1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 4949883d185SAl Viro unsigned seq, m_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 506fceef393SAl Viro struct inode *link_inode; 5079883d185SAl Viro unsigned root_seq; 5089883d185SAl Viro int dfd; 5093859a271SKees Cook } __randomize_layout; 5101f55a6ecSAl Viro 5119883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 512894bc8c4SAl Viro { 513756daf26SNeilBrown struct nameidata *old = current->nameidata; 514756daf26SNeilBrown p->stack = p->internal; 515c8a53ee5SAl Viro p->dfd = dfd; 516c8a53ee5SAl Viro p->name = name; 517756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5189883d185SAl Viro p->saved = old; 519756daf26SNeilBrown current->nameidata = p; 520894bc8c4SAl Viro } 521894bc8c4SAl Viro 5229883d185SAl Viro static void restore_nameidata(void) 523894bc8c4SAl Viro { 5249883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 525756daf26SNeilBrown 526756daf26SNeilBrown current->nameidata = old; 527756daf26SNeilBrown if (old) 528756daf26SNeilBrown old->total_link_count = now->total_link_count; 529e1a63bbcSAl Viro if (now->stack != now->internal) 530756daf26SNeilBrown kfree(now->stack); 531894bc8c4SAl Viro } 532894bc8c4SAl Viro 533894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 534894bc8c4SAl Viro { 535bc40aee0SAl Viro struct saved *p; 536bc40aee0SAl Viro 537bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 538bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 539bc40aee0SAl Viro GFP_ATOMIC); 540bc40aee0SAl Viro if (unlikely(!p)) 541bc40aee0SAl Viro return -ECHILD; 542bc40aee0SAl Viro } else { 543bc40aee0SAl Viro p= kmalloc(MAXSYMLINKS * sizeof(struct saved), 544894bc8c4SAl Viro GFP_KERNEL); 545894bc8c4SAl Viro if (unlikely(!p)) 546894bc8c4SAl Viro return -ENOMEM; 547bc40aee0SAl Viro } 548894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 549894bc8c4SAl Viro nd->stack = p; 550894bc8c4SAl Viro return 0; 551894bc8c4SAl Viro } 552894bc8c4SAl Viro 553397d425dSEric W. Biederman /** 554397d425dSEric W. Biederman * path_connected - Verify that a path->dentry is below path->mnt.mnt_root 555397d425dSEric W. Biederman * @path: nameidate to verify 556397d425dSEric W. Biederman * 557397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 558397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 559397d425dSEric W. Biederman */ 560397d425dSEric W. Biederman static bool path_connected(const struct path *path) 561397d425dSEric W. Biederman { 562397d425dSEric W. Biederman struct vfsmount *mnt = path->mnt; 563397d425dSEric W. Biederman 564397d425dSEric W. Biederman /* Only bind mounts can have disconnected paths */ 565397d425dSEric W. Biederman if (mnt->mnt_root == mnt->mnt_sb->s_root) 566397d425dSEric W. Biederman return true; 567397d425dSEric W. Biederman 568397d425dSEric W. Biederman return is_subdir(path->dentry, mnt->mnt_root); 569397d425dSEric W. Biederman } 570397d425dSEric W. Biederman 571894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 572894bc8c4SAl Viro { 573da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 574894bc8c4SAl Viro return 0; 575894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 576894bc8c4SAl Viro return 0; 577894bc8c4SAl Viro return __nd_alloc_stack(nd); 578894bc8c4SAl Viro } 579894bc8c4SAl Viro 5807973387aSAl Viro static void drop_links(struct nameidata *nd) 5817973387aSAl Viro { 5827973387aSAl Viro int i = nd->depth; 5837973387aSAl Viro while (i--) { 5847973387aSAl Viro struct saved *last = nd->stack + i; 585fceef393SAl Viro do_delayed_call(&last->done); 586fceef393SAl Viro clear_delayed_call(&last->done); 5877973387aSAl Viro } 5887973387aSAl Viro } 5897973387aSAl Viro 5907973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5917973387aSAl Viro { 5927973387aSAl Viro drop_links(nd); 5937973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5947973387aSAl Viro int i; 5957973387aSAl Viro path_put(&nd->path); 5967973387aSAl Viro for (i = 0; i < nd->depth; i++) 5977973387aSAl Viro path_put(&nd->stack[i].link); 598102b8af2SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 599102b8af2SAl Viro path_put(&nd->root); 600102b8af2SAl Viro nd->root.mnt = NULL; 601102b8af2SAl Viro } 6027973387aSAl Viro } else { 6037973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6047973387aSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6057973387aSAl Viro nd->root.mnt = NULL; 6067973387aSAl Viro rcu_read_unlock(); 6077973387aSAl Viro } 6087973387aSAl Viro nd->depth = 0; 6097973387aSAl Viro } 6107973387aSAl Viro 6117973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6127973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6137973387aSAl Viro struct path *path, unsigned seq) 6147973387aSAl Viro { 6157973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6167973387aSAl Viro if (unlikely(res)) { 6177973387aSAl Viro if (res > 0) 6187973387aSAl Viro path->mnt = NULL; 6197973387aSAl Viro path->dentry = NULL; 6207973387aSAl Viro return false; 6217973387aSAl Viro } 6227973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6237973387aSAl Viro path->dentry = NULL; 6247973387aSAl Viro return false; 6257973387aSAl Viro } 6267973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6277973387aSAl Viro } 6287973387aSAl Viro 6297973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6307973387aSAl Viro { 6317973387aSAl Viro int i; 6327973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6337973387aSAl Viro struct saved *last = nd->stack + i; 6347973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6357973387aSAl Viro drop_links(nd); 6367973387aSAl Viro nd->depth = i + 1; 6377973387aSAl Viro return false; 6387973387aSAl Viro } 6397973387aSAl Viro } 6407973387aSAl Viro return true; 6417973387aSAl Viro } 6427973387aSAl Viro 64319660af7SAl Viro /* 64431e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 64519660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 64619660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 64757e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 64819660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 64919660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 65019660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 65119660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 65231e6b01fSNick Piggin */ 65331e6b01fSNick Piggin 65431e6b01fSNick Piggin /** 65519660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 65619660af7SAl Viro * @nd: nameidata pathwalk data 65739191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 65831e6b01fSNick Piggin * 6594675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6604675ac39SAl Viro * for ref-walk mode. 6614675ac39SAl Viro * Must be called from rcu-walk context. 6627973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6637973387aSAl Viro * terminate_walk(). 66431e6b01fSNick Piggin */ 6654675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 66631e6b01fSNick Piggin { 66731e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 66831e6b01fSNick Piggin 66931e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 670e5c832d5SLinus Torvalds 671e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6727973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6737973387aSAl Viro goto out2; 6744675ac39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 6754675ac39SAl Viro goto out1; 6764675ac39SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 6774675ac39SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) 6784675ac39SAl Viro goto out; 6794675ac39SAl Viro } 6804675ac39SAl Viro rcu_read_unlock(); 6814675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6824675ac39SAl Viro return 0; 6834675ac39SAl Viro 6844675ac39SAl Viro out2: 6854675ac39SAl Viro nd->path.mnt = NULL; 6864675ac39SAl Viro nd->path.dentry = NULL; 6874675ac39SAl Viro out1: 6884675ac39SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6894675ac39SAl Viro nd->root.mnt = NULL; 6904675ac39SAl Viro out: 6914675ac39SAl Viro rcu_read_unlock(); 6924675ac39SAl Viro return -ECHILD; 6934675ac39SAl Viro } 6944675ac39SAl Viro 6954675ac39SAl Viro /** 6964675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 6974675ac39SAl Viro * @nd: nameidata pathwalk data 6984675ac39SAl Viro * @dentry: child of nd->path.dentry 6994675ac39SAl Viro * @seq: seq number to check dentry against 7004675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7014675ac39SAl Viro * 7024675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7034675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7044675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7054675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7064675ac39SAl Viro * terminate_walk(). 7074675ac39SAl Viro */ 7084675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7094675ac39SAl Viro { 7104675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7114675ac39SAl Viro 7124675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7134675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7144675ac39SAl Viro goto out2; 7157973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7167973387aSAl Viro goto out2; 7174675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7187973387aSAl Viro goto out1; 71948a066e7SAl Viro 72015570086SLinus Torvalds /* 7214675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7224675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7234675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7244675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7254675ac39SAl Viro * know the parent must still be valid if the child sequence number is 72615570086SLinus Torvalds */ 7274675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 728e5c832d5SLinus Torvalds goto out; 7294675ac39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) { 7304675ac39SAl Viro rcu_read_unlock(); 7314675ac39SAl Viro dput(dentry); 7324675ac39SAl Viro goto drop_root_mnt; 73319660af7SAl Viro } 734e5c832d5SLinus Torvalds /* 735e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 736e5c832d5SLinus Torvalds * still valid and get it if required. 737e5c832d5SLinus Torvalds */ 738e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 7395a8d87e8SAl Viro if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { 7405a8d87e8SAl Viro rcu_read_unlock(); 7415a8d87e8SAl Viro dput(dentry); 7425a8d87e8SAl Viro return -ECHILD; 7437973387aSAl Viro } 74431e6b01fSNick Piggin } 74531e6b01fSNick Piggin 7468b61e74fSAl Viro rcu_read_unlock(); 74731e6b01fSNick Piggin return 0; 74819660af7SAl Viro 7497973387aSAl Viro out2: 7507973387aSAl Viro nd->path.mnt = NULL; 7517973387aSAl Viro out1: 7527973387aSAl Viro nd->path.dentry = NULL; 753e5c832d5SLinus Torvalds out: 7548b61e74fSAl Viro rcu_read_unlock(); 755d0d27277SLinus Torvalds drop_root_mnt: 756d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 757d0d27277SLinus Torvalds nd->root.mnt = NULL; 75831e6b01fSNick Piggin return -ECHILD; 75931e6b01fSNick Piggin } 76031e6b01fSNick Piggin 7614ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76234286d66SNick Piggin { 763a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7644ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 765a89f8337SAl Viro else 766a89f8337SAl Viro return 1; 76734286d66SNick Piggin } 76834286d66SNick Piggin 7699f1fafeeSAl Viro /** 7709f1fafeeSAl Viro * complete_walk - successful completion of path walk 7719f1fafeeSAl Viro * @nd: pointer nameidata 77239159de2SJeff Layton * 7739f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7749f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7759f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7769f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7779f1fafeeSAl Viro * need to drop nd->path. 77839159de2SJeff Layton */ 7799f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78039159de2SJeff Layton { 78116c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78239159de2SJeff Layton int status; 78339159de2SJeff Layton 7849f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 7859f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 7869f1fafeeSAl Viro nd->root.mnt = NULL; 7874675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 78848a066e7SAl Viro return -ECHILD; 78948a066e7SAl Viro } 7909f1fafeeSAl Viro 79116c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 79239159de2SJeff Layton return 0; 79339159de2SJeff Layton 794ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 79516c2cd71SAl Viro return 0; 79616c2cd71SAl Viro 797ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 79839159de2SJeff Layton if (status > 0) 79939159de2SJeff Layton return 0; 80039159de2SJeff Layton 80116c2cd71SAl Viro if (!status) 80239159de2SJeff Layton status = -ESTALE; 80316c2cd71SAl Viro 80439159de2SJeff Layton return status; 80539159de2SJeff Layton } 80639159de2SJeff Layton 80718d8c860SAl Viro static void set_root(struct nameidata *nd) 8082a737871SAl Viro { 80931e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8109e6697e2SAl Viro 8119e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8128f47a016SAl Viro unsigned seq; 813c28cc364SNick Piggin 814c28cc364SNick Piggin do { 815c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 81631e6b01fSNick Piggin nd->root = fs->root; 8178f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 818c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8199e6697e2SAl Viro } else { 8209e6697e2SAl Viro get_fs_root(fs, &nd->root); 8219e6697e2SAl Viro } 82231e6b01fSNick Piggin } 82331e6b01fSNick Piggin 8241d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 825051d3812SIan Kent { 826051d3812SIan Kent dput(path->dentry); 8274ac91378SJan Blunck if (path->mnt != nd->path.mnt) 828051d3812SIan Kent mntput(path->mnt); 829051d3812SIan Kent } 830051d3812SIan Kent 8317b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8327b9337aaSNick Piggin struct nameidata *nd) 833051d3812SIan Kent { 83431e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8354ac91378SJan Blunck dput(nd->path.dentry); 83631e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8374ac91378SJan Blunck mntput(nd->path.mnt); 8389a229683SHuang Shijie } 83931e6b01fSNick Piggin nd->path.mnt = path->mnt; 8404ac91378SJan Blunck nd->path.dentry = path->dentry; 841051d3812SIan Kent } 842051d3812SIan Kent 843248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 844248fb5b9SAl Viro { 845248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 846248fb5b9SAl Viro struct dentry *d; 847248fb5b9SAl Viro nd->path = nd->root; 848248fb5b9SAl Viro d = nd->path.dentry; 849248fb5b9SAl Viro nd->inode = d->d_inode; 850248fb5b9SAl Viro nd->seq = nd->root_seq; 851248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 852248fb5b9SAl Viro return -ECHILD; 853248fb5b9SAl Viro } else { 854248fb5b9SAl Viro path_put(&nd->path); 855248fb5b9SAl Viro nd->path = nd->root; 856248fb5b9SAl Viro path_get(&nd->path); 857248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 858248fb5b9SAl Viro } 859248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 860248fb5b9SAl Viro return 0; 861248fb5b9SAl Viro } 862248fb5b9SAl Viro 863b5fb63c1SChristoph Hellwig /* 8646b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 865b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 866b5fb63c1SChristoph Hellwig */ 8676e77137bSAl Viro void nd_jump_link(struct path *path) 868b5fb63c1SChristoph Hellwig { 8696e77137bSAl Viro struct nameidata *nd = current->nameidata; 870b5fb63c1SChristoph Hellwig path_put(&nd->path); 871b5fb63c1SChristoph Hellwig 872b5fb63c1SChristoph Hellwig nd->path = *path; 873b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 874b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 875b5fb63c1SChristoph Hellwig } 876b5fb63c1SChristoph Hellwig 877b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 878574197e0SAl Viro { 87921c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 880fceef393SAl Viro do_delayed_call(&last->done); 8816548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 882b9ff4429SAl Viro path_put(&last->link); 883574197e0SAl Viro } 884574197e0SAl Viro 885561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 886561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 887800179c9SKees Cook 888800179c9SKees Cook /** 889800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 89055852635SRandy Dunlap * @nd: nameidata pathwalk data 891800179c9SKees Cook * 892800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 893800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 894800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 895800179c9SKees Cook * processes from failing races against path names that may change out 896800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 897800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 898800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 899800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 900800179c9SKees Cook * 901800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 902800179c9SKees Cook */ 903fec2fa24SAl Viro static inline int may_follow_link(struct nameidata *nd) 904800179c9SKees Cook { 905800179c9SKees Cook const struct inode *inode; 906800179c9SKees Cook const struct inode *parent; 9072d7f9e2aSSeth Forshee kuid_t puid; 908800179c9SKees Cook 909800179c9SKees Cook if (!sysctl_protected_symlinks) 910800179c9SKees Cook return 0; 911800179c9SKees Cook 912800179c9SKees Cook /* Allowed if owner and follower match. */ 913fceef393SAl Viro inode = nd->link_inode; 91481abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 915800179c9SKees Cook return 0; 916800179c9SKees Cook 917800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 918aa65fa35SAl Viro parent = nd->inode; 919800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 920800179c9SKees Cook return 0; 921800179c9SKees Cook 922800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9232d7f9e2aSSeth Forshee puid = parent->i_uid; 9242d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 925800179c9SKees Cook return 0; 926800179c9SKees Cook 92731956502SAl Viro if (nd->flags & LOOKUP_RCU) 92831956502SAl Viro return -ECHILD; 92931956502SAl Viro 9301cf2665bSAl Viro audit_log_link_denied("follow_link", &nd->stack[0].link); 931800179c9SKees Cook return -EACCES; 932800179c9SKees Cook } 933800179c9SKees Cook 934800179c9SKees Cook /** 935800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 936800179c9SKees Cook * @inode: the source inode to hardlink from 937800179c9SKees Cook * 938800179c9SKees Cook * Return false if at least one of the following conditions: 939800179c9SKees Cook * - inode is not a regular file 940800179c9SKees Cook * - inode is setuid 941800179c9SKees Cook * - inode is setgid and group-exec 942800179c9SKees Cook * - access failure for read and write 943800179c9SKees Cook * 944800179c9SKees Cook * Otherwise returns true. 945800179c9SKees Cook */ 946800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 947800179c9SKees Cook { 948800179c9SKees Cook umode_t mode = inode->i_mode; 949800179c9SKees Cook 950800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 951800179c9SKees Cook if (!S_ISREG(mode)) 952800179c9SKees Cook return false; 953800179c9SKees Cook 954800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 955800179c9SKees Cook if (mode & S_ISUID) 956800179c9SKees Cook return false; 957800179c9SKees Cook 958800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 959800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 960800179c9SKees Cook return false; 961800179c9SKees Cook 962800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 963800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 964800179c9SKees Cook return false; 965800179c9SKees Cook 966800179c9SKees Cook return true; 967800179c9SKees Cook } 968800179c9SKees Cook 969800179c9SKees Cook /** 970800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 971800179c9SKees Cook * @link: the source to hardlink from 972800179c9SKees Cook * 973800179c9SKees Cook * Block hardlink when all of: 974800179c9SKees Cook * - sysctl_protected_hardlinks enabled 975800179c9SKees Cook * - fsuid does not match inode 976800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 977f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 978800179c9SKees Cook * 979800179c9SKees Cook * Returns 0 if successful, -ve on error. 980800179c9SKees Cook */ 981800179c9SKees Cook static int may_linkat(struct path *link) 982800179c9SKees Cook { 983800179c9SKees Cook struct inode *inode; 984800179c9SKees Cook 985800179c9SKees Cook if (!sysctl_protected_hardlinks) 986800179c9SKees Cook return 0; 987800179c9SKees Cook 988800179c9SKees Cook inode = link->dentry->d_inode; 989800179c9SKees Cook 990800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 991800179c9SKees Cook * otherwise, it must be a safe source. 992800179c9SKees Cook */ 993cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 994800179c9SKees Cook return 0; 995800179c9SKees Cook 996a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 997800179c9SKees Cook return -EPERM; 998800179c9SKees Cook } 999800179c9SKees Cook 10003b2e7f75SAl Viro static __always_inline 10013b2e7f75SAl Viro const char *get_link(struct nameidata *nd) 10021da177e4SLinus Torvalds { 1003ab104923SAl Viro struct saved *last = nd->stack + nd->depth - 1; 10041cf2665bSAl Viro struct dentry *dentry = last->link.dentry; 1005fceef393SAl Viro struct inode *inode = nd->link_inode; 10066d7b5aaeSAl Viro int error; 10070a959df5SAl Viro const char *res; 10081da177e4SLinus Torvalds 10098fa9dd24SNeilBrown if (!(nd->flags & LOOKUP_RCU)) { 10108fa9dd24SNeilBrown touch_atime(&last->link); 10118fa9dd24SNeilBrown cond_resched(); 1012598e3c8fSMiklos Szeredi } else if (atime_needs_update_rcu(&last->link, inode)) { 10134675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10148fa9dd24SNeilBrown return ERR_PTR(-ECHILD); 10158fa9dd24SNeilBrown touch_atime(&last->link); 10168fa9dd24SNeilBrown } 10178fa9dd24SNeilBrown 1018bda0be7aSNeilBrown error = security_inode_follow_link(dentry, inode, 1019bda0be7aSNeilBrown nd->flags & LOOKUP_RCU); 1020bda0be7aSNeilBrown if (unlikely(error)) 10216920a440SAl Viro return ERR_PTR(error); 102236f3b4f6SAl Viro 102386acdca1SAl Viro nd->last_type = LAST_BIND; 1024d4dee48bSAl Viro res = inode->i_link; 1025d4dee48bSAl Viro if (!res) { 1026fceef393SAl Viro const char * (*get)(struct dentry *, struct inode *, 1027fceef393SAl Viro struct delayed_call *); 1028fceef393SAl Viro get = inode->i_op->get_link; 10298c1b4566SAl Viro if (nd->flags & LOOKUP_RCU) { 1030fceef393SAl Viro res = get(NULL, inode, &last->done); 10316b255391SAl Viro if (res == ERR_PTR(-ECHILD)) { 10324675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 10338c1b4566SAl Viro return ERR_PTR(-ECHILD); 1034fceef393SAl Viro res = get(dentry, inode, &last->done); 10358c1b4566SAl Viro } 10366b255391SAl Viro } else { 1037fceef393SAl Viro res = get(dentry, inode, &last->done); 10386b255391SAl Viro } 1039fceef393SAl Viro if (IS_ERR_OR_NULL(res)) 1040fab51e8aSAl Viro return res; 10410a959df5SAl Viro } 1042fab51e8aSAl Viro if (*res == '/') { 1043fab51e8aSAl Viro if (!nd->root.mnt) 1044fab51e8aSAl Viro set_root(nd); 1045248fb5b9SAl Viro if (unlikely(nd_jump_root(nd))) 1046fab51e8aSAl Viro return ERR_PTR(-ECHILD); 1047fab51e8aSAl Viro while (unlikely(*++res == '/')) 1048fab51e8aSAl Viro ; 1049fab51e8aSAl Viro } 1050fab51e8aSAl Viro if (!*res) 1051fab51e8aSAl Viro res = NULL; 10520a959df5SAl Viro return res; 10530a959df5SAl Viro } 10546d7b5aaeSAl Viro 1055f015f126SDavid Howells /* 1056f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1057f015f126SDavid Howells * 1058f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1059f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1060f015f126SDavid Howells * Up is towards /. 