1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22508518549SPaul Moore struct filename *tmp; 22608518549SPaul Moore 22708518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22808518549SPaul Moore if (unlikely(!tmp)) { 22908518549SPaul Moore __putname(result); 23008518549SPaul Moore return ERR_PTR(-ENOMEM); 23108518549SPaul Moore } 23208518549SPaul Moore tmp->name = (char *)result; 23308518549SPaul Moore result = tmp; 23408518549SPaul Moore } else { 23508518549SPaul Moore __putname(result); 23608518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23708518549SPaul Moore } 23808518549SPaul Moore memcpy((char *)result->name, filename, len); 239c4ad8f98SLinus Torvalds result->uptr = NULL; 240c4ad8f98SLinus Torvalds result->aname = NULL; 24155422d0bSPaul Moore result->refcnt = 1; 242fd3522fdSPaul Moore audit_getname(result); 243c4ad8f98SLinus Torvalds 244c4ad8f98SLinus Torvalds return result; 245c4ad8f98SLinus Torvalds } 246c4ad8f98SLinus Torvalds 24791a27b2aSJeff Layton void putname(struct filename *name) 2481da177e4SLinus Torvalds { 24955422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25055422d0bSPaul Moore 25155422d0bSPaul Moore if (--name->refcnt > 0) 25255422d0bSPaul Moore return; 25355422d0bSPaul Moore 254fd2f7cb5SAl Viro if (name->name != name->iname) { 25555422d0bSPaul Moore __putname(name->name); 25655422d0bSPaul Moore kfree(name); 25755422d0bSPaul Moore } else 25855422d0bSPaul Moore __putname(name); 2591da177e4SLinus Torvalds } 2601da177e4SLinus Torvalds 261e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 262e77819e5SLinus Torvalds { 26384635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 264e77819e5SLinus Torvalds struct posix_acl *acl; 265e77819e5SLinus Torvalds 266e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2673567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2683567866bSAl Viro if (!acl) 269e77819e5SLinus Torvalds return -EAGAIN; 2703567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 271b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 272e77819e5SLinus Torvalds return -ECHILD; 273206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 274e77819e5SLinus Torvalds } 275e77819e5SLinus Torvalds 2762982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2774e34e719SChristoph Hellwig if (IS_ERR(acl)) 2784e34e719SChristoph Hellwig return PTR_ERR(acl); 279e77819e5SLinus Torvalds if (acl) { 280e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 281e77819e5SLinus Torvalds posix_acl_release(acl); 282e77819e5SLinus Torvalds return error; 283e77819e5SLinus Torvalds } 28484635d68SLinus Torvalds #endif 285e77819e5SLinus Torvalds 286e77819e5SLinus Torvalds return -EAGAIN; 287e77819e5SLinus Torvalds } 288e77819e5SLinus Torvalds 2895909ccaaSLinus Torvalds /* 290948409c7SAndreas Gruenbacher * This does the basic permission checking 2915909ccaaSLinus Torvalds */ 2927e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2935909ccaaSLinus Torvalds { 29426cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2955909ccaaSLinus Torvalds 2968e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2975909ccaaSLinus Torvalds mode >>= 6; 2985909ccaaSLinus Torvalds else { 299e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3007e40145eSAl Viro int error = check_acl(inode, mask); 3015909ccaaSLinus Torvalds if (error != -EAGAIN) 3025909ccaaSLinus Torvalds return error; 3035909ccaaSLinus Torvalds } 3045909ccaaSLinus Torvalds 3055909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3065909ccaaSLinus Torvalds mode >>= 3; 3075909ccaaSLinus Torvalds } 3085909ccaaSLinus Torvalds 3095909ccaaSLinus Torvalds /* 3105909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3115909ccaaSLinus Torvalds */ 3129c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3135909ccaaSLinus Torvalds return 0; 3145909ccaaSLinus Torvalds return -EACCES; 3155909ccaaSLinus Torvalds } 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds /** 3181da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3191da177e4SLinus Torvalds * @inode: inode to check access rights for 3208fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3211da177e4SLinus Torvalds * 3221da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3231da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3241da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 325b74c79e9SNick Piggin * are used for other things. 326b74c79e9SNick Piggin * 327b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 328b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 329b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3301da177e4SLinus Torvalds */ 3312830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3321da177e4SLinus Torvalds { 3335909ccaaSLinus Torvalds int ret; 3341da177e4SLinus Torvalds 3351da177e4SLinus Torvalds /* 336948409c7SAndreas Gruenbacher * Do the basic permission checks. 3371da177e4SLinus Torvalds */ 3387e40145eSAl Viro ret = acl_permission_check(inode, mask); 3395909ccaaSLinus Torvalds if (ret != -EACCES) 3405909ccaaSLinus Torvalds return ret; 3411da177e4SLinus Torvalds 342d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 343d594e7ecSAl Viro /* DACs are overridable for directories */ 344d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34623adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 347d594e7ecSAl Viro return 0; 34823adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3491da177e4SLinus Torvalds return 0; 3502a4c2242SStephen Smalley return -EACCES; 3512a4c2242SStephen Smalley } 3521da177e4SLinus Torvalds 3531da177e4SLinus Torvalds /* 3541da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3551da177e4SLinus Torvalds */ 3567ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 357d594e7ecSAl Viro if (mask == MAY_READ) 35823adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3591da177e4SLinus Torvalds return 0; 3602a4c2242SStephen Smalley /* 3612a4c2242SStephen Smalley * Read/write DACs are always overridable. 3622a4c2242SStephen Smalley * Executable DACs are overridable when there is 3632a4c2242SStephen Smalley * at least one exec bit set. 3642a4c2242SStephen Smalley */ 3652a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3662a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3672a4c2242SStephen Smalley return 0; 3681da177e4SLinus Torvalds 3691da177e4SLinus Torvalds return -EACCES; 3701da177e4SLinus Torvalds } 3714d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3721da177e4SLinus Torvalds 3733ddcd056SLinus Torvalds /* 3743ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3753ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3763ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3773ddcd056SLinus Torvalds * permission function, use the fast case". 3783ddcd056SLinus Torvalds */ 3793ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3803ddcd056SLinus Torvalds { 3813ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3823ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3833ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3843ddcd056SLinus Torvalds 3853ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3863ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3873ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3883ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3893ddcd056SLinus Torvalds } 3903ddcd056SLinus Torvalds return generic_permission(inode, mask); 3913ddcd056SLinus Torvalds } 3923ddcd056SLinus Torvalds 393cb23beb5SChristoph Hellwig /** 3940bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3950bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39655852635SRandy Dunlap * @inode: Inode to check permission on 3970bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4000bdaea90SDavid Howells */ 4010bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4020bdaea90SDavid Howells { 4030bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4040bdaea90SDavid Howells umode_t mode = inode->i_mode; 4050bdaea90SDavid Howells 4060bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 407bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4080bdaea90SDavid Howells return -EROFS; 4090bdaea90SDavid Howells } 4100bdaea90SDavid Howells return 0; 4110bdaea90SDavid Howells } 4120bdaea90SDavid Howells 4130bdaea90SDavid Howells /** 4140bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4150bdaea90SDavid Howells * @inode: Inode to check permission on 4160bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4170bdaea90SDavid Howells * 4180bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4190bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4200bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4210bdaea90SDavid Howells * 4220bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4230bdaea90SDavid Howells */ 4240bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4250bdaea90SDavid Howells { 4260bdaea90SDavid Howells int retval; 4270bdaea90SDavid Howells 4280bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4290bdaea90SDavid Howells if (retval) 4300bdaea90SDavid Howells return retval; 4314bfd054aSEric Biggers 4324bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4334bfd054aSEric Biggers /* 4344bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4354bfd054aSEric Biggers */ 4364bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4374bfd054aSEric Biggers return -EPERM; 4384bfd054aSEric Biggers 4394bfd054aSEric Biggers /* 4404bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4414bfd054aSEric Biggers * written back improperly if their true value is unknown 4424bfd054aSEric Biggers * to the vfs. 4434bfd054aSEric Biggers */ 4444bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4454bfd054aSEric Biggers return -EACCES; 4464bfd054aSEric Biggers } 4474bfd054aSEric Biggers 4484bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4494bfd054aSEric Biggers if (retval) 4504bfd054aSEric Biggers return retval; 4514bfd054aSEric Biggers 4524bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4534bfd054aSEric Biggers if (retval) 4544bfd054aSEric Biggers return retval; 4554bfd054aSEric Biggers 4564bfd054aSEric Biggers return security_inode_permission(inode, mask); 4570bdaea90SDavid Howells } 4584d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4590bdaea90SDavid Howells 4600bdaea90SDavid Howells /** 4615dd784d0SJan Blunck * path_get - get a reference to a path 4625dd784d0SJan Blunck * @path: path to get the reference to 4635dd784d0SJan Blunck * 4645dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4655dd784d0SJan Blunck */ 466dcf787f3SAl Viro void path_get(const struct path *path) 4675dd784d0SJan Blunck { 4685dd784d0SJan Blunck mntget(path->mnt); 4695dd784d0SJan Blunck dget(path->dentry); 4705dd784d0SJan Blunck } 4715dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4725dd784d0SJan Blunck 4735dd784d0SJan Blunck /** 4741d957f9bSJan Blunck * path_put - put a reference to a path 4751d957f9bSJan Blunck * @path: path to put the reference to 4761d957f9bSJan Blunck * 4771d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4781d957f9bSJan Blunck */ 479dcf787f3SAl Viro void path_put(const struct path *path) 4801da177e4SLinus Torvalds { 4811d957f9bSJan Blunck dput(path->dentry); 4821d957f9bSJan Blunck mntput(path->mnt); 4831da177e4SLinus Torvalds } 4841d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4851da177e4SLinus Torvalds 486894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4871f55a6ecSAl Viro struct nameidata { 4881f55a6ecSAl Viro struct path path; 4891f55a6ecSAl Viro struct qstr last; 4901f55a6ecSAl Viro struct path root; 4911f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4921f55a6ecSAl Viro unsigned int flags; 4939883d185SAl Viro unsigned seq, m_seq; 4941f55a6ecSAl Viro int last_type; 4951f55a6ecSAl Viro unsigned depth; 496756daf26SNeilBrown int total_link_count; 497697fc6caSAl Viro struct saved { 498697fc6caSAl Viro struct path link; 499fceef393SAl Viro struct delayed_call done; 500697fc6caSAl Viro const char *name; 5010450b2d1SAl Viro unsigned seq; 502894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5039883d185SAl Viro struct filename *name; 5049883d185SAl Viro struct nameidata *saved; 505fceef393SAl Viro struct inode *link_inode; 5069883d185SAl Viro unsigned root_seq; 5079883d185SAl Viro int dfd; 5083859a271SKees Cook } __randomize_layout; 5091f55a6ecSAl Viro 5109883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 511894bc8c4SAl Viro { 512756daf26SNeilBrown struct nameidata *old = current->nameidata; 513756daf26SNeilBrown p->stack = p->internal; 514c8a53ee5SAl Viro p->dfd = dfd; 515c8a53ee5SAl Viro p->name = name; 516756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5179883d185SAl Viro p->saved = old; 518756daf26SNeilBrown current->nameidata = p; 519894bc8c4SAl Viro } 520894bc8c4SAl Viro 5219883d185SAl Viro static void restore_nameidata(void) 522894bc8c4SAl Viro { 5239883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 524756daf26SNeilBrown 525756daf26SNeilBrown current->nameidata = old; 526756daf26SNeilBrown if (old) 527756daf26SNeilBrown old->total_link_count = now->total_link_count; 528e1a63bbcSAl Viro if (now->stack != now->internal) 529756daf26SNeilBrown kfree(now->stack); 530894bc8c4SAl Viro } 531894bc8c4SAl Viro 532894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 533894bc8c4SAl Viro { 534bc40aee0SAl Viro struct saved *p; 535bc40aee0SAl Viro 536bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 537bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 538bc40aee0SAl Viro GFP_ATOMIC); 539bc40aee0SAl Viro if (unlikely(!p)) 540bc40aee0SAl Viro return -ECHILD; 541bc40aee0SAl Viro } else { 542bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 543894bc8c4SAl Viro GFP_KERNEL); 544894bc8c4SAl Viro if (unlikely(!p)) 545894bc8c4SAl Viro return -ENOMEM; 546bc40aee0SAl Viro } 547894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 548894bc8c4SAl Viro nd->stack = p; 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro } 551894bc8c4SAl Viro 552397d425dSEric W. Biederman /** 553397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 554397d425dSEric W. Biederman * @path: nameidate to verify 555397d425dSEric W. Biederman * 556397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 557397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 558397d425dSEric W. Biederman */ 559397d425dSEric W. Biederman static bool path_connected(const struct path *path) 560397d425dSEric W. Biederman { 561397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 562397d425dSEric W. Biederman 563397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 564397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 565397d425dSEric W. Biederman return true; 566397d425dSEric W. Biederman 567397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 568397d425dSEric W. Biederman } 569397d425dSEric W. Biederman 570894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 571894bc8c4SAl Viro { 572da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 573894bc8c4SAl Viro return 0; 574894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 575894bc8c4SAl Viro return 0; 576894bc8c4SAl Viro return __nd_alloc_stack(nd); 577894bc8c4SAl Viro } 578894bc8c4SAl Viro 5797973387aSAl Viro static void drop_links(struct nameidata *nd) 5807973387aSAl Viro { 5817973387aSAl Viro int i = nd->depth; 5827973387aSAl Viro while (i--) { 5837973387aSAl Viro struct saved *last = nd->stack + i; 584fceef393SAl Viro do_delayed_call(&last->done); 585fceef393SAl Viro clear_delayed_call(&last->done); 5867973387aSAl Viro } 5877973387aSAl Viro } 5887973387aSAl Viro 5897973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5907973387aSAl Viro { 5917973387aSAl Viro drop_links(nd); 5927973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5937973387aSAl Viro int i; 5947973387aSAl Viro path_put(&nd->path); 5957973387aSAl Viro for (i = 0; i < nd->depth; i++) 5967973387aSAl Viro path_put(&nd->stack[i].link); 597102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 598102b8af2SAl Viro path_put(&nd->root); 599102b8af2SAl Viro nd->root.mnt = NULL; 600102b8af2SAl Viro } 6017973387aSAl Viro } else { 6027973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6037973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6047973387aSAl Viro nd->root.mnt = NULL; 6057973387aSAl Viro rcu_read_unlock(); 6067973387aSAl Viro } 6077973387aSAl Viro nd->depth = 0; 6087973387aSAl Viro } 6097973387aSAl Viro 6107973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6117973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6127973387aSAl Viro struct path *path, unsigned seq) 6137973387aSAl Viro { 6147973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6157973387aSAl Viro if (unlikely(res)) { 6167973387aSAl Viro if (res > 0) 6177973387aSAl Viro path->mnt = NULL; 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6227973387aSAl Viro path->dentry = NULL; 6237973387aSAl Viro return false; 6247973387aSAl Viro } 6257973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6267973387aSAl Viro } 6277973387aSAl Viro 6287973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6297973387aSAl Viro { 6307973387aSAl Viro int i; 6317973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6327973387aSAl Viro struct saved *last = nd->stack + i; 6337973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6347973387aSAl Viro drop_links(nd); 6357973387aSAl Viro nd->depth = i + 1; 6367973387aSAl Viro return false; 6377973387aSAl Viro } 6387973387aSAl Viro } 6397973387aSAl Viro return true; 6407973387aSAl Viro } 6417973387aSAl Viro 64219660af7SAl Viro /* 64331e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 64419660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 64519660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 64657e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 64719660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 64819660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 64919660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 65019660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 65131e6b01fSNick Piggin */ 65231e6b01fSNick Piggin 65331e6b01fSNick Piggin /** 65419660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 65519660af7SAl Viro * @nd: nameidata pathwalk data 65639191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 65731e6b01fSNick Piggin * 6584675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6594675ac39SAl Viro * for ref-walk mode. 6604675ac39SAl Viro * Must be called from rcu-walk context. 6617973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6627973387aSAl Viro * terminate_walk(). 66331e6b01fSNick Piggin */ 6644675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 66531e6b01fSNick Piggin { 66631e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 66731e6b01fSNick Piggin 66831e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 669e5c832d5SLinus Torvalds 670e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6717973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6727973387aSAl Viro goto out2; 6734675ac39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 6744675ac39SAl Viro goto out1; 6754675ac39SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 6764675ac39SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) 6774675ac39SAl Viro goto out; 6784675ac39SAl Viro } 6794675ac39SAl Viro rcu_read_unlock(); 6804675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6814675ac39SAl Viro return 0; 6824675ac39SAl Viro 6834675ac39SAl Viro out2: 6844675ac39SAl Viro nd->path.mnt = NULL; 6854675ac39SAl Viro nd->path.dentry = NULL; 6864675ac39SAl Viro out1: 6874675ac39SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6884675ac39SAl Viro nd->root.mnt = NULL; 6894675ac39SAl Viro out: 6904675ac39SAl Viro rcu_read_unlock(); 6914675ac39SAl Viro return -ECHILD; 6924675ac39SAl Viro } 6934675ac39SAl Viro 6944675ac39SAl Viro /** 6954675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 6964675ac39SAl Viro * @nd: nameidata pathwalk data 6974675ac39SAl Viro * @dentry: child of nd->path.dentry 6984675ac39SAl Viro * @seq: seq number to check dentry against 6994675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7004675ac39SAl Viro * 7014675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7024675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7034675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7044675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7054675ac39SAl Viro * terminate_walk(). 7064675ac39SAl Viro */ 7074675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7084675ac39SAl Viro { 7094675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7104675ac39SAl Viro 7114675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7124675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7134675ac39SAl Viro goto out2; 7147973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7157973387aSAl Viro goto out2; 7164675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7177973387aSAl Viro goto out1; 71848a066e7SAl Viro 71915570086SLinus Torvalds /* 7204675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7214675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7224675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7234675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7244675ac39SAl Viro * know the parent must still be valid if the child sequence number is 72515570086SLinus Torvalds */ 7264675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 727e5c832d5SLinus Torvalds goto out; 7284675ac39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) { 7294675ac39SAl Viro rcu_read_unlock(); 7304675ac39SAl Viro dput(dentry); 7314675ac39SAl Viro goto drop_root_mnt; 73219660af7SAl Viro } 733e5c832d5SLinus Torvalds /* 734e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 735e5c832d5SLinus Torvalds * still valid and get it if required. 