550f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2551d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25521da177e4SLinus Torvalds return NULL; 25531da177e4SLinus Torvalds } 25544d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25551da177e4SLinus Torvalds 25561da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25571da177e4SLinus Torvalds { 25581b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25591da177e4SLinus Torvalds if (p1 != p2) { 25601b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2561a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25621da177e4SLinus Torvalds } 25631da177e4SLinus Torvalds } 25644d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25651da177e4SLinus Torvalds 25664acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2567312b63fbSAl Viro bool want_excl) 25681da177e4SLinus Torvalds { 2569a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25701da177e4SLinus Torvalds if (error) 25711da177e4SLinus Torvalds return error; 25721da177e4SLinus Torvalds 2573acfa4380SAl Viro if (!dir->i_op->create) 25741da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25751da177e4SLinus Torvalds mode &= S_IALLUGO; 25761da177e4SLinus Torvalds mode |= S_IFREG; 25771da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25781da177e4SLinus Torvalds if (error) 25791da177e4SLinus Torvalds return error; 2580312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2581a74574aaSStephen Smalley if (!error) 2582f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25831da177e4SLinus Torvalds return error; 25841da177e4SLinus Torvalds } 25854d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25861da177e4SLinus Torvalds 258773d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25881da177e4SLinus Torvalds { 25893fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25901da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25911da177e4SLinus Torvalds int error; 25921da177e4SLinus Torvalds 2593bcda7652SAl Viro /* O_PATH? */ 2594bcda7652SAl Viro if (!acc_mode) 2595bcda7652SAl Viro return 0; 2596bcda7652SAl Viro 25971da177e4SLinus Torvalds if (!inode) 25981da177e4SLinus Torvalds return -ENOENT; 25991da177e4SLinus Torvalds 2600c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2601c8fe8f30SChristoph Hellwig case S_IFLNK: 26021da177e4SLinus Torvalds return -ELOOP; 2603c8fe8f30SChristoph Hellwig case S_IFDIR: 2604c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26051da177e4SLinus Torvalds return -EISDIR; 2606c8fe8f30SChristoph Hellwig break; 2607c8fe8f30SChristoph Hellwig case S_IFBLK: 2608c8fe8f30SChristoph Hellwig case S_IFCHR: 26093fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26101da177e4SLinus Torvalds return -EACCES; 2611c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2612c8fe8f30SChristoph Hellwig case S_IFIFO: 2613c8fe8f30SChristoph Hellwig case S_IFSOCK: 26141da177e4SLinus Torvalds flag &= ~O_TRUNC; 2615c8fe8f30SChristoph Hellwig break; 26164a3fd211SDave Hansen } 2617b41572e9SDave Hansen 26183fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2619b41572e9SDave Hansen if (error) 2620b41572e9SDave Hansen return error; 26216146f0d5SMimi Zohar 26221da177e4SLinus Torvalds /* 26231da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26241da177e4SLinus Torvalds */ 26251da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26268737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26277715b521SAl Viro return -EPERM; 26281da177e4SLinus Torvalds if (flag & O_TRUNC) 26297715b521SAl Viro return -EPERM; 26301da177e4SLinus Torvalds } 26311da177e4SLinus Torvalds 26321da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26332e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26347715b521SAl Viro return -EPERM; 26351da177e4SLinus Torvalds 2636f3c7691eSJ. Bruce Fields return 0; 26377715b521SAl Viro } 26387715b521SAl Viro 2639e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26407715b521SAl Viro { 2641e1181ee6SJeff Layton struct path *path = &filp->f_path; 26427715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26437715b521SAl Viro int error = get_write_access(inode); 26441da177e4SLinus Torvalds if (error) 26457715b521SAl Viro return error; 26461da177e4SLinus Torvalds /* 26471da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26481da177e4SLinus Torvalds */ 2649d7a06983SJeff Layton error = locks_verify_locked(filp); 2650be6d3e56SKentaro Takeda if (!error) 2651ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26521da177e4SLinus Torvalds if (!error) { 26537715b521SAl Viro error = do_truncate(path->dentry, 0, 2654d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2655e1181ee6SJeff Layton filp); 26561da177e4SLinus Torvalds } 26571da177e4SLinus Torvalds put_write_access(inode); 2658acd0c935SMimi Zohar return error; 26591da177e4SLinus Torvalds } 26601da177e4SLinus Torvalds 2661d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2662d57999e1SDave Hansen { 26638a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26648a5e929dSAl Viro flag--; 2665d57999e1SDave Hansen return flag; 2666d57999e1SDave Hansen } 2667d57999e1SDave Hansen 2668d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2669d18e9008SMiklos Szeredi { 2670d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2671d18e9008SMiklos Szeredi if (error) 2672d18e9008SMiklos Szeredi return error; 2673d18e9008SMiklos Szeredi 2674d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2675d18e9008SMiklos Szeredi if (error) 2676d18e9008SMiklos Szeredi return error; 2677d18e9008SMiklos Szeredi 2678d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2679d18e9008SMiklos Szeredi } 2680d18e9008SMiklos Szeredi 26811acf0af9SDavid Howells /* 26821acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26831acf0af9SDavid Howells * dentry. 26841acf0af9SDavid Howells * 26851acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26861acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26871acf0af9SDavid Howells * 26881acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26891acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26901acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26911acf0af9SDavid Howells * 26921acf0af9SDavid Howells * Returns an error code otherwise. 26931acf0af9SDavid Howells */ 26942675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 269530d90494SAl Viro struct path *path, struct file *file, 2696015c3bbcSMiklos Szeredi const struct open_flags *op, 269764894cf8SAl Viro bool got_write, bool need_lookup, 269847237687SAl Viro int *opened) 2699d18e9008SMiklos Szeredi { 2700d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2701d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2702d18e9008SMiklos Szeredi umode_t mode; 2703d18e9008SMiklos Szeredi int error; 2704d18e9008SMiklos Szeredi int acc_mode; 2705d18e9008SMiklos Szeredi int create_error = 0; 2706d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2707116cc022SMiklos Szeredi bool excl; 2708d18e9008SMiklos Szeredi 2709d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2710d18e9008SMiklos Szeredi 2711d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2712d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27132675a4ebSAl Viro error = -ENOENT; 2714d18e9008SMiklos Szeredi goto out; 2715d18e9008SMiklos Szeredi } 2716d18e9008SMiklos Szeredi 271762b259d8SMiklos Szeredi mode = op->mode; 2718d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2719d18e9008SMiklos Szeredi mode &= ~current_umask(); 2720d18e9008SMiklos Szeredi 2721116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2722116cc022SMiklos Szeredi if (excl) 2723d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2724d18e9008SMiklos Szeredi 2725d18e9008SMiklos Szeredi /* 2726d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2727d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2728d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2729d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2730d18e9008SMiklos Szeredi * 2731d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2732d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2733d18e9008SMiklos Szeredi */ 273464894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 273564894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 273664894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2737d18e9008SMiklos Szeredi /* 2738d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2739d18e9008SMiklos Szeredi * back to lookup + open 2740d18e9008SMiklos Szeredi */ 2741d18e9008SMiklos Szeredi goto no_open; 2742d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2743d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 274464894cf8SAl Viro create_error = -EROFS; 2745d18e9008SMiklos Szeredi goto no_open; 2746d18e9008SMiklos Szeredi } else { 2747d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 274864894cf8SAl Viro create_error = -EROFS; 2749d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2750d18e9008SMiklos Szeredi } 2751d18e9008SMiklos Szeredi } 2752d18e9008SMiklos Szeredi 2753d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 275438227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2755d18e9008SMiklos Szeredi if (error) { 2756d18e9008SMiklos Szeredi create_error = error; 2757d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2758d18e9008SMiklos Szeredi goto no_open; 2759d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2760d18e9008SMiklos Szeredi } 2761d18e9008SMiklos Szeredi } 2762d18e9008SMiklos Szeredi 2763d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2764d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2765d18e9008SMiklos Szeredi 276630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 276730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 276830d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 276947237687SAl Viro opened); 2770d9585277SAl Viro if (error < 0) { 2771d9585277SAl Viro if (create_error && error == -ENOENT) 2772d9585277SAl Viro error = create_error; 2773d18e9008SMiklos Szeredi goto out; 2774d18e9008SMiklos Szeredi } 2775d18e9008SMiklos Szeredi 2776d9585277SAl Viro if (error) { /* returned 1, that is */ 277730d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27782675a4ebSAl Viro error = -EIO; 2779d18e9008SMiklos Szeredi goto out; 2780d18e9008SMiklos Szeredi } 278130d90494SAl Viro if (file->f_path.dentry) { 2782d18e9008SMiklos Szeredi dput(dentry); 278330d90494SAl Viro dentry = file->f_path.dentry; 2784d18e9008SMiklos Szeredi } 278503da633aSAl Viro if (*opened & FILE_CREATED) 278603da633aSAl Viro fsnotify_create(dir, dentry); 278703da633aSAl Viro if (!dentry->d_inode) { 278803da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 278903da633aSAl Viro if (create_error) { 279062b2ce96SSage Weil error = create_error; 279162b2ce96SSage Weil goto out; 279262b2ce96SSage Weil } 279303da633aSAl Viro } else { 279403da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 279503da633aSAl Viro error = -EEXIST; 279603da633aSAl Viro goto out; 279703da633aSAl Viro } 279803da633aSAl Viro } 2799d18e9008SMiklos Szeredi goto looked_up; 2800d18e9008SMiklos Szeredi } 2801d18e9008SMiklos Szeredi 