1061f015f126SDavid Howells * 1062f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1063f015f126SDavid Howells * root. 1064f015f126SDavid Howells */ 1065bab77ebfSAl Viro int follow_up(struct path *path) 10661da177e4SLinus Torvalds { 10670714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 10680714a533SAl Viro struct mount *parent; 10691da177e4SLinus Torvalds struct dentry *mountpoint; 107099b7db7bSNick Piggin 107148a066e7SAl Viro read_seqlock_excl(&mount_lock); 10720714a533SAl Viro parent = mnt->mnt_parent; 10733c0a6163SAl Viro if (parent == mnt) { 107448a066e7SAl Viro read_sequnlock_excl(&mount_lock); 10751da177e4SLinus Torvalds return 0; 10761da177e4SLinus Torvalds } 10770714a533SAl Viro mntget(&parent->mnt); 1078a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 107948a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1080bab77ebfSAl Viro dput(path->dentry); 1081bab77ebfSAl Viro path->dentry = mountpoint; 1082bab77ebfSAl Viro mntput(path->mnt); 10830714a533SAl Viro path->mnt = &parent->mnt; 10841da177e4SLinus Torvalds return 1; 10851da177e4SLinus Torvalds } 10864d359507SAl Viro EXPORT_SYMBOL(follow_up); 10871da177e4SLinus Torvalds 1088b5c84bf6SNick Piggin /* 10899875cf80SDavid Howells * Perform an automount 10909875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 10919875cf80SDavid Howells * were called with. 10921da177e4SLinus Torvalds */ 1093756daf26SNeilBrown static int follow_automount(struct path *path, struct nameidata *nd, 10949875cf80SDavid Howells bool *need_mntput) 109531e6b01fSNick Piggin { 10969875cf80SDavid Howells struct vfsmount *mnt; 1097ea5b778aSDavid Howells int err; 10989875cf80SDavid Howells 10999875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 11009875cf80SDavid Howells return -EREMOTE; 11019875cf80SDavid Howells 11020ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11030ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11040ec26fd0SMiklos Szeredi * the name. 11050ec26fd0SMiklos Szeredi * 11060ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11075a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11080ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11090ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11100ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11110ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11125a30d8a2SDavid Howells */ 1113756daf26SNeilBrown if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11145d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 11155d38f049SIan Kent path->dentry->d_inode) 11169875cf80SDavid Howells return -EISDIR; 11170ec26fd0SMiklos Szeredi 1118756daf26SNeilBrown nd->total_link_count++; 1119756daf26SNeilBrown if (nd->total_link_count >= 40) 11209875cf80SDavid Howells return -ELOOP; 11219875cf80SDavid Howells 11229875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 11239875cf80SDavid Howells if (IS_ERR(mnt)) { 11249875cf80SDavid Howells /* 11259875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 11269875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 11279875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 11289875cf80SDavid Howells * 11299875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 11309875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 11319875cf80SDavid Howells * the path is inaccessible and we should say so. 11329875cf80SDavid Howells */ 1133756daf26SNeilBrown if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) 11349875cf80SDavid Howells return -EREMOTE; 11359875cf80SDavid Howells return PTR_ERR(mnt); 113631e6b01fSNick Piggin } 1137ea5b778aSDavid Howells 11389875cf80SDavid Howells if (!mnt) /* mount collision */ 11399875cf80SDavid Howells return 0; 11409875cf80SDavid Howells 11418aef1884SAl Viro if (!*need_mntput) { 11428aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 11438aef1884SAl Viro mntget(path->mnt); 11448aef1884SAl Viro *need_mntput = true; 11458aef1884SAl Viro } 114619a167afSAl Viro err = finish_automount(mnt, path); 1147ea5b778aSDavid Howells 1148ea5b778aSDavid Howells switch (err) { 1149ea5b778aSDavid Howells case -EBUSY: 1150ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 115119a167afSAl Viro return 0; 1152ea5b778aSDavid Howells case 0: 11538aef1884SAl Viro path_put(path); 11549875cf80SDavid Howells path->mnt = mnt; 11559875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 11569875cf80SDavid Howells return 0; 115719a167afSAl Viro default: 115819a167afSAl Viro return err; 11599875cf80SDavid Howells } 116019a167afSAl Viro 1161ea5b778aSDavid Howells } 11629875cf80SDavid Howells 11639875cf80SDavid Howells /* 11649875cf80SDavid Howells * Handle a dentry that is managed in some way. 1165cc53ce53SDavid Howells * - Flagged for transit management (autofs) 11669875cf80SDavid Howells * - Flagged as mountpoint 11679875cf80SDavid Howells * - Flagged as automount point 11689875cf80SDavid Howells * 11699875cf80SDavid Howells * This may only be called in refwalk mode. 11709875cf80SDavid Howells * 11719875cf80SDavid Howells * Serialization is taken care of in namespace.c 11729875cf80SDavid Howells */ 1173756daf26SNeilBrown static int follow_managed(struct path *path, struct nameidata *nd) 11749875cf80SDavid Howells { 11758aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 11769875cf80SDavid Howells unsigned managed; 11779875cf80SDavid Howells bool need_mntput = false; 11788aef1884SAl Viro int ret = 0; 11799875cf80SDavid Howells 11809875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 11819875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 11829875cf80SDavid Howells * the components of that value change under us */ 11836aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 11849875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 11859875cf80SDavid Howells unlikely(managed != 0)) { 1186cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1187cc53ce53SDavid Howells * being held. */ 1188cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1189cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1190cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1191fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1192cc53ce53SDavid Howells if (ret < 0) 11938aef1884SAl Viro break; 1194cc53ce53SDavid Howells } 1195cc53ce53SDavid Howells 11969875cf80SDavid Howells /* Transit to a mounted filesystem. */ 11979875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 11989875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11999875cf80SDavid Howells if (mounted) { 12009875cf80SDavid Howells dput(path->dentry); 12019875cf80SDavid Howells if (need_mntput) 1202463ffb2eSAl Viro mntput(path->mnt); 1203463ffb2eSAl Viro path->mnt = mounted; 1204463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12059875cf80SDavid Howells need_mntput = true; 12069875cf80SDavid Howells continue; 1207463ffb2eSAl Viro } 1208463ffb2eSAl Viro 12099875cf80SDavid Howells /* Something is mounted on this dentry in another 12109875cf80SDavid Howells * namespace and/or whatever was mounted there in this 121148a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 121248a066e7SAl Viro * get it */ 12131da177e4SLinus Torvalds } 12149875cf80SDavid Howells 12159875cf80SDavid Howells /* Handle an automount point */ 12169875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 1217756daf26SNeilBrown ret = follow_automount(path, nd, &need_mntput); 12189875cf80SDavid Howells if (ret < 0) 12198aef1884SAl Viro break; 12209875cf80SDavid Howells continue; 12219875cf80SDavid Howells } 12229875cf80SDavid Howells 12239875cf80SDavid Howells /* We didn't change the current path point */ 12249875cf80SDavid Howells break; 12259875cf80SDavid Howells } 12268aef1884SAl Viro 12278aef1884SAl Viro if (need_mntput && path->mnt == mnt) 12288aef1884SAl Viro mntput(path->mnt); 1229e9742b53SAl Viro if (ret == -EISDIR || !ret) 1230e9742b53SAl Viro ret = 1; 12318402752eSAl Viro if (need_mntput) 12328402752eSAl Viro nd->flags |= LOOKUP_JUMPED; 12338402752eSAl Viro if (unlikely(ret < 0)) 12348402752eSAl Viro path_put_conditional(path, nd); 12358402752eSAl Viro return ret; 12361da177e4SLinus Torvalds } 12371da177e4SLinus Torvalds 1238cc53ce53SDavid Howells int follow_down_one(struct path *path) 12391da177e4SLinus Torvalds { 12401da177e4SLinus Torvalds struct vfsmount *mounted; 12411da177e4SLinus Torvalds 12421c755af4SAl Viro mounted = lookup_mnt(path); 12431da177e4SLinus Torvalds if (mounted) { 12449393bd07SAl Viro dput(path->dentry); 12459393bd07SAl Viro mntput(path->mnt); 12469393bd07SAl Viro path->mnt = mounted; 12479393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12481da177e4SLinus Torvalds return 1; 12491da177e4SLinus Torvalds } 12501da177e4SLinus Torvalds return 0; 12511da177e4SLinus Torvalds } 12524d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12531da177e4SLinus Torvalds 1254fb5f51c7SIan Kent static inline int managed_dentry_rcu(const struct path *path) 125562a7375eSIan Kent { 1256fb5f51c7SIan Kent return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1257fb5f51c7SIan Kent path->dentry->d_op->d_manage(path, true) : 0; 125862a7375eSIan Kent } 125962a7375eSIan Kent 12609875cf80SDavid Howells /* 1261287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1262287548e4SAl Viro * we meet a managed dentry that would need blocking. 12639875cf80SDavid Howells */ 12649875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1265254cf582SAl Viro struct inode **inode, unsigned *seqp) 12669875cf80SDavid Howells { 126762a7375eSIan Kent for (;;) { 1268c7105365SAl Viro struct mount *mounted; 126962a7375eSIan Kent /* 127062a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 127162a7375eSIan Kent * that wants to block transit. 127262a7375eSIan Kent */ 1273fb5f51c7SIan Kent switch (managed_dentry_rcu(path)) { 1274b8faf035SNeilBrown case -ECHILD: 1275b8faf035SNeilBrown default: 1276ab90911fSDavid Howells return false; 1277b8faf035SNeilBrown case -EISDIR: 1278b8faf035SNeilBrown return true; 1279b8faf035SNeilBrown case 0: 1280b8faf035SNeilBrown break; 1281b8faf035SNeilBrown } 128262a7375eSIan Kent 128362a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1284b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 128562a7375eSIan Kent 1286474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 12879875cf80SDavid Howells if (!mounted) 12889875cf80SDavid Howells break; 1289c7105365SAl Viro path->mnt = &mounted->mnt; 1290c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1291a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1292254cf582SAl Viro *seqp = read_seqcount_begin(&path->dentry->d_seq); 129359430262SLinus Torvalds /* 129459430262SLinus Torvalds * Update the inode too. We don't need to re-check the 129559430262SLinus Torvalds * dentry sequence number here after this d_inode read, 129659430262SLinus Torvalds * because a mount-point is always pinned. 129759430262SLinus Torvalds */ 129859430262SLinus Torvalds *inode = path->dentry->d_inode; 12999875cf80SDavid Howells } 1300f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1301b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1302287548e4SAl Viro } 1303287548e4SAl Viro 130431e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 130531e6b01fSNick Piggin { 13064023bfc9SAl Viro struct inode *inode = nd->inode; 130731e6b01fSNick Piggin 130831e6b01fSNick Piggin while (1) { 1309aed434adSAl Viro if (path_equal(&nd->path, &nd->root)) 131031e6b01fSNick Piggin break; 131131e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 131231e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 131331e6b01fSNick Piggin struct dentry *parent = old->d_parent; 131431e6b01fSNick Piggin unsigned seq; 131531e6b01fSNick Piggin 13164023bfc9SAl Viro inode = parent->d_inode; 131731e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1318aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1319aed434adSAl Viro return -ECHILD; 132031e6b01fSNick Piggin nd->path.dentry = parent; 132131e6b01fSNick Piggin nd->seq = seq; 1322397d425dSEric W. Biederman if (unlikely(!path_connected(&nd->path))) 1323397d425dSEric W. Biederman return -ENOENT; 132431e6b01fSNick Piggin break; 1325aed434adSAl Viro } else { 1326aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1327aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1328aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1329aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1330aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1331aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1332aed434adSAl Viro return -ECHILD; 1333aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 133431e6b01fSNick Piggin break; 1335aed434adSAl Viro /* we know that mountpoint was pinned */ 1336aed434adSAl Viro nd->path.dentry = mountpoint; 1337aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1338aed434adSAl Viro inode = inode2; 1339aed434adSAl Viro nd->seq = seq; 134031e6b01fSNick Piggin } 1341aed434adSAl Viro } 1342aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1343b37199e6SAl Viro struct mount *mounted; 1344b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1345aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1346aed434adSAl Viro return -ECHILD; 1347b37199e6SAl Viro if (!mounted) 1348b37199e6SAl Viro break; 1349b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1350b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 13514023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1352b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1353b37199e6SAl Viro } 13544023bfc9SAl Viro nd->inode = inode; 135531e6b01fSNick Piggin return 0; 135631e6b01fSNick Piggin } 135731e6b01fSNick Piggin 13589875cf80SDavid Howells /* 1359cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1360cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1361cc53ce53SDavid Howells * caller is permitted to proceed or not. 1362cc53ce53SDavid Howells */ 13637cc90cc3SAl Viro int follow_down(struct path *path) 1364cc53ce53SDavid Howells { 1365cc53ce53SDavid Howells unsigned managed; 1366cc53ce53SDavid Howells int ret; 1367cc53ce53SDavid Howells 13686aa7de05SMark Rutland while (managed = READ_ONCE(path->dentry->d_flags), 1369cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1370cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1371cc53ce53SDavid Howells * being held. 1372cc53ce53SDavid Howells * 1373cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1374cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1375cc53ce53SDavid Howells * other than its daemon the right to mount on its 1376cc53ce53SDavid Howells * superstructure. 1377cc53ce53SDavid Howells * 1378cc53ce53SDavid Howells * The filesystem may sleep at this point. 1379cc53ce53SDavid Howells */ 1380cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1381cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1382cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1383fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1384cc53ce53SDavid Howells if (ret < 0) 1385cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1386cc53ce53SDavid Howells } 1387cc53ce53SDavid Howells 1388cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1389cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1390cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1391cc53ce53SDavid Howells if (!mounted) 1392cc53ce53SDavid Howells break; 1393cc53ce53SDavid Howells dput(path->dentry); 1394cc53ce53SDavid Howells mntput(path->mnt); 1395cc53ce53SDavid Howells path->mnt = mounted; 1396cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1397cc53ce53SDavid Howells continue; 1398cc53ce53SDavid Howells } 1399cc53ce53SDavid Howells 1400cc53ce53SDavid Howells /* Don't handle automount points here */ 1401cc53ce53SDavid Howells break; 1402cc53ce53SDavid Howells } 1403cc53ce53SDavid Howells return 0; 1404cc53ce53SDavid Howells } 14054d359507SAl Viro EXPORT_SYMBOL(follow_down); 1406cc53ce53SDavid Howells 1407cc53ce53SDavid Howells /* 14089875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14099875cf80SDavid Howells */ 14109875cf80SDavid Howells static void follow_mount(struct path *path) 14119875cf80SDavid Howells { 14129875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14139875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14149875cf80SDavid Howells if (!mounted) 14159875cf80SDavid Howells break; 14169875cf80SDavid Howells dput(path->dentry); 14179875cf80SDavid Howells mntput(path->mnt); 14189875cf80SDavid Howells path->mnt = mounted; 14199875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14209875cf80SDavid Howells } 14219875cf80SDavid Howells } 14229875cf80SDavid Howells 1423eedf265aSEric W. Biederman static int path_parent_directory(struct path *path) 1424eedf265aSEric W. Biederman { 1425eedf265aSEric W. Biederman struct dentry *old = path->dentry; 1426eedf265aSEric W. Biederman /* rare case of legitimate dget_parent()... */ 1427eedf265aSEric W. Biederman path->dentry = dget_parent(path->dentry); 1428eedf265aSEric W. Biederman dput(old); 1429eedf265aSEric W. Biederman if (unlikely(!path_connected(path))) 1430eedf265aSEric W. Biederman return -ENOENT; 1431eedf265aSEric W. Biederman return 0; 1432eedf265aSEric W. Biederman } 1433eedf265aSEric W. Biederman 1434397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14351da177e4SLinus Torvalds { 14361da177e4SLinus Torvalds while(1) { 14372a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 14382a737871SAl Viro nd->path.mnt == nd->root.mnt) { 14391da177e4SLinus Torvalds break; 14401da177e4SLinus Torvalds } 14414ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1442eedf265aSEric W. Biederman int ret = path_parent_directory(&nd->path); 1443eedf265aSEric W. Biederman if (ret) 1444eedf265aSEric W. Biederman return ret; 14451da177e4SLinus Torvalds break; 14461da177e4SLinus Torvalds } 14473088dd70SAl Viro if (!follow_up(&nd->path)) 14481da177e4SLinus Torvalds break; 14491da177e4SLinus Torvalds } 145079ed0226SAl Viro follow_mount(&nd->path); 145131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1452397d425dSEric W. Biederman return 0; 14531da177e4SLinus Torvalds } 14541da177e4SLinus Torvalds 14551da177e4SLinus Torvalds /* 1456f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1457f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1458baa03890SNick Piggin */ 1459e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1460e3c13928SAl Viro struct dentry *dir, 14616c51e513SAl Viro unsigned int flags) 1462baa03890SNick Piggin { 1463a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1464bad61189SMiklos Szeredi if (dentry) { 1465a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1466bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 146774ff0ffcSAl Viro if (!error) 14685542aa2fSEric W. Biederman d_invalidate(dentry); 1469bad61189SMiklos Szeredi dput(dentry); 147074ff0ffcSAl Viro return ERR_PTR(error); 1471bad61189SMiklos Szeredi } 1472bad61189SMiklos Szeredi } 1473baa03890SNick Piggin return dentry; 1474baa03890SNick Piggin } 1475baa03890SNick Piggin 1476baa03890SNick Piggin /* 1477a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1478a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1479a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1480a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1481a03ece5fSAl Viro * at all. 148244396f4bSJosef Bacik */ 1483a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1484a03ece5fSAl Viro struct dentry *base, unsigned int flags) 148544396f4bSJosef Bacik { 1486a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 148744396f4bSJosef Bacik struct dentry *old; 1488a03ece5fSAl Viro struct inode *dir = base->d_inode; 1489a03ece5fSAl Viro 1490a03ece5fSAl Viro if (dentry) 1491a03ece5fSAl Viro return dentry; 149244396f4bSJosef Bacik 149344396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1494a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 149544396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1496a03ece5fSAl Viro 1497a03ece5fSAl Viro dentry = d_alloc(base, name); 1498a03ece5fSAl Viro if (unlikely(!dentry)) 1499a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 150044396f4bSJosef Bacik 150172bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 150244396f4bSJosef Bacik if (unlikely(old)) { 150344396f4bSJosef Bacik dput(dentry); 150444396f4bSJosef Bacik dentry = old; 150544396f4bSJosef Bacik } 150644396f4bSJosef Bacik return dentry; 150744396f4bSJosef Bacik } 150844396f4bSJosef Bacik 1509e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 1510254cf582SAl Viro struct path *path, struct inode **inode, 1511254cf582SAl Viro unsigned *seqp) 15121da177e4SLinus Torvalds { 15134ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 151431e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15155a18fff2SAl Viro int status = 1; 15169875cf80SDavid Howells int err; 15179875cf80SDavid Howells 15183cac260aSAl Viro /* 1519b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15205d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15215d0f49c1SAl Viro * going to fall back to non-racy lookup. 1522b04f784eSNick Piggin */ 152331e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 152431e6b01fSNick Piggin unsigned seq; 1525766c4cbfSAl Viro bool negative; 1526da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15275d0f49c1SAl Viro if (unlikely(!dentry)) { 15284675ac39SAl Viro if (unlazy_walk(nd)) 15295d0f49c1SAl Viro return -ECHILD; 1530e9742b53SAl Viro return 0; 15315d0f49c1SAl Viro } 15325a18fff2SAl Viro 153312f8ad4bSLinus Torvalds /* 153412f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 153512f8ad4bSLinus Torvalds * the dentry name information from lookup. 153612f8ad4bSLinus Torvalds */ 153763afdfc7SDavid Howells *inode = d_backing_inode(dentry); 1538766c4cbfSAl Viro negative = d_is_negative(dentry); 15395d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 154012f8ad4bSLinus Torvalds return -ECHILD; 154112f8ad4bSLinus Torvalds 154212f8ad4bSLinus Torvalds /* 154312f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 154412f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 154512f8ad4bSLinus Torvalds * 154612f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 154712f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 154812f8ad4bSLinus Torvalds */ 15495d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 155031e6b01fSNick Piggin return -ECHILD; 15515a18fff2SAl Viro 1552254cf582SAl Viro *seqp = seq; 15534ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1554209a7fb2SAl Viro if (likely(status > 0)) { 1555daf3761cSTrond Myklebust /* 1556daf3761cSTrond Myklebust * Note: do negative dentry check after revalidation in 1557daf3761cSTrond Myklebust * case that drops it. 1558daf3761cSTrond Myklebust */ 15595d0f49c1SAl Viro if (unlikely(negative)) 1560daf3761cSTrond Myklebust return -ENOENT; 156131e6b01fSNick Piggin path->mnt = mnt; 156231e6b01fSNick Piggin path->dentry = dentry; 1563254cf582SAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 1564e9742b53SAl Viro return 1; 15655d0f49c1SAl Viro } 15664675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 1567254cf582SAl Viro return -ECHILD; 1568209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1569209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1570209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15715a18fff2SAl Viro } else { 1572e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157381e6f520SAl Viro if (unlikely(!dentry)) 1574e9742b53SAl Viro return 0; 15754ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15765d0f49c1SAl Viro } 15775a18fff2SAl Viro if (unlikely(status <= 0)) { 1578e9742b53SAl Viro if (!status) 15795d0f49c1SAl Viro d_invalidate(dentry); 15805a18fff2SAl Viro dput(dentry); 15815a18fff2SAl Viro return status; 15825a18fff2SAl Viro } 1583766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1584766c4cbfSAl Viro dput(dentry); 1585766c4cbfSAl Viro return -ENOENT; 1586766c4cbfSAl Viro } 15875d0f49c1SAl Viro 15881da177e4SLinus Torvalds path->mnt = mnt; 15891da177e4SLinus Torvalds path->dentry = dentry; 1590756daf26SNeilBrown err = follow_managed(path, nd); 1591e9742b53SAl Viro if (likely(err > 0)) 159263afdfc7SDavid Howells *inode = d_backing_inode(path->dentry); 15938402752eSAl Viro return err; 1594697f514dSMiklos Szeredi } 1595697f514dSMiklos Szeredi 1596697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 159788d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1598e3c13928SAl Viro struct dentry *dir, 1599e3c13928SAl Viro unsigned int flags) 1600697f514dSMiklos Szeredi { 160188d8331aSAl Viro struct dentry *dentry, *old; 16021936386eSAl Viro struct inode *inode = dir->d_inode; 1603d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 16041936386eSAl Viro 16051936386eSAl Viro /* Don't go there if it's already dead */ 160694bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 160788d8331aSAl Viro return ERR_PTR(-ENOENT); 160894bdd655SAl Viro again: 1609d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 161094bdd655SAl Viro if (IS_ERR(dentry)) 161188d8331aSAl Viro return dentry; 161294bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1613a89f8337SAl Viro if (!