1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 494ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 5069883d185SAl Viro unsigned root_seq; 5079883d185SAl Viro int dfd; 5083859a271SKees Cook } __randomize_layout; 5091f55a6ecSAl Viro 5109883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 511894bc8c4SAl Viro { 512756daf26SNeilBrown struct nameidata *old = current->nameidata; 513756daf26SNeilBrown p->stack = p->internal; 514c8a53ee5SAl Viro p->dfd = dfd; 515c8a53ee5SAl Viro p->name = name; 516756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5179883d185SAl Viro p->saved = old; 518756daf26SNeilBrown current->nameidata = p; 519894bc8c4SAl Viro } 520894bc8c4SAl Viro 5219883d185SAl Viro static void restore_nameidata(void) 522894bc8c4SAl Viro { 5239883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 524756daf26SNeilBrown 525756daf26SNeilBrown current->nameidata = old; 526756daf26SNeilBrown if (old) 527756daf26SNeilBrown old->total_link_count = now->total_link_count; 528e1a63bbcSAl Viro if (now->stack != now->internal) 529756daf26SNeilBrown kfree(now->stack); 530894bc8c4SAl Viro } 531894bc8c4SAl Viro 532894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 533894bc8c4SAl Viro { 534bc40aee0SAl Viro struct saved *p; 535bc40aee0SAl Viro 536bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5376da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 538bc40aee0SAl Viro GFP_ATOMIC); 539bc40aee0SAl Viro if (unlikely(!p)) 540bc40aee0SAl Viro return -ECHILD; 541bc40aee0SAl Viro } else { 5426da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 543894bc8c4SAl Viro GFP_KERNEL); 544894bc8c4SAl Viro if (unlikely(!p)) 545894bc8c4SAl Viro return -ENOMEM; 546bc40aee0SAl Viro } 547894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 548894bc8c4SAl Viro nd->stack = p; 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro } 551894bc8c4SAl Viro 552397d425dSEric W. Biederman /** 5536b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 554397d425dSEric W. Biederman * 555397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 556397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 557397d425dSEric W. Biederman */ 5586b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 559397d425dSEric W. Biederman { 56095dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 561397d425dSEric W. Biederman 56295dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56395dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 564397d425dSEric W. Biederman return true; 565397d425dSEric W. Biederman 5666b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 567397d425dSEric W. Biederman } 568397d425dSEric W. Biederman 569894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 570894bc8c4SAl Viro { 571da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 572894bc8c4SAl Viro return 0; 573894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 574894bc8c4SAl Viro return 0; 575894bc8c4SAl Viro return __nd_alloc_stack(nd); 576894bc8c4SAl Viro } 577894bc8c4SAl Viro 5787973387aSAl Viro static void drop_links(struct nameidata *nd) 5797973387aSAl Viro { 5807973387aSAl Viro int i = nd->depth; 5817973387aSAl Viro while (i--) { 5827973387aSAl Viro struct saved *last = nd->stack + i; 583fceef393SAl Viro do_delayed_call(&last->done); 584fceef393SAl Viro clear_delayed_call(&last->done); 5857973387aSAl Viro } 5867973387aSAl Viro } 5877973387aSAl Viro 5887973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5897973387aSAl Viro { 5907973387aSAl Viro drop_links(nd); 5917973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5927973387aSAl Viro int i; 5937973387aSAl Viro path_put(&nd->path); 5947973387aSAl Viro for (i = 0; i < nd->depth; i++) 5957973387aSAl Viro path_put(&nd->stack[i].link); 59684a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 597102b8af2SAl Viro path_put(&nd->root); 59884a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 599102b8af2SAl Viro } 6007973387aSAl Viro } else { 6017973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6027973387aSAl Viro rcu_read_unlock(); 6037973387aSAl Viro } 6047973387aSAl Viro nd->depth = 0; 6057973387aSAl Viro } 6067973387aSAl Viro 6077973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6087973387aSAl Viro static bool legitimize_path(struct nameidata *nd, 6097973387aSAl Viro struct path *path, unsigned seq) 6107973387aSAl Viro { 6117973387aSAl Viro int res = __legitimize_mnt(path->mnt, nd->m_seq); 6127973387aSAl Viro if (unlikely(res)) { 6137973387aSAl Viro if (res > 0) 6147973387aSAl Viro path->mnt = NULL; 6157973387aSAl Viro path->dentry = NULL; 6167973387aSAl Viro return false; 6177973387aSAl Viro } 6187973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6197973387aSAl Viro path->dentry = NULL; 6207973387aSAl Viro return false; 6217973387aSAl Viro } 6227973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6237973387aSAl Viro } 6247973387aSAl Viro 6257973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6267973387aSAl Viro { 6277973387aSAl Viro int i; 6287973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6297973387aSAl Viro struct saved *last = nd->stack + i; 6307973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6317973387aSAl Viro drop_links(nd); 6327973387aSAl Viro nd->depth = i + 1; 6337973387aSAl Viro return false; 6347973387aSAl Viro } 6357973387aSAl Viro } 6367973387aSAl Viro return true; 6377973387aSAl Viro } 6387973387aSAl Viro 639ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 640ee594bffSAl Viro { 641adb21d2bSAleksa Sarai /* 642adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 643adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 644adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 645adb21d2bSAleksa Sarai */ 646adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 647adb21d2bSAleksa Sarai return false; 648adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 649ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 650ee594bffSAl Viro return true; 65184a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 652ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 653ee594bffSAl Viro } 654ee594bffSAl Viro 65519660af7SAl Viro /* 65631e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 65719660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 65819660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 65957e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66019660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66119660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66219660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66319660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66431e6b01fSNick Piggin */ 66531e6b01fSNick Piggin 66631e6b01fSNick Piggin /** 66719660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 66819660af7SAl Viro * @nd: nameidata pathwalk data 66939191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67031e6b01fSNick Piggin * 6714675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6724675ac39SAl Viro * for ref-walk mode. 6734675ac39SAl Viro * Must be called from rcu-walk context. 6747973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6757973387aSAl Viro * terminate_walk(). 67631e6b01fSNick Piggin */ 6774675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 67831e6b01fSNick Piggin { 67931e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68031e6b01fSNick Piggin 68131e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 682e5c832d5SLinus Torvalds 683e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6847973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6854675ac39SAl Viro goto out1; 68684a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 68784a2bd39SAl Viro goto out; 688ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6894675ac39SAl Viro goto out; 6904675ac39SAl Viro rcu_read_unlock(); 6914675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6924675ac39SAl Viro return 0; 6934675ac39SAl Viro 69484a2bd39SAl Viro out1: 6954675ac39SAl Viro nd->path.mnt = NULL; 6964675ac39SAl Viro nd->path.dentry = NULL; 6974675ac39SAl Viro out: 6984675ac39SAl Viro rcu_read_unlock(); 6994675ac39SAl Viro return -ECHILD; 7004675ac39SAl Viro } 7014675ac39SAl Viro 7024675ac39SAl Viro /** 7034675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7044675ac39SAl Viro * @nd: nameidata pathwalk data 7054675ac39SAl Viro * @dentry: child of nd->path.dentry 7064675ac39SAl Viro * @seq: seq number to check dentry against 7074675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7084675ac39SAl Viro * 7094675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7104675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7114675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7124675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7134675ac39SAl Viro * terminate_walk(). 7144675ac39SAl Viro */ 7154675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7164675ac39SAl Viro { 7174675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7184675ac39SAl Viro 7194675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7204675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7214675ac39SAl Viro goto out2; 7227973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7237973387aSAl Viro goto out2; 7244675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7257973387aSAl Viro goto out1; 72648a066e7SAl Viro 72715570086SLinus Torvalds /* 7284675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7294675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7304675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7314675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7324675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73315570086SLinus Torvalds */ 7344675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 735e5c832d5SLinus Torvalds goto out; 73684a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 73784a2bd39SAl Viro goto out_dput; 738e5c832d5SLinus Torvalds /* 739e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 740e5c832d5SLinus Torvalds * still valid and get it if required. 741e5c832d5SLinus Torvalds */ 74284a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74384a2bd39SAl Viro goto out_dput; 7448b61e74fSAl Viro rcu_read_unlock(); 74531e6b01fSNick Piggin return 0; 74619660af7SAl Viro 7477973387aSAl Viro out2: 7487973387aSAl Viro nd->path.mnt = NULL; 7497973387aSAl Viro out1: 7507973387aSAl Viro nd->path.dentry = NULL; 751e5c832d5SLinus Torvalds out: 7528b61e74fSAl Viro rcu_read_unlock(); 75384a2bd39SAl Viro return -ECHILD; 75484a2bd39SAl Viro out_dput: 75584a2bd39SAl Viro rcu_read_unlock(); 75684a2bd39SAl Viro dput(dentry); 75731e6b01fSNick Piggin return -ECHILD; 75831e6b01fSNick Piggin } 75931e6b01fSNick Piggin 7604ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76134286d66SNick Piggin { 762a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7634ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 764a89f8337SAl Viro else 765a89f8337SAl Viro return 1; 76634286d66SNick Piggin } 76734286d66SNick Piggin 7689f1fafeeSAl Viro /** 7699f1fafeeSAl Viro * complete_walk - successful completion of path walk 7709f1fafeeSAl Viro * @nd: pointer nameidata 77139159de2SJeff Layton * 7729f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7739f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7749f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7759f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7769f1fafeeSAl Viro * need to drop nd->path. 77739159de2SJeff Layton */ 7789f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 77939159de2SJeff Layton { 78016c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78139159de2SJeff Layton int status; 78239159de2SJeff Layton 7839f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 784adb21d2bSAleksa Sarai /* 785adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 786adb21d2bSAleksa Sarai * externally-managed nd->root. 787adb21d2bSAleksa Sarai */ 788adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7899f1fafeeSAl Viro nd->root.mnt = NULL; 7904675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79148a066e7SAl Viro return -ECHILD; 79248a066e7SAl Viro } 7939f1fafeeSAl Viro 794adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 795adb21d2bSAleksa Sarai /* 796adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 797adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 798adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 799adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 800adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 801adb21d2bSAleksa Sarai * 802adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 803adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 804adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 805adb21d2bSAleksa Sarai * requested root to userspace. 806adb21d2bSAleksa Sarai * 807adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 808adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 809adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 810adb21d2bSAleksa Sarai */ 811adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 812adb21d2bSAleksa Sarai return -EXDEV; 813adb21d2bSAleksa Sarai } 814adb21d2bSAleksa Sarai 81516c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 81639159de2SJeff Layton return 0; 81739159de2SJeff Layton 818ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 81916c2cd71SAl Viro return 0; 82016c2cd71SAl Viro 821ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82239159de2SJeff Layton if (status > 0) 82339159de2SJeff Layton return 0; 82439159de2SJeff Layton 82516c2cd71SAl Viro if (!status) 82639159de2SJeff Layton status = -ESTALE; 82716c2cd71SAl Viro 82839159de2SJeff Layton return status; 82939159de2SJeff Layton } 83039159de2SJeff Layton 831740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8322a737871SAl Viro { 83331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8349e6697e2SAl Viro 835adb21d2bSAleksa Sarai /* 836adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 837adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 838adb21d2bSAleksa Sarai * from the dirfd. 839adb21d2bSAleksa Sarai */ 840adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 841adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 842adb21d2bSAleksa Sarai 8439e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8448f47a016SAl Viro unsigned seq; 845c28cc364SNick Piggin 846c28cc364SNick Piggin do { 847c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 84831e6b01fSNick Piggin nd->root = fs->root; 8498f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 850c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8519e6697e2SAl Viro } else { 8529e6697e2SAl Viro get_fs_root(fs, &nd->root); 85384a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8549e6697e2SAl Viro } 855740a1678SAleksa Sarai return 0; 85631e6b01fSNick Piggin } 85731e6b01fSNick Piggin 8587b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 8597b9337aaSNick Piggin struct nameidata *nd) 860051d3812SIan Kent { 86131e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 8624ac91378SJan Blunck dput(nd->path.dentry); 86331e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 8644ac91378SJan Blunck mntput(nd->path.mnt); 8659a229683SHuang Shijie } 86631e6b01fSNick Piggin nd->path.mnt = path->mnt; 8674ac91378SJan Blunck nd->path.dentry = path->dentry; 868051d3812SIan Kent } 869051d3812SIan Kent 870248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 871248fb5b9SAl Viro { 872adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 873adb21d2bSAleksa Sarai return -EXDEV; 87472ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 87572ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 87672ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 87772ba2929SAleksa Sarai return -EXDEV; 87872ba2929SAleksa Sarai } 879740a1678SAleksa Sarai if (!nd->root.mnt) { 880740a1678SAleksa Sarai int error = set_root(nd); 881740a1678SAleksa Sarai if (error) 882740a1678SAleksa Sarai return error; 883740a1678SAleksa Sarai } 884248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 885248fb5b9SAl Viro struct dentry *d; 886248fb5b9SAl Viro nd->path = nd->root; 887248fb5b9SAl Viro d = nd->path.dentry; 888248fb5b9SAl Viro nd->inode = d->d_inode; 889248fb5b9SAl Viro nd->seq = nd->root_seq; 890248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 891248fb5b9SAl Viro return -ECHILD; 892248fb5b9SAl Viro } else { 893248fb5b9SAl Viro path_put(&nd->path); 894248fb5b9SAl Viro nd->path = nd->root; 895248fb5b9SAl Viro path_get(&nd->path); 896248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 897248fb5b9SAl Viro } 898248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 899248fb5b9SAl Viro return 0; 900248fb5b9SAl Viro } 901248fb5b9SAl Viro 902b5fb63c1SChristoph Hellwig /* 9036b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 904b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 905b5fb63c1SChristoph Hellwig */ 9061bc82070SAleksa Sarai int nd_jump_link(struct path *path) 907b5fb63c1SChristoph Hellwig { 9084b99d499SAleksa Sarai int error = -ELOOP; 9096e77137bSAl Viro struct nameidata *nd = current->nameidata; 910b5fb63c1SChristoph Hellwig 9114b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9124b99d499SAleksa Sarai goto err; 9134b99d499SAleksa Sarai 91472ba2929SAleksa Sarai error = -EXDEV; 91572ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 91672ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 91772ba2929SAleksa Sarai goto err; 91872ba2929SAleksa Sarai } 919adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 920adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 921adb21d2bSAleksa Sarai goto err; 92272ba2929SAleksa Sarai 9234b99d499SAleksa Sarai path_put(&nd->path); 924b5fb63c1SChristoph Hellwig nd->path = *path; 925b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 926b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9271bc82070SAleksa Sarai return 0; 9284b99d499SAleksa Sarai 9294b99d499SAleksa Sarai err: 9304b99d499SAleksa Sarai path_put(path); 9314b99d499SAleksa Sarai return error; 932b5fb63c1SChristoph Hellwig } 933b5fb63c1SChristoph Hellwig 934b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 935574197e0SAl Viro { 93621c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 937fceef393SAl Viro do_delayed_call(&last->done); 9386548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 939b9ff4429SAl Viro path_put(&last->link); 940574197e0SAl Viro } 941574197e0SAl Viro 942561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 943561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 94430aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 94530aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 946800179c9SKees Cook 947800179c9SKees Cook /** 948800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 94955852635SRandy Dunlap * @nd: nameidata pathwalk data 950800179c9SKees Cook * 951800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 952800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 953800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 954800179c9SKees Cook * processes from failing races against path names that may change out 955800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 956800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 957800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 958800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 959800179c9SKees Cook * 960800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 961800179c9SKees Cook */ 962ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 963800179c9SKees Cook { 964800179c9SKees Cook const struct inode *parent; 9652d7f9e2aSSeth Forshee kuid_t puid; 966800179c9SKees Cook 967800179c9SKees Cook if (!sysctl_protected_symlinks) 968800179c9SKees Cook return 0; 969800179c9SKees Cook 970800179c9SKees Cook /* Allowed if owner and follower match. */ 97181abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 972800179c9SKees Cook return 0; 973800179c9SKees Cook 974800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 975aa65fa35SAl Viro parent = nd->inode; 976800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 977800179c9SKees Cook return 0; 978800179c9SKees Cook 979800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9802d7f9e2aSSeth Forshee puid = parent->i_uid; 9812d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 982800179c9SKees Cook return 0; 983800179c9SKees Cook 98431956502SAl Viro if (nd->flags & LOOKUP_RCU) 98531956502SAl Viro return -ECHILD; 98631956502SAl Viro 987ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 988245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 989800179c9SKees Cook return -EACCES; 990800179c9SKees Cook } 991800179c9SKees Cook 992800179c9SKees Cook /** 993800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 994800179c9SKees Cook * @inode: the source inode to hardlink from 995800179c9SKees Cook * 996800179c9SKees Cook * Return false if at least one of the following conditions: 997800179c9SKees Cook * - inode is not a regular file 998800179c9SKees Cook * - inode is setuid 999800179c9SKees Cook * - inode is setgid and group-exec 1000800179c9SKees Cook * - access failure for read and write 1001800179c9SKees Cook * 1002800179c9SKees Cook * Otherwise returns true. 1003800179c9SKees Cook */ 1004800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 1005800179c9SKees Cook { 1006800179c9SKees Cook umode_t mode = inode->i_mode; 1007800179c9SKees Cook 1008800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1009800179c9SKees Cook if (!S_ISREG(mode)) 1010800179c9SKees Cook return false; 1011800179c9SKees Cook 1012800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1013800179c9SKees Cook if (mode & S_ISUID) 1014800179c9SKees Cook return false; 1015800179c9SKees Cook 1016800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1017800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1018800179c9SKees Cook return false; 1019800179c9SKees Cook 1020800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1021800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1022800179c9SKees Cook return false; 1023800179c9SKees Cook 1024800179c9SKees Cook return true; 1025800179c9SKees Cook } 1026800179c9SKees Cook 1027800179c9SKees Cook /** 1028800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1029800179c9SKees Cook * @link: the source to hardlink from 1030800179c9SKees Cook * 1031800179c9SKees Cook * Block hardlink when all of: 1032800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1033800179c9SKees Cook * - fsuid does not match inode 1034800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1035f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1036800179c9SKees Cook * 1037800179c9SKees Cook * Returns 0 if successful, -ve on error. 1038800179c9SKees Cook */ 1039800179c9SKees Cook static int may_linkat(struct path *link) 1040800179c9SKees Cook { 1041593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1042593d1ce8SEric W. Biederman 1043593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1044593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1045593d1ce8SEric W. Biederman return -EOVERFLOW; 1046800179c9SKees Cook 1047800179c9SKees Cook if (!sysctl_protected_hardlinks) 1048800179c9SKees Cook return 0; 1049800179c9SKees Cook 1050800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1051800179c9SKees Cook * otherwise, it must be a safe source. 