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 | 11135d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11145d38f049SIan Kent path->dentry->d_inode) 11159875cf80SDavid Howells return -EISDIR; 11160ec26fd0SMiklos Szeredi 1117756daf26SNeilBrown nd->total_link_count++; 1118756daf26SNeilBrown if (nd->total_link_count >= 40) 11199875cf80SDavid Howells return -ELOOP; 11209875cf80SDavid Howells 11219875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11229875cf80SDavid Howells if (IS_ERR(mnt)) { 11239875cf80SDavid Howells /* 11249875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11259875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11269875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11279875cf80SDavid Howells * 11289875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11299875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11309875cf80SDavid Howells * the path is inaccessible and we should say so. 11319875cf80SDavid Howells */ 1132756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11339875cf80SDavid Howells return -EREMOTE; 11349875cf80SDavid Howells return PTR_ERR(mnt); 113531e6b01fSNick Piggin } 1136ea5b778aSDavid Howells 11379875cf80SDavid Howells if (!mnt) /* mount collision */ 11389875cf80SDavid Howells return 0; 11399875cf80SDavid Howells 11408aef1884SAl Viro if (!*need_mntput) { 11418aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11428aef1884SAl Viro mntget(path->mnt); 11438aef1884SAl Viro *need_mntput = true; 11448aef1884SAl Viro } 114519a167afSAl Viro err = finish_automount(mnt, path); 1146ea5b778aSDavid Howells 1147ea5b778aSDavid Howells switch (err) { 1148ea5b778aSDavid Howells case -EBUSY: 1149ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 115019a167afSAl Viro return 0; 1151ea5b778aSDavid Howells case 0: 11528aef1884SAl Viro path_put(path); 11539875cf80SDavid Howells path->mnt = mnt; 11549875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11559875cf80SDavid Howells return 0; 115619a167afSAl Viro default: 115719a167afSAl Viro return err; 11589875cf80SDavid Howells } 115919a167afSAl Viro 1160ea5b778aSDavid Howells } 11619875cf80SDavid Howells 11629875cf80SDavid Howells /* 11639875cf80SDavid Howells * Handle a dentry that is managed in some way. 1164cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11659875cf80SDavid Howells * - Flagged as mountpoint 11669875cf80SDavid Howells * - Flagged as automount point 11679875cf80SDavid Howells * 11689875cf80SDavid Howells * This may only be called in refwalk mode. 11699875cf80SDavid Howells * 11709875cf80SDavid Howells * Serialization is taken care of in namespace.c 11719875cf80SDavid Howells */ 1172756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11739875cf80SDavid Howells { 11748aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11759875cf80SDavid Howells unsigned managed; 11769875cf80SDavid Howells bool need_mntput = false; 11778aef1884SAl Viro int ret = 0; 11789875cf80SDavid Howells 11799875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11809875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11819875cf80SDavid Howells * the components of that value change under us */ 11826aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 11839875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11849875cf80SDavid Howells unlikely(managed != 0)) { 1185cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1186cc53ce53SDavid Howells * being held. */ 1187cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1188cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1189cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1190fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1191cc53ce53SDavid Howells if (ret < 0) 11928aef1884SAl Viro break; 1193cc53ce53SDavid Howells } 1194cc53ce53SDavid Howells 11959875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11969875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11979875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11989875cf80SDavid Howells if (mounted) { 11999875cf80SDavid Howells dput(path->dentry); 12009875cf80SDavid Howells if (need_mntput) 1201463ffb2eSAl Viro mntput(path->mnt); 1202463ffb2eSAl Viro path->mnt = mounted; 1203463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12049875cf80SDavid Howells need_mntput = true; 12059875cf80SDavid Howells continue; 1206463ffb2eSAl Viro } 1207463ffb2eSAl Viro 12089875cf80SDavid Howells /* Something is mounted on this dentry in another 12099875cf80SDavid Howells * namespace and/or whatever was mounted there in this 121048a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 121148a066e7SAl Viro * get it */ 12121da177e4SLinus Torvalds } 12139875cf80SDavid Howells 12149875cf80SDavid Howells /* Handle an automount point */ 12159875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1216756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12179875cf80SDavid Howells if (ret < 0) 12188aef1884SAl Viro break; 12199875cf80SDavid Howells continue; 12209875cf80SDavid Howells } 12219875cf80SDavid Howells 12229875cf80SDavid Howells /* We didn't change the current path point */ 12239875cf80SDavid Howells break; 12249875cf80SDavid Howells } 12258aef1884SAl Viro 12268aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12278aef1884SAl Viro mntput(path->mnt); 1228e9742b53SAl Viro if (ret == -EISDIR || !ret) 1229e9742b53SAl Viro ret = 1; 12308402752eSAl Viro if (need_mntput) 12318402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12328402752eSAl Viro if (unlikely(ret < 0)) 12338402752eSAl Viro path_put_conditional(path, nd); 12348402752eSAl Viro return ret; 12351da177e4SLinus Torvalds } 12361da177e4SLinus Torvalds 1237cc53ce53SDavid Howells int follow_down_one(struct path *path) 12381da177e4SLinus Torvalds { 12391da177e4SLinus Torvalds struct vfsmount *mounted; 12401da177e4SLinus Torvalds 12411c755af4SAl Viro mounted = lookup_mnt(path); 12421da177e4SLinus Torvalds if (mounted) { 12439393bd07SAl Viro dput(path->dentry); 12449393bd07SAl Viro mntput(path->mnt); 12459393bd07SAl Viro path->mnt = mounted; 12469393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12471da177e4SLinus Torvalds return 1; 12481da177e4SLinus Torvalds } 12491da177e4SLinus Torvalds return 0; 12501da177e4SLinus Torvalds } 12514d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12521da177e4SLinus Torvalds 1253fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 125462a7375eSIan Kent { 1255fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1256fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 125762a7375eSIan Kent } 125862a7375eSIan Kent 12599875cf80SDavid Howells /* 1260287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1261287548e4SAl Viro * we meet a managed dentry that would need blocking. 12629875cf80SDavid Howells */ 12639875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1264254cf582SAl Viro struct inode **inode, unsigned *seqp) 12659875cf80SDavid Howells { 126662a7375eSIan Kent for (;;) { 1267c7105365SAl Viro struct mount *mounted; 126862a7375eSIan Kent /* 126962a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 127062a7375eSIan Kent * that wants to block transit. 127162a7375eSIan Kent */ 1272fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1273b8faf035SNeilBrown case -ECHILD: 1274b8faf035SNeilBrown default: 1275ab90911fSDavid Howells return false; 1276b8faf035SNeilBrown case -EISDIR: 1277b8faf035SNeilBrown return true; 1278b8faf035SNeilBrown case 0: 1279b8faf035SNeilBrown break; 1280b8faf035SNeilBrown } 128162a7375eSIan Kent 128262a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1283b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 128462a7375eSIan Kent 1285474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12869875cf80SDavid Howells if (!mounted) 12879875cf80SDavid Howells break; 1288c7105365SAl Viro path->mnt = &mounted->mnt; 1289c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1290a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1291254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 129259430262SLinus Torvalds /* 129359430262SLinus Torvalds * Update the inode too. We don't need to re-check the 129459430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129559430262SLinus Torvalds * because a mount-point is always pinned. 129659430262SLinus Torvalds */ 129759430262SLinus Torvalds *inode = path->dentry->d_inode; 12989875cf80SDavid Howells } 1299f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1300b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1301287548e4SAl Viro } 1302287548e4SAl Viro 130331e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 130431e6b01fSNick Piggin { 13054023bfc9SAl Viro struct inode *inode = nd->inode; 130631e6b01fSNick Piggin 130731e6b01fSNick Piggin while (1) { 1308aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 130931e6b01fSNick Piggin break; 131031e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 131131e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 131231e6b01fSNick Piggin struct dentry *parent = old->d_parent; 131331e6b01fSNick Piggin unsigned seq; 131431e6b01fSNick Piggin 13154023bfc9SAl Viro inode = parent->d_inode; 131631e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1317aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1318aed434adSAl Viro return -ECHILD; 131931e6b01fSNick Piggin nd->path.dentry = parent; 132031e6b01fSNick Piggin nd->seq = seq; 1321397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1322397d425dSEric W. Biederman return -ENOENT; 132331e6b01fSNick Piggin break; 1324aed434adSAl Viro } else { 1325aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1326aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1327aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1328aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1329aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1330aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1331aed434adSAl Viro return -ECHILD; 1332aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 133331e6b01fSNick Piggin break; 1334aed434adSAl Viro /* we know that mountpoint was pinned */ 1335aed434adSAl Viro nd->path.dentry = mountpoint; 1336aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1337aed434adSAl Viro inode = inode2; 1338aed434adSAl Viro nd->seq = seq; 133931e6b01fSNick Piggin } 1340aed434adSAl Viro } 1341aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1342b37199e6SAl Viro struct mount *mounted; 1343b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1344aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1345aed434adSAl Viro return -ECHILD; 1346b37199e6SAl Viro if (!mounted) 1347b37199e6SAl Viro break; 1348b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1349b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13504023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1351b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1352b37199e6SAl Viro } 13534023bfc9SAl Viro nd->inode = inode; 135431e6b01fSNick Piggin return 0; 135531e6b01fSNick Piggin } 135631e6b01fSNick Piggin 13579875cf80SDavid Howells /* 1358cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1359cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1360cc53ce53SDavid Howells * caller is permitted to proceed or not. 1361cc53ce53SDavid Howells */ 13627cc90cc3SAl Viro int follow_down(struct path *path) 1363cc53ce53SDavid Howells { 1364cc53ce53SDavid Howells unsigned managed; 1365cc53ce53SDavid Howells int ret; 1366cc53ce53SDavid Howells 13676aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1368cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1369cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1370cc53ce53SDavid Howells * being held. 1371cc53ce53SDavid Howells * 1372cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1373cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1374cc53ce53SDavid Howells * other than its daemon the right to mount on its 1375cc53ce53SDavid Howells * superstructure. 1376cc53ce53SDavid Howells * 1377cc53ce53SDavid Howells * The filesystem may sleep at this point. 1378cc53ce53SDavid Howells */ 1379cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1380cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1381cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1382fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1383cc53ce53SDavid Howells if (ret < 0) 1384cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1385cc53ce53SDavid Howells } 1386cc53ce53SDavid Howells 1387cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1388cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1389cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1390cc53ce53SDavid Howells if (!mounted) 1391cc53ce53SDavid Howells break; 1392cc53ce53SDavid Howells dput(path->dentry); 1393cc53ce53SDavid Howells mntput(path->mnt); 1394cc53ce53SDavid Howells path->mnt = mounted; 1395cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1396cc53ce53SDavid Howells continue; 1397cc53ce53SDavid Howells } 1398cc53ce53SDavid Howells 1399cc53ce53SDavid Howells /* Don't handle automount points here */ 1400cc53ce53SDavid Howells break; 1401cc53ce53SDavid Howells } 1402cc53ce53SDavid Howells return 0; 1403cc53ce53SDavid Howells } 14044d359507SAl Viro EXPORT_SYMBOL(follow_down); 1405cc53ce53SDavid Howells 1406cc53ce53SDavid Howells /* 14079875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14089875cf80SDavid Howells */ 14099875cf80SDavid Howells static void follow_mount(struct path *path) 14109875cf80SDavid Howells { 14119875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14129875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14139875cf80SDavid Howells if (!mounted) 14149875cf80SDavid Howells break; 14159875cf80SDavid Howells dput(path->dentry); 14169875cf80SDavid Howells mntput(path->mnt); 14179875cf80SDavid Howells path->mnt = mounted; 14189875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14199875cf80SDavid Howells } 14209875cf80SDavid Howells } 14219875cf80SDavid Howells 1422eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1423eedf265aSEric W. Biederman { 1424eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1425eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1426eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1427eedf265aSEric W. Biederman dput(old); 1428eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1429eedf265aSEric W. Biederman return -ENOENT; 1430eedf265aSEric W. Biederman return 0; 1431eedf265aSEric W. Biederman } 1432eedf265aSEric W. Biederman 1433397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14341da177e4SLinus Torvalds { 14351da177e4SLinus Torvalds while(1) { 14362a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14372a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14381da177e4SLinus Torvalds break; 14391da177e4SLinus Torvalds } 14404ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1441eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1442eedf265aSEric W. Biederman if (ret) 1443eedf265aSEric W. Biederman return ret; 14441da177e4SLinus Torvalds break; 14451da177e4SLinus Torvalds } 14463088dd70SAl Viro if (!follow_up(&nd->path)) 14471da177e4SLinus Torvalds break; 14481da177e4SLinus Torvalds } 144979ed0226SAl Viro follow_mount(&nd->path); 145031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1451397d425dSEric W. Biederman return 0; 14521da177e4SLinus Torvalds } 14531da177e4SLinus Torvalds 14541da177e4SLinus Torvalds /* 1455f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1456f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1457baa03890SNick Piggin */ 1458e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1459e3c13928SAl Viro struct dentry *dir, 14606c51e513SAl Viro unsigned int flags) 1461baa03890SNick Piggin { 1462a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1463bad61189SMiklos Szeredi if (dentry) { 1464a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1465bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146674ff0ffcSAl Viro if (!error) 14675542aa2fSEric W. Biederman d_invalidate(dentry); 1468bad61189SMiklos Szeredi dput(dentry); 146974ff0ffcSAl Viro return ERR_PTR(error); 1470bad61189SMiklos Szeredi } 1471bad61189SMiklos Szeredi } 1472baa03890SNick Piggin return dentry; 1473baa03890SNick Piggin } 1474baa03890SNick Piggin 1475baa03890SNick Piggin /* 1476a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1477a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1478a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1479a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1480a03ece5fSAl Viro * at all. 148144396f4bSJosef Bacik */ 1482a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1483a03ece5fSAl Viro struct dentry *base, unsigned int flags) 148444396f4bSJosef Bacik { 1485a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 148644396f4bSJosef Bacik struct dentry *old; 1487a03ece5fSAl Viro struct inode *dir = base->d_inode; 1488a03ece5fSAl Viro 1489a03ece5fSAl Viro if (dentry) 1490a03ece5fSAl Viro return dentry; 149144396f4bSJosef Bacik 149244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1493a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 149444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1495a03ece5fSAl Viro 1496a03ece5fSAl Viro dentry = d_alloc(base, name); 1497a03ece5fSAl Viro if (unlikely(!dentry)) 1498a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 149944396f4bSJosef Bacik 150072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 150144396f4bSJosef Bacik if (unlikely(old)) { 150244396f4bSJosef Bacik dput(dentry); 150344396f4bSJosef Bacik dentry = old; 150444396f4bSJosef Bacik } 150544396f4bSJosef Bacik return dentry; 150644396f4bSJosef Bacik } 150744396f4bSJosef Bacik 1508e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1509254cf582SAl Viro struct path *path, struct inode **inode, 1510254cf582SAl Viro unsigned *seqp) 15111da177e4SLinus Torvalds { 15124ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151331e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15145a18fff2SAl Viro int status = 1; 15159875cf80SDavid Howells int err; 15169875cf80SDavid Howells 15173cac260aSAl Viro /* 1518b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15195d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15205d0f49c1SAl Viro * going to fall back to non-racy lookup. 1521b04f784eSNick Piggin */ 152231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152331e6b01fSNick Piggin unsigned seq; 1524766c4cbfSAl Viro bool negative; 1525da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15265d0f49c1SAl Viro if (unlikely(!dentry)) { 15274675ac39SAl Viro if (unlazy_walk(nd)) 15285d0f49c1SAl Viro return -ECHILD; 1529e9742b53SAl Viro return 0; 15305d0f49c1SAl Viro } 15315a18fff2SAl Viro 153212f8ad4bSLinus Torvalds /* 153312f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153412f8ad4bSLinus Torvalds * the dentry name information from lookup. 