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; 494ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_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; 5069883d185SAl Viro unsigned root_seq; 5079883d185SAl Viro int dfd; 5083859a271SKees Cook } __randomize_layout; 5091f55a6ecSAl Viro 5109883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 511894bc8c4SAl Viro { 512756daf26SNeilBrown struct nameidata *old = current->nameidata; 513756daf26SNeilBrown p->stack = p->internal; 514c8a53ee5SAl Viro p->dfd = dfd; 515c8a53ee5SAl Viro p->name = name; 516756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5179883d185SAl Viro p->saved = old; 518756daf26SNeilBrown current->nameidata = p; 519894bc8c4SAl Viro } 520894bc8c4SAl Viro 5219883d185SAl Viro static void restore_nameidata(void) 522894bc8c4SAl Viro { 5239883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 524756daf26SNeilBrown 525756daf26SNeilBrown current->nameidata = old; 526756daf26SNeilBrown if (old) 527756daf26SNeilBrown old->total_link_count = now->total_link_count; 528e1a63bbcSAl Viro if (now->stack != now->internal) 529756daf26SNeilBrown kfree(now->stack); 530894bc8c4SAl Viro } 531894bc8c4SAl Viro 532894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 533894bc8c4SAl Viro { 534bc40aee0SAl Viro struct saved *p; 535bc40aee0SAl Viro 536bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5376da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 538bc40aee0SAl Viro GFP_ATOMIC); 539bc40aee0SAl Viro if (unlikely(!p)) 540bc40aee0SAl Viro return -ECHILD; 541bc40aee0SAl Viro } else { 5426da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 543894bc8c4SAl Viro GFP_KERNEL); 544894bc8c4SAl Viro if (unlikely(!p)) 545894bc8c4SAl Viro return -ENOMEM; 546bc40aee0SAl Viro } 547894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 548894bc8c4SAl Viro nd->stack = p; 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro } 551894bc8c4SAl Viro 552397d425dSEric W. Biederman /** 5536b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 554397d425dSEric W. Biederman * 555397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 556397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 557397d425dSEric W. Biederman */ 5586b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 559397d425dSEric W. Biederman { 56095dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 561397d425dSEric W. Biederman 56295dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56395dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 564397d425dSEric W. Biederman return true; 565397d425dSEric W. Biederman 5666b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 567397d425dSEric W. Biederman } 568397d425dSEric W. Biederman 569894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 570894bc8c4SAl Viro { 571da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 572894bc8c4SAl Viro return 0; 573894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 574894bc8c4SAl Viro return 0; 575894bc8c4SAl Viro return __nd_alloc_stack(nd); 576894bc8c4SAl Viro } 577894bc8c4SAl Viro 5787973387aSAl Viro static void drop_links(struct nameidata *nd) 5797973387aSAl Viro { 5807973387aSAl Viro int i = nd->depth; 5817973387aSAl Viro while (i--) { 5827973387aSAl Viro struct saved *last = nd->stack + i; 583fceef393SAl Viro do_delayed_call(&last->done); 584fceef393SAl Viro clear_delayed_call(&last->done); 5857973387aSAl Viro } 5867973387aSAl Viro } 5877973387aSAl Viro 5887973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5897973387aSAl Viro { 5907973387aSAl Viro drop_links(nd); 5917973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5927973387aSAl Viro int i; 5937973387aSAl Viro path_put(&nd->path); 5947973387aSAl Viro for (i = 0; i < nd->depth; i++) 5957973387aSAl Viro path_put(&nd->stack[i].link); 59684a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 597102b8af2SAl Viro path_put(&nd->root); 59884a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 599102b8af2SAl Viro } 6007973387aSAl Viro } else { 6017973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6027973387aSAl Viro rcu_read_unlock(); 6037973387aSAl Viro } 6047973387aSAl Viro nd->depth = 0; 6057973387aSAl Viro } 6067973387aSAl Viro 6077973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6087973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6097973387aSAl Viro struct path *path, unsigned seq) 6107973387aSAl Viro { 6117973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6127973387aSAl Viro if (unlikely(res)) { 6137973387aSAl Viro if (res > 0) 6147973387aSAl Viro path->mnt = NULL; 6157973387aSAl Viro path->dentry = NULL; 6167973387aSAl Viro return false; 6177973387aSAl Viro } 6187973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6197973387aSAl Viro path->dentry = NULL; 6207973387aSAl Viro return false; 6217973387aSAl Viro } 6227973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6237973387aSAl Viro } 6247973387aSAl Viro 6257973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6267973387aSAl Viro { 6277973387aSAl Viro int i; 6287973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6297973387aSAl Viro struct saved *last = nd->stack + i; 6307973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6317973387aSAl Viro drop_links(nd); 6327973387aSAl Viro nd->depth = i + 1; 6337973387aSAl Viro return false; 6347973387aSAl Viro } 6357973387aSAl Viro } 6367973387aSAl Viro return true; 6377973387aSAl Viro } 6387973387aSAl Viro 639ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 640ee594bffSAl Viro { 641adb21d2bSAleksa Sarai /* 642adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 643adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 644adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 645adb21d2bSAleksa Sarai */ 646adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 647adb21d2bSAleksa Sarai return false; 648adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 649ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 650ee594bffSAl Viro return true; 65184a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 652ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 653ee594bffSAl Viro } 654ee594bffSAl Viro 65519660af7SAl Viro /* 65631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65957e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66431e6b01fSNick Piggin */ 66531e6b01fSNick Piggin 66631e6b01fSNick Piggin /** 66719660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66819660af7SAl Viro * @nd: nameidata pathwalk data 66939191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67031e6b01fSNick Piggin * 6714675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6724675ac39SAl Viro * for ref-walk mode. 6734675ac39SAl Viro * Must be called from rcu-walk context. 6747973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6757973387aSAl Viro * terminate_walk(). 67631e6b01fSNick Piggin */ 6774675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 67831e6b01fSNick Piggin { 67931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68031e6b01fSNick Piggin 68131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 682e5c832d5SLinus Torvalds 683e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6847973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6854675ac39SAl Viro goto out1; 68684a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 68784a2bd39SAl Viro goto out; 688ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6894675ac39SAl Viro goto out; 6904675ac39SAl Viro rcu_read_unlock(); 6914675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6924675ac39SAl Viro return 0; 6934675ac39SAl Viro 69484a2bd39SAl Viro out1: 6954675ac39SAl Viro nd->path.mnt = NULL; 6964675ac39SAl Viro nd->path.dentry = NULL; 6974675ac39SAl Viro out: 6984675ac39SAl Viro rcu_read_unlock(); 6994675ac39SAl Viro return -ECHILD; 7004675ac39SAl Viro } 7014675ac39SAl Viro 7024675ac39SAl Viro /** 7034675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7044675ac39SAl Viro * @nd: nameidata pathwalk data 7054675ac39SAl Viro * @dentry: child of nd->path.dentry 7064675ac39SAl Viro * @seq: seq number to check dentry against 7074675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7084675ac39SAl Viro * 7094675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7104675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7114675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7124675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7134675ac39SAl Viro * terminate_walk(). 7144675ac39SAl Viro */ 7154675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7164675ac39SAl Viro { 7174675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7184675ac39SAl Viro 7194675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7204675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7214675ac39SAl Viro goto out2; 7227973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7237973387aSAl Viro goto out2; 7244675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7257973387aSAl Viro goto out1; 72648a066e7SAl Viro 72715570086SLinus Torvalds /* 7284675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7294675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7304675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7314675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7324675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73315570086SLinus Torvalds */ 7344675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 735e5c832d5SLinus Torvalds goto out; 73684a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 73784a2bd39SAl Viro goto out_dput; 738e5c832d5SLinus Torvalds /* 739e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 740e5c832d5SLinus Torvalds * still valid and get it if required. 741e5c832d5SLinus Torvalds */ 74284a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74384a2bd39SAl Viro goto out_dput; 7448b61e74fSAl Viro rcu_read_unlock(); 74531e6b01fSNick Piggin return 0; 74619660af7SAl Viro 7477973387aSAl Viro out2: 7487973387aSAl Viro nd->path.mnt = NULL; 7497973387aSAl Viro out1: 7507973387aSAl Viro nd->path.dentry = NULL; 751e5c832d5SLinus Torvalds out: 7528b61e74fSAl Viro rcu_read_unlock(); 75384a2bd39SAl Viro return -ECHILD; 75484a2bd39SAl Viro out_dput: 75584a2bd39SAl Viro rcu_read_unlock(); 75684a2bd39SAl Viro dput(dentry); 75731e6b01fSNick Piggin return -ECHILD; 75831e6b01fSNick Piggin } 75931e6b01fSNick Piggin 7604ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76134286d66SNick Piggin { 762a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7634ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 764a89f8337SAl Viro else 765a89f8337SAl Viro return 1; 76634286d66SNick Piggin } 76734286d66SNick Piggin 7689f1fafeeSAl Viro /** 7699f1fafeeSAl Viro * complete_walk - successful completion of path walk 7709f1fafeeSAl Viro * @nd: pointer nameidata 77139159de2SJeff Layton * 7729f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7739f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7749f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7759f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7769f1fafeeSAl Viro * need to drop nd->path. 77739159de2SJeff Layton */ 7789f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77939159de2SJeff Layton { 78016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78139159de2SJeff Layton int status; 78239159de2SJeff Layton 7839f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 784adb21d2bSAleksa Sarai /* 785adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 786adb21d2bSAleksa Sarai * externally-managed nd->root. 787adb21d2bSAleksa Sarai */ 788adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7899f1fafeeSAl Viro nd->root.mnt = NULL; 7904675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79148a066e7SAl Viro return -ECHILD; 79248a066e7SAl Viro } 7939f1fafeeSAl Viro 794adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 795adb21d2bSAleksa Sarai /* 796adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 797adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 798adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 799adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 800adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 801adb21d2bSAleksa Sarai * 802adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 803adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 804adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 805adb21d2bSAleksa Sarai * requested root to userspace. 806adb21d2bSAleksa Sarai * 807adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 808adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 809adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 810adb21d2bSAleksa Sarai */ 811adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 812adb21d2bSAleksa Sarai return -EXDEV; 813adb21d2bSAleksa Sarai } 814adb21d2bSAleksa Sarai 81516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 81639159de2SJeff Layton return 0; 81739159de2SJeff Layton 818ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 81916c2cd71SAl Viro return 0; 82016c2cd71SAl Viro 821ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82239159de2SJeff Layton if (status > 0) 82339159de2SJeff Layton return 0; 82439159de2SJeff Layton 82516c2cd71SAl Viro if (!status) 82639159de2SJeff Layton status = -ESTALE; 82716c2cd71SAl Viro 82839159de2SJeff Layton return status; 82939159de2SJeff Layton } 83039159de2SJeff Layton 831740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8322a737871SAl Viro { 83331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8349e6697e2SAl Viro 835adb21d2bSAleksa Sarai /* 836adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 837adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 838adb21d2bSAleksa Sarai * from the dirfd. 839adb21d2bSAleksa Sarai */ 840adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 841adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 842adb21d2bSAleksa Sarai 8439e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8448f47a016SAl Viro unsigned seq; 845c28cc364SNick Piggin 846c28cc364SNick Piggin do { 847c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 84831e6b01fSNick Piggin nd->root = fs->root; 8498f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 850c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8519e6697e2SAl Viro } else { 8529e6697e2SAl Viro get_fs_root(fs, &nd->root); 85384a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8549e6697e2SAl Viro } 855740a1678SAleksa Sarai return 0; 85631e6b01fSNick Piggin } 85731e6b01fSNick Piggin 8587b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8597b9337aaSNick Piggin struct nameidata *nd) 860051d3812SIan Kent { 86131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8624ac91378SJan Blunck dput(nd->path.dentry); 86331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8644ac91378SJan Blunck mntput(nd->path.mnt); 8659a229683SHuang Shijie } 86631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8674ac91378SJan Blunck nd->path.dentry = path->dentry; 868051d3812SIan Kent } 869051d3812SIan Kent 870248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 871248fb5b9SAl Viro { 872adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 873adb21d2bSAleksa Sarai return -EXDEV; 87472ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 87572ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 87672ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 87772ba2929SAleksa Sarai return -EXDEV; 87872ba2929SAleksa Sarai } 879740a1678SAleksa Sarai if (!nd->root.mnt) { 880740a1678SAleksa Sarai int error = set_root(nd); 881740a1678SAleksa Sarai if (error) 882740a1678SAleksa Sarai return error; 883740a1678SAleksa Sarai } 884248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 885248fb5b9SAl Viro struct dentry *d; 886248fb5b9SAl Viro nd->path = nd->root; 887248fb5b9SAl Viro d = nd->path.dentry; 888248fb5b9SAl Viro nd->inode = d->d_inode; 889248fb5b9SAl Viro nd->seq = nd->root_seq; 890248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 891248fb5b9SAl Viro return -ECHILD; 892248fb5b9SAl Viro } else { 893248fb5b9SAl Viro path_put(&nd->path); 894248fb5b9SAl Viro nd->path = nd->root; 895248fb5b9SAl Viro path_get(&nd->path); 896248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 897248fb5b9SAl Viro } 898248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 899248fb5b9SAl Viro return 0; 900248fb5b9SAl Viro } 901248fb5b9SAl Viro 902b5fb63c1SChristoph Hellwig /* 9036b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 904b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 905b5fb63c1SChristoph Hellwig */ 9061bc82070SAleksa Sarai int nd_jump_link(struct path *path) 907b5fb63c1SChristoph Hellwig { 9084b99d499SAleksa Sarai int error = -ELOOP; 9096e77137bSAl Viro struct nameidata *nd = current->nameidata; 910b5fb63c1SChristoph Hellwig 9114b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9124b99d499SAleksa Sarai goto err; 9134b99d499SAleksa Sarai 91472ba2929SAleksa Sarai error = -EXDEV; 91572ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 91672ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 91772ba2929SAleksa Sarai goto err; 91872ba2929SAleksa Sarai } 919adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 920adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 921adb21d2bSAleksa Sarai goto err; 92272ba2929SAleksa Sarai 9234b99d499SAleksa Sarai path_put(&nd->path); 924b5fb63c1SChristoph Hellwig nd->path = *path; 925b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 926b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9271bc82070SAleksa Sarai return 0; 9284b99d499SAleksa Sarai 9294b99d499SAleksa Sarai err: 9304b99d499SAleksa Sarai path_put(path); 9314b99d499SAleksa Sarai return error; 932b5fb63c1SChristoph Hellwig } 933b5fb63c1SChristoph Hellwig 934b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 935574197e0SAl Viro { 93621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 937fceef393SAl Viro do_delayed_call(&last->done); 9386548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 939b9ff4429SAl Viro path_put(&last->link); 940574197e0SAl Viro } 941574197e0SAl Viro 942561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 943561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 94430aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 94530aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 946800179c9SKees Cook 947800179c9SKees Cook /** 948800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 94955852635SRandy Dunlap * @nd: nameidata pathwalk data 950800179c9SKees Cook * 951800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 952800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 953800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 954800179c9SKees Cook * processes from failing races against path names that may change out 955800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 956800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 957800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 958800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 959800179c9SKees Cook * 960800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 961800179c9SKees Cook */ 962ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 963800179c9SKees Cook { 964800179c9SKees Cook const struct inode *parent; 9652d7f9e2aSSeth Forshee kuid_t puid; 966800179c9SKees Cook 967800179c9SKees Cook if (!sysctl_protected_symlinks) 968800179c9SKees Cook return 0; 969800179c9SKees Cook 970800179c9SKees Cook /* Allowed if owner and follower match. */ 97181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 972800179c9SKees Cook return 0; 973800179c9SKees Cook 974800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 975aa65fa35SAl Viro parent = nd->inode; 976800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 977800179c9SKees Cook return 0; 978800179c9SKees Cook 979800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9802d7f9e2aSSeth Forshee puid = parent->i_uid; 9812d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 982800179c9SKees Cook return 0; 983800179c9SKees Cook 98431956502SAl Viro if (nd->flags & LOOKUP_RCU) 98531956502SAl Viro return -ECHILD; 98631956502SAl Viro 987ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 988245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 989800179c9SKees Cook return -EACCES; 990800179c9SKees Cook } 991800179c9SKees Cook 992800179c9SKees Cook /** 993800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 994800179c9SKees Cook * @inode: the source inode to hardlink from 995800179c9SKees Cook * 996800179c9SKees Cook * Return false if at least one of the following conditions: 997800179c9SKees Cook * - inode is not a regular file 998800179c9SKees Cook * - inode is setuid 999800179c9SKees Cook * - inode is setgid and group-exec 1000800179c9SKees Cook * - access failure for read and write 1001800179c9SKees Cook * 1002800179c9SKees Cook * Otherwise returns true. 1003800179c9SKees Cook */ 1004800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1005800179c9SKees Cook { 1006800179c9SKees Cook umode_t mode = inode->i_mode; 1007800179c9SKees Cook 1008800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1009800179c9SKees Cook if (!S_ISREG(mode)) 1010800179c9SKees Cook return false; 1011800179c9SKees Cook 1012800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1013800179c9SKees Cook if (mode & S_ISUID) 1014800179c9SKees Cook return false; 1015800179c9SKees Cook 1016800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1017800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1018800179c9SKees Cook return false; 1019800179c9SKees Cook 1020800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1021800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1022800179c9SKees Cook return false; 1023800179c9SKees Cook 1024800179c9SKees Cook return true; 1025800179c9SKees Cook } 1026800179c9SKees Cook 1027800179c9SKees Cook /** 1028800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1029800179c9SKees Cook * @link: the source to hardlink from 1030800179c9SKees Cook * 1031800179c9SKees Cook * Block hardlink when all of: 1032800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1033800179c9SKees Cook * - fsuid does not match inode 1034800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1035f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1036800179c9SKees Cook * 1037800179c9SKees Cook * Returns 0 if successful, -ve on error. 1038800179c9SKees Cook */ 1039800179c9SKees Cook static int may_linkat(struct path *link) 1040800179c9SKees Cook { 1041593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1042593d1ce8SEric W. Biederman 1043593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1044593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1045593d1ce8SEric W. Biederman return -EOVERFLOW; 1046800179c9SKees Cook 1047800179c9SKees Cook if (!sysctl_protected_hardlinks) 1048800179c9SKees Cook return 0; 1049800179c9SKees Cook 1050800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1051800179c9SKees Cook * otherwise, it must be a safe source. 