1052800179c9SKees Cook */ 1053cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1054800179c9SKees Cook return 0; 1055800179c9SKees Cook 1056245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1057800179c9SKees Cook return -EPERM; 1058800179c9SKees Cook } 1059800179c9SKees Cook 106030aba665SSalvatore Mesoraca /** 106130aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 106230aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 106330aba665SSalvatore Mesoraca * exist. 1064d0cb5018SAl Viro * @dir_mode: mode bits of directory 1065d0cb5018SAl Viro * @dir_uid: owner of directory 106630aba665SSalvatore Mesoraca * @inode: the inode of the file to open 106730aba665SSalvatore Mesoraca * 106830aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 106930aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 107030aba665SSalvatore Mesoraca * - the file already exists 107130aba665SSalvatore Mesoraca * - we are in a sticky directory 107230aba665SSalvatore Mesoraca * - we don't own the file 107330aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 107430aba665SSalvatore Mesoraca * - the directory is world writable 107530aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 107630aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 107730aba665SSalvatore Mesoraca * be enough. 107830aba665SSalvatore Mesoraca * 107930aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 108030aba665SSalvatore Mesoraca */ 1081d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 108230aba665SSalvatore Mesoraca struct inode * const inode) 108330aba665SSalvatore Mesoraca { 108430aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 108530aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1086d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1087d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 108830aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 108930aba665SSalvatore Mesoraca return 0; 109030aba665SSalvatore Mesoraca 1091d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1092d0cb5018SAl Viro (dir_mode & 0020 && 109330aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 109430aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1095245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1096245d7369SKees Cook "sticky_create_fifo" : 1097245d7369SKees Cook "sticky_create_regular"; 1098245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 109930aba665SSalvatore Mesoraca return -EACCES; 110030aba665SSalvatore Mesoraca } 110130aba665SSalvatore Mesoraca return 0; 110230aba665SSalvatore Mesoraca } 110330aba665SSalvatore Mesoraca 1104f015f126SDavid Howells /* 1105f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1106f015f126SDavid Howells * 1107f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1108f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1109f015f126SDavid Howells * Up is towards /. 1110f015f126SDavid Howells * 1111f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1112f015f126SDavid Howells * root. 1113f015f126SDavid Howells */ 1114bab77ebfSAl Viro int follow_up(struct path *path) 11151da177e4SLinus Torvalds { 11160714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11170714a533SAl Viro struct mount *parent; 11181da177e4SLinus Torvalds struct dentry *mountpoint; 111999b7db7bSNick Piggin 112048a066e7SAl Viro read_seqlock_excl(&mount_lock); 11210714a533SAl Viro parent = mnt->mnt_parent; 11223c0a6163SAl Viro if (parent == mnt) { 112348a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11241da177e4SLinus Torvalds return 0; 11251da177e4SLinus Torvalds } 11260714a533SAl Viro mntget(&parent->mnt); 1127a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 112848a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1129bab77ebfSAl Viro dput(path->dentry); 1130bab77ebfSAl Viro path->dentry = mountpoint; 1131bab77ebfSAl Viro mntput(path->mnt); 11320714a533SAl Viro path->mnt = &parent->mnt; 11331da177e4SLinus Torvalds return 1; 11341da177e4SLinus Torvalds } 11354d359507SAl Viro EXPORT_SYMBOL(follow_up); 11361da177e4SLinus Torvalds 1137b5c84bf6SNick Piggin /* 11389875cf80SDavid Howells * Perform an automount 11399875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11409875cf80SDavid Howells * were called with. 11411da177e4SLinus Torvalds */ 11421c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 114331e6b01fSNick Piggin { 114425e195aaSAl Viro struct dentry *dentry = path->dentry; 11459875cf80SDavid Howells 11460ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11470ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11480ec26fd0SMiklos Szeredi * the name. 11490ec26fd0SMiklos Szeredi * 11500ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11515a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11520ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11530ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11540ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11550ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11565a30d8a2SDavid Howells */ 11571c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11585d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 115925e195aaSAl Viro dentry->d_inode) 11609875cf80SDavid Howells return -EISDIR; 11610ec26fd0SMiklos Szeredi 11621c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 11639875cf80SDavid Howells return -ELOOP; 11649875cf80SDavid Howells 116525e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1166ea5b778aSDavid Howells } 11679875cf80SDavid Howells 11689875cf80SDavid Howells /* 11699deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 11709deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 11719deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 11729deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 11739875cf80SDavid Howells */ 11749deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 11759deed3ebSAl Viro int *count, unsigned lookup_flags) 11769875cf80SDavid Howells { 11779deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 11789875cf80SDavid Howells bool need_mntput = false; 11798aef1884SAl Viro int ret = 0; 11809875cf80SDavid Howells 11819deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1182cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1183cc53ce53SDavid Howells * being held. */ 1184d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1185fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1186508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1187cc53ce53SDavid Howells if (ret < 0) 11888aef1884SAl Viro break; 1189cc53ce53SDavid Howells } 1190cc53ce53SDavid Howells 11919deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 11929875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 11939deed3ebSAl Viro if (mounted) { // ... in our namespace 11949875cf80SDavid Howells dput(path->dentry); 11959875cf80SDavid Howells if (need_mntput) 1196463ffb2eSAl Viro mntput(path->mnt); 1197463ffb2eSAl Viro path->mnt = mounted; 1198463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 11999deed3ebSAl Viro // here we know it's positive 12009deed3ebSAl Viro flags = path->dentry->d_flags; 12019875cf80SDavid Howells need_mntput = true; 12029875cf80SDavid Howells continue; 1203463ffb2eSAl Viro } 12041da177e4SLinus Torvalds } 12059875cf80SDavid Howells 12069deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 12079deed3ebSAl Viro break; 12089deed3ebSAl Viro 12099deed3ebSAl Viro // uncovered automount point 12109deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 12119deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 12129875cf80SDavid Howells if (ret < 0) 12138aef1884SAl Viro break; 12149875cf80SDavid Howells } 12159875cf80SDavid Howells 12169deed3ebSAl Viro if (ret == -EISDIR) 12179deed3ebSAl Viro ret = 0; 12189deed3ebSAl Viro // possible if you race with several mount --move 12199deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 12208aef1884SAl Viro mntput(path->mnt); 12219deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1222d41efb52SAl Viro ret = -ENOENT; 12239deed3ebSAl Viro *jumped = need_mntput; 12248402752eSAl Viro return ret; 12251da177e4SLinus Torvalds } 12261da177e4SLinus Torvalds 12279deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 12289deed3ebSAl Viro int *count, unsigned lookup_flags) 12299deed3ebSAl Viro { 12309deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 12319deed3ebSAl Viro 12329deed3ebSAl Viro /* fastpath */ 12339deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 12349deed3ebSAl Viro *jumped = false; 12359deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 12369deed3ebSAl Viro return -ENOENT; 12379deed3ebSAl Viro return 0; 12389deed3ebSAl Viro } 12399deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 12409deed3ebSAl Viro } 12419deed3ebSAl Viro 1242cc53ce53SDavid Howells int follow_down_one(struct path *path) 12431da177e4SLinus Torvalds { 12441da177e4SLinus Torvalds struct vfsmount *mounted; 12451da177e4SLinus Torvalds 12461c755af4SAl Viro mounted = lookup_mnt(path); 12471da177e4SLinus Torvalds if (mounted) { 12489393bd07SAl Viro dput(path->dentry); 12499393bd07SAl Viro mntput(path->mnt); 12509393bd07SAl Viro path->mnt = mounted; 12519393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12521da177e4SLinus Torvalds return 1; 12531da177e4SLinus Torvalds } 12541da177e4SLinus Torvalds return 0; 12551da177e4SLinus Torvalds } 12564d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12571da177e4SLinus Torvalds 12589875cf80SDavid Howells /* 12599deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 12609deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 12619deed3ebSAl Viro * caller is permitted to proceed or not. 12629deed3ebSAl Viro */ 12639deed3ebSAl Viro int follow_down(struct path *path) 12649deed3ebSAl Viro { 12659deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 12669deed3ebSAl Viro bool jumped; 12679deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 12689deed3ebSAl Viro 12699deed3ebSAl Viro if (path->mnt != mnt) 12709deed3ebSAl Viro mntput(mnt); 12719deed3ebSAl Viro return ret; 12729deed3ebSAl Viro } 12739deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 12749deed3ebSAl Viro 12759deed3ebSAl Viro /* 1276287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1277287548e4SAl Viro * we meet a managed dentry that would need blocking. 12789875cf80SDavid Howells */ 12799875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1280254cf582SAl Viro struct inode **inode, unsigned *seqp) 12819875cf80SDavid Howells { 1282ea936aebSAl Viro struct dentry *dentry = path->dentry; 1283ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1284ea936aebSAl Viro 1285ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1286ea936aebSAl Viro return true; 1287ea936aebSAl Viro 1288ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1289ea936aebSAl Viro return false; 1290ea936aebSAl Viro 129162a7375eSIan Kent for (;;) { 129262a7375eSIan Kent /* 129362a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 129462a7375eSIan Kent * that wants to block transit. 129562a7375eSIan Kent */ 1296ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1297ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1298ea936aebSAl Viro if (res) 1299ea936aebSAl Viro return res == -EISDIR; 1300ea936aebSAl Viro flags = dentry->d_flags; 1301b8faf035SNeilBrown } 130262a7375eSIan Kent 1303ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1304ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1305ea936aebSAl Viro if (mounted) { 1306c7105365SAl Viro path->mnt = &mounted->mnt; 1307ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1308a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1309ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1310ea936aebSAl Viro *inode = dentry->d_inode; 131159430262SLinus Torvalds /* 1312ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1313ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1314ea936aebSAl Viro * between mount hash removal and ->mnt_root 1315ea936aebSAl Viro * becoming unpinned. 131659430262SLinus Torvalds */ 1317ea936aebSAl Viro flags = dentry->d_flags; 1318ea936aebSAl Viro continue; 13199875cf80SDavid Howells } 1320ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1321ea936aebSAl Viro return false; 1322ea936aebSAl Viro } 1323ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1324ea936aebSAl Viro } 1325287548e4SAl Viro } 1326287548e4SAl Viro 1327db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1328db3c9adeSAl Viro struct path *path, struct inode **inode, 1329db3c9adeSAl Viro unsigned int *seqp) 1330bd7c4b50SAl Viro { 13319deed3ebSAl Viro bool jumped; 1332db3c9adeSAl Viro int ret; 1333bd7c4b50SAl Viro 1334db3c9adeSAl Viro path->mnt = nd->path.mnt; 1335db3c9adeSAl Viro path->dentry = dentry; 1336c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1337c153007bSAl Viro unsigned int seq = *seqp; 1338c153007bSAl Viro if (unlikely(!*inode)) 1339c153007bSAl Viro return -ENOENT; 1340c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 13419deed3ebSAl Viro return 0; 1342c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1343c153007bSAl Viro return -ECHILD; 1344c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1345c153007bSAl Viro path->mnt = nd->path.mnt; 1346c153007bSAl Viro path->dentry = dentry; 1347c153007bSAl Viro } 13489deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 13499deed3ebSAl Viro if (jumped) { 13509deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 13519deed3ebSAl Viro ret = -EXDEV; 13529deed3ebSAl Viro else 13539deed3ebSAl Viro nd->flags |= LOOKUP_JUMPED; 13549deed3ebSAl Viro } 13559deed3ebSAl Viro if (unlikely(ret)) { 13569deed3ebSAl Viro dput(path->dentry); 13579deed3ebSAl Viro if (path->mnt != nd->path.mnt) 13589deed3ebSAl Viro mntput(path->mnt); 13599deed3ebSAl Viro } else { 1360bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1361bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1362bd7c4b50SAl Viro } 1363bd7c4b50SAl Viro return ret; 1364bd7c4b50SAl Viro } 1365bd7c4b50SAl Viro 13669875cf80SDavid Howells /* 13679875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 13689875cf80SDavid Howells */ 13699875cf80SDavid Howells static void follow_mount(struct path *path) 13709875cf80SDavid Howells { 13719875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 13729875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 13739875cf80SDavid Howells if (!mounted) 13749875cf80SDavid Howells break; 13759875cf80SDavid Howells dput(path->dentry); 13769875cf80SDavid Howells mntput(path->mnt); 13779875cf80SDavid Howells path->mnt = mounted; 13789875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 13799875cf80SDavid Howells } 13809875cf80SDavid Howells } 13819875cf80SDavid Howells 13821da177e4SLinus Torvalds /* 1383f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1384f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1385baa03890SNick Piggin */ 1386e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1387e3c13928SAl Viro struct dentry *dir, 13886c51e513SAl Viro unsigned int flags) 1389baa03890SNick Piggin { 1390a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1391bad61189SMiklos Szeredi if (dentry) { 1392a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1393bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 139474ff0ffcSAl Viro if (!error) 13955542aa2fSEric W. Biederman d_invalidate(dentry); 1396bad61189SMiklos Szeredi dput(dentry); 139774ff0ffcSAl Viro return ERR_PTR(error); 1398bad61189SMiklos Szeredi } 1399bad61189SMiklos Szeredi } 1400baa03890SNick Piggin return dentry; 1401baa03890SNick Piggin } 1402baa03890SNick Piggin 1403baa03890SNick Piggin /* 1404a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1405a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1406a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1407a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1408a03ece5fSAl Viro * at all. 140944396f4bSJosef Bacik */ 1410a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1411a03ece5fSAl Viro struct dentry *base, unsigned int flags) 141244396f4bSJosef Bacik { 1413a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 141444396f4bSJosef Bacik struct dentry *old; 1415a03ece5fSAl Viro struct inode *dir = base->d_inode; 1416a03ece5fSAl Viro 1417a03ece5fSAl Viro if (dentry) 1418a03ece5fSAl Viro return dentry; 141944396f4bSJosef Bacik 142044396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1421a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 142244396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1423a03ece5fSAl Viro 1424a03ece5fSAl Viro dentry = d_alloc(base, name); 1425a03ece5fSAl Viro if (unlikely(!dentry)) 1426a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 142744396f4bSJosef Bacik 142872bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 142944396f4bSJosef Bacik if (unlikely(old)) { 143044396f4bSJosef Bacik dput(dentry); 143144396f4bSJosef Bacik dentry = old; 143244396f4bSJosef Bacik } 143344396f4bSJosef Bacik return dentry; 143444396f4bSJosef Bacik } 143544396f4bSJosef Bacik 143620e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 143720e34357SAl Viro struct inode **inode, 1438254cf582SAl Viro unsigned *seqp) 14391da177e4SLinus Torvalds { 144031e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14415a18fff2SAl Viro int status = 1; 14429875cf80SDavid Howells 14433cac260aSAl Viro /* 1444b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 14455d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 14465d0f49c1SAl Viro * going to fall back to non-racy lookup. 1447b04f784eSNick Piggin */ 144831e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 144931e6b01fSNick Piggin unsigned seq; 1450da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14515d0f49c1SAl Viro if (unlikely(!dentry)) { 14524675ac39SAl Viro if (unlazy_walk(nd)) 145320e34357SAl Viro return ERR_PTR(-ECHILD); 145420e34357SAl Viro return NULL; 14555d0f49c1SAl Viro } 14565a18fff2SAl Viro 145712f8ad4bSLinus Torvalds /* 145812f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 145912f8ad4bSLinus Torvalds * the dentry name information from lookup. 146012f8ad4bSLinus Torvalds */ 146163afdfc7SDavid Howells *inode = d_backing_inode(dentry); 14625d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 146320e34357SAl Viro return ERR_PTR(-ECHILD); 146412f8ad4bSLinus Torvalds 146512f8ad4bSLinus Torvalds /* 146612f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 146712f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 146812f8ad4bSLinus Torvalds * 146912f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 147012f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 147112f8ad4bSLinus Torvalds */ 14725d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 147320e34357SAl Viro return ERR_PTR(-ECHILD); 14745a18fff2SAl Viro 1475254cf582SAl Viro *seqp = seq; 14764ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1477c153007bSAl Viro if (likely(status > 0)) 147820e34357SAl Viro return dentry; 14794675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 148020e34357SAl Viro return ERR_PTR(-ECHILD); 1481209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1482209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1483209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 14845a18fff2SAl Viro } else { 1485e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 148681e6f520SAl Viro if (unlikely(!dentry)) 148720e34357SAl Viro return NULL; 14884ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14895d0f49c1SAl Viro } 14905a18fff2SAl Viro if (unlikely(status <= 0)) { 1491e9742b53SAl Viro if (!status) 14925d0f49c1SAl Viro d_invalidate(dentry); 14935a18fff2SAl Viro dput(dentry); 149420e34357SAl Viro return ERR_PTR(status); 14955a18fff2SAl Viro } 149620e34357SAl Viro return dentry; 1497697f514dSMiklos Szeredi } 1498697f514dSMiklos Szeredi 1499697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 150088d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1501e3c13928SAl Viro struct dentry *dir, 1502e3c13928SAl Viro unsigned int flags) 1503697f514dSMiklos Szeredi { 150488d8331aSAl Viro struct dentry *dentry, *old; 15051936386eSAl Viro struct inode *inode = dir->d_inode; 1506d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15071936386eSAl Viro 15081936386eSAl Viro /* Don't go there if it's already dead */ 150994bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 151088d8331aSAl Viro return ERR_PTR(-ENOENT); 151194bdd655SAl Viro again: 1512d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 151394bdd655SAl Viro if (IS_ERR(dentry)) 151488d8331aSAl Viro return dentry; 151594bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1516949a852eSAl Viro int error = d_revalidate(dentry, flags); 1517949a852eSAl Viro if (unlikely(error <= 0)) { 151894bdd655SAl Viro if (!error) { 1519949a852eSAl Viro d_invalidate(dentry); 1520949a852eSAl Viro dput(dentry); 152194bdd655SAl Viro goto again; 152294bdd655SAl Viro } 152394bdd655SAl Viro dput(dentry); 1524949a852eSAl Viro dentry = ERR_PTR(error); 1525949a852eSAl Viro } 152694bdd655SAl Viro } else { 15271936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 152885c7f810SAl Viro d_lookup_done(dentry); 15291936386eSAl Viro if (unlikely(old)) { 15301936386eSAl Viro dput(dentry); 15311936386eSAl Viro dentry = old; 1532949a852eSAl Viro } 1533949a852eSAl Viro } 1534e3c13928SAl Viro return dentry; 15351da177e4SLinus Torvalds } 15361da177e4SLinus Torvalds 153788d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 153888d8331aSAl Viro struct dentry *dir, 153988d8331aSAl Viro unsigned int flags) 154088d8331aSAl Viro { 154188d8331aSAl Viro struct inode *inode = dir->d_inode; 154288d8331aSAl Viro struct dentry *res; 154388d8331aSAl Viro inode_lock_shared(inode); 154488d8331aSAl Viro res = __lookup_slow(name, dir, flags); 154588d8331aSAl Viro inode_unlock_shared(inode); 154688d8331aSAl Viro return res; 154788d8331aSAl Viro } 154888d8331aSAl Viro 154952094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 155052094c8aSAl Viro { 155152094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15524ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 155352094c8aSAl Viro if (err != -ECHILD) 155452094c8aSAl Viro return err; 15554675ac39SAl Viro if (unlazy_walk(nd)) 155652094c8aSAl Viro return -ECHILD; 155752094c8aSAl Viro } 15584ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 155952094c8aSAl Viro } 156052094c8aSAl Viro 1561b1a81972SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 1562b1a81972SAl Viro 156306708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1564b1a81972SAl Viro struct inode *inode, unsigned seq, int flags) 1565d63ff28fSAl Viro { 15661cf2665bSAl Viro struct saved *last; 1567ad6cc4c3SAl Viro const char *res; 1568ad6cc4c3SAl Viro int error; 1569ad6cc4c3SAl Viro 1570756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1571626de996SAl Viro path_to_nameidata(link, nd); 157206708adbSAl Viro return ERR_PTR(-ELOOP); 1573626de996SAl Viro } 