2802d18e9008SMiklos Szeredi /* 2803d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2804d18e9008SMiklos Szeredi * here. 2805d18e9008SMiklos Szeredi */ 280603da633aSAl Viro acc_mode = op->acc_mode; 280703da633aSAl Viro if (*opened & FILE_CREATED) { 280803da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 280903da633aSAl Viro fsnotify_create(dir, dentry); 281003da633aSAl Viro acc_mode = MAY_OPEN; 281103da633aSAl Viro } 28122675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28132675a4ebSAl Viro if (error) 28142675a4ebSAl Viro fput(file); 2815d18e9008SMiklos Szeredi 2816d18e9008SMiklos Szeredi out: 2817d18e9008SMiklos Szeredi dput(dentry); 28182675a4ebSAl Viro return error; 2819d18e9008SMiklos Szeredi 2820d18e9008SMiklos Szeredi no_open: 2821d18e9008SMiklos Szeredi if (need_lookup) { 282272bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2823d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28242675a4ebSAl Viro return PTR_ERR(dentry); 2825d18e9008SMiklos Szeredi 2826d18e9008SMiklos Szeredi if (create_error) { 2827d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2828d18e9008SMiklos Szeredi 28292675a4ebSAl Viro error = create_error; 2830d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2831d18e9008SMiklos Szeredi if (!dentry->d_inode) 2832d18e9008SMiklos Szeredi goto out; 2833d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2834d18e9008SMiklos Szeredi goto out; 2835d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2836e36cb0b8SDavid Howells d_is_reg(dentry)) { 2837d18e9008SMiklos Szeredi goto out; 2838d18e9008SMiklos Szeredi } 2839d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2840d18e9008SMiklos Szeredi } 2841d18e9008SMiklos Szeredi } 2842d18e9008SMiklos Szeredi looked_up: 2843d18e9008SMiklos Szeredi path->dentry = dentry; 2844d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28452675a4ebSAl Viro return 1; 2846d18e9008SMiklos Szeredi } 2847d18e9008SMiklos Szeredi 284831e6b01fSNick Piggin /* 28491acf0af9SDavid Howells * Look up and maybe create and open the last component. 2850d58ffd35SMiklos Szeredi * 2851d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2852d58ffd35SMiklos Szeredi * 28531acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28541acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28551acf0af9SDavid Howells * 28561acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28571acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28581acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28591acf0af9SDavid Howells * specified then a negative dentry may be returned. 28601acf0af9SDavid Howells * 28611acf0af9SDavid Howells * An error code is returned otherwise. 28621acf0af9SDavid Howells * 28631acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28641acf0af9SDavid Howells * cleared otherwise prior to returning. 2865d58ffd35SMiklos Szeredi */ 28662675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 286730d90494SAl Viro struct file *file, 2868d58ffd35SMiklos Szeredi const struct open_flags *op, 286964894cf8SAl Viro bool got_write, int *opened) 2870d58ffd35SMiklos Szeredi { 2871d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 287254ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2873d58ffd35SMiklos Szeredi struct dentry *dentry; 2874d58ffd35SMiklos Szeredi int error; 287554ef4872SMiklos Szeredi bool need_lookup; 2876d58ffd35SMiklos Szeredi 287747237687SAl Viro *opened &= ~FILE_CREATED; 2878201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2879d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28802675a4ebSAl Viro return PTR_ERR(dentry); 2881d58ffd35SMiklos Szeredi 2882d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2883d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2884d18e9008SMiklos Szeredi goto out_no_open; 2885d18e9008SMiklos Szeredi 2886d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 288764894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 288847237687SAl Viro need_lookup, opened); 2889d18e9008SMiklos Szeredi } 2890d18e9008SMiklos Szeredi 289154ef4872SMiklos Szeredi if (need_lookup) { 289254ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 289354ef4872SMiklos Szeredi 289472bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 289554ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28962675a4ebSAl Viro return PTR_ERR(dentry); 289754ef4872SMiklos Szeredi } 289854ef4872SMiklos Szeredi 2899d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2900d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2901d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2902d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2903d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2904d58ffd35SMiklos Szeredi /* 2905d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2906d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2907d58ffd35SMiklos Szeredi * the time when the file is created and when 2908d58ffd35SMiklos Szeredi * a permanent write count is taken through 2909015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2910d58ffd35SMiklos Szeredi */ 291164894cf8SAl Viro if (!got_write) { 291264894cf8SAl Viro error = -EROFS; 2913d58ffd35SMiklos Szeredi goto out_dput; 291464894cf8SAl Viro } 291547237687SAl Viro *opened |= FILE_CREATED; 2916d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2917d58ffd35SMiklos Szeredi if (error) 2918d58ffd35SMiklos Szeredi goto out_dput; 2919312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2920312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2921d58ffd35SMiklos Szeredi if (error) 2922d58ffd35SMiklos Szeredi goto out_dput; 2923d58ffd35SMiklos Szeredi } 2924d18e9008SMiklos Szeredi out_no_open: 2925d58ffd35SMiklos Szeredi path->dentry = dentry; 2926d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29272675a4ebSAl Viro return 1; 2928d58ffd35SMiklos Szeredi 2929d58ffd35SMiklos Szeredi out_dput: 2930d58ffd35SMiklos Szeredi dput(dentry); 29312675a4ebSAl Viro return error; 2932d58ffd35SMiklos Szeredi } 2933d58ffd35SMiklos Szeredi 2934d58ffd35SMiklos Szeredi /* 2935fe2d35ffSAl Viro * Handle the last step of open() 293631e6b01fSNick Piggin */ 2937896475d5SAl Viro static int do_last(struct nameidata *nd, 293830d90494SAl Viro struct file *file, const struct open_flags *op, 2939669abf4eSJeff Layton int *opened, struct filename *name) 2940fb1cc555SAl Viro { 2941a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2942ca344a89SAl Viro int open_flag = op->open_flag; 294377d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 294464894cf8SAl Viro bool got_write = false; 2945bcda7652SAl Viro int acc_mode = op->acc_mode; 2946a1eb3315SMiklos Szeredi struct inode *inode; 294716b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2948896475d5SAl Viro struct path path; 294916b1c1cdSMiklos Szeredi bool retried = false; 295016c2cd71SAl Viro int error; 2951fb1cc555SAl Viro 2952c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2953c3e380b0SAl Viro nd->flags |= op->intent; 2954c3e380b0SAl Viro 2955bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2956fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2957deb106c6SAl Viro if (unlikely(error)) 29582675a4ebSAl Viro return error; 2959e83db167SMiklos Szeredi goto finish_open; 29601f36f774SAl Viro } 2961a2c36b45SAl Viro 2962ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2963fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2964fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2965fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2966896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 296771574865SMiklos Szeredi if (likely(!error)) 296871574865SMiklos Szeredi goto finish_lookup; 296971574865SMiklos Szeredi 2970ce57dfc1SAl Viro if (error < 0) 2971deb106c6SAl Viro return error; 2972a1eb3315SMiklos Szeredi 297337d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2974b6183df7SMiklos Szeredi } else { 2975fe2d35ffSAl Viro /* create side of things */ 2976a3fbbde7SAl Viro /* 2977b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2978b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2979b6183df7SMiklos Szeredi * about to look up 2980a3fbbde7SAl Viro */ 29819f1fafeeSAl Viro error = complete_walk(nd); 2982e8bb73dfSAl Viro if (error) 29832675a4ebSAl Viro return error; 2984fe2d35ffSAl Viro 298533e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 29861f36f774SAl Viro /* trailing slashes? */ 2987deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 2988deb106c6SAl Viro return -EISDIR; 2989b6183df7SMiklos Szeredi } 29901f36f774SAl Viro 299116b1c1cdSMiklos Szeredi retry_lookup: 299264894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 299364894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 299464894cf8SAl Viro if (!error) 299564894cf8SAl Viro got_write = true; 299664894cf8SAl Viro /* 299764894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 299864894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 299964894cf8SAl Viro * dropping this one anyway. 300064894cf8SAl Viro */ 300164894cf8SAl Viro } 3002a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3003896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3004fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3005fb1cc555SAl Viro 30062675a4ebSAl Viro if (error <= 0) { 30072675a4ebSAl Viro if (error) 3008d58ffd35SMiklos Szeredi goto out; 30096c0d46c4SAl Viro 301047237687SAl Viro if ((*opened & FILE_CREATED) || 3011496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 301277d660a8SMiklos Szeredi will_truncate = false; 3013d18e9008SMiklos Szeredi 3014adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3015d18e9008SMiklos Szeredi goto opened; 3016d18e9008SMiklos Szeredi } 3017d18e9008SMiklos Szeredi 301847237687SAl Viro if (*opened & FILE_CREATED) { 30199b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3020ca344a89SAl Viro open_flag &= ~O_TRUNC; 302177d660a8SMiklos Szeredi will_truncate = false; 3022bcda7652SAl Viro acc_mode = MAY_OPEN; 3023896475d5SAl Viro path_to_nameidata(&path, nd); 3024e83db167SMiklos Szeredi goto finish_open_created; 3025fb1cc555SAl Viro } 3026fb1cc555SAl Viro 3027fb1cc555SAl Viro /* 30283134f37eSJeff Layton * create/update audit record if it already exists. 3029fb1cc555SAl Viro */ 3030896475d5SAl Viro if (d_is_positive(path.dentry)) 3031896475d5SAl Viro audit_inode(name, path.dentry, 0); 3032fb1cc555SAl Viro 3033d18e9008SMiklos Szeredi /* 3034d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3035d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3036d18e9008SMiklos Szeredi * necessary...) 