1052800179c9SKees Cook */ 1053cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1054800179c9SKees Cook return 0; 1055800179c9SKees Cook 1056245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1057800179c9SKees Cook return -EPERM; 1058800179c9SKees Cook } 1059800179c9SKees Cook 106030aba665SSalvatore Mesoraca /** 106130aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 106230aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 106330aba665SSalvatore Mesoraca * exist. 1064d0cb5018SAl Viro * @dir_mode: mode bits of directory 1065d0cb5018SAl Viro * @dir_uid: owner of directory 106630aba665SSalvatore Mesoraca * @inode: the inode of the file to open 106730aba665SSalvatore Mesoraca * 106830aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 106930aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 107030aba665SSalvatore Mesoraca * - the file already exists 107130aba665SSalvatore Mesoraca * - we are in a sticky directory 107230aba665SSalvatore Mesoraca * - we don't own the file 107330aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 107430aba665SSalvatore Mesoraca * - the directory is world writable 107530aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 107630aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 107730aba665SSalvatore Mesoraca * be enough. 107830aba665SSalvatore Mesoraca * 107930aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 108030aba665SSalvatore Mesoraca */ 1081d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 108230aba665SSalvatore Mesoraca struct inode * const inode) 108330aba665SSalvatore Mesoraca { 108430aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 108530aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1086d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1087d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 108830aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 108930aba665SSalvatore Mesoraca return 0; 109030aba665SSalvatore Mesoraca 1091d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1092d0cb5018SAl Viro (dir_mode & 0020 && 109330aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 109430aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1095245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1096245d7369SKees Cook "sticky_create_fifo" : 1097245d7369SKees Cook "sticky_create_regular"; 1098245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 109930aba665SSalvatore Mesoraca return -EACCES; 110030aba665SSalvatore Mesoraca } 110130aba665SSalvatore Mesoraca return 0; 110230aba665SSalvatore Mesoraca } 110330aba665SSalvatore Mesoraca 1104f015f126SDavid Howells /* 1105f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1106f015f126SDavid Howells * 1107f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1108f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1109f015f126SDavid Howells * Up is towards /. 1110f015f126SDavid Howells * 1111f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1112f015f126SDavid Howells * root. 1113f015f126SDavid Howells */ 1114bab77ebfSAl Viro int follow_up(struct path *path) 11151da177e4SLinus Torvalds { 11160714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11170714a533SAl Viro struct mount *parent; 11181da177e4SLinus Torvalds struct dentry *mountpoint; 111999b7db7bSNick Piggin 112048a066e7SAl Viro read_seqlock_excl(&mount_lock); 11210714a533SAl Viro parent = mnt->mnt_parent; 11223c0a6163SAl Viro if (parent == mnt) { 112348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11241da177e4SLinus Torvalds return 0; 11251da177e4SLinus Torvalds } 11260714a533SAl Viro mntget(&parent->mnt); 1127a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 112848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1129bab77ebfSAl Viro dput(path->dentry); 1130bab77ebfSAl Viro path->dentry = mountpoint; 1131bab77ebfSAl Viro mntput(path->mnt); 11320714a533SAl Viro path->mnt = &parent->mnt; 11331da177e4SLinus Torvalds return 1; 11341da177e4SLinus Torvalds } 11354d359507SAl Viro EXPORT_SYMBOL(follow_up); 11361da177e4SLinus Torvalds 1137b5c84bf6SNick Piggin /* 11389875cf80SDavid Howells * Perform an automount 11399875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11409875cf80SDavid Howells * were called with. 11411da177e4SLinus Torvalds */ 11421c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 114331e6b01fSNick Piggin { 114425e195aaSAl Viro struct dentry *dentry = path->dentry; 11459875cf80SDavid Howells 11460ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11470ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11480ec26fd0SMiklos Szeredi * the name. 11490ec26fd0SMiklos Szeredi * 11500ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11515a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11520ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11530ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11540ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11550ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11565a30d8a2SDavid Howells */ 11571c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11585d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 115925e195aaSAl Viro dentry->d_inode) 11609875cf80SDavid Howells return -EISDIR; 11610ec26fd0SMiklos Szeredi 11621c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 11639875cf80SDavid Howells return -ELOOP; 11649875cf80SDavid Howells 116525e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1166ea5b778aSDavid Howells } 11679875cf80SDavid Howells 11689875cf80SDavid Howells /* 11699deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 11709deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 11719deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 11729deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 11739875cf80SDavid Howells */ 11749deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 11759deed3ebSAl Viro int *count, unsigned lookup_flags) 11769875cf80SDavid Howells { 11779deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 11789875cf80SDavid Howells bool need_mntput = false; 11798aef1884SAl Viro int ret = 0; 11809875cf80SDavid Howells 11819deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1182cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1183cc53ce53SDavid Howells * being held. */ 1184d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1185fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1186508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1187cc53ce53SDavid Howells if (ret < 0) 11888aef1884SAl Viro break; 1189cc53ce53SDavid Howells } 1190cc53ce53SDavid Howells 11919deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 11929875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11939deed3ebSAl Viro if (mounted) { // ... in our namespace 11949875cf80SDavid Howells dput(path->dentry); 11959875cf80SDavid Howells if (need_mntput) 1196463ffb2eSAl Viro mntput(path->mnt); 1197463ffb2eSAl Viro path->mnt = mounted; 1198463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11999deed3ebSAl Viro // here we know it's positive 12009deed3ebSAl Viro flags = path->dentry->d_flags; 12019875cf80SDavid Howells need_mntput = true; 12029875cf80SDavid Howells continue; 1203463ffb2eSAl Viro } 12041da177e4SLinus Torvalds } 12059875cf80SDavid Howells 12069deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 12079deed3ebSAl Viro break; 12089deed3ebSAl Viro 12099deed3ebSAl Viro // uncovered automount point 12109deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 12119deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 12129875cf80SDavid Howells if (ret < 0) 12138aef1884SAl Viro break; 12149875cf80SDavid Howells } 12159875cf80SDavid Howells 12169deed3ebSAl Viro if (ret == -EISDIR) 12179deed3ebSAl Viro ret = 0; 12189deed3ebSAl Viro // possible if you race with several mount --move 12199deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 12208aef1884SAl Viro mntput(path->mnt); 12219deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1222d41efb52SAl Viro ret = -ENOENT; 12239deed3ebSAl Viro *jumped = need_mntput; 12248402752eSAl Viro return ret; 12251da177e4SLinus Torvalds } 12261da177e4SLinus Torvalds 12279deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 12289deed3ebSAl Viro int *count, unsigned lookup_flags) 12299deed3ebSAl Viro { 12309deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 12319deed3ebSAl Viro 12329deed3ebSAl Viro /* fastpath */ 12339deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 12349deed3ebSAl Viro *jumped = false; 12359deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 12369deed3ebSAl Viro return -ENOENT; 12379deed3ebSAl Viro return 0; 12389deed3ebSAl Viro } 12399deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 12409deed3ebSAl Viro } 12419deed3ebSAl Viro 1242cc53ce53SDavid Howells int follow_down_one(struct path *path) 12431da177e4SLinus Torvalds { 12441da177e4SLinus Torvalds struct vfsmount *mounted; 12451da177e4SLinus Torvalds 12461c755af4SAl Viro mounted = lookup_mnt(path); 12471da177e4SLinus Torvalds if (mounted) { 12489393bd07SAl Viro dput(path->dentry); 12499393bd07SAl Viro mntput(path->mnt); 12509393bd07SAl Viro path->mnt = mounted; 12519393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12521da177e4SLinus Torvalds return 1; 12531da177e4SLinus Torvalds } 12541da177e4SLinus Torvalds return 0; 12551da177e4SLinus Torvalds } 12564d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12571da177e4SLinus Torvalds 12589875cf80SDavid Howells /* 12599deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 12609deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 12619deed3ebSAl Viro * caller is permitted to proceed or not. 12629deed3ebSAl Viro */ 12639deed3ebSAl Viro int follow_down(struct path *path) 12649deed3ebSAl Viro { 12659deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 12669deed3ebSAl Viro bool jumped; 12679deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 12689deed3ebSAl Viro 12699deed3ebSAl Viro if (path->mnt != mnt) 12709deed3ebSAl Viro mntput(mnt); 12719deed3ebSAl Viro return ret; 12729deed3ebSAl Viro } 12739deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 12749deed3ebSAl Viro 12759deed3ebSAl Viro /* 1276287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1277287548e4SAl Viro * we meet a managed dentry that would need blocking. 12789875cf80SDavid Howells */ 12799875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1280254cf582SAl Viro struct inode **inode, unsigned *seqp) 12819875cf80SDavid Howells { 1282ea936aebSAl Viro struct dentry *dentry = path->dentry; 1283ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1284ea936aebSAl Viro 1285ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1286ea936aebSAl Viro return true; 1287ea936aebSAl Viro 1288ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1289ea936aebSAl Viro return false; 1290ea936aebSAl Viro 129162a7375eSIan Kent for (;;) { 129262a7375eSIan Kent /* 129362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 129462a7375eSIan Kent * that wants to block transit. 129562a7375eSIan Kent */ 1296ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1297ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1298ea936aebSAl Viro if (res) 1299ea936aebSAl Viro return res == -EISDIR; 1300ea936aebSAl Viro flags = dentry->d_flags; 1301b8faf035SNeilBrown } 130262a7375eSIan Kent 1303ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1304ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1305ea936aebSAl Viro if (mounted) { 1306c7105365SAl Viro path->mnt = &mounted->mnt; 1307ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1308a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1309ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1310ea936aebSAl Viro *inode = dentry->d_inode; 131159430262SLinus Torvalds /* 1312ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1313ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1314ea936aebSAl Viro * between mount hash removal and ->mnt_root 1315ea936aebSAl Viro * becoming unpinned. 131659430262SLinus Torvalds */ 1317ea936aebSAl Viro flags = dentry->d_flags; 1318ea936aebSAl Viro continue; 13199875cf80SDavid Howells } 1320ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1321ea936aebSAl Viro return false; 1322ea936aebSAl Viro } 1323ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1324ea936aebSAl Viro } 1325287548e4SAl Viro } 1326287548e4SAl Viro 1327db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1328db3c9adeSAl Viro struct path *path, struct inode **inode, 1329db3c9adeSAl Viro unsigned int *seqp) 1330bd7c4b50SAl Viro { 13319deed3ebSAl Viro bool jumped; 1332db3c9adeSAl Viro int ret; 1333bd7c4b50SAl Viro 1334db3c9adeSAl Viro path->mnt = nd->path.mnt; 1335db3c9adeSAl Viro path->dentry = dentry; 1336c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1337c153007bSAl Viro unsigned int seq = *seqp; 1338c153007bSAl Viro if (unlikely(!*inode)) 1339c153007bSAl Viro return -ENOENT; 1340c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 13419deed3ebSAl Viro return 0; 1342c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1343c153007bSAl Viro return -ECHILD; 1344c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1345c153007bSAl Viro path->mnt = nd->path.mnt; 1346c153007bSAl Viro path->dentry = dentry; 1347c153007bSAl Viro } 13489deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 13499deed3ebSAl Viro if (jumped) { 13509deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 13519deed3ebSAl Viro ret = -EXDEV; 13529deed3ebSAl Viro else 13539deed3ebSAl Viro nd->flags |= LOOKUP_JUMPED; 13549deed3ebSAl Viro } 13559deed3ebSAl Viro if (unlikely(ret)) { 13569deed3ebSAl Viro dput(path->dentry); 13579deed3ebSAl Viro if (path->mnt != nd->path.mnt) 13589deed3ebSAl Viro mntput(path->mnt); 13599deed3ebSAl Viro } else { 1360bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1361bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1362bd7c4b50SAl Viro } 1363bd7c4b50SAl Viro return ret; 1364bd7c4b50SAl Viro } 1365bd7c4b50SAl Viro 13669875cf80SDavid Howells /* 13679875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 13689875cf80SDavid Howells */ 13699875cf80SDavid Howells static void follow_mount(struct path *path) 13709875cf80SDavid Howells { 13719875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 13729875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13739875cf80SDavid Howells if (!mounted) 13749875cf80SDavid Howells break; 13759875cf80SDavid Howells dput(path->dentry); 13769875cf80SDavid Howells mntput(path->mnt); 13779875cf80SDavid Howells path->mnt = mounted; 13789875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13799875cf80SDavid Howells } 13809875cf80SDavid Howells } 13819875cf80SDavid Howells 13821da177e4SLinus Torvalds /* 1383f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1384f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1385baa03890SNick Piggin */ 1386e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1387e3c13928SAl Viro struct dentry *dir, 13886c51e513SAl Viro unsigned int flags) 1389baa03890SNick Piggin { 1390a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1391bad61189SMiklos Szeredi if (dentry) { 1392a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1393bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 139474ff0ffcSAl Viro if (!error) 13955542aa2fSEric W. Biederman d_invalidate(dentry); 1396bad61189SMiklos Szeredi dput(dentry); 139774ff0ffcSAl Viro return ERR_PTR(error); 1398bad61189SMiklos Szeredi } 1399bad61189SMiklos Szeredi } 1400baa03890SNick Piggin return dentry; 1401baa03890SNick Piggin } 1402baa03890SNick Piggin 1403baa03890SNick Piggin /* 1404a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1405a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1406a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1407a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1408a03ece5fSAl Viro * at all. 140944396f4bSJosef Bacik */ 1410a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1411a03ece5fSAl Viro struct dentry *base, unsigned int flags) 141244396f4bSJosef Bacik { 1413a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 141444396f4bSJosef Bacik struct dentry *old; 1415a03ece5fSAl Viro struct inode *dir = base->d_inode; 1416a03ece5fSAl Viro 1417a03ece5fSAl Viro if (dentry) 1418a03ece5fSAl Viro return dentry; 141944396f4bSJosef Bacik 142044396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1421a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 142244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1423a03ece5fSAl Viro 1424a03ece5fSAl Viro dentry = d_alloc(base, name); 1425a03ece5fSAl Viro if (unlikely(!dentry)) 1426a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 142744396f4bSJosef Bacik 142872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 142944396f4bSJosef Bacik if (unlikely(old)) { 143044396f4bSJosef Bacik dput(dentry); 143144396f4bSJosef Bacik dentry = old; 143244396f4bSJosef Bacik } 143344396f4bSJosef Bacik return dentry; 143444396f4bSJosef Bacik } 143544396f4bSJosef Bacik 143620e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 143720e34357SAl Viro struct inode **inode, 1438254cf582SAl Viro unsigned *seqp) 14391da177e4SLinus Torvalds { 144031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14415a18fff2SAl Viro int status = 1; 14429875cf80SDavid Howells 14433cac260aSAl Viro /* 1444b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 14455d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 14465d0f49c1SAl Viro * going to fall back to non-racy lookup. 1447b04f784eSNick Piggin */ 144831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 144931e6b01fSNick Piggin unsigned seq; 1450da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14515d0f49c1SAl Viro if (unlikely(!dentry)) { 14524675ac39SAl Viro if (unlazy_walk(nd)) 145320e34357SAl Viro return ERR_PTR(-ECHILD); 145420e34357SAl Viro return NULL; 14555d0f49c1SAl Viro } 14565a18fff2SAl Viro 145712f8ad4bSLinus Torvalds /* 145812f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 145912f8ad4bSLinus Torvalds * the dentry name information from lookup. 146012f8ad4bSLinus Torvalds */ 146163afdfc7SDavid Howells *inode = d_backing_inode(dentry); 14625d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 146320e34357SAl Viro return ERR_PTR(-ECHILD); 146412f8ad4bSLinus Torvalds 146512f8ad4bSLinus Torvalds /* 146612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 146712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 146812f8ad4bSLinus Torvalds * 146912f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 147012f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 147112f8ad4bSLinus Torvalds */ 14725d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 147320e34357SAl Viro return ERR_PTR(-ECHILD); 14745a18fff2SAl Viro 1475254cf582SAl Viro *seqp = seq; 14764ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1477c153007bSAl Viro if (likely(status > 0)) 147820e34357SAl Viro return dentry; 14794675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 148020e34357SAl Viro return ERR_PTR(-ECHILD); 1481209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1482209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1483209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 14845a18fff2SAl Viro } else { 1485e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 148681e6f520SAl Viro if (unlikely(!dentry)) 148720e34357SAl Viro return NULL; 14884ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14895d0f49c1SAl Viro } 14905a18fff2SAl Viro if (unlikely(status <= 0)) { 1491e9742b53SAl Viro if (!status) 14925d0f49c1SAl Viro d_invalidate(dentry); 14935a18fff2SAl Viro dput(dentry); 149420e34357SAl Viro return ERR_PTR(status); 14955a18fff2SAl Viro } 149620e34357SAl Viro return dentry; 1497697f514dSMiklos Szeredi } 1498697f514dSMiklos Szeredi 1499697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 150088d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1501e3c13928SAl Viro struct dentry *dir, 1502e3c13928SAl Viro unsigned int flags) 1503697f514dSMiklos Szeredi { 150488d8331aSAl Viro struct dentry *dentry, *old; 15051936386eSAl Viro struct inode *inode = dir->d_inode; 1506d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15071936386eSAl Viro 15081936386eSAl Viro /* Don't go there if it's already dead */ 150994bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 151088d8331aSAl Viro return ERR_PTR(-ENOENT); 151194bdd655SAl Viro again: 1512d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 151394bdd655SAl Viro if (IS_ERR(dentry)) 151488d8331aSAl Viro return dentry; 151594bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1516949a852eSAl Viro int error = d_revalidate(dentry, flags); 1517949a852eSAl Viro if (unlikely(error <= 0)) { 151894bdd655SAl Viro if (!error) { 1519949a852eSAl Viro d_invalidate(dentry); 1520949a852eSAl Viro dput(dentry); 152194bdd655SAl Viro goto again; 152294bdd655SAl Viro } 152394bdd655SAl Viro dput(dentry); 1524949a852eSAl Viro dentry = ERR_PTR(error); 1525949a852eSAl Viro } 152694bdd655SAl Viro } else { 15271936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 152885c7f810SAl Viro d_lookup_done(dentry); 15291936386eSAl Viro if (unlikely(old)) { 15301936386eSAl Viro dput(dentry); 15311936386eSAl Viro dentry = old; 1532949a852eSAl Viro } 1533949a852eSAl Viro } 1534e3c13928SAl Viro return dentry; 15351da177e4SLinus Torvalds } 15361da177e4SLinus Torvalds 153788d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 153888d8331aSAl Viro struct dentry *dir, 153988d8331aSAl Viro unsigned int flags) 154088d8331aSAl Viro { 154188d8331aSAl Viro struct inode *inode = dir->d_inode; 154288d8331aSAl Viro struct dentry *res; 154388d8331aSAl Viro inode_lock_shared(inode); 154488d8331aSAl Viro res = __lookup_slow(name, dir, flags); 154588d8331aSAl Viro inode_unlock_shared(inode); 154688d8331aSAl Viro return res; 154788d8331aSAl Viro } 154888d8331aSAl Viro 154952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 155052094c8aSAl Viro { 155152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15524ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 155352094c8aSAl Viro if (err != -ECHILD) 155452094c8aSAl Viro return err; 15554675ac39SAl Viro if (unlazy_walk(nd)) 155652094c8aSAl Viro return -ECHILD; 155752094c8aSAl Viro } 15584ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 155952094c8aSAl Viro } 156052094c8aSAl Viro 1561b1a81972SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 1562b1a81972SAl Viro 156306708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1564b1a81972SAl Viro struct inode *inode, unsigned seq, int flags) 1565d63ff28fSAl Viro { 15661cf2665bSAl Viro struct saved *last; 1567ad6cc4c3SAl Viro const char *res; 1568ad6cc4c3SAl Viro int error; 1569ad6cc4c3SAl Viro 1570756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1571626de996SAl Viro path_to_nameidata(link, nd); 157206708adbSAl Viro return ERR_PTR(-ELOOP); 1573626de996SAl Viro } 