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) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 4949883d185SAl Viro unsigned seq, m_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 506fceef393SAl Viro struct inode *link_inode; 5079883d185SAl Viro unsigned root_seq; 5089883d185SAl Viro int dfd; 5093859a271SKees Cook } __randomize_layout; 5101f55a6ecSAl Viro 5119883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 512894bc8c4SAl Viro { 513756daf26SNeilBrown struct nameidata *old = current->nameidata; 514756daf26SNeilBrown p->stack = p->internal; 515c8a53ee5SAl Viro p->dfd = dfd; 516c8a53ee5SAl Viro p->name = name; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5189883d185SAl Viro p->saved = old; 519756daf26SNeilBrown current->nameidata = p; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 5229883d185SAl Viro static void restore_nameidata(void) 523894bc8c4SAl Viro { 5249883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529e1a63bbcSAl Viro if (now->stack != now->internal) 530756daf26SNeilBrown kfree(now->stack); 531894bc8c4SAl Viro } 532894bc8c4SAl Viro 533894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 534894bc8c4SAl Viro { 535bc40aee0SAl Viro struct saved *p; 536bc40aee0SAl Viro 537bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5386da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 539bc40aee0SAl Viro GFP_ATOMIC); 540bc40aee0SAl Viro if (unlikely(!p)) 541bc40aee0SAl Viro return -ECHILD; 542bc40aee0SAl Viro } else { 5436da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 544894bc8c4SAl Viro GFP_KERNEL); 545894bc8c4SAl Viro if (unlikely(!p)) 546894bc8c4SAl Viro return -ENOMEM; 547bc40aee0SAl Viro } 548894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 549894bc8c4SAl Viro nd->stack = p; 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro } 552894bc8c4SAl Viro 553397d425dSEric W. Biederman /** 554397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 555397d425dSEric W. Biederman * @path: nameidate to verify 556397d425dSEric W. Biederman * 557397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 558397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 559397d425dSEric W. Biederman */ 560397d425dSEric W. Biederman static bool path_connected(const struct path *path) 561397d425dSEric W. Biederman { 562397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 56395dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 564397d425dSEric W. Biederman 56595dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56695dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 567397d425dSEric W. Biederman return true; 568397d425dSEric W. Biederman 569397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 570397d425dSEric W. Biederman } 571397d425dSEric W. Biederman 572894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 573894bc8c4SAl Viro { 574da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 575894bc8c4SAl Viro return 0; 576894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 577894bc8c4SAl Viro return 0; 578894bc8c4SAl Viro return __nd_alloc_stack(nd); 579894bc8c4SAl Viro } 580894bc8c4SAl Viro 5817973387aSAl Viro static void drop_links(struct nameidata *nd) 5827973387aSAl Viro { 5837973387aSAl Viro int i = nd->depth; 5847973387aSAl Viro while (i--) { 5857973387aSAl Viro struct saved *last = nd->stack + i; 586fceef393SAl Viro do_delayed_call(&last->done); 587fceef393SAl Viro clear_delayed_call(&last->done); 5887973387aSAl Viro } 5897973387aSAl Viro } 5907973387aSAl Viro 5917973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5927973387aSAl Viro { 5937973387aSAl Viro drop_links(nd); 5947973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5957973387aSAl Viro int i; 5967973387aSAl Viro path_put(&nd->path); 5977973387aSAl Viro for (i = 0; i < nd->depth; i++) 5987973387aSAl Viro path_put(&nd->stack[i].link); 59984a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 600102b8af2SAl Viro path_put(&nd->root); 60184a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 602102b8af2SAl Viro } 6037973387aSAl Viro } else { 6047973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 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 642ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 643ee594bffSAl Viro { 644ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 645ee594bffSAl Viro return true; 64684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 647ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 648ee594bffSAl Viro } 649ee594bffSAl Viro 65019660af7SAl Viro /* 65131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 65519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 65619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 65819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 65931e6b01fSNick Piggin */ 66031e6b01fSNick Piggin 66131e6b01fSNick Piggin /** 66219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66319660af7SAl Viro * @nd: nameidata pathwalk data 66439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 66531e6b01fSNick Piggin * 6664675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6674675ac39SAl Viro * for ref-walk mode. 6684675ac39SAl Viro * Must be called from rcu-walk context. 6697973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6707973387aSAl Viro * terminate_walk(). 67131e6b01fSNick Piggin */ 6724675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 67331e6b01fSNick Piggin { 67431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 67531e6b01fSNick Piggin 67631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 677e5c832d5SLinus Torvalds 678e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6797973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6804675ac39SAl Viro goto out1; 68184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 68284a2bd39SAl Viro goto out; 683ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6844675ac39SAl Viro goto out; 6854675ac39SAl Viro rcu_read_unlock(); 6864675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6874675ac39SAl Viro return 0; 6884675ac39SAl Viro 68984a2bd39SAl Viro out1: 6904675ac39SAl Viro nd->path.mnt = NULL; 6914675ac39SAl Viro nd->path.dentry = NULL; 6924675ac39SAl Viro out: 6934675ac39SAl Viro rcu_read_unlock(); 6944675ac39SAl Viro return -ECHILD; 6954675ac39SAl Viro } 6964675ac39SAl Viro 6974675ac39SAl Viro /** 6984675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 6994675ac39SAl Viro * @nd: nameidata pathwalk data 7004675ac39SAl Viro * @dentry: child of nd->path.dentry 7014675ac39SAl Viro * @seq: seq number to check dentry against 7024675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7034675ac39SAl Viro * 7044675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7054675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7064675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7074675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7084675ac39SAl Viro * terminate_walk(). 7094675ac39SAl Viro */ 7104675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7114675ac39SAl Viro { 7124675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7134675ac39SAl Viro 7144675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7154675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7164675ac39SAl Viro goto out2; 7177973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7187973387aSAl Viro goto out2; 7194675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7207973387aSAl Viro goto out1; 72148a066e7SAl Viro 72215570086SLinus Torvalds /* 7234675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7244675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7254675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7264675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7274675ac39SAl Viro * know the parent must still be valid if the child sequence number is 72815570086SLinus Torvalds */ 7294675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 730e5c832d5SLinus Torvalds goto out; 73184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 73284a2bd39SAl Viro goto out_dput; 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 */ 73784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 73884a2bd39SAl Viro goto out_dput; 7398b61e74fSAl Viro rcu_read_unlock(); 74031e6b01fSNick Piggin return 0; 74119660af7SAl Viro 7427973387aSAl Viro out2: 7437973387aSAl Viro nd->path.mnt = NULL; 7447973387aSAl Viro out1: 7457973387aSAl Viro nd->path.dentry = NULL; 746e5c832d5SLinus Torvalds out: 7478b61e74fSAl Viro rcu_read_unlock(); 74884a2bd39SAl Viro return -ECHILD; 74984a2bd39SAl Viro out_dput: 75084a2bd39SAl Viro rcu_read_unlock(); 75184a2bd39SAl Viro dput(dentry); 75231e6b01fSNick Piggin return -ECHILD; 75331e6b01fSNick Piggin } 75431e6b01fSNick Piggin 7554ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 75634286d66SNick Piggin { 757a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7584ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 759a89f8337SAl Viro else 760a89f8337SAl Viro return 1; 76134286d66SNick Piggin } 76234286d66SNick Piggin 7639f1fafeeSAl Viro /** 7649f1fafeeSAl Viro * complete_walk - successful completion of path walk 7659f1fafeeSAl Viro * @nd: pointer nameidata 76639159de2SJeff Layton * 7679f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7689f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7699f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7709f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7719f1fafeeSAl Viro * need to drop nd->path. 77239159de2SJeff Layton */ 7739f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77439159de2SJeff Layton { 77516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 77639159de2SJeff Layton int status; 77739159de2SJeff Layton 7789f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7799f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7809f1fafeeSAl Viro nd->root.mnt = NULL; 7814675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 78248a066e7SAl Viro return -ECHILD; 78348a066e7SAl Viro } 7849f1fafeeSAl Viro 78516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 78639159de2SJeff Layton return 0; 78739159de2SJeff Layton 788ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 78916c2cd71SAl Viro return 0; 79016c2cd71SAl Viro 791ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79239159de2SJeff Layton if (status > 0) 79339159de2SJeff Layton return 0; 79439159de2SJeff Layton 79516c2cd71SAl Viro if (!status) 79639159de2SJeff Layton status = -ESTALE; 79716c2cd71SAl Viro 79839159de2SJeff Layton return status; 79939159de2SJeff Layton } 80039159de2SJeff Layton 80118d8c860SAl Viro static void set_root(struct nameidata *nd) 8022a737871SAl Viro { 80331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8049e6697e2SAl Viro 8059e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8068f47a016SAl Viro unsigned seq; 807c28cc364SNick Piggin 808c28cc364SNick Piggin do { 809c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81031e6b01fSNick Piggin nd->root = fs->root; 8118f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 812c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8139e6697e2SAl Viro } else { 8149e6697e2SAl Viro get_fs_root(fs, &nd->root); 81584a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8169e6697e2SAl Viro } 81731e6b01fSNick Piggin } 81831e6b01fSNick Piggin 8191d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 820051d3812SIan Kent { 821051d3812SIan Kent dput(path->dentry); 8224ac91378SJan Blunck if (path->mnt != nd->path.mnt) 823051d3812SIan Kent mntput(path->mnt); 824051d3812SIan Kent } 825051d3812SIan Kent 8267b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8277b9337aaSNick Piggin struct nameidata *nd) 828051d3812SIan Kent { 82931e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8304ac91378SJan Blunck dput(nd->path.dentry); 83131e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8324ac91378SJan Blunck mntput(nd->path.mnt); 8339a229683SHuang Shijie } 83431e6b01fSNick Piggin nd->path.mnt = path->mnt; 8354ac91378SJan Blunck nd->path.dentry = path->dentry; 836051d3812SIan Kent } 837051d3812SIan Kent 838248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 839248fb5b9SAl Viro { 840248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 841248fb5b9SAl Viro struct dentry *d; 842248fb5b9SAl Viro nd->path = nd->root; 843248fb5b9SAl Viro d = nd->path.dentry; 844248fb5b9SAl Viro nd->inode = d->d_inode; 845248fb5b9SAl Viro nd->seq = nd->root_seq; 846248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 847248fb5b9SAl Viro return -ECHILD; 848248fb5b9SAl Viro } else { 849248fb5b9SAl Viro path_put(&nd->path); 850248fb5b9SAl Viro nd->path = nd->root; 851248fb5b9SAl Viro path_get(&nd->path); 852248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 853248fb5b9SAl Viro } 854248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 855248fb5b9SAl Viro return 0; 856248fb5b9SAl Viro } 857248fb5b9SAl Viro 858b5fb63c1SChristoph Hellwig /* 8596b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 860b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 861b5fb63c1SChristoph Hellwig */ 8626e77137bSAl Viro void nd_jump_link(struct path *path) 863b5fb63c1SChristoph Hellwig { 8646e77137bSAl Viro struct nameidata *nd = current->nameidata; 865b5fb63c1SChristoph Hellwig path_put(&nd->path); 866b5fb63c1SChristoph Hellwig 867b5fb63c1SChristoph Hellwig nd->path = *path; 868b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 869b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 870b5fb63c1SChristoph Hellwig } 871b5fb63c1SChristoph Hellwig 872b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 873574197e0SAl Viro { 87421c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 875fceef393SAl Viro do_delayed_call(&last->done); 8766548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 877b9ff4429SAl Viro path_put(&last->link); 878574197e0SAl Viro } 879574197e0SAl Viro 880561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 881561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 88230aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 88330aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 884800179c9SKees Cook 885800179c9SKees Cook /** 886800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 88755852635SRandy Dunlap * @nd: nameidata pathwalk data 888800179c9SKees Cook * 889800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 890800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 891800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 892800179c9SKees Cook * processes from failing races against path names that may change out 893800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 894800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 895800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 896800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 897800179c9SKees Cook * 898800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 899800179c9SKees Cook */ 900fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 901800179c9SKees Cook { 902800179c9SKees Cook const struct inode *inode; 903800179c9SKees Cook const struct inode *parent; 9042d7f9e2aSSeth Forshee kuid_t puid; 905800179c9SKees Cook 906800179c9SKees Cook if (!sysctl_protected_symlinks) 907800179c9SKees Cook return 0; 908800179c9SKees Cook 909800179c9SKees Cook /* Allowed if owner and follower match. */ 910fceef393SAl Viro inode = nd->link_inode; 91181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 912800179c9SKees Cook return 0; 913800179c9SKees Cook 914800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 915aa65fa35SAl Viro parent = nd->inode; 916800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 917800179c9SKees Cook return 0; 918800179c9SKees Cook 919800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9202d7f9e2aSSeth Forshee puid = parent->i_uid; 9212d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 922800179c9SKees Cook return 0; 923800179c9SKees Cook 92431956502SAl Viro if (nd->flags & LOOKUP_RCU) 92531956502SAl Viro return -ECHILD; 92631956502SAl Viro 927ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 928245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 929800179c9SKees Cook return -EACCES; 930800179c9SKees Cook } 931800179c9SKees Cook 932800179c9SKees Cook /** 933800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 934800179c9SKees Cook * @inode: the source inode to hardlink from 935800179c9SKees Cook * 936800179c9SKees Cook * Return false if at least one of the following conditions: 937800179c9SKees Cook * - inode is not a regular file 938800179c9SKees Cook * - inode is setuid 939800179c9SKees Cook * - inode is setgid and group-exec 940800179c9SKees Cook * - access failure for read and write 941800179c9SKees Cook * 942800179c9SKees Cook * Otherwise returns true. 943800179c9SKees Cook */ 944800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 945800179c9SKees Cook { 946800179c9SKees Cook umode_t mode = inode->i_mode; 947800179c9SKees Cook 948800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 949800179c9SKees Cook if (!S_ISREG(mode)) 950800179c9SKees Cook return false; 951800179c9SKees Cook 952800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 953800179c9SKees Cook if (mode & S_ISUID) 954800179c9SKees Cook return false; 955800179c9SKees Cook 956800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 957800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 958800179c9SKees Cook return false; 959800179c9SKees Cook 960800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 961800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 962800179c9SKees Cook return false; 963800179c9SKees Cook 964800179c9SKees Cook return true; 965800179c9SKees Cook } 966800179c9SKees Cook 967800179c9SKees Cook /** 968800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 969800179c9SKees Cook * @link: the source to hardlink from 970800179c9SKees Cook * 971800179c9SKees Cook * Block hardlink when all of: 972800179c9SKees Cook * - sysctl_protected_hardlinks enabled 973800179c9SKees Cook * - fsuid does not match inode 974800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 975f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 976800179c9SKees Cook * 977800179c9SKees Cook * Returns 0 if successful, -ve on error. 978800179c9SKees Cook */ 979800179c9SKees Cook static int may_linkat(struct path *link) 980800179c9SKees Cook { 981593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 982593d1ce8SEric W. Biederman 983593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 984593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 985593d1ce8SEric W. Biederman return -EOVERFLOW; 986800179c9SKees Cook 987800179c9SKees Cook if (!sysctl_protected_hardlinks) 988800179c9SKees Cook return 0; 989800179c9SKees Cook 990800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 991800179c9SKees Cook * otherwise, it must be a safe source. 992800179c9SKees Cook */ 993cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 994800179c9SKees Cook return 0; 995800179c9SKees Cook 996245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 997800179c9SKees Cook return -EPERM; 998800179c9SKees Cook } 999800179c9SKees Cook 100030aba665SSalvatore Mesoraca /** 100130aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 100230aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 100330aba665SSalvatore Mesoraca * exist. 100430aba665SSalvatore Mesoraca * @dir: the sticky parent directory 100530aba665SSalvatore Mesoraca * @inode: the inode of the file to open 100630aba665SSalvatore Mesoraca * 100730aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 100830aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 100930aba665SSalvatore Mesoraca * - the file already exists 101030aba665SSalvatore Mesoraca * - we are in a sticky directory 101130aba665SSalvatore Mesoraca * - we don't own the file 101230aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 101330aba665SSalvatore Mesoraca * - the directory is world writable 101430aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 101530aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 101630aba665SSalvatore Mesoraca * be enough. 101730aba665SSalvatore Mesoraca * 101830aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 101930aba665SSalvatore Mesoraca */ 102030aba665SSalvatore Mesoraca static int may_create_in_sticky(struct dentry * const dir, 102130aba665SSalvatore Mesoraca struct inode * const inode) 102230aba665SSalvatore Mesoraca { 102330aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 102430aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 102530aba665SSalvatore Mesoraca likely(!(dir->d_inode->i_mode & S_ISVTX)) || 102630aba665SSalvatore Mesoraca uid_eq(inode->i_uid, dir->d_inode->i_uid) || 102730aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 102830aba665SSalvatore Mesoraca return 0; 102930aba665SSalvatore Mesoraca 103030aba665SSalvatore Mesoraca if (likely(dir->d_inode->i_mode & 0002) || 103130aba665SSalvatore Mesoraca (dir->d_inode->i_mode & 0020 && 103230aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 103330aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1034245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1035245d7369SKees Cook "sticky_create_fifo" : 1036245d7369SKees Cook "sticky_create_regular"; 1037245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 103830aba665SSalvatore Mesoraca return -EACCES; 103930aba665SSalvatore Mesoraca } 104030aba665SSalvatore Mesoraca return 0; 104130aba665SSalvatore Mesoraca } 104230aba665SSalvatore Mesoraca 10433b2e7f75SAl Viro static __always_inline 10443b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10451da177e4SLinus Torvalds { 1046ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10471cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1048fceef393SAl Viro struct inode *inode = nd->link_inode; 10496d7b5aaeSAl Viro int error; 10500a959df5SAl Viro const char *res; 10511da177e4SLinus Torvalds 10528fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10538fa9dd24SNeilBrown touch_atime(&last->link); 10548fa9dd24SNeilBrown cond_resched(); 1055c6718543SMiklos Szeredi } else if (atime_needs_update(&last->link, inode)) { 10564675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10578fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10588fa9dd24SNeilBrown touch_atime(&last->link); 10598fa9dd24SNeilBrown } 10608fa9dd24SNeilBrown 1061bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1062bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1063bda0be7aSNeilBrown if (unlikely(error)) 10646920a440SAl Viro return ERR_PTR(error); 106536f3b4f6SAl Viro 106686acdca1SAl Viro nd->last_type = LAST_BIND; 10674c4f7c19SEric Biggers res = READ_ONCE(inode->i_link); 1068d4dee48bSAl Viro if (!res) { 1069fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1070fceef393SAl Viro struct delayed_call *); 1071fceef393SAl Viro get = inode->i_op->get_link; 10728c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1073fceef393SAl Viro res = get(NULL, inode, &last->done); 10746b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10754675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10768c1b4566SAl Viro return ERR_PTR(-ECHILD); 1077fceef393SAl Viro res = get(dentry, inode, &last->done); 10788c1b4566SAl Viro } 10796b255391SAl Viro } else { 1080fceef393SAl Viro res = get(dentry, inode, &last->done); 10816b255391SAl Viro } 1082fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1083fab51e8aSAl Viro return res; 10840a959df5SAl Viro } 1085fab51e8aSAl Viro if (*res == '/') { 1086fab51e8aSAl Viro if (!nd->root.mnt) 1087fab51e8aSAl Viro set_root(nd); 1088248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1089fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1090fab51e8aSAl Viro while (unlikely(*++res == '/')) 1091fab51e8aSAl Viro ; 1092fab51e8aSAl Viro } 1093fab51e8aSAl Viro if (!