736e5c832d5SLinus Torvalds */ 737e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7385a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7395a8d87e8SAl Viro rcu_read_unlock(); 7405a8d87e8SAl Viro dput(dentry); 7415a8d87e8SAl Viro return -ECHILD; 7427973387aSAl Viro } 74331e6b01fSNick Piggin } 74431e6b01fSNick Piggin 7458b61e74fSAl Viro rcu_read_unlock(); 74631e6b01fSNick Piggin return 0; 74719660af7SAl Viro 7487973387aSAl Viro out2: 7497973387aSAl Viro nd->path.mnt = NULL; 7507973387aSAl Viro out1: 7517973387aSAl Viro nd->path.dentry = NULL; 752e5c832d5SLinus Torvalds out: 7538b61e74fSAl Viro rcu_read_unlock(); 754d0d27277SLinus Torvalds drop_root_mnt: 755d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 756d0d27277SLinus Torvalds nd->root.mnt = NULL; 75731e6b01fSNick Piggin return -ECHILD; 75831e6b01fSNick Piggin } 75931e6b01fSNick Piggin 7604ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76134286d66SNick Piggin { 762a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7634ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 764a89f8337SAl Viro else 765a89f8337SAl Viro return 1; 76634286d66SNick Piggin } 76734286d66SNick Piggin 7689f1fafeeSAl Viro /** 7699f1fafeeSAl Viro * complete_walk - successful completion of path walk 7709f1fafeeSAl Viro * @nd: pointer nameidata 77139159de2SJeff Layton * 7729f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7739f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7749f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7759f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7769f1fafeeSAl Viro * need to drop nd->path. 77739159de2SJeff Layton */ 7789f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77939159de2SJeff Layton { 78016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78139159de2SJeff Layton int status; 78239159de2SJeff Layton 7839f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7849f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7859f1fafeeSAl Viro nd->root.mnt = NULL; 7864675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 78748a066e7SAl Viro return -ECHILD; 78848a066e7SAl Viro } 7899f1fafeeSAl Viro 79016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79139159de2SJeff Layton return 0; 79239159de2SJeff Layton 793ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79416c2cd71SAl Viro return 0; 79516c2cd71SAl Viro 796ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79739159de2SJeff Layton if (status > 0) 79839159de2SJeff Layton return 0; 79939159de2SJeff Layton 80016c2cd71SAl Viro if (!status) 80139159de2SJeff Layton status = -ESTALE; 80216c2cd71SAl Viro 80339159de2SJeff Layton return status; 80439159de2SJeff Layton } 80539159de2SJeff Layton 80618d8c860SAl Viro static void set_root(struct nameidata *nd) 8072a737871SAl Viro { 80831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8099e6697e2SAl Viro 8109e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8118f47a016SAl Viro unsigned seq; 812c28cc364SNick Piggin 813c28cc364SNick Piggin do { 814c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81531e6b01fSNick Piggin nd->root = fs->root; 8168f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 817c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8189e6697e2SAl Viro } else { 8199e6697e2SAl Viro get_fs_root(fs, &nd->root); 8209e6697e2SAl Viro } 82131e6b01fSNick Piggin } 82231e6b01fSNick Piggin 8231d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 824051d3812SIan Kent { 825051d3812SIan Kent dput(path->dentry); 8264ac91378SJan Blunck if (path->mnt != nd->path.mnt) 827051d3812SIan Kent mntput(path->mnt); 828051d3812SIan Kent } 829051d3812SIan Kent 8307b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8317b9337aaSNick Piggin struct nameidata *nd) 832051d3812SIan Kent { 83331e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8344ac91378SJan Blunck dput(nd->path.dentry); 83531e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8364ac91378SJan Blunck mntput(nd->path.mnt); 8379a229683SHuang Shijie } 83831e6b01fSNick Piggin nd->path.mnt = path->mnt; 8394ac91378SJan Blunck nd->path.dentry = path->dentry; 840051d3812SIan Kent } 841051d3812SIan Kent 842248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 843248fb5b9SAl Viro { 844248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 845248fb5b9SAl Viro struct dentry *d; 846248fb5b9SAl Viro nd->path = nd->root; 847248fb5b9SAl Viro d = nd->path.dentry; 848248fb5b9SAl Viro nd->inode = d->d_inode; 849248fb5b9SAl Viro nd->seq = nd->root_seq; 850248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 851248fb5b9SAl Viro return -ECHILD; 852248fb5b9SAl Viro } else { 853248fb5b9SAl Viro path_put(&nd->path); 854248fb5b9SAl Viro nd->path = nd->root; 855248fb5b9SAl Viro path_get(&nd->path); 856248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 857248fb5b9SAl Viro } 858248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 859248fb5b9SAl Viro return 0; 860248fb5b9SAl Viro } 861248fb5b9SAl Viro 862b5fb63c1SChristoph Hellwig /* 8636b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 864b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 865b5fb63c1SChristoph Hellwig */ 8666e77137bSAl Viro void nd_jump_link(struct path *path) 867b5fb63c1SChristoph Hellwig { 8686e77137bSAl Viro struct nameidata *nd = current->nameidata; 869b5fb63c1SChristoph Hellwig path_put(&nd->path); 870b5fb63c1SChristoph Hellwig 871b5fb63c1SChristoph Hellwig nd->path = *path; 872b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 873b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 874b5fb63c1SChristoph Hellwig } 875b5fb63c1SChristoph Hellwig 876b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 877574197e0SAl Viro { 87821c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 879fceef393SAl Viro do_delayed_call(&last->done); 8806548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 881b9ff4429SAl Viro path_put(&last->link); 882574197e0SAl Viro } 883574197e0SAl Viro 884561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 885561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 886800179c9SKees Cook 887800179c9SKees Cook /** 888800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88955852635SRandy Dunlap * @nd: nameidata pathwalk data 890800179c9SKees Cook * 891800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 892800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 893800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 894800179c9SKees Cook * processes from failing races against path names that may change out 895800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 896800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 897800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 898800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 899800179c9SKees Cook * 900800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 901800179c9SKees Cook */ 902fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 903800179c9SKees Cook { 904800179c9SKees Cook const struct inode *inode; 905800179c9SKees Cook const struct inode *parent; 9062d7f9e2aSSeth Forshee kuid_t puid; 907800179c9SKees Cook 908800179c9SKees Cook if (!sysctl_protected_symlinks) 909800179c9SKees Cook return 0; 910800179c9SKees Cook 911800179c9SKees Cook /* Allowed if owner and follower match. */ 912fceef393SAl Viro inode = nd->link_inode; 91381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 914800179c9SKees Cook return 0; 915800179c9SKees Cook 916800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 917aa65fa35SAl Viro parent = nd->inode; 918800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 919800179c9SKees Cook return 0; 920800179c9SKees Cook 921800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9222d7f9e2aSSeth Forshee puid = parent->i_uid; 9232d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 924800179c9SKees Cook return 0; 925800179c9SKees Cook 92631956502SAl Viro if (nd->flags & LOOKUP_RCU) 92731956502SAl Viro return -ECHILD; 92831956502SAl Viro 9291cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 930800179c9SKees Cook return -EACCES; 931800179c9SKees Cook } 932800179c9SKees Cook 933800179c9SKees Cook /** 934800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 935800179c9SKees Cook * @inode: the source inode to hardlink from 936800179c9SKees Cook * 937800179c9SKees Cook * Return false if at least one of the following conditions: 938800179c9SKees Cook * - inode is not a regular file 939800179c9SKees Cook * - inode is setuid 940800179c9SKees Cook * - inode is setgid and group-exec 941800179c9SKees Cook * - access failure for read and write 942800179c9SKees Cook * 943800179c9SKees Cook * Otherwise returns true. 944800179c9SKees Cook */ 945800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 946800179c9SKees Cook { 947800179c9SKees Cook umode_t mode = inode->i_mode; 948800179c9SKees Cook 949800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 950800179c9SKees Cook if (!S_ISREG(mode)) 951800179c9SKees Cook return false; 952800179c9SKees Cook 953800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 954800179c9SKees Cook if (mode & S_ISUID) 955800179c9SKees Cook return false; 956800179c9SKees Cook 957800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 958800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 959800179c9SKees Cook return false; 960800179c9SKees Cook 961800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 962800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 963800179c9SKees Cook return false; 964800179c9SKees Cook 965800179c9SKees Cook return true; 966800179c9SKees Cook } 967800179c9SKees Cook 968800179c9SKees Cook /** 969800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 970800179c9SKees Cook * @link: the source to hardlink from 971800179c9SKees Cook * 972800179c9SKees Cook * Block hardlink when all of: 973800179c9SKees Cook * - sysctl_protected_hardlinks enabled 974800179c9SKees Cook * - fsuid does not match inode 975800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 976f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 977800179c9SKees Cook * 978800179c9SKees Cook * Returns 0 if successful, -ve on error. 979800179c9SKees Cook */ 980800179c9SKees Cook static int may_linkat(struct path *link) 981800179c9SKees Cook { 982800179c9SKees Cook struct inode *inode; 983800179c9SKees Cook 984800179c9SKees Cook if (!sysctl_protected_hardlinks) 985800179c9SKees Cook return 0; 986800179c9SKees Cook 987800179c9SKees Cook inode = link->dentry->d_inode; 988800179c9SKees Cook 989800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 990800179c9SKees Cook * otherwise, it must be a safe source. 991800179c9SKees Cook */ 992cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 993800179c9SKees Cook return 0; 994800179c9SKees Cook 995a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 996800179c9SKees Cook return -EPERM; 997800179c9SKees Cook } 998800179c9SKees Cook 9993b2e7f75SAl Viro static __always_inline 10003b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10011da177e4SLinus Torvalds { 1002ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10031cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1004fceef393SAl Viro struct inode *inode = nd->link_inode; 10056d7b5aaeSAl Viro int error; 10060a959df5SAl Viro const char *res; 10071da177e4SLinus Torvalds 10088fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10098fa9dd24SNeilBrown touch_atime(&last->link); 10108fa9dd24SNeilBrown cond_resched(); 1011598e3c8fSMiklos Szeredi } else if (atime_needs_update_rcu(&last->link, inode)) { 10124675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10138fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10148fa9dd24SNeilBrown touch_atime(&last->link); 10158fa9dd24SNeilBrown } 10168fa9dd24SNeilBrown 1017bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1018bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1019bda0be7aSNeilBrown if (unlikely(error)) 10206920a440SAl Viro return ERR_PTR(error); 102136f3b4f6SAl Viro 102286acdca1SAl Viro nd->last_type = LAST_BIND; 1023d4dee48bSAl Viro res = inode->i_link; 1024d4dee48bSAl Viro if (!res) { 1025fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1026fceef393SAl Viro struct delayed_call *); 1027fceef393SAl Viro get = inode->i_op->get_link; 10288c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1029fceef393SAl Viro res = get(NULL, inode, &last->done); 10306b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10314675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10328c1b4566SAl Viro return ERR_PTR(-ECHILD); 1033fceef393SAl Viro res = get(dentry, inode, &last->done); 10348c1b4566SAl Viro } 10356b255391SAl Viro } else { 1036fceef393SAl Viro res = get(dentry, inode, &last->done); 10376b255391SAl Viro } 1038fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1039fab51e8aSAl Viro return res; 10400a959df5SAl Viro } 1041fab51e8aSAl Viro if (*res == '/') { 1042fab51e8aSAl Viro if (!nd->root.mnt) 1043fab51e8aSAl Viro set_root(nd); 1044248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1045fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1046fab51e8aSAl Viro while (unlikely(*++res == '/')) 1047fab51e8aSAl Viro ; 1048fab51e8aSAl Viro } 1049fab51e8aSAl Viro if (!*res) 1050fab51e8aSAl Viro res = NULL; 10510a959df5SAl Viro return res; 10520a959df5SAl Viro } 10536d7b5aaeSAl Viro 1054f015f126SDavid Howells /* 1055f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1056f015f126SDavid Howells * 1057f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1058f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1059f015f126SDavid Howells * Up is towards /. 1060f015f126SDavid Howells * 1061f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1062f015f126SDavid Howells * root. 1063f015f126SDavid Howells */ 1064bab77ebfSAl Viro int follow_up(struct path *path) 10651da177e4SLinus Torvalds { 10660714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10670714a533SAl Viro struct mount *parent; 10681da177e4SLinus Torvalds struct dentry *mountpoint; 106999b7db7bSNick Piggin 107048a066e7SAl Viro read_seqlock_excl(&mount_lock); 10710714a533SAl Viro parent = mnt->mnt_parent; 10723c0a6163SAl Viro if (parent == mnt) { 107348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10741da177e4SLinus Torvalds return 0; 10751da177e4SLinus Torvalds } 10760714a533SAl Viro mntget(&parent->mnt); 1077a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1079bab77ebfSAl Viro dput(path->dentry); 1080bab77ebfSAl Viro path->dentry = mountpoint; 1081bab77ebfSAl Viro mntput(path->mnt); 10820714a533SAl Viro path->mnt = &parent->mnt; 10831da177e4SLinus Torvalds return 1; 10841da177e4SLinus Torvalds } 10854d359507SAl Viro EXPORT_SYMBOL(follow_up); 10861da177e4SLinus Torvalds 1087b5c84bf6SNick Piggin /* 10889875cf80SDavid Howells * Perform an automount 10899875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10909875cf80SDavid Howells * were called with. 10911da177e4SLinus Torvalds */ 1092756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10939875cf80SDavid Howells bool *need_mntput) 109431e6b01fSNick Piggin { 10959875cf80SDavid Howells struct vfsmount *mnt; 1096ea5b778aSDavid Howells int err; 10979875cf80SDavid Howells 10989875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 10999875cf80SDavid Howells return -EREMOTE; 11009875cf80SDavid Howells 11010ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11020ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11030ec26fd0SMiklos Szeredi * the name. 11040ec26fd0SMiklos Szeredi * 11050ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11065a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11070ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11080ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11090ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11100ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11115a30d8a2SDavid Howells */ 1112756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 111342f46148SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | 111442f46148SIan Kent LOOKUP_AUTOMOUNT))) { 111542f46148SIan Kent /* Positive dentry that isn't meant to trigger an 111642f46148SIan Kent * automount, EISDIR will allow it to be used, 111742f46148SIan Kent * otherwise there's no mount here "now" so return 111842f46148SIan Kent * ENOENT. 111942f46148SIan Kent */ 112042f46148SIan Kent if (path->dentry->d_inode) 11219875cf80SDavid Howells return -EISDIR; 112242f46148SIan Kent else 112342f46148SIan Kent return -ENOENT; 112442f46148SIan Kent } 11250ec26fd0SMiklos Szeredi 1126aeaa4a79SEric W. Biederman if (path->dentry->d_sb->s_user_ns != &init_user_ns) 1127aeaa4a79SEric W. Biederman return -EACCES; 1128aeaa4a79SEric W. Biederman 1129756daf26SNeilBrown nd->total_link_count++; 1130756daf26SNeilBrown if (nd->total_link_count >= 40) 11319875cf80SDavid Howells return -ELOOP; 11329875cf80SDavid Howells 11339875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11349875cf80SDavid Howells if (IS_ERR(mnt)) { 11359875cf80SDavid Howells /* 11369875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11379875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11389875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11399875cf80SDavid Howells * 11409875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11419875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11429875cf80SDavid Howells * the path is inaccessible and we should say so. 11439875cf80SDavid Howells */ 1144756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11459875cf80SDavid Howells return -EREMOTE; 11469875cf80SDavid Howells return PTR_ERR(mnt); 114731e6b01fSNick Piggin } 1148ea5b778aSDavid Howells 11499875cf80SDavid Howells if (!mnt) /* mount collision */ 11509875cf80SDavid Howells return 0; 11519875cf80SDavid Howells 11528aef1884SAl Viro if (!*need_mntput) { 11538aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11548aef1884SAl Viro mntget(path->mnt); 11558aef1884SAl Viro *need_mntput = true; 11568aef1884SAl Viro } 115719a167afSAl Viro err = finish_automount(mnt, path); 1158ea5b778aSDavid Howells 1159ea5b778aSDavid Howells switch (err) { 1160ea5b778aSDavid Howells case -EBUSY: 1161ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 116219a167afSAl Viro return 0; 1163ea5b778aSDavid Howells case 0: 11648aef1884SAl Viro path_put(path); 11659875cf80SDavid Howells path->mnt = mnt; 11669875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11679875cf80SDavid Howells return 0; 116819a167afSAl Viro default: 116919a167afSAl Viro return err; 11709875cf80SDavid Howells } 117119a167afSAl Viro 1172ea5b778aSDavid Howells } 11739875cf80SDavid Howells 11749875cf80SDavid Howells /* 11759875cf80SDavid Howells * Handle a dentry that is managed in some way. 1176cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11779875cf80SDavid Howells * - Flagged as mountpoint 11789875cf80SDavid Howells * - Flagged as automount point 11799875cf80SDavid Howells * 11809875cf80SDavid Howells * This may only be called in refwalk mode. 11819875cf80SDavid Howells * 11829875cf80SDavid Howells * Serialization is taken care of in namespace.c 11839875cf80SDavid Howells */ 1184756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11859875cf80SDavid Howells { 11868aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11879875cf80SDavid Howells unsigned managed; 11889875cf80SDavid Howells bool need_mntput = false; 11898aef1884SAl Viro int ret = 0; 11909875cf80SDavid Howells 11919875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11929875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11939875cf80SDavid Howells * the components of that value change under us */ 11946aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 11959875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11969875cf80SDavid Howells unlikely(managed != 0)) { 1197cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1198cc53ce53SDavid Howells * being held. */ 1199cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1200cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1201cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1202fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1203cc53ce53SDavid Howells if (ret < 0) 12048aef1884SAl Viro break; 1205cc53ce53SDavid Howells } 1206cc53ce53SDavid Howells 12079875cf80SDavid Howells /* Transit to a mounted filesystem. */ 12089875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 12099875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12109875cf80SDavid Howells if (mounted) { 12119875cf80SDavid Howells dput(path->dentry); 12129875cf80SDavid Howells if (need_mntput) 1213463ffb2eSAl Viro mntput(path->mnt); 1214463ffb2eSAl Viro path->mnt = mounted; 1215463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12169875cf80SDavid Howells need_mntput = true; 12179875cf80SDavid Howells continue; 1218463ffb2eSAl Viro } 1219463ffb2eSAl Viro 12209875cf80SDavid Howells /* Something is mounted on this dentry in another 12219875cf80SDavid Howells * namespace and/or whatever was mounted there in this 122248a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 122348a066e7SAl Viro * get it */ 12241da177e4SLinus Torvalds } 12259875cf80SDavid Howells 12269875cf80SDavid Howells /* Handle an automount point */ 12279875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1228756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12299875cf80SDavid Howells if (ret < 0) 12308aef1884SAl Viro break; 12319875cf80SDavid Howells continue; 12329875cf80SDavid Howells } 12339875cf80SDavid Howells 12349875cf80SDavid Howells /* We didn't change the current path point */ 12359875cf80SDavid Howells break; 12369875cf80SDavid Howells } 12378aef1884SAl Viro 12388aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12398aef1884SAl Viro mntput(path->mnt); 1240e9742b53SAl Viro if (ret == -EISDIR || !ret) 1241e9742b53SAl Viro ret = 1; 12428402752eSAl Viro if (need_mntput) 12438402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12448402752eSAl Viro if (unlikely(ret < 0)) 12458402752eSAl Viro path_put_conditional(path, nd); 12468402752eSAl Viro return ret; 12471da177e4SLinus Torvalds } 12481da177e4SLinus Torvalds 1249cc53ce53SDavid Howells int follow_down_one(struct path *path) 12501da177e4SLinus Torvalds { 12511da177e4SLinus Torvalds struct vfsmount *mounted; 12521da177e4SLinus Torvalds 12531c755af4SAl Viro mounted = lookup_mnt(path); 12541da177e4SLinus Torvalds if (mounted) { 12559393bd07SAl Viro dput(path->dentry); 12569393bd07SAl Viro mntput(path->mnt); 12579393bd07SAl Viro path->mnt = mounted; 12589393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12591da177e4SLinus Torvalds return 1; 12601da177e4SLinus Torvalds } 12611da177e4SLinus Torvalds return 0; 12621da177e4SLinus Torvalds } 12634d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12641da177e4SLinus Torvalds 1265fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 126662a7375eSIan Kent { 1267fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1268fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 126962a7375eSIan Kent } 127062a7375eSIan Kent 12719875cf80SDavid Howells /* 1272287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1273287548e4SAl Viro * we meet a managed dentry that would need blocking. 12749875cf80SDavid Howells */ 12759875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1276254cf582SAl Viro struct inode **inode, unsigned *seqp) 12779875cf80SDavid Howells { 127862a7375eSIan Kent for (;;) { 1279c7105365SAl Viro struct mount *mounted; 128062a7375eSIan Kent /* 128162a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 128262a7375eSIan Kent * that wants to block transit. 128362a7375eSIan Kent */ 1284fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1285b8faf035SNeilBrown case -ECHILD: 1286b8faf035SNeilBrown default: 1287ab90911fSDavid Howells return false; 1288b8faf035SNeilBrown case -EISDIR: 1289b8faf035SNeilBrown return true; 1290b8faf035SNeilBrown case 0: 1291b8faf035SNeilBrown break; 1292b8faf035SNeilBrown } 129362a7375eSIan Kent 129462a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1295b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 129662a7375eSIan Kent 1297474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12989875cf80SDavid Howells if (!mounted) 12999875cf80SDavid Howells break; 1300c7105365SAl Viro path->mnt = &mounted->mnt; 1301c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1302a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1303254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 130459430262SLinus Torvalds /* 130559430262SLinus Torvalds * Update the inode too. We don't need to re-check the 130659430262SLinus Torvalds * dentry sequence number here after this d_inode read, 130759430262SLinus Torvalds * because a mount-point is always pinned. 130859430262SLinus Torvalds */ 130959430262SLinus Torvalds *inode = path->dentry->d_inode; 13109875cf80SDavid Howells } 1311f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1312b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1313287548e4SAl Viro } 1314287548e4SAl Viro 131531e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 131631e6b01fSNick Piggin { 13174023bfc9SAl Viro struct inode *inode = nd->inode; 131831e6b01fSNick Piggin 131931e6b01fSNick Piggin while (1) { 1320aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 132131e6b01fSNick Piggin break; 132231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 132331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 132431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 132531e6b01fSNick Piggin unsigned seq; 132631e6b01fSNick Piggin 13274023bfc9SAl Viro inode = parent->d_inode; 132831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1329aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1330aed434adSAl Viro return -ECHILD; 133131e6b01fSNick Piggin nd->path.dentry = parent; 133231e6b01fSNick Piggin nd->seq = seq; 1333397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1334397d425dSEric W. Biederman return -ENOENT; 133531e6b01fSNick Piggin break; 1336aed434adSAl Viro } else { 1337aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1338aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1339aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1340aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1341aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1342aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1343aed434adSAl Viro return -ECHILD; 1344aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 134531e6b01fSNick Piggin break; 1346aed434adSAl Viro /* we know that mountpoint was pinned */ 1347aed434adSAl Viro nd->path.dentry = mountpoint; 1348aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1349aed434adSAl Viro inode = inode2; 1350aed434adSAl Viro nd->seq = seq; 135131e6b01fSNick Piggin } 1352aed434adSAl Viro } 1353aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1354b37199e6SAl Viro struct mount *mounted; 1355b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1356aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1357aed434adSAl Viro return -ECHILD; 1358b37199e6SAl Viro if (!mounted) 1359b37199e6SAl Viro break; 1360b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1361b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13624023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1363b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1364b37199e6SAl Viro } 13654023bfc9SAl Viro nd->inode = inode; 136631e6b01fSNick Piggin return 0; 136731e6b01fSNick Piggin } 136831e6b01fSNick Piggin 13699875cf80SDavid Howells /* 1370cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1371cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1372cc53ce53SDavid Howells * caller is permitted to proceed or not. 1373cc53ce53SDavid Howells */ 13747cc90cc3SAl Viro int follow_down(struct path *path) 1375cc53ce53SDavid Howells { 1376cc53ce53SDavid Howells unsigned managed; 1377cc53ce53SDavid Howells int ret; 1378cc53ce53SDavid Howells 13796aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1380cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1381cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1382cc53ce53SDavid Howells * being held. 1383cc53ce53SDavid Howells * 1384cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1385cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1386cc53ce53SDavid Howells * other than its daemon the right to mount on its 1387cc53ce53SDavid Howells * superstructure. 1388cc53ce53SDavid Howells * 1389cc53ce53SDavid Howells * The filesystem may sleep at this point. 