(flags & LOOKUP_NO_REVAL)) { 1614949a852eSAl Viro int error = d_revalidate(dentry, flags); 1615949a852eSAl Viro if (unlikely(error <= 0)) { 161694bdd655SAl Viro if (!error) { 1617949a852eSAl Viro d_invalidate(dentry); 1618949a852eSAl Viro dput(dentry); 161994bdd655SAl Viro goto again; 162094bdd655SAl Viro } 162194bdd655SAl Viro dput(dentry); 1622949a852eSAl Viro dentry = ERR_PTR(error); 1623949a852eSAl Viro } 1624949a852eSAl Viro } 162594bdd655SAl Viro } else { 16261936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 162785c7f810SAl Viro d_lookup_done(dentry); 16281936386eSAl Viro if (unlikely(old)) { 16291936386eSAl Viro dput(dentry); 16301936386eSAl Viro dentry = old; 1631949a852eSAl Viro } 1632949a852eSAl Viro } 1633e3c13928SAl Viro return dentry; 16341da177e4SLinus Torvalds } 16351da177e4SLinus Torvalds 163688d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 163788d8331aSAl Viro struct dentry *dir, 163888d8331aSAl Viro unsigned int flags) 163988d8331aSAl Viro { 164088d8331aSAl Viro struct inode *inode = dir->d_inode; 164188d8331aSAl Viro struct dentry *res; 164288d8331aSAl Viro inode_lock_shared(inode); 164388d8331aSAl Viro res = __lookup_slow(name, dir, flags); 164488d8331aSAl Viro inode_unlock_shared(inode); 164588d8331aSAl Viro return res; 164688d8331aSAl Viro } 164788d8331aSAl Viro 164852094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164952094c8aSAl Viro { 165052094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16514ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 165252094c8aSAl Viro if (err != -ECHILD) 165352094c8aSAl Viro return err; 16544675ac39SAl Viro if (unlazy_walk(nd)) 165552094c8aSAl Viro return -ECHILD; 165652094c8aSAl Viro } 16574ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165852094c8aSAl Viro } 165952094c8aSAl Viro 16609856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16619856fa1bSAl Viro { 16629856fa1bSAl Viro if (type == LAST_DOTDOT) { 16639e6697e2SAl Viro if (!nd->root.mnt) 16649e6697e2SAl Viro set_root(nd); 16659856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 166670291aecSAl Viro return follow_dotdot_rcu(nd); 16679856fa1bSAl Viro } else 1668397d425dSEric W. Biederman return follow_dotdot(nd); 16699856fa1bSAl Viro } 16709856fa1bSAl Viro return 0; 16719856fa1bSAl Viro } 16729856fa1bSAl Viro 1673181548c0SAl Viro static int pick_link(struct nameidata *nd, struct path *link, 1674181548c0SAl Viro struct inode *inode, unsigned seq) 1675d63ff28fSAl Viro { 1676626de996SAl Viro int error; 16771cf2665bSAl Viro struct saved *last; 1678756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1679626de996SAl Viro path_to_nameidata(link, nd); 1680626de996SAl Viro return -ELOOP; 1681626de996SAl Viro } 1682bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1683cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1684cd179f44SAl Viro mntget(link->mnt); 16857973387aSAl Viro } 1686626de996SAl Viro error = nd_alloc_stack(nd); 1687626de996SAl Viro if (unlikely(error)) { 1688bc40aee0SAl Viro if (error == -ECHILD) { 1689ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1690ad1633a1SAl Viro drop_links(nd); 1691ad1633a1SAl Viro nd->depth = 0; 1692ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1693ad1633a1SAl Viro nd->path.mnt = NULL; 1694ad1633a1SAl Viro nd->path.dentry = NULL; 1695ad1633a1SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1696ad1633a1SAl Viro nd->root.mnt = NULL; 1697ad1633a1SAl Viro rcu_read_unlock(); 16984675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1699bc40aee0SAl Viro error = nd_alloc_stack(nd); 1700bc40aee0SAl Viro } 1701bc40aee0SAl Viro if (error) { 1702cd179f44SAl Viro path_put(link); 1703626de996SAl Viro return error; 1704626de996SAl Viro } 1705bc40aee0SAl Viro } 1706626de996SAl Viro 1707ab104923SAl Viro last = nd->stack + nd->depth++; 17081cf2665bSAl Viro last->link = *link; 1709fceef393SAl Viro clear_delayed_call(&last->done); 1710fceef393SAl Viro nd->link_inode = inode; 17110450b2d1SAl Viro last->seq = seq; 1712d63ff28fSAl Viro return 1; 1713d63ff28fSAl Viro } 1714d63ff28fSAl Viro 17158f64fb1cSAl Viro enum {WALK_FOLLOW = 1, WALK_MORE = 2}; 171631d66bcdSAl Viro 17173ddcd056SLinus Torvalds /* 17183ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17193ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17203ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17213ddcd056SLinus Torvalds * for the common case. 17223ddcd056SLinus Torvalds */ 17238f64fb1cSAl Viro static inline int step_into(struct nameidata *nd, struct path *path, 17248f64fb1cSAl Viro int flags, struct inode *inode, unsigned seq) 17253ddcd056SLinus Torvalds { 172631d66bcdSAl Viro if (!(flags & WALK_MORE) && nd->depth) 172731d66bcdSAl Viro put_link(nd); 17288f64fb1cSAl Viro if (likely(!d_is_symlink(path->dentry)) || 17298f64fb1cSAl Viro !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { 17308f64fb1cSAl Viro /* not a symlink or should not follow */ 17318f64fb1cSAl Viro path_to_nameidata(path, nd); 17328f64fb1cSAl Viro nd->inode = inode; 17338f64fb1cSAl Viro nd->seq = seq; 1734d63ff28fSAl Viro return 0; 17358f64fb1cSAl Viro } 1736a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1737a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 17388f64fb1cSAl Viro if (read_seqcount_retry(&path->dentry->d_seq, seq)) 1739a7f77542SAl Viro return -ECHILD; 1740a7f77542SAl Viro } 17418f64fb1cSAl Viro return pick_link(nd, path, inode, seq); 17423ddcd056SLinus Torvalds } 17433ddcd056SLinus Torvalds 17444693a547SAl Viro static int walk_component(struct nameidata *nd, int flags) 1745ce57dfc1SAl Viro { 1746caa85634SAl Viro struct path path; 1747ce57dfc1SAl Viro struct inode *inode; 1748254cf582SAl Viro unsigned seq; 1749ce57dfc1SAl Viro int err; 1750ce57dfc1SAl Viro /* 1751ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1752ce57dfc1SAl Viro * to be able to know about the current root directory and 1753ce57dfc1SAl Viro * parent relationships. 1754ce57dfc1SAl Viro */ 17554693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 17564693a547SAl Viro err = handle_dots(nd, nd->last_type); 17571c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 17584693a547SAl Viro put_link(nd); 17594693a547SAl Viro return err; 17604693a547SAl Viro } 1761254cf582SAl Viro err = lookup_fast(nd, &path, &inode, &seq); 1762e9742b53SAl Viro if (unlikely(err <= 0)) { 1763697f514dSMiklos Szeredi if (err < 0) 1764f0a9ba70SAl Viro return err; 1765e3c13928SAl Viro path.dentry = lookup_slow(&nd->last, nd->path.dentry, 1766e3c13928SAl Viro nd->flags); 1767e3c13928SAl Viro if (IS_ERR(path.dentry)) 1768e3c13928SAl Viro return PTR_ERR(path.dentry); 17697500c38aSAl Viro 1770e3c13928SAl Viro path.mnt = nd->path.mnt; 1771e3c13928SAl Viro err = follow_managed(&path, nd); 1772e3c13928SAl Viro if (unlikely(err < 0)) 1773f0a9ba70SAl Viro return err; 1774697f514dSMiklos Szeredi 17757500c38aSAl Viro if (unlikely(d_is_negative(path.dentry))) { 17767500c38aSAl Viro path_to_nameidata(&path, nd); 17777500c38aSAl Viro return -ENOENT; 17787500c38aSAl Viro } 17797500c38aSAl Viro 1780254cf582SAl Viro seq = 0; /* we are already out of RCU mode */ 1781d4565649SAl Viro inode = d_backing_inode(path.dentry); 1782766c4cbfSAl Viro } 1783697f514dSMiklos Szeredi 17848f64fb1cSAl Viro return step_into(nd, &path, flags, inode, seq); 1785ce57dfc1SAl Viro } 1786ce57dfc1SAl Viro 17871da177e4SLinus Torvalds /* 1788bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1789bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1790bfcfaa77SLinus Torvalds * 1791bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1792bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1793bfcfaa77SLinus Torvalds * fast. 1794bfcfaa77SLinus Torvalds * 1795bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1796bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1797bfcfaa77SLinus Torvalds * crossing operation. 1798bfcfaa77SLinus Torvalds * 1799bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1800bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1801bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1802bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1803bfcfaa77SLinus Torvalds */ 1804bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1805bfcfaa77SLinus Torvalds 1806f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1807bfcfaa77SLinus Torvalds 1808468a9428SGeorge Spelvin #ifdef HASH_MIX 1809bfcfaa77SLinus Torvalds 1810468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1811468a9428SGeorge Spelvin 1812468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18132a18da7aSGeorge Spelvin /* 18142a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18152a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18162a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18172a18da7aSGeorge Spelvin * and no temporaries. 18182a18da7aSGeorge Spelvin * 18192a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18202a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18212a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18222a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18232a18da7aSGeorge Spelvin * 18242a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18252a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18262a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18272a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18282a18da7aSGeorge Spelvin * 18292a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18302a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18312a18da7aSGeorge Spelvin * toggling any given output bit. 18322a18da7aSGeorge Spelvin * 18332a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18342a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18352a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18362a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18372a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18382a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18392a18da7aSGeorge Spelvin * Perfect: 8192 258048 18402a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 18412a18da7aSGeorge Spelvin */ 18422a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18432a18da7aSGeorge Spelvin ( x ^= (a), \ 18442a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 18452a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 18462a18da7aSGeorge Spelvin y *= 9 ) 1847bfcfaa77SLinus Torvalds 18480fed3ac8SGeorge Spelvin /* 18492a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 18502a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 18512a18da7aSGeorge Spelvin * work done before the hash value is used. 18520fed3ac8SGeorge Spelvin */ 18532a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18540fed3ac8SGeorge Spelvin { 18552a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 18562a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 18572a18da7aSGeorge Spelvin return y >> 32; 18580fed3ac8SGeorge Spelvin } 18590fed3ac8SGeorge Spelvin 1860bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1861bfcfaa77SLinus Torvalds 18622a18da7aSGeorge Spelvin /* 18632a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 18642a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18652a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 18662a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 18672a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 18682a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 18692a18da7aSGeorge Spelvin * Perfect: 2048 31744 18702a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 18712a18da7aSGeorge Spelvin */ 18722a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 18732a18da7aSGeorge Spelvin ( x ^= (a), \ 18742a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 18752a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 18762a18da7aSGeorge Spelvin y *= 9 ) 1877bfcfaa77SLinus Torvalds 18782a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 18790fed3ac8SGeorge Spelvin { 18802a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 18812a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 18820fed3ac8SGeorge Spelvin } 18830fed3ac8SGeorge Spelvin 1884bfcfaa77SLinus Torvalds #endif 1885bfcfaa77SLinus Torvalds 18862a18da7aSGeorge Spelvin /* 18872a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 18882a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 18892a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 18902a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 18912a18da7aSGeorge Spelvin * finds the delimiter after the name. 18922a18da7aSGeorge Spelvin */ 18938387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1894bfcfaa77SLinus Torvalds { 18958387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1896bfcfaa77SLinus Torvalds 1897bfcfaa77SLinus Torvalds for (;;) { 1898fcfd2fbfSGeorge Spelvin if (!len) 1899fcfd2fbfSGeorge Spelvin goto done; 1900e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1901bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1902bfcfaa77SLinus Torvalds break; 19032a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1904bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1905bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1906bfcfaa77SLinus Torvalds } 19072a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1908bfcfaa77SLinus Torvalds done: 19092a18da7aSGeorge Spelvin return fold_hash(x, y); 1910bfcfaa77SLinus Torvalds } 1911bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1912bfcfaa77SLinus Torvalds 1913fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19148387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1915fcfd2fbfSGeorge Spelvin { 19168387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19178387ff25SLinus Torvalds unsigned long adata, mask, len; 1918fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1919fcfd2fbfSGeorge Spelvin 19208387ff25SLinus Torvalds len = 0; 19218387ff25SLinus Torvalds goto inside; 19228387ff25SLinus Torvalds 1923fcfd2fbfSGeorge Spelvin do { 19242a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1925fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19268387ff25SLinus Torvalds inside: 1927fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1928fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1929fcfd2fbfSGeorge Spelvin 1930fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1931fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19322a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1933fcfd2fbfSGeorge Spelvin 19342a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1935fcfd2fbfSGeorge Spelvin } 1936fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1937fcfd2fbfSGeorge Spelvin 1938bfcfaa77SLinus Torvalds /* 1939bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1940d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1941bfcfaa77SLinus Torvalds */ 19428387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 1943bfcfaa77SLinus Torvalds { 19448387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 19458387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 194636126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1947bfcfaa77SLinus Torvalds 19488387ff25SLinus Torvalds len = 0; 19498387ff25SLinus Torvalds goto inside; 19508387ff25SLinus Torvalds 1951bfcfaa77SLinus Torvalds do { 19522a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1953bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 19548387ff25SLinus Torvalds inside: 1955e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 195636126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 195736126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1958bfcfaa77SLinus Torvalds 195936126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 196036126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 196136126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 19622a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 196336126f8fSLinus Torvalds 19642a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1965bfcfaa77SLinus Torvalds } 1966bfcfaa77SLinus Torvalds 19672a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 1968bfcfaa77SLinus Torvalds 1969fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 19708387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 19710145acc2SLinus Torvalds { 19728387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 19730145acc2SLinus Torvalds while (len--) 1974fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 19750145acc2SLinus Torvalds return end_name_hash(hash); 19760145acc2SLinus Torvalds } 1977ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 19780145acc2SLinus Torvalds 1979fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19808387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1981fcfd2fbfSGeorge Spelvin { 19828387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 1983fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 1984fcfd2fbfSGeorge Spelvin 1985fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 1986e0ab7af9SGeorge Spelvin while (c) { 1987fcfd2fbfSGeorge Spelvin len++; 1988fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 1989fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 1990e0ab7af9SGeorge Spelvin } 1991fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 1992fcfd2fbfSGeorge Spelvin } 1993f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1994fcfd2fbfSGeorge Spelvin 19953ddcd056SLinus Torvalds /* 1996200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1997200e9ef7SLinus Torvalds * one character. 1998200e9ef7SLinus Torvalds */ 19998387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2000200e9ef7SLinus Torvalds { 20018387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2002200e9ef7SLinus Torvalds unsigned long len = 0, c; 2003200e9ef7SLinus Torvalds 2004200e9ef7SLinus Torvalds c = (unsigned char)*name; 2005200e9ef7SLinus Torvalds do { 2006200e9ef7SLinus Torvalds len++; 2007200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2008200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2009200e9ef7SLinus Torvalds } while (c && c != '/'); 2010d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2011200e9ef7SLinus Torvalds } 2012200e9ef7SLinus Torvalds 2013bfcfaa77SLinus Torvalds #endif 2014bfcfaa77SLinus Torvalds 2015200e9ef7SLinus Torvalds /* 20161da177e4SLinus Torvalds * Name resolution. 2017ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2018ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20191da177e4SLinus Torvalds * 2020ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2021ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20221da177e4SLinus Torvalds */ 20236de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20241da177e4SLinus Torvalds { 20251da177e4SLinus Torvalds int err; 20261da177e4SLinus Torvalds 20271da177e4SLinus Torvalds while (*name=='/') 20281da177e4SLinus Torvalds name++; 20291da177e4SLinus Torvalds if (!*name) 20309e18f10aSAl Viro return 0; 20311da177e4SLinus Torvalds 20321da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20331da177e4SLinus Torvalds for(;;) { 2034d6bb3e90SLinus Torvalds u64 hash_len; 2035fe479a58SAl Viro int type; 20361da177e4SLinus Torvalds 203752094c8aSAl Viro err = may_lookup(nd); 20381da177e4SLinus Torvalds if (err) 20393595e234SAl Viro return err; 20401da177e4SLinus Torvalds 20418387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 20421da177e4SLinus Torvalds 2043fe479a58SAl Viro type = LAST_NORM; 2044d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2045fe479a58SAl Viro case 2: 2046200e9ef7SLinus Torvalds if (name[1] == '.') { 2047fe479a58SAl Viro type = LAST_DOTDOT; 204816c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 204916c2cd71SAl Viro } 2050fe479a58SAl Viro break; 2051fe479a58SAl Viro case 1: 2052fe479a58SAl Viro type = LAST_DOT; 2053fe479a58SAl Viro } 20545a202bcdSAl Viro if (likely(type == LAST_NORM)) { 20555a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 205616c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 20575a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2058a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2059da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 20605a202bcdSAl Viro if (err < 0) 20613595e234SAl Viro return err; 2062d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2063d6bb3e90SLinus Torvalds name = this.name; 20645a202bcdSAl Viro } 20655a202bcdSAl Viro } 2066fe479a58SAl Viro 2067d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2068d6bb3e90SLinus Torvalds nd->last.name = name; 20695f4a6a69SAl Viro nd->last_type = type; 20705f4a6a69SAl Viro 2071d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2072d6bb3e90SLinus Torvalds if (!*name) 2073bdf6cbf1SAl Viro goto OK; 2074200e9ef7SLinus Torvalds /* 2075200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2076200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2077200e9ef7SLinus Torvalds */ 2078200e9ef7SLinus Torvalds do { 2079d6bb3e90SLinus Torvalds name++; 2080d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 20818620c238SAl Viro if (unlikely(!*name)) { 20828620c238SAl Viro OK: 2083368ee9baSAl Viro /* pathname body, done */ 20848620c238SAl Viro if (!nd->depth) 20858620c238SAl Viro return 0; 20868620c238SAl Viro name = nd->stack[nd->depth - 1].name; 2087368ee9baSAl Viro /* trailing symlink, done */ 20888620c238SAl Viro if (!name) 20898620c238SAl Viro return 0; 20908620c238SAl Viro /* last component of nested symlink */ 20918f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW); 20921c4ff1a8SAl Viro } else { 20931c4ff1a8SAl Viro /* not the last component */ 20948f64fb1cSAl Viro err = walk_component(nd, WALK_FOLLOW | WALK_MORE); 20958620c238SAl Viro } 2096ce57dfc1SAl Viro if (err < 0) 20973595e234SAl Viro return err; 2098fe479a58SAl Viro 2099ce57dfc1SAl Viro if (err) { 2100626de996SAl Viro const char *s = get_link(nd); 21015a460275SAl Viro 2102a1c83681SViresh Kumar if (IS_ERR(s)) 21033595e234SAl Viro return PTR_ERR(s); 2104172a39a0SAl Viro err = 0; 210512b09578SAl Viro if (unlikely(!s)) { 210612b09578SAl Viro /* jumped */ 2107b9ff4429SAl Viro put_link(nd); 210812b09578SAl Viro } else { 2109071bf501SAl Viro nd->stack[nd->depth - 1].name = name; 211032cd7468SAl Viro name = s; 21119e18f10aSAl Viro continue; 211248c8b0c5SAl Viro } 211331e6b01fSNick Piggin } 211497242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 211597242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21164675ac39SAl Viro if (unlazy_walk(nd)) 211797242f99SAl Viro return -ECHILD; 211897242f99SAl Viro } 21193595e234SAl Viro return -ENOTDIR; 21205f4a6a69SAl Viro } 2121ce57dfc1SAl Viro } 212297242f99SAl Viro } 21231da177e4SLinus Torvalds 2124c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 212531e6b01fSNick Piggin { 2126c8a53ee5SAl Viro const char *s = nd->name->name; 212731e6b01fSNick Piggin 2128c0eb027eSLinus Torvalds if (!