1574bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1575cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1576cd179f44SAl Viro mntget(link->mnt); 15777973387aSAl Viro } 1578626de996SAl Viro error = nd_alloc_stack(nd); 1579626de996SAl Viro if (unlikely(error)) { 1580bc40aee0SAl Viro if (error == -ECHILD) { 1581ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1582ad1633a1SAl Viro drop_links(nd); 1583ad1633a1SAl Viro nd->depth = 0; 1584ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1585ad1633a1SAl Viro nd->path.mnt = NULL; 1586ad1633a1SAl Viro nd->path.dentry = NULL; 1587ad1633a1SAl Viro rcu_read_unlock(); 15884675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1589bc40aee0SAl Viro error = nd_alloc_stack(nd); 1590bc40aee0SAl Viro } 1591bc40aee0SAl Viro if (error) { 1592cd179f44SAl Viro path_put(link); 159306708adbSAl Viro return ERR_PTR(error); 1594626de996SAl Viro } 1595bc40aee0SAl Viro } 1596626de996SAl Viro 1597ab104923SAl Viro last = nd->stack + nd->depth++; 15981cf2665bSAl Viro last->link = *link; 1599fceef393SAl Viro clear_delayed_call(&last->done); 16000450b2d1SAl Viro last->seq = seq; 1601ad6cc4c3SAl Viro 1602b1a81972SAl Viro if (flags & WALK_TRAILING) { 1603ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1604ad6cc4c3SAl Viro if (unlikely(error)) 1605ad6cc4c3SAl Viro return ERR_PTR(error); 1606ad6cc4c3SAl Viro } 1607ad6cc4c3SAl Viro 1608ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1609ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1610ad6cc4c3SAl Viro 1611ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1612ad6cc4c3SAl Viro touch_atime(&last->link); 1613ad6cc4c3SAl Viro cond_resched(); 1614ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1615ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1616ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1617ad6cc4c3SAl Viro touch_atime(&last->link); 1618ad6cc4c3SAl Viro } 1619ad6cc4c3SAl Viro 1620ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1621ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1622ad6cc4c3SAl Viro if (unlikely(error)) 1623ad6cc4c3SAl Viro return ERR_PTR(error); 1624ad6cc4c3SAl Viro 1625ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1626ad6cc4c3SAl Viro if (!res) { 1627ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1628ad6cc4c3SAl Viro struct delayed_call *); 1629ad6cc4c3SAl Viro get = inode->i_op->get_link; 1630ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1631ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1632ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1633ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1634ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1635ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1636ad6cc4c3SAl Viro } 1637ad6cc4c3SAl Viro } else { 1638ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1639ad6cc4c3SAl Viro } 1640ad6cc4c3SAl Viro if (!res) 1641ad6cc4c3SAl Viro goto all_done; 1642ad6cc4c3SAl Viro if (IS_ERR(res)) 1643ad6cc4c3SAl Viro return res; 1644ad6cc4c3SAl Viro } 1645ad6cc4c3SAl Viro if (*res == '/') { 1646ad6cc4c3SAl Viro error = nd_jump_root(nd); 1647ad6cc4c3SAl Viro if (unlikely(error)) 1648ad6cc4c3SAl Viro return ERR_PTR(error); 1649ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1650ad6cc4c3SAl Viro ; 1651ad6cc4c3SAl Viro } 1652ad6cc4c3SAl Viro if (*res) 1653ad6cc4c3SAl Viro return res; 1654ad6cc4c3SAl Viro all_done: // pure jump 1655ad6cc4c3SAl Viro put_link(nd); 1656ad6cc4c3SAl Viro return NULL; 1657d63ff28fSAl Viro } 1658d63ff28fSAl Viro 16593ddcd056SLinus Torvalds /* 16603ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16613ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16623ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16633ddcd056SLinus Torvalds * for the common case. 16643ddcd056SLinus Torvalds */ 1665b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1666cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 16673ddcd056SLinus Torvalds { 1668cbae4d12SAl Viro struct path path; 1669cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1670cbae4d12SAl Viro 1671cbae4d12SAl Viro if (err < 0) 1672b0417d2cSAl Viro return ERR_PTR(err); 1673cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 16748c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1675aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 16768f64fb1cSAl Viro /* not a symlink or should not follow */ 1677cbae4d12SAl Viro path_to_nameidata(&path, nd); 16788f64fb1cSAl Viro nd->inode = inode; 16798f64fb1cSAl Viro nd->seq = seq; 1680b0417d2cSAl Viro return NULL; 16818f64fb1cSAl Viro } 1682a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1683a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1684cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1685b0417d2cSAl Viro return ERR_PTR(-ECHILD); 1686a7f77542SAl Viro } 1687b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 16883ddcd056SLinus Torvalds } 16893ddcd056SLinus Torvalds 1690c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1691c2df1968SAl Viro struct inode **inodep, 1692c2df1968SAl Viro unsigned *seqp) 1693957dd41dSAl Viro { 169412487f30SAl Viro struct dentry *parent, *old; 1695957dd41dSAl Viro 169612487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 169712487f30SAl Viro goto in_root; 169812487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 1699efe772d6SAl Viro struct path path = nd->path; 1700efe772d6SAl Viro unsigned seq; 1701efe772d6SAl Viro 170212487f30SAl Viro while (1) { 1703efe772d6SAl Viro struct mount *mnt = real_mount(path.mnt); 1704957dd41dSAl Viro struct mount *mparent = mnt->mnt_parent; 1705957dd41dSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1706efe772d6SAl Viro seq = read_seqcount_begin(&mountpoint->d_seq); 1707efe772d6SAl Viro if (&mparent->mnt == path.mnt) 170812487f30SAl Viro goto in_root; 1709efe772d6SAl Viro path.dentry = mountpoint; 1710efe772d6SAl Viro path.mnt = &mparent->mnt; 1711efe772d6SAl Viro if (path_equal(&path, &nd->root)) 171212487f30SAl Viro goto in_root; 1713efe772d6SAl Viro if (path.dentry != path.mnt->mnt_root) 171412487f30SAl Viro break; 1715957dd41dSAl Viro } 1716efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1717efe772d6SAl Viro return ERR_PTR(-ECHILD); 1718efe772d6SAl Viro nd->path = path; 1719efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1720efe772d6SAl Viro nd->seq = seq; 1721efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1722efe772d6SAl Viro return ERR_PTR(-ECHILD); 1723efe772d6SAl Viro /* we know that mountpoint was pinned */ 1724957dd41dSAl Viro } 172512487f30SAl Viro old = nd->path.dentry; 172612487f30SAl Viro parent = old->d_parent; 172712487f30SAl Viro *inodep = parent->d_inode; 172812487f30SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 172912487f30SAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 173012487f30SAl Viro return ERR_PTR(-ECHILD); 173112487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 173212487f30SAl Viro return ERR_PTR(-ECHILD); 173312487f30SAl Viro return parent; 173412487f30SAl Viro in_root: 1735efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1736efe772d6SAl Viro return ERR_PTR(-ECHILD); 1737957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17387521f22bSAl Viro return ERR_PTR(-ECHILD); 1739c2df1968SAl Viro return NULL; 1740957dd41dSAl Viro } 1741957dd41dSAl Viro 1742c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1743c2df1968SAl Viro struct inode **inodep, 1744c2df1968SAl Viro unsigned *seqp) 1745957dd41dSAl Viro { 174612487f30SAl Viro struct dentry *parent; 174712487f30SAl Viro 1748957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 174912487f30SAl Viro goto in_root; 175012487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 1751165200d6SAl Viro struct path path = nd->path; 1752165200d6SAl Viro path_get(&path); 175312487f30SAl Viro while (1) { 1754165200d6SAl Viro if (!follow_up(&path)) { 1755165200d6SAl Viro path_put(&path); 175612487f30SAl Viro goto in_root; 1757165200d6SAl Viro } 1758165200d6SAl Viro if (path_equal(&path, &nd->root)) { 1759165200d6SAl Viro path_put(&path); 176012487f30SAl Viro goto in_root; 1761165200d6SAl Viro } 1762165200d6SAl Viro if (path.dentry != nd->path.mnt->mnt_root) 1763957dd41dSAl Viro break; 176412487f30SAl Viro } 1765165200d6SAl Viro path_put(&nd->path); 1766165200d6SAl Viro nd->path = path; 1767165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1768165200d6SAl Viro return ERR_PTR(-EXDEV); 176912487f30SAl Viro } 1770957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 177112487f30SAl Viro parent = dget_parent(nd->path.dentry); 1772957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1773957dd41dSAl Viro dput(parent); 17747521f22bSAl Viro return ERR_PTR(-ENOENT); 1775957dd41dSAl Viro } 1776c2df1968SAl Viro *seqp = 0; 1777c2df1968SAl Viro *inodep = parent->d_inode; 1778c2df1968SAl Viro return parent; 177912487f30SAl Viro 178012487f30SAl Viro in_root: 1781957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17827521f22bSAl Viro return ERR_PTR(-EXDEV); 1783c2df1968SAl Viro dget(nd->path.dentry); 1784c2df1968SAl Viro return NULL; 1785957dd41dSAl Viro } 1786957dd41dSAl Viro 17877521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1788957dd41dSAl Viro { 1789957dd41dSAl Viro if (type == LAST_DOTDOT) { 17907521f22bSAl Viro const char *error = NULL; 1791c2df1968SAl Viro struct dentry *parent; 1792c2df1968SAl Viro struct inode *inode; 1793c2df1968SAl Viro unsigned seq; 1794957dd41dSAl Viro 1795957dd41dSAl Viro if (!nd->root.mnt) { 17967521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1797957dd41dSAl Viro if (error) 1798957dd41dSAl Viro return error; 1799957dd41dSAl Viro } 1800957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1801c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1802957dd41dSAl Viro else 1803c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1804c2df1968SAl Viro if (IS_ERR(parent)) 1805c2df1968SAl Viro return ERR_CAST(parent); 1806c2df1968SAl Viro if (unlikely(!parent)) 1807c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1808c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1809c2df1968SAl Viro else 1810c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1811c2df1968SAl Viro parent, inode, seq); 1812c2df1968SAl Viro if (unlikely(error)) 1813957dd41dSAl Viro return error; 1814957dd41dSAl Viro 1815957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1816957dd41dSAl Viro /* 1817957dd41dSAl Viro * If there was a racing rename or mount along our 1818957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1819957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1820957dd41dSAl Viro * some fallback). 1821957dd41dSAl Viro */ 1822957dd41dSAl Viro smp_rmb(); 1823957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 18247521f22bSAl Viro return ERR_PTR(-EAGAIN); 1825957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 18267521f22bSAl Viro return ERR_PTR(-EAGAIN); 1827957dd41dSAl Viro } 1828957dd41dSAl Viro } 18297521f22bSAl Viro return NULL; 1830957dd41dSAl Viro } 1831957dd41dSAl Viro 183292d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1833ce57dfc1SAl Viro { 1834db3c9adeSAl Viro struct dentry *dentry; 1835ce57dfc1SAl Viro struct inode *inode; 1836254cf582SAl Viro unsigned seq; 1837ce57dfc1SAl Viro /* 1838ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1839ce57dfc1SAl Viro * to be able to know about the current root directory and 1840ce57dfc1SAl Viro * parent relationships. 1841ce57dfc1SAl Viro */ 18424693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18431c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18444693a547SAl Viro put_link(nd); 18457521f22bSAl Viro return handle_dots(nd, nd->last_type); 18464693a547SAl Viro } 184720e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 184820e34357SAl Viro if (IS_ERR(dentry)) 184992d27016SAl Viro return ERR_CAST(dentry); 185020e34357SAl Viro if (unlikely(!dentry)) { 1851db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1852db3c9adeSAl Viro if (IS_ERR(dentry)) 185392d27016SAl Viro return ERR_CAST(dentry); 185420e34357SAl Viro } 185556676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 185656676ec3SAl Viro put_link(nd); 1857b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1858ce57dfc1SAl Viro } 1859ce57dfc1SAl Viro 18601da177e4SLinus Torvalds /* 1861bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1862bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1863bfcfaa77SLinus Torvalds * 1864bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1865bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1866bfcfaa77SLinus Torvalds * fast. 1867bfcfaa77SLinus Torvalds * 1868bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1869bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1870bfcfaa77SLinus Torvalds * crossing operation. 1871bfcfaa77SLinus Torvalds * 1872bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1873bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1874bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1875bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1876bfcfaa77SLinus Torvalds */ 1877bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1878bfcfaa77SLinus Torvalds 1879f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1880bfcfaa77SLinus Torvalds 1881468a9428SGeorge Spelvin #ifdef HASH_MIX 1882bfcfaa77SLinus Torvalds 1883468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1884468a9428SGeorge Spelvin 1885468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18862a18da7aSGeorge Spelvin /* 18872a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18882a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18892a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18902a18da7aSGeorge Spelvin * and no temporaries. 18912a18da7aSGeorge Spelvin * 18922a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18932a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18942a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18952a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18962a18da7aSGeorge Spelvin * 18972a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18982a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18992a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19002a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19012a18da7aSGeorge Spelvin * 19022a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19032a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19042a18da7aSGeorge Spelvin * toggling any given output bit. 19052a18da7aSGeorge Spelvin * 19062a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19072a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19082a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19092a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19102a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19112a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19122a18da7aSGeorge Spelvin * Perfect: 8192 258048 19132a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19142a18da7aSGeorge Spelvin */ 19152a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19162a18da7aSGeorge Spelvin ( x ^= (a), \ 19172a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19182a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19192a18da7aSGeorge Spelvin y *= 9 ) 1920bfcfaa77SLinus Torvalds 19210fed3ac8SGeorge Spelvin /* 19222a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19232a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19242a18da7aSGeorge Spelvin * work done before the hash value is used. 19250fed3ac8SGeorge Spelvin */ 19262a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19270fed3ac8SGeorge Spelvin { 19282a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19292a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19302a18da7aSGeorge Spelvin return y >> 32; 19310fed3ac8SGeorge Spelvin } 19320fed3ac8SGeorge Spelvin 1933bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1934bfcfaa77SLinus Torvalds 19352a18da7aSGeorge Spelvin /* 19362a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19372a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19382a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19392a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19402a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19412a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19422a18da7aSGeorge Spelvin * Perfect: 2048 31744 19432a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19442a18da7aSGeorge Spelvin */ 19452a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19462a18da7aSGeorge Spelvin ( x ^= (a), \ 19472a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19482a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19492a18da7aSGeorge Spelvin y *= 9 ) 1950bfcfaa77SLinus Torvalds 19512a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19520fed3ac8SGeorge Spelvin { 19532a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19542a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19550fed3ac8SGeorge Spelvin } 19560fed3ac8SGeorge Spelvin 1957bfcfaa77SLinus Torvalds #endif 1958bfcfaa77SLinus Torvalds 19592a18da7aSGeorge Spelvin /* 19602a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19612a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19622a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19632a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19642a18da7aSGeorge Spelvin * finds the delimiter after the name. 19652a18da7aSGeorge Spelvin */ 19668387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1967bfcfaa77SLinus Torvalds { 19688387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1969bfcfaa77SLinus Torvalds 1970bfcfaa77SLinus Torvalds for (;;) { 1971fcfd2fbfSGeorge Spelvin if (!len) 1972fcfd2fbfSGeorge Spelvin goto done; 1973e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1974bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1975bfcfaa77SLinus Torvalds break; 19762a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1977bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1978bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1979bfcfaa77SLinus Torvalds } 19802a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1981bfcfaa77SLinus Torvalds done: 19822a18da7aSGeorge Spelvin return fold_hash(x, y); 1983bfcfaa77SLinus Torvalds } 1984bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1985bfcfaa77SLinus Torvalds 1986fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19878387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1988fcfd2fbfSGeorge Spelvin { 19898387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19908387ff25SLinus Torvalds unsigned long adata, mask, len; 1991fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1992fcfd2fbfSGeorge Spelvin 19938387ff25SLinus Torvalds len = 0; 19948387ff25SLinus Torvalds goto inside; 19958387ff25SLinus Torvalds 1996fcfd2fbfSGeorge Spelvin do { 19972a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1998fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19998387ff25SLinus Torvalds inside: 2000fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2001fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2002fcfd2fbfSGeorge Spelvin 2003fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2004fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20052a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2006fcfd2fbfSGeorge Spelvin 20072a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2008fcfd2fbfSGeorge Spelvin } 2009fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2010fcfd2fbfSGeorge Spelvin 2011bfcfaa77SLinus Torvalds /* 2012bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2013d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2014bfcfaa77SLinus Torvalds */ 20158387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2016bfcfaa77SLinus Torvalds { 20178387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20188387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 201936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2020bfcfaa77SLinus Torvalds 20218387ff25SLinus Torvalds len = 0; 20228387ff25SLinus Torvalds goto inside; 20238387ff25SLinus Torvalds 2024bfcfaa77SLinus Torvalds do { 20252a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2026bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20278387ff25SLinus Torvalds inside: 2028e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 202936126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 203036126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2031bfcfaa77SLinus Torvalds 203236126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 203336126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 203436126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20352a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 203636126f8fSLinus Torvalds 20372a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2038bfcfaa77SLinus Torvalds } 2039bfcfaa77SLinus Torvalds 20402a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2041bfcfaa77SLinus Torvalds 2042fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20438387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20440145acc2SLinus Torvalds { 20458387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20460145acc2SLinus Torvalds while (len--) 2047fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20480145acc2SLinus Torvalds return end_name_hash(hash); 20490145acc2SLinus Torvalds } 2050ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20510145acc2SLinus Torvalds 2052fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20538387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2054fcfd2fbfSGeorge Spelvin { 20558387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2056fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2057fcfd2fbfSGeorge Spelvin 2058fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2059e0ab7af9SGeorge Spelvin while (c) { 2060fcfd2fbfSGeorge Spelvin len++; 2061fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2062fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2063e0ab7af9SGeorge Spelvin } 2064fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2065fcfd2fbfSGeorge Spelvin } 2066f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2067fcfd2fbfSGeorge Spelvin 20683ddcd056SLinus Torvalds /* 2069200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2070200e9ef7SLinus Torvalds * one character. 2071200e9ef7SLinus Torvalds */ 20728387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2073200e9ef7SLinus Torvalds { 20748387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2075200e9ef7SLinus Torvalds unsigned long len = 0, c; 2076200e9ef7SLinus Torvalds 2077200e9ef7SLinus Torvalds c = (unsigned char)*name; 2078200e9ef7SLinus Torvalds do { 2079200e9ef7SLinus Torvalds len++; 2080200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2081200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2082200e9ef7SLinus Torvalds } while (c && c != '/'); 2083d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2084200e9ef7SLinus Torvalds } 2085200e9ef7SLinus Torvalds 2086bfcfaa77SLinus Torvalds #endif 2087bfcfaa77SLinus Torvalds 2088200e9ef7SLinus Torvalds /* 20891da177e4SLinus Torvalds * Name resolution. 