1390cc53ce53SDavid Howells */ 1391cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1392cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1393cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1394fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1395cc53ce53SDavid Howells if (ret < 0) 1396cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1397cc53ce53SDavid Howells } 1398cc53ce53SDavid Howells 1399cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1400cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1401cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1402cc53ce53SDavid Howells if (!mounted) 1403cc53ce53SDavid Howells break; 1404cc53ce53SDavid Howells dput(path->dentry); 1405cc53ce53SDavid Howells mntput(path->mnt); 1406cc53ce53SDavid Howells path->mnt = mounted; 1407cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1408cc53ce53SDavid Howells continue; 1409cc53ce53SDavid Howells } 1410cc53ce53SDavid Howells 1411cc53ce53SDavid Howells /* Don't handle automount points here */ 1412cc53ce53SDavid Howells break; 1413cc53ce53SDavid Howells } 1414cc53ce53SDavid Howells return 0; 1415cc53ce53SDavid Howells } 14164d359507SAl Viro EXPORT_SYMBOL(follow_down); 1417cc53ce53SDavid Howells 1418cc53ce53SDavid Howells /* 14199875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14209875cf80SDavid Howells */ 14219875cf80SDavid Howells static void follow_mount(struct path *path) 14229875cf80SDavid Howells { 14239875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14249875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14259875cf80SDavid Howells if (!mounted) 14269875cf80SDavid Howells break; 14279875cf80SDavid Howells dput(path->dentry); 14289875cf80SDavid Howells mntput(path->mnt); 14299875cf80SDavid Howells path->mnt = mounted; 14309875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14319875cf80SDavid Howells } 14329875cf80SDavid Howells } 14339875cf80SDavid Howells 1434eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1435eedf265aSEric W. Biederman { 1436eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1437eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1438eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1439eedf265aSEric W. Biederman dput(old); 1440eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1441eedf265aSEric W. Biederman return -ENOENT; 1442eedf265aSEric W. Biederman return 0; 1443eedf265aSEric W. Biederman } 1444eedf265aSEric W. Biederman 1445397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14461da177e4SLinus Torvalds { 14471da177e4SLinus Torvalds while(1) { 14482a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14492a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14501da177e4SLinus Torvalds break; 14511da177e4SLinus Torvalds } 14524ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1453eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1454eedf265aSEric W. Biederman if (ret) 1455eedf265aSEric W. Biederman return ret; 14561da177e4SLinus Torvalds break; 14571da177e4SLinus Torvalds } 14583088dd70SAl Viro if (!follow_up(&nd->path)) 14591da177e4SLinus Torvalds break; 14601da177e4SLinus Torvalds } 146179ed0226SAl Viro follow_mount(&nd->path); 146231e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1463397d425dSEric W. Biederman return 0; 14641da177e4SLinus Torvalds } 14651da177e4SLinus Torvalds 14661da177e4SLinus Torvalds /* 1467f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1468f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1469baa03890SNick Piggin */ 1470e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1471e3c13928SAl Viro struct dentry *dir, 14726c51e513SAl Viro unsigned int flags) 1473baa03890SNick Piggin { 1474a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1475bad61189SMiklos Szeredi if (dentry) { 1476a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1477bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 147874ff0ffcSAl Viro if (!error) 14795542aa2fSEric W. Biederman d_invalidate(dentry); 1480bad61189SMiklos Szeredi dput(dentry); 148174ff0ffcSAl Viro return ERR_PTR(error); 1482bad61189SMiklos Szeredi } 1483bad61189SMiklos Szeredi } 1484baa03890SNick Piggin return dentry; 1485baa03890SNick Piggin } 1486baa03890SNick Piggin 1487baa03890SNick Piggin /* 148813a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 148913a2c3beSJ. Bruce Fields * unhashed. 1490bad61189SMiklos Szeredi * 1491bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 149244396f4bSJosef Bacik */ 1493bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 149472bd866aSAl Viro unsigned int flags) 149544396f4bSJosef Bacik { 149644396f4bSJosef Bacik struct dentry *old; 149744396f4bSJosef Bacik 149844396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1499bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1500e188dc02SMiklos Szeredi dput(dentry); 150144396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1502e188dc02SMiklos Szeredi } 150344396f4bSJosef Bacik 150472bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 150544396f4bSJosef Bacik if (unlikely(old)) { 150644396f4bSJosef Bacik dput(dentry); 150744396f4bSJosef Bacik dentry = old; 150844396f4bSJosef Bacik } 150944396f4bSJosef Bacik return dentry; 151044396f4bSJosef Bacik } 151144396f4bSJosef Bacik 1512e3c13928SAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 151372bd866aSAl Viro struct dentry *base, unsigned int flags) 1514a3255546SAl Viro { 15156c51e513SAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 1516a3255546SAl Viro 15176c51e513SAl Viro if (dentry) 1518a3255546SAl Viro return dentry; 1519bad61189SMiklos Szeredi 15206c51e513SAl Viro dentry = d_alloc(base, name); 15216c51e513SAl Viro if (unlikely(!dentry)) 15226c51e513SAl Viro return ERR_PTR(-ENOMEM); 15236c51e513SAl Viro 152472bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1525a3255546SAl Viro } 1526a3255546SAl Viro 1527e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1528254cf582SAl Viro struct path *path, struct inode **inode, 1529254cf582SAl Viro unsigned *seqp) 15301da177e4SLinus Torvalds { 15314ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 153231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15335a18fff2SAl Viro int status = 1; 15349875cf80SDavid Howells int err; 15359875cf80SDavid Howells 15363cac260aSAl Viro /* 1537b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15385d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15395d0f49c1SAl Viro * going to fall back to non-racy lookup. 1540b04f784eSNick Piggin */ 154131e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 154231e6b01fSNick Piggin unsigned seq; 1543766c4cbfSAl Viro bool negative; 1544da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15455d0f49c1SAl Viro if (unlikely(!dentry)) { 15464675ac39SAl Viro if (unlazy_walk(nd)) 15475d0f49c1SAl Viro return -ECHILD; 1548e9742b53SAl Viro return 0; 15495d0f49c1SAl Viro } 15505a18fff2SAl Viro 155112f8ad4bSLinus Torvalds /* 155212f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 155312f8ad4bSLinus Torvalds * the dentry name information from lookup. 155412f8ad4bSLinus Torvalds */ 155563afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1556766c4cbfSAl Viro negative = d_is_negative(dentry); 15575d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 155812f8ad4bSLinus Torvalds return -ECHILD; 155912f8ad4bSLinus Torvalds 156012f8ad4bSLinus Torvalds /* 156112f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 156212f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 156312f8ad4bSLinus Torvalds * 156412f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 156512f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 156612f8ad4bSLinus Torvalds */ 15675d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 156831e6b01fSNick Piggin return -ECHILD; 15695a18fff2SAl Viro 1570254cf582SAl Viro *seqp = seq; 15714ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1572209a7fb2SAl Viro if (likely(status > 0)) { 1573daf3761cSTrond Myklebust /* 1574daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1575daf3761cSTrond Myklebust * case that drops it. 1576daf3761cSTrond Myklebust */ 15775d0f49c1SAl Viro if (unlikely(negative)) 1578daf3761cSTrond Myklebust return -ENOENT; 157931e6b01fSNick Piggin path->mnt = mnt; 158031e6b01fSNick Piggin path->dentry = dentry; 1581254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1582e9742b53SAl Viro return 1; 15835d0f49c1SAl Viro } 15844675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1585254cf582SAl Viro return -ECHILD; 1586209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1587209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1588209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15895a18fff2SAl Viro } else { 1590e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 159181e6f520SAl Viro if (unlikely(!dentry)) 1592e9742b53SAl Viro return 0; 15934ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15945d0f49c1SAl Viro } 15955a18fff2SAl Viro if (unlikely(status <= 0)) { 1596e9742b53SAl Viro if (!status) 15975d0f49c1SAl Viro d_invalidate(dentry); 15985a18fff2SAl Viro dput(dentry); 15995a18fff2SAl Viro return status; 16005a18fff2SAl Viro } 1601766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1602766c4cbfSAl Viro dput(dentry); 1603766c4cbfSAl Viro return -ENOENT; 1604766c4cbfSAl Viro } 16055d0f49c1SAl Viro 16061da177e4SLinus Torvalds path->mnt = mnt; 16071da177e4SLinus Torvalds path->dentry = dentry; 1608756daf26SNeilBrown err = follow_managed(path, nd); 1609e9742b53SAl Viro if (likely(err > 0)) 161063afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16118402752eSAl Viro return err; 1612697f514dSMiklos Szeredi } 1613697f514dSMiklos Szeredi 1614697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1615e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1616e3c13928SAl Viro struct dentry *dir, 1617e3c13928SAl Viro unsigned int flags) 1618697f514dSMiklos Szeredi { 161994bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16201936386eSAl Viro struct inode *inode = dir->d_inode; 1621d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16221936386eSAl Viro 16239902af79SAl Viro inode_lock_shared(inode); 16241936386eSAl Viro /* Don't go there if it's already dead */ 162594bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 162694bdd655SAl Viro goto out; 162794bdd655SAl Viro again: 1628d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 162994bdd655SAl Viro if (IS_ERR(dentry)) 163094bdd655SAl Viro goto out; 163194bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1632a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1633949a852eSAl Viro int error = d_revalidate(dentry, flags); 1634949a852eSAl Viro if (unlikely(error <= 0)) { 163594bdd655SAl Viro if (!error) { 1636949a852eSAl Viro d_invalidate(dentry); 1637949a852eSAl Viro dput(dentry); 163894bdd655SAl Viro goto again; 163994bdd655SAl Viro } 164094bdd655SAl Viro dput(dentry); 1641949a852eSAl Viro dentry = ERR_PTR(error); 1642949a852eSAl Viro } 1643949a852eSAl Viro } 164494bdd655SAl Viro } else { 16451936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 164685c7f810SAl Viro d_lookup_done(dentry); 16471936386eSAl Viro if (unlikely(old)) { 16481936386eSAl Viro dput(dentry); 16491936386eSAl Viro dentry = old; 1650949a852eSAl Viro } 1651949a852eSAl Viro } 165294bdd655SAl Viro out: 16539902af79SAl Viro inode_unlock_shared(inode); 1654e3c13928SAl Viro return dentry; 16551da177e4SLinus Torvalds } 16561da177e4SLinus Torvalds 165752094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 165852094c8aSAl Viro { 165952094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16604ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 166152094c8aSAl Viro if (err != -ECHILD) 166252094c8aSAl Viro return err; 16634675ac39SAl Viro if (unlazy_walk(nd)) 166452094c8aSAl Viro return -ECHILD; 166552094c8aSAl Viro } 16664ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 166752094c8aSAl Viro } 166852094c8aSAl Viro 16699856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16709856fa1bSAl Viro { 16719856fa1bSAl Viro if (type == LAST_DOTDOT) { 16729e6697e2SAl Viro if (!nd->root.mnt) 16739e6697e2SAl Viro set_root(nd); 16749856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 167570291aecSAl Viro return follow_dotdot_rcu(nd); 16769856fa1bSAl Viro } else 1677397d425dSEric W. Biederman return follow_dotdot(nd); 16789856fa1bSAl Viro } 16799856fa1bSAl Viro return 0; 16809856fa1bSAl Viro } 16819856fa1bSAl Viro 1682181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1683181548c0SAl Viro struct inode *inode, unsigned seq) 1684d63ff28fSAl Viro { 1685626de996SAl Viro int error; 16861cf2665bSAl Viro struct saved *last; 1687756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1688626de996SAl Viro path_to_nameidata(link, nd); 1689626de996SAl Viro return -ELOOP; 1690626de996SAl Viro } 1691bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1692cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1693cd179f44SAl Viro mntget(link->mnt); 16947973387aSAl Viro } 1695626de996SAl Viro error = nd_alloc_stack(nd); 1696626de996SAl Viro if (unlikely(error)) { 1697bc40aee0SAl Viro if (error == -ECHILD) { 1698ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1699ad1633a1SAl Viro drop_links(nd); 1700ad1633a1SAl Viro nd->depth = 0; 1701ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1702ad1633a1SAl Viro nd->path.mnt = NULL; 1703ad1633a1SAl Viro nd->path.dentry = NULL; 1704ad1633a1SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1705ad1633a1SAl Viro nd->root.mnt = NULL; 1706ad1633a1SAl Viro rcu_read_unlock(); 17074675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1708bc40aee0SAl Viro error = nd_alloc_stack(nd); 1709bc40aee0SAl Viro } 1710bc40aee0SAl Viro if (error) { 1711cd179f44SAl Viro path_put(link); 1712626de996SAl Viro return error; 1713626de996SAl Viro } 1714bc40aee0SAl Viro } 1715626de996SAl Viro 1716ab104923SAl Viro last = nd->stack + nd->depth++; 17171cf2665bSAl Viro last->link = *link; 1718fceef393SAl Viro clear_delayed_call(&last->done); 1719fceef393SAl Viro nd->link_inode = inode; 17200450b2d1SAl Viro last->seq = seq; 1721d63ff28fSAl Viro return 1; 1722d63ff28fSAl Viro } 1723d63ff28fSAl Viro 17248f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 172531d66bcdSAl Viro 17263ddcd056SLinus Torvalds /* 17273ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17283ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17293ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17303ddcd056SLinus Torvalds * for the common case. 17313ddcd056SLinus Torvalds */ 17328f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17338f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17343ddcd056SLinus Torvalds { 173531d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 173631d66bcdSAl Viro put_link(nd); 17378f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17388f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17398f64fb1cSAl Viro /* not a symlink or should not follow */ 17408f64fb1cSAl Viro path_to_nameidata(path, nd); 17418f64fb1cSAl Viro nd->inode = inode; 17428f64fb1cSAl Viro nd->seq = seq; 1743d63ff28fSAl Viro return 0; 17448f64fb1cSAl Viro } 1745a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1746a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17478f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1748a7f77542SAl Viro return -ECHILD; 1749a7f77542SAl Viro } 17508f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17513ddcd056SLinus Torvalds } 17523ddcd056SLinus Torvalds 17534693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1754ce57dfc1SAl Viro { 1755caa85634SAl Viro struct path path; 1756ce57dfc1SAl Viro struct inode *inode; 1757254cf582SAl Viro unsigned seq; 1758ce57dfc1SAl Viro int err; 1759ce57dfc1SAl Viro /* 1760ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1761ce57dfc1SAl Viro * to be able to know about the current root directory and 1762ce57dfc1SAl Viro * parent relationships. 1763ce57dfc1SAl Viro */ 17644693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17654693a547SAl Viro err = handle_dots(nd, nd->last_type); 17661c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17674693a547SAl Viro put_link(nd); 17684693a547SAl Viro return err; 17694693a547SAl Viro } 1770254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1771e9742b53SAl Viro if (unlikely(err <= 0)) { 1772697f514dSMiklos Szeredi if (err < 0) 1773f0a9ba70SAl Viro return err; 1774e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1775e3c13928SAl Viro nd->flags); 1776e3c13928SAl Viro if (IS_ERR(path.dentry)) 1777e3c13928SAl Viro return PTR_ERR(path.dentry); 17787500c38aSAl Viro 1779e3c13928SAl Viro path.mnt = nd->path.mnt; 1780e3c13928SAl Viro err = follow_managed(&path, nd); 1781e3c13928SAl Viro if (unlikely(err < 0)) 1782f0a9ba70SAl Viro return err; 1783697f514dSMiklos Szeredi 17847500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17857500c38aSAl Viro path_to_nameidata(&path, nd); 17867500c38aSAl Viro return -ENOENT; 17877500c38aSAl Viro } 17887500c38aSAl Viro 1789254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1790d4565649SAl Viro inode = d_backing_inode(path.dentry); 1791766c4cbfSAl Viro } 1792697f514dSMiklos Szeredi 17938f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1794ce57dfc1SAl Viro } 1795ce57dfc1SAl Viro 17961da177e4SLinus Torvalds /* 1797bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1798bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1799bfcfaa77SLinus Torvalds * 1800bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1801bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1802bfcfaa77SLinus Torvalds * fast. 1803bfcfaa77SLinus Torvalds * 1804bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1805bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1806bfcfaa77SLinus Torvalds * crossing operation. 1807bfcfaa77SLinus Torvalds * 1808bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1809bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1810bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1811bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1812bfcfaa77SLinus Torvalds */ 1813bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1814bfcfaa77SLinus Torvalds 1815f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1816bfcfaa77SLinus Torvalds 1817468a9428SGeorge Spelvin #ifdef HASH_MIX 1818bfcfaa77SLinus Torvalds 1819468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1820468a9428SGeorge Spelvin 1821468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18222a18da7aSGeorge Spelvin /* 18232a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18242a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18252a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18262a18da7aSGeorge Spelvin * and no temporaries. 18272a18da7aSGeorge Spelvin * 18282a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18292a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18302a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18312a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18322a18da7aSGeorge Spelvin * 18332a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18342a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18352a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18362a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18372a18da7aSGeorge Spelvin * 18382a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18392a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18402a18da7aSGeorge Spelvin * toggling any given output bit. 18412a18da7aSGeorge Spelvin * 18422a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18432a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18442a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18452a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18462a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18472a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18482a18da7aSGeorge Spelvin * Perfect: 8192 258048 18492a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18502a18da7aSGeorge Spelvin */ 18512a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18522a18da7aSGeorge Spelvin ( x ^= (a), \ 18532a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18542a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18552a18da7aSGeorge Spelvin y *= 9 ) 1856bfcfaa77SLinus Torvalds 18570fed3ac8SGeorge Spelvin /* 18582a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18592a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18602a18da7aSGeorge Spelvin * work done before the hash value is used. 18610fed3ac8SGeorge Spelvin */ 18622a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18630fed3ac8SGeorge Spelvin { 18642a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18652a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18662a18da7aSGeorge Spelvin return y >> 32; 18670fed3ac8SGeorge Spelvin } 18680fed3ac8SGeorge Spelvin 1869bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1870bfcfaa77SLinus Torvalds 18712a18da7aSGeorge Spelvin /* 18722a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18732a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18742a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18752a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18762a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18772a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18782a18da7aSGeorge Spelvin * Perfect: 2048 31744 18792a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18802a18da7aSGeorge Spelvin */ 18812a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18822a18da7aSGeorge Spelvin ( x ^= (a), \ 18832a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18842a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18852a18da7aSGeorge Spelvin y *= 9 ) 1886bfcfaa77SLinus Torvalds 18872a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18880fed3ac8SGeorge Spelvin { 18892a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18902a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18910fed3ac8SGeorge Spelvin } 18920fed3ac8SGeorge Spelvin 1893bfcfaa77SLinus Torvalds #endif 1894bfcfaa77SLinus Torvalds 18952a18da7aSGeorge Spelvin /* 18962a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18972a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18982a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18992a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19002a18da7aSGeorge Spelvin * finds the delimiter after the name. 19012a18da7aSGeorge Spelvin */ 19028387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1903bfcfaa77SLinus Torvalds { 19048387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1905bfcfaa77SLinus Torvalds 1906bfcfaa77SLinus Torvalds for (;;) { 1907fcfd2fbfSGeorge Spelvin if (!len) 1908fcfd2fbfSGeorge Spelvin goto done; 1909e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1910bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1911bfcfaa77SLinus Torvalds break; 19122a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1913bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1914bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1915bfcfaa77SLinus Torvalds } 19162a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1917bfcfaa77SLinus Torvalds done: 19182a18da7aSGeorge Spelvin return fold_hash(x, y); 1919bfcfaa77SLinus Torvalds } 1920bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1921bfcfaa77SLinus Torvalds 1922fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19238387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1924fcfd2fbfSGeorge Spelvin { 19258387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19268387ff25SLinus Torvalds unsigned long adata, mask, len; 1927fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1928fcfd2fbfSGeorge Spelvin 19298387ff25SLinus Torvalds len = 0; 19308387ff25SLinus Torvalds goto inside; 19318387ff25SLinus Torvalds 1932fcfd2fbfSGeorge Spelvin do { 19332a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1934fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19358387ff25SLinus Torvalds inside: 1936fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1937fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1938fcfd2fbfSGeorge Spelvin 1939fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1940fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19412a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1942fcfd2fbfSGeorge Spelvin 19432a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1944fcfd2fbfSGeorge Spelvin } 1945fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1946fcfd2fbfSGeorge Spelvin 1947bfcfaa77SLinus Torvalds /* 1948bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1949d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1950bfcfaa77SLinus Torvalds */ 19518387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1952bfcfaa77SLinus Torvalds { 19538387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19548387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 195536126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1956bfcfaa77SLinus Torvalds 19578387ff25SLinus Torvalds len = 0; 19588387ff25SLinus Torvalds goto inside; 19598387ff25SLinus Torvalds 1960bfcfaa77SLinus Torvalds do { 19612a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1962bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19638387ff25SLinus Torvalds inside: 1964e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 196536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 196636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1967bfcfaa77SLinus Torvalds 196836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 196936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 197036126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19712a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 197236126f8fSLinus Torvalds 19732a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1974bfcfaa77SLinus Torvalds } 1975bfcfaa77SLinus Torvalds 19762a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1977bfcfaa77SLinus Torvalds 1978fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19798387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19800145acc2SLinus Torvalds { 19818387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 19820145acc2SLinus Torvalds while (len--) 1983fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19840145acc2SLinus Torvalds return end_name_hash(hash); 19850145acc2SLinus Torvalds } 1986ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19870145acc2SLinus Torvalds 1988fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19898387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1990fcfd2fbfSGeorge Spelvin { 19918387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1992fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1993fcfd2fbfSGeorge Spelvin 1994fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1995e0ab7af9SGeorge Spelvin while (c) { 1996fcfd2fbfSGeorge Spelvin len++; 1997fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1998fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1999e0ab7af9SGeorge Spelvin } 2000fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2001fcfd2fbfSGeorge Spelvin } 2002f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2003fcfd2fbfSGeorge Spelvin 20043ddcd056SLinus Torvalds /* 2005200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2006200e9ef7SLinus Torvalds * one character. 