*s) 2129c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2130c0eb027eSLinus Torvalds 213131e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 2132980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 213331e6b01fSNick Piggin nd->depth = 0; 21345b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2135b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2136b18825a7SDavid Howells struct inode *inode = root->d_inode; 213793893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2138368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 21395b6ca027SAl Viro nd->path = nd->root; 21405b6ca027SAl Viro nd->inode = inode; 21415b6ca027SAl Viro if (flags & LOOKUP_RCU) { 21428b61e74fSAl Viro rcu_read_lock(); 21435b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 21448f47a016SAl Viro nd->root_seq = nd->seq; 214548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 21465b6ca027SAl Viro } else { 21475b6ca027SAl Viro path_get(&nd->path); 21485b6ca027SAl Viro } 2149368ee9baSAl Viro return s; 21505b6ca027SAl Viro } 21515b6ca027SAl Viro 215231e6b01fSNick Piggin nd->root.mnt = NULL; 2153248fb5b9SAl Viro nd->path.mnt = NULL; 2154248fb5b9SAl Viro nd->path.dentry = NULL; 215531e6b01fSNick Piggin 215648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 2157fd2f7cb5SAl Viro if (*s == '/') { 21589e6697e2SAl Viro if (flags & LOOKUP_RCU) 21598b61e74fSAl Viro rcu_read_lock(); 2160e41f7d4eSAl Viro set_root(nd); 2161248fb5b9SAl Viro if (likely(!nd_jump_root(nd))) 2162ef55d917SAl Viro return s; 2163ef55d917SAl Viro nd->root.mnt = NULL; 2164ef55d917SAl Viro rcu_read_unlock(); 2165ef55d917SAl Viro return ERR_PTR(-ECHILD); 2166c8a53ee5SAl Viro } else if (nd->dfd == AT_FDCWD) { 2167e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 216831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2169c28cc364SNick Piggin unsigned seq; 217031e6b01fSNick Piggin 21718b61e74fSAl Viro rcu_read_lock(); 217231e6b01fSNick Piggin 2173c28cc364SNick Piggin do { 2174c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 217531e6b01fSNick Piggin nd->path = fs->pwd; 2176ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2177c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2178c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2179e41f7d4eSAl Viro } else { 2180e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2181ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2182e41f7d4eSAl Viro } 2183ef55d917SAl Viro return s; 218431e6b01fSNick Piggin } else { 2185582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2186c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 218731e6b01fSNick Piggin struct dentry *dentry; 218831e6b01fSNick Piggin 21892903ff01SAl Viro if (!f.file) 2190368ee9baSAl Viro return ERR_PTR(-EBADF); 219131e6b01fSNick Piggin 21922903ff01SAl Viro dentry = f.file->f_path.dentry; 219331e6b01fSNick Piggin 2194fd2f7cb5SAl Viro if (*s) { 219544b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 21962903ff01SAl Viro fdput(f); 2197368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2198f52e0c11SAl Viro } 21992903ff01SAl Viro } 22002903ff01SAl Viro 22012903ff01SAl Viro nd->path = f.file->f_path; 2202e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 22038b61e74fSAl Viro rcu_read_lock(); 220434a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 220534a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22065590ff0dSUlrich Drepper } else { 22072903ff01SAl Viro path_get(&nd->path); 220834a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22091da177e4SLinus Torvalds } 221034a26b99SAl Viro fdput(f); 2211368ee9baSAl Viro return s; 2212e41f7d4eSAl Viro } 22139b4a9b14SAl Viro } 22149b4a9b14SAl Viro 22153bdba28bSAl Viro static const char *trailing_symlink(struct nameidata *nd) 221695fa25d9SAl Viro { 221795fa25d9SAl Viro const char *s; 2218fec2fa24SAl Viro int error = may_follow_link(nd); 2219deb106c6SAl Viro if (unlikely(error)) 22203bdba28bSAl Viro return ERR_PTR(error); 222195fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 2222fab51e8aSAl Viro nd->stack[0].name = NULL; 22233b2e7f75SAl Viro s = get_link(nd); 2224deb106c6SAl Viro return s ? s : ""; 222595fa25d9SAl Viro } 222695fa25d9SAl Viro 2227caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2228bd92d7feSAl Viro { 2229bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2230bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2231bd92d7feSAl Viro 2232bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 22331c4ff1a8SAl Viro return walk_component(nd, 0); 2234bd92d7feSAl Viro } 2235bd92d7feSAl Viro 22364f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22374f757f3cSAl Viro { 22384f757f3cSAl Viro struct path path = nd->path; 22394f757f3cSAl Viro struct inode *inode = nd->inode; 22404f757f3cSAl Viro unsigned seq = nd->seq; 22414f757f3cSAl Viro int err; 22424f757f3cSAl Viro 22434f757f3cSAl Viro if (nd->flags & LOOKUP_RCU) { 22444f757f3cSAl Viro /* 22454f757f3cSAl Viro * don't bother with unlazy_walk on failure - we are 22464f757f3cSAl Viro * at the very beginning of walk, so we lose nothing 22474f757f3cSAl Viro * if we simply redo everything in non-RCU mode 22484f757f3cSAl Viro */ 22494f757f3cSAl Viro if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) 22504f757f3cSAl Viro return -ECHILD; 22514f757f3cSAl Viro } else { 22524f757f3cSAl Viro dget(path.dentry); 22534f757f3cSAl Viro err = follow_managed(&path, nd); 22544f757f3cSAl Viro if (unlikely(err < 0)) 22554f757f3cSAl Viro return err; 22564f757f3cSAl Viro inode = d_backing_inode(path.dentry); 22574f757f3cSAl Viro seq = 0; 22584f757f3cSAl Viro } 22594f757f3cSAl Viro path_to_nameidata(&path, nd); 22604f757f3cSAl Viro nd->inode = inode; 22614f757f3cSAl Viro nd->seq = seq; 22624f757f3cSAl Viro return 0; 22634f757f3cSAl Viro } 22644f757f3cSAl Viro 22659b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2266c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22679b4a9b14SAl Viro { 2268c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2269bd92d7feSAl Viro int err; 227031e6b01fSNick Piggin 2271368ee9baSAl Viro if (IS_ERR(s)) 2272368ee9baSAl Viro return PTR_ERR(s); 22734f757f3cSAl Viro 22744f757f3cSAl Viro if (unlikely(flags & LOOKUP_DOWN)) { 22754f757f3cSAl Viro err = handle_lookup_down(nd); 22764f757f3cSAl Viro if (unlikely(err < 0)) { 22774f757f3cSAl Viro terminate_walk(nd); 22784f757f3cSAl Viro return err; 22794f757f3cSAl Viro } 22804f757f3cSAl Viro } 22814f757f3cSAl Viro 22823bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) 22833bdba28bSAl Viro && ((err = lookup_last(nd)) > 0)) { 22843bdba28bSAl Viro s = trailing_symlink(nd); 22853bdba28bSAl Viro if (IS_ERR(s)) { 22863bdba28bSAl Viro err = PTR_ERR(s); 22876d7b5aaeSAl Viro break; 2288bd92d7feSAl Viro } 2289bd92d7feSAl Viro } 22909f1fafeeSAl Viro if (!err) 22919f1fafeeSAl Viro err = complete_walk(nd); 2292bd92d7feSAl Viro 2293deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2294deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2295bd23a539SAl Viro err = -ENOTDIR; 2296625b6d10SAl Viro if (!err) { 2297625b6d10SAl Viro *path = nd->path; 2298625b6d10SAl Viro nd->path.mnt = NULL; 2299625b6d10SAl Viro nd->path.dentry = NULL; 2300625b6d10SAl Viro } 2301deb106c6SAl Viro terminate_walk(nd); 2302bd92d7feSAl Viro return err; 230331e6b01fSNick Piggin } 230431e6b01fSNick Piggin 2305625b6d10SAl Viro static int filename_lookup(int dfd, struct filename *name, unsigned flags, 23069ad1aaa6SAl Viro struct path *path, struct path *root) 2307873f1eedSJeff Layton { 2308894bc8c4SAl Viro int retval; 23099883d185SAl Viro struct nameidata nd; 2310abc9f5beSAl Viro if (IS_ERR(name)) 2311abc9f5beSAl Viro return PTR_ERR(name); 23129ad1aaa6SAl Viro if (unlikely(root)) { 23139ad1aaa6SAl Viro nd.root = *root; 23149ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23159ad1aaa6SAl Viro } 23169883d185SAl Viro set_nameidata(&nd, dfd, name); 2317c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2318873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2319c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2320873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2321c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2322873f1eedSJeff Layton 2323873f1eedSJeff Layton if (likely(!retval)) 2324625b6d10SAl Viro audit_inode(name, path->dentry, flags & LOOKUP_PARENT); 23259883d185SAl Viro restore_nameidata(); 2326e4bd1c1aSAl Viro putname(name); 2327873f1eedSJeff Layton return retval; 2328873f1eedSJeff Layton } 2329873f1eedSJeff Layton 23308bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2331c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2332391172c4SAl Viro struct path *parent) 23338bcb77faSAl Viro { 2334c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2335368ee9baSAl Viro int err; 2336368ee9baSAl Viro if (IS_ERR(s)) 2337368ee9baSAl Viro return PTR_ERR(s); 2338368ee9baSAl Viro err = link_path_walk(s, nd); 23398bcb77faSAl Viro if (!err) 23408bcb77faSAl Viro err = complete_walk(nd); 2341391172c4SAl Viro if (!err) { 2342391172c4SAl Viro *parent = nd->path; 2343391172c4SAl Viro nd->path.mnt = NULL; 2344391172c4SAl Viro nd->path.dentry = NULL; 2345391172c4SAl Viro } 2346deb106c6SAl Viro terminate_walk(nd); 23478bcb77faSAl Viro return err; 23488bcb77faSAl Viro } 23498bcb77faSAl Viro 23505c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2351391172c4SAl Viro unsigned int flags, struct path *parent, 2352391172c4SAl Viro struct qstr *last, int *type) 23538bcb77faSAl Viro { 23548bcb77faSAl Viro int retval; 23559883d185SAl Viro struct nameidata nd; 23568bcb77faSAl Viro 23575c31b6ceSAl Viro if (IS_ERR(name)) 23585c31b6ceSAl Viro return name; 23599883d185SAl Viro set_nameidata(&nd, dfd, name); 2360c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23618bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2362c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23638bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2364c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2365391172c4SAl Viro if (likely(!retval)) { 2366391172c4SAl Viro *last = nd.last; 2367391172c4SAl Viro *type = nd.last_type; 2368391172c4SAl Viro audit_inode(name, parent->dentry, LOOKUP_PARENT); 23695c31b6ceSAl Viro } else { 23705c31b6ceSAl Viro putname(name); 23715c31b6ceSAl Viro name = ERR_PTR(retval); 2372391172c4SAl Viro } 23739883d185SAl Viro restore_nameidata(); 23745c31b6ceSAl Viro return name; 23758bcb77faSAl Viro } 23768bcb77faSAl Viro 237779714f72SAl Viro /* does lookup, returns the object with parent locked */ 237879714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 23795590ff0dSUlrich Drepper { 23805c31b6ceSAl Viro struct filename *filename; 23815c31b6ceSAl Viro struct dentry *d; 2382391172c4SAl Viro struct qstr last; 2383391172c4SAl Viro int type; 238451689104SPaul Moore 23855c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 23865c31b6ceSAl Viro &last, &type); 238751689104SPaul Moore if (IS_ERR(filename)) 238851689104SPaul Moore return ERR_CAST(filename); 23895c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2390391172c4SAl Viro path_put(path); 23915c31b6ceSAl Viro putname(filename); 23925c31b6ceSAl Viro return ERR_PTR(-EINVAL); 239379714f72SAl Viro } 23945955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2395391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 239679714f72SAl Viro if (IS_ERR(d)) { 23975955102cSAl Viro inode_unlock(path->dentry->d_inode); 2398391172c4SAl Viro path_put(path); 239979714f72SAl Viro } 240051689104SPaul Moore putname(filename); 240179714f72SAl Viro return d; 24025590ff0dSUlrich Drepper } 24035590ff0dSUlrich Drepper 2404d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2405d1811465SAl Viro { 2406abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2407abc9f5beSAl Viro flags, path, NULL); 2408d1811465SAl Viro } 24094d359507SAl Viro EXPORT_SYMBOL(kern_path); 2410d1811465SAl Viro 241116f18200SJosef 'Jeff' Sipek /** 241216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 241316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 241416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 241516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 241616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2417e0a01249SAl Viro * @path: pointer to struct path to fill 241816f18200SJosef 'Jeff' Sipek */ 241916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 242016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2421e0a01249SAl Viro struct path *path) 242216f18200SJosef 'Jeff' Sipek { 24239ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24249ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2425abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2426abc9f5beSAl Viro flags , path, &root); 242716f18200SJosef 'Jeff' Sipek } 24284d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 242916f18200SJosef 'Jeff' Sipek 24303c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24313c95f0dcSAl Viro int len, struct qstr *this) 24323c95f0dcSAl Viro { 24333c95f0dcSAl Viro this->name = name; 24343c95f0dcSAl Viro this->len = len; 24353c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24363c95f0dcSAl Viro if (!len) 24373c95f0dcSAl Viro return -EACCES; 24383c95f0dcSAl Viro 24393c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24403c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24413c95f0dcSAl Viro return -EACCES; 24423c95f0dcSAl Viro } 24433c95f0dcSAl Viro 24443c95f0dcSAl Viro while (len--) { 24453c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24463c95f0dcSAl Viro if (c == '/' || c == '\0') 24473c95f0dcSAl Viro return -EACCES; 24483c95f0dcSAl Viro } 24493c95f0dcSAl Viro /* 24503c95f0dcSAl Viro * See if the low-level filesystem might want 24513c95f0dcSAl Viro * to use its own hash.. 24523c95f0dcSAl Viro */ 24533c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24543c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24553c95f0dcSAl Viro if (err < 0) 24563c95f0dcSAl Viro return err; 24573c95f0dcSAl Viro } 24583c95f0dcSAl Viro 24593c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24603c95f0dcSAl Viro } 24613c95f0dcSAl Viro 2462eead1911SChristoph Hellwig /** 2463a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2464eead1911SChristoph Hellwig * @name: pathname component to lookup 2465eead1911SChristoph Hellwig * @base: base directory to lookup from 2466eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2467eead1911SChristoph Hellwig * 2468a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 24699e7543e9SAl Viro * not be called by generic code. 2470bbddca8eSNeilBrown * 2471bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2472eead1911SChristoph Hellwig */ 2473057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2474057f6c01SJames Morris { 24758613a209SAl Viro struct dentry *dentry; 2476057f6c01SJames Morris struct qstr this; 2477cda309deSMiklos Szeredi int err; 2478057f6c01SJames Morris 24795955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 24802f9092e1SDavid Woodhouse 24813c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2482cda309deSMiklos Szeredi if (err) 2483cda309deSMiklos Szeredi return ERR_PTR(err); 2484cda309deSMiklos Szeredi 24858613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 24868613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2487057f6c01SJames Morris } 24884d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2489057f6c01SJames Morris 2490bbddca8eSNeilBrown /** 2491bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2492bbddca8eSNeilBrown * @name: pathname component to lookup 2493bbddca8eSNeilBrown * @base: base directory to lookup from 2494bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2495bbddca8eSNeilBrown * 2496bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2497bbddca8eSNeilBrown * not be called by generic code. 2498bbddca8eSNeilBrown * 2499bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2500bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2501bbddca8eSNeilBrown */ 2502bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2503bbddca8eSNeilBrown struct dentry *base, int len) 2504bbddca8eSNeilBrown { 2505bbddca8eSNeilBrown struct qstr this; 2506bbddca8eSNeilBrown int err; 250720d00ee8SLinus Torvalds struct dentry *ret; 2508bbddca8eSNeilBrown 25093c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2510bbddca8eSNeilBrown if (err) 2511bbddca8eSNeilBrown return ERR_PTR(err); 2512bbddca8eSNeilBrown 251320d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 251420d00ee8SLinus Torvalds if (!ret) 251520d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 251620d00ee8SLinus Torvalds return ret; 2517bbddca8eSNeilBrown } 2518bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2519bbddca8eSNeilBrown 2520eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2521eedf265aSEric W. Biederman int path_pts(struct path *path) 2522eedf265aSEric W. Biederman { 2523eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2524eedf265aSEric W. Biederman * the input path. 2525eedf265aSEric W. Biederman */ 2526eedf265aSEric W. Biederman struct dentry *child, *parent; 2527eedf265aSEric W. Biederman struct qstr this; 2528eedf265aSEric W. Biederman int ret; 2529eedf265aSEric W. Biederman 2530eedf265aSEric W. Biederman ret = path_parent_directory(path); 2531eedf265aSEric W. Biederman if (ret) 2532eedf265aSEric W. Biederman return ret; 2533eedf265aSEric W. Biederman 2534eedf265aSEric W. Biederman parent = path->dentry; 2535eedf265aSEric W. Biederman this.name = "pts"; 2536eedf265aSEric W. Biederman this.len = 3; 2537eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2538eedf265aSEric W. Biederman if (!child) 2539eedf265aSEric W. Biederman return -ENOENT; 2540eedf265aSEric W. Biederman 2541eedf265aSEric W. Biederman path->dentry = child; 2542eedf265aSEric W. Biederman dput(parent); 2543eedf265aSEric W. Biederman follow_mount(path); 2544eedf265aSEric W. Biederman return 0; 2545eedf265aSEric W. Biederman } 2546eedf265aSEric W. Biederman #endif 2547eedf265aSEric W. Biederman 25481fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 25491fa1e7f6SAndy Whitcroft struct path *path, int *empty) 25501da177e4SLinus Torvalds { 2551abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2552abc9f5beSAl Viro flags, path, NULL); 25531da177e4SLinus Torvalds } 2554b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 25551fa1e7f6SAndy Whitcroft 25568033426eSJeff Layton /** 2557197df04cSAl Viro * mountpoint_last - look up last component for umount 25588033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 25598033426eSJeff Layton * 25608033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 25618033426eSJeff Layton * need to resolve the path without doing any revalidation. 25628033426eSJeff Layton * 25638033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 25648033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 25658033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 25668033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 25678033426eSJeff Layton * bogus and it doesn't exist. 25688033426eSJeff Layton * 25698033426eSJeff Layton * Returns: 25708033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 2571ba8f4613SAl Viro * lookup found a negative dentry. 25728033426eSJeff Layton * 2573ba8f4613SAl Viro * 0: if we successfully resolved nd->last and found it to not to be a 2574ba8f4613SAl Viro * symlink that needs to be followed. 25758033426eSJeff Layton * 25768033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 2577ba8f4613SAl Viro * that needs to be followed. 25788033426eSJeff Layton */ 25798033426eSJeff Layton static int 2580ba8f4613SAl Viro mountpoint_last(struct nameidata *nd) 25818033426eSJeff Layton { 25828033426eSJeff Layton int error = 0; 25838033426eSJeff Layton struct dentry *dir = nd->path.dentry; 2584ba8f4613SAl Viro struct path path; 25858033426eSJeff Layton 258635759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 258735759521SAl Viro if (nd->flags & LOOKUP_RCU) { 25884675ac39SAl Viro if (unlazy_walk(nd)) 2589deb106c6SAl Viro return -ECHILD; 25908033426eSJeff Layton } 25918033426eSJeff Layton 25928033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 25938033426eSJeff Layton 25948033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 25958033426eSJeff Layton error = handle_dots(nd, nd->last_type); 259635759521SAl Viro if (error) 2597deb106c6SAl Viro return error; 2598ba8f4613SAl Viro path.dentry = dget(nd->path.dentry); 2599949a852eSAl Viro } else { 2600ba8f4613SAl Viro path.dentry = d_lookup(dir, &nd->last); 2601ba8f4613SAl Viro if (!path.dentry) { 26028033426eSJeff Layton /* 2603949a852eSAl Viro * No cached dentry. Mounted dentries are pinned in the 2604949a852eSAl Viro * cache, so that means that this dentry is probably 2605949a852eSAl Viro * a symlink or the path doesn't actually point 2606949a852eSAl Viro * to a mounted dentry. 26078033426eSJeff Layton */ 2608ba8f4613SAl Viro path.dentry = lookup_slow(&nd->last, dir, 2609949a852eSAl Viro nd->flags | LOOKUP_NO_REVAL); 2610ba8f4613SAl Viro if (IS_ERR(path.dentry)) 2611ba8f4613SAl Viro return PTR_ERR(path.dentry); 26128033426eSJeff Layton } 2613bcceeebaSDave Jones } 2614ba8f4613SAl Viro if (d_is_negative(path.dentry)) { 2615ba8f4613SAl Viro dput(path.dentry); 2616deb106c6SAl Viro return -ENOENT; 261735759521SAl Viro } 2618ba8f4613SAl Viro path.mnt = nd->path.mnt; 26198f64fb1cSAl Viro return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); 26208033426eSJeff Layton } 26218033426eSJeff Layton 26228033426eSJeff Layton /** 2623197df04cSAl Viro * path_mountpoint - look up a path to be umounted 26242a78b857SMasanari Iida * @nd: lookup context 26258033426eSJeff Layton * @flags: lookup flags 2626c8a53ee5SAl Viro * @path: pointer to container for result 26278033426eSJeff Layton * 26288033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2629606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 26308033426eSJeff Layton */ 26318033426eSJeff Layton static int 2632c8a53ee5SAl Viro path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) 26338033426eSJeff Layton { 2634c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2635368ee9baSAl Viro int err; 2636368ee9baSAl Viro if (IS_ERR(s)) 2637368ee9baSAl Viro return PTR_ERR(s); 26383bdba28bSAl Viro while (!(err = link_path_walk(s, nd)) && 2639ba8f4613SAl Viro (err = mountpoint_last(nd)) > 0) { 26403bdba28bSAl Viro s = trailing_symlink(nd); 26413bdba28bSAl Viro if (IS_ERR(s)) { 26423bdba28bSAl Viro err = PTR_ERR(s); 26438033426eSJeff Layton break; 26448033426eSJeff Layton } 26453bdba28bSAl Viro } 2646ba8f4613SAl Viro if (!err) { 2647ba8f4613SAl Viro *path = nd->path; 2648ba8f4613SAl Viro nd->path.mnt = NULL; 2649ba8f4613SAl Viro nd->path.dentry = NULL; 2650ba8f4613SAl Viro follow_mount(path); 2651ba8f4613SAl Viro } 2652deb106c6SAl Viro terminate_walk(nd); 26538033426eSJeff Layton return err; 26548033426eSJeff Layton } 26558033426eSJeff Layton 26562d864651SAl Viro static int 2657668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 26582d864651SAl Viro unsigned int flags) 26592d864651SAl Viro { 26609883d185SAl Viro struct nameidata nd; 2661cbaab2dbSAl Viro int error; 2662668696dcSAl Viro if (IS_ERR(name)) 2663668696dcSAl Viro return PTR_ERR(name); 26649883d185SAl Viro set_nameidata(&nd, dfd, name); 2665c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); 26662d864651SAl Viro if (unlikely(error == -ECHILD)) 2667c8a53ee5SAl Viro error = path_mountpoint(&nd, flags, path); 26682d864651SAl Viro if (unlikely(error == -ESTALE)) 2669c8a53ee5SAl Viro error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); 26702d864651SAl Viro if (likely(!error)) 2671668696dcSAl Viro audit_inode(name, path->dentry, 0); 26729883d185SAl Viro restore_nameidata(); 2673668696dcSAl Viro putname(name); 26742d864651SAl Viro return error; 26752d864651SAl Viro } 26762d864651SAl Viro 26778033426eSJeff Layton /** 2678197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 26798033426eSJeff Layton * @dfd: directory file descriptor 26808033426eSJeff Layton * @name: pathname from userland 26818033426eSJeff Layton * @flags: lookup flags 26828033426eSJeff Layton * @path: pointer to container to hold result 26838033426eSJeff Layton * 26848033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 26858033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 26868033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 26878033426eSJeff Layton * and avoid revalidating the last component. 