*res) 1094fab51e8aSAl Viro res = NULL; 10950a959df5SAl Viro return res; 10960a959df5SAl Viro } 10976d7b5aaeSAl Viro 1098f015f126SDavid Howells /* 1099f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1100f015f126SDavid Howells * 1101f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1102f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1103f015f126SDavid Howells * Up is towards /. 1104f015f126SDavid Howells * 1105f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1106f015f126SDavid Howells * root. 1107f015f126SDavid Howells */ 1108bab77ebfSAl Viro int follow_up(struct path *path) 11091da177e4SLinus Torvalds { 11100714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11110714a533SAl Viro struct mount *parent; 11121da177e4SLinus Torvalds struct dentry *mountpoint; 111399b7db7bSNick Piggin 111448a066e7SAl Viro read_seqlock_excl(&mount_lock); 11150714a533SAl Viro parent = mnt->mnt_parent; 11163c0a6163SAl Viro if (parent == mnt) { 111748a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11181da177e4SLinus Torvalds return 0; 11191da177e4SLinus Torvalds } 11200714a533SAl Viro mntget(&parent->mnt); 1121a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 112248a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1123bab77ebfSAl Viro dput(path->dentry); 1124bab77ebfSAl Viro path->dentry = mountpoint; 1125bab77ebfSAl Viro mntput(path->mnt); 11260714a533SAl Viro path->mnt = &parent->mnt; 11271da177e4SLinus Torvalds return 1; 11281da177e4SLinus Torvalds } 11294d359507SAl Viro EXPORT_SYMBOL(follow_up); 11301da177e4SLinus Torvalds 1131b5c84bf6SNick Piggin /* 11329875cf80SDavid Howells * Perform an automount 11339875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11349875cf80SDavid Howells * were called with. 11351da177e4SLinus Torvalds */ 1136756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 11379875cf80SDavid Howells bool *need_mntput) 113831e6b01fSNick Piggin { 11399875cf80SDavid Howells struct vfsmount *mnt; 1140ea5b778aSDavid Howells int err; 11419875cf80SDavid Howells 11429875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11439875cf80SDavid Howells return -EREMOTE; 11449875cf80SDavid Howells 11450ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11460ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11470ec26fd0SMiklos Szeredi * the name. 11480ec26fd0SMiklos Szeredi * 11490ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11505a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11510ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11520ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11530ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11540ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11555a30d8a2SDavid Howells */ 1156756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11575d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11585d38f049SIan Kent path->dentry->d_inode) 11599875cf80SDavid Howells return -EISDIR; 11600ec26fd0SMiklos Szeredi 1161756daf26SNeilBrown nd->total_link_count++; 1162756daf26SNeilBrown if (nd->total_link_count >= 40) 11639875cf80SDavid Howells return -ELOOP; 11649875cf80SDavid Howells 11659875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11669875cf80SDavid Howells if (IS_ERR(mnt)) { 11679875cf80SDavid Howells /* 11689875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11699875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11709875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11719875cf80SDavid Howells * 11729875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11739875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11749875cf80SDavid Howells * the path is inaccessible and we should say so. 11759875cf80SDavid Howells */ 1176756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11779875cf80SDavid Howells return -EREMOTE; 11789875cf80SDavid Howells return PTR_ERR(mnt); 117931e6b01fSNick Piggin } 1180ea5b778aSDavid Howells 11819875cf80SDavid Howells if (!mnt) /* mount collision */ 11829875cf80SDavid Howells return 0; 11839875cf80SDavid Howells 11848aef1884SAl Viro if (!*need_mntput) { 11858aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11868aef1884SAl Viro mntget(path->mnt); 11878aef1884SAl Viro *need_mntput = true; 11888aef1884SAl Viro } 118919a167afSAl Viro err = finish_automount(mnt, path); 1190ea5b778aSDavid Howells 1191ea5b778aSDavid Howells switch (err) { 1192ea5b778aSDavid Howells case -EBUSY: 1193ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 119419a167afSAl Viro return 0; 1195ea5b778aSDavid Howells case 0: 11968aef1884SAl Viro path_put(path); 11979875cf80SDavid Howells path->mnt = mnt; 11989875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11999875cf80SDavid Howells return 0; 120019a167afSAl Viro default: 120119a167afSAl Viro return err; 12029875cf80SDavid Howells } 120319a167afSAl Viro 1204ea5b778aSDavid Howells } 12059875cf80SDavid Howells 12069875cf80SDavid Howells /* 12079875cf80SDavid Howells * Handle a dentry that is managed in some way. 1208cc53ce53SDavid Howells * - Flagged for transit management (autofs) 12099875cf80SDavid Howells * - Flagged as mountpoint 12109875cf80SDavid Howells * - Flagged as automount point 12119875cf80SDavid Howells * 12129875cf80SDavid Howells * This may only be called in refwalk mode. 1213d41efb52SAl Viro * On success path->dentry is known positive. 12149875cf80SDavid Howells * 12159875cf80SDavid Howells * Serialization is taken care of in namespace.c 12169875cf80SDavid Howells */ 1217756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 12189875cf80SDavid Howells { 12198aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 1220d41efb52SAl Viro unsigned flags; 12219875cf80SDavid Howells bool need_mntput = false; 12228aef1884SAl Viro int ret = 0; 12239875cf80SDavid Howells 12249875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 12259875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 12269875cf80SDavid Howells * the components of that value change under us */ 12272fa6b1e0SAl Viro while (flags = smp_load_acquire(&path->dentry->d_flags), 1228d41efb52SAl Viro unlikely(flags & DCACHE_MANAGED_DENTRY)) { 1229cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1230cc53ce53SDavid Howells * being held. */ 1231d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1232cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1233cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1234fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1235508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1236cc53ce53SDavid Howells if (ret < 0) 12378aef1884SAl Viro break; 1238cc53ce53SDavid Howells } 1239cc53ce53SDavid Howells 12409875cf80SDavid Howells /* Transit to a mounted filesystem. */ 1241d41efb52SAl Viro if (flags & DCACHE_MOUNTED) { 12429875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12439875cf80SDavid Howells if (mounted) { 12449875cf80SDavid Howells dput(path->dentry); 12459875cf80SDavid Howells if (need_mntput) 1246463ffb2eSAl Viro mntput(path->mnt); 1247463ffb2eSAl Viro path->mnt = mounted; 1248463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12499875cf80SDavid Howells need_mntput = true; 12509875cf80SDavid Howells continue; 1251463ffb2eSAl Viro } 1252463ffb2eSAl Viro 12539875cf80SDavid Howells /* Something is mounted on this dentry in another 12549875cf80SDavid Howells * namespace and/or whatever was mounted there in this 125548a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 125648a066e7SAl Viro * get it */ 12571da177e4SLinus Torvalds } 12589875cf80SDavid Howells 12599875cf80SDavid Howells /* Handle an automount point */ 1260d41efb52SAl Viro if (flags & DCACHE_NEED_AUTOMOUNT) { 1261756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12629875cf80SDavid Howells if (ret < 0) 12638aef1884SAl Viro break; 12649875cf80SDavid Howells continue; 12659875cf80SDavid Howells } 12669875cf80SDavid Howells 12679875cf80SDavid Howells /* We didn't change the current path point */ 12689875cf80SDavid Howells break; 12699875cf80SDavid Howells } 12708aef1884SAl Viro 12718aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12728aef1884SAl Viro mntput(path->mnt); 12738402752eSAl Viro if (need_mntput) 12748402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 1275d41efb52SAl Viro if (ret == -EISDIR || !ret) 1276d41efb52SAl Viro ret = 1; 1277d41efb52SAl Viro if (ret > 0 && unlikely(d_flags_negative(flags))) 1278d41efb52SAl Viro ret = -ENOENT; 12798402752eSAl Viro if (unlikely(ret < 0)) 12808402752eSAl Viro path_put_conditional(path, nd); 12818402752eSAl Viro return ret; 12821da177e4SLinus Torvalds } 12831da177e4SLinus Torvalds 1284cc53ce53SDavid Howells int follow_down_one(struct path *path) 12851da177e4SLinus Torvalds { 12861da177e4SLinus Torvalds struct vfsmount *mounted; 12871da177e4SLinus Torvalds 12881c755af4SAl Viro mounted = lookup_mnt(path); 12891da177e4SLinus Torvalds if (mounted) { 12909393bd07SAl Viro dput(path->dentry); 12919393bd07SAl Viro mntput(path->mnt); 12929393bd07SAl Viro path->mnt = mounted; 12939393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12941da177e4SLinus Torvalds return 1; 12951da177e4SLinus Torvalds } 12961da177e4SLinus Torvalds return 0; 12971da177e4SLinus Torvalds } 12984d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12991da177e4SLinus Torvalds 1300fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 130162a7375eSIan Kent { 1302fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1303fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 130462a7375eSIan Kent } 130562a7375eSIan Kent 13069875cf80SDavid Howells /* 1307287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1308287548e4SAl Viro * we meet a managed dentry that would need blocking. 13099875cf80SDavid Howells */ 13109875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1311254cf582SAl Viro struct inode **inode, unsigned *seqp) 13129875cf80SDavid Howells { 131362a7375eSIan Kent for (;;) { 1314c7105365SAl Viro struct mount *mounted; 131562a7375eSIan Kent /* 131662a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 131762a7375eSIan Kent * that wants to block transit. 131862a7375eSIan Kent */ 1319fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1320b8faf035SNeilBrown case -ECHILD: 1321b8faf035SNeilBrown default: 1322ab90911fSDavid Howells return false; 1323b8faf035SNeilBrown case -EISDIR: 1324b8faf035SNeilBrown return true; 1325b8faf035SNeilBrown case 0: 1326b8faf035SNeilBrown break; 1327b8faf035SNeilBrown } 132862a7375eSIan Kent 132962a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1330b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 133162a7375eSIan Kent 1332474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 13339875cf80SDavid Howells if (!mounted) 13349875cf80SDavid Howells break; 1335c7105365SAl Viro path->mnt = &mounted->mnt; 1336c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1337a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1338254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 133959430262SLinus Torvalds /* 134059430262SLinus Torvalds * Update the inode too. We don't need to re-check the 134159430262SLinus Torvalds * dentry sequence number here after this d_inode read, 134259430262SLinus Torvalds * because a mount-point is always pinned. 134359430262SLinus Torvalds */ 134459430262SLinus Torvalds *inode = path->dentry->d_inode; 13459875cf80SDavid Howells } 1346f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1347b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1348287548e4SAl Viro } 1349287548e4SAl Viro 135031e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 135131e6b01fSNick Piggin { 13524023bfc9SAl Viro struct inode *inode = nd->inode; 135331e6b01fSNick Piggin 135431e6b01fSNick Piggin while (1) { 1355aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 135631e6b01fSNick Piggin break; 135731e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 135831e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 135931e6b01fSNick Piggin struct dentry *parent = old->d_parent; 136031e6b01fSNick Piggin unsigned seq; 136131e6b01fSNick Piggin 13624023bfc9SAl Viro inode = parent->d_inode; 136331e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1364aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1365aed434adSAl Viro return -ECHILD; 136631e6b01fSNick Piggin nd->path.dentry = parent; 136731e6b01fSNick Piggin nd->seq = seq; 1368397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1369397d425dSEric W. Biederman return -ENOENT; 137031e6b01fSNick Piggin break; 1371aed434adSAl Viro } else { 1372aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1373aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1374aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1375aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1376aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1377aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1378aed434adSAl Viro return -ECHILD; 1379aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 138031e6b01fSNick Piggin break; 1381aed434adSAl Viro /* we know that mountpoint was pinned */ 1382aed434adSAl Viro nd->path.dentry = mountpoint; 1383aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1384aed434adSAl Viro inode = inode2; 1385aed434adSAl Viro nd->seq = seq; 138631e6b01fSNick Piggin } 1387aed434adSAl Viro } 1388aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1389b37199e6SAl Viro struct mount *mounted; 1390b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1391aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1392aed434adSAl Viro return -ECHILD; 1393b37199e6SAl Viro if (!mounted) 1394b37199e6SAl Viro break; 1395b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1396b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13974023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1398b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1399b37199e6SAl Viro } 14004023bfc9SAl Viro nd->inode = inode; 140131e6b01fSNick Piggin return 0; 140231e6b01fSNick Piggin } 140331e6b01fSNick Piggin 14049875cf80SDavid Howells /* 1405cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1406cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1407cc53ce53SDavid Howells * caller is permitted to proceed or not. 1408cc53ce53SDavid Howells */ 14097cc90cc3SAl Viro int follow_down(struct path *path) 1410cc53ce53SDavid Howells { 1411cc53ce53SDavid Howells unsigned managed; 1412cc53ce53SDavid Howells int ret; 1413cc53ce53SDavid Howells 14146aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1415cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1416cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1417cc53ce53SDavid Howells * being held. 1418cc53ce53SDavid Howells * 1419cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1420cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1421cc53ce53SDavid Howells * other than its daemon the right to mount on its 1422cc53ce53SDavid Howells * superstructure. 1423cc53ce53SDavid Howells * 1424cc53ce53SDavid Howells * The filesystem may sleep at this point. 1425cc53ce53SDavid Howells */ 1426cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1427cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1428cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1429fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1430cc53ce53SDavid Howells if (ret < 0) 1431cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1432cc53ce53SDavid Howells } 1433cc53ce53SDavid Howells 1434cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1435cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1436cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1437cc53ce53SDavid Howells if (!mounted) 1438cc53ce53SDavid Howells break; 1439cc53ce53SDavid Howells dput(path->dentry); 1440cc53ce53SDavid Howells mntput(path->mnt); 1441cc53ce53SDavid Howells path->mnt = mounted; 1442cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1443cc53ce53SDavid Howells continue; 1444cc53ce53SDavid Howells } 1445cc53ce53SDavid Howells 1446cc53ce53SDavid Howells /* Don't handle automount points here */ 1447cc53ce53SDavid Howells break; 1448cc53ce53SDavid Howells } 1449cc53ce53SDavid Howells return 0; 1450cc53ce53SDavid Howells } 14514d359507SAl Viro EXPORT_SYMBOL(follow_down); 1452cc53ce53SDavid Howells 1453cc53ce53SDavid Howells /* 14549875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14559875cf80SDavid Howells */ 14569875cf80SDavid Howells static void follow_mount(struct path *path) 14579875cf80SDavid Howells { 14589875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14599875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14609875cf80SDavid Howells if (!mounted) 14619875cf80SDavid Howells break; 14629875cf80SDavid Howells dput(path->dentry); 14639875cf80SDavid Howells mntput(path->mnt); 14649875cf80SDavid Howells path->mnt = mounted; 14659875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14669875cf80SDavid Howells } 14679875cf80SDavid Howells } 14689875cf80SDavid Howells 1469eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1470eedf265aSEric W. Biederman { 1471eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1472eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1473eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1474eedf265aSEric W. Biederman dput(old); 1475eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1476eedf265aSEric W. Biederman return -ENOENT; 1477eedf265aSEric W. Biederman return 0; 1478eedf265aSEric W. Biederman } 1479eedf265aSEric W. Biederman 1480397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14811da177e4SLinus Torvalds { 14821da177e4SLinus Torvalds while(1) { 1483030c7e0bSDanilo Krummrich if (path_equal(&nd->path, &nd->root)) 14841da177e4SLinus Torvalds break; 14854ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1486eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1487eedf265aSEric W. Biederman if (ret) 1488eedf265aSEric W. Biederman return ret; 14891da177e4SLinus Torvalds break; 14901da177e4SLinus Torvalds } 14913088dd70SAl Viro if (!follow_up(&nd->path)) 14921da177e4SLinus Torvalds break; 14931da177e4SLinus Torvalds } 149479ed0226SAl Viro follow_mount(&nd->path); 149531e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1496397d425dSEric W. Biederman return 0; 14971da177e4SLinus Torvalds } 14981da177e4SLinus Torvalds 14991da177e4SLinus Torvalds /* 1500f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1501f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1502baa03890SNick Piggin */ 1503e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1504e3c13928SAl Viro struct dentry *dir, 15056c51e513SAl Viro unsigned int flags) 1506baa03890SNick Piggin { 1507a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1508bad61189SMiklos Szeredi if (dentry) { 1509a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1510bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 151174ff0ffcSAl Viro if (!error) 15125542aa2fSEric W. Biederman d_invalidate(dentry); 1513bad61189SMiklos Szeredi dput(dentry); 151474ff0ffcSAl Viro return ERR_PTR(error); 1515bad61189SMiklos Szeredi } 1516bad61189SMiklos Szeredi } 1517baa03890SNick Piggin return dentry; 1518baa03890SNick Piggin } 1519baa03890SNick Piggin 1520baa03890SNick Piggin /* 1521a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1522a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1523a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1524a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1525a03ece5fSAl Viro * at all. 152644396f4bSJosef Bacik */ 1527a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1528a03ece5fSAl Viro struct dentry *base, unsigned int flags) 152944396f4bSJosef Bacik { 1530a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 153144396f4bSJosef Bacik struct dentry *old; 1532a03ece5fSAl Viro struct inode *dir = base->d_inode; 1533a03ece5fSAl Viro 1534a03ece5fSAl Viro if (dentry) 1535a03ece5fSAl Viro return dentry; 153644396f4bSJosef Bacik 153744396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1538a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 153944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1540a03ece5fSAl Viro 1541a03ece5fSAl Viro dentry = d_alloc(base, name); 1542a03ece5fSAl Viro if (unlikely(!dentry)) 1543a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 154444396f4bSJosef Bacik 154572bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 154644396f4bSJosef Bacik if (unlikely(old)) { 154744396f4bSJosef Bacik dput(dentry); 154844396f4bSJosef Bacik dentry = old; 154944396f4bSJosef Bacik } 155044396f4bSJosef Bacik return dentry; 155144396f4bSJosef Bacik } 155244396f4bSJosef Bacik 1553e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1554254cf582SAl Viro struct path *path, struct inode **inode, 1555254cf582SAl Viro unsigned *seqp) 15561da177e4SLinus Torvalds { 15574ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 155831e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15595a18fff2SAl Viro int status = 1; 15609875cf80SDavid Howells int err; 15619875cf80SDavid Howells 15623cac260aSAl Viro /* 1563b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15645d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15655d0f49c1SAl Viro * going to fall back to non-racy lookup. 1566b04f784eSNick Piggin */ 156731e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 156831e6b01fSNick Piggin unsigned seq; 1569766c4cbfSAl Viro bool negative; 1570da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15715d0f49c1SAl Viro if (unlikely(!dentry)) { 15724675ac39SAl Viro if (unlazy_walk(nd)) 15735d0f49c1SAl Viro return -ECHILD; 1574e9742b53SAl Viro return 0; 15755d0f49c1SAl Viro } 15765a18fff2SAl Viro 157712f8ad4bSLinus Torvalds /* 157812f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 157912f8ad4bSLinus Torvalds * the dentry name information from lookup. 