1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * linux/fs/namei.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds 81da177e4SLinus Torvalds /* 91da177e4SLinus Torvalds * Some corrections by tytso. 101da177e4SLinus Torvalds */ 111da177e4SLinus Torvalds 121da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 131da177e4SLinus Torvalds * lookup logic. 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 161da177e4SLinus Torvalds */ 171da177e4SLinus Torvalds 181da177e4SLinus Torvalds #include <linux/init.h> 19630d9c47SPaul Gortmaker #include <linux/export.h> 2044696908SDavid S. Miller #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/slab.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/namei.h> 241da177e4SLinus Torvalds #include <linux/pagemap.h> 250eeca283SRobert Love #include <linux/fsnotify.h> 261da177e4SLinus Torvalds #include <linux/personality.h> 271da177e4SLinus Torvalds #include <linux/security.h> 286146f0d5SMimi Zohar #include <linux/ima.h> 291da177e4SLinus Torvalds #include <linux/syscalls.h> 301da177e4SLinus Torvalds #include <linux/mount.h> 311da177e4SLinus Torvalds #include <linux/audit.h> 3216f7e0feSRandy Dunlap #include <linux/capability.h> 33834f2a4aSTrond Myklebust #include <linux/file.h> 345590ff0dSUlrich Drepper #include <linux/fcntl.h> 3508ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 365ad4e53bSAl Viro #include <linux/fs_struct.h> 37e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3899d263d4SLinus Torvalds #include <linux/hash.h> 392a18da7aSGeorge Spelvin #include <linux/bitops.h> 40aeaa4a79SEric W. Biederman #include <linux/init_task.h> 417c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 421da177e4SLinus Torvalds 43e81e3f4dSEric Paris #include "internal.h" 44c7105365SAl Viro #include "mount.h" 45e81e3f4dSEric Paris 461da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 471da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 481da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 491da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 501da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 511da177e4SLinus Torvalds * 521da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 531da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 541da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 551da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 561da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 571da177e4SLinus Torvalds * the special cases of the former code. 581da177e4SLinus Torvalds * 591da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 601da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 611da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 641da177e4SLinus Torvalds * resolution to correspond with current state of the code. 651da177e4SLinus Torvalds * 661da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 671da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 681da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 691da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 701da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 711da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 721da177e4SLinus Torvalds */ 731da177e4SLinus Torvalds 741da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 751da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 761da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 771da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 781da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 791da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 8025985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 811da177e4SLinus Torvalds * 821da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 831da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 841da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 851da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 861da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 871da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 881da177e4SLinus Torvalds * and in the old Linux semantics. 891da177e4SLinus Torvalds */ 901da177e4SLinus Torvalds 911da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 921da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 931da177e4SLinus Torvalds * 941da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 951da177e4SLinus Torvalds */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 981da177e4SLinus Torvalds * inside the path - always follow. 991da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 1001da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 1011da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 1021da177e4SLinus Torvalds * otherwise - don't follow. 1031da177e4SLinus Torvalds * (applied in that order). 1041da177e4SLinus Torvalds * 1051da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1061da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1071da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1081da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1091da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1101da177e4SLinus Torvalds */ 1111da177e4SLinus Torvalds /* 1121da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 113a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1141da177e4SLinus Torvalds * any extra contention... 1151da177e4SLinus Torvalds */ 1161da177e4SLinus Torvalds 1171da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1181da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1191da177e4SLinus Torvalds * kernel data space before using them.. 1201da177e4SLinus Torvalds * 1211da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1221da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1231da177e4SLinus Torvalds */ 1247950e385SJeff Layton 125fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12691a27b2aSJeff Layton 12751f39a1fSDavid Drysdale struct filename * 12891a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12991a27b2aSJeff Layton { 13094b5d262SAl Viro struct filename *result; 1317950e385SJeff Layton char *kname; 13294b5d262SAl Viro int len; 1331da177e4SLinus Torvalds 1347ac86265SJeff Layton result = audit_reusename(filename); 1357ac86265SJeff Layton if (result) 1367ac86265SJeff Layton return result; 1377ac86265SJeff Layton 1387950e385SJeff Layton result = __getname(); 1393f9f0aa6SLinus Torvalds if (unlikely(!result)) 1404043cde8SEric Paris return ERR_PTR(-ENOMEM); 1411da177e4SLinus Torvalds 1427950e385SJeff Layton /* 1437950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1447950e385SJeff Layton * allocation 1457950e385SJeff Layton */ 146fd2f7cb5SAl Viro kname = (char *)result->iname; 14791a27b2aSJeff Layton result->name = kname; 1487950e385SJeff Layton 14994b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 15091a27b2aSJeff Layton if (unlikely(len < 0)) { 15194b5d262SAl Viro __putname(result); 15294b5d262SAl Viro return ERR_PTR(len); 15391a27b2aSJeff Layton } 1543f9f0aa6SLinus Torvalds 1557950e385SJeff Layton /* 1567950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1577950e385SJeff Layton * separate struct filename so we can dedicate the entire 1587950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1597950e385SJeff Layton * userland. 1607950e385SJeff Layton */ 16194b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 162fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1637950e385SJeff Layton kname = (char *)result; 1647950e385SJeff Layton 165fd2f7cb5SAl Viro /* 166fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 167fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 168fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 169fd2f7cb5SAl Viro */ 170fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 17194b5d262SAl Viro if (unlikely(!result)) { 17294b5d262SAl Viro __putname(kname); 17394b5d262SAl Viro return ERR_PTR(-ENOMEM); 1747950e385SJeff Layton } 1757950e385SJeff Layton result->name = kname; 17694b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17794b5d262SAl Viro if (unlikely(len < 0)) { 17894b5d262SAl Viro __putname(kname); 17994b5d262SAl Viro kfree(result); 18094b5d262SAl Viro return ERR_PTR(len); 18194b5d262SAl Viro } 18294b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18394b5d262SAl Viro __putname(kname); 18494b5d262SAl Viro kfree(result); 18594b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18694b5d262SAl Viro } 1877950e385SJeff Layton } 1887950e385SJeff Layton 18994b5d262SAl Viro result->refcnt = 1; 1903f9f0aa6SLinus Torvalds /* The empty path is special. */ 1913f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1923f9f0aa6SLinus Torvalds if (empty) 1931fa1e7f6SAndy Whitcroft *empty = 1; 19494b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19594b5d262SAl Viro putname(result); 19694b5d262SAl Viro return ERR_PTR(-ENOENT); 1971da177e4SLinus Torvalds } 19894b5d262SAl Viro } 1997950e385SJeff Layton 2007950e385SJeff Layton result->uptr = filename; 201c4ad8f98SLinus Torvalds result->aname = NULL; 2021da177e4SLinus Torvalds audit_getname(result); 2031da177e4SLinus Torvalds return result; 2043f9f0aa6SLinus Torvalds } 2053f9f0aa6SLinus Torvalds 20691a27b2aSJeff Layton struct filename * 20791a27b2aSJeff Layton getname(const char __user * filename) 208f52e0c11SAl Viro { 209f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 210f52e0c11SAl Viro } 211f52e0c11SAl Viro 212c4ad8f98SLinus Torvalds struct filename * 213c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 214c4ad8f98SLinus Torvalds { 215c4ad8f98SLinus Torvalds struct filename *result; 21608518549SPaul Moore int len = strlen(filename) + 1; 217c4ad8f98SLinus Torvalds 218c4ad8f98SLinus Torvalds result = __getname(); 219c4ad8f98SLinus Torvalds if (unlikely(!result)) 220c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 221c4ad8f98SLinus Torvalds 22208518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 223fd2f7cb5SAl Viro result->name = (char *)result->iname; 22408518549SPaul Moore } else if (len <= PATH_MAX) { 22530ce4d19SAl Viro const size_t size = offsetof(struct filename, iname[1]); 22608518549SPaul Moore struct filename *tmp; 22708518549SPaul Moore 22830ce4d19SAl Viro tmp = kmalloc(size, GFP_KERNEL); 22908518549SPaul Moore if (unlikely(!tmp)) { 23008518549SPaul Moore __putname(result); 23108518549SPaul Moore return ERR_PTR(-ENOMEM); 23208518549SPaul Moore } 23308518549SPaul Moore tmp->name = (char *)result; 23408518549SPaul Moore result = tmp; 23508518549SPaul Moore } else { 23608518549SPaul Moore __putname(result); 23708518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23808518549SPaul Moore } 23908518549SPaul Moore memcpy((char *)result->name, filename, len); 240c4ad8f98SLinus Torvalds result->uptr = NULL; 241c4ad8f98SLinus Torvalds result->aname = NULL; 24255422d0bSPaul Moore result->refcnt = 1; 243fd3522fdSPaul Moore audit_getname(result); 244c4ad8f98SLinus Torvalds 245c4ad8f98SLinus Torvalds return result; 246c4ad8f98SLinus Torvalds } 247c4ad8f98SLinus Torvalds 24891a27b2aSJeff Layton void putname(struct filename *name) 2491da177e4SLinus Torvalds { 25055422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 25155422d0bSPaul Moore 25255422d0bSPaul Moore if (--name->refcnt > 0) 25355422d0bSPaul Moore return; 25455422d0bSPaul Moore 255fd2f7cb5SAl Viro if (name->name != name->iname) { 25655422d0bSPaul Moore __putname(name->name); 25755422d0bSPaul Moore kfree(name); 25855422d0bSPaul Moore } else 25955422d0bSPaul Moore __putname(name); 2601da177e4SLinus Torvalds } 2611da177e4SLinus Torvalds 262e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 263e77819e5SLinus Torvalds { 26484635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 265e77819e5SLinus Torvalds struct posix_acl *acl; 266e77819e5SLinus Torvalds 267e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2683567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2693567866bSAl Viro if (!acl) 270e77819e5SLinus Torvalds return -EAGAIN; 2713567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 272b8a7a3a6SAndreas Gruenbacher if (is_uncached_acl(acl)) 273e77819e5SLinus Torvalds return -ECHILD; 274206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 275e77819e5SLinus Torvalds } 276e77819e5SLinus Torvalds 2772982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2784e34e719SChristoph Hellwig if (IS_ERR(acl)) 2794e34e719SChristoph Hellwig return PTR_ERR(acl); 280e77819e5SLinus Torvalds if (acl) { 281e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 282e77819e5SLinus Torvalds posix_acl_release(acl); 283e77819e5SLinus Torvalds return error; 284e77819e5SLinus Torvalds } 28584635d68SLinus Torvalds #endif 286e77819e5SLinus Torvalds 287e77819e5SLinus Torvalds return -EAGAIN; 288e77819e5SLinus Torvalds } 289e77819e5SLinus Torvalds 2905909ccaaSLinus Torvalds /* 291948409c7SAndreas Gruenbacher * This does the basic permission checking 2925909ccaaSLinus Torvalds */ 2937e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2945909ccaaSLinus Torvalds { 29526cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2965909ccaaSLinus Torvalds 2978e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2985909ccaaSLinus Torvalds mode >>= 6; 2995909ccaaSLinus Torvalds else { 300e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 3017e40145eSAl Viro int error = check_acl(inode, mask); 3025909ccaaSLinus Torvalds if (error != -EAGAIN) 3035909ccaaSLinus Torvalds return error; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3075909ccaaSLinus Torvalds mode >>= 3; 3085909ccaaSLinus Torvalds } 3095909ccaaSLinus Torvalds 3105909ccaaSLinus Torvalds /* 3115909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3125909ccaaSLinus Torvalds */ 3139c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3145909ccaaSLinus Torvalds return 0; 3155909ccaaSLinus Torvalds return -EACCES; 3165909ccaaSLinus Torvalds } 3171da177e4SLinus Torvalds 3181da177e4SLinus Torvalds /** 3191da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3201da177e4SLinus Torvalds * @inode: inode to check access rights for 3218fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3221da177e4SLinus Torvalds * 3231da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3241da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3251da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 326b74c79e9SNick Piggin * are used for other things. 327b74c79e9SNick Piggin * 328b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 329b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 330b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3311da177e4SLinus Torvalds */ 3322830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3331da177e4SLinus Torvalds { 3345909ccaaSLinus Torvalds int ret; 3351da177e4SLinus Torvalds 3361da177e4SLinus Torvalds /* 337948409c7SAndreas Gruenbacher * Do the basic permission checks. 3381da177e4SLinus Torvalds */ 3397e40145eSAl Viro ret = acl_permission_check(inode, mask); 3405909ccaaSLinus Torvalds if (ret != -EACCES) 3415909ccaaSLinus Torvalds return ret; 3421da177e4SLinus Torvalds 343d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 344d594e7ecSAl Viro /* DACs are overridable for directories */ 345d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34623adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34723adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 348d594e7ecSAl Viro return 0; 34923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3501da177e4SLinus Torvalds return 0; 3512a4c2242SStephen Smalley return -EACCES; 3522a4c2242SStephen Smalley } 3531da177e4SLinus Torvalds 3541da177e4SLinus Torvalds /* 3551da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3561da177e4SLinus Torvalds */ 3577ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 358d594e7ecSAl Viro if (mask == MAY_READ) 35923adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3601da177e4SLinus Torvalds return 0; 3612a4c2242SStephen Smalley /* 3622a4c2242SStephen Smalley * Read/write DACs are always overridable. 3632a4c2242SStephen Smalley * Executable DACs are overridable when there is 3642a4c2242SStephen Smalley * at least one exec bit set. 3652a4c2242SStephen Smalley */ 3662a4c2242SStephen Smalley if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 3672a4c2242SStephen Smalley if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3682a4c2242SStephen Smalley return 0; 3691da177e4SLinus Torvalds 3701da177e4SLinus Torvalds return -EACCES; 3711da177e4SLinus Torvalds } 3724d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3731da177e4SLinus Torvalds 3743ddcd056SLinus Torvalds /* 3753ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3763ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3773ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3783ddcd056SLinus Torvalds * permission function, use the fast case". 3793ddcd056SLinus Torvalds */ 3803ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3813ddcd056SLinus Torvalds { 3823ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3833ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3843ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3853ddcd056SLinus Torvalds 3863ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3873ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3883ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3893ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3903ddcd056SLinus Torvalds } 3913ddcd056SLinus Torvalds return generic_permission(inode, mask); 3923ddcd056SLinus Torvalds } 3933ddcd056SLinus Torvalds 394cb23beb5SChristoph Hellwig /** 3950bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 3960bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 39755852635SRandy Dunlap * @inode: Inode to check permission on 3980bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 3990bdaea90SDavid Howells * 4000bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4010bdaea90SDavid Howells */ 4020bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4030bdaea90SDavid Howells { 4040bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4050bdaea90SDavid Howells umode_t mode = inode->i_mode; 4060bdaea90SDavid Howells 4070bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 408bc98a42cSDavid Howells if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4090bdaea90SDavid Howells return -EROFS; 4100bdaea90SDavid Howells } 4110bdaea90SDavid Howells return 0; 4120bdaea90SDavid Howells } 4130bdaea90SDavid Howells 4140bdaea90SDavid Howells /** 4150bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4160bdaea90SDavid Howells * @inode: Inode to check permission on 4170bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4180bdaea90SDavid Howells * 4190bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4200bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4210bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4220bdaea90SDavid Howells * 4230bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4240bdaea90SDavid Howells */ 4250bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4260bdaea90SDavid Howells { 4270bdaea90SDavid Howells int retval; 4280bdaea90SDavid Howells 4290bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4300bdaea90SDavid Howells if (retval) 4310bdaea90SDavid Howells return retval; 4324bfd054aSEric Biggers 4334bfd054aSEric Biggers if (unlikely(mask & MAY_WRITE)) { 4344bfd054aSEric Biggers /* 4354bfd054aSEric Biggers * Nobody gets write access to an immutable file. 4364bfd054aSEric Biggers */ 4374bfd054aSEric Biggers if (IS_IMMUTABLE(inode)) 4384bfd054aSEric Biggers return -EPERM; 4394bfd054aSEric Biggers 4404bfd054aSEric Biggers /* 4414bfd054aSEric Biggers * Updating mtime will likely cause i_uid and i_gid to be 4424bfd054aSEric Biggers * written back improperly if their true value is unknown 4434bfd054aSEric Biggers * to the vfs. 4444bfd054aSEric Biggers */ 4454bfd054aSEric Biggers if (HAS_UNMAPPED_ID(inode)) 4464bfd054aSEric Biggers return -EACCES; 4474bfd054aSEric Biggers } 4484bfd054aSEric Biggers 4494bfd054aSEric Biggers retval = do_inode_permission(inode, mask); 4504bfd054aSEric Biggers if (retval) 4514bfd054aSEric Biggers return retval; 4524bfd054aSEric Biggers 4534bfd054aSEric Biggers retval = devcgroup_inode_permission(inode, mask); 4544bfd054aSEric Biggers if (retval) 4554bfd054aSEric Biggers return retval; 4564bfd054aSEric Biggers 4574bfd054aSEric Biggers return security_inode_permission(inode, mask); 4580bdaea90SDavid Howells } 4594d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4600bdaea90SDavid Howells 4610bdaea90SDavid Howells /** 4625dd784d0SJan Blunck * path_get - get a reference to a path 4635dd784d0SJan Blunck * @path: path to get the reference to 4645dd784d0SJan Blunck * 4655dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4665dd784d0SJan Blunck */ 467dcf787f3SAl Viro void path_get(const struct path *path) 4685dd784d0SJan Blunck { 4695dd784d0SJan Blunck mntget(path->mnt); 4705dd784d0SJan Blunck dget(path->dentry); 4715dd784d0SJan Blunck } 4725dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4735dd784d0SJan Blunck 4745dd784d0SJan Blunck /** 4751d957f9bSJan Blunck * path_put - put a reference to a path 4761d957f9bSJan Blunck * @path: path to put the reference to 4771d957f9bSJan Blunck * 4781d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4791d957f9bSJan Blunck */ 480dcf787f3SAl Viro void path_put(const struct path *path) 4811da177e4SLinus Torvalds { 4821d957f9bSJan Blunck dput(path->dentry); 4831d957f9bSJan Blunck mntput(path->mnt); 4841da177e4SLinus Torvalds } 4851d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4861da177e4SLinus Torvalds 487894bc8c4SAl Viro #define EMBEDDED_LEVELS 2 4881f55a6ecSAl Viro struct nameidata { 4891f55a6ecSAl Viro struct path path; 4901f55a6ecSAl Viro struct qstr last; 4911f55a6ecSAl Viro struct path root; 4921f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 4931f55a6ecSAl Viro unsigned int flags; 494ab87f9a5SAleksa Sarai unsigned seq, m_seq, r_seq; 4951f55a6ecSAl Viro int last_type; 4961f55a6ecSAl Viro unsigned depth; 497756daf26SNeilBrown int total_link_count; 498697fc6caSAl Viro struct saved { 499697fc6caSAl Viro struct path link; 500fceef393SAl Viro struct delayed_call done; 501697fc6caSAl Viro const char *name; 5020450b2d1SAl Viro unsigned seq; 503894bc8c4SAl Viro } *stack, internal[EMBEDDED_LEVELS]; 5049883d185SAl Viro struct filename *name; 5059883d185SAl Viro struct nameidata *saved; 5069883d185SAl Viro unsigned root_seq; 5079883d185SAl Viro int dfd; 5083859a271SKees Cook } __randomize_layout; 5091f55a6ecSAl Viro 5109883d185SAl Viro static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) 511894bc8c4SAl Viro { 512756daf26SNeilBrown struct nameidata *old = current->nameidata; 513756daf26SNeilBrown p->stack = p->internal; 514c8a53ee5SAl Viro p->dfd = dfd; 515c8a53ee5SAl Viro p->name = name; 516756daf26SNeilBrown p->total_link_count = old ? old->total_link_count : 0; 5179883d185SAl Viro p->saved = old; 518756daf26SNeilBrown current->nameidata = p; 519894bc8c4SAl Viro } 520894bc8c4SAl Viro 5219883d185SAl Viro static void restore_nameidata(void) 522894bc8c4SAl Viro { 5239883d185SAl Viro struct nameidata *now = current->nameidata, *old = now->saved; 524756daf26SNeilBrown 525756daf26SNeilBrown current->nameidata = old; 526756daf26SNeilBrown if (old) 527756daf26SNeilBrown old->total_link_count = now->total_link_count; 528e1a63bbcSAl Viro if (now->stack != now->internal) 529756daf26SNeilBrown kfree(now->stack); 530894bc8c4SAl Viro } 531894bc8c4SAl Viro 532894bc8c4SAl Viro static int __nd_alloc_stack(struct nameidata *nd) 533894bc8c4SAl Viro { 534bc40aee0SAl Viro struct saved *p; 535bc40aee0SAl Viro 536bc40aee0SAl Viro if (nd->flags & LOOKUP_RCU) { 5376da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 538bc40aee0SAl Viro GFP_ATOMIC); 539bc40aee0SAl Viro if (unlikely(!p)) 540bc40aee0SAl Viro return -ECHILD; 541bc40aee0SAl Viro } else { 5426da2ec56SKees Cook p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), 543894bc8c4SAl Viro GFP_KERNEL); 544894bc8c4SAl Viro if (unlikely(!p)) 545894bc8c4SAl Viro return -ENOMEM; 546bc40aee0SAl Viro } 547894bc8c4SAl Viro memcpy(p, nd->internal, sizeof(nd->internal)); 548894bc8c4SAl Viro nd->stack = p; 549894bc8c4SAl Viro return 0; 550894bc8c4SAl Viro } 551894bc8c4SAl Viro 552397d425dSEric W. Biederman /** 5536b03f7edSAl Viro * path_connected - Verify that a dentry is below mnt.mnt_root 554397d425dSEric W. Biederman * 555397d425dSEric W. Biederman * Rename can sometimes move a file or directory outside of a bind 556397d425dSEric W. Biederman * mount, path_connected allows those cases to be detected. 557397d425dSEric W. Biederman */ 5586b03f7edSAl Viro static bool path_connected(struct vfsmount *mnt, struct dentry *dentry) 559397d425dSEric W. Biederman { 56095dd7758SEric W. Biederman struct super_block *sb = mnt->mnt_sb; 561397d425dSEric W. Biederman 56295dd7758SEric W. Biederman /* Bind mounts and multi-root filesystems can have disconnected paths */ 56395dd7758SEric W. Biederman if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) 564397d425dSEric W. Biederman return true; 565397d425dSEric W. Biederman 5666b03f7edSAl Viro return is_subdir(dentry, mnt->mnt_root); 567397d425dSEric W. Biederman } 568397d425dSEric W. Biederman 569894bc8c4SAl Viro static inline int nd_alloc_stack(struct nameidata *nd) 570894bc8c4SAl Viro { 571da4e0be0SAl Viro if (likely(nd->depth != EMBEDDED_LEVELS)) 572894bc8c4SAl Viro return 0; 573894bc8c4SAl Viro if (likely(nd->stack != nd->internal)) 574894bc8c4SAl Viro return 0; 575894bc8c4SAl Viro return __nd_alloc_stack(nd); 576894bc8c4SAl Viro } 577894bc8c4SAl Viro 5787973387aSAl Viro static void drop_links(struct nameidata *nd) 5797973387aSAl Viro { 5807973387aSAl Viro int i = nd->depth; 5817973387aSAl Viro while (i--) { 5827973387aSAl Viro struct saved *last = nd->stack + i; 583fceef393SAl Viro do_delayed_call(&last->done); 584fceef393SAl Viro clear_delayed_call(&last->done); 5857973387aSAl Viro } 5867973387aSAl Viro } 5877973387aSAl Viro 5887973387aSAl Viro static void terminate_walk(struct nameidata *nd) 5897973387aSAl Viro { 5907973387aSAl Viro drop_links(nd); 5917973387aSAl Viro if (!