1574bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1575cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1576cd179f44SAl Viro mntget(link->mnt); 15777973387aSAl Viro } 1578626de996SAl Viro error = nd_alloc_stack(nd); 1579626de996SAl Viro if (unlikely(error)) { 1580bc40aee0SAl Viro if (error == -ECHILD) { 1581ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1582ad1633a1SAl Viro drop_links(nd); 1583ad1633a1SAl Viro nd->depth = 0; 1584ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1585ad1633a1SAl Viro nd->path.mnt = NULL; 1586ad1633a1SAl Viro nd->path.dentry = NULL; 1587ad1633a1SAl Viro rcu_read_unlock(); 15884675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1589bc40aee0SAl Viro error = nd_alloc_stack(nd); 1590bc40aee0SAl Viro } 1591bc40aee0SAl Viro if (error) { 1592cd179f44SAl Viro path_put(link); 159306708adbSAl Viro return ERR_PTR(error); 1594626de996SAl Viro } 1595bc40aee0SAl Viro } 1596626de996SAl Viro 1597ab104923SAl Viro last = nd->stack + nd->depth++; 15981cf2665bSAl Viro last->link = *link; 1599fceef393SAl Viro clear_delayed_call(&last->done); 16000450b2d1SAl Viro last->seq = seq; 1601ad6cc4c3SAl Viro 1602b1a81972SAl Viro if (flags & WALK_TRAILING) { 1603ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1604ad6cc4c3SAl Viro if (unlikely(error)) 1605ad6cc4c3SAl Viro return ERR_PTR(error); 1606ad6cc4c3SAl Viro } 1607ad6cc4c3SAl Viro 1608ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1609ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1610ad6cc4c3SAl Viro 1611ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1612ad6cc4c3SAl Viro touch_atime(&last->link); 1613ad6cc4c3SAl Viro cond_resched(); 1614ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1615ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1616ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1617ad6cc4c3SAl Viro touch_atime(&last->link); 1618ad6cc4c3SAl Viro } 1619ad6cc4c3SAl Viro 1620ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1621ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1622ad6cc4c3SAl Viro if (unlikely(error)) 1623ad6cc4c3SAl Viro return ERR_PTR(error); 1624ad6cc4c3SAl Viro 1625ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1626ad6cc4c3SAl Viro if (!res) { 1627ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1628ad6cc4c3SAl Viro struct delayed_call *); 1629ad6cc4c3SAl Viro get = inode->i_op->get_link; 1630ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1631ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1632ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1633ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1634ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1635ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1636ad6cc4c3SAl Viro } 1637ad6cc4c3SAl Viro } else { 1638ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1639ad6cc4c3SAl Viro } 1640ad6cc4c3SAl Viro if (!res) 1641ad6cc4c3SAl Viro goto all_done; 1642ad6cc4c3SAl Viro if (IS_ERR(res)) 1643ad6cc4c3SAl Viro return res; 1644ad6cc4c3SAl Viro } 1645ad6cc4c3SAl Viro if (*res == '/') { 1646ad6cc4c3SAl Viro error = nd_jump_root(nd); 1647ad6cc4c3SAl Viro if (unlikely(error)) 1648ad6cc4c3SAl Viro return ERR_PTR(error); 1649ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1650ad6cc4c3SAl Viro ; 1651ad6cc4c3SAl Viro } 1652ad6cc4c3SAl Viro if (*res) 1653ad6cc4c3SAl Viro return res; 1654ad6cc4c3SAl Viro all_done: // pure jump 1655ad6cc4c3SAl Viro put_link(nd); 1656ad6cc4c3SAl Viro return NULL; 1657d63ff28fSAl Viro } 1658d63ff28fSAl Viro 16593ddcd056SLinus Torvalds /* 16603ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16613ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16623ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16633ddcd056SLinus Torvalds * for the common case. 16643ddcd056SLinus Torvalds */ 1665b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1666cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 16673ddcd056SLinus Torvalds { 1668cbae4d12SAl Viro struct path path; 1669cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1670cbae4d12SAl Viro 1671cbae4d12SAl Viro if (err < 0) 1672b0417d2cSAl Viro return ERR_PTR(err); 1673cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 16748c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1675aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 16768f64fb1cSAl Viro /* not a symlink or should not follow */ 1677cbae4d12SAl Viro path_to_nameidata(&path, nd); 16788f64fb1cSAl Viro nd->inode = inode; 16798f64fb1cSAl Viro nd->seq = seq; 1680b0417d2cSAl Viro return NULL; 16818f64fb1cSAl Viro } 1682a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1683a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1684cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1685b0417d2cSAl Viro return ERR_PTR(-ECHILD); 1686a7f77542SAl Viro } 1687b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 16883ddcd056SLinus Torvalds } 16893ddcd056SLinus Torvalds 1690c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1691c2df1968SAl Viro struct inode **inodep, 1692c2df1968SAl Viro unsigned *seqp) 1693957dd41dSAl Viro { 1694957dd41dSAl Viro while (1) { 1695957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 1696957dd41dSAl Viro break; 1697957dd41dSAl Viro if (nd->path.dentry != nd->path.mnt->mnt_root) { 1698957dd41dSAl Viro struct dentry *old = nd->path.dentry; 1699c2df1968SAl Viro struct dentry *parent = old->d_parent; 1700957dd41dSAl Viro 1701c2df1968SAl Viro *inodep = parent->d_inode; 1702c2df1968SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 1703957dd41dSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 17047521f22bSAl Viro return ERR_PTR(-ECHILD); 1705957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 17067521f22bSAl Viro return ERR_PTR(-ECHILD); 1707c2df1968SAl Viro return parent; 1708957dd41dSAl Viro } else { 1709957dd41dSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1710957dd41dSAl Viro struct mount *mparent = mnt->mnt_parent; 1711957dd41dSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1712c2df1968SAl Viro struct inode *inode = mountpoint->d_inode; 1713957dd41dSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1714957dd41dSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 17157521f22bSAl Viro return ERR_PTR(-ECHILD); 1716957dd41dSAl Viro if (&mparent->mnt == nd->path.mnt) 1717957dd41dSAl Viro break; 1718957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 17197521f22bSAl Viro return ERR_PTR(-ECHILD); 1720957dd41dSAl Viro /* we know that mountpoint was pinned */ 1721957dd41dSAl Viro nd->path.dentry = mountpoint; 1722957dd41dSAl Viro nd->path.mnt = &mparent->mnt; 1723c2df1968SAl Viro nd->inode = inode; 1724957dd41dSAl Viro nd->seq = seq; 1725957dd41dSAl Viro } 1726957dd41dSAl Viro } 1727957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17287521f22bSAl Viro return ERR_PTR(-ECHILD); 1729c2df1968SAl Viro return NULL; 1730957dd41dSAl Viro } 1731957dd41dSAl Viro 1732c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1733c2df1968SAl Viro struct inode **inodep, 1734c2df1968SAl Viro unsigned *seqp) 1735957dd41dSAl Viro { 1736957dd41dSAl Viro while (1) { 1737957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 1738957dd41dSAl Viro break; 1739957dd41dSAl Viro if (nd->path.dentry != nd->path.mnt->mnt_root) { 1740957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 1741c2df1968SAl Viro struct dentry *parent = dget_parent(nd->path.dentry); 1742957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1743957dd41dSAl Viro dput(parent); 17447521f22bSAl Viro return ERR_PTR(-ENOENT); 1745957dd41dSAl Viro } 1746c2df1968SAl Viro *seqp = 0; 1747c2df1968SAl Viro *inodep = parent->d_inode; 1748c2df1968SAl Viro return parent; 1749957dd41dSAl Viro } 1750957dd41dSAl Viro if (!follow_up(&nd->path)) 1751957dd41dSAl Viro break; 1752957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 17537521f22bSAl Viro return ERR_PTR(-EXDEV); 1754957dd41dSAl Viro } 1755957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17567521f22bSAl Viro return ERR_PTR(-EXDEV); 1757c2df1968SAl Viro dget(nd->path.dentry); 1758c2df1968SAl Viro return NULL; 1759957dd41dSAl Viro } 1760957dd41dSAl Viro 17617521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1762957dd41dSAl Viro { 1763957dd41dSAl Viro if (type == LAST_DOTDOT) { 17647521f22bSAl Viro const char *error = NULL; 1765c2df1968SAl Viro struct dentry *parent; 1766c2df1968SAl Viro struct inode *inode; 1767c2df1968SAl Viro unsigned seq; 1768957dd41dSAl Viro 1769957dd41dSAl Viro if (!nd->root.mnt) { 17707521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1771957dd41dSAl Viro if (error) 1772957dd41dSAl Viro return error; 1773957dd41dSAl Viro } 1774957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1775c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1776957dd41dSAl Viro else 1777c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1778c2df1968SAl Viro if (IS_ERR(parent)) 1779c2df1968SAl Viro return ERR_CAST(parent); 1780c2df1968SAl Viro if (unlikely(!parent)) 1781c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1782c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1783c2df1968SAl Viro else 1784c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1785c2df1968SAl Viro parent, inode, seq); 1786c2df1968SAl Viro if (unlikely(error)) 1787957dd41dSAl Viro return error; 1788957dd41dSAl Viro 1789957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1790957dd41dSAl Viro /* 1791957dd41dSAl Viro * If there was a racing rename or mount along our 1792957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1793957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1794957dd41dSAl Viro * some fallback). 1795957dd41dSAl Viro */ 1796957dd41dSAl Viro smp_rmb(); 1797957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 17987521f22bSAl Viro return ERR_PTR(-EAGAIN); 1799957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 18007521f22bSAl Viro return ERR_PTR(-EAGAIN); 1801957dd41dSAl Viro } 1802957dd41dSAl Viro } 18037521f22bSAl Viro return NULL; 1804957dd41dSAl Viro } 1805957dd41dSAl Viro 180692d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1807ce57dfc1SAl Viro { 1808db3c9adeSAl Viro struct dentry *dentry; 1809ce57dfc1SAl Viro struct inode *inode; 1810254cf582SAl Viro unsigned seq; 1811ce57dfc1SAl Viro /* 1812ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1813ce57dfc1SAl Viro * to be able to know about the current root directory and 1814ce57dfc1SAl Viro * parent relationships. 1815ce57dfc1SAl Viro */ 18164693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18171c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18184693a547SAl Viro put_link(nd); 18197521f22bSAl Viro return handle_dots(nd, nd->last_type); 18204693a547SAl Viro } 182120e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 182220e34357SAl Viro if (IS_ERR(dentry)) 182392d27016SAl Viro return ERR_CAST(dentry); 182420e34357SAl Viro if (unlikely(!dentry)) { 1825db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1826db3c9adeSAl Viro if (IS_ERR(dentry)) 182792d27016SAl Viro return ERR_CAST(dentry); 182820e34357SAl Viro } 182956676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 183056676ec3SAl Viro put_link(nd); 1831b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1832ce57dfc1SAl Viro } 1833ce57dfc1SAl Viro 18341da177e4SLinus Torvalds /* 1835bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1836bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1837bfcfaa77SLinus Torvalds * 1838bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1839bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1840bfcfaa77SLinus Torvalds * fast. 1841bfcfaa77SLinus Torvalds * 1842bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1843bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1844bfcfaa77SLinus Torvalds * crossing operation. 1845bfcfaa77SLinus Torvalds * 1846bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1847bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1848bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1849bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1850bfcfaa77SLinus Torvalds */ 1851bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1852bfcfaa77SLinus Torvalds 1853f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1854bfcfaa77SLinus Torvalds 1855468a9428SGeorge Spelvin #ifdef HASH_MIX 1856bfcfaa77SLinus Torvalds 1857468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1858468a9428SGeorge Spelvin 1859468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18602a18da7aSGeorge Spelvin /* 18612a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18622a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18632a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18642a18da7aSGeorge Spelvin * and no temporaries. 18652a18da7aSGeorge Spelvin * 18662a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18672a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18682a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18692a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18702a18da7aSGeorge Spelvin * 18712a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18722a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18732a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18742a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18752a18da7aSGeorge Spelvin * 18762a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18772a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18782a18da7aSGeorge Spelvin * toggling any given output bit. 18792a18da7aSGeorge Spelvin * 18802a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18812a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18822a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18832a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18842a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18852a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18862a18da7aSGeorge Spelvin * Perfect: 8192 258048 18872a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18882a18da7aSGeorge Spelvin */ 18892a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18902a18da7aSGeorge Spelvin ( x ^= (a), \ 18912a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18922a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18932a18da7aSGeorge Spelvin y *= 9 ) 1894bfcfaa77SLinus Torvalds 18950fed3ac8SGeorge Spelvin /* 18962a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18972a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18982a18da7aSGeorge Spelvin * work done before the hash value is used. 18990fed3ac8SGeorge Spelvin */ 19002a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19010fed3ac8SGeorge Spelvin { 19022a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19032a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19042a18da7aSGeorge Spelvin return y >> 32; 19050fed3ac8SGeorge Spelvin } 19060fed3ac8SGeorge Spelvin 1907bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1908bfcfaa77SLinus Torvalds 19092a18da7aSGeorge Spelvin /* 19102a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19112a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19122a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19132a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19142a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19152a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19162a18da7aSGeorge Spelvin * Perfect: 2048 31744 19172a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19182a18da7aSGeorge Spelvin */ 19192a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19202a18da7aSGeorge Spelvin ( x ^= (a), \ 19212a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19222a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19232a18da7aSGeorge Spelvin y *= 9 ) 1924bfcfaa77SLinus Torvalds 19252a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19260fed3ac8SGeorge Spelvin { 19272a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19282a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19290fed3ac8SGeorge Spelvin } 19300fed3ac8SGeorge Spelvin 1931bfcfaa77SLinus Torvalds #endif 1932bfcfaa77SLinus Torvalds 19332a18da7aSGeorge Spelvin /* 19342a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19352a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19362a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19372a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19382a18da7aSGeorge Spelvin * finds the delimiter after the name. 19392a18da7aSGeorge Spelvin */ 19408387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1941bfcfaa77SLinus Torvalds { 19428387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1943bfcfaa77SLinus Torvalds 1944bfcfaa77SLinus Torvalds for (;;) { 1945fcfd2fbfSGeorge Spelvin if (!len) 1946fcfd2fbfSGeorge Spelvin goto done; 1947e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1948bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1949bfcfaa77SLinus Torvalds break; 19502a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1951bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1952bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1953bfcfaa77SLinus Torvalds } 19542a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1955bfcfaa77SLinus Torvalds done: 19562a18da7aSGeorge Spelvin return fold_hash(x, y); 1957bfcfaa77SLinus Torvalds } 1958bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1959bfcfaa77SLinus Torvalds 1960fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19618387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1962fcfd2fbfSGeorge Spelvin { 19638387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19648387ff25SLinus Torvalds unsigned long adata, mask, len; 1965fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1966fcfd2fbfSGeorge Spelvin 19678387ff25SLinus Torvalds len = 0; 19688387ff25SLinus Torvalds goto inside; 19698387ff25SLinus Torvalds 1970fcfd2fbfSGeorge Spelvin do { 19712a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1972fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19738387ff25SLinus Torvalds inside: 1974fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1975fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1976fcfd2fbfSGeorge Spelvin 1977fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1978fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19792a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1980fcfd2fbfSGeorge Spelvin 19812a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1982fcfd2fbfSGeorge Spelvin } 1983fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1984fcfd2fbfSGeorge Spelvin 1985bfcfaa77SLinus Torvalds /* 1986bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1987d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1988bfcfaa77SLinus Torvalds */ 19898387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1990bfcfaa77SLinus Torvalds { 19918387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19928387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 199336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1994bfcfaa77SLinus Torvalds 19958387ff25SLinus Torvalds len = 0; 19968387ff25SLinus Torvalds goto inside; 19978387ff25SLinus Torvalds 1998bfcfaa77SLinus Torvalds do { 19992a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2000bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20018387ff25SLinus Torvalds inside: 2002e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 200336126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 200436126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2005bfcfaa77SLinus Torvalds 200636126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 200736126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 200836126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20092a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 201036126f8fSLinus Torvalds 20112a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2012bfcfaa77SLinus Torvalds } 2013bfcfaa77SLinus Torvalds 20142a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2015bfcfaa77SLinus Torvalds 2016fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20178387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20180145acc2SLinus Torvalds { 20198387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20200145acc2SLinus Torvalds while (len--) 2021fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20220145acc2SLinus Torvalds return end_name_hash(hash); 20230145acc2SLinus Torvalds } 2024ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20250145acc2SLinus Torvalds 2026fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20278387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2028fcfd2fbfSGeorge Spelvin { 20298387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2030fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2031fcfd2fbfSGeorge Spelvin 2032fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2033e0ab7af9SGeorge Spelvin while (c) { 2034fcfd2fbfSGeorge Spelvin len++; 2035fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2036fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2037e0ab7af9SGeorge Spelvin } 2038fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2039fcfd2fbfSGeorge Spelvin } 2040f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2041fcfd2fbfSGeorge Spelvin 20423ddcd056SLinus Torvalds /* 2043200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2044200e9ef7SLinus Torvalds * one character. 2045200e9ef7SLinus Torvalds */ 20468387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2047200e9ef7SLinus Torvalds { 20488387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2049200e9ef7SLinus Torvalds unsigned long len = 0, c; 2050200e9ef7SLinus Torvalds 2051200e9ef7SLinus Torvalds c = (unsigned char)*name; 2052200e9ef7SLinus Torvalds do { 2053200e9ef7SLinus Torvalds len++; 2054200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2055200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2056200e9ef7SLinus Torvalds } while (c && c != '/'); 2057d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2058200e9ef7SLinus Torvalds } 2059200e9ef7SLinus Torvalds 2060bfcfaa77SLinus Torvalds #endif 2061bfcfaa77SLinus Torvalds 2062200e9ef7SLinus Torvalds /* 20631da177e4SLinus Torvalds * Name resolution. 2064ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2065ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20661da177e4SLinus Torvalds * 2067ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2068ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20691da177e4SLinus Torvalds */ 20706de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20711da177e4SLinus Torvalds { 2072d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 20731da177e4SLinus Torvalds int err; 20741da177e4SLinus Torvalds 2075b4c03536SAl Viro nd->last_type = LAST_ROOT; 2076c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 20779b5858e9SAl Viro if (IS_ERR(name)) 20789b5858e9SAl Viro return PTR_ERR(name); 20791da177e4SLinus Torvalds while (*name=='/') 20801da177e4SLinus Torvalds name++; 20811da177e4SLinus Torvalds if (!