3037d18e9008SMiklos Szeredi */ 303864894cf8SAl Viro if (got_write) { 3039d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 304064894cf8SAl Viro got_write = false; 3041d18e9008SMiklos Szeredi } 3042d18e9008SMiklos Szeredi 3043deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3044deb106c6SAl Viro path_to_nameidata(&path, nd); 3045deb106c6SAl Viro return -EEXIST; 3046deb106c6SAl Viro } 3047fb1cc555SAl Viro 3048756daf26SNeilBrown error = follow_managed(&path, nd); 3049deb106c6SAl Viro if (unlikely(error < 0)) 3050deb106c6SAl Viro return error; 3051a3fbbde7SAl Viro 3052decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3053896475d5SAl Viro inode = path.dentry->d_inode; 3054deb106c6SAl Viro if (unlikely(d_is_negative(path.dentry))) { 3055896475d5SAl Viro path_to_nameidata(&path, nd); 3056deb106c6SAl Viro return -ENOENT; 305754c33e7fSMiklos Szeredi } 3058766c4cbfSAl Viro finish_lookup: 3059191d7f73SAl Viro if (nd->depth) 3060191d7f73SAl Viro put_link(nd); 3061d63ff28fSAl Viro error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW); 3062deb106c6SAl Viro if (unlikely(error)) 3063d63ff28fSAl Viro return error; 3064fb1cc555SAl Viro 3065896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3066896475d5SAl Viro path_to_nameidata(&path, nd); 3067deb106c6SAl Viro return -ELOOP; 3068a5cfe2d5SAl Viro } 3069a5cfe2d5SAl Viro 3070896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3071896475d5SAl Viro path_to_nameidata(&path, nd); 307216b1c1cdSMiklos Szeredi } else { 307316b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3074896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3075896475d5SAl Viro nd->path.dentry = path.dentry; 307616b1c1cdSMiklos Szeredi 307716b1c1cdSMiklos Szeredi } 3078decf3400SMiklos Szeredi nd->inode = inode; 3079a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3080bc77daa7SAl Viro finish_open: 3081a3fbbde7SAl Viro error = complete_walk(nd); 308216b1c1cdSMiklos Szeredi if (error) { 308316b1c1cdSMiklos Szeredi path_put(&save_parent); 30842675a4ebSAl Viro return error; 308516b1c1cdSMiklos Szeredi } 3086bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3087fb1cc555SAl Viro error = -EISDIR; 308844b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 30892675a4ebSAl Viro goto out; 3090af2f5542SMiklos Szeredi error = -ENOTDIR; 309144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 30922675a4ebSAl Viro goto out; 30934bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 309477d660a8SMiklos Szeredi will_truncate = false; 30956c0d46c4SAl Viro 30960f9d1a10SAl Viro if (will_truncate) { 30970f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 30980f9d1a10SAl Viro if (error) 30992675a4ebSAl Viro goto out; 310064894cf8SAl Viro got_write = true; 31010f9d1a10SAl Viro } 3102e83db167SMiklos Szeredi finish_open_created: 3103bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3104ca344a89SAl Viro if (error) 31052675a4ebSAl Viro goto out; 31064aa7c634SMiklos Szeredi 31074aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31084aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31094aa7c634SMiklos Szeredi if (!error) { 31104aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31114aa7c634SMiklos Szeredi } else { 311230d90494SAl Viro if (error == -EOPENSTALE) 3113f60dc3dbSMiklos Szeredi goto stale_open; 3114015c3bbcSMiklos Szeredi goto out; 3115f60dc3dbSMiklos Szeredi } 3116a8277b9bSMiklos Szeredi opened: 31172675a4ebSAl Viro error = open_check_o_direct(file); 3118015c3bbcSMiklos Szeredi if (error) 3119015c3bbcSMiklos Szeredi goto exit_fput; 31203034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3121aa4caadbSMiklos Szeredi if (error) 3122aa4caadbSMiklos Szeredi goto exit_fput; 3123aa4caadbSMiklos Szeredi 31240f9d1a10SAl Viro if (will_truncate) { 31252675a4ebSAl Viro error = handle_truncate(file); 3126aa4caadbSMiklos Szeredi if (error) 3127aa4caadbSMiklos Szeredi goto exit_fput; 31280f9d1a10SAl Viro } 3129ca344a89SAl Viro out: 313064894cf8SAl Viro if (got_write) 31310f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 313216b1c1cdSMiklos Szeredi path_put(&save_parent); 31332675a4ebSAl Viro return error; 3134fb1cc555SAl Viro 3135015c3bbcSMiklos Szeredi exit_fput: 31362675a4ebSAl Viro fput(file); 31372675a4ebSAl Viro goto out; 3138015c3bbcSMiklos Szeredi 3139f60dc3dbSMiklos Szeredi stale_open: 3140f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3141f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3142f60dc3dbSMiklos Szeredi goto out; 3143f60dc3dbSMiklos Szeredi 3144f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3145f60dc3dbSMiklos Szeredi path_put(&nd->path); 3146f60dc3dbSMiklos Szeredi nd->path = save_parent; 3147f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3148f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3149f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 315064894cf8SAl Viro if (got_write) { 3151f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 315264894cf8SAl Viro got_write = false; 3153f60dc3dbSMiklos Szeredi } 3154f60dc3dbSMiklos Szeredi retried = true; 3155f60dc3dbSMiklos Szeredi goto retry_lookup; 3156fb1cc555SAl Viro } 3157fb1cc555SAl Viro 315860545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 315960545d0dSAl Viro struct nameidata *nd, int flags, 316060545d0dSAl Viro const struct open_flags *op, 316160545d0dSAl Viro struct file *file, int *opened) 316260545d0dSAl Viro { 316360545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 316460545d0dSAl Viro struct dentry *dentry, *child; 316560545d0dSAl Viro struct inode *dir; 31665eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 316760545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 316860545d0dSAl Viro if (unlikely(error)) 316960545d0dSAl Viro return error; 317060545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 317160545d0dSAl Viro if (unlikely(error)) 317260545d0dSAl Viro goto out; 317360545d0dSAl Viro /* we want directory to be writable */ 317460545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 317560545d0dSAl Viro if (error) 317660545d0dSAl Viro goto out2; 317760545d0dSAl Viro dentry = nd->path.dentry; 317860545d0dSAl Viro dir = dentry->d_inode; 317960545d0dSAl Viro if (!dir->i_op->tmpfile) { 318060545d0dSAl Viro error = -EOPNOTSUPP; 318160545d0dSAl Viro goto out2; 318260545d0dSAl Viro } 318360545d0dSAl Viro child = d_alloc(dentry, &name); 318460545d0dSAl Viro if (unlikely(!child)) { 318560545d0dSAl Viro error = -ENOMEM; 318660545d0dSAl Viro goto out2; 318760545d0dSAl Viro } 318860545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 318960545d0dSAl Viro nd->flags |= op->intent; 319060545d0dSAl Viro dput(nd->path.dentry); 319160545d0dSAl Viro nd->path.dentry = child; 319260545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 319360545d0dSAl Viro if (error) 319460545d0dSAl Viro goto out2; 319560545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 319669a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 319769a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 319860545d0dSAl Viro if (error) 319960545d0dSAl Viro goto out2; 320060545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 320160545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 320260545d0dSAl Viro if (error) 320360545d0dSAl Viro goto out2; 320460545d0dSAl Viro error = open_check_o_direct(file); 3205f4e0c30cSAl Viro if (error) { 320660545d0dSAl Viro fput(file); 3207f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3208f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3209f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3210f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3211f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3212f4e0c30cSAl Viro } 321360545d0dSAl Viro out2: 321460545d0dSAl Viro mnt_drop_write(nd->path.mnt); 321560545d0dSAl Viro out: 321660545d0dSAl Viro path_put(&nd->path); 321760545d0dSAl Viro return error; 321860545d0dSAl Viro } 321960545d0dSAl Viro 3220669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 322173d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32221da177e4SLinus Torvalds { 3223368ee9baSAl Viro const char *s; 322430d90494SAl Viro struct file *file; 322547237687SAl Viro int opened = 0; 322613aab428SAl Viro int error; 322731e6b01fSNick Piggin 322830d90494SAl Viro file = get_empty_filp(); 32291afc99beSAl Viro if (IS_ERR(file)) 32301afc99beSAl Viro return file; 323131e6b01fSNick Piggin 323230d90494SAl Viro file->f_flags = op->open_flag; 323331e6b01fSNick Piggin 3234bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 323560545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3236f15133dfSAl Viro goto out2; 323760545d0dSAl Viro } 323860545d0dSAl Viro 3239368ee9baSAl Viro s = path_init(dfd, pathname, flags, nd); 3240368ee9baSAl Viro if (IS_ERR(s)) { 3241368ee9baSAl Viro put_filp(file); 3242368ee9baSAl Viro return ERR_CAST(s); 3243368ee9baSAl Viro } 32443bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 32453bdba28bSAl Viro (error = do_last(nd, file, op, &opened, pathname)) > 0) { 324673d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 32473bdba28bSAl Viro s = trailing_symlink(nd); 32483bdba28bSAl Viro if (IS_ERR(s)) { 32493bdba28bSAl Viro error = PTR_ERR(s); 32502675a4ebSAl Viro break; 3251806b681cSAl Viro } 32523bdba28bSAl Viro } 3253deb106c6SAl Viro terminate_walk(nd); 3254893b7775SAl Viro path_cleanup(nd); 3255f15133dfSAl Viro out2: 32562675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32572675a4ebSAl Viro BUG_ON(!error); 325830d90494SAl Viro put_filp(file); 3259015c3bbcSMiklos Szeredi } 32602675a4ebSAl Viro if (unlikely(error)) { 32612675a4ebSAl Viro if (error == -EOPENSTALE) { 32622675a4ebSAl Viro if (flags & LOOKUP_RCU) 32632675a4ebSAl Viro error = -ECHILD; 32642675a4ebSAl Viro else 32652675a4ebSAl Viro error = -ESTALE; 32662675a4ebSAl Viro } 32672675a4ebSAl Viro file = ERR_PTR(error); 32682675a4ebSAl Viro } 32692675a4ebSAl Viro return file; 3270de459215SKirill Korotaev } 32711da177e4SLinus Torvalds 3272669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3273f9652e10SAl Viro const struct open_flags *op) 327413aab428SAl Viro { 3275756daf26SNeilBrown struct nameidata nd, *saved_nd = set_nameidata(&nd); 3276f9652e10SAl Viro int flags = op->lookup_flags; 327713aab428SAl Viro struct file *filp; 327813aab428SAl Viro 327973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 328013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 328173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 328213aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 328373d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 3284756daf26SNeilBrown restore_nameidata(saved_nd); 328513aab428SAl Viro return filp; 328613aab428SAl Viro } 328713aab428SAl Viro 328873d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3289f9652e10SAl Viro const char *name, const struct open_flags *op) 329073d049a4SAl Viro { 3291756daf26SNeilBrown struct nameidata nd, *saved_nd; 329273d049a4SAl Viro struct file *file; 329351689104SPaul Moore struct filename *filename; 3294f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 329573d049a4SAl Viro 329673d049a4SAl Viro nd.root.mnt = mnt; 329773d049a4SAl Viro nd.root.dentry = dentry; 329873d049a4SAl Viro 3299b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 330073d049a4SAl Viro return ERR_PTR(-ELOOP); 330173d049a4SAl Viro 330251689104SPaul Moore filename = getname_kernel(name); 330351689104SPaul Moore if (unlikely(IS_ERR(filename))) 330451689104SPaul Moore return ERR_CAST(filename); 330551689104SPaul Moore 3306756daf26SNeilBrown saved_nd = set_nameidata(&nd); 330751689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 330873d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 330951689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 331073d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 331151689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 3312756daf26SNeilBrown restore_nameidata(saved_nd); 331351689104SPaul Moore putname(filename); 331473d049a4SAl Viro return file; 331573d049a4SAl Viro } 331673d049a4SAl Viro 3317fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33181ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33191da177e4SLinus Torvalds { 3320c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3321ed75e95dSAl Viro struct nameidata nd; 3322c30dabfeSJan Kara int err2; 33231ac12b4bSJeff Layton int error; 33241ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33251ac12b4bSJeff Layton 33261ac12b4bSJeff Layton /* 33271ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33281ac12b4bSJeff Layton * other flags passed in are ignored! 