2007200e9ef7SLinus Torvalds */ 20088387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2009200e9ef7SLinus Torvalds { 20108387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2011200e9ef7SLinus Torvalds unsigned long len = 0, c; 2012200e9ef7SLinus Torvalds 2013200e9ef7SLinus Torvalds c = (unsigned char)*name; 2014200e9ef7SLinus Torvalds do { 2015200e9ef7SLinus Torvalds len++; 2016200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2017200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2018200e9ef7SLinus Torvalds } while (c && c != '/'); 2019d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2020200e9ef7SLinus Torvalds } 2021200e9ef7SLinus Torvalds 2022bfcfaa77SLinus Torvalds #endif 2023bfcfaa77SLinus Torvalds 2024200e9ef7SLinus Torvalds /* 20251da177e4SLinus Torvalds * Name resolution. 2026ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2027ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20281da177e4SLinus Torvalds * 2029ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2030ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20311da177e4SLinus Torvalds */ 20326de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20331da177e4SLinus Torvalds { 20341da177e4SLinus Torvalds int err; 20351da177e4SLinus Torvalds 20361da177e4SLinus Torvalds while (*name=='/') 20371da177e4SLinus Torvalds name++; 20381da177e4SLinus Torvalds if (!*name) 20399e18f10aSAl Viro return 0; 20401da177e4SLinus Torvalds 20411da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20421da177e4SLinus Torvalds for(;;) { 2043d6bb3e90SLinus Torvalds u64 hash_len; 2044fe479a58SAl Viro int type; 20451da177e4SLinus Torvalds 204652094c8aSAl Viro err = may_lookup(nd); 20471da177e4SLinus Torvalds if (err) 20483595e234SAl Viro return err; 20491da177e4SLinus Torvalds 20508387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20511da177e4SLinus Torvalds 2052fe479a58SAl Viro type = LAST_NORM; 2053d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2054fe479a58SAl Viro case 2: 2055200e9ef7SLinus Torvalds if (name[1] == '.') { 2056fe479a58SAl Viro type = LAST_DOTDOT; 205716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 205816c2cd71SAl Viro } 2059fe479a58SAl Viro break; 2060fe479a58SAl Viro case 1: 2061fe479a58SAl Viro type = LAST_DOT; 2062fe479a58SAl Viro } 20635a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20645a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 206516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20665a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2067a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2068da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20695a202bcdSAl Viro if (err < 0) 20703595e234SAl Viro return err; 2071d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2072d6bb3e90SLinus Torvalds name = this.name; 20735a202bcdSAl Viro } 20745a202bcdSAl Viro } 2075fe479a58SAl Viro 2076d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2077d6bb3e90SLinus Torvalds nd->last.name = name; 20785f4a6a69SAl Viro nd->last_type = type; 20795f4a6a69SAl Viro 2080d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2081d6bb3e90SLinus Torvalds if (!*name) 2082bdf6cbf1SAl Viro goto OK; 2083200e9ef7SLinus Torvalds /* 2084200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2085200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2086200e9ef7SLinus Torvalds */ 2087200e9ef7SLinus Torvalds do { 2088d6bb3e90SLinus Torvalds name++; 2089d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20908620c238SAl Viro if (unlikely(!*name)) { 20918620c238SAl Viro OK: 2092368ee9baSAl Viro /* pathname body, done */ 20938620c238SAl Viro if (!nd->depth) 20948620c238SAl Viro return 0; 20958620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2096368ee9baSAl Viro /* trailing symlink, done */ 20978620c238SAl Viro if (!name) 20988620c238SAl Viro return 0; 20998620c238SAl Viro /* last component of nested symlink */ 21008f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 21011c4ff1a8SAl Viro } else { 21021c4ff1a8SAl Viro /* not the last component */ 21038f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 21048620c238SAl Viro } 2105ce57dfc1SAl Viro if (err < 0) 21063595e234SAl Viro return err; 2107fe479a58SAl Viro 2108ce57dfc1SAl Viro if (err) { 2109626de996SAl Viro const char *s = get_link(nd); 21105a460275SAl Viro 2111a1c83681SViresh Kumar if (IS_ERR(s)) 21123595e234SAl Viro return PTR_ERR(s); 2113172a39a0SAl Viro err = 0; 211412b09578SAl Viro if (unlikely(!s)) { 211512b09578SAl Viro /* jumped */ 2116b9ff4429SAl Viro put_link(nd); 211712b09578SAl Viro } else { 2118071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 211932cd7468SAl Viro name = s; 21209e18f10aSAl Viro continue; 212148c8b0c5SAl Viro } 212231e6b01fSNick Piggin } 212397242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 212497242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21254675ac39SAl Viro if (unlazy_walk(nd)) 212697242f99SAl Viro return -ECHILD; 212797242f99SAl Viro } 21283595e234SAl Viro return -ENOTDIR; 21295f4a6a69SAl Viro } 2130ce57dfc1SAl Viro } 213197242f99SAl Viro } 21321da177e4SLinus Torvalds 2133c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 213431e6b01fSNick Piggin { 2135c8a53ee5SAl Viro const char *s = nd->name->name; 213631e6b01fSNick Piggin 2137c0eb027eSLinus Torvalds if (!*s) 2138c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2139c0eb027eSLinus Torvalds 214031e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2141980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 214231e6b01fSNick Piggin nd->depth = 0; 21435b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2144b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2145b18825a7SDavid Howells struct inode *inode = root->d_inode; 214693893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2147368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21485b6ca027SAl Viro nd->path = nd->root; 21495b6ca027SAl Viro nd->inode = inode; 21505b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21518b61e74fSAl Viro rcu_read_lock(); 21525b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21538f47a016SAl Viro nd->root_seq = nd->seq; 215448a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21555b6ca027SAl Viro } else { 21565b6ca027SAl Viro path_get(&nd->path); 21575b6ca027SAl Viro } 2158368ee9baSAl Viro return s; 21595b6ca027SAl Viro } 21605b6ca027SAl Viro 216131e6b01fSNick Piggin nd->root.mnt = NULL; 2162248fb5b9SAl Viro nd->path.mnt = NULL; 2163248fb5b9SAl Viro nd->path.dentry = NULL; 216431e6b01fSNick Piggin 216548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2166fd2f7cb5SAl Viro if (*s == '/') { 21679e6697e2SAl Viro if (flags & LOOKUP_RCU) 21688b61e74fSAl Viro rcu_read_lock(); 2169e41f7d4eSAl Viro set_root(nd); 2170248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2171ef55d917SAl Viro return s; 2172ef55d917SAl Viro nd->root.mnt = NULL; 2173ef55d917SAl Viro rcu_read_unlock(); 2174ef55d917SAl Viro return ERR_PTR(-ECHILD); 2175c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2176e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 217731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2178c28cc364SNick Piggin unsigned seq; 217931e6b01fSNick Piggin 21808b61e74fSAl Viro rcu_read_lock(); 218131e6b01fSNick Piggin 2182c28cc364SNick Piggin do { 2183c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 218431e6b01fSNick Piggin nd->path = fs->pwd; 2185ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2186c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2187c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2188e41f7d4eSAl Viro } else { 2189e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2190ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2191e41f7d4eSAl Viro } 2192ef55d917SAl Viro return s; 219331e6b01fSNick Piggin } else { 2194582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2195c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 219631e6b01fSNick Piggin struct dentry *dentry; 219731e6b01fSNick Piggin 21982903ff01SAl Viro if (!f.file) 2199368ee9baSAl Viro return ERR_PTR(-EBADF); 220031e6b01fSNick Piggin 22012903ff01SAl Viro dentry = f.file->f_path.dentry; 220231e6b01fSNick Piggin 2203fd2f7cb5SAl Viro if (*s) { 220444b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 22052903ff01SAl Viro fdput(f); 2206368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2207f52e0c11SAl Viro } 22082903ff01SAl Viro } 22092903ff01SAl Viro 22102903ff01SAl Viro nd->path = f.file->f_path; 2211e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22128b61e74fSAl Viro rcu_read_lock(); 221334a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 221434a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22155590ff0dSUlrich Drepper } else { 22162903ff01SAl Viro path_get(&nd->path); 221734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22181da177e4SLinus Torvalds } 221934a26b99SAl Viro fdput(f); 2220368ee9baSAl Viro return s; 2221e41f7d4eSAl Viro } 22229b4a9b14SAl Viro } 22239b4a9b14SAl Viro 22243bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 222595fa25d9SAl Viro { 222695fa25d9SAl Viro const char *s; 2227fec2fa24SAl Viro int error = may_follow_link(nd); 2228deb106c6SAl Viro if (unlikely(error)) 22293bdba28bSAl Viro return ERR_PTR(error); 223095fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2231fab51e8aSAl Viro nd->stack[0].name = NULL; 22323b2e7f75SAl Viro s = get_link(nd); 2233deb106c6SAl Viro return s ? s : ""; 223495fa25d9SAl Viro } 223595fa25d9SAl Viro 2236caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2237bd92d7feSAl Viro { 2238bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2239bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2240bd92d7feSAl Viro 2241bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22421c4ff1a8SAl Viro return walk_component(nd, 0); 2243bd92d7feSAl Viro } 2244bd92d7feSAl Viro 22454f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22464f757f3cSAl Viro { 22474f757f3cSAl Viro struct path path = nd->path; 22484f757f3cSAl Viro struct inode *inode = nd->inode; 22494f757f3cSAl Viro unsigned seq = nd->seq; 22504f757f3cSAl Viro int err; 22514f757f3cSAl Viro 22524f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22534f757f3cSAl Viro /* 22544f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22554f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22564f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22574f757f3cSAl Viro */ 22584f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22594f757f3cSAl Viro return -ECHILD; 22604f757f3cSAl Viro } else { 22614f757f3cSAl Viro dget(path.dentry); 22624f757f3cSAl Viro err = follow_managed(&path, nd); 22634f757f3cSAl Viro if (unlikely(err < 0)) 22644f757f3cSAl Viro return err; 22654f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22664f757f3cSAl Viro seq = 0; 22674f757f3cSAl Viro } 22684f757f3cSAl Viro path_to_nameidata(&path, nd); 22694f757f3cSAl Viro nd->inode = inode; 22704f757f3cSAl Viro nd->seq = seq; 22714f757f3cSAl Viro return 0; 22724f757f3cSAl Viro } 22734f757f3cSAl Viro 22749b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2275c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22769b4a9b14SAl Viro { 2277c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2278bd92d7feSAl Viro int err; 227931e6b01fSNick Piggin 2280368ee9baSAl Viro if (IS_ERR(s)) 2281368ee9baSAl Viro return PTR_ERR(s); 22824f757f3cSAl Viro 22834f757f3cSAl Viro if (unlikely(flags & LOOKUP_DOWN)) { 22844f757f3cSAl Viro err = handle_lookup_down(nd); 22854f757f3cSAl Viro if (unlikely(err < 0)) { 22864f757f3cSAl Viro terminate_walk(nd); 22874f757f3cSAl Viro return err; 22884f757f3cSAl Viro } 22894f757f3cSAl Viro } 22904f757f3cSAl Viro 22913bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22923bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22933bdba28bSAl Viro s = trailing_symlink(nd); 22943bdba28bSAl Viro if (IS_ERR(s)) { 22953bdba28bSAl Viro err = PTR_ERR(s); 22966d7b5aaeSAl Viro break; 2297bd92d7feSAl Viro } 2298bd92d7feSAl Viro } 22999f1fafeeSAl Viro if (!err) 23009f1fafeeSAl Viro err = complete_walk(nd); 2301bd92d7feSAl Viro 2302deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2303deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2304bd23a539SAl Viro err = -ENOTDIR; 2305625b6d10SAl Viro if (!err) { 2306625b6d10SAl Viro *path = nd->path; 2307625b6d10SAl Viro nd->path.mnt = NULL; 2308625b6d10SAl Viro nd->path.dentry = NULL; 2309625b6d10SAl Viro } 2310deb106c6SAl Viro terminate_walk(nd); 2311bd92d7feSAl Viro return err; 231231e6b01fSNick Piggin } 231331e6b01fSNick Piggin 2314625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 23159ad1aaa6SAl Viro struct path *path, struct path *root) 2316873f1eedSJeff Layton { 2317894bc8c4SAl Viro int retval; 23189883d185SAl Viro struct nameidata nd; 2319abc9f5beSAl Viro if (IS_ERR(name)) 2320abc9f5beSAl Viro return PTR_ERR(name); 23219ad1aaa6SAl Viro if (unlikely(root)) { 23229ad1aaa6SAl Viro nd.root = *root; 23239ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23249ad1aaa6SAl Viro } 23259883d185SAl Viro set_nameidata(&nd, dfd, name); 2326c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2327873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2328c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2329873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2330c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2331873f1eedSJeff Layton 2332873f1eedSJeff Layton if (likely(!retval)) 2333625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 23349883d185SAl Viro restore_nameidata(); 2335e4bd1c1aSAl Viro putname(name); 2336873f1eedSJeff Layton return retval; 2337873f1eedSJeff Layton } 2338873f1eedSJeff Layton 23398bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2340c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2341391172c4SAl Viro struct path *parent) 23428bcb77faSAl Viro { 2343c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2344368ee9baSAl Viro int err; 2345368ee9baSAl Viro if (IS_ERR(s)) 2346368ee9baSAl Viro return PTR_ERR(s); 2347368ee9baSAl Viro err = link_path_walk(s, nd); 23488bcb77faSAl Viro if (!err) 23498bcb77faSAl Viro err = complete_walk(nd); 2350391172c4SAl Viro if (!err) { 2351391172c4SAl Viro *parent = nd->path; 2352391172c4SAl Viro nd->path.mnt = NULL; 2353391172c4SAl Viro nd->path.dentry = NULL; 2354391172c4SAl Viro } 2355deb106c6SAl Viro terminate_walk(nd); 23568bcb77faSAl Viro return err; 23578bcb77faSAl Viro } 23588bcb77faSAl Viro 23595c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2360391172c4SAl Viro unsigned int flags, struct path *parent, 2361391172c4SAl Viro struct qstr *last, int *type) 23628bcb77faSAl Viro { 23638bcb77faSAl Viro int retval; 23649883d185SAl Viro struct nameidata nd; 23658bcb77faSAl Viro 23665c31b6ceSAl Viro if (IS_ERR(name)) 23675c31b6ceSAl Viro return name; 23689883d185SAl Viro set_nameidata(&nd, dfd, name); 2369c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23708bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2371c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23728bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2373c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2374391172c4SAl Viro if (likely(!retval)) { 2375391172c4SAl Viro *last = nd.last; 2376391172c4SAl Viro *type = nd.last_type; 2377391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23785c31b6ceSAl Viro } else { 23795c31b6ceSAl Viro putname(name); 23805c31b6ceSAl Viro name = ERR_PTR(retval); 2381391172c4SAl Viro } 23829883d185SAl Viro restore_nameidata(); 23835c31b6ceSAl Viro return name; 23848bcb77faSAl Viro } 23858bcb77faSAl Viro 238679714f72SAl Viro /* does lookup, returns the object with parent locked */ 238779714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23885590ff0dSUlrich Drepper { 23895c31b6ceSAl Viro struct filename *filename; 23905c31b6ceSAl Viro struct dentry *d; 2391391172c4SAl Viro struct qstr last; 2392391172c4SAl Viro int type; 239351689104SPaul Moore 23945c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23955c31b6ceSAl Viro &last, &type); 239651689104SPaul Moore if (IS_ERR(filename)) 239751689104SPaul Moore return ERR_CAST(filename); 23985c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2399391172c4SAl Viro path_put(path); 24005c31b6ceSAl Viro putname(filename); 24015c31b6ceSAl Viro return ERR_PTR(-EINVAL); 240279714f72SAl Viro } 24035955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2404391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 240579714f72SAl Viro if (IS_ERR(d)) { 24065955102cSAl Viro inode_unlock(path->dentry->d_inode); 2407391172c4SAl Viro path_put(path); 240879714f72SAl Viro } 240951689104SPaul Moore putname(filename); 241079714f72SAl Viro return d; 24115590ff0dSUlrich Drepper } 24125590ff0dSUlrich Drepper 2413d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2414d1811465SAl Viro { 2415abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2416abc9f5beSAl Viro flags, path, NULL); 2417d1811465SAl Viro } 24184d359507SAl Viro EXPORT_SYMBOL(kern_path); 2419d1811465SAl Viro 242016f18200SJosef 'Jeff' Sipek /** 242116f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 242216f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 242316f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 242416f18200SJosef 'Jeff' Sipek * @name: pointer to file name 242516f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2426e0a01249SAl Viro * @path: pointer to struct path to fill 242716f18200SJosef 'Jeff' Sipek */ 242816f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 242916f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2430e0a01249SAl Viro struct path *path) 243116f18200SJosef 'Jeff' Sipek { 24329ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24339ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2434abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2435abc9f5beSAl Viro flags , path, &root); 243616f18200SJosef 'Jeff' Sipek } 24374d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 243816f18200SJosef 'Jeff' Sipek 2439eead1911SChristoph Hellwig /** 2440a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2441eead1911SChristoph Hellwig * @name: pathname component to lookup 2442eead1911SChristoph Hellwig * @base: base directory to lookup from 2443eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2444eead1911SChristoph Hellwig * 2445a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24469e7543e9SAl Viro * not be called by generic code. 2447bbddca8eSNeilBrown * 2448bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2449eead1911SChristoph Hellwig */ 2450057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2451057f6c01SJames Morris { 2452057f6c01SJames Morris struct qstr this; 24536a96ba54SAl Viro unsigned int c; 2454cda309deSMiklos Szeredi int err; 2455057f6c01SJames Morris 24565955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24572f9092e1SDavid Woodhouse 24586a96ba54SAl Viro this.name = name; 24596a96ba54SAl Viro this.len = len; 24608387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 24616a96ba54SAl Viro if (!len) 24626a96ba54SAl Viro return ERR_PTR(-EACCES); 24636a96ba54SAl Viro 246421d8a15aSAl Viro if (unlikely(name[0] == '.')) { 246521d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 246621d8a15aSAl Viro return ERR_PTR(-EACCES); 246721d8a15aSAl Viro } 246821d8a15aSAl Viro 24696a96ba54SAl Viro while (len--) { 24706a96ba54SAl Viro c = *(const unsigned char *)name++; 24716a96ba54SAl Viro if (c == '/' || c == '\0') 24726a96ba54SAl Viro return ERR_PTR(-EACCES); 24736a96ba54SAl Viro } 24745a202bcdSAl Viro /* 24755a202bcdSAl Viro * See if the low-level filesystem might want 24765a202bcdSAl Viro * to use its own hash.. 24775a202bcdSAl Viro */ 24785a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2479da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24805a202bcdSAl Viro if (err < 0) 24815a202bcdSAl Viro return ERR_PTR(err); 24825a202bcdSAl Viro } 2483eead1911SChristoph Hellwig 2484cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2485cda309deSMiklos Szeredi if (err) 2486cda309deSMiklos Szeredi return ERR_PTR(err); 2487cda309deSMiklos Szeredi 248872bd866aSAl Viro return __lookup_hash(&this, base, 0); 2489057f6c01SJames Morris } 24904d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2491057f6c01SJames Morris 2492bbddca8eSNeilBrown /** 2493bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2494bbddca8eSNeilBrown * @name: pathname component to lookup 2495bbddca8eSNeilBrown * @base: base directory to lookup from 2496bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2497bbddca8eSNeilBrown * 2498bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2499bbddca8eSNeilBrown * not be called by generic code. 2500bbddca8eSNeilBrown * 2501bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2502bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2503bbddca8eSNeilBrown */ 2504bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2505bbddca8eSNeilBrown struct dentry *base, int len) 2506bbddca8eSNeilBrown { 2507bbddca8eSNeilBrown struct qstr this; 2508bbddca8eSNeilBrown unsigned int c; 2509bbddca8eSNeilBrown int err; 251020d00ee8SLinus Torvalds struct dentry *ret; 2511bbddca8eSNeilBrown 2512bbddca8eSNeilBrown this.name = name; 2513bbddca8eSNeilBrown this.len = len; 25148387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 2515bbddca8eSNeilBrown if (!len) 2516bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2517bbddca8eSNeilBrown 2518bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2519bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2520bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2521bbddca8eSNeilBrown } 2522bbddca8eSNeilBrown 2523bbddca8eSNeilBrown while (len--) { 2524bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2525bbddca8eSNeilBrown if (c == '/' || c == '\0') 2526bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2527bbddca8eSNeilBrown } 2528bbddca8eSNeilBrown /* 2529bbddca8eSNeilBrown * See if the low-level filesystem might want 2530bbddca8eSNeilBrown * to use its own hash.. 2531bbddca8eSNeilBrown */ 2532bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2533bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2534bbddca8eSNeilBrown if (err < 0) 2535bbddca8eSNeilBrown return ERR_PTR(err); 2536bbddca8eSNeilBrown } 2537bbddca8eSNeilBrown 2538bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2539bbddca8eSNeilBrown if (err) 2540bbddca8eSNeilBrown return ERR_PTR(err); 2541bbddca8eSNeilBrown 254220d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 254320d00ee8SLinus Torvalds if (!ret) 254420d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 254520d00ee8SLinus Torvalds return ret; 2546bbddca8eSNeilBrown } 2547bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2548bbddca8eSNeilBrown 2549eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2550eedf265aSEric W. Biederman int path_pts(struct path *path) 2551eedf265aSEric W. Biederman { 2552eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2553eedf265aSEric W. Biederman * the input path. 2554eedf265aSEric W. Biederman */ 2555eedf265aSEric W. Biederman struct dentry *child, *parent; 2556eedf265aSEric W. Biederman struct qstr this; 2557eedf265aSEric W. Biederman int ret; 2558eedf265aSEric W. Biederman 2559eedf265aSEric W. Biederman ret = path_parent_directory(path); 2560eedf265aSEric W. Biederman if (ret) 2561eedf265aSEric W. Biederman return ret; 2562eedf265aSEric W. Biederman 2563eedf265aSEric W. Biederman parent = path->dentry; 2564eedf265aSEric W. Biederman this.name = "pts"; 2565eedf265aSEric W. Biederman this.len = 3; 2566eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2567eedf265aSEric W. Biederman if (!child) 2568eedf265aSEric W. Biederman return -ENOENT; 2569eedf265aSEric W. Biederman 2570eedf265aSEric W. Biederman path->dentry = child; 2571eedf265aSEric W. Biederman dput(parent); 2572eedf265aSEric W. Biederman follow_mount(path); 2573eedf265aSEric W. Biederman return 0; 2574eedf265aSEric W. Biederman } 2575eedf265aSEric W. Biederman #endif 2576eedf265aSEric W. Biederman 25771fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25781fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25791da177e4SLinus Torvalds { 2580abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2581abc9f5beSAl Viro flags, path, NULL); 25821da177e4SLinus Torvalds } 2583b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25841fa1e7f6SAndy Whitcroft 25858033426eSJeff Layton /** 2586197df04cSAl Viro * mountpoint_last - look up last component for umount 25878033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25888033426eSJeff Layton * 25898033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25908033426eSJeff Layton * need to resolve the path without doing any revalidation. 