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 136631e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 136731e6b01fSNick Piggin { 13684023bfc9SAl Viro struct inode *inode = nd->inode; 136931e6b01fSNick Piggin 137031e6b01fSNick Piggin while (1) { 1371adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1372adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1373adb21d2bSAleksa Sarai return -ECHILD; 137431e6b01fSNick Piggin break; 1375adb21d2bSAleksa Sarai } 137631e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 137731e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 137831e6b01fSNick Piggin struct dentry *parent = old->d_parent; 137931e6b01fSNick Piggin unsigned seq; 138031e6b01fSNick Piggin 13814023bfc9SAl Viro inode = parent->d_inode; 138231e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 1383aed434adSAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 1384aed434adSAl Viro return -ECHILD; 138531e6b01fSNick Piggin nd->path.dentry = parent; 138631e6b01fSNick Piggin nd->seq = seq; 13876b03f7edSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 13882b98149cSAleksa Sarai return -ECHILD; 138931e6b01fSNick Piggin break; 1390aed434adSAl Viro } else { 1391aed434adSAl Viro struct mount *mnt = real_mount(nd->path.mnt); 1392aed434adSAl Viro struct mount *mparent = mnt->mnt_parent; 1393aed434adSAl Viro struct dentry *mountpoint = mnt->mnt_mountpoint; 1394aed434adSAl Viro struct inode *inode2 = mountpoint->d_inode; 1395aed434adSAl Viro unsigned seq = read_seqcount_begin(&mountpoint->d_seq); 1396aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1397aed434adSAl Viro return -ECHILD; 1398aed434adSAl Viro if (&mparent->mnt == nd->path.mnt) 139931e6b01fSNick Piggin break; 140072ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 140172ba2929SAleksa Sarai return -ECHILD; 1402aed434adSAl Viro /* we know that mountpoint was pinned */ 1403aed434adSAl Viro nd->path.dentry = mountpoint; 1404aed434adSAl Viro nd->path.mnt = &mparent->mnt; 1405aed434adSAl Viro inode = inode2; 1406aed434adSAl Viro nd->seq = seq; 140731e6b01fSNick Piggin } 1408aed434adSAl Viro } 1409aed434adSAl Viro while (unlikely(d_mountpoint(nd->path.dentry))) { 1410b37199e6SAl Viro struct mount *mounted; 1411b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1412aed434adSAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1413aed434adSAl Viro return -ECHILD; 1414b37199e6SAl Viro if (!mounted) 1415b37199e6SAl Viro break; 141672ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 141772ba2929SAleksa Sarai return -ECHILD; 1418b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1419b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 14204023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1421b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1422b37199e6SAl Viro } 14234023bfc9SAl Viro nd->inode = inode; 142431e6b01fSNick Piggin return 0; 142531e6b01fSNick Piggin } 142631e6b01fSNick Piggin 14279875cf80SDavid Howells /* 14289875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 14299875cf80SDavid Howells */ 14309875cf80SDavid Howells static void follow_mount(struct path *path) 14319875cf80SDavid Howells { 14329875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 14339875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 14349875cf80SDavid Howells if (!mounted) 14359875cf80SDavid Howells break; 14369875cf80SDavid Howells dput(path->dentry); 14379875cf80SDavid Howells mntput(path->mnt); 14389875cf80SDavid Howells path->mnt = mounted; 14399875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 14409875cf80SDavid Howells } 14419875cf80SDavid Howells } 14429875cf80SDavid Howells 1443397d425dSEric W. Biederman static int follow_dotdot(struct nameidata *nd) 14441da177e4SLinus Torvalds { 144563b27720SAl Viro struct dentry *parent; 14461da177e4SLinus Torvalds while (1) { 1447adb21d2bSAleksa Sarai if (path_equal(&nd->path, &nd->root)) { 1448adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 1449adb21d2bSAleksa Sarai return -EXDEV; 14501da177e4SLinus Torvalds break; 1451adb21d2bSAleksa Sarai } 14524ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 1453a6a7eb76SAl Viro /* rare case of legitimate dget_parent()... */ 1454a6a7eb76SAl Viro parent = dget_parent(nd->path.dentry); 1455a6a7eb76SAl Viro 1456a6a7eb76SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1457a6a7eb76SAl Viro dput(parent); 145863b27720SAl Viro return -ENOENT; 1459a6a7eb76SAl Viro } 146063b27720SAl Viro dput(nd->path.dentry); 146163b27720SAl Viro nd->path.dentry = parent; 14621da177e4SLinus Torvalds break; 14631da177e4SLinus Torvalds } 14643088dd70SAl Viro if (!follow_up(&nd->path)) 14651da177e4SLinus Torvalds break; 146672ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 146772ba2929SAleksa Sarai return -EXDEV; 14681da177e4SLinus Torvalds } 146979ed0226SAl Viro follow_mount(&nd->path); 147031e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 1471397d425dSEric W. Biederman return 0; 14721da177e4SLinus Torvalds } 14731da177e4SLinus Torvalds 14741da177e4SLinus Torvalds /* 1475f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1476f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1477baa03890SNick Piggin */ 1478e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1479e3c13928SAl Viro struct dentry *dir, 14806c51e513SAl Viro unsigned int flags) 1481baa03890SNick Piggin { 1482a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1483bad61189SMiklos Szeredi if (dentry) { 1484a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1485bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 148674ff0ffcSAl Viro if (!error) 14875542aa2fSEric W. Biederman d_invalidate(dentry); 1488bad61189SMiklos Szeredi dput(dentry); 148974ff0ffcSAl Viro return ERR_PTR(error); 1490bad61189SMiklos Szeredi } 1491bad61189SMiklos Szeredi } 1492baa03890SNick Piggin return dentry; 1493baa03890SNick Piggin } 1494baa03890SNick Piggin 1495baa03890SNick Piggin /* 1496a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1497a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1498a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1499a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1500a03ece5fSAl Viro * at all. 150144396f4bSJosef Bacik */ 1502a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1503a03ece5fSAl Viro struct dentry *base, unsigned int flags) 150444396f4bSJosef Bacik { 1505a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 150644396f4bSJosef Bacik struct dentry *old; 1507a03ece5fSAl Viro struct inode *dir = base->d_inode; 1508a03ece5fSAl Viro 1509a03ece5fSAl Viro if (dentry) 1510a03ece5fSAl Viro return dentry; 151144396f4bSJosef Bacik 151244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1513a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 151444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1515a03ece5fSAl Viro 1516a03ece5fSAl Viro dentry = d_alloc(base, name); 1517a03ece5fSAl Viro if (unlikely(!dentry)) 1518a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 151944396f4bSJosef Bacik 152072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 152144396f4bSJosef Bacik if (unlikely(old)) { 152244396f4bSJosef Bacik dput(dentry); 152344396f4bSJosef Bacik dentry = old; 152444396f4bSJosef Bacik } 152544396f4bSJosef Bacik return dentry; 152644396f4bSJosef Bacik } 152744396f4bSJosef Bacik 152820e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 152920e34357SAl Viro struct inode **inode, 1530254cf582SAl Viro unsigned *seqp) 15311da177e4SLinus Torvalds { 153231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 15335a18fff2SAl Viro int status = 1; 15349875cf80SDavid Howells 15353cac260aSAl Viro /* 1536b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 15375d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 15385d0f49c1SAl Viro * going to fall back to non-racy lookup. 1539b04f784eSNick Piggin */ 154031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 154131e6b01fSNick Piggin unsigned seq; 1542da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 15435d0f49c1SAl Viro if (unlikely(!dentry)) { 15444675ac39SAl Viro if (unlazy_walk(nd)) 154520e34357SAl Viro return ERR_PTR(-ECHILD); 154620e34357SAl Viro return NULL; 15475d0f49c1SAl Viro } 15485a18fff2SAl Viro 154912f8ad4bSLinus Torvalds /* 155012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 155112f8ad4bSLinus Torvalds * the dentry name information from lookup. 155212f8ad4bSLinus Torvalds */ 155363afdfc7SDavid Howells *inode = d_backing_inode(dentry); 15545d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 155520e34357SAl Viro return ERR_PTR(-ECHILD); 155612f8ad4bSLinus Torvalds 155712f8ad4bSLinus Torvalds /* 155812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 155912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 156012f8ad4bSLinus Torvalds * 156112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 156212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 156312f8ad4bSLinus Torvalds */ 15645d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 156520e34357SAl Viro return ERR_PTR(-ECHILD); 15665a18fff2SAl Viro 1567254cf582SAl Viro *seqp = seq; 15684ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1569c153007bSAl Viro if (likely(status > 0)) 157020e34357SAl Viro return dentry; 15714675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 157220e34357SAl Viro return ERR_PTR(-ECHILD); 1573209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1574209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1575209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15765a18fff2SAl Viro } else { 1577e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 157881e6f520SAl Viro if (unlikely(!dentry)) 157920e34357SAl Viro return NULL; 15804ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15815d0f49c1SAl Viro } 15825a18fff2SAl Viro if (unlikely(status <= 0)) { 1583e9742b53SAl Viro if (!status) 15845d0f49c1SAl Viro d_invalidate(dentry); 15855a18fff2SAl Viro dput(dentry); 158620e34357SAl Viro return ERR_PTR(status); 15875a18fff2SAl Viro } 158820e34357SAl Viro return dentry; 1589697f514dSMiklos Szeredi } 1590697f514dSMiklos Szeredi 1591697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 159288d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1593e3c13928SAl Viro struct dentry *dir, 1594e3c13928SAl Viro unsigned int flags) 1595697f514dSMiklos Szeredi { 159688d8331aSAl Viro struct dentry *dentry, *old; 15971936386eSAl Viro struct inode *inode = dir->d_inode; 1598d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15991936386eSAl Viro 16001936386eSAl Viro /* Don't go there if it's already dead */ 160194bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 160288d8331aSAl Viro return ERR_PTR(-ENOENT); 160394bdd655SAl Viro again: 1604d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 160594bdd655SAl Viro if (IS_ERR(dentry)) 160688d8331aSAl Viro return dentry; 160794bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1608949a852eSAl Viro int error = d_revalidate(dentry, flags); 1609949a852eSAl Viro if (unlikely(error <= 0)) { 161094bdd655SAl Viro if (!error) { 1611949a852eSAl Viro d_invalidate(dentry); 1612949a852eSAl Viro dput(dentry); 161394bdd655SAl Viro goto again; 161494bdd655SAl Viro } 161594bdd655SAl Viro dput(dentry); 1616949a852eSAl Viro dentry = ERR_PTR(error); 1617949a852eSAl Viro } 161894bdd655SAl Viro } else { 16191936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 162085c7f810SAl Viro d_lookup_done(dentry); 16211936386eSAl Viro if (unlikely(old)) { 16221936386eSAl Viro dput(dentry); 16231936386eSAl Viro dentry = old; 1624949a852eSAl Viro } 1625949a852eSAl Viro } 1626e3c13928SAl Viro return dentry; 16271da177e4SLinus Torvalds } 16281da177e4SLinus Torvalds 162988d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 163088d8331aSAl Viro struct dentry *dir, 163188d8331aSAl Viro unsigned int flags) 163288d8331aSAl Viro { 163388d8331aSAl Viro struct inode *inode = dir->d_inode; 163488d8331aSAl Viro struct dentry *res; 163588d8331aSAl Viro inode_lock_shared(inode); 163688d8331aSAl Viro res = __lookup_slow(name, dir, flags); 163788d8331aSAl Viro inode_unlock_shared(inode); 163888d8331aSAl Viro return res; 163988d8331aSAl Viro } 164088d8331aSAl Viro 164152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 164252094c8aSAl Viro { 164352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 16444ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 164552094c8aSAl Viro if (err != -ECHILD) 164652094c8aSAl Viro return err; 16474675ac39SAl Viro if (unlazy_walk(nd)) 164852094c8aSAl Viro return -ECHILD; 164952094c8aSAl Viro } 16504ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 165152094c8aSAl Viro } 165252094c8aSAl Viro 16539856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 16549856fa1bSAl Viro { 16559856fa1bSAl Viro if (type == LAST_DOTDOT) { 1656740a1678SAleksa Sarai int error = 0; 1657740a1678SAleksa Sarai 1658740a1678SAleksa Sarai if (!nd->root.mnt) { 1659740a1678SAleksa Sarai error = set_root(nd); 1660740a1678SAleksa Sarai if (error) 1661740a1678SAleksa Sarai return error; 1662740a1678SAleksa Sarai } 1663ab87f9a5SAleksa Sarai if (nd->flags & LOOKUP_RCU) 1664ab87f9a5SAleksa Sarai error = follow_dotdot_rcu(nd); 1665ab87f9a5SAleksa Sarai else 1666ab87f9a5SAleksa Sarai error = follow_dotdot(nd); 1667ab87f9a5SAleksa Sarai if (error) 1668ab87f9a5SAleksa Sarai return error; 1669ab87f9a5SAleksa Sarai 1670ab87f9a5SAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1671ab87f9a5SAleksa Sarai /* 1672ab87f9a5SAleksa Sarai * If there was a racing rename or mount along our 1673ab87f9a5SAleksa Sarai * path, then we can't be sure that ".." hasn't jumped 1674ab87f9a5SAleksa Sarai * above nd->root (and so userspace should retry or use 1675ab87f9a5SAleksa Sarai * some fallback). 1676ab87f9a5SAleksa Sarai */ 1677ab87f9a5SAleksa Sarai smp_rmb(); 1678ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 1679ab87f9a5SAleksa Sarai return -EAGAIN; 1680ab87f9a5SAleksa Sarai if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 1681ab87f9a5SAleksa Sarai return -EAGAIN; 1682ab87f9a5SAleksa Sarai } 16839856fa1bSAl Viro } 16849856fa1bSAl Viro return 0; 16859856fa1bSAl Viro } 16869856fa1bSAl Viro 1687b1a81972SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 1688b1a81972SAl Viro 168906708adbSAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 1690b1a81972SAl Viro struct inode *inode, unsigned seq, int flags) 1691d63ff28fSAl Viro { 16921cf2665bSAl Viro struct saved *last; 1693ad6cc4c3SAl Viro const char *res; 1694ad6cc4c3SAl Viro int error; 1695ad6cc4c3SAl Viro 1696756daf26SNeilBrown if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { 1697626de996SAl Viro path_to_nameidata(link, nd); 169806708adbSAl Viro return ERR_PTR(-ELOOP); 1699626de996SAl Viro } 1700bc40aee0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1701cd179f44SAl Viro if (link->mnt == nd->path.mnt) 1702cd179f44SAl Viro mntget(link->mnt); 17037973387aSAl Viro } 1704626de996SAl Viro error = nd_alloc_stack(nd); 1705626de996SAl Viro if (unlikely(error)) { 1706bc40aee0SAl Viro if (error == -ECHILD) { 1707ad1633a1SAl Viro if (unlikely(!legitimize_path(nd, link, seq))) { 1708ad1633a1SAl Viro drop_links(nd); 1709ad1633a1SAl Viro nd->depth = 0; 1710ad1633a1SAl Viro nd->flags &= ~LOOKUP_RCU; 1711ad1633a1SAl Viro nd->path.mnt = NULL; 1712ad1633a1SAl Viro nd->path.dentry = NULL; 1713ad1633a1SAl Viro rcu_read_unlock(); 17144675ac39SAl Viro } else if (likely(unlazy_walk(nd)) == 0) 1715bc40aee0SAl Viro error = nd_alloc_stack(nd); 1716bc40aee0SAl Viro } 1717bc40aee0SAl Viro if (error) { 1718cd179f44SAl Viro path_put(link); 171906708adbSAl Viro return ERR_PTR(error); 1720626de996SAl Viro } 1721bc40aee0SAl Viro } 1722626de996SAl Viro 1723ab104923SAl Viro last = nd->stack + nd->depth++; 17241cf2665bSAl Viro last->link = *link; 1725fceef393SAl Viro clear_delayed_call(&last->done); 17260450b2d1SAl Viro last->seq = seq; 1727ad6cc4c3SAl Viro 1728b1a81972SAl Viro if (flags & WALK_TRAILING) { 1729ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1730ad6cc4c3SAl Viro if (unlikely(error)) 1731ad6cc4c3SAl Viro return ERR_PTR(error); 1732ad6cc4c3SAl Viro } 1733ad6cc4c3SAl Viro 1734ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1735ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1736ad6cc4c3SAl Viro 1737ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1738ad6cc4c3SAl Viro touch_atime(&last->link); 1739ad6cc4c3SAl Viro cond_resched(); 1740ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1741ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1742ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1743ad6cc4c3SAl Viro touch_atime(&last->link); 1744ad6cc4c3SAl Viro } 1745ad6cc4c3SAl Viro 1746ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1747ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1748ad6cc4c3SAl Viro if (unlikely(error)) 1749ad6cc4c3SAl Viro return ERR_PTR(error); 1750ad6cc4c3SAl Viro 1751ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1752ad6cc4c3SAl Viro if (!res) { 1753ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1754ad6cc4c3SAl Viro struct delayed_call *); 1755ad6cc4c3SAl Viro get = inode->i_op->get_link; 1756ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1757ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1758ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1759ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1760ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1761ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1762ad6cc4c3SAl Viro } 1763ad6cc4c3SAl Viro } else { 1764ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1765ad6cc4c3SAl Viro } 1766ad6cc4c3SAl Viro if (!res) 1767ad6cc4c3SAl Viro goto all_done; 1768ad6cc4c3SAl Viro if (IS_ERR(res)) 1769ad6cc4c3SAl Viro return res; 1770ad6cc4c3SAl Viro } 1771ad6cc4c3SAl Viro if (*res == '/') { 1772ad6cc4c3SAl Viro error = nd_jump_root(nd); 1773ad6cc4c3SAl Viro if (unlikely(error)) 1774ad6cc4c3SAl Viro return ERR_PTR(error); 1775ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1776ad6cc4c3SAl Viro ; 1777ad6cc4c3SAl Viro } 1778ad6cc4c3SAl Viro if (*res) 1779ad6cc4c3SAl Viro return res; 1780ad6cc4c3SAl Viro all_done: // pure jump 1781ad6cc4c3SAl Viro put_link(nd); 1782ad6cc4c3SAl Viro return NULL; 1783d63ff28fSAl Viro } 1784d63ff28fSAl Viro 17853ddcd056SLinus Torvalds /* 17863ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 17873ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 17883ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 17893ddcd056SLinus Torvalds * for the common case. 17903ddcd056SLinus Torvalds */ 1791b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1792cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 17933ddcd056SLinus Torvalds { 1794cbae4d12SAl Viro struct path path; 1795cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1796cbae4d12SAl Viro 1797cbae4d12SAl Viro if (err < 0) 1798b0417d2cSAl Viro return ERR_PTR(err); 1799cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 18008c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1801aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 18028f64fb1cSAl Viro /* not a symlink or should not follow */ 1803cbae4d12SAl Viro path_to_nameidata(&path, nd); 18048f64fb1cSAl Viro nd->inode = inode; 18058f64fb1cSAl Viro nd->seq = seq; 1806b0417d2cSAl Viro return NULL; 18078f64fb1cSAl Viro } 1808a7f77542SAl Viro /* make sure that d_is_symlink above matches inode */ 1809a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 1810cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1811b0417d2cSAl Viro return ERR_PTR(-ECHILD); 1812a7f77542SAl Viro } 1813b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 18143ddcd056SLinus Torvalds } 18153ddcd056SLinus Torvalds 181692d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1817ce57dfc1SAl Viro { 1818db3c9adeSAl Viro struct dentry *dentry; 1819ce57dfc1SAl Viro struct inode *inode; 1820254cf582SAl Viro unsigned seq; 1821ce57dfc1SAl Viro int err; 1822ce57dfc1SAl Viro /* 1823ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1824ce57dfc1SAl Viro * to be able to know about the current root directory and 1825ce57dfc1SAl Viro * parent relationships. 