(nd->flags & LOOKUP_RCU)) { 5927973387aSAl Viro int i; 5937973387aSAl Viro path_put(&nd->path); 5947973387aSAl Viro for (i = 0; i < nd->depth; i++) 5957973387aSAl Viro path_put(&nd->stack[i].link); 59684a2bd39SAl Viro if (nd->flags & LOOKUP_ROOT_GRABBED) { 597102b8af2SAl Viro path_put(&nd->root); 59884a2bd39SAl Viro nd->flags &= ~LOOKUP_ROOT_GRABBED; 599102b8af2SAl Viro } 6007973387aSAl Viro } else { 6017973387aSAl Viro nd->flags &= ~LOOKUP_RCU; 6027973387aSAl Viro rcu_read_unlock(); 6037973387aSAl Viro } 6047973387aSAl Viro nd->depth = 0; 6057973387aSAl Viro } 6067973387aSAl Viro 6077973387aSAl Viro /* path_put is needed afterwards regardless of success or failure */ 6082aa38470SAl Viro static bool __legitimize_path(struct path *path, unsigned seq, unsigned mseq) 6097973387aSAl Viro { 6102aa38470SAl Viro int res = __legitimize_mnt(path->mnt, mseq); 6117973387aSAl Viro if (unlikely(res)) { 6127973387aSAl Viro if (res > 0) 6137973387aSAl Viro path->mnt = NULL; 6147973387aSAl Viro path->dentry = NULL; 6157973387aSAl Viro return false; 6167973387aSAl Viro } 6177973387aSAl Viro if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { 6187973387aSAl Viro path->dentry = NULL; 6197973387aSAl Viro return false; 6207973387aSAl Viro } 6217973387aSAl Viro return !read_seqcount_retry(&path->dentry->d_seq, seq); 6227973387aSAl Viro } 6237973387aSAl Viro 6242aa38470SAl Viro static inline bool legitimize_path(struct nameidata *nd, 6252aa38470SAl Viro struct path *path, unsigned seq) 6262aa38470SAl Viro { 6272aa38470SAl Viro return __legitimize_path(path, nd->m_seq, seq); 6282aa38470SAl Viro } 6292aa38470SAl Viro 6307973387aSAl Viro static bool legitimize_links(struct nameidata *nd) 6317973387aSAl Viro { 6327973387aSAl Viro int i; 6337973387aSAl Viro for (i = 0; i < nd->depth; i++) { 6347973387aSAl Viro struct saved *last = nd->stack + i; 6357973387aSAl Viro if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { 6367973387aSAl Viro drop_links(nd); 6377973387aSAl Viro nd->depth = i + 1; 6387973387aSAl Viro return false; 6397973387aSAl Viro } 6407973387aSAl Viro } 6417973387aSAl Viro return true; 6427973387aSAl Viro } 6437973387aSAl Viro 644ee594bffSAl Viro static bool legitimize_root(struct nameidata *nd) 645ee594bffSAl Viro { 646adb21d2bSAleksa Sarai /* 647adb21d2bSAleksa Sarai * For scoped-lookups (where nd->root has been zeroed), we need to 648adb21d2bSAleksa Sarai * restart the whole lookup from scratch -- because set_root() is wrong 649adb21d2bSAleksa Sarai * for these lookups (nd->dfd is the root, not the filesystem root). 650adb21d2bSAleksa Sarai */ 651adb21d2bSAleksa Sarai if (!nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)) 652adb21d2bSAleksa Sarai return false; 653adb21d2bSAleksa Sarai /* Nothing to do if nd->root is zero or is managed by the VFS user. */ 654ee594bffSAl Viro if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) 655ee594bffSAl Viro return true; 65684a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 657ee594bffSAl Viro return legitimize_path(nd, &nd->root, nd->root_seq); 658ee594bffSAl Viro } 659ee594bffSAl Viro 66019660af7SAl Viro /* 66131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 66219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 66319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 66457e3715cSMike Marshall * normal reference counts on dentries and vfsmounts to transition to ref-walk 66519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 66619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 66719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 66819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 66931e6b01fSNick Piggin */ 67031e6b01fSNick Piggin 67131e6b01fSNick Piggin /** 67219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 67319660af7SAl Viro * @nd: nameidata pathwalk data 67439191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 67531e6b01fSNick Piggin * 6764675ac39SAl Viro * unlazy_walk attempts to legitimize the current nd->path and nd->root 6774675ac39SAl Viro * for ref-walk mode. 6784675ac39SAl Viro * Must be called from rcu-walk context. 6797973387aSAl Viro * Nothing should touch nameidata between unlazy_walk() failure and 6807973387aSAl Viro * terminate_walk(). 68131e6b01fSNick Piggin */ 6824675ac39SAl Viro static int unlazy_walk(struct nameidata *nd) 68331e6b01fSNick Piggin { 68431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 68531e6b01fSNick Piggin 68631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 687e5c832d5SLinus Torvalds 688e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 6897973387aSAl Viro if (unlikely(!legitimize_links(nd))) 6904675ac39SAl Viro goto out1; 69184a2bd39SAl Viro if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) 69284a2bd39SAl Viro goto out; 693ee594bffSAl Viro if (unlikely(!legitimize_root(nd))) 6944675ac39SAl Viro goto out; 6954675ac39SAl Viro rcu_read_unlock(); 6964675ac39SAl Viro BUG_ON(nd->inode != parent->d_inode); 6974675ac39SAl Viro return 0; 6984675ac39SAl Viro 69984a2bd39SAl Viro out1: 7004675ac39SAl Viro nd->path.mnt = NULL; 7014675ac39SAl Viro nd->path.dentry = NULL; 7024675ac39SAl Viro out: 7034675ac39SAl Viro rcu_read_unlock(); 7044675ac39SAl Viro return -ECHILD; 7054675ac39SAl Viro } 7064675ac39SAl Viro 7074675ac39SAl Viro /** 7084675ac39SAl Viro * unlazy_child - try to switch to ref-walk mode. 7094675ac39SAl Viro * @nd: nameidata pathwalk data 7104675ac39SAl Viro * @dentry: child of nd->path.dentry 7114675ac39SAl Viro * @seq: seq number to check dentry against 7124675ac39SAl Viro * Returns: 0 on success, -ECHILD on failure 7134675ac39SAl Viro * 7144675ac39SAl Viro * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry 7154675ac39SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 7164675ac39SAl Viro * @nd. Must be called from rcu-walk context. 7174675ac39SAl Viro * Nothing should touch nameidata between unlazy_child() failure and 7184675ac39SAl Viro * terminate_walk(). 7194675ac39SAl Viro */ 7204675ac39SAl Viro static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) 7214675ac39SAl Viro { 7224675ac39SAl Viro BUG_ON(!(nd->flags & LOOKUP_RCU)); 7234675ac39SAl Viro 7244675ac39SAl Viro nd->flags &= ~LOOKUP_RCU; 7254675ac39SAl Viro if (unlikely(!legitimize_links(nd))) 7264675ac39SAl Viro goto out2; 7277973387aSAl Viro if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) 7287973387aSAl Viro goto out2; 7294675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) 7307973387aSAl Viro goto out1; 73148a066e7SAl Viro 73215570086SLinus Torvalds /* 7334675ac39SAl Viro * We need to move both the parent and the dentry from the RCU domain 7344675ac39SAl Viro * to be properly refcounted. And the sequence number in the dentry 7354675ac39SAl Viro * validates *both* dentry counters, since we checked the sequence 7364675ac39SAl Viro * number of the parent after we got the child sequence number. So we 7374675ac39SAl Viro * know the parent must still be valid if the child sequence number is 73815570086SLinus Torvalds */ 7394675ac39SAl Viro if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) 740e5c832d5SLinus Torvalds goto out; 74184a2bd39SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 74284a2bd39SAl Viro goto out_dput; 743e5c832d5SLinus Torvalds /* 744e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 745e5c832d5SLinus Torvalds * still valid and get it if required. 746e5c832d5SLinus Torvalds */ 74784a2bd39SAl Viro if (unlikely(!legitimize_root(nd))) 74884a2bd39SAl Viro goto out_dput; 7498b61e74fSAl Viro rcu_read_unlock(); 75031e6b01fSNick Piggin return 0; 75119660af7SAl Viro 7527973387aSAl Viro out2: 7537973387aSAl Viro nd->path.mnt = NULL; 7547973387aSAl Viro out1: 7557973387aSAl Viro nd->path.dentry = NULL; 756e5c832d5SLinus Torvalds out: 7578b61e74fSAl Viro rcu_read_unlock(); 75884a2bd39SAl Viro return -ECHILD; 75984a2bd39SAl Viro out_dput: 76084a2bd39SAl Viro rcu_read_unlock(); 76184a2bd39SAl Viro dput(dentry); 76231e6b01fSNick Piggin return -ECHILD; 76331e6b01fSNick Piggin } 76431e6b01fSNick Piggin 7654ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 76634286d66SNick Piggin { 767a89f8337SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) 7684ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 769a89f8337SAl Viro else 770a89f8337SAl Viro return 1; 77134286d66SNick Piggin } 77234286d66SNick Piggin 7739f1fafeeSAl Viro /** 7749f1fafeeSAl Viro * complete_walk - successful completion of path walk 7759f1fafeeSAl Viro * @nd: pointer nameidata 77639159de2SJeff Layton * 7779f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 7789f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 7799f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 7809f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 7819f1fafeeSAl Viro * need to drop nd->path. 78239159de2SJeff Layton */ 7839f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 78439159de2SJeff Layton { 78516c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 78639159de2SJeff Layton int status; 78739159de2SJeff Layton 7889f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 789adb21d2bSAleksa Sarai /* 790adb21d2bSAleksa Sarai * We don't want to zero nd->root for scoped-lookups or 791adb21d2bSAleksa Sarai * externally-managed nd->root. 792adb21d2bSAleksa Sarai */ 793adb21d2bSAleksa Sarai if (!(nd->flags & (LOOKUP_ROOT | LOOKUP_IS_SCOPED))) 7949f1fafeeSAl Viro nd->root.mnt = NULL; 7954675ac39SAl Viro if (unlikely(unlazy_walk(nd))) 79648a066e7SAl Viro return -ECHILD; 79748a066e7SAl Viro } 7989f1fafeeSAl Viro 799adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 800adb21d2bSAleksa Sarai /* 801adb21d2bSAleksa Sarai * While the guarantee of LOOKUP_IS_SCOPED is (roughly) "don't 802adb21d2bSAleksa Sarai * ever step outside the root during lookup" and should already 803adb21d2bSAleksa Sarai * be guaranteed by the rest of namei, we want to avoid a namei 804adb21d2bSAleksa Sarai * BUG resulting in userspace being given a path that was not 805adb21d2bSAleksa Sarai * scoped within the root at some point during the lookup. 806adb21d2bSAleksa Sarai * 807adb21d2bSAleksa Sarai * So, do a final sanity-check to make sure that in the 808adb21d2bSAleksa Sarai * worst-case scenario (a complete bypass of LOOKUP_IS_SCOPED) 809adb21d2bSAleksa Sarai * we won't silently return an fd completely outside of the 810adb21d2bSAleksa Sarai * requested root to userspace. 811adb21d2bSAleksa Sarai * 812adb21d2bSAleksa Sarai * Userspace could move the path outside the root after this 813adb21d2bSAleksa Sarai * check, but as discussed elsewhere this is not a concern (the 814adb21d2bSAleksa Sarai * resolved file was inside the root at some point). 815adb21d2bSAleksa Sarai */ 816adb21d2bSAleksa Sarai if (!path_is_under(&nd->path, &nd->root)) 817adb21d2bSAleksa Sarai return -EXDEV; 818adb21d2bSAleksa Sarai } 819adb21d2bSAleksa Sarai 82016c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 82139159de2SJeff Layton return 0; 82239159de2SJeff Layton 823ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 82416c2cd71SAl Viro return 0; 82516c2cd71SAl Viro 826ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 82739159de2SJeff Layton if (status > 0) 82839159de2SJeff Layton return 0; 82939159de2SJeff Layton 83016c2cd71SAl Viro if (!status) 83139159de2SJeff Layton status = -ESTALE; 83216c2cd71SAl Viro 83339159de2SJeff Layton return status; 83439159de2SJeff Layton } 83539159de2SJeff Layton 836740a1678SAleksa Sarai static int set_root(struct nameidata *nd) 8372a737871SAl Viro { 83831e6b01fSNick Piggin struct fs_struct *fs = current->fs; 8399e6697e2SAl Viro 840adb21d2bSAleksa Sarai /* 841adb21d2bSAleksa Sarai * Jumping to the real root in a scoped-lookup is a BUG in namei, but we 842adb21d2bSAleksa Sarai * still have to ensure it doesn't happen because it will cause a breakout 843adb21d2bSAleksa Sarai * from the dirfd. 844adb21d2bSAleksa Sarai */ 845adb21d2bSAleksa Sarai if (WARN_ON(nd->flags & LOOKUP_IS_SCOPED)) 846adb21d2bSAleksa Sarai return -ENOTRECOVERABLE; 847adb21d2bSAleksa Sarai 8489e6697e2SAl Viro if (nd->flags & LOOKUP_RCU) { 8498f47a016SAl Viro unsigned seq; 850c28cc364SNick Piggin 851c28cc364SNick Piggin do { 852c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 85331e6b01fSNick Piggin nd->root = fs->root; 8548f47a016SAl Viro nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); 855c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 8569e6697e2SAl Viro } else { 8579e6697e2SAl Viro get_fs_root(fs, &nd->root); 85884a2bd39SAl Viro nd->flags |= LOOKUP_ROOT_GRABBED; 8599e6697e2SAl Viro } 860740a1678SAleksa Sarai return 0; 86131e6b01fSNick Piggin } 86231e6b01fSNick Piggin 863248fb5b9SAl Viro static int nd_jump_root(struct nameidata *nd) 864248fb5b9SAl Viro { 865adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_BENEATH)) 866adb21d2bSAleksa Sarai return -EXDEV; 86772ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 86872ba2929SAleksa Sarai /* Absolute path arguments to path_init() are allowed. */ 86972ba2929SAleksa Sarai if (nd->path.mnt != NULL && nd->path.mnt != nd->root.mnt) 87072ba2929SAleksa Sarai return -EXDEV; 87172ba2929SAleksa Sarai } 872740a1678SAleksa Sarai if (!nd->root.mnt) { 873740a1678SAleksa Sarai int error = set_root(nd); 874740a1678SAleksa Sarai if (error) 875740a1678SAleksa Sarai return error; 876740a1678SAleksa Sarai } 877248fb5b9SAl Viro if (nd->flags & LOOKUP_RCU) { 878248fb5b9SAl Viro struct dentry *d; 879248fb5b9SAl Viro nd->path = nd->root; 880248fb5b9SAl Viro d = nd->path.dentry; 881248fb5b9SAl Viro nd->inode = d->d_inode; 882248fb5b9SAl Viro nd->seq = nd->root_seq; 883248fb5b9SAl Viro if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) 884248fb5b9SAl Viro return -ECHILD; 885248fb5b9SAl Viro } else { 886248fb5b9SAl Viro path_put(&nd->path); 887248fb5b9SAl Viro nd->path = nd->root; 888248fb5b9SAl Viro path_get(&nd->path); 889248fb5b9SAl Viro nd->inode = nd->path.dentry->d_inode; 890248fb5b9SAl Viro } 891248fb5b9SAl Viro nd->flags |= LOOKUP_JUMPED; 892248fb5b9SAl Viro return 0; 893248fb5b9SAl Viro } 894248fb5b9SAl Viro 895b5fb63c1SChristoph Hellwig /* 8966b255391SAl Viro * Helper to directly jump to a known parsed path from ->get_link, 897b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 898b5fb63c1SChristoph Hellwig */ 8991bc82070SAleksa Sarai int nd_jump_link(struct path *path) 900b5fb63c1SChristoph Hellwig { 9014b99d499SAleksa Sarai int error = -ELOOP; 9026e77137bSAl Viro struct nameidata *nd = current->nameidata; 903b5fb63c1SChristoph Hellwig 9044b99d499SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_MAGICLINKS)) 9054b99d499SAleksa Sarai goto err; 9064b99d499SAleksa Sarai 90772ba2929SAleksa Sarai error = -EXDEV; 90872ba2929SAleksa Sarai if (unlikely(nd->flags & LOOKUP_NO_XDEV)) { 90972ba2929SAleksa Sarai if (nd->path.mnt != path->mnt) 91072ba2929SAleksa Sarai goto err; 91172ba2929SAleksa Sarai } 912adb21d2bSAleksa Sarai /* Not currently safe for scoped-lookups. */ 913adb21d2bSAleksa Sarai if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) 914adb21d2bSAleksa Sarai goto err; 91572ba2929SAleksa Sarai 9164b99d499SAleksa Sarai path_put(&nd->path); 917b5fb63c1SChristoph Hellwig nd->path = *path; 918b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 919b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 9201bc82070SAleksa Sarai return 0; 9214b99d499SAleksa Sarai 9224b99d499SAleksa Sarai err: 9234b99d499SAleksa Sarai path_put(path); 9244b99d499SAleksa Sarai return error; 925b5fb63c1SChristoph Hellwig } 926b5fb63c1SChristoph Hellwig 927b9ff4429SAl Viro static inline void put_link(struct nameidata *nd) 928574197e0SAl Viro { 92921c3003dSAl Viro struct saved *last = nd->stack + --nd->depth; 930fceef393SAl Viro do_delayed_call(&last->done); 9316548fae2SAl Viro if (!(nd->flags & LOOKUP_RCU)) 932b9ff4429SAl Viro path_put(&last->link); 933574197e0SAl Viro } 934574197e0SAl Viro 935561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 936561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 93730aba665SSalvatore Mesoraca int sysctl_protected_fifos __read_mostly; 93830aba665SSalvatore Mesoraca int sysctl_protected_regular __read_mostly; 939800179c9SKees Cook 940800179c9SKees Cook /** 941800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 94255852635SRandy Dunlap * @nd: nameidata pathwalk data 943800179c9SKees Cook * 944800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 945800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 946800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 947800179c9SKees Cook * processes from failing races against path names that may change out 948800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 949800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 950800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 951800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 952800179c9SKees Cook * 953800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 954800179c9SKees Cook */ 955ad6cc4c3SAl Viro static inline int may_follow_link(struct nameidata *nd, const struct inode *inode) 956800179c9SKees Cook { 957800179c9SKees Cook const struct inode *parent; 9582d7f9e2aSSeth Forshee kuid_t puid; 959800179c9SKees Cook 960800179c9SKees Cook if (!sysctl_protected_symlinks) 961800179c9SKees Cook return 0; 962800179c9SKees Cook 963800179c9SKees Cook /* Allowed if owner and follower match. */ 96481abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 965800179c9SKees Cook return 0; 966800179c9SKees Cook 967800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 968aa65fa35SAl Viro parent = nd->inode; 969800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 970800179c9SKees Cook return 0; 971800179c9SKees Cook 972800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 9732d7f9e2aSSeth Forshee puid = parent->i_uid; 9742d7f9e2aSSeth Forshee if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) 975800179c9SKees Cook return 0; 976800179c9SKees Cook 97731956502SAl Viro if (nd->flags & LOOKUP_RCU) 97831956502SAl Viro return -ECHILD; 97931956502SAl Viro 980ea841bafSRichard Guy Briggs audit_inode(nd->name, nd->stack[0].link.dentry, 0); 981245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "follow_link"); 982800179c9SKees Cook return -EACCES; 983800179c9SKees Cook } 984800179c9SKees Cook 985800179c9SKees Cook /** 986800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 987800179c9SKees Cook * @inode: the source inode to hardlink from 988800179c9SKees Cook * 989800179c9SKees Cook * Return false if at least one of the following conditions: 990800179c9SKees Cook * - inode is not a regular file 991800179c9SKees Cook * - inode is setuid 992800179c9SKees Cook * - inode is setgid and group-exec 993800179c9SKees Cook * - access failure for read and write 994800179c9SKees Cook * 995800179c9SKees Cook * Otherwise returns true. 996800179c9SKees Cook */ 997800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 998800179c9SKees Cook { 999800179c9SKees Cook umode_t mode = inode->i_mode; 1000800179c9SKees Cook 1001800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 1002800179c9SKees Cook if (!S_ISREG(mode)) 1003800179c9SKees Cook return false; 1004800179c9SKees Cook 1005800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 1006800179c9SKees Cook if (mode & S_ISUID) 1007800179c9SKees Cook return false; 1008800179c9SKees Cook 1009800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 1010800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 1011800179c9SKees Cook return false; 1012800179c9SKees Cook 1013800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 1014800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 1015800179c9SKees Cook return false; 1016800179c9SKees Cook 1017800179c9SKees Cook return true; 1018800179c9SKees Cook } 1019800179c9SKees Cook 1020800179c9SKees Cook /** 1021800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 1022800179c9SKees Cook * @link: the source to hardlink from 1023800179c9SKees Cook * 1024800179c9SKees Cook * Block hardlink when all of: 1025800179c9SKees Cook * - sysctl_protected_hardlinks enabled 1026800179c9SKees Cook * - fsuid does not match inode 1027800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 1028f2ca3796SDirk Steinmetz * - not CAP_FOWNER in a namespace with the inode owner uid mapped 1029800179c9SKees Cook * 1030800179c9SKees Cook * Returns 0 if successful, -ve on error. 1031800179c9SKees Cook */ 1032800179c9SKees Cook static int may_linkat(struct path *link) 1033800179c9SKees Cook { 1034593d1ce8SEric W. Biederman struct inode *inode = link->dentry->d_inode; 1035593d1ce8SEric W. Biederman 1036593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 1037593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 1038593d1ce8SEric W. Biederman return -EOVERFLOW; 1039800179c9SKees Cook 1040800179c9SKees Cook if (!sysctl_protected_hardlinks) 1041800179c9SKees Cook return 0; 1042800179c9SKees Cook 1043800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 1044800179c9SKees Cook * otherwise, it must be a safe source. 1045800179c9SKees Cook */ 1046cc658db4SKees Cook if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) 1047800179c9SKees Cook return 0; 1048800179c9SKees Cook 1049245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_LINK, "linkat"); 1050800179c9SKees Cook return -EPERM; 1051800179c9SKees Cook } 1052800179c9SKees Cook 105330aba665SSalvatore Mesoraca /** 105430aba665SSalvatore Mesoraca * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory 105530aba665SSalvatore Mesoraca * should be allowed, or not, on files that already 105630aba665SSalvatore Mesoraca * exist. 1057d0cb5018SAl Viro * @dir_mode: mode bits of directory 1058d0cb5018SAl Viro * @dir_uid: owner of directory 105930aba665SSalvatore Mesoraca * @inode: the inode of the file to open 106030aba665SSalvatore Mesoraca * 106130aba665SSalvatore Mesoraca * Block an O_CREAT open of a FIFO (or a regular file) when: 106230aba665SSalvatore Mesoraca * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled 106330aba665SSalvatore Mesoraca * - the file already exists 106430aba665SSalvatore Mesoraca * - we are in a sticky directory 106530aba665SSalvatore Mesoraca * - we don't own the file 106630aba665SSalvatore Mesoraca * - the owner of the directory doesn't own the file 106730aba665SSalvatore Mesoraca * - the directory is world writable 106830aba665SSalvatore Mesoraca * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 106930aba665SSalvatore Mesoraca * the directory doesn't have to be world writable: being group writable will 107030aba665SSalvatore Mesoraca * be enough. 107130aba665SSalvatore Mesoraca * 107230aba665SSalvatore Mesoraca * Returns 0 if the open is allowed, -ve on error. 107330aba665SSalvatore Mesoraca */ 1074d0cb5018SAl Viro static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, 107530aba665SSalvatore Mesoraca struct inode * const inode) 107630aba665SSalvatore Mesoraca { 107730aba665SSalvatore Mesoraca if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || 107830aba665SSalvatore Mesoraca (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || 1079d0cb5018SAl Viro likely(!(dir_mode & S_ISVTX)) || 1080d0cb5018SAl Viro uid_eq(inode->i_uid, dir_uid) || 108130aba665SSalvatore Mesoraca uid_eq(current_fsuid(), inode->i_uid)) 108230aba665SSalvatore Mesoraca return 0; 108330aba665SSalvatore Mesoraca 1084d0cb5018SAl Viro if (likely(dir_mode & 0002) || 1085d0cb5018SAl Viro (dir_mode & 0020 && 108630aba665SSalvatore Mesoraca ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || 108730aba665SSalvatore Mesoraca (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { 1088245d7369SKees Cook const char *operation = S_ISFIFO(inode->i_mode) ? 1089245d7369SKees Cook "sticky_create_fifo" : 1090245d7369SKees Cook "sticky_create_regular"; 1091245d7369SKees Cook audit_log_path_denied(AUDIT_ANOM_CREAT, operation); 109230aba665SSalvatore Mesoraca return -EACCES; 109330aba665SSalvatore Mesoraca } 109430aba665SSalvatore Mesoraca return 0; 109530aba665SSalvatore Mesoraca } 109630aba665SSalvatore Mesoraca 1097f015f126SDavid Howells /* 1098f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 1099f015f126SDavid Howells * 1100f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 1101f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 1102f015f126SDavid Howells * Up is towards /. 1103f015f126SDavid Howells * 1104f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 1105f015f126SDavid Howells * root. 1106f015f126SDavid Howells */ 1107bab77ebfSAl Viro int follow_up(struct path *path) 11081da177e4SLinus Torvalds { 11090714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 11100714a533SAl Viro struct mount *parent; 11111da177e4SLinus Torvalds struct dentry *mountpoint; 111299b7db7bSNick Piggin 111348a066e7SAl Viro read_seqlock_excl(&mount_lock); 11140714a533SAl Viro parent = mnt->mnt_parent; 11153c0a6163SAl Viro if (parent == mnt) { 111648a066e7SAl Viro read_sequnlock_excl(&mount_lock); 11171da177e4SLinus Torvalds return 0; 11181da177e4SLinus Torvalds } 11190714a533SAl Viro mntget(&parent->mnt); 1120a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 112148a066e7SAl Viro read_sequnlock_excl(&mount_lock); 1122bab77ebfSAl Viro dput(path->dentry); 1123bab77ebfSAl Viro path->dentry = mountpoint; 1124bab77ebfSAl Viro mntput(path->mnt); 11250714a533SAl Viro path->mnt = &parent->mnt; 11261da177e4SLinus Torvalds return 1; 11271da177e4SLinus Torvalds } 11284d359507SAl Viro EXPORT_SYMBOL(follow_up); 11291da177e4SLinus Torvalds 11307ef482faSAl Viro static bool choose_mountpoint_rcu(struct mount *m, const struct path *root, 11317ef482faSAl Viro struct path *path, unsigned *seqp) 11327ef482faSAl Viro { 11337ef482faSAl Viro while (mnt_has_parent(m)) { 11347ef482faSAl Viro struct dentry *mountpoint = m->mnt_mountpoint; 11357ef482faSAl Viro 11367ef482faSAl Viro m = m->mnt_parent; 11377ef482faSAl Viro if (unlikely(root->dentry == mountpoint && 11387ef482faSAl Viro root->mnt == &m->mnt)) 11397ef482faSAl Viro break; 11407ef482faSAl Viro if (mountpoint != m->mnt.mnt_root) { 11417ef482faSAl Viro path->mnt = &m->mnt; 11427ef482faSAl Viro path->dentry = mountpoint; 11437ef482faSAl Viro *seqp = read_seqcount_begin(&mountpoint->d_seq); 11447ef482faSAl Viro return true; 11457ef482faSAl Viro } 11467ef482faSAl Viro } 11477ef482faSAl Viro return false; 11487ef482faSAl Viro } 11497ef482faSAl Viro 11502aa38470SAl Viro static bool choose_mountpoint(struct mount *m, const struct path *root, 11512aa38470SAl Viro struct path *path) 11522aa38470SAl Viro { 11532aa38470SAl Viro bool found; 11542aa38470SAl Viro 11552aa38470SAl Viro rcu_read_lock(); 11562aa38470SAl Viro while (1) { 11572aa38470SAl Viro unsigned seq, mseq = read_seqbegin(&mount_lock); 11582aa38470SAl Viro 11592aa38470SAl Viro found = choose_mountpoint_rcu(m, root, path, &seq); 11602aa38470SAl Viro if (unlikely(!found)) { 11612aa38470SAl Viro if (!read_seqretry(&mount_lock, mseq)) 11622aa38470SAl Viro break; 11632aa38470SAl Viro } else { 11642aa38470SAl Viro if (likely(__legitimize_path(path, seq, mseq))) 11652aa38470SAl Viro break; 11662aa38470SAl Viro rcu_read_unlock(); 11672aa38470SAl Viro path_put(path); 11682aa38470SAl Viro rcu_read_lock(); 11692aa38470SAl Viro } 11702aa38470SAl Viro } 11712aa38470SAl Viro rcu_read_unlock(); 11722aa38470SAl Viro return found; 11732aa38470SAl Viro } 11742aa38470SAl Viro 1175b5c84bf6SNick Piggin /* 11769875cf80SDavid Howells * Perform an automount 11779875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 11789875cf80SDavid Howells * were called with. 11791da177e4SLinus Torvalds */ 11801c9f5e06SAl Viro static int follow_automount(struct path *path, int *count, unsigned lookup_flags) 118131e6b01fSNick Piggin { 118225e195aaSAl Viro struct dentry *dentry = path->dentry; 11839875cf80SDavid Howells 11840ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 11850ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 11860ec26fd0SMiklos Szeredi * the name. 11870ec26fd0SMiklos Szeredi * 11880ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 11895a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 11900ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 11910ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 11920ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 11930ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 11945a30d8a2SDavid Howells */ 11951c9f5e06SAl Viro if (!