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 */ 6082aa38470SAl Viro static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq) 6097973387aSAl Viro { 6102aa38470SAl Viro int res = __legitimize_mnt(path->mnt, mseq); 6117973387aSAl Viro if (unlikely(res)) { 6127973387aSAl Viro if (res > 0) 6137973387aSAl Viro path->mnt = NULL; 6147973387aSAl Viro path->dentry = NULL; 6157973387aSAl Viro return false; 6167973387aSAl Viro } 6177973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6227973387aSAl Viro } 6237973387aSAl Viro 6242aa38470SAl Viro static inline bool legitimize_path(struct nameidata *nd, 6252aa38470SAl Viro struct path *path, unsigned seq) 6262aa38470SAl Viro { 6272aa38470SAl Viro return __legitimize_path(path, nd->m_seq, seq); 6282aa38470SAl Viro } 6292aa38470SAl Viro 6307973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6317973387aSAl Viro { 6327973387aSAl Viro int i; 6337973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6347973387aSAl Viro struct saved *last = nd->stack + i; 6357973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6367973387aSAl Viro drop_links(nd); 6377973387aSAl Viro nd->depth = i + 1; 6387973387aSAl Viro return false; 6397973387aSAl Viro } 6407973387aSAl Viro } 6417973387aSAl Viro return true; 6427973387aSAl Viro } 6437973387aSAl Viro 644ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 645ee594bffSAl Viro { 646adb21d2bSAleksa Sarai /* 647adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 648adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 649adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 650adb21d2bSAleksa Sarai */ 651adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 652adb21d2bSAleksa Sarai return false; 653adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 654ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 655ee594bffSAl Viro return true; 65684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 657ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 658ee594bffSAl Viro } 659ee594bffSAl Viro 66019660af7SAl Viro /* 66131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66931e6b01fSNick Piggin */ 67031e6b01fSNick Piggin 67131e6b01fSNick Piggin /** 67219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67319660af7SAl Viro * @nd: nameidata pathwalk data 67439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67531e6b01fSNick Piggin * 6764675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6774675ac39SAl Viro * for ref-walk mode. 6784675ac39SAl Viro * Must be called from rcu-walk context. 6797973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6807973387aSAl Viro * terminate_walk(). 68131e6b01fSNick Piggin */ 6824675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68331e6b01fSNick Piggin { 68431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68531e6b01fSNick Piggin 68631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 687e5c832d5SLinus Torvalds 688e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6897973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6904675ac39SAl Viro goto out1; 69184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 69284a2bd39SAl Viro goto out; 693ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6944675ac39SAl Viro goto out; 6954675ac39SAl Viro rcu_read_unlock(); 6964675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6974675ac39SAl Viro return 0; 6984675ac39SAl Viro 69984a2bd39SAl Viro out1: 7004675ac39SAl Viro nd->path.mnt = NULL; 7014675ac39SAl Viro nd->path.dentry = NULL; 7024675ac39SAl Viro out: 7034675ac39SAl Viro rcu_read_unlock(); 7044675ac39SAl Viro return -ECHILD; 7054675ac39SAl Viro } 7064675ac39SAl Viro 7074675ac39SAl Viro /** 7084675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7094675ac39SAl Viro * @nd: nameidata pathwalk data 7104675ac39SAl Viro * @dentry: child of nd->path.dentry 7114675ac39SAl Viro * @seq: seq number to check dentry against 7124675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7134675ac39SAl Viro * 7144675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7154675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7164675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7174675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7184675ac39SAl Viro * terminate_walk(). 7194675ac39SAl Viro */ 7204675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7214675ac39SAl Viro { 7224675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7234675ac39SAl Viro 7244675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7254675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7264675ac39SAl Viro goto out2; 7277973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7287973387aSAl Viro goto out2; 7294675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7307973387aSAl Viro goto out1; 73148a066e7SAl Viro 73215570086SLinus Torvalds /* 7334675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7344675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7354675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7364675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7374675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73815570086SLinus Torvalds */ 7394675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 740e5c832d5SLinus Torvalds goto out; 74184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 74284a2bd39SAl Viro goto out_dput; 743e5c832d5SLinus Torvalds /* 744e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 745e5c832d5SLinus Torvalds * still valid and get it if required. 746e5c832d5SLinus Torvalds */ 74784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74884a2bd39SAl Viro goto out_dput; 7498b61e74fSAl Viro rcu_read_unlock(); 75031e6b01fSNick Piggin return 0; 75119660af7SAl Viro 7527973387aSAl Viro out2: 7537973387aSAl Viro nd->path.mnt = NULL; 7547973387aSAl Viro out1: 7557973387aSAl Viro nd->path.dentry = NULL; 756e5c832d5SLinus Torvalds out: 7578b61e74fSAl Viro rcu_read_unlock(); 75884a2bd39SAl Viro return -ECHILD; 75984a2bd39SAl Viro out_dput: 76084a2bd39SAl Viro rcu_read_unlock(); 76184a2bd39SAl Viro dput(dentry); 76231e6b01fSNick Piggin return -ECHILD; 76331e6b01fSNick Piggin } 76431e6b01fSNick Piggin 7654ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76634286d66SNick Piggin { 767a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7684ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 769a89f8337SAl Viro else 770a89f8337SAl Viro return 1; 77134286d66SNick Piggin } 77234286d66SNick Piggin 7739f1fafeeSAl Viro /** 7749f1fafeeSAl Viro * complete_walk - successful completion of path walk 7759f1fafeeSAl Viro * @nd: pointer nameidata 77639159de2SJeff Layton * 7779f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7789f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7799f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7809f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7819f1fafeeSAl Viro * need to drop nd->path. 78239159de2SJeff Layton */ 7839f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78439159de2SJeff Layton { 78516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78639159de2SJeff Layton int status; 78739159de2SJeff Layton 7889f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 789adb21d2bSAleksa Sarai /* 790adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 791adb21d2bSAleksa Sarai * externally-managed nd->root. 792adb21d2bSAleksa Sarai */ 793adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7949f1fafeeSAl Viro nd->root.mnt = NULL; 7954675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79648a066e7SAl Viro return -ECHILD; 79748a066e7SAl Viro } 7989f1fafeeSAl Viro 799adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 800adb21d2bSAleksa Sarai /* 801adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 802adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 803adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 804adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 805adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 806adb21d2bSAleksa Sarai * 807adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 808adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 809adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 810adb21d2bSAleksa Sarai * requested root to userspace. 811adb21d2bSAleksa Sarai * 812adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 813adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 814adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 815adb21d2bSAleksa Sarai */ 816adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 817adb21d2bSAleksa Sarai return -EXDEV; 818adb21d2bSAleksa Sarai } 819adb21d2bSAleksa Sarai 82016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 82139159de2SJeff Layton return 0; 82239159de2SJeff Layton 823ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 82416c2cd71SAl Viro return 0; 82516c2cd71SAl Viro 826ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82739159de2SJeff Layton if (status > 0) 82839159de2SJeff Layton return 0; 82939159de2SJeff Layton 83016c2cd71SAl Viro if (!status) 83139159de2SJeff Layton status = -ESTALE; 83216c2cd71SAl Viro 83339159de2SJeff Layton return status; 83439159de2SJeff Layton } 83539159de2SJeff Layton 836740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8372a737871SAl Viro { 83831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8399e6697e2SAl Viro 840adb21d2bSAleksa Sarai /* 841adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 842adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 843adb21d2bSAleksa Sarai * from the dirfd. 844adb21d2bSAleksa Sarai */ 845adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 846adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 847adb21d2bSAleksa Sarai 8489e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8498f47a016SAl Viro unsigned seq; 850c28cc364SNick Piggin 851c28cc364SNick Piggin do { 852c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 85331e6b01fSNick Piggin nd->root = fs->root; 8548f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 855c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8569e6697e2SAl Viro } else { 8579e6697e2SAl Viro get_fs_root(fs, &nd->root); 85884a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8599e6697e2SAl Viro } 860740a1678SAleksa Sarai return 0; 86131e6b01fSNick Piggin } 86231e6b01fSNick Piggin 8637b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8647b9337aaSNick Piggin struct nameidata *nd) 865051d3812SIan Kent { 86631e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8674ac91378SJan Blunck dput(nd->path.dentry); 86831e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8694ac91378SJan Blunck mntput(nd->path.mnt); 8709a229683SHuang Shijie } 87131e6b01fSNick Piggin nd->path.mnt = path->mnt; 8724ac91378SJan Blunck nd->path.dentry = path->dentry; 873051d3812SIan Kent } 874051d3812SIan Kent 875248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 876248fb5b9SAl Viro { 877adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 878adb21d2bSAleksa Sarai return -EXDEV; 87972ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 88072ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 88172ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 88272ba2929SAleksa Sarai return -EXDEV; 88372ba2929SAleksa Sarai } 884740a1678SAleksa Sarai if (!nd->root.mnt) { 885740a1678SAleksa Sarai int error = set_root(nd); 886740a1678SAleksa Sarai if (error) 887740a1678SAleksa Sarai return error; 888740a1678SAleksa Sarai } 889248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 890248fb5b9SAl Viro struct dentry *d; 891248fb5b9SAl Viro nd->path = nd->root; 892248fb5b9SAl Viro d = nd->path.dentry; 893248fb5b9SAl Viro nd->inode = d->d_inode; 894248fb5b9SAl Viro nd->seq = nd->root_seq; 895248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 896248fb5b9SAl Viro return -ECHILD; 897248fb5b9SAl Viro } else { 898248fb5b9SAl Viro path_put(&nd->path); 899248fb5b9SAl Viro nd->path = nd->root; 900248fb5b9SAl Viro path_get(&nd->path); 901248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 902248fb5b9SAl Viro } 903248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 904248fb5b9SAl Viro return 0; 905248fb5b9SAl Viro } 906248fb5b9SAl Viro 907b5fb63c1SChristoph Hellwig /* 9086b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 909b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 910b5fb63c1SChristoph Hellwig */ 9111bc82070SAleksa Sarai int nd_jump_link(struct path *path) 912b5fb63c1SChristoph Hellwig { 9134b99d499SAleksa Sarai int error = -ELOOP; 9146e77137bSAl Viro struct nameidata *nd = current->nameidata; 915b5fb63c1SChristoph Hellwig 9164b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9174b99d499SAleksa Sarai goto err; 9184b99d499SAleksa Sarai 91972ba2929SAleksa Sarai error = -EXDEV; 92072ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 92172ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 92272ba2929SAleksa Sarai goto err; 92372ba2929SAleksa Sarai } 924adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 925adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 926adb21d2bSAleksa Sarai goto err; 92772ba2929SAleksa Sarai 9284b99d499SAleksa Sarai path_put(&nd->path); 929b5fb63c1SChristoph Hellwig nd->path = *path; 930b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 931b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9321bc82070SAleksa Sarai return 0; 9334b99d499SAleksa Sarai 9344b99d499SAleksa Sarai err: 9354b99d499SAleksa Sarai path_put(path); 9364b99d499SAleksa Sarai return error; 937b5fb63c1SChristoph Hellwig } 938b5fb63c1SChristoph Hellwig 939b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 940574197e0SAl Viro { 94121c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 942fceef393SAl Viro do_delayed_call(&last->done); 9436548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 944b9ff4429SAl Viro path_put(&last->link); 945574197e0SAl Viro } 946574197e0SAl Viro 947561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 948561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 94930aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 95030aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 951800179c9SKees Cook 952800179c9SKees Cook /** 953800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 95455852635SRandy Dunlap * @nd: nameidata pathwalk data 955800179c9SKees Cook * 956800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 957800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 958800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 959800179c9SKees Cook * processes from failing races against path names that may change out 960800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 961800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 962800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 963800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 964800179c9SKees Cook * 965800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 966800179c9SKees Cook */ 967ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 968800179c9SKees Cook { 969800179c9SKees Cook const struct inode *parent; 9702d7f9e2aSSeth Forshee kuid_t puid; 971800179c9SKees Cook 972800179c9SKees Cook if (!sysctl_protected_symlinks) 973800179c9SKees Cook return 0; 974800179c9SKees Cook 975800179c9SKees Cook /* Allowed if owner and follower match. */ 97681abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 977800179c9SKees Cook return 0; 978800179c9SKees Cook 979800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 980aa65fa35SAl Viro parent = nd->inode; 981800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 982800179c9SKees Cook return 0; 983800179c9SKees Cook 984800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9852d7f9e2aSSeth Forshee puid = parent->i_uid; 9862d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 987800179c9SKees Cook return 0; 988800179c9SKees Cook 98931956502SAl Viro if (nd->flags & LOOKUP_RCU) 99031956502SAl Viro return -ECHILD; 99131956502SAl Viro 992ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 993245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 994800179c9SKees Cook return -EACCES; 995800179c9SKees Cook } 996800179c9SKees Cook 997800179c9SKees Cook /** 998800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 999800179c9SKees Cook * @inode: the source inode to hardlink from 1000800179c9SKees Cook * 1001800179c9SKees Cook * Return false if at least one of the following conditions: 1002800179c9SKees Cook * - inode is not a regular file 1003800179c9SKees Cook * - inode is setuid 1004800179c9SKees Cook * - inode is setgid and group-exec 1005800179c9SKees Cook * - access failure for read and write 1006800179c9SKees Cook * 1007800179c9SKees Cook * Otherwise returns true. 1008800179c9SKees Cook */ 1009800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1010800179c9SKees Cook { 1011800179c9SKees Cook umode_t mode = inode->i_mode; 1012800179c9SKees Cook 1013800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1014800179c9SKees Cook if (!S_ISREG(mode)) 1015800179c9SKees Cook return false; 1016800179c9SKees Cook 1017800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1018800179c9SKees Cook if (mode & S_ISUID) 1019800179c9SKees Cook return false; 1020800179c9SKees Cook 1021800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1022800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1023800179c9SKees Cook return false; 1024800179c9SKees Cook 1025800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1026800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1027800179c9SKees Cook return false; 1028800179c9SKees Cook 1029800179c9SKees Cook return true; 1030800179c9SKees Cook } 1031800179c9SKees Cook 1032800179c9SKees Cook /** 1033800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1034800179c9SKees Cook * @link: the source to hardlink from 1035800179c9SKees Cook * 1036800179c9SKees Cook * Block hardlink when all of: 1037800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1038800179c9SKees Cook * - fsuid does not match inode 1039800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1040f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1041800179c9SKees Cook * 1042800179c9SKees Cook * Returns 0 if successful, -ve on error. 1043800179c9SKees Cook */ 1044800179c9SKees Cook static int may_linkat(struct path *link) 1045800179c9SKees Cook { 1046593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1047593d1ce8SEric W. Biederman 1048593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1049593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1050593d1ce8SEric W. Biederman return -EOVERFLOW; 1051800179c9SKees Cook 1052800179c9SKees Cook if (!sysctl_protected_hardlinks) 1053800179c9SKees Cook return 0; 1054800179c9SKees Cook 1055800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1056800179c9SKees Cook * otherwise, it must be a safe source. 1057800179c9SKees Cook */ 1058cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1059800179c9SKees Cook return 0; 1060800179c9SKees Cook 1061245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1062800179c9SKees Cook return -EPERM; 1063800179c9SKees Cook } 1064800179c9SKees Cook 106530aba665SSalvatore Mesoraca /** 106630aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 106730aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 106830aba665SSalvatore Mesoraca * exist. 1069d0cb5018SAl Viro * @dir_mode: mode bits of directory 1070d0cb5018SAl Viro * @dir_uid: owner of directory 107130aba665SSalvatore Mesoraca * @inode: the inode of the file to open 107230aba665SSalvatore Mesoraca * 107330aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 107430aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 107530aba665SSalvatore Mesoraca * - the file already exists 107630aba665SSalvatore Mesoraca * - we are in a sticky directory 107730aba665SSalvatore Mesoraca * - we don't own the file 107830aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 107930aba665SSalvatore Mesoraca * - the directory is world writable 108030aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 108130aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 108230aba665SSalvatore Mesoraca * be enough. 108330aba665SSalvatore Mesoraca * 108430aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 108530aba665SSalvatore Mesoraca */ 1086d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 108730aba665SSalvatore Mesoraca struct inode * const inode) 108830aba665SSalvatore Mesoraca { 108930aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 109030aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1091d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1092d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 109330aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 109430aba665SSalvatore Mesoraca return 0; 109530aba665SSalvatore Mesoraca 1096d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1097d0cb5018SAl Viro (dir_mode & 0020 && 109830aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 109930aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1100245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1101245d7369SKees Cook "sticky_create_fifo" : 1102245d7369SKees Cook "sticky_create_regular"; 1103245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 110430aba665SSalvatore Mesoraca return -EACCES; 110530aba665SSalvatore Mesoraca } 110630aba665SSalvatore Mesoraca return 0; 110730aba665SSalvatore Mesoraca } 110830aba665SSalvatore Mesoraca 1109f015f126SDavid Howells /* 1110f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1111f015f126SDavid Howells * 1112f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1113f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1114f015f126SDavid Howells * Up is towards /. 