1826ce57dfc1SAl Viro */ 18274693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18281c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18294693a547SAl Viro put_link(nd); 183056676ec3SAl Viro err = handle_dots(nd, nd->last_type); 183192d27016SAl Viro return ERR_PTR(err); 18324693a547SAl Viro } 183320e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 183420e34357SAl Viro if (IS_ERR(dentry)) 183592d27016SAl Viro return ERR_CAST(dentry); 183620e34357SAl Viro if (unlikely(!dentry)) { 1837db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1838db3c9adeSAl Viro if (IS_ERR(dentry)) 183992d27016SAl Viro return ERR_CAST(dentry); 184020e34357SAl Viro } 184156676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 184256676ec3SAl Viro put_link(nd); 1843b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1844ce57dfc1SAl Viro } 1845ce57dfc1SAl Viro 18461da177e4SLinus Torvalds /* 1847bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1848bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1849bfcfaa77SLinus Torvalds * 1850bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1851bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1852bfcfaa77SLinus Torvalds * fast. 1853bfcfaa77SLinus Torvalds * 1854bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1855bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1856bfcfaa77SLinus Torvalds * crossing operation. 1857bfcfaa77SLinus Torvalds * 1858bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1859bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1860bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1861bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1862bfcfaa77SLinus Torvalds */ 1863bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1864bfcfaa77SLinus Torvalds 1865f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1866bfcfaa77SLinus Torvalds 1867468a9428SGeorge Spelvin #ifdef HASH_MIX 1868bfcfaa77SLinus Torvalds 1869468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1870468a9428SGeorge Spelvin 1871468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18722a18da7aSGeorge Spelvin /* 18732a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18742a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18752a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 18762a18da7aSGeorge Spelvin * and no temporaries. 18772a18da7aSGeorge Spelvin * 18782a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 18792a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 18802a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 18812a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 18822a18da7aSGeorge Spelvin * 18832a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 18842a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 18852a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 18862a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 18872a18da7aSGeorge Spelvin * 18882a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 18892a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 18902a18da7aSGeorge Spelvin * toggling any given output bit. 18912a18da7aSGeorge Spelvin * 18922a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 18932a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 18942a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 18952a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 18962a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 18972a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 18982a18da7aSGeorge Spelvin * Perfect: 8192 258048 18992a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19002a18da7aSGeorge Spelvin */ 19012a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19022a18da7aSGeorge Spelvin ( x ^= (a), \ 19032a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19042a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19052a18da7aSGeorge Spelvin y *= 9 ) 1906bfcfaa77SLinus Torvalds 19070fed3ac8SGeorge Spelvin /* 19082a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19092a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19102a18da7aSGeorge Spelvin * work done before the hash value is used. 19110fed3ac8SGeorge Spelvin */ 19122a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19130fed3ac8SGeorge Spelvin { 19142a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19152a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19162a18da7aSGeorge Spelvin return y >> 32; 19170fed3ac8SGeorge Spelvin } 19180fed3ac8SGeorge Spelvin 1919bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1920bfcfaa77SLinus Torvalds 19212a18da7aSGeorge Spelvin /* 19222a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19232a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19242a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19252a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19262a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19272a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19282a18da7aSGeorge Spelvin * Perfect: 2048 31744 19292a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19302a18da7aSGeorge Spelvin */ 19312a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19322a18da7aSGeorge Spelvin ( x ^= (a), \ 19332a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19342a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19352a18da7aSGeorge Spelvin y *= 9 ) 1936bfcfaa77SLinus Torvalds 19372a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19380fed3ac8SGeorge Spelvin { 19392a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19402a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19410fed3ac8SGeorge Spelvin } 19420fed3ac8SGeorge Spelvin 1943bfcfaa77SLinus Torvalds #endif 1944bfcfaa77SLinus Torvalds 19452a18da7aSGeorge Spelvin /* 19462a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19472a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19482a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19492a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19502a18da7aSGeorge Spelvin * finds the delimiter after the name. 19512a18da7aSGeorge Spelvin */ 19528387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1953bfcfaa77SLinus Torvalds { 19548387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1955bfcfaa77SLinus Torvalds 1956bfcfaa77SLinus Torvalds for (;;) { 1957fcfd2fbfSGeorge Spelvin if (!len) 1958fcfd2fbfSGeorge Spelvin goto done; 1959e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1960bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1961bfcfaa77SLinus Torvalds break; 19622a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1963bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1964bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1965bfcfaa77SLinus Torvalds } 19662a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1967bfcfaa77SLinus Torvalds done: 19682a18da7aSGeorge Spelvin return fold_hash(x, y); 1969bfcfaa77SLinus Torvalds } 1970bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1971bfcfaa77SLinus Torvalds 1972fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19738387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1974fcfd2fbfSGeorge Spelvin { 19758387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 19768387ff25SLinus Torvalds unsigned long adata, mask, len; 1977fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1978fcfd2fbfSGeorge Spelvin 19798387ff25SLinus Torvalds len = 0; 19808387ff25SLinus Torvalds goto inside; 19818387ff25SLinus Torvalds 1982fcfd2fbfSGeorge Spelvin do { 19832a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1984fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 19858387ff25SLinus Torvalds inside: 1986fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 1987fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 1988fcfd2fbfSGeorge Spelvin 1989fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 1990fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 19912a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 1992fcfd2fbfSGeorge Spelvin 19932a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 1994fcfd2fbfSGeorge Spelvin } 1995fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 1996fcfd2fbfSGeorge Spelvin 1997bfcfaa77SLinus Torvalds /* 1998bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1999d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2000bfcfaa77SLinus Torvalds */ 20018387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2002bfcfaa77SLinus Torvalds { 20038387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20048387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 200536126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2006bfcfaa77SLinus Torvalds 20078387ff25SLinus Torvalds len = 0; 20088387ff25SLinus Torvalds goto inside; 20098387ff25SLinus Torvalds 2010bfcfaa77SLinus Torvalds do { 20112a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2012bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20138387ff25SLinus Torvalds inside: 2014e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 201536126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 201636126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2017bfcfaa77SLinus Torvalds 201836126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 201936126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 202036126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20212a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 202236126f8fSLinus Torvalds 20232a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2024bfcfaa77SLinus Torvalds } 2025bfcfaa77SLinus Torvalds 20262a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2027bfcfaa77SLinus Torvalds 2028fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20298387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20300145acc2SLinus Torvalds { 20318387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20320145acc2SLinus Torvalds while (len--) 2033fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20340145acc2SLinus Torvalds return end_name_hash(hash); 20350145acc2SLinus Torvalds } 2036ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20370145acc2SLinus Torvalds 2038fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20398387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2040fcfd2fbfSGeorge Spelvin { 20418387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2042fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2043fcfd2fbfSGeorge Spelvin 2044fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2045e0ab7af9SGeorge Spelvin while (c) { 2046fcfd2fbfSGeorge Spelvin len++; 2047fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2048fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2049e0ab7af9SGeorge Spelvin } 2050fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2051fcfd2fbfSGeorge Spelvin } 2052f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2053fcfd2fbfSGeorge Spelvin 20543ddcd056SLinus Torvalds /* 2055200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2056200e9ef7SLinus Torvalds * one character. 2057200e9ef7SLinus Torvalds */ 20588387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2059200e9ef7SLinus Torvalds { 20608387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2061200e9ef7SLinus Torvalds unsigned long len = 0, c; 2062200e9ef7SLinus Torvalds 2063200e9ef7SLinus Torvalds c = (unsigned char)*name; 2064200e9ef7SLinus Torvalds do { 2065200e9ef7SLinus Torvalds len++; 2066200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2067200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2068200e9ef7SLinus Torvalds } while (c && c != '/'); 2069d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2070200e9ef7SLinus Torvalds } 2071200e9ef7SLinus Torvalds 2072bfcfaa77SLinus Torvalds #endif 2073bfcfaa77SLinus Torvalds 2074200e9ef7SLinus Torvalds /* 20751da177e4SLinus Torvalds * Name resolution. 2076ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2077ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 20781da177e4SLinus Torvalds * 2079ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2080ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 20811da177e4SLinus Torvalds */ 20826de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 20831da177e4SLinus Torvalds { 2084d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 20851da177e4SLinus Torvalds int err; 20861da177e4SLinus Torvalds 2087b4c03536SAl Viro nd->last_type = LAST_ROOT; 2088c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 20899b5858e9SAl Viro if (IS_ERR(name)) 20909b5858e9SAl Viro return PTR_ERR(name); 20911da177e4SLinus Torvalds while (*name=='/') 20921da177e4SLinus Torvalds name++; 20931da177e4SLinus Torvalds if (!*name) 20949e18f10aSAl Viro return 0; 20951da177e4SLinus Torvalds 20961da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 20971da177e4SLinus Torvalds for(;;) { 209892d27016SAl Viro const char *link; 2099d6bb3e90SLinus Torvalds u64 hash_len; 2100fe479a58SAl Viro int type; 21011da177e4SLinus Torvalds 210252094c8aSAl Viro err = may_lookup(nd); 21031da177e4SLinus Torvalds if (err) 21043595e234SAl Viro return err; 21051da177e4SLinus Torvalds 21068387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21071da177e4SLinus Torvalds 2108fe479a58SAl Viro type = LAST_NORM; 2109d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2110fe479a58SAl Viro case 2: 2111200e9ef7SLinus Torvalds if (name[1] == '.') { 2112fe479a58SAl Viro type = LAST_DOTDOT; 211316c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 211416c2cd71SAl Viro } 2115fe479a58SAl Viro break; 2116fe479a58SAl Viro case 1: 2117fe479a58SAl Viro type = LAST_DOT; 2118fe479a58SAl Viro } 21195a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21205a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 212116c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21225a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2123a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2124da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21255a202bcdSAl Viro if (err < 0) 21263595e234SAl Viro return err; 2127d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2128d6bb3e90SLinus Torvalds name = this.name; 21295a202bcdSAl Viro } 21305a202bcdSAl Viro } 2131fe479a58SAl Viro 2132d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2133d6bb3e90SLinus Torvalds nd->last.name = name; 21345f4a6a69SAl Viro nd->last_type = type; 21355f4a6a69SAl Viro 2136d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2137d6bb3e90SLinus Torvalds if (!*name) 2138bdf6cbf1SAl Viro goto OK; 2139200e9ef7SLinus Torvalds /* 2140200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2141200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2142200e9ef7SLinus Torvalds */ 2143200e9ef7SLinus Torvalds do { 2144d6bb3e90SLinus Torvalds name++; 2145d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21468620c238SAl Viro if (unlikely(!*name)) { 21478620c238SAl Viro OK: 2148d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2149c108837eSAl Viro if (!depth) { 2150c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 21518620c238SAl Viro return 0; 2152c108837eSAl Viro } 21538620c238SAl Viro /* last component of nested symlink */ 2154d8d4611aSAl Viro name = nd->stack[--depth].name; 21558c4efe22SAl Viro link = walk_component(nd, 0); 21561c4ff1a8SAl Viro } else { 21571c4ff1a8SAl Viro /* not the last component */ 21588c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 21598620c238SAl Viro } 216092d27016SAl Viro if (unlikely(link)) { 216192d27016SAl Viro if (IS_ERR(link)) 216292d27016SAl Viro return PTR_ERR(link); 216392d27016SAl Viro /* a symlink to follow */ 2164d8d4611aSAl Viro nd->stack[depth++].name = name; 216592d27016SAl Viro name = link; 21669e18f10aSAl Viro continue; 216748c8b0c5SAl Viro } 216897242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 216997242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21704675ac39SAl Viro if (unlazy_walk(nd)) 217197242f99SAl Viro return -ECHILD; 217297242f99SAl Viro } 21733595e234SAl Viro return -ENOTDIR; 21745f4a6a69SAl Viro } 2175ce57dfc1SAl Viro } 217697242f99SAl Viro } 21771da177e4SLinus Torvalds 2178edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2179c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 218031e6b01fSNick Piggin { 2181740a1678SAleksa Sarai int error; 2182c8a53ee5SAl Viro const char *s = nd->name->name; 218331e6b01fSNick Piggin 2184c0eb027eSLinus Torvalds if (!