*name) 20829e18f10aSAl Viro return 0; 20831da177e4SLinus Torvalds 20841da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20851da177e4SLinus Torvalds for(;;) { 208692d27016SAl Viro const char *link; 2087d6bb3e90SLinus Torvalds u64 hash_len; 2088fe479a58SAl Viro int type; 20891da177e4SLinus Torvalds 209052094c8aSAl Viro err = may_lookup(nd); 20911da177e4SLinus Torvalds if (err) 20923595e234SAl Viro return err; 20931da177e4SLinus Torvalds 20948387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20951da177e4SLinus Torvalds 2096fe479a58SAl Viro type = LAST_NORM; 2097d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2098fe479a58SAl Viro case 2: 2099200e9ef7SLinus Torvalds if (name[1] == '.') { 2100fe479a58SAl Viro type = LAST_DOTDOT; 210116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 210216c2cd71SAl Viro } 2103fe479a58SAl Viro break; 2104fe479a58SAl Viro case 1: 2105fe479a58SAl Viro type = LAST_DOT; 2106fe479a58SAl Viro } 21075a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21085a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 210916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21105a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2111a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2112da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21135a202bcdSAl Viro if (err < 0) 21143595e234SAl Viro return err; 2115d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2116d6bb3e90SLinus Torvalds name = this.name; 21175a202bcdSAl Viro } 21185a202bcdSAl Viro } 2119fe479a58SAl Viro 2120d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2121d6bb3e90SLinus Torvalds nd->last.name = name; 21225f4a6a69SAl Viro nd->last_type = type; 21235f4a6a69SAl Viro 2124d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2125d6bb3e90SLinus Torvalds if (!*name) 2126bdf6cbf1SAl Viro goto OK; 2127200e9ef7SLinus Torvalds /* 2128200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2129200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2130200e9ef7SLinus Torvalds */ 2131200e9ef7SLinus Torvalds do { 2132d6bb3e90SLinus Torvalds name++; 2133d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21348620c238SAl Viro if (unlikely(!*name)) { 21358620c238SAl Viro OK: 2136d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2137c108837eSAl Viro if (!depth) { 2138c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 21398620c238SAl Viro return 0; 2140c108837eSAl Viro } 21418620c238SAl Viro /* last component of nested symlink */ 2142d8d4611aSAl Viro name = nd->stack[--depth].name; 21438c4efe22SAl Viro link = walk_component(nd, 0); 21441c4ff1a8SAl Viro } else { 21451c4ff1a8SAl Viro /* not the last component */ 21468c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 21478620c238SAl Viro } 214892d27016SAl Viro if (unlikely(link)) { 214992d27016SAl Viro if (IS_ERR(link)) 215092d27016SAl Viro return PTR_ERR(link); 215192d27016SAl Viro /* a symlink to follow */ 2152d8d4611aSAl Viro nd->stack[depth++].name = name; 215392d27016SAl Viro name = link; 21549e18f10aSAl Viro continue; 215548c8b0c5SAl Viro } 215697242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 215797242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21584675ac39SAl Viro if (unlazy_walk(nd)) 215997242f99SAl Viro return -ECHILD; 216097242f99SAl Viro } 21613595e234SAl Viro return -ENOTDIR; 21625f4a6a69SAl Viro } 2163ce57dfc1SAl Viro } 216497242f99SAl Viro } 21651da177e4SLinus Torvalds 2166edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2167c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 216831e6b01fSNick Piggin { 2169740a1678SAleksa Sarai int error; 2170c8a53ee5SAl Viro const char *s = nd->name->name; 217131e6b01fSNick Piggin 2172c0eb027eSLinus Torvalds if (!*s) 2173c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2174edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2175edc2b1daSAl Viro rcu_read_lock(); 2176c0eb027eSLinus Torvalds 2177c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 217831e6b01fSNick Piggin nd->depth = 0; 2179ab87f9a5SAleksa Sarai 2180ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2181ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2182ab87f9a5SAleksa Sarai smp_rmb(); 2183ab87f9a5SAleksa Sarai 21845b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2185b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2186b18825a7SDavid Howells struct inode *inode = root->d_inode; 218793893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2188368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21895b6ca027SAl Viro nd->path = nd->root; 21905b6ca027SAl Viro nd->inode = inode; 21915b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2192ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 21938f47a016SAl Viro nd->root_seq = nd->seq; 21945b6ca027SAl Viro } else { 21955b6ca027SAl Viro path_get(&nd->path); 21965b6ca027SAl Viro } 2197368ee9baSAl Viro return s; 21985b6ca027SAl Viro } 21995b6ca027SAl Viro 220031e6b01fSNick Piggin nd->root.mnt = NULL; 2201248fb5b9SAl Viro nd->path.mnt = NULL; 2202248fb5b9SAl Viro nd->path.dentry = NULL; 220331e6b01fSNick Piggin 22048db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22058db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2206740a1678SAleksa Sarai error = nd_jump_root(nd); 2207740a1678SAleksa Sarai if (unlikely(error)) 2208740a1678SAleksa Sarai return ERR_PTR(error); 2209ef55d917SAl Viro return s; 22108db52c7eSAleksa Sarai } 22118db52c7eSAleksa Sarai 22128db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22138db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2214e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 221531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2216c28cc364SNick Piggin unsigned seq; 221731e6b01fSNick Piggin 2218c28cc364SNick Piggin do { 2219c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 222031e6b01fSNick Piggin nd->path = fs->pwd; 2221ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2222c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2223c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2224e41f7d4eSAl Viro } else { 2225e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2226ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2227e41f7d4eSAl Viro } 222831e6b01fSNick Piggin } else { 2229582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2230c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 223131e6b01fSNick Piggin struct dentry *dentry; 223231e6b01fSNick Piggin 22332903ff01SAl Viro if (!f.file) 2234368ee9baSAl Viro return ERR_PTR(-EBADF); 223531e6b01fSNick Piggin 22362903ff01SAl Viro dentry = f.file->f_path.dentry; 223731e6b01fSNick Piggin 2238edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22392903ff01SAl Viro fdput(f); 2240368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2241f52e0c11SAl Viro } 22422903ff01SAl Viro 22432903ff01SAl Viro nd->path = f.file->f_path; 2244e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 224534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 224634a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22475590ff0dSUlrich Drepper } else { 22482903ff01SAl Viro path_get(&nd->path); 224934a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22501da177e4SLinus Torvalds } 225134a26b99SAl Viro fdput(f); 2252e41f7d4eSAl Viro } 22538db52c7eSAleksa Sarai 2254adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2255adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2256adb21d2bSAleksa Sarai nd->root = nd->path; 2257adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2258adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2259adb21d2bSAleksa Sarai } else { 2260adb21d2bSAleksa Sarai path_get(&nd->root); 2261adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2262adb21d2bSAleksa Sarai } 2263adb21d2bSAleksa Sarai } 2264adb21d2bSAleksa Sarai return s; 22659b4a9b14SAl Viro } 22669b4a9b14SAl Viro 22671ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 226895fa25d9SAl Viro { 2269bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2270bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2271bd92d7feSAl Viro 2272c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2273bd92d7feSAl Viro } 2274bd92d7feSAl Viro 22754f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22764f757f3cSAl Viro { 2277c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2278db3c9adeSAl Viro dget(nd->path.dentry); 2279b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2280b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 22814f757f3cSAl Viro } 22824f757f3cSAl Viro 22839b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2284c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22859b4a9b14SAl Viro { 2286c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2287bd92d7feSAl Viro int err; 228831e6b01fSNick Piggin 22899b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 22904f757f3cSAl Viro err = handle_lookup_down(nd); 22915f336e72SAl Viro if (unlikely(err < 0)) 22925f336e72SAl Viro s = ERR_PTR(err); 22934f757f3cSAl Viro } 22944f757f3cSAl Viro 22951ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 22961ccac622SAl Viro (s = lookup_last(nd)) != NULL) 22971ccac622SAl Viro ; 22989f1fafeeSAl Viro if (!err) 22999f1fafeeSAl Viro err = complete_walk(nd); 2300bd92d7feSAl Viro 2301deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2302deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2303bd23a539SAl Viro err = -ENOTDIR; 2304161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2305161aff1dSAl Viro err = handle_lookup_down(nd); 2306161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2307161aff1dSAl Viro } 2308625b6d10SAl Viro if (!err) { 2309625b6d10SAl Viro *path = nd->path; 2310625b6d10SAl Viro nd->path.mnt = NULL; 2311625b6d10SAl Viro nd->path.dentry = NULL; 2312625b6d10SAl Viro } 2313deb106c6SAl Viro terminate_walk(nd); 2314bd92d7feSAl Viro return err; 231531e6b01fSNick Piggin } 231631e6b01fSNick Piggin 231731d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23189ad1aaa6SAl Viro struct path *path, struct path *root) 2319873f1eedSJeff Layton { 2320894bc8c4SAl Viro int retval; 23219883d185SAl Viro struct nameidata nd; 2322abc9f5beSAl Viro if (IS_ERR(name)) 2323abc9f5beSAl Viro return PTR_ERR(name); 23249ad1aaa6SAl Viro if (unlikely(root)) { 23259ad1aaa6SAl Viro nd.root = *root; 23269ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23279ad1aaa6SAl Viro } 23289883d185SAl Viro set_nameidata(&nd, dfd, name); 2329c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2330873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2331c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2332873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2333c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2334873f1eedSJeff Layton 2335873f1eedSJeff Layton if (likely(!retval)) 2336161aff1dSAl Viro audit_inode(name, path->dentry, 2337161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23389883d185SAl Viro restore_nameidata(); 2339e4bd1c1aSAl Viro putname(name); 2340873f1eedSJeff Layton return retval; 2341873f1eedSJeff Layton } 2342873f1eedSJeff Layton 23438bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2344c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2345391172c4SAl Viro struct path *parent) 23468bcb77faSAl Viro { 2347c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23489b5858e9SAl Viro int err = link_path_walk(s, nd); 23498bcb77faSAl Viro if (!err) 23508bcb77faSAl Viro err = complete_walk(nd); 2351391172c4SAl Viro if (!err) { 2352391172c4SAl Viro *parent = nd->path; 2353391172c4SAl Viro nd->path.mnt = NULL; 2354391172c4SAl Viro nd->path.dentry = NULL; 2355391172c4SAl Viro } 2356deb106c6SAl Viro terminate_walk(nd); 23578bcb77faSAl Viro return err; 23588bcb77faSAl Viro } 23598bcb77faSAl Viro 23605c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2361391172c4SAl Viro unsigned int flags, struct path *parent, 2362391172c4SAl Viro struct qstr *last, int *type) 23638bcb77faSAl Viro { 23648bcb77faSAl Viro int retval; 23659883d185SAl Viro struct nameidata nd; 23668bcb77faSAl Viro 23675c31b6ceSAl Viro if (IS_ERR(name)) 23685c31b6ceSAl Viro return name; 23699883d185SAl Viro set_nameidata(&nd, dfd, name); 2370c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23718bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2372c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23738bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2374c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2375391172c4SAl Viro if (likely(!retval)) { 2376391172c4SAl Viro *last = nd.last; 2377391172c4SAl Viro *type = nd.last_type; 2378c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 23795c31b6ceSAl Viro } else { 23805c31b6ceSAl Viro putname(name); 23815c31b6ceSAl Viro name = ERR_PTR(retval); 2382391172c4SAl Viro } 23839883d185SAl Viro restore_nameidata(); 23845c31b6ceSAl Viro return name; 23858bcb77faSAl Viro } 23868bcb77faSAl Viro 238779714f72SAl Viro /* does lookup, returns the object with parent locked */ 238879714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23895590ff0dSUlrich Drepper { 23905c31b6ceSAl Viro struct filename *filename; 23915c31b6ceSAl Viro struct dentry *d; 2392391172c4SAl Viro struct qstr last; 2393391172c4SAl Viro int type; 239451689104SPaul Moore 23955c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23965c31b6ceSAl Viro &last, &type); 239751689104SPaul Moore if (IS_ERR(filename)) 239851689104SPaul Moore return ERR_CAST(filename); 23995c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2400391172c4SAl Viro path_put(path); 24015c31b6ceSAl Viro putname(filename); 24025c31b6ceSAl Viro return ERR_PTR(-EINVAL); 240379714f72SAl Viro } 24045955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2405391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 240679714f72SAl Viro if (IS_ERR(d)) { 24075955102cSAl Viro inode_unlock(path->dentry->d_inode); 2408391172c4SAl Viro path_put(path); 240979714f72SAl Viro } 241051689104SPaul Moore putname(filename); 241179714f72SAl Viro return d; 24125590ff0dSUlrich Drepper } 24135590ff0dSUlrich Drepper 2414d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2415d1811465SAl Viro { 2416abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2417abc9f5beSAl Viro flags, path, NULL); 2418d1811465SAl Viro } 24194d359507SAl Viro EXPORT_SYMBOL(kern_path); 2420d1811465SAl Viro 242116f18200SJosef 'Jeff' Sipek /** 242216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 242316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 242416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 242516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 242616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2427e0a01249SAl Viro * @path: pointer to struct path to fill 242816f18200SJosef 'Jeff' Sipek */ 242916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 243016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2431e0a01249SAl Viro struct path *path) 243216f18200SJosef 'Jeff' Sipek { 24339ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24349ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2435abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2436abc9f5beSAl Viro flags , path, &root); 243716f18200SJosef 'Jeff' Sipek } 24384d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 243916f18200SJosef 'Jeff' Sipek 24403c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24413c95f0dcSAl Viro int len, struct qstr *this) 24423c95f0dcSAl Viro { 24433c95f0dcSAl Viro this->name = name; 24443c95f0dcSAl Viro this->len = len; 24453c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24463c95f0dcSAl Viro if (!len) 24473c95f0dcSAl Viro return -EACCES; 24483c95f0dcSAl Viro 24493c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24503c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24513c95f0dcSAl Viro return -EACCES; 24523c95f0dcSAl Viro } 24533c95f0dcSAl Viro 24543c95f0dcSAl Viro while (len--) { 24553c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24563c95f0dcSAl Viro if (c == '/' || c == '\0') 24573c95f0dcSAl Viro return -EACCES; 24583c95f0dcSAl Viro } 24593c95f0dcSAl Viro /* 24603c95f0dcSAl Viro * See if the low-level filesystem might want 24613c95f0dcSAl Viro * to use its own hash.. 24623c95f0dcSAl Viro */ 24633c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24643c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24653c95f0dcSAl Viro if (err < 0) 24663c95f0dcSAl Viro return err; 24673c95f0dcSAl Viro } 24683c95f0dcSAl Viro 24693c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24703c95f0dcSAl Viro } 24713c95f0dcSAl Viro 2472eead1911SChristoph Hellwig /** 24730da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 24740da0b7fdSDavid Howells * @name: pathname component to lookup 24750da0b7fdSDavid Howells * @base: base directory to lookup from 24760da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 24770da0b7fdSDavid Howells * 24780da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 24790da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 24800da0b7fdSDavid Howells * 24810da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 24820da0b7fdSDavid Howells * not be called by generic code. 24830da0b7fdSDavid Howells * 24840da0b7fdSDavid Howells * The caller must hold base->i_mutex. 24850da0b7fdSDavid Howells */ 24860da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 24870da0b7fdSDavid Howells { 24880da0b7fdSDavid Howells struct qstr this; 24890da0b7fdSDavid Howells int err; 24900da0b7fdSDavid Howells 24910da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24920da0b7fdSDavid Howells 24930da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 24940da0b7fdSDavid Howells if (err) 24950da0b7fdSDavid Howells return ERR_PTR(err); 24960da0b7fdSDavid Howells 24970da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 24980da0b7fdSDavid Howells } 24990da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25000da0b7fdSDavid Howells 25010da0b7fdSDavid Howells /** 2502a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2503eead1911SChristoph Hellwig * @name: pathname component to lookup 2504eead1911SChristoph Hellwig * @base: base directory to lookup from 2505eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2506eead1911SChristoph Hellwig * 2507a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25089e7543e9SAl Viro * not be called by generic code. 2509bbddca8eSNeilBrown * 2510bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2511eead1911SChristoph Hellwig */ 2512057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2513057f6c01SJames Morris { 25148613a209SAl Viro struct dentry *dentry; 2515057f6c01SJames Morris struct qstr this; 2516cda309deSMiklos Szeredi int err; 2517057f6c01SJames Morris 25185955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25192f9092e1SDavid Woodhouse 25203c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2521cda309deSMiklos Szeredi if (err) 2522cda309deSMiklos Szeredi return ERR_PTR(err); 2523cda309deSMiklos Szeredi 25248613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25258613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2526057f6c01SJames Morris } 25274d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2528057f6c01SJames Morris 2529bbddca8eSNeilBrown /** 2530bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2531bbddca8eSNeilBrown * @name: pathname component to lookup 2532bbddca8eSNeilBrown * @base: base directory to lookup from 2533bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2534bbddca8eSNeilBrown * 2535bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2536bbddca8eSNeilBrown * not be called by generic code. 2537bbddca8eSNeilBrown * 2538bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2539bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2540bbddca8eSNeilBrown */ 2541bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2542bbddca8eSNeilBrown struct dentry *base, int len) 2543bbddca8eSNeilBrown { 2544bbddca8eSNeilBrown struct qstr this; 2545bbddca8eSNeilBrown int err; 254620d00ee8SLinus Torvalds struct dentry *ret; 2547bbddca8eSNeilBrown 25483c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2549bbddca8eSNeilBrown if (err) 2550bbddca8eSNeilBrown return ERR_PTR(err); 2551bbddca8eSNeilBrown 255220d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 255320d00ee8SLinus Torvalds if (!ret) 255420d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 255520d00ee8SLinus Torvalds return ret; 2556bbddca8eSNeilBrown } 2557bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2558bbddca8eSNeilBrown 25596c2d4798SAl Viro /* 25606c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 25616c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 25626c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 25636c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 25646c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 25656c2d4798SAl Viro * this one avoids such problems. 25666c2d4798SAl Viro */ 25676c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 25686c2d4798SAl Viro struct dentry *base, int len) 25696c2d4798SAl Viro { 25706c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 25712fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 25726c2d4798SAl Viro dput(ret); 25736c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 25746c2d4798SAl Viro } 25756c2d4798SAl Viro return ret; 25766c2d4798SAl Viro } 25776c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 25786c2d4798SAl Viro 2579eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2580eedf265aSEric W. Biederman int path_pts(struct path *path) 2581eedf265aSEric W. Biederman { 2582eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2583eedf265aSEric W. Biederman * the input path. 2584eedf265aSEric W. Biederman */ 2585a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2586a6a7eb76SAl Viro struct dentry *child; 2587eedf265aSEric W. Biederman struct qstr this; 2588eedf265aSEric W. Biederman 2589a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2590a6a7eb76SAl Viro dput(parent); 259163b27720SAl Viro return -ENOENT; 2592a6a7eb76SAl Viro } 259363b27720SAl Viro dput(path->dentry); 259463b27720SAl Viro path->dentry = parent; 2595eedf265aSEric W. Biederman this.name = "pts"; 2596eedf265aSEric W. Biederman this.len = 3; 2597eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2598eedf265aSEric W. Biederman if (!child) 2599eedf265aSEric W. Biederman return -ENOENT; 2600eedf265aSEric W. Biederman 2601eedf265aSEric W. Biederman path->dentry = child; 2602eedf265aSEric W. Biederman dput(parent); 2603eedf265aSEric W. Biederman follow_mount(path); 2604eedf265aSEric W. Biederman return 0; 2605eedf265aSEric W. Biederman } 2606eedf265aSEric W. Biederman #endif 2607eedf265aSEric W. Biederman 26081fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26091fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26101da177e4SLinus Torvalds { 2611abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2612abc9f5beSAl Viro flags, path, NULL); 26131da177e4SLinus Torvalds } 2614b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26151fa1e7f6SAndy Whitcroft 2616cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26171da177e4SLinus Torvalds { 26188e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2619da9592edSDavid Howells 26208e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26211da177e4SLinus Torvalds return 0; 26228e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26231da177e4SLinus Torvalds return 0; 262423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26251da177e4SLinus Torvalds } 2626cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26271da177e4SLinus Torvalds 26281da177e4SLinus Torvalds /* 26291da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26301da177e4SLinus Torvalds * whether the type of victim is right. 