(lookup_flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 11965d38f049SIan Kent LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 119725e195aaSAl Viro dentry->d_inode) 11989875cf80SDavid Howells return -EISDIR; 11990ec26fd0SMiklos Szeredi 12001c9f5e06SAl Viro if (count && (*count)++ >= MAXSYMLINKS) 12019875cf80SDavid Howells return -ELOOP; 12029875cf80SDavid Howells 120325e195aaSAl Viro return finish_automount(dentry->d_op->d_automount(path), path); 1204ea5b778aSDavid Howells } 12059875cf80SDavid Howells 12069875cf80SDavid Howells /* 12079deed3ebSAl Viro * mount traversal - out-of-line part. One note on ->d_flags accesses - 12089deed3ebSAl Viro * dentries are pinned but not locked here, so negative dentry can go 12099deed3ebSAl Viro * positive right under us. Use of smp_load_acquire() provides a barrier 12109deed3ebSAl Viro * sufficient for ->d_inode and ->d_flags consistency. 12119875cf80SDavid Howells */ 12129deed3ebSAl Viro static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped, 12139deed3ebSAl Viro int *count, unsigned lookup_flags) 12149875cf80SDavid Howells { 12159deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 12169875cf80SDavid Howells bool need_mntput = false; 12178aef1884SAl Viro int ret = 0; 12189875cf80SDavid Howells 12199deed3ebSAl Viro while (flags & DCACHE_MANAGED_DENTRY) { 1220cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1221cc53ce53SDavid Howells * being held. */ 1222d41efb52SAl Viro if (flags & DCACHE_MANAGE_TRANSIT) { 1223fb5f51c7SIan Kent ret = path->dentry->d_op->d_manage(path, false); 1224508c8772SAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 1225cc53ce53SDavid Howells if (ret < 0) 12268aef1884SAl Viro break; 1227cc53ce53SDavid Howells } 1228cc53ce53SDavid Howells 12299deed3ebSAl Viro if (flags & DCACHE_MOUNTED) { // something's mounted on it.. 12309875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12319deed3ebSAl Viro if (mounted) { // ... in our namespace 12329875cf80SDavid Howells dput(path->dentry); 12339875cf80SDavid Howells if (need_mntput) 1234463ffb2eSAl Viro mntput(path->mnt); 1235463ffb2eSAl Viro path->mnt = mounted; 1236463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 12379deed3ebSAl Viro // here we know it's positive 12389deed3ebSAl Viro flags = path->dentry->d_flags; 12399875cf80SDavid Howells need_mntput = true; 12409875cf80SDavid Howells continue; 1241463ffb2eSAl Viro } 12421da177e4SLinus Torvalds } 12439875cf80SDavid Howells 12449deed3ebSAl Viro if (!(flags & DCACHE_NEED_AUTOMOUNT)) 12459deed3ebSAl Viro break; 12469deed3ebSAl Viro 12479deed3ebSAl Viro // uncovered automount point 12489deed3ebSAl Viro ret = follow_automount(path, count, lookup_flags); 12499deed3ebSAl Viro flags = smp_load_acquire(&path->dentry->d_flags); 12509875cf80SDavid Howells if (ret < 0) 12518aef1884SAl Viro break; 12529875cf80SDavid Howells } 12539875cf80SDavid Howells 12549deed3ebSAl Viro if (ret == -EISDIR) 12559deed3ebSAl Viro ret = 0; 12569deed3ebSAl Viro // possible if you race with several mount --move 12579deed3ebSAl Viro if (need_mntput && path->mnt == mnt) 12588aef1884SAl Viro mntput(path->mnt); 12599deed3ebSAl Viro if (!ret && unlikely(d_flags_negative(flags))) 1260d41efb52SAl Viro ret = -ENOENT; 12619deed3ebSAl Viro *jumped = need_mntput; 12628402752eSAl Viro return ret; 12631da177e4SLinus Torvalds } 12641da177e4SLinus Torvalds 12659deed3ebSAl Viro static inline int traverse_mounts(struct path *path, bool *jumped, 12669deed3ebSAl Viro int *count, unsigned lookup_flags) 12679deed3ebSAl Viro { 12689deed3ebSAl Viro unsigned flags = smp_load_acquire(&path->dentry->d_flags); 12699deed3ebSAl Viro 12709deed3ebSAl Viro /* fastpath */ 12719deed3ebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) { 12729deed3ebSAl Viro *jumped = false; 12739deed3ebSAl Viro if (unlikely(d_flags_negative(flags))) 12749deed3ebSAl Viro return -ENOENT; 12759deed3ebSAl Viro return 0; 12769deed3ebSAl Viro } 12779deed3ebSAl Viro return __traverse_mounts(path, flags, jumped, count, lookup_flags); 12789deed3ebSAl Viro } 12799deed3ebSAl Viro 1280cc53ce53SDavid Howells int follow_down_one(struct path *path) 12811da177e4SLinus Torvalds { 12821da177e4SLinus Torvalds struct vfsmount *mounted; 12831da177e4SLinus Torvalds 12841c755af4SAl Viro mounted = lookup_mnt(path); 12851da177e4SLinus Torvalds if (mounted) { 12869393bd07SAl Viro dput(path->dentry); 12879393bd07SAl Viro mntput(path->mnt); 12889393bd07SAl Viro path->mnt = mounted; 12899393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 12901da177e4SLinus Torvalds return 1; 12911da177e4SLinus Torvalds } 12921da177e4SLinus Torvalds return 0; 12931da177e4SLinus Torvalds } 12944d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 12951da177e4SLinus Torvalds 12969875cf80SDavid Howells /* 12979deed3ebSAl Viro * Follow down to the covering mount currently visible to userspace. At each 12989deed3ebSAl Viro * point, the filesystem owning that dentry may be queried as to whether the 12999deed3ebSAl Viro * caller is permitted to proceed or not. 13009deed3ebSAl Viro */ 13019deed3ebSAl Viro int follow_down(struct path *path) 13029deed3ebSAl Viro { 13039deed3ebSAl Viro struct vfsmount *mnt = path->mnt; 13049deed3ebSAl Viro bool jumped; 13059deed3ebSAl Viro int ret = traverse_mounts(path, &jumped, NULL, 0); 13069deed3ebSAl Viro 13079deed3ebSAl Viro if (path->mnt != mnt) 13089deed3ebSAl Viro mntput(mnt); 13099deed3ebSAl Viro return ret; 13109deed3ebSAl Viro } 13119deed3ebSAl Viro EXPORT_SYMBOL(follow_down); 13129deed3ebSAl Viro 13139deed3ebSAl Viro /* 1314287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1315287548e4SAl Viro * we meet a managed dentry that would need blocking. 13169875cf80SDavid Howells */ 13179875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1318254cf582SAl Viro struct inode **inode, unsigned *seqp) 13199875cf80SDavid Howells { 1320ea936aebSAl Viro struct dentry *dentry = path->dentry; 1321ea936aebSAl Viro unsigned int flags = dentry->d_flags; 1322ea936aebSAl Viro 1323ea936aebSAl Viro if (likely(!(flags & DCACHE_MANAGED_DENTRY))) 1324ea936aebSAl Viro return true; 1325ea936aebSAl Viro 1326ea936aebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1327ea936aebSAl Viro return false; 1328ea936aebSAl Viro 132962a7375eSIan Kent for (;;) { 133062a7375eSIan Kent /* 133162a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 133262a7375eSIan Kent * that wants to block transit. 133362a7375eSIan Kent */ 1334ea936aebSAl Viro if (unlikely(flags & DCACHE_MANAGE_TRANSIT)) { 1335ea936aebSAl Viro int res = dentry->d_op->d_manage(path, true); 1336ea936aebSAl Viro if (res) 1337ea936aebSAl Viro return res == -EISDIR; 1338ea936aebSAl Viro flags = dentry->d_flags; 1339b8faf035SNeilBrown } 134062a7375eSIan Kent 1341ea936aebSAl Viro if (flags & DCACHE_MOUNTED) { 1342ea936aebSAl Viro struct mount *mounted = __lookup_mnt(path->mnt, dentry); 1343ea936aebSAl Viro if (mounted) { 1344c7105365SAl Viro path->mnt = &mounted->mnt; 1345ea936aebSAl Viro dentry = path->dentry = mounted->mnt.mnt_root; 1346a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 1347ea936aebSAl Viro *seqp = read_seqcount_begin(&dentry->d_seq); 1348ea936aebSAl Viro *inode = dentry->d_inode; 134959430262SLinus Torvalds /* 1350ea936aebSAl Viro * We don't need to re-check ->d_seq after this 1351ea936aebSAl Viro * ->d_inode read - there will be an RCU delay 1352ea936aebSAl Viro * between mount hash removal and ->mnt_root 1353ea936aebSAl Viro * becoming unpinned. 135459430262SLinus Torvalds */ 1355ea936aebSAl Viro flags = dentry->d_flags; 1356ea936aebSAl Viro continue; 13579875cf80SDavid Howells } 1358ea936aebSAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1359ea936aebSAl Viro return false; 1360ea936aebSAl Viro } 1361ea936aebSAl Viro return !(flags & DCACHE_NEED_AUTOMOUNT); 1362ea936aebSAl Viro } 1363287548e4SAl Viro } 1364287548e4SAl Viro 1365db3c9adeSAl Viro static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry, 1366db3c9adeSAl Viro struct path *path, struct inode **inode, 1367db3c9adeSAl Viro unsigned int *seqp) 1368bd7c4b50SAl Viro { 13699deed3ebSAl Viro bool jumped; 1370db3c9adeSAl Viro int ret; 1371bd7c4b50SAl Viro 1372db3c9adeSAl Viro path->mnt = nd->path.mnt; 1373db3c9adeSAl Viro path->dentry = dentry; 1374c153007bSAl Viro if (nd->flags & LOOKUP_RCU) { 1375c153007bSAl Viro unsigned int seq = *seqp; 1376c153007bSAl Viro if (unlikely(!*inode)) 1377c153007bSAl Viro return -ENOENT; 1378c153007bSAl Viro if (likely(__follow_mount_rcu(nd, path, inode, seqp))) 13799deed3ebSAl Viro return 0; 1380c153007bSAl Viro if (unlazy_child(nd, dentry, seq)) 1381c153007bSAl Viro return -ECHILD; 1382c153007bSAl Viro // *path might've been clobbered by __follow_mount_rcu() 1383c153007bSAl Viro path->mnt = nd->path.mnt; 1384c153007bSAl Viro path->dentry = dentry; 1385c153007bSAl Viro } 13869deed3ebSAl Viro ret = traverse_mounts(path, &jumped, &nd->total_link_count, nd->flags); 13879deed3ebSAl Viro if (jumped) { 13889deed3ebSAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 13899deed3ebSAl Viro ret = -EXDEV; 13909deed3ebSAl Viro else 13919deed3ebSAl Viro nd->flags |= LOOKUP_JUMPED; 13929deed3ebSAl Viro } 13939deed3ebSAl Viro if (unlikely(ret)) { 13949deed3ebSAl Viro dput(path->dentry); 13959deed3ebSAl Viro if (path->mnt != nd->path.mnt) 13969deed3ebSAl Viro mntput(path->mnt); 13979deed3ebSAl Viro } else { 1398bd7c4b50SAl Viro *inode = d_backing_inode(path->dentry); 1399bd7c4b50SAl Viro *seqp = 0; /* out of RCU mode, so the value doesn't matter */ 1400bd7c4b50SAl Viro } 1401bd7c4b50SAl Viro return ret; 1402bd7c4b50SAl Viro } 1403bd7c4b50SAl Viro 14049875cf80SDavid Howells /* 1405f4fdace9SOleg Drokin * This looks up the name in dcache and possibly revalidates the found dentry. 1406f4fdace9SOleg Drokin * NULL is returned if the dentry does not exist in the cache. 1407baa03890SNick Piggin */ 1408e3c13928SAl Viro static struct dentry *lookup_dcache(const struct qstr *name, 1409e3c13928SAl Viro struct dentry *dir, 14106c51e513SAl Viro unsigned int flags) 1411baa03890SNick Piggin { 1412a89f8337SAl Viro struct dentry *dentry = d_lookup(dir, name); 1413bad61189SMiklos Szeredi if (dentry) { 1414a89f8337SAl Viro int error = d_revalidate(dentry, flags); 1415bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 141674ff0ffcSAl Viro if (!error) 14175542aa2fSEric W. Biederman d_invalidate(dentry); 1418bad61189SMiklos Szeredi dput(dentry); 141974ff0ffcSAl Viro return ERR_PTR(error); 1420bad61189SMiklos Szeredi } 1421bad61189SMiklos Szeredi } 1422baa03890SNick Piggin return dentry; 1423baa03890SNick Piggin } 1424baa03890SNick Piggin 1425baa03890SNick Piggin /* 1426a03ece5fSAl Viro * Parent directory has inode locked exclusive. This is one 1427a03ece5fSAl Viro * and only case when ->lookup() gets called on non in-lookup 1428a03ece5fSAl Viro * dentries - as the matter of fact, this only gets called 1429a03ece5fSAl Viro * when directory is guaranteed to have no in-lookup children 1430a03ece5fSAl Viro * at all. 143144396f4bSJosef Bacik */ 1432a03ece5fSAl Viro static struct dentry *__lookup_hash(const struct qstr *name, 1433a03ece5fSAl Viro struct dentry *base, unsigned int flags) 143444396f4bSJosef Bacik { 1435a03ece5fSAl Viro struct dentry *dentry = lookup_dcache(name, base, flags); 143644396f4bSJosef Bacik struct dentry *old; 1437a03ece5fSAl Viro struct inode *dir = base->d_inode; 1438a03ece5fSAl Viro 1439a03ece5fSAl Viro if (dentry) 1440a03ece5fSAl Viro return dentry; 144144396f4bSJosef Bacik 144244396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1443a03ece5fSAl Viro if (unlikely(IS_DEADDIR(dir))) 144444396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1445a03ece5fSAl Viro 1446a03ece5fSAl Viro dentry = d_alloc(base, name); 1447a03ece5fSAl Viro if (unlikely(!dentry)) 1448a03ece5fSAl Viro return ERR_PTR(-ENOMEM); 144944396f4bSJosef Bacik 145072bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 145144396f4bSJosef Bacik if (unlikely(old)) { 145244396f4bSJosef Bacik dput(dentry); 145344396f4bSJosef Bacik dentry = old; 145444396f4bSJosef Bacik } 145544396f4bSJosef Bacik return dentry; 145644396f4bSJosef Bacik } 145744396f4bSJosef Bacik 145820e34357SAl Viro static struct dentry *lookup_fast(struct nameidata *nd, 145920e34357SAl Viro struct inode **inode, 1460254cf582SAl Viro unsigned *seqp) 14611da177e4SLinus Torvalds { 146231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 14635a18fff2SAl Viro int status = 1; 14649875cf80SDavid Howells 14653cac260aSAl Viro /* 1466b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 14675d0f49c1SAl Viro * of a false negative due to a concurrent rename, the caller is 14685d0f49c1SAl Viro * going to fall back to non-racy lookup. 1469b04f784eSNick Piggin */ 147031e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 147131e6b01fSNick Piggin unsigned seq; 1472da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 14735d0f49c1SAl Viro if (unlikely(!dentry)) { 14744675ac39SAl Viro if (unlazy_walk(nd)) 147520e34357SAl Viro return ERR_PTR(-ECHILD); 147620e34357SAl Viro return NULL; 14775d0f49c1SAl Viro } 14785a18fff2SAl Viro 147912f8ad4bSLinus Torvalds /* 148012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 148112f8ad4bSLinus Torvalds * the dentry name information from lookup. 148212f8ad4bSLinus Torvalds */ 148363afdfc7SDavid Howells *inode = d_backing_inode(dentry); 14845d0f49c1SAl Viro if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) 148520e34357SAl Viro return ERR_PTR(-ECHILD); 148612f8ad4bSLinus Torvalds 148712f8ad4bSLinus Torvalds /* 148812f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 148912f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 149012f8ad4bSLinus Torvalds * 149112f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 149212f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 149312f8ad4bSLinus Torvalds */ 14945d0f49c1SAl Viro if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) 149520e34357SAl Viro return ERR_PTR(-ECHILD); 14965a18fff2SAl Viro 1497254cf582SAl Viro *seqp = seq; 14984ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 1499c153007bSAl Viro if (likely(status > 0)) 150020e34357SAl Viro return dentry; 15014675ac39SAl Viro if (unlazy_child(nd, dentry, seq)) 150220e34357SAl Viro return ERR_PTR(-ECHILD); 1503209a7fb2SAl Viro if (unlikely(status == -ECHILD)) 1504209a7fb2SAl Viro /* we'd been told to redo it in non-rcu mode */ 1505209a7fb2SAl Viro status = d_revalidate(dentry, nd->flags); 15065a18fff2SAl Viro } else { 1507e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 150881e6f520SAl Viro if (unlikely(!dentry)) 150920e34357SAl Viro return NULL; 15104ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 15115d0f49c1SAl Viro } 15125a18fff2SAl Viro if (unlikely(status <= 0)) { 1513e9742b53SAl Viro if (!status) 15145d0f49c1SAl Viro d_invalidate(dentry); 15155a18fff2SAl Viro dput(dentry); 151620e34357SAl Viro return ERR_PTR(status); 15175a18fff2SAl Viro } 151820e34357SAl Viro return dentry; 1519697f514dSMiklos Szeredi } 1520697f514dSMiklos Szeredi 1521697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 152288d8331aSAl Viro static struct dentry *__lookup_slow(const struct qstr *name, 1523e3c13928SAl Viro struct dentry *dir, 1524e3c13928SAl Viro unsigned int flags) 1525697f514dSMiklos Szeredi { 152688d8331aSAl Viro struct dentry *dentry, *old; 15271936386eSAl Viro struct inode *inode = dir->d_inode; 1528d9171b93SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 15291936386eSAl Viro 15301936386eSAl Viro /* Don't go there if it's already dead */ 153194bdd655SAl Viro if (unlikely(IS_DEADDIR(inode))) 153288d8331aSAl Viro return ERR_PTR(-ENOENT); 153394bdd655SAl Viro again: 1534d9171b93SAl Viro dentry = d_alloc_parallel(dir, name, &wq); 153594bdd655SAl Viro if (IS_ERR(dentry)) 153688d8331aSAl Viro return dentry; 153794bdd655SAl Viro if (unlikely(!d_in_lookup(dentry))) { 1538949a852eSAl Viro int error = d_revalidate(dentry, flags); 1539949a852eSAl Viro if (unlikely(error <= 0)) { 154094bdd655SAl Viro if (!error) { 1541949a852eSAl Viro d_invalidate(dentry); 1542949a852eSAl Viro dput(dentry); 154394bdd655SAl Viro goto again; 154494bdd655SAl Viro } 154594bdd655SAl Viro dput(dentry); 1546949a852eSAl Viro dentry = ERR_PTR(error); 1547949a852eSAl Viro } 154894bdd655SAl Viro } else { 15491936386eSAl Viro old = inode->i_op->lookup(inode, dentry, flags); 155085c7f810SAl Viro d_lookup_done(dentry); 15511936386eSAl Viro if (unlikely(old)) { 15521936386eSAl Viro dput(dentry); 15531936386eSAl Viro dentry = old; 1554949a852eSAl Viro } 1555949a852eSAl Viro } 1556e3c13928SAl Viro return dentry; 15571da177e4SLinus Torvalds } 15581da177e4SLinus Torvalds 155988d8331aSAl Viro static struct dentry *lookup_slow(const struct qstr *name, 156088d8331aSAl Viro struct dentry *dir, 156188d8331aSAl Viro unsigned int flags) 156288d8331aSAl Viro { 156388d8331aSAl Viro struct inode *inode = dir->d_inode; 156488d8331aSAl Viro struct dentry *res; 156588d8331aSAl Viro inode_lock_shared(inode); 156688d8331aSAl Viro res = __lookup_slow(name, dir, flags); 156788d8331aSAl Viro inode_unlock_shared(inode); 156888d8331aSAl Viro return res; 156988d8331aSAl Viro } 157088d8331aSAl Viro 157152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 157252094c8aSAl Viro { 157352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 15744ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 157552094c8aSAl Viro if (err != -ECHILD) 157652094c8aSAl Viro return err; 15774675ac39SAl Viro if (unlazy_walk(nd)) 157852094c8aSAl Viro return -ECHILD; 157952094c8aSAl Viro } 15804ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 158152094c8aSAl Viro } 158252094c8aSAl Viro 158349055906SAl Viro static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq) 1584d63ff28fSAl Viro { 1585ad6cc4c3SAl Viro int error; 1586ad6cc4c3SAl Viro 158749055906SAl Viro if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) 158849055906SAl Viro return -ELOOP; 1589626de996SAl Viro error = nd_alloc_stack(nd); 159049055906SAl Viro if (likely(!error)) 159149055906SAl Viro return 0; 1592bc40aee0SAl Viro if (error == -ECHILD) { 1593aef9404dSAl Viro // we must grab link first 1594aef9404dSAl Viro bool grabbed_link = legitimize_path(nd, link, seq); 1595aef9404dSAl Viro // ... and we must unlazy to be able to clean up 1596aef9404dSAl Viro error = unlazy_walk(nd); 1597aef9404dSAl Viro if (unlikely(!grabbed_link)) 1598aef9404dSAl Viro error = -ECHILD; 1599aef9404dSAl Viro if (!error) 1600bc40aee0SAl Viro error = nd_alloc_stack(nd); 1601bc40aee0SAl Viro } 160249055906SAl Viro return error; 160349055906SAl Viro } 160449055906SAl Viro 160549055906SAl Viro enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4}; 160649055906SAl Viro 160749055906SAl Viro static const char *pick_link(struct nameidata *nd, struct path *link, 160849055906SAl Viro struct inode *inode, unsigned seq, int flags) 160949055906SAl Viro { 161049055906SAl Viro struct saved *last; 161149055906SAl Viro const char *res; 161249055906SAl Viro int error = reserve_stack(nd, link, seq); 161349055906SAl Viro 161449055906SAl Viro if (unlikely(error)) { 161549055906SAl Viro if (!(nd->flags & LOOKUP_RCU)) 1616cd179f44SAl Viro path_put(link); 161706708adbSAl Viro return ERR_PTR(error); 1618626de996SAl Viro } 1619ab104923SAl Viro last = nd->stack + nd->depth++; 16201cf2665bSAl Viro last->link = *link; 1621fceef393SAl Viro clear_delayed_call(&last->done); 16220450b2d1SAl Viro last->seq = seq; 1623ad6cc4c3SAl Viro 1624b1a81972SAl Viro if (flags & WALK_TRAILING) { 1625ad6cc4c3SAl Viro error = may_follow_link(nd, inode); 1626ad6cc4c3SAl Viro if (unlikely(error)) 1627ad6cc4c3SAl Viro return ERR_PTR(error); 1628ad6cc4c3SAl Viro } 1629ad6cc4c3SAl Viro 1630ad6cc4c3SAl Viro if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS)) 1631ad6cc4c3SAl Viro return ERR_PTR(-ELOOP); 1632ad6cc4c3SAl Viro 1633ad6cc4c3SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1634ad6cc4c3SAl Viro touch_atime(&last->link); 1635ad6cc4c3SAl Viro cond_resched(); 1636ad6cc4c3SAl Viro } else if (atime_needs_update(&last->link, inode)) { 1637ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1638ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1639ad6cc4c3SAl Viro touch_atime(&last->link); 1640ad6cc4c3SAl Viro } 1641ad6cc4c3SAl Viro 1642ad6cc4c3SAl Viro error = security_inode_follow_link(link->dentry, inode, 1643ad6cc4c3SAl Viro nd->flags & LOOKUP_RCU); 1644ad6cc4c3SAl Viro if (unlikely(error)) 1645ad6cc4c3SAl Viro return ERR_PTR(error); 1646ad6cc4c3SAl Viro 1647ad6cc4c3SAl Viro res = READ_ONCE(inode->i_link); 1648ad6cc4c3SAl Viro if (!res) { 1649ad6cc4c3SAl Viro const char * (*get)(struct dentry *, struct inode *, 1650ad6cc4c3SAl Viro struct delayed_call *); 1651ad6cc4c3SAl Viro get = inode->i_op->get_link; 1652ad6cc4c3SAl Viro if (nd->flags & LOOKUP_RCU) { 1653ad6cc4c3SAl Viro res = get(NULL, inode, &last->done); 1654ad6cc4c3SAl Viro if (res == ERR_PTR(-ECHILD)) { 1655ad6cc4c3SAl Viro if (unlikely(unlazy_walk(nd))) 1656ad6cc4c3SAl Viro return ERR_PTR(-ECHILD); 1657ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1658ad6cc4c3SAl Viro } 1659ad6cc4c3SAl Viro } else { 1660ad6cc4c3SAl Viro res = get(link->dentry, inode, &last->done); 1661ad6cc4c3SAl Viro } 1662ad6cc4c3SAl Viro if (!res) 1663ad6cc4c3SAl Viro goto all_done; 1664ad6cc4c3SAl Viro if (IS_ERR(res)) 1665ad6cc4c3SAl Viro return res; 1666ad6cc4c3SAl Viro } 1667ad6cc4c3SAl Viro if (*res == '/') { 1668ad6cc4c3SAl Viro error = nd_jump_root(nd); 1669ad6cc4c3SAl Viro if (unlikely(error)) 1670ad6cc4c3SAl Viro return ERR_PTR(error); 1671ad6cc4c3SAl Viro while (unlikely(*++res == '/')) 1672ad6cc4c3SAl Viro ; 1673ad6cc4c3SAl Viro } 1674ad6cc4c3SAl Viro if (*res) 1675ad6cc4c3SAl Viro return res; 1676ad6cc4c3SAl Viro all_done: // pure jump 1677ad6cc4c3SAl Viro put_link(nd); 1678ad6cc4c3SAl Viro return NULL; 1679d63ff28fSAl Viro } 1680d63ff28fSAl Viro 16813ddcd056SLinus Torvalds /* 16823ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 16833ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 16843ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 16853ddcd056SLinus Torvalds * for the common case. 16863ddcd056SLinus Torvalds */ 1687b0417d2cSAl Viro static const char *step_into(struct nameidata *nd, int flags, 1688cbae4d12SAl Viro struct dentry *dentry, struct inode *inode, unsigned seq) 16893ddcd056SLinus Torvalds { 1690cbae4d12SAl Viro struct path path; 1691cbae4d12SAl Viro int err = handle_mounts(nd, dentry, &path, &inode, &seq); 1692cbae4d12SAl Viro 1693cbae4d12SAl Viro if (err < 0) 1694b0417d2cSAl Viro return ERR_PTR(err); 1695cbae4d12SAl Viro if (likely(!d_is_symlink(path.dentry)) || 16968c4efe22SAl Viro ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) || 1697aca2903eSAl Viro (flags & WALK_NOFOLLOW)) { 16988f64fb1cSAl Viro /* not a symlink or should not follow */ 1699c99687a0SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1700c99687a0SAl Viro dput(nd->path.dentry); 1701c99687a0SAl Viro if (nd->path.mnt != path.mnt) 1702c99687a0SAl Viro mntput(nd->path.mnt); 1703c99687a0SAl Viro } 1704c99687a0SAl Viro nd->path = path; 17058f64fb1cSAl Viro nd->inode = inode; 17068f64fb1cSAl Viro nd->seq = seq; 1707b0417d2cSAl Viro return NULL; 17088f64fb1cSAl Viro } 1709a7f77542SAl Viro if (nd->flags & LOOKUP_RCU) { 171084f0cd9eSAl Viro /* make sure that d_is_symlink above matches inode */ 1711cbae4d12SAl Viro if (read_seqcount_retry(&path.dentry->d_seq, seq)) 1712b0417d2cSAl Viro return ERR_PTR(-ECHILD); 171384f0cd9eSAl Viro } else { 171484f0cd9eSAl Viro if (path.mnt == nd->path.mnt) 171584f0cd9eSAl Viro mntget(path.mnt); 1716a7f77542SAl Viro } 1717b1a81972SAl Viro return pick_link(nd, &path, inode, seq, flags); 17183ddcd056SLinus Torvalds } 17193ddcd056SLinus Torvalds 1720c2df1968SAl Viro static struct dentry *follow_dotdot_rcu(struct nameidata *nd, 1721c2df1968SAl Viro struct inode **inodep, 1722c2df1968SAl Viro unsigned *seqp) 1723957dd41dSAl Viro { 172412487f30SAl Viro struct dentry *parent, *old; 1725957dd41dSAl Viro 172612487f30SAl Viro if (path_equal(&nd->path, &nd->root)) 172712487f30SAl Viro goto in_root; 172812487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17297ef482faSAl Viro struct path path; 1730efe772d6SAl Viro unsigned seq; 17317ef482faSAl Viro if (!choose_mountpoint_rcu(real_mount(nd->path.mnt), 17327ef482faSAl Viro &nd->root, &path, &seq)) 173312487f30SAl Viro goto in_root; 1734efe772d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1735efe772d6SAl Viro return ERR_PTR(-ECHILD); 1736efe772d6SAl Viro nd->path = path; 1737efe772d6SAl Viro nd->inode = path.dentry->d_inode; 1738efe772d6SAl Viro nd->seq = seq; 1739efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1740efe772d6SAl Viro return ERR_PTR(-ECHILD); 1741efe772d6SAl Viro /* we know that mountpoint was pinned */ 1742957dd41dSAl Viro } 174312487f30SAl Viro old = nd->path.dentry; 174412487f30SAl Viro parent = old->d_parent; 174512487f30SAl Viro *inodep = parent->d_inode; 174612487f30SAl Viro *seqp = read_seqcount_begin(&parent->d_seq); 174712487f30SAl Viro if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) 174812487f30SAl Viro return ERR_PTR(-ECHILD); 174912487f30SAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) 175012487f30SAl Viro return ERR_PTR(-ECHILD); 175112487f30SAl Viro return parent; 175212487f30SAl Viro in_root: 1753efe772d6SAl Viro if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) 1754efe772d6SAl Viro return ERR_PTR(-ECHILD); 1755957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17567521f22bSAl Viro return ERR_PTR(-ECHILD); 1757c2df1968SAl Viro return NULL; 1758957dd41dSAl Viro } 1759957dd41dSAl Viro 1760c2df1968SAl Viro static struct dentry *follow_dotdot(struct nameidata *nd, 1761c2df1968SAl Viro struct inode **inodep, 1762c2df1968SAl Viro unsigned *seqp) 1763957dd41dSAl Viro { 176412487f30SAl Viro struct dentry *parent; 176512487f30SAl Viro 1766957dd41dSAl Viro if (path_equal(&nd->path, &nd->root)) 176712487f30SAl Viro goto in_root; 176812487f30SAl Viro if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) { 17692aa38470SAl Viro struct path path; 17702aa38470SAl Viro 17712aa38470SAl Viro if (!choose_mountpoint(real_mount(nd->path.mnt), 17722aa38470SAl Viro &nd->root, &path)) 177312487f30SAl Viro goto in_root; 1774165200d6SAl Viro path_put(&nd->path); 1775165200d6SAl Viro nd->path = path; 17762aa38470SAl Viro nd->inode = path.dentry->d_inode; 1777165200d6SAl Viro if (unlikely(nd->flags & LOOKUP_NO_XDEV)) 1778165200d6SAl Viro return ERR_PTR(-EXDEV); 177912487f30SAl Viro } 1780957dd41dSAl Viro /* rare case of legitimate dget_parent()... */ 178112487f30SAl Viro parent = dget_parent(nd->path.dentry); 1782957dd41dSAl Viro if (unlikely(!path_connected(nd->path.mnt, parent))) { 1783957dd41dSAl Viro dput(parent); 17847521f22bSAl Viro return ERR_PTR(-ENOENT); 1785957dd41dSAl Viro } 1786c2df1968SAl Viro *seqp = 0; 1787c2df1968SAl Viro *inodep = parent->d_inode; 1788c2df1968SAl Viro return parent; 178912487f30SAl Viro 179012487f30SAl Viro in_root: 1791957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_BENEATH)) 17927521f22bSAl Viro return ERR_PTR(-EXDEV); 1793c2df1968SAl Viro dget(nd->path.dentry); 1794c2df1968SAl Viro return NULL; 1795957dd41dSAl Viro } 1796957dd41dSAl Viro 17977521f22bSAl Viro static const char *handle_dots(struct nameidata *nd, int type) 1798957dd41dSAl Viro { 1799957dd41dSAl Viro if (type == LAST_DOTDOT) { 18007521f22bSAl Viro const char *error = NULL; 1801c2df1968SAl Viro struct dentry *parent; 1802c2df1968SAl Viro struct inode *inode; 1803c2df1968SAl Viro unsigned seq; 1804957dd41dSAl Viro 1805957dd41dSAl Viro if (!nd->root.mnt) { 18067521f22bSAl Viro error = ERR_PTR(set_root(nd)); 1807957dd41dSAl Viro if (error) 1808957dd41dSAl Viro return error; 1809957dd41dSAl Viro } 1810957dd41dSAl Viro if (nd->flags & LOOKUP_RCU) 1811c2df1968SAl Viro parent = follow_dotdot_rcu(nd, &inode, &seq); 1812957dd41dSAl Viro else 1813c2df1968SAl Viro parent = follow_dotdot(nd, &inode, &seq); 1814c2df1968SAl Viro if (IS_ERR(parent)) 1815c2df1968SAl Viro return ERR_CAST(parent); 1816c2df1968SAl Viro if (unlikely(!parent)) 1817c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1818c2df1968SAl Viro nd->path.dentry, nd->inode, nd->seq); 1819c2df1968SAl Viro else 1820c2df1968SAl Viro error = step_into(nd, WALK_NOFOLLOW, 1821c2df1968SAl Viro parent, inode, seq); 1822c2df1968SAl Viro if (unlikely(error)) 1823957dd41dSAl Viro return error; 1824957dd41dSAl Viro 1825957dd41dSAl Viro if (unlikely(nd->flags & LOOKUP_IS_SCOPED)) { 1826957dd41dSAl Viro /* 1827957dd41dSAl Viro * If there was a racing rename or mount along our 1828957dd41dSAl Viro * path, then we can't be sure that ".." hasn't jumped 1829957dd41dSAl Viro * above nd->root (and so userspace should retry or use 1830957dd41dSAl Viro * some fallback). 