1115f015f126SDavid Howells * 1116f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1117f015f126SDavid Howells * root. 1118f015f126SDavid Howells */ 1119bab77ebfSAl Viro int follow_up(struct path *path) 11201da177e4SLinus Torvalds { 11210714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11220714a533SAl Viro struct mount *parent; 11231da177e4SLinus Torvalds struct dentry *mountpoint; 112499b7db7bSNick Piggin 112548a066e7SAl Viro read_seqlock_excl(&mount_lock); 11260714a533SAl Viro parent = mnt->mnt_parent; 11273c0a6163SAl Viro if (parent == mnt) { 112848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11291da177e4SLinus Torvalds return 0; 11301da177e4SLinus Torvalds } 11310714a533SAl Viro mntget(&parent->mnt); 1132a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 113348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1134bab77ebfSAl Viro dput(path->dentry); 1135bab77ebfSAl Viro path->dentry = mountpoint; 1136bab77ebfSAl Viro mntput(path->mnt); 11370714a533SAl Viro path->mnt = &parent->mnt; 11381da177e4SLinus Torvalds return 1; 11391da177e4SLinus Torvalds } 11404d359507SAl Viro EXPORT_SYMBOL(follow_up); 11411da177e4SLinus Torvalds 11427ef482faSAl Viro static bool choose_mountpoint_rcu(struct mount *m, const struct path *root, 11437ef482faSAl Viro struct path *path, unsigned *seqp) 11447ef482faSAl Viro { 11457ef482faSAl Viro while (mnt_has_parent(m)) { 11467ef482faSAl Viro struct dentry *mountpoint = m->mnt_mountpoint; 11477ef482faSAl Viro 11487ef482faSAl Viro m = m->mnt_parent; 11497ef482faSAl Viro if (unlikely(root->dentry == mountpoint && 11507ef482faSAl Viro root->mnt == &m->mnt)) 11517ef482faSAl Viro break; 11527ef482faSAl Viro if (mountpoint != m->mnt.mnt_root) { 11537ef482faSAl Viro path->mnt = &m->mnt; 11547ef482faSAl Viro path->dentry = mountpoint; 11557ef482faSAl Viro *seqp = read_seqcount_begin(&mountpoint->d_seq); 11567ef482faSAl Viro return true; 11577ef482faSAl Viro } 11587ef482faSAl Viro } 11597ef482faSAl Viro return false; 11607ef482faSAl Viro } 11617ef482faSAl Viro 11622aa38470SAl Viro static bool choose_mountpoint(struct mount *m, const struct path *root, 11632aa38470SAl Viro struct path *path) 11642aa38470SAl Viro { 11652aa38470SAl Viro bool found; 11662aa38470SAl Viro 11672aa38470SAl Viro rcu_read_lock(); 11682aa38470SAl Viro while (1) { 11692aa38470SAl Viro unsigned seq, mseq = read_seqbegin(&mount_lock); 11702aa38470SAl Viro 11712aa38470SAl Viro found = choose_mountpoint_rcu(m, root, path, &seq); 11722aa38470SAl Viro if (unlikely(!found)) { 11732aa38470SAl Viro if (!read_seqretry(&mount_lock, mseq)) 11742aa38470SAl Viro break; 11752aa38470SAl Viro } else { 11762aa38470SAl Viro if (likely(__legitimize_path(path, seq, mseq))) 11772aa38470SAl Viro break; 11782aa38470SAl Viro rcu_read_unlock(); 11792aa38470SAl Viro path_put(path); 11802aa38470SAl Viro rcu_read_lock(); 11812aa38470SAl Viro } 11822aa38470SAl Viro } 11832aa38470SAl Viro rcu_read_unlock(); 11842aa38470SAl Viro return found; 11852aa38470SAl Viro } 11862aa38470SAl Viro 1187b5c84bf6SNick Piggin /* 11889875cf80SDavid Howells * Perform an automount 11899875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11909875cf80SDavid Howells * were called with. 11911da177e4SLinus Torvalds */ 11921c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 119331e6b01fSNick Piggin { 119425e195aaSAl Viro struct dentry *dentry = path->dentry; 11959875cf80SDavid Howells 11960ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11970ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11980ec26fd0SMiklos Szeredi * the name. 11990ec26fd0SMiklos Szeredi * 12000ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 12015a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 12020ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 12030ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 12040ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 12050ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 12065a30d8a2SDavid Howells */ 12071c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 12085d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 120925e195aaSAl Viro dentry->d_inode) 12109875cf80SDavid Howells return -EISDIR; 12110ec26fd0SMiklos Szeredi 12121c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 12139875cf80SDavid Howells return -ELOOP; 12149875cf80SDavid Howells 121525e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1216ea5b778aSDavid Howells } 12179875cf80SDavid Howells 12189875cf80SDavid Howells /* 12199deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 12209deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 12219deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 12229deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 12239875cf80SDavid Howells */ 12249deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 12259deed3ebSAl Viro int *count, unsigned lookup_flags) 12269875cf80SDavid Howells { 12279deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 12289875cf80SDavid Howells bool need_mntput = false; 12298aef1884SAl Viro int ret = 0; 12309875cf80SDavid Howells 12319deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1232cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1233cc53ce53SDavid Howells * being held. */ 1234d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1235fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1236508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1237cc53ce53SDavid Howells if (ret < 0) 12388aef1884SAl Viro break; 1239cc53ce53SDavid Howells } 1240cc53ce53SDavid Howells 12419deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 12429875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12439deed3ebSAl Viro if (mounted) { // ... in our namespace 12449875cf80SDavid Howells dput(path->dentry); 12459875cf80SDavid Howells if (need_mntput) 1246463ffb2eSAl Viro mntput(path->mnt); 1247463ffb2eSAl Viro path->mnt = mounted; 1248463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12499deed3ebSAl Viro // here we know it's positive 12509deed3ebSAl Viro flags = path->dentry->d_flags; 12519875cf80SDavid Howells need_mntput = true; 12529875cf80SDavid Howells continue; 1253463ffb2eSAl Viro } 12541da177e4SLinus Torvalds } 12559875cf80SDavid Howells 12569deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 12579deed3ebSAl Viro break; 12589deed3ebSAl Viro 12599deed3ebSAl Viro // uncovered automount point 12609deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 12619deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 12629875cf80SDavid Howells if (ret < 0) 12638aef1884SAl Viro break; 12649875cf80SDavid Howells } 12659875cf80SDavid Howells 12669deed3ebSAl Viro if (ret == -EISDIR) 12679deed3ebSAl Viro ret = 0; 12689deed3ebSAl Viro // possible if you race with several mount --move 12699deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 12708aef1884SAl Viro mntput(path->mnt); 12719deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1272d41efb52SAl Viro ret = -ENOENT; 12739deed3ebSAl Viro *jumped = need_mntput; 12748402752eSAl Viro return ret; 12751da177e4SLinus Torvalds } 12761da177e4SLinus Torvalds 12779deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 12789deed3ebSAl Viro int *count, unsigned lookup_flags) 12799deed3ebSAl Viro { 12809deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 12819deed3ebSAl Viro 12829deed3ebSAl Viro /* fastpath */ 12839deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 12849deed3ebSAl Viro *jumped = false; 12859deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 12869deed3ebSAl Viro return -ENOENT; 12879deed3ebSAl Viro return 0; 12889deed3ebSAl Viro } 12899deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 12909deed3ebSAl Viro } 12919deed3ebSAl Viro 1292cc53ce53SDavid Howells int follow_down_one(struct path *path) 12931da177e4SLinus Torvalds { 12941da177e4SLinus Torvalds struct vfsmount *mounted; 12951da177e4SLinus Torvalds 12961c755af4SAl Viro mounted = lookup_mnt(path); 12971da177e4SLinus Torvalds if (mounted) { 12989393bd07SAl Viro dput(path->dentry); 12999393bd07SAl Viro mntput(path->mnt); 13009393bd07SAl Viro path->mnt = mounted; 13019393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 13021da177e4SLinus Torvalds return 1; 13031da177e4SLinus Torvalds } 13041da177e4SLinus Torvalds return 0; 13051da177e4SLinus Torvalds } 13064d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 13071da177e4SLinus Torvalds 13089875cf80SDavid Howells /* 13099deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 13109deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 13119deed3ebSAl Viro * caller is permitted to proceed or not. 13129deed3ebSAl Viro */ 13139deed3ebSAl Viro int follow_down(struct path *path) 13149deed3ebSAl Viro { 13159deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 13169deed3ebSAl Viro bool jumped; 13179deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 13189deed3ebSAl Viro 13199deed3ebSAl Viro if (path->mnt != mnt) 13209deed3ebSAl Viro mntput(mnt); 13219deed3ebSAl Viro return ret; 13229deed3ebSAl Viro } 13239deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 13249deed3ebSAl Viro 13259deed3ebSAl Viro /* 1326287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1327287548e4SAl Viro * we meet a managed dentry that would need blocking. 13289875cf80SDavid Howells */ 13299875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1330254cf582SAl Viro struct inode **inode, unsigned *seqp) 13319875cf80SDavid Howells { 1332ea936aebSAl Viro struct dentry *dentry = path->dentry; 1333ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1334ea936aebSAl Viro 1335ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1336ea936aebSAl Viro return true; 1337ea936aebSAl Viro 1338ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1339ea936aebSAl Viro return false; 1340ea936aebSAl Viro 134162a7375eSIan Kent for (;;) { 134262a7375eSIan Kent /* 134362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 134462a7375eSIan Kent * that wants to block transit. 134562a7375eSIan Kent */ 1346ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1347ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1348ea936aebSAl Viro if (res) 1349ea936aebSAl Viro return res == -EISDIR; 1350ea936aebSAl Viro flags = dentry->d_flags; 1351b8faf035SNeilBrown } 135262a7375eSIan Kent 1353ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1354ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1355ea936aebSAl Viro if (mounted) { 1356c7105365SAl Viro path->mnt = &mounted->mnt; 1357ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1358a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1359ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1360ea936aebSAl Viro *inode = dentry->d_inode; 136159430262SLinus Torvalds /* 1362ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1363ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1364ea936aebSAl Viro * between mount hash removal and ->mnt_root 1365ea936aebSAl Viro * becoming unpinned. 136659430262SLinus Torvalds */ 1367ea936aebSAl Viro flags = dentry->d_flags; 1368ea936aebSAl Viro continue; 13699875cf80SDavid Howells } 1370ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1371ea936aebSAl Viro return false; 1372ea936aebSAl Viro } 1373ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1374ea936aebSAl Viro } 1375287548e4SAl Viro } 1376287548e4SAl Viro 1377db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1378db3c9adeSAl Viro struct path *path, struct inode **inode, 1379db3c9adeSAl Viro unsigned int *seqp) 1380bd7c4b50SAl Viro { 13819deed3ebSAl Viro bool jumped; 1382db3c9adeSAl Viro int ret; 1383bd7c4b50SAl Viro 1384db3c9adeSAl Viro path->mnt = nd->path.mnt; 1385db3c9adeSAl Viro path->dentry = dentry; 1386c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1387c153007bSAl Viro unsigned int seq = *seqp; 1388c153007bSAl Viro if (unlikely(!*inode)) 1389c153007bSAl Viro return -ENOENT; 1390c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 13919deed3ebSAl Viro return 0; 1392c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1393c153007bSAl Viro return -ECHILD; 1394c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1395c153007bSAl Viro path->mnt = nd->path.mnt; 1396c153007bSAl Viro path->dentry = dentry; 1397c153007bSAl Viro } 13989deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 13999deed3ebSAl Viro if (jumped) { 14009deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 14019deed3ebSAl Viro ret = -EXDEV; 14029deed3ebSAl Viro else 14039deed3ebSAl Viro nd->flags |= LOOKUP_JUMPED; 14049deed3ebSAl Viro } 14059deed3ebSAl Viro if (unlikely(ret)) { 14069deed3ebSAl Viro dput(path->dentry); 14079deed3ebSAl Viro if (path->mnt != nd->path.mnt) 14089deed3ebSAl Viro mntput(path->mnt); 14099deed3ebSAl Viro } else { 1410bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1411bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1412bd7c4b50SAl Viro } 1413bd7c4b50SAl Viro return ret; 1414bd7c4b50SAl Viro } 1415bd7c4b50SAl Viro 14169875cf80SDavid Howells /* 1417f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1418f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1419baa03890SNick Piggin */ 1420e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1421e3c13928SAl Viro struct dentry *dir, 14226c51e513SAl Viro unsigned int flags) 1423baa03890SNick Piggin { 1424a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1425bad61189SMiklos Szeredi if (dentry) { 1426a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1427bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 142874ff0ffcSAl Viro if (!error) 14295542aa2fSEric W. Biederman d_invalidate(dentry); 1430bad61189SMiklos Szeredi dput(dentry); 143174ff0ffcSAl Viro return ERR_PTR(error); 1432bad61189SMiklos Szeredi } 1433bad61189SMiklos Szeredi } 1434baa03890SNick Piggin return dentry; 1435baa03890SNick Piggin } 1436baa03890SNick Piggin 1437baa03890SNick Piggin /* 1438a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1439a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1440a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1441a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1442a03ece5fSAl Viro * at all. 144344396f4bSJosef Bacik */ 1444a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1445a03ece5fSAl Viro struct dentry *base, unsigned int flags) 144644396f4bSJosef Bacik { 1447a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 144844396f4bSJosef Bacik struct dentry *old; 1449a03ece5fSAl Viro struct inode *dir = base->d_inode; 1450a03ece5fSAl Viro 1451a03ece5fSAl Viro if (dentry) 1452a03ece5fSAl Viro return dentry; 145344396f4bSJosef Bacik 145444396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1455a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 145644396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1457a03ece5fSAl Viro 1458a03ece5fSAl Viro dentry = d_alloc(base, name); 1459a03ece5fSAl Viro if (unlikely(!dentry)) 1460a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 146144396f4bSJosef Bacik 146272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 146344396f4bSJosef Bacik if (unlikely(old)) { 146444396f4bSJosef Bacik dput(dentry); 146544396f4bSJosef Bacik dentry = old; 146644396f4bSJosef Bacik } 146744396f4bSJosef Bacik return dentry; 146844396f4bSJosef Bacik } 146944396f4bSJosef Bacik 147020e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 147120e34357SAl Viro struct inode **inode, 1472254cf582SAl Viro unsigned *seqp) 14731da177e4SLinus Torvalds { 147431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14755a18fff2SAl Viro int status = 1; 14769875cf80SDavid Howells 14773cac260aSAl Viro /* 1478b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 14795d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 14805d0f49c1SAl Viro * going to fall back to non-racy lookup. 1481b04f784eSNick Piggin */ 148231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 148331e6b01fSNick Piggin unsigned seq; 1484da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14855d0f49c1SAl Viro if (unlikely(!dentry)) { 14864675ac39SAl Viro if (unlazy_walk(nd)) 148720e34357SAl Viro return ERR_PTR(-ECHILD); 148820e34357SAl Viro return NULL; 14895d0f49c1SAl Viro } 14905a18fff2SAl Viro 149112f8ad4bSLinus Torvalds /* 149212f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 149312f8ad4bSLinus Torvalds * the dentry name information from lookup. 149412f8ad4bSLinus Torvalds */ 149563afdfc7SDavid Howells *inode = d_backing_inode(dentry); 14965d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 149720e34357SAl Viro return ERR_PTR(-ECHILD); 149812f8ad4bSLinus Torvalds 149912f8ad4bSLinus Torvalds /* 150012f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 150112f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 150212f8ad4bSLinus Torvalds * 150312f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 150412f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 150512f8ad4bSLinus Torvalds */ 15065d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 150720e34357SAl Viro return ERR_PTR(-ECHILD); 15085a18fff2SAl Viro 1509254cf582SAl Viro *seqp = seq; 15104ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1511c153007bSAl Viro if (likely(status > 0)) 151220e34357SAl Viro return dentry; 15134675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 151420e34357SAl Viro return ERR_PTR(-ECHILD); 1515209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1516209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1517209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15185a18fff2SAl Viro } else { 1519e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 152081e6f520SAl Viro if (unlikely(!dentry)) 152120e34357SAl Viro return NULL; 15224ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15235d0f49c1SAl Viro } 15245a18fff2SAl Viro if (unlikely(status <= 0)) { 1525e9742b53SAl Viro if (!status) 15265d0f49c1SAl Viro d_invalidate(dentry); 15275a18fff2SAl Viro dput(dentry); 152820e34357SAl Viro return ERR_PTR(status); 15295a18fff2SAl Viro } 153020e34357SAl Viro return dentry; 1531697f514dSMiklos Szeredi } 1532697f514dSMiklos Szeredi 1533697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 153488d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1535e3c13928SAl Viro struct dentry *dir, 1536e3c13928SAl Viro unsigned int flags) 1537697f514dSMiklos Szeredi { 153888d8331aSAl Viro struct dentry *dentry, *old; 15391936386eSAl Viro struct inode *inode = dir->d_inode; 1540d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15411936386eSAl Viro 15421936386eSAl Viro /* Don't go there if it's already dead */ 154394bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 154488d8331aSAl Viro return ERR_PTR(-ENOENT); 154594bdd655SAl Viro again: 1546d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 154794bdd655SAl Viro if (IS_ERR(dentry)) 154888d8331aSAl Viro return dentry; 154994bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1550949a852eSAl Viro int error = d_revalidate(dentry, flags); 1551949a852eSAl Viro if (unlikely(error <= 0)) { 155294bdd655SAl Viro if (!error) { 1553949a852eSAl Viro d_invalidate(dentry); 1554949a852eSAl Viro dput(dentry); 155594bdd655SAl Viro goto again; 155694bdd655SAl Viro } 155794bdd655SAl Viro dput(dentry); 1558949a852eSAl Viro dentry = ERR_PTR(error); 1559949a852eSAl Viro } 156094bdd655SAl Viro } else { 15611936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 156285c7f810SAl Viro d_lookup_done(dentry); 15631936386eSAl Viro if (unlikely(old)) { 15641936386eSAl Viro dput(dentry); 15651936386eSAl Viro dentry = old; 1566949a852eSAl Viro } 1567949a852eSAl Viro } 1568e3c13928SAl Viro return dentry; 15691da177e4SLinus Torvalds } 15701da177e4SLinus Torvalds 157188d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 157288d8331aSAl Viro struct dentry *dir, 157388d8331aSAl Viro unsigned int flags) 157488d8331aSAl Viro { 157588d8331aSAl Viro struct inode *inode = dir->d_inode; 157688d8331aSAl Viro struct dentry *res; 157788d8331aSAl Viro inode_lock_shared(inode); 157888d8331aSAl Viro res = __lookup_slow(name, dir, flags); 157988d8331aSAl Viro inode_unlock_shared(inode); 158088d8331aSAl Viro return res; 158188d8331aSAl Viro } 158288d8331aSAl Viro 158352094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 158452094c8aSAl Viro { 158552094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15864ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 158752094c8aSAl Viro if (err != -ECHILD) 158852094c8aSAl Viro return err; 15894675ac39SAl Viro if (unlazy_walk(nd)) 159052094c8aSAl Viro return -ECHILD; 159152094c8aSAl Viro } 15924ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 159352094c8aSAl Viro } 159452094c8aSAl Viro 1595b1a81972SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 1596b1a81972SAl Viro 159706708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1598b1a81972SAl Viro struct inode *inode, unsigned seq, int flags) 1599d63ff28fSAl Viro { 16001cf2665bSAl Viro struct saved *last; 1601ad6cc4c3SAl Viro const char *res; 1602ad6cc4c3SAl Viro int error; 1603ad6cc4c3SAl Viro 1604756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 160584f0cd9eSAl Viro if (!