25918033426eSJeff Layton * 25928033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25938033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25948033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25958033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25968033426eSJeff Layton * bogus and it doesn't exist. 25978033426eSJeff Layton * 25988033426eSJeff Layton * Returns: 25998033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2600ba8f4613SAl Viro * lookup found a negative dentry. 26018033426eSJeff Layton * 2602ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2603ba8f4613SAl Viro * symlink that needs to be followed. 26048033426eSJeff Layton * 26058033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2606ba8f4613SAl Viro * that needs to be followed. 26078033426eSJeff Layton */ 26088033426eSJeff Layton static int 2609ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 26108033426eSJeff Layton { 26118033426eSJeff Layton int error = 0; 26128033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2613ba8f4613SAl Viro struct path path; 26148033426eSJeff Layton 261535759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 261635759521SAl Viro if (nd->flags & LOOKUP_RCU) { 26174675ac39SAl Viro if (unlazy_walk(nd)) 2618deb106c6SAl Viro return -ECHILD; 26198033426eSJeff Layton } 26208033426eSJeff Layton 26218033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26228033426eSJeff Layton 26238033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26248033426eSJeff Layton error = handle_dots(nd, nd->last_type); 262535759521SAl Viro if (error) 2626deb106c6SAl Viro return error; 2627ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2628949a852eSAl Viro } else { 2629ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2630ba8f4613SAl Viro if (!path.dentry) { 26318033426eSJeff Layton /* 2632949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2633949a852eSAl Viro * cache, so that means that this dentry is probably 2634949a852eSAl Viro * a symlink or the path doesn't actually point 2635949a852eSAl Viro * to a mounted dentry. 26368033426eSJeff Layton */ 2637ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2638949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2639ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2640ba8f4613SAl Viro return PTR_ERR(path.dentry); 26418033426eSJeff Layton } 2642bcceeebaSDave Jones } 2643ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2644ba8f4613SAl Viro dput(path.dentry); 2645deb106c6SAl Viro return -ENOENT; 264635759521SAl Viro } 2647ba8f4613SAl Viro path.mnt = nd->path.mnt; 26488f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26498033426eSJeff Layton } 26508033426eSJeff Layton 26518033426eSJeff Layton /** 2652197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26532a78b857SMasanari Iida * @nd: lookup context 26548033426eSJeff Layton * @flags: lookup flags 2655c8a53ee5SAl Viro * @path: pointer to container for result 26568033426eSJeff Layton * 26578033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2658606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26598033426eSJeff Layton */ 26608033426eSJeff Layton static int 2661c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26628033426eSJeff Layton { 2663c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2664368ee9baSAl Viro int err; 2665368ee9baSAl Viro if (IS_ERR(s)) 2666368ee9baSAl Viro return PTR_ERR(s); 26673bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2668ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26693bdba28bSAl Viro s = trailing_symlink(nd); 26703bdba28bSAl Viro if (IS_ERR(s)) { 26713bdba28bSAl Viro err = PTR_ERR(s); 26728033426eSJeff Layton break; 26738033426eSJeff Layton } 26743bdba28bSAl Viro } 2675ba8f4613SAl Viro if (!err) { 2676ba8f4613SAl Viro *path = nd->path; 2677ba8f4613SAl Viro nd->path.mnt = NULL; 2678ba8f4613SAl Viro nd->path.dentry = NULL; 2679ba8f4613SAl Viro follow_mount(path); 2680ba8f4613SAl Viro } 2681deb106c6SAl Viro terminate_walk(nd); 26828033426eSJeff Layton return err; 26838033426eSJeff Layton } 26848033426eSJeff Layton 26852d864651SAl Viro static int 2686668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26872d864651SAl Viro unsigned int flags) 26882d864651SAl Viro { 26899883d185SAl Viro struct nameidata nd; 2690cbaab2dbSAl Viro int error; 2691668696dcSAl Viro if (IS_ERR(name)) 2692668696dcSAl Viro return PTR_ERR(name); 26939883d185SAl Viro set_nameidata(&nd, dfd, name); 2694c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26952d864651SAl Viro if (unlikely(error == -ECHILD)) 2696c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26972d864651SAl Viro if (unlikely(error == -ESTALE)) 2698c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26992d864651SAl Viro if (likely(!error)) 2700668696dcSAl Viro audit_inode(name, path->dentry, 0); 27019883d185SAl Viro restore_nameidata(); 2702668696dcSAl Viro putname(name); 27032d864651SAl Viro return error; 27042d864651SAl Viro } 27052d864651SAl Viro 27068033426eSJeff Layton /** 2707197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 27088033426eSJeff Layton * @dfd: directory file descriptor 27098033426eSJeff Layton * @name: pathname from userland 27108033426eSJeff Layton * @flags: lookup flags 27118033426eSJeff Layton * @path: pointer to container to hold result 27128033426eSJeff Layton * 27138033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 27148033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 27158033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 27168033426eSJeff Layton * and avoid revalidating the last component. 27178033426eSJeff Layton * 27188033426eSJeff Layton * Returns 0 and populates "path" on success. 27198033426eSJeff Layton */ 27208033426eSJeff Layton int 2721197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27228033426eSJeff Layton struct path *path) 27238033426eSJeff Layton { 2724cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27258033426eSJeff Layton } 27268033426eSJeff Layton 27272d864651SAl Viro int 27282d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27292d864651SAl Viro unsigned int flags) 27302d864651SAl Viro { 2731cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27322d864651SAl Viro } 27332d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27342d864651SAl Viro 2735cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27361da177e4SLinus Torvalds { 27378e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2738da9592edSDavid Howells 27398e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27401da177e4SLinus Torvalds return 0; 27418e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27421da177e4SLinus Torvalds return 0; 274323adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27441da177e4SLinus Torvalds } 2745cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27461da177e4SLinus Torvalds 27471da177e4SLinus Torvalds /* 27481da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27491da177e4SLinus Torvalds * whether the type of victim is right. 27501da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27511da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27521da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27531da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27541da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27551da177e4SLinus Torvalds * a. be owner of dir, or 27561da177e4SLinus Torvalds * b. be owner of victim, or 27571da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27581da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27591da177e4SLinus Torvalds * links pointing to it. 27600bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27610bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27620bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27630bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27640bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27651da177e4SLinus Torvalds * nfs_async_unlink(). 27661da177e4SLinus Torvalds */ 2767b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27681da177e4SLinus Torvalds { 276963afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27701da177e4SLinus Torvalds int error; 27711da177e4SLinus Torvalds 2772b18825a7SDavid Howells if (d_is_negative(victim)) 27731da177e4SLinus Torvalds return -ENOENT; 2774b18825a7SDavid Howells BUG_ON(!inode); 27751da177e4SLinus Torvalds 27761da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27774fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27781da177e4SLinus Torvalds 2779f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27801da177e4SLinus Torvalds if (error) 27811da177e4SLinus Torvalds return error; 27821da177e4SLinus Torvalds if (IS_APPEND(dir)) 27831da177e4SLinus Torvalds return -EPERM; 2784b18825a7SDavid Howells 2785b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27860bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27871da177e4SLinus Torvalds return -EPERM; 27881da177e4SLinus Torvalds if (isdir) { 278944b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27901da177e4SLinus Torvalds return -ENOTDIR; 27911da177e4SLinus Torvalds if (IS_ROOT(victim)) 27921da177e4SLinus Torvalds return -EBUSY; 279344b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27941da177e4SLinus Torvalds return -EISDIR; 27951da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27961da177e4SLinus Torvalds return -ENOENT; 27971da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27981da177e4SLinus Torvalds return -EBUSY; 27991da177e4SLinus Torvalds return 0; 28001da177e4SLinus Torvalds } 28011da177e4SLinus Torvalds 28021da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 28031da177e4SLinus Torvalds * dir. 28041da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 28051da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 28061da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2807036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2808036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2809036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 28101da177e4SLinus Torvalds */ 2811a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 28121da177e4SLinus Torvalds { 2813036d5236SEric W. Biederman struct user_namespace *s_user_ns; 281414e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 28151da177e4SLinus Torvalds if (child->d_inode) 28161da177e4SLinus Torvalds return -EEXIST; 28171da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 28181da177e4SLinus Torvalds return -ENOENT; 2819036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2820036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2821036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2822036d5236SEric W. Biederman return -EOVERFLOW; 2823f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28241da177e4SLinus Torvalds } 28251da177e4SLinus Torvalds 28261da177e4SLinus Torvalds /* 28271da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28281da177e4SLinus Torvalds */ 28291da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28301da177e4SLinus Torvalds { 28311da177e4SLinus Torvalds struct dentry *p; 28321da177e4SLinus Torvalds 28331da177e4SLinus Torvalds if (p1 == p2) { 28345955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28351da177e4SLinus Torvalds return NULL; 28361da177e4SLinus Torvalds } 28371da177e4SLinus Torvalds 2838fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28391da177e4SLinus Torvalds 2840e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2841e2761a11SOGAWA Hirofumi if (p) { 28425955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28435955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28441da177e4SLinus Torvalds return p; 28451da177e4SLinus Torvalds } 28461da177e4SLinus Torvalds 2847e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2848e2761a11SOGAWA Hirofumi if (p) { 28495955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28505955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28511da177e4SLinus Torvalds return p; 28521da177e4SLinus Torvalds } 28531da177e4SLinus Torvalds 28545955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28555955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28561da177e4SLinus Torvalds return NULL; 28571da177e4SLinus Torvalds } 28584d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28591da177e4SLinus Torvalds 28601da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28611da177e4SLinus Torvalds { 28625955102cSAl Viro inode_unlock(p1->d_inode); 28631da177e4SLinus Torvalds if (p1 != p2) { 28645955102cSAl Viro inode_unlock(p2->d_inode); 2865fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28661da177e4SLinus Torvalds } 28671da177e4SLinus Torvalds } 28684d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28691da177e4SLinus Torvalds 28704acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2871312b63fbSAl Viro bool want_excl) 28721da177e4SLinus Torvalds { 2873a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28741da177e4SLinus Torvalds if (error) 28751da177e4SLinus Torvalds return error; 28761da177e4SLinus Torvalds 2877acfa4380SAl Viro if (!dir->i_op->create) 28781da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28791da177e4SLinus Torvalds mode &= S_IALLUGO; 28801da177e4SLinus Torvalds mode |= S_IFREG; 28811da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28821da177e4SLinus Torvalds if (error) 28831da177e4SLinus Torvalds return error; 2884312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2885a74574aaSStephen Smalley if (!error) 2886f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28871da177e4SLinus Torvalds return error; 28881da177e4SLinus Torvalds } 28894d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28901da177e4SLinus Torvalds 2891a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2892a2982cc9SEric W. Biederman { 2893a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2894a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2895a2982cc9SEric W. Biederman } 2896a2982cc9SEric W. Biederman 2897f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28981da177e4SLinus Torvalds { 28993fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29001da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29011da177e4SLinus Torvalds int error; 29021da177e4SLinus Torvalds 29031da177e4SLinus Torvalds if (!inode) 29041da177e4SLinus Torvalds return -ENOENT; 29051da177e4SLinus Torvalds 2906c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2907c8fe8f30SChristoph Hellwig case S_IFLNK: 29081da177e4SLinus Torvalds return -ELOOP; 2909c8fe8f30SChristoph Hellwig case S_IFDIR: 2910c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29111da177e4SLinus Torvalds return -EISDIR; 2912c8fe8f30SChristoph Hellwig break; 2913c8fe8f30SChristoph Hellwig case S_IFBLK: 2914c8fe8f30SChristoph Hellwig case S_IFCHR: 2915a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29161da177e4SLinus Torvalds return -EACCES; 2917c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2918c8fe8f30SChristoph Hellwig case S_IFIFO: 2919c8fe8f30SChristoph Hellwig case S_IFSOCK: 29201da177e4SLinus Torvalds flag &= ~O_TRUNC; 2921c8fe8f30SChristoph Hellwig break; 29224a3fd211SDave Hansen } 2923b41572e9SDave Hansen 292462fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2925b41572e9SDave Hansen if (error) 2926b41572e9SDave Hansen return error; 29276146f0d5SMimi Zohar 29281da177e4SLinus Torvalds /* 29291da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29301da177e4SLinus Torvalds */ 29311da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29328737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29337715b521SAl Viro return -EPERM; 29341da177e4SLinus Torvalds if (flag & O_TRUNC) 29357715b521SAl Viro return -EPERM; 29361da177e4SLinus Torvalds } 29371da177e4SLinus Torvalds 29381da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29392e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29407715b521SAl Viro return -EPERM; 29411da177e4SLinus Torvalds 2942f3c7691eSJ. Bruce Fields return 0; 29437715b521SAl Viro } 29447715b521SAl Viro 2945e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29467715b521SAl Viro { 2947f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29487715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29497715b521SAl Viro int error = get_write_access(inode); 29501da177e4SLinus Torvalds if (error) 29517715b521SAl Viro return error; 29521da177e4SLinus Torvalds /* 29531da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29541da177e4SLinus Torvalds */ 2955d7a06983SJeff Layton error = locks_verify_locked(filp); 2956be6d3e56SKentaro Takeda if (!error) 2957ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29581da177e4SLinus Torvalds if (!error) { 29597715b521SAl Viro error = do_truncate(path->dentry, 0, 2960d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2961e1181ee6SJeff Layton filp); 29621da177e4SLinus Torvalds } 29631da177e4SLinus Torvalds put_write_access(inode); 2964acd0c935SMimi Zohar return error; 29651da177e4SLinus Torvalds } 29661da177e4SLinus Torvalds 2967d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2968d57999e1SDave Hansen { 29698a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29708a5e929dSAl Viro flag--; 2971d57999e1SDave Hansen return flag; 2972d57999e1SDave Hansen } 2973d57999e1SDave Hansen 2974d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2975d18e9008SMiklos Szeredi { 29761328c727SSeth Forshee struct user_namespace *s_user_ns; 2977d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2978d18e9008SMiklos Szeredi if (error) 2979d18e9008SMiklos Szeredi return error; 2980d18e9008SMiklos Szeredi 29811328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29821328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29831328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29841328c727SSeth Forshee return -EOVERFLOW; 29851328c727SSeth Forshee 2986d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2987d18e9008SMiklos Szeredi if (error) 2988d18e9008SMiklos Szeredi return error; 2989d18e9008SMiklos Szeredi 2990d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2991d18e9008SMiklos Szeredi } 2992d18e9008SMiklos Szeredi 29931acf0af9SDavid Howells /* 29941acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29951acf0af9SDavid Howells * dentry. 29961acf0af9SDavid Howells * 29971acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29981acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29991acf0af9SDavid Howells * 30001acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 30011acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 30021acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 30031acf0af9SDavid Howells * 30041acf0af9SDavid Howells * Returns an error code otherwise. 30051acf0af9SDavid Howells */ 30062675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 300730d90494SAl Viro struct path *path, struct file *file, 3008015c3bbcSMiklos Szeredi const struct open_flags *op, 30091643b43fSAl Viro int open_flag, umode_t mode, 301047237687SAl Viro int *opened) 3011d18e9008SMiklos Szeredi { 3012d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3013d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3014d18e9008SMiklos Szeredi int error; 3015d18e9008SMiklos Szeredi 3016384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3017d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3018d18e9008SMiklos Szeredi 3019d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3020d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3021d18e9008SMiklos Szeredi 302230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 302330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30240fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30250fb1ea09SAl Viro open_to_namei_flags(open_flag), 30260fb1ea09SAl Viro mode, opened); 30276fbd0714SAl Viro d_lookup_done(dentry); 3028384f26e2SAl Viro if (!error) { 3029d18e9008SMiklos Szeredi /* 3030384f26e2SAl Viro * We didn't have the inode before the open, so check open 3031384f26e2SAl Viro * permission here. 3032d18e9008SMiklos Szeredi */ 3033384f26e2SAl Viro int acc_mode = op->acc_mode; 303403da633aSAl Viro if (*opened & FILE_CREATED) { 303503da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 303603da633aSAl Viro fsnotify_create(dir, dentry); 303762fb4a15SAl Viro acc_mode = 0; 303803da633aSAl Viro } 30392675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3040384f26e2SAl Viro if (WARN_ON(error > 0)) 3041384f26e2SAl Viro error = -EINVAL; 3042384f26e2SAl Viro } else if (error > 0) { 3043d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3044d18e9008SMiklos Szeredi error = -EIO; 3045384f26e2SAl Viro } else { 3046d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3047d18e9008SMiklos Szeredi dput(dentry); 3048d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 304910c64ceaSAl Viro } 3050d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3051d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3052a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3053a01e718fSAl Viro error = -ENOENT; 3054a01e718fSAl Viro } else { 3055d18e9008SMiklos Szeredi path->dentry = dentry; 3056d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30572675a4ebSAl Viro return 1; 3058d18e9008SMiklos Szeredi } 3059d18e9008SMiklos Szeredi } 3060a01e718fSAl Viro } 3061d18e9008SMiklos Szeredi dput(dentry); 3062d18e9008SMiklos Szeredi return error; 3063d18e9008SMiklos Szeredi } 3064d18e9008SMiklos Szeredi 306531e6b01fSNick Piggin /* 30661acf0af9SDavid Howells * Look up and maybe create and open the last component. 3067d58ffd35SMiklos Szeredi * 3068d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3069d58ffd35SMiklos Szeredi * 30701acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30711acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30721acf0af9SDavid Howells * 30731acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30741acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30751acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30761acf0af9SDavid Howells * specified then a negative dentry may be returned. 30771acf0af9SDavid Howells * 30781acf0af9SDavid Howells * An error code is returned otherwise. 30791acf0af9SDavid Howells * 30801acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30811acf0af9SDavid Howells * cleared otherwise prior to returning. 