1831957dd41dSAl Viro */ 1832957dd41dSAl Viro smp_rmb(); 1833957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&mount_lock.seqcount, nd->m_seq))) 18347521f22bSAl Viro return ERR_PTR(-EAGAIN); 1835957dd41dSAl Viro if (unlikely(__read_seqcount_retry(&rename_lock.seqcount, nd->r_seq))) 18367521f22bSAl Viro return ERR_PTR(-EAGAIN); 1837957dd41dSAl Viro } 1838957dd41dSAl Viro } 18397521f22bSAl Viro return NULL; 1840957dd41dSAl Viro } 1841957dd41dSAl Viro 184292d27016SAl Viro static const char *walk_component(struct nameidata *nd, int flags) 1843ce57dfc1SAl Viro { 1844db3c9adeSAl Viro struct dentry *dentry; 1845ce57dfc1SAl Viro struct inode *inode; 1846254cf582SAl Viro unsigned seq; 1847ce57dfc1SAl Viro /* 1848ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1849ce57dfc1SAl Viro * to be able to know about the current root directory and 1850ce57dfc1SAl Viro * parent relationships. 1851ce57dfc1SAl Viro */ 18524693a547SAl Viro if (unlikely(nd->last_type != LAST_NORM)) { 18531c4ff1a8SAl Viro if (!(flags & WALK_MORE) && nd->depth) 18544693a547SAl Viro put_link(nd); 18557521f22bSAl Viro return handle_dots(nd, nd->last_type); 18564693a547SAl Viro } 185720e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 185820e34357SAl Viro if (IS_ERR(dentry)) 185992d27016SAl Viro return ERR_CAST(dentry); 186020e34357SAl Viro if (unlikely(!dentry)) { 1861db3c9adeSAl Viro dentry = lookup_slow(&nd->last, nd->path.dentry, nd->flags); 1862db3c9adeSAl Viro if (IS_ERR(dentry)) 186392d27016SAl Viro return ERR_CAST(dentry); 186420e34357SAl Viro } 186556676ec3SAl Viro if (!(flags & WALK_MORE) && nd->depth) 186656676ec3SAl Viro put_link(nd); 1867b0417d2cSAl Viro return step_into(nd, flags, dentry, inode, seq); 1868ce57dfc1SAl Viro } 1869ce57dfc1SAl Viro 18701da177e4SLinus Torvalds /* 1871bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1872bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1873bfcfaa77SLinus Torvalds * 1874bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1875bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1876bfcfaa77SLinus Torvalds * fast. 1877bfcfaa77SLinus Torvalds * 1878bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1879bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1880bfcfaa77SLinus Torvalds * crossing operation. 1881bfcfaa77SLinus Torvalds * 1882bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1883bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1884bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1885bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1886bfcfaa77SLinus Torvalds */ 1887bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1888bfcfaa77SLinus Torvalds 1889f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1890bfcfaa77SLinus Torvalds 1891468a9428SGeorge Spelvin #ifdef HASH_MIX 1892bfcfaa77SLinus Torvalds 1893468a9428SGeorge Spelvin /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ 1894468a9428SGeorge Spelvin 1895468a9428SGeorge Spelvin #elif defined(CONFIG_64BIT) 18962a18da7aSGeorge Spelvin /* 18972a18da7aSGeorge Spelvin * Register pressure in the mixing function is an issue, particularly 18982a18da7aSGeorge Spelvin * on 32-bit x86, but almost any function requires one state value and 18992a18da7aSGeorge Spelvin * one temporary. Instead, use a function designed for two state values 19002a18da7aSGeorge Spelvin * and no temporaries. 19012a18da7aSGeorge Spelvin * 19022a18da7aSGeorge Spelvin * This function cannot create a collision in only two iterations, so 19032a18da7aSGeorge Spelvin * we have two iterations to achieve avalanche. In those two iterations, 19042a18da7aSGeorge Spelvin * we have six layers of mixing, which is enough to spread one bit's 19052a18da7aSGeorge Spelvin * influence out to 2^6 = 64 state bits. 19062a18da7aSGeorge Spelvin * 19072a18da7aSGeorge Spelvin * Rotate constants are scored by considering either 64 one-bit input 19082a18da7aSGeorge Spelvin * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the 19092a18da7aSGeorge Spelvin * probability of that delta causing a change to each of the 128 output 19102a18da7aSGeorge Spelvin * bits, using a sample of random initial states. 19112a18da7aSGeorge Spelvin * 19122a18da7aSGeorge Spelvin * The Shannon entropy of the computed probabilities is then summed 19132a18da7aSGeorge Spelvin * to produce a score. Ideally, any input change has a 50% chance of 19142a18da7aSGeorge Spelvin * toggling any given output bit. 19152a18da7aSGeorge Spelvin * 19162a18da7aSGeorge Spelvin * Mixing scores (in bits) for (12,45): 19172a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19182a18da7aSGeorge Spelvin * 1 round: 713.3 42542.6 19192a18da7aSGeorge Spelvin * 2 rounds: 2753.7 140389.8 19202a18da7aSGeorge Spelvin * 3 rounds: 5954.1 233458.2 19212a18da7aSGeorge Spelvin * 4 rounds: 7862.6 256672.2 19222a18da7aSGeorge Spelvin * Perfect: 8192 258048 19232a18da7aSGeorge Spelvin * (64*128) (64*63/2 * 128) 19242a18da7aSGeorge Spelvin */ 19252a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19262a18da7aSGeorge Spelvin ( x ^= (a), \ 19272a18da7aSGeorge Spelvin y ^= x, x = rol64(x,12),\ 19282a18da7aSGeorge Spelvin x += y, y = rol64(y,45),\ 19292a18da7aSGeorge Spelvin y *= 9 ) 1930bfcfaa77SLinus Torvalds 19310fed3ac8SGeorge Spelvin /* 19322a18da7aSGeorge Spelvin * Fold two longs into one 32-bit hash value. This must be fast, but 19332a18da7aSGeorge Spelvin * latency isn't quite as critical, as there is a fair bit of additional 19342a18da7aSGeorge Spelvin * work done before the hash value is used. 19350fed3ac8SGeorge Spelvin */ 19362a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19370fed3ac8SGeorge Spelvin { 19382a18da7aSGeorge Spelvin y ^= x * GOLDEN_RATIO_64; 19392a18da7aSGeorge Spelvin y *= GOLDEN_RATIO_64; 19402a18da7aSGeorge Spelvin return y >> 32; 19410fed3ac8SGeorge Spelvin } 19420fed3ac8SGeorge Spelvin 1943bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1944bfcfaa77SLinus Torvalds 19452a18da7aSGeorge Spelvin /* 19462a18da7aSGeorge Spelvin * Mixing scores (in bits) for (7,20): 19472a18da7aSGeorge Spelvin * Input delta: 1-bit 2-bit 19482a18da7aSGeorge Spelvin * 1 round: 330.3 9201.6 19492a18da7aSGeorge Spelvin * 2 rounds: 1246.4 25475.4 19502a18da7aSGeorge Spelvin * 3 rounds: 1907.1 31295.1 19512a18da7aSGeorge Spelvin * 4 rounds: 2042.3 31718.6 19522a18da7aSGeorge Spelvin * Perfect: 2048 31744 19532a18da7aSGeorge Spelvin * (32*64) (32*31/2 * 64) 19542a18da7aSGeorge Spelvin */ 19552a18da7aSGeorge Spelvin #define HASH_MIX(x, y, a) \ 19562a18da7aSGeorge Spelvin ( x ^= (a), \ 19572a18da7aSGeorge Spelvin y ^= x, x = rol32(x, 7),\ 19582a18da7aSGeorge Spelvin x += y, y = rol32(y,20),\ 19592a18da7aSGeorge Spelvin y *= 9 ) 1960bfcfaa77SLinus Torvalds 19612a18da7aSGeorge Spelvin static inline unsigned int fold_hash(unsigned long x, unsigned long y) 19620fed3ac8SGeorge Spelvin { 19632a18da7aSGeorge Spelvin /* Use arch-optimized multiply if one exists */ 19642a18da7aSGeorge Spelvin return __hash_32(y ^ __hash_32(x)); 19650fed3ac8SGeorge Spelvin } 19660fed3ac8SGeorge Spelvin 1967bfcfaa77SLinus Torvalds #endif 1968bfcfaa77SLinus Torvalds 19692a18da7aSGeorge Spelvin /* 19702a18da7aSGeorge Spelvin * Return the hash of a string of known length. This is carfully 19712a18da7aSGeorge Spelvin * designed to match hash_name(), which is the more critical function. 19722a18da7aSGeorge Spelvin * In particular, we must end by hashing a final word containing 0..7 19732a18da7aSGeorge Spelvin * payload bytes, to match the way that hash_name() iterates until it 19742a18da7aSGeorge Spelvin * finds the delimiter after the name. 19752a18da7aSGeorge Spelvin */ 19768387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 1977bfcfaa77SLinus Torvalds { 19788387ff25SLinus Torvalds unsigned long a, x = 0, y = (unsigned long)salt; 1979bfcfaa77SLinus Torvalds 1980bfcfaa77SLinus Torvalds for (;;) { 1981fcfd2fbfSGeorge Spelvin if (!len) 1982fcfd2fbfSGeorge Spelvin goto done; 1983e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1984bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1985bfcfaa77SLinus Torvalds break; 19862a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 1987bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1988bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1989bfcfaa77SLinus Torvalds } 19902a18da7aSGeorge Spelvin x ^= a & bytemask_from_count(len); 1991bfcfaa77SLinus Torvalds done: 19922a18da7aSGeorge Spelvin return fold_hash(x, y); 1993bfcfaa77SLinus Torvalds } 1994bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1995bfcfaa77SLinus Torvalds 1996fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 19978387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 1998fcfd2fbfSGeorge Spelvin { 19998387ff25SLinus Torvalds unsigned long a = 0, x = 0, y = (unsigned long)salt; 20008387ff25SLinus Torvalds unsigned long adata, mask, len; 2001fcfd2fbfSGeorge Spelvin const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2002fcfd2fbfSGeorge Spelvin 20038387ff25SLinus Torvalds len = 0; 20048387ff25SLinus Torvalds goto inside; 20058387ff25SLinus Torvalds 2006fcfd2fbfSGeorge Spelvin do { 20072a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2008fcfd2fbfSGeorge Spelvin len += sizeof(unsigned long); 20098387ff25SLinus Torvalds inside: 2010fcfd2fbfSGeorge Spelvin a = load_unaligned_zeropad(name+len); 2011fcfd2fbfSGeorge Spelvin } while (!has_zero(a, &adata, &constants)); 2012fcfd2fbfSGeorge Spelvin 2013fcfd2fbfSGeorge Spelvin adata = prep_zero_mask(a, adata, &constants); 2014fcfd2fbfSGeorge Spelvin mask = create_zero_mask(adata); 20152a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 2016fcfd2fbfSGeorge Spelvin 20172a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2018fcfd2fbfSGeorge Spelvin } 2019fcfd2fbfSGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2020fcfd2fbfSGeorge Spelvin 2021bfcfaa77SLinus Torvalds /* 2022bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 2023d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 2024bfcfaa77SLinus Torvalds */ 20258387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2026bfcfaa77SLinus Torvalds { 20278387ff25SLinus Torvalds unsigned long a = 0, b, x = 0, y = (unsigned long)salt; 20288387ff25SLinus Torvalds unsigned long adata, bdata, mask, len; 202936126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 2030bfcfaa77SLinus Torvalds 20318387ff25SLinus Torvalds len = 0; 20328387ff25SLinus Torvalds goto inside; 20338387ff25SLinus Torvalds 2034bfcfaa77SLinus Torvalds do { 20352a18da7aSGeorge Spelvin HASH_MIX(x, y, a); 2036bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 20378387ff25SLinus Torvalds inside: 2038e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 203936126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 204036126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 2041bfcfaa77SLinus Torvalds 204236126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 204336126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 204436126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 20452a18da7aSGeorge Spelvin x ^= a & zero_bytemask(mask); 204636126f8fSLinus Torvalds 20472a18da7aSGeorge Spelvin return hashlen_create(fold_hash(x, y), len + find_zero(mask)); 2048bfcfaa77SLinus Torvalds } 2049bfcfaa77SLinus Torvalds 20502a18da7aSGeorge Spelvin #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ 2051bfcfaa77SLinus Torvalds 2052fcfd2fbfSGeorge Spelvin /* Return the hash of a string of known length */ 20538387ff25SLinus Torvalds unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) 20540145acc2SLinus Torvalds { 20558387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 20560145acc2SLinus Torvalds while (len--) 2057fcfd2fbfSGeorge Spelvin hash = partial_name_hash((unsigned char)*name++, hash); 20580145acc2SLinus Torvalds return end_name_hash(hash); 20590145acc2SLinus Torvalds } 2060ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 20610145acc2SLinus Torvalds 2062fcfd2fbfSGeorge Spelvin /* Return the "hash_len" (hash and length) of a null-terminated string */ 20638387ff25SLinus Torvalds u64 hashlen_string(const void *salt, const char *name) 2064fcfd2fbfSGeorge Spelvin { 20658387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2066fcfd2fbfSGeorge Spelvin unsigned long len = 0, c; 2067fcfd2fbfSGeorge Spelvin 2068fcfd2fbfSGeorge Spelvin c = (unsigned char)*name; 2069e0ab7af9SGeorge Spelvin while (c) { 2070fcfd2fbfSGeorge Spelvin len++; 2071fcfd2fbfSGeorge Spelvin hash = partial_name_hash(c, hash); 2072fcfd2fbfSGeorge Spelvin c = (unsigned char)name[len]; 2073e0ab7af9SGeorge Spelvin } 2074fcfd2fbfSGeorge Spelvin return hashlen_create(end_name_hash(hash), len); 2075fcfd2fbfSGeorge Spelvin } 2076f2a031b6SGeorge Spelvin EXPORT_SYMBOL(hashlen_string); 2077fcfd2fbfSGeorge Spelvin 20783ddcd056SLinus Torvalds /* 2079200e9ef7SLinus Torvalds * We know there's a real path component here of at least 2080200e9ef7SLinus Torvalds * one character. 2081200e9ef7SLinus Torvalds */ 20828387ff25SLinus Torvalds static inline u64 hash_name(const void *salt, const char *name) 2083200e9ef7SLinus Torvalds { 20848387ff25SLinus Torvalds unsigned long hash = init_name_hash(salt); 2085200e9ef7SLinus Torvalds unsigned long len = 0, c; 2086200e9ef7SLinus Torvalds 2087200e9ef7SLinus Torvalds c = (unsigned char)*name; 2088200e9ef7SLinus Torvalds do { 2089200e9ef7SLinus Torvalds len++; 2090200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 2091200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 2092200e9ef7SLinus Torvalds } while (c && c != '/'); 2093d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 2094200e9ef7SLinus Torvalds } 2095200e9ef7SLinus Torvalds 2096bfcfaa77SLinus Torvalds #endif 2097bfcfaa77SLinus Torvalds 2098200e9ef7SLinus Torvalds /* 20991da177e4SLinus Torvalds * Name resolution. 2100ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 2101ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 21021da177e4SLinus Torvalds * 2103ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 2104ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 21051da177e4SLinus Torvalds */ 21066de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 21071da177e4SLinus Torvalds { 2108d8d4611aSAl Viro int depth = 0; // depth <= nd->depth 21091da177e4SLinus Torvalds int err; 21101da177e4SLinus Torvalds 2111b4c03536SAl Viro nd->last_type = LAST_ROOT; 2112c108837eSAl Viro nd->flags |= LOOKUP_PARENT; 21139b5858e9SAl Viro if (IS_ERR(name)) 21149b5858e9SAl Viro return PTR_ERR(name); 21151da177e4SLinus Torvalds while (*name=='/') 21161da177e4SLinus Torvalds name++; 21171da177e4SLinus Torvalds if (!*name) 21189e18f10aSAl Viro return 0; 21191da177e4SLinus Torvalds 21201da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 21211da177e4SLinus Torvalds for(;;) { 212292d27016SAl Viro const char *link; 2123d6bb3e90SLinus Torvalds u64 hash_len; 2124fe479a58SAl Viro int type; 21251da177e4SLinus Torvalds 212652094c8aSAl Viro err = may_lookup(nd); 21271da177e4SLinus Torvalds if (err) 21283595e234SAl Viro return err; 21291da177e4SLinus Torvalds 21308387ff25SLinus Torvalds hash_len = hash_name(nd->path.dentry, name); 21311da177e4SLinus Torvalds 2132fe479a58SAl Viro type = LAST_NORM; 2133d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 2134fe479a58SAl Viro case 2: 2135200e9ef7SLinus Torvalds if (name[1] == '.') { 2136fe479a58SAl Viro type = LAST_DOTDOT; 213716c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 213816c2cd71SAl Viro } 2139fe479a58SAl Viro break; 2140fe479a58SAl Viro case 1: 2141fe479a58SAl Viro type = LAST_DOT; 2142fe479a58SAl Viro } 21435a202bcdSAl Viro if (likely(type == LAST_NORM)) { 21445a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 214516c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 21465a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 2147a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 2148da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 21495a202bcdSAl Viro if (err < 0) 21503595e234SAl Viro return err; 2151d6bb3e90SLinus Torvalds hash_len = this.hash_len; 2152d6bb3e90SLinus Torvalds name = this.name; 21535a202bcdSAl Viro } 21545a202bcdSAl Viro } 2155fe479a58SAl Viro 2156d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 2157d6bb3e90SLinus Torvalds nd->last.name = name; 21585f4a6a69SAl Viro nd->last_type = type; 21595f4a6a69SAl Viro 2160d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 2161d6bb3e90SLinus Torvalds if (!*name) 2162bdf6cbf1SAl Viro goto OK; 2163200e9ef7SLinus Torvalds /* 2164200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 2165200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 2166200e9ef7SLinus Torvalds */ 2167200e9ef7SLinus Torvalds do { 2168d6bb3e90SLinus Torvalds name++; 2169d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 21708620c238SAl Viro if (unlikely(!*name)) { 21718620c238SAl Viro OK: 2172d8d4611aSAl Viro /* pathname or trailing symlink, done */ 2173c108837eSAl Viro if (!depth) { 2174c108837eSAl Viro nd->flags &= ~LOOKUP_PARENT; 21758620c238SAl Viro return 0; 2176c108837eSAl Viro } 21778620c238SAl Viro /* last component of nested symlink */ 2178d8d4611aSAl Viro name = nd->stack[--depth].name; 21798c4efe22SAl Viro link = walk_component(nd, 0); 21801c4ff1a8SAl Viro } else { 21811c4ff1a8SAl Viro /* not the last component */ 21828c4efe22SAl Viro link = walk_component(nd, WALK_MORE); 21838620c238SAl Viro } 218492d27016SAl Viro if (unlikely(link)) { 218592d27016SAl Viro if (IS_ERR(link)) 218692d27016SAl Viro return PTR_ERR(link); 218792d27016SAl Viro /* a symlink to follow */ 2188d8d4611aSAl Viro nd->stack[depth++].name = name; 218992d27016SAl Viro name = link; 21909e18f10aSAl Viro continue; 219148c8b0c5SAl Viro } 219297242f99SAl Viro if (unlikely(!d_can_lookup(nd->path.dentry))) { 219397242f99SAl Viro if (nd->flags & LOOKUP_RCU) { 21944675ac39SAl Viro if (unlazy_walk(nd)) 219597242f99SAl Viro return -ECHILD; 219697242f99SAl Viro } 21973595e234SAl Viro return -ENOTDIR; 21985f4a6a69SAl Viro } 2199ce57dfc1SAl Viro } 220097242f99SAl Viro } 22011da177e4SLinus Torvalds 2202edc2b1daSAl Viro /* must be paired with terminate_walk() */ 2203c8a53ee5SAl Viro static const char *path_init(struct nameidata *nd, unsigned flags) 220431e6b01fSNick Piggin { 2205740a1678SAleksa Sarai int error; 2206c8a53ee5SAl Viro const char *s = nd->name->name; 220731e6b01fSNick Piggin 2208c0eb027eSLinus Torvalds if (!*s) 2209c0eb027eSLinus Torvalds flags &= ~LOOKUP_RCU; 2210edc2b1daSAl Viro if (flags & LOOKUP_RCU) 2211edc2b1daSAl Viro rcu_read_lock(); 2212c0eb027eSLinus Torvalds 2213c108837eSAl Viro nd->flags = flags | LOOKUP_JUMPED; 221431e6b01fSNick Piggin nd->depth = 0; 2215ab87f9a5SAleksa Sarai 2216ab87f9a5SAleksa Sarai nd->m_seq = __read_seqcount_begin(&mount_lock.seqcount); 2217ab87f9a5SAleksa Sarai nd->r_seq = __read_seqcount_begin(&rename_lock.seqcount); 2218ab87f9a5SAleksa Sarai smp_rmb(); 2219ab87f9a5SAleksa Sarai 22205b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 2221b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 2222b18825a7SDavid Howells struct inode *inode = root->d_inode; 222393893862SAl Viro if (*s && unlikely(!d_can_lookup(root))) 2224368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 22255b6ca027SAl Viro nd->path = nd->root; 22265b6ca027SAl Viro nd->inode = inode; 22275b6ca027SAl Viro if (flags & LOOKUP_RCU) { 2228ab87f9a5SAleksa Sarai nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22298f47a016SAl Viro nd->root_seq = nd->seq; 22305b6ca027SAl Viro } else { 22315b6ca027SAl Viro path_get(&nd->path); 22325b6ca027SAl Viro } 2233368ee9baSAl Viro return s; 22345b6ca027SAl Viro } 22355b6ca027SAl Viro 223631e6b01fSNick Piggin nd->root.mnt = NULL; 2237248fb5b9SAl Viro nd->path.mnt = NULL; 2238248fb5b9SAl Viro nd->path.dentry = NULL; 223931e6b01fSNick Piggin 22408db52c7eSAleksa Sarai /* Absolute pathname -- fetch the root (LOOKUP_IN_ROOT uses nd->dfd). */ 22418db52c7eSAleksa Sarai if (*s == '/' && !(flags & LOOKUP_IN_ROOT)) { 2242740a1678SAleksa Sarai error = nd_jump_root(nd); 2243740a1678SAleksa Sarai if (unlikely(error)) 2244740a1678SAleksa Sarai return ERR_PTR(error); 2245ef55d917SAl Viro return s; 22468db52c7eSAleksa Sarai } 22478db52c7eSAleksa Sarai 22488db52c7eSAleksa Sarai /* Relative pathname -- get the starting-point it is relative to. */ 22498db52c7eSAleksa Sarai if (nd->dfd == AT_FDCWD) { 2250e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 225131e6b01fSNick Piggin struct fs_struct *fs = current->fs; 2252c28cc364SNick Piggin unsigned seq; 225331e6b01fSNick Piggin 2254c28cc364SNick Piggin do { 2255c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 225631e6b01fSNick Piggin nd->path = fs->pwd; 2257ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2258c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 2259c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 2260e41f7d4eSAl Viro } else { 2261e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 2262ef55d917SAl Viro nd->inode = nd->path.dentry->d_inode; 2263e41f7d4eSAl Viro } 226431e6b01fSNick Piggin } else { 2265582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 2266c8a53ee5SAl Viro struct fd f = fdget_raw(nd->dfd); 226731e6b01fSNick Piggin struct dentry *dentry; 226831e6b01fSNick Piggin 22692903ff01SAl Viro if (!f.file) 2270368ee9baSAl Viro return ERR_PTR(-EBADF); 227131e6b01fSNick Piggin 22722903ff01SAl Viro dentry = f.file->f_path.dentry; 227331e6b01fSNick Piggin 2274edc2b1daSAl Viro if (*s && unlikely(!d_can_lookup(dentry))) { 22752903ff01SAl Viro fdput(f); 2276368ee9baSAl Viro return ERR_PTR(-ENOTDIR); 2277f52e0c11SAl Viro } 22782903ff01SAl Viro 22792903ff01SAl Viro nd->path = f.file->f_path; 2280e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 228134a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 228234a26b99SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 22835590ff0dSUlrich Drepper } else { 22842903ff01SAl Viro path_get(&nd->path); 228534a26b99SAl Viro nd->inode = nd->path.dentry->d_inode; 22861da177e4SLinus Torvalds } 228734a26b99SAl Viro fdput(f); 2288e41f7d4eSAl Viro } 22898db52c7eSAleksa Sarai 2290adb21d2bSAleksa Sarai /* For scoped-lookups we need to set the root to the dirfd as well. */ 2291adb21d2bSAleksa Sarai if (flags & LOOKUP_IS_SCOPED) { 2292adb21d2bSAleksa Sarai nd->root = nd->path; 2293adb21d2bSAleksa Sarai if (flags & LOOKUP_RCU) { 2294adb21d2bSAleksa Sarai nd->root_seq = nd->seq; 2295adb21d2bSAleksa Sarai } else { 2296adb21d2bSAleksa Sarai path_get(&nd->root); 2297adb21d2bSAleksa Sarai nd->flags |= LOOKUP_ROOT_GRABBED; 2298adb21d2bSAleksa Sarai } 2299adb21d2bSAleksa Sarai } 2300adb21d2bSAleksa Sarai return s; 23019b4a9b14SAl Viro } 23029b4a9b14SAl Viro 23031ccac622SAl Viro static inline const char *lookup_last(struct nameidata *nd) 230495fa25d9SAl Viro { 2305bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2306bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2307bd92d7feSAl Viro 2308c108837eSAl Viro return walk_component(nd, WALK_TRAILING); 2309bd92d7feSAl Viro } 2310bd92d7feSAl Viro 23114f757f3cSAl Viro static int handle_lookup_down(struct nameidata *nd) 23124f757f3cSAl Viro { 2313c153007bSAl Viro if (!(nd->flags & LOOKUP_RCU)) 2314db3c9adeSAl Viro dget(nd->path.dentry); 2315b0417d2cSAl Viro return PTR_ERR(step_into(nd, WALK_NOFOLLOW, 2316b0417d2cSAl Viro nd->path.dentry, nd->inode, nd->seq)); 23174f757f3cSAl Viro } 23184f757f3cSAl Viro 23199b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2320c8a53ee5SAl Viro static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) 23219b4a9b14SAl Viro { 2322c8a53ee5SAl Viro const char *s = path_init(nd, flags); 2323bd92d7feSAl Viro int err; 232431e6b01fSNick Piggin 23259b5858e9SAl Viro if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { 23264f757f3cSAl Viro err = handle_lookup_down(nd); 23275f336e72SAl Viro if (unlikely(err < 0)) 23285f336e72SAl Viro s = ERR_PTR(err); 23294f757f3cSAl Viro } 23304f757f3cSAl Viro 23311ccac622SAl Viro while (!(err = link_path_walk(s, nd)) && 23321ccac622SAl Viro (s = lookup_last(nd)) != NULL) 23331ccac622SAl Viro ; 23349f1fafeeSAl Viro if (!err) 23359f1fafeeSAl Viro err = complete_walk(nd); 2336bd92d7feSAl Viro 2337deb106c6SAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) 2338deb106c6SAl Viro if (!d_can_lookup(nd->path.dentry)) 2339bd23a539SAl Viro err = -ENOTDIR; 2340161aff1dSAl Viro if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) { 2341161aff1dSAl Viro err = handle_lookup_down(nd); 2342161aff1dSAl Viro nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please... 