2090ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2091ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20921da177e4SLinus Torvalds * 2093ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2094ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20951da177e4SLinus Torvalds */ 20966de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20971da177e4SLinus Torvalds { 2098d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 20991da177e4SLinus Torvalds int err; 21001da177e4SLinus Torvalds 2101b4c03536SAl Viro nd->last_type = LAST_ROOT; 2102c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 21039b5858e9SAl Viro if (IS_ERR(name)) 21049b5858e9SAl Viro return PTR_ERR(name); 21051da177e4SLinus Torvalds while (*name=='/') 21061da177e4SLinus Torvalds name++; 21071da177e4SLinus Torvalds if (!*name) 21089e18f10aSAl Viro return 0; 21091da177e4SLinus Torvalds 21101da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21111da177e4SLinus Torvalds for(;;) { 211292d27016SAl Viro const char *link; 2113d6bb3e90SLinus Torvalds u64 hash_len; 2114fe479a58SAl Viro int type; 21151da177e4SLinus Torvalds 211652094c8aSAl Viro err = may_lookup(nd); 21171da177e4SLinus Torvalds if (err) 21183595e234SAl Viro return err; 21191da177e4SLinus Torvalds 21208387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21211da177e4SLinus Torvalds 2122fe479a58SAl Viro type = LAST_NORM; 2123d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2124fe479a58SAl Viro case 2: 2125200e9ef7SLinus Torvalds if (name[1] == '.') { 2126fe479a58SAl Viro type = LAST_DOTDOT; 212716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 212816c2cd71SAl Viro } 2129fe479a58SAl Viro break; 2130fe479a58SAl Viro case 1: 2131fe479a58SAl Viro type = LAST_DOT; 2132fe479a58SAl Viro } 21335a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21345a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 213516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21365a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2137a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2138da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21395a202bcdSAl Viro if (err < 0) 21403595e234SAl Viro return err; 2141d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2142d6bb3e90SLinus Torvalds name = this.name; 21435a202bcdSAl Viro } 21445a202bcdSAl Viro } 2145fe479a58SAl Viro 2146d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2147d6bb3e90SLinus Torvalds nd->last.name = name; 21485f4a6a69SAl Viro nd->last_type = type; 21495f4a6a69SAl Viro 2150d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2151d6bb3e90SLinus Torvalds if (!*name) 2152bdf6cbf1SAl Viro goto OK; 2153200e9ef7SLinus Torvalds /* 2154200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2155200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2156200e9ef7SLinus Torvalds */ 2157200e9ef7SLinus Torvalds do { 2158d6bb3e90SLinus Torvalds name++; 2159d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21608620c238SAl Viro if (unlikely(!*name)) { 21618620c238SAl Viro OK: 2162d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2163c108837eSAl Viro if (!depth) { 2164c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 21658620c238SAl Viro return 0; 2166c108837eSAl Viro } 21678620c238SAl Viro /* last component of nested symlink */ 2168d8d4611aSAl Viro name = nd->stack[--depth].name; 21698c4efe22SAl Viro link = walk_component(nd, 0); 21701c4ff1a8SAl Viro } else { 21711c4ff1a8SAl Viro /* not the last component */ 21728c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 21738620c238SAl Viro } 217492d27016SAl Viro if (unlikely(link)) { 217592d27016SAl Viro if (IS_ERR(link)) 217692d27016SAl Viro return PTR_ERR(link); 217792d27016SAl Viro /* a symlink to follow */ 2178d8d4611aSAl Viro nd->stack[depth++].name = name; 217992d27016SAl Viro name = link; 21809e18f10aSAl Viro continue; 218148c8b0c5SAl Viro } 218297242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 218397242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21844675ac39SAl Viro if (unlazy_walk(nd)) 218597242f99SAl Viro return -ECHILD; 218697242f99SAl Viro } 21873595e234SAl Viro return -ENOTDIR; 21885f4a6a69SAl Viro } 2189ce57dfc1SAl Viro } 219097242f99SAl Viro } 21911da177e4SLinus Torvalds 2192edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2193c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 219431e6b01fSNick Piggin { 2195740a1678SAleksa Sarai int error; 2196c8a53ee5SAl Viro const char *s = nd->name->name; 219731e6b01fSNick Piggin 2198c0eb027eSLinus Torvalds if (!*s) 2199c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2200edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2201edc2b1daSAl Viro rcu_read_lock(); 2202c0eb027eSLinus Torvalds 2203c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 220431e6b01fSNick Piggin nd->depth = 0; 2205ab87f9a5SAleksa Sarai 2206ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2207ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2208ab87f9a5SAleksa Sarai smp_rmb(); 2209ab87f9a5SAleksa Sarai 22105b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2211b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2212b18825a7SDavid Howells struct inode *inode = root->d_inode; 221393893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2214368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22155b6ca027SAl Viro nd->path = nd->root; 22165b6ca027SAl Viro nd->inode = inode; 22175b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2218ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22198f47a016SAl Viro nd->root_seq = nd->seq; 22205b6ca027SAl Viro } else { 22215b6ca027SAl Viro path_get(&nd->path); 22225b6ca027SAl Viro } 2223368ee9baSAl Viro return s; 22245b6ca027SAl Viro } 22255b6ca027SAl Viro 222631e6b01fSNick Piggin nd->root.mnt = NULL; 2227248fb5b9SAl Viro nd->path.mnt = NULL; 2228248fb5b9SAl Viro nd->path.dentry = NULL; 222931e6b01fSNick Piggin 22308db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22318db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2232740a1678SAleksa Sarai error = nd_jump_root(nd); 2233740a1678SAleksa Sarai if (unlikely(error)) 2234740a1678SAleksa Sarai return ERR_PTR(error); 2235ef55d917SAl Viro return s; 22368db52c7eSAleksa Sarai } 22378db52c7eSAleksa Sarai 22388db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22398db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2240e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 224131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2242c28cc364SNick Piggin unsigned seq; 224331e6b01fSNick Piggin 2244c28cc364SNick Piggin do { 2245c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 224631e6b01fSNick Piggin nd->path = fs->pwd; 2247ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2248c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2249c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2250e41f7d4eSAl Viro } else { 2251e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2252ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2253e41f7d4eSAl Viro } 225431e6b01fSNick Piggin } else { 2255582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2256c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 225731e6b01fSNick Piggin struct dentry *dentry; 225831e6b01fSNick Piggin 22592903ff01SAl Viro if (!f.file) 2260368ee9baSAl Viro return ERR_PTR(-EBADF); 226131e6b01fSNick Piggin 22622903ff01SAl Viro dentry = f.file->f_path.dentry; 226331e6b01fSNick Piggin 2264edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22652903ff01SAl Viro fdput(f); 2266368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2267f52e0c11SAl Viro } 22682903ff01SAl Viro 22692903ff01SAl Viro nd->path = f.file->f_path; 2270e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 227134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 227234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22735590ff0dSUlrich Drepper } else { 22742903ff01SAl Viro path_get(&nd->path); 227534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22761da177e4SLinus Torvalds } 227734a26b99SAl Viro fdput(f); 2278e41f7d4eSAl Viro } 22798db52c7eSAleksa Sarai 2280adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2281adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2282adb21d2bSAleksa Sarai nd->root = nd->path; 2283adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2284adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2285adb21d2bSAleksa Sarai } else { 2286adb21d2bSAleksa Sarai path_get(&nd->root); 2287adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2288adb21d2bSAleksa Sarai } 2289adb21d2bSAleksa Sarai } 2290adb21d2bSAleksa Sarai return s; 22919b4a9b14SAl Viro } 22929b4a9b14SAl Viro 22931ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 229495fa25d9SAl Viro { 2295bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2296bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2297bd92d7feSAl Viro 2298c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2299bd92d7feSAl Viro } 2300bd92d7feSAl Viro 23014f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23024f757f3cSAl Viro { 2303c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2304db3c9adeSAl Viro dget(nd->path.dentry); 2305b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2306b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23074f757f3cSAl Viro } 23084f757f3cSAl Viro 23099b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2310c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23119b4a9b14SAl Viro { 2312c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2313bd92d7feSAl Viro int err; 231431e6b01fSNick Piggin 23159b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23164f757f3cSAl Viro err = handle_lookup_down(nd); 23175f336e72SAl Viro if (unlikely(err < 0)) 23185f336e72SAl Viro s = ERR_PTR(err); 23194f757f3cSAl Viro } 23204f757f3cSAl Viro 23211ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23221ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23231ccac622SAl Viro ; 23249f1fafeeSAl Viro if (!err) 23259f1fafeeSAl Viro err = complete_walk(nd); 2326bd92d7feSAl Viro 2327deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2328deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2329bd23a539SAl Viro err = -ENOTDIR; 2330161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2331161aff1dSAl Viro err = handle_lookup_down(nd); 2332161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2333161aff1dSAl Viro } 2334625b6d10SAl Viro if (!err) { 2335625b6d10SAl Viro *path = nd->path; 2336625b6d10SAl Viro nd->path.mnt = NULL; 2337625b6d10SAl Viro nd->path.dentry = NULL; 2338625b6d10SAl Viro } 2339deb106c6SAl Viro terminate_walk(nd); 2340bd92d7feSAl Viro return err; 234131e6b01fSNick Piggin } 234231e6b01fSNick Piggin 234331d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23449ad1aaa6SAl Viro struct path *path, struct path *root) 2345873f1eedSJeff Layton { 2346894bc8c4SAl Viro int retval; 23479883d185SAl Viro struct nameidata nd; 2348abc9f5beSAl Viro if (IS_ERR(name)) 2349abc9f5beSAl Viro return PTR_ERR(name); 23509ad1aaa6SAl Viro if (unlikely(root)) { 23519ad1aaa6SAl Viro nd.root = *root; 23529ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23539ad1aaa6SAl Viro } 23549883d185SAl Viro set_nameidata(&nd, dfd, name); 2355c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2356873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2357c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2358873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2359c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2360873f1eedSJeff Layton 2361873f1eedSJeff Layton if (likely(!retval)) 2362161aff1dSAl Viro audit_inode(name, path->dentry, 2363161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23649883d185SAl Viro restore_nameidata(); 2365e4bd1c1aSAl Viro putname(name); 2366873f1eedSJeff Layton return retval; 2367873f1eedSJeff Layton } 2368873f1eedSJeff Layton 23698bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2370c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2371391172c4SAl Viro struct path *parent) 23728bcb77faSAl Viro { 2373c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23749b5858e9SAl Viro int err = link_path_walk(s, nd); 23758bcb77faSAl Viro if (!err) 23768bcb77faSAl Viro err = complete_walk(nd); 2377391172c4SAl Viro if (!err) { 2378391172c4SAl Viro *parent = nd->path; 2379391172c4SAl Viro nd->path.mnt = NULL; 2380391172c4SAl Viro nd->path.dentry = NULL; 2381391172c4SAl Viro } 2382deb106c6SAl Viro terminate_walk(nd); 23838bcb77faSAl Viro return err; 23848bcb77faSAl Viro } 23858bcb77faSAl Viro 23865c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2387391172c4SAl Viro unsigned int flags, struct path *parent, 2388391172c4SAl Viro struct qstr *last, int *type) 23898bcb77faSAl Viro { 23908bcb77faSAl Viro int retval; 23919883d185SAl Viro struct nameidata nd; 23928bcb77faSAl Viro 23935c31b6ceSAl Viro if (IS_ERR(name)) 23945c31b6ceSAl Viro return name; 23959883d185SAl Viro set_nameidata(&nd, dfd, name); 2396c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23978bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2398c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23998bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2400c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2401391172c4SAl Viro if (likely(!retval)) { 2402391172c4SAl Viro *last = nd.last; 2403391172c4SAl Viro *type = nd.last_type; 2404c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24055c31b6ceSAl Viro } else { 24065c31b6ceSAl Viro putname(name); 24075c31b6ceSAl Viro name = ERR_PTR(retval); 2408391172c4SAl Viro } 24099883d185SAl Viro restore_nameidata(); 24105c31b6ceSAl Viro return name; 24118bcb77faSAl Viro } 24128bcb77faSAl Viro 241379714f72SAl Viro /* does lookup, returns the object with parent locked */ 241479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24155590ff0dSUlrich Drepper { 24165c31b6ceSAl Viro struct filename *filename; 24175c31b6ceSAl Viro struct dentry *d; 2418391172c4SAl Viro struct qstr last; 2419391172c4SAl Viro int type; 242051689104SPaul Moore 24215c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24225c31b6ceSAl Viro &last, &type); 242351689104SPaul Moore if (IS_ERR(filename)) 242451689104SPaul Moore return ERR_CAST(filename); 24255c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2426391172c4SAl Viro path_put(path); 24275c31b6ceSAl Viro putname(filename); 24285c31b6ceSAl Viro return ERR_PTR(-EINVAL); 242979714f72SAl Viro } 24305955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2431391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 243279714f72SAl Viro if (IS_ERR(d)) { 24335955102cSAl Viro inode_unlock(path->dentry->d_inode); 2434391172c4SAl Viro path_put(path); 243579714f72SAl Viro } 243651689104SPaul Moore putname(filename); 243779714f72SAl Viro return d; 24385590ff0dSUlrich Drepper } 24395590ff0dSUlrich Drepper 2440d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2441d1811465SAl Viro { 2442abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2443abc9f5beSAl Viro flags, path, NULL); 2444d1811465SAl Viro } 24454d359507SAl Viro EXPORT_SYMBOL(kern_path); 2446d1811465SAl Viro 244716f18200SJosef 'Jeff' Sipek /** 244816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 244916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 245016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 245116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 245216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2453e0a01249SAl Viro * @path: pointer to struct path to fill 245416f18200SJosef 'Jeff' Sipek */ 245516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 245616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2457e0a01249SAl Viro struct path *path) 245816f18200SJosef 'Jeff' Sipek { 24599ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24609ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2461abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2462abc9f5beSAl Viro flags , path, &root); 246316f18200SJosef 'Jeff' Sipek } 24644d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 246516f18200SJosef 'Jeff' Sipek 24663c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24673c95f0dcSAl Viro int len, struct qstr *this) 24683c95f0dcSAl Viro { 24693c95f0dcSAl Viro this->name = name; 24703c95f0dcSAl Viro this->len = len; 24713c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24723c95f0dcSAl Viro if (!len) 24733c95f0dcSAl Viro return -EACCES; 24743c95f0dcSAl Viro 24753c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24763c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24773c95f0dcSAl Viro return -EACCES; 24783c95f0dcSAl Viro } 24793c95f0dcSAl Viro 24803c95f0dcSAl Viro while (len--) { 24813c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24823c95f0dcSAl Viro if (c == '/' || c == '\0') 24833c95f0dcSAl Viro return -EACCES; 24843c95f0dcSAl Viro } 24853c95f0dcSAl Viro /* 24863c95f0dcSAl Viro * See if the low-level filesystem might want 24873c95f0dcSAl Viro * to use its own hash.. 24883c95f0dcSAl Viro */ 24893c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24903c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24913c95f0dcSAl Viro if (err < 0) 24923c95f0dcSAl Viro return err; 24933c95f0dcSAl Viro } 24943c95f0dcSAl Viro 24953c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24963c95f0dcSAl Viro } 24973c95f0dcSAl Viro 2498eead1911SChristoph Hellwig /** 24990da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25000da0b7fdSDavid Howells * @name: pathname component to lookup 25010da0b7fdSDavid Howells * @base: base directory to lookup from 25020da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25030da0b7fdSDavid Howells * 25040da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25050da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25060da0b7fdSDavid Howells * 25070da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25080da0b7fdSDavid Howells * not be called by generic code. 25090da0b7fdSDavid Howells * 25100da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25110da0b7fdSDavid Howells */ 25120da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25130da0b7fdSDavid Howells { 25140da0b7fdSDavid Howells struct qstr this; 25150da0b7fdSDavid Howells int err; 25160da0b7fdSDavid Howells 25170da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25180da0b7fdSDavid Howells 25190da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25200da0b7fdSDavid Howells if (err) 25210da0b7fdSDavid Howells return ERR_PTR(err); 25220da0b7fdSDavid Howells 25230da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25240da0b7fdSDavid Howells } 25250da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25260da0b7fdSDavid Howells 25270da0b7fdSDavid Howells /** 2528a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2529eead1911SChristoph Hellwig * @name: pathname component to lookup 2530eead1911SChristoph Hellwig * @base: base directory to lookup from 2531eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2532eead1911SChristoph Hellwig * 2533a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25349e7543e9SAl Viro * not be called by generic code. 2535bbddca8eSNeilBrown * 2536bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2537eead1911SChristoph Hellwig */ 2538057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2539057f6c01SJames Morris { 25408613a209SAl Viro struct dentry *dentry; 2541057f6c01SJames Morris struct qstr this; 2542cda309deSMiklos Szeredi int err; 2543057f6c01SJames Morris 25445955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25452f9092e1SDavid Woodhouse 25463c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2547cda309deSMiklos Szeredi if (err) 2548cda309deSMiklos Szeredi return ERR_PTR(err); 2549cda309deSMiklos Szeredi 25508613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25518613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2552057f6c01SJames Morris } 25534d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2554057f6c01SJames Morris 2555bbddca8eSNeilBrown /** 2556bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2557bbddca8eSNeilBrown * @name: pathname component to lookup 2558bbddca8eSNeilBrown * @base: base directory to lookup from 2559bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2560bbddca8eSNeilBrown * 2561bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2562bbddca8eSNeilBrown * not be called by generic code. 2563bbddca8eSNeilBrown * 2564bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2565bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2566bbddca8eSNeilBrown */ 2567bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2568bbddca8eSNeilBrown struct dentry *base, int len) 2569bbddca8eSNeilBrown { 2570bbddca8eSNeilBrown struct qstr this; 2571bbddca8eSNeilBrown int err; 257220d00ee8SLinus Torvalds struct dentry *ret; 2573bbddca8eSNeilBrown 25743c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2575bbddca8eSNeilBrown if (err) 2576bbddca8eSNeilBrown return ERR_PTR(err); 2577bbddca8eSNeilBrown 257820d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 257920d00ee8SLinus Torvalds if (!ret) 258020d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 258120d00ee8SLinus Torvalds return ret; 2582bbddca8eSNeilBrown } 2583bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2584bbddca8eSNeilBrown 25856c2d4798SAl Viro /* 25866c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 25876c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 25886c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 25896c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 25906c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 25916c2d4798SAl Viro * this one avoids such problems. 25926c2d4798SAl Viro */ 25936c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 25946c2d4798SAl Viro struct dentry *base, int len) 25956c2d4798SAl Viro { 25966c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 25972fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 25986c2d4798SAl Viro dput(ret); 25996c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26006c2d4798SAl Viro } 26016c2d4798SAl Viro return ret; 26026c2d4798SAl Viro } 26036c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26046c2d4798SAl Viro 2605eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2606eedf265aSEric W. Biederman int path_pts(struct path *path) 2607eedf265aSEric W. Biederman { 2608eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2609eedf265aSEric W. Biederman * the input path. 2610eedf265aSEric W. Biederman */ 2611a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2612a6a7eb76SAl Viro struct dentry *child; 2613eedf265aSEric W. Biederman struct qstr this; 2614eedf265aSEric W. Biederman 2615a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2616a6a7eb76SAl Viro dput(parent); 261763b27720SAl Viro return -ENOENT; 2618a6a7eb76SAl Viro } 261963b27720SAl Viro dput(path->dentry); 262063b27720SAl Viro path->dentry = parent; 2621eedf265aSEric W. Biederman this.name = "pts"; 2622eedf265aSEric W. Biederman this.len = 3; 2623eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2624eedf265aSEric W. Biederman if (!child) 2625eedf265aSEric W. Biederman return -ENOENT; 2626eedf265aSEric W. Biederman 2627eedf265aSEric W. Biederman path->dentry = child; 2628eedf265aSEric W. Biederman dput(parent); 2629eedf265aSEric W. Biederman follow_mount(path); 2630eedf265aSEric W. Biederman return 0; 2631eedf265aSEric W. Biederman } 2632eedf265aSEric W. Biederman #endif 2633eedf265aSEric W. Biederman 26341fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26351fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26361da177e4SLinus Torvalds { 2637abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2638abc9f5beSAl Viro flags, path, NULL); 26391da177e4SLinus Torvalds } 2640b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26411fa1e7f6SAndy Whitcroft 2642cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26431da177e4SLinus Torvalds { 26448e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2645da9592edSDavid Howells 26468e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26471da177e4SLinus Torvalds return 0; 26488e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26491da177e4SLinus Torvalds return 0; 265023adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26511da177e4SLinus Torvalds } 2652cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26531da177e4SLinus Torvalds 26541da177e4SLinus Torvalds /* 26551da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26561da177e4SLinus Torvalds * whether the type of victim is right. 