158012f8ad4bSLinus Torvalds */ 158163afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1582766c4cbfSAl Viro negative = d_is_negative(dentry); 15835d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 158412f8ad4bSLinus Torvalds return -ECHILD; 158512f8ad4bSLinus Torvalds 158612f8ad4bSLinus Torvalds /* 158712f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 158812f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 158912f8ad4bSLinus Torvalds * 159012f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 159112f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 159212f8ad4bSLinus Torvalds */ 15935d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 159431e6b01fSNick Piggin return -ECHILD; 15955a18fff2SAl Viro 1596254cf582SAl Viro *seqp = seq; 15974ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1598209a7fb2SAl Viro if (likely(status > 0)) { 1599daf3761cSTrond Myklebust /* 1600daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1601daf3761cSTrond Myklebust * case that drops it. 1602daf3761cSTrond Myklebust */ 16035d0f49c1SAl Viro if (unlikely(negative)) 1604daf3761cSTrond Myklebust return -ENOENT; 160531e6b01fSNick Piggin path->mnt = mnt; 160631e6b01fSNick Piggin path->dentry = dentry; 1607254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1608e9742b53SAl Viro return 1; 16095d0f49c1SAl Viro } 16104675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1611254cf582SAl Viro return -ECHILD; 1612209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1613209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1614209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 16155a18fff2SAl Viro } else { 1616e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 161781e6f520SAl Viro if (unlikely(!dentry)) 1618e9742b53SAl Viro return 0; 16194ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 16205d0f49c1SAl Viro } 16215a18fff2SAl Viro if (unlikely(status <= 0)) { 1622e9742b53SAl Viro if (!status) 16235d0f49c1SAl Viro d_invalidate(dentry); 16245a18fff2SAl Viro dput(dentry); 16255a18fff2SAl Viro return status; 16265a18fff2SAl Viro } 16275d0f49c1SAl Viro 16281da177e4SLinus Torvalds path->mnt = mnt; 16291da177e4SLinus Torvalds path->dentry = dentry; 1630756daf26SNeilBrown err = follow_managed(path, nd); 1631e9742b53SAl Viro if (likely(err > 0)) 163263afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 16338402752eSAl Viro return err; 1634697f514dSMiklos Szeredi } 1635697f514dSMiklos Szeredi 1636697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 163788d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1638e3c13928SAl Viro struct dentry *dir, 1639e3c13928SAl Viro unsigned int flags) 1640697f514dSMiklos Szeredi { 164188d8331aSAl Viro struct dentry *dentry, *old; 16421936386eSAl Viro struct inode *inode = dir->d_inode; 1643d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16441936386eSAl Viro 16451936386eSAl Viro /* Don't go there if it's already dead */ 164694bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 164788d8331aSAl Viro return ERR_PTR(-ENOENT); 164894bdd655SAl Viro again: 1649d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 165094bdd655SAl Viro if (IS_ERR(dentry)) 165188d8331aSAl Viro return dentry; 165294bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1653949a852eSAl Viro int error = d_revalidate(dentry, flags); 1654949a852eSAl Viro if (unlikely(error <= 0)) { 165594bdd655SAl Viro if (!error) { 1656949a852eSAl Viro d_invalidate(dentry); 1657949a852eSAl Viro dput(dentry); 165894bdd655SAl Viro goto again; 165994bdd655SAl Viro } 166094bdd655SAl Viro dput(dentry); 1661949a852eSAl Viro dentry = ERR_PTR(error); 1662949a852eSAl Viro } 166394bdd655SAl Viro } else { 16641936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 166585c7f810SAl Viro d_lookup_done(dentry); 16661936386eSAl Viro if (unlikely(old)) { 16671936386eSAl Viro dput(dentry); 16681936386eSAl Viro dentry = old; 1669949a852eSAl Viro } 1670949a852eSAl Viro } 1671e3c13928SAl Viro return dentry; 16721da177e4SLinus Torvalds } 16731da177e4SLinus Torvalds 167488d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 167588d8331aSAl Viro struct dentry *dir, 167688d8331aSAl Viro unsigned int flags) 167788d8331aSAl Viro { 167888d8331aSAl Viro struct inode *inode = dir->d_inode; 167988d8331aSAl Viro struct dentry *res; 168088d8331aSAl Viro inode_lock_shared(inode); 168188d8331aSAl Viro res = __lookup_slow(name, dir, flags); 168288d8331aSAl Viro inode_unlock_shared(inode); 168388d8331aSAl Viro return res; 168488d8331aSAl Viro } 168588d8331aSAl Viro 168652094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 168752094c8aSAl Viro { 168852094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16894ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 169052094c8aSAl Viro if (err != -ECHILD) 169152094c8aSAl Viro return err; 16924675ac39SAl Viro if (unlazy_walk(nd)) 169352094c8aSAl Viro return -ECHILD; 169452094c8aSAl Viro } 16954ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 169652094c8aSAl Viro } 169752094c8aSAl Viro 16989856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16999856fa1bSAl Viro { 17009856fa1bSAl Viro if (type == LAST_DOTDOT) { 17019e6697e2SAl Viro if (!nd->root.mnt) 17029e6697e2SAl Viro set_root(nd); 17039856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 170470291aecSAl Viro return follow_dotdot_rcu(nd); 17059856fa1bSAl Viro } else 1706397d425dSEric W. Biederman return follow_dotdot(nd); 17079856fa1bSAl Viro } 17089856fa1bSAl Viro return 0; 17099856fa1bSAl Viro } 17109856fa1bSAl Viro 1711181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1712181548c0SAl Viro struct inode *inode, unsigned seq) 1713d63ff28fSAl Viro { 1714626de996SAl Viro int error; 17151cf2665bSAl Viro struct saved *last; 1716756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1717626de996SAl Viro path_to_nameidata(link, nd); 1718626de996SAl Viro return -ELOOP; 1719626de996SAl Viro } 1720bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1721cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1722cd179f44SAl Viro mntget(link->mnt); 17237973387aSAl Viro } 1724626de996SAl Viro error = nd_alloc_stack(nd); 1725626de996SAl Viro if (unlikely(error)) { 1726bc40aee0SAl Viro if (error == -ECHILD) { 1727ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1728ad1633a1SAl Viro drop_links(nd); 1729ad1633a1SAl Viro nd->depth = 0; 1730ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1731ad1633a1SAl Viro nd->path.mnt = NULL; 1732ad1633a1SAl Viro nd->path.dentry = NULL; 1733ad1633a1SAl Viro rcu_read_unlock(); 17344675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1735bc40aee0SAl Viro error = nd_alloc_stack(nd); 1736bc40aee0SAl Viro } 1737bc40aee0SAl Viro if (error) { 1738cd179f44SAl Viro path_put(link); 1739626de996SAl Viro return error; 1740626de996SAl Viro } 1741bc40aee0SAl Viro } 1742626de996SAl Viro 1743ab104923SAl Viro last = nd->stack + nd->depth++; 17441cf2665bSAl Viro last->link = *link; 1745fceef393SAl Viro clear_delayed_call(&last->done); 1746fceef393SAl Viro nd->link_inode = inode; 17470450b2d1SAl Viro last->seq = seq; 1748d63ff28fSAl Viro return 1; 1749d63ff28fSAl Viro } 1750d63ff28fSAl Viro 17518f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 175231d66bcdSAl Viro 17533ddcd056SLinus Torvalds /* 17543ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17553ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17563ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17573ddcd056SLinus Torvalds * for the common case. 17583ddcd056SLinus Torvalds */ 17598f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17608f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17613ddcd056SLinus Torvalds { 176231d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 176331d66bcdSAl Viro put_link(nd); 17648f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17658f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17668f64fb1cSAl Viro /* not a symlink or should not follow */ 17678f64fb1cSAl Viro path_to_nameidata(path, nd); 17688f64fb1cSAl Viro nd->inode = inode; 17698f64fb1cSAl Viro nd->seq = seq; 1770d63ff28fSAl Viro return 0; 17718f64fb1cSAl Viro } 1772a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1773a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17748f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1775a7f77542SAl Viro return -ECHILD; 1776a7f77542SAl Viro } 17778f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17783ddcd056SLinus Torvalds } 17793ddcd056SLinus Torvalds 17804693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1781ce57dfc1SAl Viro { 1782caa85634SAl Viro struct path path; 1783ce57dfc1SAl Viro struct inode *inode; 1784254cf582SAl Viro unsigned seq; 1785ce57dfc1SAl Viro int err; 1786ce57dfc1SAl Viro /* 1787ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1788ce57dfc1SAl Viro * to be able to know about the current root directory and 1789ce57dfc1SAl Viro * parent relationships. 1790ce57dfc1SAl Viro */ 17914693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17924693a547SAl Viro err = handle_dots(nd, nd->last_type); 17931c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17944693a547SAl Viro put_link(nd); 17954693a547SAl Viro return err; 17964693a547SAl Viro } 1797254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1798e9742b53SAl Viro if (unlikely(err <= 0)) { 1799697f514dSMiklos Szeredi if (err < 0) 1800f0a9ba70SAl Viro return err; 1801e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1802e3c13928SAl Viro nd->flags); 1803e3c13928SAl Viro if (IS_ERR(path.dentry)) 1804e3c13928SAl Viro return PTR_ERR(path.dentry); 18057500c38aSAl Viro 1806e3c13928SAl Viro path.mnt = nd->path.mnt; 1807e3c13928SAl Viro err = follow_managed(&path, nd); 1808e3c13928SAl Viro if (unlikely(err < 0)) 1809f0a9ba70SAl Viro return err; 1810697f514dSMiklos Szeredi 1811254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1812d4565649SAl Viro inode = d_backing_inode(path.dentry); 1813766c4cbfSAl Viro } 1814697f514dSMiklos Szeredi 18158f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1816ce57dfc1SAl Viro } 1817ce57dfc1SAl Viro 18181da177e4SLinus Torvalds /* 1819bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1820bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1821bfcfaa77SLinus Torvalds * 1822bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1823bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1824bfcfaa77SLinus Torvalds * fast. 1825bfcfaa77SLinus Torvalds * 1826bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1827bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1828bfcfaa77SLinus Torvalds * crossing operation. 1829bfcfaa77SLinus Torvalds * 1830bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1831bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1832bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1833bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1834bfcfaa77SLinus Torvalds */ 1835bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1836bfcfaa77SLinus Torvalds 1837f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1838bfcfaa77SLinus Torvalds 1839468a9428SGeorge Spelvin #ifdef HASH_MIX 1840bfcfaa77SLinus Torvalds 1841468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1842468a9428SGeorge Spelvin 1843468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18442a18da7aSGeorge Spelvin /* 18452a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18462a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18472a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18482a18da7aSGeorge Spelvin * and no temporaries. 18492a18da7aSGeorge Spelvin * 18502a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18512a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18522a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18532a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18542a18da7aSGeorge Spelvin * 18552a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18562a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18572a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18582a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18592a18da7aSGeorge Spelvin * 18602a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18612a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18622a18da7aSGeorge Spelvin * toggling any given output bit. 18632a18da7aSGeorge Spelvin * 18642a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18652a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18662a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18672a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18682a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18692a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18702a18da7aSGeorge Spelvin * Perfect: 8192 258048 18712a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18722a18da7aSGeorge Spelvin */ 18732a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18742a18da7aSGeorge Spelvin ( x ^= (a), \ 18752a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18762a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18772a18da7aSGeorge Spelvin y *= 9 ) 1878bfcfaa77SLinus Torvalds 18790fed3ac8SGeorge Spelvin /* 18802a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18812a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18822a18da7aSGeorge Spelvin * work done before the hash value is used. 18830fed3ac8SGeorge Spelvin */ 18842a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18850fed3ac8SGeorge Spelvin { 18862a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18872a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18882a18da7aSGeorge Spelvin return y >> 32; 18890fed3ac8SGeorge Spelvin } 18900fed3ac8SGeorge Spelvin 1891bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1892bfcfaa77SLinus Torvalds 18932a18da7aSGeorge Spelvin /* 18942a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18952a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18962a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18972a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18982a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18992a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19002a18da7aSGeorge Spelvin * Perfect: 2048 31744 19012a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19022a18da7aSGeorge Spelvin */ 19032a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19042a18da7aSGeorge Spelvin ( x ^= (a), \ 19052a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19062a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19072a18da7aSGeorge Spelvin y *= 9 ) 1908bfcfaa77SLinus Torvalds 19092a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19100fed3ac8SGeorge Spelvin { 19112a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19122a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19130fed3ac8SGeorge Spelvin } 19140fed3ac8SGeorge Spelvin 1915bfcfaa77SLinus Torvalds #endif 1916bfcfaa77SLinus Torvalds 19172a18da7aSGeorge Spelvin /* 19182a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19192a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19202a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19212a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19222a18da7aSGeorge Spelvin * finds the delimiter after the name. 19232a18da7aSGeorge Spelvin */ 19248387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1925bfcfaa77SLinus Torvalds { 19268387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1927bfcfaa77SLinus Torvalds 1928bfcfaa77SLinus Torvalds for (;;) { 1929fcfd2fbfSGeorge Spelvin if (!len) 1930fcfd2fbfSGeorge Spelvin goto done; 1931e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1932bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1933bfcfaa77SLinus Torvalds break; 19342a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1935bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1936bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1937bfcfaa77SLinus Torvalds } 19382a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1939bfcfaa77SLinus Torvalds done: 19402a18da7aSGeorge Spelvin return fold_hash(x, y); 1941bfcfaa77SLinus Torvalds } 1942bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1943bfcfaa77SLinus Torvalds 1944fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19458387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1946fcfd2fbfSGeorge Spelvin { 19478387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19488387ff25SLinus Torvalds unsigned long adata, mask, len; 1949fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1950fcfd2fbfSGeorge Spelvin 19518387ff25SLinus Torvalds len = 0; 19528387ff25SLinus Torvalds goto inside; 19538387ff25SLinus Torvalds 1954fcfd2fbfSGeorge Spelvin do { 19552a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1956fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19578387ff25SLinus Torvalds inside: 1958fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1959fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1960fcfd2fbfSGeorge Spelvin 1961fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1962fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19632a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1964fcfd2fbfSGeorge Spelvin 19652a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1966fcfd2fbfSGeorge Spelvin } 1967fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1968fcfd2fbfSGeorge Spelvin 1969bfcfaa77SLinus Torvalds /* 1970bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1971d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1972bfcfaa77SLinus Torvalds */ 19738387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1974bfcfaa77SLinus Torvalds { 19758387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19768387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 197736126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1978bfcfaa77SLinus Torvalds 19798387ff25SLinus Torvalds len = 0; 19808387ff25SLinus Torvalds goto inside; 19818387ff25SLinus Torvalds 1982bfcfaa77SLinus Torvalds do { 19832a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1984bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19858387ff25SLinus Torvalds inside: 1986e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 198736126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 198836126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1989bfcfaa77SLinus Torvalds 199036126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 199136126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 199236126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19932a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 199436126f8fSLinus Torvalds 19952a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1996bfcfaa77SLinus Torvalds } 1997bfcfaa77SLinus Torvalds 19982a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1999bfcfaa77SLinus Torvalds 2000fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20018387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20020145acc2SLinus Torvalds { 20038387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20040145acc2SLinus Torvalds while (len--) 2005fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20060145acc2SLinus Torvalds return end_name_hash(hash); 20070145acc2SLinus Torvalds } 2008ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20090145acc2SLinus Torvalds 2010fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20118387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2012fcfd2fbfSGeorge Spelvin { 20138387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2014fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2015fcfd2fbfSGeorge Spelvin 2016fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2017e0ab7af9SGeorge Spelvin while (c) { 2018fcfd2fbfSGeorge Spelvin len++; 2019fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2020fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2021e0ab7af9SGeorge Spelvin } 2022fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2023fcfd2fbfSGeorge Spelvin } 2024f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2025fcfd2fbfSGeorge Spelvin 20263ddcd056SLinus Torvalds /* 2027200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2028200e9ef7SLinus Torvalds * one character. 2029200e9ef7SLinus Torvalds */ 20308387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2031200e9ef7SLinus Torvalds { 20328387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2033200e9ef7SLinus Torvalds unsigned long len = 0, c; 2034200e9ef7SLinus Torvalds 2035200e9ef7SLinus Torvalds c = (unsigned char)*name; 2036200e9ef7SLinus Torvalds do { 2037200e9ef7SLinus Torvalds len++; 2038200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2039200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2040200e9ef7SLinus Torvalds } while (c && c != '/'); 2041d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2042200e9ef7SLinus Torvalds } 2043200e9ef7SLinus Torvalds 2044bfcfaa77SLinus Torvalds #endif 2045bfcfaa77SLinus Torvalds 2046200e9ef7SLinus Torvalds /* 20471da177e4SLinus Torvalds * Name resolution. 2048ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2049ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20501da177e4SLinus Torvalds * 2051ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2052ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20531da177e4SLinus Torvalds */ 20546de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20551da177e4SLinus Torvalds { 20561da177e4SLinus Torvalds int err; 20571da177e4SLinus Torvalds 20589b5858e9SAl Viro if (IS_ERR(name)) 20599b5858e9SAl Viro return PTR_ERR(name); 20601da177e4SLinus Torvalds while (*name=='/') 20611da177e4SLinus Torvalds name++; 20621da177e4SLinus Torvalds if (!*name) 20639e18f10aSAl Viro return 0; 20641da177e4SLinus Torvalds 20651da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20661da177e4SLinus Torvalds for(;;) { 2067d6bb3e90SLinus Torvalds u64 hash_len; 2068fe479a58SAl Viro int type; 20691da177e4SLinus Torvalds 207052094c8aSAl Viro err = may_lookup(nd); 20711da177e4SLinus Torvalds if (err) 20723595e234SAl Viro return err; 20731da177e4SLinus Torvalds 20748387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20751da177e4SLinus Torvalds 2076fe479a58SAl Viro type = LAST_NORM; 2077d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2078fe479a58SAl Viro case 2: 2079200e9ef7SLinus Torvalds if (name[1] == '.') { 2080fe479a58SAl Viro type = LAST_DOTDOT; 208116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 208216c2cd71SAl Viro } 2083fe479a58SAl Viro break; 2084fe479a58SAl Viro case 1: 2085fe479a58SAl Viro type = LAST_DOT; 2086fe479a58SAl Viro } 20875a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20885a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 208916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20905a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2091a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2092da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20935a202bcdSAl Viro if (err < 0) 20943595e234SAl Viro return err; 2095d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2096d6bb3e90SLinus Torvalds name = this.name; 20975a202bcdSAl Viro } 20985a202bcdSAl Viro } 2099fe479a58SAl Viro 2100d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2101d6bb3e90SLinus Torvalds nd->last.name = name; 21025f4a6a69SAl Viro nd->last_type = type; 21035f4a6a69SAl Viro 2104d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2105d6bb3e90SLinus Torvalds if (!*name) 2106bdf6cbf1SAl Viro goto OK; 2107200e9ef7SLinus Torvalds /* 2108200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2109200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2110200e9ef7SLinus Torvalds */ 2111200e9ef7SLinus Torvalds do { 2112d6bb3e90SLinus Torvalds name++; 2113d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21148620c238SAl Viro if (unlikely(!*name)) { 21158620c238SAl Viro OK: 2116368ee9baSAl Viro /* pathname body, done */ 21178620c238SAl Viro if (!nd->depth) 21188620c238SAl Viro return 0; 21198620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2120368ee9baSAl Viro /* trailing symlink, done */ 21218620c238SAl Viro if (!name) 21228620c238SAl Viro return 0; 21238620c238SAl Viro /* last component of nested symlink */ 21248f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 21251c4ff1a8SAl Viro } else { 21261c4ff1a8SAl Viro /* not the last component */ 21278f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 21288620c238SAl Viro } 2129ce57dfc1SAl Viro if (err < 0) 21303595e234SAl Viro return err; 2131fe479a58SAl Viro 2132ce57dfc1SAl Viro if (err) { 2133626de996SAl Viro const char *s = get_link(nd); 21345a460275SAl Viro 2135a1c83681SViresh Kumar if (IS_ERR(s)) 21363595e234SAl Viro return PTR_ERR(s); 2137172a39a0SAl Viro err = 0; 213812b09578SAl Viro if (unlikely(!s)) { 213912b09578SAl Viro /* jumped */ 2140b9ff4429SAl Viro put_link(nd); 214112b09578SAl Viro } else { 2142071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 214332cd7468SAl Viro name = s; 21449e18f10aSAl Viro continue; 214548c8b0c5SAl Viro } 214631e6b01fSNick Piggin } 214797242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 214897242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21494675ac39SAl Viro if (unlazy_walk(nd)) 215097242f99SAl Viro return -ECHILD; 215197242f99SAl Viro } 21523595e234SAl Viro return -ENOTDIR; 21535f4a6a69SAl Viro } 2154ce57dfc1SAl Viro } 215597242f99SAl Viro } 21561da177e4SLinus Torvalds 2157edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2158c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 215931e6b01fSNick Piggin { 2160c8a53ee5SAl Viro const char *s = nd->name->name; 216131e6b01fSNick Piggin 2162c0eb027eSLinus Torvalds if (!