33291ac12b4bSJeff Layton */ 33301ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33311ac12b4bSJeff Layton 33328bcb77faSAl Viro error = filename_parentat(dfd, name, lookup_flags, &nd); 3333ed75e95dSAl Viro if (error) 3334ed75e95dSAl Viro return ERR_PTR(error); 33351da177e4SLinus Torvalds 3336c663e5d8SChristoph Hellwig /* 3337c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3338c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3339c663e5d8SChristoph Hellwig */ 3340ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3341ed75e95dSAl Viro goto out; 3342ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3343ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3344c663e5d8SChristoph Hellwig 3345c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3346c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3347c663e5d8SChristoph Hellwig /* 3348c663e5d8SChristoph Hellwig * Do the final lookup. 3349c663e5d8SChristoph Hellwig */ 3350ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33516a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33521da177e4SLinus Torvalds if (IS_ERR(dentry)) 3353a8104a9fSAl Viro goto unlock; 3354c663e5d8SChristoph Hellwig 3355a8104a9fSAl Viro error = -EEXIST; 3356b18825a7SDavid Howells if (d_is_positive(dentry)) 3357a8104a9fSAl Viro goto fail; 3358b18825a7SDavid Howells 3359c663e5d8SChristoph Hellwig /* 3360c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3361c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3362c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3363c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3364c663e5d8SChristoph Hellwig */ 3365ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3366a8104a9fSAl Viro error = -ENOENT; 3367ed75e95dSAl Viro goto fail; 3368e9baf6e5SAl Viro } 3369c30dabfeSJan Kara if (unlikely(err2)) { 3370c30dabfeSJan Kara error = err2; 3371a8104a9fSAl Viro goto fail; 3372c30dabfeSJan Kara } 3373ed75e95dSAl Viro *path = nd.path; 3374e9baf6e5SAl Viro return dentry; 33751da177e4SLinus Torvalds fail: 3376a8104a9fSAl Viro dput(dentry); 3377a8104a9fSAl Viro dentry = ERR_PTR(error); 3378a8104a9fSAl Viro unlock: 3379dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3380c30dabfeSJan Kara if (!err2) 3381c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3382ed75e95dSAl Viro out: 3383dae6ad8fSAl Viro path_put(&nd.path); 3384ed75e95dSAl Viro return dentry; 3385dae6ad8fSAl Viro } 3386fa14a0b8SAl Viro 3387fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3388fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3389fa14a0b8SAl Viro { 339051689104SPaul Moore struct filename *filename = getname_kernel(pathname); 339151689104SPaul Moore struct dentry *res; 339251689104SPaul Moore 339351689104SPaul Moore if (IS_ERR(filename)) 339451689104SPaul Moore return ERR_CAST(filename); 339551689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 339651689104SPaul Moore putname(filename); 339751689104SPaul Moore return res; 3398fa14a0b8SAl Viro } 3399dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3400dae6ad8fSAl Viro 3401921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3402921a1650SAl Viro { 3403921a1650SAl Viro dput(dentry); 3404921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3405a8104a9fSAl Viro mnt_drop_write(path->mnt); 3406921a1650SAl Viro path_put(path); 3407921a1650SAl Viro } 3408921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3409921a1650SAl Viro 34101ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34111ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3412dae6ad8fSAl Viro { 341391a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3414dae6ad8fSAl Viro struct dentry *res; 3415dae6ad8fSAl Viro if (IS_ERR(tmp)) 3416dae6ad8fSAl Viro return ERR_CAST(tmp); 3417fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3418dae6ad8fSAl Viro putname(tmp); 3419dae6ad8fSAl Viro return res; 3420dae6ad8fSAl Viro } 3421dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3422dae6ad8fSAl Viro 34231a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34241da177e4SLinus Torvalds { 3425a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34261da177e4SLinus Torvalds 34271da177e4SLinus Torvalds if (error) 34281da177e4SLinus Torvalds return error; 34291da177e4SLinus Torvalds 3430975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34311da177e4SLinus Torvalds return -EPERM; 34321da177e4SLinus Torvalds 3433acfa4380SAl Viro if (!dir->i_op->mknod) 34341da177e4SLinus Torvalds return -EPERM; 34351da177e4SLinus Torvalds 343608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 343708ce5f16SSerge E. Hallyn if (error) 343808ce5f16SSerge E. Hallyn return error; 343908ce5f16SSerge E. Hallyn 34401da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34411da177e4SLinus Torvalds if (error) 34421da177e4SLinus Torvalds return error; 34431da177e4SLinus Torvalds 34441da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3445a74574aaSStephen Smalley if (!error) 3446f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34471da177e4SLinus Torvalds return error; 34481da177e4SLinus Torvalds } 34494d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34501da177e4SLinus Torvalds 3451f69aac00SAl Viro static int may_mknod(umode_t mode) 3452463c3197SDave Hansen { 3453463c3197SDave Hansen switch (mode & S_IFMT) { 3454463c3197SDave Hansen case S_IFREG: 3455463c3197SDave Hansen case S_IFCHR: 3456463c3197SDave Hansen case S_IFBLK: 3457463c3197SDave Hansen case S_IFIFO: 3458463c3197SDave Hansen case S_IFSOCK: 3459463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3460463c3197SDave Hansen return 0; 3461463c3197SDave Hansen case S_IFDIR: 3462463c3197SDave Hansen return -EPERM; 3463463c3197SDave Hansen default: 3464463c3197SDave Hansen return -EINVAL; 3465463c3197SDave Hansen } 3466463c3197SDave Hansen } 3467463c3197SDave Hansen 34688208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34692e4d0924SHeiko Carstens unsigned, dev) 34701da177e4SLinus Torvalds { 34711da177e4SLinus Torvalds struct dentry *dentry; 3472dae6ad8fSAl Viro struct path path; 3473dae6ad8fSAl Viro int error; 3474972567f1SJeff Layton unsigned int lookup_flags = 0; 34751da177e4SLinus Torvalds 34768e4bfca1SAl Viro error = may_mknod(mode); 34778e4bfca1SAl Viro if (error) 34788e4bfca1SAl Viro return error; 3479972567f1SJeff Layton retry: 3480972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3481dae6ad8fSAl Viro if (IS_ERR(dentry)) 3482dae6ad8fSAl Viro return PTR_ERR(dentry); 34832ad94ae6SAl Viro 3484dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3485ce3b0f8dSAl Viro mode &= ~current_umask(); 3486dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3487be6d3e56SKentaro Takeda if (error) 3488a8104a9fSAl Viro goto out; 34891da177e4SLinus Torvalds switch (mode & S_IFMT) { 34901da177e4SLinus Torvalds case 0: case S_IFREG: 3491312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 34921da177e4SLinus Torvalds break; 34931da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3494dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 34951da177e4SLinus Torvalds new_decode_dev(dev)); 34961da177e4SLinus Torvalds break; 34971da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3498dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 34991da177e4SLinus Torvalds break; 35001da177e4SLinus Torvalds } 3501a8104a9fSAl Viro out: 3502921a1650SAl Viro done_path_create(&path, dentry); 3503972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3504972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3505972567f1SJeff Layton goto retry; 3506972567f1SJeff Layton } 35071da177e4SLinus Torvalds return error; 35081da177e4SLinus Torvalds } 35091da177e4SLinus Torvalds 35108208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35115590ff0dSUlrich Drepper { 35125590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35135590ff0dSUlrich Drepper } 35145590ff0dSUlrich Drepper 351518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35161da177e4SLinus Torvalds { 3517a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35188de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35191da177e4SLinus Torvalds 35201da177e4SLinus Torvalds if (error) 35211da177e4SLinus Torvalds return error; 35221da177e4SLinus Torvalds 3523acfa4380SAl Viro if (!dir->i_op->mkdir) 35241da177e4SLinus Torvalds return -EPERM; 35251da177e4SLinus Torvalds 35261da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35271da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35281da177e4SLinus Torvalds if (error) 35291da177e4SLinus Torvalds return error; 35301da177e4SLinus Torvalds 35318de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35328de52778SAl Viro return -EMLINK; 35338de52778SAl Viro 35341da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3535a74574aaSStephen Smalley if (!error) 3536f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35371da177e4SLinus Torvalds return error; 35381da177e4SLinus Torvalds } 35394d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35401da177e4SLinus Torvalds 3541a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35421da177e4SLinus Torvalds { 35436902d925SDave Hansen struct dentry *dentry; 3544dae6ad8fSAl Viro struct path path; 3545dae6ad8fSAl Viro int error; 3546b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35471da177e4SLinus Torvalds 3548b76d8b82SJeff Layton retry: 3549b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35506902d925SDave Hansen if (IS_ERR(dentry)) 3551dae6ad8fSAl Viro return PTR_ERR(dentry); 35526902d925SDave Hansen 3553dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3554ce3b0f8dSAl Viro mode &= ~current_umask(); 3555dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3556a8104a9fSAl Viro if (!error) 3557dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3558921a1650SAl Viro done_path_create(&path, dentry); 3559b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3560b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3561b76d8b82SJeff Layton goto retry; 3562b76d8b82SJeff Layton } 35631da177e4SLinus Torvalds return error; 35641da177e4SLinus Torvalds } 35651da177e4SLinus Torvalds 3566a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35675590ff0dSUlrich Drepper { 35685590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35695590ff0dSUlrich Drepper } 35705590ff0dSUlrich Drepper 35711da177e4SLinus Torvalds /* 3572a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3573c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3574a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3575a71905f0SSage Weil * then we drop the dentry now. 35761da177e4SLinus Torvalds * 35771da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35781da177e4SLinus Torvalds * do a 35791da177e4SLinus Torvalds * 35801da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35811da177e4SLinus Torvalds * return -EBUSY; 35821da177e4SLinus Torvalds * 35831da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35841da177e4SLinus Torvalds * that is still in use by something else.. 35851da177e4SLinus Torvalds */ 35861da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 35871da177e4SLinus Torvalds { 35881da177e4SLinus Torvalds shrink_dcache_parent(dentry); 35891da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 359098474236SWaiman Long if (dentry->d_lockref.count == 1) 35911da177e4SLinus Torvalds __d_drop(dentry); 35921da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 35931da177e4SLinus Torvalds } 35944d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 35951da177e4SLinus Torvalds 35961da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 35971da177e4SLinus Torvalds { 35981da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 35991da177e4SLinus Torvalds 36001da177e4SLinus Torvalds if (error) 36011da177e4SLinus Torvalds return error; 36021da177e4SLinus Torvalds 3603acfa4380SAl Viro if (!dir->i_op->rmdir) 36041da177e4SLinus Torvalds return -EPERM; 36051da177e4SLinus Torvalds 36061d2ef590SAl Viro dget(dentry); 36071b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3608912dbc15SSage Weil 36091da177e4SLinus Torvalds error = -EBUSY; 36107af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3611912dbc15SSage Weil goto out; 3612912dbc15SSage Weil 36131da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3614912dbc15SSage Weil if (error) 3615912dbc15SSage Weil goto out; 3616912dbc15SSage Weil 36173cebde24SSage Weil shrink_dcache_parent(dentry); 36181da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3619912dbc15SSage Weil if (error) 3620912dbc15SSage Weil goto out; 3621912dbc15SSage Weil 36221da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3623d83c49f3SAl Viro dont_mount(dentry); 36248ed936b5SEric W. Biederman detach_mounts(dentry); 36251da177e4SLinus Torvalds 3626912dbc15SSage Weil out: 3627912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36281d2ef590SAl Viro dput(dentry); 3629912dbc15SSage Weil if (!error) 3630912dbc15SSage Weil d_delete(dentry); 36311da177e4SLinus Torvalds return error; 36321da177e4SLinus Torvalds } 36334d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36341da177e4SLinus Torvalds 36355590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36361da177e4SLinus Torvalds { 36371da177e4SLinus Torvalds int error = 0; 363891a27b2aSJeff Layton struct filename *name; 36391da177e4SLinus Torvalds struct dentry *dentry; 3640f5beed75SAl Viro struct path path; 3641f5beed75SAl Viro struct qstr last; 3642f5beed75SAl Viro int type; 3643c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3644c6ee9206SJeff Layton retry: 3645f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3646f5beed75SAl Viro &path, &last, &type, lookup_flags); 364791a27b2aSJeff Layton if (IS_ERR(name)) 364891a27b2aSJeff Layton return PTR_ERR(name); 36491da177e4SLinus Torvalds 3650f5beed75SAl Viro switch (type) { 36511da177e4SLinus Torvalds case LAST_DOTDOT: 36521da177e4SLinus Torvalds error = -ENOTEMPTY; 36531da177e4SLinus Torvalds goto exit1; 36541da177e4SLinus Torvalds case LAST_DOT: 36551da177e4SLinus Torvalds error = -EINVAL; 36561da177e4SLinus Torvalds goto exit1; 36571da177e4SLinus Torvalds case LAST_ROOT: 36581da177e4SLinus Torvalds error = -EBUSY; 36591da177e4SLinus Torvalds goto exit1; 36601da177e4SLinus Torvalds } 36610612d9fbSOGAWA Hirofumi 3662f5beed75SAl Viro error = mnt_want_write(path.mnt); 3663c30dabfeSJan Kara if (error) 3664c30dabfeSJan Kara goto exit1; 36650612d9fbSOGAWA Hirofumi 3666f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3667f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 36681da177e4SLinus Torvalds error = PTR_ERR(dentry); 36696902d925SDave Hansen if (IS_ERR(dentry)) 36706902d925SDave Hansen goto exit2; 3671e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3672e6bc45d6STheodore Ts'o error = -ENOENT; 3673e6bc45d6STheodore Ts'o goto exit3; 3674e6bc45d6STheodore Ts'o } 3675f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3676be6d3e56SKentaro Takeda if (error) 3677c30dabfeSJan Kara goto exit3; 3678f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 36790622753bSDave Hansen exit3: 36801da177e4SLinus Torvalds dput(dentry); 36816902d925SDave Hansen exit2: 3682f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3683f5beed75SAl Viro mnt_drop_write(path.mnt); 36841da177e4SLinus Torvalds exit1: 3685f5beed75SAl Viro path_put(&path); 36861da177e4SLinus Torvalds putname(name); 3687c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3688c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3689c6ee9206SJeff Layton goto retry; 3690c6ee9206SJeff Layton } 36911da177e4SLinus Torvalds return error; 36921da177e4SLinus Torvalds } 36931da177e4SLinus Torvalds 36943cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 36955590ff0dSUlrich Drepper { 36965590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 36975590ff0dSUlrich Drepper } 36985590ff0dSUlrich Drepper 3699b21996e3SJ. Bruce Fields /** 3700b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3701b21996e3SJ. Bruce Fields * @dir: parent directory 3702b21996e3SJ. Bruce Fields * @dentry: victim 3703b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3704b21996e3SJ. Bruce Fields * 3705b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3706b21996e3SJ. Bruce Fields * 3707b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3708b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3709b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3710b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3711b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3712b21996e3SJ. Bruce Fields * 3713b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3714b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3715b21996e3SJ. Bruce Fields * to be NFS exported. 3716b21996e3SJ. Bruce Fields */ 3717b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37181da177e4SLinus Torvalds { 37199accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37201da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37211da177e4SLinus Torvalds 37221da177e4SLinus Torvalds if (error) 37231da177e4SLinus Torvalds return error; 37241da177e4SLinus Torvalds 3725acfa4380SAl Viro if (!dir->i_op->unlink) 37261da177e4SLinus Torvalds return -EPERM; 37271da177e4SLinus Torvalds 37289accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37298ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37301da177e4SLinus Torvalds error = -EBUSY; 37311da177e4SLinus Torvalds else { 37321da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3733bec1052eSAl Viro if (!error) { 37345a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37355a14696cSJ. Bruce Fields if (error) 3736b21996e3SJ. Bruce Fields goto out; 37371da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37388ed936b5SEric W. Biederman if (!error) { 3739d83c49f3SAl Viro dont_mount(dentry); 37408ed936b5SEric W. Biederman detach_mounts(dentry); 37418ed936b5SEric W. Biederman } 3742bec1052eSAl Viro } 37431da177e4SLinus Torvalds } 3744b21996e3SJ. Bruce Fields out: 37459accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37461da177e4SLinus Torvalds 37471da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37481da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37499accbb97SJ. Bruce Fields fsnotify_link_count(target); 37501da177e4SLinus Torvalds d_delete(dentry); 37511da177e4SLinus Torvalds } 37520eeca283SRobert Love 37531da177e4SLinus Torvalds return error; 37541da177e4SLinus Torvalds } 37554d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37561da177e4SLinus Torvalds 37571da177e4SLinus Torvalds /* 37581da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37591b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37601da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37611da177e4SLinus Torvalds * while waiting on the I/O. 37621da177e4SLinus Torvalds */ 37635590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37641da177e4SLinus Torvalds { 37652ad94ae6SAl Viro int error; 376691a27b2aSJeff Layton struct filename *name; 37671da177e4SLinus Torvalds struct dentry *dentry; 3768f5beed75SAl Viro struct path path; 3769f5beed75SAl Viro struct qstr last; 3770f5beed75SAl Viro int type; 37711da177e4SLinus Torvalds struct inode *inode = NULL; 3772b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37735d18f813SJeff Layton unsigned int lookup_flags = 0; 37745d18f813SJeff Layton retry: 3775f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3776f5beed75SAl Viro &path, &last, &type, lookup_flags); 377791a27b2aSJeff Layton if (IS_ERR(name)) 377891a27b2aSJeff Layton return PTR_ERR(name); 37792ad94ae6SAl Viro 37801da177e4SLinus Torvalds error = -EISDIR; 3781f5beed75SAl Viro if (type != LAST_NORM) 37821da177e4SLinus Torvalds goto exit1; 37830612d9fbSOGAWA Hirofumi 3784f5beed75SAl Viro error = mnt_want_write(path.mnt); 3785c30dabfeSJan Kara if (error) 3786c30dabfeSJan Kara goto exit1; 3787b21996e3SJ. Bruce Fields retry_deleg: 3788f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3789f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37901da177e4SLinus Torvalds error = PTR_ERR(dentry); 37911da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 37921da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3793f5beed75SAl Viro if (last.name[last.len]) 379450338b88STörök Edwin goto slashes; 37951da177e4SLinus Torvalds inode = dentry->d_inode; 3796b18825a7SDavid Howells if (d_is_negative(dentry)) 3797e6bc45d6STheodore Ts'o goto slashes; 37987de9c6eeSAl Viro ihold(inode); 3799f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3800be6d3e56SKentaro Takeda if (error) 3801c30dabfeSJan Kara goto exit2; 3802f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38031da177e4SLinus Torvalds exit2: 38041da177e4SLinus Torvalds dput(dentry); 38051da177e4SLinus Torvalds } 3806f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38071da177e4SLinus Torvalds if (inode) 38081da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3809b21996e3SJ. Bruce Fields inode = NULL; 3810b21996e3SJ. Bruce Fields if (delegated_inode) { 38115a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3812b21996e3SJ. Bruce Fields if (!error) 3813b21996e3SJ. Bruce Fields goto retry_deleg; 3814b21996e3SJ. Bruce Fields } 3815f5beed75SAl Viro mnt_drop_write(path.mnt); 38161da177e4SLinus Torvalds exit1: 3817f5beed75SAl Viro path_put(&path); 38181da177e4SLinus Torvalds putname(name); 