26311da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26321da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26331da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26341da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26351da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26361da177e4SLinus Torvalds * a. be owner of dir, or 26371da177e4SLinus Torvalds * b. be owner of victim, or 26381da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26391da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26401da177e4SLinus Torvalds * links pointing to it. 26410bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26420bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26430bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26440bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 26450bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 26461da177e4SLinus Torvalds * nfs_async_unlink(). 26471da177e4SLinus Torvalds */ 2648b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26491da177e4SLinus Torvalds { 265063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26511da177e4SLinus Torvalds int error; 26521da177e4SLinus Torvalds 2653b18825a7SDavid Howells if (d_is_negative(victim)) 26541da177e4SLinus Torvalds return -ENOENT; 2655b18825a7SDavid Howells BUG_ON(!inode); 26561da177e4SLinus Torvalds 26571da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2658593d1ce8SEric W. Biederman 2659593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2660593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2661593d1ce8SEric W. Biederman return -EOVERFLOW; 2662593d1ce8SEric W. Biederman 26634fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 26641da177e4SLinus Torvalds 2665f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 26661da177e4SLinus Torvalds if (error) 26671da177e4SLinus Torvalds return error; 26681da177e4SLinus Torvalds if (IS_APPEND(dir)) 26691da177e4SLinus Torvalds return -EPERM; 2670b18825a7SDavid Howells 2671b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 26720bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 26731da177e4SLinus Torvalds return -EPERM; 26741da177e4SLinus Torvalds if (isdir) { 267544b1d530SMiklos Szeredi if (!d_is_dir(victim)) 26761da177e4SLinus Torvalds return -ENOTDIR; 26771da177e4SLinus Torvalds if (IS_ROOT(victim)) 26781da177e4SLinus Torvalds return -EBUSY; 267944b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 26801da177e4SLinus Torvalds return -EISDIR; 26811da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26821da177e4SLinus Torvalds return -ENOENT; 26831da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 26841da177e4SLinus Torvalds return -EBUSY; 26851da177e4SLinus Torvalds return 0; 26861da177e4SLinus Torvalds } 26871da177e4SLinus Torvalds 26881da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 26891da177e4SLinus Torvalds * dir. 26901da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 26911da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 26921da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2693036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2694036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2695036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 26961da177e4SLinus Torvalds */ 2697a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 26981da177e4SLinus Torvalds { 2699036d5236SEric W. Biederman struct user_namespace *s_user_ns; 270014e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27011da177e4SLinus Torvalds if (child->d_inode) 27021da177e4SLinus Torvalds return -EEXIST; 27031da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27041da177e4SLinus Torvalds return -ENOENT; 2705036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2706036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2707036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2708036d5236SEric W. Biederman return -EOVERFLOW; 2709f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27101da177e4SLinus Torvalds } 27111da177e4SLinus Torvalds 27121da177e4SLinus Torvalds /* 27131da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27141da177e4SLinus Torvalds */ 27151da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27161da177e4SLinus Torvalds { 27171da177e4SLinus Torvalds struct dentry *p; 27181da177e4SLinus Torvalds 27191da177e4SLinus Torvalds if (p1 == p2) { 27205955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27211da177e4SLinus Torvalds return NULL; 27221da177e4SLinus Torvalds } 27231da177e4SLinus Torvalds 2724fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27251da177e4SLinus Torvalds 2726e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2727e2761a11SOGAWA Hirofumi if (p) { 27285955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27295955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27301da177e4SLinus Torvalds return p; 27311da177e4SLinus Torvalds } 27321da177e4SLinus Torvalds 2733e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2734e2761a11SOGAWA Hirofumi if (p) { 27355955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27365955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27371da177e4SLinus Torvalds return p; 27381da177e4SLinus Torvalds } 27391da177e4SLinus Torvalds 27405955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27415955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27421da177e4SLinus Torvalds return NULL; 27431da177e4SLinus Torvalds } 27444d359507SAl Viro EXPORT_SYMBOL(lock_rename); 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 27471da177e4SLinus Torvalds { 27485955102cSAl Viro inode_unlock(p1->d_inode); 27491da177e4SLinus Torvalds if (p1 != p2) { 27505955102cSAl Viro inode_unlock(p2->d_inode); 2751fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 27521da177e4SLinus Torvalds } 27531da177e4SLinus Torvalds } 27544d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 27551da177e4SLinus Torvalds 27564acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2757312b63fbSAl Viro bool want_excl) 27581da177e4SLinus Torvalds { 2759a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27601da177e4SLinus Torvalds if (error) 27611da177e4SLinus Torvalds return error; 27621da177e4SLinus Torvalds 2763acfa4380SAl Viro if (!dir->i_op->create) 27641da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 27651da177e4SLinus Torvalds mode &= S_IALLUGO; 27661da177e4SLinus Torvalds mode |= S_IFREG; 27671da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 27681da177e4SLinus Torvalds if (error) 27691da177e4SLinus Torvalds return error; 2770312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2771a74574aaSStephen Smalley if (!error) 2772f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27731da177e4SLinus Torvalds return error; 27741da177e4SLinus Torvalds } 27754d359507SAl Viro EXPORT_SYMBOL(vfs_create); 27761da177e4SLinus Torvalds 27778e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 27788e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 27798e6c848eSAl Viro void *arg) 27808e6c848eSAl Viro { 27818e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 27828e6c848eSAl Viro int error = may_create(dir, dentry); 27838e6c848eSAl Viro if (error) 27848e6c848eSAl Viro return error; 27858e6c848eSAl Viro 27868e6c848eSAl Viro mode &= S_IALLUGO; 27878e6c848eSAl Viro mode |= S_IFREG; 27888e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 27898e6c848eSAl Viro if (error) 27908e6c848eSAl Viro return error; 27918e6c848eSAl Viro error = f(dentry, mode, arg); 27928e6c848eSAl Viro if (!error) 27938e6c848eSAl Viro fsnotify_create(dir, dentry); 27948e6c848eSAl Viro return error; 27958e6c848eSAl Viro } 27968e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 27978e6c848eSAl Viro 2798a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2799a2982cc9SEric W. Biederman { 2800a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2801a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2802a2982cc9SEric W. Biederman } 2803a2982cc9SEric W. Biederman 2804f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28051da177e4SLinus Torvalds { 28063fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28071da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28081da177e4SLinus Torvalds int error; 28091da177e4SLinus Torvalds 28101da177e4SLinus Torvalds if (!inode) 28111da177e4SLinus Torvalds return -ENOENT; 28121da177e4SLinus Torvalds 2813c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2814c8fe8f30SChristoph Hellwig case S_IFLNK: 28151da177e4SLinus Torvalds return -ELOOP; 2816c8fe8f30SChristoph Hellwig case S_IFDIR: 2817c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28181da177e4SLinus Torvalds return -EISDIR; 2819c8fe8f30SChristoph Hellwig break; 2820c8fe8f30SChristoph Hellwig case S_IFBLK: 2821c8fe8f30SChristoph Hellwig case S_IFCHR: 2822a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28231da177e4SLinus Torvalds return -EACCES; 2824c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2825c8fe8f30SChristoph Hellwig case S_IFIFO: 2826c8fe8f30SChristoph Hellwig case S_IFSOCK: 28271da177e4SLinus Torvalds flag &= ~O_TRUNC; 2828c8fe8f30SChristoph Hellwig break; 28294a3fd211SDave Hansen } 2830b41572e9SDave Hansen 283162fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2832b41572e9SDave Hansen if (error) 2833b41572e9SDave Hansen return error; 28346146f0d5SMimi Zohar 28351da177e4SLinus Torvalds /* 28361da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28371da177e4SLinus Torvalds */ 28381da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28398737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28407715b521SAl Viro return -EPERM; 28411da177e4SLinus Torvalds if (flag & O_TRUNC) 28427715b521SAl Viro return -EPERM; 28431da177e4SLinus Torvalds } 28441da177e4SLinus Torvalds 28451da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28462e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28477715b521SAl Viro return -EPERM; 28481da177e4SLinus Torvalds 2849f3c7691eSJ. Bruce Fields return 0; 28507715b521SAl Viro } 28517715b521SAl Viro 2852e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28537715b521SAl Viro { 2854f0bb5aafSAl Viro const struct path *path = &filp->f_path; 28557715b521SAl Viro struct inode *inode = path->dentry->d_inode; 28567715b521SAl Viro int error = get_write_access(inode); 28571da177e4SLinus Torvalds if (error) 28587715b521SAl Viro return error; 28591da177e4SLinus Torvalds /* 28601da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 28611da177e4SLinus Torvalds */ 2862d7a06983SJeff Layton error = locks_verify_locked(filp); 2863be6d3e56SKentaro Takeda if (!error) 2864ea0d3ab2STetsuo Handa error = security_path_truncate(path); 28651da177e4SLinus Torvalds if (!error) { 28667715b521SAl Viro error = do_truncate(path->dentry, 0, 2867d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2868e1181ee6SJeff Layton filp); 28691da177e4SLinus Torvalds } 28701da177e4SLinus Torvalds put_write_access(inode); 2871acd0c935SMimi Zohar return error; 28721da177e4SLinus Torvalds } 28731da177e4SLinus Torvalds 2874d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2875d57999e1SDave Hansen { 28768a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 28778a5e929dSAl Viro flag--; 2878d57999e1SDave Hansen return flag; 2879d57999e1SDave Hansen } 2880d57999e1SDave Hansen 2881d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2882d18e9008SMiklos Szeredi { 28831328c727SSeth Forshee struct user_namespace *s_user_ns; 2884d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2885d18e9008SMiklos Szeredi if (error) 2886d18e9008SMiklos Szeredi return error; 2887d18e9008SMiklos Szeredi 28881328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 28891328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 28901328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 28911328c727SSeth Forshee return -EOVERFLOW; 28921328c727SSeth Forshee 2893d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2894d18e9008SMiklos Szeredi if (error) 2895d18e9008SMiklos Szeredi return error; 2896d18e9008SMiklos Szeredi 2897d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2898d18e9008SMiklos Szeredi } 2899d18e9008SMiklos Szeredi 29001acf0af9SDavid Howells /* 29011acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29021acf0af9SDavid Howells * dentry. 29031acf0af9SDavid Howells * 29041acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29051acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29061acf0af9SDavid Howells * 290700a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 290800a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 290900a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29101acf0af9SDavid Howells * 29111acf0af9SDavid Howells * Returns an error code otherwise. 29121acf0af9SDavid Howells */ 2913239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2914239eb983SAl Viro struct file *file, 2915015c3bbcSMiklos Szeredi const struct open_flags *op, 29163ec2eef1SAl Viro int open_flag, umode_t mode) 2917d18e9008SMiklos Szeredi { 2918d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2919d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2920d18e9008SMiklos Szeredi int error; 2921d18e9008SMiklos Szeredi 2922384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2923d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2924d18e9008SMiklos Szeredi 2925d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2926d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2927d18e9008SMiklos Szeredi 292830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 292930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29300fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 293144907d79SAl Viro open_to_namei_flags(open_flag), mode); 29326fbd0714SAl Viro d_lookup_done(dentry); 2933384f26e2SAl Viro if (!error) { 293464e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 29356fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 29366fb968cdSAl Viro dput(dentry); 29376fb968cdSAl Viro dentry = dget(file->f_path.dentry); 29386fb968cdSAl Viro } 29397be219b4SAl Viro if (file->f_mode & FMODE_CREATED) 294003da633aSAl Viro fsnotify_create(dir, dentry); 294164e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2942116cc022SMiklos Szeredi error = -EIO; 2943384f26e2SAl Viro } else { 2944d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2945d18e9008SMiklos Szeredi dput(dentry); 2946d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 294710c64ceaSAl Viro } 294873a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 2949d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2950239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 2951a01e718fSAl Viro error = -ENOENT; 2952d18e9008SMiklos Szeredi } 2953d18e9008SMiklos Szeredi } 2954239eb983SAl Viro if (error) { 2955d18e9008SMiklos Szeredi dput(dentry); 2956239eb983SAl Viro dentry = ERR_PTR(error); 2957239eb983SAl Viro } 2958239eb983SAl Viro return dentry; 2959d18e9008SMiklos Szeredi } 2960d18e9008SMiklos Szeredi 296131e6b01fSNick Piggin /* 29621acf0af9SDavid Howells * Look up and maybe create and open the last component. 2963d58ffd35SMiklos Szeredi * 296400a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 2965d58ffd35SMiklos Szeredi * 296600a07c15SAl Viro * Returns 0 on success, that is, if 296700a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 296800a07c15SAl Viro * the file was not completely opened at this time, though lookups and 296900a07c15SAl Viro * creations were performed. 297000a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 297100a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 297200a07c15SAl Viro * hadn't been specified. 29731acf0af9SDavid Howells * 297400a07c15SAl Viro * An error code is returned on failure. 2975d58ffd35SMiklos Szeredi */ 2976da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 2977d58ffd35SMiklos Szeredi const struct open_flags *op, 29783ec2eef1SAl Viro bool got_write) 2979d58ffd35SMiklos Szeredi { 2980d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 298154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 29821643b43fSAl Viro int open_flag = op->open_flag; 2983d58ffd35SMiklos Szeredi struct dentry *dentry; 29841643b43fSAl Viro int error, create_error = 0; 29851643b43fSAl Viro umode_t mode = op->mode; 29866fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 2987d58ffd35SMiklos Szeredi 2988ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 2989da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 2990d58ffd35SMiklos Szeredi 299173a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 29926fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 29936fbd0714SAl Viro for (;;) { 29946fbd0714SAl Viro if (!dentry) { 29956fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 2996d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 2997da5ebf5aSAl Viro return dentry; 29986fbd0714SAl Viro } 29996fbd0714SAl Viro if (d_in_lookup(dentry)) 30006fbd0714SAl Viro break; 3001d58ffd35SMiklos Szeredi 30026fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30036fbd0714SAl Viro if (likely(error > 0)) 30046fbd0714SAl Viro break; 30056fbd0714SAl Viro if (error) 30066fbd0714SAl Viro goto out_dput; 30076fbd0714SAl Viro d_invalidate(dentry); 30086fbd0714SAl Viro dput(dentry); 30096fbd0714SAl Viro dentry = NULL; 30106fbd0714SAl Viro } 30116fbd0714SAl Viro if (dentry->d_inode) { 3012d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3013da5ebf5aSAl Viro return dentry; 30146c51e513SAl Viro } 3015d18e9008SMiklos Szeredi 30161643b43fSAl Viro /* 30171643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30181643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30191643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30201643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30211643b43fSAl Viro * 30221643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30231643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30241643b43fSAl Viro */ 30251643b43fSAl Viro if (open_flag & O_CREAT) { 30261643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30271643b43fSAl Viro mode &= ~current_umask(); 30281643b43fSAl Viro if (unlikely(!got_write)) { 30291643b43fSAl Viro create_error = -EROFS; 30301643b43fSAl Viro open_flag &= ~O_CREAT; 30311643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30321643b43fSAl Viro goto no_open; 30331643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30341643b43fSAl Viro } else { 30351643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30361643b43fSAl Viro if (create_error) { 30371643b43fSAl Viro open_flag &= ~O_CREAT; 30381643b43fSAl Viro if (open_flag & O_EXCL) 30391643b43fSAl Viro goto no_open; 30401643b43fSAl Viro } 30411643b43fSAl Viro } 30421643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30431643b43fSAl Viro unlikely(!got_write)) { 30441643b43fSAl Viro /* 30451643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30461643b43fSAl Viro * back to lookup + open 30471643b43fSAl Viro */ 30481643b43fSAl Viro goto no_open; 3049d18e9008SMiklos Szeredi } 3050d18e9008SMiklos Szeredi 30511643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3052239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3053da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3054da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3055da5ebf5aSAl Viro return dentry; 3056239eb983SAl Viro } 305754ef4872SMiklos Szeredi 30581643b43fSAl Viro no_open: 30596fbd0714SAl Viro if (d_in_lookup(dentry)) { 306012fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 306112fa5e24SAl Viro nd->flags); 30626fbd0714SAl Viro d_lookup_done(dentry); 306312fa5e24SAl Viro if (unlikely(res)) { 306412fa5e24SAl Viro if (IS_ERR(res)) { 306512fa5e24SAl Viro error = PTR_ERR(res); 306612fa5e24SAl Viro goto out_dput; 306712fa5e24SAl Viro } 306812fa5e24SAl Viro dput(dentry); 306912fa5e24SAl Viro dentry = res; 307012fa5e24SAl Viro } 307154ef4872SMiklos Szeredi } 307254ef4872SMiklos Szeredi 3073d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 30741643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 307573a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3076ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3077ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3078ce8644fcSAl Viro error = -EACCES; 3079d58ffd35SMiklos Szeredi goto out_dput; 308064894cf8SAl Viro } 3081ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 30821643b43fSAl Viro open_flag & O_EXCL); 3083d58ffd35SMiklos Szeredi if (error) 3084d58ffd35SMiklos Szeredi goto out_dput; 3085ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3086d58ffd35SMiklos Szeredi } 30871643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 30881643b43fSAl Viro error = create_error; 3089d58ffd35SMiklos Szeredi goto out_dput; 3090d58ffd35SMiklos Szeredi } 3091da5ebf5aSAl Viro return dentry; 3092d58ffd35SMiklos Szeredi 3093d58ffd35SMiklos Szeredi out_dput: 3094d58ffd35SMiklos Szeredi dput(dentry); 3095da5ebf5aSAl Viro return ERR_PTR(error); 3096d58ffd35SMiklos Szeredi } 3097d58ffd35SMiklos Szeredi 3098c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 30993ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3100fb1cc555SAl Viro { 3101a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3102ca344a89SAl Viro int open_flag = op->open_flag; 310364894cf8SAl Viro bool got_write = false; 3104254cf582SAl Viro unsigned seq; 3105a1eb3315SMiklos Szeredi struct inode *inode; 3106da5ebf5aSAl Viro struct dentry *dentry; 3107b0417d2cSAl Viro const char *res; 310816c2cd71SAl Viro int error; 3109fb1cc555SAl Viro 3110c3e380b0SAl Viro nd->flags |= op->intent; 3111c3e380b0SAl Viro 3112bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 311356676ec3SAl Viro if (nd->depth) 311456676ec3SAl Viro put_link(nd); 31157521f22bSAl Viro res = handle_dots(nd, nd->last_type); 31167521f22bSAl Viro if (likely(!res)) 31177521f22bSAl Viro res = ERR_PTR(complete_walk(nd)); 31187521f22bSAl Viro return res; 31191f36f774SAl Viro } 3120a2c36b45SAl Viro 3121ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3122fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3123fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3124fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 312520e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 312620e34357SAl Viro if (IS_ERR(dentry)) 31271ccac622SAl Viro return ERR_CAST(dentry); 312820e34357SAl Viro if (likely(dentry)) 312971574865SMiklos Szeredi goto finish_lookup; 313071574865SMiklos Szeredi 31316583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3132b6183df7SMiklos Szeredi } else { 3133fe2d35ffSAl Viro /* create side of things */ 3134a3fbbde7SAl Viro /* 3135b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3136b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3137b6183df7SMiklos Szeredi * about to look up 3138a3fbbde7SAl Viro */ 31399f1fafeeSAl Viro error = complete_walk(nd); 3140c981a482SAl Viro if (unlikely(error)) 31411ccac622SAl Viro return ERR_PTR(error); 3142fe2d35ffSAl Viro 3143c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 31441f36f774SAl Viro /* trailing slashes? */ 3145deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 31461ccac622SAl Viro return ERR_PTR(-EISDIR); 3147b6183df7SMiklos Szeredi } 31481f36f774SAl Viro 31499cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 315064894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 315164894cf8SAl Viro if (!error) 315264894cf8SAl Viro got_write = true; 315364894cf8SAl Viro /* 315464894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 315564894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 315664894cf8SAl Viro * dropping this one anyway. 