*s) 2163c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2164edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2165edc2b1daSAl Viro rcu_read_lock(); 2166c0eb027eSLinus Torvalds 216731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2168980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 216931e6b01fSNick Piggin nd->depth = 0; 21705b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2171b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2172b18825a7SDavid Howells struct inode *inode = root->d_inode; 217393893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2174368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21755b6ca027SAl Viro nd->path = nd->root; 21765b6ca027SAl Viro nd->inode = inode; 21775b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21785b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21798f47a016SAl Viro nd->root_seq = nd->seq; 218048a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21815b6ca027SAl Viro } else { 21825b6ca027SAl Viro path_get(&nd->path); 21835b6ca027SAl Viro } 2184368ee9baSAl Viro return s; 21855b6ca027SAl Viro } 21865b6ca027SAl Viro 218731e6b01fSNick Piggin nd->root.mnt = NULL; 2188248fb5b9SAl Viro nd->path.mnt = NULL; 2189248fb5b9SAl Viro nd->path.dentry = NULL; 219031e6b01fSNick Piggin 219148a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2192fd2f7cb5SAl Viro if (*s == '/') { 2193e41f7d4eSAl Viro set_root(nd); 2194248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2195ef55d917SAl Viro return s; 2196ef55d917SAl Viro return ERR_PTR(-ECHILD); 2197c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2198e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 219931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2200c28cc364SNick Piggin unsigned seq; 220131e6b01fSNick Piggin 2202c28cc364SNick Piggin do { 2203c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 220431e6b01fSNick Piggin nd->path = fs->pwd; 2205ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2206c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2207c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2208e41f7d4eSAl Viro } else { 2209e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2210ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2211e41f7d4eSAl Viro } 2212ef55d917SAl Viro return s; 221331e6b01fSNick Piggin } else { 2214582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2215c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 221631e6b01fSNick Piggin struct dentry *dentry; 221731e6b01fSNick Piggin 22182903ff01SAl Viro if (!f.file) 2219368ee9baSAl Viro return ERR_PTR(-EBADF); 222031e6b01fSNick Piggin 22212903ff01SAl Viro dentry = f.file->f_path.dentry; 222231e6b01fSNick Piggin 2223edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22242903ff01SAl Viro fdput(f); 2225368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2226f52e0c11SAl Viro } 22272903ff01SAl Viro 22282903ff01SAl Viro nd->path = f.file->f_path; 2229e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 223034a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 223134a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22325590ff0dSUlrich Drepper } else { 22332903ff01SAl Viro path_get(&nd->path); 223434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22351da177e4SLinus Torvalds } 223634a26b99SAl Viro fdput(f); 2237368ee9baSAl Viro return s; 2238e41f7d4eSAl Viro } 22399b4a9b14SAl Viro } 22409b4a9b14SAl Viro 22413bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 224295fa25d9SAl Viro { 224395fa25d9SAl Viro const char *s; 2244fec2fa24SAl Viro int error = may_follow_link(nd); 2245deb106c6SAl Viro if (unlikely(error)) 22463bdba28bSAl Viro return ERR_PTR(error); 224795fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2248fab51e8aSAl Viro nd->stack[0].name = NULL; 22493b2e7f75SAl Viro s = get_link(nd); 2250deb106c6SAl Viro return s ? s : ""; 225195fa25d9SAl Viro } 225295fa25d9SAl Viro 2253caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2254bd92d7feSAl Viro { 2255bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2256bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2257bd92d7feSAl Viro 2258bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22591c4ff1a8SAl Viro return walk_component(nd, 0); 2260bd92d7feSAl Viro } 2261bd92d7feSAl Viro 22624f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22634f757f3cSAl Viro { 22644f757f3cSAl Viro struct path path = nd->path; 22654f757f3cSAl Viro struct inode *inode = nd->inode; 22664f757f3cSAl Viro unsigned seq = nd->seq; 22674f757f3cSAl Viro int err; 22684f757f3cSAl Viro 22694f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22704f757f3cSAl Viro /* 22714f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22724f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22734f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22744f757f3cSAl Viro */ 22754f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22764f757f3cSAl Viro return -ECHILD; 22774f757f3cSAl Viro } else { 22784f757f3cSAl Viro dget(path.dentry); 22794f757f3cSAl Viro err = follow_managed(&path, nd); 22804f757f3cSAl Viro if (unlikely(err < 0)) 22814f757f3cSAl Viro return err; 22824f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22834f757f3cSAl Viro seq = 0; 22844f757f3cSAl Viro } 22854f757f3cSAl Viro path_to_nameidata(&path, nd); 22864f757f3cSAl Viro nd->inode = inode; 22874f757f3cSAl Viro nd->seq = seq; 22884f757f3cSAl Viro return 0; 22894f757f3cSAl Viro } 22904f757f3cSAl Viro 22919b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2292c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22939b4a9b14SAl Viro { 2294c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2295bd92d7feSAl Viro int err; 229631e6b01fSNick Piggin 22979b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 22984f757f3cSAl Viro err = handle_lookup_down(nd); 22995f336e72SAl Viro if (unlikely(err < 0)) 23005f336e72SAl Viro s = ERR_PTR(err); 23014f757f3cSAl Viro } 23024f757f3cSAl Viro 23033bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 23043bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 23053bdba28bSAl Viro s = trailing_symlink(nd); 2306bd92d7feSAl Viro } 23079f1fafeeSAl Viro if (!err) 23089f1fafeeSAl Viro err = complete_walk(nd); 2309bd92d7feSAl Viro 2310deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2311deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2312bd23a539SAl Viro err = -ENOTDIR; 2313625b6d10SAl Viro if (!err) { 2314625b6d10SAl Viro *path = nd->path; 2315625b6d10SAl Viro nd->path.mnt = NULL; 2316625b6d10SAl Viro nd->path.dentry = NULL; 2317625b6d10SAl Viro } 2318deb106c6SAl Viro terminate_walk(nd); 2319bd92d7feSAl Viro return err; 232031e6b01fSNick Piggin } 232131e6b01fSNick Piggin 232231d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23239ad1aaa6SAl Viro struct path *path, struct path *root) 2324873f1eedSJeff Layton { 2325894bc8c4SAl Viro int retval; 23269883d185SAl Viro struct nameidata nd; 2327abc9f5beSAl Viro if (IS_ERR(name)) 2328abc9f5beSAl Viro return PTR_ERR(name); 23299ad1aaa6SAl Viro if (unlikely(root)) { 23309ad1aaa6SAl Viro nd.root = *root; 23319ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23329ad1aaa6SAl Viro } 23339883d185SAl Viro set_nameidata(&nd, dfd, name); 2334c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2335873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2336c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2337873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2338c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2339873f1eedSJeff Layton 2340873f1eedSJeff Layton if (likely(!retval)) 2341ff0ebee2SAl Viro audit_inode(name, path->dentry, 0); 23429883d185SAl Viro restore_nameidata(); 2343e4bd1c1aSAl Viro putname(name); 2344873f1eedSJeff Layton return retval; 2345873f1eedSJeff Layton } 2346873f1eedSJeff Layton 23478bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2348c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2349391172c4SAl Viro struct path *parent) 23508bcb77faSAl Viro { 2351c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23529b5858e9SAl Viro int err = link_path_walk(s, nd); 23538bcb77faSAl Viro if (!err) 23548bcb77faSAl Viro err = complete_walk(nd); 2355391172c4SAl Viro if (!err) { 2356391172c4SAl Viro *parent = nd->path; 2357391172c4SAl Viro nd->path.mnt = NULL; 2358391172c4SAl Viro nd->path.dentry = NULL; 2359391172c4SAl Viro } 2360deb106c6SAl Viro terminate_walk(nd); 23618bcb77faSAl Viro return err; 23628bcb77faSAl Viro } 23638bcb77faSAl Viro 23645c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2365391172c4SAl Viro unsigned int flags, struct path *parent, 2366391172c4SAl Viro struct qstr *last, int *type) 23678bcb77faSAl Viro { 23688bcb77faSAl Viro int retval; 23699883d185SAl Viro struct nameidata nd; 23708bcb77faSAl Viro 23715c31b6ceSAl Viro if (IS_ERR(name)) 23725c31b6ceSAl Viro return name; 23739883d185SAl Viro set_nameidata(&nd, dfd, name); 2374c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23758bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2376c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23778bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2378c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2379391172c4SAl Viro if (likely(!retval)) { 2380391172c4SAl Viro *last = nd.last; 2381391172c4SAl Viro *type = nd.last_type; 2382c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 23835c31b6ceSAl Viro } else { 23845c31b6ceSAl Viro putname(name); 23855c31b6ceSAl Viro name = ERR_PTR(retval); 2386391172c4SAl Viro } 23879883d185SAl Viro restore_nameidata(); 23885c31b6ceSAl Viro return name; 23898bcb77faSAl Viro } 23908bcb77faSAl Viro 239179714f72SAl Viro /* does lookup, returns the object with parent locked */ 239279714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23935590ff0dSUlrich Drepper { 23945c31b6ceSAl Viro struct filename *filename; 23955c31b6ceSAl Viro struct dentry *d; 2396391172c4SAl Viro struct qstr last; 2397391172c4SAl Viro int type; 239851689104SPaul Moore 23995c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24005c31b6ceSAl Viro &last, &type); 240151689104SPaul Moore if (IS_ERR(filename)) 240251689104SPaul Moore return ERR_CAST(filename); 24035c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2404391172c4SAl Viro path_put(path); 24055c31b6ceSAl Viro putname(filename); 24065c31b6ceSAl Viro return ERR_PTR(-EINVAL); 240779714f72SAl Viro } 24085955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2409391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 241079714f72SAl Viro if (IS_ERR(d)) { 24115955102cSAl Viro inode_unlock(path->dentry->d_inode); 2412391172c4SAl Viro path_put(path); 241379714f72SAl Viro } 241451689104SPaul Moore putname(filename); 241579714f72SAl Viro return d; 24165590ff0dSUlrich Drepper } 24175590ff0dSUlrich Drepper 2418d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2419d1811465SAl Viro { 2420abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2421abc9f5beSAl Viro flags, path, NULL); 2422d1811465SAl Viro } 24234d359507SAl Viro EXPORT_SYMBOL(kern_path); 2424d1811465SAl Viro 242516f18200SJosef 'Jeff' Sipek /** 242616f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 242716f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 242816f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 242916f18200SJosef 'Jeff' Sipek * @name: pointer to file name 243016f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2431e0a01249SAl Viro * @path: pointer to struct path to fill 243216f18200SJosef 'Jeff' Sipek */ 243316f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 243416f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2435e0a01249SAl Viro struct path *path) 243616f18200SJosef 'Jeff' Sipek { 24379ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24389ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2439abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2440abc9f5beSAl Viro flags , path, &root); 244116f18200SJosef 'Jeff' Sipek } 24424d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 244316f18200SJosef 'Jeff' Sipek 24443c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24453c95f0dcSAl Viro int len, struct qstr *this) 24463c95f0dcSAl Viro { 24473c95f0dcSAl Viro this->name = name; 24483c95f0dcSAl Viro this->len = len; 24493c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24503c95f0dcSAl Viro if (!len) 24513c95f0dcSAl Viro return -EACCES; 24523c95f0dcSAl Viro 24533c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24543c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24553c95f0dcSAl Viro return -EACCES; 24563c95f0dcSAl Viro } 24573c95f0dcSAl Viro 24583c95f0dcSAl Viro while (len--) { 24593c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24603c95f0dcSAl Viro if (c == '/' || c == '\0') 24613c95f0dcSAl Viro return -EACCES; 24623c95f0dcSAl Viro } 24633c95f0dcSAl Viro /* 24643c95f0dcSAl Viro * See if the low-level filesystem might want 24653c95f0dcSAl Viro * to use its own hash.. 24663c95f0dcSAl Viro */ 24673c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24683c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24693c95f0dcSAl Viro if (err < 0) 24703c95f0dcSAl Viro return err; 24713c95f0dcSAl Viro } 24723c95f0dcSAl Viro 24733c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24743c95f0dcSAl Viro } 24753c95f0dcSAl Viro 2476eead1911SChristoph Hellwig /** 24770da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 24780da0b7fdSDavid Howells * @name: pathname component to lookup 24790da0b7fdSDavid Howells * @base: base directory to lookup from 24800da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 24810da0b7fdSDavid Howells * 24820da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 24830da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 24840da0b7fdSDavid Howells * 24850da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 24860da0b7fdSDavid Howells * not be called by generic code. 24870da0b7fdSDavid Howells * 24880da0b7fdSDavid Howells * The caller must hold base->i_mutex. 24890da0b7fdSDavid Howells */ 24900da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 24910da0b7fdSDavid Howells { 24920da0b7fdSDavid Howells struct qstr this; 24930da0b7fdSDavid Howells int err; 24940da0b7fdSDavid Howells 24950da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24960da0b7fdSDavid Howells 24970da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 24980da0b7fdSDavid Howells if (err) 24990da0b7fdSDavid Howells return ERR_PTR(err); 25000da0b7fdSDavid Howells 25010da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25020da0b7fdSDavid Howells } 25030da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25040da0b7fdSDavid Howells 25050da0b7fdSDavid Howells /** 2506a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2507eead1911SChristoph Hellwig * @name: pathname component to lookup 2508eead1911SChristoph Hellwig * @base: base directory to lookup from 2509eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2510eead1911SChristoph Hellwig * 2511a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25129e7543e9SAl Viro * not be called by generic code. 2513bbddca8eSNeilBrown * 2514bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2515eead1911SChristoph Hellwig */ 2516057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2517057f6c01SJames Morris { 25188613a209SAl Viro struct dentry *dentry; 2519057f6c01SJames Morris struct qstr this; 2520cda309deSMiklos Szeredi int err; 2521057f6c01SJames Morris 25225955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25232f9092e1SDavid Woodhouse 25243c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2525cda309deSMiklos Szeredi if (err) 2526cda309deSMiklos Szeredi return ERR_PTR(err); 2527cda309deSMiklos Szeredi 25288613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25298613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2530057f6c01SJames Morris } 25314d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2532057f6c01SJames Morris 2533bbddca8eSNeilBrown /** 2534bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2535bbddca8eSNeilBrown * @name: pathname component to lookup 2536bbddca8eSNeilBrown * @base: base directory to lookup from 2537bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2538bbddca8eSNeilBrown * 2539bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2540bbddca8eSNeilBrown * not be called by generic code. 2541bbddca8eSNeilBrown * 2542bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2543bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2544bbddca8eSNeilBrown */ 2545bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2546bbddca8eSNeilBrown struct dentry *base, int len) 2547bbddca8eSNeilBrown { 2548bbddca8eSNeilBrown struct qstr this; 2549bbddca8eSNeilBrown int err; 255020d00ee8SLinus Torvalds struct dentry *ret; 2551bbddca8eSNeilBrown 25523c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2553bbddca8eSNeilBrown if (err) 2554bbddca8eSNeilBrown return ERR_PTR(err); 2555bbddca8eSNeilBrown 255620d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 255720d00ee8SLinus Torvalds if (!ret) 255820d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 255920d00ee8SLinus Torvalds return ret; 2560bbddca8eSNeilBrown } 2561bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2562bbddca8eSNeilBrown 25636c2d4798SAl Viro /* 25646c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 25656c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 25666c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 25676c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 25686c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 25696c2d4798SAl Viro * this one avoids such problems. 25706c2d4798SAl Viro */ 25716c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 25726c2d4798SAl Viro struct dentry *base, int len) 25736c2d4798SAl Viro { 25746c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 25752fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 25766c2d4798SAl Viro dput(ret); 25776c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 25786c2d4798SAl Viro } 25796c2d4798SAl Viro return ret; 25806c2d4798SAl Viro } 25816c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 25826c2d4798SAl Viro 2583eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2584eedf265aSEric W. Biederman int path_pts(struct path *path) 2585eedf265aSEric W. Biederman { 2586eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2587eedf265aSEric W. Biederman * the input path. 2588eedf265aSEric W. Biederman */ 2589eedf265aSEric W. Biederman struct dentry *child, *parent; 2590eedf265aSEric W. Biederman struct qstr this; 2591eedf265aSEric W. Biederman int ret; 2592eedf265aSEric W. Biederman 2593eedf265aSEric W. Biederman ret = path_parent_directory(path); 2594eedf265aSEric W. Biederman if (ret) 2595eedf265aSEric W. Biederman return ret; 2596eedf265aSEric W. Biederman 2597eedf265aSEric W. Biederman parent = path->dentry; 2598eedf265aSEric W. Biederman this.name = "pts"; 2599eedf265aSEric W. Biederman this.len = 3; 2600eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2601eedf265aSEric W. Biederman if (!child) 2602eedf265aSEric W. Biederman return -ENOENT; 2603eedf265aSEric W. Biederman 2604eedf265aSEric W. Biederman path->dentry = child; 2605eedf265aSEric W. Biederman dput(parent); 2606eedf265aSEric W. Biederman follow_mount(path); 2607eedf265aSEric W. Biederman return 0; 2608eedf265aSEric W. Biederman } 2609eedf265aSEric W. Biederman #endif 2610eedf265aSEric W. Biederman 26111fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26121fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26131da177e4SLinus Torvalds { 2614abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2615abc9f5beSAl Viro flags, path, NULL); 26161da177e4SLinus Torvalds } 2617b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26181fa1e7f6SAndy Whitcroft 26198033426eSJeff Layton /** 2620197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26212a78b857SMasanari Iida * @nd: lookup context 26228033426eSJeff Layton * @flags: lookup flags 2623c8a53ee5SAl Viro * @path: pointer to container for result 26248033426eSJeff Layton * 26258033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2626606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26278033426eSJeff Layton */ 26288033426eSJeff Layton static int 2629c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26308033426eSJeff Layton { 2631c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2632368ee9baSAl Viro int err; 26339b5858e9SAl Viro 26343bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2635c64cd6e3SAl Viro (err = lookup_last(nd)) > 0) { 26363bdba28bSAl Viro s = trailing_symlink(nd); 26373bdba28bSAl Viro } 2638c64cd6e3SAl Viro if (!err && (nd->flags & LOOKUP_RCU)) 2639c64cd6e3SAl Viro err = unlazy_walk(nd); 2640c64cd6e3SAl Viro if (!err) 2641c64cd6e3SAl Viro err = handle_lookup_down(nd); 2642ba8f4613SAl Viro if (!err) { 2643ba8f4613SAl Viro *path = nd->path; 2644ba8f4613SAl Viro nd->path.mnt = NULL; 2645ba8f4613SAl Viro nd->path.dentry = NULL; 2646ba8f4613SAl Viro } 2647deb106c6SAl Viro terminate_walk(nd); 26488033426eSJeff Layton return err; 26498033426eSJeff Layton } 26508033426eSJeff Layton 26512d864651SAl Viro static int 2652668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26532d864651SAl Viro unsigned int flags) 26542d864651SAl Viro { 26559883d185SAl Viro struct nameidata nd; 2656cbaab2dbSAl Viro int error; 2657668696dcSAl Viro if (IS_ERR(name)) 2658668696dcSAl Viro return PTR_ERR(name); 26599883d185SAl Viro set_nameidata(&nd, dfd, name); 2660c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26612d864651SAl Viro if (unlikely(error == -ECHILD)) 2662c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26632d864651SAl Viro if (unlikely(error == -ESTALE)) 2664c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26652d864651SAl Viro if (likely(!error)) 2666c9b07eabSAl Viro audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); 26679883d185SAl Viro restore_nameidata(); 2668668696dcSAl Viro putname(name); 26692d864651SAl Viro return error; 26702d864651SAl Viro } 26712d864651SAl Viro 26728033426eSJeff Layton /** 2673197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26748033426eSJeff Layton * @dfd: directory file descriptor 26758033426eSJeff Layton * @name: pathname from userland 26768033426eSJeff Layton * @flags: lookup flags 26778033426eSJeff Layton * @path: pointer to container to hold result 26788033426eSJeff Layton * 26798033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26808033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26818033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26828033426eSJeff Layton * and avoid revalidating the last component. 26838033426eSJeff Layton * 26848033426eSJeff Layton * Returns 0 and populates "path" on success. 