3082d58ffd35SMiklos Szeredi */ 30832675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 308430d90494SAl Viro struct file *file, 3085d58ffd35SMiklos Szeredi const struct open_flags *op, 308664894cf8SAl Viro bool got_write, int *opened) 3087d58ffd35SMiklos Szeredi { 3088d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 308954ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30901643b43fSAl Viro int open_flag = op->open_flag; 3091d58ffd35SMiklos Szeredi struct dentry *dentry; 30921643b43fSAl Viro int error, create_error = 0; 30931643b43fSAl Viro umode_t mode = op->mode; 30946fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3095d58ffd35SMiklos Szeredi 3096ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3097ce8644fcSAl Viro return -ENOENT; 3098d58ffd35SMiklos Szeredi 309947237687SAl Viro *opened &= ~FILE_CREATED; 31006fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 31016fbd0714SAl Viro for (;;) { 31026fbd0714SAl Viro if (!dentry) { 31036fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3104d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31052675a4ebSAl Viro return PTR_ERR(dentry); 31066fbd0714SAl Viro } 31076fbd0714SAl Viro if (d_in_lookup(dentry)) 31086fbd0714SAl Viro break; 3109d58ffd35SMiklos Szeredi 31106fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31116fbd0714SAl Viro if (likely(error > 0)) 31126fbd0714SAl Viro break; 31136fbd0714SAl Viro if (error) 31146fbd0714SAl Viro goto out_dput; 31156fbd0714SAl Viro d_invalidate(dentry); 31166fbd0714SAl Viro dput(dentry); 31176fbd0714SAl Viro dentry = NULL; 31186fbd0714SAl Viro } 31196fbd0714SAl Viro if (dentry->d_inode) { 3120d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3121d18e9008SMiklos Szeredi goto out_no_open; 31226c51e513SAl Viro } 3123d18e9008SMiklos Szeredi 31241643b43fSAl Viro /* 31251643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31261643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31271643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31281643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31291643b43fSAl Viro * 31301643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31311643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31321643b43fSAl Viro */ 31331643b43fSAl Viro if (open_flag & O_CREAT) { 31341643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31351643b43fSAl Viro mode &= ~current_umask(); 31361643b43fSAl Viro if (unlikely(!got_write)) { 31371643b43fSAl Viro create_error = -EROFS; 31381643b43fSAl Viro open_flag &= ~O_CREAT; 31391643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31401643b43fSAl Viro goto no_open; 31411643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31421643b43fSAl Viro } else { 31431643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31441643b43fSAl Viro if (create_error) { 31451643b43fSAl Viro open_flag &= ~O_CREAT; 31461643b43fSAl Viro if (open_flag & O_EXCL) 31471643b43fSAl Viro goto no_open; 31481643b43fSAl Viro } 31491643b43fSAl Viro } 31501643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31511643b43fSAl Viro unlikely(!got_write)) { 31521643b43fSAl Viro /* 31531643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31541643b43fSAl Viro * back to lookup + open 31551643b43fSAl Viro */ 31561643b43fSAl Viro goto no_open; 3157d18e9008SMiklos Szeredi } 3158d18e9008SMiklos Szeredi 31591643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31601643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31611643b43fSAl Viro mode, opened); 31621643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31631643b43fSAl Viro error = create_error; 31641643b43fSAl Viro return error; 31651643b43fSAl Viro } 316654ef4872SMiklos Szeredi 31671643b43fSAl Viro no_open: 31686fbd0714SAl Viro if (d_in_lookup(dentry)) { 316912fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 317012fa5e24SAl Viro nd->flags); 31716fbd0714SAl Viro d_lookup_done(dentry); 317212fa5e24SAl Viro if (unlikely(res)) { 317312fa5e24SAl Viro if (IS_ERR(res)) { 317412fa5e24SAl Viro error = PTR_ERR(res); 317512fa5e24SAl Viro goto out_dput; 317612fa5e24SAl Viro } 317712fa5e24SAl Viro dput(dentry); 317812fa5e24SAl Viro dentry = res; 317912fa5e24SAl Viro } 318054ef4872SMiklos Szeredi } 318154ef4872SMiklos Szeredi 3182d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31831643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 318447237687SAl Viro *opened |= FILE_CREATED; 3185ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3186ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3187ce8644fcSAl Viro error = -EACCES; 3188d58ffd35SMiklos Szeredi goto out_dput; 318977d660a8SMiklos Szeredi } 3190ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31911643b43fSAl Viro open_flag & O_EXCL); 3192d58ffd35SMiklos Szeredi if (error) 3193d58ffd35SMiklos Szeredi goto out_dput; 3194ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3195d58ffd35SMiklos Szeredi } 31961643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31971643b43fSAl Viro error = create_error; 3198d58ffd35SMiklos Szeredi goto out_dput; 3199d58ffd35SMiklos Szeredi } 3200d18e9008SMiklos Szeredi out_no_open: 3201d58ffd35SMiklos Szeredi path->dentry = dentry; 3202d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 32032675a4ebSAl Viro return 1; 3204d58ffd35SMiklos Szeredi 3205d58ffd35SMiklos Szeredi out_dput: 3206d58ffd35SMiklos Szeredi dput(dentry); 32072675a4ebSAl Viro return error; 3208d58ffd35SMiklos Szeredi } 3209d58ffd35SMiklos Szeredi 3210d58ffd35SMiklos Szeredi /* 3211fe2d35ffSAl Viro * Handle the last step of open() 321231e6b01fSNick Piggin */ 3213896475d5SAl Viro static int do_last(struct nameidata *nd, 321430d90494SAl Viro struct file *file, const struct open_flags *op, 321576ae2a5aSAl Viro int *opened) 3216fb1cc555SAl Viro { 3217a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3218ca344a89SAl Viro int open_flag = op->open_flag; 321977d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 322064894cf8SAl Viro bool got_write = false; 3221bcda7652SAl Viro int acc_mode = op->acc_mode; 3222254cf582SAl Viro unsigned seq; 3223a1eb3315SMiklos Szeredi struct inode *inode; 3224896475d5SAl Viro struct path path; 322516c2cd71SAl Viro int error; 3226fb1cc555SAl Viro 3227c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3228c3e380b0SAl Viro nd->flags |= op->intent; 3229c3e380b0SAl Viro 3230bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3231fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3232deb106c6SAl Viro if (unlikely(error)) 32332675a4ebSAl Viro return error; 3234e83db167SMiklos Szeredi goto finish_open; 32351f36f774SAl Viro } 3236a2c36b45SAl Viro 3237ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3238fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3239fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3240fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3241254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3242e9742b53SAl Viro if (likely(error > 0)) 324371574865SMiklos Szeredi goto finish_lookup; 324471574865SMiklos Szeredi 3245ce57dfc1SAl Viro if (error < 0) 3246deb106c6SAl Viro return error; 3247a1eb3315SMiklos Szeredi 324837d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32496583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3250b6183df7SMiklos Szeredi } else { 3251fe2d35ffSAl Viro /* create side of things */ 3252a3fbbde7SAl Viro /* 3253b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3254b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3255b6183df7SMiklos Szeredi * about to look up 3256a3fbbde7SAl Viro */ 32579f1fafeeSAl Viro error = complete_walk(nd); 3258e8bb73dfSAl Viro if (error) 32592675a4ebSAl Viro return error; 3260fe2d35ffSAl Viro 326176ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32621f36f774SAl Viro /* trailing slashes? */ 3263deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3264deb106c6SAl Viro return -EISDIR; 3265b6183df7SMiklos Szeredi } 32661f36f774SAl Viro 32679cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 326864894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 326964894cf8SAl Viro if (!error) 327064894cf8SAl Viro got_write = true; 327164894cf8SAl Viro /* 327264894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 327364894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 327464894cf8SAl Viro * dropping this one anyway. 327564894cf8SAl Viro */ 327664894cf8SAl Viro } 32779cf843e3SAl Viro if (open_flag & O_CREAT) 32785955102cSAl Viro inode_lock(dir->d_inode); 32799cf843e3SAl Viro else 32809cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3281896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32829cf843e3SAl Viro if (open_flag & O_CREAT) 32835955102cSAl Viro inode_unlock(dir->d_inode); 32849cf843e3SAl Viro else 32859cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3286fb1cc555SAl Viro 32872675a4ebSAl Viro if (error <= 0) { 32882675a4ebSAl Viro if (error) 3289d58ffd35SMiklos Szeredi goto out; 32906c0d46c4SAl Viro 329147237687SAl Viro if ((*opened & FILE_CREATED) || 3292496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 329377d660a8SMiklos Szeredi will_truncate = false; 3294d18e9008SMiklos Szeredi 329576ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3296d18e9008SMiklos Szeredi goto opened; 3297d18e9008SMiklos Szeredi } 3298d18e9008SMiklos Szeredi 329947237687SAl Viro if (*opened & FILE_CREATED) { 33009b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3301ca344a89SAl Viro open_flag &= ~O_TRUNC; 330277d660a8SMiklos Szeredi will_truncate = false; 330362fb4a15SAl Viro acc_mode = 0; 3304896475d5SAl Viro path_to_nameidata(&path, nd); 3305e83db167SMiklos Szeredi goto finish_open_created; 3306fb1cc555SAl Viro } 3307fb1cc555SAl Viro 3308fb1cc555SAl Viro /* 3309d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3310d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3311d18e9008SMiklos Szeredi * necessary...) 3312d18e9008SMiklos Szeredi */ 331364894cf8SAl Viro if (got_write) { 3314d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 331564894cf8SAl Viro got_write = false; 3316d18e9008SMiklos Szeredi } 3317d18e9008SMiklos Szeredi 3318e6ec03a2SAl Viro error = follow_managed(&path, nd); 3319e6ec03a2SAl Viro if (unlikely(error < 0)) 3320e6ec03a2SAl Viro return error; 3321e6ec03a2SAl Viro 33226583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33236583fe22SAl Viro path_to_nameidata(&path, nd); 33246583fe22SAl Viro return -ENOENT; 33256583fe22SAl Viro } 33266583fe22SAl Viro 33276583fe22SAl Viro /* 33286583fe22SAl Viro * create/update audit record if it already exists. 33296583fe22SAl Viro */ 33306583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33316583fe22SAl Viro 3332deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3333deb106c6SAl Viro path_to_nameidata(&path, nd); 3334deb106c6SAl Viro return -EEXIST; 3335deb106c6SAl Viro } 3336fb1cc555SAl Viro 3337254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3338d4565649SAl Viro inode = d_backing_inode(path.dentry); 3339766c4cbfSAl Viro finish_lookup: 33408f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3341deb106c6SAl Viro if (unlikely(error)) 3342d63ff28fSAl Viro return error; 3343bc77daa7SAl Viro finish_open: 33448f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3345a3fbbde7SAl Viro error = complete_walk(nd); 3346fac7d191SAl Viro if (error) 33472675a4ebSAl Viro return error; 334876ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3349fb1cc555SAl Viro error = -EISDIR; 335044b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33512675a4ebSAl Viro goto out; 3352af2f5542SMiklos Szeredi error = -ENOTDIR; 335344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33542675a4ebSAl Viro goto out; 33554bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 335677d660a8SMiklos Szeredi will_truncate = false; 33576c0d46c4SAl Viro 33580f9d1a10SAl Viro if (will_truncate) { 33590f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33600f9d1a10SAl Viro if (error) 33612675a4ebSAl Viro goto out; 336264894cf8SAl Viro got_write = true; 33630f9d1a10SAl Viro } 3364e83db167SMiklos Szeredi finish_open_created: 3365bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3366ca344a89SAl Viro if (error) 33672675a4ebSAl Viro goto out; 33684aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33694aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3370fac7d191SAl Viro if (error) 3371015c3bbcSMiklos Szeredi goto out; 3372fac7d191SAl Viro *opened |= FILE_OPENED; 3373a8277b9bSMiklos Szeredi opened: 33742675a4ebSAl Viro error = open_check_o_direct(file); 3375fe9ec829SAl Viro if (!error) 33763034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3377fe9ec829SAl Viro if (!error && will_truncate) 33782675a4ebSAl Viro error = handle_truncate(file); 3379ca344a89SAl Viro out: 3380fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3381fe9ec829SAl Viro fput(file); 3382c80567c8SAl Viro if (unlikely(error > 0)) { 3383c80567c8SAl Viro WARN_ON(1); 3384c80567c8SAl Viro error = -EINVAL; 3385c80567c8SAl Viro } 338664894cf8SAl Viro if (got_write) 33870f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33882675a4ebSAl Viro return error; 3389fb1cc555SAl Viro } 3390fb1cc555SAl Viro 3391af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3392af7bd4dcSAmir Goldstein { 3393af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3394af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3395af7bd4dcSAmir Goldstein struct inode *inode; 3396af7bd4dcSAmir Goldstein int error; 3397af7bd4dcSAmir Goldstein 3398af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3399af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3400af7bd4dcSAmir Goldstein if (error) 3401af7bd4dcSAmir Goldstein goto out_err; 3402af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3403af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3404af7bd4dcSAmir Goldstein goto out_err; 3405af7bd4dcSAmir Goldstein error = -ENOMEM; 3406cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3407af7bd4dcSAmir Goldstein if (unlikely(!child)) 3408af7bd4dcSAmir Goldstein goto out_err; 3409af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3410af7bd4dcSAmir Goldstein if (error) 3411af7bd4dcSAmir Goldstein goto out_err; 3412af7bd4dcSAmir Goldstein error = -ENOENT; 3413af7bd4dcSAmir Goldstein inode = child->d_inode; 3414af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3415af7bd4dcSAmir Goldstein goto out_err; 3416af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3417af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3418af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3419af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3420af7bd4dcSAmir Goldstein } 3421af7bd4dcSAmir Goldstein return child; 3422af7bd4dcSAmir Goldstein 3423af7bd4dcSAmir Goldstein out_err: 3424af7bd4dcSAmir Goldstein dput(child); 3425af7bd4dcSAmir Goldstein return ERR_PTR(error); 3426af7bd4dcSAmir Goldstein } 3427af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3428af7bd4dcSAmir Goldstein 3429c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 343060545d0dSAl Viro const struct open_flags *op, 343160545d0dSAl Viro struct file *file, int *opened) 343260545d0dSAl Viro { 3433625b6d10SAl Viro struct dentry *child; 3434625b6d10SAl Viro struct path path; 3435c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 343660545d0dSAl Viro if (unlikely(error)) 343760545d0dSAl Viro return error; 3438625b6d10SAl Viro error = mnt_want_write(path.mnt); 343960545d0dSAl Viro if (unlikely(error)) 344060545d0dSAl Viro goto out; 3441af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3442af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3443684e73beSHirofumi Nakagawa if (IS_ERR(child)) 344460545d0dSAl Viro goto out2; 3445625b6d10SAl Viro dput(path.dentry); 3446625b6d10SAl Viro path.dentry = child; 3447c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 344869a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 344962fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 345060545d0dSAl Viro if (error) 345160545d0dSAl Viro goto out2; 3452625b6d10SAl Viro file->f_path.mnt = path.mnt; 3453625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 345460545d0dSAl Viro if (error) 345560545d0dSAl Viro goto out2; 345660545d0dSAl Viro error = open_check_o_direct(file); 3457af7bd4dcSAmir Goldstein if (error) 345860545d0dSAl Viro fput(file); 345960545d0dSAl Viro out2: 3460625b6d10SAl Viro mnt_drop_write(path.mnt); 346160545d0dSAl Viro out: 3462625b6d10SAl Viro path_put(&path); 346360545d0dSAl Viro return error; 346460545d0dSAl Viro } 346560545d0dSAl Viro 34666ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34676ac08709SAl Viro { 34686ac08709SAl Viro struct path path; 34696ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34706ac08709SAl Viro if (!error) { 34716ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34726ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34736ac08709SAl Viro path_put(&path); 34746ac08709SAl Viro } 34756ac08709SAl Viro return error; 34766ac08709SAl Viro } 34776ac08709SAl Viro 3478c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3479c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34801da177e4SLinus Torvalds { 3481368ee9baSAl Viro const char *s; 348230d90494SAl Viro struct file *file; 348347237687SAl Viro int opened = 0; 348413aab428SAl Viro int error; 348531e6b01fSNick Piggin 348630d90494SAl Viro file = get_empty_filp(); 34871afc99beSAl Viro if (IS_ERR(file)) 34881afc99beSAl Viro return file; 348931e6b01fSNick Piggin 349030d90494SAl Viro file->f_flags = op->open_flag; 349131e6b01fSNick Piggin 3492bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3493c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3494f15133dfSAl Viro goto out2; 349560545d0dSAl Viro } 349660545d0dSAl Viro 34976ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 34986ac08709SAl Viro error = do_o_path(nd, flags, file); 34996ac08709SAl Viro if (!error) 35006ac08709SAl Viro opened |= FILE_OPENED; 35016ac08709SAl Viro goto out2; 35026ac08709SAl Viro } 35036ac08709SAl Viro 3504c8a53ee5SAl Viro s = path_init(nd, flags); 3505368ee9baSAl Viro if (IS_ERR(s)) { 3506368ee9baSAl Viro put_filp(file); 3507368ee9baSAl Viro return ERR_CAST(s); 3508368ee9baSAl Viro } 35093bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 351076ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 351173d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35123bdba28bSAl Viro s = trailing_symlink(nd); 35133bdba28bSAl Viro if (IS_ERR(s)) { 35143bdba28bSAl Viro error = PTR_ERR(s); 35152675a4ebSAl Viro break; 3516806b681cSAl Viro } 35173bdba28bSAl Viro } 3518deb106c6SAl Viro terminate_walk(nd); 3519f15133dfSAl Viro out2: 35202675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35212675a4ebSAl Viro BUG_ON(!error); 352230d90494SAl Viro put_filp(file); 3523015c3bbcSMiklos Szeredi } 35242675a4ebSAl Viro if (unlikely(error)) { 35252675a4ebSAl Viro if (error == -EOPENSTALE) { 35262675a4ebSAl Viro if (flags & LOOKUP_RCU) 35272675a4ebSAl Viro error = -ECHILD; 35282675a4ebSAl Viro else 35292675a4ebSAl Viro error = -ESTALE; 35302675a4ebSAl Viro } 35312675a4ebSAl Viro file = ERR_PTR(error); 35322675a4ebSAl Viro } 35332675a4ebSAl Viro return file; 3534de459215SKirill Korotaev } 35351da177e4SLinus Torvalds 3536669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3537f9652e10SAl Viro const struct open_flags *op) 353813aab428SAl Viro { 35399883d185SAl Viro struct nameidata nd; 3540f9652e10SAl Viro int flags = op->lookup_flags; 354113aab428SAl Viro struct file *filp; 354213aab428SAl Viro 35439883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3544c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 354513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3546c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 354713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3548c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35499883d185SAl Viro restore_nameidata(); 355013aab428SAl Viro return filp; 355113aab428SAl Viro } 355213aab428SAl Viro 355373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3554f9652e10SAl Viro const char *name, const struct open_flags *op) 355573d049a4SAl Viro { 35569883d185SAl Viro struct nameidata nd; 355773d049a4SAl Viro struct file *file; 355851689104SPaul Moore struct filename *filename; 3559f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 356073d049a4SAl Viro 356173d049a4SAl Viro nd.root.mnt = mnt; 356273d049a4SAl Viro nd.root.dentry = dentry; 356373d049a4SAl Viro 3564b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 356573d049a4SAl Viro return ERR_PTR(-ELOOP); 356673d049a4SAl Viro 356751689104SPaul Moore filename = getname_kernel(name); 3568a1c83681SViresh Kumar if (IS_ERR(filename)) 356951689104SPaul Moore return ERR_CAST(filename); 357051689104SPaul Moore 35719883d185SAl Viro set_nameidata(&nd, -1, filename); 3572c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 357373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3574c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 357573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3576c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35779883d185SAl Viro restore_nameidata(); 357851689104SPaul Moore putname(filename); 357973d049a4SAl Viro return file; 358073d049a4SAl Viro } 358173d049a4SAl Viro 3582fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35831ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35841da177e4SLinus Torvalds { 3585c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3586391172c4SAl Viro struct qstr last; 3587391172c4SAl Viro int type; 3588c30dabfeSJan Kara int err2; 35891ac12b4bSJeff Layton int error; 35901ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35911ac12b4bSJeff Layton 35921ac12b4bSJeff Layton /* 35931ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35941ac12b4bSJeff Layton * other flags passed in are ignored! 35951ac12b4bSJeff Layton */ 35961ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35971ac12b4bSJeff Layton 35985c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35995c31b6ceSAl Viro if (IS_ERR(name)) 36005c31b6ceSAl Viro return ERR_CAST(name); 36011da177e4SLinus Torvalds 3602c663e5d8SChristoph Hellwig /* 3603c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3604c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3605c663e5d8SChristoph Hellwig */ 36065c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3607ed75e95dSAl Viro goto out; 3608c663e5d8SChristoph Hellwig 3609c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3610391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3611c663e5d8SChristoph Hellwig /* 3612c663e5d8SChristoph Hellwig * Do the final lookup. 