153512f8ad4bSLinus Torvalds */ 153663afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1537766c4cbfSAl Viro negative = d_is_negative(dentry); 15385d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 153912f8ad4bSLinus Torvalds return -ECHILD; 154012f8ad4bSLinus Torvalds 154112f8ad4bSLinus Torvalds /* 154212f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154312f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154412f8ad4bSLinus Torvalds * 154512f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 154612f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 154712f8ad4bSLinus Torvalds */ 15485d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 154931e6b01fSNick Piggin return -ECHILD; 15505a18fff2SAl Viro 1551254cf582SAl Viro *seqp = seq; 15524ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1553209a7fb2SAl Viro if (likely(status > 0)) { 1554daf3761cSTrond Myklebust /* 1555daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1556daf3761cSTrond Myklebust * case that drops it. 1557daf3761cSTrond Myklebust */ 15585d0f49c1SAl Viro if (unlikely(negative)) 1559daf3761cSTrond Myklebust return -ENOENT; 156031e6b01fSNick Piggin path->mnt = mnt; 156131e6b01fSNick Piggin path->dentry = dentry; 1562254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1563e9742b53SAl Viro return 1; 15645d0f49c1SAl Viro } 15654675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1566254cf582SAl Viro return -ECHILD; 1567209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1568209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1569209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15705a18fff2SAl Viro } else { 1571e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157281e6f520SAl Viro if (unlikely(!dentry)) 1573e9742b53SAl Viro return 0; 15744ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15755d0f49c1SAl Viro } 15765a18fff2SAl Viro if (unlikely(status <= 0)) { 1577e9742b53SAl Viro if (!status) 15785d0f49c1SAl Viro d_invalidate(dentry); 15795a18fff2SAl Viro dput(dentry); 15805a18fff2SAl Viro return status; 15815a18fff2SAl Viro } 1582766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1583766c4cbfSAl Viro dput(dentry); 1584766c4cbfSAl Viro return -ENOENT; 1585766c4cbfSAl Viro } 15865d0f49c1SAl Viro 15871da177e4SLinus Torvalds path->mnt = mnt; 15881da177e4SLinus Torvalds path->dentry = dentry; 1589756daf26SNeilBrown err = follow_managed(path, nd); 1590e9742b53SAl Viro if (likely(err > 0)) 159163afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15928402752eSAl Viro return err; 1593697f514dSMiklos Szeredi } 1594697f514dSMiklos Szeredi 1595697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1596e3c13928SAl Viro static struct dentry *lookup_slow(const struct qstr *name, 1597e3c13928SAl Viro struct dentry *dir, 1598e3c13928SAl Viro unsigned int flags) 1599697f514dSMiklos Szeredi { 160094bdd655SAl Viro struct dentry *dentry = ERR_PTR(-ENOENT), *old; 16011936386eSAl Viro struct inode *inode = dir->d_inode; 1602d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16031936386eSAl Viro 16049902af79SAl Viro inode_lock_shared(inode); 16051936386eSAl Viro /* Don't go there if it's already dead */ 160694bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 160794bdd655SAl Viro goto out; 160894bdd655SAl Viro again: 1609d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 161094bdd655SAl Viro if (IS_ERR(dentry)) 161194bdd655SAl Viro goto out; 161294bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1613a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1614949a852eSAl Viro int error = d_revalidate(dentry, flags); 1615949a852eSAl Viro if (unlikely(error <= 0)) { 161694bdd655SAl Viro if (!error) { 1617949a852eSAl Viro d_invalidate(dentry); 1618949a852eSAl Viro dput(dentry); 161994bdd655SAl Viro goto again; 162094bdd655SAl Viro } 162194bdd655SAl Viro dput(dentry); 1622949a852eSAl Viro dentry = ERR_PTR(error); 1623949a852eSAl Viro } 1624949a852eSAl Viro } 162594bdd655SAl Viro } else { 16261936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 162785c7f810SAl Viro d_lookup_done(dentry); 16281936386eSAl Viro if (unlikely(old)) { 16291936386eSAl Viro dput(dentry); 16301936386eSAl Viro dentry = old; 1631949a852eSAl Viro } 1632949a852eSAl Viro } 163394bdd655SAl Viro out: 16349902af79SAl Viro inode_unlock_shared(inode); 1635e3c13928SAl Viro return dentry; 16361da177e4SLinus Torvalds } 16371da177e4SLinus Torvalds 163852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 163952094c8aSAl Viro { 164052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16414ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164252094c8aSAl Viro if (err != -ECHILD) 164352094c8aSAl Viro return err; 16444675ac39SAl Viro if (unlazy_walk(nd)) 164552094c8aSAl Viro return -ECHILD; 164652094c8aSAl Viro } 16474ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 164852094c8aSAl Viro } 164952094c8aSAl Viro 16509856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16519856fa1bSAl Viro { 16529856fa1bSAl Viro if (type == LAST_DOTDOT) { 16539e6697e2SAl Viro if (!nd->root.mnt) 16549e6697e2SAl Viro set_root(nd); 16559856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 165670291aecSAl Viro return follow_dotdot_rcu(nd); 16579856fa1bSAl Viro } else 1658397d425dSEric W. Biederman return follow_dotdot(nd); 16599856fa1bSAl Viro } 16609856fa1bSAl Viro return 0; 16619856fa1bSAl Viro } 16629856fa1bSAl Viro 1663181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1664181548c0SAl Viro struct inode *inode, unsigned seq) 1665d63ff28fSAl Viro { 1666626de996SAl Viro int error; 16671cf2665bSAl Viro struct saved *last; 1668756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1669626de996SAl Viro path_to_nameidata(link, nd); 1670626de996SAl Viro return -ELOOP; 1671626de996SAl Viro } 1672bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1673cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1674cd179f44SAl Viro mntget(link->mnt); 16757973387aSAl Viro } 1676626de996SAl Viro error = nd_alloc_stack(nd); 1677626de996SAl Viro if (unlikely(error)) { 1678bc40aee0SAl Viro if (error == -ECHILD) { 1679ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1680ad1633a1SAl Viro drop_links(nd); 1681ad1633a1SAl Viro nd->depth = 0; 1682ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1683ad1633a1SAl Viro nd->path.mnt = NULL; 1684ad1633a1SAl Viro nd->path.dentry = NULL; 1685ad1633a1SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1686ad1633a1SAl Viro nd->root.mnt = NULL; 1687ad1633a1SAl Viro rcu_read_unlock(); 16884675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1689bc40aee0SAl Viro error = nd_alloc_stack(nd); 1690bc40aee0SAl Viro } 1691bc40aee0SAl Viro if (error) { 1692cd179f44SAl Viro path_put(link); 1693626de996SAl Viro return error; 1694626de996SAl Viro } 1695bc40aee0SAl Viro } 1696626de996SAl Viro 1697ab104923SAl Viro last = nd->stack + nd->depth++; 16981cf2665bSAl Viro last->link = *link; 1699fceef393SAl Viro clear_delayed_call(&last->done); 1700fceef393SAl Viro nd->link_inode = inode; 17010450b2d1SAl Viro last->seq = seq; 1702d63ff28fSAl Viro return 1; 1703d63ff28fSAl Viro } 1704d63ff28fSAl Viro 17058f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 170631d66bcdSAl Viro 17073ddcd056SLinus Torvalds /* 17083ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17093ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17103ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17113ddcd056SLinus Torvalds * for the common case. 17123ddcd056SLinus Torvalds */ 17138f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17148f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17153ddcd056SLinus Torvalds { 171631d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 171731d66bcdSAl Viro put_link(nd); 17188f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17198f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17208f64fb1cSAl Viro /* not a symlink or should not follow */ 17218f64fb1cSAl Viro path_to_nameidata(path, nd); 17228f64fb1cSAl Viro nd->inode = inode; 17238f64fb1cSAl Viro nd->seq = seq; 1724d63ff28fSAl Viro return 0; 17258f64fb1cSAl Viro } 1726a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1727a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17288f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1729a7f77542SAl Viro return -ECHILD; 1730a7f77542SAl Viro } 17318f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17323ddcd056SLinus Torvalds } 17333ddcd056SLinus Torvalds 17344693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1735ce57dfc1SAl Viro { 1736caa85634SAl Viro struct path path; 1737ce57dfc1SAl Viro struct inode *inode; 1738254cf582SAl Viro unsigned seq; 1739ce57dfc1SAl Viro int err; 1740ce57dfc1SAl Viro /* 1741ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1742ce57dfc1SAl Viro * to be able to know about the current root directory and 1743ce57dfc1SAl Viro * parent relationships. 1744ce57dfc1SAl Viro */ 17454693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17464693a547SAl Viro err = handle_dots(nd, nd->last_type); 17471c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17484693a547SAl Viro put_link(nd); 17494693a547SAl Viro return err; 17504693a547SAl Viro } 1751254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1752e9742b53SAl Viro if (unlikely(err <= 0)) { 1753697f514dSMiklos Szeredi if (err < 0) 1754f0a9ba70SAl Viro return err; 1755e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1756e3c13928SAl Viro nd->flags); 1757e3c13928SAl Viro if (IS_ERR(path.dentry)) 1758e3c13928SAl Viro return PTR_ERR(path.dentry); 17597500c38aSAl Viro 1760e3c13928SAl Viro path.mnt = nd->path.mnt; 1761e3c13928SAl Viro err = follow_managed(&path, nd); 1762e3c13928SAl Viro if (unlikely(err < 0)) 1763f0a9ba70SAl Viro return err; 1764697f514dSMiklos Szeredi 17657500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17667500c38aSAl Viro path_to_nameidata(&path, nd); 17677500c38aSAl Viro return -ENOENT; 17687500c38aSAl Viro } 17697500c38aSAl Viro 1770254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1771d4565649SAl Viro inode = d_backing_inode(path.dentry); 1772766c4cbfSAl Viro } 1773697f514dSMiklos Szeredi 17748f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1775ce57dfc1SAl Viro } 1776ce57dfc1SAl Viro 17771da177e4SLinus Torvalds /* 1778bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1779bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1780bfcfaa77SLinus Torvalds * 1781bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1782bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1783bfcfaa77SLinus Torvalds * fast. 1784bfcfaa77SLinus Torvalds * 1785bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1786bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1787bfcfaa77SLinus Torvalds * crossing operation. 1788bfcfaa77SLinus Torvalds * 1789bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1790bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1791bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1792bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1793bfcfaa77SLinus Torvalds */ 1794bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1795bfcfaa77SLinus Torvalds 1796f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1797bfcfaa77SLinus Torvalds 1798468a9428SGeorge Spelvin #ifdef HASH_MIX 1799bfcfaa77SLinus Torvalds 1800468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1801468a9428SGeorge Spelvin 1802468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18032a18da7aSGeorge Spelvin /* 18042a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18052a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18062a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18072a18da7aSGeorge Spelvin * and no temporaries. 18082a18da7aSGeorge Spelvin * 18092a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18102a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18112a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18122a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18132a18da7aSGeorge Spelvin * 18142a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18152a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18162a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18172a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18182a18da7aSGeorge Spelvin * 18192a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18202a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18212a18da7aSGeorge Spelvin * toggling any given output bit. 18222a18da7aSGeorge Spelvin * 18232a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18242a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18252a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18262a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18272a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18282a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18292a18da7aSGeorge Spelvin * Perfect: 8192 258048 18302a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18312a18da7aSGeorge Spelvin */ 18322a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18332a18da7aSGeorge Spelvin ( x ^= (a), \ 18342a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18352a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18362a18da7aSGeorge Spelvin y *= 9 ) 1837bfcfaa77SLinus Torvalds 18380fed3ac8SGeorge Spelvin /* 18392a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18402a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18412a18da7aSGeorge Spelvin * work done before the hash value is used. 18420fed3ac8SGeorge Spelvin */ 18432a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18440fed3ac8SGeorge Spelvin { 18452a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18462a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18472a18da7aSGeorge Spelvin return y >> 32; 18480fed3ac8SGeorge Spelvin } 18490fed3ac8SGeorge Spelvin 1850bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1851bfcfaa77SLinus Torvalds 18522a18da7aSGeorge Spelvin /* 18532a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18542a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18552a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18562a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18572a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18582a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18592a18da7aSGeorge Spelvin * Perfect: 2048 31744 18602a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18612a18da7aSGeorge Spelvin */ 18622a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18632a18da7aSGeorge Spelvin ( x ^= (a), \ 18642a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18652a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18662a18da7aSGeorge Spelvin y *= 9 ) 1867bfcfaa77SLinus Torvalds 18682a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18690fed3ac8SGeorge Spelvin { 18702a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18712a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18720fed3ac8SGeorge Spelvin } 18730fed3ac8SGeorge Spelvin 1874bfcfaa77SLinus Torvalds #endif 1875bfcfaa77SLinus Torvalds 18762a18da7aSGeorge Spelvin /* 18772a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18782a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18792a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18802a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18812a18da7aSGeorge Spelvin * finds the delimiter after the name. 18822a18da7aSGeorge Spelvin */ 18838387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1884bfcfaa77SLinus Torvalds { 18858387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1886bfcfaa77SLinus Torvalds 1887bfcfaa77SLinus Torvalds for (;;) { 1888fcfd2fbfSGeorge Spelvin if (!len) 1889fcfd2fbfSGeorge Spelvin goto done; 1890e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1891bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1892bfcfaa77SLinus Torvalds break; 18932a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1894bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1895bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1896bfcfaa77SLinus Torvalds } 18972a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1898bfcfaa77SLinus Torvalds done: 18992a18da7aSGeorge Spelvin return fold_hash(x, y); 1900bfcfaa77SLinus Torvalds } 1901bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1902bfcfaa77SLinus Torvalds 1903fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19048387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1905fcfd2fbfSGeorge Spelvin { 19068387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19078387ff25SLinus Torvalds unsigned long adata, mask, len; 1908fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1909fcfd2fbfSGeorge Spelvin 19108387ff25SLinus Torvalds len = 0; 19118387ff25SLinus Torvalds goto inside; 19128387ff25SLinus Torvalds 1913fcfd2fbfSGeorge Spelvin do { 19142a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1915fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19168387ff25SLinus Torvalds inside: 1917fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1918fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1919fcfd2fbfSGeorge Spelvin 1920fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1921fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19222a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1923fcfd2fbfSGeorge Spelvin 19242a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1925fcfd2fbfSGeorge Spelvin } 1926fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1927fcfd2fbfSGeorge Spelvin 1928bfcfaa77SLinus Torvalds /* 1929bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1930d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1931bfcfaa77SLinus Torvalds */ 19328387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1933bfcfaa77SLinus Torvalds { 19348387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19358387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 193636126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1937bfcfaa77SLinus Torvalds 19388387ff25SLinus Torvalds len = 0; 19398387ff25SLinus Torvalds goto inside; 19408387ff25SLinus Torvalds 1941bfcfaa77SLinus Torvalds do { 19422a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1943bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19448387ff25SLinus Torvalds inside: 1945e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 194636126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 194736126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1948bfcfaa77SLinus Torvalds 194936126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 195036126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 195136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19522a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 195336126f8fSLinus Torvalds 19542a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1955bfcfaa77SLinus Torvalds } 1956bfcfaa77SLinus Torvalds 19572a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1958bfcfaa77SLinus Torvalds 1959fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19608387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19610145acc2SLinus Torvalds { 19628387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 19630145acc2SLinus Torvalds while (len--) 1964fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19650145acc2SLinus Torvalds return end_name_hash(hash); 19660145acc2SLinus Torvalds } 1967ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19680145acc2SLinus Torvalds 1969fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19708387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1971fcfd2fbfSGeorge Spelvin { 19728387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1973fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1974fcfd2fbfSGeorge Spelvin 1975fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1976e0ab7af9SGeorge Spelvin while (c) { 1977fcfd2fbfSGeorge Spelvin len++; 1978fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1979fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1980e0ab7af9SGeorge Spelvin } 1981fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1982fcfd2fbfSGeorge Spelvin } 1983f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1984fcfd2fbfSGeorge Spelvin 19853ddcd056SLinus Torvalds /* 1986200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1987200e9ef7SLinus Torvalds * one character. 1988200e9ef7SLinus Torvalds */ 19898387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1990200e9ef7SLinus Torvalds { 19918387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1992200e9ef7SLinus Torvalds unsigned long len = 0, c; 1993200e9ef7SLinus Torvalds 1994200e9ef7SLinus Torvalds c = (unsigned char)*name; 1995200e9ef7SLinus Torvalds do { 1996200e9ef7SLinus Torvalds len++; 1997200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1998200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1999200e9ef7SLinus Torvalds } while (c && c != '/'); 2000d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2001200e9ef7SLinus Torvalds } 2002200e9ef7SLinus Torvalds 2003bfcfaa77SLinus Torvalds #endif 2004bfcfaa77SLinus Torvalds 2005200e9ef7SLinus Torvalds /* 20061da177e4SLinus Torvalds * Name resolution. 2007ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2008ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20091da177e4SLinus Torvalds * 2010ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2011ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20121da177e4SLinus Torvalds */ 20136de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20141da177e4SLinus Torvalds { 20151da177e4SLinus Torvalds int err; 20161da177e4SLinus Torvalds 20171da177e4SLinus Torvalds while (*name=='/') 20181da177e4SLinus Torvalds name++; 20191da177e4SLinus Torvalds if (!