2343161aff1dSAl Viro } 2344625b6d10SAl Viro if (!err) { 2345625b6d10SAl Viro *path = nd->path; 2346625b6d10SAl Viro nd->path.mnt = NULL; 2347625b6d10SAl Viro nd->path.dentry = NULL; 2348625b6d10SAl Viro } 2349deb106c6SAl Viro terminate_walk(nd); 2350bd92d7feSAl Viro return err; 235131e6b01fSNick Piggin } 235231e6b01fSNick Piggin 235331d921c7SDavid Howells int filename_lookup(int dfd, struct filename *name, unsigned flags, 23549ad1aaa6SAl Viro struct path *path, struct path *root) 2355873f1eedSJeff Layton { 2356894bc8c4SAl Viro int retval; 23579883d185SAl Viro struct nameidata nd; 2358abc9f5beSAl Viro if (IS_ERR(name)) 2359abc9f5beSAl Viro return PTR_ERR(name); 23609ad1aaa6SAl Viro if (unlikely(root)) { 23619ad1aaa6SAl Viro nd.root = *root; 23629ad1aaa6SAl Viro flags |= LOOKUP_ROOT; 23639ad1aaa6SAl Viro } 23649883d185SAl Viro set_nameidata(&nd, dfd, name); 2365c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); 2366873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 2367c8a53ee5SAl Viro retval = path_lookupat(&nd, flags, path); 2368873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 2369c8a53ee5SAl Viro retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); 2370873f1eedSJeff Layton 2371873f1eedSJeff Layton if (likely(!retval)) 2372161aff1dSAl Viro audit_inode(name, path->dentry, 2373161aff1dSAl Viro flags & LOOKUP_MOUNTPOINT ? AUDIT_INODE_NOEVAL : 0); 23749883d185SAl Viro restore_nameidata(); 2375e4bd1c1aSAl Viro putname(name); 2376873f1eedSJeff Layton return retval; 2377873f1eedSJeff Layton } 2378873f1eedSJeff Layton 23798bcb77faSAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 2380c8a53ee5SAl Viro static int path_parentat(struct nameidata *nd, unsigned flags, 2381391172c4SAl Viro struct path *parent) 23828bcb77faSAl Viro { 2383c8a53ee5SAl Viro const char *s = path_init(nd, flags); 23849b5858e9SAl Viro int err = link_path_walk(s, nd); 23858bcb77faSAl Viro if (!err) 23868bcb77faSAl Viro err = complete_walk(nd); 2387391172c4SAl Viro if (!err) { 2388391172c4SAl Viro *parent = nd->path; 2389391172c4SAl Viro nd->path.mnt = NULL; 2390391172c4SAl Viro nd->path.dentry = NULL; 2391391172c4SAl Viro } 2392deb106c6SAl Viro terminate_walk(nd); 23938bcb77faSAl Viro return err; 23948bcb77faSAl Viro } 23958bcb77faSAl Viro 23965c31b6ceSAl Viro static struct filename *filename_parentat(int dfd, struct filename *name, 2397391172c4SAl Viro unsigned int flags, struct path *parent, 2398391172c4SAl Viro struct qstr *last, int *type) 23998bcb77faSAl Viro { 24008bcb77faSAl Viro int retval; 24019883d185SAl Viro struct nameidata nd; 24028bcb77faSAl Viro 24035c31b6ceSAl Viro if (IS_ERR(name)) 24045c31b6ceSAl Viro return name; 24059883d185SAl Viro set_nameidata(&nd, dfd, name); 2406c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); 24078bcb77faSAl Viro if (unlikely(retval == -ECHILD)) 2408c8a53ee5SAl Viro retval = path_parentat(&nd, flags, parent); 24098bcb77faSAl Viro if (unlikely(retval == -ESTALE)) 2410c8a53ee5SAl Viro retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); 2411391172c4SAl Viro if (likely(!retval)) { 2412391172c4SAl Viro *last = nd.last; 2413391172c4SAl Viro *type = nd.last_type; 2414c9b07eabSAl Viro audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); 24155c31b6ceSAl Viro } else { 24165c31b6ceSAl Viro putname(name); 24175c31b6ceSAl Viro name = ERR_PTR(retval); 2418391172c4SAl Viro } 24199883d185SAl Viro restore_nameidata(); 24205c31b6ceSAl Viro return name; 24218bcb77faSAl Viro } 24228bcb77faSAl Viro 242379714f72SAl Viro /* does lookup, returns the object with parent locked */ 242479714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 24255590ff0dSUlrich Drepper { 24265c31b6ceSAl Viro struct filename *filename; 24275c31b6ceSAl Viro struct dentry *d; 2428391172c4SAl Viro struct qstr last; 2429391172c4SAl Viro int type; 243051689104SPaul Moore 24315c31b6ceSAl Viro filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, 24325c31b6ceSAl Viro &last, &type); 243351689104SPaul Moore if (IS_ERR(filename)) 243451689104SPaul Moore return ERR_CAST(filename); 24355c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) { 2436391172c4SAl Viro path_put(path); 24375c31b6ceSAl Viro putname(filename); 24385c31b6ceSAl Viro return ERR_PTR(-EINVAL); 243979714f72SAl Viro } 24405955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 2441391172c4SAl Viro d = __lookup_hash(&last, path->dentry, 0); 244279714f72SAl Viro if (IS_ERR(d)) { 24435955102cSAl Viro inode_unlock(path->dentry->d_inode); 2444391172c4SAl Viro path_put(path); 244579714f72SAl Viro } 244651689104SPaul Moore putname(filename); 244779714f72SAl Viro return d; 24485590ff0dSUlrich Drepper } 24495590ff0dSUlrich Drepper 2450d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2451d1811465SAl Viro { 2452abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2453abc9f5beSAl Viro flags, path, NULL); 2454d1811465SAl Viro } 24554d359507SAl Viro EXPORT_SYMBOL(kern_path); 2456d1811465SAl Viro 245716f18200SJosef 'Jeff' Sipek /** 245816f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 245916f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 246016f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 246116f18200SJosef 'Jeff' Sipek * @name: pointer to file name 246216f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2463e0a01249SAl Viro * @path: pointer to struct path to fill 246416f18200SJosef 'Jeff' Sipek */ 246516f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 246616f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2467e0a01249SAl Viro struct path *path) 246816f18200SJosef 'Jeff' Sipek { 24699ad1aaa6SAl Viro struct path root = {.mnt = mnt, .dentry = dentry}; 24709ad1aaa6SAl Viro /* the first argument of filename_lookup() is ignored with root */ 2471abc9f5beSAl Viro return filename_lookup(AT_FDCWD, getname_kernel(name), 2472abc9f5beSAl Viro flags , path, &root); 247316f18200SJosef 'Jeff' Sipek } 24744d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 247516f18200SJosef 'Jeff' Sipek 24763c95f0dcSAl Viro static int lookup_one_len_common(const char *name, struct dentry *base, 24773c95f0dcSAl Viro int len, struct qstr *this) 24783c95f0dcSAl Viro { 24793c95f0dcSAl Viro this->name = name; 24803c95f0dcSAl Viro this->len = len; 24813c95f0dcSAl Viro this->hash = full_name_hash(base, name, len); 24823c95f0dcSAl Viro if (!len) 24833c95f0dcSAl Viro return -EACCES; 24843c95f0dcSAl Viro 24853c95f0dcSAl Viro if (unlikely(name[0] == '.')) { 24863c95f0dcSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 24873c95f0dcSAl Viro return -EACCES; 24883c95f0dcSAl Viro } 24893c95f0dcSAl Viro 24903c95f0dcSAl Viro while (len--) { 24913c95f0dcSAl Viro unsigned int c = *(const unsigned char *)name++; 24923c95f0dcSAl Viro if (c == '/' || c == '\0') 24933c95f0dcSAl Viro return -EACCES; 24943c95f0dcSAl Viro } 24953c95f0dcSAl Viro /* 24963c95f0dcSAl Viro * See if the low-level filesystem might want 24973c95f0dcSAl Viro * to use its own hash.. 24983c95f0dcSAl Viro */ 24993c95f0dcSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 25003c95f0dcSAl Viro int err = base->d_op->d_hash(base, this); 25013c95f0dcSAl Viro if (err < 0) 25023c95f0dcSAl Viro return err; 25033c95f0dcSAl Viro } 25043c95f0dcSAl Viro 25053c95f0dcSAl Viro return inode_permission(base->d_inode, MAY_EXEC); 25063c95f0dcSAl Viro } 25073c95f0dcSAl Viro 2508eead1911SChristoph Hellwig /** 25090da0b7fdSDavid Howells * try_lookup_one_len - filesystem helper to lookup single pathname component 25100da0b7fdSDavid Howells * @name: pathname component to lookup 25110da0b7fdSDavid Howells * @base: base directory to lookup from 25120da0b7fdSDavid Howells * @len: maximum length @len should be interpreted to 25130da0b7fdSDavid Howells * 25140da0b7fdSDavid Howells * Look up a dentry by name in the dcache, returning NULL if it does not 25150da0b7fdSDavid Howells * currently exist. The function does not try to create a dentry. 25160da0b7fdSDavid Howells * 25170da0b7fdSDavid Howells * Note that this routine is purely a helper for filesystem usage and should 25180da0b7fdSDavid Howells * not be called by generic code. 25190da0b7fdSDavid Howells * 25200da0b7fdSDavid Howells * The caller must hold base->i_mutex. 25210da0b7fdSDavid Howells */ 25220da0b7fdSDavid Howells struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) 25230da0b7fdSDavid Howells { 25240da0b7fdSDavid Howells struct qstr this; 25250da0b7fdSDavid Howells int err; 25260da0b7fdSDavid Howells 25270da0b7fdSDavid Howells WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25280da0b7fdSDavid Howells 25290da0b7fdSDavid Howells err = lookup_one_len_common(name, base, len, &this); 25300da0b7fdSDavid Howells if (err) 25310da0b7fdSDavid Howells return ERR_PTR(err); 25320da0b7fdSDavid Howells 25330da0b7fdSDavid Howells return lookup_dcache(&this, base, 0); 25340da0b7fdSDavid Howells } 25350da0b7fdSDavid Howells EXPORT_SYMBOL(try_lookup_one_len); 25360da0b7fdSDavid Howells 25370da0b7fdSDavid Howells /** 2538a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2539eead1911SChristoph Hellwig * @name: pathname component to lookup 2540eead1911SChristoph Hellwig * @base: base directory to lookup from 2541eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2542eead1911SChristoph Hellwig * 2543a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 25449e7543e9SAl Viro * not be called by generic code. 2545bbddca8eSNeilBrown * 2546bbddca8eSNeilBrown * The caller must hold base->i_mutex. 2547eead1911SChristoph Hellwig */ 2548057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2549057f6c01SJames Morris { 25508613a209SAl Viro struct dentry *dentry; 2551057f6c01SJames Morris struct qstr this; 2552cda309deSMiklos Szeredi int err; 2553057f6c01SJames Morris 25545955102cSAl Viro WARN_ON_ONCE(!inode_is_locked(base->d_inode)); 25552f9092e1SDavid Woodhouse 25563c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2557cda309deSMiklos Szeredi if (err) 2558cda309deSMiklos Szeredi return ERR_PTR(err); 2559cda309deSMiklos Szeredi 25608613a209SAl Viro dentry = lookup_dcache(&this, base, 0); 25618613a209SAl Viro return dentry ? dentry : __lookup_slow(&this, base, 0); 2562057f6c01SJames Morris } 25634d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2564057f6c01SJames Morris 2565bbddca8eSNeilBrown /** 2566bbddca8eSNeilBrown * lookup_one_len_unlocked - filesystem helper to lookup single pathname component 2567bbddca8eSNeilBrown * @name: pathname component to lookup 2568bbddca8eSNeilBrown * @base: base directory to lookup from 2569bbddca8eSNeilBrown * @len: maximum length @len should be interpreted to 2570bbddca8eSNeilBrown * 2571bbddca8eSNeilBrown * Note that this routine is purely a helper for filesystem usage and should 2572bbddca8eSNeilBrown * not be called by generic code. 2573bbddca8eSNeilBrown * 2574bbddca8eSNeilBrown * Unlike lookup_one_len, it should be called without the parent 2575bbddca8eSNeilBrown * i_mutex held, and will take the i_mutex itself if necessary. 2576bbddca8eSNeilBrown */ 2577bbddca8eSNeilBrown struct dentry *lookup_one_len_unlocked(const char *name, 2578bbddca8eSNeilBrown struct dentry *base, int len) 2579bbddca8eSNeilBrown { 2580bbddca8eSNeilBrown struct qstr this; 2581bbddca8eSNeilBrown int err; 258220d00ee8SLinus Torvalds struct dentry *ret; 2583bbddca8eSNeilBrown 25843c95f0dcSAl Viro err = lookup_one_len_common(name, base, len, &this); 2585bbddca8eSNeilBrown if (err) 2586bbddca8eSNeilBrown return ERR_PTR(err); 2587bbddca8eSNeilBrown 258820d00ee8SLinus Torvalds ret = lookup_dcache(&this, base, 0); 258920d00ee8SLinus Torvalds if (!ret) 259020d00ee8SLinus Torvalds ret = lookup_slow(&this, base, 0); 259120d00ee8SLinus Torvalds return ret; 2592bbddca8eSNeilBrown } 2593bbddca8eSNeilBrown EXPORT_SYMBOL(lookup_one_len_unlocked); 2594bbddca8eSNeilBrown 25956c2d4798SAl Viro /* 25966c2d4798SAl Viro * Like lookup_one_len_unlocked(), except that it yields ERR_PTR(-ENOENT) 25976c2d4798SAl Viro * on negatives. Returns known positive or ERR_PTR(); that's what 25986c2d4798SAl Viro * most of the users want. Note that pinned negative with unlocked parent 25996c2d4798SAl Viro * _can_ become positive at any time, so callers of lookup_one_len_unlocked() 26006c2d4798SAl Viro * need to be very careful; pinned positives have ->d_inode stable, so 26016c2d4798SAl Viro * this one avoids such problems. 26026c2d4798SAl Viro */ 26036c2d4798SAl Viro struct dentry *lookup_positive_unlocked(const char *name, 26046c2d4798SAl Viro struct dentry *base, int len) 26056c2d4798SAl Viro { 26066c2d4798SAl Viro struct dentry *ret = lookup_one_len_unlocked(name, base, len); 26072fa6b1e0SAl Viro if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { 26086c2d4798SAl Viro dput(ret); 26096c2d4798SAl Viro ret = ERR_PTR(-ENOENT); 26106c2d4798SAl Viro } 26116c2d4798SAl Viro return ret; 26126c2d4798SAl Viro } 26136c2d4798SAl Viro EXPORT_SYMBOL(lookup_positive_unlocked); 26146c2d4798SAl Viro 2615eedf265aSEric W. Biederman #ifdef CONFIG_UNIX98_PTYS 2616eedf265aSEric W. Biederman int path_pts(struct path *path) 2617eedf265aSEric W. Biederman { 2618eedf265aSEric W. Biederman /* Find something mounted on "pts" in the same directory as 2619eedf265aSEric W. Biederman * the input path. 2620eedf265aSEric W. Biederman */ 2621a6a7eb76SAl Viro struct dentry *parent = dget_parent(path->dentry); 2622a6a7eb76SAl Viro struct dentry *child; 262319f6028aSAl Viro struct qstr this = QSTR_INIT("pts", 3); 2624eedf265aSEric W. Biederman 2625a6a7eb76SAl Viro if (unlikely(!path_connected(path->mnt, parent))) { 2626a6a7eb76SAl Viro dput(parent); 262763b27720SAl Viro return -ENOENT; 2628a6a7eb76SAl Viro } 262963b27720SAl Viro dput(path->dentry); 263063b27720SAl Viro path->dentry = parent; 2631eedf265aSEric W. Biederman child = d_hash_and_lookup(parent, &this); 2632eedf265aSEric W. Biederman if (!child) 2633eedf265aSEric W. Biederman return -ENOENT; 2634eedf265aSEric W. Biederman 2635eedf265aSEric W. Biederman path->dentry = child; 2636eedf265aSEric W. Biederman dput(parent); 263719f6028aSAl Viro follow_down(path); 2638eedf265aSEric W. Biederman return 0; 2639eedf265aSEric W. Biederman } 2640eedf265aSEric W. Biederman #endif 2641eedf265aSEric W. Biederman 26421fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 26431fa1e7f6SAndy Whitcroft struct path *path, int *empty) 26441da177e4SLinus Torvalds { 2645abc9f5beSAl Viro return filename_lookup(dfd, getname_flags(name, flags, empty), 2646abc9f5beSAl Viro flags, path, NULL); 26471da177e4SLinus Torvalds } 2648b853a161SAl Viro EXPORT_SYMBOL(user_path_at_empty); 26491fa1e7f6SAndy Whitcroft 2650cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 26511da177e4SLinus Torvalds { 26528e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2653da9592edSDavid Howells 26548e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 26551da177e4SLinus Torvalds return 0; 26568e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 26571da177e4SLinus Torvalds return 0; 265823adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 26591da177e4SLinus Torvalds } 2660cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 26611da177e4SLinus Torvalds 26621da177e4SLinus Torvalds /* 26631da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 26641da177e4SLinus Torvalds * whether the type of victim is right. 26651da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 26661da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 26671da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 26681da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 26691da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 26701da177e4SLinus Torvalds * a. be owner of dir, or 26711da177e4SLinus Torvalds * b. be owner of victim, or 26721da177e4SLinus Torvalds * c. have CAP_FOWNER capability 26731da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 26741da177e4SLinus Torvalds * links pointing to it. 26750bd23d09SEric W. Biederman * 7. If the victim has an unknown uid or gid we can't change the inode. 26760bd23d09SEric W. Biederman * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. 26770bd23d09SEric W. Biederman * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. 26780bd23d09SEric W. Biederman * 10. We can't remove a root or mountpoint. 26790bd23d09SEric W. Biederman * 11. We don't allow removal of NFS sillyrenamed files; it's handled by 26801da177e4SLinus Torvalds * nfs_async_unlink(). 26811da177e4SLinus Torvalds */ 2682b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 26831da177e4SLinus Torvalds { 268463afdfc7SDavid Howells struct inode *inode = d_backing_inode(victim); 26851da177e4SLinus Torvalds int error; 26861da177e4SLinus Torvalds 2687b18825a7SDavid Howells if (d_is_negative(victim)) 26881da177e4SLinus Torvalds return -ENOENT; 2689b18825a7SDavid Howells BUG_ON(!inode); 26901da177e4SLinus Torvalds 26911da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 2692593d1ce8SEric W. Biederman 2693593d1ce8SEric W. Biederman /* Inode writeback is not safe when the uid or gid are invalid. */ 2694593d1ce8SEric W. Biederman if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) 2695593d1ce8SEric W. Biederman return -EOVERFLOW; 2696593d1ce8SEric W. Biederman 26974fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 26981da177e4SLinus Torvalds 2699f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 27001da177e4SLinus Torvalds if (error) 27011da177e4SLinus Torvalds return error; 27021da177e4SLinus Torvalds if (IS_APPEND(dir)) 27031da177e4SLinus Torvalds return -EPERM; 2704b18825a7SDavid Howells 2705b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 27060bd23d09SEric W. Biederman IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) 27071da177e4SLinus Torvalds return -EPERM; 27081da177e4SLinus Torvalds if (isdir) { 270944b1d530SMiklos Szeredi if (!d_is_dir(victim)) 27101da177e4SLinus Torvalds return -ENOTDIR; 27111da177e4SLinus Torvalds if (IS_ROOT(victim)) 27121da177e4SLinus Torvalds return -EBUSY; 271344b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 27141da177e4SLinus Torvalds return -EISDIR; 27151da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27161da177e4SLinus Torvalds return -ENOENT; 27171da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 27181da177e4SLinus Torvalds return -EBUSY; 27191da177e4SLinus Torvalds return 0; 27201da177e4SLinus Torvalds } 27211da177e4SLinus Torvalds 27221da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 27231da177e4SLinus Torvalds * dir. 27241da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 27251da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 27261da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 2727036d5236SEric W. Biederman * 3. We can't do it if the fs can't represent the fsuid or fsgid. 2728036d5236SEric W. Biederman * 4. We should have write and exec permissions on dir 2729036d5236SEric W. Biederman * 5. We can't do it if dir is immutable (done in permission()) 27301da177e4SLinus Torvalds */ 2731a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 27321da177e4SLinus Torvalds { 2733036d5236SEric W. Biederman struct user_namespace *s_user_ns; 273414e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 27351da177e4SLinus Torvalds if (child->d_inode) 27361da177e4SLinus Torvalds return -EEXIST; 27371da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 27381da177e4SLinus Torvalds return -ENOENT; 2739036d5236SEric W. Biederman s_user_ns = dir->i_sb->s_user_ns; 2740036d5236SEric W. Biederman if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 2741036d5236SEric W. Biederman !kgid_has_mapping(s_user_ns, current_fsgid())) 2742036d5236SEric W. Biederman return -EOVERFLOW; 2743f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 27441da177e4SLinus Torvalds } 27451da177e4SLinus Torvalds 27461da177e4SLinus Torvalds /* 27471da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 27481da177e4SLinus Torvalds */ 27491da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 27501da177e4SLinus Torvalds { 27511da177e4SLinus Torvalds struct dentry *p; 27521da177e4SLinus Torvalds 27531da177e4SLinus Torvalds if (p1 == p2) { 27545955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27551da177e4SLinus Torvalds return NULL; 27561da177e4SLinus Torvalds } 27571da177e4SLinus Torvalds 2758fc64005cSAl Viro mutex_lock(&p1->d_sb->s_vfs_rename_mutex); 27591da177e4SLinus Torvalds 2760e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2761e2761a11SOGAWA Hirofumi if (p) { 27625955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); 27635955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); 27641da177e4SLinus Torvalds return p; 27651da177e4SLinus Torvalds } 27661da177e4SLinus Torvalds 2767e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2768e2761a11SOGAWA Hirofumi if (p) { 27695955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27705955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); 27711da177e4SLinus Torvalds return p; 27721da177e4SLinus Torvalds } 27731da177e4SLinus Torvalds 27745955102cSAl Viro inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); 27755955102cSAl Viro inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); 27761da177e4SLinus Torvalds return NULL; 27771da177e4SLinus Torvalds } 27784d359507SAl Viro EXPORT_SYMBOL(lock_rename); 27791da177e4SLinus Torvalds 27801da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 27811da177e4SLinus Torvalds { 27825955102cSAl Viro inode_unlock(p1->d_inode); 27831da177e4SLinus Torvalds if (p1 != p2) { 27845955102cSAl Viro inode_unlock(p2->d_inode); 2785fc64005cSAl Viro mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); 27861da177e4SLinus Torvalds } 27871da177e4SLinus Torvalds } 27884d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 27891da177e4SLinus Torvalds 27904acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2791312b63fbSAl Viro bool want_excl) 27921da177e4SLinus Torvalds { 2793a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 27941da177e4SLinus Torvalds if (error) 27951da177e4SLinus Torvalds return error; 27961da177e4SLinus Torvalds 2797acfa4380SAl Viro if (!dir->i_op->create) 27981da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 27991da177e4SLinus Torvalds mode &= S_IALLUGO; 28001da177e4SLinus Torvalds mode |= S_IFREG; 28011da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 28021da177e4SLinus Torvalds if (error) 28031da177e4SLinus Torvalds return error; 2804312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2805a74574aaSStephen Smalley if (!error) 2806f38aa942SAmy Griffis fsnotify_create(dir, dentry); 28071da177e4SLinus Torvalds return error; 28081da177e4SLinus Torvalds } 28094d359507SAl Viro EXPORT_SYMBOL(vfs_create); 28101da177e4SLinus Torvalds 28118e6c848eSAl Viro int vfs_mkobj(struct dentry *dentry, umode_t mode, 28128e6c848eSAl Viro int (*f)(struct dentry *, umode_t, void *), 28138e6c848eSAl Viro void *arg) 28148e6c848eSAl Viro { 28158e6c848eSAl Viro struct inode *dir = dentry->d_parent->d_inode; 28168e6c848eSAl Viro int error = may_create(dir, dentry); 28178e6c848eSAl Viro if (error) 28188e6c848eSAl Viro return error; 28198e6c848eSAl Viro 28208e6c848eSAl Viro mode &= S_IALLUGO; 28218e6c848eSAl Viro mode |= S_IFREG; 28228e6c848eSAl Viro error = security_inode_create(dir, dentry, mode); 28238e6c848eSAl Viro if (error) 28248e6c848eSAl Viro return error; 28258e6c848eSAl Viro error = f(dentry, mode, arg); 28268e6c848eSAl Viro if (!error) 28278e6c848eSAl Viro fsnotify_create(dir, dentry); 28288e6c848eSAl Viro return error; 28298e6c848eSAl Viro } 28308e6c848eSAl Viro EXPORT_SYMBOL(vfs_mkobj); 28318e6c848eSAl Viro 2832a2982cc9SEric W. Biederman bool may_open_dev(const struct path *path) 2833a2982cc9SEric W. Biederman { 2834a2982cc9SEric W. Biederman return !(path->mnt->mnt_flags & MNT_NODEV) && 2835a2982cc9SEric W. Biederman !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); 2836a2982cc9SEric W. Biederman } 2837a2982cc9SEric W. Biederman 2838f0bb5aafSAl Viro static int may_open(const struct path *path, int acc_mode, int flag) 28391da177e4SLinus Torvalds { 28403fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 28411da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 28421da177e4SLinus Torvalds int error; 28431da177e4SLinus Torvalds 28441da177e4SLinus Torvalds if (!inode) 28451da177e4SLinus Torvalds return -ENOENT; 28461da177e4SLinus Torvalds 2847c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2848c8fe8f30SChristoph Hellwig case S_IFLNK: 28491da177e4SLinus Torvalds return -ELOOP; 2850c8fe8f30SChristoph Hellwig case S_IFDIR: 2851c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 28521da177e4SLinus Torvalds return -EISDIR; 2853c8fe8f30SChristoph Hellwig break; 2854c8fe8f30SChristoph Hellwig case S_IFBLK: 2855c8fe8f30SChristoph Hellwig case S_IFCHR: 2856a2982cc9SEric W. Biederman if (!may_open_dev(path)) 28571da177e4SLinus Torvalds return -EACCES; 2858c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2859c8fe8f30SChristoph Hellwig case S_IFIFO: 2860c8fe8f30SChristoph Hellwig case S_IFSOCK: 28611da177e4SLinus Torvalds flag &= ~O_TRUNC; 2862c8fe8f30SChristoph Hellwig break; 28634a3fd211SDave Hansen } 2864b41572e9SDave Hansen 286562fb4a15SAl Viro error = inode_permission(inode, MAY_OPEN | acc_mode); 2866b41572e9SDave Hansen if (error) 2867b41572e9SDave Hansen return error; 28686146f0d5SMimi Zohar 28691da177e4SLinus Torvalds /* 28701da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 28711da177e4SLinus Torvalds */ 28721da177e4SLinus Torvalds if (IS_APPEND(inode)) { 28738737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 28747715b521SAl Viro return -EPERM; 28751da177e4SLinus Torvalds if (flag & O_TRUNC) 28767715b521SAl Viro return -EPERM; 28771da177e4SLinus Torvalds } 28781da177e4SLinus Torvalds 28791da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 28802e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 28817715b521SAl Viro return -EPERM; 28821da177e4SLinus Torvalds 2883f3c7691eSJ. Bruce Fields return 0; 28847715b521SAl Viro } 28857715b521SAl Viro 2886e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 28877715b521SAl Viro { 2888f0bb5aafSAl Viro const struct path *path = &filp->f_path; 28897715b521SAl Viro struct inode *inode = path->dentry->d_inode; 28907715b521SAl Viro int error = get_write_access(inode); 28911da177e4SLinus Torvalds if (error) 28927715b521SAl Viro return error; 28931da177e4SLinus Torvalds /* 28941da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 28951da177e4SLinus Torvalds */ 2896d7a06983SJeff Layton error = locks_verify_locked(filp); 2897be6d3e56SKentaro Takeda if (!error) 2898ea0d3ab2STetsuo Handa error = security_path_truncate(path); 28991da177e4SLinus Torvalds if (!error) { 29007715b521SAl Viro error = do_truncate(path->dentry, 0, 2901d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2902e1181ee6SJeff Layton filp); 29031da177e4SLinus Torvalds } 29041da177e4SLinus Torvalds put_write_access(inode); 2905acd0c935SMimi Zohar return error; 29061da177e4SLinus Torvalds } 29071da177e4SLinus Torvalds 2908d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2909d57999e1SDave Hansen { 29108a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 29118a5e929dSAl Viro flag--; 2912d57999e1SDave Hansen return flag; 2913d57999e1SDave Hansen } 2914d57999e1SDave Hansen 2915d3607752SAl Viro static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) 2916d18e9008SMiklos Szeredi { 29171328c727SSeth Forshee struct user_namespace *s_user_ns; 2918d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2919d18e9008SMiklos Szeredi if (error) 2920d18e9008SMiklos Szeredi return error; 2921d18e9008SMiklos Szeredi 29221328c727SSeth Forshee s_user_ns = dir->dentry->d_sb->s_user_ns; 29231328c727SSeth Forshee if (!kuid_has_mapping(s_user_ns, current_fsuid()) || 29241328c727SSeth Forshee !kgid_has_mapping(s_user_ns, current_fsgid())) 29251328c727SSeth Forshee return -EOVERFLOW; 29261328c727SSeth Forshee 2927d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2928d18e9008SMiklos Szeredi if (error) 2929d18e9008SMiklos Szeredi return error; 2930d18e9008SMiklos Szeredi 2931d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2932d18e9008SMiklos Szeredi } 2933d18e9008SMiklos Szeredi 29341acf0af9SDavid Howells /* 29351acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 29361acf0af9SDavid Howells * dentry. 