26571da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26581da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26591da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26601da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26611da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26621da177e4SLinus Torvalds * a. be owner of dir, or 26631da177e4SLinus Torvalds * b. be owner of victim, or 26641da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26651da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26661da177e4SLinus Torvalds * links pointing to it. 26670bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26680bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26690bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26700bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 26710bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 26721da177e4SLinus Torvalds * nfs_async_unlink(). 26731da177e4SLinus Torvalds */ 2674b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26751da177e4SLinus Torvalds { 267663afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26771da177e4SLinus Torvalds int error; 26781da177e4SLinus Torvalds 2679b18825a7SDavid Howells if (d_is_negative(victim)) 26801da177e4SLinus Torvalds return -ENOENT; 2681b18825a7SDavid Howells BUG_ON(!inode); 26821da177e4SLinus Torvalds 26831da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2684593d1ce8SEric W. Biederman 2685593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2686593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2687593d1ce8SEric W. Biederman return -EOVERFLOW; 2688593d1ce8SEric W. Biederman 26894fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 26901da177e4SLinus Torvalds 2691f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 26921da177e4SLinus Torvalds if (error) 26931da177e4SLinus Torvalds return error; 26941da177e4SLinus Torvalds if (IS_APPEND(dir)) 26951da177e4SLinus Torvalds return -EPERM; 2696b18825a7SDavid Howells 2697b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 26980bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 26991da177e4SLinus Torvalds return -EPERM; 27001da177e4SLinus Torvalds if (isdir) { 270144b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27021da177e4SLinus Torvalds return -ENOTDIR; 27031da177e4SLinus Torvalds if (IS_ROOT(victim)) 27041da177e4SLinus Torvalds return -EBUSY; 270544b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27061da177e4SLinus Torvalds return -EISDIR; 27071da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27081da177e4SLinus Torvalds return -ENOENT; 27091da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27101da177e4SLinus Torvalds return -EBUSY; 27111da177e4SLinus Torvalds return 0; 27121da177e4SLinus Torvalds } 27131da177e4SLinus Torvalds 27141da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27151da177e4SLinus Torvalds * dir. 27161da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27171da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27181da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2719036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2720036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2721036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27221da177e4SLinus Torvalds */ 2723a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27241da177e4SLinus Torvalds { 2725036d5236SEric W. Biederman struct user_namespace *s_user_ns; 272614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27271da177e4SLinus Torvalds if (child->d_inode) 27281da177e4SLinus Torvalds return -EEXIST; 27291da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27301da177e4SLinus Torvalds return -ENOENT; 2731036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2732036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2733036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2734036d5236SEric W. Biederman return -EOVERFLOW; 2735f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27361da177e4SLinus Torvalds } 27371da177e4SLinus Torvalds 27381da177e4SLinus Torvalds /* 27391da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27401da177e4SLinus Torvalds */ 27411da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27421da177e4SLinus Torvalds { 27431da177e4SLinus Torvalds struct dentry *p; 27441da177e4SLinus Torvalds 27451da177e4SLinus Torvalds if (p1 == p2) { 27465955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27471da177e4SLinus Torvalds return NULL; 27481da177e4SLinus Torvalds } 27491da177e4SLinus Torvalds 2750fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27511da177e4SLinus Torvalds 2752e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2753e2761a11SOGAWA Hirofumi if (p) { 27545955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27555955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27561da177e4SLinus Torvalds return p; 27571da177e4SLinus Torvalds } 27581da177e4SLinus Torvalds 2759e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2760e2761a11SOGAWA Hirofumi if (p) { 27615955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27625955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27631da177e4SLinus Torvalds return p; 27641da177e4SLinus Torvalds } 27651da177e4SLinus Torvalds 27665955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27675955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27681da177e4SLinus Torvalds return NULL; 27691da177e4SLinus Torvalds } 27704d359507SAl Viro EXPORT_SYMBOL(lock_rename); 27711da177e4SLinus Torvalds 27721da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 27731da177e4SLinus Torvalds { 27745955102cSAl Viro inode_unlock(p1->d_inode); 27751da177e4SLinus Torvalds if (p1 != p2) { 27765955102cSAl Viro inode_unlock(p2->d_inode); 2777fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 27781da177e4SLinus Torvalds } 27791da177e4SLinus Torvalds } 27804d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 27811da177e4SLinus Torvalds 27824acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2783312b63fbSAl Viro bool want_excl) 27841da177e4SLinus Torvalds { 2785a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27861da177e4SLinus Torvalds if (error) 27871da177e4SLinus Torvalds return error; 27881da177e4SLinus Torvalds 2789acfa4380SAl Viro if (!dir->i_op->create) 27901da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 27911da177e4SLinus Torvalds mode &= S_IALLUGO; 27921da177e4SLinus Torvalds mode |= S_IFREG; 27931da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 27941da177e4SLinus Torvalds if (error) 27951da177e4SLinus Torvalds return error; 2796312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2797a74574aaSStephen Smalley if (!error) 2798f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27991da177e4SLinus Torvalds return error; 28001da177e4SLinus Torvalds } 28014d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28021da177e4SLinus Torvalds 28038e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28048e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28058e6c848eSAl Viro void *arg) 28068e6c848eSAl Viro { 28078e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28088e6c848eSAl Viro int error = may_create(dir, dentry); 28098e6c848eSAl Viro if (error) 28108e6c848eSAl Viro return error; 28118e6c848eSAl Viro 28128e6c848eSAl Viro mode &= S_IALLUGO; 28138e6c848eSAl Viro mode |= S_IFREG; 28148e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28158e6c848eSAl Viro if (error) 28168e6c848eSAl Viro return error; 28178e6c848eSAl Viro error = f(dentry, mode, arg); 28188e6c848eSAl Viro if (!error) 28198e6c848eSAl Viro fsnotify_create(dir, dentry); 28208e6c848eSAl Viro return error; 28218e6c848eSAl Viro } 28228e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28238e6c848eSAl Viro 2824a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2825a2982cc9SEric W. Biederman { 2826a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2827a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2828a2982cc9SEric W. Biederman } 2829a2982cc9SEric W. Biederman 2830f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28311da177e4SLinus Torvalds { 28323fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28331da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28341da177e4SLinus Torvalds int error; 28351da177e4SLinus Torvalds 28361da177e4SLinus Torvalds if (!inode) 28371da177e4SLinus Torvalds return -ENOENT; 28381da177e4SLinus Torvalds 2839c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2840c8fe8f30SChristoph Hellwig case S_IFLNK: 28411da177e4SLinus Torvalds return -ELOOP; 2842c8fe8f30SChristoph Hellwig case S_IFDIR: 2843c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28441da177e4SLinus Torvalds return -EISDIR; 2845c8fe8f30SChristoph Hellwig break; 2846c8fe8f30SChristoph Hellwig case S_IFBLK: 2847c8fe8f30SChristoph Hellwig case S_IFCHR: 2848a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28491da177e4SLinus Torvalds return -EACCES; 2850c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2851c8fe8f30SChristoph Hellwig case S_IFIFO: 2852c8fe8f30SChristoph Hellwig case S_IFSOCK: 28531da177e4SLinus Torvalds flag &= ~O_TRUNC; 2854c8fe8f30SChristoph Hellwig break; 28554a3fd211SDave Hansen } 2856b41572e9SDave Hansen 285762fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2858b41572e9SDave Hansen if (error) 2859b41572e9SDave Hansen return error; 28606146f0d5SMimi Zohar 28611da177e4SLinus Torvalds /* 28621da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28631da177e4SLinus Torvalds */ 28641da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28658737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28667715b521SAl Viro return -EPERM; 28671da177e4SLinus Torvalds if (flag & O_TRUNC) 28687715b521SAl Viro return -EPERM; 28691da177e4SLinus Torvalds } 28701da177e4SLinus Torvalds 28711da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28722e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28737715b521SAl Viro return -EPERM; 28741da177e4SLinus Torvalds 2875f3c7691eSJ. Bruce Fields return 0; 28767715b521SAl Viro } 28777715b521SAl Viro 2878e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28797715b521SAl Viro { 2880f0bb5aafSAl Viro const struct path *path = &filp->f_path; 28817715b521SAl Viro struct inode *inode = path->dentry->d_inode; 28827715b521SAl Viro int error = get_write_access(inode); 28831da177e4SLinus Torvalds if (error) 28847715b521SAl Viro return error; 28851da177e4SLinus Torvalds /* 28861da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 28871da177e4SLinus Torvalds */ 2888d7a06983SJeff Layton error = locks_verify_locked(filp); 2889be6d3e56SKentaro Takeda if (!error) 2890ea0d3ab2STetsuo Handa error = security_path_truncate(path); 28911da177e4SLinus Torvalds if (!error) { 28927715b521SAl Viro error = do_truncate(path->dentry, 0, 2893d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2894e1181ee6SJeff Layton filp); 28951da177e4SLinus Torvalds } 28961da177e4SLinus Torvalds put_write_access(inode); 2897acd0c935SMimi Zohar return error; 28981da177e4SLinus Torvalds } 28991da177e4SLinus Torvalds 2900d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2901d57999e1SDave Hansen { 29028a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29038a5e929dSAl Viro flag--; 2904d57999e1SDave Hansen return flag; 2905d57999e1SDave Hansen } 2906d57999e1SDave Hansen 2907d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2908d18e9008SMiklos Szeredi { 29091328c727SSeth Forshee struct user_namespace *s_user_ns; 2910d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2911d18e9008SMiklos Szeredi if (error) 2912d18e9008SMiklos Szeredi return error; 2913d18e9008SMiklos Szeredi 29141328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29151328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29161328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29171328c727SSeth Forshee return -EOVERFLOW; 29181328c727SSeth Forshee 2919d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2920d18e9008SMiklos Szeredi if (error) 2921d18e9008SMiklos Szeredi return error; 2922d18e9008SMiklos Szeredi 2923d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2924d18e9008SMiklos Szeredi } 2925d18e9008SMiklos Szeredi 29261acf0af9SDavid Howells /* 29271acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29281acf0af9SDavid Howells * dentry. 29291acf0af9SDavid Howells * 29301acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29311acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29321acf0af9SDavid Howells * 293300a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 293400a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 293500a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29361acf0af9SDavid Howells * 29371acf0af9SDavid Howells * Returns an error code otherwise. 29381acf0af9SDavid Howells */ 2939239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2940239eb983SAl Viro struct file *file, 2941015c3bbcSMiklos Szeredi const struct open_flags *op, 29423ec2eef1SAl Viro int open_flag, umode_t mode) 2943d18e9008SMiklos Szeredi { 2944d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2945d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2946d18e9008SMiklos Szeredi int error; 2947d18e9008SMiklos Szeredi 2948384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2949d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2950d18e9008SMiklos Szeredi 2951d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2952d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2953d18e9008SMiklos Szeredi 295430d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 295530d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29560fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 295744907d79SAl Viro open_to_namei_flags(open_flag), mode); 29586fbd0714SAl Viro d_lookup_done(dentry); 2959384f26e2SAl Viro if (!error) { 296064e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 29616fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 29626fb968cdSAl Viro dput(dentry); 29636fb968cdSAl Viro dentry = dget(file->f_path.dentry); 29646fb968cdSAl Viro } 29657be219b4SAl Viro if (file->f_mode & FMODE_CREATED) 296603da633aSAl Viro fsnotify_create(dir, dentry); 296764e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2968116cc022SMiklos Szeredi error = -EIO; 2969384f26e2SAl Viro } else { 2970d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2971d18e9008SMiklos Szeredi dput(dentry); 2972d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 297310c64ceaSAl Viro } 297473a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 2975d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2976239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 2977a01e718fSAl Viro error = -ENOENT; 2978d18e9008SMiklos Szeredi } 2979d18e9008SMiklos Szeredi } 2980239eb983SAl Viro if (error) { 2981d18e9008SMiklos Szeredi dput(dentry); 2982239eb983SAl Viro dentry = ERR_PTR(error); 2983239eb983SAl Viro } 2984239eb983SAl Viro return dentry; 2985d18e9008SMiklos Szeredi } 2986d18e9008SMiklos Szeredi 298731e6b01fSNick Piggin /* 29881acf0af9SDavid Howells * Look up and maybe create and open the last component. 2989d58ffd35SMiklos Szeredi * 299000a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 2991d58ffd35SMiklos Szeredi * 299200a07c15SAl Viro * Returns 0 on success, that is, if 299300a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 299400a07c15SAl Viro * the file was not completely opened at this time, though lookups and 299500a07c15SAl Viro * creations were performed. 299600a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 299700a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 299800a07c15SAl Viro * hadn't been specified. 29991acf0af9SDavid Howells * 300000a07c15SAl Viro * An error code is returned on failure. 3001d58ffd35SMiklos Szeredi */ 3002da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3003d58ffd35SMiklos Szeredi const struct open_flags *op, 30043ec2eef1SAl Viro bool got_write) 3005d58ffd35SMiklos Szeredi { 3006d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 300754ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30081643b43fSAl Viro int open_flag = op->open_flag; 3009d58ffd35SMiklos Szeredi struct dentry *dentry; 30101643b43fSAl Viro int error, create_error = 0; 30111643b43fSAl Viro umode_t mode = op->mode; 30126fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3013d58ffd35SMiklos Szeredi 3014ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3015da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3016d58ffd35SMiklos Szeredi 301773a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30186fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30196fbd0714SAl Viro for (;;) { 30206fbd0714SAl Viro if (!dentry) { 30216fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3022d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3023da5ebf5aSAl Viro return dentry; 30246fbd0714SAl Viro } 30256fbd0714SAl Viro if (d_in_lookup(dentry)) 30266fbd0714SAl Viro break; 3027d58ffd35SMiklos Szeredi 30286fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30296fbd0714SAl Viro if (likely(error > 0)) 30306fbd0714SAl Viro break; 30316fbd0714SAl Viro if (error) 30326fbd0714SAl Viro goto out_dput; 30336fbd0714SAl Viro d_invalidate(dentry); 30346fbd0714SAl Viro dput(dentry); 30356fbd0714SAl Viro dentry = NULL; 30366fbd0714SAl Viro } 30376fbd0714SAl Viro if (dentry->d_inode) { 3038d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3039da5ebf5aSAl Viro return dentry; 30406c51e513SAl Viro } 3041d18e9008SMiklos Szeredi 30421643b43fSAl Viro /* 30431643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30441643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30451643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30461643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30471643b43fSAl Viro * 30481643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30491643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30501643b43fSAl Viro */ 30511643b43fSAl Viro if (open_flag & O_CREAT) { 30521643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30531643b43fSAl Viro mode &= ~current_umask(); 30541643b43fSAl Viro if (unlikely(!got_write)) { 30551643b43fSAl Viro create_error = -EROFS; 30561643b43fSAl Viro open_flag &= ~O_CREAT; 30571643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30581643b43fSAl Viro goto no_open; 30591643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30601643b43fSAl Viro } else { 30611643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30621643b43fSAl Viro if (create_error) { 30631643b43fSAl Viro open_flag &= ~O_CREAT; 30641643b43fSAl Viro if (open_flag & O_EXCL) 30651643b43fSAl Viro goto no_open; 30661643b43fSAl Viro } 30671643b43fSAl Viro } 30681643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30691643b43fSAl Viro unlikely(!got_write)) { 30701643b43fSAl Viro /* 30711643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30721643b43fSAl Viro * back to lookup + open 30731643b43fSAl Viro */ 30741643b43fSAl Viro goto no_open; 3075d18e9008SMiklos Szeredi } 3076d18e9008SMiklos Szeredi 30771643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3078239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3079da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3080da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3081da5ebf5aSAl Viro return dentry; 3082239eb983SAl Viro } 308354ef4872SMiklos Szeredi 30841643b43fSAl Viro no_open: 30856fbd0714SAl Viro if (d_in_lookup(dentry)) { 308612fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 308712fa5e24SAl Viro nd->flags); 30886fbd0714SAl Viro d_lookup_done(dentry); 308912fa5e24SAl Viro if (unlikely(res)) { 309012fa5e24SAl Viro if (IS_ERR(res)) { 309112fa5e24SAl Viro error = PTR_ERR(res); 309212fa5e24SAl Viro goto out_dput; 309312fa5e24SAl Viro } 309412fa5e24SAl Viro dput(dentry); 309512fa5e24SAl Viro dentry = res; 309612fa5e24SAl Viro } 309754ef4872SMiklos Szeredi } 309854ef4872SMiklos Szeredi 3099d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31001643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 310173a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3102ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3103ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3104ce8644fcSAl Viro error = -EACCES; 3105d58ffd35SMiklos Szeredi goto out_dput; 310664894cf8SAl Viro } 3107ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31081643b43fSAl Viro open_flag & O_EXCL); 3109d58ffd35SMiklos Szeredi if (error) 3110d58ffd35SMiklos Szeredi goto out_dput; 3111ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3112d58ffd35SMiklos Szeredi } 31131643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31141643b43fSAl Viro error = create_error; 3115d58ffd35SMiklos Szeredi goto out_dput; 3116d58ffd35SMiklos Szeredi } 3117da5ebf5aSAl Viro return dentry; 3118d58ffd35SMiklos Szeredi 3119d58ffd35SMiklos Szeredi out_dput: 3120d58ffd35SMiklos Szeredi dput(dentry); 3121da5ebf5aSAl Viro return ERR_PTR(error); 3122d58ffd35SMiklos Szeredi } 3123d58ffd35SMiklos Szeredi 3124c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 31253ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3126fb1cc555SAl Viro { 3127a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3128ca344a89SAl Viro int open_flag = op->open_flag; 312964894cf8SAl Viro bool got_write = false; 3130254cf582SAl Viro unsigned seq; 3131a1eb3315SMiklos Szeredi struct inode *inode; 3132da5ebf5aSAl Viro struct dentry *dentry; 3133b0417d2cSAl Viro const char *res; 313416c2cd71SAl Viro int error; 3135fb1cc555SAl Viro 3136c3e380b0SAl Viro nd->flags |= op->intent; 3137c3e380b0SAl Viro 3138bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 313956676ec3SAl Viro if (nd->depth) 314056676ec3SAl Viro put_link(nd); 31417521f22bSAl Viro res = handle_dots(nd, nd->last_type); 31427521f22bSAl Viro if (likely(!res)) 31437521f22bSAl Viro res = ERR_PTR(complete_walk(nd)); 31447521f22bSAl Viro return res; 31451f36f774SAl Viro } 3146a2c36b45SAl Viro 3147ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3148fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3149fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3150fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 315120e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 315220e34357SAl Viro if (IS_ERR(dentry)) 31531ccac622SAl Viro return ERR_CAST(dentry); 315420e34357SAl Viro if (likely(dentry)) 315571574865SMiklos Szeredi goto finish_lookup; 315671574865SMiklos Szeredi 31576583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3158b6183df7SMiklos Szeredi } else { 3159fe2d35ffSAl Viro /* create side of things */ 3160a3fbbde7SAl Viro /* 3161b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3162b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3163b6183df7SMiklos Szeredi * about to look up 3164a3fbbde7SAl Viro */ 31659f1fafeeSAl Viro error = complete_walk(nd); 3166c981a482SAl Viro if (unlikely(error)) 31671ccac622SAl Viro return ERR_PTR(error); 3168fe2d35ffSAl Viro 3169c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 31701f36f774SAl Viro /* trailing slashes? */ 3171deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 31721ccac622SAl Viro return ERR_PTR(-EISDIR); 3173b6183df7SMiklos Szeredi } 31741f36f774SAl Viro 31759cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 317664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 317764894cf8SAl Viro if (!error) 317864894cf8SAl Viro got_write = true; 317964894cf8SAl Viro /* 318064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 318164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 318264894cf8SAl Viro * dropping this one anyway. 