*name) 20209e18f10aSAl Viro return 0; 20211da177e4SLinus Torvalds 20221da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20231da177e4SLinus Torvalds for(;;) { 2024d6bb3e90SLinus Torvalds u64 hash_len; 2025fe479a58SAl Viro int type; 20261da177e4SLinus Torvalds 202752094c8aSAl Viro err = may_lookup(nd); 20281da177e4SLinus Torvalds if (err) 20293595e234SAl Viro return err; 20301da177e4SLinus Torvalds 20318387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20321da177e4SLinus Torvalds 2033fe479a58SAl Viro type = LAST_NORM; 2034d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2035fe479a58SAl Viro case 2: 2036200e9ef7SLinus Torvalds if (name[1] == '.') { 2037fe479a58SAl Viro type = LAST_DOTDOT; 203816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 203916c2cd71SAl Viro } 2040fe479a58SAl Viro break; 2041fe479a58SAl Viro case 1: 2042fe479a58SAl Viro type = LAST_DOT; 2043fe479a58SAl Viro } 20445a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20455a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 204616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20475a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2048a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2049da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20505a202bcdSAl Viro if (err < 0) 20513595e234SAl Viro return err; 2052d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2053d6bb3e90SLinus Torvalds name = this.name; 20545a202bcdSAl Viro } 20555a202bcdSAl Viro } 2056fe479a58SAl Viro 2057d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2058d6bb3e90SLinus Torvalds nd->last.name = name; 20595f4a6a69SAl Viro nd->last_type = type; 20605f4a6a69SAl Viro 2061d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2062d6bb3e90SLinus Torvalds if (!*name) 2063bdf6cbf1SAl Viro goto OK; 2064200e9ef7SLinus Torvalds /* 2065200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2066200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2067200e9ef7SLinus Torvalds */ 2068200e9ef7SLinus Torvalds do { 2069d6bb3e90SLinus Torvalds name++; 2070d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20718620c238SAl Viro if (unlikely(!*name)) { 20728620c238SAl Viro OK: 2073368ee9baSAl Viro /* pathname body, done */ 20748620c238SAl Viro if (!nd->depth) 20758620c238SAl Viro return 0; 20768620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2077368ee9baSAl Viro /* trailing symlink, done */ 20788620c238SAl Viro if (!name) 20798620c238SAl Viro return 0; 20808620c238SAl Viro /* last component of nested symlink */ 20818f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 20821c4ff1a8SAl Viro } else { 20831c4ff1a8SAl Viro /* not the last component */ 20848f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 20858620c238SAl Viro } 2086ce57dfc1SAl Viro if (err < 0) 20873595e234SAl Viro return err; 2088fe479a58SAl Viro 2089ce57dfc1SAl Viro if (err) { 2090626de996SAl Viro const char *s = get_link(nd); 20915a460275SAl Viro 2092a1c83681SViresh Kumar if (IS_ERR(s)) 20933595e234SAl Viro return PTR_ERR(s); 2094172a39a0SAl Viro err = 0; 209512b09578SAl Viro if (unlikely(!s)) { 209612b09578SAl Viro /* jumped */ 2097b9ff4429SAl Viro put_link(nd); 209812b09578SAl Viro } else { 2099071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 210032cd7468SAl Viro name = s; 21019e18f10aSAl Viro continue; 210248c8b0c5SAl Viro } 210331e6b01fSNick Piggin } 210497242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 210597242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21064675ac39SAl Viro if (unlazy_walk(nd)) 210797242f99SAl Viro return -ECHILD; 210897242f99SAl Viro } 21093595e234SAl Viro return -ENOTDIR; 21105f4a6a69SAl Viro } 2111ce57dfc1SAl Viro } 211297242f99SAl Viro } 21131da177e4SLinus Torvalds 2114c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 211531e6b01fSNick Piggin { 2116c8a53ee5SAl Viro const char *s = nd->name->name; 211731e6b01fSNick Piggin 2118c0eb027eSLinus Torvalds if (!*s) 2119c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2120c0eb027eSLinus Torvalds 212131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2122980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 212331e6b01fSNick Piggin nd->depth = 0; 21245b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2125b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2126b18825a7SDavid Howells struct inode *inode = root->d_inode; 212793893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2128368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21295b6ca027SAl Viro nd->path = nd->root; 21305b6ca027SAl Viro nd->inode = inode; 21315b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21328b61e74fSAl Viro rcu_read_lock(); 21335b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21348f47a016SAl Viro nd->root_seq = nd->seq; 213548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21365b6ca027SAl Viro } else { 21375b6ca027SAl Viro path_get(&nd->path); 21385b6ca027SAl Viro } 2139368ee9baSAl Viro return s; 21405b6ca027SAl Viro } 21415b6ca027SAl Viro 214231e6b01fSNick Piggin nd->root.mnt = NULL; 2143248fb5b9SAl Viro nd->path.mnt = NULL; 2144248fb5b9SAl Viro nd->path.dentry = NULL; 214531e6b01fSNick Piggin 214648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2147fd2f7cb5SAl Viro if (*s == '/') { 21489e6697e2SAl Viro if (flags & LOOKUP_RCU) 21498b61e74fSAl Viro rcu_read_lock(); 2150e41f7d4eSAl Viro set_root(nd); 2151248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2152ef55d917SAl Viro return s; 2153ef55d917SAl Viro nd->root.mnt = NULL; 2154ef55d917SAl Viro rcu_read_unlock(); 2155ef55d917SAl Viro return ERR_PTR(-ECHILD); 2156c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2157e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 215831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2159c28cc364SNick Piggin unsigned seq; 216031e6b01fSNick Piggin 21618b61e74fSAl Viro rcu_read_lock(); 216231e6b01fSNick Piggin 2163c28cc364SNick Piggin do { 2164c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 216531e6b01fSNick Piggin nd->path = fs->pwd; 2166ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2167c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2168c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2169e41f7d4eSAl Viro } else { 2170e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2171ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2172e41f7d4eSAl Viro } 2173ef55d917SAl Viro return s; 217431e6b01fSNick Piggin } else { 2175582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2176c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 217731e6b01fSNick Piggin struct dentry *dentry; 217831e6b01fSNick Piggin 21792903ff01SAl Viro if (!f.file) 2180368ee9baSAl Viro return ERR_PTR(-EBADF); 218131e6b01fSNick Piggin 21822903ff01SAl Viro dentry = f.file->f_path.dentry; 218331e6b01fSNick Piggin 2184fd2f7cb5SAl Viro if (*s) { 218544b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21862903ff01SAl Viro fdput(f); 2187368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2188f52e0c11SAl Viro } 21892903ff01SAl Viro } 21902903ff01SAl Viro 21912903ff01SAl Viro nd->path = f.file->f_path; 2192e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 21938b61e74fSAl Viro rcu_read_lock(); 219434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 219534a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 21965590ff0dSUlrich Drepper } else { 21972903ff01SAl Viro path_get(&nd->path); 219834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 21991da177e4SLinus Torvalds } 220034a26b99SAl Viro fdput(f); 2201368ee9baSAl Viro return s; 2202e41f7d4eSAl Viro } 22039b4a9b14SAl Viro } 22049b4a9b14SAl Viro 22053bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 220695fa25d9SAl Viro { 220795fa25d9SAl Viro const char *s; 2208fec2fa24SAl Viro int error = may_follow_link(nd); 2209deb106c6SAl Viro if (unlikely(error)) 22103bdba28bSAl Viro return ERR_PTR(error); 221195fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2212fab51e8aSAl Viro nd->stack[0].name = NULL; 22133b2e7f75SAl Viro s = get_link(nd); 2214deb106c6SAl Viro return s ? s : ""; 221595fa25d9SAl Viro } 221695fa25d9SAl Viro 2217caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2218bd92d7feSAl Viro { 2219bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2220bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2221bd92d7feSAl Viro 2222bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22231c4ff1a8SAl Viro return walk_component(nd, 0); 2224bd92d7feSAl Viro } 2225bd92d7feSAl Viro 22264f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22274f757f3cSAl Viro { 22284f757f3cSAl Viro struct path path = nd->path; 22294f757f3cSAl Viro struct inode *inode = nd->inode; 22304f757f3cSAl Viro unsigned seq = nd->seq; 22314f757f3cSAl Viro int err; 22324f757f3cSAl Viro 22334f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22344f757f3cSAl Viro /* 22354f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22364f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22374f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22384f757f3cSAl Viro */ 22394f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22404f757f3cSAl Viro return -ECHILD; 22414f757f3cSAl Viro } else { 22424f757f3cSAl Viro dget(path.dentry); 22434f757f3cSAl Viro err = follow_managed(&path, nd); 22444f757f3cSAl Viro if (unlikely(err < 0)) 22454f757f3cSAl Viro return err; 22464f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22474f757f3cSAl Viro seq = 0; 22484f757f3cSAl Viro } 22494f757f3cSAl Viro path_to_nameidata(&path, nd); 22504f757f3cSAl Viro nd->inode = inode; 22514f757f3cSAl Viro nd->seq = seq; 22524f757f3cSAl Viro return 0; 22534f757f3cSAl Viro } 22544f757f3cSAl Viro 22559b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2256c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22579b4a9b14SAl Viro { 2258c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2259bd92d7feSAl Viro int err; 226031e6b01fSNick Piggin 2261368ee9baSAl Viro if (IS_ERR(s)) 2262368ee9baSAl Viro return PTR_ERR(s); 22634f757f3cSAl Viro 22644f757f3cSAl Viro if (unlikely(flags & LOOKUP_DOWN)) { 22654f757f3cSAl Viro err = handle_lookup_down(nd); 22664f757f3cSAl Viro if (unlikely(err < 0)) { 22674f757f3cSAl Viro terminate_walk(nd); 22684f757f3cSAl Viro return err; 22694f757f3cSAl Viro } 22704f757f3cSAl Viro } 22714f757f3cSAl Viro 22723bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22733bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22743bdba28bSAl Viro s = trailing_symlink(nd); 22753bdba28bSAl Viro if (IS_ERR(s)) { 22763bdba28bSAl Viro err = PTR_ERR(s); 22776d7b5aaeSAl Viro break; 2278bd92d7feSAl Viro } 2279bd92d7feSAl Viro } 22809f1fafeeSAl Viro if (!err) 22819f1fafeeSAl Viro err = complete_walk(nd); 2282bd92d7feSAl Viro 2283deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2284deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2285bd23a539SAl Viro err = -ENOTDIR; 2286625b6d10SAl Viro if (!err) { 2287625b6d10SAl Viro *path = nd->path; 2288625b6d10SAl Viro nd->path.mnt = NULL; 2289625b6d10SAl Viro nd->path.dentry = NULL; 2290625b6d10SAl Viro } 2291deb106c6SAl Viro terminate_walk(nd); 2292bd92d7feSAl Viro return err; 229331e6b01fSNick Piggin } 229431e6b01fSNick Piggin 2295625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 22969ad1aaa6SAl Viro struct path *path, struct path *root) 2297873f1eedSJeff Layton { 2298894bc8c4SAl Viro int retval; 22999883d185SAl Viro struct nameidata nd; 2300abc9f5beSAl Viro if (IS_ERR(name)) 2301abc9f5beSAl Viro return PTR_ERR(name); 23029ad1aaa6SAl Viro if (unlikely(root)) { 23039ad1aaa6SAl Viro nd.root = *root; 23049ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23059ad1aaa6SAl Viro } 23069883d185SAl Viro set_nameidata(&nd, dfd, name); 2307c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2308873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2309c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2310873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2311c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2312873f1eedSJeff Layton 2313873f1eedSJeff Layton if (likely(!retval)) 2314625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 23159883d185SAl Viro restore_nameidata(); 2316e4bd1c1aSAl Viro putname(name); 2317873f1eedSJeff Layton return retval; 2318873f1eedSJeff Layton } 2319873f1eedSJeff Layton 23208bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2321c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2322391172c4SAl Viro struct path *parent) 23238bcb77faSAl Viro { 2324c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2325368ee9baSAl Viro int err; 2326368ee9baSAl Viro if (IS_ERR(s)) 2327368ee9baSAl Viro return PTR_ERR(s); 2328368ee9baSAl Viro err = link_path_walk(s, nd); 23298bcb77faSAl Viro if (!err) 23308bcb77faSAl Viro err = complete_walk(nd); 2331391172c4SAl Viro if (!err) { 2332391172c4SAl Viro *parent = nd->path; 2333391172c4SAl Viro nd->path.mnt = NULL; 2334391172c4SAl Viro nd->path.dentry = NULL; 2335391172c4SAl Viro } 2336deb106c6SAl Viro terminate_walk(nd); 23378bcb77faSAl Viro return err; 23388bcb77faSAl Viro } 23398bcb77faSAl Viro 23405c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2341391172c4SAl Viro unsigned int flags, struct path *parent, 2342391172c4SAl Viro struct qstr *last, int *type) 23438bcb77faSAl Viro { 23448bcb77faSAl Viro int retval; 23459883d185SAl Viro struct nameidata nd; 23468bcb77faSAl Viro 23475c31b6ceSAl Viro if (IS_ERR(name)) 23485c31b6ceSAl Viro return name; 23499883d185SAl Viro set_nameidata(&nd, dfd, name); 2350c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23518bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2352c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23538bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2354c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2355391172c4SAl Viro if (likely(!retval)) { 2356391172c4SAl Viro *last = nd.last; 2357391172c4SAl Viro *type = nd.last_type; 2358391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23595c31b6ceSAl Viro } else { 23605c31b6ceSAl Viro putname(name); 23615c31b6ceSAl Viro name = ERR_PTR(retval); 2362391172c4SAl Viro } 23639883d185SAl Viro restore_nameidata(); 23645c31b6ceSAl Viro return name; 23658bcb77faSAl Viro } 23668bcb77faSAl Viro 236779714f72SAl Viro /* does lookup, returns the object with parent locked */ 236879714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23695590ff0dSUlrich Drepper { 23705c31b6ceSAl Viro struct filename *filename; 23715c31b6ceSAl Viro struct dentry *d; 2372391172c4SAl Viro struct qstr last; 2373391172c4SAl Viro int type; 237451689104SPaul Moore 23755c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23765c31b6ceSAl Viro &last, &type); 237751689104SPaul Moore if (IS_ERR(filename)) 237851689104SPaul Moore return ERR_CAST(filename); 23795c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2380391172c4SAl Viro path_put(path); 23815c31b6ceSAl Viro putname(filename); 23825c31b6ceSAl Viro return ERR_PTR(-EINVAL); 238379714f72SAl Viro } 23845955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2385391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 238679714f72SAl Viro if (IS_ERR(d)) { 23875955102cSAl Viro inode_unlock(path->dentry->d_inode); 2388391172c4SAl Viro path_put(path); 238979714f72SAl Viro } 239051689104SPaul Moore putname(filename); 239179714f72SAl Viro return d; 23925590ff0dSUlrich Drepper } 23935590ff0dSUlrich Drepper 2394d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2395d1811465SAl Viro { 2396abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2397abc9f5beSAl Viro flags, path, NULL); 2398d1811465SAl Viro } 23994d359507SAl Viro EXPORT_SYMBOL(kern_path); 2400d1811465SAl Viro 240116f18200SJosef 'Jeff' Sipek /** 240216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 240316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 240416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 240516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 240616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2407e0a01249SAl Viro * @path: pointer to struct path to fill 240816f18200SJosef 'Jeff' Sipek */ 240916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 241016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2411e0a01249SAl Viro struct path *path) 241216f18200SJosef 'Jeff' Sipek { 24139ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24149ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2415abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2416abc9f5beSAl Viro flags , path, &root); 241716f18200SJosef 'Jeff' Sipek } 24184d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 241916f18200SJosef 'Jeff' Sipek 2420eead1911SChristoph Hellwig /** 2421a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2422eead1911SChristoph Hellwig * @name: pathname component to lookup 2423eead1911SChristoph Hellwig * @base: base directory to lookup from 2424eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2425eead1911SChristoph Hellwig * 2426a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24279e7543e9SAl Viro * not be called by generic code. 2428bbddca8eSNeilBrown * 2429bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2430eead1911SChristoph Hellwig */ 2431057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2432057f6c01SJames Morris { 2433057f6c01SJames Morris struct qstr this; 24346a96ba54SAl Viro unsigned int c; 2435cda309deSMiklos Szeredi int err; 2436057f6c01SJames Morris 24375955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24382f9092e1SDavid Woodhouse 24396a96ba54SAl Viro this.name = name; 24406a96ba54SAl Viro this.len = len; 24418387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 24426a96ba54SAl Viro if (!len) 24436a96ba54SAl Viro return ERR_PTR(-EACCES); 24446a96ba54SAl Viro 244521d8a15aSAl Viro if (unlikely(name[0] == '.')) { 244621d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 244721d8a15aSAl Viro return ERR_PTR(-EACCES); 244821d8a15aSAl Viro } 244921d8a15aSAl Viro 24506a96ba54SAl Viro while (len--) { 24516a96ba54SAl Viro c = *(const unsigned char *)name++; 24526a96ba54SAl Viro if (c == '/' || c == '\0') 24536a96ba54SAl Viro return ERR_PTR(-EACCES); 24546a96ba54SAl Viro } 24555a202bcdSAl Viro /* 24565a202bcdSAl Viro * See if the low-level filesystem might want 24575a202bcdSAl Viro * to use its own hash.. 24585a202bcdSAl Viro */ 24595a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2460da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 24615a202bcdSAl Viro if (err < 0) 24625a202bcdSAl Viro return ERR_PTR(err); 24635a202bcdSAl Viro } 2464eead1911SChristoph Hellwig 2465cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2466cda309deSMiklos Szeredi if (err) 2467cda309deSMiklos Szeredi return ERR_PTR(err); 2468cda309deSMiklos Szeredi 246972bd866aSAl Viro return __lookup_hash(&this, base, 0); 2470057f6c01SJames Morris } 24714d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2472057f6c01SJames Morris 2473bbddca8eSNeilBrown /** 2474bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2475bbddca8eSNeilBrown * @name: pathname component to lookup 2476bbddca8eSNeilBrown * @base: base directory to lookup from 2477bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2478bbddca8eSNeilBrown * 2479bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2480bbddca8eSNeilBrown * not be called by generic code. 2481bbddca8eSNeilBrown * 2482bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2483bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2484bbddca8eSNeilBrown */ 2485bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2486bbddca8eSNeilBrown struct dentry *base, int len) 2487bbddca8eSNeilBrown { 2488bbddca8eSNeilBrown struct qstr this; 2489bbddca8eSNeilBrown unsigned int c; 2490bbddca8eSNeilBrown int err; 249120d00ee8SLinus Torvalds struct dentry *ret; 2492bbddca8eSNeilBrown 2493bbddca8eSNeilBrown this.name = name; 2494bbddca8eSNeilBrown this.len = len; 24958387ff25SLinus Torvalds this.hash = full_name_hash(base, name, len); 2496bbddca8eSNeilBrown if (!len) 2497bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2498bbddca8eSNeilBrown 2499bbddca8eSNeilBrown if (unlikely(name[0] == '.')) { 2500bbddca8eSNeilBrown if (len < 2 || (len == 2 && name[1] == '.')) 