3613c663e5d8SChristoph Hellwig */ 3614391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36155955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3616391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36171da177e4SLinus Torvalds if (IS_ERR(dentry)) 3618a8104a9fSAl Viro goto unlock; 3619c663e5d8SChristoph Hellwig 3620a8104a9fSAl Viro error = -EEXIST; 3621b18825a7SDavid Howells if (d_is_positive(dentry)) 3622a8104a9fSAl Viro goto fail; 3623b18825a7SDavid Howells 3624c663e5d8SChristoph Hellwig /* 3625c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3626c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3627c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3628c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3629c663e5d8SChristoph Hellwig */ 3630391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3631a8104a9fSAl Viro error = -ENOENT; 3632ed75e95dSAl Viro goto fail; 3633e9baf6e5SAl Viro } 3634c30dabfeSJan Kara if (unlikely(err2)) { 3635c30dabfeSJan Kara error = err2; 3636a8104a9fSAl Viro goto fail; 3637c30dabfeSJan Kara } 3638181c37b6SAl Viro putname(name); 3639e9baf6e5SAl Viro return dentry; 36401da177e4SLinus Torvalds fail: 3641a8104a9fSAl Viro dput(dentry); 3642a8104a9fSAl Viro dentry = ERR_PTR(error); 3643a8104a9fSAl Viro unlock: 36445955102cSAl Viro inode_unlock(path->dentry->d_inode); 3645c30dabfeSJan Kara if (!err2) 3646391172c4SAl Viro mnt_drop_write(path->mnt); 3647ed75e95dSAl Viro out: 3648391172c4SAl Viro path_put(path); 3649181c37b6SAl Viro putname(name); 3650ed75e95dSAl Viro return dentry; 3651dae6ad8fSAl Viro } 3652fa14a0b8SAl Viro 3653fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3654fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3655fa14a0b8SAl Viro { 3656181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3657181c37b6SAl Viro path, lookup_flags); 3658fa14a0b8SAl Viro } 3659dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3660dae6ad8fSAl Viro 3661921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3662921a1650SAl Viro { 3663921a1650SAl Viro dput(dentry); 36645955102cSAl Viro inode_unlock(path->dentry->d_inode); 3665a8104a9fSAl Viro mnt_drop_write(path->mnt); 3666921a1650SAl Viro path_put(path); 3667921a1650SAl Viro } 3668921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3669921a1650SAl Viro 3670520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36711ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3672dae6ad8fSAl Viro { 3673181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3674dae6ad8fSAl Viro } 3675dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3676dae6ad8fSAl Viro 36771a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36781da177e4SLinus Torvalds { 3679a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36801da177e4SLinus Torvalds 36811da177e4SLinus Torvalds if (error) 36821da177e4SLinus Torvalds return error; 36831da177e4SLinus Torvalds 3684975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36851da177e4SLinus Torvalds return -EPERM; 36861da177e4SLinus Torvalds 3687acfa4380SAl Viro if (!dir->i_op->mknod) 36881da177e4SLinus Torvalds return -EPERM; 36891da177e4SLinus Torvalds 369008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 369108ce5f16SSerge E. Hallyn if (error) 369208ce5f16SSerge E. Hallyn return error; 369308ce5f16SSerge E. Hallyn 36941da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36951da177e4SLinus Torvalds if (error) 36961da177e4SLinus Torvalds return error; 36971da177e4SLinus Torvalds 36981da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3699a74574aaSStephen Smalley if (!error) 3700f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37011da177e4SLinus Torvalds return error; 37021da177e4SLinus Torvalds } 37034d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37041da177e4SLinus Torvalds 3705f69aac00SAl Viro static int may_mknod(umode_t mode) 3706463c3197SDave Hansen { 3707463c3197SDave Hansen switch (mode & S_IFMT) { 3708463c3197SDave Hansen case S_IFREG: 3709463c3197SDave Hansen case S_IFCHR: 3710463c3197SDave Hansen case S_IFBLK: 3711463c3197SDave Hansen case S_IFIFO: 3712463c3197SDave Hansen case S_IFSOCK: 3713463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3714463c3197SDave Hansen return 0; 3715463c3197SDave Hansen case S_IFDIR: 3716463c3197SDave Hansen return -EPERM; 3717463c3197SDave Hansen default: 3718463c3197SDave Hansen return -EINVAL; 3719463c3197SDave Hansen } 3720463c3197SDave Hansen } 3721463c3197SDave Hansen 37228208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37232e4d0924SHeiko Carstens unsigned, dev) 37241da177e4SLinus Torvalds { 37251da177e4SLinus Torvalds struct dentry *dentry; 3726dae6ad8fSAl Viro struct path path; 3727dae6ad8fSAl Viro int error; 3728972567f1SJeff Layton unsigned int lookup_flags = 0; 37291da177e4SLinus Torvalds 37308e4bfca1SAl Viro error = may_mknod(mode); 37318e4bfca1SAl Viro if (error) 37328e4bfca1SAl Viro return error; 3733972567f1SJeff Layton retry: 3734972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3735dae6ad8fSAl Viro if (IS_ERR(dentry)) 3736dae6ad8fSAl Viro return PTR_ERR(dentry); 37372ad94ae6SAl Viro 3738dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3739ce3b0f8dSAl Viro mode &= ~current_umask(); 3740dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3741be6d3e56SKentaro Takeda if (error) 3742a8104a9fSAl Viro goto out; 37431da177e4SLinus Torvalds switch (mode & S_IFMT) { 37441da177e4SLinus Torvalds case 0: case S_IFREG: 3745312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 374605d1a717SMimi Zohar if (!error) 374705d1a717SMimi Zohar ima_post_path_mknod(dentry); 37481da177e4SLinus Torvalds break; 37491da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3750dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37511da177e4SLinus Torvalds new_decode_dev(dev)); 37521da177e4SLinus Torvalds break; 37531da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3754dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37551da177e4SLinus Torvalds break; 37561da177e4SLinus Torvalds } 3757a8104a9fSAl Viro out: 3758921a1650SAl Viro done_path_create(&path, dentry); 3759972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3760972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3761972567f1SJeff Layton goto retry; 3762972567f1SJeff Layton } 37631da177e4SLinus Torvalds return error; 37641da177e4SLinus Torvalds } 37651da177e4SLinus Torvalds 37668208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37675590ff0dSUlrich Drepper { 37685590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37695590ff0dSUlrich Drepper } 37705590ff0dSUlrich Drepper 377118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37721da177e4SLinus Torvalds { 3773a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37748de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37751da177e4SLinus Torvalds 37761da177e4SLinus Torvalds if (error) 37771da177e4SLinus Torvalds return error; 37781da177e4SLinus Torvalds 3779acfa4380SAl Viro if (!dir->i_op->mkdir) 37801da177e4SLinus Torvalds return -EPERM; 37811da177e4SLinus Torvalds 37821da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37831da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37841da177e4SLinus Torvalds if (error) 37851da177e4SLinus Torvalds return error; 37861da177e4SLinus Torvalds 37878de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37888de52778SAl Viro return -EMLINK; 37898de52778SAl Viro 37901da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3791a74574aaSStephen Smalley if (!error) 3792f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37931da177e4SLinus Torvalds return error; 37941da177e4SLinus Torvalds } 37954d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37961da177e4SLinus Torvalds 3797a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37981da177e4SLinus Torvalds { 37996902d925SDave Hansen struct dentry *dentry; 3800dae6ad8fSAl Viro struct path path; 3801dae6ad8fSAl Viro int error; 3802b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38031da177e4SLinus Torvalds 3804b76d8b82SJeff Layton retry: 3805b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38066902d925SDave Hansen if (IS_ERR(dentry)) 3807dae6ad8fSAl Viro return PTR_ERR(dentry); 38086902d925SDave Hansen 3809dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3810ce3b0f8dSAl Viro mode &= ~current_umask(); 3811dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3812a8104a9fSAl Viro if (!error) 3813dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3814921a1650SAl Viro done_path_create(&path, dentry); 3815b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3816b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3817b76d8b82SJeff Layton goto retry; 3818b76d8b82SJeff Layton } 38191da177e4SLinus Torvalds return error; 38201da177e4SLinus Torvalds } 38211da177e4SLinus Torvalds 3822a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38235590ff0dSUlrich Drepper { 38245590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38255590ff0dSUlrich Drepper } 38265590ff0dSUlrich Drepper 38271da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38281da177e4SLinus Torvalds { 38291da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38301da177e4SLinus Torvalds 38311da177e4SLinus Torvalds if (error) 38321da177e4SLinus Torvalds return error; 38331da177e4SLinus Torvalds 3834acfa4380SAl Viro if (!dir->i_op->rmdir) 38351da177e4SLinus Torvalds return -EPERM; 38361da177e4SLinus Torvalds 38371d2ef590SAl Viro dget(dentry); 38385955102cSAl Viro inode_lock(dentry->d_inode); 3839912dbc15SSage Weil 38401da177e4SLinus Torvalds error = -EBUSY; 38417af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3842912dbc15SSage Weil goto out; 3843912dbc15SSage Weil 38441da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3845912dbc15SSage Weil if (error) 3846912dbc15SSage Weil goto out; 3847912dbc15SSage Weil 38483cebde24SSage Weil shrink_dcache_parent(dentry); 38491da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3850912dbc15SSage Weil if (error) 3851912dbc15SSage Weil goto out; 3852912dbc15SSage Weil 38531da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3854d83c49f3SAl Viro dont_mount(dentry); 38558ed936b5SEric W. Biederman detach_mounts(dentry); 38561da177e4SLinus Torvalds 3857912dbc15SSage Weil out: 38585955102cSAl Viro inode_unlock(dentry->d_inode); 38591d2ef590SAl Viro dput(dentry); 3860912dbc15SSage Weil if (!error) 3861912dbc15SSage Weil d_delete(dentry); 38621da177e4SLinus Torvalds return error; 38631da177e4SLinus Torvalds } 38644d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38651da177e4SLinus Torvalds 38665590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38671da177e4SLinus Torvalds { 38681da177e4SLinus Torvalds int error = 0; 386991a27b2aSJeff Layton struct filename *name; 38701da177e4SLinus Torvalds struct dentry *dentry; 3871f5beed75SAl Viro struct path path; 3872f5beed75SAl Viro struct qstr last; 3873f5beed75SAl Viro int type; 3874c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3875c6ee9206SJeff Layton retry: 3876c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3877c1d4dd27SAl Viro &path, &last, &type); 387891a27b2aSJeff Layton if (IS_ERR(name)) 387991a27b2aSJeff Layton return PTR_ERR(name); 38801da177e4SLinus Torvalds 3881f5beed75SAl Viro switch (type) { 38821da177e4SLinus Torvalds case LAST_DOTDOT: 38831da177e4SLinus Torvalds error = -ENOTEMPTY; 38841da177e4SLinus Torvalds goto exit1; 38851da177e4SLinus Torvalds case LAST_DOT: 38861da177e4SLinus Torvalds error = -EINVAL; 38871da177e4SLinus Torvalds goto exit1; 38881da177e4SLinus Torvalds case LAST_ROOT: 38891da177e4SLinus Torvalds error = -EBUSY; 38901da177e4SLinus Torvalds goto exit1; 38911da177e4SLinus Torvalds } 38920612d9fbSOGAWA Hirofumi 3893f5beed75SAl Viro error = mnt_want_write(path.mnt); 3894c30dabfeSJan Kara if (error) 3895c30dabfeSJan Kara goto exit1; 38960612d9fbSOGAWA Hirofumi 38975955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3898f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38991da177e4SLinus Torvalds error = PTR_ERR(dentry); 39006902d925SDave Hansen if (IS_ERR(dentry)) 39016902d925SDave Hansen goto exit2; 3902e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3903e6bc45d6STheodore Ts'o error = -ENOENT; 3904e6bc45d6STheodore Ts'o goto exit3; 3905e6bc45d6STheodore Ts'o } 3906f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3907be6d3e56SKentaro Takeda if (error) 3908c30dabfeSJan Kara goto exit3; 3909f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39100622753bSDave Hansen exit3: 39111da177e4SLinus Torvalds dput(dentry); 39126902d925SDave Hansen exit2: 39135955102cSAl Viro inode_unlock(path.dentry->d_inode); 3914f5beed75SAl Viro mnt_drop_write(path.mnt); 39151da177e4SLinus Torvalds exit1: 3916f5beed75SAl Viro path_put(&path); 39171da177e4SLinus Torvalds putname(name); 3918c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3919c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3920c6ee9206SJeff Layton goto retry; 3921c6ee9206SJeff Layton } 39221da177e4SLinus Torvalds return error; 39231da177e4SLinus Torvalds } 39241da177e4SLinus Torvalds 39253cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39265590ff0dSUlrich Drepper { 39275590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39285590ff0dSUlrich Drepper } 39295590ff0dSUlrich Drepper 3930b21996e3SJ. Bruce Fields /** 3931b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3932b21996e3SJ. Bruce Fields * @dir: parent directory 3933b21996e3SJ. Bruce Fields * @dentry: victim 3934b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3935b21996e3SJ. Bruce Fields * 3936b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3937b21996e3SJ. Bruce Fields * 3938b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3939b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3940b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3941b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3942b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3943b21996e3SJ. Bruce Fields * 3944b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3945b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3946b21996e3SJ. Bruce Fields * to be NFS exported. 3947b21996e3SJ. Bruce Fields */ 3948b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39491da177e4SLinus Torvalds { 39509accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39511da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39521da177e4SLinus Torvalds 39531da177e4SLinus Torvalds if (error) 39541da177e4SLinus Torvalds return error; 39551da177e4SLinus Torvalds 3956acfa4380SAl Viro if (!dir->i_op->unlink) 39571da177e4SLinus Torvalds return -EPERM; 39581da177e4SLinus Torvalds 39595955102cSAl Viro inode_lock(target); 39608ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39611da177e4SLinus Torvalds error = -EBUSY; 39621da177e4SLinus Torvalds else { 39631da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3964bec1052eSAl Viro if (!error) { 39655a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39665a14696cSJ. Bruce Fields if (error) 3967b21996e3SJ. Bruce Fields goto out; 39681da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39698ed936b5SEric W. Biederman if (!error) { 3970d83c49f3SAl Viro dont_mount(dentry); 39718ed936b5SEric W. Biederman detach_mounts(dentry); 39728ed936b5SEric W. Biederman } 3973bec1052eSAl Viro } 39741da177e4SLinus Torvalds } 3975b21996e3SJ. Bruce Fields out: 39765955102cSAl Viro inode_unlock(target); 39771da177e4SLinus Torvalds 39781da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39791da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39809accbb97SJ. Bruce Fields fsnotify_link_count(target); 39811da177e4SLinus Torvalds d_delete(dentry); 39821da177e4SLinus Torvalds } 39830eeca283SRobert Love 39841da177e4SLinus Torvalds return error; 39851da177e4SLinus Torvalds } 39864d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39871da177e4SLinus Torvalds 39881da177e4SLinus Torvalds /* 39891da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39901b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39911da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39921da177e4SLinus Torvalds * while waiting on the I/O. 39931da177e4SLinus Torvalds */ 3994da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39951da177e4SLinus Torvalds { 39962ad94ae6SAl Viro int error; 39971da177e4SLinus Torvalds struct dentry *dentry; 3998f5beed75SAl Viro struct path path; 3999f5beed75SAl Viro struct qstr last; 4000f5beed75SAl Viro int type; 40011da177e4SLinus Torvalds struct inode *inode = NULL; 4002b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40035d18f813SJeff Layton unsigned int lookup_flags = 0; 40045d18f813SJeff Layton retry: 4005da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 400691a27b2aSJeff Layton if (IS_ERR(name)) 400791a27b2aSJeff Layton return PTR_ERR(name); 40082ad94ae6SAl Viro 40091da177e4SLinus Torvalds error = -EISDIR; 4010f5beed75SAl Viro if (type != LAST_NORM) 40111da177e4SLinus Torvalds goto exit1; 40120612d9fbSOGAWA Hirofumi 4013f5beed75SAl Viro error = mnt_want_write(path.mnt); 4014c30dabfeSJan Kara if (error) 4015c30dabfeSJan Kara goto exit1; 4016b21996e3SJ. Bruce Fields retry_deleg: 40175955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4018f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40191da177e4SLinus Torvalds error = PTR_ERR(dentry); 40201da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40211da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4022f5beed75SAl Viro if (last.name[last.len]) 402350338b88STörök Edwin goto slashes; 40241da177e4SLinus Torvalds inode = dentry->d_inode; 4025b18825a7SDavid Howells if (d_is_negative(dentry)) 4026e6bc45d6STheodore Ts'o goto slashes; 40277de9c6eeSAl Viro ihold(inode); 4028f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4029be6d3e56SKentaro Takeda if (error) 4030c30dabfeSJan Kara goto exit2; 4031f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40321da177e4SLinus Torvalds exit2: 40331da177e4SLinus Torvalds dput(dentry); 40341da177e4SLinus Torvalds } 40355955102cSAl Viro inode_unlock(path.dentry->d_inode); 40361da177e4SLinus Torvalds if (inode) 40371da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4038b21996e3SJ. Bruce Fields inode = NULL; 4039b21996e3SJ. Bruce Fields if (delegated_inode) { 40405a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4041b21996e3SJ. Bruce Fields if (!error) 4042b21996e3SJ. Bruce Fields goto retry_deleg; 4043b21996e3SJ. Bruce Fields } 4044f5beed75SAl Viro mnt_drop_write(path.mnt); 40451da177e4SLinus Torvalds exit1: 4046f5beed75SAl Viro path_put(&path); 40475d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40485d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40495d18f813SJeff Layton inode = NULL; 40505d18f813SJeff Layton goto retry; 40515d18f813SJeff Layton } 4052da2f1362SChristoph Hellwig putname(name); 40531da177e4SLinus Torvalds return error; 40541da177e4SLinus Torvalds 40551da177e4SLinus Torvalds slashes: 4056b18825a7SDavid Howells if (d_is_negative(dentry)) 4057b18825a7SDavid Howells error = -ENOENT; 405844b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4059b18825a7SDavid Howells error = -EISDIR; 4060b18825a7SDavid Howells else 4061b18825a7SDavid Howells error = -ENOTDIR; 40621da177e4SLinus Torvalds goto exit2; 40631da177e4SLinus Torvalds } 40641da177e4SLinus Torvalds 40652e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40665590ff0dSUlrich Drepper { 40675590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40685590ff0dSUlrich Drepper return -EINVAL; 40695590ff0dSUlrich Drepper 40705590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40715590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40725590ff0dSUlrich Drepper 4073da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40745590ff0dSUlrich Drepper } 40755590ff0dSUlrich Drepper 40763480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40775590ff0dSUlrich Drepper { 4078da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40795590ff0dSUlrich Drepper } 40805590ff0dSUlrich Drepper 4081db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40821da177e4SLinus Torvalds { 4083a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40841da177e4SLinus Torvalds 40851da177e4SLinus Torvalds if (error) 40861da177e4SLinus Torvalds return error; 40871da177e4SLinus Torvalds 4088acfa4380SAl Viro if (!dir->i_op->symlink) 40891da177e4SLinus Torvalds return -EPERM; 40901da177e4SLinus Torvalds 40911da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40921da177e4SLinus Torvalds if (error) 40931da177e4SLinus Torvalds return error; 40941da177e4SLinus Torvalds 40951da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4096a74574aaSStephen Smalley if (!error) 4097f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40981da177e4SLinus Torvalds return error; 40991da177e4SLinus Torvalds } 41004d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41011da177e4SLinus Torvalds 41022e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 41032e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41041da177e4SLinus Torvalds { 41052ad94ae6SAl Viro int error; 410691a27b2aSJeff Layton struct filename *from; 41076902d925SDave Hansen struct dentry *dentry; 4108dae6ad8fSAl Viro struct path path; 4109f46d3567SJeff Layton unsigned int lookup_flags = 0; 41101da177e4SLinus Torvalds 41111da177e4SLinus Torvalds from = getname(oldname); 41121da177e4SLinus Torvalds if (IS_ERR(from)) 41131da177e4SLinus Torvalds return PTR_ERR(from); 4114f46d3567SJeff Layton retry: 4115f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41161da177e4SLinus Torvalds error = PTR_ERR(dentry); 41176902d925SDave Hansen if (IS_ERR(dentry)) 4118dae6ad8fSAl Viro goto out_putname; 41196902d925SDave Hansen 412091a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4121a8104a9fSAl Viro if (!error) 412291a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4123921a1650SAl Viro done_path_create(&path, dentry); 4124f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4125f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4126f46d3567SJeff Layton goto retry; 4127f46d3567SJeff Layton } 41286902d925SDave Hansen out_putname: 41291da177e4SLinus Torvalds putname(from); 41301da177e4SLinus Torvalds return error; 41311da177e4SLinus Torvalds } 41321da177e4SLinus Torvalds 41333480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41345590ff0dSUlrich Drepper { 41355590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41365590ff0dSUlrich Drepper } 41375590ff0dSUlrich Drepper 4138146a8595SJ. Bruce Fields /** 4139146a8595SJ. Bruce Fields * vfs_link - create a new link 4140146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4141146a8595SJ. Bruce Fields * @dir: new parent 4142146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4143146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4144146a8595SJ. Bruce Fields * 4145146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4146146a8595SJ. Bruce Fields * 4147146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4148146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4149146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4150146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4151146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4152146a8595SJ. Bruce Fields * 4153146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4154146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4155146a8595SJ. Bruce Fields * to be NFS exported. 4156146a8595SJ. Bruce Fields */ 4157146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41581da177e4SLinus Torvalds { 41591da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41608de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41611da177e4SLinus Torvalds int error; 41621da177e4SLinus Torvalds 41631da177e4SLinus Torvalds if (!inode) 41641da177e4SLinus Torvalds return -ENOENT; 41651da177e4SLinus Torvalds 4166a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41671da177e4SLinus Torvalds if (error) 41681da177e4SLinus Torvalds return error; 41691da177e4SLinus Torvalds 41701da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41711da177e4SLinus Torvalds return -EXDEV; 41721da177e4SLinus Torvalds 41731da177e4SLinus Torvalds /* 41741da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41751da177e4SLinus Torvalds */ 41761da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41771da177e4SLinus Torvalds return -EPERM; 41780bd23d09SEric W. Biederman /* 41790bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41800bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41810bd23d09SEric W. Biederman * the vfs. 41820bd23d09SEric W. Biederman */ 41830bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41840bd23d09SEric W. Biederman return -EPERM; 4185acfa4380SAl Viro if (!dir->i_op->link) 41861da177e4SLinus Torvalds return -EPERM; 41877e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41881da177e4SLinus Torvalds return -EPERM; 41891da177e4SLinus Torvalds 41901da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41911da177e4SLinus Torvalds if (error) 41921da177e4SLinus Torvalds return error; 41931da177e4SLinus Torvalds 41945955102cSAl Viro inode_lock(inode); 4195aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4196f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4197aae8a97dSAneesh Kumar K.V error = -ENOENT; 41988de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41998de52778SAl Viro error = -EMLINK; 4200146a8595SJ. Bruce Fields else { 4201146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4202146a8595SJ. Bruce Fields if (!error) 42031da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4204146a8595SJ. Bruce Fields } 4205f4e0c30cSAl Viro 4206f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4207f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4208f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4209f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4210f4e0c30cSAl Viro } 42115955102cSAl Viro inode_unlock(inode); 4212e31e14ecSStephen Smalley if (!error) 42137e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42141da177e4SLinus Torvalds return error; 42151da177e4SLinus Torvalds } 42164d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42171da177e4SLinus Torvalds 42181da177e4SLinus Torvalds /* 42191da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42201da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42211da177e4SLinus Torvalds * newname. --KAB 42221da177e4SLinus Torvalds * 42231da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42241da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42251da177e4SLinus Torvalds * and other special files. --ADM 42261da177e4SLinus Torvalds */ 42272e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42282e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42291da177e4SLinus Torvalds { 42301da177e4SLinus Torvalds struct dentry *new_dentry; 4231dae6ad8fSAl Viro struct path old_path, new_path; 4232146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 423311a7b371SAneesh Kumar K.V int how = 0; 42341da177e4SLinus Torvalds int error; 42351da177e4SLinus Torvalds 423611a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4237c04030e1SUlrich Drepper return -EINVAL; 423811a7b371SAneesh Kumar K.V /* 4239f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4240f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4241f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 424211a7b371SAneesh Kumar K.V */ 4243f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4244f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4245f0cc6ffbSLinus Torvalds return -ENOENT; 424611a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4247f0cc6ffbSLinus Torvalds } 4248c04030e1SUlrich Drepper 424911a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 425011a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4251442e31caSJeff Layton retry: 425211a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42531da177e4SLinus Torvalds if (error) 42542ad94ae6SAl Viro return error; 42552ad94ae6SAl Viro 4256442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4257442e31caSJeff Layton (how & LOOKUP_REVAL)); 42581da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42596902d925SDave Hansen if (IS_ERR(new_dentry)) 4260dae6ad8fSAl Viro goto out; 4261dae6ad8fSAl Viro 4262dae6ad8fSAl Viro error = -EXDEV; 4263dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4264dae6ad8fSAl Viro goto out_dput; 4265800179c9SKees Cook error = may_linkat(&old_path); 4266800179c9SKees Cook if (unlikely(error)) 4267800179c9SKees Cook goto out_dput; 4268dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4269be6d3e56SKentaro Takeda if (error) 4270a8104a9fSAl Viro goto out_dput; 4271146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 427275c3f29dSDave Hansen out_dput: 4273921a1650SAl Viro done_path_create(&new_path, new_dentry); 4274146a8595SJ. Bruce Fields if (delegated_inode) { 4275146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4276d22e6338SOleg Drokin if (!error) { 4277d22e6338SOleg Drokin path_put(&old_path); 4278146a8595SJ. Bruce Fields goto retry; 4279146a8595SJ. Bruce Fields } 4280d22e6338SOleg Drokin } 4281442e31caSJeff Layton if (retry_estale(error, how)) { 4282d22e6338SOleg Drokin path_put(&old_path); 4283442e31caSJeff Layton how |= LOOKUP_REVAL; 4284442e31caSJeff Layton goto retry; 4285442e31caSJeff Layton } 42861da177e4SLinus Torvalds out: 42872d8f3038SAl Viro path_put(&old_path); 42881da177e4SLinus Torvalds 42891da177e4SLinus Torvalds return error; 42901da177e4SLinus Torvalds } 42911da177e4SLinus Torvalds 42923480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42935590ff0dSUlrich Drepper { 4294c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42955590ff0dSUlrich Drepper } 42965590ff0dSUlrich Drepper 4297bc27027aSMiklos Szeredi /** 4298bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4299bc27027aSMiklos Szeredi * @old_dir: parent of source 4300bc27027aSMiklos Szeredi * @old_dentry: source 4301bc27027aSMiklos Szeredi * @new_dir: parent of destination 4302bc27027aSMiklos Szeredi * @new_dentry: destination 4303bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4304520c8b16SMiklos Szeredi * @flags: rename flags 4305bc27027aSMiklos Szeredi * 4306bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4307bc27027aSMiklos Szeredi * 4308bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4309bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4310bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4311bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4312bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4313bc27027aSMiklos Szeredi * so. 4314bc27027aSMiklos Szeredi * 4315bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4316bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4317bc27027aSMiklos Szeredi * to be NFS exported. 