*s) 2185c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2186edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2187edc2b1daSAl Viro rcu_read_lock(); 2188c0eb027eSLinus Torvalds 2189c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 219031e6b01fSNick Piggin nd->depth = 0; 2191ab87f9a5SAleksa Sarai 2192ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2193ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2194ab87f9a5SAleksa Sarai smp_rmb(); 2195ab87f9a5SAleksa Sarai 21965b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2197b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2198b18825a7SDavid Howells struct inode *inode = root->d_inode; 219993893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2200368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22015b6ca027SAl Viro nd->path = nd->root; 22025b6ca027SAl Viro nd->inode = inode; 22035b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2204ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22058f47a016SAl Viro nd->root_seq = nd->seq; 22065b6ca027SAl Viro } else { 22075b6ca027SAl Viro path_get(&nd->path); 22085b6ca027SAl Viro } 2209368ee9baSAl Viro return s; 22105b6ca027SAl Viro } 22115b6ca027SAl Viro 221231e6b01fSNick Piggin nd->root.mnt = NULL; 2213248fb5b9SAl Viro nd->path.mnt = NULL; 2214248fb5b9SAl Viro nd->path.dentry = NULL; 221531e6b01fSNick Piggin 22168db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22178db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2218740a1678SAleksa Sarai error = nd_jump_root(nd); 2219740a1678SAleksa Sarai if (unlikely(error)) 2220740a1678SAleksa Sarai return ERR_PTR(error); 2221ef55d917SAl Viro return s; 22228db52c7eSAleksa Sarai } 22238db52c7eSAleksa Sarai 22248db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22258db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2226e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 222731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2228c28cc364SNick Piggin unsigned seq; 222931e6b01fSNick Piggin 2230c28cc364SNick Piggin do { 2231c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 223231e6b01fSNick Piggin nd->path = fs->pwd; 2233ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2234c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2235c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2236e41f7d4eSAl Viro } else { 2237e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2238ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2239e41f7d4eSAl Viro } 224031e6b01fSNick Piggin } else { 2241582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2242c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 224331e6b01fSNick Piggin struct dentry *dentry; 224431e6b01fSNick Piggin 22452903ff01SAl Viro if (!f.file) 2246368ee9baSAl Viro return ERR_PTR(-EBADF); 224731e6b01fSNick Piggin 22482903ff01SAl Viro dentry = f.file->f_path.dentry; 224931e6b01fSNick Piggin 2250edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22512903ff01SAl Viro fdput(f); 2252368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2253f52e0c11SAl Viro } 22542903ff01SAl Viro 22552903ff01SAl Viro nd->path = f.file->f_path; 2256e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 225734a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 225834a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22595590ff0dSUlrich Drepper } else { 22602903ff01SAl Viro path_get(&nd->path); 226134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22621da177e4SLinus Torvalds } 226334a26b99SAl Viro fdput(f); 2264e41f7d4eSAl Viro } 22658db52c7eSAleksa Sarai 2266adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2267adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2268adb21d2bSAleksa Sarai nd->root = nd->path; 2269adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2270adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2271adb21d2bSAleksa Sarai } else { 2272adb21d2bSAleksa Sarai path_get(&nd->root); 2273adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2274adb21d2bSAleksa Sarai } 2275adb21d2bSAleksa Sarai } 2276adb21d2bSAleksa Sarai return s; 22779b4a9b14SAl Viro } 22789b4a9b14SAl Viro 22791ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 228095fa25d9SAl Viro { 2281bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2282bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2283bd92d7feSAl Viro 2284c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2285bd92d7feSAl Viro } 2286bd92d7feSAl Viro 22874f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 22884f757f3cSAl Viro { 2289c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2290db3c9adeSAl Viro dget(nd->path.dentry); 2291b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2292b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 22934f757f3cSAl Viro } 22944f757f3cSAl Viro 22959b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2296c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 22979b4a9b14SAl Viro { 2298c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2299bd92d7feSAl Viro int err; 230031e6b01fSNick Piggin 23019b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23024f757f3cSAl Viro err = handle_lookup_down(nd); 23035f336e72SAl Viro if (unlikely(err < 0)) 23045f336e72SAl Viro s = ERR_PTR(err); 23054f757f3cSAl Viro } 23064f757f3cSAl Viro 23071ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23081ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23091ccac622SAl Viro ; 23109f1fafeeSAl Viro if (!err) 23119f1fafeeSAl Viro err = complete_walk(nd); 2312bd92d7feSAl Viro 2313deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2314deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2315bd23a539SAl Viro err = -ENOTDIR; 2316161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2317161aff1dSAl Viro err = handle_lookup_down(nd); 2318161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2319161aff1dSAl Viro } 2320625b6d10SAl Viro if (!err) { 2321625b6d10SAl Viro *path = nd->path; 2322625b6d10SAl Viro nd->path.mnt = NULL; 2323625b6d10SAl Viro nd->path.dentry = NULL; 2324625b6d10SAl Viro } 2325deb106c6SAl Viro terminate_walk(nd); 2326bd92d7feSAl Viro return err; 232731e6b01fSNick Piggin } 232831e6b01fSNick Piggin 232931d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23309ad1aaa6SAl Viro struct path *path, struct path *root) 2331873f1eedSJeff Layton { 2332894bc8c4SAl Viro int retval; 23339883d185SAl Viro struct nameidata nd; 2334abc9f5beSAl Viro if (IS_ERR(name)) 2335abc9f5beSAl Viro return PTR_ERR(name); 23369ad1aaa6SAl Viro if (unlikely(root)) { 23379ad1aaa6SAl Viro nd.root = *root; 23389ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23399ad1aaa6SAl Viro } 23409883d185SAl Viro set_nameidata(&nd, dfd, name); 2341c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2342873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2343c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2344873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2345c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2346873f1eedSJeff Layton 2347873f1eedSJeff Layton if (likely(!retval)) 2348161aff1dSAl Viro audit_inode(name, path->dentry, 2349161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23509883d185SAl Viro restore_nameidata(); 2351e4bd1c1aSAl Viro putname(name); 2352873f1eedSJeff Layton return retval; 2353873f1eedSJeff Layton } 2354873f1eedSJeff Layton 23558bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2356c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2357391172c4SAl Viro struct path *parent) 23588bcb77faSAl Viro { 2359c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23609b5858e9SAl Viro int err = link_path_walk(s, nd); 23618bcb77faSAl Viro if (!err) 23628bcb77faSAl Viro err = complete_walk(nd); 2363391172c4SAl Viro if (!err) { 2364391172c4SAl Viro *parent = nd->path; 2365391172c4SAl Viro nd->path.mnt = NULL; 2366391172c4SAl Viro nd->path.dentry = NULL; 2367391172c4SAl Viro } 2368deb106c6SAl Viro terminate_walk(nd); 23698bcb77faSAl Viro return err; 23708bcb77faSAl Viro } 23718bcb77faSAl Viro 23725c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2373391172c4SAl Viro unsigned int flags, struct path *parent, 2374391172c4SAl Viro struct qstr *last, int *type) 23758bcb77faSAl Viro { 23768bcb77faSAl Viro int retval; 23779883d185SAl Viro struct nameidata nd; 23788bcb77faSAl Viro 23795c31b6ceSAl Viro if (IS_ERR(name)) 23805c31b6ceSAl Viro return name; 23819883d185SAl Viro set_nameidata(&nd, dfd, name); 2382c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 23838bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2384c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 23858bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2386c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2387391172c4SAl Viro if (likely(!retval)) { 2388391172c4SAl Viro *last = nd.last; 2389391172c4SAl Viro *type = nd.last_type; 2390c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 23915c31b6ceSAl Viro } else { 23925c31b6ceSAl Viro putname(name); 23935c31b6ceSAl Viro name = ERR_PTR(retval); 2394391172c4SAl Viro } 23959883d185SAl Viro restore_nameidata(); 23965c31b6ceSAl Viro return name; 23978bcb77faSAl Viro } 23988bcb77faSAl Viro 239979714f72SAl Viro /* does lookup, returns the object with parent locked */ 240079714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24015590ff0dSUlrich Drepper { 24025c31b6ceSAl Viro struct filename *filename; 24035c31b6ceSAl Viro struct dentry *d; 2404391172c4SAl Viro struct qstr last; 2405391172c4SAl Viro int type; 240651689104SPaul Moore 24075c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24085c31b6ceSAl Viro &last, &type); 240951689104SPaul Moore if (IS_ERR(filename)) 241051689104SPaul Moore return ERR_CAST(filename); 24115c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2412391172c4SAl Viro path_put(path); 24135c31b6ceSAl Viro putname(filename); 24145c31b6ceSAl Viro return ERR_PTR(-EINVAL); 241579714f72SAl Viro } 24165955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2417391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 241879714f72SAl Viro if (IS_ERR(d)) { 24195955102cSAl Viro inode_unlock(path->dentry->d_inode); 2420391172c4SAl Viro path_put(path); 242179714f72SAl Viro } 242251689104SPaul Moore putname(filename); 242379714f72SAl Viro return d; 24245590ff0dSUlrich Drepper } 24255590ff0dSUlrich Drepper 2426d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2427d1811465SAl Viro { 2428abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2429abc9f5beSAl Viro flags, path, NULL); 2430d1811465SAl Viro } 24314d359507SAl Viro EXPORT_SYMBOL(kern_path); 2432d1811465SAl Viro 243316f18200SJosef 'Jeff' Sipek /** 243416f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 243516f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 243616f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 243716f18200SJosef 'Jeff' Sipek * @name: pointer to file name 243816f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2439e0a01249SAl Viro * @path: pointer to struct path to fill 244016f18200SJosef 'Jeff' Sipek */ 244116f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 244216f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2443e0a01249SAl Viro struct path *path) 244416f18200SJosef 'Jeff' Sipek { 24459ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24469ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2447abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2448abc9f5beSAl Viro flags , path, &root); 244916f18200SJosef 'Jeff' Sipek } 24504d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 245116f18200SJosef 'Jeff' Sipek 24523c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24533c95f0dcSAl Viro int len, struct qstr *this) 24543c95f0dcSAl Viro { 24553c95f0dcSAl Viro this->name = name; 24563c95f0dcSAl Viro this->len = len; 24573c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24583c95f0dcSAl Viro if (!len) 24593c95f0dcSAl Viro return -EACCES; 24603c95f0dcSAl Viro 24613c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24623c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24633c95f0dcSAl Viro return -EACCES; 24643c95f0dcSAl Viro } 24653c95f0dcSAl Viro 24663c95f0dcSAl Viro while (len--) { 24673c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24683c95f0dcSAl Viro if (c == '/' || c == '\0') 24693c95f0dcSAl Viro return -EACCES; 24703c95f0dcSAl Viro } 24713c95f0dcSAl Viro /* 24723c95f0dcSAl Viro * See if the low-level filesystem might want 24733c95f0dcSAl Viro * to use its own hash.. 24743c95f0dcSAl Viro */ 24753c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 24763c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 24773c95f0dcSAl Viro if (err < 0) 24783c95f0dcSAl Viro return err; 24793c95f0dcSAl Viro } 24803c95f0dcSAl Viro 24813c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 24823c95f0dcSAl Viro } 24833c95f0dcSAl Viro 2484eead1911SChristoph Hellwig /** 24850da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 24860da0b7fdSDavid Howells * @name: pathname component to lookup 24870da0b7fdSDavid Howells * @base: base directory to lookup from 24880da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 24890da0b7fdSDavid Howells * 24900da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 24910da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 24920da0b7fdSDavid Howells * 24930da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 24940da0b7fdSDavid Howells * not be called by generic code. 24950da0b7fdSDavid Howells * 24960da0b7fdSDavid Howells * The caller must hold base->i_mutex. 24970da0b7fdSDavid Howells */ 24980da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 24990da0b7fdSDavid Howells { 25000da0b7fdSDavid Howells struct qstr this; 25010da0b7fdSDavid Howells int err; 25020da0b7fdSDavid Howells 25030da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25040da0b7fdSDavid Howells 25050da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25060da0b7fdSDavid Howells if (err) 25070da0b7fdSDavid Howells return ERR_PTR(err); 25080da0b7fdSDavid Howells 25090da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25100da0b7fdSDavid Howells } 25110da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25120da0b7fdSDavid Howells 25130da0b7fdSDavid Howells /** 2514a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2515eead1911SChristoph Hellwig * @name: pathname component to lookup 2516eead1911SChristoph Hellwig * @base: base directory to lookup from 2517eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2518eead1911SChristoph Hellwig * 2519a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25209e7543e9SAl Viro * not be called by generic code. 2521bbddca8eSNeilBrown * 2522bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2523eead1911SChristoph Hellwig */ 2524057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2525057f6c01SJames Morris { 25268613a209SAl Viro struct dentry *dentry; 2527057f6c01SJames Morris struct qstr this; 2528cda309deSMiklos Szeredi int err; 2529057f6c01SJames Morris 25305955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25312f9092e1SDavid Woodhouse 25323c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2533cda309deSMiklos Szeredi if (err) 2534cda309deSMiklos Szeredi return ERR_PTR(err); 2535cda309deSMiklos Szeredi 25368613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25378613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2538057f6c01SJames Morris } 25394d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2540057f6c01SJames Morris 2541bbddca8eSNeilBrown /** 2542bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2543bbddca8eSNeilBrown * @name: pathname component to lookup 2544bbddca8eSNeilBrown * @base: base directory to lookup from 2545bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2546bbddca8eSNeilBrown * 2547bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2548bbddca8eSNeilBrown * not be called by generic code. 2549bbddca8eSNeilBrown * 2550bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2551bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2552bbddca8eSNeilBrown */ 2553bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2554bbddca8eSNeilBrown struct dentry *base, int len) 2555bbddca8eSNeilBrown { 2556bbddca8eSNeilBrown struct qstr this; 2557bbddca8eSNeilBrown int err; 255820d00ee8SLinus Torvalds struct dentry *ret; 2559bbddca8eSNeilBrown 25603c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2561bbddca8eSNeilBrown if (err) 2562bbddca8eSNeilBrown return ERR_PTR(err); 2563bbddca8eSNeilBrown 256420d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 256520d00ee8SLinus Torvalds if (!ret) 256620d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 256720d00ee8SLinus Torvalds return ret; 2568bbddca8eSNeilBrown } 2569bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2570bbddca8eSNeilBrown 25716c2d4798SAl Viro /* 25726c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 25736c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 25746c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 25756c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 25766c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 25776c2d4798SAl Viro * this one avoids such problems. 25786c2d4798SAl Viro */ 25796c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 25806c2d4798SAl Viro struct dentry *base, int len) 25816c2d4798SAl Viro { 25826c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 25832fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 25846c2d4798SAl Viro dput(ret); 25856c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 25866c2d4798SAl Viro } 25876c2d4798SAl Viro return ret; 25886c2d4798SAl Viro } 25896c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 25906c2d4798SAl Viro 2591eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2592eedf265aSEric W. Biederman int path_pts(struct path *path) 2593eedf265aSEric W. Biederman { 2594eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2595eedf265aSEric W. Biederman * the input path. 2596eedf265aSEric W. Biederman */ 2597a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2598a6a7eb76SAl Viro struct dentry *child; 2599eedf265aSEric W. Biederman struct qstr this; 2600eedf265aSEric W. Biederman 2601a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2602a6a7eb76SAl Viro dput(parent); 260363b27720SAl Viro return -ENOENT; 2604a6a7eb76SAl Viro } 260563b27720SAl Viro dput(path->dentry); 260663b27720SAl Viro path->dentry = parent; 2607eedf265aSEric W. Biederman this.name = "pts"; 2608eedf265aSEric W. Biederman this.len = 3; 2609eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2610eedf265aSEric W. Biederman if (!child) 2611eedf265aSEric W. Biederman return -ENOENT; 2612eedf265aSEric W. Biederman 2613eedf265aSEric W. Biederman path->dentry = child; 2614eedf265aSEric W. Biederman dput(parent); 2615eedf265aSEric W. Biederman follow_mount(path); 2616eedf265aSEric W. Biederman return 0; 2617eedf265aSEric W. Biederman } 2618eedf265aSEric W. Biederman #endif 2619eedf265aSEric W. Biederman 26201fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26211fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26221da177e4SLinus Torvalds { 2623abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2624abc9f5beSAl Viro flags, path, NULL); 26251da177e4SLinus Torvalds } 2626b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26271fa1e7f6SAndy Whitcroft 2628cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26291da177e4SLinus Torvalds { 26308e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2631da9592edSDavid Howells 26328e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26331da177e4SLinus Torvalds return 0; 26348e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26351da177e4SLinus Torvalds return 0; 263623adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26371da177e4SLinus Torvalds } 2638cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26391da177e4SLinus Torvalds 26401da177e4SLinus Torvalds /* 26411da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26421da177e4SLinus Torvalds * whether the type of victim is right. 