2501bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2502bbddca8eSNeilBrown } 2503bbddca8eSNeilBrown 2504bbddca8eSNeilBrown while (len--) { 2505bbddca8eSNeilBrown c = *(const unsigned char *)name++; 2506bbddca8eSNeilBrown if (c == '/' || c == '\0') 2507bbddca8eSNeilBrown return ERR_PTR(-EACCES); 2508bbddca8eSNeilBrown } 2509bbddca8eSNeilBrown /* 2510bbddca8eSNeilBrown * See if the low-level filesystem might want 2511bbddca8eSNeilBrown * to use its own hash.. 2512bbddca8eSNeilBrown */ 2513bbddca8eSNeilBrown if (base->d_flags & DCACHE_OP_HASH) { 2514bbddca8eSNeilBrown int err = base->d_op->d_hash(base, &this); 2515bbddca8eSNeilBrown if (err < 0) 2516bbddca8eSNeilBrown return ERR_PTR(err); 2517bbddca8eSNeilBrown } 2518bbddca8eSNeilBrown 2519bbddca8eSNeilBrown err = inode_permission(base->d_inode, MAY_EXEC); 2520bbddca8eSNeilBrown if (err) 2521bbddca8eSNeilBrown return ERR_PTR(err); 2522bbddca8eSNeilBrown 252320d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 252420d00ee8SLinus Torvalds if (!ret) 252520d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 252620d00ee8SLinus Torvalds return ret; 2527bbddca8eSNeilBrown } 2528bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2529bbddca8eSNeilBrown 2530eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2531eedf265aSEric W. Biederman int path_pts(struct path *path) 2532eedf265aSEric W. Biederman { 2533eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2534eedf265aSEric W. Biederman * the input path. 2535eedf265aSEric W. Biederman */ 2536eedf265aSEric W. Biederman struct dentry *child, *parent; 2537eedf265aSEric W. Biederman struct qstr this; 2538eedf265aSEric W. Biederman int ret; 2539eedf265aSEric W. Biederman 2540eedf265aSEric W. Biederman ret = path_parent_directory(path); 2541eedf265aSEric W. Biederman if (ret) 2542eedf265aSEric W. Biederman return ret; 2543eedf265aSEric W. Biederman 2544eedf265aSEric W. Biederman parent = path->dentry; 2545eedf265aSEric W. Biederman this.name = "pts"; 2546eedf265aSEric W. Biederman this.len = 3; 2547eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2548eedf265aSEric W. Biederman if (!child) 2549eedf265aSEric W. Biederman return -ENOENT; 2550eedf265aSEric W. Biederman 2551eedf265aSEric W. Biederman path->dentry = child; 2552eedf265aSEric W. Biederman dput(parent); 2553eedf265aSEric W. Biederman follow_mount(path); 2554eedf265aSEric W. Biederman return 0; 2555eedf265aSEric W. Biederman } 2556eedf265aSEric W. Biederman #endif 2557eedf265aSEric W. Biederman 25581fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25591fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25601da177e4SLinus Torvalds { 2561abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2562abc9f5beSAl Viro flags, path, NULL); 25631da177e4SLinus Torvalds } 2564b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25651fa1e7f6SAndy Whitcroft 25668033426eSJeff Layton /** 2567197df04cSAl Viro * mountpoint_last - look up last component for umount 25688033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25698033426eSJeff Layton * 25708033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25718033426eSJeff Layton * need to resolve the path without doing any revalidation. 25728033426eSJeff Layton * 25738033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25748033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25758033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25768033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25778033426eSJeff Layton * bogus and it doesn't exist. 25788033426eSJeff Layton * 25798033426eSJeff Layton * Returns: 25808033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2581ba8f4613SAl Viro * lookup found a negative dentry. 25828033426eSJeff Layton * 2583ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2584ba8f4613SAl Viro * symlink that needs to be followed. 25858033426eSJeff Layton * 25868033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2587ba8f4613SAl Viro * that needs to be followed. 25888033426eSJeff Layton */ 25898033426eSJeff Layton static int 2590ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 25918033426eSJeff Layton { 25928033426eSJeff Layton int error = 0; 25938033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2594ba8f4613SAl Viro struct path path; 25958033426eSJeff Layton 259635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 259735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 25984675ac39SAl Viro if (unlazy_walk(nd)) 2599deb106c6SAl Viro return -ECHILD; 26008033426eSJeff Layton } 26018033426eSJeff Layton 26028033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 26038033426eSJeff Layton 26048033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 26058033426eSJeff Layton error = handle_dots(nd, nd->last_type); 260635759521SAl Viro if (error) 2607deb106c6SAl Viro return error; 2608ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2609949a852eSAl Viro } else { 2610ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2611ba8f4613SAl Viro if (!path.dentry) { 26128033426eSJeff Layton /* 2613949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2614949a852eSAl Viro * cache, so that means that this dentry is probably 2615949a852eSAl Viro * a symlink or the path doesn't actually point 2616949a852eSAl Viro * to a mounted dentry. 26178033426eSJeff Layton */ 2618ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2619949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2620ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2621ba8f4613SAl Viro return PTR_ERR(path.dentry); 26228033426eSJeff Layton } 2623bcceeebaSDave Jones } 2624ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2625ba8f4613SAl Viro dput(path.dentry); 2626deb106c6SAl Viro return -ENOENT; 262735759521SAl Viro } 2628ba8f4613SAl Viro path.mnt = nd->path.mnt; 26298f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26308033426eSJeff Layton } 26318033426eSJeff Layton 26328033426eSJeff Layton /** 2633197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26342a78b857SMasanari Iida * @nd: lookup context 26358033426eSJeff Layton * @flags: lookup flags 2636c8a53ee5SAl Viro * @path: pointer to container for result 26378033426eSJeff Layton * 26388033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2639606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26408033426eSJeff Layton */ 26418033426eSJeff Layton static int 2642c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26438033426eSJeff Layton { 2644c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2645368ee9baSAl Viro int err; 2646368ee9baSAl Viro if (IS_ERR(s)) 2647368ee9baSAl Viro return PTR_ERR(s); 26483bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2649ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26503bdba28bSAl Viro s = trailing_symlink(nd); 26513bdba28bSAl Viro if (IS_ERR(s)) { 26523bdba28bSAl Viro err = PTR_ERR(s); 26538033426eSJeff Layton break; 26548033426eSJeff Layton } 26553bdba28bSAl Viro } 2656ba8f4613SAl Viro if (!err) { 2657ba8f4613SAl Viro *path = nd->path; 2658ba8f4613SAl Viro nd->path.mnt = NULL; 2659ba8f4613SAl Viro nd->path.dentry = NULL; 2660ba8f4613SAl Viro follow_mount(path); 2661ba8f4613SAl Viro } 2662deb106c6SAl Viro terminate_walk(nd); 26638033426eSJeff Layton return err; 26648033426eSJeff Layton } 26658033426eSJeff Layton 26662d864651SAl Viro static int 2667668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26682d864651SAl Viro unsigned int flags) 26692d864651SAl Viro { 26709883d185SAl Viro struct nameidata nd; 2671cbaab2dbSAl Viro int error; 2672668696dcSAl Viro if (IS_ERR(name)) 2673668696dcSAl Viro return PTR_ERR(name); 26749883d185SAl Viro set_nameidata(&nd, dfd, name); 2675c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26762d864651SAl Viro if (unlikely(error == -ECHILD)) 2677c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26782d864651SAl Viro if (unlikely(error == -ESTALE)) 2679c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26802d864651SAl Viro if (likely(!error)) 2681668696dcSAl Viro audit_inode(name, path->dentry, 0); 26829883d185SAl Viro restore_nameidata(); 2683668696dcSAl Viro putname(name); 26842d864651SAl Viro return error; 26852d864651SAl Viro } 26862d864651SAl Viro 26878033426eSJeff Layton /** 2688197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26898033426eSJeff Layton * @dfd: directory file descriptor 26908033426eSJeff Layton * @name: pathname from userland 26918033426eSJeff Layton * @flags: lookup flags 26928033426eSJeff Layton * @path: pointer to container to hold result 26938033426eSJeff Layton * 26948033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26958033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26968033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26978033426eSJeff Layton * and avoid revalidating the last component. 26988033426eSJeff Layton * 26998033426eSJeff Layton * Returns 0 and populates "path" on success. 27008033426eSJeff Layton */ 27018033426eSJeff Layton int 2702197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 27038033426eSJeff Layton struct path *path) 27048033426eSJeff Layton { 2705cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 27068033426eSJeff Layton } 27078033426eSJeff Layton 27082d864651SAl Viro int 27092d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27102d864651SAl Viro unsigned int flags) 27112d864651SAl Viro { 2712cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27132d864651SAl Viro } 27142d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27152d864651SAl Viro 2716cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27171da177e4SLinus Torvalds { 27188e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2719da9592edSDavid Howells 27208e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27211da177e4SLinus Torvalds return 0; 27228e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27231da177e4SLinus Torvalds return 0; 272423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27251da177e4SLinus Torvalds } 2726cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27271da177e4SLinus Torvalds 27281da177e4SLinus Torvalds /* 27291da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27301da177e4SLinus Torvalds * whether the type of victim is right. 27311da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27321da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27331da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27341da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27351da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27361da177e4SLinus Torvalds * a. be owner of dir, or 27371da177e4SLinus Torvalds * b. be owner of victim, or 27381da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27391da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27401da177e4SLinus Torvalds * links pointing to it. 27410bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27420bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27430bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27440bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27450bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27461da177e4SLinus Torvalds * nfs_async_unlink(). 27471da177e4SLinus Torvalds */ 2748b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27491da177e4SLinus Torvalds { 275063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27511da177e4SLinus Torvalds int error; 27521da177e4SLinus Torvalds 2753b18825a7SDavid Howells if (d_is_negative(victim)) 27541da177e4SLinus Torvalds return -ENOENT; 2755b18825a7SDavid Howells BUG_ON(!inode); 27561da177e4SLinus Torvalds 27571da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27584fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27591da177e4SLinus Torvalds 2760f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27611da177e4SLinus Torvalds if (error) 27621da177e4SLinus Torvalds return error; 27631da177e4SLinus Torvalds if (IS_APPEND(dir)) 27641da177e4SLinus Torvalds return -EPERM; 2765b18825a7SDavid Howells 2766b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27670bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27681da177e4SLinus Torvalds return -EPERM; 27691da177e4SLinus Torvalds if (isdir) { 277044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27711da177e4SLinus Torvalds return -ENOTDIR; 27721da177e4SLinus Torvalds if (IS_ROOT(victim)) 27731da177e4SLinus Torvalds return -EBUSY; 277444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27751da177e4SLinus Torvalds return -EISDIR; 27761da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27771da177e4SLinus Torvalds return -ENOENT; 27781da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27791da177e4SLinus Torvalds return -EBUSY; 27801da177e4SLinus Torvalds return 0; 27811da177e4SLinus Torvalds } 27821da177e4SLinus Torvalds 27831da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27841da177e4SLinus Torvalds * dir. 27851da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27861da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27871da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2788036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2789036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2790036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27911da177e4SLinus Torvalds */ 2792a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27931da177e4SLinus Torvalds { 2794036d5236SEric W. Biederman struct user_namespace *s_user_ns; 279514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27961da177e4SLinus Torvalds if (child->d_inode) 27971da177e4SLinus Torvalds return -EEXIST; 27981da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27991da177e4SLinus Torvalds return -ENOENT; 2800036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2801036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2802036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2803036d5236SEric W. Biederman return -EOVERFLOW; 2804f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 28051da177e4SLinus Torvalds } 28061da177e4SLinus Torvalds 28071da177e4SLinus Torvalds /* 28081da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 28091da177e4SLinus Torvalds */ 28101da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28111da177e4SLinus Torvalds { 28121da177e4SLinus Torvalds struct dentry *p; 28131da177e4SLinus Torvalds 28141da177e4SLinus Torvalds if (p1 == p2) { 28155955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28161da177e4SLinus Torvalds return NULL; 28171da177e4SLinus Torvalds } 28181da177e4SLinus Torvalds 2819fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28201da177e4SLinus Torvalds 2821e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2822e2761a11SOGAWA Hirofumi if (p) { 28235955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28245955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28251da177e4SLinus Torvalds return p; 28261da177e4SLinus Torvalds } 28271da177e4SLinus Torvalds 2828e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2829e2761a11SOGAWA Hirofumi if (p) { 28305955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28315955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28321da177e4SLinus Torvalds return p; 28331da177e4SLinus Torvalds } 28341da177e4SLinus Torvalds 28355955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28365955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28371da177e4SLinus Torvalds return NULL; 28381da177e4SLinus Torvalds } 28394d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28401da177e4SLinus Torvalds 28411da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28421da177e4SLinus Torvalds { 28435955102cSAl Viro inode_unlock(p1->d_inode); 28441da177e4SLinus Torvalds if (p1 != p2) { 28455955102cSAl Viro inode_unlock(p2->d_inode); 2846fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28471da177e4SLinus Torvalds } 28481da177e4SLinus Torvalds } 28494d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28501da177e4SLinus Torvalds 28514acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2852312b63fbSAl Viro bool want_excl) 28531da177e4SLinus Torvalds { 2854a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28551da177e4SLinus Torvalds if (error) 28561da177e4SLinus Torvalds return error; 28571da177e4SLinus Torvalds 2858acfa4380SAl Viro if (!dir->i_op->create) 28591da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28601da177e4SLinus Torvalds mode &= S_IALLUGO; 28611da177e4SLinus Torvalds mode |= S_IFREG; 28621da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28631da177e4SLinus Torvalds if (error) 28641da177e4SLinus Torvalds return error; 2865312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2866a74574aaSStephen Smalley if (!error) 2867f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28681da177e4SLinus Torvalds return error; 28691da177e4SLinus Torvalds } 28704d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28711da177e4SLinus Torvalds 28728e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28738e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28748e6c848eSAl Viro void *arg) 28758e6c848eSAl Viro { 28768e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28778e6c848eSAl Viro int error = may_create(dir, dentry); 28788e6c848eSAl Viro if (error) 28798e6c848eSAl Viro return error; 28808e6c848eSAl Viro 28818e6c848eSAl Viro mode &= S_IALLUGO; 28828e6c848eSAl Viro mode |= S_IFREG; 28838e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28848e6c848eSAl Viro if (error) 28858e6c848eSAl Viro return error; 28868e6c848eSAl Viro error = f(dentry, mode, arg); 28878e6c848eSAl Viro if (!error) 28888e6c848eSAl Viro fsnotify_create(dir, dentry); 28898e6c848eSAl Viro return error; 28908e6c848eSAl Viro } 28918e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28928e6c848eSAl Viro 2893a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2894a2982cc9SEric W. Biederman { 2895a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2896a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2897a2982cc9SEric W. Biederman } 2898a2982cc9SEric W. Biederman 2899f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 29001da177e4SLinus Torvalds { 29013fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 29021da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 29031da177e4SLinus Torvalds int error; 29041da177e4SLinus Torvalds 29051da177e4SLinus Torvalds if (!inode) 29061da177e4SLinus Torvalds return -ENOENT; 29071da177e4SLinus Torvalds 2908c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2909c8fe8f30SChristoph Hellwig case S_IFLNK: 29101da177e4SLinus Torvalds return -ELOOP; 2911c8fe8f30SChristoph Hellwig case S_IFDIR: 2912c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29131da177e4SLinus Torvalds return -EISDIR; 2914c8fe8f30SChristoph Hellwig break; 2915c8fe8f30SChristoph Hellwig case S_IFBLK: 2916c8fe8f30SChristoph Hellwig case S_IFCHR: 2917a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29181da177e4SLinus Torvalds return -EACCES; 2919c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2920c8fe8f30SChristoph Hellwig case S_IFIFO: 2921c8fe8f30SChristoph Hellwig case S_IFSOCK: 29221da177e4SLinus Torvalds flag &= ~O_TRUNC; 2923c8fe8f30SChristoph Hellwig break; 29244a3fd211SDave Hansen } 2925b41572e9SDave Hansen 292662fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2927b41572e9SDave Hansen if (error) 2928b41572e9SDave Hansen return error; 29296146f0d5SMimi Zohar 29301da177e4SLinus Torvalds /* 29311da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29321da177e4SLinus Torvalds */ 29331da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29348737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29357715b521SAl Viro return -EPERM; 29361da177e4SLinus Torvalds if (flag & O_TRUNC) 29377715b521SAl Viro return -EPERM; 29381da177e4SLinus Torvalds } 29391da177e4SLinus Torvalds 29401da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29412e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29427715b521SAl Viro return -EPERM; 29431da177e4SLinus Torvalds 2944f3c7691eSJ. Bruce Fields return 0; 29457715b521SAl Viro } 29467715b521SAl Viro 2947e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29487715b521SAl Viro { 2949f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29507715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29517715b521SAl Viro int error = get_write_access(inode); 29521da177e4SLinus Torvalds if (error) 29537715b521SAl Viro return error; 29541da177e4SLinus Torvalds /* 29551da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29561da177e4SLinus Torvalds */ 2957d7a06983SJeff Layton error = locks_verify_locked(filp); 2958be6d3e56SKentaro Takeda if (!error) 2959ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29601da177e4SLinus Torvalds if (!error) { 29617715b521SAl Viro error = do_truncate(path->dentry, 0, 2962d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2963e1181ee6SJeff Layton filp); 29641da177e4SLinus Torvalds } 29651da177e4SLinus Torvalds put_write_access(inode); 2966acd0c935SMimi Zohar return error; 29671da177e4SLinus Torvalds } 29681da177e4SLinus Torvalds 2969d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2970d57999e1SDave Hansen { 29718a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29728a5e929dSAl Viro flag--; 2973d57999e1SDave Hansen return flag; 2974d57999e1SDave Hansen } 2975d57999e1SDave Hansen 2976d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2977d18e9008SMiklos Szeredi { 29781328c727SSeth Forshee struct user_namespace *s_user_ns; 2979d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2980d18e9008SMiklos Szeredi if (error) 2981d18e9008SMiklos Szeredi return error; 2982d18e9008SMiklos Szeredi 29831328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29841328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29851328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29861328c727SSeth Forshee return -EOVERFLOW; 29871328c727SSeth Forshee 2988d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2989d18e9008SMiklos Szeredi if (error) 2990d18e9008SMiklos Szeredi return error; 2991d18e9008SMiklos Szeredi 2992d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2993d18e9008SMiklos Szeredi } 2994d18e9008SMiklos Szeredi 29951acf0af9SDavid Howells /* 29961acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29971acf0af9SDavid Howells * dentry. 