26888033426eSJeff Layton * 26898033426eSJeff Layton * Returns 0 and populates "path" on success. 26908033426eSJeff Layton */ 26918033426eSJeff Layton int 2692197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 26938033426eSJeff Layton struct path *path) 26948033426eSJeff Layton { 2695cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 26968033426eSJeff Layton } 26978033426eSJeff Layton 26982d864651SAl Viro int 26992d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 27002d864651SAl Viro unsigned int flags) 27012d864651SAl Viro { 2702cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 27032d864651SAl Viro } 27042d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 27052d864651SAl Viro 2706cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 27071da177e4SLinus Torvalds { 27088e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2709da9592edSDavid Howells 27108e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 27111da177e4SLinus Torvalds return 0; 27128e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 27131da177e4SLinus Torvalds return 0; 271423adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 27151da177e4SLinus Torvalds } 2716cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 27171da177e4SLinus Torvalds 27181da177e4SLinus Torvalds /* 27191da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 27201da177e4SLinus Torvalds * whether the type of victim is right. 27211da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 27221da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 27231da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 27241da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 27251da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 27261da177e4SLinus Torvalds * a. be owner of dir, or 27271da177e4SLinus Torvalds * b. be owner of victim, or 27281da177e4SLinus Torvalds * c. have CAP_FOWNER capability 27291da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 27301da177e4SLinus Torvalds * links pointing to it. 27310bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 27320bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 27330bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 27340bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 27350bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 27361da177e4SLinus Torvalds * nfs_async_unlink(). 27371da177e4SLinus Torvalds */ 2738b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 27391da177e4SLinus Torvalds { 274063afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 27411da177e4SLinus Torvalds int error; 27421da177e4SLinus Torvalds 2743b18825a7SDavid Howells if (d_is_negative(victim)) 27441da177e4SLinus Torvalds return -ENOENT; 2745b18825a7SDavid Howells BUG_ON(!inode); 27461da177e4SLinus Torvalds 27471da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 27484fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 27491da177e4SLinus Torvalds 2750f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27511da177e4SLinus Torvalds if (error) 27521da177e4SLinus Torvalds return error; 27531da177e4SLinus Torvalds if (IS_APPEND(dir)) 27541da177e4SLinus Torvalds return -EPERM; 2755b18825a7SDavid Howells 2756b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27570bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27581da177e4SLinus Torvalds return -EPERM; 27591da177e4SLinus Torvalds if (isdir) { 276044b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27611da177e4SLinus Torvalds return -ENOTDIR; 27621da177e4SLinus Torvalds if (IS_ROOT(victim)) 27631da177e4SLinus Torvalds return -EBUSY; 276444b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27651da177e4SLinus Torvalds return -EISDIR; 27661da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27671da177e4SLinus Torvalds return -ENOENT; 27681da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27691da177e4SLinus Torvalds return -EBUSY; 27701da177e4SLinus Torvalds return 0; 27711da177e4SLinus Torvalds } 27721da177e4SLinus Torvalds 27731da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27741da177e4SLinus Torvalds * dir. 27751da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27761da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27771da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2778036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2779036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2780036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27811da177e4SLinus Torvalds */ 2782a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27831da177e4SLinus Torvalds { 2784036d5236SEric W. Biederman struct user_namespace *s_user_ns; 278514e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27861da177e4SLinus Torvalds if (child->d_inode) 27871da177e4SLinus Torvalds return -EEXIST; 27881da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27891da177e4SLinus Torvalds return -ENOENT; 2790036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2791036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2792036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2793036d5236SEric W. Biederman return -EOVERFLOW; 2794f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27951da177e4SLinus Torvalds } 27961da177e4SLinus Torvalds 27971da177e4SLinus Torvalds /* 27981da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27991da177e4SLinus Torvalds */ 28001da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 28011da177e4SLinus Torvalds { 28021da177e4SLinus Torvalds struct dentry *p; 28031da177e4SLinus Torvalds 28041da177e4SLinus Torvalds if (p1 == p2) { 28055955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28061da177e4SLinus Torvalds return NULL; 28071da177e4SLinus Torvalds } 28081da177e4SLinus Torvalds 2809fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 28101da177e4SLinus Torvalds 2811e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2812e2761a11SOGAWA Hirofumi if (p) { 28135955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 28145955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 28151da177e4SLinus Torvalds return p; 28161da177e4SLinus Torvalds } 28171da177e4SLinus Torvalds 2818e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2819e2761a11SOGAWA Hirofumi if (p) { 28205955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28215955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 28221da177e4SLinus Torvalds return p; 28231da177e4SLinus Torvalds } 28241da177e4SLinus Torvalds 28255955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 28265955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 28271da177e4SLinus Torvalds return NULL; 28281da177e4SLinus Torvalds } 28294d359507SAl Viro EXPORT_SYMBOL(lock_rename); 28301da177e4SLinus Torvalds 28311da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 28321da177e4SLinus Torvalds { 28335955102cSAl Viro inode_unlock(p1->d_inode); 28341da177e4SLinus Torvalds if (p1 != p2) { 28355955102cSAl Viro inode_unlock(p2->d_inode); 2836fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 28371da177e4SLinus Torvalds } 28381da177e4SLinus Torvalds } 28394d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 28401da177e4SLinus Torvalds 28414acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2842312b63fbSAl Viro bool want_excl) 28431da177e4SLinus Torvalds { 2844a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 28451da177e4SLinus Torvalds if (error) 28461da177e4SLinus Torvalds return error; 28471da177e4SLinus Torvalds 2848acfa4380SAl Viro if (!dir->i_op->create) 28491da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 28501da177e4SLinus Torvalds mode &= S_IALLUGO; 28511da177e4SLinus Torvalds mode |= S_IFREG; 28521da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28531da177e4SLinus Torvalds if (error) 28541da177e4SLinus Torvalds return error; 2855312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2856a74574aaSStephen Smalley if (!error) 2857f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28581da177e4SLinus Torvalds return error; 28591da177e4SLinus Torvalds } 28604d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28611da177e4SLinus Torvalds 28628e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28638e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28648e6c848eSAl Viro void *arg) 28658e6c848eSAl Viro { 28668e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28678e6c848eSAl Viro int error = may_create(dir, dentry); 28688e6c848eSAl Viro if (error) 28698e6c848eSAl Viro return error; 28708e6c848eSAl Viro 28718e6c848eSAl Viro mode &= S_IALLUGO; 28728e6c848eSAl Viro mode |= S_IFREG; 28738e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28748e6c848eSAl Viro if (error) 28758e6c848eSAl Viro return error; 28768e6c848eSAl Viro error = f(dentry, mode, arg); 28778e6c848eSAl Viro if (!error) 28788e6c848eSAl Viro fsnotify_create(dir, dentry); 28798e6c848eSAl Viro return error; 28808e6c848eSAl Viro } 28818e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28828e6c848eSAl Viro 2883a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2884a2982cc9SEric W. Biederman { 2885a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2886a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2887a2982cc9SEric W. Biederman } 2888a2982cc9SEric W. Biederman 2889f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28901da177e4SLinus Torvalds { 28913fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28921da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28931da177e4SLinus Torvalds int error; 28941da177e4SLinus Torvalds 28951da177e4SLinus Torvalds if (!inode) 28961da177e4SLinus Torvalds return -ENOENT; 28971da177e4SLinus Torvalds 2898c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2899c8fe8f30SChristoph Hellwig case S_IFLNK: 29001da177e4SLinus Torvalds return -ELOOP; 2901c8fe8f30SChristoph Hellwig case S_IFDIR: 2902c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 29031da177e4SLinus Torvalds return -EISDIR; 2904c8fe8f30SChristoph Hellwig break; 2905c8fe8f30SChristoph Hellwig case S_IFBLK: 2906c8fe8f30SChristoph Hellwig case S_IFCHR: 2907a2982cc9SEric W. Biederman if (!may_open_dev(path)) 29081da177e4SLinus Torvalds return -EACCES; 2909c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2910c8fe8f30SChristoph Hellwig case S_IFIFO: 2911c8fe8f30SChristoph Hellwig case S_IFSOCK: 29121da177e4SLinus Torvalds flag &= ~O_TRUNC; 2913c8fe8f30SChristoph Hellwig break; 29144a3fd211SDave Hansen } 2915b41572e9SDave Hansen 291662fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2917b41572e9SDave Hansen if (error) 2918b41572e9SDave Hansen return error; 29196146f0d5SMimi Zohar 29201da177e4SLinus Torvalds /* 29211da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 29221da177e4SLinus Torvalds */ 29231da177e4SLinus Torvalds if (IS_APPEND(inode)) { 29248737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 29257715b521SAl Viro return -EPERM; 29261da177e4SLinus Torvalds if (flag & O_TRUNC) 29277715b521SAl Viro return -EPERM; 29281da177e4SLinus Torvalds } 29291da177e4SLinus Torvalds 29301da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 29312e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 29327715b521SAl Viro return -EPERM; 29331da177e4SLinus Torvalds 2934f3c7691eSJ. Bruce Fields return 0; 29357715b521SAl Viro } 29367715b521SAl Viro 2937e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 29387715b521SAl Viro { 2939f0bb5aafSAl Viro const struct path *path = &filp->f_path; 29407715b521SAl Viro struct inode *inode = path->dentry->d_inode; 29417715b521SAl Viro int error = get_write_access(inode); 29421da177e4SLinus Torvalds if (error) 29437715b521SAl Viro return error; 29441da177e4SLinus Torvalds /* 29451da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 29461da177e4SLinus Torvalds */ 2947d7a06983SJeff Layton error = locks_verify_locked(filp); 2948be6d3e56SKentaro Takeda if (!error) 2949ea0d3ab2STetsuo Handa error = security_path_truncate(path); 29501da177e4SLinus Torvalds if (!error) { 29517715b521SAl Viro error = do_truncate(path->dentry, 0, 2952d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2953e1181ee6SJeff Layton filp); 29541da177e4SLinus Torvalds } 29551da177e4SLinus Torvalds put_write_access(inode); 2956acd0c935SMimi Zohar return error; 29571da177e4SLinus Torvalds } 29581da177e4SLinus Torvalds 2959d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2960d57999e1SDave Hansen { 29618a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29628a5e929dSAl Viro flag--; 2963d57999e1SDave Hansen return flag; 2964d57999e1SDave Hansen } 2965d57999e1SDave Hansen 2966d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2967d18e9008SMiklos Szeredi { 29681328c727SSeth Forshee struct user_namespace *s_user_ns; 2969d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2970d18e9008SMiklos Szeredi if (error) 2971d18e9008SMiklos Szeredi return error; 2972d18e9008SMiklos Szeredi 29731328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29741328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29751328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29761328c727SSeth Forshee return -EOVERFLOW; 29771328c727SSeth Forshee 2978d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2979d18e9008SMiklos Szeredi if (error) 2980d18e9008SMiklos Szeredi return error; 2981d18e9008SMiklos Szeredi 2982d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2983d18e9008SMiklos Szeredi } 2984d18e9008SMiklos Szeredi 29851acf0af9SDavid Howells /* 29861acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29871acf0af9SDavid Howells * dentry. 29881acf0af9SDavid Howells * 29891acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29901acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29911acf0af9SDavid Howells * 29921acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 29931acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 29941acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 29951acf0af9SDavid Howells * 29961acf0af9SDavid Howells * Returns an error code otherwise. 29971acf0af9SDavid Howells */ 29982675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 299930d90494SAl Viro struct path *path, struct file *file, 3000015c3bbcSMiklos Szeredi const struct open_flags *op, 30011643b43fSAl Viro int open_flag, umode_t mode, 300247237687SAl Viro int *opened) 3003d18e9008SMiklos Szeredi { 3004d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 3005d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 3006d18e9008SMiklos Szeredi int error; 3007d18e9008SMiklos Szeredi 3008384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 3009d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 3010d18e9008SMiklos Szeredi 3011d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 3012d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 3013d18e9008SMiklos Szeredi 301430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 301530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 30160fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 30170fb1ea09SAl Viro open_to_namei_flags(open_flag), 30180fb1ea09SAl Viro mode, opened); 30196fbd0714SAl Viro d_lookup_done(dentry); 3020384f26e2SAl Viro if (!error) { 3021d18e9008SMiklos Szeredi /* 3022384f26e2SAl Viro * We didn't have the inode before the open, so check open 3023384f26e2SAl Viro * permission here. 3024d18e9008SMiklos Szeredi */ 3025384f26e2SAl Viro int acc_mode = op->acc_mode; 302603da633aSAl Viro if (*opened & FILE_CREATED) { 302703da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 302803da633aSAl Viro fsnotify_create(dir, dentry); 302962fb4a15SAl Viro acc_mode = 0; 303003da633aSAl Viro } 30312675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 3032384f26e2SAl Viro if (WARN_ON(error > 0)) 3033384f26e2SAl Viro error = -EINVAL; 3034384f26e2SAl Viro } else if (error > 0) { 3035d18e9008SMiklos Szeredi if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 3036d18e9008SMiklos Szeredi error = -EIO; 3037384f26e2SAl Viro } else { 3038d18e9008SMiklos Szeredi if (file->f_path.dentry) { 3039d18e9008SMiklos Szeredi dput(dentry); 3040d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 304110c64ceaSAl Viro } 3042d18e9008SMiklos Szeredi if (*opened & FILE_CREATED) 3043d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 3044a01e718fSAl Viro if (unlikely(d_is_negative(dentry))) { 3045a01e718fSAl Viro error = -ENOENT; 3046a01e718fSAl Viro } else { 3047d18e9008SMiklos Szeredi path->dentry = dentry; 3048d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 30492675a4ebSAl Viro return 1; 3050d18e9008SMiklos Szeredi } 3051d18e9008SMiklos Szeredi } 3052a01e718fSAl Viro } 3053d18e9008SMiklos Szeredi dput(dentry); 3054d18e9008SMiklos Szeredi return error; 3055d18e9008SMiklos Szeredi } 3056d18e9008SMiklos Szeredi 305731e6b01fSNick Piggin /* 30581acf0af9SDavid Howells * Look up and maybe create and open the last component. 3059d58ffd35SMiklos Szeredi * 3060d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 3061d58ffd35SMiklos Szeredi * 30621acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 30631acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 30641acf0af9SDavid Howells * 30651acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 30661acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 30671acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 30681acf0af9SDavid Howells * specified then a negative dentry may be returned. 30691acf0af9SDavid Howells * 30701acf0af9SDavid Howells * An error code is returned otherwise. 30711acf0af9SDavid Howells * 30721acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 30731acf0af9SDavid Howells * cleared otherwise prior to returning. 3074d58ffd35SMiklos Szeredi */ 30752675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 307630d90494SAl Viro struct file *file, 3077d58ffd35SMiklos Szeredi const struct open_flags *op, 307864894cf8SAl Viro bool got_write, int *opened) 3079d58ffd35SMiklos Szeredi { 3080d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 308154ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30821643b43fSAl Viro int open_flag = op->open_flag; 3083d58ffd35SMiklos Szeredi struct dentry *dentry; 30841643b43fSAl Viro int error, create_error = 0; 30851643b43fSAl Viro umode_t mode = op->mode; 30866fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3087d58ffd35SMiklos Szeredi 3088ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3089ce8644fcSAl Viro return -ENOENT; 3090d58ffd35SMiklos Szeredi 309147237687SAl Viro *opened &= ~FILE_CREATED; 30926fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30936fbd0714SAl Viro for (;;) { 30946fbd0714SAl Viro if (!dentry) { 30956fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3096d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 30972675a4ebSAl Viro return PTR_ERR(dentry); 30986fbd0714SAl Viro } 30996fbd0714SAl Viro if (d_in_lookup(dentry)) 31006fbd0714SAl Viro break; 3101d58ffd35SMiklos Szeredi 31026fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 31036fbd0714SAl Viro if (likely(error > 0)) 31046fbd0714SAl Viro break; 31056fbd0714SAl Viro if (error) 31066fbd0714SAl Viro goto out_dput; 31076fbd0714SAl Viro d_invalidate(dentry); 31086fbd0714SAl Viro dput(dentry); 31096fbd0714SAl Viro dentry = NULL; 31106fbd0714SAl Viro } 31116fbd0714SAl Viro if (dentry->d_inode) { 3112d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3113d18e9008SMiklos Szeredi goto out_no_open; 31146c51e513SAl Viro } 3115d18e9008SMiklos Szeredi 31161643b43fSAl Viro /* 31171643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 31181643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 31191643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 31201643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 31211643b43fSAl Viro * 31221643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 31231643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 31241643b43fSAl Viro */ 31251643b43fSAl Viro if (open_flag & O_CREAT) { 31261643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 31271643b43fSAl Viro mode &= ~current_umask(); 31281643b43fSAl Viro if (unlikely(!got_write)) { 31291643b43fSAl Viro create_error = -EROFS; 31301643b43fSAl Viro open_flag &= ~O_CREAT; 31311643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 31321643b43fSAl Viro goto no_open; 31331643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 31341643b43fSAl Viro } else { 31351643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 31361643b43fSAl Viro if (create_error) { 31371643b43fSAl Viro open_flag &= ~O_CREAT; 31381643b43fSAl Viro if (open_flag & O_EXCL) 31391643b43fSAl Viro goto no_open; 31401643b43fSAl Viro } 31411643b43fSAl Viro } 31421643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 31431643b43fSAl Viro unlikely(!got_write)) { 31441643b43fSAl Viro /* 31451643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 31461643b43fSAl Viro * back to lookup + open 31471643b43fSAl Viro */ 31481643b43fSAl Viro goto no_open; 3149d18e9008SMiklos Szeredi } 3150d18e9008SMiklos Szeredi 31511643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 31521643b43fSAl Viro error = atomic_open(nd, dentry, path, file, op, open_flag, 31531643b43fSAl Viro mode, opened); 31541643b43fSAl Viro if (unlikely(error == -ENOENT) && create_error) 31551643b43fSAl Viro error = create_error; 31561643b43fSAl Viro return error; 31571643b43fSAl Viro } 315854ef4872SMiklos Szeredi 31591643b43fSAl Viro no_open: 31606fbd0714SAl Viro if (d_in_lookup(dentry)) { 316112fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 316212fa5e24SAl Viro nd->flags); 31636fbd0714SAl Viro d_lookup_done(dentry); 316412fa5e24SAl Viro if (unlikely(res)) { 316512fa5e24SAl Viro if (IS_ERR(res)) { 316612fa5e24SAl Viro error = PTR_ERR(res); 316712fa5e24SAl Viro goto out_dput; 316812fa5e24SAl Viro } 316912fa5e24SAl Viro dput(dentry); 317012fa5e24SAl Viro dentry = res; 317112fa5e24SAl Viro } 317254ef4872SMiklos Szeredi } 317354ef4872SMiklos Szeredi 3174d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31751643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 317647237687SAl Viro *opened |= FILE_CREATED; 3177ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3178ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3179ce8644fcSAl Viro error = -EACCES; 3180d58ffd35SMiklos Szeredi goto out_dput; 318177d660a8SMiklos Szeredi } 3182ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31831643b43fSAl Viro open_flag & O_EXCL); 3184d58ffd35SMiklos Szeredi if (error) 3185d58ffd35SMiklos Szeredi goto out_dput; 3186ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3187d58ffd35SMiklos Szeredi } 31881643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31891643b43fSAl Viro error = create_error; 3190d58ffd35SMiklos Szeredi goto out_dput; 3191d58ffd35SMiklos Szeredi } 3192d18e9008SMiklos Szeredi out_no_open: 3193d58ffd35SMiklos Szeredi path->dentry = dentry; 3194d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 31952675a4ebSAl Viro return 1; 3196d58ffd35SMiklos Szeredi 3197d58ffd35SMiklos Szeredi out_dput: 3198d58ffd35SMiklos Szeredi dput(dentry); 31992675a4ebSAl Viro return error; 3200d58ffd35SMiklos Szeredi } 3201d58ffd35SMiklos Szeredi 3202d58ffd35SMiklos Szeredi /* 3203fe2d35ffSAl Viro * Handle the last step of open() 320431e6b01fSNick Piggin */ 3205896475d5SAl Viro static int do_last(struct nameidata *nd, 320630d90494SAl Viro struct file *file, const struct open_flags *op, 320776ae2a5aSAl Viro int *opened) 3208fb1cc555SAl Viro { 3209a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3210ca344a89SAl Viro int open_flag = op->open_flag; 321177d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 321264894cf8SAl Viro bool got_write = false; 3213bcda7652SAl Viro int acc_mode = op->acc_mode; 3214254cf582SAl Viro unsigned seq; 3215a1eb3315SMiklos Szeredi struct inode *inode; 3216896475d5SAl Viro struct path path; 321716c2cd71SAl Viro int error; 3218fb1cc555SAl Viro 3219c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 3220c3e380b0SAl Viro nd->flags |= op->intent; 3221c3e380b0SAl Viro 3222bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 3223fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3224deb106c6SAl Viro if (unlikely(error)) 32252675a4ebSAl Viro return error; 3226e83db167SMiklos Szeredi goto finish_open; 32271f36f774SAl Viro } 3228a2c36b45SAl Viro 3229ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3230fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3231fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3232fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 3233254cf582SAl Viro error = lookup_fast(nd, &path, &inode, &seq); 3234e9742b53SAl Viro if (likely(error > 0)) 323571574865SMiklos Szeredi goto finish_lookup; 323671574865SMiklos Szeredi 3237ce57dfc1SAl Viro if (error < 0) 3238deb106c6SAl Viro return error; 3239a1eb3315SMiklos Szeredi 324037d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 32416583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3242b6183df7SMiklos Szeredi } else { 3243fe2d35ffSAl Viro /* create side of things */ 3244a3fbbde7SAl Viro /* 3245b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3246b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3247b6183df7SMiklos Szeredi * about to look up 3248a3fbbde7SAl Viro */ 32499f1fafeeSAl Viro error = complete_walk(nd); 3250e8bb73dfSAl Viro if (error) 32512675a4ebSAl Viro return error; 3252fe2d35ffSAl Viro 325376ae2a5aSAl Viro audit_inode(nd->name, dir, LOOKUP_PARENT); 32541f36f774SAl Viro /* trailing slashes? */ 3255deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 3256deb106c6SAl Viro return -EISDIR; 3257b6183df7SMiklos Szeredi } 32581f36f774SAl Viro 32599cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 326064894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 326164894cf8SAl Viro if (!error) 326264894cf8SAl Viro got_write = true; 326364894cf8SAl Viro /* 326464894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 326564894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 326664894cf8SAl Viro * dropping this one anyway. 