38195d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38205d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38215d18f813SJeff Layton inode = NULL; 38225d18f813SJeff Layton goto retry; 38235d18f813SJeff Layton } 38241da177e4SLinus Torvalds return error; 38251da177e4SLinus Torvalds 38261da177e4SLinus Torvalds slashes: 3827b18825a7SDavid Howells if (d_is_negative(dentry)) 3828b18825a7SDavid Howells error = -ENOENT; 382944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3830b18825a7SDavid Howells error = -EISDIR; 3831b18825a7SDavid Howells else 3832b18825a7SDavid Howells error = -ENOTDIR; 38331da177e4SLinus Torvalds goto exit2; 38341da177e4SLinus Torvalds } 38351da177e4SLinus Torvalds 38362e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38375590ff0dSUlrich Drepper { 38385590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38395590ff0dSUlrich Drepper return -EINVAL; 38405590ff0dSUlrich Drepper 38415590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38425590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38435590ff0dSUlrich Drepper 38445590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38455590ff0dSUlrich Drepper } 38465590ff0dSUlrich Drepper 38473480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38485590ff0dSUlrich Drepper { 38495590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38505590ff0dSUlrich Drepper } 38515590ff0dSUlrich Drepper 3852db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38531da177e4SLinus Torvalds { 3854a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38551da177e4SLinus Torvalds 38561da177e4SLinus Torvalds if (error) 38571da177e4SLinus Torvalds return error; 38581da177e4SLinus Torvalds 3859acfa4380SAl Viro if (!dir->i_op->symlink) 38601da177e4SLinus Torvalds return -EPERM; 38611da177e4SLinus Torvalds 38621da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38631da177e4SLinus Torvalds if (error) 38641da177e4SLinus Torvalds return error; 38651da177e4SLinus Torvalds 38661da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3867a74574aaSStephen Smalley if (!error) 3868f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38691da177e4SLinus Torvalds return error; 38701da177e4SLinus Torvalds } 38714d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38721da177e4SLinus Torvalds 38732e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38742e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38751da177e4SLinus Torvalds { 38762ad94ae6SAl Viro int error; 387791a27b2aSJeff Layton struct filename *from; 38786902d925SDave Hansen struct dentry *dentry; 3879dae6ad8fSAl Viro struct path path; 3880f46d3567SJeff Layton unsigned int lookup_flags = 0; 38811da177e4SLinus Torvalds 38821da177e4SLinus Torvalds from = getname(oldname); 38831da177e4SLinus Torvalds if (IS_ERR(from)) 38841da177e4SLinus Torvalds return PTR_ERR(from); 3885f46d3567SJeff Layton retry: 3886f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 38871da177e4SLinus Torvalds error = PTR_ERR(dentry); 38886902d925SDave Hansen if (IS_ERR(dentry)) 3889dae6ad8fSAl Viro goto out_putname; 38906902d925SDave Hansen 389191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3892a8104a9fSAl Viro if (!error) 389391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3894921a1650SAl Viro done_path_create(&path, dentry); 3895f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3896f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3897f46d3567SJeff Layton goto retry; 3898f46d3567SJeff Layton } 38996902d925SDave Hansen out_putname: 39001da177e4SLinus Torvalds putname(from); 39011da177e4SLinus Torvalds return error; 39021da177e4SLinus Torvalds } 39031da177e4SLinus Torvalds 39043480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39055590ff0dSUlrich Drepper { 39065590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39075590ff0dSUlrich Drepper } 39085590ff0dSUlrich Drepper 3909146a8595SJ. Bruce Fields /** 3910146a8595SJ. Bruce Fields * vfs_link - create a new link 3911146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3912146a8595SJ. Bruce Fields * @dir: new parent 3913146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3914146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3915146a8595SJ. Bruce Fields * 3916146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3917146a8595SJ. Bruce Fields * 3918146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3919146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3920146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3921146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3922146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3923146a8595SJ. Bruce Fields * 3924146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3925146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3926146a8595SJ. Bruce Fields * to be NFS exported. 3927146a8595SJ. Bruce Fields */ 3928146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39291da177e4SLinus Torvalds { 39301da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39318de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39321da177e4SLinus Torvalds int error; 39331da177e4SLinus Torvalds 39341da177e4SLinus Torvalds if (!inode) 39351da177e4SLinus Torvalds return -ENOENT; 39361da177e4SLinus Torvalds 3937a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39381da177e4SLinus Torvalds if (error) 39391da177e4SLinus Torvalds return error; 39401da177e4SLinus Torvalds 39411da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39421da177e4SLinus Torvalds return -EXDEV; 39431da177e4SLinus Torvalds 39441da177e4SLinus Torvalds /* 39451da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39461da177e4SLinus Torvalds */ 39471da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39481da177e4SLinus Torvalds return -EPERM; 3949acfa4380SAl Viro if (!dir->i_op->link) 39501da177e4SLinus Torvalds return -EPERM; 39517e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39521da177e4SLinus Torvalds return -EPERM; 39531da177e4SLinus Torvalds 39541da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39551da177e4SLinus Torvalds if (error) 39561da177e4SLinus Torvalds return error; 39571da177e4SLinus Torvalds 39587e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3959aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3960f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3961aae8a97dSAneesh Kumar K.V error = -ENOENT; 39628de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39638de52778SAl Viro error = -EMLINK; 3964146a8595SJ. Bruce Fields else { 3965146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3966146a8595SJ. Bruce Fields if (!error) 39671da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3968146a8595SJ. Bruce Fields } 3969f4e0c30cSAl Viro 3970f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3971f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3972f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3973f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3974f4e0c30cSAl Viro } 39757e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3976e31e14ecSStephen Smalley if (!error) 39777e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39781da177e4SLinus Torvalds return error; 39791da177e4SLinus Torvalds } 39804d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39811da177e4SLinus Torvalds 39821da177e4SLinus Torvalds /* 39831da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39841da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 39851da177e4SLinus Torvalds * newname. --KAB 39861da177e4SLinus Torvalds * 39871da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 39881da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 39891da177e4SLinus Torvalds * and other special files. --ADM 39901da177e4SLinus Torvalds */ 39912e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 39922e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 39931da177e4SLinus Torvalds { 39941da177e4SLinus Torvalds struct dentry *new_dentry; 3995dae6ad8fSAl Viro struct path old_path, new_path; 3996146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 399711a7b371SAneesh Kumar K.V int how = 0; 39981da177e4SLinus Torvalds int error; 39991da177e4SLinus Torvalds 400011a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4001c04030e1SUlrich Drepper return -EINVAL; 400211a7b371SAneesh Kumar K.V /* 4003f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4004f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4005f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 400611a7b371SAneesh Kumar K.V */ 4007f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4008f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4009f0cc6ffbSLinus Torvalds return -ENOENT; 401011a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4011f0cc6ffbSLinus Torvalds } 4012c04030e1SUlrich Drepper 401311a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 401411a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4015442e31caSJeff Layton retry: 401611a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40171da177e4SLinus Torvalds if (error) 40182ad94ae6SAl Viro return error; 40192ad94ae6SAl Viro 4020442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4021442e31caSJeff Layton (how & LOOKUP_REVAL)); 40221da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40236902d925SDave Hansen if (IS_ERR(new_dentry)) 4024dae6ad8fSAl Viro goto out; 4025dae6ad8fSAl Viro 4026dae6ad8fSAl Viro error = -EXDEV; 4027dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4028dae6ad8fSAl Viro goto out_dput; 4029800179c9SKees Cook error = may_linkat(&old_path); 4030800179c9SKees Cook if (unlikely(error)) 4031800179c9SKees Cook goto out_dput; 4032dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4033be6d3e56SKentaro Takeda if (error) 4034a8104a9fSAl Viro goto out_dput; 4035146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 403675c3f29dSDave Hansen out_dput: 4037921a1650SAl Viro done_path_create(&new_path, new_dentry); 4038146a8595SJ. Bruce Fields if (delegated_inode) { 4039146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4040d22e6338SOleg Drokin if (!error) { 4041d22e6338SOleg Drokin path_put(&old_path); 4042146a8595SJ. Bruce Fields goto retry; 4043146a8595SJ. Bruce Fields } 4044d22e6338SOleg Drokin } 4045442e31caSJeff Layton if (retry_estale(error, how)) { 4046d22e6338SOleg Drokin path_put(&old_path); 4047442e31caSJeff Layton how |= LOOKUP_REVAL; 4048442e31caSJeff Layton goto retry; 4049442e31caSJeff Layton } 40501da177e4SLinus Torvalds out: 40512d8f3038SAl Viro path_put(&old_path); 40521da177e4SLinus Torvalds 40531da177e4SLinus Torvalds return error; 40541da177e4SLinus Torvalds } 40551da177e4SLinus Torvalds 40563480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40575590ff0dSUlrich Drepper { 4058c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40595590ff0dSUlrich Drepper } 40605590ff0dSUlrich Drepper 4061bc27027aSMiklos Szeredi /** 4062bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4063bc27027aSMiklos Szeredi * @old_dir: parent of source 4064bc27027aSMiklos Szeredi * @old_dentry: source 4065bc27027aSMiklos Szeredi * @new_dir: parent of destination 4066bc27027aSMiklos Szeredi * @new_dentry: destination 4067bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4068520c8b16SMiklos Szeredi * @flags: rename flags 4069bc27027aSMiklos Szeredi * 4070bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4071bc27027aSMiklos Szeredi * 4072bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4073bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4074bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4075bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4076bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4077bc27027aSMiklos Szeredi * so. 4078bc27027aSMiklos Szeredi * 4079bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4080bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4081bc27027aSMiklos Szeredi * to be NFS exported. 