29981acf0af9SDavid Howells * 29991acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 30001acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 30011acf0af9SDavid Howells * 30021acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 30031acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 30041acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 30051acf0af9SDavid Howells * 30061acf0af9SDavid Howells * Returns an error code otherwise. 30071acf0af9SDavid Howells */ 30082675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 300930d90494SAl Viro struct path *path, struct file *file, 3010015c3bbcSMiklos Szeredi const struct open_flags *op, 30111643b43fSAl Viro int open_flag, umode_t mode, 301247237687SAl Viro int *opened) 3013d18e9008SMiklos Szeredi { 3014d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3015d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3016d18e9008SMiklos Szeredi int error; 3017d18e9008SMiklos Szeredi 3018384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3019d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3020d18e9008SMiklos Szeredi 3021d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3022d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3023d18e9008SMiklos Szeredi 302430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 302530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30260fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30270fb1ea09SAl Viro open_to_namei_flags(open_flag), 30280fb1ea09SAl Viro mode, opened); 30296fbd0714SAl Viro d_lookup_done(dentry); 3030384f26e2SAl Viro if (!error) { 3031d18e9008SMiklos Szeredi /* 3032384f26e2SAl Viro * We didn't have the inode before the open, so check open 3033384f26e2SAl Viro * permission here. 3034d18e9008SMiklos Szeredi */ 3035384f26e2SAl Viro int acc_mode = op->acc_mode; 303603da633aSAl Viro if (*opened & FILE_CREATED) { 303703da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 303803da633aSAl Viro fsnotify_create(dir, dentry); 303962fb4a15SAl Viro acc_mode = 0; 304003da633aSAl Viro } 30412675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3042384f26e2SAl Viro if (WARN_ON(error > 0)) 3043384f26e2SAl Viro error = -EINVAL; 3044384f26e2SAl Viro } else if (error > 0) { 3045d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3046d18e9008SMiklos Szeredi error = -EIO; 3047384f26e2SAl Viro } else { 3048d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3049d18e9008SMiklos Szeredi dput(dentry); 3050d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 305110c64ceaSAl Viro } 3052d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3053d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3054a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3055a01e718fSAl Viro error = -ENOENT; 3056a01e718fSAl Viro } else { 3057d18e9008SMiklos Szeredi path->dentry = dentry; 3058d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30592675a4ebSAl Viro return 1; 3060d18e9008SMiklos Szeredi } 3061d18e9008SMiklos Szeredi } 3062a01e718fSAl Viro } 3063d18e9008SMiklos Szeredi dput(dentry); 3064d18e9008SMiklos Szeredi return error; 3065d18e9008SMiklos Szeredi } 3066d18e9008SMiklos Szeredi 306731e6b01fSNick Piggin /* 30681acf0af9SDavid Howells * Look up and maybe create and open the last component. 3069d58ffd35SMiklos Szeredi * 3070d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3071d58ffd35SMiklos Szeredi * 30721acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30731acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30741acf0af9SDavid Howells * 30751acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30761acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30771acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30781acf0af9SDavid Howells * specified then a negative dentry may be returned. 30791acf0af9SDavid Howells * 30801acf0af9SDavid Howells * An error code is returned otherwise. 30811acf0af9SDavid Howells * 30821acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30831acf0af9SDavid Howells * cleared otherwise prior to returning. 3084d58ffd35SMiklos Szeredi */ 30852675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 308630d90494SAl Viro struct file *file, 3087d58ffd35SMiklos Szeredi const struct open_flags *op, 308864894cf8SAl Viro bool got_write, int *opened) 3089d58ffd35SMiklos Szeredi { 3090d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 309154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30921643b43fSAl Viro int open_flag = op->open_flag; 3093d58ffd35SMiklos Szeredi struct dentry *dentry; 30941643b43fSAl Viro int error, create_error = 0; 30951643b43fSAl Viro umode_t mode = op->mode; 30966fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3097d58ffd35SMiklos Szeredi 3098ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3099ce8644fcSAl Viro return -ENOENT; 3100d58ffd35SMiklos Szeredi 310147237687SAl Viro *opened &= ~FILE_CREATED; 31026fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 31036fbd0714SAl Viro for (;;) { 31046fbd0714SAl Viro if (!dentry) { 31056fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3106d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 31072675a4ebSAl Viro return PTR_ERR(dentry); 31086fbd0714SAl Viro } 31096fbd0714SAl Viro if (d_in_lookup(dentry)) 31106fbd0714SAl Viro break; 3111d58ffd35SMiklos Szeredi 31126fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31136fbd0714SAl Viro if (likely(error > 0)) 31146fbd0714SAl Viro break; 31156fbd0714SAl Viro if (error) 31166fbd0714SAl Viro goto out_dput; 31176fbd0714SAl Viro d_invalidate(dentry); 31186fbd0714SAl Viro dput(dentry); 31196fbd0714SAl Viro dentry = NULL; 31206fbd0714SAl Viro } 31216fbd0714SAl Viro if (dentry->d_inode) { 3122d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3123d18e9008SMiklos Szeredi goto out_no_open; 31246c51e513SAl Viro } 3125d18e9008SMiklos Szeredi 31261643b43fSAl Viro /* 31271643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31281643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31291643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31301643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31311643b43fSAl Viro * 31321643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31331643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31341643b43fSAl Viro */ 31351643b43fSAl Viro if (open_flag & O_CREAT) { 31361643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31371643b43fSAl Viro mode &= ~current_umask(); 31381643b43fSAl Viro if (unlikely(!got_write)) { 31391643b43fSAl Viro create_error = -EROFS; 31401643b43fSAl Viro open_flag &= ~O_CREAT; 31411643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31421643b43fSAl Viro goto no_open; 31431643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31441643b43fSAl Viro } else { 31451643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31461643b43fSAl Viro if (create_error) { 31471643b43fSAl Viro open_flag &= ~O_CREAT; 31481643b43fSAl Viro if (open_flag & O_EXCL) 31491643b43fSAl Viro goto no_open; 31501643b43fSAl Viro } 31511643b43fSAl Viro } 31521643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31531643b43fSAl Viro unlikely(!got_write)) { 31541643b43fSAl Viro /* 31551643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31561643b43fSAl Viro * back to lookup + open 31571643b43fSAl Viro */ 31581643b43fSAl Viro goto no_open; 3159d18e9008SMiklos Szeredi } 3160d18e9008SMiklos Szeredi 31611643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31621643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31631643b43fSAl Viro mode, opened); 31641643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31651643b43fSAl Viro error = create_error; 31661643b43fSAl Viro return error; 31671643b43fSAl Viro } 316854ef4872SMiklos Szeredi 31691643b43fSAl Viro no_open: 31706fbd0714SAl Viro if (d_in_lookup(dentry)) { 317112fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 317212fa5e24SAl Viro nd->flags); 31736fbd0714SAl Viro d_lookup_done(dentry); 317412fa5e24SAl Viro if (unlikely(res)) { 317512fa5e24SAl Viro if (IS_ERR(res)) { 317612fa5e24SAl Viro error = PTR_ERR(res); 317712fa5e24SAl Viro goto out_dput; 317812fa5e24SAl Viro } 317912fa5e24SAl Viro dput(dentry); 318012fa5e24SAl Viro dentry = res; 318112fa5e24SAl Viro } 318254ef4872SMiklos Szeredi } 318354ef4872SMiklos Szeredi 3184d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31851643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 318647237687SAl Viro *opened |= FILE_CREATED; 3187ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3188ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3189ce8644fcSAl Viro error = -EACCES; 3190d58ffd35SMiklos Szeredi goto out_dput; 319177d660a8SMiklos Szeredi } 3192ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31931643b43fSAl Viro open_flag & O_EXCL); 3194d58ffd35SMiklos Szeredi if (error) 3195d58ffd35SMiklos Szeredi goto out_dput; 3196ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3197d58ffd35SMiklos Szeredi } 31981643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31991643b43fSAl Viro error = create_error; 3200d58ffd35SMiklos Szeredi goto out_dput; 3201d58ffd35SMiklos Szeredi } 3202d18e9008SMiklos Szeredi out_no_open: 3203d58ffd35SMiklos Szeredi path->dentry = dentry; 3204d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 32052675a4ebSAl Viro return 1; 3206d58ffd35SMiklos Szeredi 3207d58ffd35SMiklos Szeredi out_dput: 3208d58ffd35SMiklos Szeredi dput(dentry); 32092675a4ebSAl Viro return error; 3210d58ffd35SMiklos Szeredi } 3211d58ffd35SMiklos Szeredi 3212d58ffd35SMiklos Szeredi /* 3213fe2d35ffSAl Viro * Handle the last step of open() 321431e6b01fSNick Piggin */ 3215896475d5SAl Viro static int do_last(struct nameidata *nd, 321630d90494SAl Viro struct file *file, const struct open_flags *op, 321776ae2a5aSAl Viro int *opened) 3218fb1cc555SAl Viro { 3219a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3220ca344a89SAl Viro int open_flag = op->open_flag; 322177d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 322264894cf8SAl Viro bool got_write = false; 3223bcda7652SAl Viro int acc_mode = op->acc_mode; 3224254cf582SAl Viro unsigned seq; 3225a1eb3315SMiklos Szeredi struct inode *inode; 3226896475d5SAl Viro struct path path; 322716c2cd71SAl Viro int error; 3228fb1cc555SAl Viro 3229c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3230c3e380b0SAl Viro nd->flags |= op->intent; 3231c3e380b0SAl Viro 3232bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3233fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3234deb106c6SAl Viro if (unlikely(error)) 32352675a4ebSAl Viro return error; 3236e83db167SMiklos Szeredi goto finish_open; 32371f36f774SAl Viro } 3238a2c36b45SAl Viro 3239ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3240fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3241fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3242fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3243254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3244e9742b53SAl Viro if (likely(error > 0)) 324571574865SMiklos Szeredi goto finish_lookup; 324671574865SMiklos Szeredi 3247ce57dfc1SAl Viro if (error < 0) 3248deb106c6SAl Viro return error; 3249a1eb3315SMiklos Szeredi 325037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32516583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3252b6183df7SMiklos Szeredi } else { 3253fe2d35ffSAl Viro /* create side of things */ 3254a3fbbde7SAl Viro /* 3255b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3256b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3257b6183df7SMiklos Szeredi * about to look up 3258a3fbbde7SAl Viro */ 32599f1fafeeSAl Viro error = complete_walk(nd); 3260e8bb73dfSAl Viro if (error) 32612675a4ebSAl Viro return error; 3262fe2d35ffSAl Viro 326376ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32641f36f774SAl Viro /* trailing slashes? */ 3265deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3266deb106c6SAl Viro return -EISDIR; 3267b6183df7SMiklos Szeredi } 32681f36f774SAl Viro 32699cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 327064894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 327164894cf8SAl Viro if (!error) 327264894cf8SAl Viro got_write = true; 327364894cf8SAl Viro /* 327464894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 327564894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 327664894cf8SAl Viro * dropping this one anyway. 327764894cf8SAl Viro */ 327864894cf8SAl Viro } 32799cf843e3SAl Viro if (open_flag & O_CREAT) 32805955102cSAl Viro inode_lock(dir->d_inode); 32819cf843e3SAl Viro else 32829cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3283896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32849cf843e3SAl Viro if (open_flag & O_CREAT) 32855955102cSAl Viro inode_unlock(dir->d_inode); 32869cf843e3SAl Viro else 32879cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3288fb1cc555SAl Viro 32892675a4ebSAl Viro if (error <= 0) { 32902675a4ebSAl Viro if (error) 3291d58ffd35SMiklos Szeredi goto out; 32926c0d46c4SAl Viro 329347237687SAl Viro if ((*opened & FILE_CREATED) || 3294496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 329577d660a8SMiklos Szeredi will_truncate = false; 3296d18e9008SMiklos Szeredi 329776ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3298d18e9008SMiklos Szeredi goto opened; 3299d18e9008SMiklos Szeredi } 3300d18e9008SMiklos Szeredi 330147237687SAl Viro if (*opened & FILE_CREATED) { 33029b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3303ca344a89SAl Viro open_flag &= ~O_TRUNC; 330477d660a8SMiklos Szeredi will_truncate = false; 330562fb4a15SAl Viro acc_mode = 0; 3306896475d5SAl Viro path_to_nameidata(&path, nd); 3307e83db167SMiklos Szeredi goto finish_open_created; 3308fb1cc555SAl Viro } 3309fb1cc555SAl Viro 3310fb1cc555SAl Viro /* 3311d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3312d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3313d18e9008SMiklos Szeredi * necessary...) 3314d18e9008SMiklos Szeredi */ 331564894cf8SAl Viro if (got_write) { 3316d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 331764894cf8SAl Viro got_write = false; 3318d18e9008SMiklos Szeredi } 3319d18e9008SMiklos Szeredi 3320e6ec03a2SAl Viro error = follow_managed(&path, nd); 3321e6ec03a2SAl Viro if (unlikely(error < 0)) 3322e6ec03a2SAl Viro return error; 3323e6ec03a2SAl Viro 33246583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33256583fe22SAl Viro path_to_nameidata(&path, nd); 33266583fe22SAl Viro return -ENOENT; 33276583fe22SAl Viro } 33286583fe22SAl Viro 33296583fe22SAl Viro /* 33306583fe22SAl Viro * create/update audit record if it already exists. 33316583fe22SAl Viro */ 33326583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33336583fe22SAl Viro 3334deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3335deb106c6SAl Viro path_to_nameidata(&path, nd); 3336deb106c6SAl Viro return -EEXIST; 3337deb106c6SAl Viro } 3338fb1cc555SAl Viro 3339254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3340d4565649SAl Viro inode = d_backing_inode(path.dentry); 3341766c4cbfSAl Viro finish_lookup: 33428f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3343deb106c6SAl Viro if (unlikely(error)) 3344d63ff28fSAl Viro return error; 3345bc77daa7SAl Viro finish_open: 33468f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3347a3fbbde7SAl Viro error = complete_walk(nd); 3348fac7d191SAl Viro if (error) 33492675a4ebSAl Viro return error; 335076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3351fb1cc555SAl Viro error = -EISDIR; 335244b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33532675a4ebSAl Viro goto out; 3354af2f5542SMiklos Szeredi error = -ENOTDIR; 335544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33562675a4ebSAl Viro goto out; 33574bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 335877d660a8SMiklos Szeredi will_truncate = false; 33596c0d46c4SAl Viro 33600f9d1a10SAl Viro if (will_truncate) { 33610f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33620f9d1a10SAl Viro if (error) 33632675a4ebSAl Viro goto out; 336464894cf8SAl Viro got_write = true; 33650f9d1a10SAl Viro } 3366e83db167SMiklos Szeredi finish_open_created: 3367bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3368ca344a89SAl Viro if (error) 33692675a4ebSAl Viro goto out; 33704aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33714aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3372fac7d191SAl Viro if (error) 3373015c3bbcSMiklos Szeredi goto out; 3374fac7d191SAl Viro *opened |= FILE_OPENED; 3375a8277b9bSMiklos Szeredi opened: 33762675a4ebSAl Viro error = open_check_o_direct(file); 3377fe9ec829SAl Viro if (!error) 33783034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3379fe9ec829SAl Viro if (!error && will_truncate) 33802675a4ebSAl Viro error = handle_truncate(file); 3381ca344a89SAl Viro out: 3382fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3383fe9ec829SAl Viro fput(file); 3384c80567c8SAl Viro if (unlikely(error > 0)) { 3385c80567c8SAl Viro WARN_ON(1); 3386c80567c8SAl Viro error = -EINVAL; 3387c80567c8SAl Viro } 338864894cf8SAl Viro if (got_write) 33890f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33902675a4ebSAl Viro return error; 3391fb1cc555SAl Viro } 3392fb1cc555SAl Viro 3393af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3394af7bd4dcSAmir Goldstein { 3395af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3396af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3397af7bd4dcSAmir Goldstein struct inode *inode; 3398af7bd4dcSAmir Goldstein int error; 3399af7bd4dcSAmir Goldstein 3400af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3401af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3402af7bd4dcSAmir Goldstein if (error) 3403af7bd4dcSAmir Goldstein goto out_err; 3404af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3405af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3406af7bd4dcSAmir Goldstein goto out_err; 3407af7bd4dcSAmir Goldstein error = -ENOMEM; 3408cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3409af7bd4dcSAmir Goldstein if (unlikely(!child)) 3410af7bd4dcSAmir Goldstein goto out_err; 3411af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3412af7bd4dcSAmir Goldstein if (error) 3413af7bd4dcSAmir Goldstein goto out_err; 3414af7bd4dcSAmir Goldstein error = -ENOENT; 3415af7bd4dcSAmir Goldstein inode = child->d_inode; 3416af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3417af7bd4dcSAmir Goldstein goto out_err; 3418af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3419af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3420af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3421af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3422af7bd4dcSAmir Goldstein } 3423af7bd4dcSAmir Goldstein return child; 3424af7bd4dcSAmir Goldstein 3425af7bd4dcSAmir Goldstein out_err: 3426af7bd4dcSAmir Goldstein dput(child); 3427af7bd4dcSAmir Goldstein return ERR_PTR(error); 3428af7bd4dcSAmir Goldstein } 3429af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3430af7bd4dcSAmir Goldstein 3431c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 343260545d0dSAl Viro const struct open_flags *op, 343360545d0dSAl Viro struct file *file, int *opened) 343460545d0dSAl Viro { 3435625b6d10SAl Viro struct dentry *child; 3436625b6d10SAl Viro struct path path; 