315764894cf8SAl Viro */ 315864894cf8SAl Viro } 31599cf843e3SAl Viro if (open_flag & O_CREAT) 31605955102cSAl Viro inode_lock(dir->d_inode); 31619cf843e3SAl Viro else 31629cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3163da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 31649cf843e3SAl Viro if (open_flag & O_CREAT) 31655955102cSAl Viro inode_unlock(dir->d_inode); 31669cf843e3SAl Viro else 31679cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3168fb1cc555SAl Viro 3169c981a482SAl Viro if (got_write) 317059e96e65SAl Viro mnt_drop_write(nd->path.mnt); 31716c0d46c4SAl Viro 317259e96e65SAl Viro if (IS_ERR(dentry)) 317359e96e65SAl Viro return ERR_CAST(dentry); 317459e96e65SAl Viro 3175973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3176e73cabffSAl Viro dput(nd->path.dentry); 3177e73cabffSAl Viro nd->path.dentry = dentry; 3178c981a482SAl Viro return NULL; 3179fb1cc555SAl Viro } 3180fb1cc555SAl Viro 318120e34357SAl Viro finish_lookup: 318256676ec3SAl Viro if (nd->depth) 318356676ec3SAl Viro put_link(nd); 31848c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3185b0417d2cSAl Viro if (unlikely(res)) { 31861ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3187b0417d2cSAl Viro return res; 31881ccac622SAl Viro } 318931d1726dSAl Viro 319031d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 319131d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 31921ccac622SAl Viro return ERR_PTR(-EEXIST); 319331d1726dSAl Viro } 3194c981a482SAl Viro 31958f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3196c981a482SAl Viro return ERR_PTR(complete_walk(nd)); 3197c981a482SAl Viro } 3198c981a482SAl Viro 3199c981a482SAl Viro /* 3200c981a482SAl Viro * Handle the last step of open() 3201c981a482SAl Viro */ 3202c981a482SAl Viro static const char *do_last(struct nameidata *nd, 3203c981a482SAl Viro struct file *file, const struct open_flags *op) 3204c981a482SAl Viro { 3205c981a482SAl Viro kuid_t dir_uid = nd->inode->i_uid; 3206c981a482SAl Viro umode_t dir_mode = nd->inode->i_mode; 3207c981a482SAl Viro int open_flag = op->open_flag; 3208c981a482SAl Viro bool do_truncate; 3209c981a482SAl Viro int acc_mode; 3210c981a482SAl Viro const char *link; 3211c981a482SAl Viro int error; 3212c981a482SAl Viro 3213c981a482SAl Viro link = open_last_lookups(nd, file, op); 3214c981a482SAl Viro if (unlikely(link)) 3215c981a482SAl Viro return link; 3216c981a482SAl Viro 3217973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 321876ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 321930aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 322030aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 322159e96e65SAl Viro return ERR_PTR(-EISDIR); 3222d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 322330aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 322430aba665SSalvatore Mesoraca if (unlikely(error)) 322559e96e65SAl Viro return ERR_PTR(error); 322630aba665SSalvatore Mesoraca } 322744b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 322859e96e65SAl Viro return ERR_PTR(-ENOTDIR); 32296c0d46c4SAl Viro 32308795e7d4SAl Viro do_truncate = false; 32318795e7d4SAl Viro acc_mode = op->acc_mode; 32325a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32335a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32345a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32355a2d3eddSAl Viro acc_mode = 0; 32368795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32370f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32380f9d1a10SAl Viro if (error) 323959e96e65SAl Viro return ERR_PTR(error); 32408795e7d4SAl Viro do_truncate = true; 32410f9d1a10SAl Viro } 3242bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 32438795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3244ae2bb293SAl Viro error = vfs_open(&nd->path, file); 32458795e7d4SAl Viro if (!error) 32466035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 32478795e7d4SAl Viro if (!error && do_truncate) 32482675a4ebSAl Viro error = handle_truncate(file); 3249c80567c8SAl Viro if (unlikely(error > 0)) { 3250c80567c8SAl Viro WARN_ON(1); 3251c80567c8SAl Viro error = -EINVAL; 3252c80567c8SAl Viro } 32538795e7d4SAl Viro if (do_truncate) 32540f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 32551ccac622SAl Viro return ERR_PTR(error); 3256fb1cc555SAl Viro } 3257fb1cc555SAl Viro 3258af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3259af7bd4dcSAmir Goldstein { 3260af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3261af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3262af7bd4dcSAmir Goldstein struct inode *inode; 3263af7bd4dcSAmir Goldstein int error; 3264af7bd4dcSAmir Goldstein 3265af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3266af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3267af7bd4dcSAmir Goldstein if (error) 3268af7bd4dcSAmir Goldstein goto out_err; 3269af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3270af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3271af7bd4dcSAmir Goldstein goto out_err; 3272af7bd4dcSAmir Goldstein error = -ENOMEM; 3273cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3274af7bd4dcSAmir Goldstein if (unlikely(!child)) 3275af7bd4dcSAmir Goldstein goto out_err; 3276af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3277af7bd4dcSAmir Goldstein if (error) 3278af7bd4dcSAmir Goldstein goto out_err; 3279af7bd4dcSAmir Goldstein error = -ENOENT; 3280af7bd4dcSAmir Goldstein inode = child->d_inode; 3281af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3282af7bd4dcSAmir Goldstein goto out_err; 3283af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3284af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3285af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3286af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3287af7bd4dcSAmir Goldstein } 3288fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3289af7bd4dcSAmir Goldstein return child; 3290af7bd4dcSAmir Goldstein 3291af7bd4dcSAmir Goldstein out_err: 3292af7bd4dcSAmir Goldstein dput(child); 3293af7bd4dcSAmir Goldstein return ERR_PTR(error); 3294af7bd4dcSAmir Goldstein } 3295af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3296af7bd4dcSAmir Goldstein 3297c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 329860545d0dSAl Viro const struct open_flags *op, 32993ec2eef1SAl Viro struct file *file) 330060545d0dSAl Viro { 3301625b6d10SAl Viro struct dentry *child; 3302625b6d10SAl Viro struct path path; 3303c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 330460545d0dSAl Viro if (unlikely(error)) 330560545d0dSAl Viro return error; 3306625b6d10SAl Viro error = mnt_want_write(path.mnt); 330760545d0dSAl Viro if (unlikely(error)) 330860545d0dSAl Viro goto out; 3309af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3310af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3311684e73beSHirofumi Nakagawa if (IS_ERR(child)) 331260545d0dSAl Viro goto out2; 3313625b6d10SAl Viro dput(path.dentry); 3314625b6d10SAl Viro path.dentry = child; 3315c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 331669a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 331762fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 331860545d0dSAl Viro if (error) 331960545d0dSAl Viro goto out2; 3320625b6d10SAl Viro file->f_path.mnt = path.mnt; 3321be12af3eSAl Viro error = finish_open(file, child, NULL); 332260545d0dSAl Viro out2: 3323625b6d10SAl Viro mnt_drop_write(path.mnt); 332460545d0dSAl Viro out: 3325625b6d10SAl Viro path_put(&path); 332660545d0dSAl Viro return error; 332760545d0dSAl Viro } 332860545d0dSAl Viro 33296ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33306ac08709SAl Viro { 33316ac08709SAl Viro struct path path; 33326ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33336ac08709SAl Viro if (!error) { 33346ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3335ae2bb293SAl Viro error = vfs_open(&path, file); 33366ac08709SAl Viro path_put(&path); 33376ac08709SAl Viro } 33386ac08709SAl Viro return error; 33396ac08709SAl Viro } 33406ac08709SAl Viro 3341c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3342c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33431da177e4SLinus Torvalds { 334430d90494SAl Viro struct file *file; 334513aab428SAl Viro int error; 334631e6b01fSNick Piggin 3347ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 33481afc99beSAl Viro if (IS_ERR(file)) 33491afc99beSAl Viro return file; 335031e6b01fSNick Piggin 3351bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 33523ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 33535f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 33546ac08709SAl Viro error = do_o_path(nd, flags, file); 33555f336e72SAl Viro } else { 33565f336e72SAl Viro const char *s = path_init(nd, flags); 33573bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33581ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 33591ccac622SAl Viro ; 3360deb106c6SAl Viro terminate_walk(nd); 33615f336e72SAl Viro } 33627c1c01ecSAl Viro if (likely(!error)) { 3363aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 33647c1c01ecSAl Viro return file; 33657c1c01ecSAl Viro WARN_ON(1); 33667c1c01ecSAl Viro error = -EINVAL; 3367015c3bbcSMiklos Szeredi } 33687c1c01ecSAl Viro fput(file); 33692675a4ebSAl Viro if (error == -EOPENSTALE) { 33702675a4ebSAl Viro if (flags & LOOKUP_RCU) 33712675a4ebSAl Viro error = -ECHILD; 33722675a4ebSAl Viro else 33732675a4ebSAl Viro error = -ESTALE; 33742675a4ebSAl Viro } 33757c1c01ecSAl Viro return ERR_PTR(error); 3376de459215SKirill Korotaev } 33771da177e4SLinus Torvalds 3378669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3379f9652e10SAl Viro const struct open_flags *op) 338013aab428SAl Viro { 33819883d185SAl Viro struct nameidata nd; 3382f9652e10SAl Viro int flags = op->lookup_flags; 338313aab428SAl Viro struct file *filp; 338413aab428SAl Viro 33859883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3386c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 338713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3388c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 338913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3390c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 33919883d185SAl Viro restore_nameidata(); 339213aab428SAl Viro return filp; 339313aab428SAl Viro } 339413aab428SAl Viro 339573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3396f9652e10SAl Viro const char *name, const struct open_flags *op) 339773d049a4SAl Viro { 33989883d185SAl Viro struct nameidata nd; 339973d049a4SAl Viro struct file *file; 340051689104SPaul Moore struct filename *filename; 3401f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 340273d049a4SAl Viro 340373d049a4SAl Viro nd.root.mnt = mnt; 340473d049a4SAl Viro nd.root.dentry = dentry; 340573d049a4SAl Viro 3406b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 340773d049a4SAl Viro return ERR_PTR(-ELOOP); 340873d049a4SAl Viro 340951689104SPaul Moore filename = getname_kernel(name); 3410a1c83681SViresh Kumar if (IS_ERR(filename)) 341151689104SPaul Moore return ERR_CAST(filename); 341251689104SPaul Moore 34139883d185SAl Viro set_nameidata(&nd, -1, filename); 3414c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 341573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3416c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 341773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3418c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34199883d185SAl Viro restore_nameidata(); 342051689104SPaul Moore putname(filename); 342173d049a4SAl Viro return file; 342273d049a4SAl Viro } 342373d049a4SAl Viro 3424fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34251ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34261da177e4SLinus Torvalds { 3427c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3428391172c4SAl Viro struct qstr last; 3429391172c4SAl Viro int type; 3430c30dabfeSJan Kara int err2; 34311ac12b4bSJeff Layton int error; 34321ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34331ac12b4bSJeff Layton 34341ac12b4bSJeff Layton /* 34351ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34361ac12b4bSJeff Layton * other flags passed in are ignored! 34371ac12b4bSJeff Layton */ 34381ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34391ac12b4bSJeff Layton 34405c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34415c31b6ceSAl Viro if (IS_ERR(name)) 34425c31b6ceSAl Viro return ERR_CAST(name); 34431da177e4SLinus Torvalds 3444c663e5d8SChristoph Hellwig /* 3445c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3446c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3447c663e5d8SChristoph Hellwig */ 34485c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3449ed75e95dSAl Viro goto out; 3450c663e5d8SChristoph Hellwig 3451c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3452391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3453c663e5d8SChristoph Hellwig /* 3454c663e5d8SChristoph Hellwig * Do the final lookup. 3455c663e5d8SChristoph Hellwig */ 3456391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 34575955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3458391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34591da177e4SLinus Torvalds if (IS_ERR(dentry)) 3460a8104a9fSAl Viro goto unlock; 3461c663e5d8SChristoph Hellwig 3462a8104a9fSAl Viro error = -EEXIST; 3463b18825a7SDavid Howells if (d_is_positive(dentry)) 3464a8104a9fSAl Viro goto fail; 3465b18825a7SDavid Howells 3466c663e5d8SChristoph Hellwig /* 3467c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3468c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3469c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3470c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3471c663e5d8SChristoph Hellwig */ 3472391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3473a8104a9fSAl Viro error = -ENOENT; 3474ed75e95dSAl Viro goto fail; 3475e9baf6e5SAl Viro } 3476c30dabfeSJan Kara if (unlikely(err2)) { 3477c30dabfeSJan Kara error = err2; 3478a8104a9fSAl Viro goto fail; 3479c30dabfeSJan Kara } 3480181c37b6SAl Viro putname(name); 3481e9baf6e5SAl Viro return dentry; 34821da177e4SLinus Torvalds fail: 3483a8104a9fSAl Viro dput(dentry); 3484a8104a9fSAl Viro dentry = ERR_PTR(error); 3485a8104a9fSAl Viro unlock: 34865955102cSAl Viro inode_unlock(path->dentry->d_inode); 3487c30dabfeSJan Kara if (!err2) 3488391172c4SAl Viro mnt_drop_write(path->mnt); 3489ed75e95dSAl Viro out: 3490391172c4SAl Viro path_put(path); 3491181c37b6SAl Viro putname(name); 3492ed75e95dSAl Viro return dentry; 3493dae6ad8fSAl Viro } 3494fa14a0b8SAl Viro 3495fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3496fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3497fa14a0b8SAl Viro { 3498181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3499181c37b6SAl Viro path, lookup_flags); 3500fa14a0b8SAl Viro } 3501dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3502dae6ad8fSAl Viro 3503921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3504921a1650SAl Viro { 3505921a1650SAl Viro dput(dentry); 35065955102cSAl Viro inode_unlock(path->dentry->d_inode); 3507a8104a9fSAl Viro mnt_drop_write(path->mnt); 3508921a1650SAl Viro path_put(path); 3509921a1650SAl Viro } 3510921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3511921a1650SAl Viro 3512520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35131ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3514dae6ad8fSAl Viro { 3515181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3516dae6ad8fSAl Viro } 3517dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3518dae6ad8fSAl Viro 35191a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35201da177e4SLinus Torvalds { 3521a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35221da177e4SLinus Torvalds 35231da177e4SLinus Torvalds if (error) 35241da177e4SLinus Torvalds return error; 35251da177e4SLinus Torvalds 352694f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35271da177e4SLinus Torvalds return -EPERM; 35281da177e4SLinus Torvalds 3529acfa4380SAl Viro if (!dir->i_op->mknod) 35301da177e4SLinus Torvalds return -EPERM; 35311da177e4SLinus Torvalds 353208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 353308ce5f16SSerge E. Hallyn if (error) 353408ce5f16SSerge E. Hallyn return error; 353508ce5f16SSerge E. Hallyn 35361da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35371da177e4SLinus Torvalds if (error) 35381da177e4SLinus Torvalds return error; 35391da177e4SLinus Torvalds 35401da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3541a74574aaSStephen Smalley if (!error) 3542f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35431da177e4SLinus Torvalds return error; 35441da177e4SLinus Torvalds } 35454d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35461da177e4SLinus Torvalds 3547f69aac00SAl Viro static int may_mknod(umode_t mode) 3548463c3197SDave Hansen { 3549463c3197SDave Hansen switch (mode & S_IFMT) { 3550463c3197SDave Hansen case S_IFREG: 3551463c3197SDave Hansen case S_IFCHR: 3552463c3197SDave Hansen case S_IFBLK: 3553463c3197SDave Hansen case S_IFIFO: 3554463c3197SDave Hansen case S_IFSOCK: 3555463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3556463c3197SDave Hansen return 0; 3557463c3197SDave Hansen case S_IFDIR: 3558463c3197SDave Hansen return -EPERM; 3559463c3197SDave Hansen default: 3560463c3197SDave Hansen return -EINVAL; 3561463c3197SDave Hansen } 3562463c3197SDave Hansen } 3563463c3197SDave Hansen 356487c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 356587c4e192SDominik Brodowski unsigned int dev) 35661da177e4SLinus Torvalds { 35671da177e4SLinus Torvalds struct dentry *dentry; 3568dae6ad8fSAl Viro struct path path; 3569dae6ad8fSAl Viro int error; 3570972567f1SJeff Layton unsigned int lookup_flags = 0; 35711da177e4SLinus Torvalds 35728e4bfca1SAl Viro error = may_mknod(mode); 35738e4bfca1SAl Viro if (error) 35748e4bfca1SAl Viro return error; 3575972567f1SJeff Layton retry: 3576972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3577dae6ad8fSAl Viro if (IS_ERR(dentry)) 3578dae6ad8fSAl Viro return PTR_ERR(dentry); 35792ad94ae6SAl Viro 3580dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3581ce3b0f8dSAl Viro mode &= ~current_umask(); 3582dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3583be6d3e56SKentaro Takeda if (error) 3584a8104a9fSAl Viro goto out; 35851da177e4SLinus Torvalds switch (mode & S_IFMT) { 35861da177e4SLinus Torvalds case 0: case S_IFREG: 3587312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 358805d1a717SMimi Zohar if (!error) 358905d1a717SMimi Zohar ima_post_path_mknod(dentry); 35901da177e4SLinus Torvalds break; 35911da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3592dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35931da177e4SLinus Torvalds new_decode_dev(dev)); 35941da177e4SLinus Torvalds break; 35951da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3596dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35971da177e4SLinus Torvalds break; 35981da177e4SLinus Torvalds } 3599a8104a9fSAl Viro out: 3600921a1650SAl Viro done_path_create(&path, dentry); 3601972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3602972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3603972567f1SJeff Layton goto retry; 3604972567f1SJeff Layton } 36051da177e4SLinus Torvalds return error; 36061da177e4SLinus Torvalds } 36071da177e4SLinus Torvalds 360887c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 360987c4e192SDominik Brodowski unsigned int, dev) 361087c4e192SDominik Brodowski { 361187c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 361287c4e192SDominik Brodowski } 361387c4e192SDominik Brodowski 36148208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36155590ff0dSUlrich Drepper { 361687c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36175590ff0dSUlrich Drepper } 36185590ff0dSUlrich Drepper 361918bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36201da177e4SLinus Torvalds { 3621a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36228de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36231da177e4SLinus Torvalds 36241da177e4SLinus Torvalds if (error) 36251da177e4SLinus Torvalds return error; 36261da177e4SLinus Torvalds 3627acfa4380SAl Viro if (!dir->i_op->mkdir) 36281da177e4SLinus Torvalds return -EPERM; 36291da177e4SLinus Torvalds 36301da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36311da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36321da177e4SLinus Torvalds if (error) 36331da177e4SLinus Torvalds return error; 36341da177e4SLinus Torvalds 36358de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36368de52778SAl Viro return -EMLINK; 36378de52778SAl Viro 36381da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3639a74574aaSStephen Smalley if (!error) 3640f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36411da177e4SLinus Torvalds return error; 36421da177e4SLinus Torvalds } 36434d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36441da177e4SLinus Torvalds 36450101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 36461da177e4SLinus Torvalds { 36476902d925SDave Hansen struct dentry *dentry; 3648dae6ad8fSAl Viro struct path path; 3649dae6ad8fSAl Viro int error; 3650b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36511da177e4SLinus Torvalds 3652b76d8b82SJeff Layton retry: 3653b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36546902d925SDave Hansen if (IS_ERR(dentry)) 3655dae6ad8fSAl Viro return PTR_ERR(dentry); 36566902d925SDave Hansen 3657dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3658ce3b0f8dSAl Viro mode &= ~current_umask(); 3659dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3660a8104a9fSAl Viro if (!error) 3661dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3662921a1650SAl