26858033426eSJeff Layton */ 26868033426eSJeff Layton int 2687197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26888033426eSJeff Layton struct path *path) 26898033426eSJeff Layton { 2690cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26918033426eSJeff Layton } 26928033426eSJeff Layton 26932d864651SAl Viro int 26942d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 26952d864651SAl Viro unsigned int flags) 26962d864651SAl Viro { 2697cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 26982d864651SAl Viro } 26992d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27002d864651SAl Viro 2701cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27021da177e4SLinus Torvalds { 27038e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2704da9592edSDavid Howells 27058e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27061da177e4SLinus Torvalds return 0; 27078e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27081da177e4SLinus Torvalds return 0; 270923adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27101da177e4SLinus Torvalds } 2711cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27121da177e4SLinus Torvalds 27131da177e4SLinus Torvalds /* 27141da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27151da177e4SLinus Torvalds * whether the type of victim is right. 27161da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27171da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27181da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27191da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27201da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27211da177e4SLinus Torvalds * a. be owner of dir, or 27221da177e4SLinus Torvalds * b. be owner of victim, or 27231da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27241da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27251da177e4SLinus Torvalds * links pointing to it. 27260bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27270bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27280bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27290bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27300bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27311da177e4SLinus Torvalds * nfs_async_unlink(). 27321da177e4SLinus Torvalds */ 2733b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27341da177e4SLinus Torvalds { 273563afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27361da177e4SLinus Torvalds int error; 27371da177e4SLinus Torvalds 2738b18825a7SDavid Howells if (d_is_negative(victim)) 27391da177e4SLinus Torvalds return -ENOENT; 2740b18825a7SDavid Howells BUG_ON(!inode); 27411da177e4SLinus Torvalds 27421da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2743593d1ce8SEric W. Biederman 2744593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2745593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2746593d1ce8SEric W. Biederman return -EOVERFLOW; 2747593d1ce8SEric W. Biederman 27484fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27491da177e4SLinus Torvalds 2750f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27511da177e4SLinus Torvalds if (error) 27521da177e4SLinus Torvalds return error; 27531da177e4SLinus Torvalds if (IS_APPEND(dir)) 27541da177e4SLinus Torvalds return -EPERM; 2755b18825a7SDavid Howells 2756b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27570bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27581da177e4SLinus Torvalds return -EPERM; 27591da177e4SLinus Torvalds if (isdir) { 276044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27611da177e4SLinus Torvalds return -ENOTDIR; 27621da177e4SLinus Torvalds if (IS_ROOT(victim)) 27631da177e4SLinus Torvalds return -EBUSY; 276444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27651da177e4SLinus Torvalds return -EISDIR; 27661da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27671da177e4SLinus Torvalds return -ENOENT; 27681da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27691da177e4SLinus Torvalds return -EBUSY; 27701da177e4SLinus Torvalds return 0; 27711da177e4SLinus Torvalds } 27721da177e4SLinus Torvalds 27731da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27741da177e4SLinus Torvalds * dir. 27751da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27761da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27771da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2778036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2779036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2780036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27811da177e4SLinus Torvalds */ 2782a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27831da177e4SLinus Torvalds { 2784036d5236SEric W. Biederman struct user_namespace *s_user_ns; 278514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27861da177e4SLinus Torvalds if (child->d_inode) 27871da177e4SLinus Torvalds return -EEXIST; 27881da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27891da177e4SLinus Torvalds return -ENOENT; 2790036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2791036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2792036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2793036d5236SEric W. Biederman return -EOVERFLOW; 2794f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27951da177e4SLinus Torvalds } 27961da177e4SLinus Torvalds 27971da177e4SLinus Torvalds /* 27981da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27991da177e4SLinus Torvalds */ 28001da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28011da177e4SLinus Torvalds { 28021da177e4SLinus Torvalds struct dentry *p; 28031da177e4SLinus Torvalds 28041da177e4SLinus Torvalds if (p1 == p2) { 28055955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28061da177e4SLinus Torvalds return NULL; 28071da177e4SLinus Torvalds } 28081da177e4SLinus Torvalds 2809fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28101da177e4SLinus Torvalds 2811e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2812e2761a11SOGAWA Hirofumi if (p) { 28135955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28145955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28151da177e4SLinus Torvalds return p; 28161da177e4SLinus Torvalds } 28171da177e4SLinus Torvalds 2818e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2819e2761a11SOGAWA Hirofumi if (p) { 28205955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28215955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28221da177e4SLinus Torvalds return p; 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds 28255955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28265955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28271da177e4SLinus Torvalds return NULL; 28281da177e4SLinus Torvalds } 28294d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28301da177e4SLinus Torvalds 28311da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28321da177e4SLinus Torvalds { 28335955102cSAl Viro inode_unlock(p1->d_inode); 28341da177e4SLinus Torvalds if (p1 != p2) { 28355955102cSAl Viro inode_unlock(p2->d_inode); 2836fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds } 28394d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28401da177e4SLinus Torvalds 28414acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2842312b63fbSAl Viro bool want_excl) 28431da177e4SLinus Torvalds { 2844a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28451da177e4SLinus Torvalds if (error) 28461da177e4SLinus Torvalds return error; 28471da177e4SLinus Torvalds 2848acfa4380SAl Viro if (!dir->i_op->create) 28491da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28501da177e4SLinus Torvalds mode &= S_IALLUGO; 28511da177e4SLinus Torvalds mode |= S_IFREG; 28521da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28531da177e4SLinus Torvalds if (error) 28541da177e4SLinus Torvalds return error; 2855312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2856a74574aaSStephen Smalley if (!error) 2857f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28581da177e4SLinus Torvalds return error; 28591da177e4SLinus Torvalds } 28604d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28611da177e4SLinus Torvalds 28628e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28638e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28648e6c848eSAl Viro void *arg) 28658e6c848eSAl Viro { 28668e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28678e6c848eSAl Viro int error = may_create(dir, dentry); 28688e6c848eSAl Viro if (error) 28698e6c848eSAl Viro return error; 28708e6c848eSAl Viro 28718e6c848eSAl Viro mode &= S_IALLUGO; 28728e6c848eSAl Viro mode |= S_IFREG; 28738e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28748e6c848eSAl Viro if (error) 28758e6c848eSAl Viro return error; 28768e6c848eSAl Viro error = f(dentry, mode, arg); 28778e6c848eSAl Viro if (!error) 28788e6c848eSAl Viro fsnotify_create(dir, dentry); 28798e6c848eSAl Viro return error; 28808e6c848eSAl Viro } 28818e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28828e6c848eSAl Viro 2883a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2884a2982cc9SEric W. Biederman { 2885a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2886a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2887a2982cc9SEric W. Biederman } 2888a2982cc9SEric W. Biederman 2889f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28901da177e4SLinus Torvalds { 28913fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28921da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28931da177e4SLinus Torvalds int error; 28941da177e4SLinus Torvalds 28951da177e4SLinus Torvalds if (!inode) 28961da177e4SLinus Torvalds return -ENOENT; 28971da177e4SLinus Torvalds 2898c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2899c8fe8f30SChristoph Hellwig case S_IFLNK: 29001da177e4SLinus Torvalds return -ELOOP; 2901c8fe8f30SChristoph Hellwig case S_IFDIR: 2902c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29031da177e4SLinus Torvalds return -EISDIR; 2904c8fe8f30SChristoph Hellwig break; 2905c8fe8f30SChristoph Hellwig case S_IFBLK: 2906c8fe8f30SChristoph Hellwig case S_IFCHR: 2907a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29081da177e4SLinus Torvalds return -EACCES; 2909c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2910c8fe8f30SChristoph Hellwig case S_IFIFO: 2911c8fe8f30SChristoph Hellwig case S_IFSOCK: 29121da177e4SLinus Torvalds flag &= ~O_TRUNC; 2913c8fe8f30SChristoph Hellwig break; 29144a3fd211SDave Hansen } 2915b41572e9SDave Hansen 291662fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2917b41572e9SDave Hansen if (error) 2918b41572e9SDave Hansen return error; 29196146f0d5SMimi Zohar 29201da177e4SLinus Torvalds /* 29211da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29221da177e4SLinus Torvalds */ 29231da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29248737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29257715b521SAl Viro return -EPERM; 29261da177e4SLinus Torvalds if (flag & O_TRUNC) 29277715b521SAl Viro return -EPERM; 29281da177e4SLinus Torvalds } 29291da177e4SLinus Torvalds 29301da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29312e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29327715b521SAl Viro return -EPERM; 29331da177e4SLinus Torvalds 2934f3c7691eSJ. Bruce Fields return 0; 29357715b521SAl Viro } 29367715b521SAl Viro 2937e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29387715b521SAl Viro { 2939f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29407715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29417715b521SAl Viro int error = get_write_access(inode); 29421da177e4SLinus Torvalds if (error) 29437715b521SAl Viro return error; 29441da177e4SLinus Torvalds /* 29451da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29461da177e4SLinus Torvalds */ 2947d7a06983SJeff Layton error = locks_verify_locked(filp); 2948be6d3e56SKentaro Takeda if (!error) 2949ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29501da177e4SLinus Torvalds if (!error) { 29517715b521SAl Viro error = do_truncate(path->dentry, 0, 2952d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2953e1181ee6SJeff Layton filp); 29541da177e4SLinus Torvalds } 29551da177e4SLinus Torvalds put_write_access(inode); 2956acd0c935SMimi Zohar return error; 29571da177e4SLinus Torvalds } 29581da177e4SLinus Torvalds 2959d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2960d57999e1SDave Hansen { 29618a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29628a5e929dSAl Viro flag--; 2963d57999e1SDave Hansen return flag; 2964d57999e1SDave Hansen } 2965d57999e1SDave Hansen 2966d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2967d18e9008SMiklos Szeredi { 29681328c727SSeth Forshee struct user_namespace *s_user_ns; 2969d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2970d18e9008SMiklos Szeredi if (error) 2971d18e9008SMiklos Szeredi return error; 2972d18e9008SMiklos Szeredi 29731328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29741328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29751328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29761328c727SSeth Forshee return -EOVERFLOW; 29771328c727SSeth Forshee 2978d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2979d18e9008SMiklos Szeredi if (error) 2980d18e9008SMiklos Szeredi return error; 2981d18e9008SMiklos Szeredi 2982d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2983d18e9008SMiklos Szeredi } 2984d18e9008SMiklos Szeredi 29851acf0af9SDavid Howells /* 29861acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29871acf0af9SDavid Howells * dentry. 29881acf0af9SDavid Howells * 29891acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29901acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29911acf0af9SDavid Howells * 299200a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 299300a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 299400a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29951acf0af9SDavid Howells * 29961acf0af9SDavid Howells * Returns an error code otherwise. 29971acf0af9SDavid Howells */ 29982675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 299930d90494SAl Viro struct path *path, struct file *file, 3000015c3bbcSMiklos Szeredi const struct open_flags *op, 30013ec2eef1SAl Viro int open_flag, umode_t mode) 3002d18e9008SMiklos Szeredi { 3003d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3004d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3005d18e9008SMiklos Szeredi int error; 3006d18e9008SMiklos Szeredi 3007384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3008d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3009d18e9008SMiklos Szeredi 3010d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3011d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3012d18e9008SMiklos Szeredi 301330d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 301430d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30150fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 301644907d79SAl Viro open_to_namei_flags(open_flag), mode); 30176fbd0714SAl Viro d_lookup_done(dentry); 3018384f26e2SAl Viro if (!error) { 301964e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 3020d18e9008SMiklos Szeredi /* 3021384f26e2SAl Viro * We didn't have the inode before the open, so check open 3022384f26e2SAl Viro * permission here. 3023d18e9008SMiklos Szeredi */ 3024384f26e2SAl Viro int acc_mode = op->acc_mode; 302573a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 302603da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 302703da633aSAl Viro fsnotify_create(dir, dentry); 302862fb4a15SAl Viro acc_mode = 0; 302903da633aSAl Viro } 30302675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3031384f26e2SAl Viro if (WARN_ON(error > 0)) 3032384f26e2SAl Viro error = -EINVAL; 303364e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3034d18e9008SMiklos Szeredi error = -EIO; 3035384f26e2SAl Viro } else { 3036d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3037d18e9008SMiklos Szeredi dput(dentry); 3038d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 303910c64ceaSAl Viro } 304073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 3041d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3042a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3043a01e718fSAl Viro error = -ENOENT; 3044a01e718fSAl Viro } else { 3045d18e9008SMiklos Szeredi path->dentry = dentry; 3046d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 304700a07c15SAl Viro return 0; 3048d18e9008SMiklos Szeredi } 3049d18e9008SMiklos Szeredi } 3050a01e718fSAl Viro } 3051d18e9008SMiklos Szeredi dput(dentry); 3052d18e9008SMiklos Szeredi return error; 3053d18e9008SMiklos Szeredi } 3054d18e9008SMiklos Szeredi 305531e6b01fSNick Piggin /* 30561acf0af9SDavid Howells * Look up and maybe create and open the last component. 3057d58ffd35SMiklos Szeredi * 305800a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3059d58ffd35SMiklos Szeredi * 306000a07c15SAl Viro * Returns 0 on success, that is, if 306100a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 306200a07c15SAl Viro * the file was not completely opened at this time, though lookups and 306300a07c15SAl Viro * creations were performed. 306400a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 306500a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 306600a07c15SAl Viro * hadn't been specified. 30671acf0af9SDavid Howells * 306800a07c15SAl Viro * An error code is returned on failure. 3069d58ffd35SMiklos Szeredi */ 30702675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 307130d90494SAl Viro struct file *file, 3072d58ffd35SMiklos Szeredi const struct open_flags *op, 30733ec2eef1SAl Viro bool got_write) 3074d58ffd35SMiklos Szeredi { 3075d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 307654ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30771643b43fSAl Viro int open_flag = op->open_flag; 3078d58ffd35SMiklos Szeredi struct dentry *dentry; 30791643b43fSAl Viro int error, create_error = 0; 30801643b43fSAl Viro umode_t mode = op->mode; 30816fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3082d58ffd35SMiklos Szeredi 3083ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3084ce8644fcSAl Viro return -ENOENT; 3085d58ffd35SMiklos Szeredi 308673a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30876fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30886fbd0714SAl Viro for (;;) { 30896fbd0714SAl Viro if (!dentry) { 30906fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3091d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30922675a4ebSAl Viro return PTR_ERR(dentry); 30936fbd0714SAl Viro } 30946fbd0714SAl Viro if (d_in_lookup(dentry)) 30956fbd0714SAl Viro break; 3096d58ffd35SMiklos Szeredi 30976fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30986fbd0714SAl Viro if (likely(error > 0)) 30996fbd0714SAl Viro break; 31006fbd0714SAl Viro if (error) 31016fbd0714SAl Viro goto out_dput; 31026fbd0714SAl Viro d_invalidate(dentry); 31036fbd0714SAl Viro dput(dentry); 31046fbd0714SAl Viro dentry = NULL; 31056fbd0714SAl Viro } 31066fbd0714SAl Viro if (dentry->d_inode) { 3107d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3108d18e9008SMiklos Szeredi goto out_no_open; 31096c51e513SAl Viro } 3110d18e9008SMiklos Szeredi 31111643b43fSAl Viro /* 31121643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31131643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31141643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31151643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31161643b43fSAl Viro * 31171643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31181643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31191643b43fSAl Viro */ 31201643b43fSAl Viro if (open_flag & O_CREAT) { 31211643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31221643b43fSAl Viro mode &= ~current_umask(); 31231643b43fSAl Viro if (unlikely(!got_write)) { 31241643b43fSAl Viro create_error = -EROFS; 31251643b43fSAl Viro open_flag &= ~O_CREAT; 31261643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31271643b43fSAl Viro goto no_open; 31281643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31291643b43fSAl Viro } else { 31301643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31311643b43fSAl Viro if (create_error) { 31321643b43fSAl Viro open_flag &= ~O_CREAT; 31331643b43fSAl Viro if (open_flag & O_EXCL) 31341643b43fSAl Viro goto no_open; 31351643b43fSAl Viro } 31361643b43fSAl Viro } 31371643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31381643b43fSAl Viro unlikely(!got_write)) { 31391643b43fSAl Viro /* 31401643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31411643b43fSAl Viro * back to lookup + open 31421643b43fSAl Viro */ 31431643b43fSAl Viro goto no_open; 3144d18e9008SMiklos Szeredi } 3145d18e9008SMiklos Szeredi 31461643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31471643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31483ec2eef1SAl Viro mode); 31491643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31501643b43fSAl Viro error = create_error; 31511643b43fSAl Viro return error; 31521643b43fSAl Viro } 315354ef4872SMiklos Szeredi 31541643b43fSAl Viro no_open: 31556fbd0714SAl Viro if (d_in_lookup(dentry)) { 315612fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 315712fa5e24SAl Viro nd->flags); 31586fbd0714SAl Viro d_lookup_done(dentry); 315912fa5e24SAl Viro if (unlikely(res)) { 316012fa5e24SAl Viro if (IS_ERR(res)) { 316112fa5e24SAl Viro error = PTR_ERR(res); 316212fa5e24SAl Viro goto out_dput; 316312fa5e24SAl Viro } 316412fa5e24SAl Viro dput(dentry); 316512fa5e24SAl Viro dentry = res; 316612fa5e24SAl Viro } 316754ef4872SMiklos Szeredi } 316854ef4872SMiklos Szeredi 3169d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31701643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 317173a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3172ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3173ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3174ce8644fcSAl Viro error = -EACCES; 3175d58ffd35SMiklos Szeredi goto out_dput; 317664894cf8SAl Viro } 3177ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31781643b43fSAl Viro open_flag & O_EXCL); 3179d58ffd35SMiklos Szeredi if (error) 3180d58ffd35SMiklos Szeredi goto out_dput; 3181ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3182d58ffd35SMiklos Szeredi } 31831643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31841643b43fSAl Viro error = create_error; 3185d58ffd35SMiklos Szeredi goto out_dput; 3186d58ffd35SMiklos Szeredi } 3187d18e9008SMiklos Szeredi out_no_open: 3188d58ffd35SMiklos Szeredi path->dentry = dentry; 3189d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 319000a07c15SAl Viro return 0; 3191d58ffd35SMiklos Szeredi 3192d58ffd35SMiklos Szeredi out_dput: 3193d58ffd35SMiklos Szeredi dput(dentry); 31942675a4ebSAl Viro return error; 3195d58ffd35SMiklos Szeredi } 3196d58ffd35SMiklos Szeredi 3197d58ffd35SMiklos Szeredi /* 3198fe2d35ffSAl Viro * Handle the last step of open() 319931e6b01fSNick Piggin */ 3200896475d5SAl Viro static int do_last(struct nameidata *nd, 32013ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3202fb1cc555SAl Viro { 3203a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3204ca344a89SAl Viro int open_flag = op->open_flag; 320577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 320664894cf8SAl Viro bool got_write = false; 3207bcda7652SAl Viro int acc_mode = op->acc_mode; 3208254cf582SAl Viro unsigned seq; 3209a1eb3315SMiklos Szeredi struct inode *inode; 3210896475d5SAl Viro struct path path; 321116c2cd71SAl Viro int error; 3212fb1cc555SAl Viro 3213c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3214c3e380b0SAl Viro nd->flags |= op->intent; 3215c3e380b0SAl Viro 3216bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3217fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3218deb106c6SAl Viro if (unlikely(error)) 32192675a4ebSAl Viro return error; 3220e83db167SMiklos Szeredi goto finish_open; 32211f36f774SAl Viro } 3222a2c36b45SAl Viro 3223ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3224fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3225fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3226fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3227254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3228e9742b53SAl Viro if (likely(error > 0)) 322971574865SMiklos Szeredi goto finish_lookup; 323071574865SMiklos Szeredi 3231ce57dfc1SAl Viro if (error < 0) 3232deb106c6SAl Viro return error; 3233a1eb3315SMiklos Szeredi 323437d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32356583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3236b6183df7SMiklos Szeredi } else { 3237fe2d35ffSAl Viro /* create side of things */ 3238a3fbbde7SAl Viro /* 3239b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3240b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3241b6183df7SMiklos Szeredi * about to look up 3242a3fbbde7SAl Viro */ 32439f1fafeeSAl Viro error = complete_walk(nd); 3244e8bb73dfSAl Viro if (error) 32452675a4ebSAl Viro return error; 3246fe2d35ffSAl Viro 3247c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 32481f36f774SAl Viro /* trailing slashes? */ 3249deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3250deb106c6SAl Viro return -EISDIR; 3251b6183df7SMiklos Szeredi } 32521f36f774SAl Viro 32539cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 325464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 325564894cf8SAl Viro if (!error) 325664894cf8SAl Viro got_write = true; 325764894cf8SAl Viro /* 325864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 325964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 326064894cf8SAl Viro * dropping this one anyway. 