3437c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 343860545d0dSAl Viro if (unlikely(error)) 343960545d0dSAl Viro return error; 3440625b6d10SAl Viro error = mnt_want_write(path.mnt); 344160545d0dSAl Viro if (unlikely(error)) 344260545d0dSAl Viro goto out; 3443af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3444af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3445684e73beSHirofumi Nakagawa if (IS_ERR(child)) 344660545d0dSAl Viro goto out2; 3447625b6d10SAl Viro dput(path.dentry); 3448625b6d10SAl Viro path.dentry = child; 3449c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 345069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 345162fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 345260545d0dSAl Viro if (error) 345360545d0dSAl Viro goto out2; 3454625b6d10SAl Viro file->f_path.mnt = path.mnt; 3455625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 345660545d0dSAl Viro if (error) 345760545d0dSAl Viro goto out2; 345860545d0dSAl Viro error = open_check_o_direct(file); 3459af7bd4dcSAmir Goldstein if (error) 346060545d0dSAl Viro fput(file); 346160545d0dSAl Viro out2: 3462625b6d10SAl Viro mnt_drop_write(path.mnt); 346360545d0dSAl Viro out: 3464625b6d10SAl Viro path_put(&path); 346560545d0dSAl Viro return error; 346660545d0dSAl Viro } 346760545d0dSAl Viro 34686ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34696ac08709SAl Viro { 34706ac08709SAl Viro struct path path; 34716ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34726ac08709SAl Viro if (!error) { 34736ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34746ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34756ac08709SAl Viro path_put(&path); 34766ac08709SAl Viro } 34776ac08709SAl Viro return error; 34786ac08709SAl Viro } 34796ac08709SAl Viro 3480c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3481c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34821da177e4SLinus Torvalds { 3483368ee9baSAl Viro const char *s; 348430d90494SAl Viro struct file *file; 348547237687SAl Viro int opened = 0; 348613aab428SAl Viro int error; 348731e6b01fSNick Piggin 348830d90494SAl Viro file = get_empty_filp(); 34891afc99beSAl Viro if (IS_ERR(file)) 34901afc99beSAl Viro return file; 349131e6b01fSNick Piggin 349230d90494SAl Viro file->f_flags = op->open_flag; 349331e6b01fSNick Piggin 3494bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3495c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3496f15133dfSAl Viro goto out2; 349760545d0dSAl Viro } 349860545d0dSAl Viro 34996ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 35006ac08709SAl Viro error = do_o_path(nd, flags, file); 35016ac08709SAl Viro if (!error) 35026ac08709SAl Viro opened |= FILE_OPENED; 35036ac08709SAl Viro goto out2; 35046ac08709SAl Viro } 35056ac08709SAl Viro 3506c8a53ee5SAl Viro s = path_init(nd, flags); 3507368ee9baSAl Viro if (IS_ERR(s)) { 3508368ee9baSAl Viro put_filp(file); 3509368ee9baSAl Viro return ERR_CAST(s); 3510368ee9baSAl Viro } 35113bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 351276ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 351373d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35143bdba28bSAl Viro s = trailing_symlink(nd); 35153bdba28bSAl Viro if (IS_ERR(s)) { 35163bdba28bSAl Viro error = PTR_ERR(s); 35172675a4ebSAl Viro break; 3518806b681cSAl Viro } 35193bdba28bSAl Viro } 3520deb106c6SAl Viro terminate_walk(nd); 3521f15133dfSAl Viro out2: 35222675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35232675a4ebSAl Viro BUG_ON(!error); 352430d90494SAl Viro put_filp(file); 3525015c3bbcSMiklos Szeredi } 35262675a4ebSAl Viro if (unlikely(error)) { 35272675a4ebSAl Viro if (error == -EOPENSTALE) { 35282675a4ebSAl Viro if (flags & LOOKUP_RCU) 35292675a4ebSAl Viro error = -ECHILD; 35302675a4ebSAl Viro else 35312675a4ebSAl Viro error = -ESTALE; 35322675a4ebSAl Viro } 35332675a4ebSAl Viro file = ERR_PTR(error); 35342675a4ebSAl Viro } 35352675a4ebSAl Viro return file; 3536de459215SKirill Korotaev } 35371da177e4SLinus Torvalds 3538669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3539f9652e10SAl Viro const struct open_flags *op) 354013aab428SAl Viro { 35419883d185SAl Viro struct nameidata nd; 3542f9652e10SAl Viro int flags = op->lookup_flags; 354313aab428SAl Viro struct file *filp; 354413aab428SAl Viro 35459883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3546c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 354713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3548c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 354913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3550c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35519883d185SAl Viro restore_nameidata(); 355213aab428SAl Viro return filp; 355313aab428SAl Viro } 355413aab428SAl Viro 355573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3556f9652e10SAl Viro const char *name, const struct open_flags *op) 355773d049a4SAl Viro { 35589883d185SAl Viro struct nameidata nd; 355973d049a4SAl Viro struct file *file; 356051689104SPaul Moore struct filename *filename; 3561f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 356273d049a4SAl Viro 356373d049a4SAl Viro nd.root.mnt = mnt; 356473d049a4SAl Viro nd.root.dentry = dentry; 356573d049a4SAl Viro 3566b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 356773d049a4SAl Viro return ERR_PTR(-ELOOP); 356873d049a4SAl Viro 356951689104SPaul Moore filename = getname_kernel(name); 3570a1c83681SViresh Kumar if (IS_ERR(filename)) 357151689104SPaul Moore return ERR_CAST(filename); 357251689104SPaul Moore 35739883d185SAl Viro set_nameidata(&nd, -1, filename); 3574c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 357573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3576c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 357773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3578c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35799883d185SAl Viro restore_nameidata(); 358051689104SPaul Moore putname(filename); 358173d049a4SAl Viro return file; 358273d049a4SAl Viro } 358373d049a4SAl Viro 3584fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35851ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35861da177e4SLinus Torvalds { 3587c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3588391172c4SAl Viro struct qstr last; 3589391172c4SAl Viro int type; 3590c30dabfeSJan Kara int err2; 35911ac12b4bSJeff Layton int error; 35921ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35931ac12b4bSJeff Layton 35941ac12b4bSJeff Layton /* 35951ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35961ac12b4bSJeff Layton * other flags passed in are ignored! 35971ac12b4bSJeff Layton */ 35981ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35991ac12b4bSJeff Layton 36005c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 36015c31b6ceSAl Viro if (IS_ERR(name)) 36025c31b6ceSAl Viro return ERR_CAST(name); 36031da177e4SLinus Torvalds 3604c663e5d8SChristoph Hellwig /* 3605c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3606c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3607c663e5d8SChristoph Hellwig */ 36085c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3609ed75e95dSAl Viro goto out; 3610c663e5d8SChristoph Hellwig 3611c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3612391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3613c663e5d8SChristoph Hellwig /* 3614c663e5d8SChristoph Hellwig * Do the final lookup. 3615c663e5d8SChristoph Hellwig */ 3616391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36175955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3618391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36191da177e4SLinus Torvalds if (IS_ERR(dentry)) 3620a8104a9fSAl Viro goto unlock; 3621c663e5d8SChristoph Hellwig 3622a8104a9fSAl Viro error = -EEXIST; 3623b18825a7SDavid Howells if (d_is_positive(dentry)) 3624a8104a9fSAl Viro goto fail; 3625b18825a7SDavid Howells 3626c663e5d8SChristoph Hellwig /* 3627c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3628c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3629c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3630c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3631c663e5d8SChristoph Hellwig */ 3632391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3633a8104a9fSAl Viro error = -ENOENT; 3634ed75e95dSAl Viro goto fail; 3635e9baf6e5SAl Viro } 3636c30dabfeSJan Kara if (unlikely(err2)) { 3637c30dabfeSJan Kara error = err2; 3638a8104a9fSAl Viro goto fail; 3639c30dabfeSJan Kara } 3640181c37b6SAl Viro putname(name); 3641e9baf6e5SAl Viro return dentry; 36421da177e4SLinus Torvalds fail: 3643a8104a9fSAl Viro dput(dentry); 3644a8104a9fSAl Viro dentry = ERR_PTR(error); 3645a8104a9fSAl Viro unlock: 36465955102cSAl Viro inode_unlock(path->dentry->d_inode); 3647c30dabfeSJan Kara if (!err2) 3648391172c4SAl Viro mnt_drop_write(path->mnt); 3649ed75e95dSAl Viro out: 3650391172c4SAl Viro path_put(path); 3651181c37b6SAl Viro putname(name); 3652ed75e95dSAl Viro return dentry; 3653dae6ad8fSAl Viro } 3654fa14a0b8SAl Viro 3655fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3656fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3657fa14a0b8SAl Viro { 3658181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3659181c37b6SAl Viro path, lookup_flags); 3660fa14a0b8SAl Viro } 3661dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3662dae6ad8fSAl Viro 3663921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3664921a1650SAl Viro { 3665921a1650SAl Viro dput(dentry); 36665955102cSAl Viro inode_unlock(path->dentry->d_inode); 3667a8104a9fSAl Viro mnt_drop_write(path->mnt); 3668921a1650SAl Viro path_put(path); 3669921a1650SAl Viro } 3670921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3671921a1650SAl Viro 3672520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36731ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3674dae6ad8fSAl Viro { 3675181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3676dae6ad8fSAl Viro } 3677dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3678dae6ad8fSAl Viro 36791a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36801da177e4SLinus Torvalds { 3681a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36821da177e4SLinus Torvalds 36831da177e4SLinus Torvalds if (error) 36841da177e4SLinus Torvalds return error; 36851da177e4SLinus Torvalds 3686975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36871da177e4SLinus Torvalds return -EPERM; 36881da177e4SLinus Torvalds 3689acfa4380SAl Viro if (!dir->i_op->mknod) 36901da177e4SLinus Torvalds return -EPERM; 36911da177e4SLinus Torvalds 369208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 369308ce5f16SSerge E. Hallyn if (error) 369408ce5f16SSerge E. Hallyn return error; 369508ce5f16SSerge E. Hallyn 36961da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36971da177e4SLinus Torvalds if (error) 36981da177e4SLinus Torvalds return error; 36991da177e4SLinus Torvalds 37001da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3701a74574aaSStephen Smalley if (!error) 3702f38aa942SAmy Griffis fsnotify_create(dir, dentry); 37031da177e4SLinus Torvalds return error; 37041da177e4SLinus Torvalds } 37054d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 37061da177e4SLinus Torvalds 3707f69aac00SAl Viro static int may_mknod(umode_t mode) 3708463c3197SDave Hansen { 3709463c3197SDave Hansen switch (mode & S_IFMT) { 3710463c3197SDave Hansen case S_IFREG: 3711463c3197SDave Hansen case S_IFCHR: 3712463c3197SDave Hansen case S_IFBLK: 3713463c3197SDave Hansen case S_IFIFO: 3714463c3197SDave Hansen case S_IFSOCK: 3715463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3716463c3197SDave Hansen return 0; 3717463c3197SDave Hansen case S_IFDIR: 3718463c3197SDave Hansen return -EPERM; 3719463c3197SDave Hansen default: 3720463c3197SDave Hansen return -EINVAL; 3721463c3197SDave Hansen } 3722463c3197SDave Hansen } 3723463c3197SDave Hansen 37248208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37252e4d0924SHeiko Carstens unsigned, dev) 37261da177e4SLinus Torvalds { 37271da177e4SLinus Torvalds struct dentry *dentry; 3728dae6ad8fSAl Viro struct path path; 3729dae6ad8fSAl Viro int error; 3730972567f1SJeff Layton unsigned int lookup_flags = 0; 37311da177e4SLinus Torvalds 37328e4bfca1SAl Viro error = may_mknod(mode); 37338e4bfca1SAl Viro if (error) 37348e4bfca1SAl Viro return error; 3735972567f1SJeff Layton retry: 3736972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3737dae6ad8fSAl Viro if (IS_ERR(dentry)) 3738dae6ad8fSAl Viro return PTR_ERR(dentry); 37392ad94ae6SAl Viro 3740dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3741ce3b0f8dSAl Viro mode &= ~current_umask(); 3742dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3743be6d3e56SKentaro Takeda if (error) 3744a8104a9fSAl Viro goto out; 37451da177e4SLinus Torvalds switch (mode & S_IFMT) { 37461da177e4SLinus Torvalds case 0: case S_IFREG: 3747312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 374805d1a717SMimi Zohar if (!error) 374905d1a717SMimi Zohar ima_post_path_mknod(dentry); 37501da177e4SLinus Torvalds break; 37511da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3752dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37531da177e4SLinus Torvalds new_decode_dev(dev)); 37541da177e4SLinus Torvalds break; 37551da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3756dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37571da177e4SLinus Torvalds break; 37581da177e4SLinus Torvalds } 3759a8104a9fSAl Viro out: 3760921a1650SAl Viro done_path_create(&path, dentry); 3761972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3762972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3763972567f1SJeff Layton goto retry; 3764972567f1SJeff Layton } 37651da177e4SLinus Torvalds return error; 37661da177e4SLinus Torvalds } 37671da177e4SLinus Torvalds 37688208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37695590ff0dSUlrich Drepper { 37705590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37715590ff0dSUlrich Drepper } 37725590ff0dSUlrich Drepper 377318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37741da177e4SLinus Torvalds { 3775a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37768de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37771da177e4SLinus Torvalds 37781da177e4SLinus Torvalds if (error) 37791da177e4SLinus Torvalds return error; 37801da177e4SLinus Torvalds 3781acfa4380SAl Viro if (!dir->i_op->mkdir) 37821da177e4SLinus Torvalds return -EPERM; 37831da177e4SLinus Torvalds 37841da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37851da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37861da177e4SLinus Torvalds if (error) 37871da177e4SLinus Torvalds return error; 37881da177e4SLinus Torvalds 37898de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37908de52778SAl Viro return -EMLINK; 37918de52778SAl Viro 37921da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3793a74574aaSStephen Smalley if (!error) 3794f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37951da177e4SLinus Torvalds return error; 37961da177e4SLinus Torvalds } 37974d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37981da177e4SLinus Torvalds 3799a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 38001da177e4SLinus Torvalds { 38016902d925SDave Hansen struct dentry *dentry; 3802dae6ad8fSAl Viro struct path path; 3803dae6ad8fSAl Viro int error; 3804b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 38051da177e4SLinus Torvalds 3806b76d8b82SJeff Layton retry: 3807b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 38086902d925SDave Hansen if (IS_ERR(dentry)) 3809dae6ad8fSAl Viro return PTR_ERR(dentry); 38106902d925SDave Hansen 3811dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3812ce3b0f8dSAl Viro mode &= ~current_umask(); 3813dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3814a8104a9fSAl Viro if (!error) 3815dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3816921a1650SAl Viro done_path_create(&path, dentry); 3817b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3818b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3819b76d8b82SJeff Layton goto retry; 3820b76d8b82SJeff Layton } 38211da177e4SLinus Torvalds return error; 38221da177e4SLinus Torvalds } 38231da177e4SLinus Torvalds 3824a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38255590ff0dSUlrich Drepper { 38265590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38275590ff0dSUlrich Drepper } 38285590ff0dSUlrich Drepper 38291da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38301da177e4SLinus Torvalds { 38311da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38321da177e4SLinus Torvalds 38331da177e4SLinus Torvalds if (error) 38341da177e4SLinus Torvalds return error; 38351da177e4SLinus Torvalds 3836acfa4380SAl Viro if (!dir->i_op->rmdir) 38371da177e4SLinus Torvalds return -EPERM; 38381da177e4SLinus Torvalds 38391d2ef590SAl Viro dget(dentry); 38405955102cSAl Viro inode_lock(dentry->d_inode); 3841912dbc15SSage Weil 38421da177e4SLinus Torvalds error = -EBUSY; 38437af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3844912dbc15SSage Weil goto out; 3845912dbc15SSage Weil 38461da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3847912dbc15SSage Weil if (error) 3848912dbc15SSage Weil goto out; 3849912dbc15SSage Weil 38503cebde24SSage Weil shrink_dcache_parent(dentry); 38511da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3852912dbc15SSage Weil if (error) 3853912dbc15SSage Weil goto out; 3854912dbc15SSage Weil 38551da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3856d83c49f3SAl Viro dont_mount(dentry); 38578ed936b5SEric W. Biederman detach_mounts(dentry); 38581da177e4SLinus Torvalds 3859912dbc15SSage Weil out: 38605955102cSAl Viro inode_unlock(dentry->d_inode); 38611d2ef590SAl Viro dput(dentry); 3862912dbc15SSage Weil if (!error) 3863912dbc15SSage Weil d_delete(dentry); 38641da177e4SLinus Torvalds return error; 38651da177e4SLinus Torvalds } 38664d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38671da177e4SLinus Torvalds 38685590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38691da177e4SLinus Torvalds { 38701da177e4SLinus Torvalds int error = 0; 387191a27b2aSJeff Layton struct filename *name; 38721da177e4SLinus Torvalds struct dentry *dentry; 3873f5beed75SAl Viro struct path path; 3874f5beed75SAl Viro struct qstr last; 3875f5beed75SAl Viro int type; 3876c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3877c6ee9206SJeff Layton retry: 3878c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3879c1d4dd27SAl Viro &path, &last, &type); 388091a27b2aSJeff Layton if (IS_ERR(name)) 388191a27b2aSJeff Layton return PTR_ERR(name); 38821da177e4SLinus Torvalds 3883f5beed75SAl Viro switch (type) { 38841da177e4SLinus Torvalds case LAST_DOTDOT: 38851da177e4SLinus Torvalds error = -ENOTEMPTY; 38861da177e4SLinus Torvalds goto exit1; 38871da177e4SLinus Torvalds case LAST_DOT: 38881da177e4SLinus Torvalds error = -EINVAL; 38891da177e4SLinus Torvalds goto exit1; 38901da177e4SLinus Torvalds case LAST_ROOT: 38911da177e4SLinus Torvalds error = -EBUSY; 38921da177e4SLinus Torvalds goto exit1; 38931da177e4SLinus Torvalds } 38940612d9fbSOGAWA Hirofumi 3895f5beed75SAl Viro error = mnt_want_write(path.mnt); 3896c30dabfeSJan Kara if (error) 3897c30dabfeSJan Kara goto exit1; 38980612d9fbSOGAWA Hirofumi 38995955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3900f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39011da177e4SLinus Torvalds error = PTR_ERR(dentry); 39026902d925SDave Hansen if (IS_ERR(dentry)) 39036902d925SDave Hansen goto exit2; 3904e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3905e6bc45d6STheodore Ts'o error = -ENOENT; 3906e6bc45d6STheodore Ts'o goto exit3; 3907e6bc45d6STheodore Ts'o } 3908f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3909be6d3e56SKentaro Takeda if (error) 3910c30dabfeSJan Kara goto exit3; 3911f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39120622753bSDave Hansen exit3: 39131da177e4SLinus Torvalds dput(dentry); 39146902d925SDave Hansen exit2: 39155955102cSAl Viro inode_unlock(path.dentry->d_inode); 3916f5beed75SAl Viro mnt_drop_write(path.mnt); 39171da177e4SLinus Torvalds exit1: 3918f5beed75SAl Viro path_put(&path); 39191da177e4SLinus Torvalds putname(name); 3920c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3921c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3922c6ee9206SJeff Layton goto retry; 3923c6ee9206SJeff Layton } 39241da177e4SLinus Torvalds return error; 39251da177e4SLinus Torvalds } 39261da177e4SLinus Torvalds 39273cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39285590ff0dSUlrich Drepper { 39295590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39305590ff0dSUlrich Drepper } 39315590ff0dSUlrich Drepper 3932b21996e3SJ. Bruce Fields /** 3933b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3934b21996e3SJ. Bruce Fields * @dir: parent directory 3935b21996e3SJ. Bruce Fields * @dentry: victim 3936b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3937b21996e3SJ. Bruce Fields * 3938b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3939b21996e3SJ. Bruce Fields * 3940b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3941b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3942b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3943b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3944b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3945b21996e3SJ. Bruce Fields * 3946b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3947b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3948b21996e3SJ. Bruce Fields * to be NFS exported. 