(nd->flags & LOOKUP_RCU)) 160684f0cd9eSAl Viro path_put(link); 160706708adbSAl Viro return ERR_PTR(-ELOOP); 1608626de996SAl Viro } 1609626de996SAl Viro error = nd_alloc_stack(nd); 1610626de996SAl Viro if (unlikely(error)) { 1611bc40aee0SAl Viro if (error == -ECHILD) { 1612ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1613ad1633a1SAl Viro drop_links(nd); 1614ad1633a1SAl Viro nd->depth = 0; 1615ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1616ad1633a1SAl Viro nd->path.mnt = NULL; 1617ad1633a1SAl Viro nd->path.dentry = NULL; 1618ad1633a1SAl Viro rcu_read_unlock(); 16194675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1620bc40aee0SAl Viro error = nd_alloc_stack(nd); 1621bc40aee0SAl Viro } 1622bc40aee0SAl Viro if (error) { 1623cd179f44SAl Viro path_put(link); 162406708adbSAl Viro return ERR_PTR(error); 1625626de996SAl Viro } 1626bc40aee0SAl Viro } 1627626de996SAl Viro 1628ab104923SAl Viro last = nd->stack + nd->depth++; 16291cf2665bSAl Viro last->link = *link; 1630fceef393SAl Viro clear_delayed_call(&last->done); 16310450b2d1SAl Viro last->seq = seq; 1632ad6cc4c3SAl Viro 1633b1a81972SAl Viro if (flags & WALK_TRAILING) { 1634ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1635ad6cc4c3SAl Viro if (unlikely(error)) 1636ad6cc4c3SAl Viro return ERR_PTR(error); 1637ad6cc4c3SAl Viro } 1638ad6cc4c3SAl Viro 1639ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1640ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1641ad6cc4c3SAl Viro 1642ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1643ad6cc4c3SAl Viro touch_atime(&last->link); 1644ad6cc4c3SAl Viro cond_resched(); 1645ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1646ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1647ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1648ad6cc4c3SAl Viro touch_atime(&last->link); 1649ad6cc4c3SAl Viro } 1650ad6cc4c3SAl Viro 1651ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1652ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1653ad6cc4c3SAl Viro if (unlikely(error)) 1654ad6cc4c3SAl Viro return ERR_PTR(error); 1655ad6cc4c3SAl Viro 1656ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1657ad6cc4c3SAl Viro if (!res) { 1658ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1659ad6cc4c3SAl Viro struct delayed_call *); 1660ad6cc4c3SAl Viro get = inode->i_op->get_link; 1661ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1662ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1663ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1664ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1665ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1666ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1667ad6cc4c3SAl Viro } 1668ad6cc4c3SAl Viro } else { 1669ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1670ad6cc4c3SAl Viro } 1671ad6cc4c3SAl Viro if (!res) 1672ad6cc4c3SAl Viro goto all_done; 1673ad6cc4c3SAl Viro if (IS_ERR(res)) 1674ad6cc4c3SAl Viro return res; 1675ad6cc4c3SAl Viro } 1676ad6cc4c3SAl Viro if (*res == '/') { 1677ad6cc4c3SAl Viro error = nd_jump_root(nd); 1678ad6cc4c3SAl Viro if (unlikely(error)) 1679ad6cc4c3SAl Viro return ERR_PTR(error); 1680ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1681ad6cc4c3SAl Viro ; 1682ad6cc4c3SAl Viro } 1683ad6cc4c3SAl Viro if (*res) 1684ad6cc4c3SAl Viro return res; 1685ad6cc4c3SAl Viro all_done: // pure jump 1686ad6cc4c3SAl Viro put_link(nd); 1687ad6cc4c3SAl Viro return NULL; 1688d63ff28fSAl Viro } 1689d63ff28fSAl Viro 16903ddcd056SLinus Torvalds /* 16913ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16923ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16933ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16943ddcd056SLinus Torvalds * for the common case. 16953ddcd056SLinus Torvalds */ 1696b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1697cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 16983ddcd056SLinus Torvalds { 1699cbae4d12SAl Viro struct path path; 1700cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1701cbae4d12SAl Viro 1702cbae4d12SAl Viro if (err < 0) 1703b0417d2cSAl Viro return ERR_PTR(err); 1704cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 17058c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1706aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 17078f64fb1cSAl Viro /* not a symlink or should not follow */ 1708cbae4d12SAl Viro path_to_nameidata(&path, nd); 17098f64fb1cSAl Viro nd->inode = inode; 17108f64fb1cSAl Viro nd->seq = seq; 1711b0417d2cSAl Viro return NULL; 17128f64fb1cSAl Viro } 1713a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 171484f0cd9eSAl Viro /* make sure that d_is_symlink above matches inode */ 1715cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1716b0417d2cSAl Viro return ERR_PTR(-ECHILD); 171784f0cd9eSAl Viro } else { 171884f0cd9eSAl Viro if (path.mnt == nd->path.mnt) 171984f0cd9eSAl Viro mntget(path.mnt); 1720a7f77542SAl Viro } 1721b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 17223ddcd056SLinus Torvalds } 17233ddcd056SLinus Torvalds 1724c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1725c2df1968SAl Viro struct inode **inodep, 1726c2df1968SAl Viro unsigned *seqp) 1727957dd41dSAl Viro { 172812487f30SAl Viro struct dentry *parent, *old; 1729957dd41dSAl Viro 173012487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 173112487f30SAl Viro goto in_root; 173212487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17337ef482faSAl Viro struct path path; 1734efe772d6SAl Viro unsigned seq; 17357ef482faSAl Viro if (!choose_mountpoint_rcu(real_mount(nd->path.mnt), 17367ef482faSAl Viro &nd->root, &path, &seq)) 173712487f30SAl Viro goto in_root; 1738efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1739efe772d6SAl Viro return ERR_PTR(-ECHILD); 1740efe772d6SAl Viro nd->path = path; 1741efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1742efe772d6SAl Viro nd->seq = seq; 1743efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1744efe772d6SAl Viro return ERR_PTR(-ECHILD); 1745efe772d6SAl Viro /* we know that mountpoint was pinned */ 1746957dd41dSAl Viro } 174712487f30SAl Viro old = nd->path.dentry; 174812487f30SAl Viro parent = old->d_parent; 174912487f30SAl Viro *inodep = parent->d_inode; 175012487f30SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 175112487f30SAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 175212487f30SAl Viro return ERR_PTR(-ECHILD); 175312487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 175412487f30SAl Viro return ERR_PTR(-ECHILD); 175512487f30SAl Viro return parent; 175612487f30SAl Viro in_root: 1757efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1758efe772d6SAl Viro return ERR_PTR(-ECHILD); 1759957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17607521f22bSAl Viro return ERR_PTR(-ECHILD); 1761c2df1968SAl Viro return NULL; 1762957dd41dSAl Viro } 1763957dd41dSAl Viro 1764c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1765c2df1968SAl Viro struct inode **inodep, 1766c2df1968SAl Viro unsigned *seqp) 1767957dd41dSAl Viro { 176812487f30SAl Viro struct dentry *parent; 176912487f30SAl Viro 1770957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 177112487f30SAl Viro goto in_root; 177212487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17732aa38470SAl Viro struct path path; 17742aa38470SAl Viro 17752aa38470SAl Viro if (!choose_mountpoint(real_mount(nd->path.mnt), 17762aa38470SAl Viro &nd->root, &path)) 177712487f30SAl Viro goto in_root; 1778165200d6SAl Viro path_put(&nd->path); 1779165200d6SAl Viro nd->path = path; 17802aa38470SAl Viro nd->inode = path.dentry->d_inode; 1781165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1782165200d6SAl Viro return ERR_PTR(-EXDEV); 178312487f30SAl Viro } 1784957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 178512487f30SAl Viro parent = dget_parent(nd->path.dentry); 1786957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1787957dd41dSAl Viro dput(parent); 17887521f22bSAl Viro return ERR_PTR(-ENOENT); 1789957dd41dSAl Viro } 1790c2df1968SAl Viro *seqp = 0; 1791c2df1968SAl Viro *inodep = parent->d_inode; 1792c2df1968SAl Viro return parent; 179312487f30SAl Viro 179412487f30SAl Viro in_root: 1795957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17967521f22bSAl Viro return ERR_PTR(-EXDEV); 1797c2df1968SAl Viro dget(nd->path.dentry); 1798c2df1968SAl Viro return NULL; 1799957dd41dSAl Viro } 1800957dd41dSAl Viro 18017521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1802957dd41dSAl Viro { 1803957dd41dSAl Viro if (type == LAST_DOTDOT) { 18047521f22bSAl Viro const char *error = NULL; 1805c2df1968SAl Viro struct dentry *parent; 1806c2df1968SAl Viro struct inode *inode; 1807c2df1968SAl Viro unsigned seq; 1808957dd41dSAl Viro 1809957dd41dSAl Viro if (!nd->root.mnt) { 18107521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1811957dd41dSAl Viro if (error) 1812957dd41dSAl Viro return error; 1813957dd41dSAl Viro } 1814957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1815c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1816957dd41dSAl Viro else 1817c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1818c2df1968SAl Viro if (IS_ERR(parent)) 1819c2df1968SAl Viro return ERR_CAST(parent); 1820c2df1968SAl Viro if (unlikely(!parent)) 1821c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1822c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1823c2df1968SAl Viro else 1824c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1825c2df1968SAl Viro parent, inode, seq); 1826c2df1968SAl Viro if (unlikely(error)) 1827957dd41dSAl Viro return error; 1828957dd41dSAl Viro 1829957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1830957dd41dSAl Viro /* 1831957dd41dSAl Viro * If there was a racing rename or mount along our 1832957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1833957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1834957dd41dSAl Viro * some fallback). 1835957dd41dSAl Viro */ 1836957dd41dSAl Viro smp_rmb(); 1837957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 18387521f22bSAl Viro return ERR_PTR(-EAGAIN); 1839957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 18407521f22bSAl Viro return ERR_PTR(-EAGAIN); 1841957dd41dSAl Viro } 1842957dd41dSAl Viro } 18437521f22bSAl Viro return NULL; 1844957dd41dSAl Viro } 1845957dd41dSAl Viro 184692d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1847ce57dfc1SAl Viro { 1848db3c9adeSAl Viro struct dentry *dentry; 1849ce57dfc1SAl Viro struct inode *inode; 1850254cf582SAl Viro unsigned seq; 1851ce57dfc1SAl Viro /* 1852ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1853ce57dfc1SAl Viro * to be able to know about the current root directory and 1854ce57dfc1SAl Viro * parent relationships. 1855ce57dfc1SAl Viro */ 18564693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18571c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18584693a547SAl Viro put_link(nd); 18597521f22bSAl Viro return handle_dots(nd, nd->last_type); 18604693a547SAl Viro } 186120e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 186220e34357SAl Viro if (IS_ERR(dentry)) 186392d27016SAl Viro return ERR_CAST(dentry); 186420e34357SAl Viro if (unlikely(!dentry)) { 1865db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1866db3c9adeSAl Viro if (IS_ERR(dentry)) 186792d27016SAl Viro return ERR_CAST(dentry); 186820e34357SAl Viro } 186956676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 187056676ec3SAl Viro put_link(nd); 1871b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1872ce57dfc1SAl Viro } 1873ce57dfc1SAl Viro 18741da177e4SLinus Torvalds /* 1875bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1876bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1877bfcfaa77SLinus Torvalds * 1878bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1879bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1880bfcfaa77SLinus Torvalds * fast. 1881bfcfaa77SLinus Torvalds * 1882bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1883bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1884bfcfaa77SLinus Torvalds * crossing operation. 1885bfcfaa77SLinus Torvalds * 1886bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1887bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1888bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1889bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1890bfcfaa77SLinus Torvalds */ 1891bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1892bfcfaa77SLinus Torvalds 1893f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1894bfcfaa77SLinus Torvalds 1895468a9428SGeorge Spelvin #ifdef HASH_MIX 1896bfcfaa77SLinus Torvalds 1897468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1898468a9428SGeorge Spelvin 1899468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 19002a18da7aSGeorge Spelvin /* 19012a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 19022a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 19032a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19042a18da7aSGeorge Spelvin * and no temporaries. 19052a18da7aSGeorge Spelvin * 19062a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19072a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19082a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19092a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19102a18da7aSGeorge Spelvin * 19112a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19122a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19132a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19142a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19152a18da7aSGeorge Spelvin * 19162a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19172a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19182a18da7aSGeorge Spelvin * toggling any given output bit. 19192a18da7aSGeorge Spelvin * 19202a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19212a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19222a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19232a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19242a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19252a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19262a18da7aSGeorge Spelvin * Perfect: 8192 258048 19272a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19282a18da7aSGeorge Spelvin */ 19292a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19302a18da7aSGeorge Spelvin ( x ^= (a), \ 19312a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19322a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19332a18da7aSGeorge Spelvin y *= 9 ) 1934bfcfaa77SLinus Torvalds 19350fed3ac8SGeorge Spelvin /* 19362a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19372a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19382a18da7aSGeorge Spelvin * work done before the hash value is used. 19390fed3ac8SGeorge Spelvin */ 19402a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19410fed3ac8SGeorge Spelvin { 19422a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19432a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19442a18da7aSGeorge Spelvin return y >> 32; 19450fed3ac8SGeorge Spelvin } 19460fed3ac8SGeorge Spelvin 1947bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1948bfcfaa77SLinus Torvalds 19492a18da7aSGeorge Spelvin /* 19502a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19512a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19522a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19532a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19542a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19552a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19562a18da7aSGeorge Spelvin * Perfect: 2048 31744 19572a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19582a18da7aSGeorge Spelvin */ 19592a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19602a18da7aSGeorge Spelvin ( x ^= (a), \ 19612a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19622a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19632a18da7aSGeorge Spelvin y *= 9 ) 1964bfcfaa77SLinus Torvalds 19652a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19660fed3ac8SGeorge Spelvin { 19672a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19682a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19690fed3ac8SGeorge Spelvin } 19700fed3ac8SGeorge Spelvin 1971bfcfaa77SLinus Torvalds #endif 1972bfcfaa77SLinus Torvalds 19732a18da7aSGeorge Spelvin /* 19742a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19752a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19762a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19772a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19782a18da7aSGeorge Spelvin * finds the delimiter after the name. 19792a18da7aSGeorge Spelvin */ 19808387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1981bfcfaa77SLinus Torvalds { 19828387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1983bfcfaa77SLinus Torvalds 1984bfcfaa77SLinus Torvalds for (;;) { 1985fcfd2fbfSGeorge Spelvin if (!len) 1986fcfd2fbfSGeorge Spelvin goto done; 1987e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1988bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1989bfcfaa77SLinus Torvalds break; 19902a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1991bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1992bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1993bfcfaa77SLinus Torvalds } 19942a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1995bfcfaa77SLinus Torvalds done: 19962a18da7aSGeorge Spelvin return fold_hash(x, y); 1997bfcfaa77SLinus Torvalds } 1998bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1999bfcfaa77SLinus Torvalds 2000fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20018387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2002fcfd2fbfSGeorge Spelvin { 20038387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20048387ff25SLinus Torvalds unsigned long adata, mask, len; 2005fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2006fcfd2fbfSGeorge Spelvin 20078387ff25SLinus Torvalds len = 0; 20088387ff25SLinus Torvalds goto inside; 20098387ff25SLinus Torvalds 2010fcfd2fbfSGeorge Spelvin do { 20112a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2012fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20138387ff25SLinus Torvalds inside: 2014fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2015fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2016fcfd2fbfSGeorge Spelvin 2017fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2018fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20192a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2020fcfd2fbfSGeorge Spelvin 20212a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2022fcfd2fbfSGeorge Spelvin } 2023fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2024fcfd2fbfSGeorge Spelvin 2025bfcfaa77SLinus Torvalds /* 2026bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2027d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2028bfcfaa77SLinus Torvalds */ 20298387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2030bfcfaa77SLinus Torvalds { 20318387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20328387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 203336126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2034bfcfaa77SLinus Torvalds 20358387ff25SLinus Torvalds len = 0; 20368387ff25SLinus Torvalds goto inside; 20378387ff25SLinus Torvalds 2038bfcfaa77SLinus Torvalds do { 20392a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2040bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20418387ff25SLinus Torvalds inside: 2042e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 204336126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 204436126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2045bfcfaa77SLinus Torvalds 204636126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 204736126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 204836126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20492a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 205036126f8fSLinus Torvalds 20512a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2052bfcfaa77SLinus Torvalds } 2053bfcfaa77SLinus Torvalds 20542a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2055bfcfaa77SLinus Torvalds 2056fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20578387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20580145acc2SLinus Torvalds { 20598387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20600145acc2SLinus Torvalds while (len--) 2061fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20620145acc2SLinus Torvalds return end_name_hash(hash); 20630145acc2SLinus Torvalds } 2064ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20650145acc2SLinus Torvalds 2066fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20678387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2068fcfd2fbfSGeorge Spelvin { 20698387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2070fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2071fcfd2fbfSGeorge Spelvin 2072fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2073e0ab7af9SGeorge Spelvin while (c) { 2074fcfd2fbfSGeorge Spelvin len++; 2075fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2076fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2077e0ab7af9SGeorge Spelvin } 2078fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2079fcfd2fbfSGeorge Spelvin } 2080f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2081fcfd2fbfSGeorge Spelvin 20823ddcd056SLinus Torvalds /* 2083200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2084200e9ef7SLinus Torvalds * one character. 2085200e9ef7SLinus Torvalds */ 20868387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2087200e9ef7SLinus Torvalds { 20888387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2089200e9ef7SLinus Torvalds unsigned long len = 0, c; 2090200e9ef7SLinus Torvalds 2091200e9ef7SLinus Torvalds c = (unsigned char)*name; 2092200e9ef7SLinus Torvalds do { 2093200e9ef7SLinus Torvalds len++; 2094200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2095200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2096200e9ef7SLinus Torvalds } while (c && c != '/'); 2097d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2098200e9ef7SLinus Torvalds } 2099200e9ef7SLinus Torvalds 2100bfcfaa77SLinus Torvalds #endif 2101bfcfaa77SLinus Torvalds 2102200e9ef7SLinus Torvalds /* 21031da177e4SLinus Torvalds * Name resolution. 2104ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2105ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21061da177e4SLinus Torvalds * 2107ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2108ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21091da177e4SLinus Torvalds */ 21106de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21111da177e4SLinus Torvalds { 2112d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 21131da177e4SLinus Torvalds int err; 21141da177e4SLinus Torvalds 2115b4c03536SAl Viro nd->last_type = LAST_ROOT; 2116c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 21179b5858e9SAl Viro if (IS_ERR(name)) 21189b5858e9SAl Viro return PTR_ERR(name); 21191da177e4SLinus Torvalds while (*name=='/') 21201da177e4SLinus Torvalds name++; 21211da177e4SLinus Torvalds if (!*name) 21229e18f10aSAl Viro return 0; 21231da177e4SLinus Torvalds 21241da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21251da177e4SLinus Torvalds for(;;) { 212692d27016SAl Viro const char *link; 2127d6bb3e90SLinus Torvalds u64 hash_len; 2128fe479a58SAl Viro int type; 21291da177e4SLinus Torvalds 213052094c8aSAl Viro err = may_lookup(nd); 21311da177e4SLinus Torvalds if (err) 21323595e234SAl Viro return err; 21331da177e4SLinus Torvalds 21348387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21351da177e4SLinus Torvalds 2136fe479a58SAl Viro type = LAST_NORM; 2137d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2138fe479a58SAl Viro case 2: 2139200e9ef7SLinus Torvalds if (name[1] == '.') { 2140fe479a58SAl Viro type = LAST_DOTDOT; 214116c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 214216c2cd71SAl Viro } 2143fe479a58SAl Viro break; 2144fe479a58SAl Viro case 1: 2145fe479a58SAl Viro type = LAST_DOT; 2146fe479a58SAl Viro } 21475a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21485a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 214916c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21505a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2151a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2152da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21535a202bcdSAl Viro if (err < 0) 21543595e234SAl Viro return err; 2155d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2156d6bb3e90SLinus Torvalds name = this.name; 21575a202bcdSAl Viro } 21585a202bcdSAl Viro } 2159fe479a58SAl Viro 2160d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2161d6bb3e90SLinus Torvalds nd->last.name = name; 21625f4a6a69SAl Viro nd->last_type = type; 21635f4a6a69SAl Viro 2164d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2165d6bb3e90SLinus Torvalds if (!