Viro done_path_create(&path, dentry); 3663b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3664b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3665b76d8b82SJeff Layton goto retry; 3666b76d8b82SJeff Layton } 36671da177e4SLinus Torvalds return error; 36681da177e4SLinus Torvalds } 36691da177e4SLinus Torvalds 36700101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36710101db7aSDominik Brodowski { 36720101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 36730101db7aSDominik Brodowski } 36740101db7aSDominik Brodowski 3675a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36765590ff0dSUlrich Drepper { 36770101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 36785590ff0dSUlrich Drepper } 36795590ff0dSUlrich Drepper 36801da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36811da177e4SLinus Torvalds { 36821da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36831da177e4SLinus Torvalds 36841da177e4SLinus Torvalds if (error) 36851da177e4SLinus Torvalds return error; 36861da177e4SLinus Torvalds 3687acfa4380SAl Viro if (!dir->i_op->rmdir) 36881da177e4SLinus Torvalds return -EPERM; 36891da177e4SLinus Torvalds 36901d2ef590SAl Viro dget(dentry); 36915955102cSAl Viro inode_lock(dentry->d_inode); 3692912dbc15SSage Weil 36931da177e4SLinus Torvalds error = -EBUSY; 36947af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3695912dbc15SSage Weil goto out; 3696912dbc15SSage Weil 36971da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3698912dbc15SSage Weil if (error) 3699912dbc15SSage Weil goto out; 3700912dbc15SSage Weil 37011da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3702912dbc15SSage Weil if (error) 3703912dbc15SSage Weil goto out; 3704912dbc15SSage Weil 37058767712fSAl Viro shrink_dcache_parent(dentry); 37061da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3707d83c49f3SAl Viro dont_mount(dentry); 37088ed936b5SEric W. Biederman detach_mounts(dentry); 3709116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37101da177e4SLinus Torvalds 3711912dbc15SSage Weil out: 37125955102cSAl Viro inode_unlock(dentry->d_inode); 37131d2ef590SAl Viro dput(dentry); 3714912dbc15SSage Weil if (!error) 3715912dbc15SSage Weil d_delete(dentry); 37161da177e4SLinus Torvalds return error; 37171da177e4SLinus Torvalds } 37184d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37191da177e4SLinus Torvalds 3720f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37211da177e4SLinus Torvalds { 37221da177e4SLinus Torvalds int error = 0; 372391a27b2aSJeff Layton struct filename *name; 37241da177e4SLinus Torvalds struct dentry *dentry; 3725f5beed75SAl Viro struct path path; 3726f5beed75SAl Viro struct qstr last; 3727f5beed75SAl Viro int type; 3728c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3729c6ee9206SJeff Layton retry: 3730c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3731c1d4dd27SAl Viro &path, &last, &type); 373291a27b2aSJeff Layton if (IS_ERR(name)) 373391a27b2aSJeff Layton return PTR_ERR(name); 37341da177e4SLinus Torvalds 3735f5beed75SAl Viro switch (type) { 37361da177e4SLinus Torvalds case LAST_DOTDOT: 37371da177e4SLinus Torvalds error = -ENOTEMPTY; 37381da177e4SLinus Torvalds goto exit1; 37391da177e4SLinus Torvalds case LAST_DOT: 37401da177e4SLinus Torvalds error = -EINVAL; 37411da177e4SLinus Torvalds goto exit1; 37421da177e4SLinus Torvalds case LAST_ROOT: 37431da177e4SLinus Torvalds error = -EBUSY; 37441da177e4SLinus Torvalds goto exit1; 37451da177e4SLinus Torvalds } 37460612d9fbSOGAWA Hirofumi 3747f5beed75SAl Viro error = mnt_want_write(path.mnt); 3748c30dabfeSJan Kara if (error) 3749c30dabfeSJan Kara goto exit1; 37500612d9fbSOGAWA Hirofumi 37515955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3752f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37531da177e4SLinus Torvalds error = PTR_ERR(dentry); 37546902d925SDave Hansen if (IS_ERR(dentry)) 37556902d925SDave Hansen goto exit2; 3756e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3757e6bc45d6STheodore Ts'o error = -ENOENT; 3758e6bc45d6STheodore Ts'o goto exit3; 3759e6bc45d6STheodore Ts'o } 3760f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3761be6d3e56SKentaro Takeda if (error) 3762c30dabfeSJan Kara goto exit3; 3763f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37640622753bSDave Hansen exit3: 37651da177e4SLinus Torvalds dput(dentry); 37666902d925SDave Hansen exit2: 37675955102cSAl Viro inode_unlock(path.dentry->d_inode); 3768f5beed75SAl Viro mnt_drop_write(path.mnt); 37691da177e4SLinus Torvalds exit1: 3770f5beed75SAl Viro path_put(&path); 37711da177e4SLinus Torvalds putname(name); 3772c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3773c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3774c6ee9206SJeff Layton goto retry; 3775c6ee9206SJeff Layton } 37761da177e4SLinus Torvalds return error; 37771da177e4SLinus Torvalds } 37781da177e4SLinus Torvalds 37793cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37805590ff0dSUlrich Drepper { 37815590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37825590ff0dSUlrich Drepper } 37835590ff0dSUlrich Drepper 3784b21996e3SJ. Bruce Fields /** 3785b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3786b21996e3SJ. Bruce Fields * @dir: parent directory 3787b21996e3SJ. Bruce Fields * @dentry: victim 3788b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3789b21996e3SJ. Bruce Fields * 3790b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3791b21996e3SJ. Bruce Fields * 3792b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3793b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3794b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3795b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3796b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3797b21996e3SJ. Bruce Fields * 3798b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3799b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3800b21996e3SJ. Bruce Fields * to be NFS exported. 3801b21996e3SJ. Bruce Fields */ 3802b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38031da177e4SLinus Torvalds { 38049accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38051da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38061da177e4SLinus Torvalds 38071da177e4SLinus Torvalds if (error) 38081da177e4SLinus Torvalds return error; 38091da177e4SLinus Torvalds 3810acfa4380SAl Viro if (!dir->i_op->unlink) 38111da177e4SLinus Torvalds return -EPERM; 38121da177e4SLinus Torvalds 38135955102cSAl Viro inode_lock(target); 38148ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38151da177e4SLinus Torvalds error = -EBUSY; 38161da177e4SLinus Torvalds else { 38171da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3818bec1052eSAl Viro if (!error) { 38195a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38205a14696cSJ. Bruce Fields if (error) 3821b21996e3SJ. Bruce Fields goto out; 38221da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38238ed936b5SEric W. Biederman if (!error) { 3824d83c49f3SAl Viro dont_mount(dentry); 38258ed936b5SEric W. Biederman detach_mounts(dentry); 3826116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38278ed936b5SEric W. Biederman } 3828bec1052eSAl Viro } 38291da177e4SLinus Torvalds } 3830b21996e3SJ. Bruce Fields out: 38315955102cSAl Viro inode_unlock(target); 38321da177e4SLinus Torvalds 38331da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38341da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38359accbb97SJ. Bruce Fields fsnotify_link_count(target); 38361da177e4SLinus Torvalds d_delete(dentry); 38371da177e4SLinus Torvalds } 38380eeca283SRobert Love 38391da177e4SLinus Torvalds return error; 38401da177e4SLinus Torvalds } 38414d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38421da177e4SLinus Torvalds 38431da177e4SLinus Torvalds /* 38441da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38451b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38461da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38471da177e4SLinus Torvalds * while waiting on the I/O. 38481da177e4SLinus Torvalds */ 3849da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 38501da177e4SLinus Torvalds { 38512ad94ae6SAl Viro int error; 38521da177e4SLinus Torvalds struct dentry *dentry; 3853f5beed75SAl Viro struct path path; 3854f5beed75SAl Viro struct qstr last; 3855f5beed75SAl Viro int type; 38561da177e4SLinus Torvalds struct inode *inode = NULL; 3857b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38585d18f813SJeff Layton unsigned int lookup_flags = 0; 38595d18f813SJeff Layton retry: 3860da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 386191a27b2aSJeff Layton if (IS_ERR(name)) 386291a27b2aSJeff Layton return PTR_ERR(name); 38632ad94ae6SAl Viro 38641da177e4SLinus Torvalds error = -EISDIR; 3865f5beed75SAl Viro if (type != LAST_NORM) 38661da177e4SLinus Torvalds goto exit1; 38670612d9fbSOGAWA Hirofumi 3868f5beed75SAl Viro error = mnt_want_write(path.mnt); 3869c30dabfeSJan Kara if (error) 3870c30dabfeSJan Kara goto exit1; 3871b21996e3SJ. Bruce Fields retry_deleg: 38725955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3873f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38741da177e4SLinus Torvalds error = PTR_ERR(dentry); 38751da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38761da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3877f5beed75SAl Viro if (last.name[last.len]) 387850338b88STörök Edwin goto slashes; 38791da177e4SLinus Torvalds inode = dentry->d_inode; 3880b18825a7SDavid Howells if (d_is_negative(dentry)) 3881e6bc45d6STheodore Ts'o goto slashes; 38827de9c6eeSAl Viro ihold(inode); 3883f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3884be6d3e56SKentaro Takeda if (error) 3885c30dabfeSJan Kara goto exit2; 3886f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38871da177e4SLinus Torvalds exit2: 38881da177e4SLinus Torvalds dput(dentry); 38891da177e4SLinus Torvalds } 38905955102cSAl Viro inode_unlock(path.dentry->d_inode); 38911da177e4SLinus Torvalds if (inode) 38921da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3893b21996e3SJ. Bruce Fields inode = NULL; 3894b21996e3SJ. Bruce Fields if (delegated_inode) { 38955a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3896b21996e3SJ. Bruce Fields if (!error) 3897b21996e3SJ. Bruce Fields goto retry_deleg; 3898b21996e3SJ. Bruce Fields } 3899f5beed75SAl Viro mnt_drop_write(path.mnt); 39001da177e4SLinus Torvalds exit1: 3901f5beed75SAl Viro path_put(&path); 39025d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39035d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39045d18f813SJeff Layton inode = NULL; 39055d18f813SJeff Layton goto retry; 39065d18f813SJeff Layton } 3907da2f1362SChristoph Hellwig putname(name); 39081da177e4SLinus Torvalds return error; 39091da177e4SLinus Torvalds 39101da177e4SLinus Torvalds slashes: 3911b18825a7SDavid Howells if (d_is_negative(dentry)) 3912b18825a7SDavid Howells error = -ENOENT; 391344b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3914b18825a7SDavid Howells error = -EISDIR; 3915b18825a7SDavid Howells else 3916b18825a7SDavid Howells error = -ENOTDIR; 39171da177e4SLinus Torvalds goto exit2; 39181da177e4SLinus Torvalds } 39191da177e4SLinus Torvalds 39202e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39215590ff0dSUlrich Drepper { 39225590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39235590ff0dSUlrich Drepper return -EINVAL; 39245590ff0dSUlrich Drepper 39255590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39265590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39275590ff0dSUlrich Drepper 3928da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39295590ff0dSUlrich Drepper } 39305590ff0dSUlrich Drepper 39313480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39325590ff0dSUlrich Drepper { 3933da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39345590ff0dSUlrich Drepper } 39355590ff0dSUlrich Drepper 3936db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39371da177e4SLinus Torvalds { 3938a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39391da177e4SLinus Torvalds 39401da177e4SLinus Torvalds if (error) 39411da177e4SLinus Torvalds return error; 39421da177e4SLinus Torvalds 3943acfa4380SAl Viro if (!dir->i_op->symlink) 39441da177e4SLinus Torvalds return -EPERM; 39451da177e4SLinus Torvalds 39461da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39471da177e4SLinus Torvalds if (error) 39481da177e4SLinus Torvalds return error; 39491da177e4SLinus Torvalds 39501da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3951a74574aaSStephen Smalley if (!error) 3952f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39531da177e4SLinus Torvalds return error; 39541da177e4SLinus Torvalds } 39554d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39561da177e4SLinus Torvalds 3957b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 3958b724e846SDominik Brodowski const char __user *newname) 39591da177e4SLinus Torvalds { 39602ad94ae6SAl Viro int error; 396191a27b2aSJeff Layton struct filename *from; 39626902d925SDave Hansen struct dentry *dentry; 3963dae6ad8fSAl Viro struct path path; 3964f46d3567SJeff Layton unsigned int lookup_flags = 0; 39651da177e4SLinus Torvalds 39661da177e4SLinus Torvalds from = getname(oldname); 39671da177e4SLinus Torvalds if (IS_ERR(from)) 39681da177e4SLinus Torvalds return PTR_ERR(from); 3969f46d3567SJeff Layton retry: 3970f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39711da177e4SLinus Torvalds error = PTR_ERR(dentry); 39726902d925SDave Hansen if (IS_ERR(dentry)) 3973dae6ad8fSAl Viro goto out_putname; 39746902d925SDave Hansen 397591a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3976a8104a9fSAl Viro if (!error) 397791a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3978921a1650SAl Viro done_path_create(&path, dentry); 3979f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3980f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3981f46d3567SJeff Layton goto retry; 3982f46d3567SJeff Layton } 39836902d925SDave Hansen out_putname: 39841da177e4SLinus Torvalds putname(from); 39851da177e4SLinus Torvalds return error; 39861da177e4SLinus Torvalds } 39871da177e4SLinus Torvalds 3988b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 3989b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 3990b724e846SDominik Brodowski { 3991b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 3992b724e846SDominik Brodowski } 3993b724e846SDominik Brodowski 39943480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39955590ff0dSUlrich Drepper { 3996b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 39975590ff0dSUlrich Drepper } 39985590ff0dSUlrich Drepper 3999146a8595SJ. Bruce Fields /** 4000146a8595SJ. Bruce Fields * vfs_link - create a new link 4001146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4002146a8595SJ. Bruce Fields * @dir: new parent 4003146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4004146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4005146a8595SJ. Bruce Fields * 4006146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4007146a8595SJ. Bruce Fields * 4008146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4009146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4010146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4011146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4012146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4013146a8595SJ. Bruce Fields * 4014146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4015146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4016146a8595SJ. Bruce Fields * to be NFS exported. 4017146a8595SJ. Bruce Fields */ 4018146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40191da177e4SLinus Torvalds { 40201da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40218de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40221da177e4SLinus Torvalds int error; 40231da177e4SLinus Torvalds 40241da177e4SLinus Torvalds if (!inode) 40251da177e4SLinus Torvalds return -ENOENT; 40261da177e4SLinus Torvalds 4027a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40281da177e4SLinus Torvalds if (error) 40291da177e4SLinus Torvalds return error; 40301da177e4SLinus Torvalds 40311da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40321da177e4SLinus Torvalds return -EXDEV; 40331da177e4SLinus Torvalds 40341da177e4SLinus Torvalds /* 40351da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40361da177e4SLinus Torvalds */ 40371da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40381da177e4SLinus Torvalds return -EPERM; 40390bd23d09SEric W. Biederman /* 40400bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 40410bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 40420bd23d09SEric W. Biederman * the vfs. 40430bd23d09SEric W. Biederman */ 40440bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 40450bd23d09SEric W. Biederman return -EPERM; 4046acfa4380SAl Viro if (!dir->i_op->link) 40471da177e4SLinus Torvalds return -EPERM; 40487e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40491da177e4SLinus Torvalds return -EPERM; 40501da177e4SLinus Torvalds 40511da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40521da177e4SLinus Torvalds if (error) 40531da177e4SLinus Torvalds return error; 40541da177e4SLinus Torvalds 40555955102cSAl Viro inode_lock(inode); 4056aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4057f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4058aae8a97dSAneesh Kumar K.V error = -ENOENT; 40598de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40608de52778SAl Viro error = -EMLINK; 4061146a8595SJ. Bruce Fields else { 4062146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4063146a8595SJ. Bruce Fields if (!error) 40641da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4065146a8595SJ. Bruce Fields } 4066f4e0c30cSAl Viro 4067f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4068f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4069f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4070f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4071f4e0c30cSAl Viro } 40725955102cSAl Viro inode_unlock(inode); 4073e31e14ecSStephen Smalley if (!error) 40747e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40751da177e4SLinus Torvalds return error; 40761da177e4SLinus Torvalds } 40774d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40781da177e4SLinus Torvalds 40791da177e4SLinus Torvalds /* 40801da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40811da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40821da177e4SLinus Torvalds * newname. --KAB 40831da177e4SLinus Torvalds * 40841da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40851da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40861da177e4SLinus Torvalds * and other special files. --ADM 40871da177e4SLinus Torvalds */ 408846ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 408946ea89ebSDominik Brodowski const char __user *newname, int flags) 40901da177e4SLinus Torvalds { 40911da177e4SLinus Torvalds struct dentry *new_dentry; 4092dae6ad8fSAl Viro struct path old_path, new_path; 4093146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 409411a7b371SAneesh Kumar K.V int how = 0; 40951da177e4SLinus Torvalds int error; 40961da177e4SLinus Torvalds 409711a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4098c04030e1SUlrich Drepper return -EINVAL; 409911a7b371SAneesh Kumar K.V /* 4100f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4101f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4102f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 410311a7b371SAneesh Kumar K.V */ 4104f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4105f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4106f0cc6ffbSLinus Torvalds return -ENOENT; 410711a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4108f0cc6ffbSLinus Torvalds } 4109c04030e1SUlrich Drepper 411011a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 411111a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4112442e31caSJeff Layton retry: 411311a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41141da177e4SLinus Torvalds if (error) 41152ad94ae6SAl Viro return error; 41162ad94ae6SAl Viro 4117442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4118442e31caSJeff Layton (how & LOOKUP_REVAL)); 41191da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41206902d925SDave Hansen if (IS_ERR(new_dentry)) 4121dae6ad8fSAl Viro goto out; 4122dae6ad8fSAl Viro 4123dae6ad8fSAl Viro error = -EXDEV; 4124dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4125dae6ad8fSAl Viro goto out_dput; 4126800179c9SKees Cook error = may_linkat(&old_path); 4127800179c9SKees Cook if (unlikely(error)) 4128800179c9SKees Cook goto out_dput; 4129dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4130be6d3e56SKentaro Takeda if (error) 4131a8104a9fSAl Viro goto out_dput; 4132146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 413375c3f29dSDave Hansen out_dput: 4134921a1650SAl Viro done_path_create(&new_path, new_dentry); 4135146a8595SJ. Bruce Fields if (delegated_inode) { 4136146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4137d22e6338SOleg Drokin if (!error) { 4138d22e6338SOleg Drokin path_put(&old_path); 4139146a8595SJ. Bruce Fields goto retry; 4140146a8595SJ. Bruce Fields } 4141d22e6338SOleg Drokin } 4142442e31caSJeff Layton if (retry_estale(error, how)) { 4143d22e6338SOleg Drokin path_put(&old_path); 4144442e31caSJeff Layton how |= LOOKUP_REVAL; 4145442e31caSJeff Layton goto retry; 4146442e31caSJeff Layton } 41471da177e4SLinus Torvalds out: 41482d8f3038SAl Viro path_put(&old_path); 41491da177e4SLinus Torvalds 41501da177e4SLinus Torvalds return error; 41511da177e4SLinus Torvalds } 41521da177e4SLinus Torvalds 415346ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 415446ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 415546ea89ebSDominik Brodowski { 415646ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 415746ea89ebSDominik Brodowski } 415846ea89ebSDominik Brodowski 41593480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41605590ff0dSUlrich Drepper { 416146ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41625590ff0dSUlrich Drepper } 41635590ff0dSUlrich Drepper 4164bc27027aSMiklos Szeredi /** 4165bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4166bc27027aSMiklos Szeredi * @old_dir: parent of source 4167bc27027aSMiklos Szeredi * @old_dentry: source 4168bc27027aSMiklos Szeredi * @new_dir: parent of destination 4169bc27027aSMiklos Szeredi * @new_dentry: destination 4170bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4171520c8b16SMiklos Szeredi * @flags: rename flags 4172bc27027aSMiklos Szeredi * 4173bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4174bc27027aSMiklos Szeredi * 4175bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4176bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4177bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4178bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4179bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4180bc27027aSMiklos Szeredi * so. 4181bc27027aSMiklos Szeredi * 4182bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4183bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4184bc27027aSMiklos Szeredi * to be NFS exported. 