26431da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26441da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26451da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26461da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26471da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26481da177e4SLinus Torvalds * a. be owner of dir, or 26491da177e4SLinus Torvalds * b. be owner of victim, or 26501da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26511da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26521da177e4SLinus Torvalds * links pointing to it. 26530bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26540bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26550bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26560bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 26570bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 26581da177e4SLinus Torvalds * nfs_async_unlink(). 26591da177e4SLinus Torvalds */ 2660b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26611da177e4SLinus Torvalds { 266263afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26631da177e4SLinus Torvalds int error; 26641da177e4SLinus Torvalds 2665b18825a7SDavid Howells if (d_is_negative(victim)) 26661da177e4SLinus Torvalds return -ENOENT; 2667b18825a7SDavid Howells BUG_ON(!inode); 26681da177e4SLinus Torvalds 26691da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2670593d1ce8SEric W. Biederman 2671593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2672593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2673593d1ce8SEric W. Biederman return -EOVERFLOW; 2674593d1ce8SEric W. Biederman 26754fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 26761da177e4SLinus Torvalds 2677f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 26781da177e4SLinus Torvalds if (error) 26791da177e4SLinus Torvalds return error; 26801da177e4SLinus Torvalds if (IS_APPEND(dir)) 26811da177e4SLinus Torvalds return -EPERM; 2682b18825a7SDavid Howells 2683b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 26840bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 26851da177e4SLinus Torvalds return -EPERM; 26861da177e4SLinus Torvalds if (isdir) { 268744b1d530SMiklos Szeredi if (!d_is_dir(victim)) 26881da177e4SLinus Torvalds return -ENOTDIR; 26891da177e4SLinus Torvalds if (IS_ROOT(victim)) 26901da177e4SLinus Torvalds return -EBUSY; 269144b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 26921da177e4SLinus Torvalds return -EISDIR; 26931da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 26941da177e4SLinus Torvalds return -ENOENT; 26951da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 26961da177e4SLinus Torvalds return -EBUSY; 26971da177e4SLinus Torvalds return 0; 26981da177e4SLinus Torvalds } 26991da177e4SLinus Torvalds 27001da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27011da177e4SLinus Torvalds * dir. 27021da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27031da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27041da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2705036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2706036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2707036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27081da177e4SLinus Torvalds */ 2709a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27101da177e4SLinus Torvalds { 2711036d5236SEric W. Biederman struct user_namespace *s_user_ns; 271214e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27131da177e4SLinus Torvalds if (child->d_inode) 27141da177e4SLinus Torvalds return -EEXIST; 27151da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27161da177e4SLinus Torvalds return -ENOENT; 2717036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2718036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2719036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2720036d5236SEric W. Biederman return -EOVERFLOW; 2721f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27221da177e4SLinus Torvalds } 27231da177e4SLinus Torvalds 27241da177e4SLinus Torvalds /* 27251da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27261da177e4SLinus Torvalds */ 27271da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27281da177e4SLinus Torvalds { 27291da177e4SLinus Torvalds struct dentry *p; 27301da177e4SLinus Torvalds 27311da177e4SLinus Torvalds if (p1 == p2) { 27325955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27331da177e4SLinus Torvalds return NULL; 27341da177e4SLinus Torvalds } 27351da177e4SLinus Torvalds 2736fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27371da177e4SLinus Torvalds 2738e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2739e2761a11SOGAWA Hirofumi if (p) { 27405955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27415955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27421da177e4SLinus Torvalds return p; 27431da177e4SLinus Torvalds } 27441da177e4SLinus Torvalds 2745e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2746e2761a11SOGAWA Hirofumi if (p) { 27475955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27485955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27491da177e4SLinus Torvalds return p; 27501da177e4SLinus Torvalds } 27511da177e4SLinus Torvalds 27525955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27535955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27541da177e4SLinus Torvalds return NULL; 27551da177e4SLinus Torvalds } 27564d359507SAl Viro EXPORT_SYMBOL(lock_rename); 27571da177e4SLinus Torvalds 27581da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 27591da177e4SLinus Torvalds { 27605955102cSAl Viro inode_unlock(p1->d_inode); 27611da177e4SLinus Torvalds if (p1 != p2) { 27625955102cSAl Viro inode_unlock(p2->d_inode); 2763fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 27641da177e4SLinus Torvalds } 27651da177e4SLinus Torvalds } 27664d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 27671da177e4SLinus Torvalds 27684acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2769312b63fbSAl Viro bool want_excl) 27701da177e4SLinus Torvalds { 2771a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27721da177e4SLinus Torvalds if (error) 27731da177e4SLinus Torvalds return error; 27741da177e4SLinus Torvalds 2775acfa4380SAl Viro if (!dir->i_op->create) 27761da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 27771da177e4SLinus Torvalds mode &= S_IALLUGO; 27781da177e4SLinus Torvalds mode |= S_IFREG; 27791da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 27801da177e4SLinus Torvalds if (error) 27811da177e4SLinus Torvalds return error; 2782312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2783a74574aaSStephen Smalley if (!error) 2784f38aa942SAmy Griffis fsnotify_create(dir, dentry); 27851da177e4SLinus Torvalds return error; 27861da177e4SLinus Torvalds } 27874d359507SAl Viro EXPORT_SYMBOL(vfs_create); 27881da177e4SLinus Torvalds 27898e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 27908e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 27918e6c848eSAl Viro void *arg) 27928e6c848eSAl Viro { 27938e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 27948e6c848eSAl Viro int error = may_create(dir, dentry); 27958e6c848eSAl Viro if (error) 27968e6c848eSAl Viro return error; 27978e6c848eSAl Viro 27988e6c848eSAl Viro mode &= S_IALLUGO; 27998e6c848eSAl Viro mode |= S_IFREG; 28008e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28018e6c848eSAl Viro if (error) 28028e6c848eSAl Viro return error; 28038e6c848eSAl Viro error = f(dentry, mode, arg); 28048e6c848eSAl Viro if (!error) 28058e6c848eSAl Viro fsnotify_create(dir, dentry); 28068e6c848eSAl Viro return error; 28078e6c848eSAl Viro } 28088e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28098e6c848eSAl Viro 2810a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2811a2982cc9SEric W. Biederman { 2812a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2813a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2814a2982cc9SEric W. Biederman } 2815a2982cc9SEric W. Biederman 2816f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28171da177e4SLinus Torvalds { 28183fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28191da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28201da177e4SLinus Torvalds int error; 28211da177e4SLinus Torvalds 28221da177e4SLinus Torvalds if (!inode) 28231da177e4SLinus Torvalds return -ENOENT; 28241da177e4SLinus Torvalds 2825c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2826c8fe8f30SChristoph Hellwig case S_IFLNK: 28271da177e4SLinus Torvalds return -ELOOP; 2828c8fe8f30SChristoph Hellwig case S_IFDIR: 2829c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28301da177e4SLinus Torvalds return -EISDIR; 2831c8fe8f30SChristoph Hellwig break; 2832c8fe8f30SChristoph Hellwig case S_IFBLK: 2833c8fe8f30SChristoph Hellwig case S_IFCHR: 2834a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28351da177e4SLinus Torvalds return -EACCES; 2836c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2837c8fe8f30SChristoph Hellwig case S_IFIFO: 2838c8fe8f30SChristoph Hellwig case S_IFSOCK: 28391da177e4SLinus Torvalds flag &= ~O_TRUNC; 2840c8fe8f30SChristoph Hellwig break; 28414a3fd211SDave Hansen } 2842b41572e9SDave Hansen 284362fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2844b41572e9SDave Hansen if (error) 2845b41572e9SDave Hansen return error; 28466146f0d5SMimi Zohar 28471da177e4SLinus Torvalds /* 28481da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28491da177e4SLinus Torvalds */ 28501da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28518737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28527715b521SAl Viro return -EPERM; 28531da177e4SLinus Torvalds if (flag & O_TRUNC) 28547715b521SAl Viro return -EPERM; 28551da177e4SLinus Torvalds } 28561da177e4SLinus Torvalds 28571da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28582e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28597715b521SAl Viro return -EPERM; 28601da177e4SLinus Torvalds 2861f3c7691eSJ. Bruce Fields return 0; 28627715b521SAl Viro } 28637715b521SAl Viro 2864e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28657715b521SAl Viro { 2866f0bb5aafSAl Viro const struct path *path = &filp->f_path; 28677715b521SAl Viro struct inode *inode = path->dentry->d_inode; 28687715b521SAl Viro int error = get_write_access(inode); 28691da177e4SLinus Torvalds if (error) 28707715b521SAl Viro return error; 28711da177e4SLinus Torvalds /* 28721da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 28731da177e4SLinus Torvalds */ 2874d7a06983SJeff Layton error = locks_verify_locked(filp); 2875be6d3e56SKentaro Takeda if (!error) 2876ea0d3ab2STetsuo Handa error = security_path_truncate(path); 28771da177e4SLinus Torvalds if (!error) { 28787715b521SAl Viro error = do_truncate(path->dentry, 0, 2879d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2880e1181ee6SJeff Layton filp); 28811da177e4SLinus Torvalds } 28821da177e4SLinus Torvalds put_write_access(inode); 2883acd0c935SMimi Zohar return error; 28841da177e4SLinus Torvalds } 28851da177e4SLinus Torvalds 2886d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2887d57999e1SDave Hansen { 28888a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 28898a5e929dSAl Viro flag--; 2890d57999e1SDave Hansen return flag; 2891d57999e1SDave Hansen } 2892d57999e1SDave Hansen 2893d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2894d18e9008SMiklos Szeredi { 28951328c727SSeth Forshee struct user_namespace *s_user_ns; 2896d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2897d18e9008SMiklos Szeredi if (error) 2898d18e9008SMiklos Szeredi return error; 2899d18e9008SMiklos Szeredi 29001328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29011328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29021328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29031328c727SSeth Forshee return -EOVERFLOW; 29041328c727SSeth Forshee 2905d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2906d18e9008SMiklos Szeredi if (error) 2907d18e9008SMiklos Szeredi return error; 2908d18e9008SMiklos Szeredi 2909d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2910d18e9008SMiklos Szeredi } 2911d18e9008SMiklos Szeredi 29121acf0af9SDavid Howells /* 29131acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29141acf0af9SDavid Howells * dentry. 29151acf0af9SDavid Howells * 29161acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29171acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29181acf0af9SDavid Howells * 291900a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 292000a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 292100a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29221acf0af9SDavid Howells * 29231acf0af9SDavid Howells * Returns an error code otherwise. 29241acf0af9SDavid Howells */ 2925239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2926239eb983SAl Viro struct file *file, 2927015c3bbcSMiklos Szeredi const struct open_flags *op, 29283ec2eef1SAl Viro int open_flag, umode_t mode) 2929d18e9008SMiklos Szeredi { 2930d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2931d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2932d18e9008SMiklos Szeredi int error; 2933d18e9008SMiklos Szeredi 2934384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2935d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2936d18e9008SMiklos Szeredi 2937d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2938d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2939d18e9008SMiklos Szeredi 294030d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 294130d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29420fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 294344907d79SAl Viro open_to_namei_flags(open_flag), mode); 29446fbd0714SAl Viro d_lookup_done(dentry); 2945384f26e2SAl Viro if (!error) { 294664e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 29476fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 29486fb968cdSAl Viro dput(dentry); 29496fb968cdSAl Viro dentry = dget(file->f_path.dentry); 29506fb968cdSAl Viro } 29517be219b4SAl Viro if (file->f_mode & FMODE_CREATED) 295203da633aSAl Viro fsnotify_create(dir, dentry); 295364e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2954116cc022SMiklos Szeredi error = -EIO; 2955384f26e2SAl Viro } else { 2956d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2957d18e9008SMiklos Szeredi dput(dentry); 2958d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 295910c64ceaSAl Viro } 296073a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 2961d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2962239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 2963a01e718fSAl Viro error = -ENOENT; 2964d18e9008SMiklos Szeredi } 2965d18e9008SMiklos Szeredi } 2966239eb983SAl Viro if (error) { 2967d18e9008SMiklos Szeredi dput(dentry); 2968239eb983SAl Viro dentry = ERR_PTR(error); 2969239eb983SAl Viro } 2970239eb983SAl Viro return dentry; 2971d18e9008SMiklos Szeredi } 2972d18e9008SMiklos Szeredi 297331e6b01fSNick Piggin /* 29741acf0af9SDavid Howells * Look up and maybe create and open the last component. 2975d58ffd35SMiklos Szeredi * 297600a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 2977d58ffd35SMiklos Szeredi * 297800a07c15SAl Viro * Returns 0 on success, that is, if 297900a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 298000a07c15SAl Viro * the file was not completely opened at this time, though lookups and 298100a07c15SAl Viro * creations were performed. 298200a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 298300a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 298400a07c15SAl Viro * hadn't been specified. 29851acf0af9SDavid Howells * 298600a07c15SAl Viro * An error code is returned on failure. 