326764894cf8SAl Viro */ 326864894cf8SAl Viro } 32699cf843e3SAl Viro if (open_flag & O_CREAT) 32705955102cSAl Viro inode_lock(dir->d_inode); 32719cf843e3SAl Viro else 32729cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3273896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 32749cf843e3SAl Viro if (open_flag & O_CREAT) 32755955102cSAl Viro inode_unlock(dir->d_inode); 32769cf843e3SAl Viro else 32779cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3278fb1cc555SAl Viro 32792675a4ebSAl Viro if (error <= 0) { 32802675a4ebSAl Viro if (error) 3281d58ffd35SMiklos Szeredi goto out; 32826c0d46c4SAl Viro 328347237687SAl Viro if ((*opened & FILE_CREATED) || 3284496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 328577d660a8SMiklos Szeredi will_truncate = false; 3286d18e9008SMiklos Szeredi 328776ae2a5aSAl Viro audit_inode(nd->name, file->f_path.dentry, 0); 3288d18e9008SMiklos Szeredi goto opened; 3289d18e9008SMiklos Szeredi } 3290d18e9008SMiklos Szeredi 329147237687SAl Viro if (*opened & FILE_CREATED) { 32929b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3293ca344a89SAl Viro open_flag &= ~O_TRUNC; 329477d660a8SMiklos Szeredi will_truncate = false; 329562fb4a15SAl Viro acc_mode = 0; 3296896475d5SAl Viro path_to_nameidata(&path, nd); 3297e83db167SMiklos Szeredi goto finish_open_created; 3298fb1cc555SAl Viro } 3299fb1cc555SAl Viro 3300fb1cc555SAl Viro /* 3301d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3302d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3303d18e9008SMiklos Szeredi * necessary...) 3304d18e9008SMiklos Szeredi */ 330564894cf8SAl Viro if (got_write) { 3306d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 330764894cf8SAl Viro got_write = false; 3308d18e9008SMiklos Szeredi } 3309d18e9008SMiklos Szeredi 3310e6ec03a2SAl Viro error = follow_managed(&path, nd); 3311e6ec03a2SAl Viro if (unlikely(error < 0)) 3312e6ec03a2SAl Viro return error; 3313e6ec03a2SAl Viro 33146583fe22SAl Viro if (unlikely(d_is_negative(path.dentry))) { 33156583fe22SAl Viro path_to_nameidata(&path, nd); 33166583fe22SAl Viro return -ENOENT; 33176583fe22SAl Viro } 33186583fe22SAl Viro 33196583fe22SAl Viro /* 33206583fe22SAl Viro * create/update audit record if it already exists. 33216583fe22SAl Viro */ 33226583fe22SAl Viro audit_inode(nd->name, path.dentry, 0); 33236583fe22SAl Viro 3324deb106c6SAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 3325deb106c6SAl Viro path_to_nameidata(&path, nd); 3326deb106c6SAl Viro return -EEXIST; 3327deb106c6SAl Viro } 3328fb1cc555SAl Viro 3329254cf582SAl Viro seq = 0; /* out of RCU mode, so the value doesn't matter */ 3330d4565649SAl Viro inode = d_backing_inode(path.dentry); 3331766c4cbfSAl Viro finish_lookup: 33328f64fb1cSAl Viro error = step_into(nd, &path, 0, inode, seq); 3333deb106c6SAl Viro if (unlikely(error)) 3334d63ff28fSAl Viro return error; 3335bc77daa7SAl Viro finish_open: 33368f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3337a3fbbde7SAl Viro error = complete_walk(nd); 3338fac7d191SAl Viro if (error) 33392675a4ebSAl Viro return error; 334076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 3341fb1cc555SAl Viro error = -EISDIR; 334244b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 33432675a4ebSAl Viro goto out; 3344af2f5542SMiklos Szeredi error = -ENOTDIR; 334544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 33462675a4ebSAl Viro goto out; 33474bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 334877d660a8SMiklos Szeredi will_truncate = false; 33496c0d46c4SAl Viro 33500f9d1a10SAl Viro if (will_truncate) { 33510f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 33520f9d1a10SAl Viro if (error) 33532675a4ebSAl Viro goto out; 335464894cf8SAl Viro got_write = true; 33550f9d1a10SAl Viro } 3356e83db167SMiklos Szeredi finish_open_created: 3357bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3358ca344a89SAl Viro if (error) 33592675a4ebSAl Viro goto out; 33604aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 33614aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 3362fac7d191SAl Viro if (error) 3363015c3bbcSMiklos Szeredi goto out; 3364fac7d191SAl Viro *opened |= FILE_OPENED; 3365a8277b9bSMiklos Szeredi opened: 33662675a4ebSAl Viro error = open_check_o_direct(file); 3367fe9ec829SAl Viro if (!error) 33683034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3369fe9ec829SAl Viro if (!error && will_truncate) 33702675a4ebSAl Viro error = handle_truncate(file); 3371ca344a89SAl Viro out: 3372fe9ec829SAl Viro if (unlikely(error) && (*opened & FILE_OPENED)) 3373fe9ec829SAl Viro fput(file); 3374c80567c8SAl Viro if (unlikely(error > 0)) { 3375c80567c8SAl Viro WARN_ON(1); 3376c80567c8SAl Viro error = -EINVAL; 3377c80567c8SAl Viro } 337864894cf8SAl Viro if (got_write) 33790f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 33802675a4ebSAl Viro return error; 3381fb1cc555SAl Viro } 3382fb1cc555SAl Viro 3383af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3384af7bd4dcSAmir Goldstein { 3385af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3386af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3387af7bd4dcSAmir Goldstein struct inode *inode; 3388af7bd4dcSAmir Goldstein int error; 3389af7bd4dcSAmir Goldstein 3390af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3391af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3392af7bd4dcSAmir Goldstein if (error) 3393af7bd4dcSAmir Goldstein goto out_err; 3394af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3395af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3396af7bd4dcSAmir Goldstein goto out_err; 3397af7bd4dcSAmir Goldstein error = -ENOMEM; 3398cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3399af7bd4dcSAmir Goldstein if (unlikely(!child)) 3400af7bd4dcSAmir Goldstein goto out_err; 3401af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3402af7bd4dcSAmir Goldstein if (error) 3403af7bd4dcSAmir Goldstein goto out_err; 3404af7bd4dcSAmir Goldstein error = -ENOENT; 3405af7bd4dcSAmir Goldstein inode = child->d_inode; 3406af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3407af7bd4dcSAmir Goldstein goto out_err; 3408af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3409af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3410af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3411af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3412af7bd4dcSAmir Goldstein } 3413af7bd4dcSAmir Goldstein return child; 3414af7bd4dcSAmir Goldstein 3415af7bd4dcSAmir Goldstein out_err: 3416af7bd4dcSAmir Goldstein dput(child); 3417af7bd4dcSAmir Goldstein return ERR_PTR(error); 3418af7bd4dcSAmir Goldstein } 3419af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3420af7bd4dcSAmir Goldstein 3421c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 342260545d0dSAl Viro const struct open_flags *op, 342360545d0dSAl Viro struct file *file, int *opened) 342460545d0dSAl Viro { 3425625b6d10SAl Viro struct dentry *child; 3426625b6d10SAl Viro struct path path; 3427c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 342860545d0dSAl Viro if (unlikely(error)) 342960545d0dSAl Viro return error; 3430625b6d10SAl Viro error = mnt_want_write(path.mnt); 343160545d0dSAl Viro if (unlikely(error)) 343260545d0dSAl Viro goto out; 3433af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3434af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3435684e73beSHirofumi Nakagawa if (IS_ERR(child)) 343660545d0dSAl Viro goto out2; 3437625b6d10SAl Viro dput(path.dentry); 3438625b6d10SAl Viro path.dentry = child; 3439c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 344069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 344162fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 344260545d0dSAl Viro if (error) 344360545d0dSAl Viro goto out2; 3444625b6d10SAl Viro file->f_path.mnt = path.mnt; 3445625b6d10SAl Viro error = finish_open(file, child, NULL, opened); 344660545d0dSAl Viro if (error) 344760545d0dSAl Viro goto out2; 344860545d0dSAl Viro error = open_check_o_direct(file); 3449af7bd4dcSAmir Goldstein if (error) 345060545d0dSAl Viro fput(file); 345160545d0dSAl Viro out2: 3452625b6d10SAl Viro mnt_drop_write(path.mnt); 345360545d0dSAl Viro out: 3454625b6d10SAl Viro path_put(&path); 345560545d0dSAl Viro return error; 345660545d0dSAl Viro } 345760545d0dSAl Viro 34586ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 34596ac08709SAl Viro { 34606ac08709SAl Viro struct path path; 34616ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 34626ac08709SAl Viro if (!error) { 34636ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 34646ac08709SAl Viro error = vfs_open(&path, file, current_cred()); 34656ac08709SAl Viro path_put(&path); 34666ac08709SAl Viro } 34676ac08709SAl Viro return error; 34686ac08709SAl Viro } 34696ac08709SAl Viro 3470c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3471c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 34721da177e4SLinus Torvalds { 3473368ee9baSAl Viro const char *s; 347430d90494SAl Viro struct file *file; 347547237687SAl Viro int opened = 0; 347613aab428SAl Viro int error; 347731e6b01fSNick Piggin 347830d90494SAl Viro file = get_empty_filp(); 34791afc99beSAl Viro if (IS_ERR(file)) 34801afc99beSAl Viro return file; 348131e6b01fSNick Piggin 348230d90494SAl Viro file->f_flags = op->open_flag; 348331e6b01fSNick Piggin 3484bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 3485c8a53ee5SAl Viro error = do_tmpfile(nd, flags, op, file, &opened); 3486f15133dfSAl Viro goto out2; 348760545d0dSAl Viro } 348860545d0dSAl Viro 34896ac08709SAl Viro if (unlikely(file->f_flags & O_PATH)) { 34906ac08709SAl Viro error = do_o_path(nd, flags, file); 34916ac08709SAl Viro if (!error) 34926ac08709SAl Viro opened |= FILE_OPENED; 34936ac08709SAl Viro goto out2; 34946ac08709SAl Viro } 34956ac08709SAl Viro 3496c8a53ee5SAl Viro s = path_init(nd, flags); 3497368ee9baSAl Viro if (IS_ERR(s)) { 3498368ee9baSAl Viro put_filp(file); 3499368ee9baSAl Viro return ERR_CAST(s); 3500368ee9baSAl Viro } 35013bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 350276ae2a5aSAl Viro (error = do_last(nd, file, op, &opened)) > 0) { 350373d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 35043bdba28bSAl Viro s = trailing_symlink(nd); 35053bdba28bSAl Viro if (IS_ERR(s)) { 35063bdba28bSAl Viro error = PTR_ERR(s); 35072675a4ebSAl Viro break; 3508806b681cSAl Viro } 35093bdba28bSAl Viro } 3510deb106c6SAl Viro terminate_walk(nd); 3511f15133dfSAl Viro out2: 35122675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 35132675a4ebSAl Viro BUG_ON(!error); 351430d90494SAl Viro put_filp(file); 3515015c3bbcSMiklos Szeredi } 35162675a4ebSAl Viro if (unlikely(error)) { 35172675a4ebSAl Viro if (error == -EOPENSTALE) { 35182675a4ebSAl Viro if (flags & LOOKUP_RCU) 35192675a4ebSAl Viro error = -ECHILD; 35202675a4ebSAl Viro else 35212675a4ebSAl Viro error = -ESTALE; 35222675a4ebSAl Viro } 35232675a4ebSAl Viro file = ERR_PTR(error); 35242675a4ebSAl Viro } 35252675a4ebSAl Viro return file; 3526de459215SKirill Korotaev } 35271da177e4SLinus Torvalds 3528669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3529f9652e10SAl Viro const struct open_flags *op) 353013aab428SAl Viro { 35319883d185SAl Viro struct nameidata nd; 3532f9652e10SAl Viro int flags = op->lookup_flags; 353313aab428SAl Viro struct file *filp; 353413aab428SAl Viro 35359883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3536c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 353713aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3538c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 353913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3540c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 35419883d185SAl Viro restore_nameidata(); 354213aab428SAl Viro return filp; 354313aab428SAl Viro } 354413aab428SAl Viro 354573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3546f9652e10SAl Viro const char *name, const struct open_flags *op) 354773d049a4SAl Viro { 35489883d185SAl Viro struct nameidata nd; 354973d049a4SAl Viro struct file *file; 355051689104SPaul Moore struct filename *filename; 3551f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 355273d049a4SAl Viro 355373d049a4SAl Viro nd.root.mnt = mnt; 355473d049a4SAl Viro nd.root.dentry = dentry; 355573d049a4SAl Viro 3556b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 355773d049a4SAl Viro return ERR_PTR(-ELOOP); 355873d049a4SAl Viro 355951689104SPaul Moore filename = getname_kernel(name); 3560a1c83681SViresh Kumar if (IS_ERR(filename)) 356151689104SPaul Moore return ERR_CAST(filename); 356251689104SPaul Moore 35639883d185SAl Viro set_nameidata(&nd, -1, filename); 3564c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 356573d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3566c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 356773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3568c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 35699883d185SAl Viro restore_nameidata(); 357051689104SPaul Moore putname(filename); 357173d049a4SAl Viro return file; 357273d049a4SAl Viro } 357373d049a4SAl Viro 3574fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 35751ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 35761da177e4SLinus Torvalds { 3577c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3578391172c4SAl Viro struct qstr last; 3579391172c4SAl Viro int type; 3580c30dabfeSJan Kara int err2; 35811ac12b4bSJeff Layton int error; 35821ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 35831ac12b4bSJeff Layton 35841ac12b4bSJeff Layton /* 35851ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 35861ac12b4bSJeff Layton * other flags passed in are ignored! 35871ac12b4bSJeff Layton */ 35881ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 35891ac12b4bSJeff Layton 35905c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 35915c31b6ceSAl Viro if (IS_ERR(name)) 35925c31b6ceSAl Viro return ERR_CAST(name); 35931da177e4SLinus Torvalds 3594c663e5d8SChristoph Hellwig /* 3595c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3596c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3597c663e5d8SChristoph Hellwig */ 35985c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3599ed75e95dSAl Viro goto out; 3600c663e5d8SChristoph Hellwig 3601c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3602391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3603c663e5d8SChristoph Hellwig /* 3604c663e5d8SChristoph Hellwig * Do the final lookup. 3605c663e5d8SChristoph Hellwig */ 3606391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 36075955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3608391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 36091da177e4SLinus Torvalds if (IS_ERR(dentry)) 3610a8104a9fSAl Viro goto unlock; 3611c663e5d8SChristoph Hellwig 3612a8104a9fSAl Viro error = -EEXIST; 3613b18825a7SDavid Howells if (d_is_positive(dentry)) 3614a8104a9fSAl Viro goto fail; 3615b18825a7SDavid Howells 3616c663e5d8SChristoph Hellwig /* 3617c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3618c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3619c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3620c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3621c663e5d8SChristoph Hellwig */ 3622391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3623a8104a9fSAl Viro error = -ENOENT; 3624ed75e95dSAl Viro goto fail; 3625e9baf6e5SAl Viro } 3626c30dabfeSJan Kara if (unlikely(err2)) { 3627c30dabfeSJan Kara error = err2; 3628a8104a9fSAl Viro goto fail; 3629c30dabfeSJan Kara } 3630181c37b6SAl Viro putname(name); 3631e9baf6e5SAl Viro return dentry; 36321da177e4SLinus Torvalds fail: 3633a8104a9fSAl Viro dput(dentry); 3634a8104a9fSAl Viro dentry = ERR_PTR(error); 3635a8104a9fSAl Viro unlock: 36365955102cSAl Viro inode_unlock(path->dentry->d_inode); 3637c30dabfeSJan Kara if (!err2) 3638391172c4SAl Viro mnt_drop_write(path->mnt); 3639ed75e95dSAl Viro out: 3640391172c4SAl Viro path_put(path); 3641181c37b6SAl Viro putname(name); 3642ed75e95dSAl Viro return dentry; 3643dae6ad8fSAl Viro } 3644fa14a0b8SAl Viro 3645fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3646fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3647fa14a0b8SAl Viro { 3648181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3649181c37b6SAl Viro path, lookup_flags); 3650fa14a0b8SAl Viro } 3651dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3652dae6ad8fSAl Viro 3653921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3654921a1650SAl Viro { 3655921a1650SAl Viro dput(dentry); 36565955102cSAl Viro inode_unlock(path->dentry->d_inode); 3657a8104a9fSAl Viro mnt_drop_write(path->mnt); 3658921a1650SAl Viro path_put(path); 3659921a1650SAl Viro } 3660921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3661921a1650SAl Viro 3662520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 36631ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3664dae6ad8fSAl Viro { 3665181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3666dae6ad8fSAl Viro } 3667dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3668dae6ad8fSAl Viro 36691a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 36701da177e4SLinus Torvalds { 3671a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36721da177e4SLinus Torvalds 36731da177e4SLinus Torvalds if (error) 36741da177e4SLinus Torvalds return error; 36751da177e4SLinus Torvalds 3676975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 36771da177e4SLinus Torvalds return -EPERM; 36781da177e4SLinus Torvalds 3679acfa4380SAl Viro if (!dir->i_op->mknod) 36801da177e4SLinus Torvalds return -EPERM; 36811da177e4SLinus Torvalds 368208ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 368308ce5f16SSerge E. Hallyn if (error) 368408ce5f16SSerge E. Hallyn return error; 368508ce5f16SSerge E. Hallyn 36861da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 36871da177e4SLinus Torvalds if (error) 36881da177e4SLinus Torvalds return error; 36891da177e4SLinus Torvalds 36901da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3691a74574aaSStephen Smalley if (!error) 3692f38aa942SAmy Griffis fsnotify_create(dir, dentry); 36931da177e4SLinus Torvalds return error; 36941da177e4SLinus Torvalds } 36954d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 36961da177e4SLinus Torvalds 3697f69aac00SAl Viro static int may_mknod(umode_t mode) 3698463c3197SDave Hansen { 3699463c3197SDave Hansen switch (mode & S_IFMT) { 3700463c3197SDave Hansen case S_IFREG: 3701463c3197SDave Hansen case S_IFCHR: 3702463c3197SDave Hansen case S_IFBLK: 3703463c3197SDave Hansen case S_IFIFO: 3704463c3197SDave Hansen case S_IFSOCK: 3705463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3706463c3197SDave Hansen return 0; 3707463c3197SDave Hansen case S_IFDIR: 3708463c3197SDave Hansen return -EPERM; 3709463c3197SDave Hansen default: 3710463c3197SDave Hansen return -EINVAL; 3711463c3197SDave Hansen } 3712463c3197SDave Hansen } 3713463c3197SDave Hansen 37148208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 37152e4d0924SHeiko Carstens unsigned, dev) 37161da177e4SLinus Torvalds { 37171da177e4SLinus Torvalds struct dentry *dentry; 3718dae6ad8fSAl Viro struct path path; 3719dae6ad8fSAl Viro int error; 3720972567f1SJeff Layton unsigned int lookup_flags = 0; 37211da177e4SLinus Torvalds 37228e4bfca1SAl Viro error = may_mknod(mode); 37238e4bfca1SAl Viro if (error) 37248e4bfca1SAl Viro return error; 3725972567f1SJeff Layton retry: 3726972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3727dae6ad8fSAl Viro if (IS_ERR(dentry)) 3728dae6ad8fSAl Viro return PTR_ERR(dentry); 37292ad94ae6SAl Viro 3730dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3731ce3b0f8dSAl Viro mode &= ~current_umask(); 3732dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3733be6d3e56SKentaro Takeda if (error) 3734a8104a9fSAl Viro goto out; 37351da177e4SLinus Torvalds switch (mode & S_IFMT) { 37361da177e4SLinus Torvalds case 0: case S_IFREG: 3737312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 373805d1a717SMimi Zohar if (!error) 373905d1a717SMimi Zohar ima_post_path_mknod(dentry); 37401da177e4SLinus Torvalds break; 37411da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3742dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 37431da177e4SLinus Torvalds new_decode_dev(dev)); 37441da177e4SLinus Torvalds break; 37451da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3746dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 37471da177e4SLinus Torvalds break; 37481da177e4SLinus Torvalds } 3749a8104a9fSAl Viro out: 3750921a1650SAl Viro done_path_create(&path, dentry); 3751972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3752972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3753972567f1SJeff Layton goto retry; 3754972567f1SJeff Layton } 37551da177e4SLinus Torvalds return error; 37561da177e4SLinus Torvalds } 37571da177e4SLinus Torvalds 37588208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 37595590ff0dSUlrich Drepper { 