4185bc27027aSMiklos Szeredi * 41861da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41871da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41881da177e4SLinus Torvalds * Problems: 41890117d427SMauro Carvalho Chehab * 4190d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41911da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41921da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4193a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41941da177e4SLinus Torvalds * story. 41956cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41966cedba89SJ. Bruce Fields * and source (if it is not a directory). 41971b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41981da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41991da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4200a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42011da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42021da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42031da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4204a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42051da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42061da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42071da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4208e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42091b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42101da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4211c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42121da177e4SLinus Torvalds * locking]. 42131da177e4SLinus Torvalds */ 42141da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42158e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4216520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42171da177e4SLinus Torvalds { 42181da177e4SLinus Torvalds int error; 4219bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4220bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4221bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4222da1ce067SMiklos Szeredi bool new_is_dir = false; 4223da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 422449d31c2fSAl Viro struct name_snapshot old_name; 42251da177e4SLinus Torvalds 42268d3e2936SMiklos Szeredi if (source == target) 42271da177e4SLinus Torvalds return 0; 42281da177e4SLinus Torvalds 42291da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42301da177e4SLinus Torvalds if (error) 42311da177e4SLinus Torvalds return error; 42321da177e4SLinus Torvalds 4233da1ce067SMiklos Szeredi if (!target) { 4234a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4235da1ce067SMiklos Szeredi } else { 4236da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4237da1ce067SMiklos Szeredi 4238da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42391da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4240da1ce067SMiklos Szeredi else 4241da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4242da1ce067SMiklos Szeredi } 42431da177e4SLinus Torvalds if (error) 42441da177e4SLinus Torvalds return error; 42451da177e4SLinus Torvalds 42462773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 42471da177e4SLinus Torvalds return -EPERM; 42481da177e4SLinus Torvalds 4249bc27027aSMiklos Szeredi /* 4250bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4251bc27027aSMiklos Szeredi * we'll need to flip '..'. 4252bc27027aSMiklos Szeredi */ 4253da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4254da1ce067SMiklos Szeredi if (is_dir) { 4255bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4256bc27027aSMiklos Szeredi if (error) 4257bc27027aSMiklos Szeredi return error; 4258bc27027aSMiklos Szeredi } 4259da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4260da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4261da1ce067SMiklos Szeredi if (error) 4262da1ce067SMiklos Szeredi return error; 4263da1ce067SMiklos Szeredi } 4264da1ce067SMiklos Szeredi } 42650eeca283SRobert Love 42660b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42670b3974ebSMiklos Szeredi flags); 4268bc27027aSMiklos Szeredi if (error) 4269bc27027aSMiklos Szeredi return error; 4270bc27027aSMiklos Szeredi 427149d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4272bc27027aSMiklos Szeredi dget(new_dentry); 4273da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4274bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4275bc27027aSMiklos Szeredi else if (target) 42765955102cSAl Viro inode_lock(target); 4277bc27027aSMiklos Szeredi 4278bc27027aSMiklos Szeredi error = -EBUSY; 42797af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4280bc27027aSMiklos Szeredi goto out; 4281bc27027aSMiklos Szeredi 4282da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4283bc27027aSMiklos Szeredi error = -EMLINK; 4284da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4285bc27027aSMiklos Szeredi goto out; 4286da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4287da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4288da1ce067SMiklos Szeredi goto out; 4289da1ce067SMiklos Szeredi } 4290da1ce067SMiklos Szeredi if (!is_dir) { 4291bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4292bc27027aSMiklos Szeredi if (error) 4293bc27027aSMiklos Szeredi goto out; 4294da1ce067SMiklos Szeredi } 4295da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4296bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4297bc27027aSMiklos Szeredi if (error) 4298bc27027aSMiklos Szeredi goto out; 4299bc27027aSMiklos Szeredi } 4300520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4301520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4302bc27027aSMiklos Szeredi if (error) 4303bc27027aSMiklos Szeredi goto out; 4304bc27027aSMiklos Szeredi 4305da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43068767712fSAl Viro if (is_dir) { 43078767712fSAl Viro shrink_dcache_parent(new_dentry); 4308bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43098767712fSAl Viro } 4310bc27027aSMiklos Szeredi dont_mount(new_dentry); 43118ed936b5SEric W. Biederman detach_mounts(new_dentry); 4312bc27027aSMiklos Szeredi } 4313da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4314da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4315bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4316da1ce067SMiklos Szeredi else 4317da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4318da1ce067SMiklos Szeredi } 4319bc27027aSMiklos Szeredi out: 4320da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4321bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4322bc27027aSMiklos Szeredi else if (target) 43235955102cSAl Viro inode_unlock(target); 4324bc27027aSMiklos Szeredi dput(new_dentry); 4325da1ce067SMiklos Szeredi if (!error) { 4326f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4327da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4328da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4329f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4330da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4331da1ce067SMiklos Szeredi } 4332da1ce067SMiklos Szeredi } 433349d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 43340eeca283SRobert Love 43351da177e4SLinus Torvalds return error; 43361da177e4SLinus Torvalds } 43374d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43381da177e4SLinus Torvalds 4339ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4340ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 43411da177e4SLinus Torvalds { 43421da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43431da177e4SLinus Torvalds struct dentry *trap; 4344f5beed75SAl Viro struct path old_path, new_path; 4345f5beed75SAl Viro struct qstr old_last, new_last; 4346f5beed75SAl Viro int old_type, new_type; 43478e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 434891a27b2aSJeff Layton struct filename *from; 434991a27b2aSJeff Layton struct filename *to; 4350f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4351c6a94284SJeff Layton bool should_retry = false; 43522ad94ae6SAl Viro int error; 4353520c8b16SMiklos Szeredi 43540d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4355da1ce067SMiklos Szeredi return -EINVAL; 4356da1ce067SMiklos Szeredi 43570d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43580d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4359520c8b16SMiklos Szeredi return -EINVAL; 4360520c8b16SMiklos Szeredi 43610d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43620d7a8555SMiklos Szeredi return -EPERM; 43630d7a8555SMiklos Szeredi 4364f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4365f5beed75SAl Viro target_flags = 0; 4366f5beed75SAl Viro 4367c6a94284SJeff Layton retry: 4368c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4369c1d4dd27SAl Viro &old_path, &old_last, &old_type); 437091a27b2aSJeff Layton if (IS_ERR(from)) { 437191a27b2aSJeff Layton error = PTR_ERR(from); 43721da177e4SLinus Torvalds goto exit; 437391a27b2aSJeff Layton } 43741da177e4SLinus Torvalds 4375c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4376c1d4dd27SAl Viro &new_path, &new_last, &new_type); 437791a27b2aSJeff Layton if (IS_ERR(to)) { 437891a27b2aSJeff Layton error = PTR_ERR(to); 43791da177e4SLinus Torvalds goto exit1; 438091a27b2aSJeff Layton } 43811da177e4SLinus Torvalds 43821da177e4SLinus Torvalds error = -EXDEV; 4383f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43841da177e4SLinus Torvalds goto exit2; 43851da177e4SLinus Torvalds 43861da177e4SLinus Torvalds error = -EBUSY; 4387f5beed75SAl Viro if (old_type != LAST_NORM) 43881da177e4SLinus Torvalds goto exit2; 43891da177e4SLinus Torvalds 43900a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43910a7c3937SMiklos Szeredi error = -EEXIST; 4392f5beed75SAl Viro if (new_type != LAST_NORM) 43931da177e4SLinus Torvalds goto exit2; 43941da177e4SLinus Torvalds 4395f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4396c30dabfeSJan Kara if (error) 4397c30dabfeSJan Kara goto exit2; 4398c30dabfeSJan Kara 43998e6d782cSJ. Bruce Fields retry_deleg: 4400f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44011da177e4SLinus Torvalds 4402f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44031da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44041da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44051da177e4SLinus Torvalds goto exit3; 44061da177e4SLinus Torvalds /* source must exist */ 44071da177e4SLinus Torvalds error = -ENOENT; 4408b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44091da177e4SLinus Torvalds goto exit4; 4410f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44111da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44121da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44131da177e4SLinus Torvalds goto exit4; 44140a7c3937SMiklos Szeredi error = -EEXIST; 44150a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44160a7c3937SMiklos Szeredi goto exit5; 4417da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4418da1ce067SMiklos Szeredi error = -ENOENT; 4419da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4420da1ce067SMiklos Szeredi goto exit5; 4421da1ce067SMiklos Szeredi 4422da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4423da1ce067SMiklos Szeredi error = -ENOTDIR; 4424f5beed75SAl Viro if (new_last.name[new_last.len]) 4425da1ce067SMiklos Szeredi goto exit5; 4426da1ce067SMiklos Szeredi } 4427da1ce067SMiklos Szeredi } 44280a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44290a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44300a7c3937SMiklos Szeredi error = -ENOTDIR; 4431f5beed75SAl Viro if (old_last.name[old_last.len]) 44320a7c3937SMiklos Szeredi goto exit5; 4433f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44340a7c3937SMiklos Szeredi goto exit5; 44350a7c3937SMiklos Szeredi } 44360a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44370a7c3937SMiklos Szeredi error = -EINVAL; 44380a7c3937SMiklos Szeredi if (old_dentry == trap) 44390a7c3937SMiklos Szeredi goto exit5; 44401da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4441da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44421da177e4SLinus Torvalds error = -ENOTEMPTY; 44431da177e4SLinus Torvalds if (new_dentry == trap) 44441da177e4SLinus Torvalds goto exit5; 44451da177e4SLinus Torvalds 4446f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4447f5beed75SAl Viro &new_path, new_dentry, flags); 4448be6d3e56SKentaro Takeda if (error) 4449c30dabfeSJan Kara goto exit5; 4450f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4451f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4452520c8b16SMiklos Szeredi &delegated_inode, flags); 44531da177e4SLinus Torvalds exit5: 44541da177e4SLinus Torvalds dput(new_dentry); 44551da177e4SLinus Torvalds exit4: 44561da177e4SLinus Torvalds dput(old_dentry); 44571da177e4SLinus Torvalds exit3: 4458f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44598e6d782cSJ. Bruce Fields if (delegated_inode) { 44608e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44618e6d782cSJ. Bruce Fields if (!error) 44628e6d782cSJ. Bruce Fields goto retry_deleg; 44638e6d782cSJ. Bruce Fields } 4464f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44651da177e4SLinus Torvalds exit2: 4466c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4467c6a94284SJeff Layton should_retry = true; 4468f5beed75SAl Viro path_put(&new_path); 44692ad94ae6SAl Viro putname(to); 44701da177e4SLinus Torvalds exit1: 4471f5beed75SAl Viro path_put(&old_path); 44721da177e4SLinus Torvalds putname(from); 4473c6a94284SJeff Layton if (should_retry) { 4474c6a94284SJeff Layton should_retry = false; 4475c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4476c6a94284SJeff Layton goto retry; 4477c6a94284SJeff Layton } 44782ad94ae6SAl Viro exit: 44791da177e4SLinus Torvalds return error; 44801da177e4SLinus Torvalds } 44811da177e4SLinus Torvalds 4482ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4483ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4484ee81feb6SDominik Brodowski { 4485ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4486ee81feb6SDominik Brodowski } 4487ee81feb6SDominik Brodowski 4488520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4489520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4490520c8b16SMiklos Szeredi { 4491ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4492520c8b16SMiklos Szeredi } 4493520c8b16SMiklos Szeredi 4494a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44955590ff0dSUlrich Drepper { 4496ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44975590ff0dSUlrich Drepper } 44985590ff0dSUlrich Drepper 4499787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4500787fb6bcSMiklos Szeredi { 4501787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4502787fb6bcSMiklos Szeredi if (error) 4503787fb6bcSMiklos Szeredi return error; 4504787fb6bcSMiklos Szeredi 4505787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4506787fb6bcSMiklos Szeredi return -EPERM; 4507787fb6bcSMiklos Szeredi 4508787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4509787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4510787fb6bcSMiklos Szeredi } 4511787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4512787fb6bcSMiklos Szeredi 45135d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45141da177e4SLinus Torvalds { 45155d826c84SAl Viro int len = PTR_ERR(link); 45161da177e4SLinus Torvalds if (IS_ERR(link)) 45171da177e4SLinus Torvalds goto out; 45181da177e4SLinus Torvalds 45191da177e4SLinus Torvalds len = strlen(link); 45201da177e4SLinus Torvalds if (len > (unsigned) buflen) 45211da177e4SLinus Torvalds len = buflen; 45221da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45231da177e4SLinus Torvalds len = -EFAULT; 45241da177e4SLinus Torvalds out: 45251da177e4SLinus Torvalds return len; 45261da177e4SLinus Torvalds } 45271da177e4SLinus Torvalds 4528d60874cdSMiklos Szeredi /** 4529fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4530fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4531fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4532fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4533fd4a0edfSMiklos Szeredi * 4534fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4535fd4a0edfSMiklos Szeredi * 4536fd4a0edfSMiklos Szeredi * Does not call security hook. 4537fd4a0edfSMiklos Szeredi */ 4538fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4539fd4a0edfSMiklos Szeredi { 4540fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4541f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4542f2df5da6SAl Viro const char *link; 4543f2df5da6SAl Viro int res; 4544fd4a0edfSMiklos Szeredi 454576fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 454676fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 454776fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 454876fca90eSMiklos Szeredi 454976fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4550fd4a0edfSMiklos Szeredi return -EINVAL; 4551fd4a0edfSMiklos Szeredi 455276fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 455376fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 455476fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 455576fca90eSMiklos Szeredi } 455676fca90eSMiklos Szeredi 45574c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4558f2df5da6SAl Viro if (!link) { 4559f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4560f2df5da6SAl Viro if (IS_ERR(link)) 4561f2df5da6SAl Viro return PTR_ERR(link); 4562f2df5da6SAl Viro } 4563f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4564f2df5da6SAl Viro do_delayed_call(&done); 4565f2df5da6SAl Viro return res; 4566fd4a0edfSMiklos Szeredi } 4567fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 45681da177e4SLinus Torvalds 4569d60874cdSMiklos Szeredi /** 4570d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4571d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4572d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4573d60874cdSMiklos Szeredi * 4574d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4575d60874cdSMiklos Szeredi * 4576d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4577d60874cdSMiklos Szeredi * 4578d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4579d60874cdSMiklos Szeredi */ 4580d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4581d60874cdSMiklos Szeredi { 4582d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4583d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4584d60874cdSMiklos Szeredi 4585d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4586d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4587d60874cdSMiklos Szeredi if (!res) 4588d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4589d60874cdSMiklos Szeredi } 4590d60874cdSMiklos Szeredi return res; 4591d60874cdSMiklos Szeredi } 4592d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4593d60874cdSMiklos Szeredi 45941da177e4SLinus Torvalds /* get the link contents into pagecache */ 45956b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4596fceef393SAl Viro struct delayed_call *callback) 45971da177e4SLinus Torvalds { 4598ebd09abbSDuane Griffin char *kaddr; 45991da177e4SLinus Torvalds struct page *page; 46006b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46016b255391SAl Viro 4602d3883d4fSAl Viro if (!dentry) { 4603d3883d4fSAl Viro page = find_get_page(mapping, 0); 4604d3883d4fSAl Viro if (!page) 46056b255391SAl Viro return ERR_PTR(-ECHILD); 4606d3883d4fSAl Viro if (!PageUptodate(page)) { 4607d3883d4fSAl Viro put_page(page); 4608d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4609d3883d4fSAl Viro } 4610d3883d4fSAl Viro } else { 4611090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46121da177e4SLinus Torvalds if (IS_ERR(page)) 46136fe6900eSNick Piggin return (char*)page; 4614d3883d4fSAl Viro } 4615fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 461621fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 461721fc61c7SAl Viro kaddr = page_address(page); 46186b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4619ebd09abbSDuane Griffin return kaddr; 46201da177e4SLinus Torvalds } 46211da177e4SLinus Torvalds 46226b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46231da177e4SLinus Torvalds 4624fceef393SAl Viro void page_put_link(void *arg) 46251da177e4SLinus Torvalds { 4626fceef393SAl Viro put_page(arg); 46271da177e4SLinus Torvalds } 46284d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46291da177e4SLinus Torvalds 4630aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4631aa80deabSAl Viro { 4632fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46336b255391SAl Viro int res = readlink_copy(buffer, buflen, 46346b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4635fceef393SAl Viro &done)); 4636fceef393SAl Viro do_delayed_call(&done); 4637aa80deabSAl Viro return res; 4638aa80deabSAl Viro } 4639aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4640aa80deabSAl Viro 464154566b2cSNick Piggin /* 464254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 464354566b2cSNick Piggin */ 464454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46451da177e4SLinus Torvalds { 46461da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46470adb25d2SKirill Korotaev struct page *page; 4648afddba49SNick Piggin void *fsdata; 4649beb497abSDmitriy Monakhov int err; 4650c718a975STetsuo Handa unsigned int flags = 0; 465154566b2cSNick Piggin if (nofs) 465254566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46531da177e4SLinus Torvalds 46547e53cac4SNeilBrown retry: 4655afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 465654566b2cSNick Piggin flags, &page, &fsdata); 46571da177e4SLinus Torvalds if (err) 4658afddba49SNick Piggin goto fail; 4659afddba49SNick Piggin 466021fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4661afddba49SNick Piggin 4662afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4663afddba49SNick Piggin page, fsdata); 46641da177e4SLinus Torvalds if (err < 0) 46651da177e4SLinus Torvalds goto fail; 4666afddba49SNick Piggin if (err < len-1) 4667afddba49SNick Piggin goto retry; 4668afddba49SNick Piggin 46691da177e4SLinus Torvalds mark_inode_dirty(inode); 46701da177e4SLinus Torvalds return 0; 46711da177e4SLinus Torvalds fail: 46721da177e4SLinus Torvalds return err; 46731da177e4SLinus Torvalds } 46744d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46751da177e4SLinus Torvalds 46760adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46770adb25d2SKirill Korotaev { 46780adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4679c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 46800adb25d2SKirill Korotaev } 46814d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46820adb25d2SKirill Korotaev 468392e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46846b255391SAl Viro .get_link = page_get_link, 46851da177e4SLinus Torvalds }; 46861da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4687