326164894cf8SAl Viro */ 326264894cf8SAl Viro } 32639cf843e3SAl Viro if (open_flag & O_CREAT) 32645955102cSAl Viro inode_lock(dir->d_inode); 32659cf843e3SAl Viro else 32669cf843e3SAl Viro inode_lock_shared(dir->d_inode); 32673ec2eef1SAl Viro error = lookup_open(nd, &path, file, op, got_write); 32689cf843e3SAl Viro if (open_flag & O_CREAT) 32695955102cSAl Viro inode_unlock(dir->d_inode); 32709cf843e3SAl Viro else 32719cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3272fb1cc555SAl Viro 32732675a4ebSAl Viro if (error) 3274d58ffd35SMiklos Szeredi goto out; 32756c0d46c4SAl Viro 327600a07c15SAl Viro if (file->f_mode & FMODE_OPENED) { 327773a09dd9SAl Viro if ((file->f_mode & FMODE_CREATED) || 3278496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 327977d660a8SMiklos Szeredi will_truncate = false; 3280d18e9008SMiklos Szeredi 328176ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3282d18e9008SMiklos Szeredi goto opened; 3283d18e9008SMiklos Szeredi } 3284d18e9008SMiklos Szeredi 328573a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) { 32869b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3287ca344a89SAl Viro open_flag &= ~O_TRUNC; 328877d660a8SMiklos Szeredi will_truncate = false; 328962fb4a15SAl Viro acc_mode = 0; 3290896475d5SAl Viro path_to_nameidata(&path, nd); 3291e83db167SMiklos Szeredi goto finish_open_created; 3292fb1cc555SAl Viro } 3293fb1cc555SAl Viro 3294fb1cc555SAl Viro /* 3295d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3296d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3297d18e9008SMiklos Szeredi * necessary...) 3298d18e9008SMiklos Szeredi */ 329964894cf8SAl Viro if (got_write) { 3300d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 330164894cf8SAl Viro got_write = false; 3302d18e9008SMiklos Szeredi } 3303d18e9008SMiklos Szeredi 3304e6ec03a2SAl Viro error = follow_managed(&path, nd); 3305e6ec03a2SAl Viro if (unlikely(error < 0)) 3306e6ec03a2SAl Viro return error; 3307e6ec03a2SAl Viro 33086583fe22SAl Viro /* 33096583fe22SAl Viro * create/update audit record if it already exists. 33106583fe22SAl Viro */ 33116583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33126583fe22SAl Viro 3313deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3314deb106c6SAl Viro path_to_nameidata(&path, nd); 3315deb106c6SAl Viro return -EEXIST; 3316deb106c6SAl Viro } 3317fb1cc555SAl Viro 3318254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3319d4565649SAl Viro inode = d_backing_inode(path.dentry); 3320766c4cbfSAl Viro finish_lookup: 33218f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3322deb106c6SAl Viro if (unlikely(error)) 3323d63ff28fSAl Viro return error; 3324bc77daa7SAl Viro finish_open: 33258f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3326a3fbbde7SAl Viro error = complete_walk(nd); 3327fac7d191SAl Viro if (error) 33282675a4ebSAl Viro return error; 332976ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 333030aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 3331fb1cc555SAl Viro error = -EISDIR; 333230aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 33332675a4ebSAl Viro goto out; 333430aba665SSalvatore Mesoraca error = may_create_in_sticky(dir, 333530aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 333630aba665SSalvatore Mesoraca if (unlikely(error)) 333730aba665SSalvatore Mesoraca goto out; 333830aba665SSalvatore Mesoraca } 3339af2f5542SMiklos Szeredi error = -ENOTDIR; 334044b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33412675a4ebSAl Viro goto out; 33424bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 334377d660a8SMiklos Szeredi will_truncate = false; 33446c0d46c4SAl Viro 33450f9d1a10SAl Viro if (will_truncate) { 33460f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33470f9d1a10SAl Viro if (error) 33482675a4ebSAl Viro goto out; 334964894cf8SAl Viro got_write = true; 33500f9d1a10SAl Viro } 3351e83db167SMiklos Szeredi finish_open_created: 3352bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3353ca344a89SAl Viro if (error) 33542675a4ebSAl Viro goto out; 3355aad888f8SAl Viro BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ 3356ae2bb293SAl Viro error = vfs_open(&nd->path, file); 3357fac7d191SAl Viro if (error) 3358015c3bbcSMiklos Szeredi goto out; 3359a8277b9bSMiklos Szeredi opened: 33606035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 3361fe9ec829SAl Viro if (!error && will_truncate) 33622675a4ebSAl Viro error = handle_truncate(file); 3363ca344a89SAl Viro out: 3364c80567c8SAl Viro if (unlikely(error > 0)) { 3365c80567c8SAl Viro WARN_ON(1); 3366c80567c8SAl Viro error = -EINVAL; 3367c80567c8SAl Viro } 336864894cf8SAl Viro if (got_write) 33690f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33702675a4ebSAl Viro return error; 3371fb1cc555SAl Viro } 3372fb1cc555SAl Viro 3373af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3374af7bd4dcSAmir Goldstein { 3375af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3376af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3377af7bd4dcSAmir Goldstein struct inode *inode; 3378af7bd4dcSAmir Goldstein int error; 3379af7bd4dcSAmir Goldstein 3380af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3381af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3382af7bd4dcSAmir Goldstein if (error) 3383af7bd4dcSAmir Goldstein goto out_err; 3384af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3385af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3386af7bd4dcSAmir Goldstein goto out_err; 3387af7bd4dcSAmir Goldstein error = -ENOMEM; 3388cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3389af7bd4dcSAmir Goldstein if (unlikely(!child)) 3390af7bd4dcSAmir Goldstein goto out_err; 3391af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3392af7bd4dcSAmir Goldstein if (error) 3393af7bd4dcSAmir Goldstein goto out_err; 3394af7bd4dcSAmir Goldstein error = -ENOENT; 3395af7bd4dcSAmir Goldstein inode = child->d_inode; 3396af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3397af7bd4dcSAmir Goldstein goto out_err; 3398af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3399af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3400af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3401af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3402af7bd4dcSAmir Goldstein } 3403fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3404af7bd4dcSAmir Goldstein return child; 3405af7bd4dcSAmir Goldstein 3406af7bd4dcSAmir Goldstein out_err: 3407af7bd4dcSAmir Goldstein dput(child); 3408af7bd4dcSAmir Goldstein return ERR_PTR(error); 3409af7bd4dcSAmir Goldstein } 3410af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3411af7bd4dcSAmir Goldstein 3412c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 341360545d0dSAl Viro const struct open_flags *op, 34143ec2eef1SAl Viro struct file *file) 341560545d0dSAl Viro { 3416625b6d10SAl Viro struct dentry *child; 3417625b6d10SAl Viro struct path path; 3418c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 341960545d0dSAl Viro if (unlikely(error)) 342060545d0dSAl Viro return error; 3421625b6d10SAl Viro error = mnt_want_write(path.mnt); 342260545d0dSAl Viro if (unlikely(error)) 342360545d0dSAl Viro goto out; 3424af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3425af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3426684e73beSHirofumi Nakagawa if (IS_ERR(child)) 342760545d0dSAl Viro goto out2; 3428625b6d10SAl Viro dput(path.dentry); 3429625b6d10SAl Viro path.dentry = child; 3430c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 343169a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 343262fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 343360545d0dSAl Viro if (error) 343460545d0dSAl Viro goto out2; 3435625b6d10SAl Viro file->f_path.mnt = path.mnt; 3436be12af3eSAl Viro error = finish_open(file, child, NULL); 343760545d0dSAl Viro out2: 3438625b6d10SAl Viro mnt_drop_write(path.mnt); 343960545d0dSAl Viro out: 3440625b6d10SAl Viro path_put(&path); 344160545d0dSAl Viro return error; 344260545d0dSAl Viro } 344360545d0dSAl Viro 34446ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34456ac08709SAl Viro { 34466ac08709SAl Viro struct path path; 34476ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34486ac08709SAl Viro if (!error) { 34496ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3450ae2bb293SAl Viro error = vfs_open(&path, file); 34516ac08709SAl Viro path_put(&path); 34526ac08709SAl Viro } 34536ac08709SAl Viro return error; 34546ac08709SAl Viro } 34556ac08709SAl Viro 3456c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3457c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34581da177e4SLinus Torvalds { 345930d90494SAl Viro struct file *file; 346013aab428SAl Viro int error; 346131e6b01fSNick Piggin 3462ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 34631afc99beSAl Viro if (IS_ERR(file)) 34641afc99beSAl Viro return file; 346531e6b01fSNick Piggin 3466bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 34673ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 34685f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 34696ac08709SAl Viro error = do_o_path(nd, flags, file); 34705f336e72SAl Viro } else { 34715f336e72SAl Viro const char *s = path_init(nd, flags); 34723bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 34733ec2eef1SAl Viro (error = do_last(nd, file, op)) > 0) { 347473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 34753bdba28bSAl Viro s = trailing_symlink(nd); 34763bdba28bSAl Viro } 3477deb106c6SAl Viro terminate_walk(nd); 34785f336e72SAl Viro } 34797c1c01ecSAl Viro if (likely(!error)) { 3480aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34817c1c01ecSAl Viro return file; 34827c1c01ecSAl Viro WARN_ON(1); 34837c1c01ecSAl Viro error = -EINVAL; 3484015c3bbcSMiklos Szeredi } 34857c1c01ecSAl Viro fput(file); 34862675a4ebSAl Viro if (error == -EOPENSTALE) { 34872675a4ebSAl Viro if (flags & LOOKUP_RCU) 34882675a4ebSAl Viro error = -ECHILD; 34892675a4ebSAl Viro else 34902675a4ebSAl Viro error = -ESTALE; 34912675a4ebSAl Viro } 34927c1c01ecSAl Viro return ERR_PTR(error); 3493de459215SKirill Korotaev } 34941da177e4SLinus Torvalds 3495669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3496f9652e10SAl Viro const struct open_flags *op) 349713aab428SAl Viro { 34989883d185SAl Viro struct nameidata nd; 3499f9652e10SAl Viro int flags = op->lookup_flags; 350013aab428SAl Viro struct file *filp; 350113aab428SAl Viro 35029883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3503c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 350413aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3505c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 350613aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3507c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35089883d185SAl Viro restore_nameidata(); 350913aab428SAl Viro return filp; 351013aab428SAl Viro } 351113aab428SAl Viro 351273d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3513f9652e10SAl Viro const char *name, const struct open_flags *op) 351473d049a4SAl Viro { 35159883d185SAl Viro struct nameidata nd; 351673d049a4SAl Viro struct file *file; 351751689104SPaul Moore struct filename *filename; 3518f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 351973d049a4SAl Viro 352073d049a4SAl Viro nd.root.mnt = mnt; 352173d049a4SAl Viro nd.root.dentry = dentry; 352273d049a4SAl Viro 3523b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 352473d049a4SAl Viro return ERR_PTR(-ELOOP); 352573d049a4SAl Viro 352651689104SPaul Moore filename = getname_kernel(name); 3527a1c83681SViresh Kumar if (IS_ERR(filename)) 352851689104SPaul Moore return ERR_CAST(filename); 352951689104SPaul Moore 35309883d185SAl Viro set_nameidata(&nd, -1, filename); 3531c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 353273d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3533c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 353473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3535c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35369883d185SAl Viro restore_nameidata(); 353751689104SPaul Moore putname(filename); 353873d049a4SAl Viro return file; 353973d049a4SAl Viro } 354073d049a4SAl Viro 3541fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35421ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35431da177e4SLinus Torvalds { 3544c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3545391172c4SAl Viro struct qstr last; 3546391172c4SAl Viro int type; 3547c30dabfeSJan Kara int err2; 35481ac12b4bSJeff Layton int error; 35491ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35501ac12b4bSJeff Layton 35511ac12b4bSJeff Layton /* 35521ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35531ac12b4bSJeff Layton * other flags passed in are ignored! 35541ac12b4bSJeff Layton */ 35551ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35561ac12b4bSJeff Layton 35575c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35585c31b6ceSAl Viro if (IS_ERR(name)) 35595c31b6ceSAl Viro return ERR_CAST(name); 35601da177e4SLinus Torvalds 3561c663e5d8SChristoph Hellwig /* 3562c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3563c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3564c663e5d8SChristoph Hellwig */ 35655c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3566ed75e95dSAl Viro goto out; 3567c663e5d8SChristoph Hellwig 3568c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3569391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3570c663e5d8SChristoph Hellwig /* 3571c663e5d8SChristoph Hellwig * Do the final lookup. 3572c663e5d8SChristoph Hellwig */ 3573391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 35745955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3575391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 35761da177e4SLinus Torvalds if (IS_ERR(dentry)) 3577a8104a9fSAl Viro goto unlock; 3578c663e5d8SChristoph Hellwig 3579a8104a9fSAl Viro error = -EEXIST; 3580b18825a7SDavid Howells if (d_is_positive(dentry)) 3581a8104a9fSAl Viro goto fail; 3582b18825a7SDavid Howells 3583c663e5d8SChristoph Hellwig /* 3584c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3585c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3586c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3587c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3588c663e5d8SChristoph Hellwig */ 3589391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3590a8104a9fSAl Viro error = -ENOENT; 3591ed75e95dSAl Viro goto fail; 3592e9baf6e5SAl Viro } 3593c30dabfeSJan Kara if (unlikely(err2)) { 3594c30dabfeSJan Kara error = err2; 3595a8104a9fSAl Viro goto fail; 3596c30dabfeSJan Kara } 3597181c37b6SAl Viro putname(name); 3598e9baf6e5SAl Viro return dentry; 35991da177e4SLinus Torvalds fail: 3600a8104a9fSAl Viro dput(dentry); 3601a8104a9fSAl Viro dentry = ERR_PTR(error); 3602a8104a9fSAl Viro unlock: 36035955102cSAl Viro inode_unlock(path->dentry->d_inode); 3604c30dabfeSJan Kara if (!err2) 3605391172c4SAl Viro mnt_drop_write(path->mnt); 3606ed75e95dSAl Viro out: 3607391172c4SAl Viro path_put(path); 3608181c37b6SAl Viro putname(name); 3609ed75e95dSAl Viro return dentry; 3610dae6ad8fSAl Viro } 3611fa14a0b8SAl Viro 3612fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3613fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3614fa14a0b8SAl Viro { 3615181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3616181c37b6SAl Viro path, lookup_flags); 3617fa14a0b8SAl Viro } 3618dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3619dae6ad8fSAl Viro 3620921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3621921a1650SAl Viro { 3622921a1650SAl Viro dput(dentry); 36235955102cSAl Viro inode_unlock(path->dentry->d_inode); 3624a8104a9fSAl Viro mnt_drop_write(path->mnt); 3625921a1650SAl Viro path_put(path); 3626921a1650SAl Viro } 3627921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3628921a1650SAl Viro 3629520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36301ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3631dae6ad8fSAl Viro { 3632181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3633dae6ad8fSAl Viro } 3634dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3635dae6ad8fSAl Viro 36361a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36371da177e4SLinus Torvalds { 3638a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36391da177e4SLinus Torvalds 36401da177e4SLinus Torvalds if (error) 36411da177e4SLinus Torvalds return error; 36421da177e4SLinus Torvalds 364394f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36441da177e4SLinus Torvalds return -EPERM; 36451da177e4SLinus Torvalds 3646acfa4380SAl Viro if (!dir->i_op->mknod) 36471da177e4SLinus Torvalds return -EPERM; 36481da177e4SLinus Torvalds 364908ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 365008ce5f16SSerge E. Hallyn if (error) 365108ce5f16SSerge E. Hallyn return error; 365208ce5f16SSerge E. Hallyn 36531da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36541da177e4SLinus Torvalds if (error) 36551da177e4SLinus Torvalds return error; 36561da177e4SLinus Torvalds 36571da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3658a74574aaSStephen Smalley if (!error) 3659f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36601da177e4SLinus Torvalds return error; 36611da177e4SLinus Torvalds } 36624d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36631da177e4SLinus Torvalds 3664f69aac00SAl Viro static int may_mknod(umode_t mode) 3665463c3197SDave Hansen { 3666463c3197SDave Hansen switch (mode & S_IFMT) { 3667463c3197SDave Hansen case S_IFREG: 3668463c3197SDave Hansen case S_IFCHR: 3669463c3197SDave Hansen case S_IFBLK: 3670463c3197SDave Hansen case S_IFIFO: 3671463c3197SDave Hansen case S_IFSOCK: 3672463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3673463c3197SDave Hansen return 0; 3674463c3197SDave Hansen case S_IFDIR: 3675463c3197SDave Hansen return -EPERM; 3676463c3197SDave Hansen default: 3677463c3197SDave Hansen return -EINVAL; 3678463c3197SDave Hansen } 3679463c3197SDave Hansen } 3680463c3197SDave Hansen 368187c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 368287c4e192SDominik Brodowski unsigned int dev) 36831da177e4SLinus Torvalds { 36841da177e4SLinus Torvalds struct dentry *dentry; 3685dae6ad8fSAl Viro struct path path; 3686dae6ad8fSAl Viro int error; 3687972567f1SJeff Layton unsigned int lookup_flags = 0; 36881da177e4SLinus Torvalds 36898e4bfca1SAl Viro error = may_mknod(mode); 36908e4bfca1SAl Viro if (error) 36918e4bfca1SAl Viro return error; 3692972567f1SJeff Layton retry: 3693972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3694dae6ad8fSAl Viro if (IS_ERR(dentry)) 3695dae6ad8fSAl Viro return PTR_ERR(dentry); 36962ad94ae6SAl Viro 3697dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3698ce3b0f8dSAl Viro mode &= ~current_umask(); 3699dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3700be6d3e56SKentaro Takeda if (error) 3701a8104a9fSAl Viro goto out; 37021da177e4SLinus Torvalds switch (mode & S_IFMT) { 37031da177e4SLinus Torvalds case 0: case S_IFREG: 3704312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 370505d1a717SMimi Zohar if (!error) 370605d1a717SMimi Zohar ima_post_path_mknod(dentry); 37071da177e4SLinus Torvalds break; 37081da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3709dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37101da177e4SLinus Torvalds new_decode_dev(dev)); 37111da177e4SLinus Torvalds break; 37121da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3713dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37141da177e4SLinus Torvalds break; 37151da177e4SLinus Torvalds } 3716a8104a9fSAl Viro out: 3717921a1650SAl Viro done_path_create(&path, dentry); 3718972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3719972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3720972567f1SJeff Layton goto retry; 3721972567f1SJeff Layton } 37221da177e4SLinus Torvalds return error; 37231da177e4SLinus Torvalds } 37241da177e4SLinus Torvalds 372587c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 372687c4e192SDominik Brodowski unsigned int, dev) 372787c4e192SDominik Brodowski { 372887c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 372987c4e192SDominik Brodowski } 373087c4e192SDominik Brodowski 37318208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37325590ff0dSUlrich Drepper { 373387c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 37345590ff0dSUlrich Drepper } 37355590ff0dSUlrich Drepper 373618bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37371da177e4SLinus Torvalds { 3738a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37398de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37401da177e4SLinus Torvalds 37411da177e4SLinus Torvalds if (error) 37421da177e4SLinus Torvalds return error; 37431da177e4SLinus Torvalds 3744acfa4380SAl Viro if (!dir->i_op->mkdir) 37451da177e4SLinus Torvalds return -EPERM; 37461da177e4SLinus Torvalds 37471da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37481da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37491da177e4SLinus Torvalds if (error) 37501da177e4SLinus Torvalds return error; 37511da177e4SLinus Torvalds 37528de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37538de52778SAl Viro return -EMLINK; 37548de52778SAl Viro 37551da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3756a74574aaSStephen