*name) 2166bdf6cbf1SAl Viro goto OK; 2167200e9ef7SLinus Torvalds /* 2168200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2169200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2170200e9ef7SLinus Torvalds */ 2171200e9ef7SLinus Torvalds do { 2172d6bb3e90SLinus Torvalds name++; 2173d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21748620c238SAl Viro if (unlikely(!*name)) { 21758620c238SAl Viro OK: 2176d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2177c108837eSAl Viro if (!depth) { 2178c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 21798620c238SAl Viro return 0; 2180c108837eSAl Viro } 21818620c238SAl Viro /* last component of nested symlink */ 2182d8d4611aSAl Viro name = nd->stack[--depth].name; 21838c4efe22SAl Viro link = walk_component(nd, 0); 21841c4ff1a8SAl Viro } else { 21851c4ff1a8SAl Viro /* not the last component */ 21868c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 21878620c238SAl Viro } 218892d27016SAl Viro if (unlikely(link)) { 218992d27016SAl Viro if (IS_ERR(link)) 219092d27016SAl Viro return PTR_ERR(link); 219192d27016SAl Viro /* a symlink to follow */ 2192d8d4611aSAl Viro nd->stack[depth++].name = name; 219392d27016SAl Viro name = link; 21949e18f10aSAl Viro continue; 219548c8b0c5SAl Viro } 219697242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 219797242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21984675ac39SAl Viro if (unlazy_walk(nd)) 219997242f99SAl Viro return -ECHILD; 220097242f99SAl Viro } 22013595e234SAl Viro return -ENOTDIR; 22025f4a6a69SAl Viro } 2203ce57dfc1SAl Viro } 220497242f99SAl Viro } 22051da177e4SLinus Torvalds 2206edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2207c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 220831e6b01fSNick Piggin { 2209740a1678SAleksa Sarai int error; 2210c8a53ee5SAl Viro const char *s = nd->name->name; 221131e6b01fSNick Piggin 2212c0eb027eSLinus Torvalds if (!*s) 2213c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2214edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2215edc2b1daSAl Viro rcu_read_lock(); 2216c0eb027eSLinus Torvalds 2217c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 221831e6b01fSNick Piggin nd->depth = 0; 2219ab87f9a5SAleksa Sarai 2220ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2221ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2222ab87f9a5SAleksa Sarai smp_rmb(); 2223ab87f9a5SAleksa Sarai 22245b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2225b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2226b18825a7SDavid Howells struct inode *inode = root->d_inode; 222793893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2228368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22295b6ca027SAl Viro nd->path = nd->root; 22305b6ca027SAl Viro nd->inode = inode; 22315b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2232ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22338f47a016SAl Viro nd->root_seq = nd->seq; 22345b6ca027SAl Viro } else { 22355b6ca027SAl Viro path_get(&nd->path); 22365b6ca027SAl Viro } 2237368ee9baSAl Viro return s; 22385b6ca027SAl Viro } 22395b6ca027SAl Viro 224031e6b01fSNick Piggin nd->root.mnt = NULL; 2241248fb5b9SAl Viro nd->path.mnt = NULL; 2242248fb5b9SAl Viro nd->path.dentry = NULL; 224331e6b01fSNick Piggin 22448db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22458db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2246740a1678SAleksa Sarai error = nd_jump_root(nd); 2247740a1678SAleksa Sarai if (unlikely(error)) 2248740a1678SAleksa Sarai return ERR_PTR(error); 2249ef55d917SAl Viro return s; 22508db52c7eSAleksa Sarai } 22518db52c7eSAleksa Sarai 22528db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22538db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2254e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 225531e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2256c28cc364SNick Piggin unsigned seq; 225731e6b01fSNick Piggin 2258c28cc364SNick Piggin do { 2259c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 226031e6b01fSNick Piggin nd->path = fs->pwd; 2261ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2262c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2263c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2264e41f7d4eSAl Viro } else { 2265e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2266ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2267e41f7d4eSAl Viro } 226831e6b01fSNick Piggin } else { 2269582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2270c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 227131e6b01fSNick Piggin struct dentry *dentry; 227231e6b01fSNick Piggin 22732903ff01SAl Viro if (!f.file) 2274368ee9baSAl Viro return ERR_PTR(-EBADF); 227531e6b01fSNick Piggin 22762903ff01SAl Viro dentry = f.file->f_path.dentry; 227731e6b01fSNick Piggin 2278edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22792903ff01SAl Viro fdput(f); 2280368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2281f52e0c11SAl Viro } 22822903ff01SAl Viro 22832903ff01SAl Viro nd->path = f.file->f_path; 2284e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 228534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 228634a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22875590ff0dSUlrich Drepper } else { 22882903ff01SAl Viro path_get(&nd->path); 228934a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22901da177e4SLinus Torvalds } 229134a26b99SAl Viro fdput(f); 2292e41f7d4eSAl Viro } 22938db52c7eSAleksa Sarai 2294adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2295adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2296adb21d2bSAleksa Sarai nd->root = nd->path; 2297adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2298adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2299adb21d2bSAleksa Sarai } else { 2300adb21d2bSAleksa Sarai path_get(&nd->root); 2301adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2302adb21d2bSAleksa Sarai } 2303adb21d2bSAleksa Sarai } 2304adb21d2bSAleksa Sarai return s; 23059b4a9b14SAl Viro } 23069b4a9b14SAl Viro 23071ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 230895fa25d9SAl Viro { 2309bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2310bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2311bd92d7feSAl Viro 2312c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2313bd92d7feSAl Viro } 2314bd92d7feSAl Viro 23154f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23164f757f3cSAl Viro { 2317c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2318db3c9adeSAl Viro dget(nd->path.dentry); 2319b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2320b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23214f757f3cSAl Viro } 23224f757f3cSAl Viro 23239b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2324c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23259b4a9b14SAl Viro { 2326c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2327bd92d7feSAl Viro int err; 232831e6b01fSNick Piggin 23299b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23304f757f3cSAl Viro err = handle_lookup_down(nd); 23315f336e72SAl Viro if (unlikely(err < 0)) 23325f336e72SAl Viro s = ERR_PTR(err); 23334f757f3cSAl Viro } 23344f757f3cSAl Viro 23351ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23361ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23371ccac622SAl Viro ; 23389f1fafeeSAl Viro if (!err) 23399f1fafeeSAl Viro err = complete_walk(nd); 2340bd92d7feSAl Viro 2341deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2342deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2343bd23a539SAl Viro err = -ENOTDIR; 2344161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2345161aff1dSAl Viro err = handle_lookup_down(nd); 2346161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2347161aff1dSAl Viro } 2348625b6d10SAl Viro if (!err) { 2349625b6d10SAl Viro *path = nd->path; 2350625b6d10SAl Viro nd->path.mnt = NULL; 2351625b6d10SAl Viro nd->path.dentry = NULL; 2352625b6d10SAl Viro } 2353deb106c6SAl Viro terminate_walk(nd); 2354bd92d7feSAl Viro return err; 235531e6b01fSNick Piggin } 235631e6b01fSNick Piggin 235731d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23589ad1aaa6SAl Viro struct path *path, struct path *root) 2359873f1eedSJeff Layton { 2360894bc8c4SAl Viro int retval; 23619883d185SAl Viro struct nameidata nd; 2362abc9f5beSAl Viro if (IS_ERR(name)) 2363abc9f5beSAl Viro return PTR_ERR(name); 23649ad1aaa6SAl Viro if (unlikely(root)) { 23659ad1aaa6SAl Viro nd.root = *root; 23669ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23679ad1aaa6SAl Viro } 23689883d185SAl Viro set_nameidata(&nd, dfd, name); 2369c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2370873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2371c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2372873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2373c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2374873f1eedSJeff Layton 2375873f1eedSJeff Layton if (likely(!retval)) 2376161aff1dSAl Viro audit_inode(name, path->dentry, 2377161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23789883d185SAl Viro restore_nameidata(); 2379e4bd1c1aSAl Viro putname(name); 2380873f1eedSJeff Layton return retval; 2381873f1eedSJeff Layton } 2382873f1eedSJeff Layton 23838bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2384c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2385391172c4SAl Viro struct path *parent) 23868bcb77faSAl Viro { 2387c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23889b5858e9SAl Viro int err = link_path_walk(s, nd); 23898bcb77faSAl Viro if (!err) 23908bcb77faSAl Viro err = complete_walk(nd); 2391391172c4SAl Viro if (!err) { 2392391172c4SAl Viro *parent = nd->path; 2393391172c4SAl Viro nd->path.mnt = NULL; 2394391172c4SAl Viro nd->path.dentry = NULL; 2395391172c4SAl Viro } 2396deb106c6SAl Viro terminate_walk(nd); 23978bcb77faSAl Viro return err; 23988bcb77faSAl Viro } 23998bcb77faSAl Viro 24005c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2401391172c4SAl Viro unsigned int flags, struct path *parent, 2402391172c4SAl Viro struct qstr *last, int *type) 24038bcb77faSAl Viro { 24048bcb77faSAl Viro int retval; 24059883d185SAl Viro struct nameidata nd; 24068bcb77faSAl Viro 24075c31b6ceSAl Viro if (IS_ERR(name)) 24085c31b6ceSAl Viro return name; 24099883d185SAl Viro set_nameidata(&nd, dfd, name); 2410c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24118bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2412c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24138bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2414c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2415391172c4SAl Viro if (likely(!retval)) { 2416391172c4SAl Viro *last = nd.last; 2417391172c4SAl Viro *type = nd.last_type; 2418c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24195c31b6ceSAl Viro } else { 24205c31b6ceSAl Viro putname(name); 24215c31b6ceSAl Viro name = ERR_PTR(retval); 2422391172c4SAl Viro } 24239883d185SAl Viro restore_nameidata(); 24245c31b6ceSAl Viro return name; 24258bcb77faSAl Viro } 24268bcb77faSAl Viro 242779714f72SAl Viro /* does lookup, returns the object with parent locked */ 242879714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24295590ff0dSUlrich Drepper { 24305c31b6ceSAl Viro struct filename *filename; 24315c31b6ceSAl Viro struct dentry *d; 2432391172c4SAl Viro struct qstr last; 2433391172c4SAl Viro int type; 243451689104SPaul Moore 24355c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24365c31b6ceSAl Viro &last, &type); 243751689104SPaul Moore if (IS_ERR(filename)) 243851689104SPaul Moore return ERR_CAST(filename); 24395c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2440391172c4SAl Viro path_put(path); 24415c31b6ceSAl Viro putname(filename); 24425c31b6ceSAl Viro return ERR_PTR(-EINVAL); 244379714f72SAl Viro } 24445955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2445391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 244679714f72SAl Viro if (IS_ERR(d)) { 24475955102cSAl Viro inode_unlock(path->dentry->d_inode); 2448391172c4SAl Viro path_put(path); 244979714f72SAl Viro } 245051689104SPaul Moore putname(filename); 245179714f72SAl Viro return d; 24525590ff0dSUlrich Drepper } 24535590ff0dSUlrich Drepper 2454d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2455d1811465SAl Viro { 2456abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2457abc9f5beSAl Viro flags, path, NULL); 2458d1811465SAl Viro } 24594d359507SAl Viro EXPORT_SYMBOL(kern_path); 2460d1811465SAl Viro 246116f18200SJosef 'Jeff' Sipek /** 246216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 246316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 246416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 246516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 246616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2467e0a01249SAl Viro * @path: pointer to struct path to fill 246816f18200SJosef 'Jeff' Sipek */ 246916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 247016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2471e0a01249SAl Viro struct path *path) 247216f18200SJosef 'Jeff' Sipek { 24739ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24749ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2475abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2476abc9f5beSAl Viro flags , path, &root); 247716f18200SJosef 'Jeff' Sipek } 24784d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 247916f18200SJosef 'Jeff' Sipek 24803c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24813c95f0dcSAl Viro int len, struct qstr *this) 24823c95f0dcSAl Viro { 24833c95f0dcSAl Viro this->name = name; 24843c95f0dcSAl Viro this->len = len; 24853c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24863c95f0dcSAl Viro if (!len) 24873c95f0dcSAl Viro return -EACCES; 24883c95f0dcSAl Viro 24893c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24903c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24913c95f0dcSAl Viro return -EACCES; 24923c95f0dcSAl Viro } 24933c95f0dcSAl Viro 24943c95f0dcSAl Viro while (len--) { 24953c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24963c95f0dcSAl Viro if (c == '/' || c == '\0') 24973c95f0dcSAl Viro return -EACCES; 24983c95f0dcSAl Viro } 24993c95f0dcSAl Viro /* 25003c95f0dcSAl Viro * See if the low-level filesystem might want 25013c95f0dcSAl Viro * to use its own hash.. 25023c95f0dcSAl Viro */ 25033c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25043c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25053c95f0dcSAl Viro if (err < 0) 25063c95f0dcSAl Viro return err; 25073c95f0dcSAl Viro } 25083c95f0dcSAl Viro 25093c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 25103c95f0dcSAl Viro } 25113c95f0dcSAl Viro 2512eead1911SChristoph Hellwig /** 25130da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25140da0b7fdSDavid Howells * @name: pathname component to lookup 25150da0b7fdSDavid Howells * @base: base directory to lookup from 25160da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25170da0b7fdSDavid Howells * 25180da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25190da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25200da0b7fdSDavid Howells * 25210da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25220da0b7fdSDavid Howells * not be called by generic code. 25230da0b7fdSDavid Howells * 25240da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25250da0b7fdSDavid Howells */ 25260da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25270da0b7fdSDavid Howells { 25280da0b7fdSDavid Howells struct qstr this; 25290da0b7fdSDavid Howells int err; 25300da0b7fdSDavid Howells 25310da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25320da0b7fdSDavid Howells 25330da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25340da0b7fdSDavid Howells if (err) 25350da0b7fdSDavid Howells return ERR_PTR(err); 25360da0b7fdSDavid Howells 25370da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25380da0b7fdSDavid Howells } 25390da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25400da0b7fdSDavid Howells 25410da0b7fdSDavid Howells /** 2542a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2543eead1911SChristoph Hellwig * @name: pathname component to lookup 2544eead1911SChristoph Hellwig * @base: base directory to lookup from 2545eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2546eead1911SChristoph Hellwig * 2547a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25489e7543e9SAl Viro * not be called by generic code. 2549bbddca8eSNeilBrown * 2550bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2551eead1911SChristoph Hellwig */ 2552057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2553057f6c01SJames Morris { 25548613a209SAl Viro struct dentry *dentry; 2555057f6c01SJames Morris struct qstr this; 2556cda309deSMiklos Szeredi int err; 2557057f6c01SJames Morris 25585955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25592f9092e1SDavid Woodhouse 25603c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2561cda309deSMiklos Szeredi if (err) 2562cda309deSMiklos Szeredi return ERR_PTR(err); 2563cda309deSMiklos Szeredi 25648613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25658613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2566057f6c01SJames Morris } 25674d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2568057f6c01SJames Morris 2569bbddca8eSNeilBrown /** 2570bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2571bbddca8eSNeilBrown * @name: pathname component to lookup 2572bbddca8eSNeilBrown * @base: base directory to lookup from 2573bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2574bbddca8eSNeilBrown * 2575bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2576bbddca8eSNeilBrown * not be called by generic code. 2577bbddca8eSNeilBrown * 2578bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2579bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2580bbddca8eSNeilBrown */ 2581bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2582bbddca8eSNeilBrown struct dentry *base, int len) 2583bbddca8eSNeilBrown { 2584bbddca8eSNeilBrown struct qstr this; 2585bbddca8eSNeilBrown int err; 258620d00ee8SLinus Torvalds struct dentry *ret; 2587bbddca8eSNeilBrown 25883c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2589bbddca8eSNeilBrown if (err) 2590bbddca8eSNeilBrown return ERR_PTR(err); 2591bbddca8eSNeilBrown 259220d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 259320d00ee8SLinus Torvalds if (!ret) 259420d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 259520d00ee8SLinus Torvalds return ret; 2596bbddca8eSNeilBrown } 2597bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2598bbddca8eSNeilBrown 25996c2d4798SAl Viro /* 26006c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 26016c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 26026c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 26036c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26046c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26056c2d4798SAl Viro * this one avoids such problems. 26066c2d4798SAl Viro */ 26076c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26086c2d4798SAl Viro struct dentry *base, int len) 26096c2d4798SAl Viro { 26106c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26112fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26126c2d4798SAl Viro dput(ret); 26136c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26146c2d4798SAl Viro } 26156c2d4798SAl Viro return ret; 26166c2d4798SAl Viro } 26176c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26186c2d4798SAl Viro 2619eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2620eedf265aSEric W. Biederman int path_pts(struct path *path) 2621eedf265aSEric W. Biederman { 2622eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2623eedf265aSEric W. Biederman * the input path. 2624eedf265aSEric W. Biederman */ 2625a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2626a6a7eb76SAl Viro struct dentry *child; 262719f6028aSAl Viro struct qstr this = QSTR_INIT("pts", 3); 2628eedf265aSEric W. Biederman 2629a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2630a6a7eb76SAl Viro dput(parent); 263163b27720SAl Viro return -ENOENT; 2632a6a7eb76SAl Viro } 263363b27720SAl Viro dput(path->dentry); 263463b27720SAl Viro path->dentry = parent; 2635eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2636eedf265aSEric W. Biederman if (!child) 2637eedf265aSEric W. Biederman return -ENOENT; 2638eedf265aSEric W. Biederman 2639eedf265aSEric W. Biederman path->dentry = child; 2640eedf265aSEric W. Biederman dput(parent); 264119f6028aSAl Viro follow_down(path); 2642eedf265aSEric W. Biederman return 0; 2643eedf265aSEric W. Biederman } 2644eedf265aSEric W. Biederman #endif 2645eedf265aSEric W. Biederman 26461fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26471fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26481da177e4SLinus Torvalds { 2649abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2650abc9f5beSAl Viro flags, path, NULL); 26511da177e4SLinus Torvalds } 2652b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26531fa1e7f6SAndy Whitcroft 2654cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26551da177e4SLinus Torvalds { 26568e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2657da9592edSDavid Howells 26588e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26591da177e4SLinus Torvalds return 0; 26608e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26611da177e4SLinus Torvalds return 0; 266223adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26631da177e4SLinus Torvalds } 2664cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26651da177e4SLinus Torvalds 26661da177e4SLinus Torvalds /* 26671da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26681da177e4SLinus Torvalds * whether the type of victim is right. 26691da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26701da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26711da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26721da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26731da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26741da177e4SLinus Torvalds * a. be owner of dir, or 26751da177e4SLinus Torvalds * b. be owner of victim, or 26761da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26771da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26781da177e4SLinus Torvalds * links pointing to it. 26790bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26800bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26810bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26820bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 26830bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 26841da177e4SLinus Torvalds * nfs_async_unlink(). 