4318bc27027aSMiklos Szeredi * 43191da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43201da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43211da177e4SLinus Torvalds * Problems: 43220117d427SMauro Carvalho Chehab * 4323d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43241da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43251da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4326a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43271da177e4SLinus Torvalds * story. 43286cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43296cedba89SJ. Bruce Fields * and source (if it is not a directory). 43301b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43311da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43321da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4333a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43341da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43351da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43361da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4337a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43381da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43391da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43401da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4341e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43421b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43431da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4344c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43451da177e4SLinus Torvalds * locking]. 43461da177e4SLinus Torvalds */ 43471da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43488e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4349520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43501da177e4SLinus Torvalds { 43511da177e4SLinus Torvalds int error; 4352bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4353bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4354bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4355da1ce067SMiklos Szeredi bool new_is_dir = false; 4356da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 435749d31c2fSAl Viro struct name_snapshot old_name; 43581da177e4SLinus Torvalds 43598d3e2936SMiklos Szeredi if (source == target) 43601da177e4SLinus Torvalds return 0; 43611da177e4SLinus Torvalds 43621da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43631da177e4SLinus Torvalds if (error) 43641da177e4SLinus Torvalds return error; 43651da177e4SLinus Torvalds 4366da1ce067SMiklos Szeredi if (!target) { 4367a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4368da1ce067SMiklos Szeredi } else { 4369da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4370da1ce067SMiklos Szeredi 4371da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43721da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4373da1ce067SMiklos Szeredi else 4374da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4375da1ce067SMiklos Szeredi } 43761da177e4SLinus Torvalds if (error) 43771da177e4SLinus Torvalds return error; 43781da177e4SLinus Torvalds 43792773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43801da177e4SLinus Torvalds return -EPERM; 43811da177e4SLinus Torvalds 4382bc27027aSMiklos Szeredi /* 4383bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4384bc27027aSMiklos Szeredi * we'll need to flip '..'. 4385bc27027aSMiklos Szeredi */ 4386da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4387da1ce067SMiklos Szeredi if (is_dir) { 4388bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4389bc27027aSMiklos Szeredi if (error) 4390bc27027aSMiklos Szeredi return error; 4391bc27027aSMiklos Szeredi } 4392da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4393da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4394da1ce067SMiklos Szeredi if (error) 4395da1ce067SMiklos Szeredi return error; 4396da1ce067SMiklos Szeredi } 4397da1ce067SMiklos Szeredi } 43980eeca283SRobert Love 43990b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44000b3974ebSMiklos Szeredi flags); 4401bc27027aSMiklos Szeredi if (error) 4402bc27027aSMiklos Szeredi return error; 4403bc27027aSMiklos Szeredi 440449d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4405bc27027aSMiklos Szeredi dget(new_dentry); 4406da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4407bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4408bc27027aSMiklos Szeredi else if (target) 44095955102cSAl Viro inode_lock(target); 4410bc27027aSMiklos Szeredi 4411bc27027aSMiklos Szeredi error = -EBUSY; 44127af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4413bc27027aSMiklos Szeredi goto out; 4414bc27027aSMiklos Szeredi 4415da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4416bc27027aSMiklos Szeredi error = -EMLINK; 4417da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4418bc27027aSMiklos Szeredi goto out; 4419da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4420da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4421da1ce067SMiklos Szeredi goto out; 4422da1ce067SMiklos Szeredi } 4423da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4424bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4425da1ce067SMiklos Szeredi if (!is_dir) { 4426bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4427bc27027aSMiklos Szeredi if (error) 4428bc27027aSMiklos Szeredi goto out; 4429da1ce067SMiklos Szeredi } 4430da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4431bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4432bc27027aSMiklos Szeredi if (error) 4433bc27027aSMiklos Szeredi goto out; 4434bc27027aSMiklos Szeredi } 4435520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4436520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4437bc27027aSMiklos Szeredi if (error) 4438bc27027aSMiklos Szeredi goto out; 4439bc27027aSMiklos Szeredi 4440da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44411da177e4SLinus Torvalds if (is_dir) 4442bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4443bc27027aSMiklos Szeredi dont_mount(new_dentry); 44448ed936b5SEric W. Biederman detach_mounts(new_dentry); 4445bc27027aSMiklos Szeredi } 4446da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4447da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4448bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4449da1ce067SMiklos Szeredi else 4450da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4451da1ce067SMiklos Szeredi } 4452bc27027aSMiklos Szeredi out: 4453da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4454bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4455bc27027aSMiklos Szeredi else if (target) 44565955102cSAl Viro inode_unlock(target); 4457bc27027aSMiklos Szeredi dput(new_dentry); 4458da1ce067SMiklos Szeredi if (!error) { 445949d31c2fSAl Viro fsnotify_move(old_dir, new_dir, old_name.name, is_dir, 4460da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4461da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4462da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4463da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4464da1ce067SMiklos Szeredi } 4465da1ce067SMiklos Szeredi } 446649d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44670eeca283SRobert Love 44681da177e4SLinus Torvalds return error; 44691da177e4SLinus Torvalds } 44704d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44711da177e4SLinus Torvalds 4472520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4473520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44741da177e4SLinus Torvalds { 44751da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44761da177e4SLinus Torvalds struct dentry *trap; 4477f5beed75SAl Viro struct path old_path, new_path; 4478f5beed75SAl Viro struct qstr old_last, new_last; 4479f5beed75SAl Viro int old_type, new_type; 44808e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 448191a27b2aSJeff Layton struct filename *from; 448291a27b2aSJeff Layton struct filename *to; 4483f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4484c6a94284SJeff Layton bool should_retry = false; 44852ad94ae6SAl Viro int error; 4486520c8b16SMiklos Szeredi 44870d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4488da1ce067SMiklos Szeredi return -EINVAL; 4489da1ce067SMiklos Szeredi 44900d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44910d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4492520c8b16SMiklos Szeredi return -EINVAL; 4493520c8b16SMiklos Szeredi 44940d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44950d7a8555SMiklos Szeredi return -EPERM; 44960d7a8555SMiklos Szeredi 4497f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4498f5beed75SAl Viro target_flags = 0; 4499f5beed75SAl Viro 4500c6a94284SJeff Layton retry: 4501c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4502c1d4dd27SAl Viro &old_path, &old_last, &old_type); 450391a27b2aSJeff Layton if (IS_ERR(from)) { 450491a27b2aSJeff Layton error = PTR_ERR(from); 45051da177e4SLinus Torvalds goto exit; 450691a27b2aSJeff Layton } 45071da177e4SLinus Torvalds 4508c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4509c1d4dd27SAl Viro &new_path, &new_last, &new_type); 451091a27b2aSJeff Layton if (IS_ERR(to)) { 451191a27b2aSJeff Layton error = PTR_ERR(to); 45121da177e4SLinus Torvalds goto exit1; 451391a27b2aSJeff Layton } 45141da177e4SLinus Torvalds 45151da177e4SLinus Torvalds error = -EXDEV; 4516f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45171da177e4SLinus Torvalds goto exit2; 45181da177e4SLinus Torvalds 45191da177e4SLinus Torvalds error = -EBUSY; 4520f5beed75SAl Viro if (old_type != LAST_NORM) 45211da177e4SLinus Torvalds goto exit2; 45221da177e4SLinus Torvalds 45230a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45240a7c3937SMiklos Szeredi error = -EEXIST; 4525f5beed75SAl Viro if (new_type != LAST_NORM) 45261da177e4SLinus Torvalds goto exit2; 45271da177e4SLinus Torvalds 4528f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4529c30dabfeSJan Kara if (error) 4530c30dabfeSJan Kara goto exit2; 4531c30dabfeSJan Kara 45328e6d782cSJ. Bruce Fields retry_deleg: 4533f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45341da177e4SLinus Torvalds 4535f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45361da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45371da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45381da177e4SLinus Torvalds goto exit3; 45391da177e4SLinus Torvalds /* source must exist */ 45401da177e4SLinus Torvalds error = -ENOENT; 4541b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45421da177e4SLinus Torvalds goto exit4; 4543f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45441da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45451da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45461da177e4SLinus Torvalds goto exit4; 45470a7c3937SMiklos Szeredi error = -EEXIST; 45480a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45490a7c3937SMiklos Szeredi goto exit5; 4550da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4551da1ce067SMiklos Szeredi error = -ENOENT; 4552da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4553da1ce067SMiklos Szeredi goto exit5; 4554da1ce067SMiklos Szeredi 4555da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4556da1ce067SMiklos Szeredi error = -ENOTDIR; 4557f5beed75SAl Viro if (new_last.name[new_last.len]) 4558da1ce067SMiklos Szeredi goto exit5; 4559da1ce067SMiklos Szeredi } 4560da1ce067SMiklos Szeredi } 45610a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45620a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45630a7c3937SMiklos Szeredi error = -ENOTDIR; 4564f5beed75SAl Viro if (old_last.name[old_last.len]) 45650a7c3937SMiklos Szeredi goto exit5; 4566f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45670a7c3937SMiklos Szeredi goto exit5; 45680a7c3937SMiklos Szeredi } 45690a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45700a7c3937SMiklos Szeredi error = -EINVAL; 45710a7c3937SMiklos Szeredi if (old_dentry == trap) 45720a7c3937SMiklos Szeredi goto exit5; 45731da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4574da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45751da177e4SLinus Torvalds error = -ENOTEMPTY; 45761da177e4SLinus Torvalds if (new_dentry == trap) 45771da177e4SLinus Torvalds goto exit5; 45781da177e4SLinus Torvalds 4579f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4580f5beed75SAl Viro &new_path, new_dentry, flags); 4581be6d3e56SKentaro Takeda if (error) 4582c30dabfeSJan Kara goto exit5; 4583f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4584f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4585520c8b16SMiklos Szeredi &delegated_inode, flags); 45861da177e4SLinus Torvalds exit5: 45871da177e4SLinus Torvalds dput(new_dentry); 45881da177e4SLinus Torvalds exit4: 45891da177e4SLinus Torvalds dput(old_dentry); 45901da177e4SLinus Torvalds exit3: 4591f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45928e6d782cSJ. Bruce Fields if (delegated_inode) { 45938e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45948e6d782cSJ. Bruce Fields if (!error) 45958e6d782cSJ. Bruce Fields goto retry_deleg; 45968e6d782cSJ. Bruce Fields } 4597f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45981da177e4SLinus Torvalds exit2: 4599c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4600c6a94284SJeff Layton should_retry = true; 4601f5beed75SAl Viro path_put(&new_path); 46022ad94ae6SAl Viro putname(to); 46031da177e4SLinus Torvalds exit1: 4604f5beed75SAl Viro path_put(&old_path); 46051da177e4SLinus Torvalds putname(from); 4606c6a94284SJeff Layton if (should_retry) { 4607c6a94284SJeff Layton should_retry = false; 4608c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4609c6a94284SJeff Layton goto retry; 4610c6a94284SJeff Layton } 46112ad94ae6SAl Viro exit: 46121da177e4SLinus Torvalds return error; 46131da177e4SLinus Torvalds } 46141da177e4SLinus Torvalds 4615520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4616520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4617520c8b16SMiklos Szeredi { 4618520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4619520c8b16SMiklos Szeredi } 4620520c8b16SMiklos Szeredi 4621a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46225590ff0dSUlrich Drepper { 4623520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46245590ff0dSUlrich Drepper } 46255590ff0dSUlrich Drepper 4626787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4627787fb6bcSMiklos Szeredi { 4628787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4629787fb6bcSMiklos Szeredi if (error) 4630787fb6bcSMiklos Szeredi return error; 4631787fb6bcSMiklos Szeredi 4632787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4633787fb6bcSMiklos Szeredi return -EPERM; 4634787fb6bcSMiklos Szeredi 4635787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4636787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4637787fb6bcSMiklos Szeredi } 4638787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4639787fb6bcSMiklos Szeredi 46405d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46411da177e4SLinus Torvalds { 46425d826c84SAl Viro int len = PTR_ERR(link); 46431da177e4SLinus Torvalds if (IS_ERR(link)) 46441da177e4SLinus Torvalds goto out; 46451da177e4SLinus Torvalds 46461da177e4SLinus Torvalds len = strlen(link); 46471da177e4SLinus Torvalds if (len > (unsigned) buflen) 46481da177e4SLinus Torvalds len = buflen; 46491da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46501da177e4SLinus Torvalds len = -EFAULT; 46511da177e4SLinus Torvalds out: 46521da177e4SLinus Torvalds return len; 46531da177e4SLinus Torvalds } 46541da177e4SLinus Torvalds 46551da177e4SLinus Torvalds /* 46561da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46576b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46586b255391SAl Viro * for any given inode is up to filesystem. 46591da177e4SLinus Torvalds */ 4660d16744ecSMiklos Szeredi static int generic_readlink(struct dentry *dentry, char __user *buffer, 4661d16744ecSMiklos Szeredi int buflen) 46621da177e4SLinus Torvalds { 4663fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46645f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46655f2c4179SAl Viro const char *link = inode->i_link; 4666694a1764SMarcin Slusarz int res; 4667cc314eefSLinus Torvalds 4668d4dee48bSAl Viro if (!link) { 4669fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4670680baacbSAl Viro if (IS_ERR(link)) 4671680baacbSAl Viro return PTR_ERR(link); 4672d4dee48bSAl Viro } 4673680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4674fceef393SAl Viro do_delayed_call(&done); 4675694a1764SMarcin Slusarz return res; 46761da177e4SLinus Torvalds } 46771da177e4SLinus Torvalds 4678d60874cdSMiklos Szeredi /** 4679fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4680fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4681fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4682fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4683fd4a0edfSMiklos Szeredi * 4684fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4685fd4a0edfSMiklos Szeredi * 4686fd4a0edfSMiklos Szeredi * Does not call security hook. 4687fd4a0edfSMiklos Szeredi */ 4688fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4689fd4a0edfSMiklos Szeredi { 4690fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4691fd4a0edfSMiklos Szeredi 469276fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 469376fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 469476fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 469576fca90eSMiklos Szeredi 469676fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4697fd4a0edfSMiklos Szeredi return -EINVAL; 4698fd4a0edfSMiklos Szeredi 469976fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 470076fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 470176fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 470276fca90eSMiklos Szeredi } 470376fca90eSMiklos Szeredi 470476fca90eSMiklos Szeredi return generic_readlink(dentry, buffer, buflen); 4705fd4a0edfSMiklos Szeredi } 4706fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 47071da177e4SLinus Torvalds 4708d60874cdSMiklos Szeredi /** 4709d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4710d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4711d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4712d60874cdSMiklos Szeredi * 4713d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4714d60874cdSMiklos Szeredi * 4715d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4716d60874cdSMiklos Szeredi * 4717d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4718d60874cdSMiklos Szeredi */ 4719d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4720d60874cdSMiklos Szeredi { 4721d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4722d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4723d60874cdSMiklos Szeredi 4724d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4725d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4726d60874cdSMiklos Szeredi if (!res) 4727d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4728d60874cdSMiklos Szeredi } 4729d60874cdSMiklos Szeredi return res; 4730d60874cdSMiklos Szeredi } 4731d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4732d60874cdSMiklos Szeredi 47331da177e4SLinus Torvalds /* get the link contents into pagecache */ 47346b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4735fceef393SAl Viro struct delayed_call *callback) 47361da177e4SLinus Torvalds { 4737ebd09abbSDuane Griffin char *kaddr; 47381da177e4SLinus Torvalds struct page *page; 47396b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47406b255391SAl Viro 4741d3883d4fSAl Viro if (!dentry) { 4742d3883d4fSAl Viro page = find_get_page(mapping, 0); 4743d3883d4fSAl Viro if (!page) 47446b255391SAl Viro return ERR_PTR(-ECHILD); 4745d3883d4fSAl Viro if (!PageUptodate(page)) { 4746d3883d4fSAl Viro put_page(page); 4747d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4748d3883d4fSAl Viro } 4749d3883d4fSAl Viro } else { 4750090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47511da177e4SLinus Torvalds if (IS_ERR(page)) 47526fe6900eSNick Piggin return (char*)page; 4753d3883d4fSAl Viro } 4754fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 475521fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 475621fc61c7SAl Viro kaddr = page_address(page); 47576b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4758ebd09abbSDuane Griffin return kaddr; 47591da177e4SLinus Torvalds } 47601da177e4SLinus Torvalds 47616b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47621da177e4SLinus Torvalds 4763fceef393SAl Viro void page_put_link(void *arg) 47641da177e4SLinus Torvalds { 4765fceef393SAl Viro put_page(arg); 47661da177e4SLinus Torvalds } 47674d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47681da177e4SLinus Torvalds 4769aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4770aa80deabSAl Viro { 4771fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47726b255391SAl Viro int res = readlink_copy(buffer, buflen, 47736b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4774fceef393SAl Viro &done)); 4775fceef393SAl Viro do_delayed_call(&done); 4776aa80deabSAl Viro return res; 4777aa80deabSAl Viro } 4778aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4779aa80deabSAl Viro 478054566b2cSNick Piggin /* 478154566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 478254566b2cSNick Piggin */ 478354566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47841da177e4SLinus Torvalds { 47851da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47860adb25d2SKirill Korotaev struct page *page; 4787afddba49SNick Piggin void *fsdata; 4788beb497abSDmitriy Monakhov int err; 4789c718a975STetsuo Handa unsigned int flags = 0; 479054566b2cSNick Piggin if (nofs) 479154566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47921da177e4SLinus Torvalds 47937e53cac4SNeilBrown retry: 4794afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 479554566b2cSNick Piggin flags, &page, &fsdata); 47961da177e4SLinus Torvalds if (err) 4797afddba49SNick Piggin goto fail; 4798afddba49SNick Piggin 479921fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4800afddba49SNick Piggin 4801afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4802afddba49SNick Piggin page, fsdata); 48031da177e4SLinus Torvalds if (err < 0) 48041da177e4SLinus Torvalds goto fail; 4805afddba49SNick Piggin if (err < len-1) 4806afddba49SNick Piggin goto retry; 4807afddba49SNick Piggin 48081da177e4SLinus Torvalds mark_inode_dirty(inode); 48091da177e4SLinus Torvalds return 0; 48101da177e4SLinus Torvalds fail: 48111da177e4SLinus Torvalds return err; 48121da177e4SLinus Torvalds } 48134d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48141da177e4SLinus Torvalds 48150adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48160adb25d2SKirill Korotaev { 48170adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4818c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48190adb25d2SKirill Korotaev } 48204d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48210adb25d2SKirill Korotaev 482292e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48236b255391SAl Viro .get_link = page_get_link, 48241da177e4SLinus Torvalds }; 48251da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4826