Smalley if (!error) 3757f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37581da177e4SLinus Torvalds return error; 37591da177e4SLinus Torvalds } 37604d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37611da177e4SLinus Torvalds 37620101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 37631da177e4SLinus Torvalds { 37646902d925SDave Hansen struct dentry *dentry; 3765dae6ad8fSAl Viro struct path path; 3766dae6ad8fSAl Viro int error; 3767b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37681da177e4SLinus Torvalds 3769b76d8b82SJeff Layton retry: 3770b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37716902d925SDave Hansen if (IS_ERR(dentry)) 3772dae6ad8fSAl Viro return PTR_ERR(dentry); 37736902d925SDave Hansen 3774dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3775ce3b0f8dSAl Viro mode &= ~current_umask(); 3776dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3777a8104a9fSAl Viro if (!error) 3778dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3779921a1650SAl Viro done_path_create(&path, dentry); 3780b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3781b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3782b76d8b82SJeff Layton goto retry; 3783b76d8b82SJeff Layton } 37841da177e4SLinus Torvalds return error; 37851da177e4SLinus Torvalds } 37861da177e4SLinus Torvalds 37870101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37880101db7aSDominik Brodowski { 37890101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37900101db7aSDominik Brodowski } 37910101db7aSDominik Brodowski 3792a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37935590ff0dSUlrich Drepper { 37940101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37955590ff0dSUlrich Drepper } 37965590ff0dSUlrich Drepper 37971da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37981da177e4SLinus Torvalds { 37991da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38001da177e4SLinus Torvalds 38011da177e4SLinus Torvalds if (error) 38021da177e4SLinus Torvalds return error; 38031da177e4SLinus Torvalds 3804acfa4380SAl Viro if (!dir->i_op->rmdir) 38051da177e4SLinus Torvalds return -EPERM; 38061da177e4SLinus Torvalds 38071d2ef590SAl Viro dget(dentry); 38085955102cSAl Viro inode_lock(dentry->d_inode); 3809912dbc15SSage Weil 38101da177e4SLinus Torvalds error = -EBUSY; 38117af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3812912dbc15SSage Weil goto out; 3813912dbc15SSage Weil 38141da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3815912dbc15SSage Weil if (error) 3816912dbc15SSage Weil goto out; 3817912dbc15SSage Weil 38181da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3819912dbc15SSage Weil if (error) 3820912dbc15SSage Weil goto out; 3821912dbc15SSage Weil 38228767712fSAl Viro shrink_dcache_parent(dentry); 38231da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3824d83c49f3SAl Viro dont_mount(dentry); 38258ed936b5SEric W. Biederman detach_mounts(dentry); 3826116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 38271da177e4SLinus Torvalds 3828912dbc15SSage Weil out: 38295955102cSAl Viro inode_unlock(dentry->d_inode); 38301d2ef590SAl Viro dput(dentry); 3831912dbc15SSage Weil if (!error) 3832912dbc15SSage Weil d_delete(dentry); 38331da177e4SLinus Torvalds return error; 38341da177e4SLinus Torvalds } 38354d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38361da177e4SLinus Torvalds 3837f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 38381da177e4SLinus Torvalds { 38391da177e4SLinus Torvalds int error = 0; 384091a27b2aSJeff Layton struct filename *name; 38411da177e4SLinus Torvalds struct dentry *dentry; 3842f5beed75SAl Viro struct path path; 3843f5beed75SAl Viro struct qstr last; 3844f5beed75SAl Viro int type; 3845c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3846c6ee9206SJeff Layton retry: 3847c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3848c1d4dd27SAl Viro &path, &last, &type); 384991a27b2aSJeff Layton if (IS_ERR(name)) 385091a27b2aSJeff Layton return PTR_ERR(name); 38511da177e4SLinus Torvalds 3852f5beed75SAl Viro switch (type) { 38531da177e4SLinus Torvalds case LAST_DOTDOT: 38541da177e4SLinus Torvalds error = -ENOTEMPTY; 38551da177e4SLinus Torvalds goto exit1; 38561da177e4SLinus Torvalds case LAST_DOT: 38571da177e4SLinus Torvalds error = -EINVAL; 38581da177e4SLinus Torvalds goto exit1; 38591da177e4SLinus Torvalds case LAST_ROOT: 38601da177e4SLinus Torvalds error = -EBUSY; 38611da177e4SLinus Torvalds goto exit1; 38621da177e4SLinus Torvalds } 38630612d9fbSOGAWA Hirofumi 3864f5beed75SAl Viro error = mnt_want_write(path.mnt); 3865c30dabfeSJan Kara if (error) 3866c30dabfeSJan Kara goto exit1; 38670612d9fbSOGAWA Hirofumi 38685955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3869f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38701da177e4SLinus Torvalds error = PTR_ERR(dentry); 38716902d925SDave Hansen if (IS_ERR(dentry)) 38726902d925SDave Hansen goto exit2; 3873e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3874e6bc45d6STheodore Ts'o error = -ENOENT; 3875e6bc45d6STheodore Ts'o goto exit3; 3876e6bc45d6STheodore Ts'o } 3877f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3878be6d3e56SKentaro Takeda if (error) 3879c30dabfeSJan Kara goto exit3; 3880f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38810622753bSDave Hansen exit3: 38821da177e4SLinus Torvalds dput(dentry); 38836902d925SDave Hansen exit2: 38845955102cSAl Viro inode_unlock(path.dentry->d_inode); 3885f5beed75SAl Viro mnt_drop_write(path.mnt); 38861da177e4SLinus Torvalds exit1: 3887f5beed75SAl Viro path_put(&path); 38881da177e4SLinus Torvalds putname(name); 3889c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3890c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3891c6ee9206SJeff Layton goto retry; 3892c6ee9206SJeff Layton } 38931da177e4SLinus Torvalds return error; 38941da177e4SLinus Torvalds } 38951da177e4SLinus Torvalds 38963cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38975590ff0dSUlrich Drepper { 38985590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38995590ff0dSUlrich Drepper } 39005590ff0dSUlrich Drepper 3901b21996e3SJ. Bruce Fields /** 3902b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3903b21996e3SJ. Bruce Fields * @dir: parent directory 3904b21996e3SJ. Bruce Fields * @dentry: victim 3905b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3906b21996e3SJ. Bruce Fields * 3907b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3908b21996e3SJ. Bruce Fields * 3909b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3910b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3911b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3912b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3913b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3914b21996e3SJ. Bruce Fields * 3915b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3916b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3917b21996e3SJ. Bruce Fields * to be NFS exported. 3918b21996e3SJ. Bruce Fields */ 3919b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39201da177e4SLinus Torvalds { 39219accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39221da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39231da177e4SLinus Torvalds 39241da177e4SLinus Torvalds if (error) 39251da177e4SLinus Torvalds return error; 39261da177e4SLinus Torvalds 3927acfa4380SAl Viro if (!dir->i_op->unlink) 39281da177e4SLinus Torvalds return -EPERM; 39291da177e4SLinus Torvalds 39305955102cSAl Viro inode_lock(target); 39318ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39321da177e4SLinus Torvalds error = -EBUSY; 39331da177e4SLinus Torvalds else { 39341da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3935bec1052eSAl Viro if (!error) { 39365a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39375a14696cSJ. Bruce Fields if (error) 3938b21996e3SJ. Bruce Fields goto out; 39391da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39408ed936b5SEric W. Biederman if (!error) { 3941d83c49f3SAl Viro dont_mount(dentry); 39428ed936b5SEric W. Biederman detach_mounts(dentry); 3943116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 39448ed936b5SEric W. Biederman } 3945bec1052eSAl Viro } 39461da177e4SLinus Torvalds } 3947b21996e3SJ. Bruce Fields out: 39485955102cSAl Viro inode_unlock(target); 39491da177e4SLinus Torvalds 39501da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39511da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39529accbb97SJ. Bruce Fields fsnotify_link_count(target); 39531da177e4SLinus Torvalds d_delete(dentry); 39541da177e4SLinus Torvalds } 39550eeca283SRobert Love 39561da177e4SLinus Torvalds return error; 39571da177e4SLinus Torvalds } 39584d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39591da177e4SLinus Torvalds 39601da177e4SLinus Torvalds /* 39611da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39621b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39631da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39641da177e4SLinus Torvalds * while waiting on the I/O. 39651da177e4SLinus Torvalds */ 3966da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39671da177e4SLinus Torvalds { 39682ad94ae6SAl Viro int error; 39691da177e4SLinus Torvalds struct dentry *dentry; 3970f5beed75SAl Viro struct path path; 3971f5beed75SAl Viro struct qstr last; 3972f5beed75SAl Viro int type; 39731da177e4SLinus Torvalds struct inode *inode = NULL; 3974b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39755d18f813SJeff Layton unsigned int lookup_flags = 0; 39765d18f813SJeff Layton retry: 3977da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 397891a27b2aSJeff Layton if (IS_ERR(name)) 397991a27b2aSJeff Layton return PTR_ERR(name); 39802ad94ae6SAl Viro 39811da177e4SLinus Torvalds error = -EISDIR; 3982f5beed75SAl Viro if (type != LAST_NORM) 39831da177e4SLinus Torvalds goto exit1; 39840612d9fbSOGAWA Hirofumi 3985f5beed75SAl Viro error = mnt_want_write(path.mnt); 3986c30dabfeSJan Kara if (error) 3987c30dabfeSJan Kara goto exit1; 3988b21996e3SJ. Bruce Fields retry_deleg: 39895955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3990f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39911da177e4SLinus Torvalds error = PTR_ERR(dentry); 39921da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39931da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3994f5beed75SAl Viro if (last.name[last.len]) 399550338b88STörök Edwin goto slashes; 39961da177e4SLinus Torvalds inode = dentry->d_inode; 3997b18825a7SDavid Howells if (d_is_negative(dentry)) 3998e6bc45d6STheodore Ts'o goto slashes; 39997de9c6eeSAl Viro ihold(inode); 4000f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4001be6d3e56SKentaro Takeda if (error) 4002c30dabfeSJan Kara goto exit2; 4003f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40041da177e4SLinus Torvalds exit2: 40051da177e4SLinus Torvalds dput(dentry); 40061da177e4SLinus Torvalds } 40075955102cSAl Viro inode_unlock(path.dentry->d_inode); 40081da177e4SLinus Torvalds if (inode) 40091da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4010b21996e3SJ. Bruce Fields inode = NULL; 4011b21996e3SJ. Bruce Fields if (delegated_inode) { 40125a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4013b21996e3SJ. Bruce Fields if (!error) 4014b21996e3SJ. Bruce Fields goto retry_deleg; 4015b21996e3SJ. Bruce Fields } 4016f5beed75SAl Viro mnt_drop_write(path.mnt); 40171da177e4SLinus Torvalds exit1: 4018f5beed75SAl Viro path_put(&path); 40195d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40205d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40215d18f813SJeff Layton inode = NULL; 40225d18f813SJeff Layton goto retry; 40235d18f813SJeff Layton } 4024da2f1362SChristoph Hellwig putname(name); 40251da177e4SLinus Torvalds return error; 40261da177e4SLinus Torvalds 40271da177e4SLinus Torvalds slashes: 4028b18825a7SDavid Howells if (d_is_negative(dentry)) 4029b18825a7SDavid Howells error = -ENOENT; 403044b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4031b18825a7SDavid Howells error = -EISDIR; 4032b18825a7SDavid Howells else 4033b18825a7SDavid Howells error = -ENOTDIR; 40341da177e4SLinus Torvalds goto exit2; 40351da177e4SLinus Torvalds } 40361da177e4SLinus Torvalds 40372e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40385590ff0dSUlrich Drepper { 40395590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40405590ff0dSUlrich Drepper return -EINVAL; 40415590ff0dSUlrich Drepper 40425590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40435590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40445590ff0dSUlrich Drepper 4045da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40465590ff0dSUlrich Drepper } 40475590ff0dSUlrich Drepper 40483480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40495590ff0dSUlrich Drepper { 4050da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40515590ff0dSUlrich Drepper } 40525590ff0dSUlrich Drepper 4053db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40541da177e4SLinus Torvalds { 4055a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40561da177e4SLinus Torvalds 40571da177e4SLinus Torvalds if (error) 40581da177e4SLinus Torvalds return error; 40591da177e4SLinus Torvalds 4060acfa4380SAl Viro if (!dir->i_op->symlink) 40611da177e4SLinus Torvalds return -EPERM; 40621da177e4SLinus Torvalds 40631da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40641da177e4SLinus Torvalds if (error) 40651da177e4SLinus Torvalds return error; 40661da177e4SLinus Torvalds 40671da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4068a74574aaSStephen Smalley if (!error) 4069f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40701da177e4SLinus Torvalds return error; 40711da177e4SLinus Torvalds } 40724d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40731da177e4SLinus Torvalds 4074b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 4075b724e846SDominik Brodowski const char __user *newname) 40761da177e4SLinus Torvalds { 40772ad94ae6SAl Viro int error; 407891a27b2aSJeff Layton struct filename *from; 40796902d925SDave Hansen struct dentry *dentry; 4080dae6ad8fSAl Viro struct path path; 4081f46d3567SJeff Layton unsigned int lookup_flags = 0; 40821da177e4SLinus Torvalds 40831da177e4SLinus Torvalds from = getname(oldname); 40841da177e4SLinus Torvalds if (IS_ERR(from)) 40851da177e4SLinus Torvalds return PTR_ERR(from); 4086f46d3567SJeff Layton retry: 4087f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40881da177e4SLinus Torvalds error = PTR_ERR(dentry); 40896902d925SDave Hansen if (IS_ERR(dentry)) 4090dae6ad8fSAl Viro goto out_putname; 40916902d925SDave Hansen 409291a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4093a8104a9fSAl Viro if (!error) 409491a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4095921a1650SAl Viro done_path_create(&path, dentry); 4096f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4097f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4098f46d3567SJeff Layton goto retry; 4099f46d3567SJeff Layton } 41006902d925SDave Hansen out_putname: 41011da177e4SLinus Torvalds putname(from); 41021da177e4SLinus Torvalds return error; 41031da177e4SLinus Torvalds } 41041da177e4SLinus Torvalds 4105b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4106b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4107b724e846SDominik Brodowski { 4108b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4109b724e846SDominik Brodowski } 4110b724e846SDominik Brodowski 41113480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41125590ff0dSUlrich Drepper { 4113b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 41145590ff0dSUlrich Drepper } 41155590ff0dSUlrich Drepper 4116146a8595SJ. Bruce Fields /** 4117146a8595SJ. Bruce Fields * vfs_link - create a new link 4118146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4119146a8595SJ. Bruce Fields * @dir: new parent 4120146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4121146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4122146a8595SJ. Bruce Fields * 4123146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4124146a8595SJ. Bruce Fields * 4125146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4126146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4127146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4128146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4129146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4130146a8595SJ. Bruce Fields * 4131146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4132146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4133146a8595SJ. Bruce Fields * to be NFS exported. 4134146a8595SJ. Bruce Fields */ 4135146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41361da177e4SLinus Torvalds { 41371da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41388de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41391da177e4SLinus Torvalds int error; 41401da177e4SLinus Torvalds 41411da177e4SLinus Torvalds if (!inode) 41421da177e4SLinus Torvalds return -ENOENT; 41431da177e4SLinus Torvalds 4144a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41451da177e4SLinus Torvalds if (error) 41461da177e4SLinus Torvalds return error; 41471da177e4SLinus Torvalds 41481da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41491da177e4SLinus Torvalds return -EXDEV; 41501da177e4SLinus Torvalds 41511da177e4SLinus Torvalds /* 41521da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41531da177e4SLinus Torvalds */ 41541da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41551da177e4SLinus Torvalds return -EPERM; 41560bd23d09SEric W. Biederman /* 41570bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41580bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41590bd23d09SEric W. Biederman * the vfs. 41600bd23d09SEric W. Biederman */ 41610bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41620bd23d09SEric W. Biederman return -EPERM; 4163acfa4380SAl Viro if (!dir->i_op->link) 41641da177e4SLinus Torvalds return -EPERM; 41657e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41661da177e4SLinus Torvalds return -EPERM; 41671da177e4SLinus Torvalds 41681da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41691da177e4SLinus Torvalds if (error) 41701da177e4SLinus Torvalds return error; 41711da177e4SLinus Torvalds 41725955102cSAl Viro inode_lock(inode); 4173aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4174f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4175aae8a97dSAneesh Kumar K.V error = -ENOENT; 41768de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41778de52778SAl Viro error = -EMLINK; 4178146a8595SJ. Bruce Fields else { 4179146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4180146a8595SJ. Bruce Fields if (!error) 41811da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4182146a8595SJ. Bruce Fields } 4183f4e0c30cSAl Viro 4184f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4185f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4186f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4187f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4188f4e0c30cSAl Viro } 41895955102cSAl Viro inode_unlock(inode); 4190e31e14ecSStephen Smalley if (!error) 41917e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41921da177e4SLinus Torvalds return error; 41931da177e4SLinus Torvalds } 41944d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41951da177e4SLinus Torvalds 41961da177e4SLinus Torvalds /* 41971da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41981da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41991da177e4SLinus Torvalds * newname. --KAB 42001da177e4SLinus Torvalds * 42011da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42021da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42031da177e4SLinus Torvalds * and other special files. --ADM 42041da177e4SLinus Torvalds */ 420546ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 420646ea89ebSDominik Brodowski const char __user *newname, int flags) 42071da177e4SLinus Torvalds { 42081da177e4SLinus Torvalds struct dentry *new_dentry; 4209dae6ad8fSAl Viro struct path old_path, new_path; 4210146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 421111a7b371SAneesh Kumar K.V int how = 0; 42121da177e4SLinus Torvalds int error; 42131da177e4SLinus Torvalds 421411a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4215c04030e1SUlrich Drepper return -EINVAL; 421611a7b371SAneesh Kumar K.V /* 4217f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4218f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4219f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 422011a7b371SAneesh Kumar K.V */ 4221f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4222f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4223f0cc6ffbSLinus Torvalds return -ENOENT; 422411a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4225f0cc6ffbSLinus Torvalds } 4226c04030e1SUlrich Drepper 422711a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 422811a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4229442e31caSJeff Layton retry: 423011a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42311da177e4SLinus Torvalds if (error) 42322ad94ae6SAl Viro return error; 42332ad94ae6SAl Viro 4234442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4235442e31caSJeff Layton (how & LOOKUP_REVAL)); 42361da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42376902d925SDave Hansen if (IS_ERR(new_dentry)) 4238dae6ad8fSAl Viro goto out; 4239dae6ad8fSAl Viro 4240dae6ad8fSAl Viro error = -EXDEV; 4241dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4242dae6ad8fSAl Viro goto out_dput; 4243800179c9SKees Cook error = may_linkat(&old_path); 4244800179c9SKees Cook if (unlikely(error)) 4245800179c9SKees Cook goto out_dput; 4246dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4247be6d3e56SKentaro Takeda if (error) 4248a8104a9fSAl Viro goto out_dput; 4249146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 425075c3f29dSDave Hansen out_dput: 4251921a1650SAl Viro done_path_create(&new_path, new_dentry); 4252146a8595SJ. Bruce Fields if (delegated_inode) { 4253146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4254d22e6338SOleg Drokin if (!error) { 4255d22e6338SOleg Drokin path_put(&old_path); 4256146a8595SJ. Bruce Fields goto retry; 4257146a8595SJ. Bruce Fields } 4258d22e6338SOleg Drokin } 4259442e31caSJeff Layton if (retry_estale(error, how)) { 4260d22e6338SOleg Drokin path_put(&old_path); 4261442e31caSJeff Layton how |= LOOKUP_REVAL; 4262442e31caSJeff Layton goto retry; 4263442e31caSJeff Layton } 42641da177e4SLinus Torvalds out: 42652d8f3038SAl Viro path_put(&old_path); 42661da177e4SLinus Torvalds 42671da177e4SLinus Torvalds return error; 42681da177e4SLinus Torvalds } 42691da177e4SLinus Torvalds 427046ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 427146ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 427246ea89ebSDominik Brodowski { 427346ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 427446ea89ebSDominik Brodowski } 427546ea89ebSDominik Brodowski 42763480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42775590ff0dSUlrich Drepper { 427846ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42795590ff0dSUlrich Drepper } 42805590ff0dSUlrich Drepper 4281bc27027aSMiklos Szeredi /** 4282bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4283bc27027aSMiklos Szeredi * @old_dir: parent of source 4284bc27027aSMiklos Szeredi * @old_dentry: source 4285bc27027aSMiklos Szeredi * @new_dir: parent of destination 4286bc27027aSMiklos Szeredi * @new_dentry: destination 4287bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4288520c8b16SMiklos Szeredi * @flags: rename flags 4289bc27027aSMiklos Szeredi * 4290bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4291bc27027aSMiklos Szeredi * 4292bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4293bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4294bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4295bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4296bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4297bc27027aSMiklos Szeredi * so. 4298bc27027aSMiklos Szeredi * 4299bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4300bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4301bc27027aSMiklos Szeredi * to be NFS exported. 