26851da177e4SLinus Torvalds */ 2686b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26871da177e4SLinus Torvalds { 268863afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26891da177e4SLinus Torvalds int error; 26901da177e4SLinus Torvalds 2691b18825a7SDavid Howells if (d_is_negative(victim)) 26921da177e4SLinus Torvalds return -ENOENT; 2693b18825a7SDavid Howells BUG_ON(!inode); 26941da177e4SLinus Torvalds 26951da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2696593d1ce8SEric W. Biederman 2697593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2698593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2699593d1ce8SEric W. Biederman return -EOVERFLOW; 2700593d1ce8SEric W. Biederman 27014fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27021da177e4SLinus Torvalds 2703f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27041da177e4SLinus Torvalds if (error) 27051da177e4SLinus Torvalds return error; 27061da177e4SLinus Torvalds if (IS_APPEND(dir)) 27071da177e4SLinus Torvalds return -EPERM; 2708b18825a7SDavid Howells 2709b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27100bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27111da177e4SLinus Torvalds return -EPERM; 27121da177e4SLinus Torvalds if (isdir) { 271344b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27141da177e4SLinus Torvalds return -ENOTDIR; 27151da177e4SLinus Torvalds if (IS_ROOT(victim)) 27161da177e4SLinus Torvalds return -EBUSY; 271744b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27181da177e4SLinus Torvalds return -EISDIR; 27191da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27201da177e4SLinus Torvalds return -ENOENT; 27211da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27221da177e4SLinus Torvalds return -EBUSY; 27231da177e4SLinus Torvalds return 0; 27241da177e4SLinus Torvalds } 27251da177e4SLinus Torvalds 27261da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27271da177e4SLinus Torvalds * dir. 27281da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27291da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27301da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2731036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2732036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2733036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27341da177e4SLinus Torvalds */ 2735a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27361da177e4SLinus Torvalds { 2737036d5236SEric W. Biederman struct user_namespace *s_user_ns; 273814e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27391da177e4SLinus Torvalds if (child->d_inode) 27401da177e4SLinus Torvalds return -EEXIST; 27411da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27421da177e4SLinus Torvalds return -ENOENT; 2743036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2744036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2745036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2746036d5236SEric W. Biederman return -EOVERFLOW; 2747f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27481da177e4SLinus Torvalds } 27491da177e4SLinus Torvalds 27501da177e4SLinus Torvalds /* 27511da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27521da177e4SLinus Torvalds */ 27531da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27541da177e4SLinus Torvalds { 27551da177e4SLinus Torvalds struct dentry *p; 27561da177e4SLinus Torvalds 27571da177e4SLinus Torvalds if (p1 == p2) { 27585955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27591da177e4SLinus Torvalds return NULL; 27601da177e4SLinus Torvalds } 27611da177e4SLinus Torvalds 2762fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27631da177e4SLinus Torvalds 2764e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2765e2761a11SOGAWA Hirofumi if (p) { 27665955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27675955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27681da177e4SLinus Torvalds return p; 27691da177e4SLinus Torvalds } 27701da177e4SLinus Torvalds 2771e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2772e2761a11SOGAWA Hirofumi if (p) { 27735955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27745955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27751da177e4SLinus Torvalds return p; 27761da177e4SLinus Torvalds } 27771da177e4SLinus Torvalds 27785955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27795955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27801da177e4SLinus Torvalds return NULL; 27811da177e4SLinus Torvalds } 27824d359507SAl Viro EXPORT_SYMBOL(lock_rename); 27831da177e4SLinus Torvalds 27841da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 27851da177e4SLinus Torvalds { 27865955102cSAl Viro inode_unlock(p1->d_inode); 27871da177e4SLinus Torvalds if (p1 != p2) { 27885955102cSAl Viro inode_unlock(p2->d_inode); 2789fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 27901da177e4SLinus Torvalds } 27911da177e4SLinus Torvalds } 27924d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 27931da177e4SLinus Torvalds 27944acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2795312b63fbSAl Viro bool want_excl) 27961da177e4SLinus Torvalds { 2797a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27981da177e4SLinus Torvalds if (error) 27991da177e4SLinus Torvalds return error; 28001da177e4SLinus Torvalds 2801acfa4380SAl Viro if (!dir->i_op->create) 28021da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28031da177e4SLinus Torvalds mode &= S_IALLUGO; 28041da177e4SLinus Torvalds mode |= S_IFREG; 28051da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28061da177e4SLinus Torvalds if (error) 28071da177e4SLinus Torvalds return error; 2808312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2809a74574aaSStephen Smalley if (!error) 2810f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28111da177e4SLinus Torvalds return error; 28121da177e4SLinus Torvalds } 28134d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28141da177e4SLinus Torvalds 28158e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28168e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28178e6c848eSAl Viro void *arg) 28188e6c848eSAl Viro { 28198e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28208e6c848eSAl Viro int error = may_create(dir, dentry); 28218e6c848eSAl Viro if (error) 28228e6c848eSAl Viro return error; 28238e6c848eSAl Viro 28248e6c848eSAl Viro mode &= S_IALLUGO; 28258e6c848eSAl Viro mode |= S_IFREG; 28268e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28278e6c848eSAl Viro if (error) 28288e6c848eSAl Viro return error; 28298e6c848eSAl Viro error = f(dentry, mode, arg); 28308e6c848eSAl Viro if (!error) 28318e6c848eSAl Viro fsnotify_create(dir, dentry); 28328e6c848eSAl Viro return error; 28338e6c848eSAl Viro } 28348e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28358e6c848eSAl Viro 2836a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2837a2982cc9SEric W. Biederman { 2838a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2839a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2840a2982cc9SEric W. Biederman } 2841a2982cc9SEric W. Biederman 2842f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28431da177e4SLinus Torvalds { 28443fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28451da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28461da177e4SLinus Torvalds int error; 28471da177e4SLinus Torvalds 28481da177e4SLinus Torvalds if (!inode) 28491da177e4SLinus Torvalds return -ENOENT; 28501da177e4SLinus Torvalds 2851c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2852c8fe8f30SChristoph Hellwig case S_IFLNK: 28531da177e4SLinus Torvalds return -ELOOP; 2854c8fe8f30SChristoph Hellwig case S_IFDIR: 2855c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28561da177e4SLinus Torvalds return -EISDIR; 2857c8fe8f30SChristoph Hellwig break; 2858c8fe8f30SChristoph Hellwig case S_IFBLK: 2859c8fe8f30SChristoph Hellwig case S_IFCHR: 2860a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28611da177e4SLinus Torvalds return -EACCES; 2862c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2863c8fe8f30SChristoph Hellwig case S_IFIFO: 2864c8fe8f30SChristoph Hellwig case S_IFSOCK: 28651da177e4SLinus Torvalds flag &= ~O_TRUNC; 2866c8fe8f30SChristoph Hellwig break; 28674a3fd211SDave Hansen } 2868b41572e9SDave Hansen 286962fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2870b41572e9SDave Hansen if (error) 2871b41572e9SDave Hansen return error; 28726146f0d5SMimi Zohar 28731da177e4SLinus Torvalds /* 28741da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28751da177e4SLinus Torvalds */ 28761da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28778737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28787715b521SAl Viro return -EPERM; 28791da177e4SLinus Torvalds if (flag & O_TRUNC) 28807715b521SAl Viro return -EPERM; 28811da177e4SLinus Torvalds } 28821da177e4SLinus Torvalds 28831da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28842e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28857715b521SAl Viro return -EPERM; 28861da177e4SLinus Torvalds 2887f3c7691eSJ. Bruce Fields return 0; 28887715b521SAl Viro } 28897715b521SAl Viro 2890e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28917715b521SAl Viro { 2892f0bb5aafSAl Viro const struct path *path = &filp->f_path; 28937715b521SAl Viro struct inode *inode = path->dentry->d_inode; 28947715b521SAl Viro int error = get_write_access(inode); 28951da177e4SLinus Torvalds if (error) 28967715b521SAl Viro return error; 28971da177e4SLinus Torvalds /* 28981da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 28991da177e4SLinus Torvalds */ 2900d7a06983SJeff Layton error = locks_verify_locked(filp); 2901be6d3e56SKentaro Takeda if (!error) 2902ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29031da177e4SLinus Torvalds if (!error) { 29047715b521SAl Viro error = do_truncate(path->dentry, 0, 2905d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2906e1181ee6SJeff Layton filp); 29071da177e4SLinus Torvalds } 29081da177e4SLinus Torvalds put_write_access(inode); 2909acd0c935SMimi Zohar return error; 29101da177e4SLinus Torvalds } 29111da177e4SLinus Torvalds 2912d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2913d57999e1SDave Hansen { 29148a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29158a5e929dSAl Viro flag--; 2916d57999e1SDave Hansen return flag; 2917d57999e1SDave Hansen } 2918d57999e1SDave Hansen 2919d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2920d18e9008SMiklos Szeredi { 29211328c727SSeth Forshee struct user_namespace *s_user_ns; 2922d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2923d18e9008SMiklos Szeredi if (error) 2924d18e9008SMiklos Szeredi return error; 2925d18e9008SMiklos Szeredi 29261328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29271328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29281328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29291328c727SSeth Forshee return -EOVERFLOW; 29301328c727SSeth Forshee 2931d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2932d18e9008SMiklos Szeredi if (error) 2933d18e9008SMiklos Szeredi return error; 2934d18e9008SMiklos Szeredi 2935d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2936d18e9008SMiklos Szeredi } 2937d18e9008SMiklos Szeredi 29381acf0af9SDavid Howells /* 29391acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29401acf0af9SDavid Howells * dentry. 29411acf0af9SDavid Howells * 29421acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29431acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29441acf0af9SDavid Howells * 294500a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 294600a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 294700a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29481acf0af9SDavid Howells * 29491acf0af9SDavid Howells * Returns an error code otherwise. 29501acf0af9SDavid Howells */ 2951239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2952239eb983SAl Viro struct file *file, 2953015c3bbcSMiklos Szeredi const struct open_flags *op, 29543ec2eef1SAl Viro int open_flag, umode_t mode) 2955d18e9008SMiklos Szeredi { 2956d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2957d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2958d18e9008SMiklos Szeredi int error; 2959d18e9008SMiklos Szeredi 2960384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2961d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2962d18e9008SMiklos Szeredi 2963d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2964d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2965d18e9008SMiklos Szeredi 296630d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 296730d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29680fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 296944907d79SAl Viro open_to_namei_flags(open_flag), mode); 29706fbd0714SAl Viro d_lookup_done(dentry); 2971384f26e2SAl Viro if (!error) { 297264e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 29736fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 29746fb968cdSAl Viro dput(dentry); 29756fb968cdSAl Viro dentry = dget(file->f_path.dentry); 29766fb968cdSAl Viro } 29777be219b4SAl Viro if (file->f_mode & FMODE_CREATED) 297803da633aSAl Viro fsnotify_create(dir, dentry); 297964e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2980116cc022SMiklos Szeredi error = -EIO; 2981384f26e2SAl Viro } else { 2982d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2983d18e9008SMiklos Szeredi dput(dentry); 2984d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 298510c64ceaSAl Viro } 298673a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 2987d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2988239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 2989a01e718fSAl Viro error = -ENOENT; 2990d18e9008SMiklos Szeredi } 2991d18e9008SMiklos Szeredi } 2992239eb983SAl Viro if (error) { 2993d18e9008SMiklos Szeredi dput(dentry); 2994239eb983SAl Viro dentry = ERR_PTR(error); 2995239eb983SAl Viro } 2996239eb983SAl Viro return dentry; 2997d18e9008SMiklos Szeredi } 2998d18e9008SMiklos Szeredi 299931e6b01fSNick Piggin /* 30001acf0af9SDavid Howells * Look up and maybe create and open the last component. 3001d58ffd35SMiklos Szeredi * 300200a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 3003d58ffd35SMiklos Szeredi * 300400a07c15SAl Viro * Returns 0 on success, that is, if 300500a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 300600a07c15SAl Viro * the file was not completely opened at this time, though lookups and 300700a07c15SAl Viro * creations were performed. 300800a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 300900a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 301000a07c15SAl Viro * hadn't been specified. 30111acf0af9SDavid Howells * 301200a07c15SAl Viro * An error code is returned on failure. 3013d58ffd35SMiklos Szeredi */ 3014da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3015d58ffd35SMiklos Szeredi const struct open_flags *op, 30163ec2eef1SAl Viro bool got_write) 3017d58ffd35SMiklos Szeredi { 3018d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 301954ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30201643b43fSAl Viro int open_flag = op->open_flag; 3021d58ffd35SMiklos Szeredi struct dentry *dentry; 30221643b43fSAl Viro int error, create_error = 0; 30231643b43fSAl Viro umode_t mode = op->mode; 30246fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3025d58ffd35SMiklos Szeredi 3026ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3027da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3028d58ffd35SMiklos Szeredi 302973a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30306fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30316fbd0714SAl Viro for (;;) { 30326fbd0714SAl Viro if (!dentry) { 30336fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3034d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3035da5ebf5aSAl Viro return dentry; 30366fbd0714SAl Viro } 30376fbd0714SAl Viro if (d_in_lookup(dentry)) 30386fbd0714SAl Viro break; 3039d58ffd35SMiklos Szeredi 30406fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30416fbd0714SAl Viro if (likely(error > 0)) 30426fbd0714SAl Viro break; 30436fbd0714SAl Viro if (error) 30446fbd0714SAl Viro goto out_dput; 30456fbd0714SAl Viro d_invalidate(dentry); 30466fbd0714SAl Viro dput(dentry); 30476fbd0714SAl Viro dentry = NULL; 30486fbd0714SAl Viro } 30496fbd0714SAl Viro if (dentry->d_inode) { 3050d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3051da5ebf5aSAl Viro return dentry; 30526c51e513SAl Viro } 3053d18e9008SMiklos Szeredi 30541643b43fSAl Viro /* 30551643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30561643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30571643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30581643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30591643b43fSAl Viro * 30601643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30611643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30621643b43fSAl Viro */ 30631643b43fSAl Viro if (open_flag & O_CREAT) { 30641643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30651643b43fSAl Viro mode &= ~current_umask(); 30661643b43fSAl Viro if (unlikely(!got_write)) { 30671643b43fSAl Viro create_error = -EROFS; 30681643b43fSAl Viro open_flag &= ~O_CREAT; 30691643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30701643b43fSAl Viro goto no_open; 30711643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30721643b43fSAl Viro } else { 30731643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30741643b43fSAl Viro if (create_error) { 30751643b43fSAl Viro open_flag &= ~O_CREAT; 30761643b43fSAl Viro if (open_flag & O_EXCL) 30771643b43fSAl Viro goto no_open; 30781643b43fSAl Viro } 30791643b43fSAl Viro } 30801643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30811643b43fSAl Viro unlikely(!got_write)) { 30821643b43fSAl Viro /* 30831643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30841643b43fSAl Viro * back to lookup + open 30851643b43fSAl Viro */ 30861643b43fSAl Viro goto no_open; 3087d18e9008SMiklos Szeredi } 3088d18e9008SMiklos Szeredi 30891643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3090239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3091da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3092da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3093da5ebf5aSAl Viro return dentry; 3094239eb983SAl Viro } 309554ef4872SMiklos Szeredi 30961643b43fSAl Viro no_open: 30976fbd0714SAl Viro if (d_in_lookup(dentry)) { 309812fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 309912fa5e24SAl Viro nd->flags); 31006fbd0714SAl Viro d_lookup_done(dentry); 310112fa5e24SAl Viro if (unlikely(res)) { 310212fa5e24SAl Viro if (IS_ERR(res)) { 310312fa5e24SAl Viro error = PTR_ERR(res); 310412fa5e24SAl Viro goto out_dput; 310512fa5e24SAl Viro } 310612fa5e24SAl Viro dput(dentry); 310712fa5e24SAl Viro dentry = res; 310812fa5e24SAl Viro } 310954ef4872SMiklos Szeredi } 311054ef4872SMiklos Szeredi 3111d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31121643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 311373a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3114ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3115ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3116ce8644fcSAl Viro error = -EACCES; 3117d58ffd35SMiklos Szeredi goto out_dput; 311864894cf8SAl Viro } 3119ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31201643b43fSAl Viro open_flag & O_EXCL); 3121d58ffd35SMiklos Szeredi if (error) 3122d58ffd35SMiklos Szeredi goto out_dput; 3123ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3124d58ffd35SMiklos Szeredi } 31251643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31261643b43fSAl Viro error = create_error; 3127d58ffd35SMiklos Szeredi goto out_dput; 3128d58ffd35SMiklos Szeredi } 3129da5ebf5aSAl Viro return dentry; 3130d58ffd35SMiklos Szeredi 3131d58ffd35SMiklos Szeredi out_dput: 3132d58ffd35SMiklos Szeredi dput(dentry); 3133da5ebf5aSAl Viro return ERR_PTR(error); 3134d58ffd35SMiklos Szeredi } 3135d58ffd35SMiklos Szeredi 3136c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 31373ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3138fb1cc555SAl Viro { 3139a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3140ca344a89SAl Viro int open_flag = op->open_flag; 314164894cf8SAl Viro bool got_write = false; 3142254cf582SAl Viro unsigned seq; 3143a1eb3315SMiklos Szeredi struct inode *inode; 3144da5ebf5aSAl Viro struct dentry *dentry; 3145b0417d2cSAl Viro const char *res; 314616c2cd71SAl Viro int error; 3147fb1cc555SAl Viro 3148c3e380b0SAl Viro nd->flags |= op->intent; 3149c3e380b0SAl Viro 3150bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 315156676ec3SAl Viro if (nd->depth) 315256676ec3SAl Viro put_link(nd); 31537521f22bSAl Viro res = handle_dots(nd, nd->last_type); 31547521f22bSAl Viro if (likely(!res)) 31557521f22bSAl Viro res = ERR_PTR(complete_walk(nd)); 31567521f22bSAl Viro return res; 31571f36f774SAl Viro } 3158a2c36b45SAl Viro 3159ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3160fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3161fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3162fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 316320e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 316420e34357SAl Viro if (IS_ERR(dentry)) 31651ccac622SAl Viro return ERR_CAST(dentry); 316620e34357SAl Viro if (likely(dentry)) 316771574865SMiklos Szeredi goto finish_lookup; 316871574865SMiklos Szeredi 31696583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3170b6183df7SMiklos Szeredi } else { 3171fe2d35ffSAl Viro /* create side of things */ 3172a3fbbde7SAl Viro /* 3173b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3174b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3175b6183df7SMiklos Szeredi * about to look up 3176a3fbbde7SAl Viro */ 31779f1fafeeSAl Viro error = complete_walk(nd); 3178c981a482SAl Viro if (unlikely(error)) 31791ccac622SAl Viro return ERR_PTR(error); 3180fe2d35ffSAl Viro 3181c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 31821f36f774SAl Viro /* trailing slashes? */ 3183deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 31841ccac622SAl Viro return ERR_PTR(-EISDIR); 3185b6183df7SMiklos Szeredi } 31861f36f774SAl Viro 31879cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 318864894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 318964894cf8SAl Viro if (!error) 319064894cf8SAl Viro got_write = true; 319164894cf8SAl Viro /* 319264894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 319364894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 319464894cf8SAl Viro * dropping this one anyway. 