29371acf0af9SDavid Howells * 29381acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 29391acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 29401acf0af9SDavid Howells * 294100a07c15SAl Viro * If the file was looked up only or didn't need creating, FMODE_OPENED won't 294200a07c15SAl Viro * be set. The caller will need to perform the open themselves. @path will 294300a07c15SAl Viro * have been updated to point to the new dentry. This may be negative. 29441acf0af9SDavid Howells * 29451acf0af9SDavid Howells * Returns an error code otherwise. 29461acf0af9SDavid Howells */ 2947239eb983SAl Viro static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry, 2948239eb983SAl Viro struct file *file, 2949015c3bbcSMiklos Szeredi const struct open_flags *op, 29503ec2eef1SAl Viro int open_flag, umode_t mode) 2951d18e9008SMiklos Szeredi { 2952d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2953d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2954d18e9008SMiklos Szeredi int error; 2955d18e9008SMiklos Szeredi 2956384f26e2SAl Viro if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ 2957d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2958d18e9008SMiklos Szeredi 2959d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2960d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2961d18e9008SMiklos Szeredi 296230d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 296330d90494SAl Viro file->f_path.mnt = nd->path.mnt; 29640fb1ea09SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, 296544907d79SAl Viro open_to_namei_flags(open_flag), mode); 29666fbd0714SAl Viro d_lookup_done(dentry); 2967384f26e2SAl Viro if (!error) { 296864e1ac4dSAl Viro if (file->f_mode & FMODE_OPENED) { 29696fb968cdSAl Viro if (unlikely(dentry != file->f_path.dentry)) { 29706fb968cdSAl Viro dput(dentry); 29716fb968cdSAl Viro dentry = dget(file->f_path.dentry); 29726fb968cdSAl Viro } 29737be219b4SAl Viro if (file->f_mode & FMODE_CREATED) 297403da633aSAl Viro fsnotify_create(dir, dentry); 297564e1ac4dSAl Viro } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 2976116cc022SMiklos Szeredi error = -EIO; 2977384f26e2SAl Viro } else { 2978d18e9008SMiklos Szeredi if (file->f_path.dentry) { 2979d18e9008SMiklos Szeredi dput(dentry); 2980d18e9008SMiklos Szeredi dentry = file->f_path.dentry; 298110c64ceaSAl Viro } 298273a09dd9SAl Viro if (file->f_mode & FMODE_CREATED) 2983d18e9008SMiklos Szeredi fsnotify_create(dir, dentry); 2984239eb983SAl Viro if (unlikely(d_is_negative(dentry))) 2985a01e718fSAl Viro error = -ENOENT; 2986d18e9008SMiklos Szeredi } 2987d18e9008SMiklos Szeredi } 2988239eb983SAl Viro if (error) { 2989d18e9008SMiklos Szeredi dput(dentry); 2990239eb983SAl Viro dentry = ERR_PTR(error); 2991239eb983SAl Viro } 2992239eb983SAl Viro return dentry; 2993d18e9008SMiklos Szeredi } 2994d18e9008SMiklos Szeredi 299531e6b01fSNick Piggin /* 29961acf0af9SDavid Howells * Look up and maybe create and open the last component. 2997d58ffd35SMiklos Szeredi * 299800a07c15SAl Viro * Must be called with parent locked (exclusive in O_CREAT case). 2999d58ffd35SMiklos Szeredi * 300000a07c15SAl Viro * Returns 0 on success, that is, if 300100a07c15SAl Viro * the file was successfully atomically created (if necessary) and opened, or 300200a07c15SAl Viro * the file was not completely opened at this time, though lookups and 300300a07c15SAl Viro * creations were performed. 300400a07c15SAl Viro * These case are distinguished by presence of FMODE_OPENED on file->f_mode. 300500a07c15SAl Viro * In the latter case dentry returned in @path might be negative if O_CREAT 300600a07c15SAl Viro * hadn't been specified. 30071acf0af9SDavid Howells * 300800a07c15SAl Viro * An error code is returned on failure. 3009d58ffd35SMiklos Szeredi */ 3010da5ebf5aSAl Viro static struct dentry *lookup_open(struct nameidata *nd, struct file *file, 3011d58ffd35SMiklos Szeredi const struct open_flags *op, 30123ec2eef1SAl Viro bool got_write) 3013d58ffd35SMiklos Szeredi { 3014d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 301554ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 30161643b43fSAl Viro int open_flag = op->open_flag; 3017d58ffd35SMiklos Szeredi struct dentry *dentry; 30181643b43fSAl Viro int error, create_error = 0; 30191643b43fSAl Viro umode_t mode = op->mode; 30206fbd0714SAl Viro DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); 3021d58ffd35SMiklos Szeredi 3022ce8644fcSAl Viro if (unlikely(IS_DEADDIR(dir_inode))) 3023da5ebf5aSAl Viro return ERR_PTR(-ENOENT); 3024d58ffd35SMiklos Szeredi 302573a09dd9SAl Viro file->f_mode &= ~FMODE_CREATED; 30266fbd0714SAl Viro dentry = d_lookup(dir, &nd->last); 30276fbd0714SAl Viro for (;;) { 30286fbd0714SAl Viro if (!dentry) { 30296fbd0714SAl Viro dentry = d_alloc_parallel(dir, &nd->last, &wq); 3030d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 3031da5ebf5aSAl Viro return dentry; 30326fbd0714SAl Viro } 30336fbd0714SAl Viro if (d_in_lookup(dentry)) 30346fbd0714SAl Viro break; 3035d58ffd35SMiklos Szeredi 30366fbd0714SAl Viro error = d_revalidate(dentry, nd->flags); 30376fbd0714SAl Viro if (likely(error > 0)) 30386fbd0714SAl Viro break; 30396fbd0714SAl Viro if (error) 30406fbd0714SAl Viro goto out_dput; 30416fbd0714SAl Viro d_invalidate(dentry); 30426fbd0714SAl Viro dput(dentry); 30436fbd0714SAl Viro dentry = NULL; 30446fbd0714SAl Viro } 30456fbd0714SAl Viro if (dentry->d_inode) { 3046d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 3047da5ebf5aSAl Viro return dentry; 30486c51e513SAl Viro } 3049d18e9008SMiklos Szeredi 30501643b43fSAl Viro /* 30511643b43fSAl Viro * Checking write permission is tricky, bacuse we don't know if we are 30521643b43fSAl Viro * going to actually need it: O_CREAT opens should work as long as the 30531643b43fSAl Viro * file exists. But checking existence breaks atomicity. The trick is 30541643b43fSAl Viro * to check access and if not granted clear O_CREAT from the flags. 30551643b43fSAl Viro * 30561643b43fSAl Viro * Another problem is returing the "right" error value (e.g. for an 30571643b43fSAl Viro * O_EXCL open we want to return EEXIST not EROFS). 30581643b43fSAl Viro */ 30591643b43fSAl Viro if (open_flag & O_CREAT) { 30601643b43fSAl Viro if (!IS_POSIXACL(dir->d_inode)) 30611643b43fSAl Viro mode &= ~current_umask(); 30621643b43fSAl Viro if (unlikely(!got_write)) { 30631643b43fSAl Viro create_error = -EROFS; 30641643b43fSAl Viro open_flag &= ~O_CREAT; 30651643b43fSAl Viro if (open_flag & (O_EXCL | O_TRUNC)) 30661643b43fSAl Viro goto no_open; 30671643b43fSAl Viro /* No side effects, safe to clear O_CREAT */ 30681643b43fSAl Viro } else { 30691643b43fSAl Viro create_error = may_o_create(&nd->path, dentry, mode); 30701643b43fSAl Viro if (create_error) { 30711643b43fSAl Viro open_flag &= ~O_CREAT; 30721643b43fSAl Viro if (open_flag & O_EXCL) 30731643b43fSAl Viro goto no_open; 30741643b43fSAl Viro } 30751643b43fSAl Viro } 30761643b43fSAl Viro } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && 30771643b43fSAl Viro unlikely(!got_write)) { 30781643b43fSAl Viro /* 30791643b43fSAl Viro * No O_CREATE -> atomicity not a requirement -> fall 30801643b43fSAl Viro * back to lookup + open 30811643b43fSAl Viro */ 30821643b43fSAl Viro goto no_open; 3083d18e9008SMiklos Szeredi } 3084d18e9008SMiklos Szeredi 30851643b43fSAl Viro if (dir_inode->i_op->atomic_open) { 3086239eb983SAl Viro dentry = atomic_open(nd, dentry, file, op, open_flag, mode); 3087da5ebf5aSAl Viro if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT)) 3088da5ebf5aSAl Viro dentry = ERR_PTR(create_error); 3089da5ebf5aSAl Viro return dentry; 3090239eb983SAl Viro } 309154ef4872SMiklos Szeredi 30921643b43fSAl Viro no_open: 30936fbd0714SAl Viro if (d_in_lookup(dentry)) { 309412fa5e24SAl Viro struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, 309512fa5e24SAl Viro nd->flags); 30966fbd0714SAl Viro d_lookup_done(dentry); 309712fa5e24SAl Viro if (unlikely(res)) { 309812fa5e24SAl Viro if (IS_ERR(res)) { 309912fa5e24SAl Viro error = PTR_ERR(res); 310012fa5e24SAl Viro goto out_dput; 310112fa5e24SAl Viro } 310212fa5e24SAl Viro dput(dentry); 310312fa5e24SAl Viro dentry = res; 310412fa5e24SAl Viro } 310554ef4872SMiklos Szeredi } 310654ef4872SMiklos Szeredi 3107d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 31081643b43fSAl Viro if (!dentry->d_inode && (open_flag & O_CREAT)) { 310973a09dd9SAl Viro file->f_mode |= FMODE_CREATED; 3110ce8644fcSAl Viro audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); 3111ce8644fcSAl Viro if (!dir_inode->i_op->create) { 3112ce8644fcSAl Viro error = -EACCES; 3113d58ffd35SMiklos Szeredi goto out_dput; 311464894cf8SAl Viro } 3115ce8644fcSAl Viro error = dir_inode->i_op->create(dir_inode, dentry, mode, 31161643b43fSAl Viro open_flag & O_EXCL); 3117d58ffd35SMiklos Szeredi if (error) 3118d58ffd35SMiklos Szeredi goto out_dput; 3119ce8644fcSAl Viro fsnotify_create(dir_inode, dentry); 3120d58ffd35SMiklos Szeredi } 31211643b43fSAl Viro if (unlikely(create_error) && !dentry->d_inode) { 31221643b43fSAl Viro error = create_error; 3123d58ffd35SMiklos Szeredi goto out_dput; 3124d58ffd35SMiklos Szeredi } 3125da5ebf5aSAl Viro return dentry; 3126d58ffd35SMiklos Szeredi 3127d58ffd35SMiklos Szeredi out_dput: 3128d58ffd35SMiklos Szeredi dput(dentry); 3129da5ebf5aSAl Viro return ERR_PTR(error); 3130d58ffd35SMiklos Szeredi } 3131d58ffd35SMiklos Szeredi 3132c981a482SAl Viro static const char *open_last_lookups(struct nameidata *nd, 31333ec2eef1SAl Viro struct file *file, const struct open_flags *op) 3134fb1cc555SAl Viro { 3135a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 3136ca344a89SAl Viro int open_flag = op->open_flag; 313764894cf8SAl Viro bool got_write = false; 3138254cf582SAl Viro unsigned seq; 3139a1eb3315SMiklos Szeredi struct inode *inode; 3140da5ebf5aSAl Viro struct dentry *dentry; 3141b0417d2cSAl Viro const char *res; 314216c2cd71SAl Viro int error; 3143fb1cc555SAl Viro 3144c3e380b0SAl Viro nd->flags |= op->intent; 3145c3e380b0SAl Viro 3146bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 314756676ec3SAl Viro if (nd->depth) 314856676ec3SAl Viro put_link(nd); 31497521f22bSAl Viro res = handle_dots(nd, nd->last_type); 31507521f22bSAl Viro if (likely(!res)) 31517521f22bSAl Viro res = ERR_PTR(complete_walk(nd)); 31527521f22bSAl Viro return res; 31531f36f774SAl Viro } 3154a2c36b45SAl Viro 3155ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 3156fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 3157fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 3158fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 315920e34357SAl Viro dentry = lookup_fast(nd, &inode, &seq); 316020e34357SAl Viro if (IS_ERR(dentry)) 31611ccac622SAl Viro return ERR_CAST(dentry); 316220e34357SAl Viro if (likely(dentry)) 316371574865SMiklos Szeredi goto finish_lookup; 316471574865SMiklos Szeredi 31656583fe22SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 3166b6183df7SMiklos Szeredi } else { 3167fe2d35ffSAl Viro /* create side of things */ 3168a3fbbde7SAl Viro /* 3169b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 3170b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 3171b6183df7SMiklos Szeredi * about to look up 3172a3fbbde7SAl Viro */ 31739f1fafeeSAl Viro error = complete_walk(nd); 3174c981a482SAl Viro if (unlikely(error)) 31751ccac622SAl Viro return ERR_PTR(error); 3176fe2d35ffSAl Viro 3177c9b07eabSAl Viro audit_inode(nd->name, dir, AUDIT_INODE_PARENT); 31781f36f774SAl Viro /* trailing slashes? */ 3179deb106c6SAl Viro if (unlikely(nd->last.name[nd->last.len])) 31801ccac622SAl Viro return ERR_PTR(-EISDIR); 3181b6183df7SMiklos Szeredi } 31821f36f774SAl Viro 31839cf843e3SAl Viro if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 318464894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 318564894cf8SAl Viro if (!error) 318664894cf8SAl Viro got_write = true; 318764894cf8SAl Viro /* 318864894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 318964894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 319064894cf8SAl Viro * dropping this one anyway. 319164894cf8SAl Viro */ 319264894cf8SAl Viro } 31939cf843e3SAl Viro if (open_flag & O_CREAT) 31945955102cSAl Viro inode_lock(dir->d_inode); 31959cf843e3SAl Viro else 31969cf843e3SAl Viro inode_lock_shared(dir->d_inode); 3197da5ebf5aSAl Viro dentry = lookup_open(nd, file, op, got_write); 31989cf843e3SAl Viro if (open_flag & O_CREAT) 31995955102cSAl Viro inode_unlock(dir->d_inode); 32009cf843e3SAl Viro else 32019cf843e3SAl Viro inode_unlock_shared(dir->d_inode); 3202fb1cc555SAl Viro 3203c981a482SAl Viro if (got_write) 320459e96e65SAl Viro mnt_drop_write(nd->path.mnt); 32056c0d46c4SAl Viro 320659e96e65SAl Viro if (IS_ERR(dentry)) 320759e96e65SAl Viro return ERR_CAST(dentry); 320859e96e65SAl Viro 3209973d4b73SAl Viro if (file->f_mode & (FMODE_OPENED | FMODE_CREATED)) { 3210e73cabffSAl Viro dput(nd->path.dentry); 3211e73cabffSAl Viro nd->path.dentry = dentry; 3212c981a482SAl Viro return NULL; 3213fb1cc555SAl Viro } 3214fb1cc555SAl Viro 321520e34357SAl Viro finish_lookup: 321656676ec3SAl Viro if (nd->depth) 321756676ec3SAl Viro put_link(nd); 32188c4efe22SAl Viro res = step_into(nd, WALK_TRAILING, dentry, inode, seq); 3219b0417d2cSAl Viro if (unlikely(res)) { 32201ccac622SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 3221b0417d2cSAl Viro return res; 32221ccac622SAl Viro } 322331d1726dSAl Viro 322431d1726dSAl Viro if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { 322531d1726dSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 32261ccac622SAl Viro return ERR_PTR(-EEXIST); 322731d1726dSAl Viro } 3228c981a482SAl Viro 32298f64fb1cSAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3230c981a482SAl Viro return ERR_PTR(complete_walk(nd)); 3231c981a482SAl Viro } 3232c981a482SAl Viro 3233c981a482SAl Viro /* 3234c981a482SAl Viro * Handle the last step of open() 3235c981a482SAl Viro */ 3236c981a482SAl Viro static const char *do_last(struct nameidata *nd, 3237c981a482SAl Viro struct file *file, const struct open_flags *op) 3238c981a482SAl Viro { 3239c981a482SAl Viro kuid_t dir_uid = nd->inode->i_uid; 3240c981a482SAl Viro umode_t dir_mode = nd->inode->i_mode; 3241c981a482SAl Viro int open_flag = op->open_flag; 3242c981a482SAl Viro bool do_truncate; 3243c981a482SAl Viro int acc_mode; 3244c981a482SAl Viro const char *link; 3245c981a482SAl Viro int error; 3246c981a482SAl Viro 3247c981a482SAl Viro link = open_last_lookups(nd, file, op); 3248c981a482SAl Viro if (unlikely(link)) 3249c981a482SAl Viro return link; 3250c981a482SAl Viro 3251973d4b73SAl Viro if (!(file->f_mode & FMODE_CREATED)) 325276ae2a5aSAl Viro audit_inode(nd->name, nd->path.dentry, 0); 325330aba665SSalvatore Mesoraca if (open_flag & O_CREAT) { 325430aba665SSalvatore Mesoraca if (d_is_dir(nd->path.dentry)) 325559e96e65SAl Viro return ERR_PTR(-EISDIR); 3256d0cb5018SAl Viro error = may_create_in_sticky(dir_mode, dir_uid, 325730aba665SSalvatore Mesoraca d_backing_inode(nd->path.dentry)); 325830aba665SSalvatore Mesoraca if (unlikely(error)) 325959e96e65SAl Viro return ERR_PTR(error); 326030aba665SSalvatore Mesoraca } 326144b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 326259e96e65SAl Viro return ERR_PTR(-ENOTDIR); 32636c0d46c4SAl Viro 32648795e7d4SAl Viro do_truncate = false; 32658795e7d4SAl Viro acc_mode = op->acc_mode; 32665a2d3eddSAl Viro if (file->f_mode & FMODE_CREATED) { 32675a2d3eddSAl Viro /* Don't check for write permission, don't truncate */ 32685a2d3eddSAl Viro open_flag &= ~O_TRUNC; 32695a2d3eddSAl Viro acc_mode = 0; 32708795e7d4SAl Viro } else if (d_is_reg(nd->path.dentry) && open_flag & O_TRUNC) { 32710f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 32720f9d1a10SAl Viro if (error) 327359e96e65SAl Viro return ERR_PTR(error); 32748795e7d4SAl Viro do_truncate = true; 32750f9d1a10SAl Viro } 3276bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 32778795e7d4SAl Viro if (!error && !(file->f_mode & FMODE_OPENED)) 3278ae2bb293SAl Viro error = vfs_open(&nd->path, file); 32798795e7d4SAl Viro if (!error) 32806035a27bSAl Viro error = ima_file_check(file, op->acc_mode); 32818795e7d4SAl Viro if (!error && do_truncate) 32822675a4ebSAl Viro error = handle_truncate(file); 3283c80567c8SAl Viro if (unlikely(error > 0)) { 3284c80567c8SAl Viro WARN_ON(1); 3285c80567c8SAl Viro error = -EINVAL; 3286c80567c8SAl Viro } 32878795e7d4SAl Viro if (do_truncate) 32880f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 32891ccac622SAl Viro return ERR_PTR(error); 3290fb1cc555SAl Viro } 3291fb1cc555SAl Viro 3292af7bd4dcSAmir Goldstein struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) 3293af7bd4dcSAmir Goldstein { 3294af7bd4dcSAmir Goldstein struct dentry *child = NULL; 3295af7bd4dcSAmir Goldstein struct inode *dir = dentry->d_inode; 3296af7bd4dcSAmir Goldstein struct inode *inode; 3297af7bd4dcSAmir Goldstein int error; 3298af7bd4dcSAmir Goldstein 3299af7bd4dcSAmir Goldstein /* we want directory to be writable */ 3300af7bd4dcSAmir Goldstein error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 3301af7bd4dcSAmir Goldstein if (error) 3302af7bd4dcSAmir Goldstein goto out_err; 3303af7bd4dcSAmir Goldstein error = -EOPNOTSUPP; 3304af7bd4dcSAmir Goldstein if (!dir->i_op->tmpfile) 3305af7bd4dcSAmir Goldstein goto out_err; 3306af7bd4dcSAmir Goldstein error = -ENOMEM; 3307cdf01226SDavid Howells child = d_alloc(dentry, &slash_name); 3308af7bd4dcSAmir Goldstein if (unlikely(!child)) 3309af7bd4dcSAmir Goldstein goto out_err; 3310af7bd4dcSAmir Goldstein error = dir->i_op->tmpfile(dir, child, mode); 3311af7bd4dcSAmir Goldstein if (error) 3312af7bd4dcSAmir Goldstein goto out_err; 3313af7bd4dcSAmir Goldstein error = -ENOENT; 3314af7bd4dcSAmir Goldstein inode = child->d_inode; 3315af7bd4dcSAmir Goldstein if (unlikely(!inode)) 3316af7bd4dcSAmir Goldstein goto out_err; 3317af7bd4dcSAmir Goldstein if (!(open_flag & O_EXCL)) { 3318af7bd4dcSAmir Goldstein spin_lock(&inode->i_lock); 3319af7bd4dcSAmir Goldstein inode->i_state |= I_LINKABLE; 3320af7bd4dcSAmir Goldstein spin_unlock(&inode->i_lock); 3321af7bd4dcSAmir Goldstein } 3322fdb2410fSMimi Zohar ima_post_create_tmpfile(inode); 3323af7bd4dcSAmir Goldstein return child; 3324af7bd4dcSAmir Goldstein 3325af7bd4dcSAmir Goldstein out_err: 3326af7bd4dcSAmir Goldstein dput(child); 3327af7bd4dcSAmir Goldstein return ERR_PTR(error); 3328af7bd4dcSAmir Goldstein } 3329af7bd4dcSAmir Goldstein EXPORT_SYMBOL(vfs_tmpfile); 3330af7bd4dcSAmir Goldstein 3331c8a53ee5SAl Viro static int do_tmpfile(struct nameidata *nd, unsigned flags, 333260545d0dSAl Viro const struct open_flags *op, 33333ec2eef1SAl Viro struct file *file) 333460545d0dSAl Viro { 3335625b6d10SAl Viro struct dentry *child; 3336625b6d10SAl Viro struct path path; 3337c8a53ee5SAl Viro int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); 333860545d0dSAl Viro if (unlikely(error)) 333960545d0dSAl Viro return error; 3340625b6d10SAl Viro error = mnt_want_write(path.mnt); 334160545d0dSAl Viro if (unlikely(error)) 334260545d0dSAl Viro goto out; 3343af7bd4dcSAmir Goldstein child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); 3344af7bd4dcSAmir Goldstein error = PTR_ERR(child); 3345684e73beSHirofumi Nakagawa if (IS_ERR(child)) 334660545d0dSAl Viro goto out2; 3347625b6d10SAl Viro dput(path.dentry); 3348625b6d10SAl Viro path.dentry = child; 3349c8a53ee5SAl Viro audit_inode(nd->name, child, 0); 335069a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 335162fb4a15SAl Viro error = may_open(&path, 0, op->open_flag); 335260545d0dSAl Viro if (error) 335360545d0dSAl Viro goto out2; 3354625b6d10SAl Viro file->f_path.mnt = path.mnt; 3355be12af3eSAl Viro error = finish_open(file, child, NULL); 335660545d0dSAl Viro out2: 3357625b6d10SAl Viro mnt_drop_write(path.mnt); 335860545d0dSAl Viro out: 3359625b6d10SAl Viro path_put(&path); 336060545d0dSAl Viro return error; 336160545d0dSAl Viro } 336260545d0dSAl Viro 33636ac08709SAl Viro static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) 33646ac08709SAl Viro { 33656ac08709SAl Viro struct path path; 33666ac08709SAl Viro int error = path_lookupat(nd, flags, &path); 33676ac08709SAl Viro if (!error) { 33686ac08709SAl Viro audit_inode(nd->name, path.dentry, 0); 3369ae2bb293SAl Viro error = vfs_open(&path, file); 33706ac08709SAl Viro path_put(&path); 33716ac08709SAl Viro } 33726ac08709SAl Viro return error; 33736ac08709SAl Viro } 33746ac08709SAl Viro 3375c8a53ee5SAl Viro static struct file *path_openat(struct nameidata *nd, 3376c8a53ee5SAl Viro const struct open_flags *op, unsigned flags) 33771da177e4SLinus Torvalds { 337830d90494SAl Viro struct file *file; 337913aab428SAl Viro int error; 338031e6b01fSNick Piggin 3381ea73ea72SAl Viro file = alloc_empty_file(op->open_flag, current_cred()); 33821afc99beSAl Viro if (IS_ERR(file)) 33831afc99beSAl Viro return file; 338431e6b01fSNick Piggin 3385bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 33863ec2eef1SAl Viro error = do_tmpfile(nd, flags, op, file); 33875f336e72SAl Viro } else if (unlikely(file->f_flags & O_PATH)) { 33886ac08709SAl Viro error = do_o_path(nd, flags, file); 33895f336e72SAl Viro } else { 33905f336e72SAl Viro const char *s = path_init(nd, flags); 33913bdba28bSAl Viro while (!(error = link_path_walk(s, nd)) && 33921ccac622SAl Viro (s = do_last(nd, file, op)) != NULL) 33931ccac622SAl Viro ; 3394deb106c6SAl Viro terminate_walk(nd); 33955f336e72SAl Viro } 33967c1c01ecSAl Viro if (likely(!error)) { 3397aad888f8SAl Viro if (likely(file->f_mode & FMODE_OPENED)) 33987c1c01ecSAl Viro return file; 33997c1c01ecSAl Viro WARN_ON(1); 34007c1c01ecSAl Viro error = -EINVAL; 3401015c3bbcSMiklos Szeredi } 34027c1c01ecSAl Viro fput(file); 34032675a4ebSAl Viro if (error == -EOPENSTALE) { 34042675a4ebSAl Viro if (flags & LOOKUP_RCU) 34052675a4ebSAl Viro error = -ECHILD; 34062675a4ebSAl Viro else 34072675a4ebSAl Viro error = -ESTALE; 34082675a4ebSAl Viro } 34097c1c01ecSAl Viro return ERR_PTR(error); 3410de459215SKirill Korotaev } 34111da177e4SLinus Torvalds 3412669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3413f9652e10SAl Viro const struct open_flags *op) 341413aab428SAl Viro { 34159883d185SAl Viro struct nameidata nd; 3416f9652e10SAl Viro int flags = op->lookup_flags; 341713aab428SAl Viro struct file *filp; 341813aab428SAl Viro 34199883d185SAl Viro set_nameidata(&nd, dfd, pathname); 3420c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_RCU); 342113aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 3422c8a53ee5SAl Viro filp = path_openat(&nd, op, flags); 342313aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 3424c8a53ee5SAl Viro filp = path_openat(&nd, op, flags | LOOKUP_REVAL); 34259883d185SAl Viro restore_nameidata(); 342613aab428SAl Viro return filp; 342713aab428SAl Viro } 342813aab428SAl Viro 342973d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3430f9652e10SAl Viro const char *name, const struct open_flags *op) 343173d049a4SAl Viro { 34329883d185SAl Viro struct nameidata nd; 343373d049a4SAl Viro struct file *file; 343451689104SPaul Moore struct filename *filename; 3435f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 343673d049a4SAl Viro 343773d049a4SAl Viro nd.root.mnt = mnt; 343873d049a4SAl Viro nd.root.dentry = dentry; 343973d049a4SAl Viro 3440b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 344173d049a4SAl Viro return ERR_PTR(-ELOOP); 344273d049a4SAl Viro 344351689104SPaul Moore filename = getname_kernel(name); 3444a1c83681SViresh Kumar if (IS_ERR(filename)) 344551689104SPaul Moore return ERR_CAST(filename); 344651689104SPaul Moore 34479883d185SAl Viro set_nameidata(&nd, -1, filename); 3448c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_RCU); 344973d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 3450c8a53ee5SAl Viro file = path_openat(&nd, op, flags); 345173d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 3452c8a53ee5SAl Viro file = path_openat(&nd, op, flags | LOOKUP_REVAL); 34539883d185SAl Viro restore_nameidata(); 345451689104SPaul Moore putname(filename); 345573d049a4SAl Viro return file; 345673d049a4SAl Viro } 345773d049a4SAl Viro 3458fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 34591ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 34601da177e4SLinus Torvalds { 3461c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3462391172c4SAl Viro struct qstr last; 3463391172c4SAl Viro int type; 3464c30dabfeSJan Kara int err2; 34651ac12b4bSJeff Layton int error; 34661ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 34671ac12b4bSJeff Layton 34681ac12b4bSJeff Layton /* 34691ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 34701ac12b4bSJeff Layton * other flags passed in are ignored! 34711ac12b4bSJeff Layton */ 34721ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 34731ac12b4bSJeff Layton 34745c31b6ceSAl Viro name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); 34755c31b6ceSAl Viro if (IS_ERR(name)) 34765c31b6ceSAl Viro return ERR_CAST(name); 34771da177e4SLinus Torvalds 3478c663e5d8SChristoph Hellwig /* 3479c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3480c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3481c663e5d8SChristoph Hellwig */ 34825c31b6ceSAl Viro if (unlikely(type != LAST_NORM)) 3483ed75e95dSAl Viro goto out; 3484c663e5d8SChristoph Hellwig 3485c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3486391172c4SAl Viro err2 = mnt_want_write(path->mnt); 3487c663e5d8SChristoph Hellwig /* 3488c663e5d8SChristoph Hellwig * Do the final lookup. 