2987d58ffd35SMiklos Szeredi */ 2988da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 2989d58ffd35SMiklos Szeredi const struct open_flags *op, 29903ec2eef1SAl Viro bool got_write) 2991d58ffd35SMiklos Szeredi { 2992d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 299354ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 29941643b43fSAl Viro int open_flag = op->open_flag; 2995d58ffd35SMiklos Szeredi struct dentry *dentry; 29961643b43fSAl Viro int error, create_error = 0; 29971643b43fSAl Viro umode_t mode = op->mode; 29986fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 2999d58ffd35SMiklos Szeredi 3000ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3001da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3002d58ffd35SMiklos Szeredi 300373a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30046fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30056fbd0714SAl Viro for (;;) { 30066fbd0714SAl Viro if (!dentry) { 30076fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3008d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3009da5ebf5aSAl Viro return dentry; 30106fbd0714SAl Viro } 30116fbd0714SAl Viro if (d_in_lookup(dentry)) 30126fbd0714SAl Viro break; 3013d58ffd35SMiklos Szeredi 30146fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30156fbd0714SAl Viro if (likely(error > 0)) 30166fbd0714SAl Viro break; 30176fbd0714SAl Viro if (error) 30186fbd0714SAl Viro goto out_dput; 30196fbd0714SAl Viro d_invalidate(dentry); 30206fbd0714SAl Viro dput(dentry); 30216fbd0714SAl Viro dentry = NULL; 30226fbd0714SAl Viro } 30236fbd0714SAl Viro if (dentry->d_inode) { 3024d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3025da5ebf5aSAl Viro return dentry; 30266c51e513SAl Viro } 3027d18e9008SMiklos Szeredi 30281643b43fSAl Viro /* 30291643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30301643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30311643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30321643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30331643b43fSAl Viro * 30341643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30351643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30361643b43fSAl Viro */ 30371643b43fSAl Viro if (open_flag & O_CREAT) { 30381643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30391643b43fSAl Viro mode &= ~current_umask(); 30401643b43fSAl Viro if (unlikely(!got_write)) { 30411643b43fSAl Viro create_error = -EROFS; 30421643b43fSAl Viro open_flag &= ~O_CREAT; 30431643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30441643b43fSAl Viro goto no_open; 30451643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30461643b43fSAl Viro } else { 30471643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30481643b43fSAl Viro if (create_error) { 30491643b43fSAl Viro open_flag &= ~O_CREAT; 30501643b43fSAl Viro if (open_flag & O_EXCL) 30511643b43fSAl Viro goto no_open; 30521643b43fSAl Viro } 30531643b43fSAl Viro } 30541643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30551643b43fSAl Viro unlikely(!got_write)) { 30561643b43fSAl Viro /* 30571643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30581643b43fSAl Viro * back to lookup + open 30591643b43fSAl Viro */ 30601643b43fSAl Viro goto no_open; 3061d18e9008SMiklos Szeredi } 3062d18e9008SMiklos Szeredi 30631643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3064239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3065da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3066da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3067da5ebf5aSAl Viro return dentry; 3068239eb983SAl Viro } 306954ef4872SMiklos Szeredi 30701643b43fSAl Viro no_open: 30716fbd0714SAl Viro if (d_in_lookup(dentry)) { 307212fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 307312fa5e24SAl Viro nd->flags); 30746fbd0714SAl Viro d_lookup_done(dentry); 307512fa5e24SAl Viro if (unlikely(res)) { 307612fa5e24SAl Viro if (IS_ERR(res)) { 307712fa5e24SAl Viro error = PTR_ERR(res); 307812fa5e24SAl Viro goto out_dput; 307912fa5e24SAl Viro } 308012fa5e24SAl Viro dput(dentry); 308112fa5e24SAl Viro dentry = res; 308212fa5e24SAl Viro } 308354ef4872SMiklos Szeredi } 308454ef4872SMiklos Szeredi 3085d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 30861643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 308773a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3088ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3089ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3090ce8644fcSAl Viro error = -EACCES; 3091d58ffd35SMiklos Szeredi goto out_dput; 309264894cf8SAl Viro } 3093ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 30941643b43fSAl Viro open_flag & O_EXCL); 3095d58ffd35SMiklos Szeredi if (error) 3096d58ffd35SMiklos Szeredi goto out_dput; 3097ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3098d58ffd35SMiklos Szeredi } 30991643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31001643b43fSAl Viro error = create_error; 3101d58ffd35SMiklos Szeredi goto out_dput; 3102d58ffd35SMiklos Szeredi } 3103da5ebf5aSAl Viro return dentry; 3104d58ffd35SMiklos Szeredi 3105d58ffd35SMiklos Szeredi out_dput: 3106d58ffd35SMiklos Szeredi dput(dentry); 3107da5ebf5aSAl Viro return ERR_PTR(error); 3108d58ffd35SMiklos Szeredi } 3109d58ffd35SMiklos Szeredi 3110c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 31113ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3112fb1cc555SAl Viro { 3113a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3114ca344a89SAl Viro int open_flag = op->open_flag; 311564894cf8SAl Viro bool got_write = false; 3116254cf582SAl Viro unsigned seq; 3117a1eb3315SMiklos Szeredi struct inode *inode; 3118da5ebf5aSAl Viro struct dentry *dentry; 3119b0417d2cSAl Viro const char *res; 312016c2cd71SAl Viro int error; 3121fb1cc555SAl Viro 3122c3e380b0SAl Viro nd->flags |= op->intent; 3123c3e380b0SAl Viro 3124bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 312556676ec3SAl Viro if (nd->depth) 312656676ec3SAl Viro put_link(nd); 3127fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 3128c981a482SAl Viro if (likely(!error)) 3129c981a482SAl Viro error = complete_walk(nd); 31301ccac622SAl Viro return ERR_PTR(error); 31311f36f774SAl Viro } 3132a2c36b45SAl Viro 3133ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3134fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3135fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3136fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 313720e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 313820e34357SAl Viro if (IS_ERR(dentry)) 31391ccac622SAl Viro return ERR_CAST(dentry); 314020e34357SAl Viro if (likely(dentry)) 314171574865SMiklos Szeredi goto finish_lookup; 314271574865SMiklos Szeredi 31436583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3144b6183df7SMiklos Szeredi } else { 3145fe2d35ffSAl Viro /* create side of things */ 3146a3fbbde7SAl Viro /* 3147b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3148b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3149b6183df7SMiklos Szeredi * about to look up 3150a3fbbde7SAl Viro */ 31519f1fafeeSAl Viro error = complete_walk(nd); 3152c981a482SAl Viro if (unlikely(error)) 31531ccac622SAl Viro return ERR_PTR(error); 3154fe2d35ffSAl Viro 3155c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 31561f36f774SAl Viro /* trailing slashes? */ 3157deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 31581ccac622SAl Viro return ERR_PTR(-EISDIR); 3159b6183df7SMiklos Szeredi } 31601f36f774SAl Viro 31619cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 316264894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 316364894cf8SAl Viro if (!error) 316464894cf8SAl Viro got_write = true; 316564894cf8SAl Viro /* 316664894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 316764894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 316864894cf8SAl Viro * dropping this one anyway. 316964894cf8SAl Viro */ 317064894cf8SAl Viro } 31719cf843e3SAl Viro if (open_flag & O_CREAT) 31725955102cSAl Viro inode_lock(dir->d_inode); 31739cf843e3SAl Viro else 31749cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3175da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 31769cf843e3SAl Viro if (open_flag & O_CREAT) 31775955102cSAl Viro inode_unlock(dir->d_inode); 31789cf843e3SAl Viro else 31799cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3180fb1cc555SAl Viro 3181c981a482SAl Viro if (got_write) 318259e96e65SAl Viro mnt_drop_write(nd->path.mnt); 31836c0d46c4SAl Viro 318459e96e65SAl Viro if (IS_ERR(dentry)) 318559e96e65SAl Viro return ERR_CAST(dentry); 318659e96e65SAl Viro 3187973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3188e73cabffSAl Viro dput(nd->path.dentry); 3189e73cabffSAl Viro nd->path.dentry = dentry; 3190c981a482SAl Viro return NULL; 3191fb1cc555SAl Viro } 3192fb1cc555SAl Viro 319320e34357SAl Viro finish_lookup: 319456676ec3SAl Viro if (nd->depth) 319556676ec3SAl Viro put_link(nd); 31968c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3197b0417d2cSAl Viro if (unlikely(res)) { 31981ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3199b0417d2cSAl Viro return res; 32001ccac622SAl Viro } 320131d1726dSAl Viro 320231d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 320331d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32041ccac622SAl Viro return ERR_PTR(-EEXIST); 320531d1726dSAl Viro } 3206c981a482SAl Viro 32078f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3208c981a482SAl Viro return ERR_PTR(complete_walk(nd)); 3209c981a482SAl Viro } 3210c981a482SAl Viro 3211c981a482SAl Viro /* 3212c981a482SAl Viro * Handle the last step of open() 3213c981a482SAl Viro */ 3214c981a482SAl Viro static const char *do_last(struct nameidata *nd, 3215c981a482SAl Viro struct file *file, const struct open_flags *op) 3216c981a482SAl Viro { 3217c981a482SAl Viro kuid_t dir_uid = nd->inode->i_uid; 3218c981a482SAl Viro umode_t dir_mode = nd->inode->i_mode; 3219c981a482SAl Viro int open_flag = op->open_flag; 3220c981a482SAl Viro bool do_truncate; 3221c981a482SAl Viro int acc_mode; 3222c981a482SAl Viro const char *link; 3223c981a482SAl Viro int error; 3224c981a482SAl Viro 3225c981a482SAl Viro link = open_last_lookups(nd, file, op); 3226c981a482SAl Viro if (unlikely(link)) 3227c981a482SAl Viro return link; 3228c981a482SAl Viro 3229973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 323076ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 323130aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 323230aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 323359e96e65SAl Viro return ERR_PTR(-EISDIR); 3234d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 323530aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 323630aba665SSalvatore Mesoraca if (unlikely(error)) 323759e96e65SAl Viro return ERR_PTR(error); 323830aba665SSalvatore Mesoraca } 323944b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 324059e96e65SAl Viro return ERR_PTR(-ENOTDIR); 32416c0d46c4SAl Viro 32428795e7d4SAl Viro do_truncate = false; 32438795e7d4SAl Viro acc_mode = op->acc_mode; 32445a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32455a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32465a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32475a2d3eddSAl Viro acc_mode = 0; 32488795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32490f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32500f9d1a10SAl Viro if (error) 325159e96e65SAl Viro return ERR_PTR(error); 32528795e7d4SAl Viro do_truncate = true; 32530f9d1a10SAl Viro } 3254bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 32558795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3256ae2bb293SAl Viro error = vfs_open(&nd->path, file); 32578795e7d4SAl Viro if (!error) 32586035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 32598795e7d4SAl Viro if (!error && do_truncate) 32602675a4ebSAl Viro error = handle_truncate(file); 3261c80567c8SAl Viro if (unlikely(error > 0)) { 3262c80567c8SAl Viro WARN_ON(1); 3263c80567c8SAl Viro error = -EINVAL; 3264c80567c8SAl Viro } 32658795e7d4SAl Viro if (do_truncate) 32660f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 32671ccac622SAl Viro return ERR_PTR(error); 3268fb1cc555SAl Viro } 3269fb1cc555SAl Viro 3270af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3271af7bd4dcSAmir Goldstein { 3272af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3273af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3274af7bd4dcSAmir Goldstein struct inode *inode; 3275af7bd4dcSAmir Goldstein int error; 3276af7bd4dcSAmir Goldstein 3277af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3278af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3279af7bd4dcSAmir Goldstein if (error) 3280af7bd4dcSAmir Goldstein goto out_err; 3281af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3282af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3283af7bd4dcSAmir Goldstein goto out_err; 3284af7bd4dcSAmir Goldstein error = -ENOMEM; 3285cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3286af7bd4dcSAmir Goldstein if (unlikely(!child)) 3287af7bd4dcSAmir Goldstein goto out_err; 3288af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3289af7bd4dcSAmir Goldstein if (error) 3290af7bd4dcSAmir Goldstein goto out_err; 3291af7bd4dcSAmir Goldstein error = -ENOENT; 3292af7bd4dcSAmir Goldstein inode = child->d_inode; 3293af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3294af7bd4dcSAmir Goldstein goto out_err; 3295af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3296af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3297af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3298af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3299af7bd4dcSAmir Goldstein } 3300fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3301af7bd4dcSAmir Goldstein return child; 3302af7bd4dcSAmir Goldstein 3303af7bd4dcSAmir Goldstein out_err: 3304af7bd4dcSAmir Goldstein dput(child); 3305af7bd4dcSAmir Goldstein return ERR_PTR(error); 3306af7bd4dcSAmir Goldstein } 3307af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3308af7bd4dcSAmir Goldstein 3309c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 331060545d0dSAl Viro const struct open_flags *op, 33113ec2eef1SAl Viro struct file *file) 331260545d0dSAl Viro { 3313625b6d10SAl Viro struct dentry *child; 3314625b6d10SAl Viro struct path path; 3315c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 331660545d0dSAl Viro if (unlikely(error)) 331760545d0dSAl Viro return error; 3318625b6d10SAl Viro error = mnt_want_write(path.mnt); 331960545d0dSAl Viro if (unlikely(error)) 332060545d0dSAl Viro goto out; 3321af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3322af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3323684e73beSHirofumi Nakagawa if (IS_ERR(child)) 332460545d0dSAl Viro goto out2; 3325625b6d10SAl Viro dput(path.dentry); 3326625b6d10SAl Viro path.dentry = child; 3327c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 332869a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 332962fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 333060545d0dSAl Viro if (error) 333160545d0dSAl Viro goto out2; 3332625b6d10SAl Viro file->f_path.mnt = path.mnt; 3333be12af3eSAl Viro error = finish_open(file, child, NULL); 333460545d0dSAl Viro out2: 3335625b6d10SAl Viro mnt_drop_write(path.mnt); 333660545d0dSAl Viro out: 3337625b6d10SAl Viro path_put(&path); 333860545d0dSAl Viro return error; 333960545d0dSAl Viro } 334060545d0dSAl Viro 33416ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33426ac08709SAl Viro { 33436ac08709SAl Viro struct path path; 33446ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33456ac08709SAl Viro if (!error) { 33466ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3347ae2bb293SAl Viro error = vfs_open(&path, file); 33486ac08709SAl Viro path_put(&path); 33496ac08709SAl Viro } 33506ac08709SAl Viro return error; 33516ac08709SAl Viro } 33526ac08709SAl Viro 3353c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3354c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33551da177e4SLinus Torvalds { 335630d90494SAl Viro struct file *file; 335713aab428SAl Viro int error; 335831e6b01fSNick Piggin 3359ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 33601afc99beSAl Viro if (IS_ERR(file)) 33611afc99beSAl Viro return file; 336231e6b01fSNick Piggin 3363bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 33643ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 33655f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 33666ac08709SAl Viro error = do_o_path(nd, flags, file); 33675f336e72SAl Viro } else { 33685f336e72SAl Viro const char *s = path_init(nd, flags); 33693bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33701ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 33711ccac622SAl Viro ; 3372deb106c6SAl Viro terminate_walk(nd); 33735f336e72SAl Viro } 33747c1c01ecSAl Viro if (likely(!error)) { 3375aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 33767c1c01ecSAl Viro return file; 33777c1c01ecSAl Viro WARN_ON(1); 33787c1c01ecSAl Viro error = -EINVAL; 3379015c3bbcSMiklos Szeredi } 33807c1c01ecSAl Viro fput(file); 33812675a4ebSAl Viro if (error == -EOPENSTALE) { 33822675a4ebSAl Viro if (flags & LOOKUP_RCU) 33832675a4ebSAl Viro error = -ECHILD; 33842675a4ebSAl Viro else 33852675a4ebSAl Viro error = -ESTALE; 33862675a4ebSAl Viro } 33877c1c01ecSAl Viro return ERR_PTR(error); 3388de459215SKirill Korotaev } 33891da177e4SLinus Torvalds 3390669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3391f9652e10SAl Viro const struct open_flags *op) 339213aab428SAl Viro { 33939883d185SAl Viro struct nameidata nd; 3394f9652e10SAl Viro int flags = op->lookup_flags; 339513aab428SAl Viro struct file *filp; 339613aab428SAl Viro 33979883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3398c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 339913aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3400c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 340113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3402c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34039883d185SAl Viro restore_nameidata(); 340413aab428SAl Viro return filp; 340513aab428SAl Viro } 340613aab428SAl Viro 340773d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3408f9652e10SAl Viro const char *name, const struct open_flags *op) 340973d049a4SAl Viro { 34109883d185SAl Viro struct nameidata nd; 341173d049a4SAl Viro struct file *file; 341251689104SPaul Moore struct filename *filename; 3413f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 341473d049a4SAl Viro 341573d049a4SAl Viro nd.root.mnt = mnt; 341673d049a4SAl Viro nd.root.dentry = dentry; 341773d049a4SAl Viro 3418b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 341973d049a4SAl Viro return ERR_PTR(-ELOOP); 342073d049a4SAl Viro 342151689104SPaul Moore filename = getname_kernel(name); 3422a1c83681SViresh Kumar if (IS_ERR(filename)) 342351689104SPaul Moore return ERR_CAST(filename); 342451689104SPaul Moore 34259883d185SAl Viro set_nameidata(&nd, -1, filename); 3426c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 342773d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3428c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 342973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3430c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34319883d185SAl Viro restore_nameidata(); 343251689104SPaul Moore putname(filename); 343373d049a4SAl Viro return file; 343473d049a4SAl Viro } 343573d049a4SAl Viro 3436fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34371ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34381da177e4SLinus Torvalds { 3439c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3440391172c4SAl Viro struct qstr last; 3441391172c4SAl Viro int type; 3442c30dabfeSJan Kara int err2; 34431ac12b4bSJeff Layton int error; 34441ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34451ac12b4bSJeff Layton 34461ac12b4bSJeff Layton /* 34471ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34481ac12b4bSJeff Layton * other flags passed in are ignored! 