3949b21996e3SJ. Bruce Fields */ 3950b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39511da177e4SLinus Torvalds { 39529accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39531da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39541da177e4SLinus Torvalds 39551da177e4SLinus Torvalds if (error) 39561da177e4SLinus Torvalds return error; 39571da177e4SLinus Torvalds 3958acfa4380SAl Viro if (!dir->i_op->unlink) 39591da177e4SLinus Torvalds return -EPERM; 39601da177e4SLinus Torvalds 39615955102cSAl Viro inode_lock(target); 39628ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39631da177e4SLinus Torvalds error = -EBUSY; 39641da177e4SLinus Torvalds else { 39651da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3966bec1052eSAl Viro if (!error) { 39675a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39685a14696cSJ. Bruce Fields if (error) 3969b21996e3SJ. Bruce Fields goto out; 39701da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39718ed936b5SEric W. Biederman if (!error) { 3972d83c49f3SAl Viro dont_mount(dentry); 39738ed936b5SEric W. Biederman detach_mounts(dentry); 39748ed936b5SEric W. Biederman } 3975bec1052eSAl Viro } 39761da177e4SLinus Torvalds } 3977b21996e3SJ. Bruce Fields out: 39785955102cSAl Viro inode_unlock(target); 39791da177e4SLinus Torvalds 39801da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39811da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39829accbb97SJ. Bruce Fields fsnotify_link_count(target); 39831da177e4SLinus Torvalds d_delete(dentry); 39841da177e4SLinus Torvalds } 39850eeca283SRobert Love 39861da177e4SLinus Torvalds return error; 39871da177e4SLinus Torvalds } 39884d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39891da177e4SLinus Torvalds 39901da177e4SLinus Torvalds /* 39911da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39921b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39931da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39941da177e4SLinus Torvalds * while waiting on the I/O. 39951da177e4SLinus Torvalds */ 3996da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39971da177e4SLinus Torvalds { 39982ad94ae6SAl Viro int error; 39991da177e4SLinus Torvalds struct dentry *dentry; 4000f5beed75SAl Viro struct path path; 4001f5beed75SAl Viro struct qstr last; 4002f5beed75SAl Viro int type; 40031da177e4SLinus Torvalds struct inode *inode = NULL; 4004b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 40055d18f813SJeff Layton unsigned int lookup_flags = 0; 40065d18f813SJeff Layton retry: 4007da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 400891a27b2aSJeff Layton if (IS_ERR(name)) 400991a27b2aSJeff Layton return PTR_ERR(name); 40102ad94ae6SAl Viro 40111da177e4SLinus Torvalds error = -EISDIR; 4012f5beed75SAl Viro if (type != LAST_NORM) 40131da177e4SLinus Torvalds goto exit1; 40140612d9fbSOGAWA Hirofumi 4015f5beed75SAl Viro error = mnt_want_write(path.mnt); 4016c30dabfeSJan Kara if (error) 4017c30dabfeSJan Kara goto exit1; 4018b21996e3SJ. Bruce Fields retry_deleg: 40195955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4020f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40211da177e4SLinus Torvalds error = PTR_ERR(dentry); 40221da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40231da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4024f5beed75SAl Viro if (last.name[last.len]) 402550338b88STörök Edwin goto slashes; 40261da177e4SLinus Torvalds inode = dentry->d_inode; 4027b18825a7SDavid Howells if (d_is_negative(dentry)) 4028e6bc45d6STheodore Ts'o goto slashes; 40297de9c6eeSAl Viro ihold(inode); 4030f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4031be6d3e56SKentaro Takeda if (error) 4032c30dabfeSJan Kara goto exit2; 4033f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40341da177e4SLinus Torvalds exit2: 40351da177e4SLinus Torvalds dput(dentry); 40361da177e4SLinus Torvalds } 40375955102cSAl Viro inode_unlock(path.dentry->d_inode); 40381da177e4SLinus Torvalds if (inode) 40391da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4040b21996e3SJ. Bruce Fields inode = NULL; 4041b21996e3SJ. Bruce Fields if (delegated_inode) { 40425a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4043b21996e3SJ. Bruce Fields if (!error) 4044b21996e3SJ. Bruce Fields goto retry_deleg; 4045b21996e3SJ. Bruce Fields } 4046f5beed75SAl Viro mnt_drop_write(path.mnt); 40471da177e4SLinus Torvalds exit1: 4048f5beed75SAl Viro path_put(&path); 40495d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40505d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40515d18f813SJeff Layton inode = NULL; 40525d18f813SJeff Layton goto retry; 40535d18f813SJeff Layton } 4054da2f1362SChristoph Hellwig putname(name); 40551da177e4SLinus Torvalds return error; 40561da177e4SLinus Torvalds 40571da177e4SLinus Torvalds slashes: 4058b18825a7SDavid Howells if (d_is_negative(dentry)) 4059b18825a7SDavid Howells error = -ENOENT; 406044b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4061b18825a7SDavid Howells error = -EISDIR; 4062b18825a7SDavid Howells else 4063b18825a7SDavid Howells error = -ENOTDIR; 40641da177e4SLinus Torvalds goto exit2; 40651da177e4SLinus Torvalds } 40661da177e4SLinus Torvalds 40672e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40685590ff0dSUlrich Drepper { 40695590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40705590ff0dSUlrich Drepper return -EINVAL; 40715590ff0dSUlrich Drepper 40725590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40735590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40745590ff0dSUlrich Drepper 4075da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40765590ff0dSUlrich Drepper } 40775590ff0dSUlrich Drepper 40783480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40795590ff0dSUlrich Drepper { 4080da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40815590ff0dSUlrich Drepper } 40825590ff0dSUlrich Drepper 4083db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40841da177e4SLinus Torvalds { 4085a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40861da177e4SLinus Torvalds 40871da177e4SLinus Torvalds if (error) 40881da177e4SLinus Torvalds return error; 40891da177e4SLinus Torvalds 4090acfa4380SAl Viro if (!dir->i_op->symlink) 40911da177e4SLinus Torvalds return -EPERM; 40921da177e4SLinus Torvalds 40931da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40941da177e4SLinus Torvalds if (error) 40951da177e4SLinus Torvalds return error; 40961da177e4SLinus Torvalds 40971da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4098a74574aaSStephen Smalley if (!error) 4099f38aa942SAmy Griffis fsnotify_create(dir, dentry); 41001da177e4SLinus Torvalds return error; 41011da177e4SLinus Torvalds } 41024d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 41031da177e4SLinus Torvalds 41042e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 41052e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 41061da177e4SLinus Torvalds { 41072ad94ae6SAl Viro int error; 410891a27b2aSJeff Layton struct filename *from; 41096902d925SDave Hansen struct dentry *dentry; 4110dae6ad8fSAl Viro struct path path; 4111f46d3567SJeff Layton unsigned int lookup_flags = 0; 41121da177e4SLinus Torvalds 41131da177e4SLinus Torvalds from = getname(oldname); 41141da177e4SLinus Torvalds if (IS_ERR(from)) 41151da177e4SLinus Torvalds return PTR_ERR(from); 4116f46d3567SJeff Layton retry: 4117f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41181da177e4SLinus Torvalds error = PTR_ERR(dentry); 41196902d925SDave Hansen if (IS_ERR(dentry)) 4120dae6ad8fSAl Viro goto out_putname; 41216902d925SDave Hansen 412291a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4123a8104a9fSAl Viro if (!error) 412491a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4125921a1650SAl Viro done_path_create(&path, dentry); 4126f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4127f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4128f46d3567SJeff Layton goto retry; 4129f46d3567SJeff Layton } 41306902d925SDave Hansen out_putname: 41311da177e4SLinus Torvalds putname(from); 41321da177e4SLinus Torvalds return error; 41331da177e4SLinus Torvalds } 41341da177e4SLinus Torvalds 41353480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41365590ff0dSUlrich Drepper { 41375590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41385590ff0dSUlrich Drepper } 41395590ff0dSUlrich Drepper 4140146a8595SJ. Bruce Fields /** 4141146a8595SJ. Bruce Fields * vfs_link - create a new link 4142146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4143146a8595SJ. Bruce Fields * @dir: new parent 4144146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4145146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4146146a8595SJ. Bruce Fields * 4147146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4148146a8595SJ. Bruce Fields * 4149146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4150146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4151146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4152146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4153146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4154146a8595SJ. Bruce Fields * 4155146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4156146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4157146a8595SJ. Bruce Fields * to be NFS exported. 4158146a8595SJ. Bruce Fields */ 4159146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41601da177e4SLinus Torvalds { 41611da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41628de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41631da177e4SLinus Torvalds int error; 41641da177e4SLinus Torvalds 41651da177e4SLinus Torvalds if (!inode) 41661da177e4SLinus Torvalds return -ENOENT; 41671da177e4SLinus Torvalds 4168a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41691da177e4SLinus Torvalds if (error) 41701da177e4SLinus Torvalds return error; 41711da177e4SLinus Torvalds 41721da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41731da177e4SLinus Torvalds return -EXDEV; 41741da177e4SLinus Torvalds 41751da177e4SLinus Torvalds /* 41761da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41771da177e4SLinus Torvalds */ 41781da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41791da177e4SLinus Torvalds return -EPERM; 41800bd23d09SEric W. Biederman /* 41810bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41820bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41830bd23d09SEric W. Biederman * the vfs. 41840bd23d09SEric W. Biederman */ 41850bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41860bd23d09SEric W. Biederman return -EPERM; 4187acfa4380SAl Viro if (!dir->i_op->link) 41881da177e4SLinus Torvalds return -EPERM; 41897e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41901da177e4SLinus Torvalds return -EPERM; 41911da177e4SLinus Torvalds 41921da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41931da177e4SLinus Torvalds if (error) 41941da177e4SLinus Torvalds return error; 41951da177e4SLinus Torvalds 41965955102cSAl Viro inode_lock(inode); 4197aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4198f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4199aae8a97dSAneesh Kumar K.V error = -ENOENT; 42008de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 42018de52778SAl Viro error = -EMLINK; 4202146a8595SJ. Bruce Fields else { 4203146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4204146a8595SJ. Bruce Fields if (!error) 42051da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4206146a8595SJ. Bruce Fields } 4207f4e0c30cSAl Viro 4208f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4209f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4210f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4211f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4212f4e0c30cSAl Viro } 42135955102cSAl Viro inode_unlock(inode); 4214e31e14ecSStephen Smalley if (!error) 42157e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42161da177e4SLinus Torvalds return error; 42171da177e4SLinus Torvalds } 42184d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42191da177e4SLinus Torvalds 42201da177e4SLinus Torvalds /* 42211da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42221da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42231da177e4SLinus Torvalds * newname. --KAB 42241da177e4SLinus Torvalds * 42251da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42261da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42271da177e4SLinus Torvalds * and other special files. --ADM 42281da177e4SLinus Torvalds */ 42292e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42302e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42311da177e4SLinus Torvalds { 42321da177e4SLinus Torvalds struct dentry *new_dentry; 4233dae6ad8fSAl Viro struct path old_path, new_path; 4234146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 423511a7b371SAneesh Kumar K.V int how = 0; 42361da177e4SLinus Torvalds int error; 42371da177e4SLinus Torvalds 423811a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4239c04030e1SUlrich Drepper return -EINVAL; 424011a7b371SAneesh Kumar K.V /* 4241f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4242f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4243f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 424411a7b371SAneesh Kumar K.V */ 4245f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4246f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4247f0cc6ffbSLinus Torvalds return -ENOENT; 424811a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4249f0cc6ffbSLinus Torvalds } 4250c04030e1SUlrich Drepper 425111a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 425211a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4253442e31caSJeff Layton retry: 425411a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42551da177e4SLinus Torvalds if (error) 42562ad94ae6SAl Viro return error; 42572ad94ae6SAl Viro 4258442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4259442e31caSJeff Layton (how & LOOKUP_REVAL)); 42601da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42616902d925SDave Hansen if (IS_ERR(new_dentry)) 4262dae6ad8fSAl Viro goto out; 4263dae6ad8fSAl Viro 4264dae6ad8fSAl Viro error = -EXDEV; 4265dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4266dae6ad8fSAl Viro goto out_dput; 4267800179c9SKees Cook error = may_linkat(&old_path); 4268800179c9SKees Cook if (unlikely(error)) 4269800179c9SKees Cook goto out_dput; 4270dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4271be6d3e56SKentaro Takeda if (error) 4272a8104a9fSAl Viro goto out_dput; 4273146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 427475c3f29dSDave Hansen out_dput: 4275921a1650SAl Viro done_path_create(&new_path, new_dentry); 4276146a8595SJ. Bruce Fields if (delegated_inode) { 4277146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4278d22e6338SOleg Drokin if (!error) { 4279d22e6338SOleg Drokin path_put(&old_path); 4280146a8595SJ. Bruce Fields goto retry; 4281146a8595SJ. Bruce Fields } 4282d22e6338SOleg Drokin } 4283442e31caSJeff Layton if (retry_estale(error, how)) { 4284d22e6338SOleg Drokin path_put(&old_path); 4285442e31caSJeff Layton how |= LOOKUP_REVAL; 4286442e31caSJeff Layton goto retry; 4287442e31caSJeff Layton } 42881da177e4SLinus Torvalds out: 42892d8f3038SAl Viro path_put(&old_path); 42901da177e4SLinus Torvalds 42911da177e4SLinus Torvalds return error; 42921da177e4SLinus Torvalds } 42931da177e4SLinus Torvalds 42943480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42955590ff0dSUlrich Drepper { 4296c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42975590ff0dSUlrich Drepper } 42985590ff0dSUlrich Drepper 4299bc27027aSMiklos Szeredi /** 4300bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4301bc27027aSMiklos Szeredi * @old_dir: parent of source 4302bc27027aSMiklos Szeredi * @old_dentry: source 4303bc27027aSMiklos Szeredi * @new_dir: parent of destination 4304bc27027aSMiklos Szeredi * @new_dentry: destination 4305bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4306520c8b16SMiklos Szeredi * @flags: rename flags 4307bc27027aSMiklos Szeredi * 4308bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4309bc27027aSMiklos Szeredi * 4310bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4311bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4312bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4313bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4314bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4315bc27027aSMiklos Szeredi * so. 4316bc27027aSMiklos Szeredi * 4317bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4318bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4319bc27027aSMiklos Szeredi * to be NFS exported. 4320bc27027aSMiklos Szeredi * 43211da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43221da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43231da177e4SLinus Torvalds * Problems: 43240117d427SMauro Carvalho Chehab * 4325d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43261da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43271da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4328a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43291da177e4SLinus Torvalds * story. 43306cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43316cedba89SJ. Bruce Fields * and source (if it is not a directory). 43321b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43331da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43341da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4335a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43361da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43371da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43381da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4339a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43401da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43411da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43421da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4343e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43441b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43451da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4346c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43471da177e4SLinus Torvalds * locking]. 43481da177e4SLinus Torvalds */ 43491da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43508e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4351520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43521da177e4SLinus Torvalds { 43531da177e4SLinus Torvalds int error; 4354bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4355bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4356bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4357da1ce067SMiklos Szeredi bool new_is_dir = false; 4358da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 435949d31c2fSAl Viro struct name_snapshot old_name; 43601da177e4SLinus Torvalds 43618d3e2936SMiklos Szeredi if (source == target) 43621da177e4SLinus Torvalds return 0; 43631da177e4SLinus Torvalds 43641da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43651da177e4SLinus Torvalds if (error) 43661da177e4SLinus Torvalds return error; 43671da177e4SLinus Torvalds 4368da1ce067SMiklos Szeredi if (!target) { 4369a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4370da1ce067SMiklos Szeredi } else { 4371da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4372da1ce067SMiklos Szeredi 4373da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43741da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4375da1ce067SMiklos Szeredi else 4376da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4377da1ce067SMiklos Szeredi } 43781da177e4SLinus Torvalds if (error) 43791da177e4SLinus Torvalds return error; 43801da177e4SLinus Torvalds 43812773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43821da177e4SLinus Torvalds return -EPERM; 43831da177e4SLinus Torvalds 4384bc27027aSMiklos Szeredi /* 4385bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4386bc27027aSMiklos Szeredi * we'll need to flip '..'