319564894cf8SAl Viro */ 319664894cf8SAl Viro } 31979cf843e3SAl Viro if (open_flag & O_CREAT) 31985955102cSAl Viro inode_lock(dir->d_inode); 31999cf843e3SAl Viro else 32009cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3201da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 32029cf843e3SAl Viro if (open_flag & O_CREAT) 32035955102cSAl Viro inode_unlock(dir->d_inode); 32049cf843e3SAl Viro else 32059cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3206fb1cc555SAl Viro 3207c981a482SAl Viro if (got_write) 320859e96e65SAl Viro mnt_drop_write(nd->path.mnt); 32096c0d46c4SAl Viro 321059e96e65SAl Viro if (IS_ERR(dentry)) 321159e96e65SAl Viro return ERR_CAST(dentry); 321259e96e65SAl Viro 3213973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3214e73cabffSAl Viro dput(nd->path.dentry); 3215e73cabffSAl Viro nd->path.dentry = dentry; 3216c981a482SAl Viro return NULL; 3217fb1cc555SAl Viro } 3218fb1cc555SAl Viro 321920e34357SAl Viro finish_lookup: 322056676ec3SAl Viro if (nd->depth) 322156676ec3SAl Viro put_link(nd); 32228c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3223b0417d2cSAl Viro if (unlikely(res)) { 32241ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3225b0417d2cSAl Viro return res; 32261ccac622SAl Viro } 322731d1726dSAl Viro 322831d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 322931d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32301ccac622SAl Viro return ERR_PTR(-EEXIST); 323131d1726dSAl Viro } 3232c981a482SAl Viro 32338f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3234c981a482SAl Viro return ERR_PTR(complete_walk(nd)); 3235c981a482SAl Viro } 3236c981a482SAl Viro 3237c981a482SAl Viro /* 3238c981a482SAl Viro * Handle the last step of open() 3239c981a482SAl Viro */ 3240c981a482SAl Viro static const char *do_last(struct nameidata *nd, 3241c981a482SAl Viro struct file *file, const struct open_flags *op) 3242c981a482SAl Viro { 3243c981a482SAl Viro kuid_t dir_uid = nd->inode->i_uid; 3244c981a482SAl Viro umode_t dir_mode = nd->inode->i_mode; 3245c981a482SAl Viro int open_flag = op->open_flag; 3246c981a482SAl Viro bool do_truncate; 3247c981a482SAl Viro int acc_mode; 3248c981a482SAl Viro const char *link; 3249c981a482SAl Viro int error; 3250c981a482SAl Viro 3251c981a482SAl Viro link = open_last_lookups(nd, file, op); 3252c981a482SAl Viro if (unlikely(link)) 3253c981a482SAl Viro return link; 3254c981a482SAl Viro 3255973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 325676ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 325730aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 325830aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 325959e96e65SAl Viro return ERR_PTR(-EISDIR); 3260d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 326130aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 326230aba665SSalvatore Mesoraca if (unlikely(error)) 326359e96e65SAl Viro return ERR_PTR(error); 326430aba665SSalvatore Mesoraca } 326544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 326659e96e65SAl Viro return ERR_PTR(-ENOTDIR); 32676c0d46c4SAl Viro 32688795e7d4SAl Viro do_truncate = false; 32698795e7d4SAl Viro acc_mode = op->acc_mode; 32705a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32715a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32725a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32735a2d3eddSAl Viro acc_mode = 0; 32748795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32750f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32760f9d1a10SAl Viro if (error) 327759e96e65SAl Viro return ERR_PTR(error); 32788795e7d4SAl Viro do_truncate = true; 32790f9d1a10SAl Viro } 3280bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 32818795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3282ae2bb293SAl Viro error = vfs_open(&nd->path, file); 32838795e7d4SAl Viro if (!error) 32846035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 32858795e7d4SAl Viro if (!error && do_truncate) 32862675a4ebSAl Viro error = handle_truncate(file); 3287c80567c8SAl Viro if (unlikely(error > 0)) { 3288c80567c8SAl Viro WARN_ON(1); 3289c80567c8SAl Viro error = -EINVAL; 3290c80567c8SAl Viro } 32918795e7d4SAl Viro if (do_truncate) 32920f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 32931ccac622SAl Viro return ERR_PTR(error); 3294fb1cc555SAl Viro } 3295fb1cc555SAl Viro 3296af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3297af7bd4dcSAmir Goldstein { 3298af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3299af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3300af7bd4dcSAmir Goldstein struct inode *inode; 3301af7bd4dcSAmir Goldstein int error; 3302af7bd4dcSAmir Goldstein 3303af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3304af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3305af7bd4dcSAmir Goldstein if (error) 3306af7bd4dcSAmir Goldstein goto out_err; 3307af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3308af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3309af7bd4dcSAmir Goldstein goto out_err; 3310af7bd4dcSAmir Goldstein error = -ENOMEM; 3311cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3312af7bd4dcSAmir Goldstein if (unlikely(!child)) 3313af7bd4dcSAmir Goldstein goto out_err; 3314af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3315af7bd4dcSAmir Goldstein if (error) 3316af7bd4dcSAmir Goldstein goto out_err; 3317af7bd4dcSAmir Goldstein error = -ENOENT; 3318af7bd4dcSAmir Goldstein inode = child->d_inode; 3319af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3320af7bd4dcSAmir Goldstein goto out_err; 3321af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3322af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3323af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3324af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3325af7bd4dcSAmir Goldstein } 3326fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3327af7bd4dcSAmir Goldstein return child; 3328af7bd4dcSAmir Goldstein 3329af7bd4dcSAmir Goldstein out_err: 3330af7bd4dcSAmir Goldstein dput(child); 3331af7bd4dcSAmir Goldstein return ERR_PTR(error); 3332af7bd4dcSAmir Goldstein } 3333af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3334af7bd4dcSAmir Goldstein 3335c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 333660545d0dSAl Viro const struct open_flags *op, 33373ec2eef1SAl Viro struct file *file) 333860545d0dSAl Viro { 3339625b6d10SAl Viro struct dentry *child; 3340625b6d10SAl Viro struct path path; 3341c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 334260545d0dSAl Viro if (unlikely(error)) 334360545d0dSAl Viro return error; 3344625b6d10SAl Viro error = mnt_want_write(path.mnt); 334560545d0dSAl Viro if (unlikely(error)) 334660545d0dSAl Viro goto out; 3347af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3348af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3349684e73beSHirofumi Nakagawa if (IS_ERR(child)) 335060545d0dSAl Viro goto out2; 3351625b6d10SAl Viro dput(path.dentry); 3352625b6d10SAl Viro path.dentry = child; 3353c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 335469a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 335562fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 335660545d0dSAl Viro if (error) 335760545d0dSAl Viro goto out2; 3358625b6d10SAl Viro file->f_path.mnt = path.mnt; 3359be12af3eSAl Viro error = finish_open(file, child, NULL); 336060545d0dSAl Viro out2: 3361625b6d10SAl Viro mnt_drop_write(path.mnt); 336260545d0dSAl Viro out: 3363625b6d10SAl Viro path_put(&path); 336460545d0dSAl Viro return error; 336560545d0dSAl Viro } 336660545d0dSAl Viro 33676ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33686ac08709SAl Viro { 33696ac08709SAl Viro struct path path; 33706ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33716ac08709SAl Viro if (!error) { 33726ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3373ae2bb293SAl Viro error = vfs_open(&path, file); 33746ac08709SAl Viro path_put(&path); 33756ac08709SAl Viro } 33766ac08709SAl Viro return error; 33776ac08709SAl Viro } 33786ac08709SAl Viro 3379c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3380c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33811da177e4SLinus Torvalds { 338230d90494SAl Viro struct file *file; 338313aab428SAl Viro int error; 338431e6b01fSNick Piggin 3385ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 33861afc99beSAl Viro if (IS_ERR(file)) 33871afc99beSAl Viro return file; 338831e6b01fSNick Piggin 3389bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 33903ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 33915f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 33926ac08709SAl Viro error = do_o_path(nd, flags, file); 33935f336e72SAl Viro } else { 33945f336e72SAl Viro const char *s = path_init(nd, flags); 33953bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33961ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 33971ccac622SAl Viro ; 3398deb106c6SAl Viro terminate_walk(nd); 33995f336e72SAl Viro } 34007c1c01ecSAl Viro if (likely(!error)) { 3401aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 34027c1c01ecSAl Viro return file; 34037c1c01ecSAl Viro WARN_ON(1); 34047c1c01ecSAl Viro error = -EINVAL; 3405015c3bbcSMiklos Szeredi } 34067c1c01ecSAl Viro fput(file); 34072675a4ebSAl Viro if (error == -EOPENSTALE) { 34082675a4ebSAl Viro if (flags & LOOKUP_RCU) 34092675a4ebSAl Viro error = -ECHILD; 34102675a4ebSAl Viro else 34112675a4ebSAl Viro error = -ESTALE; 34122675a4ebSAl Viro } 34137c1c01ecSAl Viro return ERR_PTR(error); 3414de459215SKirill Korotaev } 34151da177e4SLinus Torvalds 3416669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3417f9652e10SAl Viro const struct open_flags *op) 341813aab428SAl Viro { 34199883d185SAl Viro struct nameidata nd; 3420f9652e10SAl Viro int flags = op->lookup_flags; 342113aab428SAl Viro struct file *filp; 342213aab428SAl Viro 34239883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3424c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 342513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3426c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 342713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3428c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34299883d185SAl Viro restore_nameidata(); 343013aab428SAl Viro return filp; 343113aab428SAl Viro } 343213aab428SAl Viro 343373d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3434f9652e10SAl Viro const char *name, const struct open_flags *op) 343573d049a4SAl Viro { 34369883d185SAl Viro struct nameidata nd; 343773d049a4SAl Viro struct file *file; 343851689104SPaul Moore struct filename *filename; 3439f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 344073d049a4SAl Viro 344173d049a4SAl Viro nd.root.mnt = mnt; 344273d049a4SAl Viro nd.root.dentry = dentry; 344373d049a4SAl Viro 3444b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 344573d049a4SAl Viro return ERR_PTR(-ELOOP); 344673d049a4SAl Viro 344751689104SPaul Moore filename = getname_kernel(name); 3448a1c83681SViresh Kumar if (IS_ERR(filename)) 344951689104SPaul Moore return ERR_CAST(filename); 345051689104SPaul Moore 34519883d185SAl Viro set_nameidata(&nd, -1, filename); 3452c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 345373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3454c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 345573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3456c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34579883d185SAl Viro restore_nameidata(); 345851689104SPaul Moore putname(filename); 345973d049a4SAl Viro return file; 346073d049a4SAl Viro } 346173d049a4SAl Viro 3462fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34631ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34641da177e4SLinus Torvalds { 3465c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3466391172c4SAl Viro struct qstr last; 3467391172c4SAl Viro int type; 3468c30dabfeSJan Kara int err2; 34691ac12b4bSJeff Layton int error; 34701ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34711ac12b4bSJeff Layton 34721ac12b4bSJeff Layton /* 34731ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34741ac12b4bSJeff Layton * other flags passed in are ignored! 34751ac12b4bSJeff Layton */ 34761ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34771ac12b4bSJeff Layton 34785c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34795c31b6ceSAl Viro if (IS_ERR(name)) 34805c31b6ceSAl Viro return ERR_CAST(name); 34811da177e4SLinus Torvalds 3482c663e5d8SChristoph Hellwig /* 3483c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3484c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3485c663e5d8SChristoph Hellwig */ 34865c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3487ed75e95dSAl Viro goto out; 3488c663e5d8SChristoph Hellwig 3489c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3490391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3491c663e5d8SChristoph Hellwig /* 3492c663e5d8SChristoph Hellwig * Do the final lookup. 3493c663e5d8SChristoph Hellwig */ 3494391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 34955955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3496391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34971da177e4SLinus Torvalds if (IS_ERR(dentry)) 3498a8104a9fSAl Viro goto unlock; 3499c663e5d8SChristoph Hellwig 3500a8104a9fSAl Viro error = -EEXIST; 3501b18825a7SDavid Howells if (d_is_positive(dentry)) 3502a8104a9fSAl Viro goto fail; 3503b18825a7SDavid Howells 3504c663e5d8SChristoph Hellwig /* 3505c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3506c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3507c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3508c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3509c663e5d8SChristoph Hellwig */ 3510391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3511a8104a9fSAl Viro error = -ENOENT; 3512ed75e95dSAl Viro goto fail; 3513e9baf6e5SAl Viro } 3514c30dabfeSJan Kara if (unlikely(err2)) { 3515c30dabfeSJan Kara error = err2; 3516a8104a9fSAl Viro goto fail; 3517c30dabfeSJan Kara } 3518181c37b6SAl Viro putname(name); 3519e9baf6e5SAl Viro return dentry; 35201da177e4SLinus Torvalds fail: 3521a8104a9fSAl Viro dput(dentry); 3522a8104a9fSAl Viro dentry = ERR_PTR(error); 3523a8104a9fSAl Viro unlock: 35245955102cSAl Viro inode_unlock(path->dentry->d_inode); 3525c30dabfeSJan Kara if (!err2) 3526391172c4SAl Viro mnt_drop_write(path->mnt); 3527ed75e95dSAl Viro out: 3528391172c4SAl Viro path_put(path); 3529181c37b6SAl Viro putname(name); 3530ed75e95dSAl Viro return dentry; 3531dae6ad8fSAl Viro } 3532fa14a0b8SAl Viro 3533fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3534fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3535fa14a0b8SAl Viro { 3536181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3537181c37b6SAl Viro path, lookup_flags); 3538fa14a0b8SAl Viro } 3539dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3540dae6ad8fSAl Viro 3541921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3542921a1650SAl Viro { 3543921a1650SAl Viro dput(dentry); 35445955102cSAl Viro inode_unlock(path->dentry->d_inode); 3545a8104a9fSAl Viro mnt_drop_write(path->mnt); 3546921a1650SAl Viro path_put(path); 3547921a1650SAl Viro } 3548921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3549921a1650SAl Viro 3550520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35511ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3552dae6ad8fSAl Viro { 3553181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3554dae6ad8fSAl Viro } 3555dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3556dae6ad8fSAl Viro 35571a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35581da177e4SLinus Torvalds { 3559a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35601da177e4SLinus Torvalds 35611da177e4SLinus Torvalds if (error) 35621da177e4SLinus Torvalds return error; 35631da177e4SLinus Torvalds 356494f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35651da177e4SLinus Torvalds return -EPERM; 35661da177e4SLinus Torvalds 3567acfa4380SAl Viro if (!dir->i_op->mknod) 35681da177e4SLinus Torvalds return -EPERM; 35691da177e4SLinus Torvalds 357008ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 357108ce5f16SSerge E. Hallyn if (error) 357208ce5f16SSerge E. Hallyn return error; 357308ce5f16SSerge E. Hallyn 35741da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35751da177e4SLinus Torvalds if (error) 35761da177e4SLinus Torvalds return error; 35771da177e4SLinus Torvalds 35781da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3579a74574aaSStephen Smalley if (!error) 3580f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35811da177e4SLinus Torvalds return error; 35821da177e4SLinus Torvalds } 35834d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35841da177e4SLinus Torvalds 3585f69aac00SAl Viro static int may_mknod(umode_t mode) 3586463c3197SDave Hansen { 3587463c3197SDave Hansen switch (mode & S_IFMT) { 3588463c3197SDave Hansen case S_IFREG: 3589463c3197SDave Hansen case S_IFCHR: 3590463c3197SDave Hansen case S_IFBLK: 3591463c3197SDave Hansen case S_IFIFO: 3592463c3197SDave Hansen case S_IFSOCK: 3593463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3594463c3197SDave Hansen return 0; 3595463c3197SDave Hansen case S_IFDIR: 3596463c3197SDave Hansen return -EPERM; 3597463c3197SDave Hansen default: 3598463c3197SDave Hansen return -EINVAL; 3599463c3197SDave Hansen } 3600463c3197SDave Hansen } 3601463c3197SDave Hansen 360287c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 360387c4e192SDominik Brodowski unsigned int dev) 36041da177e4SLinus Torvalds { 36051da177e4SLinus Torvalds struct dentry *dentry; 3606dae6ad8fSAl Viro struct path path; 3607dae6ad8fSAl Viro int error; 3608972567f1SJeff Layton unsigned int lookup_flags = 0; 36091da177e4SLinus Torvalds 36108e4bfca1SAl Viro error = may_mknod(mode); 36118e4bfca1SAl Viro if (error) 36128e4bfca1SAl Viro return error; 3613972567f1SJeff Layton retry: 3614972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3615dae6ad8fSAl Viro if (IS_ERR(dentry)) 3616dae6ad8fSAl Viro return PTR_ERR(dentry); 36172ad94ae6SAl Viro 3618dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3619ce3b0f8dSAl Viro mode &= ~current_umask(); 3620dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3621be6d3e56SKentaro Takeda if (error) 3622a8104a9fSAl Viro goto out; 36231da177e4SLinus Torvalds switch (mode & S_IFMT) { 36241da177e4SLinus Torvalds case 0: case S_IFREG: 3625312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 362605d1a717SMimi Zohar if (!error) 362705d1a717SMimi Zohar ima_post_path_mknod(dentry); 36281da177e4SLinus Torvalds break; 36291da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3630dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36311da177e4SLinus Torvalds new_decode_dev(dev)); 36321da177e4SLinus Torvalds break; 36331da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3634dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36351da177e4SLinus Torvalds break; 36361da177e4SLinus Torvalds } 3637a8104a9fSAl Viro out: 3638921a1650SAl Viro done_path_create(&path, dentry); 3639972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3640972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3641972567f1SJeff Layton goto retry; 3642972567f1SJeff Layton } 36431da177e4SLinus Torvalds return error; 36441da177e4SLinus Torvalds } 36451da177e4SLinus Torvalds 364687c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 364787c4e192SDominik Brodowski unsigned int, dev) 364887c4e192SDominik Brodowski { 364987c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 365087c4e192SDominik Brodowski } 365187c4e192SDominik Brodowski 36528208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36535590ff0dSUlrich Drepper { 365487c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36555590ff0dSUlrich Drepper } 36565590ff0dSUlrich Drepper 365718bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36581da177e4SLinus Torvalds { 3659a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36608de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36611da177e4SLinus Torvalds 36621da177e4SLinus Torvalds if (error) 36631da177e4SLinus Torvalds return error; 36641da177e4SLinus Torvalds 3665acfa4380SAl Viro if (!dir->i_op->mkdir) 36661da177e4SLinus Torvalds return -EPERM; 36671da177e4SLinus Torvalds 36681da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36691da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36701da177e4SLinus Torvalds if (error) 36711da177e4SLinus Torvalds return error; 36721da177e4SLinus Torvalds 36738de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36748de52778SAl Viro return -EMLINK; 36758de52778SAl Viro 36761da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3677a74574aaSStephen Smalley if (!error) 3678f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36791da177e4SLinus Torvalds return error; 36801da177e4SLinus Torvalds } 36814d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36821da177e4SLinus Torvalds 36830101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 36841da177e4SLinus Torvalds { 36856902d925SDave Hansen struct dentry *dentry; 3686dae6ad8fSAl Viro struct path path; 3687dae6ad8fSAl Viro int error; 3688b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36891da177e4SLinus Torvalds 3690b76d8b82SJeff Layton retry: 3691b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36926902d925SDave Hansen if (IS_ERR(dentry)) 3693dae6ad8fSAl Viro return PTR_ERR(dentry); 36946902d925SDave Hansen 3695dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3696ce3b0f8dSAl Viro mode &= ~current_umask(); 3697dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3698a8104a9fSAl Viro if (!error) 3699dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3700921a1650SAl Viro done_path_create(&path, dentry); 3701b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3702b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3703b76d8b82SJeff Layton goto retry; 3704b76d8b82SJeff Layton } 37051da177e4SLinus Torvalds return error; 37061da177e4SLinus Torvalds } 37071da177e4SLinus Torvalds 37080101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37090101db7aSDominik Brodowski { 37100101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37110101db7aSDominik Brodowski } 37120101db7aSDominik Brodowski 3713a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37145590ff0dSUlrich Drepper { 37150101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37165590ff0dSUlrich Drepper } 