4302bc27027aSMiklos Szeredi * 43031da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43041da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43051da177e4SLinus Torvalds * Problems: 43060117d427SMauro Carvalho Chehab * 4307d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43081da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43091da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4310a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43111da177e4SLinus Torvalds * story. 43126cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43136cedba89SJ. Bruce Fields * and source (if it is not a directory). 43141b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43151da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43161da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4317a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43181da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43191da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43201da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4321a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43221da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43231da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43241da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4325e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43261b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43271da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4328c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43291da177e4SLinus Torvalds * locking]. 43301da177e4SLinus Torvalds */ 43311da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43328e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4333520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43341da177e4SLinus Torvalds { 43351da177e4SLinus Torvalds int error; 4336bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4337bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4338bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4339da1ce067SMiklos Szeredi bool new_is_dir = false; 4340da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 434149d31c2fSAl Viro struct name_snapshot old_name; 43421da177e4SLinus Torvalds 43438d3e2936SMiklos Szeredi if (source == target) 43441da177e4SLinus Torvalds return 0; 43451da177e4SLinus Torvalds 43461da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43471da177e4SLinus Torvalds if (error) 43481da177e4SLinus Torvalds return error; 43491da177e4SLinus Torvalds 4350da1ce067SMiklos Szeredi if (!target) { 4351a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4352da1ce067SMiklos Szeredi } else { 4353da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4354da1ce067SMiklos Szeredi 4355da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43561da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4357da1ce067SMiklos Szeredi else 4358da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4359da1ce067SMiklos Szeredi } 43601da177e4SLinus Torvalds if (error) 43611da177e4SLinus Torvalds return error; 43621da177e4SLinus Torvalds 43632773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43641da177e4SLinus Torvalds return -EPERM; 43651da177e4SLinus Torvalds 4366bc27027aSMiklos Szeredi /* 4367bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4368bc27027aSMiklos Szeredi * we'll need to flip '..'. 4369bc27027aSMiklos Szeredi */ 4370da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4371da1ce067SMiklos Szeredi if (is_dir) { 4372bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4373bc27027aSMiklos Szeredi if (error) 4374bc27027aSMiklos Szeredi return error; 4375bc27027aSMiklos Szeredi } 4376da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4377da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4378da1ce067SMiklos Szeredi if (error) 4379da1ce067SMiklos Szeredi return error; 4380da1ce067SMiklos Szeredi } 4381da1ce067SMiklos Szeredi } 43820eeca283SRobert Love 43830b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43840b3974ebSMiklos Szeredi flags); 4385bc27027aSMiklos Szeredi if (error) 4386bc27027aSMiklos Szeredi return error; 4387bc27027aSMiklos Szeredi 438849d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4389bc27027aSMiklos Szeredi dget(new_dentry); 4390da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4391bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4392bc27027aSMiklos Szeredi else if (target) 43935955102cSAl Viro inode_lock(target); 4394bc27027aSMiklos Szeredi 4395bc27027aSMiklos Szeredi error = -EBUSY; 43967af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4397bc27027aSMiklos Szeredi goto out; 4398bc27027aSMiklos Szeredi 4399da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4400bc27027aSMiklos Szeredi error = -EMLINK; 4401da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4402bc27027aSMiklos Szeredi goto out; 4403da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4404da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4405da1ce067SMiklos Szeredi goto out; 4406da1ce067SMiklos Szeredi } 4407da1ce067SMiklos Szeredi if (!is_dir) { 4408bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4409bc27027aSMiklos Szeredi if (error) 4410bc27027aSMiklos Szeredi goto out; 4411da1ce067SMiklos Szeredi } 4412da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4413bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4414bc27027aSMiklos Szeredi if (error) 4415bc27027aSMiklos Szeredi goto out; 4416bc27027aSMiklos Szeredi } 4417520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4418520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4419bc27027aSMiklos Szeredi if (error) 4420bc27027aSMiklos Szeredi goto out; 4421bc27027aSMiklos Szeredi 4422da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44238767712fSAl Viro if (is_dir) { 44248767712fSAl Viro shrink_dcache_parent(new_dentry); 4425bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 44268767712fSAl Viro } 4427bc27027aSMiklos Szeredi dont_mount(new_dentry); 44288ed936b5SEric W. Biederman detach_mounts(new_dentry); 4429bc27027aSMiklos Szeredi } 4430da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4431da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4432bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4433da1ce067SMiklos Szeredi else 4434da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4435da1ce067SMiklos Szeredi } 4436bc27027aSMiklos Szeredi out: 4437da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4438bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4439bc27027aSMiklos Szeredi else if (target) 44405955102cSAl Viro inode_unlock(target); 4441bc27027aSMiklos Szeredi dput(new_dentry); 4442da1ce067SMiklos Szeredi if (!error) { 4443f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4444da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4445da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4446f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4447da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4448da1ce067SMiklos Szeredi } 4449da1ce067SMiklos Szeredi } 445049d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44510eeca283SRobert Love 44521da177e4SLinus Torvalds return error; 44531da177e4SLinus Torvalds } 44544d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44551da177e4SLinus Torvalds 4456ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4457ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 44581da177e4SLinus Torvalds { 44591da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44601da177e4SLinus Torvalds struct dentry *trap; 4461f5beed75SAl Viro struct path old_path, new_path; 4462f5beed75SAl Viro struct qstr old_last, new_last; 4463f5beed75SAl Viro int old_type, new_type; 44648e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 446591a27b2aSJeff Layton struct filename *from; 446691a27b2aSJeff Layton struct filename *to; 4467f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4468c6a94284SJeff Layton bool should_retry = false; 44692ad94ae6SAl Viro int error; 4470520c8b16SMiklos Szeredi 44710d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4472da1ce067SMiklos Szeredi return -EINVAL; 4473da1ce067SMiklos Szeredi 44740d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44750d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4476520c8b16SMiklos Szeredi return -EINVAL; 4477520c8b16SMiklos Szeredi 44780d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44790d7a8555SMiklos Szeredi return -EPERM; 44800d7a8555SMiklos Szeredi 4481f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4482f5beed75SAl Viro target_flags = 0; 4483f5beed75SAl Viro 4484c6a94284SJeff Layton retry: 4485c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4486c1d4dd27SAl Viro &old_path, &old_last, &old_type); 448791a27b2aSJeff Layton if (IS_ERR(from)) { 448891a27b2aSJeff Layton error = PTR_ERR(from); 44891da177e4SLinus Torvalds goto exit; 449091a27b2aSJeff Layton } 44911da177e4SLinus Torvalds 4492c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4493c1d4dd27SAl Viro &new_path, &new_last, &new_type); 449491a27b2aSJeff Layton if (IS_ERR(to)) { 449591a27b2aSJeff Layton error = PTR_ERR(to); 44961da177e4SLinus Torvalds goto exit1; 449791a27b2aSJeff Layton } 44981da177e4SLinus Torvalds 44991da177e4SLinus Torvalds error = -EXDEV; 4500f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45011da177e4SLinus Torvalds goto exit2; 45021da177e4SLinus Torvalds 45031da177e4SLinus Torvalds error = -EBUSY; 4504f5beed75SAl Viro if (old_type != LAST_NORM) 45051da177e4SLinus Torvalds goto exit2; 45061da177e4SLinus Torvalds 45070a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45080a7c3937SMiklos Szeredi error = -EEXIST; 4509f5beed75SAl Viro if (new_type != LAST_NORM) 45101da177e4SLinus Torvalds goto exit2; 45111da177e4SLinus Torvalds 4512f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4513c30dabfeSJan Kara if (error) 4514c30dabfeSJan Kara goto exit2; 4515c30dabfeSJan Kara 45168e6d782cSJ. Bruce Fields retry_deleg: 4517f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45181da177e4SLinus Torvalds 4519f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45201da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45211da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45221da177e4SLinus Torvalds goto exit3; 45231da177e4SLinus Torvalds /* source must exist */ 45241da177e4SLinus Torvalds error = -ENOENT; 4525b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45261da177e4SLinus Torvalds goto exit4; 4527f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45281da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45291da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45301da177e4SLinus Torvalds goto exit4; 45310a7c3937SMiklos Szeredi error = -EEXIST; 45320a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45330a7c3937SMiklos Szeredi goto exit5; 4534da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4535da1ce067SMiklos Szeredi error = -ENOENT; 4536da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4537da1ce067SMiklos Szeredi goto exit5; 4538da1ce067SMiklos Szeredi 4539da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4540da1ce067SMiklos Szeredi error = -ENOTDIR; 4541f5beed75SAl Viro if (new_last.name[new_last.len]) 4542da1ce067SMiklos Szeredi goto exit5; 4543da1ce067SMiklos Szeredi } 4544da1ce067SMiklos Szeredi } 45450a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45460a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45470a7c3937SMiklos Szeredi error = -ENOTDIR; 4548f5beed75SAl Viro if (old_last.name[old_last.len]) 45490a7c3937SMiklos Szeredi goto exit5; 4550f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45510a7c3937SMiklos Szeredi goto exit5; 45520a7c3937SMiklos Szeredi } 45530a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45540a7c3937SMiklos Szeredi error = -EINVAL; 45550a7c3937SMiklos Szeredi if (old_dentry == trap) 45560a7c3937SMiklos Szeredi goto exit5; 45571da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4558da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45591da177e4SLinus Torvalds error = -ENOTEMPTY; 45601da177e4SLinus Torvalds if (new_dentry == trap) 45611da177e4SLinus Torvalds goto exit5; 45621da177e4SLinus Torvalds 4563f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4564f5beed75SAl Viro &new_path, new_dentry, flags); 4565be6d3e56SKentaro Takeda if (error) 4566c30dabfeSJan Kara goto exit5; 4567f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4568f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4569520c8b16SMiklos Szeredi &delegated_inode, flags); 45701da177e4SLinus Torvalds exit5: 45711da177e4SLinus Torvalds dput(new_dentry); 45721da177e4SLinus Torvalds exit4: 45731da177e4SLinus Torvalds dput(old_dentry); 45741da177e4SLinus Torvalds exit3: 4575f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45768e6d782cSJ. Bruce Fields if (delegated_inode) { 45778e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45788e6d782cSJ. Bruce Fields if (!error) 45798e6d782cSJ. Bruce Fields goto retry_deleg; 45808e6d782cSJ. Bruce Fields } 4581f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45821da177e4SLinus Torvalds exit2: 4583c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4584c6a94284SJeff Layton should_retry = true; 4585f5beed75SAl Viro path_put(&new_path); 45862ad94ae6SAl Viro putname(to); 45871da177e4SLinus Torvalds exit1: 4588f5beed75SAl Viro path_put(&old_path); 45891da177e4SLinus Torvalds putname(from); 4590c6a94284SJeff Layton if (should_retry) { 4591c6a94284SJeff Layton should_retry = false; 4592c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4593c6a94284SJeff Layton goto retry; 4594c6a94284SJeff Layton } 45952ad94ae6SAl Viro exit: 45961da177e4SLinus Torvalds return error; 45971da177e4SLinus Torvalds } 45981da177e4SLinus Torvalds 4599ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4600ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4601ee81feb6SDominik Brodowski { 4602ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4603ee81feb6SDominik Brodowski } 4604ee81feb6SDominik Brodowski 4605520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4606520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4607520c8b16SMiklos Szeredi { 4608ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4609520c8b16SMiklos Szeredi } 4610520c8b16SMiklos Szeredi 4611a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46125590ff0dSUlrich Drepper { 4613ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46145590ff0dSUlrich Drepper } 46155590ff0dSUlrich Drepper 4616787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4617787fb6bcSMiklos Szeredi { 4618787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4619787fb6bcSMiklos Szeredi if (error) 4620787fb6bcSMiklos Szeredi return error; 4621787fb6bcSMiklos Szeredi 4622787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4623787fb6bcSMiklos Szeredi return -EPERM; 4624787fb6bcSMiklos Szeredi 4625787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4626787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4627787fb6bcSMiklos Szeredi } 4628787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4629787fb6bcSMiklos Szeredi 46305d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46311da177e4SLinus Torvalds { 46325d826c84SAl Viro int len = PTR_ERR(link); 46331da177e4SLinus Torvalds if (IS_ERR(link)) 46341da177e4SLinus Torvalds goto out; 46351da177e4SLinus Torvalds 46361da177e4SLinus Torvalds len = strlen(link); 46371da177e4SLinus Torvalds if (len > (unsigned) buflen) 46381da177e4SLinus Torvalds len = buflen; 46391da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46401da177e4SLinus Torvalds len = -EFAULT; 46411da177e4SLinus Torvalds out: 46421da177e4SLinus Torvalds return len; 46431da177e4SLinus Torvalds } 46441da177e4SLinus Torvalds 4645d60874cdSMiklos Szeredi /** 4646fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4647fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4648fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4649fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4650fd4a0edfSMiklos Szeredi * 4651fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4652fd4a0edfSMiklos Szeredi * 4653fd4a0edfSMiklos Szeredi * Does not call security hook. 4654fd4a0edfSMiklos Szeredi */ 4655fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4656fd4a0edfSMiklos Szeredi { 4657fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4658f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4659f2df5da6SAl Viro const char *link; 4660f2df5da6SAl Viro int res; 4661fd4a0edfSMiklos Szeredi 466276fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 466376fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 466476fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 466576fca90eSMiklos Szeredi 466676fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4667fd4a0edfSMiklos Szeredi return -EINVAL; 4668fd4a0edfSMiklos Szeredi 466976fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 467076fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 467176fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 467276fca90eSMiklos Szeredi } 467376fca90eSMiklos Szeredi 46744c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4675f2df5da6SAl Viro if (!link) { 4676f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4677f2df5da6SAl Viro if (IS_ERR(link)) 4678f2df5da6SAl Viro return PTR_ERR(link); 4679f2df5da6SAl Viro } 4680f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4681f2df5da6SAl Viro do_delayed_call(&done); 4682f2df5da6SAl Viro return res; 4683fd4a0edfSMiklos Szeredi } 4684fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46851da177e4SLinus Torvalds 4686d60874cdSMiklos Szeredi /** 4687d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4688d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4689d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4690d60874cdSMiklos Szeredi * 4691d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4692d60874cdSMiklos Szeredi * 4693d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4694d60874cdSMiklos Szeredi * 4695d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4696d60874cdSMiklos Szeredi */ 4697d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4698d60874cdSMiklos Szeredi { 4699d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4700d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4701d60874cdSMiklos Szeredi 4702d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4703d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4704d60874cdSMiklos Szeredi if (!res) 4705d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4706d60874cdSMiklos Szeredi } 4707d60874cdSMiklos Szeredi return res; 4708d60874cdSMiklos Szeredi } 4709d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4710d60874cdSMiklos Szeredi 47111da177e4SLinus Torvalds /* get the link contents into pagecache */ 47126b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4713fceef393SAl Viro struct delayed_call *callback) 47141da177e4SLinus Torvalds { 4715ebd09abbSDuane Griffin char *kaddr; 47161da177e4SLinus Torvalds struct page *page; 47176b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47186b255391SAl Viro 4719d3883d4fSAl Viro if (!dentry) { 4720d3883d4fSAl Viro page = find_get_page(mapping, 0); 4721d3883d4fSAl Viro if (!page) 47226b255391SAl Viro return ERR_PTR(-ECHILD); 4723d3883d4fSAl Viro if (!PageUptodate(page)) { 4724d3883d4fSAl Viro put_page(page); 4725d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4726d3883d4fSAl Viro } 4727d3883d4fSAl Viro } else { 4728090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47291da177e4SLinus Torvalds if (IS_ERR(page)) 47306fe6900eSNick Piggin return (char*)page; 4731d3883d4fSAl Viro } 4732fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 473321fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 473421fc61c7SAl Viro kaddr = page_address(page); 47356b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4736ebd09abbSDuane Griffin return kaddr; 47371da177e4SLinus Torvalds } 47381da177e4SLinus Torvalds 47396b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47401da177e4SLinus Torvalds 4741fceef393SAl Viro void page_put_link(void *arg) 47421da177e4SLinus Torvalds { 4743fceef393SAl Viro put_page(arg); 47441da177e4SLinus Torvalds } 47454d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47461da177e4SLinus Torvalds 4747aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4748aa80deabSAl Viro { 4749fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47506b255391SAl Viro int res = readlink_copy(buffer, buflen, 47516b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4752fceef393SAl Viro &done)); 4753fceef393SAl Viro do_delayed_call(&done); 4754aa80deabSAl Viro return res; 4755aa80deabSAl Viro } 4756aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4757aa80deabSAl Viro 475854566b2cSNick Piggin /* 475954566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 476054566b2cSNick Piggin */ 476154566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47621da177e4SLinus Torvalds { 47631da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47640adb25d2SKirill Korotaev struct page *page; 4765afddba49SNick Piggin void *fsdata; 4766beb497abSDmitriy Monakhov int err; 4767c718a975STetsuo Handa unsigned int flags = 0; 476854566b2cSNick Piggin if (nofs) 476954566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47701da177e4SLinus Torvalds 47717e53cac4SNeilBrown retry: 4772afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 477354566b2cSNick Piggin flags, &page, &fsdata); 47741da177e4SLinus Torvalds if (err) 4775afddba49SNick Piggin goto fail; 4776afddba49SNick Piggin 477721fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4778afddba49SNick Piggin 4779afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4780afddba49SNick Piggin page, fsdata); 47811da177e4SLinus Torvalds if (err < 0) 47821da177e4SLinus Torvalds goto fail; 4783afddba49SNick Piggin if (err < len-1) 4784afddba49SNick Piggin goto retry; 4785afddba49SNick Piggin 47861da177e4SLinus Torvalds mark_inode_dirty(inode); 47871da177e4SLinus Torvalds return 0; 47881da177e4SLinus Torvalds fail: 47891da177e4SLinus Torvalds return err; 47901da177e4SLinus Torvalds } 47914d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47921da177e4SLinus Torvalds 47930adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47940adb25d2SKirill Korotaev { 47950adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4796c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47970adb25d2SKirill Korotaev } 47984d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47990adb25d2SKirill Korotaev 480092e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48016b255391SAl Viro .get_link = page_get_link, 48021da177e4SLinus Torvalds }; 48031da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4804