. 4387bc27027aSMiklos Szeredi */ 4388da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4389da1ce067SMiklos Szeredi if (is_dir) { 4390bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4391bc27027aSMiklos Szeredi if (error) 4392bc27027aSMiklos Szeredi return error; 4393bc27027aSMiklos Szeredi } 4394da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4395da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4396da1ce067SMiklos Szeredi if (error) 4397da1ce067SMiklos Szeredi return error; 4398da1ce067SMiklos Szeredi } 4399da1ce067SMiklos Szeredi } 44000eeca283SRobert Love 44010b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 44020b3974ebSMiklos Szeredi flags); 4403bc27027aSMiklos Szeredi if (error) 4404bc27027aSMiklos Szeredi return error; 4405bc27027aSMiklos Szeredi 440649d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4407bc27027aSMiklos Szeredi dget(new_dentry); 4408da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4409bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4410bc27027aSMiklos Szeredi else if (target) 44115955102cSAl Viro inode_lock(target); 4412bc27027aSMiklos Szeredi 4413bc27027aSMiklos Szeredi error = -EBUSY; 44147af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4415bc27027aSMiklos Szeredi goto out; 4416bc27027aSMiklos Szeredi 4417da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4418bc27027aSMiklos Szeredi error = -EMLINK; 4419da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4420bc27027aSMiklos Szeredi goto out; 4421da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4422da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4423da1ce067SMiklos Szeredi goto out; 4424da1ce067SMiklos Szeredi } 4425da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4426bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4427da1ce067SMiklos Szeredi if (!is_dir) { 4428bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4429bc27027aSMiklos Szeredi if (error) 4430bc27027aSMiklos Szeredi goto out; 4431da1ce067SMiklos Szeredi } 4432da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4433bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4434bc27027aSMiklos Szeredi if (error) 4435bc27027aSMiklos Szeredi goto out; 4436bc27027aSMiklos Szeredi } 4437520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4438520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4439bc27027aSMiklos Szeredi if (error) 4440bc27027aSMiklos Szeredi goto out; 4441bc27027aSMiklos Szeredi 4442da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44431da177e4SLinus Torvalds if (is_dir) 4444bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4445bc27027aSMiklos Szeredi dont_mount(new_dentry); 44468ed936b5SEric W. Biederman detach_mounts(new_dentry); 4447bc27027aSMiklos Szeredi } 4448da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4449da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4450bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4451da1ce067SMiklos Szeredi else 4452da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4453da1ce067SMiklos Szeredi } 4454bc27027aSMiklos Szeredi out: 4455da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4456bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4457bc27027aSMiklos Szeredi else if (target) 44585955102cSAl Viro inode_unlock(target); 4459bc27027aSMiklos Szeredi dput(new_dentry); 4460da1ce067SMiklos Szeredi if (!error) { 446149d31c2fSAl Viro fsnotify_move(old_dir, new_dir, old_name.name, is_dir, 4462da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4463da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4464da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4465da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4466da1ce067SMiklos Szeredi } 4467da1ce067SMiklos Szeredi } 446849d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44690eeca283SRobert Love 44701da177e4SLinus Torvalds return error; 44711da177e4SLinus Torvalds } 44724d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44731da177e4SLinus Torvalds 4474520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4475520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44761da177e4SLinus Torvalds { 44771da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44781da177e4SLinus Torvalds struct dentry *trap; 4479f5beed75SAl Viro struct path old_path, new_path; 4480f5beed75SAl Viro struct qstr old_last, new_last; 4481f5beed75SAl Viro int old_type, new_type; 44828e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 448391a27b2aSJeff Layton struct filename *from; 448491a27b2aSJeff Layton struct filename *to; 4485f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4486c6a94284SJeff Layton bool should_retry = false; 44872ad94ae6SAl Viro int error; 4488520c8b16SMiklos Szeredi 44890d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4490da1ce067SMiklos Szeredi return -EINVAL; 4491da1ce067SMiklos Szeredi 44920d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44930d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4494520c8b16SMiklos Szeredi return -EINVAL; 4495520c8b16SMiklos Szeredi 44960d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44970d7a8555SMiklos Szeredi return -EPERM; 44980d7a8555SMiklos Szeredi 4499f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4500f5beed75SAl Viro target_flags = 0; 4501f5beed75SAl Viro 4502c6a94284SJeff Layton retry: 4503c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4504c1d4dd27SAl Viro &old_path, &old_last, &old_type); 450591a27b2aSJeff Layton if (IS_ERR(from)) { 450691a27b2aSJeff Layton error = PTR_ERR(from); 45071da177e4SLinus Torvalds goto exit; 450891a27b2aSJeff Layton } 45091da177e4SLinus Torvalds 4510c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4511c1d4dd27SAl Viro &new_path, &new_last, &new_type); 451291a27b2aSJeff Layton if (IS_ERR(to)) { 451391a27b2aSJeff Layton error = PTR_ERR(to); 45141da177e4SLinus Torvalds goto exit1; 451591a27b2aSJeff Layton } 45161da177e4SLinus Torvalds 45171da177e4SLinus Torvalds error = -EXDEV; 4518f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45191da177e4SLinus Torvalds goto exit2; 45201da177e4SLinus Torvalds 45211da177e4SLinus Torvalds error = -EBUSY; 4522f5beed75SAl Viro if (old_type != LAST_NORM) 45231da177e4SLinus Torvalds goto exit2; 45241da177e4SLinus Torvalds 45250a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45260a7c3937SMiklos Szeredi error = -EEXIST; 4527f5beed75SAl Viro if (new_type != LAST_NORM) 45281da177e4SLinus Torvalds goto exit2; 45291da177e4SLinus Torvalds 4530f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4531c30dabfeSJan Kara if (error) 4532c30dabfeSJan Kara goto exit2; 4533c30dabfeSJan Kara 45348e6d782cSJ. Bruce Fields retry_deleg: 4535f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45361da177e4SLinus Torvalds 4537f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45381da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45391da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45401da177e4SLinus Torvalds goto exit3; 45411da177e4SLinus Torvalds /* source must exist */ 45421da177e4SLinus Torvalds error = -ENOENT; 4543b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45441da177e4SLinus Torvalds goto exit4; 4545f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45461da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45471da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45481da177e4SLinus Torvalds goto exit4; 45490a7c3937SMiklos Szeredi error = -EEXIST; 45500a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45510a7c3937SMiklos Szeredi goto exit5; 4552da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4553da1ce067SMiklos Szeredi error = -ENOENT; 4554da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4555da1ce067SMiklos Szeredi goto exit5; 4556da1ce067SMiklos Szeredi 4557da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4558da1ce067SMiklos Szeredi error = -ENOTDIR; 4559f5beed75SAl Viro if (new_last.name[new_last.len]) 4560da1ce067SMiklos Szeredi goto exit5; 4561da1ce067SMiklos Szeredi } 4562da1ce067SMiklos Szeredi } 45630a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45640a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45650a7c3937SMiklos Szeredi error = -ENOTDIR; 4566f5beed75SAl Viro if (old_last.name[old_last.len]) 45670a7c3937SMiklos Szeredi goto exit5; 4568f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45690a7c3937SMiklos Szeredi goto exit5; 45700a7c3937SMiklos Szeredi } 45710a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45720a7c3937SMiklos Szeredi error = -EINVAL; 45730a7c3937SMiklos Szeredi if (old_dentry == trap) 45740a7c3937SMiklos Szeredi goto exit5; 45751da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4576da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45771da177e4SLinus Torvalds error = -ENOTEMPTY; 45781da177e4SLinus Torvalds if (new_dentry == trap) 45791da177e4SLinus Torvalds goto exit5; 45801da177e4SLinus Torvalds 4581f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4582f5beed75SAl Viro &new_path, new_dentry, flags); 4583be6d3e56SKentaro Takeda if (error) 4584c30dabfeSJan Kara goto exit5; 4585f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4586f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4587520c8b16SMiklos Szeredi &delegated_inode, flags); 45881da177e4SLinus Torvalds exit5: 45891da177e4SLinus Torvalds dput(new_dentry); 45901da177e4SLinus Torvalds exit4: 45911da177e4SLinus Torvalds dput(old_dentry); 45921da177e4SLinus Torvalds exit3: 4593f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45948e6d782cSJ. Bruce Fields if (delegated_inode) { 45958e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45968e6d782cSJ. Bruce Fields if (!error) 45978e6d782cSJ. Bruce Fields goto retry_deleg; 45988e6d782cSJ. Bruce Fields } 4599f5beed75SAl Viro mnt_drop_write(old_path.mnt); 46001da177e4SLinus Torvalds exit2: 4601c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4602c6a94284SJeff Layton should_retry = true; 4603f5beed75SAl Viro path_put(&new_path); 46042ad94ae6SAl Viro putname(to); 46051da177e4SLinus Torvalds exit1: 4606f5beed75SAl Viro path_put(&old_path); 46071da177e4SLinus Torvalds putname(from); 4608c6a94284SJeff Layton if (should_retry) { 4609c6a94284SJeff Layton should_retry = false; 4610c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4611c6a94284SJeff Layton goto retry; 4612c6a94284SJeff Layton } 46132ad94ae6SAl Viro exit: 46141da177e4SLinus Torvalds return error; 46151da177e4SLinus Torvalds } 46161da177e4SLinus Torvalds 4617520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4618520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4619520c8b16SMiklos Szeredi { 4620520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4621520c8b16SMiklos Szeredi } 4622520c8b16SMiklos Szeredi 4623a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46245590ff0dSUlrich Drepper { 4625520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46265590ff0dSUlrich Drepper } 46275590ff0dSUlrich Drepper 4628787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4629787fb6bcSMiklos Szeredi { 4630787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4631787fb6bcSMiklos Szeredi if (error) 4632787fb6bcSMiklos Szeredi return error; 4633787fb6bcSMiklos Szeredi 4634787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4635787fb6bcSMiklos Szeredi return -EPERM; 4636787fb6bcSMiklos Szeredi 4637787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4638787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4639787fb6bcSMiklos Szeredi } 4640787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4641787fb6bcSMiklos Szeredi 46425d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46431da177e4SLinus Torvalds { 46445d826c84SAl Viro int len = PTR_ERR(link); 46451da177e4SLinus Torvalds if (IS_ERR(link)) 46461da177e4SLinus Torvalds goto out; 46471da177e4SLinus Torvalds 46481da177e4SLinus Torvalds len = strlen(link); 46491da177e4SLinus Torvalds if (len > (unsigned) buflen) 46501da177e4SLinus Torvalds len = buflen; 46511da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46521da177e4SLinus Torvalds len = -EFAULT; 46531da177e4SLinus Torvalds out: 46541da177e4SLinus Torvalds return len; 46551da177e4SLinus Torvalds } 46561da177e4SLinus Torvalds 46571da177e4SLinus Torvalds /* 46581da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46596b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46606b255391SAl Viro * for any given inode is up to filesystem. 46611da177e4SLinus Torvalds */ 4662d16744ecSMiklos Szeredi static int generic_readlink(struct dentry *dentry, char __user *buffer, 4663d16744ecSMiklos Szeredi int buflen) 46641da177e4SLinus Torvalds { 4665fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46665f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46675f2c4179SAl Viro const char *link = inode->i_link; 4668694a1764SMarcin Slusarz int res; 4669cc314eefSLinus Torvalds 4670d4dee48bSAl Viro if (!link) { 4671fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4672680baacbSAl Viro if (IS_ERR(link)) 4673680baacbSAl Viro return PTR_ERR(link); 4674d4dee48bSAl Viro } 4675680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4676fceef393SAl Viro do_delayed_call(&done); 4677694a1764SMarcin Slusarz return res; 46781da177e4SLinus Torvalds } 46791da177e4SLinus Torvalds 4680d60874cdSMiklos Szeredi /** 4681fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4682fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4683fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4684fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4685fd4a0edfSMiklos Szeredi * 4686fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4687fd4a0edfSMiklos Szeredi * 4688fd4a0edfSMiklos Szeredi * Does not call security hook. 4689fd4a0edfSMiklos Szeredi */ 4690fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4691fd4a0edfSMiklos Szeredi { 4692fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4693fd4a0edfSMiklos Szeredi 469476fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 469576fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 469676fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 469776fca90eSMiklos Szeredi 469876fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4699fd4a0edfSMiklos Szeredi return -EINVAL; 4700fd4a0edfSMiklos Szeredi 470176fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 470276fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 470376fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 470476fca90eSMiklos Szeredi } 470576fca90eSMiklos Szeredi 470676fca90eSMiklos Szeredi return generic_readlink(dentry, buffer, buflen); 4707fd4a0edfSMiklos Szeredi } 4708fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 47091da177e4SLinus Torvalds 4710d60874cdSMiklos Szeredi /** 4711d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4712d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4713d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4714d60874cdSMiklos Szeredi * 4715d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4716d60874cdSMiklos Szeredi * 4717d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4718d60874cdSMiklos Szeredi * 4719d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4720d60874cdSMiklos Szeredi */ 4721d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4722d60874cdSMiklos Szeredi { 4723d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4724d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4725d60874cdSMiklos Szeredi 4726d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4727d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4728d60874cdSMiklos Szeredi if (!res) 4729d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4730d60874cdSMiklos Szeredi } 4731d60874cdSMiklos Szeredi return res; 4732d60874cdSMiklos Szeredi } 4733d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4734d60874cdSMiklos Szeredi 47351da177e4SLinus Torvalds /* get the link contents into pagecache */ 47366b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4737fceef393SAl Viro struct delayed_call *callback) 47381da177e4SLinus Torvalds { 4739ebd09abbSDuane Griffin char *kaddr; 47401da177e4SLinus Torvalds struct page *page; 47416b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47426b255391SAl Viro 4743d3883d4fSAl Viro if (!dentry) { 4744d3883d4fSAl Viro page = find_get_page(mapping, 0); 4745d3883d4fSAl Viro if (!page) 47466b255391SAl Viro return ERR_PTR(-ECHILD); 4747d3883d4fSAl Viro if (!PageUptodate(page)) { 4748d3883d4fSAl Viro put_page(page); 4749d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4750d3883d4fSAl Viro } 4751d3883d4fSAl Viro } else { 4752090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47531da177e4SLinus Torvalds if (IS_ERR(page)) 47546fe6900eSNick Piggin return (char*)page; 4755d3883d4fSAl Viro } 4756fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 475721fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 475821fc61c7SAl Viro kaddr = page_address(page); 47596b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4760ebd09abbSDuane Griffin return kaddr; 47611da177e4SLinus Torvalds } 47621da177e4SLinus Torvalds 47636b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47641da177e4SLinus Torvalds 4765fceef393SAl Viro void page_put_link(void *arg) 47661da177e4SLinus Torvalds { 4767fceef393SAl Viro put_page(arg); 47681da177e4SLinus Torvalds } 47694d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47701da177e4SLinus Torvalds 4771aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4772aa80deabSAl Viro { 4773fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47746b255391SAl Viro int res = readlink_copy(buffer, buflen, 47756b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4776fceef393SAl Viro &done)); 4777fceef393SAl Viro do_delayed_call(&done); 4778aa80deabSAl Viro return res; 4779aa80deabSAl Viro } 4780aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4781aa80deabSAl Viro 478254566b2cSNick Piggin /* 478354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 478454566b2cSNick Piggin */ 478554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47861da177e4SLinus Torvalds { 47871da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47880adb25d2SKirill Korotaev struct page *page; 4789afddba49SNick Piggin void *fsdata; 4790beb497abSDmitriy Monakhov int err; 4791c718a975STetsuo Handa unsigned int flags = 0; 479254566b2cSNick Piggin if (nofs) 479354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47941da177e4SLinus Torvalds 47957e53cac4SNeilBrown retry: 4796afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 479754566b2cSNick Piggin flags, &page, &fsdata); 47981da177e4SLinus Torvalds if (err) 4799afddba49SNick Piggin goto fail; 4800afddba49SNick Piggin 480121fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4802afddba49SNick Piggin 4803afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4804afddba49SNick Piggin page, fsdata); 48051da177e4SLinus Torvalds if (err < 0) 48061da177e4SLinus Torvalds goto fail; 4807afddba49SNick Piggin if (err < len-1) 4808afddba49SNick Piggin goto retry; 4809afddba49SNick Piggin 48101da177e4SLinus Torvalds mark_inode_dirty(inode); 48111da177e4SLinus Torvalds return 0; 48121da177e4SLinus Torvalds fail: 48131da177e4SLinus Torvalds return err; 48141da177e4SLinus Torvalds } 48154d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48161da177e4SLinus Torvalds 48170adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48180adb25d2SKirill Korotaev { 48190adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4820c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48210adb25d2SKirill Korotaev } 48224d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48230adb25d2SKirill Korotaev 482492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48256b255391SAl Viro .get_link = page_get_link, 48261da177e4SLinus Torvalds }; 48271da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4828