3489c663e5d8SChristoph Hellwig */ 3490391172c4SAl Viro lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; 34915955102cSAl Viro inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); 3492391172c4SAl Viro dentry = __lookup_hash(&last, path->dentry, lookup_flags); 34931da177e4SLinus Torvalds if (IS_ERR(dentry)) 3494a8104a9fSAl Viro goto unlock; 3495c663e5d8SChristoph Hellwig 3496a8104a9fSAl Viro error = -EEXIST; 3497b18825a7SDavid Howells if (d_is_positive(dentry)) 3498a8104a9fSAl Viro goto fail; 3499b18825a7SDavid Howells 3500c663e5d8SChristoph Hellwig /* 3501c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3502c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3503c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3504c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3505c663e5d8SChristoph Hellwig */ 3506391172c4SAl Viro if (unlikely(!is_dir && last.name[last.len])) { 3507a8104a9fSAl Viro error = -ENOENT; 3508ed75e95dSAl Viro goto fail; 3509e9baf6e5SAl Viro } 3510c30dabfeSJan Kara if (unlikely(err2)) { 3511c30dabfeSJan Kara error = err2; 3512a8104a9fSAl Viro goto fail; 3513c30dabfeSJan Kara } 3514181c37b6SAl Viro putname(name); 3515e9baf6e5SAl Viro return dentry; 35161da177e4SLinus Torvalds fail: 3517a8104a9fSAl Viro dput(dentry); 3518a8104a9fSAl Viro dentry = ERR_PTR(error); 3519a8104a9fSAl Viro unlock: 35205955102cSAl Viro inode_unlock(path->dentry->d_inode); 3521c30dabfeSJan Kara if (!err2) 3522391172c4SAl Viro mnt_drop_write(path->mnt); 3523ed75e95dSAl Viro out: 3524391172c4SAl Viro path_put(path); 3525181c37b6SAl Viro putname(name); 3526ed75e95dSAl Viro return dentry; 3527dae6ad8fSAl Viro } 3528fa14a0b8SAl Viro 3529fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3530fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3531fa14a0b8SAl Viro { 3532181c37b6SAl Viro return filename_create(dfd, getname_kernel(pathname), 3533181c37b6SAl Viro path, lookup_flags); 3534fa14a0b8SAl Viro } 3535dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3536dae6ad8fSAl Viro 3537921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3538921a1650SAl Viro { 3539921a1650SAl Viro dput(dentry); 35405955102cSAl Viro inode_unlock(path->dentry->d_inode); 3541a8104a9fSAl Viro mnt_drop_write(path->mnt); 3542921a1650SAl Viro path_put(path); 3543921a1650SAl Viro } 3544921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3545921a1650SAl Viro 3546520ae687SAl Viro inline struct dentry *user_path_create(int dfd, const char __user *pathname, 35471ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3548dae6ad8fSAl Viro { 3549181c37b6SAl Viro return filename_create(dfd, getname(pathname), path, lookup_flags); 3550dae6ad8fSAl Viro } 3551dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3552dae6ad8fSAl Viro 35531a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 35541da177e4SLinus Torvalds { 3555a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35561da177e4SLinus Torvalds 35571da177e4SLinus Torvalds if (error) 35581da177e4SLinus Torvalds return error; 35591da177e4SLinus Torvalds 356094f82008SChristian Brauner if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 35611da177e4SLinus Torvalds return -EPERM; 35621da177e4SLinus Torvalds 3563acfa4380SAl Viro if (!dir->i_op->mknod) 35641da177e4SLinus Torvalds return -EPERM; 35651da177e4SLinus Torvalds 356608ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 356708ce5f16SSerge E. Hallyn if (error) 356808ce5f16SSerge E. Hallyn return error; 356908ce5f16SSerge E. Hallyn 35701da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 35711da177e4SLinus Torvalds if (error) 35721da177e4SLinus Torvalds return error; 35731da177e4SLinus Torvalds 35741da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3575a74574aaSStephen Smalley if (!error) 3576f38aa942SAmy Griffis fsnotify_create(dir, dentry); 35771da177e4SLinus Torvalds return error; 35781da177e4SLinus Torvalds } 35794d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 35801da177e4SLinus Torvalds 3581f69aac00SAl Viro static int may_mknod(umode_t mode) 3582463c3197SDave Hansen { 3583463c3197SDave Hansen switch (mode & S_IFMT) { 3584463c3197SDave Hansen case S_IFREG: 3585463c3197SDave Hansen case S_IFCHR: 3586463c3197SDave Hansen case S_IFBLK: 3587463c3197SDave Hansen case S_IFIFO: 3588463c3197SDave Hansen case S_IFSOCK: 3589463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3590463c3197SDave Hansen return 0; 3591463c3197SDave Hansen case S_IFDIR: 3592463c3197SDave Hansen return -EPERM; 3593463c3197SDave Hansen default: 3594463c3197SDave Hansen return -EINVAL; 3595463c3197SDave Hansen } 3596463c3197SDave Hansen } 3597463c3197SDave Hansen 359887c4e192SDominik Brodowski long do_mknodat(int dfd, const char __user *filename, umode_t mode, 359987c4e192SDominik Brodowski unsigned int dev) 36001da177e4SLinus Torvalds { 36011da177e4SLinus Torvalds struct dentry *dentry; 3602dae6ad8fSAl Viro struct path path; 3603dae6ad8fSAl Viro int error; 3604972567f1SJeff Layton unsigned int lookup_flags = 0; 36051da177e4SLinus Torvalds 36068e4bfca1SAl Viro error = may_mknod(mode); 36078e4bfca1SAl Viro if (error) 36088e4bfca1SAl Viro return error; 3609972567f1SJeff Layton retry: 3610972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3611dae6ad8fSAl Viro if (IS_ERR(dentry)) 3612dae6ad8fSAl Viro return PTR_ERR(dentry); 36132ad94ae6SAl Viro 3614dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3615ce3b0f8dSAl Viro mode &= ~current_umask(); 3616dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3617be6d3e56SKentaro Takeda if (error) 3618a8104a9fSAl Viro goto out; 36191da177e4SLinus Torvalds switch (mode & S_IFMT) { 36201da177e4SLinus Torvalds case 0: case S_IFREG: 3621312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 362205d1a717SMimi Zohar if (!error) 362305d1a717SMimi Zohar ima_post_path_mknod(dentry); 36241da177e4SLinus Torvalds break; 36251da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3626dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 36271da177e4SLinus Torvalds new_decode_dev(dev)); 36281da177e4SLinus Torvalds break; 36291da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3630dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 36311da177e4SLinus Torvalds break; 36321da177e4SLinus Torvalds } 3633a8104a9fSAl Viro out: 3634921a1650SAl Viro done_path_create(&path, dentry); 3635972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3636972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3637972567f1SJeff Layton goto retry; 3638972567f1SJeff Layton } 36391da177e4SLinus Torvalds return error; 36401da177e4SLinus Torvalds } 36411da177e4SLinus Torvalds 364287c4e192SDominik Brodowski SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 364387c4e192SDominik Brodowski unsigned int, dev) 364487c4e192SDominik Brodowski { 364587c4e192SDominik Brodowski return do_mknodat(dfd, filename, mode, dev); 364687c4e192SDominik Brodowski } 364787c4e192SDominik Brodowski 36488208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 36495590ff0dSUlrich Drepper { 365087c4e192SDominik Brodowski return do_mknodat(AT_FDCWD, filename, mode, dev); 36515590ff0dSUlrich Drepper } 36525590ff0dSUlrich Drepper 365318bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 36541da177e4SLinus Torvalds { 3655a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 36568de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 36571da177e4SLinus Torvalds 36581da177e4SLinus Torvalds if (error) 36591da177e4SLinus Torvalds return error; 36601da177e4SLinus Torvalds 3661acfa4380SAl Viro if (!dir->i_op->mkdir) 36621da177e4SLinus Torvalds return -EPERM; 36631da177e4SLinus Torvalds 36641da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 36651da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 36661da177e4SLinus Torvalds if (error) 36671da177e4SLinus Torvalds return error; 36681da177e4SLinus Torvalds 36698de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 36708de52778SAl Viro return -EMLINK; 36718de52778SAl Viro 36721da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3673a74574aaSStephen Smalley if (!error) 3674f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 36751da177e4SLinus Torvalds return error; 36761da177e4SLinus Torvalds } 36774d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 36781da177e4SLinus Torvalds 36790101db7aSDominik Brodowski long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) 36801da177e4SLinus Torvalds { 36816902d925SDave Hansen struct dentry *dentry; 3682dae6ad8fSAl Viro struct path path; 3683dae6ad8fSAl Viro int error; 3684b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 36851da177e4SLinus Torvalds 3686b76d8b82SJeff Layton retry: 3687b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 36886902d925SDave Hansen if (IS_ERR(dentry)) 3689dae6ad8fSAl Viro return PTR_ERR(dentry); 36906902d925SDave Hansen 3691dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3692ce3b0f8dSAl Viro mode &= ~current_umask(); 3693dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3694a8104a9fSAl Viro if (!error) 3695dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3696921a1650SAl Viro done_path_create(&path, dentry); 3697b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3698b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3699b76d8b82SJeff Layton goto retry; 3700b76d8b82SJeff Layton } 37011da177e4SLinus Torvalds return error; 37021da177e4SLinus Torvalds } 37031da177e4SLinus Torvalds 37040101db7aSDominik Brodowski SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 37050101db7aSDominik Brodowski { 37060101db7aSDominik Brodowski return do_mkdirat(dfd, pathname, mode); 37070101db7aSDominik Brodowski } 37080101db7aSDominik Brodowski 3709a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 37105590ff0dSUlrich Drepper { 37110101db7aSDominik Brodowski return do_mkdirat(AT_FDCWD, pathname, mode); 37125590ff0dSUlrich Drepper } 37135590ff0dSUlrich Drepper 37141da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 37151da177e4SLinus Torvalds { 37161da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 37171da177e4SLinus Torvalds 37181da177e4SLinus Torvalds if (error) 37191da177e4SLinus Torvalds return error; 37201da177e4SLinus Torvalds 3721acfa4380SAl Viro if (!dir->i_op->rmdir) 37221da177e4SLinus Torvalds return -EPERM; 37231da177e4SLinus Torvalds 37241d2ef590SAl Viro dget(dentry); 37255955102cSAl Viro inode_lock(dentry->d_inode); 3726912dbc15SSage Weil 37271da177e4SLinus Torvalds error = -EBUSY; 37287af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3729912dbc15SSage Weil goto out; 3730912dbc15SSage Weil 37311da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3732912dbc15SSage Weil if (error) 3733912dbc15SSage Weil goto out; 3734912dbc15SSage Weil 37351da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3736912dbc15SSage Weil if (error) 3737912dbc15SSage Weil goto out; 3738912dbc15SSage Weil 37398767712fSAl Viro shrink_dcache_parent(dentry); 37401da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3741d83c49f3SAl Viro dont_mount(dentry); 37428ed936b5SEric W. Biederman detach_mounts(dentry); 3743116b9731SAmir Goldstein fsnotify_rmdir(dir, dentry); 37441da177e4SLinus Torvalds 3745912dbc15SSage Weil out: 37465955102cSAl Viro inode_unlock(dentry->d_inode); 37471d2ef590SAl Viro dput(dentry); 3748912dbc15SSage Weil if (!error) 3749912dbc15SSage Weil d_delete(dentry); 37501da177e4SLinus Torvalds return error; 37511da177e4SLinus Torvalds } 37524d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 37531da177e4SLinus Torvalds 3754f459dffaSDominik Brodowski long do_rmdir(int dfd, const char __user *pathname) 37551da177e4SLinus Torvalds { 37561da177e4SLinus Torvalds int error = 0; 375791a27b2aSJeff Layton struct filename *name; 37581da177e4SLinus Torvalds struct dentry *dentry; 3759f5beed75SAl Viro struct path path; 3760f5beed75SAl Viro struct qstr last; 3761f5beed75SAl Viro int type; 3762c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3763c6ee9206SJeff Layton retry: 3764c1d4dd27SAl Viro name = filename_parentat(dfd, getname(pathname), lookup_flags, 3765c1d4dd27SAl Viro &path, &last, &type); 376691a27b2aSJeff Layton if (IS_ERR(name)) 376791a27b2aSJeff Layton return PTR_ERR(name); 37681da177e4SLinus Torvalds 3769f5beed75SAl Viro switch (type) { 37701da177e4SLinus Torvalds case LAST_DOTDOT: 37711da177e4SLinus Torvalds error = -ENOTEMPTY; 37721da177e4SLinus Torvalds goto exit1; 37731da177e4SLinus Torvalds case LAST_DOT: 37741da177e4SLinus Torvalds error = -EINVAL; 37751da177e4SLinus Torvalds goto exit1; 37761da177e4SLinus Torvalds case LAST_ROOT: 37771da177e4SLinus Torvalds error = -EBUSY; 37781da177e4SLinus Torvalds goto exit1; 37791da177e4SLinus Torvalds } 37800612d9fbSOGAWA Hirofumi 3781f5beed75SAl Viro error = mnt_want_write(path.mnt); 3782c30dabfeSJan Kara if (error) 3783c30dabfeSJan Kara goto exit1; 37840612d9fbSOGAWA Hirofumi 37855955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3786f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 37871da177e4SLinus Torvalds error = PTR_ERR(dentry); 37886902d925SDave Hansen if (IS_ERR(dentry)) 37896902d925SDave Hansen goto exit2; 3790e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3791e6bc45d6STheodore Ts'o error = -ENOENT; 3792e6bc45d6STheodore Ts'o goto exit3; 3793e6bc45d6STheodore Ts'o } 3794f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3795be6d3e56SKentaro Takeda if (error) 3796c30dabfeSJan Kara goto exit3; 3797f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 37980622753bSDave Hansen exit3: 37991da177e4SLinus Torvalds dput(dentry); 38006902d925SDave Hansen exit2: 38015955102cSAl Viro inode_unlock(path.dentry->d_inode); 3802f5beed75SAl Viro mnt_drop_write(path.mnt); 38031da177e4SLinus Torvalds exit1: 3804f5beed75SAl Viro path_put(&path); 38051da177e4SLinus Torvalds putname(name); 3806c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3807c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3808c6ee9206SJeff Layton goto retry; 3809c6ee9206SJeff Layton } 38101da177e4SLinus Torvalds return error; 38111da177e4SLinus Torvalds } 38121da177e4SLinus Torvalds 38133cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 38145590ff0dSUlrich Drepper { 38155590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 38165590ff0dSUlrich Drepper } 38175590ff0dSUlrich Drepper 3818b21996e3SJ. Bruce Fields /** 3819b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3820b21996e3SJ. Bruce Fields * @dir: parent directory 3821b21996e3SJ. Bruce Fields * @dentry: victim 3822b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3823b21996e3SJ. Bruce Fields * 3824b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3825b21996e3SJ. Bruce Fields * 3826b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3827b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3828b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3829b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3830b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3831b21996e3SJ. Bruce Fields * 3832b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3833b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3834b21996e3SJ. Bruce Fields * to be NFS exported. 3835b21996e3SJ. Bruce Fields */ 3836b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 38371da177e4SLinus Torvalds { 38389accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 38391da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 38401da177e4SLinus Torvalds 38411da177e4SLinus Torvalds if (error) 38421da177e4SLinus Torvalds return error; 38431da177e4SLinus Torvalds 3844acfa4380SAl Viro if (!dir->i_op->unlink) 38451da177e4SLinus Torvalds return -EPERM; 38461da177e4SLinus Torvalds 38475955102cSAl Viro inode_lock(target); 38488ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 38491da177e4SLinus Torvalds error = -EBUSY; 38501da177e4SLinus Torvalds else { 38511da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3852bec1052eSAl Viro if (!error) { 38535a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 38545a14696cSJ. Bruce Fields if (error) 3855b21996e3SJ. Bruce Fields goto out; 38561da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 38578ed936b5SEric W. Biederman if (!error) { 3858d83c49f3SAl Viro dont_mount(dentry); 38598ed936b5SEric W. Biederman detach_mounts(dentry); 3860116b9731SAmir Goldstein fsnotify_unlink(dir, dentry); 38618ed936b5SEric W. Biederman } 3862bec1052eSAl Viro } 38631da177e4SLinus Torvalds } 3864b21996e3SJ. Bruce Fields out: 38655955102cSAl Viro inode_unlock(target); 38661da177e4SLinus Torvalds 38671da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 38681da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 38699accbb97SJ. Bruce Fields fsnotify_link_count(target); 38701da177e4SLinus Torvalds d_delete(dentry); 38711da177e4SLinus Torvalds } 38720eeca283SRobert Love 38731da177e4SLinus Torvalds return error; 38741da177e4SLinus Torvalds } 38754d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 38761da177e4SLinus Torvalds 38771da177e4SLinus Torvalds /* 38781da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 38791b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 38801da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 38811da177e4SLinus Torvalds * while waiting on the I/O. 38821da177e4SLinus Torvalds */ 3883da2f1362SChristoph Hellwig long do_unlinkat(int dfd, struct filename *name) 38841da177e4SLinus Torvalds { 38852ad94ae6SAl Viro int error; 38861da177e4SLinus Torvalds struct dentry *dentry; 3887f5beed75SAl Viro struct path path; 3888f5beed75SAl Viro struct qstr last; 3889f5beed75SAl Viro int type; 38901da177e4SLinus Torvalds struct inode *inode = NULL; 3891b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 38925d18f813SJeff Layton unsigned int lookup_flags = 0; 38935d18f813SJeff Layton retry: 3894da2f1362SChristoph Hellwig name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); 389591a27b2aSJeff Layton if (IS_ERR(name)) 389691a27b2aSJeff Layton return PTR_ERR(name); 38972ad94ae6SAl Viro 38981da177e4SLinus Torvalds error = -EISDIR; 3899f5beed75SAl Viro if (type != LAST_NORM) 39001da177e4SLinus Torvalds goto exit1; 39010612d9fbSOGAWA Hirofumi 3902f5beed75SAl Viro error = mnt_want_write(path.mnt); 3903c30dabfeSJan Kara if (error) 3904c30dabfeSJan Kara goto exit1; 3905b21996e3SJ. Bruce Fields retry_deleg: 39065955102cSAl Viro inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); 3907f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 39081da177e4SLinus Torvalds error = PTR_ERR(dentry); 39091da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 39101da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3911f5beed75SAl Viro if (last.name[last.len]) 391250338b88STörök Edwin goto slashes; 39131da177e4SLinus Torvalds inode = dentry->d_inode; 3914b18825a7SDavid Howells if (d_is_negative(dentry)) 3915e6bc45d6STheodore Ts'o goto slashes; 39167de9c6eeSAl Viro ihold(inode); 3917f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3918be6d3e56SKentaro Takeda if (error) 3919c30dabfeSJan Kara goto exit2; 3920f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 39211da177e4SLinus Torvalds exit2: 39221da177e4SLinus Torvalds dput(dentry); 39231da177e4SLinus Torvalds } 39245955102cSAl Viro inode_unlock(path.dentry->d_inode); 39251da177e4SLinus Torvalds if (inode) 39261da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3927b21996e3SJ. Bruce Fields inode = NULL; 3928b21996e3SJ. Bruce Fields if (delegated_inode) { 39295a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3930b21996e3SJ. Bruce Fields if (!error) 3931b21996e3SJ. Bruce Fields goto retry_deleg; 3932b21996e3SJ. Bruce Fields } 3933f5beed75SAl Viro mnt_drop_write(path.mnt); 39341da177e4SLinus Torvalds exit1: 3935f5beed75SAl Viro path_put(&path); 39365d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 39375d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 39385d18f813SJeff Layton inode = NULL; 39395d18f813SJeff Layton goto retry; 39405d18f813SJeff Layton } 3941da2f1362SChristoph Hellwig putname(name); 39421da177e4SLinus Torvalds return error; 39431da177e4SLinus Torvalds 39441da177e4SLinus Torvalds slashes: 3945b18825a7SDavid Howells if (d_is_negative(dentry)) 3946b18825a7SDavid Howells error = -ENOENT; 394744b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3948b18825a7SDavid Howells error = -EISDIR; 3949b18825a7SDavid Howells else 3950b18825a7SDavid Howells error = -ENOTDIR; 39511da177e4SLinus Torvalds goto exit2; 39521da177e4SLinus Torvalds } 39531da177e4SLinus Torvalds 39542e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 39555590ff0dSUlrich Drepper { 39565590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 39575590ff0dSUlrich Drepper return -EINVAL; 39585590ff0dSUlrich Drepper 39595590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 39605590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 39615590ff0dSUlrich Drepper 3962da2f1362SChristoph Hellwig return do_unlinkat(dfd, getname(pathname)); 39635590ff0dSUlrich Drepper } 39645590ff0dSUlrich Drepper 39653480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 39665590ff0dSUlrich Drepper { 3967da2f1362SChristoph Hellwig return do_unlinkat(AT_FDCWD, getname(pathname)); 39685590ff0dSUlrich Drepper } 39695590ff0dSUlrich Drepper 3970db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 39711da177e4SLinus Torvalds { 3972a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 39731da177e4SLinus Torvalds 39741da177e4SLinus Torvalds if (error) 39751da177e4SLinus Torvalds return error; 39761da177e4SLinus Torvalds 3977acfa4380SAl Viro if (!dir->i_op->symlink) 39781da177e4SLinus Torvalds return -EPERM; 39791da177e4SLinus Torvalds 39801da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 39811da177e4SLinus Torvalds if (error) 39821da177e4SLinus Torvalds return error; 39831da177e4SLinus Torvalds 39841da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3985a74574aaSStephen Smalley if (!error) 3986f38aa942SAmy Griffis fsnotify_create(dir, dentry); 39871da177e4SLinus Torvalds return error; 39881da177e4SLinus Torvalds } 39894d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 39901da177e4SLinus Torvalds 3991b724e846SDominik Brodowski long do_symlinkat(const char __user *oldname, int newdfd, 3992b724e846SDominik Brodowski const char __user *newname) 39931da177e4SLinus Torvalds { 39942ad94ae6SAl Viro int error; 399591a27b2aSJeff Layton struct filename *from; 39966902d925SDave Hansen struct dentry *dentry; 3997dae6ad8fSAl Viro struct path path; 3998f46d3567SJeff Layton unsigned int lookup_flags = 0; 39991da177e4SLinus Torvalds 40001da177e4SLinus Torvalds from = getname(oldname); 40011da177e4SLinus Torvalds if (IS_ERR(from)) 40021da177e4SLinus Torvalds return PTR_ERR(from); 4003f46d3567SJeff Layton retry: 4004f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 40051da177e4SLinus Torvalds error = PTR_ERR(dentry); 40066902d925SDave Hansen if (IS_ERR(dentry)) 4007dae6ad8fSAl Viro goto out_putname; 40086902d925SDave Hansen 400991a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 4010a8104a9fSAl Viro if (!error) 401191a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 4012921a1650SAl Viro done_path_create(&path, dentry); 4013f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 4014f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 4015f46d3567SJeff Layton goto retry; 4016f46d3567SJeff Layton } 40176902d925SDave Hansen out_putname: 40181da177e4SLinus Torvalds putname(from); 40191da177e4SLinus Torvalds return error; 40201da177e4SLinus Torvalds } 40211da177e4SLinus Torvalds 4022b724e846SDominik Brodowski SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 4023b724e846SDominik Brodowski int, newdfd, const char __user *, newname) 4024b724e846SDominik Brodowski { 4025b724e846SDominik Brodowski return do_symlinkat(oldname, newdfd, newname); 4026b724e846SDominik Brodowski } 4027b724e846SDominik Brodowski 40283480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 40295590ff0dSUlrich Drepper { 4030b724e846SDominik Brodowski return do_symlinkat(oldname, AT_FDCWD, newname); 40315590ff0dSUlrich Drepper } 40325590ff0dSUlrich Drepper 4033146a8595SJ. Bruce Fields /** 4034146a8595SJ. Bruce Fields * vfs_link - create a new link 4035146a8595SJ. Bruce Fields * @old_dentry: object to be linked 4036146a8595SJ. Bruce Fields * @dir: new parent 4037146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 4038146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 4039146a8595SJ. Bruce Fields * 4040146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 4041146a8595SJ. Bruce Fields * 4042146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 4043146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 4044146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 4045146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 4046146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 4047146a8595SJ. Bruce Fields * 4048146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 4049146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 4050146a8595SJ. Bruce Fields * to be NFS exported. 4051146a8595SJ. Bruce Fields */ 4052146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 40531da177e4SLinus Torvalds { 40541da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 40558de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 40561da177e4SLinus Torvalds int error; 40571da177e4SLinus Torvalds 40581da177e4SLinus Torvalds if (!inode) 40591da177e4SLinus Torvalds return -ENOENT; 40601da177e4SLinus Torvalds 4061a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 40621da177e4SLinus Torvalds if (error) 40631da177e4SLinus Torvalds return error; 40641da177e4SLinus Torvalds 40651da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 40661da177e4SLinus Torvalds return -EXDEV; 40671da177e4SLinus Torvalds 40681da177e4SLinus Torvalds /* 40691da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 40701da177e4SLinus Torvalds */ 40711da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 40721da177e4SLinus Torvalds return -EPERM; 40730bd23d09SEric W. Biederman /* 40740bd23d09SEric W. Biederman * Updating the link count will likely cause i_uid and i_gid to 40750bd23d09SEric W. Biederman * be writen back improperly if their true value is unknown to 40760bd23d09SEric W. Biederman * the vfs. 40770bd23d09SEric W. Biederman */ 40780bd23d09SEric W. Biederman if (HAS_UNMAPPED_ID(inode)) 40790bd23d09SEric W. Biederman return -EPERM; 4080acfa4380SAl Viro if (!dir->i_op->link) 40811da177e4SLinus Torvalds return -EPERM; 40827e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 40831da177e4SLinus Torvalds return -EPERM; 40841da177e4SLinus Torvalds 40851da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 40861da177e4SLinus Torvalds if (error) 40871da177e4SLinus Torvalds return error; 40881da177e4SLinus Torvalds 40895955102cSAl Viro inode_lock(inode); 4090aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 4091f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 4092aae8a97dSAneesh Kumar K.V error = -ENOENT; 40938de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 40948de52778SAl Viro error = -EMLINK; 4095146a8595SJ. Bruce Fields else { 4096146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 4097146a8595SJ. Bruce Fields if (!error) 40981da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 4099146a8595SJ. Bruce Fields } 4100f4e0c30cSAl Viro 4101f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 4102f4e0c30cSAl Viro spin_lock(&inode->i_lock); 4103f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 4104f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 4105f4e0c30cSAl Viro } 41065955102cSAl Viro inode_unlock(inode); 4107e31e14ecSStephen Smalley if (!error) 41087e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 41091da177e4SLinus Torvalds return error; 41101da177e4SLinus Torvalds } 41114d359507SAl Viro EXPORT_SYMBOL(vfs_link); 41121da177e4SLinus Torvalds 41131da177e4SLinus Torvalds /* 41141da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 41151da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 41161da177e4SLinus Torvalds * newname. --KAB 41171da177e4SLinus Torvalds * 41181da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 41191da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 41201da177e4SLinus Torvalds * and other special files. --ADM 41211da177e4SLinus Torvalds */ 412246ea89ebSDominik Brodowski int do_linkat(int olddfd, const char __user *oldname, int newdfd, 412346ea89ebSDominik Brodowski const char __user *newname, int flags) 41241da177e4SLinus Torvalds { 41251da177e4SLinus Torvalds struct dentry *new_dentry; 4126dae6ad8fSAl Viro struct path old_path, new_path; 4127146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 412811a7b371SAneesh Kumar K.V int how = 0; 41291da177e4SLinus Torvalds int error; 41301da177e4SLinus Torvalds 413111a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4132c04030e1SUlrich Drepper return -EINVAL; 413311a7b371SAneesh Kumar K.V /* 4134f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4135f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4136f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 413711a7b371SAneesh Kumar K.V */ 4138f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4139f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4140f0cc6ffbSLinus Torvalds return -ENOENT; 414111a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4142f0cc6ffbSLinus Torvalds } 4143c04030e1SUlrich Drepper 414411a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 414511a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4146442e31caSJeff Layton retry: 414711a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 41481da177e4SLinus Torvalds if (error) 41492ad94ae6SAl Viro return error; 41502ad94ae6SAl Viro 4151442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4152442e31caSJeff Layton (how & LOOKUP_REVAL)); 41531da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 41546902d925SDave Hansen if (IS_ERR(new_dentry)) 4155dae6ad8fSAl Viro goto out; 4156dae6ad8fSAl Viro 4157dae6ad8fSAl Viro error = -EXDEV; 4158dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4159dae6ad8fSAl Viro goto out_dput; 4160800179c9SKees Cook error = may_linkat(&old_path); 4161800179c9SKees Cook if (unlikely(error)) 4162800179c9SKees Cook goto out_dput; 4163dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4164be6d3e56SKentaro Takeda if (error) 4165a8104a9fSAl Viro goto out_dput; 4166146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 416775c3f29dSDave Hansen out_dput: 4168921a1650SAl Viro done_path_create(&new_path, new_dentry); 4169146a8595SJ. Bruce Fields if (delegated_inode) { 4170146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4171d22e6338SOleg Drokin if (!error) { 4172d22e6338SOleg Drokin path_put(&old_path); 4173146a8595SJ. Bruce Fields goto retry; 4174146a8595SJ. Bruce Fields } 4175d22e6338SOleg Drokin } 4176442e31caSJeff Layton if (retry_estale(error, how)) { 4177d22e6338SOleg Drokin path_put(&old_path); 4178442e31caSJeff Layton how |= LOOKUP_REVAL; 4179442e31caSJeff Layton goto retry; 4180442e31caSJeff Layton } 41811da177e4SLinus Torvalds out: 41822d8f3038SAl Viro path_put(&old_path); 41831da177e4SLinus Torvalds 41841da177e4SLinus Torvalds return error; 41851da177e4SLinus Torvalds } 41861da177e4SLinus Torvalds 418746ea89ebSDominik Brodowski SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 418846ea89ebSDominik Brodowski int, newdfd, const char __user *, newname, int, flags) 418946ea89ebSDominik Brodowski { 419046ea89ebSDominik Brodowski return do_linkat(olddfd, oldname, newdfd, newname, flags); 419146ea89ebSDominik Brodowski } 419246ea89ebSDominik Brodowski 41933480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 41945590ff0dSUlrich Drepper { 419546ea89ebSDominik Brodowski return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 41965590ff0dSUlrich Drepper } 41975590ff0dSUlrich Drepper 4198bc27027aSMiklos Szeredi /** 4199bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4200bc27027aSMiklos Szeredi * @old_dir: parent of source 4201bc27027aSMiklos Szeredi * @old_dentry: source 4202bc27027aSMiklos Szeredi * @new_dir: parent of destination 4203bc27027aSMiklos Szeredi * @new_dentry: destination 4204bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4205520c8b16SMiklos Szeredi * @flags: rename flags 4206bc27027aSMiklos Szeredi * 4207bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4208bc27027aSMiklos Szeredi * 4209bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4210bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4211bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4212bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4213bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4214bc27027aSMiklos Szeredi * so. 4215bc27027aSMiklos Szeredi * 4216bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4217bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4218bc27027aSMiklos Szeredi * to be NFS exported. 