318364894cf8SAl Viro */ 318464894cf8SAl Viro } 31859cf843e3SAl Viro if (open_flag & O_CREAT) 31865955102cSAl Viro inode_lock(dir->d_inode); 31879cf843e3SAl Viro else 31889cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3189da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 31909cf843e3SAl Viro if (open_flag & O_CREAT) 31915955102cSAl Viro inode_unlock(dir->d_inode); 31929cf843e3SAl Viro else 31939cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3194fb1cc555SAl Viro 3195c981a482SAl Viro if (got_write) 319659e96e65SAl Viro mnt_drop_write(nd->path.mnt); 31976c0d46c4SAl Viro 319859e96e65SAl Viro if (IS_ERR(dentry)) 319959e96e65SAl Viro return ERR_CAST(dentry); 320059e96e65SAl Viro 3201973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3202e73cabffSAl Viro dput(nd->path.dentry); 3203e73cabffSAl Viro nd->path.dentry = dentry; 3204c981a482SAl Viro return NULL; 3205fb1cc555SAl Viro } 3206fb1cc555SAl Viro 320720e34357SAl Viro finish_lookup: 320856676ec3SAl Viro if (nd->depth) 320956676ec3SAl Viro put_link(nd); 32108c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3211b0417d2cSAl Viro if (unlikely(res)) { 32121ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3213b0417d2cSAl Viro return res; 32141ccac622SAl Viro } 321531d1726dSAl Viro 321631d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 321731d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32181ccac622SAl Viro return ERR_PTR(-EEXIST); 321931d1726dSAl Viro } 3220c981a482SAl Viro 32218f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3222c981a482SAl Viro return ERR_PTR(complete_walk(nd)); 3223c981a482SAl Viro } 3224c981a482SAl Viro 3225c981a482SAl Viro /* 3226c981a482SAl Viro * Handle the last step of open() 3227c981a482SAl Viro */ 3228c981a482SAl Viro static const char *do_last(struct nameidata *nd, 3229c981a482SAl Viro struct file *file, const struct open_flags *op) 3230c981a482SAl Viro { 3231c981a482SAl Viro kuid_t dir_uid = nd->inode->i_uid; 3232c981a482SAl Viro umode_t dir_mode = nd->inode->i_mode; 3233c981a482SAl Viro int open_flag = op->open_flag; 3234c981a482SAl Viro bool do_truncate; 3235c981a482SAl Viro int acc_mode; 3236c981a482SAl Viro const char *link; 3237c981a482SAl Viro int error; 3238c981a482SAl Viro 3239c981a482SAl Viro link = open_last_lookups(nd, file, op); 3240c981a482SAl Viro if (unlikely(link)) 3241c981a482SAl Viro return link; 3242c981a482SAl Viro 3243973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 324476ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 324530aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 324630aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 324759e96e65SAl Viro return ERR_PTR(-EISDIR); 3248d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 324930aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 325030aba665SSalvatore Mesoraca if (unlikely(error)) 325159e96e65SAl Viro return ERR_PTR(error); 325230aba665SSalvatore Mesoraca } 325344b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 325459e96e65SAl Viro return ERR_PTR(-ENOTDIR); 32556c0d46c4SAl Viro 32568795e7d4SAl Viro do_truncate = false; 32578795e7d4SAl Viro acc_mode = op->acc_mode; 32585a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32595a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32605a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32615a2d3eddSAl Viro acc_mode = 0; 32628795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32630f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32640f9d1a10SAl Viro if (error) 326559e96e65SAl Viro return ERR_PTR(error); 32668795e7d4SAl Viro do_truncate = true; 32670f9d1a10SAl Viro } 3268bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 32698795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3270ae2bb293SAl Viro error = vfs_open(&nd->path, file); 32718795e7d4SAl Viro if (!error) 32726035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 32738795e7d4SAl Viro if (!error && do_truncate) 32742675a4ebSAl Viro error = handle_truncate(file); 3275c80567c8SAl Viro if (unlikely(error > 0)) { 3276c80567c8SAl Viro WARN_ON(1); 3277c80567c8SAl Viro error = -EINVAL; 3278c80567c8SAl Viro } 32798795e7d4SAl Viro if (do_truncate) 32800f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 32811ccac622SAl Viro return ERR_PTR(error); 3282fb1cc555SAl Viro } 3283fb1cc555SAl Viro 3284af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3285af7bd4dcSAmir Goldstein { 3286af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3287af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3288af7bd4dcSAmir Goldstein struct inode *inode; 3289af7bd4dcSAmir Goldstein int error; 3290af7bd4dcSAmir Goldstein 3291af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3292af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3293af7bd4dcSAmir Goldstein if (error) 3294af7bd4dcSAmir Goldstein goto out_err; 3295af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3296af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3297af7bd4dcSAmir Goldstein goto out_err; 3298af7bd4dcSAmir Goldstein error = -ENOMEM; 3299cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3300af7bd4dcSAmir Goldstein if (unlikely(!child)) 3301af7bd4dcSAmir Goldstein goto out_err; 3302af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3303af7bd4dcSAmir Goldstein if (error) 3304af7bd4dcSAmir Goldstein goto out_err; 3305af7bd4dcSAmir Goldstein error = -ENOENT; 3306af7bd4dcSAmir Goldstein inode = child->d_inode; 3307af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3308af7bd4dcSAmir Goldstein goto out_err; 3309af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3310af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3311af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3312af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3313af7bd4dcSAmir Goldstein } 3314fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3315af7bd4dcSAmir Goldstein return child; 3316af7bd4dcSAmir Goldstein 3317af7bd4dcSAmir Goldstein out_err: 3318af7bd4dcSAmir Goldstein dput(child); 3319af7bd4dcSAmir Goldstein return ERR_PTR(error); 3320af7bd4dcSAmir Goldstein } 3321af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3322af7bd4dcSAmir Goldstein 3323c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 332460545d0dSAl Viro const struct open_flags *op, 33253ec2eef1SAl Viro struct file *file) 332660545d0dSAl Viro { 3327625b6d10SAl Viro struct dentry *child; 3328625b6d10SAl Viro struct path path; 3329c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 333060545d0dSAl Viro if (unlikely(error)) 333160545d0dSAl Viro return error; 3332625b6d10SAl Viro error = mnt_want_write(path.mnt); 333360545d0dSAl Viro if (unlikely(error)) 333460545d0dSAl Viro goto out; 3335af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3336af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3337684e73beSHirofumi Nakagawa if (IS_ERR(child)) 333860545d0dSAl Viro goto out2; 3339625b6d10SAl Viro dput(path.dentry); 3340625b6d10SAl Viro path.dentry = child; 3341c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 334269a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 334362fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 334460545d0dSAl Viro if (error) 334560545d0dSAl Viro goto out2; 3346625b6d10SAl Viro file->f_path.mnt = path.mnt; 3347be12af3eSAl Viro error = finish_open(file, child, NULL); 334860545d0dSAl Viro out2: 3349625b6d10SAl Viro mnt_drop_write(path.mnt); 335060545d0dSAl Viro out: 3351625b6d10SAl Viro path_put(&path); 335260545d0dSAl Viro return error; 335360545d0dSAl Viro } 335460545d0dSAl Viro 33556ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33566ac08709SAl Viro { 33576ac08709SAl Viro struct path path; 33586ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33596ac08709SAl Viro if (!error) { 33606ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3361ae2bb293SAl Viro error = vfs_open(&path, file); 33626ac08709SAl Viro path_put(&path); 33636ac08709SAl Viro } 33646ac08709SAl Viro return error; 33656ac08709SAl Viro } 33666ac08709SAl Viro 3367c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3368c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33691da177e4SLinus Torvalds { 337030d90494SAl Viro struct file *file; 337113aab428SAl Viro int error; 337231e6b01fSNick Piggin 3373ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 33741afc99beSAl Viro if (IS_ERR(file)) 33751afc99beSAl Viro return file; 337631e6b01fSNick Piggin 3377bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 33783ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 33795f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 33806ac08709SAl Viro error = do_o_path(nd, flags, file); 33815f336e72SAl Viro } else { 33825f336e72SAl Viro const char *s = path_init(nd, flags); 33833bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33841ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 33851ccac622SAl Viro ; 3386deb106c6SAl Viro terminate_walk(nd); 33875f336e72SAl Viro } 33887c1c01ecSAl Viro if (likely(!error)) { 3389aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 33907c1c01ecSAl Viro return file; 33917c1c01ecSAl Viro WARN_ON(1); 33927c1c01ecSAl Viro error = -EINVAL; 3393015c3bbcSMiklos Szeredi } 33947c1c01ecSAl Viro fput(file); 33952675a4ebSAl Viro if (error == -EOPENSTALE) { 33962675a4ebSAl Viro if (flags & LOOKUP_RCU) 33972675a4ebSAl Viro error = -ECHILD; 33982675a4ebSAl Viro else 33992675a4ebSAl Viro error = -ESTALE; 34002675a4ebSAl Viro } 34017c1c01ecSAl Viro return ERR_PTR(error); 3402de459215SKirill Korotaev } 34031da177e4SLinus Torvalds 3404669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3405f9652e10SAl Viro const struct open_flags *op) 340613aab428SAl Viro { 34079883d185SAl Viro struct nameidata nd; 3408f9652e10SAl Viro int flags = op->lookup_flags; 340913aab428SAl Viro struct file *filp; 341013aab428SAl Viro 34119883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3412c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 341313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3414c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 341513aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3416c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34179883d185SAl Viro restore_nameidata(); 341813aab428SAl Viro return filp; 341913aab428SAl Viro } 342013aab428SAl Viro 342173d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3422f9652e10SAl Viro const char *name, const struct open_flags *op) 342373d049a4SAl Viro { 34249883d185SAl Viro struct nameidata nd; 342573d049a4SAl Viro struct file *file; 342651689104SPaul Moore struct filename *filename; 3427f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 342873d049a4SAl Viro 342973d049a4SAl Viro nd.root.mnt = mnt; 343073d049a4SAl Viro nd.root.dentry = dentry; 343173d049a4SAl Viro 3432b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 343373d049a4SAl Viro return ERR_PTR(-ELOOP); 343473d049a4SAl Viro 343551689104SPaul Moore filename = getname_kernel(name); 3436a1c83681SViresh Kumar if (IS_ERR(filename)) 343751689104SPaul Moore return ERR_CAST(filename); 343851689104SPaul Moore 34399883d185SAl Viro set_nameidata(&nd, -1, filename); 3440c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 344173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3442c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 344373d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3444c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34459883d185SAl Viro restore_nameidata(); 344651689104SPaul Moore putname(filename); 344773d049a4SAl Viro return file; 344873d049a4SAl Viro } 344973d049a4SAl Viro 3450fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34511ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34521da177e4SLinus Torvalds { 3453c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3454391172c4SAl Viro struct qstr last; 3455391172c4SAl Viro int type; 3456c30dabfeSJan Kara int err2; 34571ac12b4bSJeff Layton int error; 34581ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34591ac12b4bSJeff Layton 34601ac12b4bSJeff Layton /* 34611ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34621ac12b4bSJeff Layton * other flags passed in are ignored! 34631ac12b4bSJeff Layton */ 34641ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34651ac12b4bSJeff Layton 34665c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34675c31b6ceSAl Viro if (IS_ERR(name)) 34685c31b6ceSAl Viro return ERR_CAST(name); 34691da177e4SLinus Torvalds 3470c663e5d8SChristoph Hellwig /* 3471c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3472c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3473c663e5d8SChristoph Hellwig */ 34745c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3475ed75e95dSAl Viro goto out; 3476c663e5d8SChristoph Hellwig 3477c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3478391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3479c663e5d8SChristoph Hellwig /* 3480c663e5d8SChristoph Hellwig * Do the final lookup. 3481c663e5d8SChristoph Hellwig */ 3482391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 34835955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3484391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34851da177e4SLinus Torvalds if (IS_ERR(dentry)) 3486a8104a9fSAl Viro goto unlock; 3487c663e5d8SChristoph Hellwig 3488a8104a9fSAl Viro error = -EEXIST; 3489b18825a7SDavid Howells if (d_is_positive(dentry)) 3490a8104a9fSAl Viro goto fail; 3491b18825a7SDavid Howells 3492c663e5d8SChristoph Hellwig /* 3493c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3494c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3495c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3496c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3497c663e5d8SChristoph Hellwig */ 3498391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3499a8104a9fSAl Viro error = -ENOENT; 3500ed75e95dSAl Viro goto fail; 3501e9baf6e5SAl Viro } 3502c30dabfeSJan Kara if (unlikely(err2)) { 3503c30dabfeSJan Kara error = err2; 3504a8104a9fSAl Viro goto fail; 3505c30dabfeSJan Kara } 3506181c37b6SAl Viro putname(name); 3507e9baf6e5SAl Viro return dentry; 35081da177e4SLinus Torvalds fail: 3509a8104a9fSAl Viro dput(dentry); 3510a8104a9fSAl Viro dentry = ERR_PTR(error); 3511a8104a9fSAl Viro unlock: 35125955102cSAl Viro inode_unlock(path->dentry->d_inode); 3513c30dabfeSJan Kara if (!err2) 3514391172c4SAl Viro mnt_drop_write(path->mnt); 3515ed75e95dSAl Viro out: 3516391172c4SAl Viro path_put(path); 3517181c37b6SAl Viro putname(name); 3518ed75e95dSAl Viro return dentry; 3519dae6ad8fSAl Viro } 3520fa14a0b8SAl Viro 3521fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3522fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3523fa14a0b8SAl Viro { 3524181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3525181c37b6SAl Viro path, lookup_flags); 3526fa14a0b8SAl Viro } 3527dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3528dae6ad8fSAl Viro 3529921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3530921a1650SAl Viro { 3531921a1650SAl Viro dput(dentry); 35325955102cSAl Viro inode_unlock(path->dentry->d_inode); 3533a8104a9fSAl Viro mnt_drop_write(path->mnt); 3534921a1650SAl Viro path_put(path); 3535921a1650SAl Viro } 3536921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3537921a1650SAl Viro 3538520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35391ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3540dae6ad8fSAl Viro { 3541181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3542dae6ad8fSAl Viro } 3543dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3544dae6ad8fSAl Viro 35451a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35461da177e4SLinus Torvalds { 3547a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35481da177e4SLinus Torvalds 35491da177e4SLinus Torvalds if (error) 35501da177e4SLinus Torvalds return error; 35511da177e4SLinus Torvalds 355294f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35531da177e4SLinus Torvalds return -EPERM; 35541da177e4SLinus Torvalds 3555acfa4380SAl Viro if (!dir->i_op->mknod) 35561da177e4SLinus Torvalds return -EPERM; 35571da177e4SLinus Torvalds 355808ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 355908ce5f16SSerge E. Hallyn if (error) 356008ce5f16SSerge E. Hallyn return error; 356108ce5f16SSerge E. Hallyn 35621da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35631da177e4SLinus Torvalds if (error) 35641da177e4SLinus Torvalds return error; 35651da177e4SLinus Torvalds 35661da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3567a74574aaSStephen Smalley if (!error) 3568f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35691da177e4SLinus Torvalds return error; 35701da177e4SLinus Torvalds } 35714d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35721da177e4SLinus Torvalds 3573f69aac00SAl Viro static int may_mknod(umode_t mode) 3574463c3197SDave Hansen { 3575463c3197SDave Hansen switch (mode & S_IFMT) { 3576463c3197SDave Hansen case S_IFREG: 3577463c3197SDave Hansen case S_IFCHR: 3578463c3197SDave Hansen case S_IFBLK: 3579463c3197SDave Hansen case S_IFIFO: 3580463c3197SDave Hansen case S_IFSOCK: 3581463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3582463c3197SDave Hansen return 0; 3583463c3197SDave Hansen case S_IFDIR: 3584463c3197SDave Hansen return -EPERM; 3585463c3197SDave Hansen default: 3586463c3197SDave Hansen return -EINVAL; 3587463c3197SDave Hansen } 3588463c3197SDave Hansen } 3589463c3197SDave Hansen 359087c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 359187c4e192SDominik Brodowski unsigned int dev) 35921da177e4SLinus Torvalds { 35931da177e4SLinus Torvalds struct dentry *dentry; 3594dae6ad8fSAl Viro struct path path; 3595dae6ad8fSAl Viro int error; 3596972567f1SJeff Layton unsigned int lookup_flags = 0; 35971da177e4SLinus Torvalds 35988e4bfca1SAl Viro error = may_mknod(mode); 35998e4bfca1SAl Viro if (error) 36008e4bfca1SAl Viro return error; 3601972567f1SJeff Layton retry: 3602972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3603dae6ad8fSAl Viro if (IS_ERR(dentry)) 3604dae6ad8fSAl Viro return PTR_ERR(dentry); 36052ad94ae6SAl Viro 3606dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3607ce3b0f8dSAl Viro mode &= ~current_umask(); 3608dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3609be6d3e56SKentaro Takeda if (error) 3610a8104a9fSAl Viro goto out; 36111da177e4SLinus Torvalds switch (mode & S_IFMT) { 36121da177e4SLinus Torvalds case 0: case S_IFREG: 3613312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 361405d1a717SMimi Zohar if (!error) 361505d1a717SMimi Zohar ima_post_path_mknod(dentry); 36161da177e4SLinus Torvalds break; 36171da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3618dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36191da177e4SLinus Torvalds new_decode_dev(dev)); 36201da177e4SLinus Torvalds break; 36211da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3622dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36231da177e4SLinus Torvalds break; 36241da177e4SLinus Torvalds } 3625a8104a9fSAl Viro out: 3626921a1650SAl Viro done_path_create(&path, dentry); 3627972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3628972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3629972567f1SJeff Layton goto retry; 3630972567f1SJeff Layton } 36311da177e4SLinus Torvalds return error; 36321da177e4SLinus Torvalds } 36331da177e4SLinus Torvalds 363487c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 363587c4e192SDominik Brodowski unsigned int, dev) 363687c4e192SDominik Brodowski { 363787c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 363887c4e192SDominik Brodowski } 363987c4e192SDominik Brodowski 36408208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36415590ff0dSUlrich Drepper { 364287c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36435590ff0dSUlrich Drepper } 36445590ff0dSUlrich Drepper 364518bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36461da177e4SLinus Torvalds { 3647a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36488de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36491da177e4SLinus Torvalds 36501da177e4SLinus Torvalds if (error) 36511da177e4SLinus Torvalds return error; 36521da177e4SLinus Torvalds 3653acfa4380SAl Viro if (!dir->i_op->mkdir) 36541da177e4SLinus Torvalds return -EPERM; 36551da177e4SLinus Torvalds 36561da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36571da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36581da177e4SLinus Torvalds if (error) 36591da177e4SLinus Torvalds return error; 36601da177e4SLinus Torvalds 36618de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36628de52778SAl Viro return -EMLINK; 36638de52778SAl Viro 36641da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3665a74574aaSStephen Smalley if (!error) 3666f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36671da177e4SLinus Torvalds return error; 36681da177e4SLinus Torvalds } 36694d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36701da177e4SLinus Torvalds 36710101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 36721da177e4SLinus Torvalds { 36736902d925SDave Hansen struct dentry *dentry; 3674dae6ad8fSAl Viro struct path path; 3675dae6ad8fSAl Viro int error; 3676b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36771da177e4SLinus Torvalds 3678b76d8b82SJeff Layton retry: 3679b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36806902d925SDave Hansen if (IS_ERR(dentry)) 3681dae6ad8fSAl Viro return PTR_ERR(dentry); 36826902d925SDave Hansen 3683dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3684ce3b0f8dSAl Viro mode &= ~current_umask(); 3685dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3686a8104a9fSAl Viro if (!error) 3687dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3688921a1650SAl Viro done_path_create(&path, dentry); 3689b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3690b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3691b76d8b82SJeff Layton goto retry; 3692b76d8b82SJeff Layton } 36931da177e4SLinus Torvalds return error; 36941da177e4SLinus Torvalds } 36951da177e4SLinus Torvalds 36960101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36970101db7aSDominik Brodowski { 36980101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 36990101db7aSDominik Brodowski } 37000101db7aSDominik Brodowski 3701a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37025590ff0dSUlrich Drepper { 37030101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37045590ff0dSUlrich Drepper } 37055590ff0dSUlrich Drepper 37061da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37071da177e4SLinus Torvalds { 37081da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37091da177e4SLinus Torvalds 37101da177e4SLinus Torvalds if (error) 37111da177e4SLinus Torvalds return error; 37121da177e4SLinus Torvalds 3713acfa4380SAl Viro if (!dir->i_op->rmdir) 37141da177e4SLinus Torvalds return -EPERM; 37151da177e4SLinus Torvalds 37161d2ef590SAl Viro dget(dentry); 37175955102cSAl Viro inode_lock(dentry->d_inode); 3718912dbc15SSage Weil 37191da177e4SLinus Torvalds error = -EBUSY; 37207af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3721912dbc15SSage Weil goto out; 3722912dbc15SSage Weil 37231da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3724912dbc15SSage Weil if (error) 3725912dbc15SSage Weil goto out; 3726912dbc15SSage Weil 37271da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3728912dbc15SSage Weil if (error) 3729912dbc15SSage Weil goto out; 3730912dbc15SSage Weil 37318767712fSAl Viro shrink_dcache_parent(dentry); 37321da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3733d83c49f3SAl Viro dont_mount(dentry); 37348ed936b5SEric W. Biederman detach_mounts(dentry); 3735116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37361da177e4SLinus Torvalds 3737912dbc15SSage Weil out: 37385955102cSAl Viro inode_unlock(dentry->d_inode); 37391d2ef590SAl Viro dput(dentry); 3740912dbc15SSage Weil if (!error) 3741912dbc15SSage Weil d_delete(dentry); 37421da177e4SLinus Torvalds return error; 37431da177e4SLinus Torvalds } 37444d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37451da177e4SLinus Torvalds 3746f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37471da177e4SLinus Torvalds { 37481da177e4SLinus Torvalds int error = 0; 374991a27b2aSJeff Layton struct filename *name; 37501da177e4SLinus Torvalds struct dentry *dentry; 3751f5beed75SAl Viro struct path path; 3752f5beed75SAl Viro struct qstr last; 3753f5beed75SAl Viro int type; 3754c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3755c6ee9206SJeff Layton retry: 3756c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3757c1d4dd27SAl Viro &path, &last, &type); 375891a27b2aSJeff Layton if (IS_ERR(name)) 375991a27b2aSJeff Layton return PTR_ERR(name); 37601da177e4SLinus Torvalds 3761f5beed75SAl Viro switch (type) { 37621da177e4SLinus Torvalds case LAST_DOTDOT: 37631da177e4SLinus Torvalds error = -ENOTEMPTY; 37641da177e4SLinus Torvalds goto exit1; 37651da177e4SLinus Torvalds case LAST_DOT: 37661da177e4SLinus Torvalds error = -EINVAL; 37671da177e4SLinus Torvalds goto exit1; 37681da177e4SLinus Torvalds case LAST_ROOT: 37691da177e4SLinus Torvalds error = -EBUSY; 37701da177e4SLinus Torvalds goto exit1; 37711da177e4SLinus Torvalds } 37720612d9fbSOGAWA Hirofumi 3773f5beed75SAl Viro error = mnt_want_write(path.mnt); 3774c30dabfeSJan Kara if (error) 3775c30dabfeSJan Kara goto exit1; 37760612d9fbSOGAWA Hirofumi 37775955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3778f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37791da177e4SLinus Torvalds error = PTR_ERR(dentry); 37806902d925SDave Hansen if (IS_ERR(dentry)) 37816902d925SDave Hansen goto exit2; 3782e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3783e6bc45d6STheodore Ts'o error = -ENOENT; 3784e6bc45d6STheodore Ts'o goto exit3; 3785e6bc45d6STheodore Ts'o } 3786f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3787be6d3e56SKentaro Takeda if (error) 3788c30dabfeSJan Kara goto exit3; 3789f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37900622753bSDave Hansen exit3: 37911da177e4SLinus Torvalds dput(dentry); 37926902d925SDave Hansen exit2: 37935955102cSAl Viro inode_unlock(path.dentry->d_inode); 3794f5beed75SAl Viro mnt_drop_write(path.mnt); 37951da177e4SLinus Torvalds exit1: 3796f5beed75SAl Viro path_put(&path); 37971da177e4SLinus Torvalds putname(name); 3798c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3799c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3800c6ee9206SJeff Layton goto retry; 3801c6ee9206SJeff Layton } 38021da177e4SLinus Torvalds return error; 38031da177e4SLinus Torvalds } 38041da177e4SLinus Torvalds 38053cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38065590ff0dSUlrich Drepper { 38075590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38085590ff0dSUlrich Drepper } 38095590ff0dSUlrich Drepper 3810b21996e3SJ. Bruce Fields /** 3811b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3812b21996e3SJ. Bruce Fields * @dir: parent directory 3813b21996e3SJ. Bruce Fields * @dentry: victim 3814b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3815b21996e3SJ. Bruce Fields * 3816b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3817b21996e3SJ. Bruce Fields * 3818b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3819b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3820b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3821b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3822b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3823b21996e3SJ. Bruce Fields * 3824b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3825b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3826b21996e3SJ. Bruce Fields * to be NFS exported. 3827b21996e3SJ. Bruce Fields */ 3828b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38291da177e4SLinus Torvalds { 38309accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38311da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38321da177e4SLinus Torvalds 38331da177e4SLinus Torvalds if (error) 38341da177e4SLinus Torvalds return error; 38351da177e4SLinus Torvalds 3836acfa4380SAl Viro if (!dir->i_op->unlink) 38371da177e4SLinus Torvalds return -EPERM; 38381da177e4SLinus Torvalds 38395955102cSAl Viro inode_lock(target); 38408ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38411da177e4SLinus Torvalds error = -EBUSY; 38421da177e4SLinus Torvalds else { 38431da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3844bec1052eSAl Viro if (!error) { 38455a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38465a14696cSJ. Bruce Fields if (error) 3847b21996e3SJ. Bruce Fields goto out; 38481da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38498ed936b5SEric W. Biederman if (!error) { 3850d83c49f3SAl Viro dont_mount(dentry); 38518ed936b5SEric W. Biederman detach_mounts(dentry); 3852116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38538ed936b5SEric W. Biederman } 3854bec1052eSAl Viro } 38551da177e4SLinus Torvalds } 3856b21996e3SJ. Bruce Fields out: 38575955102cSAl Viro inode_unlock(target); 38581da177e4SLinus Torvalds 38591da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38601da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38619accbb97SJ. Bruce Fields fsnotify_link_count(target); 38621da177e4SLinus Torvalds d_delete(dentry); 38631da177e4SLinus Torvalds } 38640eeca283SRobert Love 38651da177e4SLinus Torvalds return error; 38661da177e4SLinus Torvalds } 38674d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38681da177e4SLinus Torvalds 38691da177e4SLinus Torvalds /* 38701da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38711b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38721da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38731da177e4SLinus Torvalds * while waiting on the I/O. 38741da177e4SLinus Torvalds */ 3875da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 38761da177e4SLinus Torvalds { 38772ad94ae6SAl Viro int error; 38781da177e4SLinus Torvalds struct dentry *dentry; 3879f5beed75SAl Viro struct path path; 3880f5beed75SAl Viro struct qstr last; 3881f5beed75SAl Viro int type; 38821da177e4SLinus Torvalds struct inode *inode = NULL; 3883b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38845d18f813SJeff Layton unsigned int lookup_flags = 0; 38855d18f813SJeff Layton retry: 3886da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 388791a27b2aSJeff Layton if (IS_ERR(name)) 388891a27b2aSJeff Layton return PTR_ERR(name); 38892ad94ae6SAl Viro 38901da177e4SLinus Torvalds error = -EISDIR; 3891f5beed75SAl Viro if (type != LAST_NORM) 38921da177e4SLinus Torvalds goto exit1; 38930612d9fbSOGAWA Hirofumi 3894f5beed75SAl Viro error = mnt_want_write(path.mnt); 3895c30dabfeSJan Kara if (error) 3896c30dabfeSJan Kara goto exit1; 3897b21996e3SJ. Bruce Fields retry_deleg: 38985955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3899f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39001da177e4SLinus Torvalds error = PTR_ERR(dentry); 39011da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39021da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3903f5beed75SAl Viro if (last.name[last.len]) 390450338b88STörök Edwin goto slashes; 39051da177e4SLinus Torvalds inode = dentry->d_inode; 3906b18825a7SDavid Howells if (d_is_negative(dentry)) 3907e6bc45d6STheodore Ts'o goto slashes; 39087de9c6eeSAl Viro ihold(inode); 3909f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3910be6d3e56SKentaro Takeda if (error) 3911c30dabfeSJan Kara goto exit2; 3912f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39131da177e4SLinus Torvalds exit2: 39141da177e4SLinus Torvalds dput(dentry); 39151da177e4SLinus Torvalds } 39165955102cSAl Viro inode_unlock(path.dentry->d_inode); 39171da177e4SLinus Torvalds if (inode) 39181da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3919b21996e3SJ. Bruce Fields inode = NULL; 3920b21996e3SJ. Bruce Fields if (delegated_inode) { 39215a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3922b21996e3SJ. Bruce Fields if (!error) 3923b21996e3SJ. Bruce Fields goto retry_deleg; 3924b21996e3SJ. Bruce Fields } 3925f5beed75SAl Viro mnt_drop_write(path.mnt); 39261da177e4SLinus Torvalds exit1: 3927f5beed75SAl Viro path_put(&path); 39285d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39295d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39305d18f813SJeff Layton inode = NULL; 39315d18f813SJeff Layton goto retry; 39325d18f813SJeff Layton } 3933da2f1362SChristoph Hellwig putname(name); 39341da177e4SLinus Torvalds return error; 39351da177e4SLinus Torvalds 39361da177e4SLinus Torvalds slashes: 3937b18825a7SDavid Howells if (d_is_negative(dentry)) 3938b18825a7SDavid Howells error = -ENOENT; 393944b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3940b18825a7SDavid Howells error = -EISDIR; 3941b18825a7SDavid Howells else 3942b18825a7SDavid Howells error = -ENOTDIR; 39431da177e4SLinus Torvalds goto exit2; 39441da177e4SLinus Torvalds } 39451da177e4SLinus Torvalds 39462e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39475590ff0dSUlrich Drepper { 39485590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39495590ff0dSUlrich Drepper return -EINVAL; 39505590ff0dSUlrich Drepper 39515590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39525590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39535590ff0dSUlrich Drepper 3954da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39555590ff0dSUlrich Drepper } 39565590ff0dSUlrich Drepper 39573480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39585590ff0dSUlrich Drepper { 3959da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39605590ff0dSUlrich Drepper } 39615590ff0dSUlrich Drepper 3962db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39631da177e4SLinus Torvalds { 3964a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39651da177e4SLinus Torvalds 39661da177e4SLinus Torvalds if (error) 39671da177e4SLinus Torvalds return error; 39681da177e4SLinus Torvalds 3969acfa4380SAl Viro if (!dir->i_op->symlink) 39701da177e4SLinus Torvalds return -EPERM; 39711da177e4SLinus Torvalds 39721da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39731da177e4SLinus Torvalds if (error) 39741da177e4SLinus Torvalds return error; 39751da177e4SLinus Torvalds 39761da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3977a74574aaSStephen Smalley if (!error) 3978f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39791da177e4SLinus Torvalds return error; 39801da177e4SLinus Torvalds } 39814d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39821da177e4SLinus Torvalds 3983b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 3984b724e846SDominik Brodowski const char __user *newname) 39851da177e4SLinus Torvalds { 39862ad94ae6SAl Viro int error; 398791a27b2aSJeff Layton struct filename *from; 39886902d925SDave Hansen struct dentry *dentry; 3989dae6ad8fSAl Viro struct path path; 3990f46d3567SJeff Layton unsigned int lookup_flags = 0; 39911da177e4SLinus Torvalds 39921da177e4SLinus Torvalds from = getname(oldname); 39931da177e4SLinus Torvalds if (IS_ERR(from)) 39941da177e4SLinus Torvalds return PTR_ERR(from); 3995f46d3567SJeff Layton retry: 3996f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39971da177e4SLinus Torvalds error = PTR_ERR(dentry); 39986902d925SDave Hansen if (IS_ERR(dentry)) 3999dae6ad8fSAl Viro goto out_putname; 40006902d925SDave Hansen 400191a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4002a8104a9fSAl Viro if (!error) 400391a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4004921a1650SAl Viro done_path_create(&path, dentry); 4005f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4006f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4007f46d3567SJeff Layton goto retry; 4008f46d3567SJeff Layton } 40096902d925SDave Hansen out_putname: 40101da177e4SLinus Torvalds putname(from); 40111da177e4SLinus Torvalds return error; 40121da177e4SLinus Torvalds } 40131da177e4SLinus Torvalds 4014b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4015b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4016b724e846SDominik Brodowski { 4017b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4018b724e846SDominik Brodowski } 4019b724e846SDominik Brodowski 40203480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40215590ff0dSUlrich Drepper { 4022b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40235590ff0dSUlrich Drepper } 40245590ff0dSUlrich Drepper 4025146a8595SJ. Bruce Fields /** 4026146a8595SJ. Bruce Fields * vfs_link - create a new link 4027146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4028146a8595SJ. Bruce Fields * @dir: new parent 4029146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4030146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4031146a8595SJ. Bruce Fields * 4032146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4033146a8595SJ. Bruce Fields * 4034146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4035146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4036146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4037146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4038146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4039146a8595SJ. Bruce Fields * 4040146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4041146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4042146a8595SJ. Bruce Fields * to be NFS exported. 4043146a8595SJ. Bruce Fields */ 4044146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40451da177e4SLinus Torvalds { 40461da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40478de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40481da177e4SLinus Torvalds int error; 40491da177e4SLinus Torvalds 40501da177e4SLinus Torvalds if (!inode) 40511da177e4SLinus Torvalds return -ENOENT; 40521da177e4SLinus Torvalds 4053a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40541da177e4SLinus Torvalds if (error) 40551da177e4SLinus Torvalds return error; 40561da177e4SLinus Torvalds 40571da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40581da177e4SLinus Torvalds return -EXDEV; 40591da177e4SLinus Torvalds 40601da177e4SLinus Torvalds /* 40611da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40621da177e4SLinus Torvalds */ 40631da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40641da177e4SLinus Torvalds return -EPERM; 40650bd23d09SEric W. Biederman /* 40660bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 40670bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 40680bd23d09SEric W. Biederman * the vfs. 40690bd23d09SEric W. Biederman */ 40700bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 40710bd23d09SEric W. Biederman return -EPERM; 4072acfa4380SAl Viro if (!dir->i_op->link) 40731da177e4SLinus Torvalds return -EPERM; 40747e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40751da177e4SLinus Torvalds return -EPERM; 40761da177e4SLinus Torvalds 40771da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40781da177e4SLinus Torvalds if (error) 40791da177e4SLinus Torvalds return error; 40801da177e4SLinus Torvalds 40815955102cSAl Viro inode_lock(inode); 4082aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4083f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4084aae8a97dSAneesh Kumar K.V error = -ENOENT; 40858de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40868de52778SAl Viro error = -EMLINK; 4087146a8595SJ. Bruce Fields else { 4088146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4089146a8595SJ. Bruce Fields if (!error) 40901da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4091146a8595SJ. Bruce Fields } 4092f4e0c30cSAl Viro 4093f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4094f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4095f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4096f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4097f4e0c30cSAl Viro } 40985955102cSAl Viro inode_unlock(inode); 4099e31e14ecSStephen Smalley if (!error) 41007e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41011da177e4SLinus Torvalds return error; 41021da177e4SLinus Torvalds } 41034d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41041da177e4SLinus Torvalds 41051da177e4SLinus Torvalds /* 41061da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41071da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41081da177e4SLinus Torvalds * newname. --KAB 41091da177e4SLinus Torvalds * 41101da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41111da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41121da177e4SLinus Torvalds * and other special files. --ADM 41131da177e4SLinus Torvalds */ 411446ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 411546ea89ebSDominik Brodowski const char __user *newname, int flags) 41161da177e4SLinus Torvalds { 41171da177e4SLinus Torvalds struct dentry *new_dentry; 4118dae6ad8fSAl Viro struct path old_path, new_path; 4119146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 412011a7b371SAneesh Kumar K.V int how = 0; 41211da177e4SLinus Torvalds int error; 41221da177e4SLinus Torvalds 412311a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4124c04030e1SUlrich Drepper return -EINVAL; 412511a7b371SAneesh Kumar K.V /* 4126f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4127f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4128f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 412911a7b371SAneesh Kumar K.V */ 4130f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4131f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4132f0cc6ffbSLinus Torvalds return -ENOENT; 413311a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4134f0cc6ffbSLinus Torvalds } 4135c04030e1SUlrich Drepper 413611a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 413711a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4138442e31caSJeff Layton retry: 413911a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41401da177e4SLinus Torvalds if (error) 41412ad94ae6SAl Viro return error; 41422ad94ae6SAl Viro 4143442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4144442e31caSJeff Layton (how & LOOKUP_REVAL)); 41451da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41466902d925SDave Hansen if (IS_ERR(new_dentry)) 4147dae6ad8fSAl Viro goto out; 4148dae6ad8fSAl Viro 4149dae6ad8fSAl Viro error = -EXDEV; 4150dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4151dae6ad8fSAl Viro goto out_dput; 4152800179c9SKees Cook error = may_linkat(&old_path); 4153800179c9SKees Cook if (unlikely(error)) 4154800179c9SKees Cook goto out_dput; 4155dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4156be6d3e56SKentaro Takeda if (error) 4157a8104a9fSAl Viro goto out_dput; 4158146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 415975c3f29dSDave Hansen out_dput: 4160921a1650SAl Viro done_path_create(&new_path, new_dentry); 4161146a8595SJ. Bruce Fields if (delegated_inode) { 4162146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4163d22e6338SOleg Drokin if (!error) { 4164d22e6338SOleg Drokin path_put(&old_path); 4165146a8595SJ. Bruce Fields goto retry; 4166146a8595SJ. Bruce Fields } 4167d22e6338SOleg Drokin } 4168442e31caSJeff Layton if (retry_estale(error, how)) { 4169d22e6338SOleg Drokin path_put(&old_path); 4170442e31caSJeff Layton how |= LOOKUP_REVAL; 4171442e31caSJeff Layton goto retry; 4172442e31caSJeff Layton } 41731da177e4SLinus Torvalds out: 41742d8f3038SAl Viro path_put(&old_path); 41751da177e4SLinus Torvalds 41761da177e4SLinus Torvalds return error; 41771da177e4SLinus Torvalds } 41781da177e4SLinus Torvalds 417946ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 418046ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 418146ea89ebSDominik Brodowski { 418246ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 418346ea89ebSDominik Brodowski } 418446ea89ebSDominik Brodowski 41853480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41865590ff0dSUlrich Drepper { 418746ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41885590ff0dSUlrich Drepper } 41895590ff0dSUlrich Drepper 4190bc27027aSMiklos Szeredi /** 4191bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4192bc27027aSMiklos Szeredi * @old_dir: parent of source 4193bc27027aSMiklos Szeredi * @old_dentry: source 4194bc27027aSMiklos Szeredi * @new_dir: parent of destination 4195bc27027aSMiklos Szeredi * @new_dentry: destination 4196bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4197520c8b16SMiklos Szeredi * @flags: rename flags 4198bc27027aSMiklos Szeredi * 4199bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4200bc27027aSMiklos Szeredi * 4201bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4202bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4203bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4204bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4205bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4206bc27027aSMiklos Szeredi * so. 4207bc27027aSMiklos Szeredi * 4208bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4209bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4210bc27027aSMiklos Szeredi * to be NFS exported. 