34491ac12b4bSJeff Layton */ 34501ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34511ac12b4bSJeff Layton 34525c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34535c31b6ceSAl Viro if (IS_ERR(name)) 34545c31b6ceSAl Viro return ERR_CAST(name); 34551da177e4SLinus Torvalds 3456c663e5d8SChristoph Hellwig /* 3457c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3458c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3459c663e5d8SChristoph Hellwig */ 34605c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3461ed75e95dSAl Viro goto out; 3462c663e5d8SChristoph Hellwig 3463c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3464391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3465c663e5d8SChristoph Hellwig /* 3466c663e5d8SChristoph Hellwig * Do the final lookup. 3467c663e5d8SChristoph Hellwig */ 3468391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 34695955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3470391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34711da177e4SLinus Torvalds if (IS_ERR(dentry)) 3472a8104a9fSAl Viro goto unlock; 3473c663e5d8SChristoph Hellwig 3474a8104a9fSAl Viro error = -EEXIST; 3475b18825a7SDavid Howells if (d_is_positive(dentry)) 3476a8104a9fSAl Viro goto fail; 3477b18825a7SDavid Howells 3478c663e5d8SChristoph Hellwig /* 3479c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3480c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3481c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3482c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3483c663e5d8SChristoph Hellwig */ 3484391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3485a8104a9fSAl Viro error = -ENOENT; 3486ed75e95dSAl Viro goto fail; 3487e9baf6e5SAl Viro } 3488c30dabfeSJan Kara if (unlikely(err2)) { 3489c30dabfeSJan Kara error = err2; 3490a8104a9fSAl Viro goto fail; 3491c30dabfeSJan Kara } 3492181c37b6SAl Viro putname(name); 3493e9baf6e5SAl Viro return dentry; 34941da177e4SLinus Torvalds fail: 3495a8104a9fSAl Viro dput(dentry); 3496a8104a9fSAl Viro dentry = ERR_PTR(error); 3497a8104a9fSAl Viro unlock: 34985955102cSAl Viro inode_unlock(path->dentry->d_inode); 3499c30dabfeSJan Kara if (!err2) 3500391172c4SAl Viro mnt_drop_write(path->mnt); 3501ed75e95dSAl Viro out: 3502391172c4SAl Viro path_put(path); 3503181c37b6SAl Viro putname(name); 3504ed75e95dSAl Viro return dentry; 3505dae6ad8fSAl Viro } 3506fa14a0b8SAl Viro 3507fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3508fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3509fa14a0b8SAl Viro { 3510181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3511181c37b6SAl Viro path, lookup_flags); 3512fa14a0b8SAl Viro } 3513dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3514dae6ad8fSAl Viro 3515921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3516921a1650SAl Viro { 3517921a1650SAl Viro dput(dentry); 35185955102cSAl Viro inode_unlock(path->dentry->d_inode); 3519a8104a9fSAl Viro mnt_drop_write(path->mnt); 3520921a1650SAl Viro path_put(path); 3521921a1650SAl Viro } 3522921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3523921a1650SAl Viro 3524520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35251ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3526dae6ad8fSAl Viro { 3527181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3528dae6ad8fSAl Viro } 3529dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3530dae6ad8fSAl Viro 35311a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35321da177e4SLinus Torvalds { 3533a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35341da177e4SLinus Torvalds 35351da177e4SLinus Torvalds if (error) 35361da177e4SLinus Torvalds return error; 35371da177e4SLinus Torvalds 353894f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35391da177e4SLinus Torvalds return -EPERM; 35401da177e4SLinus Torvalds 3541acfa4380SAl Viro if (!dir->i_op->mknod) 35421da177e4SLinus Torvalds return -EPERM; 35431da177e4SLinus Torvalds 354408ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 354508ce5f16SSerge E. Hallyn if (error) 354608ce5f16SSerge E. Hallyn return error; 354708ce5f16SSerge E. Hallyn 35481da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35491da177e4SLinus Torvalds if (error) 35501da177e4SLinus Torvalds return error; 35511da177e4SLinus Torvalds 35521da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3553a74574aaSStephen Smalley if (!error) 3554f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35551da177e4SLinus Torvalds return error; 35561da177e4SLinus Torvalds } 35574d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35581da177e4SLinus Torvalds 3559f69aac00SAl Viro static int may_mknod(umode_t mode) 3560463c3197SDave Hansen { 3561463c3197SDave Hansen switch (mode & S_IFMT) { 3562463c3197SDave Hansen case S_IFREG: 3563463c3197SDave Hansen case S_IFCHR: 3564463c3197SDave Hansen case S_IFBLK: 3565463c3197SDave Hansen case S_IFIFO: 3566463c3197SDave Hansen case S_IFSOCK: 3567463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3568463c3197SDave Hansen return 0; 3569463c3197SDave Hansen case S_IFDIR: 3570463c3197SDave Hansen return -EPERM; 3571463c3197SDave Hansen default: 3572463c3197SDave Hansen return -EINVAL; 3573463c3197SDave Hansen } 3574463c3197SDave Hansen } 3575463c3197SDave Hansen 357687c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 357787c4e192SDominik Brodowski unsigned int dev) 35781da177e4SLinus Torvalds { 35791da177e4SLinus Torvalds struct dentry *dentry; 3580dae6ad8fSAl Viro struct path path; 3581dae6ad8fSAl Viro int error; 3582972567f1SJeff Layton unsigned int lookup_flags = 0; 35831da177e4SLinus Torvalds 35848e4bfca1SAl Viro error = may_mknod(mode); 35858e4bfca1SAl Viro if (error) 35868e4bfca1SAl Viro return error; 3587972567f1SJeff Layton retry: 3588972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3589dae6ad8fSAl Viro if (IS_ERR(dentry)) 3590dae6ad8fSAl Viro return PTR_ERR(dentry); 35912ad94ae6SAl Viro 3592dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3593ce3b0f8dSAl Viro mode &= ~current_umask(); 3594dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3595be6d3e56SKentaro Takeda if (error) 3596a8104a9fSAl Viro goto out; 35971da177e4SLinus Torvalds switch (mode & S_IFMT) { 35981da177e4SLinus Torvalds case 0: case S_IFREG: 3599312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 360005d1a717SMimi Zohar if (!error) 360105d1a717SMimi Zohar ima_post_path_mknod(dentry); 36021da177e4SLinus Torvalds break; 36031da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3604dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36051da177e4SLinus Torvalds new_decode_dev(dev)); 36061da177e4SLinus Torvalds break; 36071da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3608dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36091da177e4SLinus Torvalds break; 36101da177e4SLinus Torvalds } 3611a8104a9fSAl Viro out: 3612921a1650SAl Viro done_path_create(&path, dentry); 3613972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3614972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3615972567f1SJeff Layton goto retry; 3616972567f1SJeff Layton } 36171da177e4SLinus Torvalds return error; 36181da177e4SLinus Torvalds } 36191da177e4SLinus Torvalds 362087c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 362187c4e192SDominik Brodowski unsigned int, dev) 362287c4e192SDominik Brodowski { 362387c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 362487c4e192SDominik Brodowski } 362587c4e192SDominik Brodowski 36268208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36275590ff0dSUlrich Drepper { 362887c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36295590ff0dSUlrich Drepper } 36305590ff0dSUlrich Drepper 363118bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36321da177e4SLinus Torvalds { 3633a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36348de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36351da177e4SLinus Torvalds 36361da177e4SLinus Torvalds if (error) 36371da177e4SLinus Torvalds return error; 36381da177e4SLinus Torvalds 3639acfa4380SAl Viro if (!dir->i_op->mkdir) 36401da177e4SLinus Torvalds return -EPERM; 36411da177e4SLinus Torvalds 36421da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36431da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36441da177e4SLinus Torvalds if (error) 36451da177e4SLinus Torvalds return error; 36461da177e4SLinus Torvalds 36478de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36488de52778SAl Viro return -EMLINK; 36498de52778SAl Viro 36501da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3651a74574aaSStephen Smalley if (!error) 3652f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36531da177e4SLinus Torvalds return error; 36541da177e4SLinus Torvalds } 36554d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36561da177e4SLinus Torvalds 36570101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 36581da177e4SLinus Torvalds { 36596902d925SDave Hansen struct dentry *dentry; 3660dae6ad8fSAl Viro struct path path; 3661dae6ad8fSAl Viro int error; 3662b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36631da177e4SLinus Torvalds 3664b76d8b82SJeff Layton retry: 3665b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36666902d925SDave Hansen if (IS_ERR(dentry)) 3667dae6ad8fSAl Viro return PTR_ERR(dentry); 36686902d925SDave Hansen 3669dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3670ce3b0f8dSAl Viro mode &= ~current_umask(); 3671dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3672a8104a9fSAl Viro if (!error) 3673dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3674921a1650SAl Viro done_path_create(&path, dentry); 3675b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3676b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3677b76d8b82SJeff Layton goto retry; 3678b76d8b82SJeff Layton } 36791da177e4SLinus Torvalds return error; 36801da177e4SLinus Torvalds } 36811da177e4SLinus Torvalds 36820101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 36830101db7aSDominik Brodowski { 36840101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 36850101db7aSDominik Brodowski } 36860101db7aSDominik Brodowski 3687a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 36885590ff0dSUlrich Drepper { 36890101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 36905590ff0dSUlrich Drepper } 36915590ff0dSUlrich Drepper 36921da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36931da177e4SLinus Torvalds { 36941da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36951da177e4SLinus Torvalds 36961da177e4SLinus Torvalds if (error) 36971da177e4SLinus Torvalds return error; 36981da177e4SLinus Torvalds 3699acfa4380SAl Viro if (!dir->i_op->rmdir) 37001da177e4SLinus Torvalds return -EPERM; 37011da177e4SLinus Torvalds 37021d2ef590SAl Viro dget(dentry); 37035955102cSAl Viro inode_lock(dentry->d_inode); 3704912dbc15SSage Weil 37051da177e4SLinus Torvalds error = -EBUSY; 37067af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3707912dbc15SSage Weil goto out; 3708912dbc15SSage Weil 37091da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3710912dbc15SSage Weil if (error) 3711912dbc15SSage Weil goto out; 3712912dbc15SSage Weil 37131da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3714912dbc15SSage Weil if (error) 3715912dbc15SSage Weil goto out; 3716912dbc15SSage Weil 37178767712fSAl Viro shrink_dcache_parent(dentry); 37181da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3719d83c49f3SAl Viro dont_mount(dentry); 37208ed936b5SEric W. Biederman detach_mounts(dentry); 3721116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37221da177e4SLinus Torvalds 3723912dbc15SSage Weil out: 37245955102cSAl Viro inode_unlock(dentry->d_inode); 37251d2ef590SAl Viro dput(dentry); 3726912dbc15SSage Weil if (!error) 3727912dbc15SSage Weil d_delete(dentry); 37281da177e4SLinus Torvalds return error; 37291da177e4SLinus Torvalds } 37304d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37311da177e4SLinus Torvalds 3732f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37331da177e4SLinus Torvalds { 37341da177e4SLinus Torvalds int error = 0; 373591a27b2aSJeff Layton struct filename *name; 37361da177e4SLinus Torvalds struct dentry *dentry; 3737f5beed75SAl Viro struct path path; 3738f5beed75SAl Viro struct qstr last; 3739f5beed75SAl Viro int type; 3740c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3741c6ee9206SJeff Layton retry: 3742c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3743c1d4dd27SAl Viro &path, &last, &type); 374491a27b2aSJeff Layton if (IS_ERR(name)) 374591a27b2aSJeff Layton return PTR_ERR(name); 37461da177e4SLinus Torvalds 3747f5beed75SAl Viro switch (type) { 37481da177e4SLinus Torvalds case LAST_DOTDOT: 37491da177e4SLinus Torvalds error = -ENOTEMPTY; 37501da177e4SLinus Torvalds goto exit1; 37511da177e4SLinus Torvalds case LAST_DOT: 37521da177e4SLinus Torvalds error = -EINVAL; 37531da177e4SLinus Torvalds goto exit1; 37541da177e4SLinus Torvalds case LAST_ROOT: 37551da177e4SLinus Torvalds error = -EBUSY; 37561da177e4SLinus Torvalds goto exit1; 37571da177e4SLinus Torvalds } 37580612d9fbSOGAWA Hirofumi 3759f5beed75SAl Viro error = mnt_want_write(path.mnt); 3760c30dabfeSJan Kara if (error) 3761c30dabfeSJan Kara goto exit1; 37620612d9fbSOGAWA Hirofumi 37635955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3764f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37651da177e4SLinus Torvalds error = PTR_ERR(dentry); 37666902d925SDave Hansen if (IS_ERR(dentry)) 37676902d925SDave Hansen goto exit2; 3768e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3769e6bc45d6STheodore Ts'o error = -ENOENT; 3770e6bc45d6STheodore Ts'o goto exit3; 3771e6bc45d6STheodore Ts'o } 3772f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3773be6d3e56SKentaro Takeda if (error) 3774c30dabfeSJan Kara goto exit3; 3775f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37760622753bSDave Hansen exit3: 37771da177e4SLinus Torvalds dput(dentry); 37786902d925SDave Hansen exit2: 37795955102cSAl Viro inode_unlock(path.dentry->d_inode); 3780f5beed75SAl Viro mnt_drop_write(path.mnt); 37811da177e4SLinus Torvalds exit1: 3782f5beed75SAl Viro path_put(&path); 37831da177e4SLinus Torvalds putname(name); 3784c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3785c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3786c6ee9206SJeff Layton goto retry; 3787c6ee9206SJeff Layton } 37881da177e4SLinus Torvalds return error; 37891da177e4SLinus Torvalds } 37901da177e4SLinus Torvalds 37913cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37925590ff0dSUlrich Drepper { 37935590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37945590ff0dSUlrich Drepper } 37955590ff0dSUlrich Drepper 3796b21996e3SJ. Bruce Fields /** 3797b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3798b21996e3SJ. Bruce Fields * @dir: parent directory 3799b21996e3SJ. Bruce Fields * @dentry: victim 3800b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3801b21996e3SJ. Bruce Fields * 3802b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3803b21996e3SJ. Bruce Fields * 3804b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3805b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3806b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3807b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3808b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3809b21996e3SJ. Bruce Fields * 3810b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3811b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3812b21996e3SJ. Bruce Fields * to be NFS exported. 3813b21996e3SJ. Bruce Fields */ 3814b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38151da177e4SLinus Torvalds { 38169accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38171da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38181da177e4SLinus Torvalds 38191da177e4SLinus Torvalds if (error) 38201da177e4SLinus Torvalds return error; 38211da177e4SLinus Torvalds 3822acfa4380SAl Viro if (!dir->i_op->unlink) 38231da177e4SLinus Torvalds return -EPERM; 38241da177e4SLinus Torvalds 38255955102cSAl Viro inode_lock(target); 38268ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38271da177e4SLinus Torvalds error = -EBUSY; 38281da177e4SLinus Torvalds else { 38291da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3830bec1052eSAl Viro if (!error) { 38315a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38325a14696cSJ. Bruce Fields if (error) 3833b21996e3SJ. Bruce Fields goto out; 38341da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38358ed936b5SEric W. Biederman if (!error) { 3836d83c49f3SAl Viro dont_mount(dentry); 38378ed936b5SEric W. Biederman detach_mounts(dentry); 3838116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38398ed936b5SEric W. Biederman } 3840bec1052eSAl Viro } 38411da177e4SLinus Torvalds } 3842b21996e3SJ. Bruce Fields out: 38435955102cSAl Viro inode_unlock(target); 38441da177e4SLinus Torvalds 38451da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38461da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38479accbb97SJ. Bruce Fields fsnotify_link_count(target); 38481da177e4SLinus Torvalds d_delete(dentry); 38491da177e4SLinus Torvalds } 38500eeca283SRobert Love 38511da177e4SLinus Torvalds return error; 38521da177e4SLinus Torvalds } 38534d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38541da177e4SLinus Torvalds 38551da177e4SLinus Torvalds /* 38561da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38571b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38581da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38591da177e4SLinus Torvalds * while waiting on the I/O. 38601da177e4SLinus Torvalds */ 3861da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 38621da177e4SLinus Torvalds { 38632ad94ae6SAl Viro int error; 38641da177e4SLinus Torvalds struct dentry *dentry; 3865f5beed75SAl Viro struct path path; 3866f5beed75SAl Viro struct qstr last; 3867f5beed75SAl Viro int type; 38681da177e4SLinus Torvalds struct inode *inode = NULL; 3869b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38705d18f813SJeff Layton unsigned int lookup_flags = 0; 38715d18f813SJeff Layton retry: 3872da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 387391a27b2aSJeff Layton if (IS_ERR(name)) 387491a27b2aSJeff Layton return PTR_ERR(name); 38752ad94ae6SAl Viro 38761da177e4SLinus Torvalds error = -EISDIR; 3877f5beed75SAl Viro if (type != LAST_NORM) 38781da177e4SLinus Torvalds goto exit1; 38790612d9fbSOGAWA Hirofumi 3880f5beed75SAl Viro error = mnt_want_write(path.mnt); 3881c30dabfeSJan Kara if (error) 3882c30dabfeSJan Kara goto exit1; 3883b21996e3SJ. Bruce Fields retry_deleg: 