37605590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 37615590ff0dSUlrich Drepper } 37625590ff0dSUlrich Drepper 376318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 37641da177e4SLinus Torvalds { 3765a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 37668de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 37671da177e4SLinus Torvalds 37681da177e4SLinus Torvalds if (error) 37691da177e4SLinus Torvalds return error; 37701da177e4SLinus Torvalds 3771acfa4380SAl Viro if (!dir->i_op->mkdir) 37721da177e4SLinus Torvalds return -EPERM; 37731da177e4SLinus Torvalds 37741da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 37751da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 37761da177e4SLinus Torvalds if (error) 37771da177e4SLinus Torvalds return error; 37781da177e4SLinus Torvalds 37798de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 37808de52778SAl Viro return -EMLINK; 37818de52778SAl Viro 37821da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3783a74574aaSStephen Smalley if (!error) 3784f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 37851da177e4SLinus Torvalds return error; 37861da177e4SLinus Torvalds } 37874d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 37881da177e4SLinus Torvalds 3789a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37901da177e4SLinus Torvalds { 37916902d925SDave Hansen struct dentry *dentry; 3792dae6ad8fSAl Viro struct path path; 3793dae6ad8fSAl Viro int error; 3794b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 37951da177e4SLinus Torvalds 3796b76d8b82SJeff Layton retry: 3797b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 37986902d925SDave Hansen if (IS_ERR(dentry)) 3799dae6ad8fSAl Viro return PTR_ERR(dentry); 38006902d925SDave Hansen 3801dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3802ce3b0f8dSAl Viro mode &= ~current_umask(); 3803dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3804a8104a9fSAl Viro if (!error) 3805dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3806921a1650SAl Viro done_path_create(&path, dentry); 3807b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3808b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3809b76d8b82SJeff Layton goto retry; 3810b76d8b82SJeff Layton } 38111da177e4SLinus Torvalds return error; 38121da177e4SLinus Torvalds } 38131da177e4SLinus Torvalds 3814a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 38155590ff0dSUlrich Drepper { 38165590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 38175590ff0dSUlrich Drepper } 38185590ff0dSUlrich Drepper 38191da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 38201da177e4SLinus Torvalds { 38211da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 38221da177e4SLinus Torvalds 38231da177e4SLinus Torvalds if (error) 38241da177e4SLinus Torvalds return error; 38251da177e4SLinus Torvalds 3826acfa4380SAl Viro if (!dir->i_op->rmdir) 38271da177e4SLinus Torvalds return -EPERM; 38281da177e4SLinus Torvalds 38291d2ef590SAl Viro dget(dentry); 38305955102cSAl Viro inode_lock(dentry->d_inode); 3831912dbc15SSage Weil 38321da177e4SLinus Torvalds error = -EBUSY; 38337af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3834912dbc15SSage Weil goto out; 3835912dbc15SSage Weil 38361da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3837912dbc15SSage Weil if (error) 3838912dbc15SSage Weil goto out; 3839912dbc15SSage Weil 38403cebde24SSage Weil shrink_dcache_parent(dentry); 38411da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3842912dbc15SSage Weil if (error) 3843912dbc15SSage Weil goto out; 3844912dbc15SSage Weil 38451da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3846d83c49f3SAl Viro dont_mount(dentry); 38478ed936b5SEric W. Biederman detach_mounts(dentry); 38481da177e4SLinus Torvalds 3849912dbc15SSage Weil out: 38505955102cSAl Viro inode_unlock(dentry->d_inode); 38511d2ef590SAl Viro dput(dentry); 3852912dbc15SSage Weil if (!error) 3853912dbc15SSage Weil d_delete(dentry); 38541da177e4SLinus Torvalds return error; 38551da177e4SLinus Torvalds } 38564d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 38571da177e4SLinus Torvalds 38585590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 38591da177e4SLinus Torvalds { 38601da177e4SLinus Torvalds int error = 0; 386191a27b2aSJeff Layton struct filename *name; 38621da177e4SLinus Torvalds struct dentry *dentry; 3863f5beed75SAl Viro struct path path; 3864f5beed75SAl Viro struct qstr last; 3865f5beed75SAl Viro int type; 3866c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3867c6ee9206SJeff Layton retry: 3868c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3869c1d4dd27SAl Viro &path, &last, &type); 387091a27b2aSJeff Layton if (IS_ERR(name)) 387191a27b2aSJeff Layton return PTR_ERR(name); 38721da177e4SLinus Torvalds 3873f5beed75SAl Viro switch (type) { 38741da177e4SLinus Torvalds case LAST_DOTDOT: 38751da177e4SLinus Torvalds error = -ENOTEMPTY; 38761da177e4SLinus Torvalds goto exit1; 38771da177e4SLinus Torvalds case LAST_DOT: 38781da177e4SLinus Torvalds error = -EINVAL; 38791da177e4SLinus Torvalds goto exit1; 38801da177e4SLinus Torvalds case LAST_ROOT: 38811da177e4SLinus Torvalds error = -EBUSY; 38821da177e4SLinus Torvalds goto exit1; 38831da177e4SLinus Torvalds } 38840612d9fbSOGAWA Hirofumi 3885f5beed75SAl Viro error = mnt_want_write(path.mnt); 3886c30dabfeSJan Kara if (error) 3887c30dabfeSJan Kara goto exit1; 38880612d9fbSOGAWA Hirofumi 38895955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3890f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38911da177e4SLinus Torvalds error = PTR_ERR(dentry); 38926902d925SDave Hansen if (IS_ERR(dentry)) 38936902d925SDave Hansen goto exit2; 3894e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3895e6bc45d6STheodore Ts'o error = -ENOENT; 3896e6bc45d6STheodore Ts'o goto exit3; 3897e6bc45d6STheodore Ts'o } 3898f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3899be6d3e56SKentaro Takeda if (error) 3900c30dabfeSJan Kara goto exit3; 3901f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 39020622753bSDave Hansen exit3: 39031da177e4SLinus Torvalds dput(dentry); 39046902d925SDave Hansen exit2: 39055955102cSAl Viro inode_unlock(path.dentry->d_inode); 3906f5beed75SAl Viro mnt_drop_write(path.mnt); 39071da177e4SLinus Torvalds exit1: 3908f5beed75SAl Viro path_put(&path); 39091da177e4SLinus Torvalds putname(name); 3910c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3911c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3912c6ee9206SJeff Layton goto retry; 3913c6ee9206SJeff Layton } 39141da177e4SLinus Torvalds return error; 39151da177e4SLinus Torvalds } 39161da177e4SLinus Torvalds 39173cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 39185590ff0dSUlrich Drepper { 39195590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 39205590ff0dSUlrich Drepper } 39215590ff0dSUlrich Drepper 3922b21996e3SJ. Bruce Fields /** 3923b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3924b21996e3SJ. Bruce Fields * @dir: parent directory 3925b21996e3SJ. Bruce Fields * @dentry: victim 3926b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3927b21996e3SJ. Bruce Fields * 3928b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3929b21996e3SJ. Bruce Fields * 3930b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3931b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3932b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3933b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3934b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3935b21996e3SJ. Bruce Fields * 3936b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3937b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3938b21996e3SJ. Bruce Fields * to be NFS exported. 3939b21996e3SJ. Bruce Fields */ 3940b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 39411da177e4SLinus Torvalds { 39429accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 39431da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 39441da177e4SLinus Torvalds 39451da177e4SLinus Torvalds if (error) 39461da177e4SLinus Torvalds return error; 39471da177e4SLinus Torvalds 3948acfa4380SAl Viro if (!dir->i_op->unlink) 39491da177e4SLinus Torvalds return -EPERM; 39501da177e4SLinus Torvalds 39515955102cSAl Viro inode_lock(target); 39528ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 39531da177e4SLinus Torvalds error = -EBUSY; 39541da177e4SLinus Torvalds else { 39551da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3956bec1052eSAl Viro if (!error) { 39575a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 39585a14696cSJ. Bruce Fields if (error) 3959b21996e3SJ. Bruce Fields goto out; 39601da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 39618ed936b5SEric W. Biederman if (!error) { 3962d83c49f3SAl Viro dont_mount(dentry); 39638ed936b5SEric W. Biederman detach_mounts(dentry); 39648ed936b5SEric W. Biederman } 3965bec1052eSAl Viro } 39661da177e4SLinus Torvalds } 3967b21996e3SJ. Bruce Fields out: 39685955102cSAl Viro inode_unlock(target); 39691da177e4SLinus Torvalds 39701da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 39711da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 39729accbb97SJ. Bruce Fields fsnotify_link_count(target); 39731da177e4SLinus Torvalds d_delete(dentry); 39741da177e4SLinus Torvalds } 39750eeca283SRobert Love 39761da177e4SLinus Torvalds return error; 39771da177e4SLinus Torvalds } 39784d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 39791da177e4SLinus Torvalds 39801da177e4SLinus Torvalds /* 39811da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 39821b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 39831da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 39841da177e4SLinus Torvalds * while waiting on the I/O. 39851da177e4SLinus Torvalds */ 3986da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 39871da177e4SLinus Torvalds { 39882ad94ae6SAl Viro int error; 39891da177e4SLinus Torvalds struct dentry *dentry; 3990f5beed75SAl Viro struct path path; 3991f5beed75SAl Viro struct qstr last; 3992f5beed75SAl Viro int type; 39931da177e4SLinus Torvalds struct inode *inode = NULL; 3994b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 39955d18f813SJeff Layton unsigned int lookup_flags = 0; 39965d18f813SJeff Layton retry: 3997da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 399891a27b2aSJeff Layton if (IS_ERR(name)) 399991a27b2aSJeff Layton return PTR_ERR(name); 40002ad94ae6SAl Viro 40011da177e4SLinus Torvalds error = -EISDIR; 4002f5beed75SAl Viro if (type != LAST_NORM) 40031da177e4SLinus Torvalds goto exit1; 40040612d9fbSOGAWA Hirofumi 4005f5beed75SAl Viro error = mnt_want_write(path.mnt); 4006c30dabfeSJan Kara if (error) 4007c30dabfeSJan Kara goto exit1; 4008b21996e3SJ. Bruce Fields retry_deleg: 40095955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 4010f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 40111da177e4SLinus Torvalds error = PTR_ERR(dentry); 40121da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 40131da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 4014f5beed75SAl Viro if (last.name[last.len]) 401550338b88STörök Edwin goto slashes; 40161da177e4SLinus Torvalds inode = dentry->d_inode; 4017b18825a7SDavid Howells if (d_is_negative(dentry)) 4018e6bc45d6STheodore Ts'o goto slashes; 40197de9c6eeSAl Viro ihold(inode); 4020f5beed75SAl Viro error = security_path_unlink(&path, dentry); 4021be6d3e56SKentaro Takeda if (error) 4022c30dabfeSJan Kara goto exit2; 4023f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 40241da177e4SLinus Torvalds exit2: 40251da177e4SLinus Torvalds dput(dentry); 40261da177e4SLinus Torvalds } 40275955102cSAl Viro inode_unlock(path.dentry->d_inode); 40281da177e4SLinus Torvalds if (inode) 40291da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 4030b21996e3SJ. Bruce Fields inode = NULL; 4031b21996e3SJ. Bruce Fields if (delegated_inode) { 40325a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4033b21996e3SJ. Bruce Fields if (!error) 4034b21996e3SJ. Bruce Fields goto retry_deleg; 4035b21996e3SJ. Bruce Fields } 4036f5beed75SAl Viro mnt_drop_write(path.mnt); 40371da177e4SLinus Torvalds exit1: 4038f5beed75SAl Viro path_put(&path); 40395d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 40405d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 40415d18f813SJeff Layton inode = NULL; 40425d18f813SJeff Layton goto retry; 40435d18f813SJeff Layton } 4044da2f1362SChristoph Hellwig putname(name); 40451da177e4SLinus Torvalds return error; 40461da177e4SLinus Torvalds 40471da177e4SLinus Torvalds slashes: 4048b18825a7SDavid Howells if (d_is_negative(dentry)) 4049b18825a7SDavid Howells error = -ENOENT; 405044b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 4051b18825a7SDavid Howells error = -EISDIR; 4052b18825a7SDavid Howells else 4053b18825a7SDavid Howells error = -ENOTDIR; 40541da177e4SLinus Torvalds goto exit2; 40551da177e4SLinus Torvalds } 40561da177e4SLinus Torvalds 40572e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 40585590ff0dSUlrich Drepper { 40595590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 40605590ff0dSUlrich Drepper return -EINVAL; 40615590ff0dSUlrich Drepper 40625590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 40635590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 40645590ff0dSUlrich Drepper 4065da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 40665590ff0dSUlrich Drepper } 40675590ff0dSUlrich Drepper 40683480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 40695590ff0dSUlrich Drepper { 4070da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 40715590ff0dSUlrich Drepper } 40725590ff0dSUlrich Drepper 4073db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 40741da177e4SLinus Torvalds { 4075a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 40761da177e4SLinus Torvalds 40771da177e4SLinus Torvalds if (error) 40781da177e4SLinus Torvalds return error; 40791da177e4SLinus Torvalds 4080acfa4380SAl Viro if (!dir->i_op->symlink) 40811da177e4SLinus Torvalds return -EPERM; 40821da177e4SLinus Torvalds 40831da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 40841da177e4SLinus Torvalds if (error) 40851da177e4SLinus Torvalds return error; 40861da177e4SLinus Torvalds 40871da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 4088a74574aaSStephen Smalley if (!error) 4089f38aa942SAmy Griffis fsnotify_create(dir, dentry); 40901da177e4SLinus Torvalds return error; 40911da177e4SLinus Torvalds } 40924d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 40931da177e4SLinus Torvalds 40942e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 40952e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 40961da177e4SLinus Torvalds { 40972ad94ae6SAl Viro int error; 409891a27b2aSJeff Layton struct filename *from; 40996902d925SDave Hansen struct dentry *dentry; 4100dae6ad8fSAl Viro struct path path; 4101f46d3567SJeff Layton unsigned int lookup_flags = 0; 41021da177e4SLinus Torvalds 41031da177e4SLinus Torvalds from = getname(oldname); 41041da177e4SLinus Torvalds if (IS_ERR(from)) 41051da177e4SLinus Torvalds return PTR_ERR(from); 4106f46d3567SJeff Layton retry: 4107f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 41081da177e4SLinus Torvalds error = PTR_ERR(dentry); 41096902d925SDave Hansen if (IS_ERR(dentry)) 4110dae6ad8fSAl Viro goto out_putname; 41116902d925SDave Hansen 411291a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4113a8104a9fSAl Viro if (!error) 411491a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4115921a1650SAl Viro done_path_create(&path, dentry); 4116f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4117f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4118f46d3567SJeff Layton goto retry; 4119f46d3567SJeff Layton } 41206902d925SDave Hansen out_putname: 41211da177e4SLinus Torvalds putname(from); 41221da177e4SLinus Torvalds return error; 41231da177e4SLinus Torvalds } 41241da177e4SLinus Torvalds 41253480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 41265590ff0dSUlrich Drepper { 41275590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 41285590ff0dSUlrich Drepper } 41295590ff0dSUlrich Drepper 4130146a8595SJ. Bruce Fields /** 4131146a8595SJ. Bruce Fields * vfs_link - create a new link 4132146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4133146a8595SJ. Bruce Fields * @dir: new parent 4134146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4135146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4136146a8595SJ. Bruce Fields * 4137146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4138146a8595SJ. Bruce Fields * 4139146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4140146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4141146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4142146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4143146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4144146a8595SJ. Bruce Fields * 4145146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4146146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4147146a8595SJ. Bruce Fields * to be NFS exported. 4148146a8595SJ. Bruce Fields */ 4149146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 41501da177e4SLinus Torvalds { 41511da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 41528de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 41531da177e4SLinus Torvalds int error; 41541da177e4SLinus Torvalds 41551da177e4SLinus Torvalds if (!inode) 41561da177e4SLinus Torvalds return -ENOENT; 41571da177e4SLinus Torvalds 4158a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 41591da177e4SLinus Torvalds if (error) 41601da177e4SLinus Torvalds return error; 41611da177e4SLinus Torvalds 41621da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 41631da177e4SLinus Torvalds return -EXDEV; 41641da177e4SLinus Torvalds 41651da177e4SLinus Torvalds /* 41661da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 41671da177e4SLinus Torvalds */ 41681da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 41691da177e4SLinus Torvalds return -EPERM; 41700bd23d09SEric W. Biederman /* 41710bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 41720bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 41730bd23d09SEric W. Biederman * the vfs. 41740bd23d09SEric W. Biederman */ 41750bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 41760bd23d09SEric W. Biederman return -EPERM; 4177acfa4380SAl Viro if (!dir->i_op->link) 41781da177e4SLinus Torvalds return -EPERM; 41797e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 41801da177e4SLinus Torvalds return -EPERM; 41811da177e4SLinus Torvalds 41821da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 41831da177e4SLinus Torvalds if (error) 41841da177e4SLinus Torvalds return error; 41851da177e4SLinus Torvalds 41865955102cSAl Viro inode_lock(inode); 4187aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4188f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4189aae8a97dSAneesh Kumar K.V error = -ENOENT; 41908de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 41918de52778SAl Viro error = -EMLINK; 4192146a8595SJ. Bruce Fields else { 4193146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4194146a8595SJ. Bruce Fields if (!error) 41951da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4196146a8595SJ. Bruce Fields } 4197f4e0c30cSAl Viro 4198f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4199f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4200f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4201f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4202f4e0c30cSAl Viro } 42035955102cSAl Viro inode_unlock(inode); 4204e31e14ecSStephen Smalley if (!error) 42057e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 42061da177e4SLinus Torvalds return error; 42071da177e4SLinus Torvalds } 42084d359507SAl Viro EXPORT_SYMBOL(vfs_link); 42091da177e4SLinus Torvalds 42101da177e4SLinus Torvalds /* 42111da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 42121da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 42131da177e4SLinus Torvalds * newname. --KAB 42141da177e4SLinus Torvalds * 42151da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 42161da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 42171da177e4SLinus Torvalds * and other special files. --ADM 42181da177e4SLinus Torvalds */ 42192e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 42202e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 42211da177e4SLinus Torvalds { 42221da177e4SLinus Torvalds struct dentry *new_dentry; 4223dae6ad8fSAl Viro struct path old_path, new_path; 4224146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 422511a7b371SAneesh Kumar K.V int how = 0; 42261da177e4SLinus Torvalds int error; 42271da177e4SLinus Torvalds 422811a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4229c04030e1SUlrich Drepper return -EINVAL; 423011a7b371SAneesh Kumar K.V /* 4231f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4232f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4233f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 423411a7b371SAneesh Kumar K.V */ 4235f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4236f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4237f0cc6ffbSLinus Torvalds return -ENOENT; 423811a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4239f0cc6ffbSLinus Torvalds } 4240c04030e1SUlrich Drepper 424111a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 424211a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4243442e31caSJeff Layton retry: 424411a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 42451da177e4SLinus Torvalds if (error) 42462ad94ae6SAl Viro return error; 42472ad94ae6SAl Viro 4248442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4249442e31caSJeff Layton (how & LOOKUP_REVAL)); 42501da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 42516902d925SDave Hansen if (IS_ERR(new_dentry)) 4252dae6ad8fSAl Viro goto out; 4253dae6ad8fSAl Viro 4254dae6ad8fSAl Viro error = -EXDEV; 4255dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4256dae6ad8fSAl Viro goto out_dput; 4257800179c9SKees Cook error = may_linkat(&old_path); 4258800179c9SKees Cook if (unlikely(error)) 4259800179c9SKees Cook goto out_dput; 4260dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4261be6d3e56SKentaro Takeda if (error) 4262a8104a9fSAl Viro goto out_dput; 4263146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 426475c3f29dSDave Hansen out_dput: 4265921a1650SAl Viro done_path_create(&new_path, new_dentry); 4266146a8595SJ. Bruce Fields if (delegated_inode) { 4267146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4268d22e6338SOleg Drokin if (!error) { 4269d22e6338SOleg Drokin path_put(&old_path); 4270146a8595SJ. Bruce Fields goto retry; 4271146a8595SJ. Bruce Fields } 4272d22e6338SOleg Drokin } 4273442e31caSJeff Layton if (retry_estale(error, how)) { 4274d22e6338SOleg Drokin path_put(&old_path); 4275442e31caSJeff Layton how |= LOOKUP_REVAL; 4276442e31caSJeff Layton goto retry; 4277442e31caSJeff Layton } 42781da177e4SLinus Torvalds out: 42792d8f3038SAl Viro path_put(&old_path); 42801da177e4SLinus Torvalds 42811da177e4SLinus Torvalds return error; 42821da177e4SLinus Torvalds } 42831da177e4SLinus Torvalds 42843480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 42855590ff0dSUlrich Drepper { 4286c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 42875590ff0dSUlrich Drepper } 42885590ff0dSUlrich Drepper 4289bc27027aSMiklos Szeredi /** 4290bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4291bc27027aSMiklos Szeredi * @old_dir: parent of source 4292bc27027aSMiklos Szeredi * @old_dentry: source 4293bc27027aSMiklos Szeredi * @new_dir: parent of destination 4294bc27027aSMiklos Szeredi * @new_dentry: destination 4295bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4296520c8b16SMiklos Szeredi * @flags: rename flags 4297bc27027aSMiklos Szeredi * 4298bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4299bc27027aSMiklos Szeredi * 4300bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4301bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4302bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4303bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4304bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4305bc27027aSMiklos Szeredi * so. 4306bc27027aSMiklos Szeredi * 4307bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4308bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4309bc27027aSMiklos Szeredi * to be NFS exported. 