4219bc27027aSMiklos Szeredi * 42201da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 42211da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 42221da177e4SLinus Torvalds * Problems: 42230117d427SMauro Carvalho Chehab * 4224d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 42251da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 42261da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4227a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 42281da177e4SLinus Torvalds * story. 42296cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 42306cedba89SJ. Bruce Fields * and source (if it is not a directory). 42311b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 42321da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 42331da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4234a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 42351da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 42361da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 42371da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4238a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 42391da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 42401da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 42411da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4242e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 42431b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 42441da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4245c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 42461da177e4SLinus Torvalds * locking]. 42471da177e4SLinus Torvalds */ 42481da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 42498e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4250520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 42511da177e4SLinus Torvalds { 42521da177e4SLinus Torvalds int error; 4253bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 4254bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4255bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4256da1ce067SMiklos Szeredi bool new_is_dir = false; 4257da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 425849d31c2fSAl Viro struct name_snapshot old_name; 42591da177e4SLinus Torvalds 42608d3e2936SMiklos Szeredi if (source == target) 42611da177e4SLinus Torvalds return 0; 42621da177e4SLinus Torvalds 42631da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 42641da177e4SLinus Torvalds if (error) 42651da177e4SLinus Torvalds return error; 42661da177e4SLinus Torvalds 4267da1ce067SMiklos Szeredi if (!target) { 4268a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4269da1ce067SMiklos Szeredi } else { 4270da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4271da1ce067SMiklos Szeredi 4272da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 42731da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4274da1ce067SMiklos Szeredi else 4275da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4276da1ce067SMiklos Szeredi } 42771da177e4SLinus Torvalds if (error) 42781da177e4SLinus Torvalds return error; 42791da177e4SLinus Torvalds 42802773bf00SMiklos Szeredi if (!old_dir->i_op->rename) 42811da177e4SLinus Torvalds return -EPERM; 42821da177e4SLinus Torvalds 4283bc27027aSMiklos Szeredi /* 4284bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4285bc27027aSMiklos Szeredi * we'll need to flip '..'. 4286bc27027aSMiklos Szeredi */ 4287da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4288da1ce067SMiklos Szeredi if (is_dir) { 4289bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4290bc27027aSMiklos Szeredi if (error) 4291bc27027aSMiklos Szeredi return error; 4292bc27027aSMiklos Szeredi } 4293da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4294da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4295da1ce067SMiklos Szeredi if (error) 4296da1ce067SMiklos Szeredi return error; 4297da1ce067SMiklos Szeredi } 4298da1ce067SMiklos Szeredi } 42990eeca283SRobert Love 43000b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 43010b3974ebSMiklos Szeredi flags); 4302bc27027aSMiklos Szeredi if (error) 4303bc27027aSMiklos Szeredi return error; 4304bc27027aSMiklos Szeredi 430549d31c2fSAl Viro take_dentry_name_snapshot(&old_name, old_dentry); 4306bc27027aSMiklos Szeredi dget(new_dentry); 4307da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4308bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4309bc27027aSMiklos Szeredi else if (target) 43105955102cSAl Viro inode_lock(target); 4311bc27027aSMiklos Szeredi 4312bc27027aSMiklos Szeredi error = -EBUSY; 43137af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4314bc27027aSMiklos Szeredi goto out; 4315bc27027aSMiklos Szeredi 4316da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4317bc27027aSMiklos Szeredi error = -EMLINK; 4318da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4319bc27027aSMiklos Szeredi goto out; 4320da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4321da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4322da1ce067SMiklos Szeredi goto out; 4323da1ce067SMiklos Szeredi } 4324da1ce067SMiklos Szeredi if (!is_dir) { 4325bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4326bc27027aSMiklos Szeredi if (error) 4327bc27027aSMiklos Szeredi goto out; 4328da1ce067SMiklos Szeredi } 4329da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4330bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4331bc27027aSMiklos Szeredi if (error) 4332bc27027aSMiklos Szeredi goto out; 4333bc27027aSMiklos Szeredi } 4334520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4335520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4336bc27027aSMiklos Szeredi if (error) 4337bc27027aSMiklos Szeredi goto out; 4338bc27027aSMiklos Szeredi 4339da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 43408767712fSAl Viro if (is_dir) { 43418767712fSAl Viro shrink_dcache_parent(new_dentry); 4342bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 43438767712fSAl Viro } 4344bc27027aSMiklos Szeredi dont_mount(new_dentry); 43458ed936b5SEric W. Biederman detach_mounts(new_dentry); 4346bc27027aSMiklos Szeredi } 4347da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4348da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4349bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4350da1ce067SMiklos Szeredi else 4351da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4352da1ce067SMiklos Szeredi } 4353bc27027aSMiklos Szeredi out: 4354da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4355bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4356bc27027aSMiklos Szeredi else if (target) 43575955102cSAl Viro inode_unlock(target); 4358bc27027aSMiklos Szeredi dput(new_dentry); 4359da1ce067SMiklos Szeredi if (!error) { 4360f4ec3a3dSAl Viro fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, 4361da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4362da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4363f4ec3a3dSAl Viro fsnotify_move(new_dir, old_dir, &old_dentry->d_name, 4364da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4365da1ce067SMiklos Szeredi } 4366da1ce067SMiklos Szeredi } 436749d31c2fSAl Viro release_dentry_name_snapshot(&old_name); 43680eeca283SRobert Love 43691da177e4SLinus Torvalds return error; 43701da177e4SLinus Torvalds } 43714d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 43721da177e4SLinus Torvalds 4373ee81feb6SDominik Brodowski static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, 4374ee81feb6SDominik Brodowski const char __user *newname, unsigned int flags) 43751da177e4SLinus Torvalds { 43761da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 43771da177e4SLinus Torvalds struct dentry *trap; 4378f5beed75SAl Viro struct path old_path, new_path; 4379f5beed75SAl Viro struct qstr old_last, new_last; 4380f5beed75SAl Viro int old_type, new_type; 43818e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 438291a27b2aSJeff Layton struct filename *from; 438391a27b2aSJeff Layton struct filename *to; 4384f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4385c6a94284SJeff Layton bool should_retry = false; 43862ad94ae6SAl Viro int error; 4387520c8b16SMiklos Szeredi 43880d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4389da1ce067SMiklos Szeredi return -EINVAL; 4390da1ce067SMiklos Szeredi 43910d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 43920d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4393520c8b16SMiklos Szeredi return -EINVAL; 4394520c8b16SMiklos Szeredi 43950d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 43960d7a8555SMiklos Szeredi return -EPERM; 43970d7a8555SMiklos Szeredi 4398f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4399f5beed75SAl Viro target_flags = 0; 4400f5beed75SAl Viro 4401c6a94284SJeff Layton retry: 4402c1d4dd27SAl Viro from = filename_parentat(olddfd, getname(oldname), lookup_flags, 4403c1d4dd27SAl Viro &old_path, &old_last, &old_type); 440491a27b2aSJeff Layton if (IS_ERR(from)) { 440591a27b2aSJeff Layton error = PTR_ERR(from); 44061da177e4SLinus Torvalds goto exit; 440791a27b2aSJeff Layton } 44081da177e4SLinus Torvalds 4409c1d4dd27SAl Viro to = filename_parentat(newdfd, getname(newname), lookup_flags, 4410c1d4dd27SAl Viro &new_path, &new_last, &new_type); 441191a27b2aSJeff Layton if (IS_ERR(to)) { 441291a27b2aSJeff Layton error = PTR_ERR(to); 44131da177e4SLinus Torvalds goto exit1; 441491a27b2aSJeff Layton } 44151da177e4SLinus Torvalds 44161da177e4SLinus Torvalds error = -EXDEV; 4417f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 44181da177e4SLinus Torvalds goto exit2; 44191da177e4SLinus Torvalds 44201da177e4SLinus Torvalds error = -EBUSY; 4421f5beed75SAl Viro if (old_type != LAST_NORM) 44221da177e4SLinus Torvalds goto exit2; 44231da177e4SLinus Torvalds 44240a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 44250a7c3937SMiklos Szeredi error = -EEXIST; 4426f5beed75SAl Viro if (new_type != LAST_NORM) 44271da177e4SLinus Torvalds goto exit2; 44281da177e4SLinus Torvalds 4429f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4430c30dabfeSJan Kara if (error) 4431c30dabfeSJan Kara goto exit2; 4432c30dabfeSJan Kara 44338e6d782cSJ. Bruce Fields retry_deleg: 4434f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 44351da177e4SLinus Torvalds 4436f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 44371da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 44381da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 44391da177e4SLinus Torvalds goto exit3; 44401da177e4SLinus Torvalds /* source must exist */ 44411da177e4SLinus Torvalds error = -ENOENT; 4442b18825a7SDavid Howells if (d_is_negative(old_dentry)) 44431da177e4SLinus Torvalds goto exit4; 4444f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 44451da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 44461da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 44471da177e4SLinus Torvalds goto exit4; 44480a7c3937SMiklos Szeredi error = -EEXIST; 44490a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 44500a7c3937SMiklos Szeredi goto exit5; 4451da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4452da1ce067SMiklos Szeredi error = -ENOENT; 4453da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4454da1ce067SMiklos Szeredi goto exit5; 4455da1ce067SMiklos Szeredi 4456da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4457da1ce067SMiklos Szeredi error = -ENOTDIR; 4458f5beed75SAl Viro if (new_last.name[new_last.len]) 4459da1ce067SMiklos Szeredi goto exit5; 4460da1ce067SMiklos Szeredi } 4461da1ce067SMiklos Szeredi } 44620a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 44630a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 44640a7c3937SMiklos Szeredi error = -ENOTDIR; 4465f5beed75SAl Viro if (old_last.name[old_last.len]) 44660a7c3937SMiklos Szeredi goto exit5; 4467f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 44680a7c3937SMiklos Szeredi goto exit5; 44690a7c3937SMiklos Szeredi } 44700a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 44710a7c3937SMiklos Szeredi error = -EINVAL; 44720a7c3937SMiklos Szeredi if (old_dentry == trap) 44730a7c3937SMiklos Szeredi goto exit5; 44741da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4475da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 44761da177e4SLinus Torvalds error = -ENOTEMPTY; 44771da177e4SLinus Torvalds if (new_dentry == trap) 44781da177e4SLinus Torvalds goto exit5; 44791da177e4SLinus Torvalds 4480f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4481f5beed75SAl Viro &new_path, new_dentry, flags); 4482be6d3e56SKentaro Takeda if (error) 4483c30dabfeSJan Kara goto exit5; 4484f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4485f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4486520c8b16SMiklos Szeredi &delegated_inode, flags); 44871da177e4SLinus Torvalds exit5: 44881da177e4SLinus Torvalds dput(new_dentry); 44891da177e4SLinus Torvalds exit4: 44901da177e4SLinus Torvalds dput(old_dentry); 44911da177e4SLinus Torvalds exit3: 4492f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 44938e6d782cSJ. Bruce Fields if (delegated_inode) { 44948e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 44958e6d782cSJ. Bruce Fields if (!error) 44968e6d782cSJ. Bruce Fields goto retry_deleg; 44978e6d782cSJ. Bruce Fields } 4498f5beed75SAl Viro mnt_drop_write(old_path.mnt); 44991da177e4SLinus Torvalds exit2: 4500c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4501c6a94284SJeff Layton should_retry = true; 4502f5beed75SAl Viro path_put(&new_path); 45032ad94ae6SAl Viro putname(to); 45041da177e4SLinus Torvalds exit1: 4505f5beed75SAl Viro path_put(&old_path); 45061da177e4SLinus Torvalds putname(from); 4507c6a94284SJeff Layton if (should_retry) { 4508c6a94284SJeff Layton should_retry = false; 4509c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4510c6a94284SJeff Layton goto retry; 4511c6a94284SJeff Layton } 45122ad94ae6SAl Viro exit: 45131da177e4SLinus Torvalds return error; 45141da177e4SLinus Torvalds } 45151da177e4SLinus Torvalds 4516ee81feb6SDominik Brodowski SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4517ee81feb6SDominik Brodowski int, newdfd, const char __user *, newname, unsigned int, flags) 4518ee81feb6SDominik Brodowski { 4519ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, flags); 4520ee81feb6SDominik Brodowski } 4521ee81feb6SDominik Brodowski 4522520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4523520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4524520c8b16SMiklos Szeredi { 4525ee81feb6SDominik Brodowski return do_renameat2(olddfd, oldname, newdfd, newname, 0); 4526520c8b16SMiklos Szeredi } 4527520c8b16SMiklos Szeredi 4528a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 45295590ff0dSUlrich Drepper { 4530ee81feb6SDominik Brodowski return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 45315590ff0dSUlrich Drepper } 45325590ff0dSUlrich Drepper 4533787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4534787fb6bcSMiklos Szeredi { 4535787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4536787fb6bcSMiklos Szeredi if (error) 4537787fb6bcSMiklos Szeredi return error; 4538787fb6bcSMiklos Szeredi 4539787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4540787fb6bcSMiklos Szeredi return -EPERM; 4541787fb6bcSMiklos Szeredi 4542787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4543787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4544787fb6bcSMiklos Szeredi } 4545787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4546787fb6bcSMiklos Szeredi 45475d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 45481da177e4SLinus Torvalds { 45495d826c84SAl Viro int len = PTR_ERR(link); 45501da177e4SLinus Torvalds if (IS_ERR(link)) 45511da177e4SLinus Torvalds goto out; 45521da177e4SLinus Torvalds 45531da177e4SLinus Torvalds len = strlen(link); 45541da177e4SLinus Torvalds if (len > (unsigned) buflen) 45551da177e4SLinus Torvalds len = buflen; 45561da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 45571da177e4SLinus Torvalds len = -EFAULT; 45581da177e4SLinus Torvalds out: 45591da177e4SLinus Torvalds return len; 45601da177e4SLinus Torvalds } 45611da177e4SLinus Torvalds 4562d60874cdSMiklos Szeredi /** 4563fd4a0edfSMiklos Szeredi * vfs_readlink - copy symlink body into userspace buffer 4564fd4a0edfSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4565fd4a0edfSMiklos Szeredi * @buffer: user memory pointer 4566fd4a0edfSMiklos Szeredi * @buflen: size of buffer 4567fd4a0edfSMiklos Szeredi * 4568fd4a0edfSMiklos Szeredi * Does not touch atime. That's up to the caller if necessary 4569fd4a0edfSMiklos Szeredi * 4570fd4a0edfSMiklos Szeredi * Does not call security hook. 4571fd4a0edfSMiklos Szeredi */ 4572fd4a0edfSMiklos Szeredi int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4573fd4a0edfSMiklos Szeredi { 4574fd4a0edfSMiklos Szeredi struct inode *inode = d_inode(dentry); 4575f2df5da6SAl Viro DEFINE_DELAYED_CALL(done); 4576f2df5da6SAl Viro const char *link; 4577f2df5da6SAl Viro int res; 4578fd4a0edfSMiklos Szeredi 457976fca90eSMiklos Szeredi if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { 458076fca90eSMiklos Szeredi if (unlikely(inode->i_op->readlink)) 458176fca90eSMiklos Szeredi return inode->i_op->readlink(dentry, buffer, buflen); 458276fca90eSMiklos Szeredi 458376fca90eSMiklos Szeredi if (!d_is_symlink(dentry)) 4584fd4a0edfSMiklos Szeredi return -EINVAL; 4585fd4a0edfSMiklos Szeredi 458676fca90eSMiklos Szeredi spin_lock(&inode->i_lock); 458776fca90eSMiklos Szeredi inode->i_opflags |= IOP_DEFAULT_READLINK; 458876fca90eSMiklos Szeredi spin_unlock(&inode->i_lock); 458976fca90eSMiklos Szeredi } 459076fca90eSMiklos Szeredi 45914c4f7c19SEric Biggers link = READ_ONCE(inode->i_link); 4592f2df5da6SAl Viro if (!link) { 4593f2df5da6SAl Viro link = inode->i_op->get_link(dentry, inode, &done); 4594f2df5da6SAl Viro if (IS_ERR(link)) 4595f2df5da6SAl Viro return PTR_ERR(link); 4596f2df5da6SAl Viro } 4597f2df5da6SAl Viro res = readlink_copy(buffer, buflen, link); 4598f2df5da6SAl Viro do_delayed_call(&done); 4599f2df5da6SAl Viro return res; 4600fd4a0edfSMiklos Szeredi } 4601fd4a0edfSMiklos Szeredi EXPORT_SYMBOL(vfs_readlink); 46021da177e4SLinus Torvalds 4603d60874cdSMiklos Szeredi /** 4604d60874cdSMiklos Szeredi * vfs_get_link - get symlink body 4605d60874cdSMiklos Szeredi * @dentry: dentry on which to get symbolic link 4606d60874cdSMiklos Szeredi * @done: caller needs to free returned data with this 4607d60874cdSMiklos Szeredi * 4608d60874cdSMiklos Szeredi * Calls security hook and i_op->get_link() on the supplied inode. 4609d60874cdSMiklos Szeredi * 4610d60874cdSMiklos Szeredi * It does not touch atime. That's up to the caller if necessary. 4611d60874cdSMiklos Szeredi * 4612d60874cdSMiklos Szeredi * Does not work on "special" symlinks like /proc/$$/fd/N 4613d60874cdSMiklos Szeredi */ 4614d60874cdSMiklos Szeredi const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) 4615d60874cdSMiklos Szeredi { 4616d60874cdSMiklos Szeredi const char *res = ERR_PTR(-EINVAL); 4617d60874cdSMiklos Szeredi struct inode *inode = d_inode(dentry); 4618d60874cdSMiklos Szeredi 4619d60874cdSMiklos Szeredi if (d_is_symlink(dentry)) { 4620d60874cdSMiklos Szeredi res = ERR_PTR(security_inode_readlink(dentry)); 4621d60874cdSMiklos Szeredi if (!res) 4622d60874cdSMiklos Szeredi res = inode->i_op->get_link(dentry, inode, done); 4623d60874cdSMiklos Szeredi } 4624d60874cdSMiklos Szeredi return res; 4625d60874cdSMiklos Szeredi } 4626d60874cdSMiklos Szeredi EXPORT_SYMBOL(vfs_get_link); 4627d60874cdSMiklos Szeredi 46281da177e4SLinus Torvalds /* get the link contents into pagecache */ 46296b255391SAl Viro const char *page_get_link(struct dentry *dentry, struct inode *inode, 4630fceef393SAl Viro struct delayed_call *callback) 46311da177e4SLinus Torvalds { 4632ebd09abbSDuane Griffin char *kaddr; 46331da177e4SLinus Torvalds struct page *page; 46346b255391SAl Viro struct address_space *mapping = inode->i_mapping; 46356b255391SAl Viro 4636d3883d4fSAl Viro if (!dentry) { 4637d3883d4fSAl Viro page = find_get_page(mapping, 0); 4638d3883d4fSAl Viro if (!page) 46396b255391SAl Viro return ERR_PTR(-ECHILD); 4640d3883d4fSAl Viro if (!PageUptodate(page)) { 4641d3883d4fSAl Viro put_page(page); 4642d3883d4fSAl Viro return ERR_PTR(-ECHILD); 4643d3883d4fSAl Viro } 4644d3883d4fSAl Viro } else { 4645090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 46461da177e4SLinus Torvalds if (IS_ERR(page)) 46476fe6900eSNick Piggin return (char*)page; 4648d3883d4fSAl Viro } 4649fceef393SAl Viro set_delayed_call(callback, page_put_link, page); 465021fc61c7SAl Viro BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); 465121fc61c7SAl Viro kaddr = page_address(page); 46526b255391SAl Viro nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); 4653ebd09abbSDuane Griffin return kaddr; 46541da177e4SLinus Torvalds } 46551da177e4SLinus Torvalds 46566b255391SAl Viro EXPORT_SYMBOL(page_get_link); 46571da177e4SLinus Torvalds 4658fceef393SAl Viro void page_put_link(void *arg) 46591da177e4SLinus Torvalds { 4660fceef393SAl Viro put_page(arg); 46611da177e4SLinus Torvalds } 46624d359507SAl Viro EXPORT_SYMBOL(page_put_link); 46631da177e4SLinus Torvalds 4664aa80deabSAl Viro int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 4665aa80deabSAl Viro { 4666fceef393SAl Viro DEFINE_DELAYED_CALL(done); 46676b255391SAl Viro int res = readlink_copy(buffer, buflen, 46686b255391SAl Viro page_get_link(dentry, d_inode(dentry), 4669fceef393SAl Viro &done)); 4670fceef393SAl Viro do_delayed_call(&done); 4671aa80deabSAl Viro return res; 4672aa80deabSAl Viro } 4673aa80deabSAl Viro EXPORT_SYMBOL(page_readlink); 4674aa80deabSAl Viro 467554566b2cSNick Piggin /* 467654566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 467754566b2cSNick Piggin */ 467854566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 46791da177e4SLinus Torvalds { 46801da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 46810adb25d2SKirill Korotaev struct page *page; 4682afddba49SNick Piggin void *fsdata; 4683beb497abSDmitriy Monakhov int err; 4684c718a975STetsuo Handa unsigned int flags = 0; 468554566b2cSNick Piggin if (nofs) 468654566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 46871da177e4SLinus Torvalds 46887e53cac4SNeilBrown retry: 4689afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 469054566b2cSNick Piggin flags, &page, &fsdata); 46911da177e4SLinus Torvalds if (err) 4692afddba49SNick Piggin goto fail; 4693afddba49SNick Piggin 469421fc61c7SAl Viro memcpy(page_address(page), symname, len-1); 4695afddba49SNick Piggin 4696afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4697afddba49SNick Piggin page, fsdata); 46981da177e4SLinus Torvalds if (err < 0) 46991da177e4SLinus Torvalds goto fail; 4700afddba49SNick Piggin if (err < len-1) 4701afddba49SNick Piggin goto retry; 4702afddba49SNick Piggin 47031da177e4SLinus Torvalds mark_inode_dirty(inode); 47041da177e4SLinus Torvalds return 0; 47051da177e4SLinus Torvalds fail: 47061da177e4SLinus Torvalds return err; 47071da177e4SLinus Torvalds } 47084d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 47091da177e4SLinus Torvalds 47100adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 47110adb25d2SKirill Korotaev { 47120adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 4713c62d2555SMichal Hocko !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); 47140adb25d2SKirill Korotaev } 47154d359507SAl Viro EXPORT_SYMBOL(page_symlink); 47160adb25d2SKirill Korotaev 471792e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 47186b255391SAl Viro .get_link = page_get_link, 47191da177e4SLinus Torvalds }; 47201da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4721