4211bc27027aSMiklos Szeredi * 42121da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42131da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42141da177e4SLinus Torvalds * Problems: 42150117d427SMauro Carvalho Chehab * 4216d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42171da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42181da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4219a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42201da177e4SLinus Torvalds * story. 42216cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42226cedba89SJ. Bruce Fields * and source (if it is not a directory). 42231b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42241da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42251da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4226a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42271da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42281da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42291da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4230a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42311da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42321da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42331da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4234e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42351b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42361da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4237c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42381da177e4SLinus Torvalds * locking]. 42391da177e4SLinus Torvalds */ 42401da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42418e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4242520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42431da177e4SLinus Torvalds { 42441da177e4SLinus Torvalds int error; 4245bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4246bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4247bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4248da1ce067SMiklos Szeredi bool new_is_dir = false; 4249da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 425049d31c2fSAl Viro struct name_snapshot old_name; 42511da177e4SLinus Torvalds 42528d3e2936SMiklos Szeredi if (source == target) 42531da177e4SLinus Torvalds return 0; 42541da177e4SLinus Torvalds 42551da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42561da177e4SLinus Torvalds if (error) 42571da177e4SLinus Torvalds return error; 42581da177e4SLinus Torvalds 4259da1ce067SMiklos Szeredi if (!target) { 4260a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4261da1ce067SMiklos Szeredi } else { 4262da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4263da1ce067SMiklos Szeredi 4264da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42651da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4266da1ce067SMiklos Szeredi else 4267da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4268da1ce067SMiklos Szeredi } 42691da177e4SLinus Torvalds if (error) 42701da177e4SLinus Torvalds return error; 42711da177e4SLinus Torvalds 42722773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 42731da177e4SLinus Torvalds return -EPERM; 42741da177e4SLinus Torvalds 4275bc27027aSMiklos Szeredi /* 4276bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4277bc27027aSMiklos Szeredi * we'll need to flip '..'. 4278bc27027aSMiklos Szeredi */ 4279da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4280da1ce067SMiklos Szeredi if (is_dir) { 4281bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4282bc27027aSMiklos Szeredi if (error) 4283bc27027aSMiklos Szeredi return error; 4284bc27027aSMiklos Szeredi } 4285da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4286da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4287da1ce067SMiklos Szeredi if (error) 4288da1ce067SMiklos Szeredi return error; 4289da1ce067SMiklos Szeredi } 4290da1ce067SMiklos Szeredi } 42910eeca283SRobert Love 42920b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42930b3974ebSMiklos Szeredi flags); 4294bc27027aSMiklos Szeredi if (error) 4295bc27027aSMiklos Szeredi return error; 4296bc27027aSMiklos Szeredi 429749d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4298bc27027aSMiklos Szeredi dget(new_dentry); 4299da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4300bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4301bc27027aSMiklos Szeredi else if (target) 43025955102cSAl Viro inode_lock(target); 4303bc27027aSMiklos Szeredi 4304bc27027aSMiklos Szeredi error = -EBUSY; 43057af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4306bc27027aSMiklos Szeredi goto out; 4307bc27027aSMiklos Szeredi 4308da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4309bc27027aSMiklos Szeredi error = -EMLINK; 4310da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4311bc27027aSMiklos Szeredi goto out; 4312da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4313da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4314da1ce067SMiklos Szeredi goto out; 4315da1ce067SMiklos Szeredi } 4316da1ce067SMiklos Szeredi if (!is_dir) { 4317bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4318bc27027aSMiklos Szeredi if (error) 4319bc27027aSMiklos Szeredi goto out; 4320da1ce067SMiklos Szeredi } 4321da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4322bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4323bc27027aSMiklos Szeredi if (error) 4324bc27027aSMiklos Szeredi goto out; 4325bc27027aSMiklos Szeredi } 4326520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4327520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4328bc27027aSMiklos Szeredi if (error) 4329bc27027aSMiklos Szeredi goto out; 4330bc27027aSMiklos Szeredi 4331da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43328767712fSAl Viro if (is_dir) { 43338767712fSAl Viro shrink_dcache_parent(new_dentry); 4334bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43358767712fSAl Viro } 4336bc27027aSMiklos Szeredi dont_mount(new_dentry); 43378ed936b5SEric W. Biederman detach_mounts(new_dentry); 4338bc27027aSMiklos Szeredi } 4339da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4340da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4341bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4342da1ce067SMiklos Szeredi else 4343da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4344da1ce067SMiklos Szeredi } 4345bc27027aSMiklos Szeredi out: 4346da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4347bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4348bc27027aSMiklos Szeredi else if (target) 43495955102cSAl Viro inode_unlock(target); 4350bc27027aSMiklos Szeredi dput(new_dentry); 4351da1ce067SMiklos Szeredi if (!error) { 4352f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4353da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4354da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4355f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4356da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4357da1ce067SMiklos Szeredi } 4358da1ce067SMiklos Szeredi } 435949d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 43600eeca283SRobert Love 43611da177e4SLinus Torvalds return error; 43621da177e4SLinus Torvalds } 43634d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43641da177e4SLinus Torvalds 4365ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4366ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 43671da177e4SLinus Torvalds { 43681da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43691da177e4SLinus Torvalds struct dentry *trap; 4370f5beed75SAl Viro struct path old_path, new_path; 4371f5beed75SAl Viro struct qstr old_last, new_last; 4372f5beed75SAl Viro int old_type, new_type; 43738e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 437491a27b2aSJeff Layton struct filename *from; 437591a27b2aSJeff Layton struct filename *to; 4376f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4377c6a94284SJeff Layton bool should_retry = false; 43782ad94ae6SAl Viro int error; 4379520c8b16SMiklos Szeredi 43800d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4381da1ce067SMiklos Szeredi return -EINVAL; 4382da1ce067SMiklos Szeredi 43830d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43840d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4385520c8b16SMiklos Szeredi return -EINVAL; 4386520c8b16SMiklos Szeredi 43870d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43880d7a8555SMiklos Szeredi return -EPERM; 43890d7a8555SMiklos Szeredi 4390f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4391f5beed75SAl Viro target_flags = 0; 4392f5beed75SAl Viro 4393c6a94284SJeff Layton retry: 4394c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4395c1d4dd27SAl Viro &old_path, &old_last, &old_type); 439691a27b2aSJeff Layton if (IS_ERR(from)) { 439791a27b2aSJeff Layton error = PTR_ERR(from); 43981da177e4SLinus Torvalds goto exit; 439991a27b2aSJeff Layton } 44001da177e4SLinus Torvalds 4401c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4402c1d4dd27SAl Viro &new_path, &new_last, &new_type); 440391a27b2aSJeff Layton if (IS_ERR(to)) { 440491a27b2aSJeff Layton error = PTR_ERR(to); 44051da177e4SLinus Torvalds goto exit1; 440691a27b2aSJeff Layton } 44071da177e4SLinus Torvalds 44081da177e4SLinus Torvalds error = -EXDEV; 4409f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44101da177e4SLinus Torvalds goto exit2; 44111da177e4SLinus Torvalds 44121da177e4SLinus Torvalds error = -EBUSY; 4413f5beed75SAl Viro if (old_type != LAST_NORM) 44141da177e4SLinus Torvalds goto exit2; 44151da177e4SLinus Torvalds 44160a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44170a7c3937SMiklos Szeredi error = -EEXIST; 4418f5beed75SAl Viro if (new_type != LAST_NORM) 44191da177e4SLinus Torvalds goto exit2; 44201da177e4SLinus Torvalds 4421f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4422c30dabfeSJan Kara if (error) 4423c30dabfeSJan Kara goto exit2; 4424c30dabfeSJan Kara 44258e6d782cSJ. Bruce Fields retry_deleg: 4426f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44271da177e4SLinus Torvalds 4428f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44291da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44301da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44311da177e4SLinus Torvalds goto exit3; 44321da177e4SLinus Torvalds /* source must exist */ 44331da177e4SLinus Torvalds error = -ENOENT; 4434b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44351da177e4SLinus Torvalds goto exit4; 4436f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44371da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44381da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44391da177e4SLinus Torvalds goto exit4; 44400a7c3937SMiklos Szeredi error = -EEXIST; 44410a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44420a7c3937SMiklos Szeredi goto exit5; 4443da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4444da1ce067SMiklos Szeredi error = -ENOENT; 4445da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4446da1ce067SMiklos Szeredi goto exit5; 4447da1ce067SMiklos Szeredi 4448da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4449da1ce067SMiklos Szeredi error = -ENOTDIR; 4450f5beed75SAl Viro if (new_last.name[new_last.len]) 4451da1ce067SMiklos Szeredi goto exit5; 4452da1ce067SMiklos Szeredi } 4453da1ce067SMiklos Szeredi } 44540a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44550a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44560a7c3937SMiklos Szeredi error = -ENOTDIR; 4457f5beed75SAl Viro if (old_last.name[old_last.len]) 44580a7c3937SMiklos Szeredi goto exit5; 4459f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44600a7c3937SMiklos Szeredi goto exit5; 44610a7c3937SMiklos Szeredi } 44620a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44630a7c3937SMiklos Szeredi error = -EINVAL; 44640a7c3937SMiklos Szeredi if (old_dentry == trap) 44650a7c3937SMiklos Szeredi goto exit5; 44661da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4467da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44681da177e4SLinus Torvalds error = -ENOTEMPTY; 44691da177e4SLinus Torvalds if (new_dentry == trap) 44701da177e4SLinus Torvalds goto exit5; 44711da177e4SLinus Torvalds 4472f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4473f5beed75SAl Viro &new_path, new_dentry, flags); 4474be6d3e56SKentaro Takeda if (error) 4475c30dabfeSJan Kara goto exit5; 4476f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4477f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4478520c8b16SMiklos Szeredi &delegated_inode, flags); 44791da177e4SLinus Torvalds exit5: 44801da177e4SLinus Torvalds dput(new_dentry); 44811da177e4SLinus Torvalds exit4: 44821da177e4SLinus Torvalds dput(old_dentry); 44831da177e4SLinus Torvalds exit3: 4484f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44858e6d782cSJ. Bruce Fields if (delegated_inode) { 44868e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44878e6d782cSJ. Bruce Fields if (!error) 44888e6d782cSJ. Bruce Fields goto retry_deleg; 44898e6d782cSJ. Bruce Fields } 4490f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44911da177e4SLinus Torvalds exit2: 4492c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4493c6a94284SJeff Layton should_retry = true; 4494f5beed75SAl Viro path_put(&new_path); 44952ad94ae6SAl Viro putname(to); 44961da177e4SLinus Torvalds exit1: 4497f5beed75SAl Viro path_put(&old_path); 44981da177e4SLinus Torvalds putname(from); 4499c6a94284SJeff Layton if (should_retry) { 4500c6a94284SJeff Layton should_retry = false; 4501c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4502c6a94284SJeff Layton goto retry; 4503c6a94284SJeff Layton } 45042ad94ae6SAl Viro exit: 45051da177e4SLinus Torvalds return error; 45061da177e4SLinus Torvalds } 45071da177e4SLinus Torvalds 4508ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4509ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4510ee81feb6SDominik Brodowski { 4511ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4512ee81feb6SDominik Brodowski } 4513ee81feb6SDominik Brodowski 4514520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4515520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4516520c8b16SMiklos Szeredi { 4517ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4518520c8b16SMiklos Szeredi } 4519520c8b16SMiklos Szeredi 4520a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45215590ff0dSUlrich Drepper { 4522ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45235590ff0dSUlrich Drepper } 45245590ff0dSUlrich Drepper 4525787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4526787fb6bcSMiklos Szeredi { 4527787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4528787fb6bcSMiklos Szeredi if (error) 4529787fb6bcSMiklos Szeredi return error; 4530787fb6bcSMiklos Szeredi 4531787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4532787fb6bcSMiklos Szeredi return -EPERM; 4533787fb6bcSMiklos Szeredi 4534787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4535787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4536787fb6bcSMiklos Szeredi } 4537787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4538787fb6bcSMiklos Szeredi 45395d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45401da177e4SLinus Torvalds { 45415d826c84SAl Viro int len = PTR_ERR(link); 45421da177e4SLinus Torvalds if (IS_ERR(link)) 45431da177e4SLinus Torvalds goto out; 45441da177e4SLinus Torvalds 45451da177e4SLinus Torvalds len = strlen(link); 45461da177e4SLinus Torvalds if (len > (unsigned) buflen) 45471da177e4SLinus Torvalds len = buflen; 45481da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45491da177e4SLinus Torvalds len = -EFAULT; 45501da177e4SLinus Torvalds out: 45511da177e4SLinus Torvalds return len; 45521da177e4SLinus Torvalds } 45531da177e4SLinus Torvalds 4554d60874cdSMiklos Szeredi /** 4555fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4556fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4557fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4558fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4559fd4a0edfSMiklos Szeredi * 4560fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4561fd4a0edfSMiklos Szeredi * 4562fd4a0edfSMiklos Szeredi * Does not call security hook. 4563fd4a0edfSMiklos Szeredi */ 4564fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4565fd4a0edfSMiklos Szeredi { 4566fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4567f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4568f2df5da6SAl Viro const char *link; 4569f2df5da6SAl Viro int res; 4570fd4a0edfSMiklos Szeredi 457176fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 457276fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 457376fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 457476fca90eSMiklos Szeredi 457576fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4576fd4a0edfSMiklos Szeredi return -EINVAL; 4577fd4a0edfSMiklos Szeredi 457876fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 457976fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 458076fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 458176fca90eSMiklos Szeredi } 458276fca90eSMiklos Szeredi 45834c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4584f2df5da6SAl Viro if (!link) { 4585f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4586f2df5da6SAl Viro if (IS_ERR(link)) 4587f2df5da6SAl Viro return PTR_ERR(link); 4588f2df5da6SAl Viro } 4589f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4590f2df5da6SAl Viro do_delayed_call(&done); 4591f2df5da6SAl Viro return res; 4592fd4a0edfSMiklos Szeredi } 4593fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 45941da177e4SLinus Torvalds 4595d60874cdSMiklos Szeredi /** 4596d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4597d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4598d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4599d60874cdSMiklos Szeredi * 4600d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4601d60874cdSMiklos Szeredi * 4602d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4603d60874cdSMiklos Szeredi * 4604d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4605d60874cdSMiklos Szeredi */ 4606d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4607d60874cdSMiklos Szeredi { 4608d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4609d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4610d60874cdSMiklos Szeredi 4611d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4612d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4613d60874cdSMiklos Szeredi if (!res) 4614d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4615d60874cdSMiklos Szeredi } 4616d60874cdSMiklos Szeredi return res; 4617d60874cdSMiklos Szeredi } 4618d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4619d60874cdSMiklos Szeredi 46201da177e4SLinus Torvalds /* get the link contents into pagecache */ 46216b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4622fceef393SAl Viro struct delayed_call *callback) 46231da177e4SLinus Torvalds { 4624ebd09abbSDuane Griffin char *kaddr; 46251da177e4SLinus Torvalds struct page *page; 46266b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46276b255391SAl Viro 4628d3883d4fSAl Viro if (!dentry) { 4629d3883d4fSAl Viro page = find_get_page(mapping, 0); 4630d3883d4fSAl Viro if (!page) 46316b255391SAl Viro return ERR_PTR(-ECHILD); 4632d3883d4fSAl Viro if (!PageUptodate(page)) { 4633d3883d4fSAl Viro put_page(page); 4634d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4635d3883d4fSAl Viro } 4636d3883d4fSAl Viro } else { 4637090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46381da177e4SLinus Torvalds if (IS_ERR(page)) 46396fe6900eSNick Piggin return (char*)page; 4640d3883d4fSAl Viro } 4641fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 464221fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 464321fc61c7SAl Viro kaddr = page_address(page); 46446b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4645ebd09abbSDuane Griffin return kaddr; 46461da177e4SLinus Torvalds } 46471da177e4SLinus Torvalds 46486b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46491da177e4SLinus Torvalds 4650fceef393SAl Viro void page_put_link(void *arg) 46511da177e4SLinus Torvalds { 4652fceef393SAl Viro put_page(arg); 46531da177e4SLinus Torvalds } 46544d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46551da177e4SLinus Torvalds 4656aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4657aa80deabSAl Viro { 4658fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46596b255391SAl Viro int res = readlink_copy(buffer, buflen, 46606b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4661fceef393SAl Viro &done)); 4662fceef393SAl Viro do_delayed_call(&done); 4663aa80deabSAl Viro return res; 4664aa80deabSAl Viro } 4665aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4666aa80deabSAl Viro 466754566b2cSNick Piggin /* 466854566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 466954566b2cSNick Piggin */ 467054566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46711da177e4SLinus Torvalds { 46721da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46730adb25d2SKirill Korotaev struct page *page; 4674afddba49SNick Piggin void *fsdata; 4675beb497abSDmitriy Monakhov int err; 4676c718a975STetsuo Handa unsigned int flags = 0; 467754566b2cSNick Piggin if (nofs) 467854566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46791da177e4SLinus Torvalds 46807e53cac4SNeilBrown retry: 4681afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 468254566b2cSNick Piggin flags, &page, &fsdata); 46831da177e4SLinus Torvalds if (err) 4684afddba49SNick Piggin goto fail; 4685afddba49SNick Piggin 468621fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4687afddba49SNick Piggin 4688afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4689afddba49SNick Piggin page, fsdata); 46901da177e4SLinus Torvalds if (err < 0) 46911da177e4SLinus Torvalds goto fail; 4692afddba49SNick Piggin if (err < len-1) 4693afddba49SNick Piggin goto retry; 4694afddba49SNick Piggin 46951da177e4SLinus Torvalds mark_inode_dirty(inode); 46961da177e4SLinus Torvalds return 0; 46971da177e4SLinus Torvalds fail: 46981da177e4SLinus Torvalds return err; 46991da177e4SLinus Torvalds } 47004d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47011da177e4SLinus Torvalds 47020adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47030adb25d2SKirill Korotaev { 47040adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4705c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47060adb25d2SKirill Korotaev } 47074d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47080adb25d2SKirill Korotaev 470992e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47106b255391SAl Viro .get_link = page_get_link, 47111da177e4SLinus Torvalds }; 47121da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4713