4082bc27027aSMiklos Szeredi * 40831da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40841da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 40851da177e4SLinus Torvalds * Problems: 4086d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 40871da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 40881da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4089a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 40901da177e4SLinus Torvalds * story. 40916cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 40926cedba89SJ. Bruce Fields * and source (if it is not a directory). 40931b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 40941da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 40951da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4096a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 40971da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 40981da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 40991da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4100a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41011da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41021da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41031da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4104e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41051b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41061da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4107c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41081da177e4SLinus Torvalds * locking]. 41091da177e4SLinus Torvalds */ 41101da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41118e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4112520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41131da177e4SLinus Torvalds { 41141da177e4SLinus Torvalds int error; 4115bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 411659b0df21SEric Paris const unsigned char *old_name; 4117bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4118bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4119da1ce067SMiklos Szeredi bool new_is_dir = false; 4120da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41211da177e4SLinus Torvalds 4122bc27027aSMiklos Szeredi if (source == target) 41231da177e4SLinus Torvalds return 0; 41241da177e4SLinus Torvalds 41251da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41261da177e4SLinus Torvalds if (error) 41271da177e4SLinus Torvalds return error; 41281da177e4SLinus Torvalds 4129da1ce067SMiklos Szeredi if (!target) { 4130a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4131da1ce067SMiklos Szeredi } else { 4132da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4133da1ce067SMiklos Szeredi 4134da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41351da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4136da1ce067SMiklos Szeredi else 4137da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4138da1ce067SMiklos Szeredi } 41391da177e4SLinus Torvalds if (error) 41401da177e4SLinus Torvalds return error; 41411da177e4SLinus Torvalds 41427177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41431da177e4SLinus Torvalds return -EPERM; 41441da177e4SLinus Torvalds 4145520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4146520c8b16SMiklos Szeredi return -EINVAL; 4147520c8b16SMiklos Szeredi 4148bc27027aSMiklos Szeredi /* 4149bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4150bc27027aSMiklos Szeredi * we'll need to flip '..'. 4151bc27027aSMiklos Szeredi */ 4152da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4153da1ce067SMiklos Szeredi if (is_dir) { 4154bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4155bc27027aSMiklos Szeredi if (error) 4156bc27027aSMiklos Szeredi return error; 4157bc27027aSMiklos Szeredi } 4158da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4159da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4160da1ce067SMiklos Szeredi if (error) 4161da1ce067SMiklos Szeredi return error; 4162da1ce067SMiklos Szeredi } 4163da1ce067SMiklos Szeredi } 41640eeca283SRobert Love 41650b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41660b3974ebSMiklos Szeredi flags); 4167bc27027aSMiklos Szeredi if (error) 4168bc27027aSMiklos Szeredi return error; 4169bc27027aSMiklos Szeredi 4170bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4171bc27027aSMiklos Szeredi dget(new_dentry); 4172da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4173bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4174bc27027aSMiklos Szeredi else if (target) 4175bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4176bc27027aSMiklos Szeredi 4177bc27027aSMiklos Szeredi error = -EBUSY; 41787af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4179bc27027aSMiklos Szeredi goto out; 4180bc27027aSMiklos Szeredi 4181da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4182bc27027aSMiklos Szeredi error = -EMLINK; 4183da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4184bc27027aSMiklos Szeredi goto out; 4185da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4186da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4187da1ce067SMiklos Szeredi goto out; 4188da1ce067SMiklos Szeredi } 4189da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4190bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4191da1ce067SMiklos Szeredi if (!is_dir) { 4192bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4193bc27027aSMiklos Szeredi if (error) 4194bc27027aSMiklos Szeredi goto out; 4195da1ce067SMiklos Szeredi } 4196da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4197bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4198bc27027aSMiklos Szeredi if (error) 4199bc27027aSMiklos Szeredi goto out; 4200bc27027aSMiklos Szeredi } 42017177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4202520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4203520c8b16SMiklos Szeredi new_dir, new_dentry); 4204520c8b16SMiklos Szeredi } else { 42057177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4206520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4207520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4208520c8b16SMiklos Szeredi } 4209bc27027aSMiklos Szeredi if (error) 4210bc27027aSMiklos Szeredi goto out; 4211bc27027aSMiklos Szeredi 4212da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42131da177e4SLinus Torvalds if (is_dir) 4214bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4215bc27027aSMiklos Szeredi dont_mount(new_dentry); 42168ed936b5SEric W. Biederman detach_mounts(new_dentry); 4217bc27027aSMiklos Szeredi } 4218da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4219da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4220bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4221da1ce067SMiklos Szeredi else 4222da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4223da1ce067SMiklos Szeredi } 4224bc27027aSMiklos Szeredi out: 4225da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4226bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4227bc27027aSMiklos Szeredi else if (target) 4228bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4229bc27027aSMiklos Szeredi dput(new_dentry); 4230da1ce067SMiklos Szeredi if (!error) { 4231123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4232da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4233da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4234da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4235da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4236da1ce067SMiklos Szeredi } 4237da1ce067SMiklos Szeredi } 42380eeca283SRobert Love fsnotify_oldname_free(old_name); 42390eeca283SRobert Love 42401da177e4SLinus Torvalds return error; 42411da177e4SLinus Torvalds } 42424d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42431da177e4SLinus Torvalds 4244520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4245520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42461da177e4SLinus Torvalds { 42471da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42481da177e4SLinus Torvalds struct dentry *trap; 4249f5beed75SAl Viro struct path old_path, new_path; 4250f5beed75SAl Viro struct qstr old_last, new_last; 4251f5beed75SAl Viro int old_type, new_type; 42528e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 425391a27b2aSJeff Layton struct filename *from; 425491a27b2aSJeff Layton struct filename *to; 4255f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4256c6a94284SJeff Layton bool should_retry = false; 42572ad94ae6SAl Viro int error; 4258520c8b16SMiklos Szeredi 42590d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4260da1ce067SMiklos Szeredi return -EINVAL; 4261da1ce067SMiklos Szeredi 42620d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42630d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4264520c8b16SMiklos Szeredi return -EINVAL; 4265520c8b16SMiklos Szeredi 42660d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42670d7a8555SMiklos Szeredi return -EPERM; 42680d7a8555SMiklos Szeredi 4269f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4270f5beed75SAl Viro target_flags = 0; 4271f5beed75SAl Viro 4272c6a94284SJeff Layton retry: 4273f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4274f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 427591a27b2aSJeff Layton if (IS_ERR(from)) { 427691a27b2aSJeff Layton error = PTR_ERR(from); 42771da177e4SLinus Torvalds goto exit; 427891a27b2aSJeff Layton } 42791da177e4SLinus Torvalds 4280f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4281f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 428291a27b2aSJeff Layton if (IS_ERR(to)) { 428391a27b2aSJeff Layton error = PTR_ERR(to); 42841da177e4SLinus Torvalds goto exit1; 428591a27b2aSJeff Layton } 42861da177e4SLinus Torvalds 42871da177e4SLinus Torvalds error = -EXDEV; 4288f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 42891da177e4SLinus Torvalds goto exit2; 42901da177e4SLinus Torvalds 42911da177e4SLinus Torvalds error = -EBUSY; 4292f5beed75SAl Viro if (old_type != LAST_NORM) 42931da177e4SLinus Torvalds goto exit2; 42941da177e4SLinus Torvalds 42950a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 42960a7c3937SMiklos Szeredi error = -EEXIST; 4297f5beed75SAl Viro if (new_type != LAST_NORM) 42981da177e4SLinus Torvalds goto exit2; 42991da177e4SLinus Torvalds 