38845955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3885f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38861da177e4SLinus Torvalds error = PTR_ERR(dentry); 38871da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38881da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3889f5beed75SAl Viro if (last.name[last.len]) 389050338b88STörök Edwin goto slashes; 38911da177e4SLinus Torvalds inode = dentry->d_inode; 3892b18825a7SDavid Howells if (d_is_negative(dentry)) 3893e6bc45d6STheodore Ts'o goto slashes; 38947de9c6eeSAl Viro ihold(inode); 3895f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3896be6d3e56SKentaro Takeda if (error) 3897c30dabfeSJan Kara goto exit2; 3898f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38991da177e4SLinus Torvalds exit2: 39001da177e4SLinus Torvalds dput(dentry); 39011da177e4SLinus Torvalds } 39025955102cSAl Viro inode_unlock(path.dentry->d_inode); 39031da177e4SLinus Torvalds if (inode) 39041da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3905b21996e3SJ. Bruce Fields inode = NULL; 3906b21996e3SJ. Bruce Fields if (delegated_inode) { 39075a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3908b21996e3SJ. Bruce Fields if (!error) 3909b21996e3SJ. Bruce Fields goto retry_deleg; 3910b21996e3SJ. Bruce Fields } 3911f5beed75SAl Viro mnt_drop_write(path.mnt); 39121da177e4SLinus Torvalds exit1: 3913f5beed75SAl Viro path_put(&path); 39145d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39155d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39165d18f813SJeff Layton inode = NULL; 39175d18f813SJeff Layton goto retry; 39185d18f813SJeff Layton } 3919da2f1362SChristoph Hellwig putname(name); 39201da177e4SLinus Torvalds return error; 39211da177e4SLinus Torvalds 39221da177e4SLinus Torvalds slashes: 3923b18825a7SDavid Howells if (d_is_negative(dentry)) 3924b18825a7SDavid Howells error = -ENOENT; 392544b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3926b18825a7SDavid Howells error = -EISDIR; 3927b18825a7SDavid Howells else 3928b18825a7SDavid Howells error = -ENOTDIR; 39291da177e4SLinus Torvalds goto exit2; 39301da177e4SLinus Torvalds } 39311da177e4SLinus Torvalds 39322e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39335590ff0dSUlrich Drepper { 39345590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39355590ff0dSUlrich Drepper return -EINVAL; 39365590ff0dSUlrich Drepper 39375590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39385590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39395590ff0dSUlrich Drepper 3940da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39415590ff0dSUlrich Drepper } 39425590ff0dSUlrich Drepper 39433480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39445590ff0dSUlrich Drepper { 3945da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39465590ff0dSUlrich Drepper } 39475590ff0dSUlrich Drepper 3948db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39491da177e4SLinus Torvalds { 3950a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39511da177e4SLinus Torvalds 39521da177e4SLinus Torvalds if (error) 39531da177e4SLinus Torvalds return error; 39541da177e4SLinus Torvalds 3955acfa4380SAl Viro if (!dir->i_op->symlink) 39561da177e4SLinus Torvalds return -EPERM; 39571da177e4SLinus Torvalds 39581da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39591da177e4SLinus Torvalds if (error) 39601da177e4SLinus Torvalds return error; 39611da177e4SLinus Torvalds 39621da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3963a74574aaSStephen Smalley if (!error) 3964f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39651da177e4SLinus Torvalds return error; 39661da177e4SLinus Torvalds } 39674d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39681da177e4SLinus Torvalds 3969b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 3970b724e846SDominik Brodowski const char __user *newname) 39711da177e4SLinus Torvalds { 39722ad94ae6SAl Viro int error; 397391a27b2aSJeff Layton struct filename *from; 39746902d925SDave Hansen struct dentry *dentry; 3975dae6ad8fSAl Viro struct path path; 3976f46d3567SJeff Layton unsigned int lookup_flags = 0; 39771da177e4SLinus Torvalds 39781da177e4SLinus Torvalds from = getname(oldname); 39791da177e4SLinus Torvalds if (IS_ERR(from)) 39801da177e4SLinus Torvalds return PTR_ERR(from); 3981f46d3567SJeff Layton retry: 3982f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39831da177e4SLinus Torvalds error = PTR_ERR(dentry); 39846902d925SDave Hansen if (IS_ERR(dentry)) 3985dae6ad8fSAl Viro goto out_putname; 39866902d925SDave Hansen 398791a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3988a8104a9fSAl Viro if (!error) 398991a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3990921a1650SAl Viro done_path_create(&path, dentry); 3991f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3992f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3993f46d3567SJeff Layton goto retry; 3994f46d3567SJeff Layton } 39956902d925SDave Hansen out_putname: 39961da177e4SLinus Torvalds putname(from); 39971da177e4SLinus Torvalds return error; 39981da177e4SLinus Torvalds } 39991da177e4SLinus Torvalds 4000b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4001b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4002b724e846SDominik Brodowski { 4003b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4004b724e846SDominik Brodowski } 4005b724e846SDominik Brodowski 40063480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40075590ff0dSUlrich Drepper { 4008b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40095590ff0dSUlrich Drepper } 40105590ff0dSUlrich Drepper 4011146a8595SJ. Bruce Fields /** 4012146a8595SJ. Bruce Fields * vfs_link - create a new link 4013146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4014146a8595SJ. Bruce Fields * @dir: new parent 4015146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4016146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4017146a8595SJ. Bruce Fields * 4018146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4019146a8595SJ. Bruce Fields * 4020146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4021146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4022146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4023146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4024146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4025146a8595SJ. Bruce Fields * 4026146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4027146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4028146a8595SJ. Bruce Fields * to be NFS exported. 4029146a8595SJ. Bruce Fields */ 4030146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40311da177e4SLinus Torvalds { 40321da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40338de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40341da177e4SLinus Torvalds int error; 40351da177e4SLinus Torvalds 40361da177e4SLinus Torvalds if (!inode) 40371da177e4SLinus Torvalds return -ENOENT; 40381da177e4SLinus Torvalds 4039a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40401da177e4SLinus Torvalds if (error) 40411da177e4SLinus Torvalds return error; 40421da177e4SLinus Torvalds 40431da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40441da177e4SLinus Torvalds return -EXDEV; 40451da177e4SLinus Torvalds 40461da177e4SLinus Torvalds /* 40471da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40481da177e4SLinus Torvalds */ 40491da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40501da177e4SLinus Torvalds return -EPERM; 40510bd23d09SEric W. Biederman /* 40520bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 40530bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 40540bd23d09SEric W. Biederman * the vfs. 40550bd23d09SEric W. Biederman */ 40560bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 40570bd23d09SEric W. Biederman return -EPERM; 4058acfa4380SAl Viro if (!dir->i_op->link) 40591da177e4SLinus Torvalds return -EPERM; 40607e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40611da177e4SLinus Torvalds return -EPERM; 40621da177e4SLinus Torvalds 40631da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40641da177e4SLinus Torvalds if (error) 40651da177e4SLinus Torvalds return error; 40661da177e4SLinus Torvalds 40675955102cSAl Viro inode_lock(inode); 4068aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4069f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4070aae8a97dSAneesh Kumar K.V error = -ENOENT; 40718de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40728de52778SAl Viro error = -EMLINK; 4073146a8595SJ. Bruce Fields else { 4074146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4075146a8595SJ. Bruce Fields if (!error) 40761da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4077146a8595SJ. Bruce Fields } 4078f4e0c30cSAl Viro 4079f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4080f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4081f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4082f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4083f4e0c30cSAl Viro } 40845955102cSAl Viro inode_unlock(inode); 4085e31e14ecSStephen Smalley if (!error) 40867e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 40871da177e4SLinus Torvalds return error; 40881da177e4SLinus Torvalds } 40894d359507SAl Viro EXPORT_SYMBOL(vfs_link); 40901da177e4SLinus Torvalds 40911da177e4SLinus Torvalds /* 40921da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 40931da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40941da177e4SLinus Torvalds * newname. --KAB 40951da177e4SLinus Torvalds * 40961da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40971da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40981da177e4SLinus Torvalds * and other special files. --ADM 40991da177e4SLinus Torvalds */ 410046ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 410146ea89ebSDominik Brodowski const char __user *newname, int flags) 41021da177e4SLinus Torvalds { 41031da177e4SLinus Torvalds struct dentry *new_dentry; 4104dae6ad8fSAl Viro struct path old_path, new_path; 4105146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 410611a7b371SAneesh Kumar K.V int how = 0; 41071da177e4SLinus Torvalds int error; 41081da177e4SLinus Torvalds 410911a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4110c04030e1SUlrich Drepper return -EINVAL; 411111a7b371SAneesh Kumar K.V /* 4112f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4113f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4114f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 411511a7b371SAneesh Kumar K.V */ 4116f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4117f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4118f0cc6ffbSLinus Torvalds return -ENOENT; 411911a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4120f0cc6ffbSLinus Torvalds } 4121c04030e1SUlrich Drepper 412211a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 412311a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4124442e31caSJeff Layton retry: 412511a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41261da177e4SLinus Torvalds if (error) 41272ad94ae6SAl Viro return error; 41282ad94ae6SAl Viro 4129442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4130442e31caSJeff Layton (how & LOOKUP_REVAL)); 41311da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41326902d925SDave Hansen if (IS_ERR(new_dentry)) 4133dae6ad8fSAl Viro goto out; 4134dae6ad8fSAl Viro 4135dae6ad8fSAl Viro error = -EXDEV; 4136dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4137dae6ad8fSAl Viro goto out_dput; 4138800179c9SKees Cook error = may_linkat(&old_path); 4139800179c9SKees Cook if (unlikely(error)) 4140800179c9SKees Cook goto out_dput; 4141dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4142be6d3e56SKentaro Takeda if (error) 4143a8104a9fSAl Viro goto out_dput; 4144146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 414575c3f29dSDave Hansen out_dput: 4146921a1650SAl Viro done_path_create(&new_path, new_dentry); 4147146a8595SJ. Bruce Fields if (delegated_inode) { 4148146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4149d22e6338SOleg Drokin if (!error) { 4150d22e6338SOleg Drokin path_put(&old_path); 4151146a8595SJ. Bruce Fields goto retry; 4152146a8595SJ. Bruce Fields } 4153d22e6338SOleg Drokin } 4154442e31caSJeff Layton if (retry_estale(error, how)) { 4155d22e6338SOleg Drokin path_put(&old_path); 4156442e31caSJeff Layton how |= LOOKUP_REVAL; 4157442e31caSJeff Layton goto retry; 4158442e31caSJeff Layton } 41591da177e4SLinus Torvalds out: 41602d8f3038SAl Viro path_put(&old_path); 41611da177e4SLinus Torvalds 41621da177e4SLinus Torvalds return error; 41631da177e4SLinus Torvalds } 41641da177e4SLinus Torvalds 416546ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 416646ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 416746ea89ebSDominik Brodowski { 416846ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 416946ea89ebSDominik Brodowski } 417046ea89ebSDominik Brodowski 41713480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41725590ff0dSUlrich Drepper { 417346ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41745590ff0dSUlrich Drepper } 41755590ff0dSUlrich Drepper 4176bc27027aSMiklos Szeredi /** 4177bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4178bc27027aSMiklos Szeredi * @old_dir: parent of source 4179bc27027aSMiklos Szeredi * @old_dentry: source 4180bc27027aSMiklos Szeredi * @new_dir: parent of destination 4181bc27027aSMiklos Szeredi * @new_dentry: destination 4182bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4183520c8b16SMiklos Szeredi * @flags: rename flags 4184bc27027aSMiklos Szeredi * 4185bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4186bc27027aSMiklos Szeredi * 4187bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4188bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4189bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4190bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4191bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4192bc27027aSMiklos Szeredi * so. 4193bc27027aSMiklos Szeredi * 4194bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4195bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4196bc27027aSMiklos Szeredi * to be NFS exported. 4197bc27027aSMiklos Szeredi * 41981da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 41991da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42001da177e4SLinus Torvalds * Problems: 42010117d427SMauro Carvalho Chehab * 4202d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42031da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42041da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4205a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42061da177e4SLinus Torvalds * story. 42076cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42086cedba89SJ. Bruce Fields * and source (if it is not a directory). 42091b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42101da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42111da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4212a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42131da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42141da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42151da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4216a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42171da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42181da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42191da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4220e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42211b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42221da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4223c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42241da177e4SLinus Torvalds * locking]. 42251da177e4SLinus Torvalds */ 42261da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42278e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4228520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42291da177e4SLinus Torvalds { 42301da177e4SLinus Torvalds int error; 4231bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4232bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4233bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4234da1ce067SMiklos Szeredi bool new_is_dir = false; 4235da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 423649d31c2fSAl Viro struct name_snapshot old_name; 42371da177e4SLinus Torvalds 42388d3e2936SMiklos Szeredi if (source == target) 42391da177e4SLinus Torvalds return 0; 42401da177e4SLinus Torvalds 42411da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42421da177e4SLinus Torvalds if (error) 42431da177e4SLinus Torvalds return error; 42441da177e4SLinus Torvalds 4245da1ce067SMiklos Szeredi if (!target) { 4246a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4247da1ce067SMiklos Szeredi } else { 4248da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4249da1ce067SMiklos Szeredi 4250da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42511da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4252da1ce067SMiklos Szeredi else 4253da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4254da1ce067SMiklos Szeredi } 42551da177e4SLinus Torvalds if (error) 42561da177e4SLinus Torvalds return error; 42571da177e4SLinus Torvalds 42582773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 42591da177e4SLinus Torvalds return -EPERM; 42601da177e4SLinus Torvalds 4261bc27027aSMiklos Szeredi /* 4262bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4263bc27027aSMiklos Szeredi * we'll need to flip '..'. 