37175590ff0dSUlrich Drepper 37181da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37191da177e4SLinus Torvalds { 37201da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37211da177e4SLinus Torvalds 37221da177e4SLinus Torvalds if (error) 37231da177e4SLinus Torvalds return error; 37241da177e4SLinus Torvalds 3725acfa4380SAl Viro if (!dir->i_op->rmdir) 37261da177e4SLinus Torvalds return -EPERM; 37271da177e4SLinus Torvalds 37281d2ef590SAl Viro dget(dentry); 37295955102cSAl Viro inode_lock(dentry->d_inode); 3730912dbc15SSage Weil 37311da177e4SLinus Torvalds error = -EBUSY; 37327af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3733912dbc15SSage Weil goto out; 3734912dbc15SSage Weil 37351da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3736912dbc15SSage Weil if (error) 3737912dbc15SSage Weil goto out; 3738912dbc15SSage Weil 37391da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3740912dbc15SSage Weil if (error) 3741912dbc15SSage Weil goto out; 3742912dbc15SSage Weil 37438767712fSAl Viro shrink_dcache_parent(dentry); 37441da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3745d83c49f3SAl Viro dont_mount(dentry); 37468ed936b5SEric W. Biederman detach_mounts(dentry); 3747116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37481da177e4SLinus Torvalds 3749912dbc15SSage Weil out: 37505955102cSAl Viro inode_unlock(dentry->d_inode); 37511d2ef590SAl Viro dput(dentry); 3752912dbc15SSage Weil if (!error) 3753912dbc15SSage Weil d_delete(dentry); 37541da177e4SLinus Torvalds return error; 37551da177e4SLinus Torvalds } 37564d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37571da177e4SLinus Torvalds 3758f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37591da177e4SLinus Torvalds { 37601da177e4SLinus Torvalds int error = 0; 376191a27b2aSJeff Layton struct filename *name; 37621da177e4SLinus Torvalds struct dentry *dentry; 3763f5beed75SAl Viro struct path path; 3764f5beed75SAl Viro struct qstr last; 3765f5beed75SAl Viro int type; 3766c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3767c6ee9206SJeff Layton retry: 3768c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3769c1d4dd27SAl Viro &path, &last, &type); 377091a27b2aSJeff Layton if (IS_ERR(name)) 377191a27b2aSJeff Layton return PTR_ERR(name); 37721da177e4SLinus Torvalds 3773f5beed75SAl Viro switch (type) { 37741da177e4SLinus Torvalds case LAST_DOTDOT: 37751da177e4SLinus Torvalds error = -ENOTEMPTY; 37761da177e4SLinus Torvalds goto exit1; 37771da177e4SLinus Torvalds case LAST_DOT: 37781da177e4SLinus Torvalds error = -EINVAL; 37791da177e4SLinus Torvalds goto exit1; 37801da177e4SLinus Torvalds case LAST_ROOT: 37811da177e4SLinus Torvalds error = -EBUSY; 37821da177e4SLinus Torvalds goto exit1; 37831da177e4SLinus Torvalds } 37840612d9fbSOGAWA Hirofumi 3785f5beed75SAl Viro error = mnt_want_write(path.mnt); 3786c30dabfeSJan Kara if (error) 3787c30dabfeSJan Kara goto exit1; 37880612d9fbSOGAWA Hirofumi 37895955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3790f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37911da177e4SLinus Torvalds error = PTR_ERR(dentry); 37926902d925SDave Hansen if (IS_ERR(dentry)) 37936902d925SDave Hansen goto exit2; 3794e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3795e6bc45d6STheodore Ts'o error = -ENOENT; 3796e6bc45d6STheodore Ts'o goto exit3; 3797e6bc45d6STheodore Ts'o } 3798f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3799be6d3e56SKentaro Takeda if (error) 3800c30dabfeSJan Kara goto exit3; 3801f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 38020622753bSDave Hansen exit3: 38031da177e4SLinus Torvalds dput(dentry); 38046902d925SDave Hansen exit2: 38055955102cSAl Viro inode_unlock(path.dentry->d_inode); 3806f5beed75SAl Viro mnt_drop_write(path.mnt); 38071da177e4SLinus Torvalds exit1: 3808f5beed75SAl Viro path_put(&path); 38091da177e4SLinus Torvalds putname(name); 3810c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3811c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3812c6ee9206SJeff Layton goto retry; 3813c6ee9206SJeff Layton } 38141da177e4SLinus Torvalds return error; 38151da177e4SLinus Torvalds } 38161da177e4SLinus Torvalds 38173cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38185590ff0dSUlrich Drepper { 38195590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38205590ff0dSUlrich Drepper } 38215590ff0dSUlrich Drepper 3822b21996e3SJ. Bruce Fields /** 3823b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3824b21996e3SJ. Bruce Fields * @dir: parent directory 3825b21996e3SJ. Bruce Fields * @dentry: victim 3826b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3827b21996e3SJ. Bruce Fields * 3828b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3829b21996e3SJ. Bruce Fields * 3830b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3831b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3832b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3833b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3834b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3835b21996e3SJ. Bruce Fields * 3836b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3837b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3838b21996e3SJ. Bruce Fields * to be NFS exported. 3839b21996e3SJ. Bruce Fields */ 3840b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38411da177e4SLinus Torvalds { 38429accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38431da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38441da177e4SLinus Torvalds 38451da177e4SLinus Torvalds if (error) 38461da177e4SLinus Torvalds return error; 38471da177e4SLinus Torvalds 3848acfa4380SAl Viro if (!dir->i_op->unlink) 38491da177e4SLinus Torvalds return -EPERM; 38501da177e4SLinus Torvalds 38515955102cSAl Viro inode_lock(target); 38528ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38531da177e4SLinus Torvalds error = -EBUSY; 38541da177e4SLinus Torvalds else { 38551da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3856bec1052eSAl Viro if (!error) { 38575a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38585a14696cSJ. Bruce Fields if (error) 3859b21996e3SJ. Bruce Fields goto out; 38601da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38618ed936b5SEric W. Biederman if (!error) { 3862d83c49f3SAl Viro dont_mount(dentry); 38638ed936b5SEric W. Biederman detach_mounts(dentry); 3864116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38658ed936b5SEric W. Biederman } 3866bec1052eSAl Viro } 38671da177e4SLinus Torvalds } 3868b21996e3SJ. Bruce Fields out: 38695955102cSAl Viro inode_unlock(target); 38701da177e4SLinus Torvalds 38711da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38721da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38739accbb97SJ. Bruce Fields fsnotify_link_count(target); 38741da177e4SLinus Torvalds d_delete(dentry); 38751da177e4SLinus Torvalds } 38760eeca283SRobert Love 38771da177e4SLinus Torvalds return error; 38781da177e4SLinus Torvalds } 38794d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38801da177e4SLinus Torvalds 38811da177e4SLinus Torvalds /* 38821da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38831b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38841da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38851da177e4SLinus Torvalds * while waiting on the I/O. 38861da177e4SLinus Torvalds */ 3887da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 38881da177e4SLinus Torvalds { 38892ad94ae6SAl Viro int error; 38901da177e4SLinus Torvalds struct dentry *dentry; 3891f5beed75SAl Viro struct path path; 3892f5beed75SAl Viro struct qstr last; 3893f5beed75SAl Viro int type; 38941da177e4SLinus Torvalds struct inode *inode = NULL; 3895b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38965d18f813SJeff Layton unsigned int lookup_flags = 0; 38975d18f813SJeff Layton retry: 3898da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 389991a27b2aSJeff Layton if (IS_ERR(name)) 390091a27b2aSJeff Layton return PTR_ERR(name); 39012ad94ae6SAl Viro 39021da177e4SLinus Torvalds error = -EISDIR; 3903f5beed75SAl Viro if (type != LAST_NORM) 39041da177e4SLinus Torvalds goto exit1; 39050612d9fbSOGAWA Hirofumi 3906f5beed75SAl Viro error = mnt_want_write(path.mnt); 3907c30dabfeSJan Kara if (error) 3908c30dabfeSJan Kara goto exit1; 3909b21996e3SJ. Bruce Fields retry_deleg: 39105955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3911f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39121da177e4SLinus Torvalds error = PTR_ERR(dentry); 39131da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39141da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3915f5beed75SAl Viro if (last.name[last.len]) 391650338b88STörök Edwin goto slashes; 39171da177e4SLinus Torvalds inode = dentry->d_inode; 3918b18825a7SDavid Howells if (d_is_negative(dentry)) 3919e6bc45d6STheodore Ts'o goto slashes; 39207de9c6eeSAl Viro ihold(inode); 3921f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3922be6d3e56SKentaro Takeda if (error) 3923c30dabfeSJan Kara goto exit2; 3924f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39251da177e4SLinus Torvalds exit2: 39261da177e4SLinus Torvalds dput(dentry); 39271da177e4SLinus Torvalds } 39285955102cSAl Viro inode_unlock(path.dentry->d_inode); 39291da177e4SLinus Torvalds if (inode) 39301da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3931b21996e3SJ. Bruce Fields inode = NULL; 3932b21996e3SJ. Bruce Fields if (delegated_inode) { 39335a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3934b21996e3SJ. Bruce Fields if (!error) 3935b21996e3SJ. Bruce Fields goto retry_deleg; 3936b21996e3SJ. Bruce Fields } 3937f5beed75SAl Viro mnt_drop_write(path.mnt); 39381da177e4SLinus Torvalds exit1: 3939f5beed75SAl Viro path_put(&path); 39405d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39415d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39425d18f813SJeff Layton inode = NULL; 39435d18f813SJeff Layton goto retry; 39445d18f813SJeff Layton } 3945da2f1362SChristoph Hellwig putname(name); 39461da177e4SLinus Torvalds return error; 39471da177e4SLinus Torvalds 39481da177e4SLinus Torvalds slashes: 3949b18825a7SDavid Howells if (d_is_negative(dentry)) 3950b18825a7SDavid Howells error = -ENOENT; 395144b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3952b18825a7SDavid Howells error = -EISDIR; 3953b18825a7SDavid Howells else 3954b18825a7SDavid Howells error = -ENOTDIR; 39551da177e4SLinus Torvalds goto exit2; 39561da177e4SLinus Torvalds } 39571da177e4SLinus Torvalds 39582e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39595590ff0dSUlrich Drepper { 39605590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39615590ff0dSUlrich Drepper return -EINVAL; 39625590ff0dSUlrich Drepper 39635590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39645590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39655590ff0dSUlrich Drepper 3966da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39675590ff0dSUlrich Drepper } 39685590ff0dSUlrich Drepper 39693480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39705590ff0dSUlrich Drepper { 3971da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39725590ff0dSUlrich Drepper } 39735590ff0dSUlrich Drepper 3974db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39751da177e4SLinus Torvalds { 3976a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39771da177e4SLinus Torvalds 39781da177e4SLinus Torvalds if (error) 39791da177e4SLinus Torvalds return error; 39801da177e4SLinus Torvalds 3981acfa4380SAl Viro if (!dir->i_op->symlink) 39821da177e4SLinus Torvalds return -EPERM; 39831da177e4SLinus Torvalds 39841da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39851da177e4SLinus Torvalds if (error) 39861da177e4SLinus Torvalds return error; 39871da177e4SLinus Torvalds 39881da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3989a74574aaSStephen Smalley if (!error) 3990f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39911da177e4SLinus Torvalds return error; 39921da177e4SLinus Torvalds } 39934d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39941da177e4SLinus Torvalds 3995b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 3996b724e846SDominik Brodowski const char __user *newname) 39971da177e4SLinus Torvalds { 39982ad94ae6SAl Viro int error; 399991a27b2aSJeff Layton struct filename *from; 40006902d925SDave Hansen struct dentry *dentry; 4001dae6ad8fSAl Viro struct path path; 4002f46d3567SJeff Layton unsigned int lookup_flags = 0; 40031da177e4SLinus Torvalds 40041da177e4SLinus Torvalds from = getname(oldname); 40051da177e4SLinus Torvalds if (IS_ERR(from)) 40061da177e4SLinus Torvalds return PTR_ERR(from); 4007f46d3567SJeff Layton retry: 4008f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40091da177e4SLinus Torvalds error = PTR_ERR(dentry); 40106902d925SDave Hansen if (IS_ERR(dentry)) 4011dae6ad8fSAl Viro goto out_putname; 40126902d925SDave Hansen 401391a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4014a8104a9fSAl Viro if (!error) 401591a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4016921a1650SAl Viro done_path_create(&path, dentry); 4017f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4018f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4019f46d3567SJeff Layton goto retry; 4020f46d3567SJeff Layton } 40216902d925SDave Hansen out_putname: 40221da177e4SLinus Torvalds putname(from); 40231da177e4SLinus Torvalds return error; 40241da177e4SLinus Torvalds } 40251da177e4SLinus Torvalds 4026b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4027b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4028b724e846SDominik Brodowski { 4029b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4030b724e846SDominik Brodowski } 4031b724e846SDominik Brodowski 40323480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40335590ff0dSUlrich Drepper { 4034b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40355590ff0dSUlrich Drepper } 40365590ff0dSUlrich Drepper 4037146a8595SJ. Bruce Fields /** 4038146a8595SJ. Bruce Fields * vfs_link - create a new link 4039146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4040146a8595SJ. Bruce Fields * @dir: new parent 4041146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4042146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4043146a8595SJ. Bruce Fields * 4044146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4045146a8595SJ. Bruce Fields * 4046146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4047146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4048146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4049146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4050146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4051146a8595SJ. Bruce Fields * 4052146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4053146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4054146a8595SJ. Bruce Fields * to be NFS exported. 4055146a8595SJ. Bruce Fields */ 4056146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40571da177e4SLinus Torvalds { 40581da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40598de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40601da177e4SLinus Torvalds int error; 40611da177e4SLinus Torvalds 40621da177e4SLinus Torvalds if (!inode) 40631da177e4SLinus Torvalds return -ENOENT; 40641da177e4SLinus Torvalds 4065a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40661da177e4SLinus Torvalds if (error) 40671da177e4SLinus Torvalds return error; 40681da177e4SLinus Torvalds 40691da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40701da177e4SLinus Torvalds return -EXDEV; 40711da177e4SLinus Torvalds 40721da177e4SLinus Torvalds /* 40731da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40741da177e4SLinus Torvalds */ 40751da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40761da177e4SLinus Torvalds return -EPERM; 40770bd23d09SEric W. Biederman /* 40780bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 40790bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 40800bd23d09SEric W. Biederman * the vfs. 40810bd23d09SEric W. Biederman */ 40820bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 40830bd23d09SEric W. Biederman return -EPERM; 4084acfa4380SAl Viro if (!dir->i_op->link) 40851da177e4SLinus Torvalds return -EPERM; 40867e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40871da177e4SLinus Torvalds return -EPERM; 40881da177e4SLinus Torvalds 40891da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40901da177e4SLinus Torvalds if (error) 40911da177e4SLinus Torvalds return error; 40921da177e4SLinus Torvalds 40935955102cSAl Viro inode_lock(inode); 4094aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4095f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4096aae8a97dSAneesh Kumar K.V error = -ENOENT; 40978de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40988de52778SAl Viro error = -EMLINK; 4099146a8595SJ. Bruce Fields else { 4100146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4101146a8595SJ. Bruce Fields if (!error) 41021da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4103146a8595SJ. Bruce Fields } 4104f4e0c30cSAl Viro 4105f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4106f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4107f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4108f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4109f4e0c30cSAl Viro } 41105955102cSAl Viro inode_unlock(inode); 4111e31e14ecSStephen Smalley if (!error) 41127e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41131da177e4SLinus Torvalds return error; 41141da177e4SLinus Torvalds } 41154d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41161da177e4SLinus Torvalds 41171da177e4SLinus Torvalds /* 41181da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41191da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41201da177e4SLinus Torvalds * newname. --KAB 41211da177e4SLinus Torvalds * 41221da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41231da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41241da177e4SLinus Torvalds * and other special files. --ADM 41251da177e4SLinus Torvalds */ 412646ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 412746ea89ebSDominik Brodowski const char __user *newname, int flags) 41281da177e4SLinus Torvalds { 41291da177e4SLinus Torvalds struct dentry *new_dentry; 4130dae6ad8fSAl Viro struct path old_path, new_path; 4131146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 413211a7b371SAneesh Kumar K.V int how = 0; 41331da177e4SLinus Torvalds int error; 41341da177e4SLinus Torvalds 413511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4136c04030e1SUlrich Drepper return -EINVAL; 413711a7b371SAneesh Kumar K.V /* 4138f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4139f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4140f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 414111a7b371SAneesh Kumar K.V */ 4142f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4143f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4144f0cc6ffbSLinus Torvalds return -ENOENT; 414511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4146f0cc6ffbSLinus Torvalds } 4147c04030e1SUlrich Drepper 414811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 414911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4150442e31caSJeff Layton retry: 415111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41521da177e4SLinus Torvalds if (error) 41532ad94ae6SAl Viro return error; 41542ad94ae6SAl Viro 4155442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4156442e31caSJeff Layton (how & LOOKUP_REVAL)); 41571da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41586902d925SDave Hansen if (IS_ERR(new_dentry)) 4159dae6ad8fSAl Viro goto out; 4160dae6ad8fSAl Viro 4161dae6ad8fSAl Viro error = -EXDEV; 4162dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4163dae6ad8fSAl Viro goto out_dput; 4164800179c9SKees Cook error = may_linkat(&old_path); 4165800179c9SKees Cook if (unlikely(error)) 4166800179c9SKees Cook goto out_dput; 4167dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4168be6d3e56SKentaro Takeda if (error) 4169a8104a9fSAl Viro goto out_dput; 4170146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 417175c3f29dSDave Hansen out_dput: 4172921a1650SAl Viro done_path_create(&new_path, new_dentry); 4173146a8595SJ. Bruce Fields if (delegated_inode) { 4174146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4175d22e6338SOleg Drokin if (!error) { 4176d22e6338SOleg Drokin path_put(&old_path); 4177146a8595SJ. Bruce Fields goto retry; 4178146a8595SJ. Bruce Fields } 4179d22e6338SOleg Drokin } 4180442e31caSJeff Layton if (retry_estale(error, how)) { 4181d22e6338SOleg Drokin path_put(&old_path); 4182442e31caSJeff Layton how |= LOOKUP_REVAL; 4183442e31caSJeff Layton goto retry; 4184442e31caSJeff Layton } 41851da177e4SLinus Torvalds out: 41862d8f3038SAl Viro path_put(&old_path); 41871da177e4SLinus Torvalds 41881da177e4SLinus Torvalds return error; 41891da177e4SLinus Torvalds } 41901da177e4SLinus Torvalds 419146ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 419246ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 419346ea89ebSDominik Brodowski { 419446ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 419546ea89ebSDominik Brodowski } 419646ea89ebSDominik Brodowski 41973480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41985590ff0dSUlrich Drepper { 419946ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42005590ff0dSUlrich Drepper } 42015590ff0dSUlrich Drepper 4202bc27027aSMiklos Szeredi /** 4203bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4204bc27027aSMiklos Szeredi * @old_dir: parent of source 4205bc27027aSMiklos Szeredi * @old_dentry: source 4206bc27027aSMiklos Szeredi * @new_dir: parent of destination 4207bc27027aSMiklos Szeredi * @new_dentry: destination 4208bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4209520c8b16SMiklos Szeredi * @flags: rename flags 4210bc27027aSMiklos Szeredi * 4211bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4212bc27027aSMiklos Szeredi * 4213bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4214bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4215bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4216bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4217bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4218bc27027aSMiklos Szeredi * so. 4219bc27027aSMiklos Szeredi * 4220bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4221bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4222bc27027aSMiklos Szeredi * to be NFS exported. 