4300f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4301c30dabfeSJan Kara if (error) 4302c30dabfeSJan Kara goto exit2; 4303c30dabfeSJan Kara 43048e6d782cSJ. Bruce Fields retry_deleg: 4305f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43061da177e4SLinus Torvalds 4307f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43081da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43091da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43101da177e4SLinus Torvalds goto exit3; 43111da177e4SLinus Torvalds /* source must exist */ 43121da177e4SLinus Torvalds error = -ENOENT; 4313b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43141da177e4SLinus Torvalds goto exit4; 4315f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43161da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43171da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43181da177e4SLinus Torvalds goto exit4; 43190a7c3937SMiklos Szeredi error = -EEXIST; 43200a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43210a7c3937SMiklos Szeredi goto exit5; 4322da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4323da1ce067SMiklos Szeredi error = -ENOENT; 4324da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4325da1ce067SMiklos Szeredi goto exit5; 4326da1ce067SMiklos Szeredi 4327da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4328da1ce067SMiklos Szeredi error = -ENOTDIR; 4329f5beed75SAl Viro if (new_last.name[new_last.len]) 4330da1ce067SMiklos Szeredi goto exit5; 4331da1ce067SMiklos Szeredi } 4332da1ce067SMiklos Szeredi } 43330a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43340a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43350a7c3937SMiklos Szeredi error = -ENOTDIR; 4336f5beed75SAl Viro if (old_last.name[old_last.len]) 43370a7c3937SMiklos Szeredi goto exit5; 4338f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43390a7c3937SMiklos Szeredi goto exit5; 43400a7c3937SMiklos Szeredi } 43410a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43420a7c3937SMiklos Szeredi error = -EINVAL; 43430a7c3937SMiklos Szeredi if (old_dentry == trap) 43440a7c3937SMiklos Szeredi goto exit5; 43451da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4346da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43471da177e4SLinus Torvalds error = -ENOTEMPTY; 43481da177e4SLinus Torvalds if (new_dentry == trap) 43491da177e4SLinus Torvalds goto exit5; 43501da177e4SLinus Torvalds 4351f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4352f5beed75SAl Viro &new_path, new_dentry, flags); 4353be6d3e56SKentaro Takeda if (error) 4354c30dabfeSJan Kara goto exit5; 4355f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4356f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4357520c8b16SMiklos Szeredi &delegated_inode, flags); 43581da177e4SLinus Torvalds exit5: 43591da177e4SLinus Torvalds dput(new_dentry); 43601da177e4SLinus Torvalds exit4: 43611da177e4SLinus Torvalds dput(old_dentry); 43621da177e4SLinus Torvalds exit3: 4363f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 43648e6d782cSJ. Bruce Fields if (delegated_inode) { 43658e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43668e6d782cSJ. Bruce Fields if (!error) 43678e6d782cSJ. Bruce Fields goto retry_deleg; 43688e6d782cSJ. Bruce Fields } 4369f5beed75SAl Viro mnt_drop_write(old_path.mnt); 43701da177e4SLinus Torvalds exit2: 4371c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4372c6a94284SJeff Layton should_retry = true; 4373f5beed75SAl Viro path_put(&new_path); 43742ad94ae6SAl Viro putname(to); 43751da177e4SLinus Torvalds exit1: 4376f5beed75SAl Viro path_put(&old_path); 43771da177e4SLinus Torvalds putname(from); 4378c6a94284SJeff Layton if (should_retry) { 4379c6a94284SJeff Layton should_retry = false; 4380c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4381c6a94284SJeff Layton goto retry; 4382c6a94284SJeff Layton } 43832ad94ae6SAl Viro exit: 43841da177e4SLinus Torvalds return error; 43851da177e4SLinus Torvalds } 43861da177e4SLinus Torvalds 4387520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4388520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4389520c8b16SMiklos Szeredi { 4390520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4391520c8b16SMiklos Szeredi } 4392520c8b16SMiklos Szeredi 4393a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 43945590ff0dSUlrich Drepper { 4395520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 43965590ff0dSUlrich Drepper } 43975590ff0dSUlrich Drepper 4398787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4399787fb6bcSMiklos Szeredi { 4400787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4401787fb6bcSMiklos Szeredi if (error) 4402787fb6bcSMiklos Szeredi return error; 4403787fb6bcSMiklos Szeredi 4404787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4405787fb6bcSMiklos Szeredi return -EPERM; 4406787fb6bcSMiklos Szeredi 4407787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4408787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4409787fb6bcSMiklos Szeredi } 4410787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4411787fb6bcSMiklos Szeredi 44125d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44131da177e4SLinus Torvalds { 44145d826c84SAl Viro int len = PTR_ERR(link); 44151da177e4SLinus Torvalds if (IS_ERR(link)) 44161da177e4SLinus Torvalds goto out; 44171da177e4SLinus Torvalds 44181da177e4SLinus Torvalds len = strlen(link); 44191da177e4SLinus Torvalds if (len > (unsigned) buflen) 44201da177e4SLinus Torvalds len = buflen; 44211da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44221da177e4SLinus Torvalds len = -EFAULT; 44231da177e4SLinus Torvalds out: 44241da177e4SLinus Torvalds return len; 44251da177e4SLinus Torvalds } 44265d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44271da177e4SLinus Torvalds 44281da177e4SLinus Torvalds /* 44291da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44301da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44311da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44321da177e4SLinus Torvalds */ 44331da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44341da177e4SLinus Torvalds { 4435cc314eefSLinus Torvalds void *cookie; 4436d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4437694a1764SMarcin Slusarz int res; 4438cc314eefSLinus Torvalds 4439d4dee48bSAl Viro if (!link) { 44406e77137bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie); 4441680baacbSAl Viro if (IS_ERR(link)) 4442680baacbSAl Viro return PTR_ERR(link); 4443d4dee48bSAl Viro } 4444680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 44456e77137bSAl Viro if (dentry->d_inode->i_op->put_link) 4446680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4447694a1764SMarcin Slusarz return res; 44481da177e4SLinus Torvalds } 44494d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44501da177e4SLinus Torvalds 44511da177e4SLinus Torvalds /* get the link contents into pagecache */ 44521da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44531da177e4SLinus Torvalds { 4454ebd09abbSDuane Griffin char *kaddr; 44551da177e4SLinus Torvalds struct page *page; 44561da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4457090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44581da177e4SLinus Torvalds if (IS_ERR(page)) 44596fe6900eSNick Piggin return (char*)page; 44601da177e4SLinus Torvalds *ppage = page; 4461ebd09abbSDuane Griffin kaddr = kmap(page); 4462ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4463ebd09abbSDuane Griffin return kaddr; 44641da177e4SLinus Torvalds } 44651da177e4SLinus Torvalds 44661da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44671da177e4SLinus Torvalds { 44681da177e4SLinus Torvalds struct page *page = NULL; 44695d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44701da177e4SLinus Torvalds if (page) { 44711da177e4SLinus Torvalds kunmap(page); 44721da177e4SLinus Torvalds page_cache_release(page); 44731da177e4SLinus Torvalds } 44741da177e4SLinus Torvalds return res; 44751da177e4SLinus Torvalds } 44764d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44771da177e4SLinus Torvalds 44786e77137bSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie) 44791da177e4SLinus Torvalds { 4480cc314eefSLinus Torvalds struct page *page = NULL; 4481680baacbSAl Viro char *res = page_getlink(dentry, &page); 4482680baacbSAl Viro if (!IS_ERR(res)) 4483680baacbSAl Viro *cookie = page; 4484680baacbSAl Viro return res; 44851da177e4SLinus Torvalds } 44864d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 44871da177e4SLinus Torvalds 4488680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 44891da177e4SLinus Torvalds { 4490cc314eefSLinus Torvalds struct page *page = cookie; 44911da177e4SLinus Torvalds kunmap(page); 44921da177e4SLinus Torvalds page_cache_release(page); 44931da177e4SLinus Torvalds } 44944d359507SAl Viro EXPORT_SYMBOL(page_put_link); 44951da177e4SLinus Torvalds 449654566b2cSNick Piggin /* 449754566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 449854566b2cSNick Piggin */ 449954566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45001da177e4SLinus Torvalds { 45011da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45020adb25d2SKirill Korotaev struct page *page; 4503afddba49SNick Piggin void *fsdata; 4504beb497abSDmitriy Monakhov int err; 45051da177e4SLinus Torvalds char *kaddr; 450654566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 450754566b2cSNick Piggin if (nofs) 450854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45091da177e4SLinus Torvalds 45107e53cac4SNeilBrown retry: 4511afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 451254566b2cSNick Piggin flags, &page, &fsdata); 45131da177e4SLinus Torvalds if (err) 4514afddba49SNick Piggin goto fail; 4515afddba49SNick Piggin 4516e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45171da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4518e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4519afddba49SNick Piggin 4520afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4521afddba49SNick Piggin page, fsdata); 45221da177e4SLinus Torvalds if (err < 0) 45231da177e4SLinus Torvalds goto fail; 4524afddba49SNick Piggin if (err < len-1) 4525afddba49SNick Piggin goto retry; 4526afddba49SNick Piggin 45271da177e4SLinus Torvalds mark_inode_dirty(inode); 45281da177e4SLinus Torvalds return 0; 45291da177e4SLinus Torvalds fail: 45301da177e4SLinus Torvalds return err; 45311da177e4SLinus Torvalds } 45324d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45331da177e4SLinus Torvalds 45340adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45350adb25d2SKirill Korotaev { 45360adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 453754566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45380adb25d2SKirill Korotaev } 45394d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45400adb25d2SKirill Korotaev 454192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45421da177e4SLinus Torvalds .readlink = generic_readlink, 45431da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45441da177e4SLinus Torvalds .put_link = page_put_link, 45451da177e4SLinus Torvalds }; 45461da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4547