4264bc27027aSMiklos Szeredi */ 4265da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4266da1ce067SMiklos Szeredi if (is_dir) { 4267bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4268bc27027aSMiklos Szeredi if (error) 4269bc27027aSMiklos Szeredi return error; 4270bc27027aSMiklos Szeredi } 4271da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4272da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4273da1ce067SMiklos Szeredi if (error) 4274da1ce067SMiklos Szeredi return error; 4275da1ce067SMiklos Szeredi } 4276da1ce067SMiklos Szeredi } 42770eeca283SRobert Love 42780b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 42790b3974ebSMiklos Szeredi flags); 4280bc27027aSMiklos Szeredi if (error) 4281bc27027aSMiklos Szeredi return error; 4282bc27027aSMiklos Szeredi 428349d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4284bc27027aSMiklos Szeredi dget(new_dentry); 4285da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4286bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4287bc27027aSMiklos Szeredi else if (target) 42885955102cSAl Viro inode_lock(target); 4289bc27027aSMiklos Szeredi 4290bc27027aSMiklos Szeredi error = -EBUSY; 42917af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4292bc27027aSMiklos Szeredi goto out; 4293bc27027aSMiklos Szeredi 4294da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4295bc27027aSMiklos Szeredi error = -EMLINK; 4296da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4297bc27027aSMiklos Szeredi goto out; 4298da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4299da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4300da1ce067SMiklos Szeredi goto out; 4301da1ce067SMiklos Szeredi } 4302da1ce067SMiklos Szeredi if (!is_dir) { 4303bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4304bc27027aSMiklos Szeredi if (error) 4305bc27027aSMiklos Szeredi goto out; 4306da1ce067SMiklos Szeredi } 4307da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4308bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4309bc27027aSMiklos Szeredi if (error) 4310bc27027aSMiklos Szeredi goto out; 4311bc27027aSMiklos Szeredi } 4312520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4313520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4314bc27027aSMiklos Szeredi if (error) 4315bc27027aSMiklos Szeredi goto out; 4316bc27027aSMiklos Szeredi 4317da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43188767712fSAl Viro if (is_dir) { 43198767712fSAl Viro shrink_dcache_parent(new_dentry); 4320bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43218767712fSAl Viro } 4322bc27027aSMiklos Szeredi dont_mount(new_dentry); 43238ed936b5SEric W. Biederman detach_mounts(new_dentry); 4324bc27027aSMiklos Szeredi } 4325da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4326da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4327bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4328da1ce067SMiklos Szeredi else 4329da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4330da1ce067SMiklos Szeredi } 4331bc27027aSMiklos Szeredi out: 4332da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4333bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4334bc27027aSMiklos Szeredi else if (target) 43355955102cSAl Viro inode_unlock(target); 4336bc27027aSMiklos Szeredi dput(new_dentry); 4337da1ce067SMiklos Szeredi if (!error) { 4338f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4339da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4340da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4341f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4342da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4343da1ce067SMiklos Szeredi } 4344da1ce067SMiklos Szeredi } 434549d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 43460eeca283SRobert Love 43471da177e4SLinus Torvalds return error; 43481da177e4SLinus Torvalds } 43494d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43501da177e4SLinus Torvalds 4351ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4352ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 43531da177e4SLinus Torvalds { 43541da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43551da177e4SLinus Torvalds struct dentry *trap; 4356f5beed75SAl Viro struct path old_path, new_path; 4357f5beed75SAl Viro struct qstr old_last, new_last; 4358f5beed75SAl Viro int old_type, new_type; 43598e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 436091a27b2aSJeff Layton struct filename *from; 436191a27b2aSJeff Layton struct filename *to; 4362f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4363c6a94284SJeff Layton bool should_retry = false; 43642ad94ae6SAl Viro int error; 4365520c8b16SMiklos Szeredi 43660d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4367da1ce067SMiklos Szeredi return -EINVAL; 4368da1ce067SMiklos Szeredi 43690d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43700d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4371520c8b16SMiklos Szeredi return -EINVAL; 4372520c8b16SMiklos Szeredi 43730d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43740d7a8555SMiklos Szeredi return -EPERM; 43750d7a8555SMiklos Szeredi 4376f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4377f5beed75SAl Viro target_flags = 0; 4378f5beed75SAl Viro 4379c6a94284SJeff Layton retry: 4380c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4381c1d4dd27SAl Viro &old_path, &old_last, &old_type); 438291a27b2aSJeff Layton if (IS_ERR(from)) { 438391a27b2aSJeff Layton error = PTR_ERR(from); 43841da177e4SLinus Torvalds goto exit; 438591a27b2aSJeff Layton } 43861da177e4SLinus Torvalds 4387c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4388c1d4dd27SAl Viro &new_path, &new_last, &new_type); 438991a27b2aSJeff Layton if (IS_ERR(to)) { 439091a27b2aSJeff Layton error = PTR_ERR(to); 43911da177e4SLinus Torvalds goto exit1; 439291a27b2aSJeff Layton } 43931da177e4SLinus Torvalds 43941da177e4SLinus Torvalds error = -EXDEV; 4395f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43961da177e4SLinus Torvalds goto exit2; 43971da177e4SLinus Torvalds 43981da177e4SLinus Torvalds error = -EBUSY; 4399f5beed75SAl Viro if (old_type != LAST_NORM) 44001da177e4SLinus Torvalds goto exit2; 44011da177e4SLinus Torvalds 44020a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44030a7c3937SMiklos Szeredi error = -EEXIST; 4404f5beed75SAl Viro if (new_type != LAST_NORM) 44051da177e4SLinus Torvalds goto exit2; 44061da177e4SLinus Torvalds 4407f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4408c30dabfeSJan Kara if (error) 4409c30dabfeSJan Kara goto exit2; 4410c30dabfeSJan Kara 44118e6d782cSJ. Bruce Fields retry_deleg: 4412f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44131da177e4SLinus Torvalds 4414f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44151da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44161da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44171da177e4SLinus Torvalds goto exit3; 44181da177e4SLinus Torvalds /* source must exist */ 44191da177e4SLinus Torvalds error = -ENOENT; 4420b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44211da177e4SLinus Torvalds goto exit4; 4422f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44231da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44241da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44251da177e4SLinus Torvalds goto exit4; 44260a7c3937SMiklos Szeredi error = -EEXIST; 44270a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44280a7c3937SMiklos Szeredi goto exit5; 4429da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4430da1ce067SMiklos Szeredi error = -ENOENT; 4431da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4432da1ce067SMiklos Szeredi goto exit5; 4433da1ce067SMiklos Szeredi 4434da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4435da1ce067SMiklos Szeredi error = -ENOTDIR; 4436f5beed75SAl Viro if (new_last.name[new_last.len]) 4437da1ce067SMiklos Szeredi goto exit5; 4438da1ce067SMiklos Szeredi } 4439da1ce067SMiklos Szeredi } 44400a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44410a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44420a7c3937SMiklos Szeredi error = -ENOTDIR; 4443f5beed75SAl Viro if (old_last.name[old_last.len]) 44440a7c3937SMiklos Szeredi goto exit5; 4445f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44460a7c3937SMiklos Szeredi goto exit5; 44470a7c3937SMiklos Szeredi } 44480a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44490a7c3937SMiklos Szeredi error = -EINVAL; 44500a7c3937SMiklos Szeredi if (old_dentry == trap) 44510a7c3937SMiklos Szeredi goto exit5; 44521da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4453da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44541da177e4SLinus Torvalds error = -ENOTEMPTY; 44551da177e4SLinus Torvalds if (new_dentry == trap) 44561da177e4SLinus Torvalds goto exit5; 44571da177e4SLinus Torvalds 4458f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4459f5beed75SAl Viro &new_path, new_dentry, flags); 4460be6d3e56SKentaro Takeda if (error) 4461c30dabfeSJan Kara goto exit5; 4462f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4463f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4464520c8b16SMiklos Szeredi &delegated_inode, flags); 44651da177e4SLinus Torvalds exit5: 44661da177e4SLinus Torvalds dput(new_dentry); 44671da177e4SLinus Torvalds exit4: 44681da177e4SLinus Torvalds dput(old_dentry); 44691da177e4SLinus Torvalds exit3: 4470f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44718e6d782cSJ. Bruce Fields if (delegated_inode) { 44728e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44738e6d782cSJ. Bruce Fields if (!error) 44748e6d782cSJ. Bruce Fields goto retry_deleg; 44758e6d782cSJ. Bruce Fields } 4476f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44771da177e4SLinus Torvalds exit2: 4478c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4479c6a94284SJeff Layton should_retry = true; 4480f5beed75SAl Viro path_put(&new_path); 44812ad94ae6SAl Viro putname(to); 44821da177e4SLinus Torvalds exit1: 4483f5beed75SAl Viro path_put(&old_path); 44841da177e4SLinus Torvalds putname(from); 4485c6a94284SJeff Layton if (should_retry) { 4486c6a94284SJeff Layton should_retry = false; 4487c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4488c6a94284SJeff Layton goto retry; 4489c6a94284SJeff Layton } 44902ad94ae6SAl Viro exit: 44911da177e4SLinus Torvalds return error; 44921da177e4SLinus Torvalds } 44931da177e4SLinus Torvalds 4494ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4495ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4496ee81feb6SDominik Brodowski { 4497ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4498ee81feb6SDominik Brodowski } 4499ee81feb6SDominik Brodowski 4500520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4501520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4502520c8b16SMiklos Szeredi { 4503ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4504520c8b16SMiklos Szeredi } 4505520c8b16SMiklos Szeredi 4506a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45075590ff0dSUlrich Drepper { 4508ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45095590ff0dSUlrich Drepper } 45105590ff0dSUlrich Drepper 4511787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4512787fb6bcSMiklos Szeredi { 4513787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4514787fb6bcSMiklos Szeredi if (error) 4515787fb6bcSMiklos Szeredi return error; 4516787fb6bcSMiklos Szeredi 4517787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4518787fb6bcSMiklos Szeredi return -EPERM; 4519787fb6bcSMiklos Szeredi 4520787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4521787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4522787fb6bcSMiklos Szeredi } 4523787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4524787fb6bcSMiklos Szeredi 45255d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45261da177e4SLinus Torvalds { 45275d826c84SAl Viro int len = PTR_ERR(link); 45281da177e4SLinus Torvalds if (IS_ERR(link)) 45291da177e4SLinus Torvalds goto out; 45301da177e4SLinus Torvalds 45311da177e4SLinus Torvalds len = strlen(link); 45321da177e4SLinus Torvalds if (len > (unsigned) buflen) 45331da177e4SLinus Torvalds len = buflen; 45341da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45351da177e4SLinus Torvalds len = -EFAULT; 45361da177e4SLinus Torvalds out: 45371da177e4SLinus Torvalds return len; 45381da177e4SLinus Torvalds } 45391da177e4SLinus Torvalds 4540d60874cdSMiklos Szeredi /** 4541fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4542fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4543fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4544fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4545fd4a0edfSMiklos Szeredi * 4546fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4547fd4a0edfSMiklos Szeredi * 4548fd4a0edfSMiklos Szeredi * Does not call security hook. 4549fd4a0edfSMiklos Szeredi */ 4550fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4551fd4a0edfSMiklos Szeredi { 4552fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4553f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4554f2df5da6SAl Viro const char *link; 4555f2df5da6SAl Viro int res; 4556fd4a0edfSMiklos Szeredi 455776fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 455876fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 455976fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 456076fca90eSMiklos Szeredi 456176fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4562fd4a0edfSMiklos Szeredi return -EINVAL; 4563fd4a0edfSMiklos Szeredi 456476fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 456576fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 456676fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 456776fca90eSMiklos Szeredi } 456876fca90eSMiklos Szeredi 45694c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4570f2df5da6SAl Viro if (!link) { 4571f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4572f2df5da6SAl Viro if (IS_ERR(link)) 4573f2df5da6SAl Viro return PTR_ERR(link); 4574f2df5da6SAl Viro } 4575f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4576f2df5da6SAl Viro do_delayed_call(&done); 4577f2df5da6SAl Viro return res; 4578fd4a0edfSMiklos Szeredi } 4579fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 45801da177e4SLinus Torvalds 4581d60874cdSMiklos Szeredi /** 4582d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4583d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4584d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4585d60874cdSMiklos Szeredi * 4586d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4587d60874cdSMiklos Szeredi * 4588d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4589d60874cdSMiklos Szeredi * 4590d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4591d60874cdSMiklos Szeredi */ 4592d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4593d60874cdSMiklos Szeredi { 4594d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4595d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4596d60874cdSMiklos Szeredi 4597d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4598d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4599d60874cdSMiklos Szeredi if (!res) 4600d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4601d60874cdSMiklos Szeredi } 4602d60874cdSMiklos Szeredi return res; 4603d60874cdSMiklos Szeredi } 4604d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4605d60874cdSMiklos Szeredi 46061da177e4SLinus Torvalds /* get the link contents into pagecache */ 46076b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4608fceef393SAl Viro struct delayed_call *callback) 46091da177e4SLinus Torvalds { 4610ebd09abbSDuane Griffin char *kaddr; 46111da177e4SLinus Torvalds struct page *page; 46126b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46136b255391SAl Viro 4614d3883d4fSAl Viro if (!dentry) { 4615d3883d4fSAl Viro page = find_get_page(mapping, 0); 4616d3883d4fSAl Viro if (!page) 46176b255391SAl Viro return ERR_PTR(-ECHILD); 4618d3883d4fSAl Viro if (!PageUptodate(page)) { 4619d3883d4fSAl Viro put_page(page); 4620d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4621d3883d4fSAl Viro } 4622d3883d4fSAl Viro } else { 4623090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46241da177e4SLinus Torvalds if (IS_ERR(page)) 46256fe6900eSNick Piggin return (char*)page; 4626d3883d4fSAl Viro } 4627fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 462821fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 462921fc61c7SAl Viro kaddr = page_address(page); 46306b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4631ebd09abbSDuane Griffin return kaddr; 46321da177e4SLinus Torvalds } 46331da177e4SLinus Torvalds 46346b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46351da177e4SLinus Torvalds 4636fceef393SAl Viro void page_put_link(void *arg) 46371da177e4SLinus Torvalds { 4638fceef393SAl Viro put_page(arg); 46391da177e4SLinus Torvalds } 46404d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46411da177e4SLinus Torvalds 4642aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4643aa80deabSAl Viro { 4644fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46456b255391SAl Viro int res = readlink_copy(buffer, buflen, 46466b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4647fceef393SAl Viro &done)); 4648fceef393SAl Viro do_delayed_call(&done); 4649aa80deabSAl Viro return res; 4650aa80deabSAl Viro } 4651aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4652aa80deabSAl Viro 465354566b2cSNick Piggin /* 465454566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 465554566b2cSNick Piggin */ 465654566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46571da177e4SLinus Torvalds { 46581da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46590adb25d2SKirill Korotaev struct page *page; 4660afddba49SNick Piggin void *fsdata; 4661beb497abSDmitriy Monakhov int err; 4662c718a975STetsuo Handa unsigned int flags = 0; 466354566b2cSNick Piggin if (nofs) 466454566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46651da177e4SLinus Torvalds 46667e53cac4SNeilBrown retry: 4667afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 466854566b2cSNick Piggin flags, &page, &fsdata); 46691da177e4SLinus Torvalds if (err) 4670afddba49SNick Piggin goto fail; 4671afddba49SNick Piggin 467221fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4673afddba49SNick Piggin 4674afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4675afddba49SNick Piggin page, fsdata); 46761da177e4SLinus Torvalds if (err < 0) 46771da177e4SLinus Torvalds goto fail; 4678afddba49SNick Piggin if (err < len-1) 4679afddba49SNick Piggin goto retry; 4680afddba49SNick Piggin 46811da177e4SLinus Torvalds mark_inode_dirty(inode); 46821da177e4SLinus Torvalds return 0; 46831da177e4SLinus Torvalds fail: 46841da177e4SLinus Torvalds return err; 46851da177e4SLinus Torvalds } 46864d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 46871da177e4SLinus Torvalds 46880adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 46890adb25d2SKirill Korotaev { 46900adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4691c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 46920adb25d2SKirill Korotaev } 46934d359507SAl Viro EXPORT_SYMBOL(page_symlink); 46940adb25d2SKirill Korotaev 469592e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 46966b255391SAl Viro .get_link = page_get_link, 46971da177e4SLinus Torvalds }; 46981da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4699