4310bc27027aSMiklos Szeredi * 43111da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 43121da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 43131da177e4SLinus Torvalds * Problems: 43140117d427SMauro Carvalho Chehab * 4315d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 43161da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 43171da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4318a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 43191da177e4SLinus Torvalds * story. 43206cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 43216cedba89SJ. Bruce Fields * and source (if it is not a directory). 43221b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 43231da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 43241da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4325a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 43261da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 43271da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 43281da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4329a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 43301da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 43311da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 43321da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4333e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 43341b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 43351da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4336c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 43371da177e4SLinus Torvalds * locking]. 43381da177e4SLinus Torvalds */ 43391da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 43408e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4341520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 43421da177e4SLinus Torvalds { 43431da177e4SLinus Torvalds int error; 4344bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4345bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4346bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4347da1ce067SMiklos Szeredi bool new_is_dir = false; 4348da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 434949d31c2fSAl Viro struct name_snapshot old_name; 43501da177e4SLinus Torvalds 43518d3e2936SMiklos Szeredi if (source == target) 43521da177e4SLinus Torvalds return 0; 43531da177e4SLinus Torvalds 43541da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 43551da177e4SLinus Torvalds if (error) 43561da177e4SLinus Torvalds return error; 43571da177e4SLinus Torvalds 4358da1ce067SMiklos Szeredi if (!target) { 4359a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4360da1ce067SMiklos Szeredi } else { 4361da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4362da1ce067SMiklos Szeredi 4363da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43641da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4365da1ce067SMiklos Szeredi else 4366da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4367da1ce067SMiklos Szeredi } 43681da177e4SLinus Torvalds if (error) 43691da177e4SLinus Torvalds return error; 43701da177e4SLinus Torvalds 43712773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 43721da177e4SLinus Torvalds return -EPERM; 43731da177e4SLinus Torvalds 4374bc27027aSMiklos Szeredi /* 4375bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4376bc27027aSMiklos Szeredi * we'll need to flip '..'. 4377bc27027aSMiklos Szeredi */ 4378da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4379da1ce067SMiklos Szeredi if (is_dir) { 4380bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4381bc27027aSMiklos Szeredi if (error) 4382bc27027aSMiklos Szeredi return error; 4383bc27027aSMiklos Szeredi } 4384da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4385da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4386da1ce067SMiklos Szeredi if (error) 4387da1ce067SMiklos Szeredi return error; 4388da1ce067SMiklos Szeredi } 4389da1ce067SMiklos Szeredi } 43900eeca283SRobert Love 43910b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43920b3974ebSMiklos Szeredi flags); 4393bc27027aSMiklos Szeredi if (error) 4394bc27027aSMiklos Szeredi return error; 4395bc27027aSMiklos Szeredi 439649d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4397bc27027aSMiklos Szeredi dget(new_dentry); 4398da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4399bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4400bc27027aSMiklos Szeredi else if (target) 44015955102cSAl Viro inode_lock(target); 4402bc27027aSMiklos Szeredi 4403bc27027aSMiklos Szeredi error = -EBUSY; 44047af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4405bc27027aSMiklos Szeredi goto out; 4406bc27027aSMiklos Szeredi 4407da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4408bc27027aSMiklos Szeredi error = -EMLINK; 4409da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4410bc27027aSMiklos Szeredi goto out; 4411da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4412da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4413da1ce067SMiklos Szeredi goto out; 4414da1ce067SMiklos Szeredi } 4415da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4416bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4417da1ce067SMiklos Szeredi if (!is_dir) { 4418bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4419bc27027aSMiklos Szeredi if (error) 4420bc27027aSMiklos Szeredi goto out; 4421da1ce067SMiklos Szeredi } 4422da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4423bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4424bc27027aSMiklos Szeredi if (error) 4425bc27027aSMiklos Szeredi goto out; 4426bc27027aSMiklos Szeredi } 4427520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4428520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4429bc27027aSMiklos Szeredi if (error) 4430bc27027aSMiklos Szeredi goto out; 4431bc27027aSMiklos Szeredi 4432da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 44331da177e4SLinus Torvalds if (is_dir) 4434bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4435bc27027aSMiklos Szeredi dont_mount(new_dentry); 44368ed936b5SEric W. Biederman detach_mounts(new_dentry); 4437bc27027aSMiklos Szeredi } 4438da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4439da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4440bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4441da1ce067SMiklos Szeredi else 4442da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4443da1ce067SMiklos Szeredi } 4444bc27027aSMiklos Szeredi out: 4445da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4446bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4447bc27027aSMiklos Szeredi else if (target) 44485955102cSAl Viro inode_unlock(target); 4449bc27027aSMiklos Szeredi dput(new_dentry); 4450da1ce067SMiklos Szeredi if (!error) { 445149d31c2fSAl Viro fsnotify_move(old_dir, new_dir, old_name.name, is_dir, 4452da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4453da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4454da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4455da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4456da1ce067SMiklos Szeredi } 4457da1ce067SMiklos Szeredi } 445849d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 44590eeca283SRobert Love 44601da177e4SLinus Torvalds return error; 44611da177e4SLinus Torvalds } 44624d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 44631da177e4SLinus Torvalds 4464520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4465520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 44661da177e4SLinus Torvalds { 44671da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 44681da177e4SLinus Torvalds struct dentry *trap; 4469f5beed75SAl Viro struct path old_path, new_path; 4470f5beed75SAl Viro struct qstr old_last, new_last; 4471f5beed75SAl Viro int old_type, new_type; 44728e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 447391a27b2aSJeff Layton struct filename *from; 447491a27b2aSJeff Layton struct filename *to; 4475f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4476c6a94284SJeff Layton bool should_retry = false; 44772ad94ae6SAl Viro int error; 4478520c8b16SMiklos Szeredi 44790d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4480da1ce067SMiklos Szeredi return -EINVAL; 4481da1ce067SMiklos Szeredi 44820d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 44830d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4484520c8b16SMiklos Szeredi return -EINVAL; 4485520c8b16SMiklos Szeredi 44860d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 44870d7a8555SMiklos Szeredi return -EPERM; 44880d7a8555SMiklos Szeredi 4489f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4490f5beed75SAl Viro target_flags = 0; 4491f5beed75SAl Viro 4492c6a94284SJeff Layton retry: 4493c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4494c1d4dd27SAl Viro &old_path, &old_last, &old_type); 449591a27b2aSJeff Layton if (IS_ERR(from)) { 449691a27b2aSJeff Layton error = PTR_ERR(from); 44971da177e4SLinus Torvalds goto exit; 449891a27b2aSJeff Layton } 44991da177e4SLinus Torvalds 4500c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4501c1d4dd27SAl Viro &new_path, &new_last, &new_type); 450291a27b2aSJeff Layton if (IS_ERR(to)) { 450391a27b2aSJeff Layton error = PTR_ERR(to); 45041da177e4SLinus Torvalds goto exit1; 450591a27b2aSJeff Layton } 45061da177e4SLinus Torvalds 45071da177e4SLinus Torvalds error = -EXDEV; 4508f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 45091da177e4SLinus Torvalds goto exit2; 45101da177e4SLinus Torvalds 45111da177e4SLinus Torvalds error = -EBUSY; 4512f5beed75SAl Viro if (old_type != LAST_NORM) 45131da177e4SLinus Torvalds goto exit2; 45141da177e4SLinus Torvalds 45150a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 45160a7c3937SMiklos Szeredi error = -EEXIST; 4517f5beed75SAl Viro if (new_type != LAST_NORM) 45181da177e4SLinus Torvalds goto exit2; 45191da177e4SLinus Torvalds 4520f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4521c30dabfeSJan Kara if (error) 4522c30dabfeSJan Kara goto exit2; 4523c30dabfeSJan Kara 45248e6d782cSJ. Bruce Fields retry_deleg: 4525f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 45261da177e4SLinus Torvalds 4527f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 45281da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 45291da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 45301da177e4SLinus Torvalds goto exit3; 45311da177e4SLinus Torvalds /* source must exist */ 45321da177e4SLinus Torvalds error = -ENOENT; 4533b18825a7SDavid Howells if (d_is_negative(old_dentry)) 45341da177e4SLinus Torvalds goto exit4; 4535f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 45361da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 45371da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 45381da177e4SLinus Torvalds goto exit4; 45390a7c3937SMiklos Szeredi error = -EEXIST; 45400a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 45410a7c3937SMiklos Szeredi goto exit5; 4542da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4543da1ce067SMiklos Szeredi error = -ENOENT; 4544da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4545da1ce067SMiklos Szeredi goto exit5; 4546da1ce067SMiklos Szeredi 4547da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4548da1ce067SMiklos Szeredi error = -ENOTDIR; 4549f5beed75SAl Viro if (new_last.name[new_last.len]) 4550da1ce067SMiklos Szeredi goto exit5; 4551da1ce067SMiklos Szeredi } 4552da1ce067SMiklos Szeredi } 45530a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 45540a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 45550a7c3937SMiklos Szeredi error = -ENOTDIR; 4556f5beed75SAl Viro if (old_last.name[old_last.len]) 45570a7c3937SMiklos Szeredi goto exit5; 4558f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 45590a7c3937SMiklos Szeredi goto exit5; 45600a7c3937SMiklos Szeredi } 45610a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 45620a7c3937SMiklos Szeredi error = -EINVAL; 45630a7c3937SMiklos Szeredi if (old_dentry == trap) 45640a7c3937SMiklos Szeredi goto exit5; 45651da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4566da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 45671da177e4SLinus Torvalds error = -ENOTEMPTY; 45681da177e4SLinus Torvalds if (new_dentry == trap) 45691da177e4SLinus Torvalds goto exit5; 45701da177e4SLinus Torvalds 4571f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4572f5beed75SAl Viro &new_path, new_dentry, flags); 4573be6d3e56SKentaro Takeda if (error) 4574c30dabfeSJan Kara goto exit5; 4575f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4576f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4577520c8b16SMiklos Szeredi &delegated_inode, flags); 45781da177e4SLinus Torvalds exit5: 45791da177e4SLinus Torvalds dput(new_dentry); 45801da177e4SLinus Torvalds exit4: 45811da177e4SLinus Torvalds dput(old_dentry); 45821da177e4SLinus Torvalds exit3: 4583f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 45848e6d782cSJ. Bruce Fields if (delegated_inode) { 45858e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 45868e6d782cSJ. Bruce Fields if (!error) 45878e6d782cSJ. Bruce Fields goto retry_deleg; 45888e6d782cSJ. Bruce Fields } 4589f5beed75SAl Viro mnt_drop_write(old_path.mnt); 45901da177e4SLinus Torvalds exit2: 4591c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4592c6a94284SJeff Layton should_retry = true; 4593f5beed75SAl Viro path_put(&new_path); 45942ad94ae6SAl Viro putname(to); 45951da177e4SLinus Torvalds exit1: 4596f5beed75SAl Viro path_put(&old_path); 45971da177e4SLinus Torvalds putname(from); 4598c6a94284SJeff Layton if (should_retry) { 4599c6a94284SJeff Layton should_retry = false; 4600c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4601c6a94284SJeff Layton goto retry; 4602c6a94284SJeff Layton } 46032ad94ae6SAl Viro exit: 46041da177e4SLinus Torvalds return error; 46051da177e4SLinus Torvalds } 46061da177e4SLinus Torvalds 4607520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4608520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4609520c8b16SMiklos Szeredi { 4610520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4611520c8b16SMiklos Szeredi } 4612520c8b16SMiklos Szeredi 4613a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 46145590ff0dSUlrich Drepper { 4615520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 46165590ff0dSUlrich Drepper } 46175590ff0dSUlrich Drepper 4618787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4619787fb6bcSMiklos Szeredi { 4620787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4621787fb6bcSMiklos Szeredi if (error) 4622787fb6bcSMiklos Szeredi return error; 4623787fb6bcSMiklos Szeredi 4624787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4625787fb6bcSMiklos Szeredi return -EPERM; 4626787fb6bcSMiklos Szeredi 4627787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4628787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4629787fb6bcSMiklos Szeredi } 4630787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4631787fb6bcSMiklos Szeredi 46325d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 46331da177e4SLinus Torvalds { 46345d826c84SAl Viro int len = PTR_ERR(link); 46351da177e4SLinus Torvalds if (IS_ERR(link)) 46361da177e4SLinus Torvalds goto out; 46371da177e4SLinus Torvalds 46381da177e4SLinus Torvalds len = strlen(link); 46391da177e4SLinus Torvalds if (len > (unsigned) buflen) 46401da177e4SLinus Torvalds len = buflen; 46411da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 46421da177e4SLinus Torvalds len = -EFAULT; 46431da177e4SLinus Torvalds out: 46441da177e4SLinus Torvalds return len; 46451da177e4SLinus Torvalds } 46461da177e4SLinus Torvalds 46471da177e4SLinus Torvalds /* 46481da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 46496b255391SAl Viro * have ->get_link() not calling nd_jump_link(). Using (or not using) it 46506b255391SAl Viro * for any given inode is up to filesystem. 46511da177e4SLinus Torvalds */ 4652d16744ecSMiklos Szeredi static int generic_readlink(struct dentry *dentry, char __user *buffer, 4653d16744ecSMiklos Szeredi int buflen) 46541da177e4SLinus Torvalds { 4655fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46565f2c4179SAl Viro struct inode *inode = d_inode(dentry); 46575f2c4179SAl Viro const char *link = inode->i_link; 4658694a1764SMarcin Slusarz int res; 4659cc314eefSLinus Torvalds 4660d4dee48bSAl Viro if (!link) { 4661fceef393SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4662680baacbSAl Viro if (IS_ERR(link)) 4663680baacbSAl Viro return PTR_ERR(link); 4664d4dee48bSAl Viro } 4665680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4666fceef393SAl Viro do_delayed_call(&done); 4667694a1764SMarcin Slusarz return res; 46681da177e4SLinus Torvalds } 46691da177e4SLinus Torvalds 4670d60874cdSMiklos Szeredi /** 4671fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4672fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4673fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4674fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4675fd4a0edfSMiklos Szeredi * 4676fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4677fd4a0edfSMiklos Szeredi * 4678fd4a0edfSMiklos Szeredi * Does not call security hook. 4679fd4a0edfSMiklos Szeredi */ 4680fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4681fd4a0edfSMiklos Szeredi { 4682fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4683fd4a0edfSMiklos Szeredi 468476fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 468576fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 468676fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 468776fca90eSMiklos Szeredi 468876fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4689fd4a0edfSMiklos Szeredi return -EINVAL; 4690fd4a0edfSMiklos Szeredi 469176fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 469276fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 469376fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 469476fca90eSMiklos Szeredi } 469576fca90eSMiklos Szeredi 469676fca90eSMiklos Szeredi return generic_readlink(dentry, buffer, buflen); 4697fd4a0edfSMiklos Szeredi } 4698fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46991da177e4SLinus Torvalds 4700d60874cdSMiklos Szeredi /** 4701d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4702d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4703d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4704d60874cdSMiklos Szeredi * 4705d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4706d60874cdSMiklos Szeredi * 4707d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4708d60874cdSMiklos Szeredi * 4709d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4710d60874cdSMiklos Szeredi */ 4711d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4712d60874cdSMiklos Szeredi { 4713d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4714d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4715d60874cdSMiklos Szeredi 4716d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4717d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4718d60874cdSMiklos Szeredi if (!res) 4719d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4720d60874cdSMiklos Szeredi } 4721d60874cdSMiklos Szeredi return res; 4722d60874cdSMiklos Szeredi } 4723d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4724d60874cdSMiklos Szeredi 47251da177e4SLinus Torvalds /* get the link contents into pagecache */ 47266b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4727fceef393SAl Viro struct delayed_call *callback) 47281da177e4SLinus Torvalds { 4729ebd09abbSDuane Griffin char *kaddr; 47301da177e4SLinus Torvalds struct page *page; 47316b255391SAl Viro struct address_space *mapping = inode->i_mapping; 47326b255391SAl Viro 4733d3883d4fSAl Viro if (!dentry) { 4734d3883d4fSAl Viro page = find_get_page(mapping, 0); 4735d3883d4fSAl Viro if (!page) 47366b255391SAl Viro return ERR_PTR(-ECHILD); 4737d3883d4fSAl Viro if (!PageUptodate(page)) { 4738d3883d4fSAl Viro put_page(page); 4739d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4740d3883d4fSAl Viro } 4741d3883d4fSAl Viro } else { 4742090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 47431da177e4SLinus Torvalds if (IS_ERR(page)) 47446fe6900eSNick Piggin return (char*)page; 4745d3883d4fSAl Viro } 4746fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 474721fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 474821fc61c7SAl Viro kaddr = page_address(page); 47496b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4750ebd09abbSDuane Griffin return kaddr; 47511da177e4SLinus Torvalds } 47521da177e4SLinus Torvalds 47536b255391SAl Viro EXPORT_SYMBOL(page_get_link); 47541da177e4SLinus Torvalds 4755fceef393SAl Viro void page_put_link(void *arg) 47561da177e4SLinus Torvalds { 4757fceef393SAl Viro put_page(arg); 47581da177e4SLinus Torvalds } 47594d359507SAl Viro EXPORT_SYMBOL(page_put_link); 47601da177e4SLinus Torvalds 4761aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4762aa80deabSAl Viro { 4763fceef393SAl Viro DEFINE_DELAYED_CALL(done); 47646b255391SAl Viro int res = readlink_copy(buffer, buflen, 47656b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4766fceef393SAl Viro &done)); 4767fceef393SAl Viro do_delayed_call(&done); 4768aa80deabSAl Viro return res; 4769aa80deabSAl Viro } 4770aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4771aa80deabSAl Viro 477254566b2cSNick Piggin /* 477354566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 477454566b2cSNick Piggin */ 477554566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 47761da177e4SLinus Torvalds { 47771da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 47780adb25d2SKirill Korotaev struct page *page; 4779afddba49SNick Piggin void *fsdata; 4780beb497abSDmitriy Monakhov int err; 4781c718a975STetsuo Handa unsigned int flags = 0; 478254566b2cSNick Piggin if (nofs) 478354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 47841da177e4SLinus Torvalds 47857e53cac4SNeilBrown retry: 4786afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 478754566b2cSNick Piggin flags, &page, &fsdata); 47881da177e4SLinus Torvalds if (err) 4789afddba49SNick Piggin goto fail; 4790afddba49SNick Piggin 479121fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4792afddba49SNick Piggin 4793afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4794afddba49SNick Piggin page, fsdata); 47951da177e4SLinus Torvalds if (err < 0) 47961da177e4SLinus Torvalds goto fail; 4797afddba49SNick Piggin if (err < len-1) 4798afddba49SNick Piggin goto retry; 4799afddba49SNick Piggin 48001da177e4SLinus Torvalds mark_inode_dirty(inode); 48011da177e4SLinus Torvalds return 0; 48021da177e4SLinus Torvalds fail: 48031da177e4SLinus Torvalds return err; 48041da177e4SLinus Torvalds } 48054d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 48061da177e4SLinus Torvalds 48070adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 48080adb25d2SKirill Korotaev { 48090adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4810c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 48110adb25d2SKirill Korotaev } 48124d359507SAl Viro EXPORT_SYMBOL(page_symlink); 48130adb25d2SKirill Korotaev 481492e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 48156b255391SAl Viro .get_link = page_get_link, 48161da177e4SLinus Torvalds }; 48171da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4818