4223bc27027aSMiklos Szeredi * 42241da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42251da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42261da177e4SLinus Torvalds * Problems: 42270117d427SMauro Carvalho Chehab * 4228d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42291da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42301da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4231a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42321da177e4SLinus Torvalds * story. 42336cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42346cedba89SJ. Bruce Fields * and source (if it is not a directory). 42351b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42361da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42371da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4238a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42391da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42401da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42411da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4242a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42431da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42441da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42451da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4246e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42471b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42481da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4249c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42501da177e4SLinus Torvalds * locking]. 42511da177e4SLinus Torvalds */ 42521da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42538e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4254520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42551da177e4SLinus Torvalds { 42561da177e4SLinus Torvalds int error; 4257bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4258bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4259bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4260da1ce067SMiklos Szeredi bool new_is_dir = false; 4261da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 426249d31c2fSAl Viro struct name_snapshot old_name; 42631da177e4SLinus Torvalds 42648d3e2936SMiklos Szeredi if (source == target) 42651da177e4SLinus Torvalds return 0; 42661da177e4SLinus Torvalds 42671da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42681da177e4SLinus Torvalds if (error) 42691da177e4SLinus Torvalds return error; 42701da177e4SLinus Torvalds 4271da1ce067SMiklos Szeredi if (!target) { 4272a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4273da1ce067SMiklos Szeredi } else { 4274da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4275da1ce067SMiklos Szeredi 4276da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42771da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4278da1ce067SMiklos Szeredi else 4279da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4280da1ce067SMiklos Szeredi } 42811da177e4SLinus Torvalds if (error) 42821da177e4SLinus Torvalds return error; 42831da177e4SLinus Torvalds 42842773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 42851da177e4SLinus Torvalds return -EPERM; 42861da177e4SLinus Torvalds 4287bc27027aSMiklos Szeredi /* 4288bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4289bc27027aSMiklos Szeredi * we'll need to flip '..'. 4290bc27027aSMiklos Szeredi */ 4291da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4292da1ce067SMiklos Szeredi if (is_dir) { 4293bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4294bc27027aSMiklos Szeredi if (error) 4295bc27027aSMiklos Szeredi return error; 4296bc27027aSMiklos Szeredi } 4297da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4298da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4299da1ce067SMiklos Szeredi if (error) 4300da1ce067SMiklos Szeredi return error; 4301da1ce067SMiklos Szeredi } 4302da1ce067SMiklos Szeredi } 43030eeca283SRobert Love 43040b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43050b3974ebSMiklos Szeredi flags); 4306bc27027aSMiklos Szeredi if (error) 4307bc27027aSMiklos Szeredi return error; 4308bc27027aSMiklos Szeredi 430949d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4310bc27027aSMiklos Szeredi dget(new_dentry); 4311da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4312bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4313bc27027aSMiklos Szeredi else if (target) 43145955102cSAl Viro inode_lock(target); 4315bc27027aSMiklos Szeredi 4316bc27027aSMiklos Szeredi error = -EBUSY; 43177af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4318bc27027aSMiklos Szeredi goto out; 4319bc27027aSMiklos Szeredi 4320da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4321bc27027aSMiklos Szeredi error = -EMLINK; 4322da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4323bc27027aSMiklos Szeredi goto out; 4324da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4325da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4326da1ce067SMiklos Szeredi goto out; 4327da1ce067SMiklos Szeredi } 4328da1ce067SMiklos Szeredi if (!is_dir) { 4329bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4330bc27027aSMiklos Szeredi if (error) 4331bc27027aSMiklos Szeredi goto out; 4332da1ce067SMiklos Szeredi } 4333da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4334bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4335bc27027aSMiklos Szeredi if (error) 4336bc27027aSMiklos Szeredi goto out; 4337bc27027aSMiklos Szeredi } 4338520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4339520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4340bc27027aSMiklos Szeredi if (error) 4341bc27027aSMiklos Szeredi goto out; 4342bc27027aSMiklos Szeredi 4343da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43448767712fSAl Viro if (is_dir) { 43458767712fSAl Viro shrink_dcache_parent(new_dentry); 4346bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43478767712fSAl Viro } 4348bc27027aSMiklos Szeredi dont_mount(new_dentry); 43498ed936b5SEric W. Biederman detach_mounts(new_dentry); 4350bc27027aSMiklos Szeredi } 4351da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4352da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4353bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4354da1ce067SMiklos Szeredi else 4355da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4356da1ce067SMiklos Szeredi } 4357bc27027aSMiklos Szeredi out: 4358da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4359bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4360bc27027aSMiklos Szeredi else if (target) 43615955102cSAl Viro inode_unlock(target); 4362bc27027aSMiklos Szeredi dput(new_dentry); 4363da1ce067SMiklos Szeredi if (!error) { 4364f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4365da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4366da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4367f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4368da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4369da1ce067SMiklos Szeredi } 4370da1ce067SMiklos Szeredi } 437149d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 43720eeca283SRobert Love 43731da177e4SLinus Torvalds return error; 43741da177e4SLinus Torvalds } 43754d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43761da177e4SLinus Torvalds 4377ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4378ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 43791da177e4SLinus Torvalds { 43801da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43811da177e4SLinus Torvalds struct dentry *trap; 4382f5beed75SAl Viro struct path old_path, new_path; 4383f5beed75SAl Viro struct qstr old_last, new_last; 4384f5beed75SAl Viro int old_type, new_type; 43858e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 438691a27b2aSJeff Layton struct filename *from; 438791a27b2aSJeff Layton struct filename *to; 4388f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4389c6a94284SJeff Layton bool should_retry = false; 43902ad94ae6SAl Viro int error; 4391520c8b16SMiklos Szeredi 43920d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4393da1ce067SMiklos Szeredi return -EINVAL; 4394da1ce067SMiklos Szeredi 43950d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43960d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4397520c8b16SMiklos Szeredi return -EINVAL; 4398520c8b16SMiklos Szeredi 43990d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44000d7a8555SMiklos Szeredi return -EPERM; 44010d7a8555SMiklos Szeredi 4402f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4403f5beed75SAl Viro target_flags = 0; 4404f5beed75SAl Viro 4405c6a94284SJeff Layton retry: 4406c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4407c1d4dd27SAl Viro &old_path, &old_last, &old_type); 440891a27b2aSJeff Layton if (IS_ERR(from)) { 440991a27b2aSJeff Layton error = PTR_ERR(from); 44101da177e4SLinus Torvalds goto exit; 441191a27b2aSJeff Layton } 44121da177e4SLinus Torvalds 4413c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4414c1d4dd27SAl Viro &new_path, &new_last, &new_type); 441591a27b2aSJeff Layton if (IS_ERR(to)) { 441691a27b2aSJeff Layton error = PTR_ERR(to); 44171da177e4SLinus Torvalds goto exit1; 441891a27b2aSJeff Layton } 44191da177e4SLinus Torvalds 44201da177e4SLinus Torvalds error = -EXDEV; 4421f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44221da177e4SLinus Torvalds goto exit2; 44231da177e4SLinus Torvalds 44241da177e4SLinus Torvalds error = -EBUSY; 4425f5beed75SAl Viro if (old_type != LAST_NORM) 44261da177e4SLinus Torvalds goto exit2; 44271da177e4SLinus Torvalds 44280a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44290a7c3937SMiklos Szeredi error = -EEXIST; 4430f5beed75SAl Viro if (new_type != LAST_NORM) 44311da177e4SLinus Torvalds goto exit2; 44321da177e4SLinus Torvalds 4433f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4434c30dabfeSJan Kara if (error) 4435c30dabfeSJan Kara goto exit2; 4436c30dabfeSJan Kara 44378e6d782cSJ. Bruce Fields retry_deleg: 4438f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44391da177e4SLinus Torvalds 4440f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44411da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44421da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44431da177e4SLinus Torvalds goto exit3; 44441da177e4SLinus Torvalds /* source must exist */ 44451da177e4SLinus Torvalds error = -ENOENT; 4446b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44471da177e4SLinus Torvalds goto exit4; 4448f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44491da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44501da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44511da177e4SLinus Torvalds goto exit4; 44520a7c3937SMiklos Szeredi error = -EEXIST; 44530a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44540a7c3937SMiklos Szeredi goto exit5; 4455da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4456da1ce067SMiklos Szeredi error = -ENOENT; 4457da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4458da1ce067SMiklos Szeredi goto exit5; 4459da1ce067SMiklos Szeredi 4460da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4461da1ce067SMiklos Szeredi error = -ENOTDIR; 4462f5beed75SAl Viro if (new_last.name[new_last.len]) 4463da1ce067SMiklos Szeredi goto exit5; 4464da1ce067SMiklos Szeredi } 4465da1ce067SMiklos Szeredi } 44660a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44670a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44680a7c3937SMiklos Szeredi error = -ENOTDIR; 4469f5beed75SAl Viro if (old_last.name[old_last.len]) 44700a7c3937SMiklos Szeredi goto exit5; 4471f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44720a7c3937SMiklos Szeredi goto exit5; 44730a7c3937SMiklos Szeredi } 44740a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44750a7c3937SMiklos Szeredi error = -EINVAL; 44760a7c3937SMiklos Szeredi if (old_dentry == trap) 44770a7c3937SMiklos Szeredi goto exit5; 44781da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4479da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44801da177e4SLinus Torvalds error = -ENOTEMPTY; 44811da177e4SLinus Torvalds if (new_dentry == trap) 44821da177e4SLinus Torvalds goto exit5; 44831da177e4SLinus Torvalds 4484f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4485f5beed75SAl Viro &new_path, new_dentry, flags); 4486be6d3e56SKentaro Takeda if (error) 4487c30dabfeSJan Kara goto exit5; 4488f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4489f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4490520c8b16SMiklos Szeredi &delegated_inode, flags); 44911da177e4SLinus Torvalds exit5: 44921da177e4SLinus Torvalds dput(new_dentry); 44931da177e4SLinus Torvalds exit4: 44941da177e4SLinus Torvalds dput(old_dentry); 44951da177e4SLinus Torvalds exit3: 4496f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44978e6d782cSJ. Bruce Fields if (delegated_inode) { 44988e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44998e6d782cSJ. Bruce Fields if (!error) 45008e6d782cSJ. Bruce Fields goto retry_deleg; 45018e6d782cSJ. Bruce Fields } 4502f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45031da177e4SLinus Torvalds exit2: 4504c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4505c6a94284SJeff Layton should_retry = true; 4506f5beed75SAl Viro path_put(&new_path); 45072ad94ae6SAl Viro putname(to); 45081da177e4SLinus Torvalds exit1: 4509f5beed75SAl Viro path_put(&old_path); 45101da177e4SLinus Torvalds putname(from); 4511c6a94284SJeff Layton if (should_retry) { 4512c6a94284SJeff Layton should_retry = false; 4513c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4514c6a94284SJeff Layton goto retry; 4515c6a94284SJeff Layton } 45162ad94ae6SAl Viro exit: 45171da177e4SLinus Torvalds return error; 45181da177e4SLinus Torvalds } 45191da177e4SLinus Torvalds 4520ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4521ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4522ee81feb6SDominik Brodowski { 4523ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4524ee81feb6SDominik Brodowski } 4525ee81feb6SDominik Brodowski 4526520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4527520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4528520c8b16SMiklos Szeredi { 4529ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4530520c8b16SMiklos Szeredi } 4531520c8b16SMiklos Szeredi 4532a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45335590ff0dSUlrich Drepper { 4534ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45355590ff0dSUlrich Drepper } 45365590ff0dSUlrich Drepper 4537787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4538787fb6bcSMiklos Szeredi { 4539787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4540787fb6bcSMiklos Szeredi if (error) 4541787fb6bcSMiklos Szeredi return error; 4542787fb6bcSMiklos Szeredi 4543787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4544787fb6bcSMiklos Szeredi return -EPERM; 4545787fb6bcSMiklos Szeredi 4546787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4547787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4548787fb6bcSMiklos Szeredi } 4549787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4550787fb6bcSMiklos Szeredi 45515d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45521da177e4SLinus Torvalds { 45535d826c84SAl Viro int len = PTR_ERR(link); 45541da177e4SLinus Torvalds if (IS_ERR(link)) 45551da177e4SLinus Torvalds goto out; 45561da177e4SLinus Torvalds 45571da177e4SLinus Torvalds len = strlen(link); 45581da177e4SLinus Torvalds if (len > (unsigned) buflen) 45591da177e4SLinus Torvalds len = buflen; 45601da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45611da177e4SLinus Torvalds len = -EFAULT; 45621da177e4SLinus Torvalds out: 45631da177e4SLinus Torvalds return len; 45641da177e4SLinus Torvalds } 45651da177e4SLinus Torvalds 4566d60874cdSMiklos Szeredi /** 4567fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4568fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4569fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4570fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4571fd4a0edfSMiklos Szeredi * 4572fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4573fd4a0edfSMiklos Szeredi * 4574fd4a0edfSMiklos Szeredi * Does not call security hook. 4575fd4a0edfSMiklos Szeredi */ 4576fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4577fd4a0edfSMiklos Szeredi { 4578fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4579f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4580f2df5da6SAl Viro const char *link; 4581f2df5da6SAl Viro int res; 4582fd4a0edfSMiklos Szeredi 458376fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 458476fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 458576fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 458676fca90eSMiklos Szeredi 458776fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4588fd4a0edfSMiklos Szeredi return -EINVAL; 4589fd4a0edfSMiklos Szeredi 459076fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 459176fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 459276fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 459376fca90eSMiklos Szeredi } 459476fca90eSMiklos Szeredi 45954c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4596f2df5da6SAl Viro if (!link) { 4597f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4598f2df5da6SAl Viro if (IS_ERR(link)) 4599f2df5da6SAl Viro return PTR_ERR(link); 4600f2df5da6SAl Viro } 4601f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4602f2df5da6SAl Viro do_delayed_call(&done); 4603f2df5da6SAl Viro return res; 4604fd4a0edfSMiklos Szeredi } 4605fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46061da177e4SLinus Torvalds 4607d60874cdSMiklos Szeredi /** 4608d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4609d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4610d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4611d60874cdSMiklos Szeredi * 4612d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4613d60874cdSMiklos Szeredi * 4614d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4615d60874cdSMiklos Szeredi * 4616d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4617d60874cdSMiklos Szeredi */ 4618d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4619d60874cdSMiklos Szeredi { 4620d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4621d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4622d60874cdSMiklos Szeredi 4623d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4624d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4625d60874cdSMiklos Szeredi if (!res) 4626d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4627d60874cdSMiklos Szeredi } 4628d60874cdSMiklos Szeredi return res; 4629d60874cdSMiklos Szeredi } 4630d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4631d60874cdSMiklos Szeredi 46321da177e4SLinus Torvalds /* get the link contents into pagecache */ 46336b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4634fceef393SAl Viro struct delayed_call *callback) 46351da177e4SLinus Torvalds { 4636ebd09abbSDuane Griffin char *kaddr; 46371da177e4SLinus Torvalds struct page *page; 46386b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46396b255391SAl Viro 4640d3883d4fSAl Viro if (!dentry) { 4641d3883d4fSAl Viro page = find_get_page(mapping, 0); 4642d3883d4fSAl Viro if (!page) 46436b255391SAl Viro return ERR_PTR(-ECHILD); 4644d3883d4fSAl Viro if (!PageUptodate(page)) { 4645d3883d4fSAl Viro put_page(page); 4646d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4647d3883d4fSAl Viro } 4648d3883d4fSAl Viro } else { 4649090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46501da177e4SLinus Torvalds if (IS_ERR(page)) 46516fe6900eSNick Piggin return (char*)page; 4652d3883d4fSAl Viro } 4653fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 465421fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 465521fc61c7SAl Viro kaddr = page_address(page); 46566b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4657ebd09abbSDuane Griffin return kaddr; 46581da177e4SLinus Torvalds } 46591da177e4SLinus Torvalds 46606b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46611da177e4SLinus Torvalds 4662fceef393SAl Viro void page_put_link(void *arg) 46631da177e4SLinus Torvalds { 4664fceef393SAl Viro put_page(arg); 46651da177e4SLinus Torvalds } 46664d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46671da177e4SLinus Torvalds 4668aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4669aa80deabSAl Viro { 4670fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46716b255391SAl Viro int res = readlink_copy(buffer, buflen, 46726b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4673fceef393SAl Viro &done)); 4674fceef393SAl Viro do_delayed_call(&done); 4675aa80deabSAl Viro return res; 4676aa80deabSAl Viro } 4677aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4678aa80deabSAl Viro 467954566b2cSNick Piggin /* 468054566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 468154566b2cSNick Piggin */ 468254566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46831da177e4SLinus Torvalds { 46841da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46850adb25d2SKirill Korotaev struct page *page; 4686afddba49SNick Piggin void *fsdata; 4687beb497abSDmitriy Monakhov int err; 4688c718a975STetsuo Handa unsigned int flags = 0; 468954566b2cSNick Piggin if (nofs) 469054566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46911da177e4SLinus Torvalds 46927e53cac4SNeilBrown retry: 4693afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 469454566b2cSNick Piggin flags, &page, &fsdata); 46951da177e4SLinus Torvalds if (err) 4696afddba49SNick Piggin goto fail; 4697afddba49SNick Piggin 469821fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4699afddba49SNick Piggin 4700afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4701afddba49SNick Piggin page, fsdata); 47021da177e4SLinus Torvalds if (err < 0) 47031da177e4SLinus Torvalds goto fail; 4704afddba49SNick Piggin if (err < len-1) 4705afddba49SNick Piggin goto retry; 4706afddba49SNick Piggin 47071da177e4SLinus Torvalds mark_inode_dirty(inode); 47081da177e4SLinus Torvalds return 0; 47091da177e4SLinus Torvalds fail: 47101da177e4SLinus Torvalds return err; 47111da177e4SLinus Torvalds } 47124d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47131da177e4SLinus Torvalds 47140adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47150adb25d2SKirill Korotaev { 47160adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4717c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47180adb25d2SKirill Korotaev } 47194d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